WO2025016990A1 - Matt powder coatings for producing textured surfaces - Google Patents

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

TITLE

POWDER MATT COATINGS FOR CREATING TEXTURED SURFACES

TECHNICAL FIELD

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.

STATE OF THE ART

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

After electrostatic application to a desired substrate, e.g. using powder coating guns, the parts are heated, which melts the powder coating grains at least to the extent that they flow together to form a continuous coating, which is preferably pore-free. In the case of thermosetting coatings, a chemical reaction takes place in the binder due to a hardener component that is present at the same time, which crosslinks the paint film and thus enables coatings that are very chemically resistant, depending on the crosslinking density. These crosslinking reactions typically take place 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 sufficient surface quality.

In order to diversify the surface appearance, powder coatings can also contain special additives that influence the gloss of the surface or the surface texture.

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

Coarse structures are often created by adding small amounts of additives to the paint formulation, which come to the surface during the melting process and change its surface tension inhomogeneously (e.g. cellulose acetate butyrates or silicone derivatives). This creates wavy, but not sandy surfaces.

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

The particularly popular surface type of fine structures, comparable to a sand-like surface in varying degrees of fineness, haptically soft or roughness, is a speciality in the coatings industry. The high popularity of these surfaces in the powder coatings 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.

According to the state of the art, these fine structures are created using fine-particle PTFE or similar halogenated plastics. These can be combined with other aids such as rheology-changing materials (e.g. pyrogenic silica, pyrogenic aluminum oxide, layered silicates or talc). The use of these substances changes the flow behavior of the coating in the molten state significantly, the viscosity increases significantly even with relatively small amounts added, which allows the desired surface textures to form. However, the latter materials only support the PTFE structure agent and can improve its efficiency. The small amounts of PTFE added allow a high degree of freedom in the formulation, including the ability to vary the amounts of binder over a wide range. This enables the targeted adaptation of formulations with regard to the mechanical properties and UV resistance of the paints in general. regardless 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 because lower binder contents lead to higher densities and poorer electrostatic chargeability.

The above-mentioned relationships show the importance of using small amounts of the agents used for texturing purposes (or their high effectiveness) for the powder coating industry. To date, only PTFE and similar halogenated, high-melting polymers have been established in the powder coating sector. Other polymers with a 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.

CN-A-103773127 discloses a low gloss reflective radiation shielding coating. The low gloss 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 additive. The radiation shielding coating has high extinction performance, high wear performance, excellent surface durability, high mechanical strength, excellent radiation performance and long service life.

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

EP-A-0456929 discloses a semi-transparent resin container with pearl grey gloss made from thermoplastic resins prepared by adding 0.01 to 0.9 wt.% polymethylpentene to 99.99 wt.% polyester resins, wherein the thermoplastic resins are subjected to biaxial orientation blow molding after preform molding. In this way, the pearl gray gloss of a container can be improved and, in addition, the strength of the container can also be improved.

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 polyacrylic acid flow agent containing no solvent is used as a prepreg, then 70-90 wt% of a mixed monomer capable of polymerization is dropped therein, 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, absence of solvents, waste reduction and the like, and conforms to the trend of environmental protection, and the manufactured polyacrylate flow agent can be used for flow filling and shrink-free hole filling of solvent or solvent-free systems and powder bodies.

PRESENTATION OF THE INVENTION

The present invention describes the use of halogen-free polymers as structuring agents with the aim of producing sand-like surface textures in powder coatings that are optically, mechanically, haptically and technically comparable to or even superior to those surfaces produced by PTFE and other halogenated polymers. For economic and/or ecological reasons, the halogenated structuring agents used in the state of the art are problematic and are likely to be severely restricted or even banned in the medium term for the purposes of use in a powder coating mixture. There is therefore a great need for alternatives.

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 the state-of-the-art structural agents based on halogenated hydrocarbons, in particular those based on PTFE, in an equivalent or even improved manner.

The present invention describes the use of polymethylpentene, its copolymers, derivatives and mixtures thereof for the production of powder coatings for the creation of sand-like surface textures of different intensity. For this purpose, polymethylpentene is introduced in particulate form in amounts between 0.01% - 10% into powder coating precursor mixtures and by extrusion processed. Polymethylpentene, its copolymers or structurally related polymers are, if necessary, brought into a finely divided form (grainy or fibrous) using suitable processes. The particle size of polymethylpentene, its copolymers or structurally related polymers is normally between 0.1 - 500 pm, preferably between 2 - 100 pm. By introducing these polymer particles, the rheology of the paint changes significantly and it is enabled to form finely textured surfaces even with small amounts added in the melting and crosslinking process.

Analogous to the use of PTFE as a structural agent, the particle size distribution is also important when using polymethylpentene. The particle size distribution of polymethylpentenes available on the market can be adjusted to the desired size (e.g. TPX RT18, Mitsui, to a median particle size of approx. 10 pm) using the following methods:

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 precipitated again at temperatures below the boiling temperature of the solvent. Inorganic or organic crystallization aids (e.g. as crystallization seeds) can be used for this. For example, the polymer itself or calcium fluoride or other inorganic solids can be used for this.

2. Grinding using knife mills below or above the glass transition temperature of the polymer. Grinding is preferably carried out at above -78 °C. The grinding process can be carried out with or without the use of grinding aids. Calcium fluoride or other inorganic solids can be used as grinding aids.

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 can be used as grinding aids, for example. 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 supported by the use of grinding aids such as steel balls.

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

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

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

What can be particularly helpful with regard to grinding is to fill the polymethylpentene polymer with a suitable filler beforehand (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, layered silicates, talc, fumed silica or fumed alumina). The polymethylpentene polymer then becomes more brittle and less impact-resistant and is easier to grind. For filling, the polymethylpentene polymer plastic granulate can be melted in a plastic extruder and compounded with filler.

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

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.

Polymethylpentene is preferably used to produce powder coatings that do not contain any additives or additive mixtures to particularly increase the temperature stability or the thermal conductivity. Polymethylpentene is preferably used to produce powder coatings that do not contain any (in particular non-pigment) additives or additive mixtures that have been calcined before being added to the powder coating, i.e. preferably have not been subjected to any treatment at a temperature of at least 500 °C for at least 1 hour.

Furthermore, the powder coating mixtures in which the polymethylpentene is used preferably do not contain any (high temperature stable and preferably calcined) aggregates 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 aggregates.

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, Rochelle salt, polysorbate, in particular polysorbate 80, aluminum nitride, or a combination.

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

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).

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

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).

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

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).

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% by weight or at least 80% by weight or 95-100% by weight.

The proposed use is preferably alternatively expressed 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% by weight or 95-100% by weight. 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.

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 other than 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.

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

A further preferred embodiment is 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.

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 an average roughness value (Ra) in the range of 0.1 - 20 pm, particularly preferably in the range of 0.2 - 10 pm.

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.

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 a structuring agent, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, preferably in a weight proportion in the range of 0.01-10%, preferably in the range of 0.1-5%.

This can be a thermoplastic or a thermosetting powder coating mixture.

Preferably, these are powder coatings that do not contain any additives or additive mixtures to increase the temperature stability or the Thermal conductivity. Preferably, these are powder coatings that do not contain any additives or additive mixtures that have been calcined before being added to the powder coating, i.e. preferably have not been subjected to any treatment at a temperature of at least 500 °C for at least 1 hour.

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.

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, Rochette salt, polysorbate, in particular polysorbate 80, aluminum nitride, or a combination.

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.

The polymethylpentene is preferably present in the powder coating mixture or its precursor mixture 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.

The present invention further 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 contained 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 constituents, 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 is then extruded, followed by comminution of the extrudate to form an applicable 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.

The process can be characterized in that the structuring agent Polymethylpentene is brought to a suitable particle size before addition, in particular a median particle size 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, preferably by dissolving the polymethylpentene in a solvent and then 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 point of the solvent and precipitated at temperatures below the boiling point of the solvent, wherein crystallization aids can be used.

The mill used can 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 identical 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.

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 an average 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.

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 then heated, preferably by convection, induction or infrared heating, whereby the powder coating grains melt and form an essentially continuous, preferably pore-free coating layer. In this case, chemical cross-linking preferably takes place and a thermosetting layer is formed, whereby the cross-linking can be thermally induced or can also be triggered with the aid of UV or X-ray radiation or electron beams, and whereby cross-linking times preferably range between 3-5 minutes up to 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 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.

Further embodiments are specified in the dependent claims.

SHORT DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below with reference to the figures, which are merely illustrative and are not to be interpreted as limiting. In the figures:

Fig. 1 a finely textured surface created using PTFE texturing agent;

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

(TPX RT 18);

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

DESCRIPTION OF PREFERRED EMBODIMENTS

The following are formulation examples of powder coatings with PTFE structuring agents that are currently available on the market (each referred to as comparative example VB) and based on the new structuring agent (each referred to as example B):

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

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), 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).

The homogeneously mixed mixture was extruded with a single-screw extruder (PLK-46, Buss) at approx. 110 °C. The extrudate was then milled with an impact mill with a classifier (Hosokawa Alpine) to form a powder coating that was ready for application. This was applied electrostatically to a steel panel (Q-Lab, R46, 152 x 101 x 0.8mm) (layer thickness approx. 70-90pm) and crosslinked in a convection oven at 190°C for 15 minutes.

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

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.

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

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.

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),

100 g of barium sulfate FU (average grain size approx. 4 pm, Sachtleben) were added. 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).

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

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

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

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

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

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. 3 g of micronized polyolefin wax AD (dropping point approx. 110 °C, Clariant) and 300 g of titanium dioxide PI (Kronos) were also added. The total mass was 1000 g-

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

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

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

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

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 grain size approx. 4 pm, Sachtleben).

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

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

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

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 Fll (average grain size approx. 4 pm, Sachtleben).

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

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

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

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

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), 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 grain size approx. 4 pm, Sachtleben).

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

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

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

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 grain size approx. 4 pm, Sachtleben).

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

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

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

Results:

The powders according to the above examples were applied to a surface in a baking process as described. However, the powders can generally be applied to aluminum and steel substrates, but also to various non-ferrous metals or sufficiently heat-resistant non-metallic substrates such as medium-density fiberboard, gypsum fiberboard, solid wood or composite materials such as glass fiber-containing polymer composites.

The following methods can be used as a firing process:

The electrostatically powder-coated parts are heated in convection, induction or infrared, whereby the powder coating grains melt and, to a certain extent, in terms of flow properties to form a continuous, ideally pore-free layer of paint. A thermosetting layer is formed through chemical cross-linking. This can be thermally induced or triggered with the aid of UV or X-ray radiation or electron beams. The cross-linking times range from a few seconds to 120 minutes, preferably between 1 - 30 minutes at temperatures between 80 - 250°C, preferably between 120 - 230°C.

Specific parameters of the coatings:

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

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

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

Table 1: measured values for the coatings with new structural agent

Table 2: measured values for the coatings with PTFE structural agent

Discussion:

Fig. 1 shows a finely textured surface created using PTFE structuring agent under

Use of powder VB6. Fig. 2 shows a finely textured surface produced by means of polymethylpentene structuring agent TPX RT 18 using powder B2.

Fig. 3 shows a finely textured surface produced by polymethylpentene structuring agent MX004 using powder B5.

From the above it can be seen that the use of the new proposed structuring agent using the usual powder coating methods allows the formation of a uniform, mechanically stable layer with the desired surface texturing. The achievable gloss is in the same or similar range as when using the usual PTFE structuring agents, and the surface roughness can also be adjusted in the same way. The results therefore show that it is unexpectedly possible to replace the PTFE structuring agent, which is problematic in many respects, with the new structuring agent without losing product properties and flexibility. It does not matter which powder coating system is being processed, any surface roughness and gloss can be created with both PTFE and the new type of structuring agent in the specified gloss and roughness ranges by varying the amount of structuring agent.

The average roughness value indicates the uniformity of the coating. The value ranges given can be adjusted by the amount of texturing agent. The data show that in principle any roughness can be adjusted in any powder coating system.

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

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-hydroxyethyljadipamide 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 Fll (average grain size approx. 4 pm, Sachtleben).

The homogeneously mixed mixture was extruded with a single-screw extruder (PLK-46, Buss) at 30 to approx. 110 °C and then ground to powder using an impact mill with a classifier (Hosokawa Alpine). This was applied electrostatically to an aluminum panel (Q-Lab, AT46, 152 x 101 x 0.8mm) (layer thickness approx. 70-90 pm) and crosslinked in a convection oven at 180°C for 10 minutes. In the example, polymethylpentene (DX820, Mitsui, median particle size approx. 80 pm) filled with 60% borosilicate glass was used as the structuring agent.

Gloss (60°): 8

Surface roughness Rz (pm): 16

Average roughness Ra (pm): 2.5

Preparation of a filled polymethylpentene

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

grinding of the polymethylpentene structuring agent

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 with the aid of liquid nitrogen. After protective sieving (sieve mesh size 125 pm), pure polymethylpentene powder with a median particle size of approx. 80 pm was obtained (in the case of the filled polymethylpentene, approx. 40 pm).

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

REFERENCE SYMBOL LIST

BM binder (binder SM structural agents can contain functional groups AD additive so that two HA hardeners 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 other than 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 an average 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 a structuring agent, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, preferably in a weight proportion 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 acrylic 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 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. 10. Process for producing a powder coating mixture according to one of the preceding claims, characterized in that the structuring agent contains polymethylpentene, in the form of pure polymethylpentene, a polymethylpentene copolymer, a derivative of polymethylpentene or a mixture containing these, 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, is mixed to form a precursor mixture and then extruded, followed by comminution of the extrudate to form an applicable 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 before addition, 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, preferably by dissolving the polymethylpentene in a solvent and then 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 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 the mill used is 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, wherein the grinding 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 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 convection, induction or infrared heating, whereby 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 can also be triggered by means of UV or X-ray radiation or electron beams, and wherein crosslinking times preferably range between 3-5 minutes up to 120 minutes, preferably between 1 - 30 minutes, preferably at temperatures between 80 - 250°C, 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 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 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.