Thermoplastic fiber material spun from a raw material containing polyhydroxyether, methods for its production and uses for it

Abstract

The invention describes a new synthetic fiber material of polyhydroxyether, as well as a melt-spinning method for its production. The new material can be used, in particular, for stabilization of the reinforcement fibers of high-performance fiber composite materials before they are embedded in the matrix material. During this usage, the polyhydroxyether fiber material dissolves at a temperature above its glass transition temperature entirely in the matrix material, so that the reinforcement fibers can be arranged largely free of kinking. In addition, it forms cross-links with the matrix material to form a homogeneous matrix and thus does not constitute a disruptive third phase in the composite material. The compatibility of the matrix and reinforcement fiber is also improved. It was possible to improve the bending strength of test slabs by 12% as compared to that of reference slabs with polyester filament.

1 . Thermoplastic fiber material spun from a raw material containing polyhydroxyether, characterized in that the raw material contains polyhydroxyether as a single polymer, and the polyhydroxyether has an essential amorphous structure, a molecular weight Mw of 10,000 to 80,000 Dalton, and a glass transition temperature T g  of no more than 100° C.  
   
   
       2 . Thermoplastic fiber material per  claim 1 , characterized in that the polyhydroxyether has a molecular weight Mw of 20,000 to 60,000 Dalton and preferably between 30,000 and 55,000 Dalton.  
   
   
       3 . Thermoplastic fiber material per one of  claims 1  to  3 , characterized in that the polyhydroxyether has a glass transition temperature T g  less than 95° C. and preferably less than 90° C.  
   
   
       4 . Thermoplastic fiber material per  claim 3 , characterized in that the polyhydroxyether is chemically modified, preferably by grafting of short polycaprolactone side chains, in order to lowers its glass transition temperature T g  to a value between 30 and 80° C.  
   
   
       5 . Thermoplastic fiber material per one of  claims 1  to  4 , characterized in that it has a breaking strength greater than 5 cN/tex, preferably greater than 7 cN/tex and especially preferably greater than 9 cN/tex.  
   
   
       6 . Thermoplastic fiber material per one of  claims 1  to  5 , characterized in that it is or contains a monofilament with a titer of 20 to 12,000 dtex, preferably 100 to 3000 dtex, and especially preferably 200 to 1500 dtex.  
   
   
       7 . Thermoplastic fiber material per one of  claims 1  to  6 , characterized in that it is or contains a multifilament with a plurality of single filaments with an overall titer of 20 to 5000 dtex, preferably 100 to 1000 dtex.  
   
   
       8 . Thermoplastic fiber material per  claim 7 , characterized in that it is or contains a multifilament with 10 to 120, preferably 20 to 50 single filaments.  
   
   
       9 . Thermoplastic fiber material per one of  claims 1  to  5 , characterized in that it is or contains a staple fiber.  
   
   
       10 . Thermoplastic fiber material per  claim 9 , characterized in that it is further processed from staple fiber into ring yarn, compact yarn, rotor yarn or carded yarn.  
   
   
       11 . Thermoplastic fiber material per one of  claims 1  to  10 , characterized in that it is further processed into a two-dimensional textile form, such as a woven or knitted form, a fleece, a felt, or a scrim.  
   
   
       12 . Method for production of a thermoplastic fiber material according to one of  claims 1  to  11 , characterized in that it is a melt-spinning method and has the following features: 
 the temperature of the polyhydroxyether in the melt is 160 to 300° C.;    the pressure of the polyhydroxyether in the melt is 50 to 100 bar;    the dwell time of the polyhydroxyether in the melt is less than 15 minutes;    the cooling of the melt-spun material is organized effectively and adapted to the spinning temperature.    
   
   
       13 . Method per  claim 11 , characterized in that the temperature of the polyhydroxyether in the melt is 180-280° C. and preferably 190-240° C.  
   
   
       14 . Method according to one of claims  12  or  13 , characterized in that the dwell time of the polyhydroxyether in the melt is less than 10 minutes and preferably less than 8 minutes.  
   
   
       15 . Method according to one of  claims 12  to  14 , characterized in that an effective cooling of the melt-spun material adapted to the temperature of the polyhydroxyether in the melt is achieved as follows: 
 an injector plate is used with a capillary density less than 0.25 holes/cm 2 ;    the melt-spun material is cooled by blowing with air, and the blown air is first cooled to 10-20° C.;    the consumption of blown air is 200-300 m 3 /kg, when high spinning temperatures of at least 240° C. are used, and less than 200 m 3 /kg, when spinning temperatures less than 240° C. are used;    the convergence length is 4-6 m.    
   
   
       16 . Method according to one of  claims 12  to  15 , characterized in that it additionally has one or more of the following features: 
 one uses a injector plate with 10-100 capillaries, preferably 20-50 capillaries;    an injector plate is used with capillaries having diameter of 0.35-0.80 mm, preferably 0.40-0.60 mm;    the melt-spun material is drawn off at a speed between 800 and 1800 m/min, preferably between 1200 and 1600 m/min;    the melt-spun material is after-stretched by a factor of 1.1-1.8 to reduce the strain at fracture to below 150%, preferably below 100% and especially preferably below 80%;    the melt-spun material is wound at a speed of 1000-3000, preferably 1500-2500 m/min.    
   
   
       17 . Use of a thermoplastic fiber material according to one of  claims 1  to  11  in the making of structural parts from fiber composite materials with reinforcement fibers embedded in a matrix for securing of the reinforcement fibers in a defined geometrical arrangement before they are embedded in the matrix.  
   
   
       18 . Use per  claim 17 , characterized in that the reinforcement fibers are secured with a thread made from the thermoplastic fiber material, especially by embroidery, sewing and weaving techniques.  
   
   
       19 . Use according to one of claims  17  or  18 , characterized in that the reinforcement fibers are secured with a two-dimensional textile form made from the thermoplastic fiber material.  
   
   
       20 . Use according to one of  claims 17  to  19 , characterized in that the reinforcement fibers are at least partly melted to the thermoplastic fiber material at a temperature above its softening point.  
   
   
       21 . Use according to one of  claims 17  to  20 , characterized in that the reinforcement fibers consist of glass, carbon, aramide, polybenzoxazole, polybenzimidazole and/or other so-called “rigid rod” polymers.  
   
   
       22 . Use according to one of  claims 17  to  21 , characterized in that the matrix consists of a cross-linkable resin system, such as epoxy resin, unsaturated polyester resin, isocyanate ester resin, phenol resin, phenol-formaldehyde resin, melamine resin, or a combination of these resins.  
   
   
       23 . Use according to one of  claims 17  to  22 , characterized in that the cross-linkable resin system contains at least one of the following cross-linking components: 
 a polyisocyanate;    a carboxylic acid;    an anhydride, especially a cyclical anhydride;    a phenol resin, especially a butylated phenol resin;    a melamine resin, especially a methylated melamine resin;    a cyclical oxide resin and catalytic quantities of a strong acid.    
   
   
       24 . Use according to claims  22  or  23 , characterized in that the temperature during the hardening of the resin system is higher than the glass transition temperature T g  of the polyhydroxyether used in the thermoplastic fiber material.