JPH01127381A - Photothermo-transfer sheet - Google Patents

Abstract

PURPOSE:To easily form a monochromatic color or multi-color image superior in resolving power and color reproducibility without using a thermal head, by laminating a photothermo-conversion layer, a base film, and a coloring transfer layer in this order. CONSTITUTION:A photothermo-conversion layer 1 is formed on the back surface of a base film 2. An original negative film 5 is laid over a photothermo-transfer sheet 100 of a corresponding color or an area of a corresponding color of a continuous sheet on the side the photothermo-conversion layer 1. This overlapped material is further laid over a material 6 to be subjected to transfer with an ink layer 3 opposed to the transfer material 6. In this condition, when light is directed through the original negative film 5, at the black part of the original negative film 5 the light fails to reach the photothermo-conversion layer 1. On the other hand, at the transparent part thereof the light acts to the photothermo-conversion layer 1 and heats the appropriate part, this heat reaches the ink layer 3 to soften the ink layer 3, the softened ink layer 3 is transferred on the transfer material 6, and a positive image 7 is formed thereon. By applying the aforesaid operation to the same transfer material 6 repeatedly once for every color, a three- or four-color image is formed and, thus, a color image is reproduced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a light-thermal transfer sheet, and more specifically to a light-thermal transfer sheet that can quickly produce beautiful, high-resolution images using a thermal transfer method without the need for mechanical heating means such as a thermal head. This invention relates to a novel light-thermal transfer sheet that can be provided to

(Prior Art) A thermal transfer method has been known as a simple printing method and image forming method. In this method, a colored transfer layer is formed on the base film L, and an image such as letters, graphics, or patterns is heated from the back side using a thermal head in the form of an image, and the colored transfer layer is applied to the surface of the material to be transferred. It is thermally transferred.

This thermal transfer method is roughly divided into two types, a wax type and a semitransfer type, depending on the structure of the colored transfer layer.

The wax type uses a thermal transfer sheet with a colored transfer layer formed on a base film that can be easily softened and transferred by heating, and transfers the colored wax layer to the transfer material. The Suno type uses an AM binder to support the dye, which sublimes or migrates when heated, on the base film, and then heats it from the back.
An image is formed by thermally transferring only the dye in the dye layer to the surface of the transfer material.

Both methods are capable of forming monochrome and multicolor images, and in the case of multicolor images, three or four color thermal transfer sheets are available, for example yellow, magenta, cyan, and black if necessary. Then, each color is aligned on the surface of the same transfer material and thermal transfer is performed to reproduce a color image.

In any case, a thermal head is used as the heating means.

(Problem to be solved by the invention) The thermal transfer method described above is developing as a simple image forming method to replace printing methods that have been used for a long time, such as offset printing and gravure printing, which are expensive and require large equipment. However, using a thermal head as a heating means has the following drawbacks.

(1) For example, since printing is performed line by line, it takes a relatively long time to complete an image.

(2) The size of the heating dot of the thermal head is approximately 50 mm.
The diameter is between 200 .mu.m and it is currently impossible to make it smaller than this, and therefore the dots forming the image are coarse, so the resolution of the image formed cannot be said to be sufficient.

(3) Especially when forming a three- or four-color image, in addition to the disadvantages of (1) and (2) above, it is necessary to return the transfer material to its original position three or four times. Therefore, the consistency of dots of each color is poor, and color reproducibility is insufficient.

Therefore, there is a demand for a thermal transfer sheet that can provide images with excellent resolution and reproducibility like conventional offset printing or gravure printing, without requiring mechanical heating means such as a thermal head, even though it is a thermal transfer method. has been done.

(Means for Solving the Problems) The present inventor completed the present invention as a result of intensive research in order to meet the demands of the prior art as described above.

That is, the present invention is a light-heat transfer sheet characterized in that a light-heat conversion layer, a base film, and a colored transfer layer are laminated in the order described above.

(Function) Using a light-thermal transfer sheet with a light-thermal conversion layer formed on the back surface, L? The light image formed by passing through the CM negative film is converted into a thermal image by a light-heat conversion layer, and the colored transfer layer of the light-thermal transfer sheet is heated by this thermal image to perform thermal transfer, using a thermal head. Therefore, monochrome and multicolor images with excellent resolution and color reproducibility can be easily formed.

(Preferred Embodiments) The present invention will now be described in more detail with reference to the accompanying drawings, which schematically show preferred embodiments of the invention.

The light-thermal transfer sheet 100 of the present invention may be the same as a conventionally known thermal transfer sheet except that it has a light-thermal conversion layer 1 as shown in FIG.

That is, conventional thermal transfer sheets include those having a heat-melting colored ink layer 3 on one side of a base film 2 that is softened by heat and peeled off to form an image (so-called wax type); A dye-supporting layer 3 containing a so-called sublimating dye that sublimes by heat on one side of the
(so-called Noboru type) are known, but by providing a light-to-heat conversion layer l on these thermal transfer sheets, the light-to-thermal transfer sheet 100 of the present invention can be obtained.
It can be done.

The light-heat conversion layer 1 is formed on the back side of the base film 2, preferably as a layer 1 containing a black or dark pigment or dye so that light can be efficiently absorbed and converted into heat. for example,
In order to convert the absorbed light into heat and efficiently reach the colored transfer layer 3, a resin or wax having a softening point or melting point of about 40 to 200°C is used as a binder, and a coloring agent such as carbon black is used. By applying ink or paint containing dispersed or dissolved
It is preferable to form the film with a thickness of approximately 100 m.

When such a light-heat conversion layer 1 is formed using a thermoplastic resin or wax having a relatively low softening point as a binder,
These layers 1 soften or melt during photo-thermal transfer.

As a result, it exhibits good thermal conductivity, and even if there are spaces between layer 1 and base film 2 that impede heat transfer, those spaces will disappear as layer 1 softens or melts, making it even more effective. It exhibits excellent thermal conductivity and can form excellent transferred images.

Furthermore, as will be described later, there may be cases where the layer 1 sticks to the original negative film 5 during light-thermal transfer, so a heat-resistant layer 4 made of a heat-resistant film or coating layer similar to the base film 2 is formed on its surface. is preferred.

This heat-resistant layer 4 is transparent so as to sufficiently transmit light from the light source, and is a thin layer, for example, 0.1 to 10#.
A thickness of about 1 m is preferable.

In order to prevent adhesion, for example, a fluorine-based slip agent, a fluororesin, or a surfactant such as a silicone-based surfactant may be added to the layer 1, the heat-resistant layer 4, or the coating layer. is also preferable.

Next, the present invention will be further explained by the materials used and the manufacturing method.

As the base film 2 used in the present invention, the same base film used in conventional thermal transfer sheets can be used as is, and other base films can also be used, and there are no particular limitations.

As specific examples of preferable base film 2, for example,
Plastics such as polyester, polypropylene, cellophane, polycarbonate, cellulose acetate, polyethylene, polyvinyl chloride, polystyrene, nylon, polyimide, polyvinylidene chloride, polyvinyl alcohol, fluororesin, chlorinated rubber, ionomer, condenser paper,
Papers such as paraffin paper, nonwoven fabrics, etc. may be used, and base films made of composites of these may also be used.

The thickness of the base film 2 can be changed as appropriate depending on the material so that its strength and thermal conductivity are appropriate, but the thickness is preferably, for example, 3 to 25 mm.
It is μm.

When the light-thermal transfer sheet 100 of the present invention is a wax type, the ink layer 3 is composed of a colorant and a binder, and may further contain additives such as a punch if necessary.

The coloring agent is preferably an organic or inorganic pigment or dye that has good properties as a recording material, for example, one that has sufficient color density and does not discolor or fade due to light, heat, temperature, etc.

Alternatively, it may be a substance that is colorless when not heated but develops color when heated, or a substance that develops color when it comes into contact with something coated on the transfer paper. In addition to the colorants forming cyan, magenta, yellow, and black, colorants of various other colors can also be used.

As a binder, wax is the main component, and mixtures of wax and drying oils, resins, mineral oils, cellulose, rubber derivatives, etc. are used. Typical examples of waxes include microcrystalline wax, carnauba wax,
There are paraffin waxes, etc. In addition, Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax,
Various waxes are used, such as beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolatum, partially modified wax, fatty acid ester, and fatty acid amino F.

Furthermore, a thermally conductive substance can be blended into the hot-melt ink layer in order to provide the hot-melt ink layer with good thermal conductivity and melt transferability. Examples of this substance include carbonaceous substances such as carbon black, aluminum, copper, tin oxide, and molybdenum dioxide.

Methods for directly or indirectly forming the heat-melting ink layer 3 on the base film 2 include hot melt coating, hot lacquer coating, gravure coating,
Examples include methods of applying the ink layer forming ink by gravure reverse coating, roll coating, and many other methods. The thickness of the ink layer formed should be determined so as to balance the required concentration and thermal sensitivity, both of which are in the range of 0.1 to 10 μm, preferably in the range of 1 to 5 μm.

When the photo-thermal transfer sheet 100 of the present invention is of a sublimation transfer type, the dye layer 3 is a layer in which a dye is supported on the base film 2 using an arbitrary binder resin.

The dye to be used is not particularly limited, and any dye used in conventionally known sublimation type thermal transfer sheets can be effectively used in the present invention.

For example, some preferred dyes include red dyes such as MS Red G, Macrolex Red
Violet R.

(:eres Red 7B, Samaron Re
Examples of yellow dyes include Holon Brilliant Yellow S-6GL, PTY-52, Macrolex Yellow 5-6G, etc., and examples of four-color dyes include d1-IBsL and SK Lupine 5EGL. , Kayaset Blue 14, Waxorin Blue AP-FJ
Holon Brilliant Blue S-R, MS Blue 100
, Tight Blue No. 1, etc.

As the binder for holding the above dyes, any conventionally known binder can be used, and preferred examples include ethyl cellulose, droxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, and methyl cellulose. , cellulose resins such as cellulose acetate and cellulose acetate butyrate, polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral,
Examples include vinyl resins such as polyvinyl acetal, polyvinylpyrrolidone, and polyacrylamide, with polyvinyl acetal, polyvinyl butyral, and the like being particularly preferred from the viewpoint of heat resistance and thermal transferability of dyes.

The dye layer 3 is basically formed from the above-mentioned materials, but may also contain various conventionally known additives as required.

Such a dye layer 3 is preferably prepared by adding the dye, binder resin, and other optional components in a suitable solvent, dissolving or dispersing each component, and preparing a paint or ink for forming a dye layer (14). It is formed by coating and drying on the above base film 2.

The dye layer formed in this way is 0.2 to 5.0 μm.
m, preferably about 0.4 to 2.0 μm, and the dye in the dye layer is present in an amount of 5 to 90% by weight, preferably 10 to 70% by weight of the weight of the dye layer. is preferable.

The light-to-heat conversion layer 1 provided on the back side of the base film 2 is a black or dark-colored layer, and has the function of absorbing light and converting it into heat. A method of applying a paint or ink containing a pigment to the back side of the base film 2, a method of laminating black or dark-colored films, etc. can be used. A coloring agent may be used, and the binder for the paint or ink may be the wax or resin used in the ink layer, the binder used in the dye-carrying layer, etc., and any conventionally known materials may be used without particular limitation.

In a preferred embodiment of the present invention, the light-to-heat conversion layer 1 is made of a thermoplastic resin having a relatively low softening point of about 50 to 100°C, the above-mentioned wax, or a 7B compound thereof as a binder to improve sensitivity. The light-to-heat conversion layer 1 can also have excellent thermal conductivity. In this case, as will be described later, when light is irradiated through the original negative film 5, the printing layer 1 easily softens or melts to form a thermal image, and the thermal image is quickly transmitted to the colored transfer layer 3, resulting in an excellent image. can be transcribed. However, in this case, since there is a possibility that the original negative film 5 may stick to the photo-thermal transfer sheet 100 of the present invention, it is preferable to form a heat-resistant layer 4 on the surface thereof. The heat-resistant layer 4 may be formed by laminating, for example, a film similar to Moeki Haas Film, or may be formed by coating a paint or ink containing a binder as described above, or may further include a light-to-heat converting layer on a transparent film. It is also possible to laminate a film formed on the back side of the base film. However, the heat-resistant layer 4 needs to be transparent.

In the case of a wax-type light-thermal transfer sheet, the transfer material used to form an image using the above-mentioned light-thermal transfer sheet may be paper, wood-free paper, synthetic paper, mixed paper, etc. There are no particular limitations on the material to be transferred, such as general paper or plastic sheets, but in the case of the Shoshin transfer type, it is possible to use dye-receiving materials such as plastic sheets that have poor dye receptivity, paper with a dye-receptive layer, etc. It is necessary that the material has a transfer surface that can be dyed.It goes without saying that the present invention can be applied to light-thermal transfer sheets for color printing, so multicolor light-thermal transfer sheets can also be used. within the scope of the invention.

Next, a method for forming a color image using the light-thermal transfer sheet of the present invention will be described.

A light-thermal transfer sheet 1 having a light-thermal conversion layer 1 as described above
As 00, at least three colors of cyan, magenta, and yellow are used, and black is added as necessary to prepare four colors. It goes without saying that these thermal transfer sheets may be sheet-fed as described above, or they may be continuous sheets in which each color is painted on the same continuous base film in a field-sequential or line-sequential manner.

FIG. 2 is a diagram schematically showing a light-thermal transfer method using the light-thermal transfer sheet 100 (wax type) of the present invention, and as shown in the figure, cyan, magenta, yellow, and If necessary, prepare a black original negative film 5, and apply these original negative films 5 to the light-thermal conversion layer 1 side of the corresponding color area on the light-thermal transfer sheet 100 of the corresponding color or the continuous sheet. Overlap. When this 1 [sticky material is further stacked with the ink layer 3 facing the transfer material 6 and in this state light irradiation (ultraviolet rays, visible light, infrared rays, etc.) (arrow) is performed through the original negative film 5, Light does not reach the light-to-heat conversion layer 1 in the black part (or light-reflecting part) (non-image part) of the original negative film 5, while it acts on the light-to-heat conversion layer 1 in the transparent part (image part). This heat reaches the ink layer 3 and softens the ink layer 3.
The softened ink layer 3 is transferred onto the transfer material 6 to form a positive image 7.

By repeating the above operation once for each color on the same transfer material 6, a three-color or four-color image is formed as shown in the third figure, and a color image is reproduced.

The original negative film 5 used in the above method may be any negative film, and in addition to ordinary original negative film for printing plates that can be used as is, it is also possible to use a film whose non-image areas are coated with metal to make it light reflective. Can be used by officials.

The light source used can be an ultraviolet light source, a visible light source, an infrared light source, or a mixture of these light sources, such as a general xenon flash lamp, incandescent lamp, or infrared lamp used in the plate-making process. , mercury lamps, lasers, etc. can be used as is. In addition, the light irradiation time cannot be defined unconditionally depending on the type of light source and the type of light-thermal transfer sheet, or it is usually about 0.000 to 100 seconds, preferably 0.001 to 10 seconds. Is it possible to complete the transcription? Note that the shorter the irradiation time, the more faithfully the original can be reproduced.

When carrying out the above method, at least the light-heat transfer layer should be used so that the original negative film, the light-thermal transfer sheet, and the transferred material are brought into close contact as much as possible so that the heat of the light-heat conversion layer is well transferred to the 7i color transfer layer. It is preferable that the thermal transfer sheet and the material to be transferred, preferably the three, are brought into intimate contact with each other for 1 minute using a vacuum.

The above example is an example using a wax type of the light-thermal transfer sheet of the present invention, and in the case of a sublimation transfer type, only the sublimation dye in the colored transfer layer 3 is transferred to the transferred material to form an image. Same as Section F except that.

(Effects) According to the light-thermal transfer sheet of the present invention as described above, images with high resolution and excellent color development can be easily and quickly formed without using a thermal head when forming images by a thermal transfer method. can.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

In the text, parts or percentages are based on weight unless otherwise specified.

Example 1 10 parts of carbon black, 20 parts of polyethylene wax, and 20 parts of acrylic binder were placed on the back side of a wax-type thermal transfer sheet (manufactured by Dai Nippon Printing Co., Ltd.) having successive sections of yellow, cyan, magenta, and black ink layers. The light-to-heat conversion layer 1 was formed by applying a black ink consisting of 50 parts of ink solvent (toluene + methyl ethyl ketone 1:1) to a thickness of about 3 μm (when dry) using a gravure coater and drying. Light-thermal transfer sheet 10
I got 0.

Next, a negative film for four colors formed by separating the halftone colors of a full-color photographic original for offset printing is injected, α,
Also, high-quality paper was used as the transfer material.

First, the yellow original negative film 5, the yellow light-thermal transfer sheet 100, and the transferred material 6 were brought into sufficient vacuum contact, and the original negative film side was exposed to flash light using a xenon lamp to peel off the transferred material. However, a yellow image 7 was formed.

Magenta 8, cyan 9 and black 10 were similarly transferred to the transfer material having yellow image 7 in the same manner as described above to obtain a full color image. This full-color image had excellent resolution and faithfully reproduced the colors of the original.

Example 2 20 parts of nigrosine dye was applied to the back side of a sublimation transfer type thermal transfer sheet (manufactured by Dainippon Printing Co., Ltd.) having continuous yellow, cyan, magenta, and black dye-supporting layers in one section each.
A black ink consisting of 10 parts of polyethylene wax, 20 parts of an ethylene-vinyl acetate copolymer binder, and 50 parts of an ink solvent (toluene + methyl ethyl ketone 1:1) was applied to a thickness of about 5 μm (when dry) using a gravure coater and dried. Forming a light-to-heat conversion layer, the light-to-heat conversion layer of the present invention is formed.
A thermal transfer sheet 100 was prepared. A full-color image was obtained in the same manner as in Example 1 using special paper (manufactured by Dainippon Printing Co., Ltd.) as the transfer material.

This full-color image had excellent resolution and faithfully reproduced the colors of the original.

Example 3 A transparent polyester film with a thickness of 3.5 μm was further laminated on the surface of the light-thermal conversion layer 1 formed in Example 1 to form a heat-resistant layer 4 to obtain the light-thermal transfer sheet 100 of the present invention, and the following implementation was carried out. A color image of excellent resolution was obtained in the same manner as in Example 1.

Example 4 A 20% solution of polyvinyl butyral was applied to the surface of the light-heat conversion layer 1 formed in Example 2 to a dry film thickness of 2 μm and dried to form a transparent heat-resistant layer 4. A color image with excellent resolution was obtained in the same manner as in Example 1 using the photo-thermal transfer sheet of the invention.

[Brief explanation of the drawing]

FIG. 1 is a diagram schematically showing a cross section of the light-thermal transfer sheet of the present invention, and FIG. 2 is a diagram schematically showing a method of forming an image using the light-thermal transfer sheet of the present invention. FIG. 3 is a diagram schematically showing a cross section of a color image formed by the method of FIG. 2. ! =Light-light-thermal-thermal conversion layer: Base film 3: Colored transfer layer 4: Heat-resistant layer 5: Negative film 6: Transferred material 7: Yellow image 8: Magenta image 9 Nidian image 10 Ni black image 100; 9 - Thermal transfer sheet patent application Person Dai Nippon Printing Co., Ltd. Attorney Yoshi 1) Katsuhiro

Claims (5)

[Claims] (1) A light-thermal transfer sheet characterized in that a light-thermal conversion layer, a base film, and a colored transfer layer are laminated in the stated order. (2) The light-thermal transfer sheet according to claim (1), wherein the light-thermal conversion layer is made of a material that softens or melts due to heat during light-thermal transfer. (3) The light-thermal transfer sheet according to claim (2), further comprising a heat-resistant layer formed on the surface of the light-thermal conversion layer. (4) The light-thermal transfer sheet according to claim (1), wherein the colored transfer layer is a wax type. (5) The light-thermal transfer sheet according to claim (1), wherein the colored transfer layer is of a sublimation transfer type.