WO2018149720A1

WO2018149720A1 - Vibration-damping silicone adhesive compound

Info

Publication number: WO2018149720A1
Application number: PCT/EP2018/053145
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: KR20190103331A; DE102017202624A1; TW201835280A; EP3583185A1; TWI669366B; CN110225951A

Abstract

The invention aims to provide an easy-to-use adhesive compound with good vibration-damping properties which are available and adjustable across a broad range of temperatures, said adhesive compound additionally having sufficient mechanical stability even at high temperatures. This is achieved using a composition for producing an adhesive compound which comprises a) at least one silicone that contains at least two alkenyl groups; b) at least one silicone resin; and c) at least one radical former that contains at least one peroxide functional group. The invention also relates to an adhesive compound that can be obtained by thermally cross-linking a composition according to the invention.

Description

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. Object of the present invention is to provide an easily applicable adhesive with good vibration damping properties available that are adjustable and available over a wide temperature range, the adhesive also has sufficient mechanical stability, especially at elevated temperatures.

The solution to the problem is based on the idea to use an unconventionally crosslinked, based on alkenyl-containing silicone pressure-sensitive adhesive. A first, more general The invention relates to a composition for producing a pressure-sensitive adhesive which

a) at least one silicone containing at least two alkenyl groups;

b) at least one silicone resin;

c) at least one free-radical generator containing at least one peroxide function contains.

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 obtain 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. From the composition according to the invention it is possible-largely by removal of the solvent and crosslinking of the composition-to prepare pressure-sensitive adhesives which have very good damping properties over a wide temperature range and which can be adjusted in a targeted manner. At the same time, the pressure-sensitive adhesives show good mechanical stability at high temperatures, in particular at temperatures of up to 170 ° C. Both the temperature at which the maximum of the damping effect is achieved, and the strength of the damping effect itself can be adjusted. Compositions according to the invention or pressure-sensitive adhesives prepared therefrom can therefore advantageously be used wherever damping, in particular acoustic damping, must be effected even at high temperatures. They are particularly well suited for bonding foils for loudspeaker membranes and for gluing components of brake systems. Another object of the invention is a pressure-sensitive adhesive which is obtainable by thermal crosslinking of a composition according to the invention.

The composition according to the invention contains as component a) at least one silicone. A silicone according to the invention is preferably a) a polymer based on siloxane 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 represent alkyl, aryl, or alkenyl Polydiorganosiloxy- and 0 to 10% , based on the number of all radicals R, stand for OH groups and n, m> 0 and o, p> 0 applies. According to the invention, at least two alkenyl groups are contained, ie at least two radicals R each represent an alkenyl group. The formula (1) is not a structural formula and so far only the composition of the silicone from the siloxane units, but not their relationship to each other again.

The silicone is preferably a) a linear polymer according to the general formula (2)

(2) R'3Si-O- (SiR'2-0) _m -SiR'3, wherein the radicals R 'independently of one another are alkyl, phenyl or alkenyl radicals and 0 to 10%, based on the number of radicals R', of OH groups, where 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 polydimethylsiloxane, a poly (methylphenyl) siloxane or a dimethylsiloxane-diphenylsiloxane copolymer. In particular, the silicone 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 silicone of component a) contains at least two alkenyl groups. Via the alkenyl groups it is usually possible to crosslink such silicones by adding Si-H groups of a crosslinker substance to the alkenyl groups of the silicone macromolecules. A key finding of the present invention is that crosslinking of such - in fact addition-crosslinkable - silicones is also possible via radicals obtainable from peroxides and leads to pressure-sensitive adhesives having very good damping properties. The composition according to the invention is therefore preferably free of substances which contain one or more Si-H groups. Preferably, the alkenyl groups of the silicone contain 2-10 C atoms. The alkenyl groups of the silicone 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. Most preferably, the alkenyl groups of the silicone include vinyl groups. In particular, the alkenyl groups of the silicone are vinyl groups. The weight-average molar mass Mw of the at least one silicone a) is preferably 31,000-2,000,000 g / mol, more preferably 45,000-1,000,000 g / mol.

Silicones a) are contained in the composition according to the invention preferably to a total of 10 to 90 wt .-%, based on the solids content of the composition. It may contain a silicone a) or a mixture of different silicones a). Silicones 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 45 to 75 wt .-%, each based on the solids content of the composition.

In addition to the silicone (s) a), further silicones which contain no alkenyl groups may be present in the composition according to the invention. These may be, for example, pure polydimethylsiloxanes. The composition according to the invention contains at least one silicone resin as component b). The at least one silicone resin b) 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 b) to be present in the composition, in particular mixtures of the abovementioned silicone resins. Particularly preferably, the at least one silicone resin b) 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 b) is preferably 500 - <30,000 g / mol. The resin may contain alkenyl groups. Suitable silicone resins are e.g. 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 Silmer VQ9XYL and Silmer Q9XYL from Siltech.

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 according to the invention reaches its maximum value (T _ta n δ max), wherein T _ta n δ max is adjusted 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% by weight, based on the total amount of silicone and silicone resins of the composition The process according to the invention makes it possible to match the silicone PSA obtainable from the composition to the temperature range expected for the intended use Furthermore, it becomes possible to easily adapt a previously prepared basic formulation to one by adding an appropriate amount of silicone resin b) expected temperature "to cut".

Preferably, the proportion of the totality of all silicone resins b) to the total of all silicones a) and all silicone resins b) is at most 90% by weight. In one embodiment of the invention, the proportion of the total of all silicone resins b) to the total of all silicones a) and all silicone resins b) is at least 30 wt .-%, preferably at least 45 wt .-%, in particular 45 to 70 wt .-%.

The composition according to the invention is preferably free of substances suitable for crosslinking of alkenyl-containing silicones which contain at least two reactive Si-H groups (Si-H crosslinkers). By "reactive Si-H groups" is meant Si-H groups which can add to a C =C double bond of a silicone a) and / or a resin b) of the composition according to the invention irrelevant. The composition of the invention is preferably free of substances suitable for accelerating a reaction of Si-H- with the alkenyl groups. Suitable substances for accelerating a reaction of the Si-H- with the alkenyl groups are, in particular, platinum or platinum compounds, such as, for example, the Karstedt catalyst (a Pt (0) complex compound), or rhodium compounds.

The composition according to the invention contains at least one radical generator which contains at least one peroxide function. A "free-radical generator" is understood as meaning a compound which decomposes thermally or photochemically into free radicals and thereby initiates free-radical reactions The radical generator is preferably 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-butylcumyl 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.

Free-radical generators which contain at least one peroxide function are preferably in the composition according to the invention to a total of 0.3 to 3 wt .-%, particularly preferably to a total of 0.5 to 2 wt .-%, each based on the solids content of the composition, contain.

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 components listed hitherto, further constituents in the composition according to the invention may be used in the sense of auxiliaries and adjuvants, for example anchoring aids; organic and / or inorganic pigments; Fillers such as carbon black, graphite or carbon nanotubes and organic and / or inorganic particles (eg polymethyl methacrylate (PMMA), barium sulfate or titanium oxide (ΤΊ02)) 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 silicone (s) (base polymer (s)) and silicone resin (s).

In a further embodiment, the composition according to the invention is free from any constituents which exceed components a) to c) and one or more solvents.

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 here the maximum achievable under the present, in particular from the composition of the composition and the resulting theoretically available sites of linkage, otherwise corresponding to the conditions usual for the crosslinking of silicone adhesives, conditions networking under the influence of heat Preferably, the maximum value of the quotient of loss modulus (G ") and storage modulus (G ') (tan δ, measured at 10 rad / s) of the pressure-sensitive adhesive of the invention in the temperature range between -60 ° C and 170 ° C is at least 0.6; in particular, it is at least 0.8. With these values, good - in particular acoustic - damping properties are obtained.

Also preferably, the temperature range within the range of - 60 ° C to 170 ° C, in which the tan δ of the respective PSA is at least 0.5, at least 45 K, more preferably at least 50 K, in particular at least 70 K. Further comprises preferably the temperature range within the range of - 60 ° C to 170 ° C, in which the tan δ of the respective PSA is at least 0.7, at least 15 K, more preferably at least 30 K, in particular at least 40 K. Compositions according to the invention or pressure-sensitive adhesives obtainable therefrom can advantageously be used for bonding acoustic membranes, for example loudspeaker membranes in mobile telephones, laptops, televisions and other devices equipped with loudspeakers, and for bonding brake system components in motor vehicles. 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 squeak 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

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

- steel strength:

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 for 5 minutes in the air, so that the solvent could 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 holder that allowed the pattern to become one Peel angle 90 ° vertically upwards. The bond strength was measured with Zwick tensile testing machine.

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

compositions

Used chemicals:

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

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

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

Perkadox® 33 - dibenzoyl peroxide, 33% mixture with inert filler,

powder

Syl-Off® 7678 - 100% Si-H crosslinker

Syl-Off® 4000 - 100% platinum catalyst preparation

General instructions for the formulation of a composition according to the invention or for the preparation of pressure-sensitive adhesives from these:

50 g of DC 7651 were admixed with 19.57 g of DC 7066 and 1.09 g of Perkadox 33 in 5 ml of toluene. The mixture was then homogenized for 2 h with the magnetic stirrer.

The resulting mixture was applied to a fluorosilicone PET liner in the form of a layer of 50 g / m ² (for bond strength measurements) and 500 g / m ² (for Dynamic Mechanical Analysis), followed by 2 min at 90 ° C Crosslinked at 170 ° C for 5 min.

Table 1 lists the formulations used. Table 1: Compositions for the production of pressure-sensitive adhesives

Comparative example

= Pressure-sensitive adhesive

Of the pressure-sensitive adhesives obtained from compositions 1 to 3, the bond strength to steel and the values of tan δ in the temperature range from -60 ° C. to 165 ° C. were determined at 15 K intervals. The respective results are included in Table 2.

Table 2: Results

Claims

claims

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

a) at least one silicone containing at least two alkenyl groups;

b) at least one silicone resin;

c) at least one free radical generator containing at least one peroxide function.

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

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

4. Composition according to one of the preceding claims, characterized in that the proportion of the totality of all silicone resins b) to the total of all silicones a) and all silicone resins b) is at most 90 wt .-%.

5. Composition according to one of the preceding claims, characterized in that the proportion of the totality of all silicone resins b) to the totality of all silicones a) and all silicone resins b) is at least 30 wt .-%.

6. Composition according to one of the preceding claims, characterized in that the silicone resin is an MQ resin.

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

A pressure-sensitive adhesive composition obtainable by thermal crosslinking of a composition according to any one of the preceding claims.

9. PSA according to claim 8, 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 0.6.

10. pressure-sensitive adhesive composition according to one of claims 8 and 9, 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 45 K.

1 1. Method for setting the temperature at which the quotient of loss modulus (G ") and storage modulus (G ') of a pressure-sensitive adhesive according to one of Claims 8 to 10 reaches its maximum value (Ttan ö max),

wherein Ttan δ max is adjusted by changing the silicone resin concentration with otherwise constant proportions.

12. A process for producing a pressure-sensitive adhesive, which comprises the thermal crosslinking of a composition according to one of claims 1 to 7.

13. Multilayer composite comprising

two films whose major component 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, polyarylate, polyetheretherketone and polyaryletherketone; and

a pressure-sensitive adhesive according to any one of claims 8 to 10,

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