WO2008043481A1

WO2008043481A1 - Gliding material for winter sports equipment

Info

Publication number: WO2008043481A1
Application number: PCT/EP2007/008633
Authority: WO
Inventors: Norbert Schmitt; Karin Maierhofer
Original assignee: Clariant International Ltd
Priority date: 2006-10-06
Filing date: 2007-10-01
Publication date: 2008-04-17
Also published as: DE102006047302A1

Abstract

The invention relates to gliding material for winter sports equipment, preferably ski waxes, which contain nanocorundum to improve tribologic characteristics, said nanocorundum being preferably modified on the surface with a silane or siloxane.

Description

description

Lubricant for winter sports equipment

From WO 2005/095 533 it is known to use hydrophobized silica as an additive for improving the tribological properties in lubricants for winter sports equipment.

It has now been found that the tribological properties of lubricants for winter sports equipment can also be improved by the addition of nanocorundum.

The invention thus relates to a lubricant for winter sports equipment containing nanocorundum, this nanocorner preferably being modified with a silane or siloxane on the surface.

The nanocorundum according to the present invention are nanoparticles consisting of pure aluminum oxide, the alumina being present for the most part in the rhombohedral α-modification (corundum). But there are also nanoparticles in question, which consist of 50 to 99.9 wt .-% Al ₂ O ₃ and 0.1 to 50 wt .-% of an oxide of the I or II. Main group of the Periodic Table. Also in these mixed oxides, the aluminum chloride is present for the most part in the rhombohedral α-modification. The oxides according to the present invention preferably have a crystallite size of less than 1 μm, preferably less than 0.2 μm and particularly preferably between 0.001 and 0.09 μm. Particles of this size will be referred to below as nanoparticles.

Such nanoparticles can be prepared by different methods described below. These process descriptions refer to the production of pure alumina particles, but it goes without saying that in all these process variants in addition to Al-containing starting compounds and those compounds of elements of I. or II. Main group of the Periodic Table can be present to form mixed oxides. For this purpose, especially the chlorides, but also the oxides, oxychlorides, carbonates, sulfates or other suitable salts come into question. The amount of such oxide formers is such that the finished nanoparticles contain the aforementioned amounts of oxide MeO, if such mixed oxides are desired.

In general, the preparation of the nanoparticles according to the invention starts from larger agglomerates which are subsequently deagglomerated to the desired particle size. These agglomerates can be prepared by methods described below.

Such agglomerates can be prepared, for example, by various chemical syntheses. These are usually precipitation reactions (hydroxide precipitation, hydrolysis of organometallic compounds) with subsequent calcination. Crystallization seeds are often added to reduce the transition temperature to the α-alumina. The sols thus obtained are dried and thereby converted into a gel. The further calcination then takes place at temperatures between 35O ⁰ C and 650 ⁰ C. For the conversion to α-Al ₂ O ₃ must then be annealed at temperatures around 1000 ⁰ C. The processes are described in detail in DE 199 22 492.

Another way is the aerosol process. The desired molecules are obtained from chemical reactions of a Precursorgases or by rapid cooling of a supersaturated gas. The formation of the particles occurs either by collision or the constant equilibrium evaporation and condensation of molecular clusters. The newly formed particles grow by further collision with product molecules (condensation) and / or particles (coagulation). If the coagulation rate is greater than that of the new growth or growth, agglomerates of spherical primary particles are formed.

Flame reactors represent a production variant based on this principle. Nanoparticles are produced here by the decomposition of Precursor molecules formed in the flame at 1500 ⁰ C - 2500 ⁰ C. As examples, the oxidations of TiCl ₄ ; SICI ₄ and Si ₂ O (CH ₃ ) ₆ in methane / O ₂ flames leading to TiO ₂ and SiO ₂ particles. When using AICI3 so far only the corresponding clay could be produced. Flame reactors are now used industrially for the synthesis of submicroparticles such as carbon black, pigment TiO ₂ , silica and alumina.

Small particles can also be formed from drops with the help of centrifugal force, compressed air, sound, ultrasound and other methods. The drops are then converted into powder by direct pyrolysis or by in situ reactions with other gases. As known methods, the spray and freeze drying should be mentioned. In spray pyrolysis, precursor drops are transported through a high temperature field (flame, oven), resulting in rapid evaporation of the volatile component or initiating the decomposition reaction to the desired product. The desired particles are collected in filters. As an example, the production of BaTiO ₃ from an aqueous solution of barium acetate and titanium lactate can be mentioned here.

By grinding can also be attempted to crush corundum and thereby produce crystallites in the nano range. The best grinding results can be achieved with stirred ball mills in a wet grinding. In this case, grinding beads must be used from a material that has a greater hardness than corundum.

Another way to produce corundum at low temperature is the conversion of aluminum chlorohydrate. This is also to seed with added, preferably from Feinstkorund or hematite. To avoid crystal growth, the samples must be calcined at temperatures around 700 ⁰ C to a maximum of 900 ⁰ C. The duration of the calcination is at least four hours. Disadvantage of this method is therefore the big one

Time and the residual amounts of chlorine in the alumina. The method has been described in detail in Ber. DKG 74 (1997) no. 11/12, p. 719-722. From these agglomerates, the nanoparticles must be released. This is preferably done by grinding or by treatment with ultrasound. According to the invention, this deagglomeration takes place in the presence of a solvent. The nanocorund remains as a small particle. If, according to the preferred variant, the nanocorund is to be coated on the surface with a silane or siloxane, this coating agent is added during or after the grinding to the suspension of the nanocorundum, the first variant being preferred. By adding such a coating agent during the milling process, the resulting active and reactive surfaces of the nanocorundum are saturated by chemical reaction or by physical attachment and thus prevents reagglomeration of the nanoparticles.

Preferably, in the production of the nanocorundum, agglomerates are used which, as described in Ber. DKG 74 (1997) no. 11/12, pp. 719-722, as previously described.

The starting point here is aluminum chlorohydrate, which has the formula Al ₂ (OH) _x Cl y, where x is a number from 2.5 to 5.5 and y is a number from 3.5 to 0.5 and the sum of x and y is always 6 amounts to. This aluminum chlorohydrate is mixed with crystallization seeds as an aqueous solution, then dried and then subjected to a thermal treatment (calcination).

Preference is given to starting from about 50% aqueous solutions, as they are commercially available. Such a solution is mixed with nuclei which promote the formation of the α-modification of Al ₂ O ₃ . In particular, such nuclei cause a lowering of the temperature for the formation of the α-modification in the subsequent thermal treatment. As germs are preferably in question finely disperse corundum, diaspore or hematite. Particular preference is given to using finely divided α-Al ₂ O ₃ nuclei having an average particle size of less than 0.1 μm. In general, 2 to 3 wt .-% of germs based on the resulting alumina from. If necessary, this starting solution still contains oxide formers in order to generate the oxides MeO in the nanocorundum. For this purpose, especially the chlorides of the elements of the I. and II. Main group of the Periodic Table, in particular the chlorides of the elements Ca and Mg, but also other soluble or dispersible salts such as oxides, oxychlorides, carbonates or sulfates. The amount of oxide generator is such that the finished nanoparticles contain 0.01 to 50 wt .-% of the oxide MeO. The oxides of the I. and II. Main group may be present as a separate phase in addition to the alumina or with this real mixed oxides such as spinels, etc. form. The term "mixed oxides" in the context of this invention should be understood to include both types.

This suspension of aluminum chlorohydrate, germs and optionally oxide formers is then evaporated to dryness and subjected to a thermal treatment (calcination). This calcination is carried out in suitable devices, for example in push-through, chamber, tube, rotary kiln or microwave ovens or in a fluidized bed reactor. According to a variant of the process according to the invention, it is also possible to inject the aqueous suspension of aluminum chlorohydrate, germs and optionally oxide formers directly into the calcining apparatus without prior removal of the water.

The temperature for the calcination should not exceed 1400 ° C. The lower temperature limit depends on the desired yield of nanocrystalline mixed oxide, the desired residual chlorine content and the content of germs. The formation of the nanoparticles begins at about 500 ⁰ C, but to keep the chlorine content low and the yield of nanoparticles high, but you will work preferably at 700 to 1100 ⁰ C, in particular at 1000 to 1100 ° C.

It has surprisingly been found that for the calcination 0.5 to 30 minutes, preferably 0.5 to 10, in particular 2 to 5 minutes are generally sufficient. Already after this short time can be among the above Conditions for the preferred temperatures a sufficient yield of nanoparticles can be achieved. However, one can also according to the information in Ber. DKG 74 (1997) no. 11/12, p. 722 for 4 hours at 700 ⁰ C or 8 hours at 500 ⁰ C calcine.

During calcination, agglomerates accumulate in the form of nearly spherical nanoparticles. These particles consist of Al ₂ O ₃ and optionally MeO. The content of MeO acts as an inhibitor of crystal growth and keeps the crystallite size small.

To obtain nanoparticles, the agglomerates are preferably comminuted by wet grinding in a solvent, for example in an attritor mill, bead mill or stirred mill. This gives nanoparticles which have a crystallite size of less than 1 .mu.m, preferably less than 0.2 .mu.m, more preferably between 0.001 and 0.9 microns. For example, after six hours of grinding, a suspension of nanoparticles with a d90 value of approximately 50 nm is obtained. Another possibility for deagglomeration is sonication.

For the inventive modification of the surface of these nanoparticles with coating agents which is a preferred variant of this invention, such as e.g. Silanes or siloxanes there are two possibilities. According to the first preferred variant, deagglomeration can be carried out in the presence of the coating agent, for example by adding the coating agent to the mill during milling. A second

It is possible to first destroy the agglomerates of the nanoparticles and then treat the nanoparticles, preferably in the form of a suspension in a solvent, with the coating agent.

Suitable solvents for the deagglomeration are both water and conventional solvents, preferably those which are also taken in the paint industry, such as C-ι-C ₄ alcohols, in particular methanol, ethanol or isopropanol, acetone, tetrahydrofuran ran , Butyl acetate. Is this done? Deagglomeration in water, an inorganic or organic acid, for example, HCl, HNO ₃ , formic acid or acetic acid should be added to stabilize the resulting nanoparticles in the aqueous suspension. The amount of acid may be 0.1 to 5 wt .-%, based on the total amount of nanoparticles. From this aqueous suspension of the acid-modified nanoparticles is then preferably the grain fraction having a particle diameter of less than 20 nm separated by centrifugation. Subsequently, at elevated temperature, for example at about 100 ^° C., the coating agent, preferably a silane or siloxane, is added. The nanoparticles thus treated precipitate, are separated and dried to a powder, for example by freeze-drying.

Suitable coating agents here are preferably silanes or siloxanes or mixtures thereof.

In addition, suitable coating agents are all substances which can bind physically to the surface of the mixed oxides (adsorption) or which can bond to form a chemical bond on the surface of the mixed oxide particles. Since the surface of the mixed oxide particles is hydrophilic and free hydroxy groups are available, suitable coating agents are alcohols, compounds having amino, hydroxyl, carbonyl, carboxyl or mercapto functions, silanes or siloxanes. Examples of such coating compositions are polyvinyl alcohol, mono-, di- and tricarboxylic acids, amino acids, amines, waxes, surfactants, hydroxycarboxylic acids, organosilanes and organosiloxanes.

Suitable silanes or siloxanes are compounds of the formulas

a) R [-Si (R'R ") - O-] _n Si (R ¹ R ¹ ^ -R ¹ " or cyclo - [-Si (R ¹ R ¹¹ KH Si (R'R ") - O)

wherein R, R ', R ", R ¹ " - identical or different from each other, an alkyl radical having 1-18 C atoms or a phenyl radical or an alkylphenyl or a phenylalkyl radical having 6 - 18 C-atoms or a radical of the general formula - ( Cmhbm-OJp-Cqhbq + i or a radical of the general formula -C ₃ H _2s Y or a radical of the general formula -XZ _t- i,

n is an integer meaning 1 <n <1000, preferably 1 <n <100, m is an integer 0 <m <12 and p is an integer 0 <p <60 and q is an integer 0 <q <40 and r is an integer 2 <r <10 and s is an integer 0 ≤ s <18 and

Y is a reactive group, for example α, β-ethylenically unsaturated groups, such as (meth) acryloyl, vinyl or allyl groups, amino, amido, ureido, hydroxyl, epoxy, isocyanato, mercapto, sulfonyl, phosphonyl,

Trialkoxylsilyl, alkyldialkoxysilyl, dialkylmonoalkoxysilyl, anhydride and / or carboxyl groups, imido, imino, sulfite, sulfate, sulfonate, phosphine, phosphite, phosphate, phosphonate groups and

X is a t-functional oligomer with t an integer 2 <t <8 and

Z in turn a rest

R [-Si (R ¹ R ¹¹ KHn Si (R ¹ R ¹¹ JR ¹ ") or cyclo - [-Si (R'R") - O-] _r Si (R'R ") - O-

represents as defined above.

The t-functional oligomer X is preferably selected from:

Oligoether, oligoester, oligoamide, oligourethane, oligourea, oligoolefin, oligovinyl halide, oligovinylidenedihalogenide, oligoimine, oligovinylalcohol, esters, acetal or ethers of oligovinyl alcohol, cooligomers of maleic anhydride, oligomers of (meth) acrylic acid, oligomers of (meth) acrylic esters, oligomers of (meth ) acrylamides, oligomers of (meth) acrylic acid imides, Oligomers of (meth) acrylonitrile, particularly preferably oligoethers, oligoesters, oligourethanes.

Examples of radicals of oligoethers are compounds of the type - (C _a H _2a O) _b - C _a H _2a - or O- (C _a H ₂ aO) _b -O -CaH _2a with 2 <a <12 and 1 <b <60, for example a diethylene glycol, triethylene glycol or tetraethylene glycol radical, a dipropylene glycol, tripropylene glycol, tetrapropylene glycol radical, a dibutylene glycol, tributylene glycol or tetrabutylene glycol radical. Examples of residues of Oligoestem are compounds of the type -C _b H _2b - (C (CO) C _a H _2a - (CO) OC _b H _2b -) _c - or -OC _b H _2b - (C (CO) C) _a H _2a - (CO) O- C _b H _2b -) _c -O- with a and b different or equal

3 <a <12, 3 <b <12 and 1 <c <30, e.g. B. an oligoester of hexanediol and adipic acid.

b) organosilanes of the type (RO) ₃ Si (CH ₂ ) _m -R 'R = alkyl, such as methyl, ethyl, propyl, m = 0.1-20 R ¹ = methyl, phenyl,

-C ₄ F ₉ ; OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂ -NH ₂ , -N ₃ , SCN ₁ -CH = CH ₂ , -NH-CH ₂ -CH ₂ -NH ₂ ,

-N- (CH ₂ -CH ₂ -NH ₂ ) ₂

-OOC (CH ₃ ) C = CH ₂

-OCH ₂ -CH (O) CH ₂

-NH-CO-N-CO- (CH ₂ ) ₅ -NH-COO-CH ₃ , -NH-COO-CH ₂ -CH ₃ , -NH- (CH ₂ J ₃ Si (OR) ₃

SH

-NR ¹ R ¹¹ R ¹ "(R ¹ = alkyl, phenyl, R" = alkyl, phenyl, R ¹ "= H, alkyl, phenyl,

Benzyl, C ₂ H ₄ NR "" with R "" = A, alkyl and R ¹ "" = H, alkyl).

Examples of silanes of the type defined above are, for. Hexamethyldisiloxane, octamethyltrisiloxane, other homologous and isomeric compounds of the series Si _n O _n-1 (CH ₃ ) ₂ n + 2, where n is an integer 2 <n <1000, e.g. B. Polydimethylsiloxane 200® fluid (20 cSt).

Hexamethyl-cyclo-trisiloxane, octamethyl-cyclo-tetrasiloxane, other homologous and isomeric compounds of the series

(Si-O) r (CH ₃ ) ₂ r, where r is an integer 3 ≤ r ≤ 12,

Dihydroxytetramethyldisiloxane, dihydroxyhexamethyltrisiloxane, dihydroxyoctamethyltetrasiloxane, other homologous and isomeric compounds of the series

HO - [(Si-O) _n (CH ₃ ) ₂ n] -Si (CH ₃ ) ₂ -OH or

HO - [(Si-O) _n (CH ₃ ) _2n ] - [Si-O) _m (C ₆ H ₅ ) _2m ] -Si (CH ₃ ) ₂ -OH, where m is an integer 2 <m <1000 is, preferably the α, co-dihydroxypolysiloxanes, z. B. polydimethylsiloxane

(OH end groups, 90-150 cSt) or polydimethylsiloxane-co-diphenylsiloxane,

(Dihydroxy end groups, 60 cST).

Dihydrohexamethyltrisiloxane, Dihydrooctamethyltetrasiloxan other homologous and isomeric compounds of the series H - [(Si-O) _n (CH ₃ ) _2n ] -Si (CH ₃ ) ₂ -H, where n is an integer 2 <n <1000, preferred are the α, ω-

Dihydropolysiloxanes, e.g. B. polydimethylsiloxane (hydride end groups, M _n = 580).

Di (hydroxypropyl) hexamethyltrisiloxane, dihydroxypropyl) octamethyltetrasiloxane, other homologous and isomeric compounds of the series HO- (CH ₂ ) _u [(Si-O) n (CH ₃ ) ₂ (CH ₂ ) u-OH, are preferably the α, ω -Dicarbinolpolysiloxanes with

3 <u <18, 3 <n <1000 or their polyether-modified successor compounds based on the ethylene oxide (EO) and propylene oxide (PO) as homo- or

Mixed polymer HO- (EO / PO) _v - (CH ₂ ) u [(Si-O) _t (CH ₃ ) _2t ] -Si (CH ₃ ) ₂ (CH ₂ ) u- (EO / PO) _v -OH, preferred are α, ω-di (carbinolpolyether) polysiloxanes with 3 <n <1000, 3 <u <18, 1 <v <50.

Instead of α, ω-OH groups, the corresponding difunctional compounds also come with epoxy, isocyanato, vinyl, allyl and di (meth) acryloyl groups used, for example, polydimethylsiloxane with vinyl end groups (850 - 1150 cST) or TEGORAD 2500 from. Tego Chemie Service.

There are also the esterification of ethoxylated / propoxylated trisiloxanes and higher siloxanes with acrylic acid copolymers and / or

Maleic acid copolymers as modifying compound, e.g. BYK Silclean 3700 from Byk Chemie or TEGO® Protect 5001 from Tego Chemie Service GmbH.

Instead of α, ω-OH groups, the corresponding difunctional compounds are also used with -NHR "" with R "" = H or alkyl, e.g. the well-known aminosilicone oils from Wacker, Dow Corning, Bayer, Rhodia, etc., which carry randomly distributed (cyclo) -alkylamino groups or (cyclo) -alkylimino groups on their polymer chain on the polysiloxane chain.

c) organosilanes of the type (RO) ₃ Si (C _n H _2n +!) and (RO) ₃ Si (C _n H _{2n +} I), where R is an alkyl, such as. For example, methyl, ethyl, n-propyl, i-propyl, butyl n 1 to 20.

Organosilanes of the type R'x (RO) ySi (CnH2n + 1) and (RO) 3Si (CnH2n + 1), wherein

R is an alkyl, such as. Methyl, ethyl, n-propyl, i-propyl, butyl,

R ^{1 is} an alkyl, such as. Methyl, ethyl, n-propyl, i-propyl, butyl,

R 'is a cycloalkyl n is an integer from 1 - 20 x + y 3 x 1 or 2 y 1 or 2

Organosilanes of the type (RO) ₃ Si (CH ₂ ) _m -R \ wherein R is an alkyl, such as. As methyl, ethyl, propyl, m is a number between 0.1 - 20

R ^{1 is} methyl, phenyl, -C ₄ F ₉ ; OCF ₂ -CHF-CF ₃ , -C ₆ F ₁₃ , -O-CF ₂ -CHF ₂ , -NH ₂ , -N ₃ , -SCN, -CH = CH ₂ , -NH-CH ₂ -CH ₂ -NH ₂ , -N- (CH ₂ -CH ₂ -NH ₂ J ₂ , -OOC (CH ₃ ) C = CH ₂ , -OCH ₂ -CH (O) CH ₂ , -NH-CO-N-CO- (CH ₂ ) ₅ , -NH-COO-CH ₃ ,

-NH-COO-CH ₂ -CH ₃ ,

-NH- (CH ₂ ) ₃ Si (OR) ₃ , -S _x - (CH ₂ ) ₃ ) Si (OR) ₃ , -SH-NR ¹ R ¹¹ R ¹ "(R ¹ = alkyl, phenyl;

R "= alkyl, phenyl; R ¹ " = H, alkyl, phenyl, benzyl, C ₂ H ₄ NR ¹¹¹¹ R with R "" = A, alkyl and

R " ¹ " = H, alkyl).

Preferred silanes are the silanes listed below: triethoxysilane, octadecyltimethoxysilane, 3- (trimethoxysilyl) -propylmethacrylate, 3- (trimethoxysilyl) -propylacrylate, 3- (trimethoxysilyl) -methylmethacrylate, 3- (trimethoxysilyl) -methylacrylate, 3- (trimethoxysilyl) ethylmethacrylate, 3- (trimethoxysilyl) -ethylacrylate, 3- (trimethoxysilyl) -pentylmethacrylate, 3- (trimethoxysilyl) -pentylacrylate, 3- (trimethoxysilyl) -hexylmethacrylate, 3- (trimethoxysilyl) -hexylacrylate, 3- (trimethoxysilyl) -butylmethacrylate , 3- (trimethoxysilyl) butyl acrylates, 3- (trimethoxysilyl) heptyl methacrylates, 3- (trimethoxysilyl) heptyl acrylates, 3- (trimethoxysilyl) octyl methacrylates, 3- (trimethoxysilyl) octyl acrylates, methyltrimethoxysilanes, methyltriethoxysilanes, propyltrimethoxysilanes, propyltriethoxysilanes, isobutyltrimethoxysilanes , Isobutyltriethoxysilanes, octyltrimethoxysilanes, octyltriethoxysilanes, hexadecyltrimethoxysilanes, phenyltrimethoxysilanes, phenyltriethoxysilanes, tridecafluoro-1,1,2,2-tetrahydr ooctyltriethoxysilane,

Tetramethoxysilanes, tetraethoxysilanes, oligomeric tetraethoxysilanes (DYNASIL® 40 from Degussa), tetra-n-propoxysilanes, 3-glycidyloxypropyltrimethoxysilanes, 3-glycidyloxypropyltriethoxysilanes,

3-methacryloxypropyltrimethoxysilanes, vinyltrimethoxysilanes, vinyltriethoxysilanes,

3-Mercaptopropyltrimethoxysilane,

3-aminopropyltriethoxysilanes, 3-aminopropyltrimethoxysilanes, 2-aminoethyl-3-aminopropyltrimethoxysilanes, triaminofunctional propyltrimethoxysilanes (DYNASYLAN® TRIAMINO from Degussa), N- (n-butyl-3-aminopropyltrimethoxysilanes, 3-aminopropylmethyldiethoxysilanes. The coating compositions, in particular the silanes or siloxanes, are preferably added in molar ratios of nanoparticles to silane of from 1: 1 to 10: 1. The amount of solvent in the deagglomeration is generally 80 to 90 wt .-%, based on the total amount of nanoparticles and solvent.

The deagglomeration by grinding and simultaneous modification with the coating agent is preferably carried out at temperatures of 20 to 150 ° C, more preferably at 20 to 90 ⁰ C.

If deagglomeration is carried out by grinding, the suspension is subsequently separated from the grinding beads.

After deagglomeration, the suspension can be heated to complete the reaction for up to 30 hours. Finally that will be

Distilled off solvent and the remaining residue dried. It may also be advantageous to leave the modified nanoparticles in the solvent and to use the dispersion for other applications.

It is also possible to suspend the nanoparticles in the corresponding solvents and to carry out the reaction with the coating agent after deagglomeration in a further step.

The nanoparticles according to the invention, preferably those which have been modified on the surface with silanes or siloxanes as described above, improve the tribological sliding properties of lubricants for winter sports equipment, in particular as an additive in ski waxes. Such ski waxes generally consist of paraffins, which have different viscosities depending on the type of snow and contain various additives. example

Production of nanoparticles

50 g of corundum powder with a grain size in the range 10 to 50 μm, consisting of crystallites <100 nm, were suspended in 180 g of isopropanol. 5 g of trimethoxy-octadecylsilane were added to the suspension and fed to a vertical stirred ball mill from Netzsch (type PE 075). The grinding beads used consisted of zirconium oxide (stabilized with yttrium) and had a size of 0.3-0.5 mm. After three hours, the suspension was separated from the milling beads and boiled under reflux for a further 4 h. Subsequently, the solvent was distilled off and the residual moist residue in a drying oven at 110 ⁰ C dried for a further 20 h.

Two pairs of identical skis made by Dynastar Belag P-tex 3000 were impregnated with Star SkiWax Eclipse EC1 high fluorine +8 ...- 3 ⁰ C, stripped off with a wax blade and treated with a textured brush. The air temperature was +1, 5 ⁰ C. The driver was the same in every attempt.

On a pair of skis, corundum powder or hydrophobized corundum powder was additionally rubbed with a cork and the sanding structure was again worked out with a textured brush. As corundum powder or hydrophobic corundum, the products described above were used.

The nano corundum skis glided faster and reached a higher level

Final speed than the reference ski. This was again checked by a slide in an opposite slope, with the ski with the modification about 10% more distance in the opposite direction covered than the reference ski at the same approach.

Thereafter, the above-described wax was heated and mixed with 10% by weight of surface-modified nanocorner. One ski was treated with the conventional wax described above, the other with the modified wax, which was done in the same way as described above. Here was also the modified ski at an advantage, but he put in the above-described Gegenhangversuch now only about 20% more distance in the opposite back.

All the experiments just described were carried out in the same way now in cold snow (air temperature -8 ° C). The wax used was Star SkiWax Eclipse EC2 high fluorine 0 ...- 10 ⁰ C.

Here, the results were as follows: The sample with ragged surface-modified nanocorundum returned about 20% more distance in the opposite slope compared to the reference sample.

The sample with the surface-modified nanocorner mixed into the wax at 10% by weight put back about 10% more distance in the opposite slope than the reference sample.

Furthermore, the modified waxes held much longer on the sliding surfaces, which suggests an improvement in Abriebeigenschaften.

Claims

claims

1. Lubricant for winter sports equipment containing nanocorundum.

2. A lubricant according to claim 1 containing Nanokorund, from 50 to

99.9 wt .-% Al ₂ O ₃ and 0.1 to 50 wt .-% of an oxide of the I or II. Main group of the Periodic Table.

3. A lubricant according to claim 1 containing nanocorundum whose surface is modified with silanes or siloxanes.

4. A lubricant according to claim 1 containing nanocorundum with a crystallite size smaller than 1 micron.