JP4937982B2 - Thermal transfer sheet - Google Patents

Description

  The present invention relates to a heat-sensitive transfer sheet, and more particularly to a heat-sensitive transfer sheet having a small elongation of the heat-sensitive transfer sheet during high-speed printing and few image defects in printing.

Conventionally, various thermal transfer recording methods are known. Among them, the dye diffusion transfer recording method is attracting attention as a process capable of producing a color hard copy closest to the image quality of a silver salt photograph. In addition, it has the advantages of being dry, being able to visualize directly from digital data, and being easy to make duplicates, compared to silver halide photography.
In this dye diffusion transfer recording system, a heat-sensitive transfer sheet (hereinafter also referred to as an ink sheet) containing a dye and a heat-sensitive transfer image-receiving sheet (hereinafter also referred to as an image-receiving sheet) are superposed, and then heat is generated by an electrical signal. The ink sheet is heated by a controlled thermal head or the like, and the dye in the ink sheet is transferred to the thermal transfer image-receiving sheet to record the image information. The three colors of cyan, magenta, and yellow are superimposed and recorded. Thus, a color image having a continuous change in color shading can be transferred and recorded.

  In recent years, in the field of dye diffusion transfer recording system, various printers capable of printing at a higher speed than before have been developed and spread to the market. High-speed printing is a performance required for reducing the waiting time when a user prints at a store.

For the purpose of preventing fusion between the thermal printer head and the thermal transfer sheet and imparting slipperiness, the thermal transfer sheet on the side in contact with the thermal printer head is provided with a heat resistant slipping layer. Fusing may cause running failure called sticking during printing, or the thermal transfer sheet may be cut, and the lack of slipperiness is caused by deformation of wrinkles due to expansion of the thermal transfer sheet during printing. May cause image unevenness (print wrinkles). Since the thermal printer head comes into contact with the heat resistant slipping layer at a higher temperature and higher speed by high speed printing, further improvement in the performance of the heat resistant slipping layer is required.
For example, Patent Document 1 discloses that sticking can be improved by adding a talc having a shot-type abrasion degree to the heat-resistant slipping layer, and Patent Document 2 discloses that the heat-resistant slipping layer has an X-ray diffraction intensity. It is disclosed that sticking and printing wrinkles can be improved by including talc with a specified impurity content.
JP-A-8-90942 JP-A-8-90945

In consideration of improving the performance of the heat-resistant slip layer during high-speed printing, the heat-resistant slip layer was considered to contain the predetermined talc. It was found that the thermal transfer sheet had a particularly large elongation at the fifth sheet, which was insufficient as an improvement means for printing wrinkles, and it was found that a dot-like or streak-like image defect was produced in a low density print.
In the case of receiving images from a plurality of general customers and printing a large number of images continuously, only the first five print wrinkles are generated, but in the case of self-service that general customers print at the store, Frequently, the printer prints again after waiting for more than 10 minutes. For this reason, in order to take advantage of the advantages of high-speed printing, it has been required to improve the elongation of the thermal transfer sheet even when the printer is restarted after standby. In addition, since the print density area that causes image defects corresponds to the density of female faces in snapshots and the like, and is the density area that is desired to have the least image defects, further improvement of the thermal transfer sheet is also required in this respect. It was done.

  Accordingly, it is an object of the present invention to provide a thermal transfer sheet that can give an image with less printing wrinkles and less image defects due to the small elongation of the thermal transfer sheet in high-speed self-service printing.

As a result of intensive studies, the present inventors have found that the above object of the present invention can be achieved by the following means.
(1) Thermal transfer having a dye layer containing a heat transferable pigment and resin on one surface of the substrate film and a heat-resistant slipping layer containing talc particles and resin as one kind of inorganic particles on the other surface Each talc particle in the heat-resistant slipping layer is obtained from an electron beam image obtained by irradiating the heat-sensitive transfer sheet with an electron beam accelerated to 20 kV by a scanning electron microscope from the heat-resistant slipping layer side. When the corresponding projection area is obtained, the standard deviation of the projection area of the projection area of 10 square μm or more, the average projection area of 80 square μm or less, and the projection area of 10 square μm or more is calculated. A thermal transfer sheet, wherein the coefficient of variation obtained by dividing by the average projected area is 0.80 or less.
(2) When the projected area is 10 square μm or more and the average projected area is 40 square μm or less, and the projected area is 10 square μm or more, the standard deviation of the projected area is divided by the average projected area. The thermal transfer sheet according to (1), wherein the obtained coefficient of variation is 0.60 or less.
(3) The number of projected areas of talc particles in the heat resistant slipping layer of 100 square μm or more is 1 or less per 200,000 square μm area of the heat resistant slipping layer (1) or ( The thermal transfer sheet according to 2).
(4) In the heat-resistant slip layer, the Mohs hardness is 3 to 6, the average sphere equivalent diameter of the particles is 0.3 to 5 μm, and the ratio of the maximum width of the particles to the average sphere equivalent diameter is 1. The thermal transfer sheet according to any one of (1) to (3), which contains at least one inorganic particle other than talc, which is 5 to 50.
(5) The thermal transfer sheet according to any one of (1) to (4), wherein the heat-resistant slipping layer further contains a compound represented by the following general formula (P).
General formula (P)
{(R ¹ O) (R ² O) P (═O) O} _m M
(Wherein R ¹ represents an aliphatic group which may have a substituent or an aryl group which may have a substituent, and R ² represents a hydrogen atom, a metal ion, an aliphatic group which may have a substituent or An aryl group which may have a substituent, M represents a hydrogen atom, a metal ion or an ammonium ion, and m is the same as the valence of M and represents a number of 1 to 6.
(6) When the content of the talc particles and the content of the compound represented by the general formula (P) are 100 parts by mass of the compound represented by the general formula (P) The heat-sensitive transfer sheet according to (5), wherein the content of the talc particles is 30 parts by mass or more.
(7) The heat-sensitive transfer sheet according to any one of (1) to (6), wherein the heat-resistant slipping layer further contains a polyvalent metal salt of an alkyl carboxylic acid.
(8) The thermal transfer sheet according to any one of (1) to (7), wherein the substrate film has an easy-adhesion layer on at least one surface of the substrate film.
(9) The resin of the heat-resistant slipping layer has two or more hydroxyl groups in the polymer chain length end of the resin (that is, the end of the resin in the length direction of the polymer chain) or in the polymer structure. The thermal transfer sheet according to any one of (1) to (8).
(10) The thermal transfer sheet according to (9), wherein the resin is a polyacryl polyol resin.
(11) The thermal transfer sheet according to (9) or (10), wherein the resin of the heat-resistant slipping layer is crosslinked (preferably, crosslinked with a polyisocyanate-based crosslinking agent).
(12) The thermal transfer sheet according to (11), wherein the crosslinking reaction in the crosslinking is performed in a temperature range of 40 ° C. to 53 ° C. and in a period of 1 day to 20 days.
(13) The thermal transfer sheet is a thermal transfer sheet used in combination with a thermal transfer image-receiving sheet having a heat insulating layer containing a hollow polymer latex and a receiving layer containing a polymer latex on a support. The heat-sensitive transfer sheet according to any one of (1) to (12), which is characterized.
(14) A heat-sensitive transfer image-receiving sheet having a heat insulating layer containing a hollow polymer latex and a receiving layer containing a polymer latex on a support, and a dye containing a dye and a resin that can be thermally transferred to one surface of a substrate film A heat-sensitive transfer sheet having a heat-resistant slipping layer containing talc particles as one kind of inorganic particles and a resin on the other surface, a receiving layer of the heat-sensitive transfer image-receiving sheet, and a dye layer of the heat-sensitive transfer sheet And an image forming method for forming an image by applying thermal energy corresponding to an image signal from the heat-resistant slipping layer side of the thermal transfer sheet. An electron beam image obtained by irradiating the thermal transfer sheet with an electron beam accelerated to 20 kV by a scanning electron microscope from the side of the heat-resistant slipping layer is applied to each talc particle in the heat-resistant slipping layer. When the projected area is 10 square μm or more, the average projected area is 80 square μm or less, and the standard deviation of the projected area of the projected area is 10 square μm or more. A variation coefficient obtained by dividing by an average projected area is 0.80 or less.

  According to the present invention, it is possible to provide a thermal transfer sheet capable of giving an image with less printing wrinkles and less image defects due to the small elongation of the thermal transfer sheet during high-speed self-service printing.

Hereinafter, the present invention will be described in detail.
1) Thermal transfer sheet (Configuration of thermal transfer sheet (ink sheet))
The ink sheet is placed on the heat-sensitive transfer image-receiving sheet during thermal transfer image formation, and the dye (pigment) is transferred from the ink sheet to the heat-sensitive transfer image-receiving sheet by heating from the ink sheet side with a thermal printer head or the like. Used. The ink sheet of the present invention has a dye layer (thermal transfer layer) containing a thermally transferable dye and resin on one surface of a base film of the ink sheet, and a heat resistant slip property containing a lubricant and a resin on the other surface. Has a layer. An easy-adhesion layer (primer layer) can also be provided between the base film and the dye layer or between the base film and the heat-resistant slip layer.

(Heat resistant slipping layer)
In the present invention, the heat resistant slipping layer contains talc as inorganic particles.

(talc)
In the present invention, talc is a hydrous silicate mineral of magnesium, and the theoretical composition is Mg ₃ Si ₄ O ₁₀ (OH) ₂ . A three-layer structure in which a magnesium-containing layer is sandwiched between two layers of a silicate layer structure has a unit structure, and has a cleavage property because the bond between the silicate layers between the unit structures is weak. (Mohs hardness 1) and slipperiness. In addition, since it does not decompose to around 900 ° C. and is inert to most chemicals, it is a thermally and chemically stable substance. There are two types of talc, monoclinic and triclinic. In the present invention, any talc can be used, and a mixture of monoclinic and triclinic is also used. be able to.
The inclusion of talc in the heat-resistant slip layer makes it difficult to damage the thermal printer head due to the softness of talc. Therefore, it is useful in that the influence of fusion and corrosion on the thermal printer head is small. In the present invention, the talc contained in the heat resistant slipping layer is preferably 0.1% by weight or more, more preferably 0.2% by weight to 20% by weight, based on the total amount of the heat resistant slipping layer, 0.4 More preferably, 10% by mass to 10% by mass, and most preferably 0.8% by mass to 5% by mass.
In the present invention, the heat-resistant slipping layer can contain talc by coating the base film with a coating solution for the heat-resistant slipping layer in which raw material talc powder is previously dispersed. Usually, raw material talc is derived from natural minerals, but contains impurities due to natural products. In the present invention, talc refers to talc as a hydrous silicate mineral of magnesium without containing impurities in raw material talc. In addition, since the surface of the talc particles may contain various adsorbates or substituents such as hydroxyl groups unlike the inside of the talc particles, the elemental composition of talc may deviate somewhat from the theoretical composition. To do. Determination of whether or not talc is possible can be carried out by obtaining a diffraction peak by composition analysis and X-ray diffraction measurement and comparing the diffraction peak with a known talc diffraction peak.

Although the raw material talc is illustrated below, this invention is not limited to these examples.
As raw material talc, commercially available powdered talc derived from natural minerals can be used, for example, Micro Ace series, SG series, Nippon Talc Co., Ltd., high filler series, Matsumura Sangyo Co., Ltd., The PS series manufactured by Fukuoka Talc Kogyo Co., Ltd., the JET series manufactured by Asada Flour Milling Co., Ltd., the Hytron series manufactured by Takehara Chemical Industry Co., Ltd., or the MV series manufactured by Nippon Mytron Co., Ltd. (all trade names) I can list them. In the present invention, the average sphere equivalent particle size of talc contained in the raw material talc is preferably 0.5 to 10 μm, more preferably 0.8 to 5 μm, and most preferably 1 to 4 μm. The average sphere equivalent particle size of the raw material talc is a value obtained by a laser diffraction scattering method. Since the spatial distribution of the diffracted scattered light intensity obtained by irradiating light on the particles varies depending on the particle size, the particle size distribution is obtained by measuring and analyzing the spatial distribution of the diffracted scattered light intensity, and the average equivalent sphere diameter The particle size can be determined by calculation. This technique has been established as a laser analysis scattering method, and commercially available measuring instruments such as the SALD series manufactured by Shimadzu Corporation and the LA series manufactured by Horiba Ltd. (both trade names) can be used. .

The raw material talc is produced through steps such as beneficiation, pulverization, and classification of natural minerals. Raw material talc is a powder mainly composed of tabular grains. Since the ratio of the thickness of the flat plate shape to the area of the flat plate surface varies, the projected area of the flat plate surface of the talc particles in the heat-resistant slip layer cannot be defined by the average particle size of the raw material talc. In the present invention, it is defined using the projected area of talc in the heat resistant slipping layer, which will be described later.
In JP-A-8-90942, the use of raw material talc within a certain range of shot-type wear is used. The use of raw material talc having a diffraction peak intensity of impurities within a certain range is disclosed. Since the raw material talc is derived from natural products, there are various raw material talcs with different types and amounts of impurities. For this reason, there are various hardness and wear levels as raw material talc. In this invention, it is preferable that there are few impurities in raw material talc, and when using hard particles other than talc together with a heat resistant slipping layer, it is preferable to use together hard particles of high purity separately.
The impurities in the raw material talc are preferably few impurities that can form hard impurities. Specifically, Ca is preferably 0.5% by mass (hereinafter simply referred to as%) or less, preferably 0.1% or less. More preferably, Al is preferably 0.6% or less, more preferably 0.2% or less, and Fe is preferably 1.0% or less, more preferably 0.2% or less, and most preferably 0.05% or less. . Further, the moisture content is preferably small because it may affect the dispersibility when producing a dispersion for a heat resistant slipping layer, specifically 0.5% or less, preferably 0.2% or less. Is more preferable. When the impurities in the raw material talc are defined by the ratio (Y / X) of the maximum peak intensity (Y) derived from impurities to the maximum peak intensity (X) derived from talc in X-ray diffraction, this ratio is 0.40 or less. Is preferable, 0.20 or less is more preferable, and 0.10 or less is most preferable.

As the raw material talc has more hard impurities, the degree of wear increases. There are various methods for measuring the wear degree. For example, the shot-type wear degree can be measured as follows.
(Measuring method of shot-type wear)
1. Put 5g of raw material talc and 45ml of water into a 100ml glass container and stir.
2. Put 6 pre-weighed shots (lead diameter 4 mm) in the above container and cover.
3. The container containing the contents is stirred at 114 rpm for 5.5 hours using a stirrer (MixRotarVMR-5 (trade name) manufactured by AS ONE Corp.).
4). Remove the shot from the container after stirring, wash the shot well with water, remove the water attached to the shot, and measure the mass of the shot again.
5. A value (difference) obtained by subtracting the mass of the shot weighed after stirring is obtained from the mass of the shot weighed before stirring, and this is used as the shot-type wear degree.
The larger the shot-type wear level, the greater the amount of shot wear and the greater the wear.
The raw material talc preferably has few hard impurities. For this reason, the raw material talc preferably has a low degree of wear. For example, the shot-type wear degree is preferably 40 mg or less, more preferably 20 mg or less, and most preferably 10 mg or less.

Next, a method for producing a coating solution for the heat resistant slipping layer will be described.
Since the coating liquid for the heat-resistant slipping layer is a liquid containing solid particles that do not dissolve, such as talc particles, a method for producing a pigment dispersion used in the paint industry can be used.
In general, the production process can be roughly divided into a dissolution process and a dispersion process. The dissolution step is a step of dissolving a component that dissolves in the solvent for the coating solution in the heat resistant slipping layer component to form a solution, and generally involves dissolving the resin in an organic solvent. . A dispersion | distribution process is a process which mixes and disperse | distributes the said solution and solid powder components, such as raw material talc which is not melt | dissolved in the solvent for coating liquids in a heat-resistant slipping layer component. Since the solid powder component is generally a secondary agglomerated powder, the dispersion step includes (1) a step of wetting the powder surface with a solution, (2) loosening the agglomerated powder into primary particles, or A step of pulverizing, and (3) a step of stabilizing the dispersed particles. In the process (1), it is important that the powder surface is easily wetted by the solution, and the air on the surface of the powder and the solution are replaced. Therefore, the dispersion condition is high pressure or high shear force (shear stress). Is preferred. In the step (2), a high shearing force is indispensable as a dispersion condition in order to solve the powder aggregation. In the step (3), various additives are added in order to prevent re-aggregation even when the dispersed particles do not re-aggregate in the liquid, or when the coating liquid is dried after coating and the solvent disappears. be able to. Usually, the steps (1) to (3) proceed simultaneously in the same dispersion apparatus, but it is also preferable to provide a step (premixing) in which the step (1) is performed in advance. When the resin is cured with a crosslinking agent to form a heat resistant slipping layer, coating can be performed by further adding a crosslinking agent to the dispersed liquid containing the resin.

  A well-known thing can be used as a dispersion apparatus used for the said dispersion | distribution. For example, a three-roll mill disperses using a shearing force and pressing pressure acting on a contact point between rolls having different rotational speeds, and a sand mill and a bead mill stir media such as glass beads and zirconia beads in a container. It is dispersed using the impact force and shear stress obtained by this. The impact force and shear stress are limited because the media agitation in the bead mill is due to gravity, but it has been improved so that strong impact force and shear stress can be obtained by forcibly agitating the media with arms. There is an attritor. In addition to the above, for small-volume dispersion, in addition to the paint shaker that shakes and mixes small containers and the impact force and shear stress of the bead mill are limited, the container is forced to rotate and revolve simultaneously to force the media. There are planetary bead mills (or planetary ball mills) that have been improved so as to obtain a strong impact force and shear stress by stirring. For more detailed explanations, “Paint Flow and Pigment Dispersion”, published by Kyoritsu Publishing Co., Ltd., 1992, “Paints and Painting (Enhanced Edition)”, Power Corporation, 1994, “Emulsification / Dispersion Theory” And in theory, published by Tokushu Kagaku Kogyo Co., Ltd., 1997, and “Introduction to Printing Ink, Revised Edition”, published by the Japan Printing Society, Ltd., 2002.

  The heat resistant slipping layer is formed by coating the above-described coating solution by a known method such as gravure coating, roll coating, blade coating, or wire bar. The film thickness of the heat-resistant slipping layer is preferably 0.1 to 2.5 μm, more preferably 0.4 to 1.5 μm, and the coating amount is preferably 0.1 to 3.0 g per square meter, 0.5 to 2.0 g is more preferable.

As described above, it was found that the primary particles of raw material talc were pulverized in the dispersion process in order to impart a high shearing force. Since talc is soft, it has the usefulness that it is difficult to damage the thermal printer head, and at the same time, it is easily pulverized in the dispersion process. Grinding of raw material talc during the dispersion process occurs not only along the cleavage plane, but also in the direction of breaking both ends of the flat plate surface with the highest shear stress. Occasionally, it may aggregate again, and the shape of talc can be changed variously in the heat-resistant slip layer after coating.
As described above, the shape of the talc particles in the heat resistant slipping layer does not match the particle size and shape of the raw material talc. Furthermore, since the talc pulverization state varies greatly depending on the composition of the dispersion, the production scale, and the type of dispersion apparatus, the production conditions cannot be determined uniformly. For this reason, in the present invention, the distribution state of the projected area of the talc particles in the heat resistant slipping layer is defined by the following scanning electron microscope measurement.

Next, a method for measuring the projected area corresponding to the talc particles of the heat resistant slipping layer defined in the present invention will be described.
Measurement of an electron beam image (SEM image) using a scanning electron microscope (abbreviated as “SEM”) (preparation of measurement sample)
When the sample is charged by irradiating the electron beam, the electron beam fluctuates due to the electric field due to the charge, and the current value of the electron beam also fluctuates, so that accurate measurement cannot be performed. In order to prevent charging, the surface of the sample is covered with a conductive thin film to prevent charging. The conductive thin film is generally preferably formed by coating carbon (C) with a thickness of 20 nm to 35 nm by sputtering.

(Electron beam irradiation and SEM image measurement)
The electron beam to be irradiated preferably has an acceleration voltage of 20 kV and a beam diameter that converges as much as possible in order to ensure the resolution. In the surface observation in the SEM, the acceleration voltage is usually about 2 kV, but in the present invention, the acceleration voltage is 20 kV. When the acceleration voltage is 2 kV, the contribution of secondary electrons emitted from the vicinity of the observation surface is dominant in the SEM image, and the contribution of reflected electrons gradually increases as the acceleration voltage increases. The secondary electrons have a feature that the surface irregularities can be easily observed, but have a drawback that it is difficult to distinguish between a contrast image due to talc in the heat-resistant slipping layer and a contrast image due to unevenness on the surface of the heat-resistant slipping layer. The reflected electrons are those in which incident electrons are reflected, and the intensity of reflected electrons increases as the atomic number increases. Since the talc constituent elements Si and Mg have a larger atomic number than the organic matter in the heat resistant slipping layer, the reflected electrons can obtain a clearer talc image than the secondary electrons. Therefore, in order to increase the contribution of the reflected electrons, the acceleration voltage is increased compared with the normal SEM measurement. However, as the acceleration voltage is increased, the penetration depth of the incident electron beam increases and the scattering of the reflected electrons also increases. 20 kV was selected as an accelerating voltage that is easy to observe.

  In general, since SEM measurement is performed with the observation surface tilted in one direction with respect to the incident electron beam, the obtained SEM image is not an observation image from directly above, but with respect to the angle (Θ) between the incident electron beam and the observation surface. Is reduced by the ratio of sin (Θ) in the tilted direction. That is, when the angle (Θ) is 90 ° perpendicular (not tilted), sin (Θ) is not reduced by 1.0, whereas the angle (Θ) is tilted by 30 °. In this case, sin (Θ) is 0.5, which is reduced by a factor of 0.5 in the tilting direction. Since the projected area of talc in the heat resistant slipping layer defined in the present invention is the projected area from directly above the surface of the heat resistant slipping layer, correction is necessary for the SEM image measured by tilting. When the angle (Θ) is 30 °, it can be corrected by multiplying the length in the tilt direction by 2.0 times the reciprocal of the reduction ratio of 0.5. In the case of other inclination angles, correction can be performed in the same manner. A projected area corresponding to each talc particle in the heat resistant slipping layer is obtained from the SEM image thus measured. In the present invention, when talc particles overlap or aggregate in the heat resistant slipping layer and are observed as one talc image, it is evaluated as one talc particle, and one corresponding projected area is obtained.

(Determination method when inorganic particles other than talc coexist)
In the present invention, when inorganic particles other than talc particles are contained in the heat-resistant slipping layer, talc particles and other particles are distinguished by the following method.
(Distinction by characteristic X-ray measurement)
This is determined by measuring characteristic X-rays with an apparatus (abbreviated as “SEM-EDX” or “SEM-EDS”) equipped with an energy dispersive X-ray spectrometer in a scanning electron microscope (SEM). By using this apparatus, characteristic X-ray measurement can be performed in the same field of view as the SEM image. Specifically, first, SEM measurement is performed to identify a candidate talc particle. Next, the entire same region is scanned and measured by an EDX (energy dispersive X-ray spectrometer), and mapping by characteristic X-rays is performed. Elemental mapping by EDX is a method in which characteristic X-rays are measured and mapped at each location in a short time while scanning with an electron beam as in SEM measurement. Moreover, the characteristic X-ray intensity ratio derived from each element can be determined by fixing the measurement location and measuring the characteristic X-ray intensity derived from each element at each point. Since this ratio correlates with the composition, it can be used for discrimination.
(Example 1. When talc and muscovite coexist) Succulent is a plate-like particle having a cleavage property and similar in shape to talc particle, but the composition is KAl ₂ [(AlSi ₃ ) O ₁₀ ]. is there. By the element mapping, Mg characteristic X-rays are detected in the talc portion, while K and Al characteristic X-rays are not detected, whereas Mg characteristic X-rays are not detected in the muscovite portion. Since the characteristic X-rays of K and Al are detected, it can be clearly distinguished.
(Example 2. Forsterite coexisting with talc and one type of olivine) Forsterite has a composition of Mg ₂ SiO ₄ and has similar constituent elements as talc, but the composition ratio of Mg and Si is different. In this case, the characteristic X-ray intensity of Mg and Si is calculated in advance by measuring the characteristic X-rays of Mg and Si at the point of the talc particles with a heat-resistant slipping layer containing known talc. It is possible to determine whether or not the sample is talc by performing the same measurement on the sample to be determined and comparing it with the Mg / Si intensity ratio of talc calculated in advance.

  For more detailed explanations, see, for example, “Dictionary for Instrumental Analysis (Japan) Analytical Chemistry Society of Japan” published by Asakura Shoten Co., Ltd., 2005, “Surface Analysis Technology Selection, Electronic Probes and Microanalyzers, Japanese Surface Science Association”, Maruzen Co., Ltd. Published in 1998, and “EPMA Electron probe microanalyzer”, published by Konouchi Goro, Technical Shoin, 2001.

(Projected area corresponding to each talc particle in the heat-resistant slip layer)
In the present invention, for the projected area corresponding to each talc particle in the heat-resistant slip layer obtained by the above method, the number and the projected area are determined for those having a size of 10 square μm or more. Usually, a projected area corresponding to the talc particles is obtained for a region (for example, 0.5 mm × 0.8 mm square) of a heat-resistant slipping layer having a thickness of 400,000 square μm, and usually 200 or more projected areas are obtained. Furthermore, the average projected area, standard deviation, and coefficient of variation are calculated. The calculation formula is as follows.
Formula (1) (Average projected area) = (Sum of projected areas) / (Total number)
Formula (2) (standard deviation) = {[(each projected area) − (average projected area)] sum of squares / (total number)} to the 0.5th power (3) (variation coefficient) = ( Standard deviation) / (average projected area)
In the present invention, the average projected area is 80 square μm or less, preferably 60 square μm or less, and most preferably 40 square μm or less. Since the average projected area is 10 square μm or more, the average projected area is always 10 square μm or more.
The smaller the value of the coefficient of variation, the more the distribution of the projected area corresponding to talc is aligned. In the present invention, the coefficient of variation is 0.80 or less, more preferably 0.60 or less.
In addition, the number of projections corresponding to talc of 100 square μm or more is preferably 3 or less per 200,000 square μm, and most preferably 1 or less. When the number of projections corresponding to talc is 100 square μm or more, in order to increase the accuracy of the number, a wider heat-resistant slipping layer region (for example, 1 million square μm 1.0 mm × 1.0 mm square) It is preferable to determine the number of
In the present invention, as described above, the expansion of the thermal transfer sheet at the start of printing can be suppressed only when the average projected area is 80 square μm or less and the coefficient of variation is 0.80 or less. The printing wrinkle can be improved, and an excellent effect can be achieved in that dot-like or streak-like image defects in a low density region can be suppressed.
FIG. 1 is an actual electron micrograph (SEM image) of a heat-resistant slipping layer obtained at an acceleration voltage of 20 kV using a high resolution field emission scanning electron microscope S-4700 (trade name) manufactured by Hitachi, Ltd. In the electron micrograph (SEM image), the inclination angle between the incident electron beam and the observation surface is measured as 30 ° in the vertical direction. FIG. 1 shows an area of 400 μm × 500 μm.
In the photograph of FIG. 1, it is confirmed that the portion displayed whiter than the surroundings is a portion derived from talc, and the portion displayed whiter than the surroundings is confirmed in advance from the SEM-EDX measurement.
Here, the electron micrograph (SEM image) in FIG. 1 shows the talc particles in the heat-resistant slip layer of the present invention. The projected area corresponding to each talc particle in the photograph is 10 square μm or more. There are about 100 of them, the average projected area of those having a projected area of 10 square μm or more is 25 square μm, the variation coefficient of the projected area of 10 square μm or more is 0.50, and 100 square μm It turns out that there is no thing of the above projection area.

  In the present invention, in addition to talc, other additives such as inorganic particles, lubricants, plasticizers, stabilizers, fillers and fillers can be used in combination with the heat-resistant slip layer.

Inorganic particles other than talc include fluorides such as calcium fluoride, barium fluoride, and graphite fluoride, sulfides such as molybdenum disulfide, tungsten disulfide, and iron sulfide, silica, colloidal silica, lead oxide, alumina, oxidation Oxides such as molybdenum, graphite, mica, boron nitride, magnesium oxide (magnesia), magnesium hydroxide (brucite), magnesium carbonate (magnesite), magnesium calcium carbonate (dolomite), clays (kaolin, acid clay, etc.) Inorganic particles such as magnesium oxide, magnesium hydroxide, magnesium carbonate, magnesium carbonate calcium and kaolin are preferable, magnesium oxide, magnesium carbonate and magnesium calcium carbonate are more preferable, and magnesium oxide is most preferable. . Inorganic particles other than talc contained in the heat-resistant slipping layer are preferably 0.01% by mass to 50% by mass, more preferably 0.05% by mass to 30% by mass with respect to the total amount of the heat-resistant slipping layer, and 0.1% The mass% to 20 mass% is most preferable.
The size of the inorganic particles other than talc (average sphere equivalent diameter) is preferably from 0.1 μm to 50 μm, more preferably from 0.5 μm to 10 μm, and the particle shape may be any of an indefinite shape, a spherical shape, a cubic shape, a needle shape, a flat shape, etc. Although it can be used even if it is in a shape, needle-shaped and flat-shaped ones are preferably used. Among these, inorganic particles other than talc having a Mohs hardness of 3 to 6, an average particle diameter of 0.3 to 5 μm, and an average ratio of the maximum width of the particles to the sphere equivalent diameter of 1.5 to 50 are used. It is a more preferable aspect to use together.

  Organic substances other than talc include organic resins such as fluororesins and silicone resins, silicone oils, higher fatty acid alcohols, organopolysiloxanes, organic carboxylic acids, phosphate esters having OH groups, alkylcarboxylic acid polyvalent metal salts (stearin Zinc oxide, lithium stearate, etc.), phosphate ester ammonium salt or metal salt (stearyl zinc phosphate, etc.), polyethylene wax, various waxes such as paraffin wax, anionic surfactant, cationic surfactant, amphoteric interface Surfactants such as activators, nonionic surfactants, and fluorosurfactants can be exemplified. Among these, a silicone resin, an organopolysiloxane, an OH group-containing phosphate ester, an alkylcarboxylic acid polyvalent metal salt, an ammonium phosphate ester salt or a metal salt, which are effective in suppressing sticking and improving slipperiness, can be preferably used in combination. . Of these, phosphate esters having an OH group, polyvalent metal salts of alkylcarboxylic acids, ammonium phosphates or metal salts of phosphate esters are preferred.

The phosphate ester, phosphate ester ammonium salt or metal salt having an OH group is preferably a compound represented by the following general formula (P).
General formula (P)
{(R ¹ O) (R ² O) P (═O) O} _m M
In the formula, R ¹ represents an aliphatic group which may have a substituent or an aryl group which may have a substituent, and R ² represents a hydrogen atom, a metal ion or an aliphatic group or substituent which may have a substituent. An aryl group which may have a group is represented. M represents a hydrogen atom, a metal ion, or an ammonium ion. m is the same number as the valence of M and represents a number of 1 to 6.

Examples of the substituent that may be substituted by the aliphatic group or aryl group include an aliphatic group (alkyl group, alkenyl group, alkynyl group, cycloalkyl group, cycloalkenyl group, cycloalkynyl group, etc.), aryl group ( Phenyl group, naphthyl group, etc.), heterocyclic group, halogen atom, hydroxyl group, alkoxy group, alkenoxy group, cycloalkoxy group, cycloalkenoxy group, aryloxy group, heterocyclic oxy group, mercapto group, alkylthio group, alkenyl Thio group, arylthio group, amino group, alkylamino group, arylamino group, heterocyclic amino group, acylamino group, sulfonamide group, imide group, cyano group, nitro group, carboxyl group, sulfo group, carbamoyl group, sulfamoyl group, etc. Is mentioned.
Examples of the aliphatic group in R ¹ and R ² include an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, and a cycloalkenyl group, and examples of the aryl group include a phenyl group and a naphthyl group. Moreover, these substituents may be further substituted with these substituents.

R ¹ is preferably an aliphatic group, more preferably an alkyl group or an alkenyl group, and R ² is preferably a hydrogen atom or an aliphatic group, preferably a hydrogen atom, an alkyl group or an alkenyl group. These aliphatic groups, alkyl groups, and alkenyl groups may have the above-described substituents.
When R ¹ or / and R ² is an aliphatic group, the following groups are preferred.

R ^{11 to} R ¹⁴ each independently represents a hydrogen atom or a substituent. Examples of the substituent include a substituent that the aliphatic group or aryl group of R ¹ and R ² in the general formula (P) may have. R ^{11 to} R ¹⁴ are preferably a hydrogen atom or an alkyl group, and particularly preferably a hydrogen atom. n represents the number of 0-20, and 1-8 are still more preferable. R ¹⁵ represents an aliphatic group or an aryl group.
The aliphatic group for R ¹⁵ is preferably an alkyl group or an alkenyl group, and the number of carbon atoms is preferably 6 to 20, and more preferably 12 to 18. R ¹⁵ may have a substituent, and examples of the substituent include a substituent that the aliphatic group or aryl group of R ¹ and R ² in the general formula (P) may have. However, an unsubstituted aliphatic group is preferred.
Examples of the aryl group for R ¹⁵ include a phenyl group and a naphthyl group. The aryl group may have a substituent, and examples thereof include an aliphatic group represented by R ¹ and R ² in the general formula (P) and a substituent that the aryl group may have. Among them, an alkyl group is preferable. . In this case, the alkyl group preferably has 6 to 20 carbon atoms, and more preferably 12 to 18 carbon atoms.
R ¹⁵ is preferably an aliphatic group, more preferably a stearyl group or an oleyl group.
A case where n is 0 is also preferable in the present invention.

  M represents a hydrogen atom, a metal ion, or an ammonium ion. The metal ion may be a monovalent metal ion or a polyvalent metal ion. As monovalent metal ions, alkali metal ions are preferable, lithium ions, sodium ions and potassium ions are more preferable, and sodium ions are most preferable. The polyvalent metal ion is any polyvalent metal ion other than alkali metal ions, such as magnesium ion, calcium ion, zinc ion, copper ion, lead ion, aluminum ion, iron ion, cobalt ion, chromium ion and manganese. Examples thereof include magnesium ion, calcium ion, zinc ion and aluminum ion, and zinc ion is most preferable.

The ammonium ion is preferably an ion represented by the following general formula.
⁺ N (R ^A1 ) (R ^A2 ) (R ^A3 ) (R ^A4 )
In the above, R ^{A1 to} R ^A4 each independently represent a hydrogen atom, an alkyl group that may have a substituent, or an aryl group that may have a substituent. Examples thereof include the substituents that the aliphatic group or aryl group of R ¹ and R ² in P) may have. Of these substituents, a hydroxyl group and a phenyl group are preferable. Further, any two to three groups of R ^{A1 to} R ^A4 are bonded to each other to form a ring (eg, pyrrolidine ring, piperidine ring, morpholine ring, piperazine ring, indoline ring, quinuclidine ring, pyridine ring). Also good.
R ^{A1 to} R ^A4 are preferably a hydrogen atom or an alkyl group which may have a substituent.
Examples of ammonium ions include NH ₄ ⁺ , NH (CH ₂ CH ₂ OH) ₃ ⁺ , NH ₃ (CH ₂ CH ₂ OH) ⁺ , morpholinium, N (CH ₂ CH ₂ OH) ₄ ⁺ , NH ₃ (C ₄ H ₉ ) ⁺ is preferable, and NH ₄ ⁺ , NH ₃ (CH ₂ CH ₂ OH) ⁺ , and morpholinium are more preferable.

R ¹ is preferably an alkyl group having 12 to 18 carbon atoms, and R ² is preferably a hydrogen atom, a metal ion or an alkyl group having 12 to 18 carbon atoms. Moreover, although the compound represented with general formula (P) may be used individually or may be used in mixture of multiple, it is a case where multiple are used together.

Of the compounds represented by the general formula (P), many of the compounds in which M is a hydrogen atom are commercially available. -2, NIKKOL DDP-4, NIKKOL DDP-6, NIKKOL DDP-8, NIKKOL DDP-10, Dai Surf Industrial's Plysurf AL, Plysurf A208F, Plysurf A208N, Plysurf A217E, Plysurf A219B Toho Chemical Industry Co., Ltd. Phosphanol RB410, Phosphanol RB710, Phosphanol GF199, Phosphanol LP700, Phosphanol LB400, Sakai Chemical Industry Co., Ltd. Phoslex A-8, Phoslex A-18, Phos lexA-18D (both are trade names).
In addition, dilauryl phosphate ester, dioleyl phosphate ester, distearyl phosphate ester, and di (polyoxyethylene dodecyl phenyl ether) phosphate are exemplified.

In addition, many compounds in which M in the general formula (P) is a metal ion are commercially available, for example, Prisurf M208B, Prisurf M208F of Daiichi Kogyo Seiyaku Co., Ltd. Phanol RD720, Phosphanol GF185, Phosphanol GF215, Phosphanol RS710M, Phosphanol SC6103, Sakai Chemical Industry Co., Ltd. LBT-1830, LBT-1830 purified product, LBT-2230, LBT-1813, LBT -1820 (all are trade names).
Other than this, zinc salt of dilauryl phosphate, zinc salt of dioleyl phosphate, zinc salt of distearyl phosphate, sodium di (polyoxyethylene nonyl ether) phosphate, di (polyoxyethylene dodecyl phenyl ether) phosphate , Sodium di (polyoxyethylene decylphenyl ether) phosphate, and the like.

The total coating amount of the compound represented by the general formula (P) of the present invention is preferably 1% or more and 25% or less, and preferably 2% or more and 15% or less of the total coating mass of the heat resistant slipping layer. Is more preferable. Of these, those that are solid at room temperature are preferred.
If the solubility in the heat resistant slipping layer coating solution is low or does not dissolve, it is preferable to preliminarily form a powder form in order to accelerate or stabilize the dispersion in the heat resistant slipping layer coating solution, The particle size is preferably 0.1 μm to 100 μm, more preferably 1 μm to 30 μm.

  In the present invention, the content of talc in the heat resistant slipping layer is preferably 30 parts by mass or more and 40 parts by mass or more when the total content of the compound represented by the general formula (P) is 100 parts by mass. More preferred is 50 parts by mass or more. The upper limit is preferably 1000 parts by mass or less, more preferably 500 parts by mass or less, and still more preferably 400 parts by mass or less.

In the alkylcarboxylic acid polyvalent metal salt, the alkylcarboxylic acid is preferably an alkylcarboxylic acid having 8 to 25 carbon atoms, more preferably 12 to 21 carbon atoms, still more preferably 14 to 20 carbon atoms, such as octanoic acid or laurin. Acid, myristic acid, palmitic acid, stearic acid, behenic acid and the like. Examples of the polyvalent metal include divalent or trivalent metals, and alkaline earth metals and transition metals. For example, calcium, Magnesium, barium, strontium, cadmium, aluminum, zinc, copper, iron and the like can be mentioned, among which zinc is preferable. Alkylcarboxylic acid polyvalent metal salts include zinc laurate, zinc myristate, zinc palmitate, zinc stearate, zinc behenate, calcium stearate, magnesium myristate, barium stearate, aluminum stearate, copper stearate, etc. Among these, zinc stearate is preferable. These are commercially available or can be easily synthesized from the corresponding carboxylic acid.
These alkylcarboxylic acid polyvalent metal salts are preferably used in an amount of 0.1 to 50 parts by mass, and 0.5 to 10 parts by mass with respect to 100 parts by mass of the resin (binder resin) of the heat-resistant slip layer. Is more preferable.

  The amount of organic substances other than these resins contained in the heat-resistant slip layer varies, but 0.001% by mass to 50% by mass is preferable with respect to the total amount of the heat-resistant slip layer, and 0.01% by mass to 20 mass% is more preferable.

Although the heat-resistant slipping layer contains a resin, a known resin having high heat resistance can be used. Examples include cellulose resins such as ethyl cellulose, hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and nitrocellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl acetoacetal Resin, vinyl chloride-vinyl acetate copolymer, vinyl resin such as polyvinylpyrrolidone, polymethyl methacrylate, polyethyl acrylate, polyacrylamide, acrylic resin such as acrylonitrile-styrene copolymer, polyamide resin, polyimide resin, Polyamideimide resin, polyvinyltoluene resin, coumarone indene resin, polyester resin, polyurethane resin, polyether resin, polybuta Ene resin, polycarbonate resin, chlorinated polyolefin resin, fluorine resin, epoxy resin, phenol resin, silicone resin, and a single or a mixture of natural or synthetic resins such as silicone-modified or fluorine-modified urethane.
In order to improve heat resistance, the resin can be crosslinked by irradiation with ultraviolet rays or electron beams. It is also possible to crosslink by heating using a crosslinking agent. At this time, a catalyst can also be added. Examples of the crosslinking agent include isocyanate (polyisocyanate, cyclic trimer of polyisocyanate, etc.), metal (titanium tetrabutyrate, zirconium tetrabutyrate, aluminum triisopropylate, etc.) and the like. Examples of the resin to be reacted with these crosslinking agents include polyvinyl acetal, polyvinyl butyral, polyester polyol, alkyd polyol, and a silicone compound containing an amino group in the side chain.

It is known that the reaction with the crosslinking agent is promoted by placing the heat-resistant slipping layer in a high temperature and high humidity environment after coating. In this regard, in the present invention, it is preferable to select a condition in which the phosphate ester represented by the general formula (P) contained in the heat resistant slipping layer or the salt localized structure of the phosphate ester is not destroyed. Moreover, the combination of the said resin and a crosslinking agent can be selected so that a crosslinking reaction can fully be accelerated | stimulated on the conditions in which the said phosphate ester or salt localization structure in the heat-resistant slipping layer of this invention is not destroyed. A combination of a resin and a cross-linking agent that can sufficiently promote the cross-linking reaction within one day under a low humidity condition at 60 ° C. is preferable.
Such a resin preferably has two or more hydroxyl groups in the polymer chain length terminal or polymer structure of the resin. Here, the term “having two or more hydroxyl groups in the polymer chain length terminal or polymer structure of the resin” means that two or more hydroxyl groups are present in the structure that is not the polymer chain length terminal or the polymer terminal of the resin. It means having. Examples of such a resin include polyacryl polyol, polyester polyol, polyether polyol and the like. In the present invention, the polyacryl polyol includes polymethacryl polyol. In the present invention, among these, polyacryl polyol is preferable.
As the resin having two or more hydroxyl groups in the polymer chain length terminal or polymer structure of the resin, commercially available resins can be used, for example, Takelac (registered trademark) series manufactured by Mitsui Chemicals Polyurethane Co., Ltd., Soken Chemical Thermolac series manufactured by Hitachi Chemical Co., Ltd. Hitachiroid series manufactured by Harima Chemical Co., Ltd. Hariakuron series manufactured by Dainippon Ink Co., Ltd. Product name), but is not limited thereto.

  The hydroxyl value of a resin having two or more hydroxyl groups in the polymer chain length terminal or polymer structure of the resin is preferably 5 to 300, and most preferably 15 to 100, based on the solid content of the resin. The hydroxyl value is the number of mg of potassium hydroxide equivalent to the hydroxyl group in 1 g of a sample specified in JIS K-1557-1. The acid value of such a resin is preferably 20 or less, most preferably 0 to 10 based on the solid content of the resin. The acid value is the number of mg of potassium hydroxide required to neutralize the free acid in 1 g of a sample specified by JIS K-1557-5.

When cross-linking using an isocyanate-based cross-linking agent, the progress of the cross-linking reaction can be detected by detecting residual isocyanate groups by IR spectrum measurement. The IR spectrum peak intensity derived from the residual isocyanate group after the crosslinking reaction is 20% or less with respect to the IR spectrum peak intensity derived from the residual isocyanate group in the slipping layer, preferably 10% or less, most preferably 5% or less.
In order to efficiently exhibit the effects of the present invention, the temperature for promoting the reaction between the resin and the crosslinking agent is preferably 65 ° C. or less, more preferably 55 ° C. or less, and 40 ° C. to 53 ° C. Most preferably it is. The time for promoting the reaction between the resin and the crosslinking agent is preferably 12 hours or more and 40 days or less, more preferably 18 hours or more and 30 days or less, and most preferably 1 day or more and 20 days or less.

(Base film)
The base film of the heat-sensitive transfer sheet of the present invention is not particularly limited, and any conventionally known film can be used as long as it has the required heat resistance and strength. Examples include thin papers such as glassine paper, condenser paper, puffin paper, polyesters having high heat resistance such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polyphenylene sulfide, polyether ketone, polyether sulfone, polypropylene, polycarbonate, Specific examples of preferred supports are cellulose acetate, polyethylene derivatives, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, polyimide, polymethylpentene, ionomer and other plastic stretched or unstretched films, and laminates of these materials As mentioned. Among these, the polyester film is particularly preferable, the stretched polyester film is more preferable, and the polyester film is particularly preferably manufactured by stretching after forming an easy adhesion layer on at least one surface of the base film.
The thickness of the base film is appropriately selected according to the material so that the strength, heat resistance, etc. are appropriate, but those of about 1 to 30 μm are preferably used. More preferably, it is about 1-20 micrometers, More preferably, about 3-10 micrometers is used.

(Easy adhesion treatment)
The substrate film may be subjected to easy adhesion treatment for the purpose of improving the wettability and adhesion of the coating solution. As an easy adhesion treatment method, known resins such as corona discharge treatment, flame treatment, ozone treatment, ultraviolet treatment, radiation treatment, roughening treatment, chemical treatment, vacuum plasma treatment, atmospheric pressure plasma treatment, primer treatment, grafting treatment, etc. Surface modification techniques can be exemplified.
Among these, an easily bonding layer can also be formed by application | coating on a base film, and it is preferable to form an easily bonding layer in this invention. Examples of the resin used for the easy adhesion layer include polyester resins, polyacrylate resins, polyvinyl acetate resins, vinyl resins such as polyvinyl chloride resins and polyvinyl alcohol resins, and polyvinyl resins such as polyvinyl acetoacetal and polyvinyl butyral. Examples include acetal resins, polyether resins, polyurethane resins, styrene acrylate resins, polyacrylamide resins, polyamide resins, polystyrene resins, polyethylene resins, polypropylene resins, and polyvinylpyrrolidone resins. .
The base film used for the support can be formed by subjecting an unstretched film to a coating treatment and then a stretching treatment when the film is melt-extruded.
In addition, two or more kinds of the above treatments can be used in combination.
Here, as described above, in the present invention, a stretched film is preferably formed after forming an easy-adhesion layer on at least one surface of the substrate film. In the heat-sensitive transfer sheet of the present invention, it is preferable to provide an easy adhesion layer (dye barrier layer) between the dye layer and the substrate film.

  A thermal transfer layer (hereinafter also referred to as a dye layer) containing a dye for transfer (preferably a sublimable dye) can be formed by applying a dye coating solution.

(Dye layer)
In the dye layer of the present invention, it is preferable that a dye layer of each color of yellow, magenta, and cyan and, if necessary, a black dye layer are repeatedly coated on the same base film in the order of a plane. As an example, a case where the dye layers of yellow, magenta, and cyan are coated in the surface direction in correspondence with the area of the recording surface of the thermal transfer image-receiving sheet in the major axis direction on the same base film. Can be mentioned. In addition to these three layers, it is also preferable that either a black dye layer or a transferable protective layer (this may be a transferable protective layer laminate described later) or both are separately applied. It is.
When taking such an aspect, it is also a preferable aspect to provide a mark on the thermal transfer sheet for the purpose of transmitting the starting point of each color to the printer. Thus, by repeating the coating sequentially in the surface order, it is possible to form an image by transferring a dye and to laminate a protective layer on the image with a single thermal transfer sheet.
However, the present invention is not limited to the method of providing the dye layer as described above. A sublimation type thermal transfer ink layer and a heat melting transfer ink layer can be provided side by side, and it is also possible to change such as providing a dye layer of a hue other than yellow, magenta, cyan and black. Moreover, the form may be long, a single-wafer thermal transfer sheet, or may be preferably used in an embodiment in which the thermal transfer sheets before use are stored in an overlapped state.

(Dye layer coating solution)
The dye layer coating solution contains at least a sublimable dye and a binder resin, and if necessary, contains organic fine powder or inorganic fine powder, waxes, silicone resin, fluorine-containing organic compound and the like. This is also a preferred embodiment of the present invention.

In the heat-sensitive transfer sheet of the present invention, each dye is preferably contained in the heat-sensitive transfer layer in an amount of 20 to 80% by mass, and more preferably 30 to 70% by mass.
The dye layer is applied by a general method such as roll coating, bar coating, gravure coating, or gravure reverse coating. The coating amount of the dye layer is preferably 0.1 to 2.0 g / m ² (in terms of solid content, hereinafter the coating amount in the present invention is a numerical value in terms of solid content unless otherwise specified). Is 0.2 to 1.2 g / m ² . The film thickness of the dye layer is preferably from 0.1 to 2.0 μm, more preferably from 0.2 to 1.2 μm.

  The heat-sensitive transfer layer may have a single-layer structure or a multi-layer structure. In the case of a multi-layer structure, the composition of each layer constituting the heat transfer layer may be the same or different.

(dye)
The dye used in the present invention is not particularly limited as long as it is diffused by heat, can be incorporated into a thermal transfer sheet, and can be transferred from the thermal transfer sheet to the image receiving sheet by heating. Conventionally, the dye is used as a thermal transfer sheet. Dyes that have been used or publicly known dyes can be used.
Preferred dyes include, for example, methine series such as diarylmethane series, triarylmethane series, thiazole series, and merocyanine, indoaniline, acetophenone azomethine, pyrazoloazomethine, imidazolazomethine, imidazoazomethine, and azomethine series represented by pyridone azomethine. Cyanomethylene, thiazine, azine, acridine, benzeneazo, pyridoneazo, thiophenazo, isothiazoleazo, pyrroleazo, pyralazo, imidazoleazo, thiadiazole, typified by xanthene, oxazine, dicyanostyrene, tricyanostyrene Azos such as azo, triazole azo, and dizazo, spiropyrans, indolinospiropyrans, fluorans, rhodamine lactams, naphthoquinones, anthrax Down system, quinophthalone, and the like.

  For example, Disperse Yellow 231, Disperse Yellow 201, Solvent Yellow 93 and the like as yellow dyes, Disperse Violet 26, Disperse Red 60, Solvent Red 19 and the like as magenta dyes, and further cyan. Examples of the dye include, but are not limited to, Solvent Blue 63, Solvent Blue 36, Disperse Blue 354, Disperse Blue 35, and the like. It is also possible to arbitrarily combine the dyes of the above-mentioned hues.

(Resin for dye layer)
In the heat-sensitive transfer sheet of the present invention, the dye is usually coated on the substrate film in a state of being dispersed in a polymer compound called a resin (also called a binder or a resin binder). In this invention, a well-known thing can be used as a resin binder contained in a dye layer. Examples include acrylic resins such as polyacrylonitrile, polyacrylic acid ester and polyacrylamide, polyvinyl acetal resins such as polyvinyl acetoacetal and polyvinyl butyral, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, ethyl hydroxyethyl cellulose, methyl cellulose Cellulose resin such as cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, cellulose nitrate, etc. Cellulosic resin such as nitrocellulose, ethyl hydroxyethyl cellulose and ethyl cellulose, polyurethane resin, polyamide resin, polyester resin, polycarbonate resin, phenoxy resin , Phenolic resin, epoxy resin, various elastomers, etc. The recited dye layer by at least one resin selected from the group consisting of the above is configured.
In addition to using these alone, they can be mixed or copolymerized, and can be crosslinked with various crosslinking agents.
In the present invention, cellulose resins and polyvinyl acetal resins are preferable, and polyvinyl acetal resins are more preferable. Among them, polyvinyl acetoacetal resin and polyvinyl butyral resin are preferably used in the present invention.
The ratio (mass ratio) of the content of the dye in the dye layer may be any ratio, but is preferably 0.1 to 5.0, more preferably 0.5 to 3.0, and 9-2.0 is more preferable.

(Transferable protective layer laminate)
In the present invention, it is also preferable to provide the heat-sensitive transfer sheet with the transferable protective layer laminate in the surface order. The transferable protective layer laminate is for forming a protective layer made of a transparent resin on the heat-transferred image by thermal transfer to cover and protect the image, and has durability such as scratch resistance, light resistance, and weather resistance. The purpose is to improve performance. This is effective when image durability such as light resistance, scratch resistance and chemical resistance is insufficient if the transferred dye is exposed to the surface of the image receiving sheet.
The transferable protective layer laminate can be formed on the base film in the order of the release layer, the protective layer, and the adhesive layer from the base film side. It is also possible to form the protective layer with a plurality of layers. When the protective layer has the functions of other layers, the release layer and the adhesive layer can be omitted. As the support, a support provided with an easy-adhesion layer can also be used.

(Transferable protective layer)
The resin forming the transferable protective layer of the present invention is preferably a resin excellent in scratch resistance, chemical resistance, transparency and hardness, such as polyester resin, acrylic resin, polystyrene resin, polyurethane resin, acrylic urethane resin, and these Silicone-modified resins, ultraviolet blocking resins, mixtures of these resins, ionizing radiation curable resins, ultraviolet curable resins, and the like can be used. Of these, polyester resins and acrylic resins are preferable.
It is also possible to crosslink with various crosslinking agents.

(Transferable protective layer resin)
The acrylic resin is a polymer composed of at least one monomer selected from conventionally known acrylate monomers and methacrylate monomers, and may be copolymerized with styrene, acrylonitrile or the like in addition to the acrylic monomer. As a preferred monomer, methyl methacrylate is charged and contained in an amount of 50% by mass or more.
The acrylic resin of the present invention preferably has a molecular weight of 20,000 or more and 100,000 or less.

  As the polyester resin of the present invention, conventionally known saturated polyester resins can be used. When the polyester resin is used, the glass transition temperature is preferably 50 to 120 ° C., the molecular weight is preferably in the range of 2,000 to 40,000, and further in the range of 4,000 to 20,000. Sometimes the foil breakability is improved, which is more preferable.

(UV absorber)
In the present invention, the protective layer and / or the adhesive layer preferably contains an ultraviolet absorber. As the ultraviolet absorber, conventionally known inorganic ultraviolet absorbers and organic ultraviolet absorbers can be used. Examples of organic UV absorbers include salicylate-based, benzophenone-based, benzotriazole-based, triazine-based, substituted acrylonitrile-based, hindered amine-based non-reactive UV absorbers, and non-reactive UV absorbers such as, for example, Introducing an addition polymerizable double bond such as vinyl group, acryloyl group or methacryloyl group, or alcoholic hydroxyl group, amino group, carboxyl group, epoxy group, isocyanate group, etc. A polymerized or grafted product can be used. In addition, a method is disclosed in which a UV absorber is dissolved in a resin monomer or oligomer and then the monomer or oligomer is polymerized (Japanese Patent Application Laid-Open No. 2006-21333), and thus obtained UV blocking resin is used. You can also In this case, the ultraviolet absorber may be non-reactive.
Among these ultraviolet absorbers, benzophenone, benzotriazole, and triazine are particularly preferable. These UV absorbers are preferably used in combination so as to cover the effective UV absorption wavelength range according to the characteristics of the dye used for image formation. In the case of non-reactive UV absorbers, UV absorbers are used. It is preferable to use a mixture of a plurality of different structures so that the agent does not precipitate.
Commercially available UV absorbers include Tinuvin-P (manufactured by Ciba Geigy), JF-77 (manufactured by Johoku Chemical), Sea Soap 701 (manufactured by Shiraishi Calcium), Sumisop 200 (manufactured by Sumitomo Chemical), and Biosoap 520 (manufactured by Kyodo Yakuhin). , ADK STAB LA-32 (manufactured by Asahi Denka) and the like (all are trade names).

(Formation of transferable protective layer)
Although the formation method of a protective layer is dependent on the kind of resin used, it can form by the method similar to the formation method of the said dye layer, and the thickness of 0.5-10 micrometers is preferable.

(Release layer)
When the transferable protective layer is difficult to peel from the base film during thermal transfer, a release layer can be formed between the base film and the protective layer. A release layer may be further formed between the transferable protective layer and the release layer. The release layer includes, for example, waxes, silicone wax, silicone resin, fluororesin, acrylic resin, polyvinyl alcohol resin, cellulose derivative resin, urethane resin, acetic acid vinyl resin, acrylic vinyl ether resin, maleic anhydride resin, and It can be formed by coating and drying a coating solution containing at least one copolymer of these resin groups by a conventionally known method such as gravure coating or gravure reverse coating. Among the above resins, as the acrylic resin, a simple substance such as acrylic acid or methacrylic acid, or a resin copolymerized with other monomers, or a cellulose derivative resin is preferable. Excellent in releasability.
It is also possible to crosslink with various crosslinking agents, and ionizing radiation curable resins and ultraviolet curable resins can also be used.

  The release layer can be appropriately selected from those that transfer to the transfer medium during thermal transfer, those that remain on the substrate film side, or those that coagulate and break down. However, the release layer is on the substrate film side by thermal transfer. It is excellent in terms of surface glossiness, transfer stability of the protective layer, etc., so that the interface between the release layer and the transferable protective layer becomes the surface of the protective layer after thermal transfer. This is a preferred embodiment. The release layer can be formed by a conventionally known coating method, and the thickness is preferably about 0.5 to 5 μm in a dry state.

(Adhesive layer)
As the uppermost layer of the transferable protective layer laminate, an adhesive layer can be provided on the outermost surface of the protective layer. As a result, the adhesion of the protective layer to the transfer target can be improved.

2) Thermal transfer image-receiving sheet Next, a thermal transfer image-receiving sheet (hereinafter also simply referred to as an image-receiving sheet) that can be used in combination with the thermal transfer sheet of the present invention to form a thermal transfer print will be described in detail.
The thermal transfer image-receiving sheet has at least one receiving layer containing a thermoplastic receiving polymer for receiving a dye on a support. The receiving layer can contain an ultraviolet absorber, a release agent, a lubricant, an antioxidant, an antiseptic, a surfactant, and other additives. Between the support and the receiving layer, for example, an intermediate layer such as a heat insulating layer (porous layer), a gloss control layer, a white background adjustment layer, a charge control layer, an adhesive layer, a primer layer, etc. may be formed. It is preferable to have at least one heat insulating layer between the support and the receiving layer.
The receptor layer and these intermediate layers are preferably formed by simultaneous multilayer coating, and a plurality of intermediate layers can be provided as necessary.
A curl adjustment layer, a writing layer, and a charge adjustment layer may be formed on the back side of the support. In order to apply each layer on the back surface of the support, general methods such as roll coating, bar coating, gravure coating, and gravure reverse coating can be used.
In the present invention, any heat-sensitive transfer image-receiving sheet can be combined. However, in order to effectively exhibit the effects of the present invention, a heat insulating layer containing a hollow polymer (particle) latex is formed on a support. It is preferably used in combination with a thermal transfer image-receiving sheet having a receiving layer containing a polymer (particle) latex.

  The heat-sensitive transfer image-receiving sheet preferably uses a polymer latex capable of being dye-dyed on the receiving layer. The polymer latex may be used alone or in combination with a plurality of polymer latexes.

The polymer latex is generally a thermoplastic resin dispersed as fine particles in a water-soluble dispersion medium. Examples of the thermoplastic resin used in the polymer latex of the present invention include polycarbonate, polyester, polyacrylate, vinyl chloride copolymer, polyurethane, styrene-acrylonitrile copolymer, polycaprolactone, and the like.
Of these, polycarbonate, polyester, and vinyl chloride copolymer are preferable, and polyester and vinyl chloride copolymer are particularly preferable.

  The polyester is obtained by condensation of a dicarboxylic acid derivative and a diol compound, may contain an aromatic ring or a saturated carbon ring, and may be a water-soluble group for imparting dispersibility.

Vinyl chloride copolymer includes vinyl chloride and vinyl acetate copolymer, vinyl chloride and acrylate copolymer, vinyl chloride and methacrylate copolymer, vinyl chloride, vinyl acetate and acrylate copolymer, vinyl chloride And a copolymer of acrylate and ethylene. Thus, the copolymer may be a binary copolymer or a ternary or higher copolymer, and the monomers may be distributed irregularly or may be block copolymerized.
An auxiliary monomer component such as a vinyl alcohol derivative, a maleic acid derivative, or a vinyl ether derivative may be added to the copolymer. In the copolymer, the vinyl chloride component is preferably contained in an amount of 50% by mass or more, and auxiliary monomer components such as maleic acid derivatives and vinyl ether derivatives are preferably 10% by mass or less.
The polymer latex may be used alone or as a mixture. The polymer latex may have a uniform structure or a core / shell type, and at this time, the glass transition temperatures of resins forming the core and the shell may be different.

  The glass transition temperature (Tg) of such a polymer latex is preferably 20 ° C. or higher and 90 ° C. or lower, more preferably 25 ° C. or higher and 80 ° C. or lower.

Examples of commercially available acrylate latex include Nipol LX814 (Tg25 ° C.), NipolLX857X2 (Tg 43 ° C.), etc. (all trade names) manufactured by Nippon Zeon Co., Ltd.
Examples of commercially available polyester latex include Toyobo Co., Ltd., Vironal MD-1100 (Tg 40 ° C.), Vironal MD-1400 (Tg 20 ° C.), Vironal MD-1480 (Tg 20 ° C.), MD-1985 (Tg 20 ° C.), and the like. (Both are product names).
Commercially available vinyl chloride copolymers include Nivin Chemical Industry Co., Ltd., Vinybran 276 (Tg 33 ° C.), Viny Blanc 609 (Tg 48 ° C.), Sumika Chemtex Co., Ltd. Sumilite 1320 (Tg 30 ° C.), Sumi Elite 1210 (Tg 20 ° C.) and the like (both are trade names).

  The amount of the polymer latex added is preferably 50 to 98% by mass, more preferably 70 to 95% by mass, based on the total polymer content in the receptor layer. The average particle size of the polymer latex is preferably 1 to 50000 nm, more preferably 5 to 1000 nm.

It is preferable to contain a hollow polymer in the heat insulation layer.
In the present invention, the hollow polymer is a polymer particle having voids inside the particle, preferably an aqueous dispersion. For example, 1) water or the like inside the partition formed by polystyrene, acrylic resin, styrene-acrylic resin or the like. Contains dispersion medium. After coating and drying, non-foamed hollow polymer particles in which water inside the particles evaporates outside the particles and the inside of the particles becomes hollow. 2) Low boiling liquids such as butane and pentane are polychlorinated. It is covered with a resin made of vinylidene, polyacrylonitrile, polyacrylic acid, polyacrylic acid ester, or a mixture or polymer thereof. After coating, the inside of the particles expands due to expansion of the low-boiling liquid by heating. A foamed microballoon that becomes hollow, and 3) a microballoon made by heating and foaming the above 2) in advance to form a hollow polymer. And the like.
Among these, the non-foamed hollow polymer particles of 1) above are preferable, and two or more kinds can be mixed and used as necessary. Specific examples include Ropeke HP-1055 manufactured by Rohm and Haas, SX866 (B) manufactured by JSR, Nipol MH5055 manufactured by Nippon Zeon (all are trade names), and the like.

The average particle diameter of these hollow polymers is preferably 0.1 to 5.0 μm, more preferably 0.2 to 3.0 μm, and particularly preferably 0.4 to 1.4 μm.
The hollow polymer preferably has a porosity of 20 to 70%, more preferably 30 to 60%.

  The size of the hollow polymer particles is calculated by measuring the equivalent-circle diameter of the outer diameter using a transmission electron microscope. The average particle diameter is obtained by observing at least 300 hollow polymer particles using a transmission electron microscope, calculating the circle equivalent diameter of the outer shape, and averaging. The void ratio of the hollow polymer is determined from the ratio of the volume of the void portion to the particle volume.

  As the polymer characteristics of the hollow polymer, the glass transition temperature (Tg) is preferably 70 ° C. or higher and 200 ° C. or lower, more preferably 90 ° C. or higher and 180 ° C. or lower. As the hollow polymer, hollow polymer latex is particularly preferable.

  A water-soluble polymer can be contained in the receiving layer and / or the heat insulating layer of the heat-sensitive transfer image-receiving sheet. Here, the water-soluble polymer has a solubility of 0.05 g or more with respect to 100 g of water at 20 ° C., more preferably 0.1 g or more, and still more preferably 0.5 g or more.

  Examples of water-soluble polymers that can be used for the thermal transfer image-receiving sheet include carrageenans, pectin, dextrin, gelatin, casein, carboxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, polyvinylpyrrolidone, polyvinylpyrrolidone copolymer, polyvinyl alcohol, polyethylene glycol, Examples thereof include polypropylene glycol and water-soluble polyester. Of these, gelatin and polyvinyl alcohol are preferred.

Gelatin having a molecular weight of 10,000 to 1,000,000 can be used, and gelatin may contain anions such as Cl ⁻ and SO ₄ ²⁻ , Fe ²⁺ , Ca ²⁺ , Mg ^It may contain cations such as ²⁺ , Sn ²⁺ and Zn ²⁺ . It is preferable to add gelatin dissolved in water.
Moreover, well-known crosslinking agents, such as an aldehyde type crosslinking agent, an N-methylol type crosslinking agent, a vinyl sulfone type crosslinking agent, a chlorotriazine type crosslinking agent, can be added to gelatin. Of these, vinyl sulfone type crosslinking agents and chlorotriazine type crosslinking agents are preferred. Specific examples include bisvinylsulfonylmethyl ether, N, N′-ethylene-bis (vinylsulfonylacetamide) ethane, and 4,6-dichloro. -2-Hydroxy-1,3,5-triazine or its sodium salt.

  As the polyvinyl alcohol, various polyvinyl alcohols such as a completely saponified product, a partially saponified product, and a modified polyvinyl alcohol can be used. As for these polyvinyl alcohols, those described in Koichi Nagano et al., “Poval” (published by Kobunshi Shuppankai) are used. Polyvinyl alcohol can be adjusted in viscosity or stabilized by a trace amount of solvent or inorganic salt added to the aqueous solution. Specifically, the polyvinyl alcohol described in pages 144 to 154 can be used. it can. As a typical example, it is possible to improve the coating surface quality by containing boric acid, which is preferable. The addition amount of boric acid is preferably 0.01 to 40% by mass with respect to polyvinyl alcohol.

  Specific examples of polyvinyl alcohol include PVA-105, PVA-110, PVA-117, and PVA-117H as fully saponified products, and PVA-203, PVA-205, PVA-210, and PVA-220 as partially saponified products. Examples of the modified polyvinyl alcohol include C-118, HL-12E, KL-118, and MP-203. (All are trade names, manufactured by Kuraray Co., Ltd.)

  The receiving layer of the heat-sensitive transfer image-receiving sheet can contain a polymer compound having an aliphatic group substituted with a fluorine atom in the side chain. In this case, the thermal transfer sheet may contain the same polymer compound as the polymer compound having an aliphatic group substituted in the side chain with a fluorine atom substituted, or may contain a different polymer compound in the same category, This is a preferred embodiment. Moreover, you may contain solid waxes, such as well-known polyethylene wax and amide wax, silicone oil, a phosphoric ester compound, a fluorine-type surfactant, and a silicone-type surfactant as a mold release agent.

  The content of the polymer compound having an aliphatic group substituted with a fluorine atom in the side chain is 0.01% to 20%, preferably 0.1% to the total solid content (mass) of the receiving layer. 10%, more preferably 1% to 5%.

3) Image Forming Method Next, an image forming method that can be performed using the heat-sensitive transfer sheet of the present invention will be described.
In the image forming method, the thermal transfer image-receiving sheet is laminated so that the receiving layer of the thermal transfer image-receiving sheet and the thermal transfer layer such as the dye layer of the thermal transfer sheet are in contact with each other. An image is formed by applying from the layer side.
Specific image formation can be performed in the same manner as described in, for example, JP-A-2005-88545. In the present invention, the printing time is preferably less than 15 seconds, more preferably 3 to 12 seconds, and even more preferably 3 to 7 seconds from the viewpoint of shortening the time until the printed matter is provided to the consumer.

  In order to satisfy the above printing time, the line speed during printing is preferably 1.0 msec / line or less, more preferably 0.75 msec / line or less, and most preferably 0.65 msec / line or less. . Further, from the viewpoint of improving transfer efficiency in high-speed printing, the maximum temperature reached by the thermal head during printing is preferably 180 ° C. or higher and 450 ° C. or lower, more preferably 200 ° C. or higher and 450 ° C. or lower. Furthermore, 350 degreeC or more and 450 degrees C or less are preferable.

The heat-sensitive transfer sheet of the present invention can be used in printers, copying machines and the like using a heat-sensitive transfer recording system. As the means for applying thermal energy at the time of thermal transfer, any conventionally known means for applying may be used. By controlling the time, a print can be obtained by applying thermal energy of about 5 to 100 mJ / mm ² . The thermal transfer image-receiving sheet used in combination with the thermal transfer sheet of the present invention is a sheet- or roll-shaped thermal transfer image-receiving sheet capable of thermal transfer recording, cards, and transmission-type manuscript preparation by appropriately selecting a support. It can also be applied to various uses such as a sheet for use.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these. In Examples, “part” or “%” is based on mass unless otherwise specified.

Example 1
(Preparation of thermal transfer sheet)
The amount of the solid coating after drying is 1.1 g on the side opposite to the easy-adhesion layer of a 4.5 μm thick polyester film produced by stretching after an easy-adhesion layer is formed on one side as a base film. The heat-resistant slipping layer coating liquid A described later was applied so as to be / m ² . The ratio (—NCO / OH) of reactive groups between the polyisocyanate and the resin in the heat resistant slipping layer coating liquid A described later was 1.1. Immediately after the coating, it was dried in an oven at 100 ° C. for 1 minute and subsequently subjected to a heat treatment (60 ° C., 20 hours) to carry out a crosslinking reaction between the isocyanate and the polyol to be cured. After the heat treatment, unreacted isocyanate groups were confirmed by IR measurement to confirm that they were sufficiently reacted.
The yellow, magenta, and cyan dye layers and the transferable protective layer laminate are arranged in a plane order on the easy-adhesion layer-coated side of the heat-resistant slip layer-formed polyester film produced in this manner, using a coating liquid described later. A coated thermal transfer sheet was prepared. The solid content coating amount of each dye layer was 0.9 g / m ² . Immediately after these coatings, they were dried in a 100 ° C. oven for 1 minute.
The transferable protective layer laminate is formed by applying a release layer coating solution, coating the protective layer coating solution thereon, drying the coating layer, and further drying the adhesive layer coating solution thereon. Was applied.

Dispersion A for heat resistant slipping layer
Polyvinyl acetal resin 10.0 parts by mass (ESREC BX-1, trade name, manufactured by Sekisui Chemical Co., Ltd.)
Phosphoric acid ester having an OH group (compound represented by general formula (P)) 1.4 parts by mass (Foslex A-18, trade name, manufactured by Sakai Chemical Industry Co., Ltd .: 18 carbon atoms in the alcohol part)
Zinc stearate 0.2 parts by mass Raw material talc 1.2 parts by mass (average sphere equivalent diameter particle size 2.9 μm, maximum peak intensity (Y) derived from impurities relative to maximum peak intensity (X) derived from talc in X-ray diffraction) Ratio (Y / X) is 0.15, shot type wear degree is 25mg)
Methyl ethyl ketone / toluene mixed solvent 87.2 parts by mass

The resin and solvent of the dispersion liquid A for heat-resistant slipping layer were dissolved in advance, and other additives were added to the solution for premixing, followed by dispersion to prepare a dispersion. The dispersion condition was carried out under one of the following three conditions.
(Condition 1) Disperse for 120 minutes using a paint shaker (Condition 2) Disperse planetary ball mill P-7 (trade name) manufactured by Fritsch, Germany at 250 rpm for 40 minutes (Condition 3) Planetary ball mill manufactured by Fritsch, Germany Dispersed at 400 rpm for 40 minutes using P-7

Heat resistant slipping layer coating liquid Heat resistant slipping layer dispersion A 32.5 parts by weight Polyisocyanate (75% solution) 7.5 parts by weight (Bernock D-750, trade name, manufactured by Dainippon Ink & Chemicals, Inc.) )
Methyl ethyl ketone / toluene mixed solvent 70.0 parts by mass

Yellow Dye Layer Coating Liquid Dye Compound (Y-1) 2.0 parts by weight Dye Compound (Y-2) 5.1 parts by weight Dye Compound (Y-3) 0.8 parts by weight Polyvinyl acetal resin 6.9 parts by weight (Denka Butyral # 5000-D, trade name, manufactured by Denki Kagaku Kogyo Co., Ltd.)
Fluorine-containing polymer compound 0.1 part by mass (Megafac F-472SF, trade name, manufactured by Dainippon Ink & Chemicals, Inc.)
Matting agent (Flusen UF, trade name, manufactured by Sumitomo Seiko Co., Ltd.) 0.09 parts by mass Methyl ethyl ketone / toluene mixed solvent 85 parts by mass

Magenta dye layer coating solution Dye compound (M-1) 1.8 parts by weight Dye compound (M-2) 1.3 parts by weight Dye compound (M-3) 5.5 parts by weight Polyvinyl acetal resin 6.2 parts by weight (ESREC KS-1, trade name, manufactured by Sekisui Chemical Co., Ltd.)
Release agent 0.07 parts by mass (X-22-3000T, trade name, manufactured by Shin-Etsu Chemical Co., Ltd.)
Release agent 0.02 parts by mass (TSF4701, product name, manufactured by Momentive Performance Materials Japan GK)
Matting agent 0.11 parts by mass (Flusen UF, trade name, manufactured by Sumitomo Seiko Co., Ltd.)
85 parts by mass of methyl ethyl ketone / toluene mixed solvent

Cyan dye layer coating solution Dye compound (C-1) 1.4 parts by mass Dye compound (C-2) 7.6 parts by mass Dye compound (C-3) 0.8 parts by mass Polyvinyl acetal resin 5.0 parts by mass (ESREC KS-1, trade name, manufactured by Sekisui Chemical Co., Ltd.)
Fluorine-containing polymer compound 0.1 part by mass (Megafac F-472SF, trade name, manufactured by Dainippon Ink & Chemicals, Inc.)
Matting agent (Flusen UF, trade name, manufactured by Sumitomo Seiko Co., Ltd.) 0.1 part by mass Methyl ethyl ketone / toluene mixed solvent 85 parts by mass

(Transferable protective layer laminate)
A release layer, a protective layer and an adhesive layer coating solution having the following composition were applied to the same polyester film used for the preparation of the dye layer to form a transferable protective layer laminate. The coating amount of the releasing layer 0.2 g / ^{m 2} when dry film, the protective layer 0.4 g / ^{m 2,} and an adhesive layer 2.0 g / ^{m 2.}

Release layer coating solution Modified cellulose resin 5.0 parts by mass (L-30, trade name, Daicel Chemical)
Methyl ethyl ketone / toluene mixed solvent 95.0 parts by mass Protective layer coating solution Acrylic resin solution (solid content 40%) 90 parts by mass (UNO-1, trade name, manufactured by Gifu Ceramics Co., Ltd.)
Methanol / isopropanol mixed solvent 10 parts by mass Adhesive layer coating solution Acrylic resin 25 parts by mass (Dianaal BR-77, trade name, manufactured by Mitsubishi Rayon Co., Ltd.)
The following ultraviolet absorbent UV-1 0.5 part by mass The following ultraviolet absorbent UV-2 2 part by mass The following ultraviolet absorbent UV-3 0.5 part by mass The following ultraviolet absorbent UV-4 0.5 part by mass PMMA fine particles (poly Methyl methacrylate fine particles) 0.4 parts by mass Methyl ethyl ketone / toluene mixed solvent 70 parts by mass

(Preparation of thermal transfer image-receiving sheet)
The paper support surface laminated on both sides with polyethylene was subjected to corona discharge treatment, and then a gelatin subbing layer containing sodium dodecylbenzenesulfonate was provided. On this, an undercoat layer, a heat insulating layer, a receiving layer lower layer, and a receiving layer upper layer having the following composition are laminated in this order from the support side in FIG. 9 in US Pat. No. 2,761,791. The simultaneous multilayer coating was carried out by the method exemplified in 1. The coating amount at the time of drying is undercoat layer: 6.2 g / m ² , heat insulation layer: 8.0 g / m ² , receiving layer lower layer: 2.8 g / m ² , receiving layer upper layer: 2.3 g / m ² The coating was performed so that Moreover, the following composition represents the mass part as solid content.

Receiving layer upper layer 21.0 parts by mass of vinyl chloride latex (Viniblanc 900, trade name, manufactured by Nissin Chemical Industry Co., Ltd.)
1.6 parts by weight of vinyl chloride latex (Viniblanc 276, trade name, manufactured by Nissin Chemical Industry Co., Ltd.)
Gelatin (10% aqueous solution) 2.0 parts by mass The following ester wax EW-1 2.3 parts by mass The following surfactant F-1 0.09 parts by mass The following surfactant F-2 0.36 parts by mass Receiving layer lower layer 15.0 parts by weight of vinyl chloride latex (Viniblanc 690, trade name, manufactured by Nissin Chemical Industry Co., Ltd.)
11.0 parts by weight of vinyl chloride latex (Viniblanc 900, trade name, manufactured by Nissin Chemical Industry Co., Ltd.)
Gelatin (10% aqueous solution) 8.0 parts by mass The following surfactant F-1 0.04 parts by mass Thermal insulation layer Hollow polymer particle latex 66.0 parts by mass (MH5055, trade name, manufactured by Nippon Zeon Co., Ltd.)
Gelatin (10% aqueous solution) 24.0 parts by mass Undercoat layer Polyvinyl alcohol 7.0 parts by mass (Poval PVA205, trade name, manufactured by Kuraray Co., Ltd.)
Styrene butadiene rubber latex 55.0 parts by mass (SN-307, trade name, manufactured by Nippon A & L Co., Ltd.)
0.03 part by mass of the following surfactant F-1

  The thermal transfer sheet (101) is the sample to which the dispersion condition 1 is applied to the dispersion for the heat-resistant slipping layer, the thermal transfer sheet (102) is the sample to which the dispersion condition 2 is applied, and the thermal transfer sheet (102 is the sample to which the dispersion condition 3 is applied. 103). For the heat-sensitive transfer sheets (101) to (103), a phosphate ester having an OH group of the heat-resistant slipping layer is changed from Foslex A-18 (manufactured by Sakai Chemical Industry Co., Ltd.) alone to Foslex A-18 (Sakai Chemical). Kogyo Co., Ltd.) and Prisurf A208N (Daiichi Kogyo Seiyaku Co., Ltd .: mono- and di-polyoxyalkylene alkyl ether phosphate ester mixture) except that the mixture is changed to a 2 to 8 mixture (mass ratio). Thus, (106) was prepared from the thermal transfer sheet (104).

(Projected area of talc particles in the heat-resistant slip layer)
According to the method described in detail above, the heat-sensitive transfer sheet (101) was irradiated with an electron beam accelerated to 20 kV by a scanning electron microscope from the heat-resistant slip layer side, and an SEM image ( An electron beam image) is obtained, and a projected area corresponding to each talc particle in the heat-resistant slipping layer is obtained from this SEM image, and individual projections of the individual talc particles having a projected area of 10 square μm or more are obtained. The area was determined. From the individual projected areas thus obtained, the average projected area, the standard deviation and the variation coefficient (the projected area is 10), although the projected area is 10 square μm or more according to the above formulas (1) to (3). (The standard deviation of the projected area of a square μm or larger is divided by the average projected area). Values were similarly determined for the thermal transfer sheets (102) to (106). In each sample, the number of individual talc particles in the heat resistant slipping layer having a projected area of 10 square μm or more is about 50 to 200 per 200,000 square μm, and 200 to 400 individual talc particles in each sample. The projected area was determined.
Table 1 shows the composition of the heat-resistant slipping layer and the above values.

  From Table 1, it can be seen that even if the raw material talc is the same, the average value and the coefficient of variation of the projected area of the talc in the heat resistant slipping layer vary depending on the dispersion conditions. If it is effective to promote dispersion of talc, condition 3 with the strongest dispersion condition should have the smallest average value and coefficient of variation of the talc projection area, but this is not necessarily the case. It can be seen that it is not possible to achieve the prescribed range of the present invention by strengthening.

(Image formation, measurement and evaluation)
Using the thermal transfer sheet (101) and the image receiving sheet, five black solid images were continuously printed on a thermal transfer image receiving paper having a size of 152 mm × 102 mm by a thermal transfer printer having a resolution of 300 dpi. The line speed was 1.3 msec / line and 0.7 msec / line. The heat density of the thermal printer head was adjusted so that the print density of the black solid print was in the range of 2.15 to 2.25. The length of the thermal transfer sheet before and after printing was measured for the first and fifth sheets of five continuous prints, and the length before printing was calculated by subtracting the length before printing from the length after printing. Further, the elongation ratio was obtained by dividing the elongation length by the length of the printed portion. The larger the rate of elongation, the higher the frequency of occurrence of printing wrinkles, and the smaller the rate of elongation, the lower the frequency of occurrence of printing wrinkles.
A low density gray print was prepared in the same manner as described above except that the black solid print density 2.15 to 2.25 was changed to 0.19 to 0.21. Images of the produced gray prints were evaluated according to the following evaluation criteria.

(Grayprint image evaluation criteria)
A: No dot-like or streak-like defects are observed, and the print quality is very good.
B: Although there are slight dot-like or streak-like defects, the print quality is good.
C: Although there are dot-like or streak-like defects, the print quality is acceptable.
D: There are dot-like or streak-like defects, which are unacceptable as print quality.
E: There are a large number of dot-like or streak-like defects, which is not acceptable as print quality.

Printing was performed in the same manner except that the thermal transfer sheet (101) was changed to (102) to (106), and the evaluation was performed in the same manner. When black solid printing was continuously performed on a plurality of thermal transfer sheets, a printer standby time of 20 minutes or more was provided between the five continuous printings.
The results are shown in Table 2.

  From Table 1 and Table 2, it can be seen that the elongation of the thermal transfer sheet is particularly large in the first print in the high-speed printing (the time per line is short) in any sample. It can also be seen that the image quality tends to be worse when printing at higher speed. From these results, by setting the average value and the coefficient of variation of the projected area of the talc particles contained in the heat resistant slipping layer within the range specified in the present invention, the elongation of the thermal transfer sheet is suppressed in high-speed printing, In addition, it can be seen that the image quality can be improved, such as fewer image defects.

Example 2
Production of heat-sensitive transfer sheet (201) The composition of the heat-resistant slipping layer dispersion A and the composition of the heat-resistant slipping layer coating liquid are changed as follows with respect to the heat-sensitive transfer sheet (103) of Example 1. A thermal transfer sheet (201) was produced in the same manner except for the above.

Dispersion B for heat resistant slipping layer
16.7 parts by mass of polyacryl polyol resin (50% solution) (Acridic A-801-P, trade name, manufactured by Dainippon Ink & Chemicals, Inc., hydroxyl value with respect to resin solid content is 100 ± 6, acid value is 2-8)
Phosphoric acid ester having OH group 0.17 parts by mass (Fosrex A-18 manufactured by Sakai Chemical Industry Co., Ltd.)
Phosphoric acid ester having OH group 0.87 parts by mass (Pricesurf A208N manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
Zinc stearate 0.07 parts by mass Stearyl phosphate ester zinc salt 0.07 parts by mass Raw material talc (Microace L-1, trade name, manufactured by Nippon Talc Co., Ltd.) 0.62 parts by mass (average sphere equivalent particle size) 4.5 μm, ratio of maximum peak intensity (Y) derived from impurities to maximum peak intensity (X) derived from talc of X-ray diffraction (Y / X) is 0.39, shot-type wear degree 22 mg)
Methyl ethyl ketone / toluene mixed solvent 81.5 parts by mass

Heat resistant slipping layer coating solution Heat resistant slipping layer dispersion B 46.8 parts Polyisocyanate (75% solution) 2.3 parts by weight (Bernock D-750, trade name, manufactured by Dainippon Ink & Chemicals, Inc.) )
Methyl ethyl ketone / toluene mixed solvent 50.9 parts by mass

Preparation of thermal transfer sheets (202) to (209) Thermal transfer sheets (202) and (203) were similarly prepared except that the dispersion conditions of dispersion B for heat-resistant slipping layer were changed with respect to thermal transfer sheet (201). Was made. The thermal transfer sheets (204) to (208) were prepared in the same manner except that the raw material talc was changed to the following to change the dispersion conditions of the heat-resistant slip layer dispersion B for the thermal transfer sheet (201). did. In addition, the polyacrylic polyol resin of dispersion B for heat-resistant slipping layer was the same as polyvinyl acetal resin (ESREC BX-1, trade name, manufactured by Sekisui Chemical Co., Ltd.) as a solid content for heat-sensitive transfer sheet (206) The same except that the amount of polyisocyanate is changed so that the ratio (-NCO / OH) of the reactive group between the polyisocyanate and the resin in the heat resistant slipping layer coating solution is 1.1. Thus, a thermal transfer sheet (209) was produced.

Thermal transfer sheet (204)
The raw material talc is Microace P-3, trade name, manufactured by Nippon Talc Co., Ltd. (average sphere equivalent diameter particle size 4.9 μm, maximum peak intensity derived from talc in X-ray diffraction (X) The ratio (Y / X) of Y) was changed to 0.06 and the shot-type wear degree was 11 mg).

Thermal transfer sheet (205)
High filler # 5000PJ, trade name, manufactured by Matsumura Sangyo Co., Ltd. (average sphere equivalent diameter particle size 1.7 μm, maximum peak intensity derived from impurities (X) derived from talc in X-ray diffraction (Y) ) Ratio (Y / X) was changed to 0.07, shot-type abrasion degree 7 mg).

Thermal transfer sheet (206)
The raw material talc was made of high filler # 5000PJ, trade name, Matsumura Sangyo Co., Ltd. and all synthetic magnesium oxide (composition MgO, Mohs hardness 4, average sphere equivalent diameter particle size 1.2 μm, maximum particle width / The average equivalent sphere diameter was changed to a mixture of 85:15 at a mass ratio of 8.5). As a mixture, the ratio (Y / X) of the maximum peak intensity (Y) derived from magnesium oxide to the maximum peak intensity (X) derived from talc in X-ray diffraction was 0.23, and the shot-type abrasion degree was 23 mg.

Thermal transfer sheet (207)
The raw material talc was made of high filler # 5000PJ, trade name, Matsumura Sangyo Co., Ltd. and fully synthetic magnesium hydroxide (composition Mg (OH) ₂ , Mohs hardness 2.5, average spherical equivalent particle size 0.8 μm, The average particle maximum width / sphere equivalent diameter of each particle was changed to a mixture of 85:15 at a mass ratio of 12.5). The ratio (Y / X) of the maximum peak intensity (Y) derived from magnesium hydroxide to the maximum peak intensity (X) derived from talc in X-ray diffraction as a mixture was 0.21, and the shot-type abrasion degree was 8 mg.

Thermal transfer sheet (208)
The raw material talc, high filler # 5000PJ, tradename, Matsumura Sangyo Co., Ltd. and the total synthetic silica (composition SiO _2, Mohs hardness 7, the average sphere-equivalent diameter particle size 1.1 .mu.m, particle maximum width of each particle / The average sphere equivalent diameter was changed to a mixture of 85:15 at a mass ratio of 20.5). The ratio (Y / X) of the maximum peak intensity (Y) derived from silica to the maximum peak intensity (X) derived from X-ray diffraction talc as a mixture was 0.28, and the shot-type abrasion degree was 35 mg.

  The projected areas of the produced thermal transfer sheets (201) to (209) were determined for each talc particle in the heat-resistant slip layer in the same manner as in Example 1, and the average projected area and coefficient of variation were determined. Furthermore, the number of talc particles having a projected area of 100 square μm or more was determined, and the number of talc particles per 200,000 square μm area of the heat-resistant slip layer was calculated. The results are shown in Table 3.

  From Table 3, it can be seen that the average value and coefficient of variation of the projected area of the talc in the heat-resistant slipping layer can be within the scope of the present invention regardless of the amount of impurities and the degree of wear of the raw material talc and the inorganic particles used in addition to talc. .

(Image formation, measurement and evaluation)
The thermal transfer sheets (201) to (209) were used in the same manner as in Example 1 except that the line speed of the thermal transfer printer was changed from 1.3 msec / line to a line speed of 0.55 msec / line. Then, image formation, measurement and evaluation were performed.
The results are shown in Table 4 below.

  From Table 4, samples (201) to (209) in which various raw material talc and / or inorganic particles other than talc are used in combination are within the scope of the present invention, and at a printing speed of 0.7 ms / line, a thermal transfer sheet. Is small and is acceptable as an image quality. Furthermore, under the condition of 0.55 ms / line for high-speed printing, the samples (202) and (204) to (209) having a more preferable variation coefficient of 0.60 or less are particularly effective in suppressing the elongation of the first thermal transfer sheet. Is high. In addition, magnesium oxide is used as inorganic particles other than talc having a Mohs hardness of 3-6, an average particle size of 0.3 μm to 5 μm, and an average ratio of the maximum width of the particles to the sphere equivalent diameter of 1.5-50. It can be seen that the image quality of the sample (206) is further improved. It can also be seen that the sample (206) using polyacryl polyol is better in image evaluation than the sample (209) using polyvinyl acetal resin as the resin in the heat resistant slipping layer.

Example 3
Preparation of heat-sensitive transfer sheet (301) For heat-sensitive transfer sheet (206) of Example 2, heat treatment conditions (60 ° C., 20 hours) for crosslinking reaction of isocyanate and polyol are changed to 55 ° C. for 2.5 days. Similarly, except that the thermal transfer sheet (301) is changed to 50 ° C for 7 days, the thermal transfer sheet (302) is changed in the same manner except that the thermal transfer sheet (302) is changed to 42 ° C for 18 days. ) And 36 ° C. for 30 days to produce thermal transfer sheets (304) in the same manner. After the heat treatment, unreacted isocyanate groups were confirmed by IR measurement, and it was confirmed that the reaction was sufficiently performed under any heat treatment conditions.

  The projected areas of the produced thermal transfer sheets (301) to (304) were determined for the individual talc particles in the heat resistant slipping layer in the same manner as in Example 1, and the average projected area and variation coefficient were determined. Further, the number of projection areas of 100 square μm or more was determined, and the number of heat-resistant slip layers per 200,000 square μm area was counted. The results are shown in Table 5.

  From Table 5, samples (301) to (304) in which the heat treatment conditions for the crosslinking reaction at the time of forming the heat resistant slipping layer were changed have both the average value and the variation coefficient of the projected area of the talc particles in the heat resistant slipping layer. It can be seen that it is within the scope of the present invention.

(Image formation, measurement and evaluation)
Samples (301) to (304) were subjected to image formation, measurement and evaluation in the same manner as in Example 2.
The evaluation results are shown in Table 6 below.

  From Table 6, the samples (302) and (303), in which the heat treatment conditions in the samples (301) to (304) are in the range of 40 ° C. to 53 ° C. and 1 day to 20 days, It can be seen that the elongation of the thermal transfer sheet can be further reduced and the image quality can be improved.

It is an electron micrograph (SEM image) of the talc particle | grains in a heat resistant slipping layer.

Claims (14)

  A thermal transfer sheet having a dye layer containing a heat transferable pigment and resin on one surface of a base film and a heat-resistant slipping layer containing talc particles and a resin as one kind of inorganic particles on the other surface. Then, projection corresponding to each talc particle in the heat-resistant slipping layer from an electron beam image obtained by irradiating the heat-sensitive transfer sheet with an electron beam accelerated to 20 kV by a scanning electron microscope from the heat-resistant slipping layer side. When the area is obtained, the average projection area of the projection area of 10 square μm or more is 80 square μm or less, and the standard deviation of the projection area of the projection area of 10 square μm or more is the average projection. A thermal transfer sheet, wherein a coefficient of variation obtained by dividing by an area is 0.80 or less.   The variation obtained by dividing the standard deviation of the projected area by the average projected area of the projected area of 10 square μm or more and the average projected area of 40 square μm or less and the projected area of 10 square μm or more. The thermal transfer sheet according to claim 1, wherein the coefficient is 0.60 or less.   3. The number of projected areas of talc particles in the heat resistant slipping layer of 100 square μm or more is 1 or less per 200,000 square μm area of the heat resistant slipping layer according to claim 1 or 2. Thermal transfer sheet.   In the heat-resistant slip layer, the Mohs hardness is 3 to 6, the average sphere equivalent diameter of the particles is 0.3 to 5 μm, and the ratio of the maximum width of the particles to the average sphere equivalent diameter is 1.5 to 50 The thermal transfer sheet according to any one of claims 1 to 3, comprising at least one kind of inorganic particles other than talc. The thermal transfer sheet according to any one of claims 1 to 4, wherein the heat-resistant slipping layer further contains a compound represented by the following general formula (P).
General formula (P)
{(R ¹ O) (R ² O) P (═O) O} _m M
(Wherein R ¹ represents an aliphatic group which may have a substituent or an aryl group which may have a substituent, and R ² represents a hydrogen atom, a metal ion, an aliphatic group which may have a substituent or An aryl group which may have a substituent, M represents a hydrogen atom, a metal ion or an ammonium ion, and m is the same number as the valence of M and represents a number of 1 to 6.   When the content of the talc particles and the content of the compound represented by the general formula (P) are 100 parts by mass of the compound represented by the general formula (P), the talc The thermal transfer sheet according to claim 5, wherein the content of the particles is 30 parts by mass or more.   The heat-sensitive transfer sheet according to any one of claims 1 to 6, wherein the heat-resistant slipping layer further contains a polyvalent metal salt of an alkyl carboxylic acid.   The thermal transfer sheet according to any one of claims 1 to 7, wherein the base film has an easy-adhesion layer on at least one surface of the base film.   The heat-sensitive transfer sheet according to any one of claims 1 to 8, wherein the resin of the heat-resistant slipping layer has two or more hydroxyl groups in the polymer chain length terminal or polymer structure of the resin.   The thermal transfer sheet according to claim 9, wherein the resin is a polyacryl polyol resin.   The heat-sensitive transfer sheet according to claim 9 or 10, wherein the resin of the heat-resistant slipping layer is crosslinked.   The thermal transfer sheet according to claim 11, wherein the crosslinking reaction in the crosslinking is performed in a temperature range of 40 ° C. to 53 ° C. and in a period of 1 day to 20 days.   The thermal transfer sheet is a thermal transfer sheet used in combination with a thermal transfer image-receiving sheet having a heat insulating layer containing a hollow polymer latex and a receiving layer containing a polymer latex on a support. The heat-sensitive transfer sheet according to any one of claims 1 to 12.   On the support, a thermal transfer image-receiving sheet having a heat insulating layer containing a hollow polymer latex and a receiving layer containing a polymer latex, and a dye layer containing a dye and a resin capable of thermal transfer on one surface of the substrate film are provided. The heat-sensitive transfer sheet having a heat-resistant slipping layer containing talc particles as one kind of inorganic particles and a resin on the other surface is in contact with the receiving layer of the heat-sensitive transfer image-receiving sheet and the dye layer of the heat-sensitive transfer sheet. And forming an image by applying thermal energy corresponding to the image signal from the heat-resistant slipping layer side of the thermal transfer sheet, wherein the thermal transfer sheet is applied to the thermal transfer sheet. On the other hand, from the electron beam image obtained by irradiating the electron beam accelerated to 20 kV by the scanning electron microscope from the heat resistant slipping layer side, the projection corresponding to each talc particle in the heat resistant slipping layer is performed. When the area is obtained, the average projection area of the projection area of 10 square μm or more is 80 square μm or less, and the standard deviation of the projection area of the projection area of 10 square μm or more is the average projection. An image forming method, wherein a coefficient of variation obtained by dividing by an area is 0.80 or less.