WO2019208770A1

WO2019208770A1 - Light-diffusing molded body, film for transparent screen, and method for evaluating light-diffusing molded body

Info

Publication number: WO2019208770A1
Application number: PCT/JP2019/017943
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: JPWO2019208770A1; CN112055823A; CN112055823B

Abstract

Provided is a light-diffusing molded body, etc., having excellent viewing angle characteristics and excellent color reproduction properties in particular. The above problem is solved by a light-diffusing molded body including a transparent resin binder and light-diffusing particles, wherein, when incident light is radiated to the intersection point of a plane sample of the light-diffusing molded body disposed in a reference position and a perpendicular line which is perpendicular to the plane sample and is along an incidence axis inclined 5° with respect to the perpendicular line, in a relative reflected light intensity distribution of reflected light reflected along a reflected light plane which is a plane which includes the perpendicular line and is perpendicular to the plane sample, and in which a perpendicular plane perpendicular also to a plane including the perpendicular line and the incidence axis is inclined 5° to the opposite side from the incidence axis, the value of the inclination angle between a reference optical axis of regularly reflected light as reflected light proceeding along the line intersection of a reflected light plane and a plane including the perpendicular line and the incidence axis, and the optical axis of reflected light having a relative reflected light intensity of 50% of the intensity of the regularly reflected light, is 18° or greater.

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 article including a 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, if a light diffusion molded body in which reflected light or transmitted light is not sufficiently diffused is used for a transparent screen, the viewing angle is narrowed, and an image on the transparent screen can be viewed from a position away from the front of the transparent screen. There was a problem that became difficult.

In addition, in a video projected on a transparent screen based on a 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 resin composition, and the like shown below.
In the present specification, the film includes, for example, a sheet having a thickness of 1 mm or more.

(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,
When the incident light is irradiated toward the intersection of the perpendicular and the planar sample along an incident axis inclined by 5 ° with respect to a perpendicular perpendicular to the planar sample arranged at the reference position, the perpendicular is A plane that is perpendicular to the plane sample and that is also perpendicular to the plane that includes the normal and the incident axis, and is inclined by 5 ° to the opposite side of the incident axis. In the relative reflected light intensity distribution of the reflected light reflected along a certain reflected light plane,
Reference light of specularly reflected light, which is reflected light that is reflected along the intersection of the plane that includes the normal and the incident axis, and the reflected light plane is reflected by the incident light that is incident along the incident axis. A light diffusion molded article, wherein a value of an inclination angle that is an angle between an axis and an optical axis of reflected light having a relative reflected light intensity of 50% of the intensity of the regular reflected light is 18 ° or more.
(2) When incident light is incident on the planar sample arranged at the reference position at an angle of 45 ° with respect to the perpendicular, the optical axis of the incident light is opposite to the perpendicular. The values of a * and b * expressed in the CIE 1976 color space calculated by the method according to JIS-Z-8781-4 from the spectrum of diffusely reflected light that is diffused while reflecting in the direction are as follows: The light diffusion molded article according to (1), which satisfies (i) and (ii).
(I) The value of a * is −5 or more and 5 or less.
(Ii) The value of b * is −10 or more and 10 or less.
(3) The value of the saturation C * expressed in the CIE 1976 color space calculated from the spectrum of the diffusely reflected light by a method based on JIS-Z-8781-4 further satisfies the following condition (iii) The light diffusion molded article according to (2) above.
(Iii) C * is −10 or more and 10 or less.
(4) A value of an inclination angle of the optical axis of the reflected light having a relative reflected light intensity of 10% of the intensity of the regular reflected light with respect to the reference optical axis is 70 ° or more. The light-diffusion molded object as described in any one of these.
(5) The value of the inclination angle of the optical axis of the reflected light having a relative reflected light intensity of 50% of the intensity of the regular reflected light with respect to the reference optical axis is 18 ° or more and 70 ° or less (1) The light diffusion molded article according to any one of (4) to (4).
(6) 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 (5), comprising any one or more of at least any mixture of the above substances.
(7) The light diffusion molded article according to (6), wherein the light diffusion particles include at least a Bi oxide, a composite oxide, and a mixture of at least one of the oxide and the composite oxide.
(8) The light diffusion molded article according to any one of (1) to (7), wherein the light diffusion particles have a Z average particle diameter of 100 to 3000 nm.
(9) The light diffusion molded article according to any one of (1) to (8), wherein the number average particle diameter of the light diffusion particles contained in the light diffusion molded article is 100 to 2000 nm.
(10) The above (1) to (9), wherein a 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 a range of 300 to 2000 nm. The light-diffusion molded object as described in any one of these.
(11) The light diffusion molded article according to any one of (1) to (10), 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.
(12) The light diffusion molded article according to any one of (1) to (11), wherein the polydispersity index of the light diffusion particles is 0.8 or less.
(13) The light diffusion molded article according to any one of (1) to (12), wherein the transparent resin binder contains a thermoplastic resin.
(14) The light diffusion molded article according to (13), wherein the thermoplastic resin contains a polycarbonate resin.
(15) A transparent screen film comprising the light diffusion molded product according to any one of (1) to (14) 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 reflected 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 reflected light distribution of a light-diffusion molded object. It is a top view which shows an example of the measuring apparatus for measuring the reflected light distribution of a light-diffusion molded object. A regular reflection light that is a reflection light that travels along the horizontal optical axis L ₁ (reference optical axis) and is generated by irradiating incident light onto the reflection surface of the flat sample 20 and a predetermined angle α from the reference optical axis. It is a figure which illustrates the (diffuse) reflected light which progresses away. It is a figure which shows roughly the measuring method of the intensity | strength of the diffuse reflected light which arises when incident light injects at an angle of 45 degrees with respect to the perpendicular of a plane sample. 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 graph which shows the spectrum (relative reflected light intensity | strength) of the light ray of the reflected light from a light-diffusion molded object in 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 light diffusion film such as a transparent screen film because it can diffuse reflected light of incident light over a wide range and has high viewing angle characteristics. That is, even when the reflected light generated when light enters the light diffusion molded body travels in a direction away from the optical axis of the incident light, it 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 the viewing angle characteristic, 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 range, high transparency of the light diffusing molded body is ensured, a sufficient scattering effect of the reflected light of the projected light is obtained, and color reproducibility and the like are obtained. The visibility of the image is also improved.

<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 point that it is easy to obtain one with a small amount of impurities contained therein, an aromatic polycarbonate is more preferable. It is done. Examples of the aromatic polycarbonate include those having a bisphenol A skeleton.

Although there is no restriction | limiting in the specific kind of polycarbonate resin, For example, the polycarbonate polymer formed by making a dihydroxy compound and a carbonate precursor react is mentioned. 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 100 nm to 3000 nm. The Z average particle diameter of the light diffusing particles is more preferably 140 nm to 2500 nm, and further preferably 200 nm to 1500 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, it is possible to realize a transparent screen excellent in light diffusibility of reflected light and color reproducibility.
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 diffusing particles are preferably contained in total of 60% by mass or more, more preferably 80% by mass or more, based on the total mass of the light diffusion molded product. Particularly preferably 90% by mass or more is contained.

[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 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 (0.001 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 100 nm to 3000 nm, and the Z average particle diameter is more preferably 140 nm to 2500 nm, still more preferably 200 nm to 1500 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 2000 nm, more preferably 150 to 1800 nm, and preferably 200 to 1500 nm. Further preferred.
In addition, regarding the particle size distribution of the light diffusing particles in the transparent screen film, the light diffusing particles having a particle size in the range of 300 to 2000 nm account for 15% or more based on the total number of the light diffusing particles. It is preferable to occupy, 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 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. 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, the light diffusing particles with respect to 100 parts by weight of the transparent resin binder. 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.

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 can clearly display the image 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 which is a film for a transparent screen, as described in detail below, in the intensity distribution of reflected light measured when irradiated with incident light, a reflection angle equal to the incident angle of incident light is obtained. The light traveling while being diffusely reflected in the direction away from the optical axis of the reflected light also has a certain intensity or more. As described above, the intensity of light that is diffused and reflected does not greatly decrease compared to the intensity of reflected light having a reflection angle equal to the incident angle. Therefore, the transparent screen film formed by the light diffusion molded article of the present invention. As described below, the effect of diffusing reflected light of light incident (projected) on the surface of the film is obtained, and the visibility of the image is improved.

First, a planar sample of the light diffusion molded body is arranged at a predetermined reference position, not along the perpendicular direction to the planar sample arranged at the reference position, but along the incident axis inclined by 5 ° with respect to the perpendicular. Incident light is irradiated toward the intersection of the perpendicular and the flat sample, and the relative reflected light intensity distribution of the reflected light is measured. For example, in FIG. 1, the light source unit 10 irradiates incident light along an incident optical axis L ₂ that is inclined by 10 ° with respect to the horizontal optical axis L ₁ . Plane sample 20 on the sample stage is 5 for because it is fixed to the reference position so that the 5 ° upwards relative to the horizontal optical axis L _1, the incident light, the reflecting surface of the plane sample of the reference position Irradiated from a tilted direction.

Then, the reflected light having a reflection angle equal to the incident angle, that is, a reflection angle of 5 ° in this case, travels along the horizontal optical axis L ₁ , and the intensity is measured by the light receiving unit 30. In FIG. 1, the light receiving unit 30 is not located at the light receiving position, and moves to the light receiving position when measuring reflected light. However, the light receiving unit 30 has an equal angle of incidence and the angle of reflection as described above, not only the reflected light travels along a horizontal optical axis L _1, while diffuse reflection away from the horizontal optical axis L ₁ The intensity of the reflected light traveling can also be measured.

In other words, the light receiving unit 30 is movable in the circumferential direction around the center of the flat sample 20 placed at the reference position, and as illustrated by the arrow A in FIG. 2, from the horizontal optical axis L _1. It is also possible to measure the intensity of light traveling along a remote optical axis.

Using a measuring device as described above, in this embodiment, with respect to the vertical line perpendicular to the surface of the flat sample at the reference position (for example, an intermediate line between the horizontal optical axis L ₁ and the incident optical axis L ₂ in FIG. 1) In the illustration of FIG. 1, the incident light is irradiated to the intersection of the normal and the plane sample along an incident axis inclined at an angle of 5 ° (for example, the incident optical axis L ₂ in FIG. 1). Is a reflected light plane (a plane inclined at an angle of 5 ° to the opposite side of the incident axis (for example, incident optical axis L ₂ ) with a plane coinciding with the intermediate line between the horizontal optical axis L ₁ and the incident optical axis L _2. for example, the reflection to proceed along a plane) coincides with the horizontal optical axis L ₁ in FIG. 1 (diffuse reflection) by the relative reflected light intensity distribution of the reflected light is measured.

Note here, the plane coincides with a mid-line between the horizontal optical axis L ₁ and the incident optical axis L ₂ in the illustrated a plan Figure 1 including perpendicular also to the surface of the planar samples in the reference position It is also perpendicular to a plane (a plane parallel to the paper surface of FIG. 1) including the normal and the incident axis.

In this way the measured relative reflected light intensity distribution occurs in incident light reflected incident along the axis of incidence, which is illustrated as incident optical axis L ₂ in FIG. 1, the reflection angle of 5 ° is equal to the angle of incidence The intensity of diffusely reflected light that travels at a predetermined angle in the horizontal direction from the optical axis of the reflected light (for example, horizontal optical axis L _{1 in} FIG. 1: reference optical axis of regular reflected light) is also measured. For example, as illustrated in FIG. 3, when incident light is irradiated to P that is a point on the reflecting surface of the planar sample 20 and is an intersection with the perpendicular, the horizontal optical axis L ₁ (reference) The intensity of specularly reflected light that travels along the optical axis) and the intensity of (diffused) reflected light that travels away from the reference optical axis by a predetermined angle α are measured. Furthermore, measuring the reference optical axis which coincides with the horizontal optical axis L _1, the angle between the optical axis L ₃ of the reflected light traveling in a direction away from the reference optical axis as an inclined angle.

As described above, according to the present embodiment, as the relative reflected light intensity distribution data, the intensity of the specular reflected light traveling along the reference optical axis, the optical axis of the reflected light traveling in a direction other than the regular reflected light, and the reference light It is possible to measure the inclination angle α (°) formed by the axis and the intensity of reflected light traveling in a direction different from that other than the specularly reflected light, particularly the relative reflected light intensity with respect to the intensity of the specularly reflected light.

The value of the tilt angle, which is the angle between the reference optical axis of the regular reflected light and the optical axis of the reflected light having a relative reflected light intensity of 50% of the intensity of the regular reflected light, is 18 ° or more. preferable. More preferably, the value of the inclination angle thus determined is 20 ° or more, and further preferably, the value of the inclination angle thus determined is 24 ° or more, and particularly preferably, the value of the inclination angle is 28 °. More than °.
Note that the value of the inclination angle between the reference optical axis of the regular reflected light and the optical axis of the reflected light having a relative reflected light intensity of 50% of the intensity of the regular reflected light is, for example, 70 ° or less.

Further, the value of the inclination angle of the optical axis of the reflected light having the relative reflected light intensity of 10% of the intensity of the regular reflected light with respect to the reference optical axis is preferably 70 ° or more. More preferably, the value of the inclination angle thus determined is 72 ° or more, and further preferably, the value of the inclination angle thus determined is 74 ° or more, and particularly preferably, the value of the inclination angle is 76 °. More than °.
As described above, the inclination angle of the optical axis of the reflected light having a relative reflected light intensity of 50% of the intensity of the regular reflected light or the reflected light having a relative reflected light intensity of 10% of the intensity of the regular reflected light. When a light diffusion molded product that satisfies the requirements for the tilt angle of the optical axis is used for a transparent screen, it is possible to widen the viewing angle, especially the viewing angle of reflected light when light for displaying an image is incident. It is.

As described above, when incident light is not incident perpendicularly to the light receiving surface of the flat sample but incident from a direction inclined with respect to the normal to the light receiving surface, the optical axis of the incident light and the reflected light are reflected. The reflected light plane including the observation point is tilted. For this reason, the intensity of the reflected light can be suppressed to a certain level, and the relative intensity value and intensity ratio of the reflected light can be easily measured. That is, the relative intensity of the reflected light can be accurately measured by inclining the optical axis of the incident light by about 5 ° with respect to the perpendicular perpendicular to the plane sample.
In addition, as illustrated in FIG. 1, it is also recognized that the space in which the light receiving device is arranged can be easily secured by sufficiently increasing the distance between the optical axis of the incident light and the optical axis of the reflected light.

The intensity of the incident light, the thickness of the planar sample, and the distance from the intersection to the observation point do not change each value of the relative intensity of the reflected light, and can be set as appropriate. it can.

When the incident light is incident at an angle of 45 ° with respect to the normal of the flat sample in a state where the flat sample of the light diffusion molded body is arranged at a predetermined reference position, the optical axis of the incident light is separated from the normal. The spectral spectrum of diffusely reflected light that diffuses while reflecting in the opposite direction is measured. That is, as illustrated in FIG. 4, incident light La from the light source 10 installed above the planar sample 20 is incident at an angle of 45 ° with respect to the normal of the planar sample 20, and diffused reflected light generated at this time The intensity of Lb is measured while rotating the light receiving unit 30 every 1 ° around the incident point on the flat sample 20.
As a result of this measurement, the values of a * and b * of the light diffusion molded body expressed in the CIE 1976 color space calculated by a method in accordance with JIS-Z-8781-4 are as follows: And (ii) are preferably satisfied. That is,
(I) The value of a * is −5 or more and 5 or less,
(Ii) The value of b * is preferably −10 or more and 10 or less.
The value of a * is more preferably -3 or more and 3 or less, and further preferably -1 or more and 1 or less.
Further, the value of b * is more preferably −7 or more and 7 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. That is, if the diffusibility of reflected light is improved, the color reproducibility may decrease, but the conditions (i) and
It can be said that the light diffusion molded body satisfying (ii) has both the b * value and the a * value close to 0, and the color balance in the reflected light is good.

Further, in the light diffusion molded article, the saturation C * expressed in the CIE 1976 color space calculated by the method based on JIS-Z-8781-4 from the spectral spectrum of the diffuse reflected light measured under the above conditions. It is preferable that the value further satisfies the following condition (iii). That is,
(Iii) C * is more preferably −10 or more and 10 or less.
The value of C * is more preferably from −7 to 7 and even more preferably from −5 to 5.
Further, in the light diffusion molded article, the value of the hue h * expressed in the CIE 1976 color space calculated by a method based on JIS-Z-8781-4 from the spectrum of diffusely reflected light measured under the above conditions. However, it is preferably 200 or more and 350 or less, more preferably 250 or more and 300 or less, and further preferably 260 or more and 275 or less.

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, and a hot bending method, a curved surface processing method, a free processing method, and the like. 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. However, the transparent screen film of the present invention has particularly good viewing angle characteristics of reflected light. Particularly suitable for reflective screen applications.

[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)
(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 (MT3300EXII manufactured by Microtrac Bell Co., Ltd.) using a laser diffraction scattering method to obtain a volume converted average particle diameter D50. As a result, D50 of B1 particles before processing was 0.94 μm, and B2 particles after processing was 0.27 μm.
(B3) Particle processing of bismuth metal oxide (bismuth oxide containing neodymium oxide, 42-920A manufactured by Toago Material Technology Co., Ltd.) by plasma processing is performed by nanoparticle processing manufactured by Nisshin Engineering Co., Ltd. The system was used to evaporate the particles with a thermal plasma generated in a high-frequency magnetic field and agglomerate again to obtain nanoparticles. The specific surface area of the obtained particles was measured using a specific surface area measurement apparatus (Macsorb HM model-1208 manufactured by Mountec Co., Ltd.) using the BET method. The BET specific surface area of the B1 particles before processing was 1. The B3 particle after processing was 15.5 m2 / 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) Zirconia particles (zirconium oxide, zirconia methanol dispersion SZR-M particle concentration 30.5 wt%, manufactured by Sakai Chemical Industry Co., Ltd.)
(B9) Zirconia particles (zirconium oxide, UEP manufactured by Daiichi Rare Element Chemical Industries, Ltd.)
(B10) Zirconia particles (zirconium oxide, SPZ manufactured by Daiichi Rare Element Chemical Industries, Ltd.)
(B11) Titania particles (titanium oxide, TITANIX JR-405 manufactured by Teika Co., Ltd.)
(B12) 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 were melted and extruded with a vented twin-screw film extruder (TEX-30α manufactured by Nippon Steel Co., Ltd.) with a T-die lip having a screw diameter of 30 mm to produce a film-like molded product. .

[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 pressure-sensitive adhesive was applied to the release-treated surface of a 25 μm-thick release PET film using a gravure roll or bar coater, and then heated and dried in an oven to a thickness of 17 μm. A 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 size 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 was IM-4000 manufactured by Hitachi High-Technologies, and the apparatus used for cross-sectional observation by FE-SEM was 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. 5, 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 reflected 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.

Using the mountain-shaped distribution curve data of the relative reflected light intensity distribution, the peak intensity of the peak, that is, the emission angle corresponding to half the intensity of the regular reflected light (half half width at half maximum), and the peak The emission angle (1/10 value half width) corresponding to the intensity of 1/10 of the peak intensity was calculated.
・ Measurement conditions: reflection ・ High Volt Adj: −900
Sensitivity Adj: 700
・ Flux diaphragm: 3.0
・ Light-receiving aperture: 4.0
-Incident angle: 0 °
・ Sample tilt angle: 5 °
・ Reception start angle: -45 °
・ Reception angle: 90 °
・ Measurement pitch: 0.1 ° interval

[Color of diffused light]
<Measuring method of a * value and b * value>
Normal direction with respect to the molded body under the following measurement conditions using the variable angle spectrocolorimetry system GCMS-4B (measuring machine model: GSP-2) using a halogen lamp manufactured by Murakami Color Research Co., Ltd. The spectral distribution of the reflected light was measured at each light receiving angle measured when the light was irradiated at a vertical angle of 45 °. Before the measurement, the sensitivity of the light source was adjusted under the condition that light was irradiated at 45 ° perpendicular to the normal white plate with respect to the standard white plate and the reflected light was received at 0 °. When expressed in the CIE 1976 color space by a method according to JIS-Z-8781-4 from the spectral distribution data of the reflected light rays diffusing in a direction that forms an angle of 0 ° with respect to the horizontal direction from the normal direction of the molded body. The values of a *, b *, saturation C *, and hue h * when expressed in the CIE 1976 color space were calculated from the spectral distribution data at the time of the calculation according to JIS-Z-8781-4.
・ Measurement conditions: Reflection ・ Light source: Standard Illuminant D65
-Field of view: 2 ° field of view-Incident angle: 45 °
・ Sample tilt angle: 0 °
・ Reception start angle: 0 °
・ Reception end angle: 80 °
Measurement pitch: 5 ° interval Next, the transparency of the molded product 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 a transparent screen, the films produced in the above-mentioned examples and comparative examples were placed at a position 12 cm away from the image projection lens of an ultrashort 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 rear, the image visibility when observed from 1 m behind 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 same surface of the projector, that is, screen reflected light. The evaluation results are shown in Table 1 and Table 2 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.
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,
When the incident light is irradiated toward the intersection of the perpendicular and the planar sample along an incident axis inclined by 5 ° with respect to a perpendicular perpendicular to the planar sample arranged at the reference position, the perpendicular is A plane that is perpendicular to the plane sample and that is also perpendicular to the plane that includes the normal and the incident axis, and is inclined by 5 ° to the opposite side of the incident axis. In the relative reflected light intensity distribution of the reflected light reflected along a certain reflected light plane,
Reference light of specularly reflected light, which is reflected light that is reflected along the intersection of the plane that includes the normal and the incident axis, and the reflected light plane is reflected by the incident light that is incident along the incident axis. A light diffusion molded article, wherein a value of an inclination angle that is an angle between an axis and an optical axis of reflected light having a relative reflected light intensity of 50% of the intensity of the regular reflected light is 18 ° or more.
When incident light is incident on the planar sample arranged at the reference position at an angle of 45 ° with respect to the normal, it is reflected in a direction opposite to the optical axis of the incident light across the normal. However, the values of a * and b * expressed in the CIE 1976 color space calculated by a method based on JIS-Z-8781-4 from the spectrum of diffusely reflected diffused light are as follows: And the light-diffusion molded object of Claim 1 which satisfy | fills (ii).
(I) The value of a * is −5 or more and 5 or less.
(Ii) The value of b * is −10 or more and 10 or less.
The value of saturation C * expressed in the CIE 1976 color space calculated from the spectrum of the diffusely reflected light by a method according to JIS-Z-8781-4 further satisfies the following condition (iii): 2. A light diffusion molded article according to 2.
(Iii) C * is −10 or more and 10 or less.
The value of the inclination angle of the optical axis of the reflected light having a relative reflected light intensity of 10% of the intensity of the regular reflected light with respect to the reference optical axis is 70 ° or more. The light-diffusion molded object of description.
The value of the inclination angle of the optical axis of the reflected light having a relative reflected light intensity of 50% of the intensity of the regular reflected light with respect to the reference optical axis is 18 ° or more and 70 ° or less. A light diffusion molded article according to claim 1.
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 5, comprising any one or more of any mixture.
The light diffusion molded article according to claim 6, wherein the light diffusion particles include at least a Bi oxide, a composite oxide, and a mixture of at least one of the oxide and the composite oxide.
The light diffusion molded article according to any one of claims 1 to 7, wherein the Z average particle diameter of the light diffusion particles is 100 to 3000 nm.
The light diffusion molded article according to any one of claims 1 to 8, wherein the number average particle diameter value of the light diffusion particles contained in the light diffusion molded article is 100 to 2000 nm.
10. 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 a 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 10, 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 11, 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 12, wherein the transparent resin binder contains a thermoplastic resin.
The light diffusion molded article according to claim 13, wherein the thermoplastic resin includes a polycarbonate resin.
A transparent screen film comprising the light diffusion molded product according to any one of claims 1 to 14.