Polyester-flexible polymer block copolymers and mixtures thereof

A block copolymer of generally an AB, ABA, or A(BA).sub.n structure, or mixtures thereof where the A block is an unsaturated polyester, the B block is a flexible polymer having a Tg of 0.degree. C. or lower, and n is 2 to 5. The various block components are generally first separately prepared as polymers with the flexible polymer generally having 1 or 2 functional end groups such as an amine group, a carboxyl group, or a hydroxyl group with the later being preferred. Alternatively, for low molecular weight unsaturated polyester blocks, the block can be made in situ. The preferred reaction route is to react a mono or dihydroxy terminated flexible polymer with a diisocyanate which subsequently can be readily reacted with the polyester. The block copolymers can be utilized as toughening agents. They furthermore can be utilized to coat a fiber structure such as individual fibers, a woven structure, or a nonwoven structure such as mats, rovings, bundles, and the like, with the coated fiber structures subsequently incorporated into a polymeric matrix such as polyester.

FIELD OF THE INVENTION 
The present invention relates to a polyester-flexible polymer block 
copolymer having an unsaturated high amount by weight of the flexible 
polymer segment therein. 
BACKGROUND 
Heretofore, copolymers of polyester and elastomer have generally been made 
by polymerizing ester-forming monomers including mixtures of elastomeric 
prepolymers with ester-forming monomers, the result being the formation of 
a random polyester-elastomer copolymer containing elastomer segments 
therein. The structures of such copolymers are generally difficult to 
control and can be the result of side reactions, such as branching. 
SUMMARY OF THE INVENTION 
The present invention relates to block copolymers generally of the ABA or 
AB structure or mixtures thereof where the B block is a flexible polymer 
or segment having a Tg of generally 0.degree. C. or less and preferably 
below minus 20.degree. C. The flexible block generally has one or two 
hydroxyl end groups, amine end groups, or carboxylic end groups and thus 
is monofunctional or difunctional. The A block is generally a specific 
class of unsaturated polyesters preferably having only a mono-, or less 
desirably a di-, hydroxyl, carboxylic, or amine end group. The polyester A 
block is generally linked to the flexible polymer B block through an 
ester, an amide, a urea, or a urethane group. A preferred linkage is a 
urethane linkage formed by reacting a hydroxyl terminated B flexible 
polymer with a diisocyanate and subsequently reacting the same with a 
monohydroxyl terminated A polyester. Alternatively, the hydroxy-terminated 
B polymer can be reacted with a cyclic anhydride and an oxirane using 
specific catalysts to give an ABA block copolymer. The copolymers of the 
present invention are true block copolymers in that they generally contain 
linear AB or ABA type structure and generally have little, if any, chain 
extension or branching structure, and may contain minor amounts of 
A(BA).sub.n type block copolymers where n is 2 to 5, preferably 2. 
DETAILED DESCRIPTION 
The B portion of the block copolymers of the present invention can 
generally be any flexible polymer. Such flexible polymers are generally 
defined as any polymer which has a Tg of about 0.degree. C. or less and 
preferably below minus 20.degree. C., often are liquid, and are readily 
known in the art and to the literature, including the preparation thereof. 
One such class of flexible polymers is made from one or more various 
conjugated diene monomers having from 4 to 12 carbon atoms, desirably from 
4 to 8 carbon atoms with 4 or 5 carbon atoms being preferred. Examples of 
specific dienes include butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 
pentadiene, hexadiene, 4,5-diethyl-1,3-octadiene, and the like, with 
butadiene and isoprene being preferred. The structure of such conjugated 
dienes is generally such that it has a Tg within the above-noted ranges. 
Such polymers are terminated with either one or two functional end groups 
wherein the functional end group is hydroxyl, amine, or carboxyl. Thus, 
the B block can be a mono- or di- hydroxyl terminated flexible polymer, a 
mono or diamine terminated flexible polymer, or a mono- or di- carboxyl 
terminated flexible polymer. Such polymers are well-known to the art and 
are commercially available as from the BFGoodrich Chemical Co., under the 
Hycar.RTM. trademark. 
Another class of the B block flexible polymer is the various hydrogenated 
dienes or polyolefins which are mono or di-hydroxyl, carboxyl, or amine 
terminated. Such polymers, as well as the preparation thereof, are well 
known to the art and to the literature. Typical diene polymers are made 
from one or more conjugated dienes, having from 4 to 10 carbon atoms, such 
as 1,3-butadiene, isoprene, dimethyl butadiene, and the like. The 
polymerization of the diene monomer, typically, may be done via anionic 
initiation (e.g. with di-lithium hydrocarbyl initiators) or via 
free-radical polymerization, e.g. by initiation with hydrogen peroxide, 
which also introduces hydroxy end groups. In case of anionic 
polymerization, OH-end groups are advantageously introduced by reaction of 
the polymeric carbanion chain ends with ethylene oxide. These techniques 
are generally well known to the literature. The hydroxy-functional 
polydienes may be hydrogenated, for example, partially or substantially 
(i.e., at least 50, 70, or 90 percent of the unsaturated sites), and even 
completely hydrogenated, according to any conventional method known to the 
art and to the literature. Complete hydrogenation of various diene 
polymers such as 1,4-polyisoprene is equivalent to an alternating 
ethylene/propylene hydrocarbon polymer. The hydrocarbon polymers generally 
have a number average molecular weight from about 500 to 15,000 and 
preferably from about 1,000 to about 8,000. The polymers are desirably 
liquid at room temperature, but can have a melting point up to about 
80.degree. C. Preferred polymers are hydroxyl functional telechelic, 
hydrogenated diene polymers containing 2 to 6 and preferably 2 to 4 
hydroxy end groups per polymeric molecule (polymer unit). 
An especially preferred hydrogenated butadiene polymer is commercially 
available as Polytail H and Polytail HA sold by Mitsubishi Kasei Corp., 
and has the very generalized structure: 
##STR1## 
wherein X and Y are randomly distributed and the structure can contain 
additional --OH groups. 
The hydroxyl, carboxylic or amine terminated polyolefins are generally made 
from one or more olefins having from 2 to 6 carbon atoms such as ethylene, 
propylene, butylene, and the like. Such functional polyolefins can also be 
made by utilizing minor amounts (i.e., up to about 50 mole percent and 
preferably up to 20 mole percent) of ethylenically unsaturated comonomers 
such as styrene, vinyl toluene, alpha-methylstyrene, divinylbenzene, and 
similar aromatic monomers; or vinyl monomers, such as acrylonitrile, 
methacrylonitrile, vinylidene chloride, and similar aliphatic vinyl 
monomers; or hydroxyl functional ethylenically unsaturated monomers such 
as 2-hydroxyl ethyl acrylate and methacrylate, 2-hydroxy propyl acrylate 
and methacrylate and similar hydroxy alkyl acrylates. Regardless of the 
type of polyolefin, it should contain either one or two hydroxyl groups 
per average molecule. 
Still another class of the B block flexible polymer is the various mono- or 
di- hydroxyl, amine, or carboxyl terminated nitrile containing copolymers. 
These copolymers are prepared in accordance with conventional techniques 
well known to the art and to the literature and are generally made from 
one or more monomers of acrylonitrile or an alkyl derivative thereof with 
one or more conjugated dienes and optionally one or more monomers of 
acrylic acid, or an ester thereof. Examples of acrylonitrile monomers or 
alkyl derivatives thereof include acrylonitrile and alkyl derivatives 
thereof having from 1 to 4 carbon atoms such as methacrylonitrile, and the 
like. The amount of the acrylonitrile or alkyl derivative monomer is from 
about 1 percent to about 50 percent by weight and preferably from about 5 
percent to about 35 percent by weight based upon the total weight of the 
nitrile containing copolymer. 
The conjugated diene monomers generally have from 4 to 10 carbon atoms with 
from 4 to 6 carbon atoms being preferred. Examples of specific conjugated 
diene monomers include butadiene, isoprene, hexadiene, and the like. The 
amount of such conjugated dienes is generally from about 50 percent to 
about 99 percent by weight and preferably from about 55 percent to about 
75 percent by weight based upon the total weight of the nitrile rubber 
forming monomers. Such mono or difunctional nitrile rubbers can be readily 
prepared generally containing either hydroxyl or carboxyl end groups and 
are known to the art and to the literature and are commercially available 
such as from The BFGoodrich Company under the tradename Hycar. 
Yet another class of the B block flexible polymers is the various 
copolymers made from vinyl substituted aromatics having from 8 to 12 
carbon atoms and conjugated diene monomers generally having from 4 to 12 
carbon atoms, desirably from 4 to 8 carbon atoms, and preferably 4 or 5 
carbon atoms. Examples of suitable aromatic monomers include styrene, 
alphamethyl styrene, and the like, with specific examples of conjugated 
dienes including hexadiene, isoprene, butadiene, and the like. A preferred 
copolymer is a random styrene butadiene copolymer. The amount of the vinyl 
substituted aromatic component, such as styrene, is generally from about 
one part to about 50 parts, and desirably from about 1 part to about 30 
parts by weight, based upon the total weight of the copolymer. The 
preparation of such polymers having mono or di- hydroxyl, amine, or 
carboxyl terminated vinyl substituted aromatic conjugated diene copolymer 
are well known to the art and to the literature. 
A still further class of the B block flexible polymers is the various 
polyethers which are either mono- or di- hydroxyl, amine, or carboxyl 
terminated. Such polyether polyols are generally made by reacting one or 
more alkylene oxides having from 2 to 10 or 20 carbon atoms such as 
propylene oxide with a strong base such as potassium hydroxide, preferably 
in the presence of water, glycols and so forth. Polyether polyols can also 
be made by ring opening polymerization of tetrahydrofuran or 
epichlorohydrin using acid catalysts. Examples of polyethers which can be 
utilized are those which are produced as by polymerization of 
tetrahydrofuran or epoxides (such as ethylene oxide, propylene oxide, 
butylene oxide, styrene oxide, or epichlorohydrin), or by addition of 
epoxide compounds (preferably ethylene oxide or propylene oxide), alone, 
in a mixture, or in succession, to starting components with reactive 
hydrogen atoms such as water, polyhydric alcohols, ammonia, or 
polyfunctional amines. The above mono- or di-hydroxyl, amine, or carboxyl 
terminated polyethers, as well as the preparation thereof, are well known 
to the art and are commercially available. Hydroxy terminated 
polytetrahydrofurans are commercially available as from DuPont as 
Terethane. Hydroxy terminated polypropylene oxides are commercially 
available as from Dow Chemical as Voranol and amine terminated polyethers 
are commercially available as from Texaco as Jeffamine. 
Still another class of the B block flexible polymers is the various 
saturated polyesters made from aliphatic dicarboxylic acids or aliphatic 
anhydrides and glycols, and such are well known to the art and to the 
literature, as is the preparation thereof, and are commercially available. 
The aliphatic dicarboxylic acids and anhydrides have from 1 to 10 carbon 
atoms, with specific examples including carbonic acid, malonic acid, 
succinic, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic 
acid, sebacic acid, the anhydride counterparts thereof, and the like, with 
adipic acid generally being preferred. Optionally included within the 
above aliphatic dicarboxylic acids are minor amounts, that is up to 20 
percent by weight based upon a total weight of the acids, of an aromatic 
diacid such as phthalic acid, isophthalic acid, terephthalic acid, and the 
like. Mixtures of all of the above acids can be utilized as well. The 
glycols generally have from 2 to 15 carbon atoms with specific examples 
including ethylene glycol, propylene glycol, 1,3-butylene glycol, 
1,4-butylene glycol, pentane diol, hexane diol, cyclohexanedimethanol 
dipropylene glycol, diethylene glycol, pinacol, and the like. Preferred 
glycols include diethylene glycol or a mixture of propylene glycol with 
ethylene glycol. 
The polyester or A block is generally an unsaturated polyester having an 
average molecular weight of between 100 or 500 to 2,000 or 5,000 and has 
one, or less desirably two, functional end groups thereon such as 
hydroxyl, carboxyl, or amine. The polyesters are made by the 
copolymerization of generally cyclic ethers typically containing 2 or 3 
carbon atoms in the ring and an unsaturated anhydride, as well as optional 
saturated anhydrides using double metal complex cyanide catalysts. 
Generally any cyclic oxide can be utilized such as 1,2-epoxides, oxetanes, 
and the like, with the cyclic ether having a total of up to 18 carbon 
atoms, as for example 2 carbon atoms in the ring and up to 16 carbon atoms 
in the side chains. Such cyclic oxide monomers can also contain one or 
more aliphatic double bonds and preferably only contain one aliphatic 
carbon to carbon double bond. Examples of suitable cyclic oxides include 
ethylene oxide (1,2-epoxy ethane), 1,2-propylene oxide, 1,2-butene oxide, 
1,2-hexene oxide, 1,2-dodecane monoxide, isobutylene oxide, styrene oxide, 
1,2-pentene oxide, isopentene oxide, 1,2-heptene oxide, allyl gylcidyl 
ether, isoheptene oxide, 1,2-octene oxide, methyl glycidyl ether, ethyl 
glycidyl ether, phenyl glycidyl ether, butadiene monoxide, isoprene 
monoxide, styrene oxide, tolyl glycidyl ether, 1,2-pentadecene oxide, 
epichlorohydrin, glycidoxypropyltrimethoxysilane, and the like. Generally, 
ethylene oxide, propylene oxide, and butylene oxide are preferred. 
Generally anhydrides having a total of from 4 to 20 carbon atoms are 
utilized and five-member cyclic anhydrides are preferred, especially those 
having a molecular weight between 98 and 400. Mixed anhydrides as well as 
mixtures of anhydrides may be used. Examples of preferred anhydrides 
include those of maleic, phthalic, itaconic, nadic, methyl nadic, 
hexahydrophthalic, succinic, tetrahydrophthalic, 
1,2-naphthalenedicarboxylic, 1,2-tetrahydronaphthalene dicarboxylic acids, 
and the like. Further examples include such anhydrides in which hydrogen 
atoms have been substituted by halogen, hydroxyl or C.sub.1-8 carbon atom 
alkyl, aryl or aralkyl groups such as the anhydrides of 
3,4-dichlorophthalic, hexachlorodicycloheptadiene dicarboxylic 
(chlorendic), 8-hydroxyl-1,2-naphthalenedicarboxylic, 2,3-dimethyl maleic, 
2-octyl-3-ethyl maleic, 4,5-dimethyl phthalic, 2-phenylethyl maleic, 
2-tolyl maleic and the like. 
As noted above, mixtures of saturated and unsaturated anhydrides can be 
utilized with generally maleic anhydride being preferred. Such polyesters 
are known to the art and to the literature and are generally made 
utilizing double metal cyanide complex catalysts. The method, preparation 
and scope of the various types of unsaturated polyesters which are 
suitable in the present invention are described in U.S. Pat. No. 3,538,043 
which is hereby fully incorporated by reference with regard to all aspects 
thereof. For example, suitable catalysts for preparation of the polyester 
A block include zinchexacyanocobaltate and analogs thereof as well as 
various metalloporphyrins. Reaction temperatures generally include ambient 
to about 130.degree. C. with from about 40.degree. to about 80.degree. C. 
being preferred. Such polyesters if made by utilizing maleic acid, can be 
isomerized with various conventional amines such as morpholine or 
piperidine to produce the fumarate isomer, as taught in U.S. Pat. No. 
3,576,909, to Schmidle and Schmucker, which is hereby fully incorporated 
by reference with regard to all aspects thereof. Hydroxyl or carboxyl end 
groups are readily obtained by simply utilizing either an excess of the 
glycol or of the acid. Amine groups are added generally by post-reaction 
with an amine compound such as ethylene diamine, and the like. Such 
aspects are of course well known to the art and to the literature. 
Generally, such polyester A blocks have a significant molecular weight, as 
above 500. A preferred ester of the present invention is 
poly(propylenefumarate). 
The monofunctional terminated unsaturated polyester A block is reacted with 
the B block flexible polymer to yield a block copolymer. If the flexible B 
block is monoterminated, an AB type block copolymer will be formed. If the 
flexible polymer B block is a diterminated functional polymer, an ABA type 
block copolymer will be formed. However, if a difunctional terminated 
polyester A block is utilized with a difunctional terminated flexible B 
block, an ABA type block copolymer is produced along with generally small 
amounts of an A(BA).sub.n type block copolymer where n is 2 to 5. 
Typically, such mixtures contain a majority amount, that is at least 50 
percent and often at least 70, 80, or even 90 percent by weight of the ABA 
block copolymer. 
When the flexible polymer B block is hydroxyl terminated, desirably the 
unsaturated polyester A block contains a monofunctional, or less desirably 
a difunctional, terminal acid end group so that an ester reaction occurs 
and an ester linkage is formed. Similarly, if the flexible polymer B block 
contains a carboxyl terminal group, the unsaturated polyester A block end 
group is desirably a hydroxyl so that an ester linkage can be formed. In 
either situation, a conventional esterification reaction is carried out in 
a manner well known to the art. The net result is the formation of an AB 
or an ABA block polymer and possible small amounts of A(BA).sub.n block 
copolymer having an ester linkage between the blocks. 
If the flexible B block is amine terminated, desirably the polyester A 
block has a monocarboxylic acid functional end group. Such a reaction is 
carried out in a conventional manner and results in an amide linkage. 
Alternatively, if the polyester A block is amine-terminated, a 
diisocyanate can be reacted with a mono- or di- hydroxyl terminated B 
block, so that the reaction product thereof with the amine-terminated A 
block results in a urea linkage. 
Regardless of the type of linkage formed between the "A" block and the "B" 
block, the reaction conditions for forming such linkages are well known to 
the art and to the literature, and result in the formation of a novel 
block copolymer. Such reactions including the conditions thereof, etc., as 
well as the linkage reactions set forth hereinbelow are morely fully 
defined in Advanced Organic Chemistry, Reactions, Mechanisms, and 
Structures, J. March, 2nd Edition, McGraw Hill, New York, N.Y., 1977, 
which is hereby fully incorporated by reference including subsequent 
editions thereof. 
It is to be understood that the A and B type blocks are typically preformed 
polymers which are reacted together and that no in situ polymerization of 
the A block or the B block occurs. In other words, the present invention 
is generally free of in situ polymerization or polymerization of one of 
the blocks on an existing block when the molecular weight of the A block 
is from about 500 or 600 to about 5,000. 
It is also within the scope of the present invention to utilize a polyester 
A segment of very low molecular weight, such as for example from about 100 
to about 500 or 600, wherein the ester segment or A block is merely the in 
situ reaction of a single or a few dicarboxylic anhydride and cyclic oxide 
molecules, such as maleic anhydride and propylene oxide. Preferably, the 
flexible B block is hydroxyl terminated. Such low molecular weight 
polyester A blocks result in a block copolymer having a high ratio or 
amount of the flexible polymer A block. 
To prepare such low molecular weight A segments or blocks, it is 
advantageous to react the hydroxy terminated flexible B segment directly 
with the cyclic anhydride and propylene oxide. Suitable catalysts for the 
reaction include the double metal cyanide complex catalysts described 
above as well as the various titanates and alkyl substituted tin compounds 
like dibutyltin oxide. Preferred anhydrides for making such low molecular 
weight A segments have unsaturation such as maleic, tetrahydrophthalic, 
itaconic, nadic, methyl nadic and the like, although mixtures of 
unsaturated and saturated cyclic anhydrides may also be used. Generally, 
any cyclic oxide can be used with ethylene and propylene oxides being 
preferred. 
According to the preferred embodiment of the present invention, the 
flexible polymer B block is hydroxyl terminated and is reacted with a 
monohydroxyl terminated unsaturated polyester A block through the 
utilization of a polyisocyanate to yield a block copolymer having a 
minimum weight of 500 or 600. That is, a polyisocyanate is reacted with 
the hydroxyl end group of the flexible polymer B block thereby leaving a 
free isocyanate group which is subsequently reacted with the hydroxyl end 
group of the unsaturated polyester A block. Examples of polyisocyanates 
which can be utilized generally have the formula 
EQU R(NCO)hd n 
where n is generally about 2 (i.e. a diisocyanate) although it can be 
slightly higher or lower as when mixtures are utilized. R is an aliphatic 
having from about 2 to about 20 carbon atoms with from about 6 to about 15 
carbon atoms being preferred or an aromatic including an alkyl substituted 
aromatic having from about 6 to about 20 carbon atoms, with from about 6 
to about 15 carbon atoms being preferred, or combinations thereof. 
Examples of suitable diisocyanates include 1,6-diisocyanato hexane, 
2,2,4-and/or 2,4,4-trimethyl hexamethylene diisocyanate, p-and 
m-tetramethyl xylene diisocyanate, dicyclohexylmethane-4,4'-diisocyanate 
(hydrogenated MDI), 4,4-methylene diphenyl isocyanate (MDI), p- and 
m-phenylene diisocyanate, 2,4- and/or 2,6-toluene diisocyanate (TDI), 
durene-1,4-diisocyanate, isophorone diisocyanate, (IPDI) 
isopropylene-bis-(p-phenyl isocyanate) and sulfone-bis-(p-phenyl 
isocyanate). Also useful are diisocyanates prepared by capping low 
molecular weight, that is less than 300, diols, ester diols or diamines 
with diisocyanates, such as the reaction products of one mole of 
1,4-butanediol or bis-(4-hydroxylbutyl)-succinate (molecular weight=262) 
with two moles of hexamethylene diisocyanate. TDI and IPDI are preferred 
for reasons set forth herein below. The reaction between the diisocyanate 
and the hydroxyl terminated flexible polymeric B block is carried out in 
an inert atmosphere such as nitrogen, at ambient temperatures and up to 
30.degree. C., desirably in the presence of urethane catalysts. Such 
catalysts are known to the art as well as to the literature and generally 
include tin compounds such as various stannous carboxylates, for example 
stannous acetate, stannous octoate, stannous laurate, stannous oleate and 
the like; or dialkyl tin salts of carboxylic acids such as dibutyltin 
diacetate, dibutyltin dilaurate, dibutyltin maleate, dibutyltin 
di-2-ethylhexoate, dilauryltin diacetate, dioctyltin diacetate and the 
like. Similarly, there can be used a trialkyltin hydroxide, dialkyltin 
oxide or dialkyltin chloride. As an alternative or in addition to the 
above tin compounds, various tertiary amines can be used such as 
triethylamine, benzyldimethylamine, triethylenediamine and 
tetramethylbutanediamine. The tin catalysts, when utilized, are generally 
used in amounts of 0.5 parts or less, i.e., in the range of about 0.01 to 
0.5 parts, by weight per 100 parts of prepolymer. The tertiary amine 
catalysts, when utilized, can be used in amounts of 0.01 to about 5 parts 
by weight per 100 parts of prepolymer. 
It is an important aspect of the present invention that the reaction of the 
diisocyanate with mono- or di- hydroxyl terminated flexible polymer B 
block occurs separately, that is, not in the presence of, in the absence 
of, or free from the mono- or di-hydroxyl functional unsaturated polyester 
A block. This ensures that a random copolymer containing block segments 
therein is not produced. Moreover, it is another important aspect of the 
present invention to utilize diisocyanate compounds which have 
differential reaction rates with regard to the two isocyanate end groups. 
This is to ensure that only one of the groups reacts with the hydroxyl 
terminated flexible B block and the remaining unit generally remains 
unreacted until subsequent reaction of the monohydroxyl terminated 
polyester A block. For this reason, TDI and IPDI are preferred. The amount 
of the diisocyanate utilized is generally an equivalent amount to the 
hydroxyl groups in the flexible B block and thus is an equivalent ratio of 
from about 0.8 to about 1.2, and desirably from about 0.9 to about 1.1. 
Similarly, the amount of the polyester block A is generally an equivalent 
amount to the urethane linkages of the flexible B block, be it one linkage 
or two linkages per B block. 
The mono- or di- hydroxyl terminated unsaturated polyester A block is then 
subsequently added to the vessel or solution containing the urethane 
terminated flexible polymer B block and reacted therewith in a 
conventional manner well known to the art and to the literature. The 
result is a urethane linkage between the polyester A block and the 
flexible polymer B block. 
A distinct advantage of utilizing the urethane reaction route is that a low 
temperature reaction can be carried out which minimizes side reactions and 
that no unreacted compounds remain which have to be removed from the 
reaction product. 
Another method of making a mixture of block copolymers containing a large 
amount of AB block copolymer is to react a diisocyanate-terminated 
flexible polymer B block having two free NCO groups thereon with an 
approximately equivalent amount of a low molecular weight alcohol and then 
subsequently reacting the product with an approximately equivalent amount 
of the functional terminated unsaturated polyester A block. The low 
molecular weight alcohol can be methanol, ethanol, n-propanol, 
isopropanol, t-butanol, and the like. In lieu of the low molecular weight 
saturated alcohol, a functional compound containing an ethylenically 
unsaturated polymerizable group can be utilized, such as hydroxy-styrene, 
hydroxy-ethyl-acrylate, methacrylate, or allyl alcohol. 
Another preferred embodiment relates to the preparation of the low 
molecular weight A blocks which involves the reaction of hydroxyl 
terminated B blocks with a cyclic unsaturated anhydride and an alkalene 
oxide as noted above. Mixtures of saturated and unsaturated anhydrides can 
also be used. 
Another aspect of the present invention is that the above-noted AB, or ABA, 
or A(BA).sub.n block copolymers can be cured. Curing can occur utilizing 
conventional compounds such as ethylenically unsaturated compounds, for 
example vinyl or allyl compounds, and conventional free radical catalyst. 
Examples of ethylenically unsaturated compounds include styrene, a 
preferred compound, vinyl toluene, divinyl benzene, diallyl phthalate, and 
the like; acrylic acid esters and methacrylic acid esters wherein the 
ester portion is an alkyl having from i to 10 carbon atoms such as 
methylacrylate, ethylacrylate, n-butylacrylate, 2-ethylhexylacrylate, 
methyl methacrylate, ethylene glycol dimethacrylate, and the like. Other 
unsaturated monomers include vinyl acetate, diallyl maleate, diallyl 
fumarate, vinyl propionate, triallylcyanurate, and the like, as well as 
mixtures thereof. The amount of such compounds based upon 100 parts by 
weight of the block copolymers can generally vary from about 1 to about 
500 parts by weight, and desirably from about 1 to about 100 parts by 
weight. The free radical initiators can include organic peroxides and 
hydroperoxides such as benzoyl peroxide, dicumyl peroxide, cumene 
hydroperoxide, paramenthane hydroperoxide, and the like, used alone or 
with redox systems; diazo compounds such as azobisisobutyronitrile, and 
the like; persulfate salts such as sodium, potassium, and ammonium 
persulfate, used alone or with redox systems; and the use of ultraviolet 
light with photo-sensitive agents such as benzophenone, 
triphenylphosphine, organic diazos, and the like.

The invention will be understood by reference to the following examples 
setting forth the preparation of unsaturated polyester-blocked flexible 
polymer compositions. 
EXAMPLE 1 
Poly(propylene fumarate)-b-poly(butadiene)-b-poly(propylene fumarate) 
triblock 
In a 1-L resin kettle equipped with thermometer, heating mantle and 
stirring were charged 203 g (70 mmoles --OH) of BFG Hycar 2,000.times.169 
(a dihydroxy-terminated polybutadiene), 263g of styrene, 15.7 g (141mmoles 
total --NCO) of isophorone diisocyanate, 2.3 g of zinc stearate, and 1.4 g 
of DABCO T9 catalyst. The materials were mixed thoroughly under nitrogen 
and warmed to 70.degree. C. After two hours 80 g (70 mmoles --OH) of a 80 
percent solids in styrene solution of a mono-hydroxy unsaturated polyester 
(polypropylene fumarate, 850 MW) was added to the reaction mixture, along 
with 2.5 g of 10 percent benzoquinone in diallyl phthalate, and 0.5 g of 
DABCO T9 catalyst. The reaction mixture was cooled after three hours to 
room temperature, and the solution poured into a suitable container. The 
triblock had a flexible polymer to unsaturated polyester weight ratio of 
3.2 to 1.0, and contained 50 percent solids in styrene. 
EXAMPLE 2 
Poly(propylene fumarate)-b-poly(butadiene-CO-acrylonitrite)-polypropylene 
fumarate) triblock 
The above triblock was prepared by charging a 2-L resin kettle as above 
with 600 g (370 mmoles --OH) of Hycar 1300.times.34 (a 
dihydroxy-terminated poly(butadiene-CO-acrylonitrile, 26 percent AN 
content) and 480 g of styrene which was stirred overnight under nitrogen 
to dissolve. To the stirred solution was then added 52 g (600 mmoles total 
--NCO) of toluene diisocyanate, and 2.0 g DABCO T12 catalyst. The mixture 
was stirred for one-half hour during which time the temperature rose to 
37.degree. C., followed by the addition of 675 g (350 mmoles --OH) of an 
80 percent solids in styrene solution of a mono-hydroxy unsaturated 
polyester (polypropylene fumarate, approx. 1600 MW). The mixture was kept 
at 37.degree. C. with stirring for six hours, and then poured into a 
container. The triblock had a flexible polymer to unsaturated polyester 
weight ratio of 1.1 to 1.0, and contained 65 percent solids in styrene. 
EXAMPLE 3 
Poly(propylene fumarate)-b-poly(butadiene) block co-polymer 
The above block copolymer was prepared by charging 200 g (70 mmoles -OH) of 
Hycar 2,000.times.169 to a 1-L resin kettle along with 234 g of styrene, 
12.5 g (113 mmoles total --NCO) isophorone diisocyanate, 2.0 g of zinc 
stearate, and 2.0 g DABCO T9 catalyst. The starting materials were mixed 
thoroughly under nitrogen, and then heated to 70.degree. C. After 90 
minutes, 1.7 g (28 mmoles --OH) of n-propanol was added, and after 2.5 
hours 36 g (32 mmoles) of an 80 percent solids in styrene solution of a 
monohydroxy unsaturated polyester (polypropylene fumarate, approx. 1400 
MW). The mixture was stirred for another three hours, then cooled and 
transferred to a suitable container. The block copolymer had a flexible 
polymer to unsaturated polyester weight ratio of 7.0 to 1.0, and contained 
53 percent solids in styrene. This composition was a mixture containing 
large amounts of an AB block copolymer. 
EXAMPLE 4 
Poly(propylene fumarate)-b-poly(butadiene-CO-acrylonitrile) block copolymer 
The above block copolymer was prepared in a 1-L resin kettle as above with 
a charge of 361 g (225 mmoles --OH) Hycar 1300.times.34 and 175 g (210 
mmoles total --OH) of 80 percent solids in styrene solution of dihydroxy 
unsaturated polyester (polypropylene fumarate, approximately 1400 MW), 
which were mixed thoroughly at 110.degree. C. under vacuum for 90 minutes. 
The blend was cooled to 80.degree. C. under nitrogen, and 21.6 g (250 
mmoles total NCO) of TDI added followed by stirring for ten minutes. DABCO 
T-12 catalyst (0.8 g) was added, causing an immediate increase in 
viscosity. Stirring was continued for one hour and the mixture cooled to 
50.degree. C. followed by the addition of 531 g of styrene. The solution 
was transferred to a suitable container. The flexible polymer to 
unsaturated polyester weight ratio of this additive was 2.6 to 1.0, and 
the solution contained 48 percent solids in styrene. This composition was 
a mixture containing A(BA).sub.n block copolymers. 
EXAMPLE 5 
Polypropylene fumarate)-b-poly(butadiene-co-acrylonitrile) block copolymer 
The above block copolymer was prepared by charging a 500-ml resin kettle 
with 189 g of a solution of Hycar 1300.times.31 (dicarboxy terminated 
polybutadiene-co-acrylonitrile, 10 percent AN content; 48.5 weight 
percent, 91.5 g, 51 mmoles carboxyl) and dihydroxy terminated 
polypropylene fumarate (1300 MW; 51.5 percent, 97.5 g, 150 mmoles --OH). 
The kettle was heated under vacuum at 150.degree. to 160.degree. C. for 
two hours to remove water. The product was transferred to a suitable 
container. The block copolymer had a flexible polymer to unsaturated 
polyester weight ratio of 0.9 to 1.0. This composition contained ABA block 
copolymers. 
EXAMPLE 6 
Poly(propylene fumarate)-b-poly(butadiene-co-acrylonitrile) block copolymer 
The above block copolymer was prepared by charging a 1.5-L resin kettle 
with 508 g (726 mmoles --OH) of unsaturated polyester (dihydroxy 
terminated polypropylene fumarate, approximately 1400 MW) 404 g (234 
mmoles carboxyl of Hycar 1300.times.13 (dicarboxy terminated 
Polybutadiene-co-acrylonitrile, 26 percent AN content), 0.4 g 
benzoquinone, and 0.4 g of triphenylphosphonium bromide. The mixture was 
stirred and heated to 150.degree. C. under vacuum for four hours. After 
cooling to room temperature, 508 g of styrene was added and mixed to 
dissolve the polymer. The product was transferred to a suitable container. 
The block copolymer had a flexible polymer to unsaturated polyester ratio 
of 0.8 to 1.0, and contained 57 percent solids in styrene. This 
composition contained ABA block copolymers. 
EXAMPLE 7 
Poly(propylene fumarate)-b-poly(tetrahydrofuran)-b-poly(propylene fumarate) 
triblock 
The above triblock was prepared by combining 400 grams of 
isocyanate-terminated poly(tetrahydrofuran 347 mmoles NCO), available from 
Air Products under the trademark PET90A, 312 grams of toluene, 3 grams of 
DABCO T9.RTM. catalyst, available from Air Products and Chemical Inc., and 
224 grams of a solution of monohydroxy-terminated poly(propylene fumarate) 
(80 percent solids in stytens, 347 mmoles total --OH) in a one liter resin 
kettle equipped with nitrogen purge, a heating mantle, and a stirrer. The 
reagents were thoroughly mixed at room temperature under nitrogen, after 
which the contents were heated and maintained at 40.degree. C. until the 
reaction was complete. The progress of the reaction was monitored using 
FTIR. Completion of the reaction was marked by the disappearance of the 
--NCO absorbance from the IR spectrum, at which time the product was 
cooled to room temperature. This triblock copolymer had a flexible polymer 
to unsaturated polyester ratio of approximately 2 to 1. 
EXAMPLE 8 
A poly(propylene fumarate)-b-poly(butadiene)-b-poly(propylene fumarate) 
triblock 
The above triblock was prepared by combining, in a one liter resin kettle 
equipped with nitrogen purge, heating mantle, and stirrer, 500 grams of 
hydroxy-terminated polybutadiene (137 mmoles total OH), available from the 
BFGoodrich Chemical Company under the trademark HYCAR 
2,000.times.169.RTM., 310 grams of toluene, grams of isophorone 
diisocyanate having 279 mmoles total --NCO, and 3 grams of DABCO 
T9.RTM.catalyst. The contents were thoroughly mixed under nitrogen, and 
then warmed to 60.degree. C. for 2.5 hours. To the kettle were added 93 
grams of a solution of monohydroxy-terminated poly(propylene fumarate) (80 
percent solids in styrene, 144 mmoles total --OH), and 150 grams of 
toluene to reduce the viscosity. The contents were reacted for about 3 
hours at 60.degree. C. until the IR spectrum indicated complete 
consumption of --NCO. The product was then cooled to room temperature. 
This triblock copolymer had a flexible polymer to unsaturated polyester 
ratio of 6.2 to 1.0. 
EXAMPLE 9 
Hydroxypropylmaleate-b-poly(diethyleneadipate)-b-hydroxypropylmaleate 
triblock 
A 1-quart polymerization bottle was charged with 156.5 g (313 mmoles --OH) 
of Formrez 11-112 (a dihydroxy poly(diethylene adipate), available from 
Witco Chemical Co.), 30.7 g of maleic anhydride (313 mmoles), 124 g of 
toluene as solvent, and 0.3 g of tetrabutyl titanate catalyst. The bottle 
was sealed and heated in a waterbath to 80.degree. C. On completion of the 
reaction of the maleic anhydride as determined by FTIR, 19.1 g of 
propylene oxide (329 mmoles) was charged to the bottle, and the reaction 
completed at 65.degree. C. Determination of acid number and NMR indicated 
100 percent maleic anhydride capping, and approximately 80 percent 
hydroxypropyl ester formation. This triblock copolymer had a flexible 
polymer to unsaturated polyester ratio of approximately 3.1 to 1. 
EXAMPLES 10 
Hydroxpropylmaleate-b-Poly(propylene adipate)-b-hydroxypropylmaleate 
triblock 
A 1-quart polymerization bottle was charged with 407.3 g (1.63 mmoles --OH) 
of Formrez 33-225 (a dihydroxy poly(propylene adipate), available from 
Witco Chemical Co.), 160.1 g maleic anhydride (1.63 mmoles), 153 g toluene 
as solvent, and 1.7 g of tetrabutyl titanate catalyst. The bottle was 
sealed and heated in a water-bath to 80.degree. C. On completion of the 
reaction of the maleic anhydride as determined by FTIR, 94.7 g of 
propylene oxide (1.63 mmoles) was charged to the bottle, and the reaction 
completed at 65.degree. C. Determination of acid number and NMR indicated 
100 percent maleic anhydride capping, and approximately 80 percent 
hydroxypropyl ester formation. This triblock copolymer had a flexible 
polymer to unsaturated polyester ratio of approximately 1.6 to 1. 
The above-identified diblock and triblock, etc., polyester-flexible polymer 
copolymers can be utilized as toughening agents in a variety of plastics 
such as unsaturated polyesters or vinyl ester resins. Moreover, they can 
be directly applied to a fiber structure and cured to coat the same and 
alleviate stress cracking on the surface of the fibers. Subsequently, the 
fiber structure coated with the cured polyester-flexible polymer block 
copolymers of the present invention can be utilized in various matrix 
formations such as in sheet molding compounds, in the preparation of sheet 
resins containing fiber reinforcement therein, in the preparation of fiber 
structures utilized in mats, nonwovens, wovens, and the like, in wet 
lay-up sheets, in resins utilized in injection molding, bulk molding, and 
the like. 
While in accordance with the Patent Statutes, the best mode and preferred 
embodiment has been set forth, the scope of the invention is not limited 
thereto, but rather by the scope of the attached claims.