A heat-expandable composition having suppressed odor emission.

Abstract

The present invention aims to provide a heat-expandable composition comprising at least one solid rubber, at least one tackifying resin, azodicarbonamide, zinc oxide, and at least one metal salt AMS of a fatty acid containing 16 or 18 carbon atoms (wherein the metal is zinc, preferably the metal salt AMS of the fatty acid is zinc stearate). The present invention further aims to provide a method for sealing and / or shielding a shielding component, cavity or hollow structure portion comprising the heat-expandable composition, and the use of azodicarbonamide, zinc oxide, and the metal salt AMS of at least one fatty acid in the heat-expandable composition to suppress odor generation after heating the heat-expandable composition.

Description

[Technical Field] 【0001】 The present invention relates to heat-expandable compositions and their use for obtaining baffle elements. Such elements are particularly suitable for use in sealing and / or baffling cavities in hollow structures, such as the hollow structural parts of automobile vehicles. [Background technology] 【0002】 Manufactured articles often contain openings (orifices), cavities, or other hollow parts that arise from the manufacturing process and / or are designed into the product for various purposes, such as weight reduction. Automotive vehicles contain several such openings and cavities throughout the vehicle, including, for example, within the structural pillars of the vehicle and within the siding of the vehicle doors. It is often desirable to seal such openings and cavities by means of sealing members incorporated within them, in order to minimize the transfer of noise, vibration, smoke, dust, water, moisture, etc., from one area to another within the vehicle. 【0003】 Components used for sealing or shielding often consist of a carrier made of plastic, metal, or other rigid material, and one or more layers of thermoplastic material bonded thereto that can expand when heat or other physical or chemical energy is applied, although they may also be made entirely of expandable material. If appropriate design is used, it is possible not only to insert the shielding components into the hollow portions of the structure during the manufacturing process, but also to leave the inner walls of the structure as a structure (or passable cavity) that remains accessible, for example, by a liquid. For example, during the manufacturing process of a vehicle, most of the hollow portions of a metal frame may be covered with an electrodeposition coating ("e-coat") liquid while the shielding components are still inserted, and then, during a heat treatment step, the expandable thermoplastic material of the shielding components expands and fills the cavity as intended. 【0004】 Currently employed heat-expandable compositions used to provide shielding components often contain elastomeric or thermoplastic polymer matrices, which can be crosslinked using a suitable curing agent and one or more blowing agents. The most widely used chemical blowing agents in heat-expandable compositions include azodicarbonamide (also known as azodicarbonboxamide or azobisformamide) and 4,4-oxydibenzenesulfonyl hydrazide (abbreviated as OBSH). Under activation conditions, such as high temperatures, curing of the crosslinkable network occurs simultaneously with the decomposition of the blowing agent, releasing gas. This results in the volume expansion described above, forming a stable foam. An example of such a system is disclosed in German Patent Application Publication No. 10 2011 080 223A1. [Overview of the project] [Problems that the invention aims to solve] 【0005】 One of the problems associated with the established solutions mentioned above is that heat-expandable compositions using azodicarbonamide as a foaming agent may have the drawback of emitting an odor, because azodicarbonamide becomes a potential source of ammonia when exposed to high temperatures. In the automotive industry in particular, many manufacturers rely on the VDA 270 test method to measure the odor of the substances they use, and there is a demand for low-odor substances. 【0006】 Therefore, it is desirable to obtain a heat-expandable composition containing azodicarbonamide as a blowing agent that is not affected by those limitations and in which odor generation during or after the foaming process is suppressed. [Means for solving the problem] 【0007】 The object of the present invention is to provide a heat-expandable composition that is not affected by those limitations and in which odor generation during or after the foaming process is suppressed. 【0008】 Surprisingly, the present invention provides a solution to the problem by providing a heat-expandable composition as defined in claim 1. 【0009】 The compositions according to the present invention are particularly suitable for use in sealing or shielding components, for example, in automotive applications. Further aspects of the present invention are the subject of other independent claims. Preferred embodiments of the present invention are the subject of dependent claims. [Modes for carrying out the invention] 【0010】 The subject of this invention is a heat-expandable composition comprising the following: a) At least one type of solid rubber R, b) At least one type of tackifying resin TR, c) Azodicarbonamide ADCA, d) Zinc oxide (ZnO), e) A metal salt AMS of at least one fatty acid containing 16 or 18 carbon atoms (where the metal is zinc, preferably the metal salt AMS of the fatty acid is zinc stearate). 【0011】 The weight ratio of azodicarbonamide ADCA to zinc oxide ZnO (ADCA / ZnO) is 2.0 to 7.5. 【0012】 The weight ratio of azodicarbonamide ADCA to the metal salt AMS of fatty acids (ADCA / AMS) is 0.75 to 6.5. 【0013】 Substance names beginning with "poly" formally refer to substances that contain two or more of the functional groups indicated in their name per molecule. For example, polyols refer to compounds having at least two hydroxyl groups, and polyethers refer to compounds having at least two ether groups. 【0014】 The term "polymer" refers to a group of chemically homogeneous macromolecules produced by polymerization reactions (polymerization, polyaddition, polycondensation), where these macromolecules differ in degree of polymerization, molecular weight, and chain length. This term also includes derivatives of the aforementioned generic macromolecules obtained as a result of polymerization reactions, i.e., compounds obtained, for example, by addition or substitution reactions of functional groups in predetermined macromolecules, which may be chemically homogeneous or chemically heterogeneous. 【0015】 The term "rubber" refers to natural, synthetic, or modified high molecular weight polymers or combinations of polymers that are capable of recovering from large deformations, i.e., are elastic. Typical rubber can be stretched or deformed to at least 200% of its original dimensions under externally applied force, and after the external force is removed, it will return to substantially its original dimensions, leaving only a small permanent strain (typically less than about 20%). Specifically, the term "rubber" refers to rubber that is not chemically crosslinked. The term "chemically crosslinked" should be understood as meaning that the polymer chains forming the elastomer are linked to each other by multiple covalent bonds and are mechanically and thermally stable. 【0016】 The term "molecular weight" refers to the molar mass (g / mol) of a molecule or a part of a molecule (also called a "residue"). The term "average molecular weight" refers to the number-average molecular weight (M) of an oligomeric or polymeric mixture of molecules or residues. n This refers to [a specific molecule]. The molecular weight can be determined by gel permeation chromatography. 【0017】 "Glass transition temperature" (T g The term "glass transition temperature (T)" refers to the temperature at which, above which the polymer components become soft and flexible, and below which they become hard and glassy. g It is preferable to measure this as the peak of the loss modulus (G") curve measured by dynamic mechanical analysis (DMA) with a frequency of 1 Hz and a strain of 0.1%. 【0018】 The term "softening point" refers to the temperature at which a compound softens and becomes rubbery, or the temperature at which the crystalline portion of the compound melts. The softening point can be determined by the ring and ball measurement method, which is performed according to the DIN EN 1238:2011 standard. 【0019】 The term "room temperature" refers to a temperature of 23°C. 【0020】 The heat-expandable composition further contains at least one solid rubber R. The term "solid rubber" as used herein refers to a rubber that is solid at a temperature of 25°C. The amount of the solid rubber R in the heat-expandable composition is not subject to any particular restrictions. However, it is preferred that at least one solid rubber R be present in the heat-expandable composition in an amount of at least 1.5% by weight, more preferably at least 2.5% by weight, based on the total weight of the heat-expandable composition. 【0021】 In one or more embodiments, the at least one solid rubber R occupies 5 to 40% by weight, preferably 7.5 to 35% by weight, more preferably 15 to 25% by weight of the total weight of the heat-expandable composition. 【0022】 The at least one solid rubber R is preferably selected from the group consisting of: butyl rubber, halogenated butyl rubber, styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPR), ethylene-propylene-diene monomer rubber (EPDM), natural rubber, polychloroprene rubber, cis-1,4-polyisoprene, polybutadiene rubber, isoprene-butadiene rubber, styrene-isoprene-butadiene rubber, nitrile rubber, nitrile-butadiene rubber, and acrylonitrile rubber. 【0023】 In one or more embodiments, the at least one solid rubber R is selected from the group consisting of: butyl rubber, halogenated butyl rubber, styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPR), ethylene-propylene-diene monomer rubber (EPDM), natural rubber, cis-1,4-polyisoprene, and polybutadiene rubber. It is preferred that the solid rubber R be styrene-butadiene rubber (SBR). 【0024】 Preferably, at least one of the solid rubbers R has an average molecular weight (M) of at least 100,000 g / mol, more preferably at least 125,000 g / mol. n ), and / or having a Mooney viscosity (ML1+4, 100°C) of 150 MU or less, more preferably 125 MU or less, and even more preferably 100 MU or less. In the disclosure of the present invention, the term "Mooney viscosity" refers to a measure of the viscosity of rubber. It is defined as the shear torque resisting the rotation of a cylindrical metal disk (i.e., rotor) embedded in rubber within a cylindrical cavity. The dimensions of the shear disk viscometer, the test temperature, and the procedure for measuring Mooney viscosity are specified in the ASTM D1646-19a standard. 【0025】 In one or more embodiments, the at least one solid rubber R comprises at least one solid styrene-butadiene rubber R1. Generally, the expression "at least one component X comprises at least one component XN," for example, "at least one solid rubber R comprises at least one solid styrene-butadiene rubber R1," should be understood in the context of this disclosure to mean that the heat-expandable composition comprises one or more solid styrene-butadiene rubber R1 as representative of the at least one solid rubber R. 【0026】 Preferably, at least one of the solid styrene-butadiene rubbers R1 is an emulsion-polymerized styrene-butadiene rubber. These can be classified into two types, cold rubber and hot rubber, depending on the emulsion polymerization temperature, but hot rubber (hot type) is preferred. 【0027】 Preferably, at least one type of solid styrene-butadiene rubber R1 has the following properties: - Styrene content of 1 to 60% by weight, preferably 5 to 50% by weight, more preferably 10 to 40% by weight, even more preferably 15 to 40% by weight, and / or - Mooney viscosity in the range of 15 to 150 MU (Mooney units), preferably 20 to 100 MU, more preferably 20 to 80 MU, and even more preferably 25 to 60 MU (ML1+4, 100°C). 【0028】 Preferred solid styrene-butadiene rubber R1 includes, for example, pre-crosslinked styrene-butadiene elastomers commercially available from Petroflex / Lanxess as trade names Petroflex® SBR 1009A, 1009S, and 1018 elastomers, which are core-grated using either rosin or fatty acid soap as an emulsifier by the hydrochloric acid method, and Lion Elastomers' SBR 1009, 1009A, 1502, 1507, and 4503 elastomers, which are produced by hot emulsion polymerization using divinylbenzene. 【0029】 The heat-expandable composition further includes at least one tackifying resin TR. 【0030】 In this disclosure, the term "tackifying resin" generally refers to a resin that improves the adhesion and / or tackiness of a composition. In this specification, "tackiness" refers to the ability to adhere or bond simply by contact, which can be measured, for example, as loop tack. Preferred tackifying resins are tackiness at a temperature of 25°C. Such tackifying resins TR provide good adhesion to metal substrates, particularly oil-covered metal substrates, both before and after foaming of the heat-expandable composition. Tackifying resins typically have a relatively low average molecular weight (M), for example, 5,000 g / mol or less, particularly 3,500 g / mol or less, preferably 3,000 g / mol or less. n ) has. 【0031】 Preferably, at least one of the tackifying resins TR has the following properties: - Softening point measured by the ring-sphere method in accordance with DIN EN 1238:2011, in the range of 50 to 200°C, more preferably 65 to 175°C, even more preferably 70 to 165°C, and even more preferably 75 to 150°C, and / or - Average molecular weight (M) in the range of 150 to 5,000 g / mol, more preferably 250 to 3,500 g / mol, and even more preferably 350 to 2,500 g / mol n ), and / or - The glass transition temperature (T) is measured as the peak of the loss modulus (G") curve measured by dynamic mechanical measurement (DMA) using an applied frequency of 1 Hz and a strain level of 0.1%, and is defined as being 0°C or higher, preferably 15°C or higher, more preferably 25°C or higher, even more preferably 30°C or higher, and even more preferably 35°C or higher. g ). 【0032】 In one or more embodiments, at least one tackifying resin TR accounts for 12 to 20% by weight, preferably 4 to 12% by weight, and more preferably 6 to 10% by weight, of the total weight of the heat-expandable composition. 【0033】 Suitable resins for use as at least one type of tackifying resin TR include synthetic resins, natural resins, and chemically modified natural resins. 【0034】 Suitable examples of natural and chemically modified natural resins include rosin, rosin esters, phenol-modified rosin esters, and terpene resins. The term "rosin" should be understood to include gum rosin, wood rosin, tall oil rosin, distilled rosin, and modified rosin, such as those obtained by dimerizing, hydrogenating, maleating, and / or polymerizing these rosins. 【0035】 Rosin esters suitable for use as at least one tackifying resin TR can be obtained by reacting rosin with a polyhydric alcohol or polyol in the presence of an acid or base catalyst, for example, pentaerythritol, glycerol, dipentaerythritol, tripentaerythritol, trimethylolethane, trimethylolpropane, ethylene glycol, polyethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, trimethylene glycol, propylene glycol, neopentyl glycol. 【0036】 Suitable terpene resins for use as at least one type of tackifying resin TR include: copolymers and terpolymers of natural terpenes, such as styrene / terpene and alpha-methylstyrene / terpene resins; polyterpene resins, generally obtained by polymerization of terpene hydrocarbons at relatively low temperatures in the presence of a Friedel-Crafts catalyst, even bicyclic monoterpenes (known as pinene); hydrogenated polyterpene resins; and phenol-modified terpene resins (including their hydrogenated derivatives). 【0037】 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 reagents that do not possess resin properties on their own. Monomers that can be polymerized to synthesize synthetic resins include aliphatic monomers, alicyclic monomers, aromatic monomers, or mixtures thereof. Preferred aliphatic monomers include C4, C5, and C6 paraffins, olefins, and conjugated diolefins. Examples of aliphatic 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 are examples. Typical aromatic monomers include: styrene, alpha-methylstyrene, vinyltoluene, methoxystyrene, tertiary butylstyrene, chlorostyrene, coumarone, and indene monomers (including indene and methylindene), as well as combinations thereof. 【0038】 Suitable synthetic resins for use as at least one type of tackifying resin TR include, for example, hydrocarbon resins, coumarone-indene resins, polyindene resins, polystyrene resins, vinyltoluene-alphamethylstyrene copolymer resins, and alphamethylstyrene resins. 【0039】 The term "hydrocarbon resin" herein refers to synthetic resins produced by polymerizing mixtures of unsaturated monomers obtained from petroleum-based raw materials, such as natural liquefied gas, gas oil, or by-products of petroleum naphtha cracking. These types of synthetic hydrocarbon resins are also known as "petroleum resins" or "petroleum hydrocarbon resins." These hydrocarbon resins also include aromatic resins of pure monomers, which are prepared by polymerizing aromatic monomer raw materials that have been pre-purified to remove impurities that cause discoloration and to precisely control the composition of the product. 【0040】 Examples of suitable hydrocarbon resins to be used as at least one tackifying resin TR include: C5 aliphatic resins, mixed C5 / C9 aliphatic / aromatic resins, aromatically modified C5 aliphatic resins, alicyclic resins, mixed C5 aliphatic / alicyclic resins, mixed C9 aromatic / alicyclic resins, mixed C5 aliphatic / alicyclic / C9 aromatic resins, aromatically modified alicyclic resins, C9 aromatic resins, and hydrides of the above resins. The notations "C5" and "C9" indicate that the monomers from which these resins are derived are hydrocarbons having 4 to 6 and 8 to 10 carbon atoms, respectively. The term "hydrogenation" includes fully hydrogenated, substantially hydrogenated, and at least partially hydrogenated resins. Partially hydrogenated resins may have, for example, a hydrogenation level of 50%, 70%, or 90%. 【0041】 Suitable hydrocarbon resins include, for example, commercially available products such as: Wingtack® series, Wingtack® Plus, Wingtack® Extra, and Wingtack® STS (all manufactured by Cray Valley); Escorez® 1000 series, Escorez® 2000 series, and Escorez® 5000 series (all manufactured by Exxon Mobil Chemical); Novares® T series, Novares® TT series, Novares® TD series, Novares® TL series, Novares® TN series, Novares® TK series, and Novares® TV series (all manufactured by RUETGERS Novares GmbH); and Kristalex®, Plastolyn®, Piccotex®, Piccolastic®, and Endex® (all manufactured by Eastman Chemicals). 【0042】 Preferably, the tackifying resin TR contains, and more preferably contains, at least one C5 aliphatic hydrocarbon resin having a softening point in the range of preferably 65 to 165°C, more preferably 75 to 135°C, even more preferably 80 to 125°C, and even more preferably 90 to 110°C, as measured by the ring-sphere method in accordance with DIN EN 1238:2011. 【0043】 The heat-expandable composition further contains azodicarbonamide ADCA. The azodicarbonamide preferably has an average particle size of 1 to 30 μm, preferably 4 to 15 μm, and more preferably 8 to 12 μm. Such azodicarbonamide is commercially available, for example, from Dongjin Semichem Co., Ltd. as part of the UNICELL-D series. 【0044】 The heat-expandable composition preferably further comprises at least one accelerator for azodicarbonamide ADCA. Preferred accelerators are urea compounds, more preferably substituted ureas, and more particularly selected from the list of: 3-(3-chloro-4-methylphenyl)-1,1-dimethylurea (chlortolurone), p-chlorophenyl-N,N-dimethylurea (monulone), 3-phenyl-1,1-dimethylurea (phenulone), 3,4-dichlorophenyl-N,N-dimethylurea (diurone), N,N-dimethylurea, N-isobutyl-N',N'-dimethylurea, and 1,1'-(hexane-1,6-diyl)bis(3,3'-dimethylurea). A particularly preferred accelerator is N,N-dimethylurea. 【0045】 It is preferable that the accelerator for azodicarbonamide ADCA accounts for 0.1 to 4% by weight, more preferably 0.25 to 3.5% by weight, and even more preferably 0.5 to 3% by weight, of the total weight of the heat-expandable composition. 【0046】 The heat-expandable composition further contains zinc oxide (ZnO). 【0047】 The heat-expandable composition further comprises a metal salt AMS of a fatty acid containing at least one 16 or 18 carbon atoms, wherein the metal is zinc. 【0048】 Preferably, the metal salt AMS of a fatty acid containing 16 or 18 carbon atoms (where the metal is zinc) is selected from the group consisting of: zinc salts of saturated fatty acids containing 16 carbon atoms, zinc salts of unsaturated fatty acids containing 16 carbon atoms, zinc salts of saturated fatty acids containing 18 carbon atoms, and zinc salts of unsaturated fatty acids containing 18 carbon atoms. 【0049】 It is more preferable that the metal salt AMS of a fatty acid containing at least one 16 or 18 carbon atoms (where the metal is zinc) is selected from the group consisting of: zinc salt of palmitic acid, zinc salt of palmitoleic acid, zinc salt of sapienic acid, zinc salt of stearic acid, zinc salt of oleic acid, zinc salt of elaidic acid, zinc salt of vaccenic acid, zinc salt of linoleic acid, zinc salt of linoleic acid, and zinc salt of alpha-linoleic acid. 【0050】 It is most preferable that the metal salt AMS of a fatty acid containing at least one 16 or 18 carbon atoms (where the metal is zinc) is selected from the group consisting of zinc salts of palmitic acid, zinc salt of stearic acid, zinc salt of oleic acid, and zinc salt of linoleic acid. 【0051】 The most preferred fatty acid metal salt (AMS) is zinc salt of stearic acid (zinc stearate). 【0052】 Surprisingly, it was found that with other metal salts of fatty acids, namely calcium stearate or aluminum stearate, the expansion rate was insufficient, and the odor grade values ​​were higher. This can be seen, for example, by comparing E1 with Ref. 5 and E1 with Ref. 6 in Table 2. 【0053】 The weight ratio of azodicarbonamide ADCA to zinc oxide ZnO (ADCA / ZnO) is 2.0 to 7.5. 【0054】 At ratios less than 2, the expansion rate is insufficient, and the odor grade value becomes high. This can be seen, for example, by comparing E4 and E5, and E1 and E5, in Table 2. At ratios greater than 7.5, the expansion rate is insufficient. This can be seen, for example, by comparing E1 and Ref.1 in Table 2. 【0055】 The weight ratio of azodicarbonamide ADCA to zinc oxide ZnO (ADCA / ZnO) is preferably 2.25 to 6.0, more preferably 2.75 to 5.5, and most preferably 3.0 to 4.5. These preferred ratios are advantageous for increasing the expansion rate and lowering the odor grade value. This can be seen, for example, by comparing E4 and E1, E1 and E5, and E4 and E5 in Table 2. 【0056】 The weight ratio of ADCA / AMS is between 0.75 and 6.5. 【0057】 At ratios below 0.75, the odor class value increases. This can be seen, for example, by comparing E2 and E3 in Table 2. At ratios above 6.5, the odor class value increases. This can be seen, for example, by comparing E1 and Ref.2 in Table 2. 【0058】 The weight ratio of azodicarbonamide ADCA to the fatty acid metal salt AMS (ADCA / AMS) is preferably 1.0 to 6.0, more preferably 1.5 to 5.5, and more preferably 2.5 to 4.5. These preferred ratios are advantageous in increasing the expansion rate and lowering the odor grade value. This can be seen, for example, in the comparison between E1 and Ref. 2, E2, and E3, or between E4 and E6, in Table 2. 【0059】 A weight ratio of azodicarbonamide ADCA to the fatty acid metal salt AMS (ADCA / AMS) of 2.5 to 4.0 is even more preferable. This ratio is advantageous for lowering the odor class value. This can be seen, for example, by comparing E4 and E6 in Table 2. 【0060】 A weight ratio of azodicarbonamide ADCA to the fatty acid metal salt AMS (ADCA / AMS) of 4.0 to 5.5 is even more preferable. This ratio is advantageous in that it provides better adhesion on HDG substrates at a curing temperature of 170°C. This can be seen, for example, by comparing E6 and E4 in Table 2. 【0061】 It is even more advantageous if the weight ratio of azodicarbonamide ADCA to the sum of zinc oxide ZnO and metal salt AMS of at least one fatty acid (ADCA / (ZnO+AMS)) is 0.75 to 6.5, preferably 1.0 to 6.0, more preferably 1.5 to 5.5, and most preferably 2.5 to 4.5. These preferred ratios are beneficial in increasing the expansion rate and lowering the odor grade value. This can be seen, for example, by comparing E4 and E7 in Table 2 with Ref. 4. 【0062】 It is even more preferable if the weight ratio of zinc oxide (ZnO) to the metal salt AMS of at least one fatty acid (ZnO / AMS) is 0.2 to 2.0, preferably 0.3 to 1.75, more preferably 0.5 to 1.5, and most preferably 0.75 to 1.25. These preferred ratios are advantageous in increasing the expansion rate and lowering the odor grade value. This can be seen, for example, in the comparison between E1 and E2 and E3, or between E4 and E6, in Table 2. 【0063】 It is even more advantageous if the weight ratio of at least one type of solid rubber R to azodicarbonamide ADCA is 2.0 to 6.0, preferably 3.0 to 5.0, more preferably 3.5 to 4.5, and most preferably 3.75 to 4.25. 【0064】 Preferably, the heat-expandable composition further contains a vulcanizing VS. 【0065】 Many sulfurization systems based on elemental sulfur, and even more so, sulfurization systems that do not contain elemental sulfur, are preferred. 【0066】 When a sulfurization system based on elemental sulfur is used, it is preferable that the system contains at least one sulfur compound selected from the group consisting of powdered sulfur, more preferably powdered sulfur, precipitated sulfur, highly dispersed sulfur, surface-treated sulfur, and insoluble sulfur. 【0067】 The elemental sulfur-based vulcanization system contains, based on the total weight of the vulcanization system, preferably 1 to 15% by weight, more preferably 5 to 10% by weight, of powdered sulfur, preferably at least one sulfur compound selected from the group consisting of powdered sulfur, precipitated sulfur, highly dispersed sulfur, surface-treated sulfur, and insoluble sulfur. 【0068】 In one or more embodiments, the vulcanization system VS is a vulcanization system that does not contain elemental sulfur. 【0069】 A preferred, elemental sulfur-free vulcanization system includes at least one vulcanizing agent, and optionally at least one organic vulcanization accelerator and / or at least one inorganic vulcanization accelerator. 【0070】 Suitable vulcanizing agents for vulcanizing systems that do not contain elemental sulfur include, for example, organic peroxides, phenolic resins, bisazidoformates, polyfunctional amines, p-quinone dioximes, p-benzoquinone dioximes, p-quinone dioxime dibenzoates, p-nitrosobenzene, dinitrosobenzene, thiuram compounds, bismaleimides, dithiols, and vulcanizing systems crosslinked with (blocked) diisocyanates. 【0071】 Suitable organic vulcanization accelerators for use in vulcanization systems that do not contain elemental sulfur include: thiocarbamates, dithiocarbamates (in the form of their ammonium or metal salts), xanthogenetes, thiuram compounds (monosulfide and disulfide), thiazole compounds, aldehyde-amine accelerators such as hexamethylenetetramine, and guanidine accelerators. 【0072】 Suitable inorganic vulcanization accelerators for use in vulcanization systems that do not contain elemental sulfur include, for example, basic zinc carbonate. 【0073】 In one or more preferred embodiments, the vulcanization system VS is an elemental sulfur-free vulcanization system that comprises at least one vulcanizing agent selected from the group consisting of p-quinone dioxime, p-benzoquinone dioxime, p-quinone dioxime dibenzoate, p-nitrosobenzene, dinitrosobenzene, and thiuram compounds, preferably from the group consisting of p-quinone dioxime, p-benzoquinone dioxime, p-quinone dioxime dibenzoate, tetramethylthiuram disulfide (TMTD), and tetrabenzylthiuram disulfide (TBzTD), preferably from the group consisting of tetramethylthiuram disulfide, and preferably further comprises at least one organic vulcanization accelerator. 【0074】 It is preferable that at least one of the organic vulcanization accelerators is selected from the group consisting of cyclohexylbenzothiazole sulfonamide, mercaptobenzothiazole sulfide (MBTS), diphenylguanidine, and zinc dimethyldithiocarbamate. 【0075】 The elemental sulfur-free vulcanization system VS accounts for preferably 1 to 15% by weight, more preferably 1.5 to 5% by weight, even more preferably 1.5 to 3.5% by weight, and most preferably 1.5 to 3% by weight, of the total weight of the heat-expandable composition. 【0076】 In one or more preferred embodiments, the elemental sulfur-free vulcanization system VS contains 65-95% by weight, preferably 75-90% by weight, of at least one vulcanizing agent selected from the group consisting of p-quinone dioxime, p-benzoquinone dioxime, p-quinone dioxime dibenzoate, tetramethylthiuram disulfide (TMTD), and tetrabenzylthiuram disulfide (TBzTD), and 5-35% by weight, preferably 10-25% by weight, of at least one organic vulcanization accelerator selected from the group consisting of cyclohexylbenzothiazole sulfonamide, mercaptobenzothiazole sulfide (MBTS), diphenylguanidine, and zinc dimethyldithiocarbamate (all percentages are based on the total weight of the vulcanization system VS). 【0077】 In one or more embodiments, the heat-expandable composition further includes at least one plasticizer PL, preferably selected from the group consisting of process oils and liquid polyolefin resins. 【0078】 If at least one plasticizer PL is used, it is preferable that it be present in the heat-expandable composition in an amount of 35% by weight or less, preferably 30% by weight or less, based on the total weight of the heat-expandable composition. 【0079】 In one or more embodiments, at least one plasticizer PL accounts for 10 to 35% by weight, more preferably 15 to 30% by weight, and even more preferably 20 to 30% by weight, of the total weight of the heat-expandable composition. 【0080】 Suitable process oils to be used as at least one plasticizer PL include mineral oils and synthetic oils. In the disclosure of this invention, the term "mineral oil" refers to a liquid hydrocarbon having a lubricating viscosity (i.e., a kinematic viscosity of 1 cSt or more at 100°C) that has been derived from crude oil and subjected to one or more refining and / or hydrotreatment steps, such as fractional distillation, hydrocracking, dewaxing, isomerization, and hydrofinishing, to purify its components and chemically modify it to achieve a set of final performances. Specifically, in the disclosure of this invention, the term "mineral" refers to refined mineral oils that can be defined as Group I to III base oils according to the classification of the American Petroleum Institute (API). 【0081】 Suitable mineral oils for use as at least one type of plasticizer PL include paraffinic, naphthenic, and aromatic mineral oils. Particularly suitable mineral oils include paraffinic and naphthenic oils, which contain relatively low amounts of aromatic components, for example, 25% by weight or less, preferably 15% by weight or less, based on the total weight of the mineral oil. 【0082】 In this disclosure, the term "synthetic oil" refers to a fully synthetic (polyalphaolefin) oil, also known as a Group IV base oil according to the American Petroleum Institute (API) classification. Preferred synthetic oils are produced from liquid polyalphaolefins (PAOs) obtained by polymerizing α-olefins in the presence of a polymerization catalyst, such as a Friedel-Crafts catalyst. Generally, liquid PAOs are high-purity hydrocarbons with paraffinic structures and highly branched side chains. Particularly preferred synthetic oils are those obtained from the so-called "Gas-To-Liquids" process. 【0083】 Preferably, the at least one plasticizer PL contains at least one process oil PL1 selected from the group consisting of naphthenic and paraffinic mineral oils. 【0084】 In the present disclosure, the term "liquid resin" refers to a resin that has fluidity at normal room temperature, a pour point of less than 20°C, and / or a kinematic viscosity of 50,000 cSt or less at 25°C. 【0085】 Examples of liquid polyolefin resins suitable for use as at least one plasticizer PL include liquid polybutene and liquid polyisobutylene (PIB). In the present disclosure, the term "liquid polybutene" refers to a low molecular weight olefin oligomer containing isobutylene and / or 1-butene and / or 2-butene. The ratio of those C4-olefin isomers may vary depending on the manufacturer and grade. When the C4-olefin is solely 1-butene, the substance is called "poly-n-butene" or "PNB". In the present specification, the term "liquid polyisobutylene" refers to a low molecular weight olefin oligomer of isobutylene containing preferably at least 75% by weight, more preferably at least 85% by weight, of repeating units derived from isobutylene. Suitable liquid polybutene and polyisobutylene have an average molecular weight (M n ) of less than 10,000 g / mol, preferably less than 7,500 g / mol, more preferably less than 5,000 g / mol, even more preferably less than 3,500 g / mol, still more preferably less than 2,500 g / mol. 【0086】 Suitable liquid polybutenes and polyisobutylenes are commercially available under the following trade names, for example: Indopol® trade names, e.g., Indopol® H-300 and Indopol® H-1200 (manufactured by Ineos); Glissopal® trade names, e.g., Glissopal® V230, Glissopal® V500, and Glissopal® V700 (manufactured by BASF); Dynapak® trade names, e.g., Dynapak® poly 230 (manufactured by Univar GmbH (Germany)); and Daelim® trade names, e.g., Daelim® PB 950 (manufactured by Daelim Industrial). 【0087】 Preferably, the heat-expandable composition further comprises at least one solid particulate filler F selected from the group consisting of: ground or precipitated calcium carbonate, lime, calcium magnesium carbonate, talcum, gypsum, barite, pyrolysis 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 aluminumoxane, and carbon black. Suitable solid particulate fillers include the fillers listed above, both with and without organic coatings, in commercially available forms. 【0088】 Preferably, at least one solid particulate filler F is present in the heat-expandable composition in the form of fine particulate matter. The term "fine particulate matter" refers to its median particle size d 50 However, it refers to particulate matter not exceeding 500 μm, preferably 350 μm, and more preferably 150 μm. "Median particle size" 50 In this disclosure, the term "50% of the total volume of particles is d 50This refers to particle size that is smaller than the specified value. 【0089】 In one or more embodiments, at least one of the solid particulate fillers F has a median particle size d in the range of 0.5 to 150 μm, preferably 1 to 100 μm, more preferably 1 to 50 μm, even more preferably 1 to 25 μm, and even more preferably 1 to 10 μm. 50 It has. 【0090】 In one or more embodiments, the at least one solid particulate filler F comprises at least one mineral filler selected from the following list: ground or precipitated calcium carbonate, lime, calcium magnesium carbonate, talcum, gypsum, graphite, barite, silica, silicate, mica, wollastonite, and carbon black. 【0091】 In one or more embodiments, at least one type of solid particulate filler F accounts for 5 to 50% by weight, preferably 10 to 45% by weight, more preferably 12.5 to 40% by weight, and even more preferably 15 to 35% by weight, of the total weight of the heat-expandable composition. 【0092】 Preferably, the heat-expandable composition further contains at least one styrene block copolymer SC. 【0093】 Suitable block copolymers SC include, in particular, block copolymers containing polystyrene blocks and polybutadiene blocks and / or polyisoprene blocks. These materials are generally available as pure triblock copolymers (also known as SIS and SBS block copolymers) and diblock copolymers (SI and SB block copolymers). Furthermore, styrene block copolymers are also commercially available as mixtures of diblock copolymers and triblock copolymers. Suitable styrene block copolymers may have a linear, radial, or star-shaped structure, but a linear structure is particularly preferred. 【0094】 In one or more embodiments, the at least one styrene block copolymer SC comprises at least one styrene isoprene block (SI) and / or triblock (SIS) copolymer, and / or at least one styrene-butadiene diblock (SB) and / or triblock (SBS) copolymer. 【0095】 Suitable SI, SIS, SB, and SBS block copolymers are commercially available under trade names such as: Vector® from TSRC / Dexco, e.g., Vector® 4000-series; and Kraton Polymers, Kraton® D-series. 【0096】 In one or more embodiments, at least one styrene block copolymer SC accounts for 4 to 20% by weight, preferably 5 to 15% by weight, and more preferably 6 to 10% by weight, of the total weight of the heat-expandable composition. 【0097】 It is even more preferable that the heat-expandable composition contains less than 5% by weight, preferably less than 2.5% by weight, and more preferably less than 1% by weight of at least one epoxy resin, preferably at least one liquid epoxy resin, based on the total weight of the heat-expandable composition. 【0098】 The liquid epoxy resin typically includes a liquid resin of formula (I). [ka] (In the formula, R' and R'' are independently a hydrogen atom or a methyl group, and s has an average value between 0 and 1). A liquid resin of formula (I) having an average value of exponent s less than 0.2 is preferred. 【0099】 The liquid epoxy resins of formula (I) are diglycidyl ethers of bisphenol A, bisphenol F, and bisphenol A / F, where A represents acetone and F represents formaldehyde, which function as reactants for preparing these bisphenols. Thus, as R' and R'' in formula (I), the bisphenol A liquid resin has a methyl group, the bisphenol F liquid resin has a hydrogen atom, and the bisphenol A / F liquid resin has both a methyl group and a hydrogen atom. In the case of bisphenol F, it can exist as positional isomers derived particularly from 2,4'- and 2,2'-hydroxyphenylmethane. 【0100】 It is even more preferable that the heat-expandable composition contains less than 1% by weight, preferably less than 0.5% by weight, and more preferably less than 0.1% by weight, of at least one polyvinyl chloride (PVC) resin and / or acrylic resin, based on the total weight of the heat-expandable composition. The polyvinyl chloride (PVC) resin may be a homopolymer or copolymer of polyvinyl chloride, preferably a copolymer of polyvinyl chloride. The acrylic resin in the acrylic resin powder may be a homopolymer or a copolymer. 【0101】 It is advantageous if the heat-expandable composition is substantially free of physical and chemical blowing agents other than azodicarbonamide ADCA, preferably substantially free of chemical blowing agents. The expression "essentially free of" should be understood to mean that the heat-expandable composition contains only trace amounts of the aforementioned physical and chemical blowing agents other than azodicarbonamide ADCA, for example, less than 0.25% by weight, preferably less than 0.15% by weight, more preferably less than 0.05% by weight, and even more preferably less than 0.01% by weight, based on the total weight of the heat-expandable composition. 【0102】 The heat-expandable composition is preferably substantially free of, or preferably completely free of, the following exothermic chemical blowing agents selected from the group consisting of: OBSH, DNPT (dinitrosopentamethylenetetraamine), PTSS (p-toluenesulfonyl semicarbazide), BSH (benzene-4-sulfonyl hydrazide), TSH (4-toluenesulfonyl hydrazide), and 5-PT (5-phenyltetrazole). The term "free of" should be understood to mean that the amount of the compounds listed above is 0% by weight based on the total weight of the heat-expandable composition. 【0103】 It is even more preferable if the heat-expandable composition has a viscosity higher than 1000 Pa·s, preferably higher than 2000 Pa·s, as measured by a rheometer equipped with a heating plate (MCR 301, AntonPaar) (gap 1000 μm, measuring plate diameter: 25 mm (plate / plate), deformation 0.01~10% (5 Hz), temperature: 20°C). 【0104】 If the heat-expandable composition is tacky at 23°C, the more preferable term "tacky" refers, as used herein, to sufficient surface tack at 23°C, preferably in terms of instantaneous adhesion or tackiness, such that when a thumb is pressed against the surface of the heat-expandable composition and a pressure of 5 kg is applied for 1 second, the thumb remains adhered to the surface of the heat-expandable composition. Preferably, in this manner, after pressing the surface of the heat-expandable composition with a thumb at 23°C and applying a pressure of 5 kg for 1 second, a heat-expandable composition having an inherent weight of 50 g can be lifted for at least 5 seconds. 【0105】 In one or more embodiments, the heat-expandable composition after curing has a volume increase of 1500% or less, preferably 1000% or less, and more preferably 750% or less, compared to the uncured composition, where this volume increase is measured in relation to the mass of the sample measured with a precision balance in deionized water using the density measurement method (Archimedes' principle) of DIN EN ISO 1183. 【0106】 In one or more embodiments, the heat-expandable composition after curing has a volume increase of 25 to 1000%, preferably 50 to 750%, more preferably 75 to 500%, and even more preferably 100 to 500%, compared to the uncured composition. 【0107】 The heat-expandable compositions according to the present invention can be manufactured by mixing their components in various suitable mixing devices, such as: a dispersion mixer, a planetary mixer, a twin-screw mixer, a continuous mixer, an extruder, or a twin-screw extruder. 【0108】 Preferably, at least one solid rubber R and (if used) at least one plasticizer PL are mixed in a separate step using a kneader, preferably a sigma blade kneader, to obtain a homogeneous mixture. This homogeneous mixture is then preferably mixed with the remaining components of the heat-expandable composition in the preferred mixing apparatus described above. 【0109】 To facilitate the processing of the components into a homogeneous mixture by reducing viscosity and / or melting individual components, it would be advantageous to heat the components before or during mixing, either by applying an external heat source or by frictional heat generated by the mixing process itself. However, care must be taken to ensure that the activation temperature of the azodicarbonamide and, if applicable, the vulcanizing system VS is not exceeded during the mixing process, for example, by monitoring the temperature and, if appropriate, by using a cooling device. 【0110】 The heat-expandable compositions according to the present invention obtained using the process described above are storage stable under normal storage conditions. The term "storage stable" in this disclosure means a substance that can be stored for a long period, for example, at least one month, and particularly at least three months, under specific storage conditions without any significant change in its usability. The term "typical storage conditions" in this context means a temperature of 60°C or less, and particularly 50°C or less. 【0111】 Another subject of the present invention is a shielding component for an open or hollow structure, wherein the component includes a heat-expandable composition according to the present invention. 【0112】 In one or more embodiments, the heat-expandable composition of the shielding component preferably has a sheet-like structure having the following dimensions: - A thickness in the range of 0.5 to 10 mm, preferably 1 to 7.5 mm, more preferably 1 to 6 mm, and / or - A width in the range of 1 to 30 cm, preferably 2 to 20 cm, more preferably 2 to 15 cm, and / or - A length in the range of 5 to 30 cm, preferably 10 to 30 cm, and more preferably 10 to 25 cm. 【0113】 In one or more further embodiments, the shielding component further includes a support on which the heat-expandable composition is deposited or attached. Such a design is more economical and allows for easy attachment of the shielding component to the wall surface of the structure to be shielded, for example, by incorporating pins, bolts, or hooks onto the support component. Furthermore, the mechanical performance and stability of the shielding component can be improved by appropriately designing the support component. 【0114】 If a support is used for the shielding component, it may be made of any material that can be processed and molded. Suitable materials for the support include polymer materials such as plastics, elastomers, thermoplastics, and blends thereof. Preferred thermoplastic materials include, but are not limited to, polymers such as polyurethane, polyamide, polyester, polyolefin, polysulfone, polyethylene terephthalate (PET), polyvinyl chloride (PVC), and chlorinated polyolefin. Particularly preferred are high-temperature stable polymers 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 metals, especially aluminum or steel, or naturally occurring organic materials such as wood or other (pressure-processed) fibrous materials. Furthermore, glassy or ceramic materials can also be used. It is also possible to use combinations of such materials. Such materials could be used, for example, as fillings or molds, using fibers, minerals, clay, silicates, carbonates, or combinations thereof. 【0115】 The support can further take any shape or dimensions. It may also consist of several unconnected components. For example, it may be solid, hollow, or foamed, or it may exhibit a grid-like structure. The surfaces of the components of the support may typically be smooth, rough, or structured, depending on the intended use of the shielding components. 【0116】 The shielding components according to the present invention can be manufactured, for example, by injection molding, punching or stamping, extrusion, calendering, or hot pressing of a heat-expandable composition. 【0117】 If the shielding component includes a support, it can be manufactured, for example, by injection molding a heat-expandable composition onto the support or by co-extrusion with the support. The details of the manufacturing process for a shielding component including a support depend largely on the material of the support. If the material of the support can be (injection) molded or extruded, the shielding component can be manufactured by a two-step injection molding process or by co-extrusion molding of the support and the heat-expandable composition. 【0118】 Preferably, the shielding component does not include a support and is adhesive at 23°C. Therefore, such a shielding component does not require a support and / or fasteners, and due to its adhesiveness, it can be attached to a substrate, preferably a cavity or part of a hollow structure, simply by being adhered to the substrate. 【0119】 Another subject of the present invention is a method for sealing and / or shielding a cavity or hollow structure, wherein a shielding component according to the present invention is introduced into the cavity or hollow structure, and then heated and expanded so that the cavity or hollow structure is at least partially filled with the expanded composition. 【0120】 The temperature of the thermal expansion step is preferably 100 to 250°C, more preferably 100 to 200°C, even more preferably 110 to 200°C, and even more preferably 110 to 185°C. The preferred time for the thermal expansion step, i.e., the preferred baking time for the heat-expandable composition, is 5 to 90 minutes, more preferably 10 to 60 minutes, and even more preferably 10 to 30 minutes. 【0121】 In one or more embodiments, the heat-expandable composition of the shielding component, upon activation, gives a volume increase of 25 to 2000%, preferably 50 to 1500%, more preferably 75 to 1000%, and even more preferably 100 to 750%, compared to the original volume before expansion, where the volume increase is measured in relation to the mass of the sample measured by a precision balance in deionized water using the density measurement method (Archimedes' principle) of DIN EN ISO 1183. 【0122】 A further subject of the present invention is the use of azodicarbonamide ADCA, zinc oxide ZnO, and at least one metal salt AMS of a fatty acid containing 16 or 18 carbon atoms (wherein the metal is zinc, preferably the metal salt AMS of the fatty acid is zinc stearate) in a heat-expandable composition comprising at least one solid rubber R and at least one tackifying resin TR, the object of which is the reduction of odor formed after heating the heat-expandable composition at a temperature of 180°C for 30 minutes. 【0123】 Preferably, the odor test is carried out according to Method C3 of VDA 270, more preferably as described in the Experimental section. 【0124】 The weight ratio of azodicarbonamide ADCA to zinc oxide ZnO (ADCA / ZnO) is 2.0 to 7.5, and the weight ratio of azodicarbonamide ADCA to the metal salt AMS of fatty acids (ADCA / AMS) is 0.75 to 6.5. 【0125】 The preferred heat-expandable composition, and its preferred components ADCA, ZnO, AMS, R, and TR, are the same as those previously specified as preferred. 【0126】 The reduction in odor generation is compared to the previously mentioned heat-expandable composition in which the weight ratio of azodicarbonamide ADCA to zinc oxide ZnO (ADCA / ZnO) and / or the weight ratio of azodicarbonamide ADCA to the fatty acid metal salt AMS (ADCA / AMS) falls outside the above range. [Examples] 【0127】 The following chemical substances, listed in Table 1, were used in the formulation of the heat-expandable composition. 【0128】 [Table 1] 【0129】 Preparation of heat-expandable compositions All of the formulations of the present invention (E1-E7) and non-inventive formulations (Ref.1-Ref.9) having the compositions shown in Table 2 were prepared according to the following procedure. 【0130】 In the first step, solid rubber SBR was mixed in a Sigma blade mixer for 15 minutes. Then, fillers, tackifiers, and plasticizers were added over a period of 45-60 minutes. After cooling, the remaining reactive components were added (total weight of the final composition, approximately 300g) and mixed for 30 minutes. The mixed composition was then pressed to a thickness of 2mm for use (a 2mm thick sample for testing physical properties). 【0131】 Volume expansion First, the test material was molded into strips with dimensions of 25 × 25 × 2 mm (length × width × thickness), and then baked at 160°C, 180°C, 200°C, and 220°C for 20 or 25 minutes. Next, the volume expansion (in units, percentage) was calculated using the following formula: (V after -V before ) / V beforeThe volume of the strips before and after baking was determined based on density measurements. The density of the strips was determined according to the DIN EN ISO 1183 standard, using the water immersion method in deionized water (Archimedes' principle), and the mass was determined using a precision balance. 【0132】 Odor Odor testing was conducted according to VW specification PV3900, which corresponds to VDA270 method C3. Free-foaming samples were placed in a 100 cm³ container. 3 The samples were prepared to the size required to achieve the foam volume. The sample dimensions (cm) for a 2L jar / 100ccm were 5.5 × 9.9. A bake cycle of 30 minutes at 180°C was used, followed by conditioning of the samples at 80°C for 2 hours, then cooling to 60°C for 5 minutes, and their odor was evaluated using the following odor classification. 1: Imperceptible 2: It is perceived, but not to the point of being bothersome. 3: More strongly perceived, but not bothersome. 4: I'm curious 5: More of a concern 6: Unbearable 【0133】 Adhesiveness The material (approximately 25 x 100 x 2 mm thick) was applied to a 4 x 6-inch panel. The substrates evaluated were HDG treated with CRS and Quaker 61 AUS oil. The material was placed on the panel and baked at 170°C for 30 minutes ("170°C adhesion") and 190°C for 30 minutes ("190°C adhesion"), then cooled to room temperature over 4 hours before being tested for cohesive failure. Adhesion was tested by inserting the tip of a pointed spatula under the end of a strip of the material, grasping the sealer tab, and performing a 180-degree peel. For these panels, the failure mode was checked as either cohesive failure ("cf") or adhesive failure ("af"). 【0134】 The results of these experiments are shown in Table 3. The weight ratio of zinc oxide to zinc stearate is expressed as "ZnO / AMS", the weight ratio of azodicarbonamide to zinc oxide is expressed as "ADCA / ZnO", the weight ratio of azodicarbonamide to zinc stearate is expressed as "ADCA / AMS", and the weight ratio of azodicarbonamide to the sum of zinc oxide and zinc stearate is expressed as "ADCA / (ZnO+AMS)". 【0135】 [Table 2] 【0136】 [Table 3]

Claims

[Claim 1] A heat-expandable composition, a) At least one type of solid rubber R, b) At least one type of tackifying resin TR, c) Azodicarbonamide ADCA, d) Zinc oxide (ZnO), e) A metal salt AMS of at least one fatty acid containing 16 or 18 carbon atoms, wherein the metal is zinc, and preferably the metal salt AMS of the fatty acid is zinc stearate. Includes, The weight ratio of the azodicarbonamide ADCA to the zinc oxide ZnO (ADCA / ZnO) is 2.0 to 7.

5. The weight ratio of the azodicarbonamide ADCA to the metal salt AMS of the fatty acid (ADCA / AMS) is 0.75 to 6.

5. A heat-expandable composition. [Claim 2] The heat-expandable composition according to claim 1, wherein the weight ratio of azodicarbonamide ADCA to zinc oxide ZnO (ADCA / ZnO) is 2.25 to 6.0, preferably 2.75 to 5.5, and more preferably 3.0 to 4.

5. [Claim 3] The heat-expandable composition according to claim 1 or 2, wherein the weight ratio of the azodicarbonamide ADCA to the metal salt AMS of the fatty acid (ADCA / AMS) is 1.0 to 6.0, preferably 1.5 to 5.5, and more preferably 2.5 to 4.

5. [Claim 4] The heat-expandable composition according to any one of claims 1 to 3, wherein the weight ratio of the azodicarbonamide ADCA to the sum of the zinc oxide ZnO and the metal salt AMS of at least one fatty acid (ADCA / (ZnO + AMS)) is 0.75 to 6.5, preferably 1.0 to 6.0, more preferably 1.5 to 5.5, and most preferably 2.5 to 4.

5. [Claim 5] The heat-expandable composition according to any one of claims 1 to 4, wherein the weight ratio of zinc oxide ZnO to the metal salt AMS of the at least one fatty acid (ZnO / AMS) is 0.2 to 2.0, preferably 0.3 to 1.75, more preferably 0.5 to 1.5, and most preferably 0.75 to 1.

25. [Claim 6] The heat-expandable composition according to any one of claims 1 to 5, wherein the weight ratio of at least one solid rubber R to the azodicarbonamide ADCA is 2.0 to 6.0, preferably 3.0 to 5.0, more preferably 3.5 to 4.5, and most preferably 3.75 to 4.

25. [Claim 7] The heat-expandable composition according to any one of claims 1 to 6, wherein the heat-expandable composition comprises less than 5% by weight, preferably less than 2.5% by weight, and more preferably less than 1% by weight of at least one epoxy resin, preferably at least one liquid epoxy resin, based on the total weight of the heat-expandable composition. [Claim 8] The heat-expandable composition according to any one of claims 1 to 7, wherein the at least one solid rubber R is selected from the group consisting of butyl rubber, halogenated butyl rubber, styrene-butadiene rubber (SBR), ethylene-propylene rubber (EPR), ethylene-propylene diene monomer rubber (EPDM), natural rubber, cis-1,4-polyisoprene, and polybutadiene rubber, preferably styrene-butadiene rubber (SBR). [Claim 9] The heat-expandable composition according to any one of claims 1 to 8, wherein the at least one type of solid rubber R accounts for 5 to 40% by weight, preferably 7.5 to 35% by weight, and more preferably 15 to 25% by weight of the total weight of the heat-expandable composition. [Claim 10] The heat-expandable composition according to any one of claims 1 to 9, wherein the at least one tackifying resin TR accounts for 2 to 20% by weight, preferably 4 to 12% by weight, and more preferably 6 to 10% by weight of the total weight of the heat-expandable composition. [Claim 11] The heat-expandable composition according to any one of claims 1 to 10, further comprising a vulcanizing system VS, wherein the vulcanizing system VS is a vulcanizing system that does not contain elemental sulfur, preferably comprising at least one vulcanizing agent selected from the group consisting of p-quinone dioxime, p-benzoquinone dioxime, p-quinone dioxime dibenzoate, tetramethylthiuram disulfide (TMTD), and tetrabenzylthiuram disulfide (TBzTD), preferably tetramethylthiuram disulfide, and preferably further comprising at least one organic vulcanization accelerator and / or at least one inorganic vulcanization accelerator, more preferably at least one organic vulcanization accelerator. [Claim 12] The heat-expandable composition according to any one of claims 1 to 11, wherein the heat-expandable composition substantially does not contain any physical blowing agent or chemical blowing agent other than c) azodicarbonamide ADCA, preferably substantially does not contain any chemical blowing agent. [Claim 13] A shielding component for an open structure or a hollow structure, wherein the component comprises a heat-expandable composition according to any one of claims 1 to 12. [Claim 14] The shielding component according to claim 13, wherein the heat-expandable composition has a sheet-like structure, preferably having a thickness in the range of 0.5 to 10 mm, preferably 1 to 7.5 mm, and / or a length in the range of 5 to 30 cm, preferably 10 to 25 cm, and / or a width in the range of 1 to 30 cm, preferably 2 to 20 cm. [Claim 15] A method for sealing and / or shielding a cavity or hollow structure, comprising introducing a shielding component according to claim 13 or 14 into the cavity or hollow structure, and then heating and expanding it so that the cavity or hollow structure is at least partially filled with the expanded composition. [Claim 16] In a heat-expandable composition comprising at least one solid rubber R and at least one tackifying resin TR, the use of azodicarbonamide ADCA, zinc oxide ZnO, and a metal salt AMS of at least one fatty acid containing 16 or 18 carbon atoms is used to suppress the generation of odor after heating the heat-expandable composition at a temperature of 180°C for 30 minutes, wherein the odor test is carried out according to VDA 270 method C3, more preferably as described in the Examples section, the metal is zinc, preferably the metal salt AMS of the fatty acid is zinc stearate, the weight ratio of azodicarbonamide ADCA to zinc oxide ZnO (ADCA / ZnO) is 2.0 to 7.5, and the weight ratio of azodicarbonamide ADCA to the metal salt AMS of the fatty acid (ADCA / AMS) is 0.75 to 6.5.

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