DE102013216652A1 - SURFACES WITH OIL-PTFE LUBRICANT AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Abstract

The invention relates to the field of chemistry and relates to surfaces with oil-PTFE lubricant, as used for example in mechanical engineering. Object of the present invention is to provide surfaces with oil PTFE lubricant, which are stable and long-term effective interconnected. The object is achieved by surfaces with oil PTFE lubricant, in which PTFE particles via -COF and / or -COOH groups and radically coupled phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane groups are chemically coupled after a reactive reaction under mechanical stress with the surface via coordinative bonds and / or ionic bonds. The object is further achieved by a process in which modified PTFE particles with -COF and -COOH groups and perfluoroalkyl (peroxy) radicals in an oil or an oil mixture with <10% by weight of organic olefinically unsaturated phosphite. and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds are dispersed under mechanical stress and subsequently contacted with the surface.

Description

The invention relates to the field of chemistry and relates to surfaces with oil PTFE lubricant, such as those used in mechanical engineering, in vehicle technology, in aerospace and as a high performance lubricant in moving parts and ropes with tribological requirements for lowering of sliding friction and wear, such. B. in transmissions (control gear, transmission for power transmission), cables (as rope lubricant), bearings (ball bearings, Wälzkörperlager, plain bearings, sliding layers and slideways), piston machines, etc. can be used.

Oil-PTFE dispersions without stabilization by additives or surfactants are made DE 10 2007 055 927 A1 and DE 10 2011 083 076 A1 known. Thereafter, stable oil-PTFE dispersions are known in which by a reactive reaction oil molecules are coupled to the PTFE via covalent bonds and the PTFE particles are negatively charged. Although in these dispersions, the PTFE particles have no particular, pronounced chemical affinity for substrate surfaces, so that the interaction occurs primarily physically via van der Waals interactions, but the van der Waals interactions are electrostatically influenced by electrostatic interactions negatively charged PTFE particles in the dispersion to a (preferably grounded metal) substrate reinforced. As a result, these oil-PTFE dispersions have improved lubricant properties through additional electrostatic interactions, which is reflected in the higher Brugger values. In DE 10 2007 055 927 A1 and DE 10 2011 083 076 A1 In addition to the increased interaction of the PTFE particles with the substrate surface by electrostatic charges, a fixation of the PTFE on the substrate surface by ionic bonds / salt bonds is described for the first time. These ionic bonds are said to be generated by reaction of the functional groups -COF and / or -COOH, which are known to be generated in the radiation modification of PTFE in the presence of (air) oxygen, with a metal substrate surface, which have proven to be advantageous in various tribological applications , The PTFE particles thus undergo enhanced interactions with a substrate surface through charging, which are further enhanced by salt bonding through reaction / coupling of the functional groups on the PTFE particle surface with the metal or metal oxide layer on the substrate surface.

The reactive coupling and thus surface modification of PTFE micropowder particles with olefinically unsaturated monomers is already out DE 103 51 812 A1 . DE 10351 813 A1 and DE 102004016876 A1 known. It is also generally known that olefinically unsaturated oils / oleyl compounds such as olive, sunflower, rapeseed or even trimethylololeate oils can not be counted among the polymerizable monomers or oligomers and can not be used since the allylic double bonds of the olefinically unsaturated oils in the sense of polymer chemistry are not free-radically or ionically polymerizable, ie, in contrast to the known coupling / grafting of PTFE with monomers, a graft (co-) polymerization is not feasible with oils. Unstabilized, olefinically unsaturated oils oxidatively, ie in the presence of oxygen, although slow resinification, but are not used as a monomer or comonomer in (radical) polymerization processes.

A disadvantage of the known solutions of the prior art is that the PTFE particles in the oil-PTFE dispersions in addition to the electrostatic charge have too little interaction with a (metal) substrate surface and thus still have insufficient lubricant properties.

The object of the present invention is to provide surfaces with oil-PTFE lubricant, which are stable and long-term effective and have improved Gleitreibungs- and wear properties of the surfaces, and a simple and inexpensive method for producing such surfaces with oil PTFE lubricants.

The object is achieved by the invention specified in the claims. Advantageous embodiments are the subject of the dependent claims.

In the case of the surfaces according to the invention with oil-PTFE lubricant, PTFE particles are above -COF and / or -COOH groups and via free-radically coupled phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate - And / or silane groups after a reactive reaction under mechanical stress with the surface via coordinate bonds and / or ionic bonds chemically coupled before.

Advantageously, PTFE particles are chemically coupled via phosphite and / or phosphate and / or sulfonate and / or silane groups.

Likewise advantageously, the silane groups present are halogen-silane and / or alkoxy-silane groups chemically coupled with the PTFE particles.

In the process according to the invention for the production of surfaces with oil-PTFE lubricant are modified PTFE particles with -COF and -COOH groups and perfluoroalkyl (peroxy) radicals in an oil or an oil mixture with <10 wt .-%, based on the amount of PTFE particles in the oil or oil mixture, organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds dispersed under mechanical stress and subsequently contacted with the surface.

Advantageously, the PTFE particles are radiation-chemically or plasma-chemically modified.

Also advantageously, the PTFE particles are modified under the influence of oxygen radiation chemistry or plasma-chemically.

Further advantageously, as oils or oil mixtures, mineral oil (s) and / or polyalphaolefin oil (s) and / or ester oil (s) and / or silicone oil (s) are used.

And also advantageously oils or oil mixtures with a concentration of olefinically unsaturated double bonds of <5% by weight, preferably oils or oil mixtures without olefinically unsaturated double bonds are used as oils or oil mixtures.

It is also advantageous if <5% by weight, advantageously <2% by weight, based on the amount of PTFE particles in the oil or oil mixture, of organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds.

It is likewise advantageous if, as organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds, dioleyl hydrogen phosphite, diethyl oleylphosphonate, diethyl allylphosphonate, oleyl dihydrogen phosphate and / or dioleyl hydrogen phosphate, Allyl phenyl dihydrogen phosphate and / or bis-2-allyl phenyl hydrogen phosphate, 2-oleylamidoethanesulfonic acid, oleyl sulfate, vinylmethyldichlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, oleylamidopropyltriethoxysilane, allyloxypropyltriethoxysilane.

Furthermore, it is advantageous if the mechanical stress is achieved by shearing, for example by stirring, kneading or ultrasound.

And it is also advantageous if in an oil or an oil mixture with <5% by weight, based on the amount of PTFE particles in the oil or oil mixture, of organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds under mechanical stress dispersed modified PTFE particles with -COF and -COOH groups and perfluoroalkyl (peroxy) radicals and coupled via radical reactions organic phosphite and / or or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds are applied to a surface of metal, plastic, glass or ceramic by means of spraying, dipping, knife coating.

With the solution according to the invention, it becomes possible for the first time to specify surfaces with oil-PTFE lubricants which are connected to each other in a stable and long-lasting manner, the surfaces thus coated having improved sliding friction and wear properties. This is made possible by a simple and inexpensive process.

The surfaces according to the invention with oil-PTFE lubricant achieve the advantageous properties by the PTFE particles having over -COF and / or -COOH groups and after a reactive reaction under mechanical stress via radically coupled phosphite and / or Phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane groups are chemically coupled to the surface via coordinate bonds and / or ionic bonds.

According to the invention, in addition to the chemical coupling by -COF and / or -COOH groups, which are coupled to the PTFE particles, to the surface and a chemical coupling by the radically coupled to the PTFE particles phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane groups, realized with advantageously halogen and / or alkoxy-silane groups as silane groups to the surface via coordinative bonds and / or ionic bonds.

The phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane groups chemically coupled to the PTFE via radical reactions, with advantageously halogen and / or alkoxy-silane groups as the silane Groups are referred to below as coupling groups.

Coordinative bonds in the context of the present invention are bonds which are an intermediate between very strong ones Represent interactions and covalent bonds and / or ionic bonds. Coordinative bonding occurs when lone pairs of electrons interact with unoccupied orbitals, that is, attach to free orbitals of a molecule or atom or ion. According to the invention this is done, for example, in the interaction of a lone pair of a coupling group with an unoccupied orbital and / or lone pairs of coupling groups with unoccupied orbitals of example transition metal atoms or transition metal ions on the (substrate) surface, for example a metal or a metal alloy, for example of transition metal (s) such as iron, cobalt, nickel, chromium, etc., or containing, and of which complex chemistry is known to be prone to complex formation. There are no complexes in the sense of complex chemistry, but the addition represents mutatis mutandis a single first stage of complex formation - namely the addition of a ligand to a (transition metal) central atom, for example on a metal substrate surface.

Coordinative bonds are known from complex chemistry based on the Lewis acid-base theory. In contrast to covalent bonds, ligands bound by coordinative bonds are interchangeable. Since the coordinative bonding takes place in the system according to the invention on a solid surface, no complexes in the sense of complex chemistry can form, but the addition is analogous to the mechanisms of complex chemistry.

According to Wikipedia, "coordinative bonding" is defined as follows: "A coordinative bond (also ... donor-acceptor bond ...) ... is a technical term for complex chemistry. Such a bond exists if, in an electron-pair bond, the binding electrons originate from only one of the two binding partners. In this case, the molecule or ion with an electron deficiency is called acceptor (= Lewis acid), that with the free electrons as donor (= Lewis base). In old textbooks, this binding is sometimes still marked by an arrow in the direction of the acceptor. These representations are outdated. A coordinative bond is drawn as a line like any other covalent bond ... "

The complex chemistry is described after Wikipedia as "... an area of Inorganic Chemistry. The term coordination chemistry is generally used synonymously. The complex chemistry deals with complexes or coordination compounds, which are composed of one or more central particles and one or more ligands. The central particles are usually atoms of transition metals, which may be charged or uncharged. In contrast to conventional covalent bonds, in complexes, usually the ligands will drive all the electrons to bond instead of each reactant contributing one electron at a time to electron-pairing; Nevertheless, there are complexes of a more covalent nature. The formation of complexes can thus be understood as an acid-base reaction in the sense of the Lewis definition, in which the ligands (bases) occur as Elektronenpaardonatoren and the central particle (acid) through gaps in its electron configuration as the acceptor.

Complex compounds play an important role in various fields: in technology (for example as a catalyst, ...), in biology ..., in medicine or in analytical chemistry. Compounds with organic ligands are also the subject of organometallic chemistry. Since complexes of transition metals are sometimes very colorful, they are also used as dyes or pigments (Berlin Blue) ...

For a long time, chemists had no idea about the structure of coordinative compounds called "higher order compounds." In addition, many behavioral patterns of complexes with theories of the time could not be explained, such as the stability of cobalt (III) chloride in aqueous solution with the addition of ammonia ... "

As is known, carboxylic acids are only weak acids and are formed on the PTFE during a modification, in particular a radiation-chemical or plasma-chemical modification, in only very low concentrations in the amorphous regions on the PTFE particle surface, wherein the majority of the functional groups are sterically hindered by PTFE chains present ( U. Geissler et al., Angew. Makromol. Chemistry, 256 (1998) 85-88 ). Sterically hindered, ie shielded, inaccessible functional groups then remain ineffective, so that only the low concentration of at most 10 to 15% of the carboxylic acid groups present in contact with a surface for coupling reactions for the production of ionic bonds can be effective.

The inventive solution further coupling groups are provided on the PTFE particle surface in addition to the -COF and / or -COOH groups, the chemical coupling via coordinative bonds and / or ionic bonds between the PTFE particles and the surface more stable and make them more permanent as they are more numerous and more specialized as additional interfaces.

According to the invention, these surfaces according to the invention are prepared with an oil-PTFE lubricant by using modified PTFE particles with -COF and / or -COOH groups and perfluoroalkyl (peroxy) radicals in an oil or an oil mixture with <10% by mass. , preferably <5% by weight and more preferably <2% by weight, based on the amount of PTFE particles in the oil or oil mixture, with organic, olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or or sulfonate and / or sulfate and / or silane compounds are reactive dispersed under mechanical stress and the dispersion is subsequently contacted with the surface.

As modified PTFE particles, it is preferable to use PTFE-particles modified by radiation chemistry or plasma-chemically modified PTFE particles, in particular under the influence of oxygen, by jet chemical or plasma-chemically modified PTFE particles.

As silane compounds advantageously halogen and / or alkoxy-silane compounds are used. As surfaces, metal (oxide) surfaces with the oil-PTFE lubricant dispersion are advantageously used and contacted.

It is of particular importance that the modified PTFE particles in particular perfluoroalkyl (peroxy) radicals have, since these for the radical coupling with the organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulphate and / or silane compounds are required. The degree of coverage of coupling groups coupled to the PTFE surface depends on the concentration of perfluoroalkyl (peroxy) radicals and their accessibility. Due to the mechanical stress and / or increased temperatures during the reactive reaction, the accessibility of the existing organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds significantly improved, so that a higher concentration of coupled coupling groups on the PTFE particle surfaces is realized.

Of particular importance is the mechanical stress in the dispersion of the organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds during the reactive reaction. The organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds tend in part to aggregation with each other, whereby a radical coupling with the PTFE particles difficult or prevented becomes. As a result of the mechanical stress, present and / or formed aggregates of the organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds are largely prevented or broken up with one another that a sufficiently large amount of organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds as reactants for the radical coupling with the PTFE particles available stands. If no further perfluoroalkyl (peroxy) radicals are available on the PTFE, then the uncoupled organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds also via a mostly slower follow-up / further reaction radically coupled with the coupling groups coupled to the PTFE with allyl radicals, so that short graft chains can be formed on coupling groups on the PTFE particle surface.

After the attachment and covalent coupling of the double bond of the organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or Sulfonate and / or sulfate and / or silane compounds as reactants for a perfluoroalkyl (peroxy) radical of the modified PTFE particle, the radical is "transferred" to the coupled molecule analogous to the radical polymerization. This resulting "allyl" radical now shows a significantly lower activity for the subsequent / further reaction and coupling, so that the addition of another double-bond molecule proceeds extremely slowly - especially in the case of the less reactive oil molecule double bonds. Otherwise, there would be an immediate polymerization, which is known from monomers, but not from oleyl compounds.

If the oil or oil mixture used is olefinically unsaturated oils or the oil mixtures contain proportions of olefinically unsaturated oils, the use of a higher amount of organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or or siloxane compounds reaction kinetically more advantageous because some perfluoroalkyl (peroxy) radicals of the PTFE can also react with the olefinically unsaturated double bonds of these oils or oil mixtures, and then no longer for the coupling with the organic olefinically unsaturated phosphite and / or Phosphate and / or sulfonate and / or sulfate and / or siloxane compounds are available. However, even if the oils or oil mixtures used have olefinically unsaturated double bonds, the amount of <10% by mass of organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and or silane compounds, based on the amount of PTFE particles used in the oil or oil mixture, sufficient to realize the couplings according to the invention.

In the event that the oils or oil mixtures used have few or no olefinically unsaturated double bonds, is advantageously also a small amount of the organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds of <5 wt .-%, or even more advantageously of <2 wt .-% based on the amount of PTFE particles in the oil or oil mixture sufficient to effectively with the existing perfluoroalkyl (peroxy) radicals to enter the radical coupling and then with to chemically couple the surface via coordinative bonds and / or ionic bonds, thus enabling a stable permanent bond between the PTFE particles and the surface.

As organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or (halogen and / or alkoxy) silane compounds as coupling groups are advantageously Dioleylhydrogenphosphit, Oleylphosphonsäurediethylester, Allylphosphonsäurediethylester , Oleyl dihydrogen phosphate and / or dioleyl hydrogen phosphate, 2-allylphenyl dihydrogen phosphate and / or bis-2-allylphenylhydrogenphosphate, 2-oleylamidoethanesulfonic acid, 2-acrylamido-2-methylpropanesulfonic acid, oleylsulfate, vinylmethyldichlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, oleylamidopropyltriethoxysilane, allyloxypropyltriethoxysilane. In the case of different surfaces, in particular metal surfaces, the skilled person can determine in a few experiments which of the organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds are suitable for coupling to this surface or is particularly suitable.

The mechanical stress can be advantageously carried out by shearing, which can be realized by stirring, kneading or ultrasound.

As oils or oil mixtures are advantageously mineral oil (s) and / or Polyalphaolefinöl (s) and / or ester oil (s) and / or silicone oil (s), even more advantageously used oils or oil mixtures without olefinically unsaturated double bonds.

The dispersed in an oil or an oil mixture PTFE particles with -COF and / or -COOH groups and optionally still present perfluoroalkyl (peroxy) radicals and the radically coupled coupling groups are then on a surface, advantageously made of metal, plastic, Glass or ceramic, applied by spraying, dipping, knife coating.

The oil-PTFE dispersions according to the invention are prepared by mixing PTFE particles, preferably PTFE (micro) powder particles, which have been modified, in particular by radiation chemistry or plasma-chemical, and thereby form -COF and -COOH groups and perfluoroalkyl groups ( peroxy) radicals, with <5% by weight, based on the amount of PTFE particles in the oil or oil mixture, of organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane Compounds in an oil or oil mixture under mechanical stress, in particular by shearing. The organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds used are preferably EP and / or AW (extreme pressure = AW) additives with olefinically unsaturated double bonds for coupling with the PTFE. The pure substances or else mixtures of organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds in the concentration range according to the invention can be used. The organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds used according to the invention have at least one olefinically unsaturated double bond per molecule for the free-radical coupling reaction with the PTFE before the reactive reaction with the PTFE , Depending on the radical concentration of the PTFE (micro) powder used, one skilled in the art can find out with few attempts which amount and type of organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or or siloxane compounds are optimal for the particular application.

It is also advantageous if the modified PTFE (micro) powder in a liquid containing at least oil or an oil mixture, homogenized and reacted under mechanical stress, advantageously shearing, reactive.

Also advantageous is the addition of PFPE (PFPE ... perfluoropolyether) to the oil-PTFE lubricant in the concentration <25% by weight and preferably <10% by weight, based on the amount of PTFE (micro-) used. Powder in PTFE oil lubricant, after reactive reaction of the PTFE (micro) powder to the coupling groups coupled to the PTFE via radical reactions.

The chemically coupled molecules of the coupling groups on the surface of the PTFE particles are bound via covalent bonds after a radical coupling reaction, whereby the surface of the PTFE (micro) powder particles in addition to the above-described low concentration of accessible, less active -COF and - COOH groups is additionally equipped with further, much more active, in particular metal substrate affinity coupling groups.

The degree of coverage of the surface depends on the concentration of radicals as well as the accessibility to these radicals on PTFE which is preferably modified by irradiation with electron and / or gamma rays, the structure and consequently the accessibility of the olefinically unsaturated molecules enriched on the PTFE particle surface organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds to these radicals, from the temperature and shear conditions, ie from the reaction conditions during the homogenization and reactive reaction in the oil or oil mixture used.

By intensive stirring, for example by means of an UltraTurrax and / or Zahnscheibenrührers an externally homogeneous dispersion is achieved. In this case, the organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds, which are preferably incompatible or incompatible with the oil or oil mixture, accumulate as a pure substance or as a mixture preferably on the Particle surface of the dispersed PTFE (micro) powder on. Kinetically preferred then reacts the olefinically unsaturated double bond of the organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds or mixtures thereof with the perfluoroalkyl (peroxy) radicals on the PTFE - (Micro-) powder particle surface, and there are formed via radical coupling reactions in the temperature range up to 200 ° C and preferably to 150 ° C covalent bonds. The optimum temperature-time regime and the required shear rate for the reactive reaction can be easily determined by the expert by a few experiments.

Advantageously, the dispersion can be treated in addition to stirring by means of ultrasound by the mixture (if possible in the circulation) is passed directly to the ultrasonic probe and is dispersed in the ultrasonic field. A sole ultrasound treatment for producing the oil-PTFE lubricant according to the invention is possible if prior to the ultrasound treatment in an upstream step, a dispersion of the PTFE in an oil or oil mixture together with the organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or sulfate and / or siloxane compounds is produced, whereby a very good uniform distribution of the organic olefinically unsaturated coupling groups on the surface of the PTFE particles is achieved.

The stability of the oil-PTFE lubricant is generated by the electrostatic negative charge of the PTFE particles during the homogenization and reactive conversion / dispersion, which is detectable by Akustophorese. The covalent bonding of the organic olefinically unsaturated coupling groups is realized by the radical reaction. The resulting PTFE particles in the oil / PTFE lubricant which have been specially modified for surface adhesion have a substantially improved (solid) lubricant effect as a result of the additional, coupled, (metal) surface affinity coupling groups. Due to the electrostatic negative charge of the PTFE particles, the PTFE particles repel each other in the oil-PTFE lubricant, resulting in a stable dispersion without PTFE sedimentation. Depending on the PTFE concentration, the size of the PTFE particles and the charge separation quality (depending on the shear during the dispersion), the dispersion can condense downwards by gravity, due to slight movement of this dispersion by pumping, stirring or convection in the system Redispersion of the PTFE in the oil-PTFE lubricant leads.

With further advantage, the oil-PTFE lubricants according to the invention thus produced can also contain further additives, such as, for example, carbon blacks and / or graphite (s) and / or CNT (carbonanotubes) and / or MoS ₂ and / or waxes and / or PFPE (perfluoropolyethers). Oil) and / or foreign polymer components, such as (ultrahigh molecular weight) polyethylene fine powder and / or unmodified and / or preferably radiation-chemically modified perfluoropolymer powder, and / or stabilizers, such as oxidation stabilizer (s), antioxidants / radical scavengers and / or heat stabilizer (s), in proportions up to 5% by mass, which may be added depending on the chemical structure and function before, during and preferably after the reactive conversion / dispersion. The PTFE-foreign solid components remain in the forced-mixed system in the oil-PTFE lubricant and can sediment in sedentary system with a sedimentation, for example, the foreign particle size, the density difference between impurity component (s) and oil medium and the viscosity of the oil-PTFE lubricant is dependent.

Especially in slow-running units, ie in the mixed friction range, the oil-PTFE system according to the invention has an effect Lubricant or as a lubricant additive in oils or fats advantageous. If, in the mixed friction region, the liquid (to) to viscous component (s) of the lubricants (oils, greases or pastes) are displaced from the gap by the pressure of the aggregate components, these tribologically loaded components are more or less in direct contact together. This generates / generates increased friction resulting in (a) frictional energy losses and (b) increased wear. The oil-PTFE lubricants according to the invention now ensure under such conditions, when the oil or oil mixture is pressed / displaced from the gap as a liquid lubricant component that the PTFE is fixed as a solid lubricant component on the (metal) substrate surface in Reibspalt and chemically coupled and so advantageously acts as a solid lubricant on the (metal) substrate surface and reduces both the friction coefficient and the wear.

The chemically coupled coupling groups on the PTFE particle surface are accessible and surface-effective in comparison to the low concentration of less effective -COOH and -COF groups directly on the PTFE particle surface. This enhanced effect of the modified PTFE in the oil-PTFE lubricant according to the invention is illustrated by higher welding forces in the VKA and in the Almen-Wieland test. After electrostatic attraction and attachment to a (metal) surface or to a metal (oxide) surface, with the metal additionally functioning as a ground or counter pole, fixation of the PTFE occurs depending on the group density of the coupled coupling groups on the PTFE Particle surface. As a result, in addition to the electrostatic attraction, these PTFE particles are also fixed on the substrate surface by means of coordinative bonds and / or ionic bonds which, in the mixed friction region, are advantageously used for filming due to the pressing forces. lead to fixed PTFE films on the surface. The coupled, so fixed on the surface PTFE is effective in addition to the solid lubricant effect as a local oil thickener and oil reservoir. In this way, very good run-in and emergency running properties are realized, which are also reflected in the VKA and in the Almen-Wieland test by high welding values.

The stable oil-PTFE lubricants according to the invention can be used completely or proportionally or else as a concentrate for the production of lubricants, in particular for specialty lubricants and / or high-performance lubricants for use in moving parts with tribological requirements. The stable oil-PTFE lubricants according to the invention can be used, for example, in transmissions, in particular control transmissions or transmissions for power transmission, or in bearings, in particular in ball bearings, rolling element bearings, slide bearings, or in piston machines. Advantageously, the stable ÖI PTFE lubricants according to the invention, packaged in high performance lubricants, for the realization of optimal run-in and emergency running properties of Reibkontaktpartnern by the electrostatic interaction, the adhesive interaction and the chemical fixation of the PTFE (micro) powder particles based on the functional Groups and coupled coupling groups are applied to the PTFE. The use of dispersion stabilizers is not necessary, but without effect on the properties or stability of the inventive oil-PTFE lubricants possible.

The homogenization and reactive conversion can be carried out in heatable / temperature-controlled reaction vessels. With regard to the size and type of the reaction vessel, (a) the modified PTFE (micro) powder is introduced for small batches (laboratory batches up to 1 kg of dispersion) and the oil or oil mixture and then the organic olefinically unsaturated phosphite and / or phosphate and / or or sulfonate and / or sulfate and / or siloxane compounds are added with stirring, advantageously heated to the reaction temperature and then dispersed under mechanical stress by stirring the inventive oil PTFE lubricant and reacted reactively, or (b) for larger batches (Small scale> 1 kg of dispersion or in production) submitted the oil or oil mixture and with stirring the modified PTFE (micro) powder and the organic olefinically unsaturated phosphite and / or phosphate and / or sulfonate and / or Sulfur and / or siloxane compounds added as pure substance or mixture and the mixture heated to the reaction temperature t and then under mechanical stress by stirring reactively dispersed the oil-PTFE lubricant according to the invention and reactively reacted.

It is important for the process according to the invention that the homogenization and reactive conversion be carried out under mechanical stress, for example shearing. For this purpose, devices such as toothed disc stirrers and / or UltraTurrax stirrer with circumferential speeds of v _u ~ 15 m / s, preferably v _u ~ 20 m / s, and particularly preferably v _u ~ 23 m / s, can be used.

The use of ultrasound during and / or after the homogenization and reactive conversion / dispersion of the reaction mixture is furthermore advantageous.

For the preparation of the oil-PTFE lubricants according to the invention, modified PTFE (micro) powders of virgin PTFE and / or PTFE Waste and / or PTFE Regenerat- / Recyclat materials are used.

The oil-PTFE lubricants according to the invention are stable and it is also possible to dispense with the use of dispersion auxiliaries or redispersing devices. In lubricants with an additive to the invention produced ÖI PTFE lubricant, the dispersed and surface / surface surface modified modified PTFE (micro) powder particles remain active and actively circulate in a lubricant circulation system, if they are not already fixed on the surface.

The stable oil-PTFE lubricants produced according to the invention are advantageously usable above all as lubricants in slow-running aggregates, that is to say at low sliding speeds in order to avoid stick-slip. Likewise, the stable oil PTFE lubricants produced according to the invention can also be used in fats or for the production of fats.

In the production of ÖI-PTFE lubricants according to the invention, the PTFE agglomerates present in the PTFE (micro) powder must also be broken down by the mechanical stress again to PTFE primary particles and distributed, and it must during the radical reaction a Agglomeration of the PTFE particles are prevented. The mechanical stress, advantageously by shearing, of the PTFE particles simultaneously achieves a permanent charge separation and a negative charge of the PTFE particles, which leads to the formation of the stable oil-PTFE lubricants according to the invention. The stability of the oil-PTFE lubricants in the form of a dispersion in the context of the present invention means that only a compression of the oil-PTFE lubricant without sedimentation of the PTFE occurs within days or months. Furthermore, according to the invention, the addition of dispersion aid (s) and dispersion stabilizer (s) can be partly or even completely omitted. Likewise, a post-treatment of unsaturated oils or oil fractions in the oil-PTFE lubricant by hydrogenation of the olefinic double bonds is possible.

The invention will be explained in more detail below with reference to several exemplary embodiments.

Comparative Example 1a:

Ester oil with 10% by weight of PTFE

In a 250 ml three-necked flask with pure nitrogen gassing / gas supply, an Ultraturrax stirrer and a short reflux condenser with Bunsen valve 135 g TMP (Esteröl: Synative ES TMP 05) and 15 g of PTFE micropowder (Zonyl ^® MP 1100 DuPont, emulsion polymer, irradiated commercially) and stirred for 30 min at 5,000 rev / min under nitrogen purge. The mixture is then heated with stirring to 130 ° C and 4 hours at 130 ° C at 16,000 rev / min intensively stirred. After cooling, a stable TMP-PTFE dispersion is present, which easily condenses on standing and in which no PTFE sediments. In the VKA (four-ball apparatus) test, comparatively pure TMP was tested against the TMP-PTFE dispersion. For the pure TMP, a welding force after ( DIN 51 350 ) of 1.6 kN and wear (after DIN 51 350 ) of 2.61 mm. In contrast, a welding force of 2.8 kN and a wear of 0.62 mm were determined for the TMP-PTFE dispersion. Compared to the TMP-PTFE dispersion (2.8 kN = 100%), the values for the pure TMP for the welding force are approx. 43% lower, while the wear is considerably higher and more than 4 times higher.

Comparative Example 1b:

Ester oil with 10% by weight of PTFE and a phosphate compound without olefinically unsaturated double bond

In a 250 ml three-necked flask with pure nitrogen fumigation / gas supply, an UltraTurrax stirrer and a short reflux condenser with Bunsen valve 135 g of TMP (ester oil: Synative ES TMP 05), 15 g of PTFE micropowder (Zonyl ^® MP 1100) and 1 ml of AP63 (Crafol AP 63, Isotridecyldihydrogenphosphat, without olefinically unsaturated double bond) and 30 min stirred at 5,000 rpm under nitrogen purge. The mixture is then heated with stirring to 130 ° C and 4 hours at 130 ° C at 16,000 rev / min intensively stirred. After cooling, a TMP / AP63 PTFE dispersion is present, which solidifies more strongly on standing and shows a first sedimentation after about 1 week. In the VKA test, the TMP / AP63 PTFE dispersion was comparatively investigated. For the TMP / AP63 PTFE dispersion, a welding force of 2.7 kN and a wear of 0.47 mm were determined. Compared to the TMP-PTFE dispersion (2.8 kN = 100%), the value of the welding force in the TMP / AP63 PTFE dispersion is similar, while the wear is lowered due to the unbound phosphate compound.

Example 1a:

Ester oil with 10% by weight PTFE with a phosphite compound with olefinically unsaturated double bonds

Analogously to comparative example 1b are in a 250 ml three-necked flask with pure nitrogen gassing / gas supply, an Ultraturrax stirrer and a short reflux condenser with Bunsen valve 135 g TMP (Esteröl: Synative ES TMP 05) and 15 g of PTFE micropowder (Zonyl ^® MP 1100), and 1 ml of AP-240L ^(® Duraphos AP-240L, dioleyl hydrogen phosphite) were charged and stirred for 30 minutes under a nitrogen purge with 5000 U / min. The mixture is then heated with stirring to 130 ° C and 4 hours at 130 ° C at 16,000 rev / min intensively stirred. After cooling, a stable TMP-PTFE ^AP-240L dispersion is present, which condenses slightly on standing and in which no PTFE sediments. In the VKA test, the TMP-PTFE dispersion from Comparative ^Example 1a with the prepared TMP-PTFE ^AP-240L dispersion was investigated in a ^comparative manner. For the TMP-PTFE ^AP-240L dispersion, a welding force of 4.5 kN and a wear of 0.65 mm were determined. Compared to the TMP-PTFE dispersion, the welding force increases by 60%, while the wear remains almost constant.

Example 1b:

Ester oil with 10% by weight of PTFE with a phosphate compound with olefinically unsaturated double bonds

Analogously to comparative example 1b are in a 250 ml three-necked flask with pure nitrogen gassing / gas supply, an Ultraturrax stirrer and a short reflux condenser with Bunsen valve 135 g TMP (Esteröl: Synative ES TMP 05) and 15 g of PTFE micropowder (Zonyl ^® MP 1100), and 1 ml of APO-128 (Duraphose APO-128, mixture of oleyl dihydrogen phosphate and Dioleylhydrogenphosphat) presented and stirred for 30 min at 5,000 rev / min under nitrogen purge. The mixture is then heated with stirring to 130 ° C and 4 hours at 130 ° C at 16,000 rev / min intensively stirred. After cooling, a stable TMP-PTFE ^APO-128 dispersion is present, which condenses slightly on standing and in which no PTFE sediments. In the VKA test, the TMP-PTFE dispersion from Comparative Example 1a with the produced TMP-PTFE ^APO-128 dispersion was investigated in a comparative manner. For the TMP-PTFE ^APO-128 dispersion, a welding force of 4.8 kN and a wear of 0.69 mm were determined. Compared to the TMP-PTFE dispersion, the welding force increases by about 70%, while the wear remains almost constant.

Comparative Example 2:

PAO with 10 wt.% PTFE

In a 250 ml three-necked flask with pure nitrogen gassing / gas supply, an Ultraturrax stirrer and a short reflux condenser with Bunsen valve 135 g PAO (oil: PAO ... polyalphaolefin / PAO-6) and 15 g of PTFE micropowder (Zonyl ^® MP 1100 ) and stirred for 30 min at 5,000 U / min under nitrogen purge. The mixture is then heated with stirring to 130 ° C and 4 hours at 130 ° C at 16,000 rev / min intensively stirred. After cooling, a stable PAO-PTFE dispersion is present, which condenses more on standing than in Comparative Example 1, and in which no PTFE sediments.

In the VKA test, the pure PAO was measured in comparison with the PAO-PTFE dispersion. For the pure PAO, a welding force of 1.4 kN and a wear of 3.38 mm were determined. By contrast, a welding force of 2.7 kN and a wear of 0.65 mm were determined for the PAO PTFE dispersion. Compared to the PAO-PTFE dispersion (2.7 kN = 100%), the PAO values for the welding force are about 50% lower, while the wear is much higher and more than 5 times higher.

Example 2:

PAO with 10 wt.% PTFE with a phosphite compound with olefinically unsaturated double bonds

Analogously to Comparative Example 2, 135 g PAO (oil: PAO ... polyalphaolefin / PAO-6) and 15 g PTFE micropowder (Zonyl.) Are mixed in a 250 ml three-necked flask with pure nitrogen gas / gas feed, an UltraTurrax stirrer and a short reflux condenser with Bunsen valve submitted ^® MP 1100), and 1 ml of AP-240L ^(® Duraphos AP-240L, dioleyl hydrogen phosphite) and stirred for 30 minutes under a nitrogen purge with 5000 U / min. The mixture is then heated with stirring to 130 ° C and 4 hours at 130 ° C and an additional hour at 150 ° C at 16,000 rev / min intensively stirred. After cooling, a stable PAO-PTFE ^AP-240L dispersion is present, which compacts on standing analogously to Comparative Example 2, and in which no PTFE sediments. The VKA test comparatively examined the PAO-PTFE dispersion from Comparative ^Example 2 with the PAO-PTFE ^AP-240L dispersion produced. For the PAO-PTFE ^AP-24OL dispersion, a welding force of 3.4 kN and a wear of 0.48 mm were determined. Compared to the PAO PTFE dispersion, the welding force increases by about 25%, while the wear is reduced.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007055927 A1 [0002, 0002]
• DE 102011083076 A1 [0002, 0002]
• DE 10351812 A1 [0003]
• DE 10351813 A1 [0003]
• DE 102004016876 A1 [0003]

Cited non-patent literature

• U. Geissler et al., Angew. Makromol. Chemistry, 256 (1998) 85-88 [0029]
• DIN 51 350 [0063]
• DIN 51 350 [0063]

Claims (12)

 Surfaces with an oil-PTFE lubricant containing PTFE particles via -COF and / or -COOH groups and via radically coupled phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane groups are chemically coupled to the surface via a reactive reaction under mechanical stress via coordinative bonds and / or ionic bonds.  Surfaces according to Claim 1, in which PTFE particles are chemically coupled via phosphite and / or phosphate and / or sulfonate and / or silane groups.  Surfaces according to Claim 1, in which the silane groups present are halogen-silane and / or alkoxy-silane groups chemically coupled with the PTFE particles.  Process for the preparation of surfaces with oil-PTFE lubricant, wherein the modified PTFE particles with -COF and -COOH groups and perfluoroalkyl (peroxy) radicals in an oil or an oil mixture with <10 wt .-%, based dispersed on the amount of PTFE particles in the oil or oil mixture, organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds under mechanical stress and subsequently with the surface to be contacted.  The method of claim 4, wherein the PTFE particles are modified by radiation chemistry or plasma-chemically.  The method of claim 4, wherein the PTFE particles are modified under the influence of oxygen radiation chemistry or plasma-chemically.  Process according to Claim 4, in which the oils or oil mixtures used are mineral oil (s) and / or polyalphaolefin oil (s) and / or ester oil (s) and / or silicone oil (s).  A process as claimed in claim 4, in which oils or oil mixtures having a concentration of olefinically unsaturated double bonds of <5% by weight, preferably oils or oil mixtures without olefinically unsaturated double bonds, are used as oils or oil mixtures.  A process as claimed in claim 4, wherein <5% by weight, advantageously <2% by weight, based on the amount of PTFE particles in the oil or oil mixture, of organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate / or sulfonate and / or sulfate and / or silane compounds are used.  A process as claimed in claim 4, in which the organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds are dioleyl hydrogen phosphite, diethyl oleyl phosphonate, diethyl allyl phosphonate, oleyl dihydrogen phosphate and / or dioleyl hydrogen phosphate , 2-allylphenyl-dihydrogenphosphate and / or bis-2-allylphenylhydrogenphosphat, 2-oleylamido-ethanesulfonic acid, oleylsulfate, vinylmethyldichlorosilane, vinyltrichlorosilane, vinyltriethoxysilane, oleylamidopropyltriethoxysilane, allyloxypropyltriethoxysilane be used.  A method according to claim 4, wherein the mechanical stress is achieved by shearing, for example by stirring, kneading or ultrasound.  A method according to claim 4, wherein in an oil or an oil mixture with <5% by weight, based on the amount of PTFE particles in the oil or oil mixture, of organic olefinically unsaturated phosphite and / or phosphonate and / or phosphate - and / or sulfonate and / or sulfate and / or silane compounds under mechanical stress dispersed modified PTFE particles with -COF and -COOH groups and perfluoroalkyl (peroxy) radicals and coupled via radical reactions organic phosphite and / or phosphonate and / or phosphate and / or sulfonate and / or sulfate and / or silane compounds are applied to a surface of metal, plastic, glass or ceramic by means of spraying, dipping, knife coating.