Flame-retardant expandable polymers

Abstract

The invention relates to flame-retardant expandable polymers and to polymer foams and to the use thereof. According to the invention, at least one of the following phosphorus compounds is used as a flame retardant: phosphorus compound according to formula (Ia): (Ia) 10-hydroxy-9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-OH); or the salts thereof according to formula (Ib): (Ib) (DOPO-OR); or the ring-opened hydrolysates thereof according to formula (Ic): (Ic).

1 . Flame-retardant expandable polymerizates containing at least one propellant, characterized in that at least one of the following phosphorus compounds is contained as a flame retardant:
 phosphorus compound according to formula (Ia):   
       
         
           
           
               
               
           
         
       
       10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO-OH)
 or salts thereof according to formula (Ib): 
 
       
         
           
           
               
               
           
         
         or ring-opened hydrolyzates thereof according to formula (Ic): 
       
       
         
           
           
               
               
           
         
       
     
     
         2 . The expandable polymerizates according to  claim 1 , characterized in that residue R +  is an organic or inorganic cation. 
     
     
         3 . The expandable polymerizates according to  claim 1 , characterized in that residue R +  is a salt of a quaternary ammonium compound NR 4   +  or a quaternary phosphonium compound PR 4   + . 
     
     
         4 . The expandable polymerizates according to  claim 1 , characterized in that residue R +  in general formula (Ib) or (Ic) is NH 4   +  and the phosphorus compound is 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide ammonium salt: 
       
         
           
           
               
               
           
         
       
     
     
         5 . The expandable polymerizates according to  claim 1 , characterized in that residue R +  in general formula (Ib) or (Ic) is guanidinium and the phosphorus compound is 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide guanidinium salt: 
       
         
           
           
               
               
           
         
       
     
     
         6 . The expandable polymerizates according to  claim 1 , characterized in that residue R +  in general formula (Ib) or (Ic) is melaminium and the phosphorus compound is 10-hydroxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide melaminium salt: 
       
         
           
           
               
               
           
         
       
     
     
         7 . The expandable polymerizates according to  claim 1 , characterized in that the phosphorus compound(s) is/are contained at an amount of 0.5 to 25% by weight, particularly 1 to 15% by weight, based on the total weight of the polymer. 
     
     
         8 . The expandable polymerizates according to  claim 1 , characterized in that the expandable polymerizates are expandable styrene polymerizates (EPS) and/or expandable styrene polymer granulates (EPS), particularly consisting of homo- and copolymers of styrene, preferably crystal-clear polystyrene (GPPS), high-impact polystyrene (HIPS), anionically polymerized polystyrene or high-impact polystyrene (A-IPS), styrene-alpha-methylstyrene copolymers, acrylonitrile-butadiene-styrene polymerizates (ABS), styrene-acrylonitrile (SAN), acrylonitrile-styrene-acrylic ester (ASA), methylacrylate-butadiene-styrene (MBS), methylmethacrylate-acrylonitrile-butadiene-styrene (MABS) polymerizates, or mixtures thereof or mixtures with poly(phenylene ether) (PPE), and/or in that the expandable polymerizates consist of cellulose acetate butyrate (CAB) or contain cellulose acetate butyrate (CAB), and/or in that the expandable polymerizates consist of poly(lactic acid) (PLA) or contain poly(lactic acid) (PLA). 
     
     
         9 . The expandable polymerizates according to  claim 8 , characterized in that the expandable polymerizates are mixtures of the styrene polymerizates with expandable thermoplastic polymers such as cellulose acetate butyrate (CAB), thermoplastic polyurethane (TPU), poly(lactic acid), etc., wherein the thermoplastic polymers are contained at 1 to 99% by weight, based on the total polymer weight. 
     
     
         10 . The expandable polymerizates according to  claim 1 , characterized in that, additionally, sulfur and/or at least one sulfur-containing compound and/or sulfur compound is contained as a flame-retardant synergist. 
     
     
         11 . The expandable polymerizates according to  claim 1 , characterized in that sulfur and/or the at least one sulfur-containing compound and/or sulfur compound are/is contained at an amount of 1 to 25% by weight, particularly 2 to 15% by weight, based on the total weight of the polymer. 
     
     
         12 . The expandable polymerizates according to  claim 1 , characterized in that the sulfur-containing compound and/or sulfur compound have/has at least one S—S bond, wherein at least one of said sulfur atoms is present in the bivalent form, e.g. ammonium thiosulfate. 
     
     
         13 . The expandable polymerizates according to  claim 1 , characterized in that the sulfur-containing compounds and/or sulfur compounds exhibit a weight loss of less than 10% by weight in an analysis using thermogravimetry below 115° C. 
     
     
         14 . The expandable polymerizates according to  claim 1 , characterized in that the flame-retardant synergist is melaminium thiosulfate and/or bis[(2,4,6-tri-amino-1,3,5-triazinium)thio sulfate: 
       
         
           
           
               
               
           
         
       
     
     
         15 . The expandable polymerizates according to  claim 1 , characterized in that the flame-retardant synergist is para-tertiobutylphenol disulfide polymer: 
       
         
           
           
               
               
           
         
       
     
     
         16 . A method of preparing flame-retardant, expandable polymerizates according to  claim 1 , characterized in that at least one phosphorus compound of the general formulae (Ia), (Ib) or (Ic) is used as a flame retardant and optionally, sulfur and/or at least one sulfur-containing compound and/or sulfur compound are/is used as (an) additional flame retardant(s) and/or flame-retardant synergist(s). 
     
     
         17 . The method of preparing flame-retardant expandable polymerizates, particularly styrene polymerizates (EPS), according to  claim 16 ,
 wherein the flame retardant, melaminium thiosulfate, and a propellant are mixed with a polymer melt, particularly a styrene polymer melt, using a dynamic and/or static mixer and then granulated, or   wherein the flame retardant and melaminium thiosulfate are admixed to still granulated polymerizate, in particular polystyrene polymerizate, using a dynamic and/ or static mixer, and fused, and the melt is then treated with propellant and granulated, or   wherein the flame retardant and melaminium thiosulfate are admixed to still granulated polymerizate, particularly polystyrene polymerizate, using a mixer, and the mixture is then fused and granulated, or   wherein the granulate preparation is by suspension polymerization, particularly of styrene, in aqueous suspension in the presence of the flame retardant, melaminium thiosulfate and a propellant.   
     
     
         18 . The method of preparing flame-retardant expandable styrene polymerizates (EPS) according to  claim 16 , comprising the following steps:
 co-dosing into an extruder: PS or EPS granulate having a molecular weight of Mw>120,000 g/mol, preferably 150,000 to 250,000 g/mol, particularly preferably 180,000 to 220,000 g/mol, as well as the flame retardant, the flame-retardant synergist and optionally one or more additional additives, in particular:
 a) additional flame-retardant synergists such as thermal radical formers, e.g. dicumyl peroxide, at a concentration of 0.1 to 20% by weight, 
 b) infra-red opacifiers, e.g. graphite, carbon black, aluminum, titanium oxide, at a concentration of 0.1 to 1% by weight, 
 c) stabilizers, e.g. nitroxyl radical formers such as HTEMPO (4-hydroxy-2,2,6,6-tetramethyl piperidine-1-oxyl), at a concentration of 0.1 to 1% by weight, 
 d) other halogenated or halogen-free flame retardants, e.g. HBCD, DOP-O, magnesium hydroxide, at a concentration of 0.1 to 20% by weight, and/or 
 e) fillers, e.g. chalk, talc, silicates, in a concentration of 1 to 20% by weight; 
   melting all components together inside the extruder;   optionally admixing at least one propellant;   mixing all components at a temperature of >120° C.;   granulating by pressurized underwater granulation at, for example, 1-20 bar, to an granulate size of <5 mm, preferably 0.2 to 2.5 mm, at a water temperature of 30 to 100° C., particularly of 50 to 80° C.;   optionally coating the surface with coating agents such as silicates, metal salts of fatty acids, fatty acid esters, fatty acid amides.   
     
     
         19 . Flame-retardant expandable polymerizates, particularly styrene polymerizates (EPS), obtainable by the method of  claim 16 . 
     
     
         20 . A polymeric foam, particularly styrene polymer particle foam or extruded polystyrene rigid foam (XPS), containing at least one phosphorus compound of the general formulae (Ia), (Ib) or (Ic) according to  claim 1  as a flame retardant and optionally sulfur and/or at least one sulfur-containing compound or sulfur compound as (an) additional flame retardant(s) or flame-retardant synergist(s). 
     
     
         21 . The polymeric foam according to  claim 20 , obtainable from the flame-retardant expandable polymerizates, particularly from expandable styrene polymers (EPS), particularly by foaming and caking said polymerizates or by extrusion. 
     
     
         22 . The polymeric foam according to  claim 20  having a density of between 7 and 200 kg/m 3  and/or a predominantly closed-cell structure with more than 0.5 cells per mm 3 , particularly with a structure wherein more than 80% of the cells are closed cells. 
     
     
         23 . A use of at least one phosphorus compound of formula (Ia) and/or salts thereof of formula (Ib) and/or ring-opened hydrolyzates thereof of formular (Ic) according to  claim 1 , as (a) flame retardant(s) as well as optionally of sulfur and/or at least one sulfur-containing compound or sulfur compound as (a) flame-retardant synergist(s),
 in expandable polymerizates, particularly in expandable styrene polymers (EPS) and/or expandable styrene polymer granulates (EPS), or   in polymeric foams, particularly in styrene polymer particle foams, obtainable by foaming from expandable polymerizates, or in extruded polystyrene rigid foams (XPS).