Light diffusing films, methods of making the same, and articles using the same
View Patent ↗Disclosed herein are light diffusing films, methods of making the same and articles using the same. In one embodiment, a light diffusing film is formed from a composition comprising: a polycarbonate, phosphite stabilizer, epoxy stabilizer, hindered phenol stabilizer, and light diffusing particles having a refractive index of about 1.3 to about 1.7. The film comprises a hiding power of 0 to about 0.5. In one embodiment, a method for producing a film comprises combining a polycarbonate, a phosphite stabilizer, an epoxy stabilizer, and light diffusing particles to form a combination, and forming the combination into the film.
1. A light diffusing film,
wherein the film is formed from a composition comprising:
a polycarbonate, wherein the polycarbonate has a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E313-73 (D1925);
phosphite stabilizer;
epoxy stabilizer;
hindered phenol stabilizer; and
light diffusing particles having a refractive index of about 1.3 to about 1.7;
wherein weight percents are based upon a total weight of the composition; and
wherein the film comprises a hiding power of 0 to about 0.5 that is mathematically described by the following equation:
Hiding
power
(
%
)
=
1
-
∑
i
=
1
n
-
1
L
i
(
on
)
∑
j
=
1
n
-
1
L
j
(
off
)
×
100
wherein: L i (on) is luminance above i th cold cathode fluorescent lamp, L i (off) is luminance at a midpoint between cold cathode fluorescent lamp j and cold cathode fluorescent lamp j+1, and n equals number of CCFL lamps; and
wherein the light diffusing film has a 13 points average luminance that is greater than a 13 points average luminance of a polycarbonate film, as determined by a 13 points test using a Topcon BM-7 instrument, wherein the polycarbonate film comprises about 3.5 wt % acrylate particles based on a total weight of the polycarbonate film, and the polycarbonate film has a thickness of 2 millimeters and a transmission of 50.4% as determined in accordance with ASTM D1003-00 and as measured with instrument Macbeth 7000A, D65 light source illuminant, 10° observer.
2. The light diffusing film of claim 1 , wherein the composition comprises about 0.005 wt % to about 0.06 wt % epoxy stabilizer.
3. The light diffusing film of claim 1 , wherein the composition comprises about 0.015 wt % to about 0.04 wt % epoxy stabilizer, about 0.04 wt % to about 0.09 wt % phosphite stabilizer, and about 0.001 wt % to about 7 wt % light diffusing particles.
4. The light diffusing film of claim 1 , wherein the composition comprises about 0.015 wt % to about 0.03 wt % epoxy stabilizer, about 0.01 wt % to about 0.03 wt % hindered phenol stabilizer, and about 0.04 wt % to about 0.09 wt % phosphite stabilizer.
5. The light diffusing film of claim 1 , wherein the composition comprises about 0.04 wt % to about 0.09 wt % phosphite stabilizer.
6. The light diffusing film of claim 1 , wherein the composition comprises about 0.005 wt % to about 0.06 wt % hindered phenol stabilizer.
7. The light diffusing film of claim 1 , wherein the composition comprises about 0.01 wt % to about 0.04 wt % hindered phenol stabilizer.
8. The light diffusing film of claim 1 , wherein the light diffusing particles comprise a material selected from the group consisting of silsesquioxanes, fluorinated polymers, homopolymers formed from styrene, copolymers formed from styrene, acrylic acid, metal sulfates, metal oxides, metal hydroxides, metal carbonates, metal silicates, and combinations comprising at least one of the foregoing.
9. The light diffusing film of claim 8 , wherein the material comprises polyorgano silsesquioxane.
10. The light diffusing film of claim 1 , wherein the light diffusing particles comprise a material are selected from the group consisting of poly(styrene), poly(acrylic acid), poly(methyl methacrylate), poly(acrylic acid-styrene) copolymers, poly(C 1-8 alkylacrylate-C 1-8 alkylmethacrylate) copolymers, and combinations comprising at least one of the foregoing.
11. The light diffusing film of claim 10 , wherein the material comprises poly(methyl methacrylate)-polystyrene copolymer.
12. The light diffusing film of claim 1 , wherein the virgin polycarbonate was produced by an interfacial reaction.
13. A light diffusing film formed in accordance with the method comprising:
combining about 90 wt % to about 99.9 wt % polycarbonate, about 0.04 wt % to about 0.09 wt % phosphite stabilizer, about 0.015 wt % to about 0.03 wt % epoxy stabilizer, about 0.01 wt % to about 0.03 wt % hindered phenol stabilizer and light diffusing particles to form a combination, wherein the light diffusing particles have a refractive index of about 1.3 to about 1.7; and
forming the combination into the light diffusing film;
wherein the light diffusing film comprises a hiding power of 0 to about 0.5 that is mathematically described by the following equation:
Hiding
power
(
%
)
=
1
-
∑
i
=
1
n
-
1
L
i
(
on
)
∑
j
=
1
n
-
1
L
j
(
off
)
×
100
wherein: L i (on) is luminance above i th cold cathode fluorescent lamp, L j (off) is luminance at a midpoint between cold cathode fluorescent lamp j and cold cathode fluorescent lamp j+1, and n equals number of CCFL lamps;
wherein the polycarbonate is virgin polycarbonate powder which has not been heat processed, and which has a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E313-73 (D1925).
14. The light diffusing film of claim 13 , wherein the light diffusing film has a 13 points average luminance that is greater than a polycarbonate film 13 points average luminance, as determined by a 13 points test using a Topcon BM-7 instrument, wherein at the polycarbonate film comprises about 3.5 wt % acrylate particles based on a total weight of the polycarbonate film, and the polycarbonate film has a thickness of 2 millimeters and a transmission of 50.4% as determined in accordance with ASTM D1003-00 and as measured with instrument Macbeth 7000A, D65 light source illuminant, 10° observer.
15. A display device, comprising:
a liquid crystal display;
a light source disposed in optical communication with the liquid crystal display; and
a light diffusing film disposed between the liquid crystal display and the light source, wherein the light diffusing film comprises a polycarbonate, a phosphite stabilizer, an epoxy stabilizer, and light diffusing particles having a refractive index of about 1.3 to about 1.7; and
wherein the light diffusing film comprises a hiding power of 0 to about 0.5 that is mathematically described by the following equation:
Hiding
power
(
%
)
=
1
-
∑
i
=
1
n
-
1
L
i
(
on
)
∑
j
=
1
n
-
1
L
j
(
off
)
×
100
wherein: L i (on) is luminance above i th cold cathode fluorescent lamp, L j (off) is luminance at a midpoint between cold cathode fluorescent lamp j and cold cathode fluorescent lamp j+1, and n equals number of CCFL lamps; and
wherein the light diffusing film has a 13 points average luminance that is greater than a 13 points average luminance of a polycarbonate film, as determined by a 13 points test using a Topcon BM-7 instrument, wherein the polycarbonate film comprises about 3.5 wt % acrylate particles based on a total weight of the polycarbonate film, and the polycarbonate film has a thickness of 2 millimeters and a transmission of 50.4% as determined in accordance with ASTM D1003-00 and as measured with instrument Macbeth 7000A, D65 light source illuminant, 10° observer.
16. A light diffusing film, comprising the reaction product of:
about 90 wt % to about 99.9 wt % virgin polycarbonate powder which has not been heat processed, and which has a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E313-73 (D1925);
about 0.04 wt % to about 0.09 wt % phosphite stabilizer;
about 0.015 wt % to about 0.03 wt % epoxy stabilizer;
about 0.01 wt % to about 0.03 wt % hindered phenol stabilizer; and
about 0.001 wt % to about 10 wt % light diffusing particles having a refractive index of about 1.3 to about 1.7;
wherein the weight percentages are based upon a total weight of ingredients combined prior to any reaction; and
wherein the film comprises a hiding power of 0 to about 0.5 that is mathematically described by the following equation:
Hiding
power
(
%
)
=
1
-
∑
i
=
1
n
-
1
L
i
(
on
)
∑
j
=
1
n
-
1
L
j
(
off
)
×
100
wherein: L j (on) is luminance above i th cold cathode fluorescent lamp, L i (off) is luminance at a midpoint between cold cathode fluorescent lamp j and cold cathode fluorescent lamp j+1, and n equals number of CCFL lamps.
17. A light diffusing film,
wherein the film is formed from a composition comprising:
virgin polycarbonate powder which has not been heat processed, wherein the virgin polycarbonate has a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E313-73 (D1925);
phosphite stabilizer;
epoxy stabilizer;
hindered phenol stabilizer;
optical brightener; and
light diffusing particles having a refractive index of about 1.3 to about 1.7; and
wherein the film comprises a hiding power of 0 to about 0.5 that is mathematically described by the following equation:
Hiding
power
(
%
)
=
1
-
∑
i
=
1
n
-
1
L
i
(
on
)
∑
j
=
1
n
-
1
L
j
(
off
)
×
100
wherein: L j (on) is luminance above i th cold cathode fluorescent lamp, L i (off) is luminance at a midpoint between cold cathode fluorescent lamp j and cold cathode fluorescent lamp j+1, and n equals number of CCFL lamps;
wherein the light diffusing film has a 13 points average luminance that is greater than a 13 points average luminance of a polycarbonate film, as determined by a 13 points test using a Topcon BM-7 instrument, wherein the polycarbonate film comprises about 3.5 wt % acrylate particles based on a total weight of the polycarbonate film, and the polycarbonate film has a thickness of 2 millimeters and a transmission of 50.4% as determined in accordance with ASTM D1003-00 and as measured with instrument Macbeth 7000A, D65 light source illuminant, 10° observer.
18. The light diffusing film of claim 17 , wherein the light diffusing particles comprise polymethyl silsesquioxane.
19. The light diffusing film of claim 17 , wherein the composition comprises about 0.001 wt % to about 3.0 wt % optical brighteners, based on a total weight of the light diffusing film.
20. The light diffusing film of claim 17 , wherein the optical brightener is selected from the group consisting of derivatives of 4,4′bis(2-benzoxazolyl)stilbene, 4,4′- diaminostilbene-2,2′-disulfonic acid, and coumarin derivatives.
21. A light diffusing film,
wherein the light diffusing film is formed from a composition comprising:
a polycarbonate, wherein the polycarbonate comprises no dyes or colorants and has a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E313-73 (D1925);
phosphite stabilizer;
epoxy stabilizer;
hindered phenol stabilizer; and
light diffusing particles having a refractive index of about 1.3 to about 1.7; and
wherein the light diffusing film comprises a hiding power of 0 to about 0.5 that is mathematically described by the following equation:
Hiding
power
(
%
)
=
1
-
∑
i
=
1
n
-
1
L
i
(
on
)
∑
j
=
1
n
-
1
L
j
(
off
)
×
100
wherein : L i (on) is luminance above i th cold cathode fluorescent lamp, L j (off) is luminance at a midpoint between cold cathode fluorescent lamp j and cold cathode fluorescent lamp j+1, and n equals number of CCFL lamps; and
wherein the light diffusing film has a 13 points average luminance that is greater than a 13 points average luminance of a polycarbonate film, as determined by a 13 points test using a Topcon BM-7 instrument, wherein the polycarbonate film comprises about 3.5 wt % acrylate particles based on a total weight of the polycarbonate film, and the polycarbonate film has a thickness of 2 millimeters and a transmission of 50.4% as determined in accordance with ASTM D1003-00 and as measured with instrument Macbeth 7000A, D65 light source illuminant, 10° observer.
22. A light diffusing film,
wherein the film is formed from a composition comprising:
about 90 wt % to about 99.9 wt % polycarbonate;
about 0.04 wt % to about 0.09 wt % phosphite stabilizer;
about 0.015 wt % to about 0.03 wt % epoxy stabilizer;
about 0.01 wt % to about 0.03 wt % hindered phenol stabilizer; and
about 0.001 wt % to about 10 wt % light diffusing particles, wherein the light diffusing particles comprise polyorgano silsesquioxane;
wherein weight percents are based upon a total weight of the composition; and
wherein the film comprises a hiding power of 0 to about 0.5 that is mathematically described by the following equation:
Hiding
power
(
%
)
=
1
-
∑
i
=
1
n
-
1
L
i
(
on
)
∑
j
=
1
n
-
1
L
j
(
off
)
×
100
wherein: L i (on) is luminance above i th cold cathode fluorescent lamp, L j (off) is luminance at a midpoint between cold cathode fluorescent lamp j and cold cathode fluorescent lamp j+1, and n equals number of CCFL lamps; and wherein:
(i) The light diffusing film has a 13 points average luminance that is greater than a 13 points average luminance of a polycarbonate film, as determined by a 13 points test using a Topcon BM-7 instrument, wherein said polycarbonate film comprises about 3.5 wt % acrylate particles based on a total weight of the polycarbonate film, and the polycarbonate film has a thickness of 2 millimeters and a transmission of 50.4%, as determined in accordance with ASTM D1003-00 and as measured with instrument Macbeth 7000A, D65 light source illuminant, 10° observer; or p 1 (ii) The polycarbonate is virgin polycarbonate powder which has not been heat processed, and which has a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E 313-73 (D1925); or
(iii) The polycarbonate comprises no dyes or colorants and has a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E313-73 (D1925).