Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
2001-01-17
2003-08-19
Boykin, Terressa M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From phenol, phenol ether, or inorganic phenolate
C528S198000
Reexamination Certificate
active
06608163
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention belongs to the field of polycarbonates. In particular, it relates to polycarbonate copolymers having improved solvent resistance, improved hydrolytic stability, or combinations thereof.
Polycarbonates in general are prepared from dihydric phenol compounds and carbonic acid derivatives. For example, one important polycarbonate can be prepared via melt polymerization of diphenyl carbonate and Bisphenol A. The reaction is conducted at high enough temperatures for the starting monomers and product to remain molten, while the reactor pressure is staged in order to effectively remove phenol, the by-product of the polycondensation reaction.
Condensation polymers such as the polycarbonates are susceptible to hydrolytic degradation, especially under certain environmental exposures. In particular, when polycarbonate is utilized as an internal structural component in dishwashers, the polycarbonate material is regularly exposed to dilute caustic solution, which has deleterious effects on the polymer structure over time. Further, many polycarbonates are utilized in applications which involve exposure to organic solvents.
Thus, a need exists for polycarbonates having improved hydrolytic stability, especially against dilute caustic solution as well as resistance to organic solvents.
SUMMARY OF THE INVENTION
The present invention provides polycarbonate copolymers having improved hydrolytic stability, solvent resistance, or combinations thereof. In particular, certain of the copolymers of the invention have improved resistance to dilute caustic solution, while others show improved solvent resistance. Thus, the copolymers of the present invention are particularly useful as structural elements in applications where such elements routinely come in contact with caustic solutions, such as in automatic dishwashing equipment. Preferred comonomers include 4,4′-biphenol, bis-(4-dihydroxyphenyl)terephthalamide (“BHPT”), and a bisimide bisphenol obtained by reacting Bisphenol A dianhydride (BPADA) with 4,4′-isopropylidene phenol aniline. The comonomers are utilized along with 2,2-bis(4-hydroxyphenyl)propane (Bisphenol A) in concentrations in a range between about 1 weight percent and about 50 weight percent of repeating units in the polycarbonate based on total dihydric phenol.
DETAILED DESCRIPTION OF THE INVENTION
In this application:
The singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstances may or may not occur, and that description includes instances where the event or circumstance occurs and instances where it does not.
“BPA” is herein defined as Bisphenol A or 2,2-bis(4-hydroxyphenyl)propane.
Unless otherwise stated, “weight percent” in reference to the composition of a polycarbonate in this specification is based upon 100 weight percent of the repeating units of the polycarbonate. For instance, “a polycarbonate comprising 90 weight percent of BPA” refers to a polycarbonate in which 90 weight percent of the repeating units are residues derived from Bisphenol A or its corresponding derivative(s). Corresponding derivatives include, but are not limited to, corresponding oligomers of the diphenols; corresponding esters of the diphenol and their oligomers; and the corresponding chloroformates of the diphenol and their oligomers.
Thus, in one aspect, the present invention provides a polycarbonate comprised of residues of;
(a) a diester compound; and
(b) a dihydric phenol compound, wherein said dihydric phenol compound(s) are comprised of
(i) 2,2-bis(4-hydroxyphenyl) propane;
(ii) at least one comonomer in a range between about 1 weight percent and about 50 weight percent of the repeating units in the polycarbonate, comprising bis-(4-hydroxyphenyl)-terephthalamide, bis-(3-hydroxyphenyl)terephthalamide, a compound of the formula
wherein X is a divalent aromatic moiety; and
(iii) optionally, dihydric phenol compounds in addition to those in (i) and (ii).
The polycarbonate is formed via a polycondensation reaction.
Examples of divalent groups (X) include phenylene, naphthalene, and groups of the formula
(i.e., “Bisimide BPA” or BIABPA) as well as such groups optionally substituted by one or more groups selected from C
1
-C
8
alkyl, C
1
-C
8
alkoxy, halo, nitro, and the like.
The utilization of the above monomers provides, in certain cases, improved hydrolytic stability to the polycarbonate compositions and in certain cases improved solvent resistance. In an alternate embodiment of the present invention, the monomers in paragraph (ii) above are utilized in proportions in a range between about 1 weight percent and about 40 weight percent of the repeating units in the polycarbonate with no greater than 15 weight percent of any one given comonomer. In a further alternate embodiment of the present invention, the monomers in paragraph (ii) above are utilized in a range between about 1 weight percent and about 5 weight percent of the repeating units in the polycarbonate. In this regard, the use of the term “residue” denotes that portion of the molecule or moiety which remains after the polycondensation reaction has taken place.
The structure of bis-(4-hydroxyphenyl)terephthalamide and bis-(3-hydroxyphenyl)terephthalamide (BHFF) are as follows, respectively:
Certain combinations of comonomers result in melt phase-produced polycarbonates having improved hydrolytic stability. In particular, when the comonomers illustrated above in this first aspect of the present invention are utilized with 4,4′-biphenol, hexafluoro Bisphenol A, or combinations thereof, the resulting polycarbonates exhibit improved hydrolytic stability. Thus, in a typical embodiment of this first aspect of the present invention, there is provided the polycarbonates of the first aspect, further comprising at least one comonomer selected from 4,4′-biphenol and a compound of the formula
In a typical embodiment of the present invention, the 4,4′-biphenol, hexafluoro Bisphenol A, or combinations thereof, are utilized in an amount in a range between about 1 weight percent and about 15 weight percent of the repeating units in the polycarbonate.
4,4′-Biphenol alone as a comonomer in conjunction with Bisphenol A in a melt phase-produced polycarbonate is useful in effecting an increase in hydrolytic stability. Thus, in a second aspect of the present invention, there is provided a polycarbonate comprised of residues of;
(a) a diester compound; and
(b) a dihydric phenol compound, wherein said dihydric phenol compound(s) are comprised of
(i) 2,2-bis(4-hydroxyphenyl) propane; and
(ii) 4,4′-biphenol in a range between about 1 weight percent and about 30 weight percent of the repeating units in the polycarbonate.
In this regard, 4,4′-biphenol is commonly in an amount in a range between about 1 weight percent and about 15 weight percent of the repeating units in the polycarbonate.
4,4′-Biphenol, when utilized with certain other comonomers, results in improved hydrolytic stability in melt phase-produced polycarbonates. Thus, in third aspect, the present invention provides a polycarbonate comprised of residues of;
(a) a diester compound; and
(b) a dihydric phenol compound, wherein said dihydric phenol compound(s) are comprised of
(i) 2,2-bis(4-hydroxyphenyl) propane; and
(ii) comonomers in a range between about 1 weight percent and about 50 weight percent of the repeating units in the polycarbonate, comprising 4,4′-biphenol and a compound of the formula
wherein X is a group of the formula
wherein the proportion of 4,4′-biphenol is in a range between about 1 weight percent and about 15 weight percent of the repeating units in the polycarbonate.
BIABPA, when utilized as a comonomer in a melt phase-produced polycarbonate, provides improved hydrolytic stability. Thus, in a fourth aspect of the present invention, there is provided a polycarbonate comprised of residues of;
(a) a diester compound; and
(b) a dihydric p
Bailly Christian Maria Emile
Siclovan Tiberiu Mircea
Bennett Bernadette M.
Boykin Terressa M.
General Electric Company
Johnson Noreen C.
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