Method of using laminate and light diffusion control film

Abstract

To provide a light diffusion control film suppressed in liquefaction and a laminate provided with the light diffusion control film.SOLUTION: Disclosed is a laminate (window film 2) which is used in an environment where external light is radiated. This laminate (window film 2) includes: a light diffusion control film 1 having an internal structure having a plurality of regions having relatively high refractive index in a region having a relatively low refractive index in the film; and an ultraviolet absorbing layer (adhesive layers 22a and 22b containing an ultraviolet absorber) positioned closer to the external light incident side than the light diffusion control film 1. The light diffusion control film 1 contains a hindered amine compound.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a light diffusion control film that can diffuse or transmit incident light depending on the incident angle, and a laminate including the light diffusion control film. [Background technology]

[0002] In recent years, light diffusion control films that can diffuse or transmit incident light depending on the angle of incidence have been known. For example, the use of such light diffusion control films as viewing angle control films that are attached to window glass or touch panels of cash dispensers to protect privacy, light control films for reflective liquid crystal displays, etc., has been considered. In addition, the use of the above-mentioned light diffusion control films as displays that utilize external light, specifically signs and signs, has been considered, for example, by printing characters or images on a surface having light diffusion properties or a specular reflective surface, or by attaching a transparent or semitransparent film on which characters or images are printed to these surfaces.

[0003] As an example of the above-mentioned light diffusion control film, there is a film having an internal structure with a plurality of regions with a relatively high refractive index in a region with a relatively low refractive index. More specifically, there is a light diffusion control film having a louver structure in which a plurality of plate-like regions with different refractive indexes are alternately arranged in any one direction along the film surface, and a light diffusion control film having a column structure in which a plurality of pillars with a relatively high refractive index are arranged in a region with a relatively low refractive index.

[0004] As the light diffusion control film as described above, Patent Document 1 discloses a light diffusion control film obtained by curing a resin composition for a light diffusion control film, which contains a specified urethane (meth)acrylate compound, a specified (meth)acrylic acid ester compound having an aromatic skeleton, and a specified photopolymerization initiator. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6414883 Summary of the Invention [Problem to be solved by the invention]

[0006] The present inventors have found that the above-mentioned light diffusion control film liquefies under certain conditions. Therefore, an object of the present invention is to provide a light diffusion control film in which liquefaction is suppressed and a laminate including the light diffusion control film. [Means for solving the problem]

[0007] In order to achieve the above object, firstly, the present invention provides a laminate used in an environment exposed to external light, the laminate comprising: a light diffusion control film having an internal structure including a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index within the film; and an ultraviolet absorbing layer located on the external light incident side of the light diffusion control film, the light diffusion control film containing a hindered amine compound (Invention 1).

[0008] In the above invention (Invention 1), the light diffusion control film in the laminate having the above configuration contains a hindered amine compound, so that the light diffusion control film is prevented from liquefying even when used over time under an external light irradiation environment.

[0009] In the above invention (Invention 1), it is preferable that the ultraviolet absorbing layer has a light transmittance of 30% or less at a wavelength of 380 nm (Invention 2).

[0010] In the above inventions (Inventions 1 and 2), the content of the hindered amine compound in the light diffusion control film is preferably 0.01% by mass or more and 10% by mass or less (Invention 3).

[0011] In the above inventions (Inventions 1 to 3), it is preferable that the light diffusion control film is obtained from a composition containing a high refractive index component, a low refractive index component having a refractive index lower than that of the high refractive index component, and a hindered amine compound (Invention 4).

[0012] In the above inventions (Inventions 1 to 4), it is preferable that the light diffusion control film contains an ultraviolet absorbing agent (Invention 5).

[0013] In the above inventions (Inventions 1 to 5), the laminate may be a window film (Invention 6).

[0014] In the above invention (Invention 6), it is preferable that an ultraviolet absorbing layer is provided on both sides of the light diffusion control film (Invention 7).

[0015] In the above inventions (Inventions 1 to 5), the laminate may be an external light-utilizing display (Invention 8).

[0016] Secondly, the present invention provides a light diffusion control film that is used in an environment where external light is irradiated, and is used in a laminate comprising a light diffusion control film and an ultraviolet absorbing layer located on the external light incident side of the light diffusion control film, the light diffusion control film having an internal structure comprising a plurality of regions with a relatively high refractive index within a region with a relatively low refractive index within the film, and containing a hindered amine-based compound (Invention 9). Effect of the Invention

[0017] According to the light diffusion control film and laminate of the present invention, liquefaction of the light diffusion control film is suppressed. [Brief description of the drawings]

[0018] [Figure 1] FIG. 1 is a schematic perspective view of the internal structure (column structure) of a light diffusion control film according to one embodiment of the present invention. [Diagram 2]FIG. 11 is a schematic perspective view of the internal structure (louver structure) in a light diffusion control film according to another embodiment of the present invention. [Diagram 3] FIG. 1 is a cross-sectional view of a laminate (window film) according to one embodiment of the present invention. [Figure 4] FIG. 4 is a cross-sectional view of a laminate (external light-utilizing display) according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described. [Light diffusion control film] The light diffusion control film according to one embodiment of the present invention is a light diffusion control film used in a laminate described below, that is, a laminate that is used in an environment where external light is irradiated and includes a light diffusion control film and an ultraviolet absorbing layer located on the external light incident side of the light diffusion control film. The light diffusion control film according to this embodiment has an internal structure that includes a plurality of regions with a relatively high refractive index in a region with a relatively low refractive index within the film, and contains a hindered amine compound. The internal structure is preferably a regular internal structure, and will be described in detail below.

[0020] The present inventors have found that when a conventional light diffusion control film is used in the above laminate, the light diffusion control film liquefies over time under external light irradiation. The light diffusion control film according to the present embodiment contains a hindered amine compound as described above, and is thus prevented from liquefying even when the laminate is used over time under external light irradiation.

[0021] Here, "external light" in this specification refers to light that is incident on an object (here, a laminate) from outside the object, and includes direct sunlight, sky light, light reflected from objects, as well as light from various types of lighting or devices, and also includes light that has passed through translucent materials such as glass and plastic.

[0022] The hindered amine refers to an amine having substituents on both sides of an amino group. The hindered amine compound in the present embodiment is represented by the following general formula (I): [ka] (In the formula, R 1 represents a hydrogen atom or an alkyl group. It is preferable that the compound contains at least one skeleton consisting of the following:

[0023] The hindered amine compound in this embodiment is represented by the formula (I) R 1 However, it is preferably an alkyl group, particularly preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group. That is, the hindered amine compound in this embodiment preferably has an N-alkyl group skeleton, particularly preferably an N-C1 to C4 alkyl group skeleton, and more preferably an N-CH3 skeleton. Hindered amine compounds having such skeletons are excellent in the effect of suppressing liquefaction of the light diffusion control film.

[0024] The hindered amine compound in the present embodiment preferably has one or more skeletons of the above general formula (I), more preferably has 1 to 10 skeletons, particularly preferably has 1 to 7 skeletons, further preferably has 1 to 4 skeletons, and most preferably has 1 to 2 skeletons. The skeleton of the above general formula (I) may be present at the end of the hindered amine compound, may be present at the side chain, or may be present at the end and the side chain. When the hindered amine compound has one or two skeletons of the above general formula (I), it is preferable that they are present at the side chain.

[0025] In addition, when the hindered amine compound has two or more skeletons of the above general formula (I), each R 1 may be the same or different.

[0026] The hindered amine compound in this embodiment is preferably a compound in which an oxygen atom of a -COO- skeleton is bonded to the carbon atom at the 4-position in the skeleton of the above general formula (I).

[0027] The hindered amine compound in the present embodiment is represented by the following structural formula (A): [ka] (In the formula, n is an integer of 1 or more.) or a compound represented by the following structural formula (B): [ka] (In the formula, m is an integer of 1 or more.) It is particularly preferable that the compound is represented by the following formula:

[0028] In the compound represented by the above structural formula (A), n is preferably 1-20, more preferably 3-15, and further preferably 5-10.

[0029] In the compound represented by the structural formula (B), m is preferably 1 to 20, more preferably 3 to 15, and even more preferably 5 to 10. 2 is preferably an alkyl group, particularly preferably an alkyl group having 1 to 4 carbon atoms, and more preferably a methyl group.

[0030] The compound represented by the structural formula (A) and the compound represented by the structural formula (B) can each be used alone, but it is preferable to use them in combination.

[0031] The content of the hindered amine compound in the light diffusion control film according to this embodiment is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, particularly preferably 0.2% by mass or more, and even more preferably 0.4% by mass or more. This makes the liquefaction suppression effect of the light diffusion control film more excellent. On the other hand, the content of the hindered amine compound is preferably 10% by mass or less, more preferably 8% by mass or less, particularly preferably 5% by mass or less, and even more preferably 2% by mass or less. This makes it possible to widen the variation haze angle range of the obtained light diffusion control film.

[0032] The light diffusion control film according to this embodiment is preferably obtained from a composition (hereinafter referred to as "light diffusion control composition C") containing a high refractive index component, a low refractive index component having a refractive index lower than that of the high refractive index component, and a hindered amine compound. The light diffusion control film according to this embodiment is preferably obtained by curing the light diffusion control composition C, and in this case, it is preferable that the high refractive index component and the low refractive index component each have one or two polymerizable functional groups. By using such a light diffusion control composition C, it becomes easier to favorably form the regular internal structure described below.

[0033] The light diffusion control composition C preferably contains a component having an ether bond, and the component having an ether bond is preferably polyether urethane (meth)acrylate. When the light diffusion control film is irradiated with weak ultraviolet light for a long period of time, it is considered that the ether bond in the film constituent is broken, and liquefaction is likely to occur. In the light diffusion control film according to this embodiment, it is presumed that the presence of the hindered amine compound inhibits the scission of the ether bond, and effectively suppresses the occurrence of liquefaction.

[0034] Below, a case will be described in which the light diffusion control composition C contains a high refractive index component, a low refractive index component having a refractive index lower than that of the high refractive index component, and a hindered amine compound, and the high refractive index component and the low refractive index component each have one or two polymerizable functional groups; however, the present invention is not limited to this.

[0035] 1. Each component (1) High refractive index component A preferred example of the high refractive index component is a (meth)acrylic acid ester containing an aromatic ring, and particularly a (meth)acrylic acid ester containing a plurality of aromatic rings. Examples of a (meth)acrylic acid ester containing a plurality of aromatic rings include biphenyl (meth)acrylate, naphthyl (meth)acrylate, anthracyl (meth)acrylate, benzylphenyl (meth)acrylate, biphenyloxyalkyl (meth)acrylate, naphthyloxyalkyl (meth)acrylate, anthracyloxyalkyl (meth)acrylate, benzylphenyloxyalkyl (meth)acrylate, and the like, some of which are substituted with halogen, alkyl, alkoxy, halogenated alkyl, and the like. Among these, biphenyl (meth)acrylate is preferred from the viewpoint of easiness in forming a good regular internal structure, and specifically, o-phenylphenoxyethyl acrylate, o-phenylphenoxyethoxyethyl acrylate, and the like are preferred. In this specification, (meth)acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

[0036] The (weight average) molecular weight of the high refractive index component is preferably 2500 or less, particularly preferably 1500 or less, and more preferably 1000 or less. The (weight average) molecular weight of the high refractive index component is preferably 150 or more, particularly preferably 200 or more, and more preferably 250 or more. When the (weight average) molecular weight of the high refractive index component is in the above range, it becomes easy to form a light diffusion control film having a desired regular internal structure. In addition, when the theoretical molecular weight of the high refractive index component can be specified based on the molecular structure, the (weight average) molecular weight of the high refractive index component refers to the theoretical molecular weight (molecular weight that is not the weight average molecular weight). On the other hand, when the theoretical molecular weight described above is difficult to specify because the high refractive index component is, for example, a polymer component, the (weight average) molecular weight of the high refractive index component refers to the weight average molecular weight obtained as a value calculated in terms of standard polystyrene measured by a gel permeation chromatography (GPC) method. In addition, the measurement method of the weight average molecular weight in this specification refers to the value calculated in terms of standard polystyrene measured by the GPC method.

[0037] The refractive index of the high refractive index component is preferably 1.45 or more, more preferably 1.50 or more, particularly preferably 1.54 or more, and even more preferably 1.56 or more. The refractive index of the high refractive index component is preferably 1.70 or less, particularly preferably 1.65 or less, and even more preferably 1.59 or less. When the refractive index of the high refractive index component is in the above range, it becomes easy to form a light diffusion control film having a desired regular internal structure and light diffusion control ability. In addition, the refractive index in this specification means the refractive index of a predetermined component before curing the light diffusion control composition C, and the refractive index is measured in accordance with JIS K0062:1992.

[0038] The content of the high refractive index component in the light diffusion control composition C is preferably 25 parts by mass or more, particularly preferably 40 parts by mass or more, and more preferably 50 parts by mass or more, relative to 100 parts by mass of the low refractive index component. The content of the high refractive index component in the light diffusion control composition C is preferably 400 parts by mass or less, particularly preferably 300 parts by mass or less, and more preferably 200 parts by mass or less, relative to 100 parts by mass of the low refractive index component. By having the content of the high refractive index component within these ranges, the region derived from the high refractive index component and the region derived from the low refractive index component are present in a desired ratio in the regular internal structure of the light diffusion control film formed. As a result, it becomes easier to form a light diffusion control film having a desired regular internal structure.

[0039] (2) Low refractive index component Preferred examples of the low refractive index component include urethane (meth)acrylate, (meth)acrylic polymers having (meth)acryloyl groups in the side chains, (meth)acryloyl group-containing silicone resins, unsaturated polyester resins, etc., and it is particularly preferable to use urethane (meth)acrylate.

[0040] The urethane (meth)acrylate is preferably formed from (a) a compound containing at least two isocyanate groups, (b) a polyalkylene glycol, and (c) a hydroxyalkyl (meth)acrylate.

[0041] Preferred examples of the compound (a) containing at least two isocyanate groups include aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate, and 1,4-xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate (IPDI) and hydrogenated diphenylmethane diisocyanate, and their biurets, isocyanurates, and further adducts (e.g., xylylene diisocyanate-based trifunctional adducts) which are reactants with low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, alicyclic polyisocyanates are preferred, and alicyclic diisocyanates containing only two isocyanate groups are particularly preferred.

[0042] Preferred examples of the above (b) polyalkylene glycol include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyhexylene glycol, etc., and among these, polypropylene glycol is preferred.

[0043] The weight average molecular weight of the (b) polyalkylene glycol is preferably 2300 or more, particularly preferably 3000 or more, and more preferably 4000 or more. The weight average molecular weight of the (b) polyalkylene glycol is preferably 19500 or less, particularly preferably 14300 or less, and more preferably 12300 or less.

[0044] Preferred examples of the (c) hydroxyalkyl (meth)acrylate include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate.

[0045] The synthesis of the urethane (meth)acrylate using the above-mentioned components (a) to (c) as materials can be carried out according to a conventional method. In this case, the mixing ratio of the components (a) to (c) is preferably a molar ratio of component (a):component (b):component (c)=1-5:1:1-5, particularly preferably a molar ratio of 1-3:1:1-3, from the viewpoint of efficient synthesis of the urethane (meth)acrylate.

[0046] The weight average molecular weight of the low refractive index component is preferably 3000 or more, particularly preferably 5000 or more, and more preferably 7000 or more. The weight average molecular weight of the low refractive index component is preferably 20000 or less, particularly preferably 15000 or less, and more preferably 13000 or less. When the weight average molecular weight of the low refractive index component is in the above range, it becomes easy to form a light diffusion control film having a desired regular internal structure.

[0047] The refractive index of the low refractive index component is preferably 1.59 or less, more preferably 1.50 or less, particularly preferably 1.49 or less, and even more preferably 1.48 or less. The refractive index of the low refractive index component is preferably 1.30 or more, particularly preferably 1.40 or more, and even more preferably 1.46 or more. By having the refractive index of the low refractive index component in the above range, it becomes easy to form a light diffusion control film having a desired regular internal structure and light diffusion control ability.

[0048] (3) Hindered amine compounds The hindered amine compound may be any of those mentioned above. The content of the hindered amine compound in the light diffusion control composition C is the same as the content of the hindered amine compound in the light diffusion control film.

[0049] (4) Ultraviolet absorbers It is preferable that the light diffusion control composition C further contains an ultraviolet absorbing agent, which provides a more excellent effect of suppressing liquefaction of the light diffusion control film.

[0050] Examples of ultraviolet absorbents include benzophenone compounds, benzotriazole compounds, triazine compounds, cyanoacrylates, salicylic acid esters, etc., and one type may be used alone or two or more types may be used in combination.Among the above, benzophenone compounds, benzotriazole compounds, and triazine compounds are preferred, and benzotriazole compounds are particularly preferred.These compounds have good compatibility with the high refractive index component and low refractive index component described above, and also have low coloring.

[0051] Preferred examples of the benzophenone compounds include 2,2-dihydroxy-4-methoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid hydrate, and 2-hydroxy-4-n-octyloxybenzophenone. Preferred examples of benzotriazole compounds include 2-(2-hydroxy-5-t-butylphenyl)-2H-benzotriazole, octyl-3-[3-t-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl]phenyl)propionate, 2-ethylhexyl-3-[3-t-butyl-4-hydroxy-5-(5-chloro-2H-benzotriazol-2-yl]phenyl)propionate, and benzenepropanoic acid-3-(2H-benzotriazol-2-yl)-5-(1,1-dimethylethyl)-4-hydroxy-alkyl ester. Preferred examples of triazine compounds include 2,4-bis[2-hydroxy-4-butoxyphenyl]-6-(2,4-dibutoxyphenyl)-1,3-5-triazine, 2-[4,6-di(2,4-xylyl)-1,3,5-triazin-2-yl]-5-octyloxyphenol, etc. These may be used alone or in combination of two or more.

[0052] The content of the ultraviolet absorbing agent in the light diffusion control composition C is preferably 0.001% by mass or more, more preferably 0.01% by mass or more, particularly preferably 0.02% by mass or more, and even more preferably 0.06% by mass or more. This makes the liquefaction suppression effect of the light diffusion control film more excellent. On the other hand, the content of the ultraviolet absorbing agent is preferably 5% by mass or less, more preferably 1% by mass or less, particularly preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less. This allows the light diffusion control composition C to be cured by ultraviolet irradiation without any problems.

[0053] (5) Other ingredients The light diffusion control composition C may contain other additives in addition to the high refractive index component, the low refractive index component, and the hindered amine compound. Examples of the other additives include a multifunctional monomer (a compound having three or more polymerizable functional groups), a photopolymerization initiator, an antioxidant, an antistatic agent, a polymerization accelerator, a polymerization inhibitor, an infrared absorbing agent, a plasticizer, a diluting solvent, and a leveling agent.

[0054] Among the above-mentioned additives, it is also preferable that the light diffusion control composition C contains a photopolymerization initiator. By containing the photopolymerization initiator in the light diffusion control composition C, it becomes easy to efficiently form a light diffusion control film having a desired regular internal structure.

[0055] Examples of photopolymerization initiators include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2- propyl) ketone, benzophenone, p-phenylbenzophenone, 4,4-diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tertiary butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylamine benzoic acid ester, oligo[2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propane], etc. These may be used alone or in combination of two or more.

[0056] When a photopolymerization initiator is used, the content of the photopolymerization initiator in the light diffusion control composition C is preferably 0.2 parts by mass or more, particularly preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more, relative to 100 parts by mass of the total amount of the high refractive index component and the low refractive index component. The content of the photopolymerization initiator is preferably 20 parts by mass or less, particularly preferably 15 parts by mass or less, and more preferably 10 parts by mass or less, relative to 100 parts by mass of the total amount of the high refractive index component and the low refractive index component. By setting the content of the photopolymerization initiator in the light diffusion control composition C to the above range, it becomes easy to efficiently form a light diffusion control film.

[0057] 2. Preparation of light diffusion control composition The light diffusion control composition C can be prepared by uniformly mixing the above-mentioned high refractive index component, low refractive index component, and hindered amine compound, as well as other additives such as a photopolymerization initiator, if desired.

[0058] During the above mixing, the mixture may be stirred while being heated to a temperature of 40 to 80° C. to obtain a uniform light diffusion-controlling composition C. A dilution solvent may be added and mixed so that the obtained light diffusion-controlling composition C has a desired viscosity.

[0059] 3. Internal structure of light diffusion control film The internal structure of the light diffusion control film in this embodiment has multiple regions with relatively high refractive index within a region with relatively low refractive index, which allows incident light to be diffused or transmitted depending on the incident angle.

[0060] The internal structure of the light diffusion control film in this embodiment is preferably a regular internal structure. Specifically, it is preferably a regular internal structure in which a plurality of regions with a relatively high refractive index extend in a film thickness direction for a predetermined length in a region with a relatively low refractive index. Note that such a regular internal structure is distinguished from a phase separation structure in which one phase exists in another phase without clear regularity and a sea-island structure in which approximately spherical island components exist in a sea component, in that the region with a relatively high refractive index extends in the film thickness direction.

[0061] An example of the regular internal structure is a columnar structure in which a plurality of pillars with a relatively high refractive index stand in a region with a relatively low refractive index in the film thickness direction, while another example is a louver structure in which a plurality of plate-like regions with different refractive indexes are alternately arranged in any one direction along the film surface.

[0062] (1) Column structure Fig. 1 is a perspective view showing the column structure. As shown in Fig. 1, in the column structure 11A, a plurality of pillars 111 having a relatively high refractive index stand in the thickness direction, and are surrounded by a region 112 having a relatively low refractive index. Although Fig. 1 shows the pillars 111 as existing throughout the entire thickness direction of the column structure 11A, the pillars 111 may not exist at least at one of the upper end and the lower end in the thickness direction of the column structure 11A.

[0063] When light is incident on a light diffusion control film having such a column structure 11A, it is emitted from the light diffusion control film while being strongly diffused with a predetermined opening angle when it is within a predetermined range of incident angles. On the other hand, when the incident light is incident at an angle outside the above-mentioned range of incident angles, it is transmitted without being diffused, or is emitted with weaker diffusion than the case of incident light within the range of incident angles. Note that the diffused light generated by the column structure 11A is circular or approximately circular (e.g., elliptical) with a spread in both directions when a contrast medium is placed parallel to the surface of the light diffusion control film. On the other hand, in the case of the weak diffusion caused by incident light outside the above-mentioned range of incident angles, it becomes crescent-shaped diffused light.

[0064] In the column structure 11A, the difference in refractive index between the columns 111 having a relatively high refractive index and the regions 112 having a relatively low refractive index is preferably 0.01 to 0.3.

[0065] The above-mentioned columnar object 111 preferably has a structure in which the diameter expands from one surface to the other surface of the light diffusion control film. The columnar object 111 having such a structure is easier to change the traveling direction of light parallel to the axis direction of the columnar object compared to a columnar object whose diameter does not change from one surface to the other surface, and this enables the light diffusion control film to effectively diffuse light.

[0066] Furthermore, the maximum diameter of the cross section of the columnar object 111 cut on a plane horizontal to the axial direction is preferably 0.1 to 10 μm. The cross-sectional shape of the columnar object 111 cut on a plane perpendicular to the axial direction is not particularly limited, but is preferably, for example, a circle, an ellipse, a polygon, an irregular shape, or the like.

[0067] In the column structure 11A, the distance between adjacent columns 111 is preferably 0.1 to 10 μm.

[0068] In the column structure 11A, the columns 111 may stand horizontally in the thickness direction of the light diffusion control film, or may stand at a constant inclination angle. The inclination angle when standing at a constant inclination angle, that is, the acute angle between the axis of the columns 111 of the column structure 11A and the normal to the surface of the light diffusion control film, is preferably 1 to 50°.

[0069] The dimensions and predetermined angles of the regular internal structure of the column structure 11A can be measured by observing a cross section of the column structure 11A using an optical digital microscope.

[0070] (2) Louver structure Fig. 2 is a perspective view showing the louver structure. As shown in Fig. 2, in louver structure 11B, plate-like regions 113 having a relatively high refractive index are alternately arranged in one direction along the film surface, and regions 114 having a relatively low refractive index are filled between them. Note that, although Fig. 2 shows plate-like regions 113 existing throughout the entire thickness direction of louver structure 11B, plate-like regions 113 may not exist at least at one of the upper end and lower end in the thickness direction of louver structure 11B.

[0071] Light incident on a light diffusion control film having such a louver structure 11B is either diffused as it leaves the light diffusion control film or passes through without being diffused, depending on the angle of incidence. The light diffusion control film having the louver structure 11B has the property that light is easily diffused in a direction perpendicular to the arrangement direction of the plate-like regions 113.

[0072] In louver structure 11B, the difference in refractive index between plate-like region 113 having a relatively high refractive index and region 114 having a relatively low refractive index is preferably 0.01 to 0.3.

[0073] In louver structure 11B, the thickness (width in the arrangement direction) of each plate-like region 113 is preferably 0.1 to 10 μm.

[0074] In the louver structure 11B, the plate-like regions 113 may be inclined along their arrangement direction, or may be arranged so as to coincide with the film normal direction without inclination. When inclined along the arrangement direction, the inclination angle, i.e., the acute angle between one surface of the plate-like region 113 and the normal to the light diffusion control film, is preferably 1 to 60°.

[0075] The dimensions and predetermined angles related to the internal structure of louver structure 11B can be measured by observing a cross section of louver structure 11B using an optical digital microscope.

[0076] (3) Other internal structures The internal structure of the light diffusion control film according to this embodiment may have a structure other than the column structure 11A and the louver structure 11B described above. For example, the light diffusion control film may have an internal structure in which the columnar object 111 in the column structure 11A described above is bent in the middle of the thickness direction of the light diffusion control film. The light diffusion control film may have an internal structure in which the plate-shaped region 113 in the louver structure 11B described above is bent in the middle of the thickness direction of the light diffusion control film. Furthermore, the internal structure of the light diffusion control film according to this embodiment may have two or more regions of the columnar object 111 or plate-shaped regions 113 with different inclination angles, different bending angles, or different bends in the thickness direction of the light diffusion control film. Alternatively, the light diffusion control film according to this embodiment may have an internal structure in which the columnar structure 11A and the louver structure 11B, or the above-mentioned bent structures are laminated in any combination.

[0077] (4) The ratio of the internal structure in the thickness direction of the light diffusion control film As described above, the light diffusion control film according to the present embodiment preferably has an internal structure in which a plurality of regions with a relatively high refractive index extend in the thickness direction within a region with a relatively low refractive index. Here, the ratio of the internal structure extending in the thickness direction is preferably 10% or more of the thickness of the light diffusion control film, more preferably 30% or more, and particularly preferably 50% or more, from the viewpoint of making the light diffusion more efficient. Note that there is no restriction on the upper limit, and the internal structure may be formed in 100%, that is, in the entire thickness direction.

[0078] 4. Physical properties of light diffusion control film (1) Thickness The thickness of the light diffusion control film according to the present embodiment is preferably 20 μm or more as a lower limit, particularly preferably 40 μm or more, and more preferably 60 μm or more. When the lower limit of the thickness of the light diffusion control film is as above, it becomes easy to exhibit the desired light diffusion control ability. In addition, the upper limit of the thickness of the light diffusion control film is preferably 700 μm or less, particularly preferably 400 μm or less, and more preferably 200 μm or less. When the upper limit of the thickness of the light diffusion control film is as above, it becomes easy to suppress the occurrence of dents and crushing.

[0079] (2) Variable haze angle range When the internal structure of the light diffusion control film is the above-mentioned column structure 11A or a modified structure thereof, the threshold value is set to 90% of the maximum haze value measured when light is irradiated onto one surface of the diffusion film at an incident angle of -70° to 70°, with the normal direction of that surface being 0°, and it is preferable that the angle range of incident angles (variable haze angle range) showing a haze value equal to or greater than the threshold value is 5 to 100°.

[0080] In addition, when the internal structure of the light diffusion control film is the louver structure 11B described above or a modified structure thereof, 60% of the maximum haze value measured when a light beam is irradiated on one surface of the diffusion film at an incident angle of -70° to 70° with the normal direction of the surface being 0° is set as a threshold value, and the angle range of the incident angle (variable haze angle range) showing a haze value equal to or greater than the threshold value is preferably 5° or more, particularly preferably 10° or more, and more preferably 30° or more. When the variable haze angle range is 5° or more, the angle range of the incident light that can achieve good light diffusion control ability becomes wider. The upper limit of the variable haze angle range is not particularly limited, and may be, for example, 100° or less, particularly 80° or less, or even 50° or less.

[0081] Details of the method for measuring the variable haze angle range are as described in the test examples described later.

[0082] 5. Manufacturing method of light diffusion control film The manufacturing method of the light diffusion control film according to the present embodiment is not particularly limited, and it can be formed by a conventionally known method. For example, the composition for the light diffusion control film described above, preferably the light diffusion control composition C, is applied to one side of a process sheet to form a coating film. The coating film is irradiated with active energy rays to be cured, thereby forming a light diffusion control film. In addition, before or after the irradiation of the active energy rays, one side (particularly the release surface) of a release sheet may be attached to the surface of the coating film opposite to the process sheet, and the coating film may be irradiated with active energy rays through the process sheet or the release sheet to cure the coating film.

[0083] Examples of the coating method include knife coating, roll coating, bar coating, blade coating, die coating, and gravure coating. The light diffusion control composition C may be diluted with a solvent as necessary.

[0084] The active energy rays refer to electromagnetic waves or charged particle beams having an energy quantum, and specific examples thereof include ultraviolet rays, electron beams, etc. Among active energy rays, ultraviolet rays are particularly preferred because they are easy to handle.

[0085] The coating film is irradiated with active energy rays in different modes depending on the internal structure to be formed. For example, when forming the above-mentioned column structure 11A, the coating film is irradiated with parallel light having a high degree of parallelism. Here, parallel light means that the emitted light direction is substantially parallel light that does not spread regardless of the direction from which it is viewed. Such parallel light can be prepared using known means such as a lens or a light-shielding member. During irradiation, it is preferable to irradiate the above parallel light while moving the laminate of the coating film and the process sheet in its longitudinal direction using a conveyor or the like. It is also possible to adjust the inclination angle of the columnar object 111 formed in the column structure 11A by adjusting the irradiation angle of the above parallel light.

[0086] When forming the column structure 11A using ultraviolet rays as the active energy rays, the irradiation conditions are as follows: peak illuminance on the coating surface is 0.1 to 10 mW / cm 2 The peak irradiance here means the measured value at the portion where the active energy ray irradiated to the coating film surface shows the maximum value. Furthermore, the integrated light amount on the coating film surface is preferably 5 to 200 mJ / cm. 2 It is preferable to set the above.

[0087] When the column structure 11A is formed using ultraviolet rays as the active energy rays, the relative moving speed of the light source of the active energy rays with respect to the laminate is preferably 0.1 to 10 m / min.

[0088] On the other hand, when forming the louver structure 11B described above, a linear light source is used as a source of active energy rays, and strip-like (almost linear) light that is random in the width direction (TD direction) and approximately parallel in the flow direction (MD direction) is irradiated onto the laminate surface. Note that the inclination angle of the plate-like region 113 formed in the louver structure 11B can also be adjusted by adjusting the irradiation angle of the light.

[0089] When ultraviolet rays are used as the active energy rays to form the louver structure 11B, the irradiation conditions are as follows: a peak illuminance on the coating surface is 0.1 to 50 mW / cm 2 Furthermore, it is preferable that the integrated light amount on the coating surface is 5 to 300 mJ / cm. 2 In addition, the relative moving speed of the light source of the active energy rays with respect to the laminate is preferably 0.1 to 10 m / min.

[0090] From the viewpoint of completing the curing more reliably, it is also preferable to irradiate the coating with normal active energy rays (active energy rays that have not been converted into parallel or band-like light, scattered light) after curing using the above-mentioned parallel light or band-like light. At this time, from the viewpoint of uniform curing, a release sheet may be laminated on the coating surface.

[0091] [Laminate] A laminate according to one embodiment of the present invention is a laminate used in an environment exposed to external light, and comprises a light diffusion control film having an internal structure including a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index within the film, and an ultraviolet absorbing layer located on the external light incident side of the light diffusion control film, wherein the light diffusion control film contains a hindered amine compound.

[0092] The laminate having the above-mentioned configuration prevents the light diffusion control film from liquefying even when used over time under an external light irradiation environment, and also prevents the light diffusion control film from yellowing. If there is no ultraviolet absorbing layer on the external light incident side of the light diffusion control film, the problem of liquefaction of the light diffusion control film does not occur, and only yellowing becomes a problem.

[0093] The light diffusion control film in the laminate according to this embodiment is the light diffusion control film according to the embodiment described above.

[0094] The light transmittance of the ultraviolet absorbing layer at a wavelength of 380 nm is preferably 30% or less, more preferably 10% or less, particularly preferably 1% or less, further preferably 0.1% or less, and most preferably 0.05% or less. On the other hand, the lower limit of the light transmittance is not particularly restricted, and is preferably 0%. In addition, from the viewpoint of compatibility with high transmittance in the visible light region, it is preferably 0.001% or more, more preferably 0.005% or more, particularly preferably 0.010% or more, and further preferably 0.015% or more. When the light transmittance of the ultraviolet absorbing layer at a wavelength of 380 nm is in the above range, the conventional light diffusion control film is easily liquefied over time under an external light irradiation environment. This is thought to be due to the fact that the light diffusion control film is irradiated with weak ultraviolet light for a long period of time, causing a certain molecular chain in the light diffusion control film to be cut. On the other hand, when the light transmittance of the ultraviolet absorbing layer at a wavelength of 380 nm is within the above range, even if the content of the hindered amine compound is small, yellowing of the light diffusion control film can be suppressed and other components of the laminate can be protected from ultraviolet rays.

[0095] The ultraviolet absorbing layer in this embodiment preferably has high transmittance of light in the visible light region. From this viewpoint, the light transmittance of the ultraviolet absorbing layer at a wavelength of 480 nm is preferably 60% or more, particularly preferably 80% or more, and more preferably 86% or more. From the same viewpoint, the light transmittance of the ultraviolet absorbing layer at a wavelength of 580 nm is preferably 60% or more, particularly preferably 80% or more, and more preferably 86% or more. On the other hand, the upper limit of the light transmittance of the ultraviolet absorbing layer at a wavelength of 480 nm and the upper limit of the light transmittance of the ultraviolet absorbing layer at a wavelength of 580 nm are not particularly restricted, and are preferably 100%. From the viewpoint of compatibility with low transmittance in the ultraviolet light region, it is preferably 99% or less, and more preferably 98% or less.

[0096] The ultraviolet absorbing layer may be a pressure-sensitive adhesive layer containing an ultraviolet absorbing agent, a plastic film containing an ultraviolet absorbing agent, or a combination of these with each other, or a combination with another layer not containing an ultraviolet absorbing agent.

[0097] When the ultraviolet absorbing layer is a pressure-sensitive adhesive layer containing an ultraviolet absorbent, the type of pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is not particularly limited, and can be a conventionally known one.For example, as the pressure-sensitive adhesive, acrylic pressure-sensitive adhesive, silicone pressure-sensitive adhesive, urethane pressure-sensitive adhesive, rubber pressure-sensitive adhesive, etc. can be used, and among them, acrylic pressure-sensitive adhesive, which is easy to achieve good adhesion and transparency, is preferred.As the plastic film containing an ultraviolet absorbent, the type of plastic is not particularly limited, and can be a conventionally known one.

[0098] The ultraviolet absorbing agent in the ultraviolet absorbing layer is not particularly limited, and the same ultraviolet absorbing agents that can be contained in the light diffusion control composition C described above can be used.

[0099] The laminate according to the present embodiment can be used in various applications that require control of light diffusion under an environment of external light irradiation. Examples of the laminate include a viewing angle control film that is attached to window glass, a display of a cash dispenser, a monitor of a personal computer, a display of a smartphone, etc. to protect privacy; a light control film used in a reflective liquid crystal display, etc.; and an external light-utilizing display such as a signboard or a sign. Among the above, the laminate can be suitably used in a window film that is attached to window glass, etc. for the purpose of controlling the viewing angle, an external light-utilizing display, etc.

[0100] When the laminate according to the present embodiment is used as a window film to be attached to a window glass, it is also preferable to provide an ultraviolet absorbing layer on both sides of the light diffusion control film. This absorbs both the ultraviolet rays from sunlight and the ultraviolet rays from indoor lights, effectively suppressing yellowing of the light diffusion control film and protecting desired members from ultraviolet rays. Even with the above configuration, conventional light diffusion control films become liquefied over time.

[0101] Here, the physical properties relating to the color of the laminate according to this embodiment will be described. (1)XYZ(Yxy) color system The lightness Y of the laminate according to this embodiment, as defined by the CIE 1931 XYZ (Yxy) color system, is preferably 40 or more, more preferably 50 or more, and even more preferably 60 or more. The upper limit of the lightness Y is not particularly restricted and may be 100, but is usually about 90 or less. By setting the lower limit of the lightness Y of the laminate as described above, the visibility of objects behind the laminate and the visibility of the decorative layer of the laminate are improved. The lightness Y is determined by irradiating the laminate with ultraviolet light for 1000 hours (irradiance: 75 to 700 W / m 2 ) is also preferably within the above range.

[0102] The chromaticity x of the laminate according to this embodiment, as defined by the CIE1931XYZ (Yxy) color system, is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. The chromaticity x is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.4 or less. On the other hand, the chromaticity y of the laminate according to this embodiment, as defined by the CIE1931XYZ (Yxy) color system, is preferably 0.1 or more, more preferably 0.2 or more, and even more preferably 0.3 or more. The chromaticity y is preferably 0.8 or less, more preferably 0.6 or less, and even more preferably 0.4 or less. Since the chromaticity x and chromaticity y of the laminate are within the above ranges, the laminate can be said to have little coloring and excellent colorlessness. The chromaticity x and chromaticity y are measured by irradiating the laminate with ultraviolet light for 1000 hours (irradiance: 75 to 700 W / m 2 ) is also preferably within the above range.

[0103] (2)L*a*b* color system The lightness L* of the laminate according to this embodiment, as defined by the CIE1976 L*a*b* color system, is preferably 60 or more, more preferably 70 or more, and even more preferably 80 or more. On the other hand, there is no particular restriction on the upper limit of the lightness L*, and it may be 100, but it is usually about 98 or less. By setting the lower limit of the lightness L* of the laminate as described above, the visibility of objects behind the laminate and the visibility of the decorative layer of the laminate are improved. Note that this lightness L* is determined by irradiating the laminate with ultraviolet light for 1000 hours (irradiance: 75 to 700 W / m 2 ) is also preferably within the above range.

[0104] The absolute value of the chromaticity a* of the laminate according to this embodiment, as defined by the CIE1976L*a*b* color system, is preferably 20 or less, more preferably 10 or less, and even more preferably 8 or less. On the other hand, the absolute value of the chromaticity a* is not particularly restricted, and is preferably 0. On the other hand, the absolute value of the chromaticity b* of the laminate according to this embodiment, as defined by the CIE1931XYZ(Yxy) color system, is preferably 40 or less, more preferably 30 or less, and even more preferably 25 or less. On the other hand, the absolute value of the chromaticity b* is not particularly restricted, and is preferably 0. Since the upper limits of the chromaticity a* and chromaticity b* of the laminate are as described above, the laminate can be said to have little coloring and excellent colorless transparency. The chromaticity a* and chromaticity b* are measured by irradiating the laminate with ultraviolet light for 1000 hours (irradiance: 75 to 700 W / m 2 ) is also preferably within the above range.

[0105] In the laminate according to this embodiment, ultraviolet light was irradiated for 1000 hours (irradiance: 75 to 700 W / m 2 ) Δb*, which is the difference in chromaticity b* before and after the exposure, is preferably 40 or less, more preferably 30 or less, and particularly preferably 20 or less. This means that yellowing due to ultraviolet irradiation is effectively suppressed.

[0106] (3)Yellowness / Yellowness The absolute value of the yellowness index YI defined by JIS K7373:2006 of the laminate according to this embodiment is preferably equal to or less than 60, more preferably equal to or less than 50, and particularly preferably equal to or less than 40. This means that the laminate has a small yellowness index and an excellent degree of colorlessness.

[0107] In addition, the laminate according to this embodiment was irradiated with ultraviolet light for 1000 hours (irradiance: 75 to 700 W / m 2) and after the irradiation, ΔYI, is preferably 50 or less, more preferably 40 or less, and particularly preferably 30 or less. This means that yellowing due to ultraviolet irradiation is well suppressed.

[0108] Below, specific examples of the laminate according to this embodiment will be described using a window film as a viewing angle control film and an external light-utilizing display (e.g., a station sign), but the laminate according to the present invention is not limited to these.

[0109] 1. Window Film A window film as an example of the laminate according to this embodiment is shown in Fig. 3. As shown in Fig. 3, the window film 2 in this embodiment is configured to include, from the top in the figure, a transparent resin film 21a with a hard coat layer 211, a pressure-sensitive adhesive layer 22a containing an ultraviolet absorbing agent, a transparent resin film 21b, a light diffusion control film 1, a transparent resin film 21c, and a pressure-sensitive adhesive layer 22b containing an ultraviolet absorbing agent.

[0110] The window film 2 in this embodiment is attached to a window glass 20 or the like via an adhesive layer 22b containing an ultraviolet absorbing agent. In this embodiment, the window film 2 is attached to the inside of the window glass 20, and therefore, sunlight enters the window film 2 through the window glass 20. However, the window film 2 may also be attached to the outside of the window glass 20.

[0111] The light diffusion control film 1 is the light diffusion control film 1 according to the embodiment described above. In the window film 2 in this embodiment, the internal structure of the light diffusion control film 1 is preferably a louver structure 11B or a modified structure thereof, but is not limited thereto.

[0112] In the window film 2 in this embodiment, the pressure-sensitive adhesive layer 22a containing an ultraviolet absorbing agent and the pressure-sensitive adhesive layer 22b containing an ultraviolet absorbing agent each correspond to an ultraviolet absorbing layer. That is, in this embodiment, the ultraviolet absorbing layers are present on both sides of the light diffusion control film 1.

[0113] The thickness of the pressure-sensitive adhesive layer 22a, 22b containing the ultraviolet absorber is not particularly limited as long as it exerts the desired adhesive strength and satisfies the light transmittance at a wavelength of 380 nm described above. In general, the thickness is preferably 1 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more. The thickness is preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 30 μm or less.

[0114] The material of the transparent resin films 21a, 21b, and 21c can be appropriately selected from known transparent resin films, and may be the same material or different materials. Examples of such transparent resin films include films made of polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly-1-butene; polycarbonate resins; polyvinyl chloride resins; polyethersulfone resins; polyethylene sulfide resins; styrene resins; acrylic resins; polyamide resins; cellulose resins such as cellulose acetate, and the like, or laminated films thereof, among which polyester films, particularly polyethylene terephthalate films, are preferred.

[0115] Any one or more of the transparent resin films 21a, 21b, and 21c may contain an ultraviolet absorbing agent. In this case, the transparent resin film and the pressure-sensitive adhesive layers 22a and 22b containing the ultraviolet absorbing agent also serve as an ultraviolet absorbing layer in this embodiment.

[0116] The hard coat layer 211 can be formed of a known material, and the thickness thereof is not particularly limited and can be a general thickness.

[0117] The window film 2 in the present embodiment can be produced by a conventionally known method, and is not particularly limited.

[0118] When the window film 2 in this embodiment is attached to a window glass, the viewing angle can be controlled so that when the window film 2 is viewed from a certain angle, the other side of the window film 2 can be seen, and when the window film 2 is viewed from another angle, the other side of the window film 2 cannot be seen.

[0119] 2.Display using natural light An external light-utilizing display body (for example, a station sign) is shown in Fig. 4 as an example of the laminate according to this embodiment. As shown in Fig. 4, the external light-utilizing display body 3 in this embodiment is configured to include, from the top in the figure, a transparent resin film 31a, an adhesive layer 32a containing an ultraviolet absorbing agent, a decorative layer 33, a transparent resin film 31b, an adhesive layer 32b containing an ultraviolet absorbing agent, a transparent resin film 31c, a light diffusion control film 1, a transparent resin film 31d, an adhesive layer 34a, a reflective layer 35, a transparent resin film 31e, and an adhesive layer 34b. The transparent resin film 31c and / or the transparent resin film 31d may be omitted.

[0120] The ambient light display body 3 in this embodiment is attached to a base material (frame member) 30 or the like via an adhesive layer 34b. In this embodiment, sunlight enters the ambient light display body 3 from above in the figure, that is, from the transparent resin film 31a side.

[0121] The light diffusion control film 1 is the light diffusion control film 1 according to the embodiment described above. In the external light utilization type display 3 in this embodiment, the internal structure of the light diffusion control film 1 is preferably a column structure 11A or a modified structure thereof (for example, a two-layer structure of a bent column structure having a columnar object bent midway and a columnar object having a linear columnar object), but is not limited thereto.

[0122] In the external light display 3 of this embodiment, the adhesive layer 32a containing an ultraviolet absorbing agent and the adhesive layer 32b containing an ultraviolet absorbing agent each correspond to an ultraviolet absorbing layer. Therefore, in this embodiment, at least two ultraviolet absorbing layers are present on the external light incident side of the light diffusion control film 1.

[0123] The thickness of the pressure-sensitive adhesive layer 32a, 32b containing the ultraviolet absorber is not particularly limited as long as it exerts the desired adhesive strength and satisfies the light transmittance at a wavelength of 380 nm described above. In general, the thickness is preferably 1 μm or more, more preferably 5 μm or more, particularly preferably 10 μm or more, and even more preferably 15 μm or more. The thickness is preferably 100 μm or less, more preferably 50 μm or less, and particularly preferably 30 μm or less.

[0124] The material of the transparent resin films 31a, 31b, 31c, 31d, and 31e can be appropriately selected from known transparent resin films, and may be the same material or different materials. Examples of such transparent resin films include polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, poly(4-methyl-1-pentene), and poly-1-butene; polycarbonate resins; polyvinyl chloride resins; polyethersulfone resins; polyethylene sulfide resins; styrene resins; acrylic resins; polyamide resins; cellulose resins such as cellulose acetate; and fluorine resins, or laminated films thereof.

[0125] Among the above, the transparent resin film 31a is preferably a fluorine-based resin film having excellent light resistance. The surface of the transparent resin film 31a facing the outside light may be glossy or matte. The transparent resin films 31b and 31e are preferably polyvinyl chloride film or polyethylene terephthalate film. The transparent resin films 31c and 31d are preferably polyester film, particularly polyethylene terephthalate film.

[0126] Any one or more of the transparent resin films 31a, 31b, 31c, and 31d may contain an ultraviolet absorbing agent, and it is particularly preferable that the transparent resin films 31a and 31b contain an ultraviolet absorbing agent. In this case, the transparent resin films, together with the pressure-sensitive adhesive layers 32a and 32b containing the ultraviolet absorbing agent, also serve as ultraviolet absorbing layers in this embodiment.

[0127] From the viewpoint of achieving both ultraviolet absorbing properties and visible light transmitting properties, the thickness of the transparent resin films 31a and 31b containing an ultraviolet absorbing agent is preferably 10 μm or more, more preferably 50 μm or more, and even more preferably 80 μm or more. From the same viewpoint, the thickness is preferably 1000 μm or less, more preferably 500 μm or less, and even more preferably 200 μm or less.

[0128] The decorative layer 33 is not particularly limited as long as it can express the display contents by characters, patterns, etc. and does not impede the desired light diffusion effect, and any conventionally known layer can be used. For example, the decorative layer 33 may be formed by printing ink constituting characters, patterns, etc. on the surface of the transparent resin film 31b.

[0129] The thickness of the decorative layer 13 is not particularly limited, but is preferably, for example, 10 μm or more, and more preferably 20 μm or more, and is preferably 1000 μm or less, and more preferably 500 μm or less.

[0130] The type of adhesive constituting the adhesive layers 34a and 34b is not particularly limited, and any conventionally known adhesive can be used. For example, the adhesive can be an acrylic adhesive, a silicone adhesive, a urethane adhesive, a rubber adhesive, or the like, and among them, an acrylic adhesive is preferred because it is easy to achieve good adhesion and transparency.

[0131] The thickness of the adhesive layers 34a and 34b is not particularly limited as long as sufficient adhesiveness can be achieved, and is preferably, for example, 1 μm or more, and more preferably 3 μm or more. The thickness is also preferably 100 μm or less, and more preferably 30 μm or less.

[0132] The reflective layer 35 may be a reflective layer having a smooth surface (specular reflective layer) or a reflective layer that exhibits retroreflection. In the case of a specular reflective layer, it can be formed as a metal vapor deposition layer by, for example, depositing a metal on the surface of the transparent resin film 31e. Examples of the metal vapor deposition layer include an aluminum vapor deposition layer, a silver vapor deposition layer, a stainless steel vapor deposition layer, and a copper vapor deposition layer. In this case, the thickness of the reflective layer 35 can be a general thickness for a metal vapor deposition layer.

[0133] In the case of a reflective layer that has retroreflection, for example, a reflective surface having a large number of corner cubes (corner cube type, prism lens type), a reflective surface having a structure in which a large number of glass beads are arranged and covered with a transparent resin film with a space thereon (capsule lens type), a transparent resin sheet having a structure in which a large number of glass beads are enclosed (encapsulated lens type), a reflective surface having a large number of glass beads exposed (exposed lens type), etc. can be used. In this case, the thickness of the reflective layer 35 is not particularly limited, and may be, for example, 0.01 mm or more, particularly 0.1 mm or more. In addition, the thickness may be, for example, 1 mm or less, particularly 0.5 mm or less.

[0134] The ambient light-utilizing display 3 in this embodiment can be manufactured by a conventionally known method, and is not particularly limited.

[0135] When the external light-utilizing display 3 in this embodiment is used, for example, as a built-in station sign (a station sign installed on the platform at the same height as people's line of sight), even in a station where there is no lighting in the surrounding area, passengers on the train can see the built-in station sign at night by using the light from the train, particularly the light leaking through the doors.

[0136] The above-described embodiments are described for the purpose of facilitating understanding of the present invention, and are not described for the purpose of limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. EXAMPLES

[0137] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to these examples.

[0138] [Production Example 1] (Production of light diffusion control film having louver structure (1)) 1. Preparation of light diffusion control composition Polypropylene glycol, isophorone diisocyanate, and 2-hydroxyethyl methacrylate were reacted to obtain a polyether urethane methacrylate having a weight average molecular weight of 9,900. 60 parts by mass of o-phenylphenoxyethoxyethyl acrylate, 40 parts by mass of the above polyether urethane methacrylate, 8 parts by mass of 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photopolymerization initiator, 0.2 parts by mass (0.18% by mass) of a hindered amine compound (manufactured by BASF, product name "Tinuvin 292"), and 0.08 parts by mass (0.07% by mass) of a benzophenone compound (manufactured by BASF, product name "Tinuvin 384-2") as an ultraviolet absorbing agent were mixed together, and the mixture was heated and mixed at 80°C to obtain a light diffusion control composition.

[0139] The weight average molecular weight (Mw) mentioned above is a weight average molecular weight measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement) and converted into standard polystyrene. <Measurement conditions> Measuring device: Tosoh HLC-8320 GPC columns (passed in the following order): Tosoh Corporation TSK gel superH-H TSK gel superHM-H TSK gel superH2000 Measurement solvent: Tetrahydrofuran ·Measurement temperature: 40℃

[0140] 2. Formation of light diffusion control film The obtained light diffusion-controlling composition was applied to one side of a long polyethylene terephthalate film (thickness 50 μm; first PET film) as a process sheet to form a coating film, thereby obtaining a laminate consisting of the coating film and the process sheet.

[0141] The obtained laminate was then placed on a conveyor. At this time, the surface of the laminate on which the coating film was located was on the upper side, and the longitudinal direction of the process sheet was parallel to the flow direction of the conveyor. Then, an ultraviolet irradiation device (manufactured by iGraphics, product name "ECS-4011GX") having a linear high-pressure mercury lamp with a cold mirror for focusing was placed on the conveyor on which the laminate was placed. This device can irradiate ultraviolet light focused in a strip shape (almost linear shape) to a target. When the device was installed, the ultraviolet irradiation device was installed so that the longitudinal direction of the high-pressure mercury lamp and the flow direction of the conveyor were perpendicular to each other.

[0142] Furthermore, when viewed from the longitudinal direction of the high-pressure mercury lamp, the irradiation angle of the ultraviolet light irradiated from the high-pressure mercury lamp to the laminate was set to 10° with respect to the normal to the laminate surface. Note that the irradiation angle here refers to the acute angle between the normal to the laminate surface and the ultraviolet light, expressed as a plus sign, when the ultraviolet light is irradiated toward the downstream side of the conveyor flow, with respect to the position directly below the high-pressure mercury lamp on the laminate, and the acute angle between the normal to the laminate surface and the ultraviolet light, expressed as a minus sign, when the ultraviolet light is irradiated toward the upstream side of the conveyor flow.

[0143] Thereafter, the conveyor was operated to move the laminate at a speed of 1.0 m / min while applying a peak irradiance of 2.5 mW / cm2 to the coating surface. 2 , cumulative light intensity 40.0mJ / cm 2 The coating film in the laminate was cured by irradiating it with ultraviolet light under the above conditions (this curing is sometimes referred to as "primary curing" for convenience).

[0144] Next, a 38 μm-thick polyethylene terephthalate film (second PET film) was laminated on the surface of the laminate facing the coating film, and a peak illuminance of 190 mW / cm was applied to the coating film through the sheet. 2 , cumulative light intensity 180mJ / cm 2 The coating film in the laminate was cured by irradiating it with ultraviolet light (scattered light) under the above conditions (this curing is sometimes referred to as "secondary curing" for convenience). The peak irradiance and integrated light quantity mentioned above were measured by placing a UV METER (manufactured by Eye Graphics, product name "Eye UV Integrated Illuminance Meter UVPF-A1") equipped with a receiver at the position of the coating film.

[0145] Through the above primary curing and secondary curing, the above-mentioned coating film was cured to form a light diffusion control film having a thickness of 200 μm. This resulted in a laminate having a second PET film having a thickness of 38 μm, a light diffusion control film, and a first PET film (process sheet) having a thickness of 50 μm laminated in this order. The thickness of the light diffusion control film was measured using a constant pressure thickness measuring device (manufactured by Takara Seisakusho Co., Ltd., product name "TECLOCK PG-02J").

[0146] When the cross section of the formed light diffusion control film was observed using a microscope, it was confirmed that a louver structure was formed inside the light diffusion control film, in which multiple plate-shaped regions were arranged alternately in one direction along the film surface.

[0147] [Production Example 2] (Production of light diffusion control film having louver structure (2)) A light diffusion control composition was prepared in the same manner as in Production Example 1, except that the amount of the hindered amine compound was changed to 0.5 parts by mass (0.46% by mass). A light diffusion control film laminate was produced in the same manner as in Production Example 1 using the light diffusion control composition.

[0148] [Production Example 3] (Production of light diffusion control film having louver structure (3)) A light diffusion control composition was prepared in the same manner as in Production Example 1, except that the amount of the hindered amine compound was changed to 1 part by mass (0.92% by mass). A light diffusion control film laminate was produced in the same manner as in Production Example 1 using the light diffusion control composition.

[0149] [Production Example 4] (Production of light diffusion control film having louver structure (4)) A light diffusion control composition was prepared in the same manner as in Production Example 1, except that the amount of the hindered amine compound was changed to 2 parts by mass (1.82% by mass). A light diffusion control film laminate was produced in the same manner as in Production Example 1 using the light diffusion control composition.

[0150] [Production Example 5] (Production of light diffusion control film having louver structure (5)) A light diffusion control composition was prepared in the same manner as in Production Example 1, except that the hindered amine compound and the benzophenone compound were not added, and a light diffusion control film laminate was produced using the light diffusion control composition in the same manner as in Production Example 1.

[0151] [Production Example 6] (Production of light diffusion control film having louver structure (6)) A light diffusion control composition was prepared in the same manner as in Production Example 1, except that no hindered amine compound was added, and a light diffusion control film laminate was produced using the light diffusion control composition in the same manner as in Production Example 1.

[0152] Example 1 An acrylic adhesive layer (without UV absorber, thickness 25 μm) was laminated on the first PET film side of the light diffusion control film laminate (second PET film / light diffusion control film / first PET film) produced in Production Example 1.

[0153] Next, an acrylic pressure-sensitive adhesive layer (thickness 20 μm) containing an ultraviolet absorbing agent was laminated on one surface of a first polyvinyl chloride resin (PVC) film (containing an ultraviolet absorbing agent, thickness 80 μm).

[0154] An aluminum layer (nanometer-order thickness) was deposited as a reflective layer on one side of a second PVC film (no ultraviolet absorber, thickness 50 μm), and an acrylic adhesive layer (no ultraviolet absorber, thickness 25 μm) was laminated on the side of the PVC film opposite to the reflective layer.

[0155] Furthermore, an acrylic adhesive layer (thickness 20 μm) containing an ultraviolet absorbing agent was laminated on one surface of the fluororesin film (containing an ultraviolet absorbing agent, thickness 100 μm).

[0156] The above components were stacked to obtain a laminate as a pseudo-ambient light display consisting of, from the top, a fluorine-based resin film, an acrylic adhesive layer containing an ultraviolet absorber, a first PVC film, an acrylic adhesive layer containing an ultraviolet absorber, a second PET film, a light diffusion control film, the first PET film, an acrylic adhesive layer, a reflective layer, a second PVC film, and an acrylic adhesive layer (see Figure 4, but without the decorative layer).

[0157] Example 2 A laminate as a pseudo ambient light-utilizing display was produced in the same manner as in Example 1, except that the light diffusion control film obtained in Production Example 2 was used.

[0158] Example 3 A laminate was produced as a pseudo ambient light-utilizing display in the same manner as in Example 1, except that the light diffusion control film obtained in Production Example 3 was used.

[0159] Example 4 A laminate as a pseudo ambient light-utilizing display was produced in the same manner as in Example 1, except that the light diffusion control film obtained in Production Example 4 was used.

[0160] Comparative Example 1 A laminate as a pseudo ambient light-utilizing display was produced in the same manner as in Example 1, except that the light diffusion control film obtained in Production Example 5 was used.

[0161] Comparative Example 2 A laminate as a pseudo ambient light-utilizing display was produced in the same manner as in Example 1, except that the light diffusion control film obtained in Production Example 6 was used.

[0162] Comparative Example 3 The laminate of the light diffusion control film obtained in Production Example 6 (second PET film / light diffusion control film / first PET film) was used as Comparative Example 3.

[0163] [Test Example 1] (Measurement of light transmittance) The adhesive layer containing the ultraviolet (UV) absorbent used in the examples and comparative examples was attached to a glass plate, which was used as a sample. The light transmittance (%) of the sample was measured using an ultraviolet-visible-near infrared (UV-Vis-NIR) spectrophotometer (manufactured by Shimadzu Corporation, product name "UV-3600"). Based on the results, the light transmittance at wavelengths of 380 nm, 480 nm, and 580 nm is shown in Table 1.

[0164] The light transmittance (%) of the first PVC film used in the examples and comparative examples was measured in the same manner as above. The light transmittances at wavelengths of 380 nm, 480 nm, and 580 nm based on the results are shown in Table 1.

[0165] The light transmittance (%) of the fluororesin films used in the examples and comparative examples was measured in the same manner as above. The light transmittances at wavelengths of 380 nm, 480 nm, and 580 nm based on the results are shown in Table 1.

[0166] The laminates (four layers from the top) of the fluorine-based resin film, the adhesive layer containing the ultraviolet absorbing agent, the first PVC film, and the adhesive layer containing the ultraviolet absorbing agent produced in Examples 1 to 4 and Comparative Examples 1 to 2 were attached to a glass plate via the adhesive layer, and used as samples. The light transmittance (%) of the samples was measured in the same manner as above. The light transmittances at wavelengths of 380 nm, 480 nm, and 580 nm based on the results are shown in Table 1.

[0167] [Test Example 2] (Measurement of variable haze angle range) The haze value (%) of the light diffusion control film used in the examples and comparative examples was measured using a variable angle haze meter (manufactured by Toyo Seiki Seisakusho, product name "Haze Guard Plus, variable angle haze meter"). Specifically, a light beam was irradiated onto the surface of the second PET film side of the light diffusion control film laminate (second PET film / light diffusion control film / first PET film) while changing the incident angle with respect to the normal line within the range of -70° to 70° (within the range of ±70° from the normal line) along the longitudinal direction of the light diffusion control film, and the haze value (%) was measured for each incident angle. The details of the measurement conditions were as follows. Light source: C light source Measurement diameter: φ18mm Integrating sphere aperture diameter: φ25.4mm

[0168] Next, from the results of the above measurement, the range of incident angles where the haze value was 60% or more was identified from the measurement range of incident angles (-70° to 70°), and the difference between the two angles at the end points of the range was calculated, and this was defined as the angle range (variable haze angle range) that gave a haze value of 60% or more. The results are shown in Table 2.

[0169] [Test Example 3] (Measurement of Yxy and L*a*b*) The laminates obtained in the examples and comparative examples as pseudo ambient light display bodies were measured for lightness Y, chromaticity x, and chromaticity y defined by the CIE1931XYZ(Yxy) color system, and lightness L*, chromaticity a*, and chromaticity b* defined by the CIE1976L*a*b* color system using an ultraviolet-visible near-infrared (UV-Vis-NIR) spectrophotometer (Shimadzu Corporation, product name "UV-3600"). The results are shown in Table 2.

[0170] In addition, the laminates obtained in the examples and comparative examples as pseudo-ambient light display bodies were irradiated with ultraviolet light for 1000 hours in an atmosphere of 63±3°C (black panel temperature) and 50% RH using an ultraviolet fade meter (manufactured by Suga Test Instruments Co., Ltd., product name "U48") in accordance with JIS A1439:2016 (irradiance: 500±100 W / m 2) The lightness Y, chromaticity x, chromaticity y, lightness L*, chromaticity a*, and chromaticity b* of the laminate were then measured in the same manner as above. In addition, Δb*, which is the difference in chromaticity b* before and after the ultraviolet ray irradiation, was calculated. The results are shown in Table 3.

[0171] On the other hand, the laminates obtained in the examples and comparative examples as pseudo ambient light display bodies were irradiated with ultraviolet light for 1000 hours in an atmosphere of 63±3°C (black panel temperature) and 50% RH using a Sunshine Weather Meter (SWOM) (manufactured by Suga Test Instruments Co., Ltd., product name "S80") in accordance with JIS A1439:2016 (irradiance: 78.5 W / m 2 ) The lightness Y, chromaticity x, chromaticity y, lightness L*, chromaticity a*, and chromaticity b* of the laminate were then measured in the same manner as above. In addition, Δb*, which is the difference in chromaticity b* before and after the ultraviolet ray irradiation, was calculated. The results are shown in Table 4.

[0172] [Test Example 4] (Measurement of YI) The yellowness index YI of the laminates as pseudo ambient light display bodies obtained in the examples and comparative examples was measured using a spectrophotometer (manufactured by Nippon Denshoku Industries Co., Ltd., product name "SE6000") in accordance with JIS K7373: 2006. The results are shown in Table 2.

[0173] In addition, the laminates obtained in the examples and comparative examples as pseudo-external light display bodies were irradiated with ultraviolet light for 1000 hours using an ultraviolet fade meter (Fade) in the same manner as in Test Example 3. The yellowness index YI of the laminates after that was measured in the same manner as above. In addition, the yellowness index ΔYI, which is the difference in yellowness index YI before and after the ultraviolet light irradiation, was calculated. The results are shown in Table 3.

[0174] On the other hand, the laminates as the pseudo-external light display bodies obtained in the examples and comparative examples were irradiated with ultraviolet light for 1000 hours using a sunshine weather meter (SWOM) in the same manner as in Test Example 3. The yellowness index YI of the laminates after that was measured in the same manner as above. In addition, the yellowness index ΔYI, which is the difference between the yellowness index YI before and after the ultraviolet light irradiation, was calculated. The results are shown in Table 4.

[0175] [Test Example 5] (Evaluation of liquefaction inhibition) The laminates obtained in the examples and comparative examples as pseudo-ambient light display bodies were irradiated with ultraviolet light for 1000 hours using an ultraviolet fade meter in the same manner as in Test Example 3. The laminates were then disassembled to check the liquefaction of the light diffusion control film. The liquefaction inhibition was evaluated based on the following evaluation criteria. The results are shown in Table 3.

[0176] On the other hand, the laminates as the pseudo-ambient light display bodies obtained in the examples and comparative examples were irradiated with ultraviolet light for 1000 hours using a sunshine weather meter (SWOM) in the same manner as in Test Example 3. The laminates were then disassembled to check the liquefaction of the light diffusion control film. The liquefaction inhibition was evaluated based on the following evaluation criteria. The results are shown in Table 4.

[0177] <Evaluation criteria for liquefaction prevention> ◎: No liquefaction occurred at all. ◯: When the light diffusion control film was peeled off from the PET film, some stickiness was observed on the surface of the light diffusion control film. ×: The entire surface had liquefied.

[0178] [Table 1]

[0179] [Table 2]

[0180] [Table 3]

[0181] [Table 4]

[0182] As can be seen from Tables 3 and 4, in the laminates as pseudo ambient light-utilizing displays obtained in the Examples, liquefaction and yellowing of the light diffusion control film caused by long-term exposure to ultraviolet light was sufficiently suppressed. [Industrial Applicability]

[0183] The light diffusion control film and laminate according to the present invention can be suitably used, for example, as a window film for controlling the viewing angle, or as an external light-utilizing display device with improved visibility from a specific angle. [Explanation of symbols]

[0184] 1. Light diffusion control film 11A…Column structure 111...Columnar object with relatively high refractive index 112...Area with relatively low refractive index 11B…Louver structure 113... Plate-shaped region with relatively high refractive index 114...Area with relatively low refractive index 2. Window film 211...Hard coat layer 21a, 21b, 21c...Transparent resin film 22a, 22b...adhesive layer containing ultraviolet absorbing agent 20…Window glass 2 3. Display using natural light 31a, 31b, 31c, 31d, 31e...Transparent resin film 32a, 32b...adhesive layer containing ultraviolet absorbing agent 33…Decorative layer 34a, 34b...adhesive layer 35...Reflection layer 30...Base material (frame member)

Claims

1. A laminate used in an environment exposed to external light, A light diffusion control film having an internal structure including a plurality of regions having a relatively high refractive index within a region having a relatively low refractive index; an ultraviolet absorbing layer located on the external light incidence side of the light diffusion control film; Equipped with The light diffusion control film contains a hindered amine compound, the internal structure has at least one of a column structure in which a plurality of pillars having a relatively high refractive index stand in a film thickness direction in a region having a relatively low refractive index, and a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along the film surface, The ultraviolet absorbing layer has a light transmittance of 1% or less at a wavelength of 380 nm. A laminate comprising:

2. 2. The laminate according to claim 1, wherein the content of the hindered amine compound in the light diffusion control film is 0.01% by mass or more and 10% by mass or less.

3. 3. The laminate according to claim 1 or 2, characterized in that the light diffusion control film is obtained from a composition containing a high refractive index component, a low refractive index component having a refractive index lower than that of the high refractive index component, and a hindered amine compound.

4. The laminate according to any one of claims 1 to 3, characterized in that the light diffusion control film contains an ultraviolet absorbing agent.

5. The laminate according to any one of claims 1 to 4, which is a window film.

6. 6. The laminate according to claim 5, further comprising an ultraviolet absorbing layer on both sides of the light diffusion control film.

7. 5. The laminate according to claim 1, which is an external light-utilizing display.

8. A method for using a light diffusion control film in a laminate used in an environment exposed to external light, comprising: The light diffusion control film is The film has an internal structure having a plurality of regions with a relatively high refractive index within a region with a relatively low refractive index, Contains a hindered amine compound, the internal structure has at least one of a column structure in which a plurality of pillars having a relatively high refractive index stand in a film thickness direction in a region having a relatively low refractive index, and a louver structure in which a plurality of plate-like regions having different refractive indexes are alternately arranged in any one direction along the film surface, The laminate is provided with an ultraviolet absorbing layer located on the external light incidence side of the light diffusion control film and having a light transmittance of 1% or less at a wavelength of 380 nm. A method for using a light diffusion control film.

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