METHOD FOR PRODUCING A MULTI-LAYER WET RUNNING FRICTION MATERIAL

Description

[0001] The invention relates to a method for producing a multi-layer wet friction material with at least one base layer and at least one top layer which are bonded together in a material-bonded manner.

[0002] US 5 585 166 A discloses a method for manufacturing a friction lining with fluid cooling.

[0003] EP 0 971 151 B1 discloses a method for producing a wet-running, two-layer, high-performance friction material.

[0004] JP 2002 001 749 A discloses the manufacture of decorative surfaces, such as decorative panels for building floors, building walls or ceilings, for furniture, etc., but does not explicitly disclose the manufacture of wet-running friction materials.

[0005] European patent EP 0 807 766 B1 discloses a method for producing asbestos-free friction material, comprising forming a first layer with oil-absorbing fibers and / or fillers, and bonding a second layer to the first layer, wherein the second layer comprises temperature-resistant and high-strength fibers and / or friction-modifying materials, and wherein the first layer has a lower density than the second layer.

[0006] European patent EP 0 854 305 B1 discloses a method for producing an asbestos-free friction material, comprising the following steps: forming a primary layer comprising nonlinear elastic fibers, cotton fibers and filler material, and bonding a secondary layer to the primary layer, wherein the secondary layer comprises aramid fibers, optionally filler material and optionally synthetic graphite, and wherein the secondary layer further comprises cotton fibers and porous carbon particles.

[0007] The object of the invention is to simplify the production of a multi-layer wet-running friction material with at least one base layer and at least one top layer that are bonded together by material interlocking.

[0008] This problem is solved by a method having the features according to claim 1.

[0009] The challenge in a process for manufacturing a multi-layer wet-running friction material with at least one underlayer and at least one toplayer, which are bonded together, is solved by first manufacturing the underlayer and the toplayer independently of each other from different materials before bonding the underlayer to the toplayer. The underlayer is also referred to as the underlayer. The toplayer is also referred to as the overlayer. The material manufacturing process is decoupled from the multi-layer process. This means that the friction material for the underlayer is manufactured independently of the friction material for the toplayer. Thus, the manufacturing process for the friction material has all degrees of freedom without being restricted by the multi-layer process.The separately manufactured friction materials for the base and top layers are subsequently bonded together in an additional process, such as lamination or coating, to form the multi-layered wet-running friction material. The claimed process is characterized, among other things, by the fact that the different materials are bonded together using temperature and pressure in a continuous or discontinuous process. The bond is achieved either through a binder material already present in some materials or through a binder material specifically applied to the interface between two layers. Depending on the requirements, the interface between two layers can be designed to be dense, i.e., impermeable to fluids, or porous, i.e., permeable to fluids.

[0010] A preferred embodiment of the process is characterized in that the backing and the top layer are produced from different formulations and supplied as raw paper. The backing and the top layer are preferably each produced in a papermaking process with two headboxes, but are not directly joined together. Instead, after production, they are wound, for example, onto coils, from which the raw paper for the backing and the top layer are then supplied in a subsequent process or process step.

[0011] The process according to the invention is characterized by a top layer formulation comprising 20 to 60 percent filler, 10 to 40 percent cellulose, 5 to 10 percent aramid, and 25 to 35 percent phenolic resin; and by a backing formulation comprising 10 to 50 percent filler, 10 to 40 percent cellulose, 5 to 10 percent aramid, 5 to 15 percent carbon, and 25 to 35 percent phenolic resin. The friction material is advantageously used to produce friction lining thicknesses of less than one millimeter. Friction linings produced with the wet-running friction material are, for example, 0.6 millimeters or 0.75 millimeters thick.

[0012] Another preferred embodiment of the method is characterized in that the substrate has a basis weight of one hundred to two hundred grams per square meter, wherein the top layer has a basis weight of two hundred to four hundred grams per square meter. These basis weights have proven to be particularly advantageous in tests with the claimed method.

[0013] According to the invention, the method is characterized in that the substrate is coated with a binder material before the substrate coated with the binder material is bonded to the top layer. The bonding of the substrate to the top layer preferably takes place under pressure and under the influence of temperature or heat.

[0014] Another preferred embodiment of the method is characterized in that the substrate is coated with a resin powder as a binder material. A powder coating using phenolic resin powder is particularly preferred for coating the substrate with the binder material.

[0015] Another preferred embodiment of the method is characterized in that the different materials are joined together by means of temperature and pressure. The pressure is applied, for example, by rolling or pressing. The temperature can be supplied by heat input, for example, via radiant heat.

[0016] Another preferred embodiment of the method is characterized in that the substrate, preferably coated with a binder material, is bonded to the top layer in a lamination or laminating process. For this purpose, the two layers together with the binder material can, for example, be passed between two rollers, in particular two preferably heated calender rollers.

[0017] According to the invention, the method is characterized in that the base layer, preferably coated with a binder material, is bonded to the top layer in a double-belt press. Good results have already been achieved with the double-belt press in trials conducted within the scope of the present invention. In the double-belt press, the two layers are advantageously heated using suitable heating devices. Furthermore, the bonded layers are subsequently cooled in the double-belt press using suitable cooling devices. The finished wet friction material can then be wound, for example, onto a suitable roll before further processing, such as by stamping.

[0018] This document also describes a plant for producing a multi-layer wet friction material with at least one base layer and at least one top layer, which are bonded together according to a previously described method. The plant advantageously includes a double-belt press into which different raw papers are fed from coils. The plant further advantageously includes a powder coating device. A suitable binder material is supplied via the powder coating device.

[0019] The invention further relates to a wet-running friction material, which was produced in particular on a previously described system and according to a previously described method. The multilayer wet-running friction material is a fiber-based friction material for wet-running applications, such as in dual-clutch transmissions, automatic transmissions, motorcycle transmissions, single and holding clutches, differentials, hybrid clutches, torque converter clutches, and synchronizers.

[0020] Further advantages, features, and details of the invention will become apparent from the following description, in which various exemplary embodiments are described in detail with reference to the drawing. The drawing shows: Figure 1 a top layer on average; Figure 2 a substrate in cross-section; Figure 3 a schematic representation of a process step in the manufacture of a wet-running friction material; Figure 4a schematic representation of a further process step in the production of a wet-running friction material; Figure 5 the wet-running friction material in cross-section; and Figure 6 a plant for the production of the wet running friction material.

[0021] In Figure 1 is a top layer 1 for the production of a in Figure 5 The wet-running friction material, designated with 14, is shown in simplified cross-section. Figure 2 is a document 2 for the production of the in Figure 5 The wet-running friction material, designated 14, is shown in simplified cross-section. The top layer 1 and the bottom layer 2 are produced independently of each other using a conventional papermaking process, also referred to simply as the paper process.

[0022] In Figure 3The schematic diagram shows that in the production of the wet friction material 14, the base 2 is first fed to a conveyor belt 3. The conveyor belt 3 is driven by means of two transport rollers 4, 5.

[0023] Using two binder rollers 6, 7, a binder material 8 is applied to the substrate 2 in the form of a binder layer 9. The top layer 1 is then applied to the binder layer 9. This results in a semi-finished product 10 in which the binder layer 9 has not yet hardened.

[0024] The binder material is an adhesive, for example, a resin, in particular a phenolic resin. The adhesive, especially the resin, hardens under the influence of heat, so that the substrate 2 is bonded to the top layer 1 via the binder material layer 9 in a materially bonded and stable manner.

[0025] In Figure 4 It is schematically indicated that the semi-finished product 10 consists of Figure 3The material is passed between two calender rolls 11, 12 to bond the top layer 1 to the base layer 2 using the binder material layer 9. The calender rolls 11, 12 are advantageously heated to supply the binder material layer 9 with the heat required for curing. This results in an intermediate product 13. Figure 5 The wet-running friction material 14 is shown schematically in cross-section. The top layer 1 is bonded to the base layer 2 by means of the binder material layer 9. The base layer 1 and the top layer 2 are made of different materials.

[0026] The separately produced materials are combined in an additional process, for example in the one in Figure 4 the indicated lamination or laminating process, to which in Figure 5The multilayered material shown is bonded together. This process is characterized by the fact that the different materials are bonded together using pressure and temperature in a continuous or discontinuous process.

[0027] In Figure 6 A schematic diagram shows a plant 20 for the production of the wet-running friction material 14. The plant 20 comprises two coils 21, 22, through which different raw papers 23, 24 are fed.

[0028] The English term "coil" refers to a spool, roll, or cylinder onto which the different raw papers 23 and 24 are wound. Raw paper 23 serves as the base layer 2 of the wet friction material 14. Raw paper 24 serves as the top layer 1 of the wet friction material 14.

[0029] The system 20 comprises a powder coating device 27. The powder coating device 27 includes a powder spreader 28, through which a resin powder 29 is applied to the substrate 2. The resin powder 29 serves to form the binder material layer 8 on the substrate 2.

[0030] The system 20 further comprises a double belt press 33 with two belts 31, 32, which are driven by drive rollers not specified in detail. The substrate 2 with the binder material 8 is first fed to the Figure 6 The material is fed to the tape 31 located below. Then the raw paper 24 is fed to form the top layer 1. An optional heating device 30 can be used to heat the binder material 8 on the base 2 before the raw paper 24 is fed in.

[0031] After the raw paper 24 is fed in, the two raw papers 23 and 24 together with the binder material 8 are passed between the belts 31, 32 of the double-walled press 33.

[0032] The double belt press 33 is in Figure 6 The top and bottom are equipped with heating devices 36, 37 and cooling devices 34, 35. The heating device 36 is in Figure 6 The cooling device 35 is located below, that is, below the base 2. Figure 6 also located below, that is, below the base 2. The cooling device 37 is in Figure 6 The cooling device 34 is located above, that is, above the top layer 1. Figure 6 also arranged above the top layer 1.

[0033] The heating devices 36, 37 supply heat to the raw papers 23, 24 and the binder material 8 arranged between them. The supplied heat causes resin components, in particular phenolic resin components, to harden in the base 2, the top layer 1, and the binder material 8, resulting in a stable composite that constitutes the wet-running friction material 14. The cooling devices 34, 35 cool the hardened wet-running friction material 14. The cooled wet-running friction material 14 is then wound onto a roll 38. Reference symbol list

[0034] 1 Top layer 2 Bottom layer 3 Conveyor belt 4 Transport roller 5 Transport roller 6 Binder roller 7 Binder roller 8 Binder material 9 Binder material layer 10 Semi-finished product 11 Calender roller 12 Calender roller 13 Intermediate product 14 Wet friction material 20 Plant 21 Coil 22 Coil 23 Base paper 24 Base paper 27 Powder coating device 28 Powder spreader 29 Resin powder 30 Optional heating device 31 Belt 32 Belt 33 Double belt press 34 Cooling device 35 Cooling device 36 Heating device 37 Heating device 38 Roll

Claims

1. A method for producing a multi-layered wet friction material (14) for fibre-based friction materials in dual-clutch transmissions, automatic transmissions, motorcycle transmissions, single-clutch transmissions, holding clutches, hybrid clutches, torque converter clutches, differentials, or synchronizers, comprising at least one bottom layer (2) and at least one top layer (1), which are materially bonded together, characterized in that the bottom layer (2) and the top layer (1) are first produced independently of each other from different materials before the bottom layer (2) is bonded to the top layer (1), wherein the bottom layer (2) is coated with a binder material (8) before the bottom layer (2) coated with the binder material (8) is bonded to the top layer (1), characterized in that the bottom layer (2) coated with the binder material (8) is bonded to the top layer (1) in a double-belt press (33), wherein a top layer formulation comprises twenty to sixty percent filler, ten to forty percent cellulose, and five to ten percent aramid, and contains twenty-five to thirty-five percent phenolic resin and a base layer formulation comprises ten to fifty percent filler, ten to forty percent cellulose, five to ten percent aramid, five to fifteen percent carbon and twenty-five to thirty-five percent phenolic resin.

2. The method according to claim 1, characterized in that the bottom layer (2) and the top layer (1) are produced from different formulations and supplied as base papers (23, 24).

3. The method according to either one of the preceding claims, characterized in that the bottom layer (2) has a basis weight of one hundred to two hundred grams per square metre, wherein the top layer (1) has a basis weight of two hundred to four hundred grams per square metre.

4. The method according to any one of the preceding claims, characterized in that the bottom layer (2) is coated with a resin powder (29) as a binder material.