Thermally expandable composition comprising a polymeric foaming agent

Abstract

The invention relates to a thermally expandable composition comprising: a) At least one thermoplastic polymer TP and / or at least one solid rubber R and b) At least one polymeric blowing agent BA selected from the group consisting of sulfonyl hydrazide-functionalized polymers, sulfonyl semicarbazide-functionalized polymers, carbamate-functionalized polymers, and ureido carbamate-functionalized polymers, wherein the polymeric blowing agent BA has a number average molecular weight (Mn) determined by gel permeation-chromatography (GPC) using polystyrene 0 as standard of at least 500 g / mol, preferably at least 750 g / mol.

Description

[0001] THERMALLY EXPANDABLE COMPOSITION COMPRISING A POLYMERIC FOAMING AGENT

[0002] Technical field

[0003] The present invention relates to thermally expandable compositions and use thereof for providing baffle and / or reinforcement elements. Such elements are particularly suitable for use in sealing, baffling, and / or reinforcing of hollow structures, for example cavities in a hollow structural part of an automotive vehicle.

[0004] Background of the invention

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

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

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

[0008] Currently employed thermally expandable compositions often consist of cross-linkable polymer network comprising thermoplastic polymers, for example, polyolefins or ethylene-vinyl acetate polymers. In order to obtain foams, these compositions furthermore contain blowing agents. Under activation conditions, such as elevated temperature, curing of the cross-linkable network takes place, while simultaneously the blowing agent decomposes and releases gases. This leads to a volume expansion and the formation of a stable foam, which in ideal cases fills the cavity as intended and adheres to its walls.

[0009] For thermally expandable thermoplastic compositions used in automotive manufacturing, i.e. for baffle and reinforcement elements in hollow car body structures, the nowadays most important chemical blowing agent is azodicarbonamide (ADCA), also called azo(bis)formamide. It has a broad decomposition temperature range adjustable between about 140 °C and 200 °C and exhibits a high decomposition gas volume of approximately 200 mL / g. Furthermore, it has a very attractive price / performance ratio.

[0010] However, recently raised concerns by European legislators regarding potentially adverse health effects for this class of compounds may lead to restrictions or even a ban of their use in expandable thermoplastic compositions, which increases demand for viable alternatives. Some alternative chemical blowing agents are already available, such as sodium bicarbonate, oxybis(benzenesulfonyl hydrazide) (OBSH), toluenesulfonyl hydrazide (TSH), p-toluenesulfonyl semicarbazide (TSSC), 5-phenyl tetrazole (5-PT), or N-N’- dinitrosopentamethylene tetramine (DNPT). These compounds however are only useful in limited applications, as they either suffer from poor decomposition gas volume, release toxic, reactive gases such as formaldehyde, or require activation temperatures difficult to meet for baffle or reinforcement elements in automotive manufacturing.

[0011] Endothermic chemical blowing agents have the advantage that they are not hazardous or explosive, and that fewer volatile organic compounds (VOCs) are created during their decomposition. The decomposition products are essentially carbon dioxide and water. However, some of the commonly used endothermic blowing agents, such as hydrogen carbonate (bicarbonate), and carbonate salts have the general disadvantage of being hydrophilic. Consequently, these types of blowing agents tend to increase the water absorption if they are not completely reacted during the expansion / curing step and thus remain in the produced foam. Increased water absorption is especially undesirable in automotive sector, wherein the foamed compositions are used to achieve improved corrosion resistance and long-term durability. Additionally, conventional blowing agents often exhibit uncontrolled VOC release that continues overtime after expansion, which can lead to ongoing emissions and potential environmental concerns. Different blowing agents are known from US3709844A or KR20140064226A.

[0012] Therefore, there is still an unmet demand for an alternative chemical blowing agent which is commercially viable and shows at least comparable performance as ADCA regarding gas volume and decomposition temperature range and which can be easily incorporated in thermally expandable thermoplastic and elastomeric compositions without increasing the water absorption of such compositions that are useful, for example, for baffle or reinforcement elements in automotive manufacturing or building insulation.

[0013] Summary of the invention The object of the present invention is to provide a storage-stable thermally expandable composition that is able to expand uniformly and to cure to form a stable foam structure over a wide range of temperatures without the use of commonly used exothermic blowing agents, particularly ADCA or OBSH. The produced foam should exhibit decreased water uptake and good adhesion to metallic, even oily, surfaces and other substrates commonly used in manufactured articles, particularly automotive vehicles.

[0014] Surprisingly, it was discovered that the object can be achieved with the features described herein.

[0015] Specifically, according to embodiments of the invention, a thermally expandable composition is proposed, the composition comprising: a) At least one curable polymer P and b) At least one polymeric blowing agent BA selected from the group consisting of sulfonyl hydrazide-functionalized polymers, sulfonyl semicarbazide-functionalized polymers, carbamate-functionalized polymers, and ureido carbamate-functionalized polymers, wherein the blowing agent BA has a number average molecular weight (Mn) determined by gel permeation-chromatography (GPC) using polystyrene as standard of at least 500 g / mol, preferably at least 750 g / mol.

[0016] As it turned out, the polymeric blowing agent exhibits a comparable performance compared to the commonly used exothermic blowing agents, including ADCA and OBSH. Furthermore, thermally expandable compositions comprising the polymeric blowing agent were found to have decreased water absorption compared to similar compositions comprising endothermic blowing agents, particularly hydrogen carbonate.

[0017] Additional aspects of the present invention are defined in further independent claims. Particularly preferred embodiments are outlined throughout the description and the dependent claims. Detailed description of the invention

[0018] The subject of the present invention is a thermally expandable composition comprising: a) At least one curable polymer P and b) At least one polymeric blowing agent BA selected from the group consisting of sulfonyl hydrazide-functionalized polymers, sulfonyl semicarbazide-functionalized polymers, carbamate-functionalized polymers, and ureido carbamate-functionalized polymers, wherein the blowing agent BA has a number average molecular weight (Mn) determined by gel permeation-chromatography (GPC) using polystyrene as standard of at least 500 g / mol, preferably at least 750 g / mol.

[0019] Substance names beginning with "poly" designate substances which formally contain, per molecule, two or more of the functional groups occurring in their names. For instance, a polyol refers to a compound having at least two hydroxyl groups. A polyether refers to a compound having at least two ether groups.

[0020] The term “polymer” refers to a collective of chemically uniform macromolecules produced by a polyreaction (polymerization, polyaddition, polycondensation) where the macromolecules differ with respect to their degree of polymerization, molecular weight and chain length. The term also comprises derivatives of said collective of macromolecules resulting from polyreactions, that is, compounds which are obtained by reactions such as, for example, additions or substitutions, of functional groups in predetermined macromolecules and which may be chemically uniform or chemically non-uniform. The term “molecular weight” refers to the molar mass (g / mol) of a molecule or a part of a molecule, also referred to as “moiety”. The term “average molecular weight” refers to number average molecular weight (Mn) of an oligomeric or polymeric mixture of molecules or moieties. The molecular weight may be determined by conventional methods, preferably by gel permeation-chromatography (GPC) using polystyrene as standard, styrene-divinylbenzene gel with porosity of 100 Angstrom, 1000 Angstrom and 10000 Angstrom as the column and depending on the molecule, tetrahydrofurane as a solvent, at 35 °C, or 1 ,2,4-trichlorobenzene as a solvent, at 160 °C.

[0021] The term “melting temperature” refers to a temperature at which a material undergoes transition from the solid to the liquid state. The melting temperature (Tm) is preferably determined by differential scanning calorimetry (DSC) according to ISO 11357-3 standard using a heating rate of 2 °C / min. The measurements can be performed with a Mettler Toledo DSC 3+ device and the Tm values can be determined from the measured DSC-curve with the help of the DSC-software. In case the measured DSC- curve shows several peak temperatures, the first peak temperature coming from the lower temperature side in the thermogram is taken as the melting temperature (Tm).

[0022] In embodiments, the polymeric blowing agents of the present invention enable a controlled VOC generation characteristics, with substantially all VOC release occurring during the expansion process and / or no significant VOC release after expansion. Thermogravimetric analysis data showing that the polymeric blowing agent releases its mass, for example approximately 40% of its mass, at the characteristic decomposition temperature and then remains stable, unlike conventional blowing agents that exhibit continuous VOC release over extended temperature ranges.

[0023] The “amount or content of at least one component X” in a composition, for example “the amount of the at least one thermoplastic polymer TP” refers to the sum of the individual amounts of all thermoplastic polymers TP contained in the composition. For example, in case the at least one thermoplastic polymer TP comprises 20 wt.-% of the total weight of the composition, the sum of the amounts of all thermoplastic polymers TP contained in the composition equals 20 wt.-%.

[0024] The thermally expandable composition of the present invention comprises at least one polymeric blowing agent BA selected from the group consisting of sulfonyl hydrazide- functionalized polymers, sulfonyl semicarbazide-functionalized polymers, carbamate- functionalized polymers, and ureido carbamate-functionalized polymers. These polymeric blowing agents can exhibit controlled volatile organic compound (VOC) generation with substantially all VOC release occurring during expansion and / or no significant VOC release after expansion, providing environmental and safety advantages over conventional blowing agents.

[0025] In embodiments, the polymer of the polymeric blowing agent BA is selected from polystyrene, styrene block copolymer, poly(meth)acrylate, polyurethane, and polysiloxane, preferably from polystyrene, styrene block copolymer, polymethylmethacrylate (PM MA), polyurethane, and polysiloxane.

[0026] Suitable styrene block copolymers include, particularly, the ones of type S-X-S, S-X- P, or M-X-S, wherein the S designates a styrene block, M a methacrylate block, P a propylene block, and X an elastic a-olefin block, especially selected from the group consisting of butylene, ethylene / butylene, ethylene / propylene, ethylene-(ethylene- propylene), isoprene, and isoprene / butadiene. Suitable styrene block copolymers can have a linear, radial, or star structure, wherein the linear structure may be preferred.

[0027] In this document, the term “polyurethane polymer” refers to polymers prepared by the so called diisocyanate polyaddition process. These also include those polymers which are virtually or entirely free from urethane groups. Examples of polyurethane polymers are polyether-polyurethanes, polyester-polyurethanes, polyether-polyureas, polyureas, polyester-polyureas, polyisocyanurates and polycarbodiimides.

[0028] Furthermore, the term “polysiloxane” designates polymers composed of repeating units of RR'SiO, where R and R’ are identical or different hydrocarbon groups. Functionalized polysiloxanes having some of the R and / or R' groups been replaced by or substituted with substituent groups are also considered “polysiloxanes” according to definition of the present disclosure.

[0029] In exemplary embodiments, the sulfonyl hydrazide-functionalized polymer is a compound of formula (I) wherein Ri is a polymeric backbone, h has a value of 0 or 1 , i has a value of 3 or more, and wherein R2 represents a moiety of formula (II)

[0030] Particularly, the polymeric backbone R1 may be a styrene block copolymer or a poly(meth)acrylate, such as polymethylmethacrylate (PMMA).

[0031] In exemplary embodiments, the sulfonyl hydrazide-functionalized polymer is selected from:

[0032] wherein j is 1 or 2, k is 1 or 2, n is 0, 1 , or 2, m is 1 or 2, and o is 2 or more.

[0033] In further exemplary embodiments, the sulfonyl semicarbazide-functionalized polymer is a compound of formula (III) or a compound of formula (IV) wherein R3 is a polymeric backbone,

[0034] R4 is a hydrogen atom, a linear or branched alkyl group, a cycloaliphatic group or an aryl or an alkyl aryl group, and p has a value of 1 , 2, or 3. Particularly, the polymeric backbone R3 may be a polysiloxane or a polyurethane.

[0035] In further exemplary embodiments, the carbamate-functionalized polymer is a compound of formula (V) or a compound of formula (VI) wherein Rs is a polymeric backbone,

[0036] Re is a linear or branched C2 to C4 alkyl group,

[0037] R7 is a hydrogen atom, a substituted dicarbamate or a tertiary carbamate,

[0038] Rs is a tertiary alkyl group, particularly a tertiary butyl group, and q is 1 , 2, 3, or 4.

[0039] Especially, the polymeric backbone Rs may be a polysiloxane or a polyurethane.

[0040] In further exemplary embodiments, the ureido carbamate-functionalized polymer is a compound of formula (VII) wherein Re is a linear or branched C2 to C4 alkyl group,

[0041] R9 is a polymeric backbone,

[0042] R10 is a linear or branched alkyl group, a cycloaliphatic group or an aryl or an alkyl aryl group,

[0043] R11 is a hydrogen atom, a substituted dicarbamate or tertiary carbamate,

[0044] R12 is a tertiary alkyl group, particularly a tertiary butyl group, and t is 1 , 2, or 3.

[0045] Especially, the polymeric backbone R9 may be a polysiloxane or a polyurethane.

[0046] The at least one polymeric blowing agent BA may have a maximum decomposition peak temperature measured by Differential Scanning Calorimetry (DSC) in the range of 135 - 250 °C, such as 145 - 225 °C, particularly 155 - 200 °C, especially 165 - 200 °C. Furthermore, the maximum decomposition peak measured by DSC may be determined by a DSC822e differential scanning calorimeter from Mettler-Toledo by keeping the sample for 2 min at 25 °C, then heating the sample from 25°C to 280 °C at a rate of 5°C / min, then keeping the sample for 2 min at 280 °C and finally cooling the sample from 280 °C to 25 °C at a rate of 10°C / min.

[0047] The controlled VOC generation characteristics of the polymeric blowing agents may be demonstrated by thermogravimetric analysis, which shows that substantially all volatile organic compounds are released during the initial decomposition phase corresponding to the expansion process, with minimal additional VOC release at higher temperatures. In exemplary embodiments, the thermally expandable composition comprises 0.5 - 35 wt.-%, preferably 1 .5 - 30 wt.-%, more preferably 5 - 25 wt.-%, even more preferably 7.5 - 25 wt.-% of the polymeric blowing agent BA.

[0048] The thermally expandable composition contains, in addition to the polymeric blowing agent BA, a curable polymer P (also called curable polymer component P).

[0049] Particularly, the curable polymer P may be composed of one or more different types of curable polymers, all of which are different from the at least one polymeric blowing agent BA.

[0050] The term “curable polymer” refers in the present disclosure to polymeric compounds, which may be cured via curing reactions comprising forming of bonds resulting, for example, in chain extension and / or crosslinking of polymer chains.

[0051] Curing of curable polymer(s) may proceed based on different types of curing reactions, which may also take place simultaneously, such as a free radical reaction, a sulfur vulcanization reaction, a polycondensation reaction, a polyaddition reaction, or based one any other curing mechanism that is suitable for curing of the curable polymer(s).

[0052] In embodiments, the curable polymer P comprises at least one curable polymer is selected from thermoplastic polymers, solid rubbers, epoxy-functional polymers, and acid anhydride-functional polymers.

[0053] In embodiments, the thermally expandable composition comprises at least 5 wt.-%, particularly at least 15 wt.-%, especially at least 25 wt.-% of the curable polymer P.

[0054] In further embodiments, the thermally expandable composition comprises at least 35 wt.-%, particularly at least 50 wt.-%, especially at least 65 wt.-% of the curable polymer P

[0055] In embodiments, the at least one curable polymer P comprises at least one thermoplastic polymer TP.

[0056] Suitable thermoplastic polymers for the curable polymer P include, for example, styrene-butadiene copolymers, styrene-isoprene copolymers, ethylene-vinyl acetate copolymers (EVA), olefin (meth)acrylate copolymers, olefin alkyl (meth)acrylate copolymers, olefin (meth)acrylic acid copolymers, polyolefins, and halogenated polyolefins, such as polyvinyl chloride (PVC).

[0057] Suitable olefin (meth)acrylate copolymers and olefin alkyl (meth)acrylate copolymers include, for example, ethylene-ethyl acrylate copolymers, ethylene-butyl acrylate copolymers (EBA), and ethylene-2-ethylhexyl acrylate copolymers.

[0058] The thermoplastic polymers TP may contain unsaturated olefinic bonds and they can also contain functional groups other than epoxide groups or acid anhydride groups, such as halogen, nitrile, thiol, hydroxyl, or carboxyl groups. It is however preferred that the at least one thermoplastic polymer TP is free of functional groups, which may interfere with the curing mechanism of the thermally expandable composition. This approach offers a better controllability of the curing mechanism and secondary properties such as the adhesion properties.

[0059] In embodiments, the at least one thermoplastic polymer TP is a non-functionalized thermoplastic polymer, preferably selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin alkyl (meth)acrylate copolymers, and olefin (meth)acrylic acid copolymers, more preferably from the group consisting of ethylenevinyl acetate copolymers, olefin (meth)acrylate copolymers, and olefin alkyl (meth)acrylate copolymers.

[0060] The at least one thermoplastic polymer TP may have: - a melt flow index determined according to ISO 1133 (190 °C / 2.16 kg) of not more than 200 g / 10 min, preferably not more than 175 g / 10 min, even more preferably not more than 155 g / 10 min and / or

[0061] - a melting point as determined by DSC measurements conducted according to ISO 11357-3 of at or below 125 °C, preferably at or below 110 °C, more preferably at or below 100 °C.

[0062] In exemplary embodiments, the at least one thermoplastic polymer TP comprises at least one first non-functionalized thermoplastic polymer TP1 and at least one second non-functionalized thermoplastic polymer TP2 different from the at least one first nonfunctionalized thermoplastic polymer TP1.

[0063] Generally, the expression “at least one compound X comprises at least one compound XN” is understood to mean that the composition comprises at least one compound XN as a representative of the at least one compound X.

[0064] The at least one first and second non-functionalized thermoplastic polymers TP1 and TP2 may be selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin alkyl (meth)acrylate copolymers, and olefin (meth)acrylic acid copolymers, particularly from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, and olefin alkyl (meth)acrylate copolymers.

[0065] The at least one first non-functionalized thermoplastic polymer TP1 may have melt flow index determined according to ISO 1133 (190 °C / 2.16 kg) of not more than 25 g / 10 min, such as not more than 15 g / 10 min, particularly not more than 10 min, especially 1 - 10 g / 10 min and / or the at least one second non-functionalized thermoplastic polymer TP2 may have a melt flow index determined according to ISO 1133 (190 °C / 2.16 kg) of at least 15 g / 10 min, such as at least 25 g / 10 min, particularly at least 30 g / 10 min, especially 25 - 200 g / 10 min.

[0066] In exemplary embodiments, the weight ratio of the amount of the at least one first non- functionalized thermoplastic polymer TP1 and the amount of the at least one second non-functionalized thermoplastic polymer TP2 is in the range of from 5:1 to 1 :3, particularly from 3:1 to 1 :2, especially from 2.5:1 to 1 :1. In embodiments, the at least one thermoplastic polymer TP is composed of the at least one first non-functionalized thermoplastic polymer TP1 and the at least one second non-functionalized thermoplastic polymer TP2, wherein the at least one first and second non-functionalized thermoplastic polymers TP1 and TP2 may be selected from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin alkyl (meth)acrylate copolymers, and olefin (meth)acrylic acid copolymers, particularly from ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers and olefin alkyl (meth)acrylate copolymers.

[0067] Solid rubbers

[0068] In embodiments, the curable polymer P comprises at least one solid rubber R.

[0069] The term “rubber” refers in the present disclosure to any natural, synthetic, or modified high molecular weight polymer or combination of polymers, which is capable of recovering from large deformations, i.e. has elastic properties. Typical rubbers are capable of being elongated or deformed to at least 200% of their original dimension under an externally applied force, and will substantially resume the original dimensions, sustaining only small permanent set (typically no more than about 20%), after the external force is released.

[0070] Particularly, the term “rubber” designates non-crosslinked rubbers, i.e., rubbers have not been chemically crosslinked to contain polymer chains that are inter-connected by a plurality of covalent bonds, which are mechanically and thermally stable.

[0071] Furthermore, the term “solid rubber” designates in the present disclosure rubbers that are solid at a temperature of 25°C.

[0072] In embodiments, the thermally expandable composition may comprise 5 - 35 wt.-%, preferably 7.5 - 30 wt.-%, more preferably 10 - 25 wt.-%, even more preferably 12.5

[0073] - 20 wt.-% of the solid rubber R. Suitable solid rubbers for use in the thermally expandable composition include, for example, 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.

[0074] In exemplary embodiments, the at least one solid rubber R is selected from 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.

[0075] Especially suitable solid rubbers have a number average molecular weight (Mn) determined by gel permeation-chromatography (GPC) using polystyrene as standard of at least 100000 g / mol, such as at least 125000 g / mol, particularly at least 150000 g / mol.

[0076] In embodiments, the at least one solid rubber R comprises at least one solid styrene- butadiene rubber R1.

[0077] The at least one solid styrene-butadiene rubber R1 may be an emulsion-polymerized styrene-butadiene rubber. These can be divided into two types, cold rubber and hot rubber depending on the emulsion polymerization temperature, but hot rubbers (hot type) are preferred.

[0078] The at least one solid styrene-butadiene rubber R1 may have a styrene content of 1 - 60 wt.-%, such as 2 - 50 wt.-%, particularly 10 - 40 wt.-%, especially15 - 40 wt-%, for example 20 - 35 wt.-%.

[0079] The at least one solid styrene-butadiene rubber R1 may further have a Mooney viscosity (ML 1 +4 at 100°C) of 25 - 150 MU (Mooney units), such as 30 -100 MU, particularly 35 -80 MU. The Mooney viscosity refers to the viscosity measure of rubbers. It is defined as the shearing torque resisting rotation of a cylindrical metal disk (or rotor) embedded in rubber within a cylindrical cavity. The dimensions of the shearing disk viscometer, test temperatures, and procedures for determining Mooney viscosity are defined in ASTM D1646 standard.

[0080] Especially suitable solid styrene-butadiene rubbers R1 include pre-crosslinked styrene-butadiene elastomers, which are commercially available, for example, under the trade name of Petroflex® SBR 1009A, 1009S and 1018 elastomers, manufactured by Petroflex / Lanxess, using either rosin or fatty acids soaps as emulsifier and coagulated by the salt-acid method, and SBR 1009, 1009A, 1502, and 4503 elastomers, manufactured by Lion Elastomers, by hot emulsion polymerization with divinylbenzene.

[0081] In embodiments, the at least one solid rubber R comprises at least one solid butyl rubber R2.

[0082] The term “butyl rubber” designates in the present document a polymer derived from a monomer mixture containing a major portion of a C4 to C? monoolefin monomer, preferably an isoolefin monomer and a minor portion, such as not more than 30 wt.- %, of a C4 to C14 multiolefin monomer, preferably a comjugated diolefin.

[0083] The preferred C4 to C7 monoolefin monomer may be selected from the group consisting of isobutylene, 2-methyl-1 -butene, 3-methyl-1 -butene, 2-methyl-2-butene, 4-methyl-1 -pentene, and mixtures thereof.

[0084] The preferred C4 to C14 multiolefin comprises a C4 to C10 conjugated diolefin. The preferred C4 to C10 conjugated diolefin may be selected from the group comprising isoprene, butadiene, 2,4-dimethylbutadiene, piperyline, 3-methyl-1 ,3-pentadiene, 2,4- hexadiene, 2-neopentyl-1 ,3-butadiene, 2-methyl-1 ,5-hexadiene, 2,5-dimethyl-2,4- hexadiene, 2-methyl-1 ,4-pentadiene, 2-methyl-1 ,6-heptadiene, cyclopentadiene, methylcyclopentadiene, cyclohexadiene, 1-vinyl-cyclohexadiene and mixtures thereof. Especially, the at least one solid butyl rubber R2 may be derived from a monomer mixture containing from about 80 wt.-% to about 99 wt.-% of a C4 to C? monoolefin monomer and from about 1.0 wt.-% to about 20 wt.-% of a C4 to C14 multiolefin monomer. More preferably, the monomer mixture contains from about 85 wt.-% to about 99 wt.-% of a C4 to C7 monoolefin monomer and from about 1 .0 wt.-% to about 10 wt.-% of a C4 to C14 multiolefin monomer. Most preferably, the monomer mixture contains from about 95 wt.-% to about 99 wt.-% of a C4 to C7 monoolefin monomer and from about 1 .0 wt.-% to about 5.0 wt.-%of a C4 to C14 multiolefin monomer.

[0085] Especially suitable solid butyl rubbers R2 are derived from a monomer mixture comprising from about 97 wt.-% to about 99.5 wt-% of isobutylene and from about 0.5 wt.-% to about 3 wt.-% of isoprene.

[0086] It is furthermore possible to include an optional third monomer to produce a butyl terpolymer. For example, it is possible to include a styrenic monomer in the monomer mixture, preferably in an amount up to about 15 wt.-% of the monomer mixture. The preferred styrenic monomer may be selected from the group comprising p- methylstyrene, styrene, a-methylstyrene, p-chlorostyrene, p-methoxystyrene, indene, indene derivatives and mixtures thereof. The most preferred styrenic monomer may be selected from the group comprising styrene, p-methylstyrene and mixtures thereof. Other suitable copolymerizable termonomers will be apparent to those of skill in the art.

[0087] The at least one solid butyl rubber R2 may have a Mooney viscosity (ML 1+8 at 125°C) of not more than 125 MU (Mooney units), such as not more than 100 MU, particularly not more than 85 MU.

[0088] In exemplary embodiments, the at least one solid butyl rubber R2 is a halogenated butyl rubber, preferably a chlorinated butyl rubber or a brominated butyl rubber, especially preferred a brominated butyl rubber.

[0089] Suitable halogenated butyl rubbers may comprise a halogen in an amount of at least 0.1 wt.-%, such as 0.1 - 10.0 wt.-%, for example 0.1 - 8.0 wt-%, especially 0.5 - 8.0 wt.-%, particularly 0.5 - 4.0 wt.-%, such as 1 .5 - 3.0 wt.-%, based on the weight of the butyl rubber.

[0090] In exemplary embodiments, the at least one solid butyl rubber R2 is a mixture of a solid halogenated butyl rubber and a solid non-halogenated butyl rubber, wherein the solid halogenated butyl rubber is preferably a brominated butyl rubber. In these embodiments the weight ratio of the amount of the solid halogenated butyl rubber and the amount of the solid non-halogenated butyl rubber may be in the range of 20 - 0.1 , more preferably 15 - 0.5, even more preferably 12.5 - 1 , most preferably 10 - 1.

[0091] In embodiments, the at least one solid rubber R comprises at least one solid polybutadiene rubber R3.

[0092] The term “polybutadiene rubber” designates in the present document a polymer obtained from the polymerization of the 1 ,3-butadiene monomer. Especially suitable solid polybutadiene rubbers have a 1 ,4 cis-bond content of at least 40 wt.-%, particularly greater than 80 wt.-%, especially greater than 95 wt.-%.

[0093] Furthermore, the at least one solid polybutadiene rubber R3 may have a Mooney viscosity (ML 1 +4 at 100°C) of 20 - 100 MU (Mooney units), particularly 25 - 80 MU, especially 30 - 60 MU.

[0094] In exemplary embodiments, the at least one solid rubber R is selected from the group consisting of the solid styrene-butadiene rubber R1 , the solid butyl rubber R2, and the solid polybutadiene rubber R3.

[0095] Epoxy-functional polymers

[0096] In embodiments, the curable polymer P comprises at least one epoxy-functional polymer EP, preferably having an average of more than one epoxy group per molecule. Particularly, the at least one epoxy-functional polymer EP may contain either polymerized or grafted epoxy functionality, i.e. the epoxide moieties may be present as part of a polymer backbone or grafted onto a polymer as a side chain.

[0097] Suitable epoxy-functional polymers for use in the curable polymer P include, for example, olefin glycidyl (meth)acrylate copolymers, olefin alkyl (meth)acrylate glycidyl (meth)acrylate terpolymers, glycidyl methacrylate grafted (co)polymers, epoxy resins, and epoxy-functionalized polyurethane polymers. The term "(meth)acrylate" designates in the present disclosure both acrylate and methacrylate.

[0098] Particularly suitable olefin glycidyl (meth)acrylate copolymers include, for example, copolymers of ethylene, propylene, or butylene with glycidyl acrylate (GA) or with glycidyl (meth)acrylate (GMA).

[0099] In embodiments, the at least one epoxy-functional polymer EP comprises at least one olefin glycidyl (meth)acrylate copolymer EP1 , preferably selected from the group consisting of ethylene glycidyl (meth)acrylate copolymers, propylene glycidyl (meth)acrylate copolymers, and butylene glycidyl (meth)acrylate copolymers, more preferably from the group consisting of ethylene glycidyl (meth)acrylate copolymers, in particular ethylene glycidyl methacrylate copolymers.

[0100] The at least one olefin glycidyl (meth)acrylate copolymer EP1 may have:

[0101] - a content of glycidyl methacrylate of 1 - 50 wt.-%, more preferably 2 - 25 wt.-% and / or

[0102] - a melt flow index, determined according to ISO 1133 (190 °C / 2.16 kg), of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min and / or

[0103] - a melting temperature (Tm) as determined by DSC measurements conducted according to ISO 11357-3 of at or below 150 °C, preferably at or below 135 °C, in particular in the range of 75 - 150 °C, preferably 85 - 135 °C, more preferably 90 - 125 °C. Suitable olefin alkyl (meth)acrylate glycidyl (meth)acrylate terpolymers include, for example, terpolymers, particularly random terpolymers of ethylene and alkyl (meth)acrylate with glycidyl acrylate (GA) orwith glycidyl methacrylate (GMA), wherein the alkyl group of the alkyl (meth)acrylate is preferably selected from methylene, ethylene, propylene, and butylene, in particular methylene or butylene.

[0104] Especially suitable olefin alkyl (meth)acrylate glycidyl (meth)acrylate terpolymers include ethylene methyl acrylate glycidyl acrylate terpolymers (E / MA / GA), ethylene ethyl acrylate glycidyl acrylate terpolymers (E / EA / GA), ethylene propyl acrylate glycidyl acrylate terpolymers (E / PA / GA), ethylene butyl acrylate glycidyl acrylate terpolymers (E / BA / GA), ethylene methyl methacrylate glycidyl acrylate terpolymers (E / MMA / GA), ethylene ethyl methacrylate glycidyl acrylate terpolymers (E / EMA / GA), ethylene propyl methacrylate glycidyl acrylate terpolymers (E / PMA / GA), ethylene butyl methacrylate glycidyl acrylate terpolymers (E / BMA / GA), ethylene methyl acrylate glycidyl methacrylate terpolymers (E / MA / GMA), ethylene ethyl acrylate glycidyl methacrylate terpolymers (E / EA / GMA), ethylene propyl acrylate glycidyl methacrylate terpolymers (E / PA / GMA), ethylene butyl acrylate glycidyl methacrylate terpolymers (E / BA / GMA), ethylene methyl methacrylate glycidyl methacrylate terpolymers

[0105] (E / MMA / GMA), ethylene ethyl methacrylate glycidyl methacrylate terpolymers

[0106] (E / EMA / GMA), ethylene propyl methacrylate glycidyl methacrylate terpolymers

[0107] (E / PMA / GMA), ethylene butyl methacrylate glycidyl methacrylate terpolymers

[0108] (E / BMA / GMA).

[0109] The at least one olefin alkyl acrylate glycidyl (meth)acrylate terpolymer EP2 may have:

[0110] - a content of glycidyl methacrylate of 1 - 50 wt.-%, more preferably 2 - 25 wt.-% and / or

[0111] - a melt flow index, determined according to ISO 1133 (190 °C / 2.16 kg), of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min and / or

[0112] - a melting temperature (Tm) as determined by DSC measurements conducted according to ISO 11357-3 of at or below 150 °C, preferably at or below 135 °C, in particular in the range of 75 - 150 °C, preferably 85 - 135 °C, more preferably 90 - 125 °C. Suitable glycidyl (meth)acrylate grafted (co)polymers include, for example, glycidyl methacrylate grafted olefin vinyl acetate copolymers, glycidyl methacrylate grafted ethylene-a-olefin copolymers, glycidyl methacrylate grafted propylene-a-olefin copolymers, glycidyl methacrylate grafted polyethylene, glycidyl methacrylate grafted polypropylene, and glycidyl methacrylate grafted olefin copolymer elastomers, glycidyl (meth)acrylate grafted styrene butadiene copolymers, and glycidyl (meth)acrylate grafted styrene ethylene butylene styrene terpolymers.

[0113] In exemplary embodiments, the at least one epoxy-functional polymer EP comprises at least one glycidyl methacrylate grafted (co)polymer EP3, preferably selected from the group consisting of glycidyl methacrylate grafted olefin vinyl acetate copolymers, glycidyl methacrylate grafted ethylene-a-olefin copolymers, glycidyl methacrylate grafted propylene-a-olefin copolymers, glycidyl methacrylate grafted polyethylene, glycidyl methacrylate grafted polypropylene, glycidyl (meth)acrylate grafted styrene butadiene copolymers, and glycidyl (meth)acrylate grafted styrene ethylene butylene styrene terpolymers.

[0114] The at least one glycidyl methacrylate grafted (co)polymer EP3 may have:

[0115] - a content of glycidyl methacrylate (GMA) of 0.1 - 10 wt.-%, preferably 0.1 - 5 wt.-%, more preferably 0.1 - 3.5 wt.-%, even more preferably 0.1 - 2.5 wt.-%, in particular 0.1 - 1.5 wt.-% and / or

[0116] - a melt flow index, determined according to ISO 1133 (190 °C / 2.16 kg), of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min and / or

[0117] - a melting temperature (Tm) as determined by DSC measurements conducted according to ISO 11357-3 of at or below 150 °C, preferably at or below 135 °C, in particular in the range of 75 - 150 °C, preferably 85 - 135 °C, more preferably 90 - 125 °C.

[0118] Suitable epoxy resins to be used as the at least one epoxy-functional polymer EP include solid and liquid epoxy resins having an average of more than one epoxy group per molecule and mixtures of these. The term “solid epoxy resin” designates epoxy resins having a glass transition temperature above the normal room temperature.

[0119] Suitable solid epoxy resins include those of the formula (VIII). wherein the substituents R’ and R” represent independently from one another either a hydrogen atom or a methyl group and the index s has a value of > 1 , preferably of > 1 .5, more preferably of 2 to 12.

[0120] Compounds of the formula (VIII) having an index s in the range from greater than 1 to 1 .5 are known to a person skilled in the art as semisolid epoxy resins. Forthe purposes of the present disclosure, these are likewise considered to be solid epoxy resins.

[0121] Suitable solid epoxy resins are commercially available, for example, from Dow Chemical Company, from Huntsman International LLC, from Hexion Specialty Chemicals Inc., and from Olin Corporation.

[0122] Suitable liquid epoxy resins which, in particular, can be used together with solid epoxy resins of formula (VIII), include those of formula (IX) wherein the substituents R’ and R” represent independent from one another either a hydrogen atom or a methyl group and the index r has a value of 0 to 1 , preferably a value of 0 to less than 0.2.

[0123] Preferred liquid epoxy resins are thus diglycidyl ethers of bisphenol A (DGEBA), of bisphenol F and of bisphenol A / F (the expression ‘A / F’ refers here to a mixture of acetone with formaldehyde which is used as a reactant in the preparation thereof).

[0124] Suitable liquid epoxy resins are commercially available, for example, under the trade names of Araldite® GY 250, Araldite® PY 304, and Araldite® GY 282 (from Huntsman International LLC), and under the trade names of D.E.R.® 331 or D.E.R.® 330 (from Dow Chemical Company), and under the trade names of Epikote® 828 or Epikote® 862 (from Hexion Specialty Chemicals Inc.).

[0125] Further suitable solid epoxy resins are so-called epoxy novolac resins. Particularly suitable epoxy novolac resins include those of formula (X) wherein the moiety X represents a hydrogen atom or a methyl group. The moiety W represents -CH2- or a moiety of the formula (X). Preferably, the index z has a value of 0 to 7, in particular a value of > 3. In particular, these are phenol or cresol novolacs (W represents -CH2-).

[0126] Such epoxy novolac resins are commercially available, for example, under the trade names of EPN®, ECN®, and Tactix® 556 (from Huntsman International LLC) and under the trade name of D.E.N® (from Dow Chemical Company).

[0127] In embodiments, the at least one epoxy-functional polymer EP comprises or is composed of at least one epoxy resin EP4, preferably selected from solid epoxy resin of formula (VIII), solid epoxy resin of formula (X), and mixtures of solid epoxy resin of formula (VIII) and / or (X) with liquid epoxy resin of formula (IX). The thermally expandable compositions according to these embodiments are particularly suitable for use as structural foams, in particular for use in reinforcing of hollow structures.

[0128] Further suitable epoxy resins to be used as the at least one epoxy-functional polymer EP include epoxy-functional polyurethane polymers of formula (XII) wherein Y represents a w-valent radical of a linear or branched isocyanate-functional polyurethane polymer PU after the removal of the w terminal isocyanate groups;

[0129] Z represents a (1+v)-valent radical of an aliphatic, cycloaliphatic, aromatic or aral aliphatic epoxide E containing a primary or secondary hydroxyl group after the removal of the hydroxyl group and v epoxide groups; v represents an integer with a value of 1 , 2, or 3, preferably 2; and w represents an integer with a value from 2 to 4. The linear or branched isocyanate-functional polyurethane polymer PU has preferably a structure according to formula (XIII) wherein Y and w have the same meaning as described further above.

[0130] The isocyanate-functional polyurethane polymer PU, represented in formula (XIII), may be obtained from the reaction of at least one polyisocyanate, preferably diisocyanate or triisocyanate, with at least one polyol, wherein the isocyanate groups are in stoichiometric excess over hydroxyl groups. The reaction can be carried out via known methods, preferably at temperatures of between 50 and 150 °C, optionally in the presence of a catalyst.

[0131] Suitable polyols for the production of isocyanate-functional polyurethane polymer PU include, for example, polyoxyalkylene polyols, also referred to as polyether polyols, which are the polymerization product of ethylene oxide, 1 ,2-propylene oxide, 1 ,2- or 2,3-butylene oxide, tetrahydrofuran or mixtures thereof, optionally polymerized by means of a starter molecule with two or three active H atoms such as water or compounds with two or three OH groups, for example ethylene glycol or glycerol.

[0132] Preferred polyether polyols are polymerization products of ethylene oxide, 1 ,2- propylene oxide, 1 ,2- or 2,3-butylene oxide, tetrahydrofuran or mixtures thereof, particularly preferable being polypropylene oxides and polytetrahydrofurans. Suitable polytetrahydrofurans are commercially available, for example, from BASH under the trade names of PolyTHF®, for example PolyTHF®2000, PolyTHF®2500 CO, and PolyTHF®3000 CO. Suitable polypropylene oxides are commercially available, for example, from Shell under the trade name of Caradol®, such as Caradol®2000 and Caradol®ED56 and from Bayer under the trade name of Acclaim®, such as Acclaim® Polyol 2200, Acclaim® Polyol 12200, and Acclaim® Polyol 4200. Further suitable polyether polyols are commercially available from Dow Chemicals under the trade names of Voranol®1010L, Voranol® EP1900, and Voranol®CP4755.

[0133] Especially preferred polyether polyol is polytetrahydrofuran. Preferred polyether polyols have, for example, a weight average molecular weight (Mw) determined by gel permeation-chromatography (GPC) using polystyrene as standard in the range from 500 to 5000 g / mol, more preferably 1000 to 3000 g / mol and particularly preferably in the range from 1500 to 2500 g / mol.

[0134] The OH-functionality of the polyether polyols used is preferably in the range of approximately 2, for example, in the range from 1.9 to 2.1. Optionally, a compound with an OH functionality of 3, such as, for example, trimethylolpropane, butoxylated trimethylolpropane (for example, Simulsol®TOMB), and / or pentaerythritol can be added to the polyether polyol in order to increase the OH functionality.

[0135] Furthermore suitable polyols include hydroxyl-terminated rubbers. One or more OH- terminated rubbers can be used, wherein the use of two OH-terminated rubbers, in particular two OH-terminated polybutadienes, are preferred. Here, OH-terminated rubbers are understood to refer, for example and preferably, to hydroxyl-terminated polybutadienes and to castor oil-based polyols, wherein hydroxyl-terminated polybutadienes are particularly preferable. Polyols based on castor oil include castor oil of various grades and castor oil derivatives.

[0136] Commercially available hydroxyl-terminated polybutadienes are commercially available, for example, from Cray valley under the trade names of Poly bd® and Krasol®, such as Krasol® LBH-P 2000 or Poly bd® R45V; from Evonik under the trade name of Polyvest® HT; from Emerald materials under the trade name of Hypro® 2800X95 HTB. Castor oil-based polyols are commercially available, for example, Alberdingk Boley under the trade name of Albodur®; from Baker Castor Oil Company under the trade name of Polycine®, such as Polycine®-GR80.

[0137] The OH-functionality of the hydroxyl-terminated rubbers is preferably in the range from 1 .7 to 2.2 for anionically produced types or from 2.2 to 2.8 for types produced by free radical polymerization. Also suitable as polyols are polyhydroxy-terminated acrylonitrile / butadiene copolymers, for example, the ones prepared using carboxyl-terminated acrylonitrile / butadiene copolymers, such as the ones, which are commercially available from Emerald Materials under the trade names of Hypro® CTBN, as well as the ones prepared using epoxides or amino alcohols.

[0138] Furthermore suitable polyols for the production of isocyanate-functional polyurethane polymer PU include polyester polyols prepared, for example, from dihydric to trihydric alcohols such as, for example, 1 ,2-ethanediol, diethylene glycol, 1 ,2-propanediol, dipropylene glycol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6-hexanediol, neopentylglycol, glycerol, 1 ,1 ,1 -trimethylolpropane or mixtures of the aforementioned alcohols, with organic dicarboxylic acids or their anhydrides or esters, such as, for example, succinic acid, glutaric acid, adipic acid, suberic acid, sebacic acid, dodecanedicarboxylic acid, maleic acid, fumaric acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydrophthalic acid, or mixtures of the aforementioned acids, and also polyester polyols from lactones such as £-caprolactone.

[0139] Suitable as polyols for the production of isocyanate-functional polyurethane polymer PU are furthermore polycarbonate polyols of the kind obtainable by reacting, for example, the abovementioned alcohols, i.e. those used to synthesize the polyester polyols, with dialkyl carbonates, diaryl carbonates or phosgene. Also suitable are polyols of the kind obtained by reduction of dimerized fatty acids.

[0140] The isocyanate-functional polyurethane polymer PU may be obtained by using only one type of polyol. Preferred polyols for these embodiments are polyether polyols, in particular polytetrahydrofuran. It may however be advantageous to use a mixture of different types of polyols for the production of the polyurethane polymer PU. According to one or more embodiments, the isocyanate-functional polyurethane polymer PU comprises is obtained by using a polyether polyol, in particular polytetrahydrofuran, and a polybutadiene polyol.

[0141] Suitable polyisocyanates for the production of the isocyanate-functional polyurethane polymer PU include diisocyanates and triisocyanates. Suitable diisocyanates are aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, in particular those, m which are commercially available, such as methylene diphenyl diisocyanate (MDI), hexamethylene diisocyanate (HDI), toluene diisocyanate (TDI), toluidine diisocyanate (TODI), isophorone diisocyanate (IPDI), trimethyl hexamethylene diisocyanate (TMDI), 2,5- or 2,6-bis(isocyanatomethyl)-bicyclo[2.2.1]heptane, 1 ,5-naphthalene diisocyanate (NDI), dicyclohexyl methyl diisocyanate (H12MDI), p-phenylene diisocyanate (PPDI), m-tetramethyl xylylene diisocyanate (TMXDI), as well as their dimers, wherein HDI, IPDI, MDI, TDI are preferred. Particularly preferable diisocyanates are aliphatic and cycloaliphatic diisocyanates, for example, HDI, H12MDI and IPDI.

[0142] Suitable triisocyanates are trimers or biurets of aliphatic, cycloaliphatic, aromatic or araliphatic diisocyanates, in particular the isocyanurates and biurets of the diisocyanates described above.

[0143] The isocyanate-functional polyurethane polymer PU is then end-capped with at least one monohydroxyl epoxide compound E according to formula (XIV) wherein Z and v have the same meaning as described above.

[0144] The monohydroxyl epoxide compound E of formula (XIV) is an aliphatic, cycloaliphatic, aromatic, or aral aliphatic epoxide containing one single primary or secondary hydroxyl group and from 1 to 3 epoxide groups.

[0145] The monohydroxyl epoxide compounds E of formula (XIV) can be obtained, for example, by reacting polyols with epichlorohydrin. Depending on the reaction regime, the reaction of polyols with epichlorohydrin produces by-products including the corresponding monohydroxyl epoxide compounds in different concentrations. These can be isolated by routine separation operations. Generally speaking, however, it is sufficient to use the product mixture obtained in the glycidylization reaction of polyols, comprising fully reacted polyol and polyol which has reacted partially to form the glycidyl ether. Examples of hydroxyl-containing epoxide compounds of this kind are butanediol monoglycidyl ether (contained in butanediol diglycidyl ether), hexanediol monoglycidyl ether (contained in hexanediol diglycidyl ether), cyclohexanedimethanol glycidyl ether, trimethylolpropane diglycidyl ether (contained as a mixture in trimethylolpropane triglycidyl ether), glycerol diglycidyl ether (contained as a mixture in glycerol triglycidyl ether), pentaerythritol triglycidyl ether (contained as a mixture in pentaerythritol tetraglycidyl ether). It is preferred to use trimethylolpropane diglycidyl ether, which occurs at a relatively high fraction in customarily prepared trimethylolpropane triglycidyl ether.

[0146] It is, however, also possible to use other, similar hydroxyl-containing epoxides, especially glycidol, 3-glycidyloxybenzyl alcohol or hydroxymethylcyclohexene oxide. Further preference is given to the liquid epoxy resins of formula (IX) as described above.

[0147] Preference for end-capping the isocyanate-functional polyurethane polymer PU extends to distillation residues which are obtained in the preparation of high-purity, distilled liquid epoxy resins. Distillation residues of this kind have a concentration of hydroxyl-containing epoxides which is up to three times higher than that of commercial undistilled liquid epoxy resins. Such resins are commercially available, for example under the trade name of Epilox® M850 from Leuna-Harze. Furthermore, it is also possible to use a wide variety of epoxides containing a -hydroxy ether group, prepared by the reaction of (poly)epoxides with a substoichiometric amount of monofunctional nucleophiles such as carboxylic acids, phenols, thiols or secondary amines.

[0148] In embodiments, the at least one epoxy-functional polymer EP comprises or is composed of at least one epoxy-functional polyurethane polymer EP5, preferably at least one epoxy-functional polyurethane polymer of formula (XII).

[0149] In exemplary embodiments, the curable polymer P comprises the at least one olefin glycidyl (meth)acrylate copolymer EP1 and / or the at least one olefin alkyl acrylate glycidyl (meth)acrylate terpolymer EP2 and / or the at least one glycidyl (meth)acrylate grafted (co)polymer EP3.

[0150] Acid anhydride-functional polymers

[0151] In embodiments, the curable polymer P comprises at least one acid anhydride- functional polymer AP, preferably having an average of more than one acid anhydride group per molecule.

[0152] Furthermore, the at least one acid anhydride-functional polymer AP may contain either polymerized or grafted acid anhydride functionality, i.e. the acid anhydride moieties may be present as part of a polymer backbone or grafted onto a polymer as a side chain.

[0153] Suitable acid anhydride-functional polymers AP include maleic anhydride-functional polymers and tetrahydrophthalic anhydride-functional polymers, particularly maleic anhydride-functional polymers. Suitable maleic anhydride-functional polymers include, for example, olefin maleic anhydride copolymers, olefin alkyl (meth)acrylate maleic anhydride terpolymers, and maleic anhydride grafted (co)polymers.

[0154] Especially suitable olefin alkyl acrylate maleic anhydride terpolymers include, for example, terpolymers in particular random terpolymers of ethylene and alkyl (meth)acrylate, and maleic anhydride, wherein the alkyl group of the alkyl (meth)acrylate is preferably selected from methylene, ethylene, propylene, and butylene.

[0155] In embodiments, the at least one acid anhydride-functional polymer AP comprises at least one olefin alkyl acrylate maleic anhydride terpolymer AP1 , preferably selected from random terpolymers of ethylene, alkyl (meth)acrylate, and maleic anhydride, wherein the alkyl group of the alkyl (meth)acrylate is preferably selected from methylene, ethylene propylene, and butylene, more preferably methylene, ethylene, and butylene. The at least one olefin alkyl acrylate maleic anhydride terpolymer AP1 may have:

[0156] - a content of maleic anhydride of 0.5 - 10 wt.-%, preferably 1 - 7.5 wt.-%, more preferably 1 - 5 wt.-% and / or

[0157] - a melt flow index, determined according to ISO 1133 (190 °C / 2.16 kg), of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min and / or

[0158] - a melting temperature (Tm) as determined by DSC measurements conducted according to ISO 11357-3 of at or below 150 °C, preferably at or below 135 °C, in particular in the range of 75 - 150 °C, preferably 85 - 135 °C, more preferably 90 - 125 °C.

[0159] Suitable olefin maleic anhydride copolymers include, for example, copolymers of maleic anhydride with ethylene, propylene, or butylene.

[0160] In embodiments, the at least one acid anhydride-functional polymer AP comprises at least one olefin maleic anhydride copolymer AP2, preferably selected from copolymers of ethylene, propylene, and butylene with maleic hydride, more preferably ethylene maleic anhydride copolymers.

[0161] Particularly suitable maleic anhydride grafted (co)polymers include, for example, maleic anhydride grafted olefin alkyl (meth)acrylate copolymers, maleic anhydride grafted olefin vinyl acetate copolymers, maleic anhydride grafted ethylene-a-olefin copolymers, maleic anhydride grafted propylene-a-olefin copolymers, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, and maleic anhydride grafted olefin copolymer elastomers, such as maleic anhydride grafted ethylene-propylene rubber (EPR).

[0162] In embodiments, the at least one acid anhydride-functional polymer AP comprises at least one maleic anhydride grafted (co)polymer AP3, preferably selected from maleic anhydride grafted olefin alkyl (meth)acrylate copolymers, maleic anhydride grafted olefin vinyl acetate copolymers, maleic anhydride grafted ethylene-a-olefin copolymers, maleic anhydride grafted propylene-a-olefin copolymers, maleic anhydride grafted polyethylene, maleic anhydride grafted polypropylene, and maleic anhydride grafted olefin copolymer elastomers, more preferably from maleic anhydride grafted olefin vinyl acetate copolymers, maleic anhydride grafted polyethylene, and maleic anhydride grafted polypropylene.

[0163] The at least one maleic anhydride grafted (co)polymer AP3 may have:

[0164] - a content of maleic anhydride of 0.1 - 10 wt.-%, preferably 0.1 - 5 wt-%, more preferably 0.1 - 3.5 wt.-%, even more preferably 0.1 - 2.5 wt.-%, in particular 0.1 - 1.5 wt.-% and / or

[0165] - a melt flow index, determined according to ISO 1133 (190 °C / 2.16 kg), of not more than 100 g / 10 min, preferably not more than 75 g / 10 min, more preferably not more than 50 g / 10 min and / or

[0166] - a melting temperature (Tm) as determined by DSC measurements conducted according to ISO 11357-3 of at or below 150 °C, preferably at or below 135 °C, in particular in the range of 75 - 150 °C, preferably 85 - 135 °C, more preferably 90 - 125 °C.

[0167] In exemplary embodiments, the at least one acid anhydride-functional polymer AP comprises the at least one olefin alkyl acrylate maleic anhydride terpolymer AP1 and / or the at least one olefin maleic anhydride copolymer AP2 and / or the at least one maleic anhydride grafted (co)polymer AP3.

[0168] In embodiments, the curable polymer P is composed of the at least one thermoplastic polymer TP.

[0169] In further embodiments, the curable polymer P comprises or is composed of the at least one epoxy-functional polymer EP and the at least one acid anhydride-functional polymer AP, wherein the weight ratio of the epoxy-functional polymer EP to the acid anhydride-functional polymer AP is preferably in the range of from 0.3:1 to 3:1 , more preferably from 0.5:1 to 2:1. In still further embodiments, the curable polymer P comprises or is composed of the at least one thermoplastic polymer TP, the at least one epoxy-functional polymer EP and / or the at least one acid anhydride-functional polymer AP, wherein the curable polymer P particularly comprises at least 35 wt.-%, especially at least 50 wt.-%, especially at least 65 wt.-% of the at least one thermoplastic polymer TP.

[0170] The thermally expandable composition may further comprise at least one free radical initiator I.

[0171] All types of free radical initiators that that are known to undergo decomposition upon exposure to sufficient amount of energy, such as radiation, heat, or the like to generate radicals capable of initiating the desired curing (crosslinking) reactions are in principle considered suitable for use as the free radical initiator I.

[0172] In embodiments, the at least one free radical initiator I is an azo-initiator Al, preferably selected from the group consisting of azonitrile compounds, alkylazo compounds, and azoamide compounds.

[0173] Although some of the compounds used in the present invention are characterized as useful for specific functions, it should be understood that the use of these compounds is not limited to their typical functions. For example, the at least one azo initiator Al may serve not only as a free radical initiator for the cross-linking reactions, but also as a blowing agent for a foaming process.

[0174] Suitable azo initiators are essentially inert at normal room temperature (23 °C) and exhibit an activation temperature suitable for the intended purpose. For example, in case the thermally expandable composition is used for providing a baffle and / or reinforcement element in automotive manufacturing, an activation temperature in the range of 90 - 250 °C is typically preferred. Furthermore, it is advantageous that the at least one azo initiator Al has an activation temperature compatible with the decomposition temperature of the at least one chemical blowing agent BA. If the above mentioned two temperatures differ too much, it may be more difficult to obtain a thermally expandable composition with optimal performance and stability. It may furthermore be advantageous for the at least one azo initiator Al to have a halflife of 10 h at a temperature in the range of 55 C - 120°C, as measured in toluene or in a similar non-polar solvent. For certain types of azo initiators, other solvents than toluene may be more suitable for use in measurement of the half-life, such as substituted (for example, chlorinated) benzene, methanol, or water. The choice of the suitable solvent depends mainly on the solubility of the azo initiator in the respective solvent. It may furthermore be advantageous that the at least one azo initiator Al is compatible and / or miscible with the curable polymer P of the thermally expandable composition. In some cases the compatibility of the azo initiator with the curable polymer P can be further improved by using processing aids and other compatibilizing additives.

[0175] Suitable azo initiators Al include, for example, 4,4’-azobis(4-cyanovaleric acid), 1 ,1’- azobis(cyclohexane-l-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],

[0176] In exemplary embodiments, the at least one azo initiator Al 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],

[0177] In embodiments, the thermally expandable composition may comprise 0.1 - 10 wt.-%, such as 0.15 - 7.5 wt.-%, particularly 0.25 - 5 wt.-%, especially 0.25 - 3.5 wt.-% of the at least one azo initiator Al.

[0178] Other free radical initiators, such as peroxide initiators, are also suitable for use as the at least one free radical initiator I. In embodiments, the at least one free-radical initiator I is a peroxide initiator PI. It may furthermore be possible that the thermally expandable composition comprises multiple different types of free radical initiators, for example, the at least one azo-initiator Al and the at least one peroxide initiator PI. Use of different free radical initiators may, however, not be preferred, although possible.

[0179] Suitable peroxide initiators PI are essentially inert at room temperature (23 °C) and exhibit an activation temperature suitable for the intended purpose. For example, if the thermally expandable composition is to be used for providing a baffle and / or reinforcement element in automotive manufacturing, an activation temperature of in the range of 90 - 250 °C is typically preferred. Furthermore, it may be advantageous that the at least one peroxide initiator PI has an activation temperature compatible with the decomposition temperature of the at least one chemical blowing agent BA. If the above mentioned two temperatures differ too much, it may be more difficult to obtain a thermally expandable composition with optimal performance and stability.

[0180] It may furthermore be advantageous that the at least one peroxide initiator PI has a half-life of 10 h at a temperature in the range of 90 - 130 °C, as measured in benzene or in a similar non-polar solvent. For certain types of peroxide initiators other solvents than benzene may be more suitable for use in measurement of the half-life, such as, for example, toluene, triethyl phosphate or dibutyl phthalate. For ultra-low temperature embodiments, i.e. those optimized for expansion between 120 °C and 150 °C, peroxide initiators having a half-life of 10 h at temperatures in the range of 50 - 100 °C are preferred. It is furthermore advantageous that the at least one peroxide initiator PI is compatible and / or miscible with the curable polymer P of the thermally expandable composition. In some cases the compatibility of the peroxide initiator with the curable polymer P can be further improved by using processing aids and other compatibilizing additives.

[0181] Suitable peroxide initiators include, in particular organic peroxides. All types of organic peroxides that are known to undergo decomposition by heat to generate radicals capable of initiating the desired curing (crosslinking) reactions are in principle considered suitable for use as the at least one peroxide initiator PI. In exemplary embodiments, the at least one peroxide initiator PI is an organic peroxide, preferably selected from keton peroxides, diacyl peroxides, peresters, perketals, and hydroperoxides. Examples of preferred peroxides include cumene hydroperoxide, t-butyl peroxide, bis(t-butylperoxy)-diisopropyl benzene, di(t- butylperoxy isopropyl) benzene, dicumyl peroxide, t-butylperoxy benzoate, dialkylperoxy dicarbonate, diperoxyketals (such as 1 , 1 -di-t-butylperoxy-3,3,5-trimethyl cyclohexane), keton peroxides (such as methyl ethyl keton peroxide), and 4,4-di-t- butylperoxy-n-butyl valerate.

[0182] Particularly suitable organic peroxides include 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-butylperoxy isopropyl) benzene, dicumyl peroxide, butyl-4,4-di(t-butylperoxy) valerate, t- butylperoxy-2-ethylhexyl carbonate, 1 , 1 -di(t-butylperoxy)-3,3,5-trimethyl cyclohexane, t-butylperoxy benzoate, di(4-methylbenzoyl) peroxide, and dibenzoyl peroxide.

[0183] In embodiments, the at least one peroxide 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-trimethyl cyclohexane.

[0184] These are commercially available, for example, under the trade names of Perkadox® BC-40B-PD from Akzo Nobel and Peroxan® DC-40 PK from Pergan (dicumyl peroxide); under the trade names of Perkadox® 14-40B-PD Akzo Nobel and Peroxan® BIB-40 P from Pergan (di(t-butylperoxyisopropyl) benzene); and under the trade name of Peroxan® PK295 from Pergan (di(t-butylperoxyisopropyl) benzene).

[0185] In embodiments, the thermally expandable composition comprises 0.05 - 10 wt.-%, such as 0.1 - 7.5 wt.-%, particularly 0.1 - 5 wt.-%, especially 0.15 - 3.5 wt.-% of the at least one peroxide initiator PI.

[0186] It may furthermore be advantageous that the at least one peroxide initiator PI is present in the thermally expandable composition as immobilized on a support material, such as silica, kaolin, and / or calcium carbonate, or other suitable materials. This approach may facilitate handling, dosage, and evenly distribution of the at least one peroxide initiator PI in the thermally 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-trimethyl cyclohexane on calcium carbonate. In these embodiments, the expression “the amount of the at least one peroxide initiator PI” refers to the amount of the active substance contained in the thermally expandable composition excluding the amount of the support material on which the at least one peroxide initiator PI, for example, an organic peroxide, has been immobilized.

[0187] In embodiments, the thermally expandable composition further comprises at least one co-agent CA comprising at least two (meth)acryloyl groups. The term “(meth)acryloyl” designates in the present disclosure both acryloyl and methacryloyl.

[0188] In exemplary embodiments, the at least one co-agent CA2 is a multi-functional acrylate, preferably having a molecular weight of less than 2500 g / mol, more preferably less than 1000 g / mol and / or an acrylate functionality of at least 2 or 3, preferably at least 4 or 5, or more.

[0189] Such multifunctional acrylates can improve the cross-linking of the curable polymers contained in the curable polymer P and aid in obtaining a stable foam structure. The at least one co-agent CA, if used, may make up 0.01 - 3.5 wt.-%, such as preferably 0.025 - 2.5 wt.-%, particularly 0.025 - 1.5 wt.-%, especially 0.05 - 1.0 wt.-% of the total weight of the thermally expandable composition.

[0190] Suitable acrylates with a functionality of 2 include, for example, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, triethylene glycol diacrylate, tripropylene glycol dimethacrylate, 1 ,3-butanediol dimethacrylate, 1 ,4-butanediol dimethacrylate, 1 ,10-dodecanediol dimethacrylate, 1 ,6-hexandieol dimethacrylate, neopentylglycol dimethacrylate, and polybutylene glycol dimethacrylate, and hexanediol diacrylate.

[0191] Suitable acrylates with a functionality of 3 or higher include, for example, glycerol triacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetraacrylate, Di-(trimethylolpropane) tetraacrylate, pentraerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tri(2-methacryloxyethyl) trimellitate, tri(2-acryloxyethyl) isocyanurate, as well as their ethoxylated or propoxylated derivates. Most preferred multifunctional acrylate with functionality of 5 is dipentaerythritol pentaacrylate. Furthermore suitable are highly functional, hyperbranched acrylates with functionalities of between 6 and 16, or higher. Examples of such acrylates include hyperbranched polyesterpolyacrylates.

[0192] In embodiments, the sum of the amounts of the at least one free radical initiator I, the at least one co-agent CA, if present in the thermally expandable composition, makes up 0.5 - 10 wt.-%, such as 1.0 - 7.5 wt.-%, particularly 1.25 - 6.5 wt.-%, especially 1 .25 - 5 wt.-% of the total weight of the thermally expandable composition.

[0193] In embodiments, the thermally expandable composition is substantially free of solid epoxy resins of formula (VIII), liquid epoxy resins of formula (IX), and solid epoxy resins of formula (X).

[0194] The expression “substantially free of” is understood to mean that the total amount of the specified epoxy resins in the thermally expandable composition is not more than 1 .5 wt.-%, preferably not more than 1 .0 wt.-%, more preferably not more than 0.5 wt.- %, even more preferably not more than 0.25 wt.-%, particularly not more than 0.1 wt.- %, based on the total weight of the thermally expandable composition. The thermally expandable compositions according to these embodiments may be particularly suitable for use in sealing and baffling of hollow structures.

[0195] Apart from the essential and optional ingredients listed above, the thermally expandable composition may contain other compounds commonly used in such compositions and known to the ordinarily person skilled in the art. These include, for example, tackifying resins, fillers, colorants, dispersion aids or homogenizers, stabilizers, and the like.

[0196] The term “tackifying resin” designates in the present document resins that in general enhance the adhesion and / or tackiness of a composition. The term “tackiness” refers in the present document to the property of a substance of being sticky or adhesive by simple contact, which can be measured, for example, as a loop tack. Preferred tackifying resins are tackifying at a temperature of 25 °C. Such tackifying resins lead to good adhesion on metal substrates, especially oiled metal substrates, both before and after foaming of the thermally expandable composition.

[0197] Suitable tackifying resins to be used in the thermally expandable composition have a relatively low average molecular weight (Mn), such as not more than 5000 g / mol, in particular not more than 3500 g / mol, preferably not more than 2500 g / mol and a softening point, determined by a Ring and Ball method according to DIN EN 1238, of at or below 180 °C, preferably at or below 160 °C, more preferably at or below 150 °C. Suitable tackifying resins include, in particular, synthetic resins, natural resins, and chemically modified natural resins.

[0198] The term “synthetic resin” designates in the present disclosure compounds obtained from the controlled chemical reactions such as polyaddition or polycondensation between well-defined reactants that do not themselves have the characteristic of resins. Monomers that may be polymerized to synthesize the synthetic resins may include aliphatic monomer, cycloaliphatic monomer, aromatic monomer, or mixtures thereof. Suitable aliphatic monomers may include C4, Cs, and Ce paraffins, olefins, and conjugated diolefins. Examples of aliphatic monomers or cycloaliphatic 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 monomer include Cs, C9, and C10 aromatic monomers. Typical aromatic monomers include, styrene, alphamethyl styrene, vinyl toluene, methoxy styrene, tertiary butyl styrene, chlorostyrene, coumarone, and indene monomers including indene, and methyl indene, and combinations thereof.

[0199] Suitable synthetic resins include, for example, hydrocarbon resins, coumarone-indene resins, polyindene resins, polystyrene resins, vinyl toluene-alphamethyl styrene copolymer resins, and alphamethyl styrene resins.

[0200] The term “hydrocarbon resin” designates in the present disclosure synthetic resins made by polymerizing mixtures of unsaturated monomers obtained from petroleum based feedstocks, such as by-products of cracking of natural gas liquids, gas oil, or petroleum naphthas. These types of hydrocarbon resins are also known as “petroleum resins” or as “petroleum hydrocarbon resins”. The hydrocarbon resins include also pure monomer aromatic resins, which are prepared by polymerizing aromatic monomer feedstocks that have been purified to eliminate color causing contaminants and to precisely control the composition of the product.

[0201] Suitable hydrocarbon resins are commercially available, for example, under the trade name of Wingtack®, Wingtack® Plus, Wingtack® Extra, and Wingtack® STS (all from Cray Valley); under the trade name of Escorez® 1000 series, Escorez® 2000 series, and Escorez® 5000 series (all from ExxonMobil Chemical); under the trade name of Novares® T series, Novares® TT series, Novares® TD series, Novares® TL series, Novares® TN series, Novares® TK series, and Novares® TV series (all from RUTGERS Novares GmbH); and under the trade name of Kristalex®, Plastolyn®, Piccotex®, Piccolastic® and Endex® (all from Eastman Chemicals).

[0202] Tackifying resins, if used, may be present in the thermally expandable composition in an amount of 2 - 20 wt.-%, such as 4 - 15 wt.-%, particularly 5 - 10 wt.-%, based on the total weight of the thermally expandable composition.

[0203] Suitable fillers to be used in the thermally expandable composition include, for example, ground or precipitated calcium carbonate, lime, calcium-magnesium carbonate, talcum, gypsum, graphite, barite, pyrogenic or precipitated silica, silicates, 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 alumoxanes, and carbon black. Suitable fillers include both organically coated and also uncoated commercially available forms of the fillers included in the above presented list. Particularly suitable fillers include ground or precipitated calcium carbonate, calcium-magnesium carbonate, talcum, gypsum, graphite, barite, pyrogenic or precipitated silica, silicates, mica, wollastonite, carbon black, and mixtures thereof. Fillers, if used, preferably make up 1 - 20 wt.-%, more preferably 1 - 15 wt.-%, even more preferably 2.5 - 15 wt.-% of the total weight of the thermally expandable composition.

[0204] Colorants or dyes, such as pigments, for example on the basis of carbon black, may also be included in the thermally expandable composition. Their amount is preferably between 0.1 - 1 wt.-%, based on the total weight of the thermally expandable composition.

[0205] Preferably, the thermally expandable composition after curing has a volume increase compared to the uncured composition of at least 100 %, preferably at least 150 %, more preferably at least 250 %, whereby the volume increase is determined using the DIN EN ISO 1183 method of density measurement (Archimedes principle) in deionised water in combination with sample mass determined by a precision balance.

[0206] In exemplary embodiments, the thermally expandable composition after curing has a volume increase compared to the uncured composition in the range of 100 - 3000 %, preferably 150 - 2500 %, more preferably 250 - 2000 %, even more preferably 250 - 1750 %.

[0207] The thermally expandable compositions according to the present invention can be produced by mixing the constituents in any suitable mixing apparatus, for example in a dispersion mixer, planetary mixer, such as planetary roller, extruder such as a twin screw extruder, kneader, such as a Buss, Banbury, or roller kneader, or a two-roll mill.

[0208] It may be advantageous to heat the constituents before or during mixing, either by applying external heat sources or by friction generated by the mixing process itself, in order to facilitate processing of the components into a homogeneously mixed mixture by decreasing viscosities and / or melting of individual components. However, care has to be taken, for example by temperature monitoring and using cooling devices where appropriate, not to exceed the activation temperatures of the at least one polymeric blowing agent BA and of the at least one free radical initiator I, if present. The thus obtained thermally expandable composition is preferably essentially solid at normal room temperature (23 °C), meaning that it does not visibly deform at this temperature just by means of gravity during a period of at least 24 h.

[0209] After mixing of the constituents of the thermally expandable composition, the thus obtained composition may be shaped into its desired form by, for example, extruding, blow-molding, pelleting, injection molding, compression molding, punching, or stamping or using any other suitable process.

[0210] The thermally expandable composition of the present invention may be produced in a substantially one-step process, involving the addition of all constituents in a series and / or simultaneously. However, it may also be advantageous to provide the thermally expandable composition as a two-part system, or even multipart system. In these cases, the constituents of the thermally expandable composition are provided in separate air- and moisture impermeable packages or compartments of a single package and they are mixed with each other and optionally with other compounds at the time of use or immediately before the time of use of the thermally expandable composition. Such an approach may, for example, be taken to increase shelf life of the thermally expandable composition in places with demanding conditions (such as extraordinarily high temperatures), to optimize storage room demand and transport weight, or to enable providing tailor-made, modular compositions for different applications.

[0211] The thermally expandable compositions according to the present invention are storage stable at normal storage conditions. The term “storage stable” refers in the present disclosure to materials, which can be stored at specified storage conditions for long periods of time, such as at least one month, in particular at least 3 months, without any significant changes in the application related properties of the material. The “typical storage conditions” refer here to temperatures of not more than 60°C, in particular not more than 50°C.

[0212] The expansion of the thermally expandable composition of the present invention is triggered by heating. This means that the thermally expandable composition is activated by a heating step that exceeds its activation temperature and exhibits a duration long enough for the decomposition of the at least one polymeric blowing agent BA (resulting in gas formation) to proceed until the expandable material has expanded and cured into its intended final (sufficiently expanded and stable) state. The optimal temperature and duration of the heating step (dwell time) depends on the embodiment of the thermally expandable composition, in particular on the composition of the at least one polymeric blowing agent BA and the at least one free radical initiator I, if present in the thermally expandable composition. The thermally expandable composition may have an activation temperature in the range of 120 - 250 °C, preferably 140 - 220 °C, and a dwell time of the heating step in the range of 5 - 90 min, preferably 10 - 60 min.

[0213] The preferences given above for the curable polymer P, the at least one polymeric blowing agent BA, the at least one thermoplastic polymer TP, the at least one solid rubber R, the at least one epoxy-functional polymer EP, the at least one acid anhydride-functional polymer AP, the at least one free radical initiator I, the at least one co-agent CA apply equally for all subjects of the present invention unless stated otherwise.

[0214] Another subject of the present invention is a baffle and / or a reinforcement element for hollow structures comprising or essentially consisting of the thermally expandable composition of the present invention.

[0215] Such elements are used to seal, baffle, and / or reinforce hollow structures, for example, a cavity in a hollow structural part of an automobile. Hollow parts in cars may include body components (for example panels), frame components (for example, hydroformed tubes), pillar structures (for example, A, B, C, or D-pillars), bumpers, roofs, or the like.

[0216] In embodiments, the baffle and / or reinforcement element for hollow structures essentially consists of the thermally expandable composition of the present invention. In these embodiments, it is advantageous to provide the element with such a shape that it can be easily fitted into and attached to the walls of the hollow structure to be baffled and / or reinforced. Such shaped elements can be provided from the thermally expandable composition, for example, by injection molding, punching or stamping, or extrusion through a shape template. In further embodiments, the baffle and / or reinforcement element further comprises a carrier on which the thermally expansible composition is deposited or attached. Such a design may be more cost-efficient and it may facilitate fixation of the baffle and / or reinforcement element on the walls of the structure to be baffled and / or reinforced, for example by incorporation of pins, bolts, or hooks on the carrier element. Furthermore, with a suitable design of the carrier element, the mechanical performance and stability of the baffle and / or reinforcement element can be improved.

[0217] The carrier of the baffle and / or reinforcement element, if used, may consist of any material that can be processed into a shape. Preferred materials for the carrier include polymeric materials, such as a plastic, elastomers, thermoplastics, blends thereof, and the like. Preferred thermoplastic materials include, without limitation, polymers such as polyurethanes, polyamides, polyesters, polyolefins, polysulfones, polyethylene terephthalates (PET), polyvinylchlorides (PVC), chlorinated polyolefins, and the like. Especially preferred are high-temperature stable polymers such as poly(phenyl ethers), polysulfones, polyethersulfones, polyamides, in particular polyamide 6, polyamide 6,6, polyamide 11 , polyamide 12, and mixtures thereof. Other suitable materials for the carrier include metals, especially aluminum or steel, or naturally grown, organic materials, such as wood or other (pressed) fibrous materials. Also glassy or ceramic materials can be used. It is also possible to use any combination of such materials. It is also contemplated that such materials can be filled, for example, with fibers, minerals, clays, silicates, carbonates, combinations thereof, or the like, or be foamed.

[0218] The carrier element can further exhibit any shape or geometry. It can also consist of several, not directly connected parts. For example, it can be massive, hollow, or foamed, or it can exhibit a grid-like structure. The surface of the carrier element can typically be smooth, rough, or structured, according to the intended use of the baffle and / or reinforcement element.

[0219] Another subject of the present invention is a process for manufacturing a baffle and / or reinforcement element of the present invention, wherein the thermally expandable composition is injection-molded onto a carrier or co-extruded with a carrier. The details of the manufacturing process of a baffle and / or reinforcement element of the present invention depends largely on the material of the carrier. If the material of the carrier can be (injection-) molded or extruded, the baffle and / or reinforcement element can be produced in a two-step injection-molding process or by co-extruding the carrier and the thermally expandable composition.

[0220] In case of a two-step injection molding process, the first step comprises injecting the material of the carrier into a mold. After solidification, the cavity of the injection molding tool is enlarged or adjusted or the injection-molded piece is transferred into another tool followed by a second step comprising injecting of the thermally expandable composition.

[0221] In case the carrier cannot be shaped by injection-molding or extrusion, for example, because it is composed of a metal or an alloy, the carrier may be first manufactured by a suitable process and then introduced into an injection-molding tool. The thermally expandable composition may then be injection-molded into the tool where the carrier was previously placed. Another possibility is to extrude the thermally expandable composition onto a pre-fabricated carrier element. Of course there is also the possibility of manufacturing the carrier and an element of the thermally expandable composition individually by any suitable process, and then attaching the element of the thermally expandable composition to the carrier by any suitable means, such as chemically or physically, for example by gluing or the like, or mechanically, for example, by bolting, screwing, or the like.

[0222] Another subject of the present invention is the use of the baffle and / or reinforcement element of the present invention for sealing, baffling, or reinforcing of a cavity or a hollow structure of a land-, water-, or air-vehicle, preferably an automotive vehicle, and / or a cavity of a building such that the transmission of noise, vibrations, humidity, and / or heat is reduced, and / or the structure surrounding said cavity or hollow structure is mechanically strengthened.

[0223] Still another subject of the present invention is a method for sealing, baffling and / or reinforcing a cavity or a hollow structure, wherein an element comprising a thermally expandable composition according to the present invention is introduced into said cavity or hollow structure and subsequently expanded by heat and / or by UV-treatment such that said cavity or hollow structure is at least partially filled by the expanded composition.

[0224] The temperature of the thermal expansion step is preferably 140 - 250 °C, more preferably of 150 - 220 °C, even more preferably 150 - 200 °C. Preferred duration of the thermal expansion step, i.e. preferred baking time of the thermally expandable composition, is 5 - 90 min, more preferably 10 - 60 min, even more preferably 10 - 30 min.

[0225] Regarding the thermal activation of the element comprising the thermally expandable composition when used in manufacturing of automotive vehicles, it is advantageous to couple the thermal activation with another process step involving heat treatment. An example of such a process step is the electrocoating (cathodic dip painting / coating) of the chassis of a car body.

[0226] Examples

[0227] The followings chemicals shown in Table 1 were used in formulating the thermally expandable compositions.

[0228] Table 1 Preparation of polymeric blowing agents

[0229] Polystyrene-sulfonylhydrazide (PSSH)

[0230] PSSH was synthesized using the reaction scheme presented in Figure 1 .

[0231] In the first step, a solution of polystyrene (from Sigma Aldrich) having a molecular weight of about 35000 g / mol (25 grams, 0.24 mol, in 100 mL of chloroform) was added dropwise over 2 hours to stirred chlorosulfonic acid (280 grams, 2.4 mol) maintained at 4 °C. After continuously mixing for 3 hours at 0 - 4°C, followed by approximately 16 hours at room temperature, the thus obtained amber reaction mixture was added to cold deionized water resulting in precipitation of a white to cream colored solid. The precipitate was filtered and washed repeatedly with ice cold water. The agueous filtrate and washings were discarded and the filter-cake was washed with petroleum ether, diethyl ether and finally dried in vacuum at 60°C until a constant weight was obtained. The dried crude reaction product was precipitated from its solution in tetrahydrofuran (THF) by addition into diethyl ether. 34 grams (0.17 mol; 70% yield) of a white to cream solid material was obtained after drying in vacuum at 60 °C.

[0232] In the second step, 18 gram (0.088 mol) of the chlorosulfonated polystyrene obtained in the first step in 150 ml of tetrahydrofuran was cooled down to 0 to 4 °C and treated with 14 grams of agueous 50 % hydrazine, which was added dropwise over 1 h into the solution. After mixing approximately 2.5 hours at room temperature, the reaction mixture containing a finely precipitated solid was filtered. The filter-cake was washed consecutively with fresh tetrahydrofuran and diethyl ether and air dried. The combined filtrate and washings were discarded. The dried, pale-yellow solid was washed with cold water to remove any hydrazine hydrochloride. The agueous insoluble solid was then washed consecutively with methyl alcohol and ether to give 14.3 gram (0.072 mol; 82 % yield), after drying in vacuum at 60°C, of polystyrene-sulfonyl hydrazide (PSSH). Poly(Methacryloyl-4,4’-oxydibenzenesulfonohydrazide) (Poly(MAOBSH))

[0233] Poly(MAOBSH) was synthesized using the reaction scheme presented in Figure 2.

[0234] In the first step, 25 gram (0.07 mol) of OBSH was added to a 500 ml round bottomed flask containing 140 ml THF. 0.5 ml (0.0035 mol) of triethylamine (TEA) and a trace amount (0.02 gram) of hydroquinone were added and the solution was stirred for 15 minutes. Then 8 ml (0.075 mol) of methacryloyl chloride (MAC) was added dropwise via a dropping funnel to avoid exceeding a reaction temperature of 40 °C (max. temperature of 38 °C). After the addition of MAC, the solution was transferred to a separating funnel and 5.8 gram (0.07 mol) of NaCOs in approximately 20 ml water was added. This released CO2 and the solution became transparent with a phase separation occurring. The organic layer was collected, dried with anhydrous MgSO4, and concentrated on a rotary evaporator to obtain MAOBSH as a white crystalline solid. The product was placed in a vacuum oven for 24 hours at 60 °C to dry. This reaction was repeated a further 4 times to upscale the yield of MAOBSH. The yield for each of the 5 reactions and the total yield are shown below in Table 2.

[0235] Table 2

[0236] In the second step, 25 gram (0.059 mol) of MAOBSH in 250 ml THF was added to the three necked round bottomed fitted with a condenser. The flask was purged with nitrogen gas, sealed and heated to 70 °C with stirring under constant nitrogen flow. To the stirred solution, 0.75 gram azobis(isobutyronitril) Al BN was added. The solution was stirred at 70 °C for 24 hours under continuous flow of N2. After 24 hours, the solution was transferred to a beaker containing approximately 300 ml diethyl ether and poly(MAOBSH) was precipitated. The white solid was collected by filtration, washed twice with diethyl ether and dried in a vacuum oven at 60 °C. This reaction was repeated three times using all MAOBSH produced in step 1. The final reaction used 12 gram MAOBSH, 120 ml THF and 0.375 gram AIBN under the same reaction conditions. The yield for each of the 4 reactions and the total yield are shown in the Table 3 below.

[0237] Table 3

[0238] Oligomeric siloxane Boc-carbamates

[0239] Three different Boc-carbamates derivatives; Boc-TESP-carbamate (BC), Boc-AE- TESP-dicarbamate (BDC) and Boc-AEAE-TMSP-tricarbamate (BTC) were first synthesized according to the reaction scheme shown in Figure 3 using following general procedure.

[0240] Amino-functional silane was added to a 250 mL three-necked round-bottomed flask, along with 60 mL of THF and cooled in an ice / water bath. Triethylamine (TEA) was then added, followed by the addition of a solution of di-tert-butyl dicarbonate (Boc2O) in THF via a dropping funnel. The mixture was left to stir in the ice / water bath at room temperature. The reaction was considered to be complete when the IR spectrum of the solution showed no peak corresponding to Boc2O. The solvent was removed on a rotary evaporator and the resulting liquid product was dried on the high vacuum for 2 days. The product was weighed and analyzed via ATR-IR,1H NMR,13C NMR, gas chromatography (GC) to confirm the identity of the compound. Quantities of reagents and the product yields are shown below in the Table 4. Table 4

[0241] The prepared Boc-TESP-carbamate (BC) was used as a blowing agent in reference Example 4.

[0242] In the second step, an oligomeric siloxane Boc-carbamate was synthetized from the tert-butyl (3-(triethoxysilyl)propyl)-carbamate (BC) according to the reaction scheme shown in Figure 4 using following procedure. 10 gram (31.1 mmol) of the tert-butyl (3-(triethoxysilyl)propyl)-carbamate (BC) was added into a 100 ml 3-neck round flask equipped with a reflux condenser and a magnetic stirrer. 0.378 ml (21 mmol) deionized H2O was added, followed by the addition of 2 ml ethanol (EtOH). The7 solution was stirred for 15 minutes at room temperature. 0.07 gram (0.21 mmol) NaOEt solution was added to the reaction mixture and stirred at 80 °C under nitrogen atmosphere. Reaction control by NMR once in 1 hour until no change in spectra. Subsequently, the reaction mixture was filtrated and concentrated by removing the ethanol (ETOH) using a rotary evaporator. 20 grams (24.5 mmol; 79 % yield) of a brownish, viscous liquid was obtained. Properties of the synthetized blowing agents are summarized in Table 5.

[0243] Table 5

[0244] Decomposition peak temperature

[0245] Decomposition peak temperatures of the blowing agents were determined by DSC822e differential scanning calorimeter from Mettler-Toledo by keeping the sample for 2 min at 25°C, then heating the sample from 25°C to 280 °C at a rate of 5 °C / min, then keeping the sample for 2 min at 280°C and finally cooling the sample from 280°C to 25 °C at a rate of 10°C / min.

[0246] Preparation of thermally expandable compositions

[0247] All inventive and non-inventive thermally expandable compositions were produced using standard production equipment suitable to compound thermoplastics with temperature control, i.e. twin screw extruder, Buss kneader or a Banbury mixer.

[0248] Constituents of the polymer matrix (TP, EP, AP) and the filler were mixed until homogeneous at a temperature 100 - 110 °C after which the system was cooled below activation of heat reactive raw materials (< 90 °C). Heat reactive raw materials (BA, catalyst) were then mixed into the system until homogeneous. The obtained compositions were subsequently hot-pressed into test samples that were used in the volume expansion testing procedures. The ingredients of the tested thermally expandable compositions and their measured properties are shown in Table 6.

[0249] Volume expansion

[0250] Expansion properties were tested for all samples by heat treating (baking) the individual samples at temperatures of 155 and 195 °C for 15 and 20 minutes in an oven, respectively. The heating time from room temperature (23 °C) to the respective baking temperature was 2 min (to 155 °C) or 3 min (to 195 °C). The volume expansions (in % based on the original volume prior to expansion) at the corresponding baking temperatures are shown in Table 6.

[0251] Volume expansions were determined for each sample by measuring the density before and after expansion. The densities were determined according to DIN EN ISO 1183 using the water immersion method (Archimedes principle) in deionized water and a precision balance to measure the mass.

[0252] FIG. 5 illustrates thermogravimetric analysis curves showing mass changes versus temperature, according to aspects of the present disclosure.

[0253] FIG. 5 illustrates thermogravimetric analysis (TGA) curves showing mass changes versus temperature for two different blowing agents. A first thermogravimetric curve 1 corresponds to a polymeric sulfonyl hydrazide blowing agent (PSSH) prepared by chlorosulfonation of polystyrene followed by reaction with hydrazine. The polymeric sulfonyl hydrazide blowing agent has a molecular weight of about 35,000 g / mol. A second thermogravimetric curve 4 corresponds to a non-polymeric sulfonyl hydrazide blowing agent (TSH) used as a reference.

[0254] The first thermogravimetric curve 1 shows a mass change of 37.9% at 150°C, 38.8% at 200°C, 39.4% at 250°C, and 42.3% at 300°C. The polymeric sulfonyl hydrazide blowing agent exhibits instantaneous mass loss at about 149°C followed by a plateau until about 250°C in the TGA curve.

[0255] In contrast, the second thermogravimetric curve 4 shows a mass change of 8.9% at 150°C, 50.4% at 200°C, 72.6% at 250°C, and 80.9% at 300°C. The non-polymeric sulfonyl hydrazide blowing agent exhibits a more gradual and continuous mass loss across the temperature range. The thermogravimetric analysis curves demonstrate the controlled volatile organic compound (VOC) generation of the polymeric blowing agent. The first thermogravimetric curve 1 shows that substantially all VOC release for the polymeric sulfonyl hydrazide blowing agent occurs during the initial decomposition phase, corresponding to the expansion process. Minimal additional VOC release is observed at higher temperatures, as indicated by the plateau region of the curve.

[0256] In differential scanning calorimetry (DSC) analysis, the polymeric sulfonyl hydrazide blowing agent exhibits an exothermic peak at a temperature 7 degrees lower than the non-polymeric sulfonyl hydrazide blowing agent.

[0257] The thermogravimetric analysis (TGA) data illustrated in FIG. 5 demonstrates the controlled volatile organic compound (VOC) generation characteristics of the polymeric blowing agent. The first thermogravimetric curve 1 corresponds to a polymeric sulfonyl hydrazide blowing agent (PSSH) prepared by chlorosulfonation of polystyrene followed by reaction with hydrazine. The second thermogravimetric curve 4 corresponds to a non-polymeric sulfonyl hydrazide blowing agent (TSH) used as a reference.

[0258] The first thermogravimetric curve 1 shows that substantially all VOC release for the polymeric sulfonyl hydrazide blowing agent occurs during the initial decomposition phase, corresponding to the expansion process. The first thermogravimetric curve 1 exhibits a rapid mass loss of 37.9% at 150°C, followed by minimal additional mass loss up to 300°C. In contrast, the second thermogravimetric curve 4 shows a more gradual and continuous mass loss across the temperature range, with 8.9% mass loss at 150°C increasing to 80.9% at 300°C.

[0259] The reduced volatile organic content of the polymeric blowing agent compared to the non-polymeric reference is evidenced by the lower total mass loss observed in the first thermogravimetric curve 1. The polymeric blowing agent exhibits a plateau region in the TGA curve from approximately 150°C to 250°C, indicating minimal additional VOC release at higher temperatures.

[0260] A polymeric blowing agent may be mixed into baffle formulations using a Brabender mixer. Processing a baffle formulation containing a polymeric blowing agent on calender rolls at 95°C for 5 minutes may improve dispersion of the polymeric blowing agent. Baffle formulations containing a polymeric blowing agent may exhibit expansion values up to 493% at 150°C.

[0261] The thermally expandable composition of the present invention comprises at least one polymeric blowing agent BA selected from sulfonyl hydrazide-functionalized polymers, sulfonyl semicarbazide-functionalized polymers, carbamate-functionalized polymers, and ureido carbamate-functionalized polymers. These polymeric blowing agents exhibit controlled volatile organic compound (VOC) generation compared to conventional non-polymeric blowing agents.

[0262] FIG. 5 illustrates thermogravimetric analysis (TGA) curves showing mass changes versus temperature for two different blowing agents. The first thermogravimetric curve 1 corresponds to a polymeric sulfonyl hydrazide blowing agent (PSSH) prepared by chlorosulfonation of polystyrene followed by reaction with hydrazine. The second thermogravimetric curve 4 corresponds to a non-polymeric sulfonyl hydrazide blowing agent (TSH) used as a reference.

[0263] The first thermogravimetric curve 1 shows that substantially all VOC release for the polymeric sulfonyl hydrazide blowing agent occurs during the initial decomposition phase, corresponding to the expansion process. The first thermogravimetric curve 1 exhibits a rapid mass loss of 37.9% at 150°C, followed by minimal additional mass loss up to 300°C. In contrast, the second thermogravimetric curve 4 shows a more gradual and continuous mass loss across the temperature range, with 8.9% mass loss at 150°C increasing to 80.9% at 300°C.

[0264] The reduced volatile organic content of the polymeric blowing agent compared to the non-polymeric reference is evidenced by the lower total mass loss observed in the first thermogravimetric curve 1. The polymeric blowing agent exhibits a plateau region in the TGA curve from approximately 150°C to 250°C, indicating minimal additional VOC release at higher temperatures.

[0265] The controlled VOC generation profile of the polymeric blowing agents provides environmental and safety benefits compared to conventional non-polymeric blowing agents. The reduced VOC emissions during and after the expansion process may result in improved air quality in manufacturing environments and reduced environmental impact.

[0266] In exemplary embodiments, the polymeric blowing agent BA may be a sulfonyl hydrazide-functionalized polymer of formula (I): wherein Ri is a polymeric backbone, and i has a value of 3 or more. The polymeric backbone Ri may be a styrene block copolymer or a poly(meth)acryloyl.

[0267] In some examples, the styrene block copolymer may be of type S-X-S, S-X-P, or M- X-S, where S designates a styrene block, M designates a methacrylate block, P designates a propylene block, and X designates an elastic a-olefin block. The elastic a-olefin block X may be selected from butylene, ethylene / butylene, ethylene / propylene, ethylene-(ethylene-propylene), isoprene, and isoprene / butadiene.

[0268] Alternatively, the polymeric blowing agent BA may be a carbamate-functionalized polymer of formula (V): wherein Rs is a polymeric backbone, and q is 1 , 2, 3, or 4. The polymeric backbone Rs may be a polysiloxane or a polyurethane.

[0269] In further embodiments, the polymeric blowing agent BA may be a sulfonyl semicarbazide-functionalized polymer of formula (III) or (IV), wherein the polymeric backbone R3 is a polysiloxane or a polyurethane.

[0270] Additionally, the polymeric blowing agent BA may be an ureido carbamate- functionalized polymer of formula (VII), wherein the polymeric backbone Rg is a polysiloxane or a polyurethane.

[0271] Specific examples of suitable polymeric blowing agents BA include polystyrenesulfonylhydrazide, poly(Methacryloyl-4,4'-xydibenzenesulfonohydrazide), and tris(tert- butyl(3-dietheoxysilyl)propyl)-tricarbamate.

[0272] The thermally expandable composition with controlled volatile organic compound (VOC) generation may be used in various applications across different industries. In automotive manufacturing, the thermally expandable composition may be utilized to produce baffle and reinforcement elements for sealing, baffling, or reinforcing cavities or hollow structures in vehicles. A baffle or reinforcement element may be manufactured by injection-molding the thermally expandable composition onto a carrier or by co-extruding the thermally expandable composition with a carrier.

[0273] The baffle or reinforcement element may be introduced into a cavity or hollow structure of an automotive vehicle. Upon application of heat, the thermally expandable composition expands to at least partially fill the cavity or hollow structure. This expansion process may reduce transmission of noise, vibrations, humidity, and heat within the vehicle. Additionally, the expanded composition may mechanically strengthen the structure surrounding the cavity.

[0274] In building construction, the thermally expandable composition may be employed for sealing, baffling, or reinforcing cavities in buildings. The controlled VOC generation during expansion may provide improved air quality and reduced environmental impact compared to conventional expandable compositions. The baffle or reinforcement element may be introduced into a building cavity and expanded by heat to at least partially fill the cavity, enhancing insulation properties and structural integrity.

[0275] The thermally expandable composition may also find applications in other land-, water- , or air-vehicles. For example, in marine vessels, the composition may be used to reinforce hull structures or seal compartments. In aircraft, the composition may be utilized to reduce noise transmission between cabin sections or reinforce structural elements.

[0276] A method for sealing, baffling and reinforcing a cavity or hollow structure may involve introducing an element comprising the thermally expandable composition into the cavity or hollow structure. The composition may then be expanded by heat to at least partially fill the cavity or hollow structure. This method may be applied in various industries to improve structural properties, reduce noise and vibration transmission, and enhance insulation.

[0277] The controlled VOC generation of the thermally expandable composition may provide environmental and safety benefits across these applications. Reduced VOC emissions during and after the expansion process may result in improved air quality in manufacturing environments and reduced environmental impact in end-use applications.

[0278] Table 7:

[0279] : 150°C: Characteristic Decomposition Temperature of the Blowing Agents Table 7 presents a comparison of mass changes measured by thermogravimetric analysis (TGA) for two different blowing agents at various temperatures as shown in Fig.5. The table compares the behavior of a reference non-polymeric blowing agent (TSH) with a polymeric sulfonyl hydrazide blowing agent (PSSH).

[0280] The data shows mass changes at four temperature points: 150°C, 200°C, 250°C, and 300°C. At 150°C, which is noted as the characteristic decomposition temperature of the blowing agents, TSH exhibits a mass change of 8.9%, while PSSH shows a significantly higher mass change of 37.9%.

[0281] As the temperature increases, TSH demonstrates a gradual increase in mass change, reaching 50.4% at 200°C, 72.6% at 250°C, and 80.9% at 300°C. In contrast, PSSH shows a more stable profile after the initial decomposition, with mass changes of 38.8% at 200°C, 39.4% at 250°C, and 42.3% at 300°C. This data may illustrate the differences in thermal decomposition behavior between the non-polymeric and polymeric blowing agents, potentially highlighting the controlled volatile organic compound (VOC) generation characteristics of the polymeric blowing agent PSSH compared to the reference TSH.

[0282] Table 6

[0283]

Claims

Claims1 . A thermally expandable composition comprising: a. At least one thermoplastic polymer TP and / or at least one solid rubber R and b. At least one polymeric blowing agent BA selected from the group consisting of sulfonyl hydrazide-functionalized polymers, sulfonyl semicarbazide-functionalized polymers, carbamate-functionalized polymers, and ureido carbamate-functionalized polymer wherein the polymeric blowing agent BA has a number average molecular weight (Mn) determined by gel permeation-chromatography (GPC) using polystyrene as standard of at least 500 g / mol, preferably at least 750 g / mol, wherein the thermally expandable composition exhibits controlled volatile organic compound (VOC) generation with substantially all VOC release occurring during expansion, and / or wherein the composition releases VOCs during expansion with no significant VOC release after expansion.

2. The thermally expandable composition according to claim 1 , wherein the polymer of the polymeric blowing agent BA is selected from polystyrene, styrene block copolymer, poly(meth)acrylate, polyurethane, and polysiloxane.

3. The thermally expandable composition according to claim 2, wherein the styrene block copolymer is of type S-X-S, S-X-P, or M-X-S, wherein the S designates a styrene block, M a methacrylate block, P a propylene block, and X an elastic a-olefin block, preferably selected from the group consisting of butylene, ethylene / butylene, ethylene / propylene, ethylene- (ethylene-propylene), isoprene, and isoprene / butadiene.

4. The thermally expandable composition according to any one of previous claims, wherein the sulfonyl hydrazide-functionalized polymer is a compound of formula (I)wherein Ri is a polymeric backbone, h has a value of 0 or 1 , i has a value of 3 or more, and wherein R2 represents a moiety of formula (II)5. The thermally expandable composition according to claim 4, wherein the polymeric backbone R1 is a styrene block copolymer or a poly(meth)acryloyl.

6. The thermally expandable composition according to any of previous claims, wherein the sulfonyl hydrazide-functionalized polymer is selected from:wherein j is 1 or 2, k is 1 or 2, n is 0, 1 , or 2, m is 1 or 2, and o is 2 or more.

7. The thermally expandable composition according to any one of previous claims, wherein the sulfonyl semicarbazide-functionalized polymer is a compound of formula (III)wherein R3 is a polymeric backbone,R4 is a hydrogen atom, a linear or branched alkyl group, a cycloaliphatic group or an aryl or an alkyl aryl group, and p has a value of 1 , 2, or 3.

8. The thermally expandable composition according to claim 7, wherein the polymeric backbone R3 is a polysiloxane or a polyurethane.

9. The thermally expandable composition according to any one of previous claims, wherein the carbamate-functionalized polymer is a compound of formula (V)wherein Rs is a polymeric backbone,Re is a linear or branched C2 to C4 alkyl group, R? is a hydrogen atom, a substituted dicarbamate or a tertiary carbamate,Rs is a tertiary alkyl group, particularly a tertiary butyl group, and q is 1 , 2, 3, or 4.

10. The thermally expandable composition according to claim 9, wherein the polymeric backbone Rs is a polysiloxane or a polyurethane.

11. The thermally expandable composition according to any one of previous claims, wherein the ureido carbamate-functionalized polymer is a compound of formula (VII)wherein Re is a linear or branched C2 to C4 alkyl group,R9 is a polymeric backbone,R10 is a linear or branched alkyl group, a cycloaliphatic group or an aryl or an alkyl aryl group,R11 is a hydrogen atom, a substituted dicarbamate or tertiary carbamate,R12 is a tertiary alkyl group, particularly a tertiary butyl group, and r is 1 , 2, or 3.

12. The thermally expandable composition according to claim 11 , wherein the polymeric backbone R9 is a polysiloxane or a polyurethane.

13. The thermally expandable composition according to any one of claims 4- 12, wherein the polymeric blowing agent BA is selected from sulfonyl hydrazide-functionalized polymer of formula (I) and carbamate- functionalized polymer of formula (V), wherein the polymeric backbone Rs is preferably a polysiloxane.

14. The thermally expandable composition according to any one of previous claims, wherein the polymeric blowing agent BA is selected from polystyrene-sulfonylhydrazide, poly(Methacryloyl-4,4’- xydibenzenesulfonohydrazide), and tris(tert-butyl(3-dietheoxysilyl)propyl)- tricarbamate.

15. The thermally expandable composition according to any one of previous claims, wherein the at least one thermoplastic polymer TP is selected from the group consisting of ethylene-vinyl acetate copolymers, olefin (meth)acrylate copolymers, olefin alkyl (meth)acrylate copolymers, olefin (meth)acrylic acid copolymers, olefin glycidyl (meth)acrylate copolymers, olefin alkyl acrylate glycidyl (meth)acrylate terpolymers, and glycidyl (meth)acrylate grafted (co)polymers.

16. Baffle and / or a reinforcement element for hollow structures comprising a thermally expandable composition according to any one of claims 1-15.

17. Baffle and / or reinforcement element of claim 16 further comprising a carrier on which the thermally expandable composition is deposited or attached.

18. A process for manufacturing a baffle and / or reinforcement element according to claim 17, wherein the thermally expandable composition is injection-molded onto the carrier or co-extruded with the carrier.

19. Use of the baffle and / or reinforcement element according to claim 16 or 17 for sealing, baffling, or reinforcing of a cavity or a hollow structure of a land-, water-, or air-vehicle, preferably an automotive vehicle, and / or a cavity of a building such that the transmission of noise, vibrations, humidity, and / or heat is reduced, and / or the structure surrounding said cavity is mechanically strengthened.

20. Method for sealing, baffling and / or reinforcing a cavity or hollow structure, wherein an element comprising a thermally expandable composition according to any of claims 1-15 is introduced into said cavity or hollow structure and subsequently expanded by heat such that said cavity or hollow structure is at least partially filled by the expanded composition.

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