Method of sulfonating an article and related apparatus

Abstract

An article is sulfonated by forming a sulfonating gas composition containing a gaseous sulfur-containing compound provided from a gas source. The gas source may utilize a chemical feed stock that includes a precursor sulfur-containing compound. The article is then contacted with the sulfur-containing gas until a surface treatment is effected. Next, the article is then optionally contacted with a gaseous neutralization composition, and then a liquid neutralization composition. In another sulfonation method, a first test sample is sulfonated and then analyzed by inductively coupled plasma analysis and X-ray fluorescence spectroscopy. A calibration relationship between the two spectroscopic techniques is determined with the inductively coupled plasma atomic spectroscopic value taken as the accurate value. In subsequent sulfonation runs, test samples are included and monitored by X-ray fluorescence.

1 . A method of sulfonating the surface of a resin-containing article, the method comprising:
 a) forming a sulfonating gas composition, the sulfonating gas composition comprising a sulfur-containing gaseous compound provided from a gas source;   b) contacting the article with the sulfonating gas composition, the surface having an acid residue concentration formed thereon; and   c) contacting the article with a liquid neutralization composition at a sufficient temperature to adjust the acid residue concentration such that the article has a surface pH greater than or equal to 3.   
   
   
       2 . The method of  claim 1  further comprising contacting the article with a gaseous neutralization composition prior to step c). 
   
   
       3 . The method of  claim 1  wherein step is performed at a temperature from about 40° C. to about 90° C. 
   
   
       4 . The method of  claim 1  wherein the gas source utilizes a chemical feed stock selected from the group consisting of raw sulfur, processed sulfur, sulfur dioxide, liquid sulfur dioxide, sulfur trioxide, sulfuric acid and mixtures thereof. 
   
   
       5 . The method of  claim 1  wherein the article is placed in a reaction chamber prior to step b). 
   
   
       6 . The method of  claim 5  wherein after step b) the sulfonating gas is removed from the reaction chamber. 
   
   
       7 . The method of  claim 1  wherein prior to step c) the article is transferred to a neutralization chamber. 
   
   
       8 . The method of  claim 1  wherein the sulfonating gas composition further comprises substantially dry air. 
   
   
       9 . The method of  claim 1  wherein the gaseous neutralization composition comprises ammonia. 
   
   
       10 . The method of  claim 1  wherein the liquid neutralization composition comprises a base. 
   
   
       11 . The method of  claim 10  wherein the liquid neutralization composition comprises caustic soda. 
   
   
       12 . The method of  claim 10  wherein the base is selected from the group consisting of aqueous ammonia, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and combinations thereof. 
   
   
       13 . The method of  claim 10  wherein the liquid neutralization composition is heated during or prior to step c). 
   
   
       14 . The method of  claim 1  wherein the gas source is an on-site gas generator which oxidizes sulfur dioxide into sulfur trioxide. 
   
   
       15 . The method of  claim 1  wherein the gas source is an on-site gas generator in which sulfur is burned to form sulfur dioxide followed by oxidization of the sulfur dioxide into sulfur trioxide. 
   
   
       16 . The method of  claim 15  wherein the step of forming a sulfonating gas composition comprising transferring a sulfuric acid-containing composition into a vaporizer and then mixing with air. 
   
   
       17 . The method of  claim 1  wherein the article is an enclosed vessel into which the sulfonating gas is introduced such that the interior of the vessel is sulfonated.