Flame-retardant polyamide filaments and their use

Abstract

A flame retardant polyamide filament comprising a polyamide resin composition which has a tensile strength of not less than 2.0 cN/dtex as measured according to JIS L1013 and comprises 98 to 80 parts by weight of a polyamide resin having a relative viscosity of 2.0 to 4.0 and 2 to 20 parts by weight of a triazine-based flame retardant which is dispersed in the polyamide filament and has an average particle size of less than 5 μm. Such a flame retardant polyamide filament is not required to contain any halogen-based compound and, therefore, can exhibit a high safety to environments and an excellent strength. Accordingly, the polyamide filament is suitable for production of a multi-filament, especially polyamide BCF obtained by crimping the multi-filament, and further carpets using the polyamide BCF. Also, the polyamide filament in the form of a monofilament is applicable to guard nets for wire harness, mesh sheets, etc., and the polyamide filament in the form of a multi-layer filament is also applicable to mesh sheets.

What is claimed is:  
     
         1 . A flame retardant polyamide filament comprising a polyamide resin composition which has a tensile strength of not less than 2.0 cN/dtex as measured according to JIS L1013 and comprises 98 to 80 parts by weight of a polyamide resin having a relative viscosity of 2.0 to 4.0 and 2 to 20 parts by weight of a triazine-based flame retardant which is dispersed in the polyamide filament and has an average particle size of less than 5 μm.  
     
     
         2 . A flame retardant polyamide filament according to  claim 1 , wherein the polyamide filament contains no halogen compound.  
     
     
         3 . A flame retardant polyamide filament according to  claim 1  or  2 , wherein the triazine-based flame retardant is a reaction product produced by reacting cyanuric acid with melamines at an equimolar ratio.  
     
     
         4 . A flame retardant polyamide filament according to any of  claims 1  to  3 , wherein an oxygen index (LOI) of the polyamide filament is not less than 27 as measured according to JIS K7201.  
     
     
         5 . A flame retardant polyamide filament according to any of  claims 1  to  4 , wherein the polyamide filament is in the form of a multi-filament comprising a plurality of monofilaments.  
     
     
         6 . A flame retardant polyamide filament according to  claim 5 , wherein the monofilament has a fineness of 4 to 90 dtex.  
     
     
         7 . A flame retardant polyamide filament according to any of  claims 1  to  4 , wherein the polyamide filament is in the form of a monofilament having a fineness of 300 to 56,500 dtex.  
     
     
         8 . A flame retardant polyamide filament according to any of  claims 1  to  4 , wherein the polyamide filament is in the form of a monofilament having a fineness of 400 to 11,000 dtex.  
     
     
         9 . A flame retardant polyamide BCF (bulked continuous filament) produced by subjecting the flame retardant polyamide filament as defined in  claim 5  which is a multi-filament, to a crimping process.  
     
     
         10 . A carpet using the flame retardant polyamide BCF as defined in  claim 9 .  
     
     
         11 . A guard net for wire harness produced by knitting the flame retardant polyamide filament as defined in  claim 7  into a tubular shape around an electric cable.  
     
     
         12 . A mesh sheet produced by knitting the flame retardant polyamide filament as defined in  claim 8  into a net, said mesh sheet having a porosity representing a mesh size, of 20 to 30%, and a basis weight of 100 to 600 g/m 2 .  
     
     
         13 . A flame retardant multi-layer filament which has said multi-layer filament having a tensile strength of no less than 2.0 cN/dtex as measured according to JIS L1013 and comprises an inner layer constituted of a flame retardant polyamide resin layer A comprising a polyamide resin composition comprising 98 to 80 parts by weight of a polyamide resin having a relative viscosity of 2.0 to 4.0 and 2 to 20 parts by weight of a triazine-based flame retardant which has an average particle size of less than 5 μm and is dispersed in the filament; and 
 a surface layer formed on the inner layer and constituted of any one of the flame retardant polyamide resin layer A, a polyamide resin layer B having a composition other than that of the flame retardant polyamide resin layer A and a polyolefin resin layer C.  
 
     
     
         14 . A flame retardant multi-layer filament according to  claim 13 , wherein an oxygen index (LOI) of the multi-filament is not less than 27 as measured according to JIS K7201.  
     
     
         15 . A flame retardant multi-layer filament according to  claim 13  or  14 , wherein a melting point of the polyamide resin contained in the polyamide resin layer A constituting the inner layer is higher by 5° C. or more, than a melting point of the resin used in the surface layer.  
     
     
         16 . A mesh sheet produced by interlacing the multi-layer filaments as defined in  claim 15  into a net, and heat-fusing crossing portions of the warp and weft filaments at the surface layer thereof.