Nucleating agent for polyesters

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...

Reexamination Certificate

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Reexamination Certificate

active

06245844

ABSTRACT:

FIELD OF THE INVENTION
This invention concerns polyester polymer compositions containing nucleating agents and a process for making such compositions. More specifically, it concerns the use of mono-sodium dicarboxylates, or precursors thereof, as nucleating agents.
TECHNICAL BACKGROUND OF THE INVENTION
Alkali metal or alkaline earth metal salts of polycarboxylic acids have been used in polyester polymers to increase the crystallinity or the rate of crystallization.
U.S. Pat. No. 3,761,450 describes molding compositions based on linear saturated polyesters comprising small amounts of lithium and/or sodium salts of polycarboxylic acids to bring about a high crystallinity in the heated mold after a short time. Polyesters and salts of polycarboxylic acids are disclosed generally. Poly(ethylene terephthalate) and disodium 1,10-dodecanedicarboxylate are exemplified.
U.S. Pat. No. 5,264,477 discloses an improved melt processable liquid crystalline polyester composition capable of forming an anisotropic melt phase and having an improved heat distortion temperature under a load by using 0.05 to 1.0 weight percent of a divalent metal salt of an aromatic dicarboxylic acid, wherein the metal is zinc, calcium, cadmium, barium or mixtures thereof.
U.S. Pat. No. 4,380,621 discloses fast crystallizing polyesters in which at least some of the acid end groups of the polyester have the formula —COO

M
+
where M
+
is an alkaline metal ion. Poly(ethylene terephthalate) and poly(butylene terephthalate) are specifically disclosed. Poly(ethylene terephthalate) is exemplified. Sodium containing species exemplified include sodium hydroxide, sodium benzoate and sodium o-chlorobenzoate.
SUMMARY OF THE INVENTION
This invention concerns a polyester composition comprising a mono-sodium salt of a dicarboxylic acid selected from the group consisting of monosodium terephthalate, mono sodium naphthalene dicarboxylate and mono sodium isophthalate as a nucleating agent. The invention also concerns a process for making a polyester composition useful as a nucleating agent.
In a preferred embodiment, the polyester is selected from the group consisting of poly(trimethylene naphthalate), poly(trimethylene isophthalate) and poly(trimethylene terephthalate). Most preferred is a composition comprising a poly(trimethylene terephthalate) and mono-sodium terephthalate as a nucleating agent. The monosodium terephthalate may be added to the system or may be generated in situ by the addition of an appropriate sodium containing species to a polymerization reaction mixture comprising terephthalic acid.
An especially desirable embodiment comprises poly(trimethylene terephthalate) and 0.005 to 2 wt % mono-sodium terephthalate.


REFERENCES:
patent: 3761450 (1973-09-01), Herwig et al.
patent: 4380621 (1983-04-01), Nield et al.
patent: 5264477 (1993-11-01), Wissbrun et al.
patent: 5356972 (1994-10-01), Sperling et al.
patent: 2014770 (1970-10-01), None
patent: WO 00 17265 (2000-03-01), None

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