Sealant composition and sealed electrical connectors

• US 5,691,399 A
• Filed: 05/31/1995
• Issued: 11/25/1997
• Est. Priority Date: 08/23/1991
• Status: Expired due to Term

• Current Assignee: The Whitaker Corporation (Meggitt PLC)
• Original Assignee: The Whitaker Corporation (Meggitt PLC)
• Inventors: Koblitz, Francis Frederick, Mellinger, Ricky Charles, Lynch, Thomas John
• Primary Examiner(s): MERRIAM, ANDREW EDWIN
• Application Number:
  US08/455,333
• Time in Patent Office: 909 Days
• Field of Search: 525/100, 525/106, 523/173, 528/15, 528/31, 528/32, 524/731, 524/862
• US Class Current: 523/173
• CPC Class Codes: C08L 2666/02 Organic macromolecular compounds, natural resins, waxes or and bituminous materials
• CPC Class Codes: C08L 2666/24 Graft or block copolymers according to groups C08L51/00, C08L53/00 or C08L55/02; Derivatives thereof
• CPC Class Codes: C08L 53/00 Compositions of block copolymers containing at least one sequence of a polymer obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
• CPC Class Codes: C08L 53/005 Modified block copolymers
• CPC Class Codes: C08L 53/02 of vinyl-aromatic monomers and conjugated dienes
• CPC Class Codes: C08L 53/025 modified
• CPC Class Codes: C09K 2200/0247 Silica
• CPC Class Codes: C09K 2200/0405 Hydrocarbons
• CPC Class Codes: C09K 2200/06 Macromolecular organic compounds, e.g. prepolymers
• CPC Class Codes: C09K 2200/0617 Polyalkenes
• CPC Class Codes: C09K 2200/062 Polyethylene
• CPC Class Codes: C09K 2200/0632 Polystyrenes
• CPC Class Codes: C09K 2200/0642 Copolymers containing at least three different monomers
• CPC Class Codes: C09K 3/10 Materials in mouldable or extrudable form for sealing or packing joints or covers filling pastes C09D5/34
• CPC Class Codes: H01B 7/282 Preventing penetration of fluid , e.g. water or humidity, into conductor or cable
• CPC Class Codes: H01B 7/285 by completely or partially filling interstices in the cable
• CPC Class Codes: H01B 7/292 using material resistant to heat
• CPC Class Codes: H01R 13/5216 characterised by the sealing material, e.g. gels or resins
• CPC Class Codes: H01R 4/2495 Insulation penetration combined with permanent deformation of the contact member, e.g. crimping
• CPC Class Codes: H01R 4/70 Insulation of connections end caps H01R4/22
• CPC Class Codes: Y10S 439/936 : Potting material or coating, e.g. grease, insulative coating, sealant or, adhesive
• CPC Class Codes: Y10S 525/903 : Interpenetrating network

Abstract

Disclosed are sealant compositions having excellent slump and spew resistant, even at relatively high operating temperatures for electrical connectors. The sealants, which are flowable at such elevated temperatures, comprise two essential components: elastomeric thermoplastic polymer, preferably an organic polymer composite comprising diblock and triblock copolymers, and extender for the polymer. The extender may comprise a primary and a secondary extender, such as polybutene oil and mineral oil, respectively.

Claims

1. A method for preparing a sealant composition comprising the steps of:

(a) heating a composition including an elastomeric thermoplastic polymer and an extender to the gelation initiation temperature of the composition, said elastomeric thermoplastic organic polymer being elastomeric at ambient temperatures and flowable yet thermally stable at elevated temperatures in its neat uncompounded state, said elastomeric thermoplastic organic polymer comprising at least one elastomeric block and one non-elastomeric block; and

(b) substantially subsequent to said heating step, adding to said composition precursors for a crosslinkable polymer, the crosslinkable polymer having inorganic elements making up at least a portion of the backbone of the polymer chain and reacting said precursors under conditions of time and temperature sufficient to cause chemical crosslinking of said precursors.

2. The method of claim 1 wherein said gelation initiation temperature is from about 125°

C. to about 200°

C.

3. The method of claim 2 wherein said gelation initiation temperature is about 190°

C.

4. The method of claim 1 wherein said precursors include a crosslinking catalyst.

5. The method of claim 4 wherein said crosslinking catalyst comprises a platinum crosslinking catalyst.

6. The method of claim 1 wherein step (b) is performed after reaching the gelation end point of the elastomeric thermoplastic polymer and extender composition.

7. The method of claim 1 wherein said precursor for a crosslinkable polymer comprises first and second silicon-containing polymers, said silicon-containing polymers comprising silicone atoms present in the backbone either alone or with other atoms.

8. The method of claim 7 wherein said first silicon-containing polymer is a hydrosilicon-containing polymer and said second silicon-containing polymer is a vinyl functionalized silicon-containing polymer.

9. A method for preparing a sealant composition comprising the steps of:

(a) heating a solution including an elastomeric thermoplastic polymer and an extender to the gelation initiation temperature of said solution, said elastomeric thermoplastic organic polymer being elastomeric at ambient temperatures and flowable yet thermally stable at elevated temperatures in its neat uncompounded state, said elastomeric thermoplastic organic polymer comprising at least one elastomeric block and one non-elastomeric block; and

(b) substantially subsequent to said heating step, adding to said solution precursors for a crosslinkable polymer, the crosslinkable polymer having inorganic elements making up at least a portion of the backbone of the polymer chain, and reacting said precursors under conditions of time and temperature sufficient to cause chemical crosslinking of said precursors.

10. A method for preparing a sealant composition comprising the steps of:

(a) heating a dispersion including an elastomeric thermoplastic polymer and an extender to the gelation initiation temperature of said dispersion, said elastomeric thermoplastic organic polymer being elastomeric at ambient temperatures and flowable yet thermally stable at elevated temperatures in its neat uncompounded state, said elastomeric thermoplastic organic polymer comprising at least one elastomeric block and one non-elastomeric block; and

(b) substantially subsequent to said heating step, adding to said dispersion precursors for a crosslinkable polymer, the crosslinkable polymer having inorganic elements making up at least a portion of the backbone of the polymer chain, and reacting said precursors under conditions of time and temperature sufficient to cause chemical crosslinking of said precursors.

11. A method for preparing a sealant composition comprising the steps of:

(a) heating an emulsion including an elastomeric thermoplastic polymer and an extender to the gelation initiation temperature of said emulsion, said elastomeric thermoplastic organic polymer being elastomeric at ambient temperatures and flowable yet thermally stable at elevated temperatures in its neat uncompounded state, said elastomeric thermoplastic organic polymer comprising at least one elastomeric block and one non-elastomeric block; and

(b) substantially subsequent to said heating step, adding to said emulsion precursors for a crosslinkable polymer, the crosslinkable polymer having inorganic elements making up at least a portion of the backbone of the polymer chain, and reacting said precursors under conditions of time and temperature sufficient to cause chemical crosslinking of said precursors.