Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Layered – stratified traversely of length – or multiphase...
Reexamination Certificate
1999-02-26
2001-09-18
Silbaugh, Jan H. (Department: 1738)
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Layered, stratified traversely of length, or multiphase...
C264S171230
Reexamination Certificate
active
06290887
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to flame-retarding and, in particular, to compositions, products and methods that utilize superabsorbent polymers for flame-retarding.
2. Description of the Related Art
Superabsorbent materials generally are known as materials which can absorb up to about one thousand (1000) times their weight in distilled water. Superabsorbent materials, such as superabsorbent polymers (SAPs), for instance, are utilized in numerous applications. SAPs are commonly used in incontinent products, such as diapers, and other hygiene products, primarily due to their aforementioned water-absorption characteristics. SAPs also possess certain water-blocking characteristics which are utilized in numerous other applications, such as by incorporating the SAPs into telecommunications and power cables, as described in U.S. Pat. No. 4,867,526, issued to Arroyo, for example. In these applications, the SAPs typically are incorporated below the outer jacket of the cable, such as in a water-blocking tape, for instance. Upon contact with water, the SAPs absorb the water and swell, thereby preventing migration of the water through the cable. Additionally, the swelled SAPs form a physical barrier which prevents more water from entering the cable.
In many applications, a combination of water-blocking and flame-retarding is desired. Heretofore, a prior art solution to attain the characteristics of water-blocking and flame-retarding has been to add flame-retardants to SAPs. However, this oftentimes results in a SAP composition which has reduced water-blocking characteristics as compared to the SAPs without the flame-retardants. Primarily, this is due to the chemical properties of the prior art flame-retardants which, typically, are salts or ionic compounds that are known to reduce the swelling of water-blocking materials. Generally, as more prior art flame-retardants are added to SAPs in an effort to improve their flame-retarding characteristics, the greater the water-blocking capacity of the SAPs is reduced. Frequently, the extent of reduction in water-blocking capacity of SAPs due to incorporation of flame-retardants can render the SAPs incapable of preventing water penetration.
Therefore, there is a need for improved compositions, products and methods which address these and other shortcomings of the prior art.
BRIEF SUMMARY OF THE INVENTION
Certain objects, advantages and novel features of the invention will be set forth in part in the description that follows and in part will become apparent to those skilled in the art upon examination of the following or may be learned with the practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
The present invention generally is directed to compositions, products and methods that utilize superabsorbent polymers for flame-retarding. A preferred method includes improving flame-retarding characteristics in products by adding SAPs to the product. Prior to the step of adding the SAPs, the product exhibits a first limiting oxygen index and after the step of adding the SAPs, the product exhibits a second limiting oxygen index, with the second limiting oxygen index being higher than the first limiting oxygen index. Preferably, the SAPs include polyacrylates, polyacrylamides, polyvinylalcohols and combinations thereof, including copolymers.
In accordance with another aspect of the present invention, the SAPs are pre-loaded with moisture, thereby potentially further increasing the flame-retarding characteristics of the product. Depending on the particular application, the SAPs can incorporate a moisture content of higher than approximately 0 percent, by weight.
In accordance with another aspect of the present invention, SAPs are added to a composition, such as a plastic, thereby improving the flame-retarding characteristics of the composition. In a preferred embodiment, SAPs-enriched plastic is formed as an outer jacket of a cable. Preferably, such a cable incorporates a transmission medium and an outer jacket surrounding the transmission medium, with the outer jacket being formed by an extrusion technique.
In accordance with still another aspect of the present invention, a preferred method for providing water-blocking and non-halogen flame-retarding in a product includes adding moisture to a superabsorbent polymer so that the limiting oxygen index of the superabsorbent polymer is increased. Products with improved flame-retarding characteristics can then be formed from the superabsorbent polymer.
The numerous features and advantages of the present invention will be more readily apparent from the following detailed description read in conjunction with the accompanying drawings.
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C. John Arroyo, Jim J. Sheu, and W.J. Paucke, The Use of Superabsorbent Materials in Optical Fiber Cable Design, 1991.
Fredric L. Buchholz and Nicholas A. Peppas, Superabsorbent Polymers, Science and Technology, 1993.
Fredric L. Buchholz and Andrew T. Graham, Modern Superabsorbent Polymer Technology, 1998.
Lisa Brannon-Peppas and Ronald S. Harland, Absorbent Polymer Technology, Studies in Polymer Science 8, 1990.
Meeks Jennifer R.
Sheu Jim J.
Eashoo Mark
Lucent Technologies - Inc.
Silbaugh Jan H.
Thomas Kayden Horstemeyer & Risley LLP
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