Method and article for microwave bonding of splice closure

• US 5,245,151 A
• Filed: 11/27/1991
• Issued: 09/14/1993
• Est. Priority Date: 04/07/1989
• Status: Expired due to Term

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Fish, Brian J., Chamberlain, Craig S., Dressler, Daryl D.
• Primary Examiner(s): Reynolds, Bruce A.
• Assistant Examiner(s): HOANG, TU BA
• Application Number:
  US07/800,644
• Time in Patent Office: 657 Days
• Field of Search: 219/10.55 E, 219/10.55 F, 219/10.55 M, 219/10.57, 219/10.61 R, 219/10.61 A, 219/10.79, 219/7.5, 219/8.5, 219/10.55 R, 156/272.2, 156/272.4, 156/274.8, 174/41, 174/91, 174/92, 174/93, 428/323, 428/328, 220/420
• US Class Current: 219/759
• CPC Class Codes: B29C 65/1425 Microwave radiation
• CPC Class Codes: B29C 65/1435 at least passing through one of the parts to be joined, i.e. transmission welding
• CPC Class Codes: B29C 65/148 placed at the interface
• CPC Class Codes: B29C 65/1487 making use of light guides B29C65/1687 takes precedence
• CPC Class Codes: B29C 65/4815 Hot melt adhesives, e.g. thermoplastic adhesives
• CPC Class Codes: B29C 65/5014 being fibre-reinforced B29C65/5028 takes precedence
• CPC Class Codes: B29C 65/5057 positioned between the surfaces to be joined B29C65/5035 takes precedence
• CPC Class Codes: B29C 66/1122 Single lap to lap joints, i.e. overlap joints B29C66/45, B29C66/472, B29C66/52272 take precedence
• CPC Class Codes: B29C 66/1312 Single flange to flange joints, the parts to be joined being rigid the parts to be joined being flexible B29C66/133
• CPC Class Codes: B29C 66/4322 by joining a single sheet to itself B29C66/4332 takes precedence
• CPC Class Codes: B29C 66/49 Internally supporting the, e.g. tubular, article during joining B29C66/63 takes precedence
• CPC Class Codes: B29C 66/54 Joining several hollow-preforms, e.g. half-shells, to form hollow articles, e.g. for making balls, containers; Joining several hollow-preforms, e.g. half-cylinders, to form tubular articles
• CPC Class Codes: B29C 66/71 characterised by the composition of the plastics material of the parts to be joined welding bar compositions B29C65/125
• CPC Class Codes: B29C 66/7212 characterised by the composition of the fibres
• CPC Class Codes: B29C 66/7392 characterised by the material of at least one of the parts being a thermoplastic
• CPC Class Codes: B29K 2023/00 Use of polyalkenes or derivatives thereof as moulding material
• CPC Class Codes: B29K 2023/06 PE, i.e. polyethylene
• CPC Class Codes: B29K 2023/0633 LDPE, i.e. low density polyethylene
• CPC Class Codes: B29K 2023/0641 MDPE, i.e. medium density polyethylene
• CPC Class Codes: B29K 2023/065 HDPE, i.e. high density polyethylene
• CPC Class Codes: B29K 2309/08 : Glass
• CPC Class Codes: B29K 2995/0005 : Conductive
• CPC Class Codes: B65D 2581/3443 : Shape or size of microwave reactive particles in a coating or ink
• CPC Class Codes: B65D 2581/3445 : Microwave reactive adhesives, e.g. also used in valves or lids
• CPC Class Codes: B65D 2581/3448 : Binders for microwave reactive materials, e.g. for inks or coatings
• CPC Class Codes: B65D 2581/3464 : Microwave reactive material applied by ink printing
• CPC Class Codes: B65D 2581/3472 : Aluminium or compounds thereof
• CPC Class Codes: B65D 2581/3475 : Titanium nitride
• CPC Class Codes: B65D 2581/3479 : Other metallic compounds, e.g. silver, gold, copper, nickel
• CPC Class Codes: B65D 2581/3494 : Microwave susceptor B65D2581/3487 takes precedence
• CPC Class Codes: B65D 81/3446 : specially adapted to be heated by microwaves
• CPC Class Codes: H02G 1/14 : for joining or terminating cables
• CPC Class Codes: H05B 6/80 : Apparatus for specific applications stoves or ranges F24C7/02

Abstract

A method and article for microwave bonding of thermoplastic closures such as that used in splicing telecommunications wires. The article is a composite bonding material (CBM) having a thermoplastic matrix (preferably polyethylene) which is miscible with the thermoplastic material of the closure, and a plurality of microwave susceptor particles dispersed throughout the matrix. A strip is fashioned from the CBM and may be applied to the sealing edges of the closure. Upon application of microwave energy in an amount sufficient to heat the susceptors and cause both the CBM matrix and the adjacent portion of the closure to melt and flow together, a fusion bond is produced which seals the closure. If the closure is being used with a cable having an inner conductive layer or sheath, a second CBM may be used at this seal, having magnetically reactive susceptors.

Claims

1. A microwave heating tubular closure for receiving one end of a cable having a plurality of wires and for protecting a splice of wires, the closure having a top member and a bottom member, both of said members begin formed of a thermoplastic material and each having an essentially semicircular cross-section, said members being longitudinally attached by a hinge defining two sealing edge generally diametrically opposite said hinge, a first edge of said sealing edges begin on said top member and a second edge of said sealing edges being on said bottom member, wherein the improvement comprises:

a strip of composite bonding material formed of a plurality of susceptor particles dispersed in a matrix, each of said susceptor particles being constructed of a substrate which is essentially non-reflective of microwave energy, and a coating surrounding said substrate, said coating being substantially absorptive of microwave energy, said coating having a thickness in the range of 1-100 Angstroms and having an electrical conductivity in the range of 10^-6 to 10⁷ Ω

-cm, resulting in said susceptor particles having a bulk resistivity in the range of 10^-2 to 10⁸ Ω

-cm, and said matrix comprising a thermoplastic material which is miscible with said thermoplastic material of said members, said strip being placed between said sealing edges.

2. The closure of claim 1 wherein said hinge is integrally molded with said top and bottom members, and further comprising another strip of said composite bonding material placed along an inner surface of said hinge.

3. The closure of claim 1 wherein the closure additionally includes an end cap having a hole therein for receiving the cable, the cable having an outer jacket of thermoplastic material and an inner conductive layer adjacent the outer jacket, and further comprising a sleeve of magnetically reactive composite bonding material placed along an inner surface of said hole, said magnetically reactive composite bonding material being formed of a plurality of ferromagnetic susceptor particles dispersed in a matrix, said matrix comprising a thermoplastic material which is miscible with the thermoplastic material of the outer jacket of the cable.

4. The closure of claim 1 wherein said matrix is formed of polyethylene.

5. The closure of claim 3 wherein said end cap is attached to an inner surface of said bottom member, and a portion of a periphery of said end cap is adjacent to an inner surface of said top member when the closure is in a closed position, and further comprising another strip of said composite bonding material placed on said portion of said periphery of said end cap.

9. The closure of claim 5 wherein said matrix is formed of polyethylene.

6. A microwave heating tubular closure for receiving one end of a cable having a plurality of wires and for protecting a splice of wires, the closure having essentially identical top and bottom members formed of a thermoplastic material, each member having at least one longitudinal flange extending outwardly from the closure, and said top member positionable against said bottom member whereby flanges form an adjacent strip, wherein the improvement comprises:

a strip of composite bonding material formed of a plurality of susceptor particles dispersing a matrix, each of said susceptor particles being constructed of a substrate which is essentially non-reflective of microwave energy, said substrate having a coating thereon which is substantially absorptive of microwave energy, said coating having a thickness in the range of 1-100 Angstroms and having an electrical conductivity in the range of 10^-6 to 10⁷ Ω

-cm, resulting in said susceptor particles having a bulk resistivity in the range of 10^-2 to 10⁸ Ω

-cm, and said matrix comprising a thermoplastic material which is miscible with said thermoplastic material of said members, said strip being placed between said pair of adjacent flanges.

7. The closure of claim 6 wherein each of said members has two flanges, defining a second pair of adjacent flanges in said closure, and further comprising another strip of said composite bonding material placed between said second pair of adjacent flanges.

8. The closure of claim 6 wherein the closure additionally includes an end cap having a hole therein for receiving the cable, the cable having an outer jacket of thermoplastic material and an inner conductive layer adjacent the outer jacket, and further comprising a sleeve of magnetically reactive composite bonding material placed along an inner surface of said hole, said magnetically reactive composite bonding material being formed of a plurality of ferromagnetic susceptor particles dispersed in a matrix, said matrix comprising a thermoplastic material which is miscible with the thermoplastic material of the outer jacket of the cable.

10. The closure of claim 8 wherein said end cap is attached to an inner surface of said bottom member, and a portion of a periphery of said end cap is adjacent to an inner surface of said top member when the closure is in an assembled state, and further comprising another strip of said composite bonding material placed on said portion of said periphery of said end cap.