SI9200114A - Curable epoxy resin composition containing a blocked accelerator - Google Patents

Abstract

Curable compositions containing (a) an epoxy resin, (b) a tertiary amine or an imidazole compound, and (c) up to 30% by weight, based on the proportion of component (a), of a polycarboxylic anhydride, are suitable for the production of flexible prepregs having a long shelf life. The prepregs can be cured at relatively low temperatures of 65-100 DEG C.

Description

EP-A 429 395 describes the preparation of prepregs from a mixture of epoxy resins containing a latent curing agent, a primary or secondary amine and mercaptan, characterized by high storage stability. Hardening these prepregs, however, requires relatively high temperatures> 100 ° C.

In order to achieve final curing at about 100 ° C, the crosslinking reaction must be catalyzed.

Tertiary amines are commonly used as a hardening accelerator for the crosslinking reaction with a latent hardener (C-step formation). Tertiary amines, however, catalyze not only the reaction with a latent curing agent at higher temperatures, but also the homopolymerisation of the epoxide and the reaction with the Curing agent of B-steps already at room temperature, which results in insufficient storage stability of the epoxy resin mixture - curing agents or. prepregs.

In order to achieve sufficient stability, the accelerators must be locked in such a way that it is effective only at elevated temperatures.

DE patent file 2 139 290 proposes boron trichloride adducts of tertiary amines as accelerators for the hardening of epoxy resins with latent hardeners. The prepregs made from such compositions, however, do not meet today's requirements for flexibility and stickiness.

DE-OS 3 440 362 describes curable compositions containing a polyamine / carboxylic acid metabolic product as a latent curing agent. However, the storage stability of such mixtures is still insufficient for a particular use.

We have now developed a binder of epoxy resin, which, as a hardening accelerator, contains a tertiary amine whose catalytic effect is blocked by the addition of polycarboxylic acid anhydride, which results in high stability at room temperature of the curing mixture. When heated to about 80-100 ° C, a free amine is formed which catalyzes either the homopolymerisation of the epoxy resin or, in the case of a mixture containing another curing agent or a lethal curing agent, a crosslinking reaction. In this way, prepregs can be prepared which are stored without noticeable deterioration of their properties for up to 3 weeks at room temperature and up to 1 month at 5 ° C and can be hardened at relatively low temperatures from about 65-100 ° C in the shortest time.

The subject of the present invention are curable compositions comprising (a) epoxy resin (b) a tertiary amine or imidazole compound and (c) up to 30% by weight of polycarboxylic acid anhydride relative to the proportion of component (a).

Preferably, the compositions of the invention contain 1-20% by weight, in particular 2-15% by weight of component (c) by proportion of component (a).

As the epoxy resin (a) of the mixture of the substance of the invention, any epoxy conventional in the epoxy resin technique can be used in principle.

Examples of epoxy resins are:

I) Polyglycidyl- and poly ((3-methylglycidyl) esters obtained by the metabolism of a compound with at least two carboxylic groups in a molecule and epichlorohydrin, respectively. / 3-methylpichlorohydrin. The metabolism is efficiently carried out in the presence of bases.

As a compound with at least two carboxylic groups in the molecule, aliphatic polycarboxylic acids can be used. Examples of these polycarboxylic acids are oxalic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, cork acid, azelaic acid or dimerized or. trimerized linoleic acid.

Alternatively, cycloaliphatic polycarboxylic acids, such as e.g. tetrahydro phthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid or 4-methylhexahydrophthalic acid.

Further, aromatic polycarboxylic acids such as e.g. phthalic acid, isophthalic acid or terephthalic acid.

II) Polyglycidyl- or polyQ3-methylglycedyl) ethers obtained by the reaction of a compound with at least two free alcohol hydroxy groups and / or phenolic hydroxy groups and epichlorohydrin or / 3-methylpichlorohydrin under alkaline conditions or in the presence of an acid catalyst.

Ether of this type is carried out e.g. from acyclic alcohols such as ethylene glycol, diethylene glycol, and higher poly (oxyethylene) glycols, propane-1,2-diol or poly (oxypropylene) glycols, propane-1,3-diol, butane-1,4-diol, poly (oxytetramethylene) glycols, pentane-1,5diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerin, 1,1,1-trimethylolpropane, pentaerythritol or sorbitol, as well as from polyepichlorhydrin.

They can also be performed e.g. from cycloaliphatic alcohols such as 1,4-cyclohexanedimethanol, bis (4-hydroxycyclohexyl) methane or 2,2-bis (4-hydroxycyclohexyl) propane ah have aromatic nuclei such as e.g. N, N-bis (2-hydroxyethyl) aniline or p, p'bis (2-hydroxyethylamino) diphenylmethane.

Epoxy compounds can also be derived from single-core phenols, such as e.g. from resorcinol or hydroquinone; or based on phenols with multiple nuclei, such as e.g. 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 or 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, as well as from novolacs obtained by condensation of aldehydes, _f . ) as formaldehyde, acetaldehyde, chloral mi-furfuraldehyde with phenols, such as phenol, or with phenols which are substituted in the nucleus by chlorine atoms or C1-C4-alkyl groups, such as e.g. 4-chlorophenol, 2-methylphenol or 4-tert.butylphenol or by condensation with bisphenols as described above.

III) Poly (N-glycidyl) compounds obtained by the dehydrochlorination of reaction products of epichlorohydrin with amines containing at least 2 amine hydrogen atoms. These amines are, e.g. aniline, n-butylamine, bis (4-aminophenyl) methane, m-xylylenediamine or bis (4methylaminophenyl) methane.

Poly (N-glycidyl) compounds also include triglycidylisocyanurate, N, N'-diglycidyl derivatives of cycloalkylene urea, such as ethylene urea or 1,3-propylene urea, and diglycidyl derivatives of hydantoins, such as 5,5-dimethylhydantoin.

IV) Poly (S-glycidyl) compounds, e.g. di-S-glycidylderivates derived from dithiols, such as e.g. ethane-1,2-dithiol or bis (4-mercaptomethylphenyl) ether.

V) Cycloaliphatic epoxy resins, e.g. bis (2,3-epoxycyclopentyl) ether, 2,3epoxycyclopentylglycidylether, 1,2,2-bis (2,3-epoxycyclopentyloxy) ethane or 3,4epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate.

Epoxy resins may also be used in which 1,2-epoxy groups are bonded to different heteroatoms. functional groups; these compounds include e.g. 4-Aminophenol, Ν, Ο-Triglycidylderivate, salicylic acid glycidylether-glycidyl ester, N-glycidyl-N '- (2-glycidyloxypropyl) -5,5-dimethylhydantoin or 2-glycidyloxy-1,3-bis (5,5-dimethyl- 1-glycidylhydantoin-3-yl) propane.

Preferably, epoxy resins having an epoxy content of from 2 to 10 equivalents per kg are used, which are glycidylethers, glycidyl esters or N-glycidylders of aromatic, heterocyclic, cycloaliphatic or aliphatic compounds.

I

The epoxy resins used are preferably liquid, i.e. that they are either liquid resins or liquid mixtures of solid and liquid resins.

Particularly preferred as epoxy resins are diglycidyl ethers of bisphenols or epoxy novolacs.

p)

Most preferred as epoxy resins sp diglycidyl ethers of bisphenol A or bisphenol F.

As a component (b) of the compositions of the invention, any tertiary amine or imidazole known in the art of accelerating hardening can be used in principle.

When used as component (b), the tertiary amine may be an aliphatic, cycloaliphatic, aromatic or heterocyclic amine with at least one tertiary nitrogen atom.

The tertiary amines required for use according to the invention may, in addition to one or more tertiary amino groups, also contain one or more primary or secondary amino groups, hydroxyl groups or heteroatoms such as oxygen, phosphorus or sulfur.

Examples of suitable tertiary amines are trimethylamine, triethylamine, tri-n-propylamine, tri-n-butylamine, benzyldimethylamine, triphenylamine, phenyldimethylamine, phenyldiethylamine, cyclohexyldimethylamine, cyclohexyldiethylamine, urotropin, triethylenediamine, N, N-dimethyl-thiamine, N, N-dimethyl-thiamine, N, N-dimethyl-thiamine, N, N-dimethyl-thiamine ethylenediamine, N, N-dimethyl-N '- (3-aminopropyl) ethylenediamine,

N, N-dimethyl-N ', N'-bis (3-aminopropyl) ethylenediamine, N, N-dimethyl-N' - (2-cyanoethyl) 1,3-diaminopropane, N, N-dimethyl-N '- ( 3-aminopropyl) -1,3-diaminopropane, N, N-dimethyl-N ', N'-bis (3-aminopropyl) -1,3-diaminopropane, bis (2-dimethylaminoethyl) ether, 2-dimethylaminoethyl-3-dimethylaminopropyl ether, 2,2-dimorpholinodiethylether, N-methoxyethylmorpholine, N-methylmorpholine, N-ethylmorpholine, N-methylpiperidine, N-ethylpiperidine, N, N-dimethylethanolamine, 2- (2-dimethylaminoethoxy) ethanol, N- (2-hydroxyethoxyethoxyethoxyethoxyethoxyethoxyethoxyethoxyethoxyethoxyethoxyethanol) , N, N, N-trimethyl-N-hydroxyethyl-bisaminoethyl ether, N, N-bis (3-dimethylaminopropyl) -N-isopropanolamine, N- (3-dimethylaminopropyl) -N, Ndiisopropanolamine, triethanolamine, Ν, Ν'-dimethylpiperazine , trimethylaminoethylpiperazine, N-methyl-2-azanorbornane, Ν, Ν, Ν ', ΝΤ'-pentamethyldiethylenetriamine, Ν, Ν, Ν', Ν'tetramethylhexamethylenediamine.

I

Preferably used in the compositions of the invention are tertiary amines containing two or more nitrogen atoms.

Particularly preferred are tertiary amines with two or three dialkylamino groups, such as e.g. N, N-dimethyl-N ', N'-bis (3-aminopropyl) ethylenediamine, N, N-dimethyl-N', N'-bis (3aminopropyl) -1,3-diaminopropane, bis (2-dimethylaminoethyl) ether , 2-dimethylaminoethyl 3-dimethylaminopropyl ether, 2,2-dimorpholinodiethyl ether, N, N, N-trimethyl-N-hydroxyethylbisaminoethyl ether, N, N-bis (3-dimethylaminopropyl) -N-isopropanolamine, N- (3dimethylaminopropyl) -N, N- diisopropanolamine, Ν, Ν, Ν ', Ν', Ν '' - pentamethyldiethylenetriamine and ri, Ν, Ν ', Ν'-tetramethylhexamethylenediamine.

Particularly preferred are 2-dimethylaminoethyl-3-dimethylaminopropyl ether, N, N'-dimethylpiperazine and Ν, Ν, Ν ', Ν', Ν '' - pentamethyldiethylenetriamine.

Further, as component (b) in the compositions of the invention, imidazole compounds such as e.g. imidazole, ethyl-, 2-phenyl-, 1-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole or 2-ethyl-4-methylimidazole.

Preferred imidazole compounds are 1-methylimidazole and 2-ethylimidazole.

To block the tertiary amine or imidazoles Any component of a polycarboxylic acid anhydride can be used as a component (c) of the compositions of the invention.

Preferably cycloaliphatic or aromatic di- or tetracarboxylic acid anhydrides are used.

Preferred anhydrides are phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, nadic anhydride, pyromelic acid anhydride, methyl-hexahydro-phthalic anhydride, and in particular methyltetrahydro-phthalic anhydride and methyl anhydride.

The quantitative ratios of the components of the compositions of the invention may vary over wide ranges. In general, 100 wt. .parts of epoxy resin about 1-20, preferably 1-10 parts by weight of component (b) and up to 30, preferably 1-20, especially preferably 2-15 parts by weight of component (c).

To prepare the prepregs, one or more curing agents can be added to the compositions of the invention as an additional component (d).

It is a further object of the present invention to provide curable compositions comprising (a) an epoxy resin (b) a tertiary amine or imidazole compound, (c) up to 30% by weight of polycarboxylic acid anhydride relative to the proportion of component (a) and (d) one or more hardeners for epoxy resin.

Preferably, component (d) is a so-called latent hardener, i.e. a hardener that first reacts at temperatures above about 80 ° C.

As a latent hardener, in principle any known compound that meets the definitions of the invention can be used, i.e. any compound that is inert to the epoxy resin below a defined limit temperature of 80 ° C but reacts quickly upon crosslinking of the resin as soon as that limit temperature is exceeded. The limit temperature according to the invention of the latent hardener used is preferably at least 85 ° C, in particular at least 100 ° C. Such compounds are well known and commercially available.

Examples of suitable latent curing agents are dicyandiamide, cyanoguanidine, e.g. compounds described in U.S. Patent 4,859,761 or EP-A 306,451, aromatic amines such as e.g. 4,4'7 or 3,3'-diaminodiphenylsulfone or guanidines, such as e.g. 1-o-tolylbiguanide or modified polyamines such as e.g. Ancamine® 2014 S (Anchor Chemical UK Limited, Manchester).

Further suitable curing agents are complex metal salts of imidazoles such as e.g. are described in US Patents 3,678,007 or 3,677,978, carboxylic acid hydrazides such as e.g. adipic acid hydrazide, isophthalic acid hydrazide or anthranilic acid hydrazide, triazine derivatives such as e.g. 2-phenyl-4,6-diamino-s-triazine (benzoguanamine) or 2lavril-4,6-diamino-s-triazine (laugvanamine) as well as melamine and its derivatives. The last fertilized compounds are described e.g. U.S. Patent No. 3,030,247.

I

Cyanacetyl compounds such as e.g. described in U.S. Patent 4,283,520 e.g. Neopentyl glycol biscyanacetic ester, cyanacetic acid N-isobutylamide, 1,6-hexamethylene-bis-cyanacetate or 1,4-cyclohexanedimethanol bis-cyanacetate.

)

Suitable latent curing agents are also compoundirfg ^ i-cyanacylamide, such as e.g. diamide N, N adductic acid N. Such compounds are described e.g. U.S. Patent Nos. 4,529,821, 4,550,203, and 4,618,712.

Further suitable latent hardeners disclosed acylthiopropylphenols in US patent 4,694,096 and those in US patent 3,386,955 disclosed urea derivatives such as e.g. toluene-2,4-bis (N, N-dimethylcarbamide).

Preferred latent curing agents are dicyandiamide, and in particular 4,4′-diaminodiphenylsulfone.

If appropriate, the mixture of the substance of the invention may further comprise further enhancers for the reaction of the epoxy resin with a latent hardener. Suitable accelerators co. urea derivatives such as

N, N-dimethyl-N '- (3-chloro-4-methylphenyl) urea (Chlortoluron),

N, N-dimethyl-N '- (4-chlorophenyl) urea (Monuron) or N, N-dimethyl-N' - (3,4-dichlorophenyl) urea (Diuron), 2,4-bis (N ', N '-dimethylureido) toluene or 1,4-bis (N', N'-dimethylureido) benzene.

Chlortoluron is preferred.

The use of these compounds is described e.g. in the aforementioned U.S. Patent No. 4,283,520. As accelerators, e.g. also those of GB-A 1,192,790 urea derivatives described.

Particularly suitable components (d) were mercaptans with at least two SH groups. The compositions of the invention containing such mercaptans can be pre-solidified under mild conditions (about 20-50 ° C). The pre-prepared compositions thus prepared can be stored for a longer period of time and completely cured without the addition of further curing agents at 65-100 ° C.

I

Suitable mercaptans are e.g. triglycoldimercaptan or 1,2-bis (2'-mercaptoethoxy) ethane called Thiokole® known polymer polysulphides of formula HS (CH ₂ CH ₂ OCH ₂ OCH ₂ CH ₂ SS) _n CH ₂ CH ₂ OCH ₂ OCH ₂ CH ₂ SH, trimethylolpropantritioglycolate and further thioglycolates, such as e.g. US 3,352,810 discloses compounds, aliphatic and cycloaliphatic dithiol types, as described in US 3,716,588,

US 3,734,968, US 3,718,700 and US 3,278,496, poly (mercaptoalkyl) aromatics as described in US 3,310,527, alkylenedithiol or hydroxyalkylenedithiol types as described in US 3,363,026, dipentaerythrithexa (3-mercaptopropionate) or e.g. 2,4,6s-triazintritiol.

Preferred mercaptans are polyoxyalkylenediants, in particular polyoxyalkylenedithiols or trithiols.

This may be the case, for example. polyethylene glycol derivatives, for polypropylene glycol derivatives or also for copolymers with oxyethylene and oxypropylene units. The copolymers may be block polymers or statistical polymers. Suitable block copolymers are also referred to as polypropylene glycolethoxylate or. thereafter polyethylene glycolpropoxylate having terminal polyethylene glycol or polypropylene glycol blocks. Commercially available polypropylene glycols have predominantly secondary terminal hydroxyl groups; it is self-evident that polypropylene dithiols with primary thiol groups can also be used.

Further suitable mercaptans are disclosed in US Patent No. 4,990,697 for polytetrahydrofuranditiols.

Suitable mercaptans also include polyoxyalkylene derivatives such as CapCure® (Henkel Napco AG) such as e.g. CapCure® WR-6 or WR-36, in particular CapCure® 3-800 of the formula

RfO - <- CH ₂ CHC> VCH ₂ CHCH ₂ SH] 3

CH ₃ OH zn = 1-2 and R equal to the trivalent aliphatic hydrocarbon residue.

Particularly suitable mercaptans of compounds of formulas

HS (CH ₂ CH ₂ O) _7T CH ₂ CH ₂ SH and H§ (CH ₂ CH ₂ CH ₂ CH ₂ O) _h? CH ₂ CH ₂ CH ₂ CH ₂ SH zm = 7-8,12-13 or 26-27.

I

Most preferred are triglycoldimercaptan and CapCure® 3-800.

A particularly preferred embodiment of the present invention comprises, as component (d), a mixture of a latent hardener and mercaptan with at least two SH groups.

When heating such a mixture in a DSC apparatus (DSC = Differential Scanning Calorimeter), the DSC diagram (reaction enthalpy as a function of temperature) shows two expressed maxima and a clear separation of the baselines. The first reaction maximum is interpreted by the resin metabolism with mercaptan (B-step) and, depending on the selected composition, e.g. in the range of from about 40 to about 110 ° C. The second maximum comes from the crosslinking with a latent hardener and is e.g. in the range of about 100 to 140 ° C, preferably about 110 to 135 ° C.

Component (d) of the mixture of substances of the invention is generally used in amounts of about 3-60 parts by weight, preferably about 5-50 parts by weight, per 100 parts by weight of the epoxy resin.

When used as component (d), the mixture of latent hardener and mercaptan then the compositions of the invention typically contain about 15-40 parts by weight, preferably 20-35 parts by weight of the latent hardener and about 3-20 parts by weight, preferably 5-15 parts by weight of mercaptan , each with respect to 100 parts by weight of epoxy resin.

The amounts of additional accelerators used in the given case for latent fortification are known to those skilled in the art.

Examples of suitable amounts of individual components of a mixture of a substance of the invention are apparent from the compositions of embodiments.

The compositions of the invention may also be recovered from a solution, e.g. in methylethylketone.

If desired, reactive diluents such as e.g. - monoglycidyl ether of isomeric higher alcohols, such as e.g. Grilonite RV1814® Fa.Ems-Chemie or butylglycidyl ether, 2,2,4 trimethylpentylglycidyl ether, phenylglycidyl ether, cresylglycidyl ether or glycidyl ester.

Mixtures of the substances of the invention may also contain adhesive agents. In principle, any known adhesive may be used. Silanes such as e.g. 7-glieidyloxypropyltrimethoxysilane (Silane A-187 Fa.Union Carbide) or γ-mercaptopropropyltrimethoxysilane (Silan A-189 Fa. Union Carbide) or titanium compounds such as tetraisopropyl-bis (dioctylphosphonato) -titanate (KR 41B Fas. Kenrich Inc. USA.

As further conventional additives, the compositions of the invention may further comprise extension agents, fillers and reinforcing agents, such as e.g. coal tar, bitumen, textile fibers, glass fibers, asbestos fibers, pine fibers, carbon fibers, mineral silicates, mica, quartz flour, aluminum oxide hydrate, bentonite, volastonite, kaolin, aerogelchemical acids or metal powder, e.g. aluminum powder or iron powder, further pigments and dyes, such as carbon black, oxide dyes and titanium dioxide, flame retardants, thixotropic agents, fluids (flcw control agents), such as silicones, waxes and stearates, also partially usable as separating agents , antioxidants and light protectants.

The preparation of the mixture of substances according to the invention can be carried out in the usual way by mixing the components with known agitators (mixers, cylinders).

The compositions of the invention can be used e.g. such as adhesives, adhesive films, hot-melts, pastes, one-component adhesives, labels) matrix resins, varnishes, sealants or grout, or for general use in the preparation of hardened products. They can be used in a formulation that is each adapted to a particular application, in an unfilled or filled state, e.g. such as sealants, lubricants, coating materials, varnishes, displacement resins, fusion resins, and in particular as impregnating resins, resin laminates, matrix resins and adhesives.

The invention therefore also relates to cross-linked products obtained by curing the mixture of substances of the invention. j

Crosslinked systems have excellent mechanical and thermal properties, even if complete curing takes place only after long-term storage (several weeks to months) of the curable mixture.

As mentioned, suitable mixtures of the substances within the meaning of the invention are particularly as impregnating resins for the preparation of fiber composites. The subject of the present invention are therefore also fiber composites impregnated with the mixture of substances of the invention, prepregs obtained by impregnating the tissue with the mixture of substances and optionally subsequent heating of the impregnated tissue, as well as laminates obtained by fully curing the prepregs.

Because the compositions of the invention are curable even at relatively low temperatures of 70100 ° C, they can be used especially with respect to heat-sensitive materials, such as e.g. polyurethane. The preferred area of application is therefore the preparation of skis, boats, other sporting articles and housing components.

Further, mixtures of the substances of the invention can be used as adhesives, in particular Hotmelt reaction adhesives and adhesive films.

The following examples illustrate the invention.

EXAMPLES 1-9

In the compositions defined in Table 1, the following components are used:

Epoxy Resin 1: diglycidyl ether bisphenol A with an epoxy equivalent weight of 186.2 g / eq Epoxy Resin 2: diglycidyl ether bisphenol F with an epoxy equivalent weight of 165.3 g / eq Epoxy Resin 3: diglycidyl ether hexanediol with epoxy equivalent weight of 112 g / eq Latent hardener 1: 4,4'-diaminodiphenylsulfone Latent hardener 2: a mixture of 28 parts by weight of dicyandiamide and 72 parts by weight of diglycidyl ether bisphenol A with an epoxy equivalent weight of 192.3 g / eq CapCure® 3-800: R- -Of-CH ₂ CHO ^ ₂ -CH ₂ CHCH ₂ SH tov. and Henkel Napco AG ch ₃ oh J ₃

The ingredients are prepared by mixing all the ingredients, if necessary with gentle heating.

Isothermal curing at 100 ° C for 15 minutes

The compositions listed in Table 1 are stored under different conditions and subsequently isothermally solidified.

Curing, DSC and T _g measurements are performed with the Mettler Thermoanalytical System TA-3000. In this case, 15-20 mg of the composition in the measuring cell is isothermally solidified at 100 ° C for 15 minutes.

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OT w

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OT ω

Ον o O oo \ O o 00 CM <- < οο o o oo in 25 00 CM Γ O O OO Ό S2 00 CM Ό O O OO Ό £ 2 OO CM «Ο g Ό r— < 3- 00 VO 8 a rH m «N o n- oo oo About cn T— < CM g cn in oo r-H 1-H , 'CJ O * - <CM -C About CM CM C T “H Example no. Epoxy resin 1 Epoxy resin 2 Epoxy resin 3 Latent hardener 1 Latent hardener 2 triethylene glycol dimimercaptan CapCure ^ 3-800 1- Methylimidazole 2- Ethylimidazole 2-dimethylaminoethyl-3-dimethylaminopropyl ether N, N, N ', N', N-pentamethyldiethylenetriamine N, N'-dimethylpiperazine Methyltetrahydrophthalic acid anhydride Methylnadicanhydride Hexahydrophthalic acid anhydride Methylhexahydrophthalic acid anhydride Tetrapropenyl ester anhydride

Then measure the residual enthalpy in the same apparatus at a heating rate of 10 ° C / min.

The metabolism (- crosslinking rate) is calculated by the following equation:

metabolism [%] = total enthalpy - residual enthalpy x 100 total enthalpy

The gelatinization time at 100 ° C is determined on the heating plate after the aunt's automatic time. In doing so, draw a wire arc (φ 0.4 mm) through the substance until a certain strength of the substance is reached.

Table 2 lists the total enthalpy, residual enthalpy and metabolic reactions of the reaction reactions as well as the gelatin times at 100 ° C.

Table .2: .. Metabolism after 15 million hardening at 100 C and gelatinization time at 100 ° C

Example Saves / Enthalpy ^ [J / g] Remaining enthalpy / J / gy Metabolism /% / & with gelatinirap ori. 100 ° C · ', 1 fresh 7d / 5 ° C 424 13.9 • 28.4 96 92 10'33 ” 2 fresh ld / RT ¹ ) 7d / 5 ° C 403 12,0 10.7 24,9 97 98 94 iro4 ” 3 fresh ld / RT 424 94,3 73,0 78,4 83,3 15 * 13 ” 4 fresh ld / RT 403 17.4 16.4 92 93 8 * 16 ” 5 • fresh ld / RT 7d / 5 ° C 427 63,8 45,3 45.5 85 89,4 89,4 1Γ27 ” 6 3d / RT 318,2 98.1 7'27 ” 7 3d / RT 295 98.8 7'24 ” 8 3d / RT 245,5 97.5 8Ί8 ” 9 3d / RT 321,1 96 1Γ22 ”

^ RT: room temperature

Stability prevents at room temperature and at 5 ° C

Glass tissue Fa. Interglas (92146-1-550) (43 x 25 cm) was impregnated on film with a mixture of binders of Examples 1, 2, 4 and 5 at room temperature. Impregnation with the composition of Example 3 was carried out on the basis of a relatively high viscosity at 40 ° C. To remove air and distribute the binder optimally, roll the glass rod over the prepreg.

In this way, the prepared prepregs are stored for longer periods at room temperature and at 5 ° C and tested at various intervals for their stickiness and flexibility. The results are presented in Table 3 with the following levels:

stickiness: with: too sticky i: ideal (desired stickiness) z / i: stickiness between z and i i / t: almost dry t: dry flexibility: with: very flexible f: flexible sp: fragile

Table 3: Stability prevents at room temperature and at 5 ° C

Example 1 Save at RT (days) 1 2 3 4 5 6 Sticky z z i i i / t t Flexibility s s f f f sp Keep at (days) 7 15 30 42 57 Stickiness at RT z z i i t Flexibility pci RT s s f f sp Example 2 ____ L Save at RT (days) 1 2 ' 3 4 Sticky z z / i i t Flexibility i s f f sp Keep at (days) 7 22 28 49 Stickiness at RT z i t Flexibility at RT s f f sp Example 3 Retention at RT (days) 1 2 , 3 4 Sticky z z / i i t Flexibility s f f sp Keeping at 'fc (days; 7 19 30 Stickiness at RT z i t Save at RT s f sp Example 4 Keeping it at. RT (days) 1 2 3 4 5 ' Sticky z i i i / t t Flexibility s f f f sp Preservation at (days 7 22 44 Stickiness at RT z i i 'Flexibility at RT s - f f Example 5 Keeping it at. RT (days) 1 2 3 4 5 6 Sticky z z i i i / t t Flexibility s s f f f sp Maintenance at 5¾ (days '7 15 30 Stickiness at RT z z i / t Flexibility at RT s s SP

Table 3: Continued

Example 6 Save at RT (days) 1 2 3 4 5 6 Sticky z i i i i / t t Flexibility s f f f f sp Example 7 Save at. RT (days) 1 2 3 4 Beautiful jility-_L. z i i t Flexibility s fi f -. sp Example 8 Save at RT (days) 1 2 3 4 5 6 Sticky z z i i i / t t Flexibility s s f f f sp Example 9 _{> {} > Save at RT (days) 1 2 ,, 3 4 5 6 Sticky z z i i i / t t Flexibility s s f f f sp

Properties of hardened products

To determine the tensile strength according to DIN 53283, harden the prepregs for 15 minutes at 100 ° C.

To prepare the laminate, cut the prepregs into equally large sections (6.5 x 9.9 cm). The foil is removed, 12 layers of prepregs are placed on top of one another and in this form are pressed on a press with max. 5 MPa and set for 15 minutes at 100 ° C. The thickness of the laminate is 3-3,3 mm. From the laminate prepared in this way, test specimens were measured to measure the interlaminamic shear strength according to ASTM-D-2344.

The measurement results are listed in Table 4.

Table 4

Example Tensile shear strength / N / mm ² / Interlaminar / N / mm ² /, A 1) shear strength B 1 16.2 66,2 52,4 2 14.6 63,2 53,1 3 17,1 66,3 51.6 4 17,9 5 11.4 72,2 64 6 18.6 7 18,0 8 24,0 9 19.6

in A: measured after hardening

B: measured after curing and after 1 h in boiling water

Curing at 65-80 ° C

The compositions of Examples 1-5 were cured at temperatures between 65 and 80 ° C. Using the DSC (Mettler TA 3000), we determine the glass transition temperatures (T _go : intersection of the extended baseline with a tangent to the measurement curve in the steepest ascent region), as well as the remaining enthalpy, and the metabolites calculated from this are listed in Table 5.

Table 5: T _go , residual enthalpy and metabolism after solidification at 65-80 ° C

Hardening T _g0 [° C] Remaining enthalpy / J / g / Metabolism /% / 4W ^E c ¹ 75 32 91 8 h / 65 ° C 75.5 30 92 6h / 70 ° C 80 20 94 8 h / 70 ° C 80 20 94 2 h / 80 ° C 82 0 100 Example 2 6 h / 65 ° C 73 47 89 8 h / 70 ° C 79 35 92 2 h / 80 ° C 82 0 100 Example 3 24 h / 65 ° C 84 84.6 81 8 h / 70 ° C 92 86.5 8 h / 80 ° C 97 92 Example 4 24 h / 65 ° C 81 36 < 84 8h / 7 ° C 85.5 25 89 8 h / 80 ° C 89 21 91 Example 5 4 h / 80 ° C 108 0 100

Claims (21)

PATENT APPLICATIONS Claims 1. A curable composition comprising (a) an epoxy resin, (b) a tertiary amine or imidazole compound, and (c) up to 30% by weight of polycarboxylic acid anhydride by weight of component (a). Composition according to claim 1, characterized in that it contains 1-20% by weight, preferably 2-15% by weight of component (c) by proportion of component (a). Composition according to claim 1, characterized in that the epoxy resin (a) is liquid. Composition according to claim 1, characterized in that the epoxy resin (a) is diglycidyl ether biphenol or epoxide novolak. Composition according to claim 1, characterized in that the epoxy resin (a) is diglycidyl ether bisphenol A or bisphenol F. Composition according to claim 1, characterized in that it contains tertiary amine (b) of two or more nitrogen atoms. Composition according to claim 1, characterized in that it contains tertiary amine (b) of two or three dialkylamino groups. Composition according to claim 1, characterized in that the tertiary amine (b) 2-dimethylaminoethyl-3-dimethylaminopropyl ether, Ν, Ν′-dimethylpiperazine, or Ν, Ν, Ν ', Ν', Ν '' - pentamethyldiethylenetriamine. Composition according to claim 1, characterized in that component (b) is an imidazole compound. Composition according to claim 1, characterized in that component (b) is 1-methylimidazole or 2-ethylimidazole. Composition according to claim 1, characterized in that the polycarboxylic acid anhydride (c) is dicarboxylic acid anhydride. Composition according to claim 1, characterized in that the polycarboxylic acid anhydride is selected from the group consisting of phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl anhydride anhydride methyl anhydride anhydride methyl anhydride anhydride Composition according to claim 1, characterized in that in addition to components (a) to (c), it contains (d) one or more epoxy resin hardeners. A composition according to claim 1, characterized in that component (d) is a latent curing agent. 15. The composition of claim 14, wherein the latent curing agent is 4,4'diaminodiphenylsulfone or dicyandiamide. 16. The composition of claim 13, wherein component (d) is mercaptan with at least two SH groups. Composition according to claim 13, characterized in that component (d) is a mixture of a latent hardener and mercaptan with at least two SH groups. Crosslinked products, characterized in that they are obtained by curing the composition according to claim 1. 19. Fiber composite, impregnated with a mixture of substances according to claim 1. Carpets, characterized in that they are obtained by impregnating tissue with the composition of claim 1. 21. Laminates, characterized in that they are obtained by fully curing the prepregs according to claim 20. 22065-VI-92 / LZ For CIBA-GEIGY AG: NA SUMMARY Curable epoxy resin composition containing blocked accelerator Curable compositions comprising (a) an epoxy resin, (b) a tertiary amine or imidazole compound, and (c) up to 30% by weight of polycarboxylic acid anhydride relative to the proportion of component (a) are suitable for the preparation of flexible prepregs with high storage stability. The prepregs can be cured at relatively low temperatures of 65-100 ° C.