Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From phenol – phenol ether – or inorganic phenolate
Reexamination Certificate
1999-10-12
2003-05-06
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
06559270
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to resinous compositions of matter, and more specifically to block copolyestercarbonates having improved weatherability.
Polycarbonates and polyesters, especially poly(alkylene dicarboxylates), and blends thereof are widely employed classes of polymers, in part because of their excellent physical properties including high impact strength. However, their long term color instability is a problem. It causes yellowing, detracting from the transparency and attractiveness of the polymers. Loss of gloss can also be an undesirable long term phenomenon.
Yellowing of polycarbonates and polyesters is caused largely by the action of ultraviolet radiation, which is why such yellowing is frequently designated “photoyellowing”. Numerous means for suppressing photoyellowing have been employed and proposed. Many of these involve incorporation in the polycarbonate of ultraviolet absorbing compounds (UVA's). For the most part, UVA's are low molecular weight compounds and they must be employed at relatively low levels, typically up to 1% by weight, to avoid degradation of the physical properties of the polymer such as impact strength and high temperature properties as reflected in heat distortion temperature.
Other polymers have been blended with polycarbonates and/or polyesters to improve their resistance to degradation by ultraviolet radiation and loss of gloss, hereinafter sometimes collectively designated “weatherability”. Examples of blends of this type are weatherable blends of polycarbonates with copolyesters comprising resorcinol iso/terephthalate units, optionally in combination with “soft block” ester units derived, for example, from an aliphatic or alicyclic dihydroxy compound or dicarboxylic acid. However, such blends are typically immiscible and their use is, therefore, limited to situations in which transparency is not required. In addition, it is of interest to produce a wider variety of weatherable and weatherability-improving polymers.
Japanese Kokai 56/133,332 describes copolyestercarbonates “having a highly alternating orientation”. They are prepared by a 2-step process in which the first step is preparation of a hydroxy-terminated polyester oligomer having a degree of polymerization of 1-2. The second step is treatment of said oligomer with a carbonate precursor such as phosgene to afford a final product having essentially alternating polyester and polycarbonate linkages; i.e., the degree of polymerization of the carbonate blocks is also about 1-2. These copolyestercarbonates are alleged to have excellent heat resistance, solvent resistance and moldability. No details of their weatherability are provided.
SUMMARY OF THE INVENTION
The present invention is based on the discovery of a class of block copolyestercarbonates having excellent weatherability. Blends of said copolyestercarbonates with other polymers, specifically polycarbonates and polyesters, are resistant to loss of gloss and have excellent physical properties.
One aspect of the invention, therefore, is block copolyestercarbonates comprising organic carbonate blocks alternating with arylate blocks, said arylate blocks comprising arylate structural units derived from at least one 1,3-dihydroxybenzene moiety and at least one aromatic dicarboxylic acid, and having a degree of polymerization of at least about 4.
Another aspect of the invention is block copolymers comprising moieties of the formula
wherein each R
1
is independently halogen or C
1-4
alkyl, each R
2
is independently a divalent organic radical, p is 0-3, m is at least about 3 and n is at least about 4.
Another aspect is compositions comprising resinous blends of block copolyestercarbonates as described above with at least one other polymer selected from the group consisting of polycarbonates, poly(alkylene dicarboxylates), polyarylates, polyetherimides, and addition polymers, and any reaction products of said blends.
Still another aspect is a method for preparing block copolyestercarbonates which comprises the steps of:
(A) preparing a hydroxy-terminated polyester intermediate having a degree of polymerization of at least 4 by the reaction of at least one 1,3-dihydroxybenzene moiety with at least one aromatic dicarboxylic acid dichloride under alkaline conditions; and
(B) conducting a reaction of said polyester intermediate with a carbonate precursor.
DETAILED DESCRIPTION; PREFERRED EMBODIMENTS
In one embodiment the present invention comprises block copolyestercarbonates which comprise alternating carbonate and arylate blocks. They include polymers comprising structural units of the formula
wherein each R
1
is independently halogen or C
1-12
alkyl, p is 0-3, each R
2
is independently a divalent organic radical, m is at least 1 and n is at least about 4. Preferably n is at least about 10, more preferably at least about 20 and most preferably about 30-150. Preferably m is at least about 3, more preferably at least about 10 and most preferably about 20-200. In especially preferred embodiments m is between about 20 and 50. Within the context of the invention “alternating carbonate and arylate blocks” means that the copolyestercarbonates comprise at least one carbonate block and at least one arylate block.
The arylate blocks contain structural units comprising 1,3-dihydroxybenzene moieties which may be unsubstituted or substituted. Alkyl substituents, if present, are preferably straight-chain or branched alkyl groups, and are most often located in the ortho position to both oxygen atoms although other ring locations are contemplated. Suitable C
1-12
alkyl groups include methyl, ethyl, n-propyl, isopropyl, butyl, iso-butyl, t-butyl, nonyl, decyl, and aryl-substituted alkyl, including benzyl, with methyl being particularly preferred. Suitable halogen substituents are bromo, chloro, and fluoro. 1,3-Dihydroxybenzene moieties containing a mixture of alkyl and halogen substituents are also suitable. The value for p may be 0-3, preferably 0-2, and more preferably 0-1. A preferred 1,3-dihydroxybenzene moiety is 2-methylresorcinol. The most preferred 1,3-dihydroxybenzene moiety is unsubstituted resorcinol in which p is zero. Polymers containing mixtures of 1,3-dihydroxybenzene moieties, such as a mixture of unsubstituted resorcinol with 2-methylresorcinol are also contemplated.
In the arylate structural units said 1,3-dihydroxybenzene moieties are bound to aromatic dicarboxylic acid moieties which may be monocyclic moieties, such as isophthalate or terephthalate or their chlorine-substituted derivatives; or polycyclic moieties, such as biphenyl dicarboxylate, diphenylether dicarboxylate, diphenylsulfone dicarboxylate, diphenylketone dicarboxylate, diphenylsulfide dicarboxylate, or naphthalenedicarboxylate, preferably naphthalene-2,6-dicarboxylate; or mixtures of monocyclic and/or polycyclic aromatic dicarboxylates. Preferably, the aromatic dicarboxylic acid moieties are isophthalate and/or terephthalate. Either or both of said moieties may be present. For the most part, both are present in a molar ratio of isophthalate to terephthalate in the range of about 0.25-4.0:1. When the isophthalate to terephthalate ratio is greater than about 4.0:1, then unacceptable levels of cyclic oligomer may form. When the isophthalate to terephthalate ratio is less than about 0.25:1, then unacceptable levels of insoluble polymer may form. Preferably the molar ratio of isophthalate to terephthalate is about 0.4-2.5:1, and more preferably about 0.67-1.5:1.
In the carbonate blocks, each R
2
is independently an organic radical derived from a dihydroxy compound. For the most part, at least about 60 percent of the total number of R
2
groups in the polymer are aromatic organic radicals and the balance thereof are aliphatic, alicyclic, or aromatic radicals. Suitable R
2
radicals include m-phenylene, p-phenylene, 4,4′-biphenylene, 4,4′-bi(3,5-dimethyl)-phenylene, 2,2-bis(4-phenylene)propane and similar radicals such as those which correspond to the dihydroxy-substituted aromatic hydrocarbons disclosed by name or for
Blohm Margaret Louise
Brown Sterling Bruce
Brunelle Daniel Joseph
Buckley, Jr. Donald Joseph
Fishburn Georgia Dris
Boykin Terressa M.
Brown S. Bruce
General Electric Company
Johnson Noreen C.
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