GB2208231A

GB2208231A - Curable epoxy resin compositions containing a tetraglycidyl ether of a tetramethylol compound

Info

Publication number: GB2208231A
Application number: GB8817080A
Authority: GB
Inventors: Rolf Schmid; Alfred Renner; Werner Stauffer
Original assignee: Ciba Geigy AG
Current assignee: Novartis AG
Priority date: 1987-07-23
Filing date: 1988-07-18
Publication date: 1989-03-15
Also published as: GB8817080D0; NL8801857A; SE8802700D0; IT8821455A0; DE3824676A1; IT1226284B; CH672492A5; SE8802700L; ES2007540A6; FR2618442A1; BR8803679A; JPS6465117A

Description

t; 2208231- K-16597/+ Curable epoxy resin compositions containing a

tetraglycidyl ether of a tetramethylol compound The Invention relates to hot-curable compositions of matter which are stable on storage and contain tetraglycidyl ethers of certain tetramethylol compounds, epoxy resins having a functionality of 2-2.5, phenolic curing agents and accelerators and to the use thereof for the production of moulded articles, in particular of prepregs for fibre- reinforced composite materials and of adhesive films.

Many curable epoxy resin compositions which, inter alia, also contain phenolic curing agents are known. Thus, for example, Japanese preliminary published application 76/129,498 describes compositions of matter containing polyfunctional epoxy resins, phenolic curing agents and accelerators and also the use thereof for the production of prepregs for special electrical insulating materials. US 4,322,456 discloses mixtures of epoxy resins, phenolic curing agents and accelerators for which the functionality of the epoxy resins and/or of the curing agents is preferably greater than 2 and which are suitable for the production of curable coatings, especially in the form of powder coatings.

The present invention relates to hot-curable compositions of matter which are stable on storage containing 0 a) 10 to 80 parts by weight of a tetraglycidyl ether of the formula I 0 A21CH-CH2-111-C,/"' C 0 \ 0 \ ( /n \CH2--O-CH2-CIPCHz 0 CHz-0-CHz-Cl-\CHP- (1) 1 1 1 1 /01 in which X is a group -C=O, -CH-OH or -CH-O-CH2-CH 42 _Cl'2, R is hydroge'n or methyl and n is an integer from 2 to 4, b) 90-20 parts by weight of an epoxy resin having a functionality of c) a diphenol, the amount of the diphenol being chosen in such a way that 0.7-1.2 hydroxyl equivalents of the diphenol (c) are used per epoxy equivalent of the epoxy resins (a) and (b), and d) 0.05-5% by weight, based on the epoxy resins (a) and (b), of an accelerator.

The compositions according to the inventio= are suitable for the production of moulded articles, prepregs and adhesive films, and the cured products are distinguished by outstanding thermal and mechanical properties, in particular by a high heat distortion resistance and also a high impact of flexural strength.

Furthermore, the compositions have very good processing properties, for example a high homogeneity, a long pot life and a favourable tack, which is maintained even after relatively long storage at room temperature.

In addition, they are distinguished in particular by a low viscosity even at room temperature, so that they are particularly suitable for solventfree applications.

The tetraglycidyl ethers (a) of the formula I and also the use thereof as epoxy resins are known. These compounds and the preparation thereof are described in US 4,549,008.

Possible epoxy resins (b) for the present compositions are all those which have a functionality of 2-2.5 and which can be cured by means of diphenols (c) in the presence of accelerators (d).

Epoxy resins having a functionality of 2 are to be understood as meaning, for example those resins which have, on average, 2 epoxy groups per molecule.

Suitable epoxy resins (b) are, for example di- or polyglycidyl ethers.6f cycloaliphatic polyols such as 2,2-bis(4'-hydroxycyclohexyl)propane, dior polyglycidyl ethers of polyhydric phenols such as resorcinol, bis(41hydroxyphenyl)methane (bisphenol F), 2,2-bis-(41hydroxyphenyl)propane 1 11 il (bisphenol A), 2,2-bis-(41-hydroxy-31,51-dibromophenyl)propane, or condensation products of phenols with formaldehyde such as phenol novolaks and cresol novolaks; furthermore, di- or poly($-methylglycidyl) ethers of the abovementioned polyalcohols and polyphenols; Polyglycidyl esters and poly(B-methylglycidyl) esters of polybasic carboxylic acids such as phthalic acid, terephthalic acid, tetrahydrophthalic acid and hexahydrophthalic acid; N-Glycidyl derivatives of amines, amides and heterocyclic nitrogen bases such as N,N-diglycidylaniline, N,N-diglycidyltoluidine, N,N-diglycidylN, NI-ethyleneurea, N,NI-diglycidyll-5,5-dinethylhydantoin, N,NI-diglycidyl5-isopropylhydantoin, N,N'-diglycidyl-5,5-dimethyl-6-isopropyl5,6dihydrouracil; Multifunctional epoxy resins such as the 2,6-disubstituted 4- epoxypropylpheny1glycidyl ethers and adducts thereof described in EP 205, 409 and EP 204,659; Bisphenols which are substituted by two glycidyloxy and 2,3-epoxypropyl groups each, for example 2,2-bis(31-epoxypropyl-41- epoxypropylphenyl)propane described in GB 828,364; Glycidyloxy-substituted benzophenones and glycidyloxy diketones such as the compounds described in US 4,649,181.

In general, mixtures of two or more epoxy resins can also be used as component (a) and/or as component (b) in the materials according to the invention.

Particularly suitable tetraglycidyl ethers (a) of the compositions accor ding to the invention are compounds of the formula I, in which the symbol I I X is the group -CH-011 or -C=0. Further preferred compounds are those-i'n which R is hydrogen and n is the number 2 or 3. A very particularly pre ferred component (a) is the tetraglycidyl ether of 2,2,6,6-tetramethylol cyclohey3nol.

Preferred expoxy resins (b) of the compositions according to the invention are compounds which have an epoxide content of 5-11 equivalents/kg and are glycidyl ethers, glycidyl esters or N-glycidyl derivatives of cycloaliphatic, aromatic or heterocyclic compounds.

Particularly preferred components (b) are epoxy novolaks or glycidyl derivatives of a bisphenol or a hydantoin, in particular those which have a functionality of 2-2.2 and are an epoxy phenol novolak or a glycidyl derivative of bisphenol A, bisphenol F or 4,41-dihydroxybiphenyl.

Suitable diphenols (c) are, for example, mononuclear and polynuclear dihydroxyaromatics containing fused 'or nonfused benzene rings. Particularly suitable compounds are those of the formula II or III OH -T-0 (11) 6 /-R (III), HO/X 6=0 =X\OH. 's H Is H in which T is the direct bond, methylene, isopropylidene, 0, S, CO or S02 and R is hydrogen or Cl-COlkyl, dihydroxynaphthalene or mixtures of these compounds. Of the compounds of the formula I, preference is given to those in which the hydroxyl groups are bound in the 4,4'-position.

Particularly preferred diphenols (c) are bisphenol A, bisphenol F, 4, 41dihydroxydiphenyl sulfide, 2,6-dihydroxynaphthalene and in particular 2, 7-dihydroxynaphthalene, 4,41-dihydroxydiphenyl ether or 2,6dihydroxytoluene, A particularly suitable phenolic curing agent is a mixture of 2,6- dihydroxytoluene and 2,7-dihydroxynaphthalene. Particularly good results are obtained by mixing equal amounts by weight of these compounds in the melt at about 1800C, grinding the product obtained after solidification of the melt to a fine powder and then using this powder as the curing agent.

-1 1, 7 1 If desired, the compositions of matter according to the invention can contain as curing agents also a certain amount of one or more tri- or polyphenols such as, for example 2,4,6-tris[21-(p-hydroxyphenyl)- 21propyl]benzene ("tris-TW from Mitsui Petrochemical) in addition to the diphenols (c). However, in general not more than 30% of the phenolic hydroxyl groups should come from a tri- or polyphenol and the remainder of the hydroxyl groups should belong to a diphenol. In general, phenol or cresol novolaks are not suitable as phenolic curing agents of the compositions according to the invention. It goes without saying that in the case where not only diphenols but also tri- or polyphenols are used, the total amount of phenolic curing agent (c) is chosen in such a way that overall 0.7-1.2 hydroxyl equivalents of the phenols used per epoxy equivalent of the epoxy resins used are contained in the composition according to the invention.

Suitable accelerators (d) of the curable compositions of matter are all compounds which are known to a person skilled in the art for the acceleration of the crosslinking reaction of epoxy resins by means of phenolic curing agents, for example tertiary amines, salts thereof or quaternary ammonium compounds such as tetramethylammonium chloride, phosphonium salts, alkali metal alcoholates, for example sodium hexanetriolate, Lewis acids, for example BF3 or SnC14, and nitrogencontaining heterocycles such as pyridines, imidazoles and derivatives thereof. Particularly suitable accelerators (d) are imidazoles and Nacylimidazoles (imidazolides).

Examples of suitable imidazoles are compounds of the formula IV R3 XR2 HN \ > (IV) 0 A1 in which Rl, R2 and R3 -C12 independently of one another are hydrogen, Cl alkyl, CS-Clocycloalkyl or C6-Cloaryl. Preference is given in particular to 2-methyl-, 2-ethyl-, 2-phenyl- and 2-ethyl-4-methyl-imidazole.

Suitable N-acylimidazoles (imidazolides) are, for example the compounds described in US 4.436,892, US 4,587,311 and Japanese published application 74/7,599. Particularly suitable compounds are those of the formula V 8# R 3\ "R2 R /R R6--- R7 / \ R8 \.> 11 (V) 1 in which Rl to R3 are as defined above and R4 to R8 independently of one another are hydrogen, C l-Cl2alkyl,halogen, nitro or trifluoromethyl. Examples of suitable imidazolides are 1-(21,41,61-trimethylbenzoyl)- 2ethylimidazole, 1-(21,61-dichlorobenzoyl)-2-methylimidazole, 1-(2',41, 61trimethylbenzoyl)-2-methylimidazole and 1-(214161-trimethylbenzoyl)2phenylimidazole.

In addition to components (a) to (d) the curable compositions of matter according to the invention can, if advantageous, also contain (e) 10-140, preferably 20-130, in particular 80-120 parts by weight, based on 100 parts by weight of components (a) to (c), of a thermoplastic having a glass transition temperature of at least 1800C. The cured products produced using the thermoplastic-containing compositions are distinguished by outstanding thermal and mechanical properties, in particular by a high heat distortion resistance, a high fracture toughness, flexural and impact flexural strength and also a very high extensibility.

Thermoplastics (e) which can be used in the curable compositions of matter according to the invention are all the known polymers which have a sufficiently high glass transition temperature, that is, I 1800C, and are miscible with the epoxy resin/curing agent system according to the application.

Based on their properties, the thermoplastics employed are preferably polyamide imides, polysulfones or polyether sulfones and particularly preferably polyimides and polyether imides, especially those having a p 1 r glass transition temperature of 180 - 3500C. Particularly preferred thermoplastics are those having a glass transition temperature of 190 2500C. In the case where polyether imides are used, preference is given in particular to polymers having a T 9 of 220 to 2500C and, where polyimides are used, preference is given to those having a T 9 from 280 to 3400C.

In the case where a polysulfone is used as thermoplastic, suitable compounds are those described in EF-A 194,232 as polysulfone component (c). These compounds are, for example, obtainable (from Union Carbide Corporation) under the name "polysulfone Udel P180W, "polysulfone 2300" or "polysulfone 35OW.

According to the invention, mixtures of two or more thermoplastics can also be used as component (e).

Particularly suitable thermoplastics (e) are polyimides such as Polyimides having phenylindane units such as have been described, for example in US 3,856,752 and EP-A 92,524, in particular those having a T 9 of about 3050C and an average molecular weight of about 65,000 such as, for example Matrimidw 5218 from Ciba-Geigy, homopolyimides and copolyimides consisting of at least one aromatic tetracarboxylic acid and at least one aromatic diamine such as have been disclosed, for example, in US 4,629,777 and homopolyimides and copolyimides such as have been described, for example in EP-A 162,017, EP-A 181,837 and US 4,629,685.

Further preferred thermoplastics (e) are polyether imides, for example the products from General Electric which are available under the name D(for example Ult 1000). Further preferred thermoplastics are UltemAD polyether sulfones, for example Victrex PES 100 P from ICI or Udel P 1800 from Union Carbide.

Suitable polyamide imides are, for example the compounds described in. US 3,894,114, US 3,948,835, US 3,926,911 and US 3,950,408.

Components (a) to (e) used in the compositions according to the invention are all known compounds and can be prepared by known methods.

Particularly preferred curable compositions according to the invention are those which contain 30 to 60 parts by weight of the tetraglycidyl ether (a), 70 to 40 parts by weight of the epoxy resin (b), an amount of the diphenol (c) such that 0.8-1.1, preferably 03-1.0, hydroxyl equivalents of the diphenol are used per epoxide equivalent of the resins (a) and (b), and 0.1-1% by weight of the accelerator (d), based on the amount of (a) and (b).

The compositions accordin g to the invention can be made available by thorough mixing or dissolution of all components in one another, it being possible for the individual components to be added in different sequences. If the compositions also contain a thermoplastic, this can, for example, be dissolved in the epoxy resin and in the phenolic curing agent with heating and after cooling the accelerator and, if desired, more additives can be added. However, a solution of the thermoplastic in an inert solvent, for example methylene chloride, can be prepared and then mixed with the epoxy resin/curing agent composition.

The compositions according to the invention can be used for many purposes and are suitable, for example as casting resins, laminating or impregnating resins, moulding compositions, sealants, embedding and insulating compositions for electrical engineering and preferably as adhesives and as matrix resins for composite materials, in particular for the production of fibre-reinforced plastics.

If desired, in particular in the case where modifying agents are also used, the compositions according to 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 which is customary in the coatings industry. Such solutions are suitable in particular as impregnating agents or coating agents.

Before curing, the curable mixtures according to the invention can also 1 t be admixed at any time with customary modifying agents such as extenders, fillers, reinforcements, pigments, dyes, organic solvents, softeners, flow-improving agents, thixotropic agents, flame retardents or mould release agents. Extenders, reinforcements, fillers and pigments which can be used in the curable mixtures according to the invention are for example: liquid cumaronelindene resins, textile fibres, glass fibres, asbestos fibres, boron fibres, carbon fibres, polyethylene powder, polypropylene powder, quartz powder, mineral silicates such as mica, asbestos powder, slate powder, kaolin, chalk powder, antimony trioxide, bentone, lithopone, heavy spar, titanium dioxide, soot, graphite, oxide colours such as Iron oxide or metal powders such as aluminium powder or iron powder. In the case where the mixtures according to the invention are used for the production of prepregs, the addition of short fibres is particularly desirable.

For the practical use of the curable mixtures, especially in surface protection, it is possible to add as flow-improving agents, for example silicones, liquid acrylic resins, cellulose acetobutyrate, polyvinylbutyral, waxes, stearates and the like (which in some cases are also used as mould release agents).

Plasticizers which can be used for modifying the curable mixtures are, for example, dibutyl, dioctyl and dinonyl phthalate, tricresyl phosphate, trixylenyl phosphate and diphenoxyethyl formal.

The mixtures according to the invention are preferably cured by heating them to a temperature within the range from 120 to 2500C, in particular 160 to 2200C. The curing can be carried out in a known manner also in two or more stages, the first curing stage being carried out at lower temperature and the post-curing at higher temperatures.

If desired, active diluents, for example neopentyl glycol ether, butanediol diglycidyl ether or hexanediol diglycidyl ether can be added to the curable mixtures to reduce their viscosity.

The present invention also relates to the use of the compositioi s according to the invention for the production of cured moulded materials and also to the use for the production of prepregs for fibre-reinforced composite materials or for the preparation of adhesive films. The prepegs and the adhesive films can be prepared in a manner known per se, for example by the impregnation process in the presence of one of the abovementioned solvents. of a halogenated solvent, for example methylene chloride, or by the so-called "hot-melt" process.

The moulding materials are in general distinguished by high glass transition temperatures in combination with high mechanical strength.

The Examples which follow illustrate the invention in more detail.

Components (a)-(e) used in the Examples which follow are the following:

Tetraglycidyl ether 1: Tetraglycidyl ether of 2,2,6,6tetramethylolcyclohexanol (prepared according to Example 2 of US 4,549, 008) having an epoxide equivalent weight of 129.

Epoxy resin bl: An epoxy phenol novolak liquid at room temperature of a functionality of 2.2 having an epoxide content of 5.7 equivalents/kg and a viscosity at 500C of 1.4 Pa.s.

Epoxy resin b2: A bisphenol F diglycidyl ether having an epoxide content of 6.1 equivalents/kg and a viscosity at 250C of 6.0 Pa.s.

Polyimide 1: A polyimide containing phenylindane units having a glass transition temperature of 3050C and an average molecular weight of about 65,000 (Matrimi&EY5218, Ciba-Geigy).

Polyether imide l: A polyether Imide having repeating units of the formula 1, - 1 1 - \ A.

-N) 0 3 -,\ 0 / - \\ 0 / \ // 0 \.

0 1.1.1 N-, 1 CH3 - n and a glass transition temperature of 2190C (UlteugD 1000 from General Electric).

Example 1: a) 35 g of tetraglycidyl ether 1 and 65 g of epoxy resin U are mixed at 1200C with 20.5 g of 2,6-dihydroxytoluene and 20.5 g of 2, 7dihydroxy naphthalene. After cooling the mixture to 1000C, 0.1 g of 2phenylimidazole is added. The mixture is cooled to room temperature and a solution of 84.5 g of polyimide 1 in 82 g of methylene chloride is then added to the mixture which is thoroughly stirred until a homogeneous mixture is obtained. The mixture is used to cast a film, 0.1 mm in thickness, on silicone-treated paper by means of a doctor blade, and the solvent is evaporated at room temperature. Several film cuts, 30 x 30 mm, are placed on top of each other, compressed to a 1 mm thick moulding in a press at 1800C and cured at 1800C for 1 hour. The moulding has a T 9 (measured by means of thermomechanical analysis) of 1940C and a slight presoftening at 1040C.

b) Example la) is repeated except that 60.4 g of polyimide 1 are used to give a film moulding having a Tg of 210 and 1050C. One portion of the film is used to bond together 2 A1 sheets at 1800C and the product is postcured at 2000C for 1 hour. The cured resin has a fracture toughness (GIC) of 794 J1a2, measured by the double-torsion experiment according to "Journal of Materials Science, 10, 1334 (1975) and 14, 776 (1979)". In this procedure two aluminium sheets Extrudal 050 (AlMgSi 0.5), dimensions 200 x 20 x 5 mm, which have been treated with chromic sulfuric acid, are bonded using the curable mixture, and the bonded product is cured by applying a little pressure. This method measures the crack propagation in the bonded product, that is, the fracture energy in j/m2 is calculated from the maximum load for the crack propagation.

Example 2: Example la is repeated except that -59.2 g of 4,4dihydroxydiphenyl ether are used as the curing agent instead of 2,6dihydroxytoluene/2,7-dihydroxynaphthalene mixture used in that Ezample. The cured composition has a T 9 of 1921C and slight presoftening at 800C.

Example 3: a) 35 g of tetraglycidyl ether 1, 65 g of epoxy resin b2, 22 g of 2,6dihydroxytoluene, 22 g of 2,7-dihydroxynaphthalene, 0.1 g of 1-(V, 4',6'trimethylbenzoyl)-2-phenylimidazole and 96 g of polyimide 1 are processed according to Example la. After curing for 1 hour at 1800C and for 1 hour at 2000C, the material has a measured T 9 of 2120C.

b) The experiment is repeated using 71 g of polyimide 1 to give a material having a measured T 9 of 2220C (slight presoftening at 100OC) and a fracture toughness GIC (double-torsion experiment) of 976 j/M2.

Example 4: 33.3 g of tetraglycidyl ether 1, 33.3 g of epoxy resin bl, 33. 3 g of epoxy resin b2, 45.9 g of 2,7-dihydroxynaphthalene and 0.1 g of 2phenyllmidazole are processed according to Example 1. The cured mouldings have the following properties:

Ta (THA) Flexural strength (ISO 178) Flexural elongation (ISO 178) Impact flexural strength (ISO R 179) = 1220C = 152 MPa = 6.9 % - 38 kJ1m2 Example 5: a) 50 g of tetraglycidyl ether 1, 50 g of epoxy resin W, 38 g of 2,6dihydroxytoluene and 0.1 g of 2-phenyllmidazole are processed according to Example 1. The cured mouldings have the following properties:

Tg (7MA) Flexural strength (ISO 178) Flexural elongation (ISO 178) 1 = 1030C = 135 MPa = > 14 % Impact flexural strength (ISO R 179) = 86 M/M2 b) The experiment is repeated using 68 g of bisphenol A as phenolic curing agent to give cured mouldings on which the following properties are determined:

T 9 (TMA) Flexural strength (ISO 178) Flexural elongation (ISO 178) Impact flexural strength (ISO R 179) = 1090C = 121 MPa = 13 % = 93 kJ1m2 c) The experiment is repeated usirig 21 g of 2,6-dihydroxytoluene and 21 g of 2,7-dihydroxynaphthalene as phenolic curing agent to give cured mouldings having the following properties:

Tg (TKA) Flexural strength (ISO 178) KiiukaI elongation (ISO 178) Impact flexural strength (ISO R 179) = 1130C = 140 MPa = 12. 1 % = 68 kJ/m2 d) The experiment is repeated using 17.5 9 of 2,6-dihydroxytoluene and 17. 5 g of 2,7-dihydroxynaphthalene as phenolic curing agent to give cured mouldings having the following properties:

T 9 (TMA) Flexural strength (ISO 178) Flexural elongation (ISO 178) Impact flexural strength (ISO R 179) = 960C = 14 0 MPa > 14 % 67 kJ/M2 Example 6: a) 35 g of tetraglycidyl ether 1, 65 g of epoxy resin W, 20.5 g of 2,6dihydroxytoluene and 20.5 g of 2,7-dihydroxynaphthalene are processed as described in Example 1 to give cured mouldings having the following properties:

T 9 (THA) = 1060C Flexural strength (ISO 178) Flexural elongation (ISO 178) Impact flexural strength (ISO R 179) Fracture toughness (double-torsion experiment) 151 MPa > 13 % 9 1 kJ/m2 454 J/J b) The experiment is repeated using 59 g of 4,4'-dihydroxydiphenyl ether as phenolic curing agent to give cured mouldings having the following properties:

T 9 (TMA) Flexural strength (ISO 17B) Flexural elongation (ISO 178) impact flexural strength (ISO R 179) = 930C 113 MPa = > 14 % = 103 kJ/M2 Example 7: 40 g of tetraglycidyl ether 1 and 60 g of epoxy resin bl are heated to 1400C and the diphenol is dissolved in this mixture with stirring. After cooling to 800C 0.1 & of 2-ethyl-4-methylimidazole are added and thoroughly mixed. The mixture is poured into a mould made from Extrudal 050, dimensions 80 x 60 x 4 mm, and cured for 2 hours at 1400C and for 2 hours at 1800C. The following results are obtained Phenol Amount (g) T 9 (IRA) (00 Flexural strength (b]Pa) Flexural elongation M Impact fle-ri, al strength ki/m2 DRPE Bi s P-M 111 DHPE Bis-P-M Bis-P-P 58.5 100 100 123 123 12.6 74 HO- k.-.(Y-0P4.-OH 103 117 10 52 HO- Z.

Bis P-P H H0- \.-OH 9=0 0=0 Products of Mitsui Petrochemical Examples 8 and 9: Preparation of laminates i Example 8: 146.3 g of polyimide 1 are dissolved in 300 g of methylene chloride and then 40 9 of tetraglycidyl ether and 60 g of epoxy resin bl are added. To the homogeneous solution is slowly added dropwise a solution of 46.3 g of 2,7-dihydroxydnaphthalene and, 0.1 g of 2-ethyl- 4methylimidazole in 50 g of methyl ethyl ketone. This solution is used to impregnate a quasi unidirectional carbon fibre fabric (G 827, Brochier SA) with 3% by weight of glass fibres in the weft direction followed by drying at 500C for 16 hours. After treatment at 900C in a vacuum for 30 minutes, the prepregs (11 layers) are placed on top of each other and compressed at 2000C for 2 hours at 8 bar to give a laminate. The following results are obtained:

T 9 (TMA) Fibre content Interlaminar shear strength (ASTM 2344) = 2260C = 80.6% by weight = 60 MPa Example 9: Using the same solution as in Example 8, a unidirectional prepreg is prepared (resin content 37% by weight) from the carbon fibre T300 (Toray) by winding on a drum winder. After treatment at 900C and 50 mbar in a vacuum for 30 minutes, the prepregs (10 layers) are placed on top of each other and compressed for 1 hour at 2000 and 10 bar to give a unidirectional laminate. The laminate is postcured for 1 hour at 2000 and for 1 hour at 2100C. The following values are measured:

Tg (THA) = 2250C Flexural strength (parallel to the fibre) (ISO 178) = 1350 MPa Flexural strength (transverse to the fibre) (ISO 178) = 85 MPa Flexural elongation (parallel to the fibre) (ISO 178) = 1.3 % Flexural elongation (transverse to the fibre) (ISO 178) = 1.3 % t, Example 10: 149 g of polyether imide 1 are dissolved in 250 g of methylene chloride and then 50 g of tetraglycidyl ether 1 and 50 g of epoxy resin U are added and the mixture is thoroughly mixed. After evaporation of the solvent down to about 10%, 49 g of 2,7- dihydroxynaphthalene and 0.1 g of 2-ethyl-4-methylimidazol dissolved in methyl ethyl ketone (50%) are added dropwise with vigorous stirring. This mixture is used to prepare a film on silicone paper which is dried for 12 hours at 500C (without vacuum) and 30 minutes at 900C in a vacuum. The film is then cut and compressed on a laboratory press at a compressing temperature of 2000C for 2 minutes to give a pure resin platelet. After complete curing in an oven at 2000C for 2 hours, the moulding has a T. (TMA) of 1600C.

^1

Claims

What is claimed is:

1 1. A hot-curable composition of matter which is stable on storage containing a) 10 to 80 parts by weight of a tetraglycidyl ether of the formula I 0 C2CH-CH2-0-Cj c c 0 \\CHz--0-CH,,-C 0 C2CH-CH2-0-C1/i2:CH,, /n 0 0 CH,--0--CH,,--CH 2 (I) in which X is a group -C=O, -CH:-OH or -CE-O-CH2-CH-CH2, R is hydrogen or methyl and n is an integer from 2 to 4, 1 b) 90-20 parts by weight of an epoxy resin having a functionality of 2-2.5, c) a diphenol, the amount of the diphenol being chosen in such a way that 0.7-1.2 hydroxyl equivalents of the diphenol (c) are used per epoxy equivalent of the epoxy resins (a) and (b), and d) 0.05-5% by weight, based on the epoxy resins (a) and (b), of an accelerator.

2. A composition according to claim 1 in which the symbol X in the 1 # formula 1 is the group---CH-011 or -C=O.

3. A composition according to claim 1 in which R in the formula I is hydrogen and n Is the number 2 or 3.

4. A composition according to claim 1 in which the epoxy resin (a) is the tetraglycidyl ether of 2,2,6,6-tetramethylolcyclohexanol-

5. A composition according to claim 1 in which the epoxy resin (b) has an epoxide content of 5-11 equivalents/kg and is a glycidyl ether, glycidyl ester or an N-glycidyl derivative of a cycloaliphatic, an aromatic or a.

heterocyclic compound.

6. A composition according to claim 1 in which the epoxy resin (b) is an 1 epoxy novolak or a glycidyl derivative of a bisphenol or of a hydantoin.

7. A composition according to claim 1 in which epoxy resin (b) has a functionality of 2 - 2.2 and is an epoxy phenol novolak or a glycidyl derivative of bisphenol A, bisphenol F or 4,41-dihydroxybiphenyl.

8. A composition according to claim 1 in which diphenol (c) is a compound of the formula II or III //-X,- OH -T- ---R(III), H0/Xc=c/ -=->'\6H IHI in which T is the direct bond, methylene, isopropylidene, 0, S, CO or S02 and R is hydrogen or l-C4alkyl, a dihydroxynaphthalene or a mixture of these compounds.

9. A composition according to claim 1 in which diphenol (c) is bisphenol A, bisphenol F, 4,41-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl suifide, 2,6-dihydroxytoluene,or 2,6-dihydroxynaphthalene or 2, 7dihydroxynaphthalene.

10. A composition according to claim 9 in which diphenol (c) is a mixture of 2,6-dihydroxytoluene and 2,7-dihydroxynaphthalene.

A composition according to claim 1 in which the accelerator is an imidazole or an N-acylimidazole.

12. A composition according to claim 1 which in addition to components (a) to (d) also contains (e) 10-140 parts by weight, based on 100 parts by weight of components (a) to (c), of a thermoplastic having a glass transition temperature of at least 1800C.

13. A composition according to claim 12 in which thermoplastic (e) is a polyimide, a polyether iinide, a polyamide imide, a polysulfone or a polyether sulfone and has a glass transition temperature of 180 - 3SO?C.

14. A composition according to claim 1 containing 30 to 60 parts by weight of the tetraglycidyl ether (a), 70 to 40 parts by weight of the A epoxy resin(b), an amount of the diphenol (c) such that 0.8-1.1 hydroxyl equivalents of the diphenol are used per epoxide equivalent of the resins (a) and (b), and 0.1-1% by weight of the accelerator (d), based on the amount of (a) and (b).

15. Use of a composition according to claim 1 for the production of cured mouldings.

16.- Use of a composition according to claim I for the production of prepregs for fibre-reinforced composite materials or for the preparation of adhesive films.

Published 198B W. The Patent Office. State Hcusc. 6671 Hgl_ Ho'born. London WICIR 4TF Further copie-s may be obtai-ne-4 frcr.-. The Patent Office Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray. Kent Con. 1'87-