Epoxy resins based on tetraglycidyl diamines

Novel tetraglycidates have the formula ##STR1## wherein R.sup.1 and R.sup.2 are independently hydrogen, alkyl of 1 to 8 carbon atoms, perfluoroalkyl, or cycloalkylidene of 5 to 7 carbon atoms. Epoxy resin systems exhibiting good tensile properties and moisture sensitivity can be made by copolymerizing the tetraglycidates with a polyamine curing agent. Prepregs can be made by combining the epoxy resin systems with a fiber reinforcement. The epoxy resin system may include a co-epoxide.

FIELD OF THE INVENTION 
This invention relates to novel bis(4,4'-aminophenoxy)-2,2-diphenylalkyl 
tetraglycidates, to epoxy resin systems made from the novel 
tetraglycidates, to prepregs made using the epoxy resin systems, and to 
articles of manufacture which incorporate the epoxy resins or the 
prepregs. 
BACKGROUND OF THE INVENTION 
Polyglycidates (also referred to herein as epoxy compounds) generally 
constitute a class of compounds having at least two glycidyl groups, the 
reactive moiety in each glycidyl group being the epoxy group. 
Many epoxy compounds are commercially available for use in epoxy resin 
systems including N,N,N',N',-tetraglycidyl-4,4'-methylene dianiline, 
having the structure 
##STR2## 
This material is made by reacting an excess of epichlorohydrin with 
methylene dianiline. It is available commercially as MY-720 from Ciba 
Geigy Corp., Ardsley, N.Y. and consists of about 70% by weight of the 
above tetraglycidate, the remainder being oligomers and triglycidates. 
Another commonly used epoxy compound is made by reacting bisphenol A with 
epichlorohydrin. Commercially available resins made from this reaction 
contain the structure 
##STR3## 
and include DER 331 from Dow Chemical and EPON.RTM. 828 (registered 
trademark) from Shell. 
Epoxy groups are reactive to amine and hydroxyl functionalities and can 
thus be copolymerized (i.e. cured) with compounds containing such 
functionalities to make epoxy resin systems. Generally polyamines are 
favored as curing agents although polyhydroxy curing agents are also well 
known. The epoxy compounds can be reacted with one or more curing agents 
such that they are crosslinked, thereby finding use as structural 
adhesives or as encapsulating materials for electronic components. 
Epoxy resin systems are often used in prepregs, ready-to-mold materials 
comprising fibrous reinforcement impregnated with uncured or partially 
cured epoxy resin systems. Prepregs can be assembled into a final part 
(such as an airplane wing) and fully cured (C-staged) to form a finished 
product. Such prepregs find wide use in the aircraft and aerospace 
industries. 
Key properties of epoxy resin systems are tensile properties and moisture 
sensitivity. High tensile strength is desirable in, for example, 
structural adhesives. Low moisture sensitivity is also desirable since it 
leads to improved performance under hot/wet conditions. 
Most advanced composites are fabricated from prepreg. Resin systems 
containing an epoxy compound such as MY-720 and aromatic amine hardener 
are often used in prepreg since they possess the balance of properties 
required for this material. State-of-the-art epoxy/carbon fiber composites 
have high compressive strengths, good fatigue characteristics, and low 
shrinkage during cure. However, since most epoxy formulations used in 
prepreg are brittle, these composites have poor impact resistance. In 
addition, epoxy formulations absorb moisture which reduces their high 
temperature properties and affects their dimensional stability. 
Thus, new epoxy compounds which could be used to make epoxy resin systems 
which improve such desirable physical and mechanical properties, relative 
to present state-of-the-art epoxy systems, would be a useful addition to 
the structural adhesive, airplane, aerospace, and other like art areas. 
THE INVENTION 
The present invention provides, in one aspect, novel tetraglycidates of the 
formula 
##STR4## 
wherein R.sup.1 and R.sup.2 are independently hydrogen, alkyl of 1 to 8, 
preferably 1 to 4, carbon atoms, or perfluoroalkyl, 
##STR5## 
taken together may also form a cycloalkylidene ring of from 5 to 7 carbon 
atoms such as cyclopentylidene, cyclohexylidene, and cycloheptylidene. 
R.sup.1 and R.sup.2 are most preferably methyl groups or trifluoromethyl 
groups. 
In another aspect the invention provides novel epoxy resin systems 
comprising a tetraglycidate having the above formula (I) copolymerized 
with a polyamine curing agent (also referred to herein as a hardener). The 
polyamine hardener may, for example, be any of the well known aliphatic 
polyamines such as diethylene triamine, triethylene tetraamine, or 
tetraethylene pentaamine. Additional hardeners are those containing 
benzenoid unsaturation such as m- and p-phenylenediamine, 
1,6-diaminonaphthalene, 4,4'-diaminodiphenylmethane (also known as 
4,4'-methylene dianiline), 4,4'-diaminodiphenyl ether, sulfanilamide, 
3-methyl-4-aminobenzamide, and 4,4'-diaminodiphenyl sulfone (DDS), 
4,4'-diaminodiphenyl, ring-alkylated derivatives of m-phenylene diamine 
such as ETHACURE.RTM.100 from Ethyl Corp., Baton Rouge, LA, and the like. 
Another useful class of polyamine curing agents are those disclosed in 
U.S. Pat. No. 4,521,583, which have the formula 
##STR6## 
wherein a is 2 or 3, R.sup.3 is hydrogen, alkyl of 1 to 8 carbon atoms or 
aryl of 6 to 18 carbon atoms, and X is a divalent or trivalent organic 
hydrocarbon, hetero-interrupted hydrocarbon, or substituted hydrocarbon 
radical or 
##STR7## 
These hardening agents may be prepared from corresponding starting 
materials, e.g. nitro compounds, by reduction, for example, according to 
methods described in U.K. Pat. No. 1,182,377. Particularly contemplated 
are those compounds (II) wherein R.sup.3 is hydrogen or C.sub.1 -C.sub.3 
alkyl and X is a divalent or trivalent radical selected from 
(1) divalent groups consisting of --(CH.sub.2).sub.y -- wherein y is an 
integer of from 2 to 12, --CH.sub.2 CH.sub.2 OCH.sub.2 CH.sub.2 OCH.sub.2 
CH.sub.2 --, 
##STR8## 
(2) trivalent groups of the formula 
##STR9## 
wherein n and m are the same or different integers from 1 to 4. 
Preferred curing agents are (i) DDS, (ii) those diamines having the formula 
##STR10## 
wherein each of the two amino groups is meta or para to the carbonyl group 
bonded to the same ring and wherein Y is 
EQU --(CH.sub.2).sub.q -- 
wherein q is an integer from 2 to 12, preferably 2 to 6, and most 
preferably 3; 
##STR11## 
wherein t is an integer of from 0 to about 5; and 
##STR12## 
The polyamine curing agent and epoxy compound are mixed essentially in an 
amount which provides about 0.3 to about 2.0, preferably about 0.4 to 1.7, 
and most preferably about 0.45 to about 1.3 moles of amine hydrogen for 
each mole of epoxy groups. The epoxy resin system comprising the curing 
agent and epoxy compound may be cured by heating between about 
200.degree.-400.degree. F. for time periods ranging between about 0.5 and 
about 12 hours. 
In another aspect, this invention provides prepregs comprising the novel 
epoxy resins described herein. Prepregs contain structural fibers. The 
structural fibers which are useful in this invention include carbon, 
graphite, glass, silicon carbide, poly(benzothiazole), 
poly(benzimidazole), poly(benzoxazole), alumina, titania, boron, and 
aromatic polyamide fibers. These fibers are characterized by a tensile 
strength of greater than 100,000 psi, a tensile modulus of greater than 
two million psi, and a decomposition temperature of greater than 
200.degree. C. The fibers may be used in the form of continuous tows (500 
to 400,000 filaments each), woven cloth, whiskers, chopped fiber or random 
mat. The preferred fibers are carbon and graphite fibers, aromatic 
polyamide fibers, such as Kevlar 49 fiber (obtained from E. I. duPont de 
Nemours, Inc., Wilmington, DE), and silicon carbide fibers. 
The epoxy resin in this invention is prepared by standard methods, such as 
that described in U.S. Pat. No. 2,951,822 and also in an article by W. T. 
Hodges et al., SAMPE Quarterly, October 1985, pages 21-25, both of which 
are incorporated herein by reference. The method entails reacting an 
aromatic diamine with a four to twenty molar excess of epichlorohydrin at 
elevated temperature, generally 50.degree. to 100.degree. C. This is 
followed by dehydrochlorination of the intermediate chlorohydrin amine 
with aqueous base. The product is then isolated by diluting with a water 
immiscible solvent, washing with water, drying with a suitable desicant, 
and concentrating to obtain a resinous product. The epoxide thus obtained 
generally is found by titration to contain 70 to 90% of the theoretical 
amount of epoxy groups. This is due to formation of oligomeric residues 
and/or incomplete reaction of the monomeric diamine with epichlorohydrin. 
For example, Kirk-Othmer Encyclopedia of Chemical Technology, 3rd edition, 
Volume 9, page 277, gives the epoxy equivalent weight (EEW) of MY-720 (a 
commonly used commercial glycidyl amine) as 117-133. The theoretical EEW 
is 105. The materials are further characterized by liquid chromatography, 
infrared spectroscopy, and nuclear magnetic resonance. 
Epoxy resin systems are prepared by heating and stirring the epoxy resin to 
60.degree. to 120.degree. C. and adding the hardener. If the hardener is a 
solid, it is preferably added as a fine powder. An inert diluent such as 
N,N-dimethyl formamide or N-methylpyrrolidone may be used if desired. 
Reaction of the epoxy and hardener occur as the mixture is heated. For 
prepreg, the mixture is B-staged or partially reacted (i.e. typically 3 to 
15 percent of the epoxy groups are reacted) in order to obtain a resin 
system with the required physical properties (i.e. viscosity and tack). 
Prepregs according to the present invention can be made by embedding 
filaments or fibers into, or by coating woven or non-woven webs, rovings, 
tows, or the like, with a curable epoxy resin resin matrix which is 
ultimately manipulated and cured to a solid composite. Particular 
selection of the filament, fiber, or textile material, epoxy compound, and 
curing agent can give a range of curable composites which can be tailored 
to suit a given need or application. 
It is preferred to apply the resin as a hot melt to the fiber 
reinforcement. The B-staged epoxy resin system may conveniently first be 
applied to long sheets of differential release paper, i.e. paper to which 
a release agent such as any of several of the silicone formulations well 
known in the art, has been applied. In a prepreg machine, resin coated on 
the release paper is transferred to a web of fiber. This is done by 
sandwiching the web between plies of coated release paper and passing the 
material through a set of heated rollers. The resulting prepreg is then 
cooled and taken up on a spool. The total amount of resin applied to the 
fiber reinforcement is preferably between about 20 and about 50 wt. 
percent of resin solids based on the weight of the uncured composite. If 
desired, the prepreg may at this point be cooled to 0.degree. F. or less 
by exposure to any convenient cryogenic material (such as dry ice) for 
shipping or storage. 
Upon rewarming to about room temperature, the prepreg can then be used to 
make structural parts such as airplane wings or fuselage components. The 
prepreg may also be used to make other useful articles such as golf 
shafts, tennis rackets, musical instruments, satellite components, and 
rocket motors. To make useful articles from prepreg the prepreg may be cut 
into strips and then laid up (e.g. on a mold surface) to create the 
desired shape. The shaped, layered composite is then fully cured at 
pressures between about atmospheric to about 500 psi and temperatures 
between about 100.degree. C. to about 300.degree. C. in an oven, 
autoclave, or heated pressure mold. Depending on the exact epoxy 
formulation, temperature, and pressure, curing times may range between 
about 0.2 and about 8 hours, the optimum time, pressure, and temperature 
being easily ascertainable by means of trial runs. This final cure 
essentially C-stages the composite, meaning that the resin has 
substantially reached the final stage of polymerization where crosslinking 
becomes general and the composite is substantially infusible. 
When making the epoxy resin system for use generally or for use 
specifically as a prepreg, a modifying thermoplastic polymer, polymer 
blend, or elastomer may be used to adjust the viscosity of the resin and 
to desirably enhance processability and mechanical properties, 
particularly toughness and damage tolerance. The classes of resins which 
are broadly useful include poly(aryl ether) resins as disclosed, for 
example, in U.S. Pat. Nos. 4,175,175 and 4,108,837 and exemplified by 
thermoplastic poly(aryl ether sulfones) available commercially under the 
registered trademark UDEL.RTM. from Union Carbide Corporation, 
polyetherimides available, for example, under the registered trademark 
ULTEM.RTM. from General Electric, phenoxy resins (of the type commercially 
available under the registered trademark UCAR.RTM. from Union Carbide 
Corporation), polyurethanes, butadiene/styrene/acrylonitrile terpolymers, 
nylons, butadiene/acrylonitrile liquid rubbers such as HYCAR.RTM. CTBN 
from B. F. Goodrich and the like. The amount of thermoplastic resin 
employed will generally fall in a range of about 1 to about 30 wt.% based 
on the weight of the epoxy resin system, although amounts above or below 
this range may be desired in certain applications. Preferred thermoplastic 
resins include poly(aryl ether sulfones), polyetherimides, phenoxy resins, 
and butadiene/acrylonitrile liquid rubbers. The thermoplastic resin is 
generally added to the epoxy compound and mixed therewith prior to 
addition of the polyamine curing agent. The modifier will often be 
miscible with the epoxy compound, although it will also often be occluded 
as a dispersion within the final cured epoxy resin once the resin is 
thermoset. 
Co-epoxides may also be used in the epoxy resin system. The co-epoxy 
compounds (or resins), when employed, may be present in an amount up to 
about 40 wt.%, preferably up to about 30 wt.%, based on the amount of 
(cured or uncured) tetraglycidate used. 
Co-epoxy compounds which may be used herein contain two or more epoxy 
groups having the following formula: 
##STR13## 
The epoxy groups can be terminal epoxy groups or internal epoxy groups. 
The epoxides are of two general types: polyglycidyl compounds or products 
derived from epoxidation of dienes or polyenes. Polyglycidyl compounds 
contain a plurality of 1,2-epoxide groups derived from the reaction of a 
polyfunctional active hydrogen containing compound with an excess of an 
epihalohydrin under basic conditions. When the active hydrogen compound is 
a polyhydric alcohol or phenol, the resulting epoxide composition contains 
glycidyl ether groups. A preferred group of polyglycidyl compounds are 
made via condensation reactions with 2,2-bis(4-hydroxyphenyl)propane, also 
known as bisphenol A, and have structures such as III, 
##STR14## 
where n has a value from about 0 to about 15. These epoxides are 
bisphenol-A epoxy resins. They are available commercially under the trade 
names such as "Epon 828," "Epon 1001", and "Epon 1009" from Shell Chemical 
Co. and as "DER 331", "DER 332", and "DER 334" from Dow Chemical Co. The 
most preferred bisphenol A epoxy resins have an "n" value between 0 and 
10. 
Polyepoxides which are polyglycidyl ethers of 4,4'-dihydroxydiphenyl 
methane, 4,4'-dihydroxydiphenyl sulfone, 4,4'-biphenol, 
4,4'-dihydroxydiphenyl sulfide, phenolphthalein, resorcinol, 
4,2'-biphenol, or tris(4-hydroxyphenyl)methane and the like, are useful in 
this invention. In addition, EPON 1031 (a tetraglycidyl derivative of 
1,1,2,2-tetrakis(hydroxyphenyl)ethane from Shell Chemical Company), and 
Apogen 101, (a methylolated bisphenol A resin from Schaefer Chemical Co.) 
may also be used. Halogenated polyglycidyl compounds such as D.E.R. 542 (a 
brominated bisphenol A epoxy resin from Dow Chemical Company) are also 
useful. Other suitable epoxy resins include polyepoxides prepared from 
polyols such as pentaerythritol, glycerol, butanediol or 
trimethylolpropane and an epihalohydrin. 
Polyglycidyl derivatives of phenol-formaldehyde novolaks such as IV where 
n=0.1 to 8 and cresol-formaldehyde novolaks such as V where n=0.1 to 8 are 
also useable. 
##STR15## 
The former are commercially available as D.E.N 431, D.E.N. 438, and D.E.N. 
485 from Dow Chemical Company. The latter are available as, for example, 
ECN 1235, ECN 1273, and ECN 1299 (obtained from Ciba-Geigy Corporation, 
Ardsley, NY). Epoxidized novolaks made from bisphenol A and formaldehyde 
such as SU-8 (obtained from Celanese Polymer Specialties Company, 
Louisville, KY) are also suitable. 
Other polyfunctional active hydrogen compounds besides phenols and alcohols 
may be used to prepare the polyglycidyl adducts useful in this invention. 
They include amines, aminoalcohols and polycarboxylic acids. 
Adducts derived from amines include N,N-diglycidyl aniline, N,N-diglycidyl 
toluidine, N,N,N',N'-tetraglycidylxylylene diamine, (i.e., VI) 
N,N,N',N'-tetraglycidyl-bis(methylamino)cyclohexane (i.e. VII), 
N,N,N',N'-tetraglycidyl-4,4'-methylene dianiline, (i.e. VIII) 
N,N,N',N'-tetraglycidyl-3,3'-diaminodiphenyl sulfone, and 
N,N'-dimethyl-N,N'-diglycidyl-4,4'-diaminodiphenyl methane. Commercially 
available resins of this type include Glyamine 135 and Glyamine 125 
(obtained from F.I.C. Corporation, San Francisco, CA.), Araldite MY-720 
(obtained from Ciba Geigy Corporation) and PGA-X and PGA-C (obtained from 
The Sherwin-Williams Co., Chicago, Ill.). 
##STR16## 
Suitable polyglycidyl adducts derived from aminoalcohols include 
O,N,N-triglycidyl-4-aminophenol, available as Araldite 0500 or Araldite 
0510 (obtained from Ciba Geigy Corporation) and 
O,N,N-triglycidyl-3-aminophenol (available as Glyamine 115 from F.I.C. 
Corporation). 
Also suitable for use herein are the glycidyl esters of carboxylic acids. 
Such glycidyl esters include, for example, diglycidyl phthalate, 
diglycidyl terephthalate, diglycidyl isophthalate, and diglycidyl adipate. 
There may also be used polyepoxides such as triglycidyl cyanurates and 
isocyanurates, N,N-diglycidyl oxamides, N,N'-diglycidyl derivatives of 
hydantoins such as "XB 2793" (obtained from Ciba Geigy Corporation), 
diglycidyl esters of cycloaliphatic dicarboxylic acids, and polyglycidyl 
thioethers of polythiols. 
Other epoxy-containing materials are copolymers of acrylic acid esters of 
glycidol such as glycidyl acrylate and glycidyl methacrylate with one or 
more copolymerizable vinyl compounds. Examples of such copolymers are 1:1 
styrene-glycidyl methacrylate, 1:1 methyl methacrylate-glycidyl acrylate 
and 62.5:24:13.5 methyl methacrylate:ethyl acrylate:glycidyl methacrylate. 
Silicone resins containing epoxy functionality, e.g., 
2,4,6,8,10-pentakis[3-(2,3-epoxypropoxy)propyl]-2,4,6,8,10-pentamethylcycl 
opentasiloxane and the diglycidyl ether of 
1,3-bis-(3-hydroxypropyl)tetramethyldisiloxane) are also useable. 
The second group of epoxy resins is prepared by epoxidation of dienes or 
polyenes. Resins of this type include bis(2,3-epoxycyclopentyl)ether, IX, 
##STR17## 
copolymers of IX with ethylene glycol which are described in U.S. Pat. No. 
3,398,102, 5(6)-glycidyl-2-(1,2-epoxyethyl)bicyclo[2.2.1]heptane, X, and 
dicyclopentadiene diepoxide. Commercial examples of these epoxides include 
vinylcyclohexene dioxide, e.g., "ERL-4206" (obtained from Union Carbide 
Corp.), 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, e.g., 
"ERL-4221" (obtained from Union Carbide Corp.), 
3,4-epoxy-6-methylcyclohexylmethyl, 3,4-epoxy-6-methylcyclohexane 
carboxylate, e.g., "ERL-4201" (obtained from Union Carbide Corp.), 
bis(3,4-epoxy-6-methylcyclohexylmethyl)adipate, e.g., "ERL-4289" (obtained 
from Union Carbide Corp.), dipentene dioxide, e.g., "ERL-4269" (obtained 
from Union Carbide Corp.) 
2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexanemetadioxane, e.g., 
"ERL-4234" (obtained from Union Carbide Corp.) and epoxidized 
poly-butadiene, e.g., "Oxiron 2001" (obtained from FMC Corp.) 
Other suitable cycloaliphatic epoxides include those described in U.S. Pat. 
Nos. 2,750,395; 2,890,194; and 3,318,822 which are incorporated herein by 
reference, and the following: 
##STR18## 
Other suitable epoxides include: 
##STR19## 
where n is 1 to 4, m is (5-n), and R is H, halogen, or C.sub.1 to C.sub.4 
alkyl. 
Reactive diluents containing one epoxide group such as t-butylphenyl 
glycidyl ether, may also be used. The reactive diluent may comprise up to 
25 percent by weight of the epoxide component. 
The preferred co-epoxy resins are bisphenol A epoxy resins of formula III 
where n is between 0 and 5, epoxidized novolak resins of formula IV and V 
where n is between 0 and 3, N,N,N',N'-tetraglycidyl xylylene diamine, and 
diglycidyl pthalate. 
The epoxy resin system may additionally contain an accelerator to increase 
the rate of cure. Accelerators which may be used herein include Lewis 
acid:amine complexes such as BF.sub.3.monoethylamine, BF.sub.3.piperdine, 
BF.sub.3.2-methylimidazole; amines, such as imidazole and its derivatives 
such as 4-ethyl-2-methylimidazole, 1-methylimidazole, 2-methylimidazole; 
N,N-dimethylbenzylamine; acid salts of tertiary amines, such as the 
p-toluene sulfonic acid:imidazole complex, salts of trifluoro methane 
sulfonic acid, such as FC-520 (obtained from 3M Company), 
organophosphonium halides, dicyandiamide, 1,1-dimethyl-3-phenyl urea 
(Fikure 62U from Fike Chemical Co.), and chlorinated derivatives of 
1,1-dimethyl-3-phenyl urea (monuron and diuron from du Pont). If used, the 
amount of cure accelerator may be from 0.02 to 10 percent of the weight of 
the epoxy resin system (i.e., epoxy plus hardener). 
In addition to structural fibers, thermoplastic polymers, and cure 
accelerators, the epoxy resin systems may also contain particulate fillers 
such as talc, mica, calcium carbonate, aluminum trihydrate, glass 
microballoons, phenolic thermospheres, pigments, dyes, and carbon black. 
In prepregs, up to half of the weight of structural fiber in the 
composition may be replaced by filler. Thixotropic agents such as fumed 
silica may also be used. 
In the epoxy resin systems (i.e. epoxy plus hardener) of this invention, 
the proportion of epoxy resin can be about 95 to about 30 percent by 
weight, preferably about 80 to about 35 wt. percent, and the proportion of 
hardener can be from about 5 to about 70 wt. percent, preferably about 15 
to about 60 wt. percent. 
In prepregs and composites (epoxy plus hardener and structural fiber), the 
percent by weight of the epoxy resin system can be from about 20 to 80 
percent by weight, based on the weight of the prepreg or composite, 
preferably about 25 to about 60 wt. percent. The structural fiber 
comprises 80 to 20 wt. percent, preferably 75 to 40 wt. percent of the 
total composition. 
The invention is further disclosed and described by means of the following 
examples which are not to be taken as limiting.

EXAMPLE 1 
This example describes the synthesis of 
4,4'-bis(4,4'-aminophenoxy)-2,2-diphenylpropane tetraglycidate (BAPPTG) 
from 4,4'-bis(4,4'-aminophenoxy)-2,2-diphenylpropane (BAPP) and 
epichlorohydrin. 
BAPP (300.0 g), epichlorohydrin (800 ml), ethanol (350 ml), and 50 ml of 
water were placed into a 2 L three-neck round-bottom flask that was 
equipped with a mechanical stirrer, addition funnel, and a thermometer 
that was connected to a Therm-o-watch temperature controller. The mixture 
was placed under a blanket of nitrogen and heated to reflux with gentle 
stirring. The reaction mixture was a slurry initially but quickly became 
homogeneous as the reflux temperature was approached. After the mixture 
had refluxed for 4 hours, the temperature was lowered to 60.degree. C. 
and 300 g of 50% aqueous sodium hydroxide were added at such a rate that 
the temperature was maintained at 60.degree. C. When addition was 
complete, the temperature was held at 60.degree. C. for 2 hours, at which 
time heating was discontinued. When the mixture was at room temperature, 
the liquid was decanted from the flask into a separatory funnel. The large 
mass of sodium chloride left behind was washed with methylene chloride 
(2.times.200 ml) and these washings were added to the separatory funnel. 
Water (500 ml) was added to the separatory funnel and the layers were 
separated. The organic phase was washed with water (2.times.300 ml) and 
brine (1.times.300 ml), dried (Na.sub.2 SO.sub.4), filtered, and the 
filtrate was concentrated on a rotary evaporator (50 mm Hg, at 80.degree. 
C., the 0.1 mm Hg at 80.degree. C.). 400 g (95%) of a light brown viscous 
liquid were obtained. Physical Data: Epoxy equivalent weight=165 g/mol 
(Theory EEW=158 g/mol). 
EXAMPLE 2 
This example describes the preparation of unreinforced castings of BAPPTG 
and a polyamine curing agent have the formula 
##STR20## 
and herein designated by the acronym DADE. 
86.0 g of the epoxy of Example 1 was heated to 100.degree. C. in a 
three-neck 500 ml round-bottom flask fitted with a thermometer connected 
to a Therm-o-watch temperature controller and a mechanical stirrer. 42.0 g 
of DADE was added. After the temperature came back to 100.degree. C., all 
the diamine dissolved after another 15-45 minutes. Vacuum (50 mm Hg) was 
applied for about 5 minutes, stirring was discontinued and the vacuum was 
applied for 5 minutes more. The resin was then poured into a mold 
(dimensions 8".times.10".times.1/8") which had been warmed in a 90.degree. 
C. oven. The casting was cured as follows: 75.degree. C. (4 
hours).fwdarw.4 hours.fwdarw.120.degree. C. (2 hours).fwdarw.2 
hours.fwdarw.179.degree. C. (2 hours). 
Glass transition temperatures were determined on a DuPont 982 thermal 
analyzer as the maximum of the loss modulus peak of a DMA scan. Water 
sensitivity was determined by soaking a 2.0".times.0.5".times.1/8" coupon 
in water for 2 weeks at 71.1.degree. C. (160.degree. F.). The percent 
weight gain of the coupon was determined after soak. 
CONTROL A 
This example is comparative and describes the preparation of unreinforced 
castings from an epoxy resin having the trade designation MY-720 and 
having as its major constituent a compound of the formula 
##STR21## 
100 g of MY-720 was placed in a three-neck round-bottom flask equipped with 
a mechanical stirrer, thermometer fitted with a Therm-o-watch temperature 
controller, and a gas adaptor. The epoxy was warmed to 110.degree. C., at 
which time 61 g of DADE were added. Heating was continued until the DADE 
was completely dissolved. Vacuum (50 mm Hg) was applied, and after 5 
minutes stirring was stopped, the heating mantle was removed, and the 
vacuum was continued 5 more minutes. The resin was poured into a 
8".times.10".times.1/8" mold that was prewarmed in a 100.degree. C. oven. 
Table I lists physical data for the castings of Example 2 and Control A. 
TABLE I 
______________________________________ 
PROPERTIES OF UNREINFORCED CASTINGS 
Example 2 Control A 
______________________________________ 
Composition.sup.a 
BAPPTG 86.0 g MY-720 100 g 
DADE 42.0 g DADE 61 g 
Tensile Properties.sup.c 
Tensile Strength 
14.5 10.5 
(ksi) 
Tensile Modulus 
498 404 
(ksi) 
Elongation (%) 
5.0 3.8 
Tg (.degree.C.) Dry 
188 210 
Wet.sup.b 155 173 
Water Uptake (%).sup.b 
2.3 3.4 
______________________________________ 
.sup.a NH/epoxide stoichiometry = 1.0/1.0 
.sup.b Measured after soaking in water for two weeks at 71.1.degree. C. 
(160.degree. F.). 
.sup.c ASTM D638 
It is apparent that compositions according to the invention have superior 
tensile strength, tensile modulus, elongation, and water resistance 
compared to Control A. 
EXAMPLE 3 
This example describes the preparation of a thermosetting composition of 
BAPPTG, 4,4' diaminodiphenylsulfone (DDS), and a reactive diluent. 
37 g of DDS was added slowly to 40 g of diglycidylphthalate (GlyCel A 100 
from Celanese Corp.), at 100.degree. C., with stirring. The mixture was 
stirred at 100.degree. C. for 1 hour, after which time 160 g of BAPPTG 
were slowly added. When the resin was homogeneous, an unreinforced casting 
was prepared in the same manner as described in Example 2. The NH/epoxide 
stoichiometry was 0.5. This casting was tested for tensile strength, 
modulus, and % elongation. Results are shown in Table II. 
TABLE II 
______________________________________ 
Example 3 
BAPPTG-160 g 
Casting Gly-Cel A 100-40 g 
Composition DDS - 37 g 
______________________________________ 
Tensile Properties 
4.3 
Tensile strength (ksi) 
Tensile modulus (ksi) 
566 
Elongation (%) 0.8 
______________________________________ 
CONTROL B 
A thermoset resin was prepared as in Example 3 with 40 g of Glycel A 100, 
48 g DDS, and 160 g of MY-720. This resin has the same NH/epoxide 
stoichiometry and weight ratio of epoxies as that of Example 3. An 
unreinforced casting prepared as in Control A was too brittle to test. 
EXAMPLE 4 
This example describes the preparation of unreinforced castings of BAPPTG, 
MY-720, and 4,4-diaminodiphenylsulfone. 
75 g of the epoxy of example 1 and 75 g of MY-720 were heated to 
100.degree. C. in a 3-neck round bottom flask equipped with a paddle 
stirrer, and a thermometer connected to a therm-o-watch temperature 
controller. 35 g of DDS was slowly added with stirring. After the mixture 
had been heated for 90 minutes at 100.degree. C., the diamine had 
dissolved. Then the resin was degassed and poured into a mold 
(8".times.10".times.1/8"). The casting was cured in the same manner as 
Example 2. 
CONTROL C 
This example is comparative and describes the preparation of an 
unreinforced casting of only M-720 and DDS. 
A resin system containing 130 g of MY-720 and 35 g DDS was prepared and 
cured as in Example 4. 
Table III lists the physical data for Example 4 and Control C. 
TABLE III 
______________________________________ 
PROPERTIES OF UNREINFORCED CASTINGS 
Example 4 Control C 
______________________________________ 
Composition BAPPTG 75 g MY-720 130 g 
MY-720 75 g 
DDS 35 g DDS 35 g 
Tensile Properties.sup.a 
Tensile Strength 
4.7 4.5 
(ksi) 
Tensile Modulus 
472 454 
(ksi) 
Elongation (%) 
1.0 1.0 
______________________________________ 
.sup.a ASTM D638 
EXAMPLE 5 
This example describes the preparation of undirectional epoxy/graphite 
prepreg. 
A thermosetting composition like that of Example 2 was prepared by blending 
1500 g of BAPPTG (EEW=175) and 672 g of the diamine DADE at 100.degree. C. 
for approximately 90 minutes. At this point a 1.5 mil film was cast and 
was determined to have appropriate tack for prepreg. It was coated on 13.5 
inch wide release paper (type 2-60-SF-157 and 168A, obtained from Daubert 
Coated Products Dixon, IL) at a coating weight of 110 g/m.sup.2. 
Twelve-inch wide undirectional prepreg tape was made by forming a ribbon of 
78 tows of carbon fiber and contacting it between 2 plies of epoxy-coated 
release paper in a prepreg machine. In the prepreg machine, the sandwich 
of fiber and coated release paper passed over a series of heated rollers 
to melt the resin into the fibers. The finished tape contained about 64 
percent by weight of fiber. Its thickness was about 0.007 inches. The 
fiber was a polyacrylonitrile-based fiber with a tensile strength of 
5.5.times.10.sup.5 psi and a tensile modulus of 35.times.10.sup.6 psi. 
CONTROL D 
This example is comparative and describes the preparation of unidirectional 
epoxy/graphite prepreg. 
A thermosetting composition like that of Control A was prepared by blending 
1227 g of MY-720 and 773 g of DADE. The resin was advanced by heating for 
100 minutes at 100.degree. C. After the mixture cooled to 70.degree. C., 
it was coated on 13.5 inch wide release paper (type 2-60-SF-157 and 168A, 
obtained from Daubert Coated Products Dixon, IL) at a coating weight of 
104 g/m.sup.2. 
Twelve-inch wide undirectional prepreg tape was made by forming a ribbon of 
78 tows of carbon fiber and contacting it between 2 plies of epoxy-coated 
release paper in a prepreg machine. In the prepreg machine, the sandwich 
of fiber and coated release paper passed over a series of heated rollers 
to melt the resin into the fibers. The finished tape contained about 70 
percent by weight of fiber. Its thickness was about 0.007 inches. The 
fiber was a polyacrylonitrile-based fiber with a tensile strength of 
5.5.times.10.sup.5 psi and a tensile modulus of 35.times.10.sup.6 psi. 
EXAMPLE 6 
This example describes the cured unidirectional laminates made from the 
prepreg of Example 5. 
The laminate was cured in an autoclave at 355.degree. F. for 2 hours. The 
autoclave pressure was 90 psi. Seven plies of prepreg were used to make 
the specimen. Compressive properties were measured using a modified 
ASTM-D695 procedure. Unidirectional graphite/epoxy tabs were added to 
prevent the sample ends from crushing. A gage length of approximately 
0.188 inches was used. End tabs on compressive samples were adhered using 
FM-300 film adhesive (obtained from American Cyanamid Company, Havre de 
Grace, MD) which was cured at 177.degree. C. for 1 hour. The longitudinal 
compressive strengths of unidirectional laminates of Example 6 is shown in 
Table IV. 
TABLE IV 
______________________________________ 
LONGITUDINAL COMPRESSIVE STRENGTH (ksi) 
ROOM 180.degree. F. 
180.degree. F. 
CONDITION TEMPERATURE (DRY) 
(DRY) (WET).sup.a 
______________________________________ 
EXAMPLE 6 215 197 185 
______________________________________ 
.sup.a Specimens were soaked in water 2 weeks at 160.degree. F. prior to 
testing. 
For many applications a longitudinal compressive strength of at least 150 
ksi is required. The results in Table IV indicate that the compositions of 
this invention possess excellent compressive strengths even under hot/wet 
conditions. 
EXAMPLE 7 AND CONTROL E 
This example demonstrates the compressive strength after impact of a 
quasiisotropic laminate fabricated with the composition of this invention, 
a prepreg prepared as in Example 5, and with a control made with prepreg 
prepared as in control D. The test employed measures the damage tolerance 
of composites. The latter depends on the choice of matrix resin. Test 
specimens had dimensions of 6.times.4.times.approximately 0.2 inches. The 
panels were impacted in the center with a Gardner type Impact Tester 
(Gardner Laboratories, Bethesda, MD) having a 5/8 inch diameter spherical 
indenter. The impact was normal to the plane of the fibers. When impacted, 
the laminate was simply supported over a 3 inch by 5 inch cut out in an 
aluminum plate with a plywood backup. The impacted panel was tested for 
residual compressive strength in a steel fixture that constrained the 
edges from out-of-plane buckling. Results are tabulated in Table V. 
TABLE V 
______________________________________ 
RESIDUAL COMPRESSIVE STRENGTH (in ksi psi) 
AFTER IMT RESULTS.sup.a,b 
EXAMPLE 7 CONTROL E 
______________________________________ 
27.2 19.3 
______________________________________ 
.sup.a Cure schedule: 2 hours at 355.degree. F. Autoclave pressure 90 psi 
Layup: [+45/90/-45/0]3S 
.sup.b IMT LEVEL 1500 INLB/IN 
It is clear that the residual compressive strength of a laminate made with 
the composition of this invention is significantly higher than that of the 
control. Thus, the fiber reinforced composites of this invention have 
improved impact resistance. 
Although only a few exemplary embodiments of this invention have been 
described in detail above, those skilled in the art will readily 
appreciate that many modifications are possible in the exemplary 
embodiments without materially departing from the novel teachings and 
advantages of this invention. Accordingly, all such modifications are 
intended to be included within the scope of this invention as defined in 
the following claims.