Polysiloxane dispersing agent

Abstract

The invention relates to the use of a polysiloxane having a plurality of siloxane groups and at least one cyclic carboxylic anhydride group or the hydrolysis product thereof covalently linked to the polysiloxane, as a dispersing agent for solid particles in a non-aqueous composition.

Description

The invention relates to the use of a polysiloxane having a plurality of siloxanegroups as a dispersing agent for solid particles in a non-aqueous composition, andto a non-aqueous composition comprising a polysiloxane having a plurality ofsiloxane groups, a dispersion medium, and solid particles. The invention furtherrelates to a process for dispersing solid particles in a non-aqueous composition.A large number and variety of substances can be used as dispersants for pigmentsand fillers. Alongside simple compounds with a low molecular mass, such as fattyacids and their salts or various silanes such as alkyl or vinyl silanes, for example,complex structures are also used.EP 0931537 B1 describes the dispersion of organic and inorganic powders in oilcontaining compositions by means of polysiloxane-containing compounds. Thepolymers are prepared by radical copolymerization of vinylic polysiloxanemacromonomers with other vinylic monomers, the other vinylic monomerscontaining a nitrogen-containing group, a polyoxyalkylene group, an anionic group,or a polylactone group.US 9217083 B2 describes a copolymer which contains at least one polysiloxanegroup and the skeletal structure of which is an addition compound of at least oneamine and at least one epoxide. The invention further relates to the use of saidproducts as dispersing agent for organic and inorganic pigments and fillers in oil-based compositions, and especially in silicone containing compositions.US 7329706 B2 describes a heat-conductive silicone composition comprising anorganopolysiloxanes, a heat-conductive filler, and a specific polysiloxanemacromonomer bearing alkoxysilane groups as dispersant.EP 2107078 A1 describes the reaction of a of an Si-H functional polysiloxane withally succinic anhydride to prepare an anhydride functional polysiloxane. Theanhydride functional polysiloxane is subsequently hydrolyzed to form a dicarboxylicacid functional polysiloxane. Titanium dioxide powder and zinc oxide are treatedwith this material.JP 2020 / 059771 A describes a dispersant having a silicone structure and adicarboxylic acid anhydride structure at one end of the silicone structure. Thedispersant is used to treat zirconia, which is subsequently dispersed in silicone oil.While the prior-art dispersants provide an acceptable stability of dispersed pigmentsand / or fillers, there remains a demand for improved systems, for lowering thesedimentation of pigments, enhancing the color faithfulness of pigment dispersions,reducing the viscosity and ensuring a broader compatibility of dispersants withregard to different compositions - such as, for example, compatibility with veryapolar compositions, such as oil-based and silicone-based compositions.Silicone containing compositions can be non-curable or curable compositions, suchas condensation or addition curing. In the case of addition curing, the compositionconsists of 2 parts, SiH- and vinyl-functional organopolysiloxane components, andtypically a Platinum based catalyst is used. If the composition further containsfunctional filler(s) or pigment(s), a dispersing agent is generally used tocompatibilise the filler(s) or pigment(s) and the silicone. Known dispersing agentshave been found insufficient to fully disperse the filler(s) or pigment(s). In particular,it was not possible to achieve a sufficiently low viscosity of the composition and atthe same time not having a negative influence on the curing process.In the field of modern electronic devices heat management plays a constant growingrole. Without thermal conductive materials the advances in microelectronicstechnology wouldn’t have resulted in electronic devices that process signals anddata at unprecedented high speeds. Electronic and / or integrated circuit (“IC”)devices, e.g., microprocessors, memory devices, printed circuit, etc, becomesmaller while heat dissipation requirements get larger.To realize high thermal conductivity in potting materials, gaskets, solder pasts,underfills, thermal interface materials as (e.g. thermal gap fillers, gap pads, sil pads,phase change materials, thermal conductive grease, thermal gel, Thermal Cladmaterials, thermal encapsulants), adhesives, sealants and coatings, high thermalconductive particles loadings are needed. The significant drawback of those highlyfilled systems is that high filler loadings increase the conductive material viscosityto undesirably high levels and impair the application properties substantially.The present invention seeks to solve or alleviate the above-mentioned drawbacksby combining an efficient dispersing effect and curing speed.The invention relates to the use of a polysiloxane having a plurality of siloxanegroups and at least one cyclic carboxylic anhydride group or the hydrolysis productthereof covalently linked to the polysiloxane, as a dispersing agent for solid fillerparticles in a non-aqueous composition comprising a dispersion medium, whereinthe content of the filler particles is in the range of from 500 to 2500 parts by weightper 100 parts by weight of the dispersion medium.The above-mentioned use may also be described as a process of dispersing apigment / filler in a non-aqueous composition comprising the step of adding apolysiloxane having a plurality of siloxane groups and at least one cyclic carboxylicanhydride group or the hydrolysis product thereof covalently linked to thepolysiloxane to a non-aqueous composition comprising solid particles, followed bydispersing the solid particles in the non-aqueous composition. The liquidcomposition may be used as such or further be reacted with a crosslinker to obtaina cured composition. In such a case, there are no limitations concerning the curemechanism of the liquid composition, which can be based, for instance, on ahydrosilylation reaction, condensation reaction, addition reaction or an organicperoxide-induced free radical reaction.A non-aqueous composition is a composition wherein the content of water is below10 % by weight, preferably below 5 % by weight, calculated on the weight of thecomposition. In some embodiments, the non-aqueous composition is free oressentially free of water.It has been found that the use of a polysiloxane having a plurality of siloxane groupsand at least one cyclic carboxylic anhydride group or the hydrolysis product thereofcovalently linked to the polysiloxane, as a dispersant in a composition comprisingsolid particles provides improved dispersing properties. When used in pottingmaterials, gaskets, solder pastes, underfills, thermal interface materials such asthermal gap fillers, gap pads, sil pads, phase change materials, thermal conductivegrease, thermal gel, thermal clad materials, thermal encapsulants, adhesives,sealants and coatings compositions, it is possible to reduce the viscosity.The use of the non-aqueous composition as a thermal interface material is preferred,in particular as a thermal interface material in an electronic component.As mentioned above, the polysiloxane has at least one cyclic carboxylic anhydridegroup or the hydrolysis product thereof covalently linked to the polysiloxane. Thehydrolysis product of a cyclic carboxylic anhydride is the corresponding dicarboxylicacid or a salt thereof. Suitable examples of cyclic carboxylic anhydride groups arethose derived from bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride, 5- norbornene-2,3-carboxylic anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride,maleic anhydride, tetrahydrophthalic anhydride, citraconic anhydride, itaconicanhydride, allyl succinic anhydride. In some embodiments, the cyclic carboxylicanhydride group is present in the form of a 5-membered ring. In a furtherembodiment, the at least one cyclic carboxylic anhydride group is derived from allylsuccinic anhydride. In another embodiment, the cyclic carboxylic anhydride groupis present as a 6-membered ring. If the polysiloxane has two or more cycliccarboxylic anhydride groups covalently linked to it, the individual anhydride groupsmay be of the same or of different types. In some embodiments, the polysiloxanehas more than two cyclic carboxylic anhydride groups or the hydrolysis productthereof covalently linked to it. In other further embodiment, the polysiloxane has twocyclic carboxylic anhydride groups linked to it. In a still further embodiment, thepolysiloxane has one cyclic carboxylic anhydride group or the hydrolysis productthereof linked to it. However, it is also possible to use a mixture of polysiloxanes,for example of a first polysiloxane having one or more cyclic carboxylic anhydridegroups or the hydrolysis product thereof linked to it, and a second differentpolysiloxane having one or more cyclic carboxylic anhydride groups or thehydrolysis product thereof linked to it.The cyclic carboxylic anhydride groups or the hydrolysis products thereof may bepositioned along the polysiloxane chain at various positions. In some embodiments,the at least one anhydride group is covalently linked to the polysiloxane as aterminal group at the two ends of a polysiloxane chain. A polymer morphologywherein two anhydride groups are located at the two ends of polysiloxane chainmay also be referred to as ABA polymer. In further embodiments, the at least oneanhydride group is covalently linked to the polysiloxane as a terminal group at theone end only of a polysiloxane chain. A polymer morphology wherein only anhydridegroups is located at one end only of a polysiloxane chain may also be referred toas macromonomer. Alternatively, or additionally, the at least one anhydride groupis covalently linked to the polysiloxane at a non-terminal position. A polymermorphology wherein several anhydride groups are pending from a polysiloxanechain at different positions may also be referred to as a comb polymer.The polysiloxane having a plurality of siloxane groups generally has 1 to 15 cycliccarboxylic anhydride groups or the hydrolysis products thereof covalently linked toit. In a preferred embodiment, 1 to 10, and more preferred 1 to 2 cyclic carboxylicanhydride groups or the hydrolysis products thereof are covalently linked to thepolysiloxane. In some embodiments, a mixture of polysiloxanes having differentnumbers of cyclic carboxylic anhydride groups or the hydrolysis products thereofcan be employed. If such mixtures are employed, the number of cyclic carboxylicanhydride groups or the hydrolysis products thereof relates to the average numberof cyclic carboxylic anhydride groups or the hydrolysis products thereof. In apreferred embodiment on average 0.7 to 3.0 cyclic carboxylic anhydride groups orthe hydrolysis product thereof are covalently linked to a polysiloxane molecule.The polysiloxane having a plurality of siloxane groups and at least one cycliccarboxylic anhydride group or the hydrolysis product thereof covalently linked to thepolysiloxane can be prepared according to known methods. In preferredembodiments, the cyclic carboxylic anhydride group or the hydrolysis productthereof is linked to the polysiloxane via a Si-C bond.In one embodiment, the compounds in question are prepared by a hydrosilylationreaction, wherein a polysiloxane having a plurality of siloxane groups and at leastone Si-H group is reacted with an anhydride compound having an ethylenicallyunsaturated group. Such reactions are generally catalyzed by metal-basedcatalysts. Details of such hydrosilylation reactions and suitable conditions are generally known.Hydrosilylation catalysts employed are preferably noble metals and theircompounds, such as platinum, rhodium, and palladium and their compounds, morepreferably platinum compounds. Especially preferred platinum compounds arehexachloroplatinic acid, alcoholic solutions of hexachloroplatinic acid, complexeswith platinum and aliphatic, unsaturated hydrocarbon compounds; and platinumvinylsiloxane complexes. It is also possible, however, to use platinum black andplatinum on activated carbon. If, for example, a platinum compound is used, 1 to50 ppm as platinum metal are preferably used.The progress of the hydrosilylation reaction may be monitored by gas-volumetricdetermination of the remaining SiH groups or by infrared spectroscopy (absorptionband of the silicon hydride at 2150 cm-1). The polysiloxanes of the inventionpreferably contain no residual Si-H groups. When the polysiloxane having a plurality of siloxane groups and at least one cycliccarboxylic anhydride groups or the hydrolysis products thereof covalently linked tothe polysiloxane is prepared by a hydrosilylation reaction of an ethylenicallyunsaturated anhydride, a covalent link between the polysiloxane and the at leastone anhydride group is formed. One specific example of ethylenically unsaturatedanhydride which is suitable for the preparation of polysiloxanes used according tothe invention is allyl succinic anhydride.The synthetic route described above requires a polysiloxane having a plurality ofsiloxane groups and at least one Si-H group as starting material. Suitable polysiloxane having at least one Si-H group can be represented by the followinggeneral formula (I)MaM′bDcD′dTeQf (I)wherein• M represents [R3SiO1 / 2]• M′ represents [R2SiHO1 / 2]• D represents [R2SiO2 / 2]• D′ represents [RSiHO2 / 2]• T represents [RSiO3 / 2]• Q representsSiO4 / 2]• a is an integer of 0 to 10, preferably 0 to 1, more preferably 1,• b is an integer of 0 to 10, preferably 1 to 2, more preferably 1,• c is an integer of 0 to 500, preferably 2 to 300, more particularly 5 to 250,• d is an integer of 0 to 100, preferably 0 to 50, more particularly 0 to 30,• e is an integer of 0 to 10, preferably 0 to 5, more particularly 0,• f is an integer of 0 to 10, preferably 0 to 5, more particularly 0,with the proviso that a+b≧2 and b+d≧1• R independent of each other represents a C1 to C30 hydrocarbon radical,preferably methyl, octyl or phenyl, (α-methyl)styryl, more preferably methyl.The description of polysiloxanes using M, D, T and Q units is generally known inthe art.Generally, the polysiloxane having SiH groups are synthesized using the classicequilibration reaction known in the prior art.Generally, the polysiloxane has 1 to 15 SiH groups, preferably 1 to 10, and morepreferably 1 to 2 SiH groups. Generally, the polysiloxane has 4 to 70 Silicon atoms,preferably 10 to 50 silicon atoms.If so desired, the polysiloxane having a plurality of siloxane groups and twoanhydride group covalently linked to the polysiloxane can be prepared by othersuitable synthetic routes, for example by equilibration reactions of anhydridefunctional polysiloxane of ABA structure, such as described in EP 0 112 845 B1, inparticular Example 4 of this document.The number average molecular weight of the polysiloxane having a plurality ofsiloxane groups and at least one anhydride group covalently linked to thepolysiloxane generally is within the range of 300 to 15000 g / mol, preferably 500 to10000 g / mol, and even more preferably 800 to 8000 g / mol.The number average molecular weight can be determined by gel permeationchromatography carried out at 22°C using a separation module Waters 2695 and arefractive index detector Waters 2414. Toluene is a suitable eluent, using polydimethylsiloxane standards for calibration.Optionally, the polysiloxane having a plurality of siloxane groups and at least oneanhydride group covalently linked to the polysiloxane can have additional structuralsegments. Such optional segments may be included to adjust and fine-tune thecompatibility with the systems wherein they are employed, and other properties ofthe polysiloxane. Examples of such optional segments are polyether segments, forexample based on polyethylene oxide and / or polypropylene oxide, polyestersegments, hydrocarbon segments, fluorinated hydrocarbon segments, andpolyurethane segments. These optional segments may be connected to thepolysiloxane backbone by hydrosilylation or dehydrogenative condensation. Suchdehydrogenative condensation reactions are suitably catalyzed by metal complexes.This reaction type is described in German patent application DE 102005051939 A.These optional segments are preferentially connected to the polysiloxane backboneby hydrosilylation.In many embodiments the polysiloxane having a plurality of siloxane groups and atleast one anhydride group covalently linked to the polysiloxane is a liquid at roomtemperature. It can be used according to the invention and included in liquidcompositions as such as 100 % active substance. If so desired, the polysiloxanecan also be diluted with an organic solvent or an oil or a silicone prior to including itin a liquid composition. In a still further embodiment, the polysiloxane can beincluded in the liquid composition as emulsion or dispersion. The liquid compositionpreferably contains the polysiloxane in an amount to achieve effective dispersingproperties. The specific amount depends on the content of solid particles, such aspigments and / or fillers in the composition and the degree of dispersion which isrequired. Generally, the liquid composition contains the polysiloxane in an amountof from 0.001 to 10.000 wt.-%, preferably of from 0.010 to 8.000 wt.-%, morepreferably of from 0.050 to 7.000 wt.-% or of from 0.060 to 6.000 wt.-% or of from0.080 to 5.000 wt.-%, in particular of from 0.100 to 2.000 wt.-%, based in each caseon the total weight of the composition.The dispersions of pigment and / or filler in accordance with the present inventioncan be used in a wide range of formulations, including resins, oils, greases,lubricants, rubber materials, potting materials, gaskets, solder pasts, underfills,thermal interface materials as (e.g. thermal gap fillers, gap pads, sil pads, phasechange materials, thermal conductive grease, thermal gel, Thermal Clad materials,thermal encapsulants), adhesives, sealants, coatings, waxes, or materialcompositions. The dispersions may also be used in formulations which areproduced in the body care industry, or in electrical applications in the electronicsindustry, in the marine industry, for medical applications, in the construction industry,or in the electronic, battery and automotive industry. Examples include cosmeticproducts, electronic paper, such as, for example, the display in E-books, theencapsulation of microelectronic chips, submarine skin coatings, such as, forexample, antifouling coatings, silicone tubes, or lubricity additives for brakecomponents.The dispersions are particularly suitable for use in Thermally Interface Materials(TIM) products. These materials are used as interfaces between devices or partsthereof to dissipate heat from these devices (e.g., microprocessors). One typicalTIM typically includes a polymer matrix and one or more thermally conductivefiller(s). The TIM technologies used for electronic devices encompass severalclasses of materials such as epoxies, greases, sheets, pads, phase changematerials, filled polymer matrices such as elastomers, gels, carbon-based materials,adhesives. U.S. Pat. No. 6,469,379 describes a silicone based TIM including a vinylterminated Silicon polymer; a silicone cross-linker having terminal Silicon-hydride units, a chain extender, and a thermally conductive filler, such as a metal (e.g.,Aluminum, Silver, etc.) and / or a ceramic (e.g., aluminum nitride, aluminum oxide,zinc oxide, etc.).The use of the non-aqueous composition as a thermal interface material is preferred,in particular as a thermal interface material in an electronic component.One aspect of the present invention relates to a process for producing a dispersion,said process comprising the mixing of at least one pigment and / or filler in a vehicleselected from the group consisting of at least one silicone oil and or silicone rubbermaterial, with the aid of at least one anhydride modified polysiloxane of the invention.These dispersions represent preferably pigment preparations and / or fillerpreparations, which are used preferably for various compositions.In a further embodiment, the dry filler is treated with a polysiloxane having a pluralityof siloxane groups and at least one cyclic carboxylic anhydride group or thehydrolysis product thereof covalently linked to the polysiloxane to modify the surfaceof the dry filler, followed by mixing the treated filler with a dispersion medium.In a preferred embodiment, the non-aqueous composition comprises a dispersionmedium which is different from the polysiloxane having a plurality of siloxane groupsand at least one cyclic carboxylic anhydride group or the hydrolysis product thereof.In a further preferred embodiment, the dispersion medium comprises a silicone.In some embodiments, the silicone is a silicone oil or silicone rubber.Examples of silicone oils include those of the following structures:(II)(III)R3 4-zSi(OSi(CH3)3)z (IV)where R2 is selected from the group consisting of hydrogen, a hydroxyl group, alkylor fluorinated alkyl groups having 2 to 20 carbon atoms, aryl groups, aminoalkylgroups, C6-22 alkoxy groups, and a group of the formula (CH3)3SiO[(CH3)2SiO]ySi(CH3)2CH2CH2—, in which y is an integer from 0 to 500. R3 is a C1-20alkyl group. In formula (II), h is an integer from 0 to 1000, i is an integer from 0 to1000, with the proviso that h+i is 1 to 2000, and each j and k independently of one another is 0, 1, 2, or 3. In formula (III) l and m are integers from 0 to 8, with l+mranging from 3 to 8, and in formula (IV), z is an integer from 1 to 4. Examples of theradical R2 include methyl, ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, tetradecyl,hexadecyl, octadecyl, trifluoropropyl, nonafluorohexyl, heptadecylfluorodecyl,phenyl, aminopropyl, dimethylaminopropyl, aminoethylaminopropyl, stearoxy,butoxy, ethoxy, propoxy, cetyloxy, myristyloxy, styryl, and alpha-methylstylyl,among which preference is given to hexyl, octyl, decyl, dodecyl, tetradecyl,hexadecyl, octadecyl, trifluoropropyl, phenyl, aminopropyl, andaminoethylaminopropyl. Examples of the silicone oil include organopolysiloxaneswith low or high viscosity, such as dimethylpolysiloxane, methylphenylpolysiloxane,methyl-hydrogenpolysiloxane, and dimethyl siloxane-methyl-phenylsiloxanecopolymer, for example; cyclosiloxanes, such as octamethylcyclotetrasiloxane (D4),decamethyl-cyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6),tetramethyltetrahydrogencyclotetrasiloxane (H4), andtetramethyltetraphenylcyclotetrasiloxane; tris-trimethylsiloxysilane (M3T),tetrakistrimethylsiloxysilane (M4Q); branched siloxanes, such astristrimethylsiloxypropylsilane, tristrimethylsiloxy-butylsilane,tristrimethylsiloxyhexylsilane, and tristrimethylsiloxyphenylsilane, for example;higher alcohol-modified silicones, such as steroxysilicone; alkyl-modified silicones,amino-modified silicones, and fluoro-modified silicones.In some embodiments, the silicone dispersion medium is a crosslinkable silicone.The crosslinkable silicones may be present in a multiplicity of forms and compounds,such as, for example, as silicone oils, silicone with high solids, water-basedsilicones, silicon alkyds, siliconized polyesters, or siliconized acrylic resins.Crosslinking may take place by moisture curing, hydrosilylation curing, radiationcuring, free-radical induced curing, or a combination of radiation and thermal curing(dual cure). Crosslinkable silicones are also referred to as silicone rubbers or liquid silicone rubbers.Methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl,dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl,nonadecyl, eicosyl, and other linear alkyl groups; isopropyl, tertiary butyl, isobutyl,2-methyl undecyl, 1-hexylheptyl, and other branched alkyl groups; cyclopentyl,cyclohexyl, cyclododecyl, and other cyclic alkyl groups; vinyl, allyl, butenyl, pentenyl,hexenyl, and other alkenyl groups; phenyl, tolyl, xylyl, and other aryl groups; benzyl,phenethyl, 2- (2,4,6-trimethylphenyl)propyl, and other aralkyl groups; 3,3,3-trifluoropropyl, 3-chloropropyl, and other halogenated alkyl groups are suggestedas the silicon-bonded groups of the organopolysiloxane. Preferably, such groupsare alkyl, alkenyl, or aryl groups, and especially preferably, methyl, vinyl, or phenyl.In addition, there are no limitations on the viscosity of the organopolysiloxane at 25°C. However, the viscosity is preferably within the range of from 20 to 100,000 mPa·s,more preferably, within the range of from 50 to 100,000 mPa·s, still more preferably,within the range of from 50 to 50,000 mPa·s, and especially preferably, within therange of from 100 to 50,000 mPa·s. This is due to the fact that when its viscosity at25° C. is less than the lower limit of the above-mentioned range, the physicalproperties of the resultant silicone compositions tend to decrease, and, on the otherhand, when it exceeds the upper limit of the above-mentioned range, thehandleability of the resultant silicone compositions tends to decrease. There are nolimitations concerning the molecular structure of such an organopolysiloxane, whichmay be, for instance, linear, branched, partially branched linear, or dendritic(dendrimeric), and is preferably linear or partially branched linear. Examples of suchorganopolysiloxanes include, for instance, homopolymers possessing the above mentioned molecular structures, copolymers having the above-mentionedmolecular structures, or mixtures of the above-mentioned polymers.Dimethylpolysiloxane having both terminal ends of its molecular chain blocked bydimethylvinylsiloxy groups, dimethylpolysiloxane having both terminal ends of itsmolecular chain blocked by methylphenylvinylsiloxy groups, dimethylsiloxane15 methylphenyl siloxane copolymer having both terminal ends of its molecular chainblocked by dimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxanecopolymer having both terminal ends of its molecular chain blocked bydimethylvinylsiloxy groups, dimethylsiloxane-methylvinylsiloxane copolymer havingboth terminal ends of its molecular chain blocked by trimethylsiloxy groups,methyl(3,3,3-trifluoropropyl)-polysiloxane having both terminal ends of its molecularchain blocked by dimethyl-vinylsiloxy groups, dimethylsiloxane-methylvinylsiloxanecopolymer having both terminal ends of its molecular chain blocked by silanolgroups, dimethylsiloxane-methylvinyl-siloxane-methylphenylsiloxane copolymerhaving both terminal ends of its molecular chain blocked by silanol groups,organosiloxane copolymer consisting of siloxane units represented by the formula(CH3)3SiO1 / 2, siloxane units represented by the formula (CH3)2(CH2=CH)SiO1 / 2,siloxane units represented by the formula CH3SiO3 / 2, and siloxane units representedby the formula (CH3)2SiO2 / 2, dimethylpolysiloxane having both terminal ends of itsmolecular chain blocked by silanol groups, dimethylsiloxane-methylphenyl siloxanecopolymer having both terminal ends of its molecular chain blocked by silanolgroups, dimethylpolysiloxane having both terminal ends of its molecular chainblocked by trimethoxysiloxy groups, dimethylsiloxane-methylphenylsiloxanecopolymer having both terminal ends of its molecular chain blocked bytrimethoxysilyl groups, dimethylpolysiloxane having both terminal ends of itsmolecular chain blocked by methyldimethoxysiloxy groups, dimethylpolysiloxanehaving both terminal ends of its molecular chain blocked by triethoxysiloxy groups,dimethylpolysiloxane having both terminal ends of its molecular chain blocked bytrimethoxysilylethyl) groups, and mixtures of two or more of the above-mentionedcompounds are suggested as examples of such organopolysiloxanes.When the composition is cured by means of a hydrosilation reaction, the dispersionmedium is preferably an organopolysiloxane having an average of not less than 0.1silicon-bonded alkenyl groups per molecule. More preferably, it is anorganopolysiloxane having an average of not less than 0.5 silicon-bonded alkenylgroups per molecule, and especially preferably, it is an organopolysiloxane havingan average of not less than 0.8 silicon-bonded alkenyl groups per molecule. This isdue to the fact that when the average number of silicon-bonded alkenyl groups permolecule is less than the lower limit of the above-mentioned range, the resultantcompositions tend to fail to cure to a sufficient extent. The silicon-bonded alkenylgroups of the organopolysiloxane are exemplified by the same alkenyl groups asthose mentioned above and are preferably represented by vinyl. In addition, siliconbonded groups other than the alkenyl groups in the organopolysiloxane areexemplified by the same linear alkyl, branched alkyl, cyclic alkyl, aryl, aralkyl,halogenated alkyl groups as those mentioned above. They are preferablyrepresented by alkyl and aryl groups, and especially preferably, by methyl andphenyl. There are no limitations concerning the molecular structure of suchorganopolysiloxanes, which is exemplified by the same structures as thosementioned above, and is preferably linear or linear with partial branching. Suchorganopolysiloxanes are exemplified, for instance, by homopolymers having theabove-mentioned molecular structures, copolymers having the above-mentioned molecular structures, or mixtures of these polymers. Such organopolysiloxanes areexemplified by organopolysiloxanes having the same alkenyl groups as thosementioned above.When the composition is cured by means of a condensation reaction, the dispersionmedium is an organopolysiloxane having at least two silanol groups or silicon30 bonded hydrolyzable groups per molecule. Examples of the silicon-bondedhydrolyzable groups in the organopolysiloxane include, for instance, methoxy,ethoxy, propoxy, and other alkoxy groups; vinyloxy, propenoxy, isopropenoxy, 1-ethyl-2-methylvinyloxy, and other alkenoxy groups; methoxyethoxy, ethoxyethoxy,methoxypropoxy, and other alkoxyalkoxy groups; acetoxy, octanoyloxy, and otheracyloxy groups; dimethylketoxime, methylethylketoxime, and other ketoximegroups; dimethylamino, diethylamino, butylamino, and other amino groups;dimethylaminoxy, diethylaminoxy, and other aminoxy groups; N-methylacetamidogroups, N-ethylacetamido, and other amido groups. In addition, the silanol groupsand silicon-bonded hydrolyzable groups of the organopolysiloxane are exemplifiedby the same linear alkyl, branched alkyl, cyclic alkyl, alkenyl, aryl, aralkyl, andhalogenated alkyl groups as those mentioned above. There are no limitationsconcerning the molecular structure of such organopolysiloxanes, which isexemplified by the same structures as those mentioned above and is preferablylinear or partially branched linear. Such organopolysiloxanes are exemplified byorganopolysiloxanes having at least two silanol groups or silicon-bondedhydrolyzable groups per molecule, said groups being the same as those mentionedabove.When the composition is cured by means of an organic peroxide-induced freeradical reaction, there are no limitations concerning the organopolysiloxane of thedispersion medium. However, it is preferably an organopolysiloxane having at leastone silicon-bonded alkenyl group. Silicon-bonded groups in such anorganopolysiloxane are exemplified by the same linear alkyl, branched alkyl, cyclicalkyl, alkenyl, aryl, aralkyl, and halogenated alkyl groups as those mentioned aboveand are preferably alkyl, alkenyl, or aryl groups, with methyl, vinyl, and phenyl beingparticularly preferable. There are no limitations concerning the molecular structureof such an organopolysiloxane, which is exemplified by the same structures asthose mentioned above and is preferably linear or partially branched linear. Suchorganopolysiloxanes are exemplified, for instance, by homopolymers having theabove-mentioned molecular structures, copolymers having the above-mentionedmolecular structures, or mixtures of the above-mentioned polymers. Suchorganopolysiloxanes are exemplified by the same organopolysiloxanes as thosementioned above.Silicone rubbers may be categorized as room temperature vulcanizing (RTV)silicone rubbers or as high temperature vulcanizing (HTV) silicone rubbers. Theyare generally known and described, for example, in US 6172150 B1, WO2018051158 A1, WO 2003078527 A1, US 6194508 B1, and WO 2003057782 A1.Liquid silicone rubbers are further described in WO 2015003978 A1, WO2018051158 A1, and WO 2020223864 A1.Suitable crosslinkable silicones are commercially available, for example under thetrade designation ELSATOSIL® and SEMICOSIL® from Wacker Chemie AG.As mentioned above, the polysiloxane having a plurality of siloxane groups and atleast one cyclic carboxylic anhydride group or the hydrolysis product thereofcovalently linked to the polysiloxane is used as a dispersing agent for solid particlesin a non-aqueous composition. Examples of solid particles include pigments andfillers.The solid particles may be surface-modified, wherein the surfaces may have, forexample, hydrophilic, amphiphilic or hydrophobic compounds or groups. Thesurface treatment may consist in providing the pigments with a thin hydrophilic and / or hydrophobic inorganic or organic layer by methods known to the person skilledin the art.In preferred embodiments, the average particle size of solid particles is in the rangeof 0.1 to 500.0 μm, preferably 0.1 to 100 µm.The average particle size relates to the D50 mass average particle size determinedby laser diffraction analysis according to ISO 13320:2009-10.In further preferred embodiments, the solid particles comprise aluminum oxideparticles. It is particularly preferred that the aluminum oxide particles comprise atleast one of spherical aluminum oxide particles having an average particle size inthe range of 1.0 to 50.0 μm and irregular-shaped aluminum oxide particles havingan average particle size in the range of 0.1 to 50.0 μm.Pigments include inorganic and organic pigments, pigment blacks, effect pigmentssuch as, for example, pearlescent and / or metal effect pigments, glitter pigmentsand mixtures thereof.Suitable organic pigments include for example nitroso, nitro, azo, xanthene,quinoline, anthraquinone, phthalocyanine, metal complex, isoindolinone,isoindoline, quinacridone, perinone, perylene, diketopyrrolopyrrole, thioindigo,Dioxazine, triphenylmethane and quinophthalone compounds. Furthermore, theorganic pigments can be selected, for example, from: carmine, carbon black, anilineblack, azo yellowb, quinacridone, phthalocyanine blue. Examples of these are: D &C Red (CI 45), D & C Orange (CI 45), D & C Red 3 (CI 45530), D & C Red 7 (CI 15850), D & C Red 4 (CI 15 510), D & C Red 33 (CI 17 200), D & C Red 34 (CI 15880), D & C Yellow 5 (CI 19 140), D & C Yellow 6 (CI 15 985), D & C Green (CI 61570), D & C Yellow 10 (CI 77 002), D & C Green 3 (CI 42 053) and / or D & C Blue1 (CI 42 090).Suitable inorganic pigments comprise, for example, metal oxides or other metalcompounds which are sparingly soluble or at least substantially insoluble in water,in particular oxides of titanium, for example titanium dioxide (CI 77891), zinc, iron,for example red and black iron oxide (CI 77491 (red), 77499 (black) ), Or iron oxidehydrate (CI 77492, yellow), zirconium, silicon, manganese, aluminum, cerium,chromium and mixed oxides of the elements mentioned and mixtures thereof.Further suitable pigments are barium sulfate, zinc sulfide, manganese violet,Ultramarin blue and Berlin blue pigments.With regard to pearlescent pigments, for example, the following types or types ofpearlescent pigments can be used:• Natural pearlescent pigments such as, for example, "fish silver" (guanine / hypoxanthine mixed crystals from fish scales) and "mother-of-pearl" (groundmussel shells)• Monocrystalline pearlescent pigments such as, for example, bismuthoxychloride (BiOCl) or platelet-shaped titanium dioxide, and• Layer substrate pearlescent pigments.Suitable platelet-shaped transparent substrates to be coated for the layer-substratepearlescent pigments are non-metallic, natural or synthetic platelet-shaped• substrates. The substrates are preferably essentially transparent, preferablytransparent, i.e. at least partially transparent to visible light.The platelet-shaped transparent substrates can be selected from the groupconsisting of natural mica, synthetic mica, glass flakes, SiO2 platelets, Al2O3, Kaolin,graphite, talc, polymer platelets, platelet-shaped bismuth oxychloride, platelet shaped substrates comprising an inorganic-organic mixed layer, and mixturesthereof.In addition to pearl luster pigments, metal effect pigments can also be used in thecontext of the present invention.The platelet-shaped metal substrate can in this case consist, in particular, of a puremetal and / or of a metal alloy. The metal substrate may preferably be selected fromthe group consisting of silver, aluminum, iron, chromium, nickel, molybdenum, gold,copper, zinc, tin, stainless steel, magnesium, steel, bronze, brass, titanium and theiralloys.In a further embodiment, the solid particles include fillers. All kind of fillers known inthe art can be used. Particularly functional fillers are used in the compositions.Thermally conductive materials help remove heat from the component and containthermally conductive filler(s) as functional filler(s). The filler material comprises asolid material with a thermal conductivity greater than that of the matrix material.Suitable filler materials for use in embodiments of the present invention include, forinstance aluminum powder, copper powder, nickel powder, or other metal powders;alumina powder, magnesia powder, beryllia powder, chromia powder, precipitatedsilica, fumed silica, titania powder, or other metal oxide powders; boron nitridepowder, aluminum nitride powder, or other metal nitride powders; born carbidepowder, titanium carbide powder, silicon carbide powder, or other metal carbidepowders; powders of Fe-Si alloys, Fe-Al alloys, Fe-Si-Al alloys, Fe-Si-Cr alloys, FeNi alloys, Fe-Ni-Co alloys, Fe-Ni-Mo alloys, Fe-Co alloys, Fe-Si-Al-Cr alloys, Fe-Si20 B alloys, Fe-Si-Co-B alloys; and other soft magnetic alloy powders; Mn-Zn ferrite,Mn-Mg-Zn ferrite, Mg-Cu-Zn ferrite, Ni-Zn ferrite, Ni-Cu-Zn ferrite, Cu-Zn ferrite, orother ferrites, and mixtures of two or more of the above-mentioned materials inaddition, the shape of the fillers can be, for instance, spherical, acicular, disk-like,rod-like, oblate, or irregular. When electrical insulation properties are required of thepresent composition, or the resultant cured silicone product obtained by curing thepresent composition, the filler is preferably a metal oxide powder, metal nitridepowder, or metal carbide powder, especially preferably, an alumina powder. Thereare no limitations concerning the average particle size of the filler, which ispreferably in the range of from 0.1 to 500 μm, and especially preferably, in the rangeof from 0.1 to 100 μm. When aluminum oxide particles are used as a thermallyconductive filler, it is preferably a mixture of (B1) spherical aluminum oxide particleswith an average particle size in the range of 1 to 50 μm and (B2) a spherical orirregular-shaped aluminum oxide particles with an average particle size of 0.1 to 50μm. Furthermore, in such a mixture, the content of the above-mentioned component(B1) is preferably in the range of from 30 to 90 wt % and the content of the above-mentioned component (B2) is preferably in the range of from 10 to 70 wt %calculated on sum components (B1) and (B2). In the composition, there are nolimitations concerning the content of the filler. However, in order to form a siliconecomposition of excellent thermal conductivity, its content in the composition in vol %preferably is at least 30 vol %, more preferably, in the range of from 30 to 90 vol %,still more preferably, in the range of from 60 to 90 vol %, and especially preferably,in the range of from 80 to 90 vol %. To form a silicone composition of excellentthermal conductivity, the content of the filler in wt % in the composition preferably isat least 50 wt %, more preferably, in the range of from 70 to 98 wt %, and especiallypreferably, in the range of from 90 to 97 wt %. The fillers may have different particlesizes and may be present not only individually but also in a mixture and, furthermore,may have been mutually coated with one another.Specifically, the content of the filler is in the range of from 500 to 2500 parts byweight, more preferably, in the range of from 500 to 2000 parts by weight, andespecially preferably, in the range of from 800 to 2000 parts by weight per 100 partsby weight of dispersion medium. This is due to the fact that when the content of thefiller is less than the lower limit of the above-mentioned range, the thermalconductivity of the resultant silicone compositions tends to decrease, and, on theother hand, when it exceeds the upper limit of the above-mentioned range, theviscosity of the resultant silicone compositions increases, and their handleabilitytends to deteriorate.The composition may further comprise a curing agent, which makes it possible toproduce a curable composition. When the composition is cured by means of ahydrosilation reaction, the curing agent is made up of a platinum catalyst and anorganopolysiloxane having an average of at least 2 silicon-bonded hydrogen atomsper molecule. The groups bonded to silicon atoms in the organopolysiloxane areexemplified by the same linear alkyl, branched alkyl, cyclic alkyl, aryl, aralkyl, andhalogenated alkyl groups as those mentioned above, preferably, by alkyl or arylgroups, and especially preferably, by methyl or phenyl.Suggested organopolysiloxanes include, for instance, dimethylpolysiloxane havingboth terminal ends of its molecular chain blocked by dimethylhydrogensiloxy groups,dimethylsiloxane-methylhydrogensiloxane copolymer having both terminal ends ofits molecular chain blocked by trimethylsiloxy groups, dimethylsiloxane-methylhydrogensiloxane copolymer having both terminal ends of its molecular chainblocked by dimethylhydrogensiloxy groups, organosiloxane copolymer consisting ofsiloxane units of the formula: (CH3)3 SiO1 / 2, siloxane units of the formula: (CH3)2HSiO1 / 2, and siloxane units of the formula: SiO4 / 2, and mixtures of two or more ofthe above-mentioned compounds.In the composition, the content of the organopolysiloxane having an average of atleast 2 silicon-bonded hydrogen atoms per molecule is the content necessary tocure the composition. Specifically, it is preferably sufficient to provide between 0.1mol and 10.0 mol, more preferably, between 0.1 mol and 5.0 mol, and especiallypreferably, between 0.1 mol to 3.0 mol of silicon-bonded hydrogen atoms from thecomponent per 1 mol of silicon-bonded alkenyl groups of the dispersion medium.This is due to the fact that when the content of this component is less than the lowerlimit of the above-mentioned range, the resultant silicone composition tends to failto completely cure, and, on the other hand, when it exceeds the upper limit of theabove-mentioned range, the resultant cured silicone product is extremely hard andtends to develop numerous cracks on the surface. In addition, the platinum catalystis a catalyst used to promote the curing of the present composition. Suggestedexamples of such catalysts include, for instance, chloroplatinic acid, alcoholsolutions of chloroplatinic acid, olefin complexes of platinum, alkenylsiloxanecomplexes of platinum, and carbonyl complexes of platinum. In the composition,the content of platinum catalyst is the content necessary for curing the presentcomposition. Specifically, it is sufficient to provide, in weight units, preferablybetween 0.01 ppm and 1,000 ppm, and particularly preferably between 0.1 ppm and500 ppm of platinum metal from the component relative to the amount of dispersion medium. This is due to the fact that when the content of the component is less thanthe lower limit of the above-mentioned range, the resultant silicone compositiontends to fail to completely cure, and, on the other hand, adding an amountexceeding the upper limit of the above-mentioned range does not significantlyimprove the cure rate of the the resultant silicone composition.When the composition is cured by means of a condensation reaction, curing agentis characterized by consisting of a silane having at least 2 silicon-bondedhydrolyzable groups per molecule or a partial hydrolyzate thereof, and, if needed, acondensation reaction catalyst. The silicon-bonded hydrolyzable groups in thesilane are exemplified by the same alkoxy, alkoxyalkoxy, acyloxy, ketoxime, alkenyl,amino, aminoxy, and amido groups as those mentioned above. In addition to theabove-mentioned hydrolyzable groups, examples of groups that can be bonded tothe silicon atoms of the silane include, for instance, the same linear alkyl, branchedalkyl, cyclic alkyl, alkenyl, aryl, aralkyl, and halogenated alkyl groups as thosementioned above. Suggested silanes or their partial hydrolyzates include, forinstance, methyltriethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, and ethylorthosilicate.In the composition, the content of the silane or its partial hydrolyzate is the contentnecessary to cure the present composition. Specifically, it is preferably in the rangeof from 0.01 to 20 parts by weight, and especially preferably, in the range of from0.1 to 10 parts by weight per 100 parts by weight of the dispersion medium. This isdue to the fact that when the content of the silane or its partial hydrolyzate is lessthan the lower limit of the above-mentioned range, the storage stability of theresultant composition deteriorates, and, in addition, its adhesive properties tend todecrease. On the other hand, when it exceeds the upper limit of the abovementioned range, the cure of the resultant composition tends to slow down. Inaddition, the condensation reaction catalyst is an optional component which is notessential when using silanes having, for instance, aminoxy, amino, ketoxime, andother hydrolyzable groups as curing agents. Suggested condensation reactioncatalysts include, for instance, tetrabutyl titanate, tetraisopropyl titanate, and otherorganic titanates; diisopropoxybis(acetylacetate)titanium,diisopropoxybis(ethylacetoacetate)titanium, and other chelate organotitaniumcompounds; aluminum tris(acetylacetonate), aluminum tris(ethylacetoacetate), andother organic aluminum compounds; zirconium tetra(acetylacetonate), zirconiumtetrabutyrate, and other organic zirconium compounds; dibutyltin dioctoate,dibutyltin dilaurate, butyltin-2-ethylhexoate, and other organotin compounds; tinnaphthenoate, tin oleate, tin butyrate, cobalt naphthenoate, zinc stearate, and othermetal salts of organic carboxylic acids; hexylamine, dodecylamine phosphates andother amine compounds or their salts; benzyltriethylammonium acetate, and otherquaternary ammonium salts; potassium acetate, lithium nitrate, and other lower fattyacid salts of alkali metals; dimethylhydroxylamine, diethylhydroxylamine, and otherdialkylhydroxylamines; and guanidyl-containing organosilicon compounds. In thecomposition, the content of the condensation reaction catalyst is variable, andshould be sufficient to cure the present composition. Specifically, it is preferably inthe range of from 0.01 to 20.00 parts by weight, and especially preferably, in therange of from 0.1 to 10.0 parts by weight per 100 parts by weight of the dispersionmedium. This is due to the fact that if the catalyst is essential, then a catalyst contentsmaller than the lower limit of the above-mentioned range tends to make it difficultfor the resultant composition to cure completely, and, on the other hand, when thecontent exceeds the upper limit of the above-mentioned range, the storage stabilityof the resultant composition tends to decrease.When the composition is cured by means of an organic peroxide-induced freeradical reaction, the curing agent suitably is an organic peroxide. Suggested organicperoxides include, for instance, benzoyl peroxide, dicumyl peroxide, 2,5-dimethylbis(2,5-t-butylperoxy)hexane, dit-butyl peroxide, and t-butylperbenzoate. Thecontent of the organic peroxides is the content necessary to cure the composition,specifically, it is preferably in the range of from 0.1 to 5.0 parts by weight per 100parts by weight of the organopolysiloxane of the above-mentioned dispersionmedium.In particular, when the present composition is cured by means of a hydrosilationreaction, to adjust the cure rate of the present composition and improve itshandleability, it is preferable to combine it with 2-methyl-3-butyn-2-ol, 2-phenyl-3-butyn-2-ol, 1-ethynyl-1-cyclohexanol, and other acetylene compounds; 3-methyl-3-penten-1-yne, 3,5-dimethyl-3-hexen-1-yne, and other ene-yne compounds; and, inaddition, hydrazine compounds, phosphine compounds, mercaptan compounds,and other cure reaction inhibitors. There are no limitations concerning the contentof the cure reaction inhibitors, however, preferably it is in the range of from 0.0001to 1.0 wt % relative to the amount of the present composition. In case the presentcomposition is curable, there are no limitations concerning the method of curing.The method, for instance, may involve molding the present composition and thenallowing it to stand at room temperature, or molding the present composition andthen heating it to 50 to 200°C. In addition, there are no limitations concerning thephysical characteristics of the thus obtained silicone, but suggested forms include,for instance, gels, low-hardness rubbers, or high-hardness rubbers.The invention further relates to a non-aqueous composition comprisinga) a polysiloxane having a plurality of siloxane groups and at least onecyclic carboxylic anhydride group or the hydrolysis product thereofcovalently linked to the polysiloxane,b) a dispersion medium, andc) solid filler particles,wherein the content of the filler particles is in the range of from 500 to 2500parts by weight per 100 parts by weight of the dispersion medium.In a preferred embodiment, the dispersion medium b) comprises a silicone which isdifferent from the polysiloxane a).It is particularly preferred that the dispersion medium b) is a crosslinkable silicone.The solid particles in the composition are preferably comprise at least one of fillersand pigments, as described above.In a preferred embodiment of the composition, component a) is present in anamount of 0.010 to 10.000 percent by weight, calculated on the total weight of thecomposition.In the composition, there are no limitations concerning the content of thepolysiloxane a). The content should be sufficient to treat the surface of the above20 described filler with the polysiloxane a) so as to improve its dispersibility in theresultant thermally conductive silicone composition, specifically, it is preferably inthe range of from 0.001 to 10.000 parts by weight per 100 parts by weight of thefiller and especially preferably, in the range of from 0.001 to 5 parts by weight per100 parts by weight of the filler. This is due to the fact that when the content of theabove-mentioned polysiloxane a) is less than the lower limit of the above-mentionedrange, addition of large quantities of the filler leads to a decrease in the moldabilityof the resultant silicone composition as well as to the precipitation and separationof the filler during storage of the resultant silicone composition and to a marked dropin its consistency. On the other hand, when it exceeds the upper limit of the above mentioned range, the physical properties of the resultant silicone composition tendto deteriorate.In some embodiments, the composition is implemented as a paint or coatingcomposition, as a molding composition, or as a paste or potting materials, gaskets,solder pasts, underfills, thermal interface materials such as thermal gap fillers, gappads, sil pads, phase change materials, thermal conductive grease, thermal gel,Thermal Clad materials, thermal encapsulants, adhesives, sealants material.If so desired, the composition may comprise other components, for example bindersor polymeric resins, reactive or non-reactive diluents, solvents, as well as customaryauxiliary additives. Examples of such additives include adhesion promoters, suchas 3-glycidyloxypropyltrimethoxysilane or 3-methacryloxypropyltrimethoxysilane,anti-foaming agents, thermal or UV stabilizers, rheological additives, and flow andleveling additives, crosslinkers, chain extender, reinforcing fillers, non-reinforcingfillers, plasticizers, flame retardants and heat resistant agents, such as triazolecompounds, water scavengers, biocides, curing accelerators, (fluorescent) dyes,inhibitors, antistatic agents, waxes catalysts and additives familiar to the personskilled in the art .The invention further relates to a process for dispersing solid particles in a nonaqueous composition, comprisinga) Providing a polysiloxane having a plurality of siloxane groups and atleast one cyclic carboxylic anhydride group or the hydrolysis productthereof covalently linked to the polysiloxane,b) Providing solid filler particles,c) Including the components provided in step a) and step b) in a nonaqueous composition comprising a dispersion medium to form adispersion base, andd) Subjecting the dispersion base to shear-force,wherein the content of the filler particles is in the range of from 500 to 2500 partsby weight per 100 parts by weight of the dispersion medium.ExamplesComparative DispersantSynthesis of an epoxy / amine adduct copolymer containing polysiloxane groups:A four-neck flask fitted with stirrer, thermometer, dropping funnel, reflux condenser,and nitrogen inlet tube was charged with a monoamino-functional polysiloxane asdescribed in example 1 of US9217083B2 (376.3 g) and 1,6-hexanediol diglycidylether (22.8 g) and heated to 140 °C under nitrogen. The epoxide conversion wasmonitored by means of 1H NMR. After full conversion of the epoxide groups, thereaction mixture was cooled to room temperature. GPC data Mn=5500 g / mol andPDI=2.0.Preparation of Si-H functional intermediatesThe synthesis of SiH functional silicone macromer of Butyl-D25MH Mw 2000 wascarried out as described in Example 1 of US8304077B2. The synthesis of ButylD38,5MH and Butyl-D65,5MH by adapting the ratio of Butyl Lithium toHexamethylcyclotrisiloxane monomer.Dispersant 1Reaction of Butyl-D25MH with a 30% molar excess of allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet181.15 g of Butyl-D25MH were placed and heated to 75 °C. Then 0.60 g of a 0.6 %solution of H2PtCl6 in xylene was added. Subsequently 18.85 g of allyl succinicanhydride were added via a dropping funnel. The reaction mixture was kept at100 °C for period of 3 hours. After this time the conversion of SiH groups was foundto be above 98%. Volatiles were removed by rotary evaporation at 130°C and 15mbar.GPC data of the resulting product: Mn 1759 g / mol, Mw 2232 g / mol, DPI 1.27Dispersant 2 Reaction of Butyl-D65,5MH with a 30% molar excess of allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogeninlet143.91 g of Butyl-D65.5MH were placed and heated to 75 °C. Then 0.53 g of a0.6 % solution of H2PtCl6 in xylene was added. Subsequently 6.09 g of allyl succinicanhydride were added via a dropping funnel. The reaction mixture was kept at100 °C for period of 3 hours. After this time the conversion of SiH groups was foundto be above 98%. Volatiles were removed by rotary evaporation at 130°C and 15mbar.GPC data of the resulting product: Mn 5630 g / mol, Mw 9153 g / mol, DPI 1.62Dispersant 3Reaction of Butyl-D38,5MH with a 30% molar excess of allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet140.98 g of Butyl-D38.5MH were placed and heated to 75 °C. Then 0.53 g of a 0.6 %solution of H2PtCl6 in xylene was added. Subsequently 9.02 g of allyl succinic anhydride were added via a dropping funnel. The reaction mixture was kept at100 °C for period of 3 hours. After this time the conversion of SiH groups was foundto be above 98%. Volatiles were removed by rotary evaporation at 130°C and 15mbar.GPC data of the resulting product: Mn 2745 g / mol, Mw 3399 g / mol, DPI 1.21Dispersant 4Step 1:Preparation of a siloxane having an average of one SiH group of the formulaMD38,5MH In a flask equipped with stirrer, thermometer and reflux condenser 9.46 g HMDSO(Hexamethyldisiloxane), 302.93 g D5, and 37.61 g MH2D6 were placed. The mixturewas heated to 75 °C. At this temperature, 3.5 g of catalyst K20 ex Clariant (Calciummontmorillonite treated with hydrochloric acid) were added to the mixture. Themixture was stirred at 80 °C for a period of 3 hours, followed by cooling to 50 °Cand further stirring at this temperature for 3 hours.1.75 g Harbolite 900 (AmorphousAlumina Silicate) filtration aid were added, and the mixture was stirred and filteredvia a pressure filter. The content of SiH groups was determined via determinationof the Iodine value, which was 8.14Step 2Reaction of the siloxane of step 1 with of allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet,141.72 g of the siloxane of step 1 were placed and heated to 75 °C. Then 0.53 g ofa 0.6 % solution of H2PtCl6 in xylene was added. Subsequently 8.28 g of allylsuccinic anhydride were added via a dropping funnel. The reaction mixture was keptat 100 °C for period of 3 hours. After this time the conversion of SiH groups wasfound to be above 98%. Volatiles were removed by rotary evaporation at 130°C andmbar.GPC data of the resulting product: Mn 1813 g / mol, Mw 5272 g / mol, DPI 2.91Dispersant 5Step 1Preparation of a siloxane having an average of one SiH group of the formulaMD65,5MHIn a flask equipped with stirrer, thermometer, and reflux condenser 5.68 g HMDSO,321.76 g D5, and 22.57 g MH2D6 were placed. The mixture was heated to 75 °C. Atthis temperature, 3.5 g of catalyst K20 were added to the mixture. The mixture wasstirred at 80 °C for a period of 3 hours, followed by cooling to 50 °C and furtherstirring at this temperature for 3 hours.1.75 g Harbolite 900 filtration aid were added,and the mixture was stirred and filtered via a pressure filter. The content ofSiH groups was determined via determination of the Iodine value, which was 4.81Step 2Reaction of the siloxane of step 1 with allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet144.99 g of the siloxane of step 1 were placed and heated to 75 °C. Then 0.53 g ofa 0.6 % solution of H2PtCl6 in xylene was added. Subsequently 5.01 g of allylsuccinic anhydride were added via a dropping funnel. The reaction mixture was keptat 100 °C for period of 3 hours. After this time the conversion of SiH groups wasfound to be above 98%. Volatiles were removed by rotary evaporation at 130°C andmbar.GPC data of the resulting product: Mn 2094 g / mol, Mw 8247 g / mol, DPI 3.94Dispersant 6Step 1Preparation of a siloxane having an average of one SiH group of the formulaMD86MHIn a flask equipped with stirrer, thermometer, and reflux condenser 4.35 g HMDSO,328.31 g D5, and 17.33 g MH 15 2D6 were placed. The mixture was heated to 75 °C. Atthis temperature, 3.5 g of catalyst K20 were added to the mixture. The mixture wasstirred at 80 °C for a period of 3 hours, followed by cooling to 50 °C and furtherstirring at this temperature for 3 hours.1.75 g Harbolite 900 filtration aid were added,and the mixture was stirred and filtered via a pressure filter. The content of SiHgroups was determined via determination of the Iodine value, which was 3.48.Step 2Reaction of the siloxane of step 1 with allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet146.34 g of the siloxane of step 1 were placed and heated to 75 °C. Then 0.53 g ofa 0.6 % solution of H2PtCl6 in xylene was added. Subsequently 3.66 g of allylsuccinic anhydride were added via a dropping funnel. The reaction mixture was keptat 100 °C for period of 3 hours. After this time the conversion of SiH groups wasfound to be above 98%. Volatiles were removed by rotary evaporation at 130°C andmbar.GPC data of the resulting product: Mn 2240 g / mol, Mw 11034 g / mol, DPI 4.93Dispersant 7Step 1Preparation of a siloxane having an average of one SiH group of the formulaMD106MHIn a flask equipped with stirrer, thermometer, and reflux condenser 3.55 g HMDSO,332.33 g D5, and 14.12 g MH 2D6 were placed. The mixture was heated to 75 °C. Atthis temperature, 3.15 g of catalyst K20 were added to the mixture. The mixture was stirred at 80 °C for a period of 3 hours, followed by cooling to 50 °C and furtherstirring at this temperature for 3 hours.1.75 g Harbolite 900 filtration aid wereadded,and the mixture was stirred and filtered via a pressure filter. The content ofSiH groups was determined via determination of the Iodine value, which was 2.95.Step 2Reaction of the siloxane of step 1 with allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet146.89 g of the siloxane of step 1 were placed and heated to 75 °C. Then 0.53 g ofa 0.6 % solution of H2PtCl6 in xylene was added. Subsequently 3.11 g of allylsuccinic anhydride were added via a dropping funnel. The reaction mixture was keptat 100 °C for period of 3 hours. After this time the conversion of SiH groups wasfound to be above 98%. Volatiles were removed by rotary evaporation at 130°C andmbar.GPC data of the resulting product: Mn 2255 g / mol, Mw 13177 g / mol, DPI 5.37Dispersant 8Step 1Preparation of a siloxane having an average of one SiH group of the formulaMD133MHIn a flask equipped with stirrer, thermometer, and reflux condenser 2.84 g HMDSO,335.86 g D5, and 11.30 g MH 2D6 were placed. The mixture was heated to 75 °C. Atthis temperature, 3.15 g of catalyst K20 were added to the mixture. The mixture wasstirred at 80 °C for a period of 3 hours, followed by cooling to 50 °C and furtherstirring at this temperature for 3 hours.1.75 g Harbolite 900 filtration aid were added,and the mixture was stirred and filtered via a pressure filter. The content of SiHgroups was determined via determination of the Iodine value, which was 2.54.Step 2Reaction of the siloxane of step 1 with allyl succinic anhydrideIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet147.31 g of the siloxane of step 1 were placed and heated to 75 °C. Then 0.53 g ofa 0.6 % solution of H2PtCl6 in xylene was added. Subsequently 2.69 g of allylsuccinic anhydride were added via a dropping funnel. The reaction mixture was keptat 100 °C for period of 3 hours. After this time the conversion of SiH groups wasfound to be above 98%. Volatiles were removed by rotary evaporation at 130°C andmbar.GPC data of the resulting product: Mn 2717 g / mol, Mw 16878 g / mol, DPI 6.21Dispersant 9Hydrolysis of Dispersant 5 with deionized waterIn a flask equipped with stirrer, thermometer, reflux condenser and nitrogen inlet248.29 g of dispersant 5 described above and 1.7 g of deionized water were placed.The mixture was stirred and heated at 70 °C for a period of 10 hours. After this time89 mole-% of the cyclic carboxylic anhydride groups were found to be hydrolyzedto dicarboxylic acid groups. Volatiles were removed by rotary evaporation at 130°Cand 15 mbar.Dispersant 10Salt formation of Dispersant 9In a glass beaker 116.19 g of dispersant 9 were mixed with 3.81 g of N,N-dibutylethanol amine.In the following the application of dispersing agents in addition curing RTV siliconeformulations is described.For the preparation of addition curing RTV silicone compositions a dual asymmetriccentrifuge mixer, Speedmixer DAC 400.1 FVZ, Hauschild GmbH & Co. KG wasused.Raw Materials:• Addition-curing, RTV-2 silicone rubber Part A (SilGel 612A, Wacker) –Vinylpolydimethylsiloxane and additives• Addition-curing, RTV-2 silicone rubber Part B (SilGel 612 B, Wacker) SiH -functional polydimethylsiloxanes and Polydimethylsiloxane with functionalgroups and additives including platinum catalyst• Adhesion Promoter - Methacryloxypropyltrimethoxysilane• Filler 1 – Aluminum oxide – average particle size 1.4 µm• Filler 2 – Aluminum oxide – average particle size 45.0 µm• Filler 3 – Aluminum oxide – average particle size 0.2 mmFor the determination of the curing behavior of the silicone composition and theinfluence of the dispersing agent on that application property the formulation wasevaluated in a non-filled system. Part A and B were formulated separately in a PESpeedmixer cup by dosing all respective raw materials of Part A or Part B andhomogenized for 30sec at 2.500rpm. Afterwards Part A and Part B were mixed witha mixing ratio A: B of 1.5 : 1 with the Speedmixer for 30sec at 2.000rpm and werestored in the oven at 100°C until the formulation was cured. The formulations wereobserved at intervals of 60 sec to evaluate the curing stage. The time when the firstskin was built on the surface of the formulation is defined as the skin forming time.The time of the fully cured formulation with no further change of hardness andviscosity is defined as the curing time.TableApplication results non-filled silicone composition:From the table above it can be concluded that the comparative dispersantcompletely prevents curing of the silicone rubber. The dispersants according to theinvention have only a weak influence on the curing properties, which can beadjusted by the amount of curing catalyst.For the evaluation of the influence of the dispersants on the viscosity of highly filledsilicone compositions aluminum oxide filled addition curing RTV-2 compositionswere formulated.Part A of the RTV 2 composition was formulated in a PE Speedmixer cup by dosingthe silicone gel, the adhesion promoter and the dispersing agent and homogenizedthem with the Speedmixer for 30sec at 2.500rpm. Afterwards the Al2O3 filler wasdosed in one shot and homogenized for 30sec at 2.500rpm.The viscosity of the formulated Part A was determined with a rheometer, AntonPaarMCR 201 under the following conditions: PP 25, shear rate 0,1 – 100 s-1, 1,0 mmgap, 23 °C, sample trimming. In particular, the viscosity at 1 s-1 and 10 s-1 wereobserved to describe the viscosity of the filled and modified composition.Part B of the RTV 2 composition was formulated in a PE Speedmixer cup by dosingthe silicone gel and the dispersing agent and homogenized them with theSpeedmixer for 30sec at 2.500rpm. Afterwards the Al2O3 filler was dosed in oneshot and homogenized for 30sec at 2.500rpm.Part A and Part B were mixed with the Speedmixer for 30 sec at 2.000rpm and werestored in the oven at 100°C until the formulation was cured. The formulations wereobserved in intervals of 60 sec to evaluate the curing stage analogue to the unfilledsystem.TableApplication results filled silicone composition:From the table above it can be concluded that the effect of the dispersantsaccording to the invention on viscosity reduction in the highly filled siliconecomposition is significantly stronger compared to the comparative dispersant. Incontrast to the comparative dispersant, the dispersants according to the inventionto not prevent curing.One of the major applications for thermal conductive filler filled siliconecompositions are thermal interface materials (TIM) and the application of thosematerials on copper substrates. For this application, the corrosion properties of thedispersants were evaluated on the respective substrate. The pure dispersant wasdropped on copper, covered with a cotton pad and stored in a climate chamber for14 days at 55°C and 80% relative humidity. In a second test the non-filled siliconecomposition including the dispersant was applied with a spatula on copper coveredwith a cotton pad and stored in the climate chamber for 14 days at 55°C and 80%rel. humidity. The corrosion of the copper substrate was evaluated visually andranked on a scale of 1 to 6.TableFrom the table above it can be concluded that the dispersants according to theinvention cause less corrosion than the comparative dispersant on a coppersubstrate.The influence of dispersants on the viscosity reduction with different filler types wasevaluated by modifying Part A of the described formulation with calcium carbonate,boron nitride and aluminiumhydroxide and the dispersing additives. The viscosity ofthe formulated Part A was determined with a rheometer, AntonPaar MCR 201 underthe following conditions: PP 25, shear rate 0,1 – 100 s-1, 1,0 mm gap, 23 °C, sampletrimming. The viscosity at 1 s-1was recorded.Fillers:Calcium Carbonate – CaCO3 - mean particle size 5µmAluminumhydroxide – Al(OH)3 – mean partice size 12µmBoron Nitride – BN – mean partice size 16 µmFormulation Calcium Carbonate:TableFormulation AluminumhydroxideTableFormulation Boron NitrideTableThe impact of the comparative and inventive dispersing additives on the viscosityreduction of the composition is shown in the following table:TableFrom the Table above it can be concluded that Dispersant 5 significantly reducesthe viscosity of addition curing RTV-2 compositions with different fillers.

Claims

1. The use of a polysiloxane having a plurality of siloxane groups and at least one cyclic carboxylic anhydride group or the hydrolysis product thereof covalently linked to the polysiloxane, as a dispersing agent for solid filler particles in a non-aqueous composition comprising a dispersion medium, wherein the content of the filler particles is in the range of 500 to 2500 parts by weight per 100 parts by weight of the dispersion medium.

2. The use according to claim 1, wherein the cyclic carboxylic anhydride group forms a 5-membered ring.

3. The use according to claim 1 or 2, wherein the cyclic carboxylic anhydride group or the hydrolysis product thereof is linked to the polysiloxane via an Si-C bond.

4. The use according to any one of the preceding claims, wherein on average 0.7 to 3.0 cyclic carboxylic anhydride groups or the hydrolysis product thereof are covalently linked to a polysiloxane molecule.

5. The use according to any one of the preceding claims, wherein the nonaqueous composition comprises a dispersion medium which is different from the polysiloxane having a plurality of siloxane groups and at least one cyclic carboxylic anhydride group or the hydrolysis product thereof.

6. The use according to claim 5, wherein the dispersion medium comprises a silicone.

7. The use according to any one of the preceding claims, wherein the non30 aqueous composition is used as a thermal interface material.

8. The use according to claim 7, wherein the non-aqueous composition is used as thermal interface material in an electronic component.

9. A non-aqueous composition comprising a) a polysiloxane having a plurality of siloxane groups and at least one cyclic carboxylic anhydride group or the hydrolysis product thereof covalently linked to the polysiloxane, b) a dispersion medium, and c) solid filler particles, wherein the content of the filler particles is in the range of from 500 to 2500 parts by weight per 100 parts by weight of the dispersion medium.

10. The composition according to claim 9, wherein the dispersion medium b) comprises a silicone which is different from the polysiloxane a).

11. The composition according to claim 10, wherein the silicone is a crosslinkable silicone.

12. The composition according to any one of the preceding claims 9 to 11, wherein the average particle size of solid filler particles is in the range of 0.1 to 500.0 μm.

13. The composition according to any one of the preceding claims 9 to 12, wherein the solid filler particles comprise aluminum oxide particles.

14. The composition according to claim 13, wherein the aluminum oxide particles comprise at least one of spherical aluminum oxide particles having an average particle size in the range of 1.0 to 50.0 μm and irregular-shaped aluminum oxide particles having an average particle size in the range of 0.1 to 50.0 μm.

15. The composition according to any one of the preceding claims 7 to 14, wherein component a) has a number average molecular weight Mn in the range of 500 to 10000 g / mol.

16. The composition according to any one of the preceding claims 7 to 15, wherein component a) is present in an amount of 0.010 to 10.000 percent by weight, calculated on the total weight of the composition.

17. A process for dispersing solid filler particles in a non-aqueous composition, comprising a) Providing a polysiloxane having a plurality of siloxane groups and at least one cyclic carboxylic anhydride group or the hydrolysis product thereof covalently linked to the polysiloxane, b) Providing solid filler particles, c) Including the components provided in step a) and step b) in a nonaqueous composition comprising a dispersion medium to form a dispersion base, and d) Subjecting the dispersion base to shear-force, wherein the content of the filler particles is in the range of from 500 to 2500 parts by weight per 100 parts by weight of the dispersion medium.