EP1749054A1

EP1749054A1 - Rubber composition, elastomer, method for producing the same and use of composite particles

Info

Publication number: EP1749054A1
Application number: EP05741671A
Authority: EP
Inventors: Thomas RÜHLE; Dirk Schubert; Achim Gruber; Gregor Grun; Jürgen Henke
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 2004-05-28
Filing date: 2005-05-06
Publication date: 2007-02-07
Also published as: DE102004026685A1; WO2005118704A1; JP2008500412A; US20080014438A1; DE102004026685B4

Abstract

The invention relates to a composition comprising a) rubber, b) a cross-linking agent, c) chalcogenides of metals and/or metals as the cross-linking aids and/or age protecting agent, whereby at least one of the components b) and c) is present as composite particles that are constituted of carrier particles to the surface of which particles from the active material having an average diameter of less than 25 νm or layers thereof having an average layer thickness of less than 25 νm are applied and/or conglomerates from a plurality of carrier particles to the surface of which particles from the active material having an average diameter of less than 25 νm or layers thereof having an average layer thickness of less than 25 νm are applied, and d) optionally additional conventional additives. The inventive composite particles allow to reduce the content in active material while offering comparable properties or to improve the aging resistance of elastomers and/or to increase productivity.

Description

description

Rubber composition, elastomer, process for their production and use of composite particles

The present invention relates to rubber compositions containing selected composite particles, elastomers obtainable therefrom and processes for their production. The use of selected composite particles as a crosslinking agent and / or as a crosslinking aid and / or for protecting aging of elastomers is also described.

When using ultrafine particles in rubbers, the optimal distribution of the particles is very important in order to be able to use their potential as well as possible. By entering mechanical energy, this goal can only be achieved in exceptional cases.

Processes for the production of ultrafine particles on ceramic and carbon-based supports are known from the field of heterogeneous catalysis. As for example with C. Prado-Burguete et al. in Journal of Catalysis 128 (1991) 397-404, by impregnating carbon blacks with hexachloroplatinic acid and then oxidizing them with oxygen and reducing them with hydrogen, depending on the preparation and reaction conditions chosen, ultrafine platinum particles with a diameter of 1 -10 nm can be obtained on the surface. Any previous activation of the carrier usually takes place here under a certain gas atmosphere at elevated temperatures. US Pat. No. 6,146,454 describes a process for producing precipitated silicas which can be used as fillers for improving the rheological properties of elastomers. The precipitated silicas have a zinc content of 1 to 5% by weight, are spherical in shape and are characterized by a number of other physical parameters. As

Fillers are used as spherical silica gels with average diameters of more than 80 μm. The patent does not specify where the zinc is in these particles.

EP-A-475,046 describes a process for producing particles in which zinc oxide and silica are pressed together. The particles obtained have diameters in the micrometer range; It does not include nanoscale components. The fillers do not dust, can be easily conveyed, processed in conventional mixing units and can be easily dispersed in rubber mixtures.

From WO-A-03 / 97,735, inorganic fillers are known which are coated with nanoscale Sn compounds. These are suitable as flame retardants in polymer compositions, including in elastomers.

WO-A-00 / 15,710 describes surface-modified fillers for flame-resistant finishing of polymers, including elastomers. Due to the way in which the fillers are produced, it can be assumed that the modification takes the form of a coating on the surface.

WO-A-01/14480 describes the coating of the surface of nanoparticulate silicas with the combination of a coupling reagent and an organometallic hydrophobizing component. The coated silicas are used as fillers for elastomers. Because of the way in which the fillers are produced, it can also be assumed that the modification takes the form of a coating on the surface. From EP-A-631, 982 silica aggregates are known which are proposed for use as fillers for reinforcing elastomers. There is no information about the morphology of the particles. Due to the method of production, however, it can be assumed that foreign ions may be incorporated into the bulk phase of the silica during the precipitation.

Finally, US Pat. No. 6,121,346 describes rubber mixtures containing a filler with large nanoscale particles fixed on its surface. The filler can be dispersed well in rubber without the nanoscale particles agglomerating. The addition is intended to counteract wear on the treads.

DE 43 07221 A1 describes the use of supported p-dinitrosobenzene (DNB) in elastomer compositions.

US-A-6,121,346 describes the use of fillers made of large particles deposited thereon in elastomer compositions. The use of supported anti-aging agents and / or cross-linking aids is not apparent from this document.

GB-A-1, 073,868 describes the preparation of a reinforcing agent for elastomer compositions. Pellets are made from an intimate mixture of soot and zinc oxide. Alternatively, an intimate mixture of carbon black and a zinc oxide precursor can be used. The carbon black / zinc oxide combinations disclosed in this document are inhomogeneous and there is also no information about layer thicknesses or particle sizes of the zinc oxide.

Starting from this prior art, the present invention is based on the object of a rubber mixture and an elastomer produced therefrom To provide, which has a significantly reduced heavy metal content with comparable mechanical properties.

Another object was to provide a rubber compound and an elastomer made therefrom that would dramatically improve

Has aging behavior with which a mechanical value is achieved, which is not achieved even with a significantly increased degree of filling of classic additives.

Another object was to provide a process for making this elastomer that is easy to perform and that provides reproducible results.

These tasks are solved by using selected supported additives for the rubber composition which have comparatively small amounts of crosslinking agents and / or crosslinking aids and / or antiaging agents on the surface.

The present invention relates to a composition comprising a) rubber, b) crosslinking agent, which is optionally present as a composite particle, which is composed of carrier particles, on the surface of which particles of a crosslinking agent having an average diameter of less than 25 μm are applied and / or of conglomerates from several carrier particles, on the surface of which particles of crosslinking agent with an average diameter of less than 25 μm are applied, c) crosslinking aid and / or antiaging agent which is a chalcogenide of a metal and / or a metal and which is optionally present as a composite particle that builds up is composed of carrier particles, on the surface of which particles of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, with an average diameter of less than 25 μm are applied and / or of conglomerates of several carrier particles, on which n Surface particles of cross-linking aid and / or anti-aging agent containing a chalcogenide Is metal and / or a metal, are applied with an average diameter of less than 25 μm and optionally d) further additives which are customary per se, with the proviso that at least one of components b) or c) is present as composite particles.

In a further embodiment, the invention relates to a composition comprising a) rubber, b) crosslinking agent, which is optionally present as a composite particle, which is composed of carrier particles, on the surface of which a layer of crosslinking agent having an average layer thickness of less than 25 μm is applied and / or from conglomerates of several carrier particles, on the surface of which a layer of crosslinking agent with an average layer thickness of less than 25 μm is applied, c) crosslinking aids and / or antiaging agents, which is a chalcogenide of a metal and / or a metal, and if appropriate is present as a composite particle, which is composed of carrier particles, on the surface of which a layer of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, is applied with an average layer thickness of less than 25 μm and / or Conglomerates of several doors äger particles, on the surface of which a layer of cross-linking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, is applied with an average layer thickness of less than 25 μm and, if appropriate, d) further additives which are customary per se, with the proviso that at least one of components b) or c) is present as composite particles.

Another preferred embodiment of the present invention relates

Compositions comprising the components a), b), c) and optionally d) defined above, components b) and c) being in the form of composite particles and component b) being composed of carrier particles, on the surface of which a layer of crosslinking agent having an average layer thickness of less than 25 μm is applied and / or from conglomerates of several carrier particles the surface of which has a layer of crosslinking agent applied with an average layer thickness of less than 25 μm, and component c) is composed of carrier particles, on the surface of which particles of crosslinking aid and / or antiaging agent, which is a chalcogenide of a metal and / or a metal , are applied with an average diameter of less than 25 μm and / or from conglomerates of several carrier particles, on the surface of which particles of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, with an average diameter of less than 25 μm are applied.

Yet another preferred embodiment of the present invention relates to compositions comprising the components a), b), c) and optionally d) defined above, components b) and c) being in the form of composite particles and component c) being composed of carrier particles on the surface thereof a layer of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, with an average layer thickness of less than 25 μm is applied and / or of conglomerates of several carrier particles, on the surface of which a layer of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, applied with an average layer thickness of less than 25 μm, and component b) is composed of carrier particles, on the surface of which particles of crosslinking agent with an average diameter of less than 25 μm are applied and / or from conglomerates of m Honorary carrier particles, on the surface of which particles of crosslinking agent with an average diameter of less than 25 μm are applied.

Yet another preferred embodiment of the present invention relates to compositions comprising the components a), b), c) and optionally d) defined above, components b) and c) together on one Composite particles are present that are made up of carrier particles, on the surface of which particles of crosslinking agent, crosslinking aid and / or anti-aging agent, each with an average diameter of less than 25 μm, and / or of conglomerates of several carrier particles, on the surface of which particles of crosslinking agent, crosslinking aid and / or anti-aging agents, each with an average diameter of less than 25 μm.

Cross-linking agents, cross-linking aids and anti-aging agents are also referred to below as "active material".

The present invention further relates to a method for producing an elastomer from the rubber composition defined above, comprising the measures: i) compounding the components a), b), c) and optionally d) defined above in a manner known per se, and ii) heating the composition containing components a), b), c) and optionally d) to a temperature and for a period of time in order to bring about the crosslinking of component a).

Component a) used according to the invention can be of any nature as long as it is a rubber.

In the context of this description, rubbers are understood to mean polymers which can be processed into elastomers.

In the context of this description, the term “elastomer” is to be understood as meaning broadly chemically or physically crosslinked polymers which behave steel-elastic under their glass point and which are rubber-elastic at temperatures above their glass point and which therefore do not flow viscously even at high temperatures. Typical glass temperatures of elastomers are at 20 ° C and underneath. The elastomers produced according to the invention are preferably rubber-elastic up to their melting or decomposition temperature or the T _{g of} the hard component in the case of thermoplastic elastomers.

In addition to thermoplastic elastomers, the term “elastomer” includes in particular elastomers that have to be crosslinked in the course of the processing process.

The rubbers used are all known synthetic rubbers and natural rubbers. Typical and at the same time preferred rubbers are acrylate rubber, polyester-urethane rubber, brominated butyl rubber, polybutadiene, chlorinated butyl rubber, chlorinated polyethylene, epichlorohydrin homopolymer, polychloroprene, sulfurized polyethylene, ethylene acrylate rubber, ethylene vinyl acetate. Rubber, epichlorohydrin copolymers, ethylene-propylene rubber (EP (D) M), sulfur-crosslinked or peroxide-crosslinked, polyether-urethane rubber, ethylene-vinyl acetate copolymer, fluorine rubber (FKM), silicone rubbers, such as, for example Fluorosilicone rubbers or vinyl-containing dimethylpolysiloxane, as well as hydrogenated nitrile rubber, butyl rubber, halobutyl rubber, polyoctenamer, polypentenamer, nitrile rubber, natural rubber, thioplastics, polyfluorophosphazenes, polynorbornene, styrene-butadiene-rubber groups, and carboxylate groups Mixtures of one or more of these rubbers.

Thermoplastic elastomers can be widely used. These include the well-known block copolymers (TPE-S, TPE-E, TPE-U, TPE-A) and elastomer alloys (e.g. TPE-V, TPE-O).

Component a) can be used in different forms, for example as granules or in other comminuted form. Component a) can be present as a compact polymer or also in the form of a foam or as a liquid, dissolved or water-emulsified system. All common types of crosslinking agents can be used as component b). These can be low-molecular or high-molecular compounds. Component b) can be used in conventional form in the compositions according to the invention. Component b) is preferably used in the form of the composite particles defined above. At least one of components b) or c) is in the form of composite particles. Composite particles can also be used on which components b) and c) are supported together.

Component b) is typically present in amounts of 0.1 to 150 phr, based on the proportion of crosslinking agent in the mixture according to the invention, preferably in amounts of 2 to 20 phr.

Typical and at the same time preferred crosslinking agents are sulfur, peroxides, bisphenol crosslinking systems, crosslinking resins, such as polymethylolphenol resins, or compounds which also act as crosslinking accelerators. These include, for example, thiurams, guanidines, thiazoles, xanthates, dithiocarbamates, sulfenamides, dithiophosphates, triazine accelerators or quinone dioximes.

Particularly preferred components b) are bisthiocarbamoyl sulfanes of the general formula

wherein R ^{1 is} a covalent bond or a divalent organic radical, preferably an alkylene radical, and R ² , R ³ , R ⁴ and R ⁵ independently of one another

Are hydrogen or organic radicals, preferably alkyl or aryl radicals. In a preferred embodiment, component b) is used in the form of composite particles which are composed of carrier particles, on the surface of which particles of a crosslinking agent having an average diameter of less than 25 μm are applied and / or which are composed of conglomerates of several carrier particles, particles of crosslinking agent with an average diameter of less than 25 μm are applied to the surface thereof.

In a further preferred embodiment, component b) is used in the form of composite particles which are composed of carrier particles, on the surface of which a layer of a crosslinking agent having an average layer thickness of less than 25 μm is applied and / or which are composed of conglomerates of several Carrier particles, on the surface of which a layer of crosslinking agent with an average layer thickness of less than 25 μm is applied.

Any materials can be used as carrier particles for the composite particles used according to the invention. These can have any shape, for example round, ellipsoidal, irregular or in the form of fibers. However, they are fine particles. Their average diameter is below 25 μm, preferably below 10 μm, particularly preferably less than 5 μm, and very particularly preferably from 5 nm to 1 μm (determined by means of electron microscopy). If fibers are used, it is sufficient if they have a small diameter (median) in only one dimension, e.g. of less than 50 μm.

In addition to the use of corpuscular or fibrous carrier particles, conglomerates of such particles can also be used. Conglomerates of carrier particles can take different forms. This can be network-like structures, e.g. to percolation networks made of fibers as

Act carrier materials, on the surface of the individual carrier materials there are nanoscale particles or thin layers of cross-linking aids and / or anti-aging agents.

In particular, these are conglomerates of carrier particles of different structures, such as corposcular and platelet-shaped, in particular lamellar, carrier particles.

The composite particles of component c) and / or component b) used according to the invention can be modified by the application of surface layers, so that their tendency towards agglomeration in the rubber or. Elastomer composition is reduced. However, care must be taken to ensure that the nanoparticulate particles or layers of crosslinking aids and / or anti-aging agents applied to the surface or at least parts of the surface layers thereof remain accessible to the rubber or the elastomer. Additional surface layers can be applied by polymerization, grafting or adsorption of surface-active polymers, it being possible for these substances to be applied both simultaneously with the crosslinking aid and / or anti-aging agent and subsequently.

In a particularly preferred embodiment, the composite particles of component c) and / or component b) used according to the invention are coated with a wax. As a result, the activity of the supported crosslinking aids, anti-aging agents and / or crosslinking agents can be specifically adjusted and allows a defined start or a targeted reaction of the components used. Waxes whose melting points are in the range between 80 and 250 ° C., in particular in the range from 140 to 200 ° C., are preferably used.

The carrier particles can be applied before the application or production of the surface-bound nanoscale particles or the thin surface layers chemical and / or physical methods have been activated, for example by thermal, chemical or mechanical treatment methods, such as tempering in the furnace, treatment with acids or in a ball mill.

Component c) is typically present in amounts of 0.1 to 150 phr, based on the proportion of crosslinking aid or anti-aging agent in the mixture according to the invention, preferably in amounts of 2 to 20 phr.

Component b) or c) which are preferably used are composite particles which are present in the form of individual particles or of conglomerates comprising these individual particles, the individual particles being composed of carrier particles which are coated with a layer of oxidic material with an irregular surface on which the particles are made Cross-linking agents and / or from cross-linking aids and / or anti-aging agents with an average diameter of less than 25 μm are applied.

Another preferred component b) and / or c) are composite particles which are in the form of individual particles or of conglomerates containing these individual particles, the individual particles being composed of carrier particles which are coated with a layer of oxidic material with an irregular surface a layer of crosslinking agent or of crosslinking aid and / or antiaging agent is applied with an average layer thickness of less than 25 μm.

Typical materials from which the carrier particles of component c) and / or component b) consist are carbons or carbon compounds, for example carbon black, graphite or chemically modified graphite; and also oxidic materials of synthetic or natural origin, such as silicates, silicon dioxide or metal oxides, for example aluminum oxide; or other thermally and mechanically resistant ceramic materials, such as silicon nitride, silicon carbide or boron nitride; or metal carbonates, such as calcium carbonate, or metal sulfides or sulfates, such as calcium sulfate, barium sulfate or iron sulfide. Finely divided ceramic materials or organic polymeric materials can also be used as carrier particles. The latter are to be selected so that they can withstand the temperature treatments during the production of the composite particles without significant degradation or decomposition.

Conglomerates of carrier particles of different structure are preferably used, particularly preferably corpuscular and platelet-shaped, in particular corpuscular and lamellar form, preferably corpuscular quartz and lamellar kaolinite.

The two mineral phases of the conglomerate preferably used according to the invention form a loose aggregate. The combination of corpuscular and platelet-shaped structure results in several application-related advantages. These conglomerates can be quickly mixed into the rubber matrix, there are practically no filler clusters, there is little tendency to sedimentation and excellent dispersion behavior, the conglomerates have a high surface activity and the rubber composition has excellent extrusion properties.

The invention therefore also relates to compositions comprising, as component b) and / or as component c), composite particles composed of conglomerates of several different carrier particles which have corpuscular and platelet-shaped, in particular lamellar, form and in which particles of crosslinking aids or Anti-aging agents and / or crosslinking agents with an average diameter of less than 25 μm are applied.

In a further embodiment, the invention relates to compositions comprising, as component b) and / or as component c), composite particles composed of conglomerates of a plurality of different carrier particles which have corpuscular and platelet-shaped form, and in which a layer of crosslinking aid or anti-aging agent and / or crosslinking agent with an average layer thickness of less than 25 μm is applied to the surface of the different carrier particles.

In addition to components b) and / or c), the composite particles used according to the invention can contain further supported particles which differ from components b) and c) and which are adsorbed or otherwise fixed on the surface of the support particles. Or, in addition to the composite particles used according to the invention, which have components b) and / or c), further composite particles can be used which contain particles or layers of component d) which are adsorbed or otherwise fixed on the surface of the carrier particles.

The particles of crosslinking aid or anti-aging agent and / or of crosslinking agent can have any shape, for example round, ellipsoidal or irregular. However, they are finely divided particles with an average diameter of less than 25 μm, preferably less than 1 μm, determined with the aid of electron microscopy, particularly preferably from 0.01 to 0.5 μm. Or they are thin surface layers with an average layer thickness of less than 25 μm, preferably less than 1 μm, determined with the aid of electron microscopy, particularly preferably from 0.01 to 0.5 μm. The particles or layers of crosslinking aid or anti-aging agent and / or of crosslinking agent in the composite particles used according to the invention are significantly smaller than the respective carrier particles. Typically, the ratio of the average diameter of particles of active material to the average diameter of the carrier particle is less than 1: 2, preferably 1:10 to 1: 1000; or the ratio of the average layer thickness of the surface layer made of active material to the average diameter of the carrier particle is less than 1: 2, preferably 1:10 to 1: 1000. It is assumed that the particles of cross-linking aid or anti-aging agent and / or of cross-linking agent are embedded in the pores or depressions of the jagged surface of the conglomerates made of different carrier materials, so that they are freely accessible from the surroundings of the composite particle.

In the case of the thin surface layers, these can cover the entire surface or only a part thereof.

All materials with which a desired property of the elastomer composition can be influenced can be used as further supported materials.

Typically, the further supported material is a material that does not conduct electricity or is semiconducting and / or non-chalcogenide compounds of metals, in particular nitrides or carbides of metals and the other materials listed below for component d).

The metal chalcogenides and / or the metals of component c) can be used in conventional form in the compositions according to the invention. Component c) is preferably used in the form of the composite particles defined above. At least one of components b) or c) is in the form of composite particles. Compositions containing component c) as composite particles or containing components b) and c) as composite particles or compositions containing crosslinking agents and crosslinking aids and / or antiaging agents as particles or layers on a carrier are particularly preferred.

Particles or layers of any chalcogenides of metals and / or of any metals can be used as particles or layers of crosslinking aids and / or anti-aging agents which are adsorbed or otherwise fixed on the surface of the composite particles used according to the invention if they promote the activity of the crosslinking agent and / or the resistance to aging processes in the compositions according to the invention.

It is assumed that the nanoscale particles of crosslinking aids and / or anti-aging agents are only partially embedded in any pores or depressions in the surface of the carrier particles, so that they are freely accessible from the surroundings of the particle composite for the rubber or elastomer matrix.

All metal chalcogenides and / or metals can be used as crosslinking aids, with which activation of the crosslinking agent can be generated or which control or catalyze the crosslinking.

All metal chalcogenides and / or metals with which degradation of the elastomer produced according to the invention can be prevented or slowed down can be used as an anti-aging agent.

Metal oxides, in particular oxides of magnesium, calcium, barium, titanium, manganese, iron, copper, zinc, silver, gold, platinum, zirconium, yttrium, aluminum and tin are preferred.

Metals from the platinum group, in particular platinum, are also preferred.

Magnesium oxide and / or zinc oxide are particularly preferred.

The cross-linking aids or anti-aging agents can exist as binary, ternary and higher systems.

Composite particles in which the carrier particle has an average diameter of 5 nm to 50 μm (D50) and in which the particles consist of crosslinking agent and / or of crosslinking aid are particularly preferably used and / or from anti-aging agents have an average diameter of 1 nm to 25 μm (D ₅₀ ), in particular 10 nm to 5 μm, very particularly preferably 50 nm to 1 μm, with the proviso that the ratio of the average diameter of the carrier particles to the average The diameter of the particles of active material is above 2: 1, preferably between 10: 1 to 100: 1.

Composite particles in which the carrier particle has an average diameter of 5 nm to 50 μm (D ₅₀ ) and a layer of crosslinking agent and / or of crosslinking aid and / or of antiaging agent with an average layer thickness of 1 nm to 25 μm in particular are likewise preferably used 10 nm to 5 μm, very particularly preferably 50 nm to 1 μm, the ratio of the average diameter of the carrier particles to the average layer thickness of the layer of active material being above 2: 1, preferably between 10: 1 to 100: 1.

As additives, the rubber mixtures according to the invention can optionally be added as components d) which impart a desired property to the elastomer and / or which serve as processing aids. Examples of preferred components d) are accelerators, mold release agents, fillers, pigments, flame retardants, antistatic agents, blowing agents, plasticizers, biocides and conventional anti-aging agents.

Preferred biocides are copper, silver, gold and their compounds, especially their oxides.

Component d) can be used in conventional form in the compositions according to the invention. However, it is also possible to use component d) in the form of composite particles which correspond to the composite particles defined above for component b) and / or component c). It can too Composite particles are used on which components b) and d) or c) and d) or b), c) and d) are present together.

The compositions according to the invention can be prepared by processes known per se. Components a), b), c) and optionally d) are usually processed together in mixing units. Examples of mixing units are kneaders, rolling mills or extruders. Mixing can be done dry or wet.

Component b) or c) used according to the invention can be produced in different ways.

The production can be carried out by mechanical processes, for example by grinding the carrier material and crosslinking aid and / or anti-aging agent together and then thermally spreading the crosslinking agent and / or the crosslinking aid and / or antiaging agent on the carrier material. In this variant, the nanoscale particles or layers are generated directly on the surface of the carrier. Another mechanical process is dry coating through high-energy collisions of a powder mixture in a stator / rotor system.

Production by electrostatic charging of carrier material and nanoscale particles from crosslinking agents and / or crosslinking aids and / or anti-aging agents is also suitable, so that a carrier via Coulomb forces is produced.

Component b) or c) can also be produced by pyrogenic gas phase processes and by plasma processes. Another preferred production method for composite particles of component b) and / or c) consists in coating the carrier material with a suitable thermolabile substance. The layer of the thermolabile substance is then thermally treated, so that the decomposition of this thermolabile substance while maintaining the layer increases the surface of the coated carrier, and then the ultrafine particles or layers of crosslinking agent and / or of crosslinking aid and / or anti-aging agent applied to the enlarged surface.

Instead of this procedure, the carrier material can be coated with a suitable thermolabile substance and then ultrafine particles or thin layers or suitable precursors for ultrafine particles or thin layers are applied in a suitable manner to the surface of the coating. This is followed by a thermal treatment in order to decompose the thermolabile substance while maintaining the layer to enlarge the surface and to produce the particles or thin layers of crosslinking agent and / or of crosslinking aid and / or anti-aging agent from the adsorbed precursor substances.

The materials described above can be selected as carrier materials. These carrier materials must be in a fine distribution.

Carrier materials and thermolabile substances are to be selected in individual cases so that the dimensions of the carrier material do not change or change less than 5% at the required temperature of the thermal treatment.

Any silicon, aluminum, alkaline earth or alkali-containing compounds which have at least one organic radical, preferably an alkyl radical, which is partially or completely halogenated can be used as the thermolabile substances for producing a layer of oxidic material with an irregular surface covering the carrier particles may contain. Examples of thermolabile substances are silanes or silicon halogen compounds which contain at least one organic radical, such as aliphatic radicals, including the ethylenically unsaturated aliphatic radicals, aromatic radicals and / or carboxyl radicals, or organoaluminum compounds, such as trialkylaluminum, dialkylaluminium halides or alkylaluminum dihalides; or alkaline earth organic compounds such as dialkyl calcium or alkyl calcium chloride; or alkali-organic compounds, such as alkyl lithium, alkyl sodium or alkyl potassium, organic sandwich compounds (metallocenes) or metal carbonyls and mixtures thereof.

Targeted thermal treatment is used to create a layer of oxidic materials from the thermolabile substances, which is characterized by a strong fissuring of the surface. In addition to an already existing irregular surface of the carrier particles, this leads to an increase in the surface of the particles. This manifests itself in an increase in the specific surface area after the thermal treatment of the carrier particles coated with precursor substance.

As a rule, the specific surface area (determined according to the BET method) increases by at least 10%, preferably by at least 25%, by the thermal treatment. Without being bound by theoretical considerations, it is assumed that the decomposition of the organic residues of the thermolabile substance (s) creates pores and / or sinks in the outer layer, on or in which the ultrafine particles or thin layers of crosslinking agent and / or accumulate from cross-linking aids and / or anti-aging agents. As a result of the arrangement of these particles on the surface or the use of thin surface layers, it is possible to lower the content of active component and still obtain the desired effects, for example catalytic or stabilizing properties. In the context of this description, “irregular surface” is understood to mean a surface that deviates from the shape of an ideal spherical surface or the ideal surface of another rotationally symmetrical shape. Without being bound by theoretical considerations, this can be illustrated using the following model a regular spherical surface, all small hemispheres with a radius that is significantly smaller than the radius of the large sphere, so that a surface similar to a golf ball is created, so the surface can theoretically be at least 1.8 times the constant radius of the sphere increase.

The surfaces produced of the material of this preferred component b) and / or c) used according to the invention are very fissured, i.e. they have pores and / or depressions which arise from the shrinkage of the thermally unstable precursor substance (calcination).

The thermolabile substances are applied to the surface of the carrier material by methods known per se. Examples of this are the impregnation of the surface of the carrier material with the thermolabile substance or a mixture of thermolabile substances or the direct application of thermolabile substances on the carrier material by simply mixing both components. The thickness of the resulting layer can be adjusted in a known manner via the concentration in the impregnation solution or impregnation suspension or emulsion and also the surfactants. Typical layer thicknesses of the layer of thermolabile substance on the carrier material are in the range from 1 to 1000 nm.

The layer can be formed by equilibrium adsorption. The carrier materials are suspended in a solution, suspension or emulsion of thermolabile substances and the loading of the carrier materials is controlled via the concentration offered, the optimum of which is determined, for example, from an adsorption isotherm. Another layer formation method is the so-called "Incipient Wettness" method. Here, a paste-like mass is produced from the carrier material together with the solution, suspension or emulsion of the precursor substance of the active phase and the thermolabile substance. The loading can be controlled via the amount of the thermolabile substance contained in the solution, suspension or emulsion and can optionally be increased by repeated repetition.

The coated carrier material is then dried in air. Typical drying times are at least six, preferably at least twelve hours. The drying temperature is selected between 50 and 150 ° C depending on the thermal stability of the adsorbed substance.

The thermolabile substance can be adsorbed on the surface of the carrier material or can also be covalently bonded to the surface, for example by using alkyl silicon halogen compounds.

The thermolabile substance can advantageously be applied by impregnating the carrier material with a solution in an organic solvent or preferably in water.

The thermal treatment is usually carried out in air or under an artificial oxygen-containing atmosphere. The treatment time should be selected to be sufficiently long to generate the enlarged surface phase from the adsorbed thermolabile substances. Typical treatment times are more than six, preferably more than twelve hours, in particular twelve to twenty-four hours. The choice of temperatures depends on the type of thermolabile material and the atmosphere used. The temperature should be selected so that the treatment results in at least partial decomposition of the thermolabile substance. As a rule, the organic residues are decomposed and cavities and fissures form on the surface of the layer made of thermolabile material. At the same time, the material of this layer is oxidized. The layer changes, but remains as a closed or non-closed layer. Typical treatment temperatures range from 150 to 500 ° C.

The progress of the enlargement of the surface can be followed by determining the specific surface of the coated carrier material by methods known per se. An example of such a method is the determination according to B.E.T. (Journ. Americ. Chem. Soc, Vol. 60, 309, Feb. 1938).

Surprisingly, the thermal treatment does not reduce the surface area but increases it. It is assumed that the effect of the homogenization of the particle surface caused by the thermal treatment is more than compensated for by the partial decomposition of the thermolabile substance.

After the thermal treatment of the layer of thermolabile substance or alternatively after the application of this layer to the carrier material and before the thermal treatment of the layer of thermolabile material, the coated carrier material is coated with ultrafine particles and / or precursors for ultrafine particles from crosslinking agent and / or from crosslinking aid and / or anti-aging agents. These settle on the surface of the layer of thermolabile substance or on the layer that has already been thermally treated. Instead of applying ultrafine particles, larger amounts of crosslinking agent and / or can be applied by applying

Cross-linking aids and / or anti-aging agents produce thin surface layers.

The substances described above or their precursors can be selected as crosslinking agents and / or as crosslinking aids or anti-aging agents. Carrier materials, thermolabile substances and active materials or their precursors are to be selected in such a way that the dimensions of the carrier material and the active material do not change or change less than 5% at the required temperature of the thermal treatment and that the thermolabile substance and the precursor of the active material change change the temperature of the thermal treatment. The active material can be generated either simultaneously with the decomposition of the thermolabile substance or after its decomposition.

The active material or its precursor can also be applied to the surface of the optionally coated carrier material by methods known per se. Examples of this are the methods already described in the description of the application of the thermolabile substance to the surface of the carrier material, that is to say direct application or impregnation.

Here, too, the impregnation can be carried out by application from solution, suspension or emulsion or by the "Incipient Wettness" method.

Examples of impregnation solutions containing precursors of particles or layers of active material are 0.1 molar to saturated metal salt solutions, for example zinc, magnesium, titanium, calcium, iron and / or

Barium salt solutions, the salts used preferably being hydroxides, carbonates, carboxylic acid salts, chlorides, sulfates, acetylacetonates and / or nitrates. The pH of the impregnation solution is adapted to the coated carrier particle used in each case in such a way that the adsorption of the precursor substance on the optionally coated carrier particle is optimized.

The amount of material applied can be adjusted via the concentration in the impregnation solution or impregnation suspension or emulsion and also the surfactants. The formation of a closed layer of active

Material is not essential as the ultrafine particles are made of active Should deposit material on the surface of the carrier material, optionally coated with organic or organosilicon compounds.

The amount of active material, that is to say crosslinking agent and / or crosslinking aid and / or anti-aging agent, is typically selected so that composite particles with a loading of 1 to 50% by weight, preferably 5 to 30% by weight, of active material result.

The active material can already be applied in the desired particle shape and distribution to the surface of the optionally coated carrier material, or the ultrafine particles or layers of active material can be produced on this surface by thermal treatment.

Treatment times, composition of the treatment atmosphere and treatment temperatures should be selected so that the desired active material results from the corresponding precursor. The adsorbed molecules begin to become mobile and agglomerate on the surface at sufficiently high temperatures. In this way, ever larger supramolecular units are created, which eventually lead to ultrafine particles or, in the presence of higher concentrations, to thin surface layers.

The optionally coated carrier material treated with active material and / or with its precursor is then dried in air. Typical drying times are at least six, preferably at least twelve hours. The drying temperature is chosen between 50 and 150 ° C depending on the thermal stability of the adsorbed substances.

The ultrafine particles or layers of active material are usually adsorbed onto the surface of the optionally coated carrier material, depending on the nature and pH of the carrier and the ultrafine particles via van der Waals interaction (physisorption), via ionic interaction (Coulomb Interaction), preferably via covalent bonds (chemisorption, optionally via organic spacer molecules).

The precursors for ultrafine particles or layers of active material are usually also adsorbed on the surface of the optionally coated carrier material. The desired ultrafine particles or layers of active material are formed from these precursors by thermal treatment. It is believed that supramolecular units are formed from active material, as described above. The occupancy of the surface of the coated carrier material with active material can be controlled by the degree of loading with the active phase.

The thermal treatment is usually carried out in air or under an artificial oxygen-containing atmosphere. The treatment time should be selected to be long enough to generate ultrafine particles or layers of the desired material from the adsorbed precursors of active material.

If the adsorbed substance is a precursor that still has to be converted into the active phase, the material is thermally treated at the decomposition temperature of the precursor, if appropriate under an appropriate gas atmosphere. The optimization of the reaction conditions is carried out by the person skilled in the art on the basis of routine considerations, results from thermal analysis, preferably calorimetry and thermogravimetry, being used.

Typical treatment times are more than six, preferably more than twelve hours, in particular twelve to twenty-four hours. The selection of temperatures depends on the type of precursor substance and the atmosphere used. The temperature should be selected so that the treatment results in the formation of ultrafine particles or layers of active substance. Typical treatment temperatures range from 200 to 500 ° C. The size range of the particles or layers of active material produced from precursor substances can be controlled via the amount of precursor substance applied to the surface of the optionally coated carrier particles. Further process parameters are the temperature selected in the individual case and, if appropriate, the composition of the atmosphere present during the treatment, for example its oxygen concentration and / or its water vapor content. Using the described methods, particles in the size range from 1 nm to 25 μm or layers with layer thicknesses of up to 25 μm are applied to the surface or generated on the surface. The particles or layers are adsorbed on the surface and firmly anchored to the underlying carrier. By means of this fixed fixation, the particles or layers of crosslinking aids and / or anti-aging agents and / or of

, Do not agglomerate crosslinking agents so that their surface is almost 100% accessible. As a result, the inaccessible volume fraction, which is inside the particles of conventional materials, can be reduced to a minimum in terms of sustainable development.

Materials produced in this way with a typical loading of 1 to 50% by weight of the active phase can extraordinarily reduce the content or consumption of active material down to diameters or layer thicknesses of 1 nm due to their extremely fine distribution of the active phase.

Furthermore, the heavy metal content in elastomers can be reduced by up to a factor of ten, the aging behavior even under the influence of temperature can be drastically improved and a mechanical value can be achieved that is not achieved even with a significantly increased degree of filling of classic additives. The use of the supported component b) and / or c) in elastomer compositions is primarily desirable from the point of view of environmental protection, but also in the sense of saving material and thus sustainable development and in the sense of more homogeneous materials. Furthermore, effects can be achieved with ultrafine active materials that are not accessible with classic active materials, because one runs into saturation there for the mechanical properties depending on the concentration, which is not necessarily the case for ultrafine additives. In addition, the additives used according to the invention can be used to formulate systems which can lead to increased productivity.

In addition, the size dependence of certain effects is not only quantitative, but also qualitative in nature, an effect which is known from heterogeneous catalysis with the term "structure sensitivity". For example, ultrafine crosslinking agents and / or crosslinking aids and / or anti-aging agents in rubber matrices usually cannot develop their full potential because they already exist as agglomerates or agglomerate during the mixing process. The solution to circumventing this problem is to transfer the principle of producing heterogeneous catalysts to crosslinking agents and / or crosslinking aids and / or antiaging agents for rubbers or elastomers. The ultrafine particles are not applied in the mixing process, but are applied to larger fillers that are already contained in the rubber or elastomer.

The invention also relates to the use of component c) defined above as a crosslinking aid and / or as an anti-aging agent for rubbers and / or elastomers.

The invention further relates to the use of the supported component b) defined above as a crosslinking agent for elastomers.

The following examples illustrate the invention without limiting it. A 2-molar zinc acetate solution was adjusted to pH 5 and soot was impregnated using the "incipient wettness" process in such a way that a loading of 40% by weight of ZnO was obtained. The paste thus obtained was dried at 100 ° C. for at least 8 hours, then calcined in air at 200 ° C for 12 hours and at 250 ° C for 2 hours.

The material was introduced into a sulfur-crosslinking rubber mixture, with corresponding amounts of original modified support material and the conventional zinc oxide (μ-scale) originally present in the mixture being removed from the mixture, so that the filler content remained constant, the content of crosslinking aid or anti-aging agent ZnO was reduced.

The mechanical values remained at a similar level after 28 days except for the elongation at break despite the significantly reduced ZnO content, and the elongation at break was even 35% better after 28 days of aging. The test results of a conventional elastomer and of the inventive elastomer described above are shown in the table below.

Claims

claims

1. Composition comprising a) rubber, b) crosslinking agent, which is optionally present as a composite particle, which is composed of carrier particles, on the surface of which particles of a crosslinking agent having an average diameter of less than 25 μm are applied and / or of conglomerates of several carrier particles , on the surface of which particles of crosslinking agent with an average diameter of less than 25 μm are applied, c) crosslinking aid and / or anti-aging agent which is a chalcogenide of a metal and / or a metal and which is optionally present as a composite particle which is composed of carrier particles , on the surface of which particles of a crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, with an average diameter of less than 25 μm are applied, and / or of conglomerates of several carrier particles, on the surface of which particles are made of Vern Settlement aids and / or anti-aging agents, which is a chalcogenide of a metal and / or a metal, are applied with an average diameter of less than 25 μm, and d) if necessary, other conventional additives, with the proviso that at least one of the components b ) or c) is present as a composite particle.

2. Composition comprising a) rubber, b) crosslinking agent, which is optionally present as a composite particle, which is composed of carrier particles, on the surface of which particles of crosslinking agent having an average diameter of less than 25 μm are applied and / or of conglomerates of several Carrier particles, on the surface of which particles of crosslinking agent with an average diameter of less than 25 μm are applied, c) crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal and which is optionally present as a composite particle which is composed of Carrier particles, on the surface of which a layer of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, with an average layer thickness of less than 25 μm, and / or of conglomerates of several carrier particles, on the surface of which a Layer of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, is applied with an average layer thickness of less than 25 μm, and d) if necessary, further conventional additives, with the proviso that at least one of the Components b) or c) as a composite particle is present.

3. Composition comprising a) rubber, b) crosslinking agent, which is present as a composite particle, which is composed of carrier particles, on the surface of which a layer of crosslinking agent with an average layer thickness of less than 25 μm is applied and / or of conglomerates of several carrier particles, a layer of crosslinking agent with an average layer thickness of less than 25 μm is applied to the surface thereof, c) crosslinking aid and / or antiaging agent, which is a chalcogenide of a metal and / or a metal and which is present as a composite particle which is composed of carrier particles the surface of which particles of crosslinking aids and / or antiaging agents, which is a chalcogenide of a metal and / or a metal, with an average diameter of less than 25 μm are applied and / or of conglomerates a plurality of carrier particles, on the surface of which particles of crosslinking aid and / or antiaging agent, which is a chalcogenide of a metal and / or a metal, with an average diameter of less than 25 μm are applied, and d) optionally further additives which are customary per se.

4. Composition comprising a) rubber, b) crosslinking agent, which is present as a composite particle, which is composed of carrier particles, on the surface of which particles of crosslinking agent having an average diameter of less than 25 μm are applied and / or of conglomerates composed of a plurality of carrier particles whose surface particles of crosslinking agent with an average diameter of less than 25 microns are applied, c) crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal and which is present as a composite particle, which is composed of carrier particles on the Surface a layer of crosslinking aid and / or anti-aging agent, which is a chalcogenide of a metal and / or a metal, is applied with an average layer thickness of less than 25 microns and / or conglomerates of several carrier particles, on the surface of which is a layer of crosslinking aid and / or alteration gsschutzmittel, which is a chalcogenide of a metal and / or a metal, applied with an average layer thickness of less than 25 microns, and d) if necessary, other conventional additives.

5. Composition comprising a) rubber, b) crosslinking agent, c) crosslinking aid and / or antiaging agent which is a chalcogenide of a metal and / or a metal, and d) if necessary, further additives which are customary per se, with the proviso that components b) and c) are present together on a composite particle which is composed of carrier particles, on the surface of which particles of crosslinking agent, crosslinking aid and / or anti-aging agent, each with an average diameter of less than 25 μm are applied and / or from conglomerates of several carrier particles, on the surface of which particles of crosslinking agent, crosslinking aid and / or anti-aging agent, each with an average diameter of less than 25 μm, are applied.

6. Composition according to one of claims 1 to 5, characterized in that the rubber is synthetic or natural rubber, preferably acrylate rubber, polyester-urethane rubber, brominated butyl rubber, polybutadiene, chlorinated butyl rubber , chlorinated polyethylene, epichlorohydrin homopolymer, polychloroprene, sulfurized polyethylene, ethylene-acrylate rubber, ethylene-vinyl acetate rubber, epichlorohydrin copolymers, ethylene-propylene rubber (EP (D) M), sulfur-crosslinked or peroxide-crosslinked, polyether-urethane Rubber, ethylene-vinyl acetate copolymer, fluorine rubber (FKM), silicone rubbers, such as Fluorosilicone rubbers or vinyl-containing dimethylpolysiloxane, as well as hydrogenated nitrile rubber, butyl rubber, halobutyl rubber, polyoctenamer, polypentenamer, nitrile rubber, natural rubber, thioplastics, polyfluorophosphazene, polynorbornene, styrene-butadiene-rubber group, and carboxylate-rubber group Mixtures of one or more of these rubbers.

7. Composition according to one of claims 1 to 5, characterized in that the rubber is a thermoplastic elastomer, in particular block copolymers (TPE-S, TPE-E, TPE-U, TPE-A) and elastomer alloys (eg TPE-V, TPE-O).

8. Composition according to one of claims 1 to 5, characterized in that component b) is sulfur, peroxides, bisphenol crosslinking systems, crosslinking resins, in particular polymethylolphenol resins, or compounds which also act as crosslinking accelerators

9. The composition according to claim 8, characterized in that component b) is thiurams, guanidines, thiazoles, xanthates, dithiocarbamates, sulfenamides, dithiophosphates, triazine accelerators or quinone dioximes.

10. The composition according to claim 9, characterized in that component b) is a bisthiocarbamoylsulfan of the general formula

in which R ^{1 is} a covalent bond or a divalent organic radical, preferably an alkylene radical, and R ² , R ³ , R ⁴ and R ^{5 are} independently hydrogen and / or organic radicals, preferably alkyl or aryl radicals.

11.Composition according to claim 1, characterized in that component b) is used in the form of composite particles which are composed of carrier particles, on the surface of which particles of a crosslinking agent having an average diameter of less than 25 μm are applied and / or which are constructed are made of conglomerates of several carrier particles, on the surface of which particles of crosslinking agent with an average diameter of less than 25 μm are applied.

^ .Composition according to claim 2, characterized in that component b) is used in the form of composite particles which are composed of carrier particles, on the surface of which a layer of a crosslinking agent with an average layer thickness of less than 25 microns is applied and / or are made up of conglomerates of several carrier particles, on the surface of which a layer of crosslinking agent with an average layer thickness of less than 25 μm is applied.

13. The composition according to claim 1, characterized in that the composite particles are in the form of individual particles or conglomerates containing these individual particles, wherein the individual particles are composed of carrier particles which are coated with a layer of oxidic material with an irregular surface on which particles Cross-linking agents and / or from cross-linking aids and / or anti-aging agents with an average diameter of less than 25 μm are applied.

14. The composition according to claim 2, characterized in that the composite particles are in the form of individual particles or conglomerates containing these individual particles, the individual particles being composed of carrier particles which are coated with a layer of oxidic material with an irregular surface on which a layer from crosslinking agent and / or from crosslinking aid and / or anti-aging agent with an average layer thickness of less than 25 μm is applied.

15. The composition according to any one of claims 1 to 5, characterized in that the carrier particles of component b) and / or c) have an average diameter of less than 5 microns.

16. Composition according to one of claims 1 to 5, characterized in that the carrier particles are carbon, preferably thermal carbon black or flame black, or oxidic carriers, preferably precipitated and / or pyrogenic silicas, or inorganic carbonates, sulfides, sulfates, phosphates, natural fillers, in particular bentonites, nitrates or pigments.

^ .Composition according to one of claims 11 or 1, characterized in that the carrier particles are carbon, preferably thermal soot or flame black, or oxidic carriers, preferably precipitated and / or pyrogenic silicas, or inorganic carbonates, sulfides, Sulphates, phosphates, natural fillers, especially bentonites, nitrates or pigments.

18. Composition according to one of claims 1 to 5, characterized in that the crosslinking aid and / or anti-aging agent is a metal oxide or a mixture of metal oxides.

19. The composition according to claim 18, characterized in that the metal oxide is selected from the group consisting of the oxides of magnesium, calcium, barium, titanium, manganese, iron, copper, zinc, silver, gold, platinum, zirconium, yttrium, aluminum and tin.

20. The composition according to claim 19, characterized in that the metal oxide is magnesium oxide and / or zinc oxide.

21.Composition according to one of claims 1 to 5, characterized in that the crosslinking aid and / or anti-aging agent is a metal, preferably a platinum group metal, in particular platinum.

22. The composition according to claim 1, characterized in that the carrier particle has an average diameter of 5 nm to 50 microns (D ₅ o) and that the particles of crosslinking agent and / or Crosslinking aids and / or anti-aging agents have an average diameter of 1 nm to 25 μm (D ₅₀ ) and that the ratio of the average diameter of the carrier particles to the average diameter of the particles of active material is above 2: 1, preferably between 10: 1 to 100: 1.

23. The composition according to claim 2, characterized in that the carrier particles have an average diameter of 5 nm to 50 microns (D ₅ o) and in that the layer of cross-linking agent and / or crosslinking agents and / or aging inhibitors have an average layer thickness of 1 nm to 25 microns and that the ratio of the average diameter of the carrier particles to the average layer thickness of the layer of active material is above 2: 1, preferably between 10: 1 to 100: 1.

24. The composition according to any one of claims 1 to 5, characterized in that it contains composite particles with conglomerates of several different carrier particles, the carrier particles having corpuscular and platelet-shaped, in particular lamellar form, preferably corpuscular quartz and lamellar kaolinite, and in which on the Surfaces of the different carrier particles particles of crosslinking agent and / or of anti-aging agent and / or crosslinking aid with an average diameter of less than 25 μm are applied or and in each case a layer of crosslinking agent or of anti-aging agent and / or on the surface of the different carrier particles or crosslinking aid is applied with an average layer thickness of less than 25 μm.

25. The composition according to claim 24, characterized in that in each case particles of magnesium oxide and / or zinc oxide with an average diameter of 1 nm to 25 μm are applied to the surface of the different carrier particles or that on the surface of the different Carrier particles each have layers of magnesium oxide and / or zinc oxide applied with an average layer thickness of 1 nm to 25 μm.

26. Composition according to one of claims 1 to 5, characterized in that the composite particles b) and / or c) are coated with a wax.

27. The composition according to any one of claims 1 to 5, characterized in that this component contains c) as composite particles or components b) and c) as composite particles.

28. A method for producing an elastomer from the composition according to claims 1 to 5, comprising the measures: i) compounding components a), b), c) and optionally d) according to claim 1 or 2 in a manner known per se, and ii) Heating the composition containing components a), b), c) and optionally d) to a temperature and for a period of time in order to bring about the crosslinking of component a).

29. Elastomer obtainable by crosslinking the composition according to one of claims 1 to 5.

30. Use of composite particles of component c) according to any one of claims 1 to 5 as a crosslinking aid for rubbers and / or as an anti-aging agent in elastomers.

31. Use of composite particles of component b) according to one of claims 1 to 5 as crosslinking agents for elastomers.