Functionalized quinacridone pigments
Quinacridone pigments that are surface-functionalized with glycidyl methacrylate, maleic anhydride, or 4-methacryloxyethyl trimellitic anhydride to create a functionalized pigment. The functional groups are then activated to bond hydrophobic polymers, thereby coating the pigment with the hydrophobic polymers. The quinacridone pigments can be used for a variety of applications. They are well-suited for use in electro-optic materials, such as electrophoretic media for use in electrophoretic displays.
1. A pigment comprising Formula I:
wherein R 1 is a hydrogen, a C 1 -C 3 alkyl group, a halogen, a hydroxyl, or —CH 2 CHR 4 CH 2 OCOR 3 ;
R 2 is a hydrogen, C 1 -C 3 alkyl group, or a halogen;
R 3 is —C(CH 3 )CH 2 , or a hydrophobic polymer having a molecular weight between 5 kD and 100 kD; and
R 4 is —OH or —O[CH 2 CH(CH 2 OCOC(CH 3 )CH 2 )O] x H, and x is an integer from 1 to 15.
2. The pigment of claim 1 , wherein the hydrophobic polymer is a polymer comprising lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-octadecyl acrylate, n-octadecyl methacrylate, or a combination thereof.
3. The pigment of claim 1 , comprising Formula II:
4. The pigment of claim 1 , comprising Formula III
wherein m and n are independently integers between 10 and 200.
5. The pigment of claim 1 , comprising Formula IV
wherein m and n are independently integers between 10 and 200.
6. The pigment of claim 1 , wherein R 2 is —H or R 2 is —CH 3 .
7. An electrophoretic medium comprising a pigment of claim 1 .
8. An electro-optic display comprising a pigment of claim 1 .
9. A front plane laminate comprising a pigment of claim 1 .
10. A method for making a functionalized pigment, comprising:
providing a pigment comprising Formula V:
wherein R is a hydrogen, C 1 -C 3 alkyl group, or a halogen; and
reacting the pigment with glycidyl methacrylate, maleic anhydride, or 4-methacryloxyethyl trimellitic anhydride monomers to create a functionalized pigment.
11. The method of claim 10 , wherein the pigment is dispersed in toluene and reacted with methacrylate, maleic anhydride, or 4-methacryloxyethyl trimellitic anhydride at a temperature greater than 40° C.
12. The method of claim 10 , further comprising reacting the functionalized pigment with a hydrophobic polymer.
13. The method of claim 12 , wherein the functionalized pigment and the hydrophobic polymer are ball milled together prior to reacting.
14. The method of claim 12 , wherein the hydrophobic polymer is a polymer comprising lauryl acrylate, lauryl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, hexyl acrylate, hexyl methacrylate, n-octyl acrylate, n-octyl methacrylate, n-octadecyl acrylate, n-octadecyl methacrylate, or a combination thereof.
15. The method of claim 10 , wherein the pigment is a magenta pigment.