Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-07-31
2001-07-17
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S272000
Reexamination Certificate
active
06262220
ABSTRACT:
BRIEF DESCRIPTION OF THE INVENTION
New polyester compositions containing terephthalate (T), isophthalate (I) and 2,6-naphthalate (N) moieties that are semi-crystalline and have a density of about 1.362 g/cm
3
or greater are disclosed. The compositions are useful for making films, fibers and containers for packaging.
This invention is also novel semi-crystalline polyesters containing specific mole ratios of terephthalate, isophthalate and naphthalate moieties (i.e., T/I/N and T/I) useful for producing fabricated articles that exhibit unexpectedly high density levels which are typically associated with a high level of crystallinity. The high density level is achieved by strain induced crystallization, thermal crystallization, or preferably a combination of strain induced crystallization and thermal crystallization. The polyesters of this invention have enhanced performance properties, in particular they exhibit excellent gas barrier properties.
This invention is a polyester composition comprising the following repeating unit:
where in any unit x is an integer selected from 2 through 6, inclusive, and where in at least a portion of the units R is 1,3-phenyl, in at least a portion of the units R is 1,4-phenyl and in at least a portion of the units R is 2,6-naphthyl, and where the density of the polyester is at least about 1.362 g/cm
3
. Preferably in about 80 to about 96 mole percent of the units R is 1,4-phenyl, and in about 20 to about 4 mole percent of the units R is selected from 1,3-phenyl and 2,6-naphthyl where the mole ratio of 1,3-phenyl to 2,6-naphthyl is about 1:5 to about 5:1. This invention is also the polyester composition where in at least a portion of the units R is 1,4-phenyl and where in at least about 5 mole percent, preferably at least about 8 mole percent, more preferably about 5 to about 25 mole percent, and most preferably about 10 to about 15 mole percent of the units in the polyester R is 1,3-phenyl, and preferably where in at least about 75 mole percent, more preferably about 75 to about 95 mole percent, and most preferably about 85 to about 95 mole percent of the units R is 1,4-phenyl, and where the density of the polyester is preferably at least about 1.362 g/cm
3
. By 1,4-phenyl we mean a phenyl ring where the carboxylate groups of the polyester polymer unit are attached to the 1 and 4 positions of the phenyl ring, by 1,3-phenyl we mean a phenyl ring where the carboxylate groups of the polyester polymer unit are attached to the 1 and 3 positions of the phenyl ring, and by 2,6-naphthyl we mean a naphthalene ring where the carboxylate groups of the polyester polymer unit are attached to the 2 and 6 positions of the naphthalene ring. Preferably, x is 2. While the preferred polyesters of this invention are those where the only polymer ester units present are those where R is 1,4-phenyl, 1,3-phenyl and 2,6-naphthyl, or where R is 1,4-phenyl and 1,3-phenyl; the polyesters of this invention can also contain ester units where R is some other moiety, such as an aliphatic or other type of aromatic moiety.
This invention is a polyester composition comprising terephthalate and isophthalate moieties, or comprising terephthalate, isophthalate and 2,6-naphthalate moieties, which compositions have been subjected to strain induced crystallization, or a combination of strain induced and thermal crystallization. By terephthalate moiety we mean that ester unit or part of the polyester based on or derived from terephthalic acid or its equivalent; by isophthalate moiety we mean that ester unit or part of the polyester based on or derived from isophthalic acid or its equivalent; and by 2,6-naphthalate moiety we mean that unit or part of a polyester molecule based on or derived from 2,6-naphthalenedicarboxylic acid or its equivalent. The equivalent of terephthalic acid, isophthalic acid and 2,6-naphthalic acid can be, for example, the dimethyl ester or the diacid halide.
BACKGROUND
Poly(ethylene terephthalate) (PET) has been modified with low levels of isophthalic acid (i.e., up to about 3 mole percent) primarily to adjust (decrease) the rate of crystallization of PET, in order to obtain amorphous articles such as partially oriented yams, amorphous sheets for thermoforming or biaxially oriented film fabrication, and bottle/jar preforms for injection stretch-blow molded containers. For most applications, however, it is most desired that the final fabricated article exhibit a high level of crystallinity, typically measured by density value. Crystallinity imparts high stiffness, low creep, improved barrier properties and other desired performance properties.
There is a need to modify PET to produce fabricated articles that have a combination of high density and enhanced performance properties, such as stiffness and barrier to gases. We have discovered that PET modified with a combination of isophthalate and 2,6-naphthalate moieties provides such improved polyesters. We have also discovered that PET modified with isophthalate moieties at levels at or greater than about 5 mole percent provides such improved properties.
REFERENCES:
patent: 4340721 (1982-07-01), Bonnebat et al.
patent: 4403090 (1983-09-01), Smith
Bauer Charles W.
Paschke Edward E.
Robertson Frank C.
Tibbitt James M.
Boykin Terressa M.
BP Amoco Corporation
Hall Jennifer M.
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