CA2099230A1

CA2099230A1 - High modulus epoxy resin systems

Info

Publication number: CA2099230A1
Application number: CA 2099230
Authority: CA
Inventors: Hugh C. Gardner; Michael J. Michno, Jr.
Original assignee: Individual
Current assignee: MICHNO MICHAEL J
Priority date: 1993-06-25
Filing date: 1993-06-25
Publication date: 1993-07-25

Abstract

ABSTRACT
Compositions comprising a cycloaliphatic epoxy resin and the adduct of these epoxy resins with an aromatic active hydrogen compound.

94,285

Description

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HIGH ~ODULUS EPOXY
RESIN SYSTEMS
BACKGROUND OF THE INVENTION
Advanced composites are high strength. high modulus materials which are finding increasing use as structural components in aircraft, automotive.
and sporting goods application6. Typically they comprise structural fiberc such as carbon fiber~ in the form of woven cloth or continuous filaments embedded in a thermosetting resin matrix.
Composite properties depend on bot~ the matrix resin and the reinforcement. In unidirectional carbon fiber composites, important mechanical properties include longitudinal tensile strength and modulus, transverse tensile strengt~
and modulus, and longitudinal compres6ive strength.
The matrix affects all of thece pro~erties, but has the ~reatest effect on compressive strength and transverse tensile properties. High composite compre~sive strengths and transver6e tensile moduli require that the matrix have a high modulus.
State-of-the-art epoxy matrix re6in systems in advanced composites are typically based on N,N,N',N'-tetraglycidyl 4,4'-diaminodiphenyl methane and 4,4'-diaminodiphenyl ~ulfone. These resins produce unreinforced castings which have tensile ~trengths of abou~ ~,000 psi and tensile moduli of 500,000 to 550,000 ~si. Unidirectional composites oontaining 60 volu~e fraction carbon fiber made with these matrix resins typically have transverse ten~ile strengths of 5,000 to 7,000 p~i and transverse tensile moduli of 1.0 t l.q million - 2 - ~ 3~

psi. Higher transverse p~operties are particularly desirable for applications such as pres6ure vessels. Improved compre6sive propertie6 are desirable for structures subjected to high compressive loads such as 6ucker rods for oil wells.
Epoxy resin systems aording higher matrix properties than state-of-the-art formulations are known. For example, U.S. Patent 3,398,102 discloses tacky, curable polymers formed by reacting bis(2,3-epoxycyclopentyl)ether with aliphatic polyols. Castings made by curinq tbese compositions with aromaeic amines have some of the highest tensile strengths (16 to lB,OOO psi) and tensile moduli (700 to 850,000 psi) of any thermosetting material. However, these castings typically have relatively low heat deflection temperatures and ab60rb large amounts of moisture. In addition, they cure relatively ~lowly, limiting their utility in certain composite fabrication processes such as filament winding. Thus, there is a need for matrix rs6ins which afford high tensile strengths and moduli in combination with improved heat deflection temperatures, faster cure rates, and a reduced tendency to absorb moisture.
It has now been found that compositions containing a select class of cycloaliphatic epoxides in combination with reaction products of aromatic active hydrogen containing compounds with these same cycloaliphatic epoxide6 afford unreinforced cast ngs with higher heat deflection temperatures, faster cure rates and lower water uptake than similar compo~itions containing epoxy adducts made from aliphatic polyol6.

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Further, it has been found that a particular combination of a cycloaliphatic epoxy resin with the reaction product of such cycloaliphatic epoxy resin and an aromatic active hydrogen containing compound can be used to produce unreinforced castings which have higher tensile modulii than a casting produced using the cycloaliphatic epoxide alone.
THE INVENTION
T~is invention is directed to a resinous composition comprising:
(a~ a cycloaliphatic epoxy resin selected from bis~2,3-epoxycyclopentyl) ether, 4-(1,2-epoxyethyl)-l,Z-epoxycyclohexane, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, 2-(3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy)cyclohexane meta-dioxane, bis(3,4-epoxycyclohexyl) ether, 1,4-cyclohexadiene diepoxide, a diepoxide of vinyl cyclopentenyl ether, a diepoxide of allyl cyclopentenyl ether, or mixtures thereof, and (b) t~e adduct of an epoxy resin of (a) with an aromatic active hydrogen containing compound selected from one or more of the following:
OH t~) ( i, ~ H2 ~ NH2 ~3 R R R
wherein R is H or lower alkyl, p i~ an integer of 2 or 3, or ~ R, 2 ) c ~ R2 ) c (ii) Z ~ Rl~--wherein Rl is a direct bond, O, S02, S, CO, SO, alkylidene of 1 to 6 carbon atoms, R2 i~
independently hydrogen, halogen, lower alkyl, c is an integer of O to 4, Z is OH or NHR3 and R3 is hydrogen or lower alkyl of 1 to 4 carbon atoms, and wherein the total epoxy equivalent weight of the composition is between about 60 and about 250 grams/mole.
The composition may be cured with an epoxy curing agent. Optionally, the composition may contain a thermoplastic polymer and/or a ~tructural fiber.
The preferred epoxy resins are bis(2,3-epoxycyclopentyl)ether, 4-(1,2-epoxyethyl)-1,2-epoxycyclohexane (alsc identified as vinyl cyclohexene diepoxide), 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate, 1,4-cyclohexadiene diepoxide and 2-(3,4-epoxycyclohexyl-5,5-spiro-3,~-epoxy)-cyclohexane meta-dioxane.
Of course, it is known that several of the epoxy resins of this invention exist in isomeric forms.
The compositions of this invention are cured with conventional epoxy curing agents such as aromatic diamines, aliphatic amines, anhydrides or dicyandiamide. Examples Oe aromatic diamines include 4,4'-diaminodiphenyl ether, 4,4~-diaminodiphenyl methane, 3,3'-diaminodiphenyl methane, 4,4~-diaminodiphenyl sulfone, 3,3~-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, diethyltoluenediamine, 5 ~ ~ r~ 3 ~

m-phenylenediamine, p-phenylenediamine, 4,g'-diaminodiphenyl pribpane, 4,q'-diaminodiphenyl sulfide, 1,4-bis(p-aminophenoxy)benzene, 1,4-bis(m-a~inophenoxy)~enzene, 1,3-bis-(m-aminophenoxy)benzene, 1,3-bis(p-aminophenoxy)benzene, ~,9'-bis(3-aminophenoxy)diphenyl sulfone, trimethylene gly~ol di-4-aminobenzoate, and 2,2-bis(4-aminophenoxyphenyl)propane; aliphatic a~ines include p-methane diamine and 1,6-hexanotiamine; anhydrides include tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, methyl nadic anhydride and benzophenone dianhydride.
The comeositions of this invention are resinou6, that is, they are liquids, semi-solids, or supercooled liquids at room temperature ~25C).
Their viscosities at 25C range between 5 and 5,000,000 centipoise.
Coepoxy resins which may be used in the composition of this invention contain two or more epoxy group6 having the following formula:

C/--~
_ The epoxy groups can be terminal epoxy groups or internal epoxy groups. The epoxides are of two general types: polyglycidyl compound6 or products derived from epoxidation of dienes or polyenes.
Polyglycidyl compounds contain a plurality of - 6 - ~ à~ ~

1,2-epoxide groups deriv~d 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 resin contains glycidyl ether groues. 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 structure~ such as II:

H C - CH CH2- O ~ I ~ O ~ ~H2 CH - CH2 O ~ CClH ~ ~ CH2- CH\ / H2 where n has a value from about O to about 15. These epoxides are bisphenol-A epoxy resin~. They are available commercially under the trade names such as "EPON 82fl," "EPON 1001", and ~'EPON 1009" from Shell Chemical Co., and as "DER 331", and "DER 334" from Do~ Chemical Co. The most preferred bisphenol A
epoxy resins have an "n" value between O 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.

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In addition, EPON lO~ tetraglycidyl deri~ative of 1,1,2,2-tetrakis(hydroxyphenyl)ethane from Shell Chemical Company), and Apogen 101, (a methylolated bispbenol A resin from Schaefer Chemical Co.) may also be used. Halogenated polyglycidyl compounds such as D.E.R. 580 (a brominated bisphenol A epoxy resin from Dow Chemical Company) are also useful.
Other suitable epoxy resins include polyepoxides prepared from polyols uch as pentaerythritol, glycerol, butanediol or trimethylolpropane and an epihalohydrin.
Polyglycidyl derivatives of phenol-formaldehyde novolaks ~uch as III where d =
0.1 to 8 and cresol-formaldehyde novolaks such as IV
where d = 0.1 to 8 are also useable.

~R4 III R4 = H
IV R9 = CH3 The former are commercially available as D.E.N 431, D.E.N. 438, and D.E.N. 985 from Dow C~emical Company. The latter are available as, for example.
ECN 1235, ECN 1273, and ECN 1299 (obtained from Ciba-Geigy Corporation, Ardsley, NY). Other epoxidized novolaks such as SU-8 (obtained from Celanese Polymer Specialties Company, Louisville, KY) are al~o suitable.
Other polyfunctional active hydrogen compounds besides phenols and alcohols may be used - 8 ~

to prepare the polyglyci~yl adducts of t~is inven~ion. They include amines, aminoalcohols and polycarboxylic a~ids.
Adducts derived from amines include N,N-diglycidyl aniline, N,N-diglycidyl toluidine, N,N,N',N'-tetraglyoidylxylylene diamine, (i.e., V) N,N,N',N'-tetraglycidyl-bi~ (methylamino) cyclohexane ti.e. VI) , N,N,N',N'-tetraglycidyl4,4'-diaminodipbenyl methane, (i.e. VII) N,N,NI,Nl-tetraglycidyl-3,3'-diaminodiphenyl sulfone, and N,NI-dimethyl-N,N'-diglycidyl 4,4'-diaminodiphenyl methane. Commercially available resins of this type in~lude Glyamine 135 and Glyamine 125 (obtained from F.I.C. Corporation, San Francisco, CA.), Araldite MY-720 (obtained from Ciba Geigy Corporation, Ardsley, N.Y.) and PGA-~ and PGA-C (obtained from The Sherwin-William~ Co., Chicago, Illinoi~).
/ ~2 C~ CH2 --CH2 CB~ ~C~32 O

HZ

CH2--CH~ f H2 - o -~ CH2 C~r~ C~2 CH2 N'~
~2 C~ ~ CN2 ~2 C~ CH2 C~2 C~ ~ ~ C~2 ~rs P~

CH2- CH-CH2 \ CH2-C~ H2 ' O /
VII

Suitable polyglycidyl adducts derived from aminoalcohols include 0,N,N-triglycidyl-4-aminophenol, available as Araldite 0500 or Araldite 0510 (obtained from Ciba Geigy Corporation) and 0,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 "~B 2793" (obtained from Ciba Geigy Corporation), diglycidyl ester6 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 sucb 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 resin~ containing epoxy Eunctionality, e.g., 2,4,6,8,10-pentakis t3-(2.3-ePoxypropoxy)propyl~-2~4~6~8~lo-penta~ne clopentasiloxane and the diglycidyl ether of 1,3-bis-(3-hydroxypropyl)tetramethyldisiloxane) are also useable.
The second group of coepoxy resins is prepared by epoxidation of dienes or polyenes.
Resins of this type include diglycidyl ether, VIII, ~0~ ~0~
VIII I~
reaction produc~s of bis(2,3-epoxycyclopentyl) ether with ethylene glycol whi~h are described in U.S.
Patent 3,398,10Z, 5(6)-glycidyl-2-(1,2-epoxyethyl)bicyclot2.2.1]

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beptane, IX, and dicyc~lopentadiene diepoxide.
- Commercial example~ of these coepoxides include bis(3,4-epoxycyclohexylmethyl) adipate, e.g., "ERL-4299~ (obtained from Union Carbide Corp.), dipentene dioxide, e.g., "ERL-4269" (obtained from Union Carbide Corp.) and epoxidized poly-butadiene, e.g., "Oxiron 2001" (obtained from FMC Corp.) Other suitable cycloaliphatic coepoxides include those de6cribed in U.S. Patent6 2,750,395:
2,890,194: and 3,318,~22 which are incorporated herein by reference, and the following:

O /
~C- - O~
_l ,; ~ C--O~
~

Other suitable coepoxides include:

f~ , /\
~)e ~)e where e i6 1 to 4, m is (5-e), and R5 is H, halogen, or Cl to C4 alkyl.
Reactive diluents containing one epoxide group ~uch as t-butylphenyl glycidyl ether, may also - 12 - ~ 3~

be used. The reacti~ei~diluent may comprise up to 25 percent by weight of the epoxide component.
The preferred coepoxy resins are bi6phenol A epoxy re~ins of formula II where n is between 0 and 5, epoxidized noYolak resin6 of formula III and I~ where d is between 0 and 3, N,N,N',N'-tetraglycidyl xylylenediamine, and N,N,N~,N'-tetraglycidyl 4,4~-diaminodiphenyl methane.
Up to 30 percent by weight of the composition of this invention may be a coepoxide.
The compositions of this invention may optionally contain a thermoplastic polymer. These materials have beneficial effects on the viscosity and film strength characteristics of the epoxy/hardener mixture (i.e., components a and b plus the hardener).
The thermoplastic polymers used in this invention include polyarylethers of formula ~ which are described in U.S. Paeents q,108,837 and 4,175,175, ~O-R6 _o-R7~f wherein R6 is a residuum of a dihydric phenol such as bisphenol A, hydroguinone, resorcinol, 4,4-biphenol, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3' 5,5'-tetramethyldiphenyl sulfide, 4,4'-dihydroxy-3,3',5,5'-tetramethyldiphenyl sulfone and the like. R7 is a residuum of a benzenoid compound susceptible to nucleophilic aromatic ~ubstitution reactions such as 4,4'-dichlorodiphenyl sulfone, 4,~'-difluorobenzophen~ne, and the like. The average value of f is from about 8 to about 120.
These polymers may have terminal groups whiob react with epoxy resins, such as hydroxyl or carboxyl, or terminal groups which do not react.
Other suitable polyarylethers are described in U.S. Patent 3,332,209.
Also suitable are polyhydroxyethers of Eormula XI.
R6 - - CH2 - CH - CH ~-OH
~ I
where R6 has the same meaning as fo~ Formula X and the average value of g is between about 8 and about 300; and polycarbonates 6ush as those based on bisphenol A, tetramethyl bisphenol A, 4,4'-dihydroxydiphenyl sulfone, 4,4'-dihydroxy-3,3',5,5'-tetramethyldiphenyl sulfone, hydroquinone, resorcinol, 4,4'-dihydroxy-3,3l,5,5'-tetramethyldiphenyl sulfide, 4,4'biphenol, 4,4'-dihydroxydiphenyl sulfide, phenolphthalein, 2,2,4,4-tetramethyl-1.3-cyclobutane diol, and the like. Other suitable thermoplastics include poly (t-caprolactone);
polybutadiene; polybutadiene/acrylonitrile copolymers, including those optionally containing amine, carboxyl, hydroxy, or -SH groups: polyesters, such as poly(butylene terephthalate); poly(ethylene terephthalate); polyetherimides such as the Ultem resins (obtained from the General Electric Company);
acrylonitrile/ butadiene~styrene terpolymerc, $ ~ ~ ~
lg polyamides such as nylon 6, nyloD 6,6, nylon 6,12, and Trogamid T (obtained from Dynamit Nobel Corporation); poly(amide imides) such as Torlon poly(amide imide) (obtained from Amoco Chemical Corporation, Napierville, IL): polyolefins, polyethylene oxide: poly(butyl methacrylate);
impact-modified polys~yrene; sulfonated polyethylene; polyaryla~es such as those derived from bisphenol A and isophthalic and terephthalic acid; poly(2,6- dimetbyl phenylene oxide): polyvinyl chloride and its copolymers: polyacetals;
polyphenylene sulfide and the like.
The composition may additionally contain an accelerator to increase the rate of cure.
Accelerators which may be used herein include Lewis acid:amine complexes such as BF3.monoethylamine, BF3.piperdine, BF3.2-methylimidazole; amines, such as imidazole and its derivatives such as 4-ethyl-2-methylimidazole, l-methylimidazole, and 2-methylimidazole; N,N-dimethylbenzylamine: acid salts of tertiary amines, such as the e-toluene sulfonic acid:imidazole complex, salts of trifluoro methane sulfonic acid~ such as FC-520 ~o~tained from 3M Company), and organophosphonium halides.
Phenolic compounds such as p-chlorophenol, 4,4~-dihydroxydiphenyl sulfone, bisphenoi A, and tetrachlorobisphenol A may also be used.
In some cases accelerators may be used without typical epoxids curing agents such as diamines or anhydrides. Such curing agents are, for example, the BF3-monoethylamine complex.

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The accelerators are typically used i~
amounts of from 0.1 to about 3.0 percent ba~ed on the total weight of the epoxy component of the co~position.
The structural fiber6 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 modulu6 of greater than two million psi, and a decomposition temperature of greater than 200C. The fibers may be used in the form of continuous tow~ (1000 to 400,000 filaments each), woven cloth, whiskers, chopped fiber or random mat. The preferred fibers are carbon fibers, aromatic polyamide fibers, such as Kevlar 49 fiber ~obtained from E.I. duPont de Nemours, Inc., Wilmington, DE), and silicon carbide fibers.
The composition of this invention contains from about 30 to about 98, preferably from about 35 to about 90 percent by weight of the cycloaliphatic epoxy resin (component(a)) and from about 2 to about 98, preferably from about 5 to about 85 percent by weight of the adduct of the epoxy resin and aromatic active hydrogen containing compound (component(b)).
If used, the epoxy curing agent may comprise between 2 and about 70 percent by weight of the total composition. The thermoplastic polymer may be used in amounts of up to 20 percent by weight of the total composition. The structural fiber may be used _ 16 - ~99~3~

in amounts of up to about 85, preferably from about 20 to about 80 percent by weight of the total composite.
Preimpregnated reinforcement may be made from the compositions of this invention by combining the epoxy resin (i.e., components a and b), hardener, and optionally thermoplastic polymer with the structural fiber.
Preimpregnated reinforcement may be prepared by several techniques known in the art, such as wet winding or hot melt, In the hot melt process partially advanced resin mixtures are coated as a thin film onto a silicone coated release paper. Prepreg is made by passing a ribbon of fiber through a prepreg machine between two layers of coated release paper, wbere under the action of heat and pressure, t~e resin mixture is transferred from the paper to the fibers. Prepreg made by this process is typically taken up on a spool. It is used within a few days or may be stored for months at 0F.
During prepreg manufacture, the resin sys~em ~B-stages~, or partially advances.
Composites may be prepared by curing preimpregnated reinforcement using heat and pressure. Vacuum bag/autoclave ~ures work well with these compo6itions. Laminates may al~o be prepared via wet layup followed by compression molding, resin eransfer molding, or by re~in injection, as described in European Patent ~pplication 0019149 published November 26, 1980. Typical cure temperatures are from abou~ 100F to about 500F, preferably from about 180F to about 450~F.

- 17 ~ 9~30 The compositions of this invention may be used for filament winding. In this composite fabrication process, continuous reinforcement in the form of tape or tow--either previously impregnated with resin or impregnated durinq winding--is placed over a rotating and removable form or mandrel in a preYious}y determined pattern. Generally the shape is a surface of revolution and contains end closures. When the proper number of layer~ are applied, the wound form is cured in an oven or autoclave and the mand~el removed.
The compositions of tbis invention may be used as aircraft parts ~uch as wing skins, wing-to-body fairings, floor panels, flaps, radomes;
as automotive parts such as driveshafts, bumpers, and springs; and as pressure vessels, tanks and pipes. They are also suitable for sporting goods applications such as golf shafts, tennis rackets, and fishing rods, In addition to structural fibers, the composition may also contain particulate fillers such as talc, mica, calcium carbonate, aluminum trihydrate, glass microballoons, phenolic thermospheres, and carbon black. Up to half of the weight structural fibers in the composition may be replaced by filler. Thixotropic agents such a~
fumed silica may also be used.
Further, the compositions may be used in adhesives, potting and en~apsulation, and coating applications.
E~AMPLES
The following examples serve to give specific illu~tration~ of the practice of this invention but they are not intended in any way to limit the scope of this invention.
Epoxy equivalent weights (EEW) were measured by two methods. In the first, samples were -dissolved in a 50/50 (volume) chlorobenzene/acetic acid solution and titrated with a solution of hydrogen bromide in acetic acid. In the second method, samples were dissolved in a 0.2 M solution of tetraethylammonium bromide in a 56/44 (volume) chlorobenzene/acetic acid solution and titrated with 0.1 N perchloric acid in acetic acid using crystal violet a~ an end point indicator.
Examples 1 through 6 describe the preparation of compositions of this invention.
Control A describes the preparation of a similar resin made with an aliphatic polyol.
F.XAMPL~ 1 A two-liter, 3-necked flask eguipped with a paddle stirrer, thermometer with Therm-0-Watch controller, nitrogen inlet and outlet and an electric heating mantle was charged with 700 9 of molten bis(2,3-epoxycyclopentyl) ether and 165 9 of hydroquinone. The mixture was heated to a temperature of 80C. After 11.5 ml of N,N-dimethylbenzylamine was added, the mixture was heated to 125C and held at that temperature for two hours. It was then cooled to a temperature of 115C
and maintained at that temperature for an additional hour. After the mixture was diluted with 5 kg of metbylene chloride, it was washed with 3 liters of dilute aqueous sodium chloride solution in a Morton fla~k. The clear bottom layer was separated and - 19 ~ f) ~ o washed two more times w~th 3 liter portions of distilled water; The w~shed solution was fed to a 3-liter, 3-necked flask eguipped with a paddle stirrer and a water-cooled distillation head.
Methyl~ne chloride was distilled from the mixture--first at atmospheric eressure for six hours, and then under vacuum (27 inches of mercury) for 2.5 hours. During distillation the flask was in an oil bath at a temperature of 85C. The final pot residue contained oligomers of hydroquinone and bis(2,3-epoxycyclopentyl) ether as well as unreacted bi6(2,3-epoxcyclopentyl) ether. It had an epoxy equivalent weight of 171 g/mole. Its viscosity was 39,000 centipoise at 50C. Gas chromatographic analysis indicated that the product contained 37 percent by wsight of bis(2,3-epoxycyclopentyl) ether. The yield was 630 g.

A two-liter, 3-necked Elask equipped as in Example 1 was charged with 900 g of molten bis(2,3-epoxycyclopentyl) ether and 212 g of resorcinol.
The mixture was heated to a temperature of 80C and 14.7 ml of N,N- dimethylbenzylamihe was added. The temperature of the mixture was raised to 125-128C.
It was maintained at that temperature for 7 hours.
Then it was cooled to a temperature of 105C and poured into 4000 g of methyle~e chloride in a Morton flas~ equipped with a paddle stirrer. The solution was washed five times with 3 liter portions of distilled water and then stripped of methylene chloride as in Example 1. The product (i.e., the pot residue) weighed 971 g and had an epoxy - 20 ~

equivalent weight of 2~g/mole. Its viscosity was }00,000 centipoises at 65C. The bis(2,3-epoxycyclopentyl) ether content of the resin was 24 percent by weight.
E~AMPL~ 3 A 3-liter, ~-necked flask equipped as in Example 1 was charged with 1656 g of molten bis(2,3-epoxycyclopentyl) ether and 198 9 of resorcinol.
The mixture was heated to a temperature of glC and then treated with 15 ml of N,N-dimethylbenzylamine.
During the next 25 minutes, the mixture ~as gradually heated to a ~emperature of 135C. It was maintained at that temperature for 4.5 hours, treated with an additional 10 ml of N,N-dimethylbenzylamine, and then heated for an additional 1.5 hours at 135C. After the mixture was cooled to a temperature of 70C, it was poured into a 12 Q Morton flask containing 2 ~ of methylene chloride and washed twice with 3 Q
portions of distilled water. The washed organic layer wa~ stripped of methylene chloride by distillation - first at atmospheric pressure to remove about 90 percent of the solvent, and t~en in a thin film evaporator operating at a temperature of 80C and 25 mm of mercury to remove the remainder.
The final resin weighed 1854 g. Its epoxy equivalent weight was 126 g/mole, and its viscosity at 50C was 258 centipoises. The final resin contained approximately 49 percent by weight of unreacted bis(2,3-epoxycyclopentyl) ether and 51 percent oligomers formed from the reaction of resorcinol with bi~(2,3-epoxycyclopentyl) ether.

, - 21 - ~ 3~

E ~ PL~ 4 A 500 ml, 3-necked ~lask equipped a~ in Example 1 was charged with l5o 9 of molten bis(2,3-epoxycyclopentyl) ether, g9 g of 4,4~-biphenol, and o.s g of ~-ethyl-4-methylimida~ole. The mixture was heated for 6.5 hours at 130 to 145C, followed by three hours at a temperature of 100C. At the end of this period, it wa~ transferred to a jar for storage. The final product weighed 174.5 g and ~ad an epoxy equivalent weight of 192 g/mole. Its viscosity was 13,500 cp~ at 65C. The bis(2,3-epoxycyclopentyl) ether content of the final resin was 39 percent by weight.
Control A
A two-liter flask equipped as in Example 1 was charged with 400 g of molten bis(2,3-epoxycyclo-pentyl) ether and 104 g of neopentyl glycol. The mixture was warmed to a temperature of 70C and treated with 2.0 ml of l-methylimidazole. Then it was heated to a temperature of 135C and held at that temperature for 3.5 hours. Then it was cooled to a temperature of 110C and transferred to a 12 ~ flask containing Z000 g of methylene chloride.
The resulting brown solution was washed five times with 2 Q portions of distilled water. The washed solution was stripped of methylene chloride as described in Example 1. The product, the final pot residue, had an epoxy equivalent weigh~ of 200 g/mole. It weighed 372 g and had a viscosity of 1,060 centipoises at 50C. The bi~(Z,3-epoxycyclopentyl) ether content of this re~in was 37 percent by weight.

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,.,~
A 3-liter, 4-~ecked flask equipped as in Example 1 was charged with 995 g (5.40 ~oles) of bi6(2,3-epoxycyclopentyl) ether and 275 g (2.5 moles) of resorcinol. The mixture was heated to a temperature of 100C. Then 720 g (5.0 moles) of vinyl cyclobexene diepoxide (i.e., ERL-~206 from Union Carbide Corp.) was added over a 30 minute period. Forty minutes later, 2.67 ml of l-methylimidazole was added. After an additional 3 hours at 100C, the mixture was cooled to room temperature.
~ 1050 g portion o the mixture was diluted wi~h 500 g of methylene chloride and washed t~ree time6 with 100~ ml portions of distilled water in a Morton f lask equipped with a paddle stirrer. The wa6hed orgdnic phase wa6 transferred to a 3-liter fla6~ with a paddle stirrer and distillation head.
Methylene chloride was distilled from the solution, f irst at atmospheric pressure, and then under a vacuu~ of approximately 28 inches of ~ercury for one hour with a pot temperature of 100C. The product, the pot residue, was an amber fluid which weighed 809 g. It had an epoxy equivalent weight of 117 gJmole and contained approximately 45 percent by weight of unreacted bi6 (2,3-epoxycyclopentyl~
ether, 15 percent of unreacted vinyl cyclohexene diepoxide, and 40 percent of epoxy-containing adducts derived from resorcinol, vinyl cyclohexene diepox~de, and bis(2,3-epoYycyclopentyl)ether.

A 3-liter, 4-necked flask equipped a6 in Example 1 was charged with 628 g of bis(2,3-epoxy-- ~9~3~
_ 23 -cyclopentyl) ether and';~45 g of m-aminophenol.
After the mixture reached a temperdture of 70C, it was treated with 2~8 g of vinyl cyclobexene diepoxide. The temperature of the mixture was raised to 100C. Then 2.5 ml of N,N-dimethylbenzylamine was added. Tbe mixture was heated for 2 hours at 100C and 5 hours at 120C
before being cooled to 70C. Then a 900 g portion was transferred to a 5-liter Morton flas~ containing 1500 ml of methylene chloride. The organic solution was wasbed ~ith three 1000 ml portions of distilled water. The clear amber washed solution was stripped of re~idual methylene chloride by the procedure described in Example 3. The final product weighed 603 g and had a titrated epoxy equivalent weight o 161 g/mole, after correction was made for the nitrogen in m-aminophenol, which was titrated simultaneously with epoxy groups by the tetraethylammonium bromide/perchloric acid reagent mixture. The final resin was shown by size exclusion chromatography to contain 44 percent by weight of unreacted bis(2,3-epoxycyclopentyl) ether, 6 percent of vinyl cyclohexene diepoxide, and 50 percent of oligomers derived from the reaction of m-aminophenol with bis(2,3-epoxycyclopentyl) ether and vinyl cyclohexene diepoxide. The viscosity of the final resin was 7600 centipoises at 50C.
~AMPLES 7 THROUGH 11 AND CONTROL B
Unreinforced castings were prepared Erom the epoxy compositions described in Examples 1, 2, and 4 and Control A. Typical castings weighed 100 to 160 g and had dimensions of 1/8 x 8 x 5 to 8 inches.

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All castings were cured with Tonox, a crude form of 4,4'-diaminodiphenyl methane (obtained from Uniroyal C~emicals, Naugatuck, CT.) All epoxy formulations were adjusted to epoxy equivalent weights of 150 to 171 g/mole. For most sample6, thi6 was accomplished by addition of bis(2,3-epoxy-cyclopentyl) ether.
~ he general procedure for making castings was as f 0110~8: T~e epoxy resin and additional bis-(2,3-epoxycyclopentyl) ether needed to achie~e an epoxy equivalent weight of 150 to 171 g/mole was charged to a 3-necked flask equipped with a paddle stirrer. The contents of the flask were beated to a temperature of 100 to 120C and stirred. The amine hardener was added to this solution as a fine solid. It dissolved in about two minutes. The ~esulting solution was subjected to a vacuum of about 25 inches o~ mercury ~or three minutes with agitation, followed by ~wo minutes wit~out agitation. It wa~ then poured into a glass mold with a cavity of dimension6 1/8 x 8 x 8 inches, and cured with a programmed heating cycle.
Castings were tested to determine tensile properties, heat deflection temperature, and water sensitivity. For the latter, the change in weight on immersion of tensile bars in 160F water after two weeks was recorded. Tensile properties were measured according to ASTM D-638 using a Type 1 dogbone specimen. Heat deflection temperatures were measured according to ASTM D-64~ (264 psi stre6s~.
Table I lists the component6 of each resin formulation, cure schedules, and casting properties.

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The data in T~ble I shows tbat the bis (2,3-epoxycyclopentyl~ ether copolymers derived from aromatic diphenols (e.g., hydroquinone, resorcinol, and 4,4'-biphenol) afEord unreinforced castings with superior heat deflection temperatures and reduced water uptake compared to copolymers derived from aliphatic polyols (e.g., neopentyl glycol).
EXAMPLES 11 THROUGH 13 AND CONTROLS C T~ROUGH E
A second series of unreinforced castings was prepared using the general procedure described above and m-phenylenediamine as the hardener. For each Example, a Control was prepared which had the same NH: epoxide ctiochiometry. The resin and hardener were mixed at a te~perature of 70 to 850C.
In each Example, the epoxy resin contained oligomers derived from aromatic active hydrogen compound~ and cycloaliphatic e~oxides (i.e. com~onent b of the composition) as well as unreacted cycloaliphatic epoxide (component a). When two cycloaliphatic epoxides were present in the composition of the Example, the same ratio of unreacted cycloaliphatic epoxides was present in the corresponding Control (e.g. Control C for Example 11).
All unreinforced casting~ were cured with the following cure schedule: 5 hours at 95C: heat at 1C per minute to 120C; ~old 4 hours at 120C;
heat at 1C per minute to 160C; hold 6 hours at 160C.
Example 13 describes an epoxy composition of this invention which was prepared by blending 80 g of bis (2,3-epoxycyclopeneyl) ether with 40 9 of ~Fo~tifier C" (a product of Uniroyal Canada, Guelph, ontario, Canada). The latter was a reaction product - 26 - ~9~f3~

of aniline and vinyl cyclohexene diepoxide which contained 33 percent b~ weight of unreacted diepoxide, and 67 percent of a mixture of oligomers containing approximately 3 moles of diepoxide per mole of aniline. The epoxy equivalent weight of Fortifier C was 1~0 g/mol, after a correction was made for the nitrogen derived from aniline.
The tensile properties and heat deflection temperatures of this series of castings are shown in ~able II. All compo6ition6 containing component b of this invention provide unreinforced castings with increased tensile moduli compared to the appropriate Control. The modulus is a bulk property of the material, unlike strength and elongation, which are sensitive to defects in the sample. Thus an increased matrix modulu~ should result in an increased composite modulus.
~AMPL~ 14 Another unreinforced ca6ting was prepared using 100 g of the composition of Example 3 and 23.6 of m-phenylenediamine using the procedures described for Examples 11 through 13. The properties of the casting were as follows: tensile strength: 16,700 psi; tensile modulus: 624,000 p6i; elongation: 3.9 percent; and heat deflection temperature 174C.
The viscosity of thi~ epoxy/hardener mixture at 85C was measured. The data i~ shown in Table III, along with data for a Control Resin with the same epoxy equivalent weight derived from an aliphatic polyol. These data ~how that the compositions of thi~ invention cu~e more rapidly t~an those based on aliphatic polyols.

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-- D_ Example lS describes the preparation of unidirectional carbon fiber prepreg. The carbon fiber was based on polyacrylonitrile. It contained 6000 filaments per tow. The filament tensile trengtb was 6.6 x 105 psi and the tensile modulu6 was 36 x 1o6 p8i. Prepreg with a nominal width of 6 inches and a nominal thickness of 6 mils was prepared.

A 3 liter, 4-necked flask equipped as in Example 1 was charged with 900 g of the epoxy resin prepared in Example 3. The contents of the flask were heated to a temperature of 85C. Then 212 g of m-phenylenediamine wa~ added over a lS minute period. The mixture wa~ maintained at a temperature of 82 to 92C for 1 hour after completion of addition the hardener in order to partially advance it. This B-staged resin was poured into the pan of a knife-over-roll coater at a temperature of 80C
and coated in a seven inch width at a coating weight of 4.0 g/sq ft.
Preimpregnated tape was prepared by sandwiching a fiiX inch wide ribbon of carbon fiber tows between two plies of release paper and melting tbe resin into the fibers under the action of heat and pressure in a prepreg machine. The re6in content of the final tape was 37 percent by weight.

Example 16 describes the fabrication and testing of a unidirectional composite for longitudinal tensile properties.

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EXAMP~E~6 ,, A unidirectional laminate was prepared by stacking 8 plies of the preimpregnated tape made in Examp-e 15 in a mold, covering them with a teflon impreqnated fabric spacer and bleeder cloths, and enclosing them in a nylon bag. The entire as6embly was placed in an autoclave and cured. ~ongitudinal tensile properties were measured at ambient temperature according to ASTM-D3039. The results and cure schedule are shown in Table IV.
Example 17 describes the fabrication and testing of a unidirectional composite for transverse tensile properties.

A unidirectional laminate was prepared by stacking 20 plies of 6-inch wide tape in a mold and curing it in an autoclave.
Transverse tensile specimens were prepared from the cured laminate and were tested according to ASTM-D3039. The results and cure schedule are shown in Table IV.

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Table IV
COMPOSITE PROPERTIES a Lonoitudinal Layup Example 16 Tensile Strength (103 p~i) 355 Tensile Modulus (106 p6i) 20.6 Strain-to-Failure (%) 1.54 Fiber Content (vol %) Sl.2 Trans~erse Layup Example 17 Tensile Strength (103 psi) 10.5 Tensile Modulus (106 psi) 1.56 Strain-to-Failure (%) 0.71 Fiber Content (vol %) 59 Cure Schedule:
Apply vacuum to bag. Pressurize autoclave to B5 p8i . Heat from 70F to 240F at 3F/min.
Hold 1 hour at 240F. Then. vent bag to the atmospbere and increase autoclave pressure to 100 psi. Heat from 240P to 350F at 3F/min. Hold at 350F for 6 hours.
It is clear that the composition6 of this invention provide composites with a high level of mechanical properties. The high tran~verse modulus reflects the high matrix modulus. The transverse strength and strain tO failure are superior to those measured on composites made with state of the art matrix resins.

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Claims

1. A composition comprising:
a cycloaliphatic epoxy resin selected from bis(2,3-epoxycyclopentyl) ether, 4-(1,2-epoxyethyl)-1,2-epoxycyclohexane, 1,4-cyclohexadiene diepoxide and mixtures thereof;
an adduct of an epoxy resin with a phenolic compound selected from biphenol, resorcinol and hydroquinone; and an aromatic amine hardener selected from:
4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl methane, 3,3'-diaminodiphenyl methane, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 3,3'-diaminobenzophenone, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylsulfide, 1,4-bis(p-aminophenoxy) benzene, 1,4-bis(m-aminophenoxy) benzene, 1,3-bis(m-aminophenoxy) benzene, 1,3-bis(p-aminophenoxy) benzene, 4,4'-bis(3-aminophenoxy) dipheny1 sulfone, trimethylene glycol di-p-aminobenzoate, 2,2-bis(4-aminophenoxyphenyl)propane, and diethyltoluene diamine.

2. The composition of Claim 1 further comprising up to 30 percent by weight of acoepoxy resin.

3. The composition of Claim 2 wherein said coepoxy resin is selected from phenol-formaldehyde novolak and cresol-formaldehyde novolak.

4. The composition of Claims 1-3 further comprising a structural fiber selected from the group consisting of carbon, graphite, glass boron, silicon carbide and aromatic polyamides.

5. The composition of Claim 4 in the form of a prepreg.

6. The composition of Claims 1 or 4 further comprising a thermoplastic selected from the group consisting of polysulfone, polyhydroxyether, and polyamide.

94,285