Epoxy-terminated isocyanate prepolymer and preparation method thereof

Abstract

The invention relates to a process for the preparation of epoxy-terminated impact modifiers, in which one or more polyisocyanates (a) are mixed with two or more polyols (b) comprising at least one polyether polyol (b1) and at least one hydroxyl-terminated rubber (b2), the molar ratio of isocyanate groups to hydroxyl groups being from 10: 1 to 1.5: 1, in the presence of an ionic liquid, the isocyanate-terminated prepolymer is reacted with a polyepoxide (c) to generate an epoxy-terminated impact modifier, in the presence of an ionic liquid, to generate an isocyanate-terminated prepolymer, and in the presence of an ionic liquid, the isocyanate-terminated prepolymer is reacted with the polyepoxide (c) to generate an epoxy-terminated impact modifier. The invention also relates to an epoxy-terminated impact modifier which can be obtained by the method according to the invention, to the use of the epoxy-terminated impact modifier in one-component or two-component epoxy resin compositions, preferably in one-component or two-component epoxy resin adhesives, in order to increase the impact strength of the cured epoxy resin matrix, and to the use of the epoxy-terminated impact modifier in the one-component or two-component epoxy resin compositions, preferably in the one-component or two-component epoxy resin adhesives. The invention further relates to a one-component or two-component epoxy resin composition comprising at least one epoxy-terminated impact modifier according to the invention.

Description

[0001] manual

[0002] The present invention relates to a method for preparing an epoxy-terminated impact modifier, in which one or more polyisocyanates (a) are mixed with two or more polyols (b), which contain at least one polyether polyol (b1) and at least one hydroxyl-terminated rubber (b2), and the molar ratio of isocyanate groups to hydroxyl groups is 10:1 to 1.5:1, to form an isocyanate-terminated prepolymer, and the isocyanate-terminated prepolymer is reacted with a polyepoxide (c) in the presence of an ionic liquid to form an epoxy-terminated impact modifier. The present invention also relates to an epoxy-terminated impact modifier obtainable by the method according to the present invention, to the use of the epoxy-terminated impact modifier in a one-component or two-component epoxy resin composition, preferably in a one-component or two-component epoxy resin adhesive, to increase the impact strength of a cured epoxy resin matrix, and also to a one-component or two-component epoxy resin composition comprising at least one epoxy-terminated impact modifier according to the present invention.

[0003] In the production of motor vehicles and additional parts and / or machines and plants, high-quality adhesives are increasingly used as an alternative to or in combination with conventional joining methods such as screwing, riveting, stamping or welding. This results in advantages and new possibilities in production, such as the production of composite and hybrid materials, or greater freedom in component design. When used in motor vehicle production, adhesives must have good adhesion to all substrates used, in particular electrogalvanized, hot-dip galvanized and phosphated steel sheets, oiled steel sheets and various aluminum alloys that may have undergone surface treatment. These good adhesion properties must be maintained without any significant loss of quality, especially after aging (alternating climates, salt spray baths, etc.). If adhesives are used as body-in-white adhesives in automobile construction, their resistance to cleaning baths and dip coatings (the so-called scrub resistance) is very important so that manufacturers can guarantee process reliability.

[0004] Adhesives for body-in-white should be cured under normal baking conditions, ideally at 180°C for 30 minutes, if they are one-component adhesives. In the case of two-component adhesives, curing should take place at room temperature over a period of days to about a week, but accelerated curing methods should also be possible, such as curing at room temperature for 4 hours followed by curing at 60°C or 85°C for 30 minutes. In addition, they should withstand temperatures of up to about 220°C. A further requirement for such cured adhesives or bonding agents is that they are safe to operate at high temperatures of up to about 90°C and low temperatures of down to about -40°C. Since these adhesives are structural adhesives, they are intended to bond structural components, and high strength of the adhesives (such as high peel strength and high tensile shear strength), reduced crack propagation and high impact strength are essential.

[0005] Conventional epoxy adhesives are characterized by high mechanical strength, especially high tensile strength. However, when the adhesive is subjected to impact stress, conventional epoxy adhesives are often too brittle and therefore fall far short of meeting the requirements under crash conditions where high tensile and peel stresses occur, especially in the automotive industry. In this regard, the strength is often insufficient, especially at high temperatures, and especially at low temperatures (e.g. below 20°C or below 10°C).

[0006] Two methods are known in the literature to reduce the brittleness of epoxy adhesives and thus to improve their impact strength: On the one hand, this can be achieved by adding at least partially crosslinked polymer compounds such as latexes of core / shell polymers or other flexible polymers and copolymers. This method is described, for example, in US 5290857. On the other hand, toughness can also be increased to a certain extent by introducing soft segments, for example by correspondingly modifying the epoxy component. For example, epoxy resin compositions softened by reaction with carboxylic acids (especially dibasic or tribasic fatty acids) and carboxylic acid-terminated diols are described in US 4952645.

[0007] EP 0353190 relates to an epoxy resin softening component based on monophenol or epoxy-terminated polymers. EP 1574537 A1 and EP 1602702 A1 describe epoxy resin adhesive compositions containing monophenol or epoxy-terminated polymers as impact modifiers.

[0008] EP 2060592 describes thermosetting epoxy resin compositions, wherein in one example a toughness improver is prepared from a mixture of polyalkylene glycol and hydroxy-terminated polybutadiene and isophorone diisocyanate and vandanol as blocking agent.

[0009] EP 0383505 relates to a reactive hot melt adhesive comprising a polyurethane prepolymer composed of polyisocyanate and polyether polyol and a thermoplastic elastomer, wherein the polyurethane prepolymer can also be prepared using hydroxyl-terminated polybutadiene.

[0010] EP 1741734 relates to a thermosetting epoxy resin composition comprising an epoxy solid resin and an impact modifier obtainable by reaction of a monohydroxy epoxy compound and an isocyanate-terminated polyurethane polymer, wherein in one example a mixture of a polyalkylene glycol and a hydroxy-terminated polybutadiene as a polyol is used to prepare the polyurethane polymer.

[0011] WO2014 / 072515 relates to an epoxy-terminated impact modifier obtained by preparing a polyurethane prepolymer containing an isocyanate group and reacting the prepolymer with an epoxy resin containing an epoxy compound containing a primary or secondary hydroxyl group. In this case, isophorone diisocyanate is used as the isocyanate component for preparing the polyurethane prepolymer, and a polyol mixture comprising at least one polyether polyol and at least one hydroxyl-terminated rubber is used as the polyol component.

[0012] The disadvantage of polyurethane-bound impact modifiers is poor temperature stability. In addition, the impact modifiers according to the invention are more compatible with epoxy resin matrices, resulting in better impact strength properties.

[0013] In US 5480958, isocyanate-terminated prepolymers are described to react with epoxides to form oxazolidinone structural elements. In this case, potassium acetate is used as a catalyst for the reaction. However, the performance of these impact modifiers still needs to be improved, especially in terms of impact strength, fracture toughness and fracture energy G. 1c aspect.

[0014] It is therefore an object of the present invention to provide an improved impact modifier which provides excellent impact strength, high tensile shear strength, peel strength and reduced crack growth in epoxy resins such as epoxy adhesives. In addition, such an impact modifier should minimize the glass transition temperature of the epoxy resin and should not excessively increase the viscosity of the epoxy resin formulation to ensure ease of processing.

[0015] The object of the present invention is achieved by an epoxy-terminated impact modifier, which can be prepared by the following method: one or more polyisocyanates (a) are mixed with two or more polyols (b), these polyols contain at least one polyether polyol (b1) and at least one hydroxyl-terminated rubber (b2), and the molar ratio of isocyanate groups to hydroxyl groups is 10:1 to 1.5:1, react to form an isocyanate-terminated prepolymer, and react the isocyanate-terminated prepolymer with a polyepoxide (c) in the presence of an ionic liquid to form the epoxy-terminated impact modifier. The present invention also relates to such a method, to the use of the epoxy-terminated impact modifier in a one-component or two-component epoxy resin composition, preferably in a one-component or two-component epoxy resin adhesive, to increase the impact strength of a cured epoxy resin matrix, and also to a one-component or two-component epoxy resin composition, which comprises at least one epoxy-terminated impact modifier according to the present invention.

[0016] To prepare the epoxy-terminated impact modifier according to the invention, in a first step an isocyanate prepolymer is obtained from one or more polyisocyanates (a) and two or more polyols (b).

[0017] All known polyisocyanates for preparing polyurethanes can be used as isocyanate (a). These isocyanates include aliphatic, cycloaliphatic and aromatic divalent or polyvalent isocyanates known in the prior art, and mixtures thereof in any proportion. For example, 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate, mixtures of diphenylmethane diisocyanate monomers and diphenylmethane diisocyanate high-nuclear homologues (polymer MDI), isophorone diisocyanate (IPDI) or oligomers thereof, 2,4- or 2,6-toluene diisocyanate (TDI) or mixtures thereof, tetramethylene diisocyanate or oligomers thereof, hexamethylene diisocyanate (HDI) or oligomers thereof, naphthalene diisocyanate (NDI) or mixtures thereof. Modified isocyanates such as isocyanurates, uretdiones, isoureates or ureaimine-modified polyisocyanates can also be used. Other possible isocyanates are indicated, for example, in "Handbook of Plastics, Volume 7, Polyurethanes" (Carl Hanser Verlag, 3rd edition, 1993, sections 3.2 and 3.3.2).

[0018] Preference is given to using isophorone diisocyanate (IPDI) as isocyanate (a), if desired in admixture with modified isophorone diisocyanates, and most preferably isophorone diisocyanate alone, in particular only isophorone diisocyanate.

[0019] As the polyol, two or more polyols (b) comprising at least one polyether polyol (b1) and at least one hydroxyl-terminated rubber (b2) are used.

[0020] In this case, all compounds known in polyurethane chemistry which have at least two (preferably 2 to 8) isocyanate-reactive groups can be used as polyols. These compounds include polyether alcohols, polyester alcohols, polyamines, hydroxyl-terminated polymers (such as hydroxyl-terminated rubbers), and compounds known as chain extenders and crosslinkers. These compounds are described, for example, in "Handbook of Plastics, Volume 7, Polyurethanes" (Carl Hanser Verlag, 3rd edition, 1993, Sections 3.1 and 3.4.3).

[0021] The polyether polyols (b1) preferably have a hydroxyl number of 20 to 100 mg KOH / g, particularly preferably 35 to 80 mg KOH / g, in particular 45 to 65 mg KOH / g, and a functionality of preferably 2 to 3, in particular 2.

[0022] The polyether alcohols that can be used according to the invention are prepared by known methods. For example, they can be prepared by anionic polymerization of alkylene oxides with alkali metal hydroxides (such as sodium hydroxide or potassium hydroxide) or alkali metal alcoholates (such as sodium formate, sodium acetate or potassium acetate or potassium isopropanoate) as catalysts and the addition of at least one leavening agent molecule (preferably with 2 to 3 active hydrogen atoms), or by cationic polymerization with Lewis acids (such as antimony pentachloride, boron fluoride ether, etc.) or bleaching earth as catalysts. Polyether polyols can also be prepared from one or more alkylene oxides containing 2 to 4 carbon atoms in the alkyl group by double metal cyanide catalysis. Tertiary amines can also be used as catalysts, for example triethylamine, tributylamine, trimethylamine, dimethylethanolamine, imidazole or dimethylcyclohexylamine.

[0023] Suitable alkyl oxides are, for example, ethylene oxide, propylene oxide, 1,2-butylene oxide, 1,3-butylene oxide, 2,3-butylene oxide, styrene oxide, tetrahydrofuran or mixtures thereof, preferably ethylene oxide, propylene oxide, 1,2-butylene oxide, tetrahydrofuran or mixtures thereof, in particular tetrahydrofuran. The alkyl oxides can be used individually, alternately or as a mixture.

[0024] As leavening agent molecules, for example, water, aliphatic and aromatic, N-monoalkyl, N,N- and N,N'-dialkyl-substituted diamines, in particular polyols, such as ethylene glycol, 1,2- and 2,3-propanediol, diethylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane; pentaerythritol and mixtures thereof, come into consideration. In this case, in the context of the present invention, the functionality of the polyether polyol (b1) is regarded as the functionality of the leavening agent molecule, even though the actual functionality of the polyether polyol may be lower in practice due to side reactions. Fractional functionalities can be obtained by mixing leavening agent molecules with different functionalities.

[0025] Polytetrahydrofuran (PTHF polyol) can also be used as polyether alcohol. In this case, the number average molecular weight of the polytetrahydrofuran is generally 550 g / mol to 4000 g / mol, preferably 750 g / mol to 3000 g / mol, particularly preferably 800 g / mol to 2500 g / mol.

[0026] The polyether polyols may be used alone or in the form of a mixture.

[0027] One or more hydroxyl-terminated rubbers can be used as hydroxyl-terminated rubber (b2), hydroxyl-terminated rubbers being understood to be all rubbers containing hydroxyl groups, for example nitrile rubbers containing hydroxyl groups (for example as described in US Pat. No. 3,551,472), preferably hydroxyl-terminated polybutadiene (HTPB).

[0028] Liquid hydroxy-terminated polybutadiene (HTPB) has long been known and is used as a polyol component in polyurethanes. Commercial products are obtainable by free radical polymerization (see US 3965140) or ionic polymerization (see DD 160223) of 1,3-butadiene. To obtain HTPB, certain starting and terminating agents are used. Depending on the preparation process, polyols with different numbers of functional groups are obtained. Depending on the degree of epoxidation and epoxide opening, the polybutadiene alcohols obtained by reaction of polymer analogs contain different numbers of active hydroxyl groups and therefore have different functionalities. In order to improve the compatibility with polyether alcohols (b1) and isocyanates (a), the hydroxy-terminated polybutadiene can also be modified with alkylene oxides or cyclic esters (such as ε-caprolactone). Such compounds are described, for example, in EP 3183282. Unfunctionalized HTPB is preferably used.

[0029] Commercially available hydroxy-terminated polybutadienes include Cray Valley's and Products such as LBH-P 2000 or R45V. Rizi-10 nut oil polyols such as Alberdingk Boley Products such as or Baker Castor Oil Company Products such as

[0030] For anionic preparation, the hydroxyl functionality of the hydroxyl-terminated rubber used is preferably between 1.7 and 2.2, and for free radical preparation, it is preferably between 2.2 and 2.8. If an epoxy-terminated impact modifier is used in a two-component epoxy resin adhesive, it is preferred to use a hydroxyl-terminated rubber with a hydroxyl functionality of less than or equal to 2, especially hydroxy-terminated butadiene. If an epoxy-terminated impact modifier is used in a one-component epoxy resin adhesive, it is preferred to use a hydroxyl-terminated rubber with a hydroxyl functionality between 2.4 and 2.8, especially hydroxy-terminated butadiene. The above-mentioned preferred hydroxyl functionality for two-component and one-component epoxy resin adhesives can also be achieved by mixing two hydroxyl-terminated rubbers (especially hydroxyl-terminated polybutadiene).

[0031] The weight ratio of polyether polyol to hydroxyl terminated rubber is preferably between 7:3 and 2:8, particularly preferably 7:3 to 4:6, more preferably 7:3 to 5:5, more particularly preferably 6:4 to 2:8, and particularly preferably 6:4 to 3:7. In this way, the mechanical properties of the cured adhesive, especially the impact peel resistance at -30°C, can be improved.

[0032] As polyols, in particular as polyols (b1) and (b2), preferably, are: a mixture of epoxy liquid resin and polyol prepared from bisphenol-A and epichlorohydrin (such as Epikote 828LVEL) in a weight ratio of 40:60, having a haze value of between 50 and 100 when hydroxyl-terminated rubber (b2) is used as polyol, and / or a haze value of between 0 and 5 when polyether polyol is used as polyol (b1), measured according to ASTM D1003-11e1.

[0033] The polyisocyanate (a) and the polyol (b) are then reacted to form an isocyanate-terminated prepolymer. For this purpose, the polyisocyanate (a) and the polyol (b) are mixed in such a ratio that the molar ratio of isocyanate groups to hydroxyl groups is from 10:1 to 1.5:1, preferably from 5:1 to 1.8:1, particularly preferably from 3:1 to 1.9:1. The reaction is usually carried out at a temperature of 30° C. to 100° C., preferably at about 80° C., preferably in the presence of conventional polyurethane catalysts. Such catalysts are described, for example, in “Handbook of Plastics, Volume 7, Polyurethanes” (Carl Hanser Verlag, 3rd edition, 1993, Section 3.4.1).

[0034] In this case, for example, organometallic compounds, preferably organotin compounds, such as tin(II) salts of organic carboxylic acids, such as tin(II) acetate, tin(II) octoate, tin(II) hexanoate and tin(II) laurate, and dialkyltin(IV) salts of organic carboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin maleate and dioctyltin diacetate, and bismuth carboxylates, such as bismuth(III) neodecanoate, bismuth 2-acetylhexanoate and bismuth octoate or mixtures thereof come into consideration. Other possible catalysts are strongly basic amine catalysts. Examples include amides such as 2,3-dimethyl-3,4,5,6-tetrahydropyrimidine, including tertiary amines such as triethylamine, tributylamine, dimethylbenzylamine, N-methyl, N-ethyl, N-cyclohexylmorpholine, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylbutylenediamine, N,N,N',N'-tetramethylhexanediamine, pentamethyldiethylenetriamine, tetramethyldiaminoethyl ether, bis(dimethylaminopropyl)urea, dimethylpiperazine, 1,2-dimethylimidazole, 1-azabicyclo-(3,3,0)-octane, and preferably 1,4-diazabicyclo-(2,2,2)-octane and alkanolamine compounds such as triethanolamine, triisopropanolamine, N-methyl and N-ethyldiethanolamine and dimethylethanolamine. The catalysts may be used alone or as a mixture. It is particularly preferred to use only metal catalysts to prepare the prepolymers.

[0035] The content of free isocyanate groups in the isocyanate prepolymer is generally between 1 wt.% and 6 wt.% isocyanate, preferably 1.5 wt.% to 4 wt.% free isocyanate groups.

[0036] The isocyanate-terminated prepolymer is then reacted with the polyepoxide (c) in a further step in the presence of an ionic liquid to form an epoxy-terminated impact modifier. In this case, the reaction is preferably carried out at a temperature of 120°C to 250°C.

[0037] Any aliphatic, cycloaliphatic, aromatic and / or heterocyclic compound having at least two epoxy groups can be used as polyepoxide (c). Preferred epoxides suitable for serving as component (c) have 2 to 4, preferably 2, epoxy groups per molecule and have an epoxy equivalent weight of 90 g / eq to 500 g / eq, preferably 140 g / eq to 220 g / eq.

[0038] Suitable polyepoxides are, for example, polyglycidyl ethers of polyphenols such as catechol, resorcinol, hydroquinone, 4,4'-dihydroxydiphenylpropane (bisphenol A), 4,4'-dihydroxy-3,3'-dimethyldiphenylmethane, 4,4'-dihydroxydiphenylmethane (bisphenol F), 4,4'-dihydroxydiphenylcyclohexane, 4,4'-dihydroxy-3,3'-dimethyldiphenylpropane, 4,4'-dihydroxybiphenyl , 4,4'-dihydroxydiphenyl sulfone (bisphenol S), tris-(4-hydroxyphenyl)-methane, chlorination products and bromination products of the above diphenols, novolac (i.e. the product formed by the reaction of monohydric or polyhydric phenols and / or cresols with aldehydes, especially formaldehyde, in the presence of an acidic catalyst in an equivalent ratio of less than 1:1), diphenols obtained by esterifying 2 moles of a sodium salt of an aromatic oxycarboxylic acid with one mole of a dihaloalkane or a dihalodialkyl ester (see British Patent Case 1017612), or polyphenols obtained by condensing phenols with long-chain halogenated alkanes containing at least two halogen atoms (see GB-PS1024288). Also mentioned are: polyepoxides based on aromatic amines and epichlorohydrin, for example N-di-(2,3-epoxypropyl)-aniline, N,N′-dimethyl-N,N′-diepoxypropyl-4,4′-diaminodiphenylmethane, N,N-diepoxypropyl-4-amino-phenyl glycidyl ether (cf. GB-PS 772 830 and 816 923).

[0039] In addition, glycidyl esters of aromatic, aliphatic and alicyclic polycarboxylic acids, such as diglycidyl phthalate, diglycidyl isophthalate, diglycidyl terephthalate, diglycidyl adipate, and glycidyl esters of the reaction products of 1 mol of an aromatic or alicyclic dicarboxylic anhydride with 1 / 2 mol of a diol or 1 / n mol of a polyol containing n hydroxyl groups, or diglycidyl hexahydrophthalate, which may be optionally substituted with a methyl group, can be used.

[0040] Glycidyl esters of polyols, such as glycidyl ester of 1,4-butanediol ( DY-D, Huntsman), glycidyl ester of 1,4-butenediol, glycidyl ester of glycerol, glycidyl ester of trimethylolpropane ( DY-T / CH, Huntsman), glycidyl ester of pentaerythritol, and glycidyl ester of polyethylene glycol. In addition, triglycidyl isocyanurate, N,N'-diepoxypropoxyamide, polyglycidyl sulfide of polythiol, such as bismercaptomethylbenzene, diglycidyl trimethylene trisulfone, and polyglycidyl ether based on hydantoin can also be used.

[0041] Finally, it is also possible to use epoxidation products of polyunsaturated compounds, such as vegetable oils and their conversion products. It is also possible to use epoxidation products of dienes and polyolefins, such as butadiene, vinylcyclohexane, 1,5-cyclooctadiene, 1,5,9-cyclododecatriene, polymers and copolymers containing double bonds which are still epoxidizable, for example based on polybutadiene, polyisoprene, butadiene-styrene copolymers, divinylbenzene, dicyclopentadiene, unsaturated polyesters, and also epoxidation products of olefins which are obtainable by Diels-Alder addition and which are subsequently converted into polyepoxides by epoxidation with peroxides, or compounds which contain two cyclopentene or cyclohexene rings connected by a bridge atom or a bridge atom group.

[0042] Furthermore, it is also possible to use polymers of unsaturated monoepoxides, for example polymers of glycidyl methacrylate or allyl glycidyl ether.

[0043] According to the invention, the following polyepoxides or mixtures thereof are preferably used as component (c):

[0044] Polyglycidyl ethers of polyphenols, especially polyglycidyl ethers of bisphenol A ( GY250, Huntsman; 0162, Bakelite AG; Resin 162, Hexion SpecialtyChemicals GmbH; Eurepox 710, Brenntag GmbH; GY250, Hunstman, DER TM 332, The Dow Chemical Company; A18-00, LEUNA-Harze GmbH) or polyglycidyl ether of bisphenol F (4,4'-dihydroxy-diphenyl-methane, GY281, Huntsman; F 16-01, LEUNA-Harze GmbH; F 17-00, LEUNA-Harze GmbH), polyepoxides based on aromatic amines, in particular bis(N-epoxypropyl)aniline, N,N'-dimethyl-N,N'-diepoxypropyl-4,4'-diaminodiphenylmethane and N,N-diepoxypropyl-4-aminophenyl glycidyl ether; polyglycidyl esters of cycloaliphatic dicarboxylic acids, in particular diglycidyl hexahydrophthalate, and polyepoxides of the reaction products of n mol of hexahydrophthalic anhydride with 1 mol of a polyol having n hydroxyl groups (n=an integer from 2 to 6), in particular polyepoxides of the reaction products of 3 mol of hexahydrophthalic anhydride with 1 mol of 1,1,1-trimethylolpropane; 3,4-epoxycyclohexylmethane-3,4-epoxycyclohexanecarboxylate.

[0045] Particular preference is given to using polyglycidyl ethers of bisphenol A and bisphenol F and novolacs, or mixtures thereof, in particular polyglycidyl ethers of bisphenol F.

[0046] In special cases, liquid polyepoxides or low-viscosity diepoxides, such as bis-(N-epoxypropyl)-aniline or vinylcyclohexane diepoxide, can further reduce the viscosity of an already liquid polyepoxide or convert a solid polyepoxide into a liquid mixture. The polyepoxide (c) preferably contains as few hydroxyl-containing by-products as possible, such as ethylene glycol. In this case, the proportion of hydroxyl-containing by-products is indicated in the hydroxyl number of the polyepoxide (c). The hydroxyl number of the polyepoxide (c) is particularly preferably less than 20 mg KOH / g, in particular less than 10 mg KOH / g.

[0047] Ionic liquids are generally known, widely described and commercially available. For example, ionic liquids suitable for improving the conductivity of polyurethanes are described in EP 2 038 337. In this case, the ionic liquid is a salt of the general formula (I)

[0048]

[0049] Where n is 1, 2, 3 or 4, [A] + represents a quaternary ammonium cation, a carbonyl ammonium cation, a sulfonium ammonium cation or a phosphonium cation, [Y] n- represents a monovalent, divalent, trivalent, or tetravalent anion;

[0050] (B) Mixed salt of general formula (II)

[0051] [A 1 ] + [A 2 ] + [Y] n- (IIa), wherein n = 2;

[0052] [A1 ] + [A 2 ] + [A 3 ] + [Y] n- (IIb), wherein n=3; or

[0053] [A 1 ] + [A 2 ] + [A 3 ] + [A 4 ] + [Y] n- (IIc), wherein n=4 and wherein [A 1 ] + , [A 2 ] + , [A 3 ] + and [A 4 ] + Independently selected from [A] + The group, and [Y] n- has the meaning set forth in clause (A); or

[0054] (C) Mixed salt of general formula (III)

[0055] [A 1 ] + [A 2 ] + [A 3 ] + [M 1 ] + [Y] n- (IIIa), wherein n=4;

[0056] [A 1 ] + [A 2 ] + [M 1 ] + [M 2 ] + [Y] n- (IIIb), wherein n=4;

[0057] [A 1 ] + [M 1 ] + [M 2 ] + [M 3 ] + [Y]n- (IIIc), wherein n=4;

[0058] [A 1 ] + [A 2 ] + [M 1 ] + [Y] n- (IIId), wherein n=3;

[0059] [A 1 ] + [M 1 ] + [M 2 ] + [Y] n- (IIIe), wherein n=3;

[0060] [A 1 ] + [M 1 ] + [Y] n- (IIIf), where n = 2;

[0061] [A 1 ] + [A 2 ] + [M 4 ] 2+ [Y] n- (IIIg), wherein n=4;

[0062] [A 1 ] + [M 1 ] + [M 4 ] 2+ [Y] n- (IIIh), wherein n=4;

[0063] [A 1 ] + [M 5 ] 3+ [Y] n- (IIIi), wherein n=4; or

[0064] [A 1 ] + [M 4 ] 2+ [Y] n- (IIIj), where n=3 and where [A 1 ] + , [A 2 ] +and [A 3 ] + Independently selected from [A] + The group, [Y] n- has the meaning given to it in clause (A) and [M 1 ] + 、[M 2 ] + 、[M 3 ] + is a monovalent metal cation, [M 4 ] 2+ is a divalent metal cation and [M 5 ] 3+ It is a trivalent metal cation.

[0065] The ionic liquid used in the present invention has a melting point in the range of -50°C to 150°C, more preferably -20°C to below 100°C, and even more preferably -20°C to below 80°C. The melting point of the ionic liquid is particularly preferably below 50°C, especially the ionic liquid according to the present invention is liquid at room temperature. Ionic liquids that are liquid at room temperature are easy to process and have excellent antistatic effects.

[0066] Suitable for forming ionic liquid cations [A] + Compounds of this type have been disclosed, for example, in DE 102 02 838 A1. Therefore, such compounds may contain oxygen, phosphorus, sulfur or in particular nitrogen atoms, for example at least one nitrogen atom, preferably 1-10 nitrogen atoms, particularly preferably 1-5 nitrogen atoms, particularly particularly preferably 1-3 nitrogen atoms, in particular 1-2 nitrogen atoms. If necessary, more heteroatoms may also be contained, such as oxygen, sulfur or phosphorus atoms. Nitrogen atoms are suitable carriers of positive charges in ionic liquid cations, and protons or alkyl radicals may be transferred from nitrogen atoms to anions in a balanced state, thereby producing electrically neutral molecules. Positive charges may also be dispersed in the intermediate system.

[0067] If the nitrogen atom is the carrier of the positive charge in the cation of the ionic liquid, then in the process of synthesizing the ionic liquid, the cation can be first generated by quaternizing the nitrogen atom of the amine or nitrogen heterocycle. Quaternization can be carried out by alkylation of the nitrogen atom. Depending on the different alkylating agents used, salts containing different anions can be obtained. If the desired anion cannot be formed during the quaternization process, it can be achieved by further synthesis steps. For example, starting from ammonium halide, the halide can react with Lewis acid, and a complex anion is formed by the halide and Lewis acid in this process. As an alternative, the halide ion can also be replaced by the desired anion. It can be achieved by adding a metal salt to the formed metal halide precipitate, by an ion exchanger or by replacing the halide ion with a strong acid (releasing a hydrohalic acid). For example, a suitable method is described in Angew.Chem. (Applied Chemistry) 2000, 112, pages 3926-3945 and the literature cited therein.

[0068] In principle, all anions can be used as anions. Preferred anions that can be used are described, for example, in EP 2 038 337.

[0069] In the present invention, it is preferred to use substances containing soft cations and / or soft anions as ionic liquids. This means that the cations and / or anions are very stable, for example, by inductive effect and / or dielectric effect. In this case, the cations preferably have electron transfer substituents. The cations preferably contain only electron transfer substituents. The anions preferably have electron-withdrawing substituents. In this case, it is particularly preferred to use the following ionic liquids: the charges of its cations, anions or cations and anions are dispersed by dielectric effect. Therefore, imidazolium, guanidinium or pyrazolium derivatives, particularly imidazolium derivatives, are preferably used as cations. The ionic liquid according to the invention particularly preferably has a cation selected from the group consisting of 1,2,3-trimethylimidazolium, 1,3,4,5-tetramethylimidazolium, 1,3,4-dimethylimidazolium, 1,3,4-trimethylimidazolium, 1,3-dibutyl-2-methylimidazolium, 1,3-dibutylimidazolium, 1,2-dimethylimidazolium, 1,3-dimethylimidazolium, 1-benzyl-3-methylimidazolium, 1-butyl-2,3-dimethylimidazolium, imidazolium, 1-butyl-2-ethyl-5-methylimidazolium, 1-butyl-2-ethylimidazolium, 1-butyl-2-methylimidazolium, 1-butyl-3,4,5-trimethylimidazolium, 1-butyl-3,4-dimethylimidazolium, 1-butyl-3-ethylimidazolium, 1-butyl-3-methylimidazolium, 1-butyl-4-methylimidazolium, 1-butylimidazolium, 1-decyl-3-methylimidazolium, 1-dodecyl-3-methylimidazolium, 1-ethyl 1-hexadecyl-2,3-dimethylimidazolium, 1-hexadecyl-3-methylimidazolium, 1-hexyl-2,3-dimethylimidazolium, 1-hexyl-3-methylimidazolium, 1-methyl-2-ethylimidazolium, 1-methyl-3-octylimidazolium, 1-methylimidazolium, 1-pentyl-3-methylimidazolium, 1-phenylpropyl-3-methylimidazolium, 1-propyl-2,3-dimethylimidazolium Methylimidazolium, 1-tetradecyl-3-methylimidazolium, 2,3-dimethylimidazolium, 2-ethyl-3,4-dimethylimidazolium, 3,4-dimethylimidazolium, 1,2-dimethylpyridinium, guanidinium, hexamethylguanidinium, N,N,N',N'-tetramethyl-N"-ethylguanidinium, N-pentamethyl-N-isopropylguanidine, N-pentamethyl-N-propylguanidine, benzyltriphenylphosphonium, tetrabutylphosphonium, trihexyl(tetradecyl)phosphonium and triisobutyl(methyl)phosphonium.

[0070] The anions of the method according to the invention are preferably selected from the group consisting of acetate, bis(2,4,4-trimethylpentyl)phosphonate, bis(malonic acid)borate, bis(oxalic acid)borate, bis(pentafluoroethyl)phosphonate, bis(phthalic acid)borate, bis(salicylic acid)borate, bis(trifluoromethanesulfonyl)imidate, bis(trifluoromethyl)imidate, borate, bromide, bromoaluminate, carbonate, chloroaluminate, decylbenzenesulfonate, dichloroacetate, dicyanamide, didecylbenzenesulfonate, didodecylbenzenesulfonate, diethyl phosphate, dihydrogen phosphate, dodecylbenzene Sulfonate, ethyl sulfate, ethyl sulfonate, fluoride, hexafluorophosphate, bicarbonate, hydrogen phosphate, hydrogen sulfate, hydrogen sulfite, iodide, methyl sulfate, methyl sulfonate, nitrate, nitrite, phosphate, sulfite, tetracyanoborate, tetrafluoroborate, tetrakis(hydrogensulfate)borate, tetrakis(methylsulfonic acid)borate, thiocyanate, p-toluenesulfonate, trichlorozincate, trifluoroacetate, trifluoromethylsulfonate, tris(heptafluoropropyl)trifluorophosphate, tris(nonafluorobutyl)trifluorophosphate, tris(pentafluoroethyl)trifluorophosphate, tris(pentafluoroethylsulfonyl)trifluorophosphate.

[0071] Anions are particularly preferably hexafluorophosphate, tetrafluoroborate, thiocyanate and dicyanamide, ethyl sulfate, diethyl phosphate, methyl sulfate, bromide, iodide, p-toluenesulfonate and methanesulfonate, especially based on ethyl sulfate, thiocyanate, bromide or dicyanamide, very particularly preferably bromide.

[0072] As the ionic liquid of the present invention, 1-ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium methanesulfonate, 1-butyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-butyl-3-methylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium thiocyanate, 1-butyl 1-ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium p-toluenesulfonate and / or 1-butyl-3-methylimidazolium p-toluenesulfonate.

[0073] The ionic liquid of the present invention is particularly preferably selected from the group consisting of 1-ethyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium ethylsulfate, 1-ethyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, and a mixture consisting of at least two components of this group. In particular, 1-butyl-3-methylimidazolium bromide is used as the ionic liquid.

[0074] According to the invention, the content of the ionic liquid in the antistatic or conductive polyurethane is preferably 0.001 wt.% to 2 wt.%, more preferably 0.01 wt.% to 1.5 wt.%, more particularly preferably 0.05 wt.% to 1.0 wt.%, and particularly preferably 0.05 wt.% to 0.5 wt.%, in each case based on the total weight of the isocyanate-terminated prepolymer and the polyepoxide (c). In this case, the ionic liquids used can be used alone or in the form of a mixture.

[0075] In the presence of an ionic liquid, the reaction of the isocyanate-terminated prepolymer with the polyepoxide (c) to form an epoxy-terminated impact modifier can be a partial reaction or a complete reaction, wherein in the case of a complete reaction, substantially all isocyanate groups in the prepolymer react with epoxy groups, while in the case of a partial reaction, isocyanate groups still remain. According to the present invention, the proportion of unreacted isocyanate groups in the impact modifier is preferably less than 1 wt.%, particularly preferably less than 0.1 wt.%, and especially less than 0.01 wt.%, based on the total weight of the epoxy-terminated impact modifier. In a particularly preferred embodiment, the epoxy-terminated impact modifier does not contain isocyanate groups.

[0076] The epoxy-terminated impact modifier prepared according to the method of the present invention can be added to a one-component or two-component epoxy resin composition, preferably to a one-component or two-component epoxy resin adhesive, to improve the impact strength of the cured epoxy resin matrix. Another application area of ​​the epoxy-terminated impact modifier according to the present invention is for use in epoxy-containing polyurethanes and polyisocyanates. For example, such compounds are described in WO 2015078740.

[0077] The epoxy-terminated impact modifier according to the invention is preferably used by adding it to a liquid starting component of the epoxy resin composition; as an alternative, the impact modifier can also be added as a separate component of the epoxy resin composition. In this case, the proportion of the impact modifier according to the invention is preferably 1 wt.% to 75 wt.%, particularly preferably 10 wt.% to 60 wt.%, and in particular 25 wt.%-55 wt.%, based on the total weight of the epoxy resin composition. The epoxy resin composition obtained according to the invention has better impact strength, at least constant tensile strength and lower crack propagation. In this case, the glass transition temperature is only slightly affected compared to epoxy resin compositions without impact modifiers, i.e., when 20 wt.% of impact modifier is used (based on the total weight of epoxy resin composition and impact modifier), the glass transition temperature is reduced, and the reduction is preferably less than 20°C, particularly preferably less than 10°C, and in particular less than 5°C compared to epoxy resin compositions without impact modifiers. Furthermore, the viscosity of the epoxy resin composition according to the present invention containing 20 wt.% of the impact modifier at 40° C. preferably increases by less than 50%, particularly preferably by less than 30%, and especially by less than 10%, compared to the initial value without the impact modifier.

[0078] Hereinafter, the present invention will be described by way of examples.

[0079] Ethylene oxide determination (EEW ​​determination) Description:

[0080] The oxirane ("epoxy") character of a compound is determined by epoxide titration. The resulting epoxide value (% EpO) indicates how many grams of oxirane oxygen are present in 100 grams of sample.

[0081] The indicator is crystal violet. The determination requires the absence of water, alkali and amine.

[0082] Reagents:

[0083] (1) 0.1-N perchloric acid (Merck) glacial acetic acid solution

[0084] (2) Tetraethylammonium bromide (Fluka), i.e., a solution of 100 g tetraethylammonium bromide in 400 ml glacial acetic acid

[0085] (3) Crystal violet (Merck); dissolve 0.2 g of crystal violet in 100 ml of glacial acetic acid to prepare an indicator solution.

[0086] operate:

[0087] Place 0.2 g to 0.5 g of a sample containing ethylene oxide in an Erlenmeyer flask. Dissolve the sample in 50 ml of anhydrous acetone. Then add 10 ml of tetraethylammonium bromide solution and 3 drops of crystal violet solution. Titrate the mixture with 0.1-N perchloric acid glacial acetic acid solution. When the color changes from blue to green, the end point is reached.

[0088] Before the actual titration, a blank sample (without ethylene oxide compound) was taken to eliminate measurement errors.

[0089] Evaluate:

[0090] The calculation formula of epoxy content %EpO is as follows: %EpO = [(ab) + 0.160] / E

[0091] a: = 0.1N perchloric acid consumed during titration (unit: ml)

[0092] b: = 0.1N perchloric acid consumed when taking blank sample (unit: ml)

[0093] E: = sample weight (unit: g)

[0094] Epoxy equivalent weight (EEW) is calculated using the following formula:

[0095] EEW=1600 / %EpO

[0096] The unit of EEW is (g / equivalent).

[0097] The isocyanate content (unit: wt. %) was determined by back titrating the corresponding samples with an excess of 1 M di-n-butylamine and 1 molar hydrochloric acid in chlorobenzene.

[0098] The tensile test was carried out according to DIN EN ISO 527 standard to obtain the tensile strength, elastic modulus and elongation at break, with a test speed of 20 mm / min.

[0099] Charpy impact strength complies with DIN EN ISO 179-1 / 1fU.

[0100] Fracture toughness K measured by OCT (optical crack tracing) at Frauenhofer IAP-PYCO according to ISO 13586 and ASTM D5045 1C and fracture energy G 1C .

[0101] To prepare the epoxy resin, the following raw materials were used:

[0102]

[0103] Example 1: Isocyanate-terminated prepolymer 1

[0104] 416.61 g PolyTHF 2000 and 416.61 g Polyvest EP HT were dried under vacuum at 90° C. and stirred for 1 hour. Subsequently, 0.14 g Fomrez UL 28 was added and stirred for 5 minutes. 166.64 g Vestanat IPDI was added and reacted under vacuum at 90° C. for 2 hours. A product with a free isocyanate content of 3.08% (theoretical isocyanate content: 3.00%) was obtained.

[0105] Example 2: Isocyanate-terminated prepolymer 2

[0106] 498.71 g PolyTHF 2000 and 332.47 g Polyvest EP HT were dried under vacuum at 90° C. and stirred for 1 hour. Subsequently, 0.08 g Fomrez UL 28 was added and stirred for 5 minutes. 168.73 g Vestanat IPDI was added and reacted under vacuum at 90° C. for 2 hours. A product with a free isocyanate content of 3.15% (theoretical isocyanate content: 3.00%) was obtained.

[0107] Example 3: Isocyanate-terminated prepolymer 3

[0108] 495.82 g PolyTHF 2000 and 330.54 g Krasol LBH-P 2000 were dried under vacuum at 90° C. and stirred for 1 hour. Subsequently, 0.10 g Fomrez UL 28 was added and stirred for 5 minutes. 173.54 g Vestanat IPDI was added and reacted under vacuum at 90° C. for 2 hours. A product with a free isocyanate content of 3.03% (theoretical isocyanate content: 3.00%) was obtained.

[0109] Example 4

[0110] 440 g of DER330 and 0.46 g of EMIM-Br were placed in a 1 L four-necked round-bottom flask equipped with a KPG stirrer, a temperature sensor, a dropping funnel (heatable to 80° C.) and a condenser, and N2 was flushed through the condenser and heated to 160° C. under N2 flushing. Using a dropping funnel, 220 g (0.0770 equivalent of isocyanate) of the isocyanate-terminated prepolymer 1 described in Example 1 were added over 2 hours, in which case the reaction temperature was kept constant at 160-170° C. After complete addition, stirring was continued at the reaction temperature for 30 minutes, and a sample was taken for infrared spectroscopy analysis. The complete reaction of the isocyanate was confirmed by the disappearance of the band at 2270 cm-1 (isocyanate oscillation). The reaction mixture was cooled to about 100° C. and bottled. The EEW of the viscous product obtained was 308.5 and the viscosity was 4250 mPas (measured at 80° C.).

[0111] Example 5

[0112] 440 g of DER330 and 0.46 g of EMIM-Br were placed in a 1 L four-necked round-bottom flask equipped with a KPG stirrer, a temperature sensor, a dropping funnel (heatable to 80° C.) and a condenser, and N2 was flushed through the condenser and heated to 160° C. under N2 flushing. Using a dropping funnel, 220 g (0.0770 equivalent of isocyanate) of the isocyanate-terminated prepolymer 2 described in Example 2 were added over 2 hours, in which case the reaction temperature was kept constant at 160-170° C. After complete addition, stirring was continued at the reaction temperature for 30 minutes, and a sample was taken for infrared spectroscopy analysis. The complete reaction of the isocyanate was confirmed by the disappearance of the band at 2270 cm-1 (isocyanate oscillation). The reaction mixture was cooled to about 100° C. and bottled. The EEW of the viscous product obtained was 286.9 and the viscosity was 3340 mPas (measured at 80° C.).

[0113] Example 6

[0114] 440 g of DER330 and 0.46 g of EMIM-Br were placed in a 1 L four-necked round-bottom flask equipped with a KPG stirrer, a temperature sensor, a dropping funnel (heatable to 80° C.) and a condenser, and N2 was flushed through the condenser and heated to 160° C. under N2 flushing. Using a dropping funnel, 220 g (0.0770 equivalents of isocyanate) of the isocyanate-terminated prepolymer 3 described in Example 3 were added over 2 hours, in which case the reaction temperature was kept constant at 160-170° C. After complete addition, stirring was continued at the reaction temperature for 30 minutes, and a sample was taken for infrared spectroscopy analysis. The complete reaction of the isocyanate was confirmed by the disappearance of the band at 2270 cm-1 (isocyanate oscillation). The reaction mixture was cooled to about 100° C. and bottled. The EEW of the viscous product obtained was 297.0 and the viscosity was 4018 mPas (measured at 80° C.).

[0115] Comparative Example 1: Phenol blocked prepolymer

[0116] 254.44 g PolyTHF 2000 and 254.44 g Polyvest EP HT were dried under vacuum at 90°C and stirred for 1 hour. Subsequently, 0.08 g Fomrez UL 28 was added and stirred for 5 minutes. 102.62 g Vestanat IPDI was added and reacted under vacuum at 90°C for 2 hours. The free isocyanate content was sampled and determined to be 3.05% (theoretical isocyanate content: 3.00%). 138.24 g Cardolite NX 2026 and 0.17 g Fomrez UL 28 were added and reacted under vacuum at 110°C for 2 hours. The reaction of the isocyanate-terminated prepolymer was confirmed by measuring the isocyanate content (<0.3%).

[0117] Comparative Example 2: Toughening modifier according to US005480958

[0118] 123.58 g of Lupranat T 80A and 676.42 g of Lupranol 1000 / 1 were mixed and heated to 80° C. under nitrogen. The reaction was carried out at 90° C. for 9 hours. A prepolymer having a free isocyanate content of 3.74% (theoretical isocyanate content: 3.80%) was obtained. 197.29 g of the obtained prepolymer was mixed with 452.57 g of Epikote 828 and 0.13 g of potassium acetate and heated to 160° C. After heating at 160° C. for one hour, a sample was taken to verify the reaction of the prepolymer by measuring the isocyanate content (0.01%). The EEW value of the obtained viscous product was 280.6.

[0119] The following examples illustrate the use of the toughening modifier in a one-component heat-curing adhesive.

[0120] During preparation, Epikote 828LVEL, the corresponding toughening modifier, Precal 30S and Om-yacarb 5GU were placed in a planetary mixer according to the proportions in the table and heated to 80°C. After mixing the solids, Araldite GT 6071 was added and cooled to 60°C. HDK H18 and Dyhard 100SF and Dyhard UR700 were then added and stirred in a planetary mixer for 1 hour.

[0121] The adhesive was cured at 175°C for 30 minutes.

[0122]

[0123] Comparing Example 7 with Comparative Example 3 (containing the same amount of toughening modifier), and comparing Example 8 with Comparative Example 4 (containing the same amount of toughening modifier), it can be seen that the toughening modifier described in the present invention performs significantly better than the toughening modifier described in US 005480958 in both cases. The impact strength, K1C and G1C all have significantly higher values.

[0124] Comparing Examples 7, 8 and 9 with Comparative Example 5, which represents the prior art of phenol blocked toughening modifiers, the advantages of the toughening modifiers of the present invention can be seen. The epoxy-terminated prepolymers of the present invention can react directly with the epoxy matrix in the adhesive formulation. The phenol blocked prepolymers must first be unblocked at the curing temperature before reacting with the epoxy matrix. The Tg and elastic modulus of Examples 7, 8 and 9 are significantly higher than those of Comparative Example 5.

Claims

1. A method for preparing an epoxy-terminated impact modifier, wherein a) one or more polyisocyanates and b) mixing two or more polyols, said polyols comprising at least one polyether polyol (b1) and at least one hydroxyl-terminated rubber (b2), The molar ratio of isocyanate group to hydroxyl group is 10:1 to 1.5:1, and the reaction generates an isocyanate-terminated prepolymer, and c) reacting the isocyanate-terminated prepolymer with a polyepoxide (c) in the presence of an ionic liquid to form an epoxy-terminated impact modifier.

2. The method according to claim 1, characterized in that The polyisocyanate (a) includes aliphatic polyisocyanates.

3. The method according to claim 1 or 2, characterized in that: The hydroxyl-terminated rubber (b2) is hydroxyl-terminated polybutadiene.

4. The method according to any one of claims 1 to 3, characterized in that The hydroxyl-terminated rubber (b2) has a hydroxyl functionality between 1.7 and 2.

8.

5. The method according to any one of claims 1 to 4, characterized in that The polyether polyol (b1) is an alkoxylation product of a di- to tri-functional leavening agent molecule, wherein the alkylene oxide is selected from the group consisting of ethylene oxide, propylene oxide, 1,2-butylene oxide, tetrahydrofuran or a mixture thereof.

6. The method according to any one of claims 1 to 5, characterized in that The polyether polyol (b1) is polytetrahydrofuran.

7. The method according to any one of claims 1 to 6, characterized in that The polyether polyol (b1) has a hydroxyl value of 20 to 100 mg KOH / g.

8. The method according to any one of claims 1 to 7, characterized in that The polyepoxide is selected from the group consisting of bisphenol A, bisphenol F, phenol formaldehyde or a mixture thereof.

9. The method according to any one of claims 1 to 8, characterized in that The ionic liquid is selected from the group consisting of: 1-Ethyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium methanesulfonate, 1-butyl-3-methylimidazolium methanesulfonate, 1-ethyl-3-methylimidazolium ethyl sulfate, 1-butyl-3-methylimidazolium methyl sulfate, 1-ethyl-3-methylimidazolium diethyl phosphate, 1-butyl-3-methylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium dicyanamide, 1-butyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium thiocyanate, 1-butyl-3-methylimidazolium thiocyanate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium bromide, 1-ethyl-3-methylimidazolium p-toluenesulfonate and 1-butyl-3-methylimidazolium p-toluenesulfonate.

10. The method according to claim 9, characterized in that The ionic liquid contains 1-ethyl-3-methylimidazolium bromide.

11. The method according to any one of claims 1 to 10, characterized in that The reaction of the isocyanate-terminated prepolymer with the epoxy-terminated impact modifier is carried out at a temperature of 120°C to 250°C.

12. Epoxy terminated impact modifier obtainable according to any one of the preceding claims 1 to 11.

13. Use of the epoxy-terminated impact modifier according to claim 12 in a one-component or two-component epoxy resin composition, preferably in a one-component or two-component epoxy resin adhesive, to improve the impact strength of a cured epoxy resin matrix.

14. A one-component or two-component epoxy resin composition comprising at least one epoxy-terminated impact modifier according to claim 12.

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