Matt powder coatings for producing textured surfaces

Abstract

The invention relates to the use of polymethylpentene in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing same, as structuring agent in a matt powder coating mixture or the precursor mixture thereof to produce surface textures.

Description

[0001] TITLE

[0002] POWDER MATT COATINGS FOR CREATING TEXTURED SURFACES

[0003] TECHNICAL FIELD

[0004] The present invention relates to structuring agents for powder coating mixtures, uses of such structuring agents, powder coating mixtures with such structuring agents, processes for producing such powder coating mixtures with these structuring agents, processes for producing painted surfaces with such powder coating mixtures and further objects in this context.

[0005] STATE OF THE ART

[0006] Powder coatings are thermosetting or thermosetting coating materials used primarily, but not exclusively, in metal coatings. Their basic composition typically includes a polymeric binder, pigments for color, additives to influence the surface appearance and properties, processability, and other technical properties, as well as fillers. The roughly pre-blended mixtures of the aforementioned components are processed in an extrusion process (compounding) at elevated temperatures and dispersed under the influence of shear forces. This creates a flowable mass, which is then cooled and solidifies. This extrudate can be processed into powder with the desired particle size distribution using various grinding techniques. Classifier mills are typically used for this purpose.The particle size of powder coating grains typically ranges from just under one micrometer to approximately 200 micrometers. The particle size distribution is typically broad, with the average grain size usually ranging between 20 and 60 micrometers.

[0007] After electrostatic application to a desired substrate, e.g., using powder coating guns, the parts are heated, which melts the powder coating particles at least enough to form a continuous, preferably pore-free coating. In the case of thermosetting coatings, a chemical reaction takes place in the binder due to the simultaneous presence of a hardener component, which crosslinks the paint film and thus enables highly chemically resistant coatings, depending on the crosslinking density. These crosslinking reactions typically occur at temperatures in the range of 80–250°C.For thermoplastic powder coatings, this temperature range is broader and in special cases can even be several hundred degrees Celsius, since the process window usually has to be well above the melting temperature in order to achieve sufficient flowability of the powder and thus a sufficient surface quality.

[0008] To diversify the surface appearance, powder coatings can also contain special additives that influence the gloss or texture of the surface.

[0009] Popular types of surface textures are so-called coarse structures, wrinkle or fine structures.

[0010] Coarse structures are often created by incorporating small amounts of additives into the coating formulation. These additives, such as cellulose acetate butyrates or silicone derivatives, are released to the surface during the melting process and inhomogeneously alter its surface tension. This results in wavy, but not sandy, surfaces.

[0011] So-called wrinkle surfaces are created using special hardeners and catalysts (e.g., glycoluril hardeners activated by special capped sulfonic acid catalysts). They are best compared to finely crumpled paper, but differ significantly from sand-like fine structures.

[0012] The particularly popular surface type of fine structures, comparable to a sand-like surface in varying degrees of fineness, haptically soft or roughness, represents a specialty in the coatings industry. The high popularity of these surfaces in the powder coating sector can be explained by the originally rather poor flow properties of powder coatings, but has since developed further and established itself in a controlled manner.

[0013] According to the state of the art, these fine structures are created using fine-particulate PTFE or similar halogenated plastics. These can be combined with other additives such as rheology-modifying materials (e.g., fumed silica, fumed aluminum oxide, phyllosilicates, or talc). The use of these substances significantly alters the flow behavior of the coating in the molten state, and the viscosity increases significantly even with relatively small addition quantities, allowing the desired surface textures to develop. However, the latter materials merely support the PTFE structuring agent and can improve its efficiency. The small addition quantities of PTFE allow for a high degree of formulation flexibility; among other things, the binder quantities can be varied within a wide range.This allows for targeted adaptation of formulations with regard to the mechanical properties and UV resistance of the coatings, largely independent of the desired fine structure. Low binder contents (or the use of additives that require low binder contents) often lead to low application efficiency. This is due to the fact that lower binder contents lead to higher densities and poorer electrostatic chargeability.

[0014] The above-mentioned relationships demonstrate the importance of low application quantities of the agents used for texturing purposes (and their high effectiveness) for the powder coating industry. To date, only PTFE and similar halogenated, high-melting polymers have established themselves in the powder coating sector. Other polymers with comparable structural characteristics and similar effectiveness (use of a maximum of a few percent by volume) were previously unknown for the fine structuring of powder coatings.

[0015] CN-A-103773127 discloses a matte, reflective radiation shielding coating. The matte radiation shielding coating contains the following raw materials in parts by weight: 1 to 100 parts polyethylene E3099, 1 to 2 parts polyvinyl butyral, 3 to 4 parts hydrolytic polymaleic anhydride, 2 to 3 parts sodium silicate, 0.8 to 1 part 3-aminopropyltrimethoxysilane, 1 to 2 parts casein, 10 to 12 parts heavy calcium carbonate, 0.4 to 1 part anthracene oil, 4 to 6 parts tricresyl phosphate, 2 to 3 parts poly-4-methyl-1-pentene, 1 to 2 parts potassium sodium tartrate, 1 to 2 parts polysorbate 80, 2 to 4 parts aluminum nitride, and 6 to 9 parts modifier. The radiation shielding coating has high extinction performance, high wear performance, excellent surface resistance, high mechanical strength, excellent radiation performance and long service life.

[0016] CN-A-103509446 discloses a nanometer polyester powder coating consisting of the following raw materials in parts by weight: 40-50 parts unsaturated polyester resin, 2-3 parts nanometer diatomaceous earth, 4-6 parts silicon oxide, 1-3 parts nanometer zinc oxide, 2.0-2.5 parts beta-hydroxyalkylamide SA552, 2.5-3.5 parts urotropine, 2-4 parts acrylic acid ester filler, 2-3 parts butyltin trioctanate, 1-2 parts 1H-benzotriazole, 1-2 parts poly(4-methyl-1-pentene), and 10-20 parts of a composite filler. The powder coating exhibits good leveling properties, uniform color, high UV resistance, good impact resistance, long-lasting aging resistance, stability, and a long service life.

[0017] EP-A-0456929 discloses a semi-transparent resin container with a pearl gray luster made from thermoplastic resins prepared by adding 0.01 to 0.9 wt.% polymethylpentene to 99.99 wt.% polyester resins. The thermoplastic resins are subjected to biaxially oriented blow molding after preform molding. In this way, the pearl gray luster of a container can be enhanced, and the strength of the container can also be improved.

[0018] CN-A-101602905 relates to a manufacturing process for a solvent-free polyacrylate smoothing agent. The manufacturing process comprises the following steps: 10-30 wt.% of a solvent-free polyacrylic acid flow agent is used as a prepreg, then 70-90 wt.% of a mixed monomer capable of polymerization is dropped into it, and the solvent-free polyacrylate flow agent is obtained by conducting a radical polymerization reaction at 100-170°C. Compared with the prior art, the invention has the characteristics of low temperature, normal pressure, solvent-free operation, waste reduction, and the like, and conforms to the trend of environmental protection. The produced polyacrylate flow agent can be used for flow-leveling and shrink-free hole filling of solvent-based or solvent-free systems with powder bodies.

[0019] PRESENTATION OF THE INVENTION

[0020] The present invention describes the use of halogen-free polymers as structuring agents with the aim of creating sand-like surface textures in powder coatings that are visually, mechanically, haptically, and technically comparable to or even superior to those produced with PTFE and other halogenated polymers. For economic and / or ecological reasons, the halogenated structuring agents used in the prior art are problematic and are likely to be severely restricted or even banned for use in powder coating mixtures in the medium term. Accordingly, there is a great need for alternatives.

[0021] In the course of extensive tests with a wide variety of polymers, in particular those based on polyolefins, it has unexpectedly emerged that only the polymethylpentene system is capable of replacing, in an equivalent or even improved manner, the structure agents based on halogenated hydrocarbons, in particular those based on PTFE, which are known in the state of the art.

[0022] The present invention describes the use of polymethylpentene, its copolymers, derivatives, and mixtures thereof for the production of powder coatings for creating sand-like surface textures of varying intensity. For this purpose, polymethylpentene is incorporated in particulate form in amounts between 0.01% and 10% into powder coating precursor mixtures and processed by extrusion. Polymethylpentene, its copolymers, or structurally related polymers are, if appropriate, converted into a finely divided form (granular or fibrous) by suitable processes. The particle size of polymethylpentene, its copolymers, or structurally related polymers for this purpose normally ranges between 0.1 and 500 μm, preferably between 2 and 100 μm.By introducing these polymer particles, the rheology of the paint changes significantly and it is enabled to form finely textured surfaces even with small addition quantities in the melting and crosslinking process.

[0023] Similar to the use of PTFE as a structuring agent, the particle size distribution of polymethylpentene is also important. Adjusting the particle size distribution of commercially available polymethylpentenes to the desired size (e.g., TPX RT18, Mitsui, to a median particle size of approximately 10 pm) can be achieved using the following methods:

[0024] 1. Dissolving the polymer in suitable solvents at temperatures below or above the glass transition temperature of the polymer and then precipitating the polymer by introducing another solvent or cooling or evaporating the solvent. Organic solvents such as methanol, ethanol, propanol, butanol, pentane, hexane, heptane, octane, cyclopentane, cyclohexane, THF, benzene, toluene, xylenes or mixtures thereof are preferably used. The polymer is preferably dissolved at temperatures above its glass transition temperature and below the boiling temperature of the solvent and reprecipitated at temperatures below the boiling temperature of the solvent. Inorganic or organic crystallization aids (e.g. as crystallization seeds) can be used for this purpose. For example, the polymer itself or calcium fluoride or other inorganic solids can be used for this purpose.

[0025] 2. Grinding using knife mills below or above the glass transition temperature of the polymer. Grinding is preferably carried out at temperatures above -78 °C. The grinding process can be carried out with or without the use of grinding aids. Examples of grinding aids include calcium fluoride or other inorganic solids.

[0026] 3. Grinding using high-performance mills at temperatures below or above the glass transition temperature of the polymer. Cutting, classifying, jet, or pin mills are preferred. The grinding temperature is ideally above -195 °C and below 79 °C. The grinding process can be carried out with or without the use of grinding aids. Calcium fluoride or other inorganic solids, for example, can be used as grinding aids. 4. Grinding using ball, vibratory, or drum mills at temperatures below the glass transition temperature of the polymer. The grinding process is preferably carried out at temperatures between -195 °C and -78 °C. The grinding process can be assisted by the use of grinding aids such as steel balls.

[0027] 5. A combination of processes 1-4, where process 1 can be carried out before or after a grinding process.

[0028] 6. A combination of methods 1-4 where method 1 can be used repeatedly.

[0029] A cryogenic grinding technique (liquid nitrogen) is particularly advantageous in the pure state of the polymethylpentene polymer to obtain it fine enough.

[0030] What can be particularly helpful with regard to grinding is to pre-fill the polymethylpentene polymer with a suitable filler (e.g., with at least one filler selected from the following group: aluminum trihydrate, aluminum oxide, barium sulfate, calcium carbonate, zinc oxide, borosilicate glass, silicon dioxide, phyllosilicates, talc, fumed silica, or fumed alumina). This makes the polymethylpentene polymer more brittle and less impact-resistant, making it easier to grind. For filling, the polymethylpentene polymer can be melted in a plastic extruder and compounded with filler.

[0031] All of the above-mentioned processes can be carried out below or above atmospheric pressure. Depending on the process, a slight overpressure or negative pressure is ideally used to improve work safety.

[0032] According to a first aspect of the present invention, it relates to the use of polymethylpentene, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, as a structuring agent in a powder coating mixture or its precursor mixture for producing surface textures.

[0033] Polymethylpentene is preferably used for the production of powder coatings that do not contain any additives or additive mixtures to specifically increase thermal stability or thermal conductivity. Accordingly, polymethylpentene is preferably used for the production of powder coatings that do not contain any (particularly non-pigment) additives or additive mixtures that have been calcined prior to addition to the powder coating, i.e., preferably not subjected to treatment at a temperature of at least 500°C for at least 1 hour.

[0034] Furthermore, the powder coating mixtures in which the polymethylpentene is used preferably do not contain any (high-temperature stable and preferably calcined) additives selected from the following group: (nano-)diatomite, borate, agalmatolite, latent, wollastonite, iron ore slag, bone meal, alum, jade powder, or a combination of these preferably powdered additives.

[0035] Furthermore, the powder coating mixtures in which the polymethylpentene is used preferably do not contain any additives selected from the following group: urotropin, eucalyptus oil, ground iron ore slag, hydrolyzed polymaleic anhydride, aminopropyltrimethoxysilane, casein, carbolineum, tritolyl phosphate, Seignette salt, polysorbate, in particular polysorbate 80, aluminum nitride, or a combination.

[0036] When reference is made to polymethylpentene without further specification below, this means polymethylpentene in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these.

[0037] The polymethylpentene preferably has a melting point of at least 210 °C, particularly preferably at least 220 °C, particularly preferably in the range of 220-240 °C (each determined using the DSC method according to ASTM D3418).

[0038] Alternatively or additionally, the polymethylpentene preferably has a density in the range of 800-850 kg / m3 (determined according to DIN EN ISO 1183).

[0039] Alternatively or additionally, the polymethylpentene preferably has a molecular weight in the range of 50,000-2,000,000, particularly preferably in the range of 200,000-700,000 (determined according to ISO 16014-3).

[0040] Alternatively or additionally, the polymethylpentene preferably has a surface tension in the range of 20-30 mN / m (determined according to ISO 1409).

[0041] Alternatively or additionally, the polymethylpentene preferably has a glass transition point in the range of 10-40 °C, particularly preferably in the range of 20-30 °C (determined according to ISO 11357-2).

[0042] The proposed use is preferably characterized in that the polymethylpentene is a polymethylpentene copolymer copolymerized with one or more of ethylene, propylene, butene, pentene, hexene, heptene, octene, nonene and decene, preferably propylene, wherein the content of 4-methyl-1-pentene in the polymethylpentene copolymer is preferably at least 60 wt% or at least 80 wt% or 95-100 wt%.

[0043] The proposed use is preferably alternatively characterized in that the polymethylpentene is a polymethylpentene copolymer of 4-methyl-1-pentene and a C2-C20 monomer, wherein the C2-C20 monomer is different from 4-methyl-1-pentene, wherein the content of 4-methyl-1-pentene in the polymethylpentene copolymer is preferably at least 80 wt% or 95-100 wt%. The C2-C20 monomer is preferably selected from ethene, propene, butene, butadiene, pentadiene, hexadiene, styrene, methylstyrene, ethylstyrene, their cyclic and halogenated forms, derived alcohols, ketones, aldehydes, carboxylic acids, esters, amides, imides, anhydrides, pyrrolidones, nitro compounds and salts thereof, or a combination of such co-building blocks.

[0044] The polymethylpentene is preferably present as pure polymethylpentene or as a polymethylpentene copolymer or polymethylpentene derivative in a mixture with another polymer, preferably with a polyolefin different from polymethylpentene, in particular polypropylene, wherein the proportion of polymethylpentene in this mixture is preferably at least 50 percent by weight, preferably at least 80 percent by weight, particularly preferably in the range of 90-100 or 95-100 percent by weight.

[0045] The polymethylpentene can also be present as a polymethylpentene derivative in the form of a grafted polymethylpentene.

[0046] A further preferred embodiment is characterized in that the polymethylpentene in the powder coating mixture or its precursor mixture is present with a particle size median in the range of 0.1 - 500 pm, preferably between 2 - 100 pm or in the range of 5-40 pm, preferably in the range of 10-30 pm.

[0047] A preferred embodiment is characterized in that the surface texture is a surface with a surface roughness (Rz) in the range of 1-100 pm, particularly preferably in the range of 2-50 pm and / or with a mean roughness value (Ra) in the range of 0.1 - 20 pm, particularly preferably in the range of 0.2 - 10 pm.

[0048] Another preferred embodiment is characterized in that the surface texture has a gloss at a measuring angle of 60° in the range of 1-50, preferably in the range of 10-40.

[0049] Furthermore, the present invention relates to a powder coating mixture or its precursor mixture for producing surface textures, characterized in that the powder coating mixture contains polymethylpentene as structuring agent, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, preferably in a weight fraction in the range of 0.01-10%, preferably in the range of 0.1-5%.

[0050] This can be a thermoplastic or a thermosetting powder coating mixture.

[0051] Preferably, these are powder coatings that do not contain any additives or additive mixtures specifically designed to increase thermal stability or thermal conductivity. Preferably, these are powder coatings that do not contain any additives or additive mixtures that have been calcined prior to addition to the powder coating, i.e., preferably, that have not been subjected to treatment at a temperature of at least 500°C for at least 1 hour.

[0052] Furthermore, the powder coating mixtures preferably do not contain any (high-temperature stable and preferably calcined) additives selected from the following group: (nano-)diatomite, borate, agalmatolite, latent, wollastonite, iron ore slag, bone meal, alum, jade powder, or a combination of these preferably powdered additives.

[0053] Furthermore, the powder coating mixtures preferably do not contain any additives selected from the following group: urotropin, eucalyptus oil, ground iron ore slag, hydrolyzed polymaleic anhydride, aminopropyltrimethoxysilane, casein, carbolineum, tritolyl phosphate, Seignette salt, polysorbate, in particular polysorbate 80, aluminum nitride, or a combination.

[0054] Preferably, it is a thermosetting powder coating mixture, wherein the powder coating mixture is based on epoxy resins, on polyester resins, including polyester resins with glycidylic hardener, polyester resins with hydroxyalkylamide hardener, polyester resins with isocyanate hardener, on acrylate resins, or on a mixture of one or more of these resins.

[0055] The polymethylpentene is present in the powder coating mixture or its precursor mixture preferably with a median particle size in the range of 0.1 - 500 pm, preferably between 2 - 100 pm or in the range of 5-40 pm, preferably in the range of 10-30 pm.

[0056] Furthermore, the present invention relates to a process for producing such a powder coating mixture, characterized in that polymethylpentene, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, is mixed as a structuring agent, preferably in a weight proportion in the range of 0.01-10%, preferably in the range of 0.1-5% with further components, in particular at least one binder and at least one hardener and optionally further fillers, additives and dyes or pigments, to form a precursor mixture and then extruded, followed by comminution of the extrudate to form an application-ready powder coating mixture, preferably in a mill, particularly preferably at a temperature below room temperature, or at a temperature of less than -100 °C, preferably using a mill.

[0057] The process can be characterized in that the structuring agent polymethylpentene is brought to a suitable particle size, in particular a particle size median in the range of 0.1 - 500 pm, preferably between 2 - 100 pm or in the range of 5-80 pm or 5-40 pm, preferably in the range of 10-30 pm, before addition, preferably by dissolving the polymethylpentene in a solvent and subsequently precipitating it, and / or by comminution, in particular by grinding in a mill, optionally multi-stage grinding, optionally followed by sieve separation.An organic solvent, particularly preferably selected from the group or a mixture thereof, can be used as the solvent, wherein the polymethylpentene is preferably dissolved at temperatures above its glass transition temperature but below the boiling temperature of the solvent and precipitated at temperatures below the boiling temperature of the solvent, wherein crystallization aids can be used.

[0058] The mill used may be a knife mill, a cutting mill, a classifier mill, a pin mill, a ball mill, a vibrating mill, or a drum mill or a sequence of the same or different ones of these mills, wherein the grinding temperature is preferably below room temperature and / or below the glass transition temperature of the polymethylpentene.

[0059] Furthermore, the present invention relates to a use of such a powder coating mixture for producing a coating, in particular on a metallic surface, wherein the coating is a surface with a surface roughness (Rz) in the range of 1-100 pm, particularly preferably in the range of 2-50 pm and a mean roughness (Ra) in the range of 0.1 - 20 pm, particularly preferably in the range of 0.2 - 10 pm, and / or wherein the surface texture has a gloss at a measuring angle of 60° in the range of 1-50, preferably in the range of 10-40.

[0060] Last but not least, the invention relates to a method for producing a coated surface with surface texture using such a powder coating mixture, in which the powder coating mixture is applied electrostatically to a substrate and subsequently heated, preferably by convection, induction, or infrared heating, whereby the powder coating grains melt and form a substantially continuous, preferably pore-free coating layer. Chemical crosslinking preferably occurs, and a thermosetting layer forms. Crosslinking can be thermally induced or triggered with the aid of UV or X-ray radiation, or electron beams, and crosslinking times preferably range between 3-5 minutes and 120 minutes, preferably between 1-30 minutes, preferably at temperatures between 80-250°C, preferably between 120-230°C.The surface texture is preferably a surface with a surface roughness (Rz) in the range of 1-100 pm, particularly preferably in the range of 2-50 pm and / or with an average roughness (Ra) in the range of 0.1 - 20 pm, particularly preferably in the range of 0.2 - 10 pm, and / or wherein the surface texture has a gloss at a measuring angle of 60° in the range of 1-50, preferably in the range of 10-40.

[0061] Further embodiments are specified in the dependent claims.

[0062] BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Preferred embodiments of the invention are described below with reference to the figures, which are for illustrative purposes only and are not to be interpreted in a restrictive manner. The figures show:

[0064] Fig. 1 a finely textured surface created using PTFE structuring agents;

[0065] Fig. 2 a finely textured surface produced using polymethylpentene structuring agent

[0066] (TPX RT 18);

[0067] Fig 3 a finely textured surface created using polymethylpentene structuring agent (MX004).

[0068] DESCRIPTION OF PREFERRED EMBODIMENTS

[0069] The following are formulation examples of powder coatings with previously commercially available PTFE structuring agents (each referred to as comparative example VB) and based on the new structuring agent (each referred to as example B):

[0070] Example 1 - Formulations of thermosetting powder coatings based on epoxy resins

[0071] 560 g of epoxy resin BM (bisphenol-A based, glass transition temperature Tg approx. 55 °C, epoxy equivalent weight EEW approx. 775 g / eq, Olin) were mixed with a stoichiometric amount of epoxy hardener HA (l-(o-tolyl)biguanide, AlzChem). 1-50 g of structuring agent were added. To this were added 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant), 15 g of iron oxide black pigment PI (Lanxess), 2 g of iron oxide yellow pigment PI (Lanxess), 110 g of titanium dioxide pigment PI (Huntsman), and 100 g of barium sulfate FU (average grain size approx. 4 pm, Sachtleben). The mixture was weighed to a total weight of 1000 g with the addition of calcium carbonate FU (average grain size approx. 5 pm, Omya).

[0072] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 110 °C. The extrudate was then ground into an application-ready powder coating using an impact mill with a classifier (Hosokawa Alpine). This powder coating was electrostatically applied to a steel panel (Q-Lab, R46, 152 x 101 x 0.8 mm) (layer thickness approximately 70-90 μm) and cured in a convection oven at 190 °C for 15 minutes.

[0073] In example B1, polymethylpentene (TPX RT18, Mitsui, median particle size approx. 10 pm) was used as the structuring agent.

[0074] In example VB1, PTFE powder SM (3M Dyneon TF 3220, particle size median D50 (mass-related) approx. 27 pm, determined according to ISO 13320-1 and DIN EN ISO 8130-13) was used as the structuring agent.

[0075] Example 2 - Formulations of thermosetting powder coatings based on epoxy and polyester resins

[0076] 400 g of carboxylated polyester resin BM (TG approx. 58 °C, acid number 70 mg KOH / g, Allnex) was mixed with 400 g of epoxy resin HA (bisphenol-A based, glass transition temperature TG approx.

[0077] 55 °C, epoxy equivalent weight EEW approx. 775 g / eq, Olin). 15 g of structuring agent were added. To this were added 10 g of talc (Imerys), 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant), 20 g of chromium oxide green pigment PI (Lanxess), 5 g of iron oxide yellow pigment PI (Lanxess), 60 g of titanium dioxide pigment PI (Huntsman),

[0078] 100 g of barium sulfate FU (average particle size approx. 4 pm, Sachtleben) was added. The mixture was weighed to a total weight of 1000 g with the addition of calcium carbonate FU (average particle size approx. 5 pm, Omya).

[0079] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 120 °C and then ground to powder using an impact mill with a classifier (Hosokawa Alpine). This powder was then electrostatically applied to a steel panel (Q-Lab, R46, 152 x

[0080] 101 x 0.8mm) (layer thickness approx. 70-90pm) and crosslinked in a convection oven at 160°C for 10 minutes.

[0081] In example B2, polymethylpentene (MX002, Mitsui, median particle size approx. 30 pm) was used as the structuring agent.

[0082] In example VB2, PTFE powder SM (3M Dyneon TF 3220, median particle size approx. 27 pm) was used as the structuring agent.

[0083] Example 3 - Formulations of thermosetting powder coatings based on polyester resins with glycidylic hardener

[0084] 570 g of carboxylated polyester resin BM (TG approx. 65 °C, acid number 34 mg KOH / g, Allnex) was mixed with a stoichiometric amount of a reaction mass of bis(2,3-epoxypropyl) terephthalate and tris(oxiranylmethyl)benzene-1,2,4-tricarboxylate HA (Huntsman). 20 g of structuring agent were added. Furthermore, 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant) and 300 g of titanium dioxide PI (Kronos) were added. The total mass was 1000 g-

[0085] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 120 °C and then ground into powder using an impact mill with a classifier (Hosokawa Alpine). This powder was electrostatically applied to an aluminum panel (Q-Lab, AT46, 152 x 101 x 0.8 mm) (layer thickness approximately 70-90 μm) and cured in a convection oven at 180 °C for 10 minutes.

[0086] In example B3, polymethylpentene (MX004, Mitsui, median particle size approx. 20 pm) was used as the structuring agent.

[0087] In example VB3, PTFE powder SM (3M Dyneon TF 3220, median particle size approx. 27 pm) was used as the structuring agent.

[0088] Example 4 - Formulations of thermosetting powder coatings based on polyester resins with glycidylic hardener

[0089] 660 g of carboxylated polyester resin BM (TG approx. 60 °C, acid number 34 mg KOH / g, Allnex) was mixed with a stoichiometric amount of triglycidyl isocyanurate HA (Huntsman). 10 g of structuring agent were added. 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant) and 7 g of pearl black PI (Orion Engineered Carbons) were also added. The mixture was weighed to a total weight of 1000 g with the addition of barium sulfate FU (average particle size approx. 4 μm, Sachtleben).

[0090] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 120 °C and then ground into a powder using an impact mill with a classifier (Hosokawa Alpine). This powder was electrostatically applied to an aluminum panel (Q-Lab, AT46, 152 x 101 x 0.8 mm) (layer thickness approximately 70-90 μm) and cured in a convection oven at 180 °C for 15 minutes.

[0091] In example B4, polymethylpentene (TPX RT18, Mitsui, median particle size approx. 10 pm) was used as the structuring agent.

[0092] In Example VB4, PTFE powder SM (3M Dyneon TF 3220, median particle size approx. 27 pm) was used as the structuring agent. Example 5 - Formulations of thermosetting powder coatings based on polyester resins with hydroxyalkylamide hardener

[0093] 712.5 g of carboxylated polyester resin BM (TG approx. 58 °C, acid number 33 mg KOH / g, Synthomer) was mixed with a stoichiometric amount of N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide HA (EMS). 40 g of structuring agent were added. 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant) and 7 g of pearl black PI (Orion Engineered Carbons) were also added. The mixture was weighed to a total weight of 1000 g with the addition of barium sulfate F11 (average particle size approx. 4 pm, Sachtleben).

[0094] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 110 °C and then ground into a powder using an impact mill with a classifier (Hosokawa Alpine). This powder was electrostatically applied to an aluminum panel (Q-Lab, AT46, 152 x 101 x 0.8 mm) (layer thickness approximately 70-90 μm) and cured in a convection oven at 180 °C for 10 minutes.

[0095] In example B5, polymethylpentene (MX002, Mitsui, median particle size approx. 30 pm) was used as the structuring agent.

[0096] In example VB5, PTFE powder SM (3M Dyneon TF 3220, median particle size approx. 27 pm) was used as the structuring agent.

[0097] Example 6 - Formulations of thermosetting powder coatings based on polyester resins with isocyanate hardener

[0098] 650 g of hydroxylated polyester resin BM (Tg approx. 51 °C, OH value 85 mg KOH / g, DSM) was mixed with a stoichiometric amount of uretdione-blocked isocyanate hardener HA (Tg approx. 48 °C, NCO content approx. 13.5%, Covestro). 35 g of structuring agent were added. To this were added 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant), 15 g of iron oxide black pigment PI (Lanxess), 2 g of iron oxide yellow pigment PI (Lanxess), and 110 g of titanium dioxide pigment PI (Huntsman). The mixture was weighed to a total weight of 1000 g with the addition of barium sulfate FU (average particle size approx. 4 μm, Sachtleben).

[0099] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 130 °C and then ground into a powder using an impact mill with a classifier (Hosokawa Alpine). This powder was electrostatically applied to an aluminum panel (Q-Lab, AT46, 152 x 101 x 0.8 mm) (layer thickness approximately 70-90 μm) and cured in a convection oven at 200 °C for 10 minutes. For example B6, polymethylpentene (MX002, Mitsui, median particle size approximately 30 μm) was used as the structuring agent.

[0100] In example VB6, PTFE powder SM (3M Dyneon TF 3220, median particle size approx. 27 pm) was used as the structuring agent.

[0101] Example 7 - Formulations of thermosetting powder coatings based on acrylic resins

[0102] 775 g of glycidyl group-containing acrylate resin BM (methacrylate-based, Tg approx. 50 °C, EEW approx. 500 g / eq, DIC) was mixed with a stoichiometric amount of 1,12-dodecanedicarboxylic acid HA (BASF). 50 g of structuring agent were added. In addition, 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant), 20 g of chromium oxide green pigment PI (Lanxess), 5 g of iron oxide yellow pigment PI (Lanxess), and 60 g of titanium dioxide pigment PI (Huntsman) were added (dropping point approx. 110 °C, Clariant). The mixture was weighed to a total weight of 1000 g with the addition of barium sulfate FU (average particle size approx. 4 pm, Sachtleben).

[0103] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 120 °C and then ground into a powder using an impact mill with a classifier (Hosokawa Alpine). This powder was electrostatically applied to an aluminum panel (Q-Lab, AT46, 152 x 101 x 0.8 mm) (layer thickness approximately 70-90 μm) and cured in a convection oven at 200 °C for 15 minutes.

[0104] In example B7, polymethylpentene (MX004, Mitsui, median particle size approx. 20 pm) was used as the structuring agent.

[0105] In example VB7, PTFE powder SM (3M Dyneon TF 3220, median particle size approx. 27 pm) was used as the structuring agent.

[0106] Results:

[0107] The powders according to the aforementioned examples were applied to a surface using a baking process as described. However, the powders can generally be applied to aluminum and steel substrates, as well as to various non-ferrous metals or sufficiently heat-resistant non-metallic substrates such as medium-density fiberboard, gypsum fiberboard, solid wood, or composite materials (e.g., glass-fiber-containing polymer composites).

[0108] The following processes can be used as a curing process:

[0109] The electrostatically powder-coated parts are heated using convection, induction, or infrared heating, which melts the powder coating particles and bonds them together through a certain degree of flow to form a continuous, ideally pore-free coating layer. A thermosetting layer is formed through chemical crosslinking. This can be thermally induced or triggered with the aid of UV or X-ray radiation, or electron beams. Crosslinking times range from a few seconds to 120 minutes, preferably between 1 and 30 minutes at temperatures between 80 and 250°C, preferably between 120 and 230°C.

[0110] Specific parameters of the coatings:

[0111] Gloss at a 60° measuring angle was determined according to DIN EN ISO 2813 (measuring instrument: BYK micro-TRI-gloss).

[0112] Surface roughness and mean roughness were determined according to ISO 21920-2 (measuring instrument: Jimtec JITAI8103, parameters Rz and Ra).

[0113] The following Tables 1 and 2 summarize the measured properties for examples B1-B7 and VB1 - VB7 respectively.

[0114] Table 1: measured values ​​for the coatings with new structuring agent

[0115] Table 2: measured values ​​for the coatings with PTFE structuring agent

[0116] Discussion:

[0117] Fig. 1 shows a finely textured surface created using PTFE structuring agents under

[0118] Use of powder VB6. Fig. 2 shows a finely textured surface created using the polymethylpentene structuring agent TPX RT 18 using powder B2.

[0119] Fig. 3 shows a finely textured surface created by polymethylpentene structuring agent MX004 using powder B5.

[0120] From the above, it is clear that the use of the new proposed structuring agent, along with conventional powder coating methods, allows the formation of a uniform, mechanically stable layer with the desired surface texture. The achievable gloss is in the same or similar range as when using conventional PTFE structuring agents, and the surface roughness can also be adjusted analogously. The results thus demonstrate that it is unexpectedly possible to replace the problematic PTFE structuring agent with the new structuring agent without sacrificing product properties and flexibility. Regardless of the powder coating system being processed, any surface roughness and gloss can be achieved with both PTFE and the new type of structuring agent within the specified gloss and roughness ranges by varying the amount of structuring agent.

[0121] The mean roughness indicates, in a sense, the uniformity of the coating. The specified value ranges can be adjusted by varying the amount of texturing agent. The data demonstrates that, in principle, any roughness can be adjusted in any powder coating system.

[0122] Formulations of thermosetting powder coatings based on polyester resins with hydroxyalkylamide hardener

[0123] 712.5 g of carboxylated polyester resin BM (TG approx. 58 °C, acid number 33 mg KOH / g, Synthomer) was mixed with a stoichiometric amount of N,N,N',N'-tetrakis(2-hydroxyethyl)adipamide HA (EMS). 40 g of polymethylpentene structuring agent were added. 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant) and 7 g of pearl black PI (Orion Engineered Carbons) were also added. The mixture was weighed to a total weight of 1000 g with the addition of barium sulfate F11 (average particle size approx. 4 pm, Sachtleben).

[0124] The homogeneously blended mixture was extruded using a single-screw extruder (PLK-46, Buss) at approximately 110 °C and then ground into a powder using an impact mill with a classifier (Hosokawa Alpine). This powder was electrostatically applied to an aluminum panel (Q-Lab, AT46, 152 x 101 x 0.8 mm) (layer thickness approximately 70-90 μm) and cured in a convection oven at 180 °C for 10 minutes. In this example, polymethylpentene (DX820, Mitsui, median particle size approximately 80 μm) filled with 60% borosilicate glass was used as the structuring agent.

[0125] Gloss (60°): 8

[0126] Surface roughness Rz (pm): 16

[0127] Average roughness Ra (pm): 2.5

[0128] Production of a filled polymethylpentene

[0129] Polymethylpentene copolymer (DX820, Mitsui, granules approx. 5 mm) was compounded with 60 wt.% borosilicate glass (average grain size approx. 8 pm, Alberto Luisoni AG) in a plastics extruder (Coperion ZSK) at approximately 300°C. The material was granulated for further processing (granules approx. 4 mm).

[0130] Grinding of the polymethylpentene structuring agent

[0131] Using a cryogenic mill (Wanrooe Machinery Co., Ltd.), polymethylpentene copolymer (DX820, Mitsui, granules approx. 5 mm) and polymethylpentene copolymer filled with 60% borosilicate glass (DX820, Mitsui, granules approx. 4 mm) were ground under liquid nitrogen. After protective sieving (mesh size 125 μm), pure polymethylpentene powder with a median particle size of approx. 80 μm was obtained (approx. 40 μm for the filled polymethylpentene).

[0132] Depending on the grinding parameters, coarser as well as finer grain sizes can be produced.

[0133] LIST OF REFERENCE SYMBOLS

[0134] BM Binder (binder SM Structural agents can contain functional groups AD Additive so that two HA Hardener provided Binder PI Pigment can harden together FU Filler)

Claims

PATENT CLAIMS 1. Use of polymethylpentene, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, as a structuring agent in a powder coating mixture or its precursor mixture for producing surface textures.

2. Use according to claim 1, characterized in that the polymethylpentene has a melting point of at least 210 °C, particularly preferably at least 220 °C, particularly preferably in the range of 220-240 °C, and / or that the polymethylpentene has a density in the range of 800-850 kg / m3 and / or that the polymethylpentene has a molecular weight in the range of 50,000 - 2,000,000 or 100,000-900,000, particularly preferably in the range of 200,000-700,000, and / or that the polymethylpentene has a surface tension in the range of 20-30 mN / m and / or that the polymethylpentene has a glass transition point in the range of 10-40 °C, particularly preferably in the range of 20-30 °C.

3. Use according to one of the preceding claims, characterized in that polymethylpentene is a polymethylpentene copolymer copolymerized with one or more of ethylene, propylene, butene, butadiene, pentene, pentadiene, hexene, heptene, octene, nonene and decene, styrene, methylstyrene, ethylstyrene, wherein the content of 4-methyl-1-pentene in the polymethylpentene copolymer is preferably at least 80% by weight or 95-100% by weight, and / or that the polymethylpentene is a polymethylpentene copolymer of 4-methyl-1-pentene and a C2-C20 monomer, wherein the C2-C20 monomer is different from 4-methyl-1-pentene, wherein the content of 4-methyl-1-pentene in the polymethylpentene copolymer is preferably at least 60% by weight or at least 80% by weight or 95-100% by weight.-%, and / or that the polymethylpentene is present as pure polymethylpentene or as a polymethylpentene copolymer or polymethylpentene derivative in a mixture with another polymer, preferably with a polyolefin different from polymethylpentene, in particular polypropylene, wherein the proportion of polymethylpentene in. this mixture is preferably at least 50 percent by weight, preferably at least 80 percent by weight, particularly preferably in the range of 90-100 or 95-100 percent by weight, and / or that the polymethylpentene is present as a polymethylpentene derivative in the form of a grafted polymethylpentene.

4. Use according to one of the preceding claims, characterized in that the polymethylpentene in the powder coating mixture or its precursor mixture is present with a median particle size in the range of 0.1 - 500 pm, preferably between 2 - 100 pm or in the range of 5-40 pm, preferably in the range of 10-30 pm.

5. Use according to one of the preceding claims, characterized in that the surface texture is a surface with a surface roughness (Rz) in the range of 1-100 pm, particularly preferably in the range of 2-50 pm and / or with a mean roughness value (Ra) in the range of 0.1 - 20 pm, particularly preferably in the range of 0.2 - 10 pm, and / or that the surface texture has a gloss at a measuring angle of 60° in the range of 1-50, preferably in the range of 10-40.

6. Powder coating mixture or its precursor mixture for producing surface textures, characterized in that the powder coating mixture contains polymethylpentene as structuring agent, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, preferably in a weight fraction in the range of 0.01-10%, preferably in the range of 0.1-5%.

7. Powder coating mixture or its precursor mixture according to the preceding claim, characterized in that it is a thermoplastic or a thermosetting powder coating mixture.

8. Powder coating mixture or its precursor mixture according to the preceding claim, characterized in that it is a thermosetting powder coating mixture, wherein the powder coating mixture is based on epoxy resins, on polyester resins, including polyester resins with glycidylic hardener, polyester resins with hydroxyalkylamide hardener, polyester resins with isocyanate hardener, on Based on acrylate resins, or on a mixture of one or more of these resins.

9. Powder coating mixture or its precursor mixture according to the preceding claim, characterized in that the polymethylpentene in the powder coating mixture or its precursor mixture is present with a particle size median in the range of 0.1 - 500 pm, preferably between 2 - 100 pm or in the range of 5-40 pm, preferably in the range of 10-30 pm.

10. A process for producing a powder coating mixture according to one of the preceding claims, characterized in that it contains polymethylpentene, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, as a structuring agent, preferably in a proportion by weight in the range of 0.01-10%, preferably in the range of 0.1-5%. With further components, in particular at least one binder and at least one hardener and optionally further fillers, additives and dyes or pigments, to form a precursor mixture and then extruded, followed by comminution of the extrudate to form an application-ready powder coating mixture, preferably in a mill, particularly preferably at a temperature below room temperature, or at a temperature of less than -100 °C, preferably using a mill. 11 . Process according to the preceding claim, characterized in that the structuring agent polymethylpentene is brought to a suitable particle size, in particular a particle size median in the range of 0.1 - 500 pm, preferably between 2 - 100 pm or in the range of 5-40 pm, preferably in the range of 10-30 pm, before addition, preferably by dissolving the polymethylpentene in a solvent and subsequently precipitating it, and / or by comminution, in particular by grinding in a mill, optionally multi-stage grinding, optionally followed by sieve separation.

12. Process according to the preceding claim, characterized in that an organic solvent, particularly preferably selected from the group or a mixture thereof, is used as the solvent, wherein preferably the polymethylpentene is dissolved at temperatures above its glass transition temperature but below the boiling temperature of the solvent and at temperatures precipitated below the boiling temperature of the solvent, whereby crystallization aids can be used.

13. The method according to claim 11 or 12, characterized in that a knife mill, a cutting mill, a classifier mill, a pin mill, a ball mill, a vibrating mill, or a drum mill or a sequence of identical or different ones of these mills can be used as the mill, wherein the milling temperature is preferably below room temperature and / or below the glass transition temperature of the polymethylpentene.

14. A method for producing a coated surface with a surface texture using a powder coating mixture according to one of the preceding claims 1-9, characterized in that the powder coating mixture is applied electrostatically to a substrate and then heated, preferably by convection, induction or infrared heating, as a result of which the powder coating grains melt and form a substantially continuous, preferably pore-free coating layer, wherein preferably chemical crosslinking takes place and a thermosetting layer is formed, wherein the crosslinking can be thermally induced or also by means of UV or X-ray radiation, or.Electron beams can be triggered, and wherein crosslinking times preferably range between 3-5 seconds up to 120 minutes, more preferably between 1 - 30 minutes, preferably at temperatures between 80 - 250°C, more preferably between 120 - 230°C, wherein preferably the surface texture is a surface with a surface roughness (Rz) in the range of 1-100 pm, particularly preferably in the range of 2-50 pm and / or with an average roughness (Ra) in the range of 0.1 - 20 pm, particularly preferably in the range of 0.2 - 10 pm, and / or the surface texture has a gloss at a measuring angle of 60° in the range of 1-50, preferably in the range of 10-40.

15. Use of a powder coating mixture according to one of the preceding claims for producing a coating, in particular on a metallic surface, wherein the coating is a surface with a surface roughness (Rz) in the range of 1-100 pm, particularly preferably in the range of 2-50 pm and a mean roughness value (Ra) in the range of 0.1 - 20 pm, particularly preferably in the range of 0.2 - 10 pm, and / or wherein the surface texture has a gloss at a measuring angle of 60° in the range of 1-50, preferably in the range of 10-40.

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