PEI particle foams for applications in aircraft interiors

Abstract

Polymer foams based on polyetherimides (PEIs) fulfill the legal specifications demanded by the aviation industry for aircraft interiors. Specifically, the demands on fire characteristics, stability to media and mechanical properties constitute a great challenge here. According to related art, suitable polymer foams are produced as semi-finished products. Reprocessing to give shaped articles is uneconomic in terms of time and material exploitation, for example by virtue of large amounts of cutting waste. The material is suitable in principle and can be processed to give particle foam mouldings. These mouldings can be produced without reprocessing in short cycle times and, hence, economically. Furthermore, this gives rise to new means of functional integration, for example by direct incorporation of inserts etc. in the foam, and with regard to freedom in terms of design.

1 . A polyetherimide (PEI) particle foam, wherein the PEI particle foam has a glass transition temperature between 180 and 215° C., and wherein a mean cell diameter of the PEI particle foam is less than 2 mm. 
     
     
         2 . The PEI particle foam according to  claim 1 , wherein the PEI particle foam has been obtained from a composition consisting of 80% to 99.5% by weight of PEI, 0.5% to 10% by weight of a blowing agent, and 0% to 10% by weight of additives. 
     
     
         3 . The PEI particle foam according to  claim 2 , wherein the additives are present in the composition and at least one selected from the group consisting of flame retardants, plasticizers, pigments, UV stabilizers, nucleating agents, impact modifiers, adhesion promoters, theology modifiers, chain extenders, fibres, nanoparticles, and a polymer component. 
     
     
         4 . The PEI particle foam according to  claim 2 , wherein the blowing agent is selected from the group consisting of an alcohol, a ketone, an alkane, an alkene, CO 2 , N 2 , water, an ether, an aldehyde, chemical blowing agents, and mixtures of two or more thereof. 
     
     
         5 . The PEI particle foam according to  claim 1 , wherein the PEI particle foam has a tensile strength according to ISO1926 of greater than 0.5 MPa, an elongation at break according to ISO1926 of between 8% and 12%, a shear modulus according to ASTM C273 at room temperature of greater than 8 MPa, a shear resistance according to ASTM C273 at room temperature of greater 0.45 MPa, a compressive modulus according to ISO 844 at room temperature of greater than 13 MPa, and a compressive strength according to ISO 844 at room temperature of greater than 0.4 MPa. 
     
     
         6 . (canceled) 
     
     
         7 . The PEI particle foam according to  claim 1 , wherein the mean cell diameter of the PEI particle foam is less than 500 μm. 
     
     
         8 . A process for producing the PEI particle foam according to  claim 1 , the process comprising:
 extruding a composition consisting of 80% to 99.5% by weight of PEI, 0.5% to 10% by weight of blowing agent, and 0% to 10% by weight of additives from an extruder with a perforated plate to give foamed pellets, where temperatures between intake zone and screw tip are within a range between 180 and 380° C., a temperature of the perforated plate is between 250 and 350° C., and a melt temperature on exit through the perforated plate is between 230 and 360° C., and   subsequently foaming the foamed pellets further to give the PEI particle foam.   
     
     
         9 . A process for producing the PEI particle foam according to  claim 1 , the process comprising:
 extruding a composition consisting of 90% to 100% by weight of PEI and 0% to 10% by weight of additives from an extruder with a perforated plate to give pellets, where the temperatures between intake zone and screw tip are within a range between 180 and 380° C., the temperature of the perforated plate is between 300 and 350° C., and the melt temperature on exit through the perforated plate is between 250 and 360° C.,   subsequently loading the pellets with a blowing agent in an autoclave in such a way that the pellets contain between 0.5% and 10% by weight of the blowing agent, thus producing blowing agent-laden pellets, and   foaming the blowing agent-laden pellets by expansion and/or by heating to a temperature exceeding 200° C. to give the PEI particle foam.   
     
     
         10 . A process for producing a composite part, comprising:
 bonding, sewing, or welding the PEI particle foam produced by the process according to  claim 8  to cover materials.   
     
     
         11 . A process for producing a composite part, comprising:
 foaming the PEI particle foam produced by the process according to  claim 8  with a cover material in such a way that the PEI particle foam is bonded thereto by adhesive bonding or welding.   
     
     
         12 . The process according to  claim 8 , further comprising:
 introducing the composition on exit from the extruder into an optionally heated mould, optionally containing cover materials, and foaming with shaping to give the PEI particle foam or a composite material.   
     
     
         13 . The process according to  claim 8 , wherein inserts and/or channels are incorporated into the PEI particle foam during the foaming. 
     
     
         14 . A process, comprising:
 incorporating the PEI particle foam according to  claim 1  in an aircraft construction.   
     
     
         15 . The process according to  claim 14 , wherein the aircraft is selected from the group consisting of a jet, a small aircraft, a helicopter, and a spacecraft. 
     
     
         16 . The process according to  claim 14 , wherein the PEI particle foam is incorporated in the interior of the aircraft. 
     
     
         17 . The process according to  claim 14 , wherein the PEI particle foam is incorporated in the exterior of the aircraft. 
     
     
         18 . The PEI particle foam according to  claim 1 , wherein the PEI particle foam has been obtained from a composition consisting of 80% to 99.5% by weight of PEI, 1% to 9% by weight of a blowing agent, and 1% to 5% by weight of additives. 
     
     
         19 . The PEI particle foam according to  claim 3 , wherein the polymer component is at least one selected from the group consisting of polyamides, polyolefins, polyesters, sulfur-based polymers, and poly(meth)acrylimide. 
     
     
         20 . An article molded from the PEI particle foam according to  claim 1 , wherein the article is used for an aircraft construction. 
     
     
         21 . The article according to  claim 20 , wherein the article as been installed in the interior of an aircraft.