One-component expandable thermoset epoxy composition with improved storage stability

Abstract

The present invention relates to a one-component thermosetting epoxy resin composition comprising a) at least one epoxy resin A having on average more than one epoxy group per molecule; b) at least one latent hardener for epoxy resins; c) at least one physical or chemical blowing agent BA and d) at least one reaction product RP of at least one acrylonitrile / butadiene rubber ABR containing carboxyl groups with at least one vinyl ether monomer VEM of the general formula CH = CH-O-R, where R is a branched or linear alkyl group having 8 to 16 carbon atoms, preferably a linear alkyl group. Epoxy resin adhesives are notable in that the storage stability is improved, in particular under warm conditions.

Description

Technical Field

[0001] The present invention relates to the field of heat-expandable one-component thermosetting epoxy resin compositions, in particular for producing structural foams and reinforcing elements for hollow structures, comprising such heat-expandable compositions, a process for producing such reinforcing elements, their use for reinforcing hollow structures and a process for reinforcing hollow structures. Prior art

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

[0003] Manufactured products often contain openings and cavities or other hollow components that result from the manufacturing process and / or are designed for other reasons, such as weight reduction. For example, a motor vehicle contains a number of such openings and cavities throughout the vehicle, such as in the vehicle pillars.

[0004] It is often desirable to reinforce such openings and cavities with reinforcing elements built into the openings or cavities in order to strengthen the hollow structure of a manufactured product, such as a vehicle pillar, so that it becomes more resistant to mechanical stresses, but with the advantage of keeping the weight of the hollow structure low.

[0005] These elements for strengthening are usually composed of a carrier made of plastic, metal or other rigid materials and one or more layers of epoxy resin additives attached thereto particularly by injection molding, and when heat or some other physical or chemical forms of energy are introduced, these elements can expand their volume. These parts can also be made of expandable materials completely. Using appropriate structure, reinforcing element can be inserted into the cavity of structure to be enhanced in manufacturing process, but the inwall and / or cavity of structure to be enhanced can be accessible to liquid at the same time. For example, in the manufacturing process of a vehicle, the hollow part of a metal frame can still be covered by electroplating solution to a great extent, and reinforcing element is in place. In the subsequent thermal treatment step, epoxy resin composition expands and reinforcing element fills or strengthens the cavity.

[0006] For example, document US2004 / 0204551 describes a material suitable for reinforcing vehicles in the transportation industry. The material contains an epoxy resin, a curing agent and an epoxy / elastomer adduct, the adduct comprising an epoxy component at least partially reacted with an elastomer, wherein the elastomer comprises nitrile rubber.

[0007] Furthermore, document EP 3885398 A describes a material suitable for reinforcing vehicles in the transport industry, which contains a mixture of epoxy resin, curing agent and epoxy resin / elastomer adduct including nitrile rubber. The epoxy resin adhesive exhibits more constant expansion properties under activation conditions after a storage time of more than 1 month.

[0008] The heat expandable epoxy resin compositions currently used are usually composed of solid epoxy resins. These compositions also contain a blowing agent. Activation of the epoxy resin occurs under activation conditions, such as elevated temperatures, while the blowing agent decomposes and releases gases such as nitrogen or carbon monoxide or physically expands. This results in the above-mentioned volume expansion and the formation of a stable foam, which ideally fills the cavity as intended and adheres to its walls.

[0009] Such heat expandable epoxy resin compositions currently have limited storage stability, which is reflected in a decrease in expansion performance over time under activation conditions.There is a need for heat expandable epoxy resin compositions having improved storage stability. Summary of the invention

[0010] It is therefore an object of the present invention to provide a heat expandable epoxy resin composition having improved storage stability, in particular more constant expansion properties after longer storage times, preferably 3 months or more, at 35° C. under activated conditions.

[0011] Surprisingly, it has been found that this object can be achieved by a one-component thermosetting epoxy composition as defined in claim 1 .

[0012] 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.

[0013] Certain embodiments of the invention

[0014] Therefore, the present invention relates to a one-component thermosetting epoxy resin composition comprising

[0015] a) at least one epoxy resin A having an average of more than one epoxy group per molecule;

[0016] b) at least one latent hardener for the epoxy resin; and

[0017] c) at least one physical or chemical blowing agent BA; and

[0018] d) at least one reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM of the general formula CH═CH—OR, wherein R is a branched or straight-chain alkyl radical having 8 to 16 carbon atoms, preferably a straight-chain alkyl radical.

[0019] The epoxy resin composition is one-component, meaning that the components of the epoxy resin composition, particularly the epoxy resin and the hardener, are present in one component without curing at normal ambient or room temperature. It can therefore be handled in this form, whereas with a two-component system the components are not mixed until immediately prior to use.

[0020] The curing of the one-component epoxy resin composition is accomplished by heating, usually at a temperature greater than 70°C, preferably 100-220°C.

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

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

[0023] The dashed lines in the formulae herein represent in each case the bond between the substituent in question and the relevant remainder of the molecule.

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

[0025] The thermosetting one-component epoxy resin composition comprises at least one epoxy resin A having an average of more than one epoxy group per molecule. The epoxy groups are preferably in the form of glycidyl ether groups.

[0026] The proportion of epoxy resin A having more than one epoxide group per molecule is preferably 30-90% by weight, 35-85% by weight, 40-75% by weight, more preferably 45-60% by weight, based on the total weight of the one-component heat-curing epoxy resin composition.

[0027] The epoxy resin A having more than one epoxy group per molecule on average is preferably a liquid epoxy resin or a solid epoxy resin, more preferably a solid epoxy resin. The term "solid epoxy resin" is very familiar 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 higher than room temperature, which means that they can be crushed into pourable powders at room temperature. Preferably more than 70% by weight, more preferably more than 80% by weight, more than 90% by weight, more than 95% by weight, more than 98% by weight of the epoxy resin A is a solid epoxy resin.

[0028] Preferred epoxy resins have the formula (II)

[0029]

[0030] In this formula, the substituents R' and R" are independently H or CH3.

[0031] In solid epoxy resins, the index s has a value >1.5, more particularly 2 to 12.

[0032] Such solid epoxy resins are commercially available from, for example, Dow or Huntsman or Hexion.

[0033] Compounds of formula (II) having an index s of 1 to 1.5 are referred to by those skilled in the art as semisolid epoxy resins. For the purposes of the present invention, they are likewise considered to be solid resins. However, preferred solid epoxy resins are epoxy resins in a narrower sense, in other words those in which the index s has a value >1.5.

[0034] In the case of liquid epoxy resins, the index s has a value of less than 1. Preferably, the value of s is less than 0.2.

[0035] Thus, the resin is preferably diglycidyl ether of bisphenol A (DGEBA), bisphenol F and bisphenol A / F. These types of liquid resins can be used, for example, in the form of GY 250, PY 304, GY 282 (Huntsman) or DER TM 331 or DER TM 330 (Dow) or Epikote 828 (Hexion).

[0036] Also suitable as epoxy resins A are so-called epoxy novolacs. These compounds have, in particular, the following formula: in or CH2, R1=H or methyl and z=0-7.

[0037] More particularly, these are phenol-epoxy or cresol-epoxy novolacs (R2═CH2).

[0038] 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 TM Commercially available from Dow Chemical.

[0039] The epoxy resin A is preferably a solid epoxy resin of formula (II).

[0040] The thermosetting one-component epoxy resin composition also contains at least one latent hardener for epoxy resin. The latent hardener is substantially inert at room temperature and is activated by elevated temperature, typically at 70° C. or higher, to initiate the curing reaction. Conventional latent hardeners for epoxy resins can be used. Nitrogen-containing latent epoxy resin hardeners are preferred.

[0041] The latent hardener is preferably selected from dicyandiamide, guanamine, guanidine, aminoguanidine and derivatives thereof, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide.

[0042] The latent hardener 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.

[0043] The proportion of the latent hardener is preferably 0.1 to 15% by weight, more preferably 0.2 to 5% by weight, very particularly 0.5-3% by weight, based on the total weight of the epoxy resin composition.

[0044] The at least one reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM is preferably a reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM reacted at a temperature of 23°C to 100°C, preferably 30°C to 80°C, more preferably 40°C to 60°C for 10 to 120 min, preferably 30 to 75 min, more preferably 45 to 75 min.

[0045] Surprisingly it was found that the time and temperature ranges described lead to little color and texture change and good properties of the reaction product compared to unreacted acrylonitrile / butadiene rubber ABR.

[0046] Preferably, the molecular sieve is present during the reaction and / or added after the reaction. Preferably, the molecular sieve is selected from natural and synthetic zeolites. Preferably, the molecular sieve is present in an amount of 2-10 wt %, preferably 4-8 wt %, based on the total amount of acrylonitrile / butadiene rubber ABR used for the reaction.

[0047] Surprisingly, it was found that the reaction product RP has a significantly reduced reduction in expansion properties compared to unreacted carboxyl-containing acrylonitrile / butadiene rubbers under activated conditions after a longer storage time, preferably after a storage time of more than 1 month at 35° C. / 50% humidity, more preferably after a storage time of 3 months at 35° C. / 50%. This is clearly seen in Table 1, for example in the comparison of E-1 with Ref. 1 and Ref. 2 or in the comparison of E-2 with Ref. 3 and Ref. 4.

[0048] Based on the total weight of the one-component thermosetting epoxy resin composition, the composition preferably contains 5 to 40 wt %, preferably 10 to 30 wt %, more preferably 15 to 25 wt % of the reaction product RP.

[0049] Preferably, the carboxyl-containing acrylonitrile / butadiene rubber ABR is reacted with at least one vinyl ether monomer VEM in a molar ratio of vinyl ether groups to carboxyl groups of 3:1 to 1:1, preferably 2.5:1 to 1.5:1, more preferably 2.2:1 to 1.8:1.

[0050] At least the vinyl ether monomer VEM has the general formula CH=CH-OR, wherein R is a branched or straight-chain alkyl group having 8 to 16 carbon atoms, preferably a straight-chain alkyl group.

[0051] Preferred are vinyl ether monomers VEM of the general formula CH=CH-OR, in which R is a straight-chain alkyl group having 8 to 16 carbon atoms, preferably 10 to 14 carbon atoms, more preferably 12 carbon atoms.

[0052] Preferably, the vinyl ether monomer VEM is selected from octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether (DDVE), tetradecyl vinyl ether and hexadecyl vinyl ether, preferably from decyl vinyl ether, dodecyl vinyl ether (DDVE) and tetradecyl vinyl ether, more preferably dodecyl vinyl ether (DDVE). These are available from suppliers such as BASF and Aldrich.

[0053] Surprisingly, it was found that the reaction products with vinyl ether monomers having R with more than 16 carbon atoms under activated conditions do not lead to a significantly reduced reduction in the swelling properties after a longer storage time. This is evident in Table 1, for example in the comparison of E-1 with Ref. 2 or in the comparison of E-2 with Ref. 4.

[0054] The at least one acrylonitrile / butadiene rubber ABR containing carboxyl groups (eg, carboxylic acid groups) may further include pendant carboxyl groups or carboxyl groups.

[0055] The carboxyl group-containing acrylonitrile / butadiene rubber ABR preferably has a carboxyl group content of 0.005 equivalents per hundred rubber (EPHR) to 0.4 EPHR, more preferably 0.01 EPHR to 0.2 EPHR, even more preferably 0.05 EPHR to 0.1 EPHR.

[0056] For the acrylonitrile / butadiene rubber ABR containing carboxyl groups, the carboxyl groups are preferably provided by a third monomer such as methacrylic acid. The acrylonitrile / butadiene rubber ABR containing carboxyl groups is preferably acrylonitrile / butadiene / methacrylic acid rubber.

[0057] A particularly preferred carboxyl-containing acrylonitrile / butadiene rubber ABR is available from Nippon Zeon under the trade name Hycar, currently available under the trade name NIPOL.

[0058] The carboxyl-containing acrylonitrile / butadiene rubber ABR preferably comprises 10% to 50% by weight of nitrile, more preferably 20% to 40% by weight of nitrile, even more preferably 25% to 35% by weight of nitrile.

[0059] The carboxyl-containing acrylonitrile / butadiene rubber ABR preferably has a Mooney viscosity (ML 1+4 at 100° C.) of 20-60 MU (Mooney units). Mooney viscosity refers to the viscosity measurement of rubber. It is defined as the shear torque that resists the rotation of a cylindrical metal disk (or rotor) embedded in the rubber in a cylindrical cavity. The dimensions of the shear disk viscometer, the test temperature and the steps for determining the Mooney viscosity are preferably defined in the ASTM D 1646 standard.

[0060] It may be preferred that the carboxyl-containing acrylonitrile / butadiene rubber ABR used for the reaction product RP has a Mooney viscosity (ML 1+4, 100° C.) of 20-34 MU (Mooney units). This is advantageous for higher compressive strength values. This can be seen in Table 1, for example, in the comparison of E-1 with E-2.

[0061] It may also be preferred if the carboxyl-containing acrylonitrile / butadiene rubber ABR used for the reaction product RP has a Mooney viscosity (ML 1+4, 100° C.) of 35-60 MU (Mooney units). This is advantageous for higher expansion values. This can be seen in Table 1, for example, in the comparison of E-1 with E-2.

[0062] The one-component thermosetting epoxy resin composition may further comprise at least one toughness improver D. The toughness improver D may be solid or liquid. More particularly, the toughness improver D is selected from a polyurethane polymer D1 with a blocked end, a liquid rubber D2, and a core-shell polymer D3. Preferably, the additional toughness improver D is selected from a polyurethane polymer D1 with a blocked end and a liquid rubber D2. The aforementioned liquid rubber D2 is different from the acrylonitrile / butadiene rubber ABR containing a carboxyl group.

[0063] The proportion of toughness improver D is preferably 1-10% by weight, more preferably 2.5-7.5% by weight, based on the total weight of the epoxy resin composition. It may also be preferred if the epoxy resin composition contains less than 2, preferably less than 1, less than 0.5, less than 0.1, and most preferably no toughness improver D as described above.

[0064] In a preferred embodiment, the one-component heat-curable epoxy resin composition further comprises at least one filler F. Preferred are mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated or ground), dolomite, quartz, silicon dioxide (fumed or precipitated), cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic beads, hollow glass beads, hollow organic beads, glass beads, glass or carbon fibers and color pigments. Particularly preferred are fillers selected from calcium carbonate, calcium oxide, talc, glass or carbon fibers and fumed silica, more preferably talc, glass or carbon fibers and fumed silica.

[0065] The total proportion of the total filler F is advantageously 5 to 50% by weight, preferably 15 to 40% by weight, 20 to 35% by weight, based on the total weight of the epoxy resin composition.

[0066] One-component thermosetting epoxy resin compositions may contain further ingredients, especially catalysts, thixotropic agents, plasticizers, solvents, dyes and pigments, corrosion inhibitors, surfactants, defoamers and adhesion promoters.

[0067] The one-component, heat-curable epoxy resin composition comprises at least one physical or chemical blowing agent BA.

[0068] Chemical foaming agents are organic or inorganic substances that form or split gaseous substances under the influence of temperature, humidity, electromagnetic radiation or chemicals. Such substances are particularly azodicarbonamide, sulfonyl hydrazide, bicarbonate or carbonate. Compounds can be used as physical foaming agents, which, for example, when temperature, pressure or volume changes, particularly when temperature rises, change to the gaseous state of the substance and therefore form a foam structure 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 the composition in microencapsulated form. Both chemical and physical foaming agents can produce foam structures in polymer compositions.

[0069] 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.

[0070] The at least one physical or chemical blowing agent BA preferably has an activation temperature of 120°C to 220°C, preferably 140°C to 200°C.

[0071] The proportion of the blowing agent BA is advantageously 0.1 to 7.5% by weight, preferably 0.5 to 5% by weight and in particular 1 to 4% by weight, based on the total weight of the epoxy resin composition.

[0072] The one-component thermosetting epoxy resin composition may also contain one or more additives. Examples of additives that may be used are processing aids, such as waxes, antioxidants, UV stabilizers, dyes, biocides or flame retardants.

[0073] 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.

[0074] The one-component thermosetting epoxy resin composition preferably has a melt flow index (MFI) of 0.5-15 g / 10 min, particularly 1-10 g / 10 min, preferably 1-5 g / 10 min, most preferably 1-3 g / 10 min.

[0075] MFI is measured according to ASTM D1238 at 110°C and 2.16 kg, and preferably the melting time is 120 seconds.

[0076] The one-component thermosetting epoxy resin composition is preferably an injection moldable mixture, ie the mixture has a viscosity suitable for injection molding at the processing temperature. It is particularly injection moldable without foaming.

[0077] A particularly preferred thermosetting one-component epoxy resin composition comprises:

[0078] - 30-90 wt. %, 35-85 wt. %, 40-75 wt. %, more preferably 45-60 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;

[0079] - 0.1 to 15 wt. %, more preferably 0.2 to 5 wt. %, more particularly 0.5 to 3 wt. %, of at least one latent hardener for epoxy resins, more particularly dicyandiamide, based on the total weight of the one-component thermosetting epoxy resin composition;

[0080] 0.1 to 7.5% by weight, preferably 0.5 to 5% by weight, in particular 1 to 4% by weight, of a blowing agent BA, based on the total weight of the epoxy resin composition;

[0081] 5 to 40% by weight, preferably 10 to 30% by weight, more preferably 15 to 25% by weight, of at least one reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM of the general formula CH═CH—OR, in which R is a branched or linear alkyl radical, preferably a linear alkyl radical, having 8 to 16 carbon atoms, based on the total amount of epoxy resin A;

[0082] - Based on the total weight of the epoxy resin composition, preferably 5-40 wt%, preferably 20-40 wt% of filler F, the filler F being selected from the group consisting of calcium carbonate, calcium oxide, talc, glass fiber and fumed silica, more preferably talc, glass fiber and fumed silica.

[0083] It may further be advantageous if the preferred one-component thermosetting epoxy resin composition consists of the abovementioned components to an extent 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, based on the total weight of the epoxy resin composition.

[0084] The one-component thermosetting epoxy resin composition is preferably tack-free at 23° C. The term “tack-free” is understood herein to mean instant tack or “stickiness” which is so low at 23° C. that when a thumb is pressed on the surface of the one-component thermosetting epoxy resin composition with a pressure of about 5 kg for 1 second, the thumb does not adhere to the surface of the composition layer, or the one-component thermosetting epoxy resin composition cannot be lifted.

[0085] 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.

[0086] After mixing, the resulting composition can be molded into its desired shape, for example, by extrusion, blow molding, pelletizing, injection molding, compression molding, stamping or punching, or any other suitable method.

[0087] The mixing of the components preferably includes an extrusion step, and the mixed and extruded composition is then pelletized. The pelletized composition is then preferably formed into its desired shape by injection molding.

[0088] 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 is cured only when the foaming of the epoxy resin composition has occurred in large quantities. Otherwise, the epoxy resin composition will harden before it has reached the desired position by 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.

[0089] Preferably, the expandable epoxy resin composition shows the following reduction in expansion after storage at 35°C for 3 months under activated conditions compared to the expansion of the expandable epoxy resin composition immediately after preparation of the composition (measured as described in the experimental part):

[0090] - Expansion at 180°C for 30 minutes: less than 25%, preferably less than 15%, more preferably less than 5%.

[0091] It is further preferred that the expandable epoxy resin composition exhibits the following adhesion and mechanical properties (preferably measured according to the experimental part):

[0092] -LSS, baked on HDG at 180°C for 30 minutes: ≥1.5MPa, preferably ≥1.75MPa, more preferably ≥2MPa; and / or, preferably and

[0093] - Compression strength: ≥5MPa, preferably ≥6MPa, more preferably ≥6MPa.

[0094] Another aspect of the invention is a reinforcing element comprising a one-component heat-curing epoxy resin composition, in particular for reinforcement in a cavity of a structural component.

[0095] The one-component thermosetting epoxy resin composition is preferably applied or attached to the carrier component.

[0096] The carrier part can consist of any material. Preferred materials are plastics, in particular polyurethanes, polyamides, polyesters and polyolefins, preferably high temperature resistant polymers such as poly(phenylene ether), polysulfone or polyethersulfone, which are also foamed, metals, in particular aluminum and steel, or any combination of these materials.

[0097] Furthermore, the carrier component can have any structure and configuration. For example, it can be solid or hollow or have a grid-like structure. The surface of the carrier component can generally be smooth, rough or structured. In addition to its function as a carrier of the foamable material, the carrier component can also contribute to structural reinforcement.

[0098] The reinforcing element can also have no carrier part and consist completely of a one-component, heat-curing epoxy resin composition.

[0099] The reinforcing element comprising the carrier part and the one-component heat-curing epoxy resin composition is preferably produced by injection molding.

[0100] If the carrier part consists of a material that can be processed by injection molding, a two-component injection molding process is usually used. First, the first component (in this case the carrier part) is injected. After the first component has cured, the cavity in the mold is enlarged or adjusted, or the molded part is placed in a new mold, and the second component (in this case the epoxy resin composition) is molded onto the first component using a second injection unit.

[0101] If the carrier component consists of a material that cannot be produced by an injection molding process (eg metal), the carrier component is placed in a suitable tool and the epoxy resin composition is injection molded onto the carrier component.

[0102] Of course, the epoxy resin composition may also be fastened to the carrier member by any other fastening means or method.

[0103] For the reinforcing elements mentioned, it is further advantageous if the epoxy resin composition can be foamed and thermally cured at a temperature of 120 to 220° C., preferably 140 to 200° C., preferably within a period of 10 to 60 minutes at said temperature.

[0104] Furthermore, the invention comprises the use of a reinforcing element as described above to strengthen a cavity in a structural component. Structural components of this type are preferably used in the body and / or frame of transport and transportation vehicles, in particular in the body and / or frame of a vehicle or aircraft on water or land. The invention preferably comprises the use of a reinforcing element according to the invention in the body or frame of a car (in particular A, B, C or D pillar), a truck, a rail car, a ship, a boat, a helicopter and an aircraft, most preferably in a car.

[0105] Therefore, another aspect of the invention relates to a method for reinforcing a structural component, comprising the following steps:

[0106] i) placing the reinforcing element in the cavity according to the previous description;

[0107] ii) heating the reinforcing element to a temperature of 120° C. to 220° C., preferably 140° C. to 200° C., preferably for 10 to 60 minutes.

[0108] Preferably, step i) is performed before step ii).

[0109] The present invention is further illustrated below by examples, however, these examples are not intended to limit the present invention in any way. Example

[0110] The raw materials and test methods used to test the corresponding properties in the examples are as follows:

[0111]

[0112]

[0113] Raw materials used

[0114] Preparation of reaction products (REF-RP1, REF-RP2, RP1 and RP2)

[0115] 150 g of ABR1, 150 g of ABR2 were mixed with 35.84 g of DDVE, 45 g of ODVE respectively in the presence of 0.15 g of 2-ethylhexyl phosphate in a Brabender mixer at 35 rpm for 50 minutes at 50° C. Once conversion was confirmed by FTIR, 9.3 g of molecular sieves (zeolite) were added.

[0116] REF-RP1: Reaction product of ABR1 and ODVE

[0117] Ref-RP2: Reaction product of ABR2 and ODVE

[0118] RP1: Reaction product of ABR1 and DDVE

[0119] RP2: Reaction product of ABR2 and DDVE

[0120] Preparation of composition

[0121] Reference compositions Ref. 1 to Ref. 4 and compositions E-1 and E-2 according to the invention were prepared according to the information in Table 1. The amounts in Table 1 are in % by weight.

[0122] The raw materials used were mixed with a Brabender mixer (CW Brabender Prep-mixer Model RS 7500) at 90° C. for 20 minutes. The resulting composition was then compressed into 3-4 mm thick sheets using a heated hydraulic press at 80° C. These sheets were then cut into the desired size for evaluation testing.

[0123] The following measurements were performed on the obtained samples:

[0124] Viscosity measurement

[0125] The viscosity measurements of compositions Ref.1-Ref.4, E-1 and E-2 were performed on an Anton Paar Modular Compact rheometer. The set temperature was 110°C, the frequency was 20 rad / s, and the strain was 3%. The sample size was 1 inch diameter and the thickness was 3-5 mm.

[0126] Determination of foam density / volume expansion (expansion rate)

[0127] As described above, the composition was pressed into a sheet 3-4 mm thick directly after production. The sheet was cut into plagues 3 mm x 12 mm. These plagues were quantitatively tested directly after production (initial) or after being placed in a humidity chamber at 35°C / 50% humidity for 3 months (35°C / 50% humidity for 3 months).

[0128] The volume expansion of each sample was quantified by measuring the density before and after expansion. The density was determined using the immersion method in deionized water (Archimedes principle) and a precision balance for measuring mass according to DIN EN ISO 1183. The expansion was determined by oven-baking the sample at 180°C for 30 minutes.

[0129] The volume expansion is quantified after preparation of the composition (initial) and directly afterwards.

[0130] Before expansion, all compositions Ref. 1 to Ref. 4, E-1 and E-2 were tack-free at 23° C. according to the above definition.

[0131] Adhesion force (LSS) determination

[0132] Adhesion strength was determined based on SAE J1523. Oil-coated HDG plates (25 mm wide, 100 mm long and 1 mm thick) were used. The composition material with a size of 25×25×3 mm was placed between them. After the specimen was clamped in place, the specimen was baked at 180°C for 30 minutes. A tensile tester (Zwick) was used with a speed of 10 mm / min.

[0133] Determination of compressive strength of expansive materials

[0134] To determine the compressive strength properties, the uncured material was placed in a cylindrical tube lined with release paper with an inner diameter of 30 + / - 2 mm according to ASTM D1621 and cured for 30 minutes after the material reached 180°C.

[0135] After baking, the material was ground until the remaining specimen was 30 mm in diameter x 60 mm in height. After conditioning at 23°C for 24 hours, the cylinder was placed between two compression plates and the test was started at a speed of 10 mm / min to 30% strain. The compressive strength was recorded.

[0136]

[0137]

[0138] Table 1.

Claims

1. A one-component thermosetting epoxy resin composition comprising: a) at least one epoxy resin A having an average of more than one epoxy group per molecule; b) at least one latent hardener for the epoxy resin; and c) at least one physical or chemical blowing agent BA; and d) at least one reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM of the general formula CH═CH—OR, wherein R is a branched or straight-chain alkyl radical having 8 to 16 carbon atoms, preferably a straight-chain alkyl radical.

2. The one-component heat-curable epoxy resin composition according to claim 1, wherein the proportion of the epoxy resin A having more than one epoxy group per molecule on average is 30-90% by weight, 35-85% by weight, 40-75% by weight, more preferably 45-60% by weight, based on the total weight of the one-component heat-curable epoxy resin composition. 3 . The one-component thermosetting epoxy resin composition according to claim 1 , wherein the epoxy resin A is a solid epoxy resin.

4. The one-component thermosetting epoxy resin composition according to any one of the preceding claims, wherein the at least one carboxyl-containing acrylonitrile / butadiene rubber ABR has a carboxyl content of 0.005 equivalents per hundred rubber (EPHR) to 0.4 EPHR, more preferably 0.01 EPHR to 0.2 EPHR, even more preferably 0.05 EPHR to 0.1 EPHR.

5. The one-component thermosetting epoxy resin composition according to any one of the preceding claims, wherein the at least one carboxyl-containing acrylonitrile / butadiene rubber ABR comprises 20 to 40% by weight of nitrile, preferably 25 to 35% by weight of nitrile.

6. A one-component, thermosetting epoxy resin composition according to any one of the preceding claims, wherein the at least one vinyl ether monomer VEM is selected from octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether (DDVE), tetradecyl vinyl ether and hexadecyl vinyl ether, preferably from decyl vinyl ether, dodecyl vinyl ether (DDVE) and tetradecyl vinyl ether, more preferably dodecyl vinyl ether (DDVE).

7. The one-component thermosetting epoxy resin composition according to any one of the preceding claims, wherein the at least one reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM is preferably a reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM at a temperature of 23° C. to 100° C., preferably 30° C. to 80° C., more preferably 40° C. to 60° C., for 10 to 120 minutes, preferably 30 to 75 minutes, more preferably 45 to 75 minutes.

8. The one-component thermosetting epoxy resin composition according to claim 7, wherein the carboxyl-containing acrylonitrile / butadiene rubber ABR is reacted with the at least one vinyl ether monomer VEM in a ratio of vinyl ether group to carboxyl group of 3:1 to 1:1, preferably 2.5:1 to 1.5:1, more preferably 2.2:1 to 1.8:

1.

9. A one-component, heat-curable epoxy resin composition according to any one of the preceding claims, wherein the proportion of the at least one reaction product RP of at least one carboxyl-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM of the general formula CH═CH—OR is 5 to 40% by weight, preferably 10 to 30% by weight, more preferably 15 to 25% by weight, based on the total amount of epoxy resin A, wherein R is a branched or linear alkyl group having 8 to 16 carbon atoms, preferably a linear alkyl group.

10. A one-component thermosetting epoxy resin composition according to any one of the preceding claims, wherein the latent hardener is selected from dicyandiamide, guanamine, guanidine, aminoguanidine and its derivatives, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide.

11. The one-component heat-curable epoxy resin composition according to any one of the preceding claims, wherein the one-component heat-curable epoxy resin composition further comprises at least one filler F selected from calcium carbonate, calcium oxide, talc, glass fiber and fumed silica, more preferably talc, glass fiber and fumed silica.

12. The one-component, heat-curing epoxy resin composition according to claim 1, wherein the proportion of the blowing agent BA is 0.1 to 7.5% by weight, preferably 0.5 to 5% by weight, in particular 1 to 4% by weight, based on the total weight of the epoxy resin composition.

13. The one-component thermosetting epoxy resin composition according to any one of the preceding claims, wherein the one-component thermosetting epoxy resin composition has a melt flow index (MFI) of 0.5-15 g / 10 min, particularly 1-10 g / 10 min, preferably 1-5 g / 10 min, most preferably 1-3 g / 10 min, measured at 110° C., 2.16 kg according to ASTM D1238.

14. The one-component thermosetting epoxy resin composition according to any one of the preceding claims, wherein the one-component thermosetting epoxy resin composition is tack-free at 23°C.

15. A reinforcing element comprising a one-component, heat-curing epoxy resin composition according to claims 1 to 14, in particular for reinforcement in cavities of structural components, preferably in bodies and / or frames of vehicles and transport.

16. A method for reinforcing a structural component, comprising the steps of: i) placing a reinforcing element according to claim 15 in a cavity of a structural component, preferably in the body and / or frame of a carrying and transport vehicle; ii) heating the reinforcing element to a temperature of 120° C. to 220° C., preferably 140° C. to 200° C., preferably for 10 to 60 minutes.

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