Patent Description:
In the state of the art (e.g., <CIT>), it is taught that the mole ratio of the polyepoxide resin and the polyisocyanate can play a role in the dimensional heat stability and on the mechanical properties. For instance, the mole ratio can be below <NUM>, and the reaction-resin mixture is crosslinked in the presence of a hardening catalyst in the temperature range between <NUM> and <NUM> and then post-hardened at temperatures of up to <NUM>. The obtained product shows good dimensional heat stability. However, it has insufficient mechanical properties and inappropriate temperature cycle resistance. This can be solved by having said molar ratio above <NUM> or by adding flexibilising or elastifying agent in the reaction mixture. The viscosity is often difficult to manage.

Conventionally, the polyepoxide resin of a known two-component-reaction-resin mixture is mainly based on aromatic reactive epoxy resins, such as DGEBA (diglycidyl ether of bisphenol A). The final product is limited by its mechanical properties, in particular in terms of tensile elongation at break and tensile maximum strength.

The two-component-heat-curable-reaction-resin mixture can be used in encapsulated rotors, as described in <CIT>, which discloses products, which present cracks, under certain conditions.

There is therefore a need to provide an improved two-component-heat-curable-reaction-resin mixture suitable for impregnation or encapsulation material for coils, stators, rotors in electric engine, by ensuring appropriate mechanical properties, in particular in terms of tensile elongation at break and tensile maximum strength. Such system / reaction mixture should also be (thermo)mechanically efficient, when used in a filled system and / or in the presence of a toughener (without the formation of cracks).

<CIT> discloses a heat-curable composition comprising a polyisocyanate, a triglycidyl ether of trimethylolpropane and a solution of Lithium Chloride (LiCl) being used as a trimerization catalyst composition. LiCl used as a cure accelerator leads to start the cure of the resin composition immediately and then, said composition cannot be homogenized, degassed, and applied as required for the impregnation and encapsulation processes.

However, the impregnation and encapsulation processes require that the resins don't start to cure at moderate temperature (up to <NUM>). In other words, before the curing step implemented in the impregnation and encapsulation processes, the mixture of all the components of the resin needs a certain latency at moderate temperatures (up to <NUM>) in order to allow the composition to be homogenized, degassed, and applied. Therefore, the latency of the resin composition at moderate temperature allowing said composition to be homogenized, degassed, and applied is a requirement to be met.

It is an object of the present invention to overcome the aforementioned drawbacks by providing a heat-curable-reaction-resin mixture (referred in the application as '<NUM> resin system') suitable for impregnation or encapsulation material for coils, stators, rotors in electric engine, which reaction-resin mixture comprises:.

Using a (cyclo)aliphatic epoxy resin composition as recited above enables improving the <NUM> resin system by increasing the tensile properties (tensile maximum strength and tensile elongation at break), and, when filled, also the toughness (K1c and G1c) of the cured <NUM> resin system. This leads to a higher crack resistance, which is increasingly demanded by the e-vehicle market, in order to produce crack-resistant rotors for e-motors. The (cyclo)aliphatic epoxy resin composition as recited above is also suitable for the impregnation and encapsulation processes because the latency of the epoxy composition at moderate temperature avoids the start of the cure of said composition during the homogenization, degassing and applying steps. The term "latency" according to the invention refers to the viscosity of the epoxy composition. The term "moderate latency" according to the invention refers to the viscosity of the epoxy composition measured after the steps of homogenization and degassing. The viscosity of the epoxy composition measured after the steps of homogenization and degassing is compared to the viscosity of the epoxy composition measured just after mixing all the components of said composition together, also called the initial viscosity of the epoxy composition viscosity. According to the invention, the epoxy composition is qualified of having a moderate latency when its viscosity measured after the steps of homogenization and degassing is less than twice the initial viscosity of the epoxy composition. The viscosity of the epoxy composition is measured on a Brookfield CAP2000+ viscometer according to ISO <NUM>. According to a preferred embodiment, said epoxy resin composition (predominantly) comprises butanediol diglycidyl ether, hexanediol diglycidyl ether, <NUM>,<NUM>-cyclohexane dimethanol diglycidyl ether, hexahydrophthalic acid diglycidyl ester, trimethylolpropane triglycidyl ether, pentaerythritol polyglycidyl ether, neopentyl glycol diglycidyl ether, or mixtures thereof.

According to an advantageous embodiment of the invention, the equivalent ratio of isocyanate groups of component (a) - polyfunctional isocyanate - to epoxide groups of component (b) - epoxy resin - is from <NUM>:<NUM> to <NUM>:<NUM>, preferably from <NUM>:<NUM> to <NUM>:<NUM>. This enables to increase the (thermo)mechanical effects provided by the <NUM> resin system of the present invention.

Furthermore, the polyfunctional isocyanate is preferably selected from the group comprising alicyclic polyisocyanates, aromatic polyisocyanates and mixtures thereof. The selection of the polyfunctional isocyanate in combination with the selected epoxy resin composition of the invention enables further increasing the (thermo)mechanical properties of the <NUM> resin system.

In a particularly preferred embodiment of the invention, the polyfunctional isocyanate is selected from the group comprising diphenylmethane-<NUM>,<NUM>- or -<NUM>,<NUM>'-diisocyanate; polyphenylene polymethylene polyisocyanate; diphenylmethane diisocyanates containing a carbodiimide group or uretonimide group; modified polyisocyanates containing an allophanate group, urethane group, biuret group and/or urethidione group; isocyanate based prepolymers obtained by reaction of an excess of the above mentioned polyisocyanates with polyols; and mixtures thereof.

The cure accelerator is based on boron trichloride-amine complex, being preferably selected from the group comprising boron trichloride-dimethyloctylamine complex, boron trichloride-trimethylamine complex, boron trichloride-benzyldimethylamine complex, boron trichloride-tributylamine complex, and mixtures thereof. Said cure accelerator based on boron trichloride-amine complex allows the composition to have a latency at moderate temperature during the homogenization, degassing and applying steps.

According to a preferred embodiment, the cure accelerator is present in an amount between <NUM> and <NUM> wt%, preferably between <NUM> to <NUM> wt%, based on the total weight of said mixture.

The reaction-resin mixture according to the invention is preferably anhydride free.

Other embodiments of the reaction resin mixture of the present invention are mentioned in the annexed claims.

The invention also concerns a heat cured composition obtained by curing the reaction-resin mixture according to the invention and as above-described. Said heat cured composition has a tensile elongation at break of at least <NUM> % measured according to ISO <NUM> and a tensile maximum strength of at least <NUM> MPa measured according to ISO <NUM>.

In a preferred embodiment, the heat cured composition is obtained by mixing the components of the mixture according to the present invention, and curing the obtained composition leading to the heat cured composition of the invention. This embodiment corresponds to the cured <NUM> resin system, obtained by cross-linking under heat. The terms "heat cured composition" and "Cured <NUM> resin system" have the same meaning and can be used interchangeably.

Other embodiments of the heat cured composition of the present invention are mentioned in the annexed claims.

The present invention further relates to a process for providing a composite or a casted article comprising the following steps:.

In a preferred embodiment, the process according to the invention further comprises the following steps :.

In a particularly advantageous embodiment of the invention, the fibers are selected from the group comprising glass or carbon fibers.

In a preferred embodiment, said electrical components are selected from the group comprising coils, motors, stators, rotors, generator parts, printed circuit boards, car ignition coils.

Preferably, said impregnated fibers form a composite article by using infusion process, wet compression moulding process, filament winding process and / or pultrusion process.

In an additional preferred embodiment, said electrical components are impregnated with said mixture by dipping, trickle impregnation, vacuum pressure impregnation and / or casting.

Other embodiments of the process of the present invention are mentioned in the annexed claims.

The invention also relates to an article obtained by applying the following steps: mixing the components of the reaction-resin mixture according to the invention, adding at least one mineral filler or metal powder to said mixture, and curing the obtained composition, in order to provide the article, wherein the mineral filler is preferably selected from the group comprising silica, fused silica, fumed silica, alumina, wollastonite, aluminium trihydroxide, magnesium hydroxide, AlO(OH), silicium carbide, boron nitride, calcium carbonate, aluminosilicates, glass powder, and mixtures thereof.

Preferably, said filler is a silane treated filler, preferably a silane treated amorphous silica.

More preferably, the article of the present invention has a tensile maximum strength of at least <NUM> MPa measured according to ISO <NUM> and a plane strain fracture toughness (K1c) of at least <NUM> MPa. m<NUM>/<NUM>, wherein before cure, at least one toughener is added to said mixture, wherein said toughener is selected from the list comprising core shell rubber, polyacrylate, carboxyl-terminated butadiene acrylonitrile (CTBN) rubber, styrene-butadiene rubber (SBR), phenoxy toughener, silicon block copolymer toughener.

This embodiment is particularly advantageous in terms of toughness (K1c and G1c) of the cured <NUM> resin system, when filled with the above compound(s). This leads to a higher crack resistance, which is increasingly demanded by the e-vehicle market, in order to produce crack-resistant rotors for e-motors.

Other embodiments of the article of the present invention are mentioned in the annexed claims.

The invention also covers encapsulation material for electrical components, such as coils, stators and rotors, which comprises the composition according to the present invention or the article as defined in the present invention.

The present invention provides a <NUM> resin system exhibiting unique thermomechanical properties, in particular when they are filled with mineral fillers and toughened with, for instance a core-shell rubber toughener, compared to similar state-of the-art-resin systems.

The invention is related to a two-component resin system based on polyfunctional isocyanates (for instance, MDI based resins, wherein the polyfunctional isocyanate can be Suprasec <NUM> or Suprasec <NUM>) and epoxy resin composition being preferably aliphatic reactive epoxy-diluents, such as butanediol diglycidyl ether (Araldite DY-D) or hexanediol diglycidyl ether (Araldite DY-H). Additionally, at least one cure accelerator is used, for instance a boron trihalide-amine complex (boron trichloride-dimethyloctylamine complex - Accelerator DY <NUM> or boron trichloride-trimethylamine).

When the polyfunctional isocyanate is mixed with the epoxy resin, a temperature ranging between <NUM> and <NUM> can preferentially be applied. This is also applicable with the filled system. In this step, it advisable to avoid any pre-reaction between the polyfunctional isocyanate and the epoxy resin.

Regarding the hardening of the reaction resin mixture - reaction between said polyfunctional isocyanate and said epoxy resin should occur here, this process step can advantageously take place at a gelling temperature between <NUM> and <NUM>, preferably between <NUM> and <NUM> and the post-hardening at a temperature between <NUM> - <NUM>, preferably between <NUM> and <NUM>.

Regarding the hardening of the filled <NUM> system, this process step can take place at a gelling temperature between <NUM> and <NUM>, preferably between <NUM> and <NUM> and the post-hardening at a temperature between <NUM> - <NUM>, preferably between <NUM> and <NUM>.

By replacing the aromatic epoxy resin with an aliphatic epoxy resin the tensile properties (strength and elongation) and the toughness (K1c and G1c) of the cured resin are significantly increased.

The filled <NUM> resin system of the invention is preferably used in rotors, stators, coils in electric engine.

The <NUM> resin system can be used in any product involving Impregnation / encapsulation processes.

In a particularly preferred embodiment of the invention, the material produced with the <NUM> resin system will have a lattice structure of isocyanurate, in which the mole ratio of oxazolidinone rings to the isocyanurate rings is between <NUM> and <NUM>.

Below examples illustrate the objects of the present invention without being limited.

Example <NUM> is obtained by applying the following steps: <NUM> Suprasec <NUM>, <NUM> Araldite DY-H and <NUM> Accelerator DY <NUM> are homogenized and degassed at <NUM> for <NUM> under stirring. Afterwards, the mixture is poured into a hot aluminum mold, preheated to <NUM>, to prepare specimens of <NUM>- and <NUM>-mm thickness for tensile testing, bend-notch testing and Dynamic Mechanical Analysis (DMA). The composition is cured in an oven at <NUM> for <NUM> and at <NUM> for another <NUM>.

Example <NUM> corresponds to the steps referred for example <NUM>, except that Araldite DY-H is replaced by a molar equivalent amount of Araldite DY-D.

Example <NUM> correspond to example <NUM>, except that Suprasec <NUM> is replaced by a molar equivalent amount of Suprasec <NUM>.

Examples <NUM> corresponds to example <NUM>, except that Suprasec <NUM> is replaced by a molar equivalent amount of Suprasec <NUM>.

Example <NUM> corresponds to example <NUM>, except that <NUM> phr Araldite DY-H is used instead of <NUM> phr.

The effect of different aliphatic reactive epoxy-diluents in combination with MDI based polyfunctional isocyanates (Suprasec <NUM>, Suprasec <NUM>) and the curing catalyst boron trichloride-dimethyloctylamine complex (Accelerator DY <NUM>) on the mechanical properties are illustrated in table <NUM> below.

It was found that the replacement of the aromatic epoxy resin Araldite GY <NUM> with the aliphatic epoxy resins Araldite DY-D or Araldite DY-H leads to a significant increase in tensile elongation, tensile strength and toughness (G1c, K1c) without any detrimental impact on glass transition temperature.

The same effect can be observed when Suprasec <NUM> is used instead of Suprasec <NUM> and the stoichiometric ratio of isocyanate equivalent to epoxy equivalent is changed from <NUM>/<NUM> to <NUM>/<NUM>.

Comparative example <NUM> is obtained by applying the following steps: <NUM> Suprasec <NUM>, <NUM> Araldite GY250 and <NUM> Accelerator DY <NUM> are homogenized and degassed at <NUM> for <NUM> under stirring. Afterwards the mixture is poured into a hot aluminum mold, preheated to <NUM>, to prepare specimens of <NUM>- and <NUM>-mm thickness for tensile testing, bend-notch testing and Dynamic Mechanical Analysis (DMA). The composition is cured in an oven at <NUM> for <NUM> and at <NUM> for another <NUM>.

Comparative example <NUM> is performed by applying referred in comparative example <NUM> above, except that Suprasec <NUM> is replaced by a molar equivalent amount of Suprasec <NUM>.

Comparative example <NUM> corresponds to comparative example <NUM>, except that <NUM> phr Araldite GY250 is used instead of <NUM> phr.

Example <NUM> is obtained by applying the following steps: <NUM> Suprasec <NUM>, <NUM> Araldite DY-H and <NUM> Accelerator DY <NUM> are homogenized and degassed at <NUM> for <NUM> under stirring. Then, <NUM> silica flour and <NUM> wollastonite are added in portions under stirring within <NUM> minutes. The mixture is carefully degassed at <NUM> for <NUM>. Afterwards the mixture is poured into a hot vacuum press, preheated to <NUM>, to prepare specimens of <NUM> thickness for tensile testing, double torsion testing and DSC. The composition is pre-cured inside the vacuum press at <NUM> for <NUM>. After demolding the composite plate is post-cured in an oven at <NUM> for another <NUM>.

Example <NUM> corresponds to example <NUM>, except that Araldite DY-H is replaced by a predispersion of <NUM> phr PARALOID in <NUM> phr Araldite DY-H.

Example <NUM> corresponds to example <NUM>, except that Araldite DY-H is replaced by a predispersion of <NUM> phr PARALOID in <NUM> phr Araldite DY-D. The combined amount of silica flour and wollastonite is replaced by a weight equivalent amount of fused silica flour.

In a second embodiment of the invention, it could be shown that above described resin systems (e.g. example <NUM>), when filled with mineral fillers, exhibit unique thermomechanical properties, compared to similar state of the art resin systems and show even more advanced properties, when additionally toughened with for instance a core-shell rubber toughener (table <NUM>).

The cured non-toughened resin filled with mineral filler exhibits a unique high toughness (K1c, G1c) in combination with a very high Tg ><NUM> (ex. The K1c exceeds or is at least on the same level than filled state of the art resins (comp. <NUM>-<NUM>) but with the big difference that the latter can achieve such high values only by incorporation of a significant amount of toughener.

When additionally, a toughener is incorporated into the neat resin matrix of the invention the toughness increases to outstanding high values of K1c = <NUM>-<NUM> MPa. m<NUM>/<NUM> (ex. <NUM>-<NUM>). Furthermore, the tensile maximum strength is increasing up to <NUM> MPa and tensile elongation at break up to <NUM> %, which is highly advantageous.

Comparative example <NUM> of table <NUM> below corresponds to composition A1 disclosed in <CIT> which relates to a resin type of cycloaliphatic epoxy / homopolymerization catalyst.

Comparative examples <NUM> relates to resin type of cycloaliphatic epoxy / methyl nadic anhydride and was obtained as follows:
Component A of comparative example <NUM> (i.e., the resin part) was prepared as following:
In a 2I ESCO mixer with exterior heating and speed disc for stirring following components were added: <NUM> Celloxide <NUM> P, <NUM> RPS <NUM>-<NUM>, <NUM> Antischaum SH, <NUM> Silan A-<NUM> at room temperature to vessel. All components were heated up to <NUM> while stirring for <NUM> at <NUM> rpm under a vacuum of <NUM> mbar. Then <NUM> Genioperl® P52, <NUM> amorphous silica <NUM>, <NUM> amorphous silica <NUM>, <NUM> Wollastonite <NUM> and <NUM> Bentone SD-<NUM>, were added to the mixing vessel under stirring in portions (temperature decreased to <NUM> - <NUM>). The mixture was stirred (<NUM> rpm) at <NUM> at <NUM> mbar for <NUM>. Then <NUM> BYK W-<NUM> were added to the mixture. The mixture was stirred again for <NUM> at <NUM> rpm at <NUM> mbar. Finally, the mixture (component A) was cooled down to <NUM> and discharged into a container.

The component B of comparative example <NUM> (i.e., the hardener part) was prepared as follows:
In a <NUM> liter ESCO mixer with exterior heating and speed disc for stirring, <NUM> ARADUR® HY <NUM> was added. Then the vessel was heated up to <NUM> - <NUM>. <NUM> Genioperl® W <NUM> were then added. At <NUM> - <NUM> the mixture was stirred under vacuum (<NUM>-<NUM> mbar) until the Genioperl® W <NUM> was totally dissolved in the ARADUR® HY <NUM> (very slightly opaque liquid). Afterwards it was cooled to <NUM> - <NUM> and <NUM> Oracet blue <NUM> was added. Then the mixture was stirred until a homogenous blue liquid was visible. Then <NUM> DY <NUM>, <NUM> BYK W <NUM>, <NUM> BYK W <NUM> and <NUM> PEG <NUM> were added at <NUM> - <NUM> into the vessel. Then the mixture was stirred with <NUM> rpm under vacuum (<NUM> mbar) for <NUM> at <NUM>. Then <NUM> Amorphous silica <NUM>, <NUM> Wollastonite <NUM> and <NUM> Bentone SD-<NUM> were added in portions to the liquid while stirring and increasing the stirrer speed to <NUM> rpm under vacuum (<NUM> mbar). The temperature should rise within <NUM> to <NUM> - <NUM> due to the stirring. The mixture was kept under stirring for <NUM> at <NUM> rpm and vacuum (<NUM> mbar) without heating (temperature in the vessel was <NUM> - <NUM>). Then <NUM> Aerosil R-<NUM> was added to the mixture and stirred in at <NUM> rpm for <NUM> at <NUM> - <NUM>. Then the speed was increased to <NUM> rpm for another <NUM>. Finally, the mixture was cooled to <NUM> - <NUM> and discharged into a container.

<NUM> of the resin formulation (component A) and <NUM> of the hardener formulation (component B) were put together and heated to about <NUM> while stirring with <NUM> rpm under vacuum. To produce <NUM> thick test plates, metal moulds were preheated to about <NUM> in an oven. Then the degassed resin/hardener mixture was poured into the mould. The mould was then put to an oven at <NUM> for <NUM> minutes, then heated up to <NUM> and kept at <NUM> for <NUM> hours. Then the mould was taken out of the oven and opened after cooling down to room temperature. The cured plate was subjected to various tests the results of which are given in table <NUM>.

Comparative example <NUM> relates to cycloaliphatic epoxy / methyl tetrahydrophthalic anhydride and is obtained as follows:
Same steps as discloses for comparative example <NUM>, regarding component A. Regarding component B of this comparative example <NUM>, it was prepared as following:
In a <NUM> liter ESCO mixer with exterior heating and speed disc for stirring, <NUM> ARADURE® HY <NUM>-<NUM> was added. Then it was heated up to <NUM> - <NUM>. <NUM> Genioperl® W <NUM> was then added. At <NUM> - <NUM> the mixture was stirred under vacuum (<NUM>-<NUM> mbar) until the Genioperl® W <NUM> was totally dissolved in the ARADURE® HY <NUM>-<NUM>. Afterwards it was cooled to <NUM> - <NUM> and <NUM> Oracet blue <NUM>, <NUM> DY <NUM>, <NUM> BYK W <NUM>, <NUM> BYK W <NUM> were added at <NUM> - <NUM> into the vessel. Then the mixture was stirred with <NUM> rpm under vacuum (<NUM> mbar) for <NUM> at <NUM>. Then <NUM> Amorphous silica <NUM>, <NUM> Wollastonite <NUM> and <NUM> Bentone SD-<NUM> were added in portions to the liquid while stirring and increasing the stirrer speed to <NUM> rpm under vacuum (<NUM> mbar). The temperature should rise within <NUM>. to <NUM> - <NUM> due to the stirring. The mixture was kept under stirring for <NUM> at <NUM> rpm and vacuum (<NUM> mbar) without heating (temperature in the vessel <NUM> - <NUM>). Then <NUM> Aerosil R-<NUM> was added to the mixture and stirred in at <NUM> rpm for <NUM> at <NUM> - <NUM>. Then the speed was increased to <NUM> rpm for another <NUM>. Finally, the mixture was cooled to <NUM> - <NUM> and discharged into a container.

<NUM> of the resin formulation (component A) and <NUM> of the hardener formulation (component B) were put together and heated to about <NUM> while stirring with <NUM> rpm under vacuum. To produce <NUM> thick test plates, metal moulds were preheated to about <NUM> in an oven. Then the degassed resin/hardener mixture was poured into the mould. The mould was then put to an oven at <NUM> for <NUM> minutes, then heated up to <NUM> and kept at <NUM> for <NUM> hours. Then the mould was taken out of the oven and opened after cooling down to room temperature. The cured plate was subjected to various tests the results of which are given in table <NUM>.

Example <NUM> corresponds to Example <NUM> and is obtained by applying the following steps: <NUM> Suprasec <NUM>, <NUM> Araldite DY-H and <NUM> Accelerator DY <NUM> are homogenized and degassed at <NUM> for <NUM> under stirring. Afterwards, the mixture is poured into a hot aluminum mold, preheated to <NUM>, to prepare specimens of <NUM>- and <NUM>-mm thickness for tensile testing, bend-notch testing and Dynamic Mechanical Analysis (DMA). The composition is cured in an oven at <NUM> for <NUM> and at <NUM> for another <NUM>.

Comparative example <NUM> corresponds to Example <NUM>, except that a solution of <NUM> wt% LiCl in <NUM>-methyl-<NUM>,<NUM>-propanediol is used instead of Accelerator DY <NUM>. Comparative example <NUM> is obtained by applying the following steps: <NUM> Suprasec <NUM>, <NUM> Araldite DY-H and <NUM> of a solution of <NUM> wt% LiCl in <NUM>-methyl-<NUM>,<NUM>-propanediol are homogenized and degassed at <NUM> for <NUM> under stirring. However, after <NUM> at <NUM>, the composition comprising Suprasec <NUM>, <NUM> Araldite DY-H and <NUM> of a solution of <NUM> wt% LiCl in <NUM>-methyl-<NUM>,<NUM>-propanediol already start to cure by forming a gel.

The initial viscosities (V0), the viscosities measured after <NUM> minutes at <NUM> (V1) and the viscosities measured after <NUM> hour at <NUM> (V2) of example <NUM> and comparative example <NUM> are given in Table <NUM>.

By way of example, "an isocyanate group" means one isocyanate group or more than one isocyanate group.

The terms "comprising", "comprises" and "comprised of" as used herein are synonymous with "including", "includes" or "containing", "contains", and are inclusive or openended and do not exclude additional, non-recited members, elements or method steps. This means that, preferably, the aforementioned terms, such as "comprising", "comprises", "comprised of", "containing", "contains", "contained of", can be replaced by "consisting", "consisting of", "consists".

Throughout this application, the term "about" is used to indicate that a value includes the standard deviation of error for the device or method being employed to determine the value.

As used herein, the terms "% by weight", "wt%", "weight percentage", or "percentage by weight" are used interchangeably.

Claim 1:
A heat-curable-reaction-resin mixture suitable for impregnation or encapsulation material for coils, stators, rotors in electric engine, which reaction-resin mixture comprises:
a) A polyfunctional isocyanate,
b) An epoxy resin composition predominantly comprising a compound A based on glycidyl ether of aliphatic and / or cycloaliphatic alcohols having at least <NUM> alcohol functionalities, or a compound B based on glycidyl ester of aliphatic and / or cycloaliphatic carbonic acids having at least <NUM> carboxylic acid functionalities,
c) A cure accelerator, wherein the cure accelerator is based on boron trichloride-amine complex.