Reactive modifier of elastomeric comb copolymer for thermosetting resins and process for making the same

A reactive polymeric modifier to improve toughness and/or flexibility of thermosetting resins where the polymer has a comb configuration including a saturated polymeric backbone having reactive groups at each end and at least one pendent chain which is miscible with the thermosetting resin while it is uncured; the backbone being a polymeric chain of carbon-carbon linkages free of olefinic unsaturation, having a glass transition temperature Tg in the range from -100.degree. C. to 25.degree. C.; the reactive groups being reactive with the thermosetting resin, being positioned on both ends of the backbone, and comprising, on average, at least 1.2 but less than 2 reactive groups positioned so as to yield a substantially difunctionalized comb; the pendent chain or chains being linked to said backbone, being present in an amount in the range from 3% to 40% by weight of said comb copolymer, and having from 2 to 250 repeating units selected from the group consisting of polyester, polyether, polystyrene, and polymethacrylate; and, the comb polymer having a number average molecular weight in the range from 1,000 to 20,000, and a process for making the modifier.

This invention relates to a comb copolymer having a saturated polymeric 
backbone with carbon-carbon (C-C) linkages and pendent chains which 
provide miscibility in a thermosetting resin, for example, polyester such 
as polycaprolactone, or a polyether, such as polyepichlorohydrin; and, the 
backbone has terminal functional groups, for example carboxyl-functional 
groups, as a result of a free-radical polymerization with, for example, 
4,4'-azobis-4-cyanovaleric acid (also commonly referred to as 
azodicyanovaleric acid) or ADVA. The term a polymeric backbone with 
carbon-carbon (C-C) linkages or a C-C backbone, means a backbone of a 
polymer with repeating units containing no atom other than carbon atom in 
the backbone linkages. 
The comb copolymer is used as a reactive modifier to improve the toughness 
or flexibility of a thermosetting resin (hereafter "thermoset" for 
brevity). By the term "reactive modifier" we refer to a relatively low 
molecular weight ("mol wt") elastomeric polymer which possesses terminal 
functional groups reactive with the uncured target thermoset and functions 
either as a toughening agent or toughener ("TA"), and/or, a flexibilizing 
agent or flexibilizer ("FA"). By "toughened" it is meant that the area 
under the stress-strain curve and the fracture energy are significantly 
increased without substantially decreasing the glass transition 
temperature (Tg), the modulus, or diminishing other desirable mechanical 
properties of the material; stated differently, upon being toughened, a 
material which is inherently brittle has the ability to absorb more energy 
without rupture than it could before it was toughened. It is known that 
TAs found to be effective in a thermoplastic substrate do not exhibit the 
same effect in a thermoset. Quantitatively, a material is "flexibilized" 
when the area under the stress-strain curve is increased, but with both, 
loss of modulus, and decrease in Tg, and likely, also other mechanical 
properties. 
It is known that desirable toughness in a thermoset is most preferably 
imparted by an elastomeric modifier, which, (1) has reactive functional 
groups, (2) is miscible in the thermoset before curing, and (3) 
precipitates and forms a uniformly distributed elastomeric microphase in 
the thermoset matrix as the molecular weight of the thermoset increases. 
The microphase desirably has small particle size, generally smaller than 
25 .mu.m, and high interfacial bond strength between the microphase and 
the matrix. The size and size distribution of elastomeric microparticles 
are partially dependent on the curing kinetics--the cure schedule, type 
and reactivity of the curing agent, and cure chemistry involved. The most 
influential factor is the miscibility between the thermoset and the 
reactive modifier. Since the miscibility not only affects the size and 
size distribution of the microphase of the elastomer but also the 
interfacial bond strength between the matrix and the microparticles. If 
miscibility is too good, microphase separation will not occur. It will 
causes severe plasticization and the reactive modifier functions as a 
flexibilizer. On the other hand, if miscibility is poor, it causes 
macroscopic demixing of the elastomer modifier before curing or the 
formation of undesirable macrophase separation such as in the systems of 
epoxy resins with carboxyl-terminated polybutadiene or carboxyl-terminated 
polyacrylates. 
To meet the foregoing, it is desirable that the TA or FA be substantially 
difunctionalized so that at least one, and preferably both ends of each 
additive molecule are reacted with a thermoset upon curing. It is 
generally believed that difunctionality of these reactive elastomers is 
essential to achieve desirable toughening. This thinking is typified by 
U.S. Pat. Nos. 3,285,949 and 3,823,107, and the articles "Toughening of 
Epoxy Resin by an Elastomeric Second Phase" by F. J. McGarry and A. M. 
Willner, in Massachusetts Institute of Technology, R68-8, March, 1968 and 
"The Chemistry of Rubber Toughened Epoxy Resin I." by A. R. Siebert and C. 
K. Riew in 161th ACS National Meeting, Org. Coating Div., March, 1971. The 
term "substantially difunctionalized" is used to acknowledge that, from a 
practical viewpoint, one cannot make, on average, a theoretically fully 
difunctional polymer by a free-radical polymerization. Therefore the term 
"substantially difunctionalized" is used to refer to a molecule which has 
at least 1.2, but, on average less than 2 terminal functional groups at or 
near the ends of a molecule. 
CTBN polymers (Carboxyl-terminated copolymers of butadiene and 
acrylonitrile) are the most widely used reactive modifier for thermosets 
and commercialized under a trade name of Hycar.RTM. reactive polymers by 
B.F. Goodrich Co. CTBN polymers are produced by a free radical solution 
polymerization using a functional azo initiator, such as ADVA 
[4,4'-azobis(4-cyano-pentanoic acid)], as disclosed by Siebert in U.S. 
Pat. No. 3,285,949. The CTBN polymers are `fixed` in the matrix of 
thermosetting resins upon curing because the terminal carboxyl (COOH) 
groups of the copolymers are reactive with the functional groups of the 
thermosetting resin, such as the oxirane end groups of an epoxy resin, 
diglycidyl ether of bisphenol A ("DGEBA"). In these linear straight-chain 
configurations, the immiscible butadiene homopolymer is modified by 
incorporating polar acrylonitrile to provide desirable miscibility of the 
reactive modifier with the target thermoset and enable the formation of 
the favorable microphase morphology in the cured thermoset to provide 
toughness. 
However, CTBN polymers are known to be inherently susceptible to 
ultra-violet light and thermo-oxidative degradation due to the presence of 
double bonds of the butadiene repeating units. CTA polymers 
(Carboxyl-terminated acrylate polymers), which are free of olefinic 
unsaturation, made in a manner analogous to CTBN polymers as disclosed by 
McCarthy in U.S. Pat. No. 3,465,058, are the ideal choice. But CTA 
polymers are not optimumized tougheners. The acrylate polymer has 
extremely poor miscibility with nearly all thermosetting resins and is not 
able to form favorable microphase morphology upon curing to provide 
toughness. 
Attempts have been made to improve the miscibility of reactive acrylic 
polymers as exemplified by the publication "An Alternative Liquid Rubber 
for Epoxy Resin Toughening--Improving Poly(n-butyl acrylate) Rubber-Epoxy 
Compatibility by Using of Acrylonitrile and Acrylic Acid Copolymers and 
Terpolymers", Kirshenbaum et al., in Adv. in Chem. Series 208: 
Rubber-Modified Thermoset Resins, C. K. Riew ed., Ch 11, p. 163, 1984. The 
studies have found that the miscibility of acrylic polymer with epoxy 
resin (Epon 828) is significantly improved by incorporation of a polar 
monomer, such as acrylonitrile or acrylic acid. However, the impact 
strength improvement is insignificant at best. Consequently, a reactive 
polymer having miscibility with a thermoset may not perform as an 
effective toughener. 
European patent applications 87202352.8 and 87200021.1 to Muramoto et al, 
published as 0,269,187 A2 and 0,231,038 disclose comb copolymers having no 
terminal functional groups at opposite ends of their saturated 
carbon-carbon backbones, but the pendent chains have reactive functional 
groups. Muramoto et al then copolymerized the macromer with a monomer 
having .alpha.,.beta. unsaturation using (based upon the examples) less 
than 1 part by weight or 0.4 part by mole of ADVA neutralized with an 
alkali in deionized water to effect the emulsion polymerization of methyl 
methacrylate (MMA) and n-butyl acrylate (nBA) see example 15, of the '187 
specification. Neutralized ADVA was used only to provide the needed water 
soluble initiator, and to make a conventional MMA-nBA copolymer in a 
conventional emulsion polymerization, using a conventional water soluble 
initiator, except for using no conventional surfactant. 
This invention provides a reactive comb-shaped modifier for a thermoset, 
wherein the pendent chain or chains provides desirable miscibility of the 
modifier in the thermoset. The miscibility and reactive terminal groups of 
the reactive modifier of the present invention provide unexpected 
toughness and/or flexibility to the thermoset being modified. 
SUMMARY OF THE INVENTION 
The present invention has resulted from the discovery of a novel reactive 
polymeric modifier to improve toughness and/or flexibility of a 
thermosetting resin possessing substantially difunctionalized reactive 
groups at both ends of the toughening polymer chain and having a 
comb-shaped or "comb" structure having a backbone of an elastomeric 
acrylic chain and a pendent chain or chains which are miscible with 
thermosetting resin to be modified. Particularly useful are pendent 
chain(s) having repeating units in the range from 2 to 500 and being 
present in the range from 3% to 40% by weight of said comb-shaped 
copolymer. The choice of an appropriate repeating unit of the pendent 
chain, ensures that the modifier is miscible with the thermosetting resin 
before curing, to function as an effective toughener and/or flexibilizer. 
The terminal functional groups of the modifier are reactive with the 
uncured thermosetting resin, and could be carboxyl, hydroxyl, amino, 
epoxy, vinyl or thio. The present invention provides a reactive comb 
having a predominant backbone of polyacrylate having at least 1.2 but less 
than 2 functional groups at the ends of the backbone. 
The fact that the backbone of the elastomeric acrylic chain is free of 
olefinic unsaturation means that the reactive modifier is highly resistant 
to ultraviolet light and thermo-oxidative degradation. 
It has been further discovered that the elastomeric, telechelic, reactive 
comb-shaped ("comb") copolymer having a desirably low numerical average 
molecular weight (Mn) in the range from 1,000 to 20,000, a backbone 
containing enough elastomeric monomer or "E-monomer" to imbue the backbone 
with elastomeric properties, and pendent chains derived from a suitable 
macromer, can be reproducibly produced in a free radical polymerization 
using a difunctional initiator which contributes its functional groups to 
the terminal ends of the backbone, as it forms. The result is the direct 
formation of the reactive comb with terminal carboxyl or hydroxyl end 
groups, although these can readily be converted to epoxy, amino, vinyl and 
thio end groups. 
The comb can be made in excellent yields in a process comprising reacting 
an .alpha.,.beta.-unsaturated macromonomer with at least one ethylenically 
unsaturated monomer, in a non-aqueous solvent, in the presence of an 
initiator which generates necessary free radicals, and is present in an 
amount at least sufficient to introduce desired reactive groups at the 
terminal ends of the backbone. Such a comb, if free from olefinic 
unsaturation in either its backbone or its pendent chains, is highly 
stable to degradation by actinic radiation, such as is experienced 
outdoors, in bright sunlight. It is also highly resistant to 
thermal-oxidative degradation and can be used in applications at higher 
service temperatures. In those instances where such degradations are not a 
consideration, it may be desirable to use a backbone containing some or 
all monomers, in each repeating unit of which at last some unsaturation 
remains. 
The modifiers of this invention can provide a reactive comb for use as a 
toughener and/or a flexibilizer reactive with one or more uncured 
thermosetting resins, such as acrylic resin, polyester resin, polyurethane 
resin, epoxy resin, vinyl ester resin, and unsaturated polyester resin, 
the reactive comb having miscibility with the uncured thermosetting resin 
because of the presence of the pendant chain or chains evidenced by the 
formation of a single phase with the uncured resin at a temperature in the 
range from 20.degree. C. to 200.degree. C., and homogeneously distributed 
therein. When the resin starts to be cured and build up its molecular 
weight, the reacted comb would be precipitated out prior to gelation. The 
elastomeric comb is precipitated as the disperse microphase in a 
continuous phase of the cured resin matrix, and the reacted comb is 
substantially homogeneously distributed throughout the matrix resin to 
provide toughness. On the other hand, when the reactive comb is served as 
a flexibilizer, no precipitation of the reacted comb or formation of a 
microphase is occurred. 
An alternative method for making the comb copolymer comprises starting a 
free radical copolymerization of "E-monomer" and a difunctional monomer or 
"D-monomer", optionally in combination with a third rigid monomer or 
"R-monomer", with a difunctional initiator to provide terminal reactive 
groups for the copolymer. The copolymer has an elastomeric backbone of 
acrylic chain possessing reactive functional groups at both end derived 
from the initiator and pendent reactive functional groups randomly 
distributed along the backbone from "D-monomer". The comb copolymer is 
subsequently made by coupling the pendent reactive groups of "D-monomer" 
with a mono- or difunctional oligomer having repeating units which are 
miscible with the targeted thermosetting resin. The oligomer is selected 
from the group of polyester, polystyrene, polyether or polymethacrylate. 
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The reactive polymeric modifier of the present invention possessing 
reactive functional groups at both ends of the toughening polymer chain 
and a comb-shaped or "comb" structure having a backbone of an elastomeric 
hydrocarbon chain and pendent chains which are miscible with the 
thermosetting resin to be modified. The reactive modifier has a number 
average molecular weight (Mn) in the range from 1,000 to 20,000, 
preferably in the range from 1,500 to 10,000, most preferably in the range 
from 2,500 to 6,000, and on average, at least 1.2 but less than 2.0 
reactive functional groups positioned at said backbone's ends. The 
functional groups at both ends of the polymer chain in the said reactive 
modifier are reactive with the functional groups of the uncured 
thermosetting resin and selected from group consisting of carboxyl, 
hydroxyl, amino, epoxy, vinyl, and thio group. The elastomeric 
carbon-carbon backbone linkages of the said reactive modifier has a glass 
transition temperature Tg in the range from -100.degree. C. to 25.degree. 
C. and is derived from free radical polymerization of one or more 
ethylenically unsaturated monomers, preferably free of olefinic 
unsaturation, most preferably acrylic homopolymers or copolymers. 
Particularly useful is the pendent chain or chains of the said reactive 
modifier having repeating units in the range from 2 to 250, preferably in 
the range from 2 to 100, most preferably in the rang from 3 to 25 and 
being present in the range from 3% to 40% by weight of said comb-shaped 
copolymer, preferably in the range from 5% to 25% by weight, and being 
selected from the group consisting of polyester, polyether, polystyrene, 
and polymethacrylate. The appropriate choice of repeating unit of the 
pendent chain, ensures that the modifier is miscible with the 
thermosetting resin before curing and functions as an effective toughener 
and/or flexibilizer. 
The elastomeric, telechelic, reactive comb-shaped ("comb") copolymer of 
this invention can be produced in a free radical polymerization, 
comprising, copolymerizing at least one .alpha.,.beta.-unsaturated monomer 
in the range from 97% to 60% by weight, preferable in the range from 95% 
to 75% by weight, with a macromer of polyester, polyether, polystyrene or 
polymethacrylate possessing a free radical polymerizable acrylic, allylic 
or styrylic head group, which may be grouped individually or in 
combination, in the range from 3% to 40% by weight, preferable in the 
range from 95% to 75% by weight, having repeating units in the range from 
2 to about 250, preferably 2 to 100, in a substantially nonaqueous 
solvent, in the presence of in the range from 2 to 25 moles of a 
difunctional initiator per 100 moles of monomers used, at a temperature in 
the range from 10.degree. C. to about 150.degree. C., depending upon the 
half-life of the initiator used. By "substantially non-aqueous" is meant 
that less than 10 parts of water are present per 100 parts of diluent 
mass. The initiator contributes its functional groups to the terminal ends 
of the backbone of the comb copolymer, as it forms. The result is the 
direct formation of the reactive comb with terminal carboxyl, hydroxyl, 
epoxy, and thio end groups derived from the initiator with a corresponding 
functional group. Each of the foregoing groups may be introduced, with 
varying degrees of success, by either an azo compound or an organic 
peroxide. It may be desirable, in some cases, that the reactive terminal 
carboxyl or hydroxyl groups of the comb copolymer are obtained by 
hydrolyzing the terminal functional groups of the resulting copolymer made 
with an initiator having easily hydrolyzable alkyl ester or 
trialkylsilyoxy groups, respectively. The resulting reactive comb-shaped 
modifier has the following structure: 
EQU R.sup.e --X--Q--X--R.sup.e (I) 
wherein, "R.sup.e --X--" is either directly derived from the difunctional 
initiator, preferably an azo compound or an organic peroxide, or obtained 
by hydrolyzing the group directly derived from the difunctional initiator 
having easily hydrolyzable alkyl ester or trialkysilyloxy group after the 
comb copolymer is made, Re is a reactive functional group which can be 
carboxyl, hydroxyl, epoxy, or thio groups, although these could be 
converted to amino or vinyl as will be described hereinafter, X is a 
residual group which depends upon the initiator employed and Q represents 
the comb-shaped copolymer without its terminal functional groups having 
the backbone with pendent chains of the following structure: 
##STR1## 
wherein [M.sub.o ].sub.n, represents the elastomeric carbon-carbon 
backbone component of the comb-shaped copolymer derived from free radical 
polymerization of one or more ethylenically unsaturated monomers 
represented by Mo, [M.sub.o ] represents the repeating unit of one or more 
ethylenically unsaturated monomers, and the backbone comprising linked 
repeating units of at least (i) one E-monomer, and optionally (ii) either 
a R-monomer, or (iii) a D-monomer, or both; (i), (ii) and (iii) together, 
and consisting essentially of (i) from 70%-100% by wt of the backbone, of 
at least one E-monomer in combination with (ii) from 0-30% by wt of a 
R-monomer, and, (iii) 0-10% by wt of a difunctional monomer having 
.alpha.,.beta.-olefinical unsaturation; 
##STR2## 
represents the repeating units of the graft component of the comb-shaped 
copolymer derived from free radical polymerization of a macromer of 
polylactone, polyether, polystyrene, or polymethacrylate, said the 
macromer is represented by the general structure: 
EQU R--[M].sub.m --Z (LM) 
wherein R represents a mono-olefinically unsaturated group selected from 
the following: 
(A) an acrylic or methacrylic group wherein the ethylenically unsaturation 
is adjacent to a carbonyl group, 
(B) a styrylically unsaturated group wherein the ethylenical unsaturation 
is adjacent to an aromatic ring, and, 
(C) an allylically unsaturated group; 
[M] represents repeating unit of a polylactone, polyether, polystyrene, or 
polymethacrylate, 
m represents an integer in the range from 2 to about 250, preferably in the 
range from 2 to 100, most preferably in the rang from 3 to 25; polyether, 
polystyrene, or polymethacrylate, 
m represents an integer in the range from 2 to about 250, preferably in the 
range from 2 to 100, most preferably in the rang from 3 to 25; 
Z is a terminal group selected from the group consisting of --OR.sup.1, 
--OOCR.sup.1, --NHOCR.sup.1, --OOCR.sup.2 COOH, --OSiR.sub.3.sup.1, 
--OCH.sub.2 CH.sub.2 CN, --OSO.sub.3 Na, --OSO.sub.3 K, --OSO.sub.3 Li, 
--OSO.sub.3 NH.sub.4, --OSO.sub.3 H, --R.sup.1, and --H, wherein R.sup.1 
is selected from the group consisting of C.sub.1 -C.sub.20 alkyl, 
alkoxyalkyl, and haloalkyl, and C.sub.6 -C.sub.20 aryl and aralkyl; and, 
R.sup.2 is a divalent C.sub.1 -C.sub.10 aliphatic, alicyclic, or aromatic 
hydrocarbon linkage; 
n' represents an integer in the range from 1 to 30, preferably in the range 
from 1 to 15, most preferably in the rang from 2 to 10 and refers to the 
number of repeating units of a macromer of the graft component; and 
n" represents an integer in the range from 12 to 500, preferably in the 
range from 25 to 250, most preferably in the range from 20 to 150 and 
refers to the number of repeating units of one or more ethylenically 
unsaturated monomers of the backbone component; 
wherein the sum of n'+n' is such that the molecular weight Mn of the 
reactive comb-shaped copolymer is at least 1,000 and no greater than 
20,000, preferably from 1,500 to 10,000, most preferably from 3,000 to 
6,000; and, 
the ratio of n'/n" is chosen to provide the macromer in an amount in the 
range from 3 to 40 wt % of the total comb-shaped copolymer, preferably in 
the range from 5% to 25% by weight. 
The free-radical initiator capable to derive functional groups directly to 
both ends of the comb-shaped copolymer of (I) is a difunctional azo 
compound selected from the group consisting of 
4,4'-azobis-(4-cyano-pentanoic acid), 
4,4'-azobis-(4-cyano-2-methylpentanoic acid), 
2,2'-azobis-(2-cyano-pentanoic acid), 2,2'-azobis-(4-cyano-pentanoic 
acid), 2,2'-azobis-(2-methylpropanic acid), 2,2'-azobis-[2-(hydroxymethyl) 
propionitrile], 
2,2'-azobis-{2-methyl-N-[1,1-bis(hydroxymethyl)]-2-hydroxyethyl] 
propionamide}. The preferable azo initiators are 
4,4'-azobis-(4-cyano-pentanoic acid) (ADVA) and 
2,2'-azobis-[2-(hydroxymethyl) propionitrile]. 
The free-radical initiator capable of providing functional groups after 
hydrolysis is a difunctional azo compound selected from the group 
consisting of dimethyl 4,4'-azobis-(4-cyano-pentanate), diacetate ester of 
2,2'-azobis-(4-methyl-2-pentanol), diacetate ester of 
2,2'-azobis-(2-methyl-2-propanol), dimethyl 
2,2'-azobis-(2-methypropionate), diacetate ester of 
2,2'-azobis-[2-(hydroxymethyl) propionitrile], 
2,2'-azobis-[2-(trimethylsilyloxymethyl) propionitrile], and dimethyl 
2,2'-azobis-(2-methylpropinate)- When 4,4'-azobis-(4-cyano-pentanoic acid) 
or dimethyl 4,4'-azobis-(4-cyanopentanate) (after hydrolysis) is used as 
an initiator, the --X--R.sup.e of the comb (I) is 
##STR3## 
wherein, the reactive terminal functional group R.sup.e is COOH. When 
2,2'-azobis-[2-(hydroxymethyl) propionitrile] or 
2,2'-azobis-[2-(trimethylsilyloxymethyl) propionitrile] (after hydrolysis) 
is used as an initiator, the--X--R.sup.e of the comb (1) is 
##STR4## 
wherein, the reactive terminal functional group Re is OH. 
Another free-radical initiator capable of providing functional groups 
directly to both ends of the comb-shaped copolymer of (I) is a 
difunctional organic peroxide selected from the group consisting of diacyl 
and dialkyl peroxides, peroxydicarbonates, and peroxyketals containing 
functional groups consisting of carboxyl, hydroxyl, epoxy, and thio groups 
at both ends of the molecule. 
Another free-radical initiator capable of providing hydroxyl functional 
groups directly to both ends of the comb-shaped copolymer of (I) is 
hydrogen peroxide. 
The elastomeric backbone of comb copolymer (1) comprises repeating units 
derived from one or more ethylenically unsaturated monomers, Mo, 
representing an E-monomer alone; or in combination, an E-monomer with an 
R-monomer and/or a D-monomer; wherein the E-monomer provides the 
elasticity, is present at 65%-100% by weight of the backbone of the comb 
copolymer, and is consisting of: 
(i) esters of acrylic acid with C.sub.2 -C.sub.18 alcohols including 
alkoxyl and halogen derivatives thereof, such as ethyl acrylate, propyl 
acrylate, butyl acrylate, hexyl acrylate, 2-ethylbutyl acrylate, 
2-ethylhexyl acrylate, dodecyl acrylate, octadecyl acrylate, ethoxyethyl 
acrylate, ethoxypropyl acrylate, ethoxybutyl acrylate, methoxyethyl 
acrylate, methoxypropyl acrylate, methoxybutyl acrylate, 
2-(2-ethoxyethoxy) ethyl acrylate, 2,2'2-trifluoroethyl acrylate; 
(ii) C.sub.2 -C.sub.6 .alpha.-olefins, such as ethylene, propylene, and 
butylene; 
(iii) C.sub.4 -C.sub.5 dienes, such as butadiene, isoprene, and 
chloroprene; 
(iv) vinyl C.sub.1 -C.sub.8 alkyl ethers, such as vinyl ethyl ether, vinyl 
propyl ether, vinyl butyl ether, and vinyl ethylhexyl ether; wherein the 
R-monomer provides rigidity, lower cost and/or compatibility, is present 
at 0%-30% by weight of the backbone of the comb copolymer, and is 
consisting of: 
(i) C.sub.1 -C.sub.4 alkyl methacrylate, such as ethyl methacrylate, propyl 
methacrylate, butyl,methacrylate, and methyl methacrylate; 
(ii) C.sub.8 -C.sub.12 styrene and e-methylstyrene, including halogenated 
derivatives thereof, such as styrene, alpha-methylstyrene, chlorostyrene, 
vinyl toluene; 
(iii) acrylonitrile and methacrylonitrile; and 
(iv) vinyl chloride, vinyl acetate, vinylidene chloride, vinyl pyridine, 
and vinyl pyrrolidone; wherein the D-monomer provides an additional 
reactive functional group to the comb at the pendent positions, is an 
ethylenically unsaturated monomer having an additional functional group 
selected from the group consisting of carboxyl, hydroxyl, epoxy, 
isocyanato, and thio, is present at 0%-10% by weight of the backbone of 
the comb copolymer, and is consisting of: 
(i) hydroxyl containing hydroxy C.sub.2 -C.sub.4 alkyl (meth)acrylate, 
where "(meth)acrylate" indicates either an acrylate or a methacrylate, 
such as 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 
4-hydroxybutyl (meth)acrylate, and 2,3-dihydroxypropyl (meth)acrylate; 
(ii) epoxy containing glycidyl (meth)acrylate and allyl glycidyl ether; 
(iii) thio containing thio C.sub.2 -C.sub.4 alkyl (meth)acrylate, such as 
2-thioethyl (meth)acrylate, thiopropyl (meth)acrylate, 4-thiobutyl 
(meth)acrylate, 2,3-dithiopropyl (meth)acrylate; 
(iv) hydroxyl containing styrene, such as o,p-hydroxystyrene and 
o,p-hydroxystyrene with non-reactive ring substituents; 
(v) isocyanato containing 2-isocyanatoethyl (meth)acrylate; and, 
(vi) acid containing (meth)acrylic acid and its dimer. 
In the preferred embodiment of this invention, the comb is a copolymer of 
the chosen macromer and one or more ethylenical monomers for the backbone 
selected from 
(i) ethyl acrylate, butyl acrylate, ethylhexyl acrylate, and mixture of two 
or all, optionally, with 0-10 wt % of a D-monomer; or, 
(ii) butadiene and mixture of butadiene and acrylonitrile. When a mixture 
of ethyl acrylate, butyl acrylate, and acrylic acid is selected in (i), 
the --[M.sub.o ].sub.n" -- of (II) is consisted of repeating units of 
##STR5## 
randomly distributed, and when a mixture is selected in (ii), the 
--[M.sub.o ].sub.n" -- of (II) is consisted of repeating units of 
##STR6## 
randomly distributed. 
In the best mode, and most preferred embodiment of this invention, the 
backbone is a copolymer of the chosen macromer and ethyl acrylate, butyl 
acrylate, ethylhexyl acrylate, or mixture of two or all for an 
ultra-violet and thermo-oxidative resistant comb. 
The macromer of (LM) is selected from the group of polyester, polyether, 
polystyrene or polymethacrylate. The macromers of polyester are made by 
ring-opening polymerization of at least one lactone as described in U.S. 
Pat. Nos. 4,791,189, 4,983,689, 3,655,631, 4,188,472, 4,368,320, 
4,504,635, and 4,683,287. The disclosures of which are incorporated by 
reference thereto as if fully set forth herein. The preferred chains may 
be of a (i) homopolymer of lactone, (ii) random copolymer of at least one 
lactone, or, (iii) block copolymer of lactone-b-ether, or, of 
ether-b-lactone, provided the comb is made by the afore-described solution 
polymerization process. The lactone is selected from a three to seven 
member-ring cyclic monomer such as epsilon-caprolactone, 
delta-caprolactone, beta-propiolactone, beta-butyrolactone, and 
delta-valerolactone, and most preferably, epsilon-caprolactone. Also 
usable are lactones having equal or more than eight-member ring, such as 
zeta-enantholactone and eta-capryllactone, but they are less favorable. 
The macromers of polyesters are also made by a coupling reaction as 
described in U.S. Pat. Nos 4,281,172, 4,340,497, and 4,632,975. An example 
of a macromer of polycarprolactone made by ring-opening polymerization has 
a structure of 
##STR7## 
wherein m is an integer in the range from 2 to 250. 
The macromers of polyethers are made by ring opening polymerization of at 
least one cyclic ether as described in U.S. Pat. Nos. 4,680,358, 
4,722,978, and Re. 31,468. The disclosures of which are incorporated by 
reference thereto as if fully set forth herein. The preferred chains may 
be of a homopolymer or random or block copolymer of polyether made from 
cyclic ether(s) selected from propylene oxide, butylene oxide, oxetane, 
tetrahydrofuran, epichlorohydrin, epibromohydrin, ethyl glycidyl ether, 
propyl glycidyl ether, butyl glycidyl ether, ethylhexyl glycidyl ether. In 
random or block copolymer, other cyclic ethers may be incorporated in a 
minor amount. The macromers of polyethers may also be made by coupling 
reaction in a manner as described in U.S. Pat. Nos 4,281,172, 4,340,497, 
and 4,632,975. An example of a macromer of polyepichlorohydrin made by 
ring-opening polymerization has a structure of 
##STR8## 
wherein m is an integer in the range from 2 to 250. 
The macromers of polystyrene are made by anionic polymerization of at least 
one .alpha.,.beta.-unsaturated aromatic monomer followed by end capping 
the living polymer to introduce an .alpha.,.beta.-unsaturated terminal 
group as described in U.S. Pat. Nos. 3,842,059 and 3,862,098. The 
disclosures of which are incorporated by reference thereto as if fully set 
forth herein. The preferred chains may be of a homopolymer or random or 
block copolymer of polystyrene made from .alpha.,.beta.-unsaturated 
aromatic monomer(s) selected from styrene, alpha-methyl styrene, and vinyl 
toluene. In random or block copolymer, other .alpha.,.beta.-unsaturated 
monomers may be incorporated in a minor amount. An example of a macromer 
of polystyrene made by anionic polymerization with butyl lithium has a 
structure of 
##STR9## 
wherein m is an integer in the range from 2 to 250. 
The macromers of polymethacrylate are made by group transfer polymerization 
of at least one alkyl methacrylate as described in U.S. Pat. Nos. 
4,554,324 and 4,551,388. The disclosures of which are incorporated by 
reference thereto as if fully set forth herein. The preferred chains may 
be of a homopolymer or random or block copolymer of polymethacrylate made 
from alkyl methacrylate(s) selected from methyl methacrylate and butyl 
methacrylate. 
The macromers of polyesters and polyethers made by ring-opening 
polymerization generally are terminated with a hydroxyl group at one end 
as shown in structure (LM1) and (LM2). In some cases, it is highly 
desirable to cap the hydroxyl group with a non-reactive group so that the 
new terminal group will not react with the reactive functional groups of 
the comb, or interfere with the subsequent conversion of the reactive 
groups of the comb into other groups or the utilization of the comb as a 
reactive modifier, or convert the hydroxyl group into another reactive 
group so that the new reactive group the macromer may be used as 
additional reactive site for the comb to react with the thermoset when the 
comb is used as a reactive modifier. The end-capping and the conversion of 
the hydroxyl group of the macromers is not narrowly critical and a variety 
of esterification and etherification reactions may be used to cap the 
terminal hydroxyl group, as for example, disclosed in U.S. Pat. Nos. 
2,998,409 and 3,507,927; or, by reacting with an alkylisocyanate or, by 
reacting with diazomethane or, by reacting with acrylonitrile or 
trialkychlorosilane. The conversion of the hydroxyl group of the macromers 
into carboxyl group is disclosed in U.S. Pat. No 4,786,749. 
##STR10## 
of the comb is 
##STR11## 
wherein, [R].sub.n, is 
##STR12## 
[M].sub.m is 
##STR13## 
and, 
Z is --OH. 
The molecular weight of the copolymer made by the foregoing free-radical 
polymerization is highly dependent on the amount of the initiator used. It 
is generally believed that the possession of terminal reactive functional 
groups is one of important factors for an elastomer to be an effective 
modifier. The terminal functional group enables the modifier to build up 
its own molecular weight and to form chemical bonding between a reactive 
modifier and a thermoset. The build up the molecular weight of the 
microphase of the modifier to promote its elastomeric properties and the 
formation of bonding to provide a high interfacial interaction between the 
microphase and the thermoset matrix. Both are important for toughening. 
However, a relatively high molecular weight reactive modifier is less 
desirable or not effective since it provides less reactive functional 
groups per weight of the modifier or not enough functional groups to react 
with the thermoset to achieve the necessary interaction. Another 
disadvantage of high molecular weight is the difficulty in handling as a 
modifier. Generally most thermosets are a pourable liquid, a very high 
molecular weight modifier with Mn probably greater than 80,000 may be a in 
handling as a modifier. Generally most thermosets are a pourable liquid, a 
very high molecular weight modifier with Mn probably greater than 80,000 
may be a solid which is difficult to dissolve into the resin; and, Mn in 
the range near 30,000 is either a sticky gum which is extremely difficult 
to handle or a liquid with extremely high viscosity, which is 
non-plurable. Even if the difficulty of handling the high molecular weight 
modifier is solved, the uncured thermoset, after blending in with the 
modifier, may have to high of a viscosity to be castable or to be handle 
which severely limits its applications. Consequently, the molecular weight 
of the reactive comb of the present invention is in the range from 1,000 
to 20,000, preferably from 1,500 to 10,000, most preferably from 3,000 to 
6,000. In order to obtain the molecular weight in a desirable range, the 
amounts of the initiator to be used in the polymerization is in the range 
from 1 to 20 part by mole per 100 part by moles of monomer(s) and 
macromer, preferably from 2 to 10. The reactive comb made with a initiator 
less than 1 part by mole per 100 part by moles of monomer(s) and macromer 
does not provide enough reactive groups per weight of the modifier and its 
viscosity is too high for most applications. 
It is also generally believed that a reactive modifier shall be an 
elastomer. Consequently, the elastomeric backbone is a predominate 
component of the comb copolymer and present in the range from 60% to 93% 
by weight of the comb copolymer, preferably from 75% to 95 wt % by weight; 
the pendent chain or chains from a macromer are minor component and 
present in the range from 3% to 40% by weight of the comb copolymer, 
preferably from 5% to 25% by weight. 
The E-monomer is a major component for the elastomeric backbone and is 
present in the range from 65% to 100% by weight of the backbone component 
so as to provide an elastomeric backbone component having a glass 
transition temperature, Tg, in the range from -100.degree. C. to 
25.degree. C., preferably, from -80.degree. C. to 0.degree. C. If the 
backbone component is not compatible with the pendent chains of the comb 
copolymer, It will show its own Tg separately from the Tg of the pendent 
chains. If both Tg's are not separable because of total miscibility of the 
two, the Tg of the backbone component is quantified by making a similarly 
(as the comb) terminally functionalized homopolymer or copolymer of the 
ethylenically unsaturated monomer used to provide the backbone in the 
absence of a macromer. The molecular weight of the homopolymer or 
copolymer is substantially the same molecular weight as that made, or 
expected to be made, in the backbone. The Tg of the homopolymer or 
copolymer is then measured. The preferable E-monomer is a C1-C8 alkyl 
acrylate which is not expensive and provides very favorable polymerization 
with a free-radical initiator. The comb copolymer made is free of 
olefinical unsaturation and can be used as a modifier for applications 
requiring ultra-violet and thermo-oxidative resistance. 
The elastomeric backbone component may be optionally consisting of from 0% 
to 30 wt % of a R-monomer and from 0% to 10 wt % of a D-monomer by weight 
of the backbone component. The R-monomer is incorporated to lower cost, to 
decrease the elasticity of the backbone to improve the handling of the 
comb copolymer, such as to decrease stickiness of the resulting comb 
copolymer, and/or to improve the miscibility of the backbone component 
with a thermoset so less pendent chains are required. Generally, the 
incorporation of a R-monomer will increase the Tg of the backbone 
component, therefore the amount of the R-monomer incorporated shall be 
limited so as the Tg of the backbone component will not be higher than 
25.degree. C. In the preferred embodiment, no R-monomer is used with at 
least one E-monomer of alkyl acrylate. When E-monomer is a diene, it is 
preferable to copolymerize with 5% to 25% by weight of a R-monomer of 
acrylonitrile. 
A D-monomer may be incorporated to provide additional reactive functional 
groups randomly distributed along the backbone of the comb copolymer to 
react with a thermoset. Additional functional groups may be desirable to 
improve the interfacial interaction through additional bonding with a 
thermoset. However, too much bonding may not be favorable because it forms 
a highly crosslinked microphase which losses elasticity cannot function as 
a toughener. The functionality of D-monomer may be different from that of 
the terminal functional group so as to provide different reactivity toward 
a thermoset. A D-monomer may also be incorporated for the purposes to 
improve the miscibility of the backbone component with a thermoset so as 
less pendent chains are required or, in a few rare cases, to provide 
functional groups so as the resulting comb copolymer may be further 
modified before using. It is very important to select an appropriate 
D-monomer so that its functional group does not have significant 
reactivity with the terminal functional groups of the comb so as a 
premature reaction between them will not occur or, if does occur, will not 
be significant before using as a modifier. If different functionality 
between the terminal groups and the functional group of a D-monomer is 
desirable, when the terminal groups of the backbone are carboxyl, a 
D-monomer with functionality of hydroxyl, epoxy, or thio may be selected. 
The reaction between them is so low at ambient temperature, so as no 
significant increase in viscosity is observed for days, or even for 
months. When the terminal groups are hydroxyl, a D-monomer with 
functionality of carboxyl, epoxy, or thio may be selected. A D-monomer 
with isocyanato group is highly reactive and an initiator with easily 
hydrolyzable groups, such as ester or trimethysilyloxy group, has be used. 
The reactive terminal groups of the comb copolymer are obtained by 
hydrolysis of the ester or trimethysilyloxy groups after desirable 
modification the comb copolymer has been carried out through isocyanato 
groups. 
The pendent chain or chains of a macromer is a minor component of the comb 
copolymer and present in the range from 3% to 40% by weight of the comb 
copolymer, preferably from 5% to 25% by weight. The pendent chain or 
chains function as a compatibilizer for the backbone and makes the comb 
copolymer miscible with a thermoset. It is necessary to incorporate 
pendent chains of the present invention to an immiscible linear reactive 
modifier to make the resulting comb copolymer miscible. It may be 
advantageous to incorporated pendent chains to an already miscible linear 
reactive modifier, such as CTBN, to further improve miscibility. The 
pendent chain or chains also function as a compatibilizer for the 
elastomeric microphase to increase the interfacial interaction with the 
thermoset matrix after curing. 
Once the elastomeric backbone component of the comb copolymer is chosen, 
the miscibility of the comb copolymer can be specifically tailored for a 
thermoset by selecting the type of macromer and the amounts of macromer to 
be incorporated. As the amounts of macromer increases, the miscibility 
increases and eventually the reactive comb copolymer becomes a 
flexibilizer instead of a toughener. The macromer of the present invention 
is generally a relatively narrow molecular weight distribution and provide 
the pendent chains which are randomly distributed along the backbone and 
substantially the same in chain length. The macromer of the present 
invention has a structure of (LM) and is selected from the group of 
polyester, polyether, polystyrene or polymethacrylate with repeating units 
in the range from 2 to about 250, preferably in the range from 2 to 100, 
most preferably in the rang from 3 to 25. The number of pendent chains per 
the comb copolymer is dependent on the amount of a macromer and molecular 
weight of a macromer. With a fixed amount of a macromer, the number of 
pendent chains per the comb copolymer is expected to be less for a 
macromer having higher molecular weight. As to be expected, the various 
species of comb copolymer made will have a structure consistent with the 
expected statistical distribution, a majority of the comb molecules having 
the expected number of pendent chains sought, fewer molecules having only 
one or two pendent chains, and still fewer with no chains. 
It shall be noted that the terminal group, Z, of the macromer will become 
the terminal group of the pendent chains of a comb copolymer. The terminal 
group, Z, may be non-reactive. If Z is a reactive functional group having 
the same functionality of the terminal functional groups of the comb 
copolymer, Z functions as an additional reactive site for curing. If the 
functionality of Z is different from that of the terminal reactive groups 
of the comb copolymer, then it is very important to select an appropriate 
functional group which does not have significant reactivity with the 
terminal functional groups of the comb or the functional groups of 
D-monomer, if present, so as a premature reaction between or among them 
will not occur or, if does occur, will not be significant before using as 
a modifier. 
One preferred method for making the comb is by solution polymerization in 
an essentially non-aqueous organic solution such as a ketone, in which the 
ethylenically unsaturated monomer(s), the macromer, and the initiator are 
soluble at the polymerization temperature, and after the polymerization 
reaction is complete, the comb copolymer formed is typically also soluble 
in the solvent. In a typical production of a comb with an acrylate 
backbone and polylactone chains, the solution polymerization may be done 
with ADVA to which a small amount of water, less than 10 parts per 100 
parts of acetone, has been added to enhance the miscibility of ADVA in 
acetone, the preferred solvent. The polymerization may be carried out at a 
temperature in the range from 10.degree. C. to about 150.degree. C., 
depending upon the half-life of the initiator used. For active acrylate 
monomer, it may take up from 2 to 10 hours to achieve high conversion; for 
less active diene monomer, it may take up to 48 hours. The polymerization 
may be carried out in various ways. It may be carried by adding all 
monomer(s), macromer, and initiator to start the polymerization; or by 
adding all initiator first then metering in monomer(s) and macromer; or by 
adding all initiator and part of monomer(s) and macromer (referred to as 
background monomers) then metering in the remaining monomer(s) and 
macromer; or by metering monomer(s), macromer, and initiator. It is 
preferable to meter in a mixture of monomers and macromer to improve the 
uniformity of the composition of the comb copolymer. 
It has also been discovered that the reactive modifier with terminal vinyl 
or amino groups, which can not be directly produced from polymerization 
with an initiator having a corresponding functional group, can be produced 
by converting the terminal carboxyl or hydroxyl groups of comb copolymer 
obtained from a free radical polymerization using a difunctional 
initiator. It has also been discovered that the reactive modifier with 
certain terminal groups, which is not economically produced from an 
initiator with a corresponding functional group or is not reactive enough 
with a thermoset, can be produced by converting more readily available 
terminal carboxyl or hydroxyl groups of comb copolymer. It has also been 
discovered that the terminal function groups of the comb may be converted 
to provide desirable or latent reactivity with the thermoset. Therefore 
the comb copolymer of the present invention may be obtained by converting 
the terminal functional groups of the comb (I) obtained by free-radical 
polymerization. Such converted comb copolymer may be represented by the 
structure 
EQU R.sup.e1 --Y--X--Q--X--Y--R.sup.e1 (III) 
wherein, R.sup.e --Y--is directly derived from the terminal functional 
group, R.sup.e --, of the comb (I) and R.sup.e1 --, selected from the 
group consisting of carboxyl, hydroxyl, amino, epoxy, vinyl, and thio 
group, is the new terminal functional group of the converted comb 
The conversion of functional groups may be carried out by known processes 
taught in the prior art. From a terminal carboxyl group, the conversion 
into a vinyl group may be made by reacting with glycidyl methacrylate or 
allyl glycidyl ether as disclosed in U.S. Pat. No. 4,129,713, 4,013,710, 
and 3,925,330; the conversion into a hydroxyl group may be made by 
reacting with ethylene oxide as disclosed in U.S. Pat. Nos. 3,712,916, 
3,699,153, 3,551,471 and 3,712,916, or with ethylene glycol or a 
polyakylene glycol; the conversion into an amino group may be made by 
reacting with a diamine, preferable with different reactivity, such as 
aminoethyl piperazine as disclosed in U.S. Pat. No 4,133,957, 3,925,330, 
and 3,551,471; and, the conversion into an epoxy group may be made by 
reacting with a diepoxy compound, such as Epon.RTM. 828. From a terminal 
hydroxyl group, the conversation into a vinyl group may be made by 
reacting with a ethylenical unsaturated isocyanate, such as 
2-isocyanatoethyl acrylate; and, the conversation into a carboxyl group 
may be made by reacting with an anhydride as disclosed in U.S. Pat. No. 
4,786,749. In some cases, it may be more preferable to be carried out in 
two steps, such as the conversion of carboxyl or hydroxyl group into an 
epoxy group by reacting with epichlorohydrin and then with NaOH or the 
conversion of carboxyl into a vinyl group by reacting with a diepoxy 
compound then methacrylic acid. 
When a terminal carboxyl group is converted into a hydroxyl group by 
reacting with ethylene oxide, the R.sup.e --Y--in (III) is 
EQU HO--CH.sub.2 CH.sub.2 OOC-- 
Wherein, R.sup.e --is HO--(hydroxyl group); and, into a vinyl group by 
reacting with glycidyl acrylate, the R.sup.e --Y--in (III) is 
EQU CH.sub.2 =CHCOO-CH(OH)CH.sub.2 OOC-- 
Wherein, R.sup.e --is CH.sub.2 =CHCOO--(vinyl group). 
The comb copolymer of the present invention of structure (I) can also be 
produced by attaching a pendent chain or chains to a copolymer with 
reactive ends (referred as starting copolymer), made by copolymerizing, in 
absent of a macromer, at least one E-monomer and D-monomer, optionally 
with R-monomer with a difunctional initiator, with coupling or 
condensation through the functional group of D-monomer randomly 
distributed along the backbone. Such comb copolymer having a structure of 
(I) wherein--Q--may be represented by a structure: 
##STR14## 
wherein [M.sub.o ], [M], Z, n', and n" are the same as in (II); [R] is 
derived from the D-monomer, and L is a linkage to the backbone which is 
contributed by reaction of the function group of the D-monomer group with 
a monofunctional or difunctional, most preferably monofunctional, 
polyester, polyether, polystyrene, or polymethacrylate having repeating 
units of [M]m; Mo, M, Z, m, n' and n" as previously defined. 
It is important to select the D-monomer with its functionality different 
from that of the terminal groups of the starting copolymer, more 
preferably, they have substantially different reactivity with the 
subsequent grafting reaction, so that the grafting will not occur 
predominately at the terminal groups. As an illustrative example, a 
starting copolymer of (BA/HEA) is made by a free radical polymerization, 
of 90 wt % of butyl acrylate (BA) and 10 wt % of 2-hydroxyethyl acrylate 
(HEA), in the absent of a macromer, with ADVA as an initiator, as 
described in the foregoing process. The copolymer of (BA/HEA) so made 
possesses carboxyl groups at both ends and hydroxyl groups on the HEA 
repeating units randomly distributed along the elastomeric backbone. The 
starting copolymer is then reacted with a monofunctional polyester or 
polyether having a terminal --NCO group. Because the terminal carboxyl 
group is substantially less reactive then the hydroxyl group, grafting of 
the pendent chains occurs with formation of a carbamate linkage by 
coupling with the hydroxyl group of the starting copolymer. The reactive 
comb copolymer of the present invention so made will have carboxyl groups 
at both end of elastomeric backbone of butyl acrylate and pendent chains 
of polyester or polyether attached to the backbone with carbamate 
linkages. The mono-functional polyester or polyether having a terminal 
-NCO group may be obtained by reacting a diisocyanate, preferably with 
different reactivity, with a mono-hydroxyl-terminated polyester or 
polyether at a one to one molar ratio. Grafting may also be carried, 
though less preferable, by reacting a diisocyanate with the starting 
copolymer first then coupling with a hydroxyl terminated polyester or 
polyether, or by reacting a diisocyanate with the starting copolymer and a 
hydroxyl terminated polyester or polyether together. The hydroxyl groups 
of the starting comb may also react with a anionic living polystyrene 
which results in a ether linkage. Dependent on the desirable number of 
pendent chains, not all of the hydroxyl groups of the starting comb have 
to be coupled. 
It is known to a person skilled in the art to select an appropriate 
D-monomer so that the functional group of D-monomer will not react with 
the terminal functional groups of the starting copolymer prematurely 
before grafting the pendent chains. Consequently, it is more preferable to 
used an initiator having easily hydrolyzable groups to prepare the 
starting copolymer. The easily hydrolyzable group, such as ester or 
trimethysilyloxy group, is generally inert to the subsequent grafting 
reaction. As another illustrative example, a starting copolymer is made by 
a free radical polymerization, of 90 wt % of butyl acrylate (BA) and 10 wt 
% of 2-isocyanatoethyl acrylate (ICEA), in the absent of a macromer, with 
dimethyl ester of ADVA as an initiator, as described in the foregoing 
process. The copolymer so made possesses ester groups at both ends and 
isocyanato groups on the ICEA repeating units randomly distributed along 
the elastomeric backbone. The starting copolymer is then reacted with a 
hydroxyl terminated polyester or polyether, preferably monofunctional, to 
form a carbamate linkage by coupling with the isocyanato group of the 
starting copolymer. The reactive comb copolymer of the present invention 
will be obtained after hydrolysis. 
The reactive comb copolymer of the present invention is useful as a 
reactive modifier for thermosetting resins, such as acrylic resin, 
polyester resin, polyurethane resin, epoxy resin, vinyl ester resin, and 
unsaturated polyester resin, as a toughener and/or a flexibilizer by 
proper selection of the terminal reactive groups to react with the target 
thermoset and the pendent chains for miscibility. The reactive comb 
copolymer of polyacrylate, which is free of olefinic unsaturation, is 
particularly useful for applications require ultra-violet light and/or 
thermo-oxidative resistance. It is known in the art that a 
carboxyl-terminated or an epoxy-terminated modifier is more suitable for 
acrylic resins, polyester resins, and epoxy resins; a hydroxyl-terminated 
or a thio-terminated modifier is more suitable for acrylic resins, 
polyester resins, and polyurethane resins; and, a vinyl-terminated 
modifier is more suitable for vinyl ester resins, and unsaturated 
polyester resins. Not every pendent chain of the comb polymer is effective 
to improve miscibility with all the thermosets. The pendent chains of a 
polyester or a polyether are the most favorable and effective on all 
foregoing mentioned thermosets. However, the pendent chains of a 
chlorine-containing polyepichlorohydrin may not be suitable for 
polyurethane resins because the isocyanato group may react with the 
chloride. The pendent chains of polystyrene are effective with acrylic 
resins but not with epoxy resins. Dependent of the type, a thermoset may 
be used, for example, in bonding and adhesives, laminates and composites, 
flooring, pipes, and coatings. Toughening will improve peel and shear 
strength in adhesive; make composites less brittle; and, improve impact 
and chip resistance in high solid, water base, solution, and powder 
coatings. The reactive comb copolymer of the present invention is also 
useful as a compatibilizing agent and dispersion agent for others reactive 
modifiers. When it is used as a compatibilizing agent, it will make an 
immiscible reactive modifier or a reactive modifier with relatively poor 
miscibility miscible with a thermoset or improve miscibility of a reactive 
modifier already miscible with a thermoset. When the reactive comb is used 
as a dispersion agent, it will disperse an immiscible reactive modifier as 
stable microparticles in a thermoset before and after curing. 
In the following examples which illustrate the invention, all reference to 
parts is to parts by weight, unless otherwise stated (`gm` and `g` are 
interchangeable). 
The following is a glossary of identifying names and symbols used in the 
following examples: 
Symbols: 
phr--per 100 parts by weight of resin or polymer 
Ephr--equivalent per 100 g of resin or polymer 
CEW--carboxyl equivalent weight 
CT--carboxyl-terminated 
HT--hydroxyl-terminated 
ET--epoxy-terminated 
AT--amine-terminated 
VT--vinyl-terminated 
Conventional Monomers: 
BA--n-butyl acrylate 
EHA--2-ethylhexyl acrylate 
HEA--hydroxyethyl acrylate 
AA--acrylic acid 
AA Dimer--dimer of acrylic acid, Sipomer.RTM. .beta.-CEA obtained from 
Alcolac Co. 
CL--caprolactone 
ECH--epichlorohydrin 
HEMA--2-hydroxyethyl methacrylate 
Macromers: 
MPCL--macromer of polycaprolactone. 
MPCL4--acrylic-terminated MPCL with molecular weight of 420 as calculated 
from hydroxyl number of 134 mg KOH/g. 
MPCL6--acrylic-terminated MPCL with molecular weight of 640 as calculated 
from hydroxyl number of 87.8 mg KOH/g. 
MPCL21--acrylic-terminated MPCL with molecular weight of 2100 as calculated 
from hydroxyl number of 26.7 mg KOH/g. 
MPCL7--acrylic-terminated MPCL with molecular weight of 685 as calculated 
from hydroxy number of 82 mg KOH/g. 
MPCL12--acrylic-terminated MPCL with molecular weight of 1256 as calculated 
from hydroxyl number of 45.5 mg KOH/g. 
MPECH--macromer of polyepichlorohydrin. 
MPECH1--acrylic-terminated MPECH with molecular weight of 856 prepared 
according to U.S. Pat. No. Re. 31,468 to Hsu from epichlorohydrin and 
hydroxyethyl acrylate with triethyloxonium hexafluorophosphate. 
Free-radical Initiators: 
ADVA--4,4'-azobis-(4-cyano-pentanoic acid) 
AHMP--2,2'-azobis[2-(hydroxymethyl) propionitrile] 
Reactive Polymers: 
CTA--carboxyl-terminated polyacrylate 
MCTA--macromer modified carboxyl-terminated polyacrylate, a reactive comb 
copolymer of the present invention 
HTA--hydroxyl-terminated polyacrylate 
MHTA--macromer modified hydroxyl-terminated polyacrylate, a reactive comb 
copolymer of the present invention 
MATA--macromer modified amine-terminated polyacrylate, a reactive comb 
copolymer of the present invention 
META--macromer modified epoxy-terminated polyacrylate, a reactive comb 
copolymer of the present invention. 
MVTA--macromer modified vinyl-terminated polyacrylate, a reactive comb 
copolymer of the present invention 
CTBN--carboxyl-terminated butadiene and acrylonitrile copolymer. 
CTBNX8--carboxyl-terminated butadiene and acrylonitrile copolymer, 
Hycar.RTM. CTBN 1300X8, obtained from BF Goodrich Co. contains 18 wt % of 
acrylonitrile, has a carboxyl number of 29, and Brookfield viscosity of 
135,000 cps at 27.degree. C. 
CTBNX13--carboxyl-terminated butadiene and acrylonitrile copolymer, 
Hycar.RTM. CTBN 1300X13, obtained from BF Goodrich Co. contains 26 wt % of 
acrylonitrile, has a carboxyl number of 32, and Brookfield viscosity of 
500,000 cps at 27.degree. C.

EXAMPLES 1-4 
Four reactive comb copolymers, identified as MCTA1-4, having a backbone of 
polyacrylate with a carboxyl group at each end, and entrained in the 
backbone are pendent chains derived from a macromer of polycaprolactone, 
were synthesized. MCTA1 is the first of four comb copolymers made by 
copolymerizing 85 parts BA and 15 parts MPCL6 (MW=640) with ADVA by a 
free-radical polymerization in a 2-L jacketed glass Buchi reactor. 
72 gm of MPCL are dissolved in 408 gm of BA in a container, and the 
solution purged with nitrogen to remove any oxygen present. Separately, 
16.3 wt % solution of ADVA initiator in an acetone and water mixture in a 
85:15 ratio by wt was prepared. 
The reactor is charged, in the following order, starting with 185.5 gm 
acetone, adding 106 gm mixed monomer solution referred to as the 
"background monomers", and 294.5 gm acetone solution of ADVA containing 48 
gm of neat ADVA. The reactor containing ADVA/monomers=10/90 by wt or 
5.2/94.8 by mole, was evacuated until the acetone boiled (about 20" Hg), 
then pressurized to 30 psig with nitrogen, and the procedure repeated 
three times. 
The reactor was then heated to 80.degree. C. over about 45 min., the 
remaining mixed monomer solution, referred to as "metering monomers", 
metered into the reactor over 4 hours, the temperature being maintained at 
80.degree. C. and the pressure at 30 psig. After the completion of 
metering, the reaction mass was post polymerized for an additional one 
hour, resulting in a total polymerization time of 5 hr. At the end of post 
polymerization, the reactor was cooled down, then the polymer solution was 
blown down to an one-gallon jar. Total solids obtained was 56.7%. 
Subsequently, 0.72 g of Irganox 1010 (antioxidant) is added to the polymer 
solution, which was filtered and washed with water, and then the solvent 
and unpolymerized BA were removed using a rotary evaporator under vacuum 
and heat. 
The preparation of the first comb MCTA1 yielded 440 gm of very light 
yellow, clear liquid polymer corresponding to an yield of 83% despite some 
small loss of polymer during each of the filtration, .washing, drying and 
transfer steps. 
The foregoing polymerization procedure and conditions are maintained for 
each of the preparations for three additional comb copolymers, MCTA2, 
MCTA3 and MCTA4. The polymerization conditions are summarized below: 
______________________________________ 
Temperature, .degree.C. 80 
Pressure, psig 30 
background monomers, gm 106 
Metering monomers, gm 374 
Monomer Metering time, hr 4 
Post polymerization time, hr 
1 
Total time of polymerization, hr 
5 
______________________________________ 
In four examples, the polymerization conditions, macromer, butyl acrylate 
(BA), and initiator used were the same with the amounts of the macromer 
varied as set forth in Table I below, in which the results of each run, 
and the characterization of the comb copolymers formed, are also given: 
TABLE I 
______________________________________ 
MPCL/BA MCTA1 MCTA2 MCTA3 MCTA4 
by wt 15/85 10/90 20/80 25/75 
______________________________________ 
Polymerization: 
Monomer BA 
wt, gm 408 432 384 360 
moles, 3.18 3.37 3.00 2.81 
Macromer MPCL6 
Wt., gm 72 48 96 120 
moles 0.113 0.075 0.15 0.188 
Total Solids, % 
56.70 63.39 57.04 57.62 
Product, gm 440 422 415 416 
Yields, % 83 79 78 78 
Heat loss, % 0.86 0.67 0.75 0.81 
Characterization: 
MPCL wt % in 13 10 18 24 
polymer by NMR 
Carboxyl, Ephr 
0.036 0.034 0.034 0.035 
Acid No. 20.20 19.10 19.10 19.60 
CEW 2778 2941 2941 2857 
GPC: 
Mn .times. 10.sup.3 
5.46 5.04 5.40 5.69 
Nw .times. 10.sup.3 
37.00 30.00 35.00 40.90 
Mw/Mn 6.77 5.96 6.49 7.18 
Peak .times. 10.sup.3 
18.30 19.40 17.30 20.20 
Brookfield Viscosity 
154 122 96 98 
at 27.degree. C. cps .times. 10.sup.3 
______________________________________ 
The examples show that the comb copolymers with varying amount of macromer 
can be made in high yield and the yield, carboxyl content, and molecular 
weight are substantially insensitive to the change in the amount of 
macromer used, and that up to 25% by wt of each macromer is entrained in 
the comb. A viscosity in the range from about 100,000-150,000 cps is 
deemed substantially similar with respect to using the modifier. 
As-shown in Table I, both acid numbers and Brookfield viscosities of four 
comb copolymers are comparable to those for commercial Hycar.RTM. CTBN 
1300x8. 
Glass transition temperatures were determined by Perkin-Elmer DSC-2 
differential scanning calorimeter under helium. The comb copolymers have a 
Tg in the range from -44.degree. C. to -49.degree. C., Macromer MPCL6 has 
a Tg at -69.degree. C. and a homopolymer of butyl acrylate has a Tg at 
-45.degree. C. 
Proton NMR spectra were acquired at 500 MHz using a Bruker AM-200 
spectrometer in chloroform-d at 30.degree. C. using TMS as a reference. 
The proton NMR spectra of comb copolymers show characteristic chemical 
shifts of n-butyl acrylate repeating units at 4.06 ppm for --CH.sub.3 
protons, 1.39 ppm and 1.64 ppm for C-3 and C-2 methylene protons, 
respectively, and at 4.06 ppm for --OCH.sub.2 protons corresponding to the 
butyl group and at 2.3 ppm for .alpha.-CH proton and 1.9 ppm for 
.beta.-CH.sub.2 protons corresponding to the backbone component. The 
characteristic chemical shifts of MPCL repeating units appear at 4.06, 
2.30, 1.65, and 1.4 ppm corresponding to the repeating units of CPL, at 
4.3(m) ppm for the ethylene oxide unit of the terminal acryloylethyl 
group, and at 3.6 ppm as a triplet for the protons of the methylene group 
of the CPL unit adjacent to the terminal hydroxyl group. The absence of or 
extremely small of resonance signals in the range from 5.5 to 6.5 ppm 
indicates that the residue BA and unpolymerized MPCL are negligible in the 
final MCTA. The composition of comb copolymers are determined by the 
integration of the spectra and shown in Table I. 
Carbon-13 NMR spectra were acquired at 20.1 MHz using Bruker WP-80 
spectrometer in chloroform-d with internal tetramethylsilane reference at 
30.sup.2 .degree. C. The carbon-13 NMR spectra of comb copolymers show 
characteristic chemical shifts of n-butyl acrylate repeating units at 
13.8, 19.1, 30.7, and 64.5 ppm for --CH.sub.3, C-3, C-2, and C-1 
(--OCH.sub.2) methylene carbons of the n-butyl group, respectively, at 
174.6 ppm for the carbonyl carbon, and at 41.5 ppm for .alpha.-CH carbon 
and 35.3 ppm for .beta.-CH.sub.2 carbon corresponding to the backbone 
component. The characteristic chemical shifts of MPCL repeating units 
appear at 33.7, 25.5, 24.6, and 64.1 ppm for methylene carbons and 173.6 
ppm for the carbonyl carbon corresponding to the repeating units of CPL, 
and at 62.3 ppm the carbon of the methylene group of the CPL unit adjacent 
to the terminal hydroxyl group. 
GPC (gel permeation chromatography) analysis was carried out at 40.degree. 
C. using Water's GPC model 200 instrument with columns packed with 
styragel. THF was used as a carrier solvent. The columns were calibrated 
by using standard narrow distribution polystyrene. All molecular weights 
of MCTA polymers determined by GPC are in terms of polystyrene equivalent 
molecular weight and shown in Table I. Molecular weight distribution 
(Mw/Mn) of MCTA is relatively broad. The broad Mw/Mn is characteristic of 
a free-radical polymerization. 
EXAMPLES 5-8 
In a manner analogous to that illustrated in the foregoing Example 1, 
additional MCTA polymers were synthesized with varied mol wts of MPCL in 
the range from 420 to 2100. The first column lists the results with the 
lowest mol wt; the second column repeats the data of MCTA1, for 
comparison. The polymerization were carried out at a fixed MPCL/BA ratio 
of 15/85 using 72 gm of macromer and 408 gm of BA in acetone with 294.5 gm 
of the same 16.3% solution ADVA initiator, under the same polymerization 
conditions at 80.degree. C., 106 gm of background monomer, and 374 gm 
metering monomers, with the same polymerization conditions shown in 
Examples 1-4. 
All polymerization gave excellent yields of about 80% or better. All MCTA 
copolymers show characteristic NMR chemical shifts as described in 
Examples 1-4. The composition as determined by NMR, carboxyl content, GPC 
data, and Brookfield viscosity are summarized in Table II. 
TABLE II 
__________________________________________________________________________ 
Example 
5 1 6 7 8 
MCTA5 
MCTA1 
MCTA6 
MCTA7 
MCTA8 
__________________________________________________________________________ 
Macromer: 
ID MPCL3 
MPCL6 
MPCL7 
MPCL12 
MPCL21 
MW 420 640 686 1256 2100 
moles 0.171 
0.113 
0.105 
0.057 
0.034 
Total solids % 57.58 
56.70 
57.38 
57.93 
58.14 
Product, g 420 440 423 423 415 
Yield, % 79 83 80 80 78 
Heat loss, % 0.054 
0.859 
0.031 
0.027 
0.072 
MPCL wt % in polymer determined by NMR 
14 13 15 17 15 
Carboxyl, Ephr 0.037 
0.036 
0.034 
0.035 
0.036 
Acid No. 20.76 
20.20 
19.07 
19.64 
20.20 
CEW 2702 2778 2941 2857 2777 
GPC: 
Mn .times. 10.sup.3 5.3 5.5 5.2 5.5 5.0 
Mw .times. 10.sup.3 34.9 37.0 30.1 32.0 22.6 
Mw/Mn 6.6 6.8 5.8 5.8 4.5 
Peak .times. 10.sup.3 16.0 18.3 15.6 19.2 16.0 
Brookfield Viscosity 168 154 127 222 ND* 
at 27.degree. C. cps .times. 10.sup.3 
__________________________________________________________________________ 
*ND = not determined 
The foregoing data in Table II show that the comb copolymers of this 
invention with varying length of pendent chains can be made in high yield 
and the yield, carboxyl content, and molecular weight are substantially 
insensitive to the change in the molecular weight of macromer used. 
EXAMPLE 9 
In a manner analogous to the illustrated in the foregoing Example 1, MCTA 
polymer was synthesized with MPCL6 at a MPCL/BA weight ratio of 15/85 
except at a higher temperature, 95.degree. C., and with less ADVA 
(compared to Example 1) as an initiator (202 gm of the 16.3% solution used 
=33.3 gm ADVA neat, ADVA/monomers=9.2/90.8 by wt or 3.6/96.4 by mole). The 
polymerization at 95.degree. C. was completed in 2 hrs (1 hr metering, and 
1 hr post-polymerization) compared to 5 hrs at 80.degree. C. The 
polymerization conditions and characterization of the comb copolymer are 
presented below in Table III. 
EXAMPLES 10-12 
The following examples provide evidence that the functionality of the comb 
may be increased by adding a D-monomer. For additional carboxyl 
functionality in a comb with a carboxyl-terminated backbone, the D-monomer 
may be acrylic acid, or a dimer of acrylic acid. Whether in a comb with a 
carboxyl- or a hydroxyl-terminated backbone, hydroxyethyl acrylate (HEA) 
may be used as the D-monomer to introduce additional hydroxyl 
functionality. 
In a manner analogous to that illustrated in the foregoing Example 1, MCTA 
polymer was synthesized with 15 parts MPCL6 (72 g) and the remainder 
portioned between BA and a third monomer (D-monomer), AA and AA dimer (1 
or 2 parts) with 48 g of neat ADVA. Evidence that the D-monomer is 
entrained in the comb is the higher acid number and low carboxyl 
equivalent weight of the polymers which are given in the following Table 
III. 
TABLE III 
______________________________________ 
Example 
9 10 11 12 
MPCL/BA/D- MCTA15 MCTA16 MCTA17 MCTA18 
monomer 15/85 15/84/1 15/83/2 
15/83/2 
______________________________________ 
Polymerization: 
BA, 
g 408 327 327 327 
moles 3.18 2.55 2.55 2.55 
AA, 
g -- 4.20 8.40 -- 
moles -- 0.06 0.12 -- 
AA Dimer, 
g -- -- -- 8.40 
moles -- -- -- 0.06 
Background, gm 
192 85 85 85 
Metering, gm 288 300 300 300 
Metering time, hr 
1.0 3.5 3.5 3.5 
Polymerization Temp 
95.degree. C. 
80.degree. C. 
80.degree. C. 
80.degree. C. 
Post Pzn Time, hrs 
1.0 0.5 0.5 0.5 
Total Time, hrs 
2.0 4.0 4.0 4.0 
Total Solids, % 
56.82 53.92 55.63 57.13 
Product, gm 422 300 321 334 
Heat loss, % 0.056 0.380 0.260 0.340 
Characterization: 
Carboxyl, Ephr 
0.033 0.070 0.082 0.069 
Acid No. 18.51 39.27 46.00 38.71 
CEW 3030 1428 1219 1449 
Brookfield Viscosity 
248 416 842 429 
@ 27.degree. C. 
cps .times. 10.sup.3 
______________________________________ 
The foregoing data in Table III show that the comb copolymers of this 
invention with a D-monomer can be made in high yield. The incorporation of 
AA or AA dimer increases viscosity substantially. 
EXAMPLE 13 
In a manner analogous to that illustrated in the foregoing Example 1, a 
comb copolymer, MCTA13, was synthesized with ethylhexyl acrylate (EHA) and 
MPCL6 (MPCL/EHA 15/85) under the same conditions. The results are set 
forth in Table IV, below (after Example 15). The data in Table IV show 
that the comb copolymer having EHA as a backbone component can also be 
made in as high yield as the copolymers having BA as a backbone component 
as made in foregoing examples. 
EXAMPLE 14 
In a manner analogous to that illustrated in the foregoing Example 1, MCTA 
polymer was synthesized with BA and MPECH1 (mol wt 856) in the MPECH/BA 
ratio of 15/85 by wt to introduce a polyether as pendent chains of the 
comb. The objective is to synthesize a carboxyl-terminated comb copolymer 
modified with a polyether. The proton NMR spectra of MCTA show 
characteristic chemical shifts corresponding to repeating units of BA as 
described in Example 1 and ECH of MPECH 3.6 and 3.8 ppm. The integrated 
areas indicate about 16.7 wt % of MPECH is incorporated in MCTA. Carboxyl 
content, GPC data, total chloride, and Brookfield viscosity are also 
summarized in Table IV, below (after Example 15). The total chloride of 
5.27 wt % indicates that 15.8 wt % of MPECH is incorporated in the comb. 
The data in Table IV show that the comb copolymer having pendent chains of 
a polyether can be made in as high yield as the copolymers having pendent 
chains of a polyester as made in foregoing examples. 
EXAMPLE 15 
In a manner analogous to that illustrated in the foregoing Example 1, 
hydroxyl-terminated comb copolymer (MHTA) was synthesized with BA and MPCL 
(MPCL6) at the MPCL/BA weight ratio of 15/85. The polymerization were 
carried out in acetone at 80.degree. C. with AHMP (azo initiator, hydroxyl 
functional) as an initiator. The polymerization conditions, GPC data and 
Brookfield viscosity are set forth in Table IV. The data in Table IV show 
that the comb copolymer having terminal reactive hydroxyl groups can be 
made from AHMP as the copolymers having terminal reactive carboxyl groups 
as made in foregoing examples with ADVA. 
TABLE IV 
______________________________________ 
Example 
13 14 15 
MCTA19 MCTA20 MHTA1 
______________________________________ 
Polymerization: 
Monomer: 
BA, 
g -- 384.00 408.00 
moles -- 3.00 3.18 
EHA, 
g 327.25 -- -- 
moles 1.78 -- -- 
Macromer: MPCL6 MPECH1 MPCL6 
MW 640.00 856.00 640.00 
g 57.75 96.00 92.00 
moles 0.090 0.112 0.144 
Azo initiator ADVA ADVA AHMP 
Initiator Soln: 
g, 234.00 294.50 172.40 
wt % 16.30 16.30 16.30 
neat, g 38.14 48.00 33.60 
moles 0.136 0.171 0.171 
Monomer/ADVA by wt. 
10.09 10.00 14.29 
Acetone, g 160.00 185.50 184.50 
Total, g 721.25 480.00 356.90 
background Monomer, g 
85.00 106.00 106.00 
Metered Monomer, g 
309.00 374.00 374.00 
Metering Time, hr 
4.00 4.00 4.00 
Post Pzn Time, hr 
0.50 1.00 1.00 
Total Time, hr 4.50 5.00 5.00 
Total Solids, % 
51.86 60.16 62.39 
Product, g 366.00 409 378 
Yield, % 78.04 73.10 67.79 
Heat loss, % 0.62 0.01 0.19 
Characterization: 
Carboxyl, Ephr 0.052 0.024 -- 
Acid No. 29.17 13.46 -- 
CEW 1923 4166 -- 
Total Cl, wt % -- 5.27 -- 
GPC: 
Mn .times. 10.sup.3 
-- 3.92 19.90 
Mw .times. 10.sup.3 
-- 29.20 209.00 
Mw/Mn -- 7.44 10.50 
Peak .times. 10.sup.3 
-- 13.00 84.20 
Brookfield Viscosity 
113 328 1888 
at 27.degree. C. 
cps .times. 10.sup.3 
______________________________________ 
COMATIVE EXAMPLES 16-17 
In a manner analogous to that illustrated in the foregoing Example 1, two 
comparative carboxyl-terminated homopolymer of BA and HEA synthesized in 
the absence of a macromer. The homopolymers made are straight-chain 
polymers without pendent chains. The comparison is set forth in Table V. 
TABLE V 
______________________________________ 
Example 
16 17 
CTA1 CTA2 
______________________________________ 
Polymerization: 
Monomer: 
BA, 
g 385.00 -- 
moles 3.00 -- 
EHA, 
g -- 385.00 
moles -- 2.09 
Monomer/ADVA by wt. 
10 10 
Background Monomers, g 
85.00 85.00 
Metering Monomer, g 
300.00 300.00 
Metering Time, hr 3.5 3.5 
Post Pzn Time, hr 0.5 0.5 
Total Time, hr 4.0 4.0 
Total Solids, % 58.00 52.42 
Product, g 311 362 
Yield, % 73.50 85.55 
Heat loss, % 0.64 0.75 
Characterization: 
Carboxyl, Ephr 0.055 0.037 
Acid No. 30.86 20.76 
CEW 1818 2702 
______________________________________ 
EXAMPLE 18 
In this example the functionality of MCTA comb copolymers was measured. 
Since the mol wt of a MCTA is determined by GPC, it is measured in terms 
of equivalent weight relative to standard polystyrene. A mol wt so 
determined may not be the true mol wt. A more meaningful mol wt of a MCTA 
is determined by VPO (vapor pressure osmometry) in toluene. The 
functionality was estimated from the number average mol wt Mn from VPO and 
the CEW (carboxyl equivalent weight) from carboxyl content. The results 
listed in Table VI, indicate that the MCTA copolymers have an estimated 
functionality in the range from 1.6-1.9. Since mol wts obtained from VPO 
were not corrected for the presence of antioxidant and 2-5% of oligomers 
(Mn less than 500 as determined by GPC), the numbers measured tend to be 
lower than the actual mol wt. As a result, the true functionality of a 
MCTA would be expected to be higher than an estimated value as obtained 
herein. 
TABLE VI 
______________________________________ 
Functionality of MCTA 
Polymer Fn Mn by VPO CEW 
______________________________________ 
CTA1 2.2 6655 3030 
MCTA1 1.6 4958 3030 
MCTA5 1.9 5253 2703 
MCTA6 1.6 4751 2941 
MCTA7 1.7 4816 2857 
MCTA8 1.8 4962 2857 
______________________________________ 
EXAMPLE 19 
In this example the thermo-oxidative stability of MCTA comb copolymer is 
compared with commercial CTBNX8 and CTA in an OIT (oxidative induction 
time) test by DSC (differential scanning calorimetry), similar to 
ASTM-D3895 for polyethylene, except at a temperature of 150.degree. C. and 
210.degree. C. instead of 200.degree. C. The test requires that the sample 
be heated in an inert atmosphere at a specified rate until it reaches 
150.degree. C. at which time the atmosphere is changed to oxygen. 
The sample is then held until oxidative decomposition occurs, as noted by 
the change in the DSC curve in an exothermic direction. The time taken up 
to that at which decomposition is seen, is the OIT. 
The results show that acrylic polymers of MCTA and CTA containing no 
olefinically unsaturated repeating units are more stable than CTBN 
containing unsaturated butadiene repeating units. CBTN shows an OIT of 2 
min at 150.degree. C., whereas both MCTA and CTA show an OIT in the range 
from 20-40 min, depending upon the particular components of the 
copolymers. At 210.degree. C., the test shows that MCTA is as stable as 
CTA and has an OIT in excess of 2 min. This evidence proves that the 
pendent chains of MPCL in MCTA does not impair stability of the CTA. 
EXAMPLE 20 
In this example, the miscibility of various MCTA comb polymers in DGEBA 
(n=0.03) are studied and compared with a CTA polymer and commercial CTBN 
polymers by cloud-point study. The application of cloud-point for 
miscibility studies in the CTBN--epoxy resin system has been reported by 
D. Verchere, et al., in Polymer, 30, 107 (1989). 
As in the reference study, the cloud-point was recorded when the 
transparent solution of a reactive polymer in epoxy resin becomes opaque 
when cooled at a constant rate. Below the cloud-point, the mixture is two 
phases. The cloud-points of each reactive polymer were measured by varying 
the concentration of comb in the epoxy resin. For simplicity, the maximum 
temperature (Tmax) for a cloud-point, for each reactive polymer is set 
forth in Table VII. 
The results shown in Table VII provide a scale for relative miscibility of 
various reactive polymers in epoxy resin. They also indicate the 
incorporation of macromer pendant chains into polyacrylate has made CTA 
which is normally immiscible in an epoxy resin even at elevated 
temperature in the range from about 50.degree. C. to 84.degree. C., 
miscible. Unmodified CTA is not miscible below 85.degree. C. 
Though unmodified CTA is miscible in DGEBA and forms a single phase at 
above 85.degree. C., it cause macroscopic demixing of the elastomer before 
curing or separates from the epoxy matrix prematurely during curing and 
forms elastomeric particles too large for toughening purpose because of 
unfavorable miscibility. On the other hand, commercial CTBNX8 and CTBNX13 
(which have unsaturation in the chains) with Tmax cloud-points of 
50.degree. C. and below 0.degree. C., respectively, have been shown to 
form a microphase of elastomeric particles which provide effective 
toughening. Furthermore, CTBNX13 with lower Tmax performs much better than 
CTBNX8 as a toughening agent for epoxy resins. As shown in Table VII, the 
Tmax temperatures of MCTA1 MCTA2, and MCTA5 comb copolymers are in the 
range between CTBNX8 and CTBNX13, and MCTA3 and MCTA4 comb copolymers have 
Tmax below 0.degree. C. The data also show that the miscibility increases 
as the amounts of macromer used increase. 
TABLE VII 
______________________________________ 
MPCL wt % Mn of Tmax, 
Sample in MCTA MPCL .degree.C. 
______________________________________ 
CTA 1 -- -- 85 
CTBNX8 -- -- 50 
MCTA2 10 640 33 
MCTA1 15 640 18 
MCTA3 20 640 &lt;0 
MCTA4 25 640 &lt;0 
MCTA5 15 420 13 
CTBNX13 -- -- &lt;0 
______________________________________ 
Further evidence of miscibility provided by incorporation of MPCL pendent 
chains are shown in this example, in which the miscibility of various MCTA 
comb copolymers in Derakane.RTM. 8084 is studied and compared with CTA 
polymer and commercial CTBN polymers. Derakane.RTM. 8084 is an elastomer 
modified vinyl ester resin obtained from Dow Chemical Co. In this study, a 
reactive polymer was mixed with Derakane.RTM. 8084. Then the mixture was 
poured into a 100 ml graduated cylinder and the miscibility was measured 
by the stability of the mixture in ml of separation/day. Commercial 
CTBNX8, CTBNX13, and VTBNX33 do not form a homogenous mixture with 
Derakane 8084 initially. Only commercial ETBNX40 forms homogenous 
solution, however, it is less miscible compared to MCTA4 and MCTA6 (MPCL 
modified) and MCTA20 (MPECH modified) comb copolymers of this invention. 
The reactive polymers of this invention show no phase separation for up to 
3 days. The results are set forth in Table VIII. 
TABLE VIII 
______________________________________ 
Example 
25A 25B 25C 25D 
ETBNX40 MCTA4 MCTA6 MCTA20 
______________________________________ 
Derakane .RTM. 8084 
100 100 100 100 
Reactive Polymer 
6 6 5.3 5.3 
Day: ml of Separation 
1 0 0 0 0 
2 3 0 0 0 
3 6 0 0 0 
6 8 0 5 5 
______________________________________ 
EXAMPLE 22 
Since only carboxyl (COOH), hydroxyl (OH), thio (SH) and epoxy terminal 
groups may be directly introduced on the backbone of a comb copolymer made 
with an initiator, other end groups are introduced by conversion of one of 
the foregoing directly introduced end groups. Epoxy end groups are more 
economically introduced by conversion than directly. 
In this example, META polymers are prepared by converting the terminal 
carboxyl groups on the backbone of MCTA into epoxy groups by reacting with 
Epon 828 in a ratio of (epoxy resin)/(MCTA)=3:2 by wt. At 130.degree. C., 
250 g of MCTA1 from Example 1 are reacted with 375 g of Epon 828 (epoxy 
equivalent weight 190) for 7.5 hrs under a nitrogen atmosphere in a 
three-neck flask equipped with a mechanical stirrer, a condenser, and a 
nitrogen inlet. 594 g of epoxy-terminated adduct are obtained. The METAl 
obtained from the reaction is a single phase, has a Brookfield viscosity 
of 80,600 cps at 27.degree. C., and a carboxyl content of less than 0.001 
Ephr and an epoxy equivalent weight of 338. 
DSC analysis shows that the MCTA/epoxy adduct has a single Tg of 
-27.4.degree. C. There is no Tg at -15.1.degree. C. corresponding to Epon 
828; or, at 47.degree. C. corresponding to MCTA. The single Tg indicates 
that META is miscible with end-reacted Epon resin. In a procedure 
analogous to the foregoing, the carboxyl groups of MCTA2, MCTA3, MCTA4, 
MCTA5, and MCTA6, are converted into epoxy groups by reacting with Epon 
828, as evidenced by a single Tg. 0n the other hand, ETA polymers obtained 
from comparable CTA1 (butyl acrylate homopolymer) and CTA2 (ethylhexyl 
acrylate homopolymer) with no pendent chain of PCL, made in analogous 
manner, result in a two-phase system. 
EXAMPLE 23 
In this example, MATA polymer is prepared by converting the terminal COOH 
groups on the backbone of MCTA into amino groups by reacting with 
aminoethyl piperazine at the equivalent ratio of amino/carboxyl in the 
range from 1.85 to 1.0. At 140.degree. C., 150 g of MCTA1 from Example 1 
are reacted with 12.4 gm of aminoethyl piperazine for 14 hrs under a 
nitrogen atmosphere in a three-neck flask equipped with a mechanical 
stirrer, a condenser, and a nitrogen inlet. MATA is a single phase highly 
viscous polymer and has a carboxyl content of less than 0.01 Ephr. 
EXAMPLE 24 
In this example, MVTA polymer is prepared by converting the terminal COOH 
groups on the backbone of MCTA into unsaturated vinyl groups by reacting 
with glycidyl methacrylate at the equivalent ratio of vinyl/carboxyl=1.0. 
At 110.degree. C., 60 gm of MCTA1 from Example 1 are reacted with 3 gm 
glycidyl methacrylate in a three-neck flask equipped with a mechanical 
stirrer and a condenser until the carboxyl content of the mixture below 
0.001 Ephr. 
COMATIVE EXAMPLES 25-26 AND EXAMPLES 27-30 
In these examples, MCTA (Examples 27-29) and MATA (Example 30) comb 
copolymers are evaluated as tougheners for epoxy resins, and compared with 
commercial CTBNX8 (Example 26) and the one without a toughener (Example 
25). The epoxy resin is a 50/50 by wt mixture of D.E.R.RTM. 661 
(EEW=500-560) obtained from Dow Chemical Co. and Epon.RTM. 828 
(EEW=185-192) obtained from Shell Chemical Co, both being DGEBA epoxy 
resins. The reactive modifiers are evaluated as a 3:2 epoxy adduct as made 
in Example 22. DDS (4,4'-diaminodiphenyl sulfone), which is sold 
commercially by Ciba-Geigy Co. as Hardener HT 976, was used as a curing 
agent. The recipes set forth below in Table IX were prepared in the manner 
described hereafter. 
A difunctional METAl, epoxy-terminated epoxy adduct of MCTA1 
(carboxyl-terminated comb copolymer of BA/FA at 85/15 by weight) made in 
Example 22 was mixed in a glass jar with Epon.RTM. 828 and D.E.R..RTM. 661 
at 135.degree. C., using a mechanical stirrer. DDS curing agent was then 
added to the mixture. After the mixture was degassed under vacuum, it was 
cast into an 8".times.10".times.0.25" (20 cm.times.25 cm.times.0.635 cm) 
Teflon.RTM. resin coated aluminum mold, and cured for 2 hr at 170.degree. 
C. to form plaques. In Examples 27 and 28, the cured epoxy resins contain 
10 and 15 phr of MCTA1, respectively. In a similar manner, samples of 
epoxy resin without a toughening agent and with a 3:2 epoxy adduct of 
CTBNX8 as a toughening agent, were prepared for comparative purpose as 
Comparative Examples 25 and 26, respectively. In Example 31, MATA1 
(amino-terminated comb copolymer of BA/FA at 85/15 by weight) made in 
Example 23 is evaluated at 10 phr. In Example 29, which has the same 
recipe as Example 27, is cured at multiple stages: two hours at 
135.degree. C. two hours at 180.degree. C., and two hours at 250.degree.. 
Specimens for physical testing were machined from these 0.25" plaques. The 
following physical testings were carried out in accordance with ASTM 
standards: Tensile and elongation, ASTM D-638; fracture energies using a 
compact tension specimen, ASTM E-399; Flexural, ASTM D-790; Heat 
Distortion, ASTM D-648; and Durometer Hardness "D", ASTM D-2240. Glass 
transitions (Tg) are measured using a Mettler DSC instrument. 
The results of physical testings are also set forth in Table IX. The data 
in Comparative Example 26 show about a three-fold increase in the fracture 
energy G.sub.IC after mixing an epoxy adduct of commercial CTBNX8 at 10 
phr into the unmodified mixed epoxy resins of Example 25 which is free of 
elastomer. The data in Example 28 show that the improvement of toughness 
as indicated by increasing the fracture energy of the cured resin by 
incorporating of MCTA1 of the present invention at 15 phr as an epoxy 
adduct is as good as that by incorporating CTBNX8 at 10 phr. Although the 
improvement of toughness by incorporating of MCTA1 at 10 phr in Example 27 
is not as good as that of incorporating CTBNX8, but MCTA1 at 10 phr still 
show about a two-fold increase in the fracture energy G.sub.IC. The data 
in Example 30 show that the performance of MATA1 of the present invention 
as a toughener is nearly as good as that of CTBNX8. Comparing to Example 
28, Example 29 shows that the heat distortion temperature (HDT) of cured 
epoxy resin can be significantly increased by multiple-stage curing. 
Though all elastomer-modified cured epoxy resins suffer some reduction in 
tensile strength, flexural strength, and HDT, such reduction is not 
generally sufficient to detract from their use for the purpose at hand. 
TABLE IX 
__________________________________________________________________________ 
Physical Properties of DER 661/Epon 828 with Modified CTA cured with DDS 
Comparative 
Example 
25 26 27 28 29 30 
__________________________________________________________________________ 
Elastomer: none CTBNX8 
MCTA1 
MCTA1 
MCTA1 
ATA1 
Elastomer, phr 0 10 10 15 15 10 
RECIPES FOR PLAQUES: 
DER 661 50 50 50 50 50 50 
Epon 828 50 35 35 22.5 22.5 50 
META1 epoxy adduct 
-- -- 25 37.5 37.5 -- 
ATA -- -- -- -- -- 10 
CTBN X8 epoxy adduct 
-- 25 -- -- -- -- 
DDS 24 24 24 24 24 24 
PHYSICAL PROPERTIES: 
Tensile, ASTM D-638 
Strength at Break, psi 
13865 
10830 
11120 
9939 10130 
8298 
Elongation at Break, % 
7.1 7.1 5.5 6.4 6.4 3.2 
Modulus, 1000 .times. psi 
455 369 360 326 309 392 
Flexural Test, ASTM D-790 
Strength, psi 19030 
15670 
16070 
14200 
14020 
12730 
Elongation, % 0.08 0.07 0.08 0.07 0.08 0.05 
Modulus, 1000 .times. psi 
407 344 351 313 298 313 
Fracture Test - Compact Tension, 
ASTM E-399 
K.sub.IC, MN/m3/2 
0.712 
1.229 
1.043 
1.237 
1.228 
1.183 
G.sub.IC, j/m2 159.68 
618.81 
398.27 
625.94 
648.53 
573.34 
Heat Distortion, ASTM D-256 
122 117 119 113 132 117 
.degree.C. at 264 psi 
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EXAMPLES 31-34 
In the following two examples, MCTA comb copolymers are evaluated as 
built-in tougheners by preparing elastomer-modified vinyl ester resins in 
a manner analogous to that described in U.S. Pat. No. 3,892,819 to Najvar. 
In the first step to form an epoxy adduct of MCTA, 175 gm of Epon 828, 
11.7 gm of bisphenol, and 36.1 g of MCTA1 of Example 1 were reacted in the 
presence of 0.2 ml of 70 wt % of ethyltriphenylphosphonium acetate 
solution in methanol (obtained form Alfa Corporation) as a catalyst for 3 
hr at 150.degree. C. under nitrogen in a three-neck flask equipped with a 
mechanical stirrer, a condenser, and a nitrogen inlet. At the end of the 
reaction, the carboxy content of the mixture is 0.0002 Ephr. The second 
step of the reaction was carried in the same flask by adding 66.2 g of 
methacrylic acid, 0.17 g of hydroquinone, and 0.2 ml of 70 wt % of 
ethyltriphenylphosphonium acetate solution in methanol under air at 
110.degree. C. for 6 hr. The elastomer-modified vinyl ester resin has a 
Brookfield viscosity of 2125 cps at 22.degree. C. and a carboxyl content 
of 0.0002 Ephr, which indicates the nearly complete reaction of 
methacrylic acid. After diluted with styrene monomer at 
resin/styrene=60/40 by weight, the final resin, VRE1, has 7.5 wt % of 
MCTA1 which is incorporated in the backbone of the resin and used in 
Example 32. 
In a procedure analogous to the foregoing, the omermodified vinyl ester 
resin in styrene, VER2, having 12.5 wt % of MCTA1 was prepared from 62.8 g 
of MCTA1 and used in Example 33. 
The vinyl ester resins were cured with a combination of cobalt naphthenate 
at 0.5 phr and MEK peroxide at 2.0 phr, in 8".times.10".times.0.25" (20 
cm.times.25 cm.times.0,635 cm) Teflon.RTM. resin-coated aluminum molds. 
All recipes were cured for one hour at 60.degree. C. plus two hours at 
120.degree. C., to form plaques. 
In Examples 36 and 37, VER1 and VER2 (these were modified with 7.5 wt % and 
12.5 wt % of MCTA1, respectively), were used. 
In Examples 31 and 34, Derakanes 8084 and 411 obtained from Dow Chemical Co 
was used, respectively. Derakane 411 is untoughened vinyl ester resin 
containing no omer and Derakane 8084 is an elastomer-modified vinyl ester 
resin, believed to be made in a manner analogous to that taught for VER1, 
containing 7.5 wt % of CTBNX8. 
The results of physical testings are set forth in Table X. The data in 
Example 31 of commercial Derakane 8084 show about a two-fold increase in 
the fracture energy G.sub.IC after incorporating a commercial CTBNX8 
reactive polymer at 7.5 wt % into the unmodified vinyl ester resin 
Derakane 411 of Example 34 which is free of elastomer. The data in Example 
33 show that the improvement of toughness as indicated by increasing the 
fracture energy of the cured resin by incorporating of MCTA1 of the 
present invention at 7.5 wt % is twice greater than that by incorporating 
commercial CTBNX8 as shown in Example 31 with the same elastomer content. 
The data in Example 33 show that the fracture energy is great than 1000 
j/m2 when vinyl ester is modified with 12.5 wt % of MCTA1 of the present 
invention. The tensile strength, modular, and Tg of MCTA modified cured 
vinyl ester resin are comparable with those of commercial Derakane 8084 
which is modified with CTBNX8. 
TABLE X 
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Physical Props of MCTA Mod'f'd Vinyl Ester Resins - Prereacted 
Example 
35 38 
Derakane 
36 37 Derakane 
8084 MCTA1 
MCTA1 
411 
__________________________________________________________________________ 
Elastomer, phr 7.5 7.5 12.5 0 
PHYSICAL PROPERTIES: 
Tensile, ASTM D-638 
Strength at Yield, psi 
8813 9647 8028 10507 
Elongation at Yield, % 
4.3 3.6 4.5 3.4 
Strength at Break, psi 
7883 9608 7666 10507 
Elongation at Break, % 
10.5 3.6 6.8 2.0 
Modulus, 1000 .times. psi 
407 419 388 460 
Flexural Test, ASTM D-790 
Strength, psi 13290 14830 
13930 
15530 
Elongation, % 0.06 -- 0.04 0.05 
Modulus, 1000 .times. psi 
355 385 330 432 
Fracture Test - Compact Tension, 
ASTM E-399 
K.sub.IC, MN/m3/2 
1.071 1.66 1.77 0.810 
GIc, j/m2 415 914 1216 195 
Tg by DSC, .degree.C. 
105 107 104 120 
TEM: Avg Particle size, .mu.m 
&lt;1 &lt;1 &lt;1 none 
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EXAMPLE 35 
In this example, MHTA (copolymer of butyl acrylate and macromer, with 
OH-terminated backbone) was obtained by copolymerizing BA and MPCL6 
(MW=640) at 85/15 by wt ratio with hydrogen peroxide as the free-radical 
initiator. The polymerization was carried out in a 2 L jacketed glass 
Buchi reactor. In a beverage bottle, 72 g of MPCL was dissolved in 408 g 
of BA. Then the bottle was capped and the mixed monomer solution was 
purged with nitrogen. 480 g of MEK (methyl ethyl ketone) is charged to the 
reactor which was then evacuated until the MEK boiled, and then pressured 
to 30 psig with nitrogen. This protocol was repeated three times. The 
reactor was then heated. When the reactor temperature reached 125.degree. 
C. 106 g of mixed monomer solution were added into the reactor followed by 
40 g of hydrogen peroxide (35 wt % active, grade DS35 obtained from 
Chemprox Chemical Inc.). The remaining mixed monomers were then metered 
into the reactor over 4 hours while the reactor temperature was kept at 
125.degree.-130.degree. C., at a pressure of 55 psi. After the completion 
of metering, the post polymerization was carried out for an additional 
hour with a total polymerization time of five hours. At the end of post 
polymerization, the reactor was cooled down. When the temperature was 
about 30.degree. C. and the polymer solution was blown down to a 
one-gallon jar. A total solids of 48.1% corresponding to 100% conversion 
of monomers was obtained. 
To the polymer solution 0.72 g of Irganox 1010 (antioxidant) was added. The 
polymer solution then was filtered and dried with a rotary evaporator 
under vacuum at 125.degree. C. A total of 434 g of very light yellow clear 
liquid polymer corresponding to 91% yield was obtained. Some portions of 
polymer were lost during filtration, drying, and transferring. The polymer 
has Brookfield viscosity of 6,900 cps at 27.degree. C.