Wet and heat curable sealing composition

Abstract

The invention relates to a sealing composition comprising:-at least one epoxy-terminated polyurethane prepolymer (A); -a heat-activatable curing agent or accelerator (B) comprising an amidoamine having a primary amino group and a dicyandiamide; an impact modifier (I) which is the reaction product of at least one polymer diol, at least one polyisocyanate and cardanol; and-at least one polyaldimine (PA). The sealing compound composition is suitable for use as a sealing compound in an automotive body.

Description

Field of the Invention

[0001] The present invention particularly relates to the field of sealant compositions for automotive bodywork processing. Prior Art

[0002] In automotive bodywork processing, the various metal sheets are joined together. The metal sheets used are oiled to minimize corrosion as much as possible. In addition, generally, the body is only passed through a CDC bath (CDC = cathodic dip coating) at the end of body assembly, so that the body is coated with a so-called CDC paint and then baked in a CDC oven. A good CDC coating over the entire surface area forms the basis for the long-term use of the vehicle, as it makes an important contribution to corrosion resistance.

[0003] Therefore, a sealant is generally applied to these oiled metal sheets (such as steel substrates), which needs to adhere well to the oiled metal sheets, does not need to be cured with heat or UV radiation before immersion in the paint bath, and still builds strength quickly.

[0004] WO2012 / 084806 provides a thermally curable sealant compound composition with a dual curing mechanism. On the one hand, due to the reaction of polyisocyanate with polyaldehyde imine upon contact with air and / or atmospheric moisture, a skin forms quickly; this ensures that the sealant compound can pass through the CDC bath without damage. The paint can be deposited on the sealant compound with high quality coating. In another step, the sealant compound is cured due to heat (such as heat in a CDC furnace).

[0005] However, in some cases, there are problems with bubble formation in these sealants. In addition, there is still a need to increase the adhesion on oiled metal sheets to meet more demanding requirements in manufacturing. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a one-component sealant composition which has improved adhesion to oiled metal sheets and less bubble formation, for example, no bubbles in the applied bead after 1 - 2 days at room temperature or after 30 minutes at 180°C. At the same time, the sealant composition still maintains good mechanical and storage properties and rapid strength build-up.

[0007] It has surprisingly been found that the wettable and thermally curable sealant composition according to claim 1 achieves this object.

[0008] Therefore, the sealant compound composition is particularly suitable for use as a sealant compound in automotive bodies.

[0009] A further aspect of the present invention is the subject of further independent claims. Particularly preferred embodiments of the present invention are the subject of the dependent claims.

[0010] Method for implementing the present invention

[0011] The present invention relates to a sealant composition curable by moisture and heat, comprising:

[0012] ● At least one epoxy-terminated polyurethane prepolymer (A);

[0013] ● A heat-activatable curing agent or accelerator (B) comprising an amidoamine having a primary amino group and dicyandiamide;

[0014] ● An impact modifier (I) which is a reaction product of at least one polymeric diol, at least one polyisocyanate and cardanol; and

[0015] ● At least one polyaldehyde imine (PA).

[0016] The term "polymer" in this document refers, on the one hand, to a group of macromolecules which are chemically homogeneous but differ in degree of polymerization, molecular weight and chain length and are synthesized by polymerization reactions (polyaddition, addition polymerization, polycondensation). On the other hand, the term also includes derivatives of this group of macromolecules from polymerization reactions, i.e., compounds obtained by reactions (such as addition or substitution of functional groups on a predetermined molecule) and which may be chemically homogeneous or chemically inhomogeneous. The term additionally also includes so-called prepolymers, i.e., reactive oligomer precursors whose functional groups participate in the structure of macromolecules.

[0017] The term "polyurethane polymer" includes all polymers synthesized by the so-called polyaddition method of diisocyanates. This also includes polymers containing few or no urethane groups at all. Examples of polyurethane polymers include polyether polyurethanes, polyester polyurethanes, polyether polyureas, polyureas, polyester polyureas, polyisocyanurates and polycarbodiimides (Houben Weyl "Methoden der organischen Chemie [Methods of Organic Chemistry]," Thieme Verlag, Stuttgart 1987, Volume E20, page 1561).

[0018] In this document, substance names starting with "poly (multi)", such as polyisocyanates, polyaldehyde imines, polyamines, polyols, polythiols or polyglycidyl ethers, refer to substances which formally contain two or more functional groups also occurring in their names per molecule.

[0019] Unless otherwise specified, all industry standards mentioned in this document refer to the versions in effect on the date of first filing.

[0020] The terms "mass" and "weight" are used synonymously herein. Thus, "weight percent" (% weight) is the percent mass fraction, which, unless otherwise stated, refers to the mass (weight) of the total composition or, depending on the context, to the mass (weight) of the entire molecule.

[0021] In the context of polymers, the term "molecular weight" in this document refers to the average molecular weight Mn, which is typically measured by gel permeation chromatography (GPC) relative to polystyrene standards.

[0022] The room temperature in this document is understood to be a temperature of 25 °C.

[0023] The term "vehicle" in this document shall be understood to refer to any means of transportation by water, land, and air. Such means of transportation particularly include ships, wheeled vehicles such as cars, buses, sedans, trucks, and rail vehicles such as trams and railway vehicles.

[0024] The term "primary amino group" in this document refers to an amino group in the form of an NH2 group bonded to an organic group. Thus, a "primary amine" is a molecule having a primary amino group.

[0025] The term "secondary amino group" denotes an amino group in which the nitrogen atom is bonded to two organic groups, which together may also be part of a ring. Thus, a "secondary amine" is a molecule having a secondary amino group.

[0026] The term "tertiary amino group" denotes an amino group in which the nitrogen atom is bonded to three organic groups such that two of these groups may also together form part of a ring ( = tertiary amine nitrogen). Thus, a "tertiary amine" is a molecule having a tertiary amino group.

[0027] "Aliphatic" refers to an amine or amino group in which the nitrogen atom is bonded only to aliphatic, cycloaliphatic, or araliphatic groups.

[0028] The term "epoxide group" or "epoxy group" shall be understood to refer to the structural unit

[0029] "Glycidyl ether" refers to an ether of 2,3-epoxy-1-propanol (glycidol).

[0030] The dashed lines in the formulas herein represent the bonds between the respective substituents and the respective molecular groups in each case.

[0031] The wettable and heat-curable sealing composition is a one-component composition.

[0032] The "one-component" composition in this text refers to a curable composition in which all components of the composition are mixed and stored together in the same container, and which is stable upon long-term storage at room temperature, so that their use properties or application properties hardly or do not undergo significant changes due to storage, and such a composition cures by the action of moisture and / or heat after application.

[0033] At least one epoxy-capped polyurethane prepolymer (A) used in the compositions curable by moisture and heat of the present invention refers to a polyurethane prepolymer containing isocyanate groups, which is partially capped with epoxides and thus still has a certain content of free isocyanate groups, preferably 0.8% to 3.0% by weight, preferably 1.0% to 2.5% by weight, more preferably 1.5% to 2.0% by weight of free NCO groups, based on the total weight of the polyurethane prepolymer (A). Therefore, the epoxy-capped polyurethane polymer used here is different from a simple mixture of an epoxy resin and a polyurethane prepolymer containing isocyanate groups.

[0034] In the compositions curable by moisture and heat of the present invention, it is advantageous that at least one epoxy-capped polyurethane prepolymer (A) is used in an amount of 35-60% by weight, preferably 40-55% by weight.

[0035] In one embodiment, the epoxy-capped polyurethane prepolymer (A) can be represented by the following formula (IVa):

[0036]

[0037] where R 1 is a linear or branched polyurethane prepolymer PU1 capped with n + m isocyanate groups after removing all terminal isocyanate groups;

[0038] Each R 2 is independently a group of formula (II)

[0039]

[0040] where in each case, R 4 is the moiety of an aliphatic, alicyclic, aromatic or araliphatic epoxide containing primary or secondary hydroxyl groups after removing hydroxide and epoxide groups;

[0041] p = 1, 2 or 3;

[0042] n and m are each a value from 1 to 7, provided that 2 ≤ (m + n) ≤ 8.

[0043] R 1The polyurethane prepolymer PU1 on which it is based can be prepared from at least one diisocyanate or triisocyanate, or from a polymer Q having terminal amino, thiol or hydroxyl groups PM and / or from a polyphenol Q PP prepared, with substituents if appropriate.

[0044] Suitable diisocyanates are aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, especially commercially available products such as methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), toluidine diisocyanate (TODI), isophorone diisocyanate (IPDI), trimethylhexamethylene diisocyanate (TMDI), 2,5- or 2,6-bis(isocyanatomethyl)bicyclo[2.2.1]heptane, naphthalene-1,5-diisocyanate (NDI), dicyclohexylmethane diisocyanate (H 12 MDI), p-phenylene diisocyanate (PPDI), m-tetramethylxylylene diisocyanate (TMXDI), etc., and their dimers. Preferred are HDI, IPDI, MDI or TDI.

[0045] Suitable triisocyanates are trimers or biurets of aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, especially isocyanurates and biurets of the diisocyanates described in the previous paragraph.

[0046] Of course, suitable mixtures of diisocyanates or triisocyanates can also be used.

[0047] Particularly suitable polymers Q having terminal amino, thiol or hydroxyl groups PM are polymers Q having two or three terminal amino, thiol or hydroxyl groups PM .

[0048] Polymer Q PM advantageously has an equivalent weight of NCO-reactive groups of 300 to 6000, especially 600 to 4000, preferably 700 to 2200 g / equivalent.

[0049] Suitable polymers Q PM are polyols, such as the following commercially available polyols, or any desired mixture thereof:

[0050] - Polyalkylene oxide polyols, also known as polyether polyols, which are polymerization products of ethylene oxide, 1,2-propylene oxide, 1,2- or 2,3-butylene oxide, tetrahydrofuran or mixtures thereof, and if appropriate, are polymerized with the help of initiator molecules having two or three active H atoms. Examples of such initiators are water or compounds having two or three OH groups. The materials used can be polyalkylene oxide polyols having low unsaturation (measured according to ASTM D2849-69 and expressed in milliequivalent unsaturation per gram of polyol (meq / g)), which are prepared, for example, with the aid of so-called double metal cyanide complex catalysts (abbreviated as DMC catalysts), or polyalkylene oxide polyols having higher unsaturation, which are prepared, for example, with the aid of anionic catalysts such as NaOH, KOH or alkali metal alcoholates. Particularly suitable materials are polypropylene glycols and polypropylene triols having an unsaturation of less than 0.02 meq / g and a molecular weight in the range of 1000 to 30000 daltons, polybutylene glycols and triols, polypropylene glycols and triols having a molecular weight of 400 to 8000 daltons, and substances called "EO-capped" (ethylene oxide-capped) polyoxypropylene glycols or polyoxypropylene triols. The latter are specific polyoxypropylene polyoxyethylene polyols, which are obtained, for example, by alkoxylating pure polyoxypropylene polyols with ethylene oxide after the end of the polypropoxylation reaction, so that the product has primary hydroxyl groups;

[0051] - Hydroxyl-terminated polybutadiene polyols, such as those produced via the polymerization of 1,3-butadiene and allyl alcohol or via the oxidation of polybutadiene, and also their hydrogenated products;

[0052] - Styrene-acrylonitrile grafted polyether polyols, such as those offered by Elastogran ;

[0053] - Polyhydroxyl-terminated acrylonitrile / butadiene copolymers, such as those obtainable from carboxyl-terminated acrylonitrile / butadiene copolymers (available commercially as CTBN from Nanoresins AG, Germany) and those obtained from epoxides or amino alcohols;

[0054] - Polyester polyols, which are prepared, for example, from di- to trihydric alcohols (such as 1,2-ethanediol, diethylene glycol, 1,2-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, glycerol, 1,1,1-trimethylolpropane or mixtures of the above alcohols) using organic dicarboxylic acids or their acid anhydrides or esters (such as succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedioic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid and hexahydrophthalic acid or mixtures of the above acids), and also polyester polyols derived from lactones, such as ε-caprolactone;

[0055] - Polycarbonate polyols, such as those obtainable by the reaction of, for example, the above alcohols used in the structure of polyester polyols with dialkyl carbonates, diaryl carbonates or phosgene.

[0056] Polymer Q PM Advantageously, it is at least a difunctional OH-equivalent of 300 - 6000 g / OH-equivalent, especially 600 - 4000 g / OH-equivalent, preferably 700 - 2200 g / OH-equivalent. Other advantageous polyols are selected from polyethylene glycols, polypropylene glycols, polyethylene glycol - polypropylene glycol block copolymers, polybutylene glycols, hydroxyl-terminated polybutadienes, hydroxyl-terminated butadiene / acrylonitrile copolymers, hydroxyl-terminated synthetic rubbers, their hydrogenated products and mixtures of the above polyols.

[0057] Other polymer Q that can also be used PM is at least a bifunctional amino-terminated polyethylene ether, polypropylene ether (such as those sold by Huntsman under ), polybutylene ether, polybutadiene, butadiene / acrylonitrile copolymers (such as those sold by NanoResins AG (Germany) under ATBN), and other amino-terminated synthetic rubbers or mixtures of the mentioned components.

[0058] For certain applications, particularly suitable polymer Q PM is hydroxylated polybutadiene or polyisoprene, or a partially or fully hydrogenated reaction product thereof.

[0059] In addition, polymer Q PM can also be chain-extended in a manner known to those skilled in the art via the reaction of polyamines, polyols and polyisocyanates, especially diamines, diols and diisocyanates.

[0060] For the chain-extension reaction, diols and / or diamines and diisocyanates are particularly preferred. Of course, those skilled in the art know that higher functionality polyols, such as trimethylolpropane or pentaerythritol, or higher functionality polyisocyanates, such as isocyanurates of diisocyanates, can also be used for the chain-extension reaction.

[0061] In the case of polyurethane prepolymers PU1, especially in the case of chain-extended polyurethane prepolymers, it is advantageous to ensure that the prepolymers do not have an excessively high viscosity, especially if higher functionality compounds are used in the chain extension reaction, because this may cause difficulties in their reaction to obtain the polymer of formula (IVa) or in the application of the composition.

[0062] Preferred polymer Q PM is a polyol having a molecular weight of 600 to 6000 daltons, selected from polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol block polymers, polybutylene glycol, hydroxyl-terminated polybutadiene, hydroxyl-terminated butadiene-acrylonitrile copolymers, and mixtures thereof.

[0063] Particularly preferred polymer Q PM is an α,ω-dihydroxypolyalkylene glycol having a C2-C6 alkylene or a mixed C2-C6 alkylene and terminated by an amino, thiol or preferably hydroxyl group. Particularly preferred is polypropylene glycol or polybutylene glycol. Particularly preferred is poly(oxytetramethylene) glycol terminated by a hydroxyl group.

[0064] Bisphenols, triphenols and tetraphenols are particularly suitable as polyphenol Q PP . This refers not only to unsubstituted phenols, but also, if appropriate, to substituted phenols. The nature of the substitution can be very different. This particularly refers to substitution directly on the aromatic ring bonded to the phenolic OH group. In addition, the phenols here are not only mononuclear aromatic compounds, but also polynuclear or fused aromatic compounds or heteroaromatic compounds having a phenolic OH group directly on the aromatic or heteroaromatic system.

[0065] The nature and position of this type of substituent are one of the factors affecting the reaction with the isocyanate required for the formation of polyurethane prepolymer PU1.

[0066] Bisphenols and triphenols are particularly suitable. Examples of suitable bisphenols or triphenols are 1,4-dihydroxybenzene, 1,3-dihydroxybenzene, 1,2-dihydroxybenzene, 1,3-dihydroxytoluene, 3,5-dihydroxybenzoate, 2,2-bis(4-hydroxyphenyl)propane ( = bisphenol A), bis(4-hydroxyphenyl)methane ( = bisphenol F), bis(4-hydroxyphenyl)sulfone ( = bisphenol S), naphthoresorcinol, dihydroxynaphthalene, dihydroxyanthraquinone, dihydroxybiphenyl, 3,3-bis(p-hydroxyphenyl)phthalide, 5,5-bis(4-hydroxyphenyl)hexahydro-4,7-methanoindane, phenolphthaleine, fluorescein, 4,4'-[bis(hydroxyphenyl)-1,3-phenylenebis(1-methylethylidene)] ( = bisphenol M), 4,4'-[bis(hydroxyphenyl)-1,4-phenylenebis(1-methylethylidene)] ( = bisphenol P), 2,2'-diallylbisphenol A, diphenols and xylenols produced by the reaction of phenol or cresol with diisopropylbenzene, phloroglucinol, gallate, phenol novolac, cresol novolac with an OH functionality of 2.0 - 3.5, respectively, and all isomers of the above compounds.

[0067] In a first embodiment, the polyurethane prepolymer PU1 is prepared from at least one diisocyanate or triisocyanate, and a polymer Q having terminal amino, thiol or hydroxyl groups PM The polyurethane prepolymer PU1 is prepared in a manner known to those skilled in the polyurethane art, in particular by using a diisocyanate or triisocyanate in stoichiometric excess based on the amino, thiol or hydroxyl groups of the polymer Q PM The polyurethane prepolymer PU1 is prepared in a manner known to those skilled in the polyurethane art, in particular by using a diisocyanate or triisocyanate in stoichiometric excess based on the amino, thiol or hydroxyl groups of the polymer Q

[0068] In a second embodiment, the polyurethane prepolymer PU1 is prepared from at least one diisocyanate or triisocyanate and, if appropriate, a polyphenol Q having substituents PP The polyurethane prepolymer PU1 is prepared in a manner known to those skilled in the polyurethane art, in particular by using a diisocyanate or triisocyanate in stoichiometric excess based on the phenolic groups of the polyphenol Q PP The polyurethane prepolymer PU1 is prepared in a manner known to those skilled in the polyurethane art, in particular by using a diisocyanate or triisocyanate in stoichiometric excess based on the phenolic groups of the polyphenol Q

[0069] In a third embodiment, the polyurethane prepolymer PU1 is prepared from at least one diisocyanate or triisocyanate and is also prepared from a polymer Q having terminal amino, thiol or hydroxyl groups PM and is also prepared from, if appropriate, a polyphenol Q having substituents PP Various possibilities are available for preparing the polyurethane prepolymer PU1 from at least one diisocyanate or triisocyanate, and a polymer Q having terminal amino, thiol or hydroxyl groups PM and / or from, if appropriate, a polyphenol Q having substituents PP to prepare the polyurethane prepolymer PU1.

[0070] The partially epoxy group-terminated polyurethane prepolymer of formula (IVa) can be prepared from a polyurethane prepolymer PU1 having isocyanate groups and having formula (III)

[0071]

[0072] by reacting with a suitable amount of a monohydroxy epoxide of formula (V).

[0073]

[0074] The monohydroxy epoxide of formula (V) has 1, 2 or 3 epoxy groups. The hydroxy group of the monohydroxy epoxide (V) can be a primary or secondary hydroxy group.

[0075] These monohydroxy epoxides can be prepared, for example, by the reaction of a polyol with epichlorohydrin. As a function of the reaction carried out between the polyol and epichlorohydrin, the corresponding monohydroxy epoxides are also produced as by-products in various concentrations. These can be separated by conventional separation operations. However, it is generally possible to simply use the product mixture obtained in the glycidylation reaction of the polyol and consisting of polyols that have reacted completely or partially to give glycidyl ethers. Examples of these hydroxylated epoxides are butanediol monoglycidyl ether (present in butanediol diglycidyl ether), hexanediol monoglycidyl ether (present in hexanediol diglycidyl ether), cyclohexanedimethanol glycidyl ether, trimethylolpropane diglycidyl ether (in the form of a mixture present in trimethylolpropane triglycidyl ether), glycerol diglycidyl ether (in the form of a mixture present in glycerol triglycidyl ether), pentaerythritol triglycidyl ether (in the form of a mixture present in pentaerythritol tetraglycidyl ether). Trimethylolpropane diglycidyl ether is preferably used, which is present in a relatively high proportion in conventionally produced trimethylolpropane triglycidyl ether.

[0076] However, other similar hydroxylated epoxides can also be used, especially glycidol, 3-glycidyloxybenzyl alcohol or hydroxymethylcyclohexene oxide. Further preferred are the β-hydroxy ethers of formula (IX), which are present in commercially available liquid epoxy resins prepared from bisphenol A (R = CH3) and epichlorohydrin in an amount of about 15%, and the corresponding β-hydroxy ethers of formula (IX) formed during the reaction of bisphenol F (R = H) or a mixture of bisphenol A and bisphenol F with epichlorohydrin.

[0077]

[0078] Also further preferred are the distillation residues produced during the production of high-purity, distilled liquid epoxy resins. These distillation residues have a hydroxylated epoxide concentration 1-3 times higher than that of commercially available undistilled liquid epoxy resins. Also below, a very large variety of epoxides having β-hydroxy ether groups can be used, which are produced by the reaction of (poly)epoxides with substoichiometric amounts of monofunctional nucleophiles such as carboxylic acids, phenols, thiols or secondary amines.

[0079] The free primary or secondary OH-functional groups of the monohydroxy epoxides of formula (V) allow for an effective reaction with the terminal isocyanate groups of the prepolymer without the need to use a disproportionately large excess of epoxy component.

[0080] Importantly, the wettable and thermally curable sealant composition of the present invention comprises a thermally activatable curing agent or accelerator (B) comprising an amidoamine having a primary amino group and dicyandiamide.

[0081] The amidoamine having a primary amino group is preferably an amidoamine obtainable by the reaction of phthalic anhydride with a polyamine having a primary amino group, especially diethylenetriamine (DETA) or triethylenetetramine (TETA).

[0082] Dicyandiamide can be present in a finely divided form and has an average particle size of <12 μm, especially 1-10 μm, preferably 5-9 μm. The particle size is determined here by sieving.

[0083] The inventors have found that the use of a specific combination of an amidoamine having a primary amino group and dicyandiamide as a thermally activatable curing agent or accelerator in the sealant composition of the present invention can lead to a significant improvement in adhesion to oiled plates and mechanical properties after curing.

[0084] Advantageously, the thermally activatable curing agent or accelerator (B) comprises 1.0-3.3% by weight, preferably 1.5-3.0% by weight, of an amidoamine having a primary amino group and 0.05-0.8% by weight, preferably 0.12-0.55% by weight, of dicyandiamide, each based on the total weight of the sealant composition. It has been found that less than 0.05% by weight of dicyandiamide in the composition may lead to too low a tensile strength, while more than 0.8% by weight may overly impair the elongation at break. By using the required amounts of dicyandiamide in combination with the amidoamine having a primary amino group, the overall mechanical properties can be well balanced.

[0085] The impact modifier (I) required in the curable composition of the present invention is the reaction product of at least one polymer diol, at least one polyisocyanate and cardanol.

[0086] In this reaction, the polymeric diol is preferably reacted with the polyisocyanate in the first step to produce an isocyanate-functional polyurethane prepolymer. The isocyanate groups of the polyurethane prepolymer are then preferably blocked with cardanol to produce the final impact modifier I. The impact modifier I preferably no longer contains a measurable amount of isocyanate groups. In particular, it is preferred that at least 75%, especially at least 90%, preferably at least 99% of all remaining isocyanate groups of the prepolymer are blocked with cardanol after the reaction.

[0087] The isocyanate group-containing prepolymer for the impact modifier I is obtained in particular by the reaction of at least one monomeric polyisocyanate (especially a diisocyanate) and at least one suitable diol. This reaction is preferably carried out at a temperature of 20 - 160 °C, especially 40 - 140 °C, in the absence of moisture and, if appropriate, in the presence of a suitable catalyst.

[0088] The NCO / OH ratio is preferably 1.1 / 1 - 10 / 1, preferably 1.3 / 1 - 10 / 1. The monomeric polyisocyanate remaining in the reaction mixture after the reaction of the OH groups can be removed, especially by distillation.

[0089] In the case of removing the excess monomeric polyisocyanate by distillation, the NCO / OH ratio in the reaction is preferably 3 / 1 to 10 / 1, especially 4 / 1 to 7 / 1, and the isocyanate group-containing prepolymer obtained after distillation preferably contains at most 0.5% by weight, particularly preferably at most 0.3% by weight, of the monomeric polyisocyanate.

[0090] In the case where no excess monomeric polyisocyanate is removed from the prepolymer, the NCO / OH ratio in the reaction is preferably in the range of 1.3 / 1 to 2.5 / 1. Such a prepolymer particularly contains at most 3% by weight, preferably at most 2% by weight, of the monomeric polyisocyanate.

[0091] The preferred impact modifier I is a polymer of formula (IV).

[0092]

[0093] In this formula, x and x' are each independently 0 or 1, preferably 1, provided that at least one, preferably both, of x and x' is not 0;

[0094] R 5 is a linear polyurethane prepolymer containing at least x + x' terminal isocyanate groups after removing x + x' terminal isocyanate groups;

[0095] R 6 and R 3 are the residues of cardanol after removing the hydroxyl H atoms and are bonded via an oxygen atom.

[0096] Cardanol (CAS Registry Number: 37330 - 39 - 5) is a phenolic lipid obtained from anacardic acid, which is the main component of cashew nut shell liquid (CNSL), a by - product of cashew processing. The name of this substance is derived from the abbreviation of the genus Anacardium, which includes the cashew tree Anacardium occidentale. The structure is shown in formula (X).

[0097]

[0098] R = C 15 H 31-n ; n = 0, 2, 4, 6

[0099] Cardanol refers to the decarboxylated derivatives obtained by thermal decomposition of any naturally occurring anacardic acid. This includes more than one compound as the composition of the side chain varies in terms of its degree of unsaturation. The tri - unsaturated cardanol, the main component (41%), is shown in the following formula (VI). The remaining cardanol is 34% monounsaturated, 22% di - unsaturated and 2% saturated.

[0100]

[0101] The phenolic OH group of cardanol readily reacts with the isocyanate groups of isocyanate - functional prepolymers to produce impact modifier I.

[0102] Notably and surprisingly, cardanol is the only phenolic reagent that can be used to produce impact modifier I of the present invention. Other similar phenolic reagents, especially nonylphenol, do not result in an impact modifier having the same beneficial properties as impact modifier I.

[0103] In addition, cardanol has the advantages of being based on natural, renewable resources and being inexpensive.

[0104] Cardanol can be commercially obtained, for example, under the trade name NC - 700 from Cardolite Corporation.

[0105] In the method for preparing a prepolymer end - capped with cardanol to prepare impact modifier I, at least one polymer diol is used. Suitable polymer diols are especially those mentioned above suitable for preparing polyurethane prepolymers.

[0106] Preferred diols are polyalkylene oxide diols, polyester diols, polycarbonate diols, polybutadiene diols and poly(meth)acrylate diols. Among them, polyether diols are particularly preferred, especially polypropylene glycol diol and polytetrahydrofuran diol.

[0107] Particularly preferred are polyoxypropylene glycols and polyoxyethylene-polyoxypropylene copolymer diols which are liquid especially at room temperature, in particular polyoxypropylene glycols having an average molecular weight of from 300 to 15,000 g / mol, especially from 1,000 to 10,000 g / mol, preferably from 2,000 to 5,500 g / mol. Particularly preferred are such diols having an average OH functionality of from 1.5 to 2.5, preferably from 1.8 to 2.3.

[0108] Further particularly preferred are diols which are liquid or solid, amorphous or semi-crystalline or crystalline at room temperature, especially polyester polyols and polycarbonate diols, especially polyester diols having an average molecular weight of from 300 to 15,000 g / mol, especially from 1,000 to 10,000 g / mol, preferably from 1,500 to 8,000 g / mol, especially from 2,000 to 5,500 g / mol. Particularly suitable are crystalline or semi-crystalline adipic acid / hexanediol polyesters and dodecanedioic acid / hexanediol polyesters.

[0109] Further particularly preferred are polybutadiene diols having an average OH functionality of from 1.5 to 2.5, preferably from 1.8 to 2.3, an average molar mass of from 300 to 15,000 g / mol, especially from 1,000 to 10,000 g / mol, preferably from 1,500 to 8,000 g / mol, more preferably from 2,000 to 4,000 g / mol, especially from 2,500 to 3,000 g / mol.

[0110] Such polybutadiene polyols can be obtained in particular by polymerizing 1,3-butadiene and allyl alcohol in a suitable ratio or by oxidizing a suitable polybutadiene.

[0111] Suitable polybutadiene polyols are in particular polybutadiene diols containing structural units of the formula (VII) and optionally structural units of the formulas (VIII) and (IX).

[0112]

[0113] Preferred polybutadiene diols contain

[0114] 40 to 80%, especially 55 to 65%, of the structural units of the formula (VII),

[0115] 0 to 30%, especially 15 to 25%, of the structural units of the formula (VIII),

[0116] 0 to 30%, especially 15 to 25%, of the structural units of the formula (IX).

[0117] Particularly suitable polybutadiene polyols are commercially available, for example, in the range of the trade name Poly from Cray Valley.

[0118] Most preferably among all the diols used for synthesizing the impact modifier I are polyoxypropylene diols and polyoxyethylene-polyoxypropylene copolymer diols which are liquid especially at room temperature, in particular polyoxypropylene diols having an average molecular weight of 300 - 15000 g / mol, especially 1000 - 10000 g / mol, preferably 2000 - 5500 g / mol. By using these diols, particularly high impact peel strength can be obtained.

[0119] Thus, in the most preferred embodiment, the diol is polyoxypropylene diol or polyoxyethylene-polyoxypropylene copolymer diol, in particular polyoxypropylene diol having an average molecular weight of 300 - 15000 g / mol, especially 1000 - 10000 g / mol, preferably 2000 - 5500 g / mol. Such diols are particularly preferably those having an average OH functionality of 1.5 - 2.5, preferably 1.8 - 2.3.

[0120] In the method for preparing a prepolymer capped with cardanol to produce the impact modifier I, at least one polyisocyanate, preferably a diisocyanate, is used.

[0121] Suitable polyisocyanates are especially monomeric di- or triisocyanates, as well as oligomers, polymers and derivatives of monomeric di- or triisocyanates, and any mixtures thereof. These polyisocyanates can be those as described above for preparing polyurethane prepolymers.

[0122] Suitable diisocyanates are especially commercially available aliphatic, cycloaliphatic, arylaliphatic and aromatic diisocyanates, preferably cycloaliphatic and aromatic diisocyanates.

[0123] Preferred diisocyanates are hexamethylene 1,6 - diisocyanate (HDI), 2,2,4 - and 2,4,4 - trimethylhexamethylene 1,6 - diisocyanate (TMDI), cyclohexane 1,3 - and 1,4 - diisocyanate and any desired mixtures of these isomers, 1 - isocyanato - 3,3,5 - trimethyl - 5 - isocyanatomethylcyclohexane ( = isophorone diisocyanate or IPDI), perhydrodiphenylmethane 2,4'- and 4,4'-diisocyanate (HMDI), meta - and para - xylylene diisocyanate (meta - and para - XDI), meta - and para - tetramethylxylylene 1,3 - and 1,4 - diisocyanate (meta - and para - TMXDI), toluene 2,4 - and 2,6 - diisocyanate (TDI) and any desired mixtures of these isomers, diphenylmethane 4,4'-, 2,4'- and 2,2'-diisocyanate, and any desired mixtures of these isomers (MDI).

[0124] More preferably, the diisocyanate is selected from HDI, IPDI, MDI and TDI. These diisocyanates are particularly easily obtainable.

[0125] Particularly preferred as the polyisocyanate, especially the diisocyanate, is the MDI form which is liquid at room temperature. These are in particular the so-called polymeric MDI and MDI having parts of oligomers or their derivatives. The content of this liquid form of MDI (=4,4′-, 2,4′- or 2,2′-diphenylmethane diisocyanate and any mixture of these isomers) is in particular 50 - 95% by weight, especially 60 - 90% by weight.

[0126] Particularly preferred as the polyisocyanate is polymeric MDI and MDI types which are preferably liquid at room temperature and contain parts of MDI - carbodiimide or its adducts.

[0127] The most preferred polyisocyanate for the synthesis of the impact modifier I is 4,4′-, 2,4′- and 2,2′-diphenylmethane diisocyanate and any mixture of these isomers (MDI), mixtures of MDI and MDI homologues (polymeric MDI or PMDI), especially in the form which is liquid at room temperature, and MDI having parts of oligomers or their derivatives. The content of this liquid form of MDI (=4,4′-, 2,4′- or 2,2′-diphenylmethane diisocyanate and any mixture of these isomers) is in particular 50 - 95% by weight, especially 60 - 90% by weight.

[0128] Thus, in the most preferred embodiment, the polyisocyanate is 4,4′-, 2,4′- or 2,2′-diphenylmethane diisocyanate and any mixture of these isomers (MDI). The impact modifier I based on MDI allows particularly high impact peel strength.

[0129] The impact modifier (I) preferably has an apparent epoxy equivalent of >500 g / eq, especially >1000 g / eq, preferably >1500 g / eq, especially >2000 g / eq.

[0130] It has been found advantageous that the content of the impact modifier (I) is 1 - 25% by weight, preferably 3 - 15% by weight, based on the total weight of the sealing composition. An impact modifier (I) of less than 1% by weight may weaken the elongation at break, while more than 25% by weight may weaken the tensile strength.

[0131] The polyaldehyde imine (PA) can be synthesized from a polyamine (PAM) having two or more primary amino groups and an aldehyde.

[0132] Suitable polyamines (PAM) having two or more primary amino groups particularly include:

[0133] - Aliphatic, cycloaliphatic or araliphatic diamines, such as ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 2-methyl-1,2-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1,3-butanediamine, 1,4-butanediamine, 1,3-pentanediamine (DAMP), 1,5-pentanediamine, 1,5-diamino-2-methylpentane (MPMD), 1,6-hexanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,2,4- and 2,4,4-trimethylhexanediamine (TMD), 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, and methyl-bis-(3-aminopropyl)amine, 1,2-, 1,3- and 1,4-diaminocyclohexane, bis-(4-aminocyclohexyl)methane, bis-(4-amino-3-methylcyclohexyl)methane, bis-(4-amino-3-ethylcyclohexyl)methane, bis-(4-amino-3,5-dimethylcyclohexyl)methane, bis-(4-amino-3-ethyl-5-methylcyclohexyl)methane (M-MECA), 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane (=isophoronediamine or IPDA), 2- and 4-methyl-1,3-diaminocyclohexane and mixtures thereof, 1,3- and 1,4-bis-(aminomethyl)cyclohexane, 2,5(2,6)-bis-(aminomethyl)bicyclo[2.2.1]heptane (NBDA), 3(4),8(9)-bis-(aminomethyl)tricyclo-[5.2.1.0 2,6 decane, 1,4-diamino-2,2,6-trimethylcyclohexane (TMCDA), 3,9-bis-(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane and 1,3- and 1,4-benzenedimethanediamine;

[0134] - Aliphatic diamines containing ether groups, such as bis(2-aminoethyl)ether, 3,6-dioxaoctane-1,8-diamine, 4,7-dioxadecane-1,10-diamine, 4,7-dioxadecane-2,9-diamine, 4,9-dioxadodecane-1,12-diamine, 5,8-dioxadodecane-3,10-diamine and higher oligomers of these diamines, bis-(3-aminopropyl)polytetrahydrofuran and other polytetrahydrofuran diamines with molecular weights in the range of for example 350 to 5200 and polyoxyalkylene diamines. The latter are usually products of the amination of polyoxyalkylene diols and can be obtained, for example, under the name (from Huntsman Chemicals), under the name polyetheramine (from BASF) or under the name PC (from Nitroil). Particularly suitable polyoxyalkylene diamines include D-230, D-400, D-2000, D-4000, XTJ-511, ED-600, ED-900, ED-2003, XTJ-568, XTJ-569, XTJ-523, XTJ-536, XTJ-542, XTJ-559, polyetheramine D230, polyetheramine D400 and polyetheramine D2000, PC DA 250, PC DA400, PC DA 650 and PC DA 2000;

[0135] - aliphatic triamines such as 4-aminomethyl-1,8-octanediamine, 1,3,5-tris(aminomethyl)benzene, 1,3,5-tris-(aminomethyl)cyclohexane;

[0136] - primary polyoxyalkylene triamines which are typically the amination products of polyoxyalkylene triols and which can be obtained, for example, under the trade name (from Huntsman Chemicals), under the name polyetheramine (from BASF) or under the name PC (from Nitroil), for example T-403, T-5000; polyetheramine T403, polyetheramine T5000; and PC TA 403, PC TA 5000.

[0137] Preferred polyamines (PAM) include polyamines selected from the group consisting of: 1,6-hexamethylenediamine, MPMD, DAMP, IPDA, TMD, 1,3-xylylenediamine, 1,3-bis(aminomethyl)cyclohexane, bis(4-aminocyclohexyl)methane, bis(4-amino-3-methyl-cyclohexyl)methane, 3(4),8(9)-bis(aminomethyl)tricyclo-[5.2.1.0 2,6Decane, 1,2-, 1,3- and 1,4-diaminocyclohexane, 1,4-diamino-2,2,6-trimethylcyclohexane, 3,6-dioxaoctane-1,8-diamine, 4,7-dioxadecane-1,10-diamine, 4-aminomethyl-1,8-octanediamine and polyoxyalkylene polyamines having two or three amino groups, in particular products D-230, D-400, D-2000, T-403 and T-5000 from Huntsman, which may be obtained under the brand name and similar compounds obtained from BASF or Nitroil and mixtures of the above polyamines. The above diamines are particularly preferred polyamines (PAM).

[0138] Basically any aldehyde is suitable as the aldehyde. These aldehydes can be aliphatic, cycloaliphatic, arylaliphatic or aromatic aldehydes and can be monoaldehydes or polyaldehydes.

[0139] It has been found that it is advantageous if the polyaldehydeimine (PA) does not have a hydrogen atom on the α-carbon atom of the carbon of the aldehyde imino group. Such aldehyde imines cannot form any tautomeric forms (enamines) - in contrast to aldehyde imines having a hydrogen atom on the α-carbon (see the following formula diagram):

[0140]

[0141] It has been found that compositions which are particularly stable in storage can be obtained using such polyaldehydeimines which do not have a hydrogen atom in the α-position.

[0142] Such polyaldehydeimines can be synthesized from polyamines (PAM) having two or more primary amino groups according to the said formula and aldehydes of the formula (II’) or (III’).

[0143]

[0144] wherein R1’ and R2’ each independently represent a monovalent hydrocarbon group having 1 to 12 carbon atoms, or R1’ and R2’ together represent a divalent hydrocarbon group having 4 to 12 carbon atoms, which is part of an optionally substituted carbocyclic ring having 5 to 8 carbon atoms, preferably 6 carbon atoms.

[0145] Furthermore, Z 1 represents a monovalent hydrocarbon group having 1 to 32 carbon atoms, optionally having at least one heteroatom, in particular oxygen in the form of an ether, carbonyl or ester group or in particular nitrogen in the form of a tertiary amino group.

[0146] Furthermore, Z 2 represents a substituted or unsubstituted aryl or heteroaryl having a ring size of 5 to 8 atoms, preferably 6 atoms, or represents

[0147] wherein R8 represents a hydrogen atom or an alkoxy group or a substituted or unsubstituted alkenyl or arylalkenyl group having at least 6 carbon atoms.

[0148] Examples of such aldehydes of formula (II') include aromatic aldehydes such as benzaldehyde, 2-, 3- and 4-tolualdehyde, 4-ethyl-, 4-propyl-, 4-isopropyl- and 4-butylbenzaldehyde, 2,4-dimethylbenzaldehyde, 2,4,5-trimethylbenzaldehyde, 4-acetoxybenzaldehyde, 4-methoxybenzaldehyde, 4-ethoxybenzaldehyde, isomeric di- and tri-alkoxybenzaldehydes, 2-, 3- and 4-nitrobenzaldehyde, 2-, 3- and 4-formylpyridine, 2-furaldehyde, 2-thiophenecarboxaldehyde, 1- and 2-naphthaldehyde, 3- and 4-phenoxybenzaldehyde, quinoline-2-carboxaldehyde and its 3-, 4-, 5-, 6-, 7- and 8-position isomers and anthracene-9-carboxaldehyde and glyoxal, glyoxylate esters such as methyl glyoxylate, cinnamaldehyde and substituted cinnamaldehydes.

[0149] Examples of aldehydes of formula (III’) include, for example, pivalaldehyde (=2,2-dimethylpropanal), 2,2-dimethylbutanal, 2,2-diethylbutanal, 1-methylcyclopentanecarboxaldehyde, 1-methylcyclohexanecarboxaldehyde, 2,2-dimethyl-3-phenylpropanal and 2,2-dimethyl-3-p-tolylpropanal; ethers of 2-hydroxy-2-methylpropanal and alcohols such as propanol, isopropanol, butanol and 2-ethylhexanol; esters of 2-formyl-2-methylpropanoic acid or 3-formyl-3-methylbutanoic acid and alcohols such as propanol, isopropanol, butanol and 2-ethylhexanol; esters of 2-hydroxy-2-methylpropanal and carboxylic acids such as butyric acid, isobutyric acid and 2-ethylhexanoic acid; and ethers and esters of 2,2-disubstituted 3-hydroxypropanal, butanal or similar higher aldehydes, in particular 2,2-dimethyl-3-hydroxypropanal, and aldehydes of formula (IV’) described below as being particularly suitable.

[0150] The polyaldehydeimines of formula (I’) have proven to be particularly suitable,

[0151]

[0152] wherein A’ represents the group of an amine after removal of n primary aliphatic amino groups, said group not containing any hydrogen atoms. Further, n represents 2 or 3 or 4 or 5, preferably 2 or 3. In addition, R1’ and R2’ each independently represent a monovalent hydrocarbon group having 1-12 carbon atoms, or R1’ and R2’ together represent a divalent hydrocarbon group having 4-12 carbon atoms, which is part of an optionally substituted carbocyclic ring having 5-8 carbon atoms, preferably 6 carbon atoms.

[0153] R3’ represents a hydrogen atom or an alkyl or aralkyl or alkoxycarbonyl group, in particular an alkyl or aralkyl or alkoxycarbonyl group having 1-12 carbon atoms.

[0154] R4’ and R5’ each independently represent a monovalent aliphatic, cycloaliphatic or araliphatic group having 1 to 20 carbon atoms, optionally containing a heteroatom in the form of an ether oxygen or a tertiary amine nitrogen, or R4’ and R5’ together represent a divalent aliphatic group having 3 to 20 carbon atoms, which is part of an optionally substituted heterocycle having 5 to 8 ring atoms, preferably 6 ring atoms, where the ring contains, in addition to a nitrogen atom, another heteroatom in the form of an ether oxygen or a tertiary amine nitrogen.

[0155] Furthermore, for the synthesis of the aldimine of formula (I’), at least one sterically hindered aliphatic aldehyde (ALD) of formula (IV’) is used:

[0156]

[0157] wherein R1', R2', R3', R4' and R5' have the meanings given above.

[0158] R1’ and R2’ each preferably represent a methyl group, and R3’ preferably represents a hydrogen atom.

[0159] R4’ and R5’ each preferably independently represent a methyl, ethyl, propyl, isopropyl, butyl, 2-ethylhexyl, cyclohexyl or benzyl group, or together - including the nitrogen atom - form a ring, in particular a pyrrolidine, piperidine, morpholine or N-alkylpiperazine ring, where the ring is optionally substituted.

[0160] The aldehyde (ALD) of formula (IV’) can in particular be obtained as the product of a Mannich reaction or an α-aminoalkylation analogous to the Mannich reaction, as is known from the technical literature, and can therefore also be referred to as a Mannich base. The aldehyde (Y1) of formula (V’), the aldehyde (Y2) of formula (VI’) and the aliphatic secondary amine (C) of formula (VII’) react herein, with the simultaneous removal of water, to form the aldehyde (ALD)

[0161]

[0162] wherein R1', R2', R3', R4' and R5' have the meanings given above.

[0163] The reaction can be carried out with free reagents, namely the aldehyde (Y1) of formula (V’), the aldehyde (Y2) of formula (VI’) and the amine (C), or these reagents can be used in partially or fully derivatized form. Thus, the aldehyde (Y1) can be used as an enolate, as an enol ether, in particular as a silylenol ether or as an enamine. For example, the aldehyde (Y2) can be used in the form of an oligomer - in particular as 1,3,5 - trioxane or as paraformaldehyde in the case of formaldehyde - or as a hydrate, hemiacetal, acetal, N,O - acetal, acetalamine or hemiacetalamine. Finally, the aliphatic secondary amine (C) can be used in the form of a salt, in particular as an amine hydrochloride or as an amine hydrogensulfate or as a silylamine. It is possible to use a part of the reagents in free form and a part in derivatized form or to use them only in derivatized form. When using derivatized reagents, the aldehyde (ALD) is also obtained in derivatized form, for example as a salt in certain cases. In this case, it can be converted to the free form according to formula (IV’) by suitable post - treatment. In such a conversion reaction, it may be appropriate to additionally use additives such as Lewis acids or catalysts depending on the conditions.

[0164] Furthermore, the reaction can be carried out as a one - pot reaction in which all three reagents can react with each other simultaneously; or a step - by - step reaction procedure can be chosen by reacting the first two reagents with each other and then reacting the resulting intermediate with the third reagent, where the intermediate can or cannot be isolated. Such suitable intermediates particularly include iminium salts, which are obtained by reacting the aldehyde (Y2) in free or derivatized form with the salt of the aliphatic secondary amine (C), and which can react with the aldehyde (Y1) in free or derivatized form to form the corresponding salt of the aldehyde (ALD) of formula (IV’). Such a step - by - step procedure may be advantageous in allowing milder reaction conditions and thus higher product yields.

[0165] Furthermore, the reaction can be carried out using a solvent, in particular a polar solvent such as water or an alcohol, or the reaction can be carried out without using a solvent.

[0166] In a preferred embodiment, the reaction is carried out in the form of a one - pot reaction with all reagents in free form, and after completion of the reaction, the aldehyde (ALD) is purified by distillation. Preferably, no organic solvents are used.

[0167] For example, the following aldehydes are suitable as the aldehyde (Y1) of formula (V’): isobutyraldehyde, 2 - methylbutyraldehyde, 2 - ethylbutyraldehyde, 2 - methylvaleraldehyde, 2 - ethylhexanal, cyclopentanecarbaldehyde, cyclohexanecarbaldehyde, 1,2,3,6 - tetrahydrobenzaldehyde, 2 - methyl - 3 - phenylpropanal, 2 - phenylpropanal and diphenylacetaldehyde. Isobutyraldehyde is preferred.

[0168] Suitable examples of the aldehyde (Y2) of formula (VI’) include the following aldehydes: formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, isobutyraldehyde, phenylacetaldehyde, benzaldehyde and substituted benzaldehydes, and glyoxylate esters, especially ethyl glyoxylate. Formaldehyde is preferred.

[0169] Examples of suitable amines (C) of formula (VII’) include the following aliphatic secondary amines: dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine, diisobutylamine, di-sec-butylamine, dihexylamine, di(2-ethylhexyl)amine, dicyclohexylamine, N-methylbutylamine, N-ethylbutylamine, N-methylcyclohexylamine, N-ethylcyclohexylamine, di-2-methoxyethylamine, pyrrolidine, piperidine, N-methylbenzylamine, N-isopropylbenzylamine, N-tert-butylbenzylamine, dibenzylamine, morpholine, 2,6-dimethylmorpholine, bis-(3-dimethylaminopropyl)amine, N-methyl or N-ethylpiperazine.

[0170] Preferred examples of the amine (C) include dimethylamine, diethylamine, diisopropylamine, dibutylamine, diisobutylamine, N-methyl-cyclohexylamine, N-methylbenzylamine, N-isopropylbenzylamine, N-tert-butyl-benzylamine, dibenzylamine, pyrrolidine, piperidine, morpholine, 2,6-dimethylmorpholine, N-methyl- and N-ethylpiperazine.

[0171] The aldehyde (ALD) is preferably synthesized by reacting isobutyraldehyde as the aldehyde (Y1) of formula (V’), formaldehyde as the aldehyde (Y2) of formula (VI’), and an amine selected from dimethylamine, diethylamine, diisopropylamine, dibutylamine, diisobutylamine, N-methylcyclohexylamine, N-methylbenzylamine, N-isopropylbenzylamine, N-tert-butylbenzylamine, dibenzylamine, pyrrolidine, piperidine, morpholine, 2,6-dimethylmorpholine, N-methyl- and N-ethyl-piperazine as the amine (C) of formula (VII’).

[0172] Preferred aldehydes (ALD) include 2,2-dimethyl-3-dimethylaminopropionaldehyde, 2,2-dimethyl-3-diethylaminopropionaldehyde, 2,2-dimethyl-3-dibutyl-aminopropionaldehyde, 2,2-dimethyl-3-(N-pyrrolidinyl)propionaldehyde, 2,2-dimethyl-3-(N-piperidinyl)propionaldehyde, 2,2-dimethyl-3-(N-morpholinyl)propionaldehyde, 2,2-dimethyl-3-(N-(2,6-dimethyl)morpholinyl)propionaldehyde, 2,2-dimethyl-3-(N-(4-methylpiperazinyl))propionaldehyde, 2,2-dimethyl-3-(N-(4-ethylpiperazinyl))propionaldehyde, 2,2-dimethyl-3-(N-benzylmethyl-amino)propionaldehyde, 2,2-dimethyl-3-(N-benzylisopropylamino)propionaldehyde and 2,2-dimethyl-3-(N-cyclohexylmethylamino)propionaldehyde. The preferred aldehyde (ALD) has a relatively low basicity.

[0173] The aldimines of formula (I’) can be directly synthesized from a polyamine (PAM) having two or more primary amino groups and an aldehyde (ALD) of formula (IV’), as described above, by reacting the polyamine (PAM) with the aldehyde (ALD) in a condensation reaction to remove water.

[0174] It has been found that improved storage stability of the thermosetting sealant composition can be achieved when using the polyaldimine of formula (I’).

[0175] In a preferred embodiment, the polyaldimine (PA) can be a dialdimine of formula (XI)

[0176]

[0177] wherein R represents the group of the aldehyde ALD after removal of the aldehyde group;

[0178] A represents the group of a diamine DA having two aliphatic primary amino groups after removal of the two aliphatic primary amino groups;

[0179] Q represents the group of a diisocyanate DI after removal of the two isocyanate groups; z represents 0 or an integer from 1 to 15; and

[0180] wherein A and R do not have groups that can react with the isocyanate group in the absence of water.

[0181] For more details on the preparation and application of the diamine of formula (XI), reference can be made to CN101616891A, the entire content of which is incorporated into this specification.

[0182] Based on the weight of the thermosetting sealant composition, the polyaldimine (PA) is usually used in an amount of 0.3 wt% to 10 wt%, particularly 0.5 wt% to 5 wt%, preferably 1 wt% to 3 wt%.

[0183] Furthermore, the polyaldimine (PA) is preferably present in the sealant composition in an amount such that the ratio of the number of aldimino groups to the number of isocyanate groups has a value of 0.2 to 0.8, particularly 0.3 to 0.7.

[0184] The sealant composition of the present invention described herein may contain additional components as needed. In particular, these include fillers (F), reactive diluents, catalysts, stabilizers, particularly heat and / or light stabilizers, thixotropic agents, plasticizers, solvents, blowing agents, dyes and pigments, corrosion inhibitors, surfactants, foam inhibitors, and adhesion promoters.

[0185] The filler (F) is preferably mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (chalk, precipitated or ground), dolomite, quartz, silicic acid (pyrogenic or precipitated), cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, ceramic hollow beads, glass hollow beads, organic hollow beads, glass beads, carbon black, graphite, metal powder, ground conductive polymer or colored pigment.

[0186] Particularly preferably, the sealing composition contains carbon black or other conductive additives, especially graphite, metal powder or ground conductive polymer as the filler. These result in the sealing compound composition having a certain electrical conductivity during the coating with the CDC coating, which in turn has a favorable effect on the coating result.

[0187] Suitable fillers (F) include both organically coated and uncoated forms, which are commercially available and known to those skilled in the art.

[0188] The total amount of the total filler (F) is preferably 3 - 50% by weight, especially 5 - 35% by weight, particularly 5 - 25% by weight, based on the weight of the total composition.

[0189] In a preferred embodiment, the sealing composition further contains a reactive diluent, which may be a reactive diluent (G) containing epoxy groups.

[0190] Reactive diluents (G) containing epoxy groups particularly include:

[0191] - Monofunctional saturated or unsaturated branched or unbranched cyclic or acyclic C4 to C 30 glycidyl ethers of alcohols, especially selected from butyl glycidyl ether, hexyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, tetrahydrofurfuryl and furfuryl glycidyl ether, trimethoxysilyl glycidyl ether.

[0192] - Bifunctional saturated or unsaturated branched or unbranched cyclic or acyclic C2 to C 30 glycidyl ethers of alcohols, especially selected from ethylene glycol, butanediol, hexanediol, octanediol glycidyl ether, cyclohexanedimethanol diglycidyl ether and neopentyl glycol diglycidyl ether.

[0193] - Trifunctional or polyfunctional saturated or unsaturated branched or unbranched cyclic or acyclic glycidyl ethers of alcohols, such as epoxidized castor oil, epoxidized trimethylolpropane, epoxidized pentaerythritol or polyglycidyl ethers of aliphatic polyols such as sorbitol, glycerol or trimethylolpropane.

[0194] - Glycidyl ethers of phenol and aniline compounds, especially phenyl glycidyl ether, tolyl glycidyl ether, p-tert-butylphenyl glycidyl ether, nonylphenol glycidyl ether, 3-n-pentadecenyl glycidyl ether (from cashew nut shell oil), N,N-diglycidylaniline, and triglycidyl p-aminophenol.

[0195] - Epoxidized amines, such as N,N-diglycidyl cyclohexylamine.

[0196] - Epoxidized monocarboxylic or dicarboxylic acids, especially glycidyl neodecanoate, glycidyl methacrylate, glycidyl benzoate, phthalic acid, diglycidyl tetrahydrophthalate, diglycidyl hexahydrophthalate, diglycidyl ester of dimer fatty acid, and glycidyl terephthalate and glycidyl trimellitate;

[0197] - Epoxidized difunctional or trifunctional low to high molecular weight polyether polyols, especially polyethylene glycol diglycidyl ether or polypropylene glycol diglycidyl ether.

[0198] Hexanediol diglycidyl ether, tolyl glycidyl ether, p-tert-butylphenyl glycidyl ether, polypropylene glycol diglycidyl ether, and polyethylene glycol diglycidyl ether are particularly preferred.

[0199] The total amount of the reactive diluent (G) containing epoxy groups is advantageously 0.1 - 20% by weight, preferably 1 - 8% by weight, based on the weight of the total composition.

[0200] In another particularly preferred embodiment, the sealing composition further contains at least one catalyst (KA) that accelerates the hydrolysis of the aldehyde imino group. Such catalysts (KA) particularly include acids, such as organic carboxylic acids like benzoic acid, salicylic acid, or 2-nitrobenzoic acid, organic carboxylic anhydrides like phthalic anhydride, hexahydrophthalic anhydride, and hexamethylhexahydrophthalic anhydride, silyl esters of organic carboxylic acids, organic sulfonic acids like methanesulfonic acid, p-toluenesulfonic acid, or 4-dodecylbenzenesulfonic acid, sulfonic acid esters, other organic or inorganic acids, or mixtures of the above acids and acid esters. Salicylic acid or 2-nitrobenzoic acid is most preferably used as the catalyst (KA).

[0201] Furthermore, it is particularly advantageous if the sealing composition further contains at least one catalyst (KN) that accelerates the reaction of the isocyanate group. Such catalysts (KN) that accelerate the reaction of the isocyanate group particularly include organotin compounds, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, dibutyltin diacetylacetonate, and dioctyltin dilaurate, bismuth compounds like bismuth trioctoate and bismuth trineodecanoate, and compounds containing a tertiary amino group, such as 2,2'-dimorpholinodiethyl ether and 1,4-diazabicyclo[2.2.2]octane.

[0202] Furthermore, it is particularly advantageous if the sealing composition additionally contains at least one rheology modifier (R). Such rheology modifiers (R) particularly include thickeners or thixotropic agents, such as urea compounds, polyamide waxes, bentonites or pyrogenic silicas.

[0203] The sealing composition according to the invention preferably consists essentially, i.e. in particular more than 95% by weight, of the following:

[0204] - at least one epoxy-terminated polyurethane prepolymer (A);

[0205] - a heat-activatable curing agent or accelerator (B), which comprises an amidoamine having a primary amino group and dicyandiamide;

[0206] - an impact modifier (I), which is a reaction product of at least one polymer diol, at least one polyisocyanate and cardanol;

[0207] - at least one polyaldehyde imine (PA);

[0208] - optional filler (F);

[0209] - a reactive diluent (G) containing an epoxy group;

[0210] - optional plasticizer;

[0211] - optional catalyst (KA), which accelerates the hydrolysis of the aldehyde imino group;

[0212] - optional catalyst (KN), which accelerates the reaction of the isocyanate group; and

[0213] - optional rheology modifier (R).

[0214] It goes without saying that in the polyurethane prepolymer (A) according to the invention, the heat-activatable curing agent or accelerator (B), the impact modifier (I), the polyaldehyde imine (PA), the filler (F), the reactive diluent (G) containing an epoxy group, the plasticizer, the catalyst (KA), the catalyst (KN) and the rheology modifier (R) are each different substances.

[0215] The sealing composition is prepared and stored in the absence of moisture. It is stable in storage, i.e. it can be stored in a suitable packaging or configuration (e.g. drum, bag or cartridge) in the absence of moisture for several months or up to one year or even longer without any change in its application properties or cured properties to an extent relevant to its use. Storage stability is usually determined by measuring the viscosity.

[0216] The sealing composition is characterized by very good storage stability. After storage in a circulating air oven at 60 °C for 5 days, the viscosity change of the sealing compound in an airtight aluminum cartridge can be used as a measure of long-term storage stability at room temperature. Experience has shown that for reliable use of the composition as a sealing compound, a viscosity increase of up to twice, i.e., a maximum of 100%, is allowed. It has been found that the sealing composition excellently meets this requirement; a viscosity change of less than 55% in total and even less than 35% in some cases can be achieved.

[0217] The sealing composition according to the invention forms few or no air bubbles during curing. Air bubbles usually form during the air curing of polyisocyanates. Therefore, they have excellent mechanical properties and an optimal visual appearance. This is particularly important since the CDC coating is above the surface of the sealing compound, and thus the surface of the sealing compound can be seen through the CDC coating and / or a colored coating subsequently placed thereon.

[0218] Furthermore, the sealing composition has great elasticity after heat curing and can have very good impact strength. This is particularly advantageous in cases where the seal is subjected to impacts or movements during use.

[0219] This combination of advantageous properties enables the sealing composition to be used particularly as a sealing compound in automotive bodywork, especially in the engine compartment or for doors, trunk lids, tailgates or hoods. In particular, they can also be used as a sealing compound in flange-fold seals, such as those disclosed in WO 2008 / 077918 A1.

[0220] In another aspect of the invention, a method for sealing is disclosed, which comprises the following steps:

[0221] i) applying a sealing composition as described above, for example, to a substrate (S) such that a part of the surface of the sealing composition is in contact with air;

[0222] ii) forming a skin on the surface of the sealing composition in contact with air;

[0223] iii) heating the sealing composition to a temperature above 120 °C, especially 160 °C to 220 °C, to form a cured sealing composition.

[0224] Materials suitable for the substrate (S) particularly include metals, especially those used for constructing automotive bodies. These particularly include steels, especially electrolytically galvanized, flame galvanized, oiled steels, steels plated with Bonazinc and subsequently phosphated, or aluminum, especially in the variants commonly found in automotive engineering. These particularly include steel sheets or aluminum sheets.

[0225] Application, i.e., deposition, is preferably carried out automatically, especially in the form of a strip. However, it is also possible to spray the sealant compound composition. Other application methods are also conceivable, such as spin coating, laminar spraying, micro-laminar spraying, and fine stream spraying at a speed of >200 mm / s. In addition, the applied sealant compound composition can also be manually applied or reworked by a spatula or a paintbrush.

[0226] Thus, in another aspect, the present invention also relates to a coated substrate obtained by applying a sealant composition, such as described in detail above, to the surface of a substrate.

[0227] In a particularly preferred embodiment, the sealant compound composition is applied to an oiled steel sheet. The advantage of this composition is that it adheres well to such a substrate and cures with few blisters.

[0228] Step iia) is preferably carried out between step ii) and step iii):

[0229] iia) Applying a coating, especially a CDC coating, to the sealant composition.

[0230] Those skilled in the art of automotive engineering are very familiar with the concept of CDC paint, which refers to the paint applied to a metal sheet in a CDC bath (CDC = cathodic dip coating).

[0231] Step iii) is preferably carried out in a CDC oven.

[0232] By heating the sealant composition, further curing occurs, enabling the sealant composition to obtain its final strength.

[0233] The sealant composition is particularly suitable for sealing gaps.

[0234] Therefore, in step i), it is preferred to apply the sealant composition in or to a gap defined by two surfaces of a substrate (S) and a second substrate (S2), where the second substrate (S2) is made of the same material or a different material from the substrate (S).

[0235] Thus, a sealed article is obtained by the above method. Examples

[0236] The examples given below are only for illustrating the present invention.

[0237] Table 1 lists the raw materials used.

[0238]

[0239] Table 1. Raw materials used

[0240] Another part of the raw materials for synthesis are as follows:

[0241]

[0242] Table 2. Some raw materials for synthesis

[0243] Synthesis of prepolymer A

[0244] 417.5 g of Poly R-45HTLO and 154.2 g of DGEBA were stirred under vacuum at 80 °C together with 328.6 g of diisodecyl phthalate (DIDP). 0.8 g of a catalyst solution (10 wt% dibutyltin dilaurate (DBTDL) in diisononyl phthalate) was added. Subsequently, 98.9 g of IPDI was added with stirring and the mixture was stirred at 80 °C for 2 hours. The resulting premix of polyurethane polymer and epoxy resin had an NCO content of 1.6 wt% and an epoxy content of 0.82 molEq / kg.

[0245] Synthesis of impact modifier I

[0246] Make a 1:1 (by weight) mixture of 2000 (BASF) and R-45HTLO react with IPDI (2 equivalents relative to the OH functionality of the polyol), and then the isocyanate groups of the polymer thus obtained are blocked with cardanol (trade name NC-700 (Cardolite)). The reaction is stopped once no free isocyanate is detected anymore by IR spectroscopy (wave numbers 2275 - 2230 cm-1).

[0247] Synthesis of polyaldehyde imine PA

[0248] 14.55 g of IPDA was added to a round-bottom flask under a nitrogen atmosphere. While stirring vigorously, 30.00 g of 2,2-dimethyl-3-(N-morpholino)propanal was added from a dropping funnel. Then the volatile components were removed under vacuum (10 mbar, 80 °C). 40.9 g of a transparent colorless oil was obtained with an amine content of 8.29 mmolN / g.

[0249] Preparation of sealing composition

[0250] Using the ingredients expressed in parts by weight in Table 2, various sealing compositions were prepared in the absence of moisture. At room temperature, with stirring at a speed of 200 - 300 rpm / min, all the ingredients were put into a vacuum mixer in three batches. The epoxy - terminated polyurethane and the impact modifier were put into the first batch, then the powdery materials were put into the second batch, and finally the curing agent and the liquid were added. Keep the temperature not exceeding 50 °C, and stir for 40 - 50 minutes while introducing nitrogen to break the vacuum.

[0251] After preparation, the composition was left for 24 hours and then directly used for testing. The mixture was cured at 180 °C for 30 minutes.

[0252] Measurement method

[0253] The following properties of the composition were measured:

[0254] Elongation at break and tensile strength

[0255] The elongation at break and tensile strength were measured mainly based on ISO 37 and ISO 527 - 2. Samples were prepared by making bubble - free sheets of the sealant with a thickness of 2 mm (±0.5 mm). They were cured and then stored at 23 °C / 50% RH for 2 - 6 hours. Then at least 5 dumbbells according to ISO 37 Type 2 / ISO 527 - 2 Type 5A (Chapter 6) were punched out from the sheets. They were tested and the result was the average of at least 5 measurements.

[0256] Viscosity

[0257] To measure the viscosity of the composition, an Anton Paar rheometer MCR102 was used while the temperature was increased from 20 °C to 70 °C at a rate of 10 K / min. The sample was measured at 23 °C (or 50 °C) with a gap size of 1 mm and a shear stress of 10 s -1 .

[0258] Skin formation

[0259] To determine the skin formation time ("SFT"), the composition was applied to cardboard at room temperature with a layer thickness of about 3 mm, and the time when there was no residue of the composition remaining on the pipette for the first time when the surface of the composition was tapped gently with a pipette made of LDPE was determined in standard atmospheric pressure (STP; 23 ± 1 °C, 50 ± 5% relative humidity).

[0260] Extrusion force

[0261] To determine the extrusion force, the composition was dispensed into an internally coated aluminum cartridge (outer diameter 46.9 mm, inner diameter 46.2 mm, length 215 mm, metric ISO thread M15×1.5 mm) and hermetically sealed with a polyethylene stopper (diameter 46.1 mm) from Novelis Deutschland GmbH. After conditioning at 23 °C for 24 hours, the cartridge was opened and the contents were extruded using an extrusion device. For this purpose, a nozzle with a 5 mm inner diameter opening was screwed onto the barrel thread. Using an extrusion device (Zwick / Roell Z005), the force required to extrude the composition at an extrusion rate of 60 mm / min was determined. The reported numbers are the average of the forces measured after extrusion distances of 22 mm, 24 mm, 26 mm, and 28 mm. Measurement was stopped after an extrusion distance of 30 mm.

[0262] Bubbling (bubbles in the tape)

[0263] The triangular tapes of the composition were applied to metal tiles to prepare samples. After storage at room temperature for one day, they were then placed in a convection oven at an elevated temperature of 180 °C for 30 minutes to cure thoroughly. The samples were placed under exhaust conditions. Then the tape was cut parallel to the substrate in the application direction using a cutter. Visual inspection was carried out to check if bubbles were visible. "None" means that no visible bubbles were present.

[0264] Lap shear strength

[0265] The 2 mm lap shear strength was measured on an oiled hot-dip galvanized steel sheet according to ISO 4587. Using the composition of the present invention, 100% CF (cohesive failure) was achieved on the substrate.

[0266] Sagging resistance

[0267] A piece of cardboard was placed in a completely upright position. A 15 cm long triangular tape with dimensions of 8 mm×10 mm was carefully applied to the cardboard and held in that position for at least 2 - 3 minutes. Then its appearance was rated according to the following grades:

[0268] 1 - Excellent Tip does not move 2 - Good Tip is between the center and the base axis 3 - Fair Height of the tip on the base axis 4 - Poor Tip is lower than the base axis 5 - Bad No tip

[0269]

Claims

1. A sealing composition, comprising: - at least one epoxy - terminated polyurethane prepolymer (A); - a heat - activatable curing agent or accelerator (B), which comprises an amidoamine having a primary amino group and dicyandiamide; - an impact modifier (I), which is a reaction product of at least one polymeric diol, at least one polyisocyanate and cardanol; and - at least one polyaldehyde imine (PA).

2. The sealing composition according to claim 1, characterized in that The epoxy - terminated polyurethane prepolymer (A) is a polyurethane prepolymer containing isocyanate groups, which is partially terminated by epoxides and has a certain content of free isocyanate groups, preferably 0.8 - 3.0 wt%, preferably 1.0 - 2.5 wt%, more preferably 1.5 - 2.0 wt% of free NCO groups, based on the total weight of the polyurethane prepolymer (A).

3. The sealing composition according to claim 1 or 2, characterized in that, The epoxy - terminated polyurethane prepolymer (A) is represented by the following formula (IVa): where R 1 is a linear or branched polyurethane prepolymer PU1 capped with n + m isocyanate groups after removal of all terminal isocyanate groups; Each R 2 is independently a group of formula (II) wherein in each case, R 4 is the moiety of an aliphatic, alicyclic, aromatic or araliphatic epoxide containing a primary or secondary hydroxyl group after removal of hydroxide and epoxide groups; p = 1, 2 or 3; n and m are each values from 1 to 7, provided that 2 ≤ (m + n) ≤ 8.

4. The sealing composition according to any one of the preceding claims, characterized in that, The polyaldehyde imine (PA) is present in the sealing compound composition in an amount such that the ratio of the number of aldehyde imino groups to the number of isocyanate groups has a value of 0.2 to 0.8, especially 0.3 to 0.

7.

5. The sealing composition according to any one of the preceding claims, characterized in that, The heat - activatable curing agent or accelerator (B) comprises 1.0 - 3.3% by weight, preferably 1.5 - 3.0% by weight of an amidoamine having a primary amino group and 0.05 - 0.8% by weight, preferably 0.12 - 0.55% by weight of dicyandiamide, each based on the total weight of the sealing composition.

6. The sealing composition according to any one of the preceding claims, characterized in that The amidoamine having a primary amino group is an amidoamine obtained by the reaction of phthalic anhydride and a polyamine having a primary amino group, especially diethylenetriamine (DETA) or triethylenetetramine (TETA).

7. The sealing composition according to any one of the preceding claims, characterized in that The content of the impact modifier (I) is 1 - 25% by weight, preferably 3 - 15% by weight, based on the total weight of the sealing composition.

8. A sealing composition according to any of the preceding claims, characterized in that The impact modifier I is a polymer of formula (IV), wherein x and x' are each independently 0 or 1, preferably 1, provided that at least one, preferably both of n and n' are not 0; R 5 is a linear polyurethane prepolymer containing at least x + x' terminal isocyanate groups after removing x + x' terminal isocyanate groups; R 6 and R 3 are the residues of cardanol after removing the hydroxyl H atoms and are bonded by oxygen atoms.

9. The sealing composition according to any one of the preceding claims, characterized in that The sealing composition further contains carbon black or other conductive additives, especially graphite, metal powder or ground conductive polymer as fillers.

10. A coated substrate, obtained by applying the sealing composition according to any one of claims 1 to 9 to the surface of a substrate.

11. A method for sealing, comprising the following steps: i) applying the sealing composition according to any one of claims 1 to 9 to a substrate (S) such that a part of the surface of the sealing compound composition is in contact with air; ii) forming a skin on the surface of the sealing composition in contact with air; iii) heating the sealing compound composition to a temperature higher than 120°C, especially between 160°C and 220°C, to form a fully cured sealing composition.

12. The method for sealing according to claim 11, characterized in that, Step iia) is carried out between steps ii) and iii): iia) applying a coating, especially a CDC coating, to the sealing composition.

13. The method according to claim 11 or 12, characterized in that, Step iii) is carried out in a CDC oven.

14. The method according to claim 11 or 12 or 13, characterized in that Apply the sealing composition in step i) to or into the gap defined by two surfaces of a substrate (S) and a second substrate (S2), the second substrate (S2) being made of the same material or a different material than the substrate (S).

15. A sealed article obtained by the method according to any one of claims 11 to 14.

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