DE102022206152A1 - Brake pad with one or more adhesive layers - Google Patents

Abstract

The invention relates to a brake pad for a vehicle brake, comprising a back plate (1), a lower layer (2) and a friction material (3), which are arranged in this order along a z-direction, the brake pad being designed to, for example -Direction to be moved in order to be pressed against a rotating body for braking. The brake block further comprises one or more adhesive layers (8.1-8.6), each of the one or more adhesive layers (8.1-8.6) having a thickness in the z-direction of at least 0.2 mm, preferably at least 0.3 mm, wherein the one or more adhesive layers (8.1-8.6) have a combined thermal expansion in the z-direction of at least 0.1 mm when heated from 20 ° C to 150 ° C, the thermal expansion preferably counteracting a pressure of at least 5 bar.

Description

The invention lies in the field of mechanical engineering. It concerns vehicle technology, namely vehicle brakes.

One focus of automobile manufacturers is to reduce fuel consumption and CO ₂ emissions. One aspect that can be improved in this regard is reducing the drag torque of the brakes. This means that while driving, in the non-braking state, the distance between the brake disc and pads should be guaranteed. This distance should be reached as soon as possible after releasing the brakes and then maintained. Solutions to reduce drag torque often have disadvantages in terms of braking effect and/or pedal feel. Some solutions include the use of special chamfers, gaskets or sealing grooves. One aspect to consider is that due to a hyperplastic homogeneous behavior of the sealing material, the seal pushes the piston back towards the disc after the brakes are released.

In view of this, it is an object of the invention to reduce the drag torque and to enable maintenance of a desired gap between the pads and the disc surface.

This is achieved, for example, by a brake pad according to claim 1 or by a brake pad as described below. Advantageous embodiments can be found in the dependent claims as well as in the following description and the figures.

A brake block for a vehicle brake is proposed. The brake pad includes a backing plate, a backing layer, and a friction material arranged in this order along a Z direction. The brake pad is designed to be moved in the Z direction to be pressed against a rotating body for braking. The brake pad also includes one or more adhesive layers. Each of the one or more adhesive layers has a thickness in the z direction of at least 0.2 mm. Optionally, the thickness in the z direction can be at least 0.3 mm. The one or more adhesive layers have a combined thermal expansion in the z-direction of at least 0.1 mm when heated from 20°C to 150°C. Optionally, this thermal expansion counteracts a pressure of at least 5 bar.

Providing the above-mentioned thermal expansion properties to the one or more adhesive layers may facilitate retraction of the brake pad and/or maintenance of a desired gap. When the brake pad heats up during braking due to friction between the friction material and the rotating body, the one or more adhesive layers expand, which can result in increased braking pressure. After the brakes are released, the brake pads cool, resulting in contraction of the one or more adhesive layers in the z direction, pulling the friction material away from the rotating body.

The one or more adhesive layers are preferably made from a material or materials whose thermal expansion exceeds their compressibility at the typical temperatures and pressures encountered during braking. At a certain pressure that the brake pad exerts on the rotating body, such as 5 bar, a temperature increase to, for example, 150°C is expected. The thermal expansion at 150°C is then, for example, large enough to counteract the pressure of 5 bar, so that the result is an expansion of the at least one adhesive layer. After braking, the one or more adhesive layers cool and contract so that the desired gap between a friction surface of the rotating body and the friction material of the brake pad is restored.

• - eine erste Klebeschicht, die zwischen der Rückplatte und einer Shim angeordnet ist, und/oder
• - eine zweite Klebeschicht, die zwischen einer ersten Schicht der Shim und einer zweiten Schicht der Shim angeordnet ist, und/oder
• - eine dritte Klebeschicht, die zwischen der Rückplatte und der Unterschicht angeordnet ist, und/oder
• - eine vierte Klebeschicht, die zwischen der Unterschicht und dem Reibmaterial angeordnet ist, und/oder
• - eine fünfte Klebeschicht, die zwischen einer ersten Schicht der Rückplatte und einer zweiten Schicht der Rückplatte angeordnet ist.

The one or more adhesive layers may, for example, comprise at least one of the following:

• - a first adhesive layer arranged between the backplate and a shim, and / or
• - a second adhesive layer, which is arranged between a first layer of the shim and a second layer of the shim, and / or
• - a third adhesive layer arranged between the backplate and the backing layer, and/or
• - a fourth adhesive layer arranged between the underlayer and the friction material, and / or
• - a fifth adhesive layer disposed between a first layer of the backplate and a second layer of the backplate.

It is understood that the designations "first", "second", etc. represent a nomenclature and do not establish a hierarchy. That is, each of the first to fifth adhesive layers can stand alone, or they can be combined in any possible combination with a total of two, three, four or five adhesive layers. The shim can optionally be included in the brake block, for example if the first adhesive layer and/or the second adhesive layer is provided in the above sense. Similarly, the backplate may optionally include the first and second layers when the fifth adhesive layer is provided.

In one example, the second adhesive layer is disposed between the first layer of shim and the second layer of shim, one of the first layer and the second layer of the shim being made of metal or steel and the other of the first layer and the second layer of the shim being made of rubber is manufactured.

In one example, the fifth adhesive layer is disposed between the first layer of the backplate and the second layer of the backplate, wherein the first layer of the backplate and the second layer of the backplate are made of a different material from one another. For example, they can be made of different metals. For example, they can be made from different types of steel. One or both of these layers of the backplate may comprise, for example, metal and/or steel and/or cast iron and/or phenol and/or aluminum.

The one or more adhesive layers may, for example, have a combined thickness of at least 0.6 mm. Alternatively or additionally, at least one of the one or more adhesive layers may have a thickness of at least 0.6 mm.

For example, each of the one or more adhesive layers may have a thickness of at most 1 mm or at most 0.8 mm. Additionally or alternatively, the one or more adhesive layers may have a combined thickness of at most 1 mm.

The one or more adhesive layers may, for example, have a combined thermal expansion in the z direction of at least 0.12 mm and/or at most 0.3 mm when heated from 20 ° C to 150 ° C.

The thermal expansion can, for example, counteract a pressure of at least 5 bar, at least 10 bar, at least 15 bar or at least 20 bar. The thermal expansion can also occur if an appropriate pressure is applied to the brake pad, which acts in the opposite direction of the expansion, i.e. H. which compresses the brake pad.

At a constant temperature, the one or more adhesive layers can, for example, have a combined compression or an individual compression of 5 μm at 5 bar and/or of 8 μm at 20 bar and/or of 12 μm at 70 bar and/or of 15 μm 120 bar.

• Die eine oder mehreren Klebeschichten können einen Elastomerklebstoff enthalten.
• Die eine oder mehreren Klebeschichten können einen harten Elastomerklebstoff enthalten. Der harte Elastomerklebstoff kann Kieselsäure und/oder Kristalle enthalten, vorzugsweise einen hohen Anteil an Kieselsäure und/oder Kristallen.
• Die eine oder mehreren Klebeschichten können einen weichen Strukturklebstoff enthalten.
• Die eine oder mehreren Klebeschichten können einen harten Strukturklebstoff enthalten.
• Die eine oder mehreren Klebeschichten können einen Warmklebstoff enthalten.
• Die eine oder mehreren Klebeschichten können einen Heißschmelzklebstoff enthalten.
• Die eine oder mehreren Klebeschichten können einen druckempfindlichen Klebstoff (PSA) enthalten.
• Die eine oder mehreren Klebeschichten können einen kaltharten Elastomerklebstoff enthalten.
• Die eine oder mehreren Klebeschichten können z. B. Epoxid-Dicyandiamid enthalten, zum Beispiel als Warmklebstoff.
• Die eine oder mehreren Klebeschichten können z. B. Epoxid-Polyaminoamid enthalten, zum Beispiel als Warmklebstoff.
• Die eine oder mehreren Klebeschichten können z. B. Epoxid-Phenol enthalten, zum Beispiel als Warmklebstoff.
• Die eine oder mehreren Klebeschichten können z. B. Phenol-Polyvinyl enthalten, zum Beispiel als Warmklebstoff.
• Die eine oder mehreren Klebeschichten können z. B. Anaerob-Cyanacrylat enthalten, zum Beispiel als Kaltklebstoff.

The one or more adhesive layers can, for example, contain at least one of the components listed below:

• The one or more adhesive layers may contain an elastomeric adhesive.
• The one or more adhesive layers may contain a hard elastomer adhesive. The hard elastomer adhesive may contain silica and/or crystals, preferably a high proportion of silica and/or crystals.
• The one or more adhesive layers may contain a soft structural adhesive.
• The one or more adhesive layers may contain a hard structural adhesive.
• The one or more adhesive layers can contain a hot adhesive.
• The one or more adhesive layers may contain a hot melt adhesive.
• The one or more adhesive layers may contain a pressure sensitive adhesive (PSA).
• The one or more adhesive layers may contain a cold-hard elastomer adhesive.
• The one or more adhesive layers can e.g. B. contain epoxy dicyandiamide, for example as a hot adhesive.
• The one or more adhesive layers can e.g. B. contain epoxy polyaminoamide, for example as a hot adhesive.
• The one or more adhesive layers can e.g. B. contain epoxy phenol, for example as a hot adhesive.
• The one or more adhesive layers can e.g. B. contain phenol-polyvinyl, for example as a hot adhesive.
• The one or more adhesive layers can e.g. B. contain anaerobic cyanoacrylate, for example as a cold adhesive.

For example, at least one of the one or more adhesive layers can be made of a homogeneous and/or isotropic material.

For example, at least one of the one or more adhesive layers may have a coefficient of thermal expansion of at least 5E-6 1/K and/or at most 7E-6 1/K.

For example, at least one of the one or more adhesive layers may have a modulus of elasticity of at least 80 MPa or at least 90 MPa and/or at most 120 MPa or at most 110 MPa.

For example, at least one of the one or more adhesive layers may have a shear modulus of at least 30 MPa or at least 35 MPa and/or at most 50 MPa or at most 45 MPa.

For example, at least one of the one or more adhesive layers may have a Poisson's ratio of at least 0.35 or at least 0.4 and/or at most 0.55 or at most 0.5.

For example, at least one of the one or more adhesive layers may have a thermal expansion of 5E-6 1/K to 9E-6 1/K when heated. Additionally or alternatively, at least one of the one or more adhesive layers may have a thermal contraction of 1E-6 1/K to 3E-6 1/K upon cooling.

For example, a resistance to compressibility of at least one of the one or more adhesive layers may be at least 0.08 mm ³ /bar and/or at most 0.1 mm ³ /bar.

The invention will now be explained by way of example with reference to the accompanying figures.

• 1 zeigt ein Scheibenbremssystem,
• 2 a-e zeigen verschiedene Ausführungsformen eines Bremsklotzes mit einer oder mehreren Klebeschichten, und
• 3a, b illustrieren eine Wärmeausdehnung einer Klebeschicht.

In the figures:

• 1 shows a disc brake system,
• 2 ae show various embodiments of a brake pad with one or more adhesive layers, and
• 3a, b illustrate thermal expansion of an adhesive layer.

1 shows a disc brake system comprising a rotating body in the form of a brake disc 7 and a brake caliper 5. The brake caliper 5 holds a piston 6 and two brake pads which are adapted to be pressed against the brake disc 7. The brake pad on the right side, connected to the piston 6, is configured to be moved in a positive z direction for braking, as indicated by an arrow, and the opposite brake pad, which is moved by a finger of the brake caliper 5 is held is configured to move in a negative z direction for braking. After releasing the brakes, both brake pads are moved away from the brake disc 7 and they should resume and maintain their non-braking position as reliably as possible to avoid drag torque. Each brake pad includes a back plate 1, a backing layer 2 and a friction material 3, which are stacked in this order along the z-direction (positive z-direction for the brake pad on the right and a mirror image negative z-direction for the brake pad on the left Page). Each of the brake pads also includes a shim 4, which is arranged on the back plate 1, facing away from the lower layer 2. Each of the brake pads is configured to be moved along the z-direction to be pressed against the brake disc 7 for braking.

As will be explained below, the brake pads comprise one or more adhesive layers 8.1-8.5. The adhesive layers 8.1-8.5 are shown and explained in the following figures. Each of the one or more adhesive layers 8.1-8.5 has a thickness in the z-direction of at least 0.3 mm. The one or more adhesive layers 8.1-8.5 have a combined thermal expansion in the z-direction of at least 0.1 mm when heated from 20 ° C to 150 ° C, the thermal expansion being at a pressure of at least 5 bar, preferably counteracts a pressure of 20 bar.

2a-2e show a number of possible positions at which the adhesive layers 8.1-8.5 can be applied according to the present application. Regarding the 2a-2e It should be noted that these embodiments can optionally be combined with one another. Specifically, according to the application, the brake pad can have one or more adhesive layers 8.1-8.5, the one or more adhesive layers as in one of 2a-2e are executed. Of course, there can be other adhesive layers in the brake block that are not adhesive layers in the sense defined above. In the 2a-e The right brake block is only shown as an example. All statements can also be transferred, mutatis mutandis, to the left brake block.

2a shows an embodiment in which a first adhesive layer 8.1 is an adhesive layer in the sense defined above, the first adhesive layer 8.1 being arranged between the back plate 1 and the shim 4 in order to produce an adhesive connection between the shim 4 and the back plate 1. The first adhesive layer 8.1 has a thermal expansion in the z-direction of between 0.12 mm and 0.3 mm when heated from 20 ° C to 150 ° C, counteracting a pressure of at least 5 bar. The first adhesive layer 8.1 has a thickness between 0.6 mm and 1 mm.

2 B shows a brake block in which a second adhesive layer 8.2 is provided as an adhesive layer in the sense defined above. The second glue Layer 8.2 is arranged between a first layer 4.1 of the shim 4 and a second layer 4.2 of the shim 4. For example, the first layer 4.1 of the shim 4, which faces the back plate 1, is made of steel and the second layer 4.2 of the shim 4, which z. B. facing the piston 6 or the brake caliper finger, made of rubber, or vice versa.

In the in 2 B In the embodiment shown, the first adhesive layer 8.1 is provided in addition to the second adhesive layer 8.2, the first adhesive layer being arranged between the back plate 1 and the shim 4, more precisely between the back plate 1 and the first layer 4.1 of the shim 4. It goes without saying that the first adhesive layer 8.1. is not necessarily present if the second adhesive layer 8.2. is available.

The first adhesive layer 8.1 and the second adhesive layer 8.2 have a combined thermal expansion in the z direction of between 0.12 mm and 0.3 mm when heated from 20 ° C to 150 ° C, counteracting a pressure of at least 5 bar.

The first adhesive layer 8.1 and the second adhesive layer 8.2 have a combined thickness of between 0.6 mm and 1 mm.

2c shows a brake block in which a third adhesive layer 8.3 is provided as an adhesive layer in the sense defined above. The third adhesive layer 8.3 is arranged between the back plate 1 and the lower layer 2 in order to produce an adhesive connection between the lower layer 2 and the back plate 1.

2d shows a brake block in which a fourth adhesive layer 8.4 is provided as an adhesive layer in the sense defined above. The fourth adhesive layer 8.4 is arranged between the lower layer 2 and the friction material 3 in order to produce an adhesive connection between the lower layer 2 and the friction material 3.

2e shows a brake block in which a fifth adhesive layer 8.5 is provided as an adhesive layer in the sense defined above. The fifth adhesive layer 8.5 is arranged between a first layer 1.1 of the back plate 1 and a second layer 1.2 of the back plate 1 in order to produce an adhesive connection between two back plate parts.

The first layer 1.1 of the back plate 1 and the second layer 1.2 of the back plate 1 are made of a different material. The first layer 1.1 of the back plate 1 comprises steel and/or cast iron and/or phenol and/or aluminum. The second layer 1.2 of the backplate 1 comprises steel and/or cast iron and/or phenol and/or aluminum.

• Jede der Klebeschichten 8.1-8.5 umfasst eines oder mehreres von: einem Elastomerklebstoff, einem harten Elastomerklebstoff, der Kieselsäure und/oder Kristalle enthält, einem weichen Strukturklebstoff, einem harten Strukturklebstoff, einem Warmklebstoff, einem Heißschmelzklebstoff, einem druckempfindlichen Klebstoff, einem kaltharten Elastomerklebstoff, Epoxid-Dicyandiamid, Epoxid-Polyaminoamid, Epoxid-Phenol, Phenol-Polyvinyl, Anaerob-Cyanacrylat.
• Jede der Klebeschichten 8.1-8.5 ist aus einem homogenen und isotropen Material gefertigt.
• Jede der Klebeschichten 8.1-8.5 hat einen Wärmeausdehnungskoeffizienten zwischen 5E-6 1/K und 7E-6 1/K, einen Elastizitätsmodul zwischen 90 MPa und 110 MPa, einen Schermodul zwischen 35 MPa und 45 MPa, eine Poissonzahl zwischen 0,4 und 0,5 und einen Widerstand gegen Kompressibilität zwischen 0,08 mm³/bar und 0,1 mm³/bar.

With reference to everyone 2a-e The adhesive layers 8.1-8.5 are designed as explained below:

• Each of the adhesive layers 8.1-8.5 comprises one or more of: an elastomeric adhesive, a hard elastomeric adhesive containing silica and/or crystals, a soft structural adhesive, a hard structural adhesive, a hot-melt adhesive, a hot-melt adhesive, a pressure-sensitive adhesive, a cold-hard elastomeric adhesive, epoxy -Dicyandiamide, epoxy-polyaminoamide, epoxy-phenol, phenol-polyvinyl, anaerobic cyanoacrylate.
• Each of the adhesive layers 8.1-8.5 is made of a homogeneous and isotropic material.
• Each of the adhesive layers 8.1-8.5 has a coefficient of thermal expansion between 5E-6 1/K and 7E-6 1/K, a modulus of elasticity between 90 MPa and 110 MPa, a shear modulus between 35 MPa and 45 MPa, a Poisson's ratio between 0.4 and 0 .5 and a resistance to compressibility between 0.08 mm ³ /bar and 0.1 mm ³ /bar.

When heated, each of the one or more adhesive layers 8.1-8.5 has a thermal expansion of 5E-6 1/K to 9E-6 1/K. When cooled, each of the adhesive layers 8.1-8.5 has a thermal contraction of 1E-6 1/K to 3E-6 1/K.

3a and b illustrate a braking process and its effect on an adhesive layer according to the application.

3a shows components of a braking system, including a brake disc 7 and a brake pad, in a non-braking state, and 3b shows the same components in a braking state. The brake block contains an adhesive layer according to the application. The adhesive layer is, for example, the first adhesive layer 8.1, which is attached between the back plate 1 and the shim 4. The statements made here can also apply to the second, third, fourth and fifth adhesive layers if the second and/or third and/or fourth and/or fifth adhesive layers are additionally or alternatively provided.

In the non-braking state of 3a a gap g between the brake disc 7 and the brake block has a target gap width of 0.1 mm to 0.15 mm, which should be reliably restored and maintained. In the non-braking state, the adhesive layer 8.1 has a thickness d, where d is a value between 0.6 mm and 0.8 mm.

When the brakes are applied ( 3b) , the gap g disappears because the brake pad (ie the friction material 3) is pressed against the brake disc 7.

The heat generated by the friction causes the adhesive layer 8.1 to increase in thickness by Δd due to thermal expansion. This is in the enlarged view of 3b shown. The adhesive layer 8.1 is designed in such a way that when heated from 20 ° C to 150 ° C in the z direction it expands by 0.1 mm to 0.3 mm, this expansion in the axial z direction being subject to a pressure of 20 takes place in a counteracting manner. The heating and expansion occurs, for example, during a 15-second brake application. For example: Δd=0.12 mm.

After releasing the brake, the external load disappears and the heating of the adhesive layer 8.1 also ends. If the adhesive layer 8.1 assumes a lower temperature again, e.g. B. room temperature, the adhesive layer 8.1 returns to its original thickness d.

Reference symbol list

1

Backplate

2

Lower class

3

friction material

4

Shim

4.1

first layer of shim

4.2

second layer of shim

5

caliper

6

Pistons

7

Brake disc

8.1, 8.2, 8.3 8.4, 8.5

adhesive layer

Claims (16)

A brake pad for a vehicle brake, comprising a back plate (1), a backing layer (2) and a friction material (3) arranged in this order along a z-direction, the brake pad being adapted to be moved in the z-direction to be pressed against a rotating body for braking, the brake pad further comprising one or more adhesive layers (8.1-8.5), each of the one or more adhesive layers (8.1-8.5) having a thickness in the z-direction of at least 0.2 mm, preferably at least 0.3 mm, wherein the one or more adhesive layers (8.1-8.5) have a combined thermal expansion in the z-direction of at least 0.1 mm when heated from 20 ° C 150 ° C are heated, the thermal expansion preferably counteracting a pressure of at least 5 bar. brake block Claim 1 , wherein the one or more adhesive layers (8.1-8.5) comprise at least one of the following: - a first adhesive layer (8.1) arranged between the back plate (1) and a shim (4), and / or - a second adhesive layer (8.2), which is arranged between a first layer (4.1) of the shim (4) and a second layer (4.2) of the shim (4), and / or - a third adhesive layer (8.3), which is between the back plate (1) and the lower layer (2) is arranged, and / or - a fourth adhesive layer (8.4), which is arranged between the lower layer (2) and the friction material (3), and / or - a fifth adhesive layer (8.5), which is between a first layer (1.1) of the back plate (1) and a second layer (1.2) of the back plate (1) is arranged. Brake pad according to one of the preceding claims, wherein the second adhesive layer (8.2) is arranged between the first layer (4.1) of the shim (4) and the second layer (4.2) of the shim (4), one of the first layer (4.1) and the second layer (4.2) of the shim (4) is made of metal or steel and the other of the first layer (4.1) and the second layer (4.2) of the shim (4) is made of rubber. Brake pad according to one of the preceding claims, wherein the fifth adhesive layer (8.5) is arranged between the first layer (1.1) of the back plate (1) and the second layer (1.2) of the back plate (1), the first layer (1.1) of the back plate (1) and the second layer (1.2) of the back plate (1) are made of a different material. Brake pad according to one of the preceding claims, wherein the one or more adhesive layers (8.1-8.5) have a combined thickness of at least 0.6 mm and/or wherein at least one of the one or more adhesive layers (8.1-8.5) has a thickness of at least 0. 6 mm. Brake pad according to one of the preceding claims, wherein each of the one or more adhesive layers (8.1-8.5) has a thickness of at most 1 mm, preferably at most 0.8 mm, and / or wherein the one or more adhesive layers (8.1-8.5) have a have a combined thickness of no more than 1 mm. Brake pad according to one of the preceding claims, wherein the one or more adhesive layers (8.1-8.5) have a combined thermal expansion in the z-direction of at least 0.12 mm and/or at most 0 when heated from 20°C to 150°C. 3 mm. Brake pad according to one of the preceding claims, wherein the thermal expansion counteracts a pressure of at least 10 bar, or at least 15 bar, or at least 20 bar. Brake pad according to one of the preceding claims, wherein the one or more adhesive layers (8.1-8.5) has at least one of the following: - an elastomer adhesive and/or - a hard elastomer adhesive, which preferably contains silica and/or crystals, and/or - a soft structural adhesive, and/or - a hard structural adhesive, and/or - a hot adhesive and/or - a hot melt adhesive and/or - a pressure-sensitive adhesive, and/or - a cold-hard elastomer adhesive and/or - Epoxy dicyandiamide and/or - Epoxy polyaminoamide and/or - Epoxy phenol and/or - Phenol-polyvinyl, and/or - Anaerobic cyanoacrylate. Brake pad according to one of the preceding claims, wherein at least one of the one or more adhesive layers (8.1-8.5) is made of a homogeneous and/or isotropic material. Brake pad according to one of the preceding claims, wherein at least one of the one or more adhesive layers (8.1-8.5) has a thermal expansion coefficient of at least 5E-6 1/K and/or at most 7E-6 1/K. Brake pad according to one of the preceding claims, wherein at least one of the one or more adhesive layers (8.1-8.5) has a modulus of elasticity of at least 80 MPa or at least 90 MPa and/or at most 120 MPa or at most 110 MPa. Brake pad according to one of the preceding claims, wherein at least one of the one or more adhesive layers (8.1-8.5) has a shear modulus of at least 30 MPa or at least 35 MPa and / or at most 50 MPa or at most 45 MPa. Brake pad according to one of the preceding claims, wherein at least one of the one or more adhesive layers (8.1-8.5) has a Poisson's ratio of at least 0.35 or at least 0.4 and/or at most 0.55 or at most 0.5. Brake pad according to one of the preceding claims, wherein at least one of the one or more adhesive layers (8.1-8.5) has a thermal expansion of 5E-6 1/K to 9E-6 1/K when heated and/or at least one of the one or more adhesive layers (8.1-8.6) has a thermal contraction of 1E-6 1/K to 3E-6 1/K when cooled. Brake pad according to one of the preceding claims, wherein the resistance to compressibility of at least one of the one or more adhesive layers (8.1-8.5) is at least 0.08 mm ³ /bar and/or at most 0.1 mm ³ /bar.

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