JPH05246151A - Heat transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To provide a heat transfer image receiving sheet which provides a clear image with an enough density and exhibits excellent durabilities, especially excellent light-resistance, fingerprint-resistance, etc., of a formed image in a method for heat transfer using a sublimation dye. CONSTITUTION:A heat transfer image receiving sheet characterized by a sheet wherein a polyvinyl acetal resin contg. carboxyl groups is incorporated in a dye accepting layer in the heat transfer image receiving sheet wherein the dye accepting layer is formed on at least one face of a base material sheet.

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, it has excellent color density, vividness and various fastnesses, particularly excellent durability such as light resistance, fingerprint resistance, plasticizer resistance, heat resistance and the like. An object is to provide a thermal transfer image-receiving sheet capable of forming a recorded image.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods are known. Among them, a sublimable dye is used as a recording agent, and a sublimable dye is used as a thermal transfer sheet by supporting it on a base material sheet such as polyester film. Transferable material that can be dyed, for example,
There has been proposed a method of forming various full-color images on an image receiving sheet having a dye receiving layer formed on paper, a plastic film or the like. In this case, the thermal head of the printer is used as the heating means, and a large number of three-color or four-color dots are transferred to the image-receiving sheet by heating for an extremely short time, and the full-color image of the original is formed by the multi-color dots. It is to be reproduced. The image formed in this way is extremely clear because the coloring material used is a dye and has excellent transparency, so the resulting image has excellent reproducibility of intermediate colors and gradation, and It is possible to form a high quality image which is similar to the image obtained by the offset printing or gravure printing and which is comparable to the full color photographic image.

[0003]

In order to effectively carry out the above-mentioned thermal transfer method, not only the structure of the thermal transfer sheet but also the structure of the image receiving sheet for forming an image are important. As a conventional technique of the thermal transfer image receiving sheet, for example, JP-A-57-169370 and 57-207 are known.
250, 60-25793, etc., polyester resins, vinyl resins such as polyvinyl chloride resins, polycarbonate resins, polyvinyl butyral resins, acrylic resins, cellulose resins, olefin resins, polystyrene resins. A resin in which a dye receiving layer is formed by using the above is disclosed. In the thermal transfer image-receiving sheet as described above, it is known that the dye-dyeing property of the dye-receiving layer and the various durability and storage stability of the image formed thereon are greatly changed depending on the resin forming the dye-receiving layer. There is. As a means for improving the dyeability of the dye to be transferred, a dye receiving layer is formed from a resin having good dyeability,
A plasticizer in the dye-receiving layer may be included to improve the diffusibility of the dye during thermal transfer.However, in the dye-receiving layer made of a resin having good dye-dyeing property, it is formed. Further, the image bleeds during storage, the image storability is inferior, and the fixing property of the dye is inferior. Therefore, there is a problem that the dye bleeds out to the surface and easily contaminates other articles that come into contact with the surface.

As a method for solving the above-mentioned problems of storability, stainability and the like, a resin in which the dyed dye does not easily migrate in the dye receiving layer may be selected. In this case, the dyeing of the dye is performed. There is a problem that the image is inferior and a high-density and high-definition image cannot be formed. Further, as another big problem, when the dyed dye has light resistance and when the image portion is touched with a hand, the image is discolored due to the influence of sweat or sebum transferred to the image surface, and the dye receiving layer itself is swelled or swelled. There is a problem of cracking, that is, a problem of fingerprint resistance, and a problem of migration of a dye when contacted with a substance containing a plasticizer such as an eraser or a soft vinyl chloride resin product, that is, a problem of plasticizer resistance. Examples of the resin that forms the dye receiving layer having excellent light resistance include polyvinyl acetal resins. Examples thereof include JP-A-57-207250, JP-A-60-25793, and JP-A-61-1.
Various polyvinyl acetal resins are disclosed in JP 1293, JP 3-65391 A, JP 3-162989 A and the like, but polyvinyl acetals such as polyvinyl butyral and polyvinyl acetoacetal disclosed therein are disclosed. In the case of resin based resins, there is a problem that the dye receiving layer to be formed has poor fingerprint resistance, plasticizer resistance, etc., and further, dyeing property of dye is poor, and it is not possible to form a high-concentration and high-definition image. .. Therefore, the object of the present invention is to provide a clear image with sufficient density in a thermal transfer method using a sublimable dye, and the formed image has excellent various fastnesses, particularly excellent light resistance and fingerprint resistance, It is an object of the present invention to provide a thermal transfer image-receiving sheet that exhibits plasticizer resistance and the like.

[0005]

The above object can be achieved by the present invention described below. That is, the present invention is a thermal transfer image-receiving sheet in which a dye receiving layer is formed on at least one surface of a base sheet, wherein the dye receiving layer contains a polyvinyl acetal resin containing a carboxyl group. It is a thermal transfer image-receiving sheet.

[0006]

[Function] By forming the dye-receiving layer using a carboxyl group-containing polyvinyl acetal resin, in a thermal transfer method using a sublimable dye, a clear image with sufficient density is obtained, and the formed image is It is possible to provide a thermal transfer image-receiving sheet having excellent various fastnesses, particularly excellent light resistance, fingerprint resistance, plasticizer resistance and the like.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail with reference to the following preferred embodiments. The thermal transfer image-receiving sheet of the present invention comprises a dye receiving layer provided on at least one surface of a substrate sheet. The base sheet used in the present invention,
Synthetic paper (polyolefin-based, polystyrene-based, etc.), high-quality paper, art paper, coated paper, cast-coated paper, wallpaper, backing paper, synthetic resin or emulsion-impregnated paper, synthetic rubber latex-impregnated paper, synthetic resin internal-added paper, paperboard, etc. Films or sheets of various plastics such as, cellulose fiber paper, polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, polymethacrylate, polycarbonate, etc. can be used, and white pigments and fillers are added to these synthetic resins. A filmy white opaque film or a foamed foamed sheet can be used without any particular limitation. Further, a laminated body made of any combination of the above-mentioned substrate sheets can also be used. As an example of a typical laminated body, a synthetic paper of cellulose fiber paper and synthetic paper or cellulose fiber paper and plastic film or sheet can be mentioned. The thickness of these base material sheets may be arbitrary, for example, 10 to 30.
Generally, the thickness is about 0 μm. The substrate sheet as described above is preferably subjected to a primer treatment or a corona discharge treatment on the surface when the adhesion to the dye receiving layer formed on the surface is poor.

The dye receiving layer formed on the surface of the base sheet is for receiving the sublimable dye transferred from the thermal transfer sheet and maintaining the formed image. The polyvinyl acetal resin used for forming the dye receiving layer in the present invention can be obtained by acetalizing polyvinyl alcohol with an aldehyde by a known method. As the aldehyde used, for example,
Formalin, alkyl aldehyde, benzaldehyde,
Examples thereof include naphthaldehydes, and examples of alkylaldehydes other than formalin include linear or branched alkyl groups and halogenated alkylaldehydes. Examples of the aromatic aldehyde include an alkyl group, an alkoxy group on a benzene ring or a naphthalene ring, a benzaldehyde which may be substituted with a halogen atom, a naphthaldehyde, etc., and an arylalkyl aldehyde such as benzyl aldehyde may also be used. ..

The method of introducing a carboxyl group into the polyvinyl acetal resin is not particularly limited, but examples thereof include maleic acid, maleic acid half ester, acrylic acid,
A method of copolymerizing a carboxyl group-containing addition-polymerizable monomer such as methacrylic acid or itaconic acid during the polymerization of vinyl acetate, or a carboxyl group by reacting with a fatty acid vinyl ester and an acid used as a catalyst during the acetalization reaction. Completely or partially saponification or alcoholysis of a copolymer with a monomer having a side chain that is changed to ## STR1 ## [eg, acrylamide (see Japanese Patent Publication No. 46-7605), methacrylamide, etc.]. Carboxy modified polyvinyl alcohol can be obtained also by carrying out, and it can also be obtained by making it acetal.
Further, a method of acetalizing polyvinyl alcohol with an aldehyde containing a carboxyl group can be mentioned. A particularly preferred method is the former method in which the carboxyl group is pendant to the main chain. It is particularly suitable for achieving the object of the present invention that these monomers or aldehydes introducing a carboxyl group account for 0.5 to 20% by weight of the obtained polyvinyl acetal resin. The degree of acetalization of the polyvinyl acetal resin is preferably in the range of 50 to 95% by weight of the hydroxyl groups of polyvinyl alcohol. Polyvinyl alcohol used as a raw material preferably has a degree of polymerization of 200 to 3,500, and may partially contain unsaponified acetyl groups or fatty acid ester groups.

In the present invention, the above-mentioned polyvinyl acetal resin containing a carboxyl group can be used alone or as a mixture, and other thermoplastic resins, for example, polyolefin resin such as polypropylene, polyvinyl chloride, polyvinylidene chloride. Halogenated polymers such as, polyvinyl acetate, polyacrylic esters, polyvinyl polymers such as polyvinyl acetal, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polystyrene resins, polyamide resins, olefins such as ethylene and propylene, and other A copolymer resin with a vinyl monomer, an ionomer, a cellulose resin such as cellulose diacetate, a polycarbonate, or the like can be used in combination.

The thermal transfer image-receiving sheet of the present invention comprises a carboxyl group-containing polyvinyl acetal resin as described above and other necessary additives such as a releasing agent, a cross-linking agent and a curing agent on at least one surface of the above-mentioned substrate sheet. A dispersion prepared by dissolving an agent, a catalyst, a heat release agent, an ultraviolet absorber, an antioxidant, a light stabilizer, etc., in an appropriate organic solvent or dispersing it in an organic solvent or water, for example, gravure. It can be obtained by applying and drying by a forming means such as a printing method, a screen printing method or a reverse roll coating method using a gravure plate to form a dye receiving layer. In forming the dye receiving layer, pigments or fillers such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate and finely powdered silica are used for the purpose of improving the whiteness of the dye receiving layer and further enhancing the sharpness of the transferred image. Agents can be added. The dye-receptive layer formed as described above may have any thickness, but generally has a thickness of 1 to 50 μm. Further, such a dye receiving layer is preferably a continuous coating, but it may be formed as a discontinuous coating by using a resin emulsion or resin dispersion.

Further, the thermal transfer image-receiving sheet of the present invention can be applied to various applications such as cards capable of thermal transfer recording and transmission type document preparation sheets by appropriately selecting a substrate sheet. Further, the thermal transfer image-receiving sheet of the present invention can be provided with a cushion layer between the substrate sheet and the dye receiving layer, if necessary, and by providing such a cushion layer, there is less noise during printing and the image information is displayed. Corresponding images can be transferred and recorded with good reproducibility. The thermal transfer sheet used when performing thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is a paper or polyester film provided with a dye layer containing a sublimable dye, and a conventionally known thermal transfer sheet is Both can be used as they are in the present invention. Further, as the means for applying the heat energy during the thermal transfer, any conventionally known applying means can be used. For example, the recording time is controlled by a recording device such as a thermal printer (for example, a video printer VY-100 manufactured by Hitachi, Ltd.). By doing, 5-100mJ
The intended purpose can be sufficiently achieved by applying thermal energy of about / mm ² .

[0013]

EXAMPLES The present invention will be described in more detail with reference to Synthesis Examples, Examples and Comparative Examples. In the text, “part” or “%” is based on weight unless otherwise specified. Synthesis Example (Production of Carboxy Modified Polyvinyl Acetal Resin) 400 parts of methanol and 5 parts of 35% hydrochloric acid were charged into a reactor equipped with a stirrer, a reflux condenser and a thermometer, and then acrylamide modified PVA (average polymerization degree 1, 730, residual acetic acid groups (4.5 mol%, acrylamide content 7.5 mol%) and 85 parts were added with stirring. Then, 60 parts of acetaldehyde was added thereto, and the mixture was reacted at a temperature of 60 ° C. for 6 hours to obtain a methanol solution of carboxy-modified polyvinyl acetal. This solution was cooled, neutralized with ethylene oxide, water was added while stirring to carry out a precipitation operation, washed with water and dried to obtain a white powdery carboxy-modified polyvinyl acetal resin. The average composition of the obtained resin is 77.9% by weight of the acetal portion, 12.5% by weight of the vinyl alcohol portion and 3.9% by weight of the vinyl acetate portion.
And the carboxyl group portion was 5.7% by weight. (Note) Composition analysis method The vinyl alcohol portion and vinyl acetate portion of the carboxy-modified polyvinyl acetal resin are measured according to JIS.
It carried out according to K-6728. The content of the carboxyl group portion was obtained from a value obtained by quantitating the sodium of the carboxyl group using an atomic absorption spectrophotometer. Examples 1 to 10 and Comparative Example 1 As a base sheet, synthetic paper (manufactured by Oji Yuka, thickness 110 μm)
m), a coating solution having the following composition was applied to one surface of the m) by a wire bar at a rate of 5.0 g / m ² when dried, and dried and cured to obtain the thermal transfer image-receiving sheets of the present invention and comparative examples. Obtained. Composition of coating liquid: Resin of Table 1 15.0 parts Catalyst-curable silicone oil (X-621212, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.5 parts Platinum-based catalyst (Cat PL50T, manufactured by Shin-Etsu Chemical Co., Ltd.) 0.1 part Methyl ethyl ketone / toluene (weight ratio 1/1) 83.5 parts

[0014]

[Table 1]

On the other hand, an ink for forming a dye carrying layer having the following composition
The composition was prepared and the backside was heat-treated to a thickness of 6 μm.
The dry coating amount of polyethylene terephthalate film
1.0 g / m^TwoAnd apply with a wire bar
It was dried to obtain a heat transfer sheet. Ink composition; Indoaniline dye having the following structural formula 1.0 part Polyvinyl butyral resin (S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 10.0 parts Methyl ethyl ketone / toluene (weight ratio 1/1) 90.0 parts

[Chemical 1] The thermal transfer sheet and the thermal transfer image-receiving sheet of the present invention and the comparative example are superposed with their dye layers and dye receiving surfaces facing each other, and a head applied voltage of 11.0 V and a pulse width of 16 msec from the back surface of the thermal transfer sheet. ． Recording was performed with a thermal head under the condition of a dot density of 6 dots / line, and the results shown in Table 2 below were obtained. In addition, the evaluation method of each performance shown in Table 2 was performed as follows.

(1) Light fastness test method The obtained image was measured with a xenon fade odometer (Ci-35A, manufactured by Atlas Co.) at 100 KJ / m ² (420).
(a cumulative light amount of nm), and the change in the optical density before and after irradiation is measured by an optical densitometer (Macbeth RD-918).
The residual ratio of optical density was calculated by the following formula. Residual rate (%) = {[optical density after irradiation] / [optical density before irradiation]} × 100 ◎; residual rate is 90% or higher ○: residual rate is 80% or higher and lower than 90% Δ; residual rate is 70 % Or more and less than 80% x; residual rate is less than 70% (2) Fingerprint resistance evaluation method After fingerprints were imprinted on the surface of the printed matter and left at room temperature for 5 days,
The degree of discoloration and density change of the fingerprint imprinted portion was visually evaluated. A: Almost no difference between the fingerprint imprinted part and the non-imprinted part was recognized. B: Discoloration or change in density was observed. C: The imprinted part of the fingerprint was blank, and the fingerprint shape was clearly recognized. D: White spots occurred around the fingerprint imprinted portion, and at the same time, dye aggregation was observed. (3) Evaluation method of plasticizer resistance The same portion of the printed material surface was lightly rubbed with a commercially available plastic eraser three times, and the degree of change in density was visually determined. A: Almost no change in concentration was observed. B: A change in concentration was observed. C: The density changed greatly, and white spots were seen from the low density area to the medium density area.

[0017]

[Table 2]

[0018]

[Effects] According to the present invention as described above, by forming a dye receiving layer using a carboxyl group-containing polyvinyl acetal resin, a clear image with sufficient density can be obtained in a thermal transfer method using a sublimable dye. Further, it is possible to provide a thermal transfer image-receiving sheet which gives an image having excellent fastness, particularly excellent light resistance, fingerprint resistance, plasticizer resistance and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsushi Hasegawa 1-1-1, Tanikaga-cho, Shinjuku-ku, Tokyo Inside Dai Nippon Printing Co., Ltd.

Claims (3)

[Claims] 1. A thermal transfer image-receiving sheet comprising a base sheet and a dye receiving layer formed on at least one surface of the base sheet, wherein the dye receiving layer contains a polyvinyl acetal resin containing a carboxyl group. Image receiving sheet. 2. The thermal transfer image-receiving sheet according to claim 1, wherein the component constituting the carboxyl group is a carboxyl group-containing addition polymerizable monomer. 3. The content of the monomer unit containing a carboxyl group is 0.5 to 20 of that of the polyvinyl acetal resin.
The thermal transfer image-receiving sheet according to claim 1, wherein the thermal transfer image-receiving sheet has a weight percentage.