JPH08187966A - Production of film which has image with high minuteness and is used for overhead projector - Google Patents

Abstract

PURPOSE: To make reproducibility of a dot good and to provide an image with high minuteness by using a thermal transfer recording medium on the surface of a porous layer side and thermally transferring an image and infiltrating heat meltable ink into fine pores of the porous layer in an arbitrary image shape and furthermore force-feeding a colorless transparent ink into the fine pores under heating and pressurization. CONSTITUTION: A heat meltable ink layer 3 of each color is provided on a base material 2. A transparent film 4 is superposed on a thermal transfer recording medium 1 and these are heated in such a state as these are pushed on a plate P by a thermal head T. A heat meltable ink of a heating part is melted. The heat meltable ink of the melting state is mainly infiltrated into fine pores 5 by capillary phenomena. When the transparent film 4 is separated from the thermal transfer recording medium 1, the transparent film is obtained in which the heat meltable ink is infiltrated into the fine pores 5 of the part corresponding to a heating element actuated by the thermal head T.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to thermal transfer recording on a transparency (transparent sheet) for an overhead projector (hereinafter sometimes referred to as OHP) (hereinafter sometimes referred to as a transparent film for OHP). OH having a high-definition image by transferring thermal transfer ink using a medium
The present invention relates to a method for producing a P film.

[0002]

2. Description of the Related Art Generally used transparent films for OHP have a smooth surface, and therefore, when a heat-meltable ink is transferred onto the surface of the transparent film by using a heat transfer recording medium, When forming a print of a desired size, transfer defects may occur when printing small or thin, and when printing large or thick, the transfer may be larger than the desired area. That is, there is a problem that a high-definition image cannot be obtained due to poor dot reproducibility.

In some cases, the adhesiveness between the transferred heat-meltable ink and the transparent film having a smooth surface may be poor. In such a case, if some external force is applied to the transferred heat-meltable ink, the heat-meltable ink is likely to fall off from the surface of the transparent film having a smooth surface. .

As a method for solving the above problems, there is a method for producing an OHP film having a high-definition image by dyeing an image on a transparent film by a sublimation type thermal transfer recording system. However, the sublimation type thermal transfer recording method has a disadvantage that the cost is higher than that of the thermal fusion type transfer recording method.

In addition, a dedicated O
There is a method of printing on a transparent film for HP. However, according to the inkjet method, the size of the dots printed cannot be made sufficiently small.
There is a problem that a high definition image cannot be obtained.

In order to solve these problems, JP-A-3-246095 discloses that a solution of plastic in a solvent is applied on a base material made of a transparent plastic film and then wet-solidified. A sheet provided with the porous plastic surface layer, which can be made transparent by printing with a hot-melt printer and then heating and / or pressure treatment, is described. However, by using the sheet provided with the porous plastic surface layer and performing the printing, heating and / or pressure treatment as described above, an image with good dot reproducibility can be obtained, but the white turbidity of the transparent plastic film When the temperature at the time of heating is raised so that a high-definition image cannot be obtained and whitening does not occur, the transferred image is It is disturbed and the definition is lost,
There is a problem that the transparent plastic film is thermally deformed.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points. That is, the object of the present invention is to adopt a heat-melting type transfer recording system, which has good dot reproducibility,
It is an object of the present invention to provide a method for inexpensively producing an OHP film having a high-definition image, in which the heat-meltable ink is hard to fall off from the transparent film surface.

[0008]

The present invention provides a method for producing an OHP film having an image by thermally transferring an image onto a transparent film by using a thermal transfer recording medium, wherein the image on the transparent film is thermally transferred. The surface of the porous layer is provided with a porous layer, and the image is thermally transferred onto the surface of the porous layer side by using a thermal transfer recording medium, so that the heat-meltable ink is applied to the micropores of the porous layer to form an arbitrary image. After intruding into a shape,
The present invention relates to a method (first invention) for producing a film for OHP having a high-definition image, characterized in that a colorless and transparent ink is further pressed into the fine holes under heat and pressure.

In the present invention, "colorless and transparent ink"
Is a colorless and transparent heat-melting ink, and in order to distinguish it from the heat-melting ink of a thermal transfer recording medium, the term heat-melting property is omitted and it is called a colorless and transparent ink.

In the first aspect of the present invention, the substrate having a colorless and transparent ink layer on one surface is made to face the colorless and transparent ink layer and the porous layer. The present invention relates to a method for producing an OHP film having a high-definition image (second invention), characterized in that the colorless and transparent ink is further pressed into the fine pores by superposing and heating.

Further, the present invention is based on the second invention.
OH having a high definition image, characterized in that a release layer is provided between the colorless and transparent ink layer and the substrate.
The present invention relates to a method for producing a film for P (third invention).

[0012]

According to the first aspect of the invention, an OHP having an image by thermally transferring an image onto a transparent film using a thermal transfer recording medium.
In the method for producing a film for use, a porous layer is provided on the surface of the transparent film on which the image is thermally transferred, and the image is thermally transferred using a thermal transfer recording medium on the surface of the porous layer side. By injecting the heat-meltable ink into the micropores of the porous layer in an arbitrary image shape, the colorless and transparent ink is further pressed into the micropores under heat and pressure to cause the heat-melting in the micropores. In the space that is not filled up with the transparent ink, the colorless and transparent ink is pressed into the deep part of the fine pores by the penetration pressure of the colorless and transparent ink, and the colorless and transparent ink is pressed into In the fine pores in which the transparent ink does not enter, the transparency of the film is improved by press-fitting the colorless and transparent ink to a deep portion, and an OHP film having a high-definition image can be obtained, According to an OHP film, it is possible to project an image of high definition screen.

According to a second aspect of the present invention, in the first aspect of the present invention, the colorless and transparent ink is press-fitted into a substrate having a colorless and transparent ink layer on one surface thereof. When the ink layer and the porous layer are overlapped with each other and heated and pressed so as to face each other, the base material serves as a cushion layer, and the transparent ink and the heat are applied as uniformly as possible to heat and pressure. In order to add to the fusible ink, the colorless and transparent ink is sufficiently pressed into the spaces or the fine pores into which the hot fusible ink has not entered, and when the substrate is peeled off, the colorless and transparent ink is easily Since the colorless transparent ink layer having a smooth surface is formed on the OHP film due to the peeling of the substrate, an OHP film having a higher definition image can be obtained.
With the HP film, it is possible to project a higher definition image on the screen.

According to the third invention, in the second invention, when the releasability between the substrate and the colorless and transparent ink is poor, the releasability between the substrate and the transparent ink layer is relieved. By providing the layer, the substrate can be easily peeled off from the colorless and transparent ink layer transferred to the OHP film side, and therefore the surface of the colorless and transparent ink layer is smooth, An OHP film having a high-definition image can be obtained, and the OHP film can project a high-definition image on a screen.

The method for producing an OHP film having a high definition image according to the present invention will be described in detail below with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a thermal transfer recording medium, in which a heat-meltable ink layer 3 of each color is provided on a substrate 2. In FIG. 2, 4 is a transparent film,
The surface has micropores 5 with a diameter and a depth of μm.
Are provided in large numbers. In the transparent film 4 shown in FIG. 2, the fine holes 5 are drawn regularly, but in reality, they are irregular.

As shown in FIG. 3, the thermal transfer recording medium 1 and the transparent film 4 are superposed and the thermal head T (see FIG.
(Only one heating element is shown in FIG. 2), the heat-melting ink in the heating portion is melted by heating while being pressed against the platen P. Break into 5. Then, when the thermal transfer recording medium 1 and the transparent film 4 are separated from each other, a transparent film in which the heat-melting ink has penetrated into the fine holes 5 in the portion corresponding to the operated heating element of the thermal head T is obtained.

Although FIG. 3 shows the transfer of a single color heat-meltable ink layer, in order to obtain a color by subtractive color mixing, for example, when red color is obtained, as shown in FIG.
First, the yellow heat-meltable ink 3Y is allowed to enter the fine holes 5, then the magenta heat-meltable ink 3M is allowed to enter, and both heat-meltable inks are superposed in the fine holes 5.
Similarly, a green color is obtained by combining the yellow heat-melting ink and the cyan heat-melting ink, and a blue color is obtained by combining the magenta heat-melting ink and the cyan heat-melting ink.
A black color is obtained by a combination of the yellow heat-meltable ink, the magenta heat-meltable ink, and the cyan heat-meltable ink.

The melt viscosity of the heat-meltable ink layer of each color in the present invention is preferably in the range of 20 to 1000 cps / 90 ° C., especially 50 to 500 cps / 90 ° C. By defining the melt viscosity of the heat-meltable ink layer in the above range, the heat-meltable ink can surely enter the fine pores of the transparent film. Further, the coating amount of the heat-meltable ink layer of each color is 0.5 to 4 g /
m ² , above all in the range of 0.5-2.5 g / m ² ,
The substrate has a thickness of 1 to 12 μm, especially 2 to 6 μm, and the total thickness of the thermal transfer recording medium is 2.5 to 16 μm.
m, above all, preferably in the range of 2.5 to 8 μm. By defining the coating amount of the heat-fusible ink layer of each color, the thickness of the substrate, and the thickness of the entire thermal transfer recording medium within the above range, it is possible to diffuse the heat energy from the heating element in the surface direction. As much as possible, the heat-meltable ink can be transferred in an area as close as possible to the area of the heating element.
Further, mainly by virtue of the viscosity regulation of the heat-meltable ink layer and the coating amount regulation of the heat-meltable ink layer, the total amount of the heat-meltable ink which is melted by the heat energy from the heat-generating element and becomes liquid corresponds to the heat-generating element. It is possible to divide and invade into all the pores within the area.

In the present invention, the melt viscosity is a value measured by using a rheometer MR-300 manufactured by Rheology Co., Ltd.

Therefore, according to the present invention, a predetermined amount of the heat-meltable ink can be surely allowed to enter the pores in the area corresponding to the heat generating element, and problems such as overtransfer will not occur. As a result, it is possible to obtain a color image having good gradation and exhibiting desired subtractive color mixture and having excellent color reproducibility and resolution.

When the melt viscosity of the heat-meltable ink layer for each color is higher than the above range, the heat-meltable ink is unlikely to enter the pores, and overtransfer is likely to occur. On the other hand, when it is lower than the above range, the heat-meltable ink spreads, the pixels are connected, and the resolution becomes poor.

If the coating amount (calculated as solid content) of the heat-meltable ink layer of each color is larger than the above range, overtransfer is likely to occur,
On the other hand, when the amount is less than the above range, the density of each color is insufficient.

If the thickness of the base material and the thickness of the thermal transfer recording medium are larger than the above ranges, respectively, the resolution is lowered. If the thickness of the base material and the thickness of the thermal transfer recording medium are smaller than the above-mentioned ranges, the strength of the ink ribbon is insufficient, or the density of each color is insufficient due to the limitation of the coating thickness of the heat-meltable ink layer. .

The heat-fusible ink layer of each color is composed of a colorant and a heat-fusible vehicle. As the heat-fusible vehicle, a wax substance is mainly used, and if necessary, a hot-melt resin is blended. it can.

Examples of the wax substances include natural waxes such as wood wax, beeswax, lanolin, carnauba wax, candelilla wax, montan wax and ceresin wax; petroleum waxes such as paraffin wax and microcrystalline wax; oxidation waxes and esters. Synthetic waxes such as wax, low molecular weight polyethylene and Fischer-Tropsch wax; higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid; higher aliphatic alcohols such as stearyl alcohol and docosanol; higher aliphatic monoglycerides Esters such as sugar fatty acid esters and sorbitan fatty acid esters; one or a mixture of two or more such as amides such as oleylamide and bisamides can be used. That.

Examples of the heat-meltable resin include ethylene-vinyl acetate copolymer, ethylene-vinyl butyrate copolymer, ethylene- (meth) acrylic acid copolymer, ethylene- (meth) acrylic acid alkyl ester copolymer. Combined (as the alkyl group, methyl, ethyl, propyl, butyl,
Hexyl, heptyl, octyl, 2-ethylhexyl,
Nonyl, dodecyl, hexadecyl and the like having about 1 to 16 carbon atoms), ethylene-acrylonitrile copolymer, ethylene-acrylamide copolymer, ethylene-N-methylolacrylamide copolymer, ethylene-styrene copolymer Ethylene-based copolymers such as; Poly (meth) acrylic acid esters such as polylauryl methacrylate and polyhexyl acrylate; Chlorination of polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl alcohol copolymer, etc. Vinyl (co) polymer; Other polyester resin, polyamide resin, cellulose resin, natural rubber, styrene-butadiene copolymer, isoprene polymer, chloroprene polymer, petroleum resin, rosins, terpene resin, coumarone-indene resin 1 or 2 such as Mixtures of more can be used.

Yellow used for the heat-meltable ink layer,
A transparent colorant is preferably used as the magenta and cyan colorants.

Examples of the yellow transparent coloring agent include Naphthol Yellow S, Hansa Yellow 5G, Hansa Yellow 3G, Hansa Yellow G, Hansa Yellow GR, Hansa Yellow A, Hansa Yellow RN, Hansa Yellow R, Benzidine Yellow, Benzidine Yellow G and Benzidine Yellow G.
One or two of organic pigments such as R, permanent yellow NCG, and quinoline yellow lake, and dyes such as auramine
More than one seed is used.

As the magenta transparent coloring agent, for example, Permanent Red 4R, Brilliant Fast Scarlet, Brilliant Carmine BS, Permanent Carmine FB, Resole Red, Permanent Red F5.
One or more of organic pigments such as R, brilliant carmine 6B, pigment scarlet 3B, rhodamine lake B, rhodamine lake Y, and alizarin lake, and dyes such as rhodamine are used.

As the cyan transparent colorant, for example, one or more of organic pigments such as Victoria blue lake, metal-free phthalocyanine blue, phthalocyanine blue and fast sky blue, and dyes such as Victoria blue can be used. Used.

Here, the transparent colorant means a colorant which gives a transparent hot-melt ink when dispersed in a transparent vehicle.

It should be noted that three of yellow, magenta and cyan
When it is difficult to obtain a clear black color by superimposing colors, for example, a black heat-meltable ink layer containing a black colorant such as carbon black or nigrosine base may be used. The black heat-meltable ink layer for such a purpose does not need to be transparent because it does not overlap with other color heat-meltable ink layers. However, it is preferable that the black heat-melting ink layer for the purpose of obtaining a color such as blue black by being superposed on the heat-melting ink layer of another color is transparent.

The content of the colorant in the heat fusible ink layer is preferably about 5 to 60% by weight.

If necessary, a dispersant, an antistatic agent, etc. may be added to the heat-meltable ink layer.

The melting temperature of the heat-meltable ink layer is 50 to 90.
C., and above all about 60 to 85.degree. C. are preferable. When the melting temperature is lower than the above range, the storage stability of the thermal transfer recording medium tends to be poor, while when it is higher than the above range, the transfer sensitivity tends to decrease.

The thermal transfer recording medium of the present invention is one in which the heat-melting ink layers of the respective colors are provided on a substrate. The yellow heat-melting ink layer, the magenta heat-melting ink layer and the cyan heat-melting ink layer are used. Ink layer, and optionally a black hot-melt ink layer, may be provided on separate substrates, or these hot-melt ink layers may be provided side by side on a single substrate.

FIG. 5 shows an example of a thermal transfer recording medium in which heat-meltable ink layers of respective colors are arranged side by side on a single substrate. In FIG. 5, a yellow heat-meltable ink layer 3Y, a magenta heat-meltable ink layer 3M, and a cyan heat-meltable ink layer 3C having a certain size are arranged on the base material 2 in a certain order. It is repeatedly arranged as one repeating unit U. The order of arranging the three color heat-meltable ink layers in the repeating unit U can be arbitrarily selected. A black heat-meltable ink layer may be added to the repeating unit U.

Alternatively, a yellow heat-meltable ink layer, a magenta heat-meltable ink layer, and a cyan heat-meltable ink layer, and if necessary, a black heat-meltable ink layer, are used as a base material on a single base material. You may provide in the shape of a stripe along the length direction.

As the substrate, a polyethylene terephthalate film, a polyethylene naphthalate film,
Polyester film such as polyarylate film,
Polycarbonate film, polyamide film, aramid film, and other various plastic films generally used as a substrate film for this kind of ink ribbon can be used. Also, high density thin paper such as condenser paper may be used. Silicone resin, fluororesin, nitrocellulose resin, or various heat-resistant resins such as silicone-modified urethane resin and silicone-modified acrylic resin modified by these on the back surface of the base material (the surface that is in contact with the thermal head), or A conventionally known stick-preventing layer formed of a mixture of these heat-resistant resins with a lubricant may be provided.

To form a color image on a transparent film by using the thermal transfer recording medium of the present invention, a color transfer image signal of a color image, that is, a yellow signal, is generated by a thermal transfer printer.
According to the magenta signal and the cyan signal, the yellow heat-meltable ink layer, the magenta heat-meltable ink layer, and the cyan heat-meltable ink layer are sequentially and selectively melt-transferred, and the pores of the surface porous image receptor are obtained. Let the heat-melting ink of each color infiltrate into. The transfer order of the yellow heat-meltable ink layer, the magenta heat-meltable ink layer, and the cyan heat-meltable ink layer can be arbitrarily selected. In the case of a normal color image, all of the three heat-meltable ink layers are selectively transferred according to the color signals of three colors, but when there are only one or two color signals, the corresponding one or two The color heat-meltable ink layer is selectively transferred.

Thus, (1) a monochromatic area consisting of one color without color overlap, (2) an area where colors are developed by subtractive color mixing of two or three colors, or (3) the above (1) and (2) )
A color image consisting of the union area of is obtained. here,
In the area where the yellow heat-melting ink and the magenta heat-melting ink are present in the pores, the red color is present, and the yellow heat-melting ink and the cyan heat-melting ink are present in the pores. The green color is in the area, and the blue color is in the area where the magenta heat-meltable ink and the cyan heat-meltable ink are present in the pores. A black color is exhibited in the portion where the heat-meltable ink is present in the pores. Yellow, magenta, or cyan color is exhibited in the portions where only the yellow heat-meltable ink, magenta heat-meltable ink, or cyan heat-meltable ink is present in the pores, respectively.

In the above description, the black color is obtained by superimposing the yellow heat-melting ink, the magenta heat-melting ink and the cyan heat-melting ink, but the black color is obtained without using the three color heat-melting inks. The black color may be obtained by using only the heat-meltable ink.

To obtain a gradation color for each color, the transfer amount of the heat-melting ink of each color may be controlled to adjust the amount of penetration of the heat-melting ink of each color into the pores.

The transparent film that can be used in the present invention is provided with a porous layer on the surface, and the average diameter of the fine pores is 0.1 to 10 μm, especially 0.5.
˜5 μm with a density of 5 × 10 ⁵ to 1 × 10 ⁷ pieces / mm
² , above all 8 × 10 ⁵ to 8 × 10 ⁶ pieces / mm ² ,
Average depth 0.5 to 15 μm, especially 2 to 10 μm
It is preferred that If the average diameter is larger than the above range, the resolution of the printed image tends to be poor, while if it is smaller than the above range, it tends to be difficult for ink to penetrate. Further, if the average depth is deeper than the above range, it tends to be difficult to maintain the strength of the transparent film as a porous layer, while if it is shallower than the above range, a desired amount of ink penetrates. Tends to be unable to. When the density is higher than the above range, the area occupied by the micropores is about 75% or more with respect to the surface of the transparent film, so that the strength of the transparent film as a porous layer is maintained. If it is lower than the above range, the resolution of the printed image tends to decrease.

In the present invention, the diameter of the fine pores of the porous layer,
The depth of the fine pores and the density of the fine pores are values measured using a photograph taken by a scanning electron microscope (JSM / T-20 manufactured by JEOL Ltd.). The diameter of the micropores was determined by randomly selecting a 20 μm square (substantial dimension of the porous layer) area from the above photograph taken at a magnification of 2000 and determining the average value of the diameter of the micropores contained in this area. Take the measurement value. Also,
The density of the fine holes is measured as the number per unit area by counting the number of the fine holes included in the same area of the same photograph as that used for measuring the fine holes. For the depth of the micropores, randomly select a portion with a width of 20 μm from the cross-sectional photograph taken at a magnification of 2000 times of the porous layer, and average the depth of the micropores included in this width in the cross-sectional photograph. The value is taken as the measured value ((average) diameter of micropores, density of micropores,
The measuring method of the (average) depth of the micropores is the same below.)

The transparent film can be used without particular limitation as long as it is a highly transparent film such as a polyester film such as polyethylene terephthalate, polyethylene naphthalate or polyarylate.

The transparent film C, which has fine pores on one surface, is not particularly limited. For example, a highly transparent film made of the above-mentioned material may be used as a transparent film. It can be manufactured by a method of laminating thin films having high fine pores.

FIG. 6 is a schematic partial cross-sectional view of a transparent film obtained by thermally transferring an arbitrary image-shaped color image by the above method using the above thermal transfer recording medium (of course, in the manufacturing method of the present invention. , May be a monochrome image). In FIG. 6, 4 is a transparent film, 5 is fine holes, 6 is a space, 3Y is a yellow heat-melting ink, and 3M.
Indicates a magenta heat-melting ink, and 3C indicates a cyan heat-melting ink. On the transparent film 4, the yellow heat-melting ink 3Y, the magenta heat-melting ink 3M, and the cyan heat-melting ink 3C are superposed and transferred in this order, and the yellow heat-melting ink 3Y, There are fine holes 5 in which the magenta heat-melting ink 3M is transferred in this order and fine holes 5 in which no heat-melting ink of any color is transferred (actually, a single color or each color of the heat-melting ink is melted). (There are other combinations of the heat-meltable inks, and there are various combinations of the amount of the heat-meltable ink to be transferred. Therefore, it is not limited to the combination of the heat-meltable inks shown in FIG. 6).

Further, in FIG. 6, the transparent film 4 has an air layer in which the heat-melting ink does not penetrate to the deep portion of the fine holes and a fine hole in which the heat-melting ink does not penetrate. In addition, when diffuse reflection of light occurs, and when it is used as an OPH film in this state,
High-definition images cannot be projected on the screen.
Therefore, in order to obtain a high-definition screen image, it is necessary to seal the air holes and the fine pores into which the heat-fusible ink has not entered.

In FIG. 7, a colorless and transparent ink layer 7 is provided on one surface, which is used to press the colorless and transparent ink into the transparent film on which the color image is transferred under heat and pressure. The base material 8 is shown.

As shown in FIG. 8, the transparent film on which the color image is transferred and the colorless and transparent ink layer 7 are formed.
After overlaying the base material 8 on which the colorless transparent ink layer 7 and the image face each other,
By heating and pressurizing, in the fine holes 5 in which the heat-melting inks 3Y, 3M and / or 3C of the respective colors of the transparent film do not penetrate deeply, the colorless and transparent ink 7 is the heat-melting ink 3Y, 3M and / or 3C are pressed to penetrate deep into the fine holes 5, and the colorless and transparent ink 7 also penetrates into the fine holes 5, and the heat-melting inks 3Y, 3M and 3C of the respective colors do not penetrate into the fine holes 5. Hole 5
In this case, since the colorless and transparent ink 7 penetrates deep into the fine holes, the colorless transparent ink and the hot-melt inks of the respective colors are filled in the spaces 6 and the fine holes in which the hot-melt inks of the respective colors have not entered. Can be filled with. Subsequently, by peeling off the base material 8, the heat-melting ink and / or the colorless and transparent ink penetrates deep into the fine holes (see FIG. 8) as shown in FIG. A film for OHP having an image of can be produced.

The heating and pressurizing is performed, for example, by a laminator at a heating temperature of 100 to 250 ° C., preferably 120 to 200 ° C., 1 to 25 Kgf / cm ² , preferably 5 to ²
A method of heating and pressing once or a plurality of times (usually about twice) under the condition of a pressure of 5 Kgf / cm ² can be mentioned.

In FIG. 7, the colorless and transparent ink applied to one surface of the base material 8 is not particularly limited, but examples thereof include paraffin wax, carnauba wax, candelilla wax, and microcrystalline wax. One or a mixture of two or more of waxes such as wax, oxide wax, polyethylene wax and the like, ethylene-vinyl acetate copolymer resin, ethylene acrylate copolymer resin, polyamide resin, epoxy resin and the like can be used. Paraffin wax, microcrystalline wax, polyethylene wax, ethylene-vinyl acetate copolymer resin, ethylene acrylate copolymer resin and the like are preferable from the viewpoint of excellent transparency.

The melting temperature of the colorless and transparent ink layer is 5
The temperature is preferably 0 to 90 ° C, especially 60 to 85 ° C.
If the melting temperature is lower than the above range, the storage stability tends to be poor, while if it is higher than the above range, the transfer sensitivity tends to be low, resulting in poor transfer.

The wax and / or resin is dissolved in an appropriate solvent to obtain a coating liquid, and the coating liquid is applied on one surface of the substrate 8 and dried to obtain a transparent ink layer 7.

The coating amount (weight after drying) of the transparent ink layer 7 is 1 to 10 g / m ² , especially 3 to 8 g / m ^2.
Is preferred. If the coating amount is less than the above range, the transparent ink cannot sufficiently penetrate into the fine pores, so that the OHP film having a high-definition image with improved transparency tends to be unable to be obtained, while the amount is more than the above range. Then, an extra transparent ink flows at the time of lamination to stain the OHP film itself having the high-definition image or stain the peripheral devices, which tends to cause a problem in workability.

The same material as the thermal transfer recording medium can be used as the substrate 8 for the same reason.

If the releasability between the base material 8 and the colorless and transparent ink 7 is poor, a release layer may be provided between the base material 8 and the transparent ink layer 7.

The method of press-fitting a colorless and transparent ink into a transparent film having the color image transferred thereon under heating and pressurization is one embodiment of the present invention. Examples include a method of directly coating a film with a colorless and transparent ink and then press-fitting it under heating and pressurization.

[0061]

【Example】

Example 1 Vinyl chloride-vinyl acetate copolymer resin (Sekisui Chemical Co., Ltd.)
Manufactured by Elex C), a solution prepared by dissolving 100 parts by weight of DMF in 400 parts by weight of acrylic resin (Toho Rayon Co., Ltd.)
Manufactured by Bethlon V-241) 100 parts by weight of DMF400
A solution prepared by mixing 100 parts by weight of a solution of polyvinyl butyral resin (Elex BMS manufactured by Sekisui Chemical Co., Ltd.) in 400 parts by weight of DMF at a ratio of 9: 5: 2 was used. Kaisho 63-17
According to the method described in Japanese Patent No. 0438, thickness 1
An image-receiving coat layer having fine pores was provided on a transparent polyethylene terephthalate film (hereinafter, simply referred to as PET film) having a thickness of 00 μm. The average depth of the fine pores of the image-receiving coating layer provided on the PET film is 8.0 μm,
The density is 1.0 × 10 ⁶ pieces / mm ² , and the average diameter is 1.0.
μm. Next, a thermal transfer recording medium for color image formation (a yellow heat-meltable ink, a magenta heat-meltable ink and a cyan heat-meltable ink is provided on the surface of the substrate) is used for the image-receiving coat layer. A color image was transferred using a thermal transfer printer (CP-2200, manufactured by Victor Company of Japan, Ltd.). The melting temperature and the melting viscosity of the heat-meltable ink of the heat transfer recording medium for color image formation are 67 ° C. and 16 ° C. for the yellow heat-meltable ink, respectively.
It was 5 cps / 90 ° C., the magenta hot melt ink was 66 ° C. and 140 cps / 90 ° C., and the cyan hot melt ink was 73 ° C. and 160 cps / 90 ° C.

On the other hand, a base material (100 μm thick white polyethylene terephthalate film) was coated with an ink of the following formulation to obtain a colorless and transparent ink layer having a coating amount of 5 g / m ^2. The colorless and transparent ink layer Had a melting temperature of 70 ° C and a melt viscosity of 600 cps / 90 ° C.

(Colorless and transparent ink formulation) Paraffin wax (melting temperature 70 ° C.) 80 parts by weight Ethylene-vinyl acetate copolymer resin (softening point 53 ° C.) 20 parts by weight To the PET film on which the color image is transferred. The base material provided with the colorless and transparent ink layer is laminated so that the colorless and transparent ink layer and the color image face each other, and two layers are formed by using Lami Packer LPD-280 manufactured by Fuji Plastics Co., Ltd. This laminate is rolled between rolls at 190 ° C and 20K
The operation of passing under the condition of gf / cm ² was repeated twice, and then the base material was peeled off to prepare an OHP film having a high definition image of the present invention.

When the fineness of the projected image by OHP of this OHP film was visually evaluated, it was almost the same level as the image projected using a slide photograph.

Comparative Example 1 OH prepared by the same method as in Example 1 except that the transparent PET film was not provided with the image receiving coating layer.
The OHP projected image of the P film and the image projected using the same slide photograph as in Example 1 were visually evaluated for comparison.
The projected image of P was clearly inferior in definition as compared with the image projected using the slide photograph.

[0066]

According to the first aspect of the invention, in a method for producing an OHP film having an image by thermally transferring the image onto the transparent film using a thermal transfer recording medium, the image on the transparent film is thermally transferred. A porous layer is provided on the surface of the porous layer, and the image is thermally transferred onto the surface on the side of the porous layer by using a thermal transfer recording medium so that the heat-meltable ink is applied to the micropores of the porous layer to form an arbitrary image. After infiltrating into the micropores, the colorless and transparent ink is further pressed into the micropores under heat and pressure. The hot melt ink is pressed into the deep part of the fine hole by the invasion pressure of the ink and the colorless transparent ink is pressed in, and the colorless transparent ink is filled in the fine hole where the hot melt ink does not enter. By causing pressed until parts to improve the transparency of the film can obtain OHP film having a high definition image, according to the OHP film,
A high-definition image can be projected on the screen.

According to a second aspect of the present invention, in the first aspect of the present invention, the colorless and transparent ink is press-fitted into a substrate having a colorless and transparent ink layer on one surface thereof. When the ink layer and the porous layer are overlapped with each other and heated and pressed so as to face each other, the base material serves as a cushion layer, and the transparent ink and the heat are applied as uniformly as possible to heat and pressure. In order to add to the fusible ink, the colorless and transparent ink is sufficiently pressed into the spaces or the fine pores into which the hot fusible ink has not entered, and when the substrate is peeled off, the colorless and transparent ink is easily Since the colorless transparent ink layer having a smooth surface is formed on the OHP film due to the peeling of the substrate, an OHP film having a higher definition image can be obtained.
With the HP film, it is possible to project a higher definition image on the screen.

According to a third aspect of the present invention, in the second aspect, when the releasability between the substrate and the colorless and transparent ink is poor, a releasability is provided between the substrate and the transparent ink layer. By providing the layer, the substrate can be easily peeled off from the colorless and transparent ink layer transferred to the OHP film side, and therefore the surface of the colorless and transparent ink layer is smooth, An OHP film having a high-definition image can be obtained, and the OHP film can project a high-definition image on a screen.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of a thermal transfer recording medium used for transferring an arbitrary image-like printed image on a transparent film having fine holes which can be used in the method of the present invention.

FIG. 2 is a schematic partial cross-sectional view of a transparent film that can be used in the method of the present invention.

FIG. 3 is a schematic sectional view for explaining a method for transferring an arbitrary image-shaped printed image onto a transparent film which can be used in the method of the present invention.

FIG. 4 is a schematic partial cross-sectional view of a transparent film having fine holes in which a color image in which a yellow ink and a magenta ink are superimposed is formed.

FIG. 5 is a schematic partial cross-sectional view showing an example of a thermal transfer recording medium for color image formation that can be used in the method of the present invention.

FIG. 6 is a schematic partial cross-sectional view for explaining a transparent film in which a hot-melt ink has penetrated into fine pores that can be used in the method of the present invention to form an arbitrary image-shaped color image.

FIG. 7 shows a substrate having a colorless and transparent ink layer on one surface, which is used to press a colorless and transparent ink into a transparent film on which a color image is transferred under heat and pressure. Shows.

8 is a plan view of the base material having a colorless and transparent ink layer formed on its surface in the production method of the present invention, which is superposed on the transparent film having an arbitrary image-like color image shown in FIG. FIG. 4 is a schematic partial cross-sectional view for explaining a method for producing a film for OHP having a high-definition image by heating and pressurizing from the surface direction to fill the micropores and the spaces in the micropores by press-fitting colorless and transparent ink. .

9 is a schematic partial cross-sectional view of a film for OHP having a high-definition image according to the present invention, which is manufactured by the manufacturing method described in FIG.

[Explanation of symbols]

1 Thermal Transfer Recording Medium 2 Base Material 3 Thermal Melt Ink Layer 3a Thermal Melt Ink Transferred to Transparent Film 3Y Yellow Thermal Melt Ink 3M Magenta Thermal Melt Ink 3C Cyan Thermal Melt Ink 4 Transparent Film 5 Micropores 6 Space 7 Colorless and transparent ink layer 8 Substrate 9 Colorless and transparent ink transferred to the transparent film side T Thermal head P Platen U Repeating unit

Claims (3)

[Claims] 1. A method for producing an overhead projector film having an image by thermally transferring an image onto a transparent film using a thermal transfer recording medium, wherein a porous film is provided on the surface of the transparent film on which the image is thermally transferred. A porous layer is provided, and after the image is thermally transferred onto the surface of the porous layer using a thermal transfer recording medium, the heat-meltable ink is intruded into the fine pores of the porous layer in an arbitrary image form, A method for producing a film for an overhead projector having a high-definition image, characterized in that colorless and transparent ink is further pressed into the fine pores under heating and pressure. 2. A substrate having a colorless and transparent ink layer provided on one surface thereof is superposed and heated under pressure so that the colorless and transparent ink layer and the porous layer face each other to form fine pores. The method for producing a film for an overhead projector having a high-definition image according to claim 1, further comprising press-fitting a colorless and transparent ink. 3. The method for producing a film for an overhead projector having a high-definition image according to claim 2, wherein a release layer is provided between the colorless and transparent ink layer and the base material.