JP2993972B2 - Thermal transfer image receiving sheet - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermal transfer image-receiving sheet useful in a thermal transfer method using a sublimable dye (heat-migrating dye), and more specifically, to use a usual release agent. It is an object of the present invention to provide a thermal transfer image-receiving sheet capable of performing high-speed recording without forming a high-density and high-resolution transfer image.

(Conventional Technology and Problems Thereof) As a method for easily and quickly providing an excellent mono-color or full-color image instead of the conventional general printing method or printing method, an ink-jet method and a thermal transfer method have been developed. Among these, the so-called sublimation thermal transfer method using a sublimable dye is the most excellent, as it has excellent continuous gradation and gives a full-color image comparable to a color photograph.

The thermal transfer sheet used in the above sublimation type thermal transfer method is
In general, a dye sheet containing a sublimable dye is formed on one surface of a base material sheet such as a polyester film, and a heat-resistant layer is provided on the other surface of the base material sheet to prevent adhesion of a thermal head. Used.

The dye layer surface of such a thermal transfer sheet is overlaid on an image receiving sheet having an image receiving layer made of polyester resin or the like, and the dye in the dye layer is transferred to the image receiving sheet by heating the image back from the back of the thermal transfer sheet. Thus, a desired image is formed.

The thermal transfer method as described above has an excellent advantage that the density of an image can be obtained depending on the level of the temperature of the thermal head.However, when the temperature of the thermal head is increased to increase the density, the dye layer is formed. The disadvantage that the binder being formed is softened and adheres to the image receiving sheet and the thermal transfer sheet and the image receiving sheet adhere to each other,
In a more extreme case, a problem arises in that the dye layer is peeled off at the time of peeling and transferred to the surface of the image receiving sheet as it is.

As a method for solving such a problem, a release agent such as silicone oil is contained in the dye receiving layer of the image receiving sheet. However, since the silicone oil is liquid at normal temperature, it is stored during storage. However, there is a drawback in that it is raised on the surface of the receptor layer and causes problems of blocking and contamination. On the other hand, there is a method using a thermosetting silicone oil. However, these methods require a heat treatment after the formation of the receptor layer, and have a problem that the production process is very complicated.

Furthermore, if a relatively large amount of silicone is added to give sufficient releasability to the receiving layer, the receptivity of the dye is reduced,
This causes a problem that the image receiving sheet is discolored and storage stability is deteriorated.

Further, it is conceivable that the dye receiving layer is formed of a silicone acrylic block copolymer resin having releasability by itself, but the receiving layer made of the resin has an adhesive property with the base sheet,
There is a problem in that the acceptability of the dye is insufficient and the ink is hard and lacks cushioning properties, so that white spots occur during printing, and high-density and high-resolution images cannot be formed.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a thermal transfer image-receiving sheet capable of high-speed recording and forming a high-density and high-resolution transfer image without using a release agent when forming a receptor layer.

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

That is, the present invention relates to a thermal transfer image-receiving sheet having a dye-receiving layer provided on the surface of a base sheet, wherein at least 30% by weight of the resin constituting the dye-receiving layer is graft-bonded to the main chain of a polysiloxane segment, A thermal transfer image-receiving sheet, which is a graft copolymer containing 3 to 60% by weight of at least one releasable segment selected from a carbon segment and a long-chain alkyl segment.

(Function) By forming the dye-receiving layer from a polymer having good dye-dyeing properties onto which a releasable segment is grafted, it is possible to use the dye-releasing property, dye-dyeing property and base material without using the releasability. An image receiving sheet having excellent adhesion and the like can be obtained.

That is, in the present invention, the polymer for forming the dye-receiving layer is a polymer having at least one type of releasable segment, and if this is schematically represented, as shown in FIG. In contrast, the releasable segment is graft-bonded as a side chain.

The releasable segments of such polymers themselves generally have low compatibility with the polymer backbone. Thus, when a dye receiving layer is formed from such a polymer, the releasable segments tend to microphase separate from the dye receiving layer and bleed to the surface of the dye receiving layer. On the other hand, the main chain is integrally bonded to the base sheet. When these effects are achieved, the releasable segment becomes rich on the surface of the dye receiving layer as shown in FIG. However, the releasable segment is not separated from the dye receiving layer by the main chain, and thus the releasable segment does not migrate to the surface of another article. Also, by selecting a good dye-dyeing property as the main chain,
Excellent dye-dyeing properties can be provided.

(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 substrate sheet and a dye-receiving layer provided on at least one surface thereof with a releasable graft copolymer.

As the base sheet used in the present invention, 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 Various plastic films or sheets such as impregnated paper, paper with synthetic resin, paperboard, cellulose fiber paper, polyolefin, polyvinyl chloride, polyethylene terephthalate, polystyrene, polymethacrylate, and polycarbonate can be used. A white opaque film formed by adding a white pigment or a filler to a resin, a foamed foamed sheet, or the like can be used, and is not particularly limited. Also, a laminate formed by any combination of the above 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 thickness of these base sheets may be arbitrary, and for example, a thickness of about 10 to 300 μm is generally used.

When the base sheet as described above has a poor adhesion to the receiving layer formed on the surface, it is preferable to subject the surface to a primer treatment or a corona discharge treatment.

The dye receiving layer formed on the surface of the base sheet receives the sublimable dye transferred from the thermal transfer sheet and maintains the formed image.

In the present invention, the polymer forming the dye receiving layer is
A graft copolymer having at least one releasable segment selected from a polysiloxane segment, a fluorocarbon segment, and a long-chain alkyl segment grafted to the main chain.

As the polymer as the main chain, any conventionally known polymer having a reactive functional group can be used. Preferred examples thereof include ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxycellulose, hydroxypropyl cellulose, methyl cellulose, cellulose acetate, and vinegar. Cellulose resins such as cellulose butyrate, acrylic resins, polyvinyl resins such as polyvinyl alcohol, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal, polyvinyl pyrrolidone, polyacrylamide, polyamide resins, polyurethane resins, polyester resins, and the like. Of these, acrylic, vinyl, polyester, polyurethane, polyamide and cellulose resins are particularly preferred from the viewpoint of dye dyeing properties.

The releasable graft copolymer used in the present invention can be synthesized by various methods. One preferable method is to form, after the main chain is formed, a functional group present in the main chain, A method of reacting a release compound having a reactive functional group is exemplified.

As an example of the release compound having the above functional group, the following compounds may be mentioned.

(A) Polysiloxane compound In the above formula, part of the methyl group may be substituted with another alkyl group or an aromatic group such as a phenyl group.

(B) Carbon fluoride compound (8) C ₈ F ₁₇ C ₂ H ₄ OH (9) C ₆ F ₁₃ C ₂ H ₄ OH (11) C ₈ F ₁₇ C ₂ H ₄ OH (12) C ₁₀ F ₂₁ C ₂ H ₄ OH (13) C ₈ F ₁₇ SO ₂ N (C ₂ H ₅ ) C ₂ H ₄ OH (14) C ₈ F ₁₇ SO ₂ N (C ₂ H ₅ ) C ₂ H ₄ OH (15) C ₆ F ₁₃ COOH (16) C ₆ F ₁₃ COCl (17) C ₈ F ₁₇ C ₂ H ₄ SH (C) long-chain alkyl compounds higher fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid and their acid halides, nonyl alcohol, caprylic alcohol, lauryl alcohol, myristyl alcohol;
Higher alcohols such as cetyl alcohol, stearyl alcohol, oleyl alcohol, linoleyl alcohol, and ricinoleyl alcohol; higher aldehydes such as caprinaldehyde, laurinaldehyde, myristic aldehyde, and stearaldehyde; higher amines such as decylamine, laurylamine, and cetylamine.

The above examples are merely examples, and various other reactive release compounds can be obtained from, for example, Shin-Etsu Chemical Co., Ltd., and any of them can be used in the present invention. Particularly preferred is a monofunctional release compound having one functional group in one molecule, and when a polyfunctional compound having two or more functionalities is used, the obtained graft copolymer is used. Are not preferred because they tend to gel.

The relationship between the functional release compound and the resin as exemplified above is as shown in Table 1 below, where the functional group of the release compound is represented by X and the functional group of the polymer is represented by Y. Of course, X
And the relationship between Y and Y may be reversed, or may be used as a mixture, and the present invention is not limited to these examples as long as both react.

Further, as another preferred production method, the functional release compound is reacted with a vinyl compound having a functional group that reacts with the functional group to obtain a monomer having a release segment. The desired graft copolymer can be similarly obtained by copolymerizing with the above.

As still another preferred production method, the polymer having an unsaturated double bond in the main chain thereof, such as an unsaturated polyester or a copolymer of a vinyl monomer and a diene compound such as butadiene, is used. ) And a method of adding and grafting a mercapto compound or the above-mentioned releasable vinyl compound.

The above is an example of a preferable production method, and the present invention can naturally use a graft copolymer produced by other methods.

The content of the releasable segment in the polymer,
3-60% by weight of releasable segments in the polymer
Range. When the amount of the releasable segment is too small, the releasability becomes insufficient.On the other hand, when the amount is too large, the migration of the dye and the film strength are reduced, and the problem of discoloration and storage of the dye occurs, which is preferable. Absent.

The thermal transfer image-receiving sheet of the present invention is obtained by dissolving a resin obtained by adding the necessary additives to the resin as described above on at least one surface of the base sheet in a suitable organic solvent or dispersing in an organic solvent or water. The dispersion thus obtained can be obtained by coating and drying by a forming means such as a gravure 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, a conventionally known resin for forming a receiving layer can be used in combination. When these known resins are used in combination, the proportion of the graft copolymer accounts for at least 30% by weight of the whole resin. In forming the receiving layer, the whiteness of the receiving layer is improved to improve the transfer image. For the purpose of further increasing the definition, pigments and fillers such as titanium oxide, zinc oxide, kaolin clay, calcium carbonate, and finely divided silica can be added.
Further, in order to further improve the discoloration resistance of the transferred image formed on the receiving layer, particularly the discoloration resistance in a room and the discoloration resistance in a dark place, an ultraviolet absorber or an antioxidant may be added to the receiving layer. I can do it.

The dye-receiving 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 may be formed as a discontinuous coating using a resin emulsion or a resin dispersion.

The image-receiving sheet of the present invention can be applied to various uses such as a heat-transferable recording sheet, cards, and a sheet for making a transmission type original by appropriately selecting a base sheet.

Furthermore, the image receiving sheet of the present invention can have a cushion layer between the base sheet and the receiving layer if necessary, and by providing such a cushion layer, noise during printing can be reduced to correspond to image information. Images can be transferred and recorded with good reproducibility.

Further, a lubricating layer can be provided on the back surface of the base sheet. Examples of the material of the lubricating layer include a methacrylate resin such as methyl methacrylate or a corresponding acrylate resin, and a vinyl resin such as a vinyl chloride-vinyl acetate copolymer.

Furthermore, it is also possible to provide a detection mark on the image receiving sheet. The detection mark is extremely convenient when positioning the thermal transfer sheet and the image receiving sheet. For example, a detection mark that can be detected by a photoelectric tube detection device can be provided on the back surface of the base sheet by printing or the like.

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 polyester film. Any of them can be used as it is in the present invention.

As a means for applying thermal energy at the time of thermal transfer using the image receiving sheet of the present invention, any conventionally known applying means can be used, for example, a thermal printer (for example, Video Printer VY-100, manufactured by Hitachi, Ltd.) or the like. 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 by the recording apparatus of (1).

(Effects) According to the present invention as described above, by forming the dye receiving layer from a specific resin, the release property, the dye dyeing property, the adhesive property to the substrate and the cushion can be achieved without using a release agent. An image receiving sheet having excellent properties can be obtained.

Accordingly, it is possible to provide a thermal transfer image receiving sheet capable of preventing fusion with a thermal transfer sheet at the time of transfer without using a release agent that causes various problems, and capable of forming a high-speed, high-density and high-resolution image.

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

Reference Example 1 Copolymer of 95 mol% of methyl methacrylate and 5 mol% of hydroxyethyl methacrylate (molecular weight: 120,000) 4
0 parts of a mixed solvent of an equal amount of methyl ethyl ketone and toluene 4
Then, 10 parts of the above-mentioned polysiloxane compound (5) (molecular weight: 3,000) was gradually added dropwise, and reacted at 60 ° C. for 5 hours. The product was a homogeneous product, and the polysiloxane compound could not be separated by the fractional precipitation method, and the polysiloxane compound reacted with the acrylic resin. Analysis showed that the amount of polysiloxane segment was about 7.4%.

Reference Example 2 Polyvinyl butyral (degree of polymerization 1,700, hydroxyl group content 33
(Mol%) of 50 parts was dissolved in 500 parts of a mixed solvent of the same amount of methyl ethyl ketone and toluene, and then 10 parts of the above-mentioned polysiloxane compound (5) (molecular weight: 3,000) was gradually added dropwise and reacted at 60 ° C. for 5 hours. Was. The product was a homogeneous product, and the polysiloxane compound could not be separated by the fractional precipitation method, and the polysiloxane compound reacted with the polyvinyl butyral resin. Analysis showed that the amount of polysiloxane segment was about 5.2%.

Reference Example 3 Polyester composed of 45 mol% of dimethyl terephthalate, 5 mol% of dimethyl monoaminoterephthalate and 50 mol% of trimethylene glycol (molecular weight: 2
70 parts of 5,000) was dissolved in 700 parts of a mixed solvent of the same amount of methyl ethyl ketone and toluene, and then 10 parts of the above-mentioned polysiloxane compound (4) (molecular weight 10,000) was gradually added dropwise and reacted at 60 ° C. for 5 hours. . The product was a homogeneous product, and the polysiloxane compound could not be separated by the fractional precipitation method, and the polysiloxane compound reacted with the polyester resin. Analysis showed that the amount of polysiloxane segment was about 5.4%.

Reference Example 4 80 parts of a polyurethane resin (molecular weight: 6,000) obtained from polyethylene adipate diol, butane diol, and hexamethylene diisocyanate were dissolved in 800 parts of a mixed solvent of an equal amount of methyl ethyl ketone and toluene, and then the polysiloxane compound (6 ) (Molecular weight 2,00
0) 10 parts were gradually added dropwise and reacted at 60 ° C. for 5 hours. The product was a homogeneous product, and the polysiloxane compound could not be separated by the fractional precipitation method, and the polysiloxane compound reacted with the polyurethane resin. Analysis shows that the amount of polysiloxane segment is about
It was 4.0%.

Reference Example 5 Monomer 5 mol%, methyl methacrylate 45 mol%, butyl acrylate 40 mol%, obtained by reacting the polysiloxane compound (3) (molecular weight 1,000) with methacrylic acid chloride at a molar ratio of 1: 1. 100 parts of a mixture of 10 mol% of styrene and 3 parts of azobisisobutyronitrile were dissolved in 1,000 parts of a mixed solvent of equivalent amounts of methyl ethyl ketone and toluene, and polymerized at 70 ° C. for 6 hours to obtain a viscous polymerization liquid. The product was a homogeneous product, and the polysiloxane compound could not be separated by the fractional precipitation method.
Analysis shows that the amount of polysiloxane segment is about 6.1
%Met.

Reference Example 6 50 parts of a styrene-butadiene copolymer (molecular weight 150,000, butadiene 10 mol%) and azobisisobutyronitrile 2
Part of a mixed solvent of an equal amount of methyl ethyl ketone and toluene 50
0 parts, and then 10 parts of the above-mentioned polysiloxane compound (7) (molecular weight 10,000) was gradually added dropwise, and reacted at 60 ° C. for 5 hours. The product was a homogeneous product, and the polysiloxane compound could not be separated by the fractional precipitation method, and the polysiloxane compound reacted with the copolymer. Analysis showed that the amount of polysiloxane segments was about 6.2%.

Reference Example 7 80 parts of hydroxyethyl cellulose was dissolved in 800 parts of a mixed solvent of the same amount of methyl ethyl ketone and toluene, and then the above-mentioned polysiloxane compound (6) (molecular weight: 2,000)
0) 10 parts were gradually added dropwise and reacted at 60 ° C. for 5 hours. The product was a homogeneous product, and the polysiloxane compound could not be separated by the fractional precipitation method, and the polysiloxane compound reacted with hydroxyethyl cellulose. Analysis showed that the amount of polysiloxane segment was about 5.8%.

REFERENCE EXAMPLE 8 Instead of the polysiloxane compound in Reference Example 1, the carbon fluoride compound (16) exemplified above was used.
In the same manner as in the above, a releasable graft copolymer was obtained.

REFERENCE EXAMPLE 9 Instead of the polysiloxane compound in Reference Example 2, the carbon fluoride compound (18) exemplified above was used.
In the same manner as in the above, a releasable graft copolymer was obtained.

Reference Example 10 A releasable graft copolymer was obtained in the same manner as in Reference Example 5, except that the methacrylate of the above-mentioned carbon fluoride compound (10) was used instead of the polysiloxane compound in Reference Example 5.

Reference Example 11 A releasable graft copolymer was obtained in the same manner as in Reference Example 5, except that laurylaminoacrylate was used instead of the polysiloxane compound in Reference Example 5.

Reference Example 12 In place of the polysiloxane compound in Reference Example 5, methacrylate of vinyl stearate and the above-mentioned carbon fluoride compound (14) was used in a molar ratio of 1: 1.
In the same manner as in the above, a releasable graft copolymer was obtained.

Examples 1 to 12 Synthetic paper (Yupo-FRG-150, thickness 150) was used as the base sheet.
μm, manufactured by Oji Yuka Co., Ltd.), and applying and drying a coating solution having the following composition at a ratio of 5.0 g / m ² when dried with a bar coater on one surface to obtain a thermal transfer image-receiving sheet of the present invention. Was.

Composition for receiving layer: 15.0 parts of graft copolymer of reference example Solvent (butyl acetate / toluene / xylene (2/1/2) 85.0 parts Comparative Example 1 95 mol% of methyl methacrylate and hydroxyethyl were used in place of the graft copolymer of the example. Methacrylate 5
A thermal transfer image-receiving sheet of a comparative example was obtained in the same manner as in Example except that 4.0 parts by mol of a copolymer and 0.3 part of silicone oil (trade name: KF-96, manufactured by Shin-Etsu Chemical Co., Ltd.) were used.

Comparative Example 2 A thermal transfer image-receiving sheet of a comparative example was obtained in the same manner as in the example except that 4.0 parts of polyvinyl butyral (polymerization degree: 1,700, hydroxyl group content: 33 mol%) was used instead of the graft copolymer of the example.

Prepare an ink composition for forming a dye layer having the following composition, apply it to a 6 μm-thick polyethylene terephthalate film having a heat-resistant rear surface, and apply and dry it with a wire bar so that the dry application amount becomes 1.0 g / m ^2. A thermal transfer sheet was obtained.

Disperse dye (Kayaset Blue 714, manufactured by Nippon Kayaku) 4.0 parts Polyvinyl butyral resin (ESLEC BX-1, manufactured by Sekisui Chemical) 4.3 parts Fluorinated fatty acid-modified silicone wax (X-24-3525,
0.4 parts Methyl ethyl ketone / toluene (weight ratio 1/1) 80.0 parts Isobutanol 10.0 parts The above-mentioned thermal transfer image-receiving sheet and the above-mentioned thermal transfer sheet were
Thermal dye sublimation transfer printer (VY-50, manufactured by Hitachi, Ltd.)
The recording was performed with a thermal head from the back surface of the thermal transfer sheet at a printing energy of 90 mJ / mm ² using the above method, and the results shown in Table 2 below were obtained.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a graft copolymer used in the present invention, and FIG. 2 is a schematic diagram of a dye receiving layer.

Claims (2)

(57) [Claims] In a thermal transfer image-receiving sheet having a dye-receiving layer provided on the surface of a substrate sheet, at least 30% by weight of the resin constituting the dye-receiving layer comprises a polysiloxane segment graft-bonded to the main chain, A thermal transfer image-receiving sheet comprising a graft copolymer containing 3 to 60% by weight of at least one release segment selected from a segment and a long-chain alkyl segment. 2. The thermal transfer image-receiving sheet according to claim 1, wherein the main chain of the graft copolymer is an acrylic, vinyl, polyester, polyurethane, polyamide or cellulose resin.