Stock material or miscellaneous articles – Structurally defined web or sheet – Including sheet or component perpendicular to plane of web...
Patent
1991-12-20
1993-10-19
Ryan, Patrick J.
Stock material or miscellaneous articles
Structurally defined web or sheet
Including sheet or component perpendicular to plane of web...
428163, 428167, 428168, 428170, 428212, 428218, 430 12, 430 23, B32B 300
Patent
active
052543889
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
U.S. Pat. No. Re. 27,617 (Olsen) teaches a process of making a louvered light control film by skiving a billet of altercating layers of plastic having relatively lower and relatively higher optical densities. Upon skiving the billet, the pigmented layers serve as louver elements, which, as illustrated in the patent, may extend orthogonally to the resulting louvered plastic film. U.S. Pat. No. 3,707,416 (Stevens) teaches a process whereby the louver elements may be canted with respect to the surface of the louvered plastic film to provide a film which transmits light in a direction other than perpendicular to the surface of the film. U.S. Pat. No. 3,919,559 (Stevens) teaches a process for attaining a gradual change in the angle of cant of successive louver elements.
Among the uses for such louvered plastic films are lenses and goggles as shown in U.S. Pat. No. 3,791,722 (Ahlberg et al.), to be worn where high levels of illumination or glare are encountered. The film may also be used for transparent covering for a backlighted instrument panel, such as the instrument panel of an automobile, to minimize reflections from the windshield. A louvered plastic film may also be used to give a black and white photographic negative the appearance of a positive made from the negative as taught in U.S. Pat. No. 3,653,138 (Cooper).
U.S. Pat. No. 3,922,440 (Wegwerth et al.) points out that because louvered plastic films to are thin sheet materials: (1) they are not by themselves capable of structurally withstanding extreme stresses and (2) they are subject to distortion from physical stress and temperatures" (col. 1, lines 19-22). Furthermore, the skiving by which the louvered plastic films are produced results in irregular surfaces which seriously limits the optical quality of the film. Typically such films are, for practical purposes, translucent rather than transparent. Accordingly, as in Example 1 of that patent, the louvered plastic film usually is laminated under pressure between two clear plastic films of a material such as cellulose acetate butyrate, the material usually used in making louvered plastic films. Typically, the louvered plastic film is skived from the billet to a thickness between 0.1 and 0.4 mm and each of the outer plastic films has a thickness of between 0.1 and 0.3 mm. The ratio of the thickness of the skived film to the width of the clear regions will control the permitted view angle, with a greater ratio providing a narrower angle. Wegwerth's process of laminating louvered plastic films between two clear films requires an expensive press which is also expensive to operate. This is in part from the need to distribute heat uniformly and in part from the need to apply pressure with precision. Because the resulting laminates can not be larger than the platens of the press in which they are laminated, the press must be sufficiently large to produce the required size thus increasing the expense of the press.
U.S. Pat. Nos. 4,764,410 (Grzywinski) and 4,766,023 (Lu) teach alterative to the Wegwerth method. These alternative methods include the steps of (1) coating the skived louvered plastic film with a solventless monomer composition which polymerizes to an adhesive state or a hard state, respectively, upon exposure to radiation, (2) overlaying the monomer composition with a plastic film, and (3) exposing the coating to radiation to polymerize the composition. After polymerization the plastic liner which was placed over the monomer composition may be left in place to serve as protection for the louvered plastic film, or may be removed, leaving the polymerized composition exposed.
Such films are used for various purposes. One common use is to prevent light from automobile control panels from reaching the windshield and causing distracting and dangerous reflections at night. Another use is to cover the screen of a CRT or other display to prevent persons other than the operator from reading data displayed thereon.
A problem that is common to all of the louvered films described
REFERENCES:
patent: Re27617 (1973-04-01), Olsen
patent: 3653138 (1972-04-01), Cooper
patent: 3707416 (1972-12-01), Stevens
patent: 3791722 (1974-02-01), Ahlberg et al.
patent: 3919559 (1975-11-01), Stevens
patent: 3922440 (1975-11-01), Wegwerth et al.
patent: 4342821 (1982-08-01), Galves et al.
patent: 4764410 (1988-08-01), Grzywinski
patent: 4766023 (1988-08-01), Lu
patent: 4788094 (1988-11-01), Morita et al.
patent: 4815821 (1989-03-01), Nonogaki et al.
Melby Jeffrey J.
Theirl Scott G.
Bahta Abraham
Buckingham Stephen W.
Griswold Gary L.
Kirn Walter N.
Minnesota Mining and Manufacturing Company
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