Polyether ester elastomer composition

Abstract

Disclosed are polyether ester elastomer compositions having polytrimethylene ether ester soft segments and polyethylene ester hard segments and containing a nucleating agent. Shaped articles can be made from these compositions, particularly molded articles, films and fibers.

Description

FIELD OF THE INVENTION[0001]This invention relates to thermoplastic polyether ester elastomers comprising polytrimethylene ether ester soft segment and polyethylene terephthalate ester hard segment containing nucleating agents, and manufacture and use thereof.BACKGROUND OF THE INVENTION[0002]Thermoplastic elastomers (TPEs) are a class of polymers which combine the properties of two other classes of polymers, namely thermoplastics, which may be reformed upon heating, and elastomers which are rubber-like polymers. One form of TPE is a block copolymer, usually containing some blocks whose polymer properties usually resemble those of thermoplastics, and some blocks whose properties usually resemble those of elastomers. Those blocks whose properties resemble thermoplastics are often referred to as “hard” segments, while those blocks whose properties resemble elastomers are often referred to as “soft” segments. It is believed that the hard segments provide properties similar to chemical c...

AI Technical Summary

Benefits of technology

[0031]Polyether esters containing the nucleating agents in accordance with the present invention exhibit short crystallization half times (t1 / 2) and early onsets of crystallization as measured by differential scanning calorimeter (DSC) in the heating and cooling cycle. Crystallization half time is the time needed for the degree of crystallinity to reach half of its ultimate value. The higher the onset crystallization temperature (Trc), the faster the crystallization rate. The presence of the nucleating agent used in accordance with the present invention lowers the crystallization half time of the polymer and speeds up the onset of the crystallization time (as well as the early appearance of the crystallization peak temperature) during the cooling phase of the polymer, all as measured by DSC analysis, to the extent necessary to effectively utilize the polymer in a variety of end-use applications.

[0032]These are desirable effects because such polymers can quickly become rigid, leading to faster demold times and shorter cycle times in processing them into shaped articles by such methods as thermoforming, injection molding, and blow molding. The ability to melt spin the polyether ester into fiber is also greatly enhanced by the effects of the nucleating agents.

[0033]A further result achieved by the practice of this invention is the improvement of physical properties of polyester polymers by increasing the crystallization rate and increasing the crystallinity.

[0034]When the compositions of this invention are compared to the same polyether ester polymers containing no nucleating agent, the polymers containing nucleating agent exhibit lower crystallization half times and earlier onsets of the crystallization time (early arrival of the crystallization peak temperature) during the cooling phase. It has also been found that the polyether ester comprising polytrimethylene ether ester soft segment and polyethylene ester hard segment exhibits improvement in brittleness, heat resistance and impact resistance.

Problems solved by technology

Their utility, however, has been limited, particularly in engineering resin applications, because of their relatively low rates of crystallization.

In fact, the unmodified polyether ester comprising polytrimethylene ether terephthalate soft segment and polyethylene terephthalate hard segment is unsuitable for most injection molding applications.

Low crystallization rates cause the polymer to be difficult to pelletize or flake, difficult to spin into fibers, and difficult to process into shaped articles by such methods as thermoforming, injection molding and blow molding, because ejection from the mold of an insufficiently crystallized molding would mean that the article could continue to crystallize when in service with appropriate volume changes.

It is, however, also generally known that a specific additive that works very efficiently for a particular polyester may not work well for others.

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