LIGHT DIFFUSING FILMS, METHODS OF MAKING THE SAME, AND ARTICLES USING THE SAME
Disclosed herein are light diffusing films, methods of making the same and articles using the same. In one embodiment, a method of making a light-diffusing film comprises: mixing about 90 wt. % to about 99.999 wt. % of a powdered polycarbonate and about 0.001 wt. % to about 3 wt. % light-diffusing particles to form a mixture, wherein weight percents are based on a total weight of the light-diffusing film; melting the mixture to form a melt; and extruding the melt in the form of a sheet to form the light-diffusing film. The light-diffusing film comprises a hiding power of about 0 to 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.
1 . A method of making a light-diffusing film comprising:
mixing about 90 wt. % to about 99.999 wt. % of a powdered polycarbonate and about 0.001 wt. % to about 3 wt. % light-diffusing particles to form a mixture, wherein weight percents are based on a total weight of the light-diffusing film;
melting the mixture to form a melt; and
extruding the melt in the form of a sheet to form the light-diffusing film;
wherein the light-diffusing film comprises a hiding power of about 0 to 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 comprises 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, 100 observer.
2 . A method of making a light-diffusing film comprising:
mixing a powdered polycarbonate and light-diffusing particles to form a mixture;
melting the mixture to form a melt; and
extruding the melt in the form of a sheet to form the light-diffusing film;
wherein the light-diffusing film comprises a light transmission of about 45% to about 65% as measured according to ASTM D1003-00;
wherein the light-diffusing film comprises a hiding power of about 0 to 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 comprises 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, 100 observer.
3 . The method of claim 2 , wherein the polycarbonate comprises a yellowness index of about 0.8 to about 1.5 as measured in accordance with ASTM E313-73 (D1925).
4 . The method of claim 3 , wherein the yellowness index is about 0.8 to about 1.3.
5 - 18 . (canceled)