Silicic-acid-based coating composition with Anti-adhesion property

Abstract

The present invention relates to a coating composition comprising: - at least one silicic acid coated with at least one release agent as component A; - at least one matrix-forming polymer as component B; - optionally, at least one solvent; and - optionally, at least one filler.

Description

[0001] Coating composition with non-stick properties based on silicas

[0002] The present invention relates to a coating composition for producing a non-stick coating, an object with such a non-stick coating, a method for producing it and its use in the manufacture of cooking, frying and kitchen appliances or other applications where a non-stick property is required.

[0003] Non-stick coatings have been known for more than twenty years. For example, these non-stick coatings contain one or more highly fluorinated polymers for non-stick properties, e.g., polytetrafluoroethylene (PTFE).

[0004] Non-stick coatings can be formulated for application and use in one or more layers. For a single-layer coating, all the above-mentioned requirements must be met in a single layer.

[0005] However, because fluorocarbon polymers are thermoplastic, it is difficult to make these non-stick coatings resistant to abrasive wear. Due to these limitations, cookware and bakeware coated with conventional fluorocarbon polymer non-stick coatings are susceptible to damage and abrasion under normal use.

[0006] The combination of silicone resins and silicone oils for release coatings has been used in practice for several years. Such combinations are particularly suitable due to their release properties across a wide range of foodstuffs and their good resistance. An example is the composition described in EP 1 072 660.

[0007] (A) 100 parts by weight of one or more polysiloxane resins of the general formula

[0008] R a Si(OR')bO(4 -ab / 2) with 0 <a<2, 0<b<2 und a+b<4,

[0009] (B) 0.05 to 10 parts by weight of one or more linear and / or branched polysiloxanes of the formula R"O-[R'"2Si-O]nR' and

[0010] (C) 5 to 80 parts by weight of a polyester containing hydroxyl groups, wherein R a , R',

[0011] R" and R'" each independently represent an alkyl group with 1 to 8 C atoms or an aromatic group with 6 to 20 C atoms, and n represents a number in the range of 4 to 5000.

[0012] The disadvantage of this coating is its rapidly diminishing non-stick properties.

[0013] There is therefore a need for sustainable, non-organo-fluorine-based compositions for the production of long-lasting non-stick coatings, especially for cookware such as pots, pans and baking tins, where the side that comes into contact with food is coated with a non-stick coating.

[0014] The problem described above is solved by the subject matter of the independent patent claims.

[0015] Long-lasting, as used in the invention, means that the non-stick property, tested in accordance with DIN EN 13834 - Annex C, has approximately the same initial non-stick level after the second test cycle, or that the non-stick property does not change significantly from the initial non-stick level after the second test cycle.

[0016] “Non-organo-fluoro-based” means that the addition of fluorinated polymers, such as polytetrafluoroethylene (PTFE), is avoided.

[0017] The present invention relates in one aspect to a coating composition, in particular a non-stick coating composition. The coating composition comprises at least one silica compound coated with at least one release agent and at least one matrix-forming polymer. Optionally, at least one solvent and / or at least one filler may be added.

[0018] Furthermore, the present invention relates to a non-stick coating produced from the coating composition. It would also be desirable if the silica according to the invention exhibited good compatibility with the silicone polyester. This property was unexpectedly discovered by measuring the gloss level.

[0019] Another object of the present invention is articles with a surface, preferably cookware or other household and utility items, which are coated with a non-stick coating made from the coating composition according to the present invention.

[0020] In a further aspect, the present invention relates to a method for producing the coating composition according to the invention, in which in a first step at least one silica is coated / treated with at least one release agent and in a further step the silica treated with a release agent is embedded in a polymer matrix.

[0021] In another aspect, the present invention relates to the use of the coating composition according to the invention for coating cookware for cooking, frying and / or baking.

[0022] Furthermore, the present invention relates to the use of a silica which is coated with a release agent to improve the non-stick properties of a non-stick coating.

[0023] Further aspects of the present invention and preferred embodiments will become apparent from the following detailed description and the wording of the patent claims.

[0024] Surprisingly, a coating produced from the coating composition according to the invention exhibits excellent non-stick properties, also has good adhesion to substrates such as metal, glass or ceramic, and exhibits good mechanical strength, such as scratch and abrasion resistance.

[0025] Detailed description

[0026] In a first aspect, the present invention relates to a coating composition comprising - at least one silica coated with at least one release agent, as component A;

[0027] - at least one matrix-forming polymer as component B;

[0028] - optionally at least one solvent; and

[0029] - optionally at least one filler.

[0030] Preferably, the coating composition according to the invention is not organo-fluorine based.

[0031] Surprisingly, it was found that a coating made from the coating composition according to the invention has a long-lasting good non-stick property, despite the absence of organo-fluorine-based matrices.

[0032] Preferably, the silica is selected from the group consisting of precipitated silica and pyrogenic silica, and mixtures thereof, or silicates.

[0033] The silicon dioxide particles can preferably be surface-modified or non-surface-modified.

[0034] Silica and silicon dioxide, as well as their particles, are to be used synonymously.

[0035] Preferably, the silicon dioxide particles have a specific surface area of ​​25–400 m². 2 / g, preferably 100 - 280 m 2 / g. The specific surface area, also called BET surface area in simplified terms, is determined according to DIN 9277:2014 by nitrogen adsorption using the Brunauer-Emmett-Teller method.

[0036] The silicon dioxide used for the invention can have a tapped density of up to 400 g / L, preferably from 30 to 300 g / L. Tapped densities of various powdered or coarse-grained granular materials can be determined according to DIN ISO 787-11:1995 "General test methods for pigments and fillers - Part 11: Determination of tapped volume and tapped density". In this method, the fill density of a bulk material is measured after vibration and tamping.

[0037] Preferably, the non-surface-modified pyrogenic silicas are those with the following physicochemical properties: a BET surface area of ​​150 to 400 m². 2 / g, a tapped density of 40 to 300 g / l and

[0038] Pyrogenic silicas are produced by flame hydrolysis of silicon compounds. In this process, a hydrolyzable silicon compound is reacted in a flame generated by the combustion of hydrogen and an oxygen-containing gas. The combustion flame provides water for the hydrolysis of the silicon halide and sufficient heat for the hydrolysis reaction. This process typically forms aggregates that constitute a three-dimensional network. Several aggregates can form agglomerates. Pyrogenic silica produced in this way is called pyrogenic hydrophilic silica. Silicas obtained directly from the flame process have a BET surface area of ​​150 to 400 m². 2 / g exhibit a low tapped density and high thickening in coatings. In a preferred embodiment, their BET surface area is 160 to 330 m². 2 / g and the tapped density 100 to 250 g / l.

[0039] The silica of the preferred embodiment can be produced, for example, by grinding the silica obtained directly from the flame process as described above.

[0040] According to the invention, the following pyrogenic surface-modified and structure-modified silicas can preferably be used.

[0041] Preferably, the silicon dioxide particles have a surface modification with silanes selected from dimethyldichlorosilane, trimethylmonochlorosilane, methyltrichlorosilane, propyltrichlorosilane, trimethoxypropylsilane, triethoxypropylsilane, trimethoxy-i-butylsilane, triethoxy-i-butylsilane, trimethoxyoctylsilane, triethoxyoctylsilane, trimethoxyhexadecylsilane, octyltriethoxysilane and triethoxyhexadecylsilane, silazanes selected from 1,1,1-trimethyl-N-trimethylsilylsilanamine and N-methyl-aza-2,2,4-trimethylsilacyclopentane or siloxanes selected from octamethyltetracyclosiloxane, decamethylpentacyclosiloxane, dodecamethylhexacyclosiloxane, methoxy- and hydroxy-terminated polydimethylsiloxane, or combinations thereof. Such surface-modified silicon dioxide particles are available, for example, under the name AEROSIL® (Evonik), Cab-o-sil® (Cabot) or HDK (Wacker).Preferably, the pyrogenic surface-modified and structure-modified silicas exhibit the following physicochemical properties:

[0042] BET surface m 2 / g: 25 - 400,

[0043] Average size of primary particles (nm): 5 - 50, pH value: 3 - 10,

[0044] Carbon content %: 0.1 - 25, determined using LECO according to ISO 3262-19

[0045] DBP value %: The DBP value is at least 10% lower than the DBP value of the corresponding silanized, non-structurally modified silica. In cases of very strong structural modification, the structure can degrade to such an extent that the DBP value can no longer be determined.

[0046] It is also conceivable to use other metal oxides, such as zinc oxides, titanium dioxides and aluminum oxides.

[0047] Preferably hydrophilically precipitated silicic acids and silicates exhibit the following physicochemical properties:

[0048] BET surface area: 5 - 500 m² 2 / g, preferably 5 - 300 m 2 / g, especially preferred 5 - 250 m 2 / G,

[0049] DOA: 50 - 400 ml / 100g, preferably: 50 - 240 ml / 100g, determined according to ISO 19246,

[0050] Dso: 0.5-50 pm, preferably: 0.5-20 pm, , determined by laser diffraction at a Coulter LS according to ISO 13320,

[0051] Tapped density: 30 - 400 g / L, preferred: 30 - 250 g / L,

[0052] Loss on ignition according to DIN EN ISO 3262-20: < 6 wt.%.

[0053] Preferably, these are selected from hydrophilic, hydrophobic and / or partially hydrophobic, pyrogenic and / or precipitated silicon dioxides.

[0054] The term "hydrophilic" as used in the present invention refers to particles that can be completely wetted by pure water. Hydrophobic particles cannot be wetted by pure water; they therefore possess water-repellent properties. Such hydrophobicity can usually be achieved by applying appropriate nonpolar groups to the silica surface. The degree of hydrophobicity of a silica can be determined, among other things, by its methanol wettability according to Corning Glass, as described in more detail, for example, in WO2011 / 076518 A1, pages 5-6. In pure water, a completely hydrophobic silica separates from the aqueous phase and floats on its surface without being wetted. In pure methanol, on the other hand, a hydrophobic silica can be wetted by shaking or vigorous stirring and thus homogeneously distributed in the solvent volume.When measuring methanol wettability, the maximum methanol content in a methanol-water test mixture is determined at which the silica is just barely not wetted; ideally, 100% of the silica remains unwetted and separates after contact with the test mixture. This methanol content in the methanol-water mixture, expressed as a percentage by volume, is called methanol wettability. The higher the methanol wettability, the more hydrophobic the silica. Conversely, the lower the methanol wettability, the lower the hydrophobicity.

[0055] The hydrophilic silicon dioxide according to the invention preferably exhibits a methanol wettability of 0 vol% methanol in a methanol-water mixture. The silica is therefore completely wetted by pure water.

[0056] The hydrophobic silicon dioxide according to the invention preferably has a methanol wettability of > 0 vol% methanol in a methanol-water mixture, preferably it is between 5 - 90 vol% methanol in a methanol-water mixture, and particularly preferably between 20 - 75 vol% methanol in a methanol-water mixture.

[0057] Structure-modified AEROSIL® grades, available from Evonik, were introduced more than 10 years ago to improve the scratch resistance and mechanical resistance of products in the coating and adhesive / sealant industries.

[0058] Preferably, the pyrogenic silicon dioxide particles have a numerical mean primary particle size between 2 and 100 nm, preferably 5 and 50 nm. The numerical mean particle size can be determined by electron microscopy.

[0059] The silicas described above are known in themselves and to those skilled in the art in this field.

[0060] Coating compositions according to the invention, containing the silicas according to the invention, exhibit particularly pronounced non-stick properties. The more silica particles coated / treated with release agent are embedded in the polymer matrix, the better the non-stick properties of the resulting non-stick coating.

[0061] The silicas described above allow for loading and / or impregnation with release agents, resulting in particularly pronounced non-stick properties. Preferably, the loading and / or impregnation of the silica with release agents is carried out before mixing with component B, i.e., in a prior process step.

[0062] In the coating composition according to the invention, the silica, which is treated and / or coated with a release agent, is used either individually or in the form of a mixture of two or more silicas.

[0063] To improve the non-stick properties and to improve the mechanical properties, preferably at least one silica coated with a release agent and / or covered with a release agent is coated with a release agent in the coating composition according to the invention.

[0064] Release agent, release oil and silicone oil are used synonymously here.

[0065] The terms "Beaufschlagung", "Beladung" and "Besetzen", as well as corresponding verbs and adjectives, are used as synonyms.

[0066] The release agent is preferably a silicone oil, preferably compounds according to formula (I) or mixtures thereof:

[0067] Ma M a1 DD b1 Tc Qd Formula (I) with

[0068] M = (R1 3SiOi / 2)

[0069] M' = (R 2 R 1 2SiOi / 2)

[0070] D = (R 1 2SiO 2 / 2 )

[0071] D' = (R 2 R 1 SiO 2 / 2 )

[0072] T = (R 3 SiO 3 / 2 ) Q - (SiO4 / 2) a = 0 to 40, preferably 0 to 12, a1 = 0 to 40, preferably 0 to 20 b = 5 to 1000, preferably 5 to 800, in particular 5 to 200, b1 = 0 to 30, preferably 1 to 15, c = 0 to 40, preferably 0 to 20, in particular 0 to 10, d = 0 to 20, preferably 0 to 12, in particular 0 to 5,

[0073] R 1 = independently identical or different linear or branched, optionally aromatic hydrocarbon residues with 1 to 30 carbon atoms, preferably methyl, ethyl, propyl, aralkyl and / or aromatic residue, dodecyl or hexadecyl, in particular methyl and phenyl,

[0074] R 2= independent of each other identical or different organic polyether, hydride, hydroxy, amine, carboxy, alkoxy, epoxy, acetoxy, alkylalkoxysilylalkyl or alkoxysilylalkyl residues,

[0075] R 3 = R 1 or R 2 , preferably methyl, ethyl, propyl, aralkyl and / or aromatic residues, or alkoxy residues, in particular methyl and phenyl residues.

[0076] Preferably formula (I) has at least one R 2 on.

[0077] Preferably, the siloxanes of formula (I) can have the same or different residues R 2 exhibit, selected from the group consisting of

[0078] with m = 6 to 20, preferably 8 to 18, n = 2 to 18, preferably 4 to 8, o = 0 to 30, preferably 2 to 20, in particular 5 to 15, p = 0 to 30, preferably 0 to 10, q = 0 to 30, preferably 2 to 20, in particular 5 to 15, r = 0 to 30, preferably 0 to 10, s = 0 to 10, preferably 1 to 5, t = 1 to 20, preferably 1 to 10, u = 1 to 10, preferably 2 to 4, v = 1 to 10, preferably 2 to 5, w = 1 to 6, preferably 1 to 3. Such structures according to formula (I) and their fabrication are described, for example, in WO 2011 / 088937 A1, EP 2 176 319 B1, EP 1 072 660 A2 and EP 2 159 248 B1 are described and can be used.

[0079] The silica treated with the release agent preferably has a lower specific surface area after treatment / loading than the specific surface area of ​​the starting silica used.

[0080] The coating composition according to the present invention further preferably comprises a polymer for forming a matrix, which preferably forms the basic structure of the (later) non-stick coating and in which the silica particles treated with release agent and optionally the fillers are preferably embedded and preferably uniformly distributed in the polymer matrix.

[0081] Preferably, the matrix polymer as component B is selected from the group consisting of silicone resins, silicone polyester resin, polyethersulfone and polyamide-imide resin.

[0082] The silicone resins are preferably polymeric compounds according to formula (II),

[0083] R 5 eSi(OR 6 ) f O(4-ef) / 2 Formula (II) where e is greater than or equal to 0 but less than or equal to 2 and f is greater than or equal to 0 but less than or equal to 4, and the sum of e + f is less than 4. The R 5are independent of one another, identical or different linear or branched, saturated as well as mono- or polyunsaturated or aromatic hydrocarbon residues, or an organic group consisting of 1 to 8 carbon atoms and 1 to 2 nitrogen or oxygen atoms. R 6 R is a hydrogen atom or an alkyl group consisting of 1 to 8 carbon atoms. Preferably, R is a hydrogen atom or an alkyl group consisting of 1 to 8 carbon atoms. 5 a methyl, propyl, phenyl, 3-aminopropyl, or octyl group. Preferably, R is 6 around a hydrogen atom, a methyl or ethyl group.

[0084] Formula (II) represents the smallest unit of the average structural formula of the silicone resin. It is also conceivable to use a silicone resin as follows: The inorganic binder—an alkoxysilane compound or an alkylated alkoxysilane compound—is a condensation product of alkoxysilanes and optionally alkylated alkoxysilanes and can be prepared from it under acid or acid ester catalysis. The reactants used can preferably be alkoxysilanes of the generic formula Si(OR₂). 7 )4 with R 7 = organic residue and alkylated alkoxysilanes of the generic formula SiR 8 (OR 7 )3 with R 8 and R 7 = organic residue. The corresponding reaction can be carried out particularly efficiently in water. The reaction can be carried out particularly efficiently with phosphoric acid esters, preferably with monomethyl phosphates. Preferably, alkoxysilanes of the generic formula Si(OR) can be used as reactants.7 )4 and alkylated alkoxysilanes- SiR 8 (OR 7 )3 with R 8 or R 7 = -CH3,— CH2CH3, -CH2CH2CH3, -CH(CH3)2 are used. Even if the reaction is carried out in the presence of water, it is generally the case that after its action has ceased, i.e., after the formation of the binder, water is present only in very small proportions, typically <5 wt.%, in particular <2 wt.%, and furthermore, in particular <1 wt.%, based on the total mass of the coating composition.

[0085] The resulting binder of the genus formula R 8 iSiO«4-ij) / 2)(OR 7 )j with i > 0 and < 2, j > 0 and < 4 and i+j < 4 accordingly preferentially indicates R 8 and R 7 Residues = — CH3, — CH2CH3, — CH2CH2CH3, — CH(CH3)2, preferably R 8 and R 7= — CH3 and / or — CH2CH3 in the described generic formula is the smallest unit of the averaged structural formula of the resulting binder.

[0086] Particularly good coatings with exceptionally low brittleness can be achieved by using a mixture of SiCH3(OCH2CH3)3 and Si(OCH2CH3)4. The resulting binders accordingly exhibit the residuals R 8 and R 7 = -CH3 and / or -CH2CH3.

[0087] The matrix of the polyorganosiloxane hybrid resin is a polyorganosiloxane modified with organic polymer.

[0088] The polyorganosiloxane hybrid resin is particularly preferably a reaction product of a composition containing

[0089] Component A) 5 to 95 parts by weight, preferably 10 to 70 parts by weight, of one or more polyorganosiloxanes of general formula R aSi(OR')bO(4 -ab / 2) formula (III) with 0 <a<2, 0<b<2 und a+b<4, und

[0090] Component B) 5 to 95 parts by weight, preferably 30 to 90 parts by weight of an organic polymer, wherein

[0091] R a , each independently representing an alkyl group with 1 to 8 C atoms or an aromatic group with 6 to 20 C atoms, and n representing a number in the range of 4 to 250.

[0092] The polyorganosiloxane hybrid resins can be produced in a known manner. Common processes can be found in DE 10 2013 218976 A1, DE 10 2013 218981 A1, US 3,154,597, or US 3,170,962. Those skilled in the art will be familiar with further literature, such as "Silicone resins and their combination" by Wernfried Heilen, Chapter 2.2 Silicone combination resins / silicone resin hybrids, 2015, or "High Silicones and Silicone-modified Materials strength Silicone-Urethane Copolymers: Synthesis and Properties," Chapter 26, pp. 395-407.

[0093] For example, either a polyorganosiloxane is reacted with a hydroxy group-containing organic polymer, or the organic polymer is produced in the presence of the polyorganosiloxane by suitable monomers, or an organic polymer with alkoxysilane functionality is produced by hydrolysis / condensation or equilibration with alkoxysilane monomers or siloxane oligomers.

[0094] Preferably, the polyorganosiloxane is a linear, simply or multiply branched Si-OH or SiORi- functional polyorganosiloxane.

[0095] Polyorganosiloxanes are also referred to in the literature as siloxane oligomers, alkoxy-functional methyl, phenyl, and methyl / phenyl siloxanes, hydroxy-functional methyl, phenyl, and methyl / phenyl silicone resins, or silanols. Alkoxy-functional methyl, phenyl, and methyl / phenyl siloxane oligomers are available from ShinEtsu, among others under the trade names KC-89S, KR-500, X 40-9225, X 40-9246, X 40-9250, KR-401N, X-40-9227, KR-510, KR-9218, and KR-213.

[0096] Methoxy-functional methyl, phenyl, and methyl / phenyl siloxanes are available from Dow Corning under the trade names Dow Corning® LIS-CF 2403 Resin, LIS-CF 2405 Resin, 3037 Intermediate, 3074 Intermediate, and RSN-5314 Intermediate. Silanol-functional methyl / phenyl resins are marketed under the trade names RSN-0409 HS Resin, RSN-0431 HS Resin, RSN-0804 Resin, RSN-0805 Resin, RSN-0806 Resin, RSN-0808 Resin, and RSN-0840 Resin.

[0097] Alkoxy-functional methyl / phenyl, phenyl and methyl silicone resins, which are also offered hydrolyzed to the corresponding silanol, are available under the trade name SILRES® from Wacker Chemie, such as with the additional designations REN 50, REN 60, REN 80, KX, HK 46, MSE 100 or SY 300, IC 836, REN 168, SY 409, IC 232, SY 231, IC 368, IC 678.

[0098] The production of such silicone resins has long been known in the literature (see W. Noll - Chemie und Technologie der Silicone, Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim, 1960) and is also described in the German patent DE 34 12 648.

[0099] Preferably, the organic polymer is polyepoxides, polyesters, polyacrylates and / or methacrylates and copolymers thereof, polyurethanes, cellulose derivatives, polysulfones, polyethersulfones, polyphenylene sulfides and oxides, polyamides, polyamide-imide, polyimides, polyethers, aromatic and aliphatic glycidyl-functional polymers, oligomers, phenoxy resins, polycarbonates, ketone formalaldehyde resins, polyvinyl resins selected from polyvinyl alcohol, polyglycerols, polyvinyl acetate, their (partial) hydrolysates and derivatives, phenolic resins, alkyd resins and mixtures thereof.

[0100] Preferably, polyesters are used, selected from the reaction products of aromatic and / or aliphatic and / or cycloaliphatic monocarboxylic acids and / or dicarboxylic acids and / or polycarboxylic acids as well as their anhydrides and / or esters with linear and / or branched, aliphatic and / or cycloaliphatic and / or aromatic diols and / or polyols. Examples of common carboxylic acids are phthalic acid, phthalic anhydride, dimethyl terephthalate, isophthalic acid, terephthalic acid, 1,4-cyclohexanedicarboxylic acid, succinic acid, succinic anhydrides, sebacic acid, maleic acid, maleic anhydride, fumaric acid, methyltetrahydrophthalic acid, methyltetrahydrophthalic anhydride, methylhexahydrophthalic acid, methylhexahydrophthalic anhydride, hexahydrophthalic acid, tetrahydrophthalic acid, dodecanedioic acid, adipic acid, azelaic acid, isononanic acid, 2-ethylhexanoic acid, pyromellitic acid, pyromellitic dianhydride, and trimellitic acid.and / or trimellitic anhydride. Examples of common diols and / or polyols are ethylene glycol, 1,2- and / or 1,3-propanediol, diethylene, dipropylene, triethylene, tetraethylene glycol, 1,2- and / or 1,4-butanediol, 1,3-butylethylpropanediol, 1,3-methylpropanediol, 1,5-pentanediol, cyclohexanedimethylimethanol, glycerol, hexanediol, neopentyl glycol, trimethylolethane, trimethylolpropane and / or pentaerythritol, as well as bisphenol A, B, C, F, norbornylene glycol, 1,4-benzyldimethanol and ethanol, 2,4-dimethyl-2-ethylhexane-1,3-diol and 2,5-furandicarboxylic acid.

[0101] Epoxy resins with at least two 1,2-epoxy groups per molecule are preferably used. Examples of suitable epoxy resins are aliphatic or aromatic epoxides: Eponex® and EPON® resins from Hexion, Epalloy® resins from Emerald Performance Materials Company, Epotec® resins from Aditya Birla Chemicals, Denacol® resins from Nagase ChemteX, Araldite® resins from Huntsman, Beckopox® from Allnex, and VO RA FORCE® resins from Dow Chemical Company.

[0102] The various fragments of the siloxane chains specified in the formulas can be statistically distributed. Statistical distributions can be block-based with any number of blocks and any sequence, or subject to a randomized distribution; they can also be alternating or form a gradient across the chain; in particular, they can also form all mixed forms.

[0103] The index numbers and value ranges presented here can be understood as mean values ​​of the possible statistical distribution of the actual existing structures and / or their combinations. This also applies to structural formulas that are reproduced exactly as such.

[0104] In the context of this invention, the term "poly" encompasses not only compounds with at least three repeating units of one or more monomers in the molecule, but also, in particular, compositions of compounds that exhibit a molecular weight distribution and have an average molecular weight of at least 200 g / mol. This definition takes into account the fact that, in the relevant field of technology, it is common practice to refer to such compounds as polymers, even if they do not appear to meet a polymer definition analogous to OECD or REACH directives.

[0105] Unless otherwise stated, percentages are given as weight percentages.

[0106] If measured values ​​are given below, these measurements were carried out under standard conditions (25 °C and 1013 mbar), unless otherwise stated.

[0107] Unless otherwise stated, where average values ​​are given below, they are weight averages.

[0108] Polyethersulfone and polyamide-imide resins are preferably used as matrix-forming polymers. Commercially available examples include Ultrason® E 2020 P and RESISTHERM™ AI 336 L.

[0109] Preferably, fillers selected from the group consisting of precipitated silica, magnesium silicate, barium sulfate, quartz-free muscovite mica, aluminum silicate hydrate, and / or heat-stable pigments, e.g., spinel, rutile, or oxide pigments and mixtures thereof, can be added to the coating composition. Heat-stable pigments are preferred. Precipitated silica without a release agent coating is particularly preferred.

[0110] To produce the coating, the silica, treated with a release agent, is dispersed or mixed in the matrix-forming polymer and, if desired, with the filler. Uniform mixing between the silica-treated polymer and the filler is preferably achieved using a bead mill.

[0111] Advantageously, the mixture has a flowable consistency before and after milling and preferably has a viscosity of 10 to 1500 mPas, preferably of 10 to 800 mPas, particularly preferably of 50 to 250 mPas, as measured according to DIN 53019-2.

[0112] To achieve a flowable consistency or the viscosity described above, a solvent may be added to the coating composition described above. Commercially available solvents may be used. Advantageously, the solvent is selected from the group consisting of esters, aromatics, glycol esters, ketones, and mixtures thereof. Butyl acetate is most preferred for adjusting the consistency of the mixture or the viscosity described above.

[0113] Preferably, the coating composition according to the invention consists of:

[0114] 1.0 - 27.0 wt.%, preferably 7.0 - 22.0 wt.% silica coated with at least one release agent;

[0115] 10.0 - 50.0 wt.%, preferably 20.0 - 40.0 wt.% matrix-forming polymer; optionally up to 5.0 - 60.0 wt.%, preferably 20.0 - 30.0 wt.% solvent; and optionally 1.0 to 15.0 wt.%, preferably 3.0 - 10.0 wt.% filler, based on the coating composition.

[0116] Preferably, the weight ratio of silicas to release agents for application is freely selectable.

[0117] In a particularly advantageous embodiment, the silica in the coating composition according to the invention is preferably mixed with the release agent in a weight ratio of 1:3 to 3:1. The higher the concentration of the silica with the release agent, the better the non-stick effect. Preferably, the silica is mixed with the release agent in a weight ratio of 3:1, and even more preferably in a ratio of 2:1. At the above-mentioned mixing ratios, the silica is readily incorporated into the matrix polymer. After milling / mixing with the bead mill, the resulting mixture is free-flowing and has the desired viscosity described above.

[0118] Due to its advantageous properties, the coating composition according to the invention is used to produce a non-stick coating.

[0119] The invention therefore relates in a further aspect to a non-stick coating which comprises the coating composition according to the invention or is produced from the coating composition according to the invention.

[0120] Surprisingly, a non-stick coating produced in this way is characterized by improved non-stick properties; that is, no foreign materials, such as those present during food preparation, adhere to the coating, and the coating is easy to clean. Furthermore, a non-stick coating produced in this way exhibits increased mechanical strength, i.e., increased scratch resistance and / or increased abrasion resistance.

[0121] Despite improved non-stick properties, the non-stick coating produced from the coating composition according to the invention exhibits good adhesion to the surface of substrates such as metal, glass or ceramic.

[0122] Due to the advantageous properties described above, the coating composition according to the invention is suitable for coating cookware and bakeware so that food or baked goods do not stick to the cookware and can be more easily removed from the surface of the cookware. Due to its improved mechanical properties, the coating made from the coating composition according to the invention is less sensitive to scratching or abrasion.

[0123] The coating is applied to the surface of a substrate using known methods for producing non-stick coatings, for example, a high-pressure spraying process. The coating can be cured at a temperature of 250 to 300 °C.

[0124] The invention therefore relates in a further aspect to cookware for cooking, frying and / or baking, which includes the non-stick coating according to the invention, which is made from the coating composition according to the invention.

[0125] In another aspect, the present invention relates to a method for producing a coating composition, comprising the following steps:

[0126] (a) Applying at least one silica to at least one separating agent, optionally in the presence of a solvent;

[0127] (b) optionally separating and evaporating the solvent;

[0128] (c) Drying the treated silica to obtain silica treated with the separating agent as component A;

[0129] (d) Mixing the applied silica with at least one matrix-forming polymer as component B;

[0130] (e) Optionally, adjusting the viscosity of the mixture with a solvent. To produce the coating composition, in a first step of the process, the silica is reacted with the release agent.

[0131] The silica is optionally dispersed in a solvent, preferably a volatile solvent at room temperature. In a further step, the release agent is added to this dispersion. If necessary, the solvent can be removed thermally, depending on the solvent used.

[0132] This mixture is then dried at a temperature in the range of 150°C to 230°C, preferably 180°C - 210°C.

[0133] In a further step, the silica, which has been treated with the release agent, is mixed with a matrix-forming polymer to produce the coating composition. This mixing is carried out using known process techniques.

[0134] Preferably, the mixture of applied silica with the matrix polymer is milled in a bead mill to obtain both a fine grain size of the silica particles and a uniform and even distribution of the applied silica particles in the matrix.

[0135] To adjust the viscosity of the mixture of applied silica and matrix polymer, a solvent is added to the mixture, while maintaining the coating composition according to the invention. The solvent is preferably selected from the group consisting of esters, aromatics, ketones, glycol esters, and mixtures thereof. Butyl acetate is most preferably used to adjust the viscosity.

[0136] Regarding the silica, the release agent, the matrix-forming polymer and their preferred embodiments, reference is made to the detailed description of these components in connection with the coating composition according to the invention.

[0137] In a particularly advantageous embodiment, the silica in the coating composition according to the invention is mixed with the release agent in a weight ratio of 1:3 to 3:1. The higher the concentration of the silica with the release agent, the better the non-stick effect. Preferably, the silica is mixed with the release agent in a weight ratio of 3:1, and even more preferably in a ratio of 2:1. At the aforementioned mixing ratios, the silica is readily incorporated into the matrix polymer. After milling / mixing with the bead mill, the resulting mixture is free-flowing and has the desired viscosity described above.

[0138] In a preferred embodiment of the process, a filler is added in step (d) to the mixture of applied silica and matrix polymer to improve the mechanical properties. Such fillers are described above.

[0139] Advantageously, the coating composition produced according to the inventive method, consisting of applied silica and polymer and optionally filler, has a viscosity of 10 to 1500 mPas, preferably a viscosity of 10 to 800 mPas, particularly preferably 50 to 250 mPas, as measured according to DIN 53019-2.

[0140] Due to the advantageous properties described above, the coating composition according to the invention is suitable for coating cookware and bakeware so that food or baked goods do not stick to the cookware, roasting utensils, and bakeware and can be more easily removed from the surface. The improved non-stick properties also allow for better cleaning of the cookware, roasting utensils, and bakeware. Due to its improved mechanical properties, the coating made from the coating composition according to the invention is less susceptible to scratching or abrasion.

[0141] The present invention therefore relates in a further aspect to the use of the coating composition according to the invention for coating cookware for cooking, frying and / or baking.

[0142] Finally, the present invention relates to the use of a silica coated with a release agent to improve the non-stick properties of a non-stick coating.

[0143] Surprisingly, it has been found that such particles, treated with a release agent, can significantly improve the non-stick properties of a non-stick coating. The non-stick properties are comparable to those of Teflon coatings. Therefore, the invention also relates to silica treated with at least one release agent, produced according to the first process step of the invention, optionally after removal of the solvent, and drying.

[0144] The present invention is described in more detail in the following examples. These examples serve to illustrate the invention without limiting it.

[0145] Examples:

[0146] 1. Production of silicas treated with a separating agent

[0147] Table 1.1 shows the recipes for the production of the silicas 1a - 1h according to the invention.

[0148] Table 1.1 : 1.1 The production of the silicone oils according to formula (I) for items 3a and 3d is well known to those skilled in the art, in particular also known from the teaching of EP 1 072 660 A2, Example 2. Silicone oils were used which had an ethoxy content of <5 wt.% and the following structure:

[0149] Ma M a1 Db D b1 Tc Qd with

[0150] M = (R 1 3SiOi / 2)

[0151] M' = (R 2 R 1 2SiOi / 2)

[0152] D = (R 1 2SiO 2 / 2 )

[0153] D' = (R 2 R 1 SiO 2 / 2 )

[0154] T = (R 3 SiO3 / 2)

[0155] Q = (SiO4 / 2) a = 0 to 2 a1 = 0 to 2 b = 50 to 150 b1 = 0 c = 0 to 3 d = 0

[0156] R 1 = Methyl

[0157] R 3 = Methyl or phenyl with the following physicochemical characteristics:

[0158] Viscosity (25°C): 41 mPas, determined according to DIN standard 53019

[0159] Solid at 105°C, 30 min: 96.8 wt.%

[0160] Density (25°C): 0.984, determined according to DIN 51757

[0161] Refractive index (25°C): 1.4185, determined according to DIN 51423

[0162] The production of the silicone oil for item 3c is also known to those skilled in the art from the teaching of EP 1 072 660 A2, Example 1, wherein the silicone oil according to formula (I) has c = 0 and b = <50. 1.2 General description of the production

[0163] First, the solvent was added to the silica (items 2a-2d), and then the silicone oil (items 3a-3f) was added with stirring according to the instructions in Table 1.1. This mixture was homogenized for 30 minutes with a dispersant (LC 75; Getzmann) at 1500 rpm. The solvent was evaporated at room temperature for 24 hours, and then the mixture was dried for 1 hour at 180°C in a convection oven. A white powder (items 1a-1h) was obtained.

[0164] Table 1.2 shows the carbon content, determined with LECO according to ISO 3262-19, and the tapped density, determined according to DIN ISO 787-11:1995, of the silicas according to the invention.

[0165] Table 1.2:

[0166] 2. Production of coating compositions

[0167] For testing the non-stick properties, the coating compositions according to the invention (AB1 - AB3, AB6 - AB16) as well as the comparison compositions VG1 and VG2 were produced.

[0168] 2.1 Production of the non-stick coating compositions according to the invention (AB 1-3 & 6-8)

[0169] According to the information in Table 2.1, items 1, 4, and 5 were first mixed, then items 2 and 3 were added portionwise while stirring. The mixture was then milled using glass beads to a particle size of < 15 pm. The glass beads were then removed, and item 6 was added while stirring (at 2500 rpm for 15 minutes). Butyl acetate (item 7) was used to adjust the viscosity. Table 2.1

[0170] 2.2 Production of non-stick coating compositions as

[0171] Comparison examples (VG 1-1 - VG 1-3) Table 2.2

[0172] According to the information in Table 2.2, items 1, 4, and 5 were first mixed, then items 2 and 3 were added portionwise while stirring. The mixture was then milled using glass beads to a particle size of < 15 pm. The glass beads were then removed, and item 6 was added while stirring (at 2500 rpm for 15 minutes). Butyl acetate (item 7) was used to adjust the viscosity. 2.3 Production of non-stick coating compositions as comparative examples VG 2-1, VG 2-3, VG 2-6, and VG 2-7 Table 2.3 According to the instructions in Table 2.3, items 1, 5, and 6 were first mixed, then items 2, 3, and 4 were added portionwise while stirring. The mixture was then milled using glass beads to a particle size of < 15 pm. The glass beads were then removed, and item 7 was added while stirring (at 2500 rpm for 15 minutes). Butyl acetate (item 8) was used to adjust the viscosity.

[0173] 2.4. Production of a non-stick coating with PTFE as a comparative example VG 3

[0174] Table 2.4

[0175] According to the information in Table 2.4, items 1, 2, 3, and 4 were mixed. Water (item 5) was used to adjust the run-off time to approximately 20 seconds according to DIN 53211.

[0176] 3 Application-related studies

[0177] 3.1 Production of the test panel blanks

[0178] 3.1.1 Production of the test panel blanks with the coating composition according to the invention and comparative examples

[0179] Test panels were produced to test the non-stick properties. Pure aluminum plates AI 99.5 (Krüppel, Krefeld) measuring 210 x 150 x 5 mm were used. These test panels were sandblasted with corundum No. 150, grain size 63-150 µm (MHG GmbH, Düsseldorf) at 3.5 bar using an SMG 50 / 1 blasting unit (MHG GmbH, Düsseldorf).

[0180] The non-stick coating compositions according to the invention (AB 1-3 & 6-16), comparative examples (VG 1-1 - VG 1-3), comparative examples VG 2-1, VG 2-3, VG 2-6 and VG 2-7 were applied to the test panel by high-pressure spraying using a SATAjet® 4000 B RP gun, nozzle: 1.4 mm, at an air pressure of 2 bar. The coated test panel was cured in a Carbolite PF SC 120 convection oven at 250°C for 45 minutes. The dry film thickness was 20-30 µm. The test panel was removed and cooled to room temperature.

[0181] 3.1.2 Production of the test panel blanks for comparison example VG3

[0182] Pure aluminum plates AI 99.5 (Krüppel, Krefeld) measuring 210 x 150 x 5 mm were used. These test panels were sandblasted with corundum No. 150, grain size 63-150 µm (MHG GmbH, Düsseldorf) at 3.5 bar using an SMG 50 / 1 blasting unit (MHG GmbH, Düsseldorf). The comparative sample VG3 was applied to the test panel using a SATAjet® 4000 B RP high-pressure spray gun with a 1.4 mm nozzle at 2 bar air pressure. The dry film thickness was 22-27 µm.

[0183] The coated test panel was first pre-dried in a Carbolite PF SC 120 convection oven at 250°C for 15 minutes. This was followed by the sintering step, which took place for 15 minutes at 380°C in a Nabertherm N 120 65 HA oven. The test panel was then removed and cooled to room temperature.

[0184] The coated test panel was used for the non-stick test.

[0185] The coated test panels were used for the non-stick test. 3.2 Non-stick test according to DIN EN 13834 - Annex C

[0186] 3.2.1 Preparation of a dough mixture

[0187] For the non-stick test, a dough mixture was prepared with the following recipe:

[0188] 1 egg (approx. 60 g)

[0189] 20 g flour

[0190] 20 g butter

[0191] 20 g granulated sugar

[0192] 3g baking powder Backin (Oetker)

[0193] The ingredients were mixed using a Krups 3 Mix 7000 mixer until a homogeneous dough was formed.

[0194] 3.2.2 General examination description

[0195] 100 g of dough mixture was spread on the surface of the coated test panel. The test panel was then placed in a preheated oven according to DIN EN 13834 - Annex C and baked at a temperature of 180°C + / - 15°C until the dough mixture no longer adhered to a clean, smooth, stainless steel knife blade. The test panel with the baked dough was removed from the oven and allowed to cool for 5 minutes. The baked dough was then turned over by inverting the test panel, if necessary by gently tapping the base.

[0196] The test panel was immersed for 10 seconds in 60 °C+ / -5 °C warm water containing household dishwashing liquid (Pril Original, Henkel AG & Co. KGaA) and washed with the soft side of a Scotch Brite sponge (3M; Art. No. 7100248036).

[0197] For the subsequent cycles, the test panel was rinsed with hot and then with cold water and dried.

[0198] The evaluation was based on the following scale:

[0199] 0: It is impossible to remove the food without destroying the coating.

[0200] 1: The food sticks and tears through the spatula.

[0201] 3: The food can be completely removed with the spatula and slight force. 4: The food comes off completely when lifted at the edge with the spatula. No change to the surface is observed after rinsing.

[0202] 5: The food detaches completely when the test plate is turned over. No change to the surface is observed after rinsing.

[0203] A non-stick effect is present if a score of 3 to 5 can be awarded. The results are shown in Table 3:

[0204] Table 3: As can be seen from Table 3, the coating AB1 - AB16 according to the invention exhibited excellent non-stick properties. These non-stick properties are comparable to those of the reference coating VG3. In comparison, all other reference examples showed significantly inferior non-stick properties. In particular, their non-stick properties decreased after the second test cycle until they were no longer present.

[0205] 3.3 Determination of compatibility

[0206] The compatibility of the particles from 1.1 with the silicone polyester from 2.1 was determined by measuring the gloss level of the cured coating.

[0207] To quantify gloss, measuring the reflected light component at a 60° angle has become established. To determine the gloss level, a print was made on black and white contrast card, and the gloss level was then measured at a 60° angle using a Haze-Gloss reflectometer from Byk-Gardner. The measured data (gloss unit = GU) are shown in Table 3.

[0208] 4. Estimation of the adhesive strength according to DIN ISO 2409

[0209] The same test panels were used as described in 3.1.1 and 3.1.2.

[0210] Table 4 The PTFE-containing coating VG3 exhibited poorer adhesion than the other coatings.

Claims

Patent claims 1. Coating composition, comprising - at least one silica compound coated with at least one separating agent, as component A, - at least one matrix-forming polymer as component B, - optionally at least one solvent and - optionally at least one filler.

2. Coating composition according to claim 1, characterized in that it is not organo-fluorine based.

3. Coating composition according to claim 1 or claim 2, wherein the silica is selected from the group consisting of precipitated silica and pyrogenic silica, and mixtures thereof.

4. Coating composition according to one of the preceding claims, wherein the silica has a specific surface area of ​​25 to 400 m² 2 / g has, preferably a specific surface area of ​​100 to 280 m² 2 / g, determined according to DIN 9277:2014 and / or wherein the tapped density of the silica is in the range of up to 400 g / L, preferably from 30 to 300 g / L, determined according to DIN ISO 787-11:1995.

5. Coating composition according to one of claims 1 to 4, characterized in that the release agent is a silicone oil, preferably compounds according to formula (I) or mixtures thereof: M a M'ai D b D'bi T c Qd formula (I) with M = (R 1 3SiOi / 2) M' = (R 2 R 1 2SiOi / 2) D = (R 1 2SiO 2 / 2 ) D' = (R 2 R 1 SiO 2 / 2 ) T = (R 3 SiO 3 / 2 ) Q = (SiO4 / 2) a = 0 to 40, preferably 0 to 12, a1 = 0 to 40, preferably 0 to 20, b = 5 to 1000, preferably 5 to 800, in particular 5 to 200, b1 = 0 to 30, preferably 1 to 15, c = 0 to 40, preferably 0 to 20, in particular 0 to 10, d = 0 to 20, preferably 0 to 12, in particular 0 to 5, R 1 = independently identical or different linear or branched, optionally aromatic hydrocarbon residues with 1 to 30 carbon atoms, preferably methyl, ethyl, propyl, aralkyl and / or aromatic residue, dodecyl or hexadecyl, in particular methyl and phenyl, R 2 = independent of each other identical or different organic polyether, hydride, hydroxy, amine, carboxy, alkoxy, epoxy, acetoxy, alkylalkoxysilylalkyl or alkoxysilylalkyl residues, R 3 = R 1 or R 2 , preferably methyl, ethyl, propyl, aralkyl and / or aromatic residues, or alkoxy residues, in particular methyl and phenyl residues.

6. Coating composition according to any one of claims 1 to 5, wherein the matrix-forming polymer is selected from the group consisting of silicone resins, silicone polyester resin, polyethersulfone and polyamide-imide resin.

7. Coating composition according to any one of claims 1 to 6, wherein the filler is selected from the group consisting of precipitated silica, magnesium silicate, barium sulfate, quartz-free muscovite mica, aluminum silicate hydrate, and / or pigments, and mixtures thereof.

8. Coating composition according to any one of claims 1 to 6, wherein the coating composition has a viscosity of 10 to 1500 mPas, preferably a viscosity of 10 to 800 mPas, particularly preferably 50 to 250 mPas, measured according to DIN 53019-2.

9. Non-stick coating, manufactured from the coating composition according to any one of claims 1 to 8.

10. Article, preferably cookware or other household and utility item, with a surface provided with a non-stick coating according to claim 9.

11. Method for producing a coating composition comprising the following steps: (a) Applying at least one silica to at least one separating agent, optionally in the presence of a solvent, (b) optionally separating and evaporating the solvent, (c) Drying the treated silica to obtain silica treated with the separating agent as component A, (d) Mixing the applied silica with at least one matrix-forming polymer as component B, and (e) optionally adjusting the viscosity of the mixture with a solvent.

12. The method of claim 11, wherein the silica is selected from the group consisting of precipitated silica, pyrogenic silica and mixtures thereof.

13. Method according to one of claims 11 - 12, wherein the separating agent is selected from the group consisting of a compound according to formula (I).

14. Method according to claim 11, wherein the silica is mixed with the separating agent in a weight ratio of 1 : 3 to 3 : 1, preferably wherein the silica is mixed with the separating agent in a ratio of 2 :

1.

15. A method according to any one of claims 11 to 14, further comprising the step of adding a filler to the mixture in step (d).

16. Method according to any one of claims 11 to 15, wherein the coating composition has a viscosity of 10 to 1500 mPas, preferably a viscosity of 10 to 800 mPas, particularly preferably 50 to 250 mPas, measured according to DIN 53019-2.

17. Silica treated with at least one separating agent according to one of claims 11 - 14.

18. Use of the coating composition according to any one of claims 1 to 8 for coating articles, preferably cookware or other household and consumer goods, with a surface having a non-stick property.

19. Use of a silica coated with a release agent to improve the non-stick properties of a non-stick coating.

Images