Abstract:
Composition of an antimicrobial agent and an antioxidant having improved antimicrobial activity compared to the antimicrobial agent alone. The preferred environment of the invention is a composition of a thermoplastic resin, an antioxidant, and an antimicrobial agent, the latter two being compatible with the resin. The resin composition can contain other usual additives, and can be melt processed at an elevated temperature to form articles such as films or fibers having improved antimicrobial activity. A method for improving the efficacy of an antimicrobial agent by combining it with an antioxidant is disclosed. A method for melt-processing a resin composition containing an antimicrobial material is also disclosed, wherein the resin composition includes an antioxidant. The inventors have thus discovered and solved the problem of oxidation of an antimicrobial composition, particularly a resin composition containing an antimicrobial agent, which arises when the composition is processed at elevated temperatures, as are typically encountered when forming a fiber or film of the composition.

Description:
This is a divisional of co-pending application Ser. No. 897,487 filed on Sept. 22, 1986now abandoned, which is, in turn, a divisional of application Ser. No. 688,490 filed Jan. 3, 1985, now U.S. Pat. No. 4,624,679. 
    
    
     TECHNICAL FIELD 
     The present invention relates to thermoplastic articles and compositions containing antimicrobial agents and to novel stabilizers for antimicrobial agents. 
     BACKGROUND ART 
     It is well known that antimicrobial agents can be incorporated into thermoplastic materials during fabrication so the resulting thermoplastic articles will resist microbial growth. Thermoplastic compounds which are candidates for treatment include materials such as polyamides (nylon 6 or 6,6), polyvinyl chloride (with or without plasticizing agents), polyolefins, polyurethanes, polyethylene terephthalate (polyester), styrene-butadiene rubbers, other elastomers, etc. Antimicrobial agents which are candidates for incorporation into such thermoplastic materials include, but are not limited to, phenoxarsines (including bisphenoxarsines), phenarsazines (including bisphenarsazines), maleimides, isoindole dicarboximides having a sulfur atom bonded to the nitrogen atom of the dicarboximide group, halogenated aryl alkanols, isothiazolinone compounds, and organotin compounds. Others have also been used. 
     The known microbiocidal phenoxarsine and phenarsazine compounds include compounds represented by the formulas: ##STR1## where X is halogen or thiocyanate, Y is oxygen or sulfur, Z is oxygen or NH, R 1  is halogen, lower alkyl (having from 1 to about 6 carbon atoms), or thiocyanate, and n is from 1 to 4 inclusive. Examples of these phenoxarsines and phenarsazines include but are not limited to: 
     10-chlorophenoxarsine; 
     10-iodophenoxarsine; 
     10-bromophenoxarsine; 
     4-methyl-10-chlorophenoxarsine; 
     2-tert-butyl-10-chlorophenoxarsine; 
     1,4-dimethyl-10-chlorophenoxarsine 
     2-methyl-8, 10-dichlorophenoxarsine; 
     1,3,10-trichlorophenoxarsine; 
     2,6,10-trichlorophenoxarsine; 
     2,8,10-trichlorophenoxarsine; 
     1,2,4,10-tetrachlorophenoxarsine; 
     1, 2, 4, 10-thiocyanatophenoxarsine; 
     10-thiocyanatophenoxarsine; 
     10,10&#39;-thiobisphenoxarsine; 
     10,10&#39;-oxybisphenarsazine; 
     10,10-&#39;thiobisphenarsazine; and 
     10, 10&#39;-oxybisphenoxarsine (OBPA). 
     Many of these materials are described in U.S. Pat. No. 3,288,674, issued to Yeager Nov. 19, 1966. 
     The microbiocidal maleimide compounds are exemplified by N-(2-methylnaphthyl) maleimide. 
     The microbiocidal isoindole dicarboximides having a sulfur atom bonded to the nitrogen atom of the dicarboximide group contain at least one group having the structure: ##STR2## wherein the hexagonal ring can have one to three sites of ring saturation. 
     Particular isoindole dicarboximides are the following: ##STR3## 
     An example of a isothiazolinone compound which has been found useful is 2-(n-octyl-4-isothiazolin-3-one). 
     Other known antimicrobial agents are: bis(tri-n-butyl tin) oxide (TBTO); pentachlorophenol and its salts; zinc Omadine (a zinc derivative of pyridinethione sold by Olin Chemicals, Stamford, Conn.); 2&#39;-hydroxy-2, 4, 4&#39;-trichlorodiphenylether (Irgasan DP-300, sold by Ciba-Geigy Corporation, Plastics and Additives Division, Hawthorne, N.Y.); 2, 4, 5, 6-tetrachloroisophthalonitrile (Daconil 2787, sold by Diamond Alkali Company, Cleveland, Ohio); and 2-(4-thiazolyl)benzimidazole (trade name Tektamer 100, sold by the Calgon Division of Merck &amp; Co., Inc., Rahway, N.J.). 
     In all of these combinations of an antimicrobial agent and a thermoplastic material, the antimicrobial agent must: (1) have sufficient heat stability to avoid being destroyed or losing potency during fabrication; (2) not react with the thermoplastic resin nor any of its additives at elevated processing temperatures and other conditions; and (3) not become volatilized. In addition, the antimicrobial control agent should not impart undesirable features (odor, embrittlement) to the resin at use concentrations. A final requirement is that the composition effectively control microbial growth throughout the intended life of the finished article. 
     Synthetic fiber manufacture subjects the fiber composition to extremely rigorous conditions. For example, the fiber composition is melted and held at an elevated temperature prior to spinning. When spun, the composition is subjected to extremely high pressures and is further heated by the friction of extrusion. The extruded filaments are then cooled by ventilating them with air. The filaments have a large surface to volume ratio, and thus the composition is extensively exposed to atmospheric oxygen while cooling. 
     U.S. Pat. No. 3,345,341 claims thermoplastic compositions formed by blending an antimicrobial agent at a suitable ratio with chips of the polymer form prior to fabrication. The compositions are then spun into fibers. The degradation problem and possible solutions are not discussed. 
     U.S. Pat. No. 2,919,200 (Dubic, et al.) teaches incorporating a bacteriostatic agent in a thermoplastic composition, but simply specifies that the bacteriostatic agent should have a decomposition temperature above the molding temperature of the plastic. Many existing antimicrobial agents do not meet this criterion. 
     Similarly, U.S. Pat. No. 3,959,556 (Morrison) describes the preparation of synthetic fibers which incorporate an antimicrobial agent, and claims antimicrobial properties are possessed by blends of the treated synthetic fiber with naturally occurring fibers. 
     U.S. Pat. No. 3,279,986 (Hyman) describes preparation of a thermoplastic sheet material incorporating an antimicrobial agent. The specific antimicrobial agents claimed also are claimed to improve the thermal susceptibility of the sheet material. (&#34;Thermal susceptibility&#34; refers to the well known off-color that results from heating polyvinyl chloride resin materials.) 
     A weakness of all these patents is their failure to disclose that the antimicrobial agent present in the finished material often lacks some or all of its potency as a result of degradation during processing. 
     For example, if 500 parts per million (ppm) of OBPA is blended into a nylon composition, which is formed into fiber using conventional melt-spinning technology, only about 100 ppm of active OBPA will be present in the fiber. 
     This degradation has two important disadvantages. First, much of the antimicrobial agent is wasted so more of the agent must be incorporated in the chosen composition to provide a desired level of performance. Second, the decomposition products of the antimicrobial agent may be more easily released from a thermoplastic composition than the active agent. For example, when nylon fibers containing OBPA are vat dyed, much of the decomposition product (phenoxyarsenic acid) formed as a result of fiber fabrication migrates into the dye bath, necessitating removal before the dye effluent is released into the environment. If the amount of decomposition of OBPA during fiber formulation were reduced, the leaching of the phenoxyarsenic acid from fibers would be reduced. 
     Further, some known biological agents are not selected in these patents because the omitted agents are known to be insufficiently resistant to thermal inactivation. 
     The literature discloses using antioxidants in polymeric plastic compositions. There is a wide spectrum of needs for such antioxidants in different polymers and plastic compounds. For example, some resin compositions cannot be fabricated at all without antioxidants, while polyvinyl chloride compositions and polyamide (such as nylon) compositions do not benefit substantially from inclusion of an antioxidant except during high-temperature fabrication. 
     The following materials are known to act as antioxidants for plastic compositions: 
     
         ______________________________________MONOPHENOLS______________________________________1.  2,6-Di-t-butyl-p-cresol or    2,6-Di-t-butyl-4-methylphenol##STR4##    Mole Weight 220    White powder, flakes, granules or pellets    Melt Point 69-70° C.    Specific Gravity 1.04-1.05______________________________________TRADE NAME        SUPPLIER______________________________________BHT               KoppersCAO-1             Sherwin-WilliamsCAO-3             Sherwin-WilliamsDBPC              KoppersDBPC-80 (1)       KoppersIonol             ShellIonol CP          ShellLowinox BHT       LowiNaugard BHT       UniroyalPermanax BHT      VulnaxSustane BHT       UOPSustane 1-F       UOPVanox PC          VanderbiltVanox PC-X        VanderbiltVulkanox KB       Mobay______________________________________ (1) 80% 
    
     
         2.  Styrenated phenol##STR5##    Viscous straw colored liquid    Specific Gravity 1.08General purpose non-staining antioxidant used in rubber and______________________________________latexTRADE NAME           SUPPLIER______________________________________WINGSTAY S           GOODYEARWINGSTAY S Powder (1)                GOODYEARAntioxidant SP (2)   HarwickLowinox P24S         LowiNaugard SP           UniroyalNaugard SP Powder (3)                UniroyalNevastain 21         NevilleNevastain 2170 (3)   NevillePermanax SP (4)      VulnaxPermanax SP(L)       VulnaxStabilite SP 49-464 (5)                ReichholdStyrenated Phenol    Ferro/ProductolVanox 102            VanderbiltVanox 1002           Vanderbilt______________________________________ (1) 65% Active on inert carrier (2) Active concentration not listed  Specific Gravity 1.56 (3) 70% Active on inert carrier  Specific Gravity 1.32 (4) 60% Active on inert carrier (5) Listed as `polymeric styrenated 
    
     
         3.henol`-    2- and 3-t-Butyl-4-hydroxyanisole or    2- and 3-t-Butyl-4-methoxyphenol##STR6##    Mole Weight 180    White or off-white tablets or pellets    Melt Point 48-57° C.    Specific Gravity 1.04General purpose antioxidant frequently used in foods______________________________________TRADE NAME          SUPPLIER______________________________________Sustane BHA         UOPTenox BHA           Eastman______________________________________4.  Alkylated hindered phenols##STR7##    Viscous liquids varying in    color from pale straw to brownR&#39;s may be methyl or other alkyl groups, the larger ones usuallybeing tertiary. Frequently more than one type of group is present.General purpose antioxidants and polymer stabilizers for rubberand plastics. These generally have good color and stain______________________________________properties                          SPECIFICTRADE NAME        SUPPLIER     GRAVITY______________________________________WINGSTAY C        GOODYEAR     1.01WINGSTAY T        GOODYEAR     0.91WINGSTAY V        GOODYEAR     1.02Antioxidant 431   Uniroyal     1.08CAO-42            Sherwin-Williams                          0.93Cyanox LF         Cyanamid     1.06Cyanox 251 (1)    Cyanamid     1.39Cyanox 1735       Cyanamid     0.90Ethyl Antioxidant 733             Ethyl        0.94Ethyl Antioxidant 735             Ethyl        0.95Hydrochem A0-535C Continental  0.90             ProductsLowinox P24A      LowiNaugard 431       Uniroyal     1.08Permanax WSL      Vulnax       1.00Permanax WSL Powder             Vulnax       1.26Prodox 246        Ferro/Productol                          0.931Prodox 340        Ferro/Productol                          0.958Prodox 345        Ferro/Productol                          0.959Stabilite White Powder             Reichhold    1.3249-454Stabilite White Liquid 49-455             Reichhold    0.91Stabilite 49-470 (2)             ReichholdStabiwhite Powder C P Hall     1.32Uvinox 1494       GAF          0.90Vanox 100         Vanderbilt   1.03Vanox 100 Powder  Vanderbilt   1.37Vulkanox DS/F (3) Mobay        1.3______________________________________ (1) Cream white powder  contains an inert carrier (2) White powder (3) Contains 50% inorganic filler 
    
     
         5.  4-(Hydroxymethyl)-2,6-di-t-butylphenol##STR8##    Mole Weight 236.4    Off-white crystalline powder    Melt Point 138° C.______________________________________TRADE NAME           SUPPLIER______________________________________Ethyl Antioxidant 754                Ethyl______________________________________6.  `Fortified` hindered phenol    (Structure not disclosed)    White powder    Melt Point 95° C. min.    Specific Gravity 1.30General purpose phenolic antioxidant used in compounding wherecolor and staining are critical.______________________________________TRADE NAME           SUPPLIER______________________________________Vanox ZS             Vanderbilt______________________________________7.  2,6-Di-t-butyl-4-sec-butylphenol##STR9##    Mole Weight 262    Amber liquid    Specific Gravity 0.90______________________________________TRADE NAME           SUPPLIER______________________________________Isonox 132           SchenectadyVanox 1320           Vanderbilt______________________________________ 
    
     
         ______________________________________BISPHENOLS ANDTHIOBISPHENOLS______________________________________1.  2,2&#39;-Methylenebis(6-t-butyl-p-cresol) or    2,2&#39;-Methylenebis(4-methyl-6-t-butylphenol)##STR10##    Mole Weight 341    White or light colored powder    Melt Point 133° C.    Specific Gravity 1.04-1.08Antioxidant for rubber compounding. Some use in latex andplastics. Essentially non-staining, but can cause slight pinkdiscoloration.______________________________________TRADE NAME         SUPPLIER______________________________________Antioxidant MBP-5  AcetoCAO-5              Sherwin-WilliamsCAO-14             Sherwin-WilliamsCyanox 2246        CyanamidLowinox 22M46      LowiOxy-Chek 114       FerroSantowhite PC      MonsantoVanox 2246         VanderbiltVulkanox BKF       Mobay______________________________________2.  2,2&#39;-Methylenebis(4-ethyl-6-t-butylphenol)##STR11##    Mole Weight 369    White to cream powder    Melt Point 199-125° C.    Specific Gravity 1.10General purpose antioxidant weaker than (B-1), but lessdiscoloring.______________________________________TRADE NAME          SUPPLIER______________________________________Cyanox 425          Cyanamid______________________________________3.  4,4&#39;-Methylenebis(2,6-di-t-butylphenol)##STR12##    Mole Weight 424    Light yellow crystalline powder    Melt Point 154-155° C.    Specific Gravity 1.01General purpose antioxidant-stabilizer. Also used in resins.______________________________________TRADE NAME           SUPPLIER______________________________________Antioxidant MO14     AcetoEthyl Antioxidant 702                EthylEthyl Antioxidant 728 (1)                EthylLowinox 002          LowiProdox B-113         Ferro/Productol______________________________________ (1) `Soluble form2 
    
     
         4.  Miscellaneous bisphenols - structures not revealed______________________________________                    SPECIFIC  SUP-TRADE NAME   PHYS FORM   GRAVITY   PLIER______________________________________Cyanox 53 (1)        White powder                    1.74      CyanamidNaugawhite   Amber liquid                    0.96      UniroyalNaugawhite   Tan powder  1.19      UniroyalPowder (1)Permanax WSO White powder 1.00                    VulnaxWytox PAP    Amber liquid                    0.92      OlinWytox PAP-S (1)        Tan powder            OlinWytox        Amber liquid                    0.92      OlinPAP-SE (2)______________________________________ (1) `On an inert carrier`- (2) Self emulsifiable form5.  2,2&#39;-Ethylidenebis(4,6-di-t-butylphenol)##STR13##    Mole Weight 438    White powder    Melt Point 161-164° C.    Specific Gravity 1.01Antioxidant for rubber and plastics compounding.______________________________________TRADE NAME          SUPPLIER______________________________________Isonox 129          SchenectadyVanox 1290          Vanderbilt______________________________________6.  2,2&#39;-Methylenebis(4-methyl-6-(1-methylcyclohexyl)phenol##STR14##    Mole Weight 422    Off-white powder    Melt Point 120-130° C.    Specific Gravity 1.17Antioxidant for rubber and plastics compounding.______________________________________TRADE NAME           SUPPLIER______________________________________Nonox WSP            ICIPermanax WSP         VulnaxPermanax WSP (PQ)    Vulnax______________________________________7.  4,4&#39;-Butylidinebis(6-t-butyl-m-cresol) or    4,4&#39;-Butylidenebis(6-t-butyl-3-methylphenol)##STR15##    Mole Weight 382.5    White powder    Melt Point 209° C.    Specific Gravity 1.03______________________________________TRADE NAME          SUPPLIER______________________________________Lowinox 44B25       LowiSantowhite Powder   Monsanto______________________________________8.  Polybutylated Bisphenol A    Amber liquid    Specific Gravity 0.945-0.965Antioxidant for rubber compounding and raw polymerstabilization.______________________________________TRADE NAME            SUPPLIER______________________________________Agerite Superlite     VanderbiltAgerite Superlite Solid (1)                 VanderbiltLowinox P22B          LowiVanox 1003            VanderbiltVanox 1004 (Powder) (1)                 Vanderbilt______________________________________ (1) 75% Agerite Superlite or Vanox 1003 and 25% inert carrier Specific Gravity 1.26 
    
     
         9.  4,4&#39;-Thiobis(6-t-butyl-m-cresol) or    4,4&#39;- Thiobis(6-t-butyl-3-methylphenol)##STR16##    Mole Weight 358.5    Light colored powder    Melt Point 150° C.    Specific Gravity 1.06-1.12Antioxidant for rubber, latex and plastics compounding. Widelyused in CR. Activates CR cure systems.______________________________________TRADE NAME           SUPPLIER______________________________________Antioxidant TBM6 (1) AcetoLowinox 44S36        LowiSantonox (2)         MonsantoSantowhite Crystals  MonsantoSantowhite MK (3)    Monsanto______________________________________ (1) Technical and pure grades available (2) More pure form of Santowhite Crystals (3) Reaction product grade 
    
     
         10. 4,4&#39;-Methylenebis(2,6- dimethylphenol)##STR17##    Mole Weight 256______________________________________TRADE NAME         SUPPLIER______________________________________Lowinox 44M26      Lowi______________________________________11. 1,1&#39; -Thiobis(2-naphthol)##STR18##    Mole Weight 318    Light yellow powder    Melt Point 218° C. Min.______________________________________TRADE NAME          SUPPLIER______________________________________SAO-30              Southland______________________________________12. Methylene bridged polyalkylphenol    Solid    Specific Gravity 1.02______________________________________TRADE NAME           SUPPLIER______________________________________Ethyl Antioxidant 738                Ethyl______________________________________13. 2,2&#39;-Thiobis(4-methyl-6-t-butylphenol)##STR19##    Mole Weight 359______________________________________TRADE                   MELTNAME     PHYS FORM      POINT     SUPPLIER______________________________________SAO-4    Light yellow powder                   70° C. Min.                             SouthlandSAO-6    White powder   83-86° C.                             Southland______________________________________14. Sulfur containing hindered phenol cyanurate    White powder    Melt Point 190-195° C.______________________________________TRADE NAME          SUPPLIER______________________________________SAO-44              Southland______________________________________ 15.    2.2&#39;-Isobutylidenebis(4,6-dimethylphenol)##STR20##    Mole Weight 298    White powder    Specific Gravity 1.12______________________________________TRADE NAME          SUPPLIER______________________________________Lowinox 22IB46      LowiVulkanox NKF        Mobay______________________________________16. 2,2&#39;-Methylenebis(4-methyl-6-cyclohexylphenol)##STR21##    Mole Weight 393    Melt Point 125° C. Min.    Specific Gravity 1.08______________________________________TRADE NAME          SUPPLIER______________________________________Vulkanox ZKF        Mobay______________________________________ 
    
     
         __________________________________________________________________________POLYPHENOLS__________________________________________________________________________  Butylated reaction product of p-cresol and dicyclopentadiene   ##STR22##  Average Mole Weight 600-700  White powder or amber flake  Melt Point 100° C.  Specific Gravity 1.10Non-staining antioxidant for general and high temperature applications.Especiallyrecommended for NR,IR,SBR,CR and carboxylated polymers. Widely used inlatex.  TRADE NAME        SUPPLIER__________________________________________________________________________  WINGSTAY L Flake  GOODYEAR  WINGSTAY L Powder GOODYEAR__________________________________________________________________________  Tetrakis(methylene 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)  methane  or  Tetrakis(methylene(3,5-di-t-butyl-4-hydroxyhydrocinnamate) methane   ##STR23##  Mole Weight 1178  White crystalline powder  Melt Point 110-125° C.  Specific Gravity 1.45  TRADE NAME        SUPPLIER__________________________________________________________________________  Irganox 1010      CIBA-GEIGY__________________________________________________________________________  1,3,5-Trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)-benzene   ##STR24##  Mole Weight 775  White crystalline powder  Melt Point 244° C.High performance antioxidant for plastics, rubber, resins and waxes.  TRADE NAME        SUPPLIER__________________________________________________________________________  Ethyl Antioxidant 330                    Ethyl__________________________________________________________________________  1,3,5-Tris(3,5-di-t-butyl-4-hydroxybenzyl)-s-triazine-2,4,6(1H,3H,5H)tri  one  or  1,3,5-Tris(3,5-di-t-butyl-4-hydroxybenzyl)isocyanurate   ##STR25##  White crystalline powder  Melt Point 217-225° C.  Specific Gravity 1.03High temperature antioxidant recommended for plastics.  TRADE NAME        SUPPLIER__________________________________________________________________________  Agerite GT        Vanderbilt  Good-rite 3114    Goodrich  Vanox GT          Vanderbilt__________________________________________________________________________  3:1 Condensate of 3-methyl-6-t-butylphenol with crotonaldehyde  White crystalline powder  Melt Point 182.5-188° C.High performance antioxidant-recommended for plastics.  TRADE NAME        SUPPLIER__________________________________________________________________________  Topanol CA        ICI__________________________________________________________________________  Phenolic condensation products with structures not revealed.General purpose antioxidants for rubber and plastics compounding.                   SPECIFICTRADE NAME    PHYS FORM GRAVITY                          SUPPLIER__________________________________________________________________________Akrochem Antiox 33         White powder                   1.04   Akron Chemical         (M P 100° C. Min.)Akrochem Antiox 36         White powder                   1.05   Akron Chemical         (M P 148° C.)Akrochem Antiox 51         White powder                   1.04   Akron Chemical         (M P 118° C.)Lowinox 22CP46         Powder           LowiMark 328      White powder     ArgusNevastain A   Liquid    1.08-1.09                          NevilleNevastain B   Flake     1.09-1.11                          Neville         (M P 55° C.)Nevastain 76  Amber flake                   1.1    Neville         (M P 134° C.)Stabilite 49-466         Powder    1.04   Reichhold         (M P 110-110° C.)Stabilite 49-467         Powder    1.05   Reichhold         (M P 148° C.)Wytox PDA-S   Tan powder-contains inert carrier                          OlinWytox PMW     Amber powder                   1.05-1.07                          Olin         (M P 122° C.)__________________________________________________________________________  4-((4,6-Bis(octylthio)-s-triazin-2-yl)amino)-2,6-di-t-butylphenol  or  2,4-Bis(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)1,3,5-triazine   ##STR26##  White powder  Melt Point 93-98° C.  TRADE NAME        SUPPLIER__________________________________________________________________________  Irganox 565       CIBA-GEIGY__________________________________________________________________________  Phenol/aldehyde condensatesGeneral purpose antioxidants.                   SPECIFICTRADE NAME    PHYS FORM GRAVITY                          SUPPLIER__________________________________________________________________________Permanax EXP  Brown solid                   1.07   Vulnax         (M P 60° C.)Permanax WMP (1)         Cream powder                   1.54   Vulnax__________________________________________________________________________ (1) Contains an inert carrier 
    
     
         ______________________________________HYDROQUINONE DERIVATIVES______________________________________1.  2,5-Di-t-amylhydroquinone##STR27##    Mole Weight 250    Off-white crystalline powder    Melt Point 179° C.    Specific Gravity 1.02-1.05Polymer stabilizer and shortstop; also used in adhesives;slightly discoloring.TRADE NAME           SUPPLIER______________________________________Santovar A           Monsanto______________________________________2.  t-Butylhydroquinone##STR28##    Mole Weight 166    Off-white crystalline powder    Melt Point 127-129° C.Polymer stabilizer and shortstop.TRADE NAME           SUPPLIER______________________________________Tenox TBHQ           Eastman______________________________________3.  Alkylated hydroquinone (structure not specified)    Viscous liquid (partially    crystallizes)    Specific Gravity 0.90 @ 38° C.Antioxidant-stabilizer for synthetic rubbers and plastics.TRADE NAME           SUPPLIER______________________________________Antioxidant 451      Uniroyal______________________________________ 
    
     
         __________________________________________________________________________PHOSPHITES AND PHOSPHITE BLENDS__________________________________________________________________________  Tris(nonylphenyl)phosphite   ##STR29##  Amber, viscous liquid  Specific Gravity 0.98Non-staining stabilizer for raw polymer SBR and plastics.   TRADE NAME      SUPPLIER__________________________________________________________________________   Interstab CH-55 Interstab   Lowinox TNPP    Lowi   Mark 1178       Argus   Mark 1178B (1)  Argus   Naugard P       Uniroyal   Naugard PHR (1) Uniroyal   Polygard        Uniroyal   Polygard HR (1) Uniroyal   Weston TNPP     Borg-Warner   Weston 399 (2)  Borg-Warner   Weston 399B (2) Borg-Warner   Wytox 312       Olin   Wytox 320       Olin__________________________________________________________________________ (1) Hydrolysis resistant grades (2) More hydrolytically stable, containing TIPA 
    
     
         2.  Bis(2,4-di-t-butyl)pentaerythritol diphosphite   ##STR30##  Mole Weight 604  White crystalline solid  Melt Point 160-175° C.Antioxidant-stabilizer for rubbers and plastics.   TRADE NAME      SUPPLIER__________________________________________________________________________   Weston MDW-626  Borg-Warner__________________________________________________________________________  Distearyl pentaerythritol diphosphite   ##STR31##  Mole Weight 732  White flake  Melt Point 40° C.  Specific Gravity 0.94-0.96Antioxidant for plastics.   TRADE NAME      SUPPLIER__________________________________________________________________________   Weston 618      Borg-Warner   Weston 619 (1)  Borg-Warner__________________________________________________________________________ (1) More hydrolytically stable grade, containing TIPA 
    
     
         4.  `Polymeric` phosphites-structures not disclosedGeneral purpose antioxidants and stabilizers for rubber and plastics.                  SPECIFICTRADE NAME   PHYS FORM GRAVITY SUPPLIER__________________________________________________________________________Wytox 345    Yellow liquid                  0.99    OlinWytox 345-S (1)        White powder      OlinWytox 438    Yellow liquid                  1.01    OlinWytox 438-S (1)        Gray powder       OlinWytox 540    Liquid    1.003   OlinWytox 540-S (1)        Gray powder       Olin__________________________________________________________________________ (1) Solid form on a carrier 
    
     
         5.  Phosphited phenols and bisphenols-structures not revealedGeneral purpose antioxidants for rubber and plastics.                  SPECIFICTRADE NAME   PHYS FORM GRAVITY SUPPLIER__________________________________________________________________________Agerite Geltrol        Liquid    0.955-0.975                          VanderbiltNaugard 492  Liquid    1.008   UniroyalVanox 13     Liquid    0.93    VanderbiltVanox 1005   Liquid    0.955-0.975                          VanderbiltVanox 1013   Liquid    0.93    VanderbiltWytox 604    Liquid    0.89-0.93                          OlinWytox 604-LMS        Liquid    0.948   OlinWytox 604-S (1)        Gray powder       Olin__________________________________________________________________________ (1) Solid form 
    
     
         ______________________________________THIOESTERS______________________________________6.  Phosphite/phenolic antioxidant blendsTRADE NAME           SUPPLIER______________________________________Irganox B215 (1)     CIBA-GEIGYIrganox B225 (2)     CIBA-GEIGYIrganox B900 (3)     CIBA-GEIGYIrganox B1171 (4)    CIBA-GEIGYWeston 800 (5)       Borg-WarnerWeston 801 (6)       Borg-WarnerWeston 802 (7)       Borg-Warner______________________________________Blends of tris-(2,4-di-t-butylphenyl) phosphite and a phenolicantioxidant as follows: (1) 2:1 Blend with tetrakis(methylene(3,5di-t-butyl-4-hydroxy hydrocinnamate))methane(C2) (2) 1:1 Blend with tetrakis(methylene(3,5di-t-butyl-4-hydroxy hydrocinnamate))methane(C2) (3) 4:1 Blend with octadecyl(3,5di-t-butyl-4-hydroxybenzyl)phosphonate(G-1) (4) 1:1 Blend with 1,6hexamethylenebis-(3,5-di-t-butyl-4-hydroxy hydrocinnamide)(G5) 
    
     
         Blends of distearyl pentaerythritol diphosphite (E-3) andtetrakis(methylene 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate)methane as follows: (5) 1:1 Blend (6) 2:1 Blend (7) 3:1 Blend 
    
     
         1.  Dilauryl thiodipropionate or Didodecyl 3,3&#39;-thiodipropionate##STR32##    Mole Weight 515    White waxy solid    Melt Point 40-45° C.    Specific Gravity 1.01Antioxidant for polyolefins and other plastics.TRADE NAME           SUPPLIER______________________________________Argus DLTDP          ArgusCarstab DLTDP        CarstabCyanox LTDP          CyanamidEvanstab 12          EvansLowinox DLTDP        LowiNonox DLTDP          ICI______________________________________2.  Distearyl thiodipropionate or Dioctadecyl 3,3&#39;-thiodipropionate##STR33##    Mole Weight 682    White waxy solid    Melt Point 57-67° C.    Specific Gravity 0.985Antioxidant for polyolefins and other plastics.TRADE NAME           SUPPLIER______________________________________Argus DSTDP          ArgusCarstab DSTDP        CarstabCyanox STDP          CyanamidEvanstab 18          EvansNonox DSTDP          ICI______________________________________3.  Dimyristyl thiodipropionate##STR34##    Mole Weight 571    White waxy solid    Melt Point 44-48° C.Antioxidant for polyolefins and other plastics.TRADE NAME           SUPPLIER______________________________________Argus DMTDP          ArgusCarstab DMTDP        CarstabCYanox MTDP          CyanamidEvanstab 14          Evans______________________________________4.  Ditridecyl thiodipropionate##STR35##    Mole Weight 543    Colorless liquid    Specific Gravity 0.936TRADE NAME           SUPPLIER______________________________________Argus DTDTDP         ArgusCyanox 711           CyanamidEvanstab 13          Evans______________________________________5.  Mixed esters(lauryl and stearyl) of thiodipropionic acid##STR36##    Mole Weight 599    White crystalline powder or flakes    Melt Point 50° C.TRADE NAME           SUPPLIER______________________________________Cyanox 1212          Cyanamid______________________________________6.  Pentaerythritol tetrakis(3-(dodecylthio)propionate)##STR37##    Mole Weight 1162    White solid    Melt Point 50° C. Min.Antioxidant for polyolefins and other plastics.TRADE NAME           SUPPLIER______________________________________Seenox 412-S         Argus______________________________________7.  Blend of a phenolic and thioester type antioxidant.Antioxidant systems for polyolefins.White powderSpecific Gravity 1.04, 1.76 (1)TRADE NAME           SUPPLIER______________________________________Vanox 1030           VanderbiltVanox 1040 (1)       Vanderbilt______________________________________ (1) Contains a mineral deactivator for mineral filled compounds. 
    
     
         __________________________________________________________________________MULTIFUNCTIONAL NON-STAINING ANTIOXIDANTS__________________________________________________________________________  O,ODi-n-octadecyl (3,5-di-t-butyl-4-hydroxybenzyl) phosphonate ##STR38##Mole Weight 805White crystalline powderMelt Point 45° C. Min.Specific Gravity 0.96Antioxidant, stabilizer for plastics.    TRADE NAME          SUPPLIER__________________________________________________________________________    Irganox 1093        CIBA-GEIGY__________________________________________________________________________  1,6-Hexamethylene bis(3,5-di-t-butyl-4-hydroxyhydrocinnamate)  1,6-Hexamethylene bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)  propionate) ##STR39##Mole Weight 639Off-white crystalline powderMelt Point 94-108° C.General purpose antioxidant for plastics and elastomers.     TRADE NAME        SUPPLIER__________________________________________________________________________    Irganox 259        CIBA-GEIGY__________________________________________________________________________  Thiodiethylene bis(3,5-di-t-butyl-4-hydroxy)hydrocinnamate or  Thiodiethylene bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) ##STR40##Mole Weight 642White crystalline powderMelt Point 63° C. Min.Specific Gravity 1.19Antioxidant for plastic and elastomers.    TRADE NAME         SUPPLIER__________________________________________________________________________    Irganox 1035       CIBA-GEIGY__________________________________________________________________________  Octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate or  Octadecyl 3,5-di-t-butyl-4-hydroxyhydrocinnamate ##STR41##Mole Weight 531White crystalline powderSpecific Gravity 1.02Melt Point 49-54° C.Antioxidants for plastics and elastomers.    TRADE NAME         SUPPLIER__________________________________________________________________________    Irganox 1076       CIBA-GEIGY__________________________________________________________________________  N,N&#39;Hexamethylene bis(3,5-di-t-butyl-4-  hydroxyhydrocinnamamide) or  N,N&#39;Hexamethylene bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)  propionamide) ##STR42##Mole Weight 637White crystalline powderSpecific Gravity 1.05Melt Point 156-162° C.Antioxidants for polyamides, plastics and elastomers.    TRADE NAME         SUPPLIER__________________________________________________________________________    Irganox 1098       CIBA-GEIGY__________________________________________________________________________   3,5-Di-t-butyl-4-hydroxyhydrocinnamic acid triester with  1,3,5-Tris(2-hydroxyethyl)-s-triazine-2,4,6-  (1H,3H,5H)trione ##STR43##                ##STR44##Mole Weight 1042White crystalline powderSpecific Gravity 0.921Melt Point 123-131° C.Antioxidant for plastics.    TRADE NAME         SUPPLIER__________________________________________________________________________    Good-rite 3125     Goodrich    Agerite SKT, Vanox SKT                       Vanderbilt__________________________________________________________________________  NButyryl-p-aminophenol or N(4-Hydroxyphenyl)butyramide ##STR45##Mole Weight 179White powderMelt Point 136-141° C.Antioxidants for plastics and elastomers.    TRADE NAME         SUPPLIER__________________________________________________________________________    Suconox 4          Hexel__________________________________________________________________________  NPelargonoyl-p-aminophenol or N(4-Hydroxyphenyl)pelargonamide ##STR46##Mole Weight 249White powderMelt Point 121-125° C.Antioxidant for plastics and elastomers.    TRADE NAME         SUPPLIER__________________________________________________________________________    Suconox 9          Hexel__________________________________________________________________________  NLauroyl-p-aminophenol or N(4-Hydroxyphenyl)dodecanamide ##STR47##Mole Weight 291White powderMelt Point 130-134° C.Antioxidant for plastics, butyl rubber and elastomers.    TRADE NAME         SUPPLIER__________________________________________________________________________    Suconox 12         Hexel__________________________________________________________________________10.  NStearoyl-p-aminophenol or N(4-Hydroxyphenyl)stearamide ##STR48##Mole Weight 376White powderMelt Point 130-134° C.Antioxidant for polyethylene and polyamides.    TRADE NAME         SUPPLIER__________________________________________________________________________    Suconox 18         Hexel__________________________________________________________________________  2,6-Di-t-butyl-alpha-dimethylamino-p-cresol or  2,6-Di-t-butyl-4-(dimethylaminomethyl)phenol ##STR49##Mole Weight 263Light yellow crystalline powderMelt Point 94° C.Antioxidant for plastics and elastomers    TRADE NAME         SUPPLIER__________________________________________________________________________    Ethyl Antioxidant 703                       Ethyl__________________________________________________________________________  1,3,5-Tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-2,4,6-(1H,  3H,5H)trione ##STR50##                ##STR51##Mole Weight 699Off-white powderMelt Point 145-155° C.    TRADE NAME         SUPPLIER__________________________________________________________________________    Cyanox 1790        Cyanamid__________________________________________________________________________  Nickel bis(Oethyl(3,5-di-t-butyl-4-hydroxybenzyl)phosphonate) ##STR52##Mole Weight 714Tan-light green powderMelt Point 180° C. Min.Antioxidant/UV absorber for plastics.    TRADE NAME         SUPPLIER__________________________________________________________________________    Irgastab 2002      CIBA-GEIGY__________________________________________________________________________  2,2&#39;-Oxamidobisethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)  propionate ##STR53##Mole Weight 697Off-white powderMelt Point 173° C.Antioxidant and metal deactivator.    TRADE NAME          SUPPLIER__________________________________________________________________________    Naugard XL-1       Uniroyal__________________________________________________________________________  Phenolic antioxidant/metal deactivator - undisclosed  composition.          SPECIFICTRADE NAME     GRAVITY   MELT POINT                              SUPPLIER__________________________________________________________________________Irganox MD-1024          1.12      224° C. Min.                              CIBA-GEIGY__________________________________________________________________________  Tris(2-t-butyl-4-(2-methyl-4-hydroxy-5-t-butylphenylthio)-5-methyl)pheny  lphosphite ##STR54##Mole Weight 1103Antioxidant and metal deactivator                    SPECIFICTRADE NAME     PHYS FORM GRAVITY   SUPPLIER__________________________________________________________________________Antioxidant VP OSP 1          White powder                    1.10      Hoechst__________________________________________________________________________  Bis(3,3-bis(4-hydroxy-3-butylphenyl)butanoic acid)glycolesterMole Weight 795Melt Point 170° C.                    SPECIFICTRADE NAME     PHYS FORM GRAVITY   SUPPLIER__________________________________________________________________________Hostanox 03    White powder                    1.1       Hoechst__________________________________________________________________________  Tetrakis(2,4-di-t-butylphenyl)4,4&#39;-biphenylylenediphosphonite ##STR55##Mole Weight 1035                    SPECIFICTRADE NAME     PHYS FORM GRAVITY   SUPPLIER__________________________________________________________________________Sandostab P-EPQ          75° C.                    1.045     Sandoz__________________________________________________________________________  n-Propyl gallate or n-Propyl 3,4,5-tri-hydroxybenzoate ##STR56##Mole Weight 212White powderMelt Point 146-148° C.    TRADE NAME         SUPPLIER__________________________________________________________________________    Tenox PG           Eastman__________________________________________________________________________20.  Calcium bis(Oethyl(3,5-di-t-butyl-4-  hydroxybenzyl)phosphonate) ##STR57##Mole Weight 647Off-white powderMelt Point &gt;260° C.Antioxidant/metal deactivator.    TRADE NAME         SUPPLIER__________________________________________________________________________    Irganox 1425       CIBA-GEIGY__________________________________________________________________________  Phenolic Antioxidant - composition undisclosed.Antioxidant/metal deactivator.TRADE NAME          PHYSICAL FORM SUPPLIER__________________________________________________________________________Lowinox 22CP46-MD   Off-white powder                             Lowi__________________________________________________________________________ 
    
     
         ______________________________________MISCELLANEOUS UNCLASSIFIEDNON-STAINING ANTIOXIDANTS AND BLENDS______________________________________1.  1.2-Mercapto-4(5)-methylbenzimidazole ##STR58##Mole Weight 164Yellow-white powderSpecific Gravity 1.25Melt Point 270° C.Antioxidant, synergist and metal deactivator.TRADE NAME           SUPPLIER______________________________________Vulkanox MB-2/MG     Mobay______________________________________2.  Zinc salt of 2-mercaptobenzimidazole ##STR59##White powderSpecific Gravity 1.75Melt Point &gt;300° C.with decomposition.Antioxidant and synergist.TRADE NAME           SUPPLIER______________________________________Akrochem Antioxidant 58                Akron ChemicalNaugard ZMB          Uniroyal______________________________________3.  2-Mercapto-4-methylbenzimidazole,zinc salt,    2-Mercapto-5-methylbenzimidazole,zinc salt ##STR60##Mole Weight 392       SPECIFIC    MELTTRADE NAME  GRAVITY     POINT     SUPPLIER______________________________________Vulkanox ZMB-2/C       1.75        &gt;300° C.                             Mobay______________________________________4.  Antioxidants of undisclosed composition, including blends.TRADE NAME    PHYS FORM     SUPPLIER______________________________________Mark 1220     Yellow liquid ArgusMark 1475(1)  White powder  ArgusMark 2112     White powder  ArgusMark 2183(1)  Tan powder    Argus______________________________________ (1)Antioxidant/chelator. 
    
     
         5.  Phosphite/phenolic antioxidant blends                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Mark 1409   Liquid      0.99      ArgusMark 1409-S(1)       Granules    1.18      Argus______________________________________ (1)Solid form of Mark 1409 
    
     
         6.  Thioester/phenolic antioxidant blendsGeneral purpose antioxidants used mainly in plastics.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Mark 158    Yellow liquid                   0.982     ArgusMark 1589   White powder                   1.17      ArgusMark 1589B  White powder                   1.17      Argus______________________________________7.  2-Mercaptotoluimidazole ##STR61##Mole Weight 164Melt Point 250° C. Min.Non-staining antioxidant and synergist.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Vanox MTI   Tan powder  1.33      Vanderbilt______________________________________8.  Zinc 2-mercaptotoluimidazole ##STR62##Mole Weight 391Non-staining antioxidant and synergist.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Vanox ZMTI  Tan powder  1.69      Vanderbilt       Melt Point       &gt;300° C.______________________________________9.  Dioctadecyl disulfideH.sub.38 C.sub.18SSC.sub.18 H.sub.38              Mole Weight 571              Melt Point 53-58° C.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Antioxidant SE10       White powder                   0.85 @    Hoechst                   55° C.______________________________________10. Blends including a phenolic antioxidant-undisclosed    composition.       SPECIFIC    MELTTRADE NAME  GRAVITY     POINT     SUPPLIER______________________________________Antioxidant AO-19       1.03        110-200° C.                             SovereignAntioxidant 35       1.04        105-115° C.                             SovereignPowderAntioxidant 872       1.03        122° C.                             Sovereign______________________________________11. Blend of non-staining antioxidants                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Permanax CNS       Cream powder                   1.25      Vulnax       Melt Point       298° C.______________________________________12. Metal aromatic sulfonateMineral deactivator.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Vanox 3240  Brown liquid                   0.98      VanderbiltVanox 3245  Brown flake 1.12      Vanderbilt______________________________________ 
    
     
         ______________________________________NAPHTHYLAMINES______________________________________1. NPhenyl-alpha-naphthylamine ##STR63##           Specific Gravity 1.16-1.20Melt Point 50-59°               C.an-purple powderMole Weight 219TRADE NAME          SUPPLIER______________________________________Additin 30          MobayAkrochem Antioxidant PANA               Akron ChemicalNaugard PAN         Uniroyal______________________________________2. NPhenyl-beta-naphthylamine (Commonly called `PBNA`) ##STR64##           Specific Gravity 1.18-1.24Melt Point 105-106°               C.Dark SolidMole Weight 219Powerful staining antioxidant extensively used in Europe.No known suppliers in the USA.______________________________________ 
    
     
         __________________________________________________________________________DIPHENYLAMINE AND OTHERDIARYLAMINE DERIVATIVES__________________________________________________________________________1. p-Oriented styrenated diphenylamine ##STR65##                    Amber viscous liquid                    Specific Gravity 1.08Mostly di substituted with some mono and tri substituted species.Some ortho substitution.Highly active non-staining, mildly discoloring amine for natural andsyntheticpolymers and compounds.TRADE NAME               SUPPLIER__________________________________________________________________________WINGSTAY 29              GOODYEARWINGSTAY 29 Powder (1)   GOODYEARLowinox SDA (2)          LowiVulkanox DDA (2)         Mobay__________________________________________________________________________(1) Solid form of WINGSTAY 29-70% active - Specific Gravity 1.53(2) Orientation and amount of styrenation not listed.__________________________________________________________________________2. Octylated diphenylamines ##STR66##General purpose semi-staining antioxidants for polymers and compounds                     SPECIFICTRADE NAME     PHYS FORM             MELT POINT                     GRAVITY                           SUPPLIER__________________________________________________________________________Agerite Gel (1)     Tan waxy solid             40-50° C.                     0.94  VanderbiltAgerite Stalite S     Tan powder             89-103° C.                     1.02  VanderbiltAkrochem Antiox S     Brown granules             88° C. Min.                     1.00  Akron                           ChemicalCyanox 8  Gray flakes             75-85° C.                     0.98  CyanamidFlectol ODP     Tan powder             89-103° C.                     0.99  MonsantoOctamine  Tan solid             85° C. Min.                     0.99  UniroyalPennox ODP     Tan powder             88-98° C.                     1.02  PennwaltPermanax OD     Tan granules             90° C.                     1.12  VulnaxVanox 12  Tan granules             94-100° C.                     1.01  VanderbiltVanox 1081     Tan granules             94-100° C.                     1.02  VanderbiltVulkanox OCD     Tan granules             90° C.                     1.12  Mobay__________________________________________________________________________(1) Contains 25% wax__________________________________________________________________________3. Other alkylated diphenylamines ##STR67##General purpose semi-staining antioxidants.                  SPECIFICTRADE NAME    PHYS FORM                  GRAVITY SUPPLIER__________________________________________________________________________Agerite NEPA (1)         Amber liquid                  0.935   VanderbiltAgerite Stalite (2)         Dark liquid                  1.01    VanderbiltPennox A (2)  Dark liquid                  0.995-1.025                          PennwaltPermanax HD (3)         Brown liquid                  0.97    VulnaxPermanax HD(SE) (4)         Brown liquid                  0.97    VulnaxPolylite (5)  Dark liquid                  0.95    UniroyalVanox 1001 (1)         Amber liquid                  0.935   VanderbiltWytox ADP-F (1)         Gray flake                  0.99    Olin__________________________________________________________________________(1) Alkylation not specified(2) Octylated(3) Heptylated(4) Self emulsifying form(5) Nonylated__________________________________________________________________________4. High temperature reaction products of diphenylamine and acetonePowerful amine antioxidants for rubber compounds used frequently toimpart high temperature resistance. Rather severe staining.                  SPECIFICTRADE NAME    PHYS FORM                  GRAVITY SUPPLIER__________________________________________________________________________Agerite Superflex (1)         Dark liquid                  1.10    VanderbiltAgerite Superflex         Dk br powder                  1.33    VanderbiltSolid G (3)Agerite Superflex         Dk brown rods                  1.34    VanderbiltSolid Rodform (2)BLE-25        Dark br liquid                  1.10    UniroyalBLE-75        Dk br powder                  1.33    UniroyalPermanax BL   Brown liquid                  1.09-1.10                          VulnaxPermanax BLN  Brown liquid                  1.09-1.10                          VulnaxPermanax BLW (5)         Brown solid                  1.26    Vulnax__________________________________________________________________________(1) Contains 20% diphenylamine(2) 32.5% Inert carrier(3) 15% Diphenylamine, 25% inert carrier(4) 75% Active on micro-cel(5) Contains a silicate carrier__________________________________________________________________________5. Low temperature reaction product of diphenylamine and acetone                    Brown-green powder                    Specific Gravity 1.15General purpose antioxidant.TRADE NAME     MELT POINT                    SUPPLIER__________________________________________________________________________Aminox         85-95° C.                    UniroyalPermanax B     75-90° C.                    Vulnax__________________________________________________________________________6. Diarylamine/ketone/aldehyde reaction products                    Dark brown solids                    Melt point 85-95° C.                    Specific Gravity 1.15General purpose antioxidants.TRADE NAME               SUPPLIER__________________________________________________________________________BXA-G                    UniroyalNaugard BG               UniroyalVanox AT                 Vanderbilt__________________________________________________________________________7. Substituted diphenylamine - structure not revealed                    Off-white powder                    Melt Point 96-99° C.                    Specific Gravity 1.14Non-discoloring amine antioxidant for polymers and plastics.TRADE NAME               SUPPLIER__________________________________________________________________________Naugard 445              Uniroyal__________________________________________________________________________ 
    
     
         __________________________________________________________________________p-PHENYLENEDIAMINES__________________________________________________________________________1. NPhenyl-N&#39;(1,3-dimethylbutyl)-p-phenylenediamine ##STR68##                 Specific Gravity 1.02Melt Point 45-50°                     C.Gray-black solid or semi-solidMole Weight                     268Powerful and persistent antioxidant, flex crack inhibitor andantiozonant.TRADE NAME                SUPPLIER__________________________________________________________________________WINGSTAY 300              GOODYEARAkrochem Antiozonant PD #2                     Akron ChemAnto 3E                   PennwaltAntozite 67               VanderbiltAntozite 67F (1)          VanderbiltFlexzone 7F, (1)          UniroyalFlexzone 7L               UniroyalPermanax 6PPD             VulnaxSantoflex 13              MonsantoSantoflex 13F, (1)        MonsantoUOP 588                   UOPVulkanox 4020             MobayVulkanox 4020 Flake (1)   Mobay__________________________________________________________________________(1) Flaked form__________________________________________________________________________2. NPhenyl-N&#39;isopropyl-p-phenylenediamine ##STR69##                 Specific Gravity 1.14-1.17Melt Point                     70-77° C.Purple black flakesMole Weight                     226Powerful antioxidant-antiozonant.TRADE NAME                SUPPLIER__________________________________________________________________________Akrochem Antiozonant PD #1                     Akron ChemAnto 3H                   PennwaltFlexzone 3C               UniroyalPermanax IPPD             VulnaxSantoflex IP              MonsantoVulkanox 4010NA           Mobay__________________________________________________________________________3. NPhenyl-N&#39;(1-methylheptyl)-p-phenylenediamine ##STR70##                 Specific Gravity 1.00Dark brown liquidMole                     Weight 296Antioxidant-antiozonant.TRADE NAME                SUPPLIER__________________________________________________________________________UOP 688                   UOP__________________________________________________________________________4. NPhenyl-N&#39;cyclohexyl-p-phenylenediamine                     Mole Weight 266 ##STR71##                 Specific Gravity 1.29Melt Point                     103-107° C.Gray-violet flakesAntioxidant-antiozonant.TRADE NAME                SUPPLIER__________________________________________________________________________Flexzone 6H               Uniroyal__________________________________________________________________________5. Mixed diaryl-p-phenylenediamines ##STR72##                 may be H or CH3R,R&#39;,R&#34;, and R&#39;&#34;Persistent antioxidants, antiozonants and antiflex agents for manynatural and syntheticrubber compounds. Very powerful antiozonants for CR. Very non-volatileand slow to extract.       PHYSICAL    MELT  SPECIFICTRADE NAME  FORM        POINT GRAVITY                               SUPPLIER__________________________________________________________________________WINGSTAY 100       Silver-gray flakes                   90-105° C.                         1.18  GOODYEARWINGSTAY 100AZ (1)       Gray flakes 110° C.                         1.18  GOODYEARWINGSTAY 200       Low melting semi-solid                   60° C.                         1.18  GOODYEAR__________________________________________________________________________(1) Special low scorch grade for neoprene (CR)__________________________________________________________________________6. N,N&#39;Diphenyl-p-phenylenediamine                     Mole Weight 260 ##STR73##                 Specific Gravity 1.21Melt Point 136°                     C.Gray flakesGeneral purpose antioxidant and flex crack inhibitor. Limited solubilityin most polymers.TRADE NAME                SUPPLIER__________________________________________________________________________Agerite DPPD              VanderbiltJ-Z-F                     UniroyalNaugard J                 UniroyalPermanax DPPD             Vulnax__________________________________________________________________________7. N,N&#39;Di-beta-naphthyl-p-phenylenediamine ##STR74##                 Specific Gravity 1.25Melt Point                     224-230° C.Gray to tan powderMole Weight                     360Antioxidant and metal deactivator. Not an antiozonant.TRADE NAME                SUPPLIER__________________________________________________________________________Agerite White             VanderbiltAgerite White White (1)   Vanderbilt__________________________________________________________________________(1) Special grade__________________________________________________________________________8. N,N&#39;Bis(1,4-dimethylpentyl)-p-phenylenediamine ##STR75##                 Specific Gravity 0.90Red-brown liquidMole                     Weight 304.5General purpose antiozonant. Activates cure systems.TRADE NAME                SUPPLIER__________________________________________________________________________Flexzone 4L               UniroyalSantoflex 77              MonsantoUOP 788                   UOP__________________________________________________________________________9. N,N&#39;Bis(1-ethyl-3-methylpentyl)-p-phenylenediamine ##STR76##                 Specific Gravity 0.87-0.93Red-brown liquidMole                     Weight 332.5General purpose antiozonant. Activates cure systems.TRADE NAME                SUPPLIER__________________________________________________________________________Antozite 2                VanderbiltFlexzone 8L               UniroyalUOP 88                    UOP__________________________________________________________________________10. N,N&#39;Bis(1-methylheptyl)-p-phenylenediamine ##STR77##                 Specific Gravity 0.90Melt Point 38°                     C.Red-brown liquidMole Weight 332.5General purpose antiozonant. Activates cure systems.TRADE NAME                SUPPLIER__________________________________________________________________________Antozite 1                VanderbiltSantoflex 217             MonsantoUOP 288                   UOP__________________________________________________________________________11. NPhenyl-N&#39;(p-toluenesulfonyl)-p-phenylenediamine                     Mole Weight 324 ##STR78##                 Specific Gravity 1.35Melt Point 146° C.                     Min.Gray powderSemi-discoloring antioxidant and copper inhibitor.TRADE NAME                SUPPLIER__________________________________________________________________________Aranox                    Uniroyal__________________________________________________________________________ 
    
     
         ______________________________________QUINOLINES______________________________________1.  Polymerized 2,2,4-trimethyl-1,2-dihydroquinoline ##STR79##General purpose semi-staining antioxidant used in dry rubber andlatex compounding. Used to impart high temperature resistance.Functions As a mild antiozonant. Specific Gravity 1.04-1.08                   MELTTRADE NAME  PHYS FORM   POINT     SUPPLIER______________________________________Agerite MA  Tan powder  74° C. Min.                             VanderbiltAgerite ME Pellets       Tan pellets 74° C. Min.                             VanderbiltAgerite PE Pellets       Amber pellets                   88° C. Min.                             VanderbiltAgerite Resin D       Amber pellets                   74° C. Min.                             VanderbiltAgerite Resin D       Amber powder                   74° C. Min.                             VanderbiltPowderAkrochem    Amber powder                   75° C. Min.                             AkronAntioxidant DQ                    ChemicalCyanox 12   Tan powder  75-110° C.                             Cyanamid       or flakesFlectol H   Tan powder  75-110° C.                             MonsantoLowinox ACP                       LowiNaugard Q   Amber powder                   75° C. Min.                             UniroyalPennox HR Flake       Tan flake   75-110° C.                             PennwaltPennox HR Powder       Tan powder  75-110° C.                             PennwaltPermanax TQ Brown flake 79° C. Min.                             VulnaxVulkanox HS Amber pellets                   75° C.                             Mobay______________________________________2.  6-Dodecyl-2,2,4-trimethyl-1,2-dihydroquinoline ##STR80##Mole Weight 342General purpose antioxidant.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Santoflex DD       Dark liquid 0.90-0.96 Monsanto______________________________________3.  6-Ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline ##STR81##Mole Weight 217Highly staining antioxidant and antiozonant.                   SPECIFICTRADE NAME PHYS FORM    GRAVITY   SUPPLIER______________________________________Santoflex AW      Dark liquid  1.02-1.05 MonsantoVulkanox EC      Dark liquid  1.02-1.05 Mobay______________________________________ 
    
     
         ______________________________________BLENDED AMINES______________________________________1.  65% Dioctylated diphenylamine (J-2) and 35% N,N&#39;--    diphenyl-p-phenylenediamine (K-6)Antioxidant and flex cracking inhibitor.Melt Point 80-100° C.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Agerite HP-S       Black powder                   1.11      VanderbiltAgerite HP-S       Black Rodform                   1.11      VanderbiltRodform______________________________________2.  50% Octylated diphenylamine (J-2), 25% N,N&#39;--diphenyl-p-    phenylenediamine (K-6) and 25% high temperature reaction    product of diphenylamine and acetone. (J-4)Antioxidant and flex cracking inhibitor.Melt Point 70° C. Min.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Agerite Hipar T       Brown powder                   1.15      Vanderbilt______________________________________3.  65% Diarylamine/ketone reaction product and    35% N,N&#39;--diphenyl-p-phenylenediamine (K-6)Antioxidant, flex cracking inhibitor and metal deactivator.Melt Point 87-99° C.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Flexamine   Brown powder                   1.17      UniroyalFlexamine G Brown granules                   1.17      Uniroyal______________________________________4.  p-Phenylenediamine antiozonant blends-undisclosed    composition.TRADE NAME     PHYS FORM     SUPPLIER______________________________________Flexzone 10L   Dark liquid   UniroyalFlexzone 11L   Dark liquid   UniroyalFlexzone 12L   Dark liquid   UniroyalFlexzone 15L   Dark liquid   UniroyalSantoflex 134  Dark liquid   MonsantoUOP 57 (1)     Dark liquid   UOPUOP 62 (2)     Dark liquid   UOPUOP 256 (3)    Dark liquid   UOP______________________________________ (1) Blend of UOP 588 and UOP 788 (2) Blend of UOP 288 and UOP 688 (3) Blend of UOP 288, UOP588 and UOP688 
    
     
         5.  Blend of 50% N,N&#39;--bis(1,4-dimethylpentyl)-p-phenylene-    diamine(K-8) and 50% N--phenyl-N&#39;--(1,3-    dimethylbutyl)-p-phenylenediamine(K-1)General purpose antiozonant blend.TRADE NAME     PHYS FORM     SUPPLIER______________________________________Flexzone 9L    Dark liquid   Uniroyal______________________________________6.  Antidegradant blends-undisclosed composition.General purpose antidegradant which may or may not be anantiozonant.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Naugard 477 Brown powder                   1.18      UniroyalPermanax CR Brown granules                   1.14      Vulnax______________________________________7.  Antidegradant blendsGeneral purpose antidegradants.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Santoflex LC (1)       Dark liquid 1.023     MonsantoSantoflex 134D (2)       Dark liquid 0.96      MonsantoSantoflex 715 (3)       Dark liquid 0.98      Monsanto______________________________________  (1) 1 Part N--(1,3dimethylbutyl)-N&#39;--phenyl-p-phenylenediamine (K1), 1 part N--(1,4dimethylpentyl)-N&#39;--phenyl-p-phenylenediamine and 4 parts 6ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline (L3) (2) 162/3% N--(1,3Dimethylbutyl)-N&#39;--phenyl-p-phenylenediamine (K1), 331/3% N--(1,4dimethylpentyl)-N&#39;--phenyl-p phenylenediamine and 50% 6dodecyl-2,2,4-trimethyl-1,2 dihydroquinoline (L2) (3) 42% N--(1,3Dimethylbutyl)-N&#39;--phenyl-p-phenylenediamine (K1), 42% N--(1,4dimethylpentyl)-N&#39;--phenyl-p-phenylenediamine and 16% N,N&#39;--bis(1,4dimethylpentyl)-p-phenylenediamine (K8) 
    
     
         8.  Mixture of an alkylated mercaptobenzimidazole and an    amine antioxidant                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Stangard 500       Tan powder  1.24      Harwick______________________________________9.  Amine antioxidant blend-undisclosed composition                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Vanox 200   Brown liquid                   1.13      VanderbiltVanox 200 Powder       Brown powder                   1.40      Vanderbilt______________________________________ 
    
     
         ______________________________________MISCELLANEOUS UNCLASSIFIEDANTIOXIDANTS AND ANTIOZONANTS______________________________________1.  Nickel dibutyldithiocarbamate ##STR82##Mole Weight 467Melt Point 86° C. Min.Antiozonant for SBR and NBR antioxidant for severalspeciality polymers.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Akrochem Nibud       Green solid 1.27      Akron                             ChemicalNaugard NBC Green solid 1.27      UniroyalNBC         Green solid 1.26      duPontVanox NBC   Green solid 1.27      Vanderbilt______________________________________2.  Nickel diisobutyldithiocarbamate ##STR83##Mole Weight 467Melt Point 173-181° C.Antiozonant for SBR and NBR; antioxidant for severalspecialty polymers.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Isobutyl Niclate       Green powder                   1.27      Vanderbilt______________________________________3.  Nickel dimethyldithiocarbamate ##STR84##Mole Weight 299Specialty antioxidant and antiozonant.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Methyl Niclate       Green powder                   1.77      Vanderbilt______________________________________4.  3,9-Bis(3-cyclohexenyl)-2,4,8,10-tetraoxaspiro(5,5)undecaneNon-staining antiozonant.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Vulkanox AFS/LG       Gray powder 1.06 @    Mobay                   90° C.______________________________________5.  Unsaturated acetal absorbed on clayNon-staining antiozonant.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Akrochem    Gray powder 1.74      AkronAntiozonant E-9604                Chemical______________________________________ 
    
     The preceding listing of antioxidants is taken from a trade publication entitled: Index of Commercial Antioxidants &amp; Antiozonants 3rd Edition (1982), distributed by the Goodyear Chemicals division of Goodyear Tire and Rubber Co., Akron, OH. That publication does not recommend any of the listed antioxidants specifically for inclusion in polyvinyl chloride compositions, and only recommends the following antioxidants: 
     N,N&#39;-hexamethylene bis (3,5-di-t-butyl-4-hydroxyhydrocinnamamide); 
     N,N&#39;-hexamethylene bis (3-(3,5-di-t-butyl-4-hydroxyphenyl) propionamide; 
     N-stearoyl-p-aminophenol; and 
     N-(4-hydroxyphenyl)stearamide; 
     specifically for inclusion in polyamides. (Many of the other listed antioxidants are recommended for inclusion in &#34;plastics&#34; without further definition of a composition.) This index does not suggest inclusion of antimicrobial materials in conjunction with the indicated antioxidants. 
     SUMMARY OF THE INVENTION 
     The essence of the present invention resides in the discovery that compositions and articles containing antimicrobial agents can be processed at relatively high temperatures, even when exposing a large surface area to the ambient atmosphere or other sources of oxygen (as when forming films or fibers), if the composition also contains an antioxidant (sometimes referred to herein as a &#34;stabilizer&#34;). Antioxidants have not previously been used to stabilize antimicrobial agents. Both the discovery of the nature of the oxidation problem and the discovery of its solution are facets of the present invention. 
     One aspect of the invention is an antimicrobial composition having improved resistance to degradation of antimicrobial activity as a result of exposure of said composition to heat. The composition comprises an antimicrobial agent and an antioxidant. 
     A second aspect of the invention is an unprocessed thermoplastic composition which will be resistant to microbial attack after being processed at an elevated temperature. This composition comprises a resin selected from the group consisting of polypropylene, polyamides, and polyvinyl chloride; an antimicrobial agent; and a amount of an antioxidant effective to reduce degradation of the antimicrobial agent while the composition is being melt processed. 
     A third aspect of the invention is an article, such as a film or fiber, having resistance to microbial attack. The article comprises a polymeric resin as described in the preceding paragraph, an antimicrobial agent, and an antioxidant. These components are combined to form a composition before the composition is melt processed to form the article. 
     Method aspects of the invention are also contemplated. One is a method for preserving the efficacy of an antimicrobial agent against heat-induced degradation, comprising the step of adding to the antimicrobial agent an effective amount of an antioxidant. Another is a method for melt processing a composition comprising a thermoplastic resin and an antimicrobial agent while maintaining the efficacy of the antimicrobial agent. This method comprises the steps of combining a thermoplastic resin, an antimicrobial agent, and an antioxidant, followed by melt processing the composition. &#34;Melt processing&#34; means the manipulation of the composition at an elevated temperature, which is typical when forming the composition into a useful article, particularly a fiber or film which has a large surface to volume ratio. 
     The compositions of the invention have a substantial advantage over unstabilized prior compositions. Either less of the antimicrobial agent can be used to provide a desired level of antimicrobial activity, or a given amount of the antimicrobial agent can provide greater activity. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Compositions according to the present invention comprise one part by weight of an antimicrobial agent and from 0.1 to 50 parts, preferably from 1 to 5 parts by weight of an additive referred to here as a &#34;stabilizer&#34; which prevents thermal and oxidative degradation of the antimicrobial agent in the composition. 
     The contemplated antimicrobial agents stabilized according to the present invention include all those specified in the Background Art section, others known to those of ordinary skill in the art, and mixtures thereof. The preferred antimicrobial agents are as follows: 
     10,10&#39;-oxybisphenoxarsine (OBPA); 
     10,10&#39;-oxybisphenarsazine; 
     bis-n-tributyltin oxide; 
     zinc Omadine; and 
     N-(trichloromethylthio)cyclohexenedicarboxamide. 
     Broadly speaking, the stabilizers contemplated herein can be any material which is stable with respect to the selected antimicrobial agent and under melt processing conditions and which will protect the chosen antimicrobial agent against degradation due to exposure of the composition to heat and oxygen. Epoxidized soybean oil also has utility as an antioxidant. 
     The preferred antioxidants contempleted herein are selected from the group consisting of: hindered phenols (examples of which are 2,6-di-t-butyl-p-cresol or 2,6-di-t-butyl-4-methylphenol); polyphenols (an example of which is tetrakis(methylene-3-(3,5-di-t-butyl-4-hydroxyhydrocinnamate))methane, sold by Ciba-Geigy Corporation as Irganox 1010; phosphites (an example of which is tris-(2,4-di-t-butylphenyl)phosphite, sold by Ciba-Geigy Corporation, under the trade name Irgafos 168 and as a 1:1 mixture with N,N&#39;-hexamethylene-bis-(3,5-di-t-butyl-4-hydroxyhydrocinnanamide) (Irganox 1098) under the trade name Irganox B 1171); thioesters (e.g. distearyl thiodipropionate); 1,3,5-tris(4-t-butyl-3-hydroxy-2,6-dimethylbenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione; nickel bis (0-ethyl(3,5-di-t-butyl-4-hydroxylbenzyl)phosphonate; zinc 2-mercaptobenzimidazole; aromatic amines (such as N-phenyl-alpha-naphthylamine or alkylated diphenylamines); and combinations of the above. 
     The synergists contemplated herein are compounds which render the stabilizers more effective, typically by increasing the efficacy of the chosen stabilizer as an antioxidant for the antimicrobial compound. Two exemplary synergists are distearylthiodipropionate (DSTDP) and tris-(2,4-di-t-butylphenyl) phosphite. Other contemplated synergists, which also have utility as antioxidants, are the following compounds 
     2-mercapto-4-methylbenzimidazole; 
     2-mercapto-5-methylbenzimidazole; 
     zinc salt of 2-mercaptobenzimidazole; 
     2-mercaptotoluimidazole; and 
     zinc 2-mercaptotoluimidazole. 
     These are listed as compounds H-1 (2 entries), H-2, H-7, and H-8 in the preceding list of antioxidants. Other synergists known to the art are also contemplated for use herein. 
     A third ingredient contemplated within the scope of the present invention is a predominant proportion of a polymeric resin, optional including the usual modifiers and process aids employed in the rubber and plastic formulation arts. Two resin compositions are particularly contemplated herein. First is a concentrate composition containing 1 to 80 per cent (all numbers stated herein are by weight unless otherwise indicated) of an antimicrobial agent, a stabilizer, and enough of a polymeric resin to improve the dispersibility of the other ingredients. Second is a composition containing at least about 90% of the resin, preferably from 99 to about 99.99 percent of the resin, and a minor proportion of the antimicrobial agent and its stabilizer. The first composition has utility as a concentrated antimicrobial agent premix which can be readily and uniformly dispersed in a resin composition. The second composition has direct utility as a thermoplastic resin composition for fabrication into useful articles having antimicrobial protection. Other proportions of ingredients are also contemplated. 
     The resins contemplated for use herein are exemplified by the description in the Background Art section of the specification. Other resins not specified herein are also contemplated within the scope of the invention. The preferred resins are polyamides and polyvinyl chloride, which derive particular benefit from the invention because they are not conventionally compounded with resin antioxidants. Optional resin modifiers contemplated herein include plasticizers; extenders; stabilizers to deter degradation caused by environmental heat and light; fillers; dyes and pigments; flame retardants; lubricants; blowing agents; and so forth. The additives chosen for a particular composition are determined by the desired properties of the final composition. The range of possible additives is limited only by the need to ensure compatibility of all the components of the final composition. 
     The desired concentrations of the antimicrobial agent and additives in resin compositions are a complex function of the inherent activity of the agent, the tendency toward thermal degradation in other ingredients such as the resin, and the temperature and duration of fabrication. Generally the amount of additive desired is from 0.1 to 50 times, and preferably from about one to about five times the amount of the antimicrobial agent, and the active antimicrobial agent desirably comprises from 0.005% (50 ppm) to 1.0% (10,000 ppm) by weight of the thermoplastic composition. One exemplary unprocessed thermoplastic composition according to the present invention contains from about 170 to about 450 ppm (preferably 220 ppm) of the selected antimicrobial agent and enough of the selected antioxidant that, following heat processing, at least 100 ppm of the active antimicrobial agent will remain. Another exemplary unprocessed thermoplastic composition according to the present invention contains from about 85 to about 220 ppm of the selected antimicrobial agent, and enough of the chosen antioxidant that, after heat processing, at least 50 ppm of the active antimicrobial agent will remain. 
     It will be appreciated that the ratio: ##EQU1## will depend on the selection of the antimicrobial agent, the identity and amount of the resin and modifiers selected, the processing conditions, and other factors, so no universal ratio can be stated. However, inclusion of an effective antioxidant will always bring the above-stated ratio nearer to its ideal value of 1.0. 
     In the preferred OBPA composition containing nylon, OBPA, and an amount of an antioxidant sufficient to provide protection during heat processing, the ratio of initial OBPA to final OBPA is about 0.60. Thus, if at least about 100 ppm of OBPA is desired in a fiber, about 170 ppm to about 450 ppm of OBPA is incorporated in the original composition. (If the antioxidant were absent, a final effective level of 100 ppm in nylon fibers would require incorporation of about 500 ppm--three times the level of addition required if the present invention is practiced.) If at least about 50 ppm of OBPA is desired in a fiber, from about 85 to about 220 ppm of OBPA and an effective amount of an antioxidant are incorporated in the composition. 
     A preferred method for preparing the stabilized plastic compounds is to prepare a blend of the selected resin and antimicrobial agent in which the antimicrobial agent is included in a concentrate as described by Rei in U.S. Pat. No. 4,086,297. The patent is hereby incorporated herein by reference. The blend is then mixed with the desired resin and modifiers. 
     Compositions specifically contemplated for use herein include those comprising polycaprolactam resin, OBPA as an antimicrobial agent, and a phosphite stabilizer. Nylon is selected because of its desirable properties as a fiber, particularly as a carpet fiber. Nylon fibers are also formed at a high temperature, for example about 285° C. for Nylon 6 (300° C. for Nylon 6,6), and thus antimicrobial agents contained in nylon compositions have previously been substantially or completely inactivated during processing. OBPA is selected because it has a high level of antimicrobial activity, particularly when it is stabilized as taught herein. Phosphite stabilizers are selected because they can protect the microbial agent at the relatively high processing temperature used when fabricating nylon fibers. 
    
    
     Practice of the method inventions taught herein is described or self-evident from the preceding composition description and following examples. 
     EXAMPLES 1-6 
     Nylon 6 (polycaprolactam) chips were mixed with processing additives as defined below and with a concentrate of an antimicrobial agent previously prepared according to U.S. Pat. No. 4,086,297 (Rei) to achieve the blend compositions shown 
     
                       TABLE I______________________________________Example      1           2       3______________________________________Polycaprolactam(fiber grade)        99.95%      96.55%  93.45%OBPA         0.05        0.05    0.05Tinuvin 234  --          1.5     1.5Distearylthio-dipropionate --          0.4     0.4Irganox 1098 --          --      --Irganox B1171        --          --      --Irganox 1010 --          1.5     --Irganox B215 --          --      4.5Nickel dithio-carbamate    --          --      --Mineral oil  --          --      0.1______________________________________Example      4           5       6______________________________________Polycaprolactam(fiber grade 96.45%      94.95%  96.45%OBPA         0.05        0.05    0.05Tinuvin 234  1.5         1.5     1.5Distearylthio-dipropionate 0.4         0.4     0.4Irganox 1098 1.5         --      --Irganox B1171        --          3.0     --Irganox 1010 --          --      --Irganox B215 --          --      --Nickel dithio-carbamate    --          --      1.5Mineral Oil  0.1         0.1     0.1______________________________________ 
    
     (OBPA is added as a 5% active preparation containing 10,10&#39;-oxybisphenoxarsine dispersed in polycaprolactam, sold by Ventron Division of Morton Thiokol, Inc., Danvers, Mass.; the recited proportion is of pure OBPA. Tinuvin 234 is a trademark for an ultraviolet light absorber sold by Ciba-Geigy Corporation. Irganox is a trademark for antioxidants sold by Ciba-Geigy Corporation. The chemical identities of the Irganox materials have been identified previously.) 
     The blend compositions were each extruded into strands approximately 1/16 inch in diameter, cooled in a water bath, and immediately cut into pellets 1/8 inch long. These pellets were then melt-spun into nylon fibers according to techniques commonly known in the industry. The maximum processing temperature was about 285 degrees Celsius. 
     The fibers were subsequently evaluated for their biological activity by placing each one on a microbiological growth medium, solidified with agar, which had previously been innoculated with an actively growing culture of Staphylococcus aureus. 
     After incubating the media for 24 hours, the biological activity of each fiber sample was evaluated by measuring the width of the region around the fibers on the agar surface where no visible bacterial growth was evident. This width is defined as a Zone of Inhibition. Another evaluation of biological activity was made by extracting a specimen of each of the test samples with methanol. The extracted material was assayed by high performance liquid chromatography for recovery of the active antimicrobial agent. These results are tabulated in Table II. 
     
                       TABLE II______________________________________       Zone of     OBPAExample     Inhibition (mm)                   % recovered______________________________________1           3           112           5           593           7           524           6           695           5           596           5           58______________________________________ 
    
     It will be evident to those skilled in the art that the optimum treatment need not result in 100% recovery of OBPA, since it is added at a very low level and may be unavailable for analysis as the result of incomplete extraction. 
     These examples show that more undegraded OBPA remains in processed compositions 2-6 which also contain a stabilizing agent, and that the stabilized OBPA of Examples 2-6 is much more microbiocidally active than unstabilized OBPA of Example 1. (It should be understood that the Zone of Inhibition Test is conservative and understimates the advantage of employing an antioxidant.) 
     The advantages of the higher active level of an antimicrobial agent resulting from stabilization will be evident to those skilled in the art. For one thing the stabilized fibers can be subjected to a greater amount of post-finishing than unstabilized compositions without reducing the amount or potency of the antimicrobial agent in the fiber when it is put into use. 
     EXAMPLES 7-10 
     Unstabilized powdered polypropylene (sold under the trademark Profax 6301 PM by Hercules, Inc., Wilmington, Del.) was mixed with OBPA prepared according to U.S. Pat. No. 4,086,297 and processing additives as follows: 
     
                       TABLE III______________________________________Example       7      8         9    10______________________________________Polypropylene 99.95  98.70     97.95                               96.95(Profax 6301)OBPA          0.05   0.05      0.05 0.05Irganox 1010  --     1.0       1.0  1.0Distearylthio-dipropionate  --     0.25      --   --Tinuvin 770   --     --        1.0  2.0______________________________________ 
    
     The blends were converted into pellets by melt extrusion as in the previous examples. These pellets were melt-spun into polypropylene fibers according to techniques commonly known to the industry. 
     Microbiological effectiveness and active ingredient levels were obtained as in the previous examples and the results are presented in Table IV. 
     
                       TABLE IV______________________________________                      OBPAExample   Zone of Inhibition (mm))                      % Recovered______________________________________7         0                388         7                529         7                5910        6                58______________________________________ 
    
     Again, the fibers of Examples 8-10, which contain a stabilizer for the antimicrobial agent, contain more extractable antimicrobial agent and provide a much greater zone of inhibition than the fiber of Example 7 which contains no stabilizer. 
     EXAMPLE 11 
     In this example a polyvinyl chloride film composition containing stabilized OBPA is formed using conventional technology. 
     The formulation of the base film is: 
     
                       TABLE V______________________________________Component            Weight (g)______________________________________Polyvinyl chloride resin                100.00Di-2-ethylexyl phthalate (DOP)                40.00Epoxidized soybean oil                7.70UV Stabilizer (Mark 202 A)                1.00Heat Stabilizer (Mark KCB)                3.50Heat Stabilizer (Mark C)                1.50Stearic Acid         0.25OBPA concentrate*    .05______________________________________ *expressed as amount of pure OBPA   (&#34;Mark&#34; is a trademark for heat and light stabilizers sold by Argus Chemical Corp., Brooklyn, N.Y. DOP is a plasticizer, stearic acid is a lubricant, and epoxidized soybean oil is an antioxidant.) 
    
     Films are prepared by milling the components of the base until a uniform dispersion is obtained, at which time 0.05% by weight of carbon black is added. 
     The film is extrusion cast using conventional equipment at a processing temperature of 375 degrees Fahrenheit (191 degrees Celsius). The final film has a thickness of about 20 mils (500 microns). A control film is made in the same manner except that the stabilizer is omitted. The microbiocidal activity of the film is measured by cutting small round pieces of the test and control films, placing each one on an innoculated growth medium as described in Examples 1-6, and proceeding as described in those examples to develop and measure a Zone of Inhibition. The test samples are then extracted with methanol and the amount of recovered active ingredient is measured as described in Examples 1-6. Results comparable to those set forth in Examples 1-6 are obtained, illustrating that the invention can be used to improve antimicrobial films. 
     EXAMPLE 12 
     Examples 1 and 2 are repeated, except the OBPA is replaced in separate trials by each of the antimicrobial agents specified in the Background Art section of the present specification. The compositions analogous to Example 2 show much greater antimicrobial activity and a much greater recovery of the active antimicrobial agent than the corresponding compositions analogous to Example 1. This illustrates the applicability of the invention to each of the named antimicrobial agents. 
     EXAMPLE 13 
     Examples 1 and 2 are repeated, except the antioxidant (Irganox 1010) of Example 2 is replaced, in separate trials, by each of the antioxidants set forth in the Background Art section of the present specification. The compositions analogous to Example 2 show much greater antimicrobial activity and a much greater recovery of the active antimicrobial agent than the corresponding compositions analogous to Example 1. Thus, a wide range of antioxidants can be used to practice the invention. 
     EXAMPLE 14 
     Examples 1 and 2 are repeated, replacing polycaprolactam with each of the resins specified in the Background Art section of the present application in separate trials. Similar results are again obtained, and shown the value of the invention for improving the antimicrobial properties of many different resin compositions. 
     EXAMPLE 15 
     The following test composition was blended and formed into test fibers according to the procedure described in Examples 1-6: 
     
         ______________________________________Ingredient             Wt. %______________________________________polycaprolactam        98.96Irganox B1171          0.50Tinuvin T234           0.50OBPA                   0.04Total                  100.00______________________________________ 
    
     The fibers were then subjected to a modified continuous dyeing process adapted to simulate commercial continuous dyeing processes. The fibers were wet with a 0.1% by weight aqueous solution of a nonionic surfactant sold under the trademark Alrowet by Ciba-Geigy Corporation, Dyestuffs and Chemicals Division, Greensboro N.C.; followed by an aliquot of an aqueous solution adjusted to a pH value of 6.0 and containing 0.1% of the same surfactant and 2% of a dye sold under the trademark &#34;Tectilon Blue 4RKWL&#34; by Ciba-Geigy Corporation, Dyestuffs and Chemicals Division, Greensboro, N.C. The saturated fibers were steamed for 360 seconds at 101° C. and atmospheric pressure, followed by three rinses, each one liter of 40° C. tap water. 
     Fibers so treated were found to have retained all of their antimicrobial potency and 76% of their OBPA, as measured by high performance liquid chromatography. 
     EXAMPLE 16 
     Test fibers like those of Example 15 were used again here. A control composition lacking Irganox B1171 antioxidant but otherwise containing the same ingredients in the same proportions was processed in the same manner, then formed into control fibers. 
     The test and control fibers were then subjected to Beck mock-dyeing. Mock dye baths were prepared having a pH of 4.0 and containing 0.1% Triton X-100 surfactant in aqueous solution. In separate trials, 5% and 10% (based on the weight of the dye bath) of the test and control fibers were added to the boiling dye baths. The dye baths were boiled for up to 30 minutes. 
     The baths were then analyzed for arsenic content. The baths used to boil the control fibers contained about three times as much arsenic as the corresponding baths used to boil the test fibers containing an antioxidant. Thus, use of an antioxidant to preserve an antimicrobial agent in these fiber compositions reduces the loss of decomposition products of the antimicrobial agent into the dye bath, and thus into the dye effluent.