WO2018149719A1

WO2018149719A1 - Vibration-damping silicone adhesive compound

Info

Publication number: WO2018149719A1
Application number: PCT/EP2018/053144
Authority: WO
Inventors: Nikolay BELOV; Tobias Winkler; Gero Maatz
Original assignee: Tesa Se
Priority date: 2017-02-17
Filing date: 2018-02-08
Publication date: 2018-08-23
Also published as: KR20190101462A; DE102017202623A1; TW201833288A; EP3583184A1; TWI675897B; KR102284815B1; CN110249018A

Abstract

The invention aims to provide an easy-to-use adhesive compound with good vibration-damping properties which are available across a broad range of temperatures. This is achieved using a composition for producing an adhesive compound, containing: a) at least one organopolysiloxane that comprises multiple Si-bonded alkyl groups, and contains at least two Si-bonded alkenyl groups; b) at least one organopolysiloxane which comprises multiple Si-bonded aryl groups and contains at least two radically cross-linkable substituents; and c) at least one radical former. The invention also relates to an adhesive compound that can be obtained by thermally cross-linking a composition according to the invention.

Description

tesa SE

Norderstedt

Vibration-damping silicone pressure-sensitive adhesive

The present invention relates to the technical field of pressure-sensitive adhesives, as they are widely used in the art for temporary or permanent bonding of materials and parts to be joined. In particular, the invention relates to silicone-based PSAs, which are characterized by good vibration damping properties.

Damping is generally understood to mean the transfer of mechanical energy into so-called lost heat. The acoustic damping is about the irreversible conversion of sound energy into heat. Acoustic damping - or synonymously sound damping or sound absorption - can occur in gaseous, liquid and solid bodies.

The generation of sound in mobile phones and smartphones for the reproduction of speech, ringtones, music, etc. is done by small electro-acoustic transducers, so-called micro-speakers. The size of the membranes of such microspeakers, which are also used in headphones, notebooks, LCD TVs or personal digital assistants (PDAs), is typically in the range of 20 mm ² to 900 mm ² .

As microspeakers become smaller and flatter as a result of the design requirements for the corresponding electronic devices, but are additionally operated at a higher power, the temperature load on the microspeaker, and in particular its diaphragm, increases more and more. The membrane must therefore be made of a material that has a long life and does not crack even at high temperatures and high mechanical loads. At the same time, the membrane material should also have good acoustic properties to give the speaker a good sound quality.

The general requirements for the material of a loudspeaker diaphragm are on the one hand high rigidity and low density for generating a high sound pressure and the coverage of a wide frequency range. On the other hand, the material should at the same time have a high internal damping in order to achieve a smooth frequency response worry and minimize distortion. Since the stiffness, light and well-damped properties give a constructive contradiction and can not all be fulfilled simultaneously (the stiffer, the lower the damping and vice versa), compromises in terms of rigidity and damping of the membrane material must generally be made or more rigid for each membrane Materials combined with good damping materials.

US Pat. No. 7,726,441 B2 describes a membrane composed of a multilayer composite of two rigid polymer films and a damping adhesive layer lying between these films.

The publications DE 10 2007 030 665 A1 and US Pat. No. 8,141,676 B2 each describe a five-layer composite in which two outer layers and one middle layer are separated from one another by a thermoplastic adhesive or an acrylic adhesive. In such multilayer membranes, the same adhesives are used in the same thicknesses for the two adhesive layers. This is due to the fact that the membrane in the speaker should oscillate as symmetrically and uniformly as possible and an asymmetrical structure with respect to the damping adhesive layers can easily lead to distortions; whereby the generated sound quality would be reduced. Furthermore, the acoustic properties of a loudspeaker can be very dependent on which side of the membrane of asymmetrical construction is attached to the coil. Therefore, symmetric membranes have prevailed in the use of loudspeakers, to avoid that there is a quality deviations due to incorrect installation of the membrane.

In general, it can be stated that adhesives are used in the prior art as vibration-damping material, for example in the abovementioned combinations of rigid materials with good damping properties. US 5,464,659 describes a method of vibration damping an article which provides for the application of a vibration damping material of 5 to 95% acrylic monomer (s) and 95 to 5% silicone adhesive on the article, the sum of the two components being 100%. The use of adhesives, in particular silicone-based adhesives, as a vibration-damping component is not limited to loudspeaker membranes. For example, US 2014/0017491 A1 describes a silicone adhesive composition which, before curing, comprises a silicone elastomer, a silicone resin, a reaction product of a silicone elastomer and a silicone resin, a silicone hydride crosslinker and a platinum catalyst. A resulting adhesive is used in a transfer tape for connecting brake components, for example for connecting the brake disc and brake pad. EP 1 018 725 A2 describes a method for deadening a sheet metal part, for example a vehicle body part, by producing a screwed, riveted or welded connection of a metal sheet with the sheet metal part to be deconvolved with the interposition of an adhesive layer. As adhesive layer for use in sheet metal parts in the temperature range between -20 ° C and +50 ° C while a polyacrylic acid ester copolymer and for use at higher temperatures in the range of 0 ° C to 100 ° C, a crosslinked silicone adhesive is used. Through the screw, rivet or welded connection, the energy of the oscillating sheet metal part is conducted to a high degree in the sandwich of at least one adhesive layer and at least one metal sheet, so that the sandwich is able to convert a high vibrational energy fraction into heat.

EP 1 035 345 A2 describes a damping plate for attachment to a carrier plate of a brake shoe of a disc brake which has a self-adhesive damping layer on the inner side facing the brake shoe.

There is a continuing need for versatile adhesives with good vibration damping properties. The object of the present invention is to provide an easily applicable pressure-sensitive adhesive with good vibration-damping properties which are available over a wide temperature range.

The object of the invention is based on the idea to use a blend of silicone pressure-sensitive adhesives with partly atypical crosslinking chemistry. A first, general subject of the invention is a composition for producing a pressure-sensitive adhesive which a) at least one organopolysiloxane containing several Si-bonded alkyl groups, containing at least two Si-bonded alkenyl groups;

b) at least one organopolysiloxane containing a plurality of Si-bonded aryl groups, containing at least two free-radically crosslinkable

substituent; and

c) contains at least one radical generator.

Under a PSA or synonymous a pressure sensitive adhesive according to the invention, as common in common usage, a substance understood that - especially at room temperature - permanently sticky and sticky. A characteristic of a pressure-sensitive adhesive is that it can be applied by pressure to a substrate and adhere there, whereby the pressure to be applied and the duration of this pressure are generally not specified. In some cases, depending on the precise nature of the pressure-sensitive adhesive, the temperature and humidity, as well as the substrate, the action will be a short-term minimum pressure that does not exceed a light touch for a brief moment to achieve the adhesion effect. In other cases, a long-term exposure time of high pressure may be necessary. Pressure-sensitive adhesives have special, characteristic viscoelastic properties which lead to permanent tackiness and adhesiveness. Characteristic of them is that when they are mechanically deformed, it comes both to viscous flow processes as well as to build elastic restoring forces. Both processes are in a certain ratio with regard to their respective proportions, depending on the exact composition, the structure and the degree of crosslinking of the pressure-sensitive adhesive as well as on the speed and duration of the deformation and on the temperature.

The proportional viscous flow is necessary to achieve adhesion. The viscous components, caused by macromolecules with relatively high mobility, allow good wetting and a good flow onto the substrate to be bonded. A high proportion of viscous flow leads to a high pressure tack (also referred to as tack or surface tackiness) and thus often also to a high bond strength. Strongly crosslinked systems, crystalline or glassy solidified polymers are usually not or at least only slightly tacky due to the lack of flowable components. The proportional elastic restoring forces are necessary to achieve cohesion. They are caused for example by very long-chained and strongly entangled as well as by physically or chemically crosslinked macromolecules and allow the transmission of forces acting on an adhesive bond forces. They result in an adhesive bond being able to withstand a sustained load acting on it, for example in the form of a permanent shearing load, to a sufficient extent over a relatively long period of time.

For a more detailed description and quantification of the degree of elastic and viscous component as well as the ratio of the components to one another, the variables storage modulus (G ') and loss modulus (G ") which can be determined by means of dynamic mechanical analysis (DMA) can be used elastic proportion, G "is a measure of the viscous portion of a substance. Both quantities depend on the deformation frequency and the temperature.

The sizes can be determined with the help of a rheometer. The material to be examined is exposed to a sinusoidal oscillating shear stress in a plate-and-plate arrangement, for example. In shear stress controlled devices, the deformation as a function of time and the time lag of this deformation are compared with the introduction of the shear stress measured. This time offset is referred to as the phase angle δ.

The storage modulus G 'is defined as follows: G' = (τ / γ) ^« cos (ö) (τ = shear stress, γ = deformation, δ = phase angle = phase shift between shear stress and deformation vector). The definition of the loss modulus G "is: G" = (τ / γ) ^" sin (5) (T = shear stress, γ = deformation, δ = phase angle = phase shift between shear stress vector and deformation vector).

A substance is generally considered to be pressure sensitive and is defined as tacky if, at room temperature, here by definition at 23 ° C, in the deformation frequency range of 10 ° to 10 ¹ rad / sec G 'at least partially in the range of 10 ³ to 10 ⁷ Pa and if G "is also at least partially within this range." Partially "means that at least a portion of the G 'curve lies within the window defined by the deformation frequency range of 10 ° to 10 inclusive ¹ rad / sec (abscissa) and the range of G 'values of from 10 ³ to 10 ⁷ Pa inclusive (ordinate) is spanned. For G "this applies accordingly. The composition according to the invention can be used-essentially by removing the solvent and crosslinking the composition-to prepare pressure-sensitive adhesives which have very good damping properties, in particular acoustic, over a wide temperature range. Thus, compositions according to the invention or pressure-sensitive adhesives prepared therefrom can advantageously be used wherever damping must be effected even at high and / or varying temperatures. They are particularly well suited for bonding foils for loudspeaker membranes and for gluing components of brake systems.

The composition of the invention contains as component a) at least one organopolysiloxane, as it is generally referred to as silicone. An organopolysiloxane according to the invention is preferably a) a polymer having a composition of the organosiloxane units according to the general formula (1)

(1) (R ₃ SIOI / 2) n (R 2 SiO) _m (RSi0 _3/2) o (Si02) p, in which the radicals R independently of one another principle for alkyl, phenyl, Polydiorganosiloxy- or alkenyl radicals, and from 0 to 1 0%, based on the number of all radicals R, are OH groups and n, m> 0 and o, p> 0 applies, wherein the polymer contains at least two Si-bonded alkyl groups and at least two alkenyl groups. Formula (1) is not a structural formula and thus only reflects the composition of the organopolysiloxane from the organosiloxane units, but not their relationship to one another.

The organopolysiloxane is preferably a) a linear polymer of the general formula (2) (2) R'3Si-O- (R'2Si-O) m-SiR'3, in which the radicals R 'are each independently alkyl, phenyl - or alkenyl radicals and to 0 to 1 0%, based on the number of all radicals R ', are OH groups, where at least two radicals R' are alkyl groups and at least two radicals R 'are alkenyl groups; and m stands for a natural number of 2,000 to 6,000. In principle, the radicals R 'can be distributed over the linear silicone in all conceivable and chemically possible constellations. For example, polydimethylsiloxanes, poly (methylphenyl) siloxanes and

Poly (dimethylsiloxane / diphenylsiloxane) copolymers. If the alkenyl groups are not (only) terminally but (also) arranged within the polymer chains of the aforementioned silicones, they are not pure polydimethylsiloxanes, poly (methylphenyl) siloxanes, poly (dimethylsiloxane / diphenylsiloxane) copolymers, etc. According to the invention these are Silicones - according to the expert's practice - nevertheless as mentioned above.

Preferably, the radicals R 'in the general formula (2) independently of one another represent methyl, ethyl, phenyl or alkenyl radicals, where at least two radicals R' are alkenyl radicals. The silicone is particularly preferably a) a polydimethylsiloxane, a poly (methylphenyl) siloxane or a dimethylsiloxane-diphenylsiloxane copolymer. In particular, the organopolysiloxane of component a) is a polydimethylsiloxane. The formula (2) is a structural formula, so also the linkage of the siloxane units with each other again.

The at least one organopolysiloxane of component a) contains at least two alkenyl groups. Crosslinking is usually enabled via the alkenyl groups in such silicones by adding to the composition another organopolysiloxane containing several Si-H groups. It then comes to an addition of the Si-H functions to the alkenyl groups and in this way to build a crosslinked silicone. The alkenyl groups of the silicone a) preferably contain 2-10 C atoms. The alkenyl groups of the organopolysiloxane of component a) are particularly preferably selected independently of one another from the group consisting of vinyl, propenyl, allyl, butenyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl and decenyl groups. These groups are particularly reactive and thus enable efficient networking. Most preferably, the alkenyl groups of the organopolysiloxane of component a) comprise vinyl groups. In particular, the alkenyl groups of the organopolysiloxane of component a) are vinyl groups.

It is a peculiarity of the present invention that the composition of the invention is designed so that the organopolysiloxane of component a) is not crosslinked as usual via a compound containing Si-H groups, but instead untypical of a radical mechanism. Component a) is evidently included in the crosslinking of component b) designed from the outset for radical crosslinking. The composition according to the invention is therefore preferably free of substances which contain one or more Si-H groups.

It has been found that a composition of the invention which is atypically crosslinked in the above sense leads to a considerable broadening of the temperature range in which good vibration damping occurs. This manifests itself in relation to conventional silicone compositions greatly widened, obtained from the plot of the tan δ against the temperature curves above a value of tan δ = 0.5 and 0.8. Preferably, the composition of the invention is free of substances containing one or more Si-H groups.

The weight-average molar mass Mw of the organopolysiloxane of component a) is preferably 31,000-2,000,000 g / mol, more preferably 45,000-1,000,000 g / mol.

One or more organopolysiloxanes of component a) are preferably contained in the composition according to the invention to a total of 10 to 90 wt .-%, based on the solids content of the composition. It is thus possible for an organopolysiloxane of component a) or a mixture of different organopolysiloxanes of component a) to be present. Organopolysiloxanes of component a) are more preferably contained in the composition according to the invention to a total of 20 to 80 wt .-%, in particular to a total of 30 to 60 wt .-%, each based on the solids content of the composition.

The composition according to the invention contains as component b) at least one organopolysiloxane having several Si-bonded aryl groups and containing at least two free-radically crosslinkable substituents. Preference is given to an organopolysiloxane according to the invention b) a polymer having a composition of the organosiloxane units of the general formula (3)

(3) (R _"3 SIOI / 2) _q (R '2 SiO) _r (R" SI03 / 2) s (Si0 ₂₎ t in which the radicals R "independently of one another alkyl, aryl or Polydiorganosiloxy radicals and to 0 to 10%, based on the number of all radicals R ", are OH groups, wherein the polymer contains at least two methyl groups and q, r> 0 and s, t> 0 applies. According to the invention, a plurality of Si-bonded aryl groups are contained. At least the methyl groups are free-radically crosslinkable substituents in the polymer according to the formula (3). The formula (3) is not a structural formula and insofar only represents the composition of the organopolysiloxane from the organosiloxane units, but not their relationship to each other again.

The organopolysiloxane b) is preferably a linear polymer of the general formula (4)

(4) R '"3Si-O- (R'" 2Si-O) rSiR '"3, wherein the radicals R'" independently of one another are alkyl or aryl radicals and a maximum of 10%, based on the number of all radicals R "\ represent OH groups, where at least two radicals R '" represent methyl groups and at least two radicals R' "represent aryl groups, and in which r is a natural number of 2,000 to 6,000 conceivable and chemically possible constellations distributed over the linear silicone. For example, polydiphenylsiloxanes, poly (methylphenyl) siloxanes and poly (dimethylsiloxane / diphenylsiloxane) copolymers are known.

The radicals R '' in the general formula (4) are preferably, independently of one another, methyl, ethyl or phenyl radicals or OH groups, where at least two radicals R '' 'represent phenyl groups and at least two radicals R' '' represent methyl groups The Si-bonded aryl groups of the organopolysiloxane of component b) are particularly preferably phenyl groups, silicone b) being most preferably a polydiphenylsiloxane, a poly (methylphenyl) siloxane or a dimethylsiloxane-diphenylsiloxane copolymer, in particular the organopolysiloxane is Component b) a poly (methylphenyl) siloxane or a dimethylsiloxane-diphenylsiloxane copolymer The formula (4) is a structural formula, ie it also represents the linkage of the siloxane units with one another.

The at least one organopolysiloxane of component b) contains at least two free-radically crosslinkable substituents. Such groups usually allow cross-linking via these groups by adding a free-radical generator to the composition. It then comes to the formation of radicals that cause the construction of a crosslinked silicone by recombination. Preferred are the Radically crosslinkable substituents of the organopolysiloxane of component b) methyl groups.

The organopolysiloxane of component b) is preferably free of Si-bonded alkenyl groups, more preferably free of any alkenyl groups.

The weight-average molar mass Mw of the organopolysiloxane of component b) is preferably 31,000-1,500,000 g / mol, more preferably 45,000-1,200,000 g / mol, in particular 50,000-1,000,000 g / mol.

One or more organopolysiloxanes of component b) are preferably present in the composition according to the invention to a total of 10 to 90 wt .-%, based on the solids content of the composition. It is therefore possible for an organopolysiloxane of component b) or a mixture of different organopolysiloxanes of component b) to be present. Organopolysiloxanes of component b) are more preferably contained in the composition according to the invention to a total of 20 to 80 wt .-%, in particular to a total of 40 to 70 wt .-%, each based on the solids content of the composition.

The weight ratio of the organopolysiloxanes of component a) to the organopolysiloxanes of component b) of the composition according to the invention is preferably from 1: 4 to 3: 1, more preferably from 1: 3 to 7: 3, in particular from 3: 7 to 3: 2.

In addition to the silicones of components a) and b), further silicones may be present in the composition according to the invention which contain neither alkenyl nor aryl groups nor OH groups. These may be, for example, pure polydimethylsiloxanes.

The composition according to the invention contains at least one radical generator. This is understood to mean a compound which decomposes thermally or photochemically into free radicals and thereby starts radical reactions. The radical generator is preferably a peroxide. In particular, the radical generator is selected from the group consisting of di (4-methylbenzoyl) peroxide, dibenzoyl peroxide, di (2,4-dichlorobenzoyl) peroxide, dicumyl peroxide, di- (4-tert-butylcyclohexyl) peroxydicarbonate, dilauroyl peroxide, Dicetyl peroxydicarbonate, tert-butyl peroxybenzoate, tert-butyl cumyl peroxide, di-tert-butyl peroxide, di- (tert-butylperoxyisopropyl) benzene, 2,5-dimethyl-2,5-di (tert-butylperoxy) hexyn-3 and 3,3,5 , 7,7-pentamethyl-1,2,4-trioxepane. Radical formers are in the composition according to the invention preferably to a total of 0.3 to 6 wt .-%, more preferably to a total of 0.5 to 4 wt .-%, in particular to a total of 1 to 3 wt .-%, each based on the solids content of Composition, included. The composition of the invention preferably contains at least one silicone resin. The silicone resin is preferably selected from MQ, MTQ, TQ, MT and MDT resins. According to the invention, it is also possible for mixtures of different silicone resins to be present in the composition, in particular mixtures of the abovementioned silicone resins. Most preferably, the silicone resin is an MQ resin. MQ silicone resins are readily available and are characterized by very good stability. If a plurality of silicone resins are present in the composition according to the invention, all silicone resins of the composition according to the invention are very particularly preferably MQ resins.

The weight-average molar mass Mw of the at least one silicone resin is preferably 500 - <30,000 g / mol. The resin may contain alkenyl groups. Suitable silicone resins are, for example, DC 2-7066 from Dow Corning; MQ Resin VSR6201 from Chenguang Fluoro & Silicone Elastomers Co., Ltd .; MQ-RESIN POWDER 803 TF from Wacker Silicones; SR 545 from Momentive Performance Materials or SilmerVQ9XYL and Silmer Q9XYL from Siltech. Preferably, the proportion of the totality of all silicone resins in the totality of all silicones a) and b) and of all silicone resins is at most 90% by weight. In one embodiment of the invention, the proportion of the totality of all silicone resins in the totality of all silicones a) and b) and of all silicone resins is at least 30% by weight. In a further embodiment of the invention, the proportion of the totality of all silicone resins in the entirety of all silicones a) and b) and of all silicone resins is at least 45% by weight. In particular, silicone resins are included in total 30 to 80 wt .-%, based on the total weight of all organopolysiloxanes and all silicone resins of the composition in the composition of the invention. The composition according to the invention preferably contains at least one solvent. The solvent is preferably selected from aromatic and aliphatic hydrocarbons, in particular from toluene, xylene and gasoline, from aprotic carbonyl compounds, in particular from ketones, esters and ethers and from inert protic solvents, in particular isopropanol.

In addition to the base polymer (s), the silicone resin (s) and the other ingredients listed heretofore, the composition according to the invention may contain further constituents in the sense of auxiliaries and adjuvants, e.g. Anchorage aids; organic and / or inorganic pigments; Fillers such as carbon black, graphite or carbon nanotubes and organic and / or inorganic particles (e.g., polymethyl methacrylate (PMMA), barium sulfate or titanium oxide (.02)) may be included.

In one embodiment of the invention, the composition of the invention independently contains 0.1 to 5 parts by weight of one or more anchoring aids and / or one or more pigments and / or 0.1 to 50 parts by weight of one or more fillers, each based on 100 parts by weight of the total on base polymer (s) and silicone resin (s). In a further embodiment, the composition according to the invention is free of any constituents which go beyond the previously mentioned components.

Another object of the invention is a process for the preparation of a pressure-sensitive adhesive composition comprising the thermal crosslinking of a composition according to the invention.

Another object of the invention is a pressure-sensitive adhesive which is obtainable by thermal crosslinking of a composition according to the invention. By "thermal crosslinking" is meant here the crosslinking under the influence of heat that is obtainable under the respective present, in particular from the composition of the composition and the resulting theoretically available attachment sites, otherwise corresponding to the conditions usual for the crosslinking of silicone adhesive compositions , The temperature at which the quotient of loss modulus (G ") and storage modulus (G ') (tan δ) of the pressure-sensitive adhesive of the invention reaches its maximum value can be adjusted by varying the resin content Temperature at which the quotient of loss modulus (G ") and storage modulus (G ') (tan δ) of a pressure-sensitive adhesive obtainable by thermal crosslinking of a composition containing at least one silicone resin according to the invention reaches its maximum value ( _Ta n 5 max), where T _ta n 5 max is set by changing the silicone resin concentration with otherwise constant proportions.

In general, an increase in the silicone resin concentration causes a shift of the tan δ maximum to higher temperatures. In the case where several silicone resins are present in the composition according to the invention, the term "silicone resin concentration" is understood to mean, of course, the total concentration of silicone resins 80 wt .-%, more preferably from 20 to 50 wt .-%, each based on the total amount of silicones and silicone resins of the composition.

The latter method according to the invention makes it possible to adjust the silicone PSA obtainable from the composition to the temperature range expected for the intended use. Simple test series can be used to produce a mass with optimal damping properties, which are most pronounced in the tan δ maximum. Furthermore, it becomes possible to "cut" a previously prepared base formulation by adding an appropriate amount of silicone resin b) very simply to an expected temperature.

The maximum value of the quotient of loss modulus (G ") and storage modulus (G ') (tan δ max, measured at 10 rad / s) of the pressure-sensitive adhesive of the invention in the temperature range between -60 ° C. and 170 ° C. is preferably from 0.5 to 2 In particular, it is equal to or greater than 0.8, most preferably equal to or greater than 1. In this range, excellent - in particular acoustic - damping properties are obtained. Also preferably, the temperature range within the range of - 60 ° C to 170 ° C, in which tan δ of the pressure-sensitive adhesive of the invention is at least 0.5, at least 80 K, more preferably at least 150 K. Further, preferably, the temperature range within the range of - 60 ° C to 170 ° C, in which tan δ of the pressure-sensitive adhesive of the invention is at least 0.7, at least 80 K, more preferably at least 1 10 K. In particular, the temperature range within the range of - 60 ° C to 170 ° C, in the tan δ of the pressure-sensitive adhesive of the invention at least 1, 0, at least 40 K, more preferably at least 50 K. Compositions according to the invention or obtainable from pressure-sensitive adhesives can advantageously for bonding of acoustic membranes, such as speaker membranes in mobile phones, laptops, televisions and others with Equipped with loudspeakers and for gluing brake system components in Vehicles are used. For bonding loudspeaker membranes, the PSA is preferably coated in a layer thickness of 5 to 30 μηη on a film, for example by means of direct coating or lamination, and then the other film is applied to the free adhesive mass side.

Another object of the invention is a multi-layer composite, the

two films whose main component is independently selected from the group consisting of polypropylene (PP), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate (PC), polyurethane (PU), thermoplastic polyurethane (TPU), polyethylene naphthalate (PEN) , Polyphenylene sulfide (PPS), polyimide (PI), polyphenylsulfone (PPSU), polyethersulfone (PES), polysulfone (PSU), polyetherimide (PEI), polyarylate (PAR), polyetheretherketone (PEEK) and polyaryletherketone (PAEK); and a pressure-sensitive adhesive according to the invention comprises,

wherein the pressure-sensitive adhesive is disposed between these films.

Such a multilayer composite can be used particularly advantageously as an acoustic membrane in the above sense. The main component of the two films is particularly preferably a polyetheretherketone.

Further fields of application of the compositions according to the invention or the pressure-sensitive adhesives obtainable therefrom are adhesions to ceilings and floors of house and façade elements (eg doors, windows); further bonding (beyond loudspeaker membranes) in electronic devices such as mobile phones, laptops, televisions; Bonding to movable furniture elements such as drawers; Bonding of the interior lining of vehicles and aircraft; Bonding in kitchen appliances (eg mixers); Bonding of moving parts in printers; Adhesions in mass memories or drives of computers; further bonding in vehicles such as from and in oil pans, dashboards, body panels, door panels, vehicle floors, vehicle roofs, trunk lids and tailgates and vehicle windows; in particular, the noise reduction in bonnet hinges in vehicles; the noise reduction in washing machines and dryer drums; the squeal protection between window clamping rings and body of vehicles; Bonding of thick metal substrates in shipbuilding, for example, bonding of ship walls and decks; also bonding of metal plates in locomotives, train trailers and trucks; Bonding of parts in air conditioners and fans or fans; the vibration damping of optical devices and lasers as well as in sports articles such as tennis rackets. All mentioned applications aim for vibration-damping bonds.

Examples of measurement method

- Dynamic Mechanical Analysis

Device: deformation controlled rheometer (ARES), plate plate, 0 25 mm

Deformation: 1%

Frequency: 10 rad / s

Temperature sweep: see Table 2

- Kjebkraft steel:

The determination of the bond strength steel was carried out at a test climate of 23 ° C +/- 1 ° C temperature and 50% +/- 5% rel. Humidity. The tape samples were cut to 20 mm width and adhered to a steel plate. The steel plate was cleaned and conditioned before measurement. For this purpose, the plate was first wiped with acetone and then left in the air for 5 minutes to allow the solvent to evaporate.

The side of the adhesive tape pattern facing away from the test substrate was then covered with a 50 μm aluminum foil, which prevented the pattern from stretching during the measurement. After that, the test pattern was rolled up on the steel substrate. For this purpose, the adhesive tape was rolled over with a 2 kg roller 5 times back and forth at a winding speed of 10 m / min. Immediately after rolling up, the steel plate was slid into a special fixture which allowed the pattern to be withdrawn vertically at an angle of 90 °. The bond strength was measured with a Zwick tensile testing machine.

The measurement results are given in N / cm and are averaged out of three measurements.

Compositions Chemicals used:

Dow Corning® 7956 - phenyl group containing silicone + MQ resin

(Weight ratio silicone / MQ resin 9: 1 1), 59% solution in xylene

Dow Corning® 7657 polydimethylsiloxane + MQ resin (weight ratio

PDMS / MQ resin 19:31), 56% solution in xylene

Dow Corning® 7066 - MQ Silicone Resin, 62% solution in xylene

Dow Corning® 7651 vinyl group-containing polydimethylsiloxane + MQ resin

(Weight ratio PDMS / MQ resin 70:30), 46% solution in toluene

Benzoyl peroxide mixture

with dicyclohexyl phthalate - benzoyl peroxide (BPO), 50% General instructions for the formulation of a composition according to the invention or for the preparation of pressure-sensitive adhesives from these:

The stated amount (amounts see Table 1) DC 7956 was admixed with the respectively indicated amounts of DC 7657 and optionally DC 7066. The mixture was homogenized for 2 h with a magnetic stirrer. Subsequently, the indicated amount of BPO in 5 ml of toluene was added and mixed by stirring for an additional 1 hour.

The resulting mixture was applied in the form of a layer of 50 g / m ² (for measurements of bond strength) or 500 g / m ² (for dynamic mechanical analysis) on a fluorosilicone PET liner and 2 min at 90 ° C and 5 min at 170 ° C crosslinked. Table 1 lists the formulations.

Table 1: Compositions for the production of pressure-sensitive adhesives

Cf. = Comparative Example

Of the pressure-sensitive adhesives obtained from compositions 1 to 3, the bond strength to steel and the tan δ values in the temperature range from -60 ° C. to 165 ° C. were determined at 15 K intervals. From the latter, the values contained in Table 2 were obtained by applying appropriate curves against the temperature of the temperature range in which tan δ in each case at least 0.5 or at least 0.7 or 1, 0 was. Table 2: Temperature profile tan δ

from Table 1

The amounts indicated in Table 3 DC 7956 were added to the amounts listed there DC 7651, DC 2-7066 and gasoline. The mixtures were homogenized for 2 h with a magnetic stirrer. Subsequently, the indicated amounts of BPO in 5 ml of toluene were added and mixed by stirring for an additional hour.

The resulting mixtures were applied in the form of a layer of 50 g / m ² (for measurements of bond strength) or 500 g / m ² (for dynamic mechanical analysis) on a fluorosilicone PET liner and 2 min at 90 ° C and below Crosslinked at 170 ° C for 5 min.

Table 3: Compositions of PSAs

Cf. = Comparative Example

Of the pressure-sensitive adhesives obtained from compositions 4 and 5, the bond strength to steel and the tan δ values in the temperature range from -60 ° C. to 165 ° C. were determined at 15 K intervals. From the latter, the values contained in Table 4 were obtained by applying appropriate curves against the temperature of the temperature range in which tan δ in each case at least 0.5 or at least 0.7 or 1, 0 was.

Table 4: Temperature profile tan δ

Hkm = PSA, the number corresponds to the underlying composition of Table 3

Claims

claims

1 . A composition for the preparation of a pressure-sensitive adhesive composition, comprising

a) at least one organopolysiloxane containing several Si-bonded alkyl groups, containing at least two Si-bonded alkenyl groups;

b) at least one organopolysiloxane containing a plurality of Si-bonded aryl groups, containing at least two free-radically crosslinkable substituents; and

c) at least one radical generator.

2. Composition according to claim 1, characterized in that the organopolysiloxane of component a) is a polydimethylsiloxane.

3. Composition according to one of the preceding claims, characterized in that the Si-bonded alkenyl groups of the organopolysiloxane of component a) are vinyl groups.

4. Composition according to one of the preceding claims, characterized in that the Si-bonded aryl groups of the organopolysiloxane of component b) are phenyl groups.

5. Composition according to one of the preceding claims, characterized in that the weight ratio of the organopolysiloxanes of component a) to the organopolysiloxanes of component b) is from 3: 7 to 7: 3.

6. The composition according to any one of the preceding claims, characterized in that the at least one radical generator is a peroxide.

7. A composition according to any one of the preceding claims, characterized in that free radicals are contained in total to 0.5 to 2 wt .-%, based on the total weight of the composition.

8. Composition according to one of the preceding claims, characterized in that the composition contains at least one silicone resin.

9. The composition according to claim 8, characterized in that the silicone resin is an MQ resin.

10. A composition according to any one of claims 8 and 9, characterized in that silicone resins in total to 30 to 80 wt .-%, based on the total weight of all organopolysiloxanes and all silicone resins of the composition are included.

1 1. Composition according to any one of the preceding claims, characterized in that the composition contains at least one solvent.

12. Pressure-sensitive adhesive, obtainable by thermal crosslinking of a composition according to one of the preceding claims.

13. pressure-sensitive adhesive according to claim 12, characterized in that the maximum value of the quotient of loss modulus (G ") and storage modulus (G ') (tan δ) of the pressure-sensitive adhesive in the temperature range between - 60 ° C and 170 ° C is equal to or greater than 0, 8 is.

14. pressure-sensitive adhesive composition according to any one of claims 12 and 13, characterized in that the temperature range within the range of - 60 ° C to 170 ° C, in which the tan δ of the pressure-sensitive adhesive is at least 0.5, at least 80 K.

15. A process for the preparation of a pressure-sensitive adhesive, which comprises the thermal crosslinking of a composition according to one of claims 1 to 11.

16. Multilayer composite comprising

two films whose main constituent is independently selected from the group consisting of polypropylene, polyethylene terephthalate, polybutylene terephthalate, polycarbonate, polyurethane, thermoplastic polyurethane, polyethylene naphthalate, polyphenylene sulfide, polyimide, Polyphenylsulfone, polyethersulfone, polysulfone, polyetherimide, polyetheretherketone and polyaryletherketone; and

a pressure-sensitive adhesive according to any one of claims 12 to 14, wherein the pressure-sensitive adhesive is disposed between these films.