JP2022087009A - Optical laminate and article - Google Patents

Abstract

To provide an optical laminate in which a transparent substrate and an optical layer firmly adhere to each other, and an article comprising the same.SOLUTION: An optical laminate has: a transparent substrate; an adhesion layer on at least one surface of the transparent substrate; and an optical layer on a surface of the adhesion layer opposite to the transparent substrate. The adhesion layer comprises a metal material, and the metal material has a melting point in the range from 100°C to 700°C inclusive.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical laminate and an article provided with the same.

Conventionally, optical multilayer films in which a plurality of transparent materials having a thickness of about the wavelength of light are laminated have been applied to various fields. In particular, antireflection films that reduce the reflection of light on the surface by shifting the phase of reflection, wavelength selection films that transmit or reflect only specific wavelengths, and the like have been applied to camera lenses and window glasses. In addition, the display contents of a display such as a television may be difficult to see due to the reflection of external light, and the visibility can be improved by attaching an antireflection film.

With the development of electronic technology in recent years, displays are often installed in portable devices, and high-definition displays are installed in notebook personal computers and smartphones. Furthermore, recently, with the advancement of IT in automobiles, not only conventional speedometers but also many displays displaying various information have been installed.
For such applications, weight reduction is desired from the viewpoint of portability, and it is required to form an antireflection film on a film instead of conventional glass. Further, even if the display is made of glass, in the unlikely event that it breaks, a film is attached to the surface to prevent scattering, so an antireflection film is often attached.

As a method for realizing the optical multilayer film, there are a wet method in which materials having different refractive indexes are applied in the atmosphere and a dry method in which the film-forming material is skipped in a vacuum to form a film. Although the wet method is simple, the materials that can be applied are limited, and it is difficult to form a layer having the optical properties required for the optical multilayer film, and it is difficult to stack a large number of layers. On the other hand, the method of forming a film in vacuum can stack a wide variety of materials many times. There are several dry film formation methods, but in particular, the sputtering method that uses plasma in a vacuum can form a film even on a material with a high melting point, and has various advantages such as ensuring the uniformity of the film thickness. Widely used for film formation of thin films.
In addition, since a uniform film thickness distribution can be realized for a long time by using the sputtering method, a roll-to-roll sputtering device that combines this with a film transfer device can form a large area at one time. It has industrial advantages.

However, when an optical multilayer film is formed on a film, the base film is a resin (polymer), whereas the optical thin film forming the optical multilayer film is often an oxide. Adhesion between the material and the thin film becomes an issue. In principle, the resin is an organic substance and is mainly a bond based on a covalent bond, whereas the oxide is an ionic bond and a strong bond form cannot be obtained because of a different bond form at the interface. .. Further, in general, various adsorbed molecules are attached to the surface of the film, and the surface of the film itself does not come out even when exposed to vacuum. From an industrial point of view, there are deposits such as stains on the surface of the film, and in the film production, a mold release agent or the like may be intentionally applied, which is also a factor of lowering the adhesion.

Therefore, it is necessary to improve the adhesion between the resin substrate and the oxide. Various methods have been proposed, for example, a method of roughening the surface to improve physical adhesion by using the so-called anchor effect, or a wet cleaning of the film surface in order to remove stains on the surface. Methods include introducing a polar group such as a hydroxyl group, which easily bonds with an oxide, into the surface of the substrate in advance.

In addition, plasma treatment that applies plasma to the film surface to remove stains on the film surface and form polar groups and radicals on the film surface does not significantly change the surface roughness and does not include steps such as drying. It has advantages and is widely used. In particular, the above-mentioned roll-to-roll apparatus has many advantages such as being able to continuously form a thin film after plasma-treating the film (Patent Document 1).

Further, it is also considered to introduce an adhesion layer that mediates the bonding of the resin and the oxide on the film surface. In particular, silicon has a metallic side, but the bond is a covalent bond, so it has a strong affinity with resins. Further, on the substrate side, a hard coat containing an inorganic filler is often formed in advance for the purpose of increasing the hardness of the surface and improving the slipperiness, but SiO ₂ is often used for this inorganic filler, and the filler It is possible to provide a strong adhesion between the surface and the adhesion layer of silicon (Patent Document 2). Further, an example in which silicon dioxide (SiOx: x = 1 to 2) in a state where a very small amount of oxygen is introduced during silicon film formation and a part of oxygen is deficient is used in order to form a thick adhesion layer and improve optical characteristics. There is also (Patent Document 3).

Japanese Unexamined Patent Publication No. 7-166328 Japanese Patent No. 6207679 Japanese Unexamined Patent Application Publication No. 2003-094546

However, when silicon is formed as the adhesion layer by the sputtering method, it is difficult to stably discharge the target, and once the target surface is oxidized, the discharge cannot be sustained, which causes process problems. I'm holding it. Further, when a very small amount of oxygen is introduced to form SiOx during silicon film formation, the degree of oxidation is not constant with respect to the introduced oxygen amount, and the state of the target surface depends on the previous oxygen introduction amount. It is extremely difficult to maintain the film formation under the same conditions. Therefore, even when a roll-to-roll sputtering process that can continuously form a film for a long time is used for a large area, the transparent substrate and the optical layer can be stably and firmly adhered to each other. There is a need to develop a technique that can stably form a layer.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical laminate in which a transparent base material and an optical layer are firmly adhered to each other, and an article provided with the same.

As a result of diligent studies in order to solve the above problems, the present inventor has found a condition in which a transparent base material and an optical layer can be firmly adhered to each other by using a metal material as an adhesion layer. That is, it has been found that strong adhesion can be realized by forming a film between the base material and the oxide using a metal material having a melting point of 700 ° C. or less as an adhesion layer.
Therefore, the present invention provides the following means for solving the above problems.

The optical laminate according to one aspect of the present invention is provided on a transparent substrate, an adhesion layer provided on at least one surface of the transparent substrate, and a surface of the adhesion layer on the opposite side of the transparent substrate. An optical laminate having the obtained optical layer, wherein the adhesive layer is made of a metal material, the thickness of the adhesive layer is 8 nm or less, and the metal material has a melting point of 100 ° C. or higher and 700 ° C. or lower. It is within range.

In the optical laminate according to one aspect of the present invention, the transparent base material may be a resin film.

In the optical laminate according to one aspect of the present invention, the optical layer may be configured to be an oxide layer.

In the optical laminated body according to one aspect of the present invention, the optical layer may be configured to be an alternating laminated body in which high refractive index layers and low refractive index layers are alternately laminated.

The optical laminate according to one aspect of the present invention may have a structure in which the transmittance of light having a wavelength of 550 nm is 91% or more.

The article according to one aspect of the present invention includes the above-mentioned optical laminate.

According to the present invention, it is possible to provide an optical laminate in which a transparent base material and an optical layer are firmly adhered to each other, and an article provided with the optical laminate.

It is sectional drawing which shows the optical laminated body which concerns on 1st Embodiment of this invention.

Hereinafter, the present embodiment will be described in detail with reference to the drawings as appropriate. The drawings used in the following description may be enlarged for convenience in order to make the features of the present invention easy to understand, and the dimensional ratios of each component may differ from the actual ones. be. The materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited thereto, and can be appropriately modified and carried out within the range in which the effect is exhibited.

FIG. 1 is a cross-sectional view showing an optical laminate according to the first embodiment of the present invention.
In the optical laminate 10 of the present embodiment, the adhesion layer 12 and the optical layer 13 are laminated in this order on one surface side of the transparent base material 11.

The transparent base material 11 may be formed of a transparent material capable of transmitting light in the visible light region, and for example, a resin film is preferably used. The material of the resin film is not particularly limited, but for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyaramid, polyimide, polycarbonate, polyethylene, polypropylene, triacetyl cellulose (TAC), polycycloolefin (. COC, COP) and the like can be used.

The thickness of the transparent base material 11 is not particularly limited, but in the case of a resin film, it is desirable that the thickness is 20 μm or more and 200 μm or less in consideration of ease of handling at the time of manufacturing and thinning of the member. Further, the transparent substrate 11 preferably has a light transmittance of 80% or more in the wavelength range used. The light transmittance of the transparent substrate 11 is more preferably 88% or more, and particularly preferably 90% or more.

Further, from the viewpoint of improving the scratch resistance of the optical laminate 10, for example, a coating film may be provided on at least one surface of the transparent base material 11. As the material of the coating film, a resin, an inorganic substance, or a mixture thereof can be used. When a resin film is used as the film, organic or inorganic particles may be dispersed inside the resin film for the purpose of improving the cloudiness of the optical laminate 10 and the film running property. The resin film may be formed by, for example, a solution coating method. Further, by providing the resin film on the surface of the transparent base material 11 on the adhesion layer 12 side, an auxiliary effect is provided for improving the adhesion between the transparent base material 11 and the optical layer 13.

Examples of the resin film include those provided as a hard coat layer from the viewpoint of scratch resistance. The binder resin used for the hard coat layer is preferably a transparent resin, and for example, an ionized radiation curable resin, a thermoplastic resin, a thermosetting resin, etc., which are resins that are cured by ultraviolet rays or electron beams, can be used. ..

Examples of the ionizing radiation curable resin used for the binder resin of the hard coat layer include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like.
Examples of the compound which is an ionizing radiation curable resin having two or more unsaturated bonds include trimethyl propanetri (meth) acrylate, tripropylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, and dipropylene. Glycoldi (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, Trimethylol Propanetri (meth) Acrylate, Ditrimethylol Propanetetra (meth) Acrylate, Dipentaerythritol Penta (Meta) Acrylate, Tripentaerythritol Octa (Meta) Acrylate, Tetrapentaerythritol Deca (Meta) Acrylate, Isothianulic Acid Tri (meth) acrylate, isocyanuric acid di (meth) acrylate, polyester tri (meth) acrylate, polyester di (meth) acrylate, bisphenol di (meth) acrylate, diglycerin tetra (meth) acrylate, adamantyldi (meth) acrylate, Examples thereof include polyfunctional compounds such as isoboronyldi (meth) acrylate, dicyclopentanedi (meth) acrylate, tricyclodecandi (meth) acrylate, and ditrimethylol propanetetra (meth) acrylate. Of these, pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA) and pentaerythritol tetraacrylate (PETTA) are preferably used. In addition, "(meth) acrylate" refers to methacrylate and acrylate. Further, as the ionizing radiation curable resin, a resin obtained by modifying the above-mentioned compound with PO (propylene oxide), EO (ethylene oxide), CL (caprolactone) or the like can also be used.

Examples of the thermoplastic resin used for the binder resin of the hard coat layer include styrene resin, (meth) acrylic resin, vinyl acetate resin, vinyl ether resin, halogen-containing resin, alicyclic olefin resin, and polycarbonate resin. , Polyester resin, polyamide resin, cellulose derivative, silicone resin, rubber, elastomer and the like. The thermoplastic resin is preferably amorphous and soluble in an organic solvent (particularly a common solvent capable of dissolving a plurality of polymers and curable compounds). In particular, from the viewpoint of transparency and weather resistance, styrene-based resin, (meth) acrylic-based resin, alicyclic olefin-based resin, polyester-based resin, cellulose derivative (cellulose ester, etc.) and the like are preferable.

Examples of the thermosetting resin used for the binder resin of the hard coat layer include phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, and melamine. Examples thereof include urea cocondensation resin, silicon resin, polysiloxane resin (including so-called silsesquioxane such as cage and ladder) and the like.

The hard coat layer may contain an organic resin and an inorganic material, or may be an organic-inorganic hybrid material. As an example, the one formed by the sol-gel method can be mentioned. Examples of the inorganic material include silica, alumina, zirconia, and titania. Examples of the organic material include acrylic resin.

Various fillers contained in the hard coat layer can be selected depending on the use of the optical laminate 10 from the viewpoints of antiglare property, adhesion to the optical layer described later, and anti-blocking property. Specifically, for example, known particles such as silica (Si oxide) particles, alumina (aluminum oxide) particles, and organic fine particles can be used.

The hardcourt layer may contain, for example, a binder resin and silica particles and / or alumina particles as a filler. By dispersing silica particles and / or alumina particles as a filler in the hard coat layer, fine irregularities can be formed on the surface of the hard coat layer. These silica particles and / or alumina particles may be exposed on the surface of the hard coat layer on the optical layer 13 side. In this case, the binder resin of the hard coat layer and the adhesion layer 12 at the bottom of the optical layer 13 are bonded. Therefore, the adhesion between the hard coat layer and the optical layer 13 is also improved, the hardness of the hard coat layer is increased, and the scratch resistance of the optical laminate 10 is improved.
The average particle size of the silica particles and / or the alumina particles as the filler of the hard coat layer is, for example, 800 nm or less, preferably 780 nm or less, and more preferably 100 nm or less.

From the viewpoint of improving the antiglare property of the optical laminate 10, organic fine particles can be used as the filler contained in the hard coat layer. Examples of the organic fine particles include acrylic resin. The particle size of the organic fine particles is preferably 10 μm or less, more preferably 7 μm or less, further preferably 5 μm or less, and particularly preferably 3 μm or less.
As the filler contained in the hard coat layer, various reinforcing materials can be used in order to impart toughness to the hard coat layer as long as the optical characteristics are not impaired. Examples of the reinforcing material include cellulose nanofibers.

The thickness of the hard coat layer is not particularly limited, but is preferably 0.5 μm or more, more preferably 1 μm or more, for example. The thickness of the hard coat layer is preferably 100 μm or less. When the thickness of the hard coat layer is 0.5 μm or more, sufficient hardness can be obtained, so that scratches in manufacturing are less likely to occur. Further, when the thickness of the hard coat layer is 100 μm or less, the optical laminate 10 can be made thinner and lighter. Further, when the thickness of the hard coat layer is 100 μm or less, microcracks of the hard coat layer generated when the optical laminate 10 in the process of manufacturing is bent are less likely to occur, and the productivity is improved.

The hard coat layer may be a single layer or may be a stack of a plurality of layers. Further, the hard coat layer may be further provided with known functions such as ultraviolet absorption performance, antistatic performance, refractive index adjustment function, and hardness adjustment function.
Further, the function imparted to the hard coat layer may be imparted to a single hard coat layer, or may be imparted to a plurality of layers separately.

The transparent base material 11 is not limited to the resin film. The transparent base material 11 may be, for example, glass. The glass may be a flat plate or may have a shape having an uneven surface such as a lens.

The adhesion layer 12 is a layer that adheres the transparent base material 11 and the optical layer 13.
The adhesion layer 12 is made of a metal material having a melting point of 700 ° C. or lower. The metal material may be a simple substance of metal or an alloy. Examples of the metal material include metals such as Al, Pb, Sn, In, Zn, and Bi. These metals may be alloys containing a single element or a plurality of elements. If it is Al or the like, a natural oxide film is formed, but this naturally assigned film is treated as a metal film. When the metal material is an alloy, the melting point of each of the constituent elements contained in the alloy may be 700 ° C. or higher as long as the melting point of the film formed is 700 ° C. or lower. If the film thickness of the adhesion layer 12 is too thin, the layer is not formed and the constituent atoms are localized, which may cause light absorption or impair the adhesion. Therefore, the film thickness of the adhesion layer 12 is preferably 0.5 nm or more. Further, if the film thickness of the adhesion layer 12 exceeds 8 nm, the absorption of light by the adhesion layer 12 becomes remarkable, and the light transmittance of the optical laminate 10 may be impaired. Therefore, the film thickness of the adhesion layer 12 is preferably in the range of 0.5 nm or more and 8 nm or less.

As the film forming method of the adhesion layer 12, for example, a vacuum film forming method can be used, and although it is not particularly limited, it is preferable to use a sputtering method for the purpose of obtaining adhesion.
Normally, in the sputtering method, rare gas ions accelerated by plasma collide with an adherend (sputtering target) arranged on the cathode side, and by giving an impact, the adherend jumps out into space and opposes the cathode. Atoms of the adherend collide with the arranged substrate surface to form a film. At this time, it is known that the atom moves on the surface of the substrate without stopping immediately. Atoms lose energy as they move and eventually adhere to the surface. Therefore, the larger the energy given, the more diffusion is caused on the surface and a uniform film can be formed. However, when the transparent base material 11 is a resin film, when a large number of particles having too high energy collide with each other. The thermal load becomes large, and the transparent base material 11 itself may be deformed. This phenomenon becomes more remarkable as the thickness of the transparent base material 11 becomes thinner.

Further, when a metal material having a high melting point is used as a sputtering target, sufficient energy cannot be obtained by sputtering with low power, and metal atoms aggregate on the surface of the transparent base material 11 to form metal fine particles. This can result in light absorption.

The present inventor formed a metal material film by a sputtering method using various metal materials and examined it, and found that all the metal material films having excellent adhesion have a low melting point. That is, when a metal material having a melting point of 700 ° C. or lower is used, even when the transparent base material 11 is a resin film, a strong adhesive layer 12 can be formed without causing deformation due to a thermal load. I found it.
When the adhesion layer 12 is formed by using a metal material having a melting point of 700 ° C. or lower, the electric power required to obtain the same film forming rate is smaller than that in the case of using a metal material having a high melting point. Further, a uniform film having good followability is formed even if the surface shape is complicated and the distance traveled from reaching the transparent substrate 11 to stopping on the surface of the substrate is long.
Therefore, the optical layer 13 to be formed after that is transparent because it does not come into direct contact with the transparent base material 11 but is bonded to the transparent base material 11 via the adhesion layer 12 made of a metal material having a low melting point. Even when the base material 11 is a resin film, strong adhesion can be obtained.
The melting point of the metal material used for the adhesion layer 12 may be 700 ° C. or lower, but from the viewpoint of manufacturing and processing of the sputtering target, the melting point must be 100 ° C. or higher.

The optical layer 13 is a layer for obtaining the optical effect which is the object of the optical laminate 10. The optical effect is an effect of controlling the properties of light such as reflection, transmission, and refraction, and examples thereof include an antireflection effect, a selective reflection effect, an antiglare effect, and a lens effect. In FIG. 1, the optical layer 13 is an alternating laminated body in which two layers each of a high refractive index layer 13a and a low refractive index layer 13b are alternately laminated. In FIG. 1, the number of layers of the high refractive index layer 13a and the low refractive index layer 13b is two, respectively, but the number of layers of the high refractive index layer 13a and the low refractive index layer 13b is not limited. Further, the optical layer 13 can set the material, composition, and film thickness of the layers to be laminated according to the purpose. The optical layer 13 may be a single layer.

When the optical layer 13 is used as an antireflection layer, the configuration thereof is an alternating laminate in which a high refractive index layer 13a having a refractive index of 1.9 or more and a low refractive index layer 13b having a refractive index of 1.6 or less are alternately laminated. May be. In particular, an alternating laminate in which the first high refractive index layer 13a, the first low refractive index layer 13b, the second high refractive index layer 13a, and the second low refractive index layer 13b are laminated in this order from the transparent substrate 11 side. Is often used not only to ensure sufficient optical properties but also from the viewpoint of industrial productivity. Generally, it is preferable that the high refractive index layer 13a and the low refractive index layer 13b are each transparent. In forming the transparent high refractive index layer 13a and low refractive index layer 13b, it is preferable to use these as oxides. Of course, even if a layer having optical absorption is intentionally formed in order to realize an optical function, it does not deviate from the main purpose of the present invention. Further, a substance other than an oxide such as an organic substance may intervene in the surface of the optical layer or the laminated interface excluding the interface with the base material with the intention of imparting functionality.

The refractive index of the high refractive index layer 13a is preferably 2.00 to 2.60, and more preferably 2.10 to 2.45. Examples of such an oxide having a high refractive index include niobide oxide (Nb ₂ O ₅ , refractive index 2.33), titanium oxide (TIO ₂ , refractive index 2.33 to 2.55), tungsten oxide (WO ₃ ,). Refractive index 2.2), cerium oxide (CeO ₂ , refractive index 2.2), tantalum pentoxide (Ta _{2O 5} , refractive index 2.16), zinc oxide (ZnO, refractive index 2.1), indium oxide Examples thereof include tin (ITO, refractive index 2.06).

The refractive index of the low refractive index layer 13b is preferably 1.20 to 1.60, and more preferably 1.30 to 1.50. As the oxide having such a low refractive index, an oxide containing SiO ₂ (an oxide of Si) or the like as a main component can be used. The oxide containing the oxide of Si may contain another element within 50%. For example, Na may be contained for the purpose of improving durability, and Zr, Al, or N may be contained for the purpose of improving hardness. The content of these elements is preferably 10% or less.

By alternately laminating the high refractive index layer 13a and the low refractive index layer 13b, the light incident from the surface side opposite to the transparent base material 11 interferes with each other, thereby reducing the intensity of the reflected light. , Anti-reflection function can be exhibited.

The high refractive index layer 13a and the low refractive index layer 13b constituting the optical layer 13 can be formed into a film by, for example, a sputtering method.

When the adhesion layer 12 and the optical layer 13 are formed into a film by a sputtering method, for example, the thin film forming apparatus described in Japanese Patent Application Laid-Open No. 2014-34701 can be used. For example, in this thin film forming apparatus, a supply unit for taking out a transparent base material 11 from an unwinding roll and a resin on the transparent base material 11 (when a resin film is provided on the optical layer 13 side) are provided in a vacuum chamber (chamber). It has a film forming chamber unit for forming the optical laminate 10 by forming the adhesion layer 12 and the optical layer 13 on the film-making film), and a winding unit for winding the optical laminate 10. The film forming chamber unit has a cathode portion in which a sputtering target for forming the adhesion layer 12 and the optical layer 13 is installed. In the case where the adhesion layer 12 is one layer and the optical layer 13 is an alternating laminated body in which two layers each of a high refractive index layer 13a and a low refractive index layer 13b are alternately laminated (when a total of five layers are formed), Five cathodes are used.

That is, in the above thin film forming apparatus, a film is formed by sputtering on a transparent base material 11 such as a resin film by a roll-to-roll method, and a plurality of sputtering targets can be installed. Once the roll is set, it is possible to form a plurality of different types of materials while maintaining the vacuum atmosphere. Further, in the above thin film forming apparatus, oxygen gas can be introduced into the plasma in addition to argon gas which is a sputtering gas at the time of sputtering, whereby an oxide of a sputtering target material is formed on the transparent substrate 11. be able to.

In the optical laminate 10 of the present embodiment, an antifouling layer may be provided on the surface of the optical layer 13 opposite to the adhesion layer 12 side. As the material of the antifouling layer, a fluorine-based organic compound can be used. Examples of the fluorine-based organic compound include a compound composed of a fluorine-modified organic group and a reactive silyl group (for example, alkoxysilane). One type of the fluorine-based organic compound may be used alone, or two or more types may be used in combination.

Further, in the optical laminate 10 of the present embodiment, various layers may be provided on the surface of the transparent base material 11 opposite to the adhesion layer 12 side, if necessary. For example, an adhesive layer used for adhesion to other members may be provided. Further, another optical film may be provided via this pressure-sensitive adhesive layer. Examples of other optical films include, for example, a polarizing film, a phase difference compensating film, a film that functions as a 1/2 wave plate or a 1/4 wave plate, and the like.

According to the optical laminate 10 of the present embodiment having the above configuration, the adhesion layer 12 interposed between the transparent base material 11 and the optical layer 13 has a melting point within the range of 100 ° C. or higher and 700 ° C. or lower. Since it is formed of the metal material in the above, the transparent base material 11 and the optical layer 13 can be firmly adhered to each other. That is, a metal material having a melting point in the range of 100 ° C. or higher and 700 ° C. or lower can be formed into a film with relatively low power by a sputtering method, so that even when the transparent base material 11 is a resin film, the metal is uniformly metal. It becomes possible to form a material film (adhesion layer 12). Since the adhesion layer 12 is uniformly formed on the surface of the transparent base material 11, it is difficult for the optical layer 13 to come into direct contact with the surface of the transparent base material 11, and the optical layer 13 is formed on the surface of the adhesion layer 12. Since the film is uniformly formed, the adhesion between the transparent substrate 11 and the optical layer 13 is improved.
Further, when the transparent base material 11 is provided with the resin film, the same action as described above when the transparent base material 11 is a resin film can be said for the resin film.

In the optical laminate 10 of the present embodiment, when the thickness of the adhesion layer 12 is 0.5 nm or more, the transparent base material 11 and the optical layer 13 can be more reliably adhered to each other. Further, when the thickness of the adhesion layer 12 is 8 nm or less, the absorption of light by the adhesion layer 12 can be suppressed to a level that does not cause a practical problem.

According to the optical laminate 10 of the present embodiment, even when the transparent base material 11 is a resin film and the optical layer 13 is an oxide layer, it can be firmly adhered.

In the optical laminated body 10 of the present embodiment, when the optical layer 13 is an alternating laminated body in which the high refractive index layer 13a and the low refractive index layer 13b are alternately laminated, it can be used as an antireflection film. In particular, when the transmittance of light having a wavelength of 550 nm is 91% or more, it can be advantageously used as an antireflection film.

The article of the present embodiment is provided with the above-mentioned optical laminate 10 on the display surface of the image display unit, such as a liquid crystal display panel or an organic EL display panel. As a result, for example, it is possible to impart high wear resistance to the touch panel display unit of a smartphone or an operating device, and it is possible to realize an image display device having excellent durability.

Further, the article is not limited to the image display device, for example, a window glass or goggles on which the optical laminate of the present embodiment is provided on the surface, a light receiving surface of a solar cell, a screen of a smartphone, or a display of a personal computer. If the optical laminate 10 is applicable, such as an information input terminal, a tablet terminal, an electric display board, a glass table surface, a game machine, an operation support device for an aircraft or a train, a navigation system, an instrument panel, or an optical sensor surface. , Anything is fine.

Although the embodiment of the present invention has been described above, this embodiment is presented as an example and is not intended to limit the scope of the invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope of the invention described in the claims and the equivalent scope thereof, as are included in the scope and gist of the invention.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Example 1]
As the transparent base material 11, a resin film having an acrylic resin film (hard coat layer) containing silicon oxide fine particles formed in 4 μm on a TAC having a thickness of 80 μm was prepared. The adhesion layer 12 and the optical layer 13 were sequentially formed on the acrylic resin film of this resin film by a sputtering method using a thin film forming apparatus.

The acrylic resin film was formed by a method in which a coating liquid having the composition shown in Table 1 below was applied onto the transparent substrate 11 using a bar coater, irradiated with ultraviolet rays, photopolymerized, and cured.

As the thin film forming apparatus, the apparatus described in JP-A-2014-34701 was used. This thin film forming apparatus can sequentially stack thin films of a plurality of materials at the same time. In this embodiment, the sputtering targets of aluminum, niobium oxide, silicon, niobium oxide, and silicon are arranged in this order from the side closer to the unwinding side of the resin film. Each sputtering target is connected to an independent power source and can be charged with arbitrary power to discharge. In addition, each sputtering target is housed in an independent container, and the partition wall separating the sputtering targets has only a slight gap near the can roll, and it is possible to realize a substantially different gas atmosphere. be.

The entire inside of the vacuum chamber of this thin film forming apparatus was evacuated to 1 × 10 ^-3 Pa or less. Next, argon gas is introduced into the first cathode portion where the aluminum target is installed while adjusting the flow rate to 150 sccm with a mass flow controller, and power is applied to the aluminum target to discharge the film. Was done. The traveling speed of the resin film at this time is 3 m / min. Met. The electric power applied to the aluminum target has a traveling speed of 3 m / min by measuring the relationship between the electric power and the film thickness of the formed aluminum film in advance. It was adjusted so that an aluminum film having a film thickness of 0.5 nm could be formed on the resin film of.

An aluminum film (adhesive layer) was formed on the first cathode portion, and then a niobium oxide film (high refractive index layer 13a) was formed on the second cathode portion. Argon gas was introduced into the second cathode portion while being adjusted by a mass flow controller so as to have a flow rate of 150 sccm, and electric power was applied to the niobium oxide target to discharge it, and a film was formed by sputtering. At this time, a small amount of oxygen was introduced while adjusting with a mass flow controller separately from the argon gas, and the amount of oxygen was adjusted so as not to cause light absorption due to lack of oxygen to obtain a good niobium oxide film. The electric power applied to the niobium oxide target has a traveling speed of 3 m / min by measuring the relationship between the electric power and the film thickness of the formed niobium oxide film in advance. It was adjusted so that a niobium oxide layer having a film thickness of 10 nm could be formed on the resin film of.

After forming a niobium oxide film (high refractive index layer) at the second cathode portion, a silicon oxide film (low refractive index layer) was formed at the third cathode portion. Argon gas was introduced into the third cathode portion while adjusting with a mass flow controller so as to have a flow rate of 150 sccm, and electric power was applied to the silicon target to discharge the silicon target to form a film by sputtering. At this time, oxygen was introduced while adjusting with a mass flow controller separately from the argon gas to obtain a good silicon oxide film. The electric power applied to the silicon target has a traveling speed of 3 m / min by measuring the relationship between the electric power and the film thickness of the formed silicon oxide film in advance. It was adjusted so that silicon oxide having a film thickness of 40 nm could be formed on the resin film of.

Similarly, a niobium oxide film was formed on the fourth cathode portion, and then a silicon oxide film was formed on the fifth cathode portion. At that time, the electric power was adjusted so that the film thickness of the niobium oxide film was 100 nm at the fourth cathode portion and the thickness of silicon oxide at the fifth cathode portion was 90 nm.

As described above, an optical layer, which is an alternating laminated body in which one adhesive layer 12 and four layers of high refractive index layers and low refractive index layers are alternately laminated, is formed on the resin film. , An optical laminate (antireflection film) having the configuration shown in FIG. 1 was produced. After the optical laminate was continuously wound, the atmosphere was introduced into the entire vacuum chamber of the thin film forming apparatus, and the wound optical laminate was taken out.

In this embodiment, one layer is formed by using one cathode, but it is not always necessary to use one cathode. One layer may be formed by using a plurality of cathodes in consideration of a thermal load and a power load.

[Example 2]
An optical laminate was produced under the same conditions as in Example 1 except that the film thickness of the aluminum film (adhesive layer) was adjusted to 1 nm in the first cathode portion.

[Example 3]
An optical laminate was produced under the same conditions as in Example 1 except that the film thickness of the aluminum film (adhesive layer) was adjusted to 2 nm in the first cathode portion.

[Example 4]
An optical laminate was produced under the same conditions as in Example 1 except that the film thickness of the aluminum film (adhesive layer) was adjusted to 4 nm in the first cathode portion.

[Example 5]
An optical laminate was produced under the same conditions as in Example 1 except that the film thickness of the aluminum film (adhesive layer) was adjusted to 6 nm in the first cathode portion.

[Example 6]
An optical laminate was produced under the same conditions as in Example 1 except that the film thickness of the aluminum film (adhesive layer) was adjusted to 8 nm in the first cathode portion.

[Example 7]
In the first cathode portion, a zinc target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the zinc film (adhesive layer) was adjusted to 2 nm. Made.

[Example 8]
In the first cathode portion, a tin target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the tin film (adhesive layer) was adjusted to 2 nm. Made.

[Example 9]
In the first cathode portion, an indium target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the indium film (adhesive layer) was adjusted to 2 nm. Made.

[Comparative Example 1]
In the first cathode portion, an optical laminate was produced under the same conditions as in Example 1 except that the cathode portion was not discharged and the aluminum film was not formed.

[Comparative Example 2]
In the first cathode portion, a titanium target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the titanium film (adhesive layer) was adjusted to 1 nm. Made.

[Comparative Example 3]
In the first cathode portion, a titanium target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the titanium film (adhesive layer) was adjusted to 2 nm. Made.

[Comparative Example 4]
In the first cathode portion, a titanium target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the titanium film (adhesive layer) was adjusted to 3 nm. Made.

[Comparative Example 5]
In the first cathode portion, a titanium target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the titanium film (adhesive layer) was adjusted to 4 nm. Made.

[Comparative Example 6]
In the first cathode portion, a silver target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the silver film (adhesive layer) was adjusted to 2 nm. Made.

[Comparative Example 7]
In the first cathode portion, a silver target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the silver film (adhesive layer) was adjusted to 4 nm. Made.

[Comparative Example 8]
In the first cathode portion, a germanium target was used instead of the aluminum target, and the optical laminate was prepared under the same conditions as in Example 1 except that the film thickness of the germanium film (adhesive layer) was adjusted to 2 nm. Made.

[Comparative Example 9]
In the first cathode portion, a germanium target was used instead of the aluminum target, and the optical laminate was prepared under the same conditions as in Example 1 except that the film thickness of the germanium film (adhesive layer) was adjusted to 4 nm. Made.

[Comparative Example 10]
In the first cathode portion, a tungsten target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the tungsten film (adhesive layer) was adjusted to 2 nm. Made.

[Comparative Example 11]
In the first cathode portion, a tungsten target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the film thickness of the tungsten film (adhesive layer) was adjusted to 4 nm. Made.

[Comparative Example 12]
In the first cathode portion, an indium target was used instead of the aluminum target, and the optical laminate was formed under the same conditions as in Example 1 except that the thickness of the indium film (adhesive layer) was adjusted to 10 nm. Made.

[Evaluation results]
The following measurements and evaluations were carried out on samples prepared by cutting out the optical laminates obtained in Examples and Comparative Examples to an arbitrary size. The results are shown in Table 2 below, together with the metal material constituting the adhesion layer, the bulk melting point of the metal, and the film thickness of the adhesion layer.

(Total light transmittance)
The total light transmittance was measured using "NDH5000" (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with "JIS K-7105". In the present invention, it is preferable that the light absorption by the adhesion layer is small. Therefore, in the case of the optical laminate (antireflection film) produced in Examples and Comparative Examples, it is desirable that the total light transmittance is high. Since the TAC film without the antireflection film has a transmittance of about 90%, the total light transmittance is increased by applying the antireflection film in order to exert the function as the antireflection film. Is desirable to be 91% or more.

(Adhesion)
Adhesion was evaluated by the cross-hatch method in accordance with "JIS K5400". That is, 11 cuts are made on the surface of the sample on the optical laminate side at 1 mm intervals with a cutter, and 11 cuts are made so as to be orthogonal to the cuts to form 100 squares. The sample on which the squares are formed is allowed to stand for 2 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 60% RH, and then the adhesive tape is adhered to the squares and peeled off at once in a state where no bubbles enter. This is repeated 3 times, and the number of peeled squares is measured with an optical microscope or the like. It should be noted that the peeling is defined as the peeling of one-third or more of each square. The number of squares remaining without peeling (remaining number) is measured, and the number of peeling with respect to the total number of squares (100 pieces) is used as an index of adhesion.
In the optical laminate, durability is important not only in the initial stage immediately after production but also for a long period of time. Therefore, an environmental test was conducted in which the sample was allowed to stand for 500 hours in an environment of a temperature of 85 ° C. and a relative humidity of 85% RH, and the adhesion was similarly evaluated for the sample of the environmental test.
It is preferable that the adhesion is high, and it is desirable that the number of squares remaining without peeling (remaining number) in the cross-hatch method is high.

As is clear from Table 2, in the optical laminates of Examples 1 to 6 in which an aluminum film having a bulk melting point of 660 ° C. is used as the adhesion layer, the total light transmittance changes depending on the film thickness of the adhesion layer. It can be said that the film thickness is 91% or more in the range of 0.5 to 8 nm, which is good. In addition, it can be said that the adhesion at the initial stage and after the environmental test is sufficient. Optical laminates of Examples 7, 8 and 9 in which a zinc film (melting point 420 ° C.), a tin film (232 ° C.) and indium (157 ° C.), which have a lower melting point than an aluminum film, are used as adhesion layers. Also, excellent results were shown in both total light transmittance and adhesion.
The above results show that by using a metal material having a melting point of 700 ° C. or lower, a uniform metal material film is formed on the surface of the resin film when the adhesion layer is formed, and both good optical characteristics and adhesion are achieved. It shows that it can be done.

The optical laminate of Comparative Example 1 that did not form an adhesive layer had a low total light transmittance, because the moisture released from the resin film affected the optical layer and formed a lower oxide. Presumed. Further, it was confirmed that the optical laminate of Comparative Example 1 was inferior in adhesion because peeling was observed even in the initial stage. Therefore, the environmental test was omitted.

The optical laminates of Comparative Examples 2 to 5 having a titanium film having a bulk melting point of 1668 ° C. as an adhesion layer were able to secure the initial adhesion. However, the adhesion after the environmental test was insufficient. Although the adhesion was improved by increasing the film thickness of the adhesion layer, the total light transmittance tended to decrease as the film thickness of the adhesion layer was increased. Therefore, it was not possible to find a condition that achieves both the total light transmittance and the adhesion after the environmental test.

In the optical laminate 10 of Comparative Examples 6 to 7 in which a silver film having a bulk melting point of 962 ° C. was used as an adhesion layer, in Comparative Example 6 in which the thickness of the adhesion layer was 2 nm, both the initial adhesion and the total light transmittance were low. rice field. This is probably because silver tends to aggregate. Therefore, in Comparative Example 6, the environmental test was omitted. On the other hand, in the optical laminate of Comparative Example 7 having a film thickness of 4 nm, the initial adhesion and the total light transmittance were acceptable, but the adhesion after the environmental test was insufficient.

The optical laminates of Comparative Examples 8 to 9 in which a germanium film having a bulk melting point of 938 ° C. was used as an adhesion layer were able to secure the total light transmittance and the initial adhesion. However, the adhesion after the environmental test was low.

The optical laminates of Comparative Examples 10 to 11 having a tungsten film having a bulk melting point of 3422 ° C. as an adhesive layer could secure the total light transmittance. However, in Comparative Example 10 in which the film thickness of the adhesion layer was 2 nm, the initial adhesion was low. Therefore, the environmental test was omitted. Further, in Comparative Example 11 in which the film thickness of the adhesion layer was 4 nm, the adhesion after the environmental test was low.

In Comparative Example 12 in which an indium film having a bulk melting point of 157 ° C. and a thickness of 10 nm was used as an adhesion layer, the total light transmittance was less than 91%. This indicates that the thick adhesion layer has an effect of light absorption, and it is practically disadvantageous if the thickness of the adhesion layer exceeds 8 nm.

As described above, the effect of the present invention could be demonstrated from the results of Examples and Comparative Examples.

10 ... Optical laminate 11 ... Transparent substrate 12 ... Adhesive layer 13 ... Optical layer 13a ... High refractive index layer 13b ... Low refractive index layer

The adhesion layer 12 is a layer that adheres the transparent base material 11 and the optical layer 13.
The adhesion layer 12 is made of a metal material having a melting point of 700 ° C. or lower. The metal material may be a simple substance of metal or an alloy. Examples of the metal material include metals such as Al, Pb, Sn, In, Zn, and Bi. These metals may be alloys containing a single element or a plurality of elements. If it is Al or the like, a natural oxide film is formed, but this natural oxide film is treated as a metal film. When the metal material is an alloy, the melting point of each of the constituent elements contained in the alloy may be 700 ° C. or higher as long as the melting point of the film formed is 700 ° C. or lower. If the film thickness of the adhesion layer 12 is too thin, the layer is not formed and the constituent atoms are localized, which may cause light absorption or impair the adhesion. Therefore, the film thickness of the adhesion layer 12 is preferably 0.5 nm or more. Further, if the film thickness of the adhesion layer 12 exceeds 8 nm, the absorption of light by the adhesion layer 12 becomes remarkable, and the light transmittance of the optical laminate 10 may be impaired. Therefore, the film thickness of the adhesion layer 12 is preferably in the range of 0.5 nm or more and 8 nm or less.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. In addition, Examples 1, 7 and 8 are reference examples.

Claims (6)

An optical laminate having a transparent substrate, an adhesive layer provided on at least one surface of the transparent substrate, and an optical layer provided on the surface of the adhesive layer opposite to the transparent substrate. There,
The adhesion layer is made of a metal material and is made of a metal material.
The thickness of the adhesion layer is 8 nm or less, and the thickness is 8 nm or less.
The metal material is an optical laminate having a melting point in the range of 100 ° C. or higher and 700 ° C. or lower. The optical laminate according to claim 1, wherein the transparent substrate is a resin film. The optical laminate according to claim 1 or 2, wherein the optical layer is an oxide layer. The optical laminate according to any one of claims 1 to 3, wherein the optical layer is an alternating laminate in which high refractive index layers and low refractive index layers are alternately laminated. The optical laminate according to any one of claims 1 to 4, wherein the transmittance of light having a wavelength of 550 nm is 91% or more. An article comprising the optical laminate according to any one of claims 1 to 5.

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