Composite materials comprising honeycomb cores based on thermoplastic synthetic fiber non-wovens

Abstract

Composite materials are disclosed, including honeycomb cores based on thermoplastic synthetic fiber non-wovens. The invention concerns honeycomb cores based on thermoplastic synthetic fiber non-wovens, a method for manufacturing the honeycomb cores, as well as composite materials containing such honeycomb cores.

1 . Use of a spunbonded non-woven fabric based on thermoplastic organic synthetic fibers for manufacturing honeycomb core materials, wherein
 a) the spunbonded non-woven fabric used has a weight per unit area between 50 and 500 g/m 2 , preferably between 100 and 300 g/m 2 , wherein the preceding information refers to a spunbonded non-woven fabric without any chemical binders and other additives,   b) the spunbonded non-woven fabric used is made of fibers, which have a titer in the range of 1.0 to 20 dtex, preferably 1.5 to 10 dtex,   c) the spunbonded non-woven fabric used comprises no chemical binders,   d) the spunbonded non-woven fabric used comprises at least one thermoplastic binder, the melting point of which is at least 10° C., preferably at least 20° C., in particular at least 30° C. below the melting point of the fiber according to b), is however at least 170° C. so as to maintain the temperature resistance,   e) the spunbonded non-woven fabric used has an air permeability in the range of 5-2000 l/m 2  sec, preferably 100-300 l/m 2  sec @ 200 Pa measured according to EN-ISO 9237.   
     
     
         2 . The use according to  claim 1 , wherein the spunbonded non-woven fabric used has only fibers made of melt-spinnable, thermoplastic organic polymers, preferably with a melting point of at least 200° C. 
     
     
         3 . The use according to  claim 1 , wherein the spunbonded non-woven fabric used consists of fibers of polyamide, polycaprolactam, aromatic or partially aromatic polyamides, aliphatic polyamides, partially aromatic or fully aromatic polyesters, polyphenylene sulfide (PPS), polymers with ether and keto groups. 
     
     
         4 . The use according to  claim 1 , wherein the spunbonded non-woven fabric used is made of polyester, preferably of flame-retardantly modified polyester. 
     
     
         5 . The use according to  claim 1 , wherein the spunbonded non-woven fabric used has a maximum tractive force (in the longitudinal direction) of at least 100 N/5 cm, particularly preferably at least 200 N/5 cm, measured according to DIN 29073, Part 3. 
     
     
         6 . The use according to  claim 1 , wherein the spunbonded non-woven fabric used has a maximum tractive force (in the transverse direction) of at least 50 N/5 cm, particularly preferably at least 100 N/5 cm, measured according to DIN 29073, Part 3. 
     
     
         7 . The use according to  claim 1 , wherein the quantity of thermoplastic binder is 10-50% by weight, preferably 10-30% by weight, each with reference to the total weight of the spunbonded non-woven fabric. 
     
     
         8 . The use according to  claim 1 , wherein the thermoplastic binder is introduced in the form of a separate binder fiber, a granulate or in the form of the low-melting component of a bi-component fiber. 
     
     
         9 . The use according to  claim 1 , wherein the thermoplastic binder is selected from the group of polyesters and has a melting temperature that is decreased with respect to the nonwoven fabric raw material by 10 to 50° C., preferably 30 to 50° C. 
     
     
         10 . Honeycomb core material, wherein it was made from a spunbonded non-woven fabric, wherein
 a) the spunbonded non-woven fabric used has a weight per unit area between 50 and 500 g/m 2 , preferably between 100 and 300 g/m 2 , wherein the preceding information refers to a spunbonded non-woven fabric without any chemical binders and other additives,   b) the spunbonded non-woven fabric used is made of fibers, which have a titer in the range of 1.0 to 20 dtex, preferably 1.5 to 10 dtex,   c) the spunbonded non-woven fabric used comprises no chemical binders,   d) the spunbonded non-woven fabric used comprises at least one thermoplastic binder, the melting point of which is at least 10° C., preferably at least 20° C., in particular at least 30° C. below the melting point of the fiber according to b), is however at least 170° C. so as to maintain the temperature resistance,   e) the spunbonded non-woven fabric used has an air permeability in the area of the non-welded areas of the honeycomb cell in the range of 5-2000 l/m 2  sec, preferably 100-300 l/m 2  sec @ 200 Pa measured according to EN-ISO 9237.   
     
     
         11 . The honeycomb core material according to  claim 10 , wherein it has an edge stiffness of >1. 
     
     
         12 . The honeycomb core material according to  claim 10 , wherein it has a pressure resistance of >0.8 MPa for a volume weight of 20-70 kg/m 3 . 
     
     
         13 . The honeycomb core material according to  claim 10 , wherein the spunbonded non-woven fabric used, which comprises no chemical binders, is provided with at least a further binder in addition to the thermoplastic binder. 
     
     
         14 . A method for manufacturing the honeycomb core material according to  claim 10 , comprising the following steps:
 (a) providing a thermally mergeable spunbonded non-woven fabric ( 14 ),   (b) welding two web sections ( 14   a ) ( 16 ) of the thermally mergeable spunbonded non-woven fabric ( 14 ) through connecting a plurality of connecting sections ( 16 ),   (c) welding of the assembled web sections ( 14   a ), ( 14   b ) with a next web section ( 14   c ) according to the same method, wherein the new connecting sections ( 16 ) are arranged offset (H) with respect to the previously formed connecting sections ( 16 ),   (d) repetition of step (c) any number of times,   (e) heating of the compound obtained after step (d),   (f) fanning of the warmed up compound according to (e) towards the honeycomb core material ( 10 ),   (g) cooling down of the fanned-apart honeycomb core material ( 10 ) for fixing of the formed honeycomb cores,   wherein the spunbonded non-woven fabric used in step (a)   I) has a weight per unit area between 50 and 500 g/m 2 , wherein the preceding information refers to a spunbonded non-woven fabric without any chemical binders and other additives,   II) the spunbonded non-woven fabric is made of fibers, which have a titer in the range of 1.0 to 20 dtex, preferably 1.5 to 10 dtex,   III) the spunbonded non-woven fabric comprises no chemical binders,   IV) the spunbonded non-woven fabric comprises at least one thermoplastic binder, the melting point of which is at least 10° C., preferably at least 20° C., in particular at least 30° C. below the melting point of the fiber according to II), is however at least 170° C. so as to maintain the temperature resistance,   V) the spunbonded non-woven fabric has an air permeability in the range of 5-2000 l/m 2  sec, preferably 100-300 l/m 2  se c @ 200 Pa measured according to EN-ISO 9237, and   VI) the heating according to step e) to a temperature corresponding to the melting temperature of the thermoplastic binder resp. of the fusible binder fibers (lower limit) and at least 10° C. below the melting temperature of the carrier fibers (upper limit).   
     
     
         15 . A method for manufacturing the honeycomb core material according to  claim 10 , comprising the following steps:
 (a) providing a thermally mergeable spunbonded non-woven fabric ( 14 ),   (b) welding two web sections ( 14   a ) ( 16 ) of the thermally mergeable spunbonded non-woven fabric ( 14 ) through connecting a plurality of connecting sections ( 16 ),   (c) welding of the assembled web sections ( 14   a ), ( 14   b ) with a next web section ( 14   c ) according to the same method, wherein the new connecting sections ( 16 ) are arranged offset (H) with respect to the previously formed connecting sections ( 16 ),   (d) repetition of step (c) any number of times,   (e) fanning of the non-heated compound according to (d) towards the honeycomb core material ( 10 ),   (f) applying a chemical binder, preferably a self-cross-linking chemical binder, which hardens by chemical reaction, wherein application takes place prior to or during fanning according to (e),   (g) hardening of the binder applied according to (f) for fixing the formed honeycomb core,   wherein the spunbonded non-woven fabric used in step (a)   I) has a weight per unit area between 50 and 500 g/m 2 , wherein the preceding information refers to a spunbonded non-woven fabric without any chemical binders and other additives,   II) the spunbonded non-woven fabric is made of fibers, which have a titer in the range of 1.0 to 20 dtex, preferably 1.5 to 10 dtex,   III) the spunbonded non-woven fabric comprises no chemical binders,   IV) the spunbonded non-woven fabric comprises at least one thermoplastic binder, the melting point of which is at least 10° C., preferably at least 20° C., in particular at least 30° C. below the melting point of the fiber according to II), is however at least 170° C. so as to maintain the temperature resistance,   V) the spunbonded non-woven fabric has an air permeability in the range of 5-2000 l/m 2  sec, preferably 100-300 l/m 2  sec @ 200 Pa measured according to EN-ISO 9237.   
     
     
         16 . The use of the honeycomb core material according to  claim 10  for manufacturing sandwich-like composite materials. 
     
     
         17 . A composite material comprising:
 (i) at least one honeycomb core material and   (ii) at least two cover layers, which are bonded together in a planar manner, being separated by a honeycomb core material,   (iii) binding of the honeycomb core material and the cover layers has taken place by means of a binder,   wherein the honeycombs are made of a spunbonded non-woven fabric consolidated with a thermoplastic binder and   I) the spunbonded non-woven fabric has a weight per unit area between 50 and 500 g/m 2 , wherein the preceding information refers to a spunbonded non-woven fabric without any chemical binders and other additives,   II) the spunbonded non-woven fabric is made of fibers, which have a titer in the range of 1.0 to 20 dtex, preferably 1.5 to 10 dtex,   III) the spunbonded non-woven fabric comprises no chemical binders,   IV) the spunbonded non-woven fabric comprises at least one thermoplastic binder, the melting point of which is at least 10° C., preferably at least 20° C., in particular at least 30° C. below the melting point of the fiber according to II), is however at least 170° C. so as to maintain the temperature resistance,   V) the spunbonded non-woven fabric has an air permeability in the area of the non-welded areas of the honeycomb cell in the range of 5-2000 l/m 2  sec, preferably 100-300 l/m 2  sec @ 200 Pa measured according to EN-ISO 9237.   
     
     
         18 . Use of mixtures of monomer and/or oligomer compounds, which are converted by means of polymerization or polycondensation into thermoplastic polymers for the consolidation of honeycomb cores.