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EP-4218697-B1 - EARPLUG ASSEMBLY AND METHOD FOR FORMING THE SAME

EP4218697B1EP 4218697 B1EP4218697 B1EP 4218697B1EP-4218697-B1

Inventors

  • ELY, JACOB
  • TEETERS, KENNETH F.
  • COFFIN, ROBERT C.
  • CAI, FENG

Dates

Publication Date
20260513
Application Date
20180830

Claims (15)

  1. A method for preparing an earplug assembly, the earplug assembly (1) comprising: a first earplug, a second earplug, , each earplug (10) comprising: a stem (100) having a proximal end (101), a distal end (102), and a longitudinal axis (A) extending from the proximal end to the distal end, the stem comprising a first thermoplastic having a first melting temperature; and a sound attenuating body (120) disposed at the distal end of the stem; and a cord (20) comprising a first end (21), a second end (22), and a length extending between the first and second ends, the cord comprising a second thermoplastic having a second melting temperature that is within 10°C of or lower than the first melting temperature; the method comprising attaching the first and second ends of the cord to the first and second earplugs, respectively, by: inserting a hot tip (3) to a depth (D111) into the proximal end of the stem of the respective first or second earplug to form a cord cavity (111), the hot tip having a temperature above the first and second melting temperatures; removing the hot tip from the stem; and inserting the respective first or second end of the cord into the cord cavity to thermally bond the first or second end of the cord to the proximal end of the stem of the first or second earplug, respectively.
  2. The method of claim 1, wherein the inserting the first or second end (21, 22) of the cord (20) into the cord cavity (111) melts a portion of the end of the cord.
  3. The method of claim 1 or 2, wherein the method forms a ball-and-socket attachment of the end (21, 22) of the cord (20) in the cord cavity (111).
  4. The method of any one of claims 1 to 3, further comprising holding the end (21, 22) of the cord (20) in the cord cavity (111) for about 0.5 to about 4 seconds.
  5. The method of any one of claims 1 to 4, wherein the melting temperature of the second thermoplastic is lower than the melting temperature of the first thermoplastic by 20 °C or more.
  6. The method of any one of claims 1 to 5, wherein the first thermoplastic is selected from rigid thermoplastics having a flexural modulus of about 0.3 to about 12 GPa and/or wherein the second thermoplastic is selected from flexible thermoplastics having a type A shore hardness of about 25 to about 90.
  7. The method of any one of claims 1 to 6, wherein the first thermoplastic comprises polypropylene, polyethylene terephthalate, polybutylene terephthalate, nylon, polycarbonate, or a mixture thereof and/or the second thermoplastic comprises thermoplastic polyolefins, thermoplastic elastomers, ethylene vinyl acetate, flexible polyvinyl chloride, styrene-butadiene copolymer, polypropylene-based elastomers, or a mixture thereof.
  8. The method of any one of claims 1 to 7, wherein the hot tip (3) has a temperature of about 175 to about 425 °C.
  9. The method of any one of claims 1 to 8, wherein the hot tip (3) is removed from the stem (100) about 0.1 to about 2 seconds after inserting the hot tip.
  10. The method of any one of claims 1 to 9, wherein the hot tip (3) is inserted to a depth of about 2 to about 10 mm into the proximal end (101) of the stem (100).
  11. An earplug assembly (1) comprising: a first earplug and a second earplug, each earplug (10) comprising: a stem (100) comprising a proximal end (101), a distal end (102), and a longitudinal axis (A) extending from the proximal end to the distal end, the stem comprising a first thermoplastic having a first melting temperature; and a sound attenuating body (120) disposed at the distal end of the stem; and a cord (20) comprising a first end (21), a second end (22), and a length extending between the first and second ends, the cord comprising a second thermoplastic having a second melting temperature, the second melting temperature being within 10°C of or lower than the first melting temperature, the first and second ends of the cord being inserted into a cord cavity (111) in the proximal ends of the stems of the first and second earplugs, respectively, and being thermally bonded to and extending to a depth into the proximal ends of the stems of the first and second earplugs by thermal bonding, and the cord cavity of the first and second earplugs being formable by inserting a hot tip (3) into the proximal end of the stem of the respective first and second earplug, the hot tip having a temperature above the first and second melting temperatures.
  12. The earplug assembly (1) of claim 11, wherein the second melting temperature is lower than the first melting temperature by at least 20 °C.
  13. The earplug assembly (1) of claim 12, wherein the attachment of the cord (20) to the stem (100) is free of adhesives.
  14. The earplug assembly of claim 12 or 13, wherein the first thermoplastic comprises polypropylene, nylon, or a combination thereof.
  15. The earplug assembly of any one of claims 12 to 14, wherein the second thermoplastic is ethylene vinyl acetate, EVA.

Description

The present disclosure relates to earplug assemblies, e.g., push-to-fit earplugs, where two earplugs are connected by a cord, and methods of manufacturing the earplug assemblies. The use of hearing protective and noise attenuating devices is well known, and various types of devices have been considered. Such devices include earplugs and semi-aural devices partially or completely constructed of foam or rubber materials that are inserted into, or placed over, the ear canal of a user to physically obstruct the passage of sound waves into the inner ear. WO 98/06362 presents an acoustical hearing device comprising a foam, and at least one porous component which is mechanically bonded to the foam, where the mechanical bonding of the porous component arises during manufacture wherein the porous component is placed into a mold cavity as an insert, and a foam is formed within the mold so as to allow controlled penetration of the porous component during foaming and importantly, entrapped air in the closed cavity may pass through the porous component during manufacture, thereby allowing the porous component to act as a mold vent. Compressible or "roll-down" type earplugs generally comprise a compressible, resilient body portion and may be made of suitable slow recovery foam materials. The earplug may be inserted into the ear canal of a user by first rolling it between fingers to compress the body portion, then pushing the body portion into the ear canal, and subsequently allowing the body portion to expand to fill the ear canal. Push-to-fit type earplugs have also been considered, and may include a compressible attenuating portion and a stiff portion (e.g., a stem) that extends from the attenuating portion. To insert a push-to-fit type earplug, the user grasps the stiff portion and pushes the attenuating portion into the ear canal with an appropriate level of force. The attenuating portion compresses as it is accommodated in the ear canal. Push-to-fit earplugs may allow the earplug to be quickly and easily inserted in an ear canal, and may promote hygiene by minimizing contact with the attenuating portion of the earplug prior to insertion. A pair of earplugs may be connected by a cord to form an earplug assembly. Although methods to attach the cord to the earplugs are known, they may be costly and may pose manufacturing challenges. US 4,293, 355 discloses a tethered earplug construction comprising a pair of plasticized thermoplastic foam earplugs tethered together by one or more flexible plasticized thermoplastic cord elements where attachment of the cord element to the earplug is achieved by ultrasonic welding. SUMMARY The invention is defined by the independent claims. The present disclosure relates to earplug assemblies where two earplugs, e.g., push-to-fit earplugs, are connected by a cord, and methods of manufacturing earplug assemblies. In one aspect a method of providing an earplug assembly according to claim 1 is provided. The earplug assembly comprises a first earplug, a second earplug, and a cord comprising a first end, a second end, and a length extending between the first and second ends, each earplug comprising a stem having a proximal end, a distal end, and a major outer surface and a longitudinal axis extending from the proximal end to the distal end; and a sound attenuating body disposed at the distal end of the stem, wherein the stem comprises a first thermoplastic having a first melting temperature and the cord comprising a second thermoplastic having a second melting temperature that that is within 10°C of or lower than the first melting temperature. The method for preparing the earplug assembly comprises attaching the first and second ends of the cord to the first and second earplugs, respectively, by: inserting a hot tip to a depth into the proximal end of the stem of the earplug to form a cord cavity, the hot tip having a temperature above the first and second melting temperatures; removing the hot tip from the stem; and inserting the end of the cord into the cord cavity to thermally bond the end of the cord to the proximal end of the stem of the earplug. In another aspect, an earplug assembly according to claim 11 is provided. The earplug assembly comprises a first earplug and a second earplug, each earplug comprising: a stem comprising a proximal end, a distal end, and a longitudinal axis extending from the proximal end to the distal end, the stem comprising a first thermoplastic having a first melting temperature; and a sound attenuating body disposed at the distal end of the stem. The earplug assembly further comprises a cord comprising a first end, a second end, and a length extending between the first and second ends, the cord comprising a second thermoplastic having a second melting temperature, the second melting temperature being within 10°C of or lower than the first melting temperature. The first and second ends of the cord being are inserted into a cord cavity in the proximal ends of