DE102013216651B4 - CHEMICALLY COUPLED SILICONE-PTFE PRODUCTS AND THEIR PRODUCTION PROCESSES - Google Patents

Abstract

Chemically coupled silicone-PTFE products consisting of silicone, which via a reactive reaction with carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, as functional groups and/or radicals and/or silane and siloxane groups or silane groups and/or olefinic unsaturated compound(s) with at least one olefinically unsaturated double bond of a modified PTFE by substitution and/or addition and/or condensation reactions and/or catalyzed (addition) reactions and/or radical (coupling) reactions before and/or during and /or is chemically coupled via covalent bonds after a crosslinking reaction.

Description

The invention relates to the field of chemistry and relates to chemically coupled silicone-PTFE products, such as can be used, for example, in the field of sealing, wiper or wiper technology with tribological requirements, and a method for their production.

"Silicones (also silicones; singular: the silicone or silicone), chemically more precisely poly(organo)siloxanes, is a designation for a group of synthetic polymers in which silicon atoms are linked via oxygen atoms... Molecular chains and/or networks can occur . The remaining free valence electrons of the silicon are saturated with hydrocarbon residues (usually methyl groups). Silicones therefore belong to the group of organosilicon compounds.

Due to their typical inorganic structure on the one hand and the organic residues on the other hand, silicones occupy an intermediate position between inorganic and organic compounds, in particular between silicates and organic polymers. In a way, they are hybrids and have a unique range of properties that no other plastic can match.

Silicones consist of individual siloxane units. The silicon atoms that do not reach their octet (electron shell) due to the formation of bonds to oxygen are saturated with organic residues.

• [M]=R₃SiO_1/2, [D]=R₂SiO_2/2, [T]=RSiO_3/2 und [Q]=SiO_4/2. Ein aus Q-Einheiten konstituiertes Netzwerk entspräche Quarzglas.

The composition of the siloxane unit is determined by considering the fact that each oxygen atom is a bridge between two silicon atoms: R _n SiO( _4-n ) _/2 (n=O, 1, 2, 3), ie a siloxane unit can have up to four further substituents, depending on the number of valences left free on the oxygen. Thus, siloxane units can be mono-, di-, tri- and tetrafunctional. In symbolic notation, this is represented by the letters M (mono), D (di), T (tri) and Q (quatro):

• [M]=R ₃ SiO _1/2 , [D]=R ₂ SiO _2/2 , [T]=RSiO _3/2 and [Q]=SiO _4/2 . A network composed of Q units would correspond to quartz glass.

• • Lineare Polysiloxane mit der Bauform [MD_nM] bzw. R₃SiO[R₂SiO]_nSiR₃ (Bsp. Poly(dimethylsiloxan))
  
  Poly(dimethylsiloxan)
• • Verzweigte Polysiloxane die als verzweigende Elemente trifunktionelle oder tetrafunktionelle Siloxaneinheiten aufweisen. Bauform [M_nD_mT_n]. Die Verzweigungsstelle(n) ist/sind dabei entweder in eine Kette oder einen Ring eingebaut.
• • Zyklische Polysiloxane sind ringförmig aus difunktionellen Siloxaneinheiten aufgebaut. Bauform [Dn].
• • Vernetzte Polysiloxane in dieser Gruppe sind ketten- oder ringförmige Moleküle mit Hilfe von tri- und tetrafunktionellen Siloxaneinheiten zu planaren oder dreidimensionalen Netzwerken verknüpft. Für den Aufbau hochmolekularer Silikone sind Kettenbildung und Vernetzung die dominierenden Prinzipien.

As with organic polymers, the large number of possible compounds is based on the fact that different siloxane units can be linked to one another in the molecule. Based on the systematics of organic polymers, the following groups can be distinguished:

• • Linear polysiloxanes with the structure [MD _n M] or R ₃ SiO[R ₂ SiO] _n SiR ₃ (e.g. poly(dimethylsiloxane))
  
  poly(dimethylsiloxane)
• • Branched polysiloxanes which have trifunctional or tetrafunctional siloxane units as branching elements. Design [M _n D _m T _n] . The branch point(s) is/are built into either a chain or a ring.
• • Cyclic polysiloxanes are built up in rings from difunctional siloxane units. Design [Dn].
• • Crosslinked polysiloxanes in this group are chain or ring-shaped molecules linked to planar or three-dimensional networks with the help of tri- and tetrafunctional siloxane units. Chain formation and crosslinking are the dominant principles for the construction of high molecular weight silicones.

Silicones can be further classified according to the substituents attached to the silicon.
The siloxane backbone can include various hydrocarbons, silicon functional and organofunctional groups can be present. A subdivision into non-, silicon- or organofunctional is therefore appropriate.” (Wikipedia, keyword silicon).

The various processes for preparing siloxanes are in: Winnacker-Küchler (Eds.: Harnisch, H.; Steiner, R.; Winnacker, K.), Chemical Technology, Organic Technology 11, 4th Edition, Vol. 6, Carl Hanser Verlag, Munich, (1982), pp. 830-834 summarized.

Due to their temperature resistance, silicones also have a prominent position in the field of sealing materials and sealing compounds. The tribological properties of silicone products in dry running are classified as ineffective, i.e. silicone products have a poor property profile with regard to sliding friction and wear. The improvement of the tribological properties with regard to sliding friction and wear in silicone products is necessary and desirable for many applications in order to extend the service life of the systems.

“Silicone rubbers are masses that can be converted into a rubber-elastic state and contain poly(organo)siloxanes that have groups that are accessible for crosslinking reactions. Hydrogen atoms, hydroxy groups and vinyl groups, which are located at the chain ends but can also be incorporated into the chain, are predominantly suitable as such. Silicone rubbers contain reinforcing substances and fillers, the type and amount of which have a significant impact on the mechanical and chemical behavior of the silicone elastomers created by crosslinking. Silicone rubbers can be colored with suitable pigments.

Depending on the necessary crosslinking temperature, a distinction is made between cold (RTV) and hot crosslinking (HTV) silicone rubbers (RTV = room temperature crosslinking, HTV = high temperature crosslinking). HTV silicone rubbers are plastically deformable materials. They very often contain organic peroxides for crosslinking. The elastomers produced from this by crosslinking at high temperature are heat-resistant products that are elastic between -40 and 250 °C and are used e.g. B. be used as high-quality sealing, damping, electrical insulation components, cable sheathing and the like ... Another cross-linking mechanism consists in a mostly catalyzed by noble metal compounds addition of Si-H groups to silicon-bonded vinyl groups, both in the polymer chains or on their end are installed. The liquid rubber technology based on this (LSR = Liquid Silicone Rubber) has been established since 1980. The silicone rubber components, which, in contrast to the HTV rubbers described above, have a lower viscosity and are therefore pumpable, are dosed with suitable mixing and dosing machines, mixed and usually processed in injection molding machines. This technology allows high cycle rates due to the short crosslinking time of the rubbers... With the RTV silicone rubbers, a distinction can be made between one- and two-component systems. The first group (RTV-1) crosslinks at room temperature under the influence of atmospheric moisture, the crosslinking taking place by condensation of SiOH groups with the formation of Si-O bonds. The SiOH groups are formed by hydrolysis of SiX groups of an intermediate species formed from a polymer with terminal OH groups and a so-called crosslinker R-SiX3 (X=-O-CO-CH3, -NHR). In the case of two-component rubbers (RTV-2), e.g. B. Mixtures of silicic acid esters (e.g. ethyl silicate) and organotin compounds are used, the crosslinking reaction being the formation of a Si-O-Si bridge from Si-OR and Si-OH by elimination of alcohol... Silicone elastomers are widely used found use in construction as a sealant to fill joints... but they are also used there to make molding and potting compounds and as coatings for fabrics.” (Wikipedia, keywords silicone rubber and silicone elastomers)

In silicone compounds such as silicone rubber and silicone elastomers, the use of PTFE as a solid lubricant has so far only been known as a physical mixture. The mixing of solid lubricants such as PTFE into the liquid starting materials leads to inhomogeneous products that are difficult to reproduce due to sedimentation. In the crosslinked/cured solid product, the interaction of the PTFE with the silicone matrix material is too low in physical mixtures to be effective as a solid lubricant. Only embedded, the PTFE is quickly worn out under tribological, i.e. sliding friction stress and becomes ineffective after being transported away from the friction gap. This is the cause of the poor friction and wear properties, since in a physical mixture there is little or no interaction between the silicone solid and the anti-adhesive PTFE. This explains the lower wear resistance of physically mixed products. Only through further wear do PTFE particles come to the surface and can then become effective. Due to the low interactions described, these PTFE particles are then also quickly rubbed out and transported away, which causes and explains this low wear resistance.

It is also known that PTFE can be degraded by radiation modification to form micropowders containing persistent perfluoroalkyl (peroxy) radicals capable of reacting/free-radically coupling with olefinically unsaturated compounds such as monomers, macromers, oligomers and polymers, and functional groups such as Carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups capable of known reactions in polymer-analogous reactions such as substitution reactions and/or addition reactions. PTFE micropowders can also be produced by special, direct polymerization, such as Zonyl MP™ 1600 (DuPont) or TF 9207 (3M/Dyneon), or by thermomechanical degradation, such as TF 9205 (3M/Dyneon). However, such micropowder products have only very low concentrations of functional groups and/or radicals or, like the TF 9205, no functional groups and/or radicals. It is therefore advantageous to use radiation-chemical modification to generate a concentration of functional groups and/or radicals that is effective with regard to the later modification, based on known knowledge. The conditions for radiation chemical modification of PTFE are State of the art, and the person skilled in the art can estimate in a few experiments which concentrations of functional groups and/or radicals are necessary or optimal for the subsequent modification reactions. The coupling and compatibilization of PTFE with monomeric and/or oligomeric and/or polymeric hydrocarbon compounds has been adequately described ( DE 103 51 814 A1 ; DE 103 51 813 A1 ; DE 103 51 812 A1 ).

According to Baradie, B. et al: Can. J. of Chem. 83, 2005 pp. 553-558, a crosslinked fluorosilicone polymer is known which is synthesized by grafting isocyanate-modified PDMS with a hydroxyl-functionalized fluoropolymer.

Next is from the US 2003/0008935 A1 a fluororesin crosslinked by ionizing radiation, which has been grafted with an organic compound such as vinylsiloxane under ionizing radiation.

A disadvantage of the solutions from the prior art is that silicone and specifically silicone elastomers have inadequate properties with regard to friction and wear for tribological applications.

The object of the present invention consists in specifying chemically coupled silicone-PTFE products with improved properties with regard to friction and wear for tribological applications, as well as a simple and inexpensive method for their production.

The object is solved by the invention specified in the claims. Advantageous configurations are the subject matter of the dependent claims.

The inventive chemically coupled silicone-PTFE products consist of silicone, which via a reactive reaction with carbonyl fluoride and / or carboxylic acid and / or perfluoroalkylene groups as functional groups and / or radicals and / or silane and siloxane groups or silane groups and / or olefinically unsaturated compound(s) with at least one olefinically unsaturated double bond of a modified PTFE by substitution and/or addition and/or condensation reactions and/or catalyzed (addition) reactions and/or radical (coupling) reactions and/or is chemically coupled via covalent bonds during and/or after a crosslinking reaction.

Advantageously, PTFE is via the reactive conversion of carbonyl fluoride and / or carboxylic acid and / or perfluoroalkylene groups as functional groups and / or radicals of the PTFE with the silicone via covalent bonds during substitution and / or addition and / or radical ( Coupling) reactions have arisen, coupled.

Furthermore, advantageously, PTFE is coupled via the reactive conversion of silane groups of the PTFE with the silicone via covalent bonds that have arisen during condensation reactions.

Likewise advantageously, PTFE is coupled via the reactive reaction of silane groups of the PTFE with the silicone via covalent bonds that have arisen during catalyzed reactions.

And also advantageously, PTFE is coupled via the reactive reaction of olefinically unsaturated groups of and/or on the PTFE with the silicone via covalent bonds that have arisen during radical reactions.

It is also advantageous if PTFE is coupled via the reactive reaction of olefinically unsaturated groups of the PTFE with the silicone via covalent bonds that have arisen during catalyzed reactions.

It is also advantageous if silicone rubbers and/or silicone elastomers and/or mixtures of these or one another are present as the silicone.

It is also advantageous if radiation-chemically and/or plasma-chemically modified PTFE is present.

It is also advantageous if the silicone is chemically coupled to modified PTFE by condensation reactions and/or catalyzed reactions and/or radical reactions after the reactive conversion/crosslinking reaction via covalent bonds.

And it is also advantageous if, after the reactive reaction, the silicone with modified PTFE is formed by a platinum-catalyzed reaction of Si-H groups with olefinically unsaturated groups to form covalent Si-C bonds or by a condensation reaction of the Si-OR and/or or Si-O-COR groups to form covalent Si-O-Si bonds or by a radiation-chemically and/or peroxide-initiated radical reaction of the methyl groups on the silicone/silane and/or the olefinically unsaturated double bonds to form covalent C-C bonds on the PTFE and /or silicone is chemically coupled.

It is also advantageous if the crosslinking reactions of the silicone are a catalyzed reaction with tetraalkyl orthosilicate and/or a radical reaction with one or more peroxides and/or by means of high-energy rays.

In the method according to the invention for the production of chemically coupled silicone-PTFE products
- Radiation chemically modified PTFE powder with carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups and/or with persistent perfluoroalkyl (peroxy) radicals
and or
- With at least one silane and at least one siloxane or with at least one silane
and/or with at least one low-molecular compound which has no double bond and at least two identical or different functional groups,
and/or with at least one monomer which has a double bond and at least one further double bond and/or functional group,
and/or with at least one oligomer which has at least one double bond or functional group and at least one further double bond and/or functional group,
and/or with at least one polymer which has at least one double bond or functional group and at least one further double bond and/or functional group,
chemically modified PTFE powder
homogeneously dispersed in silicone/(poly)(organo)siloxane or silicone mixtures and subsequently crosslinked, with the silane and siloxane groups or silane groups formed on the modified PTFE powder particles before and/or during the homogenization and/or before and/or during the crosslinking and/or carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups as functional groups and/or groups with at least one olefinically unsaturated double bond with the silicone or the silicone mixtures by a reactive reaction via substitution and/or addition and/or condensation reactions and / or catalyzed reactions and / or radical reactions are coupled chemically via covalent bonds.

Advantageously, the PTFE powder with at least one low molecular weight compound which has at least two identical and / or different carbonyl fluoride and / or carboxylic acid and / or perfluoroalkylene groups as functional groups and no olefinically unsaturated double bond before the coupling to the PTFE, and / or with at least one monomer having a double bond and at least one other double bond and/or functional group, and/or oligomer having at least one double bond or functional group and at least one other olefinically unsaturated double bond and/or one other functional group, and/or Polymer having at least one double bond or functional group and at least one other olefinically unsaturated double bond and/or one other functional group, and/or modified with at least one silane and siloxane or silane prior to homogenization and/or crosslinking. Likewise advantageously, silicone starting materials for silicone synthesis and/or silicones and/or silicone mixtures with or without additives and/or fillers and/or reinforcing materials are used as dispersants.

Furthermore, advantageously, the homogenization is carried out by means of a mixer, kneader, extruder, stirrer or ultrasound.

And also advantageously silicone rubbers or mixtures thereof or mixtures with silicone elastomers are used as silicone or silicone mixtures.

It is also advantageous if PTFE micropowders are used.

It is also advantageous if the silicone or silicone mixtures are crosslinked by a catalyzed reaction of Si-H groups with olefinically unsaturated groups of poly(organo)siloxanes and/or on PTFE and/or on, with low molecular weight compounds and/or monomers and/or oligomers and/or polymers modified PTFE and/or a catalyzed reaction with tetraalkyl orthosilicate and/or a radical reaction with one or more peroxides and/or high-energy rays.

According to the invention, the chemically coupled silicone-PTFE product according to the invention, which has been produced according to the invention, is used as a material for seals in sealing technology or in scraper or wiper technology with tribological requirements.

For the first time, the silicone-PTFE products according to the invention have improved properties with regard to friction and wear for tribological applications.

This is achieved by, according to the invention, realizing a chemical coupling via covalent bonds between the PTFE and the silicone during the manufacture of the products.

According to the state of the art when mixing in PTFE micropowders as physical cal mixture in solid silicone products, such as silicone rubber, silicone elastomers, silicone resins and fluorosilicones, in which the PTFE particles are only embedded in the silicone matrix, the PTFE is quickly rubbed out under tribological, ie sliding friction stresses, transported away from the friction gap and thus ineffective.
According to the invention, this is changed in that chemical compatibilization is achieved via covalent bonds as a coupling of the PTFE solid lubricant particles with the silicone solid matrix.
This so-called chemical compatibilization and the associated fixation of the PTFE particles on and in the silicone solid matrix by means of covalent bonds prevents the PTFE particles from being rubbed out, or at least makes it significantly more difficult, so that the PTFE in the tribological system/friction gap remains effective for longer. As a result, improved sliding friction properties of the silicone-PTFE products according to the invention and, above all, higher wear resistance of these products are achieved.

For this purpose, PTFE powders are modified with monomers and/or oligomers and/or polymers (consisting of silane and/or siloxane and/or hydrocarbon compounds) such that silane and siloxane groups or silane groups and/or carbonyl fluoride suitable for coupling - and/or carboxylic acid and/or perfluoroalkylene groups as functional groups and/or olefinically unsaturated groups with at least one olefinically unsaturated double bond are formed on the PTFE particle surfaces. These groups and/or the at least one olefinically unsaturated double bond then react in known reactions with groups of the silicone or the silicone mixture via condensation reactions and/or catalyzed coupling and/or crosslinking reactions and/or radical coupling and/or crosslinking reactions before and/or during a crosslinking reaction to form covalent bonds.

After the PTFE powder has been modified, it is homogeneously incorporated into silicone or silicone mixtures. Crosslinking then takes place using known methods.

During the homogenization and/or during the crosslinking, the chemical coupling of the silane and siloxane groups or silane groups and/or carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups as functional groups and/or olefinically unsaturated groups with at least one olefinically unsaturated double bond takes place on the PTFE powder particles with the silicone or the silicone mixtures via condensation reactions and/or catalyzed reactions and/or radical reactions via covalent bonds known to those skilled in the art.

According to the invention, chemically coupled silicone rubber-PTFE or silicone elastomer-PTFE products are advantageously produced via covalent bonds, which through the homogeneous distribution and direct binding of the PTFE to and in the silicone rubber and after crosslinking/vulcanization in the silicone elastomer (network) have improved properties for tribological have applications.

According to the invention, chemically modified PTFE micropowders are used with groups chemically coupled via covalent bonds, which react with them before and/or during the crosslinking reaction of silicone rubbers to form silicone elastomers, and the PTFE particles are thus coupled directly into the network via covalent bonds after crosslinking and are homogeneous are distributed in it.

• - Silane und/oder Siloxane mit kondensationsfähigen Gruppen über Kondensationsreaktionen,
• - Silane und/oder Siloxane mit Methylgruppen über radikalische Kopplungs- und/oder Vernetzungsreaktionen mittels Peroxid und/oder energiereicher Strahlung (Elektronen-, Gamma- und/oder Röntgenstrahlung),
• - olefinisch ungesättigte Gruppen über radikalische Kopplungs-/Vernetzungsreaktionen mittels Peroxid und/oder energiereicher Strahlung (Elektronen-, Gamma- und/oder Röntgenstrahlung),
• - olefinisch ungesättigte Gruppen über die durch Edelmetallverbindungen katalysierte Kopplung/Addition von Si-H-Gruppen an Silanen und/oder Siloxanen,
• - Silane und/oder Siloxane mit Si-H über die durch Edelmetallverbindungen katalysierte Kopplung/Addition an Doppelbindungen.

The reactive conversion/chemical coupling reaction, which takes place with the formation of covalent bonds, takes place according to known reaction mechanisms in silicone chemistry via those coupled to the PTFE

• - silanes and/or siloxanes with condensable groups via condensation reactions,
• - Silanes and/or siloxanes with methyl groups via radical coupling and/or crosslinking reactions using peroxide and/or high-energy radiation (electron, gamma and/or X-ray radiation),
• - olefinically unsaturated groups via radical coupling/crosslinking reactions using peroxide and/or high-energy radiation (electron, gamma and/or X-ray radiation),
• - olefinically unsaturated groups via the coupling/addition of Si-H groups to silanes and/or siloxanes catalyzed by noble metal compounds,
• - Silanes and/or siloxanes with Si-H via coupling/addition to double bonds catalyzed by noble metal compounds.

It is possible for the person skilled in the art to state without further ado, or even with a few attempts, which PTFE modifications and/or reaction mechanisms can be combined and which cannot be combined.

• (1) Bei den RTV-Silikonkautschuken der Gruppe RTV-1, die bei Raumtemperatur unter dem Einfluss von Luftfeuchtigkeit durch Kondensation von Si-OH-Gruppen unter Bildung von Si-O-Bindungen vernetzen, werden silan- und siloxan- oder silanmodifizierte PTFE-Mikropulver mit hydrolysierbaren Vernetzergruppen [als -R-SiX₃ und/oder -R-SiR*X₂ und/oder -R-SiR*R**X (beispielsweise mit X = -O-CO-CH₃, -NHR*** und R = Alkylen und/oder Phenylen und/oder Arylen und/oder -Siloxan- und R*, R** = Alkyl und vorzugsweise Methyl und/oder Phenyl und/oder Aryl und/oder Vinyl und/oder Allyl und/oder Siloxan-Rest und R*** = H und/oder Alkyl und vorzugsweise Methyl und/oder Phenyl und/oder Aryl)], wobei als Vernetzergruppe -R-SiX₃ bevorzugt und üblicherweise auch im Silikonkautschuk-Produkt vorhanden ist oder verwendet wird, homogen in die Masse eingemischt. Die Verbindungen mit den Silan- und/oder Siloxan-Gruppen zur Kopplung am PTFE über kovalente Bindungen werden durch die dem Fachmann bekannten Reaktionen mit den funktionellen Gruppen, wie Carbonylfluorid- und/oder Carbonsäure- und/oder Perfluoralkylen-Gruppen, am PTFE über polymeranaloge Umsetzungen durch Substitutions- und/oder Additionsreaktionen und/oder über radikalische Kopplung über die Perfluoralkyl-(peroxy-)radikale gekoppelt. Als bevorzugte Silan- und/oder Siloxan-Verbindungen mit hydrolysierbaren Vernetzergruppen -R-SiX₃ werden Aminoalkylsilane und/oder Aminoalkylsiloxane direkt zur PTFE-Modifizierung eingesetzt. Weiterhin bevorzugt können mit Aminogruppen modifizierte PTFE-Mikropulver auch mit Epoxy- und/oder Glycidoxyalkylsilan und/oder Epoxy- und/oder Glycidoxyalkylsiloxan reaktiv unter kovalenter Bindung umgesetzt werden. Für die Silan- und/oder Siloxanmodifizierung von PTFE mit hydrolysierbaren Vernetzergruppen -R-SiX₃ über die radikalische Kopplung mit Perfluoralkyl-(peroxy)radikalen am PTFE werden bevorzugt Silane und/oder Siloxane mit Vinyl- und/oder Allyl- und/oder (Meth-)Acryl- und/oder Oleyl-Gruppen eingesetzt. Die Modifizierungsreaktionen werden nach bekannten Verfahren zur PTFE-Modifizierung durchgeführt, wobei der Fachmann die entsprechenden Silane und/oder Siloxane so auswählt, dass unerwünschte Nebenreaktionen vermieden werden. Als bevorzugte silan- und/oder siloxanmodifizierte PTFE-Mikropulver in RTV-1-Silikonkautschuken werden die unter Essigsäureabspaltung vernetzenden Systeme für tribologische Anwendungen eingesetzt.
• (2) Bei den Zweikomponentenkautschuken (RTV-2), in die als Vernetzer z. B. Gemische aus Kieselsäureestern (z.B. Ethylsilicat) und zinnorganische Verbindungen (wie z.B. Dibutylzinndilaurat) als Vulkanisationsbeschleuniger eingesetzt werden, werden silan- und siloxan- oder silan-modifizierte PTFE-Mikropulver mit Vernetzergruppen der Form -R-SiY₃ und/oder -R-SiR*Y₂ und/oder -R-SiR*R**Y (beispielsweise mit Y = -O-Alkyl und vorzugsweise -OCH₃ und/oder -O-C₂H₅ und R = Alkylen und/oder Phenylen und/oder Arylen und/oder -Siloxan- und R*, R** = Alkyl und vorzugsweise Methyl und/oder Phenyl und/oder Aryl und/oder Vinyl und/oder Allyl und/oder Siloxan-Rest), wobei -R-SiY₃ als Vernetzergruppe bevorzugt und üblicherweise auch im Silikonkautschuk-Produkt vorhanden ist oder verwendet wird, homogen in die Masse eingemischt. Die Verbindungen mit den Silan- und/oder Siloxan-Gruppen werden über kovalente Bindungen durch die dem Fachmann bekannten Reaktionen mit den funktionellen Gruppen, wie Carbonylfluorid- und/oder Carbonsäure- und/oder Perfluoralkylen-Gruppen, am PTFE über polymeranaloge Umsetzungen durch Substitutions- und/oder Additionsreaktionen und/oder über radikalische Kopplung über die Perfluoralkyl-(peroxy-)radikale am PTFE gekoppelt. Als bevorzugte Silan- und/oder Siloxan-Verbindungen mit hydrolysierbaren Vernetzergruppen -R-SiX₃ werden Aminoalkyltrialkoxysilane und/oder Aminoalkyltrialkoxysiloxane direkt zur PTFE-Modifizierung eingesetzt. Weiterhin bevorzugt können mit Aminogruppen-modifizierte PTFE-Mikropulver auch mit Epoxy- und/oder Glycidoxyalkyltrialkoxysilan und/oder Epoxy- und/oder Glycidoxyalkyltrialkoxysiloxan reaktiv unter kovalenter Bindung umgesetzt werden. Für die Silan- und/oder Siloxanmodifizierung von PTFE mit hydrolysierbaren Vernetzergruppen -R-SiX₃ über die radikalische Kopplung mit den Perfluoralkyl-(peroxy-)radikalen am PTFE werden bevorzugt Silane und/oder Siloxane mit Vinyl- und/oder Allyl- und/oder (Meth-)Acryl- und/oder Oleyl-Gruppen eingesetzt. Die Modifizierungsreaktionen werden nach bekannten Verfahren zur PTFE-Modifizierung durchgeführt, wobei der Fachmann die entsprechenden Silane und/oder Siloxane so auswählt, dass unerwünschte Nebenreaktionen vermieden werden. Als bevorzugte silanmodifizierte PTFE-Mikropulver in RTV-2-Silikonkautschuken werden die unter Alkoholabspaltung vernetzenden, am PTFE gekoppelten Aminopropyltrialkoxysilane und/oder Vinyltrialkoxysilane für tribologische Anwendungen eingesetzt.
• (3) Bei den HTV-Silikonkautschuken als noch plastisch verformbare Materialien werden zur Herstellung oder vor der Vernetzung oder Vulkanisation modifizierte PTFE-Mikropulver homogen eingemischt, die kovalent gekoppelte Verbindungen mit olefinisch ungesättigten Doppelbindungen auf der PTFE-Partikeloberfläche besitzen. Wichtig ist eine effektive Zer- und Verteilung der PTFE-Produkte/Agglomerate, um eine homogene Mischung vor der Vulkanisation zu erhalten. Durch die Vulkanisation/Hochtemperaturvernetzung, vorzugsweise unter Einsatz von Vulkanisationshilfsmitteln, wie organische Peroxide und/oder auch durch energiereiche Strahlung, wie Elektronen-, Gamma- und/oder Röntgenstrahlung, werden die mit olefinisch ungesättigten Doppelbindungen modifizierten PTFE-Mikropulver an und in das Silikonnetzwerk kovalent gebunden, wodurch wärmebeständige, tribologisch ausgerüstete elastische Silikon-PTFE-Produkte erhalten werden. Diese Silikonkautschuk-PTFE-Mischungen können auch bei niedrigen Temperaturen durch energiereiche Strahlung, wie Elektronen-, Gamma- und/oder Röntgenstrahlung, vernetzt werden. Als modifizierte PTFE-Mikropulver, die mit Verbindungen mit olefinisch ungesättigten Doppelbindungen modifiziert sind, können für diese Silikonkautschuk-PTFE-Produkte PTFE-Mikropulver eingesetzt werden, die an der PTFE-Partikeloberfläche über kovalente Bindungen gekoppelte Verbindungen beispielsweise mit den Vinylsilan- und/oder Vinylsiloxan- und/oder Allylsilan- und/oder Allylsiloxan-Gruppen und/oder olefinisch ungesättigte Monomere und/oder Oligomere und/oder Polymere mit mindestens noch einer olefinisch ungesättigten Doppelbindung im Molekül nach der Kopplung mit dem PTFE besitzen. Diese Verbindungen werden durch die Reaktion mit den funktionellen Gruppen, wie die Carbonylfluorid- und/oder Carbonsäure- und/oder Perfluoralkylen-Gruppen, am PTFE über polymeranaloge Umsetzungen durch Substitutions- und/oder Additionsreaktionen und/oder durch die Radikalkopplungsreaktion mit den Perfluoralkyl-(peroxy-)radikalen am PTFE gekoppelt, wobei im gekoppelten Molekül noch mindestens eine olefinisch ungesättigte Doppelbindung vorhanden ist. Als bevorzugte Verbindungen werden Aminoverbindungen mit mindestens einer olefinisch ungesättigten Doppelbindung, wie beispielsweise Allylamin und/oder Aminopropyldimethylvinylsilan und/oder Aminopropylmethyldivinylsilan und/oder Aminopropyltrivinylsilan, direkt zur PTFE-Modifizierung eingesetzt. Weiterhin bevorzugt können beispielsweise mit Aminogruppen modifizierte PTFE-Mikropulver auch mit Epoxy- und/oder Glycidoxyalkyltrivinylsilan und/oder Epoxy- und/oder Glycidoxyalkyltrivinylsiloxan reaktiv unter kovalenter Bindung umgesetzt werden. Für die Silan- und/oder Siloxanmodifizierung von PTFE mit olefinisch ungesättigten Doppelbindungen über die radikalische Kopplung mit den Perfluoralkyl-(peroxy)radikalen am PTFE werden bevorzugt Silane und/oder Siloxane mit mindesten zwei gleichen oder unterschiedlichen, olefinisch ungesättigten Doppelbindungen im Molekül in Form von Vinyl- und/oder Allyl- und/oder Crotonyl- und/oder (Meth-)Acryl- und/oder Oleyl-Gruppen eingesetzt. Als modifiziertes PTFE-Mikropulver mit olefinisch ungesättigten Doppelbindungen können auch mit olefinisch ungesättigten Ölen, wie beispielsweise mit Trimethylolpropantrioleat und/oder Dioleylhydrogenphosphit und/oder Di- und/oder Trioleylphosphat, gekoppelte PTFE-Mikropulver und/oder oligomere und/oder polymere/makromolekulare Homopolymere und/oder Copolymere und/oder Terpolymere mit Butadien- und/oder Isopren- und/oder Norbornen-Einheiten in der Kette, wie beispielsweise Oligomere und/oder Polymere von NBR (Nitrilkautschuk/Nitrile Butadiene Rubber) und/oder XNBR (carboxylgruppenhaltiger Nitrilkautschuk) und/oder SBR (Styrol-Butadien-Kautschuk) und/oder SBS (Styrol-Butadien-Styrol-Blockcopolymer) und/oder NR (Naturkautschuk/Natural Rubber) gekoppelte PTFE-Mikropulver, eingesetzt werden.

(4a) Bei Einsatz des Zweikomponentenvemetzungssystems, in dem eine durch Edelmetallverbindungen, meist Pt-/Platin-katalysierte Addition von Si-H-Gruppen an siliciumgebundene olefinisch ungesättigte Doppelbindungen/Gruppen, vorzugsweise Vinylgruppen, abläuft, und das vor der Vernetzung als getrennte Komponenten A (üblicherweise mit Katalysator) und B (üblicherweise mit Verzweiger/Vernetzer) hergestellt und gelagert werden, wird das mit olefinisch ungesättigten Doppelbindungen ausgerüstete PTFE-Mikropulver in nur eine Komponente oder vorzugsweise entsprechend der Zusammensetzung/Bestandteile in beide Komponenten vor dem Mischen und Vernetzen homogen so eingemischt, dass keine ungewünschten Reaktionen in einer der Komponenten stattfinden. Da es sich um flüssige bis pastöse (Ausgangs-)Komponenten, beispielsweise getrennt nach A-Komponente (mit Katalysator) und B-Komponente (mit Verzweiger/Vernetzer) meist gleicher Konsistenz handelt, ist es vorteilhaft, in beiden Komponenten zur Einstellung vergleichbarer Viskositätsverhältnisse das modifizierte PTFE-Mikropulver unter der vorgenannten Randbedingung homogen einzumischen. Wichtig ist eine effektive Zer- und Verteilung des modifizierten PTFE-Mikropulvers und vor allem von PTFE-Mikropulveraggregaten/-agglomeraten. In flüssigen Komponenten kann die Zer- und Verteilung mittels Zahnscheibenrührer (Dispermat) erfolgen, wobei durch die Scherung/innere Reibung eine Ladungstrennung im System eine elektrostatische/negative Aufladung der PTFE-Mikropulver-Partikel erfolgt, wodurch eine stabile Dispersion der PTFE-Komponente erreicht wird, was vorteilhaft für die (Weiter-)Verarbeitung ist. In pastösen Systemen können entsprechend der Konsistenz Mischaggregate wie z.B. Mischer und/oder Kneter und/oder Zweischneckenextruder und/oder Planetwalzenextruder eingesetzt werden. Dabei ist dem Fachmann hinreichend bekannt, dass auf die getrennte Handhabung und Verarbeitung der jeweiligen Komponenten A und B zu achten ist und welche modifizierten PTFE-Mikropulver-Partikel in welche oder beide Komponenten wie eingemischt werden müssen.The selection of the particular modified PTFE micropowder by the person skilled in the art takes place in accordance with the envisaged crosslinking reaction, with known crosslinking reactions customary in practice being used. Such known methods using the invention Starting materials for the production of the silicone-PTFE products according to the invention are as follows:

• (1) In the case of the RTV silicone rubbers of the RTV-1 group, which crosslink at room temperature under the influence of atmospheric humidity through the condensation of Si-OH groups to form Si-O bonds, silane and siloxane or silane-modified PTFE Micropowder with hydrolyzable crosslinking groups [as -R-SiX ₃ and/or -R-SiR*X ₂ and/or -R-SiR*R**X (for example with X=-O-CO-CH ₃ , -NHR** * and R = alkylene and/or phenylene and/or arylene and/or -siloxane- and R*, R** = alkyl and preferably methyl and/or phenyl and/or aryl and/or vinyl and/or allyl and/or Siloxane residue and R*** = H and/or alkyl and preferably methyl and/or phenyl and/or aryl)], where -R-SiX ₃ is preferred as the crosslinking group and is usually also present or used in the silicone rubber product, homogeneously mixed into the mass. The compounds with the silane and/or siloxane groups for coupling to the PTFE via covalent bonds are formed by the reactions known to those skilled in the art with the functional groups, such as carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, on the PTFE via polymer analogs Reactions coupled by substitution and/or addition reactions and/or by free radical coupling via the perfluoroalkyl (peroxy) radicals. Aminoalkylsilanes and/or aminoalkylsiloxanes are used directly as preferred silane and/or siloxane compounds with hydrolyzable crosslinking groups —R—SiX ₃ for PTFE modification. Furthermore, preferably, PTFE micropowders modified with amino groups can also be reactively reacted with epoxy- and/or glycidoxyalkylsilane and/or epoxy- and/or glycidoxyalkylsiloxane with covalent bonding. Silanes and/or _siloxanes with vinyl and/or allyl and/or ( Meth)acrylic and/or oleyl groups are used. The modification reactions are carried out according to known methods for PTFE modification, with the person skilled in the art selecting the appropriate silanes and/or siloxanes in such a way that undesired side reactions are avoided. The preferred silane- and/or siloxane-modified PTFE micropowders in RTV-1 silicone rubbers are the systems that crosslink with elimination of acetic acid for tribological applications.
• (2) In the two-component rubbers (RTV-2), in which z. B. Mixtures of silicic acid esters (e.g. ethyl silicate) and organotin compounds (e.g. dibutyltin _dilaurate ) are used as vulcanization accelerators. SiR*Y ₂ and/or -R-SiR*R**Y (for example with Y = -O-alkyl and preferably -OCH ₃ and/or -OC ₂ H ₅ and R = alkylene and/or phenylene and/or arylene and/or -siloxane and R*, R** = alkyl and preferably methyl and/or phenyl and/or aryl and/or vinyl and/or allyl and/or siloxane residue), where -R-SiY ₃ as crosslinking group is preferably and usually also present or used in the silicone rubber product, homogeneously mixed into the mass. The compounds with the silane and/or siloxane groups are formed via covalent bonds by the reactions known to those skilled in the art with the functional groups, such as carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, on the PTFE via polymer-analogous reactions by substitution and/or addition reactions and/or via free radical coupling via the perfluoroalkyl (peroxy) radicals on the PTFE. Aminoalkyltrialkoxysilanes and/or aminoalkyltrialkoxysiloxanes are used directly as preferred silane and/or siloxane compounds with hydrolyzable crosslinking groups —R—SiX ₃ for PTFE modification. With further preference, PTFE micropowders modified with amino groups can also be reactively reacted with epoxy- and/or glycidoxyalkyltrialkoxysilane and/or epoxy- and/or glycidoxyalkyltrialkoxysiloxane with covalent bonding. Silanes and/or _siloxanes with vinyl and/or allyl and/or or (meth)acrylic and/or oleyl groups are used. The modification reactions are carried out according to known methods for PTFE modification, with the person skilled in the art selecting the appropriate silanes and/or siloxanes in such a way that undesired side reactions are avoided. The preferred silane-modified PTFE micropowders in RTV-2 silicone rubbers used for tribological applications are the aminopropyltrialkoxysilanes and/or vinyltrialkoxysilanes which crosslink with elimination of alcohol and are coupled to the PTFE.
• (3) In the case of the HTV silicone rubbers, which are still plastically deformable materials, for the production or before the crosslinking or Vul kanization-modified PTFE micropowders are mixed in homogeneously, which have covalently coupled compounds with olefinically unsaturated double bonds on the PTFE particle surface. Effective fragmentation and distribution of the PTFE products/agglomerates is important in order to obtain a homogeneous mixture before vulcanization. As a result of vulcanization/high-temperature crosslinking, preferably using vulcanization auxiliaries such as organic peroxides and/or high-energy radiation such as electron, gamma and/or X-ray radiation, the PTFE micropowders modified with olefinically unsaturated double bonds become covalent on and in the silicone network bound, whereby heat-resistant, tribologically equipped elastic silicone-PTFE products are obtained. These silicone rubber-PTFE mixtures can also be crosslinked at low temperatures using high-energy radiation such as electron, gamma and/or X-ray radiation. As modified PTFE micropowders, which are modified with compounds with olefinically unsaturated double bonds, PTFE micropowders can be used for these silicone rubber PTFE products, the compounds coupled to the PTFE particle surface via covalent bonds, for example with the vinylsilane and/or vinylsiloxane - and/or allylsilane and/or allylsiloxane groups and/or olefinically unsaturated monomers and/or oligomers and/or polymers with at least one olefinically unsaturated double bond in the molecule after coupling with the PTFE. These compounds are formed through the reaction with the functional groups, such as the carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, on the PTFE via polymer-analogous reactions through substitution and/or addition reactions and/or through the radical coupling reaction with the perfluoroalkyl-( peroxy) radicals coupled to the PTFE, with at least one olefinically unsaturated double bond still being present in the coupled molecule. Preferred compounds used directly for modifying PTFE are amino compounds having at least one olefinically unsaturated double bond, such as, for example, allylamine and/or aminopropyldimethylvinylsilane and/or aminopropylmethyldivinylsilane and/or aminopropyltrivinylsilane. With further preference, for example, PTFE micropowders modified with amino groups can also be reactively reacted with epoxy- and/or glycidoxyalkyltrivinylsilane and/or epoxy- and/or glycidoxyalkyltrivinylsiloxane with covalent bonding. Silanes and/or siloxanes with at least two identical or different olefinically unsaturated double bonds in the molecule in the form of Vinyl and/or allyl and/or crotonyl and/or (meth)acrylic and/or oleyl groups are used. As a modified PTFE micropowder with olefinically unsaturated double bonds, PTFE micropowders coupled with olefinically unsaturated oils, such as trimethylolpropane trioleate and/or dioleyl hydrogen phosphite and/or di- and/or trioleyl phosphate, and/or oligomers and/or polymers/macromolecular homopolymers and /or copolymers and/or terpolymers with butadiene and/or isoprene and/or norbornene units in the chain, such as oligomers and/or polymers of NBR (nitrile rubber/Nitrile Butadiene Rubber) and/or XNBR (carboxyl-containing nitrile rubber) and /or SBR (styrene butadiene rubber) and/or SBS (styrene butadiene styrene block copolymer) and/or NR (natural rubber) coupled PTFE micropowders.

(4a) When using the two-component crosslinking system, in which an addition of Si-H groups to silicon-bonded olefinically unsaturated double bonds/groups, preferably vinyl groups, catalyzed by noble metal compounds, usually Pt/platinum, takes place, and that before crosslinking as separate components A (usually with a catalyst) and B (usually with a branching agent/crosslinking agent) are produced and stored, the PTFE micropowder equipped with olefinically unsaturated double bonds is divided into only one component or, preferably, according to the composition/ingredients, into both components prior to mixing and crosslinking so homogeneously mixed in that no undesirable reactions take place in one of the components. Since the (starting) components are liquid to pasty, for example separated into A component (with catalyst) and B component (with branching agent/crosslinking agent), it is usually of the same consistency, so it is advantageous to set comparable viscosity ratios in both components mix in modified PTFE micropowder homogeneously under the aforementioned boundary condition. Effective comminution and distribution of the modified PTFE micropowder and, above all, PTFE micropowder aggregates/agglomerates is important. In liquid components, the disintegration and distribution can take place using a toothed disc stirrer (Dispermat), whereby the shearing/internal friction causes a charge separation in the system and an electrostatic/negative charging of the PTFE micropowder particles, resulting in a sta Bile dispersion of the PTFE component is achieved, which is advantageous for (further) processing. In pasty systems, mixing units such as mixers and/or kneaders and/or twin-screw extruders and/or planetary roller extruders can be used depending on the consistency. The person skilled in the art is sufficiently aware that care must be taken to ensure separate handling and processing of the respective components A and B and which modified PTFE micropowder particles must be mixed into which or both components and how.

The silicone rubber components A and B homogenized in this way with modified PTFE micropowder must be thoroughly homogenized according to their consistency using mixing and dosing machines and/or mixing units in order to achieve an effective vulcanization/crosslinking reaction. Processing on injection molding machines is possible using appropriate mixing units due to the short crosslinking time of the rubber, as is used in the LSR process, for example.

As modified PTFE micropowders for the catalyzed Si-H addition to olefinically unsaturated double bonds, PTFE micropowders can be used for these silicone rubber-PTFE products analogously to process variant (3), the compounds with vinylsilane coupled via covalent bonds to the PTFE particle surface - and/or vinylsiloxane and/or allylsilane and/or allylsiloxane groups and/or olefinically unsaturated monomers and/or oligomers and/or polymers with at least one olefinically unsaturated double bond after the coupling with the PTFE. These compounds are formed by the reaction with the functional groups, such as carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, on the PTFE via polymer-analogous reactions by substitution and/or addition reactions and/or by a radical coupling reaction with the perfluoroalkyl-(peroxy -)radicals coupled to the PTFE. Preferred compounds used directly for modifying PTFE are amino compounds having at least one olefinically unsaturated double bond, such as, for example, allylamine and/or aminopropyldimethylvinylsilane and/or aminopropylmethyldivinylsilane and/or aminopropyltrivinylsilane. Furthermore, preferably, PTFE micropowders modified with amino groups, for example, can also be reactively reacted with epoxy- and/or glycidoxyalkyltrivinylsilane and/or epoxy- and/or glycidoxyalkyltrivinylsiloxane with covalent bonding. Silanes and/or siloxanes with at least two identical or different olefinically unsaturated double bonds in the molecule in the form of Vinyl and/or allyl and/or crotonyl and/or (meth)acrylic and/or oleyl groups are used. As a modified PTFE micropowder with olefinically unsaturated double bonds, PTFE micropowders coupled with olefinically unsaturated oils, such as trimethylolpropane trioleate and/or dioleyl hydrogen phosphite and/or di- and/or trioleyl phosphate, and/or oligomers and/or polymers/macromolecular homopolymers and /or copolymers and/or terpolymers with butadiene and/or isoprene and/or norbornene units in the chain, such as oligomers and/or polymers of NBR and/or XNBR and/or SBR and/or SBS and/or NR coupled PTFE micropowders can be used.

It is important that when the individual components A and B of the two-component crosslinking system are produced separately, it is important to ensure that components A and B are prepared separately and mixed with the individual substances in such a way that no undesirable reaction can take place in one of these components, which Expert can also realize without problems with knowledge of the individual ingredients in components A and B in the production. Suitable fillers and/or reinforcing materials can also be used to adapt/equalize the viscosity ratios of components A and B.(4b) When using the two-component crosslinking system, in which an addition of Si-H groups to silicon-bonded silicon-bonded Si-H groups catalyzed by noble metal compounds, usually Pt olefinically unsaturated double bonds/groups, preferably vinyl groups, the silane- and/or siloxane-modified PTFE micropowder containing Si-H bonds is homogeneously mixed into the component with Si-H bonds.

If the silane- and/or siloxane-modified PTFE micro-powder containing Si-H bonds is to be homogeneously mixed into both components, care must be taken when preparing the individual components A and B of the two-component crosslinking system with regard to the composition of the components that no unwanted reactions occur planned elastomer production/vulcanization/crosslinking take place, i.e. that the component with the Pt catalyst does not contain any olefinically unsaturated double bonds/groups, since otherwise the silane- and/or siloxane-modified PTFE micropowder containing Si-H bonds in this mixture already has a Coupling and possibly crosslinking reaction would take place.

Since the (starting) components are liquid to pasty, for example separated into A component (usually with a catalyst) and B component (usually with a branching agent/crosslinking agent), it is usually of the same consistency Mix in the modified PTFE micropowder in equal parts in accordance with the viscosity ratios, taking into account the boundary conditions mentioned above, or also use suitable fillers and/or reinforcing materials. Effective comminution and distribution of the modified PTFE micropowder and, above all, PTFE micropowder aggregates/agglomerates is important. In liquid components, the disintegration and distribution can take place using a toothed disc stirrer (Dispermat), whereby the shearing/internal friction in the system causes the PTFE micropowder particles to be electrostatically/negatively charged, thereby achieving a stable dispersion of the PTFE component, which advantageous for (further) processing. Depending on the consistency, mixers and/or kneaders and/or twin-screw extruders and/or planetary roller extruders can be used in pasty systems. The person skilled in the art is sufficiently aware that care must be taken to ensure that components A and B are handled and processed separately.

The silicone rubber components A and B homogenized in this way with modified PTFE micropowder must be homogenized well according to the consistency using mixing and dosing machines and/or mixing units in order to achieve an effective vulcanization/crosslinking reaction. Processing on injection molding machines is possible using appropriate mixing units due to the short crosslinking time of the rubber, as is used in the LSR process, for example.

PTFE micropowders which have silane and/or siloxane compounds with SiH bonds coupled via covalent bonds to the PTFE particle surface can be used as modified PTFE micropowders with SiH bonds for these silicone rubber PTFE products . These silane and/or siloxane compounds are formed by reaction with the functional groups, such as carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, on the PTFE via polymer-analogous reactions through substitution and/or addition reactions and/or through a radical coupling reaction coupled with the perfluoroalkyl (peroxy) radicals on the PTFE. Preferred silane and/or siloxane compounds with Si-H bonds for PTFE micropowder modification are compounds which are covalently bonded to the PTFE particle surface via amide groups and/or which have olefinically unsaturated double bonds and free radicals in a graft reaction couple with the perfluoroalkyl (peroxy) radicals. Silanes and/or siloxanes with Si-H bonds and at least one olefinically unsaturated double bond in the molecule are preferred for the silane and/or siloxane modification of PTFE micropowder via free-radical coupling with the perfluoroalkyl (peroxy) radicals on the PTFE of vinyl and/or allyl and/or crotonyl and/or (meth)acrylic and/or oleyl groups. With further preference, for example, PTFE micropowders modified with amino groups can also be reactively reacted with epoxy- and/or glycidoxyalkylsilane and/or epoxy- and/or glycidoxyalkylsiloxane with Si-H bonds with covalent bonding.

Continuing with (4a) and (4b), the PTFE micropowders modified/equipped with olefinically unsaturated double bonds and the silane- and siloxane- or silane-modified PTFE micropowders containing Si-H bonds can also be mixed together, optionally also with other Pt -Catalyst-free component(s) are homogenized, which are then crosslinked by addition and homogenization with a catalyst component (preferably a Pt catalyst component).
Furthermore, the PTFE micropowders equipped with olefinically unsaturated double bonds and the silane- and/or siloxane-modified PTFE micropowders containing Si-H bonds can be mixed in separately according to the ingredients/composition of the respective A and B components, so that there is no unwanted/premature reaction/crosslinking/vulcanization.

The enumeration of the silane and/or siloxane substances and the other reagents for PTFE modification is not complete. However, the general methods and substances and reagents for this are known from the prior art, so that the person skilled in the art can select from the known knowledge which compounds he uses for which PTFE modifications, with a substance also being used for reactions on different functional groups and/or or radicals and/or thermally activatable groups can be used. Based on this knowledge, the person skilled in the art can plan the process and, with just a few experiments, clarify which modification is optimal for the production of the PTFE modifications according to the invention that he desires as precursors for the production of the chemically coupled silicone-PTFE products. He can also use the modified PTFE compounds as a pure substance or as a mixture, and the person skilled in the art can use his knowledge to select the composition of the mixture components accordingly, since he knows which compounds can be used together and which ones are not, and how he can clean the modified PTFE powder before use if necessary.

In the chemically coupled/compatibilized silicone-PTFE products according to the invention, the PTFE is stably integrated into the material after vulcanization/crosslinking. As a result of the pretreatment/modification and, advantageously, the electrostatic/negative charging of the PTFE micropowder, the mixture is sufficiently compatible and processing-stable before vulcanization/crosslinking and cannot demix or phase separate. After vulcanization/crosslinking, the coupled PTFE cannot “simply” be rubbed out of the silicone-PTFE products under sliding friction conditions due to the covalent bond with the matrix material. A further advantage is that the synthesis and modification reactions can be carried out according to customary/known procedures, which means that rapid implementation in practice is possible. It should only be ensured that a sufficiently homogeneous dispersion of the PTFE is achieved/realized before and/or during the reaction of the modified PTFE micropowder.

• - dass in den silan- und/oder siloxan-modifizierten PTFE-Mikropulvern (als Vorprodukte/Ausgangsstoffe) die Silan- und/oder Siloxan-Verbindungen an der PTFE-Partikeloberfläche fixiert sind, d.h. mit dem PTFE über kovalente Bindungen chemisch gekoppelt sind und so kompatibilisiert mit dem Silikon-(Reaktions-)System vorliegen,
• - dass die (strahlen- und/oder plasma- und/oder silan- und/oder siloxanmodifizierten PTFE-Mikropulver im Silikon-(Reaktions-)System durch die reaktive Umsetzung in der Vernetzungsreaktion/Vulkanisation entweder in einer direkten Reaktion der funktionellen Gruppen und/oder Radikale am PTFE und/oder über die Reaktion der am PTFE gekoppelten Silan- und/oder Siloxan-Verbindungen und/oder der gekoppelten niedermolekularen (ohne olefinisch ungesättigte Doppelbindung, aber mit funktionellen Gruppen) und/oder der monomeren (mit olefinisch ungesättigte Doppelbindung(en) und gegebenenfalls mit funktionellen Gruppen) und/oder der oligomeren und/oder der polymeren/makromolekularen Verbindungen mit funktionellen Gruppen und/oder der olefinisch ungesättigten Doppelbindungen, mit der Silikon-Matrix kovalente Bindungen eingehen und so chemisch gekoppelt vorliegen,
• - dass die PTFE-Partikel mit der Silikon-Matrix nach der Vernetzung/Vulkanisation mindestens teilweise über kovalente Bindungen chemisch gekoppelt vorliegen,

In the context of this invention, chemically “coupled/compatibilized” and compatible should be understood to mean

• - That in the silane and/or siloxane-modified PTFE micropowders (as precursors/starting materials), the silane and/or siloxane compounds are fixed to the PTFE particle surface, ie are chemically coupled to the PTFE via covalent bonds and such are compatible with the silicone (reaction) system,
• - That the (radiation and/or plasma and/or silane and/or siloxane-modified PTFE micropowders in the silicone (reaction) system result from the reactive conversion in the crosslinking reaction/vulcanization either in a direct reaction of the functional groups and/or or radicals on the PTFE and/or via the reaction of the silane and/or siloxane compounds coupled to the PTFE and/or the coupled low molecular weight (without olefinically unsaturated double bond, but with functional groups) and/or the monomeric (with olefinically unsaturated double bond( en) and optionally with functional groups) and/or the oligomeric and/or the polymeric/macromolecular compounds with functional groups and/or the olefinically unsaturated double bonds, enter into covalent bonds with the silicone matrix and are thus chemically coupled,
• - that the PTFE particles are at least partially chemically coupled with the silicone matrix after crosslinking/vulcanization via covalent bonds,

• - dass durch chemische Reaktionen in Form von Additions- und/oder Substitutions- und/oder Radikalreaktionen unter Ausbildung von kovalenten Bindungen über Verzweigungen ein Elastomer-/Polymernetzwerk entsteht und so ein vernetztes Material entsteht, das thermoplastisch nicht mehr verarbeitbar ist und in Lösemitteln höchstens quellbar, aber nicht mehr löslich ist,
• - dass durch Vulkanisation ein Kautschuk zu einem Elastomer vernetzt wird, d.h. die plastischen Eigenschaften des Kautschuks/Stoffsystems gehen verloren, und „der Stoff wird mittels des Verfahrens der Vulkanisation vom plastischen in einen elastischen Zustand überführt“ (Wikipedia, Stichwort Vulkanisation).

Within the scope of this invention, vulcanization/curing/crosslinking is to be understood as

• - That an elastomer/polymer network is created by chemical reactions in the form of addition and/or substitution and/or free radical reactions with the formation of covalent bonds via branches and a crosslinked material is thus created that can no longer be processed thermoplastically and at most swells in solvents , but is no longer soluble,
• - that a rubber is crosslinked to an elastomer by vulcanization, ie the plastic properties of the rubber/material system are lost, and "the material is converted from a plastic to an elastic state by means of the vulcanization process" (Wikipedia, keyword vulcanization).

• - unter Kautschuk: das unvernetzte oder teilvernetzte, noch thermoplastisch vearbeitbare Produkt, und
• - unter Elastomer und Gummi: das vernetzte, thermoplastisch nicht mehr verarbeitbare Produkt

verstanden werden. Da die Vernetzungsdichte in Elastomeren sehr weitmaschig ist und so auch die Verarbeitbarkeit weite Bereiche, d.h. keine klaren Grenzen umfasst, wird allgemein der Übergang vom Kautschuk zum Elastomer oft fließend verwendet. „Rubber“ aus dem englischsprachigen Raum wird z.B. überlappend mit Kautschuk und Gummi übersetzt und in technischen Bereichen verwendet, wie z.B. NR „Natural Rubber“ und „Naturkautschuk“, was die Problematik der klaren Definition/Begriffstrennung unterstreicht.In the prior art, the terms caoutchouc, gum, elastomer and rubber are often used very broadly and not clearly delimited/defined. Within the scope of this invention:

• - under rubber: the non-crosslinked or partially crosslinked product that can still be processed as a thermoplastic, and
• - under elastomer and rubber: the cross-linked product that can no longer be processed as a thermoplastic

be understood. Since the crosslinking density in elastomers is very wide-meshed and the processability also covers a wide range, ie no clear limits, the transition from rubber to elastomer is often used in a fluent manner. "Rubber" from the English-speaking world, for example, is translated overlapping with caoutchouc and rubber and used in technical areas, such as NR "Natural Rubber" and "Natural Rubber", which underlines the problem of the clear definition/separation of terms.

Within the scope of this invention, reactive conversion is to be understood as meaning chemical coupling, modification and/or crosslinking reactions in which the reaction partners react with one another, forming covalent bonds, and are chemically coupled and/or crosslinked.

Advantageously, the radiation-modified PTFE has carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups and/or persistent perfluoroalkyl (peroxy) radicals that are bonded directly to the PTFE/via covalent bonds ver are anchored, which result in a modification reaction with the above-mentioned, corresponding starting materials, functionally modified PTFE micropowders, which then after dispersion in the poly(organo)siloxanes (silicone rubber and/or silicone elastomer precursors) and after the reactive reaction with coupling and covalent bonding, it being possible for the functionally modified PTFE micropowder to be dispersed before and/or during the reactive reaction, as long as the mass is still plastically workable.

One reason is that the chemically covalent coupling of the PTFE, for example in a silicone rubber, silicone elastomer, silicone resin and fluorosilicone material or component, makes it much more difficult or in many cases no longer possible to rub the PTFE out and transport it away from the friction gap for the poorer properties with regard to friction and wear, namely little or no interaction between the silicone matrix material and the PTFE described in the prior art as anti-adhesive in a physical mixture. The chemically covalent coupling of the PTFE via the silane- and/or siloxane-modified PTFE materials makes it more difficult or, depending on the degree of coupling with the silicone matrix material, prevents the PTFE from being rubbed out and transported away from the friction gap, which significantly improves the lubricating properties.

Another problem with elastomers - and not only with silicone elastomers - in sealing systems under tribological application conditions is the (stable) transfer of PTFE to the counter body in order to obtain a tribologically optimal sliding friction system. If the PTFE is not equipped with additional special coupling groups for the corresponding substrate and is only transferred to the counter-body by adsorption, it is quickly removed from the tribological system by the "erasing" effect of the (silicone) elastomer matrix component (e.g. in sealing systems) and is therefore ineffective, what results in increased wear. This is significantly improved precisely according to the invention. In addition, however, it is also advantageous that, in addition to the coupling and integration of the solid lubricant PTFE into the silicone matrix of silicone rubber, silicone elastomer, silicone resin and fluorosilicone parts/components, the PTFE also has adhesive groups with a preferred affinity for another material, i.e. with Adhesion groups is modified / equipped. Advantageously, the PTFE particles can also be equipped with other functions directly on the PTFE or coupled via spacer groups, for example with coupling groups with a special affinity for the respective material surfaces in the lubricated system, which also has an advantageous effect on the tribological properties with regard to friction and wear in the (Tribo) system affects.

It is therefore advantageous that, in addition to the coupling and integration of the solid lubricant PTFE in the silicone matrix of silicone rubber, silicone elastomer, silicone resin and fluorosilicone parts/components, the PTFE also has coupling/adhesion groups with an increased affinity for the counter body used, i.e. with Coupling/adhesion groups are modified/equipped so that a more stable transfer to the counter-body occurs through covalent and/or ionic bonding/fixing of the PTFE on the counter-body surface.

Within the scope of this invention, coupling groups with a special affinity for (metal) material surfaces are to be understood as chemically coupled via covalent bonds (organo)phosphorus and/or (organo)sulfur compounds, for example in the form of chemically modified phosphoric acid and /or phosphate and/or thiophosphate and/or dithiophosphate and/or phosphonic acid and/or phosphonate and/or phosphinic acid and/or phosphinate compounds present as (partially) esterified and/or salts, and /or chemically coupled sulfur compounds in the form of sulphide and/or sulphate and/or sulphonate and/or sulphonic acid esters which, under tribological conditions, bring about improved interaction and coupling of the PTFE component with (metal) material surfaces.

Radiation-chemically modified and/or chemically modified PTFE micropowders are used as PTFE. Radiation-chemically modified PTFE micropowders were produced by electron and/or gamma radiation modification and have carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups and/or persistent perfluoroalkyl (peroxy) radicals, and can optionally also be thermally and/or or modified chemically via known reactions such as substitution and/or addition and/or free radical reactions. Chemically modified PTFE micropowders were chemically modified using known reactions such as substitution and/or addition and/or free-radical reactions from micropowders that were produced thermomechanically or by a special polymerization and, if necessary, additionally modified by radiation chemistry.

For example, Zonyl™ MP1100 and/or Zonyl™ MP1200 from DuPont can be used as PTFE micropowder. Also, PTFE micropowders that were produced in a special PTFE polymerization process, such as DuPont's Zonyl™ MP1600 and/or the TF 9207 from 3M/Dyneon, which has advantageously been subsequently modified with at least 50 kGy of electron and/or gamma radiation and/or has been produced by thermomechanical degradation, such as the TF 9205 from 3M/Dyneon, which has advantageously been subsequently modified with at least 50 kGy electron and/or gamma radiation can be used.

The micropowders can be used in pure form or as a mixture. It is advantageous to use radiation-modified PTFE micropowder made from PTFE emulsion polymer and/or PTFE suspension polymer from PTFE primary material/virginal PTFE and/or PTFE recyclate/regenerate/secondary material, for example from the machining of PTFE semi-finished products or mixtures thereof. For example, before use, the micropowders are modified by radiation chemistry and optionally also chemically by means of substitution and/or addition and/or free-radical reactions according to known methods and thus have functional groups and/or olefinically unsaturated double bonds, depending on the modification. Appropriately modified micropowders made from PTFE suspension polymers are particularly preferred as primary and/or secondary goods.

It is advantageous to use PTFE as a primary PTFE product, such as TF 1750 (3M/Dyneon) irradiated with 500 kGy gamma rays and/or recycled PTFE/regenerate from the machining of semi-finished products irradiated with 700 kGy gamma rays, with the PTFE recyclate / regenerate is ground before and preferably after the radiation modification to micropowder.

Unirradiated PTFE with no or too low a concentration of functional groups and/or radicals is advantageously modified by electron or gamma ray modification in the presence of (atmospheric) oxygen with at least 50 kGy by known methods, otherwise the advantageous effect of chemical coupling and compatibility is too low or non-existent. Although the density of the functional groups on carbonyl fluoride and/or carboxylic acid and of the radicals after irradiation with 50 kGy is low, it is in many cases sufficient for chemical coupling and compatibilization. It is also well known to those skilled in the art that the concentration of functional groups and radicals is highly dependent on the type of irradiation, i.e. the irradiation conditions, which is state of the art of PTFE irradiation modification. When using radiation-modified and/or radiation-modified and chemically-modified PTFE micropowder, liquid poly(organo)siloxane components are used to produce silicone rubber and/or silicone elastomers with the input of energy, for example due to shearing (internal friction) due to charge separation and negative charging of the PTFE Particle (processing) stable dispersions with no tendency to sedimentation. However, depending on the PTFE micropowder properties, the PTFE concentration and the viscosity in the (silicone) (reaction) system without agitation, in these dispersions, a slow densification of the dispersion without sedimentation by gravity is generally observed, i.e. the chemically coupled/compatibilized Although poly(organo)siloxane-PTFE dispersion can condense towards the bottom, and two phases/layers are formed without sedimentation/depositing of PTFE micropowder solids at the bottom, these can, however, be quickly homogenized again by stirring. The formation and densification of the poly(organo)siloxane PTFE dispersion is determined by the PTFE micropowder properties, specifically the breakdown of the PTFE, the particle size and particle size distribution (depending on the type and the radiochemical and/or chemical modification of the PTFE micropowder used). and the type and concentration of modification sites on the PTFE and/or by PTFE micropowder properties that may have been changed directly by chemical modification via polymer-analogous reactions and by the parameters in the process control for the production of the poly(organo)siloxane PTFE dispersion, i.e. it is influenced dependent on a number of complex interrelated factors. Charge separation during dispersion with the input of shearing energy, such as shearing using an Ultra-Turrax and/or toothed disc stirrer and/or internal shearing of the system using ultrasound, results in the electrostatic/negative charging of the PTFE particles, which causes the PTFE particles to repel each other in the Dispersion and stable dispersion of the PTFE in the reaction system. The electrostatic/negative charging of the PTFE particles is primarily the driving force behind preventing PTFE sedimentation. Even with dilution, no sedimentation is observed, only a concentration-related lower dispersion layer thickness in the reaction system without stirring or active dispersion, i.e. at rest. Due to an electrostatic/negative charging of the PTFE particles in liquid starting materials and, if necessary, a chemical coupling with at least one of the silicone starting components on the PTFE particle surface via covalent bonds, there is sufficient time before and/or during vulcanization/curing/crosslinking, i.e. for processing and manufacture of homogeneous, crosslinked silicone rubber-PTFE and crosslinked silicone elastomer-PTFE products.

The inventive chemically coupled silicone-PTFE products based on Sili Konkautschuk and/or silicone elastomer are used in the field of sealing, wiper and wiper technology with tribological requirements. These modified silicone PTFE products are made by reactive reaction via product synthesis and/or product modification prior to and/or during the molding of commercial materials. Chemically coupled/compatibilized silicone PTFE products for seal, wiper and wiper technology can be used, for example, as a molded material, sealant or (silicone rubber and/or silicone elastomer) sealing material with applications in mechanical engineering, automotive engineering, aerospace . Compared to the pure silicone product without a PTFE modification or with PTFE powder that is physically mixed in, the silicone-PTFE products bonded with the PTFE micropowder modified according to the invention lead to improved tribological properties when used in moving parts with tribological requirements, even at higher temperatures sliding friction and wear.

The advantage of the solution according to the invention is that after vulcanization/crosslinking the modified PTFE micropowder is chemically coupled and fixed in the silicone-PTFE products according to the invention via covalent bonds and thus has improved tribological properties with regard to sliding friction and wear. Sealing, wiper and wiper materials made entirely or partially from the materials according to the invention therefore have a higher functional reliability and service life. This provides the person skilled in the art with a tool for producing chemically coupled and compatibilized silicone-PTFE products and a method for reactive conversion with chemical coupling and compatibilization of the PTFE with the matrix materials for the various fields of application with tribological requirements.

The invention is explained in more detail below using several exemplary embodiments.

Example 1: Production of the modified PTFE-MP-1

50 g PTFE micropowder TF 9205 (3M/Dyneon, irradiated with 500 kGy gamma radiation) in 250 ml dried NMP (1-methyl -2-pyrrolidone) with 10 g of 3-aminopropyldivinylmethoxysilane for 10 min at room temperature while gassing with ultra-pure nitrogen at 5,000 rpm. The reaction mixture is then heated to 190° C. and stirred at 10,000 rpm for 2 hours. After cooling, the PTFE is separated and extracted 5 times with methanol, washed and dried.

The silane-modified PTFE micro powder (PTFE-MP-1) can be used for the production of silicone PTFE products by cold and hot vulcanization.

Example 2: Production of the modified PTFE-MP-2

50 g of PTFE micropowder Zonyl™ MP 1200 (DuPont) in 250 ml of dried NMP (1-methyl-2-pyrrolidone) are placed in a 500 ml three-necked flask with ultra-pure nitrogen gassing/gas supply, an Ultra-Turrax stirrer and a short reflux condenser 10 g of hexamethylenediamine were stirred for 10 min at room temperature while gassing with ultra-pure nitrogen at 5,000 rpm. The reaction mixture is then heated to 190° C. and stirred at 10,000 rpm for 2 hours. After cooling, the PTFE is separated and washed several times with methanol and thus freed from unbound hexamethylenediamine. This cleaned PTFE product is dispersed together with 5 g (3-glycidoxypropyl)vinyldimethoxysilane in methanol using an Ultra-Turrax at 10,000 rpm for 1 hour, filtered off, extracted 5 times with methanol, washed and dried.
The silane-modified PTFE micro powder (PTFE-MP-2) can be used for the production of silicone PTFE products by cold and hot vulcanization.

Example 3: Production of the modified PTFE-MP-3

50 g PTFE micropowder TF 1750 (3M/Dyneon, irradiated with 1,000 kGy electron beam) in 250 ml dried NMP (1-methyl -2-pyrrolidone) with 10 g of divinyl-1,3-dimethyl-1,3-dimethoxydisiloxane for 10 min at room temperature with ultra-pure nitrogen gassing at 5,000 rpm. The reaction mixture is then heated to 130° C. and stirred at 10,000 rpm for 4 hours. After cooling, the PTFE is separated and extracted 5 times with methanol, washed and dried.
The silane-modified PTFE micro powder (PTFE-MP-3) can be used for the production of silicone PTFE products by cold and hot vulcanization.

Example 4: Production of the modified PTFE-MP-4

50 g PTFE micropowder TF 1750 (3M/Dyneon, irradiated with 1,000 kGy electron beam) in 250 ml of dried NMP (1-methyl-2-pyrrolidone) with 10 g of dioleyl hydrogen phosphite (Duraphos AP 240L) for 10 min at room temperature with ultra-pure nitrogen gassing at 5,000 rpm. The reaction mixture is then heated to 130° C. and stirred at 10,000 rpm for 4 hours. After cooling, the PTFE is separated and extracted 5 times with petroleum ether, washed and dried.
The modified PTFE micropowder (PTFE-MP-4) can be used (a) for the production of silicone PTFE products by cold vulcanization based on the Pt-catalyzed Si-H addition crosslinking, (b) for the production of silicone PTFE -products by cold vulcanization based on tetraethyl silicate/dibutyltin dilaurate and (c) for the manufacture of peroxide crosslinked silicone PTFE products by hot vulcanization.

Example 5: Production of the modified PTFE-MP-5

50 g PTFE micropowder TF 1750 (3M/Dyneon, irradiated with 1,000 kGy electron beam) in 250 ml dried NMP (1-methyl -2-pyrrolidone) with 10 g of ester oil TMP 05 (trimethylolpropane trioleate) for 10 min at room temperature while gassing with ultra-pure nitrogen at 5,000 rpm. The reaction mixture is then heated to 130° C. and stirred at 10,000 rpm for 4 hours. After cooling, the PTFE is separated and extracted 5 times with petroleum ether, washed and dried.
The oil-modified PTFE micropowder (PTFE-MP-5) can be used (a) for the production of silicone PTFE products by cold vulcanization based on the Pt-catalyzed Si-H addition crosslinking and (b) for the production of, with peroxide cross-linked silicone-PTFE products by hot vulcanization.

Example 6: Production of the modified PTFE-MP-6

50 g PTFE powder recyclate 07 (PTFE suspension polymer recyclate from machining of semi-finished products, unmixed, crushed, with 700 kGy gamma -irradiated and ground to micropowder) in 250 ml dried NMP (1-methyl-2-pyrrolidone) with 15 g polybutadiene (Aldrich, Mn =1530 -2070 (VPO)) for 10 min at room temperature with ultra-pure nitrogen gassing at 5,000 rpm touched. The reaction mixture is then heated to 130° C. and stirred at 10,000 rpm for 4 hours. After cooling, the PTFE is separated and extracted 5 times with petroleum ether, washed and dried.
The polybutadiene-modified PTFE micropowder (PTFE-MP-6) thus produced can be used (a) for the production of silicone PTFE products by cold vulcanization based on Pt-catalyzed Si-H addition crosslinking and (b) for the production of silicone-PTFE products crosslinked with peroxide by hot vulcanization.

Example 7: Production of the modified PTFE-MP-7

50 g PTFE micropowder TF 1750 (3M/Dyneon, irradiated with 1,000 kGy electron beam) in 250 ml dried NMP (1-methyl -2-pyrrolidone) with 5 g APO-128 (mixture of oleyl dihydrogen phosphate and dioleyl hydrogen phosphate, ^Duraphos® APO-128) and 5 ml aminopropyltriethoxysilane for 10 min at room temperature with ultra-pure nitrogen gassing at 5,000 rpm. The reaction mixture is then heated to 130° C. and stirred at 10,000 rpm for 4 hours. The reaction mixture is then heated to 190° C. and dispersed at 10,000 rpm for a further 2 hours. After cooling, the PTFE is separated and extracted 5 times with petroleum ether and 5 times with ethanol, washed and dried.
The modified PTFE micro powder (PTFE-MP-7) can be used for the production of silicone PTFE products by cold vulcanization based on tetraethyl silicate/dibutyltin dilaurate.

Example 8: Preparation of Oligosiloxane OS-1

100 g of octamethylcyclotetrasiloxane are mixed with 50 g of KOH powder in a 250 ml 2-necked flask with paddle stirrer and heated to 140° C. in an oil bath. With stirring, an oligosiloxane with increasing viscosity is formed. After 15 minutes, the reaction is interrupted by cooling. The low-viscosity oligosiloxane intermediate OS-1 is used for further coupling reactions.

Example 9: Preparation of Oligosiloxane OS-2

100 g of octamethylcyclotetrasiloxane are mixed with 50 g of KOH powder in a 250 ml 2-necked flask with paddle stirrer and heated to 140° C. in an oil bath. With stirring, an oligosiloxane with increasing viscosity is formed. After about 30 minutes, the stirrer is removed and the product is post-condensed/tempered at 140° C. for about 2 hours. A viscous mass is formed which is used as an intermediate product OS-2 for further product syntheses.

Example 10 Production of a crosslinked, chemically coupled silicone-PTFE product by cold vulcanization

120 g OS-1 and 40 g dried silane-modified PTFE micropowder PTFE-MP-1 are weighed into a 250 ml three-necked flask with ultra-pure nitrogen gassing/gas supply and toothed disc stirrer (Dispermat), homogenized and intensively mixed at 15,000 rpm. The reaction mixture is heated to 140° C. in an oil bath and stirred intensively for 30 minutes.

After cooling the polydimethylsiloxane-PTFE prepolymer, before crosslinking, a sample is taken and the solubles are removed by extracting 5 times with toluene with stirring at 50°C. Finally, the residue is extracted 5 times with petroleum ether and dried. In addition to the PTFE solid product, polydimethylsiloxane residues could be detected in the difference spectrum by IR spectroscopy, which proves the chemical coupling of polydimethylsiloxane to the silane-modified PTFE before crosslinking.
50 g of the polydimethylsiloxane-PTFE prepolymer and 25 g of Aerosil (fumed silica, Evonik) are mixed in a laboratory kneader at room temperature and at 100 rpm. After 5 minutes, 1.2 g of tetraethoxysilane and 1.1 g of dibutyltin dilaurate are also mixed in. After a further 3 minutes, the mass is removed and formed into a plate between 2 plates at a distance of 10 mm. After 2 hours, this mass had cured to form an elastic silicone rubber-PTFE product. Test specimens were punched from this cross-linked plate and examined in the block/ring test with regard to sliding friction and wear in comparison to a silicone rubber mass without PTFE and with physically mixed PTFE (TF 9205, unirradiated).

The tribological examination of the specimens of the crosslinked silicone rubber mass without PTFE was terminated after a short time without any results.

The specimens of the crosslinked silicone rubber-PTFE (TF 9205) product with physically mixed PTFE (TF 9205, unirradiated) exhibited rough running with a coefficient of friction between 0.35 and 0.60 in the test. After running-in wear, a wear coefficient k ~ 6.0×10 ^-4 mm ³ /Nm was determined. The chemically coupled silicone rubber-PTFE mixture, on the other hand, showed relatively smooth running with a friction coefficient of between 0.30 and 0.40 and a wear coefficient of k ~ 3.5 × 10 ^-5 mm ³ /Nm after a short time in the test.

Example 11 Production of a crosslinked, chemically coupled silicone rubber-PTFE product by hot vulcanization

40 g mass OS-2 are mixed with 20 g Aerosil and 20 g PTFE-MP-2 in a Haake kneader for 5 min at 50 rpm. 2.5 g of bis-2,4-dichlorobenzoyl peroxide paste (as a 50% by weight paste in silicone oil) are then worked in at room temperature. The mixture is pressed in a heatable press with a plate tool to form a plate 10 mm thick and is kept at 110° C. for 30 minutes, during which it crosslinks.

Test specimens were punched from this plate and examined in the block/ring test with regard to sliding friction and wear in comparison to a silicone rubber mass without PTFE and with physically mixed PTFE TF 9205 (unirradiated).

The tribological investigation of the peroxide-crosslinked silicone rubber specimens without PTFE was discontinued after a short time without any results.

The peroxide-crosslinked, physically mixed silicone rubber-PTFE (TF 9205) product exhibited relatively rough running with a coefficient of friction between 0.30 and 0.50 in the test. After running-in wear, a wear coefficient k ~ 2.5×10 ^-4 mm ³ /Nm was determined.

The peroxide-crosslinked, chemically coupled silicone rubber-PTFE mixture showed smooth running with a friction coefficient of between 0.25 and 0.35 and a wear coefficient of k ~ 8.5 × 10 ^-6 mm ³ /Nm after a short time in the test.

Example 12 Production of a crosslinked, chemically coupled silicone rubber-PTFE product by hot vulcanization

Analogously to Example 11, 40 g of mass OS-2 are mixed with 20 g of Aerosil and 20 g of PTFE-MP-4 in a Haake kneader for 5 minutes at 50 rpm. 2.5 g of bis-2,4-dichlorobenzoyl peroxide paste (as a 50% by weight paste in silicone oil) are then worked in at room temperature. The mixture is pressed in a heatable press with a plate tool to form a plate 10 mm thick and is kept at 110° C. for 30 minutes, during which it crosslinks.

Test specimens were punched out of this plate and tested in the block/ring test with regard to sliding friction and wear in comparison to the crosslinked silicone rubber mass with physical mixed PTFE TF 9205 (unirradiated) according to Example 11 examined.

The peroxide-crosslinked, chemically coupled silicone rubber-PTFE mixture showed smooth running with a friction coefficient of between 0.25 and 0.35 and a wear coefficient of k ~ 8.5 × 10 ^-6 mm ³ /Nm after a short time in the test.

Example 13 Production of an electron beam crosslinked, chemically coupled silicone rubber PTFE product

Analogously to Example 11 (but without peroxide as crosslinking agent), 40 g of OS-2 composition are mixed with 20 g of Aerosil and 20 g of PTFE-MP-2 in a Haake kneader for 5 minutes at 50 rpm. The mixture is pressed in a heatable press with a plate tool to form a plate 5 mm thick, which is then irradiated from both sides with 200 kGy by electron beams and is crosslinked in the process.

Test specimens were punched out of this plate and examined in the block/ring test with regard to sliding friction and wear. The electron beam cross-linked, chemically coupled silicone rubber-PTFE mixture showed smooth running with a friction coefficient between 0.23 and 0.30 and a wear coefficient of k ~ 1.5 × 10 ^-7 mm ³ /Nm after a short run-in wear.

Example 14 Production of an electron beam crosslinked, chemically coupled silicone rubber PTFE product

Analogously to Example 13, 40 g of mass OS-2 are mixed with 25 g of Aerosil and 20 g of PTFE-MP-4 in a Haake kneader for 5 minutes at 50 rpm. The mixture is pressed in a heatable press with a plate tool to form a plate 5 mm thick, which is then irradiated from both sides with 250 kGy by electron beams and is crosslinked in the process.

Test specimens were punched out of this plate and examined in the block/ring test with regard to sliding friction and wear. The electron beam cross-linked, chemically coupled silicone rubber-PTFE mixture showed smooth running with a friction coefficient between 0.22 and 0.28 and a wear coefficient of k ~ 1.0 × 10 ^-7 mm ³ /Nm after a short run-in wear.

Example 15 Production of an electron beam crosslinked, chemically coupled silicone rubber PTFE product

Analogously to Example 13, 40 g of mass OS-2 are mixed with 25 g of Aerosil and 20 g of dried, polybutadiene-modified PTFE-MP-6 in a Haake kneader for 5 minutes at 50 rpm. The mixture is pressed in a heatable press with a plate tool to form a plate 5 mm thick and then irradiated with 150 kGy by electron beams from both sides, thereby crosslinking.

Test specimens were punched out of this plate and examined in the block/ring test with regard to sliding friction and wear. The electron beam cross-linked, chemically coupled silicone rubber-PTFE mixture showed smooth running with a friction coefficient between 0.25 and 0.33 and a wear coefficient of k ~ 3.8 × 10 ^-7 mm ³ /Nm after a short run-in wear.

Example 16: Preparation of a Chemically Coupled Silicone Rubber-PTFE Product by Pt-Catalyzed Crosslinking

30 g of dried, siloxane-modified PTFE-MP-3 and 50 g of ^ELASTOSIL® RT 745 (component B) are placed in a 100 ml three-necked flask with ultra-pure nitrogen gas supply/gas supply and toothed disc stirrer (Dispermat) and mixed thoroughly. The substance is degassed in the vacuum rotary evaporator. After that, component B+PTFE-MP-3 is available as a stable dispersion.

30 g Aerosil and 50 g ^ELASTOSIL® RT 745 (component A) are placed in a 100 ml beaker and homogenized using a stirrer to give component A+Aerosil.

50 g of component B+PTFE-MP-3 are placed in a beaker and 50 g of component A+Aerosil are added and mixed intensively using a stirrer. To degas the mass, the mixture is carefully subjected to a vacuum in a desiccator. The reaction mixture is placed between two plates at a distance of 10 mm and cured at 80° C., thereby crosslinking.

Test specimens were punched from this cross-linked plate and examined in the block/ring test with regard to sliding friction and wear in comparison to a silicone rubber mass without PTFE and with physically mixed PTFE (TF 9205, unirradiated).

The tribological examination of the test pieces of the silicone rubber mass without PTFE was terminated after a short time without any results.

The specimens of the crosslinked silicone rubber-PTFE (TF 9205) product with physically mixed PTFE (TF 9205, unirradiated) showed relatively rough running with a coefficient of friction between 0.45 and 0.60 in the test. After running-in wear, a wear coefficient of k~9.2×10 ^-4 mm ³ /Nm was determined.

The crosslinked, chemically coupled silicone rubber-PTFE mixture with PTFE-MP-3, on the other hand, ran more smoothly with a coefficient of friction between 0.30 and 0.45 and a wear coefficient of k ~ 8.5 × 10 ^-5 mm ³ /Nm.

Example 17: Preparation of a Chemically Coupled Silicone Rubber-PTFE Product by Pt-Catalyzed Crosslinking

30 g of dried TMP-modified PTFE-MP-5 and 50 g of ^ELASTOSIL® RT 745 (component B) are placed in a 100 ml three-necked flask with ultra-pure nitrogen gassing/gas supply and toothed disk stirrer (Dispermat) and mixed intensively. The substance is degassed in the vacuum rotary evaporator. After that, component B+PTFE-MP-5 is available as a stable dispersion.

30 g of dried TMP-modified PTFE-MP-5 and 50 g of ^ELASTOSIL® RT 745 (component A) are placed in a second 100 ml three-necked flask with ultra-pure nitrogen gassing/gas supply and toothed disc stirrer (Dispermat) and mixed intensively. The substance is degassed in the vacuum rotary evaporator. After that, the component A+PTFE-MP-5 is available as a stable dispersion.

50 g of component B+PTFE-MP-5 are placed in a beaker and 50 g of component A+PTFE-MP-5 are metered in and mixed intensively using a stirrer. To degas the mass, the mixture is carefully subjected to a vacuum in a desiccator. The reaction mixture is placed between two plates at a distance of 10 mm and cured at 80° C., thereby crosslinking.

Test specimens were punched out of the cross-linked plate and examined in the block/ring test with regard to sliding friction and wear in comparison to a silicone rubber mass with physically mixed PTFE (TF 9205, unirradiated).

The tribological examination of the specimens of the crosslinked silicone rubber-PTFE (TF 9205) product with physically mixed PTFE (TF 9205, unirradiated) showed rough running with a coefficient of friction between 0.35 and 0.60 in the test. After running-in wear, a wear coefficient of k~5.5×10 ^-4 mm ³ /Nm was determined.

The crosslinked, chemically coupled silicone rubber-PTFE mixture with PTFE-MP-5, on the other hand, ran smoothly with a coefficient of friction between 0.25 and 0.35 and a wear coefficient of k ~ 2.8 × 10 ^-5 mm ³ /Nm.

Example 18: Production of a crosslinked, chemically coupled silicone-PTFE product by cold vulcanization

120 g of OS-1 and 40 g of dried PTFE micropowder PTFE-MP-7 (modified with aminopropyltriethoxysilane and APO-128) are introduced into a 250 ml three-necked flask with ultra-pure nitrogen gassing/gas supply and toothed disk stirrer (Dispermat) and at 15,000 rpm intensely mixed. The reaction mixture is heated to 140° C. in an oil bath and stirred intensively for 30 minutes.

After cooling the polydimethylsiloxane-PTFE prepolymer, before crosslinking, a sample is taken and the solubles are removed by extracting 5 times with toluene with stirring at 50°C. Finally, the residue is extracted 5 times with petroleum ether and dried. In addition to the PTFE solid product, polydimethylsiloxane residues could be detected in the difference spectrum by IR spectroscopy, which proves the chemical coupling of polydimethylsiloxane to the PTFE-MP-7 before crosslinking.

50 g of the polydimethylsiloxane-PTFE prepolymer and 25 g of Aerosil (fumed silica, Evonik) are mixed in a laboratory kneader at room temperature and at 100 rpm. After 5 minutes, 1.2 g of tetraethoxysilane and 1.1 g of dibutyltin dilaurate are also mixed in. After a further 3 minutes, the mass is removed and formed into a plate between 2 plates at a distance of 10 mm. After 2 hours, this mass had cured to form an elastic silicone rubber-PTFE product.

Test specimens were punched from this cross-linked plate and examined in the block/ring test with regard to sliding friction and wear in comparison to a silicone rubber mass without PTFE and with physically mixed PTFE (TF 9205, unirradiated).

The tribological examination of the specimens of the crosslinked silicone rubber mass without PTFE was terminated after a short time without any results.

The specimens of the crosslinked silicone rubber-PTFE (TF 9205) product with physically mixed PTFE (TF 9205, unirradiated) exhibited rough running with a coefficient of friction between 0.35 and 0.60 in the test. After running-in wear, a wear coefficient k ~ 6.0×10 ^-4 mm ³ /Nm was determined. The chemically coupled silicone rubber-PTFE mixture with the PTFE-MP-7, on the other hand, showed smooth running with a coefficient of friction between 0.25 and 0.30 and a wear coefficient of k ~ 5.0 × 10 ^-6 mm after a short time in the test ³ /Nm.

Claims (19)

Chemically coupled silicone-PTFE products consisting of silicone, which via a reactive reaction with carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, as functional groups and/or radicals and/or silane and siloxane groups or silane groups and/or olefinic unsaturated compound(s) with at least one olefinically unsaturated double bond of a modified PTFE by substitution and/or addition and/or condensation reactions and/or catalyzed (addition) reactions and/or radical (coupling) reactions before and/or during and /or is chemically coupled via covalent bonds after a crosslinking reaction. Chemically coupled silicone-PTFE products according to claim 1, in which PTFE via the reactive reaction of carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups, as functional groups and/or radicals of the PTFE with the silicone via covalent bonds formed during substitution and/or or addition and/or free radical (coupling) reactions are coupled. Chemically coupled silicone-PTFE products according to claim 1, wherein PTFE is coupled via the reactive reaction of silane groups of the PTFE with the silicone via covalent bonds formed during condensation reactions. Chemically coupled silicone PTFE products claim 1 , in which PTFE is coupled via the reactive conversion of silane groups of the PTFE with the silicone via covalent bonds that have arisen during catalyzed reactions. Chemically coupled silicone PTFE products claim 1 , in which PTFE is coupled via the reactive reaction of olefinically unsaturated groups of and/or on the PTFE with the silicone via covalent bonds that have arisen during radical reactions. Chemically coupled silicone PTFE products claim 1 , in which PTFE is coupled via the reactive conversion of olefinically unsaturated groups of the PTFE with the silicone via covalent bonds that have arisen during catalyzed reactions. Chemically coupled silicone PTFE products claim 1 , in which silicone rubbers and/or silicone elastomers and/or mixtures of these or one another are present as the silicone. Chemically coupled silicone PTFE products claim 1 , in which radiation-chemically and/or plasma-chemically modified PTFE is present. Chemically coupled silicone PTFE products claim 1 , in which the silicone is chemically coupled with modified PTFE via condensation reactions and/or catalyzed reactions and/or radical reactions after the reactive conversion/crosslinking reaction via covalent bonds. Chemically coupled silicone PTFE products claim 1 , in which the silicone with modified PTFE after the reactive reaction by a platinum-catalyzed reaction of Si-H groups with olefinically unsaturated groups to form covalent Si-C bonds or by a condensation reaction of the Si-OR and/or Si-O -COR groups to form covalent Si-O-Si bonds or chemically by a radiation-chemically and/or peroxide-initiated radical reaction of the methyl groups on the silicone/silane and/or the olefinically unsaturated double bonds to form covalent CC bonds on the PTFE and/or silicone is coupled. Chemically coupled silicone PTFE products claim 1 in which the crosslinking reactions of the silicone are a catalyzed reaction with tetraalkyl orthosilicate and/or a radical reaction with one or more peroxides and/or by high-energy rays. Process for the production of chemically coupled silicone-PTFE products according to claim 1 , in which - radiation-chemically modified PTFE powder with carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups and/or with persistent perfluoroalkyl (peroxy) radicals and/or - with at least one silane and at least one siloxane or with at least one silane and or with at least one low molecular weight compound which has no double bond and at least two identical or different functional groups, and/or with at least one monomer which has a double bond and at least one further double bond and/or functional group, and/or with at least one oligomer, which has at least one double bond or functional group and at least one further double bond and/or functional group, and/or with at least one polymer which has at least one double bond or functional group and at least one further double bond and/or functional group, chemically modified PTFE Powder is homogeneously dispersed in silicone/(poly)(organo)siloxane or silicone mixtures and then crosslinked, with the silane and siloxane groups formed on the modified PTFE powder particles before and/or during the homogenization and/or before and/or during the crosslinking or silane groups and/o the carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups as functional groups and/or groups with at least one olefinically unsaturated double bond with the silicone or the silicone mixtures by a reactive reaction via substitution and/or addition and/or condensation reactions and/or Catalyzed reactions and / or radical reactions are coupled chemically via covalent bonds. procedure after claim 12 , in which the PTFE powder has at least one low-molecular compound which, before the coupling to the PTFE, has at least two identical and/or different carbonyl fluoride and/or carboxylic acid and/or perfluoroalkylene groups as functional groups and no olefinically unsaturated double bond, and/ or with at least one monomer that has a double bond and at least one other double bond and/or functional group, and/or oligomer that has at least one double bond or functional group and at least one other olefinically unsaturated double bond and/or one other functional group, and /or polymer that has at least one double bond or functional group and at least one other olefinically unsaturated double bond and/or one other functional group, and/or is modified with at least one silane and siloxane or silane before homogenization and/or crosslinking. procedure after claim 12 , in which silicone starting materials for silicone synthesis and/or silicones and/or silicone mixtures with or without additives and/or fillers and/or reinforcing materials are used as dispersants. procedure after claim 12 , in which the homogenization is carried out using a mixer, kneader, extruder, stirrer or ultrasound. procedure after claim 12 , in which the silicone or silicone mixtures used are silicone rubbers or mixtures thereof or mixtures with one another, also with silicone elastomers. procedure after claim 12 , in which PTFE micropowders are used. procedure after claim 12 , In which the crosslinking of the silicone or silicone mixtures by a catalyzed reaction of Si-H groups with olefinically unsaturated groups of poly (organo) siloxanes and / or on PTFE and / or on, with low molecular weight compounds and / or monomers and / or Oligomers and/or polymers modified PTFE and/or a catalyzed reaction with tetraalkyl orthosilicate and/or a radical reaction with one or more peroxides and/or high-energy rays is realized. Use of a chemically coupled silicone-PTFE product according to any one of Claims 1 until 11 and made according to one of the Claims 12 until 18 as a material for seals in sealing technology or in scraper or wiper technology with tribological requirements.