Polarizing light filter
The invention is directed to a polarizer comprising an elongated element comprising a polyolefin, wherein the elongated element is unidirectionally drawn at a draw ratio within an overdrawing region and wherein the elongated element has a polarizing effect of at least 5%. The invention further relates to a method for producing said polarizer by drawing an undrawn or partially drawn elongated element within an overdrawing region and to particular uses and applications of said polarizer.
1 . A polarizer comprising an elongated element comprising a polyolefin, wherein the elongated element is unidirectionally drawn at a draw ratio within an overdrawing region and wherein the elongated element has a polarizing effect (PE) of at least 5% and less than 95%, wherein the polarizing effect is defined as the largest difference between light transmittance of two essentially orthogonally polarized components (Tmax and Tmin) of a visible light beam in accordance with the below Equation II.
PE
=
Tm
ax
-
Tmin
Tmax
*
1
0
0
%
(
Equation
II
)
2 . The polarizer according to claim 1 , wherein the elongated element
a) is a multilayered elongated element that comprises an inner layer and one or more outer layers, wherein the one or more outer layers weigh in between 1 to 50 wt % of the total weight of the elongated element;
b) is a multilayered elongated element that comprises an inner layer and one or more outer layers, which each independently comprise a polyolefin and wherein the inner layer and one or more outer layers each independently comprise a polymeric structure, wherein the polymeric structure of the one or more outer layers has a lower crystallinity than the polymeric structure of the inner layer;
c) comprises a polyolefin homopolymer and/or copolymer wherein the polyolefin is polypropylene and/or polyethylene;
d) comprises a yarn, a tape or a film having a thickness between 15 to 200 μm;
e) is unidirectionally drawn at a draw ratio of at least 20; and/or
f) has a tensile strength of at least 480 MPa.
3 . The polarizer according to claim 1 , wherein the polyolefin is a saturated polyolefin.
4 . The polarizer according to claim 1 , wherein the elongated element has a transmittance over the visible range of 380 to 700 nm of less than 80% as determined by UV-VIS-NIR spectrophotometry.
5 . The polarizer according to claim 1 , wherein the elongated element further comprises one or more pigments.
6 . The polarizer according to claim 1 , comprising a woven or non-woven fabric of a plurality of the elongated elements.
7 . The polarizer according to claim 6 , further comprising an essentially non-polarizing elongated element with a PE of at most 5%.
8 . The polarizer according to claim 6 , comprising at least a first polarizer having a first PE and at least a second polarizer having a second PE, wherein the first and second, PEs are different.
9 . The polarizer according to claim 1 , which is essentially free of dichroic dyes.
10 . The polarizer according to claim 1 , wherein the elongated element is produced without a dehydration stage or chemical reactions.
11 . Object obtainable by molding the polarizer according to claim 1 .
12 . Material comprising a matrix component reinforced with a polarizer according to claim 1 .
13 . Method for producing the polarizer according to claim 1 comprising providing an undrawn or partially drawn elongated element and subjecting the undrawn or partially drawn element to a single stage or multi-stage drawing at a draw ratio within an overdrawing region to obtain the elongated element.
14 . The method according to claim 13 , wherein the drawing is multi-stage drawing, wherein a first drawing stage is performed at a lower temperature than a second drawing stage and further comprising co-extrusion and/or lamination of an inner layer and one or more outer layers to provide an undrawn multilayered elongated element, wherein co-extrusion and/or lamination is performed in the presence of anti-oxidants, pigments and/or ultraviolet stabilizers.
15 . A product comprising a surface that comprises the polarizer according to claim 1 .
16 . The polarizer according to claim 1 , wherein the elongated element has a PE of between 5 and 50%.
17 . Use of a multilayered elongated element as a polarizer, wherein the multilayered elongated element comprises an inner layer and one or more outer layers each independently comprising a polyolefin, wherein the elongated element is unidirectionally drawn at a draw ratio within an overdrawing region and wherein the elongated element has a polarizing effect (PE) of at least 5% and less than 95%, wherein the maximum polarizing effect is defined as the largest difference between light transmittance of two essentially orthogonally polarized components (Tmax and Tmin) of a visible light beam in accordance with the Equation II below.
PE
=
Tm
ax
-
Tmin
Tmax
*
1
0
0
%
(
Equation
II
)
18 . Use of a multilayered elongated element as a polarizer in accordance with claim 17 in a fabric, which fabric comprises a plurality of parallel positioned polarizers with different PEs to provide a homogeneous appearance when illuminated by a linearly polarized light source perpendicular to the longitudinal axis of the polarizers, and a heterogenous appearance when illuminated by a linearly polarized light source parallel to the longitudinal axis of the polarizers.
19 . Use of a multilayered elongated element as a polarizer in accordance with claim 17 in a fabric, which fabric comprises a plurality of parallel and orthogonally positioned polarizers with different PEs to provide a first heterogenous appearance when illuminated by a linearly polarized light source in a particular direction, and a second heterogenous appearance when illuminated by a linearly polarized light source orthogonal to said particular direction.