# US 10,441,471 B2 · Push-in earplug

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- Number: US 10,441,471 B2
- Document ID: US10441471B2
- Status: Granted
- Kind: B2
- Application number: 15/457,772
- Filed: 2017-03-13
- Published: 2017-06-29
- Granted: 2019-10-15
- Earliest claimed: 2012-07-12
- Assignees: 3M Innovative Properties Company
- Applicants: 3M Innovative Properties Company
- Inventors: James P. Endle; Jeffrey L. Hamer; Alan R. Seville; Kenneth F. Teeters
- Web page: https://patentgrep.com/patent/US10441471B2

## CPC

- A61F 11/08: internal, e.g. earplugs
- B29C 44/022: {Foaming unrestricted by cavity walls, e.g. without using moulds or using only internal cores}
- B29C 44/04: consisting of at least two parts of chemically or physically different materials, e.g. having different densities
- B29C 44/08: using several expanding {or moulding} steps
- B29C 44/26: using several expanding steps
- B29C 44/324: {the preformed parts being tubular or folded to a tubular shape}
- B29C 44/50: using pressure difference, e.g. by extrusion or by spraying {(B29C44/468 takes precedence)}
- B29C 44/507: {extruding the compound through an annular die (in general B29C48/03)}
- C08J 9/105: {containing sulfur}
- C08J 9/32: from compositions containing microballoons, e.g. syntactic foams
- A61F 11/085: {including an inner channel}
- B29K 2023/12: {PP, i.e. polypropylene}
- B29K 2105/04: cellular or porous
- B29L 2031/768: {Protective equipment (B29L2031/4821 takes precedence)}
- C08J 2203/04: N2 releasing, ex azodicarbonamide or nitroso compound
- C08J 2203/184: of chemical foaming agent and physical blowing agent, e.g. azodicarbonamide and fluorocarbon
- C08J 2203/22: Expandable microspheres, e.g. Expancel®
- C08J 2353/02: of vinyl aromatic monomers and conjugated dienes
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)
- B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00)
- C08J: WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H (working, e.g. shaping, of plastics B29)
- B29K: INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR {MOULDS, } REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29L: INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES

## Abstract

A push-in earplug including an elongate core and outer layer is disclosed. The outer layer includes a sound attenuating portion having a first average density and a stem portion having a second average density, and the second average density is greater than the first average density.

## Claims

### Claim 1

A method for forming an earplug having a stem portion and a sound attenuating portion, comprising:
providing a preform comprising (i) an elongate core comprising a first material and having first and second ends and an outer major surface; and (ii) an outer layer comprising a second material and covering at least a portion of the outer major surface of the elongate core, wherein the second material comprises expandable spheres including thermoplastic shells encapsulating a gas; and
expanding the spheres to expand the second material, wherein the second material in proximity to the first end of the elongate core is expanded to a greater extent than the second material in proximity to the second end of the elongate core,
wherein the expanded second material in proximity to the first end of the elongate core forms the sound attenuating portion of the earplug and wherein the second material in proximity to the second end of the elongate core forms the stem portion of the earplug.

### Claim 2 (depends on 1)

A method of claim 1, wherein the expanding the spheres to expand the second material results in the sound attenuating portion having a first average density ρ1 and the stem portion having a second average density ρ2, and wherein |ρ2>1.2 ρ1|.

### Claim 3 (depends on 1)

A method of claim 1, further comprising placing at least a portion of the preform in proximity to the second end of the elongate core into a mold configured to prevent the second material in proximity to the second end of the elongate core from expanding as much as the second material in proximity to the first end of the elongate core.

### Claim 4 (depends on 3)

A method according to claim 3, wherein the second material in proximity to the first end of the elongate core is expanded in the mold.

### Claim 5 (depends on 1)

The method of claim 1, wherein the elongate core comprises multiple layers, wherein at least one layer of the elongate core facilitates thermal bonding with the outer layer of the earplug.