Pressure sensitive adhesive compositions with improved thermal stability and uses thereof

Abstract

The present invention relates to a radiation curable adhesive composition comprising: a) at least one styrene-based polymer, b) at least one tackifying resin, c) at least one photoinitiator, and d) at least one cross-linking agent wherein the at least one photoinitiator can be activated with radiation having a wavelength of 365-500 nm in order to initiate a curing reaction of the adhesive composition.

Description

Technical Field

[0001] The present invention relates to pressure-sensitive adhesive compositions, particularly hot-melt pressure-sensitive adhesive compositions, and their use for providing self-adhering vibration and noise damping elements. Background Art

[0002] Damping materials are widely used in automobiles, household appliances, and general industry to reduce unwanted vibrations, structure-borne sound, and air-borne sound. For example, in motor vehicles, it is desirable to prevent vibrations generated by motors, pumps, gears, and other power generators from being transmitted through the vehicle body into the passenger compartment. Structure-borne sound is generated when vibrations from a power generator are transmitted through a support structure (usually a frame or other hollow structure) to a noise-emitting surface (such as a metal or plastic panel) that converts mechanical vibrations into sound waves. By directly applying a damping material to the structures and surfaces of components that are disturbed by vibrations, such as to the surfaces of vehicle panels, floors, and to the housings of articles in household appliances and general industry (such as machines, washing machines, and dryers), structure-borne sound and vibrations can generally be effectively reduced.

[0003] Damping materials for vibration surface damping are typically provided as prefabricated single-layer and multi-layer damping elements or as liquid compositions that are directly applied to the surface of a substrate. Prefabricated damping elements typically include a layer of damping material that is in direct contact with the surface of the substrate to be damped against vibration interference. The damping material layer is capable of dissipating the kinetic energy of the vibrating surface into heat energy via the extension and compression of the damping layer material. Commonly used damping materials include highly filled compositions that contain asphalt, elastomers, or thermoplastic polymers and varying amounts of additives such as plasticizers, processing aids, rheological modifiers, and drying agents. Fillers are added to these compositions to meet different design objectives. Some fillers are used to improve acoustic damping performance, while other fillers are used to reduce the density of the material or replace more expensive materials to reduce the cost of raw materials. Liquid-applied damping systems are typically heat-drying, gelling, or reactive compositions that are applied in liquid form, for example by spraying, onto the surface of a substrate.

[0004] The damping element may also include an adhesive layer, such as a hot melt or pressure-sensitive adhesive layer, to enable the damping element to bond to a surface. Hot melt adhesives are one-component, water-free and solvent-free adhesives that are solid at room temperature. They are applied as a melt and establish an adhesive bond by curing upon cooling. Pressure-sensitive adhesives (PSAs) are viscoelastic materials that adhere immediately to almost any type of substrate upon the application of slight pressure and are permanently tacky. Pressure-sensitive adhesives applied as a melt are called hot melt pressure-sensitive adhesives (HM-PSAs). Due to the permanent tackiness of the adhesive material, the pressure-sensitive adhesive layer is typically covered with a release liner to avoid unwanted bonding and protect the adhesive layer from contamination.

[0005] Due to the non-crosslinked structure of the cured adhesive, non-reactive HM-PSA compositions have the disadvantage of exhibiting poor thermal stability. This is a significant disadvantage in some automotive applications where the bonded structure undergoes several oven processes at high temperatures. Chemically crosslinked HM-PSA compositions have high thermal stability, but they tend to have poor adhesion to oiled substrates, especially oiled metal substrates.

[0006] Therefore, there is a need for an HM-PSA composition having improved thermal stability and good adhesion to oiled substrates. Such an adhesive composition is particularly suitable for providing vibration and noise damping elements, especially for motor vehicles. Summary of the Invention Overview of the Invention

[0008] The object of the present invention is to provide a pressure-sensitive adhesive composition having improved thermal stability and good adhesion to oiled substrates, especially oiled metal substrates.

[0009] It has surprisingly been found that the features of claim 1 achieve this object.

[0010] The subject matter of the present invention relates to a radiation-curable adhesive composition comprising:

[0011] a) at least one styrene-based polymer SC,

[0012] b) at least one tackifying resin TR,

[0013] c) at least one photoinitiator PI, and

[0014] d) at least one crosslinking agent CA,

[0015] wherein the at least one photoinitiator PI can be activated with radiation having a wavelength of 365 - 500 nm to initiate the curing reaction of the adhesive composition.

[0016] Other aspects of the present invention are presented in additional independent claims. Preferred embodiments are outlined throughout the specification and the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A cross-section of a vibration and noise damping element (1) is shown, which includes a damping layer (2) having a first surface (3) and a second surface (3'), and an adhesive layer (4) covering the first surface (3) of the damping layer (2).

[0018] Figure 2 A cross-section of a vibration damping system is shown, which includes a substrate (6) having a noise-emitting surface (7) and a vibration and noise damping element (1) including a damping layer (2) and an adhesive layer (4), wherein the first surface (3) of the damping layer (2) is adhesively bonded to the noise-emitting surface (7) via the adhesive layer (4). DETAILED DESCRIPTION OF THE INVENTION

[0020] A first subject of the present invention is a radiation-curable adhesive composition comprising:

[0021] a) at least one styrene-based polymer SP,

[0022] b) at least one tackifying resin TR,

[0023] c) at least one photoinitiator PI, and

[0024] d) at least one crosslinking agent CA,

[0025] wherein the at least one photoinitiator PI can be activated by radiation having a wavelength of 365 - 500 nm to initiate the curing reaction of the radiation-curable adhesive composition.

[0026] The term "polymer" refers to a collection of chemically homogeneous macromolecules produced by a polymerization reaction (polymerization, addition polymerization, condensation polymerization), wherein the macromolecules differ in their degree of polymerization, molecular weight, and chain length. The term also includes derivatives of the collection of macromolecules produced by the polymerization reaction, i.e., compounds obtained by the reaction of functional groups in a predetermined macromolecule (e.g., addition or substitution), and which may be chemically homogeneous or chemically inhomogeneous.

[0027] The term "molecular weight" refers to the molar mass (g / mol) of a molecule or a part of a molecule (also referred to as a "structural part"). The term "average molecular weight" refers to the number-average molecular weight (Mn) or weight-average molecular weight (Mw) of an oligomer or polymer mixture of molecules or structural parts. The molecular weight can be determined by conventional methods, preferably by gel permeation chromatography (GPC), using polystyrene as a standard sample, using styrene-divinylbenzene gels with porosities of 100 Å, 1000 Å, and 10000 Å as columns, and depending on the molecule, using tetrahydrofuran as a solvent (at 35 °C) or 1,2,4-trichlorobenzene as a solvent (at 160 °C) for the determination.

[0028] The term "softening point" or "softening temperature" refers to the temperature at which a compound softens in a rubbery state or the temperature at which the crystalline part within the compound melts. The softening point can be measured by the ring and ball method according to the DIN EN 1238:2011 standard.

[0029] The "amount or content of at least one component X" in a composition, such as the "amount of at least one styrene-based polymer", refers to the sum of the individual amounts of all styrene-based polymers contained in the composition. For example, in the case where a composition contains 20% by weight of at least one styrene-based polymer, the sum of the amounts of all styrene-based polymers contained in the composition is equal to 20% by weight.

[0030] The term "photoinitiator" refers to a compound that generates reactive species (such as free radicals, cations, or anions) when exposed to UV or visible light radiation, and the reactive species initiate chemical reactions such as polymerization and / or curing reactions.

[0031] According to one or more embodiments, at least one photoinitiator PI can be activated with radiation having a wavelength in the range of 365 - 475 nm, preferably 365 - 450 nm, more preferably 365 - 415 nm, to initiate the curing reaction of a radiation-curable adhesive composition. According to one or more additional embodiments, at least one photoinitiator PI can be activated with radiation having a wavelength in the range of 375 - 485 nm, preferably 380 - 475 nm, more preferably 385 - 465 nm, even more preferably 390 - 450 nm, to initiate the curing reaction of a radiation-curable adhesive composition. The term "curing" herein refers to a chemical reaction including the formation of bonds that result in, for example, chain extension and / or crosslinking of polymer chains.

[0032] A radiation-curable adhesive composition containing a photoinitiator that can be activated with radiation having a wavelength falling within the above ranges can be cured by using visible light instead of only using UV radiation, which enables a simplified and safer method for applying the adhesive composition.

[0033] Suitable compounds for use as at least one photoinitiator PI include, for example, 2,4,6-trimethylbenzoyl diphenylphosphine oxide (TPO), 2,4,6-trimethylbenzoyl ethoxyphenylphosphine oxide (TPO-L), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (BAPO), bis(cyclopentadienyl)bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-1H-pyrrole titanium complex, polybutylene glycol bis(9-oxo-9H-thioxanthenyloxy)acetate (TX), 2-isopropylthioxanthone (ITX), 1-chloro-4-propoxythioxanthone (CPTX), camphorquinone (CQ), bis-(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide and 2-benzyl-2-(dimethylamino)-4-morpholinobutyrophenone (DBMP).

[0034] Suitable photoinitiators may be commercially available, for example, under the trade names 819, TPO, TP, ITX, DETX, 3644, EMK, 2100, BL 750, TX and BL 728 (all from IGM Resins).

[0035] The radiation-curable adhesive composition further comprises at least one crosslinking agent CA in addition to the photoinitiator PI.

[0036] According to one or more preferred embodiments, at least one crosslinking agent CA has at least two thiol groups, preferably at least three thiol groups, more preferably at least four thiol groups. The term "thiol group" herein refers to a mercapto group having the general formula -SH.

[0037] According to one or more embodiments, at least one crosslinking agent CA has a number average molecular weight (Mn) of 150 - 1500 g / mol, preferably 350 - 1000 g / mol, more preferably 450 - 850 g / mol as determined by gel permeation chromatography using polystyrene as a standard sample.

[0038] According to one or more embodiments, at least one crosslinking agent CA has at least three thiol groups, preferably at least four thiol groups and / or a number average molecular weight (Mn) of not more than 1000 g / mol, preferably 350 - 1000 g / mol, more preferably 450 - 850 g / mol, as determined by gel permeation chromatography using polystyrene as a standard sample. It has been found that such a crosslinking agent CA can provide a radiation-curable adhesive composition that exhibits a particularly short curing time, which may be advantageous in some applications.

[0039] Preferably, the amount of at least one styrene-based polymer SP accounts for not more than 50% by weight, preferably not more than 45% by weight, more preferably not more than 40% by weight of the total weight of the radiation-curable adhesive composition.

[0040] According to one or more embodiments, based on the total weight of the adhesive composition, the radiation-curable adhesive composition comprises 10 - 50% by weight, preferably 15 - 40% by weight, more preferably 20 - 35% by weight of at least one styrene-based polymer SP.

[0041] According to one or more embodiments, the radiation-curable adhesive composition comprises:

[0042] a) 10 - 50% by weight, preferably 15 - 40% by weight, more preferably 20 - 35% by weight of at least one styrene-based polymer SP,

[0043] b) 15 - 65% by weight, preferably 25 - 60% by weight, more preferably 30 - 55% by weight of at least one tackifying resin TR,

[0044] c) 0.25 - 5% by weight, preferably 0.5 - 3.5% by weight, more preferably 0.75 - 2.5% by weight of at least one photoinitiator PI, and

[0045] d) 0.05 - 5% by weight, preferably 0.25 - 3.5% by weight, more preferably 0.5 - 2.5% by weight of at least one crosslinking agent CA, all percentages being based on the total weight of the adhesive composition.

[0046] Suitable compounds for the styrene-based polymer SP include, for example, styrene block copolymers and styrene-butadiene rubber (SBR).

[0047] Suitable styrene block copolymers include SXS type block copolymers, where in each, S represents an inelastic styrene (or polystyrene) block and X represents an elastomeric α-olefin block, preferably having a glass transition temperature of -55°C to -35°C. The elastomeric α-olefin block can also be a chemically modified α-olefin block.

[0048] According to one or more embodiments, at least one styrene-based polymer SP is selected from styrene-isoprene-styrene (SIS) block copolymers, styrene-butadiene-styrene (SBS) block copolymers, styrene-isoprene-butadiene-styrene block copolymers (SIBS), and styrene-butadiene rubbers (SBR).

[0049] According to one or more embodiments, at least one styrene-based polymer SP comprises at least one styrene-isoprene-styrene (SIS) block copolymer SP1 and / or styrene-butadiene-styrene (SBS) block copolymer SP2, preferably having:

[0050] - a styrene content of not more than 60% by weight, preferably not more than 55% by weight, more preferably not more than 50% by weight, even more preferably not more than 45% by weight, and / or

[0051] - a melt flow rate measured according to ASTM D1238 (200 °C / 5 kg) of not more than 100 g / 10 min, more preferably not more than 75 g / 10 min, even more preferably not more than 50 g / 10 min, still more preferably not more than 30 g / 10 min.

[0052] Generally, the statement "at least one component X comprises at least one component XN", for example "at least one styrene-based polymer SP comprises at least one styrene-isoprene-styrene block copolymer SP1" should be understood in the context of the present disclosure as meaning that the adhesive composition comprises one or more styrene-isoprene-styrene block copolymers SP1 as representatives of at least one styrene block copolymer SP.

[0053] The term "styrene content of the block copolymer" refers to the weight percentage of styrene or polystyrene in the block copolymer and is based on the total weight of the block copolymer. The terms styrene content and polystyrene content can be used interchangeably. Preferred SIS and SBS block copolymers to be used as at least one styrene-based polymer SP have a linear, radial or star structure.

[0054] Suitable SIS block copolymers with a styrene content of not more than 45% by weight are commercially available, for example under the trade names For example D-1111P, D-1114P, D-1117P, D-1119P, D-1161P, D-1193P (all from Kraton Performance Polymers) and under the trade names For example The 4000 series SIS (from TSRC / Dexco) was commercially obtained.

[0055] According to one or more embodiments, the radiation curable adhesive composition comprises at least one styrene-isoprene-styrene (SIS) block copolymer SP1 and / or at least one styrene-butadiene-styrene (SBS) block copolymer SP2, wherein the weight ratio of the amounts of SP1 to SP2 in the adhesive composition ranges from 3:1 to 1:5, preferably from 2:1 to 1:3, more preferably from 1.5:1 to 1:2.5.

[0056] The radiation curable adhesive composition further comprises at least one tackifying resin TR.

[0057] The term "tackifying resin" as used herein refers to a resin that generally enhances the adhesion and / or tack of the adhesive composition. The term "tack" as used herein refers to the property of a substance being sticky or adhesive by simple contact. Tack can be measured, for example, as loop tack. Preferred tackifying resins are tackifying at a temperature of 25 °C.

[0058] Examples of suitable tackifying resins include natural resins, synthetic resins, and chemically modified natural resins.

[0059] Examples of suitable natural resins and chemically modified natural resins include rosin, rosin esters, phenolic resin-modified rosin esters, and terpene resins. The term "rosin" should be understood to include gum rosin, wood rosin, tall oil rosin, distilled rosin, and modified rosins, such as dimeric, hydrogenated, maleated, and / or polymerized forms of any of these rosins.

[0060] Suitable terpene resins include copolymers and terpolymers of natural terpenes, such as styrene / terpene and α-methylstyrene / terpene resins; polyterpene resins generally obtained by polymerizing terpene olefins such as the bicyclic monoterpene called pinene at moderate to low temperatures in the presence of a Friedel-Crafts catalyst; hydrogenated polyterpene resins; and phenolic resin-modified terpene resins, including their hydrogenated derivatives.

[0061] The term "synthetic resin" refers to a compound obtained by a controlled chemical reaction, such as addition polymerization or condensation polymerization, between well-defined reactants that do not themselves have resinous properties.

[0062] The monomers that can be polymerized to synthesize synthetic resins may include aliphatic monomers, alicyclic monomers, aromatic monomers, or mixtures thereof. Aliphatic monomers may include C4, C5, and C6 alkanes, olefins, and conjugated dienes. Examples of aliphatic or alicyclic monomers include butadiene, isobutylene, 1,3-pentadiene, 1,4-pentadiene, cyclopentane, 1-pentene, 2-pentene, 2-methyl-1-pentene, 2-methyl-2-butene, 2-methyl-2-pentene, isoprene, cyclohexane, 1-3-hexadiene, 1-4-hexadiene, cyclopentadiene, dicyclopentadiene, and terpenes. Aromatic monomers may include C8, C9, and C 10 Aromatic Monomers. Examples of aromatic monomers include styrene, indene, derivatives of styrene, derivatives of indene, coumarone, and combinations thereof.

[0063] Particularly suitable synthetic resins include synthetic hydrocarbon resins prepared by polymerizing a mixture of unsaturated monomers obtained as by-products of cracking natural gas liquids, gas oils, or naphthas. Synthetic hydrocarbon resins obtained from petroleum-based feedstocks are referred to herein as "hydrocarbon resins." These also include pure monomer aromatic resins, which are prepared by polymerizing an aromatic monomer feedstock that has been purified to eliminate color-causing contaminants and to precisely control the composition of the product. Hydrocarbon resins typically have a relatively low average molecular weight (Mn), for example in the range of 250-5000 g / mol, and a glass transition temperature above 0°C, preferably equal to or higher than 15°C, and more preferably equal to or higher than 30°C.

[0064] Examples of suitable hydrocarbon resins include C5 aliphatic hydrocarbon resins, mixed C5 / C9 aliphatic / aromatic hydrocarbon resins, aromatic-modified C5 aliphatic hydrocarbon resins, cycloaliphatic hydrocarbon resins, mixed C5 aliphatic / cycloaliphatic hydrocarbon resins, mixed C9 aromatic / cycloaliphatic hydrocarbon resins, mixed C5 aliphatic / cycloaliphatic / C9 aromatic hydrocarbon resins, aromatic-modified cycloaliphatic hydrocarbon resins, C9 aromatic hydrocarbon resins, polyterpene resins, copolymers and terpolymers of natural terpenes, and hydrogenated versions of the foregoing hydrocarbon resins. The designations "C5" and "C9" indicate that the monomers from which the resins are prepared are primarily hydrocarbons having 4-6 and 8-10 carbon atoms, respectively. The term "hydrogenated" includes fully, substantially, and at least partially hydrogenated resins. Partially hydrogenated resins may have, for example, a hydrogenation level of 50%, 70%, or 90%.

[0065] Preferably, the at least one tackifying resin TR is a non-functionalized tackifying resin. The term "non-functionalized tackifying resin" denotes a tackifying resin that has not been chemically modified to contain functional groups such as epoxy, silane, sulfonate, amide or anhydride groups.

[0066] According to one or more embodiments, the at least one tackifying resin TR has:

[0067] - A softening point measured by the ring and ball method according to DIN EN 1238:2011 of -65 - 185 °C, preferably 75 - 175 °C, more preferably 80 - 170 °C, and / or

[0068] - A number average molecular weight (Mn) of -150 - 5000 g / mol, preferably 250 - 3500 g / mol, more preferably 250 - 2500 g / mol, and / or

[0069] - A glass transition temperature (T g ) equal to or greater than 0 °C, preferably equal to or greater than 15 °C, more preferably equal to or greater than 25 °C, even more preferably equal to or greater than 30 °C, still more preferably equal to or greater than 35 °C, which is determined by dynamic mechanical analysis (DMA) as the peak of the loss modulus (G") curve measured using an applied frequency of 1 Hz and a strain level of 0.1%.

[0070] Suitable hydrocarbon resins are commercially available, for example, under the trade names series, Plus, Extra and STS (all from Cray Valley); under the trade names 1000 series, 2000 series and 5000 series (all from Exxon Mobile Chemical); under the trade names T series, TT series, TD series, TL series, TN series, TK series and TV series (all from Rütgers Novares GmbH); and under the trade names and (all from Eastman Chemicals) are commercially available.

[0071] According to one or more embodiments, the radiation - curable adhesive composition further comprises:

[0072] e) At least one plasticizer PL, preferably selected from processing oils and liquid polyolefin resins.

[0073] Suitable processing oils used as the plasticizer PL include at least mineral oils, synthetic oils, and vegetable oils.

[0074] The term "mineral oil" in the present disclosure refers to a hydrocarbon liquid having a lubricating viscosity (i.e., a kinematic viscosity of 1 cSt or higher at 100 °C), which is derived from petroleum crude oil and has undergone one or more refining and / or hydrotreating steps, such as fractionation, hydrocracking, dewaxing, isomerization, and hydrofining, to purify and chemically modify the components to achieve a final set of properties. In other words, the term "mineral" in the present disclosure refers to refined mineral oil, which can also be characterized as Group I - III base oils according to the classification of the American Petroleum Institute (API).

[0075] Suitable mineral oils for use as at least one plasticizer PL include paraffinic, naphthenic, and aromatic mineral oils. Particularly suitable mineral oils include paraffin oils and naphthenic oils, which contain a relatively small amount of aromatic structural moieties, such as not more than 25 wt%, preferably not more than 15 wt%, based on the total weight of the mineral oil.

[0076] The term "synthetic oil" in the present disclosure refers to a fully synthetic (polyalphaolefin) oil, which is also referred to as Group IV base oil according to the classification of the American Petroleum Institute (API). Suitable synthetic oils are prepared from liquid polyalphaolefins (PAO) obtained by polymerizing alpha-olefins in the presence of a polymerization catalyst such as a Friedel-Crafts catalyst. Generally, liquid PAO are high-purity hydrocarbons having a paraffinic structure and a high degree of side-chain branching. Particularly suitable synthetic oils include those obtained by the so-called gas-to-liquid process.

[0077] The term "liquid polyolefin resin" in the present disclosure refers to a polyolefin resin that flows at normal room temperature, i.e., has a pour point of less than 20 °C.

[0078] Suitable liquid polyolefin resins for use as at least one plasticizer PL include, for example, liquid polybutene and liquid polyisobutene (PIB). The term "liquid polybutene" in the present disclosure refers to a low-molecular-weight olefin oligomer containing isobutene and / or 1-butene and / or 2-butene. The ratio of C4-olefin isomers can vary depending on the manufacturer and grade. When the C4-olefin is only 1-butene, the material is referred to as "poly-n-butene" or "PNB". The term "liquid polyisobutene" herein refers to a low-molecular-weight olefin oligomer of isobutene, preferably containing at least 75 wt%, more preferably at least 85 wt% of repeating units derived from isobutene. Suitable liquid polybutene and polyisobutene have a number-average molecular weight (Mn) of less than 5000 g / mol, preferably less than 3500 g / mol, more preferably less than 3000 g / mol, and even more preferably less than 2500 g / mol.

[0079] Suitable liquid polybutene and polyisobutene are commercially available, for example, under the trade names such as H-300 and H - 1200 (from Ineos); under the trade name such as V230, V500 and V700 (from BASF); under the trade name such as Poly 230 (from Univar GmbH, Germany); and under the trade name such as PB 950 (from Daelim Industrial) are commercially available.

[0080] Particularly suitable liquid polybutene and liquid polyisobutene have:

[0081] - An average molecular weight (Mn) of 150 - 3500 g / mol, preferably 250 - 3000 g / mol, more preferably 350 - 2500 g / mol, and / or

[0082] - A pour point measured according to ISO 3016 in the range of - 10 to + 15 °C, preferably - 10 to + 10 °C, and / or

[0083] - A polydispersity index (Mw / Mn) measured by GPC of not more than 5, preferably in the range of 0.5 - 5.0, more preferably 1.0 - 4.5, even more preferably 1.0 - 3.5.

[0084] If used, at least one plasticizer PL preferably accounts for 5 - 45% by weight, more preferably 10 - 40% by weight, even more preferably 15 - 35% by weight of the total weight of the radiation - curable binder composition.

[0085] According to one or more embodiments, the at least one plasticizer PL comprises at least one processing oil PL1, preferably a mineral oil, more preferably a paraffinic oil or a naphthenic oil, wherein the at least one processing oil PL1 preferably accounts for at least 25% by weight, more preferably at least 50% by weight, even more preferably at least 75% by weight of the total weight of the at least one plasticizer PL.

[0086] According to one or more embodiments, the radiation - curable binder composition comprises both at least one tackifying resin TR and at least one plasticizer PL, preferably comprises at least one processing oil PL1, preferably a mineral oil, more preferably a paraffinic oil or a naphthenic oil, wherein the weight ratio of at least one tackifying resin TR to at least one processing oil PL1 is in the range of 3:1 to 1:1, preferably 2.5:1 to 1:1.

[0087] According to one or more embodiments, the radiation - curable binder composition further comprises:

[0088] f) at least one liquid rubber LR that is different from at least one plasticizer PL.

[0089] The term "liquid rubber" in the present disclosure refers to a polymer that exhibits a rubber phase or a rubber that exists in a liquid phase at room temperature (23 °C ± 3 °C). Here, the "liquid phase" means that the rubber exhibits the fluidity of the rubber itself after the solvent has been removed.

[0090] Suitable liquid rubbers include homopolymers and copolymers having at least one ethylenically unsaturated double bond per molecule, such as polybutadiene, especially 1,4- and 1,2-polybutadiene, polybutene, polyisobutene, 1,4- and 3,4-polyisoprene, styrene / butadiene copolymers, butadiene / acrylonitrile copolymers, optionally having terminal and / or (randomly distributed) lateral functional groups, such as maleic anhydride, hydroxyl or silyl groups.

[0091] Particularly suitable liquid rubbers have:

[0092] - a number average molecular weight (Mn) of 5000 - 150000 g / mol, preferably 8000 - 130000 g / mol, more preferably 12000 - 100000 g / mol, even more preferably 15000 - 80000 g / mol, and / or

[0093] - a glass transition temperature equal to or lower than 20 °C, preferably equal to or lower than 10 °C, more preferably equal to or lower than 0 °C, measured by DSC, and / or

[0094] - a viscosity of 2.5 - 2700 Pa·s, preferably 5 - 2000 Pa·s, more preferably 10 - 15000 Pa·s, measured at 23 °C according to the EN ISO 3219 standard.

[0095] Suitable liquid rubbers for radiation-curable adhesive compositions are available, for example, under the trade names series, series and series (such as LIR-30, LIR-50, LIR-200, LIR-300-series, LIR-400-series, LIR-700, LBR-300-series and L-SBR-800 series) from Kuraray. Other suitable liquid rubbers are available under the trade name from Synthomer, under the trade name from Nippon-Soda, under the trade name from Cray Valley, and under the trade name from Evonik Industries.

[0096] If used, at least one liquid rubber LR preferably accounts for 0.5 - 25% by weight, more preferably 1.5 - 20% by weight, even more preferably 2.5 - 15% by weight of the total weight of the radiation-curable adhesive composition.

[0097] In addition, the radiation-curable adhesive composition may contain additional auxiliary substances and additives, such as those selected from UV absorbers, UV and heat stabilizers, optical brighteners, pigments, dyes, and desiccants. Exemplary UV stabilizers that may be included in the hot melt adhesive composition include, for example, sterically hindered phenols. However, the total amount of such additional auxiliary substances and additives preferably does not exceed 15% by weight, more preferably does not exceed 10% by weight, even more preferably does not exceed 5% by weight of the total weight of the radiation-curable adhesive composition.

[0098] The radiation-curable adhesive composition can be prepared by mixing its components at a temperature of 140 - 220 °C, preferably 160 - 200 °C, until a homogeneously mixed mixture is obtained.

[0099] Any conventional mixing technique known to those skilled in the art can be used. Preferably, the mixing is carried out by using a kneading process. Components a) to d) and optionally components e) and f) (if used) can be added to the mixer in any order. Preferably, at least one styrene-based polymer SP is first mixed with the tackifying resin TR until a homogeneously mixed mixture is obtained. Then the remaining components can be added to the homogeneously mixed mixture in any order.

[0100] Unless otherwise specified, the preferred options given above for at least one styrene-based polymer SP, at least one tackifying resin TR, at least one photoinitiator PI, at least one crosslinking agent CA, at least one plasticizer PL, and at least one liquid rubber LR are equally applicable to all aspects of the present invention.

[0101] Another aspect of the present invention is at least partially cured adhesive obtained by subjecting the substance of the radiation-curable adhesive composition of the present invention to radiation having a wavelength of 365 - 500 nm, preferably 365 - 475 nm, more preferably 365 - 450 nm, even more preferably 365 - 415 nm to initiate the curing reaction of the radiation-curable adhesive composition.

[0102] In one or more embodiments, the substance of the radiation-curable adhesive composition is subjected to radiation having a wavelength in the range of 375 - 485 nm, preferably 380 - 475 nm, more preferably 385 - 465 nm, even more preferably 390 - 450 nm to initiate the curing reaction of the radiation-curable adhesive composition.

[0103] Another aspect of the present invention is a method for producing at least partially cured adhesive, comprising the following steps:

[0104] - A substance providing the radiation-curable adhesive composition of the present invention, and

[0105] - Subjecting the substance to radiation having a wavelength in the range of 365 - 500 nm, preferably 365 - 475 nm.

[0106] In one or more embodiments, the substance of the radiation-curable adhesive composition is subjected to radiation having a wavelength in the range of 375 - 485 nm, preferably 380 - 475 nm, more preferably 385 - 465 nm, even more preferably 390 - 450 nm, to initiate the curing reaction of the radiation-curable adhesive composition.

[0107] Another aspect of the present invention is a vibration and noise damping element (1), comprising:

[0108] i) A damping layer (2) having a first surface (3) and a second surface (3'), and

[0109] ii) An adhesive layer (4) composed of at least partially cured adhesive of the present invention and covering at least a part of the first surface (3) of the damping layer (2),

[0110] wherein the damping layer (2) contains or is composed of a sound damping material, and the sound damping material contains:

[0111] - An asphalt component BC or a polymer component PC,

[0112] - At least one hydrocarbon resin HR,

[0113] - Optionally, at least one wax W,

[0114] - Optionally, at least one plasticizer PL, and

[0115] - Based on the total weight of the sound damping material, at least 25% by weight, preferably at least 35% by weight of at least one solid particle filler F.

[0116] The cross-section of the vibration and noise damping element (1) is shown in Figure 1 in.

[0117] The asphalt component BC or the polymer component PC and various additives (including at least one hydrocarbon resin HR, at least one wax W and at least one plasticizer PL, if present in the sound damping material) form a binder matrix for at least one solid particle filler F. The amount of the binder matrix in the sound damping material is not particularly limited, but the amount should be high enough so that the components of the filler component can be effectively bonded and prevent the formation of an interconnected solid network of solid particle compounds.

[0118] The sound damping material comprises at least 25% by weight, preferably at least 35% by weight, more preferably at least 45% by weight of at least one solid particulate filler F, based on the total weight of the sound damping material.

[0119] According to one or more embodiments, the sound damping material comprises 25 - 75% by weight, preferably 35 - 70% by weight, more preferably 40 - 70% by weight, even more preferably 45 - 70% by weight, still more preferably 45 - 65% by weight of at least one solid particulate filler F, based on the total weight of the sound damping material.

[0120] The at least one solid particulate filler F preferably has a d 90 particle size of not more than 2.5 mm, more preferably not more than 1.5 mm and / or a water solubility of less than 0.1 g / 100 g water at a temperature of 20 °C, more preferably less than 0.05 g / 100 g water, even more preferably less than 0.01 g / 100 g water.

[0121] The term "particle size" in the present disclosure refers to the area equivalent spherical diameter of the particles (X 面积 ). The term "median particle size d 50 " refers to the particle size at which 50% by volume of all the particles is less than the d 50 value. Similarly, the term d 90 particle size in the present disclosure refers to the particle size at which 90% by volume of all the particles is less than the d 90 value. The particle size distribution can be measured by laser diffraction according to the method described in standard ISO 13320:2009 using a wet or dry dispersion method and, for example, a Mastersizer 2000 device (a trademark of Malvern Instruments Ltd, GB).

[0122] According to one or more embodiments, the at least one solid particulate filler F is selected from calcium carbonate, magnesium carbonate, talc, kaolin, diatomaceous earth, wollastonite, feldspar, montmorillonite, dolomite, silica, cristobalite, iron oxide, iron nickel oxide, strontium ferrite, barium - strontium ferrite, hollow ceramic spheres, hollow glass spheres, hollow organic spheres, glass spheres, mica, barium sulfate and graphite.

[0123] It may be preferred that the sound damping material comprises several different fillers, for example at least two different fillers. For example, some fillers can be used to improve the sound damping performance of the sound damping material, while other fillers can be used to enable the sound damping material to adhere magnetically to a metal substrate or to reduce the weight of the sound damping material.

[0124] Preferably, the sum of the amounts of the bitumen component BC, the polymer component PC, at least one hydrocarbon resin HR, at least one wax W and at least one plasticizer PL (if present in the sound damping material) accounts for no more than 70% by weight, preferably no more than 65% by weight, more preferably no more than 60% by weight of the total weight of the sound damping material.

[0125] According to one or more embodiments, the sum of the amounts of the bitumen component BC, the polymer component PC, at least one hydrocarbon resin HR, at least one wax W and at least one plasticizer PL (if present in the sound damping material) accounts for 15 - 65% by weight, preferably 20 - 60% by weight, more preferably 20 - 55% by weight, even more preferably 25 - 50%, most preferably 25 - 45% by weight of the total weight of the sound damping material.

[0126] Examples of suitable hydrocarbon resins to be used as at least one hydrocarbon resin HR include C5 aliphatic resins, mixed C5 / C9 aliphatic / aromatic resins, aromatic-modified C5 aliphatic resins, alicyclic resins, mixed C5 aliphatic / alicyclic resins, mixed C9 aromatic / alicyclic resins, mixed C5 aliphatic / alicyclic / C9 aromatic resins, aromatic-modified alicyclic resins, C9 aromatic resins and hydrogenated forms of the above resins. The symbols "C5" and "C9" indicate that the monomers for preparing the resin are mainly hydrocarbons having 4 - 6 and 8 - 10 carbon atoms respectively. The term "hydrogenated" includes fully, substantially and at least partially hydrogenated resins. Partially hydrogenated resins may have, for example, a hydrogenation level of 50%, 70% or 90%.

[0127] The type of at least one hydrocarbon resin HR is not particularly limited in the present invention. The selection of at least one hydrocarbon resin HR depends at least in part on the type of other components contained in the binder matrix of the sound damping material, especially the type of the polymer component PC.

[0128] According to one or more embodiments, at least one hydrocarbon resin HR has:

[0129] - a softening point of at least 70 °C, preferably at least 80 °C, more preferably 70 - 180 °C, preferably 80 - 170 °C, more preferably 100 - 160 °C, determined by the ring and ball method as defined in DIN EN 1238:2011, and / or

[0130] - an average molecular weight (Mn) of 250 - 7500 g / mol, preferably 300 - 5000 g / mol, and / or

[0131] - a glass transition temperature (T g), the glass transition temperature (T g ) is determined by dynamic mechanical analysis (DMA) as the peak of the loss modulus (G″) curve measured using an applied frequency of 1 Hz and a strain level of 0.1%.

[0132] Suitable hydrocarbon resins are commercially available, for example, under the trade names Series, Plus, Extra and STS (all from Cray Valley); under the trade names 1000 Series, 2000 Series and 5000 Series (all from Exxon Mobile Chemical); under the trade names T Series, TT Series, TD Series, TL Series, TN Series, TK Series and TV Series (all from Rütgers Novares GmbH); and under the trade names and (all from Eastman Chemicals) are commercially available.

[0133] According to one or more embodiments, the sound damping material further comprises at least one wax W.

[0134] The term "wax" as used herein refers to a substance having a waxy consistency and having a melting temperature or melting temperature range above normal room temperature, particularly above 25 °C.

[0135] Suitable waxes to be used as the at least one wax particularly include synthetic waxes, such as petroleum waxes, such as paraffin wax, petrolatum and microcrystalline wax, polyolefin waxes, polyethylene glycol waxes (Carbowax), amide waxes and chemically modified waxes, such as hardened or hydrogenated waxes, such as Montan ester waxes.

[0136] According to one or more embodiments, the at least one wax W is selected from polyolefin waxes, paraffin wax, microcrystalline wax and amide wax.

[0137] According to one or more embodiments, the at least one wax W has:

[0138] - The softening point determined by the ring and ball method defined in DIN EN 1238:2011 is 75 °C - 180 °C, preferably 80 °C - 160 °C, more preferably 85 °C - 140 °C, and / or

[0139] - The melt viscosity determined at a temperature of 170 °C according to DIN 53019-1:2008 standard in the range of 10 - 10000 mPa·s, preferably 100 - 5000 mPa·s, more preferably 500 - 3500 mPa·s. The melt viscosity can be determined by using a rotational viscometer at 5 revolutions per minute, for example, by using a Brookfield DV-2 Thermosel viscometer with a No. 27 spindle.

[0140] According to one or more embodiments, at least one wax is a polyolefin wax. The term "polyolefin wax" as used herein refers to a low molecular weight polymer of linear or branched α-olefins having 2 to 30 carbon atoms and a number average molecular weight (Mn) of 5000 - 25000 g / mol. They include homopolymers and copolymers of the above-mentioned linear or branched α-olefins. Polyolefin waxes can be obtained by thermal decomposition of polyolefin plastics, especially polyethylene plastics, or by direct polymerization of olefins. Suitable polymerization methods include, for example, free radical methods in which olefins (such as ethylene) react at high pressure and high temperature to obtain more or less branched waxes, and methods in which ethylene and / or higher α-olefins (especially propylene) are polymerized using organometallic catalysts (such as Ziegler-Natta or metallocene catalysts) to obtain unbranched or branched waxes. Polyolefin waxes generally have at least a partially crystalline structure.

[0141] According to one or more embodiments, at least one wax W is paraffin wax, preferably Fischer-Tropsch wax. The term "paraffin wax" as used in this disclosure refers to a hard, crystalline wax mainly composed of saturated paraffins. Paraffin waxes are usually obtained from petroleum distillates or derived from mineral oils of the mixed base or paraffinic base type.

[0142] According to one or more embodiments, at least one wax W is an amide wax. The term "amide wax" as used herein refers to a wax containing an amide bond (-CONH-) in the molecule or an amide group (-CONH2) at the molecular end. According to one or more embodiments, at least one wax W is an amide wax selected from N,N'-ethylene bis(stearamide), stearic acid amide, N,N'-methylene bis(stearamide), and hydroxymethyl stearamide.

[0143] According to a first preferred embodiment, the sound damping material of the damping layer (2) comprises:

[0144] b1) 25 - 65 wt%, preferably 35 - 55 wt% of an asphalt component BC,

[0145] b2) 0 - 10 wt%, preferably 0.25 - 5 wt% of at least one hydrocarbon resin HR, and

[0146] b3) 0 - 10 wt%, preferably 0.25 - 7.5 wt% of at least one wax W, all ratios being based on the total weight of the sound damping material.

[0147] The sound damping material according to the first preferred embodiment can be characterized as an "asphalt-based damping material".

[0148] The term "asphalt" in the present disclosure denotes a blend of heavy hydrocarbons having a solid consistency at room temperature. These are typically obtained as vacuum residues from refinery processes, which can be distillation (topping or vacuum) and / or conversion processes of suitable crude oils, such as thermal cracking and visbreaking. Additionally, the term "asphalt" also denotes natural and synthetic asphalts and asphalt materials obtained from the extraction of tar and bitumen sands.

[0149] The asphalt component BC can include one of a variety of different types of asphalt materials, such as penetration grade (distilled) asphalt, air-blown (semi-blown) asphalt, and hard grade asphalt.

[0150] The term "penetration grade asphalt" herein refers to asphalt obtained by the fractional distillation of crude oil. The heavy fraction consisting of high molecular weight hydrocarbons obtained after removing the gasoline, kerosene, and gas oil fractions (also known as long residue) is first distilled in a vacuum distillation column to produce more gas oil, distillate, and short residue. The short residue is then used as a raw material for producing different grades of asphalt classified by their penetration index, which is typically defined by the PEN value, which is the distance in tenths of a millimeter (dmm) that a needle penetrates the asphalt under a standard test method. Penetration grade asphalt is characterized by its penetration value and softening point. The term "air-blown asphalt" or "air-refined asphalt" in the present disclosure refers to asphalt that has undergone mild oxidation in order to produce asphalt that meets the specifications for paving grade asphalt. The term "hard grade asphalt" in the present disclosure refers to asphalt produced from propane-precipitated asphalt using extended vacuum distillation with some air blowing. Hard asphalt typically has a low penetration value and a high softening point.

[0151] According to one or more embodiments, the asphalt component BC comprises at least 75 wt%, preferably at least 85 wt%, more preferably at least 90 wt% of at least one penetration grade asphalt, preferably having a penetration value of 15 - 50 dmm, more preferably 20 - 45 dmm and / or a softening point determined by the ring and ball method according to DIN EN 1238:2011 standard of 40 - 125 °C, preferably 50 - 100 °C.

[0152] In the case of asphalt-based damping materials, the sound damping material preferably further comprises at least one modifying polymer MP for the asphalt component BC.

[0153] Suitable polymers for use as at least one modifying polymer MP include, for example, atactic polypropylene (APP), amorphous polyolefins (APO), styrene block copolymers, and elastomers. The term "amorphous polyolefin" refers to olefins having a low crystallinity (e.g., in the range of 0.001 - 10 wt%, preferably 0.001 - 5 wt%) as determined by measurement using differential scanning calorimetry (DSC). The crystallinity of the polymer can be determined by measuring the heat of fusion using differential scanning calorimetry performed according to the ISO 11357-3:2018 standard, from which the crystallinity is calculated. In particular, the term "amorphous polyolefin" refers to poly-α-olefins lacking a crystalline melting point (Tm) as determined by differential scanning calorimetry (DSC) or equivalent techniques.

[0154] Suitable amorphous polyolefins for use as at least one modifying polymer MP include, for example, atactic polypropylene, amorphous propylene-rich copolymers of propylene and ethylene, amorphous propylene-rich copolymers of propylene and butene, amorphous propylene-rich copolymers of propylene and hexene, and amorphous propylene-rich terpolymers of propylene, ethylene, and butene. The term "propylene-rich" should be understood to mean copolymers and terpolymers having a content of propylene-derived units of at least 50 wt%, preferably at least 65 wt%, more preferably at least 70 wt% based on the total weight of the copolymer / terpolymer.

[0155] Suitable styrene block copolymers for use as at least one modifying polymer MP particularly include SXS-type block copolymers, where S represents an inelastic styrene (or polystyrene) block and X represents an elastomeric α-olefin block, which can be polybutadiene, polyisoprene, polyisoprene-polybutadiene, fully or partially hydrogenated polyisoprene (ethylene-propylene), or fully or partially hydrogenated polybutadiene (ethylene-butene). The elastomeric α-olefin block preferably has a glass transition temperature of -55°C to -35°C. The elastomeric α-olefin block can also be a chemically modified α-olefin block. Particularly suitable chemically modified α-olefin blocks include, for example, maleic acid-grafted α-olefin blocks, especially maleic acid-grafted ethylene-butene blocks. Preferred styrene block copolymers for use as at least one modifying polymer MP include SBS, SIS, SIBS, SEBS, and SEPS block copolymers, particularly SBS block copolymers, preferably having a linear, radial, diblock, triblock, or star structure.

[0156] Suitable elastomers for use as at least one modified polymer MP include, for example, styrene-butadiene rubber (SBR), ethylene propylene diene monomer rubber (EPDM), polyisoprene, polybutadiene, natural rubber, polychloroprene rubber, ethylene-propylene rubber (EPR), nitrile rubber, and acrylic rubber.

[0157] According to one or more embodiments, at least one modified polymer MP is selected from atactic polypropylene (APP), amorphous polyolefin (APO), styrene block copolymer, styrene-butadiene rubber (SBR), ethylene propylene diene monomer rubber (EPDM), polyisoprene, polybutadiene, natural rubber, polychloroprene rubber, ethylene-propylene rubber (EPR), nitrile rubber, and acrylic rubber.

[0158] According to one or more embodiments, based on the total weight of the asphalt-based damping material, at least one modified polymer MP is present in the asphalt-based damping material in an amount of 0.5 - 10% by weight, preferably 1 - 7.5% by weight.

[0159] In the case of an asphalt-based damping material, it is preferred that the sound damping material is substantially free of crosslinking agents / curing agents, such as free radical crosslinking agents, such as peroxides. The phrase "substantially free of" means that if a certain amount of crosslinking agent is present in the sound damping material, the amount is negligible such that the effect of the crosslinking agent cannot be obtained. In other words, the amount of crosslinking agent present in the sound damping material cannot initiate the curing of the polymer components, especially at least one modified polymer MP, or can only initiate a substantially negligible amount of crosslinking.

[0160] According to one or more embodiments, based on the total weight of the asphalt-based damping material, the asphalt-based damping material contains less than 0.15% by weight, preferably less than 0.1% by weight, more preferably less than 0.01% by weight, and even more preferably 0% by weight of crosslinking agent / curing agent.

[0161] According to a second preferred embodiment, the sound damping material of the damping layer (2) comprises:

[0162] - 0.5 - 25% by weight, preferably 1.5 - 20% by weight of a polymer component PC comprising at least one thermoplastic polymer TP,

[0163] - 2.5 - 35% by weight, preferably 5 - 30% by weight of at least one hydrocarbon resin HR,

[0164] - 0 - 15% by weight, preferably 0.5 - 10% by weight of at least one wax W, and

[0165] - 0 - 30% by weight, preferably 0.5 - 15% by weight of at least one plasticizer PL, all proportions being based on the total weight of the sound damping material.

[0166] The sound damping material according to the second preferred embodiment can be characterized as an "asphalt-free thermoplastic damping material".

[0167] In the case of an asphalt-free thermoplastic damping material, the polymer component PC comprises at least one thermoplastic polymer TP, and the part of the asphalt component BC in the binder matrix has been optionally replaced by a specific combination of at least one thermoplastic polymer TP, at least one hydrocarbon resin HR, at least one wax W and at least one plasticizer PL added to the binder matrix. It has been found that using such a binder matrix can provide an asphalt-free thermoplastic damping material that can be processed into shaped articles using conventional thermoplastic processing methods such as extrusion, calendering, injection molding and hot pressing techniques.

[0168] According to one or more embodiments, based on the total weight of the asphalt-free thermoplastic damping material, the asphalt-free thermoplastic damping material contains less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight, and even more preferably less than 0.01% by weight of asphalt.

[0169] The composition of the polymer component PC of the asphalt-free thermoplastic damping material is preferably selected such that the temperature range of the maximum vibration damping effect of the damping material coincides with the temperature range that the surface of the substrate to be damped vibrates through during its use.

[0170] Since the ability of a polymer to dissipate thermal energy vibrations is at its maximum when the polymer is in the transition state between the hard / glass state and the soft / rubber state, the glass transition temperature (T g ) of the preferred thermoplastic polymer TP to be used in the asphalt-free thermoplastic damping material falls within the expected application temperature range. For example, in the case where the asphalt-free thermoplastic damping material is used to damp vibrations and noise in a motor vehicle structure, the application temperature is typically -40°C to 60°C, especially -35°C to 50°C. On the other hand, the softening point (T s ) and / or the melting temperature (T m ) of the preferred thermoplastic polymer TP to be used in the polymer component PC is higher than the highest application temperature of the asphalt-free thermoplastic damping material.

[0171] According to one or more embodiments, at least one thermoplastic polymer TP has:

[0172] - a glass transition temperature (T g ) below 25°C, preferably below 5°C, more preferably below 0°C, and the glass transition temperature (T g)The peak of the loss modulus (G") curve measured by dynamic mechanical analysis (DMA) at an applied frequency of 1 Hz and a strain level of 0.1%, and / or

[0173] - The softening point (T determined by the ring and ball method according to the standard DIN EN 1238:2011 above 35 °C, preferably above 45 °C, more preferably above 55 °C, for example in the range of 35 - 250 °C, preferably 45 - 200 °C, more preferably 55 - 180 °C s ).

[0174] According to one or more embodiments, the polymer component PC consists of at least one thermoplastic polymer TP.

[0175] In sound damping applications, it is generally desirable to maximize the width of the temperature range in which the vibration and noise damping effects of the sound damping material are greatest, in particular the width of the temperature range in which the measured loss factor value of the damping material is greater than 0.1. Since the maximum vibration damping effect of thermoplastic polymers usually occurs in a narrow temperature range, i.e., when the polymer is in its transition state, it may be preferred that the asphalt-free thermoplastic damping material contains at least two different thermoplastic polymers with different glass transition temperatures (T g ).

[0176] Furthermore, it may be advantageous that the at least two different thermoplastic polymers are not completely miscible with each other and / or the at least two different thermoplastic polymers can be mixed with each other to form a semi-compatible polymer blend containing micro-incompatible phases. Polymers are "completely miscible" with each other means that a polymer blend composed of at least two thermoplastic polymers has a negative Gibbs free energy and heat of mixing. A polymer blend composed of completely miscible polymers tends to have a single glass transition temperature (T measured by using dynamic mechanical analysis (DMA) g ).

[0177] According to one or more embodiments, at least one thermoplastic polymer TP comprises:

[0178] - At least one rigid thermoplastic polymer TP1, preferably at least one rigid ethylene-vinyl acetate copolymer, which has a melt flow index (MFI) of no more than 50 g / 10 min, preferably no more than 35 g / 10 min, more preferably no more than 25 g / 10 min, even more preferably no more than 15 g / 10 min, still more preferably no more than 10 g / 10 min determined according to ISO 1133 (190 °C / 2.16 kg) and / or has a glass transition temperature (T below 5 °C, preferably below 0 °C, more preferably below -10 °C, even more preferably below -20 °C g), the glass transition temperature (T g ) is determined by dynamic mechanical analysis (DMA) as the peak of the loss modulus (G") curve measured using an applied frequency of 1 Hz and a strain level of 0.1%, and / or

[0179] - at least one soft thermoplastic polymer TP2, preferably at least one soft ethylene-vinyl acetate copolymer, which has a melt flow index (MFI) of at least 75 g / 10 min, preferably at least 100 g / 10 min, more preferably at least 150 g / 10 min, even more preferably at least 200 g / 10 min, most preferably at least 250 g / 10 min as determined according to ISO 1133 (190 °C / 2.16 kg) and / or has a glass transition temperature (T g ) below 5 °C, preferably below -0 °C, more preferably below -10 °C, even more preferably below -20 °C, and the glass transition temperature (T g ) is determined by dynamic mechanical analysis (DMA) as the peak of the loss modulus (G″) curve measured using an applied frequency of 1 Hz and a strain level of 0.1%.

[0180] In the published patent application WO 2021 / 009241 A1, examples of suitable asphalt-free thermoplastic damping materials for the damping element of the present invention are disclosed, particularly on pages 9 - 30 of said patent application.

[0181] According to a third preferred embodiment, the sound damping material of the damping layer (2) comprises:

[0182] - 0.5 - 20% by weight, preferably 2.5 - 15% by weight of a polymer component PC comprising at least one elastomer E,

[0183] - 0.5 - 35% by weight, preferably 2.5 - 25% by weight of at least one hydrocarbon resin HR,

[0184] - 0 - 15% by weight, preferably 0.5 - 10% by weight of at least one wax W, and

[0185] - 0 - 30% by weight, preferably 0.5 - 25% by weight of at least one plasticizer PL, all proportions being based on the total weight of the sound damping material.

[0186] The sound damping material according to the third preferred embodiment can be characterized as an "asphalt-free elastic damping material".

[0187] According to one or more embodiments, based on the total weight of the asphalt-free elastic damping material, the asphalt-free elastic damping material contains less than 1% by weight, preferably less than 0.5% by weight, more preferably less than 0.1% by weight, even more preferably less than 0.01% by weight of asphalt.

[0188] According to one or more embodiments, at least one elastomer E is selected from butyl rubber, halogenated butyl rubber, ethylene-propylene-diene monomer rubber, natural rubber, chloroprene rubber, synthetic 1,4-cis-polyisoprene, polybutadiene rubber, ethylene-propylene rubber, styrene-butadiene rubber, isoprene-butadiene rubber, styrene-isoprene-butadiene rubber, acrylonitrile-isoprene rubber, and acrylonitrile-butadiene rubber, preferably selected from butyl rubber, halogenated butyl rubber, ethylene-propylene-diene monomer rubber, chloroprene rubber, synthetic 1,4-cis-polyisoprene, polybutadiene rubber, and ethylene-propylene rubber.

[0189] The term "butyl rubber" as used herein denotes a polymer derived from a monomer mixture containing a major portion of C4-C7 monoolefin monomers, preferably isolefin monomers, and a minor portion, such as not more than 30 wt% of C4-C 14 polyolefin monomers, preferably conjugated dienes. Preferred C4-C7 monoolefin monomers may be selected from isobutene, 2-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2-butene, 4-methyl-1-pentene, and mixtures thereof.

[0190] Preferred C4-C 14 polyolefins contain C4 to C 10 conjugated dienes. Preferred C4 to C 10 conjugated dienes may be selected from isoprene, butadiene, 2,4-dimethylbutadiene, piperylene, 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.

[0191] According to one or more embodiments, based on the total weight of the asphalt-free elastomeric damping material, the asphalt-free elastomeric damping material contains 3-15 wt%, preferably 3.5-12.5 wt%, more preferably 5-12.5 wt% of at least one elastomer E.

[0192] According to one or more embodiments, in addition to at least one elastomer E, the polymer component PC further contains at least one thermoplastic polymer TMP, which is preferably selected from polyolefin homopolymers and copolymers, copolymers of ethylene and vinyl acetate, and thermoplastic olefin elastomers (TPE-O).

[0193] The preferred options given above for at least one thermoplastic polymer TP used in the asphalt-free thermoplastic damping material also apply to at least one thermoplastic polymer TMP used in the asphalt-free elastomeric damping material.

[0194] According to one or more embodiments, the weight ratio of the amount of at least one elastomer E to the amount of at least one thermoplastic polymer TMP is in the range of 10:1 to 1:3, preferably 5:1 to 1:2, more preferably 5:1 to 1:1.

[0195] According to one or more embodiments, the asphalt-free elastic damping material further comprises a vulcanization system VS.

[0196] A large number of sulfur-based vulcanization systems and sulfur-free vulcanization systems are suitable.

[0197] In the case of using a sulfur-based vulcanization system, the vulcanization system VS preferably contains powdered sulfur, more preferably at least one sulfur compound selected from powdered sulfur, precipitated sulfur, highly-dispersed sulfur, surface-treated sulfur, and insoluble sulfur.

[0198] The preferred sulfur-based vulcanization system contains 1-15% by weight, more preferably 5-10% by weight of powdered sulfur, preferably at least one sulfur compound selected from powdered sulfur, precipitated sulfur, highly-dispersed sulfur, surface-treated sulfur, and insoluble sulfur, based on the total weight of the vulcanization system.

[0199] According to one or more embodiments, the vulcanization system VS is a sulfur-free vulcanization system.

[0200] The preferred sulfur-free vulcanization system contains at least one vulcanizing agent and optionally at least one organic vulcanization accelerator and / or at least one inorganic vulcanization accelerator.

[0201] Suitable vulcanizing agents for sulfur-free vulcanization systems include, for example, organic peroxides, phenolic resins, bisazidoformates, polyfunctional amines, p-quinone dioxime, p-benzoquinone dioxime, para-quinone dioxime dibenzoate, p-nitrosobenzene, dinitrosobenzene, thiuram compounds, bismaleimides, dithiols, zinc oxide, and vulcanization systems crosslinked with (blocked) diisocyanates.

[0202] Suitable organic vulcanization accelerators to be used in sulfur-free vulcanization systems include thiocarbamates, dithiocarbamates (in the form of their ammonium or metal salts), xanthates, thiuram compounds (monosulfides and disulfides), thiazole compounds, aldehyde-amine accelerators such as hexamethylenetetramine, and guanidine accelerators.

[0203] Suitable inorganic vulcanization accelerators to be used in sulfur-free vulcanization systems include, for example, zinc compounds, especially zinc salts of fatty acids, basic zinc carbonate, and zinc oxide.

[0204] According to one or more embodiments, the vulcanization system VS is a vulcanization system free of elemental sulfur, preferably containing at least one vulcanizing agent selected from p-quinone dioxime, p-benzoquinone dioxime, p-quinone dioxime dibenzoate, p-nitrosobenzene, dinitrosobenzene, and thiuram compounds, preferably selected from p-quinone dioxime, p-benzoquinone dioxime, p-quinone dioxime dibenzoate, tetramethylthiuram disulfide (TMTD), and tetrabenzylthiuram disulfide (TBzTD), and preferably further containing at least one organic vulcanization accelerator and / or at least one inorganic vulcanization accelerator.

[0205] According to one or more embodiments, at least one organic vulcanization accelerator is selected from cyclohexylbenzothiazole sulfonamide, mercaptobenzothiazole sulfide (MBTS), diphenylguanidine, and zinc dimethyldithiocarbamate.

[0206] According to one or more embodiments, at least one inorganic vulcanization accelerator is selected from zinc salts of fatty acids, basic zinc carbonate, and zinc oxide, more preferably zinc oxide.

[0207] According to one or more embodiments, based on the total weight of the asphalt-free elastic damping material, the asphalt-free elastic damping material contains 1-15% by weight, more preferably 1-12.5% by weight, even more preferably 2-10% by weight, and most preferably 3.5-10% by weight of the vulcanization system VS free of elemental sulfur.

[0208] The sound damping material as described above may optionally contain additives that are conventional for sound damping materials. Examples of suitable additives include, for example, pigments, thixotropic agents, heat stabilizers, desiccants, and flame retardants. If used, these additives preferably account for no more than 25% by weight, more preferably no more than 15% by weight, and even more preferably no more than 10% by weight of the total weight of the sound damping material.

[0209] According to one or more embodiments, the damping layer (2) of the damping element has a maximum thickness of 0.5-15 mm, preferably 1-10 mm, more preferably 1.5-7.5 mm, and even more preferably 1.5-5 mm and / or a mass per unit area of 1-5 kg / m 2 , preferably 1-4.5 kg / m 2 , more preferably 1.5-4.5 kg / m 2 , still more preferably 1.5-3.5 kg / m 2 .

[0210] Preferably, the adhesive layer (4) of the damping element has a thickness of at least 50 μm, preferably at least 100 μm, more preferably at least 150 μm, and even more preferably at least 200 μm.

[0211] It has been found that such an adhesive layer provides sufficient bonding strength in typical automotive damping applications.

[0212] Another subject of the present invention is a method for producing vibration and noise damping elements, the method comprising the following steps:

[0213] (i) providing a damping layer (2) composed of the sound damping material as described above,

[0214] (ii) providing a film of the radiation-curable adhesive composition according to the present invention on the first surface (3) of the damping layer (2),

[0215] (iii) subjecting the adhesive film to radiation having a wavelength in the range of 365 - 500 nm, 365 - 475 nm, preferably 365 - 450 nm, more preferably 365 - 415 nm to effect at least partial curing of the radiation-curable adhesive composition, and

[0216] (iv) optionally, cutting the element obtained from step (iii) into a predetermined size, such as length and / or width.

[0217] In one or more embodiments, the adhesive film is subjected to radiation having a wavelength in the range of 375 - 485 nm, preferably 380 - 475 nm, more preferably 385 - 465 nm, even more preferably 390 - 450 nm to effect at least partial curing of the radiation-curable adhesive composition.

[0218] The damping layer (2) of the damping element can be provided by mixing the components of the sound damping material at an elevated temperature until a homogeneously mixed mixture is obtained, and then processing the homogeneously mixed mixture into the form of a shaped article.

[0219] The term "homogeneously mixed mixture" in the present disclosure refers to a composition in which the individual components are substantially uniformly distributed in the composition. Furthermore, a homogeneously mixed mixture can be a multiphase mixture. For example, a homogeneously mixed mixture of a polymer component and a filler component thus refers to a composition in which the components of the filler phase are homogeneously / uniformly distributed in the polymer phase. It will be clear to the person skilled in the art that within such a mixed composition, regions can be formed in which the concentration of one of the components is slightly higher than in other regions, and a 100% uniform distribution of all components cannot generally be achieved. However, according to the present invention, the term "homogeneously mixed mixture" is also intended to include such mixed compositions with an "imperfect" distribution of components.

[0220] Any conventional type of mixing device can be used to mix the components of the sound damping material. The mixing step can be carried out as an intermittent method using a conventional batch mixer such as a Dreis mixer, a Brabender mixer, a Banbury mixer or a roll mixer, or as a continuous method using a continuous mixer such as an extruder, especially a single-screw extruder, a twin-screw extruder or a planetary roll extruder. It may be advantageous to heat the components before or during mixing by applying an external heat source or by the friction generated during the mixing process itself, in order to facilitate the processing of the components into a uniformly mixed mixture by reducing the viscosity and / or melting of the individual components.

[0221] The uniformly mixed mixture of the components of the sound damping material can then be processed into the form of a shaped article by using any conventional technique (such as extrusion, blow molding, injection molding, compression molding, calendering or thermocompression techniques).

[0222] Step (ii) is preferably carried out as follows: providing the radiation-curable adhesive composition in a molten state and applying the molten adhesive composition to the first surface of the damping layer using any conventional technique, such as by using slot die coating, roll coating, extrusion coating, calendering coating or spraying.

[0223] The adhesive film is then subjected to a dose of radiation, which can be provided by using one or more lamps (such as LED lamps). The required radiation dose mainly depends on the thickness of the adhesive film, the required degree of crosslinking and the detailed composition of the adhesive.

[0224] The dose of radiation energy provided to the adhesive film can be controlled by adjusting the radiation intensity and the exposure time. The radiation intensity can be controlled by adjusting the power supplied to each lamp and the distance between the lamp and the surface of the adhesive film.

[0225] Optional step (iv) can be carried out by using any conventional technique known to those skilled in the art, such as by stamping or die-cutting.

[0226] Another subject of the present invention is a method of providing a damped system, comprising the following steps:

[0227] I) providing the vibration and noise damping element (1) as described above, and

[0228] II) bringing the outer major surface of the adhesive layer (4) into contact with the noise-emitting surface (7) of the substrate (6), and applying sufficient pressure to form an adhesive bond between the first surface (3) of the damping layer (2) and the noise-emitting surface (7).

[0229] The term "outer major surface" of the adhesive layer refers to the major surface of the adhesive layer on the side opposite to the side of the damping layer.

[0230] The substrate having a noise-emitting surface can be any type of shaped article, such as a panel, sheet or film made of, for example, metal, plastic or fiber-reinforced plastic.

[0231] According to one or more embodiments, the noise-emitting surface is an oily surface, preferably an oily metal surface.

[0232] According to one or more embodiments, the substrate is part of the structure of a motor vehicle or a white good.

[0233] Another subject of the present invention is a damping system, which comprises a substrate (6) having a noise-emitting surface (7) and a vibration and noise damping element (1) as described above, wherein at least a part of the first surface (3) of the damping layer (2) is adhesively bonded to the noise-emitting surface (7) via the adhesive layer (4), and wherein the substrate (6) having the noise-emitting surface (7) is preferably part of the structure of a motor vehicle or a white good.

[0234] Figure 2 The cross-section of the vibration damping system is shown.

[0235] According to one or more embodiments, the substrate having a noise-emitting surface is part of the structure of a motor vehicle or a white good. Specific embodiments

[0236] Examples

[0237] In the examples, the following compounds and products shown in Table 1 were used.

[0238] Table 1

[0239]

[0240]

[0241] Preparation of the radiation-curable adhesive composition

[0242] First, a plasticizer (PL) was added to a mixer and heated to a temperature of 180 °C. Then tackifying resins (TR) and polymers (SP1, SP2) were added, and mixing was continued at a temperature above 160 °C. Finally, a photoinitiator (PI) and a crosslinking agent (CA) were added to the mixer, and mixing was continued until a homogeneously mixed mixture was obtained.

[0243] Heat resistance (thermal stability under static load)

[0244] Coating an asphalt-based damping layer with the radiation-curable adhesive composition and cut into specimens with a width of 7 cm and a length of 16 cm. Use a hot melt coater to coat the adhesive composition at a coating weight of 50 g / m 2 . After application, cure the adhesive film using an IIST HANDCURE system with an emission spectrum of 365 - 415 nm.

[0245] Bond the obtained self - adhesive asphalt - based damping sample to a sample of EPD (electrophoretic deposition) steel plate. Use the specimen obtained by bonding the asphalt - based damping layer sample to the EDP steel plate using a double - sided adhesive tape (S - 4705MF, from ATP) as a reference example. The double - sided adhesive tape has two layers of acrylic pressure - sensitive adhesive with a coating weight of 50 g / m 2 .

[0246] Hang the specimen vertically from one end on a metal hook and place it in an oven. In the measurement of thermal stability, heat - treat the specimen at a temperature of 160 °C for 30 minutes. If no bond failure occurs before the end of the heat - treatment, record the result of the heat - resistance test as "pass".

[0247] The composition of the tested adhesive composition and the length of the radiation treatment required to pass the heat - resistance test are shown in Table 2 below.

[0248] Roll peel strength

[0249] First, coat an aluminum foil with a thickness of 0.15 mm with the tested radiation - curable adhesive composition. Use an IST HANDCURE system with an emission spectrum of 365 - 415 nm to keep the adhesive film uncured or radiation - cured for 6 seconds.

[0250] Cut a sample strip with a width of 30 mm from the adhesive - coated aluminum foil and adhere it to the EPD steel plate with a length of about 12 cm, and roll it twice in two directions with a standard FINAT roller. Before measuring the peel strength, store the composite specimen at normal room temperature (RT) or 160 °C for 30 minutes. Measure the roll peel strength at a peel angle of 90 o ° and a constant cross - head speed of 100 mm / min over a length of 10 cm. Record the obtained peel strength as force / substrate width (N / cm).

[0251] Initial tack

[0252] Determine the initial tack using an aluminum foil with a film of the tested radiation - curable adhesive composition.

[0253] The aluminum foil was fixed to the Anton Paar MCR 302 device using the software RheoCompass V1.30 and a plate geometry with a diameter of 8 mm. The geometry was moved downwards at a constant speed of 10 μm / s until a constant normal force of 1 N was reached. The measurement system was then moved upwards from the sample at a constant removal speed of 20 μm / s. Each sample was measured 5 times and the average value of the minimum force was recorded.

[0254] Table 2

[0255]

[0256]

[0257] * S-4705MF (from ATP)

[0258] **Curing time required to pass the heat resistance test.

Claims

1. A radiation-curable adhesive composition comprising: a) at least one styrene-based polymer SP, b) at least one tackifying resin TR, c) at least one photoinitiator PI, and d) at least one crosslinking agent CA, wherein the at least one photoinitiator PI can be activated by radiation having a wavelength of 365 - 500 nm to initiate the curing reaction of the adhesive composition.

2. The radiation-curable adhesive composition according to claim 1, wherein the at least one photoinitiator PI can be activated by radiation having a wavelength of 365 - 475 nm, preferably 365 - 415 nm, to initiate the curing reaction of the adhesive composition.

3. The radiation-curable adhesive composition according to any one of the preceding claims, wherein the at least one crosslinking agent CA has at least three thiol groups, preferably at least four thiol groups and / or a number average molecular weight (Mn) of 150 - 1500 g / mol, preferably 350 - 1000 g / mol, as determined by gel permeation chromatography using polystyrene as a standard sample.

4. The radiation-curable adhesive composition according to any one of the preceding claims, comprising 10 - 50% by weight, preferably 15 - 40% by weight, of the at least one styrene-based polymer SP, based on the total weight of the adhesive composition.

5. The radiation-curable adhesive composition according to any one of the preceding claims, comprising: a) 10 - 50% by weight, preferably 15 - 40% by weight, of at least one styrene-based polymer SP, b) 15 - 65% by weight, preferably 25 - 60% by weight, of at least one tackifying resin TR, c) 0.25 - 5% by weight, preferably 0.5 - 3.5% by weight, of at least one photoinitiator PI, and d) 0.05 - 5% by weight, preferably 0.25 - 3.5% by weight, of at least one crosslinking agent CA, all proportions being based on the total weight of the adhesive composition.

6. The radiation-curable adhesive composition according to any one of the preceding claims, wherein the at least one styrene-based polymer SP is selected from styrene-isoprene-styrene (SIS) block copolymers, styrene-butadiene-styrene (SBS) block copolymers, styrene-isoprene-butadiene-styrene block copolymers (SIBS), and styrene-butadiene rubber (SBR).

7. The radiation-curable adhesive composition according to any one of the preceding claims, wherein the at least one styrene-based polymer SP comprises at least one styrene-isoprene-styrene block copolymer SP1 and / or at least one styrene-butadiene-styrene block copolymer SP2.

8. A radiation-curable adhesive composition according to any one of the preceding claims, wherein the at least one tackifying resin TR has a softening point measured by the ring and ball method according to the standard DIN EN 1238:2011 of 65 - 185 °C, preferably 75 - 175 °C and / or a number average molecular weight (Mn) of 150 - 5000 g / mol, preferably 250 - 3500 g / mol determined by gel permeation chromatography using polystyrene as a standard sample.

9. A radiation-curable adhesive composition according to any one of the preceding claims, further comprising: e) at least one plasticizer PL, preferably selected from processing oils and liquid polyolefin resins.

10. A radiation-curable adhesive composition according to any one of the preceding claims, further comprising: f) at least one liquid rubber LR.

11. An at least partially cured adhesive obtained by subjecting a substance of a radiation-curable adhesive composition according to any one of the preceding claims to radiation having a wavelength in the range of 365 - 500 nm, preferably 365 - 475 nm.

12. A method for preparing an at least partially cured adhesive, comprising the steps of: i. providing a substance of a radiation-curable adhesive composition according to any one of claims 1 - 10, and ii. subjecting the substance to radiation having a wavelength in the range of 365 - 500 nm, preferably 365 - 475 nm, to initiate a curing reaction of the radiation-curable adhesive composition.

13. A vibration and noise damping element (1), comprising: i) a damping layer (2) having a first surface (3) and a second surface (3'), and ii) an adhesive layer (4) composed of the at least partially cured adhesive according to claim 11 and covering at least a part of the first surface (3) of the damping layer (2), wherein the damping layer (2) contains or consists of a sound damping material, and the sound damping material comprises: - an asphalt component BC or a polymer component PC, - at least one hydrocarbon resin HR, - optionally, at least one wax W, - optionally, at least one plasticizer PL, and - at least 25 wt%, preferably at least 35 wt% of at least one solid particle filler F based on the total weight of the sound damping material.

14. Element (1) according to claim 13, wherein the damping layer (2) has a maximum thickness of 0.5 - 15 mm, preferably 1 - 10 mm and / or a mass per unit area of 1 - 5 kg / m 2 , preferably 1 - 4.5 kg / m 2 ².

15. A method for preparing a vibration and noise damping element according to claim 13 or 14, the method comprising the steps of: I. providing the damping layer (2) defined in claim 13, II. providing a film of a radiation-curable adhesive composition according to any one of claims 1 - 10 on the first surface (3) of the damping layer (2), III. subjecting the adhesive film to radiation having a wavelength in the range of 365 - 500 nm, preferably 365 - 475 nm, to effect at least partial curing of the radiation-curable adhesive composition, and IV. optionally, cutting the element obtained from step (iii) into a predetermined size, such as length and / or width.

16. A method for providing a damping system, comprising the steps of: I) providing a vibration and noise damping element (1) according to claim 13 or 14, and II) Bring the outer major surface of the adhesive layer (4) into contact with the noise-emitting surface (7) of the substrate (6), and apply sufficient pressure to form an adhesive bond between the first surface (3) of the damping layer (2) and the noise-emitting surface (7).

17. A damping system, comprising a substrate (6) having a noise-emitting surface (7) and a vibration and noise damping element (1) according to claim 13 or 14, wherein at least a portion of the first surface (3) of the damping layer (2) is adhesively bonded to the noise-emitting surface (7) via the adhesive layer (4), and wherein the substrate (6) having the noise-emitting surface (7) is preferably part of the structure of a motor vehicle or white goods.

Images