Compositions – Liquid crystal compositions
Patent
1998-06-25
2000-02-08
Wu, Shean C.
Compositions
Liquid crystal compositions
25229962, 25229967, 524601, 524605, 528190, 528193, 528194, C09K 1952, C09K 1932, C08G 6300, C08L 6700
Patent
active
060224916
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention concerns a novel liquid crystalline polymer composition containing repeat units derived from hydroquinone, terephthalic acid, isophthalic acid, 2,6-naphthalene dicarboxylic acid and 4-hydroxybenzoic acid. This polymer is especially useful as a molding resin.
TECHNICAL BACKGROUND
Thermotropic liquid crystalline polymers (LCPs) are commercially important being particularly useful as molding resins where certain attributes, such as short molding cycles, low flammability, good moldability, stability at high temperatures, and/or chemical resistance are required. LCPs are used, inter alia, to make automotive parts, electrical and electronic parts such as connectors, and other small or difficult to mold parts.
One drawback to the use of such polymers has been the relatively high price of LCPs, which is partly due to the fairly expensive monomers used in their manufacture. Therefore it it has long been desired to not only find LCPs with improved properties, but also to find such LCPs that could be made from more reasonably priced and readily available monomers.
U.S. Pat. No. 4,169,933 describes the preparation of polymers containing repeat units derived from hydroquinone, terephthalic acid, 2,6-naphthalene dicarboxylic acid and 4-hydroxybenzoic acid. U.S. Pat. Nos. 5,079,289; 5,097,001; and 5,221,730 describe the preparation of polymers containing repeat units derived from hydroquinone, terephthalic acid, isophthalic acid and 4-hydroxybenzoic acid. Polymers of this invention are not described in any of these patents.
U.S. Pat. No. 5,492,946 relates to LCPs, and U.S. Pat. No. 4,851,497 to aromatic polyesters
SUMMARY OF THE INVENTION
This invention concerns a thermotropic LCP containing the following repeat units: ##STR1## their respective mole amounts per 100 moles of (I) present in said polymer being as follows: of (II)+(III)+(IV) present is 100 moles per 100 moles of (I).
DETAILS OF THE INVENTION
Repeat unit (I) is derived from hydroquinone. The term "derived", as used herein for the purpose of explaining the chemical character of each repeat unit, means that each such unit can be represented by a chemical formula obtained by removing the hydrogen atoms from the hydroxyl groups and removing the hydroxyl groups from the carboxyl groups of the named parent compounds. Repeat units (II). (III), and (IV) are derived, respectively, from terephthalic acid, isophthalic acid, and 2,6-naphthalene dicarboxylic acid. Repeat unit (V) is derived from 4-hydroxybenzoic acid.
In preferred polymers the respective mole amounts of repeat units (II), (III), (IV), and (V) per 100 moles of (I) are as follows, where it is sufficient that at least one of (II), (III), (IV), and (V) satisfy its recited range: about 15 to about 40 moles of (IV), and about 200 to about 300 moles of (V).
It also is preferred that these polymers have a melting point of about 365.degree. C. or less. more preferably about 350.degree. C. or less.
In addition to the above five principal repeating units (I) through (V), the polymer of this invention may contain small amounts of other units such as, for example, additional modifying dicarboxylic acid and aromatic diol units; for example, 2,7-naphthalene dicarboxylic acid, 1,4-cyclohexane dicarboxylic acid, and resorcinol. It is recognized that some commercially available materials may not have a 100% content of the nominal species or isomer, and that repeating units of unspecified monomers may thus also be present in the polymer. Normally, the total amount of repeating units other than those identified as (I) to (V), if present at all, will be very small, certainly less than about 10 mole % of the total moles,
These LCPs can be prepared by methods well known to the those skilled in the art for making aromatic polyesters. For instance, carboxylate esters, such as acetates, of hydroquinone and of 4-hydroxybenzoic acid may be reacted under heat, and later vacuum, with terephthalic, isophthalic, and 2,6-naphthalene dicarboxylic acids to form the desired polymer. Similarly,
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Samuels Michael Robert
Waggoner Marion Glen
E. I. Du Pont de Nemours and Company
Wu Shean C.
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