COATING PROCESS, ESPECIALLY BY SOLVENT EVAPORATION, FOR COATING A SUBSTRATE, ESPECIALLY A SUBSTRATE OF COMPLEX SHAPE, WITH A COMPOSITE COATING

Description

COATING PROCESS, ESPECIALLY SOLVENT-BASED EVAPORATION, TO COAT A SUBSTRATE, ESPECIALLY A COMPLEX SHAPE SUBSTRATE, WITH A COMPOSITE COATING Field of invention The present invention relates to the field of coating processes of substrates. State of the art Coating technologies for the functionalization of substrates that are adopted in industrial practice are PVD (Physical Vapor Deposition), CVD (Chemical Vapor Deposition), electrodeposition, electroless, fluidized bed, thermal spray, painting and cladding. The main critical issues of CVD are the high environmental impact and the temperature achieved in the process. Furthermore, the coating is limited to the surfaces directly exposed to steam. The main critical points of PVD are the high environmental impact and the geometry of the sample that does not allow the application of the process in continuous mode. The main criticality of electrodeposition is its applicability exclusively to electrically conductive substrates. The main critical points of the electroless technique are the toxicity of the process and the poor adhesion of the coating to the substrate. The main critical issues of the fluidized bed are the timing and the limitations geometric characteristics that the substrate must have in order to be coated. The main critical points of the cladding technique are linked to the need to be able to apply the coating on substrates resistant to high temperatures. Furthermore, with With this technique, only high-thickness coatings can be obtained. The main critical points of painting are the high environmental impact and the limitation of the materials that can be used. There is therefore a need to overcome the limitations of the state of the art. Summary of the invention An object of the present invention is to provide a coating process that allows you to coat a substrate without any particular limitations imposed by the substrate geometry. In particular, an object of the invention is to provide a process that allows coat a substrate without particular limitations imposed by the properties of the substrate, in particular a process that allows coating a substrate that is not is necessarily electrically conductive. In particular, an object of the invention is to provide a coating process low environmental impact and particularly easy to perform. The present invention achieves at least one of these objects, and other objects that will be evident in the light of this description, through a process for to coat a substrate, or body or piece or component, with a coating composite, the composite coating comprising a polymer matrix and particles, in particular reinforcing and / or functional particles, dispersed in said matrix polymeric, the process including the phases of: a) dissolve a polymer in a solvent to obtain a solution and / or dispersion and / or polymer suspension; b) disperse said particles in the solution and / or dispersion and / or suspension polymer to obtain a mixture; c) cover the substrate with said mixture; d) evaporate the solvent from the mixture covering the substrate; where after step d) said substrate is obtained coated with said coating composite comprising a polymer matrix and particles, in particular particles reinforcing and / or functional, dispersed in said polymer matrix said process being in particular a coating process by solvent evaporation. The invention also relates to a substrate according to claim 15. Advantageously, the process according to the invention is suitable for carrying out on substrates, even those having complex geometries, a composite matrix coating polymer with particle reinforcement. The particles can for example be filler particles. The process exploits in particular the solvent-based technology evaporation. Advantageously, a process according to the invention allows to coat a substrate, even of complex shape, without particular limitations imposed by the substrate geometry. Advantageously, a process according to the invention allows to coat a substrate without particular limitations imposed by the properties of the substrate, in In particular, the process allows you to coat a substrate that is not necessarily electrically conductive. Advantageously, a process according to the invention is low impact environmental and can be performed in a particularly easy way. The coating can advantageously provide a functionalization for the purposes thermal and / or electrical and / or mechanical and / or shielding. In particular, advantageously, a process according to the invention allows to confer physical and / or chemical and / or mechanical surface properties that are improved compared to the same ones of the substrate without said coating. In in particular, through the said process, in particular solvent-evaporation, and using particles of materials with specific properties, it is possible to transfer the latter to the substrate obtaining a homogeneous and functional coating. Therefore, advantageously, a process according to the invention allows to improve the surface properties of the substrate. Advantageously, there is no specific limitation on the type of particles which can be used. In particular, reinforcements can be used particles having a maximum size from 900 µm to 1 nm, with the possibility of use ceramic, polymeric, metallic, bio-derived materials or materials innovative such as carbon allotropes (nanotubes, diamond, graphene and derivatives, and fullerenes), 2D materials (hexagonal boron nitrate, molybdenum / tungsten disulfide, M- Xenes, LDH, etc.) or 1D materials (BNNT, MOS2NT, BPNT, etc.). By means of the process according to the invention it is possible to transfer the properties particle specifications (e.g. filler) to the substrate having geometry substantially two-dimensional or three-dimensional, even of complex shape, creating a homogeneous and functional coating. Advantageously, there is no specific limitation on the material constituting the polymer matrix of the coating, which may for example be a polymer of thermoplastic, thermosetting or elastomeric nature. Depending on the polymer used, the corresponding solvent is chosen, for example example water, alcohols, polar solvent, non-polar solvent, organic solvent, inorganic solvent. The process does not impose any particular limitations either in terms of material of the substrate that its shape (which can also be a complex 3D shape). The process advantageously does not require the use of electricity, need for the presence of an electrically conductive substrate and, given the absence of high temperatures, does not present limitations related to a possible thermal degradation. The process, for example, allows for obtaining coatings on metals, polymers, synthesis, bio-derived polymers (e.g. paper), natural polymers (wood and its derivatives), glasses, composites, ceramics, minerals or rocks. The substrate or component obtained at the end of the process has improved properties compared to the uncoated substrate. For example, the coated substrate may have one or more of the following characteristics: high thermal and / or electrical conduction, resistance to corrosion and / or environmental degradation, protection from agents biological and / or viral, hydrophobicity and / or surface tension properties, properties fire retardant, wear resistance and / or increased hardness, fatigue resistance and / or self-healing. The advantages of a process according to the invention include: - versatility of the process; absence of geometric and / or chemical-physical limitations of the substrate; costs reduced; high industrial scalability; limited and / or negligible environmental impacts (in function of the polymer constituting the matrix); high surface properties functionalizable based on the particles (e.g. filler) selected. Given the high versatility of the process according to the invention, the industrial uses are extremely varied, including, by way of example and not limited to the following: applications in the structural field both internally and externally due to the resistance to aggressive environmental agents that the coating can impart to the substrate; use in furniture components for the antibacterial and antiviral properties it can provide to the substrate, or increase of the tribological properties of components mechanics. Possible application sectors could be, for example: aerospace, structural, healthcare, precision mechanics, nano and micro electronics, design and furniture, naval, thermal applications. Further features and advantages of the invention will become more apparent. evident in light of the detailed description of embodiments exemplary, but not exclusive. The dependent claims describe particular embodiments. of the invention. Brief description of the figures In the description of the invention, reference is made to the attached drawing, which is provided by way of example and not limitation, where: Fig. 1 illustrates an example of a substrate, or body, that can be coated by a process according to the present invention. Description of exemplary embodiments of the invention Exemplary embodiments of a process for to coat a substrate 1, or body or piece or component, with a coating composite, the composite coating comprising a polymer matrix and particles, in particular reinforcing and / or functional particles, dispersed in said matrix polymeric. In all embodiments, the process comprising the steps of: a) dissolving a polymer in a solvent to obtain a polymer solution and / or a polymer dispersion and / or a polymer suspension; b) disperse said particles in the solution and / or dispersion and / or suspension polymer to obtain a mixture; c) cover, at least partially for example completely, the substrate 1 with said mixture; d) evaporate the solvent from the mixture covering substrate 1; where after step d) said substrate 1 is obtained coated with said coating composite comprising a polymer matrix and particles, in particular particles reinforcing and / or functional, dispersed in said polymer matrix said process being in particular a coating process by solvent evaporation. Said substrate 1, or body or piece or component, may be a non-substrate planar, especially not having a completely flat surface. Said substrate 1, or body or piece or component, may have a shape, in particular a complex shape, having at least one curved portion and / or at least one undercut and / or at least one hole or opening. In general, the substrate 1, or body or piece or component, may have a shape complex. By complex form we mean in particular a form that presents variations in curvature and / or specific characteristics that are high compared to the size overall substrate. Additionally, or alternatively, a complex shaped substrate can have any areas not visible through simple projection views, such as for example undercuts and / or internal or limited access areas. The polymer that can be used to make the polymer matrix, i.e. the polymer usable in phase a), can be selected from: thermosetting polymers; thermoplastic polymers; elastomeric polymers; natural polymers (e.g. cellulose, starch, proteins); polysaccharide gels. The solvent used in step a) is selected based on the polymer. The solvent used in step a) can for example be selected from: water, polar organic solvents (e.g. ethanol and butyl acetate), organic solvents non-polar (e.g. hexane, benzene), mixtures of organic solvents and / or water, mixtures of commercial solvents such as white spirit and slow solvent. Preferably, the percentage ratio by weight of said particles and said polymer matrix is ​​from 10% to 90%, said percentage ratio being in 𝑖𝑚𝑔𝑟𝑚𝑎 𝑒𝑒𝑡𝑑𝑡 𝑙𝑙𝑒𝑟𝑝𝑖𝑐𝑒𝑡𝑎 𝑖𝑛 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 particular expressed according to the formula %. 𝑖𝑚𝑔𝑟𝑚𝑎 𝑟𝑜𝑝𝑜𝑙𝑖𝑚𝑒 𝑖𝑛 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 Ratios lower than 10% do not allow the formation of a network of particles (filler) continuous and effective significantly decreasing performance, for example of thermal and / or electrical conduction of the coating. It also reduces the interaction between the particles (fillers) and the external environment, inhibiting the functionality particle specifications such as: antibacterial properties, properties hydrophobic or hydrophilic, catalytic and low surface friction functionality. Ratios higher than 90% do not allow for suitable fixing to the substrate making the coating essentially unusable. 𝑑𝑖 𝑑𝑖 Concentrations in the identified range allow for good or excellent performance, maintaining suitable adhesion of the coating to the substrate. Preferably, in phase b) the percentage ratio between the sum of the weight of the polymer matrix and weight of said particles / volume of solvent at temperature environment is from 0.1% to 30%, this percentage ratio being in particular expressed according to the formula 𝑖𝑚𝑔𝑟𝑚𝑎 𝑜𝑝𝑜𝑙𝑖𝑚𝑒 𝑟 𝑖𝑛 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 + 𝑖𝑚𝑚𝑎𝑔𝑟 𝑒𝑒𝑡𝑑𝑡 𝑟𝑝𝑖𝑐𝑒𝑡𝑎𝑙𝑙𝑒 𝑖𝑛 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 %. 𝑟𝑙𝑖𝑡𝑖 𝑜𝑙𝑣𝑒𝑒𝑠𝑛𝑡 𝑖𝑛 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 This ratio essentially defines the coating / solvent ratio defined as the weight / volume percentage between the materials constituting the matrix and the reinforcement (i.e. particles) and the volume of solvent at room temperature. Ratios lower than 0.1% preclude the formation of a continuous layer of composite coating, not imparting improved properties to the substrate. Concentrations above 30% result in a viscosity such that the correct thickness control. Furthermore, it is difficult to define details in complex geometries, such as localized missing coating, blocking holes or recesses and modifying angles on sharp edges. Preferably, in step a) the polymer concentration in the solvent is from 0.01% to 50% by weight, said concentration being specifically expressed 𝑖𝑚𝑔𝑟𝑚𝑎 𝑟𝑜𝑝𝑜𝑙𝑖𝑚𝑒 𝑖𝑛 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 according to the formula % 𝑖𝑚𝑔𝑟𝑚𝑎 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 Preferably, in phase b) the concentration of said particles in the mixture is from 0.01% to 50% by weight, said concentration being specifically expressed 𝑖𝑚𝑔𝑟𝑚𝑎 𝑒𝑒𝑡𝑑𝑡 𝑙𝑙𝑒𝑟𝑝𝑖𝑐𝑒𝑡𝑎 𝑖𝑛 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 according to the formula %. 𝑖𝑚𝑔𝑟𝑚𝑎 𝑐𝑒𝑖𝑠𝑙𝑎𝑚 Optionally, one or more additive materials can be added to the mixture and / or surfactants and / or surfactants to improve the dispersion of the particles in the solvent and, consequently, improve the uniformity of the coating. Such materials include but are not limited to: CTAB, SDS, PEG, Hydroxypropylcellulose, hydroxymethylcellulose, hydroxypropylmethylcellulose, lauryl ethoxysulfate, benzalkonium chloride, polyacrylic acid or combinations thereof. The relationship between the one or more materials and the aforementioned particles (fillers) can be defined by percentage ratio by weight. The percentage ratio by weight between said one or 𝑑𝑖 𝑑𝑖 𝑑𝑖 𝑑𝑖 𝑑𝑖 𝑑𝑖 𝑑𝑖 most materials and particles can be up to 100% by weight, especially from 0% (without said materials) 100%. The use of additive(s) and / or surfactant(s) and / or surfactant(s) is optional in the case of particles easily dispersible in the chosen solvent, reducing cost, complexity and environmental impact of the coating technology. The adoption of additives are useful when a homogeneous and stable dispersion is not observed of the particles (filler) in the solvent, which leads to the formation of localized clusters in the coating or alteration of the concentration of suspended particles in the time. Concentrations above 100% do not lead to significant improvements in quality of the dispersion, but altering the environmental and economic impact of the product and its performance. Preferably, before said phase c), a pre-treatment phase is foreseen substrate 1 for the removal of surface impurities from the substrate and / or to promote the adhesion of the composite coating; in particular called pretreatment includes a mechanical and / or chemical and / or electrochemical and / or physicist. Examples of mechanical treatments are: sandblasting, shot peening, tumbling, hammering and lapping. Examples of chemical treatments are: acid etching, basic etching; degreasing and / or pickling, electropolishing. Examples of physical treatments are: use of laser beam, use of cold plasma, use of hot plasma, corona treatment, use of electron beam, use of ion beam, use of UV light, cleaning by ionized air. Preferably, in phase b) the dispersion of said particles is performed by mechanical and / or magnetic and / or ultrasonic and / or air agitation tablet. Preferably, in step c) the substrate 1 is immersed in said mixture or This mixture is applied to the substrate 1, preferably by spraying of the mixture or by drop casting the mixture. Optionally, a polymer matrix curing phase is foreseen. composite coating and / or alteration of the composite coating, in particular by heat treatment and / or UV and / or sintering; this is the curing phase and / or alteration of the composite coating being performed in particular after phase d). Preferably, said coating has a thickness of 1 µm to 2 mm. Preferably, said particles are particles of one or more low dimensions. materials (LDM), especially 0D, preferably fullerenes, carbon dots, carbon onions, quantum dots, nano particles, and / or 1D, preferably nanotubes, nanowires, nanobars, nanoribbons, and / or 2D, preferably graphene, hexagonal boron nitrate, disulfides, monolayer of transition metal chalcogenides. The evaporation of the solvent in step d) can for example be performed at room temperature or at a temperature higher than the room temperature environment. Optionally, the substrate 1 coated with said coating is coated with at least one further layer of coating, preferably metallic. This additional coating layer can have for example one from 1 µm to 2 mm. Optionally, this additional coating layer is made by electrodeposition and / or chemical vapor deposition (CVD) and / or physical deposition steam (PVD) and / or cladding. An advantageous example involves coating a substrate 1 that is not electrically conductive with a polymer matrix composite coating in which electrically conductive particles are dispersed and optionally apply a additional coating layer by, for example, electrodeposition. The invention also relates to a substrate 1 coated with said coating composite comprising a polymer matrix and particles, in particular particles reinforcing and / or functional, dispersed in said polymer matrix, obtained by means of a process according to the present invention. Optionally, the substrate coated with said coating is removed substrate, in order to obtain a three-dimensional structure, in particular self- standing, consisting of said covering; in particular in which the substrate is removed by chemical and / or thermal attack and / or by deflating the substrate and / or by dismantling the substrate. For example, the substrate to be coated can be a deflatable or removable mandrel, e.g. similar to those used in filament winding; or the substrate to be coated can be a friable resin. On the structure resulting from the removal of the substrate can optionally be performed a treatment to further increase the surface properties, for example for example through at least one treatment chosen between mechanical treatment, chemical treatment, electrochemical treatment and beam treatment concentrated energy. Optionally, the structure resulting from the removal of the substrate can be fixed to another structure, preferably obtained by a process according to the present invention. For example, on a structure with electrical conductivity capacity it is possible carry out a subsequent metallization to make a connection possible with another structure using the brazing-welding technique. Optionally, at the end of the product's life, it is possible using an appropriate solvent recover the raw materials constituting said particles and the polymer matrix for a possible reuse of the same and / or for an appropriate subsequent process of disposal. In one experimental example, a substrate made by additive manufacturing, especially of the FFF type. The substrate was made of PLA (Polylactic acid). A solution was then prepared using polyacrylic acid (as a polymer for the formation of the polymer matrix) and water (as solvent). The particles dispersed in phase b) were graphene GNP nanoplatelets in a 1:1 weight ratio. The mixture was appropriately sonicated and then used to coat the substrate via drop casting (solvent casting). The process was characterized by an extreme ease of realization and Once the samples were obtained, they were tested using a capable instrument to measure electrical resistance by recording a decrease in resistance electrical from the order of 10E+09 Ω to 10E+04 Ω with respect to the uncoated substrate. It is recorded a 65% reduction in wear volume in the ball flat test compared to the uncoated substrate.

Claims

1. Process for coating a substrate (1) or body with a composite coating, the composite coating comprising a polymer matrix and particles, in particular reinforcing and / or functional particles, dispersed in said polymer matrix, the process comprising the steps of: a) dissolving a polymer in a solvent to obtain a polymer solution and / or dispersion and / or suspension; b) dispersing said particles in the polymer solution and / or dispersion and / or suspension to obtain a mixture; c) coating the substrate with said mixture; d) evaporating the solvent from the mixture which covers the substrate; wherein after step d) said substrate (1) is obtained coated with said composite coating comprising a polymer matrix and particles, in particular reinforcing and / or functional particles, dispersed in said polymer matrix, said process being in particular a solvent-evaporation coating process.

2. Process according to claim 1, wherein said substrate (1) is a non-planar substrate.

3. Process according to claim 1 or 2, wherein said substrate (1) has a shape, in particular a complex shape, having at least one curved portion and / or at least one undercut and / or at least one hole or opening.

4. Process according to any of the preceding claims, wherein the percentage ratio by weight of said particles and said polymer matrix is ​​from 10% to 90%, said percentage ratio being in particular expressed according to the grams of said particles in mixture formula gt ammt of said particles excel ni mixture % grams of polymer in mixture ' 5. Process according to any of the preceding claims, wherein in step b) the percentage ratio between the sum of the weight of the polymer matrix and the weight of said particles / volume of solvent at room temperature is from 0.1% to 30%, said percentage ratio being in particular expressed according to the formula grams of polymer in mixture + grams of said particles in mixture Q / liters of solvent in mixture %.

6. Process according to any of the preceding claims, wherein in step a) the concentration of polymer in the solvent is from 0.01% to 50% by weight, said concentration being in particular expressed according to the formula grams of polymer in mixture n / ----%~τ~·—;---% grams of mixture 7. Process according to any of the preceding claims, wherein in step b) the concentration of said particles in the mixture is from 0.01% to 50% by weight, said concentration being in particular expressed according to the formula grams of said particles in mixture n / _____________ %.....·—;-----------%. grams of mixture 8. Process according to any of the preceding claims, wherein before said step c), a pre-treatment step of the substrate (1) is provided for the removal of surface impurities from the substrate and / or to promote the adhesion of the composite coating; in particular wherein said pre-treatment comprises a mechanical and / or chemical and / or electrochemical and / or physical treatment.

9. Process according to any of the preceding claims, wherein in step b) the dispersion of said particles is carried out by mechanical and / or magnetic and / or ultrasonic and / or compressed air stirring.

10. Process according to any of the preceding claims, wherein in step c) the substrate (1) is immersed in said mixture or said mixture is applied to the substrate (1), preferably by spraying the mixture or by drop casting the mixture.

11. A process according to any of the preceding claims, wherein a curing step of the polymer matrix of the composite coating and / or an alteration of the composite coating is provided, in particular by heat treatment and / or by UV and / or sintering; said curing step and / or alteration of the composite coating being in particular carried out after step (d).

12. A process according to any preceding claim, wherein said coating has a thickness of 1 µm to 2 mm.

13. A process according to any of the preceding claims, wherein said particles are particles of one or more low dimensional materials (LDM), in particular 0D, preferably fullerenes, carbon dots, carbon onions, quantum dots, nano particles, and / or 1D, preferably nanotubes, nanowires, nanobars, nanoribbons, and / or 2D, preferably graphene, hexagonal boron nitrate, disulfides, monolayers of transition metal chalcogenides. P023956IT-01 Notarbartolo & Gervasi SpA 14. Process according to any of the preceding claims, wherein the substrate (1) coated with said coating is coated with at least one further coating layer, preferably metallic.

15. Process according to claim 14, wherein said further coating layer is made by electrodeposition and / or chemical vapor deposition (CVD) and / or physical vapor deposition (PVD) and / or cladding.

16. A process according to any of the preceding claims, wherein the substrate is removed from the substrate coated with said coating, so as to obtain a three-dimensional structure consisting of said coating; in particular wherein the substrate is removed by chemical and / or thermal etching and / or by deflating the substrate and / or by disassembling the substrate.

17. Substrate (1), or body, coated with said composite coating comprising a polymeric matrix and particles, in particular reinforcing and / or functional particles, dispersed in said polymeric matrix, obtained by a process according to any of the preceding claims.