Method for Producing Duroplastic Fine-Fiber Non-Wovens Having a High Flame-Retardant, Thermal Protective and Sound Insulating Effect

Abstract

The invention relates to a method for producing duroplastic fine-fiber non-wovens, characterized in that: a) melts of reactive three-dimensionally cross-linkable, non-linear prepolymers are extruded by nozzles; b) the exiting melts are blown by means of hot air to form fine fibers; c) the fine fibers are separated by the flow of air and deposited to form a non-woven comprised of a fine-fiber weave; d) the non-woven is subsequently compacted, and; e) the non-woven is treated with a medium that initiates a three-dimensional cross-linking, and the fine fibers in the non-woven are inherently bonded and/or hardened in a subsequent thermal post-hardening. This enables duroplastic fine-fiber non-wovens to be economically produced that have both a high flame retardant effect as well as a high thermal protection, sound insulation and filtering capacity.

1 . A process for producing thermoset microfibrous webs, comprising:
 a) melts of reactive, three-dimensionally crosslinkable, nonlinear prepolymers are pressed through dies,   b) the exiting melts are attenuated by hot air to form microfibers,   c) the microfibers are separated from the air stream and are deposited to form a web consisting of a microfibrous braid,   d) the web is subsequently compacted,   e) treated with a medium inducing a three-dimensional crosslinking and in a subsequent thermal postcure the microfibers in the web are self-bonded and/or cured off.   
   
   
       2 . The process according to  claim 1 , wherein reactive, nonlinear prepolymers three-dimensionally crosslinkable by a condensation reaction are pressed through dies situated in the tip of cones. 
   
   
       3 . The process according to  claim 2 , wherein the exiting melt is attenuated directly at the die outlet to form microfibers by the hot air, whose temperature is above the starting temperature of the condensation reaction, flowing at a high rate of speed along the tips of the die cones. 
   
   
       4 . The process according to  claim 2 , wherein the microfibers are separated from the air stream and are deposited as an unconsolidated web (random-laid ply). 
   
   
       5 . The process according to  claim 4 , wherein the unconsolidated web is subsequently compacted. 
   
   
       6 . The process according to  claim 4 , wherein the unconsolidated web has air comprising a component catalyzing the crosslinking flowing through it at temperatures below the melting point of the prepolymer. 
   
   
       7 . The process according to  claim 4 , wherein the unconsolidated web subsequently has an inert medium flow through it and, in the process, the catalyzing component is completely removed from the spaces between the fibers or if appropriate neutralized with a basic gas. 
   
   
       8 . The process according to  claim 4 , wherein the unconsolidated web is self-bonded and/or cured off to a consolidated web by elevating the temperature. 
   
   
       9 . The process according to  claim 8 , wherein the web has hot air flow through it and, in the process, is incrementally or continuously further heated. 
   
   
       10 . The process according to  claim 8  wherein the web is dwelled at high temperatures. 
   
   
       11 . The process according to  claim 1 , wherein the reactive crosslinkable, nonlinear prepolymers consist of alcohol-etherified melamine-formaldehyde resins. 
   
   
       12 . The process according to  claim 11 , wherein the alcohol-etherified melamine-formaldehyde resins consist of meltable 4- to 18-nucleus oligotriazine ethers in which the triazine segments contain 
     
       
         
         
             
             
         
       
       R 1 =—NH 2 , —NH—CHR 2 —O—R 3 , —NH—CHR 2 —O—R 4 —OH, —CH 3 , —C 3 H 7 , —C 6 H 5 —OH, phthalimido-,
 succinimido-, —NH—CO- C5-C18 -alkyl, —NH—C 5 -C 18 -alkylene-OH 
 
     
     
       
         
         
             
             
         
       
       
         —NH—CHR 2 —O—R 4 —O—CHR 2 —NH—, —NH—CHR 2 —NH—, —NH—CHR 2 —O—C 5 -C 18 -alkylene-NH—, 
         —NH—C 5 -C 18 -alkylene-NH—, —NH—CHR 2 —O—CHR 2 —NH—, 
       
       R 2 ═H, C 1 -C 7 -alkyl; 
       R 3 =C 1 -C 18 -alkyl, H; 
       R 4 =C 2 -C 18 -alkylene, —[CH 2 —CH 2 —O—CH 2 —CH 2 ] n —, —[CH 2 —CH(CH 3 )—O—CH 2 —CH(CH 3 )] n —,
 —[—O—CH 2 —CH 2 —CH 2 —CH 2 —] n —, 
 —[(CH 2 ) 2-8 —O—CO- C6-C12 -aryl-CO—O—(CH 2 ) 2-8 —] n —, 
 —[(CH 2 ) 2-8 —O—CO- C6-C12 -alkylene-CO—O—(CH 2 ) 2-8 -] n —, 
 where n=1 to 200; 
 
       sequences containing siloxane groups, of the type 
       C 1 -C 4 -alkyl C 1 -C 4 -alkyl, —(C 1 -C 18 )-alkyl-O—Si—O—[Si—] 1-4 —O—(C 1 -C 18 )-alkyl-, 
       C 1 -C 4 -alkyl, C 1 -C 4 -alkyl 
       polyester sequences containing siloxane groups, of the type 
       -[(A) r -O—CO—(B) s —CO—O-(A) r ]-, in which 
       A={(CH 2 ) 2-8 —O—CO—(C 6 -C 14 )-arylene-CO—O—(CH 2 ) 2-8 —} or
 —{(CH 2 ) 2-8 —O—CO—(C 2 -C 12 )-alkylene-CO—O—(CH 2 ) 2-8 —}; 
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
 
       B=—{(C 6 -C 14 )-arylene-CO—O-—({Si—O—[Si—O] y —CO—(C 6 -C 14 )-arylene-}
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl or 
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
 {O—CO—(C 2 -C 12 )-alkylene-CO—O—({Si—O—[Si—O], —CO—(C 2 -C 12 )-alkylene-CO—}; 
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
 r=1 to 70; s=1 to 70 and y=3 to 50; 
 
       polyether sequences containing siloxane groups, of the type 
       C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
       —CH 2 —CHR 2 —O—({Si—O—[Si—O] y —CHR 2 —CH 2 — 
       C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
       where R 2 ═H; C 1 -C 4 -alkyl and y=3 to 50; 
       sequences based on alkylene oxide adducts of melamine, of the type of 2-amino-4,6-di- C2-C4 -alkyleneamino-1,3,5-triazine sequences; 
       phenol ether sequences based on dihydric phenols and C 2 -C 8  diols, of the type of —C 2 -C 8 -alkylene-O—(C 6 -C 18 )-arylene-O—(C 2 -C 8 )-alkylene-sequences; 
       are linked by bridge members —NH—CHR 2 —O—R 4 —O—CHR 2 —NH— and —NH—CHR 2 —NH— and also, where appropriate, —NH—CHR 2 —O—CHR 2 —NH—, —NH—CHR 2 —O—C 5 -C 18 -alkylene-NH— and/or —NH—C 5 -C 18 -alkylene-NH— to form 4- to 18-nucleus oligotriazine ethers of linear and/or branched structure, the terminal triazine segments in the oligotriazine ethers forming triazine segments of the structure 
     
     
       
         
         
             
             
         
       
       Y=—NH—CHR 2 —O—R 3 , —NH—CHR 2 —O—R 4 —OH and also if appropriate —NH—
 CHR 2 —O—C 5 -C 18 -alkylene-NH 2 , 
 —NH—C 5 -C 18 -alkylene-NH 2 , —NH—C 5 -C 18 -alkylene-OH, 
 
       R 1 =—NH 2 , —NH—CHR 2 —O—R 3 , —NH—CHR 2 —O—R 4 —OH, —CH 3 , —C 3 H 7 , —C 6 H 5 , —OH, phthalimido-,
 succinimido-, —NH—CO—R 3 , —NH—C 5 -C 18 -alkylene-OH, —NH—C 5 -C 18 -alkylene-NH 2 , 
 
     
     
       
         
         
             
             
         
       
       R 2 =H, C 1 -C 7 -alkyl; 
       R 3 =C 1 -C 18 -alkyl, H; 
       R 4 =C 2 -C 18 -alkylene, —[CH 2 —CH 2 —O—CH 2 —CH 2 ] n —,-[CH 2 —CH(CH 3 )—O—CH 2 —CH(CH 3 )] n —, —[—O—CH 2 —CH 2 —CH 2 —CH 2 —] n —, —[(CH 2 ) 2-8 —O—CO- c6-c12 -aryl-CO—O—(CH 2 ) 2-8 -] n —, —[(CH 2 ) 2-8 —O—CO- c6-c12 -alkylene-CO—O—(CH 2 ) 2-8 —] n —,
 where n=1 to 200; 
 
       sequences containing siloxane groups, of the type 
       C 1 -C 4 -alkyl C 1 -C 4 -alkyl, —(C 1 -C 18 )-alkyl-O—Si—O—[Si—] 1-4 —O—(C 1 -C 18 )-alkyl-, 
       C 1 -C 4 -alkyl, C 1 -C 4 -alkyl 
       polyester sequences containing siloxane groups, of the type 
       -[(A) r -O—CO—(B) s —CO—O-(A) r ]-, in which 
       A={(CH 2 ) 2-8 —O—CO—(C 6 -C 14 )-arylene-CO—O—(CH 2 ) 2-8 —} or
 —{(CH 2 ) 2-8 —O—CO—(C 2 -C 12 )-alkylene-CO—O—(CH 2 ) 2-8 —}; 
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
 
       B=—{(C 6 -C 14 )-arylene-CO—O—({Si—O—[Si—O] y —CO—(C 6 -C 14 )-arylene-}
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl or 
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
 {O—CO—(C 2 -C 12 )-alkylene-CO—O—({Si—O—[Si—O], —CO—(C 2 -C 12 )-alkylene-CO—}; 
 C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
 r=1 to 70; s=1 to 70 and y=3 to 50; 
 
       polyether sequences containing siloxane groups, of the type 
       C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
       —CH 2 —CHR 2 —O—({Si—O—[Si—O] y —CHR 2 —CH 2 — 
       —C 1 -C 4 -alkyl C 1 -C 4 -alkyl 
       where R 2 ═H; C 1 -C 4 -alkyl and y=3 to 50; 
       sequences based on alkylene oxide adducts of melamine, of the type of 2-amino-4,6-di- C2-C4 -alkyleneamino-1,3,5-triazine sequences; 
       phenol ether sequences based on dihydric phenols and C 2 -Cdiolsa, of the type of —C 2 -C 8 -alkylene-O—(C 6 -C 18 )-arylene-O—(C 2 -C 8 )-alkylene-sequences; 
       in the oligotriazine ethers the molar ratio of the substituents R 3 :R 4 =20:1 to 1:20, the proportion of the linkages of the triazine segments through bridge members —NH—CHR 3 —O—R 4 —O—CHR 3 —NH— is 5 to 95 mol %. 
     
   
   
       13 . The process according to  claim 11  wherein the alcohol-etherified melamine-formaldehyde resins contain further compounds influencing the reactivity of the prepolymers and the molecular structure of the cured polymers. 
   
   
       14 . The process according to  claim 1 , wherein the reactive three-dimensionally crosslinkable, nonlinear prepolymers contain up to 20% by mass of further reactive polymers selected from the group consisting of ethylene copolymers, maleic anhydride copolymers, modified maleic anhydride copolymers, poly(meth)acrylates, polyamides, polyesters and polyurethanes. 
   
   
       15 . The process according to  claim 1 , wherein the reactive three-dimensionally crosslinkable, nonlinear prepolymers contain up to 20% by mass of aliphatic diols of the HO—R—OH type and also up to 2% by mass of fillers, color pigments, stabilizers, UV absorbers and/or auxiliaries. The process according to at least one of the aforementioned claims, characterized in that the reactive three-dimensionally crosslinkable, nonlinear prepolymers are before processing in the form of cylindrical, lenticular, pastille-shaped or spherical particles having an average diameter of 0.5 to 8 mm. 
   
   
       16 . The process according to  claim 1 , wherein the reactive, three-dimensionally crosslinkable, nonlinear prepolymers are melted at about 70° C. to 130° C. for spinning. 
   
   
       17 . The process according to  claim 1 , wherein the dies have a diameter of 0.1 to 3 mm. 
   
   
       18 . The process according to  claim 17 , wherein the dies have a diameter of 0.5 to 1 mm. 
   
   
       19 . The process according to  claim 1 , wherein the dies are situated on and/or in the tips of cones and the hot air flows along the die cones at a high rate of speed. 
   
   
       20 . The process according to  claim 19 , wherein the cones have an angle of 10 to 90°. 
   
   
       21 . The process according to  claim 1 , wherein the hot air, in particular the hot air flowing along the tips of the die cones at a high rate of speed, has a temperature of 150° C. to 400° C. 
   
   
       22 . The process according to  claim 21 , wherein the hot air, in particular the hot air flowing along the tips of the die cones at a high rate of speed, has a temperature of 180° C. to 300° C. 
   
   
       23 . The process according to  claim 1 , wherein the resulting fibers, in particular microfibers, are filaments or have a diameter/length ratio of greater than 1:50. 
   
   
       24 . The process according to  claim 1 , wherein the microfibers have an average diameter of 0.5 to 100 μm. 
   
   
       25 . The process according to  claim 24 , wherein the microfibers have an average diameter of 1 to 7 μm. 
   
   
       26 . The process according to  claim 1 , wherein the fibers have a disordered, small-scale crimped structure. 
   
   
       27 . The process according to  claim 1 , wherein the microfibers are separated from the air stream using a wire grid or braid inserted into the air/microfiber stream and at the same time an unconsolidated web forms. 
   
   
       28 . The process according to  claim 27 , wherein the wire grid or braid is in the form of an endless belt. 
   
   
       29 . The process according to  claim 27  wherein the air of the air/microfiber stream is aspirated away underneath the wire grid or braid. 
   
   
       30 . The process according to  claim 1 , wherein the web is compacted to the desired density by mechanical pressure or by forming. 
   
   
       31 . The process according to  claim 1 , wherein a three-dimensional crosslinking is induced or starts at temperatures below the microfiber melting point. 
   
   
       32 . The process according to  claim 1 , wherein the component inducing the three-dimensional crosslinking, in particular the component catalyzing the condensation reaction, is gaseous HCl and/or gaseous HBr and/or formic acid neat or diluted with air or some other inert gas. 
   
   
       33 . The process according to  claim 32 , wherein the microfibers in which the catalyzing components are sorbed self-bond in the temperature range between 100 and 120° C. 
   
   
       34 . The process according to  claim 1 , wherein the thermal postcure of the web is effected by incremental or continuous heating with hot air and at the same time, the methanol released is discharged together with detached HCI and/or HBr. 
   
   
       35 . The process according to  claim 34 , wherein the thermal postcure of the web is effected in the temperature range from 200° C. to 320° C. and preferably in the temperature range from 250° C. to 280° C. and the postcure time is between 15 min and 120 min and preferably between 20 min and 60 min. 
   
   
       36 . The process according to  claim 35 , wherein the web is washed with water after the postcure.