Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Compositions to be polymerized by wave energy wherein said...
Reexamination Certificate
1998-09-30
2001-11-27
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Compositions to be polymerized by wave energy wherein said...
C522S096000, C522S113000, C522S114000, C522S182000, C522S077000, C522S127000, C428S425600, C428S423100, C428S378000
Reexamination Certificate
active
06323255
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to radiation-curable compositions, their uses and preparations, which upon cure exhibit reduced discoloration over time and/or high elongation. In particular, the color stable and/or high elongation compositions of the present invention comprise at least one transesterified and/or high-purity monomer. These compositions are adaptable for a variety of uses including, for example, coatings on fiber optics and/or coatings which form part of fiber optic cable assemblies such as: primary, colored or uncolored outer primary coatings as well as other coatings including inks and matrix materials.
BACKGROUND OF THE INVENTION
Radiation-curable compositions are extensively used in the optical fiber industry during the production of optical fibers and cables. Optical fibers are routinely coated with at least one radiation-curable composition typically immediately after the optical fiber is manufactured in a draw tower so as to preserve the pristine character of the optical fiber. Immediately after the coating is applied to the fiber, the coating can be rapidly cured by exposure to radiation (commonly ultraviolet light). Radiation-curable composition may also be used as matrix materials to bundle together individual coated optical fibers into ribbons, optical fiber cables, and similar assemblies.
For purposes of multi-channel transmission, optical fiber assemblies containing a plurality of coated optical fibers have been used. Optical fiber assemblies provide a modular design which simplifies the installation and maintenance of optical fibers by eliminating the need to handle individual optical fibers. Examples of optical fiber assemblies include ribbon assemblies and cables. A typical optical fiber assembly is made of a plurality of coated optical fibers which are bonded together in a matrix material. For example, the matrix material can encase the optical fibers, or the matrix material can edge-bond the optical fibers together.
Coated optical fibers for use in optical fiber assemblies are usually coated with an outer colored layer, called an ink coating, or alternatively a colorant is added to the outer primary coating to facilitate identification of the individual coated optical glass fibers. Such ink coatings and colored outer primary coatings are well known in the art. Thus, the matrix material which binds the coated optical fibers together contacts the outer ink layer if present, or the colored outer primary coating.
Because a variety of competing characteristics are desired in optical fiber coating systems, multiple layers of coatings are routinely employed in optical fiber production. These typically include a soft inner primary coating and a tougher outer primary coating which provides a more durable exterior for the optical fiber. The outer primary coating may be uncolored (i.e., colorless) or include color which offers an identifier when coated onto an optical fiber. Examples of radiation-curable primary coatings are disclosed in U.S. Pat. No. 5,336,563 to Coady et al. the entire disclosure of which is hereby incorporated by reference. Additional aspects of optical fiber coating technology are disclosed in U.S. Pat. Nos. 5,199,098 to Nolan et al.; 4,923,915 to Urruti et al.; 4,720,529 to Kimura et al.; and 4,474,830 to Taylor et al.
A common type of radiation-curable composition include those having urethane-containing oligomers. Although such compositions are widely used, they suffer from photo-induced discoloration (more specifically, yellowing). The industry increasingly demands coatings, which are colorless or at least substantially colorless and will remain virtually colorless over time. Coatings with color stability, or colorless stability, serve an important function because they suggest a lack of coating degradation over time. More importantly, coated optical fibers are typically color-coded, and yellowing in a given coating can change or mask the color of the coated optical fiber. This presents problems, inter alia, when, for example, a worker in the field needs to repair or work on the optical fiber cable and, due to a color change of the coating over time, is unable to identify the desired fiber. Accordingly, there is a need for radiation-curable compositions which may be adapted for use as an inner primary and/or outer primary fiber optic coating as well as an ink, matrix material and the like that virtually does not discolor over time. There is also a need for colored coatings (which include colorless coatings mixed with colorants) to have the same reduced color degradation qualities.
U.S. Pat. Nos. 5,498,751, 5,554,785 and 5,606,103 to Trapasso et al., the entire disclosures of each are herein incorporated by reference, disclose monomers synthesized by transesterification, for example, isodecylacrylate. These monomers have excellent purity which means these monomers have low to no impurities such as color bodies that attribute to the lower color of these monomers. However, there is no disclosure in these patents that such monomers could be useful in fiber optic coating compositions or that they provide any effect in reducing discoloration or color degradation in cured radiation-curable compositions. In addition, there is no discussion in these patents that such monomers could provide a substantial increase in the elongation capabilities of cured radiation-curable composition.
SUMMARY OF THE INVENTION
The present invention provides radiation-curable compositions, uses and preparation thereof, that after cure provide reduced discoloration, or reduced color degradation, and/or high elongation while maintaining other desirable qualities of radiation-cured compositions. These radiation-curable compositions comprise at least one radiation-curable oligomer and at least one transesterified and/or high-purity monomer diluent. These radiation-curable compositions can be adapted to serve a variety of purposes. For example, these composition can be formulated to serve as protective coatings for substrates manufactured from a wide variety of materials to include, for example, glass, plastic, ceramic, metal and wood. The compositions of the present invention are preferably designed for use as an optical fiber coating (including primary and, colored or uncolored, outer primary coatings as well as other coatings which include inks, matrix materials and the like) or related optical fiber protective materials. Such optical fiber coatings have their own set of unique performance requirements, which distinguish them from conventional applications.
REFERENCES:
patent: 5498751 (1996-03-01), Trapasso et al.
patent: 5554785 (1996-09-01), Trapasso et al.
patent: 5587453 (1996-12-01), Abe et al.
patent: 5606103 (1997-02-01), Trapasso et al.
patent: WO 96/11217 (1996-04-01), None
patent: WO 97/16469 (1997-05-01), None
patent: WO 98/37030 (1998-08-01), None
patent: WO 98/41483 (1998-09-01), None
patent: WO 98/39264 (1998-09-01), None
DSM N.V.
McClendon Sanza
Pillsbury & Winthrop LLP
Seidleck James J.
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