Specific polymeric material for a baffle and / or reinforcer element

Abstract

Disclosed is a use of a polymeric material PM selected from the group consisting of polybutylene terephthalate (PBT), polyketones (PK) and maleic anhydride grafted polypropylene (MAH-PP) comprised in a carrier element of a baffle and / or reinforcement element with a thermally curable composition TC, preferably an thermally curable composition TC that is thermally expandible, deposited on the carrier element, to reduce the sagging and / or improve the sealing properties of the thermally curable composition TC.

Description

[0001] SPECIFIC POLYMERIC MATERIAL FOR A BAFFLE AND / OR REINFORCER ELEMENT

[0002] Technical Field

[0003] The present invention relates to the use of a polymeric material comprised in a carrier element of a baffle and / or reinforcement element with a thermally curable composition deposited on the carrier element. Said baffle and / or reinforcement element is preferably used to seal, baffle, or reinforce a cavity or hollow structure of a land-, water-, or air-vehicle, preferably an automotive vehicle.

[0004] Background of the Invention

[0005] Manufactured products often contain orifices and cavities or other hollow parts that result from the manufacturing process and / or that are designed into the product for various purposes, such as weight reduction. Automotive vehicles, for example, include several such orifices and cavities throughout the vehicle, including in the vehicle's structural pillars and in the sheet metal of the vehicle doors. It is often desirable to seal such orifices and cavities so as to minimize noise, vibrations, fumes, dirt, water, humidity, and the like from passing from one area to another within the vehicle by means of sealing members or baffle elements built into the orifice or cavity. Likewise, such members or elements often fulfil an additional task of reinforcing the hollow structure of the manufactured product, e.g. automotive part, so much that it becomes more resistant to mechanical stress but still maintains the low weight advantage of the hollow structure.

[0006] Such elements used for sealing, baffling or reinforcing often consist of a carrier, made of plastic, metal, or another rigid material, and one or more layers of a thermoplastic material attached to it which is able to expand its volume when heat or another physical or chemical form of energy is applied, but they can also be entirely made of expandable material. Using an adequate design, it is possible to insert the baffle or reinforcement element into the hollow part of the structure during the manufacturing process but also to leave the inner walls of the structure still accessible (or the cavities passable) by e.g. a liquid. For example, during the manufacture process of a vehicle, the hollow parts of a metal frame can still be largely covered by an electrocoating liquid while the baffle or reinforcement elements are already inserted, and afterwards during a heat treatment step, the expandable thermoplastic material of the baffle or reinforcement element expands to fill the cavities as intended.

[0007] The development of such baffles or reinforcement elements has led to highly advanced systems, where the expandable material is able to increase its volume by up to 1500% or more, forming a foam-like structure that fills the cavities and adhering to the walls of the structure intended to be sealed, baffled, or reinforced. Especially in automotive manufacturing, this has led to considerable weight reduction and excellent dampening of noise or vibrations in the car body.

[0008] Currently employed thermally expandable compositions can consist of polymers that can be cross-linked by peroxides, such as ethylene-vinyl acetate polymers, in combination with comparably small, highly functional acrylates which are incorporated into the cross-linked network upon curing. These compositions furthermore contain blowing agents. Under activation conditions, such as elevated temperature, curing of the cross-linkable network takes place, while simultaneously the blowing agent decomposes and releases gases. This leads to the above- mentioned volume expansion and the formation of a stable foam which in ideal cases fills the cavity as intended and adheres to its walls. Such a system is for example disclosed in DE 10 2011 080 223 Al.

[0009] For baffle and / or reinforcement elements to perform well with respect to sealing, baffling, or reinforcing, it is important that the thermally curable composition remains at the intended position under activation condition and do not slip away from the original position on the carrier (so called "sagging"). In addition, once cured it is important that the composition shows sufficient sealing properties to avoid the transfer / passage of water through the sealed cavities.

[0010] It is thus desirable to obtain a baffle and / or reinforcement element that does not suffer from these limitations and leads to reduced sagging and / or improved sealing properties of the thermally curable composition. Prior art documents have disclosed various carrier materials and thermally curable compositions for sealing and reinforcement applications. US 2018 / 0057717 Al describes reinforcement members comprising heat-curable structural adhesives on carrier members made of fiber- reinforced polyester materials, including polybutylene terephthalate, for use in automotive applications. US 2015 / 0246646 Al discloses thermally expandable formulations containing peroxidically crosslinkable polymers and blowing agents for baffle parts, with focus on preventing runoff and slippage during curing processes. However, these prior art documents do not specifically address the problem of sagging of thermally curable compositions after prolonged exposure to elevated humidity conditions, nor do they disclose the specific selection of polymeric materials that provide reduced sagging and improved sealing properties under such conditions.

[0011] Summary of the Invention

[0012] It is an object of the present invention to provide a baffle and / or reinforcement element wherein the thermally curable composition shows reduced sagging and / or improved sealing properties.

[0013] Surprisingly, the present invention provides a solution to that problem by the use of polymeric material PM selected from the group consisting of polybutylene terephthalate (PBT), polyketones (PK) and maleic anhydride grafted polypropylene (MAH-PP), preferably polybutylene terephthalate and polyketones, most preferably polybutylene terephthalates, comprised in a carrier element of a baffle and / or reinforcement element with a thermally curable composition TC, preferably an thermally curable composition TC that is thermally expandible, deposited on the carrier element, to reduce the sagging and / or improve the sealing properties of the thermally curable composition TC.

[0014] The reducing of the sagging and / or the improving of the sealing properties of the thermally curable composition TC is compared to a baffle and / or reinforcement element with a carrier element that is not comprising the polymeric material PM, in particular compared to a baffle and / or reinforcement element with a carrier element that is comprising polyamide 66.

[0015] The reducing of the sagging and / or the improving of the sealing properties of the thermally curable composition TC is determined as described in the description below. It was surprisingly found that the inventive selection of the polymeric material PM as the carrier material leads to reduced sagging and / or improved sealing properties of the thermally curable composition after prolonged exposure of the carrier element to elevated relative humidity conditions prior to the activation and / or expansion of the thermally curable composition.

[0016] For the mentioned use, the baffle and / or reinforcement element is preferably used to seal, baffle, or reinforce a cavity or hollow structure of a land-, water-, or airvehicle, preferably an automotive vehicle. Further aspects of the present invention are subject of other independent claims. Preferred embodiments of the invention are subject of dependent claims. Detailed Description of the Invention

[0017] The unit term "wt.-%" means percentage by weight, based on the weight of the respective total composition, if not otherwise specified. The terms "weight" and "mass" are used interchangeably throughout this document.

[0018] The term "functionality" in connection with a molecule describes in this document the number of chemical functional groups per molecule. The term "polyfunctional" describes a molecule with more than 1 functional groups of a given type. For example, a polyfunctional acrylate with a functionality of 3 describes a molecule with 3 acrylate groups. The term "average functionality" is used if a mixture of molecules is present that differ slightly in individual functionality, but in average exhibit a given functionality, as it is sometimes the case with technical grade chemicals.

[0019] The term "equivalent" in connection with chemical functional groups describes in this document the mass amount of a substance that equals its equivalent weight. Normally, the equivalent weight is defined as the amount of substance that contains 1 mole of a defined functional group, such as an acrylate group or a peroxide function. The ordinarily skilled artisan in the field of polymer composition formulation uses such numbers to calculate appropriate ratios for active components, and such values are commonly provided by producers of functional chemicals, especially polymers. Accordingly, the "equivalent ratio" (EQ) of two substances is understood herein as the ratio of the equivalents of a first substance to the equivalents of the second substance in a given composition.

[0020] The term "radical" used in this document describes, as known to a person with ordinary skill in the art of chemistry, a chemical species with an unpaired valence electron. The cross-linking reactions involved in the curing or hardening of the polymer system follow a radical mechanism.

[0021] All industry standards and norms mentioned in the document refer to the versions valid at the date of first filing, unless stated otherwise.

[0022] Melt flow index (MFI) is determined by the ASTM D1238 standard method, using a capillary rheometer at 190 °C and a weight of 2.16 kg, except specifically indicated otherwise. MFI values describe the amount of polymer coming out of the capillary under pressure of the defined weight and at the defined temperature during a given time.

[0023] The thermally curable composition TC is preferably selected from the group consisting of thermosetting one-component epoxy resin compositions, one-component polyurethane compositions and materials containing at least one polymer P, cross- linkable by peroxide, preferably materials containing at least one polymer P, crosslinkable by peroxide.

[0024] It is further preferred, if the thermally curable composition TC has an MFI of 1 - 50 g / 10 min, determined by the ASTM D1238 standard method, using a capillary rheometer at 190 °C and a weight of 2.16 kg.

[0025] The thermally curable composition TC is preferably a thermally curable composition TC that is thermally expandible. Hence, the thermally curable composition TC preferably comprises at least one blowing agent BA.

[0026] A suitable blowing agent BA may be a chemical or physical blowing agent. Preferably, the at least one blowing agent BA is a chemical blowing agent.

[0027] The at least one physical or chemical blowing agent BA preferably has an activation temperature from 120 °C to 210 °C, preferably from 140 °C to 200 °C.

[0028] Suitable chemical blowing agents include, but are not limited to, azo compounds, hydrazides, nitroso compounds, carbamates, carbazides, bicarbonates, polycarboxylic acids, and salts of polycarboxylic acids.

[0029] According to one or more embodiments, the at least one blowing agent BA is selected from the group consisting of azodicarbonamide, azoisobutytronitrile, azocyclohexyl nitrile, dinitrosopentamethylene tetramine, azodiamino benzene, benzene-1,3- sulfonyl hydrazide, calcium azide, 4,4 ' -diphenyldisulphonyl azide, p-toluenesulphonyl hydrazide, p-toluenesulphonyl semicarbazide, 4,4'- oxybis(benzenesulphonylhydrazide), trihydrazino triazine, and N,N'-dimethyl-N,N'- dinitrosoterephthalamide, and combinations thereof, preferably azodicarbonamide or 4,4'-oxybis(benzenesulphonylhydrazide).

[0030] Suitable physical blowing agents further include expandable microspheres, consisting of a thermoplastic shell filled with thermally expandable fluids or gases. Suitable expandable microspheres are commercially available, for example, under the trademark of Expancel® microspheres (from AkzoNobel).

[0031] Preferably, the at least one blowing agent BA is present in an amount of 0.25 -15 wt.-%, based on the total weight of the thermally curable composition TC.

[0032] A thermally curable composition TC that is thermally expandible is preferably foamable at a temperature of <220°C, preferably <210°C, in particular of 80°C to 200°C, preferably of 140°C to 200°C. In particular, this is over a period of time of 10-60 min. In this way, said thermally curable composition TC that is thermally expandible can be foamed in already established process steps in vehicle manufacturing. In case the thermally curable composition TC is thermally expandible, it preferably has an expansion rate of 100% - 4000%, preferably 500% - 3000%, more preferably 1000% - 2500%. Preferably the expansion rate is determined by volume changes on the thermally expandable material using the DIN EN ISO 1183 method of density measurement (Archimedes principle) in deionised water in combination with sample mass determined by a precision balance.

[0033] In case the thermally curable composition TC is a one-component polyurethane composition, the one-component polyurethane composition is a heat-hardening polyurethane composition, which is built up from polymeric polyols and polyisocyanates. Suitable polyisocyanates are in particular di- and triisocyanates. Such a polyurethane composition contains at least one hardening agent, which contains groups that are reactive to isocyanates and is present in blocked form. In this case, the blocking can have a chemical or physical nature.

[0034] In case the thermally curable composition TC is a thermosetting one-component epoxy resin composition, this selection is especially preferred if the element according to the invention is a reinforcement element.

[0035] Preferably, the one-component thermosetting epoxy resin composition comprises:

[0036] - at least one epoxy resin A having on average more than one epoxide group per molecule, preferably a solid epoxy resin, the fraction of the epoxy resin A preferably being from 30 - 90 wt.-%, based on the total weight of the one- component thermosetting epoxy resin composition; and

[0037] - at least one latent hardener B for epoxy resins; and

[0038] - preferably at least one accelerator C for epoxy resins; and

[0039] - at least one toughness improver D, the fraction of toughness improver D preferably being from 1 - 10 wt.-%, based on the total weight of the one-component thermosetting epoxy resin composition, and;

[0040] - at least one blowing agent BA, preferably selected from azodicarbonamide and 4,4'-oxybis (benzenesulphonylhydrazide, preferably between 0.25 and 5 wt. -%, based on the total weight of the composition.

[0041] The thermosetting one-component epoxy resin composition comprises at least one epoxy resin A having on average more than one epoxide group per molecule. Preferably, the at least one epoxy resin A having on average more than one epoxide group per molecule is a solid epoxy resin. The term "solid epoxy resin" is very familiar to the person skilled in the epoxide art and is used in contrast to "liquid epoxy resins". The glass transition temperature of solid resins is above room temperature, meaning that at room temperature they can be comminuted into pourable powders. It is preferred if more than 70 wt. -%, more preferred more than 80 wt.-%, more than 90 wt.-%, more than 95 wt.-%, more than 98 wt.-%, of the epoxy resin A is a solid epoxy resin.

[0042] Preferred epoxy resins have the formula (I)

[0043] In this formula, the substituents R' and R" independently of one another are either H or CH3. In solid epoxy resins, the index s has a value of > 1.5, more particularly from 2 to 12.

[0044] Solid epoxy resins of this kind are available commercially, for example, from Dow or Huntsman or Hexion.

[0045] Compounds of the formula (I) having an index s of 1 to 1.5 are referred to by the person skilled in the art as semi-solid epoxy resins. For the purposes of the present invention, they are considered likewise to be solid resins. Preferred solid epoxy resins, however, are epoxy resins in the narrower sense, in other words where the index s has a value of > 1.5.

[0046] In the case of liquid epoxy resins, the index s has a value of less than 1. Preferably s has a value of less than 0.2.

[0047] The resins in question are therefore preferably diglycidyl ethers of bisphenol A (DGEBA), of bisphenol F and also of bisphenol A / F. Liquid resins of these kinds 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).

[0048] Of further suitability as epoxy resin A are what are called epoxy novolacs. These compounds have, in particular, the following formula: methyl and z = 0 to 7. More particularly these are phenol-epoxy or cresol-epoxy novolacs (R2 = CH2).

[0049] Epoxy resins of these kinds are available commercially under the tradename EPN or ECN and also Tactix® from Huntsman, or within the product series D.E.N.™ from Dow Chemical.

[0050] The epoxy resin A is preferably a solid epoxy resin of the formula (I).

[0051] The fraction of the epoxy resin A is preferably from 30 - 90 wt.-%, based on the total weight of the one-component thermosetting epoxy resin composition, preferably from 40 - 70 wt.- %, most preferably 50 - 60 wt.-%.

[0052] The thermosetting one-component epoxy resin composition further comprises at least one latent hardener B for epoxy resins. Latent hardeners are substantially inert at room temperature and are activated by elevated temperature, typically at temperatures of 70°C or more, thereby initiating the curing reaction. The customary latent hardeners for epoxy resins can be used. Preference is given to a latent epoxy resin hardener B containing nitrogen.

[0053] The latent hardener B is preferably selected from dicyandiamide, guanamines, guanidines, aminoguanidines and derivatives thereof, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide.

[0054] The latent hardener B is preferably used in a stoichiometric amount based on the epoxy groups in the composition. The molar ratio of the epoxy groups to the active hydrogen of the latent hardener B is preferably 0.8 to 1.2, in particular 0.9 to 1.1, preferably 0.95 to 1.05.

[0055] The fraction of the latent hardener B is preferably 0.5 to 12 wt%, more preferably 1 to 8 wt%, more particularly 2-6 wt%, based on the total weight of the epoxy resin composition.

[0056] The thermosetting one-component epoxy resin composition preferably further comprises at least one accelerator C for epoxy resins.

[0057] Such accelerating curing agents are preferably substituted ureas, for example 3-(3-chloro-4- methylphenyl)-l,l-dimethylurea (chlortoluron) or phenyldimethylureas, especially p- chlorophenyl-N, N -di methyl urea (monuron), 3-phenyl-l,l-dimethylurea (fenuron) or 3,4- dichlorophenyl-N,N-dimethylurea (diuron). In addition, it is possible to use compounds from the class of the imidazoles, such as 2-isopropylimidazole or 2-hydroxy-N-(2-(2-(2-hydroxy- phenyl)-4,5-dihydroimidazol-l-yl)ethyl)benzamide, imidazolines, trihalide complexes, preferably BF3complexes, blocked amines and encapsulated amines.

[0058] Preferably, the accelerator C for epoxy resins is selected from the list consisting of substituted ureas, imidazoles, imidazolines and blocked amines, preferably substituted ureas.

[0059] The one-component thermosetting epoxy resin composition comprises at least one toughness improver D. The toughness improvers D may be solid or liquid.

[0060] More particularly the toughness improver D is selected from the group consisting of terminally blocked polyurethane polymers DI, liquid rubbers D2 and core-shell polymers D3. With preference the additional toughness improver D is selected from the group consisting of terminally blocked polyurethane polymers DI and liquid rubbers D2, most preferably liquid rubbers D2.

[0061] Preferred liquid rubbers D2 are carboxyl group (e.g., carboxylic acid groups) containing acrylonitrile / butadiene rubber ABR and reaction products thereof with polyepoxides and / or polyphenols.

[0062] Such carboxyl group containing acrylonitrile / butadiene rubbers ABR may also include pendant carboxy or carboxyl groups.

[0063] The carboxyl group containing acrylonitrile / butadiene rubbers ABR preferably have a carboxyl content of 0.005 equivalents per hundred rubbers (EPHR) to 0.4 EPHR, more preferably from 0.01 EPHR to 0.2 EPHR and even more preferably from 0.05 EPHR to 0.1 EPHR.

[0064] For the carboxyl group containing acrylonitrile / butadiene rubbers ABR, the carboxylic groups are preferably provided by a termonomer such as methacrylic acid. The carboxyl groups containing acrylonitrile / butadiene rubbers ABR preferably are acrylonitrile / butadiene / methacrylic acid rubbers.

[0065] Particularly preferred carboxyl group containing acrylonitrile / butadiene rubbers ABR are available from Nippon Zeon under the trade name Hycar, now available under the trade name NIPOL.

[0066] The carboxyl group containing acrylonitrile / butadiene rubbers ABR preferably include from 10% - 50% by weight nitrile, more preferably 20% - 40% by weight nitrile and even more preferably 25% - 35% by weight nitrile.

[0067] More preferably, the liquid rubbers D2 are epoxy resin modified acrylonitrilebutadiene copolymers. For example, they can be produced by reacting carboxy- or epoxy-terminated acrylonitrile-butadiene copolymers, also known as liquid rubbers, with polyepoxides and / or polyphenols. Preferably, the at least one epoxy resin modified acrylonitrile-butadiene copolymer is obtained by reacting one or more carboxyl-terminated butadiene-acrylonitrile copolymers (CTBN) with one or more solid epoxy resins of the formula (I) and / or one or more liquid epoxy resin of the formula (I) and / or one or more novolac type epoxy resin.

[0068] Suitable epoxy resin modified acrylonitrile-butadiene copolymers are commercially available, for example, under the trade name of Struktol® from Schill & Seilacher Gruppe, Germany, such as Struktol® 3604, Struktol® 3606, Struktol® 3611, Struktol® 3614, Struktol® 3654, and Struktol® 3656. Suitable epoxy resin modified acrylonitrile-butadiene copolymers also include the mixtures of polymers disclosed in US patent 9,796,809 B2 as "impact strength improving agents for epoxy resin compositions".

[0069] The fraction of toughness improver D is preferably from 1 - 10 wt%, more preferably 2.5 -7.5 wt%, based on the total weight of the epoxy resin composition.

[0070] In one preferred embodiment, the one-component thermosetting epoxy resin composition further comprises at least one filler F. Preference here is given to mica, talc, kaolin, wollastonite, feldspar, syenite, chlorite, bentonite, montmorillonite, calcium carbonate (precipitated or ground), dolomite, quartz, silicas (fumed or precipitated), cristobalite, calcium oxide, aluminium hydroxide, magnesium oxide, 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, hollow glass beads and fumed silicas, more preferably talc, glass fibers, hollow glass beads, calcium carbonate and fumed silicas.

[0071] The total fraction of the overall filler F is advantageously 5-50 weight-%, preferably 15-45 weight-%, more preferably 20-40 weight-%, based on the total weight of the epoxy resin composition.

[0072] The one-component thermosetting epoxy resin composition may comprise further constituents, especially catalysts, thixotropic agents, plasticizers, solvents, dyes and pigments, corrosion inhibitors, defoamers and adhesion promoters.

[0073] The proportion of the blowing agent BA is advantageously 0.25-5% by weight, preferably 0.5-3% by weight, in particular 1-2% by weight, based on the total weight of the one-component thermosetting epoxy resin composition.

[0074] The thermally curable composition TC is preferably a material containing at least one polymer P, cross-linkable by peroxide. Such a thermally curable composition TC preferably comprises:

[0075] (a) at least one polymer P, cross-linkable by peroxide, and

[0076] (b) preferably at least one acrylate A, and

[0077] (c) at least one peroxide PE, and

[0078] (d) At least one blowing agent BA, preferably azodicarbonamide.

[0079] As the at least one polymer P that is cross-linkable by peroxide, principally all thermoplastic polymers or thermoplastic elastomers capable of cross-linking reactions with peroxides are suitable. The artisan skilled in the field describes polymers as "cross-linkable by peroxide" if these polymers contain functional groups, e.g. C-C double bonds, which release hydrogen atoms under influence of a radical starter, e.g. a peroxide, from their backbone or side chain, such that a radical remains that is able to radically attack other polymer chains in a subsequent step, leading to a radical chain reaction cross-linking process and ultimately to a polymer network.

[0080] Suitable polymers P include, for example, styrene-butadiene copolymers, styreneisoprene copolymers, ethylene-vinyl acetate copolymers, ethylene-methacrylate copolymers, ethylene-ethyl acrylate copolymers, ethylene butyl acrylate copolymers, ethylene-(meth) acrylic acid copolymers, ethylene-2-ethylhexyl acrylate copolymers, ethylene-acrylic ester copolymers, polyolefine block copolymers, and polyolefins such as polyethylene or polypropylene.

[0081] The copolymers, meaning polymers made from more than one type of monomer, can be block type copolymers or random copolymers.

[0082] Polymers P can also be further functionalised, meaning they can contain further functional groups such as hydroxyl, carboxy, anhydride, acrylate, and / or glycidylmethacrylate groups.

[0083] Preferred is one or more polymer P with an average melt flow index (MFI) of between 1 and 200 g / 10 min, preferably between 10 and 100 g / 10 min, more preferably between 25 and 75 g / 10 min, most preferably between 35 and 55 g / 10 min.

[0084] The polymer P preferably comprises ethylene-vinyl acetate (EVA). More preferably more than 70 wt-%, more than 80 wt-%, more than 90 wt-%, more than 95 wt-%, more than 99 wt-%, of the Polymer P consists of ethylene-vinyl acetate (EVA), based on the total amount of the Polymer P.

[0085] In this case, the content of vinyl acetate monomers in EVA should be between 8 and 45 wt.-%, preferably between 15 and 30 wt.-%, based on the total weight of the EVA polymer.

[0086] In cases where more than one type of polymer is used, the individual MFI combine to an average MFI of the used polymer mixture, which has to be determined according to ASTM D1238.

[0087] The thermally curable composition preferably contains said at least one polymer P with an amount of between 30 and 80 wt.-%, preferably between 40 and 70 wt.-%, more preferably between 40 and 60 wt.-%, based on the weight of the total composition.

[0088] In a preferred embodiment, more than one type of polymer is used as polymer P. It was found to be beneficial for the properties of the composition to use at least two types of polymers (herein named Pl and P2) with different melt flow index (MFI), one much higher than the other. For example, an especially preferred embodiment uses a first polymer Pl with an MFI of between 100 and 200 g / 10 min and a second polymer P2 with an MFI of between 0.1 and 60 g / 10 min, preferably between 0.1 and 10 g / 10 min, preferably with a weight ratio of the two polymers Pl : P2 in the composition of 0.7 to 1.3, preferably 0.8 to 1.2.

[0089] Preferred EVA polymers include, e.g., Elvax® 150, Elvax® 240A, Elvax® 260A, Elvax® 420A (all by DuPont), or the corresponding Evatane® copolymers (by Arkema).

[0090] A second component of a preferred thermally curable composition is at least one acrylate A.

[0091] Preferably, the acrylate A is present with an amount of between 0.1 and 5 wt.-%, preferably between 0.2 and 2 wt.-%, more preferably between 0.3 and 0.75 wt.-%, based on the total weight of the composition.

[0092] Acrylate A preferably has a molecular weight of less than 2'500 g / mol, more preferably less than 1'000 g / mol.

[0093] Acrylate A preferably exhibits an acrylate functionality of at least 2 or 3, preferably between 2 and 6, more preferably between 3 and 5, most preferably 5. More preferably, the acrylate A comprises a polyfunctional acrylate with an acrylate functionality of at least 2 or 3, preferably between 2 and 6, more preferably between 3 and 5, most preferably 5, in an amount of more than 70 wt-%, more than 80 wt- %, more than 90 wt-%, more than 95 wt-%, more than 99 wt-%, based on the total amount of the Acrylate A.

[0094] Although polymer P (described above) can comprise acrylate functions, it is beneficial for the composition that these two components are not the same chemical compound. In comparison, acrylate A is generally smaller than polymer P in terms of molecular weight and acts as cross-linker for polymer P also. Only using one of the two components would either lead to poor mechanical properties in the final product or would inhibit the formation of a stable foam structure during and after expansion.

[0095] Preferred acrylates A with a functionality of 2 include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, tripropylene glycol dimethacrylate, 1,3-butanediol dimethacrylate, 1,4- butanediol dimethacrylate, 1,10-dodecanediol dimethacrylate, 1,6-hexandieol dimethacrylate, neopentylglycol dimethacrylate, and polybutylene glycol dimethacrylate.

[0096] Preferred acrylates A with a functionality of 3 or higher include glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetraacrylate, Di-(tri methylolpropane) tetraacrylate, pentraerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tri(2 -methacryloxyethyl) trimellitate, tri(2-acryloxyethyl) isocyanurate, as well as their ethoxylated or propoxylated derivates.

[0097] Especially preferred acrylates A exhibit a functionality of 5, such as dipentaerythritol pentaacrylate.

[0098] Further preferred acrylates include highly functional, hyperbranched acrylates with functionalities of between 6 and 16, or higher. Examples of such preferred acrylates include hyperbranched polyester-polyacrylates, for example Sartomer® CN2303 and Sartomer® CN2305, both by Arkema.

[0099] A third component of the preferred thermally curable composition is at least one peroxide PE.

[0100] The thermally curable composition preferably contains said peroxide PE in an amount of between 2.5 and 5 wt.-%, preferably between 2.8 and 4.8 wt.-%, based on the total weight of the composition.

[0101] Preferred peroxides are organic peroxides, such as keton peroxides, diacyl peroxides, peresters, perketals, and hydroperoxides. Examples of such preferred peroxides include cumene hydroperoxide, t-butyl peroxide, bis(t-butylperoxy)-diisopropyl benzene, di(t-butylperoxy isopropyl) benzene, dicumyl peroxide, t-butylperoxy benzoate, di -alkyl peroxy dicarbonate, diperoxyketals (such as 1,1-di-t-butylperoxy- 3,3,5-trimethyl cyclohexane), keton peroxides (such as methyl ethyl keton peroxide), and 4,4-di-t-butylperoxy-n-butyl valerate.

[0102] Especially preferred are 3,3,5,7,7-pentamethyl-l,2,4-trioxepane, 2,5-dimethyl-2,5- di(t-butylperoxy)-3-hexyne, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy) hexane, t-butyl cumyl peroxide, di(t-butylperoxy isopropyl) benzene, dicumyl peroxide, butyl-4,4-di(t-butylperoxy) valerate, t-butyl peroxy-2-ethyl hexyl carbonate, l,l-di(t-butylperoxy)-3,3,5-trimethyl cyclohexane, t-butylperoxy benzoate, di(4- methylbenzoyl) peroxide, and dibenzoyl peroxide.

[0103] Most preferred peroxides include dicumyl peroxide, available for example under the trade names Perkadox® BC-40B-PD by Akzo Nobel or Peroxan® DC-40 PK by Pergan and / or di(t-butylperoxyisopropyl) benzene, available for example under the trade names Perkadox® 14-40B-PD by Akzo Nobel or Peroxan® BIB-40 P by Pergan, wherein di(t-butylperoxyisopropyl) benzene is especially preferred.

[0104] It may be advantageous to use peroxide that is immobilized on a support material, such as silica, kaolin, and / or calcium carbonate, or other suitable materials. This approach may facilitate handling, dosage, and evenly distribution of the peroxide in the composition. Examples for such immobilized peroxide include Perkadox® BC-40B- PD by Akzo Nobel (40 wt.-% dicumyl peroxide on calcium carbonate) or Perkadox® 14-40K-PD by Akzo Nobel (40 wt.-% di(t-butylperoxyisopropyl) benzene on clay and silica). However, care has to be taken in such cases to correctly calculate the wt. -% and especially the equivalents of active substance in the composition, as in this document these values always refer to active compound, and do not include possibly present support material.

[0105] A fourth component of a preferred thermally curable composition is at least one blowing agent BA, preferably azodicarbonamide. According to one or more embodiments, the at least one blowing agent BA comprises 0.1 - 5 wt.-%, preferably 0.25 - 3.5 wt.-%, more preferably 0.5 - 3 wt.-%, even more preferably 1 - 3 wt.-% of the total weight of the thermally curable composition. Apart from the above-mentioned ingredients, said preferred thermally curable composition may contain other components commonly used in such compositions and known to the ordinarily skilled artisan in the field. These include, for example, fillers, colorants, dispersion aids or homogenizers, adhesion promoters, antioxidants, stabilizers, and the like.

[0106] Suitable as fillers are, e.g., ground or precipitated calcium carbonate, calcium - magnesium carbonate, talcum, gypsum, graphite, barite, silica, silicates, mica, wollastonite, carbon black, or the mixtures thereof, or the like.

[0107] Fillers are, if at all, preferably incorporated in the compositions with an amount of between 1 and 15 wt.-%, based on the total weight of the composition.

[0108] Dispersion aids or homogenizers, sometimes described as wetting agents or surfaceactive agents, may be beneficial for the composition in order to facilitate a homogeneously mixed composition. Preferably used such compounds include hydrocarbon resins, for example Novares® TL 90 available from Rutgers, Germany, Wingtack® resins (by Cray Valley), Escorez® tackifying resins (e.g., Escorez® 1304, by ExxonMobil), and Piccotac® hydrocarbon resins (e.g., Piccotac® 1100 or Piccotac® 1100E, by Eastman). Such compounds are preferably included in the compositions with an amount of between 2 and 10 wt.-%, preferably between 4 and 8 wt.-%, more preferably between 5 and 7 wt.-%, based on the total weight of the composition.

[0109] In preferred embodiments, said preferred thermally curable composition may also include adhesion promoters. Preferably these substances are incorporated into the polymer network during the cross-linking reactions via functional groups similar to those present in polymer P. Suitable adhesion promoters include, for example, ethylene-glycidyl methacrylate copolymers, such as Lotader® ADX 1200S, Lotader® AX8840, Lotader® 3210, Lotader® 3410 (by Arkema) or Lotryl® copolymers (by Arkema).

[0110] Adhesion promoters are preferably used in compositions with an amount of between 2 and 15 wt.-%, preferably between 4 and 10 wt.-%, more preferably between 5 and 7 wt.-%, based on the total weight of the composition.

[0111] Said preferred thermally curable composition may can be manufactured by mixing the components in any suitable mixing apparatus, e.g. in a dispersion mixer, planetary mixer, twin mixer, continuous mixer, extruder, or dual screw extruder.

[0112] It may be advantageous to heat the components before or during mixing, either by applying external heat sources or by friction generated by the mixing process itself, in order to facilitate processing of the components into a homogeneous mixture by decreasing viscosities and / or melting of individual components. However, care has to be taken, e.g. by temperature monitoring and use of cooling devices where appropriate, not to exceed the activation temperatures of the azodicarbonamide and / or peroxide. The final composition is preferably essentially solid at room temperature (23 °C), meaning that it does not visibly deform at this temperature just by means of gravity during at least 24 h.

[0113] After mixing, the resulting composition may be shaped into its desired form by, e.g., extruding, blow-moulding, pelleting, injection moulding, compression moulding, punching or stamping or any other suitable process.

[0114] The thermally curable composition TC is deposited on the carrier element of a baffle and / or reinforcement element. Such elements are preferably used to seal, baffle, and / or reinforce hollow structures, e.g. a cavity in a hollow structural part of an automobile. Hollow parts in cars may include body components (e.g., panels), frame components (e.g., hydroformed tubes), pillar structures (e.g., A, B, C, or D-pillars), bumpers, roofs, or the like.

[0115] With regard to activation of the thermally curable composition TC when used in automotive manufacturing, it is advantageous to couple the thermal activation of the composition with another process step involving heat treatment. An example for such a process step is electrocoating (cathodic dip painting / coating) of the chassis or car body.

[0116] The thermally curable composition TC is deposited on the carrier element of a baffle and / or reinforcement element, preferably in direct contact with the carrier element. In the use according to the invention, the polymeric material PM is selected from the group consisting of polybutylene terephthalate (PBT), polyketones (PK) and maleic anhydride grafted polypropylene (MAH-PP), preferably polybutylene terephthalate and polyketones, most preferably polybutylene terephthalate (PBT).

[0117] It is further preferred if the polymeric material PM has a flexural strength value of 5 - 70, preferably 20 - 60 MPa (ASTM D790).

[0118] It is further preferred if the polymeric material PM has an MFI of 10 - 80 g / 10 min, determined by the ASTM D1238 standard method, using a capillary rheometer at 240 °C and a weight of 2.16 kg.

[0119] It was surprisingly found that said polymeric materials show a significant reduction in sagging after humidity exposure compared to polyamide 66 or polypropylene. This can be seen, for example, in table 3. Also, the difference between the sagging behavior without deliberate humidity exposure and with humidity exposure is significantly lower for the polymeric material PM compared to polyamide 66 or polypropylene.

[0120] It was further surprisingly found that said polymeric materials show intact sealing properties after humidity exposure compared to polyamide 66. This can be seen, for example, in table 3.

[0121] Preferably, the polymeric material PM is comprised in the carrier element in an amount of 25 - 100 wt.-%, preferably 50 - 100 wt.-%, more preferably 60 - 100 wt.- %, most preferably 70 - 100 wt.-%, based on the total weight of the carrier element.

[0122] The combination of reduced sagging and improved sealing properties achieved by the polymeric materials PM provides a synergistic technical effect that may be particularly advantageous in demanding applications. In some aspects, the simultaneous improvement of both properties may result in enhanced overall performance that exceeds what would be expected from addressing either property individually.

[0123] The reduced sagging behavior may contribute to maintaining the intended positioning of the thermally curable composition TC during thermal activation, which in turn may support the achievement of optimal sealing performance. When the thermally curable composition TC remains in its designed location rather than flowing away from the intended sealing areas, the resulting foam structure may more effectively fill the target cavities and establish proper contact with the surrounding surfaces. In some cases, the improved sealing properties may work in conjunction with the reduced sagging to provide more reliable long-term performance. The maintained dimensional stability of the carrier element under varying humidity conditions may help preserve the integrity of the seal interface, while the enhanced sealing capability may ensure continued protection against the passage of water, air, or other substances through the sealed structure.

[0124] This combined effect may be particularly beneficial in automotive applications where baffle and / or reinforcement elements are exposed to varying environmental conditions during manufacturing processes such as electrocoating, as well as during the service life of the vehicle. The dual improvement may contribute to more consistent manufacturing outcomes and enhanced durability of the sealing function over time.

[0125] In some embodiments, the synergistic effect of reduced sagging and improved sealing properties may also contribute to broader manufacturing tolerances and increased process robustness, potentially reducing the need for precise environmental control during production and storage of the baffle and / or reinforcement elements prior to their thermal activation.

[0126] It is further preferred that the carrier element further comprises fibers, preferably selected from glass fibers, carbon fibers and aramid fibers, preferably 5 - 50 wt.-% fibers, more preferably 20 - 40 wt.-% fibers, based on the total weight of the carrier element.

[0127] In case the carrier element further comprises fibers, it is preferred that the amount of other components besides the polymeric material PM and the fibers is less than 30 wt.-%, preferably less than 10 wt. -%, more preferably less than 5 wt. -%, most preferably less than 1 wt. -%, based on the total weight of the carrier element.

[0128] The carrier element can further exhibit any shape or geometry. It can also consist of several, not directly connected parts. For example, it can be massive, hollow, or foamed, or it can exhibit a grid-like structure. The surface of the carrier element can typically be smooth, rough, or structured, according to the intended use of the baffle and / or reinforcement element.

[0129] In the manufacturing process of a baffle and / or reinforcement element, if the material of the carrier element can be (injection-) moulded or extruded, the whole baffle and / or reinforcement element can be produced in a two-step injection-moulding process or a co-extrusion process of the carrier element and the thermally curable composition TC. If using a two-step injection moulding process, in a first step, material for the carrier element is injected into the mould. After solidification, the cavity of the injection moulding tool is enlarged or adjusted, or the injection -moulded piece is transferred into another tool and the second component, in this case the material for the thermally curable composition TC, is injected.

[0130] In a preferred use of the present invention, the baffle and / or reinforcement element as described above are used to seal, baffle, or reinforce a cavity or hollow structure of a land-, water-, or air-vehicle, preferably an automotive vehicle, and / or a cavity of a building such that the transmission of noise, vibrations, humidity, and / or heat is reduced, and / or the object surrounding said cavity is mechanically strengthened.

[0131] In a further preferred use, a baffle and / or reinforcement element as described above is introduced into said cavity or hollow structure and subsequently thermally cured and preferably thermally expanded such that said cavity or hollow structure is at least partially filled by the cured and preferably expanded composition. Preferred temperature for the thermal curing and preferably expansion process is between 80 °C and 200 °C, preferably over a period of time of 10-60 min.

[0132] In one preferred aspect, the reduction of the sagging using a carrier element according to the invention is characterized by a smaller ratio between the sagging in mm using the moist (3 days long exposure to 40°C at 100% relative humidity) carrier element and the sagging in mm using the dried (140°C for 3 hours at 50% relative humidity) carrier element; compared to said ratio obtained by a carrier element not comprising the polymeric material PM, in particular compared to a baffle and / or reinforcement element with a carrier element that is comprising polyamide 66.

[0133] Preferably, the carrier elements according to the invention have such a before mentioned ratio that is less than 75 %, preferably less than 60 %, more preferably less than 50 %, most preferably less than 30 %, of the ratio of a carrier element not comprising the polymeric material PM, in particular compared to a baffle and / or reinforcement element with a carrier element that is comprising polyamide 66. For example, the example "PK1" has a sagging value of 7 mm in case of the moist carrier element and a value of 6 mm in case of the dried carrier element. Hence the ratio is 1.166. In case of the non-inventive example "PAI", the sagging value is 15 mm in case of the moist carrier element and the value is 4 mm in case of the dried carrier element. In this case the ratio is 3.75. The example "PK1" has a ratio that is only 31 % of the ratio of the non-inventive example "PAI" and therefore significantly smaller. The invention is further explained in the following experimental part which, however, shall not be construed as limiting the scope of the invention. The present invention provides unexpected and surprising technical advantages that were not predictable from the prior art. The specific selection of polymeric materials PM from the group consisting of polybutylene terephthalate (PBT), polyketones (PK) and maleic anhydride grafted polypropylene (MAH-PP) demonstrates remarkable performance improvements that distinguish the invention from conventional carrier materials.

[0134] Unexpectedly, it was found that the inventive polymeric materials PM exhibit significantly reduced sagging behavior compared to conventional materials such as polyamide or polypropylene, particularly after prolonged exposure to elevated humidity conditions. This technical effect was not anticipated based on the known properties of these materials in other applications.

[0135] The experimental data presented in Table 3 demonstrates the surprising extent of these improvements. For example, when comparing the polyketone material PK1 with the conventional polyamide material PAI, the sagging performance shows dramatic differences. The PK1 material exhibits a sagging value of only 7 mm under moist conditions (after 3 days exposure to 40°C at 100% relative humidity) compared to 6 mm under dried conditions (140°C for 3 hours at 50% relative humidity), resulting in a moist-to-dry sagging ratio of approximately 1.17. In stark contrast, the conventional PAI material shows a sagging value of 15 mm under moist conditions compared to only 4 mm under dried conditions, resulting in a much higher moist-to-dry sagging ratio of 3.75.

[0136] This represents a reduction in the humidity-sensitivity ratio of approximately 69% (from 3.75 to 1.17), which was entirely unexpected. The PK1 material demonstrates a ratio that is only 31% of the ratio exhibited by the conventional PAI material, indicating a substantial improvement in dimensional stability under varying humidity conditions.

[0137] Similarly, the polybutylene terephthalate (PBT) material shows exceptional performance with sagging values of only 2 mm in both dried and moist conditions, demonstrating virtually no sensitivity to humidity exposure. This represents an even more dramatic improvement over conventional materials and was completely unpredictable from the prior art.

[0138] Furthermore, the inventive polymeric materials PM demonstrate superior sealing properties after humidity exposure. The experimental results show that while conventional polyamide materials (PAI) fail to maintain adequate sealing properties after humidity exposure (showing "No" sealing in the water sealing test), the inventive materials such as PBT and polyketones maintain intact sealing capabilities (showing "Yes" sealing in the water sealing test). This technical effect ensures reliable long-term performance of the baffle and / or reinforcement elements even when exposed to challenging environmental conditions during manufacturing or storage.

[0139] The combination of reduced sagging and maintained sealing properties represents a synergistic technical effect that was not achievable with prior art materials. This dual improvement is particularly valuable in automotive manufacturing applications where baffle and / or reinforcement elements may be exposed to varying humidity conditions during the manufacturing process, including during electrocoating and subsequent heat treatment steps.

[0140] The technical mechanism underlying these unexpected results may be related to the specific molecular structure and hygroscopic properties of the selected polymeric materials PM. Unlike conventional polyamide materials, which are known to absorb moisture and undergo dimensional changes, the selected materials appear to maintain their structural integrity and dimensional stability even under high humidity conditions. However, the extent of the improvement and the specific performance characteristics were not predictable from the known properties of these materials.

[0141] These unexpected results provide significant technical advantages in practical applications, including improved reliability of sealing performance, reduced manufacturing tolerances, enhanced process robustness, and extended service life of the baffle and / or reinforcement elements. The invention thus provides a non-obvious solution to the technical problem of humidity-induced performance degradation in thermally curable baffle systems.

[0142] Examples

[0143] 1. Formulation of example compositions

[0144] 1.1 Compositions

[0145] The thermally curable composition was prepared according to the procedure shown below. The exact individual composition in wt.-%, based on the total weight of the individual respective composition and details on the ingredients used therein, are listed in Table 1.

[0146] Table 1: Details on the ingredients and their trade names used in the thermally curable composition. 1.2 Mixing and moulding procedure

[0147] The thermally curable composition was prepared according to the following procedure:

[0148] In a first step, polymer Pl and polymer P2, the adhesion promoter, and the dispersion aid were mixed and melted at 95 °C with a mixing rate of 50 rpm (rounds per minute) during 10 min (minutes). After this, half of the activator amount was added during 1 min and mixing was continued during 4 min at 50 rpm. Mixing was continued at 20 rpm during 5 min until the mixture cooled down to 95 °C.

[0149] After this, the azodicarbonamide, acrylate, and the second half of the activator amount were added during 1 min, followed by mixing at 50 rpm for 1 min.

[0150] Finally, the peroxide and all the rest were added during 1 min and mixing was continued for 2 min at 50 rpm to obtain the thermally curable composition.

[0151] 1.3 Polymeric materials used as carrier materials

[0152] The polymeric materials used as carrier materials in the testing are listed in Table 2.

[0153] Table 2: Details on the polymeric materials used and their trade names.

[0154] 2 Testing of polymeric materials as carrier materials

[0155] 2.1 Sagging test

[0156] The foamable (thermally curable composition) was moulded into test shapes with a dimension of 25 x 25 x 4 mm. These test shapes were cooled down to room temperature (23 °C) and used for the subsequently described sagging test. A hole with a 3 mm radius was drilled into the center of the square shaped samples (25 x 25 x 4 mm) and in a plate of the polymeric material shown in table 2 to connect them using a 3 mm diameter pushpin. The plate of the polymeric material was either in the dry or in the moist state.

[0157] The drying of the polymeric material plates was done at 140°C for 3 hours at 50% relative humidity. Moist polymeric material plates were obtained through 3 days long exposure to 40°C at 100% relative humidity. The samples made of the square shaped samples pined to the polymeric material plates were placed into vertical position with the pin positioned in a horizontal position and stored at 120°C for 20 min to assess the amount of sagging. After this period of time, the samples were cooled down to 23 °C. Finaly, the difference in the direction of the center of gravity of the lowest position of the foamable sample before and after the heating process test was measured in mm, which represents the sagging value.

[0158] 2.2 U-shape water sealing test

[0159] A plate of the polymeric material shown in table 2 was used (100*150*4mm). The plate of the polymeric material was either in the dried or in the moist state. The drying of the polymeric material plates was done at 140°C for 3 hours at 50% relative humidity. Moist polymeric material plates were obtained through 1 day long exposure to 40°C at 100% relative humidity. The curable expandable composition of table 1 cut in a U shape (left and right side 60mm length and bottom side with 110mm length with a thickness of 4 mm) was placed on said plates of the polymeric material. The assembly was covered / sandwiched with a metal plate of the same size (100*150*4mm) as the plate of the polymeric material using 8 mm spacers to allow expansion of the thermally curable composition and thereby contacting the metal plate. The specimen was baked at 170°C for 30 minutes. After that it was cooled to room temperature, it was positioned vertically so that the U-shape of the foam material forms a receptacle that was filled to 2 / 3rdof its volume with a red coloured water. 24 hours later sealing of the specimen was evaluated. The result was assessed in the following way: Sealing "No" means = water was lost from the U-shaped receptacle made of foamed material after 24h.

[0160] Sealing "Yes" means = no water was lost from the U-shaped receptacle made of foamed material after 24h. Table 3: n.d. = not determined, PP-plate melts at 170°C.

Claims

CLAIMS1. Use of polymeric material PM selected from the group consisting of polybutylene terephthalate (PBT), polyketones (PK) and maleic anhydride grafted polypropylene (MAH-PP), preferably polybutylene terephthalate and polyketones, most preferably polybutylene terephthalate, comprised in a carrier element of a baffle and / or reinforcement element with a thermally curable composition TC, preferably a thermally curable composition TC that is thermally expandible, deposited on the carrier element, to reduce the sagging and / or improve the sealing properties of the thermally curable composition TC, wherein reducing the sagging and / or improving the sealing properties of the thermally curable composition TC is compared to a baffle and / or reinforcement element with a carrier element not comprising the polymeric material PM, in particular compared to a baffle and / or reinforcement element with a carrier element that is comprising polyamide 66; wherein the reducing of sagging and / or improving the sealing properties of the thermally curable composition TC is determined as described in the description.

2. The use according to claim 1, wherein the polymeric material PM is comprised in the carrier element in an amount of 50 - 100 wt.-%, preferably 60 - 100 wt.- %, based on the total weight of the carrier element.

3. The use according any of the preceding claims, wherein the polymeric material PM is polybutylene terephthalates.

4. The use according any of the preceding claims, wherein the carrier element comprises fibers, preferably selected from glass fibers, carbon fibers and aramid fibers, preferably 5 - 50 wt.-% fibers, more preferably 20 - 40 wt.-% fibers, based on the total weight of the carrier element.

5. The use according to any of the preceding claims, wherein the thermally curable composition TC contains at least one blowing agent BA.

6. The use according to any of the preceding claims, wherein the thermally curable composition TC is selected from the group consisting of thermosetting one-component epoxy resin compositions, one-component polyurethane compositions and materials containing at least one polymer P, cross-linkable by peroxide; preferably thermosetting one-component epoxy resin compositions and materials containing at least one polymer P, cross-linkable by peroxide; most preferably materials containing at least one polymer P, cross-linkable by peroxide.

7. The use according to claim 6, wherein the thermally curable composition TC comprises(a) at least one polymer P, cross-linkable by peroxide, and(b) preferably at least one acrylate A, and(c) at least one peroxide PE, and(d) At least one blowing agent BA, preferably azodicarbonamide.

8. The use according to any of the preceding claims, wherein the thermally curable composition TC has an MFI of 1 - 50 g / 10 min, determined by the ASTM D1238 standard method, using a capillary rheometer at 190 °C and a weight of 2.16 kg.

9. The use according to any of the preceding claims, wherein the thermally curable composition TC is thermally expandible, preferably with an expansion rate of 100% - 4000%, preferably 500% - 3000%, more preferably 1000% - 2500%, determined as described in the description.

10. The use according to any of the preceding claims, wherein the baffle and / or reinforcement element is used to seal, baffle, or reinforce a cavity or hollow structure of a land-, water-, or air-vehicle, preferably an automotive vehicle, such that the transmission of noise, vibrations, humidity, and / or heat is reduced, and / or the object surrounding said cavity is mechanically strengthened.

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