Thermoplastic compositions of polyether ether ketone with improved tribological material properties and use thereof

Abstract

The invention relates to a thermoplastic component comprising a matrix component A) and a filler component B), wherein the matrix component A) is a polyether ether ketone, the filler component B) comprises inorganic particles and carbon-containing particles, and the overall composition comprises equal or different parts of hydrophobic silica, carbon fibers, titanium dioxide particles, graphite particles and a particle lubricant selected from divalent metal sulfides and alkaline earth metal sulfates as filler component B).

Description

[0001] The present invention relates to a thermoplastic composition comprising a matrix component A) and a filler component B), wherein the matrix component A) comprises polyetheretherketone, the filler component B) comprises inorganic particles and carbonaceous particles, and the overall composition comprises equal or different portions of hydrophobic silica, carbon fibers, titanium dioxide particles, graphite particles and a particulate lubricant selected from divalent metal sulfides and alkaline earth metal sulfates.

[0002] EP1511624B1, EP1511625B1 and EP1526296B1 disclose the preparation of polyetheretherketone for producing a sliding bearing composite material with a metallic protective layer, wherein the sliding bearing composite material comprises a sliding layer material based on PEEK with zinc sulfide and / or barium sulfate, carbon fibers, graphite particles and titanium dioxide for modifying the material properties of the polymer matrix.

[0003] To reduce CO2 and minimize energy requirements, there is an increasing demand for lightweight, high-performance materials whose properties are comparable to those of metals in tool making, the automotive industry, and aircraft construction in order to replace them.

[0004] Furthermore, certain selected fillers and their anisotropic arrangement can have a considerable influence on the macroscopic material properties. Furthermore, certain fillers can act as catalytically active sites to promote the accelerated decomposition of the polymer matrix due to elevated temperatures or under the influence of electromagnetic radiation. This can be particularly important for polymer matrices containing heteroatoms.

[0005] The problem addressed was therefore to provide a composition based on polyetheretherketone which has improved tribological and ductile properties, in particular an improved wear rate at elevated pressure and / or elevated temperature.

[0006] Surprisingly, it has now been found that hydrophobic silica, in particular hydrophobic fumed silica, in combination with carbon fibers increases the wear rate of polyetheretherketone under tribological stress at elevated temperature without any adverse effect on ductility.

[0007] The present invention provides a thermoplastic composition,

[0008] A) has a matrix component comprising polyetheretherketone, and

[0009] B) has a filler component,

[0010] It is characterized by

[0011] Relative to the total composition of the thermoplastic composition, 30% to 95% by weight of polyetheretherketone as matrix component A) is present, the polyetheretherketone comprising the polyetheretherketone structural element of the formula I

[0012]

[0013] Its MVR is 10 to 90 cm 3 / 10min, the MVR is measured at 400°C, a load of 2.16kg, and a capillary (length 8mm*diameter 2.095mm), and

[0014] In the total composition of the thermoplastic composition, there are 5 to 70% by weight of inorganic and carbonaceous particles as filler component B), which, relative to the total composition, comprises

[0015] 1 to 20% by weight of hydrophobic silica,

[0016] 1% to 20% by weight of carbon fibers,

[0017] 1 to 20% by weight of titanium dioxide particles,

[0018] 1 to 20 wt% of graphite particles, and

[0019] 1 to 20% by weight of a particulate lubricant selected from divalent metal sulfides and alkaline earth metal sulfates,

[0020] The total composition is 100 wt %,

[0021] The thermoplastic composition is useful as a component in lubricant-free tribological applications.

[0022] The present invention also provides a process for preparing the composition according to the invention, wherein the process according to the invention is carried out by mixing in an extruder, by adding at least one masterbatch containing hydrophobic silica to the base feed and adding carbon fibers downstream.

[0023] The present invention further provides for the use of the composition according to the invention for producing shaped articles and components produced therefrom for lubricant-free tribological applications.

[0024] The composition according to the present invention, the method according to the present invention and the use according to the present invention are described below by way of example, but it is not intended that the present invention be limited to these exemplary embodiments. Where ranges, general formulas or compound classes are stated below, these are intended to include not only the corresponding ranges or compound groups explicitly mentioned, but also all sub-ranges and sub-groups or compounds of the compounds that can be obtained by extracting a single value (range). When citing a document in the context of this specification, its entirety shall constitute a part of the disclosure of the present invention. Where percentage data are provided hereinafter, these data are in % by weight unless otherwise stated. In the case of a composition, the % value is based on the total composition unless otherwise stated. Where average values ​​are provided hereinafter, these are average values ​​(average values ​​by weight) by mass unless otherwise stated. Where measured values ​​are given hereinafter, these measured values ​​are measured at a pressure of 101325 Pa and a temperature of 25° C. unless otherwise stated.

[0025] The scope of protection includes the finished and packaged forms customarily used in commerce for the product of the invention, not only per se but also possible comminuted forms not defined in the claims.

[0026] One advantage of the compositions according to the invention and components produced therefrom is that the tribological properties are improved compared to the prior art. In particular, friction and wear are reduced. This demonstrates that the use of SiO particles in the compositions according to the invention is particularly advantageous.

[0027] Another advantage of the composition according to the invention is reduced friction, particularly in systems where one component consists of metal and another consists of the composition according to the invention. A further advantage is that the coefficient of friction is low even at elevated temperatures. Furthermore, the properties associated with friction generation are improved.

[0028] One advantage of the specially adapted method setup is firstly the production of a homogeneous composition and, secondly, that the carbon fibers used are shortened in a defined manner.

[0029] Tribological applications at elevated temperatures can be realized particularly advantageously with the composition according to the invention.

[0030] Furthermore, it has been found that carbon fibers of a specific fiber length, combined with hydrophobic silica particles, have an additional positive effect on the tribological properties of polyetheretherketone. The use of hydrophobized silica, in particular hydrophobized fumed silica, significantly reduces the negative influence of conventional silica particles on the melt viscosity during the preparation of thermoplastic compositions.

[0031] In order to further improve the processability of the thermoplastic composition at the high processing temperatures required for the composition according to the invention, the melt viscosity is adjusted specifically for the filler component by selecting the molecular weight of the polyetheretherketone. The composition according to the invention comprises a polyetheretherketone as a matrix component having an MVR of 10 to 90 cm 3 / 10min, preferably 15 to 80cm 3 / 10min, more preferably 20 to 75cm 3 / 10min, particularly preferably 30 to 60cm 3 / 10min, the MVR is measured at 400°C and a load of 2.16 kg with the aid of a capillary with a length of 8 mm and a diameter of 2.095 mm.

[0032] The matrix component preferably consists of polyetheretherketone.

[0033] The carbon fibers used preferably have a fiber length of 4 to 8 mm, more preferably 5 to 7 mm, and a diameter of preferably 5 to 10 micrometers (μm) and more preferably 6 to 8 μm before processing.

[0034] The composition according to the invention has been found to be advantageous because the process setup firstly enables the production of a homogeneous composition and secondly, with respect to the carbon fibers used, the carbon fibers used are shortened. It is particularly advantageous here that the shortened carbon fibers have a characteristic distribution due to the process regime.

[0035] The composition according to the invention preferably contains carbon fibers having a fiber length of 15 to 555 μm; preferably, at least 95% (based on the number of fibers) of the carbon fibers have a fiber length of 15 to 350 μm, more preferably at least 90% of the carbon fibers have a fiber length of 20 to 300 μm, particularly preferably at least 75% of the carbon fibers have a fiber length of 25 to 180 μm, and particularly preferably at least 50% of the carbon fibers have a fiber length of 30 to 110 μm.

[0036] The hydrophobic silica used in the composition according to the invention is preferably a fumed hydrophobic silica.

[0037] The person skilled in the art knows how to prepare fumed silica particles; these are preferably obtained by decomposition of halosilanes by an oxidative flame process.

[0038] Before processing, hydrophobic fumed silica has a D 50 is 2 to 5 μm, preferably 2.5 to 4 μm, and D 100 Less than 150μm, preferably D 100 Particle size distribution of less than 100 μm, determined according to ISO 13320 using dry dispersed granules.

[0039] The particle size is preferably determined in a dry gas stream according to ISO 13320, preferably with a Malvern Mastersizer 3000.

[0040] The carbon content of the hydrophobic fumed silica is 1 to 2 wt.-%, based on the silica, according to ISO 3262-20.

[0041] The hydrophobic fumed silica preferably has primary particles with a primary particle size of 10 to 30 nm.

[0042] The hydrophobic fumed silica is preferably methyl-modified.

[0043] Further preferably, the hydrophobic fumed silica comprises agglomerates of primary particles of silica with a particle size of 400 nm to 100 micrometers. When using the particle size D 50 of 2 to 20 micrometers, in particular D 90 of not more than 50 micrometers. It is further preferred here that the agglomerates have a particle size D 50 of 2 to 5 micrometers, and preferably D 90 of not more than 20 micrometers. It has been found to be particularly advantageous when the agglomerates are at least partially aggregated to form the agglomerates due to the processing conditions. Thus, the composition preferably comprises a hydrophobic fumed silica comprising agglomerates of primary particles of silica, wherein the silica has surface methyl groups.

[0044] Particularly preferred is a hydrophobic fumed silica comprising primary particles of 10 nm to 100 nm, preferably 10 nm to 30 nm, wherein the silica is particularly surface-modified with organofunctional silanes, the silica is preferably modified with alkylfunctional silanes, and the silica is more preferably methyl-modified.

[0045] The graphite particles of the composition according to the application preferably have a particle size distribution of less than 70 pm, more preferably less than 60 pm, particularly preferably less than 50 pm and especially preferably less than 40 pm. 100

[0046] The graphite particles preferably have a particle size distribution of 5 to 15 pm, preferably 8 to 12 pm, and less than 50 pm, preferably less than 40 pm. 50 100

[0047] Further preferably, the mode diameter (D mode ), i.e. the maximum of the distribution, deviates by not more than 30%, preferably 25%, from the measured value of D 50 . More preferably, D 50 is 30%, preferably 25%, smaller than D mode .​​​

[0048] More preferably, the particle size distribution of the graphite particles is D 50 5 to 15 μm, D 100 Less than 50μm, and D 50 25% smaller than the mode diameter.

[0049] The carbon content of the graphite particles is preferably not less than 99 wt%, particularly not less than 99.5 wt%, and preferably greater than 99.7 wt% to 99.99 wt%, relative to 100 wt% of the total composition of the graphite particles.

[0050] The measurement of the particle size distribution is carried out according to ISO 13320 using dry dispersed particles.

[0051] The particle size is determined according to ISO 13320, preferably using a Malvern Mastersizer 3000 in a dry air stream.

[0052] The preferred titanium dioxide particles of the composition according to the present invention have an outer shell comprising a metal oxide containing silicon, aluminum and / or zirconium or a mixed oxide containing these, wherein the titanium dioxide particles are at least partially or completely encapsulated by the above-mentioned shell. The titanium dioxide particles are preferably completely encapsulated by a mixed oxide shell containing silicon, aluminum and zirconium. The titanium dioxide particles with a preferably complete outer shell are preferably in core-shell form and are preferably prepared by a plasma process or a thermal process, wherein the outer shell comprises a metal oxide containing silicon, aluminum and / or zirconium or a mixed oxide containing these. Therefore, the titanium dioxide particles used according to the present invention are preferably titanium dioxide core-shell particles, whose core comprises titanium dioxide and whose shell consists of a metal oxide that does not have catalytic properties, especially does not have photocatalytic properties. More particularly, the titanium dioxide particles have a completely closed shell. Therefore, these titanium dioxide particles can also be referred to as core-shell particles, which have a core comprising titanium dioxide and a shell comprising a mixed oxide containing silicon, aluminum and zirconium. This prevents the titanium dioxide from forming catalytically active sites under elevated temperatures and / or elevated tribological influences, which promotes accelerated decomposition of the polymer matrix. It has been found that a disadvantage of titanium dioxide particles without an inert shell is that they can act as catalytically active sites under the influence of electromagnetic radiation, tribological stresses, and / or elevated temperatures. However, in order to be able to utilize the mechanical properties of titanium dioxide while simultaneously avoiding the adverse effects of the titanium dioxide particles, it is preferred to use specific titanium dioxide particles having a protective shell. Therefore, it is particularly preferred to use titanium dioxide particles having a shell in thermoplastic compositions, the shell comprising a silicon compound, an aluminum compound, and / or a zirconium compound, in particular their oxides. The oxides of these compounds can be present in the shell as SiO2, zirconium dioxide, Al2O3, or mixed oxides and silicate compounds of these compounds, i.e., crystalline compounds. These particles are inactivated with respect to their ability to act as catalytic sites in the polymer matrix.

[0053] The titanium dioxide particles preferably have a bimodal particle distribution.

[0054] Preferred titanium dioxide particles have a particle size of 100 nanometers (nm) to 10 micrometers, and D is particularly preferred. 50 150 to 600 nm, more preferably D 50 250 to 500nm.

[0055] The particle size distribution further preferably has a maximum value (D mode ).

[0056] Further preferably, the titanium dioxide particles preferably have a bimodal particle size distribution, wherein the second maximum is in the range of 2.5 to 6 μm, preferably in the range of 3 to 5 μm.

[0057] More preferably, the weight ratio of the two ranges of particle size of titanium dioxide particles in the bimodal distribution (range 1 contains D mode ; Range 2 contains the second maximum) is: 7:1 to 9.5:1, preferably 8:1 to 9.3:1, more preferably 9:1 (preferably assuming that the measurement accuracy of the area ratio is 3%).

[0058] The measurement of the particle size distribution is carried out according to ISO 13320 using dry dispersed particles.

[0059] The particle size is determined according to ISO 13320, preferably using a Malvern Mastersizer 3000 in a dry air stream.

[0060] The titanium dioxide particles have preferably been surface modified with Si, Zr and Al.

[0061] Further preferably, the titanium dioxide particles preferably have a bimodal particle size distribution and have been surface modified.

[0062] Further preferably, the titanium dioxide particles preferably have a bimodal particle size distribution, with a maximum value (D mode ) is 280 to 350 nm (range 1), the second maximum in range 2 is 2.5 to 6 μm, and has been surface modified with Si, Zr and Al.

[0063] The particulate lubricant of the composition according to the invention is selected from divalent metal sulfides and alkaline earth metal sulfates, preferably ZnS and / or BaSO4; the particulate lubricant is especially ZnS. Particle size distribution D of the particulate lubricant 90 It is preferably less than 20 μm, preferably not more than 15 μm, more preferably 10 μm, and particularly preferably not more than 5 μm.

[0064] In addition, the D of the granular lubricant 50 It is preferably 500 to 1000 nm, more preferably 600 to 950 nm, particularly preferably 700 to 900 nm, and especially preferably 750 to 850 nm.

[0065] Further preferably, the ZnS lubricant particles have a diameter of 500 to 1000 nm. 50 and D less than 20 μm 90 , especially D from 700 to 900 nm 50 and D not greater than 5μm 90 .

[0066] Particle size distribution measurements are performed according to ISO 13320 using wet-dispersible (water-dispersible) granules.

[0067] The particle size is determined according to ISO 13320, preferably using a Malvern Mastersizer 3000.

[0068] Extensive material testing was conducted using a thermoplastic composition comprising 60% by weight of polyetheretherketone as matrix component A) and 40% by weight of filler component B), the filler component B) comprising 10% by weight of hydrophobized SiO2, 10% by weight of graphite particles, 10% by weight of carbon fibers, 5% by weight of ZnS, and 5% by weight of TiO2, each relative to 100% by weight of the total composition of the thermoplastic composition. With this composition, it was found that, surprisingly, excellent tribological properties were achieved with polyetheretherketone having a relatively high MVR.

[0069] Preference is given to a thermoplastic composition comprising as matrix component A) 30% to 95% by weight of polyetheretherketone containing polyetheretherketone structural elements of the formula I

[0070]

[0071] Its MVR is 10 to 90 cm 3 / 10min, preferably 15 to 80cm 3 / 10min, more preferably 20 to 75cm 3 / 10min, particularly preferably 30 to 60cm 3 / 10min, the MVR is measured at 400°C, a load of 2.16kg, using a capillary with a length of 8mm and a diameter of 2.095mm, at an inlet angle of 180°, and

[0072] Filler component B) comprising

[0073] 2 to 20 wt% of hydrophobic fumed silica,

[0074] 2% to 20% by weight of carbon fibers,

[0075] 1 to 15% by weight of a particulate lubricant selected from divalent metal sulfides and alkaline earth metal sulfates,

[0076] 2 to 20 wt% of graphite particles, and

[0077] 1% to 15% by weight, based on the total composition, of titanium dioxide particles having a bimodal particle size distribution.

[0078] Particularly preferred is a thermoplastic composition comprising, as matrix component A), 30% to 90% by weight of a polyetheretherketone having a structural element of the formula I and having an MVR of 10 to 90 cm 3 / 10min, particularly preferably 15 to 80cm 3 / 10min, more preferably 20 to 75cm 3 / 10min, particularly preferably 30 to 60cm 3 / 10min, the MVR is measured at 400°C, a load of 2.16kg, using a capillary with a length of 8mm and a diameter of 2.095mm, at an inlet angle of 180°.

[0079] and includes

[0080] 5 to 15 wt% of a hydrophobic fumed silica having a D 50 is 2 to 5 μm, preferably 2.5 to 4 μm, and D 100 Less than 150μm, preferably D 100 Particle size distribution less than 100 μm,

[0081] 2 wt% to 8 wt% of ZnS as a particulate lubricant, the particle size D 50 500 to 1000 nm, preferably 600 to 950 nm, more preferably 700 to 900 nm, particularly preferably 750 to 850 nm,

[0082] 5% to 15% by weight of graphite particles,

[0083] 2 to 8 wt% of titanium dioxide particles having a bimodal particle size distribution and which have been surface-modified with Si, Zr and Al, and

[0084] 5 to 15% by weight of carbon fibers,

[0085] Based on 100% by weight of the total composition of the thermoplastic composition.

[0086] Particularly preferred thermoplastic compositions consist of:

[0087] 30% to 81% by weight of polyetheretherketone having an MVR of 10 to 90 cm 3 / 10min, particularly preferably 15 to 80cm 3 / 10min, more preferably 20 to 75cm 3 / 10min, particularly preferably 30 to 60cm 3 / 10min,

[0088] 2 wt% to 8 wt% ZnS as a particulate lubricant having D 50 500 to 1000nm, D 90 Less than 20μm, especially D 50 700 to 900 nm, D 90 Particle size distribution not greater than 5 μm,

[0089] 5 to 15% by weight of graphite with a particle size of 0.5 to 30 μm, preferably 5 to 20 μm, more preferably 5 to 15 μm, particularly preferably 8 to 12 μm,

[0090] 2 to 8 wt% titanium dioxide particles having a bimodal particle size distribution with a maximum (D mode ) is 280 to 350 nm (range 1), the second maximum in range 2 is 2.5 to 6 μm, and has additionally been surface-modified with Si, Zr and Al,

[0091] 5 to 15 wt% of a hydrophobic fumed silica having a D 50 is 2 to 5 μm, preferably 2.5 to 4 μm, and D 100 Less than 150μm, preferably D 100 Particle size distribution of less than 100 μm, and

[0092] 5 to 15% by weight of chopped carbon fibers with a diameter of 5 to 10 μm, preferably 6 to 8 μm, and a fiber length of 15 to 555 μm,

[0093] Based on 100% by weight of the total composition of the thermoplastic composition.

[0094] Particularly preferred thermoplastic compositions consist of:

[0095] 30% to 73.5% by weight of polyetheretherketone having an MVR of 10 to 90 cm 3 / 10min, particularly preferably 15 to 80cm 3 / 10min, more preferably 20 to 75cm 3 / 10min, particularly preferably 30 to 60cm 3 / 10min,

[0096] 7.5% to 12.5% ​​by weight of hydrophobic fumed silica, based on silicon dioxide, having a carbon content of 1% to 2% by weight according to ISO 3262-20, with D 50 is 2.5 to 4 μm, and D 100 Particle size distribution less than 100 μm,

[0097] 2 wt% to 8 wt% ZnS as a particulate lubricant having D 50 700 to 900 nm, D 90 Particle size distribution not exceeding 5 μm,

[0098] 7.5 wt% to 12.5 wt% graphite particles having a D 50 is 5 to 15 μm, preferably 8 to 12 μm, and D 100 a particle size distribution of less than 50 μm, preferably less than 40 μm,

[0099] 2% to 8% by weight of titanium dioxide particles having a bimodal particle size distribution with a maximum value (D mode ) is from 280 to 350 nm (range 1), and the second maximum in range 2 is from 2.5 to 6 μm, wherein the weight ratio of the two ranges is from 7:1 to 9.5:1, preferably from 8:1 to 9.3:1, more preferably 9:1, and the particles have additionally been surface-modified with Si, Zr and Al, and

[0100] 7.5 to 12.5% ​​by weight of carbon fibers having a diameter of 6 to 8 μm, of which at least 90% of the carbon fibers have a fiber length of 20 to 300 μm, more preferably at least 75% of the carbon fibers have a fiber length of 25 to 180 μm, particularly preferably at least 50% of the carbon fibers have a fiber length of 30 to 110 μm,

[0101] Based on 100% by weight of the total composition of the thermoplastic composition.

[0102] The present invention further provides a process for preparing a thermoplastic composition and a composition obtainable by this process, wherein the process comprises at least step i), wherein

[0103] i) preparing a first masterbatch by mixing the following components at elevated temperature, preferably close to the melting point of polyetheretherketone or higher, preferably at 350° C. to 500° C., in an extruder, preferably in a twin-screw extruder, more preferably in a co-rotating twin-screw extruder having a dispersion zone and a mixing zone,

[0104] 40% to 95% by weight, preferably 60% to 90% by weight, of a polyetheretherketone comprising structural units of the formula I and having an MVR of 10 to 90 cm 3 / 10 min, especially preferably 15 to 80 cm 3 / 10 min, more preferably 20 to 75 cm 3 / 10 min, especially preferably 30 to 60 cm 3 / 10 min, the MVR being determined at 400 °C, under a load of 2.16 kg, with a capillary having a length of 8 mm and a diameter of 2.095 mm, at an entry angle of 180°, and with

[0105] 5 to 60 wt.-%, preferably 10 to 40 wt.-%, of a hydrophobic silica, in particular a hydrophobic fumed silica, to obtain a first masterbatch,

[0106] wherein the first masterbatch is produced at a vacuum pressure of 1000 to 5 mbar, preferably 800 to 10 mbar, more preferably 500 to 50 mbar, and especially preferably 300 to 100 mbar, each absolute pressure;

[0107] wherein the first masterbatch is fed into the base feed and downstream carbon fibers are fed to obtain the thermoplastic composition.

[0108] According to a preferred process of the present application, in addition to the process step i) described above, there is a further process step ii), wherein

[0109] ii) producing a second masterbatch by mixing the following components in an extruder, preferably in a twin-screw extruder, more preferably in a co-rotating twin-screw extruder having a dispersion zone and a mixing zone, at elevated temperature, preferably close to the melting point of the polyether ether ketone or higher, preferably at 350 °C to 500 °C,

[0110] 30 to 90 wt.-%, preferably 50 to 80 wt.-%, of a polyether ether ketone comprising structural elements of formula I, having a MVR of 10 to 90 cm 3 / 10 min, at 400 °C, under a load of 2.16 kg, with a capillary having a length of 8 mm and a diameter of 2.095 mm, at an entry angle of 180°, and with

[0111] 5 to 40 wt.-%, preferably 10 to 30 wt.-%, of titanium dioxide particles and 5 to 40 wt.-%, preferably 10 to 30 wt.-%, of a particulate lubricant selected from the group consisting of divalent metal sulfides and alkaline earth metal sulfates, to obtain a second masterbatch,

[0112] wherein the first masterbatch and the second masterbatch are fed into the base feed and downstream carbon fibers are fed to obtain the thermoplastic composition.

[0113] According to a particularly preferred process of the present application, in addition to the process steps i) and ii) described above, there is a further process step iii), wherein

[0114] iii) preparing the composition by mixing at elevated temperature, preferably close to the melting point of the polyetheretherketone or above, preferably at 350° C. to 550° C., in an extruder, preferably in a twin-screw extruder, more preferably in a co-rotating twin-screw extruder having a dispersion zone and a mixing zone, a mixture comprising

[0115] 0% to 70% by weight, preferably 1% to 50% by weight, more preferably 2% to 20% by weight, particularly preferably 3% to 10% by weight of a polyetheretherketone having a structural element of formula I and having an MVR of 10 to 90 cm 3 / 10min, at 400℃, load 2.16kg, using a capillary with a length of 8mm and a diameter of 2.095mm, measured at an inlet angle of 180°,

[0116] The first masterbatch, and

[0117] Second masterbatch,

[0118] wherein downstream, preferably at 350° C. to 550° C., graphite particles and carbon fibers are successively added to the mixture and mixed therewith,

[0119] A thermoplastic composition is obtained.

[0120] Fillers in the composition according to the invention which are not listed in the process steps may already be present in the base charge or may be added later; preferably no fillers are added after the addition of the carbon fibers.

[0121] The weight % data in the above method steps are based on the total composition of the first masterbatch in step i) being 100 weight %, the total composition of the second masterbatch in step ii) being 100 weight %, and the total composition of the combination in step iii) being 100 weight %.

[0122] The weight ratio of the first masterbatch to the second masterbatch, preferably the weight ratio in process step iii), is preferably set at 0.1 (1:10) to 10 (10:1), preferably 0.5 to 5, more preferably 1 to 3.

[0123] The first and second masterbatches are preferably prepared in an extruder at 380° C. to 450° C. The thermoplastic composition is preferably also prepared in an extruder at 380° C. to 450° C.

[0124] It is preferred to use carbon fibers having a fiber length of 4 to 8 mm, more preferably 5 to 7 mm, and a diameter of preferably 5 to 10 micrometers (μm), more preferably 6 to 8 μm.

[0125] After step iii), in the process according to the invention, the thermoplastic composition can be cooled and processed, preferably pelletized, or directly produced into shaped articles and then cooled.

[0126] The above-mentioned preferences for the filler components also apply correspondingly to the method according to the invention.

[0127] The thermoplastic composition according to the invention and the thermoplastic composition obtainable by the process according to the invention are used for producing three-dimensionally shaped articles.

[0128] The invention also provides components comprising the thermoplastic composition, such as preferably semi-finished products, profiles, filaments and films, wherein the production of shaped articles is familiar to the person skilled in the art. These can be obtained in the following process

[0129] a) injection molding methods including single-component to multi-component injection molding methods,

[0130] b) Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF),

[0131] c) pressing method,

[0132] d) extrusion processes, including coextrusion processes, optionally with calendering or e.g. blown film, and / or

[0133] e) During material removal.

[0134] The resulting shaped articles, semi-finished products, and profiles can be further processed and bonded using conventional joining methods for thermoplastics, such as radiation, vibration, heating element, or ultrasonic welding or bonding. The present invention also provides components, in particular monolithic components, made from the thermoplastic composition. Granulated material is understood to mean, in particular, granulated material of small particle size (powder) that can be used for injection molding, extrusion, or pressing methods and / or for powder-based methods such as laser sintering. For example, metal components can also be coated with the thermoplastic composition.

[0135] The granulated material preferably has a particle size in the range of 0.5 to 10 mm and has circular, oval or angular cross sections, preferably a nearly cylindrical shape.

[0136] The shaped articles according to the invention are used for producing components for tribological applications, preferably as machine elements such as bearings or gears and parts thereof.

[0137] Thermoplastic compositions are preferably used as so-called tribological compounds, since they have shown to be particularly suitable for parts, assemblies and machine elements subject to high tribological stresses, such as radial or axial bearings (sliding bearings) having a layer of the thermoplastic composition at least in the friction surface.

[0138] Bearings or other shaped articles according to the present invention can be provided with a thermoplastic composition only very thinly, for example, in the friction zone. For example, a thin friction layer of a thermoplastic composition can be applied to a steel sleeve / steel belt (e.g., as a foil) or other friction layer. Furthermore, parts or assemblies with a friction layer can be composed of a thermoplastic composition as a single part. Furthermore, hybrid structures (multi-component parts or composite parts) can be produced from different plastics: for example, a tribological compound plus a supporting layer of an alternative plastic and / or additional regions of other materials. Furthermore, in addition to the thermoplastic composition according to the present invention, hybrid assemblies or hybrid constructions (multi-component parts) can include further different polymer components and / or metal-based materials. Furthermore, hybrid plain bearings with a metal supporting region and thinner regions of thermoplastic composition can be used.

[0139] Likewise easily achievable is a combination with foamed plastic regions in lightweight construction and in applications with reduced moving mass. Also possible is a combination with fiber-reinforced polymer-based composite materials, such as adhesive tapes or organic sheets.

[0140] In summary, composite parts can be obtained which comprise or consist of a thermoplastic composition according to the invention and a tribologically non-optimized polymer composition and / or other material.

[0141] The thermoplastic composition according to the invention is suitable in principle for producing or as part of all components subject to tribological stress, such as bearings, guideways, rolling elements, optionally present gears, etc. These components can be produced entirely or only partially (in the sliding area) from the thermoplastic composition. The thermoplastic composition can also be used in applications where the components are subject to dry friction, for example plastic-on-plastic or plastic-on-metal, as in the case of steel shafts.

[0142] In the equivalent field of the present invention are equivalent compositions and shaped articles and components thereof for use with lubricants such as oils and greases.

[0143] One advantage of the use according to the invention is the wear of metal surfaces. For example, depending on the selected test conditions, such as the alloy selected, the surface roughness of the metal friction component, the load conditions resulting from the relative speed in the cross-sectional area, pressure, and temperature, it has been shown, for example, in block-on-ring tests, that the wear rate of components made of thermoplastic compositions can be significantly reduced and very low coefficients of friction can be observed.

[0144] Figure 1 shows the coefficient of friction of Inventive Example 1 and the commercial material WG101 from Victrex (Comparative Example 2) in a rising load test at a pressure of 4 MPa with increasing speed. Details of the rise are given in the descriptive notes in Table 2. The lower coefficient of friction of the shaped article according to the present invention is evident.

[0145] Particularly advantageously, components made from the composition according to the invention do not cause any adaptation problems after speed changes. Friction quickly stabilizes at a new constant value and, importantly, does not fluctuate, i.e., exhibit transient behavior. This is particularly advantageous because changes in operating speed, i.e., rotational speed, such as in concentric rotor bearings, do not cause any additional stress in other components, i.e., large jumps in torque affecting the axis of the concentric bearing.

[0146] Material:

[0147] PEEK: Polyetheretherketone from Evonik with different MVRs.

[0148] SiO2: hydrophobized fumed silica, carbon content 1.2 wt% (ISO 3262-20); particle size (dry dispersion) D 50 3.13μm, D 100 <80μm.

[0149] ZnS: Particle size (wet dispersion) D 50 0.80μm, D 90 <5μm.

[0150] Carbon fiber: Sigrafil C C6-4.0 / 240-T190.

[0151] Graphite particles: particle size (dry dispersion) D 50 9.3μm, D 100 <35μm.

[0152] TiO2: particle size (dry dispersion) D (mode, maximum) 350 nm, D (double peak, maximum) 3.5 μm; surface modified with Si, Zr and Al.

[0153] Example 1: Based on MVR of 34 cm 3 / 10min (test weight 2.16kg / 400℃) PEEK composition

[0154] Example 2: Based on MVR of 72 cm 3 / 10min (test weight 2.16kg / 400℃) PEEK composition

[0155] Preparation of thermoplastic composition in a twin-screw extruder:

[0156] Masterbatch 1: 80 wt% PEEK and 20 wt% SiO2, extruded (melt temperature 439°C, shell temperature 390°C), devolatilized using a vacuum pressure of about 300 to 100 mbar absolute (at the point of silica addition).

[0157] Masterbatch 2: 60 wt% PEEK, 20 wt% TiO2 and 20 wt% zinc sulfide (melt temperature 428°C, shell temperature 390°C).

[0158] 50 wt% of masterbatch 1 and 25 wt% of masterbatch 2 were added to the extruder's base feed (5 wt% of each PEEK). 10 wt% of graphite and 10 wt% of carbon fiber were added downstream. The melt temperature was 439°C and the shell temperature was 390°C. The product was pelletized at the end of extrusion.

[0159] Thus, the composition according to the invention from the examples contains 60% by weight of PEEK, 10% by weight of SiO 2 particles, 5% by weight of ZnS particles, 10% by weight of graphite particles, 5% by weight of TiO 2 particles and 10% by weight of carbon fibers.

[0160] The comparative example (Comparative Example 1) contained 60% by weight of PEEK (VESTAKEEP2000, a product from Evonik), 10% by weight of ZnS particles, 10% by weight of graphite particles, 10% by weight of TiO2 particles and 10% by weight of carbon fibers.

[0161] Another comparative example (Comparative Example 2) is the commercial product WG101 from Victrex.

[0162] Test specimens: The pellets were injection molded into plaques; the dimensions of the plaques were 4 mm thick and 50 mm x 50 mm in area.

[0163] The specimens were processed into cubes. Their test area was 4×4 mm 2 , with a length of 10 mm. The fibers are essentially aligned in the test plane; the friction force vector and the fiber alignment vector are orthogonal to each other.

[0164] To determine the tribological properties, block-on-ring and pin-on-disc tests were performed; the specimens had identical dimensions:

[0165] The measurements were carried out at different speeds (v = 0.5 m / s, 1 m / s, 2 m / s, 3 m / s, and 4 m / s) and at different contact pressures (pressure loads) (p = 1 MPa, 2 MPa, 4 MPa, 8 MPa, and 10 MPa). After the running-in phase, the test phase began. The test blocks were made of the test material; the rings and disks were made of steel (100Cr6H). The wear rate was measured by determining the mass loss. The measurements were carried out without lubricant and at different temperatures.

[0166] The friction coefficient (COF, friction value) and wear rate Ws[10 -6 mm 3 / Nm]. The calculation of wear rate is based on the mass loss of the specimen, according to the formula: W s =(Δm) / ρνtF n , where Δm is the mass loss, ρ is the density of the test material, ν is the sliding velocity, and t is the test duration. n is the contact force of the specimen.

[0167] The values ​​in Tables 1a to 1d were obtained on a ring-on-ring test bench at 23°C. The running-in phase lasted 2 hours, and the test phase lasted 20 hours. The steel rings had a roughness depth (Rz) of 2 μm and an arithmetic mean roughness (roughness, Ra) of 0.2 μm.

[0168] Table 1a: Friction coefficient versus sliding speed at a contact pressure of 1 MPa, 23°C

[0169]

[0170] The friction coefficients of Examples 1 and 2 of the present invention are lower than that of the commercially available Victrex WG101 product. Furthermore, the friction coefficients of Examples 1 and 2 of the present invention decrease significantly with increasing sliding speed, while the friction coefficient of Comparative Example 2 actually increases from 0.5 m / s to 2 m / s.

[0171] Table 1b: Friction coefficient versus sliding speed at 2 MPa contact pressure, 23°C

[0172]

[0173] With increasing speed and increasing contact pressure of 2 MPa, the low friction coefficients of Examples 1 and 2 of the present invention further decrease.

[0174] Table 1c: Relationship between friction coefficient and sliding speed at contact pressure of 4 MPa

[0175]

[0176] Even at a further increased contact pressure of 4 MPa, the friction coefficient of inventive example 2 continues to decrease further with increasing speed. For the composition of example 1, a minimum friction coefficient is found at a speed of 2 m / s.

[0177] Table 1d: Relationship between friction coefficient and sliding speed at contact pressure of 8 MPa

[0178]

[0179] The friction coefficient of Example 1 of the present invention is lower than the friction coefficient of Example 2. At a further increased contact pressure of 8 MPa, both friction coefficients continue to decrease further with increasing speed.

[0180] Example 1 has similarly good coefficients of friction at 8 MPa and 2 MPa.

[0181] The values ​​in Table 2 refer to the rising load test; they were found at a temperature of 23°C on the block-on-ring test rig. Without a running-in phase, the sliding speeds were initially 0.5 m / s (10 h), 1 m / s (7.5 h), 2 m / s (5 h), 3 m / s (5 h), and then gradually increased to 4 m / s (2.5 h). The roughness depth (Rz) of the steel rings was 2 μm, and the arithmetic mean roughness (roughness, Ra) was 0.2 μm.

[0182] Table 2: Relationship between wear rate and contact pressure when speed increases from 0.5m / s to 4m / s

[0183]

[0184] The wear rates of Examples 1 and 2 of the present invention are lower than the wear rate of Victrex WG 101. In addition, the wear rate of Example 1 of the present invention decreases significantly and continuously as the contact pressure increases.

[0185] FIG1 shows a rising load test of the samples of Example 1 and Comparative Example 2 under a contact pressure of 4 MPa; the measurement of the friction coefficient was carried out at 20° C.

[0186] The values ​​in Tables 3a and 3b were obtained on a pin-on-disc test bench at 23°C and 100°C. The test period was 5000 m. The steel ring had a roughness depth (Rz) of 5 μm and an arithmetic mean roughness (roughness Ra) of 0.4 μm.

[0187] Table 3a: Pin-to-disc wear rate at 1 m / s

[0188]

[0189] Table 3b: Pin-to-disc sliding friction coefficient at 1 m / s

[0190]

[0191] At elevated contact pressures, and even with increasing temperature, the wear rate and coefficient of friction of the embodiments of the present invention are significantly reduced.

[0192] The values ​​in Tables 4a, 4b, 5a and 5b were obtained on a block-on-ring test bench at 25° C. The arithmetic mean roughness (roughness Ra) of the steel rings was 0.1 μm to 0.2 μm.

[0193] Table 4a: Wear rates compared to the material of the KS sliding bearing (EP1511625B2, sample PEEK6)

[0194]

[0195] These tests also clearly demonstrate that components made from the composition according to the invention outperform the prior art. More specifically, these tests demonstrate the advantageous use of SiO particles in tribological applications. In these tests, this is particularly evident under high load pressures or high speeds.

[0196] Table 5a: Wear rate versus pressure load and velocity quotient (p / v [MPa*s / m]), block to ring

[0197]

[0198] Table 5b: Friction coefficient versus pressure load and velocity quotient (p / v [MPa*s / m]), block-to-ring

[0199]

[0200] The wear rate and friction coefficient are generally lower than those of the prior art. This also clearly shows the beneficial effect of adding SiO2 particles to the polymer components of the tribological system.

Claims

1. A thermoplastic composition comprising: A) has a matrix component comprising polyetheretherketone, and B) has a filler component, It is characterized by Relative to the total composition of the thermoplastic composition, 30% to 95% by weight of polyetheretherketone as matrix component A) is present, the polyetheretherketone comprising the polyetheretherketone structural element of the formula I Its MVR is 10 to 90 cm 3 / 10min, the MVR is measured at 400°C, a load of 2.16kg, using a capillary with a length of 8mm and a diameter of 2.095mm, at an inlet angle of 180°, and In the total composition of the thermoplastic composition, there are 5 to 70% by weight of inorganic and carbonaceous particles as filler component B), which, relative to the total composition, comprises 1 to 20 wt% of hydrophobic fumed silica, 1 to 20% by weight of carbon fibers, 1 to 20% by weight of titanium dioxide particles, 1 to 20 wt% of graphite particles, and 1 to 20% by weight of a particulate lubricant selected from divalent metal sulfides and alkaline earth metal sulfates, The total composition is 100 wt %, The thermoplastic composition is useful as a component in lubricant-free tribological applications.

2. The composition according to claim 1, characterized in that The overall composition of the thermoplastic composition comprises the following substances as filler components: 2 to 20 wt% of hydrophobic fumed silica, 2% to 20% by weight of carbon fibers, 1 to 15% by weight of a particulate lubricant selected from divalent metal sulfides and alkaline earth metal sulfates, 2 to 20 wt% of graphite particles, and 1% to 15% by weight of titanium dioxide particles, The total composition of the thermoplastic composition is 100 wt%.

3. The composition according to claim 1 or 2, characterized in that The composition comprises 30% to 81% by weight of a polyetheretherketone containing a structural element of formula I, 5 to 15 wt% of hydrophobic fumed silica, 2 to 8 wt. % of a particulate lubricant selected from divalent metal sulfides and alkaline earth metal sulfates, 5 to 15% by weight of graphite particles, 2% to 8% by weight of titanium dioxide particles, and 5% to 15% by weight of carbon fibers, The total composition of the thermoplastic composition is 100 wt%.

4. The composition according to claim 1 or 2, characterized in that The composition comprises 30% to 73.5% by weight of a polyetheretherketone containing a structural element of formula I, 7.5 to 12.5 wt% of hydrophobic fumed silica, 2 to 8 wt. % of a particulate lubricant selected from divalent metal sulfides and alkaline earth metal sulfates, 7.5 to 12.5% ​​by weight of graphite particles, 2% to 8% by weight of titanium dioxide particles, and 7.5 wt% to 12.3 wt% carbon fibers, wherein the total composition of the thermoplastic composition is 100 wt%.

5. The composition according to claim 1 or 2, characterized in that The fiber length of the carbon fibers is 15 to 555 μm.

6. The composition according to claim 5, characterized in that At least 50% of the carbon fibers have a fiber length of 30 to 110 microns.

7. The composition according to claim 1 or 2, characterized in that The hydrophobic fumed silica has D 50 2 to 5 μm, and D 100 Particle size distribution of less than 150 μm, determined according to ISO 13320 using dry dispersed granules.

8. The composition according to claim 7, characterized in that The hydrophobic fumed silica has D 50 The particle size distribution is 2.5 to 4 μm.

9. The composition according to claim 7, characterized in that The hydrophobic fumed silica has D 100 Particle size distribution less than 100 μm.

10. The composition according to claim 1 or 2, characterized in that The carbon content of the hydrophobic fumed silica is 1 to 2 wt % based on the hydrophobic fumed silica according to ISO 3262-20.

11. The composition according to claim 1 or 2, characterized in that The titanium dioxide particles have a bimodal particle size distribution.

12. The composition according to claim 1 or 2, characterized in that The graphite particles have D 50 5 to 15 μm, and D 100 Particle size distribution of less than 50 μm, determined according to ISO 13320 using dry dispersed granules.

13. The composition according to claim 12, characterized in that The graphite particles have D 50 The particle size distribution is 8 to 12 μm.

14. The composition according to claim 12, characterized in that The graphite particles have D 100 Particle size distribution less than 40 μm.

15. The composition according to claim 1 or 2, characterized in that The particulate lubricant is ZnS and has D 50 500 to 1000 nm and D 90 Particle size distribution less than 20 μm.

16. Process for preparing a thermoplastic composition according to any one of claims 1 to 15, wherein the process comprises at least one step i) wherein i) preparing a first masterbatch by mixing a polyetheretherketone containing a structural element of formula I with hydrophobic fumed silica in an extruder at elevated temperature and wherein the first masterbatch is prepared under a vacuum pressure of 1000 to 5 mbar absolute pressure, and the first masterbatch is obtained; The first masterbatch is fed into a base feed, and carbon fibers are fed downstream to obtain the thermoplastic composition.

17. The method according to claim 16, characterized in that The first masterbatch is prepared under a vacuum pressure of 300 to 100 mbar absolute.

18. The method according to claim 16 or 17, characterized in that i) the first masterbatch is prepared at 380°C to 450°C, and / or ii) the second masterbatch is prepared at 380°C to 450°C, and / or iii) The thermoplastic composition is prepared at 380°C to 450°C.

19. The method according to claim 18, characterized in that A first masterbatch was prepared in an extruder.

20. The method according to claim 18, wherein The first masterbatch was prepared in a co-rotating twin-screw extruder.

21. The method according to claim 18, wherein A second masterbatch was prepared in an extruder.

22. The method according to claim 18, wherein The second masterbatch was prepared in a co-rotating twin-screw extruder.

23. A method for preparing a granulated material, comprising The method according to any one of claims 16 to 22, wherein the thermoplastic composition is prepared in an extruder, and The material is discharged from the extruder at the extruder die, shaped, optionally removed and cooled.

24. The method of claim 23, comprising preparing the thermoplastic composition in a twin-screw extruder.

25. The method of claim 23, comprising preparing the thermoplastic composition in a co-rotating twin-screw extruder.

26. Granulated material prepared according to the method of any one of claims 23 to 25.

27. A method for preparing a shaped article, comprising The granulated material according to claim 26 is subjected to a) injection molding methods including single-component to multi-component injection molding methods, b) Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF), c) pressing method, d) extrusion processes, including coextrusion processes, optionally with calendering or film blowing, and / or e) Material removal process.

28. Shaped article obtainable by the process according to claim 27.

29. Use of the shaped article according to claim 28 as a component in lubricant-free tribological applications.

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