EP2059559A1

EP2059559A1 - Adhesive or sealant with modified inorganic particles

Info

Publication number: EP2059559A1
Application number: EP07802377A
Authority: EP
Inventors: Winfried Wichelhaus; Rainer SCHÖNFELD; Stefan Kreiling
Original assignee: Henkel AG and Co KGaA
Current assignee: Henkel AG and Co KGaA
Priority date: 2006-09-08
Filing date: 2007-07-16
Publication date: 2009-05-20
Also published as: DE102006042796A1; WO2008028719A1

Abstract

Epoxide-based adhesive or sealant containing, based on the overall adhesive, 5% to 30% by weight of inorganic particles whose surface has been coated by reaction with organic molecules which carry at least two terminal functional groups, each functional group containing at least one heteroatom having at least one free electron pair.

Description

"Adhesive or sealant with modified inorganic particles"

The present invention relates to an epoxy-based adhesive or sealant containing, based on the total adhesive, from 5 to 30% by weight of inorganic particles whose surface has been coated by reaction with organic molecules carrying at least two terminal functional groups each functional group contains at least one heteroatom with at least one free electron pair. This addition improves important performance properties, in particular the peel strength at low temperatures. A special field of application is the use as structural adhesive in vehicle construction.

Reactive epoxy-based hot melt adhesives are known. In machine, vehicle or equipment construction, in particular in aircraft construction, rail vehicle construction or motor vehicle construction, the components made of the various metallic components and / or composite materials are increasingly joined with the aid of adhesives. For structural bonds with high strength requirements, epoxy adhesives are used extensively, in particular as hot-curing, one-component adhesives, which are often also formulated as reactive hot melt adhesives. Reactive hot melt adhesives are adhesives that are solid at room temperature and soften at temperatures up to about 80 to 90 ⁰ C and behave like a thermoplastic material. Only at higher temperatures from about 100 ⁰ C present in these hot melt adhesives latent curing agents are thermally activated, so that irreversible curing takes place to a thermoset. For joining the components, for. As in the automotive industry, the adhesive is first applied warm to at least one substrate surface, the components to be joined are then joined. Upon cooling, the adhesive then solidifies and provides by this physical solidification sufficient handling strength, ie, a preliminary connection. The such interconnected components are further treated in the various washing, phosphating and dip coating baths. Only then is the adhesive cured in an oven at higher temperatures.

Conventional adhesives and hot melt adhesives based on epoxy resins are hard and brittle in the cured state. Although the bonds obtained with you usually have a very high tensile shear strength. In peeling, beating or impact peeling stress, in particular at lower temperatures, but this burst, so that it comes easily to bond loss in this type of stress of the adhesive joint. There have therefore been numerous proposals to modify epoxy resins by flexible additives so that their brittleness is significantly reduced. A common method is based on the use of special rubber adducts of epoxy resins, which are incorporated as a heterodisperse phase in the epoxy resin matrix, so that the epoxies are impact-resistant, these epoxy resin compositions are also referred to as "toughened". A common, known modification of epoxy resins of the aforementioned type consists in the reaction of a polybutadiene-co-acrylonitrile copolymer having carboxyl end groups with an epoxy resin. This rubber-epoxy adduct is then dispersed in one or more different epoxy resins. The reaction of the epoxy resin with the carboxy-containing butadiene-acrylonitrile rubber must be conducted in such a way that it does not lead to premature curing of the adduct. Although such modified epoxy resin compositions already present a significant improvement in their impact resistance over the unmodified epoxy resins, their behavior towards peeling loads is still insufficient.

WO 01/94492 is to improve reactive adhesives of the type mentioned at the outset further that they have sufficient flexibility, increased peel strength have not only at room temperature but in particular also at low temperatures below 0 ⁰ C, the task. In particular, the peel strength at low temperatures and sudden load a have the highest possible value, so that structurally bonded components in the event of an accident (crash behavior) meet the modern safety requirements in vehicle construction. These improvements should be achieved without affecting the peel strength and tensile shear strength at high temperatures. In addition, the reactive adhesives must have sufficient leaching resistance immediately after application and before final curing. For this purpose, the adhesive compositions must be formulated as a hot melt adhesive or as a highly viscous, warm adhesive to be processed. Another possibility is the formulation as an adhesive, which can be gelled by a thermal pre-reaction in the so-called "shell furnace" or by induction heating of the parts to be joined.

This document WO 01/94492 achieves this object by providing compositions containing the following components:

A) at least one epoxy resin having on average more than one epoxide group per molecule

B) a copolymer having a glass transition temperature of -30 ⁰ C or lower, and epoxide-reactive groups or a reaction product of this copolymer with a stoichiometric excess of an epoxy resin according to A)

C) a latent, activatable at elevated temperature, hardener for component A), and either

D) a reaction product preparable from a difunctional amino-terminated polymer and a tri- or tetracarboxylic anhydride, characterized by an average of more than one imide group and carboxyl group per molecule, or

E) a reaction product preparable from a tri- or polyfunctional polyol or a tri- or polyfunctional amino-terminated polymer and a cyclic carboxylic anhydride, wherein the reaction product contains on average more than one carboxyl group per molecule, or

F) a mixture of the reaction products according to D) and E). Furthermore, this document teaches that said adhesives known per se

Fillers may contain, such as the various milled or precipitated chalks, carbon black, calcium magnesium carbonates, heavy spar and in particular silicatic fillers of the type of aluminum-magnesium-calcium silicate, z. B. wollastonite, chlorite.

As explained in the cited WO document, the requirements for modern structural adhesives in vehicle construction are constantly increasing, since more and more structural elements are also joined to the load-bearing nature by adhesive bonding methods. Therefore, the adhesives must meet a practice-relevant aspects of manufacturing, this includes automated processing in short cycle times, adhesion to oiled sheets, adhesion to various types of sheet and compatibility with the process conditions of the paint line (resistance to washing and phosphating, curable during the stoving of the cathodic Primer, resistance to subsequent painting and drying operations). In addition, modern structural adhesives must also meet increasing strength and deformation properties in the cured state. These include the high corrosion resistance or bending stiffness of the structural components as well as the deformability under mechanical stress of the bond. The highest possible deformability of the components ensures a considerable safety advantage in case of impact load (crash behavior) in an accident. This behavior can be best achieved by determining the impact energy for cured bonds determine this are desirable both at high temperatures of up to +90 ⁰ C and in particular at low temperatures down to -40 ⁰ C sufficiently high values for impact energy or impact peel or required. In addition, the highest possible tensile shear strength should be achieved. Both strengths have on a variety of substrates, mainly oiled sheets, such. As body steel sheet, galvanized sheet steel, sheets of various aluminum alloys or magnesium alloys and with organic coatings of the type "Bonazinc" or "Granocoat" in the coil coating-coated steel sheets can be achieved by a variety of methods. The object of the present invention is to provide epoxy-based adhesives or sealants which, at least in some of the above-mentioned requirements, lead to improvements.

The present invention relates to an epoxy-based adhesive or sealant containing, based on the total adhesive, from 5 to 30% by weight of inorganic particles whose surface has been coated by reaction with organic molecules carrying at least two terminal functional groups each functional group contains at least one heteroatom with at least one lone pair of electrons.

With a content of less than 5 wt .-% of inorganic particles, the reinforcing effect decreases increasingly. The upper limit of the content of inorganic particles depends on the viscosity of the adhesive or sealant at the processing temperature. The viscosity increases with increasing content of inorganic particles. However, it must not become so high that the adhesive or sealant is no longer flowable at the intended application temperature. An upper limit of 30% by weight of inorganic particles is a guideline value which can be exceeded if appropriate with particularly low-viscosity adhesives or sealants. An upper limit of 20% by weight of inorganic particles generally still results in a suitable viscosity at the application temperature in the case of industrially customary epoxy-based adhesives or sealants and is therefore preferred as upper limit.

The use of inorganic particles as fillers and / or reinforcing agents in adhesives or sealants is known. These particles must have a particle size which is compatible with the intended use of the adhesive or sealant. The lower limit of the size of the inorganic particles is given on the one hand by their manufacturability and on the other hand by their influence on the viscosity of the adhesive or sealant. The smaller the particle size of the inorganic particles, the higher the viscosity of the adhesive or sealant at the same weight fraction of the inorganic particles. A technically useful lower limit of the average particle size is 10 nm, preferably 50 nm and in particular 100 nm. The upper limit of the particle size is given by the intended thickness of the adhesive joint. Usually, however, one chooses the upper limit much smaller than the thickness of the adhesive joint. Upper limits of 20 microns, in particular of 10 microns are common and suitable for the present invention.

The average particle size of the particles can be determined by conventional methods, for example by light scattering or electron microscopy. "Particles" are understood as meaning those particles which are dispersed in the organic matrix and which may represent agglomerates of smaller units.

For the purposes of the present invention, functional groups are considered to be "terminal" when these groups are at the ends of a pure or heteroatom-interrupted hydrocarbon chain having at least 5 atoms in the chain These functional groups may themselves be further organic radicals such as alkyl groups or alkanol groups, which may be the case for example with amino groups as "terminal groups".

As is customary, a pair of electrons in the valence shell which does not form a bond to another atom is referred to as a "free electron pair." In the context of the present invention, such heteroatoms are in particular nitrogen, oxygen or sulfur atoms.

The functional groups are preferably selected from -OH groups (which may be part of an alcohol or a carboxylic acid), -SH groups, epoxy groups and -NHR groups, where R is hydrogen or an organic radical having 1 to 12 C- Atoms means.

It is preferred that the organic molecules contain ether groups in addition to the mentioned terminal functional groups. For example, you can the organic molecules are selected from those which contain one or more ethylene oxide or propylene oxide group (s) incorporated with the opening of the epoxide ring as an ether, and terminal -OH groups, -SH groups, or -NHR groups where R is hydrogen or an organic radical having 1 to 12 carbon atoms. Specific examples are:

a) compounds of the formula HX-CHR ¹ -CHR ² - [O-CHR ¹ -CHR ² ] _n -O-CHR ² -CHR ¹ -XH where X = O or S and R ¹ and R ² either Atoms or R ^{1 is} an H atom and R ^{2 is} a methyl group, or R ^{1 is} a methyl group and R ^{2 is} a hydrogen atom and n is a number in the range of 0 to 10. A concrete example is 3,6-dioxaoctane-1, 8-dithiol of the formula HS-C ₂ H ₄ -OC ₂ H ₄ -OC ₂ H ₄ -SH. b) compounds of the formula

HRN-CHR ¹ -CHR ² - [O-CHR ¹ -CHR ² ] _n -O-CHR ² - CHR ¹ -NRH, where R is hydrogen or an organic radical having 1 to 12 C atoms and R ¹ and R ² either both H atoms or R ^{1 is} an H atom and R ^{2 is} a methyl group, or R ^{1 is} a methyl group and R ^{2 is} a hydrogen atom and n is a number in the range of 0 to 10. c) compounds of the formula

Y [-O-CHR ¹ -CHR ² - [O-CHR ¹ -CHR ² ] _n -O-CHR ² - CHR ¹ -XH] _Z , where Y represents an organic moiety which is used to form z ether and / or or R ¹ and R ^{2 are} either H atoms or R ^{1 is} an H atom and R ^{2 is} a methyl group, or R ^{1 is} a methyl group and R ^{2 is} a hydrogen atom and n is a number in the range of 0 to 10 and z is an integer in the range of 2 to 6, especially 3 to 4. The number n may be the same or different in each of the z groups. d) compounds of the formula

Y [-O-CHR ¹ -CHR ² - [O-CHR ¹ -CHR ² ] _n -O-CHR ² - CHR ¹ - NRH] ₂ , wherein Y represents an organic moiety which is used to form e.g.

Ether and / or ester groups, R is hydrogen or an organic n is 1 to 12 carbon atoms and R ¹ and R ^{2 are} either both H atoms or R ^{1 is} an H atom and R ^{2 is} a methyl group, or R ^{1 is} a methyl group and R ^{2 is} a hydrogen atom and n is a number in Range of 0 to 10 and z is an integer in the range of 2 to 6, especially 3 to 4. The number n may be the same or different in each of the z groups.

Examples of Organic Molecule Parts Y in the formulas c) and d) are the molecular radicals of ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol which are reduced by the H atoms of the OH groups and the position isomers of butyric glycol, glycerol, the positional isomers of tris-methylolethane and tris-methylolipropane, in particular 1,1,1-trismethylolpropane, erythritol, pentaerythritol, pentites and hexites, as well as sugars of the pentoses and hexoses type and the corresponding carboxylic acids which can be obtained from the abovementioned or polyhydric alcohols derived in that one or more -CH 2 -OH - groups is replaced by one carboxylate each.

In the case of the general formulas mentioned under a) to d), it is customary for the degree of ethoxylation or propoxylation to fluctuate around an average value and for this mean value to be indicated as number n. Because in the ethoxylation or propoxylation no uniform compounds, but mixtures of molecules that have a different number of ethylene oxide or propylene oxide groups. By choosing the reaction conditions and the use of special catalysts, the variation in the degree of alkoxylation can be varied. In the abovementioned formulas, n therefore indicates the average number of ethylene oxide or propylene oxide groups ring-opened under ether formation in the abovementioned molecules. Therefore, n can also represent a fractional number.

For example, organic molecules having epoxide groups may be selected those bearing glycidyl ether groups. In particular, the glycidyl ether groups may be linked directly or indirectly to the phenyl rings of bisphenols. Specific examples are bisphenol A glycidyl ethers in which the glycidyl lether groups in the 2- or 4-position on the phenyl rings, and the corresponding bisphenol-F-glycidyl ether.

It is particularly preferred if the surface of the inorganic particles has been coated to such an extent with the inorganic molecules that at least 4 carbon atoms of the organic molecules are present per nm ² surface. Preferably, at least 6 and in particular at least 8 carbon atoms of the organic molecules are present per nm ² surface area. How the coverage density can be measured will be described below.

The inorganic particles are preferably selected from oxides, hydroxides, carbonates and silicas or silicates. Oxides of titanium in particular such as rutile or anatase are suitable as oxides. Aluminum oxides or hydroxides can also be used. Zinc oxides are also suitable. The carbonates used are preferably carbonates of calcium and / or magnesium. Examples are chalk and dolomite. The inorganic particles may also be mixed oxides / hydroxides such as basic aluminas or basic zinc oxides. Mixed carbonates / hydroxides such as basic zinc carbonate may also be used.

Further preferred inorganic particles are silicas or silicates. The term "silicas" refers to (hydroxide-containing) silicon oxides which can be obtained, for example, from silicon-halogen compounds by pyrolysis or by hydrolysis Silicates can be salts of silicic acids with, in particular, alkaline-earth metals. Examples of these are bentonites, calcium silicates such as wollastonite are also suitable, as well as chlorites Other examples are mentioned below in connection with a specific method of preparation of organic particles coated with organic molecules. In a preferred embodiment, the organic molecules are connected via silicon atoms to the surface of the inorganic particles. This can be done by a reaction sequence described in WO2005 / 061631 and EP 1526115 cited herein.

These documents describe processes for the surface modification of particles of oxidic compounds of metals and / or semimetals M, on whose surface MOH groups are present, wherein in a reaction step b) the particles are brought into contact with silicon-halogen compounds under conditions such that the MOH groups react with the silicon-halogen compounds to form MO-Si-X moieties (X = halogen). Silica, silicates and aluminosilicates are also included as "oxidic compounds." On carbonates, the reaction described here is analogously transferable as long as conditions are maintained which do not lead to complete decomposition of the carbonates.

For the present invention, the particles may contain exclusively silicon as the semi-metal M, that is to say consist of silicon dioxide or "silicic acids." Furthermore, the metallic or semimetallic component M may consist only proportionally of silicon, as is the case, for example, with aluminosilicate minerals Compounds such as layered silicates such as mica, bentonites, etc. are included in the present invention as "inorganic particles". Further non-exhaustive examples of the "inorganic particles" encompassed by the invention are oxidic compounds such as, for example, titanium dioxide, zirconium oxides, zinc oxide, iron oxides, nickel oxides, manganese oxides, cerium oxides, aluminum oxides or else mixed oxides which contain the metals titanium, zinc, Zirconium, iron, cobalt, nickel, cerium and / or aluminum.

Although no MOH groups are given in the chemical formula of the oxide compounds or the carbonates, such groups are often present on the particle surface for valence saturation. The fact that this is the case can be seen from the fact that the implementation with silicon-halogen compound fertilizer is detectable takes place. Should a higher density of MOH groups on the particle surface be desired for the reaction with silicon-halogen compounds, as is usually the case with the oxidic or carbonic particles, this may increase the number of MOH groups on the particle surface in that, in a reaction step a) upstream of the reaction step b), the particle surface is brought into contact with a strong acid. This is preferably done in the aqueous phase and under conditions in which the oxidic particles or the carbonates are superficially attacked, but not dissolved. Variable parameters for this are in particular the strength of the acid, the reaction temperature and the reaction time. As strong acids here are acids of the strength of phosphoric acid and stronger acids such as sulfuric acid in particular suitable. After the superficial reaction with the acid, the particles are preferably washed before the reaction step b) and then dried.

The silicon-halogen compounds which are brought into contact with the inorganic particles in reaction step b) are preferably selected from silicon chlorides and silicon bromides, for example from silicon tetrachloride and silicon tetrabromide. The reaction is possible from the gas phase, but is preferably carried out in the liquid phase in an anhydrous medium as possible. The liquid phase should therefore contain as little water as technically possible. For example, the water content should be below 1 ppm. This ensures that the Si-halogen bonds are not hydrolyzed by water or at least only to a minor extent, while the majority of the silicon-halogen molecules are bound to the particle surface by reaction with the surface MOH groups. In this case, the reaction is preferably controlled such that 1 to 3 MO-Si bonds are formed per silicon atom, while 3 to 1, preferably 1 to 2 Si-halogen bonds are retained. These are then available for further functionalization reactions. As a liquid phase, for example, the silicon-halogen compounds to be reacted with the oxidic particles, even considered. These serve not only as a reagent, but at the same time as a reaction medium. The silicon However, halogen-containing compounds can also be brought into contact with the particles of the oxidic compounds in dry non-protic solvents. Examples of suitable non-protic solvents are cyclohexane and diethyl ether. As other non-protic solvents are liquid aromatic or aliphatic hydrocarbons such as benzene, toluene or petroleum ether into consideration.

The next process step consists in carrying out, after reaction step b), in a further reaction step c), the particles having at least one organic compound whose molecules carry at least two terminal functional groups, each functional group containing at least one heteroatom having at least one lone pair of electrons, under such conditions that Si-X bonds are cleaved and instead bonds of Si to the organic compound or to a residue thereof are formed. Examples of such organic molecules which are suitable in the context of the present invention have been mentioned above. Particularly suitable for this reaction step are those organic molecules which carry terminal -OH groups, -SH groups or -NHR groups. This reaction leads to -Si-O-, -Si-S-, or -Si-N - bonds with elimination of H-X, whereby the organic molecules with the one functional end are bound to the surface of the inorganic particles. The other end, which still has a free -OH group, -SH group or -NHR group, can react in a conventional manner with the epoxy resin to open the oxirane ring and attachment of the organic molecules to the epoxy resin. As a result, the occupied inorganic particles are covalently incorporated into the organic matrix of the adhesive or sealant.

If it is desired to prove the inorganic particles by reaction with organic molecules which carry terminal epoxide groups, it is advisable first to convert the Si-X bonds into Si-OH groups by hydrolysis (a reaction step, which is also described in WO2005 / 061631) is) and then carry out the reaction with the organic molecules, the epoxide groups wear. By reaction with the Si-OH group, an oxirane ring of the organic molecules is opened and the molecule is bonded to the inorganic particles to form a -SiO-C bond. The other end of the organic molecule still has an epoxy group, which react with the hardener components during curing of the adhesive or sealant and so can be covalently incorporated into the organic matrix of the adhesive or sealant.

In order to prevent that in this reaction step c) the Si-X bonds are hydrolyzed to Si-OH bonds, one must work according to the reaction step b) under conditions as low as possible in water. The reaction conditions indicated above in reaction step b) apply correspondingly to this reaction step c). European Patent Application EP 1526115 cites examples of corresponding reactions which have been carried out on silica particles which have surface Si-Cl groups. The details given there can be transferred to the present invention in an analogous manner. The EP document also contains further details on how the particles obtained after reaction step c) can be characterized in more detail analytically.

Of course, not only a single corresponding organic compound, but a mixture of different compounds can be used in reaction step c). This then leads to inorganic particles that carry different organic radicals on their surface.

In order to determine the occupation density per nm ² , the particle surface and, if necessary, the porosity are first measured by the BET method (for example using nitrogen). The total content of organic radicals or of the carbon atoms herein and / or of silicon on the particles can be determined by elemental analysis. For the latter, a thermogravimetric analysis and / or DSC measurement can also be used. In a thermogravimetric analysis with access of air, the organic radicals burn at elevated temperature, which leads to a loss of mass. This combustion reaction shows in an exothermic effect in a DSC measurement. For safety, the comparison can be made with a thermogravimetric analysis and / or DSC measurement of the non-occupied with the silicon-containing groups starting material. If the chemical nature of the organic radicals and their number per Si atom is known, the total number of organic radicals in moles and hence the occupation density can be determined from the weight loss. This analysis can be supported or supplemented by catching up the carbon dioxide and water produced during the combustion of the organic residues in the course of a combustion analysis and deducing the amount of collected carbon back to the number of organic residues. If the chemical nature of the organic radicals and / or their number per Si atom is unknown in the case of an unknown sample, then at least the number of carbon atoms per nm ² surface can be deduced from such analyzes. In addition, mass spectroscopic techniques can be used to elucidate the chemical nature of the organic radicals. If the total amount of coating groups or of C atoms thus obtained is based on the measured particle surface, the coverage density in groups per nm ² can be calculated. Further details can be found in the cited EP patent application EP 1526115. Instead of the number of C atoms per nm ² surface, the coverage density can also be characterized, as described in EP 1526115 and in WO2005 / 061631, by the number of bound organic molecules per nm ² surface. In the context of the present invention, this is preferably at least 2, in particular at least 3 and particularly preferably at least 4, in accordance with the two aforementioned documents EP 1526115 and WO2005 / 061631.

As is often the case with epoxy-based adhesives or sealants, it is also preferred within the scope of the present invention that it be present in two components, one component A consisting of or containing one or more epoxides and a second Component B consists of one or more curing agents for epoxides or contains. Immediately before application, these two components are mixed together. Here are in the context of present invention, epoxies and curing systems suitable, which are commonly used in the art as adhesives or sealants. Preferably, the components A and B are composed so that the same volume can be mixed for application.

In 2-component systems, a preferred embodiment is that component B contains said inorganic particles in an amount such that the proportion of inorganic particles in the total adhesive or sealant after mixing components A and B is in the range of 5 to 30 wt .-%, preferably from 5 to 20 wt .-%, wherein the surface of the inorganic particles has been occupied by reaction with organic molecules which carry at least two terminal functional groups selected from -OH groups, -SH groups and -NHR groups, where R is hydrogen or an organic radical having 1 to 12 C atoms. These functional groups correspond to typical functional groups in hardener systems and can react with the epoxide component A to open the oxirane ring and add the organic molecule.

An alternative embodiment is that the component A contains the said inorganic particles in such an amount that the proportion of the inorganic particles in the entire adhesive or sealant after mixing the components A and B in the range of 5 to 30 wt. %, preferably in the range of 5 to 20% by weight, wherein the surface of the inorganic particles has been coated by reaction with organic molecules carrying at least two terminal functional groups selected from epoxide groups. As a result, the occupied inorganic particles "epoxy resin-like" and can react with the hardener molecules of the component B opening the oxirane ring and addition of the organic molecule.

However, the adhesives or sealants according to the invention can also be present as one-component systems, the epoxy resins and activatable or latent hardeners contain. In addition, the stated inorganic particles are contained in proportions ranging from 5 to 30 wt .-%, preferably from 5 to 20 wt .-%.

As epoxy resins are a variety of polyepoxides having at least 2 1, 2-epoxy groups per molecule. The epoxide equivalent of these polyepoxides can vary between 150 and 4000. The polyepoxides may in principle be saturated, unsaturated, cyclic or acyclic, aliphatic, alicyclic, aromatic or heterocyclic polyepoxide compounds. Examples of suitable polyepoxides include the polyglycidyl ethers prepared by reaction of epichlorohydrin or epibromohydrin with a polyphenol in the presence of alkali. Examples of suitable polyphenols are resorcinol, pyrocatechol, hydroquinone, bisphenol A (bis (4-hydroxyphenyl) -2,2-propane), bisphenol F (bis (4-hydroxyphenyl) methane), bis (4-hydroxyphenyl) 1,1-isobutane, 4,4'-dihydroxybenzophenone, bis (4-hydroxyphenyl) -1,1-ethane, 1,5-hydroxynaphthalene.

Further suitable polyepoxides are the polyglycidyl ethers of polyalcohols or diamines. These polyglycidyl ethers are derived from polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol or trimethylolpropane.

Further polyepoxides are polyglycidyl esters of polycarboxylic acids, for example reactions of glycidol or epichlorohydrin with aliphatic or aromatic polycarboxylic acids such as oxalic acid, succinic acid, glutaric acid, terephthalic acid or dimer fatty acid.

Other epoxides are derived from the epoxidation products of olefinically unsaturated cycloaliphatic compounds or of native oils and fats.

Very particular preference is given to the epoxy resins which are derived by reaction of bisphenol A or bisphenol F and epichlorohydrin. It will be in the Usually mixtures of liquid and solid epoxy resins used, wherein the liquid epoxy resins are preferably based on bisphenol A and have a sufficiently low molecular weight. In particular, liquid epoxy resins are used at room temperature, which generally have an epoxide equivalent weight of 150 to about 220, more preferably an epoxide equivalent weight range of 182 to 192.

Guanidines, substituted guanidines, substituted ureas, melamine resins, guanamine derivatives, cyclic tertiary amines, aromatic amines and / or mixtures thereof can be used as thermally activatable or latent hardeners for the epoxy resin in the case of the one-component systems. The hardeners may be involved stoichiometrically in the curing reaction, but they may also be catalytically active. Examples of substituted guanidines are methylguanidine, dimethylguanidine, trimethylguanidine, tetramethylguanidine, methylisobiguanidine, dimethylisobiguanidine, tetramethylisobiguanidine, hexamethylisobiguanidine, hepamethylisobiguanidine, and especially cyanguanidine (dicyandiamide). As representatives of suitable guanamine derivatives its alkylated benzoguanamine resins, benzoguanamine resins or methoxymethyl-ethoxymethyl-benzoguanamine called. For the one-component, thermosetting hotmelt adhesives, the criterion of choice is of course the low solubility of these substances at room temperature in the resin system, so that solid, finely ground hardening agents are preferred, in particular dicyandiamide is suitable. This ensures good storage stability of the composition.

In addition to or instead of the aforementioned hardeners, catalytically active substituted ureas can be used. These are in particular the p-chlorophenyl-N, N-dimethylurea (monuron), 3-phenyl-1, 1-dimethylurea (fenuron) or 3,4-dichlorophenyl-N, N-dimethylurea (diuron). In principle, it is also possible to use catalytically active tertiary aryl or alkyl amines, such as, for example, the benzyldimethylamine, tris (dimethylamino) phenol, piperidine or piperidine derivatives, but these often have too high a solubility in the adhesive system, so that no usable one here Storage stability of the incom- ponentigen system is achieved. Furthermore, various, preferably solid, imidazole derivatives can be used as catalytically active accelerators. Representative examples include 2-ethyl-2-methylimidazole, N-butylimidazole, benzimidazole and NC ₁ to C ₁₂ -Alkyiimidazole or N-arylimidazoles.

The adhesives according to the invention can be formulated, on the one hand, as one-component adhesives, it being possible for these to be formulated both as highly viscous, warm adhesives and as thermally curable hot melt adhesives. Furthermore, these adhesives can be formulated as one-component, pre-gelling adhesives, in the latter case, the compositions contain either finely divided thermoplastic powders, such. As polymethacrylates, polyvinyl butyral or other thermoplastic (co) polymers or the curing system is tuned so that a two-stage curing process takes place, the gelling step causes only a partial curing of the adhesive and the final curing in vehicle z. B. in one of the paint ovens, preferably in the KTL furnace takes place.

The adhesive compositions according to the invention can also be formulated as two-component epoxy adhesives in which the two reaction components are mixed together shortly before application, the curing then taking place at room temperature or moderately elevated temperature. In this case, the reaction components known per se for two-component epoxy adhesives, for example di- or polyamines, amino-terminated polyalkylene glycols (for example Jeffamine, amino-poly-THF) or polyaminoamides, may be used as the second reaction component. Other reactive partners may be mercapto-functional prepolymers such. As the liquid thiokol polymers. In principle, the epoxy compositions can also be cured with carboxylic acid anhydrides as the second reaction component in two-component adhesive formulations.

Furthermore, the adhesive compositions according to the invention can be customary other auxiliaries and additives such. As plasticizers, reactive diluents, Rheolo- pouring aids, wetting agents, anti-aging agents, stabilizers and / or color pigments.

As adhesive or sealant matrix which according to the invention contains the inorganic solids coated with said organic molecules, in particular:

According to WO00 / 37554 compositions, the

A) a copolymer having at least a glass transition temperature of -3O ⁰ C or lower and epoxy reactive groups or a reaction product of this copolymer with a polyepoxide and

B) a reaction product of a polyurethane prepolymer and a polyphenol or aminophenol and

C) contain at least one epoxy resin

More detailed information can be found in said WO00 / 37554.

According to WO01 / 94492 compositions containing

B) a copolymer having a glass transition temperature of -30 ° C or lower and epoxide-reactive groups or a reaction product of this copolymer with a stoichiometric excess of an epoxy resin according to A)

C) a latent, high temperature activatable hardener for component A), and either

E) a reaction product prepared from a tri- or polyfunctional polyol or a tri- or polyfunctional amino-terminated polymer and a cyclic carboxylic anhydride, wherein the reaction product contains on average more than one carboxyl group per molecule, or F) a mixture of the reaction products according to D) and E). More detailed information can be found in said WO 01/94492.

According to WO00 / 20483 compositions containing

A) a copolymer having at least a glass transition temperature of - 3O ⁰ C or lower and epoxide-reactive groups

B) a reaction product preparable by reacting a carboxylic anhydride or dianhydride with a di- or polyamine and a polyphenol or aminophenol

C) at least one epoxy resin.

More detailed information can be found in said WO00 / 20483.

According to WO03 / 055957 a thermosetting structural adhesive with multiphase polymer morphology, wherein the binder matrix of the cured reaction adhesive a) a continuous phase consisting of an optionally crosslinked polymer P1 having a glass transition temperature above 100 ⁰ C, preferably above 120 ⁰ C, b) a Heterodisperse phase consisting of individual continuous regions of a thermoplastic or elastomeric polymer P2 having a glass transition temperature of less than -30 ⁰ C and an average particle size between 0.5 and 50 microns, which in turn separated phases of another thermoplastic or elastomeric polymer P3 having a glass transition temperature of less than -30 ⁰ C and a size between 1 nm and 100nm, which may be partially aggregated to larger agglomerates, and c) embedded in the continuous phase further heterodisperse phase consisting of areas of a ther moplastic or elastomeric polymers P3 with a glass transition temperature of less than -30 ⁰ C, which are at least partially have an average particle size between 1 nm and 50 nm, where P3 is not identical to P2, having.

Details of this can be found in WO03 / 055957.

According to DE 10351687 a two-component epoxy resin composition containing

A) an epoxy component comprising a) at least one epoxy resin having an epoxy functionality greater than 1, b) at least one heat-activatable hardener for the epoxy resin,

B) a liquid or pasty hardener component containing amines, polyaminoamides, Mannich bases or mercapto group-containing compounds. Details can be found in the aforementioned DE 10351687.

In addition to the applications mentioned above, the adhesive compositions according to the invention can also be used as potting compounds in the electrical or electronics industry, as a die-attach adhesive in electronics for bonding components to printed circuit boards. Further possible uses of the compositions of the invention are matrix materials for composites such. B. fiber reinforced composites.

Further preferred fields of application for the adhesive compositions according to the invention both in one-component thermosetting form and in two-component form are their use as structural foam, for example for forming internal reinforcements of cavities in vehicle construction, wherein the expanding structural foams stiffen the cavity structure of the vehicle or increase its degree of energy absorption. Furthermore, the compositions can be used for the production of so-called "stiffening pads" or for stiffening coatings of thin-walled metal sheets or plastic components, preferably in vehicle construction. However, a very particularly preferred field of application of the adhesives according to the invention are structural bonds in vehicle construction.

When used according to the invention as a structural adhesive, the adhesive is thermally cured after the connection of the metal parts at a temperature in the range of 100 to 150 ⁰ C for a period in the range of 30 to 120 minutes. In particular, the curing may be carried out for a period in the range of 50 to 70 minutes at a temperature in the range of 110 to 130 ⁰ C. In the following examples, curing was carried out at 120 ^° C. for one hour. The optimum curing time and curing temperature depend on the particular epoxy-hardener system used and can be optimized by routine experiments.

The metal parts to be bonded may consist of those metals that are currently customary in automotive engineering. Examples include steel, galvanized or alloy-galvanized steel and aluminum. Also a bonding of magnesium parts is possible. The metal parts to be bonded may be subjected to anticorrosive treatment prior to bonding or may have been coated with an organic primer, as is currently the practice in the art. Non-pretreated, possibly even oiled parts can also be bonded.

embodiments

The different fillers mentioned below were coated with the following functional groups ("nucleophiles") according to the method described in WO2005 / 061631. The filled fillers (and blank fillers for comparison) were mixed in different amounts (expressed in wt .-% based on the filler-containing end product) incorporated into a 2-component epoxy adhesive:

Formulation: 2-K-EPO Equiv ^■

Component A Mass [%] Equivalent Components [%] Wt

Epon 828 182 100 0.549 50

Equiv ■

Component B Mass [%] Equivalent Components [%] Wt

Polypox P 502 92 66.67 0.725 33.33

Hycar ATBN 1300X16 900 33.33 0.037 16.67

The individual components are

Epon 828 epoxy resin based on bisphenol-A and epichlorohydrin

Polypox P 502 modified polyammoamide oxide resin

Hycar ATBN 1300X16 amine-terminated butadiene-acrylonitrile copolymer

Curing for ¹ h at 120 ^° C. Measurement parameters:

Tensile shear strength Material of the test piece sheet metal

Length of bonding 10 mm

Width of the test piece 25 mm

Test speed 15 mm / min

Angle scarf resistance Material of the test specimen sheet metal

Width of the test piece 25 mm

Measuring path 200 mm

Test speed 100 mm / min

Abbreviations surface near the surface

Cf cohesive failure slanted uneven bending of the joint

Testing the angle scarf resistance

Rutile (Kronos 3025)

Nucleophile: 3,6-dioxa-1,8-dithiol Tab. 1: Tensile shear strength

Tab. 2: Angle peel strength Rutile (Kronos 3025)

Nucleophile: Jeff at ine T -403

Tab. 3: Tensile shear strength

Tab. 4: Angle peel strength

Rutile (Kronos 3025)

Nucleophile: thiol / DER 331

Tab. 5: Tensile shear strength

Tab. 6: Angle peel strength

Chalk (Socal U1)

Nucleophile: 3,6-dioxa-1,8-dithiol

Tab. 11: Tensile shear strength

Tab. 12: Angle peel strength

Chalk (Socal U1)

Nucleophile: Jeffamine T -403 Tab. 11: Tensile shear strength

Tab. 12: Angle peel strength

impact peel measurements:

Impact Peel Impact Peel

Sample no. Filler Nucleophile content 22 ⁰ C. -20 ⁰ C

% J J

1 without - 7,2

2 rutile (Kronos 3025) without 5 8.8 / 4.7 3 10 5.0 4 20 0.7 0.1 O.

5 rutile (Kronos 3025) 3,6-dioxa-1,8-dithiol 5 7.8 6 10 7.1

7 20 5,6

8 rutile (Kronos 3025) Jeffamine T-403 5 9.5 3.4 9 10 7.3 10 20 7.7 2.1

11 Rutile (Kronos 3025) DER 331 5 8.9 3.7 12 10 7.2 13 20 5.8

Claims

claims

An epoxy-based adhesive or sealant containing, based on the total adhesive, 5 to 30% by weight of inorganic particles whose surface has been coated by reaction with organic molecules bearing at least two terminal functional groups, each functional group contains at least one heteroatom with at least one lone pair of electrons.

2. Adhesive or sealant according to claim 1, characterized in that the functional groups are selected from -OH groups, -SH groups, epoxy groups and -NHR groups, wherein R is hydrogen or an organic radical having 1 to 12 C Atoms means

3. adhesive or sealant according to one or both of claims 1 and 2, characterized in that the organic molecules contain ether groups in addition to said terminal functional groups.

4. adhesive or sealant according to one or more of claims 1 to 3, characterized in that the surface of the inorganic particles was coated to such an extent with the organic molecules that per nm ² surface at least 4 carbon atoms of the organic molecules are present.

5. adhesive or sealant according to one or more of claims 1 to 4, characterized in that the inorganic particles are selected from oxides, hydroxides, carbonates and silicas or silicates.

6. adhesive or sealant according to one or more of claims 1 to 5, characterized in that the organic molecules are connected via silicon atoms with the surface of the inorganic particles.

7. adhesive or sealant according to one or more of claims 1 to 6, characterized in that it is present in two components, wherein a component A consists of one or more epoxide (s) or contains these and a second component B from one or consists of or contains several hardeners for epoxides.

8. adhesive or sealant according to claim 7, characterized in that the component B contains said inorganic particles in an amount such that the proportion of inorganic particles in the entire adhesive or sealant after mixing the components A and B in the range from 5 to 30% by weight, preferably in the range of 5 to 20% by weight, the surface of the inorganic particles being coated by reaction with organic molecules bearing at least two terminal functional groups selected from -OH groups -SH groups and -NHR groups, wherein R is hydrogen or an organic radical having 1 to 12 carbon atoms.

9. adhesive or sealant according to claim 7, characterized in that the component A contains said inorganic particles in an amount such that the proportion of inorganic particles in the entire adhesive or sealant after mixing the components A and B in the range from 5 to 30% by weight, preferably in the range of 5 to 20% by weight, the surface of the inorganic particles being coated by reaction with organic molecules bearing at least two terminal functional groups selected from epoxide groups.

10. Use of an adhesive according to one or more of claims 1 to 9 as a structural adhesive for the connection of metal parts in the automotive industry.

11.Use according to claim 10, characterized in that the adhesive after the connection of the metal parts at a temperature in the range of 100 to 150 ⁰ C for a period of time in the range of 30 to 120 minutes is thermally cured.