JP2005231233A - Image receiving sheet and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image receiving sheet and an image forming method which enable attainment of high sensitivity, while reducing the stain of an image and the deterioration of color reproducibility due to ablation of a photothermal conversion layer of an ink sheet, in a thermal transfer image recording system using the thermal transfer ink sheet and the image receiving sheet. <P>SOLUTION: In the image receiving sheet having a cushion layer and an image receiving layer on a support, a support-side adjacent layer to the image receiving layer contains a substance producing gas by laser exposure. Preferably, the support-side adjacent layer to the image receiving layer containing the substance producing the gas by the laser exposure or a support-side adjacent layer to that layer contains a photothermal conversion substance, the gas produced by the laser exposure is nitrogen, and the support-side adjacent layer to the image receiving layer contains a mat material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image receiving sheet and an image forming method, and more specifically, a thermal transfer image forming method using a thermal transfer ink sheet (hereinafter abbreviated as ink sheet) and an image receiving sheet, and forming a high-resolution image using laser light, and the method used The present invention relates to an image receiving sheet. In particular, the present invention relates to an image receiving sheet and an image forming method useful for producing a color proof or mask image in the printing field by laser recording from a digital image signal.

  In recent years, with the spread of image forming technology from digital data, the need for digital color proof (direct digital color proof: DDCP) is increasing, particularly in the printing field.

  In such DDCP, color reproduction and stability reproduction of printed matter are required, and laser thermal transfer technology is employed. Specifically, a thermal transfer ink sheet having a photothermal conversion layer and an ink layer, and an image receiving sheet having an image receiving layer for receiving the ink layer of the ink sheet, the ink layer surface of the ink sheet and the image receiving layer surface of the image receiving sheet are provided. There is a disclosure such as a technique of performing imagewise laser exposure from the ink sheet side, photothermal conversion, thermal transfer of the ink layer to the image receiving layer side, and thermal transfer from the image receiving sheet carrying the image to the final recording medium. (For example, refer to Patent Document 1).

  However, for this method, it is desired to shorten the image output time, that is, to increase the sensitivity. To achieve this, the following approach can be considered. One is improvement of the laser light source, and the other is improvement of the ink sheet and / or the image receiving sheet.

  As a method for improving the laser light source, there are a method of increasing the laser power and an increase of the laser spot area for image recording. However, when the laser power is increased, the thermal energy received by the photothermal conversion layer of the ink sheet becomes excessive, and the layer Destruction occurs and a phenomenon (ablation) of transferring and transferring to the ink layer occurs. If ablation occurs, the color reproducibility of the image decreases. In order to increase the laser spot area, the number of LDs (laser diodes) of the light source must be increased. However, since the LD is expensive, the cost of the image recording apparatus is increased.

  On the other hand, as an improvement method of the ink sheet, an infrared absorbing cyanine colorant or a near infrared absorbing substance is added to the ink layer as a photothermal conversion substance (see, for example, Patent Document 2 and Patent Document 3), or in the photothermal conversion layer. A method of containing a gas generating polymer (see, for example, Patent Document 4) is disclosed.

  However, these methods all improve the transferability of the ink layer, but the color reproducibility is lowered due to the colorability of the photothermal conversion material and the occurrence of ablation of the photothermal conversion layer. In contrast, a method of providing a gas generating layer between the photothermal conversion layer and the ink layer is disclosed (for example, see Patent Document Information 5), but the cost increases as the number of layers increases.

In the above-described image forming method by laser exposure, laser is irradiated from the surface opposite to the ink layer surface of the ink sheet, but a part of the laser light reaching the photothermal conversion layer passes through the ink layer and reaches the image receiving sheet. In the present invention, this light is utilized to increase the sensitivity by increasing the adhesion between the image receiving layer and the ink layer with the pressure of the generated gas.
JP 2000-37956 A JP 2000-25350 A JP 2000-141891 A JP 2001-138649 A Japanese Patent Laid-Open No. 7-1995834

  An object of the present invention is an image receiving sheet capable of achieving high sensitivity while suppressing image contamination and color reproducibility deterioration due to ablation of the photothermal conversion layer of the ink sheet in a thermal transfer image recording system using a thermal transfer ink sheet and an image receiving sheet. An object is to provide an image forming method.

  The object of the present invention can be achieved by the following constitution.

(Claim 1)
An image receiving sheet having at least a cushion layer and an image receiving layer on a support, wherein the adjacent layer on the support side of the image receiving layer contains a substance that generates a gas by laser exposure.

(Claim 2)
The image-receiving sheet according to claim 1, wherein the support-side adjacent layer of the image-receiving layer containing a substance that generates gas by laser exposure or the support-side adjacent layer of the adjacent layer contains a photothermal conversion substance.

(Claim 3)
3. The image receiving sheet according to claim 1, wherein the gas generated by the laser exposure is nitrogen.

(Claim 4)
The image receiving sheet according to any one of claims 1 to 3, wherein the support layer side adjacent layer of the image receiving layer contains a mat material.

(Claim 5)
A thermal transfer ink sheet having at least a photothermal conversion layer and an ink layer on a support and the image receiving sheet according to any one of claims 1 to 4, and irradiating a laser beam to the ink layer of the thermal transfer ink sheet. An image forming method comprising recording an image by transferring a laser beam irradiation region onto an image receiving layer of the image receiving sheet.

  By using the image receiving sheet of the present invention, high-sensitivity thermal transfer recording can be performed without causing image contamination or color reproducibility deterioration.

  Hereinafter, the image receiving sheet of the present invention, the thermal transfer ink sheet used in combination with the image receiving sheet, and the image forming method will be sequentially described.

<Image-receiving sheet>
In the image-receiving sheet of the present invention, at least a cushion layer, an image-receiving layer, and a layer containing a gas generating substance (by laser exposure) are provided on a support, but a release layer and an intermediate layer are provided as necessary. Can do. Among these layers excluding the image receiving layer, a gas generating substance is contained in the layer adjacent to the support side of the image receiving layer. Further, a back coat layer may be provided on the surface of the support opposite to the image receiving layer.

(Support)
The support used for the ink sheet described later can be similarly used. Further, the support may have minute voids. Such a support is made by mixing a melt obtained by mixing a thermoplastic resin and an inorganic pigment or a filler made of a polymer incompatible with the thermoplastic resin into a single layer or multilayer film by a melt extruder. Further, it can be produced by stretching in 1 to 2 axes. In this case, the porosity is determined by the selection of resin and filler, mixing ratio, stretching conditions, and the like.

  As the thermoplastic resin, a polyolefin resin such as polypropylene and a polyethylene terephthalate resin are preferable because they have good crystallinity and stretchability and can easily form voids. It is preferable to use the polyolefin resin or polyethylene terephthalate resin as a main component and to use a small amount of other thermoplastic resin in combination with it as appropriate. As the inorganic pigment used as the filler, those having an average particle diameter of 1 to 20 μm are preferable, and calcium carbonate, clay, diatomaceous earth, titanium oxide, aluminum hydroxide, silica and the like can be used. In addition, as the incompatible resin used as the filler, when polypropylene is used as the thermoplastic resin, it is preferable to combine polyethylene terephthalate as the filler. Details of the support having fine voids are described in JP-A-2001-105752. The content of the filler such as an inorganic pigment in the support is generally about 2 to 30% by volume.

  The thickness of the support is preferably thicker than that of the ink sheet from the viewpoint of ease of superposition, generally about 25 to 200 μm, more preferably 50 to 150 μm.

(Image receiving layer)
An image receiving layer is provided on the surface of the image receiving sheet in order to hold the thermally transferred ink layer. The image receiving layer is formed mainly of an organic polymer binder. The binder is preferably a thermoplastic resin, and a polymer used for an ink layer of an ink sheet to be described later or various kinds thereof listed as the composition can be appropriately selected and used.

  The binder of the image receiving layer is preferably a polymer having a glass transition temperature (Tg) lower than 90 ° C. in order to obtain an appropriate adhesive force with the ink layer, but in order to prevent blocking, the Tg is 30 ° C. or higher. It is preferable that Moreover, the thing whose softening point by TMA measurement is 40 degreeC or more is preferable, More preferably, it is 40-80 degreeC. In addition, it is preferable to use a polymer that is the same as or similar to the binder polymer of the ink layer from the viewpoint of improving the adhesion with the ink layer during laser recording and improving the sensitivity and image strength.

Specific examples include adhesives such as polyvinyl acetate emulsion adhesive, chloroprene adhesive, epoxy resin adhesive, natural rubber, chloroprene rubber, butyl rubber, polyacrylate ester, nitrile rubber, polysulfide , Adhesive materials such as silicon rubber and petroleum resin, recycled rubber, SBR, polybutadiene, polyisoprene, polyvinyl ether, ionomer resin, SIS, SEBS, acrylic resin, ethylene copolymer, ethylene-vinyl chloride copolymer, ethylene -Acrylic acid copolymer, ethylene-vinyl acetate resin (EVA), vinyl chloride graft EVA resin, EVA graft vinyl chloride resin, urethane resin, polyester resin, polyolefin resin, various modified olefins, polyvinyl butyral, ethylene-vinyl acetate copolymer Coalescence Ethylene copolymers such as ethylene-acrylic acid copolymers, vinyl chloride copolymers such as polyvinyl chloride and vinyl chloride-vinyl acetate copolymers, polyvinylidene chloride, vinylidene chloride copolymers, polystyrene, styrene-acrylic acid Examples thereof include styrene copolymers such as copolymers, styrene-maleic acid ester copolymers, and polyvinyl acetate. In addition, a fluorine-containing resin, a fluorine-containing polysiloxane, a compound formed from a silicate oligomer, a compound formed from a SiO ₂ sol and a reactive organic silicon compound, or the like is used. Specific examples include JP-A-7-126552, JP-A-7-188582, JP-A-8-48935, JP-A-8-100136, JP-A-9-220169, JP-A-9-272169, JP-A-2001-91705, and the like. It is the compound described. Two or more of these binders can be mixed and used.

  The elongation percentage of the binder suitably used in the image receiving layer is preferably from 1 to 1000%, more preferably from 10 to 800%. If the elongation is less than 1%, pinhole-like missing may occur at the time of transfer to the final recording medium. On the other hand, if it exceeds 1000%, the peeling force increases, which is not preferable for peeling in a large size.

  In the image receiving layer, known additives such as surfactants, antioxidants, UV absorbers, preservatives, antistatic agents and the like can be used as necessary.

The film thickness of the image-receiving layer in the present invention is preferably ^{0.2~10g / m 2, 0.5~5g / m} 2 is more preferable. The average roughness Ra of the image-receiving layer surface is preferably 0.05 to 0.4 μm, and the Ra value is measured based on JIS B0601 using a surface roughness measuring machine (Surfcom: manufactured by Tokyo Seiki Co., Ltd.). Can do.

In addition, it is preferable that the charged potential of the image receiving layer is -100 to 100V after 1 second of grounding after the image receiving sheet is charged according to US federal government test standard 4046. It is preferable that the surface resistivity of the image receiving layer is not more than ⁹ Omega 10 at 23 ℃ · 55% RH (relative humidity). The coefficient of static friction on the surface of the image receiving layer is preferably 0.2 or less.

(Gas generating material)
The present invention is characterized in that a layer containing a substance that generates gas by laser exposure (gas generating substance) is provided as an adjacent layer on the support side of the image receiving layer. The adjacent layer may be any layer such as a cushion layer and an intermediate layer, which will be described later, but a layer that can be homogeneously mixed with the components constituting these layers is appropriately selected and used.

  The gas generating polymer may be any polymer that liberates gas when rapidly heated, for example, when its structure is irradiated with an infrared laser, but the main generated gas is preferably nitrogen gas in consideration of environmental suitability.

A polymer that liberates nitrogen gas by heating generally has a thermally decomposable functional group. The polymer may itself be gas-releasing and may include dispersions or adducts of materials that can decompose upon irradiation to generate gas, such as diazonium salts and polymers. Specific examples of suitable thermally decomposable functional groups include azide, alkylazo, diazo, diazonium, diazirino, nitro, difluoroamino, CF (NO ₂ ) ₂ , cyano, nitrato, triazole and the like. Thermally decomposable groups either by pre-polymerization or by modification of existing polymers, for example by diazotization of aromatic rings using sodium nitrate or the like, or diazo transfer to amines or β-diketones using tosyl azide in the presence of triethylamine. May be introduced into the gas generating polymer.

Preferred gas generating polymers in the present invention have the structure of the following formula:
General formula (I) [X- (R) _n- ] _m -L
In the formula, X represents a hydroxyl group, an azido group, a mercapto group or an amino group (including monoalkyl and monoaryl-substituted amino groups), and R represents a divalent monomer group containing an N ₃ group, such as —CH ₂ CH (CH _{2 N 3) O -, -} CH 2 C (CH 3) (CH 2 N 3) CH 2 O -, - CH (CH 2 N 3) CH 2 O -, - CH 2 C (CH 2 N 3) 2 _{CH 2 O -, - CH (} CH 2 N 3) CH (CH 2 N 3) O- and _{-CH 2 CH (N 3) CH} 2 O- and the like of cyclic ethers such as -CH ₂ CH (CH ₂ N _{3 ) S -, - CH 2 C} (CH 2 N 3) 2 CH 2 S -, - CH (CH 2 N 3) CH (CH 2 N 3) S- , and _{-CH 2 CH (N 3) CH} 2 S- cyclic sulfide etc., for example, _{-CH 2 CH (CH 2 N 3} ) NR 1 -, - CH (CH 2 N 3) CH 2 NR 1 -, - CH 2 C (CH 2 _{3) 2 CH 2 NR 1 -} , - CH (CH 2 N 3) CH (CH 2 N 3) NR 1 - and _{-CH 2 CH (N 3) CH} 2 NR 1 - cyclic amine such as (R ₁ is an alkyl Group, an aryl group, an aralkyl group, an alkaryl group or the like, and L represents a 1 to 4 valent alkyl group residue. m represents an integer of 1 to 4, and n represents an integer of 1 or more, preferably 5 or more, more preferably 10 or more.

  Examples of the monovalent alkyl group include methyl and ethyl, and examples of the polyvalent alkyl group include ethylene, methylene, propylene, 1,2,3-propanetriyl, 2,2-dimethylene-1,3-propanedil and the like. Of these, 1,2,3-propanetriyl is preferable.

  The gas generating polymer can be synthesized by known methods, for example, the methods disclosed in US Pat. Nos. 3,645,917 and 4,879,419.

  The coating strength can also be improved by using one or more crosslinking agents in combination with the gas generating polymer of general formula (I). A suitable crosslinking agent is selected according to the side chain group of the gas generating polymer. For example, if a hydroxyl group is present in the gas generating polymer, polyol crosslinking agents (isocyanates) can be used. Further, when a side group capable of radical polymerization, for example, acryloyl group is bonded to the polymer skeleton, a radical initiator may be used as a crosslinking agent.

  Preferably, a polyol crosslinker is used in combination with a gas generating polymer having multiple hydroxyl end groups. Preferred crosslinking agents in this case include, but are not limited to, polyisocyanates such as hexamethylene diisocyanate, diphenylmethane diisocyanate, bis (4-isocyanatocyclohexyl) methane, and 2,4-tolylene diisocyanate.

  In addition, as the gas generating polymer, polyoxetanes represented by the following general formula (II) are preferably used.

Formula (II) —CH ₂ —C (R ₁₁ R ₁₂ ) —CH ₂ —O—
In the formula, R ₁₁ and R ₁₂ are each independently a thermally decomposable nitrogen-containing group such as an azide group, a nitro group, a nitrato group, a triazole group and the like. An example of a suitable azide group is —CH ₂ N ₃ . The preferred polyoxetane is poly [bis (azidomethyl) oxetane].

  The gas generating polymer represented by the general formula (II) can be synthesized by a known procedure as disclosed in, for example, US Pat. No. 3,694,383.

  Another preferred gas generating polymer is an energetic copolymer. An active copolymer can be defined as a polymer containing a functional group that decomposes exothermically to generate gas, shock wave, pressure, and the like when heated on a time scale of milliseconds to nanoseconds above a certain critical temperature. Preferably, the active copolymer has repeat units derived from different monomers, one or both of which have side chain active nitrogen-containing groups such as azido groups, nitro groups, nitrato groups or nitramino groups. Preferably, the monomer preferably has a cyclic ether structure, specifically a cyclic oxide having 3 to 6 cyclic atoms. The active monomer is preferably an azide, nitro, triazole or nitrato derivative of oxirane, oxetane or tetrahydrofuran. Examples of such active copolymers include poly [bis (azidomethyl) oxetane] (BANO), glycidyl azide polymers (GAP), polyvinyl nitrate (PVN), nitrocellulose and polycarbonates. The copolymerization of the monomers is preferably performed by cationic polymerization. The aforementioned active copolymers and methods for their synthesis are disclosed in US Pat. No. 4,483,978.

  The active copolymers may be materials containing active additives, gas forming additives or catalysts for their thermal or photochemical decomposition. The decomposition temperature is lowered and can be used as either a plasticizer or a decomposition initiator (kicker). Examples of such additives (non-inclusive) are the active molecules RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine), TNT (trinitrotoluene) and PETN (pentaerythritol tetranitrate). ) A gas forming additive is a molecule that decomposes thermally to produce a large amount of gaseous product. Specifically, diazonium salts (such as diazonium 4-methoxybenzenetetrafluoroborate), azides (such as 4-azidobenzoic acid), and “blowing agents” (2,2′-azobis-2-methyl) -Butyronitrile, p-toluenesulfonyl hydrazide, etc.).

  Acids, bases and organometallic species such as ferric acetylacetonate may be added as catalysts for lowering the decomposition temperature of the active polymer or additive.

  In order to increase the image forming speed of the thermal transfer material used in the present invention, one or more azide decomposition accelerators may be added to the gas generating polymer layer or a layer adjacent thereto. Accelerators useful for azide decomposition include known materials such as alkyl azide compounds, metal complexes, ferrous acetylacetonate, stannous chloride, magnesium chloride, ferric chloride, zinc bromide and benzoic acid. Examples include acids, acetic acid, proton acids such as p-toluenesulfonic acid, radical initiators such as benzoyl peroxide and t-butylperbenzoic acid, and phosphines such as triphenylphosphine.

The gas generating polymer substance can be added to the adjacent layer on the support side of the image receiving layer in the range of 0.3 to 2.0 g / m ² , preferably 0.5 to 1.5 g / m ² .

(Photothermal conversion agent)
In this invention, a photothermal conversion agent can be contained with the said gas generating substance. Gas generation can be promoted by containing a photothermal conversion agent.

  As the photothermal conversion agent, the same ones described in the section of the photothermal conversion layer used in the ink sheet described later can be used, among which cyanine, polymethine, azurenium, squalium, thiopyrylium, Organic compounds such as naphthoquinone and anthraquinone dyes, phthalocyanine, azo and thioamide organometallic complexes are preferred. Specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-280750, JP-A-1-293342, JP-A-2-2074, JP-A-3-26593, 3-30991, 3-3-3891, 3-36093, 3-36094, 3-36095, 3-42281, 3-97589, 3-103476, etc. Compounds. Of these, those having low colorability are preferred.

(Cushion layer)
In the image receiving sheet of the present invention, a cushion layer is provided between the support and the image receiving layer. By providing a cushion layer, even if foreign matter is mixed between the ink sheet and the image receiving sheet, the gap between the image receiving layer and the image forming layer is reduced due to the deformation action of the cushion layer, resulting in image defect sizes such as white spots. Has the effect of reducing the size. In addition, there is an effect of increasing secondary transferability by heating lamination to various final image recording media. For this reason, the cushion layer requires high fluidity under heating or pressure. In order to satisfy such characteristics, the cushion layer is a layer having cushioning properties or elasticity (hereinafter also referred to as cushioning properties), and can be sufficiently softened and deformed by heating, or has a low elastic modulus. A material or a material having rubber elasticity is used. In the present invention, the elastic modulus and the penetration can be used as a guide indicating cushioning properties. For example, a layer having an elastic modulus at 25 ° C. of about 9.8 × 10 ^{6 to} 24.5 × 10 ⁷ Pa, or a penetration defined by JIS K 2530-1976 is more preferably 15 to 500 (g). Has been confirmed that a layer of about 30 to 300 (g) exhibits suitable cushioning properties for the formation of color proof images in the printing field, but the required level depends on the intended use of the image. Therefore, it can be selected as appropriate.

  The material used for the cushion layer is preferably a material that exhibits elasticity without fluidity at room temperature, and exhibits remarkable fluidity in a high temperature region exceeding the softening temperature. The cushion layer preferably has a TMA softening point of 40 ° C or higher, more preferably 40 to 80 ° C. The TMA softening point is measured by TMA (Thermal Mechanical Analysis). That is, the temperature of the measurement object is increased while applying a constant load at a constant temperature increase rate, and the phase of the measurement object is observed. 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 using an apparatus such as Thermoflex (manufactured by Rigaku Corporation). For example, when Thermoflex is used, the measurement temperature range is 25 to 200 ° C., and the heating rate is 5 ° C./min, the temperature starts to change when a 10 g load is applied to a 1 mmφ quartz glass pin (needle). TMA softening point.

  The preferred properties of the cushion layer are not necessarily specified only by the type of the material, but preferred properties of the material itself include polyolefin resins, ethylene-vinyl acetate copolymers, ethylene-ethyl acrylate copolymers, polybutadiene resins. , Styrene-butadiene copolymer (SBR), styrene-ethylene-butylene-styrene copolymer (SEBS), acrylonitrile-butadiene copolymer (NBR), polyisoprene resin (IR), styrene-isoprene copolymer (SIS) ), Acrylate copolymer, polyester resin, polyurethane resin, acrylic resin, butyl rubber, polynorbornene and the like. Among these, those having a relatively low molecular weight easily satisfy the requirements of the present invention, but are not necessarily limited in relation to the material.

  The cushion layer can be provided by applying a solution in which the above-described material is dissolved in an organic solvent, but can also be formed by application in the form of an aqueous dispersion such as latex or emulsion. In addition, a water-soluble resin can also be used. These resins can be used alone or in combination as required.

  Moreover, even if it is a raw material other than the above, a preferable characteristic can be provided to the cushion layer by adding various additives. Examples of such additives include low melting point substances such as wax, plasticizers, thermal solvents, and tackifiers. Specific examples of waxes include plant waxes such as carnauba wax, wood wax, aucuric wax, and espal wax; animal waxes such as beeswax, insect wax, shellac wax, and whale wax; paraffin wax, microcrystal wax, and polyethylene wax And petroleum waxes such as ester wax and acid wax; and waxes such as mineral wax such as montan wax, ozokerite and ceresin. Besides these waxes, palmitic acid, stearic acid, margaric acid Higher fatty acids such as behenic acid; higher alcohols such as palmityl alcohol, stearyl alcohol, behenyl alcohol, marganyl alcohol, myricyl alcohol, eicosanol; higher fatty acids such as cetyl palmitate, myricyl palmitate, cetyl stearate, myricyl stearate S Le; acetamide, amides propionic acid, palmitic acid amide, stearic acid amides such as amide wax; and stearylamine, behenylamine, higher amines such as palmityl amine. Among these, those having a solid at room temperature are preferred, those having a melting point of 40 to 130 ° C. are particularly preferred, and those having a melting point of 70 to 110 ° C. are more preferred.

  Specific examples of the plasticizer, thermal solvent, and tackifier include phthalic acid ester, adipic acid ester, glycol ester, fatty acid ester, phosphoric acid ester, and chlorinated paraffin. In addition, various additives described in, for example, “Practical Handbook for Additives for Plastics and Rubber”, Chemical Industry Co., Ltd. (published in 1970) can be added.

  The additive amount and the like of these additives may be selected in an amount necessary for expressing preferable physical properties in combination with the base cushion layer material, and is not particularly limited. It is preferably at most 5 mass%.

  As a method of forming the cushion layer, there is a method in which the above-mentioned material dissolved in a solvent or dispersed in a latex is applied by a blade coater, roll coater, bar coater, curtain coater, gravure coater, etc., extrusion lamination by hot melt Laws can also be applied. It is also possible to use a void-structure resin layer obtained by foaming a cushioning or thermoplastic resin as a special cushion layer.

  The film thickness of the cushion layer is preferably 5 μm or more, more preferably 10 μm or more. If the thickness of the cushion layer is less than 5 μm, image loss may occur during retransfer to the final recording medium.

(Middle layer)
In the image-receiving sheet of the present invention, an intermediate layer having a thickness of about 0.1 to 2 μm can be provided in order to improve the peelability when the image-receiving layer is secondarily transferred to the final recording medium. If the layer thickness is too large, the performance of the cushion layer becomes difficult to appear, and therefore it is necessary to adjust depending on the type of the intermediate layer. The binder resin constituting the intermediate layer needs to have a tensile strength of 1 to 1000 MPa, more preferably 2 to 500 MPa. If the tensile strength is lower than 1 MPa, it cannot follow the softening of the cushion layer and is difficult to use in production. On the other hand, when the pressure is higher than 1000 MPa, transfer to the final recording medium is largely unfavorable. The elongation percentage of the resin is preferably 0.1 to 100%, and if it is less than 0.1%, it cannot follow the softening of the cushion layer, and if it is more than 100%, the peeling force when transferred to paper with large unevenness is large. It is not preferable. However, preferable resin properties are finally properties as an intermediate layer, and may be realized by mixing with various additives. Specific examples include polyolefin, polyester, polyvinyl acetal, polyvinyl formal, polyparabanic acid, polymethyl methacrylate, polycarbonate, ethyl cellulose, nitrocellulose, methyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, polyvinyl alcohol, polyvinyl chloride, silicone resin, urethane. Thermosetting resins having a Tg of 65 ° C. or higher such as resins, fluorine-based resins, styrenes such as polystyrene and acrylonitrile styrene, and those obtained by crosslinking these resins, polyamides, polyimides, polyetherimides, polysulfones, polyethersulfones, and aramids; A cured product of these resins may be mentioned. As the curing agent, general curing agents such as isocyanate and melamine can be used.

  Further, as a material that gives the effect of extremely low adhesion to the image receiving layer during cooling, a heat-meltable compound such as waxes or a binder, or a thermoplastic resin may be contained. Examples of the hot-melt compound include substances described in JP-A-63-193886. In particular, microcrystalline wax, paraffin wax, carnauba wax and the like are preferably used. As the thermoplastic resin, an ethylene copolymer such as an ethylene-vinyl acetate resin, a cellulose resin, or the like is preferably used. Furthermore, higher fatty acids, higher alcohols, higher fatty acid esters, amides, higher amines and the like can be added as necessary as additives.

  Another structure of the intermediate layer is a layer having releasability due to cohesive failure by melting or softening when heated. Such an intermediate layer preferably contains a supercooling substance. Examples of the supercooled substance include poly-ε-caprolactone, polyoxyethylene, benzotriazole, tribenzylamine, and vanillin.

  In addition, a matting agent can be added for the purpose of adjusting the gloss of the image formed on the final recording medium. When a matting agent is added to the intermediate layer, the amount of matting agent added to the image receiving layer may be a minimum amount that can ensure adhesion with the ink layer. Organic or inorganic fine particles can be used as the matting agent. Examples of the organic matting agent include polymethyl methacrylate (PMMA), polystyrene, polyethylene, polypropylene, fine particles of other radical polymerization polymers, fine particles of condensation polymers such as polyester and polycarbonate, fine particles of fluorine resin, silicone resin, and the like. . In order to increase the strength and solvent resistance of the particles, crosslinked organic fine particles are more preferable.

The addition amount of the matting agent cannot be defined unconditionally due to the relationship between the particle size and the weight, but is preferably used in the range of 0.1 to 50% by mass, particularly preferably 0.5 to 40% by mass. It is. Although there is no restriction | limiting in particular in the specific gravity of the particle | grains to be used, Preferably it is 0.1-1.5, More preferably, it is 0.3-1.4, Most preferably, the thing of 0.5-1.3 is good. Amount with the matting agent is preferably 0.3 to 10 / m ^2, more preferably 0.3 to 5 g / m ^2. Is necessary to 0.3μm or more of the particles contained 5 mg / m ² or more, 6~600mg / m ² is more preferable. The dispersion coefficient (σ) of the particle size distribution of the matting agent is preferably 0.5 or less, more preferably 0.3 or less, and particularly preferably 0.15 or less.

  In addition to this, it is preferable to add a release agent, a conductive agent, a surfactant, an antioxidant, a UV absorber, and the like as necessary. Among them, the release agent is important, and the release surface area is increased by adding the matting agent, so that the release force tends to increase, and various conventionally known release agents are added to the intermediate layer so as to obtain an optimum release force. This is a preferred embodiment. The release agent is preferably one having little transferability to the image receiving layer when the image receiving layer is provided. Thereby, the fluctuation | variation of the ink layer transfer property with respect to an image receiving layer can be suppressed.

  The intermediate layer may be provided by solvent coating, but can also be formed by coating in the form of an aqueous dispersion such as latex or emulsion. In addition, a water-soluble resin can also be used. These resins can be used alone or as a mixture as required. As a method for forming the intermediate layer, application by a blade coater, roll coater, bar coater, curtain coater, gravure coater, or the like, extrusion lamination by hot melt, or the like can be applied. Further, there is a method in which the material is dissolved in a solvent or dispersed in a latex form on the temporary base, and the temporary base is peeled off after bonding the material applied by the above method and the cushion layer.

(Back coat layer)
A backcoat layer can be provided on the surface opposite to the surface on which the image receiving layer is provided in order to provide functions such as running stability, heat resistance, and antistatic properties. The back coat layer can be formed by applying a back coat layer coating solution in which a binder resin is dissolved in a solvent or a binder resin and a mat material having a particle size of 2 to 30 μm are dissolved or dispersed in a solvent to the back surface of the support. .

  Binders used in the back coat layer include gelatin, polyvinyl alcohol, 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, polyester resin, Teflon (R) resin, polyvinyl butyral resin, vinyl chloride resin, polyvinyl acetate, polycarbonate, organic boron compounds, aromatic esters, fluorination General-purpose polymers such as polyurethane and polyethersulfone can be used. Crosslinking using a crosslinkable water-soluble binder as the binder of the backcoat layer is effective in preventing the mat material from falling off and improving the scratch resistance of the backcoat. It is also very effective for blocking during storage. For this crosslinking means, any one or combination of heat, actinic light, pressure, etc. can be employed without particular limitation depending on the characteristics of the crosslinking 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 adhesion to the support.

  The back coat layer preferably contains a mat material. The mat material preferably added to the back coat layer is preferably organic or inorganic fine particles. Examples of the organic mat material include fine particles of polymethyl methacrylate, polystyrene, polyethylene, polypropylene, and other radical polymerization polymers, fine particles of condensation polymers such as polyester and polycarbonate, fine particles of fluorine resin, silicone resin, and the like. In order to increase the strength and solvent resistance of the particles, crosslinked organic fine particles are more preferable.

The back coat layer is preferably provided at a weight 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 powdering off of the mat material are likely to occur. In addition, if the coating is applied greatly exceeding 5 g / m ² , the particle size of a suitable mat material becomes very large, resulting in embossing of the ink layer surface by back coating during storage, especially in thermal transfer for transferring a thin ink layer. The recorded image is likely to be missing or uneven.

The mat material preferably has a number average particle size 1 to 20 μm larger than the film thickness of only the binder of the backcoat layer. Among the mat material, 2 [mu] m or more particles having a particle size of 5 mg / m ² or more is required, preferably 6~600mg / m ^2. This in particular improves foreign matter failures. Further, by using a narrow particle size distribution such that a value σ / rn (= coefficient of variation of the 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, 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 variation coefficient is more preferably 0.15 or less.

An antistatic agent is preferably added to the backcoat layer in order to prevent adhesion of foreign matters due to frictional charging with the transport roll during sheet supply. The antistatic agent is appropriately selected from various surfactants and conductive agents so that the surface resistance of the layer is 10 ¹² Ω or less, more preferably 10 ⁹ Ω or less under the conditions of 23 ° C. and 50% RH. Can be used. Specifically, in addition to cationic surfactants, anionic surfactants, nonionic surfactants, polymer antistatic agents, conductive fine particles, “11290 chemical products”, Chemical Industry Daily, 875-876. The compounds described on pages etc. are widely used. As the antistatic agent added to the backcoat layer, among the above-mentioned 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 conductive fine particles, those described in the backcoat layer of the ink sheet described later can be used as they are. In order to impart applicability and releasability, it is also possible to add various activators, silicone oil, mold release agents such as resin, and the like. The backcoat layer is particularly preferably used when the softening point measured by TMA of the cushion layer and the image receiving layer is 70 ° C. or less.

<Ink sheet>
Next, an ink sheet used in combination with the image receiving sheet of the present invention will be described.

  The ink sheet is a sheet having a photothermal conversion function and an ink (coloring material) layer transfer function, and has at least one photothermal conversion layer and an ink layer having a photothermal conversion function on one surface of the support. It is also possible to give the function to the same layer. If necessary, a cushion layer, a release layer and the like can be provided between these layers and the support, and if necessary, a back coat layer can be provided on the opposite surface (back surface) of the support.

(Support)
The support for the ink sheet may be anything as long as it has rigidity, good dimensional stability, excellent smoothness, and can withstand the heat during image formation. Specifically, paper, coated paper, synthetic paper Various papers such as (polypropylene, polystyrene, or composite materials obtained by bonding them to paper), vinyl chloride resin sheet, ABS resin sheet, polyethylene terephthalate (PET) film, polybutylene terephthalate film, polyethylene naphthalate (PEN) ) Film, Polyacrylate film, Polycarbonate (PC) film, Polyetherketone film, Polysulfone film, Polyethersulfone film, Polyetherimide film, Polyimide film, Polyethylene (PE) film, Polypropylene (PP) film, Polystyrene (PS) film, syndiotactic polystyrene (sPS) film, stretched nylon (Ny) film, polyacetate film, polymethyl methacrylate film, etc., or various plastic films or sheets in which two or more layers are laminated, Films or sheets made of metal, films or sheets made of various ceramics, metal plates such as aluminum, stainless steel, chromium, nickel, etc., or thin films of metal laminated or vapor-deposited on resin-coated paper Is mentioned.

The Young's modulus in the longitudinal direction of the support is preferably 19.6 × 10 ^{8 to} 11.8 × 10 ⁹ Pa, and the Young's modulus in the width direction is 24.5 × 10 ^{8 to} 15.7 × 10 ⁹ Pa. preferable. The F-5 value in the longitudinal direction of the support is preferably 4.9 × 10 ^{7 to} 4.9 × 10 ⁸ Pa, and the F-5 value in the width direction of the support is preferably 29.4 × 10 ^{6 to} 29. 4 × 10 ⁷ Pa, and the F-5 value in the longitudinal direction of the support is generally higher than the F-5 value in the width direction of the support, but particularly when the strength in the width direction needs to be increased. That is not the case. Further, the heat shrinkage rate at 100 ° C. for 30 minutes in the longitudinal direction and the width direction of the support is preferably 3% or less, more preferably 1.5% or less, and the heat shrinkage rate at 80 ° C. for 30 minutes is preferably 1% or less, more preferably 0.5% or less. The breaking strength is preferably 4.9 × 10 ^{7 to} 9.8 × 10 ⁸ Pa in both directions, and the elastic modulus is preferably 9.8 × 10 ^{8 to} 19.6 × 10 ⁹ Pa.

  These supports can be subjected to various processes such as dimensional stabilization and antistatic. Examples of the antistatic agent include a cationic surfactant, an anionic surfactant, a nonionic surfactant, a polymer antistatic agent, and conductive fine particles, as well as “11290 Chemical Products”, Chemical Industry Daily, 875- The compounds described on page 876 and the like are widely used. Further, these supports may be subjected to a conventionally known surface modification treatment. Examples of these surface modification treatments include flame emission treatment, sulfuric acid treatment, corona discharge treatment, plasma treatment, glow discharge treatment and the like.

  In addition, an adhesive layer may be provided on the support in order to satisfactorily apply each layer described later on the support. A conventionally well-known thing can be especially used as a contact bonding layer without a restriction | limiting. Examples of the method for providing the adhesive layer include water-based resin coating, solvent-based resin coating, water-based latex coating, and hot melt coating. In general, it is advantageous to provide an adhesive layer at the time of preparing the support from the viewpoints of cost, stability, etc. From this point, for example, acrylic resin, polystyrene resin, polyester resin, urethane resin, polyethylene / vinyl acetate resin A method of applying latex such as is preferable, but not particularly limited thereto. Such base films with an adhesive layer are available from various companies and can be suitably used.

  When an image is formed by irradiating laser light from the ink sheet side, the ink sheet support is preferably transparent. In view of ease of superposition, the thickness of the ink sheet support is preferably thinner than the thickness of the image receiving sheet, generally about 30 to 150 μm, more preferably 50 to 100 μm.

(Photothermal conversion layer)
The photothermal conversion layer is a layer having a photothermal conversion function. If a photothermal conversion material can be added to the ink layer, a photothermal conversion layer is not particularly required, but if the photothermal conversion material is not substantially transparent, the photothermal conversion material is considered separately from the ink layer in consideration of the color reproducibility of the transferred image. It is desirable to provide a conversion layer. The photothermal conversion layer is preferably provided between the support and the ink layer, more preferably between the cushion layer and the ink layer.

  As the binder contained in the photothermal conversion layer, a resin having at least strength capable of forming a layer on a support and having high thermal conductivity is preferable. Furthermore, if the resin has heat resistance and is not decomposed by heat generated from the light-to-heat conversion substance during image recording, the smoothness of the surface of the light-to-heat conversion layer after light irradiation can be maintained even when high-energy light irradiation is performed. Therefore, it is preferable. Specifically, a resin having a thermal decomposition temperature (temperature at which the temperature is reduced by 5% in an air stream at a rate of temperature increase of 10 ° C./min by the TGA method) of 300 ° C. or higher is preferable, and a resin of 400 ° C. or higher is more preferable. .

  Specific examples include polymethyl methacrylate, polycarbonate, polystyrene, ethyl cellulose, nitrocellulose, polyvinyl alcohol, polyvinyl chloride, polyamide, polyimide (preferably described in JP-A-2002-347361), polyetherimide, polysulfone, and polyether. Use general heat-resistant resins such as sulfones and aramids, and polymer compounds composed of polythiophenes, polyanilines, polyacetylenes, polyphenylenes, polyphenylene sulfides, polypyrroles, and derivatives thereof, or mixtures thereof. be able to.

  Moreover, a water-soluble polymer can also be used as a binder of a photothermal conversion layer. A water-soluble polymer is preferable in that it has good releasability from the ink layer, good heat resistance during laser irradiation, and little scattering even when excessively heated. When a water-soluble polymer is used, it is desirable that the photothermal conversion substance is modified to be water-soluble (for example, by introduction of a sulfo group) or dispersed in water.

  Further, by incorporating various release agents into the light-to-heat conversion layer, the peelability between the light-to-heat conversion layer and the ink layer can be increased, and the sensitivity can be improved. Examples of the release agent include silicon release agents (polyoxyalkylene modified silicone oil, alcohol modified silicone oil, etc.), fluorine surfactants (perfluorophosphate ester surfactants, etc.), and other various surfactants. Etc. are effective.

  When using a photothermal conversion substance, although it depends on the light source, a substance that absorbs light and efficiently converts it into heat is good.For example, when using a semiconductor laser as a light source, a substance having an absorption band in the near infrared is preferable. Near-infrared light absorbers include, for example, carbon black, cyanine-based, polymethine-based, azulenium-based, squalium-based, thiopyrylium-based, naphthoquinone-based, anthraquinone-based organic compounds, phthalocyanine-based, azo-based, and thioamide-based organic metals. Complexes and the like are preferably used, and specifically, JP-A-63-139191, JP-A-64-33547, JP-A-1-160683, JP-A-1-280750, JP-A-1-293342, and JP-A-2-2074. 3-26593, 3-30991, 3-34891, 3-36093, 3-36 94 items, the 3-36095 JP, same 3-42281 JP, same 3-97589 Patent, compounds described in the 3-103476 Patent and the like. These can be used alone or in combination of two or more.

  The film thickness of the photothermal conversion layer is preferably from 0.1 to 3 μm, more preferably from 0.2 to 1.0 μm. When carbon black is used as the light-to-heat conversion layer, if the film thickness of the light-to-heat conversion layer exceeds 1 μm, the sensitivity tends to decrease instead of causing the ink layer to be overheated. Since it changes depending on the absorbance of the photothermal conversion layer, it may be selected as appropriate. The content of the photothermal conversion substance in the photothermal conversion layer is usually determined such that the absorbance 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.

  In addition to this, a vapor deposition layer can also be used as the photothermal conversion layer, such as gold, silver, aluminum, chromium, nickel, antimony, tellurium, bismuth, and selenium described in JP-A-52-20842. In addition to the metal black vapor deposition layer, the metal elements of groups 4 to 13, 15 and 16 of the periodic table, and alloys thereof, alloys of these elements with elements of groups 1 to 3, or mixtures thereof Particularly desirable metals include Al, Bi, Sn, In or Zn and alloys thereof, or alloys of these metals with elements of groups 1-3 of the periodic table, or mixtures thereof. Suitable metal oxides or sulfides include Al, Bi, Sn, In, Zn, Ti, Cr, Mo, W, Co, Ir, Ni, Pb, Pt, Cu, Ag, Au, Zr or Te compounds. Or a mixture thereof. Furthermore, the vapor deposition layer of metal phthalocyanines, metal dithiolenes, and anthraquinones is also mentioned. The film thickness of the vapor deposition layer is preferably within 500 mm. The photothermal conversion substance may be the color material itself of the ink layer, and is not limited to the above, and various substances can be used.

The photothermal conversion layer may contain a mat material as necessary. Examples of the mat material contained in the photothermal conversion layer include inorganic fine particles and organic fine particles. Examples of the inorganic fine particles include silica, titanium oxide, aluminum oxide, zinc oxide, magnesium oxide, barium sulfate, magnesium sulfate, aluminum hydroxide, magnesium hydroxide, boron nitride and other metal salts, kaolin, clay, talc, zinc white, Lead white, sieglite, quartz, diatomaceous earth, barlite, bentonite, mica, synthetic mica and the like can be mentioned. Examples of the organic fine particles include resin particles such as fluorine resin particles, guanamine resin particles, acrylic resin particles, styrene-acrylic copolymer resin particles, silicone resin particles, melamine resin particles, and epoxy resin particles. The particle size of the mat material is usually 0.3 to 30 μm, preferably 0.5 to 20 μm, and the addition amount is preferably 0.1 to 100 mg / m ² .

  Examples of the organic solvent for dissolving the binder resin include hexane, cyclohexane, diglyme, xylene, toluene, ethyl acetate, tetrahydrofuran, methyl ethyl ketone, acetone, cyclohexanone, 1,4-dioxane, 1,3-dioxane, dimethyl acetate, N -Methyl-2-pyrrolidone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, γ-butyrolactone, ethanol, methanol, i-propanol, water and the like. The application / drying can be performed using a normal application / drying method.

  If the photothermal conversion layer is inferior in adhesion to the lower layer of the support, it may cause film peeling and color turbidity when peeling the transfer material from the image receiving sheet during light irradiation or after thermal transfer. It is also possible to provide an adhesive layer between the two. As the adhesive layer, it is necessary to select a material so that the adhesive strength between the photothermal conversion layer and the adhesive layer and the support lower layer at the time of ink transfer is larger than the ink peel strength at the time of ink transfer. Generally, conventionally known adhesives such as polyester, urethane, and gelatin can be used. In order to obtain the same effect, a tackifier and an adhesive can be added to the lower layer of the support instead of providing the adhesive layer. When the adhesive layer is poor in heat softening property or thermoplasticity, the effect of heat softening property is reduced. Therefore, the adhesive layer is preferably as thin as possible. The preferred film thickness is 0.5 μm or less, but not limited to this as long as the adhesive layer can fulfill the purpose of the thermal softening layer.

(Ink layer)
The ink layer mainly comprises a colorant and a binder, but may have additives such as a lubricant as necessary. In the laser melting thermal transfer method, the ink layer is a layer that is melted or softened when heated and can be transferred together with the layer, and may not be transferred in a completely molten state.

  Examples of the colorant include inorganic pigments (titanium dioxide, carbon black, graphite, zinc oxide, Prussian blue, cadmium sulfide, iron oxide and lead, zinc, barium and calcium chromates) and organic pigments (azo-based, thioindigo). Pigments, dyes (acidic dyes, direct dyes, disperse dyes, oil-soluble dyes, etc.) such as pigments, anthraquinone, anthanthrone, triphendioxazine pigments, vat dye pigments, phthalocyanine pigments and derivatives thereof, quinacridone pigments, etc. Metal oil-soluble dyes or sublimable dyes). For example, yellow is C.I. I. 21090, C.I. I. 21095, C.I. I. 21100, C.I. I. 21105, C.I. I. 21290, C.I. I. 56298 pigment, magenta is C.I. I. 15850: 1, C.I. I. 15855: 1, C.I. I. 15865: 1, C.I. I. 15865: 2, C.I. I. 15865: 3, C.I. I. 73915, C.I. I. 65300 pigment, cyan is C.I. I. 74160, C.I. I. 69800 pigment, black is C.I. I. 77266 pigment is preferably used. The content of the colorant in the ink layer is not particularly limited as long as it is adjusted so that a desired concentration can be obtained with a desired coating film thickness, but is usually in the range of 5 to 70% by mass of the total solid content of the ink layer. Yes, preferably 10 to 60% by mass.

  Examples of the binder for the ink layer include a hot-melt material and a thermoplastic resin. The hot-melt material is usually a solid or semi-solid material having a melting point measured using Yanagimoto MJP-2 type in the range of 40 to 150 ° C. Specifically, plant waxes such as carnauba wax, wood wax, aucuric wax and espal wax; animal waxes such as beeswax, insect wax, shellac wax and whale wax; paraffin wax, microcrystal wax, polyethylene wax, ester wax, acid Examples thereof include petroleum waxes such as waxes; and waxes such as mineral waxes such as montan wax, ozokerite, and ceresin. Thermoplastic resins include ethylene copolymers, polyamide resins, polyester resins, polyurethane resins, polyolefin resins, styrene resins, styrene-acrylic resins, acrylic resins, vinyl chloride resins, and cellulose resins. Rosin resins, polyvinyl alcohol resins, polyvinyl acetal resins, polyvinyl butyral resins, ionomer resins, petroleum resins, and ink layer binder resins described in JP-A-6-312583. A resin having a TMA softening point of 70 to 150 ° C. is preferably used. In addition to the above thermoplastic resins, elastomers such as natural rubber, styrene butadiene rubber, isoprene rubber, chloroprene rubber, and diene copolymer; rosin derivatives such as ester gum, rosin maleic resin, rosin phenol resin, and hydrogenated rosin And high molecular compounds such as phenol resin, terpene resin, cyclopentadiene resin, and aromatic hydrocarbon resin can also be used.

  By appropriately selecting the heat-melting substance and the thermoplastic substance, it is possible to form an ink layer having a desired heat softening point or a heat-transfer point and having a heat transfer property. In the present invention, an image can be formed by ablation transfer by using a binder having high thermal decomposability. Such binders include polymeric materials that undergo rapid acid-catalyzed partial degradation, preferably at temperatures below 200 ° C. when measured under equilibrium conditions, such as nitrocelluloses, polycarbonates and J.A. M.M. J. et al. Frechet, F.A. Bouchard, J .; M.M. Houlihan, B.H. Kryczke and E.I. Eichler, J. et al. Imaging Science, 30 (2), pages 59-64 (1986), including polymers of the type, and polyurethanes, polyesters, polyorthoesters, and polyacetals, and copolymers thereof. .

  Although it is disclosed in JP-A-62-158092 that a high concentration can be obtained by making the particle diameters of the pigments uniform, various dispersants can be used in order to ensure the dispersibility of the pigment and obtain a good color reproduction. It is effective to use. Examples of other additives include the addition of a plasticizer that increases the sensitivity by plasticizing the ink layer, and the addition of a surfactant that improves the coatability of the ink layer.

  In addition to these, a lubricant may be added. By adding a lubricant, it is possible to improve the transportability of the ink sheet and to increase the adhesion between the ink layer and the image receiving layer during laser exposure. Examples of the lubricant include the following synthetic waxes.

1) Fatty acid-based wax C8-30 saturated fatty acid: Specific examples include stearic acid, behenic acid, palmitic acid, 12-hydroxystearic acid, azelaic acid and the like. Moreover, metal salts (K, Ca, Zn, Mg, etc.), such as the said fatty acid, are mentioned.

2) Fatty acid ester wax Examples of fatty acid esters include ethyl stearate, lauryl stearate, ethyl behenate, hexyl behenate, behenyl myristate, glycerin ester and the like.

3) Fatty acid amide wax Specific examples of fatty acid amides include stearic acid amide and lauric acid amide.

4) Aliphatic alcohol-based wax Linear saturated aliphatic alcohol having 7 to 29 carbon atoms: Specific examples include lauryl alcohol and stearyl alcohol.

5) Polymer wax Examples include polyethylene having a number average molecular weight of 200 to 10,000.

  Among the synthetic waxes 1) to 5), higher fatty acid amides such as behenic acid, mono higher fatty acid esters of glycerin, stearic acid amide, and lauric acid amide are preferable.

  In addition to the above components, surfactants, inorganic or organic fine particles (metal powder, silica gel, etc.), oils (linseed oil, mineral oil, etc.), thickeners, antistatic agents and the like may be contained.

  Solvents used for preparing the ink layer coating liquid include water, methanol, ethanol, i-propyl alcohol, propyl alcohol, butyl alcohol, methyl ethyl ketone, cyclopentanone, cyclohexanone, propylene glycol monomethyl ether, propylene glycol monoethyl ether Etc. The application / drying can be performed using a normal application / drying method.

  A preferable thickness of the ink layer is 0.2 to 2 μm, and more preferably 0.3 to 1.5 μm. In particular, it has been confirmed that high sensitivity can be obtained when the thickness is 0.8 μm or less. However, since the thin film transferability of the ink layer differs depending on the type of binder and colorant used, the mixing ratio thereof, etc., an optimum film The thickness range is selected depending on the balance between sensitivity and resolution, and other desired image reproduction performance.

(Back coat layer)
A back coat layer can be provided on the surface opposite to the ink layer for the purpose of providing the ink sheet with stable transportability and preventing blocking of the ink layer. Binders used in the back coat layer include gelatin, polyvinyl alcohol, 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, polyester resin, see Patent Document 4, Teflon (R) resin, polyvinyl butyral resin, vinyl chloride resin, polyvinyl acetate, polycarbonate, organic boron compound, aromatic ester General-purpose polymers such as fluorinated polyurethane and polyethersulfone can be used. Using a crosslinkable water-soluble binder as the binder for the backcoat layer is effective in preventing the mat material from falling off and improving the scratch resistance of the backcoat. It is also very effective in preventing blocking during storage. As the crosslinking means, any one or combination of heat, actinic rays, pressure, and the like can be adopted without particular limitation depending on the characteristics of the crosslinking agent to be 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 adhesion to the support.

Further, the back coat layer preferably contains a mat material. As the mat material preferably added to the back coat layer, organic or inorganic fine particles can be used. Examples of the organic mat material include polymethyl methacrylate (PMMA), polystyrene, polyethylene, polypropylene, fine particles of other radical polymerization polymers, fine particles of condensation polymers such as polyester and polycarbonate, and the like. The back coat layer is preferably provided at a weight 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 powdering off of the mat material are likely to occur. In addition, if the coating is applied greatly exceeding 5 g / m ² , the particle size of a suitable mat material becomes very large, resulting in embossing of the ink layer surface by back coating during storage, especially in thermal transfer for transferring a thin ink layer. The recorded image is likely to be missing or uneven. The mat material preferably has a number average particle size 1 to 20 μm larger than the film thickness of only the binder of the backcoat layer. Among the mat members, 1 mg / m ² or more of particles having a particle diameter of 2 μm or more are required, and preferably ² to 600 mg / m ² . This in particular improves foreign matter failures. Further, by using a narrow particle size distribution such that a value σ / rn (= coefficient of variation of the 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, 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 variation coefficient is more preferably 0.15 or less.

An antistatic agent is preferably added to the backcoat layer in order to prevent adhesion of foreign matters due to frictional charging with the transport roll during sheet supply. Examples of the antistatic agent include a cationic surfactant, an anionic surfactant, a nonionic surfactant, a polymer antistatic agent, conductive fine particles, “11290 Chemical Products”, Chemical Industry Daily, 875-876. The compounds described on pages etc. are widely used. As the antistatic agent that can be used in combination with the backcoat layer, 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. In particular, it is preferable to use conductive fine particles because the antistatic agent is not dissociated from the backcoat layer and a stable antistatic effect can be obtained regardless of the environment. Specific examples include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , MgO, BaO, CoO, CuO, Cu ₂ O, CaO, SrO, BaO ₂ , PbO, PbO ₂ , MnO ₃ , MoO ₃ , SiO ₂ , ZrO ₂ , Ag ₂ O, Y ₂ O ₃ , Bi ₂ O ₃ , Ti ₂ O ₃ , Sb ₂ O ₃ , Sb ₂ O ₅ , K ₂ Ti ₆ O ₁₃ , NaCaP ₂ O ₁₈ , Oxides such as MgB ₂ O ₅ ; sulfides such as CuS and ZnS; carbides such as SiC, TiC, ZrC, VC, NbC, MoC, WC; Si ₃ N ₄ , TiN, ZrN, VN, NbN, Cr ₂ N Nitrides such as TiB ₂ , ZrB ₂ , NbB ₂ , TaB ₂ , CrB, MoB, WB, LaB _5, etc .; TiSi ₂ , ZrSi ₂ , NbSi ₂ , TaSi ₂ , CrSi ₂ , MoSi ₂ , WSi ₂ silicide etc.; BaCO _3, CaCO ₃ SrCO _3, BaSO _4, CaSO ₄ and the like metal _{salts; SiN 4 -SiC, 9Al 2 O} 3 -2B 2 O 3 composite of the like, even if alone or in combination of two or more of these one Good. Of these, SnO ₂ , ZnO, Al ₂ O ₃ , TiO ₂ , In ₂ O ₃ , MgO, BaO and MoO ₃ are preferred, SnO ₂ , ZnO, In ₂ O ₃ and TiO ₂ are more preferred, and SnO ₂ is preferred. Particularly preferred.

  In addition, various activators, mold release agents such as silicone oil, fluorine-based resins, and the like can be added to the back coat layer in order to impart coatability and mold release properties. The back coat layer is particularly preferable when the softening point measured by TMA of the cushion layer and the image receiving layer is 70 ° C. or less.

  The back coat layer may be composed of two layers. In this case, the ratio B / A between the mass A of the antistatic agent contained in the lower back layer and the mass B of the antistatic agent contained in the upper backcoat layer is preferably less than 0.3. When B / A is 0.3 or more, there is a tendency that slipperiness and powder fall off of the back coat layer are deteriorated. The ratio of the layer thickness of the upper layer and the lower layer is preferably 1: 2 to 5: 1.

(Cushion layer)
For the ink sheet, a cushion layer may be provided on the support, or a support having a cushioning property may be used. In this way, the adhesion between the ink sheet and the image receiving sheet is improved, the area of image defects due to dust entering between them is reduced, and the effect of increasing the sensitivity is also obtained. Further, by providing an adhesive cushion layer, an ablation suppressing effect can be obtained when a photothermal conversion layer is laminated on the layer. Specifically, the same cushion layer as that in the image receiving sheet can be used.

<Image forming method>
Next, the image forming method of the present invention will be described. The image formation of the present invention consists of two processes. That is,
1) A process of closely attaching an image receiving sheet and an ink sheet, and transferring an image like an image from the ink sheet side by laser exposure. 2) Repeating the above processes a plurality of times to form a color image on the image receiving sheet, and the color image surface. And the final recording medium facing each other, applying heat and / or pressure to bond the image receiving sheet and the final recording medium, and then peeling the image receiving sheet to transfer the image to the final recording medium together with the image receiving layer. is there.

  As an example, an image receiving sheet and an image forming ink sheet are wound around an exposure drum in order and held by adhesion under reduced pressure, and the image data is supported from the back surface of the ink sheet (back coat layer application surface side) while rotating the drum. By irradiating a laser beam, an image is thermally transferred from an ink sheet to an image receiving sheet. After the exposure, the ink sheet is peeled off, the image surface of the image-receiving image-formed sheet and the final transfer medium (for example, printing paper) are superimposed, laminated with a heated roll, and then peeled off from the image-receiving sheet on the final recording medium. An image is formed, and an image recorded material that is very similar to a printed material can be obtained.

Examples of the light source of the image recording laser used in the present invention include a semiconductor laser, a YAG laser, a carbon dioxide gas laser, and a helium neon laser. Among semiconductor lasers, it is preferable to use a so-called single mode laser diode, as it is easy to narrow the 1 / e ² diameter to several to several tens of μm at the focal point without significantly reducing the optical efficiency.

  Examples of laser scanning methods include cylindrical outer surface scanning, cylindrical inner surface scanning, and planar scanning. In the cylindrical outer surface scanning, laser exposure is performed while rotating a drum around which the recording material is wound, the rotation of the drum is used as main scanning, and the movement of laser light is used as sub scanning. In cylindrical inner surface scanning, a recording material is fixed to the inner surface of the drum, a laser beam is irradiated from the inside, and a main scanning is performed in the circumferential direction by rotating a part or all of the optical system. Sub scanning is performed in the axial direction by linearly moving all of them in parallel with the drum axis. In plane scanning, a laser beam main scan is performed by combining a polygon mirror, a galvanometer mirror, and an fθ lens, and a sub-scan is performed by moving a recording medium. Cylindrical outer surface scanning and cylindrical inner surface scanning are easier to increase the accuracy of the optical system and are suitable for high-density recording. In the case of so-called multi-channel exposure in which a plurality of light emitting elements are used simultaneously, cylindrical outer surface scanning is most suitable. Also, when using a YAG laser or the like having a large exposure output, it is difficult to significantly increase the drum rotation speed in the cylindrical outer surface scanning, so that the cylindrical inner surface scanning is suitable. Examples of light sources other than lasers include light emitting diodes (LEDs). LEDs and semiconductor lasers are easy to use as an array in which a plurality of light emitting elements are integrated. The laser beam is preferably irradiated under conditions such that the beam diameter on the photothermal conversion layer is in the range of 5 to 50 μm (especially 6 to 30 μm), and the scanning speed is 1 m / second or more (particularly 3 m / second or more). ) Is preferable.

  The exposure apparatus used in the present invention is preferably equipped with a multichannel exposure head. The multi-channel arrangement is preferably two-dimensional. The two-dimensional array uses a plurality of laser beams when recording by laser irradiation, and the spot array of these laser beams is composed of a plurality of columns along the main scanning direction and a plurality of rows along the sub-scanning direction. Is a planar arrangement.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, the embodiment of this invention is not limited to these. Unless otherwise specified, “part” in the examples represents “part by mass” and “%” represents “% by mass”.

Example 1
<Preparation of ink sheet Y1>
A transparent PET film having a thickness of 38 μm (manufactured by Mitsubishi Chemical Polyester Film Co., Ltd .: T100 # 38) is used as a support, and then a release layer coating solution having the following composition is applied and dried with a reverse roll coater. A release layer of ³ g / m ² was formed.
(Release layer coating solution)
Release layer binder liquid * 22.9 parts Crosslinking agent (Sumitex Resin M-3: manufactured by Sumitomo Chemical Co., Ltd.) 0.2 parts Pure water 69.2 parts i-Propyl alcohol 7.7 parts * Release layer binder liquid Polyvinyl 9.5 of alcohol (GOHSENOL EG-30: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
% Aqueous solution 97.2 parts Crosslinking accelerator (Sumitex Accelerator ACX: manufactured by Sumitomo Chemical Co., Ltd.)
1.3 parts Fluorine-based resin (Unidyne TG-810: manufactured by Daikin Industries, Ltd.) 0.3 parts Pure water 1.2 parts On the release layer, a yellow ink layer coating solution 1 having the following composition is formed by wire bar coating. Application and drying were performed to form an ink layer having a drying weight of 0.65 g / m ² .
(Yellow ink layer coating solution 1)
Yellow pigment dispersion (10 parts of Seika First Yellow H-7055 dispersed in MEK 88 parts by 2 parts of Ajisper PB822: Ajinomoto Fine Techno Co.)
18.2 parts Styrene resin (Haimar ST-95: manufactured by Sanyo Chemical Industries, Ltd.) 5.0 parts Acrylic resin (Dianar BR-102: manufactured by Mitsubishi Rayon Co., Ltd.) 0.4 parts Styrenic elastomer (Kraton D-1101CU: Kraton) 0.2 parts Rosin ester (KE-311: supra) 1.4 parts Surfactant (Megafac F-178K: Dainippon Ink & Chemicals, Inc.) 0.1 part Methyl ethyl ketone (MEK) 11.5 parts Cyclohexanone 64.5 parts Photothermal conversion layer coating solution 1 having the following composition is applied and dried on the yellow ink layer by wire bar coating, and the photothermal conversion with a dry weight of 0.73 g / m ² is applied. A layer was formed.
(Photothermal conversion layer coating solution 1)
Polyvinyl alcohol (Gosenol EG-30: supra) 4.0 parts Carbon black dispersion (CAB-O-JET300: manufactured by CABOT) 13.5 parts Boric acid 0.2 parts Surfactant (Factent 251: manufactured by Neos) ) 0.1 part pure water 63.4 parts i-propyl alcohol 18.8 parts On the other hand, a transparent PET film (Mitsubishi Chemical Polyester Film Co., Ltd .: T100 # 75) with a thickness of 75 μm was used as a support and a back coat having the following composition The layer coating solution 1 was applied by wire bar coating to form a backcoat layer having a drying weight of 0.65 g / m ² .
(Backcoat layer coating solution 1)
Polyvinyl alcohol (GOHSENOL EG-05: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) 4.7 parts Antistatic agent (Efcol 214: manufactured by Matsumoto Yushi Seiyaku Co., Ltd.) 1.5 parts Matt material (PMMA particles having a volume average particle size of 5.6 μm) 57 parts aqueous solution) 0.6 part Fluorine-based resin (Unidyne TG-810: supra) 2.0 parts Surfactant (phthalent 251: supra) 0.1 part Pure water 81.3 parts i-propyl alcohol 9 .4 parts A cushion layer coating solution 1 having the following composition was applied to the back surface of the back coat layer by wire bar coating to form a cushion layer having a dry weight of 7 g / m ² .
(Cushion layer coating solution 1)
Styrene elastomer (Kraton G1657: manufactured by Kraton Polymer Japan) 10.0 parts Rosin ester (Superester A-100: manufactured by Arakawa Chemical Industries) 4.3 parts Methyl ethyl ketone 17.1 parts Toluene 68.6 parts Next, The light-to-heat conversion layer of each sheet provided with a yellow ink layer and a light-to-heat conversion layer was combined with the cushion layer by roll touch, and then the release layer film was peeled off to obtain an ink sheet Y1. .

<Preparation of ink sheet M1>
An ink sheet M1 was obtained in the same manner as the production of the ink sheet Y1, except that the yellow ink layer coating liquid 1 was changed to the magenta ink layer coating liquid 1 having the following composition. The drying amount of the magenta ink layer coating liquid 1 was 0.67 g / m ² .
(Magenta ink layer coating solution 1)
Magenta pigment dispersion (15 parts of Brilliant Carmine 6B was added to Azisper PB822:
13.9 parts styrene resin (Heimer ST-95: supra) 4.6 parts acrylic resin (Dianar BR-102: supra) 0. 4 parts Styrenic block copolymer (Kraton D-1101CU: supra) 0.2 parts Rosin ester (KE-311: supra) 1.4 parts Surfactant (Megafac F-178K: supra) 0. 1 part Methyl ethyl ketone 16.7 parts Cyclohexanone 64.0 parts <Preparation of ink sheet C1>
An ink sheet C1 was obtained in the same manner as in the production of the ink sheet Y1, except that the yellow ink layer coating liquid 1 was changed to the cyan ink layer coating liquid 1 having the following composition. The dry weight of the cyan ink layer coating solution 1 was 0.70 g / m ² .
(Cyan ink layer coating solution 1)
30 parts of cyan pigment dispersion (phthalocyanine blue PB15: 3 was added to 5 parts of dispersant with ME
5.2 parts Styrene resin (Heimer ST-95: supra) 5.7 parts Acrylic resin (Dianar BR-102: supra) 0.4 part Styrenic elastomer (Kraton D-1101CU) : Supra) 0.3 parts Rosin ester (KE-311: supra) 1.4 parts Surfactant (Megafac F-178K: supra) 0.1 part methyl ethyl ketone 24.1 parts cyclohexanone 64.1 parts < Preparation of ink sheet K1>
An ink sheet was prepared in the same manner as the ink sheet Y1, except that the yellow ink layer coating liquid 1 was changed to the black ink layer coating liquid 1 having the following composition and the photothermal conversion layer coating liquid 1 was changed to the photothermal conversion layer coating liquid 2 having the following composition. K1 was obtained. The dry amount of the black ink layer coating solution 1 was 0.87 g / m ² , and the dry amount of the conversion layer coating solution 2 was 0.73 g / m ² .
(Black ink layer coating solution 1)
Black pigment dispersion (25 parts of carbon black dispersed in 70 parts of MEK with 5 parts of dispersant) 8.0 parts Cyan pigment dispersion (supra) 1.1 parts Violet pigment dispersion (10 parts of dioxazine violet) MEK with 5 parts of dispersant
1.5 parts Styrene resin (Heimer ST-95: supra) 6.2 parts Acrylic resin (Dianar BR-85: manufactured by Mitsubishi Rayon Co., Ltd.) 1.1 parts Styrenic elastomer (Kraton D) -1117P: manufactured by Kraton Polymer Japan) 0.2 parts Rosin ester (KE-311: supra) 1.4 parts Surfactant (Megafac F-178K: supra) 0.1 part Methyl ethyl ketone 19.2 parts cyclohexanone 62.6 parts (photothermal conversion layer coating solution 2)
Polyvinyl alcohol (GOHSENOL EG-30: supra) 3.7 parts Carbon black dispersion (CAB-O-JET300: supra) 14.3 parts Boric acid 0.2 part Surfactant (phthalent 251: supra) 0 .1 part Pure water 62.9 parts i-Propyl alcohol 18.8 parts <Preparation of image-receiving sheet 1>
A backcoat layer coating solution 1 having the following composition was applied to one side of a white PET film (U51L74: manufactured by Teijin Ltd.) having a thickness of 100 μm and dried to provide a backcoat layer. Cushion layer coating solution 1 is applied and dried to provide a cushion layer. On the cushion layer, intermediate layer coating solution 1 having the following composition is applied and dried to provide an intermediate layer, and image receiving layer coating solution having the following composition is provided on the intermediate layer. The image receiving sheet 1 of the present invention was obtained by coating and drying 1 to provide an image receiving layer. In addition, application | coating of each layer was performed using the wire bar. The drying conditions and film thickness of each layer are as follows.

Back coat layer: 100 ° C., 1 minute, film thickness after drying 3 μm
Cushion layer: 100 ° C., 5 minutes, film thickness after drying 15 μm
Intermediate layer: 80 ° C., 1 minute thickness after drying 1.5 μm
Image receiving layer: 80 ° C., 1 minute, film thickness after drying 2 μm
(Backcoat layer coating solution 1)
Polyester resin (Byron 200: manufactured by Toyobo Co., Ltd.) 11.5 parts Matt material (MX-1000: manufactured by Soken Chemical Co., Ltd.) 0.4 parts Carbon black dispersion (MHI Black # 273: manufactured by Mikuni Dye Co., Ltd.) 6.6 parts Cyclohexanone 40 parts Toluene 20 parts Methyl ethyl ketone 25 parts (Cushion layer coating solution 1)
Polyethylene latex (Hitech S-3127: manufactured by Toho Chemical Industry Co., Ltd.) 95 parts Pure water 5 parts (intermediate layer coating solution 1)
Ethyl cellulose (STD10: manufactured by Dow Chemical Co., Ltd.) 8 parts Gas generating substance A 1.5 parts Methanol-modified ethanol 90.5 parts Gas generating substance A: Poly [bis (azidomethyl) oxetane] having a weight average molecular weight of about 4500 (manufactured by Aerojet) ) 5 g was dissolved in 45 g of MEK heated to 60 ° C., 10 g of acetylenedicarboxylic acid was added, and the mixture was heated at 50 ° C. for 10 hours. The resulting solution was rotoevaporated to form a viscous concentrate (residual solvent 3% or less), and a mixed solvent (4 g triethanolamine, 88 g i-propyl alcohol and 175 g pure water) heated to 40 ° C. was added thereto. In addition, redissolved.
(Image-receiving layer coating solution 1)
Acrylic resin latex (Yodosol A5801 manufactured by NSC Japan) 22.0 parts Fluororesin (Unidyne TG810: manufactured by Daikin Industries) 4.4 parts Mat material (MX40S-2: manufactured by Soken Chemical Co., Ltd.) 2.1 parts Pure water 62 .8 parts i-propyl alcohol 8.7 parts <Preparation of image-receiving sheet 2>
An image receiving sheet 2 of the present invention was produced in the same manner as the image receiving sheet 1 except that the intermediate layer coating solution 1 in the image receiving sheet 1 was replaced with the coating solution 2.
(Intermediate layer coating solution 2)
Ethylcellulose (STD10: supra) 8.0 parts Gas generating substance A 1.5 parts Photothermal conversion agent (SDA2864: manufactured by HW SANDS) 1.0 part Methanol-modified ethanol 89.5 parts <Preparation of image receiving sheet 3 >
The image receiving sheet except that the cushion layer coating solution 1 in the image receiving sheet 1 is replaced with the coating solution 2, the intermediate layer coating solution 1 is replaced with the coating solution 3, and the image receiving layer coating solution 1 is replaced with the coating solution 2. In the same manner as in Example 1, an image receiving sheet 3 of the present invention was produced. The thickness of each layer after drying was as follows: cushion layer = 15 μm, intermediate layer = 2 μm, and image receiving layer = 2 μm.
(Cushion layer coating solution 2)
Polyethylene latex (Hitech S-7024: manufactured by Toho Chemical Industry Co., Ltd.) 90 parts Photothermal conversion agent (SDA2864: supra) 1.0 part Pure water 5 parts Methanol-modified ethanol 4 parts (intermediate layer coating solution 3)
Methyl cellulose (SM-15: manufactured by Shin-Etsu Chemical Co., Ltd.) 8.2 parts PMMA particles (MX-300: manufactured by Soken Chemical Co., Ltd., average particle size: 3.05 μm) 2.0 parts Antimony-doped tin oxide sol (SN100D: manufactured by Ishihara Sangyo Co., Ltd.) , 30% active ingredient)
9.3 parts Gas Generating Substance A 1.5 parts Surfactant (Furgent 251: 25% aqueous solution described above) 0.1 part Water 47 parts Methanol-modified ethanol 40 parts (Image-receiving layer coating solution 2)
Acrylic resin (Dianar BR-102: manufactured by Mitsubishi Rayon Co., Ltd.) 20 parts Antistatic agent (Plenact KR9SA: manufactured by Ajinomoto Fine Techno Co., Ltd.) 1.0 part Mat material (Tospearl T-145: manufactured by GE Toshiba Silicone) 0.1 Part Activator (F-178K: supra) 0.1 part Additive (Sumilyzer GS: manufactured by Sumitomo Chemical Co., Ltd.) 0.1 part Methyl ethyl ketone 40 parts Butanol 40 parts <Preparation of image-receiving sheet 4>
A comparative image-receiving sheet 4 was prepared in the same manner as the image-receiving sheet 1 except that the intermediate-layer coating solution 1 in the image-receiving sheet 1 was replaced with the coating solution 4. The film thickness after drying of the intermediate layer was 3 μm, and the film thickness after drying of the image receiving layer was 1.5 μm.
(Intermediate layer coating solution 4)
Ethylcellulose (STD10: supra) 9.5 parts Methanol-modified ethanol 90.5 parts <Formation of image>
Image recording was performed using the four color ink sheets (Y1, M1, C1, K1) and the image receiving sheets 1 to 4. The combinations of the ink sheet and the image receiving sheet are as described in Table 1.

An image was formed on the image-receiving sheet by the following exposure machine, and the image was transferred to Tokishi double-sided art N: 127.9 g / m ² (Mitsubishi Paper Co., Ltd.) using the following laminator. The temperature and humidity during exposure were maintained at 23 ° C. and 50% RH (relative humidity).

Exposure machine: Color Decision II EV-Laser Proofer II (manufactured by Konica Minolta MG)
B2 size specification 2400dpi (dpi is the number of dots per inch or 2.54cm)
Laminator: Color Decision II EV-Laminator II (manufactured by Konica Minolta MG)
Set temperature: upper roll 100 ° C, lower roll 120 ° C
Speed: 7mm / sec
<Evaluation>
The performance of the transferred image was evaluated according to the following criteria.

"sensitivity"
A solid image was output using the ink sheet of each color of YMCK and the image receiving sheet while changing the exposure rotation amount by 10 rpm from 400 to 800 rpm. The solid image transferred onto the paper was measured with a densitometer (D-196 manufactured by GRETAG), and the density of each color was Y ≧ 1.34, M ≧ 1.46, C ≧ 1.53, K ≧ 1. The drum rotation amount range of 88 was defined as sensitivity. The higher the rotation (low energy) side, the higher the sensitivity, and the wider the range, the wider the exposure latitude.

《Image stains》
It was observed with a loupe whether the photothermal conversion layer was attached to the solid image portion of the image transfer product (YMC) used for the sensitivity evaluation. The exposure rotation amount at the following level is shown in the table. It shows that the smaller the exposure rotation amount at each level, the less likely the stain is generated. Note that K is not evaluated because visual judgment is difficult.

○: No deposits △: Slightly string-like deposits are seen ×: Plate-like deposits are seen

  It can be seen that by using the image receiving sheet of the present invention, high sensitivity and suppression of image contamination can be achieved.

Example 2
<Preparation of ink sheet K2>
Corona treatment is applied to one side of 75 μm thick transparent PET (Mitsubishi Chemical Polyester Film Co., Ltd .: T100 # 75), and a back coat first layer coating solution having the following composition is applied and dried to a dry layer thickness of 0.03 μm. Thus, the first backcoat layer was formed.
(Backcoat first layer coating solution)
Aqueous dispersion of acrylic resin (Julimer ET410: manufactured by Nippon Pure Chemicals, 20% by mass)
2.0 parts antistatic agent (tin oxide-antimony oxide aqueous dispersion: average particle size 0.1 μm, 17% by mass)
7.0 parts polyoxyethylene phenyl ether 0.1 part melamine compound (Sumitex Resin M-3: manufactured by Sumitomo Chemical Co., Ltd.)
0.3 parts Pure water A total amount of 100 parts On the back coat first layer, a back coat second layer coating solution having the following composition was applied and dried to a dry layer thickness of 0.03 μm, and the back A second coat layer was formed.
(Backcoat second layer coating solution)
Polyolefin (Chemipearl S-120: Mitsui Petrochemical Co., Ltd.) 3.0 parts Antistatic agent (supra) 2.0 parts Colloidal silica (Snowtex C: Nissan Chemical Industries, Ltd.) 2.0 parts Epoxy compound (Dinacol) EX-614B: manufactured by Nagase Chemicals Co., Ltd.) 0.3 parts Pure water Amount that makes the total 100 parts On the support opposite to the surface on which the backcoat layer is provided, the coating solution 3 for the photothermal conversion layer having the following composition Was coated and dried using a wire bar to form a photothermal conversion layer having an average film thickness of 0.3 μm.
(Coating liquid 3 for photothermal conversion layer)
Infrared absorbing dye (NK-2014: manufactured by Hayashibara Biochemical Laboratories Co., Ltd.) 7.6 parts Polyimide resin (Rika Coat SN-20F: manufactured by Shin Nippon Chemical Co., Ltd.) 29.3 parts Exxon naphtha 5.8 parts Surfactant (Megafac) F-176PF: manufactured by Dainippon Ink & Chemicals, Inc.) 0.5 part N-methylpyrrolidone 1500 parts methyl ethyl ketone 360 parts Matting agent dispersion * 14.1 parts * Preparation of matting agent dispersion: The following matting material composition and diameter 2 mm 30 parts of the glass beads were put in a 200 ml polyethylene container and dispersed for 2 hours with a paint shaker (manufactured by Toyo Seiki Co., Ltd.) to obtain a dispersion of silica fine particles.
(Matting agent composition)
True spherical silica particles (Seahoster KE-P150: manufactured by Nippon Shokubai Co., Ltd., average particle size 1.5 μm
m) 10 parts Dispersant polymer (Johncrill 611: manufactured by Johnson Polymer Co., Ltd.) 2 parts Methyl ethyl ketone 16 parts N-methylpyrrolidone 64 parts In order to prepare a black ink layer coating solution, the following components are put in a kneader mill, and a small amount A pre-dispersion treatment was performed by applying a shearing force while adding the solvent. A solvent was further added to the dispersion to prepare a composition having the following composition, and sand mill dispersion was performed for 2 hours to obtain a pigment dispersion mother liquor.
(Black pigment dispersion mother liquor)
[Composition 1]
Polyvinyl butyral (ESREC B BL-SH: manufactured by Sekisui Chemical Co., Ltd.) 12.6 parts Carbon black (Mitsubishi Carbon Black # 5: manufactured by Mitsubishi Chemical Corporation) 4.5 parts Dispersing aid (Solsperse S-20000: manufactured by ICI) 0.8 part propyl alcohol 79.4 parts [Composition 2]
Polyvinyl butyral (ESREC B BL-SH: supra) 12.6 parts Carbon black (Mitsubishi Carbon Black MA100: manufactured by Mitsubishi Chemical Corporation) 10.5 parts Dispersing aid (Solsperse S-20000: supra) 0.8 parts Propyl Alcohol 79.4 parts On the surface of the light-to-heat conversion layer, the following black ink coating solution 2 was applied and dried with a wire bar to form a black ink layer having an average film thickness of 0.60 μm. Through the above steps, an ink sheet K2 was obtained.
(Black ink layer coating solution 2)
Black pigment dispersion mother liquor (Composition 1: Composition 2 = 70 parts: 30 parts) 185.7 parts Polyvinyl butyral (ESREC B BL-SH: supra) 11.9 parts Stearic acid amide (Neutron 2: Nippon Seika Co., Ltd.) 1.7 parts behenamide (diamond BM: manufactured by Nippon Kasei Co., Ltd.) 1.7 parts lauric acid amide (diamond Y: manufactured by Nippon Kasei Co., Ltd.) 1.7 parts palmitic acid amide (diamond KP: Nippon Kasei) 1.7 parts erucamide (Diamid L-200: manufactured by Nippon Kasei Co., Ltd.) 1.7 parts oleic acid amide (Diamid O-200: manufactured by Nippon Kasei Co., Ltd.) 1.7 parts Rosin ester (KE-) 311: Arakawa Chemical Industries Ltd.) 11.4 parts Surfactant (Megafac F-176PF: supra) 2.1 parts Inorganic pigment (MEK-ST: Nissan Chemical Industries Ltd.) 7.1 parts Russia pill alcohol 1050 parts Methyl ethyl ketone 295 parts <Preparation of the ink sheet Y2>
In the preparation of the ink sheet K2, an ink sheet Y2 was prepared in the same manner as the ink sheet K2, except that the yellow ink layer coating liquid 2 having the following composition was used instead of the black ink layer coating liquid 2. The thickness of the ink layer of the obtained ink sheet Y2 was 0.42 μm.
(Yellow pigment dispersion mother liquor)
[Composition 1]
Polyvinyl butyral (ESREC B BL-SH: supra) 7.1 parts Yellow pigment (Novoperm Yellow P-HG: manufactured by Clariant Japan Co.) 12.9 parts Dispersing aid (Solsperse S-20000: supra) 0.6 parts Propyl alcohol 79.4 parts [Composition 2]
Polyvinyl butyral (ESREC B BL-SH: supra) 7.1 parts Yellow pigment (Novoperm Yellow M2R 70: manufactured by Clariant Japan) 12.9 parts Dispersing aid (Solsperse S-20000: supra) 0.6 parts 79.4 parts of propyl alcohol (yellow ink layer coating solution 2)
Yellow pigment-dispersed mother liquor (Composition 1: Composition 2 = 95 parts: 5 parts) 126 parts Polyvinyl butyral (ESREC B BL-SH: supra) 4.6 parts stearamide (neutron 2: supra) 0.7 Part behenamide (diamond BM: supra) 0.7 part lauric acid amide (diamond Y: supra) 0.7 part palmitic acid amide (diamit KP: supra) 0.7 part erucamide (Diamid L-200: supra) 0.7 part Oleic acid amide (Diamid O-200: supra) 0.7 part Surfactant (Chemistat 1100: Sanyo Chemical Industries, Ltd.) 0.4 part Rosin ester (KE-311: supra) 2.4 parts Surfactant (Megafac F-176PF: supra) 0.8 part propyl alcohol 793 parts methyl ethyl ketone 198 parts Production of sheet M2>
Ink sheet M2 was prepared in the same manner as ink sheet K2, except that magenta ink layer coating liquid 2 having the following composition was used instead of black ink layer coating liquid 2 in the preparation of ink sheet K2. The thickness of the ink layer of the obtained ink sheet M2 was 0.38 μm.
(Magenta pigment dispersion mother liquor)
[Composition 1]
Polyvinyl butyral (Denka Butyral # 2000-L: manufactured by Denki Kagaku Kogyo Co., Ltd.)
12.6 parts Magenta Pigment (Symular Brilliant Carmine 6B-22)
9: manufactured by Dainippon Ink & Chemicals, Inc.) 15.0 parts Dispersing aid (Solsperse S-20000: supra) 0.6 parts propyl alcohol 80.4 parts [Composition 2]
Polyvinyl butyral (Denka butyral # 2000-L: supra) 12.6 parts Magenta pigment (Lionol Red 6B-4290G: manufactured by Toyo Ink Co., Ltd.)
15.0 parts Dispersion aid (Solsperse S-20000: supra) 0.6 parts Propyl alcohol 79.4 parts (magenta ink layer coating solution 2)
Magenta pigment dispersion mother liquor (Composition 1: Composition 2 = 95 parts: 5 parts) 163 parts Polyvinyl butyral (Denkabutyral # 2000-L: supra) 4.0 parts Stearic acid amide (neutron 2: supra) 0 parts Behenic acid amide (diamond BM: supra) 1.0 part Lauric acid amide ("Diamid Y: supra" 1.0 part Palmitic acid amide (diamond KP: supra) 1.0 part Erucic acid Amide (Diamindo L-200: supra) 1.0 part Oleic acid amide (Diamid O-200: supra) 1.0 part Surfactant (Chemistat 1100: supra) 0.7 part Rosin ester (KE- 311: Ibid.) 4.6 parts Pentaerythritol tetraacrylate (NK ester A-TMMT: Shin-Nakamura Chemical Co., Ltd.) 2.5 parts Surfactant (Megapha F-176PF: <Preparation of Ink Sheet C2> supra) 1.3 parts propyl alcohol 848 parts Methyl ethyl ketone 246 parts
An ink sheet C2 was prepared in the same manner as the ink sheet K2 except that the cyan ink layer coating solution 2 having the following composition was used instead of the black ink layer coating solution 2 in the production of the ink sheet K2. The thickness of the ink layer of the obtained ink sheet C2 was 0.45 μm.
(Cyan pigment dispersion mother liquor)
[Composition 1]
Polyvinyl butyral (ESREC B BL-SH: supra) 12.6 parts Cyanine pigment (Cyanine Blue 700-10FG: manufactured by Toyo Ink Co., Ltd.)
15.0 parts Dispersing aid (PW-36: Enomoto Kasei Co., Ltd.) 0.8 parts propyl alcohol 110 parts [Composition 2]
Polyvinyl butyral (ESREC B BL-SH: supra) 12.6 parts Cyan pigment (Lionol Blue 7027: manufactured by Toyo Ink Co., Ltd.) 15.0 parts Dispersing aid (PW-36: supra) 0.8 parts Propyl alcohol 110 parts (Cyan ink layer coating solution 2)
Cyan pigment-dispersed mother liquor (Composition 1: Composition 2 = 90 parts: 10 parts) 118 parts Polyvinyl butyral (ESREC B BL-SH: supra) 5.2 parts Inorganic pigment (MEK-ST: supra) 1.3 parts Stearic acid amide (Neutron 2: supra) 1.0 part Behenamide (diamond BM: supra) 1.0 part Lauric acid amide (diamond Y: supra) 1.0 part Palmitic acid amide (diamond) KP: supra) 1.0 part erucic acid amide (Diamid L-200: supra) 1.0 part oleic acid amide (Diamid O-200: supra) 1.0 part Rosin ester (KE-311: Supra) 2.8 parts pentaerythritol tetraacrylate (NK ester A-TMMT: supra)
1.7 parts Surfactant (Megafac F-176PF: supra) 1.7 parts Propyl alcohol 890 parts Methyl ethyl ketone 247 parts <Preparation of image receiving sheet 5>
On one side of a 130 μm thick white void PET film support (Lumirror # 130E58: manufactured by Toray Industries, Inc.), the following cushion layer coating solution 3 was applied and dried to form a cushion layer having a layer thickness of about 20 μm. On the same layer, the following image-receiving layer coating solution 3 was applied and dried to form an image-receiving layer having a layer thickness of about 2 μm to obtain an image-receiving sheet 5 of the present invention.
(Cushion layer coating solution 3)
20.0 parts of vinyl chloride-vinyl acetate copolymer (MPR-TSL: manufactured by Nissin Chemical Industry Co., Ltd.) Plasticizer (Paraplex G-40: manufactured by CP.HALL.COMPANY)
10.0 parts Surfactant (Megafac F-177: manufactured by Dainippon Ink & Chemicals, Inc.) 0.5 part Antistatic agent (SAT-5 Super (IC): manufactured by Nippon Pure Chemicals Co., Ltd.) 0.3 part Poly [ Bis (azidomethyl) oxetane] (Mw: 4500, manufactured by Aerojet)
3 parts Methyl ethyl ketone 60 parts Toluene 10 parts N, N-dimethylformamide 3 parts (Image-receiving layer coating solution 3)
Polyvinyl butyral (ESREC B BL-1: manufactured by Sekisui Chemical Co., Ltd.) 17 parts Styrene / maleic acid half ester (Oxylac SH-128: manufactured by Nippon Shokubai Co., Ltd.)
63 parts Antistatic agent (Chemist 3033: Sanyo Chemical Industries) 16 parts Surfactant (Megafac F-176PF: Dainippon Ink & Chemicals) 1.2 parts Propyl alcohol 570 parts Methanol 1200 parts 1-Methoxy- 2-Propanol 520 parts <Preparation of image receiving sheet 6>
An image receiving sheet 6 of the present invention was produced in the same manner as the image receiving sheet 5 except that the cushion layer coating solution 3 in the image receiving sheet 5 was replaced with the coating solution 4.
(Cushion layer coating solution 4)
20.0 parts of vinyl chloride-vinyl acetate copolymer (MPR-TSL: manufactured by Nissin Chemical Industry Co., Ltd.) Plasticizer (Paraplex G-40: manufactured by CP.HALL.COMPANY)
10.0 parts Surfactant (Megafac F-177: manufactured by Dainippon Ink & Chemicals, Inc.) 0.5 part Antistatic agent (SAT-5 Super (IC): manufactured by Nippon Pure Chemicals Co., Ltd.) 0.3 part Poly [ Bis (azidomethyl) oxetane] (Mw: 4500, manufactured by Aerojet)
3 parts Photothermal conversion agent (SDA7950: manufactured by HW SANDS) 1.5 parts Methyl ethyl ketone 60 parts Toluene 10 parts N, N-dimethylformamide 3 parts <Preparation of image receiving sheet 7>
A comparative image receiving sheet 7 was prepared in the same manner as the image receiving sheet 5 except that the cushion layer coating solution 3 in the image receiving sheet 5 was replaced with the coating solution 5.
(Cushion layer coating solution 5)
20.0 parts of vinyl chloride-vinyl acetate copolymer (MPR-TSL: manufactured by Nissin Chemical Industry Co., Ltd.) Plasticizer (Paraplex G-40: manufactured by CP.HALL.COMPANY)
10.0 parts Surfactant (Megafac F-177: manufactured by Dainippon Ink & Chemicals, Inc.) 0.5 part Antistatic agent (SAT-5 Super (IC): manufactured by Nippon Pure Chemical Industries, Ltd.) 0.3 part Methyl ethyl ketone 60 Part Toluene 10 parts N, N-dimethylformamide 3 parts <Image formation>
Images were formed under the same conditions as in Example 1 using four color ink sheets (Y2, M2, C2, K2) and image receiving sheets 5, 6, and 7.

<Evaluation>
The performance of the transferred image was evaluated according to the following criteria.

"sensitivity"
Drum rotation amount in which the solid density (Y ≧ 1.38, M ≧ 1.53, C ≧ 1.60, K ≧ 1.90) of the image transfer product obtained in the same manner as in Example 1 is stably obtained. The range was defined as sensitivity.

《Color reproducibility》
The ink layer side of the ink sheet of Example and Comparative Example and the image receiving layer side of the image receiving sheet were heated and laminated, the ink layer was thermally transferred to the image receiving layer, and the image was transferred to the same art paper as in Example 1. The hue (L ^* , a ^* , b ^* ) of the portion where the ink layer exists is measured with a colorimeter (SPM100 manufactured by GRETAG). This is hue 1. Subsequently, the hue of the solid portion of the image transfer product used for the sensitivity evaluation (the same drum rotation range as the sensitivity) was also measured. This was designated as hue 2, and the difference between hue 1 and hue 2 was designated as ΔE. Since hue 2 takes a different value depending on the drum rotation amount (that is, exposure energy), ΔE also has a certain width, but only the maximum value is described in this evaluation. The smaller the value of ΔE, the smaller the color variation and the higher the color reproducibility.

  By using the image receiving sheet of the present invention, an image with high sensitivity and high color reproducibility can be obtained. This image is suitable as a color proof.

Claims (5)

An image receiving sheet having at least a cushion layer and an image receiving layer on a support, wherein the adjacent layer on the support side of the image receiving layer contains a substance that generates a gas by laser exposure. The image-receiving sheet according to claim 1, wherein the support-side adjacent layer of the image-receiving layer containing a substance that generates gas by laser exposure or the support-side adjacent layer of the adjacent layer contains a photothermal conversion substance. 3. The image receiving sheet according to claim 1, wherein the gas generated by the laser exposure is nitrogen. The image receiving sheet according to any one of claims 1 to 3, wherein the support layer side adjacent layer of the image receiving layer contains a mat material. A thermal transfer ink sheet having at least a photothermal conversion layer and an ink layer on a support and the image receiving sheet according to any one of claims 1 to 4, and irradiating a laser beam to the ink layer of the thermal transfer ink sheet. An image forming method comprising recording an image by transferring a laser beam irradiation region onto an image receiving layer of the image receiving sheet.