JP3308387B2 - Thermal transfer image receiving sheet - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving sheet, and more particularly, to an object of the present invention is to provide a plain paper-like thermal transfer image-receiving sheet on which a high-density and high-resolution image is formed.

[0002]

2. Description of the Related Art Various thermal transfer methods have been conventionally known. Among them, a sublimable dye is used as a recording agent, and this is carried on a base sheet such as paper or a plastic sheet to form a thermal transfer sheet. There have been proposed methods for forming various full-color images on a thermal transfer image-receiving sheet that can be dyed with a dye, for example, a thermal transfer image-receiving sheet provided with a dye-receiving layer on the surface of paper or a plastic film.

In this case, a thermal head of a printer is used as a heating means, and a large number of color dots of three or four colors are transferred to a thermal transfer image receiving sheet by heating for a very short time, and the multicolored dots are used to copy an original. Is reproduced. The image formed in this way is
It is very clear because the coloring material used is a dye,
And, because of its excellent transparency, the resulting image is excellent in the reproducibility and gradation of intermediate colors, similar to images by conventional offset printing or gravure printing, and has high quality images comparable to full-color photographic images. It can be formed.

As the thermal transfer image receiving sheet used in the above-described sublimation type thermal transfer system, a plastic sheet, a laminated sheet of a plastic sheet and paper, a synthetic paper, and the like are used. In order to expand to general offices, it is required to use plain paper such as coated paper (art paper), cast coated paper, and PPC paper as a base sheet of a thermal transfer image receiving sheet.

When such a general office paper is used as a base sheet and a dye-receiving layer is formed on the surface thereof, the dye-receiving layer and the base sheet are combined with each other in order to give the thermal transfer image-receiving sheet a sense of quality. An intermediate layer is provided therebetween, and a white pigment and a fluorescent whitening agent are contained in the intermediate layer to eliminate yellowing of paper as a base sheet. In addition, in order to reduce the glossiness of the dye receiving layer and to provide a plain paper feeling, inorganic fine particles may be contained in the dye receiving layer, or heat and pressure may be applied to the surface of the dye receiving layer by embossing rolls to impart fine irregularities. It has also been proposed to impart a matte feeling by using the same.

[0006]

[Problems to be solved by the invention]
In the above-mentioned conventional method, for example, when inorganic fine particles are added to the dye receiving layer, there is a problem that the transferability of the dye is reduced or transfer unevenness occurs due to the mixing of the inorganic fine particles. In addition, in the case of the embossing method, the resin in the receiving layer is degraded by heat during the embossing process, white spots are generated at the time of transfer, and the productivity and cost due to the complicated process. Occurs. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and to provide a plain paper-like thermal transfer image receiving sheet on which a high-density and high-resolution image is formed.

[0007]

The above object is achieved by the present invention described below. That is, the present invention provides a thermal transfer image-receiving sheet in which a bubble-containing layer, an intermediate layer, and a dye-receiving layer are sequentially laminated on at least one surface of a substrate sheet, wherein the intermediate layer contains titanium oxide particles and talc particles. Only, oxidized titan
Weight ratio between the iron particles and the talc particles is 10/90 to 90/1.
0, and the total weight of both is 10%.
The thermal transfer image-receiving sheet is characterized by being 10 to 500 parts by weight per 0 parts by weight .

[0008]

Function: By adding titanium oxide particles and talc particles to the intermediate layer of a thermal transfer image receiving sheet, the hue and glossiness of the dye receiving layer can be freely controlled without lowering the original function of the dye receiving layer. Thus, a plain paper-like thermal transfer image-receiving sheet on which a high-density and high-resolution image is formed can be provided. That is, since the titanium oxide particles and the talc particles do not exist in the dye receiving layer, the original performance of the dye receiving layer does not decrease. The yellowing of the substrate sheet is concealed by the high concealing property of titanium oxide, a moderate matte feeling is imparted by the talc particles, and in a more preferred embodiment, the yellowness of the dye receiving layer itself is added by adding a fluorescent whitening agent. It is erased and whiteness can be increased.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. The base sheet used in the present invention is not particularly limited, and any of resin films, sheets, a laminate thereof, a sheet obtained by laminating a foamed resin sheet on one side or both sides using natural paper as a core material may be used. I can do it. However, not only the receiving layer surface,
When the texture of plain paper is required including the back side, natural pulp such as high quality paper, kraft paper, heat transfer paper, finely coated paper, lightweight coated paper, coated paper, art paper, cast coated paper, etc. is mainly used. It is preferable to use a paper base that has been used.
It is advantageous in terms of cost to use natural pulp paper as a paper base.

[0010] At least one surface of the above-mentioned substrate sheet
The intermediate layer formed via the bubble-containing layer is a resin layer containing titanium oxide particles and talc particles. Examples of suitable resins for forming the intermediate layer include thermoplastic resins such as polyurethane resins, acrylic resins, polyester resins, and polycarbonate resins, or partially crosslinked resins thereof, crosslinkable polyurethane resins, epoxy resins, and melamine. Thermosetting resins such as resin and urea resin. Titanium oxide particles include rutile type and anatase type, rutile type is a slightly yellowish white pigment, and anatase type is a slightly bluish white pigment, matching the color tone required for thermal transfer image receiving sheets. It is preferable to use them properly. The talc particles are translucent white particles with a slightly yellow tint and, unlike titanium oxide, have a low concealing property, but can reduce the gloss of the dye receiving layer formed and give a matt feeling of plain paper. .

[0011] range of weight ratio 10 / 90-90 / 10 of the titanium oxide particles and talc particles to be added to the intermediate layer der
And the range of 30/70 to 70/30 is preferable. If the amount of talc particles is too small, the matte feeling of the dye-receiving layer formed will be insufficient, while if the amount of titanium oxide particles is too small, it will not be possible to hide the yellowness of the base sheet as the base. The amount of both used is 10 to 500 parts by weight, preferably 50 to 400 parts by weight, per 100 parts by weight of the resin forming the intermediate layer in total weight. If the total amount of the two is too small, the matte feeling of the formed dye receiving layer is insufficient, and the effect of hiding the base is insufficient. On the other hand, if the total amount of both is too large, problems arise in dispersion stability and coating properties of the coating solution for the intermediate layer, and further, strength of the formed film and the like.

In the present invention, if necessary, a fluorescent whitening agent may be further added to the intermediate layer. When using a fluorescent whitening agent, 0.01 parts by weight per 100 parts by weight of the resin forming the intermediate layer.
A ratio of 10 to 10 parts by weight is preferred. If the amount of the fluorescent whitening agent is too small, the whitening effect does not appear, on the other hand, even if it is added in a large amount, the appropriate whitening effect is not obtained, resulting in a purple hue,
Moreover, it is not preferable in terms of cost.

The intermediate layer is formed by dissolving and dispersing the above resin and additives in a suitable organic solvent such as acetone, ethyl acetate, methyl ethyl ketone, toluene, xylene, cyclohexanone, etc. to prepare a paint or ink. Is applied and dried on at least one surface or the bubble-containing layer of the substrate sheet by forming means such as a gravure printing method, a screen printing method, a reverse roll coating method using a gravure plate, and further, if necessary. Crosslink and cure to form an intermediate layer. The thickness of the intermediate layer formed in this way is about 0.5 to 10 g / m ^{2 in} terms of solid content coating amount,
More preferably, it is 1 to 6 g / m ² . If the thickness is too small, the performance required for the intermediate layer cannot be obtained. On the other hand, if the thickness is too large, the effect as the intermediate layer will not be improved any more and the cost will be unfavorable.

The dye-receiving layer formed on the surface of the intermediate layer is for receiving the sublimable dye transferred from the thermal transfer film and maintaining the formed image. Examples of the resin for forming the dye receiving layer include polyolefin resins such as polypropylene, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer, and halogenated polymers such as polyvinylidene chloride. ,
Polyvinyl acetate, vinyl polymers such as polyacrylic ester, polyethylene terephthalate, polyester resins such as polybutylene terephthalate, polystyrene resins, polyamide resins, copolymer resins of olefins such as ethylene and propylene and other vinyl monomers, Examples thereof include cellulose resins such as ionomers and cellulose diacetates, and polycarbonates. Particularly preferred are vinyl resins and polyester resins.

Preferred release agents used by mixing with the above resins include silicone oil, phosphate ester surfactants, fluorine surfactants, etc., but silicone oil is preferred. As the silicone oil, a modified silicone oil such as epoxy-modified, alkyl-modified, amino-modified, carboxyl-modified, alcohol-modified, fluorine-modified, alkylaralkyl-polyether-modified, epoxy / polyether-modified, or polyether-modified is preferred.

One or more release agents are used. The amount of the release agent is preferably 0.5 to 30 parts by weight based on 100 parts by weight of the resin for forming the dye receiving layer. If the addition amount is not satisfied, problems such as fusion between the thermal transfer film and the dye receiving layer or reduction in printing sensitivity may occur. By adding such a releasing agent to the dye receiving layer, the releasing agent bleeds out on the surface of the receiving layer after transfer to form a releasing layer.

The receptor layer is formed by dissolving the above-mentioned resin obtained by adding necessary additives such as a releasing agent to the surface of the above-mentioned intermediate layer in an appropriate organic solvent or dispersing it in an organic solvent or water. The dispersion thus obtained is formed by applying and drying by a forming means such as a gravure printing method, a screen printing method, and a reverse roll coating method using a gravure plate. The dye-receiving layer formed as described above may have any thickness, but generally has a thickness of 1 to 50 μm. or,
Such a dye receiving layer is preferably a continuous coating,
A discontinuous coating may be formed using a resin emulsion or a resin dispersion.

In the present invention, to form a bubble-containing layer between the front and Kimotozai sheet said intermediate layer. Such a bubble-containing layer is composed of bubbles and a binder. As the binder, any resin such as a resin in an aqueous emulsion dispersion system can be used.

The bubbles contained in these resins are formed from a foaming agent. Examples of such foaming agents include dinitropentamethylenetetramine, diazoaminobenzene which decomposes by heat to generate gases such as oxygen, carbon dioxide and nitrogen. Decomposition type foaming agents such as azobisisobutyronitrile and azodicarbonamide, and known foaming agents such as microspheres obtained by microencapsulating a low boiling point liquid such as butane and pentane with a resin such as polyvinylidene chloride and polyacrylonitrile. Any of them can be used, and a foam obtained by foaming these microspheres in advance, a microsphere coated with a white pigment, and the like can also be used effectively. These foaming agents may be in a foamed state in the resin, in an unfoamed state, or in an intermediate state.

The amount of the foaming agent or foam used is such that the foaming ratio (thickness after foaming / thickness before foaming) of the cell-containing layer is 1.
It is preferable to use the resin in a ratio of about 5 to 20 times, for example, 0.5 to 50 parts by weight per 100 parts by weight of the resin forming the bubble-containing layer. The foaming of the foaming agent may be performed before or during the formation of the bubble-containing layer, or may be performed after the formation of the dye-receiving layer transfer film as described later, or may be performed during the transfer of the dye-receiving layer. A transfer may be performed together with the receiving layer or the like on a base sheet in an unfoamed state, and then foamed by heat when forming an image with a thermal head.
These foaming times can be freely determined by selecting a foaming agent, a temperature at the time of transferring the dye receiving layer, and the like. In the above, the microcapsule foaming agent such as microspheres is particularly preferable since the bubbles have an outer wall even after foaming, so that defects such as pinholes do not occur in the resin layer, the intermediate layer, and further the receiving layer. . These bubble-containing layers are preferably formed to a thickness of about 0.5 to 30 μm.

As described above, the thermal transfer image-receiving sheet of the present invention comprises:
As described above, each layer can be formed by sequentially coating the base sheet.However, when the base sheet is pulp paper such as plain paper having a coarse surface, it can be formed by a transfer method. preferable. For rough pulp paper,
In the coating method, it is difficult to impregnate the pulp paper unevenly with the coating liquid to form a uniform layer, but the transfer method can easily avoid such a problem. The receiving layer transfer film used in the transfer method is one in which a dye receiving layer, an intermediate layer and a bubble-containing layer or a resin layer are laminated on one surface of a substrate film in the order described above in a releasable manner.

Prior to the formation of the receiving layer, a release layer may be formed on the surface of the base film. Such a release layer is formed from a release agent such as a wax, a silicone wax, a silicone resin, a fluorine resin, and an acrylic resin. The forming method may be the same as the above-described method for forming the receiving layer, and the thickness thereof is set to 0.1.
About 5 to 5 μm is sufficient. If a matte receiving layer is desired after transfer, the release layer may be made into a matte surface by incorporating various particles in the release layer or using a base film having a matte surface on the release layer side. I can do it.
Needless to say, when the base film has an appropriate peeling property, the release layer need not be formed. The method for forming the bubble-containing layer, the intermediate layer, the dye-receiving layer and the like are the same as described above.

In the transfer method of the receiving layer, an ordinary laminator can be advantageously used as it is, and examples of the laminating means include dry lamination, wet lamination, extrusion lamination and hot melt lamination.

[0024]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, parts or% are based on weight unless otherwise specified. First, synthetic paper (manufactured by Oji Yuka, thickness 110 μm) was used as the base sheet 1 and coated paper (manufactured by Oji Paper, OK coat, basis weight 12) was used as the base sheet 2.
7.9 g / m ² ).

Further, the following coating liquids were prepared for forming each layer. Bubble-containing layer coating solution 1; emulsion (Japan Synthetic Rubber Ltd., AE120) 100 parts foamable microcapsules (F-30, Matsumoto Yushi Seiyaku Co., Ltd.) Coating solution 1 for 30 parts of pure water 30 parts The intermediate layer; acrylic Resin (manufactured by Mitsubishi Rayon, BR-85) 100 parts Titanium oxide (manufactured by Tochem Products, TCA-888) 100 parts Talc (manufactured by Maruo Calcium, LMR # 200) 100 parts Toluene / methyl ethyl ketone (weight ratio 1/1) 900 parts

Coating solution 2 for intermediate layer : polyurethane resin (manufactured by Mitsui Toatsu, N2249E) 100 parts Titanium oxide (manufactured by Ishihara Sangyo, TT-055 (A)) 150 parts Talc (manufactured by Nippon Talc) 100 parts Fluorescent brightening Agent (Ciba Geigy, Ubitex OB) 0.05 part Ethyl acetate 600 parts Coating solution 3 for middle layer ; Polyester resin (Toyobo, Byron 600) 100 parts Titanium oxide (Ishihara Sangyo, TT-055 (A)) 100 parts Talc (manufactured by Nippon Talc) 150 parts Optical brightener (manufactured by Ciba-Geigy, Ubitex OB) 0.1 part Methyl ethyl ketone / toluene (weight ratio 1/1) 900 parts

The intermediate layer coating solution 4; polyester resin (manufactured by Toyobo Co., Byron 600) 100 parts Titanium oxide (Tochem Products Ltd., TCA-888) 100 parts Methyl ethyl ketone / toluene (1/1 by weight) 400 parts of the intermediate layer use coating liquid 5; acrylic resin (manufactured by Mitsubishi Rayon Co., BR-85) 100 parts of talc (Maruo calcium Ltd., LMR # 200) 100 parts toluene / methyl ethyl ketone (weight ratio 1/1) coated for 400 parts of the dye-receiving layer Liquid 1; vinyl chloride / vinyl acetate copolymer (# 1000D, manufactured by Denki Kagaku Kogyo) 100 parts Amino-modified silicone (X-22-349, manufactured by Shin-Etsu Chemical) 3 parts Epoxy-modified silicone (KF-393, Shin-Etsu Chemical) 3 parts Methyl ethyl ketone / toluene (weight ratio 1/1) 500 parts

Examples and Comparative Examples Using the above materials, thermal transfer image-receiving sheets of the present invention and comparative examples were obtained according to the specifications shown in Table 1 below. The coating conditions for each layer are as follows. Bubble layer: The coating liquid for the bubble layer is applied to one surface of the above substrate using a bar coater after drying so that the coating amount is 15 g / m ² , and then heated and dried in a hot air drier at 120 ° C. for 1 minute. And foamed. Intermediate layer: The coating liquid for the intermediate layer was applied on one surface or the foamed layer of the above-mentioned base material using a bar coater so as to have an application amount after each drying described below, and then dried with a hot air dryer. Dye receiving layer: The receiving layer coating solution was dried on a middle layer using a bar coater so as to have a coating amount of 3 g / m ² , and then dried with a hot air dryer.

[0029]

[Table 1] *: After coating the foam layer, the mixture was heated and foamed at 120 ° C. for 1 minute in a hot air drier. The Lab value of the surface of the receiving layer of each of the thermal transfer image-receiving sheets was measured with a colorimeter Minolta CR-221 and JIS
The specular gloss at 45 degrees of Z8741 was measured with a digital variable-angle gloss meter VG-1D manufactured by Nippon Denshoku Co., Ltd., and was visually observed to obtain the results shown in Table 2 below.

[0030]

[Table 2]

On the other hand, an ink for a dye layer having the following composition was prepared and applied to a 6 μm-thick polyethylene terephthalate film whose back surface was heat-treated at a dry coating amount of 1.0 g / m ^2.
After coating and drying with a wire bar, a few drops of silicone oil (X-41.403A, manufactured by Shin-Etsu Silicone) are dropped on the back with a dropper, then spread over the entire surface and coated on the back to obtain a thermal transfer film. Was. Ink composition for dye layer : Disperse dye (Kayaset Blue 714, manufactured by Nippon Kayaku) 4.0 parts Ethyl hydroxycellulose (manufactured by Hercules) 5.0 parts Methyl ethyl ketone / toluene (weight ratio 1/1) 80.0 parts Dioxane 10.0 parts

The thermal transfer film was superimposed on the surface of the receiving layer of the thermal transfer image-receiving sheet of the present invention and the comparative example, and an output of 0.2 W / dot and a pulse width of 12 using a thermal head.
msec. When printing was performed under the conditions of a dot width of 6 dots / mm to form a cyan image, all of the images were good with no omission or uneven color.

[0033]

According to the present invention as described above, by adding titanium oxide particles and talc particles to the intermediate layer of the thermal transfer image-receiving sheet, the hue of the dye-receiving layer can be reduced without lowering the original function of the dye-receiving layer. It is possible to provide a plain paper-like thermal transfer image receiving sheet on which high-density and high-resolution images can be formed. That is, since the titanium oxide particles and the talc particles do not exist in the dye receiving layer, the original performance of the dye receiving layer does not decrease. The yellowing of the base sheet is concealed by the high concealing property of titanium oxide, and a moderate matte feeling is given by the talc particles,
In a more preferred embodiment, the addition of a fluorescent whitening agent can eliminate the yellowishness of the dye receiving layer itself and increase the whiteness.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-270147 (JP, A) JP-A-5-58059 (JP, A) JP-A-5-169848 (JP, A) JP-A-5-169848 318940 (JP, A) JP-A-3-153390 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41M 5/38-5/40

Claims (4)

(57) [Claims] An air bubble is present on at least one surface of a substrate sheet.
In the thermal transfer image-receiving sheet obtained by sequentially laminating a layer containing the intermediate layer and the dye receiving layer, the intermediate layer is observed containing a titanium oxide particle and talc particles, the titanium oxide particles and talc particles
The weight ratio is 10/90 to 90/10, and the total weight of both
The amount is 10 to 5 per 100 parts by weight of the resin forming the intermediate layer.
A thermal transfer image-receiving sheet characterized by being 00 parts by weight . 2. The thermal transfer image-receiving sheet according to claim 1, wherein the intermediate layer contains 0.01 to 10 parts by weight of a fluorescent whitening agent per 100 parts by weight of the resin of the intermediate layer. 3. The base sheet is made of high quality paper, kraft paper, thermal transfer paper, lightly coated paper, lightweight coated paper, coated paper, art paper,
The thermal transfer image-receiving sheet according to claim 1, which is a paper base mainly composed of natural pulp such as cast-coated paper. 4. The thermal transfer image-receiving sheet according to claim 1 , wherein the bubbles in the bubble-containing layer are made of a microcapsule-type foaming agent.