JPH06115272A - Heat transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To provide a heat transfer image receiving sheet in which a crack of a receptive layer can be prevented even if the layer is deformed due to temperature, humidity change, folding. CONSTITUTION:A heat transfer image receiving sheet comprises a base material sheet 1 and a dye receiving layer 2 formed on a surface of the sheet, wherein the sheet 1 is pulp paper having 150mum or less and the layer 2 contains resin having a tensile strength of 200kg/cm<2> or more.

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 a thermal transfer image-receiving sheet which is free from cracks, can be easily subjected to bending and filing, and has a feeling of plain paper.

[0002]

2. Description of the Related Art Conventionally, various thermal transfer methods have been known, and among them, some use a sublimable dye as a recording agent. There has been proposed a method for forming various full-color images on a thermal transfer image-receiving sheet that can be dyed with a sublimable dye, for example, a dye resin layer formed 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 full-color image of an original is reproduced by multicolored dots of three or four colors by heating for an extremely short time. 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 and gradation of intermediate colors, and It is possible to form a high quality image which is similar to the image obtained by offset printing or gravure printing and which is comparable to a full color photographic image.

[0004]

Problems to be Solved by the Invention As the base material of the thermal transfer image-receiving sheet used in the sublimation type thermal transfer system as described above, a laminated sheet of a plastic sheet and paper, a synthetic paper, etc. are used. In order to extend the use of the sublimation type thermal transfer system to general offices, it is required to use plain paper such as coated paper and cast coated paper PPC paper as the base sheet of the image receiving sheet. When such a general office paper is used as the base sheet, the pulp paper has a poor cushioning property, so that a cushioning intermediate layer between the base sheet and the receiving layer has a glass transition temperature of -50 to.
A resin having a relatively low temperature of 20 ° C. is often provided, and the amount of resin applied to the intermediate layer is large. On the other hand, as the resin for the receiving layer, a resin having a relatively high glass transition temperature of 30 to 80 ° C. is used to prevent fusion of the dye film and the receiving layer due to heat during printing. As described above, since the two layers having different thermal properties have different softness at room temperature, the intermediate layer provided with the resin having a relatively low glass transition temperature with respect to temperature change easily deforms, and The receiving layer deforms in a dragged manner. This deformation causes a problem that the receiving layer is cracked.

Further, when pulp paper is used as the base sheet of the thermal transfer image receiving sheet, the receiving layer is deformed due to curling of the paper due to changes in humidity. Further, during filing and bending, the receiving layer is also deformed by mechanical force.
In order to prevent cracks from occurring due to these deformations, there is a method of increasing the coating thickness of the receiving layer.In this case, one side of the sheet is a resin film and the other side is a pulp fiber There is a problem that the occurrence of curling due to the increase in the amount becomes large. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and provide a plain paper-like heat transfer image-receiving sheet that does not cause cracks.

[0006]

The above object can be achieved by the present invention described below. That is, the present invention comprises a base sheet and a dye receiving layer formed on the surface of the base sheet, wherein the base sheet is a pulp paper of 150 μm or less, and the resin of the dye receiving layer has a tensile strength of 200 Kg / cm ² A thermal transfer image-receiving sheet characterized by using the above resin.

[0007]

In the present invention, as the resin for the dye dyeing layer,
By using a resin having a tensile strength of 200 Kg / cm ² or more, even if the receiving layer provided on the base sheet is deformed due to temperature and humidity changes or bending due to the elasticity of the resin, the receiving layer is cracked. It is possible to prevent the occurrence of.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail with reference to preferred embodiments. The thermal transfer image-receiving sheet of the present invention is used in combination with a thermal transfer sheet having a transfer layer containing a thermally sublimable dye. As shown in FIGS. 1 and 2, the thermal transfer image-receiving sheet of the present invention uses pulp paper of 150 μm or less as the base material sheet 1 as a support, and dyes from the transfer sheet are dyed on the pulp paper. And a cushioning intermediate layer 3 between the base sheet 1 and the image receiving layer 2, if necessary.
Is formed.

The pulp paper base material used in the present invention includes:
Various types of paper, for example, high-quality paper, art paper, coated paper, cast coated paper, thermal transfer paper, Kent paper, etc. are used, and a thickness of about 60 to 150 μm is preferable in order to give a plain paper-like texture. When the thickness of the pulp paper base material is 60 μm or less, there are problems in strength and transportability in the printer, and when the thickness is 150 μm or more, it is not preferable in terms of weight and cost.

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. In the present invention, a resin having a tensile strength of 200 Kg / cm ² or more is used as the binder resin for forming the dye receiving layer. For example, polyester resin, polyurethane resin, butyral resin, polyolefin resin such as polypropylene, polyvinyl chloride, vinyl chloride / vinyl acetate copolymer resin, ionomer, cellulose resin such as cellulose diacetate, polycarbonate, etc. These may be used alone or as a mixture. Particularly preferred are polyester resins and vinyl chloride / vinyl acetate copolymer resins. The tensile strength of the resin in the present invention is based on the measuring method described in JIS-K-7113. Tensile strength of 200 kg / cm ²
If it is lower, cracks easily occur on the resin surface due to temperature and humidity changes, bending, etc., leading to deterioration in image quality. When the glass transition point of the resin is lower than 30 ° C., thermal fusion between the dye film and the receiving layer occurs during high energy printing, which causes jamming in the printer. On the other hand, when the glass transition point exceeds 80 ° C., the sensitivity is lowered and a sufficient image density cannot be obtained.

These resins are dissolved in an organic solvent such as toluene or methyl ethyl ketone and, for example, a coating solution containing necessary additives such as a release agent, an antioxidant, an ultraviolet absorber and the like is prepared by a gravure reverse coating method or the like. Is applied and dried on the above-mentioned base material to form a receiving layer.

In the present invention, the dye receiving layer may be formed by a transfer method. When a pulp paper substrate is used as the sheet, the curl balance of the paper becomes unstable due to the drying at the time of coating the dye receiving layer in the above coating method, but the transfer method does not cause such a problem. The transfer method is, for example, forming the dye receiving layer on a film surface having good releasability such as a polyester film, further providing an appropriate pressure-sensitive adhesive layer or adhesive layer on the surface thereof, and applying a viscous / adhesive layer to the pulp. This is a method in which the surface of the paper substrate is opposed to the surface of the paper substrate, which is laminated with a laminator or the like, and then the polyester film is peeled. or,
When forming the intermediate layer, the intermediate layer may be previously formed on the surface of the pulp paper, or may be provided between the receiving layer and the adhesive layer.

The dye receiving layer preferably contains a releasing agent in order to impart a good releasing property to the thermal transfer sheet. Preferred releasing agents include silicone compounds, for example, liquid or solid silicone polymers, silicone grease, silicone oil, phosphate ester surfactants, and fluorine surfactants, with silicone compounds being particularly preferred. Reactive silicone oil is preferred. As the above silicone oil, modified silicone oil such as epoxy modified, alkyl modified, amino modified, carboxyl modified, alcohol modified, fluorine modified, alkylaralkyl polyether modified, epoxy / polyether modified, polyether modified is desirable. These reactive silicones react with each other or with the receiving layer resin. As the release agent, one type or two or more types are used. Further, the amount of the release agent added is the binder resin 10
1 to 20 parts by weight is preferable with respect to 0 parts by weight. If the addition amount range is not satisfied, problems such as fusion of the thermal transfer sheet and the dye receiving layer or reduction of printing sensitivity may occur. The thickness of the dye receiving layer formed as described above is
It is preferably about 1 to 10 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 a resin dispersion.

Further, in the present invention, as shown in FIG. 3, for the purpose of improving the transportability of the image receiving sheet in the printer, the surface opposite to the dye receiving layer is made of, for example, acrylic resin or acrylic silicone resin. A resin having excellent smoothness or suitable lubricating particles is added to the resin, and, for example, 1 to 5 g /
It is also preferable to form the slip layer 4 having a thickness of about m ² . The thermal transfer sheet used when performing thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is one in which a sublimable dye layer is provided on paper or a polyester film, and any conventionally known thermal transfer sheet is It can be used as it is in the invention. Further, as the means for applying the thermal energy at the time of thermal transfer, any conventionally known applying means can be used, and for example, the recording time is controlled by a recording device such as a thermal printer (for example, Hitachi Ltd., video printer VY-100). The intended purpose can be sufficiently achieved by applying thermal energy of about 5 to 100 mJ / mm ² .

Further, in the image-receiving sheet of the present invention, a cushioning intermediate layer is provided between the base sheet and the dye-receiving layer, if necessary, so that there is little noise during printing and an image corresponding to image information can be reproduced with good reproducibility. Can be transcribed and recorded.

Examples of the resin having a glass transition point of −50 to 20 ° C. for forming the intermediate layer include acrylic resin, urethane resin, ethylene-vinyl acetate copolymer and the like.
When the glass transition point is lower than −50 ° C., the resin protrudes from the end surface of the image receiving sheet, resulting in poor processability such as cutting. If the glass transition point exceeds 20 ° C., sufficient cushioning properties cannot be obtained and a smooth and clear image cannot be obtained.

As the method of forming the intermediate layer, for example, the intermediate layer is formed by coating and drying on the base material sheet by a forming means such as a gravure printing method, a screen printing method and a gravure reverse coating method. The coating amount of the intermediate layer thus formed is preferably 5 to 40 g / m ² . When the receiving layer is formed by the transfer method, it is formed between the receiving layer and the adhesive layer.

In a preferred embodiment of the present invention, the above intermediate layer contains a white pigment, a filler and / or a fluorescent whitening agent. As for the method of incorporating the white pigment and the like, the white pigment may be incorporated in the coating liquid used for forming the intermediate layer. Two intermediate layers may be provided and only one may contain a white pigment. The white pigment or filler has the purpose of improving the whiteness and hiding power of the intermediate layer and preventing the background color of the base sheet from adversely affecting the image. Examples of such white pigments or fillers include white pigments such as titanium oxide, kaolin clay, calcium carbonate, and fine powder silica. The addition amount of these white pigments varies depending on the type of pigment used, but is generally about 1 to 500 parts by weight per 100 parts by weight of the intermediate layer forming resin.

Further, the fluorescent whitening agent eliminates the yellowing of the resin in the intermediate layer and improves the whiteness, and includes, for example, stilbene type, diaminodiphenyl type, oxazole type, imidazole type, thiazole type, Known fluorescent whitening agents such as coumarin type, naphthalimide type and thiophine type are used. These fluorescent whitening agents are dissolved in the resin liquid for the intermediate layer and have a sufficient effect at an extremely low concentration, for example, 0.01 to 5% by weight.

[0020]

EXAMPLES Next, the present invention will be described more specifically with reference to Examples and Comparative Examples. In the text, parts and% are based on weight unless otherwise specified. Example 1 A receptive layer coating solution having the following composition was applied to the surface of a 12 μm-thick polyester film (trade name “Lumirror”, manufactured by Toray) at a rate of 3.0 g / m ² when dried by a bar coater. Then, after drying with a drier, it is dried in an oven at 100 ° C. for 30 minutes to form a dye receiving layer, and the following adhesive solution is similarly coated on the receiving layer at a rate of 15 g / m ² and dried. Then, an adhesive layer was formed to obtain a receptor layer transfer film used in the present invention. The above receiving layer transfer film was placed on a thermal transfer paper (TRW-1, Jujo Paper Co., Ltd.), both were passed through a laminate to be bonded, and then the substrate film was peeled off to obtain a thermal transfer image-receiving sheet of the present invention. The tensile strength is according to the method of JIS-K-7113. Receptor layer coating liquid composition ; vinyl chloride / vinyl acetate copolymer (1000 L, manufactured by Denki Kagaku Kogyo, tensile strength 200 Kg / cm ² ) 100 parts Epoxy modified silicone (KF-393, manufactured by Shin-Etsu Chemical Co., Ltd.) 5 parts amino modified Silicone (KF-343, manufactured by Shin-Etsu Chemical Co., Ltd.) 5 parts Methyl ethyl ketone / toluene (weight ratio (1/1)) 500 parts Adhesive layer-like coating liquid composition ; Emulsion-based adhesive (E-1000, manufactured by Soken Chemical Co., Ltd.) 100 50 parts of water

Examples 2 to 5 The thermal transfer image-receiving sheet of the present invention was obtained in the same manner as in Example 1 except that the resin for receiving layer shown in Table 1 below was used as the resin for receiving layer.

Example 6 The surface of PET having a thickness of 100 μm was coated with the coating solution for the receptor layer having the composition of Example 1 by a bar coater at a rate of 3 g / m ² when dried, and dried with a drier to give 100 It was dried in an oven at ℃ for 30 minutes to form a dye receiving layer to obtain a thermal transfer image-receiving sheet of the present invention.

Example 7 On a surface of PET having a thickness of 100 μm, an intermediate layer coating solution having the following composition was applied by a bar coater at a rate of 5 g / m ² when dried, dried by a drier, and further coated thereon. Was coated with a coating solution for the receptor layer having the composition of Example 1 by a bar coater at a rate of 3 g / m ² when dried, dried with a dryer, and then dried in an oven at 100 ° C. for 30 minutes to form a dye receptor layer. Thus, the thermal transfer image-receiving sheet of the present invention was obtained. Composition of coating liquid for intermediate layer : Urethane resin (NL-2450, Mitsui Toatsu Chemicals) 100 parts Toluene / methyl ethyl ketone (weight ratio (1/1)) 400 parts Dimethylformamide 50 parts Titanium oxide (TCA888, Tochem Products) 200 parts

Example 8 A slip layer having the following composition was applied on the back surface of the image-receiving paper of Example 1 by a bar coater at a rate of 1 g / m ² when dried, dried by a dryer and then ovened at 100 ° C. Thirty
After drying for a minute, a dye receiving layer was formed to obtain a thermal transfer image receiving sheet of the present invention. Slip layer coating liquid composition : Acrylic resin (Dianal BR-85, Mitsubishi Rayon) 100 parts Teflon filler (Lubron L-5, Daikin) 30 parts Toluene / methyl ethyl ketone (weight ratio (1/1)) 400 parts

Comparative Examples 1 and 2 The thermal transfer image-receiving sheet of Comparative Example was obtained in the same manner as in Example 1 except that the resin for receiving layer shown in Table 1 below was used as the resin for receiving layer in Example 1.

[0027]

[Table 1]

Using the image-receiving sheets of the present invention and comparative examples obtained above, solid black printing was performed by a video printer (CP-11, manufactured by Mitsubishi Electric Corporation), and a cylinder having a diameter of 200 mm was formed so that the printing surface was on the inside. Wrap it in the refrigerator (5 ℃, 40%
When the mixture was left for 24 hours in RH) and examined for crack inclusion, the results shown in Table 2 below were obtained.

[0029]

[Table 2]

[0030]

As described above, according to the present invention, by using a resin having a tensile strength of 200 Kg / cm ² or more as the resin for the receiving layer, it is possible to prevent the receiving layer from undergoing temperature / humidity fluctuations or mechanical damage. It is possible to prevent cracking.

[Brief description of drawings]

1 to 3 are sectional views showing the structure of the thermal transfer image-receiving sheet of the present invention. (Explanation of reference numerals) 1 ・ ・ ・ ・ ・ ・ ・ ・ ・ Base sheet 2 ・ ・ ・ ・ Receiving layer 3 ・ ・ ・ Intermediate Layer 4 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Slip layer

[Procedure amendment]

[Submission date] March 26, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a basic sectional view of a thermal transfer image receiving sheet.

2 is a thermal transfer image-receiving sheet provided with an intermediate layer of Example 7. FIG.

FIG. 3 is a thermal transfer image receiving sheet provided with a slip layer of Example 8.

[Explanation of symbols] 1 base sheet 2 receiving layer 3 intermediate layer 4 slip layer

Claims (2)

[Claims] 1. A thermal transfer image-receiving sheet comprising a base sheet and a dye receiving layer formed on the surface of the base sheet, wherein the base sheet is a pulp paper having a size of 150 μm or less, and the resin for the dye receiving layer has a tensile strength. A thermal transfer image-receiving sheet characterized by using a resin of 200 kg / cm ² or more. 2. The thermal transfer image-receiving sheet according to claim 1, comprising a base sheet and a dye receiving layer formed on the surface of the base sheet with an intermediate layer interposed therebetween.