Hydrophilizing agent for hydrophobic porous membrane, and method for hydrophilizing hydrophobic porous membrane and test method using this agent

Abstract

A hydrophilizing agent for a hydrophobic porous membrane, wherein the agent contains a surfactant, and the surfactant has a frothability such that the bubble height immediately after frothing, as measured according to the Ross-Miles method (JIS K 3362), using a 0.1 wt % aqueous solution of the surfactant at 25° C., is 40 mm or less, and preferably has a frothability such that the bubble height five minutes after frothing is 20 mm or less; a method for hydrophilizing a hydrophobic porous membrane using this hydrophilizing agent; and a method for testing and hydrophilizing a membrane module using this hydrophilizing agent.

1 - 20 . (canceled) 
     
     
         21 . A hydrophobic porous membrane hydrophilized by a hydrophilizing agent, wherein the agent contains a surfactant, and the surfactant has a frothability such that the bubble height immediately after frothing, as measured according to the Ross-Miles method (JIS K 3362), using a 0.1 wt % aqueous solution of the surfactant at 25° C., is 40 mm or less. 
     
     
         22 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant has the frothability such that the bubble height immediately after frothing, as measured according to the Ross-Miles method (JIS K 3362), using a 0.1 wt % aqueous solution of the surfactant at 25° C., is 30 mm or less. 
     
     
         23 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant has a frothability such that the bubble height five minutes after frothing, as measured according to the Ross-Miles method (JIS K 3362), using a 0.1 wt % aqueous solution of the surfactant at 25° C., is 20 mm or less. 
     
     
         24 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 23 , wherein the surfactant has the frothability such that the bubble height five minutes after frothing is 15 mm or less. 
     
     
         25 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant has a static surface tension of 30 mN/m or less when a 0.1 wt % aqueous solution of the surfactant is used. 
     
     
         26 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 25 , wherein the surfactant has the static surface tension of 29 mN/m or less. 
     
     
         27 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant is a nonionic surfactant. 
     
     
         28 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant is acetylene glycol, ethoxylated acetylene glycol, or a mixture of these. 
     
     
         29 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant is selected from the group of 2,4,7,9-tetramethyl-5-decyn-4,7-diol, 3,6-dimethyl-4-octyn-3,6-diol, 3,5-dimethyl-1-hexyn-3-ol, 2,5,8,11-tetramethyl-6-dodecyn-5,8-diol, and ethoxylates of these. 
     
     
         30 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant is contained in an amount of 0.05 to 5 wt % with respect to the entire hydrophilizing agent. 
     
     
         31 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the agent further contains a solvent. 
     
     
         32 . The hydrophobic porous membrane according to  claim 31 , wherein the solvent is water. 
     
     
         33 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the hydrophobic porous membrane is formed from polyvinylidene fluoride. 
     
     
         34 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the hydrophobic porous membrane hydrophilized by a hydrophilizing agent is selected from the group consisting of a flat membrane, a hollow fiber membrane, a tubular membrane, and a spiral membrane. 
     
     
         35 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the hydrophobic porous membrane hydrophilized by a hydrophilizing agent has a plurality of pores having a pore diameter from 0.01 to 5 μm. 
     
     
         36 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the hydrophilization is conducted by bringing a unhydrophilized hydrophobic porous membrane into contact with the hydrophilizing agent. 
     
     
         37 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the adhesion proportion of the agent onto the hydrophobic porous membrane hydrophilized by a hydrophilizing agent is from 0.01 to 1.0 wt %. 
     
     
         38 . The hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 , wherein the surfactant has a static surface tension of 25 to 30 mN/m when a 0.1 wt % aqueous solution of the surfactant is used, wherein the surfactant is acetylene glycol, ethoxylated acetylene glycol, or a mixture of these, wherein the surfactant is contained in an amount of 0.05 to 1 wt % with respect to the entire hydrophilizing agent, wherein the hydrophobic porous membrane hydrophilized by a hydrophilizing agent is a hollow fiber membrane comprising a plurality of pores having a pore diameter from 0.1 to 1 μm. 
     
     
         39 . A membrane module comprising the hydrophobic porous membrane hydrophilized by a hydrophilizing agent according to  claim 21 . 
     
     
         40 . A membrane separation apparatus comprising a membrane module according to  claim 39 .