Stock material or miscellaneous articles – Structurally defined web or sheet – Including components having same physical characteristic in...
Reexamination Certificate
1999-10-18
2001-12-11
Dixon, Merrick (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including components having same physical characteristic in...
C428S156000, C428S170000
Reexamination Certificate
active
06329046
ABSTRACT:
BACKGROUND
This invention relates generally to an optical film and a process for manufacture thereof, and more particularly to processes in which the properties of materials in the film are exploited to control the response of the materials during processing.
Over the past several years the use of polymeric films to produce high-quality optical films has been explored. The investigated polymeric optical films typically exploit differing indices of refraction between layers of a multilayer film. For example, a multilayer optical film may be constructed by alternating polymer layers having high indices of refraction with polymer layers having low indices of refraction. Where two adjacent layers are formed with a relatively large mismatch between the respective indices of refraction, light of a particular wavelength is reflected at the interface of the two layers. The wavelength of light reflected is dependent on the optical thickness of the adjacent layers. Optical films may also be made of polymeric blends exploiting relative refractive indices relationships of different phases of the blend.
One type of multilayer optical film uses birefringent polymers to produce the mismatch between adjacent indices of refraction. In such films, the multilayer film is drawn either uniaxially in a direction along only one in-plane axis of the film or biaxially in a direction along two in-plane orthogonal axes of the film. As a result of drawing, molecules within one of the two adjacent layers become oriented in the direction of the draw. The molecular orientation alters the index of refraction of the affected layer in the draw direction.
Drawing a multilayer film, where one of the layers of the film is birefringent, can be used to obtain a mismatch of refractive indices of two adjacent layers in the draw direction. If the refractive indices of the two layers in the non-drawn in-plane direction match, the multilayer film may be used to reflect light of one polarization and transmit light of another. Such a film may be employed, for example, as a reflective polarizer. If a multilayer film is drawn such that the affected layer is oriented in the direction of two orthogonal in-plane axes, a mismatch in both directions may be obtained. Such a film may be used to reflect light of both polarizations (e.g., a mirror for the respective wavelength of light).
As noted above, one or more of the materials used in polymeric optical films has optical characteristics which change as the material is drawn. These characteristics tend to assume a directional orientation which depends on the direction in which the material is drawn. Such optical films may be described in terms of three mutually orthogonal axes, namely, two in-plane axes x and y and a thickness axis z. The optical properties of such optical films depend generally on the indices of refraction n
x
, n
y
and n
z
of each material in the direction of the x, y and z axes, respectively. Thus, it is desirable to process the optical film in a manner which permits precise control over the optical properties of the materials used.
SUMMARY
Generally, the present invention relates to optical films and processes for manufacture thereof. In accordance with one embodiment of the invention an optical film, including at least a first and second material, is made by processing the film with respect to first and second in-plane axes of the film under conditions which induce optical-orientation in at least the first material along the first in-plane axis of the film while inducing orientation in the first material along the second in-plane axis of the film which is substantially less than the orientation induced along the first axis. The refractive index of the second material substantially matches the refractive index of the first material along one of the first and second in-plane axes of the film.
The process may be used to make films having improved optical and/or mechanical performance. The process may be used to make a number of different films. Two or more materials of the film may form alternating layers in a multilayer optical film. The two materials may also be formed in a blend film, for example, as a continuous phase and a disperse phase of material. In accordance with one embodiment of the invention, various combinations of orientation states of the two materials may be obtained by controlling the response of the materials to draw processing conditions.
The above summary of the present invention is not intended to describe each illustrated embodiment or every implementation of the present invention. The figures and the detailed description which follow more particularly exemplify these embodiments.
REFERENCES:
patent: 2158130 (1939-05-01), Land
patent: 2997390 (1961-08-01), Land
patent: 3124639 (1964-03-01), Kahn
patent: 3610729 (1971-10-01), Rogers
patent: 3711176 (1973-01-01), Alfrey, Jr. et al.
patent: 3860036 (1975-01-01), Newman, Jr.
patent: 4446305 (1984-05-01), Rogers et al.
patent: 4520189 (1985-05-01), Rogers et al.
patent: 4521588 (1985-06-01), Rogers et al.
patent: 4525413 (1985-06-01), Rogers et al.
patent: 4720426 (1988-01-01), Englert et al.
patent: 5188760 (1993-02-01), Hikmet et al.
patent: 5211878 (1993-05-01), Reiffenrath et al.
patent: 5235443 (1993-08-01), Barnik et al.
patent: 5269995 (1993-12-01), Ramanathan et al.
patent: 5294657 (1994-03-01), Melendy et al.
patent: 5316703 (1994-05-01), Schrenk
patent: 5319478 (1994-06-01), Fijnfschilling et al.
patent: 5389324 (1995-02-01), Lewis et al.
patent: 5448404 (1995-09-01), Schrenk et al.
patent: 5486935 (1996-01-01), Kalmanash
patent: 5486949 (1996-01-01), Schrenk et al.
patent: 5612820 (1997-03-01), Schrenk et al.
patent: 5629055 (1997-05-01), Revol et al.
patent: 5686979 (1997-11-01), Weber et al.
patent: 5699188 (1997-12-01), Gilbert et al.
patent: 5721603 (1998-02-01), De Van et al.
patent: 5744534 (1998-04-01), Ishiharada et al.
patent: 5751388 (1998-05-01), Larson
patent: 5767935 (1998-06-01), Ueda et al.
patent: 5770306 (1998-06-01), Suzuki et al.
patent: 5783120 (1998-07-01), Ouderkirk et al.
patent: 5783283 (1998-07-01), Klein et al.
patent: 5793456 (1998-08-01), Broer et al.
patent: 5808794 (1998-09-01), Weber et al.
patent: 5825542 (1998-10-01), Cobb, Jr. et al.
patent: 5825543 (1998-10-01), Ouderkirk et al.
patent: 5882774 (1999-03-01), Jonza et al.
patent: 5940149 (1999-08-01), Vanderwerf
patent: 5962114 (1999-10-01), Jonza et al.
patent: 5965247 (1999-10-01), Jonza et al.
patent: 488 544 (1991-11-01), None
patent: 719 742 (1996-07-01), None
patent: WO 95/27919 (1995-04-01), None
patent: WO 95/17303 (1995-06-01), None
patent: WO 95/17691 (1995-06-01), None
patent: WO 95/17692 (1995-06-01), None
patent: WO 95/17699 (1995-06-01), None
patent: WO 96/19347 (1996-06-01), None
patent: WO 97/01440 (1997-01-01), None
patent: WO 97/01774 (1997-01-01), None
patent: WO 97/01778 (1997-01-01), None
patent: WO 97/32226 (1997-09-01), None
Schrenk et al., Nanolayer polymeric optical films, Tappi Journal, pp. 169-174, Jun. 1992.
Allen Richard C.
Condo Peter D.
Merrill William W.
Nevitt Timothy J.
Tabar Ronald J.
3M Innovative Properties
Dixon Merrick
Miller William D.
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