Process for making polyetheresters with high aromatic ester content

A two-step process for making polyetherester resins is disclosed. A low molecular weight polyol reacts with an aromatic dicarboxylic acid in step one to produce a polyester intermediate. In step two, the polyester intermediate reacts with an anhydride or an aliphatic dicarboxylic acid in the presence of an insertion catalyst to produce a polyetherester resin that contains greater than about 10 wt. % of recurring units derived from the aromatic dicarboxylic acid. The polyetheresters are useful for making thermoset resins with excellent mechanical properties and chemical resistance.

FIELD OF THE INVENTION 
The invention relates to a process for making polyetheresters. In 
particular, the invention is a process for making polyetheresters that 
have a high content of aromatic ester recurring units. 
BACKGROUND OF THE INVENTION 
Recently, we described a new process for making polyetherester resins from 
polyethers (see U.S. Pat. No. 5,319,006). The process reacts a polyether 
with a cyclic anhydride (such as maleic anhydride) in the presence of a 
Lewis acid catalyst. The anhydride inserts randomly into carbon-oxygen 
bonds of the polyether to generate ester bonds in the resulting 
polyetherester resin. The polyetherester resin is then combined with a 
vinyl monomer, preferably styrene, and is cured to produce a 
polyetherester thermoset. 
We later found that, in addition to Lewis acids, protic acids that have a 
pKa less than about 0 and metal salts thereof will catalyze the insertion 
of an anhydride into the polyether to produce a polyetherester (see 
copending application Ser. No. 08/220,149, filed Mar. 30, 1994). We also 
discovered that these strong protic acids and their metal salts will 
catalyze the insertion of a carboxylic acid into a polyether (see 
copending application Ser. No. 08/228,845, filed Apr. 18, 1994). 
The ability to prepare polyetheresters by random insertion of anhydrides 
and carboxylic acids into polyethers provides a valuable way of making 
many unique polyetherester intermediates. These polyetheresters often have 
favorable performance characteristics compared with polyesters made by 
conventional esterification processes. Unfortunately, the insertion 
process does not work particularly well with high-melting aromatic 
dicarboxylic acids (such as isophthalic and terephthalic acids). Aromatic 
dicarboxylic acids are commonly incorporated into conventional unsaturated 
polyester resins to impart good mechanical properties and chemical 
resistance to thermosets made from the resins. 
As we described in copending application Ser. No. 08/228,845, carboxylic 
acids, including aromatic dicarboxylic acids, can be inserted in one step 
into polyethers using strong protic acids or their metal salts as 
catalysts. Examples 2 and 5 of that application illustrate the insertion 
process with 20 wt. % isophthalic acid. The examples show that it is 
possible to make polyetheresters having high aromatic ester content by a 
single-step insertion process. 
The single-step process illustrated by those examples has some 
disadvantages compared with the process of the invention when such high 
levels of aromatic dicarboxylic acids are used. First, relatively high 
catalyst levels (typically 1 wt. % or higher) are needed for the 
single-step insertion process to give satisfactory reaction rates. Second, 
the yield of polyetherester resin obtainable is somewhat less than 
desirable. Third, resin consistency is difficult to achieve with the 
single-step process. As the comparative examples (See C12-C14) in this 
application illustrate, the single-step insertion process may be too slow 
at desirable catalyst levels of less than about 0.5 wt. %. The reactions 
can be incomplete even after several days of heating at elevated 
temperature, and the products often become discolored. 
Thus, while at least about 10 wt. % of aromatic dicarboxylic acid content 
is desirable in polyetheresters to give them good mechanical properties 
and chemical resistance, the single-step insertion process is not 
completely satisfactory for making these products. 
Ordinary esterification procedures can be used to make polyetheresters. For 
example, one can react a low molecular weight polyol, a glycol, maleic 
anhydride, and isophthalic acid in a single-step cook to make a 
polyetherester. Unfortunately, thermosets made from this type of product 
often lack the desirable physical and mechanical properties available from 
polyetheresters made by an insertion process. We believe that the 
relatively slow reactivity of isophthalic acid compared with that of 
maleic anhydride in the ordinary esterification process adversely impacts 
the product. 
A valuable process would capitalize on the improved properties available 
from polyetheresters made by an insertion process, but would also 
facilitate the inclusion of more than about 10 wt. % of recurring units of 
an aromatic dicarboxylic acid in the polyetherester. Ideally, the process 
would be easy to perform at low catalyst levels, would give consistent 
resins, and would not require excessively long reaction times or high 
temperatures. 
SUMMARY OF THE INVENTION 
The invention is a two-step process for making polyetherester resins. 
First, a low molecular weight polyether polyol reacts with an aromatic 
dicarboxylic acid to produce a polyester intermediate. In step two, the 
polyester intermediate reacts with an anhydride or an aliphatic 
dicarboxylic acid in the presence of a catalyst effective to promote 
random insertion of the anhydride or dicarboxylic acid into polyether 
segments of the polyester intermediate. The resulting product is a 
polyetherester resin that contains greater than about 10 wt. % of 
recurring units derived from the aromatic dicarboxylic acid. 
Although polyetheresters having at least about 10 wt. % of recurring units 
derived from an aromatic dicarboxylic acid are difficult to make by the 
single-step insertion process, we surprisingly found that they can be made 
easily, even at low catalyst levels, with the two-step process of the 
invention. The resulting polyetheresters, which contain up to about 25 wt. 
% of recurring units derived from the aromatic dicarboxylic acid, are 
useful for making thermoset resins with excellent mechanical properties 
and chemical resistance. The invention includes polyetherester and 
glycol-capped polyetherester resins made by the process of the invention. 
Also included are polyetherester thermosets made from the resins. 
DETAILED DESCRIPTION OF THE INVENTION 
The process of the invention is used to make polyetherester resins in two 
steps. In step one, a low molecular weight polyether polyol reacts with an 
aromatic dicarboxylic acid to produce a polyester intermediate. 
By "low molecular weight polyether polyol" we mean polyether polyols having 
average hydroxyl functionalities from about 2 to about 8 and number 
average molecular weights less than about 2000. Preferred low molecular 
weight polyether polyols have average hydroxyl functionalities from about 
2 to about 3, and number average molecular weights within the range of 
about 200 to about 1000. Suitable low molecular weight polyols include, 
for example, polyoxypropylene polyols, polyoxyethylene polyols, ethylene 
oxide-propylene oxide copolymers, polytetramethylene ether glycols, 
oxetane polyols, and copolymers of tetrahydrofuran and epoxides. Suitable 
low molecular weight polyols include polyalcohols such as tripropylene 
glycol, glycerin, propoxylated glycerin, trimethylolpropane, and the like. 
Particularly preferred low molecular weight polyols are poly(oxypropylene) 
diols and trioIs. These are easily made according to well known methods by 
reacting a polyalcohol (glycerin, trimethylolpropane, propylene glycol, or 
the like) with propylene oxide in the presence of a basic catalyst. 
An aromatic dicarboxylic acid reacts with the low molecular weight 
polyether polyol. Suitable aromatic dicarboxylic acids are those commonly 
used in the polyester industry. Aromatic dicarboxylic acids are typically 
high-melting solids. Examples include phthalic acid, isophthalic acid, 
terephthalic acid, and halogenated derivatives of these. Isophthalic acid 
is particularly preferred. 
The relative proportions of aromatic dicarboxylic acid and low molecular 
weight polyether polyol are adjusted to provide up to about 2 moles of 
--COOH groups for each mole of --OH groups present. A preferred range is 
from about 0.5 to about 2 moles of --COOH groups per mole of --OH groups 
present. 
The low molecular weight polyether polyol and aromatic dicarboxylic acid 
are reacted by heating them together, optionally in the presence of an 
esterification catalyst, under conditions effective to promote 
esterification of the polyol hydroxyl end groups. The reaction temperature 
is preferably within the range of about 150.degree. C. to about 
250.degree. C.; a more preferred range is from about 180.degree. C. to 
about 220.degree. C. The reaction is normally complete within about 6 to 8 
h at temperatures within the more preferred range. As the reaction 
proceeds, the reaction mixture usually turns from opaque to clear as the 
aromatic dicarboxylic acid melts or dissolves and reacts with the 
polyether polyol. 
If desired, an esterification catalyst is included. Suitable esterification 
catalysts will promote reaction of polyol hydroxyl end groups with 
aromatic dicarboxylic acids to produce polyols capped with aromatic 
dicarboxylic acids. Suitable esterification catalysts include, for 
example, organic sulfonic acids such as p-toluenesulfonic acid. Often, an 
esterification catalyst is omitted. 
The product from step one is a polyester intermediate. The polyester 
intermediate will typically have mostly aromatic acid terminal groups. The 
progress of the reaction is normally followed simply by observing the 
transition from an opaque to a clear reaction mixture. If desired, 
however, one can monitor the acid number of the reaction mixture and 
proceed to step two when the acid number reaches a targeted value. 
In step two, the polyester intermediate reacts with an anhydride or an 
aliphatic dicarboxylic acid in the presence of a catalyst effective to 
promote random insertion of the anhydride or dicarboxylic acid into 
polyether segments of the polyester intermediate (an "insertion 
catalyst"). The resulting product is a polyetherester resin that contains 
greater than about 10 wt. % of recurring units derived from the aromatic 
dicarboxylic acid. 
Anhydrides suitable for use are cyclic anhydrides. Saturated anhydrides, 
unsaturated anhydrides, or mixtures thereof can be used. If the resin is 
to be used for making a thermoset polyetherester resin, then at least a 
portion--and preferably most--of the anhydride must be unsaturated. 
Unsaturated anhydrides contain ethylenic unsaturation. Suitable 
unsaturated anhydrides include, for example, maleic anhydride, citraconic 
anhydride, itaconic anhydride, halogenated unsaturated anhydrides, and the 
like, and mixtures thereof. Maleic anhydride is particularly preferred. 
Suitable saturated anhydrides (which contain no reactive ethylenic 
unsaturation) include, for example, succinic anhydride, alkyl-substituted 
succinic anhydrides, phthalic anhydride, and the like, and mixtures 
thereof. Polyetheresters prepared using only saturated anhydrides are 
particularly useful as polyester polyol intermediates for polyurethanes. 
Aliphatic dicarboxylic acids useful in the invention include linear, 
branched, and cycloaliphatic saturated and unsaturated compounds that 
contain two --COOH groups. Preferred dicarboxylic acids are C.sub.3 
-C.sub.40 aliphatic dicarboxylic acids. Suitable dicarboxylic acids 
include, for example, adipic acid, suberic acid, malonic acid, azelaic 
acid, sebacic acid, maleic acid, fumaric acid, citraconic acid, glutaric 
acid, succinic acid, 1,4-cyclohexanedicarboxylic acid, and the like, and 
mixtures thereof. Saturated C.sub.4 -C.sub.20 aliphatic dicarboxylic acids 
are particularly preferred. 
The polyester intermediate reacts with the anhydride or aliphatic 
dicarboxylic acid in the presence of a catalyst that promotes random 
insertion of the anhydride or dicarboxylic acid into polyether segments of 
the polyester intermediate (an "insertion catalyst"). Suitable insertion 
catalysts include Lewis acids, protic acids that have a pKa less than 
about 0, and metal salts of the protic acids. The insertion catalyst is 
used in an amount effective to promote random insertion of either the 
anhydride or the aliphatic dicarboxylic acid into polyether carbon-oxygen 
bonds of the polyester intermediate. 
Preferred Lewis acids are metal halides of the formula MX.sub.n, wherein M 
is a metal having an oxidation number from 2 to 4, X is a halogen, and n 
is an integer from 2 to 4. Examples of suitable Lewis acids are zinc 
chloride, zinc bromide, stannous chloride, stannous bromide, aluminum 
chloride, ferric chloride, boron trifluoride, and the like, and mixtures 
thereof. Most preferred are zinc chloride and zinc bromide. When a Lewis 
acid catalyst is used, it is preferred to use an amount within the range 
of about 0.01 to about 5 wt. % based on the amount of polyester 
intermediate. Additional examples of suitable Lewis acids are found in 
U.S. Pat. No. 5,319,006, the teachings of which are incorporated herein by 
reference. 
Protic acids (organic and inorganic) that have a pKa less than about 0 are 
also useful as insertion catalysts. Generally, the acids will be stronger 
than organic carboxylic acids. Suitable acids include arylsulfonic acids, 
alkylsulfonic acids, and halogenated alkyl- and arylsulfonic acids. Also 
suitable are hydrogen halides, halosulfonic acids, tetrafluoroboric acid, 
heteropolyacids, and sulfuric acid. Mixtures of different acids can be 
used. Examples include p-toluenesulfonic acid, trifluoromethanesulfonic 
acid (triflic acid), trichloromethanesulfonic acid, hydrochloric acid, 
phosphotungstic acid, and the like. Preferred protic acids are sulfuric 
acid, p-toluenesulfonic acid, and phosphotungstic acid. When a protic acid 
is used as the catalyst, it is generally preferred to use an amount within 
the range of about 0.01 to about 1 wt. % based on the amount of polyester 
intermediate. A more preferred range is from about 0.01 to about 0.3 wt. 
%. Additional examples of suitable protic acids are found in application 
Ser. No. 08/220,149, filed Mar. 30, 1994, now allowed, the teachings of 
which are incorporated herein by reference. 
Metal salts derived from protic acids that have a pKa less than about 0 are 
also effective insertion catalysts. Preferred salts are metal salts of 
arylsulfonic acids, alkylsulfonic acids, halogenated aryl- and 
alkylsulfonic acids, tetrafluoroboric acid, sulfuric acid, 
heteropolyacids, and halosulfonic acids. Sulfonic acid salts, especially 
triflate salts, are particularly preferred. Preferably, the metal is 
selected from Group IA, IIA, IIB, IB, IIIA, IVA, VA, and VIII. Thus, the 
metal can be, for example, lithium, potassium, magnesium, zinc, copper, 
aluminum, tin, antimony, iron, nickel. Examples of suitable metal salts 
are lithium triflate, sodium triflate, magnesium triflate, zinc triflate, 
copper(II) triflate, zinc tetrafluoroborate, zinc p-toluenesulfonate, 
aluminum triflate, iron(II) tetrafluoroborate, tin(II) triflate, and the 
like, and mixtures thereof. When a metal salt is used as the catalyst, it 
is preferably used in an amount within the range of about 1 part per 
million (10.sup.-4 wt. %) to about 1 wt. % based on the amount of 
polyester intermediate. A more preferred range is from about 0.01 wt. % to 
about 0.3 wt. %. Additional examples of suitable metal salts of protic 
acids are found in application Ser. No. 08/220,149, filed Mar. 30, 1994, 
now allowed, the teachings of which are incorporated herein by reference. 
The polyester intermediate and anhydride or aliphatic dicarboxylic acid are 
reacted by heating them together in the presence of the insertion catalyst 
under conditions effective to promote insertion of the anhydride or 
aliphatic dicarboxylic acid into polyether segments of the polyester 
intermediate. The reaction temperature is preferably within the range of 
about 80.degree. C. to about 250.degree. C.; a more preferred range is 
from about 100.degree. C. to about 220.degree. C. The reaction is normally 
complete within about 8 h at temperatures within the more preferred range. 
The resulting product is a polyetherester resin that contains greater than 
about 10 wt. % of recurring units derived from the aromatic dicarboxylic 
acid. The polyetherester resin preferably contains from about 10 to about 
25 wt. % of recurring units derived from the aromatic dicarboxylic acid; 
most preferred is the range from about 15 to about 25 wt. %. 
Heating continues to produce a polyetherester resin that preferably has an 
acid number within the range of about 75 to about 200 mg KOH/g; a more 
preferred range is from about 90 to about 150 mg KOH/g; most preferred is 
the range from about 110 to about 130 mg KOH/g. 
The polyetherester resin prepared as described above commonly has a large 
proportion of carboxylic acid end groups. This resin can be used "as is" 
to make a polyetherester thermoset. Preferably, it is modified in one of 
two ways before using it to make a polyetherester or polyurethane. One way 
to modify the resin is to continue heating it to further react the polymer 
and reduce its acid number, preferably to about 60 mg KOH/g or less. This 
method is generally the less desirable of the two because excessive 
heating and prolonged reaction times are needed to achieve a resin having 
a low enough acid number. The second and more preferred method, which is 
described further below, is to reduce the acid number by heating the 
polyetherester resin in the presence of a glycol. 
The polyetherester resin having an acid number within the range of about 75 
to about 200 mg KOH/g is preferably heated with a glycol to produce a 
glycol-capped polyetherester resin that has a reduced acid number. 
Suitable glycols have molecular weights less than about 200. Suitable 
glycols include, for example, propylene glycol, ethylene glycol, 
diethylene glycol, dipropylene glycol, tripropylene glycol, 
1,4-butanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, neopentyl 
glycol, and the like, and mixtures thereof. Particularly preferred are 
propylene glycol, neopentyl glycol, and 2-methyl-1,3-propanediol. 
The amount of glycol used is preferably at least about 1 equivalent of 
glycol for each residual carboxylic acid end group. Typically, this 
amounts to heating the polyetherester resin with at least about 5-20 wt. % 
of the glycol. The glycol is typically heated with the polyetherester 
resin at the same temperature as that used for the insertion reaction 
until the acid number of the glycol-capped polyetherester resin drops to 
the desired level. Any excess glycol is removed by stripping. 
The polyetherester resin is preferably heated in the presence of the glycol 
to produce a glycol-capped polyetherester resin that has an acid number 
within the range of about 30 to about 90 mg KOH/g; a more preferred range 
is from about 40 to about 60 mg KOH/g. 
Polyetherester resins and glycol-capped polyetherester resins of the 
invention that contain some ethylenic unsaturation are useful for 
preparing polyetherester thermosets. The thermoset is made by reacting a 
resin of the invention with a vinyl monomer in the presence of a 
free-radical initiator under conditions effective to produce a 
polyetherester thermoset. The techniques are essentially the same as those 
used in the polyester industry to prepare unsaturated polyester thermosets 
from unsaturated polyester resins. 
A vinyl monomer is used to make the polyetherester thermosets of the 
invention. Preferred vinyl monomers are vinyl aromatic monomers, 
acrylates, methacrylates, and allyl esters. Suitable vinyl monomers 
include, for example, styrene, methyl methacrylate, methyl acrylate, 
diallyl phthalate, divinylbenzene, .alpha.-methylstyrene, and the like, 
and mixtures thereof. Styrene is particularly preferred. 
The polyetherester resins are often blended with a vinyl monomer (typically 
styrene) and an inhibitor such as hydroquinone, tert-butylcatechol, or the 
like, or mixtures thereof, and the solution is stored until needed. 
The polyetherester resin solution can be used to make a clear casting by 
combining it with a free-radical initiator, preferably a peroxide such as 
benzoyl peroxide, tert-butylperbenzoate, or the like, pouring the mixture 
into a mold, and heating it to effect a cure. If desired, other additives 
can be included in the thermosets, including, for example, fillers, 
pigments, chopped glass, glass mat, low-profile additives, flame 
retardants, and the like. 
The process of the invention offers significant advantages. While 
polyetheresters having at least about 10 wt. % of recurring units derived 
from an aromatic dicarboxylic acid are difficult to make by a single-step 
insertion process, they can be easily made by the two-step process of the 
invention. The process of the invention gives complete reactions using low 
catalyst levels in a matter of hours; the insertion-only process is often 
incomplete days later. In addition, the process gives polyetherester 
resins of consistent quality. 
The polyetherester products made by the process of the invention exhibit 
good mechanical properties and chemical resistance, as might be expected 
of isophthalate polyesters. (Compare Examples 1-4 with Comparative Example 
5). Surprisingly, however, thermoset resins made from the polyetheresters 
of the invention outperform those made from polyetheresters made using 
only an esterification process. (Compare Examples 1-3 with Comparative 
Examples 6-8). In particular, the tensile strengths of the thermosets made 
from the polyetherester resins of the invention far exceed those of 
thermosets made from polyetheresters made by a one-step esterification 
procedure, particularly in the 15-20 wt. % isophthalic acid range. These 
results highlight the advantage of using a polyetherester resin made at 
least in part by an insertion process. 
As Comparative Examples 12-14 show, however, an insertion process alone is 
not satisfactory. Attempted preparation of a polyetherester resin by an 
insertion process alone using 0.3-0.5 wt. % p-toluenesulfonic acid 
catalyst and from 15-20 wt. % of isophthalic acid is not successful. Even 
after about 20 hours at 185.degree.-195.degree. C., much of the 
isophthalic acid remains unreacted. On the other hand, use of the two-step 
process of the invention facilitates the preparation of a product 
containing 20 wt. % or more of recurring units derived from isophthalic 
acid (see Examples 1, 10, and 11).

The following examples merely illustrate the invention. Those skilled in 
the art will recognize many variations that are within the spirit of the 
invention and scope of the claims. 
EXAMPLE 1 
Preparation of a Polyetherester Resin by Esterification/Insertion and 
Preparation of a Polyetherester Thermoset from the Resin. 
A two-liter resin kettle is charged with a 400 mol. wt. poly(oxypropylene) 
diol (900 g), isophthalic acid (300 g, 20%), and p-toluenesulfonic acid 
(1.5 g). The mixture is heated to 195.degree. C. and is maintained at that 
temperature for 6 h or until the mixture becomes clear. Maleic anhydride 
(300 g, 20%) is added, and the mixture is heated at 185.degree. C. Heating 
continues until the acid number drops to 120 mg KOH/g. Propylene glycol 
(180 g) is added, and heating continues. About 4 h after the glycol is 
added, the acid number of the resin drops to 55 mg KOH/g. The product is 
allowed to cool to about 120.degree. C. and 100 ppm of hydroquinone is 
added. The resin (60 wt. %) is then blended with styrene (40 wt. %) that 
contains methylhydroquinone (100 ppm) and tert-butylcatechol (50 ppm) 
inhibitors. 
The polyetherester resin solution is used to make a clear casting as 
follows. Benzoyl peroxide (1.3 wt. %) and tert-butylperbenzoate (0.3 wt. 
%) are combined with the resin/styrene solution. The mixture is poured 
into a mold, and is heated at 55.degree. C. overnight, then at 75.degree. 
C. for 2 h, at 105.degree. C. for 2 h, and finally at 135.degree. C. for 2 
h. The product is a polyetherester thermoset that has the properties shown 
in Table 1. 
EXAMPLES 2-4 
Preparation of Polyetherester Resins by Esterification/Insertion and 
Preparation of Polyetherester Thermosets from the Resins. 
The procedure of Example 1 is followed to make additional polyetherester 
resins by the two-step esterification/insertion process of the invention. 
The amounts of maleic anhydride and isophthalic acid used to make the 
resins is varied as indicated in Table 1. The resins are cured with 
styrene to make polyetherester thermosets. Properties of the 
polyetherester thermosets are shown in Table 1. 
Comparative Example 5 
The procedure of Example 1 is generally followed, except that isophthalic 
acid is omitted from the formulation. The polyether diol is simply heated 
at 185.degree. C. with maleic anhydride (300 g, 20%). The resin is cured 
with styrene as described in Example 1. The properties of the 
polyetherester thermoset appear in Table 1. 
This example illustrates that thermosets having much higher tensile and 
flexural strengths are available by including isophthalic acid recurring 
units in the polyetherester resin. 
Preparation of Polyetherester Resins by Esterification Only (Comparative 
Examples 6-8) 
Comparative Example 6 
A two-liter resin kettle is charged with a polyoxypropylene diol of about 
400 mol. wt. (649 g), isophthalic acid (320 g), maleic anhydride (320 g), 
and propylene glycol (311 g). The mixture is heated to 195.degree. C. and 
is held at that temperature until more than 95% of the water of reaction 
is collected or until the acid number drops to 60 mg KOH/g or less (24-35 
h). The mixture is heated at 195.degree. C. under vacuum (20-50 mm Hg) 
until the acid number drops to less than 40 mg KOH/g. The product is 
cooled to about 120.degree. C., and hydroquinone (100 ppm) is added. The 
resin is then blended 60/40 (wt/wt) with styrene that contains 
methylhydroquinone (100 ppm) and tert-butylcatechol (50 ppm) as 
inhibitors. The resin solution is used to make a clear thermoset casting 
as described in Example 1. Physical properties of the casting appear in 
Table 1. 
Comparative Example 7 
The procedure of Comparative Example 6 is used to make a polyetherester 
resin by esterification only that contains 15% isophthalic acid and 20% 
maleic anhydride recurring units. The amounts of reagents are adjusted as 
follows: polyoxypropylene diol of about 400 mol. wt. (797 g); isophthalic 
acid (240 g); maleic anhydride (320 g); propylene glycol (243 g). The 
resin solution is used to make a clear thermoset casting as described in 
Example 1. Physical properties of the casting appear in Table 1. 
Comparative Example 8 
The procedure of Comparative Example 6 is used to make a polyetherester 
resin by esterification only that contains 10% isophthalic acid and 20% 
maleic anhydride recurring units. The amounts of reagents are adjusted as 
follows: polyoxypropylene diol of about 400 mol. wt. (946 g); isophthalic 
acid (160 g); maleic anhydride (320 g); propylene glycol (174 g). The 
resin solution is used to make a clear thermoset casting as described in 
Example 1. Physical properties of the casting appear in Table 1. 
EXAMPLES 9-11 
Preparation of Polyetherester Resins by Esterification/Insertion and 
Preparation of Polyetherester Thermosets from the Resins. 
The procedure of Example 1 is followed to make polyetherester resins from 
15-25 wt. % isophthalic acid (see Table 2). The resins (60 wt. %) are then 
blended with styrene (40 wt. %) that contains methylhydroquinone (100 ppm) 
and tert-butylcatechol (50 ppm) inhibitors. 
Each polyetherester resin solution is used to make a clear casting as 
follows. The resin solution is mixed with cobalt naphthenate (0.2-0.5 wt. 
%) and methyl ethyl ketone peroxide (1-1.5 wt. %). The solution is poured 
into a mold, and is cured at room temperature overnight. The product is 
post-cured by heating it further at 100.degree. C. for 5 h. The product is 
a polyetherester thermoset that has the properties shown in Table 2. 
Comparative Example 12 
Attempted Preparation of a 20% Isophthalic Acid/20% Maleic Anhydride 
Polyetherester Resin by an Insertion Process Only 
A 3000 mol. wt. poly(oxypropylene) triol (900 g), maleic anhydride (300 g), 
and isophthalic acid (300 g), and p-toluenesulfonic acid (3.0 g) are 
charged to a two-liter resin kettle, and the mixture is heated at 
195.degree. C. for 6 h. More p-toluenesulfonic acid (3.0 g) is added, and 
the mixture is heated at 195.degree. C. for 16 more hours. The reaction 
mixture became dark and was still cloudy because much of the isophthalic 
acid had not reacted. The reaction was aborted. 
Comparative Example 13 
Attempted Preparation of a 20% Isophthalic Acid Polyetherester Resin by an 
Insertion Process Only 
A two-liter resin kettle is charged with a polyoxypropylene diol (2000 mol. 
wt., 1400 g), isophthalic acid (351 g), and p-toluenesulfonic acid (8.9 
g). The mixture is heated to 185.degree. C. with vigorous stirring. After 
approximately 18 h of heating, the mixture still contains much unreacted 
isophthalic acid, which is present as a white solid. At this point, the 
mixture darkens significantly. Within a few hours it becomes dark brown 
and is discarded. 
Comparative Example 14 
Attempted Preparation of a 15% Isophthalic Acid Polyetherester Resin by an 
Insertion Process Only 
A three-liter resin kettle is charged with a 3000 mol. wt. polyoxypropylene 
triol (1934 g), isophthalic acid (342 g), and p-toluenesulfonic acid (6.8 
g). The mixture is heated to 185.degree. C. with vigorous stirring. After 
18.5 h of heating, the acid number of the still-cloudy mixture falls to 45 
mg KOH/g. Propylene glycol (70 g) is added, and heating continues for 
another 5 h. The reaction mixture discolors, so heating is stopped, 
although solid is still present. Proton NMR analysis shows that the solid 
is unreacted isophthalic acid. 
Comparative Examples 12-14 show that polyetherester resins that contain 
about 15-20 wt. % of recurring units derived from isophthalic acid are not 
easily made by single-step insertion of isophthalic acid into a polyether 
polyol at desirable catalyst levels of 0.1-0.5 wt. %. On the other hand, 
these products are readily made by the two-step esterification/insertion 
process of the invention. 
TABLE 1 
__________________________________________________________________________ 
Properties of Polyetherester Thermosets: 
Isophthalate Polyetherester Resins (40 wt. % Styrene) 
Tensile 
Elongation 
Tensile 
Flexural 
Flexural 
Ex. IPA/MA 
strength 
at break 
modulus 
strength 
modulus 
# (wt. %) 
(psi) 
(%) (ksi) 
(psi) (ksi) 
__________________________________________________________________________ 
1 20/20 
9200 3.0 450 13800 495 
2 15/20 
5700 8.1 351 13300 376 
3 10/20 
3250 25 215 7800 231 
4 15/25 
9800 3.0 470 17300 514 
C5 0/20 
1970 41 58 2340 74 
C6 20/20 
5100 10 307 11500 313 
C7 15/20 
4345 11 266 8950 255 
C8 10/20 
3410 20 207 7180 211 
__________________________________________________________________________ 
IPA = isophthalic acid; 
MA = maleic anhydride. 
Clear castings are made by mixing the polyetherester resin/styrene 
solutions with benzoyl peroxide (1.3 wt. %) and tertbutylperbenzoate (0.3 
wt. %). The mixture is poured into a mold, and is heated at 55.degree. C. 
overnight, then at 75.degree. C. for 2 h, at 105.degree. C. for 2 h, and 
finally at 135.degree. C. for 2 h. 
Tensile and flex properties are measured using standard ASTM methods D638 
and D790. 
TABLE 2 
__________________________________________________________________________ 
Properties of Polyetherester Thermosets: 
Isophthalate Polyetherester Resins (40 wt. % Styrene) 
Tensile 
Elongation 
Tensile 
Flexural 
Flexural 
Ex. IPA/MA 
strength 
at break 
modulus 
strength 
modulus 
# (wt. %) 
(psi) 
(%) (ksi) 
(psi) (ksi) 
__________________________________________________________________________ 
9 15/30 
10540 
3.8 491 19750 524 
10 20/25 
8470 2.3 525 19430 509 
11 25/20 
6300 7.6 414 16640 461 
__________________________________________________________________________ 
IPA = isophthalic acid; 
MA = maleic anhydride. 
Clear castings are made by mixing the polyetherester resin/styrene 
solution with cobalt naphthenate (0.2-0.5 wt. %) and methyl ethyl ketone 
peroxide (1-1.5 wt. %). The solution is poured into a mold, and is cured 
at room temperature overnight. The product is postcured by heating it 
further at 100.degree. C. for 5 h. 
Tensile and flex properties are measured using standard ASTM methods D638 
and D790. 
The preceding examples are meant only as illustrations; the following 
claims define the invention.