FR2618443A1 - CURABLE MIXTURES BASED ON EPOXY RESINS, APPLICATION OF THESE MIXTURES, AND HARDENERS CONTAINING A DIPHENOL - Google Patents

Abstract

The invention relates to curable mixtures based on epoxy resins. They contain: a) 10 to 80 parts (by weight) of an epoxy resin having a functionality of at least 3, b) 90 to 20 parts of an epoxy resin having a functionality of 2 to 2.5, c) a diphenol consisting of 0 to 80% of a compound of formula I or II: (CF DRAWING IN BOPI) (T denotes a direct bond, a methylene, an isopropylidene, O, S, CO or SO2 and R l ' hydrogen or alkyl), and from 100 to 20% of a dihydroxy-naphthalene, and d) from 0.05 to 5%, based on resins a and b, of an accelerator. These mixtures, which are not very viscous and keep well, are suitable for the manufacture of prepregs and adhesive films.

Description

26 18443

  The invention relates to thermally

  hardenable, storage stable, which contain cer-

  certain di- or polyfunctional epoxy resins,

  diphenols and / or dihydroxy-naphthalenes as

  cores, and accelerators. It also relates to the application of these mixtures to the manufacture of molded articles, more particularly of prepregs for materials

  fiber-reinforced composites and adhesive films

  sive. Many hardenable mixtures based on epoxy resins are known which also contain, inter alia, phenolic hardeners. Thus JP A 76/129 498 discloses mixtures containing polyfunctional epoxy resins, phenolic hardeners.

  accelerators and the application of these

  for the manufacture of prepregs for use in the manufacture of special electrical insulators. US Pat. No. 4,322,456 describes mixtures of epoxy resins, phenolic hardeners and accelerators in which

  the functionality of epoxy resins and / or

  cisseurs is preferably greater than 2; these mixtures are suitable for the preparation of coating products

  curable, in particular in the form of

powders or powder varnishes.

  US Pat. No. 4,288,565 discloses mixtures consisting of epoxy resins, some of which have a high epoxy equivalent weight and the others a low equivalent weight of epoxy, and phenolic hardeners which are, for at least 30%, containing at

  minus 3 hydroxy radicals per molecule.

  U.S. Patent 4,216,304 discloses blends

  liquid curable epoxy resins which contain

  a diglycidyl ether of a phenolic novolac, devoid of ester radicals and liquid at room temperature, of 2,6-dihydroxytoluene as a hardener, and

a hardening accelerator.

  DE A 2 807 666 discloses mixtures of

  polymers that contain a terminal carboxy polymer, an epoxy resin, a plasticizer, a dihydroxy compound as a hardener for the resin

  epoxy, and 2-ethyl-4-methylimidazole as an

  Hardening furnace. As dihydroxy compounds

  In addition, bisphenols and a dihydroxy naphthalene are mentioned among others. The polymer with terminal carboxyl radicals is preferably an elastomer,

  and the polymer blends are used for the manufacture of

  cation of elastic bladders for game balls.

  U.S. Patent 3,661,828 discloses materials

  molding composition containing a copolymer of glyceryl methacrylate

  dyle, acrylonitrile or methacrylonitrile and methyl methacrylate with an average

  between 1,500 and 16,000, and, as

  cement, a diphenol. These molding materials can also

  contain low molecular weight diepoxides

  reactive diluents. Among the hardening diphenols suitable

  mentioned are also bis-phenols

and 2,7-dihydroxy naphthalene.

  The subject of the present invention is

  hardenable, storage stable mixtures which contain

  (a) from 10 to 80 parts by weight of an epoxy resin having a functionality of at least 3, b) from 90 to 20 parts by weight of an epoxy resin having a functionality of 2 to 2.5; ) a diphenol whose quantity is chosen in such a way

  that, by epoxy equivalent, epoxy resins

  (a) and (b) from 0.7 to 1.2 equivalents of hydroxy of diphenol (c), this diphenol consisting of: cl) from 0 to 80% by weight of a compound corresponding to one of Formulas I and II: wherein T is the direct link, methylene, isopropylidene, O, S, CO, or SO2 and R3 represents hydrogen or a C1-C4 alkyl and 1 4 c2) from 100 to 20% by weight of a dihydroxy-naphthalene, as well as

  d) from 0.05 to 5% by weight, based on the epoxy resins

  diques (a) and (b), an accelerator.

  The mixtures according to the invention

  come for the manufacture of molded objects, pre-im-

  adhesives and adhesive films, and the cured products are distinguished by excellent thermal and mechanical properties, more particularly by high dimensional stability under heat and remarkable strength.

bending.

  In addition the mixtures have excellent properties for the implementation, for example a high homogeneity, a long "pot life" (time available for implementation after opening the container, in English "pot-life") and a favorable tack which

  even after long storage at room temperature

ambient temperature.

2618 4 4 3

  They are particularly noteworthy.

  because of their viscosity which is low from the temperature

  ambient temperature so that they are particularly suitable

  good for solvent-free applications.

  As epoxy resins (a) and (b), it is possible to envisage, for the present mixtures, all those which have a functionality of at least 3 for the first and 2 to 2.5 for the second and which can be hardened.

  by means of diphenols (c) in the presence of accelerators (d).

  By "epoxy resins having a function

  tionality equal to 3 "is meant for example the resins which

  contain on average 3 epoxy radicals per molecule.

  Epoxy resins (a) and (b) which

  The following are in particular: diglycidyl or polyglycidyl ethers of

  cycloaliphatic polyols such as bis- (4-hydroxycyclo)

  hexyl) -2,2 propane, diglycidyl ethers or polygly-

  polyphenols such as resorcinol, bisphenol

  (4-hydroxyphenyl) -methane (or bis-phenol F), the bis- (hydro-

  xy-4 phenyl) -2,2 propane (or bis -phenol A), the bis- (hydro-

  xy-4-dibromo-3,5-phenyl) -2,2 propane, tetrakis (hydroxyethyl)

  4 phenyl) -1,1,2 ethane or condensation products of phenols with formaldehyde, such as phenol novolacs and cresol novolacs and also di- or poly- (P-methyl-glycidyl) ethers polyols and polyphenols which have just been mentioned;

  polyglycidyl esters and poly (P-methyl-glycidyl)

  of polycarboxylic acids such as phthalic acid

  terephthalic acid, tetrahydrophthalic acid or hexahydrophthalic acid; diglycidyl derivatives of amino phenols, such as triglycidyl-p-amino-phenol; N-glycidyl derivatives of amines, amides or

  heterocyclic nitrogen bases, such as N, N-diglycidyl-

  aniline, N, N-diglycidyl-toluidine, N, N, N ', N'-tetragly-

  cidyl-bis (4-aminophenyl) -methane, triglycidyl isocyanurate, N, N'-diglycidyl-N, N'-ethylene-urea,

  N, N'-diglycidyl dimethyl-5,5 hydantoin, N, N'-diglycine

  5-isopropyl hydantoin or N, N'-diglycidyl dimethyl-5,5-isopropyl-5,6-dihydro-uracil; multifunctional epoxy resins such as glycidyloxy-1-glycidyl-4-benzenes disubstituted in 2,6 and their addition products which are described in European Patents 205,409 and 204,659; bis-phenols carrying 2 glycidyloxy radicals and 2 glycidyl radicals, for example 3- (3-glycidyl-4-glycidyloxyphenyl) -2,2-propane;

  glycidyl derivatives of cyclohexanols, cyclohexanols

  xanones, cyclopentanols or tetramethylolated cyclopentanones, such as the compounds which are described in US Pat. No. 4,549,008 and benzophenones carrying glycidyloxy radicals, and glycidyloxydicetones, such as the compounds

  which are described in US Patent 4,649,181.

  In general, mixtures of 2 or more than 2 epoxy resins as component (a) and / or

as component (b).

  It is highly appreciated, as epoxy resins,

  diques (a) and (b), compounds which have a

  epoxy of 5 to 11 equivalents / kg and which are glycol ethers

  cidyl esters, glycidyl esters or N-gly-

  Cidylics of cycloaliphatic, aromatic or heterocyclic compounds, especially epoxy novolacs and derivatives

  glycidyls of bis-phenols, hydantoins or tetramines

thylol-cyclohexanes.

  As epoxide resins (a), glycidyl derivatives of hydantoins and, especially, epoxidized phenolic novolaks and glycidyl derivatives of tetramethylolcyclohexanes are particularly recommended. They will have

  preferably a functionality of 3 to 4.

  Epoxy resins (b) are particularly suitable for epoxidized phenolic novolacs

  and the glycidyl derivatives of bis-phenol A and bis-phenol

  nol F. They will preferably have a functionality of 2 to 2.2.

  The mixtures according to the invention in which the hydroxy groups of the compound of formula I occupy positions 4 and 4 'and the symbol T are highly preferred.

  represents O, S, methylene or isopropylidene.

  Mixtures according to the invention in which the compound of formula

  It is a dihydroxytoluene, more particularly the di-

2,6-hydroxy toluene.

  The component (c2) of the mixtures according to the invention is a dihydroxynaphthalene, for example

  dihydroxy-1,5, -1,7, -2,6 or -2,7 naphthalene, preferably

  2,6-dihydroxy naphthalene or, better still, the

2,7-dihydroxy naphthalene.

  We greatly appreciate the mixtures in the-

  which diphenol (c) consists of the component (cl) for 20 to 60% by weight and the component (c2) for 80 to 40% by weight, and especially those in which the diphenol

  (c) consists of 50% by weight of each of the

  sante (cl) and (c2). Particularly preferred are mixtures in which diphenol (c) consists of

  2,6-dihydroxytoluene and 2,7-dihydroxy naphthalene.

  Very good results are obtained when the molar masses of these compounds are mixed in the molten state at a temperature of about 180 ° C., and the product obtained is melted after solidification of the melt in order to reduce it to a fine powder, then we use this

powder as hardener.

  The present invention also relates to a hardener for epoxy resins, hardenedBseur which contains

  a compound of formula I or II and a dihydroxy-naphthalene.

  In addition to diphenols (c) mixtures

  according to the invention may also contain as dura-

  if it brings benefits, a certain amount of

  one or more triphenols or polyphenols, such as trisZ (4-hydroxyphenyl) -1-methyl-1 ethyl-1,3,5 benzene ("Tris-TC" from Mitsui Petrochemical). I1 is suitable

  however, in general, that the proportion of the radicals

  droxy from a triphenol or a polyphenol does not exceed 30%, and the remaining hydroxy radicals belong to a diphenol. Novolacs derived from phenol and those derived from cresols are generally not suitable as phenolic hardeners for the mixtures according to the invention. It goes without saying that, when both diphenols and tri- or polyphenols are used, the amount of the total phenolic hardener (c) is chosen from

  in all, in the mixture in accordance with the

  from 0.7 to 1.2 equivalents of hydroxy of the phenols used per equivalent of epoxy epoxy resins put

stake.

  As accelerators (d) for hard mixtures

  cissables are suitable all the compounds that the skilled person knows well for accelerating the crosslinking of epoxy resins by phenolic hardeners,

  tertiary amines, their salts and their

  quaternary ammonium compounds, such as

  tetramethylammonium, phosphonium salts, alcohols

  alkali metal lates, such as sodium hexane-triolate, Lewis acids, such as BF and SnC14, nitrogen-containing heterocyclic compounds, such as pyridines, imidazoles and their derivatives. Imidazoles and

  N-acyl imidazoles (imidazolides) are particularly suitable

  well as accelerators (d).

  Suitable imidazoles include, for example, the compounds of formula III:

R1 (_R2

26 1 8 4 4 3

  wherein R1 R2 and R3 each represent independently

  hydrogen, C1-C12 alkyl, C5-C10 cycloalkyl or C6-C10 aryl. 2-methyl-2-ethyl-2-phenyl and 2-ethyl-4-methyl-imidazoles are particularly preferred. Suitable N-acyl imidazoles (imidazolides) include, for example, the compounds described in US Pat. Nos. 4,436,892 and 4,587,311 and JP A 74/7599. Particularly suitable compounds are those which correspond to formula IV:

R / 3 R4

R7 \ Y

  in which R to R have the meanings indicated below.

4 8

  above and R to R represent each independently

  hydrogen, C1-C12 alkyl, halogen,

  gene, nitro or trifluoromethyl. Examples of imidazolides which may be mentioned include (2,4,6-trimethylbenzoyl) -1-ethyl-2-imidazole, (2,6-dichloro-2-benzoyl) -methyl-2-imidazole and 2,4,6-trimethylbenzoyl. ) -methyl-2 imidazole and the

  (2,4,6-trimethylbenzoyl) -1-phenyl-2-imidazole.

  In addition to the components (a) to (d) the

  curable diapers according to the invention may contain

  if it is considered advantageous, (e) from 10 to parts by weight, preferably from 20 to 130 or more preferably from 80 to 120 parts by weight, per 100 parts by weight.

  weight of the components (a) to (c) of a thermoplastic material

  having a glass transition temperature of at least 180 ° C. The cured products which have been manufactured with the thermoplastic-containing mixtures are distinguished by excellent thermal and thermal properties.

  in particular by high dimensional stability.

  thermal resistance, by breaking strength, a

  flexural strength and flexural resilience re-

  as well as by a very great extensibility.

  As thermoplastic materials (e), it is possible to envisage, in the curable mixtures according to the invention, all the known polymers which have a time

  sufficiently high glass transition temperature, that is

  that is greater than or equal to 180 ° C., and which are miscible with the epoxy resin / hardener system according to the invention. In particular, they will be used as thermoplastics, taking into account their properties,

  polyamide-imides, polysulfones or polyether-

  sulphones and more especially polyimides or poly-

  ether-imides. We then especially appreciate the thermal materials

  moplastics which have a glass transition temperature (T) of from 180 to 350.degree. C., especially from 190 to 250.degree. C. The g.sub.T will in particular be between 220 and 250.degree. C. in the case of polyetherimides, and from 280 to 250.degree. 340 C in the case of polyimides. Polysulfones which can be used as thermoplastics include in particular

  the compounds which are described as polysulfo-

  (c) in EP A 194-232. These compounds can be found in

  for example, "Polysulfone Udel P1800", "Pol-ysulfone 2300" and "Polysulfone 3500" (Union Carbide Corporation). As component (e) it is also possible to use, in accordance with the invention, mixtures of 2 or more

2 thermoplastics.

  Thermoplastics (e) may very well also be polyimides, in particular: polyimides with phenylindan units, such as those described in US Pat. No. 3,856,752 and in EP A 92,524, in particular those who have a temperature of

  glass transition of about 305 C and a molecular mass

  (R) average average of about 65,000, for example Matrimid (R) 5218 from Ciba-Geigy, homopolyimides and copolyimides derived from at least one aromatic tetracarboxylic acid and at least one aromatic diamine, such as US Pat. No. 4,629,777 discloses, and homopolyimides and copolyimides such as those described, for example, in EP A 162 017, EP A 181 837, and US Pat.

and US Patent 4,629,685.

  Among the good thermoplastic materials (e) polyether-imides can also be included, such as General Electric products which are sold under the name Ultem (R) (eg Ultem (R) 1000). Polyethersulfones, such as Victrex PES 100 P from ICI, are also highly appreciated as thermoplastic materials.

and Udel P 1800 from Union Carbide.

  The compounds described in US Patents

  3,894,114, 3,948,835, 3,926,911 and 3,950,408 are examples of

  polyamide-imide plies which are suitable.

  The components (a) to (e) used in the mixtures according to the invention are all compounds

  known, and they can be prepared in a known manner.

  Of the curable mixtures according to the invention, those which contain: from 10 to 60 parts by weight of the epoxy resin (a), 90 to 40 parts by weight of the epoxy resin (b), and those containing amount of diphenol (c) such that there is from 0.8 to 1.1, preferably from 0.9 to 1.0, hydroxy equivalent of diphenol per epoxy equivalent of resins (a) and (b) ), and - from 0.1 to 1% by weight of the accelerator (d) relative to

to the quantity of (a) and (b).

  Mixtures according to

  the invention by carefully mixing all

  or dissolving them into each other, the various components being able to be introduced in different orders. When the mixtures also contain a thermoplastic material it is possible to dissolve it, for example by heating, in the epoxy resin and in the phenolic hardener, and after cooling, the accelerator can be added and possibly. other additives. However, it is also possible to prepare a solution of the thermoplastic material in an inert solvent, such as

  methylene chloride, and mix with methylene

  a mixture of epoxy resins and hardener.

  The mixtures according to the invention can have various applications. They are suitable, for example, as casting resins, as laminate resins or as

  impregnating resins, as molding materials, as

  sealing materials, as embedding materials and insulation for electrical engineering, and especially as adhesives and resins for use as dies for composite materials, especially for the manufacture

  of plastics reinforced with fibers.

  We can, if we wish, more particularly

  when changing agents are used at the same time

  Therefore, dissolve mixtures according to the invention in an organic solvent such as toluene, xylenes, methyl ethyl ketone, methylene chloride or any of the like solvents or solvent mixtures of which

  Usually used in the paint and varnish industry.

  Such solutions are especially suitable as im-

  Pregnancy or coating products.

  In addition, mixtures with

  cissables according to the invention, at any stage prior to hardening, customary modifying agents,

  including thinners, fillers, reinforcing agents

  cement, pigments, dyes, organic solvents, plasticizers, leveling agents,

  thixotropy of flame retardants or release agents.

  The diluents, reinforcing agents, fillers and pigments which can be used in the curable mixtures according to the invention are in particular liquid coumarone-indene resins, textile fibers,

2618 4 4 3

  glass fibers, asbestos fibers, boron fibers, carbon fibers, polyethylene powder, polypropylene powder, quartz flour, mineral silicates, such as mica, flour, asbestos, slate flour or kaolin, chalk flour, antimony trioxide, montmorillonite (Bentone), lithopone, barytite, titanium dioxide, carbon black, graphite, color oxides such as iron oxide, or metal powders, such as powder

  of aluminum or iron powder. When mixtures

  forms of the invention are to be used to

  impregnated it is particularly advantageous to add

short fibers.

  As leveling agents to be added to

  hardenable mixtures, especially when they have to

  vir to protect surfaces, we can use for example

  silicones, liquid acrylic resins, acetic acid

  cellulose butyrate, polv- (vinylbutyral), waxes, stearates, etc ... (these can also be used

release agents).

  As plasticizers it is possible to use, for modifying hardenable mixtures, for example phthalate

  of dibutyl, dioctyl phthalate, dibutyl phthalate

  nyle, tricresyl phosphate, tri-xyl phosphate

  nyl and diphenoxyethyl-formal.

  To harden mixtures according to the

  vention it is good to heat them to a

  between 120.degree. C. and 250.degree. C., more particularly between 160.degree. and 220.degree. C. The curing, as is known, can also be carried out in two or more stages, the first at a lower temperature than the one or more following. If desired, it is possible to add to the curable mixtures, to lower their viscosity,

  active diluents, such as the diglycidyl ether of neopen

  tyl-glycol, butane-diol or hexane-diol.

  The invention also relates to the application

  cation of the mixtures according to the invention to the manufacture

  cured molded articles and their application to the manufacture of prepregs for fiber-reinforced composite materials or the manufacture of adhesive films. Prepregs and adhesive films may be manufactured in a known manner, for example by the impregnation process in the presence of one of the solvents mentioned above or a halogenated solvent such as methylene chloride, or by the melting process

hot said "hot melt".

  The molded articles according to the invention are generally indicated by high temperatures of

  transition, and at the same time by good

mechanical sistances.

  The following examples illustrate the invention.

  The components (a) to (e) used in the examples are as follows: epoxy epoxy resin epoxy phenolic novolak which has a functionality of 3.6, an epoxy content of 5.6 equivalents / kg

  and a viscosity of about 40 Pa.s at 50 C.

Epoxydic resin a2

  Tetramethyl-2,2-tetraglycidyl ether, -

  6.6 cyclohexanol (prepared according to Example 2 of US Pat.

  4,549,008) which has an epoxy equivalent weight of 129.

  Epoxidic resin a3 Triglycidyl-bis-hydantoin of formula VI: ## STR2 ## wherein: ## STR5 ## CH2 (VI) ICH

2618 4 4 3

  which has an epoxy content of 5.6 equivalents / kg and a screw

cosity of about 13 Pa.s at 80 C.

  Epoxy epoxy resin epoxy, liquid at room temperature, which has a functionality of 2.2, an epoxy content of 5.7 equivalents / kg and a viscosity

from 1.4 Pa.s to 500 C.

  Epoxy b2 diglycidyl ether bis-phenol F having an epoxy content of 6.1 equivalents / kg and a viscosity

from 6.0 Pa.s to 25 C.

  Polvimide 1 Phenyl-indane polyimide having a glass transition temperature of 305 C and an average molecular weight of about 65,000 (Matrimid (R)

5218, from Ciba-Geigy).

  Polyether-imide 1 Polyether-imide which contains repeating units of formula:

[_. /.// / \\ _-

  and which has a glass transition temperature of 219 C

  (Ultem (R) 1000 from General Electric).

Polvsulfone 1

* Polysulfone Udel P1800 (R) (Union Carbide Cor-

  poration) which has a melting point between 350 and 370 C,

2618 4 4 3

  a dimensional stability under heat (according to ASTM D 648) of 175 ° C., a glass transition temperature of 200 ° C. and a molecular weight range of about 22,000 to 10,000.

EXAMPLE i

  a) 15 g of the epoxy resin and 85 g of the epoxy resin b1 are mixed at 120.degree. At this temperature, 17.7 g of 2,6-dihydroxy-toluene and 17.7 g of 2,7-dihydroxy naphthalene are added and dissolved while stirring. After cooling the mixture to 80 ° C., 0.1 g of 2-phenylimidazole are added thereto. After cooling to room temperature, a solution is added to the mixture.

  81.2 g of the polyimide 1 in 82 g of methyl chloride

  and stir well until a homogeneous mixture is formed. By means of a rake, the mixture is cast on a silicone paper so as to produce a film

  0.1 mm thick and the solvent is evaporated off.

  at room temperature. We superimpose several

  30 x 30 mm pellets, the whole is press-molded at 1800C so as to produce a molded article of

  1 mm thick and cured at 180 ° C. for 1 hour. Lob-

  molded jet has a Tg, determined by ATM (thermomechanical analysis), of 142 C and a secondary transition temperature of C. b) Example 1a is repeated but using 4 g of polyamide 1 as thermoplastic material: after

  hardening we find a T of 153 and 182 C.

g

EXAMPLE 2

  Example 1a) is repeated, but using 44.7 g of polysulfone 1 as thermoplastic material: after curing, a T of 164 ° C. with a g

pre-softening at 960C.

EXAMPLE 3

  a) 35 g of the epoxy resin a2 and 65 g of the epoxy resin b2 are mixed at 120 ° C. with 20.5 g

  2,6-dihydroxytoluene and 20.5 g of 2,7-dihydroxy-naphtha

  Talene. 0.1 g of 2-phenylimidazole are added, the mixture is cooled to room temperature, then, using the procedure described in Example 1, 84.5 g of polyimide 1 are added thereto.

  methylene chloride and proceed to the implementation.

  After curing, there is a 194 C T with a g

  low pre-softening at 104 C.

  (b) A composition identical to

  that described under (a) but with 60,4 g of the poly-

  imide 1 and is carried out also as under a): a laminated molded object having a T of 210 and 105 ° C is obtained. With one part of the film two aluminum plates are glued together at 180 ° C. and performs a complementary hardening at 200 C for 1 hour. The cured resin has a fracture toughness (Gic) of 794 J / m 2, as measured by the double twist test according to "Journal of Materials Science, 10, 1334 (1975) and

  14, 776, (1979). "For this we stick with the hard

  two extrudal 050 aluminum plates (AlMgSi 0.5) of dimensions 200 x 20 x 5 mm, which have been treated with a sulphochromic mixture, and the adhesive is cured.

  applying a slight pressure. In this method one

  the propagation of the crack in the bonding, more precisely we measure, starting from the maximum load for

  the propagation of the crack, the breaking energy in J / m2.

EXAMPLE 4

  By operating as in Example 1, it is mixed

  g of the epoxy resin a3 and 30 g of the epoxy resin

  xydique b2 with 19 g of 2,6-dihydroxytoluene, 19 g of 2,7-dihydroxy naphthalene, 0.1 g of 2-phenylimidazole and

  138 g of polyether-imide 1 and is carried out.

  After hardening, there is a T 188 C with g

  a slight pre-softening at 100 C.

EXAMPLE 5

  a) Operating as in Example 3a, use is made of 35 g of epoxy resin a2, 65 g of epoxy resin b2, 22 g of 2,6-dihydroxytoluene, and 22 g of 2,7-dihydroxy naphthalene. 0.1 g of (2,4,6-trimethyl)

  benzoyl) -1-phenyl-2 imidazole and 96 g of polyimide 1.

  After a hardening of 1 hour at 180 C and 1 hour at

2000 We find a T of 212 C.

  (b) Repeat the test but using 71 g

  polyimide 1: there is a T of 222 C (slight pre-ra-

  softening at 100 ° C) and fracture toughness GiC

  (double twist test) 976 J / m2.

EXAMPLE 6

  a) Using the procedure described in Example 1, 15 g of the epoxy resin a1, B5 g of the epoxy resin b1, 17.7 g of 2,7-dihydroxytoluene and 17.7 g of dihydroxy are used. -2.7 naphthalene and a solution of 0.1 g of 2-phenylimidazole and 44.7 g of polysulfone 1, and cured at 180 ° C for 2 hours. The molded object hardens

  at a T of 1640C with a pre-softening at 96 C.

  b) Repeat the test but using BO, 4 g of polyimide 1 instead of polysulfone. The molded object

cured then has a T of 142 C.

g

EXAMPLE 7

  By operating as described in Example 1, 100 g of a mixture consisting of 35 parts by weight of the epoxy resin and 65 parts by weight of the epoxy resin bl, of 20.5 parts, are used and cured. by weight of 2,6-dihydroxytoluene, 20.5 parts by weight of 2,7-dihydroxy naphthalene, 0.2 part by weight of (2,4,6-triinylbenzoyl) -1-phenylimidazole and 80 parts by weight of , 4 g of polyimide 1. The hardened molded object has a T of 194 C and g

  a slight pre-softening at 101 C.

EXAMPLE 8

  By operating according to example 1,

  33.3 g of the epoxy resin a2, 33.3 g of the epoxy resin b1, 33.3 g of the epoxy resin b2, 45.9 g

  of 2,7-dihydroxy naphthalene and 0.1 g of 2-phenylimidazole.

  The hardened molded objects have the following properties:

T (ATM) = 1220C

  g Flexural strength (ISO 178) = 152 MPa Marginal elongation (ISO 178) = 6.9 'Resistance to impact bending (ISO R 179) = 38 kJ / m'

EXAMPLE 9

  a) By operating as in Example 1, 50 g of the epoxy resin a2 and 50 g of the resin are used.

  b2 epoxide, 21 g of 2,6-dihydroxytoluene, 21 g of dihydrogen

  2,7-hydroxy-naphthalene and 0.1 g of 2-phenylimidazole. The hardened molded objects have the following properties:

T (ATM) = 113 C

  g Flexural strength (ISO 178) = 140 MPa Marginal elongation (ISO 178) = 12.1% Impact resistance (ISO R 179) = 68 kJ / m2 b) The test is repeated but using,

  phenolic hardener, 17.5 g of 2,6-dihydroxy-

  luene and 17.5 g of 2,7-dihydroxy naphthalene. The hardened molded objects have the following properties:

T (ATM) = 960C

  Flexural strength (ISg 178) = 140 MPa Flexural strength (ISO 178) = 140 MPa

2618 4 43

  Marginal elongation (150 178) => 14% Resistance to impact bending (ISO R 179) = 67 kJ / m2

EXAMPLE 10

  a) Operating as described in Example 1, use is made of 35 g of the epoxy resin a2, 65 g of the epoxy resin b2, 20.5 g of 2,6-dihydroxytoluene and 20.5 g of dihydroxy- 2.7 naphthalene. The hardened molded objects have the following properties:

T (ATM) = 106 C

  g Flexural strength (ISO 178) = 151 MPa Marginal elongation (ISO 178) => 13% Impact resistance (ISO R 179) = 91 kJ / m2 Tensile strength (double twist test) = 454 J / m2

EXAMPLE 11

  15 g of the epoxy resin are heated to 120.degree.

  xydic acid and 85 g of the epoxy resin b1, a mixture of 17.7 g of 2,6-dihydroxytoluene and 17.7 g of 2,7-dihydroxy naphthalene is added and the mixture is homogenized. After cooling to 80 ° C., 0.1 g of 2-phenylimidazole is added and, to remove the air bubbles, the mixture is placed under reduced pressure for a short time. At 70 ° C the mixture has a viscosity

  r of 310 mPa.s. Part of the mixture is used to

  to measure fracture toughness by the double twist test.

  The majority of the mixture is cast in Extrudal 050 molds (AlMgSi 0.5) having the dimensions 80 × 60 × 4 mm, and cured for 2 hours at 140 ° C. and for 2 hours at 180 ° C. The results are obtained. following: T (ATM) = 105oC g Flexural strength (ISO 178) = 128 MPa Marginal elongation (ISO 178) => 14% Impact resistance (ISO R 179) = 86 kJ / m2 Tensile strength (double twist test) = 726 J / m2 After having been stored for 2 weeks at room temperature, the resinous mixture is still

good tack ("tack").

EXAMPLE 12

  a) Example 11 is repeated but using 3 g of 2,7-dihydroxy naphthalene as hardener. Molded objects are obtained which have the following properties:

T (ATM) = 120 C

  g Flexural strength (ISO 178) = 145 MPa Marginal elongation (ISO 178) = 13% Impact resistance (ISO R 179) = 86 kJ / m2 b) Example 11 is repeated, but using,

  20.3 g of bis-phenol A and 20.3 g of dihy-

  droxy-2,7 naphthalene. Molded objects are obtained which have the following properties:

T (ATM) = 94 C

  g Flexural strength (ISO 178) = 125 MPa Marginal elongation (ISO 178) => 14% Impact resistance (ISO R 179) = 84 kJ / m2 Tensile strength (double twist test) = 783 J / m2

EXAMPLE 13

  By operating as in Example 11, 50 g of the epoxy resin a3, 50 g of the epoxy resin b1, 42.1 g of 2,7-dihydroxynaphthalene and 0.1 g of 2-phenylimidazole are used. Molded objects are obtained which have the following properties:

T (ATM) = 1330C

  g Flexural strength (ISO 178) = 158 MPa Marginal elongation (ISO 178) = 12% Impact resistance (ISO R 179) = 53 kJ / m2

EXAMPLE 14

  By operating as in Example 11, 20 g of the epoxy resin al, 20 g of the epoxy resin a3, 60 g of the epoxy resin b2, 19.5 g of 2,6-dihydroxytoluene, 19 are used. 5 g of 2,7-dihydroxy naphthalene and 0.1 g of 2-phenylimidazole. Molded objects are obtained which have the following properties:

T (ATM) = 1070C

  g Flexural strength (ISO 178) = 153 MPa Marginal elongation (ISO 178) => 14 Impact bending strength (ISO R 179) = 44 kJ / m2

EXAMPLE 15

  15 g of the epoxy resin are heated to 140.degree.

  dique ai and 85 g of the epoxy resin bl and mix well. To this mixture of resins is added, while stirring,

  45 g of a mixture of 22.5 g of dihydroxy-4,4'-diphenyl-

  sulfone, 11.25 g 2,6-dihydroxytoluene and 11.25 g

  of 2,7-dihydroxy naphthalene (melted mixture of the three

  nols, cooled). After cooling the mixture to 90 ° C., 0.1 g of 2-phenylimidazole is added thereto and poured into molds having dimensions of 80 × 60 × 4 mm. After hardening for 16 hours at 160 ° C., the following properties are measured on the molded articles:

T (ATM) = 113 C

  Flexural strength (ISO 178-) = 148 MPa Marginal elongation (ISO 178) = 8.9% Impact resistance (ISO R 179) = 27 kJ / m2

EXAMPLE 16

  Example 15 is repeated, but with a resin mixture consisting of 35 g of the epoxy resin a2 and 65 g of the epoxy resin b2 and with a mixture of 25.5 g of 4,4-dihydroxy-4-diphenylsulfone, of 12, 75 g of

  2,6-dihydroxytoluene and 12.75 g of 2,7-dihydroxy-naphtha

  Talene. The hardened molded objects have the following properties:

lowing:

T (ATM) = 1080C

  g Flexural strength (ISO 178) = 153 MPa Marginal elongation (ISD 178) = 8.1% Impact resistance (ISO R 179) = 26 kJ / m2

EXAMPLE 17

  To the resinous mixture of Example 15 is added

  a mixture (melted solidified mixture) of 20.25 g of dihydro-

  xy-4,4'-biphenyl, 10.125 g of 2,6-dihydroxytoluene and

  10.125 g of 2,7-dihydroxy naphthalene. After having

  killed the implementation as in example 15 one obtains molded objects which have the following properties:

T (ATM) = 1090C

  g Flexural strength (ISO 178) = 154 MPa Marginal elongation (ISO 178) = 12.9% Impact resistance (ISO R 179) = 72 kJ / m2

EXAMPLE 18

  To a resinous mixture identical to that of Example 16 is added a mixture of 23.25 g of 4,4'-dihydroxybiphenyl, 11.625 g of dihydroxy-2,6-toluene and 11.625 g of 2,7-dihydroxy naphthalene. After carrying out the implementation as in Example 15, molded articles having the following properties are obtained: Tg (ATM) = 109 C. Flexural strength (ISO 178) = 153 MPa Marginal elongation (ISO 178) = 11 , 2% Impact resistance (ISO R 179) = 78 kJ / m2 EXAMPLES 19 and 20: Laminate production

EXAMPLE 19

  146.3 g of polyimide 1 are dissolved in 300 g of methylene chloride and then 40 g of the resin are added.

  epoxide A2 and 60 g of the epoxy resin bl. To the mix

  homogeneous mixture is slowly added dropwise a solution of 46.3 g of 2,6-dihydroxy-naphthalene and 0.1 g of 2-ethyl-4-methylimidazole in 50 g of methyl ethyl ketone. With this solution, a nearly unidirectional carbon fiber fabric (G 827, Brochier SA) was impregnated at 3 'by weight of glass fibers in the weft direction and then dried at 50 ° C. for 16 hours. After having treated them at 900C under reduced pressure for 30 minutes, the prepregs were stacked in 11 superimposed layers and the whole was compressed at 2000C for 2 hours at 8 bar in order to produce a laminate. The following results are obtained:

T (ATM) = 2260C

  Fiber content = 80.6% by weight Interlaminar shear strength (ASTM 2344) = 60 MPa

EXAMPLE 20

  With the same solution as in Example 19 and

  with T300 carbon fiber (Toray) a pre-fabricated

  unidirectional impregnated (resin content: 37% by weight) by winding on a drum. After having treated them at 90 ° C. under reduced pressure (50 mbar) for 30 minutes, the prepregs (10 layers) are stacked on top of each other and the whole is compressed for 1 hour at 2000 ° C.

  under 10 bar so as to produce a unidirectional laminate

  tional. This laminate is then subjected to additional hardening for 1 hour at 200 ° C. and for 1 hour at 210 ° C. The following properties are found:

T (ATM) 225 C

  g Flexural strength (parallel to the fiber) (ISO 178) = 1350 MPa

  Flexural strength (perpendicular-

  to fiber) (ISO 178) = 85 MPa

  Marginal elongation of fibers (parallel

  same as fiber) (ISO 178) = 1.3%

  Marginal elongation of fibers

  pendicular to the fiber) (ISO 178) = 1.3%

EXAMPLE 21

  149 g of the polyetherimide 1 are dissolved in 2.50 g of methylene chloride, then 50 g of the epoxy resin a2 and 50 g of the epoxy resin b2 are added.

  and mix well. After having removed the solvent by

  until there is only about 10 D left in, 49 g of

  2,7-dihydroxy naphthalene and 0.1 g of 2-ethyl-4-methylimidazole

  dazole in solution in methyl ethyl ketone (50%).

  With this mixture a film is made on a paper

  silicone and dried for 12 hours at 50 ° C. (without reduction

  pressure) and for 30 minutes at 90 ° C under reduced pressure. The film is then cut and made into a simple resin wafer by molding in a laboratory press at a press temperature of 2000 ° C. for 2 minutes. After curing in the oven at 200 C for 2 hours

  the molded object has a T (ATM) of 160 C.

g

Claims (17)

  A storage-stable, curable mixture which contains: a) from 10 to 80 parts by weight of an epoxy resin having a functionality of at least 3, b) from 90 to 20 parts by weight of an epoxy resin having a functionality of 2 to 2.5, c) a diphenol whose quantity is chosen in such a way   that there is, by epoxy equivalent, epoxy resins   xydiques (a) and (b), from 0.7 to 1.2 equivalents of hydroxyl O10 of diphenol (c), this dihydric phenol consisting of: cl) from 0 to 80% by weight of a compound corresponding to one of formulas I and II: ## STR2 ## 1 - (II) OH.OH wherein T represents the direct bond, methylene, isopropylidene, O, S, CO or SO and R represents hydrogen or C 1 -C 4 alkyl and c 2) from 100 to 20% by weight of a dihydroxy-naphthalene, as well as   d) from 0.05 to 5% by weight, based on the epoxy resins   diques (a) and (b), an accelerator.   2. Mixture according to claim 1 wherein the epoxy resins (a) and (b) have a content   in epoxy of 5 to 11 equivalents / kg and are glycol ethers.   cidyl esters, glycidyl esters or N-gly-   cidylics of cycloaliphatic, aromatic or heterocyclic.   3. Mixture according to claim 1 in   which the epoxy resins (a) and (b) are naphtha   epoxidized compounds or glycidyl derivatives of bis-phenols,   hydantoins or tetramethylol-cyclohexanes.   The blend of claim 1 wherein the epoxy resin (a) has a functionality of 3 to 4 and is an epoxidized phenolic novolak or a derivative thereof   glycidyl of a hydantoin or a tetramethylol-cyclohexyl   hexane. The blend of claim 1 wherein the epoxy resin (b) has a functionality of 2 to 2.2 and is an epoxidized phenolic novolak or a glycidyl derivative of bis-phenol A or bisphenol F. Mixture according to claim 1 in   wherein the hydroxy radicals of the compound of formula I occupy   positions 4 and 4 ', and the symbol T represents 0,   5S, methylene or isopropylidene.   7. Mixture according to claim 1 in   wherein the compound of formula II is dihydroxytoluene.   8. The blend of claim 1 wherein the component (c2) is 2,6-dihydroxy naphthalene or 2,7-dihydroxy naphthalene.   9. The mixture of claim 1 wherein the diphenol (c) consists of 50% by weight of the component (cl) and 50% by weight of the component (c2). 10. Mixture according to claim 1 wherein the diphenol (c) is constituted by 2,6-dihydroxy   toluene and 2,7-dihydroxy naphthalene.   11. Mixture according to claim 1 in   accelerator (d) is an imidazole or an N-acyl   imidazole. 12. Mixture according to claim 1 which, in addition to the components (a) to (d), contains (e) from 10 to   parts by weight, per 100 parts by weight of the   (a) to (c), of a thermoplastic material which has a   glass transition temperature of at least 180qC.   13. Mixture according to claim 12 wherein the thermoplastic material (e) is a polyimide, a polyetherimide, a polyamideimide, a polysulfone or a polyether-sulfone, and has a transition temperature glassy from 180 to 3500C.   Mixture according to claim 1 which   contains from 10 to 60 parts by weight of the epoxy resin   from 90 to 40 parts by weight of the epoxy resin   xydic acid (b), a quantity of diphenol (c) such that there   from 0.8 to 1.1 equivalents of hydroxy of diphenol per   epoxy resins (a) and (b), and from 0.1 to 1% by weight of the accelerator (d) relative to the amount of (a) and (b).   15. Application of the mixture according to the   1 to the manufacture of hardened molded articles.   16. Application of the mixture according to the   1 for the manufacture of prepregs for fiber-reinforced composite materials, or the manufacture of adhesive films.   17. Hardener for epoxy resins that   contains a compound of formula I or II according to the 1 and dihydroxy-naphthalene.