JPH01127383A - 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 coloring transfer layer on a light absorbing base film. CONSTITUTION:An original negative film 3 is laid over the back surface of a photothermo-transfer sheet 10 of a corresponding color or an area of a corresponding color of a continuous sheet. This overlapped material is further laid over a material 4 to be subjected to transfer with an ink layer 2 opposed to the transfer material 4. In this condition, when light is directed through the original negative film 3, at the black part of the original negative film 3 the light fails to reach a light absorbing base film 1. On the other hand, at the transparent part thereof the light acts to the light absorbing base film 1 and heats the appropriate part, this heat reaches the ink layer 2 to soften the ink layer 2, the softened ink layer 2 is transferred on the transfer material 4, and a positive image 5 is formed thereon. By applying the aforesaid operation to the same transfer material 4 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 a base film, and images such as letters, graphics, or patterns are heated in the form of an image using a thermal head from the back side of the layer, and the colored transfer layer is thermally transferred to the surface of the transfer material. It is something to do.

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

The wax type uses a thermal transfer sheet that has 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, whereas the sublimation transfer type In this method, a dye that transfers when heated is supported on a base film using a suitable binder, and by heating from the back side, only the dye in the dye layer is thermally transferred to the surface of the transfer material to form an image. It is something.

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 the dots of each color is poor, and the 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) In order to meet the demands of the prior art as described above, the present inventors have proposed the following:
The present invention was completed as a result of 0 research.

That is, the present invention is a light-thermal transfer sheet characterized by having a colored transfer layer laminated on a light-absorbing base film.

(Function) Light with a colored transfer layer laminated on a light-absorbing base film.
By using a thermal transfer sheet, the light image formed by passing through the original negative film is converted into a thermal image by a light-absorbing base film, and this thermal image heats the colored transfer layer of the light-thermal transfer sheet to perform thermal transfer. , monocolor and multicolor images with excellent resolution and color reproducibility can be easily formed without using a thermal head.

(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 10 of the present invention may be the same as a conventionally known thermal transfer sheet, except that the base film 1 is light-absorbing as shown in FIG.

That is, conventional thermal transfer sheets include those having a heat-melting colored ink layer 2 on one side of a base film 1 that is softened by heat and peeled off to form an image (so-called wax type); It is known that the base film of these thermal transfer sheets has a dye layer 2 containing a so-called exogenous dye that sublimes by heat (so-called vengeance type) on one side. By doing so, the photo-thermal transfer sheet 1 of the present invention can be obtained.
Can be 0 and 1-.

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

As the base film l used in the present invention, the same base film used for conventional thermal transfer sheets can be used as is, except that it must be black or dark-colored and light-absorbing. Others can also be used and are not particularly limited.

As specific examples of preferable base film 1, 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,
Paper materials such as paraffin paper, non-woven 4F, etc. may be used, and a base film made of a combination of these materials may also be used.

The thickness of this base film l 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.

The method of making the base film 1 light-absorbing may be a known method. For example, when forming the film, a black pigment such as carbon black, a black dye such as nigrosine dye, etc. is added in an amount of 0.5 to 0.5 to 0. There are light-absorbing films on the market that are obtained by incorporating the film at a concentration of about 30%, or by dyeing it with black dyes such as disperse dyes after forming the film, and are colored black or dark. Any method that can be performed manually can be used in the present invention.

When the light-thermal transfer sheet 10 of the present invention is a wax type, the ink layer 2 consists of a colorant and a binder,
Furthermore, various additives may be added as necessary.

The colorant may be an organic or inorganic pigment or dye that has good properties as a recording material, such as one that has a color density of 1-minute and does not discolor due to light, heat, temperature, etc. preferable.

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 the binder, wax is used as a main component, and mixtures of wax and drying oil, resin, mineral oil, cellulose, rubber derivatives, etc. are used.

Representative examples of wax include microcrystalline wax, carnauba wax, paraffin wax, and the like. Furthermore, various waxes are used, such as Fischer-Tropsch wax, various low molecular weight polyethylenes, wood wax, beeswax, spermaceti wax, privet wax, wool wax, shellac wax, candelilla wax, petrolatum, assorted waxes, fatty acid esters, and fatty acid amides. It will be done.

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 2 on the light-absorbing base film 1 include hot melt coating, hot lacquer coating, gravure coating, gravure reverse coating, roll coating, and many other methods. Examples include a method of applying ink for forming an ink layer by means of a method.

The J5 thickness of the ink layer to be formed should be determined so as to balance the required density and thermal sensitivity, both of which should be 0.
．． It is in the range of 1 to 10 μm, preferably in the range of 1 to 5 μm.

When the light-thermal transfer sheet 10 of the present invention is of a sublimation transfer type, the dye layer 2 is a layer in which a dye is supported on the light-absorbing base film 1 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, as a red dye, MS Red G% Macrolex Red
Violet R1 (:eres Red 7B, S
amaron Red HBSL%S with Lupine 5EG1
．． Yellow dyes include Holon Brilliant Yellow S-6GL%PTY-52, Macrolex Yellow 5-6G, etc., and F1 color dyes include Kayacet Blue 14, Waxolinpur- AP-Fll, Holon Brilliant Blue-S-R, M
Examples include S Blue 100 and Daito Blue No. 1.

As a binder for supporting the above dyes,
Any conventionally known resin can be used, and preferred examples include cellulose resins such as ethyl cellulose, droxyethyl cellulose, ethyl hydroxy cellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and cellulose acetate; Vinyl resins such as alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinylpyrrolidone, and polyacrylamide, polyester, and the like are preferred from the viewpoint of heat resistance and heat transferability of dyes.

The dye layer 2 is basically formed from the above-mentioned materials, or may also contain various conventionally known additives as required.

Such a dye layer 2 is preferably prepared by adding the dye, binder resin, and other optional components to a suitable solvent and dissolving or dispersing each component to prepare a paint or ink for forming the dye layer. This is formed by coating and drying the above light-heat conversion layer 1.

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 5 to 90 μm of the weight of the dye layer.
Preferably, it is present in 1% by weight, preferably between 10 and 70.11 fEt%.

In the case of a wax type light-thermal transfer sheet, the transfer material used to form an image using a light-thermal transfer sheet such as the one described above may be paper, 71 paper, synthetic paper, mixed paper, etc. There are no particular limitations on the transfer material, such as general paper or plastic sheet, but in the case of a sublimation transfer type, it can be dyed with a dye, such as a plastic sheet with dye receptivity, paper with a dye receptive layer, etc. It is necessary that the material has a transfer surface that can be used.

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 are also included within the scope of the present invention.

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

The light-thermal transfer sheet 10 as described above is prepared in four colors by removing at least three colors, cyan, magenta, and yellow, and adding black if necessary. 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 coated on the same continuous base film in any desired manner, such as surface-sequentially or line-sequentially.

FIG. 2 is a diagram schematically showing a light-thermal transfer method using the light-thermal transfer sheet 10 (wax type) of the present invention.
As shown in the figure, cyan, magenta, and
Yellow and, if necessary, black original negative films 3 are prepared, and these original negative films 3 are placed on the back side of the light-thermal transfer sheet 10 of the corresponding color or the area of the corresponding color on the continuous sheet. This stacked layer is further stacked with the ink layer 2 facing the transfer material 4, and in this state light irradiation (ultraviolet light, visible light, infrared light, etc.) (arrow) is performed through the original negative film 3. does not reach the light absorbing film 1 in the black part (or light reflecting part) (non-image part) of the original negative film 3, and on the other hand, the transparent part (image part)
Then, the light-absorbing base film 1 is acted on to heat that part, and this heat reaches the ink layer 2 and softens the ink layer 2, and the softened ink layer 2 is transferred onto the transfer material 4 to form a positive image. Image 7 is formed.

By repeating the above operation once for each color on the same transfer material 4, a three-color or four-color image is formed as shown in the third figure, and one color image is created.

The original negative film 3 used in the above method may be any negative film, and it can be used as is, or it can be a normal original negative film for printing plates, or a film whose non-image area is coated with metal to make it light reflective is also available. Can be used.

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, the type of light-thermal transfer sheet, etc., or it is usually about 0.0001 to 10 seconds, preferably about 0.001 to 10 seconds, and one color is irradiated in a short time. It is 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 photo-thermal transfer should be carried out so that the original negative film, the photo-thermal transfer sheet and the transfer material are brought into close contact as much as possible so that the heat of the photo-thermal conversion layer is well transferred to the colored transfer layer. It is preferable that the sheet and the material to be transferred, preferably the three, be brought into sufficient contact with each other 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 2 is transferred to the transferred material to form an image. Same as above except that.

(Effects) According to the light-thermal transfer sheet of the present invention as described above, images with high resolution and excellent color reproducibility 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 Ink A having the above composition was applied to the negative side of a 3.5 μm thick black polyethylene terephthalate film (10% carbon black) so that the dry thickness was 5 μm (4+i).
and dried to obtain a photo-thermal transfer sheet of the present invention.

Ink A Carphone Black (Diablack G, manufactured by Mitsubishi Kasei)
3 parts ethylene/vinyl acetate combination (EV 8 Raflex 31O1 made by Mitsui Polychemicals) 1 part butterfin wax (paraffin 15 leaves, made by Honsei Wax) 10 parts Next, in place of carbon black as a pigment, yellow, magenta Yellow, magenta, and cyan photo-thermal transfer sheets of the present invention were prepared in the same manner as above using the pigments 1 and 2 and cyan, respectively.

Next, a full-color photographic original was subjected to halftone color separation for offset printing, and a negative film for four colors was used for α, and paper for binding was used as the transfer material.

First, the yellow original negative film 3, the yellow light-thermal transfer sheet 10, and the transferred material 4 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 A black aramid film (Ketchen Black 20%) with a thickness of 5 μm.Ink A with the following composition was applied to a thickness of 5 μm when dried! ? A photo-thermal transfer sheet of the present invention was prepared by fabricating and drying.

Ink A Carbon black (Diablack G, manufactured by 4 Kasei)
3 parts ethylene/vinyl acetate copolymer (manufactured by EV Hachiraflex 310 3-piece polychemical) IPlS butterfin wax (paraffin 15 leaves, ■made by Honki Wax) 1 part Next, replace carphone black as a pigment with yellow ,
Yellow, magenta and cyan photo-thermal transfer sheets of the present invention were prepared in the same manner as above using magenta and cyan pigments, respectively.

Next, a full color image was obtained in the same manner as in Example 1. This full-color image had excellent resolution and faithfully reproduced one original color.

Example 3 Three ink compositions for forming heat-transferable dye layers having the following compositions were prepared. These were coated on one surface of a 5 μm thick black polypropylene film (grossine dye 5%) at an i.k. of 1.0 g/ba and dried. A thermal transfer sheet of each color was obtained.

2.Kayaset Blue714 1
Part Foron Br1lliant BlueS-R5
1 part polyvinyl butyral resin 5 parts methyl ethyl ketone 45 parts toluene
45 Part 2 Hinokyūge MS Red G 3 Part Ma
crolex Red Violet R 2 parts Polyvinyl butyral resin 4 parts Methyl ethyl ketone 43 parts Toluene
43 part cyclohexanone
5th part Kogyokutan 2 舊Foron 1srillianL Yellow S
-8GL 5 parts polyvinyl butyral resin
5 parts methyl ethyl ketone
44 parts toluene 41 parts cyclohexanone 5 parts Next, synthetic paper (manufactured by Tamago Yuka Co., Ltd., Yupo FPG150) was used as a base sheet.
), and one of the coating liquids having the following composition was coated at a rate of 4.5 g/m'' when dried, and dried at 150.degree. C. for 30 minutes to obtain a transfer material.

Polyester resin (Vylon200, Oriental Union) 12
Vinyl chloride-vinyl acetate copolymer (VYII) l, u
cc) 5-part amino-modified silicone oil (NiF-:]9'l, Shin-Etsu Chemical Type) 1
Part epoxy-modified silicone oil (X-22-343, Shin-Etsu Chemical type) Part 1 Methyl ethyl ketone/toluene/cyclohexanone (weight ratio 4:4:2) Loo part Next, halftone dots for full-color photographic originals for offset printing The negative film of four colors formed by color separation was uploaded to Kawa, @shi.

First, the original negative film 3 for the yellow component, the yellow light-thermal transfer sheet 10, and the transfer material 4 are brought into sufficient vacuum contact, and the L'1M4 negative film side is flash-exposed with a xenon lamp to remove the yellow component from the transfer material. When it was peeled off, a yellow image 7 was formed.

Magenta 8, cyan 9, and black IO 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.

[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. 1: Base film 2: Colored transfer layer 3: Negative film 4: Transferred material 5: Yellow image 6; Magenta image 7: Cyan image 8 Black image 1O: Light-thermal transfer sheet Patent applicant Person Nippon Printing Co., Ltd. Agent Patent Attorney Yoshi 1) Katsuhiro.

Claims (3)

[Claims] (1) A light-thermal transfer sheet characterized by having a colored transfer layer laminated on a light-absorbing base film. (2) The light-thermal transfer sheet according to claim (1), wherein the colored transfer layer is a wax type. (3) The light-thermal transfer sheet according to claim (1), wherein the colored transfer layer is of a sublimation transfer type.