JP2967992B2 - Sublimation type thermal transfer recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sublimation type thermal transfer recording medium.

2. Description of the Related Art In recent years, the demand for full-color printers has been increasing year by year, and the recording methods of the full-color printer include an electrophotographic method, an ink jet method, and a thermal transfer method. Among them, thermal transfer is easy due to easy maintenance and no noise. Many methods are used.

This thermal transfer consists of a solidified color ink sheet and an image receiving paper, and heat transfer or sublimation transfer of the ink to the receiving paper by thermal energy controlled by an electric signal of a laser, a thermal head, etc., to form an image. This is a recording method to be performed.

The thermal transfer recording system is roughly classified into the heat melting transfer type and the sublimation transfer type. In particular, in the latter case, the sublimation dye sublimates in a monomolecular state corresponding to heat energy from a thermal head or the like in principle. It has the advantage that halftones can be easily obtained and the gradation can be controlled arbitrarily, and is considered to be the most suitable method for a full-color printer.

However, in this sublimation transfer recording method, a color ink sheet is used as a recording supply, and heat recording is selectively performed according to an image signal. In order to obtain one full-color image, yellow, magenta, cyan, (black) (1) Ink sheet is used one by one, and even if there is an unused portion, it is discarded.

Therefore, focusing on this drawback, the ink sheet and the image receiving body are moved at a constant speed in order to improve the drawback by using the ink sheet a number of times, and the constant speed mode method used repeatedly and the running speed of the ink sheet are used. An N-fold mode method has been proposed in which the overlap of the first use portion and the second use portion of the color material layer is gradually shifted and used later than that of the image receiving body.

However, in the sublimation-type thermal transfer recording method, the sublimation and evaporation reactions are basically zero-order reactions, and the number of printings is reduced even though the amount of dye that can withstand many uses is included in the ink layer. As the number of prints increases, the transfer density particularly in the high image density portion rapidly decreases, so that printing many times cannot be substantially performed.

In view of this, the present inventors have proposed in Japanese Patent Application No. 63-62866 a sublimation type thermal transfer recording medium having a laminated structure, and referred to as “a dye supply layer having a dye releasing ability between a dye supply layer and a dye transfer contributing layer. > Dye Transfer Contribution Layer "improved density reduction in multiple recordings.

On the other hand, with the improvement of the quality of recording many times, a defect attributed to static electricity has become conspicuous. For example, dust is sucked by electrostatic attraction caused by running or friction of the sheet, and the recording is lost due to the attachment of dust between the thermal transfer sheet and the paper receiving sheet or between the thermal head and the thermal transfer sheet. Non-recording), damage to the elements of the thermal head, sagging of each sheet, poor running, and the like. In particular, the multiple-time method as in the present invention is a more serious problem.

An object of the present invention is to provide a sublimation-type thermal transfer that does not cause a rapid decrease in transfer density even when the number of prints is increased, eliminates the above-mentioned drawbacks caused by electrostatic attraction, runs smoothly, and has little recording loss or unevenness. It is intended to provide a recording medium.

The present invention provides a sublimation-type thermal transfer recording medium comprising a substrate and a dye supply layer and a dye transfer contributing layer each having a sublimable dye dispersed in an organic binder in order from the substrate side. A sublimation type thermal transfer recording medium characterized in that an antistatic layer made of a resin containing an antistatic agent and having a surface resistivity of 1 × 10 ¹⁰ Ω or less is thinly laminated on the dye transfer contributing layer.

The sublimation type thermal transfer recording medium of the present invention has a configuration as shown in FIG. Here, 1 indicates a substrate of the recording medium,
Reference numeral 2 denotes an ink layer composed of a dye supply layer 4 and a dye transfer contributing layer 5, and reference numeral 3 denotes an antistatic layer. The image receiving body is provided with an image receiving layer 7 provided on a base 8.

The antistatic layer is provided for facilitating the release of the charge generated on the heat transfer sheet due to the charging during the handling of the heat transfer sheet.
It may be formed using any material, but is usually formed using a mixture obtained by kneading what is called an antistatic agent into a resin.

Examples of the antistatic agent include cationic surfactants (for example, quaternary ammonium salts, polyamine derivatives, etc.), anionic surfactants (for example, alkyl phosphate, etc.), and amphoteric surfactants (for example, betaine-type surfactants). Or nonionic surfactants (eg, fatty acid esters), and polysiloxane-based surfactants. In connection with the above antistatic agent, amphoteric surfactants or cationic water-soluble acrylic resins or water-soluble polystyrene resins, etc., are coated alone without a binder, and the coating amount when dried is 0.1 to 2 g / m ² approximately of the coating can be an antistatic layer by the formation, the water-soluble resin is also contacted with an antistatic layer by winding or stacking a color material layer of the thermal transfer layer (at a high temperature ) Is not preferred because it does not affect the dyestuff.

On the other hand, inorganic fine powders having excellent electron conductivity can also be mentioned, for example, doping fine powders such as titanium oxide or zinc oxide (mixing impurities with titanium oxide or zinc oxide and baking them to form a crystal lattice of titanium oxide or zinc oxide). (A process of disturbing the semiconductor to make it semiconductive) or a fine powder of tin oxide or the like can be used.

The above antistatic agent is used by dissolving or dispersing it in an organic solvent in which a resin to be a binder is dissolved.

The resin to be a binder is (a) a thermosetting resin,
For example, a thermosetting polyacrylate resin, a polyurethane resin, or a resin selected from (b) a thermoplastic resin such as a polyvinyl chloride resin, a polyvinyl butyral resin, and a polyester resin are preferable.

The prepared conductive paint is generally coated by a usual coating method, for example, a blade coater, a gravure coater, or the like, or may be formed by spray coating.

The thickness of the antistatic layer is 0.1 to 3 μm, preferably 0.1 to 1 μm.
The ratio between the binder and the antistatic agent is determined so that the surface resistivity of the antistatic layer after coating and drying (after curing in some cases) is 1 × 10 ¹⁰ Ω or less. The amphoteric or cationic water-soluble acrylic resin may be used as an alcohol solution, added as an antistatic agent to the binder at a solid content of 5 to 30% by weight, and formed into a paint.

If necessary, the antistatic layer may contain a releasing agent or a filler or a dye used in the lower layer.

The dye supply layer and the dye transfer contributing layer are each formed as a single layer on the substrate with the same amount of adhesion in each of the formulations,
When each of them is overlaid on a separate image receiving layer and the same thermal energy is applied to both, the amount of dye transferred to each image receiving layer is in the relationship of dye supply layer> dye transfer contributing layer.

The thermal transfer may be performed by a thermal head. Alternatively, the support layer and / or the ink layer may be adjusted to generate Joule heat by energization, and may be performed by energization transfer.

Alternatively, a laser transfer method can be used by selecting a material that absorbs laser light and generates heat as the support.

According to the knowledge of the present invention, the diffusion of the dye in the ink layer is Fick's law, that is, the amount of the dye dn that has passed through the cross-sectional area q at the dt time is represented by the dye concentration gradient dc in the diffusion direction.
Assuming that / dx is the average diffusion coefficient of each part in the ink layer when heat is applied, the relationship of dn = − (dc / dx) qdt is applied.

Therefore, as means for facilitating the diffusion and supply of the sublimable dye from the dye supply layer to the transfer contributing layer, there are: I. a relation of the dye supply layer> the transfer contributing layer with respect to the dye concentration, and / or II. There is a means for making the relationship of the dye supply layer> the transfer contributing layer related to the diffusion coefficient in the layer. Further, as a specific method of operating the diffusion coefficient with respect to the above II, for example, Toyoko Sakai et al.
0, No. 12 (1974); Norihiko Kuroki, “Dyeing Theory Chemistry” published by Maki Shoten, p.503-; introduced in the 1st Non-impact Printing Technology Symposium, 3-5. With reference to these, specific methods for realizing the above-mentioned means II include, for example, (1) Since the diffusion coefficient is affected by the energy suppression effect on dye diffusion due to hydrogen bonding between the dye and the organic binder, etc. A method of using an organic polymer material having a large number of proton-supplying groups or proton-accepting groups which are easily hydrogen-bonded to a sublimable dye as a binder of the transfer-contributing layer. (2) The diffusion coefficient is determined by dispersing the dye. Since the organic binder has a glass transition or softening temperature dependency, the diffusion coefficient is higher when the glass transition or softening temperature is lower than the temperature rise characteristics of the layer during printing in this process, and therefore, the organic binder in the dye supply layer is higher. (3) using a substance having a lower glass transition temperature or a lower softening temperature than that of the transfer contributing layer as a binder, (3) having a compatibility with at least one organic binder in the dye supply layer, and A method in which a plasticizer which is incompatible with all the organic binders in the layer is contained in the dye supply layer; (4) a method in which the above methods (1), (2) and (3) are appropriately combined. There are methods and the like, but it is needless to say that the method is not limited to these methods as long as the above relationship of the diffusion coefficient is satisfied.

In designing the material formulation of the dye supply layer and the transfer contributing layer in the present invention, the above-mentioned I and / or II are useful means, and a simple method for confirming whether or not the intended improvement is realized by these effects. As a simple method, when the same amount of coating is formed as a single layer on a substrate in each of the prescriptions of the dye supply layer and the transfer contributing layer, each is superimposed on a separate image receiving layer, and when a certain sublimation temperature is applied, sublimation occurs. There is a method of selecting each layer such that the transfer amount satisfies the relationship of the dye supply layer> the transfer contribution layer.

Next, the thickness of the transfer contributing layer is generally 0.05 to 5 μm,
Preferably, it is 0.1 to 2 μm. The thickness of the dye supply layer is generally 0.1 to 20 μm, preferably 0.5 to 10 μm.

Known sublimable dyes, binders and the like used in the transfer contributing layer and the dye supply layer of the present invention can be used.

The sublimable dye is a dye that sublimates or vaporizes at 60 ° C. or higher, and may be any of those mainly used in thermal transfer printing such as disperse dyes and oil-soluble dyes.For example, CI Disperse Yellow 1,3,8, CI Disperse Blue 3,14,19, such as 9,16,41,54,60,77,116, CI Disperse Red 1,4,6,11,15,17,55,59,60,73,83 , 26,56,60,64,7
2,99,108, CI Solvent Yellow 77,116, etc.
CI Solvent Blue 23, 25, 27 and CI Solvent Blue 36, 83, 105 and the like can be mentioned. One of these dyes can be used, but a mixture of several dyes can be used.

Thermoplastic or thermosetting resin is used for the binder used for the dye transfer contributing layer and the dye supply layer. Among the resins having a relatively high glass transition point or high softening property, for example, vinyl chloride resin , Vinyl acetate resin, polyamide, polyethylene, polycarbonate, polystyrene, polypropylene, acrylic resin, phenol resin,
Polyester, polyurethane, epoxy resin, silicone resin, fluorine resin, butyral resin, melamine resin,
Examples include natural rubber, synthetic rubber, polyvinyl alcohol, and cellulose resin. These resins can be used singly, but a mixture of several resins or a copolymer may be used.

Further, when making a difference with respect to the glass transition or softening temperature between the dye transfer contributing layer and the dye supply layer, a resin or a natural or synthetic rubber having a glass transition temperature of 0 ° C. or less, or a softening temperature of 60 ° C. or less is preferable. Include syndiotactic 1,2-polybutadiene (commercially available as JSR RB810,820,830 Nippon Synthetic Rubber); olefin copolymers and terpolymers containing acids or non-acidic acids (commercially available as Dexon XEA-7, Dexon Chemical); Ethylene-vinyl acetate copolymer (400 & 400A, 405,43 as a commercial product)
0, Allied Fibers &Plastics; P-3307
(EV150), P-2807 (EV250), DuPont Mitsui Polychemicals); low molecular weight polyolefin polyols and their derivatives (Polytail H, HE Mitsubishi Kasei Kogyo as commercial products); brominated epoxy resin (YDB-340,400,500,600 Toto Kagaku) Novolak type epoxy resin (YDCN-701,702,70)
3 Toto Chemical); Thermoplastic acrylic solution (Tynalnal LR1075,1080,1081,1082,1063,1079 Mitsubishi Rayon); Thermoplastic acrylic emulsion (LX-400, LX-45)
0, Mitsubishi Rayon); polyethylene oxide (Alcox E-30,45, Alcox R-150,400,1000 Meisei Chemical); caprolactone polyol (Placcel H-1,
And the like. In particular, polyethylene oxide and polycaprolactone polyol are practically useful, and the above-mentioned thermoplastic or thermosetting resin is mixed with one or more of the above-described one or more kinds. It is preferred to use it in form.

The dye concentration of the transfer contributing layer is usually 5 to 80%, preferably,
It is about 10-60%.

The dye concentration of the dye supply layer is preferably from 5 to 80%. However, when a dye concentration gradient is provided between the dye transfer contribution layer and the dye supply layer, the dye concentration is 1.1 to 1.1%. ５5 times, preferably 1.5 to 3 times.

In order to stably supply the dye for a long time and maintain good printing characteristics, the dye supply layer preferably contains at least an undissolved particulate sublimable dye. Here, the undissolved particulate dye means a dye that cannot be completely dissolved in the organic binder after application and drying of the ink (organic binder + sublimable dye + solvent) at the time of forming the ink layer, and precipitates as particles. However, the presence of the undissolved particulate dye differs depending on the solvent even with the same binder and dye. The presence or absence of the undissolved particulate dye can be easily identified by an electron microscope after forming the dye supply layer. The particle size of the undissolved particulate dye varies depending on the layer thickness of the dye supply layer,
It is from 01 μm to 20 μm, preferably from 1.0 μm to 5 μm.

Further, the dye state in the dye transfer contributing layer is that it is dispersed in a monomolecular state which actually contributes to the transfer, preventing the occurrence of uneven transfer density and the dye between the dye supply layer and the dye transfer contributing layer. It is desirable to keep the concentration gradient stable.

As the base sheet, a film such as a condenser paper, a polyester film, a polystyrene film, a polysulfone film, a polyimide film, or a polyamide film is used. If necessary, a conventional adhesive layer may be interposed between the base sheet and the dye supply layer. A conventional heat-resistant lubricating layer may be provided on the back surface of the base sheet, if necessary.

From the dye supply layer to the dye transfer contributing layer or the surface of the thermal transfer body during non-recording (during storage) without hindering the supply of the sublimable dye from the dye supply layer to the dye transfer contributing layer in the thermal transfer body during recording. In order to prevent the transfer of the sublimable dye, an intermediate layer may be provided between the dye supply layer and the dye transfer contributing layer.

Further, a layer such as the above-mentioned intermediate layer or an anti-fusing layer with the image receiving layer may be formed on the dye transfer-contributing layer to prevent background contamination, to such an extent that the sensitivity does not decrease.

The plasticizer contained in the dye supply layer referred to in the above method (3) refers to a plasticizer that enters between the molecules of the resin, weakens van der Waals bonds that cause the rigid network structure of the resin, and consequently causes the secondary It is a substance that lowers the transition point. Compatibility is defined as a substance in which a resin and a plasticizer have an affinity for each other, have a high gelation rate, and do not separate after molding.

Also, specifically, considering the compatibility between the plasticizer and the resin, books, references, catalogs, etc., which mention the plasticizer, such as Sakura Yamada, “Plastic Compounding Agent” (published by Taiseisha, p.17 -) And "9887 Chemical Products" (published by Chemical Daily, p.745-).

For example, combinations shown in the following table are given.

In these combinations, the plasticizer and the compatible resin are used for the dye supply layer, and the incompatible resin is used for the transfer contributing layer.
As the preferred plasticizer, those described in the above table which are excellent in heat resistance and volatility are preferable, and the compounding ratio of the plasticizer to the resin is 10 to 100%, preferably 10 to 50%.

So far, an example in which the dye layer is divided into two layers has been described. However, if an appropriate difference in dye transfer amount is generated and the function separation intended by the present invention can be achieved, the dye layer may be formed into a multilayer of two or more layers. It is possible.

Although the above description has been made with reference to a recording method using a thermal head, the transfer medium of the present invention is a recording method in which recording heat energy is applied by a method other than the thermal head, for example, a thermal printing plate, a laser beam, or a support. It can also be used for a method using Joule heat generated in a medium such as a body. Of these, the so-called energetic thermal transfer method using Joule heat generated in a medium is best known, for example, USP
4,103,066, JP-A-57-14060, JP-A-57-11080, or JP-A-59-9906.

When used in this energization transfer method, relatively heat-resistant polyester, polycarbonate, triacetyl cellulose, nylon, polyimide, aromatic polyamide and other resins as a support, aluminum, copper, iron, tin, zinc,
Metal powders such as nickel, molybdenum, silver and / or conductive powders such as carbon black are dispersed to adjust the resistance to an intermediate value between the insulator and the good conductor. A support on which a conductive metal is deposited or sputtered may be used. The thickness of these supports is preferably about 2 to 15 microns in consideration of the efficiency of Joule heat conduction.

In the case of using a laser beam transfer method, a material that absorbs laser light and generates heat may be selected as a support.
For example, a conventional heat transfer film containing a light-absorbing heat exchange material such as carbon, or a film having an absorption layer formed on the front and back surfaces of a support is used.

Hereinafter, the present invention will be described more specifically based on the following examples, but the present invention is not limited thereto.

Example 1 Parts by weight Polyvinyl butyral resin BX-110 (manufactured by Sekisui Chemical Co., Ltd.) Sublimable dye KAYASET BLUE 714 (manufactured by Nippon Kayaku Co., Ltd.) Solvent Toluene 100 Methyl ethyl ketone 100 In the above formulation, for the dye supply layer The formulation was 20 parts by weight of the above-mentioned sublimable dye, and the formulation for the dye transfer contributing layer was 10 parts by weight of the above-mentioned sublimable dye. Each composition was dispersed in a ball mill for 24 hours.

Next, a sublimation type thermal transfer medium having a structure as shown in FIG. 1 was prepared as follows.

Approximately 6.0 μm aromatic polyamide film TX-I provided with a lubricating heat-resistant layer made of silicone-modified thermosetting acrylic resin
(Manufactured by Toray Co., Ltd.) was used as the substrate 1, and the ink for the dye supply layer 4 in the ink layer 2 was applied thereon with a wire bar using a wire bar to a thickness of 2.40 μm. The ink for the dye transfer contributing layer 5 is applied at 0.61 μm, dried, and thereafter, a mixed solution having the following formulation is applied thereon as an antistatic layer to a thickness of 0.5 μm using a wire bar, and dried at 100 ° C. for 1 minute. A sublimation type thermal transfer medium was formed.

Parts by weight Antistatic agent Chemistat 5500 50 (manufactured by Sanyo Kasei) (solid content: 25.2%) Water 90 Ethanol 10 Example 2 The formation up to the dye transfer contributing layer is exactly the same as in Example 1, and the antistatic is further added. As a layer, a mixed solution having the following formulation was applied using a wire bar to a thickness of about 0.5 μm, and dried at 100 ° C. for 1 minute to form a sublimation type thermal transfer medium.

Parts by weight Polyvinyl alcohol 2 Antistatic agent: Polystyrene 1 Triethanolamine sulfonic acid Water For a sublimation transfer recording medium of 100 or more, as an image receiving medium, a mixed solution of the following formulation was used on a synthetic paper 8 having a thickness of 150 μm on a wire bar. And a receiving layer 7 having a thickness of about 5 μm was used.

Parts by weight Polyester resin Byron 200 10 (manufactured by Toyobo Co., Ltd.) Silicone oil SF8417 1 (manufactured by Toray Silicone) Toluene 50 Methyl ethyl ketone 50 As shown in FIG. As printing power 442mW / dot,
FIG. 2 shows the result of performing printing many times at the same location at the maximum applied energy of 2.21 mJ / dot. However, the print density (optical density) was evaluated using a Macbeth densitometer RD-514. FIG. 2 shows the relationship between the number of printings and the saturated image density. In the thermal transfer recording media of Examples 1 and 2, even when the number of printings was increased to seven, the image density was substantially the same as that of the first printing. Did not differ. As described above, it was found that the thermal transfer recording medium of the present invention had good multi-time printing characteristics without a decrease in print density even when printing was performed many times.

The above is the result of macroscopically viewing the image as the image density.
A beautiful gradation image without image omission was obtained.

Further, in the sheets of Examples 1 and 2, almost no wrinkles were generated, and no adhesion of dust was observed.

Effect As described above, the sublimation-type thermal transfer body of the present invention in which the ink layer configuration is improved, the printing density is not substantially reduced even when the printing is performed a large number of times, and has a good multi-time printing characteristic, and further, the electrostatic The trouble caused by the gravitational force can be eliminated, and the running can be performed smoothly, and an image with less missing or unevenness in recording can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the structure of a sublimation type thermal transfer body of the present invention. FIG. 2 is a graph showing the relationship between the saturated print density of the sublimation type thermal transfer body of the present invention and the number of times of printing. 1,8 ... substrate, 2 ... ink layer 3 ... antistatic layer, 4 ... dye supply layer 5 ... transfer contributing layer, 6 ... thermal head 7 ... receiving layer

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hiroyuki Uemura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-2-2077 (JP, A) JP-A-Hei 1-258985 (JP, A) JP-A-63-281892 (JP, A) JP-A-2-16795 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B41M 5/38 -5/40

Claims (2)

(57) [Claims] 1. A sublimation type thermal transfer recording medium comprising a substrate and a dye supply layer and a dye transfer contributing layer each having a sublimable dye dispersed in an organic binder in order from the substrate side. Surface resistivity of 1 × 10 ¹⁰ Ω on the dye transfer contributing layer
A sublimation type thermal transfer recording medium comprising the following antistatic layer laminated thereon. 2. The sublimation type thermal transfer according to claim 1, wherein the dye supply layer contains at least an undissolved particulate sublimable dye, and the dye transfer contributing layer contains at least a molecularly dispersed sublimable dye. recoding media.