Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Reexamination Certificate
2001-10-31
2003-07-29
Acquah, Samuel A. (Department: 1711)
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
C528S176000, C528S190000, C528S193000, C528S194000, C528S298000, C528S300000, C528S301000, C528S302000, C528S307000, C528S308000, C528S308600, C428S359000, C428S373000, C428S375000
Reexamination Certificate
active
06599625
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polyether ester elastomers, and manufacture and use thereof.
TECHNICAL BACKGROUND
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 similar properties as chemical crosslinks in traditional thermosetting elastomers, while the soft segments provide rubber-like properties.
The weight and mole ratios of hard to soft segments, as well as the type of the segments determines to a great extent the properties of the resulting TPE. For example, longer soft segments usually lead to TPEs having lower initial tensile modulus, while a high percent of hard segments leads to polymers with higher initial tensile modulus. Other properties may be affected as well. Thus, manipulation on the molecular level affects changes in the properties of TPEs, and improved TPEs are constantly being sought.
Frequently the soft segments of TPEs are formed from poly(alkylene oxide) segments. Heretofore the principle polyether polyols have been based on polymers derived from cyclic ethers such as ethylene oxide, 1,2-propylene oxide and tetrahydrofuran. These cyclic ethers are readily available from commercial sources, and when subjected to ring opening polymerization, provide the polyether glycol, e. g., polyethylene ether glycol (PEG), poly(1,2-propylene) glycol (PPG), and polytetramethylene ether glycol (PO4G, also referred to as PTMEG), respectively.
U.S. Pat. No. 3,023,192 Shivers discloses segmented copolyetheresters and elastic polymer yarns made from them. The segmented copolyetheresters are prepared from (a) dicarboxylic acids or ester-forming derivatives, (b) polyethers of the formula HO(RO)
n
H, and (c) dihydroxy compounds selected from bis-phenols and lower aliphatic glycols. R is a divalent radical, and representative polyethers include polyethylene ether glycol, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, and so on, and n is an integer of a value to provide a polyether with a molecular weight of about 350-6,000.
U.S. Pat. No. 3,651,014 Witsiepe discloses copolyetheresters consisting of recurring long chain and short chain ester units. The long chain ester units are represented by the formula:
The short chain ester units are represented by the formula:
R and R′ are divalent radicals remaining after removal of carboxyl groups from a dicarboxylic acid having a molecular weight of less than 300. G is a divalent radical remaining after removal of terminal hydroxyl groups from a long chain polymeric ether glycol, having a molecular weight greater than 600 and a melting point below 55° C. D is a divalent radical remaining after removal of terminal hydroxyl groups from a low molecular weight diol. The copolyesters of this patent are prepared from dicarboxylic acids (or their equivalents), (b) linear long chain glycols and (c) low molecular weight diols; provided however, that there must be used either at least two dicarboxylic acids (or their equivalents) or at least two low molecular weight diols. A list of long chain glycols including “poly(1,2 and 1,3-propylene oxide) glycol” is present at column 4; however, the examples are directed to the use of PO4G as the long chain polymeric ether glycol.
U.S. Pat. No. 4,906,729 Greene et al. discloses segmented thermoplastic copolyetheresters having soft segments formed from a long chain polyalkyleneether glycol containing 80 to 97 mole percent of copolymerized tetrahydrofuran and 3 to 20 mole percent of a copolymerized cyclic alkylene oxide, preferably copolymerized 3-methyltetrahydrofuran, and fibers and films with an improved combination of tenacity, unload power, melting temperatures and set.
U.S. Pat. No. 4,937,314 Greene discloses thermoplastic copolyetherester elastomers comprising at least 70 weight % soft segments derived from poly(alkylene oxide) glycols and terephthalic acid. The hard segments constitute 10-30 weight % of the elastomer and are 95-100% poly(1,3-propylene terephthalate). The specification discloses that the poly(alkylene oxide) glycols have a molecular weight of about 1,500-about 5,000 and a carbon-to-oxygen ratio of 2-4.3. Representative poly(alkylene oxide) glycols include poly(ethylene oxide) glycol, poly(1,2-propylene oxide) glycol, poly(1,3-propylene oxide) glycol, poly(tetramethylene oxide) glycol (PO4G), etc. In the examples, the soft segments are based on PO4G and tetrahydrofuran/ethylene oxide copolyethers.
U.S. Pat. No. 5,128,185 Greene describes thermoplastic copolyetherester elastomers comprising at least 83 weight % soft segments derived from poly(alkylene oxide) glycols and terephthalic acid. The hard segments constitute 10-17 weight % of the elastomer and comprises poly(1,3-propylenebibenzoate). The specification discloses that the poly(alkylene oxide) glycols having a molecular weight of about 1,500-about 5,000 and a carbon-to-oxygen ratio of 2.5-4.3. Representative examples include poly(ethylene oxide) glycol, poly(1,2-propylene oxide) glycol, poly(1,3-propylene oxide) glycol, poly(tetramethylene oxide) glycol (PO4G), etc. In the examples, the soft segments are based on PO4G and tetrahydrofuran/3-methyl tetrahydrofuran.
JP 2000-256919 discloses a thermo-adhesive polyester conjugate fiber containing a polyether ester-type block copolymer having a hard segment consisting of a polytrimethylene terephthalate polyester and a soft segment component consisting of a poly(alkylene oxide) glycol having an average molecular weight of 400-5,000. Poly(1,2-propylene oxide) glycol, poly(ethylene oxide) glycol, and poly(tetramethylene oxide) glycol are among the disclosed soft segments, and the later is preferred. The conjugate fiber also contains a polytrimethylene terephthalate polyester section.
All of the aforementioned documents are incorporated herein by reference.
TPEs based on those exemplified in the prior art are primarily based on PO4G, copolymers of tetrahydrofuran and 3-alkyltetrahydrofuran, PEG, PPG and copolymers of these. While a range of polyether ester TPEs can be produced based on these polyethers, there remains the need for an overall improvement in physical properties, including tensile strength, elongation, and stretch-recovery properties, including tensile set and recovery power. The present invention provides distinct advantages toward achieving an overall improved balance of these properties. Particularly unexpected are a large increase in recovery power and a large decrease in stress decay.
SUMMARY OF THE INVENTION
The invention is directed to a polyether ester elastomer comprising about 90-about 60 weight % polytrimethylene ether ester soft segment and about 10-about 40 weight % trimethylene ester hard segment. They preferably contain at least about 70 weight %, more preferably at least about 74 weight %, polytrimethylene ether ester soft segment, and preferably contain up to about 85, more preferably up to about 82 weight %, polytrimethylene ether ester soft segment. They preferably contain at least about 15 weight %, more preferably at least about 18 weight %, and preferably contain up to about 30 weight %, more preferably up to about 26 weight %, trimethylene ester hard segment.
The mole ratio of hard segment to soft segment is preferably at least about 2.0, more preferably at least about 2.5, and is preferably up to about 4.5, more preferably up to about 4.0.
The polyether ester preferably has an inherent viscosity of at least about 1.4 dl/g, more preferably at least about 1.6 dl/g, and preferably up to
Goldfinger Marc B.
Sunkara Hari B.
Acquah Samuel A.
E. I. du Pont de Nemours and Company
Kuller Mark D.
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