JP2009223135A - Light-diffusing film and display member using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin and inexpensive display member capable of making light from a light source uniform and rendering a back face member or the light source invisible, in which a light-diffusing layer surface can be printed and other member for printing is unnecessary. <P>SOLUTION: A light-diffusing film is disclosed, which has a light-diffusing layer containing a binder resin and an inorganic light-diffusing agent, wherein the light-diffusing layer further contains metal oxide nanoparticles, and at least a part of the binder resin comprises a thermoplastic resin. The thermoplastic resin is preferably included by 65 to 85 wt.% of the binder resin. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a light diffusion film and a display member, and more particularly to a light diffusion film and a display member that uniformly diffuse light from an LED light source or the like.

  A display member having a light source on the back side of the display object diffuses light from the light source using a light diffusion film or the like, and makes the light from the light source uniform, or is on the back side of the light diffusion film such as the light source The member is not visually recognized.

  When such a light diffusing film is used in an optical application, it is important to improve the brightness of the front, and a number of members such as a liquid crystal cell, a polarizing film, and a prism lens are provided on the viewer side of the light diffusing film. Therefore, even if the light diffusibility of the light diffusing film is not so good, the pattern of the light guide plate, which is the light source and the back member, becomes difficult to visually recognize due to the large number of members arranged on the viewer side. For this reason, it is not necessary to make the light source or the light guide plate pattern completely invisible only by the light diffusion film, and even if the light diffusibility is not so good, it does not matter so much.

  On the other hand, when there are few members arranged on the viewer side than the light diffusion film, for example, when only a transparent plate or a printing member is arranged, as in the case of an electric signboard, a nameplate, a display unit of an audio device, etc. In addition, the transparent plate or printing member cannot hide the light source or substrate existing on the back of the light diffusion film, so light diffusion is important, and the light from the light source is made uniform and the back member and light source are visible. It is required to make it impossible.

  By using a light diffusion film that makes light from a light source uniform and emits light in a planar manner with an emphasis on light diffusivity in this way, a transparent plate or a printed member on which desired information is printed on the viewer side is provided. It can arrange | position and can be set as display members, such as an electrical signboard, a nameplate, and the display part of an audio equipment (patent document 1).

  In recent years, a display member having such a printed member disposed has been removed from the thickness and price reduction, and the printing member is eliminated, and the member to be printed serves as the light diffusion film, that is, printed on the light diffusion film. It is hoped that it can be done.

Japanese Patent Laid-Open No. 9-325717 (Prior Art, Problems to be Solved by the Invention)

  Therefore, an object of the present invention is to obtain a light diffusing film capable of making light from a light source uniform and further printing on the surface of the diffusing layer, and a display member using the same.

  As a result of earnest research to solve the above problems, in order to give the light diffusion film sufficient diffusibility, printing is performed on the surface of the diffusion layer of the light diffusion film using an inorganic light diffusion agent and metal oxide nanoparticles. Therefore, it has been found that the composition of the binder resin of the light diffusion layer and the metal oxide nanoparticles are included so that the light diffusion film has good printability, and this has been solved.

  That is, the light diffusing film of the present invention is a light diffusing film having a light diffusing layer containing a binder resin and an inorganic light diffusing agent, and the light diffusing layer further contains metal oxide nanoparticles, and the binder At least a part of the resin is a thermoplastic resin.

  The thermoplastic resin is 65 to 85% by weight of the binder resin. Furthermore, the light diffusing layer is printed.

  The display member of the present invention is characterized in that a light source is provided on the back surface of the light diffusion film described above, and planar light emission is performed by light transmitted through the light diffusion film.

  The light diffusion film of the present invention can make the light from the light source uniform so that the back member and the light source cannot be visually recognized, and can further print on the surface of the light diffusion layer. In addition, by using the light diffusing film of the present invention, since no other member for printing is required, a thin and inexpensive display member can be provided.

  An embodiment of the light diffusion film of the present invention will be described. The light diffusing film of the present invention is a light diffusing film having a light diffusing layer containing a binder resin and an inorganic light diffusing agent, and the light diffusing layer further contains metal oxide nanoparticles, At least a part is a thermoplastic resin.

  At least a part of the binder resin forming the light diffusion layer is a thermoplastic resin. Examples of the thermoplastic resin include polyethylene resin, polypropylene resin, cyclic olefin resin, ethylene / vinyl acetate copolymer resin, polyvinyl chloride resin, vinylidene chloride resin, polystyrene resin, methacrylic resin, and polyvinyl alcohol. Thermoplastic resins such as resin, polyamide resin, polyimide resin, ABS resin, and AS resin can be used.

  Thermosetting of polyurethane resin, unsaturated polyester resin, phenol resin, melamine resin, epoxy resin, silicone resin, polyester acrylate resin, polyurethane acrylate resin, epoxy acrylate resin, etc. as binder resin An ionizing radiation curable resin can also be mixed.

  The thermoplastic resin is preferably 65 to 85% by weight of the binder resin, and more preferably 70 to 80% by weight. The reason why the thermoplastic resin is 65% by weight or more is to obtain adhesiveness with the printing ink, and 85% by weight or less is to prevent deterioration of the light diffusion layer in a high-temperature and high-humidity environment. It is.

  As the inorganic light diffusing agent forming the light diffusing layer, inorganic fine particles such as silica, clay, talc, calcium carbonate, calcium sulfate, barium sulfate, aluminum silicate, titanium oxide, synthetic zeolite, alumina, smectite can be used. . In particular, calcium carbonate is preferable because it has a low oil absorption, can ensure light transmittance, and does not decrease the total light transmittance even in a high temperature and high humidity environment. The reason why the inorganic fine particles are used is that the light diffusibility is excellent as compared with the case where the organic fine particles are used, and the light diffusion effect can be obtained even with a small amount.

  The inorganic light diffusing agent is preferably 50 to 300 parts by weight, more preferably 100 to 200 parts by weight with respect to 100 parts by weight of the binder resin forming the light diffusing layer. The reason for setting it to 50 parts by weight or more is to obtain sufficient light diffusibility, to make the light from the light source uniform, and to prevent the viewer from seeing the back member and the light source. The reason why the content is 300 parts by weight or less is to prevent the coating film of the diffusion layer from becoming brittle.

  The average particle diameter of the inorganic diffusing agent cannot be generally specified depending on the thickness of the light diffusion layer, but is preferably 1 to 30 μm, and more preferably 1 to 10 μm.

  Furthermore, silica, titanium oxide, zirconium oxide, and zinc oxide can be used as the metal oxide nanoparticles contained in the light diffusion layer. Further, the light diffusibility can be improved by using the binder resin forming the light diffusion layer and the metal oxide nanoparticles having a large refractive index difference.

  Such metal oxide nanoparticles preferably have an average primary particle size of 1 to 50 nm. The reason why the particle size is 1 nm or more is that the oil absorption increases when the particle size is small, and the light diffusion layer becomes brittle unless the addition amount is small. The reason why the particle size is 50 nm or less is that when the particle size increases, This is because the gap due to the light diffusion agent cannot be filled.

  The metal oxide nanoparticles are preferably 5 to 20 parts by weight with respect to 100 parts by weight of the binder resin forming the light diffusion layer. 5 parts by weight or more can be achieved by adding metal oxide nanoparticles to smoothen the irregularities on the surface of the light diffusing layer, obtain adhesiveness with printing ink, pinholes and printing It is possible to improve the printability such as preventing the edge of the portion from being lost. Moreover, it is because a metal oxide nanoparticle can fill the space | gap by an inorganic type light-diffusion agent, and can aim at the improvement of light diffusibility. The reason why the content is 20 parts by weight or less is to prevent the light diffusion layer from becoming brittle.

  The thickness of the light diffusion layer is about 3 to 50 μm, preferably 30 μm or less, and more preferably 20 μm or less. The reason why the thickness is 3 μm or more is to obtain sufficient light diffusibility. The reason why the thickness is 50 μm or less is to reduce the thickness of the light diffusing film and reduce the thickness of the display member.

  The surface roughness of the light diffusion layer is preferably 0.05 to 2.00 μm in terms of arithmetic average roughness Ra (JIS B0601: 2001). By setting the thickness to 0.05 μm or more, it is possible to prevent the surface of the light diffusion layer from becoming a glossy surface and the printed information from becoming difficult to visually recognize. Moreover, by setting it as 2.00 micrometers or less, adhesiveness with printing ink can be acquired and it can prevent that the edge of a pinhole or a printing part is missing.

  The light diffusing layer described above is prepared by mixing each constituent component and other components as necessary, and dissolving or dispersing in an appropriate solvent to prepare a coating solution. It can be formed by applying and drying by a known method such as a method, a spray coating method, an air knife coating method, etc., and then suitably curing it using a necessary curing method.

  Such a light diffusion layer can be used alone or formed on a substrate to form a light diffusion film. As the base material, any material having a high transmittance may be used. For example, polyester resin, acrylic resin, acrylic urethane resin, polyester acrylate resin, polyurethane acrylate resin, epoxy acrylate resin, urethane resin, epoxy Resin, polycarbonate resin, cellulose resin, acetal resin, vinyl resin, polyethylene resin, polystyrene resin, polypropylene resin, polyamide resin, polyimide resin, melamine resin, phenol resin, silicone resin In addition, a polymer film having excellent transparency in which one or more of fluorine-based resin, cyclic olefin and the like are mixed is used. In particular, a biaxially stretched polyethylene terephthalate film can be suitably used because it is excellent in mechanical strength and dimensional stability. Moreover, what provided the easy-adhesion layer etc. suitably in these transparent polymer films is also used suitably. The thickness of the substrate is not particularly limited as long as it is a thickness that does not hinder the handling, but it is about 10 to 400 μm, preferably 12 to 350 μm.

  A back coat layer that prevents curling or scratches may be formed on the surface of the light diffusion film that is not provided with the light diffusion layer.

  In the light diffusion film of the present invention, the haze (JIS K7105: 1981) is preferably 85% or more. By setting it as such a range, while making the transmitted light from a light source uniform, it becomes easy to make a back surface member and a light source invisible. Further, the total light transmittance (JIS K7105: 1981) cannot be generally described depending on the distance from the light source, the required diffusibility and brightness, but is preferably 20 to 90%.

  A desired design and characters can be printed on the light diffusion film of the present invention by a conventionally known printing technique such as offset printing or silk screen printing. For example, by performing frame printing with opaque ink, the printed portion does not transmit light, and a display portion that emits light in a planar shape in a desired shape can be obtained. Also, it can be used for electrical signs and nameplates by printing designs and characters, and it can be used as a color filter for display parts of audio equipment by printing solid inks of various colors. it can.

  As the printing ink used for such printing, a two-component curable printing ink or a one-component curable printing ink that requires a curing agent such as isocyanate is used. Two-part curable printing inks tend to adhere even if there is little thermoplastic resin. However, such a two-part curable printing ink has a short usable time as a printing ink, cannot store and reuse an offset plate or a silk screen plate, and can clean a printing press. As a printing ink, it is preferable to use a one-component curable printing ink because it is difficult to perform.

  As described above, the light diffusing film of the present invention can convert light from a light source that emits light in a point or line shape into a planar light emission by providing a light source on the back surface, and performs desired printing on the light diffusing layer. Thus, a display member can be obtained.

  Next, an embodiment of the display member of the present invention will be described. In the display member of the present invention, a light source is provided on the back surface of the light diffusing film on which the above-described printing is performed, and the display portion emits light in a planar manner by light transmitted through the light diffusing film.

As a light source provided on the back surface of the light diffusion film, a hot cathode tube, a cold cathode tube, an LED or the like is mainly used. Examples of the shape of the light source include a dot shape, a line shape, and a U shape.
Even when such a light source is used, the light from the light source can be used as a planar light source by transmitting through the light diffusion film.

  The display member of the present invention is printed on the light diffusion layer surface of the light diffusion film by using a light diffusion film on which desired patterns and characters are printed by a conventionally known printing technique such as offset printing or silk screen printing. It is possible to reduce the thickness and the price without requiring a member.

  Such a display member may be provided with a protective plate for protecting the printing surface. Moreover, the polymer film used as a base material of a light-diffusion film can also be made into a surface protection film by arrange | positioning a printing surface in the light source side.

  Such a display member can be used for an electric signboard, a nameplate, and a display unit of an audio device. When the light source is turned on, the display portion emits light in a planar shape and can transmit desired information.

  The following examples further illustrate the present invention. “Parts” and “%” are based on weight unless otherwise specified.

1. Preparation of light diffusion film [Example 1]
A light diffusion layer coating solution having the following composition was applied by bar coating to one surface of a transparent polymer film (Lumirror T60: Toray Industries, Inc.) having a thickness of 100 μm, and heat cured to form a light diffusion layer having a thickness of about 11 μm. Further, a back coating layer coating solution having the following composition was applied to the opposite surface of the transparent polymer film to the light diffusion layer by bar coating, and cured by heating to form a coating film having a thickness of about 3 μm. A film was prepared.

<Light diffusion layer coating solution>
・ 56.25 parts of thermoplastic acrylic resin (Acridic A195: Dainippon Ink & Chemicals, Inc.)
(Solid content 40%)
・ Thermosetting acrylic resin 12.00 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Calcium carbonate 27.00 parts (Sunlite SL700: Takehara Chemical Industry Co., Ltd., average particle size 4.5 μm)
Silica fine particles 4.50 parts (Aerosil 200: Nippon Aerosil Co., Ltd., average particle diameter 12 nm)
-Diluting solvent 29.25 parts-Curing agent 2.50 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

<Backcoat layer coating solution>
・ Acrylic polyol 10 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
・ Polyethylene wax 0.022 parts (Celidust 3620, average particle size 8 μm: Clariant)
・ Dilute solvent 36 parts ・ Curing agent 2 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Example 2]
A light diffusing film of Example 2 was prepared in the same manner as in Example 1 except that the coating liquid for the light diffusion layer of Example 1 was replaced with the following coating liquid.

<Light diffusion layer coating solution>
-Thermoplastic acrylic resin 45.00 parts (Acridic A195: Dainippon Ink and Chemicals)
(Solid content 40%)
-Thermosetting acrylic resin 19.20 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Calcium carbonate 27.00 parts (Sunlite SL700: Takehara Chemical Industry Co., Ltd., average particle size 4.5 μm)
Silica fine particles 4.50 parts (Aerosil 200: Nippon Aerosil Co., Ltd., average particle diameter 12 nm)
・ Dilution solvent 31.80 parts ・ Curing agent 4.00 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Example 3]
A light diffusing film of Example 3 was prepared in the same manner as in Example 1 except that the coating liquid for the light diffusion layer of Example 1 was replaced with the following coating liquid.

<Light diffusion layer coating solution>
・ 52.50 parts of thermoplastic acrylic resin (Acridic A195: Dainippon Ink & Chemicals, Inc.)
(Solid content 40%)
-Thermosetting acrylic resin 14.40 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Calcium carbonate 27.00 parts (Sunlite SL700: Takehara Chemical Industry Co., Ltd., average particle size 4.5 μm)
Silica fine particles 4.50 parts (Aerosil 200: Nippon Aerosil Co., Ltd., average particle diameter 12 nm)
・ Diluting solvent 30.00 parts ・ Curing agent 3.00 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Example 4]
A light diffusing film of Example 4 was prepared in the same manner as in Example 1 except that the coating liquid for light diffusion layer of Example 1 was replaced with the following coating liquid.
<Light diffusion layer coating solution>
・ 63.75 parts of thermoplastic acrylic resin (Acridic A195: Dainippon Ink & Chemicals, Inc.)
(Solid content 40%)
-Thermosetting acrylic resin 7.20 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Calcium carbonate 27.00 parts (Sunlite SL700: Takehara Chemical Industry Co., Ltd., average particle size 4.5 μm)
Silica fine particles 4.50 parts (Aerosil 200: Nippon Aerosil Co., Ltd., average particle diameter 12 nm)
-Diluting solvent 27.55 parts-Curing agent 1.50 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Example 5]
A light diffusing film of Example 5 was prepared in the same manner as in Example 1 except that the coating liquid for the light diffusion layer of Example 1 was replaced with the following coating liquid.

<Light diffusion layer coating solution>
・ 67.50 parts of thermoplastic acrylic resin (Acridic A195: Dainippon Ink and Chemicals)
(Solid content 40%)
・ Thermosetting acrylic resin 4.80 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Calcium carbonate 27.00 parts (Sunlite SL700: Takehara Chemical Industry Co., Ltd., average particle size 4.5 μm)
Silica fine particles 4.50 parts (Aerosil 200: Nippon Aerosil Co., Ltd., average particle diameter 12 nm)
・ Diluting solvent 26.70 parts ・ Curing agent 1.00 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Example 6]
A light diffusing film of Example 6 was prepared in the same manner as in Example 1 except that the coating solution for the light diffusing layer in Example 1 was replaced with the following coating solution.

<Light diffusion layer coating solution>
-Thermoplastic acrylic resin 45.00 parts (Acryt 0502TC: Taisei Fine Chemical Co., Ltd.)
(Solid content 50%)
・ Thermosetting acrylic resin 12.00 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
・ 27.00 parts of calcium carbonate (Whiteon B: Shiraishi Calcium Co., Ltd., average particle size 3.6 μm)
Silica fine particles 4.50 parts (zirconium oxide PCS: NIPPON Denko, average particle size 20 nm)
-Diluting solvent 29.25 parts-Curing agent 2.50 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Comparative Example 1]
A light diffusing film of Comparative Example 1 was prepared in the same manner as in Example 1 except that the coating solution for the light diffusing layer in Example 1 was replaced with the following coating solution.

<Light diffusion layer coating solution>
・ Thermosetting acrylic resin 48.00 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Calcium carbonate 27.00 parts (Sunlite SL700: Takehara Chemical Industry Co., Ltd., average particle size 4.5 μm)
Silica fine particles 4.50 parts (Aerosil 200: Nippon Aerosil Co., Ltd., average particle diameter 12 nm)
・ Diluting solvent 42.00 parts ・ Curing agent 10.00 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Comparative Example 2]
A light diffusing film of Comparative Example 2 was prepared in the same manner as in Example 1 except that the coating liquid for the light diffusing layer in Example 1 was replaced with the following coating liquid.

<Light diffusion layer coating solution>
・ 56.25 parts of thermoplastic acrylic resin (Acridic A195: Dainippon Ink & Chemicals, Inc.)
(Solid content 40%)
・ Thermosetting acrylic resin 12.00 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
-Calcium carbonate 27.00 parts (Sunlite SL700: Takehara Chemical Industry Co., Ltd., average particle size 4.5 μm)
-Diluting solvent 29.25 parts-Curing agent 2.50 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Comparative Example 3]
A light diffusing film of Comparative Example 3 was prepared in the same manner as in Example 1 except that the coating liquid for the light diffusion layer in Example 1 was replaced with the following coating liquid.

<Light diffusion layer coating solution>
・ 56.25 parts of thermoplastic acrylic resin (Acridic A195: Dainippon Ink & Chemicals, Inc.)
(Solid content 40%)
・ Thermosetting acrylic resin 12.00 parts
(Acridic A807: Dainippon Ink & Chemicals, Inc.)
(Solid content 50%)
・ Organic fine particles 27.00 parts (Techpolymer MBX-5: Sekisui Plastics Co., Ltd., average particle size: 5.0 μm)
-Diluting solvent 29.25 parts-Curing agent 2.50 parts (Takenate D110N: Mitsui Chemicals Polyurethanes)
(Solid content 60%)

[Haze / total light transmittance]
About the light-diffusion film obtained in Examples 1-6 and Comparative Examples 1-3, according to JISK7105: 1981, using a haze meter (HGM-2K: Suga Test Instruments Co., Ltd.), a total light transmittance and haze are obtained. It was measured. In addition, about the measurement of the total light transmittance and haze, it measured by making light inject from the diffusion surface of a light-diffusion sheet. The results are shown in Table 1.

[Ink adhesion]
On the light diffusion layer of the light diffusion film obtained in Examples 1 to 6 and Comparative Examples 1 to 3, printing was performed with silk screen mesh # 200 using printing ink (SG700: Seiko Advance Co., Ltd.). The adhesiveness of the printing ink was evaluated by the tape method (JIS K5600-5-6: 1999). As a result of the peel test by the cross-cut tape method, “×” means that the cross-cut area is peeled off by 10% or more, and “x” means that a part of the cross-cut is peeled but the peel area is less than 10%. “△”, and “◯” means that the grid part did not peel at all. The results are shown in Table 1.

[Printability]
On the light diffusion layer of the light diffusion film obtained in Examples 1 to 6 and Comparative Examples 1 to 3, printing was performed with silk screen mesh # 200 using a printing ink (SG700: Seiko Advance), and pinholes The presence or absence of ink and the state of the edge of the printed part were observed. A case where a pinhole was generated or an edge of the printed portion was missing was indicated as “X”, and a case where no pinhole was generated and the edge of the printed portion was not missing was indicated as “◯”. The results are shown in Table 1.

[Light diffusivity]
An LED light source is installed at a position 5 mm from the center of the top surface of the box having an open top surface of 1 cm, and the light diffusion films obtained in Examples 1 to 6 and Comparative Examples 1 to 3 are arranged on the top surface of the box. Then, it was visually evaluated whether the LED light source can be visually recognized as a point. “X” indicates that the LED light source can be visually recognized as a dot, “○” indicates that the position of the LED light source is known, but does not cause a problem in practice, and “◎” indicates that the position of the LED light source cannot be visually recognized. It was. The results are shown in Table 1.

[High temperature and high humidity test]
Under an environment of 65 ° C. and 90% RH, changes in the total light transmittance of the light diffusion films obtained in Examples 1 to 6 and Comparative Examples 1 to 3 after 1000 hours were evaluated. “X” indicates that the change was 5% or more, “Δ” indicates that the change was 3% or more and less than 5%, and “◯” indicates that the change was less than 3%. The results are shown in Table 1.

  The light diffusing films of Examples 1 to 6 were excellent in diffusibility because the light diffusing layer contained a thermoplastic resin, an inorganic light diffusing agent, and metal oxide nanoparticles. Moreover, since the inorganic light diffusing agent and the metal oxide nanoparticles were included, the metal oxide nanoparticles were able to fill the gaps due to the inorganic light diffusing agent and smooth the uneven shape of the light diffusing layer.

  Therefore, the light diffusing films of Examples 1 to 6 have an arithmetic surface roughness of the light diffusing layer in the range of 1.0 to 1.5, and pinholes may be generated in the printed portion, or the edge of the printed portion may be Good printing was possible without chipping.

  Moreover, since the thermoplastic resin is 65 to 85% by weight of the binder resin in the light diffusing films of Examples 1, 3, 4, and 6, the printing ink adhesion is good and the results of the high-temperature and high-humidity test are also good. there were.

  Since the light diffusing film of Example 2 contained less thermoplastic resin in the binder resin, the light diffusing layer and the ink adhesion for printing were inferior to those of Example 1.

  In the light diffusing film of Example 5, since the thermoplastic resin is abundant in the binder resin, the adhesiveness between the base material and the light diffusing layer is inferior to that in Example 1, and therefore the adhesiveness of the printing ink is inferior. It was. Moreover, since there are many thermoplastic resins, the result of the high temperature, high humidity test became inferior.

  Since the light diffusion film of Example 6 used zirconium oxide fine particles as the metal oxide nanoparticles, the difference in refractive index with the binder resin of the light diffusion layer was large, so the haze was high and the light diffusion property was excellent. .

  The light diffusion film of Comparative Example 1 uses only a thermosetting resin for the light diffusion layer. Since it does not contain a thermoplastic resin, the printing ink adhesion cannot be obtained.

  The light diffusion film of Comparative Example 2 does not contain metal oxide nanoparticles. Since it does not contain metal oxide nanoparticles, it cannot fill the gap due to the inorganic light diffusing agent, and the uneven shape of the light diffusing layer cannot be smoothed, so the arithmetic surface roughness becomes 3.0 μm, and the pin Holes were generated and the edges of the printed part were missing. Further, since the gap cannot be filled, light diffusibility cannot be obtained as compared with the example.

  The light diffusing film of Comparative Example 3 uses organic fine particles instead of the inorganic light diffusing agent. Since organic fine particles were used, the diffusibility could not be obtained. In addition, since water enters the gap between the organic fine particles and the binder resin, the result of the high temperature and high humidity test is also poor. Furthermore, since the metal oxide nanoparticles were not included, the arithmetic surface roughness was 3.5 μm, pinholes were generated, and the edges of the printed part were missing.

  Next, an LED light source was installed at a position 5 mm from the center of the top surface of the box having an open top surface of 1 cm, and the light diffusing films of Examples 1 to 6 subjected to desired printing were disposed on the top surface of the box. Display members of Examples 1 to 6 were produced. In the display members of Examples 1 to 6, light from the light source was transmitted through the light diffusion film to emit planar light, and the brightness was uniform.

  Moreover, when it printed on the light-diffusion film of Examples 1-6 using the permeable ink, it was able to be set as the display member which functions as a color filter which has light diffusibility. Furthermore, when it printed using the impermeable ink, only the printing part was able to be set as the display member which has light-shielding property.

Claims (4)

  A light diffusing film having a light diffusing layer containing a binder resin and an inorganic light diffusing agent, wherein the light diffusing layer further contains metal oxide nanoparticles, and at least a part of the binder resin is a thermoplastic resin. A light diffusion film characterized by being.   The light diffusion film according to claim 1, wherein the thermoplastic resin is 65 to 85% by weight of the binder resin.   A light diffusing film, wherein the light diffusing layer of the light diffusing film according to claim 1 is printed. A light source is provided on the back surface of the light diffusing film according to claim 3, and planar light emission is performed by light transmitted through the light diffusing film.