Powdery composition of a polymer and a flameproofing agent containing ammonium polyphosphate, method for the production thereof, and moulded body produced from said powder

Abstract

The present invention relates to a powder which, in addition to a polymer, comprises a flame retardant based on ammonium polyphosphate, to the use of this powder for the layer-by-layer production of moldings, and also to moldings produced from this powder. The moldings constructed using the inventive powder have marked advantages with regard to their flammability, when comparison is made with conventional products, and this permits use in aircraft, for example. Furthermore, moldings produced from inventive powder also have improved mechanical properties, when comparison is made with moldings based on conventional powders, in particular in relation to modulus or elasticity and in relation to tensile strength. In addition, these moldings also have a density close to that of injection moldings.

1 . A pulverulent composition the pulverulent composition is a powder comprising: 
 at least one polymer; and    at least one flame retardant that comprises ammonium polyphosphate, wherein the powder has a maximum particle size of ≦150 μm.    
     
     
         2 . The pulverulent composition as claimed in  claim 1 , wherein the polymer is prepared by at least one of milling, precipitation, anionic polymerization, or by a combination of these, or by subsequent fractionation.  
     
     
         3 . The pulverulent composition as claimed in  claim 1 , wherein the polymer is at least one of a homopolymer or a copolymer selected from polyester, polyvinyl chloride, polyacetal, polypropylene, polyethylene, polystyrene, polycarbonate, poly-(N-methylmethacrylimides) (PMMI), polymethyl methacrylate (PMMA), ionomer, polyamide, copolyester, copolyamides, terpolymers, and acrylonitrile-butadiene-styrene copolymers (ABS), or is a mixture of these.  
     
     
         4 . The pulverulent composition as claimed in  claim 1 , wherein the polymer is nylon-6,12, nylon-11, nylon-12, or a copolymer of these polyamides.  
     
     
         5 . The pulverulent composition as claimed in  claim 1 , wherein the polymer has a melting point of from 50 to 350° C.  
     
     
         6 . The pulverulent composition as claimed in  claim 5 , wherein the polymer has a melting point of from 70 to 200° C.  
     
     
         7 . The pulverulent composition as claimed in  claim 1 , wherein the powder has a median particle size of from 20 to 100 μm.  
     
     
         8 . The pulverulent composition as claimed in  claim 1 , further comprising at least one auxiliary, filler, or pigment.  
     
     
         9 . The pulverulent composition as claimed in  claim 8 , which comprises a flow aid as an auxiliary.  
     
     
         10 . The pulverulent composition as claimed in  claim 1 , wherein the ammonium polyphosphate contains from 10 to 35% by weight of phosphorus.  
     
     
         11 . The pulverulent composition as claimed in  claim 1 , wherein the flame retardant component comprises a synergist with the ammonium polyphosphate.  
     
     
         12 . The pulverulent composition as claimed in  claim 1 , wherein the flame retardant component is in a pulverulent form with a median particle size of from 1 to 50 μm.  
     
     
         13 . The pulverulent composition as claimed in  claim 1 , wherein the flame retardant component is in a pulverulent and a coated form.  
     
     
         14 . The pulverulent composition as claimed in  claim 1 , further comprising a metal soap from 0.01 to 30% by weight based on the total amount of polyamides present in the powder.  
     
     
         15 . The pulverulent composition as claimed in  claim 14 , wherein the metal soap is present in an amount of from 0.5 to 15% by weight based on the total amount of polyamides present in the powder.  
     
     
         16 . The pulverulent composition as claimed in  claim 1 , further comprising fine metal soap particles mixed with polyamide particles.  
     
     
         17 . The pulverulent composition as claimed in  claim 1 , further comprising metal soaps incorporated within polyamide particles.  
     
     
         18 . The pulverulent composition as claimed in  claim 17 , wherein the metal soaps are alkali metal or alkaline earth metal salts of alkanemonocarboxylic acids or dimer acids.  
     
     
         19 . The pulverulent composition as claimed in  claim 17 , wherein the metal soaps are sodium or calcium salts of alkanimonocarboxylic acids or dimers acids.  
     
     
         20 . A process for preparing the pulverulent composition as claimed in  claim 1 , the process comprising: 
 mixing the at least one polymer with a flame retardant comprising ammonium polyphosphate.    
     
     
         21 . The process as claimed in  claim 20 , wherein the polymer powder is obtained by reprecipitation or milling, and is mixed in a dry blend process with the flame retardant comprising ammonium polyphosphate.  
     
     
         22 . The process as claimed in  claim 20 , wherein the flame retardant comprising ammonium polyphosphate is compounded into a melt of polymer, and the resultant mixture is processed by milling to produce a powder.  
     
     
         23 . A method for producing moldings by a layer-by-layer process which selectively bonds the powder, the method comprising: 
 adding the pulverulent composition of  claim 1  to a molding mixture.    
     
     
         24 . The method of  claim 23 , wherein the moldings are produced by selective laser sintering, selective inhibition of the bonding of powders, 3D printing, or a microwave process.  
     
     
         25 . A molding, produced by a process for the layer-by-layer build-up of three-dimensional objects by selectively bonding portions of a powder to one another, the molding comprising: 
 at least one flame retardant that comprises ammonium polyphosphate and at least one polymer.    
     
     
         26 . The molding as claimed in  claim 25 , comprising: 
 a polyamide which contains at least 8 carbon atoms per carboxamide group.    
     
     
         27 . The molding as claimed in  claim 25 , wherein the polymer is nylon-6,12, nylon-11, nylon-12, or a copolymer of these polyamides.  
     
     
         28 . The molding as claimed in  claim 25 , wherein the flame retardant is present in an amount of from 5 to 50% by weight, based on the total amount of components present, wherein the flame retardant comprises ammonium polyphosphate.  
     
     
         29 . The molding as claimed in  claim 25 , which, wherein the flame retardant is present in an amount of from 30 to 35% by weight, based on the total amount of the polymers present, and wherein the flame retardant comprises ammonium polyphosphate.  
     
     
         30 . The molding as claimed in  claim 25 , further comprising fillers and/or pigments.  
     
     
         31 . The molding as claimed in  claim 25 , further comprising a metal soap in an amount of from 0.01 to 30% by weight, based on the total amount of the polyamides present in the powder.  
     
     
         32 . The molding as claimed in  claim 25 , further comprising a metal soap in an amount of from 0.5 to 15% by weight, based on the total amount of the polyamides present in the powder.  
     
     
         33 . The molding as claimed in  claim 25 , further comprising fine metal soap particles mixed with polyamide particles.  
     
     
         34 . The molding as claimed in  claim 25 , wherein the powder comprises metal soaps incorporated within polyamide particles.  
     
     
         35 . The molding as claimed in  claim 34 , wherein the metal soaps are alkali metal or alkaline earth metal salts of alkanemonocarboxylic acids or dimer acids.  
     
     
         36 . The molding as claimed in  claim 34 , wherein the metal soaps are sodium or calcium salts of alkanemonocarboxylic acids or dimer acids.