TW202012158A - Cover film and image display device - Google Patents

Abstract

Provided is a cover film that does not impair visibility of an image display apparatus, and that exhibits an excellent texture and design characteristics when an optical monitor is not being used. The cover film comprises a laminated body having: a metal base material with a plurality of through-holes penetrating in a thickness direction; and a resin layer provided on at least one surface of the metal base material. When an average opening ratio of the plurality of through-holes is expressed as G%, 50% < average opening ratio G% ≤ 95%. The plurality of through-holes are random in arrangement position and/or shape, and at least 5% of all the through-holes are in communication with adjacent through-holes.

Description

Cover film and image display device

The invention relates to a cover film and an image display device having the cover film. The cover film is composed of a laminated body having a metal base provided with a plurality of through holes penetrating in the thickness direction and provided on the metal base The resin layer on at least one surface of.

Conventionally, there has been proposed an optical film that is arranged on the object and restricts the field of view or improves light transmittance. Patent Document 1 describes a light-transmitting optical film that is alternately continuous at predetermined intervals so as to have a low refractive index layer and a high refractive index layer inside the film perpendicular to and parallel to the front and back surfaces. In the optical film of Patent Document 1, by totally reflecting the light incident on the optical film at the interface between the low refractive index layer and the high refractive index layer in the film, the direction of the light is changed and transmitted. On the other hand, the Light other than totally reflected light is absorbed and diffused in the low refractive index layer. However, the optical film of Patent Document 1 needs to be alternately continuous and a low-refractive index layer and a high-refractive index layer are provided inside the film, and the structure is complicated.

In contrast, Patent Document 2 describes a composite body capable of obtaining a molded product having a simple structure and excellent appearance and light transmittance. The composite of Patent Document 2 has an aluminum substrate having a plurality of through holes in the thickness direction and a resin layer provided on at least one surface of the aluminum substrate. The average opening diameter of the through holes is 0.1 to 100 μm. The average opening ratio is 1-50%, and the structure is simple. Also, in Patent Document 3, it is composed of a laminate formed by laminating a base material layer and a metal thin film, and when a decorative resin molded product is formed, a metal design is displayed when the light source is turned off, and a light-based design is displayed when the light source is turned on. Transmissive design. [Prior Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-185767 [Patent Literature 2] International Publication No. 2017/150099 [Patent Document 3] Japanese Patent Application Publication No. 2017-189983

The composite body of Patent Document 2 described above can obtain a molded product having excellent appearance and light transmittance. However, when it is currently arranged on an object, further visibility is required for display objects such as characters and pictures displayed on the object. . For example, with regard to visibility, in line and space patterns, it is required to be able to visually recognize thinner line widths and narrower pitches, that is, imaging blur is less. In addition, by adhering these composites in front of the optical monitor, the designability of the optical monitor when not in use can be improved, but there is a problem that the function of the original optical monitor is impaired due to insufficient light transmittance. In the composite material composed of the base material layer and the metal thin film layer of Patent Document 3, there is a problem that the use of a metal thin film having a small amount of light transmission and a degree of light transmission is inferior in texture and cannot improve designability. For example, when a metal vapor-deposited film is provided thinly, although light can be transmitted, the surface is visually recognized like a plastic, and the design is poor.

An object of the present invention is to provide a cover film having excellent design quality without impairing visibility as an image display device and without using an optical monitor.

In order to achieve the above object, the present invention provides a cover film composed of a laminate having a metal substrate provided with a plurality of through holes penetrating in the thickness direction and a resin provided on at least one surface of the metal substrate Layer, in this cover film, when the average opening ratio of the plurality of through holes is G%, it is 50%<average opening ratio G%≤95%, and at least one of the arrangement position and shape of the plurality of through holes is random Yes, at least 5% of all the through holes communicate with the adjacent through holes.

When the thickness of the metal substrate is T μm, the ratio Q represented by the average opening ratio G%/thickness T μm is preferably 1≦Q≦50. The resin layer is preferably provided on each surface of the metal substrate. The resin layer preferably has a total light transmittance of 60% or more in the wavelength range of 380 to 780 nm. The resin layer is preferably made of any one of polyethylene terephthalate, polyethylene, polypropylene, acrylic acid, and polyimide. The average thickness of the resin layer is preferably 12 to 500 μm. The average thickness of the metal substrate is preferably 10 μm or less.

The metal substrate is selected from aluminum, copper, silver, gold, platinum, stainless steel, steel, titanium, tantalum, molybdenum, niobium, zirconium, tungsten, beryllium copper, phosphor bronze, brass, nickel silver, tin, zinc, iron , Nickel, permalloy, nickel-chromium alloy, 42 alloy, kovar alloy, Monel alloy, Inco nickel alloy and Hurst alloy are preferred. In addition, the present invention provides an image display device in which a cover film is provided on an image display surface. [Effect of the invention]

According to the present invention, it is possible to provide a cover film that does not reduce visibility and does not cause interference unevenness such as moire, and can impart design to a screen when an optical monitor is not used. In addition, it is possible to provide an image display device having the above-mentioned cover film.

The cover film and image display device of the present invention will be described in detail based on the preferred embodiments as shown in the attached drawings. In addition, the drawings described below are examples for explaining the present invention, and the present invention is not limited to the drawings shown below. In addition, below, "-" which shows the numerical range includes the numerical value described on both sides. For example, ε is a numerical value α to a numerical value β, and the range of ε includes a numerical value α and a numerical value β, and if expressed by a mathematical symbol, α≦ε≦β. The angles such as “angle expressed by specific numerical value”, “parallel” and “vertical” include the error range generally allowed in the corresponding technical field unless otherwise specified. In addition, "the entire surface" and the like include the error range generally allowed in the corresponding technical field.

1 is a schematic cross-sectional view showing an example of a laminate constituting a cover film according to an embodiment of the present invention, and FIG. 2 is a schematic plan view showing an example of a laminate constituting a cover film according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the laminate constituting the cover film according to the embodiment of the present invention. As shown in FIG. 1, the cover film 10 is composed of a laminate 11, for example. The laminate 11 has a metal base 12 provided with a plurality of through holes 13 penetrating in the thickness direction, and a resin layer 14 provided on the back surface 12b of the metal base 12 via an adhesive layer 15. The metal base 12 is provided with a plurality of substantially circular through holes 13 as shown in FIG. 2, for example. At least 5% of all the through-holes 13 communicate with the adjacent through-hole, that is, more than 5% of all the through-holes 13 communicate with the other through-hole, thereby becoming a non-circular through-hole The hole 13g also constitutes a color pattern.

As described above, the through-holes communicate with the adjacent through-holes, but the number of connected through-holes is not particularly limited, and at least two through-holes may be connected. For example, in FIG. 2, there are plural non-circular through holes 13g, but it may be one. However, from the viewpoint of interference unevenness such as moire, it is preferable to have a plurality of through holes 13g. As described above, the through hole 13g constitutes a color pattern, whereby a unique texture can be formed. Since the non-circular through holes 13g connect the substantially circular through holes as described above, the non-circular refers to a shape in which a plurality of circles are connected and formed by a curve, and there is no angle. Therefore, the non-circle does not include polygons but ellipses. In addition, the case of the through hole 13g is also referred to as a collective through hole. As described above, at least one of the arrangement position and shape of the through holes is random. Moreover, at least 5% of all the through holes communicate with the adjacent through holes, thereby randomly forming non-circular through holes and forming a fine color pattern, which not only does not cause interference unevenness such as moire, And can improve the design of the surface.

The arrangement positions of the through holes are random, which means that the arrangement positions of the through holes have no regularity, that is, have irregularities. The distribution of irregularities can be a normal distribution or a uniform distribution. No regularity means that the arrangement positions of all the through-holes will not be repeatedly indicated by polygonal vertices of the same size. In addition, it means that the arrangement position of all the through holes cannot be represented by a number sequence or a function. The random shape refers to a state in which the ratio S1/S0 of the projected area S1 of the hole in the independent through-hole to the area S0 of the circle whose diameter is the diameter of the hole is 0.1 or more and less than 0.95. In addition, since the distance between the holes is not regular, the shape of the collective through-holes formed by connecting a plurality of holes is also irregular.

The cover film 10, that is, the laminate 11 is disposed on the surface 17 a of the optical monitor 17 toward the resin layer 14, for example. The surface 17a of the optical monitor 17 is an image display surface that displays images such as characters and pictures and animations. When the laminate 11 is viewed from the surface 12a side of the metal base material 12 or the surface side of the resin layer 14, the display objects such as characters and pictures displayed on the surface 17a of the optical monitor 17 can be visually recognized When the surface is close to each other, the image blur and the like are improved and the visibility is excellent. As shown in FIG. 1, when the resin layer 14 is provided on only one side, when bonding to the optical monitor 17, either the metal substrate 12 side or the resin layer 14 side may be bonded.

In order to adhere the cover film to the optical monitor, a transparent adhesive layer can be provided on the cover film side. In order to improve the adhesion workability, a release paper for protecting the adhesive layer can also be provided. The excellent visibility of the optical monitor depends largely on the subjective thoughts of the observer, and its evaluation is completed by the evaluation of a plurality of observers. Since the visibility of the optical monitor is also affected by the brightness and darkness of the screen, when the cover film is used, the brightness of the light source can be finely adjusted during use. The design of the screen of the optical monitor 17 when the optical monitor is not used is also the same, since it largely depends on the subjective thoughts of the observer, and its evaluation is completed by the evaluation of a plurality of observers.

In the laminate 11, when the average opening ratio of the through holes 13 is G (%), it is 50%<average opening ratio G%≤95%. Among them, it is important that the opening portion is composed of a plurality of substantially circular through-holes randomly arranged and adjacent through-holes, that is, non-circular through-holes formed by connecting a plurality of through-holes. As a result, the cover film 10 that does not produce moiré caused by regularly arranged through holes and has a fine color text on the screen when the optical monitor is not used is designed. In addition, it has a fine color pattern composed of non-circular through holes, whereby a texture that cannot be obtained in a metal deposited film can be obtained. In addition, the average aperture ratio G is preferably 55%≦average aperture ratio G(%)≦90%, and 60%≦average aperture ratio G(%)≦85% is more preferably. The opening is a non-circular through hole in which at least 5% of all the through holes made of a plurality of substantially circular through holes provided in the metal film communicate with the adjacent through holes. A non-circular through hole that connects two or more substantially circular through holes accounts for 5% or more of all the through holes, but it is preferably 15% or more, and more preferably 25% or more. Although the upper limit of the proportion of non-circular through-holes connecting two or more substantially circular through-holes is 100%, it is actually difficult to have no independently circular openings, so it is more appropriate to be less than 100%.

In addition, when the thickness of the metal base material 12 is T (μm), the ratio Q (%/μm) expressed by the average opening ratio G (%)/thickness T (μm) is 1≤Q(%/μm)≤ 50 is better, more preferably 20≤Q(%/μm)≤35. When the ratio Q (%/μm) is 1≦Q≦50, the through holes 13 of the metal base material 12 can be suppressed from scattering on the inner wall surface. In addition, the thickness T of the metal substrate 12 is preferably 10 μm or less, and more preferably 5 μm or less. When the thickness T is 10 μm or less, it is possible to reduce the scattering of the through holes 13 of the metal base 12 on the inner wall surface.

The laminate 11 is not limited to the configuration shown in FIG. 1, and the resin layer 14 may be provided on the front surface 12 a of the metal base material 12 instead of the back surface 12 b of the metal base material 12. In addition, the laminate 11 may have a structure in which a resin layer 14 is provided on each surface of the metal base 12. For example, as shown in FIG. 3, the resin layer 14 may be provided on the front surface 12 a and the back surface 12 b of the metal base material 12 via the adhesive layer 15. In this case, the resin layer 14 is disposed on the surface 17a of the optical monitor 17 toward any one. The resin layer 14 is for improving the scratch resistance and workability of the laminate 11. By providing the resin layers 14 on both sides of the metal substrate 12, the metal substrate 12 is protected by the resin layer 14 and cannot directly contact the metal substrate 12, thereby improving scratch resistance due to bending or the like. In addition, in the laminate 11, as long as the resin layer 14 is provided on at least one of the front surface 12 a and the back surface 12 b of the metal base material 12, the adhesive layer 15 is not necessarily required, and it may be a structure without the adhesive layer 15.

Regarding the average aperture ratio G based on the through-holes 13, a parallel light optical unit is provided on one surface side of the metal base material 12 to transmit parallel light, and an optical microscope is used at a magnification of 100 times from the other surface of the metal base material 12 The surface 12a of the metal substrate 12 is enlarged to be photographed, and the surface image of the metal substrate is acquired. The field of view of the obtained surface image of the metal substrate 12 in the range of 10 mm × 10 cm and 100 mm × 75 mm (5 locations), from the opening of the through-hole 13 projected by the transmitted parallel light The ratio of the total area to the area of the visual field (geometric area) was calculated (opening area/geometric area), and the average value in each visual field (five locations) was used as the average aperture ratio. Regarding the substantially circular through holes among the through holes that do not communicate with the adjacent through holes, the aperture ratio is calculated from the observation result of the optical microscope that transmits the same parallel light as described above, and the ratio of the total aperture ratio is obtained.

By using the laminated body 11 as described above, when the laminated body 11 is used for the cover film 10, the visibility can be ensured, and the designability when the optical monitor is not used can be improved. Moreover, the resin layer 14 can easily process a molded article such as a metal decorative body that uses the laminate 11 for lighting purposes, for example.

Hereinafter, the laminate will be described more specifically. [Metal substrate] As long as the metal substrate is a metal containing an alloy, the composition is not particularly limited. The metal substrate is selected from, for example, aluminum, copper, silver, gold, platinum, stainless steel, steel, titanium, tantalum, molybdenum, niobium, zirconium, tungsten, beryllium copper, phosphor bronze, brass, nickel silver, tin, zinc, Metals in the group of iron, nickel, permalloy, nickel-chromium alloy, 42 alloy, kovar alloy, Monel alloy, Inco nickel alloy and Hester alloy.

As the aluminum used for the metal base material, for example, known aluminum alloys such as 1000 series such as 1085, 3000 series such as 3003, and 8000 series such as 8021 can be used. More specifically, as the aluminum alloy, for example, aluminum alloys with alloy numbers shown in Table 1 below can be used.

[Table 1]

＜Thickness＞ The average thickness of the metal substrate is preferably 10 μm or less. The average thickness of the metal substrate is the average of the thicknesses obtained by measuring any 5 points using a contact-type film thickness meter (digital electronic micrometer). In the case of measuring the thickness of the metal substrate in the state of the laminate, after measuring the thickness of the entire laminate with a contact-type film pressure gauge, the metal substrate or resin material can be peeled off and the thickness can be measured. The thickness of the metal substrate is determined by the difference between the thickness of the metal substrate and the metal substrate or resin material.

<Through hole> The average opening diameter of the individual through holes of the through holes of the metal base material is preferably 10 to 50 μm. In particular, it is desirable to connect a plurality of substantially circular through holes to form a plurality of non-circular irregular through holes. The ratio of the non-circular through holes connecting the plurality of through holes must be 5% or more, preferably 15% or more, and more preferably 25% or more as described above with respect to the entire through holes. By this, a fine random color pattern is formed on the surface, and designability can be improved. In addition, as described above, although the upper limit of the ratio of the non-circular through holes connecting the plurality of through holes is 100%, it is actually less than 100%.

[Resin layer] As described above, the resin layer is provided on at least one of the front surface and the back surface of the metal substrate. The resin layer improves the scratch resistance and processability of the laminate. The resin layer is composed of, for example, any one of polyethylene terephthalate, polyethylene, polypropylene, acrylic acid, and polyimide. In addition, the total light transmittance of the resin layer in the wavelength range of 380 to 780 nm is preferably 60% or more. If the above-mentioned total light transmittance is 60% or more, it has light-transmitting applications, for example, it can ensure sufficient visibility when used in a filter, but from the viewpoint of reducing the image blur caused by the haze of the resin, The above total light transmittance is more preferably 80 to 92%. In addition, from the viewpoint of image blur, it is preferable that the resin layer is optically neutral without changing the color tone. Therefore, it is preferable that the value of the light transmittance of the resin layer in the wavelength region of 380 to 780 nm is constant and flat. The total light transmittance can be measured using a spectrophotometer (manufactured by Hitachi, Ltd., U-3000). ＜Thickness＞ From the viewpoint of workability and workability, the average thickness of the resin layer is preferably 12 to 500 μm, more preferably 12 to 250 μm, further preferably 25 to 200 μm, and particularly preferably 50 to 150 μm. The average thickness of the resin layer is the average value of the thickness obtained by measuring any 5 points using a contact-type film thickness meter (digital electronic micrometer).

[Next layer] If the adhesive layer can bond the metal base material and the resin layer, it is not particularly limited, and a known adhesive can be used, and for example, a two-component curable polyurethane adhesive can be used. From the viewpoint of the light transmittance of the entire laminate, the adhesive layer preferably has the same total light transmittance as the metal substrate and the resin layer. In addition, from the viewpoint of imaging blur, it is preferable that the subsequent layer be optically neutral without changing the color tone. Therefore, it is preferable that the value of the light transmittance of the resin layer in the wavelength region of 380 to 780 nm is constant and flat. In addition, as described above, as long as the resin layer can be provided on the metal base material, an adhesive layer is not necessarily required, and there may be no adhesive layer.

Next, a method of manufacturing the laminate constituting the cover film will be described. 4 to 9 are schematic cross-sectional views showing steps of a method of manufacturing a laminate constituting a cover film according to an embodiment of the present invention. First, the metal member 20 to be the metal base 12 is prepared (see FIG. 4 ). The metal member 20 is made of aluminum, for example. Hereinafter, the metal member 20 made of aluminum will be described as an example. As shown in FIG. 4, for example, the adhesive 21 is applied to the back surface 20 b of the metal member 20. Next, the resin layer 14 is adhered to the metal member 20 via the adhesive 21. As shown in FIG. 5, the adhesive 21 is cured as the adhesive layer 15 to obtain a composite 23 of the metal member 20 and the resin layer 14. In addition, the method of providing the resin layer 14 is not particularly limited to the above method. The step of providing the resin layer 14 is referred to as a resin layer forming step, and will be described in detail later.

Next, as shown in FIG. 6, a film forming process is performed on the surface 20 a of the metal member 20 to form an aluminum hydroxide film 24. Regarding the aluminum hydroxide film 24, for example, by performing electrolytic treatment on the metal member 20 as a cathode, the aluminum hydroxide film 24 is formed on the surface 20 a of the metal member 20. The step of forming the aluminum hydroxide film 24 is referred to as a film forming step, and will be described in detail later. Next, as shown in FIG. 7, through holes 13 penetrating the aluminum hydroxide film 24 and the metal member 20 in the thickness direction of the metal member 20 are formed in the aluminum hydroxide film 24 and the metal member 20. The through-hole 13 can be formed using electrolytic dissolution treatment, for example. The step of forming the through hole 13 is referred to as a through hole forming step, and will be described in detail later. Next, the aluminum hydroxide film 24 is dissolved, and as shown in FIG. 8, the aluminum hydroxide film 24 is removed. The step of removing the aluminum hydroxide film 24 is referred to as a film removal step, and will be described in detail later. Next, for example, the through-hole 13 is subjected to an etching process so as to have a predetermined thickness and average opening ratio. Thereby, as shown in FIG. 9, it is possible to obtain the cover film 10 that is the laminate 11 of the metal base material 12 and the resin layer 14 having the plurality of through holes 13.

The method of manufacturing the metal substrate 12 having a plurality of through holes 13 is not limited to the above method. For example, the photolithography method may be used to form a plurality of through holes 13 in the metal member 20 that becomes the metal base material 12 alone, to obtain the metal base material 12 having the plurality of through holes 13 shown in FIG. 10. Next, as shown in FIG. 11, the resin layer 14 is bonded to the back surface 12 b of the metal substrate 12 via the adhesive layer 15 to obtain the cover film 10 that is the laminate 11.

Hereinafter, the method of manufacturing the laminate will be described more specifically. [Method of manufacturing complex] [Film formation step] The film forming step is a step of forming a film of aluminum hydroxide by performing a film forming process on the surface of the aluminum metal substrate as described above.

<Film formation treatment> The above-mentioned film forming process is not particularly limited, and for example, the same process as the conventionally known aluminum hydroxide film forming process can be performed. As the film forming process, for example, the conditions and devices described in paragraphs [0013] to [0026] of JP-A-2011-201123 can be suitably used.

The conditions of the film formation process vary due to the electrolyte used, so it cannot be determined at all, but usually the electrolyte concentration is 1 to 80% by mass, the liquid temperature is 5 to 70°C, the current density is 0.5 to 60 A/dm ² , and the voltage 1 It is preferably -100 V and an electrolysis time of 1 second to 20 minutes, and is adjusted to the desired amount of coating.

As the electrolytic solution, it is preferable to use nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, or oxalic acid, or a mixed acid in which two or more of these acids are mixed for electrochemical treatment. In the case of electrochemical treatment in an electrolytic solution containing nitric acid or hydrochloric acid, direct current or alternating current may be applied between the aluminum substrate and the counter electrode. When direct current is applied to the aluminum substrate, the current density is preferably 1 to 60 A/dm ^{2 and more} preferably 5 to 50 A/dm ² . In the case of performing electrochemical treatment continuously, it is preferable to perform the liquid power supply method by supplying power to the aluminum substrate through the electrolytic solution.

The amount of the aluminum hydroxide film formed by the film forming process is preferably 0.05 to 50 g/m ^{2, and more} preferably 0.1 to 10 g/m ² .

[Steps for forming through holes] The through hole forming step is a step of performing electrolytic dissolution treatment after the film forming step to form a through hole penetrating the aluminum hydroxide film and the metal member.

<Electrolytic Dissolution> The above electrolytic dissolution treatment is not particularly limited, and an acidic solution can be used as an electrolytic solution using direct current or alternating current. Among them, it is preferable to perform electrochemical treatment using at least one acid of nitric acid and hydrochloric acid, and it is more preferable to perform electrochemical treatment using a mixed acid in which at least one acid of sulfuric acid, phosphoric acid, and oxalic acid is added to these acids.

As an electrolytic solution, that is, an acidic solution, in addition to the above-mentioned acids, U.S. Patent No. 4,671,859, U.S. Patent No. 4,661,219, U.S. Patent No. 4,618,405, U.S. Patent No. 4,600,482, U.S. Patent No. 4,566,960, U.S. Patent No. 4,566,958 No. 4, US Pat. No. 4,566,959, US Pat. No. 4,416,972, US Pat. No. 4,374,710, US Pat. No. 4,336,113 and US Pat. No. 4,184,932, the electrolytes described in the specifications.

The concentration of the acidic solution is preferably 0.1 to 2.5% by mass, and 0.2 to 2.0% by mass is particularly preferred. In addition, the liquid temperature of the acidic solution is preferably 20 to 80°C, and more preferably 30 to 60°C.

In addition, as for the aqueous solution mainly composed of the above-mentioned acid, it is possible to add aluminum nitrate, sodium nitrate, ammonium nitrate and other nitrate ions to an aqueous solution of an acid having a concentration of 1 to 100 g/L in a range from 1 g/L to saturation. At least one of hydrochloric acid compounds having hydrochloric acid ions such as nitric acid compounds, aluminum chloride, sodium chloride, and ammonium chloride, and sulfuric acid compounds having sulfuric acid ions such as aluminum sulfate, sodium sulfate, and ammonium sulfate are used. Here, "as the main body" means that the component that becomes the main body in the aqueous solution contains 30% by mass or more, preferably 50% by mass or more, with respect to the entire component added to the aqueous solution. Hereinafter, other components are also the same. Furthermore, metals contained in aluminum alloys such as iron, copper, manganese, nickel, titanium, magnesium, and silicon dioxide may also be dissolved in the aqueous solution containing the above acid as a main component. It is preferable to use a liquid obtained by adding aluminum chloride, aluminum nitrate, aluminum sulfate, and the like in an aqueous solution with an acid concentration of 0.1 to 2% by mass so that aluminum ions become 1 to 100 g/L.

DC current is mainly used in electrochemical dissolution treatment. When AC current is used, the AC power wave is not particularly limited. Sine wave, rectangular wave, trapezoidal wave and triangular wave can be used. Among them, rectangular wave or trapezoidal wave Preferably, the trapezoidal wave is particularly good.

(Nitric acid electrolysis) Electrochemical dissolution treatment using an electrolytic solution containing nitric acid as the main body (hereinafter, also referred to as "nitric acid dissolution treatment") can easily form an average opening diameter of 0.1 μm or more and less than 100 μm Through hole. Among them, from the viewpoint of easy control of the dissolution of through-hole formation, the nitric acid dissolution treatment uses a direct current and is carried out under the condition that the average current density is 5 A/dm ² or more and the electric quantity is 50 C/dm ² or more. Electrolytic treatment is preferred. In addition, the average current density is preferably 100 A/dm ² or less, and the electric quantity is preferably 10000 C/dm ² or less. In addition, the concentration and temperature of the electrolyte in nitric acid electrolysis are not particularly limited, and it is possible to use a nitric acid electrolyte with a high concentration, such as a nitric acid concentration of 15 to 35% by mass, to perform electrolysis at a temperature of 30 to 60°C or to use a nitric acid concentration of 0.7 to 2. The mass% nitric acid electrolyte is electrolyzed at a high temperature, for example, above 80°C. In addition, electrolysis can be performed using an electrolyte solution in which at least one of sulfuric acid, oxalic acid, and phosphoric acid is mixed in the nitric acid electrolyte solution at a concentration of 0.1 to 50% by mass.

(Hydrochloric acid electrolysis) Electrochemical dissolution treatment (hereinafter also referred to as "hydrochloric acid dissolution treatment") using an electrolyte containing hydrochloric acid as the main body can also easily form an average opening diameter of 1 μm or more and less than 100 μm Through holes. Among them, from the viewpoint of easy control of the dissolution of the formation of through-holes, the hydrochloric acid dissolution treatment uses a direct current and is carried out under the condition that the average current density is 5 A/dm ² or more and the electric quantity is 50 C/dm ² or more. Electrolytic treatment is preferred. In addition, the average current density is preferably 100 A/dm ² or less, and the electric quantity is preferably 10000 C/dm ² or less. In addition, the concentration and temperature of the electrolytic solution in hydrochloric acid electrolysis are not particularly limited, and it is possible to perform electrolysis at a temperature of 30 to 60°C using a high concentration hydrochloric acid electrolytic solution having a hydrochloric acid concentration of 10 to 35% by mass or a hydrochloric acid concentration of 0.7 to 2 mass % Of the hydrochloric acid electrolyte is electrolyzed at a high temperature, such as above 80°C. In addition, electrolysis can be performed using an electrolyte solution in which at least one of sulfuric acid, oxalic acid, and phosphoric acid at a concentration of 0.1 to 50% by mass is mixed with the hydrochloric acid electrolyte solution.

[Skin Removal Procedure] The film removal step is a step of performing chemical dissolution treatment to dissolve the aluminum hydroxide film and remove it. The above-mentioned film removal step can remove the aluminum hydroxide film, for example, by performing an acid etching process or an alkali etching process described later.

<Acid etching treatment> The above-mentioned dissolution treatment is a treatment to dissolve the aluminum hydroxide film by using a solution that preferentially dissolves aluminum hydroxide over aluminum (hereinafter, referred to as "aluminum hydroxide solution").

Among them, the aluminum hydroxide solution contains, for example, selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, chromium compounds, zirconium-based compounds, titanium-based compounds, lithium salts, cerium salts, magnesium salts, sodium silicofluoride, and fluorine An aqueous solution made of at least one of the group of zinc compound, manganese compound, molybdenum compound, magnesium compound, barium compound, and halogen monomer is preferable.

Specifically, examples of the chromium compound include chromium (III) oxide and anhydrous chromium (VI) acid. Examples of the zirconium-based compound include ammonium zirconium fluoride, zirconium fluoride, and zirconium chloride. Examples of the titanium compound include titanium oxide and titanium sulfide. Examples of lithium salts include lithium fluoride and lithium chloride. Examples of the cerium salt include cerium fluoride and cerium chloride. Examples of magnesium salts include magnesium sulfide. Examples of manganese compounds include sodium permanganate and calcium permanganate. Examples of the molybdenum compound include sodium molybdate. Examples of the magnesium compound include magnesium fluoride and pentahydrate. Examples of the barium compound include barium oxide, barium acetate, barium carbonate, barium chlorate, barium chloride, barium fluoride, barium iodide, barium lactate, barium oxalate, barium perchlorate, barium selenate, and selenium Barium acid, barium stearate, barium sulfite, barium titanate, barium hydroxide, barium nitrate or such hydrates. Among the above barium compounds, barium oxide, barium acetate and barium carbonate are preferred, and barium oxide is particularly preferred. Examples of halogen monomers include chlorine, fluorine, and bromine.

Among them, the aluminum hydroxide solution is preferably an aqueous solution containing an acid, and examples of the acid include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, and oxalic acid, and a mixture of two or more acids. Among them, it is preferable to use nitric acid as the acid. The acid concentration is preferably 0.01 mol/L or more, more preferably 0.05 mol/L or more, and further preferably 0.1 mol/L or more. The upper limit is not particularly limited, but usually it is preferably 10 mol/L or less, and more preferably 5 mol/L or less.

The dissolution treatment is performed by bringing the aluminum substrate on which the aluminum hydroxide film is formed into contact with the above-mentioned dissolution solution. The method of contact is not particularly limited, and examples thereof include a dipping method and a spray method. Among them, the spray method is preferred.

The spray method is an advantageous method when the through holes are continuously formed, and the time for applying the liquid by spray can be determined by the treatment length and the conveying speed. The spray method can supply fresh liquid to the reaction interface, so it can be effectively processed. The spray treatment time is preferably 1 second or more and within 30 minutes, and more preferably 2 seconds or more and within 20 minutes.

<etching treatment> The etching process is, for example, an alkali etching process in which the aluminum hydroxide film is brought into contact with an alkali solution to dissolve the surface layer.

Examples of the alkali used in the alkali solution include caustic alkali and alkali metal salts. Specifically, examples of the caustic alkali include sodium hydroxide (caustic soda) and caustic potassium. In addition, examples of the alkali metal salts include alkali metal silicates such as sodium metasilicate, sodium silicate, potassium metasilicate, and potassium silicate; alkali metal carbonates such as sodium carbonate and potassium carbonate; sodium aluminate, Alkali metal aluminates such as potassium aluminate; alkali metal aldonic acid salts such as sodium gluconate and potassium gluconate; alkali metal hydrogen phosphates such as disodium hydrogen phosphate, dipotassium hydrogen phosphate, sodium phosphate and potassium phosphate. Among them, a caustic alkali solution and a solution containing both caustic alkali and alkali metal aluminate are preferred from the viewpoint of fast etching speed and low cost. In particular, an aqueous solution of sodium hydroxide is preferred.

The concentration of the alkaline solution is preferably 0.1 to 50% by mass, and more preferably 0.2 to 10% by mass. When aluminum ions are dissolved in the alkaline solution, the concentration of aluminum ions is preferably 0.01 to 10% by mass, and more preferably 0.1 to 3% by mass. The temperature of the alkali solution is preferably 10 to 90°C. The processing time is preferably 1 to 120 seconds.

As a method of contacting the aluminum hydroxide film with the alkaline solution, for example, a method of passing the aluminum substrate formed with the aluminum hydroxide film in a tank into which the alkaline solution is added, and making the aluminum base formed with the aluminum hydroxide film The method of immersing the material in the tank into which the alkaline solution is added, and the method of spraying the alkaline solution onto the surface of the aluminum substrate (aluminum hydroxide film) on which the aluminum hydroxide film is formed.

[Resin layer forming step] The resin layer forming step is a step of providing the resin layer on a metal member that does not have through holes. The method of forming the resin layer is not particularly limited, but examples thereof include dry lamination, wet lamination, extrusion lamination, and air lamination. As the dry lamination method, for example, the conditions and devices described in paragraphs [0067] to [0078] of JP-A-2013-121673 can be suitably used.

[Cover film] The laminate formed by the above method can be used as a cover film. Regarding the mounting of the cover film on the optical monitor, the adhesive layer or the adhesive layer can be assembled by using a transparent double-sided adhesive or assembling the optical monitor. For the cover film to be mounted on the optical monitor, in addition to the above, for example, optically transparent adhesives (OCA, Optical Clear Adhesive: optical clear adhesive) and UV (Ultra Violet: ultraviolet ray) hardening resins and other optically transparent resins ( OCR, Optical Clear Resin: optically clear resin). As a commercially available product, for example, a graphic film IJ8150 (product number) manufactured by Sumitomo 3M Limited can be used. In addition, when the outermost surface of the cover film is made of metal, in order to prevent scratches on the metal surface, a commercially available protective film may be bonded. As a commercially available protective film, for example, an overlaminate film IJ4176 (product number) manufactured by Sumitomo 3M Limited can be used. An optical monitor refers to a display device that has an image display surface that displays images and animations such as text and pictures using light transmission or reflection, such as a liquid crystal display device or an organic EL (Organic electro luminescence) display device or uses The projection part of the head-up display and the beam splitter surface for the aerial display of these display devices are also included in the optical monitor.

[Image display device] The image display device is one in which the aforementioned cover film is provided on the image display surface. By assembling the cover film on the image display surface, it is possible to improve the design of the screen when the image display device is not used, that is, the design of the screen when the power is turned off, without reducing the visibility when the image is displayed.

The present invention is basically constructed as described above. The cover film and image display device of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiment, and of course various improvements or changes can be made without departing from the gist of the present invention. [Example]

The characteristics of the present invention will be further specifically described below with examples. The materials, reagents, usage amounts, material quality, ratio, processing contents, processing steps, etc. shown in the following examples can be appropriately changed as long as they do not depart from the gist of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the specific examples shown below. In this example, the laminates of Examples 1 to 5 and Comparative Examples 1 to 4 were made into cover films. For the laminates of Examples 1 to 5 and Comparative Examples 1 to 4, the figures The visibility of the image, the design of the screen when no image was displayed, and the scratch resistance were evaluated. Also, in Comparative Example 5 used as a criterion for evaluation, the visibility of the image, the design of the screen when the image was not displayed, and the scratch resistance were also evaluated. The results are shown in Table 3 below. In addition, the visibility of the image and the design of the screen when the image is not displayed are described below.

<Evaluation of image visibility> 5 types of cover films equivalent to the examples (Examples 1 to 5) and 4 types of cover films corresponding to the comparative examples (Comparative Examples 1 to 4) were used, and they were adhered to the image display device and received by 10 The sensory evaluation of the testers was compared when the cover film was not used. For the image display device, a 24-inch liquid crystal display manufactured by Dell Inc. was used. Regarding the evaluation, the illuminance of the display was evaluated with three levels of standard, illuminance increased by 10%, and illuminance increased by 20%. In addition, the evaluation of the visibility of the image was evaluated by the evaluation criteria shown below. Table 2 shows the structures of Examples 1 to 5 and Comparative Examples 1 to 5. In addition, in Table 2, "-" means none.

Evaluation criteria for evaluation of image visibility Image visibility relative to the standard of display illumination without the cover film (Comparative Example 5) 4: 5 to 10 people evaluated as insignificant 3: 3 to 4 people evaluated as insignificant 2: 1 or 2 people evaluated as insignificant 1: 0 people are evaluated as insignificant

<Texture when the monitor is turned off> As shown in Table 2, 5 types of cover films corresponding to the examples (Examples 1 to 5) and 4 types of cover films corresponding to the comparative examples (Comparative Examples 1 to 4) were bonded to the image display device, respectively. The texture when the monitor is turned off is compared with when the cover film is not used. Whether or not the screen when the cover film was not used was black compared to the texture when the cover film was adhered was evaluated by the sensory based on 10 subjects in the same way as the visibility evaluation of the image. The evaluation items are texture and surface uniformity. In addition, the evaluation of the texture when the display was turned off was evaluated according to the evaluation criteria shown below. Table 3 shows the evaluation results of the visibility of the image and the texture when the display is turned off. In addition, the color of the "features of appearance" in Table 3 was evaluated based on the sensory of 10 subjects in the same manner as the evaluation of the visibility of the image.

Evaluation criteria for evaluation of texture when the monitor is turned off 4: 5 to 10 people rated as good 3: 3 to 4 people rated as good 2: 1 to 2 people rated as good 1: 0 people are evaluated as good

[Table 2]

Hereinafter, Examples 1 to 5 and Comparative Examples 1 to 5 will be described. (Example 1) The laminate of Example 1 will be described. <Fabrication of laminates> As a metal substrate, an aluminum foil of 100 mm square size (manufactured by UACJ Corporation, alloy number 1N30, thickness 9 μm) was prepared. In addition, a two-component hardenable polyurethane adhesive (manufactured by Sanyu REC. LTD., SU3600A and SU3600B) was weighed so that the mass ratio became 30:100, and the solid content concentration was prepared by dissolving these in ethyl acetate. 30% by mass of the adhesive coating liquid. Apply an adhesive layer coating solution to the above aluminum foil, and adhere a 100 mm square PET film with a thickness of 125 μm (TOYOBO CO., LTD., COMOSHINE (registered trademark) A4100 (single-sided easy adhesive layer) that constitutes the resin layer , Thickness 125 μm). The drying temperature was 70° C. and a drying time of 1 minute was allowed to harden to produce a composite material of aluminum foil and resin layer. The thickness of the adhesive at this time was 3 μm.

(Through-hole treatment) Aluminum hydroxide film formation process (film formation step) Electrolysis is carried out using an electrolytic solution maintained at a temperature of 50°C (nitric acid concentration 1%, sulfuric acid concentration 0.2%, aluminum concentration 0.5%), using the above aluminum foil as a cathode, and performing electrolysis Treatment to form an aluminum hydroxide film on the aluminum foil. In addition, electrolysis was performed under DC power. Set the DC current density to 33 A/dm ² and the electricity to 400 C/dm ² . After the aluminum hydroxide film was formed, spray-based water washing was performed. The cross-section cut by the focused ion beam (FIB) cutting process was observed by a scanning electron microscope (SEM) and the thickness of the aluminum hydroxide film was measured to be 1 μm.

Electrolytic dissolution treatment (through-hole formation step) Next, using an electrolytic solution maintained at 50°C (nitric acid concentration 1%, sulfuric acid concentration 0.2%, aluminum concentration 0.5%), using aluminum foil as the anode and setting the current density to 40 A/ dm ² , electrolytic treatment is carried out under the condition that the total amount of electric power is 400 C/dm ² to form a through hole penetrating through the aluminum foil and aluminum hydroxide film. In addition, electrolysis was performed under DC power. After the through-holes were formed, spray-based water washing was performed to dry the aluminum foil. Aluminum hydroxide film removal treatment (film removal step) Next, the aluminum foil after electrolytic dissolution treatment was immersed in an aqueous solution (liquid temperature 35° C.) of 5 mass% sodium hydroxide concentration and 0.5 mass% aluminum ion for 30 seconds. Immersed in an aqueous solution (liquid temperature 50°C) with a sulfuric acid concentration of 30% and an aluminum ion concentration of 0.5% by mass for 20 seconds to dissolve and remove the aluminum hydroxide film. Then, water spray by spraying was performed and the aluminum foil was dried, thereby obtaining an aluminum foil having through holes.

(Alkali etching step) An aqueous solution with a sodium hydroxide concentration of 5 mass% and an aluminum ion concentration of 1 mass% was used for etching at a temperature of 50° C. so that the composite of the aluminum foil and the resin layer had a predetermined thickness and average aperture ratio. The time is set to 500 seconds. By this, a laminated body of an aluminum foil having a through hole and a resin layer was obtained.

(Example 2) Example 2 is the same as Example 1 except that the immersion time in the alkali etching treatment of the composite of the aluminum foil and the resin layer is 400 seconds, as compared to Example 1. (Example 3) Regarding Example 3, compared with Example 1, the immersion time in the alkali etching treatment of the composite of the aluminum foil and the resin layer was 370 seconds, and it was the same as Example 1 except that the immersion time was 370 seconds. (Example 4) Example 4 is the same as Example 1 except that the immersion time in the alkali etching process of the composite of the aluminum foil and the resin layer is 330 seconds, as compared with Example 1. (Example 5) Example 5 is the same as Example 1 except that the immersion time in the alkaline etching process of the composite of the aluminum foil and the resin layer is 200 seconds, compared to Example 1.

(Comparative example 1) Regarding Comparative Example 1, as compared with Example 1, the immersion time in the alkali etching treatment of the composite of the aluminum foil and the resin layer was 150 seconds, and it was the same as Example 1 except that the immersion time was 150 seconds. (Comparative example 2) Regarding Comparative Example 2, as compared with Example 1, the immersion time in the alkaline etching treatment of the composite of the aluminum foil and the resin layer was set to 100 seconds, and it was the same as Example 1 except that the immersion time was 100 seconds. (Comparative example 3) Regarding Comparative Example 3, a single-sided vapor deposition of a PET film (manufactured by TOYOBO CO., LTD., COMOSHINE (registered trademark) A4100 (single-sided easy adhesion layer)) with a thickness of 125 μm so that the light transmittance becomes 30% aluminum. (Comparative example 4) For Comparative Example 4, a commercially available mechanical narrow-hole foil (opening diameter 300 μm, opening ratio 50%, thickness 20 μm) was used directly. (Comparative example 5) Comparative Example 5 is an example in which no cover film is used. Therefore, there is no manufacturing process for the laminate. In addition, as described above, Comparative Example 5 was used as a criterion for evaluation.

[table 3]

As shown in Table 3, Examples 1 to 5 have no cover film compared to Comparative Example 5, that is, many subjects were evaluated as having good texture. In addition, regarding the visibility of the display, it is known that the difference between Example 1 and the absence of the cover film (Comparative Example 5) is relatively small. In Examples 2 to 4, the increase in the illuminance of the display is recognized as The number of subjects without the difference in the cover film (Comparative Example 5) was reduced. On the other hand, it is known that Comparative Example 1 and Comparative Example 2 are laminates having a structure close to the examples, but even if the illuminance of the display is increased, the visibility is hardly improved. In addition, in Comparative Example 1 and Comparative Example 2, the texture evaluation was slightly inferior to that in the Example. However, the reason is that the number of through holes is small and the fine color pattern in the Example is hardly seen. In Comparative Example 3, a silver appearance having a glossy feeling like a half mirror is shown by aluminum vapor deposition, but it has an appearance like a plate like a mirror, so the evaluation of texture is not high. Since there is no fine color pattern, there are few subjects who are evaluated as slight deformation when the cover film is adhered and the surface uniformity is also good. In Comparative Example 4, since the regularly arranged through-holes were seen themselves, there was no subject whose video visibility was not related to the illuminance of the display and was evaluated as insignificant. Regarding texture, the uniformity is not bad, but the evaluation of texture is not too high. FIG. 12 shows a light-transmitting image based on an optical microscope when a cover film having a plurality of through holes is formed.

10: Cover film 11: laminate 12: Metal substrate 12a, 17a, 20a: surface 12b, 20b: back 13, 13g: through hole 14: resin layer 15: then layer 17: Optical monitor 20: Metal components 21: Adhesive 23: Composite 24: aluminum hydroxide coating T: thickness

FIG. 1 is a schematic cross-sectional view showing an example of a laminate constituting a cover film according to an embodiment of the present invention. FIG. 2 is a schematic plan view showing an example of a laminate constituting a cover film according to an embodiment of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the laminate constituting the cover film according to the embodiment of the present invention. 4 is a schematic cross-sectional view showing one step of a method of manufacturing a laminate that constitutes a cover film according to an embodiment of the present invention. 5 is a schematic cross-sectional view showing one step of a method of manufacturing a laminate that constitutes a cover film according to an embodiment of the present invention. 6 is a schematic cross-sectional view showing one step of a method of manufacturing a laminate that constitutes a cover film according to an embodiment of the present invention. 7 is a schematic cross-sectional view showing one step of a method of manufacturing a laminate that constitutes a cover film according to an embodiment of the present invention. FIG. 8 is a schematic cross-sectional view showing one step of the method of manufacturing the laminate constituting the cover film according to the embodiment of the present invention. 9 is a schematic cross-sectional view showing one step of a method of manufacturing a laminate that constitutes a cover film according to an embodiment of the present invention. 10 is a schematic cross-sectional view showing one step of another example of the method for manufacturing a laminate that constitutes a cover film according to an embodiment of the present invention. 11 is a schematic cross-sectional view showing one step of another example of a method of manufacturing a laminate that constitutes a cover film according to an embodiment of the present invention. 12 is a schematic diagram showing a light-transmitting image based on an optical microscope of a cover film formed with a plurality of through-holes.

10: Cover film

11: laminate

12: Metal substrate

13, 13g: through hole

Claims (10)

A cover film composed of a laminated body having a metal substrate provided with a plurality of through holes penetrating in the thickness direction and a resin layer provided on at least one surface of the metal substrate, in the cover film, When the average opening ratio of the plurality of through-holes is G%, it is 50%<average opening ratio G%≤95%, At least one of the arrangement positions and shapes of the plurality of through holes is random, and at least 5% of the through holes in all the through holes communicate with the adjacent through holes. The cover film as described in item 1 of the patent application scope, in which When the thickness of the metal base material is T μm, the ratio Q represented by the average opening ratio G%/the thickness T μm is 1≦Q≦50. The cover film as described in item 1 of the patent application scope, in which The resin layer is provided on each surface of the metal substrate. The cover film as described in item 2 of the patent application scope, in which The resin layer is provided on each surface of the metal substrate. The cover film as described in any one of patent application items 1 to 4, wherein The total light transmittance of the resin layer in the wavelength range of 380 to 780 nm is 60% or more. The cover film as described in any one of patent application items 1 to 4, wherein The resin layer is composed of any one of polyethylene terephthalate, polyethylene, polypropylene, acrylic acid, and polyimide. The cover film as described in any one of patent application items 1 to 4, wherein The average thickness of the resin layer is 12 to 500 μm. The cover film as described in any one of patent application items 1 to 4, wherein The average thickness of the metal substrate is 10 μm or less. The cover film as described in any one of patent application items 1 to 4, wherein The metal substrate is selected from aluminum, copper, silver, gold, platinum, stainless steel, steel, titanium, tantalum, molybdenum, niobium, zirconium, tungsten, beryllium copper, phosphor bronze, brass, nickel silver, tin, zinc, Metals in the group of iron, nickel, permalloy, nickel-chromium alloy, 42 alloy, kovar alloy, Monel alloy, Inco nickel alloy and Hester alloy. An image display device in which a cover film as described in any one of claims 1 to 9 is provided on an image display surface.

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