JPH06270557A - Thermal transfer image receiving sheet - Google Patents

Abstract

PURPOSE:To prevent density irregularity and to enhance sensitivity, in the sheet for a color hard copy, by providing an intermediate layer containing fine particles of a rubber elastomer and hollow particles in a predetermined wt. ratio between a support and an image receiving layer. CONSTITUTION:An intermediate layer containing fine particles of a rubber elastomer such as silicone rubber and thermally expansible hollow particles or capsule like hollow polymer particles is provided between a support and an image receiving layer receiving the dye transferred from a thermal transfer medium at a time of melting or sublimation under heating. At this time, a wt. ratio of rubber elastomer fine particles/hollow particles is set to 10-80/90-20. The particle size of the rubber elastomer particles is pref. about 0.1-10mum and, when the particle size is too small, no cushioning properties are obtained. The thermally expansible hollow particles are formed from a vinylidene chloride/ acrylonitrile copolymer and thermally expansible gas such as propane is contained in the particles. The capsule like hollow polymer particles are formed from a styrene/acrylate resin and contain water therein.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer image-receiving sheet, and more particularly to a high-sensitivity thermal transfer image-receiving sheet having no density unevenness.

[0002]

2. Description of the Related Art In recent years, as a means for color hard copy, an apparatus using a thermal transfer recording system has been widely used because of its advantages such as light weight, compact size, no noise, excellent operability and maintainability. . This thermal transfer recording system is roughly classified into two types, which are a heat melting type and a heat transfer type or a sublimation type. In particular, the latter is excellent in reproducibility of multicolor gradation images and is printed by using a sublimation type thermal transfer type printer. The principle of such a sublimation type thermal transfer type printer is that an image is converted into an electric signal, and this electric signal is further converted into a heat signal by a thermal head, and a thermal transfer medium coated with a heat transferable dye (hereinafter, An ink donor sheet) is heated, and dye is transferred from the ink donor sheet to the image receiving layer of the thermal transfer image receiving sheet by sublimation or diffusion in the medium, thereby recording information.

[0003]

In particular, in recent years, from the viewpoint of increasing the printing speed, it has been required to improve the sensitivity, that is, the transfer density, and such high sensitivity is disclosed in, for example, Japanese Patent Laid-Open No. 62-62. -87390, JP-A-03-266691
Described in Japanese Patent Publication, polypropylene having a void structure, polyester produced by a biaxial stretching method,
It is known that synthetic resin films such as polyethylene terephthalate and synthetic paper are effective because they have excellent cushioning properties and heat insulating properties. However, since such a synthetic film or synthetic paper is inferior in heat resistance, for example, a heat shrinkage occurs or a surface shrinkage occurs due to an applied energy heat in a drying step or printing in the case of laminating a support having a multilayer structure. There were problems such as unevenness. The voids of such synthetic resin film or synthetic paper are generally several to several tens of μm in thickness and several to several tens of μm in length, but the platen pressure is applied to the thermal transfer image receiving sheet during printing. When it was compressed due to cracking, minute density unevenness due to the density unevenness of the void structure occurred. Furthermore, curl suitability,
It was difficult to provide an inexpensive image-receiving sheet with a support such as paper, resin-coated paper, PET film or the like, which is laminated in consideration of paper feeding and handling in a printer.

Therefore, in JP-A-62-151393 and JP-A-63-98494, an elastic layer is provided between the support and the image-receiving layer, which is inexpensive and has no density unevenness or white spots. It is shown that an image receiving sheet having a high sensitivity can be obtained as compared with an image receiving sheet in which an image receiving layer is directly provided on plain paper or coated paper. However, simply providing an elastic film as the intermediate layer lacks heat insulating properties and cannot achieve the high sensitivity required in recent years.

Therefore, the inventors of the present invention invented an image-receiving sheet in which an intermediate layer containing polymer microspheres is provided on a support for the purpose of improving cushioning properties and heat insulating properties, and applied for a patent ( JP-A-2-248289 and JP-A-2-286290). The purpose of the present invention is to
It is another object of the present invention to provide an image-receiving sheet for thermal transfer, which is improved from the invention of the prior application and has high sensitivity without uneven density even when inexpensive plain paper or coated paper is used as a substrate.

[0006]

Means for Solving the Problems As a result of earnest studies on such problems, the present inventors provided an intermediate layer containing rubber elastic fine particles and hollow particles as main components between a support and an image receiving layer. We achieved higher sensitivity and invented.

The rubber elastic fine particles are for the purpose of imparting cushioning property to the image receiving sheet, and the hollow particles are for imparting heat insulating property to the image receiving sheet, and an intermediate layer containing both components. Was excellent in cushioning and heat insulating properties such as synthetic resin film and synthetic paper.

Accordingly, the thermal transfer image-receiving sheet of the present invention is
In the image-receiving sheet for thermal transfer provided on the surface of the support, an image-receiving layer for receiving a dye that migrates from the thermal transfer medium by heat melting or sublimation during heating, between the support and the image-receiving layer,
An intermediate layer containing rubber elastic fine particles and hollow particles as main components is provided.

The rubber transfer fine particle / hollow particle weight ratio contained in the intermediate layer is 10 to 80/90 to 20, which is an image-receiving sheet for thermal transfer.

The present invention will be described in detail below. The rubber elastic fine particles in the present invention are partially low-crosslinked in a three-dimensional network and exhibit deformation or limited fluidity due to the application of stress. Suitable rubber elastic particles in the present invention include, for example, silicone rubber, butadiene rubber, styrene / butadiene rubber, high styrene / butadiene rubber, butyl rubber, fluorine rubber, nitrile rubber, chloroprene rubber, acrylic rubber, urethane rubber, isoprene. Rubber, natural rubber obtained by coagulating and drying emulsion obtained by damaging bark of rubber tree, chlorosulfonated polyethylene, chlorinated polyethylene, chlorinated butyl rubber, polysulfide rubber, epichlorohydrin rubber, propylene oxide rubber, ethylene-acetic acid These are fine particles made of vinyl rubber or the like alone or in combination of two or more kinds.

The particle size suitable for the rubber elastic fine particles in the present invention is in the range of 0.1 to 10 μm, and more preferably in the range of 0.5 to 7 μm. If the particle size is too small, sufficient cushioning properties will not be obtained, and if it is too large, the surface smoothness will deteriorate significantly. Therefore, even if the rubber elastic particles have elasticity, the adhesion between the thermal head and the image receiving sheet Sensitivity cannot be compensated for because it cannot be compensated for.

The hollow particles used in the present invention include thermally expandable hollow particles and capsule-shaped hollow polymers.
The thermally expandable hollow particles are hollow particles having a thermoplastic material such as vinylidene chloride-acrylonitrile copolymer as a wall material, and a material containing a thermally expandable gas such as propane, n-butane and isobutane inside the particles. Is. Further, the capsule-shaped hollow polymer is a polymer having a resin such as styrene-acryl as a wall material and having water inside, and the water is evaporated into a hollow particle when dried. Hollow particles as described above,
Generally, the particle size is about 0.1 to 100 μm,
The particle size of the hollow particles used in the present invention is 0.7.
It is preferably from 10 to 10 μm, more preferably from 1 to 5 μm. If it is less than 0.7 μm, a sufficient heat insulating effect cannot be obtained as hollow particles, and if it exceeds 10 μm, the smoothness is significantly deteriorated.

The weight ratio of the rubber elastic fine particles / hollow particles contained in the intermediate layer in the present invention is from 10 to 80/90.
20 and more preferably 20 to 60/80 to 40. If the content of the rubber elastic fine particles is too small, the cushioning property imparted to the thermal transfer image-receiving sheet will be insufficient, and high sensitivity cannot be achieved. Further, if the content of the hollow particles is too small, the heat insulating property imparted to the thermal transfer image-receiving sheet is insufficient,
After all, high sensitivity cannot be achieved.

To form the intermediate layer in the present invention, the above-mentioned rubber elastic body and hollow particles are mixed with the binder resin described below and used. As the binder resin, styrene / butadiene / acrylic copolymer, polyurethane,
Resins such as acrylic, vinyl chloride, vinyl acetate, vinyl chloride / vinyl acetate copolymer, polyvinyl alcohol, polyvinyl butyral, alkyd, polyester and starch can be used alone or in combination of two or more.

The compounding ratio of the binder resin to the rubber elastic fine particles and hollow particles contained in the intermediate layer in the present invention is 2 to 50% by weight. If the amount of the binder resin is too small, the film strength will be significantly reduced, which is not preferable.
On the other hand, if the amount of the binder resin is too large, the cushioning property and the heat insulating property imparted to the thermal transfer image-receiving sheet will be insufficient, and high sensitivity cannot be achieved.

Further, if necessary, dyes, pigments, wetting agents,
The intermediate layer may contain additives such as a defoaming agent, a dispersant, an antistatic agent, a fluorescent brightening agent, an ultraviolet absorber and a light stabilizer.

Examples of the method for providing the intermediate layer of the present invention include an air knife coater, a curtain coater, a die coater, a blade coater, a gate roll coater, a bar coater, a rod coater, a roll coater, a bill blade coater and a short dwell blade coater. Can be used.

The coating amount of the intermediate layer of the present invention is preferably 1 to 70 g / m ² , more preferably 5 in terms of dry coating amount.
Is in the range of up to 50 g / m ² .

As the support for use in the thermal transfer image-receiving sheet of the present invention, the same substrate as that used in the conventional thermal transfer image-receiving sheet can be used as it is, and other materials can be used without any particular limitation. Specific examples of preferable supports include high-quality paper, coated paper, art paper, cast-coated paper and polyolefin-coated paper. The thickness of this support can be appropriately changed depending on the material so that the strength, heat resistance and the like are appropriate, but the thickness is 5 to 300 μm.

On the support of the present invention, an image-receiving layer having a dyeing property to a dye which is melted or sublimated by heat and migrates is provided to form a thermal transfer image-receiving sheet, which constitutes the image-receiving layer. As the dye-dyeing binder resin, any binder resin having a strong interaction with the dye and capable of stably diffusing the dye into the resin can be preferably used. For example, those having an ester bond include polyester resin, polyacrylic ester resin, polycarbonate resin, polyvinyl acetate resin, styrene acrylate resin, etc., and those having a urethane bond include polyurethane resin; those having an amide bond. Polyamide resin (nylon); urea resin having a urea bond; urea resin having a high polarity, and polycaprolactone resin, polystyrene resin, polyvinyl chloride, polyacrylonitrile resin, etc. Can be used or
It can also be used as a copolymer containing at least one of the constitutional units of the above resin as a main component, for example, vinyl chloride-vinyl acetate copolymer, styrene-butadiene copolymer, and the like. They can be used alone or in combination of two or more. The above resin may be dissolved in water or an organic solvent and applied on the intermediate layer, or it may be emulsified in an aqueous solution and applied as an emulsion. If necessary, an easy adhesion treatment may be applied to the intermediate layer. It is also possible to improve the adhesion to the image receiving layer.

As a method for making the intermediate layer easily adhesive, there are a method of modifying the intermediate layer by corona treatment, a plasma treatment, etc., or a method of applying a resin having good adhesiveness to both the intermediate layer and the image receiving layer. is there. As such a resin, any resin having good adhesiveness to both layers can be preferably used, but, for example, acrylic resin, vinyl chloride resin, vinyl acetate resin, urethane resin, styrene butadiene resin,
Or the copolymer etc. can be illustrated. The coating amount of the above image receiving layer is 0.5 to 30.0 g / m 2 in terms of dry solid content.
A range of ² is preferred.

In the present invention, a releasing agent may be added to the image receiving layer for the purpose of preventing blocking. Specific examples of such a release agent include waxes such as higher fatty acid or ester thereof, amide or metal salt thereof, shellac wax, montan wax, carnauba wax, polyethylene wax and Teflon powder; fluorine-based and phosphoric ester-based waxes. Surfactants; silicone oil and the like can be mentioned. Further, as the silicone oil, modified silicone oil such as amino-modified silicone, epoxy-modified silicone, alkyd-modified silicone, polyester-modified silicone and the like can be used. If necessary, a curable silicone compound can be used as the silicone compound. Examples of the curable silicone compound include a reaction curable type, an ionizing radiation curable type, and a catalyst curable type.

Further, if necessary, dyes, pigments, wetting agents,
The image receiving layer may contain additives such as a defoaming agent, a dispersant, an antistatic agent, a fluorescent brightening agent, an ultraviolet absorber and a light stabilizer. In particular, with respect to the pigment, inorganic particles represented by silica, alumina, titanium oxide, calcium carbonate, kaolin, clay, zinc oxide, barium sulfate and the like can be added.

Further, a backing layer containing an inorganic fine powder is provided on the side of the support opposite to the image receiving layer in order to provide roll slipperiness during transfer and writing on the back side, or for the purpose of preventing static charge. Then, an antistatic agent can be added to the backing layer. When an adhesive resin is mixed in the backing layer, the adhesive resin and an antistatic agent are mixed and bleeding on the resin surface,
As a result, it can be provided on the resin layer. Examples of the antistatic agent include surfactants such as cationic surfactants (quaternary ammonium salts, polyamine derivatives, etc.), anionic surfactants (alkyl phosphates, etc.), zwitterionic surfactants, or nonionics. Type surfactants and the like.

[0025]

The present invention relates to an image-receiving sheet for thermal transfer provided with an image-receiving layer for receiving a dye which migrates from a thermal transfer medium by heat melting or sublimation upon heating, and rubber elastic fine particles are provided between the support and the image-receiving layer. By providing an intermediate layer containing hollow particles as a main component, the thermal transfer image-receiving sheet is provided with cushioning properties and heat insulation properties, so that a high-sensitivity thermal transfer image-receiving sheet can be obtained without uneven density.

[0026]

EXAMPLES Next, the present invention will be described in more detail by way of examples, but the contents of the present invention are not limited to these. In addition, "part" and "%" shown in the examples
Indicates parts by weight and% by weight. The ink donor sheet for evaluation was prepared as follows.

Heat-treated film having a film thickness of 5 μm 2
The following heat resistant slipping layer coating liquid was prepared on an axially stretched polyester film, and the dry coating amount was 0.5 g / m with a wire bar.
^{It was} applied so as to have a viscosity of ² , and was irradiated with ultraviolet rays by a high pressure mercury lamp of 140 W / cm ² to be cured. [Preparation of coating liquid for heat resistant slipping layer] TMPTA (Daiichi Kogyo Seiyaku Co., Ltd.) 10 parts Lipoxy SP1509 (Showa High Polymer) 20 parts Trefil E500 (Toray, silicone fine particles) 9 parts KF-393 (Shin-Etsu silicone, amino-modified silicone oil) 0.3 parts Coronate L (Japan polyurethane, isocyanate) 0.3 parts Darocur1173 (Merck, initiator) 0.4 parts Ethyl acetate 40 parts Isopropyl alcohol 20 parts

Further, a sublimation dye solution having the following composition was prepared on the other surface of the heat resistant slipping layer, pulverized with a ball mill for 2 days, and dried with a wire bar to give a dry coating amount of 1.5 g / m ^2. Thus, a donor sheet was prepared. [Preparation of Sublimation Dye Liquid] Kayaset Blue 906 (Nippon Kayaku, sublimation dye) 10 parts Ethyl Semellose 10 parts Syloid 244 (Fuji Davisson silica gel) 10 parts Isopropyl alcohol 30 parts

[0029] coated paper of Example 1 basis weight 140 g / m ^2, an intermediate layer coating solution having the following composition was prepared, was applied by an air knife coater so that the 20 g / m ² on a dry solids, of the following An image-receiving layer coating solution having the composition was prepared and coated with an air knife coater so that the dry coating amount was 7 g / m ² . The thermal transfer image-receiving sheet thus obtained was used as the thermal transfer image-receiving sheet of Example 1. [Preparation of coating liquid for intermediate layer] Hollow particles (HP-91: Rohm & Haas, average particle size 1 µm) 97 parts Rubber elastic fine particles (DX33-411: Toray Dow Corning Silicone, average particle size 3 µm) 3 parts Styrene -Butadiene latex (L-1876: Asahi Kasei Latex) 10 parts [Preparation of coating liquid for image-receiving layer] Polyester emulsion (Vylonal MD-1220: Toyobo) 60 parts Polyerylene emulsion (Hydrin G-314: Chukyo Yushi) 15 parts Inorganic fine particles As colloidal silica (Snowtex O: Nissan Kagaku) 25 parts Surfactant 5 parts

Examples 2 to 9 A thermal transfer image-receiving sheet was prepared in the same manner as in Example 1 except that the compounding ratio of the rubber elastic fine particles and the hollow particles was changed to the compounding ratio shown in Table 1. The image receiving sheet for thermal transfer of No. 9 was used.

The base paper of Example 10 basis weight 110g / m ^2, a laminate paper obtained by polyethylene-coated front and back 10 g / m ^2, an intermediate layer coating solution having the following composition was prepared, dry coating amount becomes 30 g / m ² An image receiving sheet for thermal transfer of Example 10 was obtained in the same manner as in Example 1 except that the coating was performed with an air knife coater. [Preparation of coating liquid for intermediate layer] Hollow particles (Grostell 1161-EX: Mitsui Toatsu, average particle size 0.9 μm) 60 parts Rubber elastic fine particles (Trefil E-730S: Toray Dow Corning Silicone, average particles) Diameter 1.5 μm) 35 parts Urethane emulsion (Hydran HW-301: Dainippon Ink and Chemicals) 3 parts Polyvinyl alcohol (PVA-117: Kuraray) 2 parts

[0032] paper cast-coated of Example 11 basis weight 140 g / m ^2, to prepare an intermediate layer coating solution having the following composition, except that dry coating amount was applied by an air knife coater so that the 15 g / m ² is An image receiving sheet for thermal transfer of Example 11 was obtained in the same manner as in Example 1. [Preparation of coating liquid for intermediate layer] Hollow particles (Microsphere MB927: Hohne, average particle size 7 μm) 35 parts Rubber elastic fine particles (Trefil E-500: Toray Dow Corning Silicone, average particle size 3 μm) 55 parts Polyester resin (S-114S: Takamatsu fats and oils) 10 parts

Comparative Example 1 An image receiving sheet for thermal transfer was prepared in the same manner as in Example 1 except that the compounding ratio of the rubber elastic fine particles and the hollow particles was changed to the compounding ratio shown in Table 1. The image receiving sheet was used.

Comparative Example 2 An image-receiving sheet for thermal transfer was prepared in the same manner as in Example 1 except that the compounding ratio of the rubber elastic fine particles and the hollow particles was changed to the compounding ratio shown in Table 1. The image receiving sheet was used.

Comparative Example 3 The following coating solution for the intermediate layer was prepared, and the coating amount was 6 g / m ² on a dry basis except that a rod coater was used.
In the same manner as in Example 1, an image receiving sheet for thermal transfer of Comparative Example 3 was obtained. [Preparation of coating liquid for intermediate layer] Styrene / butadiene copolymer (Polylac: Mitsui Toatsu Chemical) 50 parts Water 50 parts

Comparative Example 4 The following intermediate layer coating solution was prepared, except that a dry coat weight was 6 g / m ² using a rod coater.
In the same manner as in Example 1, an image receiving sheet for thermal transfer of Comparative Example 4 was obtained. [Preparation of coating liquid for intermediate layer] Nitrile rubber latex (Nippole 1561: Zeon Corporation) 50 parts Water 50 parts

Comparative Example 5 An adhesive having the following composition was prepared on a coated paper having a basis weight of 90 g / m ² , coated with a gravure coater so that the dry coating amount was 3.0 g / m ^2, and biaxially stretched. Polypropylene synthetic paper (Pyrene film, Toyopearl SS 50 μm: Toyobo) was laminated and then cured at 50 ° C. Further, synthetic paper was stuck on the other surface in the same manner to obtain a double-sided synthetic paper laminate support. The dry coating amount of the image-receiving layer described in Example 1 was 7.0 g / m ² on this laminated support.
Was applied by an air knife coater to obtain a thermal transfer image-receiving sheet of Comparative Example 5. [Adhesive preparation] Polyester polyol (Takelac A-606: Takeda Yakuhin) 90 parts Polyurethane polyisocyanate (Takenate A-12: Takeda Yakuhin) 10 parts

Comparative Example 6 A thermal transfer image-receiving sheet was prepared in the same manner as in Comparative Example 5 except that the biaxially oriented polypropylene synthetic paper was changed to YUPO FPG60: Oji Okaka Synthetic. did.

[0039]

[Table 1]

[Evaluation Method] The image-receiving sheet for thermal transfer thus obtained was allowed to stand at 45 ° C. for 3 days, then an ink donor sheet was overlaid thereon, and a sublimation type thermal transfer printer S3600 manufactured by Mitsubishi Electric Corporation was used.
It was printed at -30. This print density is Macbeth RD-91.
9 Measured with an optical densitometer. Concerning the density unevenness, those having no density unevenness were evaluated as ⊚, those having slight density unevenness were evaluated as ◯, those having density unevenness as Δ, and those having significant density unevenness as x. It was shown to.

[0041]

[Table 2]

[Evaluation] Examples 1 to 11 are comparative examples 1 to 6.
Compared with, the transfer density was high and the uneven density was also improved. In particular, in Examples 3 to 6 and 10 and 11, since the cushioning property of the rubber elastic fine particles and the heat insulating property of the hollow particles to the image receiving sheet for thermal transfer were excellent, the transfer density was very high and there was no density unevenness. . In Comparative Examples 1 and 2, since the rubber elastic fine particles or hollow particles were not contained in the intermediate layer, the transfer density was inferior and uneven density was observed. In Comparative Examples 3 and 4, hollow particles and rubber elastic fine particles were not contained in the intermediate layer, and only the intermediate layer made of rubber latex was provided. Therefore, the transfer density was low and remarkable density unevenness occurred. . In Comparative Examples 5 and 6, since biaxially stretched synthetic paper having a void structure was used, although the transfer density was high, density unevenness occurred.

[0043]

INDUSTRIAL APPLICABILITY The present invention provides a cushion for a thermal transfer image-receiving sheet by providing an intermediate layer containing rubber elastic fine particles and hollow particles as main components between the support and the image-receiving layer of the thermal transfer image-receiving sheet. And heat insulation can be added,
A highly sensitive image-receiving sheet for thermal transfer having no density unevenness can be obtained.

Claims (2)

[Claims] 1. A thermal transfer image-receiving sheet having an image-receiving layer on the surface of a support, the image-receiving layer receiving a dye that migrates from a thermal transfer medium by heat fusion or sublimation during heating, between the support and the image-receiving layer. An image receiving sheet for thermal transfer, comprising an intermediate layer containing rubber elastic fine particles and hollow particles as main components. 2. Elastic rubber fine particles contained in the intermediate layer /
The thermal transfer image-receiving sheet according to claim 1, wherein the weight ratio of the hollow particles is 10 to 80/90 to 20.