Stock material or miscellaneous articles – Structurally defined web or sheet – Including variation in thickness
Reexamination Certificate
2003-01-06
2004-12-21
Berman, Susan (Department: 1711)
Stock material or miscellaneous articles
Structurally defined web or sheet
Including variation in thickness
C428S167000, C359S580000, C359S584000, C359S459000, C522S173000, C522S175000, C522S182000, C522S183000
Reexamination Certificate
active
06833176
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to the replication of microstructure-bearing surfaces, and more particularly to a genus of resinous compositions capable of such replication.
Microstructure replication in resinous surfaces is of importance in such diverse technical fields as the fabrication of traffic signs, in which reflectivity is provided by cube-corner embossed sheeting; the production of Fresnel ophthalmic lens elements and flexible video disks; and the fabrication of “brightness enhancement” or “light management” films (hereinafter sometimes designated “LMF” for brevity) for liquid crystal displays. For replication purposes, it is necessary that the resin have optimum physical properties, including a glass transition temperature (Tg) high enough for shape retention during storage and use and viscoelastic properties facilitating shaping, typically by molding, and long-term shape retention which includes the microstructure aspects of the shaped articles. Suitable viscoelastic properties include moduli in the glassy and rubbery states within certain ranges, as well as suitable transition temperatures between those states.
Many suitable resinous compositions for the replication of microstructure are disclosed in the patent literature. A patent whose disclosure is generic to a large variety of such compositions is U.S. Pat. No. 4,576,850. The compositions described therein are characterized by “hard” and “soft” segments or moieties in combination with radiation-polymerizable moieties. Most often, all three of these types of segments are present in the same molecule. A key feature of the “hard” segments is the presence therein of cyclic (i.e., carbocyclic or heterocyclic) groups. Later-issued patents frequently make reference to U.S. Pat. No. 4,576,850 for its disclosure of suitable polymeric compositions and precursors therefor.
It is of interest, however, to develop additional resinous LMF materials not disclosed in the above-identified patent or other publications.
SUMMARY OF THE INVENTION
The present invention is based on the discovery of a genus of acrylic-based resinous materials having excellent properties for the fabrication of LMF's and other articles having microstructure.
The invention includes articles which are radiation curable to optical resinous articles having surfaces with a replicated microstructure comprising a plurality of utilitarian discontinuities having an optical purpose, said optical resinous articles having a glass transition temperature of at least 35° C. Also included are the cured optical resinous articles so prepared.
Said radiation curable articles are free from carbocyclic and heterocyclic polymerizable moieties and comprise:
(A) at least one monofunctional acrylic monomer selected from the group consisting of:
(1) at least one monomeric t-alkyl (meth)acrylate,
(2) at least one monomeric N-substituted or N,N-disubstituted (meth)acrylamide and
(3) at least one C
1-8
primary or secondary alkyl (meth)acrylate;
(B) at least one multifunctional (meth)acrylate or (meth)acrylamide monomer;
(C) optionally, at least one oligomeric multifunctional (meth)acrylate; and
(D) at least one photoinitiator.
REFERENCES:
patent: 4576850 (1986-03-01), Martens
patent: 5175030 (1992-12-01), Lu et al.
patent: 5183597 (1993-02-01), Lu
patent: 5626800 (1997-05-01), Williams et al.
patent: 5635278 (1997-06-01), Williams
patent: 5650215 (1997-07-01), Mazurek et al.
patent: 5716681 (1998-02-01), Williams
patent: 5900287 (1999-05-01), Williams
patent: 9850805 (1998-11-01), None
Chisholm Bret Ja
Coyle Dennis Joseph
Hay Grant
Molaison Chris Anthony
Olson Daniel Robert
Berman Susan
Caruso Andrew J.
General Electric Company
Patnode Patrick K.
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