Polyester core materials and structural sandwich composites thereof

• US 7,951,449 B2
• Filed: 06/27/2002
• Issued: 05/31/2011
• Est. Priority Date: 06/27/2002
• Status: Active Grant

• Current Assignee: Airex AG (Schweiter Technologies AG)
• Original Assignee: Baltek Incorporated (Alcan)
• Inventors: Feichtinger, Kurt, Ma, Wenguang
• Primary Examiner(s): Vo; Hai
• Application Number:
  US10/183,841
• Publication Number:
  US 20040001946A1
• Time in Patent Office: 3,260 Days
• Field of Search: 428/317.9, 428/319.3, 428/319.7, 428/310.5, 428/319.1, 428/316.6, 428/318.8, 428/480
• US Class Current: 428/318.8
• CPC Class Codes: B29C 44/22 consisting of at least two parts of chemically or physically different materials, e.g. having different densities
• CPC Class Codes: B29C 44/468 in a plurality of parallel streams which unite during the foaming
• CPC Class Codes: B32B 2250/20 All layers being fibrous or filamentary
• CPC Class Codes: B32B 2262/101 Glass fibres
• CPC Class Codes: B32B 2262/103 Metal fibres
• CPC Class Codes: B32B 2262/106 Carbon fibres, e.g. graphite fibres
• CPC Class Codes: B32B 2266/0264 Polyester
• CPC Class Codes: B32B 2266/08 Closed cell foam
• CPC Class Codes: B32B 2307/73 Hydrophobic
• CPC Class Codes: B32B 3/26 characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids foam layer B32B5/18; layer of synthetic resin characterised by fillers that create voids or cavities B32B27/205; characterised by an apertured layer
• CPC Class Codes: B32B 5/18 characterised by features of a layer of foamed material
• CPC Class Codes: B32B 5/245 another layer next to it being a foam layer
• CPC Class Codes: B32B 7/05 the layers not being connected over the whole surface, e.g. discontinuous connection or patterned connection using interposed adhesives or bonding materials applied in spaced arrangements B32B7/14
• CPC Class Codes: C08J 2367/02 Polyesters derived from dicarboxylic acids and dihydroxy compounds; C08J2367/06 takes precedence
• CPC Class Codes: C08J 9/04 using blowing gases generated by a previously added blowing agent
• CPC Class Codes: C08J 9/365 Coating
• CPC Class Codes: E04C 2/292 composed of insulating material and sheet metal
• CPC Class Codes: E04C 2/296 composed of insulating material and non-metallic or unspecified sheet-material E04C2/288 takes precedence
• CPC Class Codes: Y10T 428/249976 Voids specified as closed
• CPC Class Codes: Y10T 428/249981 Plural void-containing components
• CPC Class Codes: Y10T 428/249986 : Void-containing component contains also a solid fiber or solid particle
• CPC Class Codes: Y10T 428/249989 : Integrally formed skin
• CPC Class Codes: Y10T 428/24999 : Inorganic
• CPC Class Codes: Y10T 428/249991 : Synthetic resin or natural rubbers
• CPC Class Codes: Y10T 428/249992 : Linear or thermoplastic
• CPC Class Codes: Y10T 428/31786 : Of polyester [e.g., alkyd, etc.]

Abstract

High-strength, chemically and thermally stable, closed-cell foams, useful as structural core materials in sandwich composites. The core materials of the invention display anisotropic properties. The core materials of the invention are amenable to vacuum-mediated resin bonding to composite skins to provide lightweight, high-strength structural sandwiches suitable for use in a variety of applications, such as marine applications, construction, aviation, rapid transit, and recreational vehicles.

Claims

1. A structural sandwich composite comprising:

a block of core material bonded to one or more structural skins, said skin made from a material selected from the group consisting of thermosetting polymer, thermoplastic polymer reinforced with glass fibers, metallic fibers, inorganic fibers, or carbon fibers;

thermosetting polymer reinforced with glass fibers, metallic fibers, inorganic fibers, or carbon fibers;

wood;

fiberglass; and

metal;

said core material comprising a plurality of foamed polyester strands rigidly bound to one another with substantially no inter-strand voids between the strands, and formed by extrusion through a multi-orifice die, said strands defining a plurality of discrete volumes, each discrete volume comprising an interior section and a corresponding jacket, wherein the average cell size in the interior section is larger than the average cell size in the jacket.

2. The structural sandwich composite of claim 1, wherein the core material is anisotropic.

3. The structural sandwich composite of claim 1, wherein the block is bonded between two structural skins.

4. The structural sandwich composite of claim 3, further comprising a resin bond between the block and the structural skin.

5. The structural sandwich composite of claim 1, wherein the foamed polyester core material is foamable polyethylene terephthalate, foamable polybutylene terephthalate, foamable polyethylene naphthalate, foamable copolymer of polyethylene terephthalate, a foamable copolymer of polybutylene terephthalate, a foamable copolymer of polyethylene naphthalate, or a mixture thereof.

6. The structural sandwich composite of claim 1, wherein the foamed polyester core material is formable polyethylene terephthalate.

7. The structural sandwich composite of claim 1, wherein the core material further comprises a nucleating agent, a fire retardant, or a reinforcing agent.

8. The structural sandwich composite according to claim 1, wherein the block of core materials is an end-strand panel bonded to one or more structural skins.

9. The structural sandwich composite according to claim 1, wherein the block of core materials are oriented in a flat-strand panel and bonded to one or more structural skins.

10. The structural sandwich composite according to claim 1, wherein the core materials are chemically or thermally bound to one another to form the block.