Thermally expandable compositions with improved moisture storage resistance

Abstract

The present invention relates to a thermally expandable composition comprising at least one polymer, at least one free radical initiator, at least one chemical blowing agent, and a silane group. The present invention also relates to a barrier and / or reinforcing element for a hollow structure comprising the thermally expandable composition, a method for manufacturing the barrier and / or reinforcing element, the use of the barrier and / or reinforcing element for sealing, blocking, or reinforcing a cavity or a hollow structure, and a method for sealing, blocking, and / or reinforcing a cavity or a hollow structure.

Description

Technical Field

[0001] The present invention relates to thermally expandable compositions and their use for providing baffles and / or reinforcing elements. Such elements are particularly suitable for sealing, blocking and / or reinforcing hollow structures, such as cavities in hollow structural parts of automotive vehicles. Background of the Invention

[0003] Manufactured products often contain holes and cavities or other hollow parts that are created by the manufacturing process and / or are designed into the product for various purposes, such as weight reduction. An automotive vehicle, for example, includes several such holes and cavities throughout the vehicle, including those in the vehicle's structural pillars and in the sheet metal of the vehicle's doors. It is often desirable to seal such holes and cavities, thereby minimizing the transfer of noise, vibration, smoke, dust, water, moisture, etc., from one area within the vehicle to another by means of sealing members or baffle elements built into the holes or cavities. Likewise, such members or elements often fulfill the additional task of reinforcing the hollow structure of a manufactured product (e.g., an automotive part), making it more resistant to mechanical stresses while still retaining the low weight advantages of the hollow structure.

[0004] Such elements for sealing, blocking or reinforcing generally consist of a carrier made of plastic, metal or another rigid material and one or more layers of thermoplastic material attached to the carrier, the thermoplastic material being able to expand its volume when heat or another physical or chemical form of energy is applied, but they can also be made entirely of expandable material. Using an appropriate design, it is possible to insert the baffle or reinforcing element into a hollow part of a structure during the manufacturing process, while still leaving the inner wall of the structure accessible, for example, to a liquid (or permeable through the cavity). For example, during the manufacturing process of a vehicle, the hollow part of the metal frame can still be largely covered with the electrophoretic coating ("e-coat") liquid when the baffle or reinforcing element has been inserted, and then, during a baking step, the expandable thermoplastic material of the baffle or reinforcing element expands to fill the cavity as intended.

[0005] The development of such baffles or reinforcement elements has led to highly advanced systems in which expandable materials are able to increase their volume by up to several thousand percent, forming a stable, cross-linked foam-like structure that fills the cavity and adheres to the walls of the structure to be sealed, blocked or reinforced. This has led to considerable weight savings and excellent noise and vibration damping in the vehicle body, particularly in automotive construction.

[0006] The currently used heat-expandable compositions are generally composed of polymers, such as ethylene-vinyl acetate polymers, which can be cross-linked by free radical initiators, most commonly peroxides. In order to obtain foam, these compositions also contain blowing agents, the most widely used of which are azodicarbonamide (also known as diazoldicarbonamide or azobiscarbonamide) and 4,4'-oxybenzenesulfonylhydrazine (abbreviation OBSH). Under activation conditions such as elevated temperatures, the crosslinkable network solidifies, while the blowing agent decomposes and releases gas. This results in the above-mentioned volume expansion and the formation of stable foam, which ideally fills the cavity as expected and adheres to its walls. Such systems are for example disclosed in DE 10 2011 080 223 A1.

[0007] However, prior to stable foam expansion and formation, known heat-expandable compositions are particularly susceptible to moisture and therefore have rather limited storage stability. For example, water absorbed into the composition during storage under humid conditions can react with free radical initiators to reduce crosslink density, leading to loss of expansion and the formation of an open cell structure. Furthermore, the lower expansion rate and open cell structure reduce the sealing ability of the material.

[0008] It would therefore be desirable to obtain thermally expandable compositions with improved moisture storage resistance, ie compositions which exhibit reduced loss of expansion after storage under humid conditions at elevated temperature. SUMMARY OF THE INVENTION

[0010] The object of the present invention is to provide a thermally expandable composition which is capable of uniformly expanding and curing over a wide temperature range to form a stable foam structure and which exhibits improved stability towards water / humidity. Furthermore, the foam produced should exhibit good adhesion to metals, even oily surfaces, and other substrates commonly used in the manufacture of articles, in particular automotive vehicles.

[0011] The subject of the present invention is a thermally expandable composition as defined in claim 1 .

[0012] Surprisingly found that the compound with hydrolyzable silane group can be used for improving the moisture storage resistance of heat-expandable composition.Not bound by any theory, it is believed that a small amount of silane group and water reaction during moisture storage, this causes the partial crosslinking of polymer chain before the curing step.In addition, at least a portion of silane group reacts with the water that material absorbs during moisture storage during the curing process, causes the further crosslinking of polymer chain.The silane crosslinking reaction that occurs during moisture storage or the curing step process compensates for the network density loss caused by reacting for example between the water and free radical crosslinking agent absorbed by peroxide.

[0013] One of the advantages of the thermally expandable composition of the present invention is that the moisture storage resistance can be improved without negatively affecting other application-relevant properties of the thermally expandable composition.The desired effect can also be achieved by using relatively small amounts of compounds containing hydrolyzable silane groups.

[0014] Further subject-matter of the invention is presented in the other independent claims. Preferred aspects of the invention are presented in the dependent claims. Detailed Description of the Invention

[0016] The subject of the present invention is a thermally expandable composition comprising:

[0017] a) at least one polymer P,

[0018] b) at least one free radical initiator I, and

[0019] c) at least one chemical blowing agent CBA, and

[0020] d) optionally at least one epoxy-functional polymer EP,

[0021] Wherein the composition comprises a silane group of formula (I)

[0022]

[0023] where R 1 represents an alkyl group having 1 to 8 carbon atoms, preferably 1 to 5 carbon atoms,

[0024] R 2 represents an alkyl group having 1 to 8 carbon atoms, preferably 1 to 5 carbon atoms, and the index a has a value of 0, 1 or 2, preferably 0 or 1.

[0025] The term "polymer" refers to a chemically homogeneous collection of macromolecules resulting from a polymerization reaction (polymerization, polyaddition, polycondensation), wherein the macromolecules differ in their degree of polymerization, molecular weight and chain length. The term also includes derivatives of said collection of macromolecules resulting from a polymerization reaction, i.e. compounds obtained by reaction of predetermined functional groups in the macromolecules, such as addition or substitution, which may be chemically homogeneous or chemically heterogeneous.

[0026] The term "silane" designates compounds which, in the first instance, have at least one, typically two or three, hydrolyzable groups, more particularly alkoxy or acyloxy groups, bonded directly to a silicon atom via an Si—O bond, and, in the second instance, at least one organic group bonded directly to a silicon atom via an Si—C bond. Silanes having alkoxy or acyloxy groups are also known to those skilled in the art as organoalkoxysilanes and organoacyloxysilanes, respectively. Thus, tetraalkoxysilanes are not silanes under this definition.

[0027] Accordingly, the term "silane group" designates a silicon-containing group bonded to an organic carbon group via a Si-C bond. Silanes and their silane groups have the property of hydrolyzing upon contact with moisture. In doing so, they form organosiliconols (organosilicon compounds containing one or more silanol groups (Si-OH groups)) and, through a subsequent condensation reaction, organosiloxanes (organosilicon compounds containing one or more siloxane groups (Si-O-Si groups)).

[0028] The terms "silane-functionalized" and "silane-functionalized" designate compounds containing silane groups. The terms "silane-functionalized polymer" and "silane-functionalized polymer" therefore designate polymers containing at least one silane group.

[0029] The term "molecular weight" refers to the molar mass (g / mol) of a molecule or a portion of a molecule (also called a "moiety"). The term "average molecular weight" refers to the number average molecular weight (M) of a mixture of oligomers or polymers of a molecule or moiety. n The molecular weight can be determined by conventional methods, preferably by gel permeation chromatography (GPC) using polystyrene as a standard, styrene-divinylbenzene gel with pores of 100 angstroms, 1000 angstroms and 10000 angstroms as a column and tetrahydrofuran as a solvent at 35°C.

[0030] The term "softening point" or "softening temperature" designates the temperature at which a compound softens into a rubbery state or the temperature at which crystalline parts within a compound melt. The softening point can be measured by the ring and ball method defined in the DIN EN 1238 standard.

[0031] The term "melting temperature" refers to the temperature at which a material undergoes a transition from a solid to a liquid state. The melting temperature (T m ). The measurement can be performed using a Mettler Toledo DSC 3+ device and T m The value can be determined from the measured DSC curve with the aid of DSC software. If the measured DSC curve shows several peak temperatures, the first peak temperature from the lower temperature side in the thermogram is taken as the melting temperature (T m ).

[0032] The "amount or content of at least one component X" in a composition, for example, the "amount of at least one polymer P", refers to the sum of the individual amounts of all polymers P present in the composition. For example, if the at least one polymer P represents 20% by weight of the total weight of the composition, then the sum of the amounts of all polymers P present in the composition is equal to 20% by weight.

[0033] The term "room temperature" refers to a temperature of 23°C.

[0034] The amount of silane groups of formula (I) in the heat-expandable composition is not particularly limited. However, it has been found that a minimum amount of moisture-reactive groups is required to have improved moisture resistance, and that increasing the amount of silane groups above a certain limit results in a decrease in the initial expansion rate before storage in moisture, particularly at higher temperatures above 185°C.

[0035] According to one or more preferred embodiments, the thermally expandable composition comprises 0.05-10.0 wt. %, preferably 0.15-7.5 wt. %, more preferably 0.20-5.0 wt. %, even more preferably 0.25-3.5 wt. % of silane groups of formula (I), based on the total weight of the thermally expandable composition. It has been found that adding silane groups to the thermally expandable composition in an amount falling within the above defined range results in a substantial improvement in moisture storage stability. In particular, such a thermally expandable composition exhibits significantly lower expansion loss when stored at a temperature of 40° C. and a relative humidity of 100% for one week compared to a reference composition containing a lower amount of silane groups of formula (I).

[0036] Preferably, at least a portion of the silane groups of formula (I) are bonded to at least one polymer P and / or the thermally expandable composition further comprises at least one alkoxysilane SI of formula (II)

[0037]

[0038] where R 1 and R 2 As defined above, and

[0039] R 3 represents a linear, branched or cyclic alkenyl group having 1 to 20 carbon atoms, preferably having 1 to 10 carbon atoms,

[0040] According to one or more embodiments, at least 15% by weight, preferably at least 35% by weight, more preferably at least 50% by weight, even more preferably at least 75% by weight, yet more preferably at least 95% by weight of the silane groups of formula (I) are bonded to at least one polymer P. According to one or more embodiments, all silane groups of formula (I) contained in the thermally expandable composition are bonded to at least one polymer P.

[0041] According to one or more embodiments, at least one alkoxysilane SI of formula (II) is chosen from vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris(2-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyldimethylmethoxysilane and vinylmethyldibutoxysilane, preferably from vinyltrimethoxysilane and vinyltriethoxysilane.

[0042] According to one or more embodiments, at least one polymer P is a silane-functionalized polymer containing silane groups of formula (I), preferably an organosilane-functionalized polymer containing silane groups of formula (I).

[0043] The term "organic polymer" in the present disclosure includes a collection of chemically homogeneous macromolecules that differ in degree of polymerization, molar mass and chain length, having a majority of carbon atoms in the polymer backbone, and the reaction products of such collections of macromolecules. Polymers having a polyorganosiloxane backbone (often referred to as "silicones") are not organic polymers in the context of the present disclosure.

[0044] Suitable silane-functionalized polymers to be used as at least one polymer P may contain polymerized or grafted silane functionality, ie the silane groups of formula (I) may be present as part of the polymer backbone or grafted onto the polymer as side chains.

[0045] According to one or more embodiments, at least one polymer P has been obtained by grafting an alkoxysilane of formula (II) onto the polymer chain of one or more polymers or by copolymerizing an alkoxysilane of formula (II) with one or more comonomers. Suitable comonomers for copolymerization with the alkoxysilane of formula (II) include, for example, ethylene, propylene, 1-butene and higher α-olefins, (meth)acrylates and (meth)acrylic acid. The term "(meth)acrylate" in the present disclosure refers to both acrylates and methacrylates.

[0046] According to one or more embodiments, at least one polymer P has been obtained by grafting one or more alkoxysilanes of formula (II) onto at least one starting polymer, for example by reacting one or more alkoxysilanes of formula (II), at least one starting polymer and one or more peroxides, wherein the at least one starting polymer is preferably selected from polyethylene, ethylene-α-olefin copolymers, polypropylene, propylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin (meth)acrylate alkyl ester copolymers and olefin (meth)acrylic acid copolymers.

[0047] The term "α-olefin" designates an olefin having the molecular formula C x H2 xAn olefin (x corresponds to the number of carbon atoms) characterized by a carbon-carbon double bond at the first carbon atom (the α-carbon). Examples of α-olefins include ethylene, propylene, 1-butene, 2-methyl-1-propene (isobutylene), 1-pentene, 1-hexene, 1-heptene, and 1-octene. For example, 1,3-butadiene or 2-butene or styrene are not referred to as "α-olefins" according to the present disclosure. The term "poly-α-olefin" designates homopolymers and copolymers obtained by polymerization or oligomerization of α-olefins or a plurality of different α-olefins.

[0048] According to one or more embodiments, at least one polymer P is selected from silane-grafted ethylene-vinyl acetate copolymers, silane-grafted polyolefins, olefin silane copolymers and olefin (meth)acrylate alkyl silane terpolymers, preferably from silane-grafted ethylene-vinyl acetate copolymers, olefin silane copolymers and olefin (meth)acrylate alkyl silane terpolymers, more preferably from silane-grafted ethylene-vinyl acetate copolymers and olefin (meth)acrylate alkyl silane terpolymers.

[0049] According to one or more embodiments, at least one polymer P comprises or consists of at least one silane-grafted ethylene-vinyl acetate copolymer, wherein the at least one silane-grafted ethylene-vinyl acetate copolymer is preferably obtained by reacting at least one ethylene-vinyl acetate copolymer with one or more alkoxysilanes of formula (II) and one or more organic peroxides. In general, the expression "at least one component X comprises at least one component N", for example "at least one polymer P comprises at least one silane-grafted ethylene-vinyl acetate copolymer" is understood in the context of the present disclosure to mean that the composition comprises one or more silane-grafted ethylene-vinyl acetate copolymers as a representative of the at least one polymer P.

[0050] According to one or more embodiments, the at least one polymer P comprises or consists of at least one silane-grafted ethylene-vinyl acetate copolymer, wherein the at least one silane-grafted ethylene-vinyl acetate copolymer is preferably obtained by reacting at least one ethylene-vinyl acetate copolymer with one or more alkoxysilanes of formula (II) and one or more organic peroxides.

[0051] According to one or more embodiments, the at least one polymer P comprises or consists of at least one olefin silane copolymer or olefin alkyl (meth)acrylate silane terpolymer, preferably consists of at least one olefin alkyl (meth)acrylate silane terpolymer.

[0052] According to one or more embodiments, the at least one polymer P comprises or consists of at least one first silane-grafted ethylene-vinyl acetate copolymer P1 and at least one second silane-grafted ethylene-vinyl acetate copolymer P2 different from the at least one first silane-grafted ethylene-vinyl acetate copolymer P1, wherein the at least one first silane-grafted polymer P1 is preferably obtained by reacting at least one first ethylene-vinyl acetate copolymer with one or more alkoxysilanes of formula (II) and one or more organic peroxides, and wherein the at least one second silane-grafted polymer P2 is preferably obtained by reacting at least one second ethylene-vinyl acetate copolymer different from the at least one first ethylene-vinyl acetate copolymer with one or more alkoxysilanes of formula (II) and one or more organic peroxides.

[0053] According to one or more embodiments, the weight ratio of the total amount of at least one first silane-grafted ethylene-vinyl acetate copolymer P1 and at least one second silane-grafted ethylene-vinyl acetate copolymer P2 is in the range of 5:1-1:3, preferably 3:1-1:2, more preferably 2.5:1-1:1.

[0054] According to one or more further embodiments, the thermally expandable composition further comprises at least one alkoxysilane SI of formula (II).

[0055] The thermally expandable composition also comprises at least one free radical initiator I. All types of free radical initiators known to undergo decomposition when exposed to a sufficient amount of energy, such as radiation, heat, etc., thereby generating free radicals capable of initiating the desired curing (crosslinking) reaction are in principle considered suitable for use as the at least one free radical initiator I.

[0056] According to one or more embodiments, the at least one free radical initiator I is a peroxide initiator PI, preferably an organic peroxide.

[0057] Suitable peroxide initiators are substantially inert at room temperature (23°C) and exhibit an activation temperature suitable for the intended purpose. For example, if the thermally expandable composition is to be used to provide fascia and / or reinforcement elements in automotive manufacturing, an activation temperature in the range of 90-250°C is generally preferred. Furthermore, it is advantageous if the at least one peroxide initiator PI has an activation temperature that is compatible with the decomposition temperature of the at least one chemical blowing agent CBA. If the two temperatures mentioned above differ too greatly, it may be difficult to obtain a thermally expandable composition with optimal performance and stability.

[0058] It may also be advantageous if the at least one peroxide initiator PI has a half-life of 10 h at a temperature in the range of 90-130°C, as measured in benzene or a similar non-polar solvent. For certain types of peroxide initiators, solvents other than benzene may be more suitable for measuring the half-life, such as toluene, triethyl phosphate, or dibutyl phthalate. For ultra-low temperature embodiments, i.e., those optimized for expansion between 120°C and 150°C, peroxide initiators having a half-life of 10 h at a temperature in the range of 50-100°C are preferred. It may also be advantageous if the at least one peroxide initiator PI is compatible and / or miscible with the polymer matrix of the thermally expandable composition. In some cases, the compatibility of the peroxide initiator with the polymer matrix can be further improved by using processing aids and other compatibilizing additives.

[0059] Suitable peroxide initiators include in particular organic peroxides. All types of organic peroxides which are known to undergo decomposition upon heating and thereby generate free radicals which are able to initiate the desired curing (crosslinking) reaction are in principle considered suitable for use as the at least one peroxide initiator PI.

[0060] According to one or more embodiments, at least one peroxide initiator PI is an organic peroxide, preferably selected from ketone peroxides, diacyl peroxides, peresters, perketals and hydroperoxides. Examples of preferred peroxides include cumene hydroperoxide, tert-butyl peroxide, bis(tert-butylperoxy)-diisopropylbenzene, di(tert-butylperoxyisopropyl)benzene, dicumyl peroxide, tert-butyl peroxybenzoate, dialkyl peroxydicarbonate, diperoxyketals (e.g., 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane), ketone peroxides (e.g., methyl ethyl ketone peroxide), and 4,4-di-tert-butylperoxy-n-butyl valerate.

[0061] Particularly preferred organic peroxides include 3,3,5,7,7-pentamethyl-1,2,4-tricyclooxaheptane, 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylcumyl peroxide, di(tert-butylperoxyisopropyl)benzene, dicumyl peroxide, butyl-4,4-di(tert-butylperoxy)valerate, tert-butylperoxy-2-ethylhexyl carbonate, 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane, tert-butyl peroxybenzoate, di(4-methylbenzoyl)peroxide, and dibenzoyl peroxide.

[0062] According to one or more embodiments, the at least one peroxide initiator PI is selected from dicumyl peroxide, and / or di(tert-butylperoxyisopropyl)benzene, and / or 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane.

[0063] These are for example trade names BC-40B-PD from Akzo Nobel and DC-40PK (dicumyl peroxide) from Pergan; 14-40B-PD from Akzo Nobel and BIB-40P (di(tert-butylperoxyisopropyl)benzene) from Pergan; and sold under the trade name PK295 (di(tert-butylperoxyisopropyl)benzene) is commercially available from Pergan.

[0064] According to one or more embodiments, the at least one peroxide initiator PI comprises 0.01-10.0 wt %, preferably 0.025-7.5 wt %, more preferably 0.05-5.0 wt %, even more preferably 0.1-3.5 wt %, still more preferably 0.15-3.5 wt %, most preferably 0.25-3.0 wt %, based on the total weight of the thermally expandable composition.

[0065] It may also be advantageous if the at least one peroxide initiator PI is present in the thermally expandable composition in the form of a carrier material such as silica, kaolin, and / or calcium carbonate, or other suitable material. This approach can facilitate the handling, dosage, and uniform distribution of the at least one peroxide initiator PI in the thermally expandable composition. Examples of fixed organic peroxides include, for example, 40% by weight of dicumyl peroxide on calcium carbonate, 40% by weight of di(tert-butylperoxyisopropyl)benzene on clay and silica, and 40% by weight of 1,1-di(tert-butylperoxy)-3,3,5-trimethylcyclohexane on calcium carbonate. In these embodiments, the expression "amount of the at least one peroxide initiator PI" refers to the amount of active substance contained in the thermally expandable composition, excluding the amount of the carrier material on which the at least one peroxide initiator PI, such as the organic peroxide, is fixed.

[0066] According to one or more embodiments, the at least one free radical initiator I is an azo initiator AI, preferably selected from azonitrile compounds, alkylazo compounds and azoamide compounds.

[0067] Suitable azo initiators are essentially inert at normal room temperature (23°C) and exhibit an activation temperature suitable for the intended purpose. For example, if the thermally expandable composition is used to provide fascia and / or reinforcement elements in automotive manufacturing, an activation temperature in the range of 90-250°C is generally preferred. Furthermore, it is advantageous for the at least one azo initiator AI to have an activation temperature that is compatible with the decomposition temperature of the at least one chemical blowing agent CBA. If the two temperatures mentioned above differ too greatly, it may be difficult to obtain a thermally expandable composition with optimal performance and stability.

[0068] It may also be advantageous if the at least one azo initiator AI has a half-life of 10 h at a temperature in the range of 55-120° C., as measured in toluene or a similar non-polar solvent. For certain types of azo initiators, solvents other than toluene may be more suitable for half-life measurements, such as substituted (e.g., chlorinated) benzenes, methanol, or water. The choice of a suitable solvent depends primarily on the solubility of the azo initiator in the respective solvent. It may also be advantageous if the at least one azo initiator AI is compatible and / or miscible with the polymer matrix of the thermally expandable composition. In some cases, the compatibility of the azo initiator with the polymer matrix may be further improved by the use of processing aids and other compatibilizing additives.

[0069] Suitable azo initiators to be used as the at least one azo initiator AI include, for example, 4,4′-azobis(4-cyanovaleric acid), 1,1′-azobis(cyclohexane-1-carbonitrile) (ACHN), azobisisobutyronitrile (AIBN), 2,2′-azobis(2-methylpropionamidine), 2,2′-azobis(2-methylpropionitrile), 4,4-azobis(di-tert-butyl 4-cyanoperoxyvalerate), 4,4-azobis(di-tert-butyl 4-cyanoperoxyhexanoate), 4,4-azobis(di-tert-butyl 4-cyanoperoxyheptanoate), 2,2 '-Azobis(dimethyl 2-methylpropionate), 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(N-butyl-2-methylpropionamide), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2-methylpropionamidine) dihydrochloride, 2,2'-azobis[N-(2-carboxyethyl)-2-methylpropionamidine] tetrahydrate, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0070] According to one or more embodiments, the at least one azo initiator AI is selected from azobisisobutyronitrile (AIBN), 1,1′-azobis(cyclohexane-1-carbonitrile) (ACHN), and 2,2′-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0071] According to one or more embodiments, the at least one azo initiator AI comprises 0.1-10.0 wt %, preferably 0.15-7.5 wt %, more preferably 0.25-5.0 wt %, even more preferably 0.25-3.5 wt %, still more preferably 0.35-3.5 wt %, most preferably 0.5-3.5 wt %, based on the total weight of the thermally expandable composition.

[0072] The thermally expandable composition further comprises at least one chemical blowing agent (CBA). A chemical blowing agent is an organic or inorganic compound that decomposes under the influence of, for example, temperature or humidity, forming at least one gaseous decomposition product. Commonly used chemical blowing agents include exothermic and endothermic chemical blowing agents, such as azo compounds, hydrazides, nitroso compounds, carbamates, carbohydrazides, bicarbonates, polycarboxylic acids, and salts of polycarboxylic acids.

[0073] Suitable exothermic chemical blowing agents for use as the at least one chemical blowing agent CBA include, for example, azodicarbonamide, azoisobutyronitrile, azocyclohexanecarbonitrile, dinitrosopentamethylenetetramine, azodiaminobenzene, benzene-1,3-sulfonylhydrazide, calcium azide, 4,4′-diphenyldisulfonyl azide, p-toluenesulfonylhydrazide, p-toluenesulfonylsemicarbazide, 4,4′-oxybis(benzenesulfonylhydrazide), trihydrazinotriazine and N,N′-dimethyl-N,N′-dinitrosoterephthalamide, and combinations thereof, and the like.

[0074] According to one or more embodiments, the at least one chemical blowing agent CBA comprises or consists of one or more selected from azodicarbonamide, dinitrosopentamethylenetetramine and 4,4′-oxybis(benzenesulfonylhydrazide), and most preferably azodicarbonamide.

[0075] Although exothermic chemical blowing agents are widely used in thermally expandable compositions, particularly in the automotive industry, it may be preferable to provide thermally expandable compositions that do not contain them. Exothermic blowing agents may not always be preferred, as they have been found to have the potential to trigger respiratory sensitization, are generally unsafe from a toxicological point of view, or present an explosion risk. Furthermore, during the decomposition of exothermic blowing agents, byproducts such as ammonia, formamide, formaldehyde, or nitrosamines are released, which are classified as hazardous substances and their use is prohibited in automotive manufacturing.

[0076] According to one or more additional embodiments, at least one chemical blowing agent (CBA) is an endothermic chemical blowing agent. Endothermic chemical blowing agents have the advantage that they are not hazardous or explosive and produce relatively few volatile organic compounds (VOCs) during their decomposition. The decomposition products are essentially carbon dioxide and water.

[0077] According to one or more embodiments, the at least one chemical blowing agent (CBA) is an endothermic chemical blowing agent comprising at least one organic acid. Suitable organic acids to be used in the endothermic chemical blowing agent include, for example, monocarboxylic acids such as acetic acid and propionic acid, and solid polycarboxylic acids such as solid, hydroxy-functionalized or unsaturated dicarboxylic acids, tricarboxylic acids, tetracarboxylic acids, or polycarboxylic acids, such as citric acid, tartaric acid, malic acid, fumaric acid, and maleic acid.

[0078] According to one or more embodiments, the at least one chemical blowing agent CBA comprises at least 85 wt.-%, preferably at least 90 wt.-%, more preferably at least 95 wt.-%, even more preferably at least 97.5 wt.-%, yet more preferably at least 99 wt.-% of at least one organic acid, based on the total weight of the at least one chemical blowing agent CBA.

[0079] According to one or more embodiments, the at least one organic acid is a polyfunctional organic acid having at least two acidic functional groups, preferably at least two carboxyl groups. Partially esterified polyfunctional organic acids having at least one free acidic functional group, in particular at least one free carboxyl group, are also suitable. According to one or more embodiments, the at least one organic acid has a molecular weight of no greater than 1000 g / mol, preferably no greater than 750 g / mol, and more preferably no greater than 500 g / mol.

[0080] According to one of the various embodiments, the at least one chemical blowing agent CBA comprises or consists of at least one organic acid chosen from citric acid, tartaric acid, malic acid, fumaric acid and maleic acid, preferably citric acid.

[0081] The at least one organic acid may be present in the thermally expandable composition in free acid form, i.e. with protonated acidic functional groups, or as a salt with deprotonated acidic functional groups, e.g. as a carboxylate, or as a mixture of these. Suitable cations for the carboxylate include, for example, Li + 、Na + , K + NH4 + , Ca2 + Mg2 + Etc. According to one or more embodiments, at least one organic acid is present in the thermally expandable composition in free acid form.

[0082] According to one or more embodiments, the at least one chemical blowing agent CBA has a maximum decomposition peak temperature measured by differential scanning calorimetry (DSC) in the range of 135-235° C., preferably 150-225° C., more preferably 155-200° C., even more preferably 160-200° C. Preferably, the maximum decomposition peak measured by DSC is determined by a DSC822e differential scanning calorimeter from Mettler-Toledo, by holding the sample at 25° C. for 2 min, then heating the sample from 25° C. to 280° C. at a rate of 5° C. / min, then holding the sample at 280° C. for 2 min, and finally cooling the sample from 280° C. to 25° C. at a rate of 10° C. / min.

[0083] The amount of the at least one chemical blowing agent CBA contained in the thermally expandable composition is not particularly limited, and the preferred amount depends on the desired expansion rate. According to one or more embodiments, the at least one chemical blowing agent CBA accounts for 1-20 weight %, preferably 2.5-15 weight %, more preferably 5-15 weight %, and even more preferably 5-10 weight % of the total weight of the thermally expandable composition.

[0084] According to one or more embodiments, the thermally expandable composition further comprises at least one epoxy-functional polymer EP.

[0085] Preferably, the at least one epoxy-functional polymer EP has an average of more than one epoxy group per molecule. Furthermore, the at least one epoxy-functional polymer EP may contain polymerized or grafted epoxy functionality, i.e., the epoxide moiety may be present as part of the polymer backbone or grafted onto the polymer as a side chain. Such epoxy-functional polymers may be added to thermally expandable compositions, for example, as adhesion promoters to improve adhesion of the expanded composition to oily surfaces, such as oily steel, as are commonly found, for example, in automotive manufacturing.

[0086] According to one or more embodiments, at least one epoxy-functional polymer EP is selected from olefin (meth)acrylate glycidyl copolymers, olefin (meth)acrylate alkyl ester (meth)acrylate glycidyl (meth)acrylate terpolymers and glycidyl methacrylate grafted (co)polymers. The term "(co)polymer" is understood to include homopolymers, copolymers, random copolymers, block copolymers and terpolymers.

[0087] Suitable olefin glycidyl (meth)acrylate copolymers to be used as the at least one epoxy-functional polymer EP include, for example, copolymers of ethylene, propylene or butylene with glycidyl acrylate (GA) or with glycidyl (meth)acrylate (GMA).

[0088] According to one or more embodiments, the at least one epoxy-functional polymer EP comprises at least one olefin glycidyl (meth)acrylate copolymer EP1, preferably selected from ethylene glycidyl (meth)acrylate copolymers, propylene glycidyl (meth)acrylate copolymers and butylene glycidyl (meth)acrylate copolymers, more preferably selected from ethylene glycidyl (meth)acrylate copolymers, in particular ethylene glycidyl methacrylate copolymers.

[0089] According to one or more embodiments, at least one olefin glycidyl (meth)acrylate copolymer EP1 has

[0090] - a glycidyl methacrylate content of 1 to 50% by weight, more preferably 2 to 25% by weight, and / or

[0091] - a melt flow index of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min, even more preferably not more than 25 g / 10 min, determined according to ISO 1133 (190° C. / 2.16 kg), and / or

[0092] - Melting temperature (T m ) is equal to or lower than 150°C, preferably equal to or lower than 135°C, in particular in the range of 75-150°C, preferably 85-135°C, more preferably 90-125°C.

[0093] According to one or more embodiments, the at least one epoxy-functional polymer EP is composed of at least one olefin (meth) acrylate glycidyl copolymer EP1, preferably selected from ethylene (meth) acrylate glycidyl copolymers, propylene (meth) acrylate glycidyl copolymers and butylene (meth) acrylate glycidyl copolymers, more preferably selected from ethylene (meth) acrylate glycidyl copolymers, in particular ethylene methacrylate glycidyl copolymers. Generally, the expression "at least one component X is composed of at least one component XN", for example "at least one epoxy-functional polymer EP is composed of at least one olefin (meth) acrylate glycidyl copolymer EP1" is understood to mean in the context of the present disclosure that the at least one epoxy-functional polymer EP is selected from at least one olefin (meth) acrylate glycidyl copolymer EP1.

[0094] Suitable olefin alkyl (meth)acrylate glycidyl (meth)acrylate terpolymers to be used as the at least one epoxy-functional polymer EP include, for example, terpolymers, in particular random terpolymers, of ethylene and an alkyl (meth)acrylate with glycidyl acrylate (GA) or with glycidyl methacrylate (GMA), wherein the alkyl group of the alkyl (meth)acrylate is preferably selected from methylene, ethylene, propylene and butylene, in particular methylene or butylene.

[0095] Preferred olefin alkyl (meth)acrylate glycidyl (meth)acrylate terpolymers include ethylene methyl acrylate glycidyl acrylate terpolymer (E / MA / GA), ethylene ethyl acrylate glycidyl acrylate terpolymer (E / EA / GA), ethylene propyl acrylate glycidyl acrylate terpolymer (E / PA / GA), ethylene butyl acrylate glycidyl acrylate terpolymer (E / BA / GA), ethylene methyl methacrylate glycidyl acrylate terpolymer (E / MMA / GA), ethylene ethyl methacrylate glycidyl acrylate terpolymer (E / EMA / GA), ethylene propyl methacrylate glycidyl acrylate terpolymer (E / PMA / GA), ethylene butyl methacrylate glycidyl acrylate terpolymer (E / BMA / GA), and ethylene methyl methacrylate glycidyl acrylate terpolymer (E / MMA / GA). GA), ethylene methyl acrylate glycidyl methacrylate terpolymer (E / MA / GMA), ethylene ethyl acrylate glycidyl methacrylate terpolymer (E / EA / GMA), ethylene propyl acrylate glycidyl methacrylate terpolymer (E / PA / GMA), ethylene butyl acrylate glycidyl methacrylate terpolymer (E / BA / GMA), ethylene methyl methacrylate glycidyl methacrylate terpolymer (E / MMA / GMA), ethylene methyl methacrylate ethyl glycidyl methacrylate terpolymer (E / EMA / GMA), ethylene propyl methacrylate glycidyl methacrylate terpolymer (E / PMA / GMA), ethylene butyl methacrylate glycidyl methacrylate terpolymer (E / BMA / GMA).

[0096] According to one or more embodiments, the at least one epoxy-functional polymer EP comprises at least one olefin alkyl acrylate glycidyl (meth)acrylate terpolymer EP2, preferably selected from random terpolymers of ethylene, alkyl (meth)acrylate and glycidyl methacrylate, wherein the alkyl group of the alkyl (meth)acrylate is preferably selected from methylene, ethylene, propylene and butylene, in particular methylene or butylene.

[0097] According to one or more embodiments, at least one olefin alkyl acrylate glycidyl (meth)acrylate terpolymer EP2 has

[0098] - a glycidyl methacrylate content of 1 to 50% by weight, more preferably 2 to 25% by weight, and / or

[0099] - a melt flow index of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min, determined according to ISO 1133 (190°C / 2.16 kg), and / or

[0100] - Melting temperature (T m ) is equal to or lower than 150°C, preferably equal to or lower than 135°C, in particular in the range of 75-150°C, preferably 85-135°C, more preferably 90-125°C.

[0101] According to one or more embodiments, the at least one epoxy-functional polymer EP consists of at least one olefin alkyl acrylate glycidyl (meth)acrylate terpolymer EP2, preferably chosen from random terpolymers of ethylene, alkyl (meth)acrylate and glycidyl methacrylate, wherein the alkyl group of the alkyl (meth)acrylate is preferably chosen from methylene, ethylene, propylene and butylene, in particular methylene or butylene.

[0102] Suitable glycidyl (meth)acrylate grafted (co)polymers to be used as the at least one epoxy-functional polymer EP include, for example, glycidyl methacrylate grafted olefin vinyl acetate copolymers, glycidyl methacrylate grafted ethylene-α-olefin copolymers, glycidyl methacrylate grafted propylene-α-olefin copolymers, glycidyl methacrylate grafted polyethylene, glycidyl methacrylate grafted polypropylene, and glycidyl methacrylate grafted olefin copolymer elastomers, glycidyl (meth)acrylate grafted styrene butadiene copolymers, and glycidyl (meth)acrylate grafted styrene ethylene butylene styrene terpolymers.

[0103] According to one or more embodiments, the at least one epoxy-functionalized polymer EP comprises at least one glycidyl methacrylate grafted (co)polymer EP3, preferably selected from glycidyl methacrylate grafted olefin vinyl acetate copolymers, glycidyl methacrylate grafted ethylene-α-olefin copolymers, glycidyl methacrylate grafted propylene-α-olefin copolymers, glycidyl methacrylate grafted polyethylene, glycidyl methacrylate grafted polypropylene, glycidyl (meth)acrylate grafted styrene butadiene copolymers, and glycidyl (meth)acrylate grafted styrene ethylene butylene styrene terpolymers.

[0104] According to one or more embodiments, at least one glycidyl methacrylate grafted (co)polymer EP3 has

[0105] - a content of glycidyl methacrylate (GMA) of 0.1 to 10% by weight, preferably 0.1 to 5% by weight, more preferably 0.1 to 3.5% by weight, even more preferably 0.1 to 2.5% by weight, in particular 0.1 to 1.5% by weight, and / or

[0106] - a melt flow index of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min, determined according to ISO 1133 (190°C / 2.16 kg), and / or

[0107] - Melting temperature (T m ) is equal to or lower than 150°C, preferably equal to or lower than 135°C, in particular in the range of 75-150°C, preferably 85-135°C, more preferably 90-125°C.

[0108] According to one or more embodiments, the at least one epoxy-functionalized polymer EP is composed of at least one glycidyl methacrylate grafted (co)polymer EP3, preferably selected from glycidyl methacrylate grafted olefin vinyl acetate copolymers, glycidyl methacrylate grafted ethylene-α-olefin copolymers, glycidyl methacrylate grafted propylene-α-olefin copolymers, glycidyl methacrylate grafted polyethylene, glycidyl methacrylate grafted polypropylene, glycidyl (meth)acrylate grafted styrene butadiene copolymers, and glycidyl (meth)acrylate grafted styrene ethylene butylene styrene terpolymers.

[0109] The at least one epoxy-functional polymer EP, if used, is preferably present in the thermally expandable composition in an amount of 0.5-35 wt. %, preferably 2.5-30 wt. %, more preferably 5-30 wt. %, even more preferably 10-25 wt. %, still more preferably 10-20 wt. %, based on the total weight of the thermally expandable composition.

[0110] According to one or more embodiments, the thermally expandable composition further comprises at least one activator A comprising at least one compound of formula (III)

[0111]

[0112] where R 4 and R 5independently of one another represent a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms, which furthermore optionally contain oxygen atoms, nitrogen atoms and / or aromatic moieties, or together form a divalent alkyl group having 1 to 10 carbon atoms, and which furthermore optionally contain oxygen atoms, nitrogen atoms and / or aromatic moieties;

[0113] R 6 and R 7 independently of one another represent a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms, which furthermore optionally contains oxygen atoms or nitrogen atoms; and

[0114] The value of the index n is 1 or 2.

[0115] Preferably, R 4 and R 5 independently of one another represent a hydrogen atom or a monovalent linear or branched alkyl group having 1 to 10, preferably 1 to 5, more preferably 1 to 4 carbon atoms, which together optionally represent a divalent alkyl group forming a ring structure with the adjacent nitrogen atom and / or R 6 and R 7 Independently of one another, they represent a hydrogen atom or a monovalent linear or branched alkyl group having 1 to 10, preferably 1 to 5, more preferably 1 to 4 carbon atoms, which optionally together represent a divalent alkyl group forming a ring structure with the adjacent nitrogen atom.

[0116] Preferred compounds of formula (III) to be used as at least one activating agent A include those wherein R 4 and R 5 Both represent hydrogen atoms and / or R 6 and R 7 Both represent ethyl or methyl, preferably methyl groups. Other preferred compounds of formula (III) include those wherein R 4 、R 5 、R 6 and R 7 All represent ethyl or methyl, preferably methyl, or wherein R 4 、R 5 and R 6 represents an ethyl group or a methyl group, preferably a methyl group and R 7 represents a hydrogen atom, or R 4 and R 7 Both represent hydrogen atoms and R 5 and R 6 Both represent those of ethyl or methyl, preferably methyl groups.

[0117] According to one or more embodiments, at least one activator A comprises or consists of one or more compounds selected from urea, p-chlorophenyl-N,N-dimethylurea (monuron), 3-phenyl-1,1-dimethylurea (fenuron), 3,4-dichlorophenyl-N,N-dimethylurea (diuron), N-methylurea, N,N-dimethylurea, N,N'-dimethylurea, N,N,N'-trimethylurea, N,N,N',N'-tetramethylurea and derivatives thereof, in which some or all of the methyl groups are replaced by ethyl groups.

[0118] Suitable urea activators are commercially available, for example under the trade name (from AlzChem Group AG), under the trade name (from CVC Thermoset Specialties) and sold under the trade name (From Evonik).

[0119] According to one or more preferred embodiments, the at least one activator A comprises or consists of a compound according to formula (III), wherein R 5 and R 6 Both represent hydrogen atoms and R 4 and R 7 Both represent methyl groups, and n has a value of 1, thus describing N,N-dimethylurea. This activator A is particularly suitable for use with chemical blowing agents CBA containing azodicarbonamide. This type of activator-blowing agent combination results in excellent expansion volume and highly stable foams throughout the entire temperature range of at least 140°C to 200°C, as well as expansion ratios of at least 1000%, preferably at least 1100%, at every temperature within this range.

[0120] According to one or more further preferred embodiments, the at least one activator A comprises or consists of a compound of formula (III), wherein R 4 、R 5 、R 6 and R 7 Both represent hydrogen atoms, thus describing urea. This activator A is particularly suitable for use with a chemical blowing agent CBA comprising 4,4′-oxybis(benzenesulfonylhydrazide). This type of activator-blowing agent combination results in an excellent expansion volume over the entire temperature range of at least 140°C to 200°C, and an expansion ratio of at least 1000%, preferably at least 1100%, at every temperature within this range.

[0121] If used, at least one activator A is preferably present in the thermally expandable composition in an amount of 1-10 wt%, more preferably 1-9 wt%, even more preferably 1.5-8 wt%, based on the total weight of the thermally expandable composition.

[0122] It is highly recommended to optimize the amount of the at least one activator A relative to the amount of the at least one chemical blowing agent CBA. For example, the at least one activator A may preferably be used in an amount of 10-80 wt. %, more preferably 12-65 wt. %, even more preferably 15-55 wt. %, yet more preferably 20-45 wt. %, based on the total weight of the at least one chemical blowing agent CBA contained in the thermally expandable composition.

[0123] It may also be advantageous if the heat-expandable composition contains at least one secondary activator SA in combination with at least one activator A. Examples of compounds suitable for use as the at least one secondary activator SA include, for example, zinc compounds such as zinc oxide, zinc acetate, zinc stearate, zinc bis(p-toluenesulfinate) or zinc bis(benzenesulfinate), titanium oxide and magnesium oxide, and fatty acids having at least 6 carbon atoms such as stearic acid and montanic acid. Preferred secondary activators are zinc compounds, especially zinc oxide, and mixtures of zinc compounds, especially mixtures of zinc oxide and zinc acetate and fatty acids having at least 6 carbon atoms. This type of secondary activator can be added to the heat-expandable composition in an amount of 1–10% by weight, preferably 1.25–7.5% by weight, and more preferably 1.4–5% by weight, based on the total weight of the heat-expandable composition.

[0124] It is also highly recommended to optimize the amount of the optional secondary activator relative to the amount of the at least one blowing agent CBA. For example, it may be preferred to use the at least one secondary activator SA in an amount of 10-80 wt. %, more preferably 12-65 wt. %, even more preferably 15-55 wt. %, and still more preferably 20-45 wt. %, based on the weight of the at least one chemical blowing agent CBA contained in the thermally expandable composition.

[0125] According to one or more embodiments, the thermally expandable composition comprises at least one secondary activator SA selected from zinc oxide, zinc acetate, zinc stearate, zinc bis(p-toluenesulfinate), zinc bis(benzenesulfinate) and fatty acids having at least 6 carbon atoms.

[0126] According to one or more embodiments, the thermally expandable composition comprises at least one first secondary activator SA1 selected from zinc oxide, zinc acetate, zinc stearate, zinc bis(p-toluenesulfinate), zinc bis(benzenesulfinate), preferably zinc oxide, and at least one second secondary activator SA2 selected from fatty acids having at least 6 carbon atoms, preferably stearic acid.

[0127] According to one or more embodiments, the thermally expandable composition further comprises at least one auxiliary agent CA comprising at least one multifunctional acrylate having an acrylate functionality of at least 2, preferably 2-6 and preferably having a molecular weight of less than 2500 g / mol, more preferably less than 1000 g / mol.

[0128] Such multifunctional acrylates can improve the crosslinking of the polymer components contained in the thermally expandable composition and help obtain a stable foam structure. The at least one auxiliary agent CA, if used, is preferably present in the thermally expandable composition in an amount of 0.05-5.0 wt. %, more preferably 0.1-3.5 wt. %, even more preferably 0.25-3.0 wt. %, still more preferably 0.35-2.0 wt. %, based on the total weight of the thermally expandable composition.

[0129] Suitable multifunctional acrylates with a functionality of 2 to be used as the at least one auxiliary agent CA include, for example, 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-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, and polybutylene glycol dimethacrylate, and hexanediol diacrylate. The most preferred acrylate with a functionality of 2 is hexanediol diacrylate.

[0130] Suitable polyfunctional acrylates with a functionality of 3 or more to be used as the at least one auxiliary CA include, for example, glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetraacrylate, di(trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris(2-methacryloyloxyethyl) trimellitate, tris(2-acryloyloxyethyl) isocyanurate, and ethoxylated or propoxylated derivatives thereof. The most preferred polyfunctional acrylate with a functionality of 5 is dipentaerythritol pentaacrylate. Also suitable are highly functional, hyperbranched acrylates with a functionality of 6 to 16 or more. Examples of such acrylates include hyperbranched polyester-polyacrylates.

[0131] According to one or more embodiments, the sum of the amounts of the at least one free radical initiator I and the at least one auxiliary agent CA (if present in the thermally expandable composition) is 0.25-7.5 wt. %, preferably 0.25-5.0 wt. %, more preferably 0.5-3.5 wt. %, even more preferably 0.75-2.5 wt. %, based on the total weight of the thermally expandable composition.

[0132] According to one or more embodiments, the thermally expandable composition further comprises at least one thermoplastic polymer TP.

[0133] In principle, all thermoplastic polymers and thermoplastic elastomers (TPE) are suitable as the at least one thermoplastic polymer TP. It goes without saying that the at least one thermoplastic polymer TP is different from the at least one polymer P and from the at least one epoxy-functional polymer EP.

[0134] Suitable polymers to be used as the at least one thermoplastic polymer TP include, for example, styrene-butadiene copolymers, styrene-isoprene copolymers, ethylene-vinyl acetate copolymers (EVA), olefin (meth)acrylate copolymers, olefin (meth)acrylate alkyl ester copolymers, olefin (meth)acrylic acid copolymers, polyolefins, and halogenated polyolefins such as polyvinyl chloride (PVC). Particularly suitable olefin (meth)acrylate copolymers and olefin (meth)acrylate alkyl ester copolymers include, for example, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers (EBA), and ethylene-2-ethylhexyl acrylate copolymers.

[0135] Suitable thermoplastic polymers TP may contain unsaturated olefinic bonds, and they may also contain functional groups in addition to the epoxy group, such as halogen, nitrile, mercaptan, hydroxyl or carboxyl groups. However, it is preferred that at least one thermoplastic polymer TP does not contain functional groups that interfere with the curing mechanism of the heat-expandable composition. This approach provides better controllability of the curing mechanism and secondary properties such as adhesion properties.

[0136] According to one or more embodiments, at least one thermoplastic polymer TP is a non-functionalized thermoplastic polymer, preferably selected from polyethylene, ethylene-α-olefin copolymers, polypropylene, propylene-α-olefin copolymers, ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin (meth)acrylate alkyl ester copolymers and olefin (meth)acrylic acid copolymers, more preferably selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers and olefin (meth)acrylate alkyl ester copolymers.

[0137] According to one or more embodiments, at least one thermoplastic polymer TP has

[0138] - a melt flow index of not more than 250 g / 10 min, preferably not more than 200 g / 10 min, even more preferably not more than 175 g / 10 min, determined according to ISO 1133 (190° C. / 2.16 kg), and / or

[0139] - Melting temperature (Tm ) is equal to or lower than 150°C, preferably equal to or lower than 125°C, more preferably equal to or lower than 100°C.

[0140] According to one or more embodiments, the at least one thermoplastic polymer TP comprises at least one first non-functionalized thermoplastic polymer TP1 and at least one second non-functionalized thermoplastic polymer TP2 different from the at least one first non-functionalized thermoplastic polymer TP1, wherein the at least one first and second non-functionalized thermoplastic polymers TP1 and TP2 are preferably selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin (meth)acrylate alkyl ester copolymers and olefin (meth)acrylic acid copolymers, more preferably selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers and olefin (meth)acrylate alkyl ester copolymers.

[0141] According to one or more embodiments, at least one first non-functionalized thermoplastic polymer TP1 has a melt flow index measured according to ISO 1133 (190°C / 2.16 kg) of at least 15 g / 10 min, more preferably at least 20 g / 10 min, even more preferably at least 25 g / 10 min, in particular 25-200 g / 10 min, preferably 30-175 g / 10 min and / or at least one second non-functionalized thermoplastic polymer TP2 has a melt flow index measured according to ISO 1133 (190°C / 2.16 kg) of not more than 25 g / 10 min, more preferably not more than 15 g / 10 min, even more preferably not more than 10 min, in particular 1-10 g / 10 min, preferably 1-7.5 g / 10 min.

[0142] According to one or more embodiments, the weight ratio of the amount of at least one first non-functionalized thermoplastic polymer TP1 to at least one second non-functionalized thermoplastic polymer TP2 is in the range of 5:1-1:3, preferably 3:1-1:2, more preferably 2.5:1-1:1.

[0143] According to one or more embodiments, the at least one thermoplastic polymer TP consists of at least one first non-functionalized thermoplastic polymer TP1 and at least one second non-functionalized thermoplastic polymer TP2, wherein the at least one first and second non-functionalized thermoplastic polymers TP1 and TP2 are preferably selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin (meth)acrylate alkyl ester copolymers and olefin (meth)acrylic acid copolymers, more preferably selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers and olefin (meth)acrylate alkyl ester copolymers.

[0144] According to one or more embodiments, the sum of the amounts of the at least one polymer P and the at least one thermoplastic polymer TP is 25-80 wt.-%, preferably 30-75 wt.-%, more preferably 35-70 wt.-%, even more preferably 40-65 wt.-%, still more preferably 40-60 wt.-%, based on the total weight of the thermally expandable composition.

[0145] In addition to the essential and optional ingredients listed above, the heat expandable composition may contain other compounds commonly used in such compositions and known to those skilled in the art. These include, for example, tackifying resins, fillers, colorants, dispersing aids or leveling agents, stabilizers, and the like.

[0146] The term "tackifying resin" in this document refers to a resin that generally enhances the adhesiveness and / or tack of a composition. The term "tack" in this document refers to the property of a substance to be sticky or adhesive upon simple contact, which can be measured, for example, as loop tack. Preferred tackifying resins enhance tack at a temperature of 25°C. Such tackifying resins result in good adhesion to metal substrates, particularly oiled metal substrates, both before and after foaming of the thermally expandable composition.

[0147] Suitable tackifying resins to be used in thermally expandable compositions have a relatively low average molecular weight (M n ), for example not more than 5000 g / mol, in particular not more than 3500 g / mol, preferably not more than 2500 g / mol and a softening point, determined by the ring and ball method in accordance with DIN EN 1238, of 180° C. or less, preferably 160° C. or less, more preferably 150° C. or less. Suitable tackifying resins include, in particular, synthetic resins, natural resins and chemically modified natural resins.

[0148] The term "synthetic resin" in the present disclosure refers to a compound obtained by a controlled chemical reaction, such as polyaddition or polycondensation between well-defined reactants that do not themselves have resin properties. Monomers that can be polymerized to synthesize synthetic resins can include aliphatic monomers, alicyclic monomers, aromatic monomers, or mixtures thereof. Suitable aliphatic monomers can include C4, C5, and C6 alkanes, olefins, and conjugated dienes. Examples of aliphatic monomers or alicyclic monomers include butadiene, isobutylene, 1,3-pentadiene, 1,4-pentadiene, cyclopentane, 1-pentene, 2-pentene, 2-methyl-1-pentene, 2-methyl-2-butene, 2-methyl-2-pentene, isoprene, cyclohexane, 1-3-hexadiene, 1-4-hexadiene, cyclopentadiene, and dicyclopentadiene. Examples of aromatic monomers include C8, C9, and C 10 Aromatic Monomers. Typical aromatic monomers include styrene, alpha-methylstyrene, vinyltoluene, methoxystyrene, tert-butylstyrene, chlorostyrene, benzofurans, and indene monomers, including indene and methylindene, and combinations thereof.

[0149] Suitable synthetic resins include, for example, hydrocarbon resins, coumarone-indene resins, polyindene resins, polystyrene resins, vinyltoluene-α-methylstyrene copolymer resins, and α-methylstyrene resins.

[0150] The term "hydrocarbon resin" as used in this disclosure refers to a synthetic resin made by polymerizing a mixture of unsaturated monomers obtained from petroleum-based feedstocks (e.g., byproducts of cracking of natural gas liquids, gas oils, or petroleum naphthas). These types of hydrocarbon resins are also known as "petroleum resins" or "petroleum hydrocarbon resins." Hydrocarbon resins also include pure monomer aromatic resins, which are prepared by polymerizing an aromatic monomer feedstock that has been purified to eliminate color-causing contaminants and precisely control the composition of the product.

[0151] Suitable hydrocarbon resins are available, for example, under the trade name Plus, Extra and STS (all from Cray Valley); under the trade name 1000 series, 2000 series and 5000 series (all from ExxonMobil Chemical); under the trade name T series, TT series, TD series, TL series, TN series, TK series and TV series (all from Novares GmbH); and under the trade name and (all from Eastman Chemicals) are commercially available.

[0152] If used, the tackifying resin is preferably included in the thermally expandable composition in an amount of 2-25 wt%, preferably 4-20 wt%, more preferably 5-15 wt%, based on the total weight of the thermally expandable composition.

[0153] Suitable filler to be used in heat-expandable composition comprises calcium carbonate, lime, calcium carbonate-magnesium carbonate, talcum, gypsum, graphite, barite, pyrolysis or precipitated silica, silicate, mica, wollastonite, kaolin, feldspar, chlorite, bentonite, montmorillonite, dolomite, quartz, cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic ball, hollow glass ball, hollow organic ball, glass ball, functionalized aluminoxane and carbon black that for example grind or precipitate.Suitable filler is included in the organic coating of the filler included in the tabulation presented above and uncoated commercially available form.Especially suitable filler comprises calcium carbonate, calcium carbonate-magnesium carbonate, talcum, gypsum, graphite, barite, pyrolysis or precipitated silica, silicate, mica, wollastonite, carbon black and their mixture that grind or precipitate.

[0154] If used, fillers are preferably included in the thermally expandable composition in an amount of 1-20 wt%, more preferably 1-15 wt%, even more preferably 2.5-15 wt%, based on the total weight of the thermally expandable composition.

[0155] Colorants or dyes such as pigments, for example based on carbon black, may also be included in the thermally expandable composition. Their amount is preferably between 0.1 and 1 wt. %, based on the total weight of the thermally expandable composition.

[0156] Preferably, the thermally expandable composition after curing has a volume increase of at least 100%, preferably at least 150%, more preferably at least 250% compared to the uncured composition, wherein the volume increase is determined using the DIN EN ISO 1183 method of density measurement (Archimedes' principle) in deionized water together with determination of the sample mass by a precision balance.

[0157] According to one or more embodiments, the thermally expandable composition after curing has a volume increase in the range of 100-3000%, preferably 150-2500%, more preferably 250-2000%, even more preferably 250-2000% compared to the uncured composition.

[0158] The heat expandable composition according to the invention can be produced by mixing the ingredients in any suitable mixing device, for example in a dispersing mixer, a planetary mixer such as a planetary roll, an extruder such as a twin-screw extruder, a kneader such as a Buss, Banbury or roll kneader, or a two-roll mill.

[0159] It may be advantageous to heat the ingredients before or during mixing, either by applying an external heat source or by friction generated by the mixing process itself, in order to facilitate processing of the components into a homogeneously mixed mixture by reducing the viscosity and / or melting the individual components. However, care must be taken, for example by temperature monitoring and the use of cooling devices (if appropriate), not to exceed the activation temperature of the at least one chemical blowing agent CBA and the at least one free radical initiator I. The thermally expandable composition thus obtained is preferably substantially solid at normal room temperature (23° C.), meaning that at this temperature, it does not significantly deform under gravity alone for at least 24 hours.

[0160] After the ingredients of the thermally expandable composition have been mixed, the composition thus obtained can be shaped into its desired form by, for example, extrusion, blow molding, pelletizing, injection molding, compression molding, blanking or stamping or using any other suitable method.

[0161] Can produce heat-expandable composition of the present invention in one-step method basically, comprise sequentially and / or add all compositions simultaneously.Yet, can also advantageously provide heat-expandable composition as two-part system or even multi-part system.In these cases, the composition of heat-expandable composition is provided in the compartment of independent air and moisture impermeable packaging or single packaging, and before the use time of heat-expandable composition or the use time, the composition of heat-expandable composition is mixed with each other and optionally mixed with other compounds immediately.Can for example adopt such scheme to improve the shelf life of heat-expandable composition in the place with harsh conditions (for example very high temperature), need and transport weight to optimize storage space, or to realize the modular composition of the customization that is provided for different applications.

[0162] The heat-expandable composition according to the invention is storage-stable under normal storage conditions. The term "storage-stable" in the present disclosure refers to a material that can be stored under specified storage conditions for a long period of time, for example at least one month, in particular at least three months, without any significant change in the application-relevant properties of the material. "Typical storage conditions" here refers to a temperature not higher than 60°C, in particular not higher than 50°C.

[0163] The expansion of the heat-expandable composition of the present invention is triggered by heating. This means that the heat-expandable composition is activated by a heating step above its activation temperature and for a sufficiently long duration to allow the at least one chemical blowing agent CBA to decompose (resulting in gas formation) until the expandable material expands and solidifies to its desired final (fully expanded and stable) state. The optimal temperature and duration (residence time) of the heating step depend on the embodiment of the heat-expandable composition, in particular the composition of the at least one chemical blowing agent CBA and the at least one free radical initiator I contained in the heat-expandable composition. The heat-expandable composition can have an activation temperature in the range of 120-250°C, preferably 140-220°C, and a residence time in the heating step in the range of 5-90 minutes, preferably 10-60 minutes.

[0164] The preferences given above for the at least one polymer P, the at least one epoxy-functional polymer EP, the at least one thermoplastic polymer TP, the at least one chemical blowing agent CBA, the at least one free-radical initiator I, the at least one activator A and the at least one auxiliary CA apply equally to all subjects of the present invention, unless otherwise stated.

[0165] Another subject of the present invention is a baffle and / or reinforcement element for a hollow structure comprising or essentially consisting of the thermally expandable composition according to the invention.

[0166] Such elements are used to seal, block and / or reinforce hollow structures, such as cavities in hollow structural parts of automobiles. Hollow parts in automobiles may include body parts (e.g., panels), frame parts (e.g., hydroformed tubes), pillar structures (e.g., A, B, C, or D pillars), bumpers, roofs, etc.

[0167] According to one or more embodiments, the baffle and / or reinforcement element for the hollow structure consists essentially of the thermally expandable composition of the present invention. In these embodiments, it is advantageous to provide the element with a shape such that it can be easily assembled and connected to the wall of the hollow structure to be blocked and / or reinforced. Such shaped elements can be provided from the thermally expandable composition, for example, by injection molding, blanking or stamping, or by extrusion through a shaped template.

[0168] According to one or more additional embodiments, the baffle and / or reinforcing element further comprises a carrier onto which the thermally expandable composition is deposited or attached. Such a design can be more cost-effective and can facilitate securing the baffle and / or reinforcing element to the wall of the structure to be blocked and / or reinforced, for example by incorporating pins, bolts, or hooks into the carrier element. Furthermore, using a suitable design of the carrier element can improve the mechanical properties and stability of the baffle and / or reinforcing element.

[0169] If used, the support for the baffle and / or reinforcement element can be composed of any material that can be processed into a certain shape. Preferred support materials include polymeric materials, such as plastics, elastomers, thermoplastics, blends thereof, and the like. Preferred thermoplastic materials include, but are not limited to, polymers such as polyurethanes, polyamides, polyesters, polyolefins, polysulfones, polyethylene terephthalate (PET), polyvinyl chloride (PVC), chlorinated polyolefins, and the like. Particularly preferred are high-temperature stable polymers such as polyphenylene ether, polysulfones, polyethersulfones, polyamides, particularly polyamide 6, polyamide 6,6, polyamide 11, polyamide 12, and mixtures thereof. Other suitable support materials include metals, especially aluminum or steel, or naturally occurring organic materials such as wood or other (pressed) fibrous materials. Glassy or ceramic materials may also be used. Any combination of such materials may also be used. It is also contemplated that such materials may be filled or foamed, for example, with fibers, minerals, clays, silicates, carbonates, combinations thereof, and the like.

[0170] The carrier element can also exhibit any shape or geometry. It can also consist of several parts that are not directly connected. For example, it can be solid, hollow, or foamed, or it can exhibit a grid-like structure. Depending on the intended use of the baffle and / or reinforcing element, the surface of the carrier element can generally be smooth, rough, or structured.

[0171] The present invention further provides a method for producing the baffle and / or reinforcing element according to the invention, wherein the thermally expandable composition is injection-molded onto a carrier or co-extruded with a carrier.

[0172] The details of the method for producing the baffle and / or reinforcing element of the invention depend primarily on the material of the carrier. If the material of the carrier can be (injection) molded or extruded, the baffle and / or reinforcing element can be produced in a two-step injection molding process or by coextrusion of the carrier and the thermally expandable composition.

[0173] In the case of a two-step injection molding process, the first step comprises injecting the material of the carrier into the mold. After solidification, the cavity of the injection molding tool is expanded or adjusted or the injection molded part is transferred to another tool, followed by a second step comprising injecting the thermally expandable composition.

[0174] If carrier can not be by injection molding or extrusion molding, for example because it is made up of metal or alloy, then carrier can be at first manufactured by suitable method and then introduced injection molding tool.Then can be placed in the instrument of carrier before heat expandable composition injection molding to.In addition heat expandable composition can be extruded on prefabricated carrier element.Certainly can also use any suitable method to manufacture the element of carrier and heat expandable composition separately, and then use any suitable means for example chemically or physically, for example by gluing etc., or mechanically for example by bolt, screw thread etc. the element of heat expandable composition is connected with carrier.

[0175] The present invention further provides for the use of at least one compound having silane groups of the formula (I) for improving the moisture storage resistance of a heat expandable material comprising components a) to c) and optionally d) of the heat expandable composition of the invention.

[0176] The expression "use of at least one compound for improving the storage resistance of a thermally expandable material to humidity" is understood to mean that the loss of expansion of the thermally expandable composition resulting from storage under humid conditions at elevated temperature is reduced due to the addition of at least one compound to the thermally expandable material.

[0177] According to one or more embodiments, at least one compound having a silane group of formula (I) is selected from silane-functionalized polymers containing a silane group of formula (I) and an alkoxysilane of formula (II), wherein the silane-functionalized polymer containing a silane group of formula (I) is preferably selected from silane-grafted ethylene-vinyl acetate copolymers, olefin silane copolymers and olefin (meth)acrylate alkyl silane terpolymers.

[0178] According to one or more embodiments, at least one compound containing silane groups of formula (I) is added to the thermally expandable material in such an amount that the thermally expandable material contains 0.05-10.0 wt. %, preferably 0.15-7.5 wt. %, more preferably 0.20-5.0 wt. %, even more preferably 0.25-3.5 wt. % of silane groups of formula (I), based on the total weight of the thermally expandable material.

[0179] Another subject matter of the present invention is the use of the baffles and / or reinforcing elements according to the invention for sealing, blocking or reinforcing cavities or hollow structures of land, water or air vehicles, preferably automotive vehicles and / or cavities of buildings, so as to reduce the transmission of noise, vibrations, moisture and / or heat and / or mechanically strengthen the structure surrounding the cavity or hollow structure.

[0180] A further subject of the present invention is a method for sealing, blocking and / or reinforcing a cavity or a hollow structure, wherein an element comprising the heat-expandable composition according to the invention is introduced into the cavity or hollow structure and subsequently expanded by subjecting it to heat and / or UV treatment, so that the cavity or hollow structure is at least partially filled with the expanded composition.

[0181] The temperature of the heat expansion step is preferably 140-250° C., more preferably 150-220° C., even more preferably 150-200° C. The preferred duration of the heat expansion step, ie the preferred baking time of the heat expandable composition, is 5-90 min, more preferably 10-60 min, even more preferably 10-30 min.

[0182] With regard to thermal activation of elements comprising a thermally expandable composition when used in the manufacture of automotive vehicles, it is advantageous to combine the thermal activation with a further process step comprising a heat treatment. An example of such a process step is electrophoretic coating (cathodic dip coating / coating) of the chassis of a vehicle body. Example

[0183] The following chemicals shown in Table 1 were used in formulating the thermally expandable composition.

[0184] Table 1

[0185]

[0186] * The calorimetric analysis was performed using a DSC822e differential scanning calorimeter from Mettler-Toledo by holding the sample at 25°C for 2 min, then heating the sample from 25°C to 280°C at a rate of 5°C / min, then holding the sample at 280°C for 2 min, and finally cooling the sample from 280°C to 25°C at a rate of 10°C / min.

[0187] Preparation of thermally expandable compositions

[0188] Use Brabender mixer with temperature control to prepare the heat-expandable composition comprising the components shown in Tables 3 and 4. In the preparation method, the polymer components are first mixed at a temperature of 110-115°C until a uniformly mixed mixture is obtained. The system is then cooled to a temperature below the activation (80-90°C) of the thermoreactive raw materials. The thermoreactive raw materials (free radical initiator, blowing agent) are then mixed into the system until a uniformly mixed mixture is obtained. The material thus obtained is subsequently hot-pressed into a test sample for volume expansion testing.

[0189] In the case of reference composition Ref-2 and exemplary compositions Ex-1 to Ex-5, premixes 1 to 6 containing the ingredients shown in Table 2 were used in the preparation of the thermally expandable compositions. The premixes were prepared using the following procedure. Polymers TP1 and TP2 were first mixed at a temperature of 100°C for 3 minutes using a Brabender mixer. Alkoxysilane SI and / or free radical initiator I1 (organic peroxide) were then added and mixing was carried out at the same temperature for 10 minutes. In the final step, the temperature was raised to 160°C and mixing was continued for another 15 minutes. The premixes used in the preparation of exemplary compositions Ex-1 to Ex-5 are believed to contain a mixture of two different silane-grafted ethylene-vinyl acetate copolymers.

[0190] Volume expansion and expansion loss after moisture storage

[0191] The expansion properties of the reference and exemplary compositions were tested by heat treating (baking) the prepared test samples in an oven at temperatures of 140°C and 200°C for 10 minutes. The heating ramp from room temperature (23°C) to the respective baking temperatures was 20 minutes (to 140°C and 200°C). Tables 3 and 4 show the temperature and the degree of expansion (in % based on the original volume before expansion) at the corresponding baking temperatures.

[0192] The volume expansion is determined by measuring the density of the test specimen before and after expansion. The density is determined according to DIN EN ISO 1183 using the immersion method (Archimedes' principle) in deionized water and measuring the mass with a precision balance.

[0193] The expansion properties were tested before ("initial") and after the moisture storage treatment. In the moisture storage treatment, the samples were stored at a relative humidity of 100% and a temperature of 40°C for a period of 7 days before baking. The "expansion loss" (in %) describing the moisture resistance of the tested heat-expandable compositions was calculated as

[0194]

[0195] Among them, Exp i is the initial expansion obtained using the test composition before the moisture storage treatment, whereas Exp h It is the expansion obtained after storage treatment in moisture.

[0196] Table 2

[0197] Composition, weight % Premix 1 Premix 2 Premix 3 Premix 4 Premix 5 Premix 6 Polymer TP1 64.87 64.04 64.55 63.91 62.98 61.79 Polymer TP2 34.93 34.48 34.76 34.41 33.91 33.27 Alkoxysilane SI - 1.48 0.50 1.47 2.91 4.75 Initiator I1 0.20 - 0.20 0.20 0.19 0.19 total 100.00 100.00 100.00 100.00 100.00 100.00

[0198] Table 3

[0199]

[0200]

[0201] Table 4

[0202]

[0203]

Claims

1. A baffle and / or reinforcement element for a hollow structure, comprising a thermally expandable composition comprising: a) at least one polymer P, b) at least one free radical initiator I, and c) at least one chemical blowing agent CBA, and d) at least one epoxy-functional polymer EP selected from olefin glycidyl (meth)acrylate copolymers, olefin alkyl acrylate glycidyl (meth)acrylate terpolymers and glycidyl (meth)acrylate grafted copolymers; Wherein the composition comprises a silane group of formula (I) where R 1 represents an alkyl group having 1 to 8 carbon atoms, R 2 represents an alkyl group having 1 to 8 carbon atoms, and the value of the index a is 0, 1, or 2; and At least some of the silane groups of the formula (I) are bonded to at least one polymer P.

2. The baffle and / or reinforcing element according to claim 1, wherein R 1 represents an alkyl group having 1 to 5 carbon atoms.

3. The baffle and / or reinforcing element according to claim 1, wherein R 2 represents an alkyl group having 1 to 5 carbon atoms. 4 . The baffle and / or reinforcing element according to claim 1 , wherein the index a has a value of 0 or 1.

5. The baffle and / or reinforcing element according to claim 1, wherein the thermally expandable composition comprises 0.05 to 10.0 wt% of silane groups of formula (I), based on the total weight of the thermally expandable composition.

6. The baffle and / or reinforcing element according to claim 1, wherein the thermally expandable composition comprises 0.15 to 7.5 wt. % of silane groups of formula (I), based on the total weight of the thermally expandable composition.

7. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein the composition further comprises at least one alkoxysilane SI of formula (II) where R 1 and R 2 As defined in any one of claims 1 to 6, and R 3 represents a linear, branched or cyclic alkenyl group having 1 to 20 carbon atoms.

8. The baffle and / or reinforcing element according to claim 7, wherein R 3 represents a linear, branched or cyclic alkenyl group having 1 to 10 carbon atoms.

9. The baffle and / or reinforcing element according to claim 7, wherein the at least one alkoxysilane SI of formula (II) is selected from vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris(2-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyldimethylmethoxysilane and vinylmethyldibutoxysilane.

10. The baffle and / or reinforcing element according to claim 7, wherein the at least one alkoxysilane SI of formula (II) is selected from vinyltrimethoxysilane and vinyltriethoxysilane.

11. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein at least one polymer P is a silane-functionalized polymer containing silane groups of formula (I).

12. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein at least one polymer P is an organosilane-functionalized polymer containing silane groups of formula (I).

13. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein at least one polymer P is selected from the group consisting of silane-grafted ethylene-vinyl acetate copolymers, olefin silane copolymers and olefin alkyl (meth)acrylate silane terpolymers.

14. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein the at least one free radical initiator I is a peroxide initiator PI.

15. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein at least one free radical initiator I is an organic peroxide.

16. The baffle and / or reinforcing element according to claim 1, wherein the at least one epoxy-functional polymer (EP) represents 5-30% by weight of the total weight of the thermally expandable composition.

17. The baffle and / or reinforcing element according to claim 1, wherein the at least one epoxy-functional polymer (EP) represents 10-25 wt. % of the total weight of the thermally expandable composition.

18. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein the thermally expandable composition further comprises at least one activator A comprising at least one compound of formula (III) where R 4 and R 5 independently of one another represent a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms, which furthermore optionally contain oxygen atoms, nitrogen atoms and / or aromatic moieties, or together form a divalent alkyl group having 1 to 10 carbon atoms, and which furthermore optionally contain oxygen atoms, nitrogen atoms or aromatic moieties; R 6 and R 7 independently of one another represent a hydrogen atom or a monovalent alkyl group having 1 to 10 carbon atoms, which furthermore optionally contains oxygen atoms or nitrogen atoms; and The value of the index n is 1 or 2.

19. The baffle and / or reinforcing element according to any one of claims 1 to 6, wherein the thermally expandable composition further comprises at least one auxiliary agent CA comprising at least one multifunctional acrylate having an acrylate functionality of at least 2.

20. The baffle and / or reinforcing element according to claim 19, wherein the multifunctional acrylate has an acrylate functionality of 2 to 6.

21. The baffle and / or reinforcing element according to claim 19, wherein the multifunctional acrylate has a molecular weight of less than 2500 g / mol.

22. The baffle and / or reinforcing element of claim 19, wherein the multifunctional acrylate has a molecular weight of less than 1000 g / mol.

23. Use of at least one compound having a silane group of formula (I) as defined in claim 1 for improving the moisture storage resistance of a thermally expandable material comprising components a) to d) of a thermally expandable composition as defined in any one of the preceding claims.

24. The baffle and / or reinforcing member according to claim 1, further comprising a carrier on which the thermally expandable composition is deposited or attached.

25. The method for producing a baffle and / or a reinforcing element according to claim 24, wherein the thermally expandable composition is injection molded onto the carrier or coextruded together with the carrier.

26. Use of baffles and / or reinforcing elements according to any one of claims 1-22 or 24 for sealing, blocking or reinforcing cavities or hollow structures of land, water or air vehicles and / or cavities of buildings, so as to reduce the transmission of noise, vibrations, moisture and / or heat and / or mechanically strengthen the structure surrounding the cavity.

27. The use according to claim 26, wherein the vehicle is an automotive vehicle.

28. Method for sealing, blocking and / or reinforcing a cavity or a hollow structure, wherein an element comprising a heat-expandable composition according to any one of claims 1 to 22 is introduced into the cavity or hollow structure and subsequently expanded by heat, so that the cavity or hollow structure is at least partially filled with the expanded composition.

Images