JPWO2019208769A1 - Evaluation method for light diffusion molded body, transparent screen film, and light diffusion molded body - Google Patents

Abstract

Provided are a light diffusion molded body having particularly excellent viewing angle characteristics and color reproducibility, a film for a transparent screen, and the like. The above-mentioned problem is a light diffusion molded body containing a transparent resin binder and light diffusing particles, in which a flat sample of the light diffusing molded body is placed at a reference position and is perpendicular to the flat sample placed at the reference position. From the value of the relative transmitted light intensity of the transmitted light transmitted through the flat sample, which is measured when the incident light is irradiated toward the intersection of the vertical line and the flat sample along the incident axis inclined by 10 ° with respect to the vertical line. The solution was solved by a light diffusion molded body in which the value of the degree of diffusion D defined by the following formula (1) is 20 or more. [Equation 1] (However, in the above formula (1), D, I5, I20, and I70 represent values as defined in the specification).

Description

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

Conventionally, a transparent screen for displaying an image for advertising a product or the like has been known (for example, Patent Documents 1 and 2). As such a transparent screen, a thin resin layer to which fine particles are added is adopted, and an image projected from a projector is displayed on the transparent screen.

Japanese Patent No. 5725834 WO2016 / 093181

In a light diffusion molded product including a conventional transparent screen or the like, it is required that the performance such as transparency reaches a practical level.

However, many of the conventional light diffusion molded products do not have sufficient performance. For example, when a light diffusion molded body is used as a transparent screen for projecting a moving image or a still image, the visibility of the projected image may not always be good.

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

Further, in an image projected on a transparent screen based on a specific image data, a specific color, for example, blue is emphasized as compared with an image displayed on another display device based on the same image data. Was sometimes reduced. 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. It is considered that this is because the particle size of the light diffusing particles is small, so that the dimming efficiency of short wavelength light, that is, blue light is high, and the light is more diffused.

As a result of diligent studies to solve the above-mentioned problems, the present inventors have obtained a light diffusion molded body which is particularly good in viewing angle characteristics and color reproducibility and is particularly suitable for use in transparent screens. Further, they have found that a film for a transparent screen or the like can be realized, and have completed the present invention.
That is, a light diffusion molded product capable of achieving the above-mentioned excellent characteristics and a film for a transparent screen have been realized.
The present invention relates to a light diffusion molded product shown below, a film for a transparent screen, and the like.

（ただし、上記式（１）において、
Ｄは拡散度であり、
Ｉ_５，Ｉ_２０，及び、Ｉ_７０は、一定強度の前記入射光を前記交点に入射させたときに、前記垂線を含むとともに前記基準位置にある前記平面試料に対して垂直な平面であって、前記垂線と前記入射軸とを含む平面に対しても垂直な仮想の垂直平面上にあって、前記垂線に対する角度θがそれぞれ、５°，２０°，及び、７０°であるとともに前記交点からの距離が互いに等しい観測点における前記透過光の相対透過光強度の値を示す。）
（２）前記基準位置に配置した前記平面試料に対して、前記垂線に沿って入射光を照射したときに、前記平面試料に対して角度４５°をなす方向へ拡散する透過光の分光スペクトルから、ＪＩＳ−Ｚ−８７８１−４に準拠した方法で算出されるＣＩＥ１９７６色空間で表したａ＊、及び、ｂ＊の値が、下記の条件（ｉ）及び、（ｉｉ）を満たす、上記（１）に記載の光拡散成形体。
（ｉ）ａ＊の値が、−５以上５以下である。
（ｉｉ）ｂ＊の値が、−１５以上１５以下である。
（３）前記透過光の分光スペクトルから、ＪＩＳ−Ｚ−８７８１−４に準拠した方法で算出されるＣＩＥ１９７６色空間で表した彩度Ｃ＊の値が、下記の条件（ｉｉｉ）をさらに満たす、上記（２）に記載の光拡散成形体。
（ｉｉｉ）Ｃ＊が、−１０以上１０以下である。
（４）前記交点に対して、前記入射光を前記入射軸に沿って照射したときに、前記基準位置に配置した前記平面試料を透過して前記垂線に沿って進む基準透過光の透過光強度に対して１／２の相対透過光強度を有する透過光が観測される前記垂直平面上の観測点と、前記交点とを通る線の前記垂線に対する角度θ_１が１０．８°以上である、上記（１）〜（３）のいずれか一項に記載の光拡散成形体。
（５）前記交点に対して、前記入射光を前記入射軸に沿って照射したときに、前記基準位置に配置した前記平面試料を透過して前記垂線に沿って進む基準透過光の透過光強度に対して１／１０の相対透過光強度を有する透過光が観測される前記垂直平面上の観測点と、前記交点とを通る線の前記垂線に対する角度θ_２が３０°以上である、上記（１）〜（３）のいずれか一項に記載の光拡散成形体。
（６）前記拡散度Ｄの値が８０以下である、上記（１）〜（５）のいずれか一項に記載の光拡散成形体。
（７）前記光拡散粒子が、Ｂｉ、Ｎｄ、Ｓｉ、Ａｌ、Ｚｒ、及び、Ｔｉからなる群から選ばれる少なくとも１種の元素の酸化物、複合酸化物、及び、該酸化物及び該複合酸化物の少なくともいずれかの混合物のうちいずれか一種以上を含む、上記（１）〜（６）のいずれか一項に記載の光拡散成形体。
（８）前記光拡散粒子が、少なくともＢｉの酸化物、複合酸化物、及び、該酸化物及び該複合酸化物の少なくともいずれかの混合物のうち、いずれか一種以上を含む、上記（７）に記載の光拡散成形体。
（９）前記光拡散粒子のＺ平均粒子径が１５０〜３５００ｎｍである、上記（１）〜（８）のいずれか一項に記載の光拡散成形体。
（１０）前記光拡散成形体に含まれる前記光拡散粒子の個数平均粒子径の値が１００〜２３００ｎｍである、上記（１）〜（９）のいずれか一項に記載の光拡散成形体。
（１１）前記光拡散成形体に含まれる前記光拡散粒子の個数を基準として１５％以上の前記光拡散粒子の粒子径が、３００〜２０００ｎｍの範囲内にある、上記（１）〜（１０）のいずれか一項に記載の光拡散成形体。
（１２）前記透明樹脂バインダ１００質量部に対し、前記光拡散粒子を０．００１〜３質量部含有する、上記（１）〜（１１）のいずれか一項に記載の光拡散成形体。
（１３）前記光拡散粒子の多分散指数が０．８以下である、上記（１）〜（１２）のいずれか一項に記載の光拡散成形体。
（１４）前記透明樹脂バインダが熱可塑性樹脂を含む、上記（１）〜（１３）のいずれか一項に記載の光拡散成形体。
（１５）前記熱可塑性樹脂がポリカーボネート樹脂を含む、上記（１４）に記載の光拡散成形体。
（１６）上記（１）〜（１５）のいずれか一項に記載の光拡散成形体を含む、透明スクリーン用フィルム。(1) A light diffusion molded product containing a transparent resin binder and light diffusion particles.
A flat sample of the light diffusion molded product is placed at a reference position, and the light diffusion molded product is placed at a reference position.
It is measured when incident light is irradiated toward the intersection of the vertical line and the flat surface sample along an incident axis inclined by 10 ° with respect to a vertical line perpendicular to the flat surface sample arranged at the reference position. A light diffusion molded body 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 flat sample.

(However, in the above formula (1),
D is the degree of diffusion,
I ₅ , I ₂₀ , and I ₇₀ are planes that include the perpendicular and are perpendicular to the plane sample at the reference position when the incident light of constant intensity is incident on the intersection. , On a virtual vertical plane perpendicular to the plane including the perpendicular and the incident axis, the angles θ with respect to the perpendicular are 5 °, 20 °, and 70 °, respectively, and from the intersection. The value of the relative transmitted light intensity of the transmitted light at the observation points where the distances are equal to each other is shown. )
(2) From the spectral spectrum of transmitted light diffused in a direction forming an angle of 45 ° with respect to the plane sample when the plane sample placed at the reference position is irradiated with incident light along the perpendicular line. , The values of a * and b * expressed in the CIE1976 color space calculated by the method conforming to JIS-Z-8781-4 satisfy the following conditions (i) and (ii), as described in (1) above. ). The light diffusion molded body.
(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 CIE1976 color space calculated from the spectral spectrum of the transmitted light by a method based on JIS-Z-8781-4 further satisfies the following condition (iii). The light diffusion molded body according to (2) above.
(Iii) C * is -10 or more and 10 or less.
(4) When the incident light is irradiated to the intersection along the incident axis, the transmitted light intensity of the reference transmitted light that passes through the plane sample arranged at the reference position and travels along the perpendicular line. _{The angle θ 1 of the} line passing through the intersection and the observation point on the vertical plane where the transmitted light having a relative transmitted light intensity of 1/2 is 10.8 ° or more. The light diffusion molded body according to any one of (1) to (3) above.
(5) When the incident light is irradiated to the intersection along the incident axis, the transmitted light intensity of the reference transmitted light that passes through the plane sample arranged at the reference position and travels along the perpendicular line. _{The angle θ 2 of the} line passing through the observation point on the vertical plane where the transmitted light having a relative transmitted light intensity of 1/10 of the relative transmitted light is observed and the intersection is 30 ° or more. The light diffusion molded body according to any one of 1) to (3).
(6) The light diffusion molded product according to any one of (1) to (5) above, wherein the value of the degree of diffusion D is 80 or less.
(7) An oxide, a composite oxide, and an oxide and the composite oxidation of at least one element selected from the group consisting of Bi, Nd, Si, Al, Zr, and Ti in which the light diffusing particles are formed. The light diffusion molded product according to any one of (1) to (6) above, which comprises at least one of at least one mixture of the same.
(8) In the above (7), the light diffusing particles contain at least one or more of an oxide of Bi, a composite oxide, and at least one mixture of the oxide and the composite oxide. The light diffusion molded body according to the above.
(9) The light diffusion molded product according to any one of (1) to (8) above, wherein the Z average particle diameter of the light diffusion particles is 150 to 3500 nm.
(10) The light diffusion molded body according to any one of (1) to (9) above, wherein the value of the number average particle diameter of the light diffusing particles contained in the light diffusion molded body is 100 to 2300 nm.
(11) The above (1) to (10), wherein 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 body according to any one of the above items.
(12) The light diffusion molded product according to any one of (1) to (11) above, which contains 0.001 to 3 parts by mass of the light diffusing particles with respect to 100 parts by mass of the transparent resin binder.
(13) The light diffusion molded product according to any one of (1) to (12) above, wherein the polydisperse index of the light diffusion particles is 0.8 or less.
(14) The light diffusion molded product according to any one of (1) to (13) above, wherein the transparent resin binder contains a thermoplastic resin.
(15) The light diffusion molded product according to (14) above, wherein the thermoplastic resin contains a polycarbonate resin.
(16) A film for a transparent screen containing the light diffusion molded product according to any one of (1) to (15) above.

In the transparent resin binder, the light diffusing molded body of the present invention containing the light diffusing particles, and the transparent screen film, the transmitted light traveling in the direction away from the incident direction of the incident light also has a certain intensity or more. Have. Therefore, it can be said that the light diffusion molded product and the transparent screen film of the present invention are particularly excellent in viewing angle characteristics, and also have 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 body. It is a top view which shows an example of the measuring apparatus for measuring the transmitted light distribution of a light diffusion molded body. It is a figure which shows typically the method of measuring the particle diameter based on the cross-section observation of a resin film. It is a figure which shows typically the method of measuring the spectral spectrum of the light ray which transmitted through a light diffusion molded body. It is a graph which shows the spectral spectrum (relative transmitted light intensity) of the light ray which transmitted through the light diffusion molded body of an Example and a comparative example.

Hereinafter, the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be arbitrarily modified and implemented as long as the invention has an effect.

[Light diffusion molded body]
The light diffusing molded article of the present invention contains a transparent resin binder and light diffusing particles. The light diffusion molded body can diffuse the incident light over a wide range and has a high viewing angle characteristic, so that it is particularly suitable for use as a film for a transparent screen. The transmitted light traveling in the direction away from the incident direction also has a certain intensity or more. Therefore, it can be said that the light diffusing molded product and the transparent screen film of the present invention are particularly excellent in light diffusing property and have high color reproducibility.

In the light diffusion molded body, 0.001 to 3 parts by mass (about 0.001 to about 3.0% by mass) of light diffusing particles are contained in 100 parts by mass of the transparent resin binder. Is preferable. The light diffusion molded body more preferably contains 0.01 to 1 part by mass of light diffusion particles with respect to 100 parts by mass of the transparent resin binder, and more preferably the light diffusion particles with respect to 100 parts by mass of the transparent resin binder. Is contained in an amount of 0.03 to 0.5 parts by mass, and particularly preferably, the light diffusing particles are contained in an amount of 0.1 to 0.3 parts by mass 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 can be ensured, a sufficient scattering effect of the projected light can be obtained, and the visibility of the image such as color reproducibility can be obtained. Will also be good.

<Transparent resin binder>
A transparent resin binder is used as a main constituent material of the light diffusion molded product. In order to improve the strength and durability of the transparent screen film, the transparent resin binder preferably contains a hard thermoplastic resin. Further, in order to improve the transparency of the transparent screen film, it is preferable to contain 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 of these.
In particular, the transparent resin binder preferably contains at least one selected from the polycarbonate resin and the polyester resin among the above-mentioned thermoplastic resin options.

For example, the above-mentioned polycarbonate resin contains a carbonate ester bond in the molecular main chain- [OR-OCO] -unit (R is an aliphatic group, an aromatic group, or both an aliphatic group and an aromatic group. It is not particularly limited as long as it contains (the one having a linear structure or a branched structure). However, aromatic polycarbonate is more preferable because of its impact resistance and heat resistance, its stability as an aromatic dihydroxy compound, and the fact that it is easy to obtain a compound containing a small amount of impurities. Be 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, and examples thereof include a polycarbonate polymer obtained by reacting a dihydroxy compound with 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. Alternatively, a method of reacting carbon dioxide with cyclic ether using carbon dioxide as a carbonate precursor may also be used. Further, the polycarbonate polymer may be a copolymer composed of one type of repeating unit or a copolymer having two or more types of repeating units. At this time, as the copolymer, various copolymer forms such as a random copolymer and a block copolymer can be selected.

The method for producing the polycarbonate resin is not particularly limited, and any method can be adopted. Examples thereof 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.

また、上述のポリエステル樹脂としては、例えば、ＰＥＴＧ（シクロヘキサンジメタノールによりグリコール変性されたポリエチレンテレフタレート）等が使用される。The molecular weight of the polycarbonate resin is preferably 10,000 to 35,000, more preferably 10,500 or more, which is a viscosity average molecular weight converted from the solution viscosity measured at a temperature of 25 ° C. using methylene chloride as a solvent. , More preferably 11,000 or more, still more preferably 11,000 or more, and even more preferably 12,000 or more. The viscosity average molecular weight of the polycarbonate resin is preferably 32,000 or less, more preferably 29,000 or less. By setting the viscosity average molecular weight to the lower limit of the above range or more, the mechanical strength of the resin molded product of the present invention can be further improved, and by setting the viscosity average molecular weight to the upper limit of the above range or less, the resin It is possible to suppress and improve the decrease in fluidity, improve the molding processability, and facilitate the thin-wall molding process.
Two or more types of polycarbonate resins having different viscosity average molecular weights may be mixed and used. In this case, a polycarbonate resin having a viscosity average molecular weight outside the above-mentioned suitable range may be mixed.
The viscosity average molecular weight [Mv] is defined by using methylene chloride as a solvent and determining the ultimate viscosity [η] (unit: dl / g) at a temperature of 25 ° C. using an Ubbelohde viscometer. , Η = 1.23 × 10 ^-4 Mv ^0.83 means a value calculated from. The ultimate viscosity [η] is a value calculated by the following formula by measuring _{the specific viscosity [η sp} ] at each solution concentration [C] (g / dl).

Further, as the polyester resin described above, for example, PETG (polyethylene terephthalate glycol-modified with 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 the thermoplastic resin, and more preferably 90% by mass or more of the thermoplastic resin.

The photocurable resin contained in the transparent resin binder may be either an ultraviolet curable resin or an electron beam curable resin, and is, for example, an acrylic resin, a silicone resin, an ester resin, or the like. Specific examples of the ultraviolet curable resin include ultraviolet curable resins having an acryloyl group in the molecule, for example, epoxy acrylate-based, urethane acrylate-based, polyester acrylate-based, polyol acrylate-based oligomers, polymers and monofunctional / bifunctional / Alternatively, polyfunctional polymerizable (meth) acrylic monomers such as tetrahydrofurfuryl acrylate, 2-hydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, trimethyl propantriacrylate, Mixtures of monomers such as pentaerythritol triacrylate, pentaerythritol tetraacrylate, oligomers, polymers and the like are used. The photocurable resin may contain a photopolymerization initiator or the like which is usually blended.
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 type epoxy resin, phenol novolac type epoxy resin, biphenyl type epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, heterocycle Various novolak type epoxy resins, bisphenol A type epoxy resins, brominated bisphenol A type epoxy resins, etc. synthesized from a formula epoxy resin, a halogenated epoxy resin, a spirocyclic epoxy resin, bisphenol A, resorcin and the like are used.

<Light diffusion particles>
The light diffusing molded product contains atomized light diffusing particles. As the light diffusing particles, for example, those containing a metal oxide are used. More specifically, the light diffusing particles are oxides, composite oxides, and oxides of at least one element selected from the group consisting of, for example, Bi, Nd, Si, Al, Zr, and Ti. And, it is preferable to contain any one or more of the mixture of at least one of the composite oxides. The light diffusing particles more preferably contain at least one selected from bismuth oxide, zirconium oxide, silica, titania (titanium oxide), and alumina. As the light diffusing particles, those containing bismuth oxide, that is, those containing an oxide of bismuth, a composite oxide, and at least one mixture of the oxide and the composite oxide are particularly preferable. A screen film containing these light-diffusing particles, particularly the above-mentioned light-diffusing particles mentioned as a preferred option, can particularly improve the color reproducibility of an image when projected by a projector.

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

The light diffusing particles preferably have a Z average particle size of 150 nm to 3500 nm. The Z average particle size of the light diffusing particles is more preferably 180 nm to 3000 nm, still more preferably 200 nm to 2000 nm. As described above, the light diffusing molded body using the light diffusing particles used for the conventional transparent screen for projection, for example, the light diffusing particles having a diameter larger than that of the light diffusing particles having a particle diameter of about several tens of nm, is As will be described in detail later, it is possible to realize a transparent screen having excellent light transmittance, light diffusivity, and color reproducibility.
The Z average particle size 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 size and the polydisperse index (PDi) are obtained, and in the present invention, this average particle size is defined as the Z average particle size.
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 + ...
The constant b of is called a quadratic cumulant or Z average diffusion coefficient.
The Z average particle diameter is a value obtained by converting the value of this constant b into a particle size using the viscosity of the dispersion medium and some device constants. This Z average particle size value 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. For c, which is a coefficient of the square term, ^{the value of 2c / b 2} is called the polyvariance index (PDi).
Specifically, the Z average particle size, which is an index of dispersibility in the present invention, can be measured by 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. is used to prepare a solution after the light diffusing particles are put into pure water and the particles are dispersed by using ultrasonic waves. The value of the Z average particle size can be obtained by measuring with.

Further, the polydispersity index of the light diffusing particles is preferably 0.8 or less. Further, the polydispersity index of the light diffusing particles is more preferably 0.7 or less, and particularly preferably 0.5 or less. As described above, by using the light diffusing particles having a small polydisperse index value, it is possible to remove the light diffusing particles having an extremely large diameter or an extremely small diameter in the light diffusing molded body.

[Other components contained in the light diffusion molded product]
As a component other than the transparent resin binder and the light diffusing particles in the light diffusing molded product, for example, the following additives may be contained. For example, in a light diffusion molded body used as a film for a transparent screen, it was selected from the group consisting of a heat stabilizer, an antioxidant, a flame retardant, a flame retardant, an ultraviolet absorber, a mold release agent, and a colorant. At least one kind of additive and the like. Antistatic agents, fluorescent whitening agents, antifogging agents, fluidity improvers, plasticizers, dispersants, antibacterial agents and the like may be added as long as the desired physical properties are not significantly impaired.

（式（１）中、Ｒ^１およびＲ^２はそれぞれ独立に、炭素原子数１〜３０のアルキル基または炭素原子数６〜３０のアリール基を表す。）

（式（２）中、Ｒ^３〜Ｒ^７は、それぞれ独立に、水素原子、炭素原子数６〜２０のアリール基または炭素原子数１〜２０のアルキル基を表す。）
The light diffusion molded article of the present invention preferably contains an antioxidant.
Examples of the antioxidant include phenol-based antioxidants, amine-based antioxidants, phosphorus-based antioxidants, thioether-based antioxidants, and the like, and phosphorus-based antioxidants and phenol-based antioxidants (more preferably hinder). Dophenol-based antioxidants) are preferred. Among them, a phosphorus-based antioxidant is particularly preferable because it can form a resin molded product having an excellent hue.
Among the phosphorus-based antioxidants, a phosphite-based stabilizer is preferable, and as the phosphite-based stabilizer, a phosphite compound represented by the following formula (1) or (2) is preferable.

(In the formula (1), R ¹ and R ² independently represent an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms.)

(In the formula (2), R ^{3 to} R ⁷ independently represent 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 linear or branched alkyl groups having 1 to 10 carbon atoms, respectively. When ^{at least one of R 1} and R ² is an aryl group, the aryl group represented by any of the following general formulas (1-a), (1-b), or (1-c) is preferable.

（式（１−ａ）中、Ｒ^Ａは、それぞれ独立に、炭素数１〜１０のアルキル基を表す。式（１−ｂ）中、Ｒ^Ｂは、それぞれ独立に、炭素数１〜１０のアルキル基を表す。）

(In the formula (1-a), ^{R A} is independently, in represents an alkyl group having 1 to 10 carbon atoms. Formula (1-b), ^{R B} are each independently, 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% by mass, more preferably 0.01 to 0.5% by mass, based on the total mass of the light diffusion molded body. It is more preferably 0.02 to 0.3% by mass.

In the light diffusion molded body, 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.

[Manufacturing of light diffusion molded article]
The light diffusion molded product is produced by blending a material substance such as the above-mentioned transparent resin binder and 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 pellets, and may be flakes, powders, bulks, or the like.
Further, by molding the resin composition into a predetermined shape, a light diffusion molded product can be obtained. For example, a light diffusion molded product as a film for a transparent screen can be produced by a step of processing the resin composition into a film or a sheet.

[Film for transparent screen]
The transparent screen film of the present invention includes the above-mentioned light diffusion molded product. More specifically, the transparent screen film of the present invention is formed mainly by a light diffusion molded body, preferably only by a light diffusion molded body.
As described above, for example, the thickness of the light diffusion molded product used as a film for a transparent screen 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 product, 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 size of 150 nm to 3500 nm, and the Z average particle size is more preferably 180 nm to 3000 nm, still more preferably 200 nm to 2000 nm. ..
As described above, the solvent for dissolving the transparent screen film in order 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. A solvent having a high solubility of the resin is preferable, and specific examples thereof include dichloromethane, toluene, xylene, tetrahydrofuran, 1,4-dioxane, dimethylformamide, N-methylpyrrolidone, ethyl acetate, cyclohexanone, acetone, methylethylketone, methanol, cyclohexane and the like. Of these, dichloromethane (CH ₂ Cl ₂ ) is preferable.

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

The average number of particle sizes of the light diffusing particles contained in the light diffusing molded product calculated in this way 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.
Regarding the particle size distribution of the light diffusing particles in the transparent screen film, the light diffusing particles having the number average particle size in the range of 300 to 2000 nm are 15% of the total number of the light diffusing particles. It is preferable to occupy the above, more preferably 20% or more, further preferably 40% or more, and particularly preferably 60% or more.

The components of the light diffusing particles in the transparent screen film are as described in the above <Light diffusing particles> column. For example, from the group consisting of Bi, Nd, Si, Al, Zr, and Ti. It is preferable to contain at least one of an oxide of at least one element selected, a composite oxide, and a mixture of at least one of the oxide and the composite oxide. 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 bismuth oxide and composite oxide. , And at least a mixture of the oxide and the composite oxide.

When the above-mentioned light diffusing 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 size of the light diffusing particles is reduced to improve the diffusivity and the viewing angle is widened. There was a problem of color reproducibility such as excess. On the other hand, when the above-mentioned type of light diffusing particles is used, it is possible to realize good color reproducibility while widening the viewing angle.
The components of the light diffusing particles in the transparent screen film can be confirmed by, for example, energy dispersive X-ray (EDX) analysis.

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 body. 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 mass of light diffusing particles with respect to 100 parts by mass of the transparent resin binder, and more preferably light diffusing with respect to 100 parts by mass of the transparent resin binder. The particles are contained in an amount of 0.03 to 0.5 parts by mass, and particularly preferably, the light diffusing particles are contained in an amount of 0.1 to 0.3 parts by mass with respect to 100 parts by mass of the transparent resin binder.

For example, in a light diffusion molded product which is a film for a transparent screen, the value of 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 therefore has excellent back visibility in a state where no image is projected from the projector. The value of the total light transmittance in the present specification is a value based on JIS-K-7361 and JIS-K-7136, which will be described later.

Further, for example, in a light diffusion molded product which is a film for a transparent screen, the haze value is preferably 80% or less, 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 project an image well. The haze value in the present specification is a value based on JIS-K-7361 and JIS-K-7136, which will be described later.

上記式（１）において、Ｄは拡散度であり、Ｉ_５，Ｉ_２０，及び、Ｉ_７０の各値は、以下のように測定される相対透過光強度の値である。For example, in a light diffusion molded product which is a film for a transparent screen, the value of the degree of diffusion D defined by the following formula (1) is 20 or more. As described above, in the transparent screen film formed of the light diffusing molded body having a large diffusivity D value, the effect of diffusing the transmitted light of the light incident (projected) on the surface of the film can be obtained, and the image can be obtained. Visibility is good.
The value of the degree of diffusion D is preferably 22 or more, more preferably 24 or more, and particularly preferably 30 or more. The value of the degree of diffusion D is preferably 80 or less, for example, 75 or less.

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

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

As described above, in order to calculate the degree of diffusion D, the plane sample is irradiated with incident light from a direction inclined by 10 ° with respect to the perpendicular line perpendicular to the plane 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 line perpendicular to the plane sample in this way is a diagram showing an example of a measuring device for measuring the transmitted light distribution of the light diffusion molded body. It is shown by 1.
In this way, if the incident light is not incident perpendicularly to the light receiving surface of the flat sample but is incident light from a direction inclined with respect to the perpendicular line of the light receiving surface, the optical axis of the incident light and a plurality of observation points Will be tilted with the virtual vertical plane containing. Therefore, the intensity of the transmitted light can be suppressed to a certain level, and the value of the relative transmitted light intensity of the transmitted light and the intensity ratio can be easily measured.
That is, by tilting the optical axis of the incident light by 10 ° with respect to the perpendicular line perpendicular to the flat sample, the relative intensity of the transmitted light can be accurately measured.

Further, by making the light receiving portion rotatable as shown in FIG. 2, as described above, the light receiving portion is on a virtual vertical plane perpendicular to the plane sample or the like, and the angle θ with respect to the perpendicular line can be set to various observation points. The light receiving part can be moved. For example, in the transmitted light distribution measuring device illustrated in FIG. 2, since the light receiving portion can rotate from + 90 ° to −90 °, the light receiving portion is set to 5 °, 20 ° with respect to the perpendicular line of the flat sample. And, it can be easily moved to the position of 70 °, so that _{each value of I 5} , I ₂₀ and I ₇₀ can be measured. The rotation positions of 5 °, 20 °, and 70 ° may be any of the + side and-side rotation positions illustrated in FIG.
The intensity of the incident light, the thickness of the flat sample, and the magnitude of the distance from the intersection to the observation point are the values of _{I 5} , I ₂₀ , and I _{70, which indicate the relative transmitted light intensity of the transmitted light.} Since it does not change, it can be set as appropriate.

As described above, when the incident light is applied to the intersection along the incident axis inclined by 10 ° with respect to the perpendicular line, the reference transmitted light transmitted through the plane sample at the reference position and travels along the perpendicular line. _{The angle θ 1} with respect to the perpendicular of the line passing through the intersection and the observation point on the vertical plane where the transmitted light having a relative transmitted light intensity of 1/2 of the light intensity is observed must be 10.8 ° or more. preferable.
Further, as described above, when the incident light is applied to the intersection along the incident axis inclined by 10 ° with respect to the perpendicular line, the reference transmission that passes through the flat sample arranged at the reference position and travels along the perpendicular line. _{The angle θ 2} with respect to the perpendicular of the line passing through the intersection and the observation point on the vertical plane where the transmitted light having a relative transmitted light intensity of 1/10 of the transmitted light intensity of the light is observed is 30 ° or more. Is preferable.
When a light diffusion molded product satisfying these requirements is used for the transparent screen, the viewing angle can be particularly widened.

In the light diffusion molded body, when the flat sample is placed at a predetermined reference position and the incident light is irradiated along the perpendicular line of the flat sample, the transmission diffuses in a direction forming an angle of 45 ° with respect to the flat sample. It is preferable that the values of a * and b * represented in the CIE1976 color space calculated by a method based on JIS-Z-8781-4 from the spectral spectrum of light satisfy the following conditions. That is,
(I) The value of a * is -5 or more and 5 or less, and further
(Ii) The value of b * is preferably -15 or more and 15 or less.
The value of a * is more preferably -4 or more and 4 or less, and further preferably -3 or more and 3 or less.
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 product satisfying the above-mentioned 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 spectral spectrum of transmitted light diffused in a direction forming an angle of 45 ° with respect to a flat sample, which is measured under the above conditions. It is preferable that the value of saturation C * expressed in the CIE1976 color space further satisfies the following condition (iii). That is,
(Iii) C * is preferably -10 or more and 10 or less, and more preferably -5 or more and 5 or less.

For example, in a light diffusion molded body which is a film for a transparent screen, the diffusivity when the wavelengths of the irradiation light to be irradiated are 400 nm, 500 nm, 600 nm, and 700 nm are B (400), B (500), and B (, respectively. When 600) and B (700) are used, the relative standard deviations of B (400), B (500), B (600), and B (700) (hereinafter, also simply referred to as relative standard deviations) are 0 to 20. It is preferably in the range of%. More preferably, the relative standard deviation values of B (400), B (500), B (600), and B (700) are 18% or less, and particularly preferably 15% or less.

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

Further, the YI value (ΔYI value according to JIS Z8722) of the transparent screen film is preferably 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, the transparent screen film having a small YI value (ΔYI value) suppresses a color change that may be caused by decomposition of the resin of the material, particularly a discoloration to yellow. Therefore, 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 producing a transparent screen. The term "transparent" described in the specification of the present application means that the image can be projected on the screen and has transparency that can realize a certain degree of transparent visibility. The transparent screen produced by the film for a transparent screen 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, an adhesive layer for adhering another layer to the transparent screen film, and the like 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 by using an adhesive composition. As the pressure-sensitive adhesive composition, for example, natural rubber-based, synthetic rubber-based, acrylic resin-based, polyvinyl ether resin-based, urethane resin-based, and silicone resin-based adhesive composition are used so as not to impair the optical characteristics and transmission visibility 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, isoprene-isoprene rubber, styrene-isoprene block copolymer, styrene-butadiene block copolymer, and styrene. -Antiethylene-butylene block copolymer can be mentioned. Specific examples of the silicone resin-based pressure-sensitive adhesive composition include dimethylpolysiloxane. These components may be used alone or in combination of two or more. Among these, it is preferable to form the pressure-sensitive adhesive layer by using a silicone-based pressure-sensitive adhesive, an acrylic-based pressure-sensitive 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.

The shape of the transparent screen film of the present invention may be either a flat surface or a curved surface, and may be two-dimensionally processed or three-dimensionally processed. The processing method is not particularly limited, but for example, a thermal processing method, a punching processing method, a cold bending processing method, a drawing processing method, and the like are preferably mentioned, and a thermal bending method, a curved surface processing method, and a free processing method are used. A blow molding method or the like is more preferable, and a press molding method, a vacuum forming method, a compressed air molding method, a natural leaving method, or the like is particularly preferable.

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

[Manufacturing method of transparent screen film]
As described above, the transparent screen film of the present invention is produced by using a light diffusion molded product. For example, a predetermined amount of light diffusing particles are added to the light diffusing molded product and melt-kneaded. Then, for example, pellets of a light diffusing molded product containing light diffusing particles are obtained by strand cutting. A film for a transparent screen can be produced by extruding the pellets of the light diffusion molded product thus obtained by, for example, a film extruder.

Further, the shape of the transparent screen film is adjusted by appropriately selecting and adopting the various processing methods described above. The transparent screen film whose shape is appropriately adjusted in this way is used in the production of the transparent screen. As a more specific manufacturing method, the methods of the following examples can be mentioned.

Hereinafter, the present invention will be described in more detail 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 manufactured by SK Chemicals, viscosity average molecular weight: 31,000)

・ Light diffusing particles (B) (inorganic particles)
(B1) Bismuth-based metal oxide (bismuth oxide containing neodymium oxide, 42-920A manufactured by Tokan Material Technology Co., Ltd.)
(B2) Particles obtained by crushing and classifying bismuth-based metal oxides (bismuth oxide containing neodymium oxide, 42-920A manufactured by Tokan Material Technology Co., Ltd.) are crushed and classified by an air class crusher manufactured by Nisshin Engineering Co., Ltd. Model: Super Jet Mill SJ-500) and an air classifier manufactured by Nisshin Engineering Co., Ltd. (Model: Aerofine Classia AC-20), and after crushing the particles with an airflow crusher, the air classifier Processed particles were obtained by removing the coarse particles in. The obtained particles were dispersed in pure water, and the particle size distribution was measured using a particle size distribution measuring device (MT3300EXII manufactured by Microtrac Bell Co., Ltd.) using a laser diffraction / scattering method to obtain a volume-equivalent average particle size D50. As a result, the D50 of the B1 particles before processing was 0.94 μm, and the B2 particles after processing were 0.27 μm.
(B3) Particles of bismuth-based metal oxides (bismuth oxide containing neodymium oxide, 42-920A manufactured by Tokan Material Technology Co., Ltd.) are made into nanoparticles by plasma processing. Nanoparticles were obtained by evaporating the particles with a thermal plasma generated in a high-frequency magnetic field and reaggregating them using a nanoparticle processing system. When the specific surface area of the obtained particles was measured using a specific surface area measuring device (Macsorb HM model-1208 manufactured by Mountech Co., Ltd.) using the BET method, the BET specific surface area of the B1 particles before processing was found. It was 1.8 m ² / g, and the processed B3 particles were 15.5 m ² / g.
(B4) Silica particles (silicon dioxide, Admanano YA050C-SP3 manufactured by Admatex Co., Ltd.)
(B5) Silica particles (silicon dioxide, Admafine SO-C1 manufactured by Admatex Co., Ltd.)
(B6) Silica particles (silicon dioxide, Admafine SC-2500SQ manufactured by Admatex Co., Ltd.)
(B7) Silica particles (silicon dioxide, Admafine SC-C6 manufactured by Admatex Co., Ltd.)
(B8) Alumina particles (aluminum oxide, Admafine AO-502 manufactured by Admatex Co., Ltd.)
(B9) Zirconia particles (zirconium oxide, zirconia methanol dispersion manufactured by Sakai Chemical Industry Co., Ltd. SZR-M particle concentration 30.5 wt%)
(B10) Zirconia particles (Zirconium oxide, UEP manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.)
(B11) Zirconia particles (zirconium oxide, SPZ manufactured by Daiichi Rare Element Chemical Industry Co., Ltd.)
(B12) Titania particles (titanium oxide, TITANIX JR-405 manufactured by TAYCA CORPORATION)
(B13) Titania particles (titanium oxide, TITANIX JR-301 manufactured by TAYCA CORPORATION)

・ Antioxidant (C)
Bis (2,6-di-tert-butyl-4-methylphenyl) Pentaerythritol diphosphite (phosphorus-based antioxidant, inhibitor ADEKA Corporation ADEKA STAB PEP-36)
-Release agent (D) Glycerin monostearate (Rikemar S-100A manufactured by RIKEN Vitamin Co., Ltd.)

[Measurement of Z average particle size and polydisperse index (Pdi) of light diffusing particles contained in the resin composition]
The Z average particle size and polydisperse index (Pdi) of the light diffusing particles (B) are obtained by cumulant analysis from the measurement results using a Zetasizer Nano ZS measuring device manufactured by Malvern Co., Ltd. using a dynamic light scattering method. It was. The measurement was carried out 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. Ultrasonic waves were used to disperse 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, the closer the PDi approaches to zero, and conversely, the wider the particle size distribution, that is, the greater the polydispersity. The larger the PDi, the larger.

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

[Manufacturing of thermoplastic resin film to which light diffusing particles are added]
The obtained pellets are melted and extruded with a vented twin-screw film extruder (TEX-30α manufactured by Japan Steel Works, Ltd.) with a T-die lip with a screw diameter of 30 mm to produce a sheet and film-shaped molded product. Made.

[Manufacturing Example 1 of Adhesive Layer]
A thermosetting paint was applied to the resin film of Example 4 thus formed using a metal bar coater, and then heated and dried in an oven to form a primer layer having a thickness of 1 μm. Then, using a reverse gravure roll, a silicone-based adhesive paint was applied, and then heated and dried in an oven to form an adhesive layer having a thickness of 50 μm.

[Manufacturing Example 2 of Adhesive Layer]
Further, an acrylic adhesive is applied to the release-treated surface of the PET film that has been subjected to the release treatment to a thickness of 25 μm using a gravure roll or a bar coater, and then heated and dried in an oven to a thickness of 17 μm. An adhesive film was formed. The pressure-sensitive adhesive layer surface of the pressure-sensitive adhesive film was attached to the resin film of Example 4 and pressed to transfer the pressure-sensitive adhesive layer to the resin film of Example 4. When the resin films with adhesive layers of Production Examples 1 and 2 in which the adhesive layer was formed in this way were attached to a glass plate having a thickness of 5 mm and visually observed, the film was very transparent. Further, when an image was projected on these resin films with an adhesive layer using an ultra-short throw projector (manufactured by Ricoh Co., Ltd., product name: PJ WX4152), 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 diffusing particles in resin film by cross-section observation (cross-section observation method)]
The resin film formed by the above method was cross-sectioned by ion milling for about 3 hours, and the obtained cross section was observed with a field emission scanning electron microscope (FE-SEM). The device used for this ion milling cross-section processing is IM-4000 manufactured by Hitachi High-Technologies Corporation, and the device used for cross-section observation by FE-SEM is SU-8220 manufactured by Hitachi High-Technologies Corporation. In the image observation mode for cross-sectional observation, an LA-BSE image was used, and the particle size of the particles that could be observed was measured when the magnification was 2000 times. At least 10 or more particles were observed for each film.

Based on the above observation data, the particle size d of each particle is determined.
It was calculated based on the formula (particle size (a) in the long side direction + particle size (b) in the short side direction) / 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 diameter passing through the center point of the cross section of the particle. It has a long particle diameter, and the particle diameter (b) is the shortest particle diameter that passes through the center point of the cross section of the particle.
Further, the value of the average particle size of a large number of particles was taken as the number average particle size Dav, and the calculation was performed by the following formula Σ (nd) / Σ (n) = Dav. In this equation, d represents the particle size of each particle, that is, each particle size, and n represents a percentage based on the number. Further, the ratio of the number of particles whose particle diameter d is in the range of 300 to 2000 nm to the total number of the above-mentioned observable particles was determined.
Furthermore, by energy dispersive X-ray (EDX) analysis, it was confirmed that the observed particles were light diffusing particles for which the particle size was calculated. The device used for EDX is X-Max ^{N component manufactured by HORIBA, Ltd.}

[Evaluation of optical characteristics of film]
The optical characteristics of the molded products 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 (manufactured by Murakami Color Technology Laboratory Co., Ltd., trade name: HM-150 type) with JIS-K-7361 and Measured according to JIS-K-7136.
Next, the mapping property of the molded product was measured by using a mapping property measuring machine (Suga Test Instruments Co., Ltd. model: ICM-1T) in accordance with JIS K7374, and the mapping property of the transmitted light of the molded product was measured. The value of image sharpness (%) when measured with an optical comb width of 0.125 mm was defined as mapability.

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

（上記式（１）において、Ｉθ（Ｉ_５，Ｉ_２０，及びＩ_７０）は、一定強度の入射光を、入射光の光軸と成形体の平面試料との交点に入射させたときに、垂線を含むとともにその平面試料に対して垂直な仮想の垂直平面上にあって、垂線に対する角度θがそれぞれ、５°，２０°，及び、７０°であるとともに交点からの距離が互いに等しい観測点における透過光の相対透過光強度の値を示す。）
・測定条件：透過
・Ｈｉｇｈ Ｖｏｌｔ Ａｄｊ：−９００
・Ｓｅｎｓｉｖｉｔｙ Ａｄｊ：５００
・光束絞り ：３．０
・受光絞り ：４．０
・入射角度 ：０°
・試料あおり角度：０°
・受光開始角度：−９０°
・受光終了角度：９０°
・測定ピッチ：０．１°間隔Using the obtained data of the relative transmitted light intensity distribution, the diffusivity D was calculated by the following formula (1). In addition, using the mountain-shaped distribution curve data of the relative transmitted light intensity distribution, the emission angle (1/2 value half width) corresponding to the intensity of 1/2 of the peak intensity of the mountain and the intensity of 1/10 of the peak intensity of the mountain are used. The emission angle (1/10 value half width) corresponding to was calculated.

(In the above formula (1), Iθ (I ₅ , I ₂₀ , and I ₇₀ ) is obtained when incident light of 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 perpendicular to the plane sample, and the angles θ with respect to the perpendicular line are 5 °, 20 °, and 70 °, respectively, and the distances from the intersections are equal to each other. Indicates the value of the relative transmitted light intensity of the transmitted light in.)
-Measurement conditions: Transmission-High Volt Adj: -900
-Sensivity Adj: 500
・ Luminous flux aperture: 3.0
・ Light receiving aperture: 4.0
・ Incident angle: 0 °
・ Sample tilt angle: 0 °
・ Light reception start angle: -90 °
・ Light reception end angle: 90 °
・ Measurement pitch: 0.1 ° interval

[Color of diffused light]
<Measurement method of a * value and b * value>
As outlined in FIG. 4, a variable-angle spectroscopic color measurement system GCMS-4B (measuring machine model: GSP-2) including a halogen lamp manufactured by Murakami Color Research Institute Co., Ltd. as a light source 10 and a variable-angle spectroscopic measuring instrument 30 The spectroscopy _{of the transmitted light L 2} at each light receiving angle measured when the _{incident light L 1} is irradiated to the flat sample 20 of the molded body at 0 ° perpendicular to the normal direction under the following measurement conditions. Distribution measurement was performed. The light receiving angle corresponds to the angle of the _{transmitted light L 2} with respect to the optical axis of _{the incident light L 1.}
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 the transmitted light was received at 5 °. JIS-Z-8781 from the spectral distribution data of transmitted light diffused in a direction forming an angle of 45 ° with respect to the horizontal direction from the normal direction of the molded body 20, that is, the spectral distribution data when the light receiving angle is 45 °. Each value of a *, b *, saturation C *, and hue h * when expressed in the CIE1976 color space was calculated by a method according to -4.
-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 °
・ Light reception end angle: 80 °
-Measurement pitch: 5 ° interval Next, the transparency of the flat sample 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.
Defective: The film was cloudy and poorly transparent.

[Manufacturing and evaluation of transparent screens]
As a transparent screen, the sheets and films produced in the above Examples and Comparative Examples were installed at a position 12 cm away from the image projection lens of an ultra-short throw projector (manufactured by Ricoh Co., Ltd., trade name: PJ WX4152). Next, an image was projected onto the screen from 60 ° below, and the focus knob of the projector was adjusted so that the position of the screen was in focus. Regarding the brightness uniformity of the projector image, the image visibility when observed from the front front, the image visibility when observed from an oblique 45 ° front 1 m, 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 light transmitted through the screen. The evaluation results are shown in Table 3 below.

[Evaluation criteria for image brightness uniformity]
Especially good: The brightness was very uniform when the screen image was viewed from any direction.
Good: The brightness was uniform when the screen image was viewed from any direction.
Defective: The brightness was uneven depending on the viewing angle of the screen image.
[Evaluation criteria for image color]
Especially good: The color reproducibility of the screen image was very high.
Good: The color reproducibility of the screen image was high.
Slightly poor: The screen image was bluish and the color reproducibility was slightly low.
Defective: The screen image had a strong bluish tint and the color reproducibility was low.

Claims (16)

A light diffusion molded product containing a transparent resin binder and light diffusion particles.
A flat sample of the light diffusion molded product is placed at a reference position, and the light diffusion molded product is placed at a reference position.
It is measured when incident light is irradiated toward the intersection of the vertical line and the flat surface sample along an incident axis inclined by 10 ° with respect to a vertical line perpendicular to the flat surface sample arranged at the reference position. A light diffusion molded body 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 flat sample.

(However, in the above formula (1),
D is the degree of diffusion,
I ₅ , I ₂₀ , and I ₇₀ are planes that include the perpendicular and are perpendicular to the plane sample at the reference position when the incident light of constant intensity is incident on the intersection. , On a virtual vertical plane perpendicular to the plane including the perpendicular and the incident axis, the angles θ with respect to the perpendicular are 5 °, 20 °, and 70 °, respectively, and from the intersection. The value of the relative transmitted light intensity of the transmitted light at the observation points where the distances are equal to each other is shown. ) From the spectral spectrum of transmitted light diffused in a direction forming an angle of 45 ° with respect to the plane sample when the plane sample placed at the reference position is irradiated with incident light along the perpendicular line, JIS- The first aspect of claim 1, wherein the values of a * and b * expressed in the CIE1976 color space calculated by a method based on Z-8781-4 satisfy the following conditions (i) and (ii). Light diffusion molded body.
(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. Claim 2 that the value of saturation C * expressed in the CIE1976 color space calculated by a method based on JIS-Z-8781-4 from the spectral spectrum of the transmitted light further satisfies the following condition (iii). The light diffusion molded body according to.
(Iii) C * is -10 or more and 10 or less. With respect to the transmitted light intensity of the reference transmitted light traveling along the perpendicular line through the plane sample arranged at the reference position when the incident light is irradiated to the intersection along the incident axis. _{Claim 1 in which the angle θ 1 of the} line passing through the intersection of the observation point on the vertical plane where the transmitted light having a relative transmitted light intensity of 1/2 is observed with respect to the perpendicular is 10.8 ° or more. The light diffusion molded body according to any one of 3 to 3. With respect to the transmitted light intensity of the reference transmitted light traveling along the perpendicular line through the plane sample arranged at the reference position when the incident light is irradiated to the intersection along the incident axis. Claims 1 to 3 that the _{angle θ 2 of the} line passing through the observation point on the vertical plane where the transmitted light having a relative transmitted light intensity of 1/10 is observed and the intersection is 30 ° or more. The light diffusion molded body according to any one of the above items. The light diffusion molded product according to any one of claims 1 to 5, wherein the value of the degree of diffusion D is 80 or less. An oxide, a composite oxide, and at least the oxide and the composite oxide of at least one element selected from the group consisting of Bi, Nd, Si, Al, Zr, and Ti in which the light diffusing particles are formed. The light diffusion molded product according to any one of claims 1 to 6, which comprises any one or more of any of the mixtures. The light diffusion according to claim 7, wherein the light diffusing particles contain at least one or more of an oxide of Bi, a composite oxide, and at least one mixture of the oxide and the composite oxide. Molded body. The light diffusion molded body according to any one of claims 1 to 8, wherein the Z average particle diameter of the light diffusion particles is 150 to 3500 nm. The light diffusion molded body according to any one of claims 1 to 9, wherein the value of the number average particle diameter of the light diffusing particles contained in the light diffusion molded body is 100 to 2300 nm. The item according to any one of claims 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 body is in the range of 300 to 2000 nm. The light diffusion molded body described. The light diffusion molded body according to any one of claims 1 to 11, which contains 0.001 to 3 parts by mass of the light diffusing particles with respect to 100 parts by mass of the transparent resin binder. The light diffusion molded body according to any one of claims 1 to 12, wherein the polydisperse index of the light diffusion particles is 0.8 or less. The light diffusion molded product according to any one of claims 1 to 13, wherein the transparent resin binder contains a thermoplastic resin. The light diffusion molded product according to claim 14, wherein the thermoplastic resin contains a polycarbonate resin. A film for a transparent screen containing the light diffusion molded product according to any one of claims 1 to 15.

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