JPH11180059A - Thermal-transfer ink ribbon, image-receiving sheet material, and image formation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high performance thermal-transfer ink ribbon wherein an absolute value for a difference between a dependence of a primary color recording sensitivity on temperature and humidity (a difference between the primary color recording sensitivity under a high temperature and a high humidity, and the primary color recording sensitivity under a low temperature and a low humidity), and a dependence of a secondary color recording sensitivity on temperature and humidity (a difference between the secondary color recording sensitivity under a high temperature and a high humidity, and the secondary color recording sensitivity under a low temperature and a low humidity), is small, and a color balance is excellent. SOLUTION: This thermal-transfer ink ribbon is used for an image formation wherein from a thermal-transfer ink ribbon having a heat-transfer ink layer containing a coloring agent and a binder, on a supporting body, the thermal-transfer ink layer is heat-transferred onto an image receiving sheet material having an image receiving layer on a supporting body, and a difference between a moisture content of the thermal-transfer ink layer and a moisture content of the image receiving layer at 30 deg.C and a humidity of 70% RH, is 1.5% or lower. In this case, a configuration wherein the thermal transfer ink layer contains 30-70 wt.% of the coloring agent, and 30-70 wt.% of the binder, and the binder is an amorphous heat-softening resin of which the softening point is 40-150 deg.C, is preferable.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer ink ribbon, an image receiving sheet material and an image forming method which are suitable for forming a color image or the like by thermally transferring a thermal transfer ink layer onto an image receiving sheet material.

[0002]

2. Description of the Related Art In recent years, with the progress of OA, copiers and printers using various recording systems such as an electrophotographic system, an ink jet system, and a thermal transfer recording system have been used in accordance with their respective applications. In the image formation using these, usually, a composition containing a coloring material is melted, or the coloring material is evaporated or sublimated to cause adhesion, adsorption, dyeing, or the like, so that it is formed on a recording medium such as paper or a film sheet. To form an image.

Among them, the thermal transfer recording method has advantages such as easy operation and maintenance, downsizing of the apparatus and cost reduction. In the thermal transfer recording method, a transfer sheet having a heat-meltable ink layer on a support is heated imagewise (imagewise) by a laser or a thermal head, and the meltable ink is transferred to an image-receiving sheet for thermal copy recording. And a heat-diffusion transfer method for melt-transferring to a heat-sensitive transfer recording, and using a heat-sensitive transfer recording ink ribbon having an ink layer containing a heat-diffusible dye (sublimable dye) on a support, using the heat-diffusion transfer image-receiving sheet. There is known a sublimation dye transfer method in which a hydrophilic dye is transferred by diffusion.

In the sublimation type dye transfer system, the gradation of an image can be controlled by changing the transfer amount of the dye in accordance with the change in the thermal energy of the thermal head.
By performing the superimposition recording of magenta and yellow, there is an advantage that a color image having a continuous change in color density can be obtained. However, this method has the following problems. That is, the tone of an image is reproduced mainly by using the density tone, and is suitable for some purposes for consumers who prefer a tone similar to a photograph. It is not suitable for color proofing applications used in the printing field where tone reproduction is performed. Since image formation utilizes dye sublimation, the edge sharpness of the finished image is not sufficient, and the solid density of a thin line is lower than that of a thick line. This is a major problem, especially with regard to the quality of the character image. The durability of the image is low and the development to the field where heat resistance and light resistance are required is limited. Because the thermal recording sensitivity is lower than that of the thermal melting transfer method,
It is not suitable as a high-speed recording material using a high-resolution thermal head expected in the future. The photosensitive material is more expensive than the hot-melt transfer method.

On the other hand, the hot-melt transfer method has advantages over the sublimation dye transfer method, such as high heat sensitivity, excellent light fastness of images, and low cost of materials. There are the following problems. Since gradation reproduction is not density gradation but binary recording, multi-gradation is inferior. Usually, the resolution is reduced due to bleeding during thermal printing because a low melting crystalline wax is used as a binder for the ink layer,
The strength of the transferred image is low. When crystalline waxes are used, it is difficult to obtain a transparent image due to light scattering of the crystalline phase.

In view of such a situation, a new thermosensitive recording method in which a multi-tone pigment color image can be obtained only by the area gradation of binary recording, which is different from the conventional sublimation type dye transfer method and the heat melting type transfer method. As a material, a thermal adhesive thin film peeling method has been proposed. According to the thermal adhesive thin film peeling method, a multi-gradation high-quality color image or a monochrome image is obtained by the pigment transfer method using only the image area gradation, which significantly improves the problem of the conventional thermal transfer recording method. By utilizing the light resistance of color proofs, block originals, or pigments in the printing field as well as consumer printing, it can be applied to the card field, outdoor display field, meter display field, and the like.

Further, the thermal transfer method using only area gradation is excellent in recording sensitivity, dot quality and gradation reproducibility, is free from stickiness, sticking phenomenon and dust defect, and is not dependent on humidity. An image receiving sheet material for thermal transfer recording capable of achieving formation has been proposed.

However, even when the above-described image-receiving sheet material for thermal transfer recording having no humidity dependency is used, an image (secondary color) in which ink layers of a full-color image overlap each other is used.
In some cases, the humidity dependence of the recording sensitivity may occur, and further improvement is desired.

As a method of correcting the humidity dependence of the recording sensitivity, the recording energy of the printer is changed in accordance with the temperature and humidity of the environment where the thermal transfer recording material is used, and the recording sensitivity is adjusted to the temperature and humidity of each environment. As described above, the primary color (when the ink layer is recorded directly on the image receiving sheet) and the secondary color (when an image of a different hue is formed on the previously formed ink layer image) can be considered. If the humidity sensitivity of the recording sensitivity is different, the gradation correction of only the primary color cannot correct the gradation of the entire full-color image including the secondary color, which causes a serious problem in image quality.

[0010]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and achieve the following objects. That is, according to the present invention, the temperature and humidity dependence of the primary color recording sensitivity (difference between the primary color recording sensitivity under high temperature and high humidity and the primary color recording sensitivity under low temperature and low humidity) and the temperature and humidity dependence of the secondary color recording sensitivity ( The absolute value of the difference between the secondary color recording sensitivity under high temperature and high humidity and the secondary color recording sensitivity under low temperature and low humidity) is small (that is, the absolute value of the difference between the two is small).
High performance thermal transfer ink ribbon with excellent color balance,
It is an object to provide an image receiving sheet material and an image forming method.

[0011]

Means for solving the above problems are as follows. That is, <1> from a thermal transfer ink ribbon having a thermal transfer ink layer containing a colorant and a binder on a support, to a thermal transfer ink layer on an image receiving sheet material having an image receiving layer on the support. A thermal transfer ink ribbon used for forming an image for thermally transferring the ink, wherein the difference between the water content of the thermal transfer ink layer and the water content of the image receiving layer at 30 ° C. and 70% RH is 1.5%.
A thermal transfer ink ribbon characterized by the following. <2> The thermal transfer ink layer contains 30 to 70% by weight of the colorant.
And the binder is 30 to 70 wt%, and the binder is an amorphous thermosoftening resin having a softening point of 40 to 150 ° C.
<2> The thermal transfer ink ribbon according to (1). <3> Thermal transfer of the thermal transfer ink layer from a thermal transfer ink ribbon having a thermal transfer ink layer containing a colorant and a binder on a support to an image receiving sheet material having an image receiving layer on the support. An image receiving sheet material used for forming an image, wherein the difference between the water content of the thermal transfer ink layer and the water content of the image receiving layer at 30 ° C. and 70% RH is 1.5% or less. It is an image receiving sheet material. <4> The image receiving layer has one image receiving layer in contact with the support and two image receiving layers formed on the image receiving layer, and the water content of the image receiving layer is the water content of the two image receiving layers. 3>. <5> Thermal transfer of the thermal transfer ink layer from a thermal transfer ink ribbon having a thermal transfer ink layer containing a colorant and a binder on a support to an image receiving sheet material having an image receiving layer on the support The difference between the water content of the thermal transfer ink layer and the water content of the image receiving layer at 30 ° C. and 70% RH is 1.5% or less.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The thermal transfer ink ribbon, the image receiving sheet material and the image forming method using the same according to the present invention will be described in detail below.

(Thermal Transfer Ink Ribbon) The thermal transfer ink ribbon of the present invention has a thermal transfer ink layer on one surface of a support, and if necessary, as another layer, for example, the other of the support. It has a back layer such as a slip layer on the surface.

--- Thermal transfer ink layer-- The thermal transfer ink layer contains a colorant and a binder, and further contains other components as necessary.

-Colorant- The content of the colorant in the thermal transfer ink layer is preferably 30 to 70 wt%, and more preferably 35 to 60 wt%.
More preferably, it is wt%. The content is 30w
If it is less than t%, the thickness of the thermal transfer ink layer for obtaining a predetermined density becomes thick, and in the tone reproducibility based on only the area tone, the shadow portion is easily crushed, and the highlight portion is liable to fly. As a result, while the gradation reproducibility may be inferior, if it exceeds 70 wt%, the quality of the thermal transfer ink layer tends to deteriorate and the abrasion resistance tends to deteriorate.

The particle size of the colorant is 7
It is preferable that 0 wt% or more is 1.0 μm or less.
When the particle size of the colorant is large, the transparency of the overlapping portion of each color during color reproduction is impaired, and it becomes difficult to maintain the relationship between the thickness and the concentration of the thermal transfer ink layer in a good range. Sometimes.

The colorant is not particularly limited and can be appropriately selected from known ones. Examples thereof include carbon black, azo type, phthalocyanine type, quinacridone type, thioindigo type, anthraquinone type and isoindoline type. And the like. These may be used alone or in combination of two or more. Also,
In the present invention, a known dye may be further added for adjusting the hue.

-Binder- The content of the binder in the thermal transfer ink layer is preferably 30 to 70 wt%, and more preferably 40 to 65 wt%.
More preferably, it is wt%. The content is 30w
When the amount is less than t%, the quality of the thermal transfer ink layer tends to deteriorate and the abrasion resistance tends to deteriorate. On the other hand, when the amount exceeds 70 wt%, the thickness of the thermal transfer ink layer for obtaining a predetermined density increases, and only the area gradation is increased. , The shadow portion may be easily crushed, or the highlight portion may easily fly, and as a result, the tone reproducibility may be poor.

As the binder, an amorphous thermosoftening resin is particularly preferably mentioned. The softening point of the amorphous thermosoftening resin is preferably from 40 to 150C. When the softening point of the amorphous thermosoftening resin is less than 40 ° C., the colored ink is coated on a support to form a thermal transfer ink layer,
When a thermal transfer ink ribbon is manufactured, the adhesive resistance of the thermal transfer ink layer may be poor, and when it exceeds 150 ° C., the thermal recording sensitivity of the thermal transfer ink layer may be poor.

Examples of the amorphous thermosoftening resin having a softening point of 40 to 150 ° C. include butyral resin, polyamide resin, polyethyleneimine resin, sulfonamide resin, polyester polyol resin, petroleum resin, styrene, vinyltoluene, Styrene such as α-methylstyrene, 2-methylstyrene, chlorostyrene, vinylbenzoic acid, sodium vinylbenzenesulfonate, aminostyrene and derivatives thereof, homopolymers and copolymers of substituted products, methyl methacrylate, ethyl methacrylate, butyl Methacrylates, methacrylates such as hydroxyethyl methacrylate and methacrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, α-
Acrylic acid esters such as ethylhexyl acrylate and acrylic acid, butadienes, dienes such as isoprene,
Acrylonitrile, vinyl ethers, maleic acid and maleic esters, maleic anhydride, cinnamic acid, vinyl chloride, vinyl acetate and other vinyl monomers alone or copolymers with other monomers and the like. Can be These may be used alone or in combination of two or more. Among these, butyral resin and acrylic resin are particularly preferable from the viewpoint of dispersibility.

-Formation of Thermal Transfer Ink Layer- The thermal transfer ink layer can be formed by applying a thermal transfer ink layer coating solution on the support and drying. The coating liquid for a thermal transfer ink layer is obtained, for example, by dissolving or dispersing the colorant and the binder in a known solvent.

The solvent is not particularly limited and may be appropriately selected from known materials according to the purpose. Examples thereof include alcohols such as methanol, ethanol, n-propyl alcohol and i-propyl alcohol. Solvents, ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, ester solvents such as ethyl acetate, normal propyl acetate and isopropyl acetate, cellosolve solvents such as methyl cellosolve and ethyl cellosolve, and aromatic solvents such as toluene and xylene. No. These may be used alone or in combination of two or more.

The method of dissolving or dispersing is not particularly limited, and a known method can be appropriately employed. For example, the above-mentioned solvent is added to the colorant and dispersed using a ball mill or the like. A method can be adopted.

A release agent or a softener can be suitably added to the coating liquid for the thermal transfer ink layer as other components. In this case, it is advantageous in that the releasability of the thermal transfer ink layer from the support during thermal printing is improved and the thermal sensitivity is improved. The content of the release agent or the softening agent in the thermal transfer ink layer is about 1 to 20 wt% based on the total amount of the thermal transfer ink layer.

Specific examples of the release agent and the softener include higher fatty acids such as palmitic acid and stearic acid, fatty acid metal salts such as zinc stearate, fatty acid esters or partially saponified products thereof, and fatty acids such as fatty acid amides. Derivatives,
Higher alcohols, derivatives such as ethers of polyhydric alcohols, paraffin wax, carnauba wax, montan wax, beeswax, wood wax, candelilla wax and other waxes, having a viscosity average molecular weight of about 1,000 to 10,
About 000 low molecular weight polyethylene, polypropylene,
Polyolefins such as polybutylene, or low molecular weight copolymers of olefins, α-olefins with organic acids such as maleic anhydride, acrylic acid, methacrylic acid, vinyl acetate, low molecular weight oxidized polyolefins, halogenated polyolefins , Lauryl methacrylate, stearyl methacrylate or other methacrylate having a long alkyl side chain, acrylate or acrylate having a perfluoro group, methacrylates alone or in combination with vinyl monomers such as styrenes Coalescing,
Low molecular weight silicone resins such as polydimethylsiloxane and polydiphenylsiloxane, silicone-modified organic substances, etc., and also cationic surfactants such as ammonium salts and pyridinium salts having long-chain aliphatic groups, or similarly long-chain aliphatic groups , A nonionic surfactant, a perfluoro surfactant, and the like. These may be used alone or in combination of two or more.

The coating can be performed according to a known method, for example, using an air doctor coater, a blade coater, a rod coater, a knife coater, a squeeze coater, a reverse roll coater, a bar coater or the like. The drying may be any of natural drying, heat drying, and the like. In the case of the heat drying, the drying is generally performed at 50 to 180 ° C. for about 0.5 to 20 minutes.

The optical density of the thermal transfer ink layer is as follows:
When thermally transferred onto a white support, the higher the reflection density, the better. For example, the reflection density is preferably 1.0 or more.

The thermal transfer ink layer has a thickness of 0.1 mm.
2 to 1.0 μm is preferred. When the thickness is more than 1.0 μm, in the tone reproducibility based on the area tone alone, the shadow portion is easily crushed or the highlight portion is liable to fly, resulting in poor tone reproducibility. Yes, 0.
If it is less than 2 μm, it tends to be difficult to obtain a predetermined concentration.

The main components of the thermal transfer ink layer are the colorant and the binder (amorphous thermosoftening resin), and the ratio of the colorant is higher than that of a conventional wax-melt type thermal transfer ink layer. When it is higher, the viscosity at the time of thermal transfer is 10 ² to 10 ³ cps as compared with the wax-melt type thermal transfer ink layer.
And it is higher than at least 10 ⁴ cps at 150 ° C., so that a thin film peeling development type thermal transfer ink ribbon can be obtained.

In the case of the thermal transfer ink ribbon of the thin film peeling development type, in addition to the effect of thinning the thermal transfer ink layer, while maintaining a high resolution, a wide gradation from a shadow portion to a highlight portion can be obtained. Reproduction can be performed, edge sharpness can be improved, and 100% image transfer can be performed, and uniformity of density between small characters such as four points and solid portions can be realized.

The water content of the thermal transfer ink layer at 30 ° C. and 70% RH is 30% of the image receiving layer described later.
The difference from the water content at 70 ° C. and 70% RH needs to be 1.5% or less, and more preferably 0.5% or less. If the difference in the water content exceeds 1.5%, the absolute value of the difference between the temperature and humidity dependence of the primary color recording sensitivity and the temperature and humidity dependence of the secondary color recording sensitivity increases, and the color balance becomes poor. .

In the present invention, the Karl Fischer method is used as a method for measuring the water content. That is, the sample for measuring the water content (the thermal transfer ink layer and the image receiving layer) is conditioned at a high temperature and a high humidity (30 ° C., 70% RH) for 24 hours or more, and is subjected to a high temperature and a high humidity (30 ° C., 70% RH). The weight of the sample is accurately weighed in ()). Thereafter, the water content (weight) of the sample is determined by a Karl Fischer moisture meter, and the water content / the weight of the sample × 100 is defined as the water content of the sample under high temperature and high humidity. When two or more image receiving layers are provided, the water content of the layer (top layer) to which the thermal transfer ink layer is directly transferred is defined as the water content of the image receiving layer.

-Support-Examples of the material of the support include polyester (polyethylene terephthalate, polyethylene naphthalate, etc.), polycarbonate, polypropylene, polyvinyl chloride, polyimide and the like. Among them, polyester is preferable, and polyethylene terephthalate is more preferable.

The support is not particularly limited, and may be a foam sheet or a laminate of films of different materials. Note that, for example, the back surface of the support may be subjected to a release treatment or the like.

The average thickness of the support is 2 to 8 μm.
m is preferable and 3 to 6 μm is more preferable. If the average thickness is less than 2 μm, deformation of the support due to heating during thermal transfer hinders the transport of the ink ribbon, while if it exceeds 8 μm, the recording sensitivity is significantly reduced.

--Other layers-- In the image formation by the ablation method using a laser beam, an embodiment having a light-to-heat conversion layer and a heat-sensitive peeling layer as other layers is preferable.

Light-to-Heat Conversion Layer The light-to-heat conversion layer is a layer between the support and the thermal transfer ink layer (image forming layer) that absorbs laser light and converts it into heat. The light-to-heat conversion layer generally contains a dye (eg, a pigment) capable of absorbing laser light and a binder. Examples of the dyes (eg, pigments) that can be used include:
Black pigments such as carbon black, macrocyclic compounds such as phthalocyanines and naphthalocyanines that absorb in the visible to near-infrared region, and organic dyes (indolenin dyes etc.) used as laser absorbing materials for high-density laser recording such as optical discs Organic metal compound dyes such as a cyanine dye, anthraquinone dye, an azulene dye, a phthalocyanine dye) and a dithiol nickel complex. In order to increase the recording sensitivity, it is preferable that the light-to-heat conversion layer is as thin as possible. Therefore, it is preferable to use a cyanine dye or a phthalocyanine dye having a large absorption coefficient in a laser light wavelength region.

The material of the binder for the light-to-heat conversion layer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include acrylic acid such as acrylic acid, methacrylic acid, acrylic acid ester, and methacrylic acid ester. Homopolymers or copolymers of system monomers, cellulosic polymers such as methylcellulose, ethylcellulose, cellulose acetate, polystyrene, vinyl chloride-vinyl acetate copolymer, polyvinylpyrrolidone, polyvinylbutyral, vinyl polymers such as polyvinyl alcohol and vinyl compounds Copolymers, polyesters, condensation polymers such as polyamides, rubber-based thermoplastic polymers such as butadiene-styrene copolymers, and polymers obtained by polymerizing and crosslinking photopolymerizable or thermopolymerizable compounds such as epoxy compounds. Can be

The light-to-heat conversion layer comprises a dye (dye or pigment)
And a binder, the weight ratio of the two (dye:
The binder) is preferably 1: 5 to 10: 1, and particularly preferably 1: 3 to 3: 1. If the amount of the binder is too small, the cohesive force of the light-to-heat conversion layer decreases, and when the formed image is transferred to the image receiving sheet, it tends to be easily transferred together, which causes color mixing of the image. If the amount of the binder is too large, it is necessary to increase the thickness of the light-to-heat conversion layer in order to achieve a constant light absorption rate, which tends to cause a decrease in sensitivity.

The thickness of the light-to-heat conversion layer is generally 0.05 to 2 μm, preferably 0.1 to 1 μm.
Further, it is preferable that the light-to-heat conversion layer has a light absorption rate of 70% or more at the wavelength of laser light used for optical recording.

-Heat-sensitive release layer- The heat-sensitive release layer is a layer containing a heat-sensitive material that generates a gas by the action of heat generated in the light-to-heat conversion layer. As the heat-sensitive material, a compound (polymer or low-molecular compound) which decomposes or degrades by heat to generate a gas or absorbs or adsorbs a considerable amount of easily vaporizable gas such as moisture as a characteristic of the material. Compound (polymer or low molecular compound) can be used. These can be used in combination.

Examples of the polymer which decomposes or degrades by heat to generate a gas include self-oxidizing polymers such as nitrocellulose, chlorinated polyolefins, chlorinated rubbers, and the like.
Halogen-containing polymers such as polyvinyl chloride, polyvinyl chloride, and polyvinylidene chloride; acrylic polymers such as polyisobutyl methacrylate in which volatile compounds such as moisture are adsorbed; and ethyl cellulose in which volatile compounds such as water are adsorbed. And natural polymer compounds such as gelatin to which volatile compounds such as cellulose ester and water are adsorbed. Examples of the low molecular weight compound which decomposes or degrades by heat to generate a gas include a compound which generates a gas upon exothermic decomposition such as a diazo compound or an azide compound. The decomposition or alteration of the heat-sensitive material due to heat as described above preferably occurs at 280 ° C. or lower, more preferably 230 ° C. or lower.

In the case where a low molecular compound is used as the heat-sensitive material in the heat-sensitive release layer, it is preferable to combine it with a binder. The binder may be a polymer which itself decomposes or degrades by heat to generate a gas, or may be an ordinary polymer binder having no such properties. When a heat-sensitive low-molecular compound and a binder are used in combination, the weight ratio of the former to the latter is preferably 0.02: 1 to 3: 1,
More preferably, the ratio is 0.05: 1 to 2: 1. The heat-sensitive peeling layer desirably covers the light-to-heat conversion layer over substantially the entire front surface thereof, and has a thickness of 0.03.
１1 μm, preferably 0.05-0.5 μm
Is more preferable.

-Slip layer- As the other layer, for example, a back layer such as a slip layer formed on the surface of the support opposite to the layer on which the thermal transfer ink layer is formed, etc. Is mentioned.
The material of the lubricating layer is not particularly limited and may be appropriately selected from known materials according to purposes.However, the lubricating layer may contain a binder and wax. preferable.

The method for forming the lubricating layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the lubricating layer may be prepared by dissolving the above-mentioned components in a known solvent. Examples of the method include a method of applying a coating liquid on a support and drying the applied liquid.

(Image-Receiving Sheet Material) The image-receiving sheet material of the present invention is provided with at least one or more image-receiving layers on one side of a support, and further has other layers as necessary.

--Support-- A material that is chemically and thermally stable and has flexibility is used as the support. Actinic light transmission may be used if necessary. Specifically, biaxially stretched polyethylene terephthalate film, polyethylene, polyolefins such as polypropylene, polyvinyl chloride, polyvinyl halides such as polyvinylidene chloride, cellulose acetate, nitrocellulose, cellulose derivatives such as cellophane, polyamides, Polystyrene, polycarbonate, polyimides, and optionally paper laminated with a polyethylene film can also be used. Among them, 2 which is excellent in dimensional stability and permeability
An axially stretched polyethylene terephthalate film is particularly preferred.

--Image receiving layer-- The image receiving layer is provided at least one on one surface of the support. The water content of the image receiving layer at 30 ° C. and 70% RH is 30% humidity and 70% RH of the thermal transfer ink layer.
The difference between the RH and the water content needs to be 1.5% or less, and more preferably 0.5% or less.
If the difference in the water content exceeds 1.5%, the absolute value of the difference between the temperature and humidity dependence of the primary color recording sensitivity and the temperature and humidity dependence of the secondary color recording sensitivity increases, and the temperature and humidity dependence increases. And the color balance is not good. In the present invention, the expression “the temperature / humidity dependence is large” means that the absolute value is within 5%.

The image-receiving layer may have a single-layer structure or a laminated structure. In the present invention, a laminated structure is preferable. In this case, a layer in contact with the support (hereinafter, referred to as "image-receiving layer") and A structure comprising a layer provided thereon (hereinafter, referred to as “image receiving two layers”) is preferable. In the case of this preferred structure, it is possible to perform a surface treatment such as a corona discharge treatment or a glow discharge treatment, or provide an undercoat layer or the like in order to improve the adhesive strength between the image receiving layer and the support. The undercoat layer is not particularly limited as long as the adhesive strength between the support and the image receiving layer can be improved, but a silane coupling agent is particularly preferable.

-One image receiving layer- The elastic modulus of the one image receiving layer is 200 kg · f / cm.
It is preferably ² or less. When the one image receiving layer has the elastic modulus within the above range, the image receiving layer has cushioning properties, and the recording sensitivity, dot quality, and gradation reproducibility can be improved. Further, even when dust or the like exists between the thermal transfer ink ribbon and the image receiving sheet material during recording, an image defect hardly occurs. Further, when the image is transferred to the image receiving sheet material and then re-transferred onto printing paper such as paper by heat and pressure, the image receiving layer is embedded according to the unevenness of the paper, so that the adhesion to the paper is improved and the image receiving After peeling off the two layers, an image having a surface gloss similar to that of a printed matter can be obtained without any special treatment such as matting the surface.

Specific examples of the material for the image receiving layer include polyolefins such as polyethylene and polypropylene, ethylene copolymers such as ethylene and vinyl acetate or ethylene and acrylate, polyvinyl chloride, and chlorides such as vinyl chloride and vinyl acetate. From organic polymers such as vinyl copolymers, polyvinylidene chloride, vinylidene chloride copolymers, polyamide resins such as poly (meth) acrylate, copolymerized nylon, N-alkoxymethylated nylon, synthetic rubber and chlorinated rubber You can choose. They are,
One type may be used alone, or two or more types may be used in combination.

In the present invention, among these materials, polyvinyl chloride having a degree of polymerization of 200 to 2,000, a copolymer of vinyl chloride and vinyl acetate, a copolymer of vinyl chloride and vinyl alcohol, Particularly preferred is a copolymer of vinyl acetate and maleic acid. As the reason, polyvinyl chloride and vinyl chloride copolymer are
(1) Almost no stickiness at room temperature, (2) Relatively small elasticity, easy to follow irregularities of transferred image during thermal transfer, (3) Abundant plasticizer with good compatibility (4) Easy control of interlayer adhesion due to the effect of the hydroxyl group or carboxyl group in the copolymer component, and the like.

In the present invention, various polymers, adhesion improvers, surfactants, release agents, etc. are used in the above-mentioned materials from the viewpoint of adjusting the adhesive strength between the support and the two image receiving layers in the image receiving sheet material. Can also be added. For the purpose of lowering the modulus of elasticity, it is also possible to use a tacky polymer together with the above-mentioned materials within a range where tackiness at normal temperature does not occur.

For example, a fluorine-based surfactant or the like can be used in each layer, and the addition reduces the interlayer adhesion, and at the same time improves the wettability between the thermal transfer ink layer and the image receiving layer, thereby improving the dot shape. Will improve. However, if the addition amount is too large, the adhesive force between the thermal transfer ink layer and the image receiving layer is reduced, so that the dot shape is deteriorated. Therefore, the addition amount of the release agent or the surfactant is 0.0001. ~ 5%
Is preferable, and 0.001 to 3% is more preferable. In order to improve the coated surface condition, it is preferable to add a small amount of a surfactant.

When a vinyl chloride resin is used, an organic tin stabilizer such as a butyltin stabilizer or an octyltin stabilizer generally known as a stabilizer for polyvinyl chloride and a vinyl chloride copolymer is used. It is also effective to add.

The thickness of the two image receiving layers is 1 to 60 μm.
m is preferable, and 5 to 30 μm is more preferable. The first
The reason is that when the image transferred on the image receiving sheet material is transferred to a permanent support, the image needs to be thicker than the irregularities on the surface of the permanent support. The second reason is 4
This is because it is necessary to have a thickness that can sufficiently absorb the relief step at the portion where the color images overlap. The third reason is that
This is for obtaining sufficient cushioning properties.

-Image receiving two layers- The image receiving two layers (adhesive layer: layer for receiving a heat transferable image forming layer (thermal transfer ink layer)) will be described. The purpose of the image receiving two layers is to separate the image receiving sheet and the image receiving two layers from each other when peeling the image receiving sheet at the time of retransfer to a permanent support, and to form a thin layer on the image on the permanent support. An object of the present invention is to obtain an image similar to the gloss of an actual printed matter without performing a special matting treatment by using the unevenness of the permanent support, leaving only two image receiving layers, and to improve the scratch resistance of the image. Therefore, when the image receiving layer is composed of one layer, the two image receiving layers are usually formed directly on the support.

The water content of the two image receiving layers at 30 ° C. and 70% RH was 30% humidity and 70% RH of the thermal transfer ink layer.
The difference between the RH and the water content must be 1.5% or less, and more preferably 0.5% or less. If the difference in the water content exceeds 1.5%, the absolute value of the difference between the temperature and humidity dependence of the primary color recording sensitivity and the temperature and humidity dependence of the secondary color recording sensitivity increases, and the color balance becomes poor. .

It is preferable that the two image receiving layers are made of a resin material similarly to the one image receiving layer. Examples of the material for the image receiving two layers include, in addition to various organic high molecular polymers used in the image receiving layer, vinyl acetate copolymer, polyvinyl butyral, alkyl acrylate / acrylamide copolymer, modified polyvinyl alcohol, phenol Resins, epoxy resins, urethane resins, urea resins, melamine resins, alkyd resins, maleic resins, hydroxystyrene copolymers, sulfonamide resins, cellulose resins, ester gums and rosins. Among these, polyvinyl butyral and an alkyl acrylate / acrylamide copolymer are particularly preferred.

To these resins, other adhesion improvers, release agents and surfactants can be added in order to satisfy the relationship of adhesive force at various interfaces. In order to prevent mixing between the image receiving layer and the image receiving two layers due to penetration into the lower layer of the coating solvent during coating used for the image receiving two layers,
It is preferable to use a coating solvent that does not dissolve or swell the resin used for the image receiving layer. For example, when a vinyl chloride resin having relatively good solubility in various solvents is used as the material for the image receiving layer, it is preferable to use an alcohol-based or water-based coating solvent.

The thickness of the two image receiving layers is 0.1 to 1
0 μm is preferable, and 0.5 to 5 μm is more preferable. If the thickness is too large, the unevenness of the surface of the permanent support is impaired, the gloss becomes too high, and the printed matter approximation tends to be reduced.

In order to efficiently cause delamination between the organic polymer substance of one image receiving layer and the organic polymer substance of the two image receiving layers in the image receiving sheet material at the time of transfer to the permanent support, it is necessary to use each interlayer. The balance of adhesion is important. In order to control the interlayer adhesion, in addition to selecting a coating solvent to prevent mixing during multilayer coating, selection of materials such as a combination of a hydrophilic polymer and a lipophilic polymer or a combination of a polar polymer and a non-polar polymer, silane coupling It is effective to add an adhesion improver such as an agent, various additives having a fluorine or silicone release cure, and a surfactant to the image receiving layer or the image receiving two layers.

In the present invention, an intermediate layer may be provided between the two image receiving layers and the one image receiving layer for the purpose of adjusting transferability and the like.

The addition amount of the plasticizer in the two image receiving layers is not particularly limited, and is the same as in the case of the single image receiving layer. The thickness of the two image receiving layers is preferably from 0.2 to 30 μm, more preferably from 0.5 to 10 μm.

--Other Layers-- The other layers are not particularly limited and can be appropriately selected depending on the purpose. The material of the other layers is not particularly limited, and can be appropriately selected from known materials according to the purpose.

(Image Forming Method) In the image forming method of the present invention, an image receiving layer is provided on a support from a thermal transfer ink ribbon having a thermal transfer ink layer containing a colorant and a binder on the support. The thermal transfer ink layer is thermally transferred onto the resulting image receiving sheet material. At that time, 30 ° C, 70% humidity, RH
In the above, the difference between the water content of the thermal transfer ink layer and the water content of the image receiving layer must be 1.5% or less;
More preferably, it is 0.5% or less. If the difference in the water content exceeds 1.5%, the absolute value of the difference between the temperature and humidity dependence of the primary color recording sensitivity and the temperature and humidity dependence of the secondary color recording sensitivity increases, and the color balance becomes poor. .

The image forming method of the present invention can be suitably carried out using the image receiving sheet material of the present invention and the thermal transfer ink ribbon of the present invention. Specifically, the present invention can be carried out by using the thermal transfer ink ribbon of the present invention and a thermal head printer or a laser beam. In the image forming method of the present invention, for example, first,
When using the thermal head printer, on the thermal transfer ink layer of the thermal transfer ink ribbon, the image receiving layer of the image receiving sheet material is superimposed, pressing the thermal head from the back of the thermal transfer ink ribbon, after printing, The support in the thermal transfer ink ribbon is peeled from the image receiving sheet material. Then, a transfer image based on area gradation is formed on the image receiving sheet material. At this time, the transfer image formed on the image receiving sheet material was separately prepared, overlaid on a white support serving as a printing paper, and then subjected to pressure and heat treatment in this state. An image in which a transfer image formed on the image receiving sheet material is retransferred can also be obtained.

In the image forming method, the difference between the water content of the thermal transfer ink layer and the water content of the image receiving layer is 1.5.
%, It can be carried out by using a known image forming method using a thermal transfer ink ribbon, a thermal head printer, or the like. In forming the image, a laminate may be used in which the image receiving layer of the image receiving sheet material and the thermal transfer ink layer of the thermal transfer ink ribbon are brought into close contact with each other using a laminator or the like.

When an image is formed using a laser beam, the image forming method can be implemented by irradiating a laser beam imagewise instead of a thermal head. Image formation using laser light is disclosed in, for example, JP-A-6-219052,
An image forming method using so-called "ablation" can be used. Specifically, the image forming method described in the above publication is directed to a thermal transfer ink ribbon having the photothermal conversion layer and the heat sensitive release layer provided between a support and a thermal transfer ink layer (image forming layer) (or the photothermal conversion ink ribbon). When the layer contains the heat-sensitive material, a thermal transfer ink ribbon provided with a light-to-heat conversion layer also having the function of the heat-sensitive release layer),
Using the image receiving sheet material laminated on the thermal transfer ink layer, irradiation with laser light causes ablation due to alteration or melting of the light-to-heat conversion layer due to temperature rise of the light-to-heat conversion layer, and the heat-sensitive separation Part of the layer is decomposed and vaporized, the bonding force between the thermal transfer ink layer and the light-to-heat conversion layer is weakened, and the phenomenon that the thermal transfer ink layer in that region is transferred to the image receiving sheet material is used.

In the image formation using the ablation method, the heat transfer ink layer is melted by heat generated by the absorption of the laser beam, and the area is melt-transferred to the image receiving sheet material, thereby forming the image receiving sheet. A transfer image is formed on the material.

[0071]

EXAMPLES Examples of the present invention will be described below, but the present invention is not limited to these examples. Example 1 Production of Image Receiving Sheet Material A coating solution for an image receiving layer and a coating solution for an image receiving two layers having the following composition were prepared. -Coating solution for one image receiving layer- Binder: vinyl chloride-vinyl acetate copolymer ... 25 parts by weight (manufactured by Nissin Chemical Co., Ltd., MPR-TSL) Plasticizer: dibutyl octyl phthalate ... 12 parts by weight Part (DOP, manufactured by Daihachi Chemical Co., Ltd.) Surfactant: 4 parts by weight (MegaFac F-, manufactured by Dainippon Ink and Chemicals, Inc.) 177) Solvent: methyl ethyl ketone 75 parts by weight

-Coating solution for image receiving two layers- Binder: The following resin 1 16 parts by weight Binder: The following resin 2 4 parts by weight Binder: polyethyleneimine resin 0.5 parts by weight (Nippon Shokubai Co., Ltd., polyethyleneimine SP-200) Surfactant ... 4 parts by weight (MegaFac F-177, manufactured by Dainippon Ink and Chemicals, Inc.) Solvent: n-propyl alcohol 200 parts by weight

-Preparation of Resin 1- Polyvinyl butyral (trade name "ESLEK B BX-
10 ", manufactured by Sekisui Chemical Co., Ltd.) (105.1 parts by weight) was dissolved in acetone (389.7 parts by weight). 24.8 parts by weight of butyl isocyanate (0.5 equivalent to hydroxyl group) was added thereto. Further, dibutyltin diacetate 0.03
The mixture was stirred at 30 ° C. for 10 hours.
This solution was poured into 5 liters of water for reprecipitation purification, and further washed with water and dried to obtain 120.6 parts by weight of a resin 1 in which hydroxyl groups in polyvinyl butyral were converted to urethane groups.

Preparation of Resin 2 170 parts by weight of propylene glycol monomethyl ether were heated and stirred at 80 ° C. in a nitrogen stream, and 0.07 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) was added. Stir for 30 minutes. Butyl acrylate 3
1.6 parts by weight, N, N-dimethylacrylamide
4 parts by weight and 0.07 parts by weight of 2,2′-azobis (2,4-dimethylvaleronitrile) were added dropwise over 30 minutes. Thirty minutes and one hour after the completion of the dropwise addition, 0.15 parts by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) was further added, and the mixture was further heated and stirred for 4 hours.
Was obtained as a 28% propylene glycol monomethyl ether solution. The weight average molecular weight of Resin 2 was 13,000 (in terms of polystyrene).

On a polyethylene terephthalate (PET) film support having a thickness of 100 μm, the coating solution for the image receiving layer was applied at 300 rpm by using a rotary coating machine (Wheeler).
m and dried in an oven at 100 ° C. for 2 minutes.
The thickness of the obtained image receiving layer was 20 μm. The two-layer coating solution for image receiving was applied on the one image receiving layer at 200 rpm by using a rotary coating machine (whiter) and dried in an oven at 100 ° C. for 2 minutes. The thickness of the obtained two image receiving layers is 2
μm. The water content of the two image receiving layers under high temperature and high humidity (30 ° C., 70% RH) was 2.0%.

--Production of Thermal Transfer Ink Ribbon-- Amorphous organic polymer dispersions A and B having the following compositions were prepared. -Amorphous organic polymer dispersion A-Polyvinyl butyral ... 12 parts by weight (Denka Butyral # 2000-L, manufactured by Denki Kagaku Kogyo KK) Acrylic resin ... 6 parts by weight (Dianal BR-100 manufactured by Mitsubishi Rayon Co., Ltd.) Cyan pigment 12 parts by weight (CI Pigment Blue 15: 4) Dispersing aid 0.8 parts by weight (Solsperse S-20000, manufactured by ICI Japan) Solvent : Methyl ethyl ketone 55 parts by weight Solvent: n-propyl alcohol 55 parts by weight

-Amorphous Organic Polymer Dispersion B- Polyvinyl Butyral 12 parts by weight (Denka Butyral # 2000-L, manufactured by Denki Kagaku Kogyo KK) Acrylic resin 6 parts by weight (Dianal BR-100 manufactured by Mitsubishi Rayon Co., Ltd.) Yellow pigment 12 Parts by weight (CI Pigment Yellow 14) Dispersing aid 0.8 parts by weight (manufactured by ICI Japan K.K., Solsperse S-20000) Solvent : Methyl ethyl ketone 55 parts by weight Solvent: n-propyl alcohol 55 parts by weight

N-hydroxyethyl-dispersion was added to 10 parts by weight of each of the amorphous organic polymer dispersions A and B.
0.08 parts by weight of 1,2-hydroxystearic acid amide (Ito Oil Co., Ltd., Ito Wax J420) and 0.01 parts by weight of a surfactant (Dainippon Ink and Chemicals, Inc., Megafac F177) Parts, 30 parts by weight of methyl ethyl ketone and 30 parts by weight of n-propyl alcohol were added to prepare coating liquids A and B for a thermal transfer ink layer. The coating liquids A and B for the thermal transfer ink layer were coated on a 5 μm-thick polyester film (manufactured by Teijin Limited), which had been subjected to a mold release treatment on the back surface thereof, using a spin coater (Whaler).
The coating liquid A for the thermal transfer ink layer is coated so that the thickness after drying is 0.36 μm, and the coating liquid B for the thermal transfer ink layer is 0.42 μm. Each ribbon was manufactured.

Further, the temperature of the heat transfer ink layer was 30 ° C. and the humidity was 70%.
The water content at RH was measured to be 2.1% for both the cyan and yellow thermal transfer ink ribbons.

<Formation of Color Image> First, a cyan thermal transfer ink ribbon and an image receiving sheet material were superimposed and printed by a thermal head recording apparatus (prototype experimental machine) by the sub-scanning division method. In this apparatus, a thermal head of 75 μm × 50 μm is minutely fed in the direction of 50 μm, and is turned on and off at a pitch of 3 μm, thereby performing printing in a method of performing multi-stage modulation of only area gradation. After printing, the cyan thermal transfer ink ribbon was peeled off, and a cyan image consisting only of area gradation was formed on the image receiving sheet material. Next, the yellow thermal transfer ink ribbon is overlaid on the image receiving sheet material on which the cyan image is formed, printed in the same position, and thereafter, the yellow thermal transfer ink ribbon is peeled off to form a yellow image on the image receiving sheet material. Formed.

As a result, a color image consisting only of the area gradation was formed on the image receiving sheet material. Next, the image receiving sheet material on which the color image is formed is overlapped with art paper,
After passing through a heat roller of 4 m / sec at a pressure of 4.5 Kg / cm at a temperature of 4.5 ° C., the polyester film of the image receiving sheet material was peeled off, and the image receiving two layers on which the ink images were formed were transferred onto art paper. To form a color image.

<Evaluation of Dependence of Recording Sensitivity on Temperature and Humidity> The obtained thermal transfer ink ribbon and image receiving sheet material were conditioned at low temperature and low humidity (20 ° C. and 20% RH) for 24 hours.
First, the dot area ratio of the primary colors of cyan and yellow is 50.
% Of the printing energy ( _ELC , _ELY ) was obtained (the halftone dot area ratio ( _D1LY ) of the primary yellow color at this time was 50%). The dot area ratio was calculated from the optical density using the Murray-Davis equation. Next, with reference to the printing energy (E _LC, E _LY), performs image printing yellow image on the cyan image are overlapped on the position, the calculated yellow secondary color halftone dot area rate of the (D _2LY). Then, the thermal transfer ink ribbon and the image receiving sheet material are heated and humidified (30 ° C.).
After adjusting the humidity for 24 hours at a humidity of 70% RH), the halftone dot area ratio (D _1HY ,
In this case, it becomes 50%), and the dot area ratio (D 2 _HY ) of the yellow secondary color was obtained.

Temperature and Humidity Dependence of Primary Color Recording Sensitivity (D _1HY −
D _1LY ) and the temperature and humidity dependence of the secondary color recording sensitivity (D _2HY −
D _2LY ) ((D _1HY −D _1LY ) − (D _2HY −D
_{Those having} an absolute value of _2LY )) within 5% were evaluated as good, and those having an absolute value of more than 5% were evaluated as poor. Table 1 shows the results of the above evaluation, the difference in water content, and the like.

(Example 2) In Example 1, an acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., Dianal BR-10) was used.
Except that the addition amount of 0) was changed to 3 parts by weight, a thermal transfer ink ribbon was produced in the same manner as in Example 1, and the dependence of the recording sensitivity on temperature and humidity was evaluated. The evaluation results are shown in Table 1.

(Example 3) In Example 1, an acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., Dianal BR-10) was used.
Except that the addition amount of 0) was changed to 2 parts by weight, a thermal transfer ink ribbon was produced in the same manner as in Example 1, and the dependence of the recording sensitivity on temperature and humidity was evaluated. The evaluation results are shown in Table 1.

Comparative Example 1 In Example 1, an acrylic resin (manufactured by Mitsubishi Rayon Co., Ltd., Dianal BR-10) was used.
A thermal transfer ink ribbon was produced in the same manner as in Example 1 except that 0) was not added, and the dependence of the recording sensitivity on temperature and humidity was evaluated. The evaluation results and the like are shown in Table 1.

Comparative Example 2 In Comparative Example 1, the amount of N-hydroxyethyl-1,2-hydroxystearic acid amide (Itowax J-420, manufactured by Ito Oil Co., Ltd.) was changed to 0.24 parts by weight. Other than the above, a thermal transfer ink ribbon was manufactured in the same manner as in Comparative Example 1, and the dependence of the recording sensitivity on temperature and humidity was evaluated. The evaluation results and the like are shown in Table 1.

[0088]

[Table 1]

[0089]

According to the present invention, the temperature and humidity dependence of the primary color recording sensitivity (difference between the primary color recording sensitivity under high temperature and high humidity and the primary color recording sensitivity under low temperature and low humidity) and the temperature of the secondary color recording sensitivity. The absolute value of the difference between the humidity dependence (the difference between the secondary color recording sensitivity under high temperature and high humidity and the secondary color recording sensitivity under low temperature and low humidity) is small (that is, the absolute value of the difference between the two is small); A thermal transfer ink ribbon, an image receiving sheet material, and an image forming method which are excellent in color balance and high in performance can be provided. According to the thermal transfer ink ribbon, the image receiving sheet material, and the image forming method of the present invention, even if a large environmental change occurs, the color tone of the entire image can be corrected only by correcting the step tone of only the primary color, and the color reproduction can be performed. It is possible to provide a good-quality image.

Claims (5)

[Claims] 1. A thermal transfer ink ribbon having a thermal transfer ink layer containing a colorant and a binder on a support,
What is claimed is: 1. A thermal transfer ink ribbon for use in forming an image in which said thermal transfer ink layer is thermally transferred onto an image receiving sheet material having an image receiving layer on a support. A thermal transfer ink ribbon, wherein the difference from the water content of the image receiving layer is 1.5% or less. 2. The method according to claim 1, wherein the thermal transfer ink layer contains 30 to 70 colorants.
2. The thermal transfer ink ribbon according to claim 1, wherein the binder comprises 30 to 70 wt% of a binder, and the binder is an amorphous thermosoftening resin having a softening point of 40 to 150 ° C. 3. 3. A thermal transfer ink ribbon having a thermal transfer ink layer containing a colorant and a binder on a support,
An image receiving sheet material used for image formation in which the thermal transfer ink layer is thermally transferred onto an image receiving sheet material having an image receiving layer on a support, wherein the water content of the thermal transfer ink layer at 30 ° C. and 70% RH is determined. The difference from the water content of the image receiving layer is 1.5
% Or less. 4. The image receiving layer has one image receiving layer in contact with the support and two image receiving layers formed on the image receiving layer, and the water content of the image receiving layer is the water content of the two image receiving layers. The image receiving sheet material according to claim 3. 5. A thermal transfer ink ribbon having a thermal transfer ink layer containing a colorant and a binder on a support,
An image forming method for thermally transferring the thermal transfer ink layer onto an image receiving sheet material having an image receiving layer on a support,
An image forming method, wherein the difference between the water content of the thermal transfer ink layer and the water content of the image receiving layer at 70 ° C. and 70% RH is 1.5% or less.