Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Statutory Invention Registration
1999-04-22
2001-08-07
Tudor, Harold J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
C524S366000, C524S368000
Statutory Invention Registration
active
H0001987
ABSTRACT:
FIELD OF THE INVENTION
This invention concerns non-volatile blends of one or more poly(alkylene ether)s or end-capped poly(alkylene ether)s with polyesters that provide faster crystallization rates at lower mold temperatures than polyesters alone.
BACKGROUND OF THE INVENTION
Crystallization rate as a function of temperature is often critical when injection molding semicrystalline engineering thermoplastics. Crystallization rate as a function of temperature controls the optimum mold temperature and cycle time of the process. It is desirable to operate at mold temperatures less than 110° C. because this allows for the use of traditional water heated, as opposed to oil heated, molds. These low mold temperatures also allow the process to operate at an optimum crystallization rate, which in turn translates into shorter cycle times and improved economies.
The use of a plasticizer is well known to the art to enhance crystallization rate. A plasticizer typically decreases the melt viscosity and depresses the glass transition temperature of the thermoplastic, which in turn increases crystallization rate at a lower temperature. Common plasticizers for polyester engineering plastics are low molecular weight organic esters such as neopentylglycoldibenzoate (Benzoflex S312) and dipropyleneglycoldienzoate (Benzoflex 9-88). Alternate plasticizers are poly(ether esters) such as copolyesters of poly(butylene terephthalate) and poly(tetramethylene glycol) (Hytrel).
Another key requirement when processing polyesters is drying. It is important to minimize or eliminate moisture from a polyester prior to melt processing, otherwise hydrolytic degradation occurs resulting in a diminished molecular weight and unacceptable mechanical properties. Furthermore, because drying results in an increased processing cost it is important to minimize the drying time required. Thus it is an advantage to dry at higher temperatures as this reduces the time necessary. However, many of the plasticizers and flow aids used in the art are volatile under drying conditions. Volatile emissions are undesirable because they contaminate the dryers and increase cleaning and maintenance costs.
Low molecular weight organic esters are known plasticizers for polyesters, but they tend to be volatile in the dryers, which can be remedied only by lowering drying temperatures and increasing drying time. Increasing the molecular weight of organic esters is known to reduce volatility during drying, however it is taught that this approach is not effective because the higher molecular organic esters are no longer plasticizers.
Low volatility has previously been considered advantageous because it allows higher temperatures and shorter times for melt processing. Poly(alkylene ether)s have been reported to be such non-volatile processing aids for polyesters. Suprisingly, however, many of these non-volatile poly(alkylene ether)s are volatile during the drying process over the relatively long times required for drying. This volatility results in contaminated dryers and loss of productivity.
SUMMARY OF THE INVENTION
This invention pertains to the use of a specified molecular weight range of poly(alkylene ether)s, such as poly(ethylene glycol) (PEG), poly(tetramethylene glycol) (PTMG), and poly(propylene glycol) (PPG), and end-capped poly(alkylene ether)s, as plasticizers for polyesters such as poly(ethylene terephthalate) (PET), poly(propylene terephthalate) (PPT), poly(butylene terephthalate) (PEBT), poly(ethylene naphthalate) (PEN), and poly(1,4-cyclohexanedimethylene terephthalate) (PCT), that are non-volatile during drying processes as well as during melt processing. Such poly(alkylene ether)s and end-capped poly(alkylene ether)s decrease the melt viscosity of the polymer matrix and depress the glass transition temperature, and thereby improve the processability of polyesters.
Thus, in accordance with the purpose(s) of this invention, as embodied and broadly described herein, this invention, in one aspect, relates to a blend comprising:
a. from about 1 to about 25 weight pphr of a poly(alkylene ether) having the formula (I):
wherein:
i. m is an integer of from 1 to 3;
ii. n is an integer of from 5 to 140;
iii. X is selected from hydrogen, hydrocarbon, and amide of 10 carbons or less;
iv. A and B are independently selected from alkyl, acyl, or an aryl residue, of 1 to 200 carbons;
v. the poly(alkylene ether) has a number average molecular weight of from about 800 to about 6000; and
b. a polyester resin selected from modified and unmodified poly(ethylene terephthalate), poly(propylene terephthalate), poly(butylene terephthalate), poly(ethylene naphthalate), and poly(1,4-cyclohexanedinethylene terephthalate), wherein:
i. the polyester is semicrystalline; and
ii. the polyester has a melting point greater than 200° C.
In another embodiment the invention provides a blend comprising:
a. from about 1 to about 25 weight pphr of a poly(alkylene ether) having the formula (I) wherein:
i. m is 1;
ii. n is an integer of from 10 to 25;
iii. X is selected from hydrogen, methyl, ethyl, and propyl;
iv. A and B are independently selected from alkyl, acyl, or an aryl residue, of 1 to 200 carbons;
v. the number average molecular weight of A and B summed is greater than about 250; and
vi. the poly(alkylene ether) has a number average molecular weight of from about 800 to about 6000; and
b. a polyester resin selected from modified and unmodified poly(ethylene terephthalate), poly(propylene terephthalate), poly(butylene terephthalate), poly(ethylene naphthalate), and poly(1,4-cyclohexanedimethylene terephthalate), wherein:
i. the polyester is semicrystalline; and
ii. the polyester has a melting point greater than 240° C.
In another embodiment the invention provides a process for making a composition comprising melt mixing a blend comprising:
a. from about 1 to about 25 weight pphr of a poly(alkylene ether) having the formula (I) wherein:
i. m is an integer of from 1 to 3;
ii. n is an integer of from 5 to 140;
iii. X is selected from hydrogen, hydrocarbon, and amide of 10 carbons or less;
iv. A and B are independently selected from alkyl, acyl, or an aryl residue, of 1 to 200 carbons;
v. the poly(alkylene ether) has a number average molecular weight of from about 800 to about 6000; and
b. a polyester resin selected from modified and unmodified poly(ethylene terephthalate), poly(propylene terephithalate), poly(butylene terephthalate), poly(ethylene naphthalate), and poly(1,4-cyclohexanedimethylene terephthalate), wherein:
i. the polyester is semicrystalline; and
ii. the polyester has a melting point greater than 200° C.;
wherein the melt mixing is performed under sufficiently mild conditions to avoid reaction between the polyester and the poly(alkylene ether).
In still another embodiment the invention provides a process for making a composition comprising melt mixing a blend comprising:
a. from about 1 to about 25 weight pphr of a poly(alkylene ether) having the formula (I) wherein:
i. m is 1;
ii. n is an integer of from 10 to 25;
iii. X is selected from hydrogen, methyl, ethyl, and propyl;
iv. A and B are independently selected from alkyl, acyl, or an aryl residue, of 1 to 200 carbons;
v. the number average molecular weight of A and B summed is greater than about 250; and
vi. the poly(alkylene ether) has a number average molecular weight of from about 800 to about 6000; and
b. a polyester resin selected from modified and unmodified poly(ethylene terephthalate), poly(propylene terepthalate), poly(butylene terephthalate), poly(ethylene naphthalate), and poly(1,4-cyclohexanedimethylene terephthalate), wherein:
i. the polyester is semicrystalline; and
ii. the polyester has a melting point greater than 240° C.
wherein the melt mixing is performed under sufficiently mild conditions to avoid reaction between the polyester and the poly(alkylene ether)
In still another embodiment the invention provides a method of using polyester blends to reduce volatile emissions during drying, comprising providing a polyester blend of this invention, and drying the polyester blend at gre
Bell Bruce C.
Brink Andrew E.
Keep Gerald T.
Eastman Chemical Company
Gwinnell Harry
Tubach Cheryl
Tudor Harold J.
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