Flame retardant polycarbonate composition
This invention is directed to an improved flame retardant polycarbonate composition of an aromatic carbonate polymer in admixture with an organic alkali metal salt or an organic alkaline earth metal salt or mixtures thereof, the improvement which comprises having an admixture with the polycarbonate a siloxane in sufficient quantity to render the polycarbonate composition non-dripping. 
     BACKGROUND OF THE INVENTION 
     In the art, there are many flame retardant additives which are employed by mixing with polycarbonate to render such materials self-extinguishing or flame retardant. Such flame retardant additives are employed in varying amounts in order to be effective in extinguishing burning of these products which are combustible. 
     However, even if the polycarbonate does not burn, in flame, it may drip hot particles which can ignite material below it. 
     DESCRIPTION OF THE INVENTION 
     It has been surprisingly discovered that an aromatic polycarbonate made flame retardant by incorporating with the aromatic polycarbonate organic alkali metal salts or organic alkaline earth metals salts or mixtures thereof can be rendered non-dripping by admixing the flame retardant polycarbonate with a silane or siloxane or mixtures thereof. 
     THE SILOXANES WHICH MAY BE EMPLOYED IN THE INSTANT INVENTION INCLUDE COMPOUNDS OF THE FORMULA: ##EQU1## wherein the R&#39;s are independently selected from the group consisting of hydrogen, hydroxy, alkyl of from 1 to 6 carbon atoms, alkoxy of from 1 to 6 carbon atoms, alkenyl from 2 to 8 carbon atoms; alkynyl from 2 to 10 carbon atoms, aryl from 6 to 18 carbon atoms, arylox from 6 to 10 carbon atoms. These may be optionally substituted by halogen, hydroxy, amino, alkoxy of 1 to 6 carbon atoms, aryloxy of 6 to 10 carbon atoms, alkylthio and alkylamino wherein the alkyl portion contains 1 to 6 carbon atoms, arylthio and arylamino wherein the aryl portion contains 6 to 10 carbon atoms and wherein n is an integer having a value of one or more. Examples of these compounds include octaphenylcyclotetrasiloxane; 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclo tetrasiloxane; α,ω-divinylpoly-(dimethysiloxane); 1,1,3,3-tetramethyl-1,3-divinylsiloxane; branched methyl phenyl silicone fluid; linear dimethyl siloxane (1000 centipoise viscosity); trimethylsilyl terminated methylhydrogensiloxy diphenylsiloxy copolymers; α ,ω-dimethylpoly (dimethylmethylvinylsiloxane); trimethylsilyl terminated polymethylhydrogen siloxane; octachlorooctaphenylcyclotetrasiloxane; diorganopolysiloxane gums having a viscosity of 80 million to 100 million centistokes; branched methyl trichlorophenyl silicone fluid; linear bis(pentafluorophenyl) siloxane branched methyl phenyl siloxane copolymer; etc., and mixtures thereof. These are prepared by known methods in the art, as for example, by the methods set forth in U.S. Pat. Nos. 2,445,794; 2,448,756; 2,484,595 and 3,514,424. 
     The amount of the siloxane to be used can be from about 0.01 to about 5.0 weight percent based on the total weight of the resin. 
     The composition of the instant invention may also include fibrous glass as described in copending application (A) of Charles A. Bialous, John B. Luce and Victor Mark, Ser. No. 496,127 filed concurrently herewith and assigned to the same assignee as the present invention. Also, the composition of the instant invention may include the fluorinated polyolefin described in copending application (B) of Charles A. Bialous, John B. Luce and Victor Mark, Ser. No. 496,128 filed concurrently herewith and assigned to the same assignee as the present invention. Applications A and B are incorporated herein by reference. Further, the instant composition can include both fibrous glass and fluorinated polyolefin. 
     The organic alkali metal and alkaline metal salts employed herein are fully described in the following applications: 
     Application (A) of Victor Mark and Thomas J. Hoogeboom, Ser. No. 429,643 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition, now U.S. Pat. No. 3,933,734, issued Jan. 20, 1976. 
     This application disclosed a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of either monomeric or polymeric aromatic sulfonic acids, or mixtures thereof. 
     Application (B) of Victor Mark, Ser. No. 429,121 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of either monomeric or polymeric aromatic sulfonesulfonic acids, or mixtures thereof. 
     Application (C) of Victor Mark, Ser. No. 429,642 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention, now U.S. Pat. No. 3,926,908, issued Dec. 16, 1975. This application discloses a flame retardant polycarbonate composition comprisng in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of sulfonic acids of aromatic ketones, or mixtures thereof. 
     Application (D) of Victor Mark, Ser. No. 429,166 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention, now U.S. Pat. No. 3,919,167, issued Nov. 11, 1975. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbontate polymer and a flame retardant additive which may be the metal salts of heterocyclic sulfonic acids, or mixtures thereof. 
     Application (E) of Victor Mark, Ser. No. 429,125 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the alkali metal salts of halogenated methanesulfonic acids or mixtures thereof, or mixtures of the alkali metal salts and the alkali earth metal salts. 
     Application (F) of Victor Mark, Ser. No. 429,644 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be metal salts of a halogenated non-aromatic carboxylic acid or mixtures thereof. 
     Application (G) of Victor Mark, Ser. No. 429,163 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention, now U.S. Pat. No. 3,909,490, issued Sept. 30, 1975. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of sulfonic acids of aromatic sulfides, or mixtures thereof. 
     Application (H) of Victor Mark, Ser. No. 429,128 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of either monomeric or polymeric aromatic ether sulfonic acids, or mixtures thereof. 
     Application (I) of Victor Mark, Ser. No. 429,645 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assigne as the present invention, now U.S. Pat. No. 3,931,100, issued Jan. 6, 1976. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of aliphatic and olefinic sulfonic acids, and mixtures thereof. 
     Application (J) of Victor Mark, Ser. No. 429,126 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of either monomeric or polymeric phenol ester sulfonic acids, or mixtures thereof. 
     Application (K) of Victor Mark, Ser. No. 429,164 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of unsubstituted or halogenated oxocarbon acids, or mixtures thereof. 
     Application (L) of Victor Mark, Ser. No. 429,127 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of sulfonic acids of monomeric and polymeric aromatic carboxylic acids and esters, and mixtures thereof. 
     Application (M) of Victor Mark, Ser. No. 429,165 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention, now U.S. Pat. No. 3,917,559, issued Nov. 4, 1975. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of halocycloaliphatic aromatic sulfonic acids. 
     Application (N) of Victor Mark, Ser. No. 429,646 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of either monomeric or polymeric aromatic amide sulfonic acids, or mixtures thereof. 
     Application (O) of Victor Mark, Ser. No. 429,120 filed Dec. 28, 1973 titled A Flame Retardant Polycarbonate Composition and assigned to the same assignee as the present invention. This application discloses a flame retardant polycarbonate composition comprising in admixture an aromatic carbonate polymer and a flame retardant additive which may be the metal salts of either monomeric or polymeric aromatic sulfonic acids, or mixtures thereof. 
     Applications A through O are incorporated herein by reference. The metal salts of any of these applications as well as mixtures of any of the metal salts of any of the applications may be used. 
     Preferred salts include sodium 2,4,5-trichlorobenzenesulfonate; sodium benzenesulfonate; disodium naphthalene-2,6-disulfonate; sodium p-iodobenzenesulfonate; sodium 4,4&#39;-dibromobiphenyl-3-sulfonate; sodium 2,3,4,5,6-pentachloro-betastyrenesulfonate; sodium 4,4&#39;-dichlorodiphenylsulfide-3-sulfonate; disodium tetrachlorodiphenyletherdisulfonate; disodium 4,4&#39;-dichlorobenzophenone-3,3&#39;-disulfonate; sodium 2,5-dichlorothiophene-3-sulfonate; sodium salt of diphenylsulfone-3-sulfonic acid; sodium dimethyl 2,4,6-trichloro-5-sulfoisophthalate; potassium salt of the sulfonic acid of dichlorophenyl 2,4,5-trichlorobenzene sulfonate; calcium salt of 2,4,5-trichlorobenzenesulfonanilide-4&#39;-sulfonate; sodium 4&#39;[1,4,5,6,7,7-hexachlorobicyclo-[2.2.1.]-hept-5-en-endo-2-yl] -benzenesulfonate; disodium hexafluoroglutarate; disodium chloranilate; and mixtures. These salts are used in amount of from 0.01 to about 10 weight percent based on the weight of the aromatic carbonate polymer composition. 
     The aromatic carbonate polymers employed in the practice of this invention are homopolymers and copolymers that are prepared by reacting a dihydric phenol with a carbonate precursor. The dihydric phenols that can be employed are bisphenols such as bis(4-hydroxyphenyl) methane, 2,2-bis(4-hydroxyphenyl) propane (hereinafter referred to as bisphenol-A), 2,2-bis(4-hydroxy-3-methylphenyl) propane, 4,4-bis(4-hydroxyphenyl) heptane, 2-2-bis(4-hydroxy-3,5-dichlorophenyl) propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl) propane, etc., dihydric phenol ethers such as bis(4-hydroxyphenyl) ether, bis(3,5-dichloro-4-hydroxyphenyl) ether, etc.; dihydroxydiphenyls such as p,p&#39;-dihydroxydiphenyl, 3,3&#39;dichloro-4,4&#39;-dihydroxydiphenyl, etc.; dihydroxyaryl sulfones such as bis(4-hydroxyphenyl) sulfone, bis(3,5-dimethyl-4-hydroxyphenyl) sulfone, etc., dihydroxy benzenes, resorcinol, hydroquinone, halo-and alkyl-substituted dihydroxy benzenes such as 1,4-dihydroxy-2, 5-dichlorobenzene, 1,4-dihydroxy-3-methylbenzene, etc., and dihydroxy diphenyl sulfoxides such as bis(4-hydroxyphenyl) sulfoxide, bis-(3,5-dibromo-4-hydroxyphenyl) sulfoxide, etc. A variety of additional dihydric phenols are also available to provide carbonate polymers and are disclosed in U.S. Pat. Nos. 2,999,835; 3,028,365 and 3,153,008. Also suitable for preparing the aromatic carbonate polymers are copolymers prepared from any of the above copolymerized with halogen-containing dihydric phenols such as 2,2-bis(3,5-dichloro-4-hydroxyphenyl) propane, 2,2-bis(3,5-dibromo-4-hydroxyphenyl) propane, etc. It is of course possible to employ two or more different dihydric phenols or a copolymer of a dihydric phenol with a glycol or with hydroxy or acid terminated polyester, or with a dibasic acid in the event a carbonate copolymer or interpolymer rather than a homopolymer is desired for use in the preparation of the aromatic carbonate polymers of this invention. Also employed in the practice of this invention may be blends of any of the above materials to provide the aromatic carbonate polymer. 
     The carbonate precursor may be either a carbonyl halide, a carbonate ester or a haloformate. The carbonyl halides which can be employed herein are carbonyl bromide, carbonyl chloride and mixtures thereof. Tpyical of the carbonate esters which may be employed herein are diphenyl carbonate, di-(halophenyl) carbonates such as di-(chlorophenyl) carbonate, di-(bromophenyl) carbonate, di-(trichlorophenyl) carbonate, di-(tribromophenyl) carbonate, etc., di-(alkylphenyl) carbonate such as di-(tolyl) carbonate, etc., di-(naphthyl) carbonate, di-(chloronaphthyl) carbonate, etc., or mixtures thereof. The haloformates suitable for use herein include bis-haloformates of dihydric phenols (bischloroformates of hydroquinone, etc.) or glycols (bishaloformates of ethylene glycol, neopentyl glycol, polyethylene glycol, etc.). While other carbonate precursors will occur to those skilled in the art, carbonyl chloride also known as phosgene is preferred. 
     Also included are the polymeric materials of a dihydric phenol, a dicarboxylic acid and carbonic acid. These are disclosed in U.S. Pat. No. 3,169,121 which is incorporated herein by reference. 
     The aromatic carbonate polymers of this invention are prepared by employing a molecular weight regulator, an acid acceptor and a catalyst. The molecular weight regulators which may be employed in carrying out the process of this invention include phenol, cyclohexanol, methanol, para-tertiarybutylphenol, parabromophenol, etc. Preferably, para-tertiarybutylphenol is employed as the molecular weight regulator. 
     A suitable acid acceptor may be either an organic or an inorganic acid acceptor. A suitable organic acid acceptor is a tertiary amine and includes such materials as pyridine, triethylamine, dimethylaniline, tributylamine, etc. The inorganic acid acceptor may be one which can be either a hydroxide, a carbonate, a bicarbonate, or a phosphate of an alkali or alkali earth metal. 
     Obviously other materials can be also be employed with the aromatic carbonate polymer of this invention and include such materials as anti-static agents, pigments, mold release agents, thermal stabilizers, ultraviolet stabilizers, reinforcing fillers and the like. 
     The composition of this invention is prepared by admixing the aromatic carbonate polymer with the organic alkali metal or alkaline earth metal salts and the siloxane. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The following examples are set forth to illustrate more clearly the principle and practice of this invention to those skilled in the art. Unless otherwise specified, where parts or percents are mentioned, they are parts or percents by weight. 
     EXAMPLE I 
     A polycarbonate composition is prepared by extruding a homopolymer of 2,2-bis(4-hydroxyphenyl) propane (hereinafter referred to as bisphenol-A) prepared by reacting essentially equimolar amounts of bisphenol-A and phosgene in an organic medium with triethylamine, sodium hydroxide, and phenol, under standard conditions. The resulting polymer is then fed to an extruder, which extruder is operated at about 265°C, and the extrudate is comminuted into pellets. 
     The pellets are then injection molded at about 315°C into test bars of about 5 inches by 1/2 inch by about 1/16-18 inch thick. The test bars (five for each additive listed in the Table) are subjected to the test procedure set forth in Underwriters&#39; Laboratories, Inc. Bulletin UL-94, Burning Test for Classifying Materials (hereinafter referred to as UL-94). In accordance with this test procedure, materials so investigated are rated either UL-94 V-0, UL-94 V-I, or UL-94 V-II based on the results of five specimens. The criteria for each V rating per UL-94 is briefly as follows: 
     &#34;UL-94 V-0&#34;: 
     Average flaming and/or glowing after removal of the igniting flame shall not exceed 5 seconds and none of the specimens shall drip particles which ignite absorbent cotton. 
     &#34;UL-94 V-I&#34;: 
     Average flaming and/or glowing after removal of the igniting flame shall not exceed 25 seconds and none of the specimens shall drip particles which ignite absorbent cotton. 
     &#34;UL-94V-II&#34;: 
     Average flaming and/or glowing after removal of the igniting flame shall not exceed 25 seconds and the specimens drip flaming particles which ignite absorbent cotton. 
     In addition, a test bar which continues to burn for more than 25 seconds after removal of the igniting flame is classified, not by UL-94 but by the standards of the instant invention, as &#34;burns.&#34; Further, UL-94 requires that all test bars must need the UL-94 type rating to achieve the particular rating. Otherwise, the five bars receive the rating of the worst single bar. For example, if one bar is classified as UL-94 V-II and the other four are classified as UL-94 V-O, then the rating for all five bars is UL-94 V-II. 
     The results are shown in the Table. 
     EXAMPLE II 
     To the polycarbonate of Example I is added 0.5 parts of sodium 2,4,5-trichlorobenzenesulfonate. The mixture is extruded, molded, and tested in the same manner as described in Example I. 
     EXAMPLE III 
     To the polycarbonate of Example I is added 0.5 parts of sodium 2,4,5-trichlorobenzenesulfonate and 0.05 parts of octaphenylcyclotetrasiloxane. The mixture is extruded, molded and tested in the same manner as described in Example I. 
     The remaining compositions are prepared by the methods of Examples I to III. 
     
                                           TABLE                                   
__________________________________________________________________________
                                      Flame Out Time                      
                                               No. of Drips               
Example                                                                   
      Salt Additive     Parts                                             
                             Siloxane                                     
                                  Parts                                   
                                      Seconds (Avg.)                      
                                               Per Five                   
                                                        Rating            
__________________________________________________________________________
I                                     13.4     10       Burning           
II    Sodium 2,4,5-trichlorobenzene                                       
                        0.5           3.4      8        UL-94 V-II        
      sulfonate                                                           
III   Sodium 2,4,5-trichlorobenzene                                       
                        0.5  A    1.0 2.6      0        UL-94 V-O         
      Sulfonate                                                           
IV    Sodium benzenesulfonate                                             
                        1.0  B    0.6 4.4      0        UL-94 V-O         
V     Disodium naphthalene-2,6-                                           
                        1.0  C    1.0 4.8      0        UL-94 V-O         
      disulfonate                                                         
VI    Disodium tetrachlorodiphenyl-                                       
                        0.5           4.4      2        UL-94 V-II        
      etherdisulfonate                                                    
VII   Disodium tetrachlorodiphenyl-                                       
                        0.5  C    0.8 3.6      0        UL-94 V-O         
      etherdisulfonate                                                    
VIII  Sodium 2,3,4,5,6-pentachloro-                                       
                        0.5  D    0.5 3.8      0        UL-94 V-O         
      beta-styrenesulfonate                                               
IX    Sodium 4,4&#39;-dichlorodiphenyl-                                       
                        0.5  B    0.6 3.8      0        UL-94 V-O         
      sulfide-3-sulfonate                                                 
X     Disodium 4,4&#39;-dichloro-                                             
                        0.5  B    0.5 4.5      0        UL-94 V-O         
      benzophenone-3,3&#39;-disulfonate                                       
XI    Sodium 2,5-dichlorothiophene-                                       
                        0.3  B    0.5 4.8      0        UL-94 V-O         
      3-sulfonate                                                         
XII   Sodium diphenylsulfone-3-                                           
                        0.4  B    0.8 3.4      0        UL-94 V-O         
      sulfonate                                                           
XIII  Sodium dimethyl 2,4,6-tri-                                          
                        1.0  C    0.2 3.8      0        UL-94 V-O         
      chloro-5-sulfoisophthalate                                          
XIV   Potassium Salt of the sulfonic                                      
                        0.3  B    0.5 4.8      0        UL-94 V-O         
      acid of dichlorophenyl 2,4,5-                                       
      trichlorobenzenesulfonate                                           
XV    Calcium 2,4,5-trichloro-                                            
                        1.0  B    0.6 3.9      0        UL-94 V-O         
      benzenesulfonamilide-4&#39;-                                            
      sulfonate                                                           
XVI   Sodium 4&#39;[1,4,5,6,6,7-                                              
                        1.0  A    2.0 4.4      0        UL-94 V-O         
      tetrachlorobicyclo-[2.2.1]-                                         
      hept-5-en-endo-2-yl]                                                
      benzenesulfonate                                                    
XVII  Disodium hexafluoroglutarate                                        
                        1.0  A    1.0 6.4      0        UL-94 V-I         
XVIII Disodium chloranilate                                               
                        0.2  D    3.0 4.8      0        UL-94             
__________________________________________________________________________
                                                        V-O               
 A Octaphenylcyclotetrasiloxane                                           
 B Branched methyl phenyl silicone                                        
 C Poly(methylhydrogensiloxane)                                           
 D Diorganopolysiloxane gum                                               
 
    
     As can be seen from the data in the Table, when the polycarbonate compositions contain the siloxanes in addition to the flame retardant additives, the polycarbonate does not drip and is rated UL-94 V-O. 
     Other flame retardant additives and siloxanes can be substituted for those of the Table with similar results. 
     It will thus be seen that the objects set forth above among those made apparent from the preceding description are efficiently attained and since certain changes may be made in carrying out the above process and in the composition set forth without departing from the scope of this invention, it is intended that all matters contained in the above description shall be interpreted as illustrative and not in a limiting sense.