Liquid crystalline composition having a dark black color
A shaped part that is formed from a polymer composition that contains a liquid crystalline polymer and a black pigment is provided. By selectively controlling the type and relative concentration of these components, the polymer composition and shaped parts formed therefrom can have a dark black appearance, and yet still exhibit good thermal and mechanical properties at high temperatures.
1. A liquid crystalline polymer composition that comprises a thermotropic liquid crystalline polymer and a black pigment that includes a plurality of carbon black particles in an amount of from about 1.5 wt. % to about 6 wt. % of the polymer composition, wherein the carbon black particles have an average size ranging from about 10 to about 100 nanometers, wherein the composition defines a black surface when shaped into a plaque having a size of 60 millimeters×80 millimeters by 3 millimeters, and wherein the black surface is characterized according to the CIELAB test by a L* value of from 0 to 30, wherein L*=is a luminosity value ranging from 0 to 100, where 0=black and 100=white.
2. The polymer composition of claim 1 , wherein the liquid crystalline polymer composition contains polynuclear aromatic hydrocarbons in an amount of about 1 part per million or less.
3. The polymer composition of claim 1 , wherein liquid crystalline polymers constitute from about 25 wt. % to about 75 wt. % of the polymer composition.
4. The polymer composition of claim 1 , wherein the black surface is characterized according to the CIELAB test by a b* value of about 4 or less, wherein b* is the yellow/blue axis and ranges from −100 to 100, where positive values are yellowish and negative values are bluish.
5. The polymer composition of claim 1 , wherein the liquid crystalline polymer contains repeating units derived from an aromatic dicarboxylic acid, aromatic hydroxycarboxylic acid, aromatic diol, aromatic amide, aromatic amine, or a combination thereof.
6. The polymer composition of claim 5 , wherein the polymer further comprises one or more repeating units derived from an aromatic diol, aromatic amide, aromatic amine, or a combination thereof.
7. The polymer composition of claim 1 , wherein the liquid crystalline polymer is wholly aromatic.
8. The polymer composition of claim 1 , wherein the total amount of repeating units in the liquid crystalline polymer derived from naphthenic hydroxycarboxylic acids and/or naphthenic dicarboxylic acids is more than 15 mol. %.
9. The polymer composition of claim 8 , wherein the liquid crystalline polymer further contains monomer units derived from 4-hydroxybenzoic acid, terephthalic acid, isophthalic acid, 4,4′-biphenol, hydroquinone, acetaminophen, or a combination thereof.
10. The polymer composition of claim 1 , wherein the black pigment further contains a carrier resin.
11. The polymer composition of claim 1 , wherein the polymer composition further comprises an inorganic particulate filler in an amount from about 5 wt. % to about 60 wt. % of the composition.
12. The polymer composition of claim 11 , wherein the inorganic particulate filler includes talc.
13. The polymer composition of claim 1 , wherein the polymer composition further comprises a fibrous filler in an amount from about 1 wt. % to about 40 wt. % of the composition.
14. The polymer composition of claim 13 , wherein the fibrous filler includes glass fibers.
15. The polymer composition of claim 1 , wherein the liquid crystalline polymer composition has a blister free temperature of about 270° C. or greater.
16. The polymer composition of claim 1 , wherein the liquid crystalline polymer composition exhibits a deflection temperature under load of from about 250° C. to about 350° C., as determined in accordance ISO Test No. 75-2 at a load of 1.8 Megapascals.
17. The polymer composition of claim 1 , wherein the liquid crystalline polymer composition is injection or compression molded.
18. The polymer composition of claim 1 , wherein the black pigment contains benzo[a]pyrene in an amount of about 10 parts per billion or less.
19. A shaped part comprising the polymer composition of claim 1 .