CA1270589A - Curable mixtures containing an epoxy resin, an imidazolide and a polysulfone - Google Patents
Curable mixtures containing an epoxy resin, an imidazolide and a polysulfoneInfo
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- CA1270589A CA1270589A CA000503399A CA503399A CA1270589A CA 1270589 A CA1270589 A CA 1270589A CA 000503399 A CA000503399 A CA 000503399A CA 503399 A CA503399 A CA 503399A CA 1270589 A CA1270589 A CA 1270589A
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- Prior art keywords
- mixture according
- epoxy resin
- weight
- polysulfone
- parts
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G59/00—Polycondensates containing more than one epoxy group per molecule; Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups
- C08G59/18—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing
- C08G59/40—Macromolecules obtained by polymerising compounds containing more than one epoxy group per molecule using curing agents or catalysts which react with the epoxy groups ; e.g. general methods of curing characterised by the curing agents used
- C08G59/4007—Curing agents not provided for by the groups C08G59/42 - C08G59/66
- C08G59/4014—Nitrogen containing compounds
- C08G59/4042—Imines; Imides
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L63/00—Compositions of epoxy resins; Compositions of derivatives of epoxy resins
Abstract
Curable mixtures containing an epoxy resin, an imidazolide and a polysulfone Abstract of the Disclosure Storage-stable heat-curable mixtures containing (a) 100 parts by weight of an epoxy resin, (b) 3 to 15 parts by weight of an imidazolide of formula I
wherein e.g. R1 is phenyl, each of R2, R3, R5 and R7 is hydrogen and each of R4, R6 and R8 is methyl, and (c) 2 to 50 parts by weight of a thermoplastic polysulfone with an average molecular weight of at least 10 000.
Said mixtures are suitable in particular for the preparation of moulded articles, prepregs and adhesive films with excellent thermal and mechanical properties.
wherein e.g. R1 is phenyl, each of R2, R3, R5 and R7 is hydrogen and each of R4, R6 and R8 is methyl, and (c) 2 to 50 parts by weight of a thermoplastic polysulfone with an average molecular weight of at least 10 000.
Said mixtures are suitable in particular for the preparation of moulded articles, prepregs and adhesive films with excellent thermal and mechanical properties.
Description
~0~i89 3-15282/~
Curable mixtures containing an epoxy resin, an imidazolide and a polysulfona __ _ _ The inventlon relates to storage-stable, heat-curabls mixtures containing an epoxy resin, an imidazolide (N-acylimidazole) as hardener for the epoxy resin and a thermoplastic polysulfone, as w811 as to the use of said mlxtures for the preparatlon af moulded article~, in particular of p~epr~gs for fibre reinforced compo~ites and of adhesive films.
Mixtures consisting of an epoxy resin, a thermoplast aDd a hardener for the epoxy re~ln are known from Japanese published patent application 83 49718. The thermopla~t may, inter alia, al~o be a polysulfone, and, in additlon to other compounds, imidazole~ are also used as hardeners. Further, imidazolldes (N-acylimidazole~) are disclosed as hardeners for epoxy reslns in Japanese patent specifi-catlon 743 212, ln German Offenlegungsschrift 32 46 072 and in European published application 0 124 482.
The present invention relates to ~torage-stable, heat-curable mixtures containing (a) 100 parts by weight of an epoxy resin, b) 3 to 15 parts by weight of an imidazolide of formula I
~ 2 R6- ~ ~ ~ ll (I), ~;~7~S89 wherein each of Rl, R2 and R3 independently of one another is hydrogen, Cl-CI2alkyl, Cs-CIacycloalkyl or C6-CIoaryl and each of R~
to R8 independnntly of one another i9 hydro8en, Cl-C12alkyl, halogen~ nitro or trifluoromethyl, with the proviso that the substi~nents R4 and R8 are not simultaneously hydrogen, and (c) 2 to 50 part~ by weight of a thermoplastic polysulfone with an aversge molecular weight of at least 10 000.
The mixtures of the invention are suitable for the preparation of moulded articles, prepregs and adhesive film~, and the cured products poasess excellent thermal and mechanical properties, in particulsr a high stabillty to thermal ageing as well as a good fracture toughness and moisture resistance.
The mixtures al~o possess excellent processing propertie~ such a~ a high homogenity, a long pot life and a favourable tack which i5 preserved even after prolonged storage at room temperature.
Suitable epoxy resins (a) for the mixtures of the invention are all those epoxy resins which can be cured with the imidazolides of formula I.
Example of suitable epoxy resins are di- or polyglycidyl etherg of cycloaliphatic polyols, such as 2,2-bis(4'-hydroxycyclohexyl)pro-pane, dl- or polyglycidyl ethers of polyhydric phenols, such as resorcinol, bi~(4'-hydroxyphenyl)methane (bisphenol F), 2,2-bis-(4'-hydroxyphenyl)propane (bisphenol ~, 2,2-bis(4'-hydroxy-3',5'-dibromophenyl)propane, 1,1,2,2-tetrakis(4'-hydroxyphenyl)ethane, or condensation product~ of phenols with formaldehyde, such as phenol novolaks and cresol novolak~; and also di- or poly(~-methylglycidyl) ethers of the above polyalcohols and polyphenols; polyglycidyl esters and poly(~-methylglycidyl) esters of polyvalent carboxylic acid~, such as phthalic acid, terephthalic acid, tetrahydrophthalic acid and hexahydrophthalic acid; N-glycidyl derlvatives of amines, amides and heterocyclic nitrogen bases, such as N,N-diglycidylani-~27~5~3 line, N,N-diglycldyltoluidine, N,N,N',N'-tetraglycidyl bls(4-amino-phenyl)methane, triglycidylisocyanurate, N,N-diglyoidyl-N,N'-ethyleneurea, N,N'-diglycidyl-5,5-dimethylhydaDtoin, N,N'-dlglycl-dyl-5-isopropylhydantoin, N,N'-diglycidyl-5,5-dimethyl-6-isopropyl-5,6-dihydrouracil.
In general, mixtures of two or more epoxy raslns may also be used in the curabls mixtures of the invention.
Particularly 6uitable are epoxy resin~ with an epoxide content of 5 to 9 equivalents per kg and which are glycidyl ethers, glycidyl esters or N-glycidyl derivative~ of cycloaliphatic compounds or, preferably, of aromatic or heterocyclic compounds.
Preferred epoxy resins are epoxy novolaks, glycidyl derivatives of bisphenols, of aromatic diamines, of aromatic or cycloaliphatic dicarboxylic acids, of hydantoins or of lsocyanuric acid. Part$cu-larly preferred epoxy resins are epoxy phenol novolaks and glycidyl derivatives of bi~phenol A, bisphenol F, hexahydrophthalic acid or 4,4'-diaminodiphenylmethane as well as triglycidyl-bishydantoins or mixtures of such resins. Particularly suitable mixtures o~ epoxy resins as component (a) sre mixtures of an epoxy phenol novolak with glycidyl derivatives of bi~phenol A, bisphenol F, 4,4'-diaminophe-nylmethane or with triglycidyl-bishydantoins, as well as mixtures of a glycidyl derivative o~ bisphenol F with tetrafunctional epoxy resins, e.g. bi3(N,N-diglycidyl-4-aminophenyl)sulfone, bi~(N,N-di-glycityl-4-aminophenyl) ether or 2,2-bis(N',N'-diglycidyl-4'amino-phenyl)propane. A particularly preferred epoxy resin (a) is a mixture of bisphenol F diglycidyl ether and bis(N,N-diglycidyl-4-aminophenyl)methane.
The imidazolides of formula I employed in the mixtures of this invention are known or they can be prepared in a manner known per se. They are suitably prepared by reacting an acid hallde oE
formula II
~2~ 39 ~. 8 ( II) R~ ~
with an imidazole of formula III
H ~\ ~ (III) I
~,1 in wh$ch formulae X i~ chlorine or bromine, and the symbols Rl to R3 are as defined above. Some of these imidazolides and the preparation thexeof are described in the sbove-cited Japanese patent specifica-tion 743 212, German Offenlegungsschrift 32 46 072 and European publi~hed application 0 124 482.
Each of the substituents Rl to R3 independ0ntly of one another may be a branched or, preferably, straight chain alkyl group containing 1 to 12, preferably 1 to 6 and most pr0ferably 1 to 4, carbon atoms.
Fxamples of suitable alkyl groups are dodecyl, decyl, o~tyl, heptyl, butyl, propyl and, most preferably, isopropyl, ethyl or methyl.
If one or more of the sub3tltuents Rl to R3 18 a cycloalkyl group, then the preferred meanings are cyclopentyl and cyclohexyl, ench of which may be ~ubstltuted by one or more Cl-C3alkyl groups. Said groups sre preeerably unsubatituted.
If one or more of the substituents Rl to R3 is an aryl group, then the pseferred meaning~ are phenyl and naphthyl. Tbe subst~tuents R4 to R3 as halogen are iodine or bromine or, preferably, chlorine.
In the mixtures of the present invention, it is preferred to employ imidazolide~ (b) wherein each of the substituents R2, R3, Rs and R7 is hydrogen, the substituent Rl is Cl-C4alkyl or phenyl and each of ~L27~5~
the substituentg R4, R6 and R~ independently of one another is hydrogen, C1-C4alkyl or halogen. Particulnrly preferred imidazolides of formula I are thosa wherein each of R2, R3, Rs and R7 1~ hydro-gen, Rl i8 methyl, ethyl or phenyl snd R6 i8 hydrogen or methyl and each of R4 and RB i8 chlorine or methyl. More particularly preferred imidazolides whlch can be employed in the mixtures of the invention are 1-(2',6'-dichlorobenzoyl)-2-phenylimidazols, 1-(2',4',6'-trime-thylbenzoyl3-2-ethylimidazole, 1-(2',6'-dichlorobenzoyl)-2-methyl-imidazole, 1-(2',4',6'-trimethylbenzoyl)-2-methylimida701e and, mo6t preferably, 1-(2',4',6'-trimethylbenzoyl)-2-phenylimidazole.
The imidazolides of formula I which can be employed in the mixture~
of the invention are highly react~ve hardener3 at elevated tempera-ture, but are stable at room temperature, making longer storaga and proces~ing times possible.
Suitable polysulfone resins (c) are e.g. those containing the recurring element of the formula -A-S0z-wherein A iB 8 divalent aromatic group which may be interrupted by sther oxygen atoms and/or by divalent aliphatlc groups. Preferably, the polysulfone has a heat deflection temperature of at least 150C, as mea3ured in accordance with ASTM Specification D648.
The polysulfones to be employed may be obtalned in ~nown manner e.g.
by heating either (a) a sulEonyl halide uf the formula HAlSOzX or ~b) a mixture of a dlsulfonyl halide of the formula XSOzAISO~X with a sul$onyl halide-free compound of the formula HAzH, in which formulae Al and A2 are identical or different and each is a divalent aromatic group which may be interrupted by ether oxygen atoms and/or by divalent aliphatic groups, and X i8 a chlorine or bromine atom, in an inert solvent and in the pre~ence of a Lewis acid catalyst.
The poly~ulfones prepared in accordance with process (a) contain the recurring element 7~5~
whereas those prepared in sccordance with procQAs (b) contain the recurring element -Al-SOz-A2-S02-Polysulfone resins preferred for use in the mixtures of the present invention are those which contain ether groups in the recurring element but which are free from hydroxyl groups in a side chain.
These are particularly preferred polysulfones containing a recur-ring element of the formula wherein A3 and A4 ars divalent aryl groups, preferably phenylene groups, which may be substituted by chlorine or C1-C4alkyl, e.g.
methyl groups. Such polysulfones can be obtained in a manner known per se by rencting a dialkali metal salt of a dihydric phenol of the formula HOA30H with a bis~monochloroaryl)sulfone of the formula ClA4SOzA4Cl in dimethyl sulfoxide. More preferred polysulfone resins are those containing a recurring element of the formula -OAs-Y-AsOA6-SO2-A6-wherein each of A5 and A6 is a phenylene group which is unsubstitu-ted or substituted by chlorine or Cl-C4alkyl groups, e.g. methyl groups, and Y is a carbon-carbon bond, the group -SO2- or an aliphatic hydrocarbon group, preferably one containing not more than four carbon atoms, such as those of the formula -CH2- or - :-~:7~89 ~ 7 _ 21~89-69~9 Particularly preferred are thermoplastic polysulfone resins contain-ing recurring elements oE Eormula IV
t ~ soz ~ ~ ~ ( IV) .=. .=. .=. '=- n wherein n preferably has an average value of 50 to 120.
Particularly advantageous polysulfones are e.g. those available from the Union Carbide Corporation such as "Polysulfone Udel P1800~"
which according to the manufacturer has a melting point in the range from 350 to 370C, a heat deflection temperature (ASTM Specifica-tion D648) of 175~C and contains per average molecule 50 to 80 recurring elements of formula IV, indicating a molecular weight range of about 22 000 to 35 000.
A further suitable polysulfone is a similar substance available from the Union Carbide Corporation under the name "Polysulfone P2300~"
which according to the manufacturer has a molecular weight range of 30 000 to 50 000, indicating that the substance contains per average molecule about 68 to 113 recurrlng elements of Eormula IV. Also suitable i9 a similar substance available from the Union Carbide Corporation under the name "PolysulEone P3500~" which according to the manufacturer has a molecular weight range lying between that of "Yolysulfone Udel P1800~" and that of "PolysulEone P2300~"; the molecular weight is about 35 000.
Mixtures of t~o or more polysulfones may also be employed as component (c) in the curable mixtures of this :Lnvention.
The epoxy resin (a) and the polysulfone (c) of the mixtures of the present invention are preferably chosen such that the polysulfone is soluble in the epoxy resin and that, after the epoxy resin has been ~ . , ~705~39 cured, two phase3 form which are flnely disper~ed ln each other.
Such sy6tems produce cured products wlth particularly good proper-ties.
Preferred are also those mixtures of the inventlon which, in addition to the above-mentioned components (a) to (c~, contain as component (d) 1 to 12 parts by weight, preferably 2 to 6 part6 by weight, of a finely particulate filler, based on 100 parts by weight of epoxy re6in (a), the pri~ary particles of which flller have an average size of 2 to 100 nm, pref~rably 3 to 30 nm and most prefsr-ably 5 to 15 nm. Particularly suitable fillers (d) are titanium dioxide and, e~pecially, silicon dioxide or aluminium oxide. Such fillers are available e.g. froM the firm Degussa (Switzerland) AG, Zurich, under the name Aerosil~ and Alox C~ and, depending on the product, the primary particles thereof have an average siza of 7 to 12 nm. The addition of the above finely particulate fillers improves in particular the dynamic properties of the mixtures of the invention, which can be determined e.g. in a dynamic alternate bending test on laminates prepared using said mixtures.
It is preferred to employ mixtures of the invention in which the proportions of the component3 (b) and (c) independently of each other are: imidazolide (b) 4 to 12 parts by weight, preferably 5 to 8 parts by weight, and polysulfone (c) 5 to 30 parts by weight, preferably 8 to 15 parts hy weight, each based on 100 parts by weight of the epoxy resin (a).
In the case of mixtures which additionally contain as component (d) a finely particulate filler, lt is preferred to use such mixtures in which the proportion of the polysulfone ~c) iD 10 to 40 parts by weight, preferably 12 to 25 parts by weight, based on 100 parts by weight of the epoxy resin (a).
The mixtures of the invention can be prepared by thoroughly mixing all components or by dissolving them in each other. The indlvidual components may be added in varying sequence. The polysulfone can ~t70S89 _ 9 _ e.g. be dissolved under heat ln the epoxy re~ln, ~nd ~ftor cooling the 601ution to about 120C, the lmidazolide hardener and, iE
desired, the finaly particulate filler or further additives may then be added. If using a finely particulate filler, this i9 preferably fir~t ground down with the epoxy resin in a three-roll mill and the polysulfone is subsequently di6solved in the epoxy resin.
The mixtures o$ the invention have many U~e8 and are suitable for example as casting resins, laminating or impregnating resin3, moulding compositions, sealing compo6itions, embedding or insulating compositions for the electrical industry snd, preferably, as adhesives and as matrix re6in~ for composites, in particular for the preparation of fibra reinforced plastics.
If desired, in particular when using modification agents, the mixtures of the invention may be dissolved in an organic solvent such as toluene, xylene, methyl ethyl ketone or methylene chloride or in a similar solvent or mixture of ~olvent~ customarily employed ln the varnish industry. Such solutions are suitable in particular as impregnating agents or coating agents.
In any phase before curing, customary modification agents may be added to the curable mixtures of the inventlon. Examples of such modification agents are: extenders, fillers, reinforcing agents, pigments, dyes, organic solvents, plasticisers, levelling agents, thixotropic agents, flame retardants or mould release agents.
Examples of extenders, reinforcing agents, fillers snd pigments which may be employed in the curable mixtures of the invention are:
liquid coumarone-indene resins, textile fibres, glass fibres, asbestos fibre~, boron fibres, carbon fibres, polyethylenc powder, polypropylene powder, quartz powder, mineral silicates such as mica, asbestos powder, powdered slate, kaolin, powdered chalk, antimony trioxide, bentone, lithophone, heavy 6par, titanium dioxide, carbon black, graphite, oxide pigments such as iron oxide, or metal powder~ such as aluminium powder or iron powder.
~'~7~ 9 Extenders which may be added when employing the curable mixtures in particular for surface protection are e.g.: silicone6, liquid acrylic re~ins, cellulose acetobutyrate, polyvlnyl butyral, waxas, stearates etc. (some of which are also employed as Moulcl relea~e agents).
Examples of pla~ticisers which may be employed for the modiflcation of the curable mixtures are: dibutyl phthalate, dioctyl phthala~e, dinonyl phthalate, tricresyl phosphate, trixylenyl pho~phate and diphenoxyethyl formal.
The mixtures of the invention are preferably cured by heating them to a temperature in the range from 120 to 250C, in particular from 150 to 200C. The curing may also be carried out in two or more steps in known manner, with tha first curing step being carried out at low temperature and the postcuring at elevated temperature.
If desired, active diluents may be added to the mixtures of the invention in order to reduce the viscosity. Examples of such diluents are: styrene oxide, butyl glycidyl ether, 2,2,4-trimethyl-pentyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, glycidyl esters of synthet$c, highly branched, mainly tertiary, aliphatic monocarboxylic acids.
Curing accelerators may also be employed for the curing; examples of such accelerators ars: tertiary amines, the salts or quaternary ammonlum compounds thereof, e.g. benzyldimethylamine, 2,4,6-tris-(dimethylamlnomethyl)phenol, l-methylimidazols, 2-ethyl-4-methyl-imidazole, 4-aminopyridins, trLpentylammonium phenolate; or alkali metal alcoholates, e.g. sodium hexane triolate.
The present invention also relates to the use of the mixtures of the invention for the preparation of cured moulded articles, as well as to the use thereof for the preparation of prepregs for fibre reinforced composites or of adhe~ive films. The prepregs and the adhesive films can be prepared in a manner known per se, a.g. by the 1~7~
lmpregnating process in the presence of one of the abov0 solvents or of a halogenated solvent such aA methylene chlorlde, or by the hot melt process.
In general, thc moulding compositions of the invention, while at the same time having high mechanical strength, sre dlstingulshed by relatively high glasD transition temperatures. Particular feature3 of said compositions are their excellent stability to thermal ageing, excsllent fracture toughness and moisture resi~tance.
The invention i9 illustrated in more detail by the following Example~.
The components (a) to (d) employed in the following Examples are as follows:
Epoxy resin 1: An epoxy phenol novolak with an epoxide content of 5.7 equivalents/kg and a viscosity of about 2.0 Pa-s at 52C, which novolak is in the liquid state at room temperature.
Epoxy resin_2. A tetraglycidyl derivative of 4,4'-diaminophenylme-thane with an epoxide content of 7.8 equivalents/kg and a viscosity of about 1.3 Pa~s at 50C.
Epoxy resin 3: A triglycidyl bishydantoin of formula V with an epoxide content of 5.6 equivalents/kg and a ViSCoBity of about 1.3 Pa~s at 80C
CIH3 ,CH3 CH~-/cH2-cH2- ~ CHz- ~H-CHz- ~\ ~ -CHz-C~7CH2 (V).
~ H 2 ~, 0\ Hz ~ ~ ~705~3~
Epoxy resin 4: A blsphenol A diglycidyl ether with an epoxide content of 5.4 equlvalent~/kg and a vi~cosity of 1.0 Pa~6 at 25C.
Epoxy regin 5~ Crystalline bisphenol F diglycidyl ether with an epoxide content of 6.4 equivalents/kg.
Epoxy resin 6: Hexahydrophthalic acid diglycidyl e~ter with an epoxide content of 5.9 equivalents/kg and a viscosity of 0.~ Pa-s at 25C.
Polysulfone 1 Polysulfone Udel Pl800~ (Union Carbide Corporation) with a melting point in the range from 350 to 370C, a heat deflection temperature (in accordance with ASTM D648) of 175C and a molecular welght range of about 22 000 to 35 000.
Imidazolide l: 1-(2',4',6'-Trimethylbenzoyl)-2-phenylimidazole, prepared in accordance with European published application 0 124 482.
Imidazolide 2- 1-(2',6'-dichlorobenzoyl)-2-phenylimidazole, prepared in accordance with German Offenlegung~schrift 32 46 072.
Imidazolide 3. 1-(2',4',6'-Trimethylbenzoyl)-2-ethylimidazole, prepared in accordance with European published appllcation 0 124 482.
Imidazolide 4: 1-(2',6'-dichlorobenzoyl)-2-methyllmidazola, prepared in accordance with German Offenlegungsschrif-t 32 46 072.
Imidazolide 5~ 2'~4',6'-Trlmethylbenzoyl)~2-methylimidazole, prepared in accordance with European published application 0 124 482.
Alox C~. Finely particulate aluminium oxide available from Degussa (Switzerland) AG, Zurich. Average ~ize of the primary particles:
10 nm.
~271~358~:~
Aerosll 300~: Finely part~culate ~ilicoD dioxide avallable from _ . _ Degus6a (Switzerland) AG, Zurich. Average size of the primary particles: 7 nm.
Example 1: 20 g of polysulfone 1 are dlssolved at 200C in 160 g o~
epoxy resin 1. The solution is cooled to 120C and then m~xed with 40 g of epoxy resin 2 and 12 g of imidazolide 1. A proportion of the mixture i9 poured into an Anticorodal mould (200 x 200 x 4 mm) and cured for 2 hour~ st 150C and 2 hours at 180C. A further propor-tion of the mixture i~ used for measuring the fracture toughness by the double tor~ion test following the procedure described in "Journal of Materials Science", 10, 1334 (1975) and 14, 776 (1979).
In this test, two aluminium plate8 [Extrudal 050 AlMgSi 0.5 (200 x 20 x 5 mm)] which have been treated with chromosulfuric acid are cemented with the curable mixture and the bond is cured, as described above, under slight pressure. In the measurement proce-dure, the crack propagation in the bond is determined, i.e. the breaking energy in J/m2 is calculated from the maximum load for the crack propagation.
The following results are obtsined:
flaxural strength (FS) in accordance with ISO 178 ~ 112 MPa edge fibre elongation (EFE) at the moment oE fracture ln accordance with ISO 178 u 6.8 %
glass transitlon temperature (T ) measured with the thermomechanical analyser of the company Mettler AG, Grelfensee, Switzerlsnd ~ 177C
fracture toughness (FT), double torsion te~t ~ 212 Jlm2 Example 2: In accordance wlth the procedure of Example 1, a further test i~ carried out u~ing 200 g of epoxy resin 1, 12 g of imidazo-lide 1 and dlfferent amounts of the polysulfone 1. The following results are obtained (an additional flexural test is carried out after 10 days' storage ln water at 85C):
~7~5~
A~ 5 8 ~ ~5 g Z(J g 25 g FS (MPa) llO 114 115 112 113 FS (after H20) ~MPa~ 102 97 106 107 99 EFE t%) 6.2 6.7 7.1 7.5 6.7 E~E (after H20) (%) 4.9 4.4 5.4 5.7 4~5 FT (J/m2) 91 231 206 150 140 Example 3: In accordance with the procedure of Example l, 48 g of polysulfone l are dissolved in 400 g of epoxy resin 1, and the solution is subsequently mlxed with 40 g of epoxy resin 3 and 24 g of ~midazolide l. A proportion of the mixture is cured a~ described in Example 1. The moulded articles have the following properties:
FS 113 MPa ~FE 5.35 %
FT 276 J¦m2 256 g of the mixture are dis301ved in l50 g of CH2Cl2 for a further test. A unidirectional prepreg is prepared with carbon fibres T 300-50 B (Toray) by the impregnatlng method. The prepreg, which is obtained after the solvent has been distilled off, exhibits a good tack which is pressrved even after storage for several weeks at room temperature. Tho gelling time of the prepreg is 66 minutes at 120C
or 13 minutes at 160C. The prepreg is moulded to a laminate and cured for 2 hours at 150C and 2 hours at l80C. A laminate (60 % by volume of fibres) with a flexural strength of 1290 MPa in the direction of the fibre and 65 MPs across the fibre ig obtained.
After ageing in air for 30 days at 180C, the flexural strength in the direction of the fibre ls l360 MPa and acros~ the fibre is 77 MPa, which demonstrates that the composition of the invention has a high ~tability to ageing.
~L~7~8~
- 15 - 21~89-6~09 Example 4:
a) 48 g of polysulfone 1 are dissolved under heat in 400 g of epo~y resin 1, and the solution is mixed with 24 g oE imida~olide 1.
b) A second mixture is prepared following the procedure indicated under (a) but also admixing 8 g of Alox C~ in a three-roll mill.
c) A further mixture is prepared following the procedure indicated under (b) but using 16 g of Alox C~.
The moulded articles prepared according to Example 1 have the following properties:
a b c T (C) 174 174 174 FS (MPa) 109 112 101 EFE (%) 5.3 5.7 5.1 EFE (after 10 d HzO, 85C)(%) 4.7 4.6 5.3 TAS*, 25C (MPa) 98 95 96 TAS*, 120C (MPa) 50 63 66 FT (J/m2) 209 194 150 * In order to determine the torsion adhesive strength (TAS), aluminium pivots are cemented in accordance with the procedure for measuring with the "Twist-o-meter~" (The Epprecht Company, Instru-ments ~ Controls, Bassersdorf, Switzerland). To this end, the curable mixture i9 heated, with stirring, to 120C until a homogene-ous solution of low vlscosity is obtained. 5 bonds are prepared from the solution after it has cooled to room temperature. These bonds are then cured by heating for 2 hours at 150C and 2 hours at 180C.
Prepregs are prepared from the three mixtures (a), (b) and (c) with a glass fibre weave of 80/20 (mZ weight: 375 g/m2) by the hot melt process. The prepregs are distinguished by good tack. Laminates are prepared from the prepregs (12 layers) in the press (curing: 2 hours at 150 ~ 2 hours at 180~C). In the main fibre direction the .
laminates have a flexural strength of 550-600 MPa. In a dynamic alternate bending tes~ (4-point support of samples 100 x 20 x 4 mm3), the lamlnate (a) under a load of ~ 200 MPa has a working life of 8 x 105 load changss ~drop in tension to 40 % with the max. deformation remalning constant), (b) has a working life of 2S x 105 load changes and (c) a working life of 80 x 10S load changes undsr the same conditions.
Example 5: ~y using a mixture which i8 otherwise ldentical to that in Example 4b but contains, in place of Alox C~, 8 g of Aerosil 300~
which have been treated with a s~lane, ~oulded articles are obtained which have the following properties:
Tg 179C
FS 95 MPa EFE 4.2 %
FT 163 J/m2 Example 6: 30 g of epoxy resin 1 are thoroughly mixed, under heat, with 70 g of epoxy resin 4 and 10 g of polysulfone 1. The mixture is cooled to 120~C and 6 g of imidazolide 2 are admlxed. The mlxture is then processed and cured ln accordance with the procedure of Example 1. The moulded artlcles obtained have the following proper-ties:
FS 97 MPa EFE 5.2 %
g Example 7 50 g of epoxy re~in 2 are thoroughly mixed, under heat, with 50 g of epoxy resin 5 and 15 g of polysulfone 1. The mixture is cooled to about 120C and 6 g of imidazollde 3 are admixed. The mixture i3 then processed and cured ln accordance with the procedure of Example 1. The moulded artlcle~ obtained have the followlng properties:
FS 116 MPa EFE 9.6 %
~g 175C
Example 8: 50 g of epoxy reDin 2 are thoroughly mixed with 50 g of epoxy resin 5 and 2 g of Alox C~ and the mixture is ground down in a three-roll mill for about 20 minutes. The mixture i8 then heatad to about 180C, mixed with 20 g of polysulfone 1 and stirred until the polysulfone has dissol~ed. The solution is cooled to 140C, mixed with 6 g of imidazolide 1 and then processed in accordance wlth the procedure of Example 1:
The following properties are determined:
FS 122 MPa EFE 7.5 %
Tg 179C
FT 196 J/m2 Example 9: By following a procedure analogous to that of Example 8, a polymer con~isting of 30 g of epoxy resin 2, 70 g of epoxy resin 5, 5 g of Alox C~, 24 g of polysulfone 1 and 6 g of imidazolide 1 i~ prepared. The cured polymer has the following properties:
FS 123 MPa EFE 7.3 %
Tg 166C
FT 385 J/m2 Example 10: 60 g of the mixture prepared in accordance with Example 9 conaisting of epoxy resins 2 and 5, Alox G~ and polysul-fone 1 are di~solved :Ln 40 g of methylene chloride, and the solution is ~horoughly mixed with 2.3 g of imidazolide 1.
~o'~ 9 ^ 18 -A glas9 fibre weave 80l20 i9 impregnated with tha solution ualng a doctor knife, and the solvent 18 evaporated off wlth a gentle curren~ of alr. A transparent prepreg with good tack i8 obtained.
The prepreg can be stored for over a month at room temperature without any changes in tack. 14 layers of prepreg are moulded to a laminate plate of 4 mm thlckness and the plate is then ou~ed for
Curable mixtures containing an epoxy resin, an imidazolide and a polysulfona __ _ _ The inventlon relates to storage-stable, heat-curabls mixtures containing an epoxy resin, an imidazolide (N-acylimidazole) as hardener for the epoxy resin and a thermoplastic polysulfone, as w811 as to the use of said mlxtures for the preparatlon af moulded article~, in particular of p~epr~gs for fibre reinforced compo~ites and of adhesive films.
Mixtures consisting of an epoxy resin, a thermoplast aDd a hardener for the epoxy re~ln are known from Japanese published patent application 83 49718. The thermopla~t may, inter alia, al~o be a polysulfone, and, in additlon to other compounds, imidazole~ are also used as hardeners. Further, imidazolldes (N-acylimidazole~) are disclosed as hardeners for epoxy reslns in Japanese patent specifi-catlon 743 212, ln German Offenlegungsschrift 32 46 072 and in European published application 0 124 482.
The present invention relates to ~torage-stable, heat-curable mixtures containing (a) 100 parts by weight of an epoxy resin, b) 3 to 15 parts by weight of an imidazolide of formula I
~ 2 R6- ~ ~ ~ ll (I), ~;~7~S89 wherein each of Rl, R2 and R3 independently of one another is hydrogen, Cl-CI2alkyl, Cs-CIacycloalkyl or C6-CIoaryl and each of R~
to R8 independnntly of one another i9 hydro8en, Cl-C12alkyl, halogen~ nitro or trifluoromethyl, with the proviso that the substi~nents R4 and R8 are not simultaneously hydrogen, and (c) 2 to 50 part~ by weight of a thermoplastic polysulfone with an aversge molecular weight of at least 10 000.
The mixtures of the invention are suitable for the preparation of moulded articles, prepregs and adhesive film~, and the cured products poasess excellent thermal and mechanical properties, in particulsr a high stabillty to thermal ageing as well as a good fracture toughness and moisture resistance.
The mixtures al~o possess excellent processing propertie~ such a~ a high homogenity, a long pot life and a favourable tack which i5 preserved even after prolonged storage at room temperature.
Suitable epoxy resins (a) for the mixtures of the invention are all those epoxy resins which can be cured with the imidazolides of formula I.
Example of suitable epoxy resins are di- or polyglycidyl etherg of cycloaliphatic polyols, such as 2,2-bis(4'-hydroxycyclohexyl)pro-pane, dl- or polyglycidyl ethers of polyhydric phenols, such as resorcinol, bi~(4'-hydroxyphenyl)methane (bisphenol F), 2,2-bis-(4'-hydroxyphenyl)propane (bisphenol ~, 2,2-bis(4'-hydroxy-3',5'-dibromophenyl)propane, 1,1,2,2-tetrakis(4'-hydroxyphenyl)ethane, or condensation product~ of phenols with formaldehyde, such as phenol novolaks and cresol novolak~; and also di- or poly(~-methylglycidyl) ethers of the above polyalcohols and polyphenols; polyglycidyl esters and poly(~-methylglycidyl) esters of polyvalent carboxylic acid~, such as phthalic acid, terephthalic acid, tetrahydrophthalic acid and hexahydrophthalic acid; N-glycidyl derlvatives of amines, amides and heterocyclic nitrogen bases, such as N,N-diglycidylani-~27~5~3 line, N,N-diglycldyltoluidine, N,N,N',N'-tetraglycidyl bls(4-amino-phenyl)methane, triglycidylisocyanurate, N,N-diglyoidyl-N,N'-ethyleneurea, N,N'-diglycidyl-5,5-dimethylhydaDtoin, N,N'-dlglycl-dyl-5-isopropylhydantoin, N,N'-diglycidyl-5,5-dimethyl-6-isopropyl-5,6-dihydrouracil.
In general, mixtures of two or more epoxy raslns may also be used in the curabls mixtures of the invention.
Particularly 6uitable are epoxy resin~ with an epoxide content of 5 to 9 equivalents per kg and which are glycidyl ethers, glycidyl esters or N-glycidyl derivative~ of cycloaliphatic compounds or, preferably, of aromatic or heterocyclic compounds.
Preferred epoxy resins are epoxy novolaks, glycidyl derivatives of bisphenols, of aromatic diamines, of aromatic or cycloaliphatic dicarboxylic acids, of hydantoins or of lsocyanuric acid. Part$cu-larly preferred epoxy resins are epoxy phenol novolaks and glycidyl derivatives of bi~phenol A, bisphenol F, hexahydrophthalic acid or 4,4'-diaminodiphenylmethane as well as triglycidyl-bishydantoins or mixtures of such resins. Particularly suitable mixtures o~ epoxy resins as component (a) sre mixtures of an epoxy phenol novolak with glycidyl derivatives of bi~phenol A, bisphenol F, 4,4'-diaminophe-nylmethane or with triglycidyl-bishydantoins, as well as mixtures of a glycidyl derivative o~ bisphenol F with tetrafunctional epoxy resins, e.g. bi3(N,N-diglycidyl-4-aminophenyl)sulfone, bi~(N,N-di-glycityl-4-aminophenyl) ether or 2,2-bis(N',N'-diglycidyl-4'amino-phenyl)propane. A particularly preferred epoxy resin (a) is a mixture of bisphenol F diglycidyl ether and bis(N,N-diglycidyl-4-aminophenyl)methane.
The imidazolides of formula I employed in the mixtures of this invention are known or they can be prepared in a manner known per se. They are suitably prepared by reacting an acid hallde oE
formula II
~2~ 39 ~. 8 ( II) R~ ~
with an imidazole of formula III
H ~\ ~ (III) I
~,1 in wh$ch formulae X i~ chlorine or bromine, and the symbols Rl to R3 are as defined above. Some of these imidazolides and the preparation thexeof are described in the sbove-cited Japanese patent specifica-tion 743 212, German Offenlegungsschrift 32 46 072 and European publi~hed application 0 124 482.
Each of the substituents Rl to R3 independ0ntly of one another may be a branched or, preferably, straight chain alkyl group containing 1 to 12, preferably 1 to 6 and most pr0ferably 1 to 4, carbon atoms.
Fxamples of suitable alkyl groups are dodecyl, decyl, o~tyl, heptyl, butyl, propyl and, most preferably, isopropyl, ethyl or methyl.
If one or more of the sub3tltuents Rl to R3 18 a cycloalkyl group, then the preferred meanings are cyclopentyl and cyclohexyl, ench of which may be ~ubstltuted by one or more Cl-C3alkyl groups. Said groups sre preeerably unsubatituted.
If one or more of the substituents Rl to R3 is an aryl group, then the pseferred meaning~ are phenyl and naphthyl. Tbe subst~tuents R4 to R3 as halogen are iodine or bromine or, preferably, chlorine.
In the mixtures of the present invention, it is preferred to employ imidazolide~ (b) wherein each of the substituents R2, R3, Rs and R7 is hydrogen, the substituent Rl is Cl-C4alkyl or phenyl and each of ~L27~5~
the substituentg R4, R6 and R~ independently of one another is hydrogen, C1-C4alkyl or halogen. Particulnrly preferred imidazolides of formula I are thosa wherein each of R2, R3, Rs and R7 1~ hydro-gen, Rl i8 methyl, ethyl or phenyl snd R6 i8 hydrogen or methyl and each of R4 and RB i8 chlorine or methyl. More particularly preferred imidazolides whlch can be employed in the mixtures of the invention are 1-(2',6'-dichlorobenzoyl)-2-phenylimidazols, 1-(2',4',6'-trime-thylbenzoyl3-2-ethylimidazole, 1-(2',6'-dichlorobenzoyl)-2-methyl-imidazole, 1-(2',4',6'-trimethylbenzoyl)-2-methylimida701e and, mo6t preferably, 1-(2',4',6'-trimethylbenzoyl)-2-phenylimidazole.
The imidazolides of formula I which can be employed in the mixture~
of the invention are highly react~ve hardener3 at elevated tempera-ture, but are stable at room temperature, making longer storaga and proces~ing times possible.
Suitable polysulfone resins (c) are e.g. those containing the recurring element of the formula -A-S0z-wherein A iB 8 divalent aromatic group which may be interrupted by sther oxygen atoms and/or by divalent aliphatlc groups. Preferably, the polysulfone has a heat deflection temperature of at least 150C, as mea3ured in accordance with ASTM Specification D648.
The polysulfones to be employed may be obtalned in ~nown manner e.g.
by heating either (a) a sulEonyl halide uf the formula HAlSOzX or ~b) a mixture of a dlsulfonyl halide of the formula XSOzAISO~X with a sul$onyl halide-free compound of the formula HAzH, in which formulae Al and A2 are identical or different and each is a divalent aromatic group which may be interrupted by ether oxygen atoms and/or by divalent aliphatic groups, and X i8 a chlorine or bromine atom, in an inert solvent and in the pre~ence of a Lewis acid catalyst.
The poly~ulfones prepared in accordance with process (a) contain the recurring element 7~5~
whereas those prepared in sccordance with procQAs (b) contain the recurring element -Al-SOz-A2-S02-Polysulfone resins preferred for use in the mixtures of the present invention are those which contain ether groups in the recurring element but which are free from hydroxyl groups in a side chain.
These are particularly preferred polysulfones containing a recur-ring element of the formula wherein A3 and A4 ars divalent aryl groups, preferably phenylene groups, which may be substituted by chlorine or C1-C4alkyl, e.g.
methyl groups. Such polysulfones can be obtained in a manner known per se by rencting a dialkali metal salt of a dihydric phenol of the formula HOA30H with a bis~monochloroaryl)sulfone of the formula ClA4SOzA4Cl in dimethyl sulfoxide. More preferred polysulfone resins are those containing a recurring element of the formula -OAs-Y-AsOA6-SO2-A6-wherein each of A5 and A6 is a phenylene group which is unsubstitu-ted or substituted by chlorine or Cl-C4alkyl groups, e.g. methyl groups, and Y is a carbon-carbon bond, the group -SO2- or an aliphatic hydrocarbon group, preferably one containing not more than four carbon atoms, such as those of the formula -CH2- or - :-~:7~89 ~ 7 _ 21~89-69~9 Particularly preferred are thermoplastic polysulfone resins contain-ing recurring elements oE Eormula IV
t ~ soz ~ ~ ~ ( IV) .=. .=. .=. '=- n wherein n preferably has an average value of 50 to 120.
Particularly advantageous polysulfones are e.g. those available from the Union Carbide Corporation such as "Polysulfone Udel P1800~"
which according to the manufacturer has a melting point in the range from 350 to 370C, a heat deflection temperature (ASTM Specifica-tion D648) of 175~C and contains per average molecule 50 to 80 recurring elements of formula IV, indicating a molecular weight range of about 22 000 to 35 000.
A further suitable polysulfone is a similar substance available from the Union Carbide Corporation under the name "Polysulfone P2300~"
which according to the manufacturer has a molecular weight range of 30 000 to 50 000, indicating that the substance contains per average molecule about 68 to 113 recurrlng elements of Eormula IV. Also suitable i9 a similar substance available from the Union Carbide Corporation under the name "PolysulEone P3500~" which according to the manufacturer has a molecular weight range lying between that of "Yolysulfone Udel P1800~" and that of "PolysulEone P2300~"; the molecular weight is about 35 000.
Mixtures of t~o or more polysulfones may also be employed as component (c) in the curable mixtures of this :Lnvention.
The epoxy resin (a) and the polysulfone (c) of the mixtures of the present invention are preferably chosen such that the polysulfone is soluble in the epoxy resin and that, after the epoxy resin has been ~ . , ~705~39 cured, two phase3 form which are flnely disper~ed ln each other.
Such sy6tems produce cured products wlth particularly good proper-ties.
Preferred are also those mixtures of the inventlon which, in addition to the above-mentioned components (a) to (c~, contain as component (d) 1 to 12 parts by weight, preferably 2 to 6 part6 by weight, of a finely particulate filler, based on 100 parts by weight of epoxy re6in (a), the pri~ary particles of which flller have an average size of 2 to 100 nm, pref~rably 3 to 30 nm and most prefsr-ably 5 to 15 nm. Particularly suitable fillers (d) are titanium dioxide and, e~pecially, silicon dioxide or aluminium oxide. Such fillers are available e.g. froM the firm Degussa (Switzerland) AG, Zurich, under the name Aerosil~ and Alox C~ and, depending on the product, the primary particles thereof have an average siza of 7 to 12 nm. The addition of the above finely particulate fillers improves in particular the dynamic properties of the mixtures of the invention, which can be determined e.g. in a dynamic alternate bending test on laminates prepared using said mixtures.
It is preferred to employ mixtures of the invention in which the proportions of the component3 (b) and (c) independently of each other are: imidazolide (b) 4 to 12 parts by weight, preferably 5 to 8 parts by weight, and polysulfone (c) 5 to 30 parts by weight, preferably 8 to 15 parts hy weight, each based on 100 parts by weight of the epoxy resin (a).
In the case of mixtures which additionally contain as component (d) a finely particulate filler, lt is preferred to use such mixtures in which the proportion of the polysulfone ~c) iD 10 to 40 parts by weight, preferably 12 to 25 parts by weight, based on 100 parts by weight of the epoxy resin (a).
The mixtures of the invention can be prepared by thoroughly mixing all components or by dissolving them in each other. The indlvidual components may be added in varying sequence. The polysulfone can ~t70S89 _ 9 _ e.g. be dissolved under heat ln the epoxy re~ln, ~nd ~ftor cooling the 601ution to about 120C, the lmidazolide hardener and, iE
desired, the finaly particulate filler or further additives may then be added. If using a finely particulate filler, this i9 preferably fir~t ground down with the epoxy resin in a three-roll mill and the polysulfone is subsequently di6solved in the epoxy resin.
The mixtures o$ the invention have many U~e8 and are suitable for example as casting resins, laminating or impregnating resin3, moulding compositions, sealing compo6itions, embedding or insulating compositions for the electrical industry snd, preferably, as adhesives and as matrix re6in~ for composites, in particular for the preparation of fibra reinforced plastics.
If desired, in particular when using modification agents, the mixtures of the invention may be dissolved in an organic solvent such as toluene, xylene, methyl ethyl ketone or methylene chloride or in a similar solvent or mixture of ~olvent~ customarily employed ln the varnish industry. Such solutions are suitable in particular as impregnating agents or coating agents.
In any phase before curing, customary modification agents may be added to the curable mixtures of the inventlon. Examples of such modification agents are: extenders, fillers, reinforcing agents, pigments, dyes, organic solvents, plasticisers, levelling agents, thixotropic agents, flame retardants or mould release agents.
Examples of extenders, reinforcing agents, fillers snd pigments which may be employed in the curable mixtures of the invention are:
liquid coumarone-indene resins, textile fibres, glass fibres, asbestos fibre~, boron fibres, carbon fibres, polyethylenc powder, polypropylene powder, quartz powder, mineral silicates such as mica, asbestos powder, powdered slate, kaolin, powdered chalk, antimony trioxide, bentone, lithophone, heavy 6par, titanium dioxide, carbon black, graphite, oxide pigments such as iron oxide, or metal powder~ such as aluminium powder or iron powder.
~'~7~ 9 Extenders which may be added when employing the curable mixtures in particular for surface protection are e.g.: silicone6, liquid acrylic re~ins, cellulose acetobutyrate, polyvlnyl butyral, waxas, stearates etc. (some of which are also employed as Moulcl relea~e agents).
Examples of pla~ticisers which may be employed for the modiflcation of the curable mixtures are: dibutyl phthalate, dioctyl phthala~e, dinonyl phthalate, tricresyl phosphate, trixylenyl pho~phate and diphenoxyethyl formal.
The mixtures of the invention are preferably cured by heating them to a temperature in the range from 120 to 250C, in particular from 150 to 200C. The curing may also be carried out in two or more steps in known manner, with tha first curing step being carried out at low temperature and the postcuring at elevated temperature.
If desired, active diluents may be added to the mixtures of the invention in order to reduce the viscosity. Examples of such diluents are: styrene oxide, butyl glycidyl ether, 2,2,4-trimethyl-pentyl glycidyl ether, phenyl glycidyl ether, cresyl glycidyl ether, glycidyl esters of synthet$c, highly branched, mainly tertiary, aliphatic monocarboxylic acids.
Curing accelerators may also be employed for the curing; examples of such accelerators ars: tertiary amines, the salts or quaternary ammonlum compounds thereof, e.g. benzyldimethylamine, 2,4,6-tris-(dimethylamlnomethyl)phenol, l-methylimidazols, 2-ethyl-4-methyl-imidazole, 4-aminopyridins, trLpentylammonium phenolate; or alkali metal alcoholates, e.g. sodium hexane triolate.
The present invention also relates to the use of the mixtures of the invention for the preparation of cured moulded articles, as well as to the use thereof for the preparation of prepregs for fibre reinforced composites or of adhe~ive films. The prepregs and the adhesive films can be prepared in a manner known per se, a.g. by the 1~7~
lmpregnating process in the presence of one of the abov0 solvents or of a halogenated solvent such aA methylene chlorlde, or by the hot melt process.
In general, thc moulding compositions of the invention, while at the same time having high mechanical strength, sre dlstingulshed by relatively high glasD transition temperatures. Particular feature3 of said compositions are their excellent stability to thermal ageing, excsllent fracture toughness and moisture resi~tance.
The invention i9 illustrated in more detail by the following Example~.
The components (a) to (d) employed in the following Examples are as follows:
Epoxy resin 1: An epoxy phenol novolak with an epoxide content of 5.7 equivalents/kg and a viscosity of about 2.0 Pa-s at 52C, which novolak is in the liquid state at room temperature.
Epoxy resin_2. A tetraglycidyl derivative of 4,4'-diaminophenylme-thane with an epoxide content of 7.8 equivalents/kg and a viscosity of about 1.3 Pa~s at 50C.
Epoxy resin 3: A triglycidyl bishydantoin of formula V with an epoxide content of 5.6 equivalents/kg and a ViSCoBity of about 1.3 Pa~s at 80C
CIH3 ,CH3 CH~-/cH2-cH2- ~ CHz- ~H-CHz- ~\ ~ -CHz-C~7CH2 (V).
~ H 2 ~, 0\ Hz ~ ~ ~705~3~
Epoxy resin 4: A blsphenol A diglycidyl ether with an epoxide content of 5.4 equlvalent~/kg and a vi~cosity of 1.0 Pa~6 at 25C.
Epoxy regin 5~ Crystalline bisphenol F diglycidyl ether with an epoxide content of 6.4 equivalents/kg.
Epoxy resin 6: Hexahydrophthalic acid diglycidyl e~ter with an epoxide content of 5.9 equivalents/kg and a viscosity of 0.~ Pa-s at 25C.
Polysulfone 1 Polysulfone Udel Pl800~ (Union Carbide Corporation) with a melting point in the range from 350 to 370C, a heat deflection temperature (in accordance with ASTM D648) of 175C and a molecular welght range of about 22 000 to 35 000.
Imidazolide l: 1-(2',4',6'-Trimethylbenzoyl)-2-phenylimidazole, prepared in accordance with European published application 0 124 482.
Imidazolide 2- 1-(2',6'-dichlorobenzoyl)-2-phenylimidazole, prepared in accordance with German Offenlegung~schrift 32 46 072.
Imidazolide 3. 1-(2',4',6'-Trimethylbenzoyl)-2-ethylimidazole, prepared in accordance with European published appllcation 0 124 482.
Imidazolide 4: 1-(2',6'-dichlorobenzoyl)-2-methyllmidazola, prepared in accordance with German Offenlegungsschrif-t 32 46 072.
Imidazolide 5~ 2'~4',6'-Trlmethylbenzoyl)~2-methylimidazole, prepared in accordance with European published application 0 124 482.
Alox C~. Finely particulate aluminium oxide available from Degussa (Switzerland) AG, Zurich. Average ~ize of the primary particles:
10 nm.
~271~358~:~
Aerosll 300~: Finely part~culate ~ilicoD dioxide avallable from _ . _ Degus6a (Switzerland) AG, Zurich. Average size of the primary particles: 7 nm.
Example 1: 20 g of polysulfone 1 are dlssolved at 200C in 160 g o~
epoxy resin 1. The solution is cooled to 120C and then m~xed with 40 g of epoxy resin 2 and 12 g of imidazolide 1. A proportion of the mixture i9 poured into an Anticorodal mould (200 x 200 x 4 mm) and cured for 2 hour~ st 150C and 2 hours at 180C. A further propor-tion of the mixture i~ used for measuring the fracture toughness by the double tor~ion test following the procedure described in "Journal of Materials Science", 10, 1334 (1975) and 14, 776 (1979).
In this test, two aluminium plate8 [Extrudal 050 AlMgSi 0.5 (200 x 20 x 5 mm)] which have been treated with chromosulfuric acid are cemented with the curable mixture and the bond is cured, as described above, under slight pressure. In the measurement proce-dure, the crack propagation in the bond is determined, i.e. the breaking energy in J/m2 is calculated from the maximum load for the crack propagation.
The following results are obtsined:
flaxural strength (FS) in accordance with ISO 178 ~ 112 MPa edge fibre elongation (EFE) at the moment oE fracture ln accordance with ISO 178 u 6.8 %
glass transitlon temperature (T ) measured with the thermomechanical analyser of the company Mettler AG, Grelfensee, Switzerlsnd ~ 177C
fracture toughness (FT), double torsion te~t ~ 212 Jlm2 Example 2: In accordance wlth the procedure of Example 1, a further test i~ carried out u~ing 200 g of epoxy resin 1, 12 g of imidazo-lide 1 and dlfferent amounts of the polysulfone 1. The following results are obtained (an additional flexural test is carried out after 10 days' storage ln water at 85C):
~7~5~
A~ 5 8 ~ ~5 g Z(J g 25 g FS (MPa) llO 114 115 112 113 FS (after H20) ~MPa~ 102 97 106 107 99 EFE t%) 6.2 6.7 7.1 7.5 6.7 E~E (after H20) (%) 4.9 4.4 5.4 5.7 4~5 FT (J/m2) 91 231 206 150 140 Example 3: In accordance with the procedure of Example l, 48 g of polysulfone l are dissolved in 400 g of epoxy resin 1, and the solution is subsequently mlxed with 40 g of epoxy resin 3 and 24 g of ~midazolide l. A proportion of the mixture is cured a~ described in Example 1. The moulded articles have the following properties:
FS 113 MPa ~FE 5.35 %
FT 276 J¦m2 256 g of the mixture are dis301ved in l50 g of CH2Cl2 for a further test. A unidirectional prepreg is prepared with carbon fibres T 300-50 B (Toray) by the impregnatlng method. The prepreg, which is obtained after the solvent has been distilled off, exhibits a good tack which is pressrved even after storage for several weeks at room temperature. Tho gelling time of the prepreg is 66 minutes at 120C
or 13 minutes at 160C. The prepreg is moulded to a laminate and cured for 2 hours at 150C and 2 hours at l80C. A laminate (60 % by volume of fibres) with a flexural strength of 1290 MPa in the direction of the fibre and 65 MPs across the fibre ig obtained.
After ageing in air for 30 days at 180C, the flexural strength in the direction of the fibre ls l360 MPa and acros~ the fibre is 77 MPa, which demonstrates that the composition of the invention has a high ~tability to ageing.
~L~7~8~
- 15 - 21~89-6~09 Example 4:
a) 48 g of polysulfone 1 are dissolved under heat in 400 g of epo~y resin 1, and the solution is mixed with 24 g oE imida~olide 1.
b) A second mixture is prepared following the procedure indicated under (a) but also admixing 8 g of Alox C~ in a three-roll mill.
c) A further mixture is prepared following the procedure indicated under (b) but using 16 g of Alox C~.
The moulded articles prepared according to Example 1 have the following properties:
a b c T (C) 174 174 174 FS (MPa) 109 112 101 EFE (%) 5.3 5.7 5.1 EFE (after 10 d HzO, 85C)(%) 4.7 4.6 5.3 TAS*, 25C (MPa) 98 95 96 TAS*, 120C (MPa) 50 63 66 FT (J/m2) 209 194 150 * In order to determine the torsion adhesive strength (TAS), aluminium pivots are cemented in accordance with the procedure for measuring with the "Twist-o-meter~" (The Epprecht Company, Instru-ments ~ Controls, Bassersdorf, Switzerland). To this end, the curable mixture i9 heated, with stirring, to 120C until a homogene-ous solution of low vlscosity is obtained. 5 bonds are prepared from the solution after it has cooled to room temperature. These bonds are then cured by heating for 2 hours at 150C and 2 hours at 180C.
Prepregs are prepared from the three mixtures (a), (b) and (c) with a glass fibre weave of 80/20 (mZ weight: 375 g/m2) by the hot melt process. The prepregs are distinguished by good tack. Laminates are prepared from the prepregs (12 layers) in the press (curing: 2 hours at 150 ~ 2 hours at 180~C). In the main fibre direction the .
laminates have a flexural strength of 550-600 MPa. In a dynamic alternate bending tes~ (4-point support of samples 100 x 20 x 4 mm3), the lamlnate (a) under a load of ~ 200 MPa has a working life of 8 x 105 load changss ~drop in tension to 40 % with the max. deformation remalning constant), (b) has a working life of 2S x 105 load changes and (c) a working life of 80 x 10S load changes undsr the same conditions.
Example 5: ~y using a mixture which i8 otherwise ldentical to that in Example 4b but contains, in place of Alox C~, 8 g of Aerosil 300~
which have been treated with a s~lane, ~oulded articles are obtained which have the following properties:
Tg 179C
FS 95 MPa EFE 4.2 %
FT 163 J/m2 Example 6: 30 g of epoxy resin 1 are thoroughly mixed, under heat, with 70 g of epoxy resin 4 and 10 g of polysulfone 1. The mixture is cooled to 120~C and 6 g of imidazolide 2 are admlxed. The mlxture is then processed and cured ln accordance with the procedure of Example 1. The moulded artlcles obtained have the following proper-ties:
FS 97 MPa EFE 5.2 %
g Example 7 50 g of epoxy re~in 2 are thoroughly mixed, under heat, with 50 g of epoxy resin 5 and 15 g of polysulfone 1. The mixture is cooled to about 120C and 6 g of imidazollde 3 are admixed. The mixture i3 then processed and cured ln accordance with the procedure of Example 1. The moulded artlcle~ obtained have the followlng properties:
FS 116 MPa EFE 9.6 %
~g 175C
Example 8: 50 g of epoxy reDin 2 are thoroughly mixed with 50 g of epoxy resin 5 and 2 g of Alox C~ and the mixture is ground down in a three-roll mill for about 20 minutes. The mixture i8 then heatad to about 180C, mixed with 20 g of polysulfone 1 and stirred until the polysulfone has dissol~ed. The solution is cooled to 140C, mixed with 6 g of imidazolide 1 and then processed in accordance wlth the procedure of Example 1:
The following properties are determined:
FS 122 MPa EFE 7.5 %
Tg 179C
FT 196 J/m2 Example 9: By following a procedure analogous to that of Example 8, a polymer con~isting of 30 g of epoxy resin 2, 70 g of epoxy resin 5, 5 g of Alox C~, 24 g of polysulfone 1 and 6 g of imidazolide 1 i~ prepared. The cured polymer has the following properties:
FS 123 MPa EFE 7.3 %
Tg 166C
FT 385 J/m2 Example 10: 60 g of the mixture prepared in accordance with Example 9 conaisting of epoxy resins 2 and 5, Alox G~ and polysul-fone 1 are di~solved :Ln 40 g of methylene chloride, and the solution is ~horoughly mixed with 2.3 g of imidazolide 1.
~o'~ 9 ^ 18 -A glas9 fibre weave 80l20 i9 impregnated with tha solution ualng a doctor knife, and the solvent 18 evaporated off wlth a gentle curren~ of alr. A transparent prepreg with good tack i8 obtained.
The prepreg can be stored for over a month at room temperature without any changes in tack. 14 layers of prepreg are moulded to a laminate plate of 4 mm thlckness and the plate is then ou~ed for
2 hours at 150C and 2 hours at 180C (fibre content: 65.5 %). The laminate plate has a flexural strength of 700 MPa in the direction of the main fibre and of 200 MPa across the main fibre. After storage in water at 71C for 64 days, the laminate has an interlami-nar shear strength of 67 MPa at room temperature and of 34.4 MPa at 71C. The water absorption is 0.8 %.
Example 11:
a) 50 g of epoxy resin 2 are mixed, under heat, wlth 50 g of epoxy resin 5, and the mixture is ground down with 4 g of Alox C~ in a three-roll mill. Subaequently, 12 g of polysulfone 1 are dlsaolved at about 180C ln the resin. The solution i8 cooled to 120DC and 6 g of imidazolide 1 are admixed. The mixture is then processed and cured in accordance with the procedure of Example 1. The moulded artlcles have the following properties:
FS 112 MPa Tg 179C
FT 177 J/m2 b) By using 4 g of Aerosil 300~ in place of Alox C~ and otherwl~e carrying out the same processing and employing the same compositlon as in (a), the following results are obtained:
FS 124 MPa Tg 177C
FT 151 J/m2 ~:7~89 Example 12: Moulded articles are prepared in accordance with the procedure of Example lla but using the 6AmO amount of another imida~olide. The following results are obtatnad:
imidazolide 2 4 5 galling time at 70C 1140 670 160 min.
FS 126 127 100 MPa Tg 174 168 184C
FT 201 204 292 Jlm2 Example 13: Using 50 g of epoxy resin 2 and 50 g of epoxy resin 6 and otherwise carrying out the ssme processing and employing the same composltion as in Example lla, the following reQultg are obtained:
gelling time at 70C 7200 min.
FS 146 MPa EFE 7.1 %
Tg 149 and 170C
FT 305 J/m2 Example 14: Uslng 80 g of epoxy resln 2, 20 g of epoxy resin 6 and 10 g of polysulfone 1 and otherwise carrying out the same processing and employing th~ same composition as in Example 11a, the following result~ are obtained:
gelling time st 70C 2800 min.
FS 131 MPa EFE 7.4 %
Tg 186C
FT 230 J/m2
Example 11:
a) 50 g of epoxy resin 2 are mixed, under heat, wlth 50 g of epoxy resin 5, and the mixture is ground down with 4 g of Alox C~ in a three-roll mill. Subaequently, 12 g of polysulfone 1 are dlsaolved at about 180C ln the resin. The solution i8 cooled to 120DC and 6 g of imidazolide 1 are admixed. The mixture is then processed and cured in accordance with the procedure of Example 1. The moulded artlcles have the following properties:
FS 112 MPa Tg 179C
FT 177 J/m2 b) By using 4 g of Aerosil 300~ in place of Alox C~ and otherwl~e carrying out the same processing and employing the same compositlon as in (a), the following results are obtained:
FS 124 MPa Tg 177C
FT 151 J/m2 ~:7~89 Example 12: Moulded articles are prepared in accordance with the procedure of Example lla but using the 6AmO amount of another imida~olide. The following results are obtatnad:
imidazolide 2 4 5 galling time at 70C 1140 670 160 min.
FS 126 127 100 MPa Tg 174 168 184C
FT 201 204 292 Jlm2 Example 13: Using 50 g of epoxy resin 2 and 50 g of epoxy resin 6 and otherwise carrying out the ssme processing and employing the same composltion as in Example lla, the following reQultg are obtained:
gelling time at 70C 7200 min.
FS 146 MPa EFE 7.1 %
Tg 149 and 170C
FT 305 J/m2 Example 14: Uslng 80 g of epoxy resln 2, 20 g of epoxy resin 6 and 10 g of polysulfone 1 and otherwise carrying out the same processing and employing th~ same composition as in Example 11a, the following result~ are obtained:
gelling time st 70C 2800 min.
FS 131 MPa EFE 7.4 %
Tg 186C
FT 230 J/m2
Claims (16)
1. A storage-stable, heat-curable mixture containing (a) 100 parts by weight of an epoxy resin, (b) 3 to 15 parts by weight of an imidazolide of formula I
(I), wherein each of R1, R2 and R3 independently of one another is hydrogen, C1-C12alkyl, C5-C10cycloalkyl or C6-C10aryl and each of R4 to R8 independently of one another is hydrogen, C1-C12alkyl, halogen, nitro or trifluoromethyl, with the proviso that the substituents R4 and R8 are not simultaneously hydrogen, and (c) 2 to 50 parts by weight of a thermoplastic polysulfone with an average molecular weight of at least 10 000.
(I), wherein each of R1, R2 and R3 independently of one another is hydrogen, C1-C12alkyl, C5-C10cycloalkyl or C6-C10aryl and each of R4 to R8 independently of one another is hydrogen, C1-C12alkyl, halogen, nitro or trifluoromethyl, with the proviso that the substituents R4 and R8 are not simultaneously hydrogen, and (c) 2 to 50 parts by weight of a thermoplastic polysulfone with an average molecular weight of at least 10 000.
2. A mixture according to claim 1, wherein the epoxy resin has an epoxide content of 5 to 9 equivalents/kg and is a glycidyl ether, a glycidyl ester or an N-glycidyl derivative of a cycloaliphatic compound or, preferably, of an aromatic or heterocyclic compound.
3. A mixture according to claim 1, wherein the epoxy resin is an epoxy novolak, or a glycidyl derivative of a bisphenol, of an aromatic or cycloaliphatic dicarboxylic acid, of an aromatic diamine, of a hydantoin or of isocyanuric acid.
4. A mixture according to claim 1, wherein the epoxy resin is an epoxy phenol novolak, a glycidyl derivative of bisphenol A, of bisphenol F, of hexahydrophthalic acid or of 4,4'-diaminodiphenyl-methane, or is a triglycidyl bishydantoin, or a mixture of these resins.
5. A mixture according to claim 1, wherein the epoxy resin is a mixture of bisphenol F diglycidyl ether and bis(N,N-diglycidyl-4-aminophenyl)methane.
6. A mixture according to claim 1, wherein each of the substituents R2, R3, R5 and R7 of the imidazolide is hydrogen, the substituent R1 is C1-C4alkyl or phenyl and each of the substituents R4, R6 and R8 independently of one another is hydrogen, C1-C4alkyl or halogen.
7. A mixture according to claim 6, wherein R1 is methyl, ethyl or phenyl, R6 is hydrogen or methyl and each of R4 and R8 is chlorine or methyl.
8. A mixture according to claim 1, wherein the polysulfone has a heat deflection temperature of at least 150°C.
9. A mixture according to claim 8, wherein the polysulfone contains recurring elements of formula IV
(IV) wherein n preferably has an average value of 50 to 120.
(IV) wherein n preferably has an average value of 50 to 120.
10. A mixture according to claim 9, wherein the polysulfone has a melting point in the range from 350° to 370°C, a heat deflection temperature of 175°C and n has an average value of 50 to 80.
11. A mixture according to claim 1, which additionally contains as component (d) 1 to 12 parts by weight of a finely particulate filler, the primary particles of which filler have an average size of 2 to 100 nm.
12. A mixture according to claim 11, wherein the filler is titanium dioxide, silicon dioxide or aluminium oxide.
13. A mixture according to claim 1, wherein the proportions of the components (b) and (c) independently of each other are: imidazolide (b) 4 to 12 parts by weight and polysulfone (c) 5 to 30 parts by weight, each based on 100 parts by weight of the epoxy resin (a).
14. A mixture according to claim 11, wherein the proportion of the polysulfone (c) is 10 to 40 parts by weight, based on 100 parts by weight of the epoxy resin (a).
15. Use of a mixture according to claim 1 for the preparation of cured moulded articles.
16. Use of a mixture according to claim 1 for the preparation of prepregs for fibre reinforced composites or of adhesive films.
FO 7.3/SZ/co*
FO 7.3/SZ/co*
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH1023/85-2 | 1985-03-07 | ||
| CH102385 | 1985-03-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1270589A true CA1270589A (en) | 1990-06-19 |
Family
ID=4200645
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000503399A Expired CA1270589A (en) | 1985-03-07 | 1986-03-05 | Curable mixtures containing an epoxy resin, an imidazolide and a polysulfone |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0194232B1 (en) |
| JP (1) | JPH068344B2 (en) |
| BR (1) | BR8600953A (en) |
| CA (1) | CA1270589A (en) |
| DE (1) | DE3665723D1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6133357A (en) * | 1997-03-06 | 2000-10-17 | Ticona Gmbh | Mixtures of thermosets and oxidized polyarylene sulfides |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0392348A3 (en) * | 1989-04-14 | 1991-12-27 | Cytec Technology Corp. | Toughened thermosetting structural materials |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1306231A (en) * | 1969-10-24 | 1973-02-07 | ||
| JPS5253973A (en) * | 1975-10-28 | 1977-04-30 | Mitsubishi Electric Corp | Heattresistant preepreg or tape |
| JPS5849718A (en) * | 1981-09-19 | 1983-03-24 | Mitsubishi Electric Corp | Resin material resistant to hot water |
| CH646956A5 (en) * | 1981-12-15 | 1984-12-28 | Ciba Geigy Ag | Imidazolides. |
| EP0124482B1 (en) * | 1983-04-29 | 1989-11-08 | Ciba-Geigy Ag | Imidazolides and their use as curing agents for polyepoxides |
| DE3327823A1 (en) * | 1983-08-02 | 1985-02-21 | Basf Ag, 6700 Ludwigshafen | CURABLE EPOXY RESINS |
| US4579916A (en) * | 1983-11-15 | 1986-04-01 | Ciba-Geigy Corporation | Curable mixtures containing an epoxide resin, an imide and a curing catalyst |
-
1986
- 1986-03-03 EP EP86810106A patent/EP0194232B1/en not_active Expired
- 1986-03-03 DE DE8686810106T patent/DE3665723D1/en not_active Expired
- 1986-03-05 CA CA000503399A patent/CA1270589A/en not_active Expired
- 1986-03-06 BR BR8600953A patent/BR8600953A/en not_active IP Right Cessation
- 1986-03-07 JP JP61050270A patent/JPH068344B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6133357A (en) * | 1997-03-06 | 2000-10-17 | Ticona Gmbh | Mixtures of thermosets and oxidized polyarylene sulfides |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0194232A2 (en) | 1986-09-10 |
| EP0194232A3 (en) | 1987-04-22 |
| EP0194232B1 (en) | 1989-09-20 |
| DE3665723D1 (en) | 1989-10-26 |
| JPS61211330A (en) | 1986-09-19 |
| BR8600953A (en) | 1986-11-18 |
| JPH068344B2 (en) | 1994-02-02 |
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| Date | Code | Title | Description |
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| MKLA | Lapsed |