Búsqueda Imágenes Maps Play YouTube Noticias Gmail Drive Más »
Iniciar sesión
Usuarios de lectores de pantalla: deben hacer clic en este enlace para utilizar el modo de accesibilidad. Este modo tiene las mismas funciones esenciales pero funciona mejor con el lector.


  1. Búsqueda avanzada de patentes
Número de publicaciónUS2401291 A
Tipo de publicaciónConcesión
Fecha de publicación28 May 1946
Fecha de presentación11 Jun 1943
Fecha de prioridad11 Jun 1943
Número de publicaciónUS 2401291 A, US 2401291A, US-A-2401291, US2401291 A, US2401291A
InventoresAlbert F Smith
Cesionario originalDu Pont
Exportar citaBiBTeX, EndNote, RefMan
Enlaces externos: USPTO, Cesión de USPTO, Espacenet
Racket string
US 2401291 A
Resumen  disponible en
Previous page
Next page
Reclamaciones  disponible en
Descripción  (El texto procesado por OCR puede contener errores)


. Filed June 11, 1943 IN VEN TOR A1. BERT/T5M/7H ATTORNEY Patented May 28, 1946 RACKET s'mmc Albert F. Smith, Westwood Manor, Wilmington, Del., assignor to E. I. du Pont de Nemours & Company, Wilmington, Del., a corporation of Delaware Application June 11, 1943, Serial No. 490,438

2 Claims.

This invention relates to coated nylon cords. More particularly, it relates to the coating of cords of multifilament nylon yarns t produce resilient, tough, high-impact strength, abrasionreslsting structures for use as athletic racket strings,

Although the cords of the invention are suitable for all uses where toughness, resilience, high-impact strength, abrasion-resistance, etc., are demanded, the invention will be discussed in terms of athletic racket strings, and particularly tennis racket strings, for convenience.

Tennis rackets strung with single strand nylon monofils, while vastly superior in most respects to rackets strung with gut, have had certain inferior playing qualities and other disadvantages attendant upon the use of such single strand nylon monofils. The disadvantages are apparently due to the physical structure and forma tion of the monofils. It has been found that Iangitudinal splitting of the monofils occurs after a certain length of time. The splitting is regarded as being due to the lowered transverse strength because of the high longitudinal orientation of the monofils. The splitting results from nicks which are caused by the contact of the taut string with the dirt and grit carried by the ball. In stringing a racket, the longitudinal strings are drawn across the transverse string with a force approximating 80-100 pounds to achieve the necessary final high string tension. The nylon monofil strings formerly used have been known to become weakened and to eventually break in play because of chipping orwearing at points where the strings cros each other. Thi failure may be caused by brittleness, surface flaws, the absence of symmetry throughout the length and structure of the filament, or grooving of the transverse filaments in stringing.

It is an object of this invention to produce nylon tennis racket strings superior to former nylon tennis strings and devoid of the abovestated objections.

It is a further object to produce nylon tennis strings which possess all of the desirable properties of the nylon of former tennis strings and, in addition, that elusive quality known as good playing characteristics.

Other objects will appear hereinafter.

The objects are accomplished by forming a cord of twisted nylon multifilament yarns and coating it to product a tough, seamless skin on the twisted cord structure.

Nylon tennis racket strings have heretofore been made exclusively of singl strand monofilamentary yarn since nylon multifilament yarns were considered obviously and wholly unsuited to such usages because of their ease of stretchability, their lack of requisite stifi'ness or body, as well as the extreme sensitivity of the exposed filaments to abrasive action.

An important discovery of this invention rests in the fact that multifilament nylon yarns, when corded to produce a balanced cord and coated, make entirely acceptable and even superior tennis strings. These new tennis strings inherently possess the resiliency and recovery from stretch of twisted yarns, the iron-like strength of nylon yarns and the abrasion-resistance afforded by the coating which are important prerequisites for satisfactory tennis strings.

The present invention is illustrated in the accompanying drawing forming a part of this specification and wherein:

Figure 1 is a top plan view of a tennis racket strung with strings embodying the principles of the instant invention;

Figure 2 is a cross-section of a string shown in Figure 1;

Figure 3 is an enlarged and exaggerated view of one embodiment of a string, the coating being omitted, and partly raveled to show th construction thereof; and

Figure 4 is an enlarged and exaggerated view of another embodiment of a string, the coating being omitted, and partly raveled to show the construction thereof.

Referring now to the drawing, the reference numeral I designates a tennis racket frame strung with strings 2. Each string. 2 consists of a cord 3 obtained by twisting together a plurality of strands 4, and each strand 4 is obtained by twisting together a plurality of nylon filaments 5. Th cord 3 is provided with a coating 6.

In order that the invention may be more clearly understood, the following are examples of the method of construction of these nylon tennis strings:

Example I 210-denier, 68-filament, l-turn S polyhexamethylene adipamide yarn 5 was treated in the relaxed condition with boiling water as i known in the art to increase the impact strength. Six ends of the yarn 5 were twisted together 6.2 turns 8 to yield the strand 4. Six ends of the strand 4 were then twisted together 2.? turns Z to form the cord 3. The cord 3, which weighed 0.85 gram per yard. was coated with a nylon solution to build up a coating 6 weighing approximately 0.37 gram'per solids content. The coating solution was appliedat the speed of 8 feet per minute and loose felt wipers on the, cord removed the excess coating. The coating was dried at about 90C. in a 12-foot oven and one dry pass was used after the -application of the last coat.

The cord so formed and'which wa composed of about 30% coating was then strung in a tennis racket frame and, after being experimentallyused' and tested'forover a period of a year under conditions of actual use, the racket exhibited'exceptionally good service and was considered superior to former nylon monofil strung rackets.

Etcample- 'I I' 30-denier filaments i of polyhexamethylene adipamide were treated with aqueous phenol as is understood in the art to improve the impact strength. Thirty-six ends. were twisted turns s and six ends of the resulting strand ,4 were.

twisted 4 turns Z to form the cord 3'. The corded structure ,was coated with N -methoxymethyl polyamicle,v made ff rom polyhexamethylene adipamide,-in an ethyl alcohol solution solids .content).. By successive coatings, a covering of about 28% of;the final .structure was produced.

The coated structure wasthen bakedat 120 C. for-3 minutes. When strung in atennis racket in the usual way, it was found to have excellent playing characteristics and,very long life.

The multifilament nylon; yarns which can be used in this invention are not limited to those disclosed in the foregoing examples .but include also all filaments comprisingfiber-forming synthetic linear polymers, especially those of the classes described-in U,S.;Batehts1l los. 2,071,250, 2,071,251, 2,071,253, 2,130,523, and 2,130,948, as well as those filaments comprising .the interpolymers of. U. S. Patents-Nos. 2,252,554 and 2,252,555. In other words, the invention is intended to include for the preparationof the filaments all water-insoluble and fiber-forming nylon superpolymers and interpolymersr ;The method of twisting and stranding the filaments given in the examples is merely illustrative of conventional-procedures used in making cords for tennisrackets,.andthe invention isnot meant to be limited thereto since. it is obvious-that there can bensed other. combinations of twists, number of ends for building up a cord, amount or direction .of twist of either the strand or cord or both, to produce a final cord. structure having the proper .balance to produce resilience, impact strength and abrasion-resistance.

As shown by the examples, the coating composition will preferably comprise any of the synthetic linear polyamides capable of forming coating compositions, such as, for example, the polyamidesand interpolyamides of the type mentioned in U. S. Patents Nos. 2,071,253 and 2,130,948.

The invention. is not: limited, however,- to the use of synthetic-linear polyamides as coatin compositions. Other coating compositions which produce well-adhering, tough, abrasion-resisting, flexible and fatigue-resisting covering can be used. Examples of other materials which may be used are polyesters,-polyacetals, polyesteramides,

polyurethanes, polythioureas and p ymeric ethylene. Properly plasticized polymeric methacrylates. polymeric acrylates, polyvinyl'butyral, vinyl chloride vinyl acetate interpolymers', alkyd resins, heat-hardenable phenol-formaldehyde resins, and cellulose derivatives or suitable mixtures of the above resins are also applicable.

While the exampleshave shown the coating to be approximately 30% of the cord structure, the coating may constitute -40% of the final cord structure without departing from the spirit and scope lof the invention.

e coating may be applied by any of theconventio'nal eoatingmethods, i. e.. spr y ppin extrusion; dispersion, etc. While a preference 4 has' been shown for the application of the coating by solvent methods, the invention-is not so limited.- Any technique which results in a uniform,

continuous. adherent coating is satisfactory. The tennis racket strings of this invention have exceptionally good playing characteristics.- Because of their structure, the strings possess greater resilience and flexibility, higher tensile and impact strengths, more highly abrasiveresisting coatings and longer playing life-than have been achieved heretofore. These-strings .also possess apronounced fatigue-resistance,

holding approximately the same string,- tension after a year of use. The strings of the invention when the string is pulled through sharp bends to prevent ,the loss of any of the desirable playing .characteristics or durability inthe. stringing operation.

The improved strings of ,this invention are, especially valuable in athletic rackets, suchas tennis, badminton, squash racketsand the like. 40 --f Since it is obvious that various changes. and modifications may be made in the above description without departingjfrom the nature: or spirit thereof, .this invention is not .restricted thereto except as set forth in the appended claims.

said' coating giving sufllcient protection-against abrasion when the string is pulled through sharp bends to prevent the loss of the desirable playing characteristics or durability in the stringing operation', said corded structure comprising-a plurality linear polyamide prepared fromhexamethylenediammonium adipate, hexamethylenediammm niuni sebacate andcaprolactam inthe ratio of 40:30:30, said coating iving sufllcient protection against abrasionwhen the stringis pulled through sharp bends to prevent the loss of the-undesirable playing characteristics orrdurability iii-the stringing.operation,'said corded structure comprising a plurality of strands twisted together, each strand comprising;a,plurality. of polyhexamethylene adipamidefilaments twisted together,

said coating constituting 20% to 910% by weight of said string.


Citada por
Patente citante Fecha de presentación Fecha de publicación Solicitante Título
US2483455 *12 Abr 19464 Oct 1949Clark Thread CoMethod of making thermoplastic sewing thread
US2536312 *12 Feb 19482 Ene 1951Saether OivinFishing line
US2539300 *18 Nov 194823 Ene 1951Us Rubber CoElastic yarn
US2545869 *17 Feb 194820 Mar 1951Plax CorpMultiple fiber strand
US2575753 *29 Dic 194820 Nov 1951Us Rubber CoMethod of producing chenillelike yarn
US2629909 *15 Abr 19503 Mar 1953Morey Paper Mill Supply CoPintle or the like structural element for hinged seams
US2649833 *14 Abr 194925 Ago 1953Ashaway Line & Twine MfgManufacture of lines for racquets
US2694601 *14 Jul 194816 Nov 1954Tokheim CorpLiquid dispensing device
US2735258 *9 Ago 195121 Feb 1956 Manufacture and construction of
US2769439 *28 Abr 19546 Nov 1956Layer Clarence LBow string
US2861417 *16 Jun 195425 Nov 1958Ashaway Line & Twine MfgManufacture of strings and the construction thereof
US2880568 *9 Sep 19537 Abr 1959Columbian Rope CoMethod of making synthetic fiber rope and rope produced thereby
US2900784 *15 Ene 195825 Ago 1959United States Steel CorpCord and article containing the same
US2900785 *18 May 195625 Ago 1959United States Steel CorpSix-wire strand
US2917891 *1 Sep 195322 Dic 1959Columbian Rope CoSynthetic rope structure and method of making same
US3024589 *6 Mar 195613 Mar 1962Dunlop Rubber CoMethod of making racket cord
US3093352 *6 Jun 196111 Jun 1963Douglas Aircraft Co IncPower absorbing systems and components for arresting aircraft
US3164952 *17 Jun 196312 Ene 1965Dunlop Rubber CoMethod of making tennis cords
US3176375 *20 Jun 19636 Abr 1965Scapa Dryers LtdMethod of making paper-machine felt
US3329172 *8 Jun 19644 Jul 1967Dayco CorpHose
US3738096 *9 Nov 197012 Jun 1973Ashaway Line & Twine MfgManufacture and construction of strings
US3920658 *23 Nov 197318 Nov 1975Benson Martin JamesCoated tennis string and process for coating
US4016714 *21 May 197512 Abr 1977Ashaway Line & Twine Mfg. Co.String construction
US4043555 *26 Feb 197623 Ago 1977Irradiated Strings, Inc.Racquet string and method
US4055941 *9 Dic 19761 Nov 1977E. I. Du Pont De Nemours And CompanyIntegrated string
US4168606 *31 May 197725 Sep 1979The Goodyear Tire & Rubber CompanyProcess for forming string
US4183200 *3 Oct 197715 Ene 1980Pepsico, Inc.Tennis racket string
US4231575 *23 Dic 19774 Nov 1980Mers KuttRacket stringing
US4449353 *6 Ago 198222 May 1984United States Tennis Gut Association, Inc.Gut string for sports rackets
US4565061 *12 Dic 198321 Ene 1986Durbin Enoch JString for rackets
US4805393 *22 Feb 198821 Feb 1989Reta Marcos AString construction for a sports racket
US4860531 *16 Dic 198729 Ago 1989Wells D PhillipsRacquet strings
US5327714 *30 Jul 199212 Jul 1994Prince Manufacturing, Inc.Synthetic string for sporting application
US6183499 *4 Ago 19996 Feb 2001Ethicon, Inc.Surgical filament construction
US74725354 May 20046 Ene 2009Casual Living Worldwide, Inc.Coreless synthetic yarns and woven articles therefrom
US747253629 Jun 20046 Ene 2009Casual Living Worldwide, Inc.Coreless synthetic yarns and woven articles therefrom
US747296129 Jul 20046 Ene 2009Casual Living Worldwide, Inc.Woven articles from synthetic yarns
US74766301 Abr 200513 Ene 2009Casual Living Worldwide, Inc.Woven articles from synthetic self twisted yarns
US770002228 Sep 200520 Abr 2010Casual Living Worldwide, Inc.Woven articles from synthetic self twisted yarns
US782397930 Ene 20092 Nov 2010Casual Living Worldwide, Inc.Woven articles from synthetic yarn
US789298929 Jul 200422 Feb 2011Casual Living Worldwide, Inc.Woven articles from synthetic self twisted yarns
US805290720 Abr 20108 Nov 2011Sun Isle Usa, LlcWoven articles from synthetic self twisted yarns
US8522473 *28 Dic 20063 Sep 2013Yoz-Ami CorporationColored yarn object, process for producing the same, and fishing line
US880812115 May 201319 Ago 2014Wilson Sporting Goods Co.Racquet configured with fewer cross strings than main strings
US8832992 *29 Nov 201116 Sep 2014Yoz-Ami CorporationColored yarn object, process for producing the same, and fishing line
US908974315 May 201328 Jul 2015Wilson Sporting Goods Co.Racquet configured with fewer cross strings than main strings
US20040031534 *11 Jun 200319 Feb 2004Sun Isle Casual Furniture, LlcFloor covering from synthetic twisted yarns
US20050106966 *29 Jul 200419 May 2005Sun Isle Casual Furniture, LlcWoven articles from synthetic yarns
US20050106974 *29 Jun 200419 May 2005Larry SchwartzCoreless synthetic yarns and woven articles therefrom
US20050106975 *29 Jul 200419 May 2005Sun Isle Casual Furniture, LlcWoven articles from synthetic self twisted yarns
US20050191923 *1 Abr 20051 Sep 2005Sun Isle Casual Furniture, LlcWoven articles from synthetic self twisted yarns
US20060021668 *28 Sep 20052 Feb 2006Sun Isle Usa, LlcWoven articles from synthetic self twisted yarns
US20060099867 *21 Dic 200511 May 2006Sun Isle Usa, LlcWoven articles from synthetic self twisted yarns
US20060116041 *9 Dic 20041 Jun 2006Sun Isle Casual Furniture, LlcYarn having lateral projections
US20060225399 *9 Jun 200612 Oct 2006Sun Isle Usa, LlcMethod of making furniture with synthetic woven material
US20060225400 *14 Jun 200612 Oct 2006Sun Isle Usa, LlcMethod of making furniture with synthetic woven material
US20070113956 *17 Ene 200724 May 2007Casual Living Worldwide, Inc. D/B/A Bji, Inc.Woven articles from synthetic yarns
US20090134685 *30 Ene 200928 May 2009Casual Living Worldwide, Inc. D/B/A Bji, Inc.Woven articles from synthetic yarn
US20100229456 *28 Dic 200616 Sep 2010Shigeru NakanishiColored Yarn Object, Process for Producing the Same, and Fishing Line
US20100242253 *20 Abr 201030 Sep 2010Casual Living Worldwide, Inc. D/B/A Bji, Inc.Woven articles from synthetic self twisted yarns
US20120070662 *29 Nov 201122 Mar 2012Shigeru NakanishiColored yarn object, process for producing the same, and fishing line
US20140329086 *31 Dic 20136 Nov 2014Hyundai Motor CompanyContinuous carbon fiber/thermoplastic resin fiber composite yarn and method for manufacturing the same
DE1703132A1 *5 Abr 196817 Feb 1972Osaka Gosen Co LtdSaite aus Kunststoff sowie Verfahren zu ihrer Herstellung
DE19638908C1 *23 Sep 19969 Abr 1998Lozetex Zwirne GmbhRacquet string
WO1989007670A1 *30 Ene 198924 Ago 1989Marcas Arturo RetaString construction for a sports racket
Clasificación de EE.UU.57/242, 273/DIG.600, 57/251, 473/524, 124/90
Clasificación internacionalA63B51/02, D02G3/40, D06M15/595, D02G3/44
Clasificación cooperativaD02G3/40, D06M15/595, D02G3/444, A63B51/02, Y10S273/06
Clasificación europeaD02G3/44D, D02G3/40, A63B51/02, D06M15/595