Thermaly conductive carrier for baffle or reinforcement element

Abstract

Disclosed is a baffle and / or reinforcement element comprising a thermally expandable composition TEC and a carrier element, wherein the carrier element consists of a plastic material MA with a thermal conductivity of more than 0.6 W / (mK), determined according to ASTM D5470. Said baffle and / or reinforcement element allows for an improved expansion of the thermally expandable composition upon exposure to reduced temperatures for limited time, preferably 10 – 15 min at 140 - 150 °C.

Description

[0001] THERMALY CONDUCTIVE CARRIER FOR BAFFLE OR REINFORCEMENT ELEMENT

[0002] Technical Field

[0003] The present invention relates to a baffle and / or reinforcement element for hollow structures comprising a thermally expandable composition and a process for manufacturing such a baffle and / or reinforcement element.

[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. 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 electro-coating 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 contain blowing agents. Under activation conditions, such as elevated temperature, curing of the crosslinkable 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] It is a current trend in the automotive industry to lower the temperature and time needed for the thermally expandable compositions to expand. It is thus desirable to obtain a baffle or reinforcement element containing a thermally expandable composition that allows for an improved expansion of the thermally expandable composition upon exposure to reduced temperatures for limited time, preferably 10 - 15 min at 140 - 150 °C. Different baffle and reinforcement elements with plastic carriers and thermally expandable compositions for automotive structural applications are for example known from US2011 / 0290585A1, KR1020080034493A, US6305136B1, US9381716B2, US9150001B2 and US6199940B1 with only general references to mechanical strength requirements and thermal properties.

[0010] Summary of the Invention

[0011] It is an object of the present invention to provide a baffle or reinforcement element containing a thermally expandable composition that allows for an improved expansion of the thermally expandable composition upon exposure to reduced temperatures for limited time, preferably 10 - 15 min at 140 - 150 °C.

[0012] Surprisingly, the present invention provides a solution to that problem by providing a baffle and / or reinforcement element comprising a thermally expandable composition TEC and a carrier element.

[0013] The carrier element consists of a plastic material MA with a thermal conductivity of more than 0.6 W / (mK), determined according to ASTM D5470.

[0014] The baffle and / or reinforcement element according to the present invention is particularly suitable to be used in automotive applications. 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

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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 of the present invention follow a radical mechanism.

[0019] Melt flow index (MFI) is determined by the ASTM D1238 standard method, using a capillary rheometer at 100 °C and a weight of 2.16 kg. 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.

[0020] Volume changes on the thermally expandable material are determined 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.

[0021] All industry standards and norms mentioned in the document refer to the versions valid at the date of first filing, unless stated otherwise. The carrier element can have any structure. For example, it can be solid or hollow or have a lattice-like structure. The surface of the carrier element can typically be smooth, rough or structured. The carrier element can also contribute to the structural reinforcement in addition to its function as a carrier for the thermally expandable composition TEC.

[0022] Preferably, the carrier element has a weight of more than 0.3 kg, preferably more than 0.6 kg, most preferably more than 1 kg. Especially such larger carrier elements with a higher mass take up significantly more heat energy during a heating process making it more difficult for the thermally expandable composition TEC to expand. Hence the current invention is especially suitable for such larger carrier elements.

[0023] It is further preferred if the carrier element has a maximal extension along its longitudinal axis of more than 0.2 meter, preferably more than 0.4 meter, most preferably more than 0.6 meter.

[0024] Preferably, the thermally expandable composition TEC is in direct contact with the carrier element. Preferably, 10 - 100 percent, more preferably 15 - 60 percent, most preferably 20 - 40 percent of the surface of the carrier element is in direct contact with the thermally expandable composition TEC. It is further preferable, if 50 - 100 percent, more preferably 75 - 100 percent, most preferably 90 - 100 percent of the surface of thermally expandable composition TEC, that is in contact with any other material than the surrounding air, is in direct contact with the carrier element.

[0025] The carrier element consists of a plastic material MA with a thermal conductivity of more than 0.6 W / (mK), determined according to ASTM D5470. The thermal conductivity requirement of more than 0.6 W / (mK) for the plastic carrier material provides a critical technical effect by enhancing heat transfer efficiency during the activation process of thermally expandable compositions. This elevated thermal conductivity enables rapid and uniform heat distribution throughout the carrier element, which acts as a thermal conduit to deliver activation energy more effectively to the thermally expandable composition TEC in contact with it. The enhanced heat transfer overcomes the thermal lag typically encountered with conventional low- conductivity plastic carriers, particularly in larger carrier elements where significant thermal mass can impede uniform heating. By facilitating faster temperature rise and more consistent thermal profiles across the carrier surface, this thermal conductivity threshold ensures reliable activation of the expandable material at reduced processing temperatures (140-150°C) and shorter cycle times (10-15 minutes), compared to conventional systems requiring higher temperatures or longer exposure times. The ASTM D5470 test method specification ensures reproducible measurement of this critical parameter, enabling precise material selection to achieve optimal thermal performance while maintaining the structural and processing advantages of plastic carrier materials over metallic alternatives.

[0026] Conventional Material Selection Practices

[0027] The skilled person in the field of baffle and reinforcement elements would not naturally select plastic materials with thermal conductivity above 0.6 W / (mK) for several technical and practical reasons rooted in established engineering practices. Standard engineering plastics used for structural carriers, including polyamides, polyesters, polyketones, and polyphenylene ethers, typically exhibit thermal conductivities in the range of 0.1-0.3 W / (mK) when unfilled. This conventional range has been deemed adequate for traditional carrier applications where the primary function is mechanical support and structural integrity rather than thermal performance. The skilled person would conventionally select materials within these established property ranges, as they represent proven solutions for carrier applications in automotive structural components.

[0028] Trade-offs with Mechanical Properties

[0029] Achieving thermal conductivity above 0.6 W / (mK) in plastic materials requires significant loading of thermally conductive fillers as for example graphite, carbon black, carbon nanotubes, or metallic powders. However, these fillers inherently compromise mechanical properties that are traditionally prioritized for structural carriers. The incorporation of thermally conductive fillers typically reduces impact strength, increases material brittleness, and may adversely affect tensile properties. The skilled person would typically avoid formulations that could compromise the mechanical integrity essential for baffle and reinforcement applications, particularly given the demanding automotive environment where carriers must withstand installation stresses, thermal cycling, and in-service mechanical loads. This creates a technical prejudice against high thermal conductivity formulations in favor of mechanically robust but thermally insulating materials.

[0030] Processing and Manufacturing Challenges

[0031] The higher filler F loadings necessary to achieve thermal conductivity above 0.6 W / (mK) create substantial processing and manufacturing challenges that would deter the skilled person from working in this range. Increased filler F content leads to higher melt viscosity, reduced flowability during injection molding, potential filler agglomeration, and increased wear on processing equipment. These processing difficulties can result in poor surface finish, dimensional instability, and increased manufacturing costs. Additionally, achieving uniform filler dispersion becomes increasingly challenging at higher loadings, potentially leading to property variations and quality control issues. The skilled person would typically select easier-to-process formulations with lower filler content to ensure reliable manufacturing and consistent part quality, particularly for complex geometries typical of baffle and reinforcement elements.

[0032] Cost Considerations and Economic Constraints

[0033] Thermally conductive fillers required to achieve conductivity above 0.6 W / (mK), particularly graphite, carbon nanotubes, and metallic powders, are significantly more expensive than conventional reinforcing fillers such as glass fibers or mineral fillers. The skilled person would typically minimize filler content to control material costs, especially in high-volume automotive applications where cost optimization is paramount. The economic pressure to use the minimum amount of expensive additives necessary to meet basic functional requirements would naturally lead the skilled person away from formulations with high thermal conductivity. Furthermore, the additional processing complexity and potential yield losses associated with highly filled systems would further increase the total cost of ownership, creating additional economic disincentives for working in the high thermal conductivity range.

[0034] Cross-Disciplinary Nature of the Solution

[0035] The present invention represents a cross-disciplinary approach that bridges traditionally separate fields of expertise: carrier design engineering and thermally expandable composition TEC chemistry. Skilled persons in carrier design typically focus on mechanical properties, structural performance, and manufacturing considerations, while those in expandable material chemistry concentrate on formulation, activation kinetics, and expansion characteristics. The insight that carrier thermal conductivity could be used to solve activation problems of thermally expandable compositions at reduced processing temperatures represents a non- obvious technical direction that transcends these traditional specialization boundaries. Prior art demonstrates that skilled persons have approached these as separate technical problems, with carrier thermal properties receiving minimal attention in the context of expandable material performance. This compartmentalized approach would not naturally lead to the recognition that enhanced carrier thermal conductivity above 0.6 W / (mK) could provide a solution to the industry need for lower temperature and shorter time activation of thermally expandable compositions.

[0036] Technical Challenges Overcome by the Invention

[0037] The present invention overcomes significant technical challenges that would discourage the skilled person from working in the thermal conductivity range above 0.6 W / (mK). The invention demonstrates that the apparent trade-off between thermal conductivity and mechanical properties can be successfully managed through careful material selection and property optimization. The specified ranges for tensile modulus (particularly 1-20 GPa), tensile strength (particularly 30-300 MPa), and charpy notched impact strength (particularly 2-25 kJ / m2) represent a carefully engineered balance that maintains adequate mechanical performance while achieving the required thermal conductivity. Furthermore, the invention addresses the processing challenges through specific filler selection criteria and loading ranges that enable reliable manufacturing while achieving the desired thermal performance. The unexpected technical effect of achieving 30-50% improvement in expandable material volume expansion at reduced temperatures (140°C for 7.5-10 minutes) compared to conventional carriers demonstrates that the benefits of enhanced thermal conductivity significantly outweigh the traditional concerns that would deter the skilled person from this approach.

[0038] Preferably, the plastic material MA has a thermal conductivity of more than 0.8 W / (mK), preferably more than 1.0 W / (mK), more preferably more than 1.1 W / (mK), determined according to ASTM D5470. This is advantageous with respect to a faster and more efficient expansion of the thermally expandable composition TEC upon exposure to heat, preferably 5 - 20 min at a temperature between 140 °C - 150 °C. This can be seen, for example, in the comparison of R1-R4 with E1-E8 in table 4. It is noteworthy that the substrate size of CA2 (E2, E4, E6 and E8) is larger than the substrate size of CAI (150 mm vs 120 mm in length). It is believed that the additional mass needed to heat up was responsible for the lower expansion rates of CA2 using RF1, BF1 and BF2 compared to CAI despite CA2 having a higher thermal conductivity.

[0039] It is further advantageous, if the plastic material MA has a specific heat capacity of less than 2500 J / (kgK), preferably less than 2250 J / (kgK), more preferably less than 2000 J / (kgK), determined according to ISO 11357-4 (as of September 2024). Most preferably, the plastic material MA has a specific heat capacity of 1000 - 2000 J / (kgK). This is advantageous with respect to a faster and more efficient expansion of the thermally expandable composition TEC upon exposure to heat, preferably 5 - 20 min at a temperature between 140 °C - 150 °C.

[0040] Specific Heat Capacity Requirements

[0041] The specific heat capacity limitation of less than 2500 J / (kgK) for the plastic material MA represents a parameter that has not been recognized or disclosed in the prior art for carrier materials in baffle and reinforcement applications. This parameter provides an additional thermal optimization mechanism that works synergistically with the thermal conductivity requirement to achieve superior performance in thermally expandable composition activation. Specific heat capacity, measured according to ISO 11357-4, quantifies the amount of thermal energy required to raise the temperature of a unit mass of material by one degree Kelvin. In the context of thermally expandable composition activation, a lower specific heat capacity means that the carrier material requires less thermal energy input to achieve the target activation temperature. This creates a more thermally responsive system where the carrier can rapidly reach and maintain the temperatures necessary for efficient expansion of the thermally expandable composition TEC.

[0042] The specified range of less than 2500 J / (kgK), preferably less than 2250 J / (kgK), more preferably less than 2000 J / (kgK), represents a carefully optimized balance that enables rapid thermal response while maintaining adequate thermal stability during processing and service conditions. The most preferred range of 1000-2000 J / (kgK) provides optimal thermal responsiveness for the intended application temperatures of 140-150°C over 5-20 minute exposure periods.

[0043] Synergistic Effect with Thermal Conductivity

[0044] The combination of high thermal conductivity (>0.6 W / (mK)) and controlled specific heat capacity (<2500 J / (kgK)) creates a synergistic thermal management system. While thermal conductivity facilitates rapid heat transfer through the carrier material, the controlled specific heat capacity ensures that the thermal energy is efficiently utilized for temperature rise rather than being stored as thermal mass. This dual optimization enables the carrier to act as an efficient thermal conduit that both rapidly conducts heat and quickly responds to temperature changes.

[0045] The specific heat capacity requirement directly impacts processing efficiency by reducing the thermal energy requirements for activation. Lower specific heat capacity materials reach target temperatures more quickly and with less energy input, enabling shorter cycle times and reduced processing temperatures. This is particularly advantageous for larger carrier elements where thermal mass effects become more pronounced. The reduced energy requirements also contribute to more uniform temperature distribution across the carrier surface, minimizing thermal gradients that could lead to non-uniform expansion of the thermally expandable composition.

[0046] The specific heat capacity requirement introduces an additional material selection criterion that may influence filler selection and polymer matrix choice. Different thermally conductive fillers exhibit varying specific heat capacities, and the optimization of both thermal conductivity and specific heat capacity may require careful selection of filler types and loadings. For example, metallic fillers may provide different thermal response characteristics compared to carbon-based fillers, even at equivalent thermal conductivity levels. The controlled specific heat capacity enables optimization of processing conditions by allowing for more precise thermal management. The reduced thermal inertia of low specific heat capacity carriers enables faster response to temperature changes, facilitating better control of activation timing and uniformity. This is particularly beneficial for achieving consistent expansion performance across varying part geometries and thermal exposure conditions.

[0047] Preferably, the plastic material MA has a tensile modulus @ 23 °C (ISO 527) of 1 - 20 GPa, more preferably 12.5 - 18 GPa, most preferably 14 - 16 GPa, and / or, preferably and; a tensile strength @ 23 °C (ISO 527) of 30 - 300 MPa, more preferably 75 - 250 MPa, most preferably 150 - 200 MPa, and / or, preferably and; a charpy notched impact strength @ 23°C (ISO 179) of 2 - 25 kJ / m2, more preferably 3 - 20 kJ / m2, most preferably 10 - 15 kJ / m2.

[0048] This is advantageous with respect to improved mechanical performance, especially if the element according to the invention is reinforcement element. The balance between tensile modulus (1-20 GPa), tensile strength (30-300 MPa), and charpy notched impact strength (2-25 kJ / m2) is crucial for optimal performance of the baffle and / or reinforcement element, as these properties must be carefully optimized to work synergistically with the thermal conductivity requirement. The tensile modulus provides the necessary structural stiffness to maintain dimensional stability during thermal expansion processes, while the tensile strength ensures adequate load - bearing capacity under mechanical stresses, and the charpy notched impact strength delivers essential fracture resistance to prevent brittle failure. This balanced property combination is particularly critical because thermally conductive fillers (such as graphite and metallic powders) that achieve the required thermal conductivity (>0.6 W / (mK)) can inherently increase material brittleness and reduce impact resistance. The specified ranges represent a carefully engineered compromise where sufficient thermal conductivity is achieved without compromising the mechanical integrity needed for reliable performance in demanding automotive applications. An imbalance in these properties— such as excessive modulus leading to brittleness, insufficient tensile strength causing mechanical failure, or inadequate impact strength resulting in crack propagation— would compromise the element's ability to function effectively as both a thermal conductor for expandable material activation and a structural component capable of withstanding installation stresses, thermal cycling, and in service mechanical loads throughout the vehicle's operational life. Charpy Notched Impact Strength Specification

[0049] The specification of charpy notched impact strength in the range of 2-25 kJ / m2, more preferably 3-20 kJ / m2, most preferably 10-15 kJ / m2, represents a critical and novel technical parameter that is completely absent from the prior art. This property specification addresses a fundamental challenge in thermally conductive carrier design that has not been recognized or solved in existing baffle and reinforcement technologies. The charpy notched impact strength, measured according to ISO 179, quantifies the material's ability to absorb energy during fracture in the presence of a stress concentrator, which is essential for predicting real-world performance under impact loading conditions typical in automotive applications.

[0050] The importance of this specification becomes particularly evident when considering that thermally conductive fillers required to achieve the thermal conductivity above 0.6 W / (mK) inherently tend to increase material brittleness and reduce impact resistance. Without proper control of the charpy notched impact strength, thermally conductive carriers would be prone to catastrophic brittle failure during handling, installation, thermal cycling, or in-service impact events. The specified range ensures that the carrier maintains sufficient fracture toughness to prevent crack initiation and propagation while still achieving the required thermal performance. This represents a breakthrough in materials engineering where the competing demands of thermal conductivity and impact resistance are successfully balanced through precise property specification.

[0051] Furthermore, the charpy notched impact strength specification is crucial for larger carrier elements (weight >0.3 kg and / or length >0.2 meter) where the combination of size, thermal conductivity requirements, and mechanical loading creates particularly demanding performance criteria. The energy absorption capability quantified by this test method ensures that the carrier can withstand the mechanical stresses encountered during automotive manufacturing processes, including e-coat operations, paint baking cycles, and final assembly operations, without compromising structural integrity. The complete absence of this critical parameter in the prior art demonstrates that previous approaches have failed to address this fundamental design challenge, making the present specification a significant technical advancement in thermally conductive carrier technology.

[0052] It is further advantageous, if the plastic material MA has a density determined according to DIN EN ISO 1183 of 0.8 - 1.8 kg / m3, preferably 1.0 - 1.7 kg / m3, more preferably 1.2 - 1.65 kg / m3. It is further preferred, if the plastic material MA comprises fibers, preferably selected from glass fibers, carbon fibers and aramid fibers, preferably selected from glass fibers and carbon fibers.

[0053] Preferably, the amount of fibers, based on the total weight of the material MA, is 20 - 50 wt.-%, more preferably 30 - 40 wt.-%, most preferably 32.5 - 37.5 wt.-%. This is advantageous with respect to improved mechanical performance, especially if the element according to the invention is a reinforcement element and the thermally expandable composition TEC is a thermally expandable composition TEC as described in claim 10 and / or claim 14. In case the element according to the invention is a baffle element and the thermally expandable composition TEC is a thermally expandable composition TEC as described in claim 11 and / or claim 13, it might be advantageous if the material MA is free of fibers.

[0054] Preferably, the plastic material MA comprises a thermally conductive filler. Preferably, the thermally conductive filler is selected from the group consisting of graphite; carbon black; carbon nanotubes; metallic powders, preferably aluminum powder, copper powder, bronze powder and brass powder; metal oxide, preferably zinc oxide, magnesium oxide, beryllium oxide, zirconium oxide; preferably the conductive filler is selected from graphite and metallic powders.

[0055] It is advantageous, if the amount of said thermally conductive filler is 2 - 85 wt.-%, more preferably 3 - 50 wt.-%, most preferably 5 - 35 wt.-%, based on the total weight of the plastic material MA.

[0056] If the element according to the invention is a reinforcement element and the thermally expandable composition TEC is a thermally expandable composition TEC as described in claim 10 and / or claim 14, it might be advantageous if the amount of thermally conductive filler is 5 - 15 wt.-%, based on the total weight of the plastic material MA.

[0057] In case the element according to the invention is a baffle element and the thermally expandable composition TEC is a thermally expandable composition TEC as described in claim 11 and / or claim 13, it might be advantageous if the amount of thermally conductive filler is 10 - 35 wt.-%, based on the total weight of the plastic material MA.

[0058] It is further preferred if the plastic material MA comprises a thermoplastic material as a matrix. Preferably, the plastic material MA comprises a polymer selected from the group consisting of polyamides, polyesters, especially polyetylene terephthalates and polybutylene terephthalates, polyketones, polyphenylene ethers, polysulfones and polyethersulfones, preferably polyamides. It is advantageous, if the amount of said polymer is 30 - 90 wt.-%, more preferably 40 - 85 wt.-%, most preferably 50 - 80 wt.-%, based on the total weight of the plastic material MA.

[0059] If the element according to the invention is a reinforcement element and the thermally expandable composition TEC is a thermally expandable composition TEC as described in claim 10 and / or claim 14, it might be advantageous if the amount of said polymer is 45 - 65 wt.-%, based on the total weight of the plastic material MA.

[0060] In case the element according to the invention is a baffle element and the thermally expandable composition TEC is a thermally expandable composition TEC as described in claim 11 and / or claim 13, it might be advantageous if the amount of said polymer is 65 - 90 wt.-%, based on the total weight of the plastic material MA.

[0061] The baffle and / or reinforcement element comprises a thermally expandable composition TEC. Preferably, said thermally expandable composition TEC comprises at least one blowing agent BA, preferably selected from azodicarbonamide and 4,4'- oxybis (benzenesulphonylhydrazide).

[0062] 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 expandable composition TEC

[0063] A suitable blowing agent may be a chemical or physical blowing agent. Preferably, the at least one blowing agent BA is a chemical blowing agent.

[0064] The at least one physical or chemical blowing agent BA preferably has an activation temperature from 120 °C to 220 °C, preferably from 140 °C to 200 °C.

[0065] 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.

[0066] 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-l,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.

[0067] 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).

[0068] Preferably, the thermally expandable composition TEC is selected from the group consisting of epoxy resin compositions, polyurethane compositions and compositions containing at least one polymer P that is cross-linkable by peroxide.

[0069] In a preferred aspect of the invention, the thermally expandable composition TEC is a composition containing at least one polymer P that is cross-linkable by peroxide. This selection is especially preferred if the element according to the invention is a baffle element.

[0070] As said polymer P 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.

[0071] 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.

[0072] The copolymers, meaning polymers made from more than one type of monomer, can be block type copolymers or random copolymers.

[0073] Polymers P can also be further functionalised, meaning they can contain further functional groups such as hydroxyl, carboxy, anhydride, acrylate, and / or glycidylmethacrylate groups.

[0074] 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.

[0075] 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. 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.

[0076] 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.

[0077] The thermally expandable 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.

[0078] Preferred EVA polymers include, e.g., Elvax® 150, Elvax® 240A, Elvax® 260A, Elvax® 420A (all by DuPont), or the corresponding Evatane® copolymers (by Arkema).

[0079] A second preferred component of the thermally expandable composition containing the polymer P is at least one acrylate A,

[0080] 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.

[0081] Acrylate A preferably has a molecular weight of less than 2'500 g / mol, more preferably less than 1'000 g / mol.

[0082] 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.

[0083] Although polymer P (described above) can comprise acrylate functions, it is beneficial for the inventive 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.

[0084] 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.

[0085] Preferred acrylates A with a functionality of 3 or higher include glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetraacrylate, Di-(trimethylolpropane) tetraacrylate, pentraerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tri(2 -methacryloxyethyl) trimellitate, tri(2-acryloxyethyl) isocyanurate, as well as their ethoxylated or propoxylated derivates.

[0086] Especially preferred acrylates A exhibit a functionality of 5, such as dipentaerythritol pentaacrylate.

[0087] 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.

[0088] A third preferred component of the thermally expandable composition containing the polymer P is at least one peroxide PE.

[0089] The thermally expandable composition containing the polymer P 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.

[0090] 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.

[0091] The fourth preferred component of the composition containing the polymer P is a blowing agent BA as mentioned above.

[0092] Preferably, the blowing agent BA is included in the composition with an amount of between 3 and 15 wt.-%, preferably between 5 and 10 wt.-%, more preferably between 7 and 9.5 wt.-%, based on the total weight of the composition.

[0093] Preferably, the composition containing the polymer P comprises:

[0094] - at least one polymer P, cross-linkable by peroxide, preferably between 30 and 80 wt.-%, based on the total weight of the composition, and; - preferably at least one acrylate A, preferably between 0.1 and 5 wt.-%, based on the total weight of the composition, and;

[0095] - at least one peroxide PE and;

[0096] - at least one blowing agent BA, preferably selected from azodicarbonamide and 4,4'-oxybis(benzenesulphonylhydrazide, preferably between 3 and 15 wt. -%, based on the total weight of the composition.

[0097] Apart from said ingredients, the composition containing the polymer P 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.

[0098] In another preferred aspect of the invention, the thermally expandable composition TEC is an epoxy resin composition, more preferably a thermosetting one-component epoxy resin composition. This selection is especially preferred if the element according to the invention is a reinforcement element.

[0099] Most preferably, the one-component thermosetting epoxy resin composition comprises:

[0100] - 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

[0101] - at least one latent hardener B for epoxy resins; and

[0102] - preferably at least one accelerator C for epoxy resins; and

[0103] - 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;

[0104] - 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.

[0105] 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.

[0106] 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.

[0107] Preferred epoxy resins have the formula (I)

[0108] In this formula, the substituents R’ and R” independently of one another are either H or CH3.

[0109] In solid epoxy resins, the index s has a value of > 1 .5, more particularly from 2 to 12.

[0110] Solid epoxy resins of this kind are available commercially, for example, from Dow or Huntsman or Hexion.

[0111] 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.

[0112] 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.

[0113] 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).

[0114] Of further suitability as epoxy resin A are what are called epoxy novolacs. These compounds have, in particular, the following formula:

[0115] More particularly these are phenol-epoxy or cresol-epoxy novolacs (R2 = CH2).

[0116] 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.

[0117] The epoxy resin A is preferably a solid epoxy resin of the formula (I).

[0118] 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.-%.

[0119] 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.

[0120] The latent hardener B is preferably selected from dicyandiamide, guanamines, guanidines, aminoguanidines and derivatives thereof, substituted ureas, imidazoles and amine complexes, preferably dicyandiamide.

[0121] 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.

[0122] 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.

[0123] The thermosetting one-component epoxy resin composition preferably further comprises at least one accelerator C for epoxy resins. Such accelerating curing agents are preferably substituted ureas, for example 3-(3- chloro-4-methylphenyl)-1 ,1 -dimethylurea (chlortoluron) or phenyldimethylureas, especially p-chlorophenyl-N,N-dimethylurea (monuron), 3-phenyl-1 ,1 -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-hydroxyphenyl)-4,5-dihydroimidazol-1 -yl)ethyl)benzamide, imidazolines, trihalide complexes, preferably BF3 complexes, blocked amines and encapsulated amines.

[0124] Preferably, the accelerator C for epoxy resins is selected from the list consisting of substituted ureas, imidazoles, imidazolines and blocked amines, preferably substituted ureas.

[0125] The one-component thermosetting epoxy resin composition comprises at least one toughness improver D. The toughness improvers D may be solid or liquid.

[0126] More particularly the toughness improver D is selected from the group consisting of terminally blocked polyurethane polymers D1 , 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 D1 and liquid rubbers D2, most preferably liquid rubbers D2.

[0127] 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.

[0128] Such carboxyl group containing acrylonitrile / butadiene rubbers ABR may also include pendant carboxy or carboxyl groups.

[0129] The carboxyl group containing acrylonitrile / butadiene rubbers ABR preferably have a carboxyl content of 0.005 equivalents per hundred rubber (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.

[0130] 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.

[0131] 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. 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.

[0132] 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.

[0133] 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".

[0134] 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.

[0135] 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 fibres and colour pigments. Particularly preferred are fillers selected from the group consisting of calcium carbonate, calcium oxide, talc, glass fibres, hollow glass beads and fumed silicas, more preferably talc, glass fibres, hollow glass beads, calcium carbonate and fumed silicas.

[0136] 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.

[0137] 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. 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.

[0138] It is further preferred, if the one-component thermosetting epoxy resin composition show the following adhesion and mechanical properties:

[0139] - Tensile strength: >3 MPa, preferably >4 MPa, more preferably >5 MPa; and / or, preferably and

[0140] - Modulus: >400 MPa, preferably >500 MPa, more preferably >600 MPa; and / or, preferably and

[0141] - Elongation at break: 0.5 - 2 %, preferably 0.75 - 1.5 %, more preferably 1 - 1.25 %.

[0142] In one aspect of the invention, it is preferred if the thermally expandable composition TEC has an expansion rate of 60% - 600%, preferably 100% - 500%, more preferably 150% - 300%. This selection is especially preferred if the element according to the invention is a reinforcement element and / or the thermally expandable composition TEC is an above mentioned one-component thermosetting epoxy resin composition.

[0143] In one aspect of the invention, it is preferred if the thermally expandable composition TEC has an expansion rate of 800% - 4000%, preferably 900% - 3000%, more preferably 1000% - 2500%. This selection is especially preferred if the element according to the invention is a baffle element and / or the thermally expandable composition TEC is an above mentioned composition comprising at least one polymer P, cross-linkable by peroxide.

[0144] The above-mentioned expansion rate is preferably determined by heating the thermally expandable composition TEC for 30 minutes at 180 °C and determining the expansion rate by DIN EN ISO 1183 (as of September 2024).

[0145] The thermally expandable composition TEC 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.

[0146] 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 blowing agent BA. 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.

[0147] 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.

[0148] The expansion of the thermally expandable composition TEC is triggered by heat. Preferably, the activation temperatures for the thermally expandable composition are in the range of 130 °C to 250 °C, preferably 150 °C to 200 °C, and require a dwell time of between 10 and 90 min, preferably between 15 and 60 min.

[0149] The baffle and / or reinforcement element comprising the carrier element and the thermally expandable composition TEC is preferably produced by injection molding.

[0150] Preferably, a two-component injection molding process is used. First, a first component, in this case the carrier element, is injected. After this first component has solidified, the cavity in the mold is enlarged or adapted, or the molded part is placed in a new mold, and a second component, in this case the thermally expandable composition TEC, is molded onto the first component with a second injection unit.

[0151] Furthermore, the invention comprises the use of a baffle and / or reinforcement element, as described above, for baffling and reinforcing cavities in structural components. Structural components of this type are preferably used in bodies and / or frames of means of transport and transportation, in particular of vehicles on water or on land or of aircraft. The invention preferably includes the use of a baffle and / or reinforcement element according to the invention in bodies or frames of automobiles (in particular A, B, C or D pillars) trucks, railroad cars, boats, ships, helicopters and airplanes, mostly preferably in automobiles.

[0152] A further aspect of the present invention therefore relates to a method for baffling and / or reinforcing a structural component comprising the steps i) placing the baffle and / or reinforcement element in a cavity according to the previous description; ii) heating the baffle and / or reinforcement element to a temperature from 120 °C to 220 °C, preferably from 140 °C to 200 °C, preferably for 10 to 60 min.

[0153] Preferably, step i) takes place before step ii).

[0154] Hence another aspect of the present invention is the use of a carrier element, wherein the carrier element consists of a plastic material MA with a thermal conductivity of more than 0.6 W / (mK), determined according to ASTM D5470, as described before, for increasing the volume expansion of a thermally expandable composition TEC as mentioned before in direct contact with the carrier element.

[0155] This is compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK). The volume expansion is determined after curing the thermally expandable composition TEC at a temperature of 140 - 150 °C for 5 - 20 min.

[0156] The volume expansion is preferably determined by DIN EN ISO 1183 (as of September 2024). More preferably, a sample of the thermally expandable composition TEC with the dimension 25 mm x 25 mm x 3 mm is placed on a sample of the plastic material MA with the dimension 120 mm x 150 mm x 3 mm and the received specimen is exposed the indicated temperature for the indicated time. The volume expansion is then determined by DIN EN ISO 1183.

[0157] In one preferred aspect, the volume expansion is determined after curing the thermally expandable composition TEC, preferably a one-component thermosetting epoxy resin composition as mentioned above, at a temperature of 140 °C for 7.5 min, and the volume expansion is more than 30 %, preferably more than 50 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK); and / or, preferably and, the volume expansion is determined after curing the thermally expandable composition TEC at a temperature of 140 °C for 10 min, and the volume expansion is more than 10 %, preferably more than 20 %, preferably more than 30 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK). This aspect demonstrates a significant technical advancement by achieving substantially improved expansion performance of thermally expandable compositions at reduced processing temperatures and shorter cycle times. The thermally conductive carrier (>0.6 W / (mK)) enables more than 30- 50% greater volume expansion compared to conventional carriers (<0.6 W / (mK)) when cured at only 140°C for 7.5 minutes, and maintains 10-30% superior expansion even at the extended 10-minute cycle. This represents a breakthrough in addressing the automotive industry's critical need for lower energy consumption and faster processing cycles, as it allows effective activation of expandable compositions at temperatures significantly below traditional requirements (typically 180-200°C for 20- 30 minutes) while maintaining or improving performance. The enhanced heat transfer through the thermally conductive carrier overcomes the thermal lag typically experienced with larger carrier elements, ensuring uniform and complete curing of the expandable material even under reduced time-temperature conditions, thereby enabling OEMs to reduce energy costs, increase production throughput, and meet sustainability targets without compromising structural reinforcement or sealing performance.

[0158] In another preferred aspect, the volume expansion is determined after curing the thermally expandable composition TEC, preferably a composition comprising at least one polymer P, cross-linkable by peroxide as mentioned above, at a temperature of 150 °C for 10 min, preferably as described in the description, and the volume expansion is more than 300 %, preferably more than 450 %, more preferably more than 700 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK); and / or, preferably and, wherein the volume expansion is determined after curing the thermally expandable composition TEC at a temperature of 140 °C for 15 min, preferably as described in the description, and the volume expansion is more than 150 %, preferably more than 200 %, more preferably more than 230 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK).

[0159] In one preferred aspect, the structural component is selected from bodies and frames of automobiles, trucks, railroad cars, boats, ships, helicopters, and airplanes.

[0160] In one preferred aspect, wherein the heating step is performed at a temperature from 140°C to 200°C for 15 to 60 minutes.

[0161] Examples

[0162] Raw materials and test methods used for the testing of the respective properties in the examples were as follows:

[0163] Carrier materials CAR, CA1 and CA2

[0164] Table 1

[0165] Reinforcing compositions 1 and 2 (RF1 and RF2)

[0166] Table 2

[0167] Preparation of the compositions

[0168] According to the information in table 2, the compositions RF1 and RF 2 were produced. The amounts in Table 2 are in parts by weight. The raw materials used were mixed with a tumble mixer for 10 min. The mixtures were introduced into a twin-screw extruder (Dr. Collin ZK 25 T SCD15) and compounded at a throughput of 2.5 kg per hour. The discharge took place through a 1 -hole nozzle (3mm) on a conveyor belt. The strand obtained was cooled with forced air and then granulated using the Dr. Collin granulator integrated in the system. The granules obtained were then processed into 3 mm thick sheets using a Krauss-Maffei 110t injection molding machine. Table 3 - Baffling compositions 1 and 2 (BF1 and BF2)

[0169] Preparation of the compositions

[0170] According to the information in table 3, the compositions BF1 and BF2 were produced. The amounts in Table 3 are in parts by weight. The compositions were produced on standard production equipment suitable to compound thermoplastics with temperature control, i.e. twin screw extruder, Buss kneader or Banbury mixer. Polymers were mixed until homogeneous, then the system was cooled below activation of heat reactive raw materials. Heat reactive raw materials were then mixed into the system until homogeneous. Material was subsequently shape formed while hot into sample shapes that were used for expansion testing procedures. The following measurements were carried out on the test specimens obtained:

[0171] Test Methods:

[0172] Melt flow index (MFI)

[0173] 100 ° C, 2.16 kg according to ASTM D1238

[0174] The MFI was determined using a capillary rheometer, whereby the granules were first melted in a heatable cylinder with a melting time of 120 seconds, compressed and pressed under a pressure nozzle (weight) through a defined nozzle (2,046mm). The emerging mass of the polymer melt was determined. This was then weighed out on an analytical balance and the MFI was calculated using the appropriate formula (MFI = mass 1 10min). The unit for the MFI is therefore given in g / 10min.

[0175] Determination of volume expansion (expansion)

[0176] For the carrier materials CAR and CA1 , a sample with the dimension of 120 mm x 150 mm x 3 mm was used. For the materials CA2, a sample with the dimension 150 mm x 150 mm x 3 mm was used. On the carrier sample, the in table 4 indicated thermally expandable composition (composition) RF1 , RF2, BF1 or BF2 with the dimension 25 mm x 25 mm x 3 mm was added on top. The received specimens were put into an oven with the temperature indicated in table 4 (140 °C, 150 °C respectively) and kept in the oven for the indicated time and then removed.

[0177] The expansion was determined in all specimens. The temperatures, time periods and extent of expansion (in % based on the original volume before expansion) are shown in Table 4. “Expansion” indicates the % of expansion based on the original volume before expansion. “Expansion compared to expansion after 20 min (%)” indicates the % of expansion based on the volume expansion value after 20 min. “Expansion compared to CAR” indicates the factor of expansion based on the volume expansion value of the corresponding CAR sample of the same bake time. For example, the value for E1 after a bake time of 5 min is a factor of 2.4, which corresponds to the volume expansion of 83 % for CA1 (E1 ) divided by the volume expansion of CAR of 35 % (R1 ).

[0178] Volume expansions were quantified for each specimen by measuring the density before and after expansion. The densities were determined according to DIN EN ISO 1183 using the water immersion method (Archimedes principle) in deionized water and a precision balance to measure the mass. All the compositions R1 -R4 and E1-E8 before expansion were tack-free at 23°C according to the definition described above and had an MFI of between 1 and 25 g / 10min. Table 4

Claims

CLAIMS1. A baffle and / or reinforcement element comprising a thermally expandable composition TEC and a carrier element, wherein the carrier element consists of a plastic material MA with a thermal conductivity of more than 0.6 W / (mK), determined according to ASTM D5470.

2. The baffle and / or reinforcement element according to claim 1, wherein the plastic material MA has a specific heat capacity of less than 2500 J / (kgK), preferably less than 2250 J / (kgK), more preferably less than 2000 J / (kgK), determined according to ISO 11357-4.

3. The baffle and / or reinforcement element according to any of the preceding claims, wherein the plastic material MA has a tensile modulus @ 23 °C (ISO 527) of 1 - 20 GPa and / or, preferably and, a tensile strength @ 23 °C (ISO 527) of 30 - 300 MPa and / or, preferably and, a charpy notched impact strength @ 23°C (ISO 179) of 2 - 25 kJ / m2.

4. The baffle and / or reinforcement element according to any of the preceding claims, wherein the plastic material MA has a thermal conductivity of more than 0.8 W / (mK), preferably more than 1.0 W / (mK), more preferably more than 1.1 W / (mK), determined according to ASTM D5470.

5. The baffle and / or reinforcement element according to any of the preceding claims, wherein the plastic material MA comprises a polymer selected from the group consisting of polyamides, polyesters, especially polyetylene terephthalates and polybutylene terephthalates, polyketones, polyphenylene ethers, polysulfones and polyethersulfones, preferably polyamides.

6. The baffle and / or reinforcement element according to any of the preceding claims, wherein the plastic material MA has a density determined according to DIN EN ISO 1183 of 0.8 - 1.8 kg / m3, preferably 1.0 - 1.7 kg / m3, more preferably 1.2 - 1.65 kg / m3.

7. The baffle and / or reinforcement element according to any of the preceding claims, wherein the plastic material MA comprises fibers, preferably selected from glass fibers, carbon fibers and aramid fibers, preferably 20 - 50 wt.-%, more preferably 30 - 40 wt.-%, most preferably 32.5 - 37.5 wt.-% fibers, based on the total weight of the material MA.

8. The baffle and / or reinforcement element according to any of the preceding claims, wherein the plastic material MA comprises a thermally conductive filler, preferably selected from the group consisting of graphite; carbon black; carbonnanotubes; metallic powders, preferably aluminum powder, copper powder, bronze powder and brass powder; metal oxide, preferably zinc oxide, magnesium oxide, beryllium oxide, zirconium oxide; most preferably selected from graphite and metallic powders.

9. The baffle and / or reinforcement element according to any of the preceding claims, wherein the thermally expandable composition TEC is in direct contact with the carrier element.

10. The baffle and / or reinforcement element, preferably reinforcement element, according to any of the preceding claims, wherein the thermally expandable composition TEC has an expansion rate of 60% - 600%, preferably 100% - 500%, more preferably 150% - 300%, determined by heating the thermally expandable composition TEC for 30 minutes at 180 °C and determining the expansion rate by DIN EN ISO 1183.

11. The baffle and / or reinforcement element preferably baffle element, according to any of the claims 1 - 9, wherein the thermally expandable composition TEC has an expansion rate of 800% - 4000%, preferably 900% - 3000%, more preferably 1000% - 2500%, ddetermined by heating the thermally expandable composition TEC for 30 minutes at 180 °C and determining the expansion rate by DIN EN ISO 1183.

12. The baffle and / or reinforcement element according to any of the preceding claims, wherein the thermally expandable composition TEC is selected from the group consisting of epoxy resin compositions, polyurethane compositions and compositions containing at least one polymer P that is cross-linkable by peroxide.

13. The baffle and / or reinforcement element, preferably baffle element, according to any of the preceding claims, wherein the thermally expandable composition TEC comprises:- at least one polymer P, cross-linkable by peroxide, preferably between 30 and 80 wt.-%, based on the total weight of the composition, and;- preferably at least one acrylate A, preferably between 0.1 and 5 wt.-%, based on the total weight of the composition, and;- at least one peroxide PE and;- at least one blowing agent BA, preferably selected from azodicarbonamide and 4,4'-oxybis(benzenesulphonylhydrazide, preferably between 3 and 15 wt.-%, based on the total weight of the composition.

14. The baffle and / or reinforcement element, preferably reinforcement element, according to claim 1 - 12, wherein the thermally expandable composition TEC is a one-component thermosetting epoxy resin composition comprising:- 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- at least one latent hardener B for epoxy resins; and- preferably at least one accelerator C for epoxy resins; and- 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;- at least one blowing agent BA, preferably selected from azodicarbonamide and 4,4'-oxybis(benzenesulphonylhydrazide, preferably between 0.1 and 5 wt.-%, based on the total weight of the one-component thermosetting epoxy resin composition.

15. The baffle and / or reinforcement element according to any of the preceding claims, wherein the carrier element has a weight of more than 0.3 kg, preferably more than 0.6 kg, most preferably more than 1 kg.

16. A method for baffling or reinforcing a structural component comprising the steps i. placing a baffle and / or reinforcement element according to claim 1 - 15 in a cavity of a structural component, preferably in bodies and / or frames of means of transport and transportation; ii. heating the baffle and / or reinforcement element to a temperature from 120 °C to 220 °C, preferably from 140 °C to 200 °C, preferably for 10 to 60 min.

17. Use of a carrier element, wherein the carrier element consists of a plastic material MA with a thermal conductivity of more than 0.6 W / (mK), determined according to ASTM D5470, as described in any of the claims 1 - 15, for increasing the volume expansion of a thermally expandable composition TEC as mentioned in any of the claims 1 - 15 in direct contact with the carrier element, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK),wherein the volume expansion is determined after curing the thermally expandable composition TEC at a temperature of 140 - 150 °C for 5 - 20 min, preferably volume expansion is determined by DIN EN ISO 1183.

18. Use according to claim 17, wherein the volume expansion is determined after curing the thermally expandable composition TEC, preferably as described in claim 14, at a temperature of 140 °C for 7.5 min, preferably as described in the description, and the volume expansion is more than 30 %, preferably more than 50 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK); and / or, preferably and, wherein the volume expansion is determined after curing the thermally expandable composition TEC at a temperature of 140 °C for 10 min, preferably as described in the description, and the volume expansion is more than 10 %, preferably more than 20 %, preferably more than 30 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK).

19. Use according to claim 17, wherein the volume expansion is determined after curing the thermally expandable composition TEC, preferably as described in claim 13, at a temperature of 150 °C for 10 min, preferably as described in the description, and the volume expansion is more than 300 %, preferably more than 450 %, more preferably more than 700 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK); and / or, preferably and, wherein the volume expansion is determined after curing the thermally expandable composition TEC at a temperature of 140 °C for 15 min, preferably as described in the description, and the volume expansion is more than 150 %, preferably more than 200 %, more preferably more than 230 %, compared to a carrier element consisting of a plastic material MA with a thermal conductivity of less than 0.6 W / (mK).

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