WO2019208769A1

WO2019208769A1 - Light diffusing formed body, transparent screen film, and method for evaluating light diffusing formed body

Info

Publication number: WO2019208769A1
Application number: PCT/JP2019/017942
Authority: WO
Inventors: 渉赤塚
Original assignee: 三菱瓦斯化学株式会社
Priority date: 2018-04-27
Filing date: 2019-04-26
Publication date: 2019-10-31
Also published as: JPWO2019208769A1; CN112005134A

Abstract

The present invention provides, for example, a light diffusing formed body and a transparent screen film for which viewing angle characteristics and color reproducibility are particularly exceptional. To that end, a light diffusing formed body according to the present invention is made to include a transparent resin binder and light-diffusing particles and is made to be such that when a flat sample of the light diffusing formed body is placed at a reference position and irradiation light is irradiated toward the point of intersection between a perpendicular, which is perpendicular to the flat sample placed at the reference position, and the flat sample at an axis of incidence inclined by 10° in relation to the perpendicular, the degree D of diffusion calculated using equation (1) from a measured value for the relative transmitted light intensity of the light that has passed through the flat sample is at least 20. (In equation (1), the values of D, I₅, I₂₀, and I₇₀ are as defined in the description.)

Description

Light diffusion molded body, transparent screen film, and evaluation method of light diffusion molded body

The present invention relates to a light diffusion molded article, for example, a light diffusion molded article suitable for a transparent screen for projecting and displaying an image, a transparent screen film, and a method for evaluating the light diffusion molded article.

Conventionally, for example, transparent screens for displaying images for product advertisements are known (for example, Patent Documents 1 and 2). As such a transparent screen, a thin resin layer to which fine particles are added is employed, and an image projected from the projector is displayed on the transparent screen.

Japanese Patent No. 5752834 WO2016 / 0931181

In a light diffusion molded body including a conventional transparent screen or the like, it is required to reach a practical level in terms of performance such as transparency.

However, there are many conventional light diffusion molded articles that cannot be said to have sufficient performance. For example, when a light diffusion molded body is used as a transparent screen that displays a moving image or a still image, the visibility of the projected image may not always be good.

For example, when a light diffusion molded body in which transmitted light is not sufficiently diffused is used for a transparent screen, the viewing angle becomes narrow, and it is difficult to visually recognize an image on the transparent screen from a position away from the front of the transparent screen. There was a problem.

In addition, in a video projected on a transparent screen based on certain specific video data, a color reproducibility such that a specific color, for example, blue, is emphasized compared to a video displayed on another display device based on the same video data. May decrease. For example, in the transparent screen film disclosed in Patent Document 1, the blue color of the image projected from the projector is emphasized more than necessary. This is considered to be due to the fact that the light-diffusing particles have a small particle diameter, and thus the light-reducing efficiency of short-wavelength light, that is, blue light is large, and the light is more diffused.

As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention are particularly good in terms of viewing angle characteristics and color reproducibility, and are particularly suitable for transparent screen applications, And it discovered that the film for transparent screens, etc. were realizable, and came to complete this invention.
That is, a light diffusion molded product and a transparent screen film that can achieve the above-described excellent characteristics were realized.
The present invention relates to a light diffusion molded article, a transparent screen film, and the like shown below.

(1) A light diffusion molded article containing a transparent resin binder and light diffusion particles,
A plane sample of the light diffusion molded body is arranged at a reference position,
Measured when irradiating incident light toward an intersection of the perpendicular and the planar sample along an incident axis inclined by 10 ° with respect to a perpendicular perpendicular to the planar sample arranged at the reference position, A light diffusion molded article in which the value of the diffusivity D defined by the following formula (1) is 20 or more from the value of the relative transmitted light intensity of the transmitted light transmitted through the planar sample.

(However, in the above formula (1),
D is the diffusivity,
I ₅ , I ₂₀ , and I ₇₀ are planes that are perpendicular to the planar sample that includes the perpendicular and is at the reference position when the incident light having a constant intensity is incident on the intersection. The angle θ with respect to the perpendicular is 5 °, 20 °, and 70 °, respectively, and is on the virtual vertical plane perpendicular to the plane including the normal and the incident axis, and from the intersection The relative transmitted light intensity values of the transmitted light at observation points where the distances are equal to each other are shown. )
(2) From the spectrum of transmitted light that diffuses in a direction that forms an angle of 45 ° with respect to the planar sample when the planar sample placed at the reference position is irradiated with incident light along the perpendicular. In the above (1), the values of a * and b * expressed in the CIE 1976 color space calculated by a method based on JIS-Z-8781-4 satisfy the following conditions (i) and (ii): ).
(I) The value of a * is −5 or more and 5 or less.
(Ii) The value of b * is −15 or more and 15 or less.
(3) The value of the saturation C * expressed in the CIE 1976 color space calculated by a method based on JIS-Z-8781-4 from the spectrum of the transmitted light further satisfies the following condition (iii): The light-diffusion molded object as described in said (2).
(Iii) C * is −10 or more and 10 or less.
(4) Transmitted light intensity of reference transmitted light that travels along the perpendicular line through the planar sample placed at the reference position when the incident light is irradiated along the incident axis with respect to the intersection. an observation point on the vertical plane transmitted light is observed with a relative intensity of transmitted light 1/2 relative to the angle theta ₁ with respect to the perpendicular line passing through said intersection point is 10.8 ° or more, The light diffusion molded article according to any one of (1) to (3) above.
(5) Transmitted light intensity of reference transmitted light that travels along the perpendicular through the planar sample placed at the reference position when the incident light is irradiated along the incident axis with respect to the intersection. The angle θ _{2 of the} line passing through the observation point on the vertical plane where the transmitted light having the relative transmitted light intensity of 1/10 is observed with respect to the perpendicular and the perpendicular is 30 ° or more, The light diffusion molded article according to any one of 1) to (3).
(6) The light diffusion molded article according to any one of (1) to (5), wherein the value of the diffusivity D is 80 or less.
(7) The light diffusion particle is an oxide of at least one element selected from the group consisting of Bi, Nd, Si, Al, Zr, and Ti, a composite oxide, and the oxide and the composite oxidation The light diffusion molded article according to any one of the above (1) to (6), comprising any one or more of at least any mixture of the above substances.
(8) The above (7), wherein the light diffusing particles contain at least one of Bi oxide, composite oxide, and a mixture of at least one of the oxide and the composite oxide. The light-diffusion molded object of description.
(9) The light diffusion molded article according to any one of (1) to (8), wherein the light diffusion particles have a Z average particle diameter of 150 to 3500 nm.
(10) The light diffusion molded article according to any one of (1) to (9), wherein the number average particle diameter of the light diffusion particles contained in the light diffusion molded article is 100 to 2300 nm.
(11) The above (1) to (10), wherein the particle size of the light diffusing particles of 15% or more based on the number of the light diffusing particles contained in the light diffusing molded product is in the range of 300 to 2000 nm. The light-diffusion molded object as described in any one of these.
(12) The light diffusion molded article according to any one of (1) to (11), wherein 0.001 to 3 parts by mass of the light diffusion particles are contained with respect to 100 parts by mass of the transparent resin binder.
(13) The light diffusion molded article according to any one of (1) to (12), wherein the polydispersity index of the light diffusion particles is 0.8 or less.
(14) The light diffusion molded article according to any one of (1) to (13), wherein the transparent resin binder contains a thermoplastic resin.
(15) The light diffusion molded article according to (14), wherein the thermoplastic resin contains a polycarbonate resin.
(16) A transparent screen film comprising the light diffusion molded article according to any one of (1) to (15) above.

In the light diffusion molded article of the present invention and the transparent screen film containing the transparent resin binder and the light diffusing particles, the transmitted light traveling in the direction away from the incident direction of the incident light also has a certain intensity or more. Have. For this reason, it can be said that the light-diffusion molded object of this invention and the film for transparent screens are especially excellent in the viewing angle characteristic, and has high color reproducibility.

It is a front view which shows an example of the measuring apparatus for measuring the transmitted light distribution of a light-diffusion molded object. It is a top view which shows an example of the measuring apparatus for measuring the transmitted light distribution of a light-diffusion molded object. It is a figure which shows roughly the measuring method of the particle diameter based on the cross-sectional observation of a resin film. It is a figure which shows roughly the measuring method of the spectral spectrum of the light ray which permeate | transmitted the light-diffusion molded object. It is a graph which shows the spectral spectrum (relative transmitted light intensity) of the light ray which permeate | transmitted the light-diffusion molded object of an Example and a comparative example.

Hereinafter, the present invention will be described in detail. In addition, this invention is not limited to the following embodiment, In the range which has the effect of invention, it can change arbitrarily and can implement.

[Light diffusion molding]
The light diffusion molded article of the present invention includes a transparent resin binder and light diffusion particles. The light diffusion molded body is particularly suitable for use as a transparent screen film because it can diffuse incident light over a wide range and has high viewing angle characteristics. The transmitted light traveling in the direction away from the incident direction also has a certain intensity or more. For this reason, it can be said that the light-diffusion molded object of this invention and the film for transparent screens are especially excellent in light diffusibility, and has high color reproducibility.

In the light diffusion molded body, 0.001 to 3 parts by mass of light diffusion particles (about 0.001 to about 3.0% by mass in the light diffusion molded body) is contained with respect to 100 parts by mass of the transparent resin binder. It is preferable. More preferably, the light diffusion molded article contains 0.01 to 1 part by weight of light diffusion particles with respect to 100 parts by weight of the transparent resin binder, and more preferably, light diffusion particles with respect to 100 parts by weight of the transparent resin binder. In an amount of 0.03 to 0.5 parts by mass, and particularly preferably 0.1 to 0.3 parts by mass of light diffusing particles with respect to 100 parts by mass of the transparent resin binder.
By adjusting the content of the light diffusing particles to the above-mentioned range, high transparency of the light diffusing molded body is ensured, and a sufficient scattering effect of the projection light is obtained, and image visibility such as color reproducibility is obtained. Will also be good.

<Transparent resin binder>
A transparent resin binder is used as a main constituent material of the light diffusion molded body. In order to improve the strength and durability of the transparent screen film, the transparent resin binder preferably contains a hard thermoplastic resin. Furthermore, in order to improve the transparency of the transparent screen film, it is preferable to include a highly transparent thermoplastic resin.
Specifically, the thermoplastic resin used as a component of the transparent resin binder is selected from the group consisting of polycarbonate resin, polyester resin, acrylic and methacrylic resin, polyolefin resin, cellulose resin, vinyl resin, and polystyrene resin. It is preferable to contain at least one kind.
In particular, the transparent resin binder preferably contains at least one selected from a polycarbonate resin and a polyester resin among the above-mentioned options of the thermoplastic resin.

For example, as the above polycarbonate resin, a — [O—R—OCO] — unit (R is an aliphatic group, an aromatic group, or both an aliphatic group and an aromatic group) containing a carbonate ester bond in the molecular main chain. And those having a linear structure or a branched structure) are not particularly limited. However, from the viewpoint of impact resistance and heat resistance, and stability as an aromatic dihydroxy compound, and also from the viewpoint of easy availability of those containing a small amount of impurities contained therein, aromatic polycarbonate is cited as a more preferable one. It is done. Examples of the aromatic polycarbonate include those having a bisphenol A skeleton.

As described above, the specific type of the polycarbonate resin is not limited, but examples thereof include a polycarbonate polymer obtained by reacting a dihydroxy compound and a carbonate precursor. At this time, in addition to the dihydroxy compound and the carbonate precursor, a polyhydroxy compound or the like may be reacted. Further, a method of reacting carbon dioxide with a cyclic ether using a carbonate precursor may be used. Further, the polycarbonate polymer may be a homopolymer composed of one type of repeating unit or a copolymer having two or more types of repeating units. At this time, the copolymer can be selected from various copolymerization forms such as a random copolymer and a block copolymer.

The method for producing the polycarbonate resin is not particularly limited, and any method can be adopted. Examples include an interfacial polymerization method, a melt transesterification method, a pyridine method, a ring-opening polymerization method of a cyclic carbonate compound, and a solid phase transesterification method of a prepolymer.

The molecular weight of the polycarbonate resin is preferably 10,000 to 35,000, more preferably 10,000 or more in terms of viscosity average molecular weight converted from the solution viscosity measured at a temperature of 25 ° C. using methylene chloride as a solvent. More preferably, it is 11,000 or more, more preferably 11,500 or more, and still more preferably 12,000 or more. Moreover, the viscosity average molecular weight of polycarbonate resin becomes like this. Preferably it is 32,000 or less, More preferably, it is 29,000 or less. By making the viscosity average molecular weight more than the lower limit of the above range, the mechanical strength of the resin molding of the present invention can be further improved, and by making the viscosity average molecular weight not more than the upper limit of the above range, It is possible to improve by suppressing the decrease in fluidity, and to improve the molding processability and easily perform the thin-wall molding process.
Two or more types of polycarbonate resins having different viscosity average molecular weights may be mixed and used, and in this case, a polycarbonate resin having a viscosity average molecular weight outside the above-mentioned preferred range may be mixed.
The viscosity average molecular weight [Mv] is obtained by using methylene chloride as a solvent and obtaining an intrinsic viscosity [η] (unit: dl / g) at a temperature of 25 ° C. using an Ubbelohde viscometer. , Η = 1.23 × 10 ⁻⁴ Mv ^0.83 . The intrinsic viscosity [η] is a value calculated from the following equation by measuring the specific viscosity [η _sp ] at each solution concentration [C] (g / dl).

Moreover, as the above-mentioned polyester resin, for example, PETG (polyethylene terephthalate modified with glycol by cyclohexanedimethanol) or the like is used.

Further, the transparent resin binder may contain a photocurable resin, a thermosetting resin, or the like as a component other than the thermoplastic resin. In this case, the transparent resin binder preferably contains 80% by mass or more of a thermoplastic resin, and more preferably contains 90% by mass or more of a thermoplastic resin.

The photocurable resin contained in the transparent resin binder may be any of an ultraviolet curable resin and an electron beam curable resin, such as an acrylic resin, a silicone resin, and an ester resin. Specific examples of UV curable resins include UV curable resins having an acryloyl group in the molecule, such as epoxy acrylate, urethane acrylate, polyester acrylate, polyol acrylate oligomers, polymers and monofunctional, bifunctional, Alternatively, a polyfunctional polymerizable (meth) acrylic monomer such as tetrahydrofurfuryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethylolpropane triacrylate, Mixtures of monomers, oligomers, polymers and the like such as pentaerythritol triacrylate and pentaerythritol tetraacrylate are used. In addition, you may mix | blend the photoinitiator etc. which are mix | blended normally with a photocurable resin.
Examples of the thermosetting resin contained in the transparent resin binder include phenol resin, polyimide resin, bismaleimide triazine resin, crosslinkable polyphenylene oxide, curable polyphenylene ether, melamine resin, urea resin, epoxy resin, and unsaturated polyester. Resin, alkyd resin, diallyl phthalate resin, xylene resin, (meth) acrylic resin, cresol novolac epoxy resin, phenol novolac epoxy resin, biphenyl epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic ring Epoxy resins, halogenated epoxy resins, spirocyclic epoxy resins, bisphenol A, resorcinol and other novolac epoxy resins, bisphenol A epoxy resins, brominated bisphenol A Epoxy resin, etc. is used.

<Light diffusion particles>
The light diffusion molded body contains atomized light diffusion particles. As the light diffusion particles, for example, those containing a metal oxide are used. More specifically, the light diffusing particles include, for example, an oxide of at least one element selected from the group consisting of Bi, Nd, Si, Al, Zr, and Ti, a composite oxide, and the oxide And at least one of the composite oxides is preferably included. More preferably, the light diffusing particles contain at least one selected from bismuth oxide, zirconium oxide, silica, titania (titanium oxide), and alumina. As the light diffusion particles, particles containing bismuth oxide, that is, particles containing a bismuth oxide, a composite oxide, and a mixture of at least one of the oxide and the composite oxide are particularly preferable. By using a film for a screen containing these light diffusing particles, particularly the above-mentioned light diffusing particles mentioned as a preferable option, the color reproducibility of an image during projector projection can be particularly improved.

As the metal oxide light diffusing particles used in the present invention, those subjected to surface treatment may be used. As the surface treatment agent, inorganic materials and / or organic materials are preferable. Specific examples of the surface treating agent include metal oxides such as alumina, silica, and zirconia, silane coupling agents, titanium coupling agents, organic materials such as organic acids, polyols, and silicones.

The light diffusing particles preferably have a Z average particle diameter of 150 nm to 3500 nm. The Z average particle diameter of the light diffusing particles is more preferably 180 nm to 3000 nm, and further preferably 200 nm to 2000 nm. Thus, a light diffusion molded article that employs light diffusion particles having a large diameter compared to light diffusion particles used in a conventional transparent screen for projection, for example, light diffusion particles having a particle diameter of about several tens of nanometers, As will be described in detail later, a transparent screen having excellent light transmittance, light diffusibility, and color reproducibility can be realized.
The Z average particle diameter referred to in the present invention is data obtained by analyzing measurement data of a dynamic light scattering method such as a particle dispersion using a cumulant analysis method.

In the cumulant analysis, the average value of the particle diameter and the polydispersity index (PDi) are obtained. In the present invention, this average particle diameter is defined as the Z average particle diameter.
Specifically, it is as follows. First, the work of fitting a polynomial to the logarithm of the G1 correlation function obtained by measurement is called cumulant analysis, and the following formula LN (G1) = a + bt + ct ² + dt ³ + et ⁴ +...
Is called the second-order cumulant or Z-average diffusion coefficient.
A value obtained by converting the value of the constant b into a particle diameter using the viscosity of the dispersion medium and some apparatus constants is the Z average particle diameter. The value of the Z average particle diameter is the most important and stable value obtained by the dynamic light scattering method, and is a value suitable for quality control purposes as an index of dispersion stability. As for the coefficient c of the square term, the value 2c / b ² is called a polydispersity index (PDi).
The Z average particle size, which is an index of dispersibility in the present invention, can be specifically measured using the following method.
That is, a particle size measuring machine using dynamic light scattering, such as a Zetasizer Nano ZS measuring device manufactured by Malvern Co., Ltd., after the light diffusing particles are put into pure water and the particles are dispersed using ultrasonic waves. And the value of the Z average particle diameter can be determined.

The polydispersity index of the light diffusing particles is preferably 0.8 or less. Furthermore, the polydispersity index of the light diffusing particles is more preferably 0.7 or less, and particularly preferably 0.5 or less. Thus, by using light diffusing particles having a small polydispersity index value, light diffusing particles having extremely large diameters or extremely small diameters can be removed from the light diffusion molded article.

[Other components contained in light diffusion molded article]
For example, the following additives may be included as components other than the transparent resin binder and the light diffusion particles in the light diffusion molded body. For example, in a light diffusion molded article used as a transparent screen film, it was selected from the group consisting of a heat stabilizer, an antioxidant, a flame retardant, a flame retardant aid, an ultraviolet absorber, a release agent, and a colorant. At least one additive. An antistatic agent, a fluorescent whitening agent, an antifogging agent, a fluidity improving agent, a plasticizer, a dispersing agent, an antibacterial agent and the like may be added as long as the desired physical properties are not significantly impaired.

The light diffusion molded article of the present invention preferably contains an antioxidant.
Antioxidants include phenolic antioxidants, amine antioxidants, phosphorus antioxidants, thioether antioxidants, phosphorus antioxidants and phenolic antioxidants (more preferably hinders). Dophenol antioxidants) are preferred. Among these, phosphorus-based antioxidants are particularly preferable because they can form a resin molded article excellent in hue.
Among the phosphorus antioxidants, phosphite stabilizers are preferable, and the phosphite stabilizer is preferably a phosphite compound represented by the following formula (1) or (2).

(In Formula (1), R ¹ and R ² each independently represents an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms.)

(In Formula (2), R ³ to R ⁷ each independently represents a hydrogen atom, an aryl group having 6 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms.)

In the above formula (1), the alkyl groups represented by R ¹ and R ² are preferably each independently a linear or branched alkyl group having 1 to 10 carbon atoms. When at least one of R ¹ and R ² is an aryl group, an aryl group represented by any of the following general formulas (1-a), (1-b), or (1-c) is preferable.

(In the formula (1-a), R ^A each independently represents an alkyl group having 1 to 10 carbon atoms. In the formula (1-b), R ^B each independently represents an alkyl group having 1 to 10 carbon atoms. Represents an alkyl group.)

The content of the antioxidant in the light diffusion molded body is preferably 0.005 to 1.0 mass%, more preferably 0.01 to 0.5 mass%, based on the total mass of the light diffusion molded body. More preferably, it is 0.02 to 0.3% by mass.

In the light diffusion molded article, the transparent resin binder and the light diffusion particles are preferably contained in an amount of 60% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more.

[Manufacture of light diffusion moldings]
The light diffusion molded body is manufactured by blending the above-described transparent resin binder and material substances such as light diffusion particles. For example, each component such as a transparent resin binder is mixed using a tumbler and further melt-kneaded by an extruder to produce a pellet-shaped resin composition as a material for the transparent resin binder. Here, the form of the resin composition is not limited to a pellet form, and may be a flake form, a powder form, a bulk form, or the like.
Furthermore, a light diffusion molded body is obtained by molding the resin composition into a predetermined shape. For example, the light-diffusion molded object as a film for transparent screens can be manufactured by the process of processing a resin composition into a film or a sheet form.

[Transparent screen film]
The film for transparent screens of this invention contains the above-mentioned light diffusion molded object. More specifically, the transparent screen film of the present invention is formed mainly by a light diffusion molded body, and preferably only by a light diffusion molded body.
Thus, for example, the thickness of the light diffusion molded article utilized as a transparent screen film is preferably 10 μm to 3000 μm (0.01 mm to 3 mm), more preferably 30 μm to 2000 μm, and particularly preferably. Is 50 μm to 1000 μm.

As is clear from the fact that the transparent screen film contains the above-mentioned light diffusion molded article, the transparent screen film also contains a transparent resin binder and light diffusion particles.
The light diffusing particles contained in the transparent screen film preferably have a Z average particle diameter of 150 nm to 3500 nm, and the Z average particle diameter is more preferably 180 nm to 3000 nm, still more preferably 200 nm to 2000 nm. .
Thus, the solvent for dissolving the transparent screen film to confirm the value of the Z average particle diameter of the light diffusing particles is not particularly limited as long as the transparent screen film can be dissolved, but the above film is formed. Solvents with high solubility of the resin are preferred, and specific examples include dichloromethane, toluene, xylene, tetrahydrofuran, 1,4-dioxane, dimethylformamide, N-methylpyrrolidone, ethyl acetate, cyclohexanone, acetone, methyl ethyl ketone, methanol, cyclohexane, and the like. Of these, dichloromethane (CH ₂ Cl ₂ ) is preferred.

In order to grasp the actual distribution of the light diffusion particles in the transparent screen film, which is a light diffusion molded product, more accurately, the light diffusion in the state of being dispersed in the transparent screen film is observed by observing the cross section of the transparent screen film. It is preferable to measure the particle diameter of the particles and calculate the average particle diameter, for example.
That is, the particle diameter of the light diffusing particles contained in the transparent screen film is measured from the film image by a method described in detail later, and the value of the number average particle diameter is calculated from the obtained particle diameter data.

The number average value of the particle diameters of the light diffusing particles contained in the light diffusing molded article thus calculated is preferably 100 to 2300 nm, more preferably 150 to 2000 nm, and more preferably 180 to 1800 nm. More preferably, it is 200 to 1500 nm.
Further, regarding the particle size distribution of the light diffusing particles in the transparent screen film, the light diffusing particles having a number average particle size in the range of 300 to 2000 nm are 15% of the total number of the light diffusing particles as a reference. It is preferable to occupy the above, more preferably 20% or more, still more preferably 40% or more, particularly preferably 60% or more.

In addition, about the component of the light-diffusion particle | grains in the film for transparent screens, it is as having described in the column of the said <light-diffusion particle>, for example, from the group which consists of Bi, Nd, Si, Al, Zr, and Ti. It is preferable that any one or more of at least one selected element oxide, composite oxide, and a mixture of at least one of the oxide and the composite oxide is included. The light diffusing particles in the transparent screen film are more preferably at least one selected from bismuth oxide, zirconium oxide, silica, titania (titanium oxide) and alumina, and particularly preferably an oxide of bismuth and a composite oxide. And a mixture of at least one of the oxide and the composite oxide.

When the above-mentioned light diffusion particles are used, it is possible to maintain good color reproducibility while maintaining a wide viewing angle of the transparent screen. That is, in the conventional transparent screen, generally, the particle diameter of the light diffusing particles has been reduced to improve the diffusivity and widen the viewing angle. There has been a problem of color reproducibility such as an excess of. On the other hand, when the above-mentioned types of light diffusing particles are used, it is possible to realize good color reproducibility while widening the viewing angle.
In addition, the component of the light-diffusion particle | grains in the film for transparent screens can be confirmed by an energy dispersive X-ray (EDX) analysis, for example.

Further, the content of the light diffusing particles in the transparent screen film is the same as the content in the above-mentioned light diffusing molded article. That is, the transparent screen film preferably contains 0.001 to 3.0 parts by mass (about 0.001 to about 3.0% by mass) of light diffusing particles with respect to 100 parts by mass of the transparent resin binder. More preferably, the transparent screen film contains 0.01 to 1 part by weight of light diffusing particles with respect to 100 parts by weight of the transparent resin binder, and more preferably light diffusing with respect to 100 parts by weight of the transparent resin binder. The particles are contained in an amount of 0.03 to 0.5 parts by mass, and particularly preferably 0.1 to 0.3 parts by mass of the light diffusing particles with respect to 100 parts by mass of the transparent resin binder.

For example, in a light diffusion molded article that is a film for a transparent screen, the value of the total light transmittance is preferably 70% or more, more preferably 75% or more, and particularly preferably 80% or more. As described above, the transparent screen film having a high total light transmittance value has high transparency, and thus has excellent back view visibility in a state where no image is projected from the projector. The value of the total light transmittance in this specification is a value based on JIS-K-7361 and JIS-K-7136 described later.

For example, in a light diffusion molded body that is a film for a transparent screen, the haze value is preferably 80% or less, the haze value is more preferably 75% or less, still more preferably 72% or less, and particularly preferably. Is 45% or less, for example 20% or less. As described above, the transparent screen film having a sufficiently low haze value has high transparency, is excellent in aesthetics, and can display an image well. The haze value in the present specification is a value based on JIS-K-7361 and JIS-K-7136 described later.

For example, in a light diffusion molded body that is a film for a transparent screen, the value of diffusion degree D defined by the following formula (1) is 20 or more. Thus, in the transparent screen film formed by the light diffusion molded body having a large diffusion degree D, the effect of diffusing the transmitted light incident (projected) on the surface of the film can be obtained. Visibility is improved.
The value of the diffusivity D is preferably 22 or more, more preferably 24 or more, and particularly preferably 30 or more. Further, the value of the diffusivity D is preferably 80 or less, for example, 75 or less.

In the above formula (1), D is a diffusivity, and each value of I ₅ , I ₂₀ , and I _{70 is} a value of relative transmitted light intensity measured as follows.

A planar sample of the light diffusion molded body is arranged at a predetermined position (hereinafter referred to as a reference position), and the perpendicular and the planar sample are along an incident axis inclined by 10 ° with respect to a perpendicular perpendicular to the planar sample arranged at the reference position. Is the value of the relative transmitted light intensity of the transmitted light that has been transmitted through the flat sample, measured when the incident light is irradiated toward the intersection with.
More specifically, as described above, when incident light having a constant intensity is incident on an intersection (intersection between the virtual perpendicular and the surface of the planar sample of the light diffusion molded body), a virtual including the perpendicular is included. A plane that is perpendicular to the plane sample placed at the reference position and that is also perpendicular to the plane including the normal and the incident axis (hereinafter referred to as a vertical plane). The relative transmitted light intensity values of the transmitted light at the observation points where the angles θ to the perpendicular are 5 °, 20 °, and 70 ° and the distances from the intersections are equal to each other are expressed as I ₅ , I ₂₀ , and It is shown as I _70.

As described above, in order to calculate the diffusivity D, the planar sample is irradiated with incident light from a direction inclined by 10 ° with respect to a perpendicular perpendicular to the planar sample of the light diffusion molded body. The state in which the sample is arranged so that the optical axis of the incident light is tilted by 10 ° with respect to the perpendicular perpendicular to the plane sample is a diagram showing an example of a measuring device for measuring the transmitted light distribution of the light diffusion molded body. It is indicated by 1.
In this way, when incident light is incident from a direction inclined with respect to the normal of the light receiving surface without entering incident light perpendicular to the light receiving surface of the flat sample, the optical axis of the incident light and a plurality of observation points And a virtual vertical plane including For this reason, it becomes possible to suppress the intensity | strength of transmitted light to a certain level, and the measurement of the value of the relative transmitted light intensity of transmitted light, and an intensity ratio becomes easy.
That is, the relative intensity of transmitted light can be accurately measured by tilting the optical axis of incident light by 10 ° with respect to a perpendicular perpendicular to the plane sample.

In addition, as shown in FIG. 2, by making the light receiving portion rotatable, the angle θ with respect to the perpendicular is on various observation points on the virtual vertical plane perpendicular to the flat sample as described above. The light receiving unit can be moved. For example, in the transmitted light distribution measuring apparatus illustrated in FIG. 2, the light receiving unit can be rotated from + 90 ° to −90 °, so that the light receiving unit is 5 °, 20 °, And can be easily moved to a position of 70 °, so that the values of I ₅ , I ₂₀ , and I ₇₀ can be measured. The rotational positions of 5 °, 20 °, and 70 ° may be rotational positions on either the + side or the − side illustrated in FIG.
The intensity of the incident light, the thickness of the flat sample, and the distance from the intersection to the observation point are values of I ₅ , I ₂₀ , and I ₇₀ indicating the relative transmitted light intensity of the transmitted light. Since it does not give a change, it can be set appropriately.

As described above, when the incident light is irradiated onto the intersection along the incident axis inclined by 10 ° with respect to the normal, the transmission of the reference transmitted light that passes through the plane sample at the reference position and proceeds along the vertical is transmitted. An angle θ ₁ with respect to a perpendicular of a line passing through an observation point on a vertical plane where transmitted light having a relative transmitted light intensity ½ of the light intensity is observed and an intersection point is 10.8 ° or more. preferable.
In addition, as described above, when the incident light is irradiated to the intersection along the incident axis inclined by 10 ° with respect to the normal, the reference transmission that passes through the plane sample arranged at the reference position and proceeds along the normal is performed. an observation point on the vertical plane transmitted light with a relative intensity of transmitted light 1/10 with respect to the transmission light intensity of the light is observed, the angle theta ₂ is at 30 ° or more with respect to the perpendicular line passing through the intersection point Is preferred.
When a light diffusion molded body that satisfies these requirements is used for a transparent screen, the viewing angle can be particularly widened.

In the light diffusion molded body, when the planar sample is disposed at a predetermined reference position, when the incident light is irradiated along the normal of the planar sample, the light diffused in a direction that forms an angle of 45 ° with respect to the planar sample. It is preferable that the values of a * and b * expressed in the CIE 1976 color space calculated from the spectrum of light by a method according to JIS-Z-8781-4 satisfy the following conditions. That is,
(I) The value of a * is −5 or more and 5 or less,
(Ii) The value of b * is preferably −15 or more and 15 or less.
The value of a * is more preferably from −4 to 4 and even more preferably from −3 to 3.
Further, the value of b * is more preferably −10 or more and 10 or less, and further preferably −5 or more and 5 or less.
When the light diffusion molded body satisfying the above conditions (i) and (ii) is used for the transparent screen, the color balance of the visually recognized image is improved and high color reproducibility is realized.

In the light diffusion molded body, it is calculated by a method based on JIS-Z-8781-4 from the spectrum of transmitted light that diffuses in a direction that forms an angle of 45 ° with respect to a flat sample, measured under the above conditions. It is preferable that the value of the saturation C * expressed in the CIE 1976 color space further satisfies the following condition (iii). That is,
(Iii) C * is preferably from −10 to 10 and more preferably from −5 to 5.

For example, in a light diffusion molded body that is a film for a transparent screen, the diffusivities when the wavelengths of irradiation light to be irradiated are 400 nm, 500 nm, 600 nm, and 700 nm are B (400), B (500), and B ( 600) and B (700), the relative standard deviation of B (400), B (500), B (600), and B (700) (hereinafter also simply referred to as relative standard deviation) is 0 to 20 % Is preferable. More preferably, the value of the relative standard deviation of B (400), B (500), B (600), and B (700) is 18% or less, and particularly preferably 15% or less.

In this way, when light of different wavelengths is incident (irradiated), a transparent screen film having a sufficiently small difference in diffusivity value according to the wavelength range provides a good balance of various colors in the projected image. Color reproducibility is improved.

Moreover, it is preferable that the YI value ((DELTA) YI value based on JISZ8722) of the film for transparent screens is 5 or less. More preferably, the YI value (ΔYI value) of the transparent screen film is 4.2 or less, and particularly preferably 3.0 or less.
As described above, in the transparent screen film having a small YI value (ΔYI value), the color change that can be caused by the decomposition of the resin of the material, in particular, the color change to yellow is suppressed. For this reason, in a transparent screen film having a small YI value (ΔYI value), the color reproducibility can be further improved.

The transparent screen film of the present invention is suitably used for the production of a transparent screen. In addition, “transparent” described in the specification of the present application means that the image has a transparency that can be projected on a screen and can achieve a certain degree of transmission visibility. The transparent screen produced by the transparent screen film of the present invention has not only a feature of wide viewing angle and excellent color reproducibility but also a feature of high transparency and visible light transmittance.

In the transparent screen, layers other than the transparent screen film of the present invention may be laminated. For example, a support layer for supporting the transparent screen film, a protective layer for protecting the surface of the transparent screen film, and an adhesive layer for adhering other layers to the transparent screen film may be laminated. good.
The adhesive layer of the transparent screen is, for example, a layer for attaching a film to the transparent screen, and the adhesive layer is preferably formed using an adhesive composition. Examples of the pressure-sensitive adhesive composition include natural rubber-based, synthetic rubber-based, acrylic resin-based, polyvinyl ether resin-based, urethane resin-based, and silicone resin-based so as not to impair the optical characteristics and transparency of the transparent screen film. Etc. are preferably used. Specific examples of the synthetic rubber-based pressure-sensitive adhesive composition include styrene-butadiene rubber, acrylonitrile-butadiene rubber, polyisobutylene rubber, isobutylene-isoprene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, styrene. -Ethylene-butylene block copolymer. Specific examples of the silicone resin-based pressure-sensitive adhesive composition include dimethylpolysiloxane. These components can be used alone or in combination of two or more. Among these, it is preferable to form the adhesive layer using a silicone adhesive, an acrylic adhesive, or the like.

The thickness of the transparent screen is, for example, 0.45 mm to 2 mm, more preferably 0.48 mm to 1.5 mm, and particularly preferably 0.5 mm (500 μm) to 1.0 mm.

In addition, about the shape of the film for transparent screens of this invention, any of a plane and a curved surface may be sufficient, and what was processed two-dimensionally or three-dimensionally may be sufficient. The processing method is not particularly limited, but preferred examples include a thermal processing method, a punching method, a cold bending method, a drawing method, and the like, such as a hot bending method, a curved surface processing method, and a free processing method. A blow molding method and the like are more preferable, and a press molding method, a vacuum molding method, a compressed air molding method, a natural standing method, and the like are particularly preferable.

[Projection of image]
In the projection of an image, a transparent screen manufactured by the transparent screen film of the present invention can be used. In video projection, the image may be projected from the back of the transparent screen or from the front. That is, the transparent screen may be a transmissive screen for observing transmitted light or a reflective screen for observing reflected light.

[Method for producing film for transparent screen]
The transparent screen film of the present invention is produced using a light diffusion molded article as described above. For example, a predetermined amount of light diffusing particles is added to the light diffusing molded body and melt kneaded. And the pellet of the light-diffusion molded object containing a light-diffusion particle is obtained by strand cutting, for example. The transparent screen film can be produced by extruding the thus obtained light diffusion molded article pellets with, for example, a film extruder.

Furthermore, the shape of the transparent screen film is adjusted by appropriately selecting and employing the various processing methods described above. Thus, the transparent screen film whose shape is appropriately adjusted is used for the production of a transparent screen. More specific production methods include the methods of the following examples.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the following examples.

The raw materials used in Examples and Comparative Examples are as follows.
[material]
・ Thermoplastic resin (A) (transparent resin binder)
(A1) Aromatic polycarbonate resin obtained by an interfacial polymerization method using bisphenol A as a starting material (Iupilon S-3000F manufactured by Mitsubishi Engineering Plastics Co., Ltd., viscosity average molecular weight: 22,000)
(A2) Modified polyethylene terephthalate resin (SKYGREEN S2008, SK Chemicals, viscosity average molecular weight: 31,000)

・ Light diffusion particles (B) (inorganic particles)
(B1) Bismuth metal oxide (bismuth oxide containing neodymium oxide, 42-920A manufactured by Toago Material Technology Co., Ltd.)
(B2) Particles obtained by crushing and classifying bismuth metal oxide (bismuth oxide containing neodymium oxide, 42-920A manufactured by Toago Material Technology Co., Ltd.) Model: Super jet mill SJ-500) and air classifier manufactured by Nissin Engineering Co., Ltd. (model: Aerofine Classia AC-20). The processed particles were obtained by removing coarse particles. The obtained particles were dispersed in pure water, and the particle size distribution was measured using a particle size distribution measuring apparatus using a laser diffraction scattering method (MT3300EXII manufactured by Microtrack Bell Co., Ltd.). As a result, D50 of B1 particles before processing was 0.94 μm, and B2 particles after processing was 0.27 μm.
(B3) Particles in which bismuth-based metal oxide (bismuth oxide containing neodymium oxide, 42-920A manufactured by Toago Material Technology Co., Ltd.) is made into nanoparticles by plasma processing. Nanoparticles were obtained by evaporating and aggregating particles with thermal plasma generated in a high-frequency magnetic field, using a nanoparticle processing system. The specific surface area of the obtained particles was measured using a specific surface area measuring apparatus using the BET method (Macsorb HM model-1208 manufactured by Mountec Co., Ltd.). The BET specific surface area of the B1 particles before processing was was 1.8m ² / g, B3 particles after processing was 15.5 m ² / g.
(B4) Silica particles (Silicon dioxide, Admanano YA050C-SP3 manufactured by Admatechs Co., Ltd.)
(B5) Silica particles (silicon dioxide, Admafine SO-C1 manufactured by Admatechs Co., Ltd.)
(B6) Silica particles (silicon dioxide, Admafine SC-2500SQ manufactured by Admatechs Co., Ltd.)
(B7) Silica particles (silicon dioxide, Admafine SC-C6 manufactured by Admatechs Co., Ltd.)
(B8) Alumina particles (aluminum oxide, Admafine AO-502 manufactured by Admatechs Co., Ltd.)
(B9) Zirconia particles (zirconium oxide, Zirconia methanol dispersion SZR-M particle concentration 30.5 wt%, manufactured by Sakai Chemical Industry Co., Ltd.)
(B10) Zirconia particles (zirconium oxide, UEP manufactured by Daiichi Rare Element Chemical Industries, Ltd.)
(B11) Zirconia particles (zirconium oxide, SPZ manufactured by Daiichi Rare Element Chemical Industries, Ltd.)
(B12) Titania particles (titanium oxide, TITANIX JR-405 manufactured by Teika Co., Ltd.)
(B13) Titania particles (titanium oxide, TITANIX JR-301 manufactured by Teika Co., Ltd.)

・ Antioxidant (C)
Bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite (phosphorus-based antioxidant, stopper ADEKA STAB PEP-36)
Mold release agent (D) Glycerol monostearate (Rikenmar S-100A manufactured by Riken Vitamin Co., Ltd.)

[Measurement of Z average particle diameter and polydispersity index (Pdi) of light diffusion particles contained in resin composition]
The Z average particle diameter and polydispersity index (Pdi) of the light diffusing particles (B) are determined by cumulant analysis from the measurement results using the Malvern Zetasizer Nano ZS measuring device using the dynamic light scattering method. It was. The measurement was performed at room temperature, and a dispersion liquid in which the light diffusing particles (B) were dispersed in pure water at a concentration of 0.1% by weight was measured. Note that ultrasonic waves were used for dispersion of the light diffusing particles (B).
The polydispersity index (PDi) is an index that defines the particle size distribution of particles. The narrower the particle size distribution is, the closer PDi approaches to zero. Conversely, the particle size distribution is wide, that is, the polydispersity is large. As PDi increases.

[Production of thermoplastic resin pellets with added light diffusion particles]
With respect to the thermoplastic resins (A1) and (A2) described above, the light diffusing particles (B), the antioxidant (C), and other additives (D) are added in the amounts shown in Table 2, respectively. Added. Then, after mixing resin etc. for 20 minutes with a tumbler, melt-kneaded at a cylinder temperature of 280 ° C. with a twin screw extruder with a screw diameter of 26 mm (“TEM26SS” manufactured by Toshiba Machine Co., Ltd.), and strand cutting To obtain a pellet.

[Production of thermoplastic resin film to which light diffusion particles are added]
The obtained pellets are melted and extruded by a twin-screw film extruder with a T-die lip with a screw diameter of 30 mm (TEX-30α manufactured by Nippon Steel Co., Ltd.) to obtain a sheet and a film-like molded product. Produced.

[Production Example 1 of adhesive layer]
A thermosetting paint was applied to the resin film of Example 4 thus molded using a metal bar coater, and then heated and dried in an oven to form a primer layer having a thickness of 1 μm. Thereafter, a reverse gravure roll was used to apply a silicone-based adhesive paint, followed by heating and drying in an oven to form an adhesive layer having a thickness of 50 μm.

[Production Example 2 of adhesive layer]
In addition, an acrylic adhesive was applied to the release-treated surface of the 25 μm-thick PET film using a gravure roll or bar coater, and then heated and dried in an oven to a thickness of 17 μm. An adhesive film was formed. The adhesive layer of the adhesive film was bonded to the resin film of Example 4 and pressed to transfer the adhesive layer to the resin film of Example 4. When the adhesive layer-attached resin films of Production Examples 1 and 2 in which the adhesive layer was formed in this manner were attached to a glass plate having a thickness of 5 mm and visually observed, the film was very transparent. Furthermore, when an image was projected onto these resin films with an adhesive layer using an ultra-short focus projector (trade name: PJ WX4152 manufactured by Ricoh Co., Ltd.), it was confirmed that the visibility of the projected image was sufficiently high. It was.

The particle diameter of the light diffusing particles contained in the resin films of each Example and Comparative Example was measured by a method of observing the cross-sectional shape of the film (cross-sectional observation method).

[Measurement of particle size of light diffusion particles in resin film by cross-sectional observation (cross-sectional observation method)]
The resin film molded by the above-described method was subjected to cross-section processing by ion milling for about 3 hours, and the obtained cross-section was observed by a field emission scanning electron microscope (FE-SEM). The apparatus used for this ion milling cross-section processing is IM-4000 manufactured by Hitachi High-Technologies, and the apparatus used for cross-sectional observation by FE-SEM is SU-8220 manufactured by Hitachi High-Technologies. As an image observation mode for cross-sectional observation, an LA-BSE image was used, and the particle diameter of particles that could be observed when the magnification was 2000 times was measured. For each film, at least 10 or more particles were observed.

Based on the above observation data, the particle diameter d of each particle is
The calculation was made based on the formula (particle size in the long side direction (a) + particle size in the short side direction (b)) / 2 = d. The outline of the particle diameter (a) in the long side direction and the particle diameter (b) in the short side direction is as shown in FIG. 3, and the particle diameter (a) is the largest of the diameters passing through the center point of the cross section of the particle. The particle diameter (b) is the shortest particle diameter among the diameters passing through the center point of the cross section of the particle.
Further, the value of the average particle diameter of a large number of particles was used as the number average particle diameter Dav, and calculation was performed according to the following formula Σ (nd) / Σ (n) = Dav. In this formula, d represents the particle diameter of each particle, that is, each particle diameter, and n represents a number-based percentage. Further, the ratio of the number of particles having a particle diameter d in the range of 300 to 2000 nm to the total number of observable particles was determined.
Furthermore, by performing energy dispersive X-ray (EDX) analysis, it was confirmed that the observed particles were light diffusing particles that are targets for particle diameter calculation. The apparatus used for EDX is X-Max ^{N for} Horiba.

[Evaluation of optical properties of film]
The optical characteristics of the molded articles produced in the above examples and comparative examples were evaluated as follows.
First, the total light transmittance (%) and haze (%) of the molded product were measured using a haze meter (trade name: HM-150, manufactured by Murakami Color Research Laboratory Co., Ltd.) and JIS-K-7361 and The measurement was performed according to JIS-K-7136.
Next, the image clarity of the molded product was measured for the image clarity of the transmitted light of the molded product in accordance with JIS K7374 using an image clarity measuring machine (Model: ICM-1T manufactured by Suga Test Instruments Co., Ltd.) The image clarity (%) when measured with an optical comb width of 0.125 mm was defined as image clarity.

[Light diffusion of film]
<Measurement method of diffusivity D>
Using a goniophotometer (model GP-200) with a halogen lamp manufactured by Murakami Color Research Co., Ltd. as a light source and an optical axis detour device, the normal direction to the flat sample of the molded body under the following measurement conditions The relative transmitted light intensity distribution measured when the light was irradiated at a vertical angle of 10 ° was measured. Before measurement, sensitivity is checked in the light reception range of -1 ° to 1 °. If the peak intensity exceeds 100%, a neutral density filter is inserted as appropriate, and the maximum intensity does not exceed 100%. It was made to become. The characteristics of the neutral density filter used are as follows.

The diffusivity D was calculated by the following formula (1) using the obtained data of the relative transmitted light intensity distribution. Further, by using the distribution curve data of the mountain shape of the relative transmitted light intensity distribution, the emission angle (1/2 half width) corresponding to 1/2 the peak intensity of the peak and 1/10 the peak intensity of the peak The emission angle (1/10 value half width) corresponding to is calculated.

(In the above formula (1), Iθ (I ₅ , I ₂₀ , and I ₇₀ ) is a value obtained when incident light having a constant intensity is incident on the intersection of the optical axis of the incident light and the flat sample of the molded body. Observation points that include a perpendicular line and are on a virtual vertical plane that is perpendicular to the plane sample, the angles θ with respect to the perpendicular line are 5 °, 20 °, and 70 °, respectively, and the distances from the intersection are equal to each other The value of the relative transmitted light intensity of the transmitted light is shown.)
・ Measurement conditions: Transmission ・ High Volt Adj: -900
Sensitivity Adj: 500
・ Flux diaphragm: 3.0
・ Light-receiving aperture: 4.0
-Incident angle: 0 °
・ Sample tilt angle: 0 °
・ Reception start angle: -90 °
・ Reception angle: 90 °
・ Measurement pitch: 0.1 ° interval

[Color of diffused light]
<Measuring method of a * value and b * value>
As schematically shown in FIG. 4, a variable angle spectrocolorimetry system GCMS-4B (measuring instrument model: GSP-2) using a halogen lamp manufactured by Murakami Color Research Co., Ltd. as a light source 10 and including a variable angle spectrophotometer 30. Of the transmitted light L ₂ at each light receiving angle measured when the incident light L ₁ is irradiated at 0 ° perpendicular to the normal direction to the planar sample 20 of the molded body under the following measurement conditions. Distribution measurements were made. The light receiving angle corresponds to the angle of the transmitted light L ₂ with respect to the optical axis of L ₁ of incident light.
Before the measurement, the sensitivity of the light source was adjusted under the condition that the opal glass was irradiated with light at 0 ° perpendicular to the normal direction and received transmitted light at 5 °. From the spectral distribution data of the transmitted light diffusing in a direction that forms an angle of 45 ° with respect to the horizontal direction from the normal direction of the molded body 20, that is, from the spectral distribution data when the light receiving angle is 45 °, JIS-Z-8781 -4, the a *, b *, saturation C *, and hue h * values expressed in the CIE 1976 color space were calculated.
・ Measurement conditions: Transmission ・ Light source: Standard Illuminant D65
-Field of view: 2 ° field of view-Incident angle: 0 °
・ Sample tilt angle: 0 °
・ Light reception start angle: 80 °
・ Reception end angle: 80 °
Measurement pitch: 5 ° interval Next, the transparency of the flat sample of the molded body was visually evaluated based on the following criteria.

[Transparency evaluation criteria]
Especially good: the film was very transparent.
Good: The film was transparent.
Slightly poor: The film was slightly cloudy and inferior in transparency.
Defect: The film was cloudy and poor in transparency.

[Production and evaluation of transparent screens]
As the transparent screen, the sheets and films produced in the above-mentioned Examples and Comparative Examples were placed at a position 12 cm away from the image projection lens of the ultra-short focus projector (trade name: PJ WX4152 manufactured by Ricoh Co., Ltd.). Next, an image was projected onto the screen from below 60 °, and the focus knob of the projector was adjusted so that the position of the screen was in focus. Regarding the luminance uniformity of the projector image, the image visibility when observed from the front front, the image visibility when observed from 1 m ahead of 45 ° obliquely, and the color of the image are visually evaluated based on the following criteria. did. The image visibility was evaluated in a dark room by observing the opposite surface of the projector, that is, the screen transmitted light. The evaluation results are shown in Table 3 below.

[Evaluation criteria for uniformity of image brightness]
Particularly good: The brightness was very uniform no matter what direction the screen image was viewed.
Good: The brightness was uniform no matter what direction the screen image was viewed.
Defect: The brightness was different and non-uniform depending on the viewing angle of the screen image.
[Evaluation criteria for image color]
Particularly good: The color reproducibility of the screen image was very high.
Good: The color reproducibility of the screen image was high.
Slightly poor: Screen image was bluish and color reproducibility was slightly low.
Defect: The screen image is very blue and the color reproducibility is low.

Claims

A light diffusion molded article containing a transparent resin binder and light diffusion particles,
A plane sample of the light diffusion molded body is arranged at a reference position,
Measured when irradiating incident light toward an intersection of the perpendicular and the planar sample along an incident axis inclined by 10 ° with respect to a perpendicular perpendicular to the planar sample arranged at the reference position, A light diffusion molded article in which the value of the diffusivity D defined by the following formula (1) is 20 or more from the value of the relative transmitted light intensity of the transmitted light transmitted through the planar sample.

(However, in the above formula (1),
D is the diffusivity,
I 5 , I 20 , and I 70 are planes that are perpendicular to the planar sample that includes the perpendicular and is at the reference position when the incident light having a constant intensity is incident on the intersection. The angle θ with respect to the perpendicular is 5 °, 20 °, and 70 °, respectively, and is on the virtual vertical plane perpendicular to the plane including the normal and the incident axis, and from the intersection The relative transmitted light intensity values of the transmitted light at observation points where the distances are equal to each other are shown. )
From the spectral spectrum of transmitted light that diffuses in a direction that forms an angle of 45 ° with respect to the planar sample when the planar sample disposed at the reference position is irradiated with incident light along the perpendicular line, JIS- The value of a * and b * expressed in the CIE 1976 color space calculated by a method based on Z-8771-4 satisfies the following conditions (i) and (ii): Light diffusion molded product.
(I) The value of a * is −5 or more and 5 or less.
(Ii) The value of b * is −15 or more and 15 or less.
3. The value of saturation C * expressed in the CIE 1976 color space calculated from a spectrum of the transmitted light by a method according to JIS-Z-8781-4 further satisfies the following condition (iii): The light-diffusion molded object of description.
(Iii) C * is −10 or more and 10 or less.
When the incident light is irradiated along the incident axis with respect to the intersection, the transmitted light intensity of the reference transmitted light that passes through the planar sample arranged at the reference position and travels along the perpendicular line an observation point on the vertical plane transmitted light with a relative intensity of transmitted light 1/2 is observed, the angle theta 1 is 10.8 ° or more with respect to the perpendicular line passing through said intersection, claim 1 4. The light diffusion molded article according to any one of items 1 to 3.
When the incident light is irradiated along the incident axis with respect to the intersection, the transmitted light intensity of the reference transmitted light that passes through the planar sample arranged at the reference position and travels along the perpendicular line an observation point on the vertical plane transmitted light with a relative intensity of transmitted light 1/10 is observed, the angle theta 2 is at 30 ° or more with respect to the perpendicular line passing through said intersection, claims 1 to 3, The light-diffusion molded object as described in any one of these.
The light diffusion molded article according to any one of claims 1 to 5, wherein the value of the diffusivity D is 80 or less.
The light diffusion particle is an oxide of at least one element selected from the group consisting of Bi, Nd, Si, Al, Zr, and Ti, a composite oxide, and at least the oxide and the composite oxide The light diffusion molded article according to any one of claims 1 to 6, comprising any one or more of any mixture.
The light diffusing particle according to claim 7, wherein the light diffusing particles include at least one of a Bi oxide, a composite oxide, and a mixture of at least one of the oxide and the composite oxide. Molded body.
The light diffusion molded article according to any one of claims 1 to 8, wherein the light diffusion particles have a Z average particle diameter of 150 to 3500 nm.
The light diffusion molded article according to any one of claims 1 to 9, wherein a value of a number average particle diameter of the light diffusion particles contained in the light diffusion molded article is 100 to 2300 nm.
The particle diameter of the light diffusing particles of 15% or more based on the number of the light diffusing particles contained in the light diffusing molded body is in the range of 300 to 2000 nm. The light-diffusion molded object of description.
The light diffusion molded article according to any one of claims 1 to 11, wherein 0.001 to 3 parts by mass of the light diffusion particles are contained with respect to 100 parts by mass of the transparent resin binder.
The light diffusion molded article according to any one of claims 1 to 12, wherein a polydispersity index of the light diffusion particles is 0.8 or less.
The light diffusion molded article according to any one of claims 1 to 13, wherein the transparent resin binder contains a thermoplastic resin.
The light diffusion molded body according to claim 14, wherein the thermoplastic resin includes a polycarbonate resin.
A transparent screen film comprising the light diffusion molded article according to any one of claims 1 to 15.