CN112638643A

CN112638643A - Cover film and image display device

Info

Publication number: CN112638643A
Application number: CN201980055707.3A
Authority: CN
Inventors: 泽田宏和
Original assignee: Fujifilm Corp
Current assignee: Fujifilm Corp
Priority date: 2018-08-29
Filing date: 2019-07-26
Publication date: 2021-04-09
Also published as: TW202012158A; WO2020044900A1; JPWO2020044900A1

Abstract

The invention provides a cover film which does not damage the visibility of an image display device and has excellent design when an optical monitor is not used. The cover film is composed of a laminate having a metal base 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 base. When the average opening ratio of the plurality of through-holes is G%, the average opening ratio is 50% < G% < 95%. At least one of the arrangement positions and the shapes of the through holes is random, and at least 5% of all the through holes are communicated with the adjacent through holes.

Description

Cover film and image display device

Technical Field

The present invention relates to a cover film and an image display device having the cover film, wherein the cover film is composed of a laminate having a metal base provided 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.

Background

Conventionally, an optical film that is disposed on an object and limits a visual field or improves light transmittance has been proposed.

Patent document 1 describes a light-transmitting optical film having a low refractive index layer and a high refractive index layer inside the film, the low refractive index layer and the high refractive index layer being alternately continuous at predetermined intervals so as to be perpendicular to and parallel to the front surface and the back surface. In the optical film of patent document 1, light incident on the optical film is totally reflected at an interface between a low refractive index layer and a high refractive index layer in the film, so that the direction of the light is changed and the light is transmitted, while light other than the totally reflected light is absorbed and diffused in the low refractive index layer. However, the optical film of patent document 1 has a complicated structure because it requires low refractive index layers and high refractive index layers to be alternately and continuously provided inside the film.

On the other hand, patent document 2 describes a composite body that can provide a molded article having a simple structure and excellent appearance and light transmittance. The composite disclosed in patent document 2 has an aluminum base material having a plurality of through holes in the thickness direction and a resin layer provided on at least one surface of the aluminum base material, wherein the through holes have an average opening diameter of 0.1 to 100 μm and an average opening ratio of 1 to 50% based on the through holes, and has a simple structure.

Further, in patent document 3, when a decorative resin molded article is formed from a laminate in which a base material layer and a metal thin film layer are laminated, a design of a metal color tone is displayed when a light source is turned off, and a design based on transmitted light is displayed when the light source is turned on.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 2008-185767

Patent document 2: international publication No. 2017/150099

Patent document 3: japanese patent laid-open publication No. 2017-189983

Disclosure of Invention

Technical problem to be solved by the invention

Although the composite of patent document 2 can provide a molded article having excellent appearance and light transmittance, it is required to have further visibility of a display object such as characters and pictures displayed on the object when the composite is disposed on the object. For example, regarding visibility, in a pattern of lines and spaces, a thinner line width and a narrower pitch are required to be visually recognized, that is, less image-forming die-burn is required.

Further, although the design of the optical monitor can be improved when not in use by attaching these composites to the front surface of the optical monitor, there is a problem that the original function of the optical monitor is impaired due to insufficient light transmittance.

The composite material of patent document 3, which is composed of a base material layer and a metal thin film layer, has a problem that the use of a metal thin film having a small light transmission amount and a high degree of light transmission causes poor texture and fails to improve design. For example, when a thin metal deposition film is provided, light can be transmitted, but the surface is visually recognized as if it is made of plastic, and the design is poor.

The invention aims to provide a cover film which does not damage the visibility of an image display device and has excellent design quality when an optical monitor is not used.

Means for solving the technical problem

In order to achieve the above object, the present invention provides a coating film comprising a laminate having a metal base material provided 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, wherein when an average opening ratio of the plurality of through-holes is G%, the average opening ratio is 50% < G% < 95%, at least one of the arrangement positions and shapes of the plurality of through-holes is random, and at least 5% of all the through-holes communicate with adjacent through-holes.

When the thickness of the metal base material is T [ mu ] m, the ratio Q represented by the average aperture ratio G%/thickness T [ mu ] m is preferably 1. ltoreq. Q.ltoreq.50.

The resin layer is preferably provided on each surface of the metal base material.

The total light transmittance of the resin layer in a wavelength region of 380-780 nm is preferably 60% or more.

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 base material is preferably 10 μm or less.

The metal substrate is preferably composed of a metal selected from the group consisting of aluminum, copper, silver, gold, platinum, stainless steel, titanium, tantalum, molybdenum, niobium, zirconium, tungsten, beryllium copper, phosphor bronze, brass, nickel silver, tin, zinc, iron, nickel, permalloy, nichrome, 42 alloy, kovar, monel, inconel, and hastelloy.

The present invention also provides an image display device in which a cover film is provided on an image display surface.

Effects of the invention

The present invention can provide a cover film that does not reduce visibility, does not generate interference fringes such as moire fringes, and can provide design properties to a screen when an optical monitor is not used. In addition, an image display device having the cover film can be provided.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of a laminate constituting a coverlay according to an embodiment of the present invention.

Fig. 2 is a schematic plan view showing an example of a laminate constituting the coverlay according to the embodiment of the present invention.

Fig. 3 is a schematic cross-sectional view showing another example of the laminate constituting the coverlay according to the embodiment of the present invention.

Fig. 4 is a schematic cross-sectional view showing one step of the method for producing a laminate including a coverlay according to the embodiment of the present invention.

Fig. 5 is a schematic cross-sectional view showing one step of the method for producing a laminate constituting a coverlay according to the embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view showing one step of the method for producing a laminate constituting a coverlay according to the embodiment of the present invention.

Fig. 7 is a schematic cross-sectional view showing one step of the method for producing a laminate constituting a coverlay according to the embodiment of the present invention.

Fig. 8 is a schematic cross-sectional view showing one step of the method for producing a laminate including a coverlay according to the embodiment of the present invention.

Fig. 9 is a schematic cross-sectional view showing one step of the method for producing a laminate including a coverlay according to the embodiment of the present invention.

Fig. 10 is a schematic cross-sectional view showing a step of another example of the method for producing a laminate including a coverlay according to the embodiment of the present invention.

Fig. 11 is a schematic cross-sectional view showing a step of another example of the method for producing a laminate including a coverlay according to the embodiment of the present invention.

Fig. 12 is a schematic view showing a light-transmitting image when the cover film having a plurality of through holes formed in sets is observed with an optical microscope.

Detailed Description

Hereinafter, the cover film and the image display device of the present invention will be described in detail based on preferred embodiments shown in the drawings.

The drawings described below are illustrative diagrams for explaining the present invention, and the present invention is not limited to the drawings described below.

In the following, "to" indicating a numerical range includes numerical values described on both sides. For example, the term "epsilon" is a range from a numerical value α to a numerical value β, and means that the range of epsilon includes the numerical value α and the numerical value β, and when expressed by a mathematical symbol, α ≦ epsilon ≦ β.

The terms "angle represented by a specific numerical value", "parallel" and "perpendicular" include an error range that is usually allowed in the corresponding technical field unless otherwise specified.

And "the entire surface" and the like include an error range generally allowed in the corresponding technical field.

Fig. 1 is a schematic cross-sectional view showing an example of a laminate constituting a coverlay according to an embodiment of the present invention, and fig. 2 is a schematic plan view showing an example of a laminate constituting a coverlay according to an embodiment of the present invention. Fig. 3 is a schematic cross-sectional view showing another example of the laminate constituting the coverlay according to the embodiment of the present invention.

As shown in fig. 1, the cover film 10 is composed of, for example, a laminate 11. The laminate 11 has: a metal base material 12 provided with a plurality of through holes 13 penetrating in a thickness direction; and a resin layer 14 provided on the back surface 12b of the metal base 12 via an adhesive layer 15. As shown in fig. 2, for example, a plurality of substantially circular through holes 13 are provided in the metal base material 12. 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 another through-hole, thereby forming non-circular through-holes 13g and constituting a color pattern.

As described above, the through-holes communicate with the adjacent through-holes, but the number of the through-holes communicating with each other is not particularly limited, and at least two through-holes may communicate with each other.

For example, although a plurality of non-circular through holes 13g are present in fig. 2, the number may be 1. However, it is preferable that the through-holes 13g are present in a plurality from the viewpoint of occurrence of interference fringes such as moire fringes. As described above, the through-holes 13g constitute a color pattern, thereby enabling a unique texture to be formed. Since the non-circular through-hole 13g is formed by connecting substantially circular through-holes as described above, the non-circular shape is a shape formed by curves connected by a plurality of circles, and has no angle. Therefore, the non-circular shape does not include a polygon but includes an ellipse or the like. The through-hole 13g is also referred to as a collective through-hole.

As described above, at least one of the arrangement position and the shape of the through-hole is random. Further, at least 5% of all the through-holes communicate with the adjacent through-holes, whereby non-circular through-holes are randomly formed to form a fine color pattern, and not only interference fringes such as moire fringes are not generated, but also the design of the surface can be improved.

The random arrangement position of the through-holes means that the arrangement position of the through-holes has no regularity, that is, has irregularity. The distribution of irregularities may be normal distribution or uniform distribution. The lack of regularity means that the arrangement positions of all the through-holes are not represented by the repetition of polygonal vertices of the same size. The term "arrangement positions of all through-holes" means that the arrangement positions cannot be expressed by a number series or a function.

The random shape means that the ratio S1/S0 of the projected area S1 of the hole to the area S0 of a circle when the major axis of the hole is defined as the diameter is 0.1 or more and less than 0.95 for the independent through-hole. In addition, since the distances between the individual holes are not regular, the shape of the collective through-hole formed by connecting the plurality of holes is also not regular.

The cover film 10, i.e., the laminate 11, is disposed on the surface 17a of the optical monitor 17, for example, facing the resin layer 14. The surface 17a of the optical monitor 17 is an image display surface on which images such as characters and pictures, and moving images are displayed.

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, a display object such as characters and pictures displayed on the surface 17a of the optical monitor 17 can be visually recognized, and when the laminate 11 is brought into close contact with the surface of the optical monitor 17, the visibility is improved such as the image sticking. As shown in fig. 1, when the resin layer 14 is provided only on one side, either the metal base material 12 side or the resin layer 14 side may be attached when the optical monitor 17 is attached.

In order to attach the cover film to the optical monitor, a transparent adhesive layer may be provided on the cover film side. In order to improve the adhesion workability, a release paper for protecting the adhesive layer may be provided.

Since the excellent visibility of an optical monitor greatly depends on the subjectivity of an observer, the evaluation is performed 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, the brightness of the light source can be finely adjusted even when the cover film is used.

Similarly, the design of the screen of the optical monitor 17 when the optical monitor is not used also greatly depends on the subjectivity of the observer, and therefore, the evaluation is performed by the evaluation of a plurality of observers.

In the laminate 11, the average opening ratio of the through-holes 13 is set to G (%), 50% < the average opening ratio G% < 95%. Here, it is important that the opening portion is formed by a plurality of substantially circular through-holes arranged at random and communicating with the adjacent through-holes, that is, the opening portion is formed by a non-circular through-hole formed by connecting a plurality of through-holes. Thus, the cover film 10 in which the fine color text is formed on the screen when the optical monitor is not used has design properties, while no moire is generated due to the regularly arranged through holes. Further, by having a fine color pattern composed of a non-circular through hole, a texture which cannot be obtained with a metal vapor deposition film can be obtained.

The average opening ratio G is preferably 55% to 90%, more preferably 60% to 85%.

The opening is a non-circular through-hole formed by a plurality of substantially circular through-holes provided in the metal film, and at least 5% of all the through-holes communicate with adjacent through-holes. The non-circular through-holes formed by connecting two or more substantially circular through-holes account for 5% or more of all the through-holes, but are preferably 15% or more, and more preferably 25% or more. The upper limit of the proportion of the non-circular through-holes formed by connecting two or more substantially circular through-holes is 100%, but actually, it is difficult to completely eliminate the independent circular opening, and therefore, it is appropriate that the proportion is less than 100%.

When the thickness of the metal base material 12 is T (μm), the ratio Q (%/μm) expressed as the average opening ratio G (%)/thickness T (μm) is preferably 1 or less Q (%/μm) or more 50 or less, more preferably 20 or less Q (%/μm) or more 35 or less. When the ratio Q (%/μm) is 1. ltoreq. Q.ltoreq.50, scattering on the inner wall surfaces of the through-holes 13 of the metal base material 12 can be suppressed.

The thickness T of the metal base material 12 is preferably 10 μm or less, and more preferably 5 μm or less. When the thickness T is 10 μm or less, scattering on the inner wall surface of the through-hole 13 of the metal base material 12 can be reduced.

The laminate 11 is not limited to the structure shown in fig. 1, and may be a structure in which the resin layer 14 is provided on the front surface 12a of the metal base 12, instead of the structure in which the resin layer 14 is provided on the rear surface 12b of the metal base 12. The laminate 11 may have a structure in which the resin layers 14 are provided on the respective surfaces of the metal base 12. For example, as shown in fig. 3, the resin layer 14 may be provided on the front surface 12a and the back surface 12b of the metal base 12 via the adhesive layer 15. In this case, the resin layer is disposed on the surface 17a of the optical monitor 17 facing any one of the resin layers 14. The resin layer 14 can improve the scratch resistance and the processability of the laminate 11. By providing the resin layers 14 on both sides of the metal base 12, the metal base 12 is protected by the resin layers 14 and does not directly contact the metal base 12, and therefore, scratch resistance due to bending or the like is improved.

In the laminate 11, the adhesive layer 15 is not essential as long as the resin layer 14 can be provided on at least one of the front surface 12a and the back surface 12b of the metal base 12, and the adhesive layer 15 may not be provided.

As for 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, parallel light is transmitted, and the surface 12a of the metal base material 12 is magnified from the other surface of the metal base material 12 at a magnification of 100 times using an optical microscope to take an image, thereby obtaining a surface image of the metal base material. Regarding the fields of view (5 portions) of 100mm × 75mm within the range of 10cm × 10cm of the surface image of the metal base material 12 obtained, a ratio (opening area/geometric area) was calculated from the total of the opening areas of the through-holes 13 projected by the transmitted parallel light and the area (geometric area) of the fields of view, and the average value in each field of view (5 portions) was calculated as the average aperture ratio.

Of the through holes, the substantially circular through holes that do not communicate with the adjacent through holes were calculated from the observation results of the optical microscope that transmitted the same parallel light as described above, and the ratio of the aperture ratio to the total aperture ratio was obtained.

By configuring the laminate 11 as described above, when the laminate 11 is used for the cover film 10, visibility can be ensured, and design properties can be improved when the optical monitor is not used.

Further, the resin layer 14 can easily process the laminate 11 into a molded article such as a metal decorative body for illumination.

Next, the laminate will be described in more detail.

[ Metal base Material ]

The composition of the metal substrate is not particularly limited as long as it is a metal containing an alloy. The metal substrate is made of, for example, a metal selected from the group consisting of aluminum, copper, silver, gold, platinum, stainless steel, titanium, tantalum, molybdenum, niobium, zirconium, tungsten, beryllium copper, phosphor bronze, brass, nickel silver, tin, zinc, iron, nickel, permalloy, nichrome, 42 Alloy (Alloy 42), kovar, monel, inconel, and hastelloy.

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

[ Table 1]

< thickness >

The average thickness of the metal base material is preferably 10 μm or less.

The average thickness of the metal substrate is an average value of thicknesses measured at any 5 points using a contact film thickness meter (digital electronic micrometer). When the thickness of the metal base material in the state of the laminate is measured, the thickness of the entire laminate is measured by a contact type film gauge, and the thickness of the metal base material is measured by peeling the metal base material or the resin material, and the thickness of the metal base material is determined from the difference between the thickness of the entire laminate and the metal base material or the resin material.

< through-hole >

As for the through-holes of the metal base material, the average opening diameter of the individual through-holes is preferably 10 to 50 μm. In particular, it is desirable to form a plurality of non-circular irregular through-holes by connecting a plurality of substantially circular through-holes. The proportion of the non-circular through-holes formed by connecting the plurality of through-holes must be 5% or more, preferably 15% or more, and more preferably 25% or more, as described above, relative to the entire through-holes. This can form a fine color pattern having a random shape on the surface, thereby improving the design. As described above, the upper limit of the proportion of the non-circular through-holes formed by connecting the plurality of through-holes is 100%, but actually, it is appropriate that the proportion is 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 base material. The resin layer can improve the scratch resistance and the processability of the laminate.

The resin layer is made of, for example, any one of polyethylene terephthalate, polyethylene, polypropylene, acrylic acid, and polyimide.

The total light transmittance of the resin layer in a wavelength region of 380-780 nm is preferably 60% or more. When the total light transmittance is 60% or more, the light transmittance is more preferably 80 to 92% from the viewpoint of sufficient visibility when used in an optical filter, for example, but the total light transmittance is more preferably 80 to 92% from the viewpoint of reduction in the scorching of an image due to the haze of a resin or the like.

In addition, from the viewpoint of the image-forming mold-burnt, the resin layer is preferably an optically neutral layer which does not change the color tone. Therefore, the resin layer preferably has a constant and flat light transmittance in a wavelength region of 380 to 780 nm.

The total light transmittance can be measured using a spectrophotometer (Hitachi, manufactured by Ltd., U-3000).

< thickness >

From the viewpoint of workability and processability, the average thickness of the resin layer is preferably 12 to 500 μm, more preferably 12 to 250 μm, still more preferably 25 to 200 μm, and particularly preferably 50 to 150 μm.

The average thickness of the resin layer is an average value of thicknesses measured at any 5 points using a contact type film thickness meter (digital electronic micrometer).

[ adhesive layer ]

The adhesive layer is not particularly limited as long as the metal base material and the resin layer can be bonded thereto, and a known adhesive can be used, and for example, a two-pack curable urethane adhesive can be used.

From the viewpoint of the light transmittance of the entire laminate, the adhesive layer preferably has a total light transmittance of the same degree as that of the metal base material and the resin layer. In addition, from the viewpoint of the image-forming mold-burnt, the adhesive layer is preferably an optically neutral layer which does not change the color tone. Therefore, the resin layer preferably has a constant and flat light transmittance in a wavelength region of 380 to 780 nm.

As described above, the adhesive layer is not essential as long as the resin layer can be provided on the metal base material, and the adhesive layer may not be present.

Next, a method for manufacturing a laminate constituting the cover film will be described.

Fig. 4 to 9 are schematic cross-sectional views showing steps of the method for manufacturing a laminate including a coverlay according to the embodiment of the present invention.

First, the metal member 20 to be the metal base material 12 is prepared (see fig. 4). The metal member 20 is made of aluminum, for example. Next, the metal member 20 made of aluminum will be described as an example.

As shown in fig. 4, for example, an adhesive 21 is applied to the back surface 20b of the metal member 20.

Next, the resin layer 14 is attached to the metal member 20 with the adhesive 21 interposed therebetween. As shown in fig. 5, the adhesive 21 is cured to form the adhesive layer 15, thereby obtaining a composite material 23 of the metal member 20 and the resin layer 14. 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 coating film forming treatment is performed on the surface 20a of the metal member 20 to form an aluminum hydroxide coating film 24. The aluminum hydroxide coating 24 is formed on the surface 20a of the metal member 20 by, for example, performing electrolytic treatment using the metal member 20 as a cathode. 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, the through-hole 13 penetrating the aluminum hydroxide coating 24 and the metal member 20 in the thickness direction of the metal member 20 is formed in the aluminum hydroxide coating 24 and the metal member 20. The through-holes 13 can be formed using, for example, electrolytic dissolution treatment. 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 coating 24 is dissolved, and the aluminum hydroxide coating 24 is removed as shown in fig. 8. 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 etched so as to have a predetermined thickness and an average aperture ratio. As a result, as shown in fig. 9, the cover film 10, which is a laminate 11 of the metal base 12 and the resin layer 14 having the plurality of through-holes 13, can be obtained.

The method for producing the metal base material 12 having the plurality of through-holes 13 is not limited to the above method. For example, a plurality of through holes 13 may be formed in the metal member 20 serving as the metal base 12 by photolithography alone, thereby obtaining the metal base 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 12b of the metal base 12 via the adhesive layer 15, thereby obtaining the coverlay 10 as the laminate 11.

Next, a method for producing the laminate will be described more specifically.

[ method for producing composite ]

[ coating film formation Process ]

The coating film forming step is a step of forming an aluminum hydroxide coating film by applying a coating film forming treatment to the surface of the aluminum metal base material as described above.

< treatment for Forming coating film >

The coating film forming treatment is not particularly limited, and for example, the same treatment as the conventionally known aluminum hydroxide coating film forming treatment can be performed.

As the coating film forming process, for example, the conditions and apparatuses described in paragraphs [0013] to [0026] of japanese patent application laid-open No. 2011-201123 can be suitably employed.

The conditions for the film formation treatment vary depending on the electrolyte used, and cannot be determined in general terms, but the concentration of the electrolyte is usually 1 to 80 mass%, the liquid temperature is 5 to 70 ℃, and the current density is 0.5 to 60A/dm²The voltage is 1-100V, and the electrolysis time is 1 second-20 minutes, so as to adjust the desired coating amount.

As the electrolytic solution, it is preferable to perform electrochemical treatment using nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, or a mixed acid obtained by mixing two or more of these acids.

In the case of performing the electrochemical treatment in an electrolytic solution containing nitric acid or hydrochloric acid, a direct current may be applied between the aluminum substrate and the counter electrode, or an alternating current may be applied. When a direct current is applied to the aluminum substrate, the current density is preferably 1 to 60A/dm²More preferably 5 to 50A/dm². When the electrochemical treatment is continuously performed, it is preferable to perform the electrochemical treatment by a liquid feeding method in which electric power is supplied to the aluminum substrate through an electrolytic solution.

The amount of the aluminum hydroxide coating film formed by the coating film forming treatment is preferably 0.05 to 50g/m²More preferably 0.1 to 10g/m²。

[ through-hole formation Process ]

The through-hole forming step is a step of forming a through-hole penetrating the aluminum hydroxide coating and the metal member by performing electrolytic dissolution treatment after the coating forming step.

< electrolytic dissolution treatment >

The electrolytic dissolution treatment is not particularly limited, and an acidic solution can be used as the electrolytic solution by using a direct current or an alternating current. Among these, electrochemical treatment is preferably performed using at least one acid of nitric acid and hydrochloric acid, and more preferably electrochemical treatment is performed using a mixed acid obtained by adding at least 1 or more acid of sulfuric acid, phosphoric acid, and oxalic acid to these acids.

As the acidic solution of the electrolyte, in addition to the above-mentioned acids, the electrolyte described in each specification of 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, U.S. patent No. 4,566,959, U.S. patent No. 4,416,972, U.S. patent No. 4,374,710, U.S. patent No. 4,336,113, and U.S. patent No. 4,184,932 can be used.

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

Further, with respect to the aqueous solution mainly containing the acid, a nitric acid compound having a nitric acid ion such as aluminum nitrate, sodium nitrate, or ammonium nitrate may be added to the aqueous solution of the acid having a concentration of 1 to 100g/L in a range from 1g/L to saturation; or hydrochloric acid compounds having hydrochloric acid ions such as aluminum chloride, sodium chloride, and ammonium chloride; at least one of sulfuric acid compounds having a sulfate ion, such as aluminum sulfate, sodium sulfate, and ammonium sulfate, is used.

Here, "mainly" means that the component mainly contained in the aqueous solution is contained in an amount of 30 mass% or more, preferably 50 mass% or more, based on the whole amount of the components added to the aqueous solution. Hereinafter, other components are also the same.

In the aqueous solution mainly containing the acid, a metal contained in an aluminum alloy such as iron, copper, manganese, nickel, titanium, magnesium, or silica may be dissolved. Preferably, a liquid containing aluminum chloride, aluminum nitrate, aluminum sulfate, or the like is used so that the concentration of the acid in the aqueous solution is 0.1 to 2 mass% and the amount of aluminum ions is 1 to 100 g/L.

In the electrochemical dissolution treatment, a direct current is mainly used, but when an alternating current is used, the alternating current power source wave is not particularly limited, and a sine wave, a rectangular wave, a trapezoidal wave, a triangular wave, or the like can be used.

(nitric acid electrolysis)

Through electrochemical dissolution treatment using an electrolytic solution mainly containing nitric acid (hereinafter, also referred to as "nitric acid dissolution treatment"), through-holes having an average opening diameter of 0.1 μm or more and less than 100 μm can be easily formed.

Among them, it is preferable to use a direct current for the nitric acid dissolution treatment and to set the average current density to 5A/dm from the viewpoint of the easiness of controlling the dissolution point for forming the through-holes²Above and the electric quantity is set to be 50C/dm²Electrolytic treatment carried out under the above conditions. Further, the average current density is preferably 100A/dm²Hereinafter, the electric quantity is preferably 10000C/dm²The following.

The concentration and temperature of the electrolyte in nitric acid electrolysis are not particularly limited, and electrolysis can be performed at a temperature of 30 to 60 ℃ using a nitric acid electrolyte having a high concentration, for example, a nitric acid concentration of 15 to 35 mass%, or at a high temperature, for example, 80 ℃ or higher using a nitric acid electrolyte having a nitric acid concentration of 0.7 to 2 mass%.

The electrolysis can be performed using an electrolyte obtained by mixing at least 1 acid selected from sulfuric acid, oxalic acid, and phosphoric acid with a concentration of 0.1 to 50 mass% into the nitric acid electrolyte.

(hydrochloric acid electrolysis)

Through electrochemical dissolution treatment using an electrolytic solution mainly containing hydrochloric acid (hereinafter also referred to as "hydrochloric acid dissolution treatment"), through-holes having an average opening diameter of 1 μm or more and less than 100 μm can be easily formed.

Among them, it is preferable to use a direct current in the hydrochloric acid dissolution treatment and set the average current density to 5A/dm from the viewpoint of the easiness of controlling the dissolution point for forming the through-holes²Above and the electric quantity is set to be 50C/dm²Electrolytic treatment carried out under the above conditions. Further, the average current density is preferably 100A/dm²Hereinafter, the electric quantity is preferably 10000C/dm²The following.

The concentration and temperature of the electrolyte in hydrochloric acid electrolysis are not particularly limited, and electrolysis can be performed at a temperature of 30 to 60 ℃ using a hydrochloric acid electrolyte having a high concentration, for example, a hydrochloric acid concentration of 10 to 35% by mass, or at a high temperature, for example, 80 ℃ or higher using a hydrochloric acid electrolyte having a hydrochloric acid concentration of 0.7 to 2% by mass.

The electrolysis can be performed using an electrolyte obtained by mixing at least 1 acid selected from sulfuric acid, oxalic acid and phosphoric acid with a concentration of 0.1 to 50 mass% in the hydrochloric acid electrolyte.

[ coating film removal Process ]

The coating removal step is a step of performing chemical dissolution treatment to dissolve and remove the aluminum hydroxide coating.

The coating removal step can remove the aluminum hydroxide coating by, for example, performing an acid etching treatment or an alkali etching treatment, which will be described later.

< acid etching treatment >

The dissolution treatment is a treatment of dissolving the aluminum hydroxide film using a solution in which aluminum hydroxide is dissolved preferentially over aluminum (hereinafter, referred to as an "aluminum hydroxide solution").

Among them, the aluminum hydroxide solution is preferably an aqueous solution containing at least 1 selected from the group consisting of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, chromium compounds, zirconium compounds, titanium compounds, lithium salts, cerium salts, magnesium salts, sodium fluorosilicate, zinc fluoride, manganese compounds, molybdenum compounds, magnesium compounds, barium compounds, and halogen monomers, for example.

Specifically, examples of the chromium compound include chromium (III) oxide and chromium (VI) anhydride.

Examples of the zirconium-based compound include ammonium zirconium fluoride, and zirconium chloride.

Examples of the titanium compound include titanium oxide and titanium sulfide.

Examples of the lithium salt include lithium fluoride and lithium chloride.

Examples of the cerium salt include cerium fluoride and cerium chloride.

Examples of the magnesium salt include magnesium sulfide.

Examples of the manganese compound include sodium permanganate and calcium permanganate.

As the molybdenum compound, for example, sodium molybdate is exemplified.

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, barium selenite, barium stearate, barium sulfite, barium titanate, barium hydroxide, barium nitrate, and hydrates thereof.

Among the above barium compounds, barium oxide, barium acetate and barium carbonate are preferable, and barium oxide is particularly preferable.

Examples of the halogen monomer 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, oxalic acid, and the like, and a mixture of two or more acids may be used. Among them, nitric acid is preferably used as the acid.

The acid concentration is preferably 0.01mol/L or more, more preferably 0.05mol/L or more, and still more preferably 0.1mol/L or more. The upper limit is not particularly limited, but is usually preferably 10mol/L or less, and more preferably 5mol/L or less.

The dissolution treatment is performed by bringing the aluminum base material on which the aluminum hydroxide film is formed into contact with the above-mentioned dissolution liquid. The method of contacting is not particularly limited, and examples thereof include a dipping method and a spraying method. Among them, the spraying method is preferable.

The spraying method is an advantageous method when the through-holes are formed continuously, and the time for ejecting the liquid can be determined by the processing length and the conveying speed. The spray coating method can supply a fresh liquid to the reaction interface, and thus can efficiently perform the treatment. The time of the spray treatment is preferably 1 second or more and 30 minutes or less, and more preferably 2 seconds or more and 20 minutes or less.

< etching treatment >

The etching treatment is, for example, an alkali etching treatment in which the surface layer is dissolved by bringing the aluminum hydroxide coating film into contact with an alkali solution.

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 potash. Examples of the alkali metal salt 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; alkali metal aluminates such as sodium aluminate and potassium aluminate; alkali metal aldonates 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 a caustic alkali and an alkali metal aluminate are preferable in terms of a high etching rate and low cost. In particular, an aqueous solution of sodium hydroxide is preferred.

The concentration of the alkali solution is preferably 0.1 to 50 mass%, more preferably 0.2 to 10 mass%. When aluminum ions are dissolved in the alkali solution, the concentration of aluminum ions is preferably 0.01 to 10 mass%, more preferably 0.1 to 3 mass%. The temperature of the alkali solution is preferably 10-90 ℃. The treatment time is preferably 1 to 120 seconds.

Examples of the method of bringing the aluminum hydroxide film into contact with the alkaline solution include a method of passing the aluminum base material on which the aluminum hydroxide film is formed through a tank to which the alkaline solution is added, a method of immersing the aluminum base material on which the aluminum hydroxide film is formed in a tank to which the alkaline solution is added, and a method of spraying an alkaline solution onto the surface of the aluminum base material on which the aluminum hydroxide film is formed (aluminum hydroxide film).

[ resin layer Forming Process ]

The resin layer forming step is a step of providing a resin layer on a metal member having no through-hole.

The method for forming the resin layer is not particularly limited, but examples thereof include a dry lamination method, a wet lamination method, an extrusion lamination method, and an inflation lamination method.

As the dry lamination method, for example, the conditions and apparatus described in paragraphs [0067] to [0078] of Japanese patent application laid-open Nos. 2013-121673 can be suitably employed.

[ cover film ]

The laminate formed by the above method can be used as a cover film. When the cover film is attached to the optical monitor, the cover film can be assembled by using a transparent double-sided adhesive as an adhesive layer or a process of assembling the optical monitor.

In addition to the above, for example, optically transparent resins (OCR, Optical Clear Resin) such as optically Clear Adhesive (OCA, Optical Clear Adhesive) and UV (ultraviolet) curable resins can be used for attaching the cover film to the Optical monitor. As a commercially available product, for example, a color drawing film (Graphic film) IJ8150 (product number) manufactured by Sumitomo 3M Limited can be used.

When the outermost surface of the cover film is made of metal, a commercially available protective film may be attached to prevent scratches on the metal surface. As a commercially available protective film, for example, a coating film (OverlaminaLe film) IJ4176 (product number) manufactured by Sumitomo 3M Limited can be used.

An optical monitor is a display device having an image display surface for displaying images such as characters and pictures and moving images by transmitting or reflecting light, and for example, a liquid crystal display device or an organic el (organic electro luminescence) display device, or a projection unit of a head-up display and a beam splitter surface for an air display using these display devices are also included in the optical monitor.

[ image display apparatus ]

The image display device is a device in which the cover film is provided on the image display surface.

By incorporating the cover film on the image display surface, the visibility of the image display is not reduced, and the design of the screen when the image display device is not used, that is, the design of the screen when the power supply is turned off, can be improved.

The present invention is basically constituted as described above. Although the cover film and the image display device of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various improvements and modifications can be made without departing from the scope of the present invention.

Examples

The features of the present invention will be described in more detail with reference to examples. The materials, reagents, amounts of use, amounts of substances, ratios, processing contents, processing procedures and the like shown in the following examples can be appropriately modified without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited to the specific examples shown below.

In this example, the laminates of examples 1 to 5 and comparative examples 1 to 4 were produced as coverlays, and the laminates of examples 1 to 5 and comparative examples 1 to 4 were evaluated for visibility of images, design of screens when no image was displayed, and scratch resistance. In comparative example 5, which was used as a standard for evaluation, the visibility of an image, the design of a screen when no image was displayed, and the scratch resistance were also evaluated.

The results are shown in table 3 below. In addition, the visibility of an image and the design of a screen when no image is displayed will be described below.

< evaluation of visibility of image >

The cover films corresponding to the examples were used in 5 kinds (examples 1 to 5) and the cover films corresponding to the comparative examples in 4 kinds (comparative examples 1 to 4), and the cover films were attached to an image display device, and compared with the case where the cover films were not used by sensory evaluation of 10 subjects. The image display device used a liquid crystal display 24 inches made by Dell inc. For the evaluation, the illuminance of the display was evaluated on 3 levels of standard 10% increase in illuminance and 20% increase in illuminance. The evaluation of the visibility of the image was performed based on the evaluation criteria shown below.

Table 2 shows the structures of examples 1 to 5 and comparative examples 1 to 5. In table 2, "-" indicates none.

Evaluation criterion for evaluating visibility of image

Image visibility to display luminance standard without cover film (comparative example 5)

4: 5-10 persons evaluated as being uninvolved

3: 3-4 persons evaluated as being uninvolved

2: people evaluated as non-conscious 1-2 people

1: person 0 evaluated as being unincernible

< feeling when turning off display Power >

The cover films 5 (examples 1 to 5) corresponding to the examples and 4 (comparative examples 1 to 4) corresponding to the comparative examples shown in table 2 were attached to the image display device, respectively, and the texture when the display power was turned off was compared with the texture when the cover films were not used. The screen was black when the cover film was not used, but sensory evaluation was made by 10 subjects as to whether the texture was improved when the cover film was attached, in the same manner as in the visibility evaluation of the image.

The evaluation items were texture and surface uniformity. The evaluation of the texture when the display was turned off was evaluated by the evaluation criteria shown below. Table 3 shows the results of evaluation regarding the visibility of the image and the texture when the display was powered off.

In addition, regarding the color of "feature of appearance" in table 3, sensory evaluation was performed by 10 subjects in the same manner as the visibility evaluation of the image.

Evaluation criterion for evaluation of texture when power supply to display is turned off

4: the evaluation is better for 5-10 people

3: 3-4 persons evaluated as better

2: the evaluation is better people 1-2

1: person evaluated as better

[ Table 2]

	Covering film	Opening ratio	Light transmittance	Aggregate through-penetration rate
					Example 1	Metal through foil (5 μm) + PET resin (125 μm)	95％	95％	80％
Example 2	Metal through foil (5 μm) + PET resin (125 μm)	80％	80％	50％
					Example 3	Metal through foil (5 μm) + PET resin (125 μm)	75％	75％	30％
Example 4	Metal through foil (5 μm) + PET resin (125 μm)	70％	70％	15％
					Example 5	Metal through foil (5 μm) + PET resin (125 μm)	53％	55％	6％
Comparative example 1	Metal through foil (5 μm) + PET resin (125 μm)	48％	50％	4％
					Comparative example 2	Metal through foil (5 μm) + PET resin (125 μm)	30％	30％	2％
Comparative example 3	Aluminum was deposited on PET resin (125 μm) by vapor deposition	-	30％	-
					Comparative example 4	Mechanical narrow-hole foil 20 μm	50％	50％	0％
Comparative example 5	Is free of	-	100％	-

Examples 1 to 5 and comparative examples 1 to 5 will be described below.

(example 1)

The laminate of example 1 will be explained.

< preparation of laminate >

As a metal base material, a 100mm square aluminum foil (manufactured by UACJ Corporation, alloy No. 1N30, thickness 9 μm) was prepared. Then, two-pack curable urethane adhesives (manufactured by SANYU rec. ltd., SU3600A, and SU3600B) were weighed so that the mass ratio thereof was 30: 100, and these were dissolved in ethyl acetate to prepare an adhesive layer coating liquid having a solid content concentration of 30 mass%.

An adhesive layer coating liquid was applied to the aluminum foil, and a 100mm square PET film (TOYOBO co., ltd., COSMOSHINE (registered trademark) a4100 (single-sided easy adhesive layer) having a thickness of 125 μm) constituting a resin layer was laminated thereon. The drying temperature was set to 70 ℃ and the drying time was set to 1 minute to cure the aluminum foil, thereby producing a composite material of an aluminum foil and a resin layer. The thickness of the adhesive at this time was 3 μm.

(perforation treatment)

Aluminum hydroxide coating film formation treatment (coating film formation step)

An electrolytic treatment was performed using an electrolytic solution (nitric acid concentration 1%, sulfuric acid concentration 0.2%, aluminum concentration 0.5%) maintained at 50 ℃ and using the aluminum foil as a cathode, thereby forming an aluminum hydroxide film on the aluminum foil. In addition, electrolytic treatment was performed by a direct current power supply. The DC current density was set to 33A/dm²Setting the electric quantity to 400C/dm²。

After the formation of the aluminum hydroxide film, the film was washed with water by spraying.

As a result of observing and measuring a cross section cut by Focused Ion Beam (FIB) cutting with a Scanning Electron Microscope (SEM), the thickness of the aluminum hydroxide film was 1 μm.

Electrolytic dissolution treatment (through-hole formation step)

Next, an electrolyte (nitric acid concentration 1%, sulfuric acid concentration 0.2%, aluminum concentration 0.5%) kept at 50 ℃ was used, and an aluminum foil was used as an anode, and the current density was 40A/dm²The total electric quantity is 400C/dm²Electrolytic treatment was performed under the conditions of (1) to form a through-hole penetrating the aluminum foil and the aluminum hydroxide film. In addition, electrolytic treatment was performed by a direct current power supply.

After the through-holes were formed, water washing was performed by spraying, and the aluminum foil was dried.

Removal treatment of aluminum hydroxide coating (coating removal step)

Next, the aluminum foil after the electrolytic dissolution treatment was immersed in an aqueous solution (liquid temperature 35 ℃) having a sodium hydroxide concentration of 5 mass% and an aluminum ion concentration of 0.5 mass% for 30 seconds, and then immersed in an aqueous solution (liquid temperature 50 ℃) having a sulfuric acid concentration of 30% and an aluminum ion concentration of 0.5 mass% for 20 seconds, thereby dissolving and removing the aluminum hydroxide film. Thereafter, the aluminum foil was washed with water by spraying and dried, thereby obtaining an aluminum foil having through-holes.

(alkaline etching Process)

An etching treatment was performed at 50 ℃ using an aqueous solution having a sodium hydroxide concentration of 5 mass% and an aluminum ion concentration of 1 mass% so that the composite of the aluminum foil and the resin layer had a predetermined thickness and an average aperture ratio, and the immersion time was 500 seconds. In this way, a laminate of an aluminum foil having through-holes and a resin layer was obtained.

(example 2)

Example 2 was the same as example 1 except that the composite of the aluminum foil and the resin layer was immersed in the alkali etching treatment for 400 seconds as compared with example 1.

(example 3)

Example 3 was the same as example 1 except that the composite of the aluminum foil and the resin layer was immersed in the alkali etching treatment for 370 seconds as compared with example 1.

(example 4)

Example 4 was the same as example 1 except that the composite of the aluminum foil and the resin layer was immersed in the alkali etching treatment for 330 seconds as compared with example 1.

(example 5)

Example 5 was the same as example 1 except that the composite of the aluminum foil and the resin layer was immersed in the alkali etching treatment for 200 seconds as compared with example 1.

Comparative example 1

Comparative example 1 was the same as example 1 except that the immersion time of the composite of the aluminum foil and the resin layer in the alkali etching treatment was 150 seconds as compared with example 1.

Comparative example 2

Comparative example 2 was the same as example 1 except that the composite of the aluminum foil and the resin layer was immersed in the alkali etching treatment for 100 seconds as compared with example 1.

Comparative example 3

In comparative example 3, aluminum was deposited on one surface of a 125 μm thick PET film (TOYOBO co., ltd., COSMOSHINE (registered trademark) a4100 (single-sided easy adhesive layer)) so that the light transmittance was 30%.

Comparative example 4

As comparative example 4, a commercially available mechanical narrow-hole foil (opening diameter 300. mu.m, opening ratio 50%, thickness 20 μm) was used as it is.

Comparative example 5

Comparative example 5 is an example in which no cover film was used. Therefore, the process of manufacturing the laminate does not exist. As described above, comparative example 5 was used as a standard for evaluation.

[ Table 3]

As shown in table 3, in examples 1 to 5, the number of subjects evaluated to have good texture was large compared to comparative example 5, i.e., no cover film was present. It is also known that the visibility of the display is reduced in the examples 1 and 2 to 4, in which the difference from the case without the cover film (comparative example 5) is recognized, and the number of subjects is reduced by increasing the illuminance of the display.

On the other hand, it is known that the laminate in comparative examples 1 and 2 has a structure close to that of the example, but even if the luminance of the display is increased, the visibility is hardly improved. The texture evaluation obtained in comparative examples 1 and 2 was slightly inferior to that obtained in examples, but the reason for this was that the number of through-holes was small and fine color patterns in examples were hardly visible.

In comparative example 3, a silver appearance having a glossy feel like a half mirror was exhibited by aluminum deposition, but the evaluation of the feel was not high because it was an appearance of a plated plate like a mirror. Since there was no fine color pattern, slight deformation was observed when the cover film was stuck, and there were few subjects evaluated to have good surface uniformity.

In comparative example 4, since the regularly arranged through-holes themselves were observed, the video visibility was not related to the illuminance of the display and no subject evaluated as being unobtrusive. Regarding the texture, the evaluation of the texture was not high although the uniformity was not poor.

Fig. 12 is a view showing a cover film on which a plurality of through holes are formed, and is a light transmission image by an optical microscope.

Description of the symbols

10-cover film, 11-laminate, 12-metal substrate, 12a, 17a, 20 a-surface, 12b, 20 b-back surface, 13-through hole, 13 g-through hole, 14-resin layer, 15-adhesive layer, 17-optical monitor, 20-metal part, 21-adhesive, 23-composite, 24-aluminum hydroxide coating, T-thickness.

Claims

1. A cover film comprising a laminate, the laminate comprising: a metal base material provided 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, in the cover film,

the average opening ratio of the plurality of through-holes is set to G%, the average opening ratio is set to 50% < G% < 95%,

at least one of the arrangement positions and the shapes of the through holes is random, and at least 5% of all the through holes are communicated with the adjacent through holes.

2. The mulch film according to claim 1 wherein,

when the thickness of the metal base material is T [ mu ] m, the ratio Q represented by the average aperture ratio G%/the thickness T [ mu ] m is 1 to 50.

3. The mulch film according to claim 1 or 2 wherein,

the resin layers are disposed on respective surfaces of the metal base material.

4. The mulch film according to any one of claims 1 to 3 wherein,

the total light transmittance of the resin layer in a wavelength region of 380 nm-780 nm is more than 60%.

5. The mulch film according to any one of claims 1 to 4 wherein,

the resin layer is made of any one of polyethylene terephthalate, polyethylene, polypropylene, acrylic acid, and polyimide.

6. The mulch film according to any one of claims 1 to 5 wherein,

the average thickness of the resin layer is 12-500 μm.

7. The mulch film according to any one of claims 1 to 6 wherein,

the average thickness of the metal base material is 10 [ mu ] m or less.

8. The mulch film according to any one of claims 1 to 7 wherein,

the metal substrate is comprised of a metal selected from the group consisting of aluminum, copper, silver, gold, platinum, stainless steel, titanium, tantalum, molybdenum, niobium, zirconium, tungsten, beryllium copper, phosphor bronze, brass, nickel silver, tin, zinc, iron, nickel, permalloy, nichrome, 42 alloy, kovar, monel, inconel, and hastelloy.

9. An image display device comprising the cover film according to any one of claims 1 to 8 provided on an image display surface.