CA1337088C - Curable epoxy resin mixture - Google Patents
Curable epoxy resin mixtureInfo
- Publication number
- CA1337088C CA1337088C CA 609004 CA609004A CA1337088C CA 1337088 C CA1337088 C CA 1337088C CA 609004 CA609004 CA 609004 CA 609004 A CA609004 A CA 609004A CA 1337088 C CA1337088 C CA 1337088C
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- 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
- C08G59/50—Amines
- C08G59/5033—Amines aromatic
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- 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
- C08G59/20—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 epoxy compounds used
- C08G59/32—Epoxy compounds containing three or more epoxy groups
- C08G59/3227—Compounds containing acyclic nitrogen atoms
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- 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
- C08G59/50—Amines
-
- 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
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Epoxy Resins (AREA)
- Reinforced Plastic Materials (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
Curable mixtures comprising (a) as epoxy resin component, 50 to 100 % by weight of a tetraglycidyl compound of formula I:
( I ), wherein R1, R2, R3 and R4 are each independently of the other a hydrogen atom, a halogen atom or C1-C4alkyl and X is a direct bond, methylene, isopropylidene, 0, C0, S or S02, and 0 to 50% by weight, based on the tetraglycidyl compound of formula I, of a diepoxy compound or of a polyepoxy compound differing from the compound of formula I, (b) as hardener, the diamine of formula II:
( II) in an amount such that there are 0.2 to 1.1 amine hydrogen equivalents per epoxy equivalent, in some cases a diamine of formula III:
(III), wherein R5, R6, R7 and R3 are each independently of the other C1-C4alkyl, no more than two of the substituents R5 to R3 being ethyl, and R9, R10, R11 and R12 are each independently of the other a hydrogen or halogen atom, and in some cases a disecondary diamine of formula IV:
( I ), wherein R1, R2, R3 and R4 are each independently of the other a hydrogen atom, a halogen atom or C1-C4alkyl and X is a direct bond, methylene, isopropylidene, 0, C0, S or S02, and 0 to 50% by weight, based on the tetraglycidyl compound of formula I, of a diepoxy compound or of a polyepoxy compound differing from the compound of formula I, (b) as hardener, the diamine of formula II:
( II) in an amount such that there are 0.2 to 1.1 amine hydrogen equivalents per epoxy equivalent, in some cases a diamine of formula III:
(III), wherein R5, R6, R7 and R3 are each independently of the other C1-C4alkyl, no more than two of the substituents R5 to R3 being ethyl, and R9, R10, R11 and R12 are each independently of the other a hydrogen or halogen atom, and in some cases a disecondary diamine of formula IV:
Description
~ 1 --K-17179/+
Curable epoxy resin mixture The invention relates to a curable mixture containing at least one tetraglycidyl compound of a dinuclear diamine, preferably of diamino-diphenylmethane, bis(3,5-diethyl-4-aminophenyl)methane, preferably together with another alkyl- or halogen-substituted dinuclear diamine or with a particular disecondary diamine, as hardener, and also a thermo-plastic with a glass transition temperature of at least 150C, and to its use, especially as matrix resin for prepregs.
Substituted dinuclear diamines, for example bis(4-amino-3,5-dialkyl-phenyl)methanes or bis(4-amino-3-chloro-5-ethylphenyl)methane, are known as epoxy resin hardeners, for example from British patent 935 606, German Offenlegungsschrift 23 39 237 or European patent document A-O 171 588.
The curable mixtures known hitherto have a low storage stability and are only of limited suitability for the manufacture of prepregs, since these rapidly lose the tackiness desired for more manageable processing.
It is further known that the properties of epoxy resin mixtures can bemodified by the addition of particular thermoplastics. For example, European patent document A-O 108 476 discloses that, when added to curable epoxy mixtures, polyetherimides have an advantageous effect on the viscosity properties of the mixtures. German Offenlegungs-schrift 26 50 019 discloses that moulded materials of greater flexibility are obtained when polyetheramideimide resins are added to curable epoxy resins.
It has now been found that when bis(3,5-diethyl-4-aminophenyl)methane is used as hardener for tetraglycidyl compounds of divalent diamines, mixed with a thermoplastic, moulded materials are obtained which have a surprisingly high elongation and fracture toughness and a high glas transition temperature (Tg). -_ - 2 -When a mixed hardener is used, the mixtures of the invention not only have better processing properties but also have the advantage that the hardener does not crystallize out in the curable mixture, with the result that the tackiness of the prepregs manufactured with the mixtures of the invention is preserved for long periods. The mixtures of the invention can also be used to manufacture good thin films (< 0.1 mm).
The present invention thus relates to a curable epoxy resin mixture comprising (a) as epoxy resin component, 50 to 100 ~0 by weight of a tetraglycidyl compound of formula I: -R\ /R2 (C~2~CH-CHz~-N~ --X--~ ~--N-~CH2-C~-~H2) (I) R3/ \R4 wherein Rl, R2, R3 and R4 are each independently of the other a hydrogen atom, a halogen atom or Cl-C4alkyl and X is a direct bond, methylene, isopropylidene, O, CO, S or SO2, and O to 50 % by weight, based on the tetraglycidyl compound of formula I, of a diepoxy compound or of a polyepoxy compound differing from the compound of formula I, (b) as hardener for the epoxy resin component, the diamine of formula II:
C~Hs /C2Hs HzN ~ - - CHz - ~ /- - NH2 (II) C2Hs CzH5 in an amount such that there are 0.2 to 1.1 amine hydrogen equivalents per epoxy equivalent of epoxy resin component (a), a diamine of formula III:
~ / Rll R7 HzN - ~ ~- - CH2 - ~ ~- - NH2 (III), R6 / \Rl o Rl 2/ \R8 _ _ 3 _ 1 337088 wherein Rs, R6, R7 and R8 are each independently of the other C1-C4alkyl, no more than two of the substituents Rs to R8 being ethyl, and R9, R10, R11 and R12 are each independently of the other a hydrogen or halogen atom, in an amount such that there is 0.0 to 0.8 amine hydrogen equi-valent per epoxy equivalent, and a disecondary diamine of formula IV:
H~ y ~H (IV), wherein Y is a polymethylene radical which is unsubstituted or substi-tuted by C1-C4alkyls and contains at least 4 C atoms in the linear polymethylene chain, and R13 and R14 are each a saturated carbocyclic ring which is unsubstituted or substituted by C1-C4alkyls, or a ring system containing at least 5 ring carbon atoms, in an amount such that there is 0.0 to 0.2 amine hydrogen equivalent per epoxy equivalent, the sum of the amine hydrogen equivalents of the diamines of formulae II, III and IV being not greater than 1.2, (c) 10 to 60 % by weight, based on epoxy resin component (a), of a thermoplastic with a glass transition temperature of at least 150C, and (d) 0 to 20 % by weight, based on epoxy resin component (a), of an amine-or carboxyl-terminated rubber based on butadiene or butadiene-acrylo-nitrile.
In the mixtures of the invention, epoxy resin component (a) preferablyconsists to the extent of up to 100 % by weight of a compound of formula I. Of the compounds of formula I, the tetraglycidyl compound of 4,4'-diaminodiphenylmethane is preferred.
The compounds of formula I are known and some of them are commerciallyavailable.
The following epoxy compounds are examples of possible diepoxy or poly-epoxy compounds which can be present to the extent of up to 50 % by weight in the curable epoxy resin mixtures of the invention:
Polyglycidyl and poly(~-methylglycidyl) esters obtainable by reacting compounds containing two or more carboxylic acid groups per molecule with epichlorohydrin, glycerol dichlorohydrin or ~-methylepichlorohydrin in the presence of alkali. Such polyglycidyl esters can be derived from aliphatic polycarboxylic acids, e.g. oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and dimerized ~r trimerized linoleic acid, from cycloaliphatic poly-carboxylic acids such as tetrahydrophthalic acid, 4-methyltetrahydro-phthalic acid, hexahydrophthalic acid and 4-methylhexa-hydrophthalic acid, or from aromatic polycarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid.
Further examples are polyglycidyl and poly(~-methylglycidyl) ethers obtainable by reacting compounds containing at least two free alcoholic hydroxyl groups and/or phenolic hydroxyl groups per molecu-le with suitable epichlorohydrins under alkaline conditions or in the presence of acid catalysts, followed by treatment with alkali. Such ethers can be derived from acyclic alcohols such as ethylene glycol, diethylene glycol and higher poly(oxyethylene) glycols, propane-1,2-diol and poly(oxy-propylene) glycols, propane-1,3-diol, butane-1,4-diol, poly(oxytetra-methylene) glycols, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylolpropane, pentaerythritol, sorbitol and polyepichlorohydrins, from cycloaliphatic alcohols such as cyclo-hexane-1,3- and -1,4-diol, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane and l,l-bis(hydroxymethyl)cyclohex-3-ene, or from alcohols containing aromatic rings, such as N,N-bis(2-hydroxyethyl)-aniline and p,p'-bis(2-hydroxyethylamino)diphenylmethane. They can also be derived from mononuclear phenols such as resorcinol and hydroquinone, and from polynuclear phenols such as bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-di-bromo-4-hydroxyphenyl)propane and novolaks which are in turn derived from aldehydes such as formaldehyde, acetaldehyde, chloral and furfuraldehyde, and from phenols such as unsubstituted phenol and phenols substituted in the ring by chlorine atoms or alkyl groups containing up to 9 C atoms, such as 4-chlorophenol, 2-methylphenol and 4-tert-butylphenol.
Examples of poly(N-glycidyl) compounds are compounds obtained by the dehydrochlorination of reaction products of epichlorohydrin and amines containing at least two amine hydrogen atoms, such as aniline, n-butyl-~ 5 _ 1 33708~
amine and m-xylylenediamine; triglycidyl isocyanurate and N,N'-diglycidyl derivatives of cyclic alkyleneureas such as ethyleneurea, 1,3-propylene-urea and hydantoins like 5,5-dimethylhydantoin.
Examples of poly(S-glycidyl) compounds are the S-glycidyl derivatives of dithiols such as ethane-1,2-dithiol and bis(4-mercaptomethylphenyl) ether.
It is also possible to use epoxy resins in which the 1,2-epoxy groups are bonded to different heteroatoms, e.g. the N,N,O-triglycidyl derivative of 4-aminophenol, the glycidyl ether glycidyl ester of salicylic acid, N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethyl-hydantoin~and 2-glycidyloxy-1,3-bis(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane.
Said epoxy compounds are known and some of them are commercially available.
The curable mixtures of the invention preferably contain, as hardener (b), a mixture of the diamine of formula II and a diamine of formula III or IV. The hardener (b) can also consist of a mixture of the diamine of formula II, a diamine of formula III and a diamine of formula IV, the sum of the amine hydrogen equivalents of the diamines of formulae II, III and IV being not greater than 1.2.
In particular, the hardener (b) consists of a mixture of the diamine of formula II and a diamine of formula III, it being preferred to use a mixing ratio of 1:1 to 3:1.
As mentioned at the outset, the diamines of formulae II and III are known. In formula III, Rs, R~, R7 and R8 are preferably each independent-ly of the other methyl, ethyl, propyl or isopropyl, in particular each independently of the other methyl or isopropyl, and R9, Rl, Rll and Rl2 are each a hydrogen atom.
~_ -- 6 --Examples of suitable compounds of formula III are bis( 3-methyl-4-amino-5-ethylphenyl)methane, bis( 3-methyl-4-amino-5-isopropylphenyl)methane, bis(3,5-diisopropyl-4-aminophenyl)methane, bis(2-chloro-3,5-diethyl-4-aminophenyl)methane, bis( 3-ethyl-4-amino-5-sec-butylphenyl)methane and bis(2,6-dichloro-3,5-diethyl-4-aminophenyl)methane.
An especially preferred hardener (b) is a mixture of the diamine of formula II and a diamine of formula IV. The diamines of formula IV and the processes for their preparation are known from German patent 17 70 539. As diamines of formula IV, it is preferred to use those in which Y in said formula is an unsubstituted polymethylene radical containing 4 to 8 C atoms and R1 3 and R1 4 are each cyclopentyl or cyclohexyl.
Examples of suitable compounds of formula IV are N,N'-di(cyclopentyl)-hexamethylenediamine, N,N'-di(cyclohexyl)-2,2,4-trimethylhexamethylene-diamine, N,N'-di(cyclohexyl)-2,4,4-trimethylhexamethylenediamine and, in particular, N,N'-di(cyclohexyl)hexamethylenediamine.
Thermoplastics (c) which can be used in the curable mixtures of sub-stances of the invention are all known polymers which have a sufficiently high glass transition temperature (Tg), i.e. Tg > 150C, and are miscible with the epoxy resin hardener system in question. On account of their properties, polysulfones, polyethersulfones, polyimides or polyether-imides are particularly suitable as thermoplastics, especially poly-sulfones and polyetherimides. Thermoplastics with a glass transition temperature in the range from 180 to 350C, in particular 190 to 250C, are especially preferred for this purpose. When polyetherimides are used, polymers with a Tg in the range from 220 to 250C are especially pre-ferred; when polyimides are used, those with a Tg in the range from 280 to 340C are especially preferred.
Examples of suitable polysulfones used as thermoplastic (c) are compounds containing the repeat unit of the formula _ - 7 -wherein A is a divalent aromatic group which may be interrupted by ether oxygen atoms and/or divalent aliphatic groups.
The polysulfones to be used can be obtained in known manner, e.g. by heating either (1) a sulfonyl halide of the formula HAlSO2X or (2) a mixture of a disulfonyl halide of the formula XSO2A1SO2X with a compound of the formula HA2H which is free from sulfonyl halide, wherein Al and A2 are identical or different and are each a divalent aromatic group which may be interrupted by ether oxygen atoms and/or divalent aliphatic groups, and X is a chlorine or bromine atom, in an inert solvent in the presence of a Lewis acid catalyst. The polysulfones prepared by process (1) contain the repeat unit --Al--SOz--, whereas the polysulfones prepared by process (2) contain the repeat unit - Al - SOz - Az - SOz - -Polysulfone resins which are preferably used in the mixtures of the invention are those which contain ether groups in the repeat unit, but which are free from lateral hydroxyl groups. Said polysulfones are in particular those containing a repeat unit of the formula - OA30A4SOzA4 - , wherein A3 and A4 are divalent arylene groups, especially phenylene groups, which can be substituted by chlorine or Cl-C4alkyl, for example methyl groups. Such polysulfones are obtained in a manner known per se by reacting 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 preferably, the polysulfone resins used are those containing a repeat unit of the formula - OAs - Yl - AsOA6 - SO2 - A6 -wherein As and A6 are each a phenylene group which is unsubstituted or substituted by chlorine or C1-C4alkyl groups, e.g. methyl groups, and Y
is a carbon-carbon bond, the -SOz- group or an aliphatic hydrocarbon group, especially one containing no more than four carbon atoms, e.g. a hydrocarbon group of the formula - CH2 - or ~
It is especially preferred to use thermoplastic polysulfone resins containing repeat units of formula V:
_ C~H3 _ _ _ --¢~ SO2~ -~ (V), .=. .=. .=. .=.
H3 -n wherein n preferably has an average value of 50-120.
Examples of particularly advantageous polysulfones are the compounds obtainable 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, has a deflection temperature under load (ASTM specification D648) of 175C and contains an average of 50-80 repeat units of formula V per molecule, it being possible to assume a molecular weight range of about 22,000-35,000.
Also suitable are a similar substance obtainable from the Union CarbideCorporation under the name "Polysulfone P2300", which, according to the manufacturer, has a molecular weight range of 30,000-50,000, from which it can be assumed that the substance contains an average of about 68-113 repeat units of formula v per molecule, and a similar substance obtainable from the Union Carbide Corporation under the name "Poly-sulfone P3500", which, according to the manufacturer, has a molecular weight range between that of Polysulfone Udel P1800 and that of "Polysulfone P2300", the molecular weight being ca. 35,000.
_ ~,:
According to the invention, it is also possible to use mixtures of two or more thermoplastics as component (c).
Particularly suitable as thermoplastics (c) are polyimides such as - polyimides containing phenylindane units, e.g. those disclosed in US
patent 3 856 752 and in European patent document A 92 524, especially those with a glass transition temperature of about 305C and an average molecular weight of ca. 65,000, e.g. Matrimid~ 5218 from Ciba-Geigy, - homopolyimides and copolyimides of at least one aromatic tetracar-boxylic acid and at least one aromatic diamine, e.g. those disclosed in US patent 4 629 777, and - homopolyimides and copolyimides such as those disclosed -in European patent documents A 162 017 and A 181 837 and in US patent 4 629 685.
Other preferred thermoplastics (c) are polyetherimides such as the products commercially available from General Electric under the name Ultem~ (e.g. Ultem~ 1000). Other preferred thermoplastics are polyether-sulfones such as Victrex~ PES 100 P from ICI or Udel P 1800 from Union Carbide.
Examples of suitable polyamide-imides are the compounds disclosed in US patents 3 894 114, 3 948 835, 3 926 911 and 3 950 408.
The amine- or carboxyl-terminated rubbers based on butadiene or buta-diene-acrylonitrile, which may be present as component (d) in the curable mixtures of the invention, are known and are commercially available from B.F. Goodrich under the name Hycar~, which are reactive liquid polymers.
The amine-terminated (AT) or carboxyl-terminated (CT) reactive liquid polymers are homopolymers of butadiene (B) or copolymers of butadiene and acrylonitrile (BN). In some of the products obtainable, additional reactive groups, for example vinyl or carboxyl groups, are distributed throughout the polymer chain.
For the carboxyl-terminated butadiene-acrylonitrile rubber (CTBN), for example, the structure can be represented in simplified form as follows:
~ ~37088 HOOC ~ CH2-CH=CH-CH2~ CHz-~1l) ] COOH , wherein x is a number from 1 to 10, preferably 2-7, y is a number from 1 to 5, preferably 1-3, and z is a number from 1 to 30, prefer-ably 5-15.
As component (d), the mixtures of the invention preferably contain an amine-terminated rubber based on butadiene or butadiene-acrylonitrile, especially an amine-terminated rubber based on butadiene.
The mixtures of the invention can be prepared by thoroughly mixing all the components or dissolving them in one another, it being possible for the individual components to be added in different orders. For example, the thermoplastic can be dissolved in the epoxy resin, with heating, and the other ingredients can be added after the solution has cooled. Another possible method is to prepare a solution of the thermoplastic in an inert solvent, e.g. in methylene chloride, and to mix this solution with the mixture of epoxy resin hardeners.
The mixtures of the invention have many possible uses and are suitable for example as casting resins, laminating or impregnating resins, moulding compounds, sealing compounds and potting and insulating com-pounds in electrical engineering, and preferably as adhesives and as matrix resins for composites, especially for the manufacture of prepregs for fibre-reinforced plastics.
If desired, especially when modifiers are also used, the mixtures of the invention can be dissolved in an organic solvent such as toluene, xylene, methyl ethyl ketone, methylene chloride or a similar solvent or solvent mixture conventionally used in the paint industry. Such solutions are particularly suitable as impregnating or coating compositions.
Conventional modifiers, such as extenders, fillers and reinforcing agents, pigments, dyes, organic solvents, plasticizers, levelling agents, thixotropic agents, flame retardants or mould release agents, can also be added to the curable mixtures of the invention, before curing, in any ~_ 11 - 1 337~88 phase. Examples of extenders, reinforcing agents, fillers and pigments which can be used in the curable mixtures of the invention are: liquid coumarone-indene resins, textile fibres, glass fibres, asbestos fibres, boron fibres, carbon fibres, polyethylene powder, polypropylene powder, quartz powder, mineral silicates such as mica, asbestos powder, ground shale and kaolin, powdered chalk, antimony trioxide, bentones, litho-pones, barite, titanium dioxide, carbon black, graphite, oxide pigments such as iron oxide, or metal powders such as aluminium powder or iron powder. If the mixtures of the invention are used for the manufacture of prepregs, it is particularly desirable to add short fibres.
Examples of levelling agents which can be added when the curable mixtures are used especially for surface protection are silicones, liquid acrylic resins, cellulose acetobutyrate, polyvinylbutyral, waxes, stearates etc.
(some of which are also used as mould release agents).
Examples of plasticizers which can be used to modify the curable mixtures are dibutyl, dioctyl and dinonyl phthalate, tricresyl phosphate, tri-xylenyl phosphate and diphenoxyethylformal.
The mixtures of the invention are preferably cured by being heated to atemperature in the range from 120 to 250C, especially 160 to 220C.
Curing can also be carried out in two or more stages, in known manner, the first curing stage being carried out at a low temperature and the postcure at a higher temperature.
If desired, active diluents, e.g. the diglycidyl ether of neopentyl glycol, butanediol or hexanediol, can be added to the curable mixtures in order to lower the viscosity.
The present invention further relates to the use of the mixtures of theinvention for the manufacture of cured moulded materials and to their use for the manufacture of prepregs for fibre-reinforced composites. The prepregs can be manufactured in a manner known per se, e.g. by the impregnation process in the presence of one of the above-mentioned solvents or a halogenated solvent such as methylene chloride, or by the hot melt process.
_ - 12 ~ 1 337088 The moulded materials of the invention are distinguished in general by high glass transition temperatures in combination with good mechanical strength properties, and especially by an excellent fracture toughness and a very high extensibility.
In the Examples, the following compounds are used as epoxy resin, thermoplastic or rubber:
Epoxy resin A: N,N,N',N'-Tetraglycidyl derivative of 4,4'-diaminodi-phenylmethane with an epoxy content of 7.8 equivalents/kg and a viscosity of 13,500 mPa-s at 50C.
Epoxy resin B: N,N,N',N'-Tetraglycidyl derivative of 4,4'-diaminodi-phenylmethane with an epoxy content of 9.1 equivalents/kg and a viscosity of 5000 mPa-s at 50C.
Epoxy resin C: Bisphenol A diglycidyl ether with an epoxy content of 5.2 to 5.4 equivalents/kg and a viscosity of 103-123 MPa-s at 25C.
Epoxy resin D: Bisphenol F diglycidyl ether with an epoxy content of 5.5 to 5.9 equivalents/kg and a viscosity of 3000-10,000 MPa-s at 25C.
Epoxy resin E: Phenolic novolak epoxy resin with an epoxy content of 5.6 to 5.8 equivalents/kg and a melting viscosity of 1100-1700 MPa-s at 50C.
Epoxy resin F: N,N-Diglycidyl-p-aminophenol glycidyl ether (ERLA~ 0510).
Polysulfone I: Polysulfone Udel P1800~ (Union Carbide Corporation) with a melting point in the range from 350 to 370C, a deflection temperature under load (according to ASTM D 648) of 175C, a glass transition temperature of 200C and a molecular weight range of ca. 22,000-23,000.
Polyetherimide I: Polyetherimide Ultem~ 1000 (General Electric) with a glass transition temperature of 219C and containing the repeat struc-tural unit of the formula `~ 1 337088 ~ C
~ CH3 / ~ / \ ~-\
Polyethersulfone I: Polyethersulfone Victrex~) P 5003 (ICI) with a deflec-tion temperature under load (according to IS0 75) of 215C and containing the repeat structural unit of the formula ~---SO2~
Example 1: 15 g of polysulfone I are dissolved at 150C in 128 g (1 epoxy equivalent) of epoxy resin A. 71 g (0.9 amine hydrogen equivalent) of bis(3,5-diethyl-4-aminophenyl)methane are then mixed with the solution and the mixture is cooled to about 130C. 10 g (0.07 amine hydrogen equivalent) of N,N'-dicyclohexyl-1,6-diaminohexane are mixed with this mixture. The resin mixture is viscous at room temperature and still tacky after storage for 5 weeks at room temperature. The mixture is freed from included air bubbles and poured into a 4 mm thick aluminium (Anticorodal) mould. Mouldings having the following properties are obtained after a curing time of 2 hours at 160C and 2 hours at 180C:
Glass transition temperature (Tg, measured with a Mettler "TMA 3000"
instrument as the peak maximum of the penetration speed) = 198C
Flexural strength (FS) according to IS0 178 at 23C = 131 MPa Flexural elongation (FE) according to IS0 178 = 11 %.
Example 2: A resin mixture is prepared as in Example 1, this time withthe addition of 77 g (1.0 equivalent) of bis(3,5-diethyl-4-aminophenyl)-methane and no other diamine. The mixture loses its tackiness after storage for 6 days at room temperature. The mouldings cured under identical conditions have the following properties:
- 14 - ~ 8 Tg = 203C
FS = 133 MPa FE = 13.2 %.
Example 3: 40 g of polyetherimide I are dissolved in 200 g of methylenechloride at room temperature and mixed thoroughly with 128 g (1 equiva-lent) of epoxy resin A. The solvent is evaporated off with stirring and heating to 150C. 71 g (0.9 equivalent) of bis(3,5-diethyl-4-amino-phenyl)methane and 10 g (0.07 equivalent) of N,N'-dicyclohexyl-1,6-di-aminohexane are added as in Example 1. The curable mixture has a very high viscosity at room temperature and still exhibits a good tackiness even after storage for 20 days. In the DSC diagram with a heating rate of 10/min, the curing reaction reaches the ~x; ~ exothermicity (T max) at 235C. The viscosity (~) is 7600 mPa-s at 120C. Mouldings having the following properties are obtained after a curing time of 2 hours at 160C
and 2 hours at 200C:
Tg = 208C
FS = 142 MPa FE = 10.1 %.
Example 4: Example 3 is repeated, this time with a mixture of 20 g of polysulfone I and 20 g of polyetherimide I being used instead of 40 g of polyetherimide I. The mouldings produced under identical curing condi-tions have the following properties:
T max (DSC) = 237C
= 4800 mPa-s Tg = 139 MPa FE = 9.0 %.
Example 5: Example 3 is repeated and 3 g of the amine-terminated butyl-nitrile rubber Hycar~ ATBN 1300 x 16 (Goodrich) are also added to the curable mixture. The mouldings produced under identical curing conditions have the following properties:
T max (DSC) = 234C
(120C) = 7000 mPa-s ~~ - 15 - 1 3 3 7 0 8 8 FS = 141 MPa FE = 12.9 %.
Example 6: 35 g of polyetherimide I are dissolved in 200 ml of methylene chloride. 110 g (1 equivalent) of epoxy resin B are then added and the methylene chloride is distilled off by heating, with stirring. The mixture is then heated to about 150C and 55 g (0.7 equivalent) of bis(3,5-diethyl-4-aminophenyl)methane, 24 g (0.3 equivalent) of bis(3-methyl-4-amino-5-isopropylphenyl)methane and 3 g of Hycar~ ATBN 1300 x 16 are dissolved therein. Mouldings produced from this mixture as in Example 1 have the following properties:
Tg = 197C
FS = 148 MPa FE = 11.6 %.
The uncured resin mixture has a viscosity of 2550 mPa-s at 120C and a viscosity of 52,000 mPa-s at 70C and can easily be processed, for example from a solution in methylene chloride, to give thin films (0.1 mm), as used for the manufacture of prepregs. The films exhibit a good tackiness and are still tacky and transparent even after storage for several days, i.e. the hardener has not crystallized out in the resin.
Example 7: A curable mixture consisting of 60 g (0.47 equivalent) of epoxy resin A, 40 g (0.21 equivalent) of epoxy resin C, 31.8 g (0.41 equivalent) of bis(3,5-diethyl-4-aminophenyl)methane, 15.2 g (0.24 equivalent) of bis(3-ethyl-5-methyl-4-aminophenyl)methane and 20 g of polysulfone I is prepared as in Example 1. The mixture can be pro-cessed by melting to give a film of good tackiness. After storage for several days, the film shows no signs of recrystallization. The mouldings cured under such conditions have the following properties:
Tg = 206C
FS = 130 MPa FE = 11.3 %.
~ - 16 - 1 33708~
Example 8: Another mixture is prepared from 80 g of epoxy resin A, 20 g of epoxy resin D, 5 g of a carboxyl-terminated rubber based on butadiene and acrylonitrile (= Hycar~ CTBN 1300 x 13), 43 g of bis(3,5-diethyl-4-aminophenyl)methane (hardener II), 11.5 g of bis(3-methyl-4-amino-5-iso-propylphenyl)methane (hardener I), 10 g of polysulfone I and 15 g of polyetherimide I. Before the thermoplastic and amine are added, the carboxyl-terminated rubber is prereacted for 1 hour at 150C. The film obtained shows no signs of recrystallization. The cured moulding has the following properties:
Tg = 205C
FS = 117 MPa FE = 5.1 %.
Example 9: Tacky films which also do not crystallize out are obtained with the following mixtures:
A B
Epoxy resin A 80 g (0.63 equiv.) 80 g (0.63 equiv.) Epoxy resin E 20 g (0.11 equiv.) 0 Epoxy resin F 0 20 g (0.21 equiv.) Hardener II 43 g (0.56 equiv.) 43 g (0.56 equiv.) Hardener I 11.5 g (0.15 equiv.) 0 Hardener III*) 0 14 g (0.15 equiv.) Polyethersulfone I 20 g 20 g *) Hardener III = bis(3,5-diethyl-4-amino-6-chlorophenyl)methane The mouldings cured as in Example 1 have the following properties:
A B
Tg [C] 208 213 FS [MPa] 138 145 FE [%] 8.4 10.2.
Example 10: Production of carbon fibre laminates:
a) With the mixture according to Example 3, a unidirectional prepreg is produced by melting ("T-300 6K" carbon fibre from TORAY). A unidirec-tional laminate is produced in an autoclave by the vacuum bag technique (heating by 3C/min up to 180C, followed by 3 hours at 180C and 7 bar _ - 17 - 1 3 3 7 0 8 8 pressure). The laminates exhibit an interlaminar shear strength (ILSS
according to DIN 29 971) of 94 MPa at 23C and of 56 MPa at 120C. After storage in water for 14 days at 70C, the ILSS is 83 MPa at 23C and 44 MPa at 120C.
b) A laminate produced from a mixture according to Example 6 has the following properties:
Tg = 219C
ILSS at 23C = 81 MPa ILSS at 120C = 60 MPa ILSS at 23C = 88 MPa } after storage in water ILSS at 120C = 51 MPa for 14 days at 70C
FS at 0C = 1870 MPa FS at 90C = 91 MPa Water absorption = 0.5 %.
Curable epoxy resin mixture The invention relates to a curable mixture containing at least one tetraglycidyl compound of a dinuclear diamine, preferably of diamino-diphenylmethane, bis(3,5-diethyl-4-aminophenyl)methane, preferably together with another alkyl- or halogen-substituted dinuclear diamine or with a particular disecondary diamine, as hardener, and also a thermo-plastic with a glass transition temperature of at least 150C, and to its use, especially as matrix resin for prepregs.
Substituted dinuclear diamines, for example bis(4-amino-3,5-dialkyl-phenyl)methanes or bis(4-amino-3-chloro-5-ethylphenyl)methane, are known as epoxy resin hardeners, for example from British patent 935 606, German Offenlegungsschrift 23 39 237 or European patent document A-O 171 588.
The curable mixtures known hitherto have a low storage stability and are only of limited suitability for the manufacture of prepregs, since these rapidly lose the tackiness desired for more manageable processing.
It is further known that the properties of epoxy resin mixtures can bemodified by the addition of particular thermoplastics. For example, European patent document A-O 108 476 discloses that, when added to curable epoxy mixtures, polyetherimides have an advantageous effect on the viscosity properties of the mixtures. German Offenlegungs-schrift 26 50 019 discloses that moulded materials of greater flexibility are obtained when polyetheramideimide resins are added to curable epoxy resins.
It has now been found that when bis(3,5-diethyl-4-aminophenyl)methane is used as hardener for tetraglycidyl compounds of divalent diamines, mixed with a thermoplastic, moulded materials are obtained which have a surprisingly high elongation and fracture toughness and a high glas transition temperature (Tg). -_ - 2 -When a mixed hardener is used, the mixtures of the invention not only have better processing properties but also have the advantage that the hardener does not crystallize out in the curable mixture, with the result that the tackiness of the prepregs manufactured with the mixtures of the invention is preserved for long periods. The mixtures of the invention can also be used to manufacture good thin films (< 0.1 mm).
The present invention thus relates to a curable epoxy resin mixture comprising (a) as epoxy resin component, 50 to 100 ~0 by weight of a tetraglycidyl compound of formula I: -R\ /R2 (C~2~CH-CHz~-N~ --X--~ ~--N-~CH2-C~-~H2) (I) R3/ \R4 wherein Rl, R2, R3 and R4 are each independently of the other a hydrogen atom, a halogen atom or Cl-C4alkyl and X is a direct bond, methylene, isopropylidene, O, CO, S or SO2, and O to 50 % by weight, based on the tetraglycidyl compound of formula I, of a diepoxy compound or of a polyepoxy compound differing from the compound of formula I, (b) as hardener for the epoxy resin component, the diamine of formula II:
C~Hs /C2Hs HzN ~ - - CHz - ~ /- - NH2 (II) C2Hs CzH5 in an amount such that there are 0.2 to 1.1 amine hydrogen equivalents per epoxy equivalent of epoxy resin component (a), a diamine of formula III:
~ / Rll R7 HzN - ~ ~- - CH2 - ~ ~- - NH2 (III), R6 / \Rl o Rl 2/ \R8 _ _ 3 _ 1 337088 wherein Rs, R6, R7 and R8 are each independently of the other C1-C4alkyl, no more than two of the substituents Rs to R8 being ethyl, and R9, R10, R11 and R12 are each independently of the other a hydrogen or halogen atom, in an amount such that there is 0.0 to 0.8 amine hydrogen equi-valent per epoxy equivalent, and a disecondary diamine of formula IV:
H~ y ~H (IV), wherein Y is a polymethylene radical which is unsubstituted or substi-tuted by C1-C4alkyls and contains at least 4 C atoms in the linear polymethylene chain, and R13 and R14 are each a saturated carbocyclic ring which is unsubstituted or substituted by C1-C4alkyls, or a ring system containing at least 5 ring carbon atoms, in an amount such that there is 0.0 to 0.2 amine hydrogen equivalent per epoxy equivalent, the sum of the amine hydrogen equivalents of the diamines of formulae II, III and IV being not greater than 1.2, (c) 10 to 60 % by weight, based on epoxy resin component (a), of a thermoplastic with a glass transition temperature of at least 150C, and (d) 0 to 20 % by weight, based on epoxy resin component (a), of an amine-or carboxyl-terminated rubber based on butadiene or butadiene-acrylo-nitrile.
In the mixtures of the invention, epoxy resin component (a) preferablyconsists to the extent of up to 100 % by weight of a compound of formula I. Of the compounds of formula I, the tetraglycidyl compound of 4,4'-diaminodiphenylmethane is preferred.
The compounds of formula I are known and some of them are commerciallyavailable.
The following epoxy compounds are examples of possible diepoxy or poly-epoxy compounds which can be present to the extent of up to 50 % by weight in the curable epoxy resin mixtures of the invention:
Polyglycidyl and poly(~-methylglycidyl) esters obtainable by reacting compounds containing two or more carboxylic acid groups per molecule with epichlorohydrin, glycerol dichlorohydrin or ~-methylepichlorohydrin in the presence of alkali. Such polyglycidyl esters can be derived from aliphatic polycarboxylic acids, e.g. oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid and dimerized ~r trimerized linoleic acid, from cycloaliphatic poly-carboxylic acids such as tetrahydrophthalic acid, 4-methyltetrahydro-phthalic acid, hexahydrophthalic acid and 4-methylhexa-hydrophthalic acid, or from aromatic polycarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid.
Further examples are polyglycidyl and poly(~-methylglycidyl) ethers obtainable by reacting compounds containing at least two free alcoholic hydroxyl groups and/or phenolic hydroxyl groups per molecu-le with suitable epichlorohydrins under alkaline conditions or in the presence of acid catalysts, followed by treatment with alkali. Such ethers can be derived from acyclic alcohols such as ethylene glycol, diethylene glycol and higher poly(oxyethylene) glycols, propane-1,2-diol and poly(oxy-propylene) glycols, propane-1,3-diol, butane-1,4-diol, poly(oxytetra-methylene) glycols, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerol, 1,1,1-trimethylolpropane, pentaerythritol, sorbitol and polyepichlorohydrins, from cycloaliphatic alcohols such as cyclo-hexane-1,3- and -1,4-diol, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane and l,l-bis(hydroxymethyl)cyclohex-3-ene, or from alcohols containing aromatic rings, such as N,N-bis(2-hydroxyethyl)-aniline and p,p'-bis(2-hydroxyethylamino)diphenylmethane. They can also be derived from mononuclear phenols such as resorcinol and hydroquinone, and from polynuclear phenols such as bis(4-hydroxyphenyl)methane, 4,4'-dihydroxybiphenyl, bis(4-hydroxyphenyl)sulfone, 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3,5-di-bromo-4-hydroxyphenyl)propane and novolaks which are in turn derived from aldehydes such as formaldehyde, acetaldehyde, chloral and furfuraldehyde, and from phenols such as unsubstituted phenol and phenols substituted in the ring by chlorine atoms or alkyl groups containing up to 9 C atoms, such as 4-chlorophenol, 2-methylphenol and 4-tert-butylphenol.
Examples of poly(N-glycidyl) compounds are compounds obtained by the dehydrochlorination of reaction products of epichlorohydrin and amines containing at least two amine hydrogen atoms, such as aniline, n-butyl-~ 5 _ 1 33708~
amine and m-xylylenediamine; triglycidyl isocyanurate and N,N'-diglycidyl derivatives of cyclic alkyleneureas such as ethyleneurea, 1,3-propylene-urea and hydantoins like 5,5-dimethylhydantoin.
Examples of poly(S-glycidyl) compounds are the S-glycidyl derivatives of dithiols such as ethane-1,2-dithiol and bis(4-mercaptomethylphenyl) ether.
It is also possible to use epoxy resins in which the 1,2-epoxy groups are bonded to different heteroatoms, e.g. the N,N,O-triglycidyl derivative of 4-aminophenol, the glycidyl ether glycidyl ester of salicylic acid, N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethyl-hydantoin~and 2-glycidyloxy-1,3-bis(5,5-dimethyl-1-glycidylhydantoin-3-yl)propane.
Said epoxy compounds are known and some of them are commercially available.
The curable mixtures of the invention preferably contain, as hardener (b), a mixture of the diamine of formula II and a diamine of formula III or IV. The hardener (b) can also consist of a mixture of the diamine of formula II, a diamine of formula III and a diamine of formula IV, the sum of the amine hydrogen equivalents of the diamines of formulae II, III and IV being not greater than 1.2.
In particular, the hardener (b) consists of a mixture of the diamine of formula II and a diamine of formula III, it being preferred to use a mixing ratio of 1:1 to 3:1.
As mentioned at the outset, the diamines of formulae II and III are known. In formula III, Rs, R~, R7 and R8 are preferably each independent-ly of the other methyl, ethyl, propyl or isopropyl, in particular each independently of the other methyl or isopropyl, and R9, Rl, Rll and Rl2 are each a hydrogen atom.
~_ -- 6 --Examples of suitable compounds of formula III are bis( 3-methyl-4-amino-5-ethylphenyl)methane, bis( 3-methyl-4-amino-5-isopropylphenyl)methane, bis(3,5-diisopropyl-4-aminophenyl)methane, bis(2-chloro-3,5-diethyl-4-aminophenyl)methane, bis( 3-ethyl-4-amino-5-sec-butylphenyl)methane and bis(2,6-dichloro-3,5-diethyl-4-aminophenyl)methane.
An especially preferred hardener (b) is a mixture of the diamine of formula II and a diamine of formula IV. The diamines of formula IV and the processes for their preparation are known from German patent 17 70 539. As diamines of formula IV, it is preferred to use those in which Y in said formula is an unsubstituted polymethylene radical containing 4 to 8 C atoms and R1 3 and R1 4 are each cyclopentyl or cyclohexyl.
Examples of suitable compounds of formula IV are N,N'-di(cyclopentyl)-hexamethylenediamine, N,N'-di(cyclohexyl)-2,2,4-trimethylhexamethylene-diamine, N,N'-di(cyclohexyl)-2,4,4-trimethylhexamethylenediamine and, in particular, N,N'-di(cyclohexyl)hexamethylenediamine.
Thermoplastics (c) which can be used in the curable mixtures of sub-stances of the invention are all known polymers which have a sufficiently high glass transition temperature (Tg), i.e. Tg > 150C, and are miscible with the epoxy resin hardener system in question. On account of their properties, polysulfones, polyethersulfones, polyimides or polyether-imides are particularly suitable as thermoplastics, especially poly-sulfones and polyetherimides. Thermoplastics with a glass transition temperature in the range from 180 to 350C, in particular 190 to 250C, are especially preferred for this purpose. When polyetherimides are used, polymers with a Tg in the range from 220 to 250C are especially pre-ferred; when polyimides are used, those with a Tg in the range from 280 to 340C are especially preferred.
Examples of suitable polysulfones used as thermoplastic (c) are compounds containing the repeat unit of the formula _ - 7 -wherein A is a divalent aromatic group which may be interrupted by ether oxygen atoms and/or divalent aliphatic groups.
The polysulfones to be used can be obtained in known manner, e.g. by heating either (1) a sulfonyl halide of the formula HAlSO2X or (2) a mixture of a disulfonyl halide of the formula XSO2A1SO2X with a compound of the formula HA2H which is free from sulfonyl halide, wherein Al and A2 are identical or different and are each a divalent aromatic group which may be interrupted by ether oxygen atoms and/or divalent aliphatic groups, and X is a chlorine or bromine atom, in an inert solvent in the presence of a Lewis acid catalyst. The polysulfones prepared by process (1) contain the repeat unit --Al--SOz--, whereas the polysulfones prepared by process (2) contain the repeat unit - Al - SOz - Az - SOz - -Polysulfone resins which are preferably used in the mixtures of the invention are those which contain ether groups in the repeat unit, but which are free from lateral hydroxyl groups. Said polysulfones are in particular those containing a repeat unit of the formula - OA30A4SOzA4 - , wherein A3 and A4 are divalent arylene groups, especially phenylene groups, which can be substituted by chlorine or Cl-C4alkyl, for example methyl groups. Such polysulfones are obtained in a manner known per se by reacting 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 preferably, the polysulfone resins used are those containing a repeat unit of the formula - OAs - Yl - AsOA6 - SO2 - A6 -wherein As and A6 are each a phenylene group which is unsubstituted or substituted by chlorine or C1-C4alkyl groups, e.g. methyl groups, and Y
is a carbon-carbon bond, the -SOz- group or an aliphatic hydrocarbon group, especially one containing no more than four carbon atoms, e.g. a hydrocarbon group of the formula - CH2 - or ~
It is especially preferred to use thermoplastic polysulfone resins containing repeat units of formula V:
_ C~H3 _ _ _ --¢~ SO2~ -~ (V), .=. .=. .=. .=.
H3 -n wherein n preferably has an average value of 50-120.
Examples of particularly advantageous polysulfones are the compounds obtainable 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, has a deflection temperature under load (ASTM specification D648) of 175C and contains an average of 50-80 repeat units of formula V per molecule, it being possible to assume a molecular weight range of about 22,000-35,000.
Also suitable are a similar substance obtainable from the Union CarbideCorporation under the name "Polysulfone P2300", which, according to the manufacturer, has a molecular weight range of 30,000-50,000, from which it can be assumed that the substance contains an average of about 68-113 repeat units of formula v per molecule, and a similar substance obtainable from the Union Carbide Corporation under the name "Poly-sulfone P3500", which, according to the manufacturer, has a molecular weight range between that of Polysulfone Udel P1800 and that of "Polysulfone P2300", the molecular weight being ca. 35,000.
_ ~,:
According to the invention, it is also possible to use mixtures of two or more thermoplastics as component (c).
Particularly suitable as thermoplastics (c) are polyimides such as - polyimides containing phenylindane units, e.g. those disclosed in US
patent 3 856 752 and in European patent document A 92 524, especially those with a glass transition temperature of about 305C and an average molecular weight of ca. 65,000, e.g. Matrimid~ 5218 from Ciba-Geigy, - homopolyimides and copolyimides of at least one aromatic tetracar-boxylic acid and at least one aromatic diamine, e.g. those disclosed in US patent 4 629 777, and - homopolyimides and copolyimides such as those disclosed -in European patent documents A 162 017 and A 181 837 and in US patent 4 629 685.
Other preferred thermoplastics (c) are polyetherimides such as the products commercially available from General Electric under the name Ultem~ (e.g. Ultem~ 1000). Other preferred thermoplastics are polyether-sulfones such as Victrex~ PES 100 P from ICI or Udel P 1800 from Union Carbide.
Examples of suitable polyamide-imides are the compounds disclosed in US patents 3 894 114, 3 948 835, 3 926 911 and 3 950 408.
The amine- or carboxyl-terminated rubbers based on butadiene or buta-diene-acrylonitrile, which may be present as component (d) in the curable mixtures of the invention, are known and are commercially available from B.F. Goodrich under the name Hycar~, which are reactive liquid polymers.
The amine-terminated (AT) or carboxyl-terminated (CT) reactive liquid polymers are homopolymers of butadiene (B) or copolymers of butadiene and acrylonitrile (BN). In some of the products obtainable, additional reactive groups, for example vinyl or carboxyl groups, are distributed throughout the polymer chain.
For the carboxyl-terminated butadiene-acrylonitrile rubber (CTBN), for example, the structure can be represented in simplified form as follows:
~ ~37088 HOOC ~ CH2-CH=CH-CH2~ CHz-~1l) ] COOH , wherein x is a number from 1 to 10, preferably 2-7, y is a number from 1 to 5, preferably 1-3, and z is a number from 1 to 30, prefer-ably 5-15.
As component (d), the mixtures of the invention preferably contain an amine-terminated rubber based on butadiene or butadiene-acrylonitrile, especially an amine-terminated rubber based on butadiene.
The mixtures of the invention can be prepared by thoroughly mixing all the components or dissolving them in one another, it being possible for the individual components to be added in different orders. For example, the thermoplastic can be dissolved in the epoxy resin, with heating, and the other ingredients can be added after the solution has cooled. Another possible method is to prepare a solution of the thermoplastic in an inert solvent, e.g. in methylene chloride, and to mix this solution with the mixture of epoxy resin hardeners.
The mixtures of the invention have many possible uses and are suitable for example as casting resins, laminating or impregnating resins, moulding compounds, sealing compounds and potting and insulating com-pounds in electrical engineering, and preferably as adhesives and as matrix resins for composites, especially for the manufacture of prepregs for fibre-reinforced plastics.
If desired, especially when modifiers are also used, the mixtures of the invention can be dissolved in an organic solvent such as toluene, xylene, methyl ethyl ketone, methylene chloride or a similar solvent or solvent mixture conventionally used in the paint industry. Such solutions are particularly suitable as impregnating or coating compositions.
Conventional modifiers, such as extenders, fillers and reinforcing agents, pigments, dyes, organic solvents, plasticizers, levelling agents, thixotropic agents, flame retardants or mould release agents, can also be added to the curable mixtures of the invention, before curing, in any ~_ 11 - 1 337~88 phase. Examples of extenders, reinforcing agents, fillers and pigments which can be used in the curable mixtures of the invention are: liquid coumarone-indene resins, textile fibres, glass fibres, asbestos fibres, boron fibres, carbon fibres, polyethylene powder, polypropylene powder, quartz powder, mineral silicates such as mica, asbestos powder, ground shale and kaolin, powdered chalk, antimony trioxide, bentones, litho-pones, barite, titanium dioxide, carbon black, graphite, oxide pigments such as iron oxide, or metal powders such as aluminium powder or iron powder. If the mixtures of the invention are used for the manufacture of prepregs, it is particularly desirable to add short fibres.
Examples of levelling agents which can be added when the curable mixtures are used especially for surface protection are silicones, liquid acrylic resins, cellulose acetobutyrate, polyvinylbutyral, waxes, stearates etc.
(some of which are also used as mould release agents).
Examples of plasticizers which can be used to modify the curable mixtures are dibutyl, dioctyl and dinonyl phthalate, tricresyl phosphate, tri-xylenyl phosphate and diphenoxyethylformal.
The mixtures of the invention are preferably cured by being heated to atemperature in the range from 120 to 250C, especially 160 to 220C.
Curing can also be carried out in two or more stages, in known manner, the first curing stage being carried out at a low temperature and the postcure at a higher temperature.
If desired, active diluents, e.g. the diglycidyl ether of neopentyl glycol, butanediol or hexanediol, can be added to the curable mixtures in order to lower the viscosity.
The present invention further relates to the use of the mixtures of theinvention for the manufacture of cured moulded materials and to their use for the manufacture of prepregs for fibre-reinforced composites. The prepregs can be manufactured in a manner known per se, e.g. by the impregnation process in the presence of one of the above-mentioned solvents or a halogenated solvent such as methylene chloride, or by the hot melt process.
_ - 12 ~ 1 337088 The moulded materials of the invention are distinguished in general by high glass transition temperatures in combination with good mechanical strength properties, and especially by an excellent fracture toughness and a very high extensibility.
In the Examples, the following compounds are used as epoxy resin, thermoplastic or rubber:
Epoxy resin A: N,N,N',N'-Tetraglycidyl derivative of 4,4'-diaminodi-phenylmethane with an epoxy content of 7.8 equivalents/kg and a viscosity of 13,500 mPa-s at 50C.
Epoxy resin B: N,N,N',N'-Tetraglycidyl derivative of 4,4'-diaminodi-phenylmethane with an epoxy content of 9.1 equivalents/kg and a viscosity of 5000 mPa-s at 50C.
Epoxy resin C: Bisphenol A diglycidyl ether with an epoxy content of 5.2 to 5.4 equivalents/kg and a viscosity of 103-123 MPa-s at 25C.
Epoxy resin D: Bisphenol F diglycidyl ether with an epoxy content of 5.5 to 5.9 equivalents/kg and a viscosity of 3000-10,000 MPa-s at 25C.
Epoxy resin E: Phenolic novolak epoxy resin with an epoxy content of 5.6 to 5.8 equivalents/kg and a melting viscosity of 1100-1700 MPa-s at 50C.
Epoxy resin F: N,N-Diglycidyl-p-aminophenol glycidyl ether (ERLA~ 0510).
Polysulfone I: Polysulfone Udel P1800~ (Union Carbide Corporation) with a melting point in the range from 350 to 370C, a deflection temperature under load (according to ASTM D 648) of 175C, a glass transition temperature of 200C and a molecular weight range of ca. 22,000-23,000.
Polyetherimide I: Polyetherimide Ultem~ 1000 (General Electric) with a glass transition temperature of 219C and containing the repeat struc-tural unit of the formula `~ 1 337088 ~ C
~ CH3 / ~ / \ ~-\
Polyethersulfone I: Polyethersulfone Victrex~) P 5003 (ICI) with a deflec-tion temperature under load (according to IS0 75) of 215C and containing the repeat structural unit of the formula ~---SO2~
Example 1: 15 g of polysulfone I are dissolved at 150C in 128 g (1 epoxy equivalent) of epoxy resin A. 71 g (0.9 amine hydrogen equivalent) of bis(3,5-diethyl-4-aminophenyl)methane are then mixed with the solution and the mixture is cooled to about 130C. 10 g (0.07 amine hydrogen equivalent) of N,N'-dicyclohexyl-1,6-diaminohexane are mixed with this mixture. The resin mixture is viscous at room temperature and still tacky after storage for 5 weeks at room temperature. The mixture is freed from included air bubbles and poured into a 4 mm thick aluminium (Anticorodal) mould. Mouldings having the following properties are obtained after a curing time of 2 hours at 160C and 2 hours at 180C:
Glass transition temperature (Tg, measured with a Mettler "TMA 3000"
instrument as the peak maximum of the penetration speed) = 198C
Flexural strength (FS) according to IS0 178 at 23C = 131 MPa Flexural elongation (FE) according to IS0 178 = 11 %.
Example 2: A resin mixture is prepared as in Example 1, this time withthe addition of 77 g (1.0 equivalent) of bis(3,5-diethyl-4-aminophenyl)-methane and no other diamine. The mixture loses its tackiness after storage for 6 days at room temperature. The mouldings cured under identical conditions have the following properties:
- 14 - ~ 8 Tg = 203C
FS = 133 MPa FE = 13.2 %.
Example 3: 40 g of polyetherimide I are dissolved in 200 g of methylenechloride at room temperature and mixed thoroughly with 128 g (1 equiva-lent) of epoxy resin A. The solvent is evaporated off with stirring and heating to 150C. 71 g (0.9 equivalent) of bis(3,5-diethyl-4-amino-phenyl)methane and 10 g (0.07 equivalent) of N,N'-dicyclohexyl-1,6-di-aminohexane are added as in Example 1. The curable mixture has a very high viscosity at room temperature and still exhibits a good tackiness even after storage for 20 days. In the DSC diagram with a heating rate of 10/min, the curing reaction reaches the ~x; ~ exothermicity (T max) at 235C. The viscosity (~) is 7600 mPa-s at 120C. Mouldings having the following properties are obtained after a curing time of 2 hours at 160C
and 2 hours at 200C:
Tg = 208C
FS = 142 MPa FE = 10.1 %.
Example 4: Example 3 is repeated, this time with a mixture of 20 g of polysulfone I and 20 g of polyetherimide I being used instead of 40 g of polyetherimide I. The mouldings produced under identical curing condi-tions have the following properties:
T max (DSC) = 237C
= 4800 mPa-s Tg = 139 MPa FE = 9.0 %.
Example 5: Example 3 is repeated and 3 g of the amine-terminated butyl-nitrile rubber Hycar~ ATBN 1300 x 16 (Goodrich) are also added to the curable mixture. The mouldings produced under identical curing conditions have the following properties:
T max (DSC) = 234C
(120C) = 7000 mPa-s ~~ - 15 - 1 3 3 7 0 8 8 FS = 141 MPa FE = 12.9 %.
Example 6: 35 g of polyetherimide I are dissolved in 200 ml of methylene chloride. 110 g (1 equivalent) of epoxy resin B are then added and the methylene chloride is distilled off by heating, with stirring. The mixture is then heated to about 150C and 55 g (0.7 equivalent) of bis(3,5-diethyl-4-aminophenyl)methane, 24 g (0.3 equivalent) of bis(3-methyl-4-amino-5-isopropylphenyl)methane and 3 g of Hycar~ ATBN 1300 x 16 are dissolved therein. Mouldings produced from this mixture as in Example 1 have the following properties:
Tg = 197C
FS = 148 MPa FE = 11.6 %.
The uncured resin mixture has a viscosity of 2550 mPa-s at 120C and a viscosity of 52,000 mPa-s at 70C and can easily be processed, for example from a solution in methylene chloride, to give thin films (0.1 mm), as used for the manufacture of prepregs. The films exhibit a good tackiness and are still tacky and transparent even after storage for several days, i.e. the hardener has not crystallized out in the resin.
Example 7: A curable mixture consisting of 60 g (0.47 equivalent) of epoxy resin A, 40 g (0.21 equivalent) of epoxy resin C, 31.8 g (0.41 equivalent) of bis(3,5-diethyl-4-aminophenyl)methane, 15.2 g (0.24 equivalent) of bis(3-ethyl-5-methyl-4-aminophenyl)methane and 20 g of polysulfone I is prepared as in Example 1. The mixture can be pro-cessed by melting to give a film of good tackiness. After storage for several days, the film shows no signs of recrystallization. The mouldings cured under such conditions have the following properties:
Tg = 206C
FS = 130 MPa FE = 11.3 %.
~ - 16 - 1 33708~
Example 8: Another mixture is prepared from 80 g of epoxy resin A, 20 g of epoxy resin D, 5 g of a carboxyl-terminated rubber based on butadiene and acrylonitrile (= Hycar~ CTBN 1300 x 13), 43 g of bis(3,5-diethyl-4-aminophenyl)methane (hardener II), 11.5 g of bis(3-methyl-4-amino-5-iso-propylphenyl)methane (hardener I), 10 g of polysulfone I and 15 g of polyetherimide I. Before the thermoplastic and amine are added, the carboxyl-terminated rubber is prereacted for 1 hour at 150C. The film obtained shows no signs of recrystallization. The cured moulding has the following properties:
Tg = 205C
FS = 117 MPa FE = 5.1 %.
Example 9: Tacky films which also do not crystallize out are obtained with the following mixtures:
A B
Epoxy resin A 80 g (0.63 equiv.) 80 g (0.63 equiv.) Epoxy resin E 20 g (0.11 equiv.) 0 Epoxy resin F 0 20 g (0.21 equiv.) Hardener II 43 g (0.56 equiv.) 43 g (0.56 equiv.) Hardener I 11.5 g (0.15 equiv.) 0 Hardener III*) 0 14 g (0.15 equiv.) Polyethersulfone I 20 g 20 g *) Hardener III = bis(3,5-diethyl-4-amino-6-chlorophenyl)methane The mouldings cured as in Example 1 have the following properties:
A B
Tg [C] 208 213 FS [MPa] 138 145 FE [%] 8.4 10.2.
Example 10: Production of carbon fibre laminates:
a) With the mixture according to Example 3, a unidirectional prepreg is produced by melting ("T-300 6K" carbon fibre from TORAY). A unidirec-tional laminate is produced in an autoclave by the vacuum bag technique (heating by 3C/min up to 180C, followed by 3 hours at 180C and 7 bar _ - 17 - 1 3 3 7 0 8 8 pressure). The laminates exhibit an interlaminar shear strength (ILSS
according to DIN 29 971) of 94 MPa at 23C and of 56 MPa at 120C. After storage in water for 14 days at 70C, the ILSS is 83 MPa at 23C and 44 MPa at 120C.
b) A laminate produced from a mixture according to Example 6 has the following properties:
Tg = 219C
ILSS at 23C = 81 MPa ILSS at 120C = 60 MPa ILSS at 23C = 88 MPa } after storage in water ILSS at 120C = 51 MPa for 14 days at 70C
FS at 0C = 1870 MPa FS at 90C = 91 MPa Water absorption = 0.5 %.
Claims (12)
1. A curable mixture comprising (a) as epoxy resin component, 50 to 100% by weight of a tetraglycidyl compound of formula I:
(I), wherein R1, R2, R3 and R4 are each independently of the other a hydrogen atom, a halogen atom or C1-C4alkyl and X is a direct bond, methylene, isopropylidene, 0, C0, S or 502, and 0 to 50 % by weight, based on the tetraglycidyl compound of formula I, of a diepoxy compound or of a polyepoxy compound differing from the compound of formula I, (b) as hardener for the epoxy resin component, the diamine of formula II:
(II) in an amount such that there are 0.2 to 1.1 amine hydrogen equivalents per epoxy equivalent of epoxy resin component (a), a diamine of formula III:
(III), wherein R5, R6, R7 and R8 are each independently of the other C1-C4alkyl, no more than two of the substituents R5 to R8 being ethyl, and R9, R10, R11 and R12 are each independently of the other a hydrogen or halogen atom, in an amount such that there is 0.0 to 0.8 amine hydrogen equiva-lent per epoxy equivalent, and a disecondary diamine of formula IV:
( IV), wherein Y is a polymethylene radical which is unsubstituted or substi-tuted by C1-C4alkyls and contains at least 4 C atoms in the linear polymethylene chain, and R13 and R14 are each a saturated carbocyclic ring which is unsubstituted or substituted by C1-C4alkyls, or a ring system containing at least 5 ring carbon atoms, in an amount such that there is 0.0 to 0.2 amine hydrogen equivalent per epoxy equivalent, the sum of the amine hydrogen equivalents of the diamines of formulae II, III and IV being not greater than 1.2, (c) 10 to 60 % by weight, based on epoxy resin component (a), of a thermoplastic with a glass transition temperature of at least 150°C, and (d) 0 to 20 % by weight, based on epoxy resin component (a), of an amine-or carboxyl-terminated rubber based on butadiene or butadiene-acrylo-nitrile.
(I), wherein R1, R2, R3 and R4 are each independently of the other a hydrogen atom, a halogen atom or C1-C4alkyl and X is a direct bond, methylene, isopropylidene, 0, C0, S or 502, and 0 to 50 % by weight, based on the tetraglycidyl compound of formula I, of a diepoxy compound or of a polyepoxy compound differing from the compound of formula I, (b) as hardener for the epoxy resin component, the diamine of formula II:
(II) in an amount such that there are 0.2 to 1.1 amine hydrogen equivalents per epoxy equivalent of epoxy resin component (a), a diamine of formula III:
(III), wherein R5, R6, R7 and R8 are each independently of the other C1-C4alkyl, no more than two of the substituents R5 to R8 being ethyl, and R9, R10, R11 and R12 are each independently of the other a hydrogen or halogen atom, in an amount such that there is 0.0 to 0.8 amine hydrogen equiva-lent per epoxy equivalent, and a disecondary diamine of formula IV:
( IV), wherein Y is a polymethylene radical which is unsubstituted or substi-tuted by C1-C4alkyls and contains at least 4 C atoms in the linear polymethylene chain, and R13 and R14 are each a saturated carbocyclic ring which is unsubstituted or substituted by C1-C4alkyls, or a ring system containing at least 5 ring carbon atoms, in an amount such that there is 0.0 to 0.2 amine hydrogen equivalent per epoxy equivalent, the sum of the amine hydrogen equivalents of the diamines of formulae II, III and IV being not greater than 1.2, (c) 10 to 60 % by weight, based on epoxy resin component (a), of a thermoplastic with a glass transition temperature of at least 150°C, and (d) 0 to 20 % by weight, based on epoxy resin component (a), of an amine-or carboxyl-terminated rubber based on butadiene or butadiene-acrylo-nitrile.
2. A mixture according to claim 1, wherein epoxy resin component (a) consists to the extent of 100 % by weight of a compound of formula I.
3. A mixture according to claim 1, wherein epoxy resin component (a) consists of a compound of formula I in which X is methylene and R1 to R4 are each a hydrogen atom.
4. A mixture according to claim 1, wherein hardener (b) is a mixture of the diamine of formula II and a diamine of formula III or IV.
5. A mixture according to claim 1, wherein hardener (b) is a mixture of the diamine of formula II and a diamine of formula III.
6. A mixture according to any one of claims 1 and 5, wherein, in the diamine of formula III, R5, R6, R7 and R8 are each independently of the other methyl, ethyl, propyl or isopropyl, no more than two of the substituents R5 to R8 being ethyl, and R9, R10, R11 and R12 are each a hydrogen atom.
7. A mixture according to claim 6, wherein, in the diamine of formula III, R5, R6, R7 and R3 are each independently of the other methyl or isopropyl.
8. A mixture according to claim 1, wherein hardener (b) is a mixture of the diamine of formula II and a diamine of formula IV.
9. A mixture according to any one of claims 1 and 8, wherein, in the diamine of formula IV, Y is an unsubstituted polymethylene radical containing 4 to 8 C atoms and R13 and R14 are each cyclopentyl or cyclohexyl.
10. A mixture according to claim 1, wherein thermoplastic (c) is a polysulfone, polyethersulfone, polyimide or polyetherimide.
11. A mixture according to claim 10, wherein thermoplastic (c) is a polysulfone or polyetherimide.
12. A mixture according to claim 11, wherein component (d) is an amine-terminated butadiene or butadiene-acrylonitrile rubber.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH313588 | 1988-08-24 | ||
| CH3135/88-0 | 1988-08-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1337088C true CA1337088C (en) | 1995-09-19 |
Family
ID=4249374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 609004 Expired - Fee Related CA1337088C (en) | 1988-08-24 | 1989-08-22 | Curable epoxy resin mixture |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0356392A3 (en) |
| JP (1) | JPH02102218A (en) |
| BR (1) | BR8904234A (en) |
| CA (1) | CA1337088C (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2478343A (en) * | 2010-03-05 | 2011-09-07 | Hexcel Composites Ltd | Asymmetric bis-aniline resin curing agent |
| WO2019122575A1 (en) | 2017-12-22 | 2019-06-27 | Compagnie Generale Des Etablissements Michelin | Epoxy-functionalized novolak resin composition |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5008334A (en) * | 1989-02-28 | 1991-04-16 | Basf Corporation | Resins of epoxy/aromatic diol copolymer and block copolymer of epoxy/aromatic diol copolymer and a epoxy-capped polybutadiene (co)polymer |
| EP0487452A3 (en) * | 1990-11-19 | 1993-04-28 | Ciba-Geigy Ag | Curable epoxy resin composition |
| JPH0871099A (en) * | 1994-09-05 | 1996-03-19 | Mitsuyuki Kanda | Cold reserving apparatus |
| JP2001081438A (en) * | 1999-09-14 | 2001-03-27 | Sony Chem Corp | Connecting material |
| RU2486217C1 (en) * | 2011-12-21 | 2013-06-27 | Открытое акционерное общество "Национальный институт авиационных технологий" (ОАО НИАТ) | Hot-melt binder, method for production thereof, prepreg and honeycomb panel based thereon |
| JP5900258B2 (en) * | 2012-09-11 | 2016-04-06 | 株式会社デンソー | Epoxy resin production method and curable epoxy resin composition |
| CA3059595A1 (en) * | 2017-04-18 | 2018-10-25 | Huntsman Advanced Materials Americas Llc | Curable resin system |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6198727A (en) * | 1984-10-22 | 1986-05-17 | Mitsubishi Petrochem Co Ltd | Epoxy resin composition |
| JPS61250021A (en) * | 1985-04-30 | 1986-11-07 | Toray Ind Inc | Matrix resin composition for prepreg |
-
1989
- 1989-08-15 EP EP19890810606 patent/EP0356392A3/en not_active Withdrawn
- 1989-08-22 CA CA 609004 patent/CA1337088C/en not_active Expired - Fee Related
- 1989-08-23 BR BR8904234A patent/BR8904234A/en unknown
- 1989-08-24 JP JP21840889A patent/JPH02102218A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2478343A (en) * | 2010-03-05 | 2011-09-07 | Hexcel Composites Ltd | Asymmetric bis-aniline resin curing agent |
| WO2019122575A1 (en) | 2017-12-22 | 2019-06-27 | Compagnie Generale Des Etablissements Michelin | Epoxy-functionalized novolak resin composition |
| US11674035B2 (en) | 2017-12-22 | 2023-06-13 | Compagnie Generale Des Etablissements Michelin | Epoxy-functionalized novolak resin composition |
Also Published As
| Publication number | Publication date |
|---|---|
| EP0356392A3 (en) | 1991-09-18 |
| BR8904234A (en) | 1990-04-10 |
| JPH02102218A (en) | 1990-04-13 |
| EP0356392A2 (en) | 1990-02-28 |
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