JPH02227292A - Sublimable thermal transfer recording medium - Google Patents

Abstract

PURPOSE:To obtain a sublimable thermal transfer recording medium which travels smoothly and is practically free from any missing recorded data or irregularities by thinly laminating an antistatic layer consisting of resin containing an antistatic agent on a dye transfer contributing layer. CONSTITUTION:A sublimable thermal transfer recording medium consists of an ink layer 2 of a dye supply layer 4 and a dye transfer contributing layer 5, and an antistatic layer 3 formed on the base 1 of a recording medium. The antistatic layer is formed with a mixture in which an antistatic agent is kneaded in resin. Then the layer 3 is dissolved or dispersed in an organic solvent in which a binder resin is dissolved. The layer 3 is 0.1 to 3mum, and the mixture ratio of the binder and the antistatic agent is determined so that the surface resistivity after application and drying is 1X10<10>OMEGAcm or less. In addition, the dye supply layer and the dye transfer contributing layer are formed as independent layers on the base by using the same amount of the mixture for both layers. After this, these layers are placed together with another image-receiving layer respectively, and each layer is selected so that the amount of dye transferred to the image-receiving layer from the dye supply layer and the dye transfer contributing layer respectively is in the relationship of the former > the latter when the same amount of thermal energy is applied to both layers. Subsequently, the medium travels smoothly and image practically free from irregularities is obtained.

Description

[Detailed description of the invention] mutual investment and effort The present invention relates to a sublimation type thermal transfer recording medium.

In recent years, the demand for full-color printers has increased year by year, and the recording methods for these full-color printers include electrophotography.
There are inkjet methods, thermal transfer methods, etc., but among these, the thermal transfer method is often used because it is easy to maintain and is noiseless.

This thermal transfer consists of a solidified color ink sheet and an image receiving paper, and images are formed by thermally melting transferring or sublimating the ink onto the receiving paper using thermal energy controlled by electrical signals from a laser or thermal head. This is a recording method that allows

This thermal transfer recording method can be roughly divided into the above-mentioned heat-melting transfer type and sublimation transfer type. In the latter, in principle, the sublimation dye is sublimated in a monomolecular form in response to thermal energy from a thermal head, etc. This method has the advantage that halftones can be easily obtained and the gradation can be controlled at will, and is considered to be the most suitable method for full-color printers.

However, this sublimation transfer recording method uses a color ink sheet as a recording supply and selectively performs heating recording based on image signals. This method has the drawback that running costs are high because one ink sheet is used, and even if there is an unused portion, it is discarded.

Therefore, we are currently focusing on this drawback, and in an attempt to improve this drawback by using the ink sheet many times, we have developed a constant velocity mode method in which the ink sheet and image receptor are moved at a constant speed and used repeatedly, and the traveling speed of the ink sheet. An N-fold mode method has been proposed in which the overlapping portions of the first and second used portions of the coloring material layer are slightly shifted at a slower rate than that of the image receptor.

However, in the sublimation thermal transfer recording method, sublimation and evaporation reactions are basically zero-order reactions, and in constant velocity mode, even though the ink layer contains a sufficient amount of dye to withstand multiple uses, As the number of printing increases, the transfer density, especially in high image density areas, rapidly decreases, making it virtually impossible to print multiple times.

Therefore, the present inventors proposed a sublimation type heat-sensitive transfer recording medium with a laminated structure in Japanese Patent Application No. 63-62866.
Between the dye supply layer and the dye transfer contribution layer, the dye release ability is changed to "dye supply layer>dye transfer contribution layer", thereby improving the density loss caused by multiple recordings.

On the other hand, as the quality of multiple recordings improves, the drawbacks caused by static electricity have become more noticeable. For example, dust is attracted by electrostatic attraction generated by sheet running and friction, and dust adheres between the thermal transfer sheet and the receiving paper, or between the thermal head and the thermal transfer sheet, resulting in missing records (partial recording). There are problems such as damage to the elements of the thermal head, sagging of each sheet, poor running, etc., which are especially serious problems in a multiple-time system such as the one of the present invention.

■-----Surely, the present invention does not cause a rapid decrease in transfer density even with an increase in the number of printings, eliminates the above-mentioned drawbacks caused by electrostatic attraction, and runs smoothly, eliminating missing recording and unevenness. The purpose of the present invention is to provide a sublimation type thermal transfer recording medium with a small amount of use.

The present invention relates to a sublimation type thermal transfer medium comprising a dye supply layer and a dye transfer contributing layer, each of which has a sublimable dye dispersed in an organic binder, laminated on a substrate 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 is laminated thinly on the dye transfer contributing layer.

The sublimation type thermal transfer recording medium of the present invention has a structure as shown in FIG. Here, 1 indicates the base of the recording medium, and 2
3 indicates an ink layer consisting of a dye supply layer 4 and a dye transfer contributing layer 5, and 3 indicates an antistatic layer.The image receiver consists of a substrate 8 and an image receiving layer 7.

The antistatic layer is provided to facilitate the release of charges generated on the thermal transfer sheet due to charging during handling of the thermal transfer sheet, and may be formed using any electrically conductive material. However, it is usually formed using a mixture of what is called an antistatic agent kneaded into a resin.

As an antistatic agent, a cationic surfactant (for example, a quaternary surfactant) is used.
ammonium salts, polyamine derivatives, etc.), anionic surfactants (e.g., alkyl phosphates) 1
Amphoteric ionic surfactants (for example, betaine type surfactants) or nonionic surfactants (for example, fatty acid esters) can be used, and polysiloxane surfactants can also be used. In relation to the above-mentioned antistatic agents, amphoteric ionic surfactants, cationic water-soluble acrylic resins, water-soluble polystyrene resins, etc. can be used alone as a paint without a binder.

By forming a coating film with a dry coating weight of about 0.1 to 2 g/rd, it can be used as an antistatic layer, and such a water-soluble resin can be used as a colorant layer (of a thermal transfer layer) even at high temperatures.
This is preferred because it does not affect the dye (which comes into contact with the antistatic layer by stacking or rolling) and dissolves the dye.

On the other hand, there are also inorganic fine powders with excellent electronic conductivity, such as doping fine powders such as titanium oxide or zinc oxide (mixing impurities with titanium oxide or zinc oxide and baking it to form a crystal lattice of titanium oxide or zinc oxide). A fine powder of tin oxide or the like can be used.

The above-mentioned antistatic agent is used by being dissolved or dispersed in an organic solvent in which a resin to be a binder is dissolved.

The resin to be the binder is (a) a thermosetting resin, such as a thermosetting polyacrylic acid ester resin, a polyurethane resin, or (b) a thermoplastic resin 1, such as a polyvinyl chloride resin, a polyvinyl butyral resin, or a polyester resin. Resins selected from , etc. are preferable.

The prepared conductive paint is generally coated using a conventional coating method such as a blade coater or a gravure coater, or may be spray coated.

The thickness of the antistatic layer is 0.1 to 3 μm, preferably 0.1
~1μ, and the surface resistivity of the antistatic layer after coating and drying (after curing in some cases) is IX 10” Q a
The ratio of binder and antistatic agent is determined so that it is less than m. Note that the amphoteric ion type or cation type water-soluble acrylic resin is made into an alcohol solution, and added to the binder as an antistatic agent in an amount of 5 to 30% by weight in terms of solid content.
It can also be used as a paint.

The antistatic layer may contain a release agent or a filler, or a dye used in the lower layer, if necessary.

The dye supply layer and the dye transfer contribution layer are each formed as a single layer on the substrate with the same amount of adhesion according to each formulation, and each is overlapped with a separate image receiving layer, and the same thermal energy is applied to both. When applied, the amount of dye transferred to each image-receiving layer.

Dye supply layer〉Dye transfer contribution layer There is a relationship between

Thermal transfer may be performed by a thermal head, or may be performed by electrical transfer by adjusting the support layer and/or ink layer to generate Joule heat by applying electricity.

Furthermore, it is also possible to utilize a laser transfer method 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 based on Fick's law. When the average diffusion coefficient of each part in the ink layer is taken as the average diffusion coefficient of each part in the ink layer when heat is applied, the following relationship is applied: dn=-75(dc/dx)qdt.

Therefore, as a means to facilitate the diffusion and supply of the sublimable dye from the dye supply layer to the transfer contribution layer, there are the following: (1) In terms of dye concentration, the relationship is "dye supply layer > transfer contribution layer"; and/or (2) respectively. Regarding the diffusion coefficients in the layers, there is a means to establish the relationship of dye supply layer>transfer contribution layer. Furthermore, regarding the above (2), specific methods for manipulating the diffusion coefficient include, for example, Toyoko Sakai et al. Journal of the Textile Society VO1, 30, N (112 (1974)) Nobuhiko H Kuroki, "Dyeing Theory Chemistry," published by Maki Shoten, p. 503-; 1
It has been introduced in Proceedings of the 2017 Non-Impact Printing Technology Symposium 3-5. With reference to these, concrete methods for realizing the above means (1) are as follows: (1) The diffusion coefficient is influenced by the energetic suppression effect on dye diffusion due to hydrogen bonding between the dye and the organic binder. , a method of using an organic polymeric material having a large number of proton-donating groups or proton-accepting groups that easily form hydrogen bonds with sublimable dyes as a binder for the transfer contributing layer; (2) the diffusion coefficient is:
The diffusion coefficient is dependent on the glass transition or softening temperature of the organic binder in which the dye is dispersed, and the diffusion coefficient is higher when the glass transition or softening temperature is lower than the temperature rise characteristic of the layer during printing in this process. As an organic binder in the supply layer,
A method using a substance with a lower glass transition temperature or lower softening temperature than that of the transfer contributing layer.

(3) The dye supply layer contains a plasticizer that is compatible with at least one organic binder in the dye supply layer and incompatible with all the organic binders in the transfer contribution layer. Method.

(4) Methods such as appropriately combining the methods (1), (2), and (3) above may be mentioned, but the method is not limited to these methods as long as the above relationship of diffusion coefficients is satisfied. ,
Needless to say.

In designing the material formulation of the dye supply layer and transfer contribution layer in the present invention, the above! and/or ■ means are useful, and as a simple way to confirm whether the intended improvement has been achieved by these effects, it is recommended to apply the same amount of adhesion to the substrate with each formulation of the dye supply layer and the transfer contribution layer. A method of selecting each layer so that when a certain sublimation temperature is applied by forming each layer as a single layer on top of the dye layer and applying a constant sublimation temperature, the relationship is as follows: dye supply layer > transfer contribution layer There is.

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

Also, known sublimable dyes, binders, etc. can be used in the transfer contribution layer and dye supply layer of the present invention.

Sublimable dyes are dyes that sublimate or vaporize at temperatures above 60°C, and are mainly used in thermal transfer printing such as disperse dyes and oil-soluble dyes, such as C, 1, Disperse Yellow 1.3. ,8゜9.16,41,54,
60, 77.116, etc., C, 1, Dispersed thread 1, 4, 6, 11, 15, 17, 55, 59, 60,
73, 83, etc., C, 1, Disperse Blue 3, 1
4,19,26,56,60゜64.72,99,10
8, etc., C,1, solvent yellow, such as 77.116, C,1, solvent red, such as 23.25.27, C,1, solvent blue, 36.83,105, etc., and a type of these dyes. Although it is available in
It is also possible to use a mixture of several types.

Thermoplastic or thermosetting resins are used as binders for the dye transfer contributing layer and the dye supplying layer, and among them, resins with relatively high glass transition points or high softening properties include:
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.

Examples include melamine resin, natural rubber, synthetic rubber, polyvinyl alcohol, and cellulose resin.

These resins can be used alone, but several types may be mixed or a copolymer may be used.

Furthermore, when creating a difference in glass transition or softening temperature between the dye transfer contribution layer and the dye supply layer, a resin or natural 1 synthetic rubber with a glass transition temperature of 0°C or less or a softening temperature of 60°C or less is preferable. Syndiotactic 1,2-polybutadiene (commercially available JSRRB810, 820, 830 Japan Synthetic Rubber)
; olefin copolymers and terpolymers containing acids or non-acidic acids (commercially available as Dexon XEA-7, Dexon Chemical); ethylene-acid picopolymers (commercially available as 400 & 400A, 405.430, Allied Fibers &Plastics; P-3307 (EV150
), P-2807 (EV250), Mitsui DuPont Polychemicals); low molecular weight polyolefin polyols and their derivatives (Polytail H1HE Mitsubishi Chemical Industries, Ltd. as commercial products); brominated epoxy resins (YDB-340, 400)
, 500, 600 Tsukuto Kagaku); Novolac type epoxy resin (YDCN-701, 702, 703 Tsukuto Kagaku); Thermoplastic acrylic trusion (Tayanal LR107
5,1080,1081,1082,1063,107
9 Mitsubishi Rayon); thermoplastic acrylic emulsion (L
X-400, LX-450, Mitsubishi Rayon); polyethylene oxide (Alcox E-30, 45, Alcox R-150, 400, 1000 Meisei Chemical Industry);
Caprolactone polyol (Plaxel H-1,4,1
．． Daicel Chemical Industries); etc. are preferred, and polyethylene oxide and polycaprolactone polyols are particularly useful for practical purposes. is preferred.

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

Further, the dye concentration in the dye supply layer is preferably 5 to 80%, but when creating a dye concentration gradient between the dye transfer contribution layer and the dye supply layer, the dye concentration in the dye transfer contribution layer is 1%. .1 to 5 times, preferably 1.5 to 3 times.

In order to continue supplying the dye stably for a long time and maintain good printing characteristics, it is preferable that the dye supply layer contains at least undissolved particulate sublimable dye. means a dye that cannot be completely dissolved in the organic binder and precipitates in the form of particles after the ink (organic binder + sublimable dye and 10 solvents) is applied and dried during the formation of the ink layer, and the same binder and dye However, the presence of undissolved particulate dye varies depending on the solvent. The presence or absence of undissolved particulate dye can be easily identified by electron microscopy after the dye supply layer is formed. The particle size of the undissolved particulate dye varies depending on the layer thickness of the dye supply layer, but is 0.
01 μm to 20 μm, preferably 1.0 μm to 5 μm.

In addition, the state of the dye in the dye transfer contribution layer is dispersed in a monomolecular form that actually contributes to transfer, which prevents uneven transfer density and prevents the dye from forming between the dye supply layer and the dye transfer contribution layer. This is desirable because it keeps the concentration gradient stable.

Further, as the base sheet, films such as condenser paper, polyester film, polystyrene film, polysulfone film, polyimide film, polyamide film, etc. are used, and a conventional adhesive layer is provided between the base sheet and the dye supply layer as necessary. Furthermore, a conventional heat-resistant lubricant layer may be provided on the back surface of the base sheet, if necessary.

There is no way to prevent the sublimable dye from being supplied from the dye supply layer of the thermal transfer body to the dye transfer contribution layer during recording, and from the dye supply layer of the thermal transfer body during non-recording (during storage) to the dye transfer contribution layer or its surface. An intermediate layer may be provided between the dye supply layer and the dye transfer contributing layer in order to prevent migration of the sublimable dye.

Furthermore, in order to prevent background smearing, a layer such as the above-mentioned intermediate layer or a layer for preventing fusion with the image-receiving layer may be formed on the dye transfer contributing layer to an extent that does not cause a decrease in sensitivity.

The plasticizer contained in the dye supply layer in the above method (3) enters between the molecules of the resin, weakens the van der Waals bond that is the cause of the hard network structure of the resin, and as a result, the plasticizer that is contained in the dye supply layer It is a substance that lowers the transition point, and compatibility is defined as that the resin and plasticizer have affinity for each other, that the gelation rate is fast, and that the plasticizer does not separate even after molding.

While taking into consideration, books, literature, catalogs, etc. that mention plasticizers 1. For example, Yamada Jushi, "Plastic compounding agent"
(Published by Taiseisha, p. 17-) and R9887 chemical products” (Published by Kagaku Kogyo Nippo, p.

745-) etc. can be freely selected from those described in .

Examples of these include the combinations shown in the table below.

(Hereinafter, blank space) Moreover, specifically, the compatibility of the plasticizer and the resin is determined so that the plasticizer and the compatible resin are used in the dye supply layer, and the incompatible resin is used in the transfer contribution layer. Preferred plasticizers include those listed in the table above as they have excellent heat resistance and volatility, and the blending ratio of the plasticizer to the resin is 10.
-100%, preferably 10-50%.

Up until now, we have described an example in which the dye layer is divided into two layers, but
If an appropriate difference in the amount of dye transfer is created and the functional separation as intended by the present invention can be achieved, it is possible to form the dye layer into a multilayer of two or more layers.

Although the above description has been made with reference to a recording method using a thermal head, the transfer medium of the present invention can also be applied to a recording method in which recording thermal energy is applied by a method other than a thermal head, for example.
It can also be used for methods using Joule heat generated in a medium such as a thermal printing plate, laser light, or a support.

Among these, the so-called electrical thermal transfer method, which uses Joule heat generated in the medium, is the most well-known.For example, υSP4,1
03,066, JP-A-57-14060, JP-A-57-
11080, or Japanese Patent Application Laid-Open No. 59-9096.

When used in this current transfer method, aluminum, copper, iron, tin, zinc, nickel, By dispersing metal powder such as molybdenum, silver, etc. and/or conductive powder such as carbon black, the resistance value can be changed to an insulator.
The thickness of these supports should be determined by the Joule heat conduction efficiency. Considering this, it is desirable that the thickness be about 2 to 15 microns.

Also, when used in laser light transfer method.

All you need to do is choose a material that absorbs laser light and generates heat for the support.For example, you can add a light absorption heat conversion material such as carbon to a conventional thermal transfer film, or you can form an absorbing layer on the front and back sides of the support. things are used.

The present invention will be explained in more detail below based on the following examples, but the present invention is not limited thereto.

Example 1 Parts by weight Solvent Toluene 100 Methyl ethyl ketone 100 In the above formulation, the sublimable dye was 20 parts by weight in the dye supply layer formulation, 10 parts by weight in the dye transfer contribution layer formulation, and each The composition was dispersed in a ball mill for 24 hours.

Next, a sublimation type heat-sensitive transfer medium having the structure shown in FIG. 1 was prepared as follows.

Approximately 6.0 μ■ Aromatic polyamide film TX- with a slippery heat-resistant layer made of silicone-modified thermosetting acrylic resin
1 (manufactured by Toshi) as the substrate 1, and after applying the ink for the dye supply layer 4 in the ink layer 2 to a thickness of 2.40 μm using a wire bar, the ink layer 2 is further applied thereon.
0.61 μm of the above ink for the dye transfer contribution layer 5 is applied, and after drying, a mixed solution of the following formulation is applied as an antistatic layer on top of this to a thickness of 0.5 μm using a wire bar,
It was dried at 100° C. for 1 minute to form a sublimation type thermal transfer medium.

Part by weight Part by weight Polyvinyl alcohol 2 Antistatic agent:
Polystyrene 1 Sulfonic acid triethanolamine salt water 1
For sublimation transfer recording media of 00 or higher, the image receiving medium used is one in which a mixed solution of the following formulation is applied onto synthetic paper 8 with a layer thickness of 150 μm using a wire bar, and a receiving layer 7 of approximately 5 μm is provided. did.

Parts by weight water 9
0 Ethanol 10 Example 2 The formation up to the dye transfer contribution layer was exactly the same as in Example 1, and on top of this, a mixture of the following formulation was applied as an antistatic layer to a thickness of about 0.5 μm using a wire bar. Apply with 100
After drying at ℃ for 1 minute, a sublimation thermal transfer medium was formed.

Toluene 50 Methyl ethyl ketone 50 As shown in Figure 1,
Figure 2 shows the results of printing on the same spot multiple times on the above-mentioned receptor layer 7 using the thermal head 6 under the printing conditions of an applied power of 442 mW/dot and a maximum applied energy of 2.21a+J/dot. 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 7, the image density remained substantially the same as that of the first printing. No difference was observed. As described above, it was found that the thermal transfer recording medium of the present invention has good multi-printing characteristics without a decrease in print density even when printing is performed multiple times.

The above is a macroscopic result of the image density; however, from a microscopic perspective, beautiful gradation images without image omission were obtained in Examples 1 and 2.

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

- As mentioned above, the sublimation type thermal transfer material of the present invention with an improved ink layer structure does not substantially reduce the print density even after multiple printings, has good multiple printing characteristics, and furthermore It eliminates troubles caused by electrostatic attraction, provides smooth running, and provides images with fewer recording gaps and unevenness.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing the structure of the sublimation type heat-sensitive transfer material of the present invention. FIG. 2 is a graph showing the relationship between the saturated print density and the number of prints of the sublimation type thermal transfer material of the present invention. 1.8...Substrate 2...Ink layer 3...Antistatic layer 4...Dye supply layer 5...Transfer contributing layer 6...Thermal head 7...Receiving layer

Claims (1)

[Scope of Claims] 1. A sublimation type thermal transfer recording medium comprising a dye supply layer and a dye transfer contribution layer, each of which has a sublimable dye dispersed in an organic binder, laminated on a substrate in order from the substrate side. A sublimation type thermal transfer recording medium, characterized in that an antistatic layer is laminated on the dye transfer contributing layer. 2. The sublimation type thermal transfer recording medium 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.