Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
2000-12-01
2001-12-18
Acquah, Samuel A. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S300000, C528S301000, C528S302000, C528S308000, C528S308600
Reexamination Certificate
active
06331606
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composition comprising a polyether diol and a sulfonated comononmer and to a process for producing the composition.
BACKGROUND OF THE INVENTION
Polyesters, especially polyalkylene terephthalates, have excellent physical and chemical properties and have been widely used for resins, films and fibers. In particular, polyester fibers have relatively high melting points, and can attain high orientation and crystallinity. Accordingly, polyesters have excellent fiber properties such as chemical, heat, and light stability, and high strength.
However, polyesters such as poly(propylene terephthalate) have relatively low toughness or impact strength when compared with other polymers such as poly(oxymethylene) (e.g., DELRIN available from E.I. du Pont de Nemours & Co., Wilmington Del.; hereinafter all terms written in upper cases are wither trade names or trademarks), nylon 66 (e.g., ZYTEL from the same source), and poly(butyleneterephalate-co-polytetramethylene glycol terephthalate) (e.g., HYTREL from the same source). Toughness is conventionally measured on an Instron machine (a tensile method, with units of in-lbf/in
3
or J/m
3
). Impact strength is conventionally measured by the “Izod” test wherein a heavy pendulum swings against a standard notched bar of the polymer. The energy required to just break the bar is recorded in ft-lbf/in or in-lbf/in (J/m, see Test Methods below). Poly(propylene terephthalate) impact strength measured by the Izod test is about 0.5 ft-lbf/in (27 J/m). By comparison, other polymers such as poly(oxymethylene), nylon 66, and poly(butylenelpoly tetramethylene ether terephthalate) have impact strengths of about 1.3, 2, and 3.7 ft-lbf/in (69, 107, and 198 J/m) respectively.
In other applications of poly(propylene terephthalate), the polymer is found to be difficult to dye. The high levels of orientation and crystallinity that impart desirable properties to the polyester contribute to the difficulty in dyeing, but a major factor is that polyesters, unlike protein fibers, do not have ionic sites within the polymer chain that are reactive to basic or acid dye compounds. A number of comonomers can be copolymerized with the polyester or polyamide as a means of conferring basic dyeability. Notable examples are aromatic sulfonates, their sodium salts, and specifically the sodium salts of 5-sulfoisophthalic acid or of dimethyl 5-sulfoisophthalate. While the use of comonomers such as 5-sulfoisophthalate salts provide an effective site for cationic dyes, the comonomers do not improve impact strength.
Elsewhere, the introduction of “soft segments” into polymer chains has been found to improve impact strength. Examples of soft segments are sections of the polymer chain comprised of poly(oxyalkylene) units. However, the extent to which impact strength may be increased by the introduction of such soft segments is limited by concurrent reduction in the tensile strength.
WO099/09238 discloses a polyester fiber prepared from a polyester prepared by copolymerizing polytrimethylene terephthalate with a third component. The third component is an ester-forming sulfonate compound used in a comononmer ratio of 0.5 to 5% by mole.
U.S. Pat. No. 5,097,004 discloses polyesters based upon polyethylene terephthalate copolyrnerized with a polyethylene glycol and a 5-sulfoisophthalic acid and, if desired, a polyethylene ether such as diethylene glycol.
There remains a need to develop a composition and a process for improving further the impact strength of the polyester composition.
SUMMARY OF THE INVENTION
A composition that can be used to produce, for example, fiber, film, or plastic is provided. The composition comprises repeat units derived from 1,3-propanediol, an organic acid, a polyether diol, and a sulfonated comonomer in which the polyether diol is present in the composition in the range of from about 10 to about 80 weight %.
Also provided is a process for producing the composition disclosed above. The process comprises contacting 1,3-propanediol with the organic acid, the polyether diol, and the sulfonated comonomer.
DETAILED DESCRIPTION OF THE INVENTION
The term “organic acid”, as discussed above can be a dicarboxylic acid, its ester, its salt, or combinations of two or more thereof. It can have the formula of R′O
2
CACO
2
R′ in which each R′ is independently selected from the group consisting of hydrogen, a C
1
to C
4
alkyl, a C
1
to C
4
hydroxyalkyl group, and combinations of two or more thereof. A is an alkylene group, an arylene group, or combinations thereof. An alkylene group can also contain unsaturation. Each A has about 2 to about 30, preferably about 3 to about 25, more preferably about 4 to about 20, and most preferably 4 to 15 carbon atoms per group. Examples of suitable dicarboxylic acids include, but are not limited to, terephthalic acid, isophthalic acid, naphthalic acid, succinic acid, adipic acid, phthalic acid, glutaric acid, oxalic acid, maleic acid, propanedioic acid, propenedioic acid, biphenylene dicarboxylic acid, and combinations of two or more thereof. The presently preferred dicarboxylic acid is terephthalic acid or ester thereof because the polyesters produced therefrom have a wide range of industrial applications.
Examples of suitable esters include, but are not limited to, dimethyl adipate, dimethyl phthalate, dimethyl terephthalate, dimethyl glutarate, and combinations of two or more thereof. The salt can be an alkali metal salt, an ammonium salt, or combinations of two or more thereof. The term “1,3-propanediol” can include a dihalopropane when the term “organic acid” is a salt. The preferred dihalopropane is 1,3-dichloroproane. Similarly, when a salt of organic acid is used, the term “polyether diol” refers to “polyether dihalide”, such as polyether dichloride.
Generally, in the composition, the molar ratio of repeat units derived from the total organic acid to the repeat units derived from total diol is about 1:1. Total diol includes the monomer 1,3-propanediol and the polyether diol. When a salt of the organic acid is used in combination with a 1,3-dihalopropane, the molar ratio of repeat units derived from the total organic acid to the sum of the repeat units derived from the polyether diol and the propyl residue is about 1:1. The polyether diol can be an oligomers of a C
3
to C
12
alkane diol, having the structure Of H—[—O—(C
a
H
2a
)—]
b
—OH in which a is 3-12 and preferably 3-4, and b is 2-25 such that the molecular weight [18+b(4
a
+16)] is within the range 200-1500.
The weight proportion of the polyether diol incorporated into the polyester composition can be defined in terms of its weight percent and can be between 10 and 80%, preferably between 10 and 40% by weight.
Examples of preferred low molecular weight polyether diols include, but are not limited to, the low molecular weight poly(tetramethylene glycols) available from E.I. du Pont de Nemours & Co., Wilmington, Del. under the tradename TERATHANE, such as poly(tetramethylene glycol) with molecular weight in the range 200-1500 (when a=4=~3-22 in the above formula) such as TERATHANE 650 and TERATHANE 1000). TERATHANE 650 having an average molecular weight of approximately 650 (when a=4, b =~8.5) and TERATHANE 1000 having an average molecular weight of approximately 1000 are particularly preferred. Poly(2,2-dimethyl-1,3-propanediol) or poly(neopentyl glycol) is a preferred example of a branched polyether diol.
The term “sulfonated comonomer” refers to, unless otherwise indicated, either aliphatic sulfonated dicarboxylic acid, ester thereof, or salt thereof; aromatic sulfonated dicarboxylic acid, ester thereof, or salt thereof; or combinations of two or more thereof. It can have the formula of (R′—O—C(O))
2
—A(R)
z
—S(O)
2
—O—M in which R′ and A are the same as those disclosed above. R is a C
1
to C
4
alkyl group or an aryl group. M is selected from hydrogen, an alkali metal ion, an alkaline earth metal ion, ammonium ion, quaternary ammo
Acquah Samuel A.
E. I. Du Pont de Nemours and Comapny
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