One-component expandable thermosetting epoxy composition having 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 epoxide group per molecule; b) at least one latent curing agent for the epoxy resin; c) at least one physical or chemical blowing agent BA; d) at least one carboxyl group-containing acrylonitrile / butadiene rubber ABR; and at least one reaction product RP of at least one vinyl ether monomer VEM of the general formula CH=CH-O-R, wherein R is a branched or linear alkyl group having between 8 and 16 carbon atoms, preferably a linear alkyl group. This epoxy resin adhesive is noted for its improved storage stability, particularly under warm conditions.

Description

Technical Field

[0001] The present invention relates in particular to a thermally expandable one-component thermosetting epoxy resin composition for producing a structural foam, and a reinforcing element for a hollow structure comprising such a thermally expandable composition, a method for producing such a reinforcing element, their use for reinforcing a hollow structure, and a method for reinforcing a hollow structure.

Background Art

[0002] One important field of use of thermally expandable thermosetting epoxy resin additives has been found particularly in vehicle assembly, when foaming cavities in a white body.

[0003] Industrial products often result from the manufacturing process and / or contain openings and cavities or other hollow parts designed for another reason, such as weight reduction. Motor vehicles, for example, contain several such openings and cavities, for example in vehicle pillars, throughout the vehicle.

[0004] It is often desirable to reinforce such openings and cavities by means of a reinforcing element incorporated into the opening or cavity to reinforce a hollow structure of an industrial product, such as a vehicle pillar, which has the advantage that the resistance to mechanical stress is increased while maintaining the low weight of the hollow structure.

[0005] Such elements, which are often used for reinforcement and consist of a carrier made of plastic, metal, or another rigid material and one or more layers of epoxy resin additives attached thereto, particularly by injection molding, can expand their volume when heat or some other physical or chemical form of energy is introduced. Such components can also consist entirely of expandable materials. With an appropriate configuration, the reinforcement elements can be inserted into the cavities of the structure to be reinforced during the manufacturing process, while at the same time allowing a liquid to reach the inner walls of the structure to be reinforced and / or the cavities. For example, during the manufacturing process of a vehicle, the reinforcement elements are already in place, but the hollow parts of the metal frame can still be mostly covered by the liquid of the electrocoating. During a subsequent heat treatment step, the epoxy resin composition expands and the reinforcement elements fill or reinforce the cavities.

[0006] For example, U.S. Patent Application Publication No. 2004 / 0204551 in the literature describes materials suitable for vehicle reinforcement in the transportation industry. The above materials include an epoxy resin, a curing agent, and an epoxy / elastomer adduct containing an epoxy component that at least partially reacts with the elastomer, and the above elastomer contains an epoxy / elastomer adduct containing butadiene acrylonitrile rubber.

[0007] Furthermore, European Patent Application Publication No. 3885398 A in the literature describes materials suitable for vehicle reinforcement in the transportation industry, including an epoxy resin, a curing agent, and a mixture of an epoxy / elastomer adduct containing butadiene acrylonitrile rubber. This epoxy resin adhesive exhibits more consistent expansion characteristics under activation conditions after a storage time exceeding one month.

[0008] Currently used thermally expandable epoxy resin compositions often consist of solid epoxy resins. These compositions also contain a blowing agent. Activation of the epoxy resin occurs under activation conditions such as high temperature, and at the same time, the blowing agent decomposes to release a gas such as nitrogen or carbon monoxide, or expands physically. This causes the aforementioned volume expansion, forming a stable foam which ideally fills the cavity as intended and adheres to its walls.

[0009] Such thermally expandable epoxy resin compositions currently have limited storage stability, which is reflected by the fact that the expansion characteristics under activation conditions decrease over time. There is a need for thermally expandable epoxy resin compositions with improved storage stability.

Summary of the Invention

Problems to be Solved by the Invention

[0010] Therefore, one object of the present invention is to provide a thermally expandable epoxy resin composition having improved storage stability, and in particular, having more constant expansion characteristics under activation conditions after a longer storage time, preferably after 3 months or more at 35°C.

Means for Solving the Problems

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

[0012] Further aspects of the invention are the subject of further independent claims. Particularly preferred embodiments of the invention are the subject of the dependent claims.

Modes for Carrying Out the Invention

[0013] Therefore, the present invention provides a) at least one epoxy resin A having on average more than one epoxide group per molecule; b) at least one latent curing agent for the epoxy resin; c) at least one physical or chemical blowing agent BA; d) at least one reaction product RP of at least one carboxyl group-containing acrylonitrile / butadiene rubber ABR and 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 between 8 and 16 carbon atoms, preferably a linear alkyl group; It relates to a one-component thermosetting epoxy resin composition containing the following.

[0014] The above epoxy resin composition is of the one-component type, which means that the components of the epoxy resin composition, particularly the epoxy resin and the curing agent, are present in one component and curing does not occur at normal ambient temperature or room temperature. Therefore, it can be handled in this form, while in a two-component system, those components cannot be mixed until immediately before use.

[0015] Curing of the one-component epoxy resin composition is typically achieved by heating at a temperature above 70 °C, preferably in the range of 100 - 220 °C.

[0016] The prefix "poly" in expressions such as polyol or polyisocyanate means that the compound has two or more of the described groups. For example, a polyisocyanate is a compound having two or more isocyanates.

[0017] The expression "independently of one another" used hereinafter means that two or more substituents of the same designation in the same molecule can have the same or different meanings according to the definition.

[0018] The dashed lines in the formulas in this document represent the bonds between the respective substituents and the remaining part of the molecule in each case.

[0019] Unless otherwise specified, room temperature in this specification means a temperature of 23 °C.

[0020] The thermosetting one-component epoxy resin composition contains at least one epoxy resin A having on average more than one epoxide group per molecule. The epoxide group is preferably in the form of a glycidyl ether group.

[0021] The proportion of the epoxy resin A having on average more than one epoxide group per molecule is preferably 30 to 90% by weight, 35 to 85% by weight, 40 to 75% by weight, more preferably 45 to 60% by weight, based on the total weight of the one-component thermosetting epoxy resin composition.

[0022] The epoxy resin A having on average more than one epoxide group per molecule is preferably a liquid epoxy resin or a solid epoxy resin, more preferably 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 resin". The glass transition temperature of the solid resin is higher than room temperature, which means that they can be pulverized into a flowable powder at room temperature. It is preferred that more than 70% by weight, more preferably more than 80% by weight, more preferably more than 90% by weight, more preferably more than 95% by weight, more preferably more than 98% by weight of the epoxy resin A is a solid epoxy resin.

[0023] A preferred epoxy resin has the formula (II)

Chemical formula

[0024] In this formula, the substituents R' and R'' are, independently of each other, either H or CH 3 either.

[0025] In the solid epoxy resin, the index s has a value of >1.5, especially 2 to 12.

[0026] This type of solid epoxy resin is commercially available, for example, from Dow or Huntsman or Hexion.

[0027] Compounds of formula (II) having an exponent s of from 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, these are considered to be the same as solid resins. However, preferred solid epoxy resins are epoxy resins in the narrower sense, i.e. epoxy resins having an exponent s with a value > 1.5.

[0028] In the case of liquid epoxy resins, the exponent s has a value of less than 1. Preferably s has a value of less than 0.2.

[0029] Thus, the resins in question are preferably the diglycidyl ethers of bisphenol A (DGEBA), the diglycidyl ethers of bisphenol F, and furthermore the diglycidyl ethers of bisphenol A / F. Liquid resins of these types are available, for example, as Araldite® GY 250, Araldite® PY 304, Araldite® GY 282 (Huntsman), or D.E.R.® 331 or D.E.R.® 330 (Dow), or Epikote 828 (Hexion).

[0030] Even more suitable as epoxy resin A are those known as epoxy novolacs. These compounds have, in particular, the following formula:

Chemical formula

Chemical formula

[0031] In particular, these are phenol-epoxy or cresol-epoxy novolacs (R2 = CH 2 ).

[0032] These types of epoxy resins are commercially available under the trade names EPN or ECN and Tactix® from Huntsman, or the product series D.E.N.® from Dow Chemical.

[0033] Epoxy resin A is preferably a solid epoxy resin of formula (II).

[0034] The thermosetting one-component epoxy resin composition further comprises at least one latent curing agent for the epoxy resin. The latent curing agent is substantially inert at room temperature and is activated at elevated temperatures, typically at temperatures of 70 °C or higher, thereby initiating the curing reaction. Conventional latent curing agents for epoxy resins can be used. Latent epoxy resin curing agents containing nitrogen are preferred.

[0035] The latent curing agent is preferably selected from dicyandiamide, guanamine, guanidine, aminoguanidine, and their derivatives, substituted ureas, imidazoles, and amine complexes, and is preferably selected from dicyandiamide.

[0036] The latent curing agent is preferably used in a stoichiometric amount based on the epoxy groups in the composition. The molar ratio of epoxy groups to the active hydrogen of the latent curing agent is preferably 0.8 to 1.2, particularly 0.9 to 1.1, and preferably 0.95 to 1.05.

[0037] The proportion of the latent curing agent is preferably 0.1 to 15% by weight, more preferably 0.2 to 5% by weight, and particularly 0.5 to 3% by weight, based on the total weight of the epoxy resin composition.

[0038] At least one reaction product RP of at least one carboxyl group-containing acrylonitrile / butadiene rubber ABR and at least one vinyl ether monomer VEM is preferably obtained by reacting an acrylonitrile / butadiene rubber ABR containing at least one carboxyl group with 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.

[0039] Surprisingly, it has been found that within the above time and temperature ranges, there are almost no changes in color and texture, and the performance of the reaction product is better than that of the unreacted acrylonitrile / butadiene rubber ABR.

[0040] Preferably, molecular sieves are present during the reaction and / or added after the reaction. Preferably, the molecular sieves are selected from the group consisting of natural and synthetic zeolites. Preferably, the molecular sieves are present in an amount of 2 to 10% by weight, preferably 4 to 8% by weight, based on the total amount of acrylonitrile / butadiene rubber ABR used in the reaction.

[0041] Surprisingly, compared with the unreacted carboxyl group-containing acrylonitrile / butadiene rubber, the above reaction product RP shows a significant reduction in the decrease of the swelling characteristics under activation conditions after a longer storage time, preferably after a storage time exceeding one month at 35°C / 50% humidity, more preferably after a storage time of three months at 35°C / 50%. This is evident from the comparison in Table 1, for example, between E-1 and Ref.1 and Ref.2, or between E-2 and Ref.3 and Ref.4.

[0042] The above composition preferably contains 5 to 40% by weight, preferably 10 to 30% by weight, more preferably 15 to 25% by weight of the reaction product RP based on the total weight of the one-component thermosetting epoxy resin composition.

[0043] Preferably, the carboxyl group-containing acrylonitrile / butadiene rubber ABR is reacted with at least one vinyl ether monomer VEM at 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.

[0044] The at least vinyl ether monomer VEM is 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.

[0045] The vinyl ether monomer VEM of the general formula CH=CH-O-R, where R is a linear alkyl group having 8 to 16 carbon atoms, preferably 10 to 14 carbon atoms, more preferably 12 carbon atoms, is preferred.

[0046] Preferably, the vinyl ether monomer VEM is selected from the group consisting of octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether (DDVE), tetradecyl vinyl ether, and hexadecyl vinyl ether, preferably selected from the group consisting of decyl vinyl ether, dodecyl vinyl ether (DDVE), and tetradecyl vinyl ether, more preferably selected from dodecyl vinyl ether (DDVE). These are available from suppliers such as BASF and Aldrich.

[0047] Surprisingly, it has been found that the reaction product with a vinyl ether monomer having an R with more than 16 carbon atoms does not significantly reduce the decrease in swelling properties under activation conditions after a longer storage time. This is evident from Table 1, for example, the comparison between E-1 and Ref.2, or the comparison between E-2 and Ref.4.

[0048] At least one carboxyl group (e.g., carboxylic acid group)-containing acrylonitrile / butadiene rubber ABR can also contain pendant carboxy groups or carboxyl groups.

[0049] The carboxyl group-containing acrylonitrile / butadiene rubber ABR preferably 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, and even more preferably 0.05 EPHR to 0.1 EPHR.

[0050] Regarding the carboxyl group-containing acrylonitrile / butadiene rubber ABR, its carboxyl groups are preferably obtained by a termonomer such as methacrylic acid. The carboxyl group-containing acrylonitrile / butadiene rubber ABR is preferably acrylonitrile / butadiene / methacrylic acid rubber.

[0051] Particularly preferred carboxyl group-containing acrylonitrile / butadiene rubber ABR is available from Nippon Zeon under the trade name Hycar and is currently available under the trade name NIPOL.

[0052] The carboxyl group-containing acrylonitrile / butadiene rubber ABR preferably contains 10 wt% to 50 wt% nitrile, more preferably 20 wt% to 40 wt% nitrile, and even more preferably 25 wt% to 35 wt% nitrile.

[0053] The carboxyl group-containing acrylonitrile / butadiene rubber ABR preferably has a Mooney viscosity (ML1+4 at 100 °C) of 20 to 60 MU (Mooney units). The Mooney viscosity means a measure of the viscosity of the rubber. It is defined as the shear torque that resists the rotation of a cylindrical metal disk (or rotor) embedded in the rubber within a cylindrical cavity. The dimensions of the shear disk viscometer, the test temperature, and the measurement procedure for the Mooney viscosity are preferably specified in ASTM D1646 standard.

[0054] The carboxyl group-containing acrylonitrile / butadiene rubber ABR used for the reaction product RP may preferably have a Mooney viscosity (ML1+4 at 100 °C) of 20 to 34 MU (Mooney units). This is advantageous with respect to a larger compression strength value. This can be seen, for example, in the comparison between E-1 and E-2 in Table 1.

[0055] The carboxyl group-containing acrylonitrile / butadiene rubber ABR used for the reaction product RP may also preferably have a Mooney viscosity (ML1+4 at 100 °C) of 35 to 60 MU (Mooney units). This is advantageous with respect to a larger expansion value. This can be seen, for example, in the comparison between E-1 and E-2 in Table 1.

[0056] The one-component thermosetting epoxy resin composition may further contain at least one toughening modifier D. The toughening modifier D may be solid or liquid. In particular, the toughening modifier D is selected from the group consisting of a terminal-blocked polyurethane polymer D1, a liquid rubber D2, and a core-shell polymer D3. Preferably, the additional toughening modifier D is selected from the group consisting of a terminal-blocked polyurethane polymer D1 and a liquid rubber D2. The aforementioned liquid rubber D2 is not the same as the carboxyl group-containing acrylonitrile / butadiene rubber ABR.

[0057] The proportion of the toughening modifier D is preferably 1 to 10% by weight, more preferably 2.5 to 7.5% by weight, based on the total weight of the epoxy resin composition. It may also be preferable that the epoxy resin composition contains less than 2, preferably less than 1, less than 0.5, less than 0.1 of the toughening modifier D, and most preferably does not contain the toughening modifier D.

[0058] In a preferred embodiment, the one-component thermosetting epoxy resin composition further comprises at least one filler F. In this case, mica, talc, kaolin, wollastonite, feldspar, diorite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated calcium carbonate or heavy calcium carbonate), dolomite, quartz, silica (fumed silica or precipitated silica), cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic beads, hollow glass beads, hollow organic beads, glass beads, glass fibers or carbon fibers, and coloring pigments are preferred. Calcium carbonate, calcium oxide, talc, glass fibers or carbon fibers, and fumed silica are more preferred, and fillers selected from the group consisting of talc, glass fibers or carbon fibers, and fumed silica are particularly preferred.

[0059] The total proportion of all fillers 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.

[0060] The one-component thermosetting epoxy resin composition can further comprise additional components, in particular, catalysts, thixotropic agents, plasticizers, solvents, dyes and pigments, corrosion inhibitors, surfactants, defoaming agents, and adhesion promoters.

[0061] The one-component thermosetting epoxy resin composition comprises at least one physical or chemical blowing agent BA.

[0062] A chemical blowing agent is an organic or inorganic substance that forms or releases a gaseous substance under the influence of temperature, humidity, electromagnetic radiation, or a chemical substance. Such substances are, in particular, azodicarbonamide, sulfohydrazide, hydrogen carbonate, or carbonate. For example, when the temperature, pressure, or volume changes, especially when the temperature rises, a compound in which the substance changes to a gaseous state and thereby forms a foam structure by volume expansion can be used as a physical blowing agent. Such physical blowing agents are, in particular, liquids that evaporate at high temperatures. Furthermore, a gas or a low-boiling liquid introduced in microencapsulated form into the composition can be used as a physical blowing agent. Both chemical blowing agents and physical blowing agents can form a foam structure in a polymer composition.

[0063] Preferred physical blowing agents are expandable microspheres consisting of a thermoplastic shell filled with a thermally expandable liquid or gas. Such microspheres are commercially available, for example, under the trade name Expancel® from Akzo Nobel, Netherlands.

[0064] 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.

[0065] The ratio of the blowing agent BA is advantageously 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.

[0066] The one-component thermosetting epoxy resin composition can 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.

[0067] The ratio of the processing aid is advantageously 1 to 8% by weight, preferably 2 to 5% by weight, based on the total weight of the composition.

[0068] The one-component thermosetting epoxy resin composition preferably has a melt flow index (MFI) of 0.5 to 15 g / 10 min, particularly 1 to 10 g / 10 min, preferably 1 to 5 g / 10 min, and most preferably 1 to 3 g / 10 min.

[0069] The MFI is determined preferably at 110 °C and 2.16 kg in accordance with ASTM D1238 with a melt time of preferably 120 seconds.

[0070] The one-component thermosetting epoxy resin composition is preferably an injection-moldable mixture, i.e., this mixture has a viscosity suitable for injection molding at the processing temperature. In particular, it is injection-moldable without foaming.

[0071] Particularly preferred thermosetting one-component epoxy resin compositions are: - At least one epoxy resin A having on average more than one epoxide group per molecule, in an amount of 30 to 90 wt%, 35 to 85 wt%, 40 to 75 wt%, more preferably 45 to 60 wt%, based on the total weight of the one-component thermosetting epoxy resin composition; - At least one latent curing agent for the epoxy resin, particularly dicyandiamide, in an amount of 0.1 to 15 wt%, more preferably 0.2 to 5 wt%, particularly 0.5 to 3 wt%, based on the total weight of the one-component thermosetting epoxy resin composition; - A blowing agent BA in an amount of 0.1 to 7.5 wt%, preferably 0.5 to 5 wt%, particularly 1 to 4 wt%, based on the total weight of the epoxy resin composition; - At least one reaction product RP of at least one carboxyl group-containing acrylonitrile / butadiene rubber ABR and 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 between 8 and 16 carbon atoms, preferably a linear alkyl group, in an amount of 5 to 40 wt%, preferably 10 to 30 wt%, more preferably 15 to 25 wt%, based on the total amount of epoxy resin A; - Based on the total weight of the epoxy resin composition, preferably 5 to 40% by weight, preferably 20 to 40% by weight of filler F, which is calcium carbonate, calcium oxide, talc, glass fiber, and fumed silica, more preferably filler F selected from the group consisting of talc, glass fiber, and fumed silica, is included.

[0072] A preferred one-component thermosetting epoxy resin composition may be further advantageous when it consists of the aforementioned components in an amount exceeding 80% by weight, preferably exceeding 90% by weight, particularly exceeding 95% by weight, particularly preferably exceeding 98% by weight, and most preferably exceeding 99% by weight based on the total weight of the epoxy resin composition.

[0073] The one-component thermosetting epoxy resin composition is preferably non-tacky at 23°C. As used herein, the term "non-tacky" means that when a thumb is pressed against the surface of the one-component thermosetting epoxy resin composition with a pressure of about 5 kg for 1 second at 23°C, the thumb does not stick to the surface of the composition layer or the one-component thermosetting epoxy resin composition cannot be lifted.

[0074] The composition according to the present invention can be obtained by mixing the components in any suitable mixing device, for example, in a dispersion kneader, planetary mixer, twin-screw mixer, continuous mixer, extruder, or twin-screw extruder.

[0075] After mixing, the resulting composition can be shaped into a desired shape by, for example, extrusion molding, blow molding, pelletization, injection molding, compression molding, stamping or punching, or any other suitable method.

[0076] The mixing of the components preferably includes an extrusion molding step, and the mixed and extrusion-molded composition is then granulated. The granulated composition is then preferably shaped into a desired shape by injection molding.

[0077] The foaming of the one-component thermosetting epoxy resin composition is preferably carried out independently of the curing of the epoxy resin composition, particularly in advance. As a result, the epoxy resin composition cures only when most of the foaming of the epoxy resin composition has occurred. In other cases, the epoxy resin composition cures before reaching the intended location by foaming. Therefore, it is preferable that the curing temperature of the epoxy resin composition is higher than the foaming temperature of the epoxy resin composition.

[0078] Preferably, compared with the expansion of the expandable epoxy resin composition immediately after the production of the composition, the expandable epoxy resin composition shows a decrease in expansion under activation conditions after 3 months of storage at 35°C as follows (measurement described in the experimental section): - Expansion for 30 minutes at 180°C: less than 25%, preferably less than 15%, more preferably less than 5%.

[0079] It is more preferable that the expandable epoxy resin composition exhibits the following adhesion properties and properties (preferably by the measurement described in the experimental section): - Baking at 180°C for 30 minutes on LSS, HDG: ≥1.5 MPa, preferably ≥1.75 MPa, more preferably ≥2 MPa; and / or, preferably - Compressive strength: ≥5 MPa, preferably ≥6 MPa, more preferably ≥6 MPa.

[0080] Another aspect of the present invention is, in particular, a reinforcing element comprising a one-component thermosetting epoxy resin composition for reinforcing the cavity of a structural component.

[0081] The one-component thermosetting epoxy resin composition is preferably applied or attached to the carrier part.

[0082] This carrier part can be made of any material. Preferred materials are plastics, in particular polyurethanes, polyamides, polyesters, and polyolefins, preferably heat-resistant polymers such as poly(phenylene ether), polysulfone, or polyethersulfone (which also foam particularly); metals, in particular aluminum and steel; or any combination of these materials.

[0083] Furthermore, the carrier part can have any structure and configuration. For example, it can be solid or hollow, or can have a lattice structure. The surface of the carrier part can typically be smooth, rough, or structured. The carrier part can also contribute to structural reinforcement in addition to its function as a carrier for the foaming material.

[0084] The reinforcing element can also consist entirely of a one-component thermosetting epoxy resin composition without having a carrier part.

[0085] The reinforcing element comprising the carrier part and the one-component thermosetting epoxy resin composition is preferably manufactured by injection molding.

[0086] If the carrier part is made 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 this first component has solidified, the cavity in the mold is enlarged, or adapted, or the molded part is placed into a new mold, and the second component, in this case the epoxy resin composition, is molded onto the first component together with a second injection unit. If the carrier part is made of a material that cannot be manufactured by an injection molding process, for example a metal, the carrier part is placed in a suitable tool and the epoxy resin composition is injection molded onto the carrier part.

[0087] Naturally, there is also the possibility of fixing the epoxy resin composition to the carrier part by any other fixing means or method.

[0088] For the reinforcing element described, it is further advantageous if the thermal foaming and curing of the epoxy resin composition can be carried out at a temperature of 120°C to 220°C, preferably 140°C to 200°C, preferably within a time range of 10 to 60 minutes at said temperature.

[0089] Furthermore, the present invention includes the use of the aforementioned reinforcing element for reinforcing cavities in structural parts. This type of structural part is preferably used in means of transport and conveyance, in particular in the body and / or frame of vehicles on water or land or aircraft. The present invention preferably includes the use of the reinforcing element according to the invention in automobiles (in particular A-pillars, B-pillars, C-pillars, or D-pillars), trucks, lorries, boats, ships, helicopters, and airplanes, most preferably in the body or frame of an automobile.

[0090] Accordingly, a further aspect of the present invention is a method for reinforcing a structural part, comprising: i) placing a reinforcing element in a cavity according to the above description; and ii) heating said reinforcing element to a temperature of 120°C to 220°C, preferably 140°C to 200°C, preferably for 10 to 60 minutes. The method relates to a method comprising the above steps.

[0091] Preferably, step i) is carried out before step ii).

[0092] The present invention will be further illustrated by examples in the following text, but the examples are in no way intended to limit the present invention.

Examples

[0093] The materials and test methods used for testing each property in the examples were as follows:

[0094]

Table 1

[0095] Preparation of Reaction Products (Ref-RP1, Ref-RP2, RP1, and RP2) 150 grams of ABR1, 150 grams of ABR2, 35.84 grams of DDVE, and 45 grams of ODVE were each mixed in a Brabender mixer at a speed of 35 rpm for 50 minutes at 50 °C in the presence of 0.15 grams of 2-ethylhexyl phosphate. After confirming the conversion by FTIR, 9.3 grams of molecular sieve (zeolite) was added. Ref-RP1: Reaction product of ABR1 and ODVE Ref-RP2: Reaction product of ABR2 and ODVE RP1: Reaction product of ABR1 and DDVE RP2: Reaction product of ABR2 and DDVE

[0096] Preparation of Compositions Based on the information in Table 1, reference compositions Ref.1 to Ref.4 and compositions E-1 and E-2 according to the present invention were produced. The units of the amounts in Table 1 are % by weight.

[0097] The raw materials used were mixed at 90 °C for 20 minutes using a Brabender mixer (C.W. Brabender Prep-mixer model RS7500). Next, the produced compositions were compressed into sheets with a thickness of 3 - 4 mm using a heated hydraulic press at 80 °C. Then, such sheets were cut into dimensions desirable for the evaluation test.

[0098] The following measurements were performed on the obtained test pieces:

[0099] Viscosity Measurement The viscosities of compositions Ref.1 to Ref.4, E-1, and E-2 were measured on an Anton Paar Modular Compact Rheometer. The settings were a temperature of 110 °C, a frequency of 20 rad / s, and a strain of 3%. The sample size was a diameter of 1 inch and a thickness of 3 - 5 mm.

[0100] Measurement of Foam Density / Volume Expansion (Expansion) As described above, immediately after production, the composition was compressed into sheets with a thickness of 3 - 4 mm. These sheets were cut into 3 mm × 12 mm plaques. For these plaques, ether quantification was performed immediately after production (initial) or after being placed in a humidity chamber set at 35°C / 50% humidity for 3 months (3 months at 35°C / 50% humidity).

[0101] The volume expansion of each sample was quantified by measuring the density before and after expansion. The density was measured in accordance with DIN EN ISO 1183 using the water immersion method (Archimedes' principle) in deionized water and a precision balance for mass measurement. Expansion was measured by subjecting the test pieces to oven baking at 180°C for 30 minutes.

[0102] The volume expansion of the composition was quantified immediately after production (initial) and later.

[0103] Before expansion, all compositions Ref.1 - Ref.4, E - 1 and E - 2 were non - sticky at 23°C according to the above - mentioned definition.

[0104] Adhesion (LSS) measurement The adhesion strength was measured based on SAE J1523. An HDG plate coated with oil (width 25 mm, length 100 mm, and thickness 1 mm) was used. A composition material with dimensions of 25 × 25 × 3 mm was placed in between. After clamping the test piece in place, the test piece was baked at 180°C for 30 minutes. A tensile testing machine (Zwick) was used at a speed of 10 mm / min.

[0105] Measurement of compressive strength of the expansion material To determine the compressive strength characteristics, an uncured material was placed into a cylindrical tube with an inner diameter of 30 ± 2 mm lined with release paper in accordance with ASTM D1621 and cured for 30 minutes after the material reached 180°C. After completion of this baking, the material was abraded with sandpaper until a test piece with a diameter of 30 mm × height of 60 mm remained. After a conditioning time of 24 hours at 23°C, the above - mentioned cylinder was placed between two compression plates and the test was started at a speed of 10 mm / min up to a strain of 30%. The compressive strength was recorded.

[0106]

Table 2

Claims

1. a) at least one epoxy resin A having more than one epoxide group on average per molecule; b) with at least one latent curing agent for epoxy resin; c) with at least one physical or chemical blowing agent BA; d) At least one reaction product RP of acrylonitrile / butadiene rubber ABR containing at least one carboxyl group with at least one vinyl ether monomer VEM having the general formula CH=CH-O-R (wherein R is a branched or linear alkyl group having between 8 and 16 carbon atoms, preferably a linear alkyl group), A one-component thermosetting epoxy resin composition containing [the specified ingredient].

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

3. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the epoxy resin A is a solid epoxy resin.

4. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the acrylonitrile / butadiene rubber ABR containing at least one carboxyl group has a carboxyl content of 0.005 equivalents / 100 rubber (EPHR) to 0.4 EPHR, more preferably 0.01 EPHR to 0.2 EPHR, and even more preferably 0.05 EPHR to 0.1 EPHR.

5. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the at least one carboxyl group-containing acrylonitrile / butadiene rubber ABR contains 20% to 40% by weight of nitrile, preferably 25% to 35% by weight of nitrile.

6. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the at least one vinyl ether monomer VEM is selected from the group consisting of octyl vinyl ether, nonyl vinyl ether, decyl vinyl ether, dodecyl vinyl ether (DDVE), tetradecyl vinyl ether, and hexadecyl vinyl ether, preferably selected from the group consisting of 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 claim 1 or 2, wherein the at least one reaction product RP of at least one carboxyl group-containing acrylonitrile / butadiene rubber ABR with at least one vinyl ether monomer VEM is preferably a reaction product RP obtained by reacting at least one carboxyl group-containing acrylonitrile / butadiene rubber ABR with 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 group-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, and more preferably 2.2:1 to 1.8:

1.

9. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the proportion of the at least one reaction product RP between the acrylonitrile / butadiene rubber ABR containing at least one carboxyl group and at least one vinyl ether monomer VEM having the general formula CH=CH-O-R (wherein R is a branched or linear alkyl group having between 8 and 16 carbon atoms, preferably a linear alkyl group) is 5 to 40% by weight, preferably 10 to 30% by weight, and more preferably 15 to 25% by weight, based on the total amount of epoxy resin A.

10. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the latent curing agent is selected from dicyandiamide, guanamine, guanidine, aminoguanidine and their derivatives, substituted ureas, imidazoles, and amine complexes, preferably dicyandiamide.

11. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the one-component thermosetting epoxy resin composition further comprises at least one filler F, which is selected from the group consisting of calcium carbonate, calcium oxide, talc, glass fiber, and fumed silica, more preferably talc, glass fiber, and fumed silica.

12. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the ratio of the foaming agent BA is 0.1 to 7.5% by weight, preferably 0.5 to 5% by weight, and particularly 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 claim 1 or 2, wherein the one-component thermosetting epoxy resin composition has a melt flow index (MFI) of 0.5 to 15 g / 10 min, particularly 1 to 10 g / 10 min, preferably 1 to 5 g / 10 min, and most preferably 1 to 3 g / 10 min, as measured in accordance with ASTM D1238 at 110°C and 2.16 kg.

14. The one-component thermosetting epoxy resin composition according to claim 1 or 2, wherein the one-component thermosetting epoxy resin composition is non-stick at 23°C.

15. A reinforcing element comprising the one-component thermosetting epoxy resin composition according to claim 1 or 2, for reinforcing particularly within the cavities of structural components, preferably within the bodies and / or frames of means of transport and conveyance.

16. A method for reinforcing structural components, comprising the following steps: i) Placing the reinforcing element according to claim 15 within the cavity of a structural component, preferably within the body and / or frame of a means of transport and conveyance; ii) Heat the reinforcing element to a temperature of 120°C to 220°C, preferably 140°C to 200°C, preferably for 10 to 60 minutes. Methods that include...

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