Electrodeposition process

Abstract

The present invention is directed to an electrodeposition process for producing a coated substrate having improved properties. The electrodeposition process comprises coating a substrate with a liquid coating composition, immersing the substrate with the liquid coating composition in an electrodeposition bath, and applying an electrical current having a specified voltage to form an electrodeposition coating to the substrate. In a preferred embodiment, the electrical current is applied prior to immersing the coated substrate in the bath. The coating can further be etched to beneficially texture the surface of the coated substrate. The substrate coated with the process of the invention exhibits improved corrosion resistance, durability, lubricity, adhesion, as well as other favorable characteristics.

1 . An electrodeposition process comprising: 
 coating a substrate with a liquid coating composition;    immersing the coated substrate in a bath comprising a material for electrodeposition; and    applying for a period of time an electrical current having a specified voltage to form an electrodeposition coating on the substrate.    
   
   
       2 . The electrodeposition process according to  claim 1 , further comprising reducing the voltage of the electrical current after said applying step, and then applying an electrical current for a second period of time to form a final electrodeposition coating of a desired thickness.  
   
   
       3 . The electrodeposition process according to  claim 2 , further comprising adjusting the electrical current during the second period of time.  
   
   
       4 . The electrodeposition process according to  claim 1 , further comprising roughing a surface of the substrate prior to said step of coating the substrate with a liquid coating composition.  
   
   
       5 . The electrodeposition process according to  claim 1 , further comprising curing the liquid coating composition prior to said immersing step.  
   
   
       6 . The electrodeposition process according to  claim 1 , wherein said step of applying an electrical current takes place prior to said immersing step.  
   
   
       7 . The electrodeposition process according to  claim 6 , wherein the electrical current is applied to the coated substrate or to the bath.  
   
   
       8 . The electrodeposition process according to  claim 1 , wherein the liquid coating composition comprises a material selected from the group consisting of polymeric materials, polar liquids, non-polar liquids, surface tension-modifying compounds, antioxidants, organic liquids, petroleum-based substances, waxes, buffering materials, particulate suspensions, colloidal materials, resins, and mixtures thereof.  
   
   
       9 . The electrodeposition process according to  claim 1 , wherein the liquid coating composition comprises a lower alkyl carboxylic acid moiety.  
   
   
       10 . The electrodeposition process according to  claim 9 , wherein the lower alkyl carboxylic acid moiety is derived from a C 1  to C 6  carboxylic acid, salt, or derivative thereof.  
   
   
       11 . The electrodeposition process according to  claim 9 , wherein the lower alkyl carboxylic acid moiety is derived from a C 1  to C 6  carboxylate.  
   
   
       12 . The electrodeposition process according to  claim 11 , wherein the carboxylate is selected from the group consisting of formate, acetate, propionate, butyrate, 2-methyl propionate, and mixtures thereof.  
   
   
       13 . The electrodeposition process according to  claim 9 , wherein the lower alkyl carboxylic acid moiety is derived from sodium propionate.  
   
   
       14 . The electrodeposition process according to  claim 9 , wherein the liquid coating composition further comprises at least one moiety selected from the group consisting of a 2,4-trans, trans-hexadienoic moiety, a benzoic moiety, a phosphate moiety, a citrate moiety, acids and salts thereof, and mixtures thereof.  
   
   
       15 . The electrodeposition process according to  claim 1 , wherein the liquid coating composition comprises an electrically conductive material.  
   
   
       16 . The electrodeposition process according to  claim 1 , wherein the liquid coating composition comprises a positive charge.  
   
   
       17 . The electrodeposition process according to  claim 1 , wherein the material for electrodeposition comprises a metal.  
   
   
       18 . The electrodeposition process according to  claim 17 , wherein the metal comprises a transition metal.  
   
   
       19 . The electrodeposition process according to  claim 1 , wherein the material for electrodeposition comprises a conductive polymer.  
   
   
       20 . The electrodeposition process according to  claim 1 , wherein the bath further comprises one or more additive.  
   
   
       21 . The electrodeposition process according to  claim 20 , wherein the one or more additive is selected from the group consisting of anticorrosive agents, brighteners, wetting agents, adhesion improvers, and pH buffers.  
   
   
       22 . The electrodeposition process according to  claim 1 , wherein the substrate comprises a metal.  
   
   
       23 . The electrodeposition process according to  claim 1 , wherein the substrate comprises a conductive polymer.  
   
   
       24 . The electrodeposition process according to  claim 1 , wherein the period of time is a period of about 0.1 second to about 3 hours.  
   
   
       25 . The electrodeposition process according to  claim 24 , wherein the period of time is a period of about 1 second to about 30 minutes.  
   
   
       26 . The electrodeposition process according to  claim 24 , wherein the period of time is a period of about 5 seconds to about 2 minutes.  
   
   
       27 . The electrodeposition process according to  claim 1 , wherein the current creates a voltage of about 1 mV to about 500 V.  
   
   
       28 . The electrodeposition process according to  claim 1 , wherein the electrodeposition coating has a thickness of at least about 0.1 micron.  
   
   
       29 . The electrodeposition process according to  claim 1 , wherein the electrodeposition coating has a uniform thickness on the substrate.  
   
   
       30 . The electrodeposition process according to  claim 2 , wherein the voltage of the electrical current is reduced by at least 30%.  
   
   
       31 . The electrodeposition process according to  claim 30 , wherein the voltage of the electrical current is reduced by at least 50%.  
   
   
       32 . The electrodeposition process according to  claim 30 , wherein the voltage of the electrical current is reduced by at least 70%.  
   
   
       33 . An electrodeposition process comprising: 
 coating a substrate with a liquid coating composition;    immersing the coated substrate in a bath comprising a material for electrodeposition;    applying for a first period of time an electrical current of specified voltage having a beginning polarity to form an initial electrodeposition coating on the substrate;    reducing the voltage of the electrical current;    applying an electrical current for a second period of time to form a final electrodeposition coating of a desired thickness; and    etching the final electrodeposition coating.    
   
   
       34 . The electrodeposition process according to  claim 33 , further comprising adjusting the electrical current during the second period of time.  
   
   
       35 . The electrodeposition process according to  claim 33 , further comprising roughing a surface of the substrate prior to said step of coating the substrate with a liquid coating composition.  
   
   
       36 . The electrodeposition process according to  claim 33 , further comprising curing the liquid coating composition prior to said immersing step.  
   
   
       37 . The electrodeposition process according to  claim 33 , wherein said step of applying an electrical current takes place prior to said immersing step.  
   
   
       38 . The electrodeposition process according to  claim 37 , wherein the electrical current is applied to the coated substrate or to the bath.  
   
   
       39 . The electrodeposition process according to  claim 33 , wherein the second period of time is a period of 0 seconds to about 12 hours.  
   
   
       40 . The electrodeposition process according to  claim 33 , wherein said etching step comprises: 
 applying an electrical current of reverse polarity for a period of time, and applying an electrical current of beginning polarity for a period time.    
   
   
       41 . The electrodeposition process according to  claim 40 , further comprising repeating said step of applying an electrical current of beginning polarity.  
   
   
       42 . The electrodeposition process according to  claim 40 , wherein the period of time of applying an electrical current of reverse polarity is a period of about 0.1 second to about 1 minute.  
   
   
       43 . The electrodeposition process according to  claim 40 , wherein the period of time of applying an electrical current of beginning polarity is a period of about 0.1 second to about 1 minute.  
   
   
       44 . The electrodeposition process according to  claim 41 , wherein said repeating step is carried out at least once.  
   
   
       45 . The electrodeposition process according to  claim 41 , wherein said repeating step is carried out two times.  
   
   
       46 . The electrodeposition process according to  claim 33 , wherein said etching step is repeated at least once.  
   
   
       47 . The electrodeposition process according to  claim 33 , wherein the liquid coating composition comprises a material selected from the group consisting of polymeric materials, polar liquids, non-polar liquids, surface tension-modifying compounds, antioxidants, organic liquids, petroleum-based substances, waxes, buffering materials, particulate suspensions, colloidal materials, resins, and mixtures thereof.  
   
   
       48 . The electrodeposition process according to  claim 33 , wherein the liquid coating composition comprises a lower alkyl carboxylic acid moiety.  
   
   
       49 . The electrodeposition process according to  claim 48 , wherein the lower alkyl carboxylic acid moiety is derived from sodium propionate.  
   
   
       50 . The electrodeposition process according to  claim 48 , wherein the liquid coating composition further comprises at least one moiety selected from the group consisting of a 2,4-trans, trans-hexadienoic moiety, a benzoic moiety, a phosphate moiety, a citrate moiety, acids and salts thereof, and mixtures thereof.  
   
   
       51 . The electrodeposition process according to  claim 33 , wherein the liquid coating composition comprises an electrically conductive material.  
   
   
       52 . The electrodeposition process according to  claim 33 , wherein the liquid coating composition comprises a positive charge.  
   
   
       53 . The electrodeposition process according to  claim 33 , wherein the material for electrodeposition comprises a metal.  
   
   
       54 . The electrodeposition process according to  claim 53 , wherein the metal comprises a transition metal.  
   
   
       55 . The electrodeposition process according to  claim 33 , wherein the material for electrodeposition comprises a conductive polymer.  
   
   
       56 . The electrodeposition process according to  claim 33 , wherein the substrate comprises a metal.  
   
   
       57 . The electrodeposition process according to  claim 33 , wherein the substrate comprises a conductive polymer.  
   
   
       58 . An electrodeposition process comprising: 
 coating a substrate with a liquid coating composition;    immersing the coated substrate in a bath comprising a material for electrodeposition;    applying for a first period of time an electrical current of specified voltage to form an initial uniform electrodeposition coating on the substrate;    reducing the voltage of the electrical current; and    applying the reduced voltage electrical current for a second period of time to form a final electrodeposition coating of a desired thickness.    
   
   
       59 . The electrodeposition process according to  claim 58 , further comprising adjusting the electrical current during the second period of time.  
   
   
       60 . An electrodeposition process comprising: 
 coating a substrate with a liquid coating composition comprising a lower alkyl carboxylic acid moiety;    immersing the coated substrate in a bath comprising a material for electrodeposition;    applying for a first period of time an electrical current of specified voltage to form an initial uniform electrodeposition coating on the substrate;    reducing the voltage of the electrical current; and    applying the reduced voltage electrical current for a second period of time to form a final electrodeposition coating of a desired thickness.    
   
   
       61 . The electrodeposition process according to  claim 60 , further comprising adjusting the electrical current during the second period of time.  
   
   
       62 . An electrodeposition process comprising: 
 coating a substrate with a liquid coating composition;    applying to the coated substrate an electrical current having a specified voltage;    immersing the coated substrate with the electrical current applied thereto in a bath comprising a material for electrodeposition;    continuing application of the electrical current for a first period of time;    reducing the voltage of the electrical current; and    continuing the application of the electrical current for a second period of time to form a final electrodeposition coating of a desired thickness.    
   
   
       63 . The electrodeposition process according to  claim 58 , further comprising adjusting the electrical current during the second period of time.  
   
   
       64 . An electrodeposition process comprising: 
 a) coating a substrate with a liquid coating composition;    b) immersing the coated substrate in a bath comprising a material for electrodeposition;    c) applying for a first period of time an electrical current of specified voltage having a beginning polarity to form an initial electrodeposition coating on the substrate;    d) reducing the voltage of the electrical current;    e) applying the reduced voltage electrical current for a second period of time to form a final electrodeposition coating of a desired thickness;    f) applying an electrical current of reverse polarity for a period of time;    g) applying an electrical current of beginning polarity for a period of time;    h) repeating at least once said step of applying an electrical current of beginning polarity; and    i) optionally repeating steps f) through h).    
   
   
       65 . A process for improving lubricity of a substrate comprising: 
 coating the substrate with a liquid coating composition;    applying an electrodeposition layer to the coated substrate; and    etching the electrodeposition layer.    
   
   
       66 . The process for improving lubricity of a substrate according to  claim 65 , wherein said etching step comprises 
 applying an electrical current of positive polarity for a period of time, and    applying an electrical current of negative polarity for a period of time.    
   
   
       67 . The process for improving lubricity of a substrate according to  claim 66 , further comprising repeating said step of applying an electrical current of negative polarity.  
   
   
       68 . The process for improving lubricity of a substrate according to  claim 66 , wherein the period of time for applying an electrical current of positive polarity is a period of about 0.1 second to about  1  minute.  
   
   
       69 . The process for improving lubricity of a substrate according to  claim 66 , wherein the period of time for applying an electrical current of negative polarity is a period of about 0.1 second to about 1 minute.  
   
   
       70 . A process for improving adhesion on a substrate comprising: 
 coating the substrate with a liquid coating composition;    applying an electrodeposition layer to the substrate; and    etching the electrodeposition layer.    
   
   
       71 . The process for improving adhesion of a substrate according to  claim 70 , wherein said etching step comprises 
 applying an electrical current of positive polarity for a period of time, and    applying an electrical current of negative polarity for a period of time.    
   
   
       72 . The process for improving adhesion of a substrate according to  claim 71 , further comprising repeating said step of applying an electrical current of negative polarity.  
   
   
       73 . The process for improving adhesion of a substrate according to  claim 71 , wherein the period of time of applying an electrical current of positive polarity is a period of about 0.1 second to about 1 minute.  
   
   
       74 . The process for improving adhesion of a substrate according to  claim 71 , wherein the period of time for applying an electrical current of negative polarity is a period of about 0.1 second to about 1 minute.  
   
   
       75 . A process for improving corrosion resistance of a substrate comprising: 
 coating the substrate with a liquid anti-corrosive composition;    immersing the coated substrate in a bath comprising a material for electrodeposition; and    applying an electrical current of a specified voltage to form an electrodeposition coating on the substrate.