Field of view control film

Abstract

To provide a field-of-view control film that offers good visibility from the inside to the outside and good privacy protection from the outside to the inside, while also having a superior aesthetic appearance. [Solution] The material comprises an adhesive layer, a substrate layer, and a white fine pattern layer in this order, with a total light transmittance of 70-92%, a haze of 40% or less, an aperture ratio of 40% or more for the white fine pattern layer, and an area of ​​10,000-250,000 μm for each pattern component constituting the white fine pattern layer. 2 This is a field of view control film.

Description

Technical Field

[0001] The present disclosure relates to a vision control film, and particularly to a vision control film for window glass.

Background Art

[0002] As a method of imparting privacy protection and light-shielding functions to window glass of houses and office buildings, it is widely practiced to attach a special vision control (optical control) film to the window glass. There are various types of vision control films. For example, a dimming film having a dimming layer containing a functional liquid crystal material or the like and a visible light absorption layer is known (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When such a vision control film is attached to window glass, due to the polarization function of the film, the inside condition cannot be observed from the outside of the window glass (good privacy protection). On the other hand, from the inside of the window glass, the outside scenery can be viewed in the same way as when there is no vision control film, and the visibility is not obstructed (good visibility).

[0005] However, the color of the vision control film observed from the outside of the window glass is generally black, gray or a similar neutral color, which may impair the aesthetic appearance of houses and office buildings.

[0006] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a vision control film having good visibility from the inside to the outside and good privacy protection from the outside to the inside, and excellent aesthetic appearance. [Means for solving the problem]

[0007] As a result of diligent research by the inventors, they found that providing a layer with a specific white fine pattern on a transparent substrate was important in solving the problem, leading to the development of the field-of-view control film described herein.

[0008] The summary of this disclosure is as follows: [1] comprising an adhesive layer, a substrate layer, and a white fine pattern layer in this order, The total light transmittance is 70-92%. Haze is below 40%, The aperture ratio of the white fine pattern layer is 40% or more, and the area of ​​each pattern component constituting the white fine pattern layer is 10,000 to 300,000 μm². 2 This is a field of view control film. [2] The field of view control film according to [1], wherein the pattern components include square elements with sides of 500 μm or less, and the haze as a field of view control film is 30% or less. [3] The field of view control film according to [1], wherein the pattern components include circular elements with a diameter of 500 μm or less, and the haze as a field of view control film is 40% or less. [4] A field of view control film according to any one of [1] to [3], wherein the total light transmittance of the pattern components is 20 to 55%, and the haze of the pattern components is 90% or more. [5] A field of view control film according to any one of [1] to [4], wherein the total light transmittance of the substrate layer is 80% or more and the haze of the substrate layer is 5% or less. [6] A field of view control film according to any one of [1] to [5], further comprising a surface protective layer on the white fine pattern layer. [7] A field of view control film for window glass, as described in any one of [1] to [6]. [Effects of the Invention]

[0009] This disclosure provides a field-of-view control film that offers good visibility from the inside to the outside and good privacy protection from the outside to the inside, as well as superior aesthetics. Hereafter, "visibility from the inside to the outside" may be simply referred to as "visibility," and "privacy protection from the outside to the inside" may be simply referred to as "privacy protection."

[0010] The field of view control film disclosed herein can demonstrate its excellent effects when applied to transparent window glass of structures such as houses and buildings, or to transparent window glass of vehicles such as automobiles and trains. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a schematic cross-sectional view of a field-of-view control film according to one embodiment of the present disclosure. [Figure 2] Figure 2 shows a white pattern of a field-of-view control film according to one embodiment of the present disclosure. [Figure 3] Figure 3 shows a white pattern of a field-of-view control film according to another embodiment of the present disclosure. [Modes for carrying out the invention]

[0012] Preferred embodiments of this disclosure are described in detail below. However, this disclosure is not limited to the embodiments described below.

[0013] In this disclosure, total light transmittance and haze are values ​​measured and calculated using a haze meter in accordance with JIS K7136:2000. The formulas for calculating total light transmittance and haze are as follows. Total light transmittance τt = (Id + Ip) ÷ I0 × 100 = Diffuse light transmittance τd + Parallel light transmittance τp Diffuse light transmittance τd = Id ÷ I0 × 100 Parallel light transmittance τp=Ip÷I0×100 Haze H = Diffuse light transmittance τd ÷ Total light transmittance τt × 100 (In the formula, I0 represents the incident light intensity from the light source, Id represents the diffuse ray intensity, and Ip represents the parallel ray intensity.)

[0014] (View control film) FIG. 1 is a schematic cross-sectional view of a view control film according to an embodiment of the present disclosure. As shown in the figure, the view control film 10 includes an adhesive layer 4, a base material layer 1, and a white fine pattern layer 2 in this order. The white fine pattern layer 2 is composed of a plurality of pattern components 2a. A white fine pattern is drawn by the plurality of pattern components 2a. The view control film 10 may further include a surface protection layer 3 on the white fine pattern layer 2.

[0015] The view control film 10 can be suitably used for transparent window glass of buildings such as houses and buildings, and transparent window glass of vehicles such as automobiles and trains.

[0016] The view control film 10 can be manufactured, for example, by forming a white fine pattern layer 2 on one surface of the base material layer 1, forming an adhesive layer 4 on the other surface of the base material layer 1, forming a surface protection layer 3 on the white fine pattern layer 2 as necessary, and further protecting the adhesive layer 4 with a release paper, film, etc. as necessary.

[0017] The total light transmittance of the view control film 10 is 70 to 92%. When the total light transmittance is 70% or more, visibility is easily obtained. From this viewpoint, the total light transmittance may be 75% or more, and may be 77% or more. On the other hand, when the total light transmittance is 92% or less, privacy protection is easily obtained. From this viewpoint, the total light transmittance may be 89% or less, and may be 88% or less.

[0018] The haze of the view control film 10 is 40% or less. When the haze is 40% or less, visibility is easily obtained. From this viewpoint, the haze may be 38% or less, and may be 36% or less. The lower limit of the haze is not particularly limited, but considering privacy protection, it can be, for example, 7.0% or more.

[0019] The thickness of the field of view control film 10 is not particularly limited, but setting it to, for example, 25 μm to 300 μm makes it easier to apply to flat surfaces such as window glass.

[0020] (base material layer) The base layer 1 may be a resin substrate or a resin film. Examples of resin components constituting the base layer 1 include polyolefins and polyesters, and from the viewpoint of versatility, polyolefins can be preferably used. Specific examples of resins constituting the base layer 1 include existing resins such as polyethylene, polypropylene, polybutylene, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polyvinyl chloride.

[0021] The substrate layer 1 can be described as a transparent substrate layer. That is, it is preferable that the total light transmittance of the substrate layer 1 is 80% or more. Furthermore, it is preferable that the haze is 5% or less.

[0022] A total light transmittance of 80% or more in the substrate layer 1 makes it easier to obtain visibility as a field-of-view control film. From this viewpoint, the total light transmittance may be 82% or more, or 84% or more. There is no particular upper limit to the total light transmittance, but considering that it is composed of the resin components exemplified above, it can be set to, for example, 90%.

[0023] When the haze of the base layer 1 is 5% or less, visibility as a field-of-view control film is easily obtained. From this viewpoint, the haze may be 4.5% or less, or 4% or less. The lower limit of the haze is not particularly limited, but considering that it is composed of the resin components exemplified above, it can be, for example, 0.2% or more.

[0024] The thickness of the substrate layer 1 may be 20 to 150 μm or 50 to 100 μm, taking into consideration the expression of layer function, printability, cost, etc.

[0025] The substrate layer 1 may be subjected to surface treatments such as corona treatment, plasma treatment, ozone treatment, electron beam treatment, ultraviolet treatment, or dichromate treatment to improve adhesion with adjacent layers. In addition, a primer layer may be provided between the two layers to particularly improve adhesion between the substrate layer 1 and the white fine pattern layer 2.

[0026] Various additives may be added to the base layer 1 as needed, such as fillers, foaming agents, flame retardants, lubricants, antistatic agents, antioxidants, crystal nucleating agents, ultraviolet absorbers, light stabilizers, heat stabilizers, colorants, and matting agents.

[0027] (White fine pattern layer) The white fine pattern layer 2 is a layer provided on one side of the substrate layer 1. As described below, the white fine pattern layer 2 is composed of pattern components 2a formed (drawn) with white pigment. The white fine pattern layer 2 can provide the viewing control film 10 with good aesthetics and privacy protection.

[0028] The aperture ratio of the white fine pattern layer 2 is 40% or more. A 40% or higher aperture ratio of the white fine pattern layer 2 facilitates visibility. From this perspective, the aperture ratio may be 50% or higher, or even 60% or higher. While there is no particular upper limit to the aperture ratio of the white fine pattern layer 2, considering privacy protection, it can be, for example, 90% or less. Here, the aperture ratio is a value calculated from the area of ​​the white fine pattern layer 2 and the total area of ​​each pattern component constituting the white fine pattern layer in a plan view of the white fine pattern layer 2.

[0029] The area of ​​each pattern component 2a constituting the white fine pattern layer 2 (the area of ​​each individual element, not the total area) is between 10,000 and 300,000 μm². 2 The area of ​​pattern component 2a is 10,000 μm². 2 A size greater than this makes it easier to achieve privacy protection. From this perspective, the area in question is 40,000 μm². 2 The above is acceptable, and 90,000 μm 2The above is acceptable. On the other hand, the area of ​​pattern component 2a is 300,000 μm². 2 Visibility is easily achieved if the area is as follows: From this perspective, the area is 250,000 μm². 2 The following may be true, and the size is 200,000 μm. 2 The following is acceptable:

[0030] The total light transmittance of the pattern component 2a is preferably 20-55%. When the total light transmittance of the pattern component 2a is 20% or more, visibility is easily obtained. From this viewpoint, the total light transmittance may be 30% or more, or 40% or more. On the other hand, when the total light transmittance of the pattern component 2a is 55% or less, privacy protection is easily obtained. From this viewpoint, the total light transmittance may be 52% or less, or 51% or less.

[0031] The haze of pattern component 2a may be 90% or more. A haze of 90% or more for pattern component 2a makes it easier to achieve privacy protection. From this perspective, the haze may be 92% or more, or 94% or more. There is no particular upper limit to the haze, but considering that it is composed of the white pigments exemplified below, it can be, for example, 98%.

[0032] The total light transmittance and haze of pattern component 2a can be adjusted, for example, by the amount of white pigment.

[0033] Examples of pattern components 2a include elements having shapes such as circles, ellipses, oblongs, triangles, quadrilaterals (squares), and polygons. Pattern components 2a may include one of these shapes individually, or two or more. However, from the standpoint of pattern design, pattern components 2a may substantially consist of elements of any one shape. "Substantially" includes cases where pattern components are not properly drawn, such as at the edges of the pattern. The size of each shape can be adjusted as appropriate based on the area of ​​the pattern component 2a.

[0034] Specifically, the white fine pattern layer 2 is one in which the pattern component 2a includes square elements with sides of 500 μm or less (preferably 100 μm or more), and the haze as a field of view control film is 30% or less. Alternatively, the white fine pattern layer 2 may be one in which the pattern component 2a includes circular elements with a diameter of 500 μm or less (preferably 100 μm or more), and the haze as a field of view control film is 40% or less.

[0035] Figure 2 shows a white pattern of a field-of-view control film according to one embodiment of the present disclosure. The figure shows a white pattern when the pattern components 2a consist of square elements. In the figure, each pattern component 2a is a square having a predetermined side length and is arranged at equal intervals vertically and horizontally with a certain space s and pitch p.

[0036] Figure 3 shows a white pattern of a field-of-view control film according to one embodiment of the present disclosure. The figure shows a white pattern when the pattern components 2a consist of circular elements. In the figure, each pattern component 2a is a circle having a predetermined diameter and is arranged at equal intervals vertically and horizontally with a certain space s and pitch p.

[0037] In Figures 2 and 3, space s is the distance between adjacent pattern elements 2a, and pitch p is the sum of the width (vertical or horizontal) of space s and pattern elements 2a. As shown in both figures, space s and pitch p may be the same in the vertical and horizontal directions, or they may be different. There are no particular restrictions as long as the area and aperture ratio of the pattern elements are at the desired values, but for example, pitch p is preferably 500 to 1000 μm. A pitch p of 500 μm or more makes it easier to obtain visibility, and a pitch p of 1000 μm or less makes it easier to obtain privacy protection.

[0038] The thickness of the white fine pattern layer 2 (thickness of the pattern component 2a) may be 0.5 to 10 μm or 1 to 5 μm, considering the expression of layer function, opacity, cost, etc.

[0039] The white fine pattern layer 2 can be formed, for example, by printing it onto the substrate layer 1 using an ink. The ink can be water-based (solution type, emulsion type), solvent-based, or solvent-free (monomer, oligomer type), and can be either a one-component type or a two-component type using a curing agent. Methods for curing the printed white fine pattern layer 2 include, for example, heat curing, ultraviolet curing, and electron beam curing.

[0040] For example, if the ink is solvent-based, it mainly contains a white pigment, a binder resin, and a solvent. Examples of white pigments include titanium dioxide (titanium white), zinc oxide (zinc white), lithopone, and lead white, and of these, titanium dioxide is preferably used due to its versatility.

[0041] As the binder resin, nitrated cotton, cellulose, vinyl chloride-vinyl acetate copolymer, polyvinyl butyral, polyurethane, acrylic, polyester, and modified versions thereof can be used individually or in combination of two or more.

[0042] As solvents, ethyl acetate, butyl acetate, methyl ethyl ketone, isopropyl alcohol, propylene glycol monomethyl ether, etc., can be used individually or in combination of two or more.

[0043] The ink may contain, as needed, weathering agents such as ultraviolet absorbers, light stabilizers, and heat stabilizers, as well as flame retardants, antiblocking agents, catalyst scavengers, and various additives such as colorants, light scattering agents, and gloss modifiers, to the extent that the desired effects of this disclosure are not impaired. These additives are generally added in any combination.

[0044] Examples of UV absorbers that can be used include benzotriazole-based, benzoate-based, benzophenone-based, and triazine-based UV absorbers. For example, a hindered amine-based light stabilizer can be used. For example, phenol-based, sulfur-based, phosphorus-based, and hydrazine-based heat stabilizers can be used. For example, aluminum hydroxide, magnesium hydroxide, etc., can be used as flame retardants.

[0045] The printing method for the white fine pattern layer 2 is not particularly limited, but general printing methods such as inkjet printing, screen printing, gravure printing, offset printing, gravure offset printing, and flexographic printing can be used. Of these, inkjet printing, which can accommodate a wide variety of pattern designs, is preferred.

[0046] (Surface protective layer) The surface protection layer 3 is a layer that may be provided on the white fine pattern layer 2, that is, on the white fine pattern layer 2 side of the base layer 1, in order to impart functions such as weather resistance, scratch resistance, stain resistance, and design properties to the field of view control film. The surface protection layer 3 may be formed on the base layer 1 so as to embed the pattern components 2a. Suitable materials for the surface protective layer 3 include, for example, ionizing radiation-curable resins and thermosetting resins.

[0047] As the ionizing radiation-curable resin, known materials such as various monomers and commercially available oligomers can be used. Preferably, polyfunctional monomers such as pentaerythritol triacrylate (PET3A), pentaerythritol tetraacrylate (PET4A), trimethylolpropane triacrylate (TMPTA), and dipentaerythritol hexaacrylate (DPHA), or polyfunctional oligomers such as Shiko UV-1700B (manufactured by Mitsubishi Chemical Corporation), or mixtures thereof, can be used.

[0048] The thermosetting resin is not particularly limited, and for example, polymers having reactive groups such as hydroxyl groups and carboxyl groups, such as various acrylic polymers, various polyesters, various polyethers, various polycarbonates, and various polyurethanes, and curing agents having bifunctional or more isocyanate groups, epoxy groups, etc., can be appropriately selected and used in combination.

[0049] The surface protective layer 3 may optionally contain weathering agents such as UV absorbers, light stabilizers, and heat stabilizers, as well as flame retardants, anti-blocking agents, catalyst scavengers, and various additives such as colorants, light scattering agents, and gloss modifiers, to the extent that the desired effects of this disclosure are not impaired. Examples of these additives can be found in the section on the white fine pattern layer 2.

[0050] For the surface protective layer 3, it is preferable to use a weather-resistant agent, particularly an ultraviolet absorber having a triazine skeleton or a light stabilizer having a NOR-type skeleton. While the various additives mentioned above are generally added in any combination, it is preferable that the surface protective layer 3 contains at least both an ultraviolet absorber having a triazine skeleton and a light stabilizer having a NOR-type skeleton.

[0051] The thickness of the surface protective layer 3 may be 13 to 20 μm or 3 to 15 μm, taking into consideration the expression of layer function, printability, cost, etc.

[0052] The method for forming the surface protective layer 3 is not particularly limited. The above-mentioned material can be liquefied and applied by conventional methods such as gravure coating, microgravure coating, comma coating, knife coating, or die coating, and then cured by a method suitable for the material, such as heat curing or ultraviolet curing.

[0053] (Adhesive layer) The adhesive layer 4 is a layer provided on the other side of the base layer 1 (the side opposite to the side on which the white fine pattern layer 2 is provided). The adhesive layer 4 allows the field of view control film 10 and the window to be bonded tightly together without the inclusion of air bubbles or other contaminants.

[0054] The material constituting the adhesive layer 4 is not particularly limited as long as it is uncolored. For example, any resin material with excellent adhesion to window glass can be appropriately selected from acrylic, urethane, silicone, rubber, and other resin materials. Before bonding to the window, the surface of the adhesive layer 4 may be protected with a release liner such as release paper.

[0055] The thickness of the adhesive layer 4 may be 0.5 to 20 μm, and may be 1 to 10 μm or 2 to 7 μm, taking into consideration the expression of layer function, hydrolysis resistance, printability, cost, etc.

[0056] The method for forming the adhesive layer 4 is not particularly limited. The adhesive layer 4 can be formed by making the above material into an ink and using a conventional coating method such as gravure coating, microgravure coating, comma coating, knife coating, or die coating. [Examples]

[0057] The present disclosure will be further illustrated by the following examples, but the present disclosure is not limited to these examples.

[0058] <Fabrication of field-of-view control film> A 100 μm thick PET film (Toray Lumirror T60, total light transmittance: 89.4%, haze: 3.6%) was prepared as the base layer. A white fine pattern layer, created using Illustrator, was formed on one side of this PET film using an inkjet printer (Roland VersaUV LEF-12). The shape of the pattern components was either a square as shown in Figure 2, or a circle as shown in Figure 3. A white ink containing titanium dioxide was used as the ink.

[0059] Next, a surface protective material (Takelac WS-4000, manufactured by Mitsui Chemicals) was applied to the white fine pattern layer using wire bar coating and cured. The thickness of the surface protective layer after curing was 10 μm.

[0060] Next, an adhesive coating material (Olivine BPW6560, manufactured by Toyo Chem) was applied to the other side of the PET film and dried. The thickness of the adhesive layer after drying was 5 μm.

[0061] <Measurement of optical properties> The various optical properties of the field-of-view control film obtained above were measured using a haze meter (HM-150, manufactured by Murakami Color Technology Laboratory).

[0062] Regarding the optical properties of the pattern components, a 100 mm square solid pattern sample was prepared using the above-mentioned ink, and measurements were performed on this sample.

[0063] The aperture ratio was calculated from the area ratio of the pattern-printed area to the unprinted area.

[0064] <Rating> (Visual field control) The field-of-view control film obtained above was attached to the indoor side of a windowpane via an adhesive layer, and the visibility from indoors to outdoors and the privacy protection from outdoors to indoors were visually evaluated from a distance of 50 cm from the windowpane. The evaluation criteria were as follows. -Visibility- ○: The visibility of outdoor lettering and scenery was good. ×: The visibility of outdoor lettering and scenery was poor. -Privacy Protection- ○: The interior could not be seen. ×: The interior of the building was visible.

[0065] (Aesthetics) The visibility control film obtained above was attached to the indoor surface of a windowpane via an adhesive layer, and its aesthetic appearance from the outside was visually evaluated. In all cases, the windowpane with the visibility control film attached had the same transparency and color tone as the original windowpane and did not detract from the surrounding scenery.

[0066] Table 1 summarizes the details of the field-of-view control films prepared for each example and their evaluation results. In the table, "Size" refers to the length of one side of a square or the diameter of a circle. In the table, "τt" refers to the total light transmittance, and "H" refers to the haze.

[0067] [Table 1] [Industrial applicability]

[0068] The field of view control film according to this disclosure offers good visibility from indoors to outdoors and excellent privacy protection from outdoors, as well as superior aesthetics. Therefore, it can be suitably used in transparent window panes of structures such as houses and buildings, and in transparent window panes of vehicles such as automobiles and trains. [Explanation of Symbols]

[0069] 1...Substrate layer, 2...White fine pattern layer, 2a...Pattern component, 3...Surface protective layer, 4...Adhesive layer, 10...View control film.

Claims

1. The structure comprises an adhesive layer, a substrate layer, and a white fine pattern layer in this order. The total light transmittance is 70-92%. Haze is below 40%, The aperture ratio of the white fine pattern layer is 40% or more, and the area of ​​each pattern component constituting the white fine pattern layer is 10,000 to 300,000 μm². ２ This is a field of view control film.

2. The field of view control film according to claim 1, wherein the pattern components include square elements with sides of 500 μm or less, and the haze as a field of view control film is 30% or less.

3. The field of view control film according to claim 1, wherein the pattern components include circular elements with a diameter of 500 μm or less, and the haze as a field of view control film is 40% or less.

4. The field of view control film according to claim 1, wherein the total light transmittance of the pattern components is 20 to 55%, and the haze of the pattern components is 90% or more.

5. The field of view control film according to claim 1, wherein the total light transmittance of the substrate layer is 80% or more, and the haze of the substrate layer is 5% or less.

6. The field of view control film according to claim 1, further comprising a surface protective layer on the white fine pattern layer.

7. A field of view control film according to claim 1, for use with window glass.

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