Heating-expandable composition having improved wet storage resistance

Abstract

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

Description

Technical Field

[0001] The present invention relates to heat-expandable compositions and their use for providing shielding elements (baffles) and / or reinforcing elements. Such components are particularly suitable for use in sealing, shielding and / or reinforcing cavities in hollow structures, such as hollow structural parts of motor vehicles.

Background Art

[0002] Manufactured articles often contain orifices, cavities or other hollow parts that result from the manufacturing process and / or are designed into the product for various purposes, such as weight reduction. Motor vehicles, for example, contain several such orifices and cavities throughout the vehicle, such as those in the structural pillars of the vehicle and in the sheet metal of the vehicle doors. In order to minimize the transfer of noise, vibration, smoke, dust, water, moisture, etc. from one area of the vehicle to another, it is often desirable to seal such orifices and cavities with sealing members or shielding components incorporated therein. Similarly, such members or components often further serve to reinforce the hollow structure of the manufactured article, such as an automotive part, while still retaining the advantage of the lightweight of the hollow structure while having a higher mechanical stress resistance.

[0003] Such components used for sealing, shielding, or reinforcement often consist of a support made of plastic, metal, or other rigid material, and one or more layers adhered thereto of a thermoplastic material capable of expanding when heat or other physical or chemical forms of energy are applied, although they may be made entirely of expandable material. With appropriate design, it is possible not only to insert the shielding or reinforcing component into the hollow part of the structure during the manufacturing process, but also to leave the inner wall of the structure as a structure (or a passable cavity) such that, for example, liquid can still reach it. For example, during the vehicle manufacturing process, most of the hollow part of the metal frame is left with the shielding or reinforcing component inserted, still covered with electrocoating ("e-coat") liquid, and then during the baking step, the expandable thermoplastic material of the shielding or reinforcing component is expanded to fill the cavity as intended.

[0004] The development of shielding or reinforcing components in this way has led to highly evolved systems where the expandable material expands its volume to thousands of percent to form a stable, cross-linked foam-like structure that fills the cavity and adheres to the walls of the structure to achieve the purpose of sealing, shielding, or strengthening. In vehicle manufacturing in particular, this has led to significant weight reduction and excellent attenuation of noise or vibration in the vehicle body.

[0005] Currently employed heat-expandable compositions generally consist of polymers that can be crosslinked, for example, by a radical initiator, most commonly a peroxide, such as an ethylene-vinyl acetate polymer. To obtain a foam, these compositions further contain a blowing agent, with the most widely used being azodicarbonamide (also called azodicarboxamide or azobisformamide), and 4,4'-oxydibenzenesulfonyl hydrazide (abbreviation: OBSH). Under activation conditions such as high temperature, the crosslinkable network hardens while the blowing agent decomposes to release gas. This results in the above-mentioned volume expansion and the formation of a stable foam that, ideally, fills its cavities as intended and adheres to its walls. Such a system is disclosed, for example, in German Patent Application Publication No. 10 2011 080 223 A1.

[0006] However, before an expanded and stable foam is formed, known heat-expandable compositions are particularly susceptible to the influence of moisture and thus have only a rather limited storage stability. For example, water absorbed into the composition during storage under high humidity conditions can react with the free radical polymerization initiator, reducing the crosslink density and potentially leading to a loss of expansion and the formation of an open cell structure. Furthermore, the reduced expansion rate and open cell structure result in a decrease in the sealing performance of the material.

[0007] Therefore, it is desirable to obtain a heat-expandable composition with improved resistance to storage in the wet state, i.e., a composition that exhibits only a low expansion loss even after storage under high temperature and high humidity conditions. SUMMARY OF THE INVENTION PROBLEM TO BE SOLVED BY THE INVENTION

[0008] The object of the present invention is to provide a heat-expandable composition that expands homogeneously over a wide temperature range, cures to form a stable foam structure, and whose composition exhibits improved stability against water / moisture. Furthermore, the foam thus produced should exhibit good adhesion to metal surfaces, and furthermore oily surfaces, as well as other equipment, which are commonly used in manufactured articles, particularly motor vehicles.

Means for Solving the Problems

[0009] The subject of the present invention is a heat-expandable composition as defined in claim 1.

[0010] Surprisingly, it has been found that it is possible to improve the wet storage resistance of a heat-expandable composition by using a compound having a hydrolyzable silane group. Without being bound by any theory, it is thought that during wet storage, a small amount of the silane groups reacts with water, and as a result, the polymer chains are partially crosslinked before the baking step. Furthermore, at least some of the silane groups react during the baking process with the water absorbed by the substance during wet storage, resulting in further crosslinking of the polymer chains. The silane-crosslinking reaction that occurs either during wet storage or during the baking step compensates for the decrease in crosslink density caused by the reaction between the absorbed water and a free radical crosslinking agent such as a peroxide.

[0011] One advantage of the heat-expandable composition of the present invention is that it is possible to improve the wet storage resistance without adversely affecting other properties related to the use of the heat-expandable composition. The desired effect can also be obtained by using a relatively small amount of a compound containing a hydrolyzable silane group.

[0012] Other subjects of the present invention are presented in the other independent claims. Preferred embodiments of the present invention are presented in the dependent claims.

Mode for Carrying Out the Invention

[0013] The subject of the present invention is an expandable composition upon heating, comprising: (a) at least one polymer P, (b) at least one free radical polymerization initiator I, and (c) at least one chemical blowing agent CBA, and (d) optionally, at least one epoxy-functional polymer EP, wherein the composition is an expandable composition upon heating and contains a silane group of the following formula (I):

Chemical formula

[0014] The term "polymer" refers to a chemically homogeneous group of macromolecules produced by a polymerization reaction (polymerization, polyaddition, polycondensation), where the macromolecules differ in terms of degree of polymerization, molecular weight, and chain length. This term includes derivatives of said generic macromolecules obtained as a result of the polymerization reaction, i.e., compounds obtained, for example, by an addition reaction or substitution reaction of functional groups in a predefined macromolecule, and they may be either chemically homogeneous or chemically heterogeneous.

[0015] The term "silane" refers first to a compound having at least one, conventionally two or three, hydrolysable groups directly bonded to a silicon atom via Si - O - bonds, more specifically an alkoxy group or an acyloxy group, and second to a compound having at least one organic group directly bonded to a silicon atom via an Si - C bond. Silanes having an alkoxy group or an acyloxy group are also known to those skilled in the art as organoalkoxysilanes and organoacyloxysilanes respectively. Thus, tetraalkoxysilane is not a silane in this definition.

[0016] Accordingly, the term "silane group" refers to a silicon - containing group bonded to an organic carbon group via an Si - C bond. Silanes and their silane groups have the property of hydrolysing upon contact with moisture. By doing so, they form organosilanols (which are organosilicon compounds containing one or more silanol groups (Si - OH groups)), and then, by a condensation reaction, organosiloxanes (which are organosilicon compounds containing one or more siloxane groups (Si - O - Si groups)).

[0017] The terms "silane - functionalized" and "silane - functional" refer to compounds containing a silane group. The terms "silane - functionalized polymer" and "silane - functional polymer" thus refer to polymers containing at least one silane group.

[0018] The term "molecular weight" refers to the molar mass (g / mol) of a molecule or a part of a molecule (also called a "moiety"). The term "average molecular weight" refers to the number - average molecular weight (M n) is being pointed at. The molecular weight can be measured by a commonly used method, preferably gel permeation chromatography (GPC). In that case, at 35 °C, polystyrene as the standard, a styrene-divinylbenzene gel with porosities of 100 Å, 1000 Å, and 10000 Å as the column, and tetrahydrofuran as the solvent are used.

[0019] The term "softening point" or "softening temperature" refers to the temperature at which a compound softens to a rubbery state or the temperature at which the crystalline portions in the compound melt. The softening point can be determined by the ring and ball method as specified in the DIN EN 1238 standard.

[0020] The term "melting temperature" refers to the temperature at which a substance transitions from a solid state to a liquid state. The melting temperature (T m ) is preferably determined by differential scanning calorimetry (DSC) according to the ISO 11357-3 standard, using a heating rate of 2 °C / min. The measurement can be carried out using a Mettler Toledo DSC3+ device, and the T m value can be determined from the measured DSC curve using DSC software. When the measured DSC curve shows multiple peak temperatures, the temperature of the first peak from the low-temperature side in the thermogram is regarded as the melting temperature (T m ).

[0021] The term "amount or content of at least one component X in the composition", for example, "the amount of the at least one polymer P", refers to the sum of the individual amounts of all the polymer P contained in the composition. For example, when at least one polymer P occupies 20% by weight of the total weight of the composition, the sum of the amounts of all the polymer P contained in the composition is equal to 20% by weight.

[0022] The term "room temperature" refers to a temperature of 23°C.

[0023] There are no special restrictions on the amount of the silane group of formula (I) in the heat-expandable composition. However, in order to have improved moisture resistance, a minimum amount of moisture-reactive groups is required, but it has been found that increasing the amount of the silane group beyond a certain limit results in a decrease in the initial expansion ratio before storage in the wet state, especially at high temperatures exceeding 185°C.

[0024] In one or more preferred embodiments, the heat-expandable composition contains 0.05 to 10.0% by weight, preferably 0.15 to 7.5% by weight, more preferably 0.20 to 5.0% by weight, and even more preferably 0.25 to 3.5% by weight of the silane group of formula (I), based on the total weight of the heat-expandable composition. It has been found that adding the silane group to the heat-expandable composition in an amount falling within the defined range substantially improves the stability during storage in the wet state. Specifically, such a heat-expandable composition stored at a temperature of 40°C and a relative humidity of 100% for one week showed a significantly lower expansion loss compared to a reference example composition containing a smaller amount of the silane group of formula (I).

[0025] It is preferred that at least a part of the silane group of formula (I) is bonded to at least one polymer P and / or the heat-expandable composition further contains at least one alkoxysilane SI of the following formula (II): [Chemical formula] [In the formula, R 1 and R 2 are as defined above, and R 3 represents a linear, branched, or cyclic alkenyl group having 1 to 20 carbon atoms, preferably 1 to 10 carbon atoms.]

[0026] In 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, and still more preferably at least 95% by weight of the silane groups of formula (I) are bonded to at least one polymer P. In one or more embodiments, all of the silane groups of formula (I) contained in the thermally expandable composition are bonded to at least one polymer P.

[0027] In one or more embodiments, at least one alkoxysilane SI of formula (II) is selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris(2-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyldimethylmethoxysilane, and vinylmethyldibutoxysilane, preferably from the group consisting of vinyltrimethoxysilane and vinyltriethoxysilane.

[0028] In one or more embodiments, at least one polymer P is a silane-functionalized polymer containing a silane group of formula (I), preferably an organic silane-functionalized polymer containing a silane group of formula (I).

[0029] As used herein, the term "organic polymer" includes a group of macromolecules that are chemically homogeneous but differ in terms of degree of polymerization, molar mass, and chain length and contain a very large number of carbon atoms in their polymer backbone, as well as reaction products of such groups of macromolecules. Polymers having a polyorganosiloxane main chain (commonly referred to as "silicones") are not organic polymers in the context of the present disclosure.

[0030] Suitable silane-functionalized polymers for use as at least one polymer P may contain polymerized or grafted silane functional groups, i.e., the silane groups of formula (I) may be present as part of the polymer backbone or may be grafted onto the polymer as side chains.

[0031] In one or more embodiments, the at least one polymer P is obtained by grafting one or more alkoxysilanes of formula (II) onto the polymer chains of one or more polymers or by copolymerizing one or more alkoxysilanes of formula (II) with one or more comonomers. Suitable comonomers for copolymerizing 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" represents both acrylate and methacrylate in the present disclosure.

[0032] In one or more embodiments, the at least one polymer P is 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, where the at least one starting polymer is preferably selected from the group consisting of: polyethylene, ethylene-α-olefin copolymer, polypropylene, propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, olefin-(meth)acrylate copolymer, olefin-(meth)acrylic acid alkyl copolymer, and olefin-(meth)acrylic acid copolymer.

[0033] The term "α-olefin" has the molecular formula C x H 2xrepresents an alkene having (where x corresponds to the number of carbon atoms) and is characterized by a carbon-carbon double bond at the first carbon atom (α-carbon). Examples of α-olefins include the following: ethylene, propylene, 1-butene, 2-methyl-1-propene (isobutylene), 1-pentene, 1-hexene, 1-heptene, and 1-octene. For example, none of 1,3-butadiene, 2-butene, or styrene are considered "α-olefins" in the present disclosure. The term "poly-α-olefin" represents homopolymers and copolymers obtained by polymerizing or oligomerizing α-olefins, or a plurality of different α-olefins.

[0034] In one or more embodiments, at least one of the polymers P is selected from the group consisting of ethylene-vinyl acetate copolymers grafted with silane, polyolefins grafted with silane, olefin-silane copolymers, and olefin-(meth)acrylate alkyl-silane terpolymers, preferably selected from the group consisting of ethylene-vinyl acetate copolymers grafted with silane, olefin-silane copolymers, and olefin-(meth)acrylate alkyl-silane terpolymers, more preferably selected from the group consisting of ethylene-vinyl acetate copolymers grafted with silane, and olefin-(meth)acrylate alkyl-silane terpolymers.

[0035] In one or more embodiments, at least one polymer P comprises or consists of at least one ethylene-vinyl acetate copolymer grafted with at least one silane, wherein the at least one ethylene-vinyl acetate copolymer grafted with at least one silane 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. Generally, the expression "at least one component X comprises at least one component N", for example, "at least one polymer P comprises at least one ethylene-vinyl acetate copolymer grafted with at least one silane" should be understood to mean, in the context of the present disclosure, that the composition comprises, as represented by at least one polymer P, one or more ethylene-vinyl acetate copolymers grafted with at least one silane.

[0036] In one or more embodiments, at least one polymer P comprises or consists of at least one ethylene-vinyl acetate copolymer grafted with at least one silane, wherein the at least one ethylene-vinyl acetate copolymer grafted with at least one silane 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.

[0037] In one or more embodiments, at least one polymer P comprises or consists of: at least one olefin-silane copolymer, or an olefin-(meth)acrylate alkyl-silane terpolymer, preferably at least one olefin-(meth)acrylate alkyl-silane terpolymer.

[0038] In one or more embodiments, at least one polymer P comprises, or consists of, an ethylene-vinyl acetate copolymer P1 grafted with at least one first silane and an ethylene-vinyl acetate copolymer P2 grafted with at least one second silane different from the at least one first silane, wherein the polymer P1 grafted with the at least one first silane 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 polymer P2 grafted with the at least one second silane 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.

[0039] In one or more embodiments, the weight ratio of the total amount of the ethylene-vinyl acetate copolymer P1 grafted with the at least one first silane to the ethylene-vinyl acetate copolymer P2 grafted with the at least one second silane is in the range from (5:1) to (1:3), preferably from (3:1) to (1:2), more preferably from (2.5:1) to (1:1).

[0040] In one or more further embodiments, the expandable composition upon heating further comprises at least one alkoxysilane SI of formula (II).

[0041] The heat-expandable composition further contains at least one free-radical polymerization initiator I. It is known that when exposed to a sufficient amount of energy such as radiation, heat, etc., all types of free-radical polymerization initiators that can decompose to generate radicals capable of initiating the desired curing (crosslinking) reaction are, in principle, considered suitable for use as the at least one free-radical polymerization initiator I.

[0042] In one or more embodiments, the at least one free-radical polymerization initiator I is a peroxide polymerization initiator PI, preferably an organic peroxide.

[0043] Suitable peroxide polymerization initiators are substantially inert at room temperature (23 °C) and exhibit an activation temperature suitable for the intended purpose. For example, if the heat-expandable composition is to be used to obtain shielding and / or reinforcing components in the manufacture of automobiles, typically an activation temperature in the range of 90 to 250 °C is preferred. Furthermore, it is advantageous for the at least one peroxide polymerization initiator PI to have an activation temperature compatible with the decomposition temperature of at least one chemical blowing agent CBA. If the difference between the above two temperatures is too large, it may be more difficult to obtain a heat-expandable composition having optimal performance and stability.

[0044] Furthermore, it may be advantageous if at least one of the peroxide polymerization initiators PI has a half-life of 10 hours as measured in benzene or a similar non-polar solvent at a temperature in the range of 90 to 130°C. In the case of certain types of peroxide polymerization initiators, solvents other than benzene, such as toluene, triethyl phosphate, or dibutyl phthalate, may be more suitable for the measurement of the half-life. In the case of embodiments at extremely low temperatures, i.e., optimized for expansion between 120°C and 150°C, a peroxide polymerization initiator having a half-life of 10 hours at a temperature in the range of 50 to 100°C is preferred. It is further advantageous if at least one of the peroxide polymerization initiators PI is compatible with and / or miscible with the polymer matrix of the heat-expandable composition. In some cases, the compatibility between the peroxide polymerization initiator and the polymer matrix can be further improved by using processing aids and other compatibilizing additives.

[0045] Suitable peroxide polymerization initiators include, in particular, organic peroxides. All types of organic peroxides, which are known to generate radicals that can decompose upon heating to initiate the desired curing (crosslinking) reaction, are considered in principle suitable for use as at least one of the peroxide polymerization initiators PI.

[0046] In one or more embodiments, at least one peroxide polymerization initiator PI is preferably an organic peroxide selected from the group consisting of ketone peroxides, diacyl peroxides, peresters, perketals, and hydroperoxides. Examples of suitable peroxides include the following: cumene hydroperoxide, t-butyl peroxide, bis(t-butylperoxy)-diisopropylbenzene, di(t-butylperoxyisopropyl)benzene, dicumyl peroxide, t-butyl peroxybenzoate, di-alkyl peroxydicarbonate, diperoxyketal (e.g., 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane), ketone peroxide (e.g., methyl ethyl ketone peroxide), and 4,4-di-t-butylperoxy-n-butyl valerate.

[0047] Particularly suitable organic peroxides include the following: 3,3,5,7,7-pentamethyl-1,2,4-trioxepane, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, di-t-butyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, t-butyl cumyl peroxide, di(t-butylperoxyisopropyl)benzene, dicumyl peroxide, butyl-4,4-di(t-butylperoxy)valerate, t-butyl peroxy-2-ethylhexyl carbonate, 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane, t-butyl peroxybenzoate, di(4-methylbenzoyl)peroxide, and dibenzoyl peroxide.

[0048] In one or more embodiments, at least one peroxide polymerization initiator PI is selected from the group consisting of dicumyl peroxide, and / or di(t-butylperoxyisopropyl)benzene, and / or 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane.

[0049] They are commercially available under the following product names, for example: the product name Perkadox® BC-40B-PD (manufactured by Akzo Nobel) and Peroxan® DC-40 PK (manufactured by Pergan) (dicumyl peroxide); the product name Perkadox® 14-40B-PD (manufactured by Akzo Nobel) and Peroxan® BIB-40 P (manufactured by Pergan) (di(t-butylperoxyisopropyl)benzene); and the product name Peroxan® PK295 (manufactured by Pergan) (di(t-butylperoxyisopropyl)benzene).

[0050] In one or more embodiments, at least one peroxide polymerization initiator PI is included in an amount of 0.01 to 10.0 wt%, preferably 0.025 to 7.5 wt%, more preferably 0.05 to 5.0 wt%, even more preferably 0.1 to 3.5 wt%, still more preferably 0.15 to 3.5 wt%, and most preferably 0.25 to 3.0 wt% of the total weight of the heat-expandable composition.

[0051] Furthermore, it is advantageous for at least one peroxide polymerization initiator PI to be present in the heat-expandable composition in a form immobilized on a carrier material such as silica, kaolin, and / or calcium carbonate, or a suitable material. This approach facilitates the handling, metering, and uniform dispersion of at least one peroxide polymerization initiator PI in the heat-expandable composition. Examples of immobilized organic peroxides include, for example: 40 wt% dicumyl peroxide on calcium carbonate, 40 wt% di(t-butylperoxyisopropyl)benzene on clay and silica, and 40 wt% 1,1-di(t-butylperoxy)-3,3,5-trimethylcyclohexane on calcium carbonate. In these embodiments, the expression "the amount of at least one peroxide polymerization initiator PI" refers to the amount of the active substance contained in the heat-expandable composition, excluding the amount of the carrier material on which at least one peroxide polymerization initiator PI, for example, an organic peroxide, is immobilized.

[0052] In one or more embodiments, at least one free radical polymerization initiator I is preferably an azo-polymerization initiator AI selected from the group consisting of azonitrile compounds, alkyl azo compounds, and azoamide compounds.

[0053] Suitable azo polymerization initiators are substantially inert at normal room temperature (23 °C) and exhibit an activation temperature suitable for the intended purpose. For example, when the heat-expandable composition is to be used to obtain shielding and / or reinforcing components in the manufacture of automobiles, typically an activation temperature in the range of 90 to 250 °C is preferred. Furthermore, it is advantageous for at least one azo polymerization initiator AI to have an activation temperature compatible with the decomposition temperature of at least one chemical blowing agent CBA. If the difference between the above two temperatures is too large, it may be more difficult to obtain a heat-expandable composition having optimal performance and stability.

[0054] Furthermore, it may be advantageous if at least one azo polymerization initiator AI has a half-life of 10 hours when measured in toluene or a similar non-polar solvent at a temperature in the range of 55 to 120 °C. For certain types of azo polymerization initiators, it may also be more suitable to use a solvent other than toluene, such as a substituted (e.g., chlorinated) benzene, methanol, or water, for the measurement of its half-life. The selection of a suitable solvent mainly depends on the solubility of the azo polymerization initiator in each solvent. It is further advantageous if at least one azo polymerization initiator AI is compatible and / or miscible with the polymer matrix of the heat-expandable composition. In some cases, the compatibility between the azo polymerization initiator and the polymer matrix can be further improved by using processing aids and other compatibilizing additives.

[0055] Examples of azo polymerization initiators suitable for use as the at least one azo polymerization initiator AI include the following: 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), di-tert-butyl-4,4-azobis-(4-cyanoperoxypentanoate), di-tert-butyl-4,4-azobis-(4-cyanoperoxyhexanoate), di-tert-butyl-4,4-azobis-(4-cyanoperoxyheptanoate), dimethyl-2,2'-azobis(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].

[0056] In one or more embodiments, the at least one azo polymerization initiator AI is selected from the group consisting of azobisisobutyronitrile (AIBN), 1,1'-azobis(cyclohexane-1-carbonitrile) (ACHN), and 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide].

[0057] In one or more embodiments, the at least one azo polymerization initiator AI is included in an amount of 0.1 to 10.0% by weight, preferably 0.15 to 7.5% by weight, more preferably 0.25 to 5.0% by weight, even more preferably 0.25 to 3.5% by weight, still more preferably 0.35 to 3.5% by weight, and most preferably 0.5 to 3.5% by weight of the total weight of the thermally expandable composition.

[0058] The heat-expandable composition further contains at least one chemical blowing agent CBA. The chemical blowing agent is an organic or inorganic compound that decomposes, for example, under the influence of temperature or moisture, and at least one decomposition reaction product formed thereby is a gas. 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.

[0059] Examples of exothermic chemical blowing agents suitable for use as at least one chemical blowing agent CBA include, for example: azodicarbonamide, azoisobutyronitrile, azocyclohexylnitrile, dinitrosopentamethylenetetramine, azodiaminobenzene, benzene-1,3-sulfonylhydrazide, calcium azide, 4,4'-diphenyldisulfonyl azide, p-toluenesulfonylhydrazide, p-toluenesulfonyl semicarbazide, 4,4'-oxybis(benzenesulfonylhydrazide), trihydrazinotriazine, and N,N'-dimethyl-N,N'-dinitrosoterephthalamide, and combinations thereof.

[0060] In one or more embodiments, the at least one chemical blowing agent CBA comprises one or more selected from the group consisting of azodicarbonamide, dinitrosopentamethylenetetramine, and 4,4'-oxybis(benzenesulfonylhydrazide), most preferably comprises or consists of azodicarbonamide.

[0061] In heat-expandable compositions, especially in the automotive industry, there may be cases where it is preferable to provide heat-expandable compositions that do not contain exothermic chemical blowing agents, despite the fact that they are widely used. Exothermic blowing agents are not always preferable because they have been found to trigger sensitization of the respiratory system, to generally not be safe from a toxicological perspective, or to have an explosion hazard. Moreover, when exothermic blowing agents decompose, by-products such as ammonia, formamide, formaldehyde, or nitrosoamine are released, and these substances are classified as hazardous substances, and their use is prohibited in automotive manufacturing.

[0062] In one or more further embodiments, at least one of the chemical blowing agents CBA is an endothermic chemical blowing agent. Endothermic chemical blowing agents have the advantage of not being dangerous or explosive and of generating little to no volatile organic compounds (VOCs) when they decompose. The decomposition reaction products are substantially carbon dioxide and water.

[0063] In one or more embodiments, at least one of the chemical blowing agents CBA is an endothermic chemical blowing agent that contains at least one organic acid. Suitable organic acids for use in endothermic chemical blowing agents include, for example, the following: monocarboxylic acids such as acetic acid and propionic acid, and further 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.

[0064] In one or more embodiments, at least one of the chemical blowing agents CBA contains at least 85% by weight, preferably at least 90% by weight, more preferably at least 95% by weight, even more preferably at least 97.5% by weight, and still more preferably at least 99% by weight of at least one organic acid, based on the total weight of at least one of the chemical blowing agents CBA.

[0065] In one or more embodiments, at least one of the organic acids 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, particularly at least one free carboxyl group, are also suitable. In one or more embodiments, at least one of the organic acids has a molecular weight of 1000 g / mol or less, preferably 750 g / mol or less, more preferably 500 g / mol or less.

[0066] In a further embodiment, at least one of the chemical blowing agents CBA comprises or consists of at least one organic acid selected from the group consisting of citric acid, tartaric acid, malic acid, fumaric acid, and maleic acid, preferably citric acid.

[0067] At least one of the organic acids can be present in the heat-expandable composition in the form of the free acid, i.e., as a protonated acidic functional group, or as a salt having a deprotonated acidic functional group, such as a carboxylate, or as a mixture thereof. Suitable cations for the carboxylate include, for example, Li + , Na + , K + , NH4 + , Ca 2+ , Mg 2+ and the like. In one or more embodiments, at least one of the organic acids is present in the heat-expandable composition in acid form.

[0068] In one or more embodiments, at least one chemical blowing agent CBA has a maximum decomposition peak temperature in the range of 135 to 235 °C, preferably 150 to 225 °C, more preferably 155 to 200 °C, and even more preferably 160 to 200 °C, as measured by differential scanning calorimetry (DSC). Preferably, the maximum decomposition peak measured by DSC is measured by a DSC822e differential scanning calorimeter (manufactured by Mettler-Toledo), holding the sample at 25 °C for 2 minutes, 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 minutes, and finally cooling the sample from 280 °C to 25 °C at a rate of 10 °C / min.

[0069] There is no particular limitation on the amount of at least one chemical blowing agent CBA contained in the heat-expandable composition, but the preferred amount depends on the desired expansion ratio. In one or more embodiments, at least one chemical blowing agent CBA occupies 1 to 20% by weight, preferably 2.5 to 15% by weight, more preferably 5 to 15% by weight, and even more preferably 5 to 10% by weight of the total weight of the heat-expandable composition.

[0070] In one or more embodiments, the heat-expandable composition further contains at least one epoxy-functional polymer EP.

[0071] Preferably, at least one epoxy-functional polymer EP has an average of two or more epoxy groups per molecule. Further, at least one epoxy-functional polymer EP may contain an epoxy functional group that is either polymerized or grafted, i.e., the epoxide residue may be present as part of the polymer backbone or grafted as a side chain onto the polymer. Such an epoxy-functional polymer can be added to the heat-expandable composition, for example, as an adhesion promoter, to improve the adhesion of the expanded composition on an oil-coated surface, such as oil-coated steel commonly found in the manufacture of automobiles.

[0072] In one or more embodiments, at least one epoxy-functional polymer EP is selected from the group consisting of: olefin-(meth)acrylic acid glycidyl copolymers, olefin-(meth)acrylic acid alkyl-(meth)acrylic acid glycidyl terpolymers, and glycidyl methacrylate grafted (co)polymers. It should be understood that the term "(co)polymer" includes homopolymers, copolymers, random copolymers, block copolymers, and terpolymers.

[0073] Suitable olefin-(meth)acrylic acid glycidyl copolymers used as at least one epoxy-functional polymer EP include, for example, copolymers of ethylene, propylene, or butylene with glycidyl acrylate (GA) or glycidyl (meth)acrylate (GMA).

[0074] In one or more embodiments, at least one epoxy-functional polymer EP preferably includes at least one olefin-(meth)acrylic acid glycidyl copolymer EP1 selected from the group consisting of ethylene-(meth)acrylic acid glycidyl copolymers, propylene-(meth)acrylic acid glycidyl copolymers, and butylene-(meth)acrylic acid glycidyl copolymers, more preferably selected from the group consisting of ethylene-(meth)acrylic acid glycidyl copolymers, particularly preferably selected from ethylene-glycidyl methacrylate copolymers.

[0075] In one or more embodiments, at least one olefin-(meth)acrylic acid glycidyl copolymer EP1 has - a glycidyl methacrylate content of 1 to 50% by weight, more preferably 2 to 25% by weight, and / or - a melt flow index determined according to ISO 1133 (190°C / 2.16 kg) of 100 g / 10 min or less, preferably 75 g / 10 min or less, more preferably 50 g / 10 min or less, and even more preferably 25 g / 10 min or less, and / or - The melting temperature (T m ) determined by the DSC measurement method carried out in accordance with ISO 11357-3 in the range of 150 °C or lower, preferably 135 °C or lower, particularly 75 to 150 °C, preferably 85 to 135 °C, more preferably 90 to 125 °C has.

[0076] In one or more embodiments, at least one of the epoxy-functional polymers EP is preferably selected from the group consisting of ethylene-(meth)acrylic acid glycidyl copolymers, propylene-(meth)acrylic acid glycidyl copolymers, and butylene-(meth)acrylic acid glycidyl copolymers, more preferably selected from the group consisting of ethylene-(meth)acrylic acid glycidyl copolymers, particularly selected from ethylene-methacrylic acid glycidyl copolymers, and is composed of at least one olefin-(meth)acrylic acid glycidyl copolymer EP1. Generally, the expression "at least one component X is composed of at least one component XN", for example, "at least one of the epoxy-functional polymers EP is composed of at least one olefin-(meth)acrylic acid glycidyl copolymer EP1", in the context of the present disclosure, is understood to mean that at least one of the epoxy-functional polymers EP is selected from the group consisting of at least one olefin-(meth)acrylic acid glycidyl copolymer EP1.

[0077] Examples of the olefin-(meth)acrylic acid alkyl-(meth)acrylic acid glycidyl terpolymer suitable for use as at least one of the epoxy-functional polymers EP include terpolymers, particularly random terpolymers of ethylene and (meth)acrylic acid alkyl and glycidyl acrylate (GA) or glycidyl methacrylate (GMA), where the alkyl group of the (meth)acrylic acid alkyl is preferably selected from the group consisting of methylene, ethylene, propylene, and butylene, particularly methylene or butylene.

[0078] Examples of preferred olefin-(meth)acrylic acid alkyl-(meth)acrylic acid glycidyl 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), 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-ethyl methacrylate-glycidyl methacrylate terpolymer (E / EMA / GMA), ethylene-propyl methacrylate-glycidyl methacrylate terpolymer (E / PMA / GMA), ethylene-butyl methacrylate-glycidyl methacrylate terpolymer (E / BMA / GMA).

[0079] In one or more embodiments, at least one of the epoxy-functional polymers EP includes at least one olefin-alkyl acrylate-glycidyl (meth)acrylate terpolymer EP2, preferably a random terpolymer selected from the group consisting of ethylene, alkyl (meth)acrylate, and glycidyl methacrylate, wherein the alkyl group of the alkyl (meth)acrylate is preferably selected from the group consisting of methylene, ethylene, propylene, and butylene, particularly from the group consisting of methylene or butylene.

[0080] In one or more embodiments, at least one of the olefin-alkyl acrylate-glycidyl (meth)acrylate terpolymers EP2 has - a glycidyl methacrylate content of from 1 to 50% by weight, more preferably from 2 to 25% by weight, and / or - a melt flow index determined according to ISO 1133 (190 °C / 2.16 kg) of 100 g / 10 min or less, preferably 75 g / 10 min or less, more preferably 50 g / 10 min or less, and / or - a melting temperature (T m ) determined by DSC measurement carried out according to ISO 11357-3 in the range of 150 °C or less, preferably 135 °C or less, particularly 75 to 150 °C, preferably 85 to 135 °C, more preferably 90 to 125 °C. has.

[0081] In one or more embodiments, at least one of the epoxy-functional polymers EP consists of at least one olefin-alkyl acrylate-glycidyl (meth)acrylate terpolymer EP2, preferably a random terpolymer selected from the group consisting of ethylene, alkyl (meth)acrylate, and glycidyl methacrylate, wherein the alkyl group of the alkyl (meth)acrylate is preferably selected from the group consisting of methylene, ethylene, propylene, and butylene, particularly from the group consisting of methylene or butylene.

[0082] Examples of the glycidyl (meth)acrylate grafted (co)polymers suitable for use as the at least one epoxy-functional polymer EP include the following: glycidyl methacrylate grafted olefin-vinyl acetate copolymer, glycidyl methacrylate grafted ethylene-α-olefin copolymer, glycidyl methacrylate grafted propylene-α-olefin copolymer, glycidyl methacrylate grafted polyethylene, glycidyl methacrylate grafted polypropylene, and glycidyl methacrylate grafted olefin copolymer elastomer, glycidyl (meth)acrylate grafted styrene-butadiene copolymer, and glycidyl (meth)acrylate grafted styrene-ethylene-butylene-styrene terpolymer.

[0083] In one or more embodiments, the at least one epoxy-functional polymer EP preferably includes at least one glycidyl methacrylate grafted (co)polymer EP3 selected from the group consisting of the following: glycidyl methacrylate grafted olefin-vinyl acetate copolymer, glycidyl methacrylate grafted ethylene-α-olefin copolymer, glycidyl methacrylate grafted propylene-α-olefin copolymer, glycidyl methacrylate grafted polyethylene, glycidyl methacrylate grafted polypropylene, glycidyl (meth)acrylate grafted styrene-butadiene copolymer, and glycidyl (meth)acrylate grafted styrene-ethylene-butylene-styrene terpolymer.

[0084] In one or more embodiments, the at least one glycidyl methacrylate grafted (co)polymer EP3 has - a glycidyl methacrylate (GMA) content 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, and particularly 0.1 to 1.5% by weight, and / or - A melt flow index determined according to ISO 1133 (190 °C / 2.16 kg) of 100 g / 10 min or less, preferably 75 g / 10 min or less, more preferably 50 g / 10 min or less, and / or - A melting temperature (T m ) determined by a DSC measurement method carried out according to ISO 11357-3 in the range of 150 °C or less, preferably 135 °C or less, particularly 75 - 150 °C, preferably 85 - 135 °C, more preferably 90 - 125 °C. It has.

[0085] In one or more embodiments, at least one epoxy-functional polymer EP is preferably composed of at least one glycidyl methacrylate-grafted (co) polymer EP3 selected from the group consisting of: glycidyl methacrylate-grafted olefin-vinyl acetate copolymer, glycidyl methacrylate-grafted ethylene-α-olefin copolymer, glycidyl methacrylate-grafted propylene-α-olefin copolymer, glycidyl methacrylate-grafted polyethylene, glycidyl methacrylate-grafted polypropylene, (meth) acrylic acid glycidyl-grafted styrene-butadiene copolymer, and (meth) acrylic acid glycidyl-grafted styrene-ethylene-butylene-styrene terpolymer.

[0086] If at least one epoxy-functional polymer EP is used, it is preferably present in the heat-expandable composition in an amount of 0.5 - 35% by weight, preferably 2.5 - 30% by weight, more preferably 5 - 30% by weight, even more preferably 10 - 25% by weight, still more preferably 10 - 20% by weight, based on the total weight of the heat-expandable composition.

[0087] In one or more embodiments, the heat-expandable composition further contains at least one activator A containing at least one compound of the following formula (III):

Chemical formula

[0088] Preferably, R 4 and R 5 each independently represents 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, and in some cases they combine to represent a divalent alkyl group that forms a ring structure together with the adjacent nitrogen atom, and / or R 6 and R 7 each independently represents 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, and they may combine in some cases to represent a divalent alkyl group that forms a ring structure together with the adjacent nitrogen atom.

[0089] Compounds of formula (III) that are preferably used as at least one activator A include, among those of formula (III), those in which both R 4 and R 5 represent hydrogen atoms, and / or those in which both R 6 and R 7 represent an ethyl or methyl group, preferably a methyl group. More preferably, among the compounds of formula (III), R 4 and R 5, R 6 , and R 7 all represent an ethyl or methyl group, preferably a methyl group, or R 4 , R 5 , and R 6 represent an ethyl or methyl group, preferably a methyl group, and R 7 represents a hydrogen atom, or R 4 and R 7 both represent a hydrogen atom, and R 5 and R 6 both represent an ethyl or methyl group, preferably a methyl group. Examples include those where

[0090] In one or more embodiments, at least one activator A includes or consists of one or more compounds selected from the group consisting of: 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 (where all or part of the methyl groups are replaced with ethyl groups).

[0091] Suitable urea activators are commercially available, for example, under the trade names Dyhard® (manufactured by AlzChem Group AG), Omicure® (manufactured by CVC Thermoset Specialties), and Amicure® (manufactured by Evonik).

[0092] In one or more preferred embodiments, at least one activator A has R 5 and R 6 both representing hydrogen atoms, R 4 and R 7Both represent a methyl group, and n has a value of 1, the compound according to formula (III) (therefore, represented as N,N-dimethylurea) is included or consists of this. This activator A is particularly suitable for use in combination with a chemical blowing agent CBA containing azodicarbonamide. With this type of activator - blowing agent combination, exceptionally excellent expansion volume and highly stable foam can be obtained over the entire temperature range of at least 140°C to 200°C, and expansion of at least 1000%, preferably at least 1100%, can be obtained anywhere within that temperature range.

[0093] In one or more further preferred embodiments, at least one of the activators A is R 4 R 5 R 6 and R 7 all represent hydrogen atoms, the compound according to formula (III) (therefore, represented as urea) is included or consists of them. This activator A is particularly suitable for use in combination with a chemical blowing agent CBA containing 4,4'-oxybis(benzenesulfonylhydrazide). With this type of activator - blowing agent combination, an exceptionally excellent expansion volume can be obtained over the entire temperature range of at least 140°C to 200°C, and expansion of at least 1000%, preferably at least 1100%, can be obtained anywhere within that temperature range.

[0094] If at least one of the activators A is used, it is preferably present in an amount of 1 to 10% by weight, more preferably 1 to 9% by weight, even more preferably 1.5 to 8% by weight, based on the total weight of the heat-expandable composition, in the heat-expandable composition.

[0095] It is highly recommended to optimize the amount of at least one activator A with respect to the amount of at least one chemical blowing agent CBA. For example, the at least one activator A is used in an amount of 10 to 80% by weight, more preferably 12 to 65% by weight, even more preferably 15 to 55% by weight, and still more preferably 20 to 45% by weight, based on the total weight of the at least one chemical blowing agent CBA contained in the heat-expandable composition.

[0096] Furthermore, it is advantageous for the heat-expandable composition to contain at least one secondary activator SA in combination with at least one activator A. Examples of compounds suitable for use as at least one secondary activator SA include, for example, the following: zinc compounds such as zinc oxide, zinc acetate, zinc stearate, zinc bis(p-toluenesulfinate), or zinc bis(benzenesulfinate), titanium oxide, and magnesium oxide, as well as fatty acids having at least 6 carbon atoms such as stearic acid and montanic acid. Preferred secondary activators are zinc compounds, particularly zinc oxide, and mixtures of zinc compounds, particularly mixtures of zinc oxide and zinc acetate, and fatty acids having at least 6 carbon atoms. These types of secondary activators can be added to the heat-expandable composition in an amount of 1 to 10% by weight, preferably 1.25 to 7.5% by weight, more preferably 1.4 to 5% by weight, based on the total weight of the heat-expandable composition.

[0097] Furthermore, it is also highly recommended to optimize the amount of the optional secondary activator with respect to the amount of at least one blowing agent CBA. For example, the at least one secondary activator SA is used in an amount of 10 to 80% by weight, more preferably 12 to 65% by weight, even more preferably 15 to 55% by weight, and still more preferably 20 to 45% by weight, based on the weight of the at least one chemical blowing agent CBA contained in the heat-expandable composition.

[0098] In one or more embodiments, the heat-expandable composition includes at least one secondary activator SA selected from the group consisting of: zinc oxide, zinc acetate, zinc stearate, zinc bis(p-toluenesulfinate), zinc bis(benzenesulfinate), and fatty acids having at least 6 carbon atoms.

[0099] In one or more embodiments, the heat-expandable composition includes at least one first secondary activator SA1 selected from the group consisting of 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 the group consisting of fatty acids having at least 6 carbon atoms, preferably stearic acid.

[0100] In one or more embodiments, the heat-expandable composition further includes at least one polyfunctional acrylate having at least 2, preferably between 2 and 6, acrylate functional values, and at least one crosslinking aid CA having a molecular weight of preferably less than 2500 g / mol, more preferably less than 1000 g / mol.

[0101] Such polyfunctional acrylates can improve the crosslinkability of the polymers contained in the heat-expandable composition and help obtain a stable foam structure. If the at least one crosslinking aid CA is used, it is preferably present in the heat-expandable composition in an amount of 0.05 to 5.0 wt%, more preferably 0.1 to 3.5 wt%, even more preferably 0.25 to 3.0 wt%, still more preferably 0.35 to 2.0 wt%, based on the total weight of the heat-expandable composition.

[0102] Suitable polyfunctional acrylates having two functional groups and used as at least one crosslinking aid CA include, for example, the following: 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 having two functional groups is hexanediol diacrylate.

[0103] Suitable polyfunctional acrylates having three or more functional groups and used as at least one crosslinking aid CA include, for example, the following: glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetraacrylate, di - (trimethylolpropane) tetraacrylate, pentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tri(2 - methacryloxyethyl) trimellitate, tri(2 - acryloxyethyl) isocyanurate, and further their ethoxylated or propoxylated derivatives. The most preferred polyfunctional acrylate having five functional groups is dipentaerythritol pentaacrylate. More preferred are highly functional hyperbranched acrylates having between 6 and 16 or more functional groups. Such acrylates include hyperbranched polyester - polyacrylates.

[0104] In one or more embodiments, if at least one free radical polymerization initiator I and at least one crosslinking aid CA are present in the thermally expandable composition, the total amount thereof accounts for 0.25 to 7.5% by weight, preferably 0.25 to 5.0% by weight, more preferably 0.5 to 3.5% by weight, and even more preferably 0.75 to 2.5% by weight of the total weight of the thermally expandable composition.

[0105] In one or more embodiments, the thermally expandable composition further contains at least one thermoplastic polymer TP.

[0106] Basically, all thermoplastic polymers and thermoplastic elastomers (TPE) are suitable for use as at least one thermoplastic polymer TP. Needless to say, the at least one thermoplastic polymer TP is different from the aforementioned at least one polymer P and at least one epoxy-functional polymer EP.

[0107] Examples of polymers suitable for use as at least one thermoplastic polymer TP include, for example, the following: styrene-butadiene copolymer, styrene-isoprene copolymer, ethylene-vinyl acetate copolymer (EVA), olefin-(meth)acrylate copolymer, olefin-(meth)acrylic acid alkyl copolymer, olefin (meth)acrylic acid copolymer, polyolefin, and halogenated polyolefin such as polyvinyl chloride (PVC). Particularly suitable olefin-(meth)acrylate copolymers and olefin-(meth)acrylic acid alkyl copolymers include, for example, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate copolymer (EBA), and ethylene-2-ethylhexyl acrylate copolymer.

[0108] Suitable thermoplastic polymers TP may contain unsaturated olefinic bonds, and they may further contain functional groups other than epoxy groups, such as halogen, nitrile, thiol, hydroxyl, or carboxyl groups. However, it is preferred that at least one of the thermoplastic polymers TP does not contain functional groups that may interfere with the curing mechanism of the thermally expandable composition. This approach allows for better control of the curing mechanism and secondary properties such as adhesion.

[0109] In one or more embodiments, at least one of the thermoplastic polymers TP is preferably a non-functionalized thermoplastic polymer selected from the group consisting of polyethylene, ethylene-α-olefin copolymer, polypropylene, propylene-α-olefin copolymer, ethylene-vinyl acetate copolymer, olefin-(meth)acrylate copolymer, olefin-(meth)acrylic acid alkyl copolymer, and olefin-(meth)acrylic acid copolymer, more preferably from the group consisting of ethylene-vinyl acetate copolymer, olefin-(meth)acrylate copolymer, and olefin-(meth)acrylic acid alkyl copolymer.

[0110] In one or more embodiments, at least one of the thermoplastic polymers TP - has a melt flow index determined according to ISO 1133 (190 °C / 2.16 kg) of 250 g / 10 min or less, preferably 200 g / 10 min or less, more preferably 175 g / 10 min or less, and / or - has a melting temperature (T m ) determined by DSC measurement method carried out according to ISO 11357-3 in the range of 150 °C or less, preferably 125 °C or less, more preferably 100 °C or less. has.

[0111] In one or more embodiments, at least one of the thermoplastic polymers TP includes 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, where the at least one first and second non-functionalized thermoplastic polymers (TP1 and TP2) are preferably selected from the group consisting of ethylene-vinyl acetate copolymers, olefin-(meth)acrylate copolymers, olefin-(meth)acrylic acid alkyl copolymers, and olefin-(meth)acrylic acid copolymers, more preferably selected from the group consisting of ethylene-vinyl acetate copolymers, olefin-(meth)acrylate copolymers, and olefin-(meth)acrylic acid alkyl copolymers.

[0112] In one or more embodiments, at least one of the first non-functionalized thermoplastic polymers TP1 has a melt flow index determined 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, particularly 25 - 200 g / 10 min, preferably 30 - 175 g / 10 min, and / or at least one of the second non-functionalized thermoplastic polymers TP2 has a melt flow index determined according to ISO 1133 (190 °C / 2.16 kg) of 25 g / 10 min or less, more preferably 15 g / 10 min or less, even more preferably 10 g / 10 min or less, particularly 1 - 10 g / 10 min, preferably 1 - 7.5 g / 10 min.

[0113] In one or more embodiments, the weight ratio of at least one of the first non-functionalized thermoplastic polymers TP1 to at least one of the second non-functionalized thermoplastic polymers TP2 ranges from (5:1) to (1:3), preferably from (3:1) to (1:2), more preferably from (2.5:1) to (1:1).

[0114] In one or more embodiments, at least one thermoplastic polymer TP is composed of at least one first non-functionalized thermoplastic polymer TP1 and at least one second non-functionalized thermoplastic polymer TP2, where at least one of the first and second non-functionalized thermoplastic polymers (TP1 and TP2) is preferably selected from the group consisting of ethylene-vinyl acetate copolymers, olefin-(meth)acrylate copolymers, olefin-(meth)acrylic acid alkyl copolymers, and olefin-(meth)acrylic acid copolymers, more preferably selected from the group consisting of ethylene-vinyl acetate copolymers, olefin-(meth)acrylate copolymers, and olefin-(meth)acrylic acid alkyl copolymers.

[0115] In one or more embodiments, the total amount of at least one polymer P and at least one thermoplastic polymer TP accounts for 25 to 80% by weight, preferably 30 to 75% by weight, more preferably 35 to 70% by weight, even more preferably 40 to 65% by weight, still more preferably 40 to 60% by weight of the total weight of the expandable composition upon heating.

[0116] Apart from the essential and optional components described above, the expandable composition upon heating may contain other compounds that are commonly used in such compositions and are known to those skilled in the art. Such examples include tackifying resins, fillers, colorants, dispersion aids, or homogenizing agents, stabilizers, and the like.

[0117] The term "tackifying resin" as used herein generally refers to a resin that improves the adhesiveness and / or tackiness of the composition. The term "tackiness" as used herein refers to the property of sticking or adhering simply by contact, which can be measured, for example, as loop tack. Preferred tackifying resins have tackiness at a temperature of 25°C. Such tackifying resins provide good adhesiveness to metal substrates, particularly metal substrates with oil adhesion, both before and after foaming the expandable composition.

[0118] The tackifying resins suitable for use in the heat-expandable composition have a relatively low average molecular weight (M n ), for example, 5000 g / mol or less, particularly 3500 g / mol or less, preferably 2500 g / mol or less, and a softening point measured 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. Particularly suitable tackifying resins include synthetic resins, natural resins, and chemically modified natural resins.

[0119] The term "synthetic resin" as used herein refers to a compound obtained by a controlled chemical reaction, such as polyaddition or polycondensation, between well-defined reactants that do not themselves have resinous properties. Monomers that can be polymerized to synthesize synthetic resins include aliphatic monomers, alicyclic monomers, aromatic monomers, or mixtures thereof. Suitable aliphatic monomers include paraffins, olefins, and conjugated diolefins of C4, C5, and C6. Examples of aliphatic monomers or alicyclic monomers include the following: 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 the following: styrene, alpha-methylstyrene, vinyltoluene, methoxystyrene, tertiary-butylstyrene, chlorostyrene, coumarone, and indene monomers (including indene and methylindene), and combinations thereof.

[0120] Suitable synthetic resins include, for example, the following: hydrocarbon resins, coumarone-indene resins, polyindene resins, polystyrene resins, vinyltoluene-alpha methylstyrene copolymer resins, and alpha methylstyrene resins.

[0121] In the present disclosure, the term "hydrocarbon resin" refers to a synthetic resin produced by polymerizing a mixture of unsaturated monomers obtained from petroleum-based raw materials such as natural liquefied gas, gas oil, or by-products of the cracking of petroleum naphtha. These types of hydrocarbon resins are also known as "petroleum resins" or "petroleum hydrocarbon resins". They further include pure monomer aromatic resins, which are prepared by polymerizing aromatic monomer raw materials that have been pre-purified to remove contaminants that cause coloring and to accurately adjust the composition of the product.

[0122] Suitable hydrocarbon resins are commercially available, for example, under the following names: Wingtack® (registered trademark), Wingtack® Plus, Wingtack® Extra, and Wingtack® STS (all manufactured by Cray Valley); Escorez® (registered trademark) 1000 series, Escorez® (registered trademark) 2000 series, and Escorez® (registered trademark) 5000 series (all manufactured by ExxonMobil Chemical); Novares® (registered trademark) T series, Novares® (registered trademark) TT series, Novares® (registered trademark) TD series, Novares® (registered trademark) TL series, Novares® (registered trademark) TN series, Novares® (registered trademark) TK series, and Novares® (registered trademark) TV series (all manufactured by RUETGERS Novares GmbH); and Kristalex® (registered trademark), Plastolyn® (registered trademark), Piccotex® (registered trademark), Piccolastic® (registered trademark), and Endex® (registered trademark) (all manufactured by Eastman Chemicals).

[0123] If an adhesion - imparting resin is used, it is preferably contained in the heat - expandable composition in an amount of 2 to 25% by weight, preferably 4 to 20% by weight, more preferably 5 to 15% by weight, based on the total weight of the heat - expandable composition.

[0124] Examples of fillers suitable for use in the heat - expandable composition include, for example, the following: ground or precipitated calcium carbonate, lime, calcium carbonate - magnesium, talcum, gypsum, graphite, barite, pyrogenic or precipitated silica, silicate, mica, wollastonite, kaolin, feldspar, chlorite, bentonite, montmorillonite, dolomite, quartz, cristobalite, calcium oxide, aluminum hydroxide, magnesium oxide, hollow ceramic spheres, hollow glass spheres, hollow organic spheres, glass spheres, functionalized alkoxanes, and carbon black. Suitable fillers include commercially available forms of the fillers listed above, both with and without an organic coating. Particularly suitable fillers include the following: ground or precipitated calcium carbonate, calcium carbonate - magnesium, talcum, gypsum, graphite, barite, pyrogenic or precipitated silica, silicate, mica, wollastonite, carbon black, and mixtures thereof.

[0125] If fillers are used, they are preferably incorporated into the heat - expandable composition in an amount of 1 to 20% by weight, more preferably 1 to 15% by weight, even more preferably 2.5 to 15% by weight, based on the total weight of the heat - expandable composition.

[0126] It is also possible to add a colorant or a dye, for example, a pigment based on carbon black, to the heat - expandable composition. Their amounts are preferably between 0.1 and 1% by weight, based on the total weight of the heat - expandable composition.

[0127] It is preferred that the volume increase of the heat-expandable composition after curing is at least 100%, preferably at least 150%, more preferably at least 250% compared to the uncured composition. Here, the volume increase is measured in combination with the mass of the sample determined by a precision balance using the density measurement (Archimedes' principle) in deionized water according to the DIN EN ISO 1183 method.

[0128] In one or more embodiments, the heat-expandable composition after curing has a volume increase in the range of 100 to 3000%, preferably 150 to 2500%, more preferably 250 to 2000%, even more preferably 250 to 2000% compared to the uncured composition.

[0129] The heat-expandable composition in the present invention can be produced by mixing the components in various suitable mixing devices such as a dispersion mixer, a planetary mixer such as a planetary roller, an extruder such as a twin-screw extruder, a kneader such as a Buss, Banbury or roller kneader, or a two-roll mill.

[0130] In order to make it possible to easily process the components into a homogeneously mixed mixture by reducing the viscosity and / or melting the individual components, it would be advantageous to heat the components before or during mixing by applying an external heat source or by the frictional heat generated by the mixing process itself. However, care must be taken, for example, to monitor the temperature and, if appropriate, use a cooling device so as not to exceed the activation temperature of at least one chemical blowing agent CBA and at least one free radical polymerization initiator I. It is preferred that the heat-expandable composition thus obtained is substantially solid at normal room temperature (23°C), which means that it does not undergo visible deformation under the action of gravity for at least 24 hours at this temperature.

[0131] After mixing the components of the heat-expandable composition, the composition thus obtained can be shaped into a desired shape using, for example, extrusion molding, blow molding, pelletization, injection molding, compression molding, punching, or die pressing, or other suitable processing methods.

[0132] The heat-expandable composition of the present invention can be produced in a substantially one-step process, including adding all the components in sequence or simultaneously. However, it can also be advantageous to obtain the heat-expandable composition as a two-component system or even a multi-component system. In these cases, the components of the heat-expandable composition are supplied in separate air- and moisture-impermeable packages or in multiple compartments within a single package, and are mixed with each other or, in some cases, with other compounds during or immediately before use of the heat-expandable composition. Such an approach can be employed, for example, to extend the shelf life of the heat-expandable composition in locations with severe conditions (such as extremely high temperatures), to optimize storage conditions and transport weight, or to provide modular-type compositions for custom orders for different applications.

[0133] The heat-expandable composition according to the present invention has storage stability under normal storage conditions. The term "storage stability" in this disclosure refers to a substance that can be stored without causing any significant change in the properties related to the use of the substance under specific storage conditions for a long period, for example, at least one month, particularly at least three months. The term "typical storage conditions" in this case refers to a temperature of 60°C or lower, particularly 50°C or lower.

[0134] The expansion of the thermally expandable composition of the present invention is initiated by heating. This means that the thermally expandable composition is activated by a heating step that exceeds its activation temperature, and the decomposition of at least one of its chemical blowing agents CBA (as a result, gas is generated), and the expandable material exhibits a sufficiently long duration for it to expand and harden into its intended final (fully expanded and stable) state. The optimal temperature and duration (residence time) of the heating step depend on the embodiment of the thermally expandable composition, particularly on the composition of at least one chemical blowing agent CBA and at least one free radical polymerization initiator I contained in the thermally expandable composition. The thermally expandable composition preferably has an activation temperature in the range of 120 to 250 °C, more preferably 140 to 220 °C, and a residence time for the heating step in the range of 5 to 90 minutes, more preferably 10 to 60 minutes.

[0135] Regarding at least one polymer P, at least one epoxy-functional polymer EP, at least one thermoplastic polymer TP, at least one chemical blowing agent CBA, at least one free radical polymerization initiator I, at least one activator A, and at least one crosslinking aid CA, what was stated as preferred above applies equally to all aspects of the present invention, unless otherwise specified.

[0136] Another aspect of the present invention is a shielding element (baffle) and / or a reinforcing element for a hollow structure, which contains or consists essentially of the thermally expandable composition of the present invention.

[0137] Such components are used to seal, shield, and / or reinforce cavities in hollow structures, such as hollow structural parts of automobiles. Examples of hollow parts in vehicles include: body components (e.g., panels), frame components (e.g., tubes by the hydroforming method), pillar structures (e.g., A, B, C, or D-pillars), bumpers, roofs, etc.

[0138] In one or more embodiments, the shielding and / or reinforcing components for the hollow structure consist essentially of the thermally expandable composition of the present invention. In these embodiments, it is advantageous to provide components having a shape that can be easily incorporated or attached to the wall surface of the hollow structure to be shielded and / or reinforced. Components having such a shape can be obtained from the thermally expandable composition, for example, by injection molding, punching or die pressing, or extrusion using a mold.

[0139] In one or more further embodiments, the shielding and / or reinforcing components further include a support on which the thermally expandable composition is deposited or attached. Such a design is more economical and, for example, by incorporating pins, bolts, or hooks onto the support component, the shielding and / or reinforcing components can be easily fixed onto the wall surface of the structure to be shielded and / or reinforced. Furthermore, by appropriately designing the support component, the mechanical performance and stability of the shielding and / or reinforcing components can be improved.

[0140] If a support for shielding and / or reinforcing components is used, it may be made of any material that can be processed and shaped. Suitable materials for the support include polymer materials such as plastics, elastomers, thermoplastics, blends thereof, etc. Preferred thermoplastic materials include, but are not limited to, the following: polymers such as polyurethane, polyamide, polyester, polyolefin, polysulfone, polyethylene terephthalate (PET), polyvinyl chloride (PVC), chlorinated polyolefin, etc. Particularly preferred are polymers stable at high temperatures such as poly(phenyl ether), polysulfone, polyethersulfone, polyamide, especially polyamide 6, polyamide 6,6, polyamide 11, polyamide 12, and mixtures thereof. Other suitable materials for the support include the following: metals, especially aluminum or steel, or naturally occurring organic substances such as wood or other (pressure-processed) fibrous substances. Glassy or ceramic substances can also be used. It is also possible to use such substances in combination. It is also conceivable to fill or mold such substances using, for example, fibers, minerals, clay, silicates, carbonates, combinations thereof, etc.

[0141] The components of the support can further exhibit any shape or dimension. It can further be composed of several non-directly connected parts. For example, it can be solid, hollow, or foamed, or it can exhibit a grid-like structure. The surface of the components of the support can typically be smooth, rough, or structured depending on the intended use of the shielding and / or reinforcing components.

[0142] Another subject of the present invention is a process for manufacturing the shielding and / or reinforcing components of the present invention, where the thermally expandable composition is injection molded onto the support or co-extruded with the support.

[0143] The details of the manufacturing process of the shielding and / or reinforcing components of the present invention strongly depend on the material of the support. When the material of the support can be (injection) molded or extruded, the shielding and / or reinforcing components can be manufactured by a two-step injection molding process or by co-extrusion of the support and the thermally expandable composition.

[0144] In the case of the two-step injection molding process, the first step includes injecting the material of the support into the mold. After solidification, the cavity of the injection molding mold is enlarged or adjusted, or the injection molded piece is transferred into another mold, and then the second step including injecting the thermally expandable composition is carried out.

[0145] For example, if the support cannot be injection molded or extruded because the support is made of metal or alloy, the support is first manufactured by an appropriate process and then introduced into the injection molding mold. Then, it is preferable to injection mold the thermally expandable composition into the mold in which the support has been pre-inserted. Another possibility is that the thermally expandable composition may be extruded onto the pre-manufactured support component. Needless to say, there is also the possibility of separately manufacturing the support and the component of the thermally expandable composition by various appropriate processes and then attaching the component of the thermally expandable composition to the support by various appropriate means, such as chemically or physically, for example, by an adhesion method, or mechanically, for example, by bolting or screwing.

[0146] Another subject of the present invention is the use of at least one compound having a silane group of formula (I) for improving the wet storage resistance of a thermally expandable material containing components a) to c) and optionally d) of the thermally expandable composition of the present invention.

[0147] The expression "use of at least one compound for improving the wet storage resistance of a heat-expandable material" is to be understood as meaning that, as a result of adding the at least one compound to the heat-expandable material, the expansion loss of the heat-expandable material resulting from storage under high-temperature and high-humidity conditions is suppressed.

[0148] In one or more embodiments, the at least one compound having a silane group of formula (I) is selected from the group consisting of silane-functionalized polymers comprising a silane group of formula (I) and an alkoxysilane of formula (II), wherein the silane-functionalized polymer comprising the silane group of formula (I) is preferably selected from the group consisting of ethylene-vinyl acetate copolymers grafted with silane, olefin-silane copolymers, and olefin-(meth)acrylate alkyl-silane terpolymers.

[0149] In one or more embodiments, the at least one compound comprising a silane group of formula (I) is added to the heat-expandable material in an amount such that the heat-expandable material contains from 0.05 to 10.0% by weight, preferably from 0.15 to 7.5% by weight, more preferably from 0.20 to 5.0% by weight, and even more preferably from 0.25 to 3.5% by weight of the silane group of formula (I), based on the total weight of the heat-expandable material.

[0150] Another subject of the present invention is the use of the shielding and / or reinforcing components of the present invention for sealing, shielding, or reinforcing cavities or hollow structures of land vehicles, ships, or aircraft, preferably motor vehicle vehicles, and / or cavities of buildings, in order to reduce the transmission of noise, vibration, moisture, and / or heat, and / or to mechanically strengthen the structure surrounding the cavity or hollow structure.

[0151] Yet another subject of the present invention is a method for sealing, shielding, and / or reinforcing a cavity or a hollow structure, wherein a component containing a heat-expandable composition according to the present invention is introduced into the cavity or the hollow structure, and then expanded by heat and / or UV treatment, whereby the cavity or the hollow structure is at least partially filled with the expanded composition.

[0152] The temperature of the thermal expansion step is preferably 140 to 250 °C, more preferably 150 to 220 °C, and even more preferably 150 to 200 °C. The suitable time for the thermal expansion step, i.e., the preferred baking time of the heat-expandable composition, is 5 to 90 minutes, more preferably 10 to 60 minutes, and even more preferably 10 to 30 minutes.

[0153] When used in the manufacture of motor vehicles, with regard to the heat activation of the component containing the heat-expandable composition, it is advantageous to combine the heat activation with another process step including heat treatment. An example of such a process step is electrocoating (cathodic dip coating / coating) of the vehicle body chassis.

Examples

[0154] The following chemicals listed in Table 1 were used in the formulation of the heat-expandable composition.

[0155]

Table 1

[0156] Preparation of Heat-Expandable Composition A heat-expandable composition containing the components shown in Tables 3 and 4 was prepared using a Brabender mixer while adjusting the temperature. In the preparation process, first, the polymer component was mixed at a temperature of 110 to 115 °C until a homogeneous mixture was obtained. Then the system was cooled to a temperature lower than the activation temperature (80 to 90 °C) of the heat-reactive raw material substances. Next, the heat-reactive raw material substances (free radical polymerization initiator, foaming agent) were incorporated into the system until a homogeneous mixture was obtained. Then, the substance thus obtained was hot-pressed and used as a test sample in a volume expansion test.

[0157] In the case of the reference example composition Ref-2 and the example compositions Ex-1 to Ex-5, premixes 1 to 6 containing the components shown in Table 2 were used to prepare their heat-expandable compositions. These premixes were prepared using the following procedure. Polymers TP1 and TP2 were first mixed using a Brabender mixer at a temperature of 100 °C for 3 minutes. Then, alkoxysilane SI and / or free radical polymerization initiator I1 (organic peroxide) were added and mixing was continued at the same temperature for 10 minutes. In the final step, the temperature was raised to 160 °C and mixing was continued for an additional 15 minutes. The premixes used to prepare the example compositions Ex-1 to Ex-5 are considered to contain a mixture of ethylene-vinyl acetate copolymers grafted with two different silanes.

[0158] Volume Expansion and Expansion Loss after Storage in Wet State The expansion performance of the compositions of the reference examples and examples was tested by heat-treating (baking) the prepared test samples in an oven at a temperature of 140 to 200 °C for 10 minutes. The heating time from room temperature (23 °C) to each baking temperature was 20 minutes (for both 140 °C and 200 °C). The temperature and the magnitude of expansion at the corresponding baking temperature (in % units based on the original volume before expansion) are shown in Tables 3 and 4.

[0159] The volume expansion ratio was determined by measuring the density of the tested samples before and after expansion. The density was determined using the water immersion method (Archimedes' principle) in deionized water in accordance with DIN EN ISO 1183, and a precision balance was used for mass measurement.

[0160] The expansion performance was tested before ("initial") and after the wet storage treatment. In the wet storage treatment, the samples were stored at 100% relative humidity and 40 °C for 7 days before firing. The "expansion loss" (unit: %) representing the moisture resistance of the tested heat-expandable composition was calculated according to the following formula: [Number] [where Exp i is the initial expansion obtained with the test composition before the wet storage treatment, and Exp h is the expansion obtained after the wet storage treatment]

[0161] [Table 2]

[0162] [Table 3]

[0163] [Table 4] The present disclosure includes the following aspects of the invention: <Aspect 1> A heat-expandable composition comprising: (a) at least one polymer P, (b) at least one free radical polymerization initiator I, and (c) at least one chemical blowing agent CBA, and (d) optionally, at least one epoxy-functional polymer EP, wherein the composition contains a silane group of the following formula (I): Heat-expandable composition: [Chemistry] [In the formula, R 1 represents an alkyl group having 1 to 8 carbon atoms, preferably 1 to 5 carbon atoms, 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]. <Aspect 2> The heat-expandable composition according to Aspect 1, containing 0.05 to 10.0% by weight, preferably 0.15 to 7.5% by weight, of the silane group of the formula (I) based on the total weight of the heat-expandable composition. <Aspect 3> The heat-expandable composition according to Aspect 1 or 2, wherein at least a part of the silane group of the formula (I) is bonded to the at least one polymer P, and / or the composition further contains at least one alkoxysilane SI of the following formula (II):

Chem.

Chem.

Claims

Claim 1: A baffle and / or reinforcing component for a hollow structure, comprising a thermally expandable composition, wherein the thermally expandable composition comprises: (a) at least one polymer P, (b) at least one free radical polymerization initiator I, and (c) at least one chemical blowing agent CBA, and (d) optionally, at least one epoxy-functional polymer EP, wherein the composition comprises a silane group of the following formula (I), at least a part of the silane groups of the formula (I) is bonded to the at least one polymer P, the at least one polymer P is a silane-functionalized polymer containing a silane group of the formula (I), Baffle and / or reinforcing component: 【Chemical 1】 [wherein, 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 index a has a value of 0, 1, or 2]. Claim 2: The baffle and / or reinforcing component according to claim 1, wherein the thermally expandable composition comprises 0.05 to 10.0% by weight of the silane group of the formula (I) based on the total weight of the thermally expandable composition. Claim 3: The baffle and / or reinforcing component according to claim 1 or 2, wherein the composition further comprises at least one alkoxysilane SI of the following formula (II): [Chemical 2] [wherein, R １ and R ２ are as defined in claim 1 or 2 and R ３ represents a linear, branched, or cyclic alkenyl group having 1 to 20 carbon atoms. Claim 4 The at least one alkoxysilane SI of the formula (II) is selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyl-tris(2-methoxyethoxy)silane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, vinyldimethylmethoxysilane, and vinylmethyldibutoxysilane. The baffle and / or reinforcing component according to claim 3. Claim 5 The baffle and / or reinforcing component according to any one of claims 1 to 4, wherein the at least one polymer P is a polymer functionalized with an organosilane containing a silane group of the formula (I). Claim 6 The baffle and / or reinforcing component according to any one of claims 1 to 5, wherein the at least one polymer P is selected from the group consisting of ethylene-vinyl acetate copolymer grafted with silane, olefin-silane copolymer, and olefin-(meth)acrylate alkyl-silane terpolymer. Claim 7 The baffle and / or reinforcing component according to any one of claims 1 to 6, wherein the at least one free radical polymerization initiator I is a peroxide polymerization initiator PI. **Claim 8**: The baffle and / or reinforcing component according to any one of claims 1 to 7, wherein the thermally expandable composition further comprises at least one epoxy-functional polymer EP, and the at least one epoxy-functional polymer EP accounts for 5 to 30% by weight of the total weight of the thermally expandable composition. **Claim 9**: The baffle and / or reinforcing component according to any one of claims 1 to 8, wherein the thermally expandable composition further comprises at least one activator A comprising at least one compound of the following formula (III): 【Chemical Formula 3】 [wherein, R ４ and R ５ each independently represents a hydrogen atom or, optionally, a monovalent alkyl group having 1 to 10 carbon atoms which further optionally contains an oxygen atom, a nitrogen atom, and / or an aromatic moiety, or R ４ and R ５ together form a divalent alkyl group having 1 to 10 carbon atoms which further optionally contains an oxygen atom, a nitrogen atom, and / or an aromatic moiety; R ６ and R ７ each independently represents a hydrogen atom or, optionally, a monovalent alkyl group having 1 to 10 carbon atoms which may further contain an oxygen atom or a nitrogen atom; and the index n has a value of 1 or 2]. **Claim 10**: The baffle and / or reinforcing component according to any one of claims 1 to 9, wherein the thermally expandable composition further comprises at least one crosslinking aid CA comprising at least one polyfunctional acrylate having at least two acrylate functional values. **Claim 11** Use of a compound having at least one silane group of formula (I) according to claim 1 for improving the wet storage resistance of a thermally expandable material comprising components (a) to (d) of the thermally expandable composition as defined in any one of claims 1 to 10. **Claim 12** A baffle and / or reinforcing element according to claim 1, further comprising a support, wherein the thermally expandable composition is deposited or adhered onto the support. **Claim 13** A method for manufacturing the baffle and / or reinforcing element according to claim 12, comprising injection molding the thermally expandable composition onto the support or co-extrusion molding with the support. **Claim 14** Use of the baffle and / or reinforcing element according to any one of claims 1 to 10 or 12 for sealing, buffering, or reinforcing a cavity or hollow structure of a land vehicle, ship, or aircraft, and / or a cavity of a building, to reduce the transmission of noise, vibration, moisture, and / or heat, and / or to mechanically strengthen the structure surrounding the cavity. **Claim 15** A method for sealing, buffering, and / or reinforcing a cavity or hollow structure, comprising introducing a component containing the heat-expandable composition according to any one of claims 1 to 10 into the cavity or hollow structure, and then expanding it by heating, whereby the cavity or hollow structure is at least partially filled with the expanded composition.

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