KR102014308B1 - Donor film comprising light diffusing layer for laser induced thermal imaging - Google Patents

Abstract

The laser beam thermal transfer donor film comprising a base layer, a photothermal conversion layer, a protective layer, and a transfer layer, and further comprising a light diffusion layer laminated on either or both of an upper surface and a lower surface of the photothermal conversion layer. The donor film is laminated with a light diffusion layer adjacent to a light heat conversion layer, which is one of the components constituting the donor film, so that the laser light applied to the donor film is uniformly irradiated onto the light heat conversion layer by the light diffusion layer. do. Therefore, the light diffusion layer is made to uniformly generate heat in the photothermal conversion layer by the laser light, thereby uniformly transferring the transfer element, for example, an organic light emitting material, and to minimize the defect by controlling the transfer width evenly. There is provided a laser light thermoelectric donor film comprising.

Description

DONOR FILM COMPRISING LIGHT DIFFUSING LAYER FOR LASER INDUCED THERMAL IMAGING

The present invention relates to a laser light thermoelectric donor film including a light diffusing layer, and more particularly, the light diffusing layer is stacked adjacent to the light-heat conversion layer, which is one of the elements constituting the donor film, by the light diffusing layer. By uniformly irradiating the laser light applied to the photothermal conversion layer to uniform heat generation in the photothermal conversion layer by the laser light thereby to transfer the transfer element, for example, an organic light emitting material uniformly, the transfer width The present invention relates to a laser light thermoelectric donor film including a light diffusing layer for controlling defects evenly.

The thermal imaging process using laser light is generally referred to as Laser Induced Thermal Imaging (LITI) or Hybrid Patterning System (HPS) and is a thermal transfer donor element. Refers to a technique for all thermal transfer elements that transfer organic or inorganic materials to other substrates and substrates.

Generally, the most common pixel formation method in an organic light emitting display device of a flat panel display is to sublimate a low molecular organic light emitting material to be deposited by aligning a fine metal mask (FMM) with a substrate in a vacuum chamber. To form a light emitting layer only in a desired area. In the case of the FMM method, due to the characteristics of the technology, there are many problems in application of a large area due to the weight of the mask frame, difficulty in stretching the mask, sag of the mask itself, expansion due to temperature, and the like. This requires a new concept of process technology. In order to replace the method of forming red, green, and blue light emitting layers individually using the existing FMM, the inkjet of the laser transfer method (LITI) and the solution process (Solution process) Ink jet), white organic light emitting diode (OLED), and color filter (Color Filter). Among them, laser technology represented by LITI and Laser Induced Pattern-wise Sublimation (LIPS) or Radiation Induced Sublimation Transfer (RIS) is applied to a donor film or donor substrate on which a light emitting layer is formed in advance. It is a technique that is separated and transferred to the acceptor substrate to form a pixel. In the case of the LITI process used to form the pixel of the organic electroluminescent device using the donor film / donor substrate including the photothermal conversion layer described above, several methods for manufacturing the donor film have been proposed.

Referring to FIG. 1, a conventional laser light thermoelectric donor film includes a base layer 1, a light-to-heat conversion layer 2, an interlayer or a buffer layer ( 3) and a transfer layer (transfer layer) consisting of a low molecular weight organic light emitting material and having a function of transferring to a substrate to form a light emitting layer.

Referring to a method of forming a light emitting layer on a substrate using the conventional laser light thermal transfer donor film, the donor film is brought into close contact with the substrate by bringing the transfer layer 4 into contact with the substrate on which the light emitting layer is to be formed. When the laser light is irradiated, as the laser light is converted into heat in the light-to-heat conversion layer 2 of the donor film to emit heat, the transfer layer 4 is transferred to the substrate to form a light emitting layer on the substrate.

Various methods have been disclosed to solve the problems occurring during the development of such donor films. For example, Korean Patent Publication No. 2007-0024816 describes a laser thermal transfer apparatus and a method of manufacturing an organic light emitting device using the same. Herein, a method for resolving unfavorable effects on the reliability and lifespan of a conventional product is described in the following description: "In a laser thermal transfer donor film comprising a photothermal conversion layer between a substrate and a transfer layer, said substrate substrate and said transfer layer. It discloses a laser thermal transfer donor film, characterized in that a permanent magnet layer is included at least in between. However, in the prior art, including the one disclosed in the above-mentioned document, there is no reference for the base substrate suitable for the laser transfer process and the optimum transmittance and optical density of the photothermal conversion layer. The disadvantage is that the process range is very narrow and has a limited transfer quality which is transferred in the high energy region.

In addition, there is also a problem that the transfer of the organic material (low molecular weight organic light emitting material) of the desired form is not made smoothly due to many pattern defects when forming a fine pattern by the laser.

In addition, in the case of a conventional donor film, in view of substantial quality control, there are the following problems.

First, foreign matters (defects) exist that cannot be controlled in the process of forming the base layer.

Second, this foreign material (defect) acts as a factor to interfere with the laser transmission in the laser thermal transfer process, the low molecular organic light emitting material in the area where the foreign material is present is a cause of defects in device manufacturing because the transfer is not performed properly.

Therefore, there is still a need for technical improvements to improve device productivity and quality by making the transfer of low molecular weight organic light emitting materials to substrates even in the presence of foreign matters that are difficult or impossible to control.

The present invention stacks a light diffusing layer adjacent to a light heat conversion layer, which is one of the elements constituting a donor film, so that the laser light applied to the donor film is uniformly irradiated to the light heat conversion layer by the light diffusing layer. Laser light thermoelectric including a light diffusing layer to uniformly generate heat in the light-to-heat conversion layer, thereby uniformly transferring the transfer element, for example, an organic light emitting material, and controlling the transfer width evenly. An object of the present invention is to provide a donor film for use.

In particular, the present invention induces the diffusion of the laser light even when there is a difficult or impossible to control in the base layer by the introduction of the light diffusion layer as described above to generate even heat in the photothermal conversion layer and thereby the low molecular organic light emitting material The object of the present invention is to enable uniform transfer, thereby improving productivity of a device, i.e., an organic light emitting diode display and the like, and minimizing pixel defects to enable production of extremely low defect rates.

The laser light thermoelectric donor film including the light diffusing layer according to the present invention includes a base layer, a photothermal conversion layer, a protective layer, and a transfer layer, and either one or both of an upper surface and a lower surface of the photothermal conversion layer. It further comprises a light diffusion layer laminated on.

The light diffusion layer preferably has a transmittance of 50 to 85% and a haze value of 60 to 90%.

The light diffusion layer is composed of a synthetic resin layer containing light diffusion particles, the resin solids and the total solid content of the synthetic resin constituting the synthetic resin layer is within the range of 20 to 50% by weight, the light The diffuse particles are transparent spherical particles having a refractive index within the range of 1.4 to 1.6, and are spherical particles of a material selected from the group consisting of polymethyl methacrylate, polystyrene, nylon, silicon, and silica, and the synthetic resin layer is polymethyl It is preferably one selected from the group consisting of methacrylates, polyesters, polyacrylates, epoxy resins, melamine resins and mixtures of two or more thereof, and from the group consisting of melamine-based resins.

In the light diffusion layer, the light diffusion particles are within the range of 40 to 70% by weight based on the total amount of solids, and the resin solid content is within the range of 25 to 55% by weight based on the total amount of solids.

According to the present invention, by providing a donor film including a light diffusion layer adjacent to the light-heat conversion layer, the laser light applied to the donor film is uniformly irradiated to the light-heat conversion layer, thereby generating heat generated in the light-heat conversion layer by the laser light. It is effective to uniformly transfer the transfer element, for example, an organic light emitting material, thereby controlling the transfer width evenly, thereby minimizing defects.

In addition, according to the present invention by providing a laser light thermal transfer donor film including a light diffusing layer by the introduction of the light diffusing layer as described above, even if there is a foreign material difficult to control or impossible in the base layer to induce the diffusion of the laser light The production of products with extremely low defect rate by improving the productivity of the device, i.e., the display of organic light emitting diodes and the like, by minimizing pixel defects by enabling even generation of heat in the conversion layer and uniform transfer of low molecular weight organic light emitting materials thereby. Provides the effect of enabling

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows typically the structure of the conventional laser beam thermoelectric donor film.
FIG. 2 is a diagram schematically illustrating a configuration of a laser light thermoelectric donor film including a light diffusing layer according to one embodiment of the present invention.
FIG. 3 is a diagram schematically illustrating a configuration of a laser light thermoelectric donor film including a light diffusing layer according to another embodiment of the present invention.
4 is a plan view of a test plate on which a pattern for measuring thermal transfer performance of a donor sheet is formed.

As shown in Figures 2 and 3, the laser beam thermoelectric donor film including the light diffusing layer according to the present invention, the base layer (1), photothermal conversion layer (2), protective layer (3) and transfer layer ( 4), but it is characterized in that it further comprises a light diffusion layer (5) laminated on any one or both of the top and bottom surfaces of the photothermal conversion layer (2).

The base layer 1, the photothermal conversion layer 2, the protective layer 3, and the transfer layer 4 are each a base layer 1, a photothermal conversion layer 2, and a protective layer 3 of a conventional donor film. And the same or similar to the transfer layer 4.

The base layer 1 serves as a mechanical support in the lowest layer of the components of the donor film, and generally, the substrate may be a glass, a transparent film, or a polymer film. One suitable type of polymer film is a polymer film having a high transmittance, i.e., at least 85% transmittance (550 nm light source), such as a polyester film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) film. . In order to be used as the base substrate of the donor film, it must be able to have high permeability as well as mechanical and thermal properties. In the case of a general donor film composed of a polymer film substrate, that is, a base layer (1), a photothermal conversion layer (2), and a protective layer (3), the direction of irradiation of the laser when the laser thermal transfer process is performed is performed. Since the photothermal conversion layer 2 region is not provided, it is confirmed under necessary conditions. In addition, the organic binder resin used in the photothermal conversion layer 2 should have a primer layer (not shown) that can control the adhesive force at the interface between the base layer 1 and the photothermal conversion layer 2. Typically, the material used to form the donor film and any adjacent layer improves adhesion between the donor film and the adjacent layer, controls the temperature transfer between the base layer 1 and the adjacent layer, and the photothermal conversion layer Can be selected to control the transmission of light for image formation to (2). As the base layer 1, polyethylene terephthalate (PET) having a thickness of 50 to 125 µm is preferable.

An example of a film that satisfies the above basic physical properties and has an optimum transmittance and excellent adhesion to the light-heat conversion layer (2) is a product No. XU series / XG series (Toray Advanced Materials Co., Ltd., Gumi, Gyeongsangbuk-do, Korea) Korea Inc.)).

The light absorbing material of the light-heat conversion layer (LTHC) coated on the base layer (1) serving as the support of the donor film absorbs an infrared laser, a visible light laser and an ultraviolet laser light, and the light-heat conversion layer (2) absorbs infrared light. It comprises a light absorbing material selected from carbon black, metal, infrared pigments and pigments that can absorb and generate thermal energy, and an organic binder resin that can be cured by ultraviolet rays or heat. The image forming laser light absorber material of the organic thin film layer, which is the transfer layer 4, is present in the thermal transfer donor film at a level sufficient to provide selected image forming laser light absorbance and to provide optical absorption at the image forming laser light wavelength. Typical laser light absorbing materials may include carbon black, metal oxides and metal sulfides. An example of a typical photothermal conversion layer 2 may include a pigment such as carbon black and a binder such as an organic polymer. Photothermal conversion layers known in the art include UV-curable resin systems and carbon black pigment dispersions as small particulate absorber materials. Carbon black is inexpensive, stable, easily processed and absorbs at near infrared (NIR) imaging laser wavelengths of 808 nm and 1064 nm.

In the case of the light absorbing material such as carbon black, which plays a key role in absorbing the laser light incident and converting it into thermal energy among the elements constituting the light-to-heat conversion layer 2, even when in the form of a liquid or a film after coating formation, It can be present in the form of nanosized controlled particles.

In particular, in the present invention, as shown in Fig. 2, a light diffusing layer 5 is formed between the light-heat conversion layer 2 and the base layer 1, or as shown in Fig. 3, the light-heat conversion The light-heat conversion layer 2 is formed by forming a light-diffusion layer 5 between the layer 2 and the protective layer 3 so as to homogeneously disperse the laser light incident on the light-heat conversion layer 2. It is characterized in that it is possible to evenly generate heat in, thereby allowing homogeneous transfer of the organic luminescent material constituting the transfer layer 4 and thereby improving patterning quality and transfer characteristics. will be. Of course, it is also possible to form the light diffusion layer 5 both between the base layer 1 and the photothermal conversion layer 2 and between the photothermal conversion layer 2 and the protective layer 3.

The light diffusing layer 5 preferably has a transmittance of 50 to 85% and a haze value of 60 to 90%. When the transmittance of the light diffusion layer 5 is less than 50%, there may be a problem in that the transmittance is low and the film defect cannot be detected. On the contrary, when the transmittance exceeds 85%, the defect of the film and the coating defect may be distinguished. There may be a problem that is missing. In addition, when the haze value of the light diffusing layer 5 is less than 60%, there may be a problem that the light diffusion effect is insignificant. On the contrary, when the haze value of the light diffusing layer 5 exceeds 90%, the transfer width becomes excessively wide during laser transfer. There may be a problem of invading adjacent pixels.

The light diffusing layer 5 is composed of a synthetic resin layer including light diffusing particles, the resin and the total solid content of the synthetic resin constituting the synthetic resin layer within the range of 20 to 50% by weight and , The light diffusing particles are transparent spherical particles having a refractive index within the range of 1.4 to 1.6, and are spherical particles of a material selected from the group consisting of polymethyl methacrylate, polystyrene, nylon, silicon and silica, the synthetic resin layer It is preferable that it is any one selected from the group which consists of this polymethyl methacrylate, polyester, polyacrylate, an epoxy resin, a melamine resin, and a mixture of 2 or more of these.

The size of the light diffusion particles is characterized in that at least one or more of 1 to 15㎛, 16 to 30㎛, 31 to 60㎛, the thickness of the diffusion layer is preferably within the range of 6 to 15㎛ according to the size of the particles. It is preferable to become.

When the total solids content is less than 20% by weight, there is a problem that the coating thickness is formed to be thin, the diffusion effect is reduced, on the contrary, when the total solids content is less than 50% by weight, the thickness deviation is large due to the excessive solids and the surface is unstable There may be issues that improve.

The light diffusion layer 5 may be used in the form of a light diffusion film in which the light diffusing particles are mixed with the binder resin in advance, before forming the donor film, and molded into a film, otherwise the light diffusion particles are mixed with the binder resin. In the manufacture of the donor film, the light diffusion layer 5 may be formed by directly coating the base layer 1 or the photothermal conversion layer 2.

The light diffusion layer 5 is that the light diffusion particles are within the range of 40 to 70% by weight based on the total amount of total solids, the resin solid content is within the range of 25 to 55% by weight based on the total amount of total solids. desirable. When the light diffusing particles are less than 40% by weight based on the total amount of the total solids, sufficient light diffusing effect is not obtained due to the lack of content of the light diffusing particles substantially performing the light diffusing function in the light diffusing layer 5. On the contrary, if it exceeds 70% by weight, the content of the resin solid content is relatively insufficient so that it becomes difficult to form a suitable light diffusion layer 5 having a uniform thickness by coating. Can be.

The transfer layer may be coated with a uniform layer, for example, by thermal deposition, sputtering or solvent coating, or spin coating, or by digital printing (e.g., For example, digital inkjet or digital electrophotographic printing), lithography printing, or printing in a pattern using deposition or sputtering through a mask, is generally formed by placing on the photothermal conversion layer (2). As previously indicated, other optional layers, for example a protective layer 3, may be interposed between the optional photothermal conversion layer 2 and the transfer layer 4. The transfer layer typically includes one or more layers for transferring to the receptor. These layers can be formed using organic, inorganic, organometallic and other materials, including, for example, electroluminescent materials or electrically active materials.

Hereinafter, although an Example demonstrates this invention more concretely, of course, it does not limit the scope of the present invention to these Examples.

Example  One

The light-diffusion layer on the film whose haze value is 60% was prepared. In addition, 1.86 weight% of photoinitiator (Brf product name Irgacure 500), dispersant (0.02 weight% LoPon 826 product name of Isoca, USA), acrylic UV curable resin (Prochem company, USA) Hs9509) 10.40% by weight, acrylic or epoxy binder resin (product name Koplex pc 974) 10.40% by weight of Koplex, U.S.A., carbon black (Toyoink, Japan) Product Op-9272A) A first coating bath solution was prepared for the formation of a photothermal conversion layer having a solid content range of 26.83% including 18.84% by weight and 34.73% by weight of solvent methyl ethyl ketone and 23.74% by weight of propylene glycol monomethyl ether as the remainder. In addition, 18.96% by weight of acrylic resin (Prochem's product name Wincure EA-127h) containing trimethylolpropane triacrylate (TMPTA) separately, 2.12% by weight of photoinitiator (Product name Irgacure 500 by BASF), additive (leveling agent; German country) A second coating bath liquid was prepared for the formation of a protective layer having a solid content range of 21.22% including 0.1 wt% of Byk333 manufactured by Byk, 39.41 wt% of solvent methyl ethyl ketone, and 39.41 wt% of toluene.

Prepare a product name XG Series PET film of Toray Advanced Materials Co., Ltd., Korea, as a base layer, and coat it with a coating thickness of 2.0 μm using the first coating bath solution thereon to form a photothermal conversion layer on the photothermal conversion layer. After laminating the light diffusing layer on the film, and then forming a protective layer having a thickness of 2.0 μm on the light-to-heat conversion layer by using the second coating bath solution, an organic light emitting material was deposited thereon to form a transfer layer. A donor film according to the invention was prepared.

Example  2

A donor film according to the present invention was prepared in the same manner as in Example 1 except that a light diffusing layer on a film having a haze value of 70% was used instead of a light diffusing layer on a film having a haze value of 60%.

Example  3

A donor film according to the present invention was prepared in the same manner as in Example 1 except that a light diffusing layer on a film having a haze value of 80% was used instead of a light diffusing layer on a film having a haze value of 60%.

Comparative example  One

A donor film according to the present invention was prepared in the same manner as in Example 1 except that the light diffusion layer on the film was not laminated on the light-to-heat conversion layer.

Experimental Example  : Laser Transfer Test

Laser light (ND: YAG) used in the LITI process using the donor films of Examples 1 to 3 and Comparative Example 1, and using a test plate having a pattern for measuring thermal transfer performance of the donor sheet as shown in FIG. 4. Thermal transfer experiments were carried out in an energy range of 60-140 w). The experimental results are shown in Table 1 below.

division Example 1 Example 2 Example 3 Comparative Example 1 Laser transfer width (㎛) 20.2 21.6 22.8 19.9 Unwarrior defect count
(Based on 1 line of transcription) 4 4 2 28  The above result is an average value of a sample of 40 mm * 40 mm.

As shown in Table 1 above, when using the light diffusing film according to the present invention compared to the donor film without the light diffusing layer of the conventional structure (Comparative Example 1), it is possible to obtain a uniform and wide transfer width, the base is not controllable As the size and frequency of transfer defects due to foreign substances present in the layer (PET layer) were reduced, it was confirmed that defects can be minimized when the device is manufactured.

In Table 1, there is a slight difference in the laser transfer width, but the laser irradiation width is the same, but the actual transfer width may vary depending on the sample, and even when the laser is irradiated on the same sample, the difference in the transfer width according to the position It may be confirmed that the better the photothermal conversion efficiency, the wider the transfer width was observed in the production site.

The present invention can be used in the industry for producing a donor film for manufacturing an optical device, such as an organic electroluminescent device, which is a kind of flat panel display, and the industry for manufacturing an optical device using the same.

1: base layer 2: photothermal conversion layer
3: protective layer 4: transfer layer
5: light diffusion layer

Claims (4)

Comprising a base layer, a photothermal conversion layer, a protective layer and a transfer layer, further comprising a light diffusion layer laminated on either or both of the top and bottom surfaces of the photothermal conversion layer,
The light diffusion layer is made of a synthetic resin layer containing light diffusion particles,
The total solid content of the resin and the total solid content of the synthetic resin constituting the synthetic resin layer is within the range of 20 to 50% by weight,
The light diffusing particles are transparent spherical particles having a refractive index within the range of 1.4 to 1.6, and are spherical particles of a material selected from the group consisting of polymethyl methacrylate, polystyrene, nylon, silicon, and silica,
Laser light thermal transfer comprising a light diffusion layer, characterized in that the synthetic resin layer is any one selected from the group consisting of polymethyl methacrylate, polyester, polyacrylate, epoxy resin, melamine resin and mixtures of two or more thereof. Donor Film. The method of claim 1,
And a light diffusing layer having a transmittance of 50 to 85% and a haze value of 60 to 90%. delete The method of claim 1,
The light diffusion layer is the light diffusion particles within the range of 40 to 70% by weight based on the total amount of total solids, the resin solid content is within the range of 25 to 55% by weight based on the total amount of total solids A laser light thermoelectric donor film comprising the light diffusion layer.

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