Patent Description:
Aqueous dispersions of polyurethanes are well known as basis for the production of coating compositions. They may be used for protective or decorative coating, optionally in combination with additives like colouring agents, pigments, matting agents, and the like. Polyurethanes can possess many desirable properties such as good chemical resistance, water resistance, solvent resistance, toughness, abrasion resistance, durability.

As is well known in the art, aqueous polyurethane dispersions are particularly advantageously prepared by dispersing an isocyanate-terminated polyurethane prepolymer bearing ionic dispersing groups into an aqueous medium and then reacting the prepolymer with an active hydrogen containing chain extender while dispersed in the aqueous medium. See e.g. <CIT> and <CIT>.

Anti-soiling and cleanability of a coating are desired properties, especially for coatings that come into contact with humans, of which leather and artificial leather, which are flexible sheet-like materials, are a good example such as car seats and other automotive interior parts, such as instrument panels, sun visors and gaiters.

Anti-soiling and cleanability are closely related to anti-graffiti properties. Anti-graffiti properties are often accomplished by incorporating fluorocarbons in the coating because fluorocarbons give hydrophobicizing and oleophobicizing properties. However, such approach is not working well for flexible sheet-like materials, as coatings thereon need to be flexible as well, and the fluorocarbon groups seem to be less active with flexible coatings compared to their activity with hard coatings.

Another approach to achieve anti-soiling and cleanability is to incorporate silicones/siloxanes in a coating. This yields hydrophobicizing properties but no oleophobicizing properties to the coating.

<CIT> describes the process for coating a sheet-like substrate using aqueous polyurethane dispersions in which polydimethylsiloxane together with long alkyl or alkeyl groups are introduced as side chains of the polyurethane.

<CIT> describes the incorporation of linear polydimethylsiloxanediol into a polyurethane, using acetone as solvent, which is later distilled off.

<CIT> describes the incorporation of linear polydimethylsiloxanediol into a polyurethane, in which a certain amount of silicon compared to the weight of the polyurethane is incorporated.

<CIT> describes film-forming polymers based on silicone-modified polyurethanes for use in hair setting compositions, in which linear polysiloxanediamine is used as a chain extender.

<CIT> describes the incorporation of linear polydimethylsiloxanediamines, with molecular weights of less than <NUM>/mol, into a polyurethane.

<CIT> describes the incorporation of linear polydimethylsiloxanediols into a polyurethane in mini-emulsion.

<CIT> describes aqueous polyurethane dispersions with the incorporation of linear hydroxyalkyl-functional polydimethylsiloxane into the polyurethane, in which the polyurethane is finally made hydroxyl-functional before dispersing into water.

<CIT> describes aqueous polyurethane dispersion with the incorporation of monocarbinol terminated polydimethylsiloxane into the polyurethane.

<CIT> discloses a polyurethane resin prepared from a polyol, a chain extender, a diisocyanate and a polydimethylsiloxane having dibasic alcohol groups.

The incorporation of linear polydimethylsiloxanes into a polyurethane gives hydrophobicizing properties to a surface of the dried film of those aqueous polyurethane dispersions. To achieve such properties a certain amount of polydimethylsiloxanes needs to be incorporated. It has been found that the amount of polydimethylsiloxanes that needs to be incorporated to obtain such properties, such as anti-soiling properties or cleanability, can be a lower amount when the polydimethylsiloxane is not a linear polydimethylsiloxane, with hydroxyl or amine group at the termini, but a diol with the polydimethylsiloxane as a side group. These components are also called mono-dicarbinol terminated polydimethylsiloxanes.

The present invention provides a process for the preparation of an aqueous polydialkylsiloxane-polyurethane dispersion wherein the polydialkylsiloxane is present as a side chain of the polyurethane resin, comprising the steps of:.

Polyurethane dispersions are generally made by dispersing a polyurethane prepolymer into water. Suitable prepolymers may be made using isocyanate components. These isocyanates are reacted with polyols. Preferred prepolymers may be made with aliphatic di-isocyanates, aromatic di-isocyanates, or a mixture of aromatic and aliphatic di-isocyanates, such as toluene-<NUM>,<NUM>-diisocyanate, toluene-<NUM>,<NUM>-diisocyanate and mixtures thereof, diphenylmethane-<NUM>,<NUM>-diisocyanate, <NUM>,<NUM>-phenylenediisocyanate, dicyclohexylmethane-<NUM>,<NUM>'-diisocyanate, <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclo-hexylisocyanate, <NUM>,<NUM>-hexyldiisocyanate, <NUM>,<NUM>-pentyldiisocyanate, <NUM>,<NUM>-bis(isocyanatomethyl)cyclohexane, <NUM>,<NUM>,<NUM>-trimethyl-<NUM>,<NUM>-diisocyanatohexane (<NUM>,<NUM>,<NUM>-isomer, <NUM>,<NUM>,<NUM>-isomer, or mixture thereof), <NUM>,<NUM>-cyclohexyldiisocyanate, norbonyldiisocyanate, p-xylylene diisocyanate, <NUM>,<NUM>'-diphenylmethane diisocyanate, and/or <NUM>,<NUM>-naphthylene diisocyanate. Mixtures of polyisocyanates can be used and also polyisocyanates which have been modified by the introduction of urethane, allophanate, urea, biuret, carbodiimide, uretonimine or isocyanurate residues. Particularly preferred polyisocyanates include aliphatic polyisocyanates such as <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclohexylisocyanate, hexamethylene diisocyanate and dicyclohexyl-methane-<NUM>,<NUM>'-diisocyanate.

Polymeric polyols having molecular weights in the range of <NUM> to <NUM> which may be used in the preparation of the prepolymer particularly include diols and triols and mixtures thereof but higher functionality polyols may be used as well, for example as minor components in admixture with diols. The polyols may be members of any of the chemical classes of polymeric polyols used or proposed to be used in polyurethane formulations. Preferred polyols are selected from the group of polyester polyols, polyesteramide polyols, polyether polyols, polythioether polyols, polycarbonate polyols, polyacetal polyols, polyolefin polyols or mixtures thereof. Preferred polyol molecular weights are from <NUM> to <NUM>. Polyols having molecular weights below <NUM> which may optionally be used in the preparation of the prepolymer particularly include diols and triols and mixtures thereof but higher functionality polyols may be used. Examples of such lower molecular weight polyols include ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, bis (hydroxyethyl) terephthalate, neopentylglycol, trimethylol propane, cyclohexane dimethanol, furan dimethanol, glycerol and the reaction products, up to molecular weight <NUM>, of such polyols with propylene oxide and/or ethylene oxide.

Polysiloxane components A, with <NUM> hydroxyl groups attached to an alkyl group on one end of the linear polydialkylsiloxane chain and an alkyl group on the other end of the linear polydialkylsiloxane chain, are short alkyl diols, of between <NUM> and <NUM> carbon atoms, with one alkyl, of between <NUM> and <NUM> carbon atoms, terminated polydialkylsiloxane side chain, in which there are more than <NUM>, preferably more than <NUM>, and most preferably more than <NUM> alkylsiloxane repetitive units in the polydialkylsiloxane side chain. These components are also called mono-dicarbinol terminated polydialkylsiloxanes. Preferably the polydialkylsiloxane side chain is a polydimethylsiloxane chain. Examples are MCR-C63 (molecular weight <NUM> Dalton), MCR-C62 (molecular weight <NUM> Dalton) and MCR-<NUM> (molecular weight <NUM> Dalton) from Gelest, X-<NUM>-176DX (molecular weight <NUM> Dalton), X-<NUM>-176F (molecular weight <NUM> Dalton) and X-<NUM>-176GX-A (molecular weight <NUM> Dalton) from Shin-Etsu Chemical Company and Silmer OHT A0 (molecular weight <NUM> Dalton) from Siltech Corporation. Here, the molecular weight is related to the number of dimethylsiloxane repetitive units in the polydimethylsiloxane side chain, as the weight of the carbinol and alkyl groups is modest compared to the weight of the polydimethylsiloxane, in which the formula weight of the repetitive dimethylsiloxane unit is approximately <NUM> Dalton.

In the context of the present invention, component A has a molecular weight of above <NUM> Dalton, preferably above <NUM> Dalton, most preferably <NUM> Dalton or more. The molecular weight of mono-dicarbinol terminated polydialkylsiloxanes is generally determined from the measured OH-value (mg KOH/g), which can be used to calculate the functional group equivalent weight (FGEW), according to formula FGEW (g/mol) = <NUM>/OH-value. Since for mono-dicarbinol terminated polydialkylsiloxanes there are two hydroxyl groups per molecule, the molecular weight is double of the FGEW.

In the context of the present invention, the amount of component A is generally between <NUM> weight% and <NUM> weight% compared to total weight of the polyol and isocyanate components in the prepolymer. Preferably the amount of component A is at least <NUM> wt%, more preferably at least <NUM> wt% and most preferably at least <NUM> wt%, compared to total weight of the polyol and isocyanate components in the prepolymer. Preferably the amount of component A is at most <NUM> wt%, more preferably at most <NUM> wt%, most preferably at most <NUM> wt% or even <NUM> wt% compared to total weight of the polyol and isocyanate components in the prepolymer.

In the context of the present invention, the component A is reacted simultaneously with all the other reactive components in the prepolymer or is reacted first with (part of) the isocyanate component, prior to the reaction with other isocyanate-reactive components. Hence random or block copolymers can be prepared. Preparation of random block copolymers is more convenient although block copolymer preparation allows to control more easily complete reaction of component A with isocyanate.

Dispersibility of the polyurethanes in water is generally achieved by incorporating hydrophilic groups into the prepolymer. For this reason other polyols are generally present during the prepolymer formation namely polyols with hydrophilic groups and/or polyols that have an additional functional group that is capable of forming a salt such as a polyethoxy diol, a poly(ethoxy/propoxy) diol, a diol containing a pendant ethoxy or (ethoxy/propoxy) chain, a diol containing a carboxylic acid, a diol containing a sulfonic group, a diol containing a phosphate group, a polyethoxy mono-ol, a poly(ethoxy/propoxy) mono-ol, a mono-ol containing a pendant ethoxy or (ethoxy/propoxy) chain, a mono-ol containing a carboxylic acid or a sulphonic acid or salt, or mixtures thereof. A diol containing a carboxylic acid include carboxyl group containing diols and triols, for example dihydroxy alkanoic acids of the formula: R-C-(CH<NUM>-OH)<NUM>-COOH wherein R is hydrogen or alkyl. Examples of such carboxyl containing diols are <NUM>,<NUM>-dimethylolpropionic acid and <NUM>,<NUM>-dimethylolbutanoic acid. Other useful acid group containing compounds include amino carboxylic acids, for example lysine, cysteine and <NUM>,<NUM>-diaminobenzoic acid and sulfonic acids, for example <NUM>,<NUM>-diaminobenzene-<NUM>,<NUM>-disulphonic acid.

The carboxylic acid functions are generally neutralized with a volatile tertiary amine neutralizing agent before or during dispersion of the polyurethane prepolymer into water; yet other known neutralizing agents can be used as well, such as alkaline metal hydroxides. Both the polyurethane and the tertiary amine functional urethane polymer or oligomer or dispersion thereof may contain additional functional groups with the objective to improve the waterdispersibility, to improve adhesion to substrates during application, for performance reasons, or as potential sites for crosslinking. Suitable functions are polyalkoxy functions with a large concentration of ethoxy functions, tertiary amine or quaternary amine functions, perfluoro functions, incorporated silicon functions, hydrazide functions or hydrazone functions, ketone, acetoacetate, or aldehyde functions, or mixtures thereof.

The conversion of any acid groups present in the prepolymer to anionic groups may be effected by neutralising the said acidic groups before, after or simultaneously with formation of the aqueous dispersion. Suitable neutralising agents include tertiary amines such as tripropylamine, dimethyl butyl amine, dimethyl ethanol amine, diethyl ethanol amine, triethylamine, <NUM>-amino-<NUM>-methyl-<NUM>-propanol and N-ethylmorpholine and include alkaline metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide or non-volatile tertiary amines such as N-butyldiethanolamine or N,N-bis[<NUM>-(dimethylamino)propyl]-N',N'-dimethylpropane-<NUM>,<NUM>-diamine or mixtures thereof.

The prepolymer may contain between <NUM>% and <NUM> weight% co-solvents to achieve a low(er) viscosity, but preferably the prepolymer contains less than <NUM> weight% co-solvent. If used, suitable co-solvents are N-ethyl pyrrolidine, acetone, <NUM>-butanone, <NUM>,<NUM>'-ethylenedioxydiethyl bis(<NUM>-ethylhexanoate and dipropylene glycol dimethyl ether. Not only are these co-solvents used to reduce the viscosity of the prepolymer, but also do these allow for a more convenient handling during the dispersion step.

Polyurethane prepolymers useful in the practice of the present invention may be prepared in conventional manner by reacting a stoichiometric excess of the organic polyisocyanate with the polymeric polyol having a molecular weight in the range <NUM> to <NUM> and the other required isocyanate-reactive compounds under substantially anhydrous conditions at a temperature between about <NUM> and about <NUM> until reaction between the isocyanate groups and the hydroxyl groups is substantially complete. The polyisocyanate and the active hydrogen containing components are suitably reacted in such proportions that the ratio of number of isocyanate groups to the number of hydroxyl groups is in the range from about <NUM>:<NUM> to about <NUM>:<NUM>, preferably within the range of from <NUM>:<NUM> to <NUM>:<NUM>. If desired, catalysts, such as bismuth carboxylate, zinc carboxylate, dibutyltin dilaurate, aluminium chelate, zirconium chelate, stannous octoate or triethylenediamine, may be used to assist prepolymer formation.

Prepolymers useful in the practice of the present invention should be substantially liquid under the conditions of the dispersing step, which means that these prepolymers should have a viscosity below <NUM>,<NUM> mPa. s at a temperature of <NUM>, measured using a Brookfield LVF Viscometer.

The present invention includes generally the use of an extension agent, which is used to build the molecular weight of the polyurethane prepolymer by reacting the extension agent with the isocyanates functionality of the polyurethane prepolymer. The active hydrogen containing extension agent which is reacted with the prepolymer is suitably a polyol, an amino alcohol, ammonia, a primary or secondary aliphatic, alicyclic, aromatic, araliphatic or heterocyclic amine especially a diamine, hydrazine or a substituted hydrazine. Water-soluble extension agents are preferred, and water itself may be effective. Examples of suitable extension agents useful herein include ethylene diamine, diethylene triamine, triethylene tetramine, propylene diamine, butylene diamine, hexamethylene diamine, cyclohexylene diamine, piperazine, <NUM>-methyl piperazine, phenylene diamine, bis(<NUM>-aminopropylamine), sodium <NUM>-[(<NUM>-aminoethyl)amino]ethanesulfonate, tolylene diamine, xylylene diamine, tris (<NUM>-aminoethyl) amine, <NUM>,<NUM>'-dinitrobenzidine, <NUM>,<NUM>'methylenebis (<NUM>-chloraniline), <NUM>,<NUM>'-dichloro-<NUM>,<NUM>'biphenyl diamine, <NUM>,<NUM>-diaminopyridine, <NUM>,<NUM>'-diaminodiphenylmethane, menthane diamine, m-xylene diamine, <NUM>-amino-<NUM>,<NUM>,<NUM>-trimethyl-cyclohexanemethyl-amine, sodium <NUM>-[(<NUM>-aminoethyl)amino]ethanesulfonate (e.g. Vestamin A95 from Evonik), lysine, <NUM>-(<NUM>-aminoethylamino)propane-<NUM>-sulfonic acid, polymer of <NUM>-(<NUM>-aminoethylamino)propane-<NUM>-sulfonic acid (Poly-EPS from Raschig), sodium N-(<NUM>-aminoethyl)-B-alaninate (PUD Salt from BASF), amine terminated polyethers such as, for example, Jeffamine D-<NUM> from Huntsman Chemical Company, and adducts of diethylene triamine with acrylate or its hydrolyzed products. Also suitable are materials such as hydrazine, azines such as acetone azine, substituted hydrazines such as, for example, dimethyl hydrazine, <NUM>,<NUM>-hexamethylene-bis-hydrazine, carbodihydrazine, hydrazides of dicarboxylic acids and sulfonic acids, adipic acid mono- or dihydrazide, oxalic acid dihydrazide, isophthalic acid dihydrazide, tartaric acid dihydrazide, <NUM>,<NUM>-phenylene disulfonic acid dihydrazide omega-amino-caproic acid dihydrazide, hydrazides made by reacting lactones with hydrazine such as gamma-hydroxylbutyric hydrazide, bis-semi-carbazide, bis-hydrazide carbonic esters of glycols such as any of the glycols mentioned above. The amount of extension agent employed should be approximately equivalent to the free-NCO groups in the prepolymer, the ratio of active hydrogens in the chain extender to NCO groups in the prepolymer preferably being in the range from <NUM>:<NUM> to <NUM>:<NUM>. Of course when water is employed as the extension agent, these ratios will not be applicable since the water, functioning both as extension agent and dispersing medium, will be present in a gross excess relative to the free-NCO groups.

While polyurethane prepolymers may retain some isocyanate reactivity for some period of time after dispersion, for purposes of the present invention, a polyurethane prepolymer dispersion is considered to be a fully reacted polyurethane polymer dispersion. Also, for purposes of the present invention, a polyurethane prepolymer or polyurethane polymer can include other types of structures such as, for example, urea groups.

The aqueous polyurethane dispersion comprises at least <NUM> wt%, preferably at least <NUM> wt% of polyurethane polymer particles based on total mass of the dispersion. As conventionally done by the skilled person, the weight percentage is calculated beforehand, taking into account which components evaporate and which components do not evaporate. The solids percentage is at a later stage measured to confirm: thereto, a small amount is weighted, then put in an oven at <NUM> during one hour and the remaining amount is measured. In this control step, a higher or longer temperature/time regime can be chosen as well, if there are slowly evaporating components present.

If desired, amounts of emulsifiers, defoamers, flame retardants, thickeners, stabilizers, wetting agents, biocides, anti-oxidants and/or anti-settling agents may be included in the prepolymer or the water phase, or may be added to the aqueous polyurethane dispersion.

The prepolymer thus prepared and a water phase are being mixed to obtain a polyurethane dispersion, wherein the extension agent, if the extension agent is different from water, can be added to the water phase prior to the dispersing step, or can be added during the dispersing step, or can be added to the dispersion after the dispersing step. Optionally, neutralization agents, undiluted or with water diluted additives, like emulsifiers, defoamers, flame retardants, thickeners, stabilizers, anti-oxidants and/or anti-settling agents can be added to the water phase or to the dispersion.

The viscosity of the aqueous polyurethane dispersion of the invention is generally lower than <NUM> mPa. s, preferably lower than <NUM>, more preferably lower than <NUM>, and most preferably lower than <NUM> mPa. s, as measured at <NUM> using a Brookfield LVF Viscometer.

The invention also relates to the use of the aqueous polyurethane dispersion for the coating of a very wide range of substrates, preferably wood, paper, textile, plastic and metal, in particular of flexible sheet-like substrates such as leather. The present invention also relates to the substrates coated with the aqueous polyurethane dispersion according to the invention. In general said coating or film has a thickness of between <NUM> micrometer and <NUM> millimeter, and more preferably between <NUM> micrometer and <NUM> micrometer and most preferably between <NUM> micrometer and <NUM> micrometer. The invention furthermore relates to a process for the coating of substrates, in particular of leather, which is characterized in that the aqueous polyurethane dispersion according to the invention is applied to substrates. Suitable application techniques are known methods, such as application with a doctor blade, spraying, casting or coating by means of a reverse roll coater.

The above described specific embodiments are all embodiments in accordance with the present invention. The various embodiments may be mutually combined. A feature described for one particular embodiment maybe taken up, incorporated in or otherwise combined with other particular embodiments unless the laws of physics would forbid such combinations.

The present invention will be further elaborated by the following non-limiting working examples. Parts and percentages of components referred to in these working examples are drawn to the weight of the total composition wherein these components are present, like in the other parts of the description and claims, unless otherwise indicated.

Under a nitrogen atmosphere a mixture of <NUM> of <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclohexylisocyanate and <NUM> of X-<NUM>-176F (a mono-dicarbinol terminated polydimethylsiloxane from Shin-Etsu Chemical Company; molecular weight <NUM> Dalton) together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst were reacted with each other for one hour at <NUM>. The reaction was cooled down and the amount of remaining NCO was measured.

Under a nitrogen atmosphere a mixture <NUM> of a polycarbonate diol, derived from hexanediol, with a molecular weight of <NUM>, <NUM> of dipropylene glycol dimethyl ether and <NUM> of dimethylolpropanoic acid were heated to <NUM> while stirring. <NUM> of <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclohexylisocyanate and <NUM> of the reaction product of the afore-mentioned <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclohexylisocyanate and X-<NUM>-176F, together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst, were added and the mixture was heated to <NUM> and stirred for <NUM> hours to form a polyurethane prepolymer. The reaction was cooled down and the amount of remaining NCO was measured. A mixture was made of <NUM> of the prepolymer and <NUM> of triethylamine, and this mixture was dispersed into a water phase consisting of <NUM> of water, <NUM> of Provichem 2588P (a <NUM>% solution of sodium dioctyl sulfosuccinate in dipropylene glycol dimethyl ether, from Proviron Functional Chemicals NV) and <NUM> of hydrazine hydrate. The dispersion was stirred for an additional <NUM> minutes. The solids content of the dispersion was <NUM>%. The viscosity of the dispersion was <NUM> mPa. s, as measured at <NUM> using a Brookfield LVF Viscometer. Of the total solids content of the dispersion, <NUM> weight% comes from the mono-dicarbinol terminated polydimethylsiloxane.

Under a nitrogen atmosphere a mixture <NUM> of a polycarbonate diol, derived from hexanediol, with a molecular weight of <NUM>, <NUM> of dipropylene glycol dimethyl ether, <NUM> of X-<NUM>-176F (a mono-dicarbinol terminated polydimethylsiloxane from Shin-Etsu Chemical Company; molecular weight <NUM> Dalton) and <NUM> of dimethylolpropanoic acid were heated to <NUM> while stirring. <NUM> of dicyclohexyl-methane-<NUM>,<NUM>'-diisocyanate together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst were added and the mixture was heated to <NUM> and stirred for <NUM> hours to form a polyurethane prepolymer. The reaction was cooled down and the amount of remaining NCO was measured. A mixture was made of <NUM> of the prepolymer and <NUM> of triethylamine, and this mixture was dispersed into a water phase consisting of <NUM> of water, <NUM> of Provichem 2588P (a <NUM>% solution of sodium dioctyl sulfosuccinate in dipropylene glycol dimethyl ether, from Proviron Functional Chemicals NV) and <NUM> of hydrazine hydrate. The dispersion was stirred for an additional <NUM> minutes. The solids content of the dispersion was <NUM>%. The viscosity of the dispersion was <NUM> mPa. s, as measured at <NUM> using a Brookfield LVF Viscometer. Of the total solids content of the dispersion, <NUM> weight% comes from the mono-dicarbinol terminated polydimethylsiloxane.

Under a nitrogen atmosphere a mixture <NUM> of a polycarbonate diol, derived from hexanediol, with a molecular weight of <NUM>, <NUM> of dipropylene glycol dimethyl ether, <NUM> of X-<NUM>-176F (a mono-dicarbinol terminated polydimethylsiloxane from Shin-Etsu Chemical Company; molecular weight <NUM> Dalton) and <NUM> of dimethylolpropanoic acid were heated to <NUM> while stirring. <NUM> of <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclo-hexylisocyanate together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst were added and the mixture was heated to <NUM> and stirred for <NUM> hours to form a polyurethane prepolymer. The reaction was cooled down and the amount of remaining NCO was measured. A mixture was made of <NUM> of the prepolymer and <NUM> of triethylamine, and this mixture was dispersed into a water phase consisting of <NUM> of water, <NUM> of Provichem 2588P (a <NUM>% solution of sodium dioctyl sulfosuccinate in dipropylene glycol dimethyl ether, from Proviron Functional Chemicals NV) and <NUM> of hydrazine hydrate. The dispersion was stirred for an additional <NUM> minutes. The solids content of the dispersion was <NUM>%. The dispersion was filtered over <NUM> filter. The viscosity of the dispersion was <NUM> mPa. s, as measured at <NUM> using a Brookfield LVF Viscometer. Of the total solids content of the dispersion, <NUM> weight% comes from the mono-dicarbinol terminated polydimethylsiloxane.

Under a nitrogen atmosphere a mixture of <NUM> of <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclohexylisocyanate and <NUM> of X-<NUM>-176DX (a mono-dicarbinol terminated polydimethylsiloxane from Shin-Etsu Chemical Company; molecular weight <NUM> Dalton) together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst were reacted with each other for one hour at <NUM>. The reaction was cooled down and the amount of remaining NCO was measured.

Under a nitrogen atmosphere a mixture <NUM> of a polycarbonate diol, derived from hexanediol, with a molecular weight of <NUM>, <NUM> of dipropylene glycol dimethyl ether and <NUM> of dimethylolpropanoic acid were heated to <NUM> while stirring. <NUM> of <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclo-hexylisocyanate and <NUM> of the reaction product of the afore-mentioned <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclo-hexylisocyanate and X-<NUM>-176DX, together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst, were added and the mixture was heated to <NUM> and stirred for <NUM> hours to form a polyurethane prepolymer. The reaction was cooled down and the amount of remaining NCO was measured. A mixture was made of <NUM> of the prepolymer and <NUM> of triethylamine, and this mixture was dispersed into a water phase consisting of <NUM> of water, <NUM> of Provichem 2588P (a <NUM>% solution of sodium dioctyl sulfosuccinate in dipropylene glycol dimethyl ether, from Proviron Functional Chemicals NV) and <NUM> of hydrazine hydrate. The dispersion was stirred for an additional <NUM> minutes. The solids content of the dispersion was <NUM>%. The viscosity of the dispersion was <NUM> mPa. s, as measured at <NUM> using a Brookfield LVF Viscometer. Of the total solids content of the dispersion, <NUM> weight% comes from the mono-dicarbinol terminated polydimethylsiloxane.

Under a nitrogen atmosphere <NUM> of a polycarbonate diol, derived from hexanediol, with a molecular weight of <NUM>, <NUM> of dipropylene glycol dimethyl ether and <NUM> of dimethylolpropanoic acid were heated to <NUM> while stirring. <NUM> of dicyclohexyl-methane-<NUM>,<NUM>'-diisocyanate together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst was added and the mixture was heated to <NUM> and stirred for <NUM> hours to form a polyurethane prepolymer. The reaction was cooled down and the amount of remaining NCO was measured. A mixture was made of <NUM> of the prepolymer and <NUM> of triethylamine, and this mixture was dispersed into a water phase consisting of <NUM> of water, <NUM> of Aerosol OT-<NUM> (from Cytec Industries) and <NUM> of hydrazine hydrate. The dispersion was stirred for an additional <NUM> minutes. The solids content of the dispersion was <NUM>%. The viscosity of the dispersion was <NUM> mPa. s, as measured at <NUM> using a Brookfield LVF Viscometer.

Under a nitrogen atmosphere a mixture of <NUM> of <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclohexylisocyanate and <NUM> of Fluid OH <NUM> D (a linear dicarbinol terminated polydimethylsiloxane from Wacker Chemie AG; molecular weight <NUM> Dalton) together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst were reacted with each other for one hour at <NUM>. The reaction was cooled down and the amount of remaining NCO was measured.

Under a nitrogen atmosphere <NUM> of a polycarbonate diol, derived from hexanediol, with a molecular weight of <NUM>, <NUM> of dipropylene glycol dimethyl ether and <NUM> of dimethylolpropanoic acid were heated to <NUM> while stirring. <NUM> of dicyclohexyl-methane-<NUM>,<NUM>'-diisocyanate and <NUM> of the reaction product of the afore-mentioned <NUM>-isocyanatomethyl-<NUM>,<NUM>,<NUM>-trimethylcyclo-hexylisocyanate and Fluid OH <NUM> D,together with <NUM> of K-Kat <NUM> (from King Industries) as catalyst was added and the mixture was heated to <NUM> and stirred for <NUM> hours to form a polyurethane prepolymer. The reaction was cooled down and the amount of remaining NCO was measured. A mixture was made of <NUM> of the prepolymer and <NUM> of triethylamine, and this mixture was dispersed into a water phase consisting of <NUM> of water, <NUM> of Provichem 2588P (a <NUM>% solution of sodium dioctyl sulfosuccinate in dipropylene glycol dimethyl ether, from Proviron Functional Chemicals NV) and <NUM> of hydrazine hydrate. The dispersion was stirred for an additional <NUM> minutes. The solids content of the dispersion was <NUM>%. The viscosity of the dispersion was <NUM> mPa. s, as measured at <NUM> using a Brookfield LVF Viscometer. Of the total solids content of the dispersion, <NUM> weight% comes from the linear dicarbinol terminated polydimethylsiloxane.

Anti-soiling tests were performed on films made on release paper, on a Martin-Dale apparatus following ISO <NUM>-<NUM>:<NUM> method, with soiling cloth according to ISO <NUM>-<NUM> size, using Daimler-<NUM> cloth and <NUM> cycles. The degree of soiling was determined by measuring the coloration by a colour computer. Coloration is expressed in ΔE values, where a higher value indicates more darkening, with a lower value being best, and in Grayscale, where the scale is from <NUM> to <NUM>, with <NUM> being best.

Taber Abrasion resistance was tested on films made on vinyl as substrate, following ISO <NUM>-<NUM>:<NUM> method, using H18 wheel, <NUM> load and <NUM> cycles. The extent of abrasion was measured by weight loss, where a lower weight loss is best.

Water repellence was measured according to AATCC TM <NUM>, which determines resistance to wetting by aqueous liquids. Drops of water-alcohol mixtures of varying surface tensions were placed on the surface of a dried film on release, and the extent of surface wetting was determined visually on a scale from <NUM> to <NUM>, with <NUM> indicating the highest water repellence.

The comparative example <NUM> gave a strong coloration after the soiling test, as is demonstrated by the large ΔE value and low value in the grey-scale. The inventive examples <NUM> to <NUM> gave a much lower ΔE value and much higher value in the grey-scale. This demonstrates that the anti-soiling is much improved by the incorporation of mono-dicarbinol terminated polydimethylsiloxane into the polyurethane of the aqueous polyurethane dispersion.

The Taber abrasion of the inventive examples <NUM> to <NUM> was only little higher than of the comparative example <NUM>, demonstrating that the abrasion is almost not altered by the incorporation of mono-dicarbinol terminated polydimethylsiloxane into the polyurethane of the aqueous polyurethane dispersion.

The water repellence test results demonstrate that the water repellence is increased compared to comparative example <NUM>, by the incorporation of mono-dicarbinol terminated polydimethylsiloxane into the polyurethane of the aqueous polyurethane dispersion.

Claim 1:
A process for the preparation of an aqueous polydialkylsiloxane-polyurethane dispersion wherein the polydialkylsiloxane is present as a side chain of the polyurethane resin, comprising the steps of:
i) synthesizing a polyurethane prepolymer from isocyanates, polyols, that include polyols with hydrophilic groups and/or polyols that have an additional functional group that is capable of forming a salt, and a polydialkylsiloxane component A, said component A having <NUM> hydroxyl groups attached to an alkyl group on one end of the linear polydialkylsiloxane chain and an alkyl group on the other end of the linear polydialkylsiloxane chain; and
ii) dispersing the obtained prepolymer into a water phase optionally comprising other additives,
(iii) adding one or more neutralizing agents prior to, simultaneously with or after dispersing the prepolymer in water,
(iv) forming polyurethane by reacting with one or more extension agents simultaneously with or subsequent to the dispersing, after which optionally other additives may be added.