Patent Application
20220084720
The present invention relates to a flame retardant for a jacket of a cable. More particularly, the present invention provides microencapsulated ammonium octamolybdate (AOM) in a jacket of a communications cable, so that the cable may show an improved performance in damp conditions.
Indoor plenum cables typically have a polymer jacket, such as a jacket including polyvinyl chloride (PVC) or fluorinated ethylene propylene (FEP) materials. Flame retardants are added to the jacket material so that smoke and flame are suppressed should a fire exist adjacent to the plenum cable. It is important to have a sufficient amount of flame retardant within the jacket material, as plenum cables often extend between floors of a multistory building and between rooms on a common floor, e.g., through HVAC ducts, electrical conduits, or simply inside walls and above drop tile ceilings. If a flame retardant is not added to the jacket material, the cable jacket may become a highly flammable substance during a fire and quickly allow a fire to spread between floors of a multistory building and/or between rooms on a common floor.
Plenum cables are designed as “indoor” cables, as such the cables do not typically have the robust qualities of “outdoor” rated cables. The jacket materials of an outdoor rated cable may include additives or surface treatments to resist exposure to the sun, e.g., ultraviolet (UV) light resistance, and an ability to resist direct contact with water, e.g., damp, high moisture situations. Outdoor cables also do not need to be as rigorous when it comes to smoke and flame retardants, since the smoke may dissipate to the outdoor environment. As such, a typical fire retardant additive for an outdoor jacket need not be as effective and/or costly as AOM, and is typically a much cheaper additive like red phosphorus, talc or clay.
The Applicant has appreciated certain drawbacks with the AOM fire retardant. AOM is considered the superior flame retardant for indoor plenum cables. However, under certain unusual circumstances AOM fails to perform well as a flame retardant.
As previously mentioned “indoor” plenum cables must have more smoke suppression abilities than “outdoor” cables. Also, indoor plenum cables are not designed for water exposure. Under some unusual circumstance, indoor plenum cable can be exposed to direct contact with water, or at least high humidity environments. Take for example a situation where a building's roof or fresh water piping or waste water piping has a leak. The leaking water sometimes comes into contact with a pathway of the indoor plenum cable.
If the leaking water enters the duct system, electrical conduit, wall or ceiling containing the plenum cable, an extended length of the plenum cable may be exposed to the water for an extended period of time. Sometimes, leaking water can even follow along the plenum cable for a distance before reaching a drip point. Also, in the case of an imbalance within an HVAC system, condensation can occur and travel along the ducts, and/or leak from the ducts into an electrical conduit, wall or ceiling. Also, high humidity rooms, such as swimming pool rooms, bathrooms, shower rooms, kitchens, etc., can produce excessive amounts of moisture, which may condensate into an area or along the outside walls of a water pipe and drip into ducts, conduits, walls or ceilings and contact the plenum cables.
The Applicant has discovered that the AOM fire retardant additive, when exposed to water and high humidity, will leach out of the cable jacket material. The AOM will follow along with the flow of water, e.g., within a conduit, along a duct, or along the cable jacket to the drip point. At the drip point, the AOM will deposit. Once, the moisture event dries up, the AOM will take the form of “salt-like” powdery material. For example, if the water flow passes along many feet of conduit into an electrical box, the AOM material may deposit a sizeable amount of powder at the bottom of the electrical box, e.g., up to one pound of the salt-like material.
The Applicant has appreciated two significant drawbacks to the unusual situations wherein the plenum cable jacket is exposed to water, as outlined above. First, some of the AOM within the plenum cable jacket is leaching out of the cable jacket. Hence, the flame and smoke retardant ability of the cable's jacket material is being reduced over time as the cable is exposed to water. As such, a plenum cable, which has been exposed repeatedly or long term to water or moisture may no longer have the needed flame and smoke resistance.
Second, the powdery substance 105, which is primarily leached out AOM, potentially chemically modified by the heat of the extrusion process when the jacket was applied to the cable, and potentially chemically combined or changed by the other elements forming the jacket material as well as the liquid that caused the leaching process, could be problematic to humans and the building's equipment. Construction workers often need to access the ductwork, conduits, ceiling spaces and electrical boxes for repairs and upgrades, and it would be better for the workers to not be exposed to the powdery substance 105.
In the case of ductwork, the powdery substance 105 could even enter the HVAC system. Also in the case of the powdery substance 105 deposited within a cabinet 100, the cabinet 100 may also house sensitive electronic equipment, like hard drives, equipment cooling fans 106, and optical connections via lasers and detectors, all or which could be adversely affected by powdery substance 105 within or adjacent to the cabinet 100.
The Applicant has invented adding microencapsulated AOM to the cable jacket to lessen or eliminate the potential drawbacks noted above. The cable jacket will still have the superior protection of the AOM fire retardant. However, the microencapsulated AOM fire retardant will no longer leach out of the cable jacket when the cable jacket is exposed to water.
Further, microencapsulating the AOM within the outer cable jacket may allow the plenum rated cable to be ran into an outdoor environment, especially if a UV inhibitor additive is added to the jacket material. Although the plenum rated cable is usually more expensive than the outdoor cable there are instances, where running the plenum cable outdoors for a short distance can be more economical. For example, if the run length is only several dozen feet, it would probably be more cost efficient to continue the indoor plenum cable to an outdoor unit, as opposed to terminating the indoor plenum cable to a junction box on the side of the building and then running several dozen feet of outdoor rated cable from the junction box to the outdoor unit. In other words, the cost and time associated with the junction box on the side of the building may exceed the added cost of the more expensive plenum cable.
These and other objects are accomplished by a communications cable including a communications carrying medium with a jacket surrounding the communications carrying medium, where the jacket is formed of a polymer having a microencapsulated ammonium octamolybdate (AOM) additive therein.
Moreover, these and other objects are accomplished by a communications cable including a communications carrying medium including a first insulated conductor and a second insulated conductor, wherein the first insulated conductor is twisted with the second insulated conductor to form a first twisted pair. An inner jacket surrounds the first twisted pair, and an outer jacket surrounds the inner jacket. The outer jacket is formed of a polymer having a microencapsulated AOM additive therein.
Further, these and other objects are accomplished by a method of making a communications cable. The method includes feeding a communications carrying medium from a reel. Then, extruding an outer jacket around the communications carrying medium, where the outer jacket is formed of a polymer having a microencapsulated AOM additive therein.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limits of the present invention, and wherein:
The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Broken lines illustrate optional features or operations unless specified otherwise.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.
As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.”
It will be understood that when an element is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature.
Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper”, “lateral”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly.
A separator 3 within the jacket 11 resides between and separates the first and fourth twisted pairs A and C from the second and third twisted pairs B and D. In
The first twisted pair A includes a first insulated conductor 13 and a second insulated conductor 15. The first insulated conductor 13 is twisted with the second insulated conductor 15, in a helical fashion, to form the first twisted pair A. The second twisted pair B includes a third insulated conductor 17 and a fourth insulated conductor 19. The third insulated conductor 17 is twisted with the fourth insulated conductor 19, in a helical fashion, to form the second twisted pair B. The third twisted pair C includes a fifth insulated conductor 21 and a sixth insulated conductor 23. The fifth insulated conductor 21 is twisted with the sixth insulated conductor 23, in a helical fashion, to form the third twisted pair C. The fourth twisted pair D includes a seventh insulated conductor 25 and an eighth insulated conductor 27. The seventh insulated conductor 25 is twisted with the eighth insulated conductor 27, in a helical fashion, to form the fourth twisted pair D.
The first through fourth twisted pairs A, B, C and D may be surrounded by a shielding layer 7 which overlaps itself at reference numeral 9. Although a shielded twisted pair cable is shown, the benefits of the present invention also extend to unshielded twisted pair cables, and dual jacketed twisted pair cables, as will be discussed hereinafter. The primary feature is to produce a plenum rated cable, capable of meeting the standards set by the National Fire Protection Association 262: Standard Method of Test for Flame Travel and Smoke of Wires and Cables for Use in Air-Handling Spaces, and/or the flame test specified by Underwriters Laboratories Inc. UL-910, and/or the Canadian Standards Associate (CSA) FT6.
The first twist length w of the first twisted pair A is preferably set to a short length, such as between approximately 0.22 inches and approximately 0.38 inches. The second twist length x of the second twisted pair B is different from the first twist length w and is between approximately 0.22 inches and approximately 0.38 inches. For example, the first twist length w may be set to approximately 0.26 inches and the second twist length x may be set to approximately 0.33 inches.
The first twist length w may purposefully modulate from a first average value, such as 0.26 inches. For example, the first twist length w could purposefully vary between 0.24 and 0.28 inches along the length of the cable. Likewise, the second twist length x could purposefully modulate from a second average value, such as 0.33 inches. For example, the second twist length x could purposefully vary between 0.31 and 0.35 inches along the length of the cable.
The third twisted pair C would have a third twist length y and the fourth twisted pair D would have a fourth twist length of z. In one embodiment, the third twist length y is different from the first, second and fourth twist lengths w, x and z, while the fourth twist length z is different from the first, second and third twist lengths w, x and y. Of course, the third and fourth twisted pairs C and D could employ a similar twist length modulation, as described in conjunction with the first and second twisted pairs A and B.
The first through fourth twisted pairs A, B, C and D may be stranded together in the direction 5 (see the arrow in
The strand length of the core strand is about five inches or less, more preferably about three inches or less. In a more preferred embodiment, the core strand length is purposefully varied, or modulates, from an average strand length along a length of the cable 1. Core strand modulation can assist in the reduction of alien crosstalk. For example, the core strand length could modulate between two inches and four inches along the length of the cable 1, with an average value of three inches. More details concerning modulation of the twisted pairs A, B, C and D and the core strand can be found in the Assignee's prior U.S. Pat. No. 6,875,928, titled “Localized Area Network Cabling Arrangement with Randomized Variation,” which is herein incorporated by reference.
Within the polymer 31 is microencapsulated AOM, graphically represented by a particle or particles of AOM 33 surrounded by an encapsulation shell 35, which may take the form of a coating. The encapsulation shell 35 is impervious to water. Thus, the encapsulation shell 35 will not allow the AOM on the outer surface of the jacket 11 to contact water, go into a solution form, and leach out from the polymer 31 at the outer surface of the jacket 11.
The encapsulation shell 35 is designed to remain stable at temperatures less than 450 degrees Fahrenheit, such as about 400 degrees Fahrenheit or less. In other words, the extrusion of the jacket 11 onto the cable core during the manufacturing process with not damage the encapsulation shell 35, such that the encapsulation shell 35 remains intact and surrounding the particle or particles of AOM 33. However, the encapsulation shell 35 will deteriorate and release the encapsulated particle or particles of AOM 33 at temperatures above 500 degrees Fahrenheit, such as above 600 degrees Fahrenheit. Such temperatures are indicative of a fire situation. Therefore, the AOM 33 will come into play in suppressing flame and/or smoke in the event of a fire.
Other additives 37 may also be present within the polymer 31. The other additives 37 may be microencapsulated or not microencapsulated. The other additives 37 may include additional fire retardants, like calcium carbonate, silica, talc, mica, and zinc borate (sold under the trademark FIRE BRAKE). The other additives 37 may also include an ultraviolet (UV) light resistance additive, additives to enhance the flexibility of the jacket 11, and/or additives that introduce a bitter taste or smell to the cable jacket 11 to deter rodents.
The plus-shaped separator 63 separates the first twisted pair A from the second, third and fourth twisted pairs B, C and D, separates the second twisted pair B from the third and fourth twisted pairs C and D, and also separates the third twisted pair C from the fourth twisted pair D. The plus-shaped separator 63 may be formed of any solid or foamed material common to the cabling art, such as a polyolefin or fluoropolymer, like fluorinated ethylene propylene (FEP) or polyvinylchloride (PVC). Also, the core may have a core twist in the direction indicated by arrow 5.
Unlike the embodiment of
The shielding layer 7 may take the form of a laminated foil, e.g., aluminum on MYLAR®. The shielding layer 7 may take the form of a braided shielding material. Also, the shielding layer 7 may include both types of shielding materials. A grounding or drain wire 67 may optionally be placed adjacent to the shielding layer 7, e.g., inside the shielding layer 7.
The shielding layer 7 is surrounded by an outer jacket 11. The outer jacket 11 may be constructed the same as the outer jacket 11 of
The inner jacket 65 may also be formed of the material depicted in
The extruding operation S103 may include melting S105 pellets formed of the polymer with the microencapsulated AOM additive 33 already within the pellets to form a compound. Alternative and as shown in
In the case of the dual jacket twisted pair cable 61 of
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.
This application is a continuation of International Application No. PCT/US2020/031490, filed May 5, 2020, which claims the benefit of U.S. Provisional Application No. 62/854,423, filed May 30, 2019, both of which are herein incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62854423 | May 2019 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/US2020/031490 | May 2020 | US |
| Child | 17537421 | US |
