JP5148341B2 - Plastic substrate for display element and display device - Google Patents

Description

  The present invention relates to a plastic substrate for a display element and a display capable of preventing deformation such as cracks even when surface cleaning by ultraviolet irradiation is performed on an electronic component requiring a gas barrier property against permeation of oxygen, water vapor, or the like as a flexible substrate. It relates to the device.

  2. Description of the Related Art In recent years, a display device substrate using an organic electroluminescent (hereinafter, abbreviated as an organic EL) element or a semiconductor device substrate using a semiconductor element can be made smaller and thinner. With the increase in size and portability, a flexible substrate is often used using a flexible organic resin film. For example, Patent Document 1 relates to an organic EL element substrate having high gas barrier properties and flatness that can be used for an organic EL element having a color conversion layer. A formed color conversion layer, an overcoat layer formed on the color conversion layer, a gas barrier layer comprising a vapor deposition film formed on the overcoat layer, a cardo polymer formed on the gas barrier layer A substrate for an organic EL element having a planarizing layer having a surface has been proposed. It is shown that the overcoat layer is composed of an ultraviolet curable resin.

In the flexible substrate as described above, as in the case of the conventional glass substrate, it is required to prevent foreign matter from adhering to the substrate surface. As a method of cleaning the contaminants remaining on the surface, for example, ozone is generated by the light of an ultraviolet lamp, and the organic contaminants adhered to the surface are decomposed by active oxygen generated by the decomposition of the ozone. It is being cleaned. However, in the above-mentioned flexible substrate, the UV-cured resin layer of the overcoat layer becomes brittle and decomposes when the surface cleaning by so-called UV irradiation (so-called UV cleaning) is performed, and the inorganic compound is decomposed. There is a problem that the gas barrier layer of the vapor-deposited film is cracked and the gas barrier property is lowered.
JP 2004-303562 A

  Therefore, in order to solve the above-described problems, the present invention provides a flexible substrate that is free from cracks even if it is subjected to surface cleaning by ultraviolet irradiation for electronic components that require gas barrier properties against permeation of oxygen, water vapor, and the like. An object of the present invention is to provide a plastic substrate for a display element and a display device that can prevent deformation of the above.

The invention according to claim 1 is a display in which an inorganic compound layer and an ultraviolet curable resin layer are alternately laminated at least once in this order on at least one surface of a plastic film, and an inorganic compound layer is laminated on the outermost layer. A plastic substrate for an element,
The ultraviolet curable resin layer is formed by curing a resin whose main component is an acrylic monomer having a bifunctional or higher cyclic structure.

The invention of claim 2 is for a display element in which an inorganic compound layer and an ultraviolet curable resin layer are alternately laminated at least once in this order on at least one side of a plastic film, and an inorganic compound layer is laminated on the outermost layer. A plastic substrate,
The ultraviolet curable resin layer is formed by curing a resin mainly composed of a polyester acrylate oligomer. Further, the invention of the display device according to claim 3 is that the plastic substrate for display element according to claim 1 or 2 is assembled by using the plastic substrate after surface cleaning by ultraviolet irradiation. Features.

  The present invention provides a plastic substrate for a display element in which an inorganic compound layer and an ultraviolet curable resin layer are alternately laminated at least once in this order on at least one side of a plastic film, and an inorganic compound layer is laminated on the outermost layer. The ultraviolet curable resin layer is composed of a cured resin mainly composed of an acrylic monomer having a bifunctional or higher cyclic structure, or a cured resin based on a polyester acrylate oligomer. did. As a result, even if the surface of the plastic substrate for display elements is cleaned by ultraviolet irradiation, the decomposition reaction of the ultraviolet curable resin layer by ultraviolet rays can be delayed, and deformation such as cracks on the surface of the plastic substrate can be prevented. As a result, it was possible to prevent the gas barrier property from being lowered.

  The display device of the present invention decomposes organic contaminants adhering to the surface by cleaning the surface of the plastic substrate for a display element using the cured product of the specified resin in the ultraviolet curable resin layer by ultraviolet irradiation. The display device can be assembled using the clean plastic substrate for a display element after washing. The display device was excellent in gas barrier properties, other durability, and display performance.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The plastic substrate for a display element of the present invention can be configured as shown in FIG. 1, for example. A plastic substrate 10 for a display element in which an inorganic compound layer 2 and an ultraviolet curable resin layer 3 are laminated on a plastic film 1 and an inorganic compound layer 4 is further laminated as an outermost layer. Moreover, the plastic substrate for display elements of this invention can also take a structure as shown, for example in FIG. For a display element in which an inorganic compound layer 2, an ultraviolet curable resin layer 3, an inorganic compound layer 2 ′, and an ultraviolet curable resin layer 3 ′ are laminated on a plastic film 1, and an inorganic compound layer 4 is laminated as an outermost layer. This is a plastic substrate 10.

  In the case of FIG. 2, the inorganic compound layer and the ultraviolet curable resin layer are alternately laminated twice in this order, and the inorganic compound layer 4 is provided as the outermost layer. The illustrated plastic substrate for a display element is obtained by laminating an inorganic compound layer and an ultraviolet curable resin layer alternately and once in this order on the plastic film 1, but not limited thereto, The unit of the ultraviolet curable resin layer can be three times or more. By increasing the number of units of the inorganic compound layer and the UV curable resin layer, the gas barrier property is further improved. And the ultraviolet curable resin layer are preferably provided once or twice.

Below, it demonstrates in detail for every layer which comprises the plastic substrate for display elements of this invention.
(Plastic film)
As the plastic film 1, for example, a polyolefin film such as polypropylene or polyethylene, a polyester film such as polyethylene terephthalate or polyethylene naphthalate, a polyamide film, a polycarbonate film, or other various resin films or sheets can be used. In the present invention, the film thickness of the plastic film is preferably 12 to 400 μm, more preferably 50 to 200 μm.

  The plastic film may be subjected to, for example, corona discharge treatment, ozone treatment, low temperature plasma treatment using oxygen gas or nitrogen gas, glow discharge treatment, oxidation treatment using chemicals, or other pretreatment. Can be applied arbitrarily. Further, the surface pretreatment is performed as a method for improving the adhesion between the plastic film and the inorganic oxide vapor-deposited thin film. As a method for improving the adhesion, for example, a plastic film A primer coating agent layer, an undercoat layer, a vapor deposition anchor coating agent layer, or the like can be arbitrarily formed on the surface in advance.

(Inorganic compound layer)
The inorganic compound layer in the plastic substrate for a display element of the present invention may be a layer adjacent to the plastic film, a layer sandwiched between ultraviolet curable resin layers, or an outermost layer, and any inorganic compound described below Layers can be applied. Since this inorganic compound layer can impart gas barrier properties, it can function as a gas barrier layer. The material for forming the inorganic compound layer may be any material having transparency and gas barrier properties such as oxygen and water vapor. For example, aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, zirconium oxide, oxidation Examples of the oxide include titanium, boron oxide, hafnium oxide, and barium oxide. In particular, any of silicon oxide, silicon oxynitride, and silicon oxide carbide is preferable in terms of gas barrier properties and production efficiency.

  Examples of the method for forming the inorganic compound layer include vacuum deposition, reactive deposition, ion beam assisted deposition, sputtering, ion plating, plasma CVD, and thermal CVD. . The film thickness can be appropriately set in the range of 20 to 200 nm, more preferably 50 to 150 nm. If the thickness exceeds 200 nm, the flexibility of the thin film is reduced, and the thin film may be cracked by external forces such as bending and pulling after film formation, transparency may be reduced, and the stress of the material itself may be large. It is not preferable because it is colored. On the other hand, when the thickness exceeds 200 nm, the productivity is remarkably lowered, and further, protrusions are formed from the growth of abnormal grains, and Rmax tends to increase. On the other hand, when the thickness of the inorganic compound layer is less than 20 nm, the transparency is good, but it is difficult to obtain a uniform film, the film thickness may not be sufficient, and it is difficult to sufficiently fulfill the gas barrier function. .

(UV curable resin layer)
The ultraviolet curable resin layer in the plastic substrate for a display element of the present invention is made of an ultraviolet curable resin which is a resin mainly composed of an acrylic monomer having a bifunctional or higher cyclic structure or a resin mainly composed of a polyester acrylate oligomer. It consists of a layer hardened by ultraviolet rays. Accordingly, in the present invention, “ultraviolet curable resin” means an uncured resin, and “ultraviolet curable resin” means a resin cured by ultraviolet rays.

  Specific examples of the resin mainly composed of an acrylic monomer having a bifunctional or higher functional cyclic structure in the ultraviolet curable resin layer include those having an acrylate functional group, such as dimethylol / tricyclodecane di (meth) acrylate, dimethylol Dicyclopentanedi (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, cyclohexanedimethanol di (meth) acrylate, alkoxylated cyclohexanedimethanol di (meth) acrylate, 5-ethyl-2- (2-hydroxy) -1,1-dimethylethyl) -5- (hydroxymethyl) -1,3-dioxane diacrylate, isocyanuric acid EO-modified triacrylate, and the like. In particular, in the present invention, an acrylic monomer of dimethylol tricyclodecane di (meth) acrylate is preferably used because it has a small shrinkage during polymerization and a slow decomposition reaction by ultraviolet irradiation. In this specification, “(meth) acrylate” means acrylate or methacrylate.

  The resin mainly composed of a polyester acrylate oligomer in the ultraviolet curable resin layer is a compound in which an acrylate group is bonded to a polymer having 2 to 50, preferably 2 to 20, repeating structural units of polyester. is there. As the polyester acrylate oligomer in the ultraviolet curable resin layer of the present invention, Aronix M-8030, 8060, and 9050 manufactured by Toagosei Co., Ltd. are particularly preferable because they have small shrinkage during polymerization and a slow decomposition reaction due to ultraviolet irradiation.

  Further, in the above ultraviolet curable resin, as a photopolymerization initiator, acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, tetramethylthiuram monosulfide, thioxanthones, and n- Butylamine, triethylamine, tri-n-butylphosphine, and the like can be mixed and used. This photoinitiator is 0.1-20 mass parts with respect to 100 mass parts of ultraviolet curable resin, Preferably it is about 0.5-10 mass parts.

  A composition comprising an ultraviolet curable resin which is a resin whose main component is an acrylic monomer having a bi- or higher functional cyclic structure, or a resin whose main component is a polyester acrylate oligomer, a photopolymerization initiator, a solvent and the like. Prepare and apply the composition. Examples of the coating method include commonly used coating methods such as a roll coating method, a gravure roll coating method, a kiss roll coating method, a reverse roll coating method, a Miya bar coating method, a gravure coating method, and a die coating method. After application of the resin composition, drying and curing by ultraviolet irradiation are performed.

  Specific examples of ultraviolet light sources used for ultraviolet curing include light sources such as ultra-high pressure mercury lamps, high pressure mercury lamps, low pressure mercury lamps, carbon arc lamps, black light fluorescent lamps, and metal halide lamps. As the wavelength of the ultraviolet light, a wavelength range of 190 to 380 nm can be used. The film thickness of the ultraviolet curable resin layer to be formed is preferably 1 to 10 μm, more preferably 1 to 5 μm, and most preferably 1 to 3 μm. When the film thickness is less than 1 μm, the ultraviolet curable resin layer is damaged by surface cleaning by ultraviolet irradiation, and when it exceeds 10 μm, the plastic substrate for display element is curled, making it difficult to use.

(Display device)
The display device defined by the present invention uses the plastic substrate as a part of the parts after performing surface cleaning by ultraviolet irradiation on the plastic substrate for display elements described above, and uses other parts. , Assembled. For example, the case where an organic EL (electroluminescence) element is used as the display element will be described. After forming the translucent electrode on the translucent substrate which is the plastic substrate of the present invention, the organic EL layer and the counter electrode are formed in this order to produce an organic EL element. This organic EL element emits light by applying an electric field between electrodes and passing an electric current through the EL layer. By incorporating this organic EL element into an electronic circuit, a display device that controls light emission can be obtained.

  The plastic substrate for a display element of the present invention can be applied not only to an organic EL element but also to a display device substrate on which a thin film is formed. For example, the plastic substrate for a display element of the present invention can be applied to a substrate of a self-luminous display device such as a plasma display (PDP) or a field emission display (FED) or a liquid crystal display device.

The plastic substrate for a display element of the present invention will be further described with specific examples.
Example 1
(Manufacture of plastic substrates for display elements)
A 100 μm thick PET film (Toyobo Co., Ltd., A4100: trade name) was used as a plastic film, and film formation was performed on one side using a roll-up vacuum film forming apparatus. In film formation, first, silicon was used as a target in the film formation chamber, Ar was supplied at 20 sccm and N ₂ was supplied at 15 sccm to form an inorganic compound layer of a silicon oxynitride film having a thickness of 80 nm.

On the obtained silicon oxynitride film, ARONIX M-8060 (acryloyl equivalent calculated value 136 g / equivalent) manufactured by Toagosei Co., Ltd., which is an ultraviolet curable resin mainly composed of a polyester acrylate oligomer, a photopolymerization initiator, A coating solution of a composition to which a solvent or the like has been added is applied by die coating to a film thickness of 1 μm, dried at a drying temperature of 120 ° C. for 3 minutes, and then irradiated with 150 mJ / cm ² of ultraviolet rays to form an ultraviolet curable resin layer. Formed.
Further, a silicon oxide film having a film thickness of 80 nm was formed on the ultraviolet curable resin layer as a protective layer in the same manner as the formation of the inorganic compound layer, thereby obtaining a plastic substrate for a display element.

(Example 2)
An ultraviolet curable resin mainly composed of dimethylol / tricyclodecane diacrylate represented by the following chemical formula (1), which is an acrylic monomer having a bifunctional cyclic structure, and a photopolymerization initiator; A plastic substrate for a display element was obtained under the same conditions as in Example 1 except that the coating agent was made of a composition to which a solvent or the like was added and was applied so as to have a film thickness of 1 μm.

(Example 3)
A plastic substrate for a display element was obtained under the same conditions as in Example 1 except that the coating agent for the ultraviolet curable resin layer was applied so as to have a film thickness of 5 μm.

Example 4
Except that the UV curable resin layer coating agent applied in Example 1 and Example 2 was mixed at a ratio of 1: 1 (mass ratio) so as to have a film thickness of 1.5 μm. A plastic substrate for a display element was obtained under the same conditions as in Example 1.

(Comparative Example 1)
Except for coating the UV-curable resin layer coating composition with an ultraviolet curable resin mainly composed of polyurethane oligomer and a composition obtained by adding a photopolymerization initiator, a solvent, etc., so as to have a film thickness of 1.5 μm. A plastic substrate for a display element was obtained under the same conditions as in Example 1.

(Comparative Example 2)
A plastic for a display element under the same conditions as in Example 1 except that the main component of the ultraviolet curable resin of the coating agent for the ultraviolet curable resin layer was changed to an acrylic monomer having a bifunctional linear structure and applied. A substrate was obtained.

(Evaluation conditions)
About the plastic substrate for display elements manufactured by the said Examples 1-4 and Comparative Examples 1-2 , the ultraviolet irradiation test (600mJ * 15min) was done and the surface and the curl were observed. The results are shown in Table 1 below.

(Conditions for UV irradiation)
A resin base on which a glass plate can be placed 8 mm above the iron plate is provided on the four sides of an iron plate (or SUS plate) having a thickness of 156 mm □ and a thickness of 2 mm. A test sample is placed on this glass plate. If the curl is large, 4 sides are pasted with Kapton tape or the like. In this state, the unit is set on a UV cleaning device (UV DRY PROCESSOR 120W × 7 lamp manufactured by Oak Manufacturing Co., Ltd.) and irradiated for 15 minutes. Irradiation is repeated 3 times under these conditions.

  In Table 1, “◯” in the surface appearance means that there is no bubble generation and the appearance is the same as before UV irradiation except for yellowing, and “×” indicates a spot-like thing like bubbles or bubbles by UV irradiation. The circle in the curl means that the average of the warp of the four corners when cut to 150 mm square is within 5 mm, and the × is the four corners when cut to 150 mm square This means that the average of the sum of the warpage is greater than 5 mm. However, the evaluation of the curl was measured with a cut size of 150 mm square and a concave curl toward the upper side of the horizontal plate.

  Applications of the plastic substrate of the present invention include, for example, display substrates such as liquid crystal, organic EL, inorganic EL, and touch panels, solar cell substrates, optical disk substrates, various lenses, optical filters, and the like, and are not particularly limited.

It is the schematic which shows one Embodiment which is the plastic substrate for display elements of this invention. It is the schematic which shows other embodiment which is the plastic substrate for display elements of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plastic film 2, 2 'Inorganic compound layer 3, 3' UV curable resin layer 4 Inorganic compound layer (outermost layer)
10 Plastic substrates for display elements

Claims (2)

A plastic substrate for a display element in which an inorganic compound layer and an ultraviolet curable resin layer are alternately laminated one or more times in this order on at least one surface of a plastic film, and further an inorganic compound layer is laminated on the outermost layer,
The ultraviolet curable resin layer is formed by curing a mixture of a resin mainly composed of an acrylic monomer having a cyclic structure having two or more functions and a resin mainly composed of a polyester acrylate oligomer. Plastic substrate. 2. A display device, wherein the plastic substrate for a display element according to claim 1 is assembled by using the plastic substrate after surface cleaning by ultraviolet irradiation.

Images