Halogen-free fire retardant system for low heat release polymers

Abstract

An intumescent fire retardant system for making polymeric moldings that is halogen-free and provides fire shielding, thermal shielding and a low heat release rate. The intumescent fire retardant system of the present invention comprises, on the basis of 100 parts by weight blended mixture, 20-45 parts of a polymeric binder based on high density polyethylene and an α-olefin-containing copolymer, such as linear low density polyethylene, and 5-25 parts of a nitrogenous gas-generating agent, 10-30 parts of a water vapor-generating agent, 1-5 parts of an antioxidant, and 0-15 parts of a reinforcing agent. The fire retardant system of the present invention is essentially halogen-free.

1 . An intumescent fire retardant system for use in polymeric moldings, comprising, on the basis of 100 parts by weight blended mixture of a polymer component comprising: 
 20-45 parts of a polymeric binder comprising high density polyethylene having a density in the range of 0.940-0.970 g/cm 3  and an α-olefin-containing copolymer in the range of 0.870-0.910 g/cm 3 , wherein the system comprises 20-45 parts of the high density polyethylene and 0-15 parts of the α-olefin-containing copolymer for a total of 20-45 parts polymeric binder;    5-25 parts of a nitrogenous gas-generating agent selected from the group consisting of amines, ureas, guanidines, guanamines, s-triazines, amino acids, salts thereof, and mixtures thereof, wherein the salts are selected from the group consisting of phosphates, phosphonates, phosphinates, borates, cyanurates, sulfates and mixtures thereof;    10-35 parts of a water vapor-generating agent;    1-5 parts of an antioxidant; and    0-15 parts of a reinforcing agent, wherein the system is essentially halogen-free.    
   
   
       2 . The fire retardant system of  claim 1  wherein the α-olefin-containing copolymer is a copolymer of ethylene with one of butene, hexene and octene.  
   
   
       3 . The fire retardant system of  claim 1  wherein the α-olefin-containing copolymer is a linear low density ethylene octene copolymer.  
   
   
       4 . The fire retardant system of  claim 1  wherein nitrogenous gas-generating agent is an ammonium salt, a melamine salt, or a mixture thereof.  
   
   
       5 . The fire retardant system of  claim 1  wherein the nitrogenous gas-generating agent is selected from the group consisting of: melamine phosphates, melamine polyphosphates, melamine pyrophosphates, melamine cyanurates, ammonium phosphates, ammonium polyphosphates, ammonium pyrophosphates, ammonium cyanurates, and mixtures thereof.  
   
   
       6 . The fire retardant system of  claim 1  wherein the water vapor-generating agent is selected from the group consisting of: hydrated magnesia, hydrated alumina, intercalated graphite, and mixtures thereof.  
   
   
       7 . The fire retardant system of  claim 1  wherein the antioxidant is selected from the group consisting of: distearylthiodipropionate, a hindered phenol, and mixtures thereof.  
   
   
       8 . The fire retardant system of  claim 1  wherein the reinforcing agent is selected from the group consisting of: glass fibers, mica, titanium oxide and mixtures thereof.  
   
   
       9 . An intumescent fire retardant polymeric moldable composition comprising, on the basis of 100 parts by weight blended mixture: 
 55-80 parts of a polymeric matrix; and    20-45 parts of the intumescent fire retardant system of  claim 1 .    
   
   
       10 . The intumescent fire retardant polymeric composition of  claim 9  wherein the polymeric matrix is a thermoplastic polymer selected from the group consisting of: polypropylene, nylon, polystyrene, a styrene-acrylonitrile copolymer, and a butadiene-styrene-acrylonitrile terpolymer.  
   
   
       11 . The intumescent fire retardant polymeric composition of  claim 9  wherein the polymeric matrix is a thermoset polymer selected from the group consisting of a polyurethane and an epoxy.  
   
   
       12 . The intumescent fire retardant polymeric composition of  claim 9  wherein the polymeric matrix is a thermoplastic polymer selected from the group consisting of: injection molding grade high density polyethylene, blow molding grade high density polyethylene, and extrusion molding grade high density polyethylene.  
   
   
       13 . An intumescent fire retardant system for use in polymeric moldings, comprising, on the basis of 100 parts by weight blended mixture: 
 20-45 parts of a polymeric binder comprising high density polyethylene having a density in the range of 0.940-0.970 g/cm 3  and an α-olefin-containing copolymer having a density in the range of 0.870-0.910 g/cm 3 , wherein 20-45 parts of the blended mixture is the high density polyethylene and 0-15 parts of the blended mixture is the α-olefin-containing copolymer;    15-25 parts of a nitrogenous gas-generating agent selected from the group consisting of an ammonium salt, a melamine salt, or mixtures thereof, wherein the salts are selected from the group consisting of phosphates, phosphonates, phosphinates, borates, cyanurates, sulfates and mixtures thereof;    20-30 parts of a water vapor-generating agent selected from the group consisting of hydrated magnesia, hydrated alumina, intercalated graphite, and mixtures thereof;    1-5 parts of an antioxidant selected from the group consisting of distearylthiodipropionate, a hindered phenol, and mixtures thereof; and    3-10 parts of a reinforcing agent selected from the group consisting of glass fibers, mica, titanium oxide and mixtures thereof, wherein the system is essentially halogen-free.    
   
   
       14 . The fire retardant system of  claim 13  wherein the α-olefin-containing copolymer is a copolymer of ethylene with one of butene, hexene and octene.  
   
   
       15 . The fire retardant system of  claim 13  wherein the α-olefin-containing copolymer is a linear low density ethylene octene copolymer.  
   
   
       16 . The intumescent fire retardant polymeric composition of  claim 13  wherein the polymeric matrix is a thermoplastic polymer selected from the group consisting of: polypropylene, nylon, polystyrene, a styrene-acrylonitrile copolymer, and a butadiene-styrene-acrylonitrile terpolymer.  
   
   
       17 . The intumescent fire retardant polymeric composition of  claim 13  wherein the polymeric matrix is a thermoset polymer selected from the group consisting of a polyurethane and an epoxy.  
   
   
       18 . The intumescent fire retardant polymeric composition of  claim 13  wherein the polymeric matrix is a thermoplastic polymer selected from the group consisting of: injection molding grade high density polyethylene, blow molding grade high density polyethylene, and extrusion molding grade high density polyethylene.  
   
   
       19 . An intumescent fire retardant thermoplastic moldable composition comprising, on the basis of 100 parts by weight blended mixture: 
 55-80 parts of a thermoplastic matrix; and    20-45 parts of an intumescent fire retardant additive comprising on the basis of  100  parts by weight blended mixture: 20-45 parts of a polymeric binder comprising high density polyethylene having a density in the range of 0.940-0.970 g/cm 3  and an α-olefin-containing copolymer having a density less than the density of the high density polyethylene;    5-25 parts of a nitrogenous gas-generating agent selected from the group consisting of amines, ureas, guanidines, guanamines, s-triazines, amino acids, salts thereof, and mixtures thereof, wherein the salts are selected from the group consisting of phosphates, phosphonates, phosphinates, borates, cyanurates, sulfates, and mixtures thereof;    10-35 parts of a water vapor-generating agent;    1-5 parts of an antioxidant; and    0-15 parts of a reinforcing agent, wherein the thermoplastic polymer matrix and the intumescent fire retardant additive are each essentially halogen-free, and wherein the composition exhibits a peak heat release rate of less than 500 kW/m 2  as measured by the ASTM E1354 cone calorimeter method.