Note: Descriptions are shown in the official language in which they were submitted.
RD-17,912
1338116
PREPARATION OF SPIROBIINDANE POLYARYLATES,
AND SPIROBIINDANE POLYARYLATE-POLY~LnY~ENE TER~ ~ALATE
COPOLYMERS, VIA MELT POLYMERIZATION
This invention relates to aromatic polyesters,
sometimes referred to as polyarylates, and more particularly
to such polyesters which contain a spirobiindane moiety in
the main polymer chain and to methods for making homopoly-
mers and copolymers of spirobiindane-containing aromatic
polyesters.
The polyarylates of this invention are aromatic
polyesters derived from a spirobiindane dihydric phenol and,
optionally, a non-spirodihydric phenol, such as 2,2-bis(4-
hydroxyphenyl)propane-6,6'-diol and aromatic dicarboxylic
acids such as terephthalic and isophthalic acid. These
polyarylates have many superior properties which make them
useful as engineering thermoplastics, including good mechan-
ical properties, high glass transition temperature, good
fire retardancy, and good solvent resistance. They also
have good processibility which allows them to be molded into
articles.
This invention relates to polyarylates which
contain a spirobiindane moiety in the main polymer chain.
The only previously known spirobiindane polyarylate
preparation method is through the use of spirobiindane
bisphenol and isophthaloyl chloride. K.C. Stueben, "Journal
of Polymer Science: Part A", 3 (1965) pp.3209-3217, reported
the preparation of a spiro~iindane isophthalate ~y an
interfacial polymerization reaction. Independent
preparation of the disclosed polyarylate material, however,
produced a product having a molecular weight and a glass
--1--
`~
RD-17,912
1338116
transition temperature much lower than that reported by
Steuben.
In the Stueben process for producing spirobiin~ne
polyarylates, a problem exists which must be solved in order
to have a homogeneous polyarylate compound prepared. When
spirobiindane compounds are condensed with ring-inducing
diacids, i.e. diacids having nonlinear configuration such as
isophthalic acid, to form polyarylates, a low molecular
weight fraction is generated which may add a deleterious
plasticizing property to the high polymeric compound
prepared. These low molecular weight materials are believed
to be a series of cyclic spirobiindane polyarylates of the
formula:
0 ~ Me
(I)
~ Me Me ~ '~o
wherein S is 1,2,3,4,5.
It is theorized that the formation of these cyclic
polyarylates occur either via a chain scission and
subsequent cyclization of the long-chain polyarylate after
it has been formed or directly from the short chain
oligomers. This transformation is believed to be
equilibrium controlled with the e~uilibrium shifting in
favor of the creation of the long-chain polymer at elevated
RD-17,912
133811!i
temperatures and concentrations experienced in the melt
process.
The use of spirobiindane polyarylates for
polymeric melt blends may be restricted because of the high
glass transition temperature associated with these
polyarylates. It may be impossible to use polyarylates
which contain spirobiindane moieties in certain melt blends
because temperature requirements for polyarylate melt
blending may prohibit the use of polymeric resins having
much lower glass transition temperatures.
An object of the present invention, therefore, is
to prepare a spirobiindane polyarylate with minimal cyclic
oligomer formation, through the use of a linear diacid.
A further object is to prepare SBI polyarylates
with minimal cyclic oligomer formation through the addition
of linear monomers, such as bisphenol A in combination with
terephthalic acid to SBI-isophthalic acid homopolymers.
A further object is to prepare a spirobiindane
copolyarylate with a preselected specific glass transition
temperature between the glass transition temperatures of the
corresponding homopolyarylates by varying the percent
composition of each of the monomers in the polymerization
reaction.
A further object is to prepare spirobiindane
polyarylate-polyester copolymers having higher molecular
weight and lower glass transition temperatures than the
original spirobiindane polyarylate.
A further object is to prepare a spirobiindane
polyarylate-polyester copolymer possessing a glass transi-
3~ tio~ temperature significantly higher than any previouslyformed polyarylate-polyester copolymer.
These and other objects are achieved by the
practice of this invention and will appear hereinafter.
-3-
RD-17,912
133811~i
The homopolyarylates and copolyarylates described
herein can be prepared by melt polymerizing in the presence
of a diphenyl ether or a substituted derivative thereof and,
optionally, a magnesium catalyst,
S (A) at least one spirodihydric phenol or specified
derivative thereof having the formula
(R)n Me ,Me
\/
RlO 1 oRl ~ (II)
Me Me (R)n
wherein R is a monovaLent hydrocarbon radical
selected from the group consisting of alkyl
radicals, cycloalkyl radicaIs, aryl radicals,
aralkyl radicals, alkaryl radicals, or halogen
radicals, n is selected from positive integers
having a value from 0 to 3 inclusive, and Rl is
hydrogen or acetyl radical;
(B) at least one aromatic dicarboxylic acid or
specified derivative thereof having the formula:
~ C R2 C ~ (III)
wherein R2 is an aryl or substituted aryl radi-
cals, and R3 is a hydroxide or chloride radicals,
(C) optionally, a dihydric phenol of the formula,
1~3$11~ RD-17,912
Ho-A2_y-A3-oH (IV)
wherein each of A2 and A3 is a monocyclic divalent
aromatic radical, preferably p-phenylene and y is
a bridging radical in which 1 of 2 atoms separate
A2 from A3, and the spirobiindane moiety comprises
about 5-}00% of total dihydroxyaromatic compounds
in the mixture.
The resulting polyarylate can be recovered or further melt
copolymerized with polyesters of the formula
- ol o
-O-M-O-C ~ ~- , (V)
wherein M represents a chain of about 2 to about 4 methylene
groups, to provide copolymers represented by formula:
(R)n /Me
lS ~ C ~ ~C O-M-O-Il ~ C - ,(VI)
Me Me (R)n x _ Y
wherein X and Y represent the number of monomer units in the
polymer chain or a segment of the chain.
The spiro dihydric phenols or substituted deri~a-
tive thereof within the scope of this invention are those
represented by the general formula:
-5-
RD-17,912
133811~
n
CH3
H0 ~ C / CH3
~ \ / H
C~ , (VII)
\/ `H
' ~ ~ ~H
CH3
(R)n
wherein R is independently selected from monovalent hydro-
carbon radicals and halogen radicals; n is independently
selected from positive integers having a value of from 0 to
3 inclusive, and Rl is hydrogen or acetyl radical. The
monovalent hydrocarbon radicals represented by R include the
alkyl radicals, the cycloalkyl radicals, the aryl radicals,
the aralkyl radicals, and the alkaryl radicals.
The alkyl radicals represented by R are preferably
those containing from 1 to about 12 carbon atoms. These
include the branched alkyl radicals and the straight chain
alkyl radicals. Illustrative examples of suitable alkyl
radicals include methyl, ethyl, propyl, isopropyl, butyl,
tertiary-butyl, pentyl, neopentyl, and hexyl.
The cycloalkyl radicals represe~ted by R are
preferably those containing from 4 to about 7 ring carbon
atoms. These include cyclobutyl, cyclopentyl, cyclohexyl,
methylcyclohexyl, and cycloheptyl.
RD-17,912
13~811~
The aryl radicals represented by R are preferably
those containing from 6 to 12 ring carbon atoms. These
include phenyl, biphenyl, and naphthyl.
Preferred aralkyl and alkaryl radicals represented
by R are those containing from 7 to about 14 carbon atoms.
These include, but are not limited to benzyl, ethylphenyl,
phenylbutyl, phenylpropyl, propylphenyl, and phenylethyl.
The preferred halogen radicals represented by R
are chlorine and bromine.
Preferably R is independently selected from
chlorine, bromine, and lower alkyl radicals containing from
1 to about 5 carbon atoms.
In the dihydric phenol compound of Formula VII
when more than one R substituent is present they may be the
same or different. The positions of the hydroxyl groups and
R on the aromatic nuclear residues may be varied in the
ortho, meta or para positions.
The spiro dihydric phenols of Formula VII are
compounds that are known in the art and are commercially
available or may be readily prepared by known methods.
These methods of preparation of the spiro dihydric phenols
of Formula VII include those described by R.F. Curtis and
KØ Lewis in "Journal of the Chemical Society" (England),
1962, p. 420; and R.F. Curtis in "Journal of the Chemical
Society" (England), 1962, p. 417.
These spiro dihydric phenols may be conveniently
prepared by (i) reacting two moles of a phenol with one
mole of acetone, and (ii) thereafter co-reacting 3 moles of
the product of (i) under acidic conditions to form the spiro
dihydric phenols of Formula VII and 4 moles of a phenol.
The acids which may be utilized in (ii) can include such
acids as anhydrous methane sulfonic acid, anhydrous hydro-
chloric acid, and the like.
RD-17,912
~3381l~
Illustrative examples of the spiro dihydric
phenols within the scope of Formula (VII) include
5,5',7,7'-tetrachloro-6,6'-dihydroxy-3,3,3',3'-tetra-
methyl-bis-l,l'-spiroindane(+);
3,3,5,7,3',3',5',7'-octamethyl-6,6'-dihydroxy-bis-1,1'-
spiroindane(+);
5,7,5',7'-tetraethyl-6,6'-dihydroxy-bis-1,1'-
spiroindane(+);
3,3,5,3',3',5'-hexamethyl-6,6'-dihydroxy-bis-1,1'-
spiroindane(+);
7,7'-dichloro-6,6'-dihydroxy-3,3,5,3',3',5'-hexamethyl-
bis-l,l'-spiroindane(+); and
5',7-diethyl-6,6'-dihydroxy-3,3,3',3',5',7'-hexamethyl-
bis-1,1'-spiroindane(+).
The polyarylates and polyarylate-polyester copoly-
mers which may be prepared by the method of this invention
are those containing units derived from a spiro dihydric
phenol or alkyl- or halo-substituted analogs thereof. The
preferred spirobiindane bisphenol is SBI.
For the polyarylates and polyarylate-polyester
copolymers, there may additionally be employed a second
dihydroxyaromatic compound of the formula,
Ho_A1_oH , (VIII)
wherein Al is a divalent aromatic radical. Such radicals
include aromatic hydrocarbon and substituted aromatic
hydrocarbon radicals, with illustrative substituents being
alkyl, cycloalkyl, alkenyl (e.g., crosslinkable-graftable
moieties such as allyl), halo (especially fluoro, chloro
and/or bromo), nitro and alkoxy.
1 33~ RD-17,912
The preferred A1 values have the formula,
-A2-Y-A3- , (IX)
wherein each of A2 and A3 is a monocyclic divalent aromatic
radical and Y is a bridging radical in which one or two
atoms separate A2 from A3. The free valence bonds in
Formula IX are usually in the meta or para positions of A2
and A3 in relation to Y.
In Formula IX, the A2 and A3 values may be unsub-
stituted phenylene or substituted derivatives thereof
wherein the substituents are as defined for Al. Unsub-
stituted phenylene radicals are preferred. Both A2 and A3
are preferably p-phenylene, although both may be o- or
m-phenylene or one o- or m-phenylene and the other p-phen-
ylene.
The bridging radical, Y, is one in which one or
two atoms, preferably one, separate A2 from A3. It is most
often a hydrocarbon radical and particularly a saturated
C1 12 aliphatic or alicyclic radical such as methylene,
cyclohexylmethylene, [2.2.1]bicycloheptylmethylene, ethy-
lene, ethylidene, 2,2-propylidene, 1,1-(2,2-dimethyl-
propylidene), cyclohexylidene, cyclopentadecylidene, cy-
clododecylidene, or 2,2-adamantylidene, especially an
alkylidene radical. Aryl-substituted radicals are included,
as are unsaturated radicals and radicals containing atoms
other than carbon and hydrogen; e.g., oxy groups. Substi-
tuents such as those previously described with respect to
may be present on the aliphatic, alicyclic and aromatic
pe~i~ns of the Y group.
For the most part, the suitable compounds include
biphenols and especially bisphenols. Frequent reference
will be made to bisphenols hereinafter, but it should be
RD-17,912
1338116
understood that other compounds equivalent thereto may be
employed as appropriate. Bisphenol A (in which Y is iso-
propylidene and A2 and A3 are each p-phenylene) is preferred
for reasons of availability and particular suitability for
the purposes of the invention.
The carboxylic acids which may be used include the
aromatic dicarboxylic acids. The difunctional carboxylic
acids which may be used generally will conform to the
formula,
HOOC-(R2)-COOH, (X)
wherein R2 is an aromatic group such as phenylene, bipheny-
lene, substituted phenylene, substituted biphenylene,
naphthylene, and substituted naphthylene, two or more
aromatic groups connected through non-aromatic linkages such
as alkylidene groups; and a divalent aralkyl radical such as
tolylene, xylylene, and the like.
Preferred difunctional carboxylic acids are the
aromatic dicarboxylic acids, i.e., those acids of Formula X
wherein R2 represents a divalent aromatic radical. The
preferred aromatic dicarboxylic acids are those represented
by the general formula,
1l 1
HOC ~ OH , (XI)
(R4)j
wherein R is independently selected from monovalent hydro-
carbon radicals and halogen radicals, and j is a positive
integer having a value of from 0 to 4 inclusive.
--10--
RD-17,912
1 ~3811~
The monovalent hydrocarbon radicals represented by
R4 include the alkyl radicals, the cycloalkyl radicals, the
aryl radicals, the aralkyl radicals, and the alkaryl radi-
cals. The carbon atom limitations for each group are the
same as for the aforementioned R group of Formula VII.
The preferred halogen radicals are the chlorine
and bromine radicals. Alkyl of one to five carbon atoms is
also preferred.
Particularly useful aromatic dicarboxylic acids of
Formula XI are those wherein j is 0 to 3, and R4 is an alkyl
radical, preferably one containing from 1 to about 5 carbon
atoms.
When more than one R4 substituent is present on
the ring carbon atoms of the aromatic carbocyclic residue
they may be the same or different.
Mixtures of these carboxylic acids may be employed
in lieu of individual carboxylic acid to form copolyary-
lates. Therefore, wherever the term difunctional carboxylic
acid is employed herein it is meant to include mixtures of
two or more different difunctional carboxylic acids as well
as individual difunctional carboxylic acids.
Particularly useful aromatic dicarboxylic acids
are isophthalic acid, terephthalic acid, and mixtures
thereof.
Rather than utilizing the difunctional aromatic
carboxylic acids per se it is possible, and sometimes even
preferred, to employ ester forming reactive derivatives such
as the acid dichlorides. Thus, for example, instead of
using isophthalic acid, terephthalic acid, or mixtures
30 thereof it is possible to use isophthaloyl dichloride,
terephthaloyl dichloride, or mixtures thereof.
The polyesters which are suitable for use in
synthesizing the polyester-polyarylate copolymer are derived
RD-17,912
1~3811~
from an aliphatic diol containing from 2 to 4 carbon atoms
and at least one aromatic dicarboxylic acid. The polyesters
have repeating structural units of the following general
formula:
O O
O-M-O-C ~ C - , (XII)
wherein M is an integer of from 2-4. The preferred polyes-
ters are poly(ethylene terephthalate) and poly(butylene
terephthalate), and most preferred is poly(ethylene tere-
phthalate).
The magnesium catalyst which may be used in the
polyarylate formation reaction is selected from magnesium,
magnesium oxide, and magnesium salt of an inorganic acid, or
organic acid or mixtures thereof, as disclosed by Maresca et
al., U.S. Patent No. 4,296,232 and Berger et al., U.S.
Patent No. 4,294,956, The salts of the organic
acid include acetates, propionates, benzoates, oxalates,
acetyl-acetonates, or mixtures thereof. The preferred
catalyst is magnesium acetate. The catalyst is present in
the reaction in a catalytically effective amount which can
be, for example, from about 1 to about 1000, preferably from
about 10 to about 50 parts per million, based on the weight
of the polyarylate produced.
The reaction of the diester derivative of a spiro
dihydric phenol and, optionally, a diyhydric phenol with an
aromatic dicarboxylic acid or acids or derivatives thereof
are carried out in the presence of from about 10 to about
60, preferably from about 25 to about 40, and most prefer-
ably, from about 30 to about 40 weight percent, based on the
-12-
RD-17,912
1 33~
weight of the polyarylate produced, of a diphenyl ether
compound. The diphenyl ether compound may be substituted.
These substituents are selected from alkyl groups, chlorine,
bromine, or any substituent which does not interfere with
5 the polyarylate-forming reaction.
The utilization of from about 10 to about 60
percent of a diphenyl ether compound in the diacetate
process prevents sublimation of the aromatic dicarboxylic
acid; thus producing polyarylates of acceptable molecular
10 weight. Also, the diphenyl ether compound provides for
better removal of the acetic acid by-product. Further, an
additional benefit in using a diphenyl ether compound in the
amounts indicated is that the viscosity of the system is
decreased. This decrease in viscosity provides a faster
15 reaction time since better mixing of the reactants occurs
which allows the reaction to proceed more quickly.
The process of this polyarylate formation is
carried out at a temperature of from about 260 to about
350C and preferably, from about 290 to about 320C. The
20 present process is generally conducted in an inert atmos-
phere (argon or nitrogen) to prevent deleterious side
reactions.
The polyarylate melt polymerization formation
reaction may be carried out batchwise or continuously, and
25 by using any apparatus desired. Melt polymerization as used
herein is defined as the reaction between at least two
monomers at high concentration and high temperature.
Moreover, the reac.ants may be added in any way or order
desired as long as the polymerization takes place in the
3~ presence of from about 10 to about 60 weight percent of
diphenyl ether compounds.
The reaction time is generally in the range of
from about 4 hours to about 8 hours, depending on the
RD-17,912
l338l~6
particular polyarylate being prepared. The polymerization
reaction is conducted for a period of time sufficient to
form the polyarylate as denoted by discontinuation of the
evolution of by-product.
The polyarylate may be prepared in the presence of
other materials such as molecular weight regulators, anti-
oxidants, thermal stabilizers, and the like. The polyary-
lates obtained may also be prepared in the presence of
well-known additives such as plasticizers, pigments, lubri-
cating agents, mold release agents, stabilizers, inorganic
fillers, and the like.
The process for preparing the spirobiindane
polyarylate-polyester copolymer requires a reaction tem-
perature of from about 260C to about 350C and preferably,
from about 290C to about 320C. The process is generally
conducted at reduced pressure of from about 0.5 mm Hg to
about lO0 mm Hg to provide a means for removing undesirable
by-products formed in the resulting copolymer.
The spirobiindane polyarylate-polyester copolymer
formation reaction may be carried out batchwise or continu-
ously, and by using any apparatus desired. Moreover, the
reactants may be added in any amount, method, or order
desired as long as the spirobiindane polyarylate-polyester
copolymer has only one Tg, is of higher molecular weight
than the original spirobiindane polyarylate used to generate
the copolymer, and maintains physical properties inherent to
both the starting polyarylate and polyester. The preferred
reaction of spirobiindane polyarylate with polyester occurs
when the ratio by weight is 3:1.
The reaction time is generally in the range of
from about 30 minutes to 3 hours, depending on the partic-
ular copolymer being prepared. The solid copolymer is
-14-
RD-17,912
1~3~116
formed by allowing the reaction mixture to cool to room
temperature.
The invention is further illustrated but not
limited by the following examples:
EXAMPLE 1
To a 3-neck round bottom flask, equipped with a
mechanical stirrer and a fractional distillation column was
added 30.00 g (0.0768 mol) of spirobiindane diacetate, 13.00
g (0.0780 mol) of isophthalic acid, 10 mg of magnesium
acetate trihydrate and 20 ml of diphenyl ether. The flask
was immersed into a 290C salt bath. After 30 min, acetic
acid distilled from the pot indicating polymerization had
occurred. The reaction vessel was heated at 290C for 4.5
hrs, raised to 300C for one hour and then 310C for one hr.
The diphenyl ether was removed by vacuum distillation (20 mm
Hg for 2 hr.). The polymerization was completed at 330C
and 1.O mm Hg for 5 hrs. The polymer isolated was an
amorphous yellow solid having 13C NMR analysis consistent
with a spirobiindane isophthalic acid polyarylate. The Tg
of the resultant polyarylate is about 245C.
EXAMPLES 2-5
The procedure of Example 1 was substantially
repeated except that the 13.00 g of isophthalic acid are
replaced with an isophthalic-terephthalic acid mixture.
Reactive amounts of each component by grams and mole ratio
are specified in Table I. The Tg of the resultant ~opoly-
arylate is determined and the results are also set forth in
Table I:
RD-17,912
1~38116
TABLE I
Grams Iso- Grams Tere- Mole ml
Example phthalic phthalic Ratio Diphenyl Tg
No. Acid Acid IPA/TPA Ether (C)
2 9.63 3.21 75:25 17.0 259
3 6.42 6.42 50:50 17.0 267
4 3.21 9.63 25:75 17.0 278
0.64 12.20 5:95 17.0 291
The first series of copolyarylates were prepared
by adding terephthalic acid to the original reaction mixture
of Example 1. The Tg of the resulting polyarylates vary
from about 245C for the homopolymer with isophthalic acid
as the diacid component, to 291C for the copolymer prepared
from a mixture of 95:5% terephthalic acid to isophthalic
acid. The Tg of the intermediate compositions increased
linearly with the addition of terephthalic acid.
EXAMPLES 6-8
The procedure of Example 1 is substantially
repeated except that the spirobii n~A~e diacetate is replaced
with a spirobiindane diacetate-bisphenol A diacetate
mixture. Reactive amounts by grams and mole ratio are
specified in Table II.
The Tg of the resultant polyarylate is determined
and the results are also set forth in Table II:
-16-
RD-17,912
133~116
TABLE II
Grams Grams Grams
Spiro- Bis- Mole Iso- ml
Ex. biindane phenol A Ratio phthalic Diphenyl Tg
No. Diacetate Diacetate SBI/BPA Acid Ether (C)
6 20.00 3.81 80:20 11.48 14.1 231
7 15.00 8.58 70:30 12.92 14.6 215
8 10.00 17.15 30:70 17.10 17.7 195
The second series of copolymers generated were
derived from the addition of bisphenol A diacetate to the
original reaction mixture of Example 1. The Tg of the
resulting polyarylates vary from 24SC for the original
homopolymer of Example 1 to 181C for a homopolymer
consisting of bisphenol A and isophthalic acid, commercially
available as Arylon, from duPont. The glass transition
temperatures of the intermediate compositions in this series
decreased linearly with the addition of bisphenol A.
EXAMPLES 9-11
The procedure of Example 1 is substantially
repeated except that in addition to 6.42 g of isophthalic
acid, 6.42 g of terephthalic acid is added. Further, the
34.2 g of spirobiindane diacetate are replaced with a
spirobiindane diacetate-bisphenol A diacetate mixture,
reaction amounts by grams and mole ratio are specified in
Table III.
The Tg of the resultant polyarylate is determined
and the results are set forth in Table III:
RD-17,~12
133811~
TABLE III
Grams Mole
Spiro- Grams Mole ml
Example biindane Bisphenol A Ratio Diphenyl Tg
No.Diacetate Diacetate S8I/BPA Ether (C)
922.50 4.27 75:25 17.0 251
1015.00 8.53 65:35 17.0 238
117.50 12.80 25:75 17.0 225
The final series of polyarylate compositions
prepared were comprised of combinations of spirobiindane and
bisphenol A with a 1:1 mixture of isophthalic acid and
terephthalic acid. The Tg of the resulting polyarylates
~ vary from 191C for the bisphenol A homopolymer commercially
available as Ardel, from Union Carbide, to 267C for the
spirobiindane containing copolymer of Example 3. These
compositions also had a linear increase in Tg with the
addition of the spirobiindane.
EXAMPLE 12
To a test tube reactor equipped with a helical
glass mechanical stirring shaft was added 3.0 g (Mw =
46,000) of spirobiindane-isophthalate polyarylate and l.Og
(I.V. 0.80) of polyethylene terephthalate. The mixture was
heated to 320C at reduced pressure of 1 mm Hg. After one
hour the heat was removed and the reaction mixture was
allowed to cool to room temperature. The polymer isolated
was an amorphous yellow solid having a 13C NMR analysis
consistent with a spirobiindane
isophthalate-polyethylene terephthalate copolymer. The
copolymer synthesized had Mw = ~9,000 and Mn = 18,800.
As illustrated by the data in Tables I, II or III,
three novel series of spirobiindane bisphenol containing
-18-
RD-17,912
13~ 11fi
polyarylates have been synthesized and identified. The
polyarylates differ in composition by either the ratio of
spirobiindane to bisphenol A or isophthalic to terephthalic
acids. The glass transition temperatures of these spirobi-
indane-containing polyarylates range from 182C to 291C.
Thus, it is possible to prepare a polyarylate with any
desired glass transition temperature between the SBI and
bisphenol-A homopolymer extremes by simply varying the
percent composition of each of the dihydric and diacid
monomers in the polymer formation reaction.
The data of Example 12 also shows that the copoly-
mers of spirobiindane polyarylate and polyethylene tereph-
thalate prepared by melt transesterification exhibit signif-
icantly higher glass transition temperatures and molecular
weights than the conventional prior art
polyarylate-polyester copolymer. Further, the spirobiindane
polyarylate-polyester copolymer possesses a lower glass
transition temperature than the spirobiindane polyarylate
used originally to generate the copolymer.
--19--
