Compositions – Liquid crystal compositions
Patent
1999-06-16
2000-10-03
Wu, Shean C.
Compositions
Liquid crystal compositions
252601, 252609, 523521, C09K 1952, C09K 2114, C08K 334, C08K 6700
Patent
active
061268569
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to compositions comprising liquid crystalline polymers.
TECHNICAL BACKGROUND
Liquid crystalline polymers (LCPSs) have become important items of commerce, being useful as molding resins and in films for general purpose use, and more specifically in the automotive, electrical and electronic industries. In many of these uses fire or flame retardence, or resistance of varying degrees, is required of the polymers. Methods to make polymers in general, and LCPs in particular, more flame retardant are constantly being sought. Such methods are especially valuable when they do not significantly degrade the other important properties of the LCP and/or create other problems, such as general more toxic smoke during exposure to fire.
Japanese Patent application Publication 6-57117, published Mar. 1, 1994 (Sumitomo Chemical Company) describes the use of zeolites as fillers in LCPs for reducing the amount of volatiles when the LCPs are heated. No mention is made of flame or fire retardance.
BRIEF REFERENCE TO THE DRAWING
FIG. 1 shows the pellet Burn Times of a set of LCP compositions containing various zeolites vs. the UL-94 burn times (after aging 7 days at 70.degree. C.) for the same compositions.
This Figure illustrates that relative Pellet Burn Times are a good indicator if relative UL-94 burn times, and vica versa, for any given set of zeolite-containing LCP compositions.
SUMMARY OF THE INVENTION
This invention is a composition comprising a thermotropic liquid crystalline polymer which is an aromatic polyester, poly(ester-amide), poly(ester-imide), poly(ester-amide-imide), or mixtures thereof, and about 1.0-10 weight percent of an Inorganic Additive selected from zeolites and titanosilicates. The weight percent of the additive is based on weight of the thermotropic liquid crystalline polymer. The composition is characterized by the fact that at a polymer bar thickness of 0.79 mm, burn time is reduced by at least 15% when tested according to Underwriter's Laboratories test UL-94, the tested sample having been aged before testing for 7 days at 70.degree. C. The preferred Inorganic additive is zeolite and the preferred thermotropic liquid crystalline polymer is an aromatic polyester.
Preferred zeolites are 4A, 13X or NaP. Preferred zeolites are aluminosilicates having a Si/Al molar ration of 250 or less, more preferred 30 or less, even more preferred 10 or less, and most preferred 5 or less.
the compositions have a rating of V-0 in test UL-94. The composition's burn time is reduced by at least 30% or more. The flexural strength of the composition is at least 95% of the said thermotropic liquid crystalline polymer.
The weight percent zeolite based on the weight of said thermoplastic liquid crystalline polymer is preferably about 2.0-8.0 weight percent, more preferably about 2.0-5 weight percent.
DETAILS OF THE INVENTION
By an LCP is meant a polymer that is anisotropic when tested in the Thermo-Optical Test ("TOT") described in U.S. Pat. No. 4,118,372. By "thermotropic" is meant that the polymer may be melted and then resolidified, i.e. is thermoplastic. By "aromatic" is meant that, except for the carbon atoms contained in functional groups such as ester amide or imide, all of the carbon atoms in the main chain of the polymer are present in aromatic rings such as phenylene, naphthylylene, biphenylene, etc. Carbon atoms in other types of groupings such as alkyl may be present as substituents on the aromatic rings, as in a repeat unit derived from methylhydroquinone or 2-t-butyl-4-hydrozybenzoic acid, and/or also present at other places in the polymer such as in N-alkyl amides. Other substituent groups such as halogen, ether, and aryl may also be present in the LCP.
the LCPs useful in this invention include polyester, poly(ester-amides), poly(ester-imides) and poly(ester-amide-imides) and mixtures thereof. These terms have their usual meaning, and simply indicate that the repeat units in the polymer are joined by ester and optionally amide and/or imide linkages. LCP
REFERENCES:
patent: 5614568 (1997-03-01), Mawatari et al.
Corbin David Richard
Cottis Steven Gust
Plotzker Irene Greenwald
E.I. DuPont de Nemours and Company
Wu Shean C.
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