KR102132279B1 - Doner film for lazer induced thermal imazing - Google Patents

Abstract

In the present invention, a laser thermal transfer donor film formed by sequentially stacking a base layer, a photothermal conversion layer, and a protective layer, provides a laser thermal transfer donor film comprising light-diffusing particles in at least one of the layers. do. The donor film of the present invention is a laser heat transfer donor film according to the present invention includes light diffusing particles in constructing a photothermal conversion layer or a protective layer, so that the laser light applied to the donor film contains the light diffusing particles The conversion layer and the protective layer are uniformly irradiated to the organic light-emitting material, thereby uniformly controlling the transfer width, thereby minimizing defects. In addition, even when there is a foreign matter that is difficult or impossible to control in the PET film serving as a support, the diffusion of laser light is induced to evenly transfer heat from the photothermal conversion layer, thereby minimizing the transfer defect at the lower part where the foreign material is present. The phenomenon that heat transfer varies depending on the dispersion degree of the LTHC light absorber can also be prevented.

Description

DONER FILM FOR LAZER INDUCED THERMAL IMAZING

The present invention relates to a donor film for laser thermal transfer, and more specifically, by including light-diffusing particles in one or more layers constituting the donor film, uniform transfer is possible even in the presence of foreign matters that are difficult or impossible to control in the base layer. It is possible to use a laser thermal transfer donor film.

Among the manufacturing methods of OLED displays, which have recently been spotlighted in the field of FPD, the traditional FMM method in the R, G, and B pixel formation method is due to the characteristics of the technology, such as the weight of the mask frame, the difficulty of stretching the mask, the sag of the mask itself, and the expansion according to temperature. As a cause, there are technical limitations for large-area and high-resolution, and as a solution to this, a new concept of process technology is needed. Among many new process techniques, laser-induced thermal imaging (hereinafter referred to as LITI) is The organic film layer can be finely patterned, can be used for a large area, and has the advantage of being advantageous for high resolution, as well as ink-jet printing, which is a wet process. Accordingly, the development of a donor film, which is a core material of the thermal transfer method by laser, is also required, and the donor film is usually an optical element, in particular, an organic electroluminescent device, which forms a light to heat conversion (LTHC). It is used in a thermal image processing process using laser light, including, and is also referred to as a donor substrate or donor sheet. Patterning the organic layer on the substrate is performed while light from the light source is absorbed by the photothermal conversion layer of the donor substrate and converted into thermal energy, and the material forming the transfer layer is transferred onto the substrate by the thermal energy.

The structure of the conventional donor film uses a film as a substrate, forms a photothermal conversion layer that converts light energy into thermal energy on a film as a substrate, and forms an intermediate layer for the purpose of protecting phosphors from heat generated in the photothermal conversion layer. , Has a structure in which a phosphor is placed on the intermediate layer. The film used as the base material in this structure is usually of a polyester material. The polyester film has the advantage of being transparent and having high light transmittance and excellent heat resistance. However, the polyester film may have internal foreign matters that cannot be controlled during the film forming process, for example, iron particles, silica particles, and various carbide particles introduced or generated in the manufacturing process, and the presence of the internal foreign matters and the transmission of the laser. If it interferes, there is a possibility that the phosphor under the foreign material is not transferred or insufficient transfer occurs, resulting in pixel defects in the device.

Accordingly, the present inventors, when coating by adding optical acid particles to the photothermal conversion layer or the intermediate layer, which is a component constituting the donor film, uniformizes heat generation in the photothermal conversion layer, and accordingly, it is difficult or impossible to control the base layer Even if it exists, it was compensated for this and it was confirmed that the uniform transfer of the organic light emitting material was possible and the present invention was completed.

The object of the present invention is to uniformly transfer organic light emitting materials by forming one or more layers constituting the donor film by adding optical acid particles, thereby improving productivity of displays such as organic light emitting diodes, and defective pixels. It is to provide a donor film for laser thermal transfer that enables the production of products with extremely low defect rates by minimizing the.

In the present invention, a laser thermal transfer donor film formed by sequentially stacking a base layer, a photothermal conversion layer, and a protective layer, provides a laser thermal transfer donor film comprising light-diffusing particles in at least one of the layers. do.

The layer containing the light diffusion particles is preferably a photothermal conversion layer, a protective layer or a photothermal conversion layer and a protective layer.

It is preferable that the light-diffusing particles are transparent spherical particles having a refractive index within the range of 1.4 to 1.6.

The light diffusion particles are preferably at least one selected from the group consisting of polymethyl methacrylate particles, polystyrene particles, nylon particles, silicon particles and silica particles.

The light-heat conversion layer or the protective layer is made of a synthetic resin layer containing light-diffusing particles, but the content of the light-diffusing particles is preferably in the range of 20 to 50% by weight based on the total amount of solids.

In the laser thermal transfer donor film of the present invention, the light-diffusion particles are included in the photothermal conversion layer or the protective layer, so that the laser light applied to the donor film is formed by the light-heat conversion layer and the protective layer including the light-diffusion particles. It has the effect of uniformly irradiating the organic light emitting material, thereby minimizing defects by uniformly controlling the transfer width.

In addition, even when there is a foreign matter that is difficult or impossible to control in the PET film serving as a support, the diffusion of laser light is induced to evenly transfer heat from the photothermal conversion layer, thereby minimizing the transfer defect at the lower part where the foreign material is present. The phenomenon that heat transfer varies depending on the dispersion degree of the LTHC light absorber can also be prevented.

1 is a schematic cross-sectional view of donor films according to the present invention.
2 is a schematic diagram of a laser transfer test.

The donor film for laser thermal transfer according to the present invention is formed by sequentially stacking a base layer, a photothermal conversion layer, a protective layer, and a transfer layer.

Among the layers, the base layer serves as a support for the donor film. Typically, a general-purpose polymer film having a high transmittance such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) film is used. Preferably, it is a transparent film having a total light transmittance of 85% or more. The material used as the base film requires high transmittance in a wide wavelength range not only in the ultraviolet and visible light but also in the near-infrared region, and in addition to such optical properties, it must also have excellent mechanical/thermal properties, especially organic binder resin used in the photothermal conversion layer. Accordingly, a primer layer (not shown) may be previously formed on the base film for the purpose of adjusting the adhesive force at the interface between the base film and the photothermal conversion layer.

Optical film such as XU-series and XG-series, which meets the above basic properties and has excellent adhesion to the photothermal conversion layer, as a base film 12, commercialized as Toray Advanced Materials Co., Ltd. (Gumi, Gyeongsangbuk-do) There is a dragon/graphic film.

The photothermal conversion layer is a layer that functions to absorb light generated from one laser selected from incident radiation such as an infrared laser, a visible light laser, and an ultraviolet laser and convert it into heat. Typically, the photothermal conversion layer 14 is formed by coating a light absorbing agent that absorbs incident radiation and converts it to heat alone or with a binder. As the light absorbing agent that can be used for the photothermal conversion layer 14 of the present invention, for example, a material known in the art, such as carbon black, metal, infrared dye, and pigment, can be used. Of these, carbon black is inexpensive, stable, and easily processed, and absorbs at near-infrared ray (NIR) image forming laser wavelengths of 808 nm and 1064 nm.

The photothermal conversion layer is typically formed by coating a coating solution comprising the light absorber and an organic binder resin on a base layer, followed by curing and/or drying. As the organic binder for fixing the light absorbing agent on the base layer, for example, polymethyl methacrylate, polyester, polyacrylate, epoxy resin, melamine resin, alkyd resin, or the like may be used alone or in combination of two or more. . The coating solution comprising the light absorber and the organic binder resin is prepared by dissolving or diluting the components in an appropriate solvent so as to have a solid content of 15 to 50% by weight.

The intermediate layer 16 prevents contaminants generated by high heat generated in the process of converting light (laser) incident from the outside into heat by the light absorber into the transfer layer, and accordingly, is formed on the intermediate layer It is a layer provided for the purpose of minimizing damage, contamination and deformation of the image transferred from the transfer layer (not shown) to the receiver. The optimum thickness of the polymer film applied to the intermediate layer may be different for each material, and is usually in the range of 0.05 to 10 μm. A typical material constituting the intermediate layer is a polymer film. The material of the polymer film may be thermoplastic or thermosetting. In the case of an intermediate layer composed of a polymer film, in the case of an intermediate layer containing an organic material, a photoinitiator, surfactant, colorant, plasticizer, coating aid, and the like may be included. Organic materials suitable as interlayer materials include both thermosetting (crosslinkable) and thermoplastic materials. In all cases, the material selected for the intermediate layer must form a film and remain intact during the transfer process.

The donor film for laser transfer of the present invention is characterized in that the light-diffusing particles are included in one or more of the layers described above. The light-diffusing particles induce diffusion of laser light even in the presence of foreign matters that are difficult or impossible to control in the PET film serving as a support, thereby inducing heat evenly in the photothermal conversion layer. In addition, the phenomenon in which heat transfer varies depending on the dispersion degree of the LTHC light absorber can also be prevented. Therefore, it is possible to minimize the defective transfer.

Preferably, the light-diffusing particles are included in the light-heat conversion layer or the intermediate layer or in the light-heat conversion layer and the intermediate layer.

For example, in the first embodiment of the donor film according to the present invention, as shown in Fig. 1(a), the donor film 10 has a base layer 11, a photothermal conversion layer 12 and a protective layer 13 It is formed by sequentially stacking, and at this time, the light-diffusing particles 16 are included in the photothermal conversion layer 12 among the layers.

In the second embodiment of the donor film, as shown in Fig. 1(b), the donor film 20 is formed by sequentially stacking the base layer 21, the photothermal conversion layer 22, and the protective layer 23, At this time, the light-diffusing particles 26 are included in the protective layer 23 among the layers.

In the third embodiment of the donor film, as shown in Fig. 1(c), the donor film 30 is formed by sequentially stacking the base layer 31, the photothermal conversion layer 32, and the protective layer 33, At this time, the light diffusion particles 36 are simultaneously included in the light diffusion layer 32 and the protective layer 33 among the layers.

The light-diffusing particles used for this purpose are transparent spherical particles having a refractive index in the range of 1.4 to 1.6. If the refractive index of the light-diffusing particles is less than 1,4, the effect of diffusion may be negligible, and when it exceeds 1.6, light may be condensed and organic materials may be damaged. Preferably, one or more selected from the group consisting of polymethyl methacrylate particles, polystyrene particles, nylon particles, silicon particles and silica particles may be used.

The effect of diffusion is maximized when coating the diffused particles of the largest size as much as possible without voids, but the larger the diameter of the particles, the larger the particle size, the more the particles clump together or quickly settle, and the problem arises that the viscosity rises quickly. It is preferable that the size of the light-diffusing particles used as 15um or less.

Incorporating the light-diffusing particles into the light-heat conversion layer or the intermediate layer, it is possible to further add the light-diffusing particles to a coating solution prepared for the purpose of forming each layer. At this time, the light-diffusing particles are preferably added in a range of 20 to 50% by weight based on the total amount of solids in the coating solution.

Hereinafter, the present invention will be described in more detail through examples. This example is intended to illustrate the present invention in more detail, and the scope of the present invention is not limited to these examples.

Example One

A first coating solution having a solid content of 32% by weight was prepared, including a photoinitiator, a dispersant, an acrylic UV-curing resin, an acrylic binder resin, and light-diffusing particles for forming the photothermal conversion layer.

The light-diffusing particles contained in the photothermal conversion layer is 20% by weight compared to the total solid content, and additionally, for forming a protective layer of 23% by weight of an acrylic resin containing trimethylolpropane triacrylate (TMPTA) and a solid content comprising a photoinitiator. A second coating solution was prepared.

Toray high-tech material XD Series PET is prepared as a base layer, and on the photothermal conversion layer, a 2.0 um thick photothermal conversion layer is formed using the first coating solution, and 2.0 um is used on the photothermal conversion layer. After forming a protective layer of a thickness, Alq3 was deposited as an organic light-emitting material thereon to a thickness of 30 nm to form a transfer layer to prepare a donor film for laser thermal transfer. Below, Table 1 is a specific composition of the first coating solution, Table 2 is a second coating solution.

No Substance name input
(g) Solid content concentration (100%) Solid content Wt Wt on solid One MEK 17.7 2 PGME 12.1 3 Binder resin [Koplex pc 974, Koplex] 5.3 100 5.3 31% 4 Uv curing resin [Hs9509, Prochem] 5.3 100 5.3 31% 5 Photoinitiator [Iracure 500, Basf] 0.95 100 0.95 6% 6 Dispersant [Lopon 826, Isoca] 0.01 100 0.01 0% 7 Photothermal conversion material [Op -9272A- Toyoink] 9.6 22 2.112 12% 8 Diffusion particle [silica] 3.5 100 3.5 20% Total 54.46 17.172 100% 32%

No Substance name input
(g) Solid content concentration (100%) Solid content Wt Wt on solid One MEK 39.5 2 Toluene 39.5 4 Uv curing resin [Wincure Ea-127h,Prochem] 19 100 19 78% 5 Photoinitiator [Iracure 500, Basf] 2.12 100 2.12 9% 6 Additive [Byk333, Byk] 0.1 100 0.1 0% 8 Diffusion particle [silica] 3 100 3 12% Total 103.22 24.22 100% 23%

Example 2

A donor film according to the present invention was prepared in the same manner as in Example 1, except that 25% by weight was added instead of 20% by weight of the diffusion particles relative to the total solid content.

Example 3

A donor film according to the present invention was prepared in the same manner as in Example 1, except that 30 wt% was added instead of 20 wt% of the total solids-to-diffusion particles.

Comparative example One

A donor film according to the present invention was prepared in the same manner as in Example 1, except that the photothermal conversion layer did not contain diffusion particles.

Laser transfer test

Laser light used in the LITI process using the donor films of Examples 1 to 3 and Comparative Example 1, and using a test plate formed with a pattern for measuring the thermal transfer performance of the donor sheet as shown in FIG. 2 (ND:YAG Thermal transfer experiments were performed in an energy range of 60 to 140w (1064 nm wavelength). The experimental results are shown in Table 1 below.

division Example 1 Example 2 Example 3 Comparative Example 1 Laser transfer width (㎛) 20.3 21.5 22.9 19.7 Untransfected defect count
(Based on 1 line of transcription) 4 4 3 28 The above results are average values of samples of 40 mm * 40 mm.

In Table 1, the laser transfer width refers to the width of a pixel on which an organic material is transferred by being irradiated with a laser, and the number of untransferred defects refers to the number of defects remaining without transferring the organic material during laser irradiation. As shown in Table 1, when using a donor film coated by adding light-diffusing particles according to the present invention compared to a donor film that does not contain light-diffusing particles (Comparative Example 1), a uniform and wide transfer width can be obtained. In addition, it was confirmed that the defects can be minimized when the device is manufactured by reducing the size and frequency of transfer defects due to foreign substances present in the base layer (PET layer) that cannot be controlled.

10, 20, 30.. Donor film 11, 21, 31.. Base layer
12, 22, 32.. Photothermal conversion layer 13, 23, 33.. Protective layer
14, 24, 34.. Transfer layers 16, 26, 36.. Light-diffusing particles

Claims (5)

A laser thermal transfer donor film formed by sequentially stacking a base layer, a photothermal conversion layer and a protective layer,
The photothermal conversion layer, the protective layer or the photothermal conversion layer and the protective layer is a laser thermal transfer donor film, characterized in that the light-diffusing particles are included. delete The donor film for laser thermal transfer according to claim 1, wherein the light-diffusing particles are transparent spherical particles having a refractive index within a range of 1.4 to 1.6. The donor film for laser thermal transfer according to claim 1, wherein the light diffusion particles are at least one selected from the group consisting of polymethyl methacrylate, polystyrene, nylon, silicon and silica. The laser according to claim 1, wherein the light-heat conversion layer or the protective layer is made of a synthetic resin layer containing light-diffusing particles, wherein the content of the light-diffusing particles is within a range of 20 to 50% by weight based on the total amount of solids. Donor film for thermoelectric use.

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