JP2012163715A - Light-diffusing film for led lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-diffusing film which achieves both erasure of an actual image of an LED light source and high light transmittance, and is also provided with rigidity.SOLUTION: The light-diffusing film for the LED lamp has two or more transparent base materials, and has particles with a weight average particle diameter of 10 μm or more and 20 μm or less together with a binder contained in a site other than the outer most layer.

Description

  The present invention relates to a light diffusing film for LED illumination that has been provided with rigidity while achieving both erasure of an actual image of an LED light source and high light transmittance.

  With the background of recent technological growth and energy consumption efficiency, LEDs have started to enter the lighting field. A point that differs greatly from incandescent light bulbs and fluorescent lamps that have been used up to now is that LEDs are point light sources. For this reason, when using LED as illumination, the light diffusion sheet of strong diffusion and high light transmittance is calculated | required so that the lamp image of a point light source may be lost (for example, refer patent document 1). However, in general, when the diffusion is increased, the light transmittance is greatly reduced. Therefore, it is difficult to achieve both the erasure of the lamp image of the LED light source and the high light transmittance.

  Here, as an example of the light diffusing sheet, for example, in a rear projection type transmission screen in which an image projected from a projector can be viewed from the opposite side of the screen, flat on both sides of the scattering layer. The transparent body is a flat glass or a polymer resin sheet, and the light scattering layer has a transparent binder and an average particle size of 1.0 μm to 10 .mu.m. What is a forward scattering light scattering layer containing spherical fine particles of 0 μm and having a relative refractive index n of 0.91 <n <1.09 (where n ≠ 1) with respect to the refractive index of the transparent binder. (For example, refer to Patent Document 2).

JP 2010-77179 A Japanese Patent No. 4129275

As described above, diffusion films for LED lighting have been developed in the direction of increasing diffusion so as to eliminate the lamp image of the point light source. However, in general, there is a trade-off relationship in which the high light transmittance decreases as the diffusion increases. On the other hand, when used for illumination, rigidity is required so as not to be bent by wind pressure or pressing to prevent falling. Therefore, when multiple particles are used and the particles are dispersed together with the binder in parts other than the outermost layer, the erasure of the lamp image of the point light source is improved, but the actual image of the LED light source itself is reflected and reflected. It became clear.
In view of the above problems, an object of the present invention is to provide a light diffusing film having rigidity while simultaneously erasing an actual image of an LED light source and high light transmittance.

It has been clarified that when the particles other than the outermost layer are filled in the light scattering film, the actual image of the LED light source is reflected. Therefore, it has been necessary to diffuse excessively at the expense of some transmittance.
In view of the above situation, as a result of intensive studies by the present inventors, particles having at least two transparent substrates and having a weight average particle diameter of 10 μm or more and 20 μm or less together with a binder in a portion other than the outermost layer It has been found that the inclusion of contains both the elimination of the actual image of the LED light source and high light transmittance, and the rigidity is improved.
That is, the present invention is as follows.

<1> having two or more transparent substrates,
A light diffusing film for LED lighting containing particles having a weight average particle diameter of 10 μm or more and 20 μm or less together with a binder in a portion other than the outermost layer.

<2> The light diffusing film for LED illumination according to <1>, wherein at least one of the transparent substrates is a biaxially stretched PET film.

<3> The light diffusing film for LED illumination according to <1> or <2>, wherein the particles are contained between the two transparent substrates facing each other together with the binder.

<4> The above <1> to <1> provided with at least one of a hard coat layer having a thickness of 2 μm to 10 μm and a layer having a refractive index of 1.3 to 1.6 and a thickness of 10 nm to 200 nm on the outermost surface. 3> The light-diffusion film for LED illumination of any one of 3>.

<5> LED illumination light diffusion film according to any one of the total application amount is said is ^{10g / m 2 ~100g / m 2} <1> ~ <4> of the particles.

  According to the present invention, even when particles other than the outermost layer are filled, the actual image of the LED light source is erased, and a high light transmittance and high rigidity light diffusion film for LED illumination is provided. The

It is a schematic sectional drawing which shows an example of the light-diffusion film for LED lighting of this invention. It is a schematic sectional drawing which shows another example of the light-diffusion film for LED lighting of this invention. It is a schematic sectional drawing which shows another example of the light-diffusion film for LED lighting of this invention. It is a schematic sectional drawing which shows another example of the light-diffusion film for LED lighting of this invention. It is a schematic sectional drawing which shows another example of the light-diffusion film for LED lighting of this invention. It is a schematic sectional drawing which shows another example of the light-diffusion film for LED lighting of this invention. 10 is a cross-sectional view illustrating an outline of a layer configuration of Comparative Example 3. FIG.

  The light diffusing film for LED illumination of the present invention (hereinafter sometimes referred to simply as “light diffusing film”) has two or more transparent base materials, and has a weight average particle diameter together with a binder in a portion other than the outermost layer. Contains particles of 10 μm or more and 20 μm or less.

When there is only one substrate as in the past, particles are applied to the substrate surface, so that the incident light is sufficiently diffused by the particles, and the actual image of the LED light source is observed through the light diffusion layer film. It wasn't. However, when two or more transparent substrates are used to increase the rigidity of the light diffusion film and particles are contained together with the binder in a portion other than the outermost layer, it has become clear that the actual image of the LED light source is reflected. .
Therefore, even when the particles other than the outermost layer are contained together with the binder, a method for erasing the actual image of the LED light source has been studied. The weight average particle diameter of the added particles is 10 μm or more and 20 μm. The following was found to be effective. The reason for this is not clear, but by setting the particle diameter to 10 μm or more, the scattering property change for each wavelength in each particle is reduced, and the phenomenon that only the light in the local wavelength region is scattered is suppressed, It is presumed that both real image erasure and light transmittance of the LED light source can be achieved. Further, it is presumed that by setting the weight average particle diameter to 20 μm or less, the coating suitability is improved and a uniform coated surface can be realized.

  In addition, the said particle | grain should just be contained with the binder in site | parts other than outermost layer. Below, the example of the layer structure of the light-diffusion film of this invention is demonstrated, referring a figure. Moreover, the light-diffusion film of this invention may have other layers, such as an adhesive layer, an easily bonding layer, and a surface coating layer, as needed.

  In FIGS. 1-6, an example is shown as sectional drawing about the layer structure of the light-diffusion film for LED illumination of this invention.

  The light diffusion film 1 shown in FIG. 1 has two transparent substrates 10 and 12, and an adhesive layer 14 and a diffusion layer 16 are provided between the two transparent substrates 10 and 12. Between the transparent substrates 10 and 12, particles 22 having a weight average particle diameter of 10 μm or more and 20 μm or less are contained together with a binder. In FIG. 1, the particles 22 are contained in the diffusion layer 16. However, part of the particles 22 may be configured to be included in the adhesive layer 14. When a part of the particles 22 is included in the adhesive layer, peeling between the layers can be suppressed. The diffusion layer 16 and the adhesive layer 14 contain a binder.

In FIG. 1, surface coating layers 18 and 20 are further provided on the outer surfaces of the transparent base materials 10 and 12. However, the installation of the surface coating layers 18 and 20 is arbitrary, and only one of the surface coating layers 18 and 20 may be installed.
Examples of the surface coating layers 18 and 20 include a hard coat layer and a refractive index adjusting layer that relaxes the difference in refractive index between air and a diffusion film.

  The light diffusion film 2 for LED illumination shown in FIG. 2 has two transparent substrates 10 and 12, and a diffusion layer 16, an adhesive layer 14, a diffusion layer 17, and a transparent substrate 12 are provided in this order from the transparent substrate 10 side. ing. Further, surface coating layers 18 and 20 are provided on the outer surfaces of the transparent substrates 10 and 12. Installation of the surface coating layers 18 and 20 is arbitrary.

  The particles 22 having a weight average particle diameter of 10 μm or more and 20 μm or less are contained in the diffusion layers 16 and 17. However, part of the particles 22 may be configured to be included in the adhesive layer 14. The diffusion layers 16 and 17 and the adhesive layer 14 contain a binder.

  The light diffusion film 3 for LED illumination shown in FIG. 3 has two transparent substrates 10 and 12, and a diffusion layer 16 containing particles 22 is sandwiched between the two transparent substrates 10 and 12. The diffusion layer 16 also has a bonding function. Further, surface coating layers 18 and 20 are provided on the outer surfaces of the transparent substrates 10 and 12. Installation of the surface coating layers 18 and 20 is arbitrary.

The light diffusing film 4 shown in FIG. 4 has two transparent substrates 10 and 12, and an adhesive layer 14 is provided between the two transparent substrates 10 and 12. The transparent substrate 12 is bonded.
A diffusion layer 16 is provided on the surface of the transparent substrate 10 opposite to the adhesive layer 14, and particles 22 are contained in the diffusion layer 16. A surface coating layer 18 is provided on the outer surface of the diffusion layer 16. In addition, the surface coating layer 18 is essential in the light diffusion film 4 shown in FIG. 4 so that the diffusion layer 16 does not become the outermost layer. Further, a part of the particles 22 may be configured to be included in the surface coating layer 18. However, the particles 22 are not exposed from the outermost surface of the surface coating layer 18.
In the light diffusion film 4 shown in FIG. 4, the surface coating layer 20 is provided on the outer surface of the transparent substrate 12, but the installation of the surface coating layer 20 is arbitrary.

  As shown in FIGS. 1 to 3, when the particles 22 are contained between the two transparent substrates 10 and 12 facing each other, the smoothness of the outer surfaces of the transparent substrates 10 and 12 is maintained. Therefore, it is easy to install the surface coating layers 18 and 20 on the outer surfaces of the transparent substrates 10 and 12, and it is possible to provide a new function by providing a functional layer on the outermost surface of the light diffusion film for LED illumination. Become.

  1-4 demonstrated the light-diffusion film for LED illumination which uses two transparent substrates, However, The transparent substrate should just be 2 or more, and may be 3 or more. Moreover, the light-diffusion film for LED illumination of this invention should just contain the particle | grains 22 which have a weight average particle diameter of 10 micrometers or more and 20 micrometers or less, and also contains the particle | grains which have the weight average particle diameter out of the said range. Good. Examples of such other particles include fine particles described later.

A light diffusion film 5 shown in FIG. 5 is a light diffusion film for LED illumination using three transparent substrates. The transparent substrate 10, the adhesive layer 14A, the transparent substrate 11, the adhesive layer 14B, the diffusion layer 16, and the transparent substrate 12 are laminated in this order from the first transparent substrate 10 side. Further, surface coating layers 18 and 20 are provided on the outer surfaces of the transparent substrates 10 and 12. Installation of the surface coating layers 18 and 20 is arbitrary.
The particles 22 having a weight average particle diameter of 10 μm or more and 20 μm or less are contained in the diffusion layer 16. However, a part of the particles 22 may be configured to be included in the adhesive layer 14B.

  In the light diffusion film 5 shown in FIG. 5, the laminated portion of the transparent substrate 11, the adhesive layer 14B, the diffusion layer 16, and the transparent substrate 12 conforms to the configuration of FIG. You may change to any structure of 4.

The light diffusion film 6 shown in FIG. 6 is also a light diffusion film for LED illumination using three transparent substrates. The transparent substrate 10, the adhesive layer 14A, the diffusion layer 16A, the transparent substrate 11, the adhesive layer 14B, the diffusion layer 16B, and the transparent substrate 12 are laminated in order from the first transparent substrate 10 side. Further, surface coating layers 18 and 20 are provided on the outer surfaces of the transparent substrates 10 and 12. Installation of the surface coating layers 18 and 20 is arbitrary.
The particles 22 having a weight average particle diameter of 10 μm or more and 20 μm or less are contained in the diffusion layers 16A and 16B. However, a part of the particles 22 may be configured to be included in the adhesive layers 14A and 14B.

  In the light diffusion film 6 shown in FIG. 6, the transparent substrate 10, the adhesive layer 14 </ b> A, the diffusion layer 16 </ b> A, and the laminated portion of the transparent substrate 11, and the transparent substrate 11, the adhesive layer 14 </ b> B, the diffusion layer 16 </ b> B, and the transparent substrate 12. The layered portion is in conformity with the configuration of FIG. 1, but the layered portion may be changed to any of the configurations of FIGS.

  Below, the member which comprises the light-diffusion film for LED illumination of this invention is demonstrated in detail.

<Transparent substrate>
As the transparent substrate, plastics, glass and the like usually used as a transparent substrate can be appropriately selected and used according to the purpose.

  Suitable examples of the plastic include polyester, polyolefin, acrylic, and polycarbonate. Examples of the polyester include polyethylene terephthalate (PET, refractive index 1.67), polyethylene naphthalate (PEN), and the like. Examples of other plastics include polyamide, polyether, polystyrene, polyesteramide, polycarbonate, polyphenylene sulfide, polyether ester, polyvinyl chloride, polyacrylic acid ester, and polymethacrylic acid ester. Among these, a polyester resin is preferable.

  Polyethylene terephthalate (PET) is oriented and crystallized by biaxial stretching, and is improved in strength and heat resistance.

Although there is no restriction | limiting in particular in a draw ratio, It is preferable that it is what was extended | stretched 1.5 to 7 times in the vertical and horizontal directions, respectively, More preferably, it is about 2 to 5 times. When the draw ratio is within the above range, sufficient mechanical strength and uniform thickness can be obtained.
These PET film production methods and conditions can be selected from known methods and conditions as appropriate.

  In addition, it is preferable to provide the other transparent substrate which is not a biaxially stretched PET film on the side close to the lighting fixture. As another transparent substrate used on the side close to the lighting fixture, it is preferable to use a material having a refractive index lower than that of polyethylene terephthalate (PET). For example, polycarbonate (refractive index 1.58), polymethyl methacrylate (refractive index 1). It is preferable to apply an acrylic resin such as .5).

  The thickness of the transparent substrate is not particularly limited as long as it is in a range usually employed as the transparent substrate, and can be appropriately selected according to the purpose. For example, 0.02 mm to 4.0 mm is preferable. 1 mm to 4 mm is more preferable, and 0.3 mm to 4 mm is still more preferable.

  The surface of the transparent substrate may be subjected to corona discharge treatment in order to improve adhesion with the diffusion layers 16 and 17 and the surface coating layers 18 and 20.

<Diffusion layer>
In the light scattering film of the present invention, particles other than the outermost layer contain particles having a weight average particle diameter of 10 μm or more and 20 μm or less together with the binder. A layer mainly containing these particles together with a binder will be described as a diffusion layer.

(particle)
In the light-scattering film of this invention, particle | grains are contained in site | parts other than the outermost layer with a binder. These particles have a weight average particle diameter of 10 μm or more and 20 μm or less, preferably 10 μm to 17 μm, and more preferably 12 μm to 17 μm. In addition, when using other particle | grains together, the particle | grains which have a weight average particle diameter other than the said range may be sufficient.

The weight average particle diameter of the particles is measured with a Coulter MULTISIZER (manufactured by BECKMAN COULTER) in a particle dispersion. When particle dispersion is impossible, the weight average particle diameter can be calculated by specifying each particle size / material from an image such as SEM of the diffusion film.
The “weight average particle diameter” of the particles in the present invention means a particle diameter defined as follows. When the particle diameter of each particle is di and the number of particles in each particle diameter is ni, the weight average particle diameter is represented by Σnidi ⁴ / Σnidi ³ .

  The refractive index of the particles is preferably in the range of 1.4 to 2.6, more preferably in the range of 1.4 to 2.1, and in the range of 1.4 to 1.7. More preferably it is.

  The measuring method of the refractive index of a particle group is demonstrated in the below-mentioned Example.

  The absolute value ΔN of the difference between the refractive index of the particles and the refractive index of the binder described later is preferably 0.01 to 0.3, and preferably 0.01 to 0.26 from the viewpoint of light diffusion. Is more preferable, and it is still more preferable that it is 0.01-0.2.

The material of the particles is not particularly limited and can be appropriately selected according to the purpose. For example, organic particles such as polymethyl methacrylate resin particles, melamine resin particles, polystyrene resin particles, and silicone resin particles are preferable. It is done. These may be used individually by 1 type and may be used in combination of 2 or more type.
The organic particles preferably have a crosslinked structure. Further, the organic particles may be coated on the surface, and for example, particles that are coated with silica or the like and the surface of which is hydrophilized or hydrophobized depending on the type of coating liquid are preferably used.

In the light diffusion film of the present invention, the total application amount of the particles ^{is 10g / m 2 ~100g / m 2} , is preferably ^{10g / m 2 ~90g / m 2} , 10g / m 2 ~80g / more preferably m ^2. When the total applied amount is 10 g / m ² or more, the actual image of the LED light source is effectively erased, and when it is 100 g / m ² or less, the coating suitability is excellent.

  The total amount of the particles added is preferably 10 parts by mass to 130 parts by mass with respect to 100 parts by mass of the following binder. When the added amount of the particles is within the above range, the dispersibility of the particles in the binder becomes good, and the function as a light diffusing agent is sufficiently achieved. More preferably, the addition amount of the particles is 10 parts by mass to 120 parts by mass, and more preferably 10 parts by mass to 115 parts by mass with respect to 100 parts by mass of the binder.

(Binder)
In the present invention, the binder refers to all solids (including ultrafine particles described later) excluding the particles to which the particles are added together. Specifically, it contains a resin, ultrafine particles, a crosslinking agent, other additives, and the like.
The refractive index of the binder is preferably 1.4 or more and 1.7 or less, and more preferably 1.4 or more and 1.6 or less.

-Resin-
As the resin contained as the binder, for example, when water is used as the dispersion medium of the diffusion layer coating liquid, it is desirable to use at least one resin selected from a water-soluble polymer and a water-dispersible polymer. Preferred examples of the resin include a homopolymer or a copolymer.

  Examples of the homopolymer or copolymer include (meth) acrylic resin, vinyl acetate resin, ethylene-vinyl acetate copolymer resin, vinyl chloride resin, vinyl chloride-vinylidene chloride copolymer resin, butyral resin, silicone resin, Examples include polyester resins, vinylidene fluoride resins, nitrocellulose resins, styrene resins, styrene-acrylonitrile copolymer resins, polyurethane resins, polyethylene, polypropylene, chlorinated polyethylene, and rosin derivatives.

The water-soluble and / or water-dispersible polymer is not particularly limited and can be appropriately selected according to the purpose.
Examples include water-soluble or water-dispersible polymers such as polyvinyl alcohol, methyl cellulose, gelatin, polyester resin, polyurethane resin, acrylic resin, amino resin, epoxy resin, and styrene butadiene copolymer. Resin-based, polyester resin-based, and polyurethane resin-based water-dispersed polymers are preferable, and polyurethane-resin-based water-dispersed polymers are more preferable. These may be used alone or in combination of two or more.

  It is also preferable to use a polymer that can react with the cross-linking agent. For example, a polymer having a hydroxyl group, an amino group, a carboxyl group, or the like can be used. Furthermore, the water-dispersible polymer preferably contains a substituent such as a sulfonic acid group, a hydroxyl group, a carboxylic acid group, an amino group, an amide group, and an ether group. These water-dispersible polymers may be used alone or in combination.

  In addition, when serving also as an adhesive layer, a resin described in the following adhesive layer may be used as the resin for the diffusion layer.

  The diffusion layer further includes scratch resistance during handling, solvent resistance against a solvent for wiping off dirt and dirt on the surface, and a transparent substrate for punching the light diffusion film for LED lighting into a predetermined form It is preferable to add a cross-linking agent for hardening in order to impart the adhesiveness.

-Crosslinking agent-
The diffusion layer further includes scratch resistance during handling, solvent resistance against a solvent for wiping off dirt and dirt on the surface, and a transparent substrate for punching the light diffusion film for LED lighting into a predetermined form It is preferable to add a cross-linking agent for hardening in order to impart the adhesiveness.

As said crosslinking agent, a carbodiimide compound and an isocyanate compound are preferable, and a carbodiimide compound is more preferable.
The carbodiimide compound used in the present invention has a carbodiimide group in the molecule and forms a chemical structure such as a carbamoylamide bond by reaction with a carboxyl group of a polyester resin or an isourea bond by reaction with a hydroxyl group of a polyester resin. To do. The chemical structure also includes a guanidine structure that is generated when reacted with an amino group.
Nisshinbo's Carbodilite E series (emulsion type), V series (aqueous type) and the like can be used as general commercial products.

As the isocyanate compound, at least one of an aliphatic isocyanate compound having at least 2, preferably 3 or more functional groups in the molecule, a cyclic aliphatic isocyanate compound, and an aromatic polyfunctional isocyanate compound is used. . As for the isocyanate compound, these crosslinking agents described in “Polyurethane Resin Handbook” (edited by Keiji Iwata, published by Nikkan Kogyo Shimbun, 1987) may be used alone or in admixture of two or more.

-Ultrafine particles-
Furthermore, the diffusion layer may contain other particles such as ultrafine particles made of inorganic particles. By containing the ultrafine particles, the suitability of the coating solution for forming the diffusion layer is improved, and the refractive index of the binder can be controlled.
Examples of the ultrafine particles include Ca, Si, Al, Ti, Zr, Ta, In, Nd, Sn, Sb, Zn, La, W, Ce, Nb, V, Sm, Y, and other oxides or composite oxides, Examples thereof include particles containing sulfide as a main component. Here, the main component refers to a component having the largest content (% by mass) among the components constituting the particles. For example, preferred specific examples include silica, calcium carbonate, alumina, zirconia, titanium oxide, antimony oxide and the like. These can be appropriately selected according to the purpose and dispersed and contained in the diffusion layer.
The particle diameter of the ultrafine particles is preferably in the range of 0.005 μm to 0.15 μm, and more preferably in the range of 0.005 μm to 0.1 μm.

  There is no restriction | limiting in particular in the addition amount in the said diffusion layer of the said ultrafine particle, Although it can select suitably according to a condition, For example, 1-20 mass% is preferable.

-Solvent-
There is no restriction | limiting in particular as a solvent used for the said spreading | diffusion layer coating liquid, It can select and use suitably from what is normally used, such as water and an organic solvent.
Examples of the organic solvent include ketones, ethers, alcohols, esters, polyhydric alcohol derivatives, carboxylic acids, and the like.

  The diffusion layer is formed by applying the diffusion layer coating liquid on the adhesive layer and then drying. The diffusion layer may be provided with only one layer or two or more layers.

  The method for applying the diffusion layer coating liquid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, by a commonly used coating means such as a spin coater, roll coater, bar coater, curtain coater, etc. It can be carried out.

  There is no restriction | limiting in particular as the drying method of the said spreading | diffusion layer coating liquid, According to the kind of solvent to be used, the method normally used can be selected suitably. For example, when water is used as the solvent, the drying temperature is preferably 90 ° C. to 140 ° C., more preferably 100 ° C. to 140 ° C., because it can be performed in a short time and without damaging the material. When the drying temperature is within the above range, drying does not require a long time and damage to the material is suppressed. The drying time is preferably, for example, 10 seconds to 5 minutes, and more preferably 1 minute to 3 minutes.

(Physical property values, etc.)
The thickness of the diffusion layer (when the particles are contained across two or more layers, the total thickness of the plurality of layers) is 1 μm to 20 μm from the viewpoint of achieving the effect of light scattering / efficiency. preferable.

  The average refractive index N3 of the diffusion layer is preferably not more than the refractive index N1 of the transparent substrate. Here, the average refractive index N3 is calculated by ΣNi * Vi, where Ni is the refractive index of each binder (solid component other than particles) and Vi is the volume fraction of the solid component contained in each binder. Value.

  Specifically, the refractive index N3 of the diffusion layer is preferably 1.5 to 1.67, and more preferably 1.5 to 1.6.

  Further, the difference between the refractive index N1 of the transparent substrate and the refractive index N3 of the diffusion layer is 0 to 0.1 from the viewpoint of improving light utilization efficiency by suppressing reflection at the interface between the transparent substrate and the diffusion layer. It is preferable.

<Other layers>
(Adhesive layer)
As described above, the diffusion layer may be a layer having an adhesion function, or an adhesive layer may be provided as a separate layer from the diffusion layer. When the adhesive layer is provided, it can be constituted using the following components.
There are no particular restrictions on the adhesive layer, such as acrylic, urethane, epoxy, silicone, etc., and commonly used substances can be appropriately selected and used according to the purpose. Specifically, as a laminate-based commercial product, for example, there is a two-component dry laminate material that can be used by adding an LCR-901 isocyanate-based curing agent to a LIS805 urethane-based main agent manufactured by Toyo Ink. can give. Furthermore, as the laminate, materials suitable for the extrusion method and the hot melt method can be used as appropriate.

The refractive index N2 of the adhesive layer is preferably 1.5 to 1.67.
The thickness of the adhesive layer is preferably 1 μm to 50 μm, and more preferably 1 μm to 20 μm, from the viewpoint of securely bonding without impairing light transmittance.

(Easily adhesive layer)
An easy adhesion layer may be provided on the surface of the transparent substrate. By providing the easy adhesion layer, peeling from the transparent substrate can be suppressed. As an easily bonding layer, the thing as described in Paragraph [0016]-[0027] of Unexamined-Japanese-Patent No. 2009-199001 is applicable, for example.

  The easy-adhesion layer is usually formed by applying a coating liquid comprising a binder, a curing agent, and a surfactant to one surface of the polyester support. You may add slipping agents, such as organic or inorganic microparticles | fine-particles, wax, to an easily bonding layer as needed.

  The binder used in the easy-adhesion layer is not particularly limited as long as it can improve the adhesion to the polyester support, but from the viewpoint of easy adhesion, one or more of polyester resin, polyurethane resin, acrylic resin, styrene butadiene resin Is preferably used. A water-soluble or water-dispersible binder is particularly preferable from the viewpoint of environmental load.

  In order to adjust the refractive index of the easy adhesion layer, metal oxide fine particles may be added to the easy adhesion layer. As the metal oxide fine particles, high refractive index metal oxides such as tin oxide, zirconium oxide, zinc oxide, titanium oxide, cerium oxide and niobium oxide are preferable. The particle diameter of the metal oxide fine particles is preferably in the range of 1 to 50 nm, particularly preferably in the range of 2 to 40 nm. The addition amount of the metal oxide in the easy-adhesion layer is preferably added in the range of 10 to 90 parts by mass, particularly 30 to 80 parts by mass in order to obtain the target refractive index. It is preferable to add in a range.

  The refractive index of the easy adhesion layer is preferably in the range of 1.56 to 1.64 for the purpose of reducing the interference color due to the reflection of the laminated film. If the refractive index is smaller than 1.56 or larger than 1.64, the effect of reducing the interference color is reduced.

  The formation method of an easily bonding layer is not specifically limited, A well-known coating method can be suitably selected according to the objective. For example, a spin coater, a roll coater, a bar coater, a curtain coater and the like can be mentioned. In any of the methods, a solution containing a material for forming an easy-adhesion layer is applied to a desired surface and then dried to form a layer. Here, the drying method is not particularly limited, and a commonly used method can be appropriately selected.

  The thickness of the easy adhesion layer is preferably 0.01 μm to 2 μm, and more preferably 0.01 μm to 1 μm. In addition, before forming the easy adhesion layer on the transparent substrate, corona discharge treatment, glow discharge treatment, atmospheric pressure plasma treatment, UV-ozone treatment, flame treatment, etc. Adhesion can be improved.

(Outermost layer)
As described above, the light scattering film of the present invention may be formed as an outermost surface layer by forming a surface coating layer on the outer surface of the transparent substrate. Examples of the surface coating layer include a hard coat layer and a refractive index adjustment layer.

-Hard coat layer-
The hard coat layer is a layer provided for improving scratch resistance. The thickness of the hard coat layer is preferably 1 μm to 20 μm, and more preferably 1 μm to 10 μm.

  The hard coat layer is composed of polyfunctional acrylic monomers that can be cured by irradiating ultraviolet rays, electron beams, etc., materials containing oligomers, and moisture heat curing using hydrolysis of alkoxysilane and dehydration condensation of silanol generated there. Type silica-based hard coat. Examples of the coating liquid formulation for forming the latter silica-based hard coat include aqueous solutions (aqueous coating compositions) containing the components described below.

[Organic silicon compound]
The organosilicon compound that can be used in the present invention is preferably an organosilicon compound represented by the general formula (1).
R ¹ R ² _n Si (OR ³ ) _3-n General Formula (1)
(Here, R ¹ represents an organic group having 1 to 15 carbon atoms not containing an amino group, R ² represents a methyl or ethyl group, R ³ represents an alkyl group having 1 to ³ carbon atoms, and n is 0. Or represents an integer of 1.)

Examples of the organic group having 1 to 15 carbon atoms that does not include the amino group represented by R ¹ include a substituted or unsubstituted alkyl group having 15 or less carbon atoms, a substituted or unsubstituted alkenyl group, Unsubstituted aryl groups are included. Examples of the substituent include halogen (fluorine, chlorine, bromine, etc.), hydroxyl group, mercapto group, carboxyl group, epoxy group, alkyl group (methyl, ethyl, i-propyl, propyl, t-butyl etc.), aryl group ( Phenyl, naphthyl, etc.), aromatic heterocyclic groups (furyl, pyrazolyl, pyridyl, etc.), alkoxy groups (methoxy, ethoxy, i-propoxy, hexyloxy, etc.), aryloxy (phenoxy, etc.), alkylthio groups (methylthio, ethylthio, etc.) ), Arylthio groups (such as phenylthio), alkenyl groups (such as vinyl and 1-propenyl), acyloxy groups (such as acetoxy, acryloyloxy, methacryloyloxy), alkoxycarbonyl groups (such as methoxycarbonyl and ethoxycarbonyl), aryloxycarbonyl groups ( Phenoxyca Boniru, etc.) are included.

  Although it will not specifically limit if it is a compound represented by General formula (1), As a preferable compound, 3-glycidoxypropyl trimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, vinyltrimethoxy Silane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-ureidopropyltrimethoxysilane, propyltrimethoxysilane, phenyltrimethoxysilane, 3-glycid Xylpropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, vinyltriethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltriethoxysilane, 3-chloro Ropropyltriethoxysilane, 3-ureidopropyltriethoxysilane, propyltriethoxysilane, phenyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, vinyl Methyldimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropylmethyldimethoxysilane, chloropropylmethyldimethoxysilane, propylmethyldimethoxysilane, phenylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2 -(3,4-epoxycyclohexyl) ethylmethyldiethoxysilane, vinylmethyldiethoxysilane, 3-methacryloxypropylmethyldiethoxysila , 3-acryloxypropylmethyldiethoxysilane, chloropropylmethyldiethoxysilane, propylmethyldiethoxysilane, phenylmethyldiethoxysilane, 3-trimethoxysilylpropyl-2- [2- (methoxyethoxy) ethoxy] ethylurethane 3-triethoxysilylpropyl-2- [2- (methoxyethoxy) ethoxy] ethylurethane, 3-trimethoxysilylpropyl-2- [2- (methoxypropoxy) propoxy] propylurethane, 3-triethoxysilylpropyl- 2- [2- (methoxypropoxy) propoxy] propylurethane is preferable, and trialkoxysilane of n = 0 is particularly preferable, 3-glycidoxypropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 2- ( 3, 4 -Epoxycyclohexyl) ethyltrimethoxysilane, 3-ureidopropyltriethoxysilane, 3-trimethoxysilylpropyl-2- [2- (methoxyethoxy) ethoxy] ethylurethane, 3-trimethoxysilylpropyl-2- [2- (Methoxypropoxy) propoxy] propyl urethane.

  The organosilicon compound represented by the general formula (1) has an organic group that does not contain an amino group, so as to improve compatibility with the polymer to be mixed and promote adhesion at the inorganic-organic interface. Since it is used, it is preferable that the organic group has a hetero atom such as oxygen, nitrogen, or sulfur. In particular, the organic group preferably has an epoxy group, an amide group, a urethane group, a urea group, an ester group, a hydroxyl group, a carboxyl group, or the like. Among these, an organosilicon compound containing an epoxy group is particularly preferable because it has an effect of increasing the stability of silanol in acidic water. When it has an amino group, when it mixes with a tetraalkoxysilane and hydrolyzes, since the dehydration condensation between the produced | generated silanols is accelerated | stimulated, there exists a problem that a coating liquid becomes unstable. Further, the molecular chain length of the organic group is preferably 3 to 15 carbon atoms, and particularly preferably 5 to 13 carbon atoms. When the carbon number is 2 or less, the effect of improving compatibility and adhesion with the polymer to be mixed is small. When the number of carbon atoms is 16 or more, the flexibility increases and the hardness of the film decreases.

[Tetraalkoxysilane]
The tetraalkoxysilane that can be used in the present invention is preferably an alkoxysilane having 1 to 4 carbon atoms. Tetramethoxysilane and tetraethoxysilane are particularly preferable. When the number of carbon atoms is 5 or more, the hydrolysis rate when added to acidic water is slow, and the dissolution time until a uniform aqueous solution is obtained becomes long.
Tetraalkoxysilane is used to increase the crosslink density and to increase the film hardness. The proportion of tetraalkoxysilane in the silane compound is preferably 20 to 95 mol%, particularly preferably 40 to 90 mol%. When the mixing ratio is less than 20 mol%, the crosslinking density is lowered and sufficient film hardness cannot be obtained. On the other hand, when the mixing ratio exceeds 90 mol%, the compatibility and adhesion with the polymer to be mixed are lowered, and the film becomes brittle.

[Acid water with pH 2-6]
The acidic water having a pH of 2 to 6 used in the present invention can be obtained by dissolving a normal organic acid or inorganic acid in water. The type of acid is not particularly limited, but organic acids such as acetic acid, propionic acid, formic acid, fumaric acid, maleic acid, oxalic acid, malonic acid, succinic acid, citric acid, malic acid, ascorbic acid, hydrochloric acid, nitric acid, sulfuric acid Inorganic acids such as phosphoric acid and boric acid can be used, but acetic acid is preferred from the viewpoint of handleability.
The pH is preferably in the range of 2-6 at room temperature, particularly preferably in the range of 3-5. When the pH is 1 or less or 7 or more, the condensation of silanol in the silane compound aqueous solution proceeds and gelation tends to occur.
60-2000 mass parts of water is preferable with respect to 100 mass parts of silane compounds, and, as for the mixing ratio of a silane compound and water, 100 mass parts-1500 mass parts are more preferable. 150 to 1200 parts by mass is particularly preferable. If the amount of water is less than 60 parts by mass, gelation by dehydration condensation of the produced silanol tends to proceed. When the amount of water is 2000 parts by mass or less, the concentration of the silane compound in the coating solution is prevented from becoming too low, the coating amount for obtaining a sufficient coating film thickness can be moderately suppressed, and uneven coating occurs. , Increase in drying load is suppressed.

[Curing aid]
Curing aids that can be used in the present invention are used to promote the formation of siloxane bonds by dehydration condensation of silanols.
Curing aids that can be used include inorganic acids such as boric acid, phosphoric acid, hydrochloric acid, nitric acid, sulfuric acid, organic acids such as acetic acid, formic acid, oxalic acid, citric acid, malic acid, ascorbic acid, aluminum acetate, oxalic acid Organic acid salts such as aluminum, zinc acetate, zinc oxalate, magnesium acetate, magnesium oxalate, zirconium acetate, zirconium oxalate, aluminum chloride, aluminum sulfate, aluminum nitrate, zinc chloride, zinc sulfate, zinc nitrate, magnesium chloride, sulfuric acid Inorganic acid salts such as magnesium, magnesium nitrate, zirconium chloride, zirconium sulfate and zirconium nitrate, metal alkoxides such as aluminum alkoxide, titanium alkoxide and zirconium alkoxide, aluminum acetylacetonate, aluminum ethylacetoacetate, titanium acetylacetonate , And metal complexes such as titanium ethylacetoacetate and the like.
Among these, compounds containing boron, phosphorus, and aluminum elements such as boric acid, phosphoric acid, aluminum alkoxide, and aluminum acetylacetonate are particularly preferable from the viewpoints of water solubility and stability in water.

[Colloidal silica]
The aqueous coating composition according to the present invention may contain an aqueous dispersion of colloidal silica having an average particle diameter of 50 nm or less and a pH of 2 to 7 for the purpose of improving film hardness. The average particle diameter is preferably in the range of 4 to 40 nm, particularly preferably in the range of 6 to 30 nm. When the average particle diameter of colloidal silica is 50 nm or less, scattering of transmitted light is suppressed and the transparency is excellent.
The pH of the colloidal silica aqueous dispersion is particularly preferably in the range of 2-6. When the pH is within this range, the stability of silanol, which is a hydrolyzate of alkoxysilane, is excellent, the dehydration condensation reaction is suppressed, and the increase in the viscosity of the coating solution is suppressed.

(Aqueous resin dispersion)
The aqueous coating composition according to the present invention may contain a water-dispersed resin having a pH of 2 to 6 for the purpose of adjusting film physical properties. When the pH of the water-dispersed resin is within this range, the stability of silanol, which is a hydrolyzate of alkoxysilane, is excellent, and an increase in the viscosity of the coating solution can be suppressed.
As the type of the water-dispersed resin, a styrene butadiene resin, an acrylonitrile butadiene resin, a polyurethane resin, an ethylene vinyl acetate resin, a polyester resin, and an acrylic resin are preferable because the flexibility of the film is improved.

[Antistatic agent]
You may add an antistatic function to the hard-coat layer in this invention as needed. In order to add an antistatic function, an ionic antistatic agent such as a cation, anion, or betaine may be added to the aqueous coating composition, and tin oxide, indium oxide, zinc oxide, titanium oxide, Fine particles made of a metal oxide such as magnesium oxide or antimony oxide may be added.

[Other additive materials]
In the hard coat layer in the present invention, a matting agent and wax may be used as necessary to adjust the surface characteristics, particularly the friction coefficient. As the matting agent, organic and inorganic materials such as silica, calcium carbonate, magnesium carbonate, barium sulfate, polystyrene, polystyrene-divinylbenzene copolymer, polymethyl methacrylate, crosslinked polymethyl methacrylate, melamine, and benzoguanamine can be used. . Examples of waxes that can be used include paraffin wax, microwax, polyethylene wax, polyester wax, carnauba wax, fatty acid, fatty acid amide, and metal soap.
In order to improve the coating property, a surfactant may be added to the coating solution. Although it does not specifically limit as surfactant, Any surfactant of aliphatic, aromatic, and fluorine type may be sufficient, and nonionic, anionic, and cationic surfactants can be used.

The hard coat layer in the present invention is obtained by applying the aqueous coating composition to at least one surface of a polymer film and drying at a temperature of 160 ° C. or higher to form a cured film.
The method for forming the cured film is not particularly limited, and a known coating method can be appropriately selected according to the purpose. For example, a spin coater, a roll coater, a bar coater, a curtain coater and the like can be mentioned. In any method, the aqueous coating composition is applied to a desired surface and then dried to form a layer. Here, the drying method is not particularly limited, and a commonly used method can be appropriately selected. At this time, in order to sufficiently cure the cured film, the drying temperature is preferably 160 ° C. or higher. In particular, the drying temperature is preferably 170 ° C to 220 ° C, and more preferably 180 ° C to 210 ° C. When the drying temperature is 160 ° C. or higher, the film is sufficiently cured and sufficient film hardness is obtained. On the other hand, when the temperature is 220 ° C. or lower, the deformation of the polyester support is suppressed, which is preferable. Also, in order to promote drying in a short time without causing thermal damage, the drying time is preferably 10 seconds to 5 minutes, more preferably 20 seconds to 3 minutes under moderate temperature conditions. is there.

-Refractive index adjustment layer-
The light diffusion film for LED illumination of the present invention may be provided with a refractive index adjusting layer as the outermost surface layer. The refractive index of the refractive index adjusting layer is preferably 1.3 or more and less than 1.6, more preferably 1.3 to 1.5, and still more preferably 1.3 to 1.45. . By providing the refractive index adjustment layer, interface reflection with air is suppressed and light efficiency can be improved.

The thickness of the refractive index adjustment layer is preferably 10 nm to 200 nm, and more preferably 50 nm to 150 nm. By setting the thickness to 10 nm or more, an effect of reducing the interface reflectance in the visible light region appears, and by setting the thickness to 200 nm or less, the reflectance reduction effect in the visible light region is maximized.
On the other hand, when it is necessary to suppress interference fringes, a refractive index adjustment layer having a thickness of 2 μm to 10 μm is preferably used from the viewpoint of achieving both reduction in reflectance and suppression of interference fringes.

  As a material used for the refractive index adjustment layer, commercially available products include fluorine-based materials such as Cytop CTL-107MK (refractive index of 1.34) manufactured by Asahi Glass Co., Ltd., porous films such as silica airgel, or microscopic materials. The thing containing a hollow particle etc. can be mentioned.

<The manufacturing method of the light-diffusion film for LED lighting>
The manufacturing method of the light-diffusion film for LED lighting of this invention will not be specifically limited if it is a method which can form the light-diffusion film for LED lighting of the said structure. Below, an example of the manufacturing method of the light-diffusion film for LED illumination is demonstrated.

  First, a diffusion layer coating solution containing at least the aforementioned particles and binder is applied onto a transparent substrate to form a diffusion layer. This is referred to as a first film prepared in advance. Then, a transparent substrate on which a diffusion layer is separately formed is prepared, or a transparent substrate on which no diffusion layer is provided is prepared. This is referred to as a second film. The diffusion layer in the first film prepared in advance and the transparent substrate not provided with the diffusion layer or diffusion layer of the second film are bonded with an adhesive. When the diffusion layer has a bonding function, the diffusion layer is bonded without using an adhesive.

  When providing a surface coating layer on the light diffusion film for LED illumination of the present invention, after the above-mentioned adhesion, it is immersed or coated in a surface coating layer coating solution and then dried.

<Application>
The light-diffusion film for LED lighting of this invention can be used suitably for the apparatus using LED lighting by the advantage. Furthermore, the use as a light diffusion film of a backlight unit of a liquid crystal display device used for a mobile phone, a personal computer monitor, a television, a liquid crystal projector, etc. is exemplified.
In addition, when the light-diffusion film for LED illumination of this invention is used, deletion of the real image of a LED light source and high light transmittance are compatible. Moreover, it becomes a highly rigid light diffusion film for LED lighting.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. In the following description, “parts” and “%” mean “parts by mass” and “mass%”, and “average particle diameter” means “weight average particle diameter” unless otherwise specified.

[Liquid formula 1]
-Distilled water: 155 parts-Surfactant (Sanyo Chemical Industry Co., Ltd., NAROACTY CL-95):
3 parts / particles (Sekisui Plastics Co., Ltd., SBX-12, polystyrene particles, average particle size 12 μm, refractive index 1.59): 206 parts / water dispersible polymer (polyurethane resin, Mitsui Chemicals, W6010, (Solid content 30%): 598 parts, crosslinking agent (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%):
38 parts

[Liquid formula 2]
-Distilled water: 155 parts-Surfactant (Sanyo Chemical Industry Co., Ltd., NAROACTY CL-95):
3 parts / particles (Sekisui Chemicals Co., Ltd., SBX-17, polystyrene particles, average particle size 17 μm, refractive index 1.59): 206 parts / water dispersible polymer (polyurethane resin, Mitsui Chemicals, W6010, Solid content 30%):
598 parts, cross-linking agent (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%):
38 parts

[Liquid formula 3]
-Distilled water: 155 parts-Surfactant (Sanyo Chemical Industry Co., Ltd., NAROACTY CL-95):
3 parts / particle (Momentive, Tospearl 1110, silicone particles, average particle size 11 μm, refractive index 1.45): 206 parts / water dispersible polymer (polyurethane resin, Mitsui Chemicals, W6010, solid content 30%): 598 parts, cross-linking agent (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%):
38 parts

[Liquid formulation 4]
-Distilled water: 155 parts-Surfactant (Sanyo Chemical Industry Co., Ltd., NAROACTY CL-95):
3 parts / particles (manufactured by Sekisui Plastics Co., Ltd., MBX-20, acrylic particles, average particle size 20 μm, refractive index 1.49): 206 parts / water dispersible polymer (polyurethane resin, Mitsui Chemicals, W6010, (Solid content 30%): 598 parts, crosslinking agent (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%):
38 parts

[Liquid prescription 5]
-194 parts of distilled water-Surfactant (Sanyo Chemical Industry Co., Ltd., NAROACTY CL-95):
4 parts / particles (Sekisui Plastics Co., Ltd., SBX-4, polystyrene particles, average particle size 4 μm, refractive index 1.59): 264 parts / ultrafine particle dispersion (Nissan Chemical Industries, Snow Tex C, silica particles, average particle size 0.01 μm to 0.02 μm, solid content 20%): 112 parts Water-dispersible polymer (polyurethane resin, DMS NeoResins Inc., NeoRez R-600, solid content 33%) : 400 parts Crosslinking agent (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%):
26 copies

[Liquid formulation 6]
-Distilled water: 155 parts-Surfactant (Sanyo Chemical Industry Co., Ltd., NAROACTY CL-95):
3 parts / particles (manufactured by Sekisui Plastics Co., Ltd., MBX-8, acrylic particles, average particle size 8 μm, refractive index 1.49): 206 parts / water dispersible polymer (polyurethane resin, Mitsui Chemicals, W6010, (Solid content 30%): 598 parts, crosslinking agent (Nisshinbo Co., Ltd., Carbodilite V-02-L2, solid content 40%):
38 parts

[Example 1]
Prepare two PET films (biaxially stretched, film thickness 300 μm, refractive index 1.67), apply liquid formulation 1 on one PET film using a wire bar, and heat in an oven at 130 ° C. for 2 minutes. Cured to produce a 20 μm diffusion layer. On this diffusion layer, an adhesive (manufactured by Toyo Ink Co., Ltd., LIS805 / LCR-901, refractive index 1.5) was applied with an applicator to a thickness of 15 μm, and then heated in an oven at 100 ° C. for 2 minutes to form an adhesive layer After forming the film, the other PET film was bonded to the adhesive layer to produce a film 1. The total applied amount (basis weight) of particles in the film 1 was 10.2 g / m ² .

[Example 2]
[Easily adhesive layer]
After the corona discharge treatment was applied to the outer surface of the film 1 produced in the same manner as in Example 1, the following coating solution 12-1 was applied, dried at 120 ° C. for 2 minutes, and an easily adhesive layer having a thickness of 0.11 μm. Formed.

(Coating liquid 12-1)
-Takelac WS-4000: 5.0 parts (solid content concentration 30%, manufactured by Mitsui Chemicals)
・ Surfactant: 0.3 part (Narrow Acty HN-100, manufactured by Sanyo Chemical Industries)
-Surfactant: 0.3 part (Sandet BL, solid content concentration 43%, manufactured by Sanyo Chemical Industries)
・ Water: 94.4 parts

[Hard coat layer]
The following coating liquid 12-2 was applied onto the easy-adhesion layer by a bar coating method, dried at 200 ° C. for 80 seconds to form a cured film having a thickness of 2.6 μm, and thus a film 2 with a hard coat layer was obtained.

(Coating liquid 12-2)
Tetramethoxysilane: 5.0 parts (KBM-04, manufactured by Shin-Etsu Chemical Co., Ltd.)
3-glycidoxypropyltrimethoxysilane: 5.0 parts (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.)
Acetic acid aqueous solution (1%, pH = 4.1): 29.2 parts Curing aid: 0.4 parts (aluminum chelate A (W), manufactured by Kawaken Fine Chemical Co., Ltd.)
Colloidal silica: 60.0 parts (Snowtex O, average particle size 10 to 20 nm, solid content concentration 20%, pH = 2.6, manufactured by Nissan Chemical Co., Ltd.)
Surfactant: 0.2 parts (Narrow Acty HN-100, manufactured by Sanyo Chemical Industries)
-Surfactant: 0.2 part (Sandet BL, solid content concentration 43%, manufactured by Sanyo Chemical Industries)

[Example 3]
A CYTOP (manufactured by Asahi Glass Co., Ltd., CTL-107MK, refractive index 1.34) was provided on one side of the film 1 with a film thickness of 100 nm to prepare a film 3.

[Example 4]
Prepare two PET films (biaxially stretched, film thickness 300 μm, refractive index 1.67), apply liquid formulation 2 on one PET film using a wire bar, and heat in an oven at 130 ° C. for 2 minutes. Cured to produce a 20 μm diffusion layer. On this diffusion layer, an adhesive (manufactured by Toyo Ink Co., Ltd., LIS805 / LCR-901, refractive index 1.5) was applied with an applicator to a thickness of 15 μm, and then heated in an oven at 100 ° C. for 2 minutes to form an adhesive layer After forming the film, the other PET film was bonded to the adhesive layer to prepare a film 4. The total applied amount (basis weight) of particles in the film 4 was 10.2 g / m ² .

[Example 5]
Prepare two PET films (biaxially stretched, film thickness 300 μm, refractive index 1.67), apply liquid formulation 3 on one PET film using a wire bar, and heat in an oven at 130 ° C. for 2 minutes. Cured to produce a 30 μm diffusion layer. On this diffusion layer, an adhesive (LIS805 / LCR-901, refractive index 1.5, manufactured by Toyo Ink Co., Ltd.) was applied with a thickness of 15 μm by an applicator, and then heated in an oven at 100 ° C. for 2 minutes to form an adhesive layer After forming the film, the other PET film was bonded to the adhesive layer to produce a film 5. The total applied amount (basis weight) of particles in the film 5 was 15.3 g / m ² .

[Example 6]
Prepare two PET films (biaxially stretched, film thickness 300 μm, refractive index 1.67), apply liquid formulation 4 on one PET film using a wire bar, and heat in an oven at 130 ° C. for 2 minutes. Cured to produce a 160 μm diffusion layer. On this diffusion layer, an adhesive (LIS805 / LCR-901, manufactured by Toyo Ink Co., Ltd., refractive index 1.5) was applied with an applicator to a thickness of 20 μm, and then heated in an oven at 100 ° C. for 2 minutes to form an adhesive layer. After forming the film, the other PET film was bonded to the adhesive layer to produce a film 6. The total applied amount (basis weight) of particles in the film 6 was 81.7 g / m ² .

[Comparative Example 1]
Prepare two PET films (biaxially stretched, film thickness 300 μm, refractive index 1.67), apply liquid formulation 5 on one PET film using a wire bar, and heat in an oven at 130 ° C. for 2 minutes. Cured to produce a 10 μm diffusion layer. On this diffusion layer, an adhesive (manufactured by Toyo Ink Co., Ltd., LIS805 / LCR-901, refractive index 1.5) was applied with an applicator to a thickness of 15 μm, and then heated in an oven at 100 ° C. for 2 minutes to form an adhesive layer Then, the other PET film was bonded to the adhesive layer to produce a comparative film 1. The total applied amount (basis weight) of particles in the comparative film 1 was 6.1 g / m ² .

[Comparative Example 2]
The comparative film 2 was produced based on Example 1 of the patent 4129275 specification. The particles used here are acrylic resin particles (Techpolymer MBX-5: Refractive index 1.47: Average particle size 5.0 μm: Sekisui Chemical Co., Ltd.).

[Comparative Example 3]
The comparative film 3 was produced according to the Example of Unexamined-Japanese-Patent No. 2010-77179. The particles used here were crosslinked styrene resin particles (SBX-8 manufactured by Sekisui Plastics Co., Ltd., average particle diameter 8 μm, refractive index 1.59), and barium sulfate particles (B-1 manufactured by Sakai Chemical Co., Ltd.). The average particle diameter is 0.75 μm, and the refractive index is 1.64).

[Comparative Example 4]
Prepare two PET films (biaxially stretched, film thickness 300 μm, refractive index 1.67), apply liquid formulation 6 on one PET film using a wire bar, and heat in an oven at 130 ° C. for 2 minutes. Cured to produce a 20 μm diffusion layer. On this diffusion layer, an adhesive (manufactured by Toyo Ink Co., Ltd., LIS805 / LCR-901, refractive index 1.5) was applied with an applicator to a thickness of 15 μm, and then heated in an oven at 100 ° C. for 2 minutes to form an adhesive layer Then, the other PET film was bonded to the adhesive layer to prepare a comparative film 4. The total applied amount (basis weight) of particles in the comparative film 4 was 10.2 g / m ² .

<Evaluation and measurement method>
(Refractive index of particles)
Particles are placed on a slide glass, an organic compound having a known refractive index or a mixture thereof (compound for measurement) is added, sandwiched between cover glasses, and observed at 25 ° C. using a (transmission) optical microscope. Was determined, and the refractive index of the measurement compound was measured with a multiwavelength Abbe refractometer (DR-M2, manufactured by Atago Co., Ltd.). The measurement wavelength was 589 nm and the measurement temperature was 25 ° C.

(Lamp image evaluation)
A white LED light source with a power consumption of 1 W was placed at a position of 50 mm from one surface of the light diffusion plate, and the presence or absence of an actual image of the LED light source was evaluated by viewing from the opposite side of the light source through the light diffusion plate. . A circle indicates a case where the actual image of the LED light source is not confirmed, and a circle indicates a case where the actual image of the LED light source is confirmed.

(Evaluation of haze)
The haze value was measured based on JIS K7136: 2000 using NDH-5000 made by Nippon Denshoku.

(Measurement of total light transmittance)
Using Nippon Denshoku NDH-5000, the total light transmittance was measured according to JIS K7361-1: 1997.

From the results of Table 1, it can be seen that in the LED light diffusion films of Examples 1 to 6, the actual image of the LED light source is erased and the light transmittance is less decreased. In particular, in Examples 2 and 3 in which a surface coating layer such as a hard coat layer or a refractive index adjustment layer was provided, the total light transmittance was reduced without reducing the haze value after the actual image of the LED light source was erased. It has improved.
On the other hand, in Comparative Examples 1, 2, and 4 using particles having a weight average particle diameter smaller than 10 μm, the actual image of the LED light source was not erased. In Comparative Example 3, the actual image of the LED light source was erased by using two kinds of particles having a weight average particle diameter smaller than 10 μm, but the total light transmittance was remarkably reduced.

Here, Young's modulus (JIS K7161) and flexural modulus (JIS K7171) are generally known as indices representing rigidity. It is known that the amount of strain due to bending, which is important in this study, is generally inversely proportional to the cube of the film thickness when a constant size and a constant stress are applied. Therefore, when the film thickness is doubled, the strain is reduced to 1/8. The amount of strain can be greatly reduced by increasing the thickness by pasting together.
On the other hand, the comparative example 3 is a light diffusing plate produced from a methacrylic resin composition containing particles as shown in FIG. 7 and does not have two or more substrates, and thus is inferior in rigidity.

10, 11, 12 Transparent substrate 16, 16A, 16B, 17 Diffusion layer 14, 14A, 14B Adhesive layer 18, 20 Surface coating layer 22 First particle group 24 Second particle group

Claims (5)

Having two or more transparent substrates,
A light diffusing film for LED lighting containing particles having a weight average particle diameter of 10 μm or more and 20 μm or less together with a binder in a portion other than the outermost layer.   The light diffusing film for LED lighting according to claim 1, wherein at least one of the transparent substrates is a biaxially stretched PET film.   The light diffusion film for LED lighting according to claim 1 or 2, wherein the particles are contained together with the binder between the two transparent substrates facing each other.   4. The structure according to claim 1, wherein at least one of a hard coat layer having a thickness of 2 μm to 10 μm and a layer having a refractive index of 1.3 to 1.6 and a thickness of 10 nm to 200 nm is provided on the outermost surface. The light-diffusion film for LED illumination of Claim 1. LED lighting light-diffusing film according to any one of claims 1 to 4 total application amount is ^10g / ^{m 2 ~100g} / m 2 of said particles.

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