Process for making antimicrobial agents in aqueous dispersion form containing 2-(4- thiazolyl)-benzimidazole alone or in combination with 1,2-dibromo-2,4-dicyanobutane

Abstract

Aqueous dispersions of 2-(4-thiazolyl)-benzimidazole (TBZ), alone or in combination with 1,2-dibromo-2,4-dicyanobutane (DBDCB), and processes for making the same, are disclosed. These processes generally comprise mixing a xanthan gum with water, adding TBZ and mixing until uniform. DBDCB dispersions are prepared by mixing xanthan gum with water, adding DBDCB, maintaining the mixture at a temperature below about 40° C., grinding the mixture and mixing until uniform. The TBZ and DBDCB dispersions are then blended to prepare a dispersion containing both active ingredients. A method for inhibiting microbial growth utilizing these dispersions is also claimed.

What is claimed is:  
     
         1 . A process for preparing a 2-(4-thiazolyl)-benzimidazole (TBZ) antimicrobial composition in aqueous dispersion form comprising the steps of: 
 a. mixing an effective amount of xanthan gum with water in a vessel fitted with an agitator; and    b. adding an effective amount of TBZ to the mixture of step (a) and mixing until uniform.    
     
     
         2 . The process of  claim 1  which further comprises: 
 c. preparing a l,2-dibromo-2,4-dicyanobutane (DBDCB) antimicrobial composition in aqueous dispersion form by 
 i. mixing an effective amount of xanthan gum with water in a vessel fitted with an agitator;  
 ii. adding an effective amount of (DBDCB) to the mixture of step (i) and mixing until uniform;  
 iii. maintaining the mixture of step (ii) below a temperature of about 40+ C.;  
 iv. grinding the mixture of step (iii); and  
 
 d. mixing a desired quantity of the TBZ antimicrobial composition with a desired quantity of the DBDCB antimicrobial composition to form an admixture containing both DBDCB and TBZ in aqueous dispersion form.  
 
     
     
         3 . The process of  claim 2  wherein the steps of preparing the TBZ and DBDCB antimicrobial compositions in aqueous dispersion form further include adding effective amounts of one or more processing aids selected from the group consisting of sodium chloride, salts of ethylenediaminetetraacetic acid (EDTA), a block copolymer surfactant, an antifoam agent and a wetting agent.  
     
     
         4 . The process of  claim 2  wherein the step of preparing the DBDCB antimicrobial composition further comprises passing the ground mixture of step (iv) through a screen to remove lumps or gels.  
     
     
         5 . The process of  claim 1  wherein steps a) and b) result in a dispersion comprising: 
 a. between about 0.01 and 2% by weight xanthan gum;  
 b. between about 0.1 and 60% by weight TBZ; and the balance water.  
 
     
     
         6 . The process of  claim 2  wherein steps a), b) and c) result in a dispersion comprising: 
 a. between about 0.01 and 2% by weight xanthan gum;  
 b. between about 0.1 and 60% by weight TBZ;  
 c. between about 0.1 and 60% by weight DBDCB; and the balance water.  
 
     
     
         7 . An aqueous dispersion useful as an antimicrobial agent comprising an effective amount of 2-(4-thiazolyl)-benzimidazole (TBZ) as an active ingredient and an effective amount of xanthan gum as a stabilizer.  
     
     
         8 . The dispersion of  claim 7  wherein the TBZ is present in a concentration ranging between about 0.1% and 60% by weight.  
     
     
         9 . The dispersion of  claim 7  wherein the TBZ is present in a concentration ranging between about 20% and 30% by weight.  
     
     
         10 . The dispersion of  claim 7  further comprising an effective amount of 1,2-dibromo-2,4-dicyanobutane (DBDCB) as an active ingredient.  
     
     
         11 . The dispersion of  claim 10  wherein the total concentration of DBDCB and TBZ active ingredients ranges from about 0.1% to 60%.  
     
     
         12 . The dispersion of  claim 10  wherein the total concentration of DBDCB and TBZ active ingredients ranges from about 20% to 30%.  
     
     
         13 . The dispersion of  claim 10  wherein the weight ratio, on an active basis, of DBDCB to TBZ is between about 4:1 and 1:4.  
     
     
         14 . The dispersion of  claim 10  comprising: 
 a. between about 0.01 and 2% by weight xanthan gum;  
 b. between about 0.1 and 60% by weight TBZ;  
 c. between about 0.1 and 60% by weight DBDCB; and the balance water.  
 
     
     
         15 . The dispersion of  claim 10  further comprising effective amounts of one or more processing aids selected from the group consisting of sodium chloride, salts of ethylenediaminetetraacetic acid (EDTA), a block copolymer surfactant, an antifoam agent and a wetting agent.  
     
     
         16 . A process for preparing an aqueous dispersion of 1,2-dibromo-2,4-dicyanobutane (DBDCB) and 2-(4-thiazolyl)-benzimidazole (TBZ) comprising the steps of: 
 a. mixing an effective amount of xanthan gum with water in a vessel fitted with an agitator;    b. adding an effective amount of DBDCB to the mixture of step (a) and mixing until uniform;    c. maintaining the mixture of step (b) below a temperature of about 40° C.;    d. grinding the mixture of step (c);    e. adding an effective amount of TBZ to the ground mixture of step (d); and    f. mixing until uniform.    
     
     
         17 . The process of  claim 16  which further comprises: adding an effective amount of both DBDCB and TBZ to the mixture of step (a), and wherein step (e) is eliminated.  
     
     
         18 . The process of  claim 16  wherein steps a) through f) result in a composition comprising: 
 a. between about 0.01 and 2% by weight xanthan gum;  
 b. between about 0.1 and 60% by weight TBZ;  
 c. between about 0.1 and 60% by weight DBDCB; and the balance water.  
 
     
     
         19 . A process for preparing an aqueous dispersion of 1,2-dibromo-2,4-dicyanobutane (DBDCB) and 2-(4-thiazolyl)-benzimidazole (TBZ) which process comprises: 
 a. mixing water and effective amounts of sodium chloride, a salt form of ethylenediaminetetraacetic acid, and a surfactant in a vessel fitted with and agitator;    b. adding an effective amount of food grade, enzyme free xanthan gum to the mixture of step (a);    c. adding an effective amount of an antifoam emulsion to the mixture of step (b) and mixing until uniform;    d. adding an effective amount of DBDCB to the mixture of step (c) and mixing until uniform;    e. cooling the mixture of step (d) to a temperature of about 25° C.;    f. grinding the mixture of step (e);    g. passing the ground mixture through a screen to remove gels or lumps;    h. adding an effective amount of TBZ to the ground mixture of step (g); and    i. mixing until uniform.    
     
     
         20 . The process of  claim 19  which further comprises: adding an effective amount of both DBDCB and TBZ to the mixture of step (c), and wherein step (h) is eliminated.  
     
     
         21 . A method of inhibiting microbial growth comprising contacting said growth with an effective amount of an admixture comprising 1,2-dibromo-2,4-dicyanobutane and 2-(4-thiazolyl)-benzimidazole prepared by the process comprising the steps of: 
 a. mixing an effective amount of xanthan gum with water in a vessel fitted with an agitator;    b. adding an effective amount of DBDCB to the mixture of step (a) and mixing until uniform;    c. maintaining the mixture of step (b) below a temperature of about 40° C.;    d. grinding the mixture of step (c);    e. adding an effective amount of TBZ to the ground mixture of step (d); and    f. mixing until uniform.    
     
     
         22 . The method of  claim 21  which further comprises adding an effective amount of both DBDCB and TBZ to the mixture of step (a), and wherein step (e) is eliminated.  
     
     
         23 . The method of  claim 21  wherein the total concentration of DBDCB and TBZ active ingredients ranges from about 0.1% to 60%.  
     
     
         24 . The method of  claim 21  wherein the total concentration of DBDCB and TBZ active ingredients ranges from about 20% to 30%.  
     
     
         25 . The method of  claim 21  in which the ratio of DBDCB to TBZ is about 4:1.  
     
     
         26 . The method of  claim 21  wherein said admixture comprises: 
 a. between about 0.01 and 2% by weight xanthan gum;  
 b. between about 0.1 and 60% by weight TBZ;  
 c. between about 0.1 and 60% by weight DBDCB; and the balance water.