Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/03—Powdery paints
  • C09D5/031—Powdery paints characterised by particle size or shape
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/03—Powdery paints
  • C09D5/033—Powdery paints characterised by the additives
  • C09D5/035—Coloring agents, e.g. pigments
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/02—Processes for applying liquids or other fluent materials performed by spraying
  • B05D1/04—Processes for applying liquids or other fluent materials performed by spraying involving the use of an electrostatic field
  • B05D1/06—Applying particulate materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
  • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
  • C08G69/08—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from amino-carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/12—Powdering or granulating
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/201—Pre-melted polymers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/203—Solid polymers with solid and/or liquid additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/24—Crosslinking, e.g. vulcanising, of macromolecules
  • C08J3/247—Heating methods
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/01—Use of inorganic substances as compounding ingredients characterized by their specific function
  • C08K3/013—Fillers, pigments or reinforcing additives
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/02—Elements
  • C08K3/04—Carbon
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
  • C08L77/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D177/00—Coating compositions based on polyamides obtained by reactions forming a carboxylic amide link in the main chain; Coating compositions based on derivatives of such polymers
  • C09D177/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/80—Processes for incorporating ingredients
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B14/00—Arrangements for collecting, re-using or eliminating excess spraying material
  • B05B14/10—Arrangements for collecting, re-using or eliminating excess spraying material the excess material being particulate
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
  • B05B7/00—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas
  • B05B7/14—Spraying apparatus for discharge of liquids or other fluent materials from two or more sources, e.g. of liquid and air, of powder and gas designed for spraying particulate materials
  • B05B7/1404—Arrangements for supplying particulate material
  • B05B7/1454—Arrangements for supplying particulate material comprising means for supplying collected oversprayed particulate material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D2202/00—Metallic substrate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
  • C08J2377/02—Polyamides derived from omega-amino carboxylic acids or from lactams thereof
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2237—Oxides; Hydroxides of metals of titanium
  • C08K2003/2241—Titanium dioxide
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2289—Oxides; Hydroxides of metals of cobalt
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/014—Additives containing two or more different additives of the same subgroup in C08K
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P20/00—Technologies relating to chemical industry
  • Y02P20/50—Improvements relating to the production of bulk chemicals
  • Y02P20/582—Recycling of unreacted starting or intermediate materials

Definitions

• This patent application relates to a pigmented powder composition for coating easily recyclable substrates. It also relates to a process for manufacturing such a composition, the use of this composition for coating substrates, in particular metallic ones, as well as the objects coated with a coating that can be obtained.
• polymer powders to manufacture substrate coatings, in particular metallic ones. These powders are formulated from a resin, one or more pigments and specific additives such as plasticizers, stabilizers or flow agents.
• the pulverulent composition is applied to the substrate in the form of loose powder, for example by electrostatic spraying or by immersion of the substrate in a fluidized bed of powder, and therefore does not require a solvent or binder.
• the polymers used for the manufacture of powders are usually thermosetting resins, but it is also possible to use thermoplastic polymers.
• Polyamides are, due to their high chemical and thermal resistance, the polymers of choice for demanding applications, such as the coating of dishwasher baskets for example.
• the powder composition for coating substrates can be manufactured according to various methods.
• the object of the invention is therefore to propose a process for the manufacture of a powdery pigmented composition based on polyamide for the coating of substrates based on polyamide which has an appearance, in particular in terms of color and gloss, and properties, in particular mechanical, which are not altered even after recycling while being inexpensive.
• the present invention is based on the finding that a pigmented powder composition based on easily recyclable polyamide can be obtained by incorporating the pigment(s) into the low-viscosity polyamide in the molten state, the mixture then being crushed and then ground. before being subjected to a heat treatment step to reach the target viscosity of the polyamide.
• the subject of the invention is a pigmented powder composition based on polyamide for coating substrates, comprising:
• the polyamide is chosen from PA 9, PA 10, PA 11, PA 12, PA 610, PA 612, PA 614, PA 618, PA 1010, PA 1012. According to one embodiment, the polyamide is a polyamide 11.
• the pigment is chosen from titanium dioxide, carbon black, cobalt oxide, nickel titanate, molybdenum disulphide, aluminum flakes, iron oxides, zinc oxide, zinc phosphate, and organic pigments, such as phthalocyanine and anthraquinone derivatives.
• the composition comprises 50 to 95% by weight of at least one polyamide. According to one embodiment, the composition comprises 1 to 30% by weight of at least one additive chosen from anti-crater agents, spreading agents, reducing agents, antioxidants, reinforcing fillers, UV stabilizers, fluidizing agents and corrosion inhibitors.
• the polyamide has an inherent viscosity, as measured using an Ubbelohde tube at 20° C. on a 0.5% by weight solution in m-cresol according to the ISO 307 standard, except that the measurement temperature is 20°C instead of 25°C, less than 1.0 (g/100g) 1 .
• the subject of the invention is a process for the manufacture of such a pigmented powder composition, comprising the steps of:
• step (ii) extruding the mixture obtained in step (i) into an extrudate
• step (iii) grinding the extrudate obtained in step (ii) into a powdery composition
• step (iv) polycondensation in solid phase of the pulverulent composition obtained in step (iii) until the polyamide in the composition has an inherent viscosity greater than 0.8 (g/100 g) 1 .
• the polyamide used in step (i) has an inherent viscosity of less than 0.4 (g/100 g) 1
• step (ii) is carried out in a single-screw extruder or a twin-screw extruder.
• step (Iv) is carried out in a dryer.
• the subject of the invention is the use of such a composition for coating a substrate, in particular a metal substrate.
• the coating is produced by electrostatic spraying or hot powdering.
• the subject of the invention is an object comprising a metal substrate coated with a coating obtained with such a pigmented powder composition.
• it is a pipe, an accessory, a pump, or a valve, a splined shaft, a sliding door track or springs, in particular of the truck or car seat shock absorber type, and in particular therefore parts used in automobile construction, or even a dishwasher basket or springs.
• inherent viscosity means the viscosity of a polymer in solution, determined using Ubbelohde tube measurements. The measurement is carried out on a 75 mg sample at a concentration of 0.5% (m/m) in m-cresol.
• the viscosity of a composition comprising, in addition to the polymer, any pigments and fillers insoluble in m-cresol is determined by increasing the quantity of the sample so that the solution has a polymer concentration of 0.5% (m /m).
• melting temperature means the temperature at which an at least partially crystalline polymer changes to the viscous liquid state, as measured by differential scanning calorimetry (DSC) according to standard NF EN ISO 11357-3 using a heating rate of 20°C/min.
• glass transition temperature is understood to denote the temperature at which an at least partially amorphous polymer changes from a rubbery state to a glassy state, or vice versa, as measured by differential scanning calorimetry (DSC) according to the standard NF EN ISO 11357-2 using a heating rate of 20°C/min.
• polyamide is understood to denote the polycondensation products of lactam(s), of amino-carboxylic acid(s) or of dicarboxylic acid(s) and diamine(s) and, in general, any polymer formed by units linked together by amide functions.
• the term “average diameter by volume” or “Dv” is also understood to mean the average diameter by volume of a pulverulent material, as measured according to standard ISO 9276 - parts 1 to 6: “Representation of data obtained by particle size analysis ".
• the Dv50 designates the median diameter by volume, that is to say that corresponding to the 50th percentile by volume
• the DvlO and Dv90 respectively designate the average diameters by volume below which 10 or 90% are located. in particle volume.
• the volume-average diameter can be measured in particular by means of a laser particle sizer, for example a laser particle sizer (Malvern System Insitec).
• Associated software RT sizer then makes it possible to obtain the volumetric distribution of a powder and to deduce the Dv10, the Dv50 and the Dv90.
• the invention relates to a pigmented powder composition based on polyamide intended to form a coating on a substrate.
• the polyamide(s) of interest for this pulverulent composition can in principle be chosen from the multitude of polyamides available on the market.
• they are semi-crystalline polyamides, in particular linear aliphatic polyamides, and in particular polyamides derived from monomers comprising 9 or more, preferably 10 or more, carbon atoms.
• ⁇ , ⁇ -aminocarboxylic acids having from 6 to 18 carbon atoms, such as amino-caproic acid, 7-heptanoic acid, amino-9-nonanoic acid, amino- 10-decanoic, amino-ll-undecanoic and amino-12-dodecanoic acid.
• ⁇ , ⁇ -aminocarboxylic acids having 9 to 18 carbon atoms such as amino-11-undecanoic acid and amino-12-dodecanoic acid are preferred.
• Monomers of the “diamine.diacid” type result from the condensation of a dicarboxylic acid with a diamine.
• a dicarboxylic acid By way of example of a dicarboxylic acid, mention may be made of acids having from 6 to 36, in particular those having 8 to 18 and in particular those having 10 to 12 carbon atoms.
• the diacids can be aliphatic, cycloaliphatic or aromatic diacids. Mention may be made, for example, of adipic acid, azelaic acid, suberic acid, sebacic acid, dodecanedioic acid HOOC-(CH2)IO-COOH, tetradecanedioic acid, isophthalic acid and terephthalic acid.
• Aliphatic diacids, in particular linear aliphatic diacids such as sebacic acid and dodecanedioic acid are preferred.
• diamines having 2 to 36, preferably 4 to 18 carbon atoms. They can be aromatic, aliphatic or cycloaliphatic.
• diamines having 2 to 36, preferably 4 to 18 carbon atoms. They can be aromatic, aliphatic or cycloaliphatic.
• diamines for example diamines. diacids, mention may be made more particularly of those resulting from the condensation of 1,6-hexamethylenediamine or 1,10-decamethylenediamine with sebacic acid or dodecanedioic acid.
• X conventionally represents the number of carbon atoms from diamine residues
• Y represents the number of carbon atoms from diacid residues.
• the polyamide is chosen from PA 9, PA 10, PA 11, PA 12, PA 610, PA 612, PA 614, PA 618, PA 1010, PA 1012.
• the polyamide in the composition according to the invention preferably has a melting point of less than or equal to 300°C.
• the polyamide has a melting point of less than or equal to 250°C, in particular 200°C, in particular 190°C.
• the polyamide in the pigmented powder composition according to the invention has an inherent viscosity greater than or equal to 0.7 (g/100 g) 1 .
• the viscosity of the polyamide in the composition is moreover less than or equal to 1.2 (g/100 g) 1 .
• its inherent viscosity is less than or equal to 1.1 g/100 g) 1 , in particular 1.0 (g/100 g) 1 , in particular 0.9 (g/100 g) 1 , more preferably 0.8 (g/100g) 1 .
• the composition becomes difficult to apply.
• a polyamide with a viscosity between 0.8 and 1.0 (g/100 g) 1 gives coatings with particularly interesting properties.
• the median diameter by volume Dv50 of the pigmented powdery composition according to the invention is from 30 to 200 ⁇ m, in particular from 30 to 100 ⁇ m, and in particular from 30 to 50 ⁇ m and even more preferably 32 to 38 ⁇ m Dv50 of the pigmented pulverulent composition may be 30 to 50 ⁇ m, or 50 to 80 ⁇ m, or 80 to 100 ⁇ m, or 100 to 130 ⁇ m, or 130 to 150 ⁇ m, or 150 to 180 ⁇ m, or 180 to 200 ⁇ m.
• the polyamide(s) are preferably present in a mass quantity, relative to the total mass of the pulverulent composition, of 40 to 99%, more preferentially of 50 to 95%, even more preferentially of 60 to 90%, for example of 40 to 45%, or 45 to 50%, or 50 to 55%, or 55 to 60%, or 60 to 65%, or 65 to 70%, or 70 to 75%, or 75 to 80%, or from 80 to 85%, or from 85 to 90%, or from 90% to 95%, or even from 95 to 99%.
• the pigmented powder composition according to the invention also comprises one or more pigments or dyes. These pigments or dyes are generally found in powder form.
• the pigment can in principle be freely chosen from the pigments used in the conventional manner. It can in particular be chosen from mineral pigments such as titanium dioxide, carbon black, cobalt oxide, nickel titanate, molybdenum disulphide, aluminum flakes, iron oxides, zinc, zinc phosphate, and organic pigments, such as phthalocyanine and anthraquinone derivatives.
• mineral pigments such as titanium dioxide, carbon black, cobalt oxide, nickel titanate, molybdenum disulphide, aluminum flakes, iron oxides, zinc, zinc phosphate, and organic pigments, such as phthalocyanine and anthraquinone derivatives.
• the dye can also be of any type known to those skilled in the art. Mention may be made in particular of azo dyes, anthraquinone dyes, dyes derived from indigo, triarylmethane dyes, chlorine dyes and polymethine dyes.
• the pigments and dyes are preferably present in a quantity by mass, relative to the total mass of the pulverulent composition, of 1 to 30%, more preferentially of 2 to 10%, even more preferentially of 3 to 5%, for example of 0 to 5%, or 5 to 10%, or 10 to 15%, or 15 to 20%, or 20 to 25%, or 25 to 30%.
• the pigmented powder composition according to the invention may also comprise, where appropriate, one or more additives chosen from the group consisting of anti-crater agents or spreading agents, reducing agents, antioxidants, reinforcing fillers, UV stabilizers , fluidizing agents, corrosion inhibitors, or mixtures thereof. These additives are advantageously in powder form.
• the reinforcing filler can be of any type suitable for the preparation of powders based on polyamides.
• the filler be selected from the group consisting of talc, calcium carbonates, manganese carbonates, potassium silicates, aluminum silicates, dolomite, magnesium carbonates, quartz, boron nitride, kaolin, wollastonite, titanium dioxide, glass beads, mica, carbon black, mixtures of quartz, mica and chlorite, feldspar and dispersed nanoscale fillers such as nanotubes of carbon and silica. It may also be fibers, in particular glass fibers and carbon fibers. Particularly preferably, the filler is calcium carbonate.
• the anti-crater and/or spreading agent can be of any type known to those skilled in the art.
• the anticrater and/or spreading agent is selected from the group consisting of polyacrylate derivatives.
• the UV stabilizer may be of any type known to those skilled in the art.
• the UV stabilizer is selected from the group consisting of resorcinol derivatives, benzotriazoles, phenyltriazines and salicylates.
• the antioxidants can be of any type known to those skilled in the art.
• the antioxidants are selected from the group consisting of copper iodide combined with potassium iodide, phenol derivatives and hindered amines.
• the fluidizing agent may be of any type known to those skilled in the art.
• the fluidizing agent is selected from the group consisting of aluminas and silicas.
• the corrosion inhibitors can be of any type known to those skilled in the art.
• the corrosion inhibitors are selected from the group consisting of phosphosilicates and borosilicates.
• the composition comprises less than 10% by weight, or even is essentially devoid of matting agent.
• additives are preferably present in a quantity by mass, relative to the total mass of the pulverulent composition, of 0 to 50%, more preferentially of 0 to 30%, even more preferentially of 0 to 5%, for example from 0 to 5%, or 5 to 10%, or 10 to 15%, or 15 to 20%, or 20 to 25%, or 25 to 30%, or 30 to 35%, or 35 to 40% , or 40 to 45%, or 45 to 50%.
• the pigmented powder composition according to the invention essentially consists, or consists, of one or more polyamides, one or more pigments, and optionally one or more additives as described above.
• the pigments and/or additives are mixed with the polyamide in the molten state.
• Such a mixture can be produced for example by compounding, in particular in an extruder.
• the pigments and/or additives thus added are then found in the form coated with polyamide.
• the invention also relates to a process for the preparation of a pigmented powder composition based on polyamide, comprising the steps of:
• step (iii) Grinding of the extrudate obtained in step (ii) into a powdery composition; and (iv) Polycondensation in solid phase of the pulverulent composition obtained in step (iii) until the polyamide has an inherent viscosity greater than 0.8 (g/100 g) 1 -
• the polyamide having an inherent viscosity of less than 0.6 (g/100 g) 1 used in step (i) can be obtained by polycondensation of one or more monomers as described above in the presence of water and the if necessary, a suitable catalyst.
• the monomer(s) can be chosen from amino acids such as aminocaproic acid, amino-7-heptanoic, amino-ll-undecanoic, amino-12-dodecanoic, and/or mixtures thereof, preferably l amino-11-undecanoic acid or a mixture thereof.
• diamine monomers and diacid monomers such as a mixture of diamine monomers such as hexamethylenediamine, decanediamine, dodecamethylenediamine, metaxylylenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylenediamine with diacid monomers such as isophthalic, terephthalic, adipic, azelaic, suberic, sebacic, dodecanedioic, tetradecanedioic acids, or a mixture thereof.
• diamine monomers such as hexamethylenediamine, decanediamine, dodecamethylenediamine, metaxylylenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylenediamine
• diacid monomers such as isophthalic, terephthalic, adipic, azelaic, suberic, sebacic, dodecanedioic, t
• the water is added in an amount of 10 to 40%, preferably 20 to 30% by weight relative to the total weight of the mixture. Water can be added to the mixture during the supply step, and/or during the polycondensation step.
• the catalyst may in particular be an acid based on phosphorus such as phosphoric acid and/or phosphorous acid.
• the polyamide synthesis reaction is known per se, and described in particular in the Nylon Plastics Handbook, Ed. Melvin I. Kohan, Hanser Publishers 1995 pages 17 to 27.
• the inherent viscosity of the polyamide used in step (i) of the process is less than 0.6 (g/100 g) 1 and preferably comprised in the range going from 0.25 to 0.55, preferably between 0.3 and 0.4 (g/100g) 1 .
• step (i) is carried out in a mixer under shear such as a single or twin screw extruder.
• the pigment(s) as well as any additives can be introduced into the mixer with the polyamide or subsequently. If the pigmented powder composition comprises several pigments, these can be added in the form of a masterbatch in order to facilitate homogenization.
• the masterbatch can in particular be made from the polyamide used in the composition.
• Extrusion step (ii) can be carried out through a pelletizing die to produce pellets.
• the volume median diameter Dv50 of the granules is advantageously within a range extending from 1 to 10 and in particular from 2 to 4 mm.
• the extrusion can be carried out through a die to a cooled rolling mill in which the mixture solidifies or using a calender. Then the solidified mixture can be fed to a crusher to produce flakes.
• These scales typically have an average size of 5x5x1 mm.
• Step (iii) is advantageously carried out in a mechanical mill, and at room temperature, in particular in an impact mill such as a hammer mill, a knife mill, a disk mill, or an air jet mill.
• a grinding aid such as silica, preferably pyrogenic, can be added to the polyamide before grinding.
• this step can be carried out in a grinder provided with an integrated selector.
• the particle size of the desired composition can be adjusted directly by adjusting the grinding speed, preferably, the adjustment of the grinding speed is made by means of a selector integrated into the grinder.
• step (iii) it may be advantageous to follow step (iii) with a step (iiia) of selecting the powdery composition obtained with a view to adjusting its particle size.
• the selection can be carried out for example by sieving and/or classification.
• the particle size of the powder composition can be adjusted by adjusting the grinding speed as well as the speed of the selector integrated into the grinder.
• the pulverulent composition resulting from stage (iii) if necessary has a median diameter by volume Dv50 of 30 to 200 ⁇ m, preferably of 30 to 50 ⁇ m in particular of 32 to 38 ⁇ m.
• the Dv50 of the pigmented powder composition can be from 30 to 50 ⁇ m, or from 50 to 80 ⁇ m, or from 80 to 100 ⁇ m, or from 100 to 130 ⁇ m, or from 130 to 150 ⁇ m, or from 150 to 180 ⁇ m, or 180 to 200 pm.
• Step (iv) of polycondensation in the solid phase can be carried out at a temperature above the glass transition temperature but below the melting temperature of the polyamide.
• the reaction is carried out under an inert atmosphere, for example under nitrogen or under vacuum.
• the reaction time required to reach the expected inherent viscosity depends on the temperature chosen; it can be established by simple routine tests.
• this step can be carried out in a dryer.
• the inherent viscosity of the polyamide in the powdery pigmented composition based on polyamide is greater than 0.7 (g/100 g) 1 .
• it is moreover less than 1.2 (g/100 g) 1 .
• its inherent viscosity is less than or equal to 1.1 g/100 g) 1 , in particular 1.0 (g/100 g) 1 , in particular 0.9 (g/100 g) 1 , still preferred 0, 8 (g/100g) 1 .
• the pigmented powder composition based on polyamide according to the invention is especially useful for coating substrates, especially metallic ones.
• the invention therefore relates to the use of the pigmented powder composition based on polyamide as described above for coating a substrate.
• metal substrate is meant a substrate which comprises, consists essentially of, or consists of, one or more metals.
• the metal substrate can be of any type.
• the metal substrate is a piece of plain or galvanized steel, aluminum or aluminum alloy.
• the metal substrate Before coating, the metal substrate may have undergone one or more of the surface treatments well known to those skilled in the art, such as coarse degreasing, alkaline degreasing, brushing, shot-blasting or sandblasting, fine degreasing, hot rinsing, phosphating degreasing, iron/zinc/tri-cation phosphating, chromating, cold rinsing and chromic rinsing.
• the pigmented powder composition can be used for coating treated or untreated metal substrates.
• the substrate intended to be coated is made of degreased, smooth or shot-blasted steel, degreased phosphated steel, iron or zinc phosphated steel, Sendzimir galvanized steel, electrogalvanized steel, hot-dip galvanized steel, cataphoresis-treated steel, chromated steel, anodized steel, sandblasted with corundum, degreased aluminum, smooth or shot-blasted aluminum, chromated aluminum, cast iron or any other metal alloy.
• the substrate can be coated in whole or in part.
• the coating formed on the substrate is a film 100 to 550 ⁇ m thick, more preferably 100 to 300 ⁇ m thick.
• the film has a thickness of 100 to 150 ⁇ m, or 150 to 200 ⁇ m, or 200 to 250 ⁇ m, or 250 to 300 ⁇ m, or 300 to 350 ⁇ m, or 350 to 400 ⁇ m. pm, or from 400 to 450 pm, or from 450 to 500 pm, or from 500 to 550 pm.
• the coating on the substrate has an inherent viscosity greater than or equal to 0.7 (g/100 g) 1 .
• the inherent viscosity of the coating may be different from that of the powder composition used to form it.
• the inherent viscosity of the coating can be higher due to a resumption of polycondensation under the conditions of formation of the coating.
• the coating on the substrate has an inherent viscosity greater than or equal to 0.8, greater than or equal to 0.85, or greater than or equal to 0.9, or greater than or equal to 0.95, or greater than or equal to 1.05, or greater than or equal to 1, or greater than or equal to 1.1, or greater than or equal to 1.15, or greater than or equal to 1.2, or greater than or equal to 1.25 , or greater than or equal to 1.3.
• the inherent viscosity is expressed in (g/100 g)-1.
• a subject of the invention is also a process for coating a substrate comprising the following steps: bringing the substrate into contact with the pigmented pulverulent composition based on polyamide as described above; and melting the powder composition under the effect of heat.
• the pigmented powder composition can be applied to or brought into contact with a substrate using numerous techniques well known to those skilled in the art.
• the coating is produced by electrostatic spraying or by hot powdering.
• the coating can be made by electrostatic spraying.
• the step of bringing the substrate into contact with the pigmented pulverulent composition based on polyamide can then comprise the steps of: electrical charging of the pulverulent composition; spraying the electrically charged powder composition onto the substrate; and heating of the substrate to be coated covered with powder composition to a temperature above the melting point of the polyamide.
• Electrostatic spray coating consists of depositing electrostatically charged powder particles on a substrate, in particular at room temperature.
• the powdery composition may be electrostatically charged as it passes through the nozzle of spray equipment.
• the composition thus charged can then be sprayed onto the substrate to be coated which is connected to a zero potential.
• the coated substrate can then be placed in an oven at a temperature to fuse the composition into a film.
• the powder projection equipment can be of any type, for example an electrostatic gun which charges the powder by Corona effect and/or by triboelectrification.
• the nozzle is brought to a high potential of between ten and a hundred kilovolts, of negative or positive polarity.
• the flow rate of powder in the projection equipment is 10 to 200 g/min, and more preferably, 50 to 120 g/min.
• the temperature of electrostatic application of the powder is from 15 to 25°C.
• the residence time of the substrate in the oven is 3 to 15 minutes.
• the heating temperature of the powder-coated substrate can be at least 30°C higher, preferably 30 to 60°C higher than the melting temperature of the polyamide. The substrate can then be cooled, for example, to room temperature.
• the coating of the substrate is carried out by hot powdering.
• the step of bringing the substrate into contact with the pigmented powder composition then comprises the steps of: heating the substrate to a temperature above the melting temperature of the polyamide; spraying the pigmented powder composition onto the substrate.
• the substrate heating temperature may be as described above in connection with fluidized bed dip coating.
• the substrate can then be cooled, for example, to room temperature.
• the sprayed composition may or may not be electrostatically charged.
• the invention relates to an object comprising a substrate covered with a coating capable of being obtained by melting the powder composition as described above.
• the coating gives the object effective anti-corrosion and anti-abrasive protection.
• This object is preferably intended: for the transfer of fluids, in particular in the form of piping, accessories, pumps or valves; automotive, in particular in the form of a splined shaft, sliding door rail or springs, in particular of the truck shock absorber type or automobile seats; wire articles, in particular in the form of dishwasher baskets or springs.
• FIG. 1 represents a diagram of the process for recycling the powder of examples 1 to 4 used to manufacture films
• FIG. 2 represents a semi-logarithmic diagram of the particle size distribution by volume (fraction of volume as a function of size) of a powder according to example 1, measured using a Malvern Insitec laser particle sizer (solid line: virgin powder ; -o-: powder recycled once; - ⁇ - powder recycled twice; -0- powder recycled three times);
• FIG. 3 represents a semi-logarithmic diagram of the particle size distribution by volume (fraction of volume as a function of size) of a powder according to example 2, measured by means of a Malvern Insitec laser particle sizer (solid line: virgin powder ; -o-: powder recycled once; - ⁇ - powder recycled twice; -0- powder recycled three times);
• FIG. 4 represents a semi-logarithmic diagram of the particle size distribution by volume (fraction of volume as a function of size) of a powder according to example 3, measured by means of a Malvern Insitec laser particle sizer (solid line: virgin powder; -o-: powder recycled once; powder recycled twice; -0- powder recycled three times); and
• FIG. 5 represents a semi-logarithmic diagram of the particle size distribution by volume (fraction of volume as a function of size) of a powder according to Example 4, measured using a Malvern Insitec laser particle sizer (solid line: virgin powder -o-: powder recycled once; powder recycled twice; -0- powder recycled three times).
• a pigmented powdery composition based on polyamide was manufactured according to the following process.
• prepolymer from 1.2 kg of amino-ll-undecanoic acid in the presence of 0.5 kg of water, 5 g of hypophosphorous acid and 9.8 g of phosphoric acid.
• the mixture is heated to a temperature of 190° C. in 2 hours with stirring as soon as the temperature reaches 160° C. or the pressure exceeds 8.5 bars.
• P constant pressure
• the molten prepolymer is extruded by means of a twin-screw extruder.
• the mixture is then cooled using two steel rollers with circulation of cold water to be solidified, cooled and crushed into scales.
• the prepolymer thus obtained having a viscosity of 0.35, and is mixed in a suitable container with a formulation of additives comprising antioxidants and spreading agents and a white pigment based on titanium dioxide in the proportions indicated. in Table 1 below.
• This mixture is introduced into a twin-screw extruder to be melted and intimately mixed and then extruded.
• the mixture is then cooled using two steel rollers with circulation of cold water to be solidified and cooled and then crushed into scales.
• the pigmented and additive prepolymer recovered in the form of flakes is then ground in a hammer mill equipped with an internal selector until a powder with a volume median diameter Dv50 is obtained, as measured according to ISO 9276 - parts 1 at 6, from 35pm.
• the ground powder is then subjected to solid phase polycondensation in a dryer at 140-152° C. under vacuum in order to increase the viscosity of the polyamide to 0.93 (g/100 g) 1 . ⁇ Table 1]
• a pigmented powdery composition based on polyamide was manufactured according to the following process.
• the prepolymer obtained according to the process indicated in Example 1 in the form of scales is ground in a hammer mill equipped with an internal selector until a powder is obtained having a median diameter by volume Dv50, as measured according to the standard ISO 9276 - parts 1 to 6, from 35pm.
• the ground prepolymer is then subjected to polycondensation in the solid phase at 140-152° C. under vacuum in order to increase the viscosity of the polyamide up to 0.93 (g/100 g) 1 .
• the pulverulent polyamide 11 is mixed in a rapid mixer of the Henschel type for 120 seconds at 1800 rpm, at room temperature (between 15 and 50° C.) with the formulation of additives and a white pigment based on carbon dioxide. titanium in the proportions indicated in Table 1 above.
• a pigmented powdery composition based on polyamide was manufactured according to the following process.
• prepolymer from 1.2 kg of amino-ll-undecanoic acid in the presence of 0.5 kg of water and 9.5 g of hypophosphorous acid.
• the mixture is heated to a temperature of 190° C. in 2 hours with stirring as soon as the temperature reaches 160° C. or the pressure exceeds 8.5 bars.
• P constant pressure
• the molten prepolymer is extruded by means of a twin-screw extruder.
• the mixture is then cooled using two steel rollers with circulation of cold water to be solidified, cooled and crushed into scales.
• the prepolymer thus obtained is mixed in a suitable container with a formulation of additives: a white pigment based on titanium dioxide, a blue pigment based on cobalt salt and a black pigment of the carbon black type in the proportions indicated in the table 1 above.
• This mixture is introduced into a twin-screw extruder to be melted and intimately mixed and then extruded.
• the mixture is then cooled using two steel rollers with circulation of cold water to be solidified and cooled and then crushed into scales.
• the pigmented and additive prepolymer recovered in the form of flakes is then ground in a hammer mill equipped with an internal selector until a powder with a volume median diameter Dv50 is obtained, as measured according to ISO 9276 - parts 1 at 6, from 35pm.
• the ground powder is then subjected to solid phase polycondensation in a dryer at 140-152° C. under vacuum in order to increase the viscosity of the polyamide to 0.93 (g/100 g) 1 .
• a pigmented powdery composition based on polyamide was manufactured according to the following process.
• the prepolymer obtained according to the process indicated in Example 1 in the form of scales is ground in a hammer mill equipped with an internal selector until a powder is obtained having a median diameter by volume Dv50, as measured according to the standard ISO 9276 - parts 1 to 6, from 35pm.
• the ground prepolymer is then subjected to polycondensation in the solid phase at 140-152° C. under vacuum in order to increase the viscosity of the polyamide up to 0.93 (g/100 g) 1 .
• the pulverulent polyamide 11 is mixed in a rapid mixer of the Henschel type for 120 seconds at 1800 rpm, at ambient temperature (between 15 and 50° C.) with a formulation of additives, a white pigment based on carbon dioxide titanium, a blue pigment based on cobalt salt and a black pigment of the carbon black type in the proportions indicated in Table 1 above.
• the virgin powder prepared in the previous examples was used to manufacture a first film (virgin film), then the excess powder was recovered three times. successively to manufacture recycling films, according to the procedure detailed in FIG.
• the virgin and recycled powders were characterized by measuring the particle size by volume (see Fig. 2 to 5) and the DvlO, Dv50 and Dv90, as measured according to ISO 9276 standard - parts 1 to 6, using a laser particle sizer (Malvern System Insitec) and the associated software (RT sizer).
• the particle size distributions obtained for the powders are illustrated in Figs. 2 to Fig. 5.
• the Dv10, Dv50 and Dv90 values recorded on these curves are collated in Table 2 below.
• the particle size curves (Fig. 2 to Fig. 5) also show that the maximum diameters of the powders of Examples 1 and 3 remain essentially stable around 200 ⁇ m, whereas they increase for the powders of Examples 2 and 4 to more 300 ⁇ m at the third recycle, indicative of particle agglomeration.
• the large particles have a greater tendency to detach from the metal support before passing through the oven, which makes the application of the powders of examples 2 and 4 more difficult.
• the coalescence of these particles is longer and therefore affects the film formation.
• the films were manufactured by applying the powder by means of an electrostatic gun (Corona positive, +35 to + 45 kV, 10 to 30 pA) on 3 mm thick steel metal plates treated with an anti-corona treatment. -adherent (silicone type coating), facilitating the subsequent detachment of the coating films.
• the metal plates thus coated with powder were then heat-treated (oven at 220° C. for 10 minutes), in order to melt the powder and obtain a film.
• the films are then peeled off from the substrates to be characterized in terms of appearance and mechanical properties.
• the films were manufactured by applying the powder by means of an electrostatic gun (Corona positive, +35 to + 45 kV, 10 to 30 pA) on 3 mm thick steel metal plates treated with an anti-corona treatment. -adherent (silicone type coating), facilitating the subsequent detachment of the coating films.
• the metal plates thus coated with powder were then heat-treated (oven at 220° C. for 10 minutes), in order to melt the powder and obtain a film.
• the films are then peeled off from the substrates to be characterized in terms of appearance and mechanical properties. The results of these measurements and evaluations are collated in Table 3 below.
• the films obtained with the powder of examples 1 and 3 have higher and more stable elongations at break as the recycling progresses compared to those obtained from the powders of examples 2 and 4.
• the initial elongation at break between the two types of film therefore increases with the number of recyclings.
• a better elongation at break is considered to reflect a better dispersion of the additives and pigments in the powder.
• the powders of Examples 1 and 3 therefore make it possible to obtain more homogeneous and more flexible films.

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