JPH05208562A - Image receiving sheet for thermal transfer recording - Google Patents

Abstract

PURPOSE:To markedly improve recording image quality and recording sensitivity, in the title image receiving sheet receiving a transfer image from a color transfer sheet, by providing an intermediate layer containing polyvinyl alcohol resin having a specific polymerization degree between the image receiving layer and the support. CONSTITUTION:An image receiving sheet for thermal transfer recording useful for a recording system thermally transferring a colorant, especially, a heat- sublimable dye is obtained by providing an image receiving layer receiving a transfer image from a color transfer sheet on a support. In this image receiving sheet, an intermediate layer containing a polyvinyl alcohol resin with a polymerization degree of 50-450 is provided between the image receiving layer and the support. By this constitution, a recording image of high image quality excellent in recording sensitivity and extremely excellent in resolving power, sharpness, color density and missing dot resistance is obtained. The polyvinyl alcohol resin is obtained by hydrolyzing a vinyl acetate resin obtained by controlling its polymerization degree becoming essential so as to have a necessary saponification degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image-receiving sheet for thermal transfer recording, and more particularly to an improvement of an image-receiving sheet for thermal transfer recording using a thermal sublimation dye, which is remarkably improved in recording sensitivity and recording image quality. Is provided.

[0002]

2. Description of the Related Art A thermal recording system, which can obtain a recorded image at the same time as an input signal, is used in various fields such as facsimiles, computer terminal printers, measuring instrument printers, etc., because it is relatively simple and inexpensive and has low noise. Has been done. As a recording medium used in these thermal recording systems, so-called color-developing type heat-sensitive recording paper, which is provided with a recording layer that undergoes a physical or chemical change by heating to develop a color, is most commonly used.

However, the color-developing type thermosensitive recording paper is liable to cause unnecessary color development during the manufacturing process and during storage, and is also inferior in storage stability of the recorded image, so that it may come into contact with organic solvents or chemicals. Therefore, there is a drawback that the fading phenomenon is likely to occur. Therefore, a method of using a recording medium using a colored coloring material itself has been proposed as a recording medium in place of the color-developing thermal recording paper, for example, JP-A-51.
In JP-A-15446, a color material which is solid or semi-solid at room temperature is applied on a support such as paper or polymer film, and the color material on the support is brought into contact with a recording paper to perform thermal recording. A method has been proposed in which a coloring material on a support is heated by a head and selectively transferred to recording paper to obtain a recorded image.

In this recording system, the coloring material on the support is melted, evaporated and sublimated by heat and transferred to recording paper to obtain a recorded image by adhesion, adsorption and dyeing, and plain paper is also used as recording paper. There are features available. In particular, in a recording method using a sublimable dye as a color material, an image excellent in gradation can be obtained, and therefore application development for full-color recording is underway.

However, when plain paper is used as the recording paper, dyeing is difficult to occur, sufficient color density is difficult to obtain, and a remarkable fading phenomenon occurs over time. Therefore, JP-A-57-107885 and US Pat.
An image receiving sheet on which an image receiving layer containing a thermoplastic resin as a main component is formed is proposed in JP-A-601484. By forming an image receiving layer containing a thermoplastic resin as a main component,
The recording sensitivity and storability were improved, but when the support was plain paper, a uniform image-receiving layer could not be obtained, and the recording sensitivity and image quality were insufficient. Therefore, JP-A-60-23
As described in JP-A-6794, JP-A-61-144394 and the like, an intermediate layer such as a thermoplastic resin is interposed between a support and an image receiving layer, and a color material layer of a color material transfer sheet at the time of printing. There has been proposed a method for improving the recording sensitivity and the image quality by improving the adhesion between the image receiving sheet and the image receiving layer to prevent air gaps and the like from occurring.

The intermediate layer is made of a specific thermoplastic resin (Japanese Patent Laid-Open Nos. 60-236794 and 61-1443).
No. 94, No. 61-258793, No. 61-29508.
No. 5) or composed of specific resin fine particles (Japanese Patent Laid-Open No. 63-
87286, 64-27996, JP-A 1-13
No. 6784, No. 2-139293), and further improvement in image quality and / or recording sensitivity has been proposed, but in reality, satisfactory results have not been obtained.

On the other hand, it has been proposed to obtain good image quality and recording sensitivity by using a synthetic paper or a white film as a support, but it is deformed by heat applied at the time of recording and is expensive. There are still problems such as the fact that it is a different material, and it was not satisfactory.

[0008]

In view of the above situation, the present inventors have earnestly studied the improvement of an image-receiving sheet for thermal transfer recording, which is useful in a recording system in which a colored coloring material, particularly a heat sublimable dye, is thermally transferred. The present invention has completed an image-receiving sheet which has extremely high recording sensitivity and gives a recorded image of high image quality which is extremely excellent in resolution, sharpness, color density, dot dropout and the like.

[0009]

SUMMARY OF THE INVENTION The present invention provides a thermal transfer recording image-receiving sheet comprising a support and an image-receiving layer for receiving a transfer image from a color material transfer sheet, and the image-receiving layer of the image-receiving sheet and the support. An image-receiving sheet for thermal transfer recording comprising an intermediate layer containing a polyvinyl alcohol-based resin having a degree of polymerization of 50 to 450 between the body and the body.

[0010]

The image-receiving sheet for thermal transfer recording of the present invention is characterized by the composition of the intermediate layer, that is, a polyvinyl alcohol resin having a low degree of polymerization of 450 or less is essential component in the intermediate layer. It has an extremely great significance when it is included as. By providing such an intermediate layer, it is possible to obtain a recorded image of high image quality, which is excellent in recording sensitivity and is extremely excellent in resolution, definition, color density, dot dropout, and the like. Although the reason why such an effect is obtained is not necessarily clear, a specific polyvinyl alcohol-based resin that constitutes the intermediate layer exerts its characteristics during thermal transfer recording to uniformly control heat transfer from the recording head, It is presumed that this is to improve the adhesion between the color material transfer sheet and the image receiving sheet.

The polyvinyl alcohol-based resin as an essential component of the intermediate layer is obtained by hydrolyzing a vinyl acetate-based resin obtained by controlling an essential degree of polymerization by an ordinary method to a required saponification degree. , Is selected and used as a polyvinyl alcohol resin having a desired degree of polymerization.

[0012] For example, the polymerization of vinyl acetate-based monomers typified by vinyl acetate can be carried out by a conventional method such as bulk polymerization, solution polymerization, emulsion polymerization and granular polymerization, but since the degree of polymerization can be easily controlled, Solution polymerization is preferably used, and polymerization required by any method such as selection of polymerization solvent, selection of monomer and / or initiator concentration, selection of polymerization temperature and / or polymerization time, and / or use of chain transfer agent. You can control every time. Further, the hydrolysis of the vinyl acetate resin obtained above can be carried out with an alkali catalyst or an acid catalyst, but the hydrolysis reaction with an alkali catalyst is preferably used because there are few side reactions, and the amount of the alkali catalyst, The required saponification degree can be controlled by selecting the reaction temperature, reaction time, and the like. Further, for example, the saponification degree can be controlled by changing the water content at the time of hydrolysis in an alcohol solvent, and it can be preferably used.

In the present invention, a specific polyvinyl alcohol-based resin is used as an essential component of the intermediate layer, but the physical properties of the coating liquid for forming the intermediate layer are controlled, and the whiteness and opacity of the obtained intermediate layer are Organic or inorganic powders can be used in combination for the purpose of controlling the smoothness, etc., and improving the handling workability of the web during and after the formation of the intermediate layer. In particular, organic powders with low thermal conductivity. Is preferably used in combination. Examples of such organic powders include starch granules, cellulose powder, natural organic powders such as pollens, and condensation resin fine particles typified by nylon, polyester, urea, melamine and guanamine, and polyurethane. system,
Synthetic resin particles such as poly-added resin particles typified by epoxy and polymerization resin particles typified by vinyl are preferably used.

Such synthetic resin fine particles can be produced by controlling the external force at the time of resin production such as the method utilizing the morphology generation due to the progress of the polycondensation reaction from the solvent such as water, the emulsion polymerization method and the suspension polymerization method. Any method such as a direct production method, a submerged granulation method in a non-solvent, a freeze-drying method, a mechanical granulation method such as a dry and / or wet granulation method, and a post-processing treatment after resin formation Can be obtained by

Among the resin fine particles as described above, the vinyl resin particles can be easily controlled in their physical properties by selecting a monomer, and the fine particles can be easily produced.
These vinyl resin particles are synthesized by a so-called polymerization method by selecting one or more kinds of suitable monomers, and are preferably synthesized in the form of an aqueous dispersion by an emulsion polymerization method, a suspension polymerization method or the like. Specific examples of the main component monomer include, for example, styrene, α-methylstyrene, 4-methylstyrene, 2-methylstyrene, 4-methoxystyrene, vinyl chloride, vinylidene chloride, ethylene, vinylcyclohexane, methyl methacrylate, hexyl acrylate. ,
Vinyl-based monomers such as vinyl acetate and acrylonitrile can be mentioned. For example, melting point, softening point, glass of resin particles by adding a rubber-based monomer such as 1,3-butadiene, isoprene, and 2-chloro-1,3-butadiene. The melting point, softening point and glass transition point of the resin particles can be increased by lowering the transition point or by adding a crosslinking agent such as divinylbenzene.

Further, in order to modify the surface characteristics of the resin particles, an α, β-ethylenically unsaturated carboxylic acid monomer such as acrylic acid, methacrylic acid, maleic acid, itaconic acid or fumaric acid is added and copolymerized. It can also be modified by a polymer reaction or the like. Furthermore, it is also possible to modify the so-called ionomer resin by metal crosslinking. It should be noted that these resin fine particles are known and can be used in any shape such as sphere, flat, konpeito, snow dharma, wild strawberry, star, and indefinite shape, but spherical particles have remarkable effects in the present invention. And is preferably used.

These spherical particles may be homogeneous inside, or may be particles having a heterogeneous structure such as a multi-layered structure or a polynuclear structure. Further, thermal expansion containing a non-expandable hollow resin fine particle (for example, manufactured by Rohm and Haas Co .; Rhopaque, etc.) having an internal void during the production of such resin particle, and a foaming agent which can be used as the hollow resin fine particle by heat foaming when necessary Fine resin particles (for example, Matsumoto Yushi Co., Ltd .; Microsphere, Nippon Philite Co .; EXPANCEL, etc.), and USP
As exemplified in Japanese Patent No. 4722943, composite thermoplastic resin fine particles whose surface is coated with an inorganic powder are also preferably used.

Examples of the inorganic powder include clay, kaolin, calcined kaolin, delaminated kaolin, structural kaolin, aluminum hydroxide, titanium dioxide, barium sulfate, zinc oxide, satin white, talc, silica and the like. So-called inorganic pigments used in the coating field are used, but they are used within a range that does not impair the effects of the present invention.

Further, in the coating liquid for forming the intermediate layer, if necessary, for example, addition of various binders for improving adhesion, fluidity, etc., dyes, pigments for controlling color tone, whiteness and the like, and / Or fluorescent dyes, UV absorbers for improving storage stability, antioxidants, etc., dispersants for improving smearability, wetting agents, antifoaming agents, etc. Various auxiliaries known in the art, such as a fungicide, an antistatic agent, a water resistant agent, and a crosslinking agent, can be added.

Examples of binders include natural or semi-synthetic polymers such as modified starch, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, casein, gelatin and natural rubber; the degree of polymerization is 450.
Exceeding polyvinyl alcohol, isoprene, neoprene, polydienes such as polybutadiene, polybutene, polyisobutylene, polypropylene, polyalkenes such as polyethylene, vinyl halide, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic ester, ( Vinyl-based polymers and copolymers such as (meth) acrylamide and methyl vinyl ether, polyesters, polyurethanes, polyamides, styrene-butadiene-based polymers,
Specific examples of so-called coating binders such as synthetic polymers such as synthetic rubber latex such as methylmethacrylate / butadiene / maleic acid type are added if necessary, but a specific polyvinyl alcohol type resin which is an essential component of the present invention. In general, it is desirable to add 500% by weight or less.

By performing a smoothing treatment before or after forming the image receiving layer on the intermediate layer thus formed, the image quality and the recording sensitivity of the obtained image receiving sheet can be further enhanced. The smoothing treatment is appropriately performed by heating and / or pressurizing treatment using, for example, a super calender, a gross calender, a cast drum, etc. At this time, addition of the spherical resin fine particles, particularly addition of resin fine particles having a specific particle diameter is not performed. It is effective, for example, the average particle diameter of the resin fine particles is 0.
If it is 1 μm or less, the smoothing effect is small, and conversely 1
If it exceeds 00 μm, not only the coating suitability but also the effect of the smoothing treatment cannot be expected. Therefore, it is desirable to use resin fine particles of 0.2 to 50 μm in combination. The amount used cannot be generally determined depending on the material, particle size, shape, etc. of the fine particles used, but is generally about 1/100 to 100/1, preferably 1/100 to the specific polyvinyl alcohol resin, which is an essential component. Combined use within the range of 20 to 20/1 is desirable.

In the image-receiving sheet of the present invention, the image-receiving layer provided on the above-mentioned intermediate layer is not particularly limited, but generally a thermoplastic resin layer having an effective dyeing ability for a sublimable dye is preferable. Used. Examples of the thermoplastic resin constituting the image receiving layer include polymers and copolymers of vinyl monomers such as styrene, vinyltoluene, acrylic acid ester, methacrylic acid ester, acrylonitrile, vinyl chloride and vinyl acetate; polyester,
Examples thereof include condensation polymers such as polyamide, polycarbonate, polysulfone, epoxy resin and polyurethane; and cellulose resins. These thermoplastic resins may be used alone, or two or more kinds of resins having different properties may be used in combination.

If necessary, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, starch, polyvinyl alcohol, polyamide resin, phenol resin, melamine resin, urea resin, urethane resin, epoxy resin, silicone resin, fluorine resin, etc. May be contained a resin material, a polyvalent isocyanate compound,
It is also possible to modify the image receiving layer by adding a reactive compound such as an epoxy compound or an organometallic compound. But,
It is necessary to keep the thermoplastic synthetic resin constituting the image receiving layer within the range in which the thermoplasticity is not lost.

Further, for the purpose of improving the writing property, the image-receiving layer is, for example, heavy or light calcium carbonate, talc, clay, natural or synthetic silicic acid, titanium oxide, aluminum hydroxide, zinc oxide, urea formaldehyde resin powder, etc. It is also possible to add various auxiliaries such as inorganic and organic pigments, ultraviolet absorbers, antioxidants, antistatic agents, release agents and lubricants.

The coating amount of the constituents forming the image-receiving layer on the intermediate layer is appropriately selected according to the purpose of use of the image-receiving sheet, but generally the dry weight is about ² to 15 g / m ^2. Be engineered. As the support, plain paper, synthetic paper, synthetic resin film or the like is appropriately selected and used, but plain paper is preferably used because it has excellent thermal characteristics. Further, the plain paper referred to herein is, for example, a paper obtained by ordinary paper-making with cellulose pulp as a main component and adding a paper-strengthening agent, a sizing agent, a fixing agent, an inorganic and an organic filler, and the like. Includes papers whose surface properties have been improved by size-pressing oxidized starch, etc., or by providing a pre-coating layer mainly composed of pigments such as clay, but the surface is smooth such as art paper, coated paper, cast coated paper, etc. Paper having excellent properties is particularly preferably used.

These supports may be provided with an image-receiving layer after providing an intermediate layer, but if necessary, before and / or after providing the intermediate layer, control of adhesiveness, barrier property, smoothness, hiding property, smearing suitability and the like can be performed. It is optional to further provide an anchor coat layer or to extrude and laminate a thin film base material for the purpose, and known materials and methods can be used.

On the image receiving layer, for example, JP-A-59 is used.
No. 165688, JP-A No. 61-27290, etc., a thin heat-resistant release layer containing a silicon-based resin having a property of transmitting a sublimation dye as a main component is formed, It is also possible to prevent the dye or dye layer from being directly transferred from the color material transfer sheet. Further, in order to improve the handleability and / or printer suitability of the obtained image-receiving sheet for thermal transfer recording, for example, a back coat layer is provided for the purpose of preventing curling, controlling slipperiness, giving writability, or the like, or Applying antistatic treatment to the front surface and / or back surface, etc.
Treatment by a conventional method in the technical field is also optional.

The thus obtained image-receiving sheet for thermal transfer recording of the present invention exhibits extremely excellent performance particularly as an image-receiving sheet when a sheet containing a heat sublimable dye is used as a color material transfer sheet, It has excellent recording sensitivity and can provide a recorded image with high image quality, which is extremely excellent in resolution, definition, color density, dot dropout, and the like.

The heat sublimable dye referred to in the present invention does not cause the color material to transfer even when it comes into contact with the image receiving sheet under normal handling conditions, but it is first melted, evaporated or sublimated by heating at 60 ° C. or higher. Etc. means a dye that causes a transition of a coloring material, for example, an azo type, a nitro type, an anthraquinone type, a disperse dye represented by a quinoline type, a triphenylmethane type, a basic dye represented by a fluorane type, It is used by appropriately selecting from various dyes such as oil-soluble dyes.

Further, the image-receiving sheet for thermal transfer recording of the present invention is not limited to a thermal recording system of contact heating with a thermal plate such as a thermal printing unit or a thermal head, but also a heat ray of an infrared lamp, a YAG laser, a carbon dioxide gas laser or the like. It is also useful for thermal recording by a non-contact heating method using radiation.

Hereinafter, the present invention will be described in more detail with reference to examples, but it goes without saying that the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples mean "parts by weight" and "% by weight", respectively.

Examples Examples 1 to 7 and Comparative Examples 1 to 4 As shown in Table 1, benzoguanamine resin powder (trade name: Eposter MS, spherical, average particle diameter 2 μm, manufactured by Nippon Shokubai Co., Ltd.) was added to various polyvinyl alcohol resin solutions. ) Is dispersed and mixed using a stirrer to prepare a coating liquid for the intermediate layer,
It was coated and dried on a commercially available high-quality paper (trade name: TKP-13, basis weight 81 g / m ² , manufactured by Kanzaki Paper Co., Ltd.) so that the dry weight was 7 g / m ² .

[0033]

[Table 1]

Then, an aqueous polyester resin (trade name:
Bayronal MD-1200, 34% solid content, Toyobo Co., Ltd.)
Was coated and dried on the intermediate layer to a dry weight of 4 g / m ² to form an image-receiving layer, and then smoothed with a super calender consisting of mirror-finished metal rolls and elastic rolls (linear pressure 200 kg / cm 2 ) Was done.

Next, 100 parts of saturated polyester resin (trade name: Byron 200, manufactured by Toyobo Co., Ltd.), amino-modified silicone oil (trade name: KF-393, manufactured by Shin-Etsu Silicone Co., Ltd.)
1.5 parts, epoxy modified silicone oil (trade name: X-
22-343, manufactured by Shin-Etsu Silicone Co., Ltd.) 1.5 parts in methyl ethyl ketone / toluene (weight ratio 1/1) with stirring with a mixer, mixed and dissolved to prepare a coating solution, and the image-receiving layer obtained above Dry weight of 2g / m ² on the above and dried at 100 ℃
Was heat-cured for 2 minutes to obtain an image-receiving sheet for thermal transfer recording.

Comparative Example 5 An image receiving sheet for thermal transfer recording was obtained in the same manner as in Example 1 except that the intermediate layer was not provided.

With respect to the 12 types of thermal transfer recording image-receiving sheets thus obtained, a quality comparison test was conducted as follows,
The results are shown in Table 2. "Quality comparison test" Blue heat sublimation dye (Product name: KST-B-71
4, manufactured by Nippon Kayaku Co., Ltd.) 4 parts, polyvinyl butyral resin (trade name: S-REC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 4 parts by methyl ethyl ketone / toluene (weight ratio 1/1) 10
It is dissolved in 0 parts and applied as a color material layer forming ink onto a polyester film having a thickness of 6 μm, which is heat-treated on the back side, so that the dry weight is 1 g / m ² , and the color material is transferred. Created a sheet.

Next, the coating surfaces of the color material transfer sheet and the image receiving sheet for thermal transfer recording are superposed on each other, and heat is applied from the back surface of the color material transfer sheet by a thermal head (12 V, 4 to 16 msec).
A thermal transfer recording image was formed on the image receiving layer surface of the image receiving sheet, and the recording density and the image quality of each image receiving sheet and the recorded image were evaluated as follows. [Recording Density] The recording density was measured with a Macbeth densitometer (RD-914). [Image Quality] The image in the highlight part (7 ms) was observed with a 25 × magnifying glass to evaluate dot reproducibility and dot dropout. [Evaluation Criteria] A: No dot omission and excellent dot reproducibility. B: No dot dropout and excellent dot reproducibility. C: There are some missing dots, but dot reproducibility is at a practical level. D: Dotted omission is conspicuous and there is a problem in practicality. E: Dot loss and reproducibility are poor and practical.

[0039]

[Table 2]

[0040]

As is clear from the results of the table, the image-receiving sheets for thermal transfer recording obtained in the examples of the present invention have not only excellent recording sensitivity but also extremely clear and high color density recorded images, It was an image-receiving sheet for thermal transfer recording which was particularly excellent in image quality.

Claims (1)

[Claims] 1. A thermal transfer recording image-receiving sheet comprising a support and an image-receiving layer for receiving a transfer image from a color material transfer sheet, wherein the degree of polymerization is 50 between the image-receiving layer of the image-receiving sheet and the support. An image receiving sheet for thermal transfer recording, which is provided with an intermediate layer containing 450 to 450 polyvinyl alcohol resin.