Abstract:
A convenient compact telephone cord with a special coil diameter and a much smaller relaxed retracted length reduces sagging, occupies less space, and is much more attractive than conventional saggy telephone cords. The user-friendly high performance telephone cord has a core of electrical conductors which are insulated by primary insulation and are encased within an insulating jacket to meet or exceed national and international telephone standards and requirements. In the preferred form, the primary insulation comprises polypropylene and the insulating jacket comprises polyurethane and most preferably a blend of polyurethane and ethylene vinyl acetate. Desirably, the telephone cord comprises a modular retractile telephone cord with at least one modular plug. The attractive space-saving telephone cord can be used with handsets, headsets, vehicle phones, modems, and computers.

Description:
RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. Application Ser. No. 09/135,372 filed Aug. 17, 1998 of Jeffrey M. Morris and Yong R. Chu for Modular Retractile Telephone Cords, presently assigned to Group Art Unit 2831. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention pertains to telephone cords and, more particularly, to modular telephone cords. 
     Telephone cords are usually wound and coiled on mandrels to form spirals. Desirably, spiral telephone cords can be extended when using the telephones to which they are connected, and can be returned to their original retracted position when the telephones are not in use. Telephone cords have many uses. 
     Telephone cords used to connect a handset to a base should have sufficient retractility to insure that they will return in a controlled gradual manner to their normal retracted position after having been extended and released. Coiled or spiral telephone cords, however, which also known as “spring cords” or “retractile cords” should not be so strongly retractile that they require excessive forces to extend the telephone cord. If the telephone cord is too unyielding, the telephone handset or device to which the telephone cord is connected may be removed on or pulled from its support. While excessive retractility should be avoided, a telephone cord should not be made so stretchable that its distended spirals fail to return to their retracted position after using the telephone. This is especially important in order to prevent unsightly, excessive sag of telephone cords which are used on wall-mounted telephones. Furthermore, it is desirable that the retracted length of the telephone cord be as short as possible so as to be unobtrusive and avoid taking up excessive space and being distractive. In order to avoid this situation, telephone cords that are connected to telephone handsets must extend easily, perform dependably, and be as short as possible in their retracted position. 
     Retractable telephone cords are often constructed of cordage of individually insulated, mandrelated flexible conductor comprising tinsel ribbons. Conventional telephone cords are also often covered with nylon, insulated with polyvinyl chloride (PVC), and jacketed with a PVC composition in a circular configuration. 
     Telephone cords which utilize modular plugs for terminating the cord conductors are known as “modular telephone cords” . Jacks adapted to receive the modular plugs are mounted in the telephone housing or base and in a wall terminal thereby permitting easy replacement of either the line or retractile cord by a customer or an installer. Modular telephone cords have become very popular with consumers and telephone serviceman because of their ease of use and interchangeability. 
     The popularity of modular telephone cords with its associated plug-terminated cordage inspired the development of telephone cordage having a smaller cross-section than that used in the past. Conventional telephone cordage design suitable for use with modular plugs typically have smaller conductors arranged in a parallel relationship, positioned in a single plane, and encapsulated with a flattened oval-shaped jacket. To reduce the size of the insulated conductor, the knitted nylon covering the tinsel conductors was often eliminated and replaced with a crystalline thermoplastic elastomer. 
     It has been found that if top coated cordage is formed into a spring cord configuration, it has excellent retractile properties. However, when top-coated cordage is formed on mandrels of automatic cord making apparatus, the finished cords are so strongly retractile that excessive forces are required to stretch and expand the telephone cord. This problem occurs not only because of the top coating but also because of the relatively small diameter of the convolutions of the cordage. The diameter which is about 0.64 cm has been increased by forming the convolutions on larger diameter mandrels to achieve a top-coated cord having a larger diameter such as for example on the order of 0.95 cm. Although such prior art cords are suitably extensible, they lack good retractility. This is particularly noticeable in prior telephone cords which are used on wall-mounted telephones and which are desired to have an extended length of 7.6 meters and a retracted length of about 1 meter. 
     It is, therefore, desirable to provide improved modular retractile telephone cords which overcome most, if not all, of the preceding problems. 
     SUMMARY OF THE INVENTION 
     An improved telephone cord is provided which is compact, reliable, and economical. Advantageously, the space-saving telephone cord reduces sagging, is less obtrusive, and occupies a smaller area than conventional bulky saggy telephone cords. The attractive space-saving telephone cord is easy-to-use, convenient and effective. Desirably, the user-friendly telephone cord complies with telephone standards and requirements in the United States, Europe, Japan, and other countries. The novel telephone cord also achieved unexpected surprisingly good results. 
     The inventive telephone cord can be used as: a telephone handset cord for use with telephone handsets, a telephone headset cord for use with telephone headsets, a telephone vehicle cord for use with car phones or vehicles phones, a data transmission or receiving cord such as a telephone computer cord for use with a microprocessor, computer or central processing unit (CPU), or a telephone modem cord for use with a modem. 
     The telephone cord preferably comprises a modular retractile (retractable) telephone cord with at least one modular telephone plug at one end. The other end of the telephone cord can be connected to another modular telephone plug, or a different plug, or hardwire or otherwise connected to a telephone line or other circuitry. The modular telephone plug snap fits into a socket, jack, receptacle or other complementary-shaped female connector, in a telephone handset, base unit, wall receptacle, headset, etc. 
     The retractile telephone cord has a core comprising 2 to 8 conductors, preferably 4 to 7 conductors. For data transmission or receiving telephone cords, it is preferred that the conductors are twisted. For voice transmission or receiving telephone cords, it is preferred that the conductors are substantially parallel. The conductor can comprise wires, strands, or a flexible tinsel ribbon. 
     The conductors can be electrically insulated, isolated and separated from each other by primary insulation. The primary insulation can comprise an insulating material such as: a crystalline thermoplastic elastomer, polyethylene, polyvinyl chloride (PVC), nylon (polyamide), neoprene (polychloroprene)(polymerized chloroprene), polyurethane, polyurethane diisocyanate, urethane, butadiene, polystyrene, natural rubber (natural polyisoprene), styrene butadiene, acrobonitrile-butadiene, butyl rubber, vulcanized Hevea, Buna S, polysulfone, silicone, polysiloxane, chlorosulfanated polyethylene, or preferably polypropylene. 
     The retractile telephone cord can have a unitary or composite outer protective jacket positioned about the primary insulation and core. The outer protective jacket provides secondary insulation and can comprise an elastomeric insulating material, such as: polytetrafluroethylene (PTFE)(Teflon), polyvinyl chloride, nylon, neoprene, butadiene, polystyrene, styrene butadiene, acrolonitrile-butadiene, butyl rubber, vulcanized Hevea, Buna S, polysylfone, silicone, natural rubber, polyethylene, polypropylene, chlorosulfanated polyethylene, polysiloxane, or preferably polyurethane, polyurethane diisocyanate, or urethane, and most preferably, a blend of polyurethane and ethylene vinyl acetate (EVA). If desired, at least part of the jacket can be coated with another elastomeric insulating material. 
     The retractile telephone cord has a coiled portion between the ends of the cord. The coiled portion can be wound or coiled into spirals or helixes. The coiled portion has coils which have a maximum outside coil diameter when the telephone cord is in a relaxed retracted position. The coiled portion can be uniform and even in which all the coils have the same uniform maximum outside coil diameter. The coiled portion can also be tapered in which at least some of the coils have a different maximum outside coil diameter. Advantageously, the maximum outside coil diameter of the compact telephone cord is greater than 0.5 inches (12.07 mm), preferably at least 0.75 inches (19.05 mm), and most preferably at least one inch (245 mm). As used in this application, the terms “maximum coil diameter” and “maximum outside coil diameter” mean the maximum transverse span or the maximum outside diameter of the particular coil, spiral, helix, or loop of the telephone cord when the telephone cord is relaxed, unpulled, unstretched or retracted. 
     The compact retractile telephone cord can have a nominal uncoiled total length of 6 feet (1.8288 m), 12 feet (3.6576 m), or 25 feet (7.26 m), but has a much smaller relaxed retracted length than conventional telephone cords. The telephone cord can be expanded to an extended length of 790 to 7240 mm, preferably at least 1880 mm. The compact telephone cord can have a normal relaxed retracted length or recovered length of 70 to 1470 mm, preferably 150 to 648 mm. In the illustrative embodiment, the telephone cord had a recovered length ranging from 70 to 1140 mm after being subjected to a load of 170 gm for 300 seconds. 
     A more detailed explanation of the invention is provided in the following description and appended claims taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a modular telephone cord for voice transmission and receiving with a uniform diameter coiled portion in accordance with principles of the present invention; 
     FIG. 2 is an enlarged cross-sectional view of the modular telephone cord of FIG. 1; 
     FIG. 3 is a front view of a modular telephone cord for voice transmission and receiving with a tapered coiled portion in accordance with principles of the present invention; 
     FIG. 4 is an enlarged cross-sectional view of a modular telephone cord for data transmission and receiving; 
     FIG. 5 is a fragmentary front view of the modular telephone cord of FIG. 4 without the modular plugs and illustrating the twisted conductors of the interior core; 
     FIG. 6 is a perspective view of a modular telephone cord connected to a telephone for positioning on a table; and 
     FIG. 7 is a perspective view of a modular telephone cord connected to a wall-mounted telephone. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Compact space-saving large diameter modular retractile (retractable) telephone cords  10 ,  32  and  50  (FIGS. 1,  3 , and  5 ) are provided with much smaller relaxed retracted lengths to reduce unsightly sagging and occupy much less space than previous conventional telephone cords. 
     The telephone cord  10  (FIGS. 1 and 6) can comprise a telephone handset cord for connecting a telephone handset to a telephone base unit. The telephone handset cord comprises a modular retractile telephone cord which provides a cordage assembly  12  with a spiral wound coiled portion  14  that extends between and is connected to a handset-facing end  16  and a base-facing end  18  of the telephone cord. The spiral wound coiled portion comprises a series, set, or array of coils  20  which provide loops. The coil preferably comprise spiral coils (spirals), and most preferably helical coils (helixes). 
     The modular telephone cord has at least one modular plug  22  (FIG. 1) connected to one of the ends of the telephone cord, and preferably has two plastic modular telephone plugs  22  and  24  connected to opposite ends of the telephone cord. The telephone handset cord has a handset-connecting modular plug  22  which is connected to the handset-facing end of the telephone cord and has a base-connecting modular plug  24  which is connected to the base-facing end of the telephone cord. The handset-connecting modular plug provides a telephone handset connector which snap fits and interlockingly engages, as well as can be detachably secured and removably connected to a complementary-shaped female socket or jack of a telephone handset. The base-connecting modular plug provides a base unit connector which snap fits and interlockingly engages, as well as can be detachably secured and removably connected to a complementary-shaped female socket or jack of a telephone base unit. 
     Each of the modular plugs has a wedging cantilevered connecting arm  26  or  27  (FIG. 1) which is connected to and normally biased outwardly at an angle of inclination away from the front nose  28  or  29  of the head  30  or  31  or body of the modular plug. The connecting arm extends generally towards the coiled portion of the telephone cord, but normally diverges away from the end of the cord to which the modular plug is connected. The connecting arm can be squeezed and pivoted toward and against the side of the head or body of the modular plug, when the modular plug is inserted or removed from a socket or jack of a handset, base unit, headset, wall receptacle, computer, modem, appliance, or other apparatus. When inserted into a complementary socket or jack, the connecting arm of the modular plug securely wedges against, snap fits, and lockably engages the adjoining wall portious of the socket or jack. 
     The modular retractile telephone cord is biased in a normally relaxed retracted position to a collapsed retracted length when the telephone cord is stored, awaiting use, unstretched, unpulled, relaxed, and retracted. The modular retractile telephone cord can be expanded to an elongated stretched extended position to an extended length when the telephone cord is pulled, stretched, and extended. The telephone handset cord is biased and urged in a normally relaxed position when the handset is cradled or seated on the base unit when the telephone is not in use and no voice signals or data pulses are being sent (transmitted) or received. The telephone handset cord is expanded to an elongated stretched extended position when the handset is moved away from the base unit when the telephone is in use and voice signals or data pulses are being transmitted or received. Preferably, the extended length is at least 5 times greater than the retracted length of the telephone cord. Desirably, the retracted length of the telephone cord is less than 15%, preferably less than 10%, of the extended length of the telephone cord. The telephone cords are preferably produced in nominal total uncoiled lengths of 6 feet (ft.) (1.8288 m), 12 ft. (3.6576 m) and 25 ft. (7.62 m). 
     The coils of the modular telephone cord have a greater maximum coil diameter and are positioned closer together when the telephone cord is in a relaxed retracted position. The coils have a maximum coil diameter of 0.5 inches (12.07 mm), preferably at least 0.75 inches (19.09 mm), and most preferably at least one inch, (25.55 mm), when the telephone cord is in a retracted position. In the telephone cord of FIG. 1, the coiled portion is uniform and comprise uniform coils, preferably spiral coils, and most preferably helical coils, having the same maximum coil diameter when the telephone cord is in the retracted position. Conversely, the coils have a smaller coil diameter and are positioned farther apart when the telephone cord is stretched or expanded to its maximum extended position. 
     The modular telephone cord  32  of FIGS. 3 and 7 is structurally and functionally similar to the modular telephone cord of FIG. 1, except that the coiled portion comprises a sloping bulging barrel-shaped tapered coiled portion  34  in which the coils  36  gradually taper, increase or decrease in size. At least some of the coils of the tapered coil portion have different maximum coil diameters when the telephone cord is in a retracted position. 
     The cordage assembly of the modular telephone cord can comprise a core  40  (FIG. 2) with 2 to 8 and preferably 4 to 7 electrical conductors  42 . For voice transmission and receiving, the conductors preferably comprise parallel flexible electrical conductors, most preferably flexible tinsel ribbon  44  comprising flexible tinsel wire strands. The tinsel ribbon can be made of phosphorous bronze or other suitable conductive material. 
     The modular telephone cord  50  of FIGS. 4 and 5 are structurally and functionally similar to the modular telephone cord of FIG. 1, except that the conductors of the core  51  are twisted to form twisted conductors  52  which provide a cable to transmit and receive data. In one preferred form, each of the conductors comprise 26-28 AWG (American Wire Gauge) wire and have a diameter ranging from 0.015 inches (0.38 mm) to 0.024 inches (0.61 mm). Preferably, the conductors have a tensile pull strength of at least 44.5 N. 
     The electrical conductors are electrically insulated, isolated, and physically separated from each other by primary insulation  54  (FIGS.  2  and  4 ). In the preferred form, the primary insulation comprises polypropylene, has an insulation resistance more than 150 Ω·km, and has a dielectric constant at 10 6  Hz of 2.20-2.28. The dielectric strength between conductors is such that there is no breakdown at 1000 VAC for one minute. Preferably, the primary insulation has a wall thickness greater than 0.004 inches (0.1016 mm). 
     The cordage assembly of the modular telephone cord has an outer protective jacket  56  or  58  (FIGS. 2 and 4) which provides a secondary insulation and an electrical insulation sheath that annularly surrounds, encloses and encases the primary insulation and core of conductors. In the preferred form, the outer protective jacket comprises urethane or most preferably polyurethane, with a dielectric constant at 10 6  Hz of 5-8. Desirably, the outer protective jacket comprises a blend of polyurethane and ethylene vinyl acetate (EVA), such as by weight: 80% polyurethane and 20% EVA, and preferably, 90% polyurethane and 10% EVA. The composite outer protective jacket can comprise by weight: 50%-99% polyurethane and 1%-50% EVA. Preferably, the outer protective jacket has a wall thickness greater than 0.1 inches (2.54 mm) and a tensile strength greater than 1200 psi (84,368,35 g/cm  2 ). If desired, part or all of the exterior surface of the outer protective jacket can be coated with an elastomeric insulating layer  60  (coating) (FIG.  2 ), such as a 0.005 cm layer of polyester or other plastic, to enhance protection, insulation, and retractility. The outer protective jacket  56  (FIG.  2 ), enclosing the parallel conductors preferably has a generally elliptical or oval exterior surface  62 , periphery and shape. The outer protective jacket  56  positioned about the parallel conductors can also have parallel elongated sides  64  and  66  and curved arcuate ends  68  and  70 . The outer protective jacket  58  (FIG. 4) enclosing and positioned about the twisted conductors can have a circular exterior surface  72 , periphery and shape. 
     The illustrated modular telephone cords can also be used as: telephone headset cords for use with telephone headsets, telephone vehicle cords for use with car phones or vehicle phones, data transmission or receiving cords such as telephone computer cords for use with microprocessors, central processing units (CPUs), and computers, or telephone modem cords for use with modems. 
     EXAMPLES 1-8 
     Retractile telephone cords of the type described above were formed with a maximum outside coil diameter of 0.75 inches (19.05 mm). The telephone cords had a uniform outside coil diameter as shown in FIG.  1 . The telephone cords were also constructed with an oval cross-sectional configuration with elongated flattened sides as shown in FIG.  2  and had an interior core comprising four flexible tinsel copper conductors. The conductors were insulated with a polypropylene primary insulation. 
     Telephone cords  1 - 3  had an outer protective jacket consisting essentially of polyurethane. Telephone cords  4 - 6  had an outer protective jacket consisting essentially of polyvinyl chloride (PVC). Telephone cords  7  and  8  had composite outer protective jacket consisting essentially of by weight: 90% polyurethane and 10% ethylene vinyl acetate (EVA). Telephone cords  1  and  4  had a total nominal uncoiled length of 6 feet (1.8288 mm). Telephone cords  2 ,  5  and  7  had a total nominal uncoiled length of 12 feet (3.6576 m). Telephone cords  3 ,  6  and  8  had a total nominal uncoiled length of 25 feet (7.26 m). 
     The telephone cords had a retracted length as shown in Table 1 as follows: 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 Retracted Length 
               
             
          
           
               
                   
                   
                   
                   
                 Re- 
               
               
                 Exam- 
                 Retractile 
                 Total Nominal 
                   
                 tracted 
               
               
                 ple 
                 Telephone 
                 Uncoiled Length 
                   
                 Length 
               
               
                 No. 
                 Cord 
                 (feet) 
                 Outer Protective Jacket 
                 (mm) 
               
               
                   
               
               
                 1 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                 150 
               
               
                 2 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 287 
               
               
                 3 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 848 
               
               
                 4 
                 4 
                  6 (1.8288 m) 
                 PVC 
                 197 
               
               
                 5 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 288 
               
               
                 6 
                 6 
                 25 (7.26 m) 
                 PVC 
                 880 
               
               
                 7 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + EVA 
                 305 
               
               
                 8 
                 8 
                 25 (7.26 m) 
                 Polyurethane + EVA 
                 660 
               
               
                   
               
             
          
         
       
     
     It is evident from Examples 1-8 that telephone cords with 100% polyurethane jackets had a smaller retracted length than telephone cords with PVC jackets. 
     EXAMPLES 9-16 
     The retractile telephone cords of Examples 1-8 were expanded and stretched to a maximum extended position as indicated in Table 2 below, without interfering with their ability to return to their normal unstretched retracted position. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 Extended Length 
               
             
          
           
               
                   
                   
                   
                   
                 Ex- 
               
               
                 Exam- 
                 Retractile 
                 Total Nominal 
                   
                 tended 
               
               
                 ple 
                 Telephone 
                 Uncoiled Length 
                   
                 Length 
               
               
                 No. 
                 Cord 
                 (feet) 
                 Outer Protective Jacket 
                 (mm) 
               
               
                   
               
               
                  9 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                 1660 
               
               
                 10 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 3420 
               
               
                 11 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 7240 
               
               
                 12 
                 4 
                  6 (1.8288 m) 
                 PVC 
                 1620 
               
               
                 13 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 3380 
               
               
                 14 
                 6 
                 25 (7.26 m) 
                 PVC 
                 7080 
               
               
                 15 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + EVA 
                 3404 
               
               
                 16 
                 8 
                 25 (7.26 m) 
                 Polyurethane + EVA 
                 7163 
               
               
                   
               
             
          
         
       
     
     It is evident from Examples 9-16 that telephone cords with 100% polyurethane jackets and with composite jackets of polyurethane and ethylene vinyl acetate (EVA) have a greater extended length than telephone cords with PVC jackets. 
     EXAMPLES 17-57 
     Retractile telephone cords were formed and constructed as described in Examples 1-8 and were hung vertically. The top ends of the telephone cords were secured and fixed in a stationary position. Weights were connected and added to the bottoms of the telephone cords to stretch, extend, and expand the telephone cords an additional length of 0.3 m, 1.0 m, 1.2 m, 1.5 m, 1.7 m, and 1.8 m as indicated in Table 3 below. The amount of weights (load) required to stretch, extend and expand the telephone cords to the additional lengths are also shown in Table 3 below. 
     
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 Additional Length and Load 
               
             
          
           
               
                   
                   
                 Total Nor- 
                   
                 Addi- 
                   
               
               
                 Exam- 
                 Tele- 
                 mal Uncoiled 
                   
                 tional 
               
               
                 ple 
                 phone 
                 Length 
                 Outer 
                 Length 
                 Load 
               
               
                 No. 
                 Cord 
                 (Feet) 
                 Protective Jacket 
                 (m) 
                 (gm) 
               
               
                   
               
               
                 17 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                 0.3 
                  72 
               
               
                 18 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                 1.0 
                 180 
               
               
                 19 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                 1.2 
                 270 
               
               
                 20 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 0.3 
                  80 
               
               
                 21 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 1.0 
                 115 
               
               
                 22 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 1.2 
                 140 
               
               
                 23 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 1.5 
                 150 
               
               
                 24 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 1.7 
                 175 
               
               
                 25 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 1.8 
                 180 
               
               
                 26 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 0.3 
                 110 
               
               
                 27 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 1.0 
                 150 
               
               
                 28 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 1.2 
                 152 
               
               
                 29 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 1.5 
                 155 
               
               
                 30 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 1.7 
                 160 
               
               
                 31 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 1.8 
                 165 
               
               
                 32 
                 4 
                  6 (1.8288 m) 
                 PVC 
                 0.3 
                  70 
               
               
                 33 
                 4 
                  6 (1.8288 m) 
                 PVC 
                 1.0 
                 160 
               
               
                 34 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 0.3 
                  80 
               
               
                 35 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 1.0 
                 110 
               
               
                 36 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 1.2 
                 140 
               
               
                 37 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 1.5 
                 150 
               
               
                 38 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 1.7 
                 160 
               
               
                 39 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 1.8 
                 165 
               
               
                 40 
                 6 
                 25 (7.26 m) 
                 PVC 
                 0.3 
                 110 
               
               
                 41 
                 6 
                 25 (7.26 m) 
                 PVC 
                 1.0 
                 145 
               
               
                 42 
                 6 
                 25 (7.26 m) 
                 PVC 
                 1.2 
                 150 
               
               
                 43 
                 6 
                 25 (7.26 m) 
                 PVC 
                 1.6 
                 155 
               
               
                 44 
                 6 
                 25 (7.26 m) 
                 PVC 
                 1.7 
                 160 
               
               
                 45 
                 6 
                 25 (7.26 m) 
                 PVC 
                 1.8 
                 165 
               
               
                 46 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + 
                 0.3 
                  80 
               
               
                   
                   
                   
                 EVA 
               
               
                 47 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + 
                 1.0 
                 130 
               
               
                   
                   
                   
                 EVA 
               
               
                 48 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + 
                 1.2 
                 140 
               
               
                   
                   
                   
                 EVA 
               
               
                 49 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + 
                 1.5 
                 150 
               
               
                   
                   
                   
                 EVA 
               
               
                 50 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + 
                 1.7 
                 180 
               
               
                   
                   
                   
                 EVA 
               
               
                 51 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + 
                 1.8 
                 185 
               
               
                   
                   
                   
                 EVA 
               
               
                 52 
                 8 
                 25 (7.26 m) 
                 Polyurethane + 
                 0.3 
                 110 
               
               
                   
                   
                   
                 EVA 
               
               
                 53 
                 8 
                 25 (7.26 m) 
                 Polyurethane + 
                 1.0 
                 180 
               
               
                   
                   
                   
                 EVA 
               
               
                 54 
                 8 
                 25 (7.26 m) 
                 Polyurethane + 
                 1.2 
                 150 
               
               
                   
                   
                   
                 EVA 
               
               
                 55 
                 8 
                 25 (7.26 m) 
                 Polyurethane + 
                 1.5 
                 155 
               
               
                   
                   
                   
                 EVA 
               
               
                 56 
                 8 
                 25 (7.26 m) 
                 Polyurethane + 
                 1.7 
                 160 
               
               
                   
                   
                   
                 EVA 
               
               
                 57 
                 8 
                 25 (7.26 m) 
                 Polyurethane + 
                 1.8 
                 165 
               
               
                   
                   
                   
                 EVA 
               
               
                   
               
             
          
         
       
     
     EXAMPLES 58-65 
     Retractile telephone cords were formed and constructed as described in Example 1-8. The top ends of the telephone cords were secured and fixed in a stationary position. Loads (weights) of 170 gm were connected and added to the bottom of the telephone cords for 60 seconds to stretch, extend, and expand the telephone cords to the loaded lengths indicated in Table 4 below: 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 Extension Tests 
               
             
          
           
               
                 Exam- 
                 Retractile 
                 Total Nominal 
                   
                   
               
               
                 ple 
                 Telephone 
                 Uncoiled Length 
                   
                 Loaded 
               
               
                 No. 
                 Cords 
                 (Feet) 
                 Outer Protective Jacket 
                 Length 
               
               
                   
               
               
                 58 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                  790 
               
               
                 59 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 2270 
               
               
                 60 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 3390 
               
               
                 61 
                 4 
                  6 (1.8288 m) 
                 PVC 
                 1005 
               
               
                 62 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 2340 
               
               
                 63 
                 6 
                 25 (7.26 m) 
                 PVC 
                 3890 
               
               
                 64 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + EVA 
                 1651 
               
               
                 65 
                 8 
                 25 (7.26 m) 
                 Polyurethane + EVA 
                 4089 
               
               
                   
               
             
          
         
       
     
     It appears from Examples 58-65 that the loaded lengths of telephone cords with 100% polyurethane jackets and with composite jackets of polyurethane and ethylene vinyl acetate (EVA) are smaller than the loaded lengths of telephone cords with PVC jackets. 
     EXAMPLES 66-73 
     Retractile telephone cords were formed and constructed as described in Examples 1-8. The top ends of the telephone cords were secured and fixed in a stationary position. Loads (weights) of 170 gm were hung from the bottoms of the telephone cords for 300 seconds. The loads (weights) were than removed and the bottom ends of the telephone cords moved upwardly as the telephone cords retracted to the recovered lengths indicated in Table 5 below. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 Recovery Tests 
               
             
          
           
               
                   
                   
                   
                   
                 Re- 
               
               
                 Exam- 
                 Retractile 
                 Total Nominal 
                   
                 covered 
               
               
                 ple 
                 Telephone 
                 Uncoiled Length 
                   
                 Length 
               
               
                 No. 
                 Cord 
                 (Feet) 
                 Outer Protective Jacket 
                 (mm) 
               
               
                   
               
               
                 66 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                  70 
               
               
                 67 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 283 
               
               
                 68 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 1140  
               
               
                 69 
                 4 
                  6 (1.8288 m) 
                 PVC 
                 145 
               
               
                 70 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 460 
               
               
                 71 
                 6 
                 25 (7.26 m) 
                 PVC 
                 1470  
               
               
                 72 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + EVA 
                 305 
               
               
                 73 
                 8 
                 25 (7.26 m) 
                 Polyurethane + EVA 
                 660 
               
               
                   
               
             
          
         
       
     
     Examples 66-73 clearly indicate that the recovered lengths of telephone cords with 100% polyurethane jackets and with composite jackets of polyurethane and ethylene vinyl acetate (EVA) are smaller than telephone cords with PVC jackets. 
     EXAMPLES 74-81 
     Retractile telephone cords were formed and constructed as described in Examples 1-8. The top ends of the telephone cords were secured and fixed in a stationary position. The telephone cords were each stretch, expanded, and extended to an additional length of 1.2 meters (m) for 30 minutes by adding and connecting appropriate weights to the bottoms of the telephone cords. Afterwards, the loads (weights) were removed and the bottom ends of the telephone cords retracted upwardly. Five minutes after the load (weight) was released and removed, the recovered lengths of the telephone cords were measured. The recovered length of the telephone cords are indicated in Table 6 below. 
     
       
         
               
             
               
               
               
               
               
             
           
               
                 TABLE 6 
               
             
             
               
                   
               
               
                 Extension and Recovery 
               
             
          
           
               
                   
                   
                   
                   
                 Re- 
               
               
                 Exam- 
                 Retractile 
                 Total Nominal 
                   
                 covered 
               
               
                 ple 
                 Telephone 
                 Uncoiled Length 
                   
                 Length 
               
               
                 No. 
                 Cord 
                 (Feet) 
                 Outer Protective Jacket 
                 (mm) 
               
               
                   
               
               
                 74 
                 1 
                  6 (1.8288 m) 
                 Polyurethane 
                 137 
               
               
                 75 
                 2 
                 12 (3.6576 m) 
                 Polyurethane 
                 260 
               
               
                 76 
                 3 
                 25 (7.26 m) 
                 Polyurethane 
                 670 
               
               
                 77 
                 4 
                  6 (1.8288 m) 
                 PVC 
                 201 
               
               
                 78 
                 5 
                 12 (3.6576 m) 
                 PVC 
                 335 
               
               
                 79 
                 6 
                 25 (7.26 m) 
                 PVC 
                 910 
               
               
                 80 
                 7 
                 12 (3.6576 m) 
                 Polyurethane + EVA 
                 336 
               
               
                 81 
                 8 
                 25 (7.26 m) 
                 Polyurethane + EVA 
                 654 
               
               
                   
               
             
          
         
       
     
     As is evident from Examples 74-81, retractile telephone cords with 100% polyurethane jackets and with composite jackets of polyurethane and ethylene vinyl acetate (EVA) have a smaller recovered length than retractile telephone cords with PVC jackets. 
     EXAMPLES 82-91 
     Retractile telephone cords of similar lengths were formed and tested with a polyproylene primary insulation and an outer protective jacket comprising different density polyurethane elastomeric secondary insulation. The hardness, modulus, tensile strength, elongation at break, taper abrasion, and brittleness points of the retractile telephone cords are indicated in Table 7 below. 
     
       
         
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 7 
               
             
             
               
                   
               
               
                 Retractile Cords With Different Density 
               
               
                 Polyurethane Outer Protective Jackets 
               
             
          
           
               
                 Example 
                 No. 
                 82 
                 83 
                 84 
                 85 
                 86 
                 87 
                 88 
                 89 
                 90 
                 91 
               
               
                   
               
             
          
           
               
                 Hardness 
                 Shore 
                 80A 
                 85A 
                 90A 
                 95A 
                 98A 
                 80A 
                 85A 
                 90A 
                 95A 
                 98A 
               
               
                   
                 A/D 
               
               
                 100% 
                 kgf/cm 2   
                 60 
                 80 
                 100 
                 120 
                 150 
                 50 
                 70 
                 90 
                 110 
                 140 
               
               
                 Modulus 
               
               
                 Tensile 
                 kgf/cm 2   
                 350 
                 380 
                 400 
                 420 
                 440 
                 360 
                 380 
                 420 
                 430 
                 440 
               
               
                 Strength 
               
               
                 Elongation 
                 % 
                 640 
                 600 
                 550 
                 460 
                 450 
                 650 
                 600 
                 580 
                 520 
                 500 
               
               
                 at Break 
               
               
                 Taper 
                 mg 
                 30 
                 30 
                 30 
                 25 
                 25 
                 30 
                 30 
                 30 
                 25 
                 25 
               
               
                 Abrasion 
               
               
                 Brittleness 
                 ° C. 
                 &lt;−50 
                 &lt;−50 
                 &lt;−50 
                 &lt;−40 
                 &lt;−40 
                 &lt;−50 
                 &lt;−50 
                 &lt;−50 
                 &lt;−50 
                 &lt;−40 
               
               
                 Point 
               
               
                   
               
             
          
         
       
     
     Examples 82-91 indicate that the hardness, modulus, tensile strength, elongation at breaking point, taper abrasion, and brittleness point varied with the type of polyurethane used. Example 85 had the most preferred qualities in Table 7. 
     In some circumstances, it may be desirable that the primary insulation comprise: polyurethane, polyurethane-diisocyanate, urethane, polyethylene, polyvinyl chloride, polysulfone, polystyrene, neoprene, butadiene, styrene butadiene rubber, vulcanized Hevea, Buna S, butyl rubber, natural rubber (polyisoprene), acrylonitrile-butadiene, silicone, polysiloxane, chlorsulfanated polyethylene, nylon (polyamide), crystalline thermoplastic elastomer, or other plastic insulating material. 
     Furthermore, in some circumstances, it may be desirable that the outer protective jacket providing the secondary insulation, comprises: polytetrafluoroethylene (PTFE) (Teflon), polypropylene, , polyethylene, polyvinyl chloride, polysulfone, polystyrene, neoprene, butadiene, styrene butadiene rubber, vulcanized Hevea, Buna S, butyl rubber, natural rubber (polyisoprene), acrylonitrile-butadiene, silicone, polysiloxane, chlorsulfanated polyethylene, nylon (polyamide), or other plastic insulating material. 
     The dielectric constant, power factor, volume resistivity, surface resistivity, and dielectric strength of some of the preceding rubber and elastomeric insulators are shown in Table 8 below. 
     
       
         
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 8 
               
             
             
               
                   
               
               
                 Properties of Rubbers and Elastomeric Insulators 
               
             
          
           
               
                   
                   
                 Power 
                   
                   
                   
               
               
                   
                 Di-electric 
                 factor X 
                 Volume 
                 Surface 
                 Di-electric 
               
               
                   
                 constant, 
                 10 2 , 10 6   
                 resistivity, 
                 resistivity, 
                 strength, 
               
               
                 Material 
                 10 6  Hz 
                 Hz 
                 Ω · cm 
                 Ω 
                 V/mil 
               
               
                   
               
               
                 Natural 
                 2.7-5   
                 0.05-0.2  
                 10 15 -10 17   
                 10 14 -10 15   
                 450-600 
               
               
                 rubber 
               
               
                 Styrene- 
                 2.8-4.2 
                 0.5-3.5 
                 10 14 -10 16   
                 10 13 -10 14   
                 450-600 
               
               
                 butadiene 
               
               
                 rubber 
               
               
                 Acryloni- 
                  3.9-10.0 
                 3-5 
                 10 12 -10 15   
                 10 12 -10 15   
                 400-500 
               
               
                 trile-buta- 
               
               
                 diene rubber 
               
               
                 Butyl 
                 2.1-4.0 
                 0.3-8.0 
                 10 14 -10 16   
                 10 13 -10 14   
                 400-800 
               
               
                 rubber 
               
               
                 Chlorosulfo- 
                  5.0-11.0 
                 2.0-9.0 
                 10 13 -10 17   
                 10 14   
                 400-600 
               
               
                 nated poly- 
               
               
                 ethylene 
               
               
                 Polyurethane 
                 5.0-8.0 
                 3.0-6.0 
                 10 10 -10 11   
                   
                 450-500 
               
               
                   
               
             
          
         
       
     
     The dielectric constants at different frequencies for some of the preceding insulators are shown in Table 9 below. 
     
       
         
               
             
               
               
             
               
               
               
               
               
             
           
               
                 TABLE 9 
               
             
             
               
                   
               
               
                 Dielectric Constants of Insulators at Different Frequencies 
               
             
          
           
               
                   
                 Frequency (Hertz) 
               
             
          
           
               
                 Material 
                 ° C. 
                 1 × 10 3   
                 1 × 10 6   
                 1 × 10 8   
               
               
                   
               
               
                 Polyamide resins: 
                   
                   
                   
                   
               
               
                 Nylon 66 
                 25 
                 3.75 
                 3.33 
                 3.16 
               
               
                 Nylon 610 
                 25 
                 3.50 
                 3.14 
                 3.0  
               
               
                 Polyethylene 
                 −12  
                 2.37 
                 2.35 
                 2.33 
               
               
                   
                 23 
                 2.26 
                 2.26 
                 2.26 
               
               
                 Polyvinyl chloride 
                 25 
                 4.55 
                 3.3  
               
               
                 Polystyrene 
                   2.5 
                 2.54-2.56 
                 2.54-2.56 
                 2.55 
               
               
                   
                 80 
                 2.54 
                 2.54 
                 2.54 
               
               
                 Hevea, vulcanized 
                 27 
                 2.94 
                 2.74 
                 2.42 
               
               
                 Buna S 
                 20 
                 2.66 
                 2.56 
                 2.52 
               
               
                 Butyl rubber compound 
                 25 
                 2.42 
                 2.40 
                 2.39 
               
               
                 Neoprene 
                 24 
                 6.60 
                 6.26 
                 4.5  
               
               
                 Silicon rubber 
                 25 
                 3.12-3.30 
                 3.10-3.20 
                 3.06-3.18 
               
               
                   
               
             
          
         
       
     
     The dielectric constants and dissipation factors (loss) for some of the preceding insulators are shown in Table 10 below. 
     
       
         
               
             
               
               
               
             
           
               
                 TABLE 10 
               
             
             
               
                   
               
               
                 Dielectric Constants and Dissipation Factors of Insulators 
               
             
          
           
               
                   
                 Dielectric constant 
                 Dissipation 
               
               
                 Material 
                 At 10 6  Hz 
                 Factor at 10 6  Hz 
               
               
                   
               
               
                 PTFE, (Teflon) 
                 2.0 
                 0.0002-0.0003 
               
               
                 Nylon 6 and nylon 10 
                 3.5-3.6 
                 0.04 
               
               
                 Polypropylene 
                 2.20-2.28 
                 0.0002-0.002  
               
               
                 Silicones 
                 3.4-4.3 
                 0.001-0.004 
               
               
                   
               
             
          
         
       
     
     The arc resistance, dielectric constants, dissipation factors, dielectric strength, volume resistivity, tensile strength, tensile modulus, elongation, compressive strength, flexural strength, impact strength, hardness, heat distortion, coefficient for thermal expansion, thermal conductivity, and flammability for some of the preceding insulators are shown in Table 11 below. 
     
       
         
               
             
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 11 
               
             
             
               
                   
               
               
                 Properties of Insulators 
               
             
          
           
               
                   
                 Poly 
                 Poly 
                 Poly 
                   
                   
                   
                   
                   
               
               
                   
                 ethylene, 
                 ethylene, 
                 ethylene, 
                   
                   
                   
                 Poly 
                 Tetra 
               
               
                   
                 low- 
                 med- 
                 high- 
                 Poly 
                 Poly 
                 Poly 
                 vinyl 
                 fluoro 
               
               
                 Material 
                 density 
                 density 
                 density 
                 propylene 
                 styrene 
                 sulfone 
                 chloride 
                 ethylene 
               
               
                   
               
             
          
           
               
                 Electrical properties: 
                   
                   
                   
                   
                   
                   
                   
                   
               
               
                 Arc resistance 
                 140 
                 200 
                 200 
                 185 
                 100 
                 122 
                 80 
                 &gt;200 
               
               
                 Dielectric constant 
               
               
                 60 Hz 
                 2.4 
                 2.4 
                 2.4 
                 2.6 
                 3.4 
                 3.1 
                 3.6 
                 2.1 
               
               
                 10 6  Hz 
                 2.4 
                 2.4 
                 2.4 
                 2.6 
                 3.2 
                 3.1 
                 3.3 
                 2.1 
               
               
                 10 9  Hz 
                 2.4 
                 2.4 
                 2.4 
                 2.6 
                 3.1 
                 3.1 
                 3.4 
                 2.1 
               
               
                 Dissipation factor 
               
               
                 60 Hz 
                 &lt;0.0005 
                 &lt;0.0005 
                 &lt;0.0005 
                 &lt;0.0005 
                 0.0004 
                 0.0008 
                 0.007 
                 &lt;0.0002 
               
               
                 10 6  Hz 
                 &lt;0.0005 
                 &lt;0.0005 
                 &lt;0.0005 
                 &lt;0.0005 
                 0.0004 
                 0.001 
                 0.009 
                 &lt;0.0002 
               
               
                 10 9  Hz 
                 &lt;0.0005 
                 &lt;0.0005 
                 &lt;0.0005 
                 &lt;0.0005 
                 0.0004 
                 0.005 
                 0.006 
                 &lt;0.0002 
               
               
                 Dielectric strength, 
                 420 
                 500 
                 550 
                 450 
                 300 
                 400 
                 3.75 
                 430 
               
               
                 V/mil step by step 
               
               
                 Volume resistivity, 
                 10 16   
                 10 16   
                 10 16   
                 10 16   
                 10 16   
                 10 17   
                 10 16   
                 10 18   
               
               
                 Ω · cm 
               
               
                 Mechanical properties: 
               
               
                 Tensile strength, lb/in. 2   
                 2,300 
                 3,500 
                 5,500 
                 5,500 
                 6,800 
                 10,200 
                 9,000 
                 4,500 
               
               
                 Tensile modulus, lb/in. 2   
                 0.35 
                 0.55 
                 1.5 
                 2.3 
                 4.5 
                 3.6 
                 6.0 
                 0.58 
               
               
                 × 10 5   
               
               
                 Elongation, % 
                 800 
                 600 
                 100 
                 700 
                 80 
                 100 
                 40 
                 400 
               
               
                 Flexural strength, 
                 7,000 
                 1,000 
                 8,000 
                 10,000 
                 15,400 
                 16,000 
               
               
                 lb/in. 2   
               
               
                 Impact strength, ft lb/m 
                 No break 
                 &gt;16 
                 20 
                 1.5 
                 8 
                 1.3 
                 20 
                 3.0 
               
               
                 of notch 
               
               
                 Hardness, Rockwell 
                   
                   
                   
                 R110 
                 R100 
                 R120 
               
               
                 Thermal properties: 
               
               
                 Heat-distortion temp. 
                 105 
                 120 
                 120 
                 145 
                 205 
                   
                 164 
                 &gt;250 
               
               
                 at 264 lb/in 2   
               
               
                 Maximum-use temp., 
                 212 
                 250 
                 250 
                 320 
                 175 
                   
                 175 
                 550 
               
               
                 ° F. 
               
               
                 Coefficient of thermal 
                 18 
                 16 
                 13 
                 10 
                 21 
                 6 
                 18 
                 10 
               
               
                 expansion, ° C. −1  × 10 −5   
               
               
                 Thermal conductivity, 
                 8.0 
                 10.0 
                 12.4 
                 2.8 
                 3.0 
                 6.2 
                 7.0 
                 6 
               
               
                 cal/S-cm ° C. 
               
               
                 Flammability, in./min 
                 1.04 
                 1.04 
                 1.04 
                 1.04 
                 1.0 
                 No burn 
                 No burn 
                 No burn 
               
               
                   
               
             
          
         
       
     
     Among the many advantages of the modular retractile telephone cords of the present invention are: 
     1. Superior performance. 
     2. Reduced sagging. 
     3. Smaller relaxed retracted and recovered lengths. 
     4. Excellent space saver. 
     5. Better visual appeal. 
     6. Simple to install. 
     7. Easy to use. 
     8. Less obtrusive. 
     9. Compact. 
     10. Convenient. 
     11. Attractive. 
     12. User friendly. 
     13. Strong. 
     14. Economical. 
     15. Reliable. 
     16. Safe. 
     17. Efficient. 
     18. Effective. 
     Although embodiments have been shown and described, it is to be understood that various modifications and substitutions, as well as rearrangements of parts and components, can be made by those skilled in the art, without departing from the normal spirit and scope of this invention.