JP4298556B2 - Transparent gas barrier film - Google Patents

Description

  The present invention relates to a laminate having a gas barrier function. Moreover, this invention relates to the display element using said laminated body.

With the remarkable development of the information society, a technology for displaying a large amount of information, that is, a display technology, is also rapidly progressing. CRT (Cathode Ray Tube), which had a large market until now, has received a trend of space saving and low power consumption, and various FPD (Flat Panel Display), that is, liquid crystal (LCD) and plasma display panel (PDP), Furthermore, it is being replaced by organic EL displays (OELD). In particular, organic EL displays
“Because it is self-luminous, it has less viewing angle dependency.”
“Since the response speed is very fast, it is suitable for video display.”
“Since the manufacturing process is simple, the cost can be reduced.”
For these reasons, it has attracted attention as a next-generation display. One of the attractions of organic EL displays is that they can be made very thin and light because of their simple structure. On the other hand, many conventional organic EL displays have glass as a substrate, and there are limitations in terms of freedom of shape design. From this point of view, attempts have been made to replace the glass substrate used so far with a plastic substrate for flexibility. However, plastics generally have higher oxygen and water vapor permeability than glass, while organic EL elements tend to be deteriorated by oxygen and water vapor. For this reason, a plastic film excellent in gas barrier properties is required.

Conventionally, as a plastic film having gas barrier ability, a method of forming a thin film such as aluminum or an oxide thereof on a plastic film is mainly used mainly in the field of food packaging and the like, and JP-A-58-217344 (Patent Document). 1), etc., but the water vapor barrier ability achieved is about 0.5-2 g / day / m ² and is very high water vapor barrier of 10 ⁻⁵ g / day / m ² or less. This is not sufficient for substrates for organic EL display applications that are said to have high performance. In addition, there are examples using a base film coated with a plastic such as polyvinylidene chloride or polytetrafluoroethylene or a resin having a high barrier property, such as polyvinyl alcohol, but the resin has a free volume due to its structure, As a result, the change in gas barrier properties is relatively large, so that the use temperature is often limited.

As another example, a method for forming an inorganic layer as densely as possible on a plastic surface smoothed with an organic resin has been reported in Japanese Patent Laid-Open No. 9-76400 (Patent Document 2), and achieves a high gas barrier ability. It is said that this is a very effective method. However, there is a demand from the market for a resin film that can be processed into various shapes and has an excellent gas barrier property even in a wide temperature range, for development in consumer use. For this reason, a gas barrier film excellent in bending resistance, heat resistance, chemical resistance, and durability that can maintain gas barrier performance even when deformed has been demanded.
JP 58-217344 A JP-A-9-76400

  As a result of investigations by the present inventors, it has been found that the conventional gas barrier film in which the resin layer is formed for smoothing the surface causes deterioration of the inorganic thin film layer over time, and the durability is not sufficient. Further, the inventors have found out that the cause is that the inorganic thin film layer is destroyed by the water absorption of the resin layer.

  Therefore, the subject of this invention is providing the transparent gas barrier film excellent in durability, maintaining the conventional performance. Furthermore, it is providing the element for a display using said transparent gas barrier film.

As a result of investigations by the present inventors to solve the above problems, the present inventors have a laminated structure including a transparent resin base material, an organic resin layer having a specific composition and having a hydrophilic surface, and an inorganic thin film layer. The film was found to be excellent in gas barrier properties, adhesion, and heat resistance and low in water absorption, and the present invention was completed. That is, the present invention
1) a transparent resin substrate (A);
An organic resin layer (B) containing a substituent having a tertiary carbon and / or a substituent having a carbon-carbon multiple bond, and the inorganic thin film layer (C) are composed of (A) / (B) / (C) Has a laminated structure of order,
The inorganic thin film layer (C) side surface of the organic resin layer (B) is hydrophilized, and the 1 μm square average roughness (Ra) of the inorganic thin film layer (C) side surface is 0.7 nm or less and the maximum roughness ( Ry) is a transparent gas barrier film having a thickness of 7 nm or less,
2) Preferably, the organic resin layer (B) is an organic resin layer (B1) containing an acrylate resin and / or a methacrylate resin.
3) A transparent gas barrier film characterized in that the difference between the contact angle with water before and after the hydrophilic treatment on the inorganic thin film layer (C) side of the organic resin layer (B) is preferably 30 ° or more. Yes,
4) Preferably the inorganic thin film layer (C) is a transparent gas barrier film containing at least an oxide of indium,
5) An optical element for display using the above transparent gas barrier film.

  The transparent gas barrier film of the present invention has a structure including at least a transparent plastic film, an organic resin layer, and an inorganic thin film layer, and the organic resin layer has low water absorption and has a hydrophilic surface. Further, it is possible to provide a gas barrier film excellent in bending resistance, heat resistance, chemical resistance and durability.

In the gas barrier film of the present invention, the transparent resin substrate (A), the specific organic resin layer (B), and the inorganic thin film layer (C) are laminated in the order of (A) / (B) / (C 2 ). It has a structure. If it has a laminated structure in the order of (A) / (B) / (C 1 ) , the transparent resin substrate (A), the specific organic resin layer (B), and the inorganic thin film layer (C) are 2 More than one layer may be included. For example, the organic resin layer (B) and the inorganic thin film layer (C) may be alternately laminated in two or more layers as necessary, or the base material (A), the organic resin layer (B), and the inorganic thin film layer. Two or more films containing (C) may be laminated, for example, via the pressure-sensitive adhesive layer (D). Moreover, the gas barrier film of this invention may contain layers other than a base material (A), an organic resin layer (B), and an inorganic thin film layer (C) in the range which is not contrary to the objective of this invention. Examples of such a layer include functional transparent layers (E) such as an antistatic layer, a light control layer, a surface protective layer, an antifouling layer, a solvent resistance, and a light extraction efficiency improving layer. In the present invention, the adhesive layer may include an adhesive layer.

  In the present invention, “transparent” means that the visible light transmittance is 50% or more, preferably 70% or more, more preferably 80% or more. The upper limit of the visible light transmittance is 100%, but in reality, it is often 95% or less because of surface reflection and absorption by the material.

First, each layer will be described.
<Transparent resin substrate (A)>
The transparent resin substrate (A) according to the present invention is not particularly limited as long as it is a transparent film. Specifically, polyethylene, polypropylene, polystyrene, polyethylene terephthalate (PET), polysulfone, polyethersulfone, polyester, polymethyl methacrylate, polycarbonate, polyarylate, polyacetate, polyamide, poly-4-methyl 1-pentene, cellulose Examples thereof include films made of a resin having transparency such as polyvinyl chloride, polyvinyl alcohol, polyacrylate, polymethacrylate, acrylonitrile resin, phenol resin, phenylene oxide resin, and cyclic polyolefin.

  The thickness of the transparent resin substrate (A) of the present invention is not particularly limited, but is preferably 10 μm to 250 μm, preferably 50 μm to 200 μm, considering the film self-supporting property, handling property, strength, and the like.

<Organic resin layer (B)>
The organic resin layer (B) according to the present invention is constituted by so-called heteroatoms such as oxygen, nitrogen, sulfur and the like in addition to carbon and hydrogen. Since the organic resin layer (B) according to the present invention preferably has a low water absorption rate, it is preferable that the heteroatom is small. On the other hand, the base material (A) uses a material having a heteroatom such as PET. In the case, in order to improve the adhesion between the base material (A) and the organic resin layer (B), the organic resin layer (B) containing a hetero atom is preferably used.

  The organic resin layer (B) of the present invention contains a substituent having a tertiary carbon and / or a substituent having a carbon-carbon multiple bond. These substituents are hydrophobic and have a structure that easily generates radicals by plasma treatment or the like. For this reason, the water absorption rate of the organic resin layer (B) can be lowered, the surface thereof can be easily hydrophilized, and the adhesion with the inorganic thin film layer (C) described later can be improved.

  Conventionally, in a gas barrier film, the organic resin layer is generally used for improving the adhesion between the inorganic thin film layer and the substrate and smoothing the surface of the substrate film (removal of irregularities causing gas barrier defects). For this reason, when an inorganic thin film layer is formed, a resin containing many sites that easily interact with inorganic substances such as hydroxyl groups, carboxyl groups, and urethane bonds is often used so as to increase the nucleation density. However, the present inventors have found that if the organic resin layer contains a large amount of such polar groups, the resin is likely to absorb water and expand over time, and the adjacent inorganic layer may be destroyed.

  On the other hand, since the organic resin layer (B) according to the present invention has a low water absorption rate, at least the surface on the inorganic thin film layer (C) side to be described later is hydrophilized. ). For this reason, it is considered that the organic resin layer (B) is stable over time and can maintain high adhesion with the inorganic thin film layer (C) over a long period of time, that is, has high durability.

  A well-known thing can be used for the substituent which has tertiary carbon contained in the organic resin layer (B) concerning this invention, and the substituent which has a carbon-carbon double bond without a restriction | limiting. In the present invention, a substituent having a tertiary carbon refers to a substituent in which the tertiary carbon is bonded to an element other than carbon. Examples thereof include t-butyl groups and t-amyl groups such as t-butyl (meth) acrylate and t-amyl (meth) acrylate. Further, even a material generally called a primary substituent such as a 3,3-dimethyl 3-chloro 1-pentyl group has a tertiary carbon bonded to an element other than carbon in the substituent. May be.

  In particular, the substituent having a tertiary carbon or the substituent having a carbon-carbon double bond according to the present invention is a hydrocarbon group composed of only carbon and hydrogen. It is preferable for achieving both hydrophobicity and ease of hydrophilic treatment. Specific examples of these substituents include tertiary carbon groups such as t-butyl group and t-amyl group, and aromatic groups such as benzyl group, α-phenethyl group, diphenylmethyl group and triphenylmethyl group. Examples thereof include internal olefins such as a hydrocarbon group, allyl group, and methylallyl group, and groups having a carbon-carbon double bond such as a vinyl group. These groups are hydrophobic groups and have the property of easily generating radicals.

  The organic resin layer (B) of the present invention can be produced by a known polymerization method. For example, it can be obtained by polymerizing a monomer having the above substituent. Such a monomer is not particularly limited as long as it has the above-described substituent, but acrylate and methacrylate can be given as preferable examples in view of the degree of freedom in synthesizing the monomer, cost, and polymerization efficiency. . That is, the organic resin layer (B) of the present invention preferably contains an acrylic resin or a methacrylic resin. These monomers may be used independently and may be used in combination of 2 or more type. It can also be used in combination with other known monomers.

  The organic resin layer (B) according to the present invention preferably contains 3% by mass or more, particularly preferably 5% by mass or more of the above substituent. Moreover, when forming an organic resin layer (B) using the monomer which has said substituent, the said monomer has preferable 10 mass% or more of all the monomers, More preferably, it is 20 mass% or more. In addition, the above substituents are preferably formed on the side chain rather than the main chain of the polymer forming the resin. These matters can be determined from known analysis methods such as infrared spectroscopy (IR) and nuclear magnetic resonance spectrum (NMR) signals and relaxation times.

  In the production of the organic resin layer (B) according to the present invention, it is preferable to use a polyfunctional monomer for the purpose of increasing the degree of crosslinking of the resin layer and increasing the heat resistance and strength. More preferred examples include pentafunctional or higher monomers. Particularly preferable examples include dipentaerythritol hexa (meth) acrylate, dipentaerythritol penta (meth) acrylate, or a mixture thereof. These monomers are preferably contained in a weight ratio of 50% by mass to 90% by mass.

  In addition to the above, in order to improve chemical resistance, a monomer having urethane acrylate or urethane methacrylate having high cohesive strength may be used in combination. The monomer which has urethane acrylate or urethane methacrylate in this invention can use a well-known thing without a restriction | limiting. These compounds are desirably polyfunctional (meth) acrylates, particularly trifunctional or higher polyfunctional (meth) acrylates, in order to increase the degree of crosslinking upon curing. Such urethane acrylate or urethane methacrylate can be easily synthesized from, for example, an isocyanate and an acrylate or methacrylate having a hydroxyl group. The amount of the monomer having urethane acrylate or urethane methacrylate is not particularly limited. However, since the urethane structure has a high water absorption structure, the use of a large amount increases the possibility of water absorption in the urethane portion. 40% by mass or less, preferably 20% by mass or less.

  Moreover, the organic resin layer (B) used by this invention may contain the organic compound which introduce | transduced the metal alkoxide or the metal alkoxide as needed. Specifically, as the metal alkoxide, bifunctional alkoxides such as dimethyldimethoxysilane, dimethyldiethoxysilane, dialkoxyzirconium, dialkoxytitanium, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyl Trifunctional alkoxides such as triethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, trialkoxyaluminum, trialkoxyzirconium, trialkoxytitanium, tetramethoxysilane, tetraethoxysilane, Tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane, tetra-sec-butoxysilane, tetra-tert-butoxy Examples thereof include tetrafunctional metal alkoxides such as silane, tetraalkoxyzirconium, and tetraalkoxytitanium. Examples of polymerizable organic compounds into which metal alkoxide is introduced include γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-methacryloxypropylphenyldimethoxysilane, γ-methacryloxypropylphenyldiethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropylmethyldiethoxysilane, γ-acrylic Examples include loxypropyltriethoxysilane, γ-acryloxypropylphenyldimethoxysilane, and γ-acryloxypropylphenyldiethoxysilane. The amount of the organic compound into which these metal alkoxides are introduced is not particularly limited, but is preferably 20% or less, more preferably 10% by weight with respect to the total amount of the resin, from the viewpoint of preventing the above-described water absorption expansion of the resin. % Or less is desirable.

  In the present invention, a known method can be used as the polymerization method for the monomer without limitation. Among them, radical polymerization that is less affected by the polymerization atmosphere is a preferred example. The radical polymerization can be performed by various means such as heat, light, and plasma, and in this case, it is preferable to use a polymerization initiator in combination. In the present invention, the polymerization initiator is not particularly limited as long as radicals are easily generated by heat, light, plasma or the like. Specific examples include thermal polymerization initiators such as α, α'-azoisobutyronitrile, azo polymerization initiators such as α, α'-azobisisovaleronitrile, and peroxides such as benzoyl peroxide. System polymerization initiators, redox polymerization initiators and the like. As the photoinitiator, known compounds such as benzophenone and acetophenone can be used without limitation.

  The film thickness of the organic resin layer (B) in the present invention is not particularly limited because it is appropriately determined according to requirements such as production cost and surface smoothness required for various applications, but generally 0.1% It is -20 micrometers, More preferably, it is 0.1-10 micrometers.

  The organic resin layer (B) in the present invention may be formed into a film by a known method after synthesizing the above resin, but preferably applied to the substrate (A) in the state of a monomer or an oligomer. Thereafter, a method of polymerizing and curing with heat, ultraviolet rays, radiation, electron beams, plasma, or the like is a preferable example from the viewpoint of improving surface smoothness. At this time, if necessary, a solvent may be used in combination.

  As the coating method, known methods such as roll coating, gravure coating, knife coating, dip coating, spray coating, and spin coating can be used without limitation.

  The organic resin layer (B) of the present invention is preferably smooth. Specifically, it is preferable to have the same smoothness as the surface of the transparent gas barrier film of the present invention described later.

  The composition and structure of the organic resin layer (B) of the present invention can be examined by known methods such as IR and NMR. X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) can be analyzed locally and in the depth direction. For this reason, the film thickness can also be examined.

<Surface hydrophilization treatment of organic resin layer (B)>
As the surface hydrophilization treatment of the organic resin layer (B) according to the present invention, for example, a known method involving radical generation can be used without limitation. A preferable example is a method in which plasma treatment is performed in which plasma discharge is performed in the presence of a gas such as oxygen. In this method, radicals are selectively generated on the resin surface, and a highly polar hydroxyl group or carboxyl group is generated by the bond between the generated radical portion and oxygen. The treatment time and power are not particularly limited. However, when the treatment is performed with a significantly large amount of power, the surface is deteriorated and the roughness is increased. Therefore, the amount of power is preferably 1 kJ to 10 kJ, and particularly preferably 2 kJ to 5 kJ. It is.

  The contact angle of water on the surface of the organic resin layer (B) on the inorganic thin film layer (C) side is preferably 30 ° or more before and after the hydrophilic treatment. More preferably, it is 35 ° or more, and particularly preferably 40 ° or more. Moreover, the inorganic thin film layer (C) side surface of the organic resin layer (B) subjected to the hydrophilic treatment according to the present invention preferably has a contact angle with water droplets after the hydrophilic treatment described below, preferably 40 ° or less. Is preferably 30 ° or less in order to improve the adhesion to the inorganic thin film layer (C).

<Inorganic thin film layer (C)>
The inorganic thin film layer (C) according to the present invention is not particularly limited as long as it is transparent and has a gas barrier property. For example, one or more kinds of silicon, indium, tin, zinc, cerium, titanium, aluminum, and the like are used. An oxide containing metal, nitride, oxynitride, or the like can be used. As a specific example, an oxide thin film containing indium such as a silicon nitride thin film, a silicon oxynitride thin film, indium oxide, an ITO thin film made of indium, tin, and oxygen is preferable, and an oxide thin film containing indium is particularly preferable. Moreover, even if hydrogen, carbon, etc. are contained in these inorganic thin films as long as they are in a range satisfying transparency in the visible light region and desired gas barrier performance, the present invention is not inhibited at all.

  The film thickness of the inorganic thin film layer (C) in the present invention is preferably 5 to 500 nm, more preferably 10 to 200 nm, from the viewpoint of gas barrier performance and bending resistance to gas barrier performance, and is set according to various applications. It is appropriately selected according to the reflection characteristics, manufacturing cost and the like.

  The inorganic thin film layer (C) in the present invention is not necessarily a single layer, and may be composed of two or more layers having different types of compounds, refractive index, film thickness and the like. Further, by using an inorganic thin film layer having conductivity such as an ITO thin film, the inorganic thin film layer can be used as a transparent conductive layer.

  In the present invention, the inorganic thin film layer (C) typified by a silicon nitride thin film, a silicon oxynitride thin film, or an ITO thin film can be formed by a known film formation method, preferably on an organic resin layer. Specifically, a method of forming a film by sputtering or plasma CVD (chemical vapor deposition) can be exemplified. Among these, the sputtering method is preferable because the film quality can be controlled by changing the power, gas pressure, etc., and a dense film suitable for the gas barrier film can be formed. Specifically, the target is a sintered body of indium oxide and tin oxide. As an example, a method of generating plasma by a direct current (DC) or high frequency (RF) magnetron method using an inert gas such as argon or a mixed gas of argon and oxygen as a sputtering gas can be given.

  For the inorganic thin film, a film having a metal / oxygen / nitrogen composition ratio, a desired gas barrier performance and a refractive index can be obtained by selecting appropriate film forming conditions. For example, the ITO film obtains a desired gas barrier performance and a refractive index of 2 by adjusting the mass ratio of tin oxide and indium oxide as a target, and the partial pressure of a gas such as argon, oxygen, and hydrogen as a sputtering gas. It is possible to control within a range of 0.0 to 2.4. The ITO thin film layer formed by such a method not only has a high gas barrier ability but also can impart antireflection ability in addition to conductivity that can be used as a transparent electrode, for example. This is because the refractive index of the organic resin layer (B) is usually less than 2 and often 1.7 or less.

<Adhesive layer (D)>
In the present invention, the pressure-sensitive adhesive layer (D) that can be used as necessary includes a plurality of transparent gas barrier films in which an organic resin layer (B) and an inorganic thin film layer (C) are laminated on a transparent resin substrate (A). Used when necessary, for example, when laminating or laminating a transparent transparent substrate (A), an organic resin layer (B), an inorganic thin film layer (C) and a functional transparent layer (E) described later. .

  As the pressure-sensitive adhesive layer of the present invention, a known pressure-sensitive adhesive material can be used without limitation as long as it is transparent. Specifically, those described in JP-A-10-217380 and JP-A-2002-323861 can be employed.

  As the pressure-sensitive adhesive layer in the present invention, an adhesive layer can also be used. Any known adhesive can be used as long as it is transparent. Specific examples include epoxy adhesives, urethane adhesives, cyanoacrylate instantaneous adhesives, modified acrylate adhesives, and the like.

  When the pressure-sensitive adhesive layer (D) of the present invention is brought into contact with the inorganic thin film layer (C), it is preferable that the pressure-sensitive adhesive layer (D) has a low water absorption.

<Functional transparent layer (E)>
In the present invention, the functional transparent layer (E) that can be used as necessary includes an antiglare layer, a hard coat layer, an antifouling layer, an antistatic layer, a toning layer, an antireflection layer, and improved light extraction efficiency. Layers can be adopted. These layers can be used on one side or both sides of the transparent gas barrier film, or inside. Moreover, what added appropriate additives, such as an inorganic fine particle, to the organic resin layer (B) or adhesive layer (D) used by this invention can also be used as a functional transparent layer (E).

  As these functional transparent layers, those described in JP-A-10-217380 and JP-A-2002-323861 can be employed in more detail.

<Configuration of transparent gas barrier film>
In the transparent gas barrier film of the present invention, the transparent resin substrate (A), the organic resin layer (B), and the inorganic thin film layer (C) are in the order of (A) / (B) / (C). It has a laminated structure. FIG. 1 is a cross-sectional view showing an example of the configuration of the transparent gas barrier film of the present invention. The transparent gas barrier film shown in FIG. 1 can be produced, for example, by the following method. An acrylic urethane resin or the like is spin-coated as an organic resin layer 11 on a transparent plastic film 10 such as PET, and then cured with ultraviolet rays (UV). The surface of the organic resin layer 11 is hydrophilized by plasma treatment in the presence of oxygen. Finally, an inorganic thin film layer 12 such as ITO is formed by a vacuum film formation method or the like.

In addition, the transparent gas barrier film of the present invention does not need to have the above-described three-type three-layer structure within the range of the object of the present invention, and a combination in the order of (A) / (B) / (C) If it exists, it may have a multilayer structure. For example, two layers of organic resin layers and inorganic thin film layers can be alternately laminated as in (A) / (B) / (C) / (B) / (C), and the adhesive layer (D ) May be used to bond two or more transparent gas barrier films as in (A) / (B) / (C) / (D) / (A) / (B) / (C). Moreover, a functional transparent layer (E) can be formed directly or via an adhesive layer (D) as needed. In these cases, the organic resin layer (B) and the inorganic thin film layer (C) used in each layer may not be the same material and the same film thickness. For example, (C1) and (C2) having different structures are used as the inorganic thin film layer, and (A) / (B) / (C1) / (B) / (C1) / (B) / (C2) or (A ) / (B) / (C1) / (C2), or a film having a laminated structure of four or more layers. At this time, a dense film excellent in gas barrier ability such as indium oxide, silicon nitride, silicon oxynitride or the like is formed as (C1), and a film excellent in conductivity such as ITO is formed as (C2). It is possible to provide a transparent electrode having a very high gas barrier property. It is also possible to impart antireflection performance by controlling the refractive index of each of the transparent resin substrate (A), the organic resin layer (B), and the inorganic thin film layer (C). However, the increase in the number of layers may increase the manufacturing cost, and it may be difficult to control the performance of transparency, color, reflection, etc., and to maintain the yield, so the upper limit of the number of layers is preferably Is 10 layers or less, more preferably 7 layers or less.

  The transparent gas barrier film of the present invention has an average roughness (Ra) of 1 μm square on the inorganic thin film layer (C) side surface of 0.7 nm or less, preferably 0.5 nm or less, and a maximum roughness (Ry) of 7 nm or less. The thickness is preferably 5 nm or less. The average roughness and the maximum roughness are measured from a surface irregularity image using a scanning probe microscope such as AFM, and are average values of measured values at arbitrary three points. This can be achieved, for example, by mainly forming the organic resin layer (B) smoothly.

  Usually, the average roughness of the organic resin layer tends to be almost the same as or slightly larger than the average roughness of the surface of the transparent gas barrier film on the inorganic thin film layer (C) side. The tendency is stronger when the inorganic thin film layer (C) is formed by a vacuum film formation method. For this reason, in many cases, the value of the surface roughness of the organic resin layer (B) can be substituted as the value of the surface roughness of the transparent gas barrier film of the present invention.

  Since the transparent gas barrier film of the present invention has a very smooth surface, it is excellent in gas barrier properties and flex resistance. Moreover, it is excellent in chemical resistance etc. by using a crosslinked resin etc. for an organic resin layer (B). Moreover, since the water absorption rate of the organic resin layer (B) can be made relatively low, it is considered that the inorganic thin film layer is not easily broken and good gas barrier properties can be maintained over a long period of time. For this reason, it can be suitably used for various gas barrier applications. In particular, it can be suitably used for substrates of display optical elements such as organic EL elements, which are expected to rapidly spread in the future.

  An optical element for display using the transparent gas barrier film of the present invention, for example, an organic EL element, not only exhibits excellent performance as an optical element for a long period of time, but also has an advantage such as a large degree of freedom in shape. It is expected that it can be used for applications.

  In the following, embodiments of the present invention will be described. Needless to say, the present invention is not limited to such embodiments, and various modifications can be made within the technical scope obtained from the description of the scope of claims.

Example 1
A gas barrier film having the same configuration as that shown in FIG. 1 was prepared as described below.
(1) Application and curing of organic resin layer On a PET film (made by Teijin-DuPont Co., Ltd.) having a thickness of 125 μm, 100 parts by mass of an acrylic urethane UV curing resin (trade name RA1353, manufactured by Mitsui Chemicals, Inc.) On the other hand, 20 parts by mass of benzyl methacrylate and 4 parts by mass of a photopolymerization initiator (Irgacure 184 manufactured by Ciba Specialty Chemicals) were added, and a solution diluted 5 times with butyl acetate was spin-coated (2000 rpm, 10 seconds) to a thickness of 1 μm. It applied so that it might become. The coated film was dried at 60 ° C., 80 ° C., and 120 ° C. for 1 hour, and then irradiated with UV at 1000 mJ / cm to form a cured resin layer on the plastic.

(2) Oxygen Plasma Treatment of Organic Resin Layer The laminated film obtained in (1) was subjected to oxygen plasma treatment (100 W, oxygen partial pressure 10 mTorr, 30 seconds) to make the surface hydrophilic.

(3) Film formation of inorganic thin film The ITO thin film layer is formed to have a film thickness of 75 nm on the hydrophilic cured resin layer surface of the laminated film obtained in (2) by DC magnetron sputtering method (argon gas partial pressure: 2 mTorr). A transparent gas barrier film was obtained.

Here, an indium oxide / tin oxide sintered body [In ₂ O ₃ : SnO ₂ = 90: 10 (mass ratio)] was used as a target for forming a thin film layer made of an oxide of indium and tin. . The film thickness was controlled by the sputtering time after investigating the relationship between the sputtering time and the film thickness of the ITO thin film in advance.
The performance of the obtained transparent gas barrier film was evaluated by the method described later.

Example 2
A transparent gas barrier film was prepared and evaluated in the same manner as in Example 1 except that 20 parts by mass of tert-butyl acrylate was used instead of benzyl methacrylate.

Hereinafter, the comparative example of this invention is shown.
Comparative Example 1
A transparent gas barrier film was prepared and evaluated in the same manner as in Example 1 except that 100 parts by weight of dipentaerythritol pentaacrylate instead of acryl methacrylate was used instead of acrylic urethane UV curable resin (trade name RA1353 manufactured by Mitsui Chemicals, Inc.) and benzyl methacrylate. Went.

Comparative Example 2
A transparent gas barrier film was prepared and evaluated in the same manner as in Example 1 except that the ITO thin film layer was directly formed on the PET film without forming the cured resin layer.

(Evaluation)
The transparent gas barrier films produced in the above examples and comparative examples were evaluated by the following methods. The results are summarized in Table 1.

(Measurement of contact angle between cured resin layer surface and water)
In Examples 1 and 2 and Comparative Example 1, the contact angle between the surface of the cured resin layer and water was measured using a solid surface energy measuring device manufactured by Kyowa Interface Science Co., Ltd. before and after the oxygen plasma treatment.

(Measurement of surface roughness of transparent gas barrier film)
The average roughness (Ra) and the maximum roughness (Ry) at any three locations (1 μm × 1 μm) on the ITO layer side surface of the transparent gas barrier film prepared in the above examples and comparative examples were measured by an atomic force microscope (AFM: Measurement was performed using Nanoscope III (manufactured by Digital Instruments).

(Measurement of water vapor transmission rate of transparent gas barrier film)
Moisture permeability measurement was performed at a temperature of 40 ° C. and a relative humidity of 100% using Modern Control's PERMATRAN-W600. The measurement limit for this measurement is 0.02 g / day / m ² .

(Measurement of bending resistance of transparent gas barrier film)
Condition 1: The obtained transparent gas barrier film was bent 10 times along a 20 mmφ stainless steel rod at an angle of 180 °, and then the moisture permeability was measured to evaluate the bending resistance.
Condition 2: Same as Condition 1 except that the diameter of the stainless steel rod was 10 mmφ.

(Measurement of water absorption rate of resin)
A cured resin sheet having a size of 5 × 5 cm and a thickness of 3 mm was prepared using the same resin as the cured resin in Examples 1 and 2 and Comparative Example 1, and a water absorption test was performed according to JIS-K7209. The cured resin sheet was not plasma treated.

It is sectional drawing which shows an example of the transparent gas barrier film in this invention.

Explanation of symbols

10 transparent plastic film 11 organic resin layer 12 inorganic thin film layer

Claims (5)

A transparent resin substrate (A);
The organic resin layer (B) containing a t-butyl group or benzyl group and the inorganic thin film layer (C) have a laminated structure in the order of (A) / (B) / (C),
The inorganic thin film layer (C) side surface of the organic resin layer (B) is hydrophilized, and the 1 μm square average roughness (Ra) of the inorganic thin film layer (C) side surface is 0.7 nm or less and the maximum roughness ( The transparent gas barrier film whose Ry) is 7 nm or less. The transparent gas barrier film according to claim 1, wherein the organic resin layer (B) is an organic resin layer (B1) containing an acrylate resin and / or a methacrylate resin.   The transparent gas barrier according to claim 1, wherein the difference between the contact angle with water on the surface of the organic resin layer (B) on the inorganic thin film layer (C) side before and after the hydrophilic treatment is 30 ° or more. the film.     The transparent gas barrier film according to claim 1, wherein the inorganic thin film layer (C) contains at least an oxide of indium.   An optical element for display using the transparent gas barrier film according to claim 1.

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