LIGHT DIFFUSING FILM AND PROCESS FOR PRODUCING THE LIGHT DIFFUSING FILM

• US 20110019279A1
• Filed: 12/08/2008
• Published: 01/27/2011
• Est. Priority Date: 03/12/2008
• Status: Abandoned Application

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Miyatake, Minoru, Nishimura, Akinori, Yonezawa, Hideyuki
• Application Number:
  US12/921,047
• Publication Number:
  US 20110019279A1
• Time in Patent Office: Days
• US Class Current: 359/599
• CPC Class Codes: G02B 5/0242 by means of dispersed particles
• CPC Class Codes: G02B 5/0268 characterized by the fabrication or manufacturing method
• CPC Class Codes: G02B 5/0289 used as a transflector

Abstract

A light diffusing film having superior productivity can be obtained by using very short fibers as a substitute for conventional spherical fine particles as light diffusing material. It is possible to mass-produce very short fibers at low cost, for example, by cutting fibers. Further, it is relatively easy to obtain very short fibers with a narrow fiber length distribution. The use of this makes it possible to carry out more highly sophisticated optical design of light diffusing films.

Claims

1. A light diffusing film comprising:

a film made of a translucent resin; and

a plurality of very short fibers dispersed in the film made of a translucent resin, wherein an average refractive index n_A of the translucent resin is different from an average refractive index n_B of the very short fibers when the average refractive index n_A of the translucent resin is defined as (extraordinary refractive index+2×

ordinary refractive index)/3 and the average refractive index n_B of the very short fibers is defined as (refractive index in the direction of a major axis+2×

refractive index in the direction of a minor axis)/3.

2. The film according to claim 1, wherein the average refractive index n_A of the translucent resin is 1.3 to 1.7 and the average refractive index n_B of the very short fibers is 1.4 to 1.6, and an absolute value of the difference between the average refractive index n_A of the translucent resin and the average refractive index n_B of the very short fibers, |n_A−

n_B| is 0.005 to 0.15.

6. The film according to claim 1, comprising:

a film made of a translucent resin;

a plurality of very short fibers dispersed in the film made of a translucent resin; and

a plurality of spherical fine particles dispersed in the film made of a translucent resin,

wherein an average refractive index of the translucent resin is different from an average refractive index of the very short fibers and a refractive index of the spherical fine particles.

8. The film according to claim 2, comprising:

a film made of a translucent resin;

a plurality of very short fibers dispersed in the film made of a translucent resin; and

a plurality of spherical fine particles dispersed in the film made of a translucent resin,

wherein an average refractive index of the translucent resin is different from an average refractive index of the very short fibers and a refractive index of the spherical fine particles.

9. A process for producing the light diffusing film according to any one of claims 1 to 6 and 8, comprising the steps of:

A) dispersing a plurality of very short fibers obtained by cutting fibers in a liquid material which forms a film made of a translucent resin to obtain a dispersion liquid; and

B) casting the dispersion liquid obtained in the step A in a film and solidifying or curing a cast layer thereof to obtain a light diffusing film.

3. A light diffusing film comprising:

a film made of a translucent resin; and

a plurality of very short fibers dispersed in the film made of a translucent resin, each of which has a first refractive index region and a second refractive index region provided within the first refractive index region, wherein an average refractive index n_A of the translucent resin is different from an average refractive index n_B2 of the very short fibers in the second refractive index region when the average refractive index n_B2 of the very short fibers in the second refractive index region is defined as (refractive index in the direction of a major axis+2×

refractive index in the direction of a minor axis)/3.

4. The film according to claim 3, wherein the average refractive index n_A of the translucent resin is 1.3 to 1.7 and an absolute value of the difference between the average refractive index n_A of the transparent resin and the average refractive index n_B2 of the very short fibers in the second refractive index region, |n_A−

n_B2| is 0.01 to 0.15.

5. The film according to claim 3, wherein the average refractive index n_A of the translucent resin, an average refractive index n_B1 of the very short fibers in the first refractive index region, and the average refractive index n_B2 of the very short fibers in the second refractive index region satisfies the relationship:

n_A<

n_B1<

n_B2 or n_B2<

n_B1<

n_A when the average refractive index n_B1 of the very short fibers in the first refractive index region is defined as (refractive index in the direction of a major axis+2×

refractive index in the direction of a minor axis)/3.

7. (canceled)