JP2914982B2 - Thermal transfer image receiving sheet and thermal transfer method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal transfer image-receiving sheet and a thermal transfer method.
More specifically, an object of the present invention is to provide a thermal transfer image-receiving sheet and a thermal transfer method capable of forming a recorded image having excellent color density, sharpness and various fastnesses.

(Prior art) Conventionally, various thermal transfer methods are known. Among them, a sublimable dye is used as a recording agent, and the recording agent is supported on a base sheet such as paper to form a thermal transfer sheet. A sublimation transfer method in which a sublimable dye is transferred to a transfer-receiving material by applying thermal energy in a pattern from the surface of a thermal transfer sheet, which is overlaid on a transferable transferable material, for example, a polyester woven cloth or the like, has been performed.

(Problems to be Solved by the Invention) In the above-described sublimation transfer method, in the sublimation printing method in which the material to be transferred is, for example, a woven fabric made of polyester or the like, the heat energy is applied for a relatively long time. As a result, the transfer is achieved with a relatively good dye.

However, due to advances in recording methods, using a thermal head or the like at a high speed, for example, using a transfer material provided with a dye receiving layer on a polyester sheet or paper, and delicate characters and figures on these transfer materials Alternatively, in the case of forming a photographic image, the application of thermal energy is required to be extremely short in seconds or less, and therefore, the sublimable dye and the material to be transferred are not sufficiently heated in such a short time. Therefore, an image having a sufficient density cannot be formed.

Therefore, to cope with such high-speed recording, sublimable dyes having excellent sublimability have been developed. In this case, there is a problem that the dye migrates with time or bleeds on the surface, so that the formed image is disturbed, becomes unclear, or contaminates surrounding articles.

In order to avoid such a problem, when a sublimable dye having a relatively large molecular weight is used, the sublimation speed is inferior in the high-speed recording method as described above, so that an image having a satisfactory density cannot be formed as described above. Met.

Accordingly, an object of the present invention is to provide a clear image having a sufficient density by applying heat energy for an extremely short time as described above in a thermal transfer method using a sublimable dye, and the formed image is excellent. An object of the present invention is to provide a thermal transfer image receiving sheet showing various fastnesses.

(Means for Solving the Problems) The above object is achieved by the present invention described below.

That is, the present invention comprises a substrate sheet and a dye receiving layer formed on at least one surface of the substrate sheet,
The dye receiving layer is made of a copolymer of vinyl chloride and an acrylic acid monomer, wherein the degree of polymerization of the copolymer is 50 to 500, using a sublimation type thermal transfer sheet and a thermal head. A thermal transfer image-receiving sheet for forming an image and a thermal transfer method using the image-receiving sheet.

(Function) By forming the receiving layer of the thermal transfer image-receiving sheet from a copolymer of vinyl chloride and an acrylic acid-based monomer, the bleeding resistance of the received dye is improved even when a relatively low molecular weight dye is used. Thus, an image having excellent clarity, density, storage stability and the like can be formed. Even when a relatively high molecular weight dye is used, the dye receptivity is excellent, so that an image excellent in sharpness, density, storage stability and the like can be formed.

In particular, when a dye having a basic amino group is used as the sublimable dye, the dye is trapped by an acidic group in the receptor layer, so that the bleeding resistance is further improved.

Preferred Embodiment 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 comprises a base sheet and a dye receiving layer provided on at least one surface thereof.

The base sheet used in the present invention includes synthetic paper (polyolefin, polystyrene, etc.), woodfree 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 paper, board paper, cellulose fiber paper, polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, poly Various plastic films or sheets such as methacrylate and polycarbonate can be used and are not particularly limited.

Also, a laminate formed by any combination of the above-mentioned base sheets can be used. Examples of typical laminates include synthetic paper of cellulose fiber paper and synthetic paper or cellulose fiber paper and plastic film or sheet.

The 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 receiving layer is formed from a copolymer of vinyl chloride and an acrylic acid monomer,
It may be formed from a mixture of such a copolymer of vinyl chloride and an acrylic acid-based monomer with another resin. In particular, in the present invention, it has been found that when the degree of polymerization of the copolymer used is 50 to 500, excellent dye receptivity is exhibited.
If the degree of polymerization is less than 50, the coating strength and heat resistance of the formed receiving layer will be insufficient, and will adhere to the thermal transfer sheet at the time of thermal transfer, making smooth thermal transfer impossible. On the other hand, the degree of polymerization is 50
If it exceeds 0, the acceptability of the dye becomes insufficient, which is not preferable.

The copolymer used in the present invention is obtained by copolymerization of vinyl chloride and acrylic acid monomer,
It is also possible to copolymerize small amounts of third monomers, for example up to 10 mol%.

Preferred acrylic acid monomers that can be used include:
For example, (meth) acrylic (the term means both acrylic and methacrylic) acids, their metal salts, (meth)
Acrylic acid methyl, ethyl, propyl, butyl, 2-
Ethylhexyl, hydroxyethyl, cyclohexyl,
Examples thereof include mono-, di- or tri (meth) acrylates of alkyl esters such as n-stearyl, tridecyl and the like, and polyols such as ethylene glycol, diethylene glycol and trimethylolpropane. The use of di- or trimethacrylate can improve the heat resistance of the dye-receiving layer. However, if the amount is too large, the amount of the dye-receiving layer formed in the receiving layer is reduced. . By using (meth) acrylic acid in an amount of up to 10% by mole as a part of the acrylic acid monomer, the acceptability of the sublimable dye and the bleeding resistance are improved.
If the amount is too large, the dye receptivity decreases.

The copolymerization ratio of the vinyl chloride and the acrylic acid monomer is not particularly limited, but a preferable copolymerization ratio is vinyl chloride / acrylic acid monomer = 10/90 to 90/10 (molar ratio).
It is.

The thermal transfer image-receiving sheet of the present invention is obtained by dissolving the above-described copolymer or a mixture thereof with another resin in an appropriate organic solvent or dispersing in an organic solvent or water on at least one surface of the base sheet. The resulting dispersion is applied and dried to form a dye-receiving layer. When a copolymer and another resin are used as a mixture, the content of the copolymer is preferably 5% by weight or more, more preferably 10% by weight or more in the total of both.

In the formation of the receiving layer, pigments and 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 receiving amount and further increasing the sharpness of the transferred image. Can be added.
Further, in order to further enhance the light fastness of the transferred image, an ultraviolet absorber and / or a light stabilizer can be added to the receiving layer.

Such a dye-receiving layer may be of any thickness, but is generally between 30 and 50 μm. Further, such a dye receiving layer is preferably a continuous coating, but may be formed as a discontinuous coating using a resin emulsion or a resin dispersion.

Although the thermal transfer image-receiving sheet of the present invention can basically be used satisfactorily even with the above-described constitution, the dye-receiving layer can contain an inorganic powder for preventing adhesion.
In this way, even if the temperature during thermal transfer is further increased, adhesion between the thermal transfer sheet and the thermal transfer image-receiving sheet can be prevented, and more excellent thermal transfer can be performed. Particularly preferred is finely divided silica.

Further, a resin having good releasability may be added in place of or in combination with the above-mentioned inorganic powder such as silica. A particularly preferred release polymer is a cured product of a silicone compound, for example, a cured product composed of an epoxy-modified silicone oil and an amino-modified silicone oil. Such a release agent preferably accounts for about 0.5 to 30% by weight of the weight of the dye receiving layer.

The thermal transfer sheet used when performing thermal transfer using the thermal transfer image-receiving sheet of the present invention as described above is provided with a dye layer containing a sublimable dye on paper or a polyester film. Any of them can be used as it is in the present invention.

According to the study of the present inventors, it is preferable that the dye used in the thermal transfer sheet is a dye having at least one primary to tertiary amino group, and in particular, indoaniline represented by the following structural formula It has been found that the best image can be formed in the case of a dye of the type, cyanoacetyl type or anthraquinone type.

(R _{1 to} R ₄ in the above formula are a C _{1 to} C ₆ alkyl group, cycloalkyl group or phenyl group, R ₂ may be a hydrogen atom or an alkoxy group, and R ₃ and R ₄ are ring X is a hydrogen atom, a halogen atom, a lower alkyl group,
Represents a substituent such as an alkoxy group or a nitro group. As a means for applying thermal energy at the time of thermal transfer, any conventionally known applying means can be used. For example, a thermal printer (for example, a video printer VY-10 manufactured by Hitachi, Ltd.) can be used.
The intended purpose can be sufficiently achieved by applying a thermal energy of about 5 to 100 mJ / mm ² by controlling the recording time with a recording device such as 0).

(Effects) According to the present invention as described above, by forming the dye receiving layer of the thermal transfer image receiving sheet from a copolymer of vinyl chloride and an acrylic acid-based monomer, a clear image with high density is formed. Has excellent bleed resistance and stain resistance, so even if the image is stored for a long period of time, the sharpness of the image does not decrease, and even if it comes in contact with other articles, it does not stain them. Various problems have been solved.

(Examples) Next, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, parts and% are based on weight unless otherwise specified.

Example An ink composition for forming a dye carrying layer having the following composition was prepared,
A 6 μm-thick polyethylene terephthalate film having a heat-treated back surface was coated and dried so that the dry coating amount was 1.0 g / m ² , to obtain a thermal transfer sheet shown in Table 1 below.

Dye of the above structural formula 3.0 parts Polyvinyl butyral resin 4.5 parts Methyl ethyl ketone 46.25 parts Toluene 46.25 parts However, when the dye mixture was insoluble in the above composition, DMF, dioxane, chloroform or the like was appropriately used as a solvent.

Next, as a base sheet, synthetic paper (Oji Yuka, YUPO FP
G # 150), a coating solution having the following composition was applied to one surface at a rate of 10.0 g / m ² when dried, and dried at 100 ° C. for 30 minutes. A thermal transfer image receiving sheet was obtained.

11.5 parts of copolymer shown in Table 2 below Vinyl chloride / vinyl acetate copolymer (VYHH, UCC) 5.0
Part Amino-modified silicone (KF-393, manufactured by Shin-Etsu Chemical Co., Ltd.)
1.2 parts Epoxy-modified silicone (X-22-343, manufactured by Shin-Etsu Chemical Co., Ltd.) 1.2 parts Methyl ethyl ketone / toluene / cyclohexanone (weight ratio 4: 4: 2) 102.2 parts Table 2 No. 1: Vinyl chloride / n-butyl acrylate / Methacrylic acid (molar ratio 40/58/2) copolymer degree of polymerization 75 No.2: vinyl chloride / cyclohexyl acrylate (molar ratio 5
5/45) Copolymer Degree of polymerization 100 No.3: Vinyl chloride / 2-hydroxyethyl methacrylate / vinyl acetate (molar ratio 75/24/1) copolymer Degree of polymerization 100 No. 4: Vinyl chloride / methacrylic acid 2-Hydroxyethyl / vinyl acetate (molar ratio 80/15/5) copolymer Polymerization degree 100 No.5: Vinyl chloride / ethyl methacrylate / vinyl acetate (molar ratio 90/10) copolymer Polymerization degree 100 No. 6: vinyl chloride / iso-propyl acrylate / ethylene (molar ratio 40/55/5) copolymer degree of polymerization 100 No. 7: vinyl chloride / n-dodecyl methacrylate / styrene (molar ratio 40/55/5) Copolymer Degree of polymerization 100 No.8: Vinyl chloride / methyl acrylate (molar ratio 40/55) Copolymer Degree of polymerization 100 No. 9: Vinyl chloride / n-butyl acrylate / methacrylic acid (molar ratio 40/58) / 2) Copolymer Degree of polymerization 800 (Comparative example) No. 10: Vinyl chloride homopolymer Degree of polymerization 700 (Comparative example) No. 11: n-butyl acrylate alone Coupling Degree of polymerization 700 (Comparative example) The thermal transfer sheet and the thermal transfer image-receiving sheet of the present invention are superposed on each other with the respective dye layers and the dye-receiving surface facing each other. Recording was performed with a thermal head under the conditions of 4.0 msec., And the results shown in Table 3 below were obtained.

The color density is a densitometer manufactured by Macbeth, USA
This is a value measured by RD-918.

The fastness was evaluated as ◎ when the recorded image was left in a 50 ° C atmosphere for a long time and the sharpness of the image did not change, and the white paper was not colored even if the surface was worn with white paper. Those with no loss and slightly colored white paper were marked with ○, those with sharpness lost and colored with white paper were marked with Δ, and those with unclear images and markedly colored white paper were marked with x.

Claims (4)

(57) [Claims] 1. A substrate sheet and a dye receiving layer formed on at least one surface of the substrate sheet, wherein the dye receiving layer comprises a copolymer of vinyl chloride and an acrylic acid monomer, A thermal transfer image-receiving sheet for forming an image using a sublimation-type thermal transfer sheet and a thermal head, wherein the degree of polymerization of the copolymer is 50 to 500. 2. A thermal transfer method comprising superimposing a thermal transfer sheet having a sublimable dye layer and a thermal transfer image receiving sheet having a dye receiving layer, and heating the resulting image in an image using a thermal head to form an image on the dye receiving layer. A thermal transfer method, wherein the dye receiving layer comprises a copolymer of vinyl chloride and an acrylic acid-based monomer, and the degree of polymerization of the copolymer is 50 to 500. 3. The thermal transfer method according to claim 2, wherein the sublimable dye is a dye having an amino group. 4. The thermal transfer method according to claim 2, wherein the sublimable dye is an indoaniline-based, cyanoacetyl-based or anthraquinone-based dye.