Polyamide-based sliding material with high molecular weight polyethylene as filler

Abstract

The invention relates to a polyamide-based sliding material (16) having at least one filler contained therein for improving the tribological properties, wherein the sliding material comprises polyethylene having an average molar mass of at least 0.5 million g / mol as a filler, and the proportion of polyethylene in the sliding material is 2 to 25 wt. %. The invention also relates to sliding bearing composite materials (10) comprising such a sliding material, and to a three-dimensional moulded body comprising such a sliding material. The invention also relates to methods for producing a sliding bearing composite material comprising a sliding material.

Description

[0001] Title: Sliding material based on polyamide with high-molecular-weight polyethylene as filler

[0002] Description

[0003] The invention relates to a polymer-based sliding material with fillers that influence the tribological properties.

[0004] Such sliding materials are known in the art in a variety of forms. Among them are PTFE-based or PA-based sliding materials, which contain fillers to influence the tribological properties.

[0005] For example, EP 2 563 590 B1 describes a fluoropolymer-based plain bearing material, for example based on PTFE, in which 5-25 vol.% boron nitride and 1-15 vol.% mixed-phase oxide pigments are added to the fluoropolymer, which is intended to improve wear resistance.

[0006] From DE 10 2016 122476 Al, a polyamide-based sliding material is also known which contains tin disulfide and / or calcium phosphate as filler.

[0007] Despite the variety of sliding materials described in the prior art, there is still a need for a sliding material that is cost-effective and also suitable for mixed friction applications as well as lubricated rotary and axial applications.

[0008] The invention is concerned with the task of providing a cost-effective sliding material with good friction properties and improved wear resistance.

[0009] This object is achieved by a sliding material having the features of claim 1. This is a polyamide-based sliding material with at least one filler contained in the polyamide base, in particular dispersed therein, in particular for improving the tribological properties of the sliding material. The at least one filler can in particular be designed to reduce a coefficient of friction of the sliding material and / or wear of the sliding material. The polyamide base forms in particular a polymer matrix in which the at least one filler is distributed. In this respect, the sliding material comprises a polyamide matrix and at least one filler contained in the polyamide matrix, in particular distributed.

[0010] In particular, the at least one filler is embedded at least in sections in the polyamide matrix.

[0011] According to the invention, the sliding material comprises polyethylene as a filler with an average molar mass (molar mass) of at least 0.5 million g / mol, with the proportion of polyethylene filler in the sliding material being 2 to 25 wt.%. The sliding material according to the invention is therefore a polyamide-based sliding material with polyethylene with an average molar mass (molar mass) of at least 0.5 million g / mol contained therein as a (polymeric) filler, in particular dispersed therein.

[0012] The proposed sliding material provides a new material optimized for friction properties. In particular, it has surprisingly been found within the scope of the invention that the proposed combination of polyamide as a matrix and high-molecular-weight polyethylene as a filler can improve the friction properties of known polyamide-based sliding materials, and the sliding material is also comparatively cost-effective and easy to process. Furthermore, the proposed sliding material is PFAS-free (i.e., free of per- and polyfluorinated chemicals), which promotes environmentally friendly production and disposal.

[0013] The proposed sliding material is suitable, for example, for applications in the automotive sector (e.g., steering gears, power steering, pedal bearings, seat guide rails, steering knuckle bearings, brake caliper bushings, tailgate bearings) or in general industrial applications (e.g., handling and lifting equipment, guideways, hydraulic cylinders, pneumatic devices, hydraulic motors). Other areas of application include, for example, ski lifts, medical devices, textile machinery, or agricultural equipment. In this context, the term "sliding material" refers in particular to a material designed for sliding stress, e.g., as the sliding layer of a plain bearing. In this respect, the sliding material is, in particular, a surface material.

[0014] The term "polyamide base" or "polyamide matrix" does not necessarily mean that the entire polymer base or polyamide matrix must consist of polyamide (one type or a mixture of different polyamides). However, the polyamide base preferably consists of at least 80.0 wt.%, more particularly at least 90.0 wt.%, more particularly at least 95.0 wt.%, of polyamide (one type or a mixture of different polyamides).

[0015] It is particularly advantageous if the polyamide base consists of 100% polyamide. This does not exclude the possibility that the polyamide base may contain undesirable impurities, in particular up to 1.0% by weight, preferably up to 0.5% by weight, more preferably up to 0.2% by weight.

[0016] The polyamide base or the polyamide portion of the polyamide base may consist of one type of polyamide, in particular polyamide 4.6 (hereinafter PA4.6) or polyamide 6 (hereinafter PA6), preferably PA6.

[0017] The polyamide base or the polyamide portion of the polyamide base can also consist of a mixture of different polyamides.

[0018] The polyamide base or the polyamide portion of the polyamide base preferably comprises PA4.6 and at least one other polyamide different from PA4.6, in particular PA6 and / or PA6.6. The polyamide base particularly preferably consists of a mixture of PA4.6, PA6.6, and PA6.

[0019] In particular, the proportion of the polyamide base in the sliding material is at least 60 wt.%, in particular at least 65 wt.%, more particularly at least 70 wt.%, more particularly at least 75 wt.%, more particularly at least 80 wt.%. In particular, the sliding material consists of a maximum of 40 wt.% fillers, the remainder being polyamide base. It proves particularly advantageous if the proportion of polyethylene in the sliding material is 2 to 20 wt.%, in particular 5 to 20 wt.%, more particularly 2 to 15 wt.%, more particularly 5 to 15 wt.%.

[0020] Furthermore, it proves advantageous for improved wear resistance if the polyethylene has an average molar mass of at least 1.5 million g / mol, in particular at least 2.0 million g / mol, more particularly at least 5.0 million g / mol. In particular, the polyethylene has an average molar mass of at most 10.0 million g / mol. In this respect, the polyethylene is in particular high-molecular-weight polyethylene (HMW-PE) or ultra-high-molecular-weight polyethylene (UHWM-PE).

[0021] It is also particularly advantageous if the polyethylene is a functionalized polyethylene. In this respect, the polyethylene can contain functional groups, in particular carboxylic acid groups or carboxylic acid anhydride groups. Preferably, the polyethylene is a carboxylic acid and / or carboxylic acid anhydride-functionalized polyethylene. Particularly preferably, the polyethylene is a maleic acid-functionalized or maleic acid anhydride-functionalized polyethylene. Further advantageous functional groups are itaconic acid and its derivatives, in particular its anhydride, and / or citraconic acid and its

[0022] Derivatives, especially their anhydride. The functional groups can be introduced, for example, by copolymerization or by a grafting reaction. Such functionalization can increase the adhesion of the sliding material to a substrate.

[0023] It is conceivable that the sliding material contains polyethylene as the only polymeric filler or as the only filler at all.

[0024] In a preferred embodiment of the sliding material with polyethylene as the only relevant filler, the sliding material can consist of

[0025] - 15 to 25 wt.%, in particular 17.5 to 22.5 wt.%, preferably 20 wt.% of the polyethylene (with an average molar mass of at least 0.5 million g / mol, in particular at least 1.5 million g / mol, more particularly at least 2.0 million g / mol, more particularly at least 5.0 million g / mol) as filler and

[0026] - Remainder polyamide base. This does not exclude the possibility that the sliding material may contain unavoidable impurities up to 1.0 wt.%, preferably up to 0.5 wt.%, more preferably up to 0.1 wt.%. It has proven particularly advantageous in this context if the polyamide base comprises, in particular consists of, a mixture of polyamide 4.6 and at least one other polyamide different from polyamide 4.6, in particular polyamide 6.6 and / or polyamide 6.

[0027] It is also conceivable for the sliding material to contain at least one further filler in addition to the polyethylene. The at least one further filler can be selected from the group comprising: calcium phosphate, metal sulfide, in particular SnS2 and / or WS2, barium sulfate (BaSO4), solid lubricants, in particular graphite, and combinations thereof.

[0028] In an advantageous embodiment, the sliding material comprises:

[0029] - 2 to 20 wt.%, in particular 2 to 15 wt.%, further in particular 5 to 15 wt.%, further in particular 5 to 10 wt.%, polyethylene (with an average molar mass of at least 0.5 million g / mol, in particular at least 1.5 million g / mol, further in particular at least 2.0 million g / mol, further in particular at least 5.0 million g / mol) as filler, and

[0030] - 2 to 25 wt.%, in particular 5 to 25 wt.%, further in particular 10 to 20 wt.%, of at least one further filler, in particular selected from the group comprising: barium sulfate (BaSO4), calcium phosphate, metal sulfide, in particular SnSj and / or WS2, solid lubricants, preferably graphite, and combinations thereof.

[0031] In this context, it has proven particularly advantageous if the ratio of the weight proportions of the at least one further filler, in particular of the further fillers in total, to polyethylene is 3:1 to 1:1, preferably 2:1.

[0032] The sliding material preferably comprises calcium phosphate and / or at least one metal sulfide as a further filler. The at least one metal sulfide can in particular be SnS1, WS2, MOS2, bismuth sulfide and combinations thereof, preferably SnS2 and / or WS2. The wear resistance of the sliding material can be improved by adding calcium phosphate and / or metal sulfide. In particular, the proportion of calcium phosphate, the proportion of metal sulfide, or the proportion of a mixture of calcium phosphate and metal sulfide is a maximum of 15.0 wt.%, preferably a maximum of 10.0 wt.%, more preferably a maximum of 7.0 wt.%, more preferably a maximum of 5.0 wt.%, more preferably 1.0-10.0 wt.%, more preferably 1.0-7.0 wt.%, more preferably 1.0-5.0 wt.%, more preferably 3.0-7.0 wt.%, more preferably 3.0-5.0 wt.% of the sliding material.

[0033] A particularly preferred combination of fillers is the combination of polyethylene and a mixture of calcium phosphate and at least one metal sulfide, in particular a combination of polyethylene and a mixture of calcium phosphate, WS2 and SnS2.

[0034] In this respect, the sliding material can comprise a mixture of calcium phosphate, WS2, and SnS2 as further fillers (in addition to the polyethylene). The proportion of this mixture of calcium phosphate, WS2, and SnS2 is preferably a maximum of 15.0 wt.%, preferably a maximum of 10.0 wt.%, more preferably a maximum of 7.0 wt.%, more preferably a maximum of 5.0 wt.%, more preferably 1.0-10.0 wt.%, more preferably 1.0-7.0 wt.%, more preferably 1.0-5.0 wt.%, more preferably 3.0-7.0 wt.%, more preferably 3.0-5.0 wt.% of the sliding material.

[0035] A mixture of the following composition has proven to be preferred:

[0036] 70.0 - 97.0 wt.% calcium phosphate,

[0037] 2.0 - 20.0 wt.% SnS2,

[0038] 1.0 - 10.0 wt% WS2.

[0039] The sum of the proportions amounts to 100 wt.% (the percentages refer to the sum of the weights of the three components). Such filler compositions offer particularly good tribological properties, which particularly improve wear characteristics.

[0040] A mixture with the following composition has proven to be particularly preferred:

[0041] 88.0 wt% calcium phosphate,

[0042] 8.5 wt% SnS2,

[0043] 3.5 wt.% WS2. Furthermore, it proves advantageous if the sliding material, in particular in addition to calcium phosphate or a mixture of calcium phosphate and metal sulfide, comprises a solid lubricant as a further filler. ZnS, graphite, carbon black, or hexagonal BN have proven particularly advantageous as solid lubricants. The sliding material preferably comprises graphite as a solid lubricant. The proportion of solid lubricants, in particular graphite, is preferably 5.0-15.0 wt.%, preferably 5.0-10.0 wt.% of the sliding material.

[0044] In some embodiments, the sliding material can comprise barium sulfate (BaSO4) as a further filler, in particular in addition to calcium phosphate or a mixture of calcium phosphate, WS2, and SnS2. By adding BaSO4, the proportion of calcium phosphate and / or metal sulfide can be reduced, while maintaining essentially the same wear properties. The proportion of BaSO4 is preferably a maximum of 10.0 wt.%, more preferably a maximum of 5.0 wt.%, more preferably 1.0-10.0 wt.%, more preferably 1.0-5.0 wt.%, of the sliding material.

[0045] Additionally or alternatively, the fillers may comprise one or more functional substances. The at least one further functional substance may in particular be selected from the following group of functional substances:

[0046] - Reinforcing materials, such as carbon fibres, glass fibres, polymer fibres (in particular aramid fibres);

[0047] - Solid lubricants, such as ZnS, graphite, carbon black or hexagonal BN;

[0048] - Plastic particles, such as in particular aramid (PPTA), PPSO2, PI and PAI particles, polyacrylate particles (PAR), PBA particles, PBI particles, PEEK particles, PAEK particles, also as compounded fillers;

[0049] - metal oxides, such as in particular Fe2O3, AI2O3, SiO2, CrO2, TiO2, CuO, MgO, ZnO;

[0050] - Hard material particles, especially ceramic particles such as SiC, Si3N4, BC, cubic BN;

[0051] - PFAS-free fluorides, such as CaF2, NaF, AI F3;

[0052] - phyllosilicates, such as in particular kaolin, mica, wollastonite, talc, silica;

[0053] - metallic fine powders, in particular bronze and bismuth; and

[0054] - Pigments or mixed phase oxide pigments, such as in particular Co-Al, Cr-Sb-Ti, Co-Ti, Fe-Al or

[0055] Co-Cr. In this context, it may prove advantageous if the proportion of the additional functional substance, or the proportion of several additional functional substances in total, amounts to a maximum of 5 wt.% of the sliding material.

[0056] In an advantageous embodiment, the sliding material consists of:

[0057] - 2 to 20 wt.%, in particular 2 to 15 wt.%, further in particular 5 to 15 wt.%, further in particular 5 to 10 wt.%, polyethylene (with an average molar mass of at least 0.5 million g / mol, in particular at least 1.5 million g / mol, further in particular at least 2.0 million g / mol, further in particular at least 5.0 million g / mol) as filler;

[0058] - 2 to 25 wt.%, in particular 5 to 25 wt.%, further in particular 10 to 20 wt.%, of at least one further filler, in particular selected from the group comprising: barium sulfate (BaSO4), calcium phosphate, metal sulfide, in particular SnS2 and / or WS2, solid lubricants, preferably graphite, and combinations thereof;

[0059] - optionally at least one further of the above-mentioned functional substances as a filler, wherein the proportion of the at least one functional substance amounts to a maximum of 5% by weight of the sliding material;

[0060] - optionally unavoidable impurities in total up to 1.0 wt.%, preferably up to 0.5 wt.%, more preferably up to 0.1 wt.%;

[0061] - Rest polyamide base, in particular mixture of PA4.6 and at least one other polyamide different from PA4.6, further in particular PA6.6 and / or PA6.

[0062] Preferably, the proportion of fillers in the sliding material in total (i.e. in total) is a maximum of 40.0 wt.%, in particular a maximum of 35.0 wt.%, a maximum of 30.0 wt.%, in particular a maximum of 25.0 wt.%, further in particular a maximum of 20.0 wt.%, further in particular a maximum of 15.0 wt.%.

[0063] In a particularly advantageous embodiment, the sliding material comprises as fillers:

[0064] - 8 to 12 wt.%, preferably 10 wt.%, of the polyethylene (with an average molar mass of at least 0.5 million g / mol, in particular at least 1.5 million g / mol, more particularly at least 2.0 million g / mol, more particularly at least 5.0 million g / mol); - 8 to 12 wt.%, preferably 10 wt.%, calcium phosphate or a mixture of calcium phosphate and at least one metal sulfide, in particular SnSj and / or WS2

[0065] - 8 to 12 wt.%, preferably 10 wt.%, graphite.

[0066] In this context, it has proven particularly advantageous if the polyamide base consists of a mixture of PA4.6 and at least one other polyamide different from PA4.6, in particular PA6.6 and / or PA6. In particular, the polyamide base consists of a mixture of PA6, PA6.6, and PA4.6, in particular with a PA6:PA6.6:PA4.6 mass ratio of 8:5:1.

[0067] In particular, the sliding material consists of:

[0068] - 8 to 12% by weight, preferably 10% by weight, of the polyethylene (with an average molar mass of at least 0.5 million g / mol, in particular at least 1.5 million g / mol, more particularly at least 2.0 million g / mol, more particularly at least 5.0 million g / mol) as filler;

[0069] - 8 to 12 wt.%, preferably 10 wt.%, calcium phosphate or a mixture of calcium phosphate and at least one metal sulfide, in particular SnS2 and / or WS2 as filler

[0070] - 8 to 12% by weight, preferably 10% by weight, of graphite as filler;

[0071] - optionally at least one further of the above-mentioned functional substances as a filler, wherein the proportion of the at least one functional substance amounts to a maximum of 5% by weight of the sliding material;

[0072] - optionally unavoidable impurities in total up to 1.0 wt.%, preferably up to 0.5 wt.%, more preferably up to 0.1 wt.%;

[0073] - Remainder polyamide base, in particular a mixture of PA4.6 and at least one other polyamide different from PA4.6, more particularly PA6.6 and / or PA6. In particular, the polyamide base consists of a mixture of PA6, PA6.6, and PA4.6, in particular with a PA6:PA6.6:PA4.6 mass ratio of 8:5:1.

[0074] In a further particularly advantageous embodiment, the sliding material comprises as fillers:

[0075] 3.0 to 7.0 wt.%, in particular 5.0 wt.%, of the polyethylene (with an average molar

[0076] Mass of at least 0.5 million g / mol, in particular at least 1.5 million g / mol, further in particular at least 2.0 million g / mol, further in particular at least 5.0 million g / mol);

[0077] - 3.0 to 7.0 wt.%, in particular 5.0 wt.%, calcium phosphate or mixture of calcium phosphate and at least one metal sulfide, in particular SnS2 and / or WS2;

[0078] - 3.0 to 7.0 wt.%, in particular 5.0 wt.%, BaSO4;

[0079] In particular, the sliding material consists of:

[0080] - 3 to 7 wt.%, in particular 5 wt.%, of the polyethylene (with an average molar mass of at least 0.5 million g / mol, in particular at least 1.5 million g / mol, further in particular at least 2.0 million g / mol, further in particular at least 5.0 million g / mol) as filler;

[0081] - 3 to 7 wt.%, in particular 5 wt.%, calcium phosphate or mixture of calcium phosphate and at least one metal sulfide, in particular SnS2 and / or WS2, as filler;

[0082] - 3 to 7 wt.%, in particular 5 wt.%, BaSO4 as filler;

[0083] - optionally at least one further of the above-mentioned functional substances as a filler, wherein the proportion of the at least one functional substance amounts to a maximum of 5% by weight of the sliding material;

[0084] - optionally unavoidable impurities in total up to 1.0 wt.%, preferably up to 0.5 wt.%, more preferably up to 0.1 wt.%;

[0085] - Remainder polyamide base, in particular a mixture of PA4.6 and at least one other polyamide different from PA4.6, more particularly PA6.6 and / or PA6. In particular, the polyamide base consists of a mixture of PA6, PA6.6, and PA4.6, more particularly with a PA6:PA6.6:PA4.6 mass ratio of 4:2:11.

[0086] The sliding materials described above can be used in particular for producing a plain bearing composite material. In this respect, the invention also relates to a plain bearing composite material comprising the sliding material described above. The advantages and optional features described above in connection with the sliding material as such can also serve to design the plain bearing composite material. To avoid repetition, reference is therefore made to the above disclosure in this regard. According to a first advantageous aspect, the plain bearing composite material can comprise a support layer, in particular a metallic one, in particular made of steel or a copper alloy, a porous carrier layer, in particular made of bronze, preferably lead-free bronze, applied in particular directly to the support layer, and the sliding material described above, wherein the sliding material is impregnated into the porous carrier layer.Such a plain bearing composite material has a three-layer structure consisting of a support layer, a porous carrier layer applied to the support layer, and a sliding material impregnated into the porous carrier layer. The sliding material preferably forms a projection over the porous carrier layer.

[0087] To produce the above-described sliding bearing composite material according to the first aspect, the metallic support layer with the porous carrier layer applied thereto and the sliding material are first provided. In particular, the sliding material is provided in the form of a sliding material film (i.e., a film-like flat material made of sliding material). The sliding material or the sliding material film is then applied to the porous carrier layer and subsequently impregnated into the porous carrier layer, in particular by means of a hot-pressing process and / or rolling process. The sliding material is thus pressed into the carrier layer, in particular by applying heat.

[0088] According to a second, alternative advantageous aspect, the plain bearing composite material can have a support layer, in particular a metallic one, in particular made of steel, a coated steel, or a copper alloy, and a sliding layer made of a sliding material described above or comprising a sliding material described above, wherein the sliding layer or the sliding material is joined to the support layer by means of an adhesion promoter layer, in particular an adhesive layer. In this respect, the plain bearing composite material can comprise a support layer, in particular a metallic one, an adhesion promoter layer applied, in particular directly, to the support layer, and a sliding layer made of or comprising sliding material applied to the adhesion promoter layer. In advantageous embodiments, the support layer can be made of an aluminum alloy.

[0089] The sliding bearing composite material according to the second aspect comprises in particular no porous

[0090] Carrier layer or other reinforcement layers such as expanded metal or fabric. It was discovered in the invention that the use of polyethylene as a filler sufficiently improves the load-bearing capacity of the sliding layer, particularly its wear resistance, for use as a plain bearing element. A design with an adhesion promoter layer therefore facilitates a simple and cost-effective construction of the plain bearing composite material.

[0091] According to a third aspect, the sliding layer can also comprise a reinforcing structure, in particular a metallic one, preferably in the form of an expanded metal mesh or a fabric, in particular into which the sliding material is impregnated. In this respect, the sliding bearing composite material according to the third aspect can have a supporting layer, in particular a metallic one, in particular made of steel, a coated steel, or a copper alloy, a sliding layer comprising a reinforcing structure, in particular a metallic one, and a sliding material as described above, wherein the sliding layer is joined to the supporting layer by means of an adhesion promoter layer, in particular an adhesive layer. The reinforcing structure is preferably spaced from the supporting layer, in particular by the adhesion promoter layer and / or by the sliding material. This can result in advantageous stress conditions during sliding loading.The reinforcement structure can in particular be made of bronze.

[0092] It is also conceivable, in principle, for the sliding layer, especially the reinforcement structure, to be sintered onto the support layer. In this case, no additional adhesion promoter layer is required.

[0093] In the aforementioned plain bearing composite materials with an adhesion promoter layer, the adhesion promoter layer can, in particular, be applied directly to the support layer. The adhesion promoter layer is separate from the sliding layer or sliding material. As explained in more detail below, the adhesion promoter layer and the sliding layer can be provided as a film during the production of the plain bearing composite material. The sliding material and the adhesion promoter layer can also be coextruded.

[0094] The adhesion promoter layer can be an adhesive layer in each of the aspects mentioned. In this respect, the plain bearing composite material can have a support layer and a sliding layer made of a sliding material described above or comprising a sliding material described above, wherein the sliding layer is adhesively bonded to the support layer. The adhesion promoter layer is preferably a polymer layer. Within the scope of an advantageous embodiment, the adhesion promoter layer can comprise or consist of a polyolefin or mixtures of different polyolefins. Preferably, the adhesion promoter layer comprises or consists of polyethylene. Preferably, the adhesion promoter layer comprises or consists of polyethylene with an average molar mass (molar mass) of less than 1.0 million g / mol, in particular less than 0.5 million g / mol.It can be particularly advantageous if the adhesion promoter layer comprises or consists of thermoplastic polyethylene. The adhesion promoter layer can comprise a functionalized polyethylene. This can, for example, improve the bond between the adhesion promoter layer and thus the sliding material and the support layer.

[0095] The adhesion promoter layer can be provided separately from the sliding material during the production of the plain bearing composite. For example, the adhesion promoter layer can be provided as a film-like flat material made of adhesion promoter material (adhesion promoter film).

[0096] An advantageous method for producing such a plain bearing composite material according to the second or third aspect may comprise the following steps:

[0097] - Providing the support layer;

[0098] - Providing an adhesion promoter film made of an adhesion promoter material;

[0099] - Providing a sliding material film made of the sliding material described above or comprising a sliding material described above and a reinforcing structure described above, in particular expanded metal or fabric,

[0100] - Applying the adhesion promoter film to the support layer and applying the sliding material film to the adhesion promoter film or

[0101] Joining the adhesion promoter film and the sliding material film to form a sliding material-adhesion promoter film composite and applying the sliding material-adhesion promoter film composite to the support layer,

[0102] - Pressing the support layer, the adhesion promoter film, and the sliding material film, or the support layer and the sliding material-adhesion promoter-film composite, in particular by means of a hot-pressing process and / or a rolling process. It is also conceivable for the adhesion promoter layer and the sliding material to be provided as a material composite, e.g., by coextrusion. This sliding material-adhesion promoter composite can then be applied to the support layer and pressed with it to produce the sliding bearing composite material.

[0103] In this respect, an alternative advantageous method for producing a plain bearing composite material according to the second or third aspect may comprise the following steps:

[0104] - Providing the support layer;

[0105] - Providing a sliding material-adhesion promoter composite, in particular by means of coextrusion;

[0106] - Applying the sliding material-adhesion promoter composite to the support layer,

[0107] - Pressing the support layer and the sliding material-adhesion promoter composite, in particular by means of a hot pressing process and / or a rolling process.

[0108] The invention also encompasses a three-dimensional molded body consisting of or comprising a sliding material of the type described above. The molded body can be attached to a support part made of a different material. The molded body can be designed or used as a sliding bearing element or as a transmission component.

[0109] Preferably, the dimensions of the molded body are at least 1.0 mm in each dimension, in particular at least 2.0 mm, and more particularly at least 5.0 mm or at least 6.0 mm. Of course, the dimensions can also be much larger.

[0110] The sliding bearing composite material formed with the sliding material or the three-dimensional shaped body formed from or with the sliding material can be used in particular as a sliding bearing element. In this respect, the invention also encompasses a sliding bearing element made from a sliding bearing composite material of the types described above or comprising a shaped body described above.

[0111] The sliding bearing element can be, for example, a sliding strip, a sliding shoe, a

[0112] A sliding cushion, a plain bearing shell, a plain bearing bush or flanged bush.

[0113] The sliding element can also be a thrust ring or thrust washer. The sliding element can also be typically rolled cylindrical bushings or half-shell-shaped plain bearing elements manufactured with the plain bearing composite material. The plain bearing composite material can also be used to manufacture flanged bushings or cup bushings, or flat and spherical plain bearing elements.

[0114] The invention is explained in more detail below using examples and the figures. The drawings show:

[0115] Figure 1: a schematic sectional view of an embodiment of a plain bearing composite material according to a first aspect;

[0116] Figure 2: a schematic sectional view of an embodiment of a plain bearing composite material according to a second aspect;

[0117] Figure 3: a schematic sectional view of an embodiment of a plain bearing composite material according to a third aspect;

[0118] Figure 4: Diagram to explain the friction behavior of different plain bearing elements made of the plain bearing composite material.

[0119] Figure 1 shows a schematic sectional view of an embodiment of a plain bearing composite material, which is designated overall by the reference numeral 10.

[0120] In the example according to Figure 1, the plain bearing composite material 10 comprises a metallic support layer 12, typically made of steel or a copper alloy, and a porous carrier layer 14, in particular a bronze layer. The plain bearing composite material 10 also comprises a sliding material 16, as described above, which is impregnated into the porous carrier layer 14.

[0121] For example, the porous carrier layer 14 is made of a sintered layer of metallic particles 18 on

[0122] Bronze base. The particles of the carrier layer 14 form interconnected macroscopic cavities 20 (which are not shown to scale, however), into which the sliding material 16 is impregnated. As schematically shown in Fig. 1, the sliding material 16 essentially completely fills the pores 20 of the carrier layer 14 and forms a projection above the carrier layer 14.

[0123] As mentioned above, the sliding material 16 comprises a polymer base that forms the matrix of the sliding material 16. In the specific example, the polymer base is a polyamide base (see below for advantageous compositions).

[0124] The sliding material 16 also comprises at least one filler (not separately shown) incorporated into the matrix-forming polyamide base. As mentioned above, the sliding material 16 comprises at least polyethylene with an average molar mass of at least 0.5 million g / mol (see below for advantageous compositions).

[0125] As mentioned above, for producing the sliding bearing composite material 10 according to Figure 1, the sliding material 16 can be provided in the form of a foil-like flat material (sliding material foil), which is then impregnated into the porous carrier layer by means of a hot pressing process.

[0126] Figure 2 shows a simplified schematic representation of a further embodiment of a plain bearing composite material 10. In the example according to Figure 2, the plain bearing composite material 10 comprises a metallic support layer 12, typically made of steel, a coated steel, a copper alloy or an aluminum alloy, and a sliding layer 22 made of the sliding material 16 described above. The sliding material 16 is connected to the metallic support layer 12 via a polymeric adhesion promoter layer 24.

[0127] As mentioned above, for producing the sliding bearing composite material 10 according to Fig. 2, the sliding material 16 and the adhesion promoter layer 22 can each be provided as a film, which is then pressed and thus connected to the support layer 12 in a hot pressing process.

[0128] The adhesion promoter layer 24 can in particular comprise or consist of polyolefins, preferably polyethylene. By way of example and preferably, the adhesive layer 24 can comprise or consist of polyethylene with an average molar mass of less than 1.0 million g / mol, preferably less than 0.5 million g / mol.

[0129] Figure 3 shows a simplified schematic representation of a further embodiment of a plain bearing composite material 10. In the example according to Figure 3, the plain bearing composite material 10 comprises a metallic support layer 12, typically made of steel, a copper alloy, or an aluminum alloy, and a sliding layer 22, which now comprises, in addition to the sliding material 16, a reinforcing structure 26, for example in the form of a metallic expanded metal mesh. As indicated in Figure 3, the sliding material 16 is in particular impregnated into the reinforcing structure 26. The sliding layer 22, comprising the sliding material 16 and the reinforcing structure 26, is then joined to the support layer 12 by means of the aforementioned adhesion promoter layer 24.

[0130] As mentioned above, for producing the sliding bearing composite material 10 according to Figure 3, the reinforcing structure 26 with the impregnated sliding material 16 and the adhesion promoter layer can each be provided as a film, which is then pressed and thus connected to the support layer 12 in a hot pressing process.

[0131] The following table lists exemplary and preferred compositions of the sliding material 16. References include pure PA4.6 (Reference 1) and a known sliding material containing PTFE (Reference 2).

[0132] In the examples mentioned, the mixture of calcium phosphate, SnSj, and WS2 has, by way of example and preferably, the following composition: 88 wt.% calcium phosphate / 8.5 wt.% SnSz / 3.5 wt.% WS2. The UHMW-PE used in the examples has an average molar mass of 1.5-2.0 million g / mol (determined according to DIN EN ISO 16014).

[0133] Figure 4 shows the result of friction coefficient measurements on plain bearing elements (specifically bearing shell segments) which were manufactured from a plain bearing composite material 10 using sliding materials 16 of the above examples 1 to 3 and the references.

[0134] The friction values ​​were determined in a rotation test, in which the bearing shell segments with the sliding material 16 were pressed against a rotating steel shaft by a hydraulic cylinder. The test parameters are listed in the table below.

[0135] As can be seen from Figure 4, the use of UHMW-PE as a filler creates PFAS-free sliding materials with a low coefficient of friction.

Claims

Patent claims 1. Sliding material (16) based on polyamide with at least one filler contained therein to improve the tribological properties, characterized in that the sliding material (16) comprises polyethylene with an average molar mass of at least 0.5 million g / mol as filler, the proportion of polyethylene in the sliding material (16) being 2 to 25 wt.%.

2. Sliding material according to claim 1, wherein the proportion of polyethylene in the sliding material is 2 to 20 wt.%, in particular 5 to 20 wt.%, further in particular 5 to 15 wt.%.

3. Sliding material according to claim 1 or 2, wherein the polyethylene has an average molar mass of at least 1.5 million g / mol, in particular at least 2.0 million g / mol, further in particular of at least 5.0 million g / mol.

4. Sliding material according to one of the preceding claims, wherein the polyethylene is a functionalized polyethylene, in particular a carboxylic acid and / or carboxylic acid anhydride functionalized polyethylene, further in particular a maleic acid functionalized or maleic acid anhydride functionalized polyethylene.

5. Sliding material according to one of the preceding claims, wherein the polyamide base comprises a mixture of PA4.6 and at least one further polyamide different from PA4.6, in particular PA6 and / or PA6.

6.

6. Sliding material according to one of the preceding claims, consisting of - 15 to 25 wt.% polyethylene, in particular 17.5 to 22.5 wt.%, preferably 20 wt.%, as filler and - Rest polyamide base, in particular polyamide, preferably PA6.

7. Sliding material according to one of claims 1 to 5, comprising 2 to 20 wt.%, in particular 2 to 15 wt.%, further in particular 5 to 15 wt.%, further in particular 5 to 10 wt.%, polyethylene as filler; 2 to 25 wt.%, in particular 5 to 25 wt.%, more particularly 10 to 20 wt.%, of at least one further filler, wherein the at least one further filler is selected from the group comprising: Barium sulfate (BaSO4), calcium phosphate, metal sulfide, in particular SnS2 and / or WS2, solid lubricant, preferably graphite, and combinations thereof.

8. Sliding material according to the preceding claim, wherein a ratio of the weight proportions of the further filler or the sum of the further fillers to polyethylene is 3:1 to 1:1, preferably 2:

1.

9. Sliding material according to one of claims 1 to 5, further comprising - as a further filler - calcium phosphate and / or at least one metal sulfide, in particular a mixture of calcium phosphate, WS2 and SnS2, in particular wherein the proportion of calcium phosphate, the proportion of metal sulfide, or the proportion of a mixture of calcium phosphate and metal sulfide, in particular the mixture of calcium phosphate, WS2 and SnS2, is at most 15.0 wt.%, preferably at most 10.0 wt.%, more preferably at most 7.0 wt.%, more preferably at most 5.0 wt.%, more preferably 1.0 - 10.0 wt.%, more preferably 1.0 - 7.0 wt.%, more preferably 1.0 - 5.0 wt.%, more preferably 3.0 - 7.0 wt.%, more preferably 3.0 - 5.0 wt.%, of the sliding material.

10. Sliding material according to one of claims 1 to 5 or 9, further comprising - as a further filler - a solid lubricant, in particular ZnS, carbon black, or hexagonal BN, preferably graphite, in particular wherein the proportion of solid lubricants in the sliding material is 5.0 - 15.0 wt.%, preferably 5.0 - 10.0 wt.%, of the sliding material.

11. Sliding material according to claim 9, further comprising BaSO4 as a further filler, in particular wherein the proportion of BaSO4 is 1.0 - 10.0 wt.%, preferably 1.0 - 5.0 wt.%, of the sliding material.

12. Sliding material (16) according to one of the preceding claims, wherein the proportion of fillers in the sliding material in total is a maximum of 40.0 wt.%, in particular a maximum of 35.0 wt.%, a maximum of 30.0 wt.%, in particular a maximum of 25.0 wt.%, further in particular a maximum of 20.0 wt.%, further in particular a maximum of 15.0 wt.%.

13. Sliding material according to one of claims 1 to 5, comprising, as fillers: 8 to 12% by weight, preferably 10% by weight, of the polyethylene; 8 to 12 wt.%, preferably 10 wt.%, calcium phosphate or a mixture of calcium phosphate and at least one metal sulfide, in particular SnS2 and / or WS2, and 8 to 12 wt.%, preferably 10 wt.%, graphite, in particular wherein the polyamide base comprises a mixture of PA4.6 and at least one further polyamide different from PA4.6, in particular PA6.6 and / or PA6.

14. Sliding material according to one of claims 1 to 5, comprising, as fillers: 3 to 7 wt.%, in particular 5 wt.%, of the polyethylene, 3 to 7 wt.%, in particular 5 wt.%, calcium phosphate or mixture of calcium phosphate and at least one metal sulfide, in particular SnS2 and / or WS2, and 3 to 7 wt.%, in particular 5 wt.%, BaSO4, in particular wherein the polyamide base comprises a mixture of PA4.6 and at least one further polyamide different from PA4.6, in particular PA6.6 and / or PA6.

15. Plain bearing composite material (10), comprising - a support layer (12), in particular a metallic one, in particular made of steel or a copper alloy, and - a sliding material (16) according to one of the preceding claims.

16. Plain bearing composite material (10) according to the preceding claim, wherein the sliding material is joined to the support layer (12) by means of an adhesion promoter layer (24), in particular applied directly to the support layer (12).

17. Plain bearing composite material (10) according to the preceding claim, wherein the adhesion promoter layer is a polymer layer, in particular comprising a polyolefin, further in particular comprising polyethylene, further in particular comprising polyethylene with a molecular weight of less than 1.0 million g / mol, further comprising in particular thermoplastic polyethylene.

18. Plain bearing composite material (10) according to claim 15, further comprising a porous carrier layer (14), in particular made of bronze, preferably of lead-free bronze, applied in particular directly to the support layer (12), wherein the sliding material (16) is impregnated into the porous carrier layer (14) and in particular forms a projection over the porous carrier layer (14).

19. Three-dimensional shaped body for sliding stress consisting of a sliding material (16) according to one of claims 1 to 14.

20. Sliding bearing element made of a sliding bearing composite material (10) according to one of Claims 15 to 18 or comprising a shaped body according to claim 19.

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