One-component thermosetting epoxy composition with improved adhesion

Abstract

The present invention relates to a one-component, thermosetting epoxy resin composition comprising at least one epoxy resin A having an average of more than one epoxy group per molecule, at least one latent hardener B for the epoxy resin, at least one impact modifier D, at least one physical or chemical blowing agent E, and fibrous anhydrous basic magnesium sulfate (MOS). The present invention provides a thermally expandable epoxy resin composition having improved adhesion, particularly on metal substrates.

Description

Technical Field

[0001] The present invention belongs to the field of heat-expandable one-component thermosetting epoxy resin compositions, in particular to compositions for producing structural foams and reinforcement of hollow structures, products for reinforcing hollow structures, their use in reinforcing hollow structures and methods for reinforcing hollow structures. Existing technology

[0002] An important area of application for thermally expandable thermosetting epoxy resin additives is found in vehicle construction, in particular when foaming cavities in body-in-white.

[0003] Manufactured products often contain hollow parts that result from the manufacturing process and / or are designed into the product for various purposes, such as weight reduction. For example, an automotive vehicle includes several such hollow parts throughout the vehicle, including in the roof, hood, trunk lid, and doors.

[0004] It is often desirable to connect / join parts / substrates so as to additionally form hollow parts at least in certain locations in order to reinforce such openings and cavities, so that the structure becomes more resistant to mechanical stresses, but with the advantage of maintaining a low weight of the hollow structure.

[0005] For example, during the manufacturing process of an automobile, a hollow part of a roof may contain a layer or strip of uncured thermosetting epoxy resin composition applied between a roof beam and a top layer and may still be mostly covered with an electrophoretic coating liquid while an applied thermosetting epoxy resin composition has been inserted between an upper top layer and a lower top layer, and thereafter during a heat treatment step, the expandable thermosetting epoxy resin composition expands and firmly connects the two layers to strengthen the structure of the vehicle.

[0006] It is therefore desirable to obtain thermally expandable thermosetting epoxy resin compositions which exhibit good material properties after curing, in particular good adhesion to substrates, in particular metal substrates. SUMMARY OF THE INVENTION

[0008] It was therefore an object of the present invention to provide heat-expandable epoxy resin compositions having improved adhesion, in particular on metal substrates.

[0009] It has surprisingly been found that this object can be achieved by a one-component thermosetting epoxy resin composition as described herein.

[0010] Further aspects of the invention are the subject matter of further independent claims. Particularly preferred embodiments of the invention are the subject matter of the dependent claims.

[0011] Certain embodiments of the present invention

[0012] Therefore, the present invention relates to a one-component thermosetting epoxy resin composition comprising:

[0013] 20-55% by weight, more particularly 25-50% by weight, preferably 25-45% by weight, 25-40% by weight, most preferably 25-35% by weight of at least one epoxy resin A having on average more than one epoxy group per molecule;

[0014] 1 to 6% by weight, more particularly 2 to 5% by weight, preferably 2 to 4% by weight, of at least one latent hardener B for an epoxy resin;

[0015] - 0-3% by weight, more particularly 0.1-2.5% by weight, 0.1-2.0% by weight, 0.1-1.5% by weight, preferably 0.1-1.0% by weight, of at least one accelerator C;

[0016] 10-50% by weight, more particularly 15-45% by weight, 20-45% by weight, 30-45% by weight, preferably 30-40% by weight, of at least one impact modifier D, based on the total weight of the epoxy resin composition;

[0017] - 0.01-5% by weight, more particularly 0.1-4% by weight, 0.25-4% by weight, preferably 0.5-3.5% by weight, of at least one physical or chemical blowing agent E; and

[0018] 2-35% by weight, more particularly 5-30% by weight, 7.5-25% by weight, preferably 7.5-20% by weight, most preferably 10-15% by weight of fibrous anhydrous magnesium oxysulfate (MOS).

[0019] Epoxy resin compositions are one-component, meaning that the components of the epoxy resin composition, more particularly the epoxy resin and the hardener, are present as a single component and do not cure at normal ambient or room temperature. They can therefore be handled in this form, whereas in the case of two-component systems, the components cannot be mixed until immediately prior to use.

[0020] Curing of the one-component epoxy resin composition is achieved by heating, typically at temperatures above 70°C, for example in the range of 100-220°C.

[0021] The prefix "poly" in expressions such as polyol or polyisocyanate indicates that the compound has two or more of the groups in question. For example, a polyisocyanate is a compound having two or more isocyanate groups.

[0022] The expression "independently of one another" as used hereinafter means that in the same molecule, two or more identically represented substituents may, as defined, have the same or different meanings.

[0023] The dashed lines in the formulae in this document represent in each case the bond between the substituent in question and the remainder of the molecule to which it is attached.

[0024] Unless otherwise indicated, room temperature here refers to a temperature of 23°C.

[0025] The one-component thermosetting epoxy resin composition preferably has a needle penetration value (at 0.1 mm) of 20-80, more preferably 30-75, 40-70, most preferably 50-70, measured at 23° C. with a needle thickness of 1 mm and a total load of 100 g (the weight of the needle and the relevant parts) for 5 seconds. Preferably, the needle penetration value is measured as described in the experimental part.

[0026] A disadvantage of values above 80 is that the composition becomes very soft and therefore difficult to handle and apply. The composition also has reduced dimensional stability during handling / application.

[0027] A disadvantage of values below 20 is that the composition becomes very hard and therefore difficult to apply due to its low viscosity and plasticity. Low plasticity also causes difficulties when the composition on the substrate is bent or comes into contact with additional substrates after application.

[0028] The thermosetting one-component epoxy resin composition comprises 20-55 wt. % of at least one epoxy resin A having an average of more than one epoxy group per molecule, based on the total weight of the one-component thermosetting epoxy resin composition. The epoxy groups are preferably in the form of glycidyl ether groups.

[0029] The fraction of epoxy resin A having an average of more than one epoxy group per molecule is preferably 25-50 wt. %, more preferably 25-45 wt. %, 25-40 wt. %, most preferably 25-35 wt. %, based on the total weight of the one-component thermosetting epoxy resin composition.

[0030] The epoxy resin A having an average of more than one epoxy group per molecule is preferably a liquid epoxy resin or a solid epoxy resin. The term "solid epoxy resin" is well known to those skilled in the art of epoxides and is used in contrast to "liquid epoxy resins." The glass transition temperature of solid resins is above room temperature, meaning that they can be comminuted into pourable powders at room temperature.

[0031] Preferred epoxy resins have formula (II)

[0032]

[0033] In this formula, the substituents R' and R" are independently H or CH3.

[0034] In solid epoxy resins, the index s has a value >1.5, more particularly 2-12.

[0035] Solid epoxy resins of this type are commercially available, for example, from Dow or Huntsman or Hexion.

[0036] Compounds of formula (II) with an index s of 1 to 1.5 are referred to by those skilled in the art as semi-solid epoxy resins. For the purposes of the present invention, they are also considered to be solid resins. However, preferred solid epoxy resins are epoxy resins in the narrow sense, in other words epoxy resins with an index s of >1.5.

[0037] In the case of liquid epoxy resins, the index s has a value less than 1. Preferably, s has a value less than 0.2.

[0038] The resins in question are therefore preferably diglycidyl ether of bisphenol A (DGEBA), diglycidyl ether of bisphenol F and diglycidyl ether of bisphenol A / F. These types of liquid resins can be used, for example, as GY 250, PY 304, GY 282 (Huntsman) or DER TM 331 or DER TM 330 (Dow) or Epikote 828 (Hexion).

[0039] Further suitable epoxy resins A are so-called epoxy novolacs. These compounds have, in particular, the following formula:

[0040] in or CH2, R1=H or methyl and z=0 to 7.

[0041] More particularly these are phenol epoxy resins or cresol epoxy novolacs (R2=CH2).

[0042] These types of epoxy resins are available under the trade names EPN or ECN as well as Commercially available from Huntsman or in the product line DEN from Dow Chemical TM Inside.

[0043] Epoxy resin A is preferably a mixture of a solid epoxy resin of formula (II) and a liquid epoxy resin of formula (II). Preferably, the weight ratio of the solid / liquid epoxy resin of formula (II) is 0.2-5, preferably 1-5, more preferably 2-5.

[0044] The thermosetting one-component epoxy resin composition further comprises 1-6 wt. % of at least one epoxy resin latent hardener B, based on the total weight of the one-component thermosetting epoxy resin composition. The latent hardener is substantially inert at room temperature and is activated by elevated temperatures, typically 70° C. or higher, thereby initiating the curing reaction. Conventional epoxy resin latent hardeners can be used. Latent epoxy resin hardeners containing nitrogen are preferred.

[0045] The latent hardener B is preferably selected from the group consisting of dicyandiamide, guanamine, guanidine, aminoguanidine and derivatives thereof, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide.

[0046] The latent hardener B is preferably used in a stoichiometric amount based on the epoxy groups in the composition. The molar ratio of epoxy groups to active hydrogens of the latent hardener is preferably 0.8 to 1.2, in particular 0.9 to 1.1, preferably 0.95 to 1.05.

[0047] The fraction of latent hardener is preferably 2 to 5% by weight, preferably 2 to 4% by weight, based on the total weight of the one-component thermosetting epoxy resin composition.

[0048] The thermosetting one-component epoxy resin composition further comprises 0-3 wt %, more particularly 0.1-2.5 wt %, 0.1-2.0 wt %, 0.1-1.5 wt %, preferably 0.1-1.0 wt % of at least one accelerator C, based on the total weight of the one-component thermosetting epoxy resin composition.

[0049] Preferred accelerators C are substituted ureas, more particularly selected from the group consisting of 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea (chlorotoluron), p-chlorophenyl-N,N-dimethylurea (monuron), 3-phenyl-1,1-dimethylurea (fenuron), 3,4-dichlorophenyl-N,N-dimethylurea (diuron), N,N-dimethylurea, N-isobutyl-N',N'-dimethylurea and 1,1'-(hexane-1,6-diyl)bis(3,3'-dimethylurea). A particularly preferred accelerator C is N,N-dimethylurea.

[0050] The thermosetting one-component epoxy resin composition further comprises 10 to 50 wt % of at least one impact modifier D, based on the total weight of the one-component thermosetting epoxy resin composition.

[0051] The addition of impact modifiers is mainly used to improve the strength of thermosetting epoxy resin compositions against impact forces.

[0052] The impact modifier D can be solid or liquid.

[0053] The impact modifier D is preferably selected from the group consisting of a blocked polyurethane polymer D1, a carboxyl-terminated acrylonitrile / butadiene copolymer D2, an epoxy-terminated acrylonitrile / butadiene copolymer D3, a liquid rubber D4, and a core-shell polymer D5. More preferably, the impact modifier D is selected from the group consisting of a blocked polyurethane polymer D1, a carboxyl-terminated acrylonitrile / butadiene copolymer D2, and a liquid rubber D4, in particular a blocked polyurethane polymer D1 and a carboxyl-terminated acrylonitrile / butadiene copolymer D2.

[0054] The preferred impact modifier D1 is a terminally blocked polyurethane prepolymer of the following formula (III):

[0055]

[0056] In this formula, R 1 It is the p-valent residue of the linear or branched polyurethane prepolymer PU1 terminated by an isocyanate group after removing the terminal isocyanate group, and p is 2-8.

[0057] In addition, R 2 is independently at each occurrence selected from the following substituents

[0058]

[0059] ---OR 18 and

[0060] In these formulas, R 5 、R 6 、R 7 and R 8 Each is independently an alkyl or cycloalkyl or aralkyl or arylalkyl group, or R 5 Together with R 6 , or R 7 Together with R 8 forming part of an optionally substituted 4-7 membered ring.

[0061] In addition, R 9 、R 9’ and R 10 Each is independently an alkyl or aralkyl or arylalkyl group, or an alkoxy or aryloxy or aralkyloxy group, and R 11 is an alkyl group.

[0062] R 12 、R 13 and R 14 Each is independently of one another an alkylene group having 2 to 5 C atoms, which may have a double bond or is substituted, or a phenylene group or a hydrogenated phenylene group.

[0063] R 15 、R 16 and R 17 Each is independently H, or an alkyl group, or an aryl group or an aralkyl group, and R 18 is an aralkyl group or a monocyclic or polycyclic, substituted or unsubstituted aromatic group, which optionally has an aromatic hydroxyl group.

[0064] Finally, R 4 is the residue of an aliphatic, cycloaliphatic, aromatic or araliphatic epoxide containing a primary or secondary hydroxyl group after removal of the hydroxyl and epoxy groups, and m is 1, 2 or 3.

[0065] In one aspect, after removal of the hydroxyl group, consider as R 18 The residues of phenols or polyphenols, in particular bisphenols, are particularly preferred. Preferred examples of such phenols and bisphenols are, in particular, phenol, cresol, resorcinol, catechol, cardanol (3-pentadecenylphenol (from cashew nut shell liquid)), nonylphenol, phenols reacted with styrene or with dicyclopentadiene, bisphenol A, bisphenol F and 2,2′-diallylbisphenol A.

[0066] On the other hand, after removing the hydroxyl group, considering as R 18 The residues of are in particular hydroxybenzyl alcohol and benzyl alcohol.

[0067] If R 5 、R 6 、R 7 、R 8 、R 9 、R 9’ 、R 10 、R 11 、R 15 、R 16 or R 17 is an alkyl group, this group is more particularly a linear or branched C1-C 20 Alkyl group.

[0068] If R 5 、R 6 、R 7 、R 8 、R 9 、R 9’ 、R 10 、R 15 、R 16 、R 17 or R 18 is an aralkyl group, this moiety is more particularly an aryl group bonded via a methylene group, and more particularly a benzyl group.

[0069] If R5 、R 6 、R 7 、R 8 、R 9 、R 9’ or R 10 is an alkaryl group, this group is more particularly a C1-C2- 20 Alkyl groups, such as tolyl or xylyl.

[0070] Residue R 2 Preferred substituents are

[0071] ---OR 18 or

[0072] After removing the NH proton, the formula A preferred substituent for is ε-caprolactam.

[0073] After removing the hydrogen atom of phenol, the formula is ---OR 18 Preferred substituents of are monophenols or polyphenols, more particularly monophenols or bisphenols. 2 Particularly preferred examples are residues selected from the group consisting of

[0074]

[0075] The residue Y here is a saturated or ethylenically unsaturated hydrocarbon residue having 1 to 20 carbon atoms, more particularly having 1 to 15 carbon atoms. Preferred as Y are in particular allyl, methyl, nonyl, dodecyl or an unsaturated carbon having 1 to 3 double bonds. 15 Alkyl group.

[0076] The terminally blocked polyurethane prepolymer of formula (I) is prepared by reacting an isocyanate-terminated linear or branched polyurethane prepolymer PU1 with one or more isocyanate-reactive compounds R 2 Preparation H. If a plurality of such isocyanate-reactive compounds are used, the reaction can be carried out sequentially or with a mixture of these compounds.

[0077] The reaction is carried out in such a way that the isocyanate-reactive compound or compounds R are used stoichiometrically or in a stoichiometric excess. 2 H, in order to ensure that all NCO groups are converted.

[0078] R 1 The polyurethane prepolymer PU1 can be composed of at least one diisocyanate or triisocyanate and a polymer Q having terminal amino, thiol or hydroxyl groups. PM preparation.

[0079] Suitable diisocyanates are aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, in particular 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, 1,5-naphthalene diisocyanate (NDI), dicyclohexylmethyl diisocyanate (HDI), diisocyanate (D ... 12 MDI), paraphenylene diisocyanate (PPDI), meta-tetramethylxylene diisocyanate (TMXDI), and dimers thereof. HDI, IPDI, MDI or TDI is preferred.

[0080] Suitable triisocyanates are trimers or biurets of aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, especially the isocyanates and biurets of diisocyanates described in the preceding paragraph.

[0081] It will be appreciated that suitable mixtures of diisocyanates or triisocyanates may also be used.

[0082] Particularly suitable polymers Q have terminal amino, thiol or hydroxyl groups PM is a polymer having two or more terminal amino, thiol or hydroxyl groups Q PM .

[0083] Polymer Q PM Advantageously, the NCO-reactive groups have an equivalent weight of 300 to 6000, in particular 600 to 4000 and especially 700 to 2200 g / equivalent.

[0084] Polymer Q PM Advantageously, the polyol is a difunctional or higher functionality polyol having an OH equivalent weight of 300 to 6000 g / OH equivalent, in particular 600 to 4000 g / OH equivalent, preferably 700-2200 g / OH equivalent. Advantageously, the polyol is selected from the group consisting of polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol block copolymers, polybutylene glycol, hydroxyl-terminated polybutadiene, hydroxyl-terminated butadiene / acrylonitrile copolymers, hydroxyl-terminated synthetic rubbers, and hydrogenation products thereof and mixtures of these polyols.

[0085] In addition, the polymer Q used PM Also difunctional or higher functionality amino-terminated polyethylene ethers, polypropylene ethers, such as Polytetramethylene ethers, polybutadienes, butadiene / acrylonitrile copolymers, such as those sold under the name ATBN is sold under the name Nanoresins AG, Germany, and further amino-terminated synthetic rubbers or mixtures of the components mentioned.

[0086] Preferred polymer Q PM The polyol has an average molecular weight between 600 and 6000 g / mol and is selected from the group consisting of polyethylene glycol, polypropylene glycol, polyethylene glycol-polypropylene glycol block polymers, polybutylene glycol, hydroxyl-terminated polybutadiene, hydroxyl-terminated butadiene-acrylonitrile copolymers and mixtures thereof.

[0087] Particularly preferred polymers Q PM These are α,ω-dihydroxypolyalkylene glycols having C2-C6-alkylene groups or mixed C2-C6-alkylene groups terminated with amino groups, thiol groups, or preferably hydroxyl groups. Polypropylene glycol or polybutylene glycol are particularly preferred. Hydroxyl-terminated polyoxybutylene glycols are also particularly preferred.

[0088] Carbonyl terminated acrylonitrile / butadiene copolymer or its derivative impact modifier D2 can be traded under the name CTBN was commercially available from Nanoresins AG, Germany.

[0089] Epoxy terminated acrylonitrile / butadiene copolymer or its derivative impact modifier D3 can be traded under the name HyPox TM , such as HyPox TM RA1340 or HyPox TM RA840 is commercially available from Emerald Performance Materials LLC.

[0090] Preferred liquid rubbers D4 are NBR and SBR.

[0091] The amount of impact modifier D is preferably 15-45 wt%, 20-45 wt%, 30-45 wt%, more preferably 30-40 wt%, based on the total weight of the epoxy resin composition.

[0092] The thermosetting one-component epoxy resin composition further comprises 0.01 to 5 wt % of at least one physical or chemical blowing agent E, based on the total weight of the one-component thermosetting epoxy resin composition.

[0093] Chemical foaming agents are organic or inorganic substances that form or separate gaseous substances under the influence of temperature, humidity, electromagnetic radiation or chemicals. Such substances are particularly azodicarbonamide, sulfonylhydrazide, bicarbonate or carbonate. Compounds can be used as physical foaming agents, for example, when temperature, pressure or volume changes, particularly when temperature rises, they become gaseous substances and therefore form foam structures by volume expansion. Such physical foaming agents are particularly liquids that evaporate at elevated temperatures. In addition, gases or low-boiling liquids can be used as physical foaming agents, which are introduced into compositions in the form of microcapsules. Both chemical and physical foaming agents can produce foam structures in polymer compositions.

[0094] Preferred physical blowing agents are expandable microspheres, which consist of a thermoplastic shell filled with a heat-expandable liquid or gas. Such microspheres are available, for example, under the trade name Commercially available from Akzo Nobel, The Netherlands.

[0095] The blowing agent may preferably be foamed at a temperature of 160-160°C, particularly 80-150°C, preferably 90-140°C.

[0096] The proportion of the at least one physical or chemical blowing agent E is advantageously 0.1 to 4% by weight, 0.25 to 4% by weight, preferably 0.5 to 3.5% by weight, based on the total weight of the one-component heat-curing epoxy resin composition.

[0097] The thermosetting one-component epoxy resin composition further comprises 2-35 wt % of fibrous anhydrous basic magnesium sulfate (MOS), based on the total weight of the one-component thermosetting epoxy resin composition.

[0098] The proportion of the fibrous anhydrous basic magnesium sulfate MOS is preferably 5-30 wt %, 7.5-25 wt %, more preferably 7.5-20 wt %, most preferably 10-15 wt %, based on the total weight of the one-component thermosetting epoxy resin composition.

[0099] Surprisingly, it has been found that the aforementioned amounts of fibrous anhydrous basic magnesium sulfate (MOS) lead to improved mechanical properties of the cured epoxy resin composition, in particular improved adhesion, in particular to metal substrates, while maintaining the volume expansion properties. In particular, the lap shear values and failure modes can surprisingly be significantly improved.

[0100] This can be seen, for example, by the effect of varying the amount of MOS in E1-E3 on the lap shear strength values and on the failure mode in Table 1. Comparison of Ref.1-Ref.3 with E1 shows the differences between MOS and various similar components commonly used as fillers such as calcium carbonate, recycled carbon fiber and wollastonite.

[0101] Preferably, the fibrous anhydrous basic magnesium sulfate MOS (MgSO4.5Mg(OH)2) is selected from MgSO4.5Mg(OH)2.3H2O and MgSO4.5Mg(OH)2.8H2O, preferably MgSO4.5Mg(OH)2.3H2O.

[0102] Preferably, the length of the fibrous anhydrous basic magnesium sulfate MOS is 3 to 1000 μm, preferably 5 to 100 μm, more preferably 7.5 to 50 μm, most preferably 7.5 to 20 μm.

[0103] Preferably, the diameter of the fibrous anhydrous basic magnesium sulfate MOS is 0.1 to 5 μm, preferably 0.2 to 2 μm, more preferably 0.3 to 1 μm, and most preferably 0.4 to 0.8 μm.

[0104] Preferably, the BET specific surface area of the fibrous anhydrous basic magnesium sulfate MOS is less than 30 m 2 / g, preferably 2.5 to 20m 2 / g, more preferably 5 to 15m 2 / g.

[0105] In a preferred embodiment, the one-component thermosetting epoxy resin composition further comprises at least one filler F. Preferred fillers include mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated or ground), dolomite, quartz, silica (fumed or precipitated), cristobalite, calcium oxide, aluminum hydroxide, hollow ceramic beads, hollow glass beads, hollow organic beads, glass beads, glass fibers, and color pigments. Particularly preferred are fillers selected from the group consisting of calcium carbonate, calcium oxide, talc, glass fibers, and fumed silica, with talc, glass fibers, and fumed silica being more preferred.

[0106] The total fraction of the total fillers F is advantageously 3 to 50% by weight, preferably 5 to 40% by weight, 8 to 35% by weight, based on the total weight of the epoxy resin composition.

[0107] One-component heat-curing epoxy resin compositions may comprise further ingredients, especially catalysts, stabilizers, in particular heat and / or light stabilizers, thixotropic agents, plasticizers, solvents, dyes and pigments, corrosion inhibitors, surfactants, defoamers and adhesion promoters.

[0108] The one-component thermosetting epoxy resin composition may also contain one or more additives. Examples of additives that can be used are processing aids such as waxes, antioxidants, UV stabilizers, dyes, biocides or flame retardants.

[0109] The proportion of processing aids is advantageously 1 to 8% by weight, preferably 2 to 5% by weight, based on the total weight of the composition.

[0110] The one-component thermosetting epoxy resin composition is preferably tacky at 23°C. The term "tacky" in this document refers to surface tack in the sense of instantaneous adhesion or stickiness, which is preferably sufficient at 23°C so that when pressed with a thumb, a pressure of 5 kg is applied to the surface of the thermosetting epoxy resin composition for 1 second, and the thumb remains stuck to the surface of the thermosetting epoxy resin composition. Preferably, in this manner, after applying a pressure of 5 kg for 1 second at 23°C, the thermosetting epoxy resin composition having an inherent weight of 50 g can be lifted for at least 5 seconds.

[0111] Particularly preferred thermosetting one-component epoxy resin compositions comprise:

[0112] 20-55% by weight, more particularly 25-50% by weight, preferably 25-45% by weight, 25-40% by weight, most preferably 25-35% by weight of at least one epoxy resin A having an average of more than one epoxy group per molecule, preferably epoxy resin A is a mixture of a solid epoxy resin of formula (II) and a liquid epoxy resin of formula (II);

[0113] 1 to 6% by weight, more particularly 2 to 5% by weight, preferably 2 to 4% by weight, of at least one latent hardener B for an epoxy resin, preferably dicyandiamide;

[0114] - 0-3% by weight, more particularly 0.1-2.5% by weight, 0.1-2.0% by weight, 0.1-1.5% by weight, preferably 0.1-1.0% by weight, of at least one accelerator C, preferably a substituted urea;

[0115] 10-50% by weight, more particularly 15-45% by weight, 20-45% by weight, 30-45% by weight, preferably 30-40% by weight, of at least one impact modifier D, preferably chosen from the group consisting of blocked polyurethane polymers D1, carboxyl-terminated acrylonitrile / butadiene copolymers D2 and liquid rubbers D4, in particular blocked polyurethane polymers D1 and carboxyl-terminated acrylonitrile / butadiene copolymers D2;

[0116] - 0.01-5% by weight, more particularly 0.1-4% by weight, 0.25-4% by weight, preferably 0.5-3.5% by weight, of at least one physical or chemical blowing agent E; and

[0117] - 2-35% by weight, more particularly 5-30% by weight, 7.5-25% by weight, preferably 7.5-20% by weight, most preferably 10-15% by weight of fibrous anhydrous basic magnesium sulfate MOS;

[0118] - preferably 5 to 40% by weight, preferably 20 to 40% by weight, based on the total weight of the epoxy resin composition, of a filler F selected from calcium carbonate, calcium oxide, talc, glass fibers and fumed silica.

[0119] The thermosetting epoxy resin composition has a needle penetration value (at 0.1 mm) of 20-80, more preferably 30-75, 40-70, most preferably 50-70, measured at 23°C with a needle thickness of 1 mm using a total load of 100 g (weight of needle and related parts) for 5 seconds.

[0120] The thermosetting epoxy resin composition is preferably viscous at 23°C.

[0121] It may also be advantageous if the preferred one-component heat-curing epoxy resin composition consists to the extent that it consists of more than 80% by weight, preferably more than 90% by weight, more particularly more than 95% by weight, particularly preferably more than 98% by weight and most preferably more than 99% by weight of the aforementioned components, based on the total weight of the epoxy resin composition.

[0122] The composition according to the invention can be obtained by mixing the components in any suitable mixing apparatus, for example in a dispersing mixer, planetary mixer, twin-screw mixer, continuous mixer, extruder or twin-screw extruder.

[0123] After mixing, the resulting compositions can be formed into their desired shapes by extrusion, blow molding, pelletizing, injection molding, compression molding, blanking or stamping, or any other suitable method.

[0124] Mixing the components preferably includes an extrusion step and the mixed and extruded composition is then pelletized.The pelletized composition is then preferably brought into its desired shape by injection molding.

[0125] The foaming of the one-component thermosetting epoxy resin composition is preferably carried out independently of the curing of the epoxy resin composition, in particular in advance. As a result, the epoxy resin composition cures only when foaming of the epoxy resin composition has occurred in large quantities. Otherwise, the epoxy resin composition hardens before it reaches the desired position through foaming. Therefore, it is preferred that the curing temperature of the epoxy resin composition is higher than the foaming temperature of the epoxy resin composition.

[0126] Preferably, the one-component thermosetting epoxy resin composition exhibits the following properties after curing:

[0127] Volume expansion rate after 20 minutes at 180°C: 50-400%, preferably 80-300%, more preferably 100-200%

[0128] Lap shear strength after 10 min at 155°C: 1-20 MPa, preferably 2-15 MPa, more preferably 3-10 MPa.

[0129] Preferably, the one-component thermosetting epoxy resin composition can be foamed and thermally cured at a temperature of 120° C. to 220° C., preferably 140° C. to 200° C., preferably within a period of 10 to 60 minutes at said temperature.

[0130] Another aspect of the present invention is an article of three-dimensional extent, more preferably in sheet form, more particularly in the form of a tape or sheet or patch, comprising, preferably consisting of, the previously mentioned one-component thermosetting epoxy resin composition, in particular for use in reinforcement in cavities of structural components.

[0131] Preferably, as tapes, these articles have a length of 20-500 mm, more preferably 50-250 mm, a width of 2-15 mm, more preferably 5-10 mm and a thickness of 0.5-5 mm, more preferably 1-3 mm.

[0132] Preferably, as patches, these articles have a length and width of 20-500 mm and a thickness of 0.5-5 mm, more preferably 1-3 mm.

[0133] The aforementioned articles are preferably used for the reinforcement of heat-stable materials, more particularly structural components. Heat-stable materials are dimensionally stable at least during the curing process at a curing temperature of 100-220° C., preferably 150-210° C. Particularly heat-stable materials are metals, plastics (such as ABS, polyamides and polyphenylene oxides), polysulfones, polyethersulfones, poly(phenylene oxides) and composite materials (such as sheet molding compounds, unsaturated polyester GRP, composite epoxy materials and composite acrylate materials).

[0134] In preferred applications, the structural component reinforced by the article of the invention is metallic, more particularly the metal has been coated by cathodic electrodeposition (CED).

[0135] A particularly preferred use of the articles of the present invention is in the reinforcement of metals, particularly in body shell structures in the automotive industry. Preferred metals include steel and aluminum. Preferred examples of steel include electrolytically galvanized steel, hot-dip galvanized steel, oiled steel, Bonazinc-coated steel, and subsequently phosphate-treated steel.

[0136] Therefore, a further aspect of the invention is the use of said article for reinforcing thermally stable materials, more particularly structural components.

[0137] Preferably, the reinforced structural component has a thickness of 0.2-1.2 mm, preferably 0.4-1.0 mm and more preferably 0.5 and 0.6 mm.

[0138] The article preferably has self-adhesive properties due to the adhesiveness and can be applied preferably without using any fastening means.The article can be used in particular for reinforcement at locations that are not accessible to welding instruments / robots during assembly due to inaccessibility / narrow constraints.

[0139] Additional fastening means may be employed to secure the article to the surface of the structural component. Preferably, the article has no additional fastening means.

[0140] The expandable article placed inside the structural component foams during heating and, by virtue of the complete chemical curing of the thermosetting epoxy resin composition, it is able to transmit large forces and thus reinforce the structural component.

[0141] Structural components of this type are preferably used in the bodies and / or frames of vehicles and transport vehicles, in particular water or land vehicles or aircraft. The invention preferably includes the use of the reinforcing element according to the invention in the bodies or frames of automobiles (in particular in roofs, hoods, trunk lids and doors), trucks, railway vehicles, boats, ships, helicopters and aircraft, most preferably in automobiles.

[0142] The article is particularly preferably brought into contact with the material to be reinforced, more particularly a structural component, at a temperature between 10°C and 80°C, more particularly between 10°C and 60°C, and then cured at a temperature of typically 140-220°C, more particularly 150-210°C, preferably between 160 and 205°C.

[0143] After curing, the article provides good mechanical properties (especially high lap shear values and good failure modes) to the structural component. The article of the present invention is fully cured when it is subjected to a temperature above the activation temperature of the hardener B. In addition, when cured, the article of the present invention effectively adheres to the surface of the structural component, especially the metal substrate.

[0144] Therefore, another aspect of the present invention relates to a method for reinforcing a structural component, comprising the steps of:

[0145] i) placing the aforementioned one-component thermosetting epoxy resin composition, preferably the aforementioned article, in the cavity of the structural component;

[0146] ii) heating the one-component thermosetting epoxy resin composition, preferably the article, to a temperature of 120° C. to 220° C., preferably 140° C. to 200° C., preferably for 10 to 60 minutes.

[0147] In particular, the present invention comprises a method for reinforcing a structural component, wherein the one-component thermosetting epoxy resin composition is heat-foamable, wherein step i) is followed by step ii).

[0148] The result of the process is a reinforced article. A reinforced article of this type is preferably an automotive or auxiliary automotive component.

[0149] Therefore, another aspect of the present invention relates to the reinforced article obtained by the aforementioned method.

[0150] The present invention is further illustrated below by examples, however, these examples do not limit the present invention in any way. Example

[0151] The test methods used to test various properties in the examples are as follows:

[0152]

[0153]

[0154] Raw materials used

[0155] Preparation of composition

[0156] Based on the information in Tables 1 and 2, reference compositions Ref. 1-Ref. 4 and compositions E1-E5 according to the invention were produced. The amounts in Tables 1 and 2 are in parts by weight. The raw materials used were mixed using a Sigma mixer for 30 minutes. All compositions Ref. 1-Ref. 4 and E1-5 were viscous at 23°C according to the previously described definition.

[0157] The following measurements were performed on the test specimens obtained:

[0158] Test method:

[0159] Needle penetration

[0160] The penetration depth is measured by preparing a square sample (30 mm x 30 mm x 10 mm thick) of the freshly mixed composition. To measure, a 1 mm thin needle is placed on the surface of the sample and released to penetrate the sample for 5 seconds. The total load (weight of the needle and related parts) is 100 g. The penetration depth of the needle is given in 0.1 mm. The measurement is carried out at 23°C. A high penetration value indicates low viscosity of the composition.

[0161] Determination of foam density / volume expansion (expansion rate)

[0162] The expansion stability was tested in all samples by heat treating the individual samples in an oven at different temperatures as shown in Tables 1 and 2. The temperature, time period and degree of expansion (in % based on the original volume before expansion) are shown in Tables 1 and 2.

[0163] The expansion rate of each sample was quantified by measuring the density before and after expansion. The density was determined according to DIN EN ISO 1183 using the immersion method (Archimedes' principle) in deionized water and measuring the mass with a precision balance.

[0164] Tensile shear strength (LSS)

[0165] The determination was carried out in accordance with the general principles of ASTM D1002-10. The following setup (dimensions in mm) was used to determine the tensile shear strength:

[0166] Test temperature: 23℃

[0167] Bonding area: 10mm×20mm

[0168] Adhesive layer thickness: 0.2mm

[0169] Curing: As shown in Table 1 and Table 2

[0170] Test speed: 10mm / min

[0171] Cohesive fracture / adhesive fracture (fracture mode)

[0172] The fracture mode was visually evaluated from the tensile shear strength and classified as CF or AF: CF = cohesive fracture, AF = adhesive fracture.

[0173]

[0174]

Claims

1. A one-component thermosetting epoxy resin composition comprising: - 20 to 55% by weight of at least one epoxy resin A having on average more than one epoxy group per molecule; - 1 to 6% by weight of at least one latent hardener B for an epoxy resin; - 0-3% by weight of at least one accelerator C; - 10 to 50% by weight of at least one impact modifier D; - 0.01-5% by weight of at least one physical or chemical blowing agent E; - 10-35% by weight of fibrous basic magnesium sulfate MOS, wherein the fibrous basic magnesium sulfate MOS is selected from MgSO4.5Mg(OH)2.3H2O and MgSO4.5Mg(OH)2.8H2O, wherein the thermosetting epoxy resin composition has a needle penetration value in units of 0.1 mm of 20-80, measured at 23° C. with a needle thickness of 1 mm using a total load of 100 g for 5 seconds, the total load being the weight of the needle and related parts.

2. The composition according to claim 1, wherein the latent hardener B is selected from the group consisting of dicyandiamide, guanamines, guanidines, substituted ureas, imidazoles and amine complexes.

3. The composition according to claim 1, characterized in that the latent hardener B is aminoguanidine.

4. The composition according to claim 1, characterized in that the latent hardener B is dicyandiamide.

5. Composition according to any one of claims 1 to 4, characterized in that at least one accelerator C is a substituted urea.

6. Composition according to any one of claims 1 to 4, characterized in that the impact modifier D is selected from the group consisting of blocked polyurethane polymers D1, carboxyl-terminated acrylonitrile / butadiene copolymers D2 and liquid rubbers D4.

7. The composition according to any one of claims 1 to 4, characterized in that the impact modifier D is selected from the group consisting of blocked polyurethane polymers D1 and carboxyl-terminated acrylonitrile / butadiene copolymers D2.

8. Composition according to any one of claims 1 to 4, characterised in that the proportion of fibrous basic magnesium sulfate (MOS) is 10 to 30% by weight.

9. The composition according to claim 1, wherein the proportion of fibrous basic magnesium sulfate (MOS) is 10-25% by weight.

10. The composition according to any one of claims 1 to 4, characterized in that the proportion of fibrous basic magnesium sulfate (MOS) is 10 to 20% by weight.

11. The composition according to claim 1, wherein the proportion of fibrous basic magnesium sulfate (MOS) is 10-15% by weight.

12. The composition according to any one of claims 1 to 4, characterized in that the fibrous basic magnesium sulfate (MOS) is MgSO4.5Mg(OH)2.3H2O.

13. The composition according to any one of claims 1 to 4, characterized in that the length of the fibrous basic magnesium sulfate (MOS) is 3 to 1000 μm.

14. The composition according to any one of claims 1 to 4, characterized in that the length of the fibrous basic magnesium sulfate (MOS) is 5 to 100 μm.

15. The composition according to any one of claims 1 to 4, characterized in that the length of the fibrous basic magnesium sulfate (MOS) is 7.5 to 50 μm. 16 . The composition according to claim 1 , wherein the length of the fibrous magnesium sulfate (MOS) is 7.5 to 20 μm.

17. The composition according to any one of claims 1 to 4, characterized in that the diameter of the fibrous basic magnesium sulfate (MOS) is 0.1 to 5 μm.

18. The composition according to any one of claims 1 to 4, characterized in that the diameter of the fibrous basic magnesium sulfate (MOS) is 0.2 to 2 μm.

19. The composition according to any one of claims 1 to 4, characterized in that the diameter of the fibrous magnesium sulfate (MOS) is 0.3 to 1 μm.

20. The composition according to any one of claims 1 to 4, characterized in that the diameter of the fibrous basic magnesium sulfate (MOS) is 0.4 to 0.8 μm.

21. The composition according to any one of claims 1 to 4, characterized in that the thermosetting epoxy resin composition is tacky at 23°C.

22. The composition according to any one of claims 1 to 4, characterized in that when a pressure of 5 kg is applied for 1 second on the surface of the thermosetting epoxy resin composition when pressed with a thumb, the thumb remains stuck to the surface of the thermosetting epoxy resin composition.

23. The composition according to any one of claims 1 to 4, characterized in that the thermosetting epoxy resin composition has a needle penetration value in units of 0.1 mm of 30 to 75, measured at 23°C with a needle thickness of 1 mm using a total load of 100 g for 5 seconds, the total load being the weight of the needle and related parts.

24. The composition according to any one of claims 1 to 4, characterized in that the thermosetting epoxy resin composition has a needle penetration value in units of 0.1 mm of 40 to 70, measured at 23°C with a needle thickness of 1 mm using a total load of 100 g for 5 seconds, the total load being the weight of the needle and related parts.

25. The composition according to any one of claims 1 to 4, characterized in that the thermosetting epoxy resin composition has a needle penetration value in units of 0.1 mm of 50 to 70, measured at 23°C with a needle thickness of 1 mm using a total load of 100 g for 5 seconds, the total load being the weight of the needle and related parts.

26. An article having a three-dimensional extent comprising the one-component thermosetting epoxy resin composition according to any one of claims 1 to 25.

27. The article of claim 26, which has a sheet-like form.

28. The article according to claim 26, in the form of a tape or sheet or patch, wherein as a patch these articles have a length and width of 20-500 mm and a thickness of 0.5-5 mm.

29. The article according to claim 26, which is composed of the one-component thermosetting epoxy resin composition according to any one of claims 1 to 25.

30. The article of claim 28 for use as a reinforcement in a cavity of a structural component.

31. Articles according to claim 28, characterised in that as strips these articles have a length of 20-500 mm, a width of 2-15 mm and a thickness of 0.5-5 mm.

32. Articles according to claim 31, characterised in that, as strips, they have a length of 50-250 mm.

33. Articles according to claim 31, characterised in that, as strips, they have a width of 5-10 mm.

34. Articles according to claim 31, characterised in that as strips they have a thickness of 1-3 mm.

35. Articles according to claim 28, characterised in that as patches these articles have a thickness of 1-3 mm.

36. Use of the article according to any one of claims 26 to 35 for reinforcing a thermally stable material.

37. Use according to claim 36 for reinforcing structural components.

38. A method for reinforcing a structural component, comprising the steps of: i) placing the one-component thermosetting epoxy resin composition according to any one of claims 1 to 25 or the product according to any one of claims 26 to 35 into a cavity of a structural component; ii) heating the one-component thermosetting epoxy resin composition or article to a temperature of 120°C to 220°C.

39. The method of claim 38, wherein in step ii), the one-component thermosetting epoxy resin composition or article is heated to a temperature of 140°C to 200°C.

40. The method according to claim 38 or 39, wherein in step ii), the one-component thermosetting epoxy resin composition or article is heated to the temperature for 10 to 60 minutes.

41. Article obtained by the method according to any one of claims 38 to 40.

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