JP2024018661A - Reflective film, wound body, and display device for electronic device - Google Patents

Abstract

To provide a reflective film which comprises a first reflective layer and a second reflective layer that are laminated together and offers improved reflectance and brightness.SOLUTION: A reflective film is provided, comprising a first reflective layer, adhesive space layer, and second reflective layer arranged in the described order, the adhesive space layer comprising a space portion and adhesive portions made of an adhesive composition and scattered in a surface direction.SELECTED DRAWING: Figure 1

Description

The present invention relates to reflective films. Specifically, the present invention relates to a reflective film that can be suitably used as a component of a display device for electronic devices such as a liquid crystal display.

Reflective films are used in many fields, including liquid crystal displays, lighting equipment, and illuminated signboards. In recent years, in the field of display devices for electronic devices such as liquid crystal displays, improvements in display performance and power saving of backlights have been studied, and the performance of backlight units has been improved by supplying as much light as possible to liquid crystals. Reflective films are also required to have even better light reflectivity (also simply referred to as "reflectivity").

As a reflective film with high light reflectivity, for example, a reflective polarizer in which two types of transparent polyester layers having different refractive indexes are laminated with adjusted thicknesses has been proposed (Patent Document 1).
Furthermore, a white film made porous by dispersing a fine powder filler such as titanium oxide in a resin matrix such as polyester or polyolefin and stretching the film has also been proposed (Patent Documents 2 to 4).
In addition, metal thin film specular reflective films have been proposed in which a metal thin film with high reflectance such as silver or aluminum is formed on a base material such as a plastic sheet or metal plate by vapor deposition or sputtering (Patent Documents 5 and 6). .
Furthermore, reflective films made by combining the above-mentioned white film and the above-mentioned specular reflection film have also been proposed (Patent Documents 7 to 9).

Japanese Patent Application Publication No. 2014-178697 Japanese Patent Application Publication No. 04-239540 Japanese Patent Application Publication No. 2005-031653 Japanese Patent Application Publication No. 2012-035616 Japanese Patent Application Publication No. 10-128908 Japanese Patent Application Publication No. 2006-126236 Japanese Unexamined Patent Publication No. 10-193494 International Publication No. 2005/039872 International Publication No. 2016/072472

In recent years, in the field of display devices for electronic devices such as liquid crystal displays, devices have become larger and display performance has become more sophisticated, and there is a need to supply as much light as possible to liquid crystal panels. Therefore, in order to save power and increase the amount of light supplied from the backlight as much as possible, there is a need for a reflective film that has high reflectance and can provide high brightness. Furthermore, it is required to improve the brightness of the reflective film in order to suppress the difference in brightness between areas where there is a light source and areas where there is no light source, thereby suppressing so-called brightness unevenness.

As mentioned above, Patent Documents 5 and 6 disclose a metal thin film specular reflection film in which a metal layer of silver, aluminum, etc. is formed by vapor deposition, sputtering, etc. on the back side of a base material layer made of a resin film, that is, the side opposite to the viewing side. A film is disclosed. Although such a metal thin film specular reflection film can be expected to have high reflective properties, it has been necessary to further increase the brightness.
Further, in Patent Documents 7 to 9, it was necessary to improve handling properties by preventing peeling between the white film (base layer) and the metal layer during the process of manufacturing the reflective film.
Incidentally, Patent Document 9 describes a method of forming a metal layer on the back side of a base material layer, in which a smooth coat layer is provided on the surface of the base material layer and then a metal is vapor-deposited. A method of laminating a material layer and a metal layer via an adhesive layer or an adhesive layer, and a method of laminating a base material layer and a metal layer by simply stacking the base material layer and the metal layer with an air layer interposed between the base material layer and the metal layer. Methods are disclosed.

An object of the present invention is to provide a new reflective film that can further improve the reflectance and brightness and prevent peeling between the reflective layers during the manufacturing process. There is a particular thing.

The present inventors have conducted various studies on bonding methods between reflective layers, and have found that the above problem can be solved by interspersing adhesive portions between reflective layers.
That is, the gist of the present invention is as follows.

[1] The first aspect of the present invention includes a first reflective layer, an adhesive space layer, and a second reflective layer in this order, and the adhesive space layer has an adhesive formed of a space and an adhesive composition. The reflective film has a structure in which the plurality of adhesive parts are scattered in the surface direction.

[2] A second aspect of the present invention is the reflective film according to the first aspect, wherein the area ratio of the adhesive portion is 1 to 50%.
[3] A third aspect of the present invention is the reflective film according to the first or second aspect, wherein the adhesive portion has a unit area of 0.01 to 0.5 mm ² .
[4] A fourth aspect of the present invention is the reflective film according to any one of the first to third aspects, wherein the adhesive portion has an average thickness of 1 to 20 μm.

[5] A fifth aspect of the present invention is the reflective film according to any one of the first to fourth aspects, wherein the first reflective layer has a light reflectance of 95% or more at a wavelength of 550 nm.
[6] A sixth aspect of the present invention is the reflective film according to any one of the first to fifth aspects, wherein the first reflective layer has a light transmittance of 1.0% or more at a wavelength of 550 nm. be.
[7] A seventh aspect of the present invention is a reflective film according to any one of the first to sixth aspects, wherein the first reflective layer contains a polyolefin resin or a polyester resin as a main component resin. .

[8] An eighth aspect of the present invention is the reflective film according to any one of the first to seventh aspects, wherein the second reflective layer has a light reflectance of 50% or more at a wavelength of 550 nm.
[9] A ninth aspect of the present invention is the reflective film according to any one of the first to eighth aspects, wherein the second reflective layer has a light transmittance of 1.0% or less at a wavelength of 550 nm. be.
[10] A tenth aspect of the present invention is a reflective film in which, in any one of the first to ninth aspects, the second reflective layer is mainly made of metal.

[11] An eleventh aspect of the present invention is the reflective film according to any one of the first to tenth aspects, comprising a protective layer on at least one surface of the second reflective layer.

[12] A twelfth aspect of the present invention is a wound body formed by winding the reflective film of any one of the first to eleventh aspects around a core.

[13] A thirteenth aspect of the present invention is a display device for an electronic device, comprising the reflective film according to any one of the first to eleventh aspects.

According to the reflective film proposed by the present invention, it is possible to further improve not only the reflectance but also the brightness, and to provide a new reflective film with excellent handling properties that can prevent peeling between reflective layers during the manufacturing process. I can do it. Such a reflective film is particularly suitable, for example, as a component of a display device for an electronic device.

1 is a diagram schematically showing a cross section of a reflective film according to an example of the present invention. FIG. 7 is a diagram schematically showing a cross section of a reflective film according to another example of the present invention. FIG. 7 is a diagram schematically showing a cross section of a reflective film according to still another example of the present invention. FIG. 4 is a plan view schematically showing an example of the top surface of the reflective film shown in FIGS. 1, 2, and 3 when the first reflective layer 1 is peeled off.

Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

<<Reflective film>>
A reflective film according to an example of an embodiment of the present invention (referred to as "reflective film of the present invention") is a reflective film comprising a first reflective layer 1, an adhesive space layer 2, and a second reflective layer 3 in this order. .

The reflective film of the present invention includes a first reflective layer 1 (also simply referred to as "reflective layer 1"), an adhesive space layer 2, and a second reflective layer 3 (also simply referred to as "reflective layer 3") in this order. For example, it is possible to include other layers and other elements. For example, as described later, a protective layer 4, a support layer 5, an anchor coat layer 6, etc. can be provided as appropriate. It is not limited to these.

Note that the "first reflective layer 1" in the present invention may be any layer having light reflectivity, and more preferably has a light reflectance of 95% or more at a wavelength of 550 nm.
On the other hand, the "second reflective layer 3" in the present invention may be any layer having light reflectivity, and preferably has a light reflectance of 50% or more at a wavelength of 550 nm.
In the present invention, the "reflective film" may be any film that has light reflective performance, and more preferably has a light reflectance of 95% or more at a wavelength of 550 nm.

<Adhesive space layer>
As shown in FIGS. 1 to 4, the adhesive space layer 2 included in the reflective film of the present invention has a space 2A and an adhesive part 2B made of an adhesive composition, and the plurality of adhesive parts 2B are arranged on a surface. It has a configuration in which it is scattered in the direction. In other words, the adhesive space layer 2 is composed of the space part 2A and a plurality of adhesive parts 2B, and has a configuration in which the plurality of adhesive parts 2B are scattered within the space part 2A. Therefore, when the adhesion space layer 2 is viewed from above, the plurality of adhesion parts 2B are arranged in a dotted manner in the planar direction.

The present inventors have confirmed that when a member provided with the reflective layer 1 and a member provided with the reflective layer 3 are bonded together over the entire surface, the reflectivity of the entire reflective film decreases. Therefore, we considered providing an adhesive part only on a part of the bonding surfaces of both. At that time, we considered, for example, linear, lattice, and dotted patterns as the arrangement patterns of the adhesive portions. As a result, it was found that when the adhesive part is provided in a linear shape, the releasability differs depending on the direction, and it becomes easy to peel off when force is applied in a direction where the releasability is weak, so that it is insufficient in terms of handling properties. Further, when the adhesive portions are provided in a grid pattern, the marks of the adhesive portions become noticeable when viewed through the reflective film, resulting in a problem in that the appearance is not good. On the other hand, by arranging the adhesive parts in dots in the plane direction, not only can the reflectance and brightness be increased, but also the anisotropy of peelability can be eliminated, and the traces of the adhesive parts are also less noticeable. I found out that it can be eliminated.

In the reflective film of the present invention, the adhesive space layer 2 may be present between the reflective layer 1 and the reflective layer 3. That is, the adhesive space layer 2 in the reflective film of the present invention may be directly laminated with the reflective layer 1 or the reflective layer 3, or another layer or other member may be present between the reflective layer 1 or the reflective layer 3. You may do so.

The existing area ratio of the bonded portion 2B, that is, the ratio of the total area of the bonded portion 2B existing within the surface of the bonded space layer 2 when the bonded space layer 2 is viewed from above is preferably 1 to 50%.
If the existing area ratio of the adhesive portion 2B is 1% or more, the member provided with the reflective layer 1 or the member provided with the reflective layer 3 will be difficult to peel off during the manufacturing process, so that handling properties can be improved. . Furthermore, if the area ratio of the adhesive portion 2B is 50% or less, reduction in brightness can be suppressed.
From this point of view, the area ratio of the adhesive portion 2B is preferably 1% or more, particularly 2% or more, and even more preferably 3% or more. On the other hand, it is preferably 50% or less, especially 49% or less, and even more preferably 48% or less.
Further, by adjusting the peel strength between the reflective layer 1 side and the reflective layer 3 side, the reflective layer 1 and the reflective layer 3 can be treated separately, and recyclability can be imparted. From the viewpoint of imparting recyclability and further suppressing a decrease in brightness, the area ratio of the adhesive portion 2B is preferably 45% or less, more preferably 40% or less, even more preferably 35% or less, and even more preferably 30% or less. It is preferably 25% or less, even more preferably 20% or less.

The existing area ratio of the adhesive part 2B is determined by calculating the total area of the adhesive part 2B by viewing the adhesive space layer 2 in plan, and based on the area of the adhesive space layer 2, the existing area ratio of the adhesive part 2B = (adhesion area ratio). It can be determined from (total area of portion 2B/area of adhesive space layer 2) x 100.
At this time, the area of the adhesive space layer 2 is the total area of the adhesive space layer 2 in plan view. If it is difficult to measure the area of the adhesive space layer 2, assuming that the area of the adjacent layer in contact with the adhesive space layer 2 is the area of the adhesive space layer 2, (total area of adhesive part 2B/area of adjacent layer) )×100. In the embodiment, the first reflective layer is peeled off to expose the adhesive portion of the adhesive space layer, and the area of the surface where the adhesive portion is exposed corresponds to the area of this adjacent layer.
If the areas of the layers adjacent to the adhesive space layer 2 are different on the upper and lower surfaces of the adhesive space layer 2, the layer with the smaller area may be assumed to be the area of the adhesive space layer 2 and calculated as above. .
Further, the total area of the adhesive part 2B can be determined by viewing the adhesive space layer 2 in plan and using image analysis software using a laser microscope, an electron microscope, etc.; It can also be determined from the unit area of the portion 2B x the total number of bonded portions 2B.
In addition, if the adhesive parts 2B have the same size and are arranged at equal intervals over the entire surface of the adhesive space layer 2, the total area and existing area ratio of the adhesive parts 2B in a unit area (for example, 10 mm x 10 mm square) are It may be calculated.

The shape of each adhesive part 2B in the adhesive space layer 2 is arbitrary. It may be a circle, an ellipse, a triangle, a quadrilateral, a pentagon, a larger polygon, or other shapes.

When the unit area of the adhesive part 2B, that is, the adhesive space layer 2 is viewed from above, the area of one adhesive part 2B is preferably 0.01 to 0.5 mm ² .
If the area of each adhesive part 2B is 0.01 mm2 or ^more , the member provided with the reflective layer 1 or the member provided with the reflective layer 3 will be difficult to peel off during the manufacturing process, etc., thereby improving handling properties. I can do it. In addition, if the area of each adhesive part 2B is 0.5 ^mm2 or less, it is possible to suppress a decrease in brightness, and when it is made into a reflective film, the part where the adhesive part 2B is provided will be noticeable and the appearance will be poor. You can prevent it from happening.
From this viewpoint, the unit area of the adhesive portion 2B is preferably 0.01 mm ² or more, particularly 0.02 mm ² or more, and even more preferably 0.03 mm ² or more. On the other hand, it is preferably 0.2 mm ² or less, and even more preferably 0.19 mm ² or less.
Further, from the viewpoint of imparting recyclability and further suppressing a decrease in brightness, the unit area of the adhesive portion 2B is preferably 0.15 mm ² or less, more preferably 0.13 mm ² or less, and 0. More preferably, it is .10 mm ² or less.

In addition, the unit area of the adhesive part 2B is determined by observing the adhesive space layer 2 in a plan view with a laser microscope, an electron microscope, etc., measuring the area of a plurality of adhesive parts 2B by image analysis, and calculating the average value. It can be calculated and found. If the adhesive parts 2B have the same size and are arranged at equal intervals over the entire surface of the adhesive space layer 2, the average value of the area of the plurality of adhesive parts 2B existing in a unit area (for example, 10 mm x 10 mm square) is It may be calculated.
Furthermore, the average area (mm ² ) of the bonded portion 2B can also be determined using image analysis software.

When the adhesion space layer 2 is viewed in plan, the arrangement of the adhesion parts 2B is arbitrary as long as a plurality of adhesion parts 2B are arranged in a dispersed manner. For example, the array may be arranged in rows in the horizontal direction, in rows in the vertical direction, in rows in the diagonal direction, arranged at equal distances in the vertical, horizontal and diagonal directions, or any other arrangement.
Further, from the viewpoint of adjusting adhesiveness, a configuration may be adopted in which adhesive portions 2B of different shapes and/or unit areas are combined and arranged. In addition, from the viewpoint of reflectance and brightness and adhesion between reflective layers, it is necessary to increase the area ratio and/or unit area of the adhesive part 2B around the reflective film, and increase the existence area ratio and/or unit area of the adhesive part 2B in the central part of the reflective film. A configuration in which the area ratio and/or unit area is reduced is also preferable.

The average thickness of the adhesive portion 2B, ie, the average thickness of the adhesive space layer 2 when viewed in cross section, is preferably 1 to 20 μm.
If the average thickness of the adhesive part 2B is 1 μm or more, the member provided with the first reflective layer 1 or the member provided with the second reflective layer 3 will be difficult to peel off during the manufacturing process, so handling properties will be improved. can be improved. On the other hand, it is preferable that the average thickness of the adhesive portion 2B is 20 μm or less, since it will not collapse when pressure is applied and a neat dot-like arrangement can be maintained.
From this viewpoint, the average thickness of the bonded portion 2B is preferably 1 μm or more, particularly 2 μm or more, 3 μm or more, and even more preferably 4 μm or more. On the other hand, it is preferably 10 μm or less, especially 9 μm or less, especially 8 μm or less, and even more preferably 7.5 μm or less.

The average thickness of the adhesive portions 2B is determined by cutting the reflective film in the thickness direction, measuring the thickness of the multiple adhesive portions 2B in the cross section by image analysis using a laser microscope, an electron microscope, etc. It can be determined by calculating the average value.

Further, the average thickness of the adhesive portion 2B is preferably 1 to 20% of the total thickness of the reflective film.
If the average thickness of the adhesive part 2B is 1% or more with respect to the thickness of the entire reflective film, the adhesive part 2B has an appropriate thickness, so the member is equipped with the reflective layer 1 or the reflective layer 3. Since the attached members are less likely to peel off during the manufacturing process, handling properties can be improved. On the other hand, if it is 20% or less, the bonded portion 2B is not too thick, so it does not collapse when pressure is applied, and a beautiful dot arrangement can be maintained, which is preferable.
From this point of view, it is preferable that the average thickness of the adhesive part 2B is 1% or more of the total thickness of the reflective film, especially 1.2% or more, especially 1.5% or more, especially 2% or more. Among them, it is even more preferable that the content is 3% or more. On the other hand, it is preferably 20% or less, especially 10% or less, and even more preferably 9% or less.

The adhesive part 2B in the adhesive space layer 2 preferably has a total light transmittance of 80% or more, especially 85% or more, and especially 90%, from the viewpoint of not impairing the reflectance and brightness of the reflective film of the present invention. % or more is more preferable.
Note that the total light transmittance of the adhesive portion 2B can be measured according to JIS K7361-1.

The adhesive portion 2B in the adhesive space layer 2 is made of, for example, urethane resin, acrylic resin, rubber resin, silicone resin, polyester resin, polyamide resin, epoxy resin, polyvinyl acetate resin, or vinyl alkyl ether. It can be formed by curing an adhesive resin composition whose main component is resin, fluorine resin, or the like.
When the adhesive resin composition is cured, it is preferably transparent and has a total light transmittance of 80% or more as described above.
At this time, the adhesive resin composition may be cured by any of thermal curing, photocuring, and drying.

Here, in the present invention, the "main component resin" means an oligomer or polymer having the largest mass proportion among the oligomers or polymers constituting each composition, each layer, or each member (for example, a film), and the main component resin It is permissible to contain other resins as long as they do not interfere with the functions of the resin. In this case, the content ratio of the main component resin is such that it accounts for 50% by mass or more, preferably 70% by mass or more, particularly preferably 90% by mass or more (including 100% by mass) of the oligomers or polymers constituting each layer. be.
Furthermore, in the present invention, the term "adhesive part" includes an adhesive part, and the term "adhesive" includes an adhesive.

In order to arrange the plurality of adhesive parts 2B so as to be scattered in the surface direction, for example, the adhesive composition can be applied (printed) using a gravure plate, applied (printed) in a predetermined pattern using an inkjet, or applied in a predetermined pattern. By applying (printing) a predetermined pattern through holes in the pattern, the plurality of adhesive parts 2B can be arranged so as to be scattered in the surface direction, in other words, they can be arranged in a dot shape. However, the method is not limited to these methods.

<First reflective layer>
The first reflective layer 1 in the reflective film of the present invention is preferably a layer containing a thermoplastic resin and a filler, and preferably contains a thermoplastic resin as a main component resin.
The thermoplastic resin is not particularly limited as long as it can maintain reflectivity and excellent durability. Preferred examples include various thermoplastic resins such as polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acrylic resins, polyimide resins, fluorine resins, olefin resins such as polyethylene and polypropylene, and cycloolefin resins. I can do it. Note that the thermoplastic resins may be used alone or in a mixture of two or more types.

Among the above, when emphasis is placed on reflection characteristics, production cost, hydrolysis resistance, etc., it is preferable to select a polyolefin resin as the main component resin of the reflective layer 1.
Examples of the polyolefin resin include polypropylene resins such as polypropylene and propylene-ethylene copolymers, polyethylene resins such as polyethylene, high-density polyethylene, and low-density polyethylene, and cycloolefin resins such as ethylene-cyclic olefin copolymers. Examples include at least one polyolefin resin selected from olefin elastomers such as ethylene-propylene rubber (EPR) and ethylene-propylene-diene terpolymer (EPDM). Among these, polypropylene resins (PP), polyethylene resins (PE), and cycloolefin resins are preferred from the viewpoint of mechanical properties and flexibility, and among these, particularly, they have excellent heat resistance and mechanical properties such as elastic modulus. Polypropylene resins (PP) and cycloolefin resins (COC, COP) are preferred from the viewpoint of high performance.

On the other hand, if the rigidity and heat resistance of the film are important, it is preferable to select a polyester resin as the main component resin of the reflective layer 1.
As the polyester resin, aromatic polyester is preferably selected when heat resistance, hydrolysis resistance, etc. are important, and among them, polyethylene terephthalate, polyethylene-2,6-naphthalene dicarboxylate, polypropylene terephthalate, At least one type of polyester resin selected from polybutylene terephthalate and the like can be mentioned.

The filler contained in the reflective layer 1 is not particularly limited in type, and may include inorganic fine powder, organic fine powder, and the like.
Examples of the inorganic fine powder include calcium carbonate, magnesium carbonate, barium carbonate, magnesium sulfate, barium sulfate, calcium sulfate, zinc oxide, magnesium oxide, calcium oxide, titanium oxide, zinc oxide, alumina, aluminum hydroxide, hydroxyapatite, Examples include silica, mica, talc, kaolin, clay, glass powder, asbestos powder, zeolite, silicate clay, and the like. These can be used alone or in combination of two or more. Among these, in consideration of the refractive index difference with the thermoplastic resin constituting the reflective film of the present invention, those with a large refractive index are preferred, and calcium carbonate, barium sulfate, titanium oxide, or those with a refractive index of 1.6 or more are preferable. Particular preference is given to using zinc oxide.

The reflective layer 1 may contain other components in addition to the thermoplastic resin and filler.
Examples of the above "other ingredients" include antioxidants, light stabilizers, heat stabilizers, dispersants, ultraviolet absorbers, optical brighteners, compatibilizers, lubricants, and fillers other than fine powder fillers. be able to.

Further, recycled raw materials generated in the manufacturing process of the reflective film of the present invention may be added to the reflective layer 1 within a range that does not impair the performance of the reflective film of the present invention.
The content ratio of the recycled raw material is not limited, and is preferably 1 to 60% by mass with respect to the mass of the entire reflective layer 1 (relative to 100% by mass of the reflective layer 1), especially 10% by mass or more or More preferably, it is 50% by mass or less. If the content is 10% by mass or more, there will be a cost advantage by using recycled raw materials, and if the content is 50% by mass or less, the light reflectivity and mechanical strength required for the reflective film will not be impaired. It is in.

The reflective layer 1 may have a single layer structure including a thermoplastic resin and a filler. Furthermore, a front and back layer containing a thermoplastic resin may be provided on at least one surface of the layer containing a thermoplastic resin and a filler.
As the thermoplastic resin for the front and back layers, the resins exemplified as the main component resin of the reflective layer 1 can be used, and among them, it is preferable to use a polyolefin resin or a polyester resin as the main component.

The thickness of the reflective layer 1 is preferably 40 μm or more and 200 μm or less.
The thickness of the reflective layer 1 may be increased in order to increase the light reflectance and brightness. However, in order to meet the recent demand for thinner films, it is preferable to make the reflective layer 1 as thin as possible. If the thickness of the reflective layer 1 is 40 μm or more, the reflective film can have high reflectance, while if the thickness of the reflective layer 1 is 200 μm or less, it can have excellent performance despite being thin. It can be a reflective film.
From this viewpoint, the thickness of the reflective layer 1 is preferably 40 μm or more and 200 μm or less, more preferably 50 μm or more, even more preferably 60 μm or more, particularly preferably 70 μm or more, and the upper limit is more preferably 160 μm or less, More preferably, it is 140 μm or less, particularly preferably 120 μm or less.

In addition, when the reflective layer 1 has a multilayer structure having front and back layers, the thickness of the layer containing the thermoplastic resin and the filler is preferably 10% or more, and 20% or more, based on the overall thickness of the reflective layer 1. It is more preferably at least 30%, even more preferably at least 40%. Further, it is preferably 95% or less, more preferably 90% or less. If it is above the lower limit, it tends to ensure excellent lightness and flexibility as well as excellent reflective performance and concealment performance. Moreover, if it is below the said upper limit, there exists a tendency for heat resistance to be ensured.

The reflective layer 1 may have voids inside. By having voids inside, the light reflectance can be further increased.
When the reflective layer 1 has voids, the volume ratio of the voids (porosity) in the reflective layer 1 is preferably 5% or more, more preferably 10% or more, and particularly preferably 20% or more. . When the porosity is 5% or more, the reflectance of the reflective layer 1 is further improved by increasing the area of the interface where the filler with a relatively high refractive index and the air layer with a low refractive index are in direct contact with each other in the resin. can be done. On the other hand, from the viewpoint of mechanical strength and durability of the reflective layer 1, the above-mentioned porosity is preferably 50% or less.
Note that a method for forming voids inside the reflective layer 1 is known. For example, if a filler is added to the thermoplastic resin constituting the reflective layer 1 and a film is formed to form a base film, then the base film is stretched in at least one axis to create voids inside. can be provided. At this time, in order to set the internal porosity of the first reflective layer 1 within a desired range, it is preferable to stretch the film to an area magnification of 5 times or more, more preferably 7 times or more. Moreover, it is preferable to stretch in two axial directions.

The reflective layer 1 preferably has a reflectance of 95% or more for light with a wavelength of 550 nm. More preferably 96% or more, still more preferably 97% or more. If the reflectance of the reflective layer 1 at 550 nm is 95% or more, the reflectance of the reflective film of the present invention having a laminated structure can be set to a sufficiently high value, and the brightness can be increased accordingly.

The transmittance of the reflective layer 1 for light at 550 nm is preferably 1.0% or more.
In the reflective film of the present invention, by providing the reflective layer 1 and the second reflective layer 3 on the side opposite to the reflective use surface of the reflective layer 1, the transmittance of the 550 nm light of the reflective layer 1 is high to some extent. High brightness can be obtained even in the case of high brightness. If the transmittance of the reflective layer 1 to 550 nm light is 1.0% or more, sufficient brightness and reflectance can be obtained due to the synergistic effect with the reflective layer 3.
From this viewpoint, the transmittance of the reflective layer 1 for light at 550 nm is preferably 1.0% or more, and more preferably 1.1% or more. The upper limit is preferably 4.0% or less, more preferably 3.8% or less, further preferably 3.5% or less, particularly preferably 3.1% or less.

The thickness ratio of the reflective layer 1 is preferably 60% or more of the total layer thickness of the reflective film of the present invention.
The reflective film of the present invention has a reflective layer 1 and a second reflective layer 3 on the side opposite to the reflective surface of the reflective layer 1, thereby achieving high brightness even when the overall thickness of the reflective film is thin. Obtainable. From this point of view, if the thickness ratio of the reflective layer 1 is 70% or more of the total layer thickness of the reflective film of the present invention, sufficient brightness and reflectance can be obtained due to the synergistic effect with the reflective layer 3.
From this viewpoint, the thickness ratio of the reflective layer 1 is more preferably 65% or more, and even more preferably 70% or more, of the total layer thickness of the reflective film of the present invention. The upper limit is preferably 99.5% or less, more preferably 99% or less, further preferably 98% or less, particularly preferably 95% or less, and most preferably 90% or less.

<Second reflective layer>
The reflective film of the present invention preferably has a second reflective layer 3 on the back side of the first reflective layer 1, that is, on the opposite side of the reflective use surface of the first reflective layer 1.
The main material of the reflective layer 3 may be resin or metal as long as it has the reflective properties described below. From the viewpoint of cost and reflective properties, it is preferable to use metal as the main material.
In addition, in the present invention, the "main material" means a material having the largest content mass ratio among the materials constituting each layer. For example, it is possible to assume a case where it accounts for 50% by mass or more, especially 80% by mass or more, and especially 90% by mass or more of the constituent components constituting each layer.

The reflective layer 3 whose main material is resin includes, for example, one containing a thermoplastic resin and a filler (for example, the structure exemplified in the first reflective layer 1 above), and a plurality of resin layers having different refractive indexes. For example, a superimposed structure (for example, the structure described in the above-mentioned Patent Document 1, Japanese Unexamined Patent Publication No. 2006-303478, International Publication No. 2013/122025, etc.) can be mentioned.

On the other hand, examples of the reflective layer 3 whose main material is metal include those formed by vapor-depositing metal. However, the formation method is not limited to this. For example, the metal layer may be formed by a vacuum evaporation method, an ionization evaporation method, a sputtering method, an ion plating method, or the like.

As the metal material, any material having a high reflectance can be used without particular limitation. Generally, silver, aluminum, etc. are preferred, and among these, silver is particularly preferred. Alternatively, from the viewpoint of corrosion resistance, it is also preferable to use a silver alloy. For example, silver and Cu, Au, Ni, Pd, Pt, Ru, Rh, In, Al, Si, Mn, Zr, Sn, Bi, Ge, Ti, Cr, Mo, V, Nb, Ta, Hf, W, An alloy with one or more selected from the group consisting of Co and Ge can be mentioned.

The reflective layer 3 whose main material is metal may be a single layer or laminate of metal, a single layer or laminate of metal oxide, or a combination of a single layer of metal and a single layer of metal oxide. It may be a laminate of more than one layer.

When the main material of the reflective layer 3 is resin, its thickness is preferably 40 μm or more and 200 μm or less, more preferably 50 μm or more, even more preferably 60 μm or more, particularly preferably 70 μm or more, and the upper limit is as follows: The thickness is more preferably 160 μm or less, further preferably 140 μm or less, particularly preferably 120 μm or less.
On the other hand, when the main material of the reflective layer 3 is metal, its thickness is preferably 10 nm to 300 nm, although it varies depending on the material forming the layer, the layer forming method, etc., and in particular, it is 20 nm or more or 250 nm or less. is more preferable, and among these, 40 nm or more or 200 nm or less is even more preferable.
If the thickness of the reflective layer 3 is equal to or greater than the above lower limit, sufficient reflectance can be obtained. On the other hand, if the thickness of the reflective layer 3 is equal to or less than the above upper limit, excellent reflectance can be maintained while maintaining production efficiency.

In the reflective film of the present invention, it is also preferable to adjust the ratio between the thickness of the reflective layer 3 and the thickness of the reflective layer 1.
When the main material of the reflective layer 3 is resin, the thickness ratio (X/Y) is 0.1 or more, where the thickness of the reflective layer 3 is X (μm) and the thickness of the reflective layer 1 is Y (μm). It is preferably 10 or less. The lower limit is more preferably 0.2 or more, further preferably 0.3 or more, particularly preferably 0.5 or more, and the upper limit is more preferably 8 or less, still more preferably 5 or less.
On the other hand, when the main material of the reflective layer 3 is metal, the thickness ratio (X/Y) is 5. It is preferably 0×10 ⁻⁵ or more and 7.5×10 ⁻³ or less. The lower limit is more preferably 1.0×10 ⁻⁴ or more, even more preferably 5.0×10 ⁻⁴ or more, particularly preferably 8.6×10 ⁻⁴ or more, and the upper limit is more preferably 5.0×10 ^-3 or less, more preferably 3.0×10 ^-3 or less.

The reflective layer 3 preferably has a reflectance of 50% or more for light with a wavelength of 550 nm. More preferably it is 60% or more, still more preferably 70% or more. When the reflectance of the reflective layer 3 at 550 nm is 50% or more, the reflectance of the reflective film of the present invention having a laminated structure can be set to a sufficiently high value, and the brightness can be increased accordingly.

The transmittance of the reflective layer 3 for light at 550 nm is preferably 1.0% or less.
When the transmittance of the reflective layer 3 for light at 550 nm is 1.0% or less, it is possible to suppress the transmission of light to the side opposite to the surface used for reflection of the reflective film of the present invention, thereby suppressing a decrease in brightness.
From this viewpoint, the transmittance of the reflective layer 3 for light at 550 nm is preferably 0.8% or less, more preferably 0.5% or less, and still more preferably 0.1% or less. On the other hand, the lower limit is not particularly limited and may be 0%.

<Protective layer>
The reflective film of the present invention may include layers other than the first reflective layer 1, the adhesive space layer 2, and the second reflective layer 3. For example, in order to protect the reflective layer 3, it is possible to provide a protective layer 4 on at least one side of the reflective layer 3.

The material forming the protective layer 4 can be used without particular limitation as long as it is transparent and has good adhesion to the reflective layer 3.
Among these, when the main material of the reflective layer 3 is metal, the material forming the protective layer 4 is preferably one that can prevent corrosion of the reflective layer 3. Examples include thermoplastic resins, thermosetting resins, electron beam curable resins, and ultraviolet curable resins. Specifically, amino resins, aminoalkyd resins, acrylic resins, styrene resins, acrylic-styrene copolymers, urea-melamine resins, epoxy resins, fluorine resins, polycarbonates, nitrocellulose, and cellulose acetate. , alkyd resin, rosin-modified maleic acid resin, polyamide resin, etc., or a resin coating consisting of a mixture thereof. Such a paint can be formed by dispersing the resin in a solvent such as water or a solvent.
Moreover, a plasticizer, a stabilizer, and an ultraviolet absorber can also be added as necessary. Note that as the solvent, the same solvents as those normally used for paints can be used.

The protective layer 4 is formed by diluting the above-mentioned paint with a suitable solvent or the like as necessary and applying it to the entire surface of the second reflective layer 3 by a normal coating method such as a gravure coating method, a roll coating method, or a dip coating method. It can be formed by coating and drying (curing in the case of a curable resin).

The thickness of the protective layer 4 is not particularly limited. It is preferably within the range of 0.1 μm to 200 μm. When the thickness of the protective layer is 0.1 μm or more, the surface of the reflective layer 3 can be uniformly coated, and the effect of forming the protective layer can be fully exhibited.

The protective layer 4 can be colored by adding inorganic or organic fine particles. By coloring the protective layer 4, it is possible to prevent some light from leaking from the reflective layer 3.
Moreover, it is possible to prevent the mistake of using the reflective layer 3 as a reflective use surface by mistake, and also to suppress the glare of the reflective layer 3. Furthermore, this protective layer 4 can also be utilized as a printing layer.
From this viewpoint, materials for forming the protective layer 4 include, for example, barium sulfate, barium carbonate, calcium carbonate, gypsum, titanium oxide, silicon oxide, alumina, silica, talc, calcium silicate, magnesium carbonate, carbon black, graphite, Inorganic pigments and acrylics such as copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complexes, complex oxide black pigments, etc. Ink compositions include organic resin particles such as polystyrene, polyurethane, amide, polycarbonate, silicone, urea-formalin, and melamine, metal powder such as aluminum powder, brass powder, and copper powder, pigments, and dyes. It is possible to use premixed and dispersed materials.
The amount of the inorganic or organic fine particles added is preferably 5 to 50% by mass based on the solid content of the protective layer 4, and more preferably 10% by mass or more or 40% by mass or less.

In the present invention, when the protective layer 4 is located on the outermost surface of the reflective film of the present invention on the side opposite to the surface used for reflection, it is preferably constituted by a hard coat layer.
The hard coat layer can more appropriately prevent peeling of the reflective layer 3, physical damage to the film, and corrosion of the reflective layer 3. As specific examples of the hard coat layer, those made of acrylic resin, urethane resin, melamine resin, epoxy resin, organic silicate compound, silicone resin, etc. are preferable, and one or more of these resins is preferably used. It is more preferable to use a composition obtained by curing a composition containing the same. The thickness of the hard coat layer may be appropriately determined in consideration of the scratch resistance and the overall thickness of the protective layer.

<Support layer>
The reflective film of the present invention may have a support layer 5 from the viewpoint of imparting stiffness to the film and improving handleability. When the main material of the second reflective layer 3 is metal, the support layer 5 may be used as a base material for depositing the metal.

As the support layer 5, it is possible to use a transparent plastic substrate. For example, polymethyl (meth)acrylate (PMMA) resin, polycarbonate (PC) resin, methyl methacrylate-styrene copolymer resin (MS resin), polyarylate resin, polysulfone resin, polyethersulfone resin, norbornene resin, and cycloolefin ( It is possible to use a transparent substrate whose main component is at least one of the group consisting of (alicyclic) resins.

The thickness of the support layer 5 is not particularly limited. It is preferably within the range of 1 μm to 200 μm. If the thickness of the support layer 5 is 1 μm or more, the stiffness of the film will be ensured and the handling properties will be good. Furthermore, by adjusting the thickness of the support layer 5 within this range, the overall thickness of the reflective film of the present invention can be adjusted depending on the use and purpose.

The support layer 5, like the protective layer 4, can be colored by adding inorganic or organic fine particles. By coloring the support layer 5, it is possible to prevent some light from leaking from the reflective layer 3.
Moreover, it is possible to prevent the mistake of using the reflective layer 3 as a reflective use surface by mistake, and also to suppress the glare of the reflective layer 3. Furthermore, this support layer 5 can also be utilized as a printing layer.

Examples of materials for forming the support layer 5 include barium sulfate, barium carbonate, calcium carbonate, gypsum, titanium oxide, silicon oxide, alumina, silica, talc, calcium silicate, magnesium carbonate, carbon black, graphite, copper oxide, and dioxide. Inorganic pigments such as manganese, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complexes, complex oxide black pigments, and acrylic and polystyrene pigments. , organic resin particles such as polyurethane-based, amide-based, polycarbonate-based, silicone-based, urea-formalin-based, melamine-based, etc., metal powder such as aluminum powder, brass powder, copper powder, ink compositions such as pigments, dyes, etc. Those mixed and dispersed in advance can be used.
The amount of the inorganic or organic fine particles added is preferably 5 to 50% by mass based on the solid content of the support layer 5, and more preferably 10% by mass or more or 40% by mass or less.

<Anchor coat layer>
The reflective film of the present invention may include, for example, an anchor coat layer 6 as a layer other than the first reflective layer 1, adhesive space layer 2, and second reflective layer 3, as shown in FIGS. 2 and 3. be.
The anchor coat layer 6 is a layer that improves the adhesion between the second reflective layer 3 and the support layer 5.

For example, the reflective layer 3 can be provided on the surface of the support layer 5 by providing the anchor coat layer 6 on the surface of the support layer 5 and then depositing metal on the surface of the anchor coat layer 6 by sputtering or the like. can. That is, the support layer 5 may be provided with the anchor coat layer 6 on the surface on which the reflective layer 3 is provided.
At this time, the anchor coat layer 6 plays the role of reducing the surface roughness on the side where the reflective layer 3 is provided and providing a further effect of improving reflectance. From this point of view, when the anchor coat layer 6 is provided on the support layer 5, the surface roughness (Ra) on the side where the reflective layer 3 is provided is preferably 1.0 μm or less, and preferably 0.7 μm or less. is more preferable, and even more preferably 0.4 μm or less.

The anchor coat layer 6 may be a layer mainly composed of various cured resins or a layer mainly composed of an inorganic oxide (glass, ceramic, etc.). Alternatively, it may be a layer made of a silicon wafer. In particular, from the viewpoint of being easily provided on the surface of the support layer 5, imparting a certain degree of flexibility, and improving adhesion with the second reflective layer 3, as well as being excellent in handling, the anchor coat layer 6 is preferably a layer mainly made of various cured resins, and particularly preferably a layer mainly made of one or more of acrylic resin, polyester resin, melamine resin, and urethane resin.
In addition to the various cured resins and metal oxides described above, the anchor coat layer 6 may contain various known additives within a range that does not impair the effects of the present invention.

The anchor coat layer 6 preferably has a total light transmittance of 80% or more, more preferably 90% or more, so as not to impair the reflectance and brightness of the reflective film of the present invention.

The thickness of the anchor coat layer 6 is preferably 0.1 μm or more and 10 μm or less. The lower limit of the thickness of the anchor coat layer 6 is more preferably 0.2 μm or more, particularly preferably 0.3 μm or more. If the thickness of the anchor coat layer 6 is too small, the surface of the support layer 5 may not be sufficiently smooth. If the thickness of the anchor coat layer 6 is too large, the smoothness may deteriorate due to uneven coating and formation.

<Laminated structure>
As mentioned above, as long as the reflective film of the present invention includes the first reflective layer 1, adhesive space layer 2, and second reflective layer 3 in this order, it is possible to include other layers and other members. be. For example, as described above, a protective layer 4, a support layer 5, an anchor coat layer 6, etc. can be provided as appropriate.

To illustrate the layer structure of the reflective film of the present invention,
first reflective layer 1/adhesive space layer 2/second reflective layer 3,
first reflective layer 1/adhesive space layer 2/second reflective layer 3/protective layer 4,
First reflective layer 1 / adhesive space layer 2 / protective layer 4 / second reflective layer 3 / protective layer 4,
First reflective layer 1/adhesive space layer 2/support layer 5/second reflective layer 3,
First reflective layer 1 / adhesive space layer 2 / support layer 5 / second reflective layer 3 / protective layer 4,
first reflective layer 1/adhesive space layer 2/second reflective layer 3/support layer 5,
First reflective layer 1 / adhesive space layer 2 / protective layer 4 / second reflective layer 3 / support layer 5,
First reflective layer 1 / adhesive space layer 2 / support layer 5 / anchor coat layer 6 / second reflective layer 3,
First reflective layer 1 / adhesive space layer 2 / support layer 5 / anchor coat layer 6 / second reflective layer 3 / protective layer 4,
First reflective layer 1 / adhesive space layer 2 / second reflective layer 3 / anchor coat layer 6 / support layer 5,
First reflective layer 1 / adhesive space layer 2 / protective layer 4 / second reflective layer 3 / anchor coat layer 6 / support layer 5,
Other layer configurations can be mentioned.

In addition, in these layer configurations, it is preferable that the first reflective layer 1 is placed on the side that is irradiated with light. In addition, the reflective film of the present invention may further have other layers between these layers, or a plurality of the first reflective layer 1, second reflective layer 3, protective layer 4, etc. may each be independently provided. It may be composed of layers.

In order to obtain a desired reflectance, the thickness of the reflective film of the present invention is preferably at least 45 μm or more, more preferably 50 μm or more, and even more preferably 60 μm or more. On the other hand, in order to meet the recent demand for thinner films, it is preferable that the film be thinner, and the upper limit is preferably 500 μm or less, more preferably 400 μm or less, more preferably 350 μm or less, and 300 μm or less. It is more preferable that the particle size is 250 μm or less, and even more preferably that the particle size is 250 μm or less.

Each layer of the reflective film of the present invention may contain antioxidants, light stabilizers, heat stabilizers, hydrolysis inhibitors, lubricants, dispersants, ultraviolet absorbers, white pigments, optical brighteners, and others as necessary. may contain additives.

<Characteristics of reflective film>
(reflectance)
In the reflective film of the present invention, the reflectance of light with a wavelength of 550 nm when irradiated with light from the first reflective layer 1 side is preferably 98% or more, more preferably 98.5% or more, and 99% or more. % or more is more preferable. The reflectance at 550 nm has a correlation with the brightness value of the screen display device when used in a backlight, which is a component of a liquid crystal display, for example, and if the reflectance at 550 nm is 98% or more, the brightness value of the screen display device is This also increases the brightness of the liquid crystal display, making it possible to provide sufficient brightness to the liquid crystal display.
Note that the diffuse reflection film and the specular reflection film have different sensitivities in the integrating sphere in the spectrometer, so the absolute values of the reflectances between the two cannot be simply compared.

(Luminance)
The reflective film of the present invention preferably has a relative brightness of 95% or more based on "ESR-100" (trade name) manufactured by 3M Company as a reference (100%).
If the brightness is 95% or more, sufficient brightness can be provided when mounted on a display device for an electronic device.
From this viewpoint, the brightness of the reflective film of the present invention is preferably 97% or more, particularly 97.5% or more, and even more preferably 98% or more.

<Form of the reflective film of the present invention>
The form of the reflective film of the present invention is not particularly limited, and may be, for example, a film, a sheet, a plate, or other forms.
Further, since the reflective film of the present invention is difficult to separate between the first reflective layer 1 and the second reflective layer 3 and has good handling properties, it is also suitable to wind it around a core to form a wound body.

(core)
When the reflective film of the present invention is wound around a core to form a wound body, the term "core" refers to a cylindrical winding core used for winding up a porous film.
The core can be formed of, for example, paper, resin-impregnated paper, acrylonitrile-butadiene-styrene copolymer (ABS resin), FRP, phenol resin, inorganic-containing resin, adhesive, or the like.
The material of the core is not particularly limited. For example, plastics, thermosetting resins, and the like are preferable because they have a small coefficient of thermal expansion, high rigidity, low swelling property against humidity, and excellent windability.
When the core material is paper, desired characteristics can be easily obtained by coating the surface with a resin or the like. Furthermore, from the viewpoint of surface smoothness, it is also preferable that the core is a tube of resin-impregnated paper. Further, when the material of the core is resin, specifically, it can be formed of acrylonitrile-butadiene-styrene copolymer (ABS resin), FRP, phenol resin, inorganic-containing resin, etc.

<Method for manufacturing reflective film>
The method for manufacturing the reflective film of the present invention will be explained below by giving an example. However, it is not limited to the following manufacturing method.

(Production of member provided with first reflective layer 1)
A member provided with the first reflective layer 1 can be manufactured as follows.
First, a filler is blended into a thermoplastic resin, and other additives are blended as needed to prepare a resin composition. Specifically, fillers and the like are added to a thermoplastic resin and mixed using a ribbon blender, tumbler, Henschel mixer, etc., and then kneaded using a single-screw or twin-screw extruder at a temperature higher than the melting point of the resin. A resin composition for a base material can be prepared by: Alternatively, a so-called masterbatch is prepared in advance by blending a filler etc. into a thermoplastic resin at a high concentration, and this masterbatch and resin are mixed to prepare a resin composition for the first reflective layer with a desired concentration. You can also.

Next, the thus obtained resin composition for the first reflective layer is melted and formed into a film. In general, inflation molding or extrusion molding using a T-die is preferably used as a method for molding into a film. Specifically, after drying the resin composition for the base material as necessary, it is supplied to an extruder and heated to a temperature equal to or higher than the melting point of the resin to melt it. Alternatively, the resin composition may be fed to the extruder without being dried. However, when not drying, it is preferable to use a vacuum vent during melt extrusion. Thereafter, the molten resin composition for the first reflective layer is extruded from the slit-shaped discharge port of the T-die and tightly solidified on a cooling roll to form a cast sheet.

The first reflective layer 1 is preferably stretched in at least one axis, and more preferably biaxially. Stretching can be performed using a roll, tenter, air inflation, tubular, mandrel, or the like. For example, after stretching in the MD direction with rolls, it may be stretched in the TD direction with a tenter, or biaxially stretching with a tubular. Next, a white reflective film can be obtained as a member provided with the first reflective layer 1 by performing heat setting as necessary.

(Production of member provided with second reflective layer 3)
On the other hand, a resin coating for the anchor coat layer 6 is applied onto the resin film serving as the support layer 5 and dried or cured. On this anchor coat layer 6, the second reflective layer 3 is formed by vapor depositing the metal. Furthermore, a coating liquid containing, for example, a resin component and inorganic particles is applied onto the second reflective layer 3 and dried or cured to form a protective layer 4, thereby forming a metal thin mirror film.

(Preparation of reflective film)
Next, by a method such as a gravure method, an adhesive composition is applied onto the first reflective layer 1 and dried or cured to provide a plurality of adhesive portions 2B arranged in a dotted manner.
Alternatively, the adhesive composition may be applied onto the metal thin mirror film and dried or cured by a method such as a gravure method, thereby providing a plurality of adhesive portions 2B arranged in a dotted manner. .

Then, a reflective film can be manufactured by dry laminating the resin film of the metal thin film mirror film and the first reflective layer 1 so as to bond them together via the adhesive portion 2B.
The above manufacturing method is an example of a method for manufacturing the reflective film of the present invention.

<Applications of the reflective film of the present invention>
According to the present invention, it is possible to provide a reflective film that has high reflectance, high brightness, and does not peel off during the manufacturing process. Therefore, the reflective film of the present invention can be suitably used as a reflective member of a display device for an electronic device such as a liquid crystal display, for example, as a substitute for conventional expensive multilayer reflective films. In this case, good light reflection characteristics can be ensured without redesigning the LED light source or optical film.
For example, image display devices such as personal computers, televisions (TVs), mobile terminals (PDAs), mobile phones, smartphones, vehicle-mounted image display devices, and specifically, liquid crystal display devices (LCDs), electroluminescence devices, etc. Display devices for various electronic devices such as displays (ELD), plasma display panels (PDP), cathode tube displays (CRT), surface electrolytic displays (SED), electronic paper, transparent screens, LED diffusers, head-up displays, and TVs. It can be used as a component of

＜＜Explanation of words＞＞
In this specification, when "α to β" (α and β are arbitrary numbers), unless otherwise specified, it means "more than or equal to α and less than or equal to β", as well as "preferably larger than α" or "preferably It also includes the meaning of "less than β".
In addition, when it is written as "above α" (α is an arbitrary number), it includes the meaning of "preferably larger than α" unless otherwise specified, and "below or equal to β" (β is an arbitrary number) is included. In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than β".

Generally, "film" refers to a thin, flat product whose thickness is extremely small compared to its length and width, and whose maximum thickness is arbitrarily limited, and which is usually supplied in the form of a roll. (Japanese Industrial Standards JISK6900) Generally, a "sheet" is defined as a flat product that is thin and generally has a small thickness relative to its length and width. However, the boundary between a sheet and a film is unclear, and there is no need to distinguish between the two in terms of the wording in the present invention. Therefore, in the present invention, even when the term ``film'' is used, the term ``sheet'' is included, and the term ``sheet'' is used. "film" shall be included even if

The invention is further illustrated by the following examples. However, the present invention is not limited to the examples shown below.

<Example 1>
(First reflective layer)
A polyolefin white film (manufactured by Mitsubishi Chemical Corporation, trade name "Lumirex II F20"), which was obtained by adding inorganic particles to a polyolefin resin and biaxially stretching the mixture, was used as the first reflective layer.
The light reflectance of the polyolefin white film at a wavelength of 550 nm was 99.2%, and the light transmittance at a wavelength of 550 nm was 1.97%.

(Metal thin mirror film with second reflective layer)
A coating liquid consisting of a resin component was applied onto a 25 μm thick polyethylene terephthalate film (referred to as PET) as a support layer, and dried to form an anchor coat layer.
A thin silver film layer as a second reflective layer was formed on the surface of the anchor coat layer by vacuum heating evaporation.
Furthermore, a coating liquid consisting of a resin component and silica particles was applied onto the silver thin film layer and dried to form a protective layer, thereby obtaining a metal thin mirror film.
The light reflectance of the metal thin mirror film at a wavelength of 550 nm was approximately 90%, and the light transmittance at a wavelength of 550 nm was 0.06%.

(Preparation of reflective film with adhesive space layer)
A polyester resin (manufactured by Toyo Morton Co., Ltd. (trade name) "AD-900") as the main material, an isocyanate curing agent (manufactured by Toyo Morton Co., Ltd. (trade name) "CAT-RT85", and ethyl acetate as a solvent) A two-component curable polyurethane adhesive was prepared by blending the following in a mass ratio of base agent/curing agent/solvent of 10/1.7/3.3.This two-component curable polyurethane adhesive was coated on the first reflective layer by a direct gravure method and dried with hot air to form an adhesive part.At this time, the arrangement and shape of the adhesive part after transfer were determined according to the dot unit area in Table 1. A gravure roll designed to have the following area ratio was used.
Then, by dry laminating the PET of the metal thin mirror film and the adhesive side of the first reflective layer, the first reflective layer/adhesive space layer/support layer (PET)/anchor A film (sample) having a thickness of about 113 μm and having a laminated structure of coating layer/second reflective layer/protective layer was produced.
The obtained film (sample) was subjected to various evaluations shown below, and the results are shown in Table 1.

<Example 2, 3>
A film (sample) was produced in the same manner as in Example 1 except that the type of gravure roll was changed. That is, a film (sample) was produced in the same manner as in Example 1, except that a gravure roll was used that was designed so that the arrangement and shape of the adhesive part were the dot unit area and existing area ratio in Table 1. .
The obtained film (sample) was subjected to various evaluations shown below, and the results are shown in Table 1.

<Comparative example 1>
A film (sample) was produced in the same manner as in Example 1 except that the type of gravure roll was changed. That is, the film (sample ) was created.
The obtained film (sample) was subjected to various evaluations shown below, and the results are shown in Table 1.

<Various evaluations>
Various physical properties and various evaluations of the films (samples) obtained in Examples and Comparative Examples were performed as follows.

[Measurement of average thickness of each layer]
The average thickness of each layer can be determined by cutting the films (samples) obtained in Examples and Comparative Examples in the thickness direction, and observing the cross section using a scanning electron microscope (SEM) (2000x, only the anchor coat layer 30,000x). Then, the thickness of each layer was measured at nine locations, and the average value was calculated, which was taken as the average thickness of each layer. Table 1 shows the thickness (μm) of each layer.

[Dot unit area of adhesive part]
The first reflective layer was peeled off from the films (samples) obtained in Examples and Comparative Examples to expose the adhesive portion of the adhesive space layer. When the surface where the adhesive part was exposed was observed in a plan view using a laser microscope "OPTELICS HYBRID+" (trade name) manufactured by Lasertec Co., Ltd., it was found that the films (samples) of Examples 1 to 3 had approximately circular adhesive parts. Since they had the same size and were arranged at equal intervals over the entire surface of the adhesive space layer, from the image analysis, the maximum diameter of each of the multiple adhesive parts existing within a 10 mm x 10 mm area was measured, and the average of the maximum diameters was calculated. The average area (mm ² ) of the bonded portion was calculated assuming that the shape of the bonded portion was circular. In Table 1, the average area (mm ² ) of this bonded portion is shown as the dot unit area (mm ² ) of the bonded portion. On the other hand, since the film (sample) of Comparative Example 1 was coated with adhesive over the entire surface, the dot unit area was not measured and was written as "-".

[Existence area ratio of adhesive part]
The first reflective layer was peeled off from the films (samples) obtained in Examples and Comparative Examples to expose the adhesive portion of the adhesive space layer. When the surface where the adhesive part was exposed was observed in a plan view using a laser microscope "OPTELICS HYBRID+" (trade name) manufactured by Lasertec Co., Ltd., it was found that the films (samples) of Examples 1 to 3 had approximately circular adhesive parts. Since they had the same size and were arranged at equal intervals over the entire surface of the adhesive space layer, from the image analysis, the maximum diameter of each of the multiple adhesive parts existing within a range of 10 mm x 10 mm was measured, and each The area (mm ² ) of the bonded portion was determined assuming that the shape of the bonded portion was circular. Then, the ratio (%) of the total area of the plurality of bonded parts existing within the entire area (10 mm x 10 mm) was determined. In Table 1, the ratio (%) of the total area of the adhesive part is shown as the area ratio (%) of the adhesive part. On the other hand, since the adhesive was applied to the entire surface of the film (sample) of Comparative Example 1, the area ratio of the adhesive portion was set to 100%.

[Peel strength]
The peel strength was measured using a tensile compression tester "STA-1150" (trade name) manufactured by Orientec Co., Ltd. For the measurement, first, the film (sample) obtained in the Examples and Comparative Examples was cut out into a strip of 15 mm x 200 mm, and a test piece was prepared by peeling the film by 10 mm between the first reflective layer and the protective layer. Each peeled part was held with the grip of the measuring machine with a distance of 115 mm between the chucks, and was pulled at a speed of 300 mm/min by 180° peeling (T-shaped peeling method), and the average value of the tensile stress (gf) in the stable region was calculated. It was defined as peel strength.

[Reflectance]
The reflectance of the films (samples) and the first reflective layer obtained in Examples and Comparative Examples was measured using a spectrophotometer "UV-4000" (trade name) manufactured by Hitachi High-Technologies Corporation. The reflectance calibrated with the plate was measured in the wavelength range of 300 nm to 800 nm (in 0.5 nm increments) under conditions that made it the standard (100%), and the average reflectance in the wavelength of 400 nm to 800 nm and the reflection at the wavelength of 550 nm were calculated. The ratios were calculated and shown in Table 1.

[Light transmittance]
The light transmittance of the metal thin film mirror film provided with the first reflective layer (polyolefin white film) and the second reflective layer used in Examples and Comparative Examples was measured as follows. Using a spectrophotometer "UV-4000" (trade name) manufactured by Hitachi High-Technologies Co., Ltd., the transmittance was calibrated with an alumina standard component plate as the standard (100%), and the polyolefin used in the examples and comparative examples. Transmission of the polyolefin white film and the metal thin mirror film used in the Examples and Comparative Examples in the wavelength range of 300 nm to 800 nm (0.5 nm unit) was achieved by inserting the white film and the mirror film of the metal thin film into the optical path. The light transmittance at a wavelength of 550 nm was determined.

[Luminance]
An edge-light type backlight unit having a rectangular display portion with a short side of 217.5 mm and a long side of 347 mm was used. The films (samples) obtained in the Examples and Comparative Examples were set on the chassis at the bottom of the backlight unit, and then the light guide plate with edge light, the diffusion sheet, and two orthogonal prism sheets were placed on top of it in this order. Ta. After placing the backlight on a flat surface so that the display section faces upward, the edge light is turned on, and a camera (manufactured by Konica Minolta Co., Ltd., model: CA-2000) installed at the top, 73 cm away from the display section, is used. The average brightness of 23 points was measured.
The brightness of a commercially available reflective film ("ESR-100" (trade name) manufactured by 3M Company) was measured in the same way, and the relative value (%) when this value was taken as 100% was calculated for each example and comparative example. Table 1 shows the brightness of the reflective film (sample).

From the above Examples and Comparative Examples as well as tests conducted by the present inventors, it has been found that compared to the case where the first reflective layer and the second reflective layer are laminated together on the entire surface, it is better to adhere the first reflective layer and the second reflective layer partially to create an air layer. It was found that the reflectance and brightness can be increased by combining the two. In particular, it was found that the brightness can be increased.
Note that a structure in which a member including the first reflective layer and a member including the second reflective layer are simply overlapped (100% air layer between the first reflective layer and the second reflective layer) However, the brightness is improved compared to the case where the first reflective layer and the second reflective layer are bonded together over the entire surface (see Example 3 of International Publication 2016/072472). However, when assembling a module using such a reflective film, the member containing the first reflective layer and the member containing the second reflective layer are each independent, which results in poor handling and problems. As a result, scratches may occur due to friction between members, which may cause performance deterioration.
In contrast, the member including the first reflective layer and the member including the second reflective layer are partially bonded by arranging adhesive parts such that a plurality of adhesive parts are scattered in the surface direction. It has been found that by doing so, the reflectance and brightness, especially the brightness, can be increased, and furthermore, it is possible to prevent damage caused by rubbing between members without impairing handling properties. Specifically, it was found that the brightness was improved by about 0.6 to 1.6% compared to the case where the first reflective layer and the second reflective layer were bonded together over the entire surface (solid coating over the entire surface). At this time, it was found that the smaller the area of point adhesion and the larger the air layer between the first reflective layer and the second reflective layer, the greater the brightness improvement effect.

Furthermore, as a result of considering linear, lattice, and dot-like adhesive placement patterns, we found that arranging the adhesive in a linear pattern creates a directionality that makes it easier to peel off, so it is more likely to peel off in that direction during the manufacturing process. It was found that the handling performance was insufficient. Furthermore, it has been found that when the adhesive parts are arranged in a grid pattern, the marks of the adhesive parts become noticeable when viewed from the protective layer side, resulting in poor appearance. On the other hand, by arranging the adhesive parts in dots, in other words, by arranging multiple adhesive parts scattered in the surface direction, it is possible to increase the reflectance and brightness, and furthermore, it is possible to improve the anisotropy in the releasability. It was found that no cracking occurred, and no marks from the bonded portion were noticeable.

In the above example, the PET metal thin film mirror film and the adhesive side of the first reflective layer are bonded together to form the first reflective layer/adhesive space layer/support layer/anchor coat layer/second reflective layer. The reflective film has a laminated configuration of a reflective layer/protective layer, and the protective layer of the metal thin mirror film and the adhesive side of the first reflective layer are bonded together to form the first reflective layer/adhesive space. A reflective film with a laminated structure of layer/protective layer/second reflective layer/anchor coat layer/support layer was prepared and evaluated in the same manner, and the results showed that in this case as well, the reflectance and brightness were increased compared to the comparative example. It was confirmed that there were no problems with peeling. However, the former was able to further increase the reflectance and brightness.

As described above, the effects of the present invention are due to the arrangement and shape of the bonded portion, so the composition and structure of layers other than the bonded space layer, such as the first reflective layer and the second reflective layer, may be changed depending on the embodiment. It is thought that even if it is changed to something other than the above, the same effects as in the above embodiments can be obtained in terms of reflectance, brightness, handling properties, etc.

1 First reflective layer 2 Adhesive space layer 3 Second reflective layer 4 Protective layer 5 Support layer 6 Anchor coat layer

Claims (13)

A first reflective layer, an adhesive space layer, and a second reflective layer are provided in this order, and the adhesive space layer has a space and an adhesive part made of an adhesive composition, and the plurality of adhesive parts are A reflective film that is dotted in the surface direction. The reflective film according to claim 1, wherein the area ratio of the adhesive portion is 1 to 50%. The reflective film according to claim 1, wherein the unit area of the adhesive portion is 0.01 to 0.5 mm ² . The reflective film according to claim 1, wherein the adhesive portion has an average thickness of 1 to 20 μm. The reflective film according to claim 1, wherein the first reflective layer has a light reflectance of 95% or more at a wavelength of 550 nm. The reflective film according to claim 1, wherein the first reflective layer has a light transmittance of 1.0% or more at a wavelength of 550 nm. The reflective film according to claim 1, wherein the first reflective layer contains a polyolefin resin or a polyester resin as a main component resin. The reflective film according to claim 1, wherein the second reflective layer has a light reflectance of 50% or more at a wavelength of 550 nm. The reflective film according to claim 1, wherein the second reflective layer has a light transmittance of 1.0% or less at a wavelength of 550 nm. The reflective film according to claim 1, wherein the second reflective layer is mainly made of metal. The reflective film according to claim 1, further comprising a protective layer on at least one surface of the second reflective layer. A wound body obtained by winding the reflective film according to any one of claims 1 to 11 around a core. A display device for an electronic device, comprising the reflective film according to any one of claims 1 to 11.

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