Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Mixing of two or more solid polymers; mixing of solid...
Reexamination Certificate
2003-06-10
2004-05-18
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Mixing of two or more solid polymers; mixing of solid...
C528S279000, C528S283000, C528S293000, C528S295000, C528S295300, C528S298000, C528S299000, C528S300000, C528S302000, C528S306000, C528S308000, C528S308600, C525S437000, C524S483000
Reexamination Certificate
active
06737481
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to copolymers of dibasic acids with dianhydrosugar alcohols and the incorporation of such copolymers in polyesters. The polyesters of the present invention provide important property improvements.
BACKGROUND OF THE INVENTION
Charbonneau et al. in U.S. Pat. No. 6,063,464 have shown that incorporation of dianhydrosugar alcohols, such as 1,4:3,6-dianhydrosorbitol, hereinafter referred to by its trivial name “isosorbide”, can significantly raise the glass transition temperature (T
g
) of terephthalate polyesters, such as poly(1,3-propanediol terephthalate). Poly(1,3-propanediol terephthalate), also known as poly(trimethylene terephthalate), is hereinafter abbreviated as 3GT. The relatively low glass transition temperature (Tg) of 3GT (~45-50° C.) can lead to slight tackiness of the polymer when stored at high temperatures. An instance of this is sometimes evidenced on spools of fiber stored in warehouses in the hot weather of tropical countries. An increase in Tg lowers tack. Additionally, the low Tg leads to instability in spun fibers when stored under hot conditions. Partially drawn fibers under such storage conditions tend to undergo crystallization, forming a denser phase and causing fiber shrinkage, changes in denier and other undesirable changes in physical properties on storage. However, esterification of isosorbide with terephthalic acid or transesterification with dialkyl terephthalates involves the reaction of secondary hydroxyls and is slow compared with reaction of primary glycols such as ethylene glycol or 1,3-propylene glycol. This tends to lead to inefficient incorporation of the isosorbide. Using conventional condensation polymerization, this lower reactivity can lead to final polyesters that have lower molecular weights since unreacted isosorbides are detrimental to subsequent polymerization.
There are limits to the extent the esterification or transesterification reactions of isosorbide with terephthalic acid or its esters can be driven by higher reaction temperatures, since any resulting degradation or significant color formation in the product polyester is undesirable. Additionally, polyesters formed from 1,3-propane diol can form acrolein if the polymerization temperatures are too high.
Adelman et al. U.S. Ser. No. 10/172112 have described process improvements for the preparation of poly(1,3-propylene-co-isosorbide)terephthalate, hereinafter abbreviated as 3GIT. However, the secondary hydroxyl groups of the isosorbide with the dibasic acid or its dialkyl ester have much lower reactivity than the corresponding reactivity of the primary hydroxyl groups of the 1,3-propane diol. This difference in reactivity has a number of effects, one of which is to lengthen the time needed for the solid phase polymerization step, a final procedure wherein the inherent viscosity of the polymer increased to about 1.1 dl/g for good spinning properties.
It is desirable to prepare 3GITs with a low level of color and a Tg higher than the 45-50° C. Tg of 3GT, and, most importantly, both a low level of color and a higher Tg. Such improved properties aid in the use of 3GIT in many markets, including beverage bottles, film or sheet, fibers, monofilaments, and optical articles (e.g., compact discs or digital versatile discs). In many of these markets, aesthetics are important, and having a very low color resin is highly desirable.
The present invention provides readily prepared esters of dianhydrosugar alcohols and acids that are incorporated into poly(alkylene ester) polymers. These ester oligomers provide a facile process for the efficient incorporation of anhydrosugar alcohols into polyesters and the resulting polyesters are suitable for the manufacture of fibers, films, and engineering plastics with advantageous properties.
SUMMARY OF THE INVENTION
The present invention comprises poly(alkylene-co-dianhydrosugar ester) dicarboxylate polymers.
The present invention further comprises a polymer comprising the reaction product of alkylene diol, dicarboxylic acid, and a moiety of formula 1
X-I
a
-(A-I)
n
-A
b
-X Formula 1
wherein:
A is the ester residue from an anhydrosugar alcohol or dianhydrosugar alcohol,
I is the ester residue from a diacid or its dialkyl esters,
X is H when linked to an A residue, OH when linked to an I residue derived from a dibasic acid, and OR when linked to an I residue derived from a dialkyl ester of the dibasic acid,
R is a C1-C4 straight or branched chain alkyl group,
a and b are independently 0 or 1, and
n is 1 to 10
The present invention further comprises an ester comprising formula 1
X-I
a
-(A-I)
n
-A
b
-X Formula 1
wherein:
A is the ester residue from an anhydrosugar alcohol or dianhydrosugar alcohol,
I is the ester residue from a diacid or its dialkyl esters,
X is H when linked to an A residue, OH when linked to an I residue derived from a dibasic acid, and OR when linked to an I residue derived from a dialkyl ester of the dibasic acid,
R is a C1-C4 straight or branched chain alkyl group,
a and b are independently 0 or 1, and
n is 1 to 10.
The present invention further comprises a process of incorporating a dianhydrosugar alcohol into a polyester comprising
A) contacting a dianhydrosugar alcohol with an acid to yield an ester, or contacting a dialkyl ester with a dianhydrosugar alcohol to yield an ester, and
B) polycondensing said ester with a polyalkylene ester oligomer.
DETAILED DESCRIPTION OF THE INVENTION
Trademarks are hereinafter shown in upper case.
The present invention comprises poly(alkylene-co-dianhydrosugar ester) dicarboxylate polymers having a Tg of at least about 50, preferably at least about 54. Preferred are poly(alkylene-co-dianhydrosugar ester) terephthalate polymers. The present invention also describes polymerization processes to incorporate dianhydrosugar diol-containing bridging moieties into polyester and co-polyester polymers, including for example poly(ethylene terephthalate), poly(trimethylene terephthalate), and poly(tetramethylene terephthalate), and poly(alkylene 1,4-cyclohexanedicarboxylate). The processes avoid the problems created by the slow reaction rate for direct esterification or transesterification of isosorbide with terephthalic acid or dimethylterephthlate. The process of the present invention, in comparison with the prior art, significantly improves the incorporation of dianhydrosugar alcohols into polyesters by preparing a preformed bridging moiety of Formula 1
X-I
a
-(A-I)
n
-A
b
-X Formula 1
wherein:
A is the ester residue from an anhydrosugar alcohol or dianhydrosugar alcohol,
I is the ester residue from a diacid or its dialkyl esters,
X is H when linked to an A residue, OH when linked to an I residue derived from a dibasic acid, and OR when linked to an I residue derived from a dialkyl ester of the dibasic acid,
R is a C1-C4 straight or branched chain alkyl group,
a and b are independently 0 or 1, and
n is 1 to 10.
The ester residue from the diacid is the diacid with the hydroxyl groups removed. The ester residue from the alcohol is the alcohol with the hydrogens of the hydroxyl groups removed.
Formula 1 comprises esters of anhydrohexitols, such as the dianhydride isosorbide (1,4:3,6-dianhydrosorbitol) with dibasic acids such as isophthalic and phthalic acids, prepared by the esterification of the acid with the diol or by transesterification of the dialkyl ester of the diacid with the diol. Such esters are referred to hereinafter as “bridging moieties”. The invention further comprises the composition of polyesters incorporating such bridging moieties into polyester polymers, and the process for incorporating such bridging moieties into said polyester polymers.
One example of the structure of the bridging moiety of Formula 1 prepared from isosorbide and isophthalic acid or dimethylisosphthalate, wherein a is 0, b is 0, and n is 1 to 10, has the structure of Formula II:
The actual bridging moiety is typically a mixture of the above esters with n having a value of 1 to about 10, with the ester having n=1 predominating.
Th
Kurian Joseph V.
Liang Yuanfeng
Acquah Samuel A.
E. I. du Pont de Nemours and Company
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