Light-scattering substrate, method for manufacturing light-scattering substrate, polarizing plate and image display device

• US 8,643,808 B2
• Filed: 04/29/2010
• Issued: 02/04/2014
• Est. Priority Date: 04/30/2009
• Status: Active Grant

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Watanabe, Jun, Yoneyama, Hiroyuki, Abiru, Daisaku, Ohashi, Yusuke
• Primary Examiner(s): Hahm, Sarah
• Application Number:
  US12/662,706
• Publication Number:
  US 20100277674A1
• Time in Patent Office: 1,377 Days
• Field of Search: None
• US Class Current: 349/96
• CPC Class Codes: B29C 39/148 characterised by the shape of the surface
• CPC Class Codes: B29C 39/20 Making multilayered or multicoloured articles B29C39/142 takes precedence
• CPC Class Codes: B29K 2105/16 Fillers
• CPC Class Codes: B29K 2995/0018 having particular optical properties, e.g. fluorescent or phosphorescent
• CPC Class Codes: G02B 5/02 Diffusing elements; Afocal elements
• CPC Class Codes: G02B 5/3033 in the form of a thin sheet or foil, e.g. Polaroid

Abstract

A light-scattering substrate having an irregular shape on one surface thereof is provided, the light-scattering substrate including: a thermoplastic resin; and at least one kind of transparent particles having a mean primary particle size of 3 μm or more and not more than 12 μm, wherein the light-scattering substrate contains a first region having a thickness of ½ or more times and not more than 4 times the mean primary particle size of the transparent particles from the surface having an irregular shape; and a second region having a thickness of 3/2 or more times the mean primary particle size of the transparent particles from a surface on back side of the surface having an irregular shape, and the first region and the second region have a region not substantially containing the transparent particle.

Claims

1. A light-scattering substrate having an irregular shape on one surface thereof, the light-scattering substrate comprising:

a thermoplastic resin; and

at least one kind of transparent particles having a mean primary particle size of 3 μ

m or more and not more than 12 μ

m,

wherein the light-scattering substrate contains a first region having a thickness of ½

or more times and not more than 4 times the mean primary particle size of the transparent particles from the surface having an irregular shape; and

a second region having a thickness of 3/2 or more times the mean primary particle size of the transparent particles from a surface on back side of the surface having an irregular shape,

wherein the first region and the second region have a region not substantially containing the transparent particles, and

wherein a tilt angle of irregularities of the surface of the light-scattering substrate having an irregular shape has the following distribution;

(a) an integrated value of the frequency of 0°

or more and less than 0.5°

is less than 25%;

(b) an integrated value of the frequency of 0.5°

or more and less than 10°

is 65% or more and less than 100%; and

(c) an integrated value of the frequency of 10°

or more is 0% or more and less than 20%.

2. The light-scattering substrate according to claim 1,

wherein the surface of the light-scattering substrate having an irregular shape has an arithmetic mean roughness Ra, a mean spacing of irregularities Sm and a mean tilt angle of irregularities θ

a in conformity with JIS B0601, which are satisfied with following expressions (1) to (3);

0.03 μ

m≦

Ra≦

0.3 μ

m 

 

(1)

10 μ

m≦

Sm≦

300 μ

m 

 

(2)

0.2°

≦

θ

a≦

2.5°

 

 

(3).

3. The light-scattering substrate according to claim 1,

wherein the transparent particles are substantially spherical resin particles.

4. The light-scattering substrate according to claim 1,

wherein an absolute value of a difference between a refractive index of the transparent particles and a refractive index of the light-scattering substrate in the case of excluding the transparent particles from the light-scattering substrate is less than 0.09.

5. The light-scattering substrate according to claim 1, which has light scattering properties such that a value of an image clarity measured through an optical comb having a width of 2 mm by using an image clarity measuring apparatus in conformity with JIS K7105 is from 5% to 60%.

6. The light-scattering substrate according to claim 1,

wherein a transmitted scattered-light profile measured by a goniophotometer with an acceptance angle of 2°

is satisfied with following expression (d);

0.03≦

I(4°

)/I0≦

0.07 

 

(d)

wherein I(4°

) represents an transmitted light intensity at a position tilted by 4°

from a normal line of the light-scattering substrate; and

I0 represents a light intensity when a light source is measured from the front.

7. The light-scattering substrate according to claim 1,

wherein a haze value caused by inside is 0.1% or more and less than 30%;

and a haze value caused by surface is 3% or more and less than 30%.

8. The light-scattering substrate according to claim 1, wherein a main component of the light-scattering substrate is the thermoplastic resin selected from the group consisting of triacetyl cellulose, diacetyl cellulose, acetyl butyryl cellulose, propionyl cellulose, polycarbonate, and modified polymethyl methacrylate.

9. A polarizing plate, comprising:

a polarizing film; and

a protective film on or above at least one side of the polarizing film,

wherein the protective film is the light-scattering substrate according to claim 1.

10. An image display device, comprising:

the light-scattering substrate according to claim 1.

11. An image display device, comprising:

a light source;

a lower polarizing plate;

a liquid crystal cell; and

an upper polarizing plate in this order,

wherein the lower polarizing plate is the polarizing plate according to claim 9.

12. A light-scattering substrate having an irregular shape on one surface thereof, the light-scattering substrate comprising:

a thermoplastic resin; and

at least one kind of transparent particles having a mean primary particle size of 3 μ

m or more and not more than 12 μ

m,

wherein the light-scattering substrate contains a first region having a thickness of ½

or more times and not more than 4 times the mean primary particle size of the transparent particles from the surface having an irregular shape; and

a second region having a thickness of 3/2 or more times the mean primary particle size of the transparent particles from a surface on back side of the surface having an irregular shape,

wherein the first region and the second region have a region not substantially containing the transparent particles, and

which has light scattering properties such that a value of an image clarity measured through an optical comb having a width of 2 mm by using an image clarity measuring apparatus in conformity with JIS K7105 is from 5% to 60%.

13. A polarizing plate, comprising:

a polarizing film; and

a protective film on or above at least one side of the polarizing film,

wherein the protective film is the light-scattering substrate according to claim 12.

14. An image display device, comprising:

the light-scattering substrate according to claim 12.

15. An image display device, comprising:

a light source;

a lower polarizing plate;

a liquid crystal cell; and

an upper polarizing plate in this order,

wherein the lower polarizing plate is the polarizing plate according to claim 13.

16. A light-scattering substrate having an irregular shape on one surface thereof, the light-scattering substrate comprising:

a thermoplastic resin; and

at least one kind of transparent particles having a mean primary particle size of 3 μ

m or more and not more than 12 μ

m,

wherein the light-scattering substrate contains a first region having a thickness of ½

or more times and not more than 4 times the mean primary particle size of the transparent particles from the surface having an irregular shape; and

a second region having a thickness of 3/2 or more times the mean primary particle size of the transparent particles from a surface on back side of the surface having an irregular shape,

wherein the first region and the second region have a region not substantially containing the transparent particles,

wherein a transmitted scattered-light profile measured by a goniophotometer with an acceptance angle of 2°

is satisfied with following expression (d);

0.03≦

I(4°

)/I0≦

0.07 

 

(d), and

wherein I(4°

) represents an transmitted light intensity at a position tilted by 4°

from a normal line of the light-scattering substrate; and

I0 represents a light intensity when a light source is measured from the front.

17. A polarizing plate, comprising:

a polarizing film; and

a protective film on or above at least one side of the polarizing film,

wherein the protective film is the light-scattering substrate according to claim 16.

18. An image display device, comprising:

the light-scattering substrate according to claim 16.

19. An image display device, comprising:

a light source;

a lower polarizing plate;

a liquid crystal cell; and

an upper polarizing plate in this order,

wherein the lower polarizing plate is the polarizing plate according to claim 17.