An improved hydrolytically stable aromatic polyester-carbonate composition comprising in admixture an aromatic polyester-carbonate resin and a hydrolytically stabilizing amount of at least one stabilizing compound selected from epoxy silanes and epoxy siloxanes.

BACKGROUND OF THE INVENTION 
Polyester-carbonates are well known high molecular weight thermoplastic 
materials which exhibit many advantageous properties. These properties 
render the polyester-carbonate resins useful as high performance 
engineering materials. 
However, one of the significant problems associated with the use of 
polyester-carbonate resins, particularly in high temperature environments, 
is the tendency of polyester-carbonates to undergo hydrolytic degradation. 
It is known in the prior art that the addition of certain additives to 
plastics, such as polycarbonates, results in compositions exhibiting 
increased resistance to hydrolytic degradation. Examples of such additives 
are found in U.S. Pat. Nos. 3,839,247; 4,076,686 and 4,138,379. These 
additives are generally quite useful, and have extended the uses of 
plastics, such as aromatic polycarbonates, into areas requiring increased 
levels of hydrolytic stability. However, certain properties of plastics, 
e.g., polycarbonate resins, can be detrimentally affected by the addition 
of these additives. Thus, in the case of aromatic polycarbonate resins, 
the presence of these additives can bring about haze in the polycarbonate 
article or detrimentally affect the color of the polycarbonate article. 
There thus exists a need for polyester-carbonate compositions which exhibit 
improved hydrolytic stability while at the same time retaining all of the 
advantageous properties of unmodified polyester-carbonate resins. It is an 
object of the instant invention to provide such a polyester-carbonate 
composition. 
SUMMARY OF THE INVENTION 
In accordance with the present invention there are provided novel high 
molecular weight aromatic polyester-carbonate compositions which exhibit 
improved resistance to hydrolytic degradation comprising in admixture 
aromatic polyester-carbonate resin and a stabilizing amount of at least 
one hydrolytic stabilizer selected from epoxy silanes, epoxy siloxanes, 
and mixtures thereof. 
DESCRIPTION OF THE INVENTION 
It has now been found that polyester-carbonate resin compositions can be 
obtained whose physical properties permit them to be used in a broader 
range of applications than was previously possible. This is accomplished 
by admixing the polyester-carbonate resin with a stabilizing amount of an 
epoxy compound selected from epoxy silanes, epoxy siloxanes, and mixtures 
thereof. These stabilized compositions can be utilized in higher 
temperature and higher moisture environments than heretofore available 
polyester-carbonate resin compositions. 
The preparation of polyester-carbonates which may be employed in the 
compositions of the present invention is described in U.S. Pat. Nos. 
3,030,331; 3,169,121; 3,207,814; 4,194,038 and 4,156,069, as well as in 
copending application Ser. No. 33,389 filed Apr. 26, 1978 and assigned to 
the same assignee as the instant application, all of which are 
incorporated herein by reference. 
The polyester-carbonates can generally be described as copolyesters 
containing carbonate groups, carboxylate groups and aromatic carbocyclic 
groups in the polymer chain, in which at least some of the carboxylate 
groups and at least some of the carbonate groups are bonded directly to 
ring carbon atoms of the aromatic carbocyclic groups. These 
polyester-carbonates are, in general, prepared by reacting a difunctional 
carboxylic acid or a reactive derivative of the acid such as the acid 
dihalide, a dihydric phenol and a carbonate precursor. 
The dihydric phenols useful in formulating the polyester-carbonates useful 
in the compositions of the present invention are in general represented by 
the general formula 
##STR1## 
in which A represents an aromatic group such as phenylene, biphenylene, 
naphthylene, etc. E may be an alkylene or alkylidene group such as 
methylene, ethylene, propylene, propylidene, isopropylidene, butylene, 
butylidene, isobutylidene, amylene, isoamylene, amylidene, isoamylidene, 
etc. Where E is an alkylene or alkylidene group, it may also consist of 
two or more alkylene or alkylidene groups connected by a non-alkylene or 
non-alkylidene group such as an aromatic linkage, a tertiary amino 
linkage, an ether linkage, a carbonyl linkage, a silicon containing 
linkage, or by a sulfur containing linkage such as a sulfide, sulfoxide, 
sulfone, etc. In addition, E may be a cycloaliphatic group (e.g., 
cyclopentyl, cyclohexyl, etc.); a sulfur containing linkage such as 
sulfide, sulfoxide or sulfone; an ether linkage; a carbonyl group; a 
tertiary nitrogen group or a silicon containing linkage such as a silane 
or a siloxy group. The symbol R in Formula I represents hydrogen or a 
monovalent hydrocarbon group such as alkyl (e.g., methyl, ethyl, propyl, 
etc.). aryl (e.g., phenyl, naphthyl, etc.), aralkyl (e.g., benzyl, 
ethylphenyl, etc.), alkaryl, or a cycloaliphartic group (e.g., 
cyclopentyl, cyclohexyl, etc.). Y may be an inorganic atom such as a 
halogen (fluorine, chlorine, bromine, iodine), an inorganic group such as 
the nitro group, an organic group such as R above, or an oxy group such as 
OR, it being only necessary that Y be inert to and unaffected by the 
reactants and the reaction conditions. The letter m represents any integer 
from and including zero through the number of positions on A available for 
substitution; p represents an integer from and including zero through the 
number of positions on E available for substitution; t represents an 
integer equal to at least one; s is either zero or one; and u represents 
an integer including zero. 
In the dihydric phenol compound represented by Formula I above, when more 
than one Y substituent is present, they may be the same or different. The 
same holds true for the R substituent. Where s is zero in Formula I and u 
is not zero, the aromatic rings are joined with no intervening alkylene or 
other bridge. The positions of the hydroxyl groups and Y on the aromatic 
nuclear residues A can be varied in the ortho, meta or para positions and 
the groupings can be in a vicinal, asymmetrical or symmetrical 
relationship, where two or more ring carbon atoms of the aromatic 
hydrocarbon residue are substituted with Y and a hydroxyl group. 
Some nonlimiting examples of compounds falling within the scope of Formula 
I include: 
2,2-bis(4-hydroxyphenyl)propane (bisphenol A); 
2,4'-dihydroxydiphenylmethane; 
bis(2-hydroxyphenyl)methane; 
bis(4-hydroxyphenyl)methane; 
bis(4-hydroxy-5-nitrophenyl)methane; 
bis(4-hydroxy-2,6-dimethyl-3-methoxyphenyl)methane; 
1,1-bis(4-hydroxyphenyl)ethane; 
1,1-bis(4-hydroxy-2-chlorophenyl)ethane; 
2,2-bis(3-phenyl-4-hydroxyphenyl)propane; 
bis(4-hydroxyphenyl)cyclomethane; and 
2,2-bis(4-hydroxyphenyl)-1-phenylpropane. 
These dihydric phenols may be used individually or as mixtures of two or 
more different dihydric phenols. 
In general any difunctional carboxylic acid, or its reactive derivative 
such as the acid dihalide, conventionally used in the preparation of 
polyesters may be used for the preparation of polyester-carbonates useful 
in formulating the compositions of the present invention. In general the 
carboxylic acids which may be used include the aliphatic carboxylic acids, 
aliphatic-aromatic carboxylic acids, or aromatic carboxylic acids. The 
aromatic dicarboxylic acids or their reactive derivatives such as the 
aromatic diacid halides are preferred as they produce the aromatic 
polyestercarbonates which are most useful, from the standpoint of physical 
properties, in the practice of the instant invention. 
These carboxylic acids may be represented by the general formula 
##STR2## 
wherein R.sup.1 represents an alkylene, alkylidene or cycloaliphatic group 
in the same manner as set out above for E in Formula I; an alkylene, 
alkylidene or cycloaliphatic group containing ethylenic unsaturation; an 
aromatic radical such as phenylene, naphthylene, biphenylene, substituted 
phenylene, etc.; two or more aromatic groups connected through 
non-aromatic linkages such as those defined by E in Formula I; or a 
divalent aliphatic-aromatic hydrocarbon radical such as an aralkyl or 
alkaryl radical. R.sup.2 is either a carboxyl or a hydroxyl group. The 
letter q represents the integer one where R.sup.2 is a hydroxyl group and 
either zero or one where R.sup.2 is a carboxyl group. Thus the 
difunctional carboxylic acid will either be a monohydroxy monocarboxylic 
acid or a dicarboxylic acid. For purposes of the present invention the 
aromatic dicarboxylic acids or their reactive derivatives such as, for 
example, the acid dihalides, are preferred. Thus in these preferred 
aromatic dicarboxylic acids, as represented by Formula II, R.sup.2 is a 
carboxyl group and R.sup.1 is an aromatic radical such as phenylene, 
biphenylene, naphthylene, substituted phenylene, etc.; two or more 
aromatic groups connected through non-aromatic linkages; or a divalent 
aliphatic-aromatic radical. Some nonlimiting examples of suitable 
preferred aromatic dicarboxylic acids which may be used in preparing the 
polyester-carbonate resins of the instant invention include phthalic acid, 
isophthalic acid, terephthalic acid, homophthalic acid, o-, m-, and 
p-phenylenediacetic acid, the polynuclear aromatic acids such as diphenic 
acid, and 1,4-naphthalic acid. 
These acids may be used individually or as mixtures of two or more 
different acids. 
The carbonate precursor may be either a carbonyl halide, a carbonate ester, 
or a haloformate. The carbonyl halides which can be employed herein are 
carbonyl chloride and carbonyl bromide. Typical of the carbonate esters 
which may be employed herein are diphenyl carbonate, 
di(halophenyl)carbonates such as di(chlorophenyl)carbonate, 
di(bromophenyl)carbonate, di(trichlorophenyl)carbonate, 
di(tribromophenyl)carbonate, etc, di(alkylphenyl)carbonates such as 
di(tolyl)carbonate, etc., di(naphthyl)carbonate, 
di(chloronaphthyl)carbonate, phenyltolyl carbonate, chloronaphthyl 
chlorophenyl carbonate, and the like. The haloformates suitable for use 
herein include bis-haloformates of dihydric phenols such as 
bis-chloroformates of hydroquinone, etc. or glycols such as 
bis-haloformates of ethylene glycol, neopentyl glycol, polyethylene 
glycol, etc. While other carbonate precursor will occur to those skilled 
in the art, carbonyl chloride, also known as phosgene, is preferred. 
The polyester-carbonates which are useful in the practice of the present 
invention include the aromatic polyester-carbonates derived from dihydric 
phenols, aromatic dicarboxylic acids or their reactive derivatives such as 
the aromatic diacid halides, and phosgene. A quite useful class of 
aromatic polyester-carbonates is that derived from bisphenol A; 
isophthalic acid, terephthalic acid, or a mixture of isophthalic acid and 
terephthalic acid, or the reactive derivatives of these acids such as 
terephthaloyl dichloride, isophthaloyl dichloride, or a mixture of 
isophthaloyl dichloride and terephthaloyl dichloride; and phosgene. When a 
mixture of isophthalic acid and terephthalic acid or isophthaloyl 
dichloride and terephthaloyl dichloride is used the mixture contains these 
two components in a ratio, by weight, of from 5:95 to 95:5. 
The polyester-carbonate compositions of the instant invention are 
formulated by admixing the particular epoxy compound described hereinafter 
with the polyester carbonate resin. The epoxy compound may be used 
individually or as a mixture of two or more different epoxy compounds. The 
epoxy stabilizing compound is selected from the group consisting of epoxy 
silanes and epoxy siloxanes. 
The epoxy silanes useful as hydrolytic stabilizers in the compositions of 
the present invention are compounds represented by the general formula 
EQU Z.sub.n Si(R.sup.3).sub.4-n III 
wherein n is an integer having a value of from 1 to 3 inclusive. In Formula 
III R.sup.3 is independently selected from hydrogen; alkyl radicals; 
substituted alkyl radicals; cycloalkyl radicals; alkenyl radicals; aryl 
radicals; aralkyl radicals; alkaryl radicals; divalent organic radicals 
which together with the Si atom form a cyclic structure, such organic 
radicals being selected from divalent saturated aliphatic hydrocarbon 
radicals and divalent saturated organic radicals containing carbon and 
oxygen atoms in the ring structure, with the proviso that if one of 
R.sup.3 is such a divalent organic radical then n has a value of 1 or 2 
and the total valence of silicon is four; OR.sup.4 radicals wherein 
R.sup.4 is selected from hydrogen, alkyl radicals, substituted alkyl 
radicals, alkenyl radicals, aryl radicals, aralkyl radicals, and alkaryl 
radicals; --R.sup.5 OR.sup.4 radicals wherein R.sup.5 is a divalent 
saturated aliphatic hydrocarbon radical or a divalent aromatic hydrocarbon 
radical; --OOCR.sup.4 radicals; --COOR.sup.4 radicals; --R.sup.5 
COOR.sup.4 radicals; --R.sup.5 OOCR.sup.4 radicals; and polyether radicals 
of the general formula --R.sup.6 --(--O--R.sup.7 --).sub.a --O--R.sup.8 
wherein a is an integer having a value of from 1 to 4 inclusive, R.sup.6 
and R.sup.7 are independently selected from divalent saturated aliphatic 
hydrocarbon radicals, and R.sup.8 is an alkyl radical. 
Preferably R.sup.3 is selected from hydrogen; hydroxyl; alkyl radicals; 
alkoxy radicals; aryl radicals; aryloxy radicals; alkaryl radicals; and 
aralkyl radicals. 
In Formula III preferred alkyl and substituted alkyl radicals represented 
by R.sup.3 and R.sup.4 are those containing from 1 to about 24 carbon 
atoms. Preferred cycloalkyl radicals represented by R.sup.3 are those 
containing from 4 to about 24 carbon atoms. Preferred alkenyl radicals 
represented by R.sup.3 and R.sup.4 are those containing from 2 to about 24 
carbon atoms. Preferred aryl radicals represented by R.sup.3 and R.sup.4 
are those containing from 6 to 24 carbon atoms. Preferred alkaryl and 
aralkyl radicals represented by R.sup.3 and R.sup.4 are those containing 
from 7 to about 24 carbon atoms. Preferred divalent saturated aliphatic 
hydrocarbon radicals which together with the Si atom form a cyclic 
structure, as represented by R.sup.3, are those containing from 2 to about 
24 carbon atoms; while preferred divalent saturated organic radicals 
containing carbon and oxygen atoms in the ring structure are those 
containing from 2 to about 24 carbon atoms and from 1 to about 6 oxygen 
atoms. Preferred divalent saturated aliphatic hydrocarbon radicals 
represented by R.sup.5, R.sup.6 and R.sup.7 are those containing from 1 to 
about 12 carbon atoms. Preferred alkyl radicals represented by R.sup.8 are 
those containing from 1 to about 12 carbon atoms. 
In Formula III Z represents a monovalent epoxy group selected from the 
class consisting of monovalent derivatives of epoxy ethane and the 
monovalent derivatives of epoxy cyclohexane. 
The monovalent derivatives of epoxy ethane are represented by the general 
formula 
##STR3## 
wherein: 
(i) R.sup.9, R.sup.10, R.sup.11 and R.sup.12 are independently selected 
from hydrogen; alkyl radicals; substituted alkyl radicals; cycloalkyl 
radicals; alkenyl radicals; aryl radicals; aralkyl radicals; alkaryl 
radicals; OR.sup.13 radicals wherein R.sup.13 is selected from the class 
consisting of hydrogen, alkyl radicals, substituted alkyl radicals, 
alkenyl radicals, aryl radicals, alkaryl radicals, and aralkyl radicals; 
--R.sup.14 OR.sup.13 radicals wherein R.sup.14 is a divalent saturated 
aliphatic hydrocarbon radical or a divalent aromatic hydrocarbon radical; 
--OOCR.sup.13 radicals; --COOR.sup.13 radicals; --R.sup.14 OOCR.sup.13 
radicals; --R.sup.14 COOR.sup.13 radicals; --OR.sup.15 radicals wherein 
R.sup.15 is selected from the group consisting of oxirane ring containing 
monovalent saturated aliphatic hydrocarbon radicals and oxirane ring 
containing monovalent aliphatic-aromatic hydrocarbon radicals; --R.sup.14 
OR.sup.15 radicals; --OOCR.sup.15 radicals; --COOR.sup.15 radicals; 
--R.sup.14 OOCR.sup.15 radicals; and --R.sup.14 COOR.sup.15 radicals; with 
the proviso that 
(ii) one of R.sup.9, R.sup.10, R.sup.11 or R.sup.12 is selected from the 
class consisting of divalent saturated aliphatic hydrocarbon radicals; 
divalent aromatic hydrocarbon radicals; --OR.sup.16 -- radicals wherein 
R.sup.16 is a divalent saturated aliphatic hydrocarbon radical or a 
divalent aromatic hydrocarbon radical; --R.sup.14 OR.sup.16 -- radicals; 
--OOCR.sup.16 -- radicals; --COOR.sup.16 -- radicals; --R.sup.14 
OOCR.sup.16 -- radicals; and --R.sup.14 COOR.sup.16 -- radicals. 
Preferred derivatives of epoxy ethane represented by Formula IV are those 
wherein: 
(i) R.sup.9 through R.sup.12 are independently selected from the class 
consisting of hydrogen; alkyl radicals; substituted alkyl radicals; 
cycloalkyl radicals; aryl radicals; aralkyl radicals; alkaryl radicals; 
and OR.sup.17 radicals wherein R.sup.17 is selected from the class 
consisting of hydrogen, alkyl radicals, substituted alkyl radicals, aryl 
radicals, alkaryl radicals, and aralkyl radicals; with the proviso that 
(ii) one of R.sup.9, R.sup.10, R.sup.11 or R.sup.12 is selected from the 
class consisting of divalent saturated aliphatic hydrocarbon radicals; 
divalent aromatic hydrocarbon radicals; OR.sup.16 -- radicals; and 
--R.sup.14 OR.sup.16 -- radicals. 
While in Formula IV R.sup.10 is shown as falling within the definition of 
(ii) and being bonded to the silicon atom, this is merely done for the 
sake of convenience, clarity and illustration, and it is to be understood 
that any one of R.sup.9 through R.sup.12 can fall within the definition of 
(ii) and be bonded to the silicon atom. 
In Formula IV preferred alkyl and substituted alkyl radicals represented by 
R.sup.9 --R.sup.13 and R.sup.17 are those containing from 1 to about 24 
carbon atoms. Preferred cycloalkyl radicals represented by R.sup.9 
--R.sup.12 are those containing from 4 to about 24 carbon atoms. Preferred 
alkenyl radicals represented by R.sup.9 --R.sup.13 are those containing 
from 2 to about 24 carbon atoms. Preferred aryl radicals represented by 
R.sup.9 --R.sup.13 and R.sup.17 are those containing from 6 to 24 carbon 
atoms. Preferred alkaryl and aralkyl radicals represented by R.sup.9 
--R.sup.13 and R.sup.17 are those containing from 7 to about 24 carbon 
atoms. Preferred divalent saturated aliphatic hydrocarbon radicals 
represented by R.sup.14 and R.sup.16 are those containing from 1 to about 
12 carbon atoms. Preferred divalent aromatic hydrocarbon radicals 
represented by R.sup.14 and R.sup.16 are those containing from 6 to about 
24 carbon atoms. Preferred oxirane ring containing monovalent saturated 
aliphatic hydrocarbon radicals represented by R.sup.15 are those 
containing from 2 to about 24 carbon atoms, while preferred oxirane ring 
containing monovalent aliphatic-aromatic hydrocarbon radicals represented 
by R.sup.15 are those containing from 8 to about 24 carbon atoms. 
The derivatives of epoxy cyclohexane are represented by the general formula 
##STR4## 
wherein: 
(a) R.sup.18 through R.sup.27 are independently selected from hydrogen; 
alkyl radicals; substituted alkyl radicals; alkenyl radicals; aryl 
radicals; aralkyl radicals; alkaryl radicals; OR.sup.29 radicals wherein 
R.sup.29 is selected from hydrogen, alkyl radicals, substituted alkyl 
radicals, alkenyl radicals, aryl radicals, alkaryl radicals, and aralkyl 
radicals; --R.sup.30 OR.sup.29 radicals wherein R.sup.30 is selected from 
divalent saturated aliphatic hydrocarbon radicals and divalent aromatic 
hydrocarbon radicals; --COOR.sup.29 radicals; --OOCR.sup.29 radicals; 
--R.sup.30 COOR.sup.29 radicals; OR.sup.31 radicals wherein R.sup.31 is 
selected from oxirane ring containing saturated aliphatic hydrocarbon 
radicals and oxirane ring containing aliphatic-aromatic hydrocarbon 
radicals; --R.sup.30 OR.sup.31 radicals; --OOCR.sup.31 radicals; 
--COOR.sup.31 radicals; --R.sup.30 OOCR.sup.31 radicals; and --R.sup.30 
COOR.sup.31 radicals; with the proviso that 
(b) one of R.sup.18 through R.sup.27 is selected from the class of divalent 
saturated aliphatic hydrocarbon radicals; divalent aromatic hydrocarbon 
radicals; --OR.sup.32 -- radicals wherein R.sup.32 is selected from 
divalent saturated aliphatic hydrocarbon radicals and divalent aromatic 
hydrocarbon radicals; --R.sup.30 OR.sup.32 -- radicals; --OOCR.sup.32 -- 
radicals; --COOR.sup.32 -- radicals; --R.sup.30 OOCR.sup.32 -- radicals; 
and --R.sup.30 COOR.sup.32 -- radicals. 
Preferred derivatives of epoxycyclohexane represented by Formula V are 
those wherein: 
(a) R.sup.18 through R.sup.27 are independently selected from the class 
consisting of hydrogen; alkyl radicals; substituted alkyl radicals; aryl 
radicals; alkaryl radicals; aralkyl radicals; and OR.sup.28 radicals 
wherein R.sup.28 is selected from hydrogen, alkyl radicals, substituted 
alkyl radicals, aryl radicals, alkaryl radicals, and aralkyl radicals; 
with the proviso that 
(b) one of R.sup.18 through R.sup.27 is selected from the class consisting 
of divalent saturated aliphatic hydrocarbon radicals; divalent aromatic 
hydrocarbon radicals; --OR.sup.32 -- radicals; and --R.sup.30 OR.sup.32 -- 
radicals. 
While in Formula V R.sup.21 is shown as falling within the definition of 
(b) and being bonded to the silicon atom this is done merely for the sake 
of convenience, clarity and illustration, and it is to be understood that 
any one of R.sup.18 through R.sup.27 can fall within the definition of (b) 
and be bonded to the silicon atom. 
In Formula V preferred alkyl radicals represented by R.sup.18 through 
R.sup.27, R.sup.28 and R.sup.29 are those containing from 1 to about 24 
carbon atoms. Preferred substituted alkyl radicals represented by R.sup.18 
through R.sup.27, R.sup.28 and R.sup.29 are those containing from 1 to 
about 24 carbon atoms. Preferred alkenyl radicals represented by R.sup.18 
through R.sup.27 and R.sup.29 are those containing from 2 to about 24 
carbon atoms. Preferred aryl radicals represented by R.sup.18 through 
R.sup.27, R.sup.28 and R.sup.29 are those containing from 6 to about 24 
carbon atoms. Preferred aralkyl radicals represented by R.sup.18 through 
R.sup.27, R.sup.28 and R.sup.29 are those containing from 7 to about 24 
carbon atoms. Preferred alkaryl radicals represented by R.sup.18 through 
R.sup.27, R.sup.28 and R.sup.29 are those containing from 7 to about 24 
carbon atoms. Preferred divalent saturated aliphatic hydrocarbon radicals 
represented by R.sup.30 and R.sup.32 are those containing from 1 to about 
12 carbon atoms. Preferred divalent aromatic hydrocarbon radicals 
represented by R.sup.30 and R.sup.32 are those containing from 6 to about 
24 carbon atoms. Preferred oxirane ring containing saturated aliphatic 
hydrocarbon radicals represented by R.sup.31 are those containing from 2 
to about 24 carbon atoms. Preferred oxirane ring containing 
aliphatic-aromatic hydrocarbon radicals represented by R.sup.31 are those 
containing from 8 to about 24 carbon atoms. 
Some nonlimiting illustrative examples of substituted alkyl radicals are 
those containing one or more inorganic substituent groups such as hydroxyl 
and/or halides (chlorine, fluorine, bromine and iodine). 
Some nonlimiting illustrative examples of divalent organic radicals 
containing carbon and oxygen atoms in the ring structure which together 
with the silicon atom form a cyclic structure as represented by R.sup.3 in 
Formula III include --CH.sub.2 --O--CH.sub.2 --, --C.sub.2 H.sub.4 
--O--C.sub.2 H.sub.4 --O--C.sub.2 H.sub.4 --, --O--C.sub.3 H.sub.6, 
--O--C.sub.3 H.sub.6 --O--CH.sub.2 --, --CH.sub.2 --O--C.sub.4 H.sub.8 
--O--CH.sub.2 --, and the like. Preferably these compounds are the 
divalent saturated aliphatic organic radicals containing from 2 to about 
24 carbon atoms and from 1 to about 6 oxygen atoms. 
Some nonlimiting illustrative examples of divalent saturated aliphatic 
hydrocarbon radicals represented by R.sup.5, R.sup.14, R.sup.16, R.sup.30 
and R.sup.32 include --CH.sub.2 CH.sub.2 --, 
##STR5## 
--CH.sub.2 CH.sub.2 CH.sub.2 CH.sub.2 --, and the like. Some nonlimiting 
illustrative examples of divalent aromatic hydrocarbon radicals 
represented by R.sup.5, R.sup.14, R.sup.16, R.sup.30 and R.sup.32 include 
##STR6## 
Some nonlimiting illustrative examples of oxirane ring containing 
monovalent saturated aliphatic hydrocarbon radicals represented by 
R.sup.15 and R.sup.31 include 
##STR7## 
and the like. 
Some nonlimiting illustrative examples of oxirane ring containing 
aliphatic-aromatic radicals represented by R.sup.15 and R.sup.31 include: 
##STR8## 
When Z in Formula III represents a monovalent derivative of epoxy ethane as 
represented by Formula IV, Formula III becomes 
##STR9## 
When Z in Formula III represents a monovalent derivative of epoxy 
cyclohexane as represented by Formula V, Formula III becomes 
##STR10## 
While in Formula VI R.sup.10 is depicted as being bonded to the silicon 
atom it is to be understood that bonding to the silicon atom can occur 
through any one of R.sup.9 through R.sup.12. So also in Formula VII where 
R.sup.21 is depicted as being bonded to the silicon atoms it is to be 
understood that bonding can occur through any one of R.sup.18 through 
R.sup.27. 
The epoxy silanes of Formulae VI and VII are compounds well known to those 
skilled in the art and are generally commercially available, or can be 
prepared by known methods. 
Some nonlimiting illustrative examples of compounds represented by Formulae 
VI and VII, as well as epoxy siloxanes of Formula VIII, are set forth in 
Table I. 
The epoxy siloxane compounds useful as stabilizers in the 
polyester-carbonate compositions of the instant invention are represented 
by the general formula 
##STR11## 
wherein b is an integer having a value from 1 to about 10; R.sup.33 and 
R.sup.34 are independently selected from alkyl radicals of from 1 to about 
24 carbon atoms, alkenyl radicals of from 2 to about 24 carbon atoms, aryl 
radicals of from 6 to 24 carbon atoms, aralkyl radicals of from 7 to about 
24 carbon atoms, alkaryl radicals containing from 7 to about 24 carbon 
atoms, hydrogen, alkoxy radicals containing from 1 to about 24 carbon 
atoms, and aryloxy radicals containing from 6 to 24 carbon atoms; and each 
Z is independently selected from the monovalent epoxy radicals represented 
by Formulae IV and V. 
In Formula VIII both Zs can be the same or they may be different. Thus, for 
example, one Z may be an epoxy radical represented by Formula IV while the 
other Z may be an epoxy radical represented by Formula V; one Z may be one 
epoxy radical represented by Formula IV while the other Z is a different 
epoxy radical represented by Formula IV; or one Z may be an epoxy radical 
represented by Formula V while the other Z is a different epoxy radical 
represented by Formula V. 
TABLE I 
______________________________________ 
beta(3,4-epoxycyclohexyl)ethyl-trimethoxy silane; 
2,2,3,3,4,4-hexamethyl-5,6-epoxycyclohexylmethyl tri- 
vinyl silane; 
1-(beta-3,4-epoxycyclohexyl)ethyl-1-methyl-1-sila-2- 
oxa-cyclohexane; 
gamma(glycidoxypropyl)trimethoxy silane; 
gamma(glycidoxypropyl)ethoxy silane; 
p-glycidoxyphenyl-dicyclohexyl acetoxy silane; 
bis(3-glycidoxypropyl)tetramethyl disiloxane; 
1,8-di(beta-3,4-epoxycyclohexyl)ethyl-octadiphenyl- 
siloxane; and 
1,3-di(2,3-epoxypropane)hexaethoxy trisiloxane. 
______________________________________ 
The polyester-carbonate compositions of the instant invention may contain 
only one of the aforedescribed epoxy hydrolytic stabilizers or they may 
contain a mixture of two or more of these stabilizers. Thus, for example, 
the polyester-carbonate compositions of the instant invention may contain 
two different epoxy stabilizers of Formula VI; two different stabilizers 
of Formula VII; two different stabilizers of Formula VIII; one epoxy 
stabilizer of Formula VII and one epoxy stabilizer of Formula VI; one 
epoxy stabilizer of Formula VI and one epoxy stabilizer of Formula VIII; 
or one epoxy stabilizer of Formula VII and one epoxy stabilizer of Formula 
VIII. 
The amount of epoxy stabilizer present in the polyester-carbonate 
compositions of the instant invention is a hydrolytically stabilizing 
amount. By hydrolytically stabilizing amount is meant an amount of 
stabilizing compound effective to stabilize the polyester-carbonate resin 
against hydrolytic degradation. Generally this amount is from about 0.005 
to about 4.0 weight percent, based on the weight of the 
polyester-carbonate resin present in the composition. Preferably this 
amount ranges from about 0.01 to about 2 weight percent, and more 
preferably from about 0.02 to about 0.5 weight percent. 
The polyester-carbonate resin compositions of the present invention are 
formulated by adding the epoxy stabilizing compounds described above to 
the polyester-carbonate resin and mixing or blending the stabilizer and 
resin by generally mechanical means such as stirring, blending in a 
mechanical blender, and the like to form the compositions of the instant 
invention. 
The compositions of the instant invention may optionally contain other 
commonly known and used additives such as antistatic agents, antioxidants, 
ultraviolet radiation absorbers, mold release agents, colorants, fillers 
such as glass fibers, graphite fibers, etc, impact modifiers, color 
stabilizers, flame retardants, and the like. Some nonlimiting illustrative 
examples of suitable ultraviolet radiation absorbers include the 
benzophenones and the benzotriazoles. Some nonlimiting illustrative 
examples of suitable color stabilizers include the organophosphites. Some 
of these organophosphites are disclosed in U.S. Pat. Nos. 4,138,379; 
4,118,370 and 3,305,520, all of which are incorporated herein by 
reference. Some useful flame retardants are those disclosed in U.S. Pat. 
Nos. 3,915,926; 4,197,232 and the organic alkali metal salts and organic 
alkaline earth metal salts of sulfonic acid as described in U.S. Pat. Nos. 
3,933,734; 3,948,851; 3,926,968; 3,919,167; 3,909,490; 3,953,396: 
3,931,100; 3,978,024; 3,953,399; 3,917,559; 3,951,910 and 3,940,366, all 
of which are incorporated herein by reference. 
As mentioned previously the compositions of the instant invention may 
contain color stabilizers. The preferred color stabilizers are the 
organophosphites. These organophosphites and their color stabilizing 
properties are known to those skilled in the art, and are disclosed, for 
example, in U.S. Pat. Nos. 3,305,520; 4,138,379; 4,118,370 and 4,102,859, 
all of which are incorporated herein by reference. Generally, absent the 
color stabilizers the color of the aromatic polyester-carbonate molded 
articles tends to deteriorate when exposed to high temperatures such as 
those existant during processing or in applications associated with high 
temperature environments. Sometimes this color deterioration is so severe 
that these aromatic polyester-carbonate articles become commercially 
unacceptable. The addition of the organophosphite color stabilizers to the 
polyester-carbonate resins generally remedies this problem of color 
deterioration. However, these organophosphite color stabilizers generally 
tend to adversely affect the hydrolytic stability of the aromatic 
polyester-carbonate resin. Thus, in the case where organophosphite color 
stabilizers are present in the aromatic polyester-carbonate compositions 
it is even more essential to stabilize these compositions against 
hydrolytic degradation than in the case of aromatic polyester-carbonate 
compositions containing no organophosphite color stabilizers.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The following examples are set forth to further illustrate the present 
invention and are not to be construed as limiting the invention thereto. 
Unless otherwise specified, where parts or percents are mentioned, they 
are parts or percents by weight. 
EXAMPLE 1 
This example illustrates a control composition, falling outside the scope 
of the instant invention, which is comprised of a polyester-carbonate 
resin derived from bisphenol A, a mixture of terephthaloyl dichloride and 
isophthaloyl dichloride, and phosgene. 
The resin of this example is prepared by adding to a reactor vessel 16 
liters of methylene chloride, 8 liters of water, 1906 grams (8.36 moles) 
of bisphenol A, 24 milliliters of triethylamine, 3.4 grams of sodium 
gluconate, and 65 grams of para-tertiary-butylphenol chain terminator. At 
a pH of between about 9-10.5, 1089.6 grams (5.37 moles) of a mixture of 
15% by weight of isophthaloyl dischloride and 85% by weight of 
terephthaloyl dichloride in 2 liters of methylene chloride are added over 
a 10 minute interval while controlling the pH at about 9-10.5 with 35% 
aqueous caustic. After the addition of the diacid chloride mixture, 
phosgene is added at a rate of 36 grams per minute for 12 minutes while 
controlling the pH at about 10-11 with 35% aqueous caustic. The polymer 
mixture is diluted with 2 liters of methylene chloride and the brine phase 
is separated. The resulting polymer phase is washed once with 0.1 N HCl 
and three times with water and is then recovered by high steam 
precipitation to yield a white powder. This resin product is then fed to 
an extruder operating at a temperature of about 600.degree. F. to extrude 
the resin into strands and the extruded strands are chopped into pellets. 
The pellets are then injection molded at about 650.degree. F. into test 
samples measuring about 2".times.2".times.0.1". 
EXAMPLE 2 
This example illustrates a hydrolytically stabilized polyester-carbonate 
composition falling within the scope of the present invention. 
To the powdered polyester-carbonate resin prepared substantially in 
accordance with the procedure of Example 1 is added 
gamma-glycidoxypropyl-trimethoxysilane in an amount of 0.1 parts by weight 
per hundred parts by weight or resin. The resin and the stabilizer are 
thoroughly mixed and the mixture is then fed into an extruder operating at 
a temperature of about 600.degree. F. to extrude the composition into 
strands and the extruded strands are chopped into pellets. The pellets are 
then injection molded at about 650.degree. F. into test samples measuring 
about 3".times.2".times.0.1". 
EXAMPLE 3 
This example illustrates a stabilized polyester-carbonate composition 
falling within the scope of the instant invention. 
To the powdered polyester-carbonate resin prepared substantially in 
accordance with the procedure of Example 1 is added 
beta(3,4-epoxycyclohexyl)ethyl-trimethoxy-silane in an amount of 0.1 parts 
by weight per hundred parts by weight of resin. The resin and the 
stabilizer are thoroughly mixed and the mixture is then fed to an extruder 
operating at a temperature of about 600.degree. F. to extrude the 
composition into strands, and the strands are chopped into pellets. The 
pellets are then injection molded at about 650.degree. F. into test 
samples measuring about 3".times.2".times.0.1". 
EXAMPLE 4 
This example illustrates yet another hydrolytically stabilized 
polyester-carbonate composition of the present invention. 
To the powdered polyester-carbonate resin prepared substantially in 
accordance with the procedure of Example 1 is added 0.1 parts by weight 
per hundred parts by weight of resin of bis(3-glycidoxypropyl) 
tetramethyldisiloxane stabilizer. The resin and the stabilizer are 
thoroughly mixed and the mixture is fed into an extruder operating at a 
temperature of about 600.degree. F. to extrude the mixture into strands, 
and the extruded strands are chopped into pellets. The pellets are then 
injection molded at about 650.degree. F. into test samples measuring about 
3".times.2".times.0.1". 
EXAMPLE 5 
This example illustrates a color stabilized but hydrolytically unstabilized 
polyester-carbonate composition falling outside the scope of the instant 
invention. 
To the powdered polyester-carbonate resin prepared substantially in 
accordance with the procedure of Example 1 is added 0.03 parts by weight 
per hundred parts by weight of resin 
bis(2,4-ditertiarybutylphenyl)pentaerythritol diphosphite color 
stabilizer. The resin and the color stabilizer are thoroughly mixed and 
the mixture is fed to an extruder operating at a temperature of about 
600.degree. F. to extrude the mixture into strands, and the extruded 
strands are chopped into pellets. The pellets are then injection molded at 
about 650.degree. F. into test samples measuring about 
3".times.2".times.0.1". 
EXAMPLE 6 
This example illustrates a color stabilized and hydrolytically stabilized 
polyester-carbonate composition falling within the scope of the present 
invention. 
To the powdered polyester-carbonate resin prepared substantially in 
accordance with the procedure of Example 1 are added 0.1 parts by weight 
per hundred parts by weight of resin of gamma-glycidoxypropyltrimethoxy 
silane hydrolytic stabilizer and 0.03 parts by weight per hundred parts by 
weight of resin of bis(2,4-ditertiarybutylphenyl)pentaerythritol 
diphosphite color stabilizer. The resin and the stabilizers are thoroughly 
mixed and the mixture is fed to an extruder operating at a temperature of 
about 600.degree. F. to extrude the composition into strands and the 
extruded strands are chopped into pellets. The pellets are then injection 
molded at about 650.degree. F. into test samples measuring about 
3".times.2".times.0.1". 
EXAMPLE 7 
This example illustrates another color stabilized and hydrolytically 
stabilized aromatic polyester-carbonate composition of the instant 
invention. 
To the powdered polyester-carbonate resin prepared substantially in 
accordance with the procedure of Example 1 are added 0.1 parts by weight 
per hundred parts by weight of resin of 
beta(3,4-epoxycyclohexyl)ethyltrimethoxy silane hydrolytic stabilizer and 
0.03 parts by weight per hundred parts of resin of 
bis(2,4-ditertiarybutylphenyl)pentaerythritol diphosphite color 
stabilizer. The resin and the stabilizers are thoroughly mixed and the 
mixture is fed to an extruder operating at a temperature of about 
600.degree. F. to extrude the mixture into strands, and the extruded 
strands are chopped into pellets. The pellets are injection molded at 
about 650.degree. F. into test samples measuring about 
3".times.2".times.0.1". 
EXAMPLE 8 
This example illustrates yet another color stabilized and hydrolytically 
stabilized aromatic polyester-carbonate composition of the instant 
invention. 
To the powdered polyester-carbonate resin prepared substantially in 
accordance with the procedure of Example 1 there are added 0.1 parts by 
weight per hundred parts by weight of resin of 
bis(3-glycidoxypropyl)tetramethyldisiloxane hydrolytic stabilizer and 0.03 
parts by weight per hundred parts by weight of resin of 
bis(2,4-ditertiarybutylphenyl)pentaerythritol color stabilizer. The resin 
and the stabilizers are thoroughly mixed and the mixture is fed to an 
extruder operating at a temperature of about 600.degree. F. to extrude the 
mixture into strands, and the extruded strands are chopped into pellets. 
The pellets are then injection molded at about 650.degree. F. into test 
samples measuring about 3".times.2".times.0.1". 
Each of the samples of Examples 1-8 is subjected to ASTM Yellownes Index 
(YI) Test D 1925. Each of the samples of Examples 1-8 is also subjected to 
ASTM test method D 1003 for determining light transmission on the samples 
before and after steam autoclaving at 250.degree. F. The higher the 
percent of light transmitted the better the clarity of the sample, and 
thus the lower the degree of hydrolytic degradation of the sample. 
Conversely, the lower the percent of light transmitted the lesser the 
clarity of the sample, and thus the greater the degree of hydrolytic 
degradation of the sample. The results of these tests are set forth in 
Table II. 
Each of the samples of Examples 1-8 is measured for molecular weight 
degradation, caused by hydrolysis, by measuring the intrinsic viscosity 
before and after steam autoclaving at 250.degree. F. The greater the 
change in the intrinsic viscosity the greater the degradation of the 
polyester-carbonate by hydrolysis. The results of this test is set forth 
in Table III. 
TABLE II 
______________________________________ 
% Light Transmitted 
After Autoclaving 
EXAM- % Light Transmitted 
(Time in Hours) 
PLE No. YI Before Autoclaving 
72 144 
______________________________________ 
1 27.1 83 62 44 
2 20.5 85 79 69 
3 25.3 85 80 76 
4 23.5 84 79 75 
5 17.7 87 74 4 
6 16.8 86 82 76 
7 14.1 87 82 78 
8 15.5 86 81 75 
______________________________________ 
TABLE III 
______________________________________ 
Intrinsic Viscosity 
After Autoclaving 
Intrinsic viscosity 
(Time in Hours) 
EXAMPLE NO. Before Autoclaving 
72 144 
______________________________________ 
1 0.507 0.427 0.343 
2 0.514 0.471 0.421 
3 0.506 0.472 0.432 
4 0.517 0.497 0.475 
5 0.515 0.362 0.204 
6 0.519 0.484 0.427 
7 0.518 0.486 0.454 
8 0.520 0.473 0.387 
______________________________________ 
The data in tables II and III clearly demonstrate the effect autoclaving 
has on the aromatic polyester-carbonate tests samples with and without the 
particular epoxy hydrolytic stabilizer additives of the instant invention. 
It is clear from this data that the test samples molded from 
polyester-carbonate compositions containing the epoxy hydrolytic 
stabilizers of the instant invention, i.e., Examples 2-4 and 6-8, are 
hydrolytically more stable than test samples molded from 
polyester-carbonate resin containing no hydrolytic stabilizers, i.e. 
Examples 1 and 5. This difference in hydrolytic stability is particularly 
striking when organophosphite color stabilizers are used with the aromatic 
polyester-carbonate resin, i.e., Examples 5-8. 
It will thus be seen that the objects set forth above among those made 
apparent from the preceding description are efficiently attained, and 
since certain changes may be made in the processes and compositions 
described above without departing from the scope of the invention, it is 
intended that all matters contained in the above description shall be 
interpreted as illustrative rather than limiting.