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:
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 clamed 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 or2,6-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______________________________________TRADENAME          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 antioxidantused in rubber and latex.______________________________________TRADENAME             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. 2- and 3-t-Butyl-4-hydroxyanisole or2- 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 antioxidantfrequently used in foods.______________________________________TRADENAME             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.                          SPECIFICTRADENAME        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 AO-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 49-454            Reichhold     1.32Stabilite White Liquid 49-455            Reichhold     0.91Stabilite 49-470 (2)            ReichholdStabiwhite Powder            CP 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.______________________________________TRADENAME          SUPPLIER______________________________________Ethyl Antioxidant 754              Ethyl______________________________________6. `Fortified` hindered phenol(Structured not disclosed)              White powder              Melt Point 95° C. min.              Specific Gravity 1.30General purpose phenolic antioxidant used in compoundingwhere color and staining are critical.______________________________________TRADENAME          SUPPLIER______________________________________Vanox ZS           Vanderbilt______________________________________7. 2,6-Di-t-butyl-4-sec-butylphenol ##STR9##          Mole Weight 262 Amber liquid Specific Gravity______________________________________              0.90TRADENAME          SUPPLIER______________________________________Isonox 132         SchenectadyVanox 1320         Vanderbilt______________________________________ 
    
     
         __________________________________________________________________________BISPHENOLS AND THIOBISPHENOLS__________________________________________________________________________1. 2,2&#39;-Methylenebis(6-t-butyl-p-cresol) or2,2&#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 and plastics.Essentially non-staining, but can cause slight pink discoloration.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 119-125° C. Specific Gravity 1.10General purpose antioxidant weaker than (B-1), but less discoloring.TRADE NAME             SUPPLIER__________________________________________________________________________Cyanox 425             Cyanamid__________________________________________________________________________3. 4,4&#39;-Methylenebis(2,6-di-t-butylphenol) ##STR12##                Mole Weight 424 Light yellow crystalline powder                     elt 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 form`- 
    
     
         4. Miscellaneous bisphenols - structures not revealed                 SPECIFICTRADE NAME    PHYS FORM                 GRAVITY    SUPPLIER__________________________________________________________________________Cyanox 53 (1) White powder                 1.74       CyanamidNaugawhite    Amber liquid                 0.96       UniroyalNaugawhite Powder (1)         Tan powder                 1.19       UniroyalPermanax WSO  White powder                 1.00       VulnaxWytox PAP     Amber liquid                 0.92       OlinWytox PSP-S (1)         Tan powder         OlinWytox PAP-SE (2)         Amber liquid                 0.92       Olin__________________________________________________________________________ (1) `On an inert carrier`- (2) Self emulsifiable form 
    
     
         5. 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) or4,4&#39;-Butylidenebis(6-t-butyl-3-methylphenol) ##STR15##                Mole Weight 382.5 White powder Melt Point                     209° C. Specific Gravity 1.03Antioxidant for rubber, latex and plastics compounding.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 polymer stabilization.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) or4,4&#39;-Thiobis(6-t-butyl-3-metyhylphenol) ##STR16##                Mole Weight 358.5 Light colored powder Melt                     Point 150° C. Specific Gravity                     1.06-1.12Antioxidant for rubber, latex and plastics compounding. Widely used inCR.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 (2) More pure form of Santowhite (3) Reaction product grade 
    
     
         10. 4,4&#39;-Methylenebis(2,6-dimethylphenol) ##STR17##                Mole Weight 256TRADE 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 1.02TRADE NAME             SUPPLIER__________________________________________________________________________Ethyl Antioxidant 738  Ethyl__________________________________________________________________________13. 2,2&#39;-Thiobis(4-methyl-6-t-butylphenol) ##STR19##                Mole Weight 359TRADE NAME PHYS FORM    MELT 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 190-194° C.TRADE NAME             SUPPLIER__________________________________________________________________________SAO-44                 Southland__________________________________________________________________________15. 2.2&#39;-Isobutylidenebis(4,6-dimethylphenol) ##STR20##                Mole Weight 298 White powder Specific Gravity                     1.12TRADE 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 1.08TRADE NAME             SUPPLIER__________________________________________________________________________Vulkanox ZKF           Mobay__________________________________________________________________________ 
    
     
         ______________________________________POLYPHENOLS______________________________________1. 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 temperatureapplications. Especially recommended for NR, IR, SBR,CR and carboxylated polymers. Widely used in latex.TRADE NAME           SUPPLIER______________________________________WINGSTAY L Flake     GOODYEARWINGSTAY L Powder    GOODYEAR______________________________________2. 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 1.45TRADE NAME           SUPPLIER______________________________________Irganox 1010         CIBA-GEIGY______________________________________3. 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, resinsand waxes.TRADE NAME           SUPPLIER______________________________________Ethyl Antioxidant 330                Ethyl______________________________________4. 1,3,5-Tris(3,5-di-t-butyl-4-hydroxybenzyl)-s-triazine-2,4,6(1H,3H,5H)trione or 1,3,5-Tris(3,5-di-t-butyl-4-hydroxy-benzyl) isocyanurate ##STR25##           White crystalline powder           Melt Point 217-225° C.           Specific Gravity 1.03High temperature antioxidant recommended for plastics.TRADE NAME           SUPPLIER______________________________________Agerite GT           VanderbiltGood-rite 3114       GoodrichVanox GT             Vanderbilt______________________________________5. 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______________________________________6. Phenolic condensation products with structures not revealed.General purpose antioxidants for rubber and plasticscompounding.                   SPECIFICTRADE NAME PHYS FORM    GRAVITY   SUPPLIER______________________________________Akrochem   White powder 1.04      AkronAntiox 33  (M P 100° C.    Chemical      Min.)Akrochem   White powder 1.05      AkronAntiox 36  (M P 148° C.)   ChemicalAkrochem   White powder 1.04      AkronAntiox 51  (M P 118° C.)   ChemicalLowinox 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 (M P  1.04      Reichhold      110--110° C.)Stabilite 49-467      Powder       1.05      Reichhold      (M P 148° C.)Wytox PDA-S      Tan powder -           Olin      contains inert      carrierWytox PMW  Amber powder 1.05-1.07 Olin      (M P 122° C.)______________________________________7. 4-((4,6-Bis(octylthio)-2-triazin-2-yl)amino)-2,6-di-t-butylphenol or2,4-(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 shortshop; 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 shortshop.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______________________________________1. 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      InterstabLowinox TNPP         LowiMark 1178            ArgusMark 1178B (1)       ArgusNaugard P            UniroyalNaugard PHR (1)      UniroyalPolygard             UniroyalPolygard HR (1)      UniroyalWeston TNPP          Borg-WarnerWeston 399 (2)       Borg-WarnerWeston 399B (2)      Borg-WarnerWytox 312            OlinWytox 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______________________________________3. 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-WarnerWeston 619 (1)       Borg-Warner______________________________________ (1) More hydrolytically stable grade, containing TIPA 
    
     
         4. `Polymeric` phosphites-structures not disclosedGeneral purpose antioxidants andstabilizers 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 phenolic antioxidant 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(E3) and tetrakis(methylen 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.           White powder           Specific Gravity 1.04, 1.76 (1)Antioxidant systems for polyolefins.TRADE NAME           SUPPLIER______________________________________Vanox 1030           VanderbiltVanox 1040 (1)       Vanderbilt______________________________________ (1) Contains a mineral deactivator for mineral filled compounds. 
    
     
         __________________________________________________________________________MULTIFUNCTIONAL NON-STAINING ANTIOXIDANTS__________________________________________________________________________1. O,ODi-n-octadecyl(3,5-di-t-butyl-4-hydroxybenzyl)phosphonate ##STR38##                                   Mole Weight 805 White                                        crystalline powder Melt                                        Point 45° C. Min.                                        Specific Gravity 0.96Antioxidant, stabilizer for plastics.TRADE NAME                                   SUPPLIER__________________________________________________________________________Irganox 1093                                 CIBA-GEIGY__________________________________________________________________________2. 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 639 Off-white                                        crystalline powder Melt                                        Point 94-108° C.General purpose antioxidant for plastics and elastomers.TRADE NAME                                   SUPPLIER__________________________________________________________________________Irganox 259                                  CIBA-GEIGY__________________________________________________________________________3. Thiodiethylene bis(3,5-di-t-butyl-4-hydroxy)hydrocinnamate orThiodiethylene bis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate) ##STR40##                                   Mole Weight 642 White                                        crystalline powder Melt                                        Point 63° C. Min.                                        Specific Gravity 1.19Antioxidant for plastic and elastomers.TRADE NAME                                   SUPPLIER__________________________________________________________________________Irganox 1035                                 CIBA-GEIGY__________________________________________________________________________4. Octadecyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate orOctadecyl 3,5-di-t-butyl-4-hydroxyhydrocinnamate ##STR41##                                   Mole Weight 531 White                                        crystalline powder Specific                                        Gravity 1.02 Melt Point                                        49-54° C.Antioxidants for plastics and elastomers.TRADE NAME                                   SUPPLIER__________________________________________________________________________Irganox 1076                                 CIBA-GEIGY__________________________________________________________________________5. 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 637 White                                        crystalline powder Specific                                        Gravity 1.05 Melt Point                                        156-162° C.Antioxidants for polyamides, plastics and elastomers.TRADE NAME                                   SUPPLIER__________________________________________________________________________Irganox 1098                                 CIBA-GEIGY__________________________________________________________________________6. 3,5-Di-t-butyl-4-hydroxyhydrocinnamic acid triester with1,3,5-Tris(2-hydroxyethyl)-s-triazine-2,4,6-(1H,3H,5H)trione ##STR43##                                  ##STR44##                                        Mole Weight 1042                                        White crystalline powder                                        Specific Gravity 0.921                                        Melt Point 123-131°                                        C.Antioxidant for plastics.TRADE NAME                                   SUPPLIER__________________________________________________________________________Good-rite 3125                               GoodrichAgerite SKT, Vanox SKT                       Vanderbilt__________________________________________________________________________7. NButyryl-p-aminophenol or N(4-Hydroxyphenyl)butyramide ##STR45##                                   Mole Weight 179 White powder                                        elt Point 136-141°                                        C.Antioxidants for plastics and elastomers.TRADE NAME                                   SUPPLIER__________________________________________________________________________Suconox 4                                    Hexel__________________________________________________________________________8. NPelargonoyl-p-aminophenol or N(4-Hydroxyphenyl)pelargonamide ##STR46##                                   Mole Weight 249 White powder                                        elt Point 121-125°                                        C.Antioxidant for plastics and elastomers.TRADE NAME                                   SUPPLIER__________________________________________________________________________Suconox 9                                    Hexel__________________________________________________________________________9. NLauroyl-p-aminophenol or N(4-Hydroxyphenyl)dodecanamide ##STR47##                                   Mole Weight 291 White powder                                         Melt 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 376 White powder                                        elt Point 130-134°                                        C.Antioxidant for polyethylene and polyamides.TRADE NAME                                   SUPPLIER__________________________________________________________________________Suconox 18                                   Hexel__________________________________________________________________________11. 2,6-Di-t-butyl-alpha-dimethylamino-p-cresol or2,6-Di-t-butyl-4-(dimethylaminomethyl)phenol ##STR49##                                   Mole Weight 263 Light yellow                                        crystalline powder Melt                                        Point 94° C.Antioxidant for plastics and elastomers.TRADE NAME                                   SUPPLIER__________________________________________________________________________Ethyl Antioxidant 703                        Ethyl__________________________________________________________________________12. 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 699                                        Off-white powder                                        Melt Point 145-155°                                        C.TRADE NAME                                   SUPPLIER__________________________________________________________________________Cyanox 1790                                  Cyanamid__________________________________________________________________________13. Nickel bis(Oethyl(3,5-di-t-butyl-4-hydroxybenzyl)phosphonate) ##STR52##                                   Mole Weight 714 Tan-light                                        green powder Melt Point                                        180° C. Min.Antioxidant/UV absorber for plastics.TRADE NAME                                   SUPPLIER__________________________________________________________________________Irgastab 2002                                CIBA-GEIGY__________________________________________________________________________14. 2,2&#39;-Oxamidobisethyl 3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate ##STR53##                                   Mole Weight 697 Off-white                                        powder Melt Point                                        173° C.Antioxidant and metal deactivator.TRADE NAME                                   SUPPLIER__________________________________________________________________________Naugard XL-1                                 Uniroyal__________________________________________________________________________15. Phenolic antioxidant/metal deactivator - undisclosed composition.    SPECIFICTRADE NAME    GRAVITY               MELT POINT                                  SUPPLIER__________________________________________________________________________Irganox MD-1024    1.12                  224° C. Min.                                  CIBA-GEIGY__________________________________________________________________________16. Tris(2-t-butyl-4-(2-methyl-4-hydroxy-5-t-butylphenylthio)-5-methyl)phenylphosphite ##STR54##                                   Mole Weight 1103Antioxidant and metal deactivator                             SPECIFICTRADE NAME PHYS FORM              GRAVITY                                   SUPPLIER__________________________________________________________________________Antioxidant VP OSP 1      White powder           1.10  Hoechst__________________________________________________________________________17. Bis(3,3-bis(4-hydroxy-3-t-butylphenyl)butanoic acid)glycolester                                        Mole Weight 795                                        Melt Point 170° C.                            SPECIFICTRADE NAME    PHYS FORM               GRAVITY                                  SUPPLIER__________________________________________________________________________Hostanox 03    White powder            1.1   Hoechst__________________________________________________________________________18. 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__________________________________________________________________________19. n-Propyl gallate or n-Propyl 3,4,5-tri-hydroxybenzoate ##STR56##                                   Mole Weight 212  White                                        powder Melt 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 647 Off-white                                        powder Melt Point                                        &gt;260° C.Antioxidant/metal deactivatorTRADE NAME                                   SUPPLIER__________________________________________________________________________Irganox 1425                                 CIBA-GEIGY__________________________________________________________________________21. 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 164 Yellow-white powder Specific Gravity               1.25 Melt Point 270° C.and ##STR59##Antioxidant, synergist and metal deactivator.TRADE NAME          SUPPLIER______________________________________Vulkanox MB-2/MG    Mobay______________________________________2. Zinc salt of 2-mercaptobenzimidazole ##STR60##          White powder Specific Gravity 1.75 Melt 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 ##STR61##       SPECIFICTRADE NAME  GRAVITY   MELT 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 ##STR62##          Mole Weight 164 Melt 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 ##STR63##           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 disulfide H.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@55° C.                             Hoechst______________________________________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      Vulnaz       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 ##STR64##         Mole Weight 219 Tan-purple powder Melt point              50-59° C. Specific Gravity 1.16-1.20TRADE NAME         SUPPLIER______________________________________Additin 30         MobayAkrochem Antioxidant PANA              Akron ChemicalNaugard PAN        Uniroyal______________________________________2. NPhenyl-beta-naphthylamine (Commonly called `PBNA`) ##STR65##         Mole Weight 219 Dark Solid Melt Point 105-106°              C. Specific Gravity 1.18-1.24Powerful staining antioxidant exstensively used in Europe.No known suppliers in the USA.______________________________________ 
    
     
         __________________________________________________________________________DIPHENYLAMINE AND OTHER DIARYLAMINE DERIVATIVES__________________________________________________________________________1. p-Oriented styrenated diphenylamine ##STR66##Mostly 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         GOODYEAR  WINGSTAY 29 Powder (1)                      GOODYEAR  Lowinox SDA (2)     Lowi  Vulkanox 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 ##STR67##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 ##STR68##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 microcel (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             Uniroyal   Naugard BG        Uniroyal   Vanox 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 ##STR69##Powerful 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 ##STR70##Powerful 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 ##STR71##Antioxidant-antiozonant.   TRADE NAME        SUPPLIER__________________________________________________________________________   UOP 688           UOP__________________________________________________________________________4. NPhenyl-N&#39;cyclohexyl-p-phenylenediamine ##STR72##Antioxidant-antiozonant.   TRADE NAME        SUPPLIER__________________________________________________________________________   Flexzone 6H       Uniroyal__________________________________________________________________________5. Mixed diaryl-p-phenylenediamines ##STR73##Persistent antioxidants, antiozonants and antiflex agents for manynatural and syntheticrubber compounds. Very powerful antiozonants for CR. Very non-volatileand slow toextract.      PHYSICAL MELT  SPECIFICTRADE NAME FORM     POINT GRAVITY                            SUPPLIER__________________________________________________________________________WINGSTAY 100      Silver-gray flakes               90-105° C.                     1.18   GOODYEARWINGSTAY 100AZ      Gray flakes               110° C.                     1.18   GOODYEAR(1)WINGSTAY 200      Low-melting               60° C.                     1.18   GOODYEAR      semi-solid__________________________________________________________________________ (1) Special low scorch grade for neoprene (CR)6. N,N&#39;Diphenyl-p-phenylenediamine ##STR74##General purpose antioxidant and flex crack inhibitor. Limited solubilityin most polymers.   TRADE NAME        SUPPLIER__________________________________________________________________________   Agerite DPPD      Vanderbilt   J-Z-F             Uniroyal   Naugard J         Uniroyal   Permanax DPPD     Vulnax__________________________________________________________________________7. N,N&#39;Di-beta-naphthyl-p-phenylenediamine ##STR75##Antioxidant and metal deactivator. Not an antiozonant.  TRADE NAME          SUPPLIER__________________________________________________________________________  Agerite White       Vanderbilt  Agerite White White (1)                      Vanderbilt__________________________________________________________________________ (1) Special grade 
    
     
         8. N,N&#39;Bis(1,4-dimethylpentyl)-p-phenylenediamine ##STR76##General purpose antiozonant. Activates cure systems.   TRADE NAME        SUPPLIER__________________________________________________________________________   Flexzone 4L       Uniroyal   Santoflex 77      Monsanto   UOP 788           UOP__________________________________________________________________________9. N,N&#39;Bis(1-ethyl-3-methylpentyl)-p-phenylenediamine ##STR77##General purpose antiozonant. Activates cure systems.   TRADE NAME        SUPPLIER__________________________________________________________________________   Antozite 2        Vanderbilt   Flexzone 8L       Uniroyal   UOP 88            UOP__________________________________________________________________________10. N,N&#39;Bis(1-methylheptyl)-p-phenylenediamine ##STR78##General purpose antiozonant. Activates cure systems.   TRADE NAME        SUPPLIER__________________________________________________________________________   Antozite 1        Vanderbilt   Santoflex 217     Monsanto   UOP 288           UOP__________________________________________________________________________11. NPhenyl-N&#39;-(p-toluenesulfonyl)-p-phenylenediamine ##STR79##Semi-discoloring antioxidant and copper inhibitor.   TRADE NAME        SUPPLIER__________________________________________________________________________   Aranox            Uniroyal__________________________________________________________________________ 
    
     
         ______________________________________QUINOLINES______________________________________1. Polymerized 2,2,4-trimethyl-1,2-dihydroquinoline ##STR80##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 ##STR81##General 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 ##STR82##Highly 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 productof 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 and35% 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, UOP 588 and UOP 688 
    
     
         5. Blend of 50% N,N&#39;--bis(1,4-dimethylpentyl)-p-phenylenediamine(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 bean antiozonant.                   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 amineantioxidant                   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 ##STR83##Antiozonant for SBR and NBR antioxidant for several specialty 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 ##STR84##Antiozonant for SBR and NBR; antioxidant for several specialty polymers.                   SPECIFICTRADE NAME  PHYS FORM   GRAVITY   SUPPLIER______________________________________Isobutyl Niclate       Green powder                   1.27      Vanderbilt______________________________________3. Nickel dimethyldithiocarbamate ##STR85##Specialty 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______________________________________AkrochemAntiozonant E-9604       Gray powder 1.74      Akron                             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, Ohio. 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 contemplated 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-butylpheyl)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, optionally 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 percent (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        99.95%     96.55%   93.45%(fiber grade)OBPA         0.05       0.05     0.05Tinuvin 234  --         1.5      1.5Distearylthio-        --         0.4      0.4dipropionateIrganox 1098 --         --       --Irganox B1171        --         --       --Irganox 1010 --         1.5      --Irganox B215 --         --       4.5Nickel dithio-        --         --       --carbamateMineral oil  --         --       0.1______________________________________Example      4          5        6______________________________________Polycaprolactam        96.45%     94.95%   96.45%(fiber grade)OBPA         0.05       0.05     0.05Tinuvin 234  1.5        1.5      1.5Distearylthio-        0.4        0.4      0.4dipropionateIrganox 1098 1.5        --       --Irganox B1171        --         3.0      --Irganox 1010 --         --       --Irganox B215 --         --       --Nickel dithio-        --         --       1.5carbamateMineral Oil  0.1        0.1      0.1______________________________________ 
    
     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 underestimates 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-        --     0.25        --   --dipropionateTinuvin 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 202A)                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, New York. 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 show 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.