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 shaped part comprising a liquid crystalline polymer composition, the liquid crystalline polymer composition 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 and contain polynuclear aromatic hydrocarbons in an amount of about 1 part per million or less, wherein the composition defines a black surface of the part that is characterized according to the CIELAB test by a L* value of from 0 to 28, wherein L*=is a luminosity value ranging from 0 to 100, where 0=black and 100=white.
2. The shaped part of claim 1 , wherein liquid crystalline polymers constitute from about 25 wt. % to about 75 wt. % of the polymer composition.
3. The shaped part of claim 1 , wherein the black surface is also 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.
4. The shaped part 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.
5. The shaped part of claim 4 , wherein the polymer further comprises one or more repeating units derived from an aromatic dial, aromatic amide, aromatic amine, or a combination thereof.
6. The shaped part of claim 1 , wherein the liquid crystalline polymer is wholly aromatic.
7. The shaped part 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. %.
8. The shaped part of claim 7 , 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.
9. The shaped part of claim 1 , wherein the black pigment further contains a carrier resin.
10. The shaped part of claim 1 , wherein the polymer composition comprises an inorganic particulate filler in an amount from about 5 wt % to about 60 wt. % of the composition.
11. The shaped part of claim 10 , wherein the inorganic particulate filler includes talc.
12. The shaped part of claim 1 , wherein the polymer composition comprises a fibrous filler in an amount from about 1 wt. % to about 40 wt. % of the composition.
13. The shaped part of claim 12 , wherein the fibrous filler includes glass fibers.
14. The shaped part of claim 1 , wherein the shaped part has a blister free temperature of about 270° C. or greater.
15. The shaped part of claim 1 , wherein the deflection temperature under load is from about 250° C. to about 350° C., as determined in accordance ISO Test No. 75-2 at a load of 1.8 Megapascals.
16. The shaped part of claim 1 , wherein the part is injection or compression molded.
17. A foodstuff article comprising the shaped part of claim 1 .
18. The foodstuff article of claim 17 , wherein the article is cookware or bakeware.
19. The shaped part of claim 1 , wherein the black pigment contains benzo[a]pyrene in an amount of about 10 parts per billion or less.