JPH05229267A - Image receiving sheet for thermal transfer recording - Google Patents

Abstract

(57) [Summary] [Purpose] Excellent recording sensitivity, extremely clear and high color density,
Moreover, the present invention provides an image receiving sheet for thermal transfer recording which is excellent in image quality. A thermal transfer recording image-receiving sheet, characterized in that an intermediate layer containing a vinyl acetate resin having a sulfonic acid group is provided between the support and the image-receiving layer of the thermal transfer recording image-receiving sheet.

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 heat sublimable dye, which is remarkably improved in image quality and recording sensitivity. 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 the recording medium used in these thermal recording systems, so-called color-developing type thermal recording paper 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, as a recording medium replacing the color-developing type thermal recording paper, a system using a recording medium using a colored coloring material itself has been proposed, for example, JP-A-51-15.
Japanese Patent No. 446 discloses a thermal recording head in which a coloring material that is solid or semi-solid at room temperature is coated on a support such as paper or polymer film, and the coloring material on the support is brought into contact with the recording paper. Has proposed a method in which a coloring material on a support is heated and selectively transferred to a recording paper to obtain a recorded image.

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

However, when plain paper is used as the recording paper, dyeing is difficult to occur, sufficient color density is difficult to obtain, and a marked fading phenomenon occurs over time. Therefore, JP-A-57-107885 and US Pat.
An image receiving sheet having an image receiving layer containing a thermoplastic resin as a main component is proposed in Japanese Patent No. 01484. By forming an image-receiving layer containing a thermoplastic resin as a main component, recording sensitivity and storability are improved, but when the support is plain paper, a uniform image-receiving layer cannot be obtained and the recording sensitivity is improved. The image quality was 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, recording sensitivity, and the like have been proposed. But,
The reality is that 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 the support, but it is deformed by heat applied during recording and is expensive. There were problems such as the material being used, 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]

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, the support of the image-receiving sheet and the image-receiving layer. An image-receiving sheet for thermal transfer recording, characterized in that an intermediate layer containing a vinyl acetate resin having a sulfonic acid group is provided between and.

[0010]

The image-receiving sheet for thermal transfer recording of the present invention is characterized by the composition of the intermediate layer, and has a very important significance when it contains a vinyl acetate resin having a sulfonic acid group as an essential component of the intermediate layer. It is a thing. The image-receiving sheet for thermal transfer recording thus obtained is excellent in recording sensitivity and can provide a recorded image of high image quality which is extremely excellent in resolution, sharpness, color density, dot dropout and the like. The reason why such an effect is obtained is not necessarily clear, but the specific vinyl acetate resin that constitutes the intermediate layer exhibits its characteristics during thermal transfer recording, and uniformly controls the 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.

In the thermal transfer recording image-receiving sheet of the present invention, the vinyl acetate resin having a sulfonic acid group which is an essential component of the intermediate layer is, for example, ethylene sulfonic acid,
Of monomers containing sulfonic acid groups such as allyl sulfonic acid, methallyl sulfonic acid, sulfoalkyl acrylic acid ester, sulfoalkyl methacrylic acid ester, sulfoalkyl maleic acid ester, 2-acrylamido-2-methylpropanesulfonic acid One or more,
It is a resin obtained by copolymerizing an organic acid vinyl monomer typified by vinyl acetate with other monomers as necessary. Then, it is produced by a conventional method such as bulk polymerization, solution polymerization, emulsion polymerization, and granular polymerization, but solution polymerization is particularly preferably used because the degree of polymerization can be easily controlled. Also, selection of polymerization solvent, selection of monomer and initiator concentration, selection of polymerization temperature and polymerization time,
Furthermore, the degree of polymerization is appropriately controlled by using a chain transfer agent or the like.

In the image-receiving sheet of the present invention, if the content of the sulfonic acid group in such a copolymer is less than 0.05 mol%, the desired effect cannot be obtained, and conversely, if it exceeds 15 mol%, Not only is it uneconomical, but the effect tends to be reduced, so the sulfonic acid group content is preferably adjusted to the range of 0.05 to 15 mol%, more preferably 0.1 to 5 mol%. .. In addition, in order to control the solubility and viscosity of the copolymer, a part of the organic acid vinyl ester group is hydrolyzed (saponified) by a conventional method to introduce a vinyl alcohol group, or converted into formal or acetal. However, in the present invention, the presence of the organic acid vinyl ester group is essential, and the saponification degree must be at least 90% or less, more preferably 50% or less. Specific examples of the vinyl acetate-based resin having a sulfonic acid group used in the present invention include Gocelan L-030 from Nippon Synthetic Chemical Industry Co., Ltd.
It is marketed under the trade name of 1, L-0302, L-3266.

The image-receiving sheet of the present invention uses the above specific vinyl acetate resin as an essential component of the intermediate layer. However, the physical properties of the coating solution for forming the intermediate layer, the whiteness of the intermediate layer, and the Organic and inorganic powders may be used in combination for the purpose of controlling transparency, smoothness and the like, and further improving the workability of handling the web. In particular, it is preferable to use organic powder having a low thermal conductivity. As the organic powder, for example, starch particles, cellulose powder, natural organic powder such as pollen, nylon-based, polyester-based, urea-based, melamine-based, condensed resin fine particles typified by guanamine-based,
Synthetic resin fine particles such as polyaddition type resin fine particles typified by polyurethane type and epoxy type and polymerization type resin fine particles typified by vinyl type are preferably used.

It should be noted that synthetic resin fine particles are produced by external force when a resin is produced by a method that utilizes the morphological generation associated with the progress of the polycondensation reaction from a solvent such as water, an emulsion polymerization method or a suspension polymerization method. It can also be produced by a treatment after resin formation by a method of controlling the production, a submerged granulation method in a non-solvent, a freeze-drying method, a mechanical granulation method such as a dry or wet granulation method. ..

Among the resin fine particles as described above, 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. Incidentally, these resin fine particles, spheres, flat, Konpeito, snow dharma, wild strawberries, stars, such as amorphous, any shape is known, any of which can be used, when used in combination with spherical particles, The effects of the present invention can be obtained more significantly.

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.

As the inorganic powder, clay, kaolin, calcined kaolin, delaminated kaolin, structural kaolin, aluminum hydroxide, titanium dioxide, barium sulfate, zinc oxide, satin white, talc, silica and the like are commonly used. So-called inorganic pigments used in the coating field are used.

Further, the coating liquid for forming the intermediate layer includes, for example,
Various binders may be added to improve adhesiveness and fluidity, and dyes, pigments, fluorescent dyes for controlling color tone and whiteness, and UV absorption for improving storage stability. Agents, antioxidants and the like may be added. Further, in order to improve the smearability, a dispersant, a wetting agent, an antifoaming agent, etc. may be added, and other antiseptics, antifungal agents, antistatic agents, water resistance agents, crosslinking agents, etc. Addition of various auxiliaries known in the art is also optional.

Examples of the binders include modified starch,
Natural and semi-synthetic polymers such as carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, casein, gelatin, natural rubber; polydienes such as polyvinyl alcohol, isoprene, neoprene, polybutadiene, polybutene, polyisobutylene, polypropylene, polyethylene, etc. Of polyalkenes, vinyl halides, vinyl acetate, styrene, (meth) acrylic acid, (meth) acrylic acid ester, (meth) acrylamide, methyl vinyl ether, and other vinyl polymers and copolymers,
Examples include so-called coating binders such as synthetic polymers such as polyesters, polyurethanes, polyamides, styrene / butadiene-based, methyl methacrylate / butadiene / maleic acid-based synthetic rubber latex, and the like, and are added as necessary. However, it is desirable that the amount used is limited to about 500% by weight or less with respect to the specific vinyl acetate resin which is an essential component.

The intermediate layer may be formed on the support in accordance with a conventional method by using various coating devices used in the general coating field, such as a blade coater and an air knife coater.
It can be formed by using a roll coater, a die coater, a curtain coater, or the like. Further, when the coating amount of the intermediate layer is 0.2 g / m ² or less in dry weight, the desired effect of the present invention cannot be sufficiently obtained, and therefore, it is generally 0.
It is adjusted within the range of about 5 to 50 g / m ² .

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 carried out, for example, by heating or pressurizing with a super calender, gloss calender, cast drum or the like, and at this time, the spherical resin fine particles described above, particularly having an average particle diameter of about 0.2 to 50 μm, are used. If the resin fine particles are used in an amount of about 0.01 to 100 parts by weight, preferably 0.5 to 20 parts by weight, based on 1 part by weight of the specific vinyl acetate resin of the present invention, the effect of the smoothing treatment is obtained. It can be obtained extremely remarkably.

In the image-receiving sheet of the present invention, the image-receiving layer provided on the intermediate layer is not particularly limited, but generally a thermoplastic resin layer having an effective dyeing ability for a sublimable dye is used. It is preferably 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, vinyl acetate; polyester, polyamide, polycarbonate. Condensation polymers such as 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. Inorganic or organic pigments such as powder, and various auxiliaries such as an ultraviolet absorber, an antioxidant, an antistatic agent, a release agent and a lubricant may be added.

The coating amount of the constituents forming the image-receiving layer on the intermediate layer is appropriately adjusted depending on the purpose of use of the image-receiving sheet, but generally it is about ² to 15 g / m ^{2 in} dry weight. Coated. 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 mainly by making cellulose pulp as a main component and adding a paper strengthening agent, a sizing agent, a fixing agent, an inorganic material, an organic filler, etc. Include papers whose surface physical properties are improved by size-pressing oxidized starch, etc., or by providing a precoat layer containing clay and other pigments as a main component, but such as art paper, coated paper, cast coated paper, etc. Paper with excellent smoothness is particularly preferably used.

An image-receiving layer is formed on these supports after the formation of the intermediate layer. If necessary, before or after the formation of the intermediate layer, the adhesiveness, barrier property, smoothness, hiding property, and In order to control smearing suitability and the like, an anchor coat layer may be provided, a thin film substrate may be extruded and laminated, or laminated.

On the image receiving layer, for example, Japanese Patent Laid-Open No. Sho 59 is used.
As disclosed in JP-A-165688 and JP-A-61-27290, a thin heat-resistant release layer containing a silicone 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 handling suitability and printer suitability of the obtained thermal transfer recording image-receiving sheet, for example, a back coat layer is provided for the purpose of preventing curling, controlling slipperiness, and imparting writability, or antistatic on the front surface or back surface. It is also possible to perform various kinds of treatments that are commonly used in the art, such as treatment.

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 can be used by appropriately selecting from various dyes such as oil-soluble dyes.

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.

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 of a thermal printing unit, a thermal head, etc., but also a heat ray of an infrared lamp, a YAG laser, a carbon dioxide gas laser, etc. 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 the present invention is not limited to the examples. Unless otherwise specified, "parts" and "%" in the examples represent "parts by weight" and "% by weight", respectively.

[0033]

【Example】

Example 1 A benzoguanamine resin powder (trade name: Eposter) was added to 100 parts of a 7% aqueous solution of a vinyl acetate resin having a sulfonic acid group (trade name: Gocelan L-0301, polymerization degree 300, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.). MS, spherical, average particle size 2
μm, manufactured by Nippon Shokubai Co., Ltd.) was dispersed and mixed with a stirrer to prepare a coating liquid for the intermediate layer, and commercially available high-quality paper (trade name: TKP-
13, basis weight 85 g / m ² , manufactured by Kanzaki Paper Co., Ltd.) and dried so that the dry weight was 7 g / m ² .

Then, an aqueous polyester resin (trade name:
Bayronal MD-1200, solid content 34%, manufactured by Toyobo Co., Ltd.) was applied on the intermediate layer so as to have a dry weight of 4 g / m ² , dried to form an image receiving layer, and then mirror-finished metal. Smoothing treatment (linear pressure: 200 kg / cm) was performed with a super calendar composed of rolls and elastic rolls.

Saturated polyester resin (trade name:
Byron 200, Toyobo Co., Ltd. 100 parts, amino-modified silicone oil (trade name: KF-393, Shin-Etsu Silicone Co., Ltd.) 1.5 parts and epoxy-modified silicone oil (trade name: X-22-343, Shin-Etsu Silicone Co., Ltd.) Made)
1.5 parts of methyl ethyl ketone / toluene (weight ratio 1
1) with stirring with a mixer to prepare a coating solution by adding, mixing, and dissolving, and 1 g / dry weight on the image-receiving layer obtained above.
After applying m ² and drying, it was heat-cured at 100 ° C. for 2 minutes to obtain an image-receiving sheet for thermal transfer recording.

Comparative Example 1 As a coating liquid for the intermediate layer, a commercially available polyvinyl alcohol (trade name: Gohsenol GL-05, degree of polymerization 500, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) was used instead of the vinyl acetate resin having a sulfonic acid group. An image receiving sheet for thermal transfer recording was obtained in the same manner as in Example 1 except that the coating liquid prepared by using was used.

Comparative Example 2 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 formed.

The following three types of quality comparison tests were carried out on the thus obtained three types of thermal transfer recording image-receiving sheets, and the results are shown in Table 1.

[Quality Comparison Test] A commercially available color material transfer sheet (for Hitachi printer VY-P1: magenta color part) and a coating surface of a thermal transfer recording image receiving sheet are superposed, and a thermal head is used from the back of the color material transfer sheet. Heat is applied (12V, 4 ~
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 the recorded image of each image receiving sheet were evaluated.

[Recording Density] Macbeth Densitometer (RD-91
It was measured in 4). [Image Quality] The image in the highlight part (7 ms) was observed with a 25 times magnifying glass, and dot reproducibility and dot dropout were visually evaluated according to the following evaluation criteria. [Evaluation Criteria] A: No dot dropout and excellent dot reproducibility. B: No dot omission and excellent dot reproducibility. C: There are some missing dots, but dot reproducibility is at a practical level. D: Missing dots are conspicuous and there is a problem in practicality. E: Missing dots and poor reproducibility are not practical.

[0041]

[Table 1]

Example 2 20 parts of a vinyl acetate resin having a sulfonic acid group (trade name: Gocelan L-0302, degree of polymerization: 500, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.), 40 parts of water and 6 of isopropyl alcohol
A commercially available white polyester film having micropores (trade name: W-900E, film thickness: 75 μ)
m, manufactured by Dia foil Co., Ltd.), and the dry weight is 10 g / m ²
It was applied and dried so that

Next, in a mixed solvent consisting of 40 parts of methyl ethyl ketone, 40 parts of toluene, and 20 parts of cyclohexanone, 10 parts of a vinyl chloride / vinyl acetate copolymer (trade name: S-REC A, Sekisui Chemical Co., Ltd.) and a polyester resin (trade name) : Byron 200, manufactured by Toyobo Co., Ltd., 10 parts are dissolved, and further, amino modified silicone oil (trade name: KF-393, Shin-Etsu Chemical Co., Ltd.) 0.3 part, epoxy modified silicone oil (trade name: X-33) -343, manufactured by Shin-Etsu Chemical Co., Ltd.)
0.3 part was added to prepare an image receiving layer coating liquid. This coating solution was applied onto the above-mentioned intermediate layer so as to have a dry weight of 5 g / m ² , dried, and heat-cured at 120 ° C. for 5 minutes to obtain an image-receiving sheet for thermal transfer recording.

Comparative Example 3 An image receiving sheet for thermal transfer recording was obtained in the same manner as in Example 2 except that the intermediate layer was not provided.

With respect to the thus obtained two types of thermal transfer recording image-receiving sheets, the same quality comparison test as in Example 1 was conducted, and Table 2 shows the results.

[0046]

[Table 2]

[0047]

As is apparent from the results of the table, the image-receiving sheets for thermal transfer recording obtained in the examples of the present invention have excellent recording sensitivity, and only extremely clear recorded images with high color density can be obtained. In addition, the image quality was excellent.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shinsuke Irai 4-3-1, Jokoji Temple, Amagasaki City, Hyogo Prefecture Kanzaki Paper Co., Ltd. Kanzaki Mill

Claims (1)

[Claims] 1. An image-receiving sheet for thermal transfer recording comprising an image-receiving layer for receiving a transfer image from a color material transfer sheet on a support, wherein a sulfonic acid group is provided between the support and the image-receiving layer of the image-receiving sheet. An image-receiving sheet for thermal transfer recording, comprising an intermediate layer containing the vinyl acetate resin.