Lubricant-filled polyurea microcapsules

Abstract

A microcapsule comprising a core and a shell enclosing said core, the core comprising a lubricant and the shell comprising a polyurea.

Description

[0001] Lubricant-filled polyurea microcapsules

[0002] Technical field of the invention

[0003] The present invention relates to lubricant-filled microcapsules, their preparation and their use in compositions suitable for extrusion, casting or coating of articles.

[0004] Background of the invention

[0005] Certain applications, such as mechanical engineering, require dry lubrication of components. Previously, such components were coated with fluorine-containing polymers, such as polytetrafluoroethylene (PTFE). This can significantly reduce the coefficient of friction between two metal components.

[0006] However, PTFE belongs to the group of per- and polyfluorinated chemicals (PFAs), which are harmful to health and, especially with regard to their longevity, also pose environmental problems.

[0007] Therefore, the state of the art was looking for alternative dry lubricants which can be applied, for example, as a coating on metal components and which do not contain PFAs.

[0008] For this purpose, the state of the art describes microcapsules filled with lubricating oil, which can be used in thermoplastic composites, wet coatings, powder coatings and rubbers under conventional processing conditions.

[0009] The prior art describes the production of polyurethane-based microcapsules filled with a lubricating oil containing PFAs. However, these polyurethane-based microcapsules have the disadvantage that they contain PFAs and their thermal and, in particular, chemical stability is insufficient to ensure stability in a water-based formulation (M. Grünewald, “Tribological and mechanical properties of lubricant-filled microcapsules in thermoplastic composites," innoTRAC, Vol. 2, No. 1, pp. 25-44). This is confirmed by the fact that the prior art has shown that hydrolytic degradation of polyurethane already occurs within the first few weeks at elevated temperatures, with the addition of fatty acids (often used as additives in the products) significantly accelerating this process (C.S. Schollenberg, F.D. Stewart, “Thermoplastic Polyurethane Hydrolysis Stability,” Die Angewandte Makromolekulare Chemie 29 / 30, pp.413-130, No. 421). The production of these mostly polymer-based composite products often requires the use of high temperatures, mechanical and chemical forces, and combinations thereof. For example, elastomers are processed by extrusion, injection molding, and 3D printing, whereby high temperatures, shear forces, and / or high pressure act on the material simultaneously. When processing resins, rubbers, stoving and powder coatings, shear forces are also applied during homogenization and high temperatures during curing to ensure the required product quality. Wet coating formulations are often acidic or basic and / or contain organic solvents, which create a chemically active environment. Furthermore, polymer products often contain additives that can release reactive components or have a chemically reactive effect during the process.

[0010] To achieve this, the microcapsules must demonstrate stability at processing temperatures above 100 °C, at pH values ​​between 2 and 12, and under mechanical stress (e.g., extruders or stirrers), and combinations thereof. Furthermore, it is necessary that the microcapsule core remains available for release throughout the entire service life of the product, which can be between 1 and 20 years, and that there is no risk of it spontaneously crosslinking or otherwise inactivating over time. Furthermore, it is necessary to use only the most sustainable materials possible, and, above all, to avoid chemicals that are particularly persistent or toxic (such as PFAs).

[0011] The occurrence of mechanical, chemical, and thermal stresses during further processing often leads to the microcapsules described in the prior art being damaged during processing, thus releasing their contents before their actual use. During the manufacture of components from composite materials containing the microcapsules of the prior art, this leads to the separation of the capsule core material and the composite material, resulting in the appearance of liquid lubricating oil on the surface immediately after the parts have been manufactured. Furthermore, this effect leads to a significant deterioration in the mechanical properties of these articles. In coatings with a material containing microcapsules described in the prior art, premature release of lubricating oil can also lead to insufficient adhesion between the coating and the surface to be coated.

[0012] For example, CN 108003970 A describes the production of melamine resin capsules containing a liquid lubricating oil and their use in mechanical engineering, aircraft construction, and shipbuilding. However, these microcapsules have the disadvantage described above: their thermal, mechanical, and chemical resistance is not always sufficient.

[0013] Summary of the invention

[0014] The state of the art therefore shows microcapsules filled with lubricating oil, which do not have sufficient mechanical and chemical stability.

[0015] It is therefore the object of the present invention to provide microcapsules which can also be incorporated into materials which require high shear forces, high temperatures or demanding chemical environments during production.

[0016] It has now surprisingly been found that this object is achieved by a microcapsule which comprises a core and a shell enclosing the core, wherein the core comprises a lubricant and wherein the shell comprises a polyurea.

[0017] Furthermore, it was surprisingly found that the above-mentioned object is achieved by a method for producing a microcapsule, the method comprising the following steps:

[0018] A) Mixing an isocyanate having at least two isocyanate groups with a lubricant, thereby producing mixture A,

[0019] B) preparing an at least two-phase emulsion, wherein a first phase of the emulsion comprises the mixture A and a second phase of the emulsion comprises a crosslinking agent,

[0020] C) Crosslinking the isocyanate with the crosslinking agent to form a polyurea.

[0021] Furthermore, it has surprisingly been found that the above-mentioned object is achieved by the use of a microcapsule according to the present invention as a lubricant in a composition, preferably in a coating composition or in an extruded article.

[0022] Furthermore, it has surprisingly been found that the above-mentioned object is achieved by the use of a microcapsule according to the present invention in an extrusion process or a coating process, preferably in a plasma coating process.

[0023] In addition, it has surprisingly been found that the above-mentioned object is achieved by a composition for casting, coating or extruding articles, which composition comprises a microcapsule according to the present invention.

[0024] To this end, it has surprisingly been found that the above-mentioned object is achieved by using the composition for casting, coating or extruding according to the present invention for reducing friction between articles.

[0025] Finally, it was surprisingly found that the above-mentioned object is achieved by an article comprising the microcapsule or the composition according to the present invention.

[0026] The advantage of the microcapsule of the present invention is that the polyurea contained in the supporting structure of the microcapsule, i.e., the shell, allows for significantly more resilient supporting structures. These supporting structures made of polyurea therefore withstand mechanical stresses such as shear forces better than known supporting structures in lubricating oil-filled microcapsules. The same applies to temperature and chemical resistance.

[0027] The present invention thus describes lubricating oil-filled microcapsules that are suitable as a universally applicable additive in the production of a wide range of products with low friction coefficients. The microcapsules are particularly suitable for use in thermoplastic composites, wet coatings, powder coatings, plasma coatings, and rubbers.

[0028] Short description of the figures

[0029] Figure 1 is a photograph of microcapsule suspensions after one week of treatment from examples IE1 (1 = pH 2, 2 = pH 13), CE2 (3 = pH 2, 4 = pH 13) and CE1 (5 = pH 2, 6 = pH 13)

[0030] Figure 2 is a light micrograph of a suspension of the microcapsules as prepared in IE7

[0031] Figure 3 is a light micrograph of a suspension of the microcapsules as prepared in IE8

[0032] Figure 4 is a light micrograph of a suspension of the microcapsules as prepared in IE9

[0033] Figure 5 is a light micrograph of a suspension of the microcapsules as prepared in CE3 Figure 6 is a light micrograph of a suspension of the microcapsules as prepared in CE4

[0034] Definitions

[0035] The term "lubricant" as used herein refers to a substance that serves to reduce friction between two surfaces. Other properties of lubricants include reducing surface wear, cooling components, vibration dampening, sealing, and corrosion protection. Lubricants are typically mixtures and contain at least one lubricating grease, lubricating oil, or lubricating wax. Lubricants may contain additional additives. However, lubricants can also consist of only one lubricating grease, lubricating oil, or lubricating wax.

[0036] The term "lubricating oil" as used herein refers to a component of a lubricant. Lubricating oils are typically liquid under normal conditions.

[0037] A hardening lubricating oil is a lubricating oil that becomes highly viscous and, in the worst case, solidifies due to aging processes such as exposure to UV light and / or oxygen. Typically, exposure to UV light and / or oxygen causes cross-linking of the polymer chains in a lubricating oil. Generally, lubricating oils with an iodine number below 140, measured according to ASTM D1541, are not hardening lubricating oils.

[0038] The term "grease" as used herein refers to a component of a lubricant. Typically, lubricating greases are solid under normal conditions. Typically, a lubricating wax is not malleable under normal conditions.

[0039] The term "lubricating wax" as used herein refers to a component of a lubricant. Lubricating waxes are typically solid under normal conditions. Typically, a lubricating wax is malleable under normal conditions.

[0040] Detailed description of the invention

[0041] The present invention relates to a microcapsule, a manufacturing process for this microcapsule, a composition comprising this microcapsule, uses of the microcapsule and the composition, and an article comprising the microcapsule or the composition.

[0042] As described above, the present invention relates to a microcapsule comprising a core and a shell surrounding the core, wherein the core comprises a lubricant and wherein the shell comprises a polyurea.

[0043] The lubricant can be a single substance or a mixture of substances. The lubricant is released during use of the microcapsule. Mechanical stress damages the microcapsule shell, allowing the lubricant to escape and penetrate between component surfaces, ideally at the point of mechanical stress, where it reduces friction between these surfaces.

[0044] The lubricant can be in a liquid or solid state. However, the lubricant is preferably liquid, at least under the application conditions, i.e., within certain pressure or temperature ranges. This has the advantage that it can be distributed more quickly between the surfaces to be lubricated and also exhibits better lubricating properties during application. However, the lubricant can be solid in the microcapsule before or during application, e.g., in the form of a wax.

[0045] Preferably, the lubricant of the microcapsule of the present invention is liquid under use conditions. More preferably, the lubricant of the microcapsule of the present invention is liquid under normal conditions. Most preferably, the lubricant of the microcapsule of the present invention is liquid under both normal conditions and use conditions.

[0046] Likewise, the lubricant of the microcapsule of the present invention preferably comprises one or more lubricating greases, one or more lubricating oils, one or more lubricating waxes, or mixtures thereof. More preferably, the lubricant of the microcapsule of the present invention comprises one or more lubricating greases, one or more lubricating oils, or mixtures thereof. Even more preferably, the lubricant of the microcapsule of the present invention comprises one or more lubricating oils, or mixtures thereof. The lubricant of the microcapsule of the present invention may further comprise additives.

[0047] The lubricant of the present invention preferably does not comprise any polyfluorinated chemicals (PFAs). More preferably, the lubricant of the microcapsule of the present invention consists of one or more lubricating greases, one or more lubricating oils, one or more lubricating waxes, or mixtures thereof, and optionally one or more additives. More preferably, the lubricant of the microcapsule of the present invention consists of one or more lubricating greases, one or more lubricating oils, or mixtures thereof, and optionally one or more additives. More preferably, the lubricant of the microcapsule of the present invention consists of one or more lubricating oils, or mixtures thereof, and optionally one or more additives.

[0048] In a preferred embodiment of the invention, the lubricating oil is selected from the group consisting of a mineral oil, a synthetic oil and a vegetable oil.

[0049] Preferably, the synthetic oil of the microcapsule of the present invention is selected from the group consisting of an alkylated naphthalene, an ester oil, a multialkylated cyclopentane, a polyolefin, a polyphenyl ether, a polyglycol oil, a silicone oil, a polybutene, a polyol ester, a polyalkylene glycol, a phosphate ester, an alkane or paraffin, an alkene or olefin, a naphthene, a fluoride-free ionic liquid, and mixtures thereof. More preferably, the synthetic oil is selected from the group consisting of an ester oil, a polyolefin, a polyol ester, a phosphate ester, an alkene or olefin, and mixtures thereof.

[0050] Also preferably, the vegetable lubricating oil of the microcapsule of the present invention is selected from the group consisting of linseed oil, soybean oil, sunflower oil, olive oil, safflower oil, rapeseed oil, tung oil, oiticica oil, castor oil, tall oil, palm oil, palm kernel oil, peanut oil, corn germ oil, coconut oil, sesame oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, castor oil, wheat germ oil, hemp oil, poppy seed oil, grape seed oil, walnut oil, rosehip oil, blackcurrant seed oil, kukui nut oil, perilla oil, isano oil, stillingia oil, lallemantia oil and cottonseed oil.

[0051] More preferably, the vegetable lubricating oil of the microcapsule of the present invention is selected from the group consisting of soybean oil, sunflower oil, olive oil, safflower oil, rapeseed oil, castor oil, tall oil, palm oil, palm kernel oil, peanut oil, corn germ oil, coconut oil, sesame oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, wheat germ oil, hemp oil, poppy seed oil, grape seed oil, walnut oil, rosehip oil, blackcurrant seed oil, kukui nut oil, and cottonseed oil.

[0052] Even more preferably, the vegetable lubricating oil of the microcapsule of the present invention is selected from the group consisting of sunflower oil, olive oil, rapeseed oil, castor oil, tall oil, palm oil, palm kernel oil, corn oil, coconut oil, sesame oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, wheat germ oil, and cottonseed oil.

[0053] Still preferably, the vegetable lubricating oil of the microcapsule of the present invention is selected from the group consisting of olive oil, castor oil, tall oil, palm oil, palm kernel oil, coconut oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, wheat germ oil, and cottonseed oil.

[0054] Most preferably, the vegetable lubricating oil of the microcapsules of the present invention is selected from the group consisting of olive oil, castor oil, tall oil, palm oil, palm kernel oil, coconut oil, babassu oil, avocado oil, jojoba oil, and almond oil.

[0055] Preferably, the lubricating oil, more preferably the vegetable lubricating oil, of the microcapsules of the present invention is a non-hardening lubricating oil. More preferably, the non-hardening lubricating oil, preferably a non-hardening vegetable lubricating oil, of the microcapsules of the present invention has an iodine value of less than 140, more preferably less than 100, as measured according to ASTM D1541.

[0056] Hardening lubricating oils have the property of cross-linking over time, e.g., due to oxidation, but also due to UV light. This creates the risk that the core material will become more viscous or even harden after a certain storage period. Consequently, the lubricating oil can no longer escape from the shell during use, or only at a slower rate. Furthermore, the lubricating properties of the lubricating oil are reduced by cross-linking or are no longer suitable for the application window. As a result, the tribological functionality of the microcapsules is lost over time. It has now been shown that this disadvantage can be remedied by using non-hardening lubricating oils, preferably non-hardening vegetable lubricating oils.

[0057] As described above, the microcapsule material of the shell of the microcapsule of the present invention comprises polyurea. Preferably, the shell consists of polyurea and optional additives. This enables optimal resistance of the microcapsules to mechanical and chemical influences.

[0058] The polyurea of ​​the shell of the microcapsule of the present invention preferably comprises a polymer having a structural unit according to formula (I): Formula (I) Preferably, the polyurea of ​​the shell is prepared by the polymerization process according to the present invention as described below.

[0059] The polyurea of ​​the microcapsule shell according to formula (I), wherein RR' is an aliphatic, cycloaliphatic, or aromatic hydrocarbon radical. Preferably, the hydrocarbon radical is free of heteroatoms. Preferably, at least R or R' is a cycloaliphatic or aromatic hydrocarbon radical. More preferably, R and R' are a cycloaliphatic or aromatic hydrocarbon radical.

[0060] A cycloaliphatic hydrocarbon residue defines a residue that contains at least one cycloaliphatic ring. In parallel, an aromatic hydrocarbon residue defines a residue that contains at least one aromatic ring.

[0061] Typically, R and / or R' in both the aromatic and cycloaliphatic hydrocarbon residues contain more structures than just one aromatic or cycloaliphatic ring.

[0062] It has been shown that such a polyurea further minimizes agglomeration of the microcapsules in a suspension, thus enabling more homogeneous suspensions. This results in better structural integrity of the articles manufactured from it and more uniform lubricant release during operation.

[0063] Preferably, the aromatic hydrocarbon radicals are selected from the group consisting of diphenylmethyl, biphenyl, 3,3'-dimethyl-1,1'-biphenyl, phenyl, toluyl, xylylenyl, and naphthyl, where these radicals may be substituted, preferably with substituents selected from the group consisting of H, F, Cl, Br, Ci-4-alkyl and Ci-4-alkoxy.

[0064] In general, the cycloaliphatic hydrocarbon radicals include all aromatic hydrocarbon radicals in fully hydrogenated form. The cycloaliphatic hydrocarbon radicals are preferably selected from the group consisting of cyclohexyl, dicyclohexylmethyl, and isophoryl, where these radicals may be substituted, preferably with substituents selected from the group consisting of H, F, Cl, Br, C1-4-alkyl, and C1-4-alkoxy.

[0065] Preferably, the microcapsule of the present invention consists of 80 to 100 wt.%, more preferably 85 to 100 wt.%, even more preferably 90 to 100 wt.%, especially 95 to 100 wt.%, especially 97.5 to 100 wt.%, of the combined amounts of the lubricant and the microcapsule material, wherein the wt.% is based on the total weight of the microcapsules of the present invention.

[0066] Preferably, the microcapsule of the present invention consists of 10 to 95 wt.%, more preferably 30 to 90 wt.%, even more preferably 50 to 85 wt.%, particularly preferably 70 to 80 wt.% lubricant, wherein the wt.% is based on the total weight of the microcapsules of the present invention.

[0067] Preferably, the microcapsule of the present invention consists of 5 to 90 wt.%, more preferably 5 to 80 wt.%, even more preferably 5 to 60 wt.%, even more preferably 5 to 40 wt.%, even more preferably 10 to 30 wt.% microcapsule material, wherein the wt.% relates to the total weight of the microcapsules of the present invention.

[0068] Preferably, the weight ratio (w / w) of lubricant to microcapsule material in the microcapsules of the present invention is from 1:1 to 10:1, more preferably from 1:1 to 7:1, even more preferably from 1:1 to 5:1.

[0069] Preferably, the microcapsule of the present invention has a volume-average particle size of 0.3 to 800 pm, more preferably 0.3 to 100 pm, and most preferably 5 to 50 pm.

[0070] Preferably, the microcapsule of the present invention has a D10 value in the range of 0.2 to 10 pm, more preferably in the range of 0.2 to 5 pm.

[0071] Preferably, the microcapsule of the present invention has a D50 value in the range of 0.5 to 80 pm, preferably in the range of 10 to 50 pm, more preferably 20 to 30 pm.

[0072] Preferably, the microcapsule of the present invention has a D90 value in the range of 5 to 100 pm, preferably in the range of 6 to 35 pm, and most preferably in the range of 5 to 80 pm.

[0073] In addition to the lubricant and microcapsule material of the shell, the microcapsules of the present invention may contain one or more additives that may be present in the production of the microcapsules of the present invention.

[0074] The additive is preferably selected from the group consisting of gum arabic, polyalcohol, polyacrylate, unsaponified or partially saponified polyvinyl acetate, polyvinylpyrrolidone, cellulose ether, starch, proteins, alginate, pectin, gelatin, polysaccharide, sodium or magnesium silicate, carboxymethylcellulose, acrylate and acrylic polymer, acrylate-aminoacrylate copolymer, arabinogalactan, carrageenan, water-swellable clay, maltodextrin, natural gum, protein hydrolysate and its quaternized form, poly(vinylpyrrolidone-co-vinyl acetate), poly(vinyl alcohol-co-vinyl acetate), poly(maleic acid), maleic acid-vinyl copolymer, poly(alkylene oxide), poly(vinyl methyl ether), poly(vinyl ether-co-maleic anhydride), poly(ethyleneimine), poly((meth)acrylamide), poly(alkylene oxide-co-dimethylsiloxane), poly(aminodimethylsiloxane), sodium lignosulfonate, Maleic anhydride / styrene copolymer, ethylene / maleic anhydride copolymer, copolymer of ethylene oxide, propylene oxide and ethylenediamine,Fatty acid esters of polyethoxylated sorbitol and sodium dodecyl sulfate with polyalcohol.

[0075] The natural gum is preferably selected from the group consisting of xanthan gum, gellan gum, guar gum, and alginate esters. Polyacrylate can be an acrylic copolymer potassium salt. Cellulose ether is preferably selected from the group consisting of tylose, methylcellulose, hydroxyethylcellulose, or hydroxypropylmethylcellulose.

[0076] The additive is preferably selected from the group consisting of gum arabic, polyalcohol and polyacrylate, unsaponified or partially saponified polyvinyl acetate, polyvinylpyrrolidone, cellulose ether, starch, alginate, pectin, gelatin, polysaccharide, xanthan gum, sodium or magnesium silicate, carboxymethylcellulose and polyacrylic acids.

[0077] Most preferably, the additive is selected from the group consisting of gum arabic, polyalcohol, polyacrylate and polyvinylpyrrolidone.

[0078] Therefore, the microcapsules of the present invention may comprise part or all of the amount of additive used in the preparation of the microcapsules of the present invention, preferably the microcapsules of the present invention may comprise up to 10 wt%, more preferably up to 7.5 wt%, even more preferably up to 6 wt%, especially up to 5 wt%, of additive, wherein the wt% is based on the amount of polyurea of ​​the microcapsule of the present invention.

[0079] Preferably, the microcapsules of the present invention may comprise between 0.001 and 10 wt.%, preferably between 0.01 and 7.5 wt.%, more preferably from 0.01 to 6 wt.%, especially from 0.01 to 5 wt.%, of additive, wherein the wt.% relates to the amount of polyurea in the microcapsule of the present invention. Each of these values ​​is also an indication of the possible amounts of additive that may be included in the manufacturing process of the present invention. The microcapsules of the present invention may comprise part or all of the amount of catalyst used in the manufacture of the microcapsules of the present invention. Therefore, the microcapsules of the present invention may comprise up to 10 wt.%, preferably up to 7.5 wt.%, more preferably up to 5 wt.% of catalyst, wherein the wt.% relates to the amount of polyurea in the microcapsule of the present invention.Preferably, the microcapsules of the present invention may therefore comprise between 0.001 and 10 wt%, preferably between 0.001 and 7.5 wt%, more preferably 0.001 to 5 wt%, of the catalyst, the wt% being based on the amount of polyurea of ​​the microcapsule of the present invention.

[0080] The catalyst can be selected from the group consisting of DABCO, dimethylcyclohexylamine, dimethylethanolamine, triethylenediamine, N,N,N',N",N"-pentamethyldiethylenetriamine, 1,2-dimethylimidazole, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N',N'-trimethylaminoethylpiperazine, 1,1'-[[3-(dimethylamino)propyl]imino]bispropan-2-ol, N,N,N'-trimethylaminoethylethanolamine and N,N',N"-tris(3-dimethylaminopropyl)-hexahydro-s-triazine.

[0081] The catalyst is preferably DABCO or triethylenediamine.

[0082] Preferably the catalyst is DABCO.

[0083] Preferably, the microcapsules of the present invention are substantially free of solvent.

[0084] Preferably, the microcapsules of the present invention do not contain a solvent.

[0085] As described above, the manufacturing method of the present invention relates to a method for producing a microcapsule, the method comprising the following steps

[0086] A) Mixing an isocyanate having at least two isocyanate groups with a lubricant, thereby producing mixture A,

[0087] B) preparing an at least two-phase emulsion, wherein a first phase of the emulsion comprises the mixture A and a second phase comprises a crosslinking agent,

[0088] C) Crosslinking the isocyanate with the crosslinking agent to form a polyurea. Step A): Mixing the isocyanate with at least two isocyanate groups with a lubricant

[0089] In step A), the isocyanate with at least two isocyanate groups is initially introduced and mixed with the lubricant. The resulting mixture can be a mixture with or without solvent. Mixture A) can comprise only one isocyanate with at least two isocyanate groups, but can also comprise a mixture of two or more isocyanates with at least two isocyanate groups.

[0090] Preferably, the isocyanate having at least two isocyanate groups is selected from the group consisting of isocyanate monomers, isocyanate trimers, biuret isocyanates, isocyanurates, polymeric isocyanates and mixtures thereof.

[0091] Preferably, the isocyanate monomers are selected from the group consisting of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethyl diisocyanate (HDI) and mixtures thereof, more preferably from the group consisting of toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI) and mixtures thereof.

[0092] Preferably, the isocyanate dimers are selected from the group consisting of toluene diisocyanate dimer (TDI dimer), diphenylmethane diisocyanate dimer (MDI dimer) and mixtures thereof.

[0093] Preferably, the isocyanate trimers are selected from the group consisting of hexamethyl diisocyanate trimer (HDI trimer), isophorone diisocyanate trimer (IPDI trimer) and mixtures thereof, more preferably isophorone diisocyanate trimer (IPDI trimer).

[0094] The polymeric isocyanates preferably comprise polymeric diphenylmethane diisocyanate (PMDI), preferably they consist thereof.

[0095] The isocyanate with at least two isocyanate groups contains two, preferably more than two, isocyanate groups per molecule.

[0096] Preferably, the isocyanate having at least two isocyanate groups is a compound of formula (II) or an isocyanate prepolymer;

[0097] 114

[0098] (H) wherein n4 is an integer greater than or equal to 2, preferably from 2 to 502, more preferably from 2 to 202, even more preferably from 2 to 102, especially preferably from 2 to 52, even more especially preferably from 2 to 27, especially preferably from 2 to 22, even more especially preferably from 2 to 17, most preferably from 2 to 12;

[0099] R30 is a group which links the two or more isocyanate groups together, including any aromatic, aliphatic or cycloaliphatic groups or combinations of any aromatic, aliphatic or cycloaliphatic groups capable of linking the isocyanate groups together, preferably any aromatic or cycloaliphatic groups or combinations of any aromatic or cycloaliphatic groups.

[0100] The isocyanate prepolymer is an isocyanate formed by a reaction between a compound of formula (II) and a protic compound selected from the group consisting of polyalcohol, water, polyamine, and mixtures, wherein in this reaction, this compound is present in substoichiometric amounts relative to the isocyanate containing at least two isocyanate groups. The ratio of OH groups of the polyalcohol to isocyanate groups of the isocyanate is preferably no greater than 1:2, preferably no greater than 1:3, more preferably no greater than 1:5, and most preferably no greater than 1:10.

[0101] The isocyanate having at least two isocyanate groups is preferably selected from the group consisting of aliphatic diisocyanates, cycloaliphatic diisocyanates, and aromatic diisocyanates, where n4 in formula (II) is 2. More preferably, it is selected from the group consisting of cycloaliphatic diisocyanates and aromatic diisocyanates, where n4 in formula (II) is 2. Diisocyanates containing an aliphatic segment and / or a cycloaliphatic ring segment or an aromatic ring segment can also be used in the context of the present invention, but preference is given to diisocyanates containing a cycloaliphatic ring segment or an aromatic ring segment.

[0102] A preferred aliphatic diisocyanate is the aliphatic diisocyanate of the compound according to formula (III): where n5 is an integer having an average value of about 2 to about 18, preferably from about 3 to about 17, more preferably from about 4 to about 15, most preferably from about 4 to 13. Average means that the compound of formula (III) is a mixture of the respective compounds and n5 is represented as an average (or mean) value.

[0103] Preferably, n5 is an integer from 2 to 18, more preferably from 4 to 16, even more preferably from 6 to 14, in particular from 6 to 10, most preferably n5 is 6 or 9.

[0104] Preferably, n5 is 6, meaning that formula (III) describes 1,6-hexamethylene diisocyanate. The molecular weight of 1,6-hexamethylene diisocyanate is approximately 168.2 g / mol. Since 1,6-hexamethylene diisocyanate contains two isocyanate groups per molecule, its equivalent weight is approximately 84.1 g / mol.

[0105] The equivalent weight of a polyisocyanate is generally defined as the molecular weight divided by the number of isocyanate groups per molecule. As mentioned above, for some polyisocyanates, the actual equivalent weight may differ from the theoretical equivalent weight, some of which are listed here.

[0106] In certain preferred embodiments, the aliphatic diisocyanates comprise dimers of diisocyanates, preferably a compound of formula (IV): where n5 is defined as above.

[0107] Preferably, n5 in formula (IV) is 6, ie the compound of formula (IV) is a dimer of 1,6-hexamethylene diisocyanate (molecular weight of about 339.39 g / mol;

[0108] equivalent weight of about 183 g / mol).

[0109] Preferably, a wide range of cycloaliphatic and aromatic diisocyanates can also be used. In general, aromatic diisocyanates include those diisocyanates in which the R30 linking group contains an aromatic ring, and cycloaliphatic diisocyanates include those diisocyanates in which the R30 linking group contains a cycloaliphatic ring. Typically, the R30 linking group in both aromatic and cycloaliphatic diisocyanates contains more than just an aromatic or cycloaliphatic ring. Certain commercially available aromatic diisocyanates consist of two benzene rings, which may be linked directly or via an aliphatic linking group containing from 1 to about 4 carbon atoms. An example of such an aromatic diisocyanate is methylene di(phenyl isocyanate).

[0110] Methylenedi(phenyl isocyanate) is commonly abbreviated to MDI. MDI is selected from the group consisting of MDI-2-2, i.e., 2,2'-diphenylmethane diisocyanate (CAS 2536-05-2), a compound of formula (V); MDI-2-4, i.e., 2,4'-diphenylmethane diisocyanate (CAS No. 5873-54-1), a compound of formula (VI); MDI-4-4, i.e., 4,4'-diphenylmethane diisocyanate (CAS 101-68-8), a compound of formula (VII); and mixtures thereof;

[0111] MDI is preferably a mixture of two of the above-mentioned isomers or a mixture of all three of the above-mentioned isomers. MDI has a molecular weight of approximately 250.25 g / mol and an equivalent weight of approximately 125 g / mol.

[0112] Other aromatic diisocyanates in which the benzene rings are directly bonded to each other are diisocyanates with a biphenyl group, such as the compound of formula (VIII): where

[0113] R39, R40, R41, and R42 are the same or different and are independently selected from the group consisting of H, F, Cl, Br, C1-4 alkyl, and C1-4 alkoxy. Preferably, R39, R40, R41, and R42 are the same or different and are independently selected from the group consisting of H, methyl, and methoxy.

[0114] An embodiment of the compound of formula (VIII) is the compound of formula (IX): where R39 and R41 are as defined above.

[0115] Examples of compounds of formula (VIII) are 4,4'-diisocyanato-1,1'-biphenyl, 4,4'-diisocyanato-3,3'-dimethyl-1,1'-biphenyl (molecular weight about 264.09 g / mol;

[0116] Equivalent weight about 132 g / mol), ie the compound of formula (X): and dianisidine diisocyanate (4,4'-diisocyanato-3,3'-dimethoxybiphenyl) (molecular weight about 296 g / mol; equivalent weight about 148 g / mol), ie compound according to formula (XI):

[0117] Certain commercially available aromatic diisocyanates consist of a single benzene ring. The isocyanate groups can be bonded directly to the benzene ring or linked via aliphatic groups containing 1 to about 4 carbon atoms. An example of such an aromatic diisocyanate with a single benzene ring is the compound of formula (XII); where n19 and n20 are the same or different and independently represent 0, 1, 2, 3 or

[0118] 4 are;

[0119] R31, R32, R33, and R34 are the same or different and are independently selected from the group consisting of H, F, Cl, Br, C1-4 alkyl, and C1-4 alkoxy. Preferably, n19 and n20 are identical; even more preferably, n19 and n20 are 0.

[0120] Preferably R31, R32, R33 and R34 are H or methyl.

[0121] Aromatic diisocyanates with a single benzene ring are, for example, ortho-, meta- and para-phenylene diisocyanate (molecular weight about 160.1 g / mol; equivalent weight about 80 g / mol), ie the compound of formula (XIII), the compound of formula (XIV) and the compound of formula (XV):

[0122] Other aromatic diisocyanates with a single benzene ring are toluene diisocyanates. Toluene diisocyanates are commonly abbreviated TDI; preferred embodiments are 2,4-TDI with CAS 584-84-9 and 2,6-TDI with CAS 91-08-7 (both with a molecular weight of approximately 174.2 g / mol; equivalent weight of approximately 85 g / mol), and 2,4,6-triisopropyl-m-phenylene isocyanate.

[0123] Similar diisocyanates with aliphatic groups connecting the isocyanates to the benzene ring are 1,3-xylylene diisocyanate, 1,4-xylylene diisocyanate, tetramethyl-meta-xylylene diisocyanate, tetramethyl-para-xylylene diisocyanate and meta-tetramethylxylene diisocyanate (1,3-bis(2-isocyanatopropan-2-yl)benzene).

[0124] Other aromatic diisocyanates contain a naphthalene ring. An example of such an aromatic diisocyanate is 1,5-naphthylene diisocyanate.

[0125] Cycloaliphatic diisocyanate can have one or more cycloaliphatic rings with 4 to about 7 carbon atoms. Typically, a cycloaliphatic ring is a cyclohexane ring. The one or more cyclohexane rings can be linked directly or via an aliphatic linking group with 1 to 4 carbon atoms.

[0126] In addition, the isocyanate groups can be bonded directly to the cycloaliphatic ring or linked via an aliphatic group having 1 to about 4 carbon atoms.

[0127] Typical cycloaliphatic diisocyanates are aromatic diisocyanates that have been hydrogenated, such as hydrogenated methylenedi(phenyl isocyanate), i.e., hydrogenated MDI. Such hydrogenated MDI is commonly abbreviated as HMDI.

[0128] HMDI is selected from the group consisting of HMDI-2-2, ie the compound of formula (XVI), HMDI-2-4, ie the compound of formula (XVII), HMDI-4-4, ie the compound of formula (XVIII), and mixtures thereof:

[0129] (XVIII) Preferably, HMDI is a mixture of two of the mentioned isomers or a mixture of all three mentioned isomers. HMDI has a molecular weight of about 262 g / mol and an equivalent weight of about 131 g / mol. HMDI-4-4 is also known as 4,4'-diisocyanatodicyclohexylmethane, bis(4-isocyanatocyclohexyl)methane, or Desmodur (Covestro).

[0130] Other cycloaliphatic diisocyanates are aromatic diisocyanates with a single benzene ring that have been hydrogenated and therefore contain only one cyclohexane ring, such as the hydrogenated compound of formula (XII), represented by the compound of formula (XIX): where n19, n20, R31, R32, R33, and R34 are as defined above. Examples of such aromatic diisocyanates having a single benzene ring which have been hydrogenated and therefore contain only one cyclohexane ring are hydrogenated ortho-, meta-, and para-phenylene diisocyanates, i.e., compounds of formula (XX), compounds of formula (XXI), and compounds of formula (XXII).

[0131] Other aromatic diisocyanates with a single cyclohexane ring are hydrogenated toluene diisocyanates. Hydrogenated toluene diisocyanates are commonly abbreviated as HTDI; preferred embodiments are 2,4-HTDI and 2,6-HTDI, and 2,4,6-triisopropyl-m-cyclohexylene isocyanate.

[0132] Similar diisocyanates with aliphatic groups connecting the isocyanates to the cyclohexane ring are hydrogenated 1,3-xylylene diisocyanate, hydrogenated 1,4-xylylene diisocyanate, hydrogenated tetramethyl-meta-xylylene diisocyanate, hydrogenated tetramethyl-para-xylylene diisocyanate, and hydrogenated tetramethyl-meta-xylene diisocyanate (1,3-bis(2-isocyanatopropan-2-yl)benzene).

[0133] Examples of diisocyanates containing a single cyclohexane ring are 1,4-cyclohexylene diisocyanate and 1-methyl-2,4-diisocyanatocyclohexane. Other cycloaliphatic diisocyanates are 1,3-bis(isocyanatomethyl)cyclohexane and isophorone diisocyanate (also known as IPDI, 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, i.e., a compound of formula (XXIII)).

[0134] (XXIII)

[0135] Certain aliphatic triisocyanates include, for example, trifunctional

[0136] Adducts of linear aliphatic diisocyanates. The linear aliphatic diisocyanate can be a compound of formula (III), and the trifunctional adduct can then be a compound of formula (XXIV): with n5 as defined above.

[0137] A particularly preferred compound of formula (III) suitable for preparing aliphatic triisocyanates is hexamethylene 1,6-diisocyanate, and a particularly preferred aliphatic triisocyanate is a trimer of hexamethylene 1,6-diisocyanate. The aliphatic triisocyanates can be derived from the aliphatic isocyanate alone, i.e., dimers, trimers, etc., or they can arise from a reaction between the aliphatic isocyanate of structure (III) and a coupling reagent such as water or a low molecular weight triol such as trimethylolpropane, trimethylolethane, glycerol, or hexanetriol.

[0138] An exemplary aliphatic triisocyanate where n5 is 6 is the biuret-containing adduct (i.e., trimer) of hexamethylene-1,6-diisocyanate, compound of formula (XXV):

[0139] This material is commercially available under the trade names Desmodur N3200 (Covestro) or Tolonate HDB (Rhone-Poulenc). Desmodur N3200 has an approximate molecular weight of about 478.6 g / mol. The commercially available Desmodur N3200 has an approximate equivalent weight of about 191 g / mol (the theoretical equivalent weight is about 159 g / mol).

[0140] Another aliphatic triisocyanate derived from the aliphatic isocyanate of structure (III) is the compound of formula (XXVI); with n5 as defined above.

[0141] A specific compound of formula (XXVI) is a compound of formula (XXVII):

[0142] (XXVII) also known as HDI isocyanurate trimer, which is commercially available under the trade names Desmodur N3300 (Covestro) or Tolonate HDT (Rhone-Poulenc).

[0143] Desmodur N3300 has an approximate molecular weight of about 504.6 g / mol and an equivalent weight of about 168.2 g / mol.

[0144] Another exemplary aliphatic triisocyanate derived from an aliphatic isocyanate of structure (III) is a compound of formula (XXVIII):

[0145] (XXVIII) with n5 as defined above.

[0146] A specific compound of formula (XXVIII) is the triisocyanate adduct of

[0147] Trimethylolpropane and hexamethylene-1,6-diisocyanate, ie the compound of formula (XXIX):

[0148] The compound of formula (II) may also be a polymeric polyisocyanate. An example of such a polymeric polyisocyanate is polymeric

[0149] Methylene di(phenyl isocyanate), usually abbreviated PMDI, which can also be referred to as polymethylene polyphenyl isocyanate.

[0150] PMDI can be represented by the compound of formula (XXX). where

[0151] R43 and R44 are the same or different and are independently selected from the group consisting of H, C1-4-alkyl, C1-4-alkoxy, F, Cl, and Br; and n is an integer from 1 to 500. Preferably, R43 and R44 are the same or different and are independently selected from the group consisting of H and C1-4-alkyl.

[0152] More preferably, R43 and R44 are the same or different and independently selected from the group consisting of H and methyl; even more preferably, R43 and R44 are H.

[0153] Preferably, n is an integer from 1 to 200, more preferably from 1 to 100, still more preferably from 1 to 50, especially preferably from 1 to 25, even more especially preferably from 1 to 20, especially preferably from 1 to 15, and most preferably from 1 to 10.

[0154] PMDI can be a compound with a specific, ie discrete, value of n, or PMDI is a mixture of compounds of formula (II) with different n values.

[0155] The compound of formula (II) may also be an aromatic triisocyanate. An example of an aromatic triisocyanate is a compound of formula (XXX) where n is 1; they are known under the CAS number 9016-87-9. An example is the compound of formula (XXXI):

[0156] Isocyanates with an aromatic component may tend to hydrolyze more rapidly in situ than aliphatic isocyanates. Since the hydrolysis rate decreases at lower temperatures, isocyanate reactants are preferably stored at temperatures no higher than about 50°C. Isocyanate reactants containing an aromatic component are preferably stored at temperatures of no more than about 20 to about 25°C and in a dry atmosphere.

[0157] Other polyisocyanates are toluene diisocyanate adducts with trimethylolpropane, xylene diisocyanate and polymethylene polyphenyl polyisocyanate-terminated polyols.

[0158] Preferably, the isocyanate having at least two isocyanate groups is selected from the group consisting of compounds of formula (II), compounds of formula (IV), methylene di(phenyl isocyanate), compounds of formula (VIII), compounds of formula (XII), 1,5-naphthylene diisocyanate, hydrogenated methylene di(phenyl isocyanate), compounds of formula (XIX), compounds of formula (XXIV), compounds of formula (XXVI), compounds of formula (XXVIII), polymeric methylene di(phenyl isocyanate) and mixtures thereof.

[0159] The isocyanate having at least two isocyanate groups is preferably selected from the group consisting of methylene di(phenyl isocyanate), polymeric methylene di(phenyl isocyanate), hydrogenated methylene di(phenyl isocyanate), isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate and mixtures thereof.

[0160] Preferably, the lubricant in mixture A in step A) of the process of the present invention comprises one or more lubricating greases, one or more lubricating oils, one or more lubricating waxes, or mixtures thereof. More preferably, the lubricant in mixture A in step A) of the process of the present invention comprises one or more lubricating greases, one or more lubricating oils, or mixtures thereof. Even more preferably, the lubricant in mixture A in step A) of the process of the present invention comprises one or more lubricating oils, or mixtures thereof. The lubricant in mixture A in step A) of the process of the present invention may further comprise additives.

[0161] The lubricant in mixture A in step A) of the process of the present invention preferably does not comprise polyfluorinated chemicals (PFAs).

[0162] More preferably, the lubricant in mixture A in step A) of the process of the present invention consists of one or more lubricating greases, one or more lubricating oils, one or more lubricating waxes, or mixtures thereof, and optionally one or more additives. More preferably, the lubricant in mixture A in step A) of the process of the present invention consists of one or more lubricating greases, one or more lubricating oils, or mixtures thereof, and optionally one or more additives. More preferably, the lubricant in mixture A in step A) of the process of the present invention consists of one or more lubricating oils, or mixtures thereof, and optionally one or more additives.

[0163] In a preferred embodiment of the invention, the lubricating oil is selected from the group consisting of a mineral oil, a synthetic oil and a vegetable oil.

[0164] Preferably, the synthetic oil in mixture A in step A) of the process of the present invention is selected from the group consisting of an alkylated naphthalene, an ester oil, a multialkylated cyclopentane, a polyolefin, a polyphenyl ether, a polyglycol oil, a silicone oil, a polybutene, a polyol ester, a polyalkylene glycol, a phosphate ester, an alkane or paraffin, an alkene or olefin, a naphthene, a fluoride-free ionic liquid, and mixtures thereof. Particularly preferably, the synthetic oil is selected from the group consisting of an ester oil, a polyolefin, a polyol ester, a phosphate ester, an alkene or olefin, and mixtures thereof.

[0165] Likewise preferably, the vegetable lubricating oil in the mixture A in step A) of the process of the present invention is selected from the group consisting of linseed oil, soybean oil, sunflower oil, olive oil, safflower oil, rapeseed oil, tung oil, oiticica oil, castor oil, tall oil, palm oil, palm kernel oil, peanut oil, corn germ oil, coconut oil, sesame oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, castor oil, wheat germ oil, hemp oil, poppy seed oil, grape seed oil, walnut oil, rosehip oil, blackcurrant seed oil, kukui nut oil, perilla oil, isano oil, stillingia oil, lallemantia oil and cottonseed oil.

[0166] More preferably, the vegetable lubricating oil in mixture A in step A) of the process of the present invention is selected from the group consisting of soybean oil, sunflower oil, olive oil, safflower oil, rapeseed oil, castor oil, tall oil, palm oil, palm kernel oil, peanut oil, corn germ oil, coconut oil, sesame oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, wheat germ oil, hemp oil, poppy seed oil, grape seed oil, walnut oil, rosehip oil, blackcurrant seed oil, kukui nut oil, and cottonseed oil.

[0167] Even more preferably, the vegetable lubricating oil in mixture A in step A) of the process of the present invention is selected from the group consisting of sunflower oil, olive oil, rapeseed oil, castor oil, tall oil, palm oil, palm kernel oil, corn germ oil, coconut oil, sesame oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, wheat germ oil, and cottonseed oil.

[0168] Still preferably, the vegetable lubricating oil in the mixture A in step A) of the process of the present invention is selected from the group consisting of olive oil, castor oil, tall oil, palm oil, palm kernel oil, coconut oil, sunflower oil, babassu oil, avocado oil, jojoba oil, almond oil, wheat germ oil, and cottonseed oil.

[0169] Most preferably, the vegetable lubricating oil is selected in the mixture A in step A) of the process of the present invention from the group consisting of olive oil, castor oil, tall oil, palm oil, palm kernel oil, coconut oil, babassu oil, avocado oil, jojoba oil, and almond oil.

[0170] Preferably, the lubricating oil, more preferably the vegetable lubricating oil, in mixture A in step A) of the process of the present invention is a non-hardening lubricating oil. More preferably, the non-hardening lubricating oil, preferably a non-hardening vegetable lubricating oil, in mixture A in step A) of the process of the present invention has an iodine number below 140, more preferably below 100, measured according to ASTM D1541.

[0171] Hardening lubricating oils have the property of cross-linking over time, e.g., due to oxidation, but also due to UV light. This creates the risk that the core material will become more viscous or even harden after a certain storage period. Consequently, the lubricating oil can no longer escape from the shell during use, or only at a slower rate. Furthermore, the lubricating properties of the lubricating oil are reduced by cross-linking or are no longer suitable for the application window. As a result, the tribological functionality in mixture A in step A) of the process is lost over time. It has now been shown that this disadvantage can be remedied by using non-hardening lubricating oils, preferably non-hardening vegetable lubricating oils.

[0172] Preferably, at least one solvent is also mixed in step A).

[0173] The solvent is preferably selected from the group consisting of ethyl acetate, butyl acetate, xylene, MTBE, and toluene. The solvent is particularly preferably ethyl acetate or toluene.

[0174] In step A), mixture A is mixed to such an extent that at least a homogeneous distribution, ideally a solution of the components, is achieved.

[0175] Step B): Preparation of the emulsion

[0176] The polymerization (step C) of the present invention is carried out in an emulsion, particularly preferably in a two-phase emulsion. Therefore, such an emulsion is prepared in step B prior to polymerization. In exceptional cases, the emulsions may also be suspensions if the lubricants solidify before or during the formation of the suspension. However, the preparation of an emulsion is preferred.

[0177] The at least two-phase emulsion contains a first phase comprising mixture A and a second phase comprising, preferably consisting of, a protic phase. Lubricants can be as defined herein (paragraph "Microcapsules of the present invention" and "Step A: Mixing the isocyanate having at least two isocyanate groups with a lubricant").

[0178] Each emulsion and each suspension used in the polymerization of the present invention can be emulsified by the following methods: by application of shear and mixing force, which can be achieved by using appropriate stirring, mixing or dispersing means, such as high shear mixers, e.g. Ultra Turrax, mills, e.g. bead mills, use of ultrasonic waves and the like, and membrane technology, whether batchwise or inline, i.e. continuously.

[0179] The solvent for the first phase of the at least two-phase emulsion is preferably selected from the group consisting of ethyl acetate, butyl acetate, xylene, MTBE, and toluene. Most preferably, the solvent for the first phase of the at least two-phase emulsion is ethyl acetate or toluene.

[0180] The protic phase is a phase that is immiscible with the first phase. Preferably, the protic phase is a hydrophilic phase. More preferably, the protic phase contains at least one protic solvent, preferably selected from the group consisting of alcohol, amine, water, or mixtures thereof. The protic solvent is particularly preferably water.

[0181] The other components of the emulsion, such as the emulsion stabilizer, the catalyst, the at least one additive (as defined herein, see paragraph "Microcapsule of the present invention" and paragraph "Step C): Polymerization of the present invention") or the crosslinking agent (as defined herein, see paragraph "Step C): Polymerization of the present invention") can also be added to the second phase before emulsification.

[0182] Preferably, only the emulsion stabilizer is added to the second phase before emulsification, and all other required components (the catalyst, the at least one additive, the crosslinking agent) are added after emulsification of the emulsion. This prevents spontaneous crosslinking during emulsification. These components are preferably added in solution with the protic solvent.

[0183] In both cases, an emulsion is formed because these components dissolve in the second phase when added.

[0184] Step C): Polymerization of the present invention

[0185] Step C) of the production process of the present invention relates to a polymerization process for producing a polyurea, which is described in detail below. The polyurea of ​​the microcapsule of the present invention is produced by polymerizing an isocyanate having at least two isocyanate groups in the presence of a crosslinking agent (polymerization of the present invention). Preferably, in step C), the crosslinking agent is an amine having at least two amino groups (polyamine, C1) or water (C2). As described above, the crosslinking agent is added to the emulsion, and the reaction is initiated by adjusting the reaction conditions such as temperature, duration, and the presence of a catalyst.

[0186] Step C) can be carried out in the presence of an additive. The additive is preferably selected from the group consisting of gum arabic, polyalcohol, polyacrylate, unsaponified or partially saponified polyvinyl acetate, polyvinylpyrrolidone, cellulose ethers, starch, proteins, alginates, pectins, gelatin, polysaccharides, sodium or magnesium silicates, carboxymethylcellulose, acrylates and acrylic polymers, acrylate-aminoacrylate copolymers, arabinogalactan, carrageenan, water-swellable clays, maltodextrin, natural gums, protein hydrolysates and their quaternized forms, poly(vinylpyrrolidone-co-vinyl acetate), poly(vinyl alcohol-co-vinyl acetate), poly(maleic acid), maleic acid-vinyl copolymers, poly(alkylene oxide), poly(vinyl methyl ether), poly(vinyl ether-co-maleic anhydride), poly(ethyleneimine), poly((meth)acrylamide), poly(alkylene oxide-co-dimethylsiloxane), poly(aminodimethylsiloxane), Sodium lignosulfonates, maleic anhydride / styrene copolymers, ethylene / maleic anhydride copolymers,Copolymers of ethylene oxide, propylene oxide and ethylenediamine, fatty acid esters of polyethoxylated sorbitol and sodium dodecyl sulfate with polyalcohol.

[0187] Natural gums include xanthan gum, gellan gum, guar gum, and alginate esters. Polyacrylate can be an acrylic copolymer potassium salt. Cellulose ethers can be tylose, methylcellulose, hydroxyethylcellulose, or hydroxypropylmethylcellulose.

[0188] The one or more additives are preferably selected from the group consisting of gum arabic, polyalcohol, polyacrylate, unsaponified or partially saponified polyvinyl acetate, polyvinylpyrrolidone, cellulose ethers, starch, alginates, pectins, gelatin, polysaccharides, xanthan gum, sodium or magnesium silicate, carboxymethylcellulose and polyacrylic acids.

[0189] Most preferably, the additive is selected from the group consisting of gum arabic, polyalcohol, polyacrylate and polyvinylpyrrolidone.

[0190] The polyalcohol is a compound that contains two or more hydroxyl residues per molecule.

[0191] Preferably, the polyalcohol is selected from the group consisting of polyvinyl alcohol, poly(ethylene glycol), poly(propylene glycol), poly(ethylene glycol)-block-poly(propylene glycol), poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), ethylene glycol, propylene glycol, compounds of formula (XXXII) and mixtures thereof:

[0192] (XXXII) where n1 is an integer from 1 to 9.

[0193] Preferably, n1 is 1, 2, 3, 4 or 5.

[0194] Preferably, the polyalcohol is selected from the group consisting of polyvinyl alcohol, poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol), compounds of formula (XXXII) wherein n1 is 1, 2 or 3, and mixtures thereof.

[0195] Polyvinyl alcohol is commonly abbreviated as PVA.

[0196] Preferably, PVA has a molecular weight of 20,000 to 40,000 g / mol.

[0197] Poly(ethylene glycol) is usually abbreviated as PEG, while poly(propylene glycol) is usually abbreviated as PPG. Poly(ethylene glycol)-block-poly(propylene glycol) is usually abbreviated as PEG-PPG. Poly(ethylene glycol)-block-poly(propylene glycol)-block-poly(ethylene glycol) is usually abbreviated as PEG-PPG-PEG. PEG, PPG, PEG-PPG, and PEG-PPG-PEG can have an average molecular weight of 5000 to 6500 g / mol.

[0198] The crosslinking agent can also be a mixture of water, polyamine, and / or polyvinyl alcohol. The ratio of OH groups of the polyalcohol to isocyanate groups of the isocyanate is preferably no greater than 1:2, preferably no greater than 1:3, more preferably no greater than 1:5, and most preferably no greater than 1:10.

[0199] Preferably, the amine having at least two amino groups (C1) is selected from the group consisting of polyamine, ethylenediamine, diethylenetriamine, triethylenetetramine, trimethylhexamethylenediamine, 1,2-diaminocyclohexane, hexamethylenediamine, isophoronediamine, 4,4'-diaminodiphenylsulfone, 1,5-diamino-2-methylpentane, and mixtures thereof. More preferably, the amine having at least two amino groups (C1) is selected from the group consisting of trimethylhexamethylenediamine, 1,2-diaminocyclohexane, hexamethylenediamine, isophoronediamine, 4,4'-diaminodiphenylsulfone, and mixtures thereof.

[0200] Preferably, the polyamine is selected from the group consisting of compounds of formula (XXXIII), compounds of formula (XXXIV), compounds of formula (XXXV), compounds of formula (XXXVI), polymeric methylenedi(aniline), hydrogenated methylenedi(aniline), cystamine, triethyleneglycoldiamine, compounds of formula (XXXVII), compounds of formula (XXXVIII) and mixtures thereof:

[0201] (XXXVIII) where n2 is an integer from 1 to 9;

[0202] R10, R11, R12, R13, R14, R15, R35, R36, R37 and R38 are the same or different and are independently selected from the group consisting of H, halogen and C1-4-alkyl; n8 is an integer from 1 to 5, preferably from 0, 1, 2 or 3; n9 is 1, 2, 3, 4, 5, 6 or 7;

[0203] Y1 is selected from the group consisting of SS, (CH2)n6-Z1-(CH2)n6 and Z1-(CH2)n2-Z1; n6 is 0, 1, 2, 3 or 4, preferably 0, 1, 2 or 3;

[0204] Z1 is selected from the group consisting of NH, O and S; n17 and n18 are the same or different and are independently an integer selected from the group consisting of 0, 1, 2, 3 and 4; and

[0205] Halogen is preferably Cl, Br, F or I.

[0206] Preferably, n2 is 1, 2, 3, 4, 5, 6, 7, 8 or 9; more preferably, n2 is 1, 2, 3, 4, 5, 6, 7 or 8, still more preferably 2, 3, 4, 5 or 6, most preferably 2, 3, 4 or 5.

[0207] Preferably, R10, R11, R12, R13, R14, R15, R35, R36, R37 and R38 are the same or different and independently selected from the group consisting of H, F, Cl, methyl, ethyl and propyl.

[0208] The compounds of formula (XXXIV) are preferably polyethyleneamines, e.g. selected from the group of amines of the structure NH2(CH2CH2NH)n?CH2CH2NH2, and substituted and unsubstituted polypropyleneimines, where n7 is an integer from 1 to 5, preferably from 1 to 5, particularly preferably n7 is 1, 2 or 3.

[0209] Further examples of the polyamine are diethylenetriamine (molecular weight of about 103.17 g / mol, equivalent weight of about 34.4 g / mol), triethylenetetramine (molecular weight of about 146.23 g / mol, equivalent weight of about 36.6 g / mol), iminobispropylamine and bis(hexamethylene)triamine, triethyleneglycoldiamine (e.g., Jeffamine EDR-148 from Huntsman Corp., Houston, TX, with CAS 929-59-9), and the compound of formula (XXXIX):

[0210] (XXXIX)

[0211] Preferably, the compounds of formula (XXXV) are selected from the group consisting of the compound of formula (XXXV-1), the compound of formula (XXXV-2), the compound of formula (XXXV-3), the compound of formula (XXXV-4), the compound of formula (XXXV-5), the compound of formula (XXXV-6), the compound of formula (XXXV-7), the compound of formula (XXXV-8) and mixtures thereof.

[0212] (XXXV-6)

[0213] (XXXV-8)

[0214] Preferably, the compound of formula (XXXV) is selected from the group consisting of the compound of formula (XXXV-1), the compound of formula (XXXV-2), the compound of formula (XXXV-3), the compound of formula (XXXV-4), the

[0215] Compound of formula (XXXV-5), compound of formula (XXXV-6) and mixtures thereof.

[0216] Preferably, the compound of formula (XXXVI) is selected from the group consisting of the compound of formula (XXXVI-1), the compound of formula (XXXVI-2), the compound of formula (XXXVI-3), the compound of formula (XXXVI-4), the compound of formula (XXXVI-5), the compound of formula (XXXVI-6), the compound of formula (XXXVI-7), the compound of formula (XXXVI-8) and mixtures thereof.

[0217] (XXXVI-3)

[0218] (XXXVI-8)

[0219] Preferably, the compound of formula (XXXVI) is selected from the group consisting of the compound of formula (XXXVI-1), the compound of formula (XXXVI-2), the compound of formula (XXXVI-3), the compound of formula (XXXVI-4), the compound of formula (XXXVI-5), the compound of formula (XXXVI-6) and mixtures thereof.

[0220] Polymeric methylenedi(aniline) can be represented by the compound of formula (XXXX): where n3 is an integer from 1 to 500, preferably from 1 to 200, more preferably from 1 to 100, still more preferably from 1 to 50, especially preferably from 1 to 25, most preferably from 1 to 20, and most preferably from 1 to 15, especially from 1 to 10.

[0221] Polymeric methylenedi(aniline) can be a compound with a specific, i.e., a discrete value of n3, or polymeric methylenedi(aniline) is a mixture of compounds of formula (XXXX) with different n3 values.

[0222] Preferably, n17 and n18 are independently 0 or 1, particularly preferably n17 and n18 are 0.

[0223] Examples of compounds of formula (XXXVII) are meta-xylylenediamine with CAS number 1477-55-0, e.g. from Mitsubishi Gas Co., Tokyo, JP (molecular weight of about 136.19 g / mol; equivalent weight of about 68.1 g / mol), para-xylylenediamine, 2,3,5,6-tetramethyl-1,4-xylylenediamine, 2,5-dimethyl-1,4-xylylenediamine, the compound of formula (XXXI), the compound of formula (XXXXII), of which diethyltoluenediamine is an embodiment, such as with CAS 68479-98-1, the compound of formula (XXXXIII) and the compound of formula (XXXXIV): (XXXXIII)

[0224] (XXXXIV) where

[0225] R35 and R36 are the same or different and are H, CI or C1-4-alkyl, preferably H, methyl or ethyl, more preferably methyl or ethyl.

[0226] Examples of the compound of formula (XXXVIII) are isophoronediamine, hydrogenated meta-xylylenediamine, hydrogenated para-xylylenediamine, hydrogenated 2,3,5,6-tetramethyl-1,4-xylylenediamine, hydrogenated 2,5-dimethyl-1,4-xylylenediamine, compounds of formula (XXXXV), compounds of formula (XXXXVI), of which hydrogenated diethyltoluenediamine is an embodiment, compounds of formula (XXXXVII), and compounds of formula (XXXXVIII):

[0227] (XXXV)

[0228] (XXXXVI) (XXXXVII)

[0229] (XXXXVII I) where

[0230] R35 and R36 are the same or different and are H, CI or C1-4-alkyl, preferably H, methyl or ethyl, more preferably methyl or ethyl.

[0231] Preferably, the polyamine is selected from the group consisting of the compounds of formula (XXXIII), the compound of formula (XXXV)), polymeric methylenedi(aniline), hydrogenated methylenedi(aniline), isophoronediamine, the compound of formula (XXXVII), the compound of formula (XXXVIII) and mixtures thereof.

[0232] The polymerization process for producing a polyurea from an isocyanate with at least two isocyanate groups in the presence of water is well known: Water reacts with an isocyanate group, the reactions convert the isocyanate group into an amino group by releasing carbon dioxide, the resulting amino group can react with another isocyanate group to form a urea bond, and since more than one isocyanate group is present in the isocyanate, polymerization occurs. In this respect, polymerization in the presence of water represents polymerization with an in situ generated amine.

[0233] Preferably, step C) is carried out in the presence of an emulsion stabilizer. The emulsion stabilizer is preferably selected from the group consisting of non-ionic emulsion stabilizers, anionic emulsion stabilizers, cationic emulsion stabilizers, and mixtures thereof.

[0234] The ionic emulsion stabilizer is preferably selected from the group consisting of alkyl polyglycoside, cetomacrogol 1000, cetyl stearyl alcohol, cetyl alcohol, cocamide diethanolamine, cocamide monoethanolamine, decyl glucoside, decyl polyglucose, lauryl glucoside, maltoside, monolaurin, mycosubtilin, Nonidet P-40, nonoxynol-9, nonoxynol-40, octyl glucoside, oleyl alcohol, polysorbate 20, polysorbate 80, sorbitan monolaurate, sorbitan monostearate, sorbitan tristearate, stearyl alcohol, Triton X-100, Tween 80, polyvinyl alcohol, such as Mowiol 4-88, Mowiol 8-88, or polyvinylpyrrolidone, and mixtures thereof.

[0235] The anionic emulsion stabilizer is preferably selected from the group consisting of sodium lauryl sulfate, sodium lauryl ether sulfate, benzenesulfonic acid, sodium salt of benzenesulfonic acid, linear alkylbenzenesulfonate, alpha-olefin sulfonate, fatty alcohol sulfate, alkyl ether sulfate, secondary alkanesulfonate, and mixtures thereof.

[0236] The cationic emulsion stabilizer is preferably selected from the group consisting of gelatin, behentrimonium chloride, benzalkonium chloride, benzethonium chloride, benzododecinium bromide, carbethopendecinium bromide, cetalkonium chloride, cetrimide, cetrimonium bromide, cetrimonium chloride and mixtures thereof.

[0237] The non-ionic emulsion stabilizer is a high molecular weight non-ionic surfactant and is preferably selected from polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP).

[0238] Likewise, step C) is preferably carried out in the presence of a catalyst. The catalyst is preferably selected from the group consisting of DABCO, dimethylcyclohexylamine, dimethylethanolamine, triethylenediamine, N,N,N',N",N"-pentamethyldiethylenetriamine, 1,2-dimethylimidazole, N,N,N',N'-tetramethyl-1,6-hexanediamine, N,N',N'-trimethylaminoethylpiperazine, 1,1'-[[3-(dimethylamino)propyl]imino]bispropan-2-ol, N,N,N'-trimethylaminoethylethanolamine, and N,N',N"-tris(3-dimethylaminopropyl)hexahydro-s-triazine.

[0239] The catalyst is preferably DABCO or triethylenediamine.

[0240] Preferably the catalyst is DABCO.

[0241] The catalyst is used in the polymerization of the present invention when the second phase of the emulsion preferably comprises an aqueous medium. In such a second phase, the catalyst may remain in solution if its water solubility is sufficient. The catalyst is not intended to be part of the microcapsules of the present invention. However, it is possible for some or all of the catalyst to be contained in the microcapsules of the present invention, e.g., if the catalyst is adsorbed by the microcapsules of the present invention despite its water solubility. The catalyst may be present in the polymerization of the present invention in an amount of 1 to 200 wt.%, preferably 2 to 90 wt.%, more preferably 10 to 50 wt.%, especially 20 to 40 wt.%, where the wt.% is based on the weight of isocyanate having at least two isocyanate groups.

[0242] The catalyst can be added to the polymerization of the present invention as a solid, in the form of an aqueous solution, or in the form of an aqueous suspension. Preferably, the catalyst is added to the polymerization of the present invention in the form of an aqueous solution or in the form of an aqueous suspension. For example, the catalyst can be used dissolved or suspended in the water used in the second phase of the emulsion.

[0243] The polymerization of the present invention can be carried out in the presence of an additive as described above. The first phase or the second phase can comprise the additive. These additives can also be present in the first phase comprising the lubricant, preferably in dissolved or suspended form.

[0244] When the polymerization of the present invention is carried out in the presence of additives, the total amount of additives in the polymerization of the present invention is preferably 0.01 to 20 wt%, more preferably 0.01 to 15 wt%, even more preferably 0.01 to 10 wt%, especially 0.01 to 7.5 wt%, wherein the wt% is based on the weight of isocyanate having at least two isocyanate groups.

[0245] The minimum amount of additives in the polymerization of the present invention may also be 0.1 or 1 wt.% in combination with any embodiment of the upper ranges defined herein, so that in another embodiment the total amount of additives in the polymerization of the present invention is from 0.1 to 20 wt.%, preferably from 0.1 to 15 wt.%, more preferably from 0.1 to 10 wt.%, in particular from 0.1 to 7.5 wt.%, wherein the wt.% is based on the weight of isocyanate having at least two isocyanate groups.

[0246] In another embodiment, the total amount of additives in the polymerization of the present invention is from 1 to 20 wt.%, more preferably from 1 to 15 wt.%, even more preferably from 1 to 10 wt.%, especially from 1 to 7.5 wt.%, wherein the wt.% is based on the weight of isocyanate having at least two isocyanate groups. When additive is present in the second phase, the amount of additives in the second phase is preferably from 0.1 to 1.5 wt.%, even more preferably from 0.25 to 1.25 wt.%, even more preferably from 0.4 to 1.0 wt.%, wherein the wt.% is based on the weight of water in the second phase.

[0247] When additives are present in the first phase, the amount of additive in the first phase is preferably 0.01 to 0.5 wt%, more preferably 0.01 to 0.3 wt%, where the wt% is based on the weight of solvent in the first phase. In another embodiment, when additive is present in the first phase, the amount of additive in the first phase is preferably 0.1 to 0.5 wt%, more preferably 0.1 to 0.3 wt%, where the wt% is based on the weight of solvent in the first phase. In another embodiment, when additive is present in the first phase, the amount of additive in the first phase is preferably 1 to 0.5 wt%, preferably 1 to 0.3 wt%, where the wt% is based on the weight of solvent in the first phase.

[0248] When the polymerization of the present invention is carried out in a two-phase emulsion, the amount of second phase is preferably 1 to 100 times, more preferably 1 to 10 times, and most preferably 2 to 4 times the weight of the first phase.

[0249] Preferably, the reaction temperature of the polymerization of the present invention is 0 to 150 °C, more preferably 20 to 100 °C, even more preferably 40 to 95 °C, especially 50 to 85 °C, even more preferably 65 to 80 °C.

[0250] If the polymerization of the present invention is carried out at ambient pressure, the reaction temperature of the polymerization of the present invention is between 30 °C and the boiling point of the reaction mixture at ambient pressure, preferably between 40 °C and the boiling point of the reaction mixture at ambient pressure, more preferably between 50 °C and the boiling point of the reaction mixture at ambient pressure, in particular between 60 °C and the boiling point of the reaction mixture at ambient pressure, in particular from 65 °C to the boiling point of the reaction mixture at ambient pressure.

[0251] A particularly preferred reaction temperature is between 65 and 80°C. The pressure during the polymerization of the present invention is preferably ambient pressure. Of course, it is possible to provide an elevated pressure, e.g., by simply sealing the reaction apparatus or by applying pressure using an inert gas such as nitrogen or argon, in order to be able to carry out the polymerization of the present invention at a temperature higher than the boiling point of the reaction mixture at ambient pressure.

[0252] It is also possible that the polymerization of the present invention is carried out at a pressure which is below ambient pressure.

[0253] Preferably, the reaction time of the polymerization of the present invention is between 5 min and 10 h, preferably between 1 h and 5 h, more preferably between 1.5 h and 4 h.

[0254] Preferably, the proportion of lubricant in the polymerization of the present invention is 1 to 10 times, preferably 1 to 7.5 times, more preferably 1.5 to 5 times, especially 1.5 to 3 times, the weight of the isocyanate having at least two isocyanate groups.

[0255] Preferably, the amount of water in the polymerization of the present invention is at least 0.5 molar equivalents to the molar amount of isocyanate groups of isocyanate having at least two isocyanate groups.

[0256] Preferably, the amount of water in the polymerization of the present invention is 1 to 50 times, preferably 2 to 25 times, more preferably 5 to 10 times the weight of isocyanate having at least two isocyanate groups.

[0257] Preferably, the amount of solvent in the polymerization of the present invention is 0 to 20 times, preferably 0 to 10 times, more preferably 0.5 to 2 times, especially 0.6 to 1.5 times, the weight of isocyanate having at least two isocyanate groups.

[0258] After the polymerization of the present invention, the microcapsules of the present invention can be isolated using standard methods known to those skilled in the art, such as filtration, washing, and drying. During washing, redispersion of the microcapsules of the present invention in the washing medium is also possible. Preferably, the isolation, in particular filtration, is carried out while the reaction mixture is still hot. Removal of unwanted large particles can be achieved by prefiltration with a correspondingly large mesh size, before isolation of the microcapsules of the present invention is carried out by filtration with a correspondingly smaller mesh size.

[0259] During or after the polymerization of the present invention, any solvent is preferably removed from the reaction mixture of the microcapsules of the present invention or from the recovered microcapsules. Solvent removal can be accomplished by standard methods such as filtration, distillation, drying, or a combination thereof. Distillation can be performed, for example, at elevated temperature, under reduced pressure, or in the form of an azeotropic distillation such as steam distillation. and articles covering the Mi the

[0260] The invention also relates to a composition for casting and extruding, preferably extruding, or coating components, wherein the composition comprises a microcapsule according to the present invention. Coating preferably comprises plasma coating, powder coating, and wet coating, more preferably powder coating and wet coating.

[0261] The invention also relates to an article comprising the microcapsule according to or the composition according to the present invention.

[0262] The composition may be suitable for coating articles or for molding articles, for example, by casting or extrusion / production of cast films and injection molding. Preferably, the composition of the present invention comprises, in addition to the microcapsule of the present invention, a composite material. In the case of a composition for coating, this composite material is preferably a curable composite material. Likewise, in the case of a composition for extrusion and / or injection molding, this composite material is preferably a thermoformable composite material.

[0263] Curing composite materials are preferably selected from the group consisting of epoxy resin, polyurethane, polyurea, alkyd resin, silicone, polyacrylate-based resin or suspension, as well as starch and cellulose-based composite material.

[0264] Thermoformable composite materials are preferably selected from the group consisting of polyethylene (PE), polypropylene (PP), polystyrene (PS), polybutylene terephthalate (PBT), polyoxymethylene (POM), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), polylactide (PLA), polybutylene succinate (PBS), acrylonitrile butadiene styrene (ABS), polyamides (PA), polyetheretherketone (PEEK) and polyvinyl chloride (PVC), polyetheretherketone (PEEK), polyphenylene sulfide (PPS), polyetherimide (PEI), polyaryletherketone (PAEK), polyamideimide (PAI) and their copolymers as well as natural and synthetic rubbers that are processed by vulcanization.

[0265] Furthermore, the thermoformable composite materials can be dissolved in a suitable solvent, mixed with the microcapsules, and applied as a coating. The coating is cured by removing the solvent (e.g., by evaporation).

[0266] The present invention also relates to the use of a microcapsule according to the present invention as a lubricant in a composition, preferably in a coating composition, or in an article. The microcapsules are incorporated into a coating or article, preferably a composite material. If the coating and / or article is exposed to certain conditions, such as pressure and / or temperature, the microcapsules are damaged, the lubricant escapes, and can reduce friction locally.

[0267] Also, the microcapsule of the present invention can be used in a plasma coating process.

[0268] Finally, the present invention generally relates to the use of a composition according to the present invention for reducing friction between articles.

[0269] Experimental part

[0270] Measurement methods

[0271] Oil leak

[0272] Oil leakage is examined visually and haptically. In emulsions, oil leakage and coagulation of free oil droplets are visible to the naked eye. To better visualize the effect, the encapsulated oil is additionally stained with Oil Blue N. In solid particles, oil leakage is only visually detectable at higher levels. It has been shown that a haptic examination allows even visually invisible amounts to be perceived.

[0273] Friction coefficient

[0274] The samples were tested for friction and wear using an oscillating 100Cr6 steel ball. The experiments were conducted on a section of the center web of the polymer sample. The ball was pressed onto the samples with a normal force of 10 N. The ball oscillated on the stationary polymer samples at a frequency of 10 Hz and a displacement of 1 mm. The tests were conducted at room temperature and without the addition of a lubricant. The device was an Optimol SRV 4.

[0275] Method for determining particle size distribution (PSD), volume-related average particle size, D10, D50 and D90

[0276] D10, D50, and D90 refer to the particle diameter corresponding to 10%, 50%, and 90% of the volume-average particle size distribution, respectively. D50 is also referred to as the volume median diameter. The units for D10, D50, and D90 are micrometers unless otherwise stated.

[0277] The particle size distributions of the samples were measured with the Beckman Coulter LS 13 320 using a 5 mW laser diode with a wavelength of 750 nm. The instrument also features a secondary tungsten-halogen light source for the PIDS (Polarization Intensity Differential Scattering) system. The light from the tungsten-halogen lamp is projected through a series of filters corresponding to the wavelengths (450 nm, 600 nm, and 900 nm) and transmitted through two orthogonally aligned polarizers at each wavelength.

[0278] The device uses both Mie theory (light scattering for small particles) and Fraunhofer theory (light diffraction for large particles) to interpret the signals.

[0279] PIDS (Polarization Intensity Differential Scattering) technology enables the detection of very small particles with very good resolution. The PIDS measurements are added to the same deconvolution matrix used for diffraction sizing. The relative volume of particles in each size channel is determined by a solution to this matrix. The analysis is fully integrated, meaning that even though two methods are used, a single solution is obtained.

[0280] Samples are taken directly from the reaction slurry. There is no specific concentration at which the suspensions should be measured, as the optimal concentration depends on the particle size.

[0281] Based on the turbidity measurement, the machine determines the optimum particle concentration for measurement. The sample suspension is simply added (drop by drop) to the measuring cell with water until the correct—i.e., optimal—turbidity is reached, which is signaled by the device.

[0282] Each sample is measured both in its original state and after 2 minutes of sonication in an ultrasonic bath.

[0283] Materials and equipment DABCO CAS number: 280-57-9, 1,4-Diazabicyclo[2.2.2]octane commercially available from Merck KGaA

[0284] PVA CAS 9002-89-5, Mowiol 4-88, polyvinyl alcohol, MW 31,000, 86.7-88.7 mol% hydrolysis, commercially available from Merck KgaA

[0285] PVP Povidone 10000

[0286] Toluene CAS 108-88-3, ACS reagent, purity 99.5% or more

[0287] Ethyl acetate CAS number 141-78-6, ACS reagent, purity 99.5% or more

[0288] ULTRA-TURRAX T 25 digital ULTRA-TURRAX commercially available through IKAOR-Werke GmbH & CO. KG, Germany

[0289] VKS20 Desmodur VKS20, a mixture of diphenylmethane-4,4'-diisocyanate (MDI) with isomers and higher functional homologues (PMDI), commercially available from Covestro AG, Leverkusen, Germany

[0290] N3400 Desmodur N3400, aliphatic isocyanate prepolymer, commercially available from Covestro AG, Leverkusen, Germany

[0291] Rotifluid Precision Mechanics Oil. A low-viscosity lubricant for the finest mechanics, mineral oil-based, commercially available from CARL ROTH GmbH + Co. KG.

[0292] Maprenal 921 Melamine resin precondensate Maprenal 921 , commercially available from Ineos Manufacturing Deutschland GmbH

[0293] Lupamin 1595 polyvinylamine with Mw of <10 000 Da, commercially available from BASF SE

[0294] VP 874 synthetic white oil-based grease Elkalub VP 874, commercially available from ELKALUB - Chemie-Technik GmbH)

[0295] GLS931 Ester and alpha-polyolefin based gear grease GLS931, commercially available from ELKALUB - Chemie-Technik GmbH

[0296] Polyester resin DIEPAL UP 130, with hardener, commercially available on PHD- 24 PA12 Vestamid® commercially available from Evonik Industries

[0297] AG

[0298] Desmodur Z4470BA Cycloaliphatic polyisocyanate (IPDI trimer), commercially available from Covestro AG, Leverkusen, Germany

[0299] Desmodur W Monomeric cycloaliphatic diisocyanate, commercially available from Covestro AG, Leverkusen, Germany

[0300] Desmodur N3500 Aliphatic polyisocyanate (HDI allophanate / trimer), commercially available from Covestro AG, Leverkusen, Germany

[0301] Diethylenetriamine Aliphatic amine, commercially available from Merck

[0302] GaA

[0303] Isophoronediamine Cycloaliphatic amine, commercially available from Merck GaA

[0304] Hexamethylenediamine Aliphatic amine, commercially available from Merck GaA

[0305] Examples

[0306] Inventive example IE1

[0307] 10 g of VKS20 were dissolved in 30 g of ethyl acetate. 40 g of sunflower oil (colored with Oil Blue N) were added and mixed. This mixture was dispersed in 200 g of a 0.5 wt% PVA solution in water using an ULTRA-TURRAX® at 4000 rpm. Subsequently, 2 g of catalyst (DABCO), pre-dissolved in 10 g of water, were added. The emulsion was heated to 75 °C to 80 °C and stirred for 2 h. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was redispersed in water for further testing.

[0308] Inventive example IE2

[0309] 10 g of VKS20 was dissolved in 30 g of ethyl acetate. 40 g of sunflower oil (colored with Oil Blue N) was added and mixed. This mixture was dispersed in 250 g of a 0.5 wt% PVA solution in water using an ULTRA-TURRAX® at 4000 rpm. 10 g of isophoronediamine was dissolved in 250 g of water, and the pH was adjusted to 9 with concentrated hydrochloric acid. This solution was added to the previously prepared emulsion, which was heated to 75-80 °C and stirred for 2 h. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was redispersed in water for further testing.

[0310] Comparison example CE1

[0311] 40 g of sunflower oil was dispersed in 500 g of an aqueous solution of 0.4 g PVA and 13 g Maprenal 921 using an ULTRA-TUR RAX® at 4000 rpm for 2 min. The pH was adjusted to 4, and the emulsion was stirred with a magnetic stirrer for 2 h. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was redispersed in water for further testing or spread in a crystallization dish, dried overnight, and subsequently sieved through a 100 μm sieve.

[0312] Comparison example CE2

[0313] 10 g of VKS20 were dissolved in 60 g of ethyl acetate. 90 g of sunflower oil were added and mixed. This mixture was dispersed in 400 g of a 0.5 wt% PVA solution in water using an ULTRA-TURRAX® at 4000 rpm. 10 g of glycerol and 4 g of DABCO were added to the previously prepared emulsion, which was heated to 75-80 °C and stirred for 2 h. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was redispersed in water for further testing.

[0314] Inventive example IE3

[0315] 10 g of N3400 were dissolved in 30 g of ethyl acetate. 40 g of sunflower oil were added and mixed. This mixture was dispersed in 250 g of a 0.5 wt% PVA solution in water using an ULTRA-TURRAX® at 7000 rpm. 10 g of isophoronediamine were dissolved in 250 g of water, and the pH was adjusted to 9 with concentrated hydrochloric acid. This solution was added to the previously prepared emulsion, which was heated to 75-80 °C and stirred for 2 hours. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was spread in a crystallization dish and dried overnight. The powder was sieved through a 100 μm sieve. The resulting powder was free-flowing and showed no signs of free oil.

[0316] Inventive Example IE4: 12.5 g of VKS20 were mixed with 112.5 g of VP 874. This resulted in a homogeneous solution or nanosuspension. This mixture was added to 200 g of an aqueous 0.5 wt.% PVA solution, 0.4 g of DABCO (0.4 g) and 0.5 g of polyethyleneimine were added, and the mixture was dispersed with an ULTRA-TURRAX® at 20,000 rpm for 3 min. The mixture was then stirred for 3 h at 80°C. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was distributed in a crystallization dish and dried overnight. The powder was sieved through a 100 μm sieve. The resulting powder was flowable and showed no free oil characteristics.

[0317] Inventive example IE5

[0318] 1.4 g of VKS20 was dissolved in 2.6 g of toluene and mixed with 9 g of GLS931. This resulted in a homogeneous solution or nanosuspension. This mixture was dispersed in 40 g of a 0.5 wt% aqueous PVP solution using an ULTRA-TURRAX® at 15,000 rpm for 2 min. Subsequently, 0.5 g of DABCO (catalyst) was added, and stirring was continued for a further 3 h at 80 °C. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was spread in a crystallization dish and dried overnight. The powder was sieved through a 100 μm sieve. The resulting powder was free-flowing and showed no free oil characteristics.

[0319] Inventive example IE6

[0320] 2 g of VKS20 were dissolved in 6 g of ethyl acetate and mixed with 8 g of Rotifluid. This resulted in a homogeneous solution or nanosuspension. This mixture was dispersed in 40 g of a 0.5 wt% aqueous PVP solution using an ULTRA-TURRAX® at 15,000 rpm for 2 min. Then, 0.5 g of DABCO (catalyst) was added, and the mixture was stirred for a further 3 h at 80 °C. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The filter cake was spread in a crystallization dish and dried overnight. The resulting powder was flowable and showed no free oil characteristics.

[0321] Inventive example IE7

[0322] 1 g of Desmodur Z44 was dissolved in 10 g of ethyl acetate and mixed with 9 g of sunflower oil (SBO). This resulted in a clear solution. This mixture was dispersed in 60 g of a 0.5 wt% aqueous PVA solution using an ULTRA-TURRAX® at 7000 rpm for 2 min. Subsequently, 0.24 g of isophoronediamine (in 20 g of water, pH 12.52) and 0.5 g of DABCO (catalyst) were added, and the mixture was stirred for a further 3 h at 80 °C. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The resulting suspension was dried by spray drying. The resulting powder was flowable and showed no free oil characteristics.

[0323] Inventive example IE8

[0324] 1 g of Desmodur W was dissolved in 10 g of ethyl acetate and mixed with 9 g of sunflower oil (SBO). This resulted in a clear solution. This mixture was dispersed in 60 g of a 0.5 wt% aqueous PVA solution using an ULTRA-TURRAX® at 7000 rpm for 2 min. Subsequently, 0.65 g of isophoronediamine (in 20 g of water, pH 12.83) and 0.5 g of DABCO (catalyst) were added, and stirring was continued for a further 3 h at 80 °C. The suspension was filtered through a paper filter by vacuum filtration and washed with 200 ml of water. The resulting suspension was dried by spray drying. The resulting powder was flowable and showed no free oil characteristics.

[0325] Inventive example IE9

[0326] 1 g of Desmodur VKS20 was dissolved in 10 g of ethyl acetate and mixed with 9 g of Rotifluid. This resulted in a clear solution. This mixture was dissolved in 60 g of a 0.5 wt% aqueous PVA solution using an ULTRA-TURRAX® at 7000 rpm for

[0327] The suspension was dispersed for 2 min. Then, 0.38 g of diethyltriamine (in 20 g of water, pH 12.26) and 0.5 g of DABCO (catalyst) were added, and stirring was continued for another 3 h at 80 °C. The suspension was filtered through a coarse filter (100 ml) and passed through completely.

[0328] The suspension was vacuum filtered through a paper filter and washed with 200 ml of water. The filter cake was spread in a crystallization dish and dried overnight. The resulting powder was free-flowing and showed no signs of free oil. Light microscopy revealed defined microcapsules with a geometry typical of core-shell particles.

[0329] Comparison example CE3

[0330] 1 g of Desmodur N3500 was dissolved in 10 g of ethyl acetate and mixed with 9 g of Rotifluid. This resulted in a clear solution. This mixture was dissolved in 60 g of a 0.5 wt% aqueous PVA solution using an ULTRA-TURRAX® at 7000 rpm for

[0331] Dispersed for 2 minutes. Then, 0.23 g of DETA (in 20 g of water, pH 11.93) and 0.5 g of DABCO (catalyst) were added, and the mixture was stirred for a further 3 hours at 80 °C. The suspension had already strongly agglomerated during preparation. Passing it through a coarse filter (100 pm) resulted in the majority of the capsules remaining in the sieve (< 50% yield). Light microscopic examination clearly shows that the formation of defined capsules was not possible in this case.

[0332] Comparison example CE4

[0333] 1 g of Desmodur N3500 was dissolved in 10 g of ethyl acetate and mixed with 9 g of Rotifluid. This resulted in a clear solution. This mixture was dissolved in 60 g of a 0.5 wt% aqueous PVA solution using an ULTRA-TURRAX® at 7000 rpm for

[0334] Dispersed for 2 minutes. Then, 0.26 g of HDMA (in 20 g of water, pH 12.86) and 0.5 g of DABCO (catalyst) were added, and the mixture was stirred for another 3 hours at 80 °C. The suspension had already agglomerated during preparation. Passing it through a coarse filter (100 μm) resulted in the majority of the capsules remaining in the sieve (< 50% yield). Light microscopy clearly shows that the formation of defined capsules was not possible in this case.

[0335] Investigation of chemical-mechanical resistance:

[0336] The microcapsules from examples IE1, IE2, and CE3 were tested for their hydrolytic stability. This test represents an accelerated investigation into the stability of microcapsules during long-term storage in a product containing either acidic (e.g., fatty acids) or basic (e.g., talc, CaCO3) components, additives, and / or fillers.

[0337] 1 g of microcapsules of examples IE1, CE1, or CE2 were suspended in 9 g of water, and the pH was adjusted to 2 or 13 with HCl or NaOH, respectively. The resulting suspensions were sealed with a plastic cap and heated to 70 °C in an oil bath and stirred with a magnetic stirrer for one week.

[0338] The microcapsules based on melamine resin and polyurethane (examples CE1 and CE2) showed the formation of oil droplets on the surface of the suspension at acidic and basic pH values ​​(see Figure 1). Polyurea-based microcapsules did not show any free oil droplets.

[0339] Investigation of resistance during processing in coatings and casting resins:

[0340] Microcapsules from example IE6 (5 g) were incorporated into polyester resin (45 g) using an Ultra-Turrax (10000 rpm, 60 s). The bubbles were separated using an ultrasonic bath for

[0341] 2 minutes. A portion of the mixture was allowed to stand. After one hour, no oil droplets were observed. This indicates sufficient stability to the solvent (styrene). Hardener was added to the other portion using a spatula, the mixture was poured into the Petri dishes, and cured. Alternatively, a metal disc was coated with the same composition (3 mm thick) and cured for 24 hours. For comparison, the same bodies were fabricated from polyester resin without microcapsules. All bodies (with and without microcapsules) have the same feel; no free oil was detected.

[0342] The friction coefficient for microcapsule-containing composites and coatings was 0.15±0.02, whereas for the composites without capsules it was 0.8±0.02.

[0343] Extrusion stability testing: 10 wt. % microcapsules from Example IE6 were mixed with PA12 powder and processed in a twin-screw extruder. The resulting polymer strands or granules were non-oily, indicating stable incorporation of microencapsulated lubricating oil.

[0344] For comparison, microcapsules from comparative example CE1 were thermoplastically processed using the same procedure. The oil leakage could be visually monitored during extrusion.

Claims

Claims 1. A microcapsule comprising a core and a shell surrounding the core, wherein the core comprises a lubricant and wherein the shell comprises a polyurea.

2. The microcapsule according to claim 1, wherein the lubricant comprises a lubricating oil.

3. The microcapsule according to claim 2, wherein the lubricating oil is a non-hardening lubricating oil.

4. The microcapsule according to any one of the preceding claims, wherein the polyurea is a polymer having a structural unit according to formula (I):

5. The microcapsule according to claim 4, wherein in formula (I) R and / or R' are a cycloaliphatic or aromatic hydrocarbon residue.

6. The microcapsule according to claim 5, wherein the polyurea is prepared by crosslinking an isocyanate having at least two isocyanate groups with a crosslinking agent.

7. A method for producing a microcapsule, the method comprising the following steps A) Mixing an isocyanate having at least two isocyanate groups, preferably in a mixture with a solvent, with a lubricant, thereby producing mixture A, B) preparing an at least two-phase emulsion, wherein a first phase of the emulsion comprises the mixture A and a second phase of the emulsion comprises a crosslinking agent, C) Crosslinking the isocyanate with the crosslinking agent to form a polyurea.

8. The process according to claim 7, wherein in step C) the crosslinking agent is an amine having at least two amino groups (C1) or water (C2).

9. The process according to any one of claims 7 or 8, wherein the isocyanate having at least two isocyanate groups is selected from the group consisting of isocyanate monomers, isocyanate trimers, biuret isocyanates, isocyanurates, polymeric isocyanates, and mixtures thereof.

10. The method according to any one of claims 7 to 9, wherein the two-phase emulsion further comprises an emulsion stabilizer selected from the group consisting of non-ionic emulsion stabilizers, anionic emulsion stabilizers, cationic emulsion stabilizers, and mixtures thereof.

11. Use of a microcapsule according to any one of claims 1 to 6 as a lubricant in a composition for casting, coating or extruding articles.

12. Use of a microcapsule according to one of claims 1 to 6 in a coating process, preferably a powder, wet or plasma coating process.

13. A composition for casting, coating or extruding components, the composition comprising a microcapsule according to any one of claims 1 to 6.

14. Use of a composition according to claim 13 for reducing friction between articles.

15. An article comprising the microcapsule according to any one of the preceding claims 1 to 6 or the composition according to claim 13.

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