Cast molded parts formed from a liquid crystalline polymer

• US 9,045,685 B2
• Filed: 08/27/2012
• Issued: 06/02/2015
• Est. Priority Date: 08/29/2011
• Status: Expired due to Fees

• Current Assignee: Ticona LLC (Celanese Corporation)
• Original Assignee: Ticona LLC (Celanese Corporation)
• Inventors: Nair, Kamlesh P., Gray, Steven D., Grenci, Joseph J.
• Primary Examiner(s): WU, SHEAN CHIU
• Application Number:
  US13/594,923
• Publication Number:
  US 20130062558A1
• Time in Patent Office: 1,009 Days
• Field of Search: 252/299.5, 252/299.61, 252/299.62, 252/299.63, 252/299.67, 264/299, 524/100, 524/227
• US Class Current: 1/1
• CPC Class Codes: B29C 39/006 Monomers or prepolymers by reaction injection moulding B29C67/246
• CPC Class Codes: C08K 5/20 Carboxylic acid amides
• CPC Class Codes: C08K 5/34922 Melamine; Derivatives thereof
• CPC Class Codes: C08L 77/12 Polyester-amides
• CPC Class Codes: C09K 19/22 linked by a chain containing carbon and nitrogen atoms as chain links, e.g. Schiff bases
• CPC Class Codes: C09K 19/3086 in which at least two rings are linked by a chain containing nitrogen atoms
• CPC Class Codes: C09K 19/322 Compounds containing a naphthalene ring or a completely or partially hydrogenated naphthalene ring
• CPC Class Codes: C09K 19/3444 the heterocyclic ring being a six-membered aromatic ring containing one nitrogen atom, e.g. pyridine
• CPC Class Codes: C09K 19/48 containing Schiff bases
• CPC Class Codes: C09K 19/54 Additives having no specific mesophase characterised by their chemical composition
• CPC Class Codes: C09K 2019/0481 Phenylene substituted in meta position

Abstract

A molded part having a predetermined shape is provided. The molded part may be formed by casting a liquid crystalline polymer composition into a mold cavity at a relatively low shear rate. Due to the use of a relatively low shear rate, the polymer composition does not generally undergo extensive shear orientation, which can allow the resulting part to be further processed using standard finishing techniques. The ability to use relatively low shear rates during casting is achieved in the present invention through the use of an aromatic amide oligomer. More particularly, the present inventors have discovered that the aromatic amide oligomer can serve as a flow aid by altering intermolecular polymer chain interactions, thereby lowering the overall viscosity of the polymer matrix to “ultralow” levels without having a significant impact on the mechanical properties.

Claims

1. A molded part that is formed by casting a polymer composition into a mold cavity, wherein the polymer composition comprises a thermotropic liquid crystalline polymer and an aromatic amide oligomer, and wherein the polymer composition of the molded part has a melt viscosity of from about 0.1 to about 80 Pa-s, as determined at a shear rate of 1000 seconds⁻

1 and temperature of 350°

C. in accordance with ISO Test No. 11443.

2. The molded part of claim 1, wherein the liquid crystalline polymer is wholly aromatic.

3. The molded part of claim 1, wherein the liquid crystalline polymer contains monomer repeat units derived from one or more aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic dials, aromatic amines, aromatic diamines, or a combination of the foregoing.

4. The molded part of claim 3, wherein the liquid crystalline polymer contains monomer repeat units derived from 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, terephthalic acid, isophthalic acid, 4,4′

-biphenol, hydroquinone, acetaminophen, or a combination of the foregoing.

5. The molded part of claim 1, wherein the aromatic amide oligomer is employed in an amount of from about 0.1 to about 10 parts by weight relative to 100 parts by weight of the liquid crystalline polymer.

6. The molded part of claim 1, wherein the aromatic amide oligomer has a molecular weight of 3,000 grams per mole or less.

7. The molded part of claim 1, wherein the oligomer has from 2 to 8 amide bonds per molecule.

8. The molded part of claim 1, wherein the aromatic amide oligomer has the following general formula (I):

9. The molded part of claim 8, wherein ring B is phenyl, R₁ is phenyl or cyclohexyl, and R₂ is phenyl or cyclohexyl.

10. The molded part of claim 1, wherein the aromatic amide oligomer has the following general formula (IV):

11. The molded part of claim 1, wherein the aromatic amide oligomer has the following general formula (V):

12. The molded part of claim 1, wherein the aromatic amide oligomer is selected from the group consisting of the following compounds:

13. The molded part of claim 1, wherein the aromatic amide oligomer is N1,N4-diphenylterephthalamide, N1,N4-diphenylisoterephthalamide, 1,3-benzenedicarboxamide, N1,N3-dicyclohexyl, or 1,4-benzenedicarboxamide, N1,N3-dicyclohexyl.

14. The molded part of claim 1, wherein the composition has a melt viscosity of from about 1 to about 40 Pa-s, as determined at a shear rate of 1000 seconds⁻

1 and temperature of 350°

C. in accordance with ISO Test No. 11443.

15. The molded part of claim 1, wherein the part is a lineal part.

16. The molded part of claim 15, wherein the lineal part is a rod, tube, plate, bar, or sheet.

17. The molded part of claim 1, wherein the part has a cross-sectional thickness of from about 0.1 to about 50 millimeters.

18. The molded part of claim 1, wherein the part has a lengthwise dimension and a transverse dimension, wherein the part is substantially isotropic in the transverse and lengthwise dimensions.

34. The molded part of claim 1, wherein the polymer has a melting point.

35. The molded part of claim 34, wherein the melting point is from about 300°

C. to about 400°

C.

19. A method for forming a molded part, the method comprising:

casting a polymer composition into a mold cavity, wherein the polymer composition comprises a thermotropic liquid crystalline polymer and an aromatic amide oligomer; and

allowing the cast polymer composition to cool within the mold cavity to form the molded part, wherein the cast polymer composition has a melt viscosity of from about 0.1 to about 80 Pa-s, as determined at a shear rate of 1000 seconds<sup>−

1</sup> and temperature of 350°

C. in accordance with ISO Test No. 11443.

20. The method of claim 19, wherein the polymer composition is cast at a shear rate of less than about 200 s⁻

1.

21. The method of claim 19, wherein the polymer composition is cast at a shear rate of from about 2 to about 50 s⁻

1.

22. The method of claim 19, wherein the polymer composition is gravity cast into the mold cavity.

23. The method of claim 22, wherein the polymer composition is poured into the mold cavity from a container.

24. The method of claim 19, wherein the molding temperature ranges from about 290°

C. to about 450°

C.

25. The method of claim 19, wherein the liquid crystalline polymer is wholly aromatic.

26. The method of claim 19, wherein the liquid crystalline polymer contains monomer repeat units derived from one or more aromatic hydroxycarboxylic acids, aromatic dicarboxylic acids, aromatic diols, aromatic amines, aromatic diamines, or a combination of the foregoing.

27. The method of claim 19, wherein the liquid crystalline polymer contains monomer repeat units derived from 4-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, terephthalic acid, isophthalic acid, 4,4′

-biphenol, hydroquinone, acetaminophen, or a combination of the foregoing.

28. The method of claim 19, wherein the liquid crystalline polymer is formed in the presence of the aromatic amide oligomer.

29. The method of claim 19, wherein the liquid crystalline polymer is melt blended with the aromatic amide oligomer after the polymer is formed.

30. The method of claim 19, wherein the aromatic amide oligomer has the following general formula (I):

31. The method of claim 30, wherein ring B is phenyl, R₁ is phenyl or cyclohexyl, and R₂ is phenyl or cyclohexyl.

32. The method of claim 19, wherein the aromatic amide oligomer is selected from the group consisting of the following compounds:

33. The method of claim 19, wherein the aromatic amide oligomer is N1,N4-diphenylterephthalamide, N1,N4-diphenylisoterephthalamide, 1,3-benzenedicarboxamide, N1,N3-dicyclohexyl, or 1,4-benzenedicarboxamide, N1,N3 dicyclohexyl.