Cathodic electrocoating compositions
View Patent ↗Disclosed herein are functionalized polymers comprising ethylene and substituted ethylene segments, which have been modified by epoxidation to enhance their crosslinking ability. These functionalized polymers are useful as film forming resins in cathodic electrocoating compositions. Also disclosed herein are aqueous dispersion compositions comprising the functionalized polymers and a process for coating various electrically conductive substrates.
1. A polymer comprising:
a) at least one ethylene segment of structure 1
b) at least one substituted ethylene segment of structure 2
and
c) at least one substituted ethylene segment of structure 3
wherein:
x and y are independently integers from 10 to 30,000, and z is an integer from 1 to 10;
R is independently at least one member selected from the group consisting of: —(CH 2 ) m N(CH 3 ) 2 , —(CH 2 ) n —(CH═CH)—(CH 2 ) r CH 3 , —(CH 2 ) v CH 3 , —(CH 2 ) p OH, —(CH 2 ) s N(CH 2 CH 2 OH) 2 , and —(CH 2 ) t OPO 3 H 2 ;
R′ in structure 2 and R′ in structure 3 are independently H, —C q H 2q+1 , or —C q H 2q−k ;
R″ is H or CH 3 ;
R′″ is H, methyl, or phenyl;
q, r, s, t, m, n, v, and p are each independently selected from the integers from 1 to 20; and k is the number of saturated hydrocarbon rings in —C q H 2q−k .
2. The polymer of claim 1 , wherein R′ in structure 2 and R′ in structure 3 are H, and R is —(CH 2 ) n —(CH═CH)—(CH 2 ) r CH 3 .
3. The polymer of claim 2 , wherein n=8 and r=7.
4. The polymer of claim 1 , wherein R′ in structure 2 and R′ in structure 3 are H, and R is —(CH 2 ) n —(CH═CH)—(CH 2 ) r CH 3 or —(CH 2 ) p OH.
5. The polymer of claim 4 , wherein n=8, r=7, and p=2.
6. The polymer of claim 1 , wherein R′ in structure 2 and R′ in structure 3 are H, R is —(CH 2 ) n —(CH═CH)—(CH 2 ) r CH 3 or —(CH 2 ) p OH, and R′″ is H.
7. The polymer of claim 6 , wherein n=8, r=7, and p=2.
8. An aqueous dispersion composition comprising:
a) a polymer of claim 1 ; and
b) water;
wherein said aqueous dispersion composition has a pH of 5.0 to 7.0.
9. The aqueous dispersion composition of claim 8 further comprising at least one crosslinking agent.
10. The aqueous dispersion composition of claim 9 , wherein the at least one crosslinking agent is a blocked isocyanate.
11. The aqueous dispersion composition of claim 9 , wherein the at least one crosslinking agent is an alkoxysilane.
12. The aqueous dispersion composition of claim 8 further comprising at least one additive selected from the group consisting of: surfactants, pigments, light stabilizers, anti-crater agents, flow aids, dispersion stabilizers, adhesion promoters, corrosion inhibitors, and fillers.
13. The aqueous dispersion composition of claim 8 having a pH of 6.0 to 7.0.
14. The aqueous dispersion composition of claim 8 having a pH of 6.5 to 7.0.
15. A process comprising the steps of:
a) providing an electrochemical cell comprising:
i) an aqueous dispersion composition of claim 8 ;
ii) substrate to be coated, wherein the substrate is in contact with the aqueous dispersion composition and the substrate serves as a cathode of the electrochemical cell;
iii) an anode in contact with the aqueous dispersion composition; and
iv) a power supply in electrical contact with the anode and cathode; and
b) applying a voltage between the cathode and the anode to electrodeposit a polymer coating onto at least a portion of the substrate that is in contact with the aqueous dispersion.
16. The process of claim 15 further comprising the step of: heating the polymer coating.
17. The process of claim 15 wherein the aqueous dispersion further comprises a crosslinking agent.
18. The process of claim 15 wherein the aqueous dispersion further comprises at least one additive selected from the group consisting of: surfactants, pigments, light stabilizers, anti-crater agents, flow aids, dispersion stabilizers, adhesion promoters, corrosion inhibitors, and fillers.
19. A coated article produced by the process of claim 15 .