Classifications

• • 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
  • C08G69/04—Preparatory processes
  • C08G69/06—Solid state polycondensation
• • 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
  • C08G69/46—Post-polymerisation treatment
• • 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
  • C08G69/04—Preparatory processes
• • 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
  • 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
  • C08G69/14—Lactams
  • C08G69/16—Preparatory processes
• • 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
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• the present invention relates to a method for preparing a powder composition based on polyamide(s) with optimized yield.
• the invention also relates to the powder composition obtained and its use, in particular for the coating of metal substrates by dipping in a fluidized bed.
• a polyamide powder composition can be obtained via a cryogenic grinding process from a polymer in the form of granules, but the process is expensive and has a low yield.
• a polyamide powder composition can be obtained via a manufacturing process in which low-viscosity prepolymers are ground beforehand, followed by a solid-phase polycondensation step so that the polyamide powder reaches the viscosity desired.
• This type of process makes it possible to obtain a raw powder from prepolymers, which are easier to grind, compared to raw powder whose viscosity is generally higher.
• the raw powder as obtained has a relatively wide particle size distribution, and in particular has a large portion of fine particles.
• Fine particles are defined as particles with diameters generally 3 times less than the median diameter by volume (Dv50).
• Dv50 median diameter by volume
• the fine particles are those whose diameter is less than 40 ⁇ m.
• the flight of fine particles during the fluidization of the powder can represent approximately 8% in losses, and/or cause a change in the particle size distribution of the powder by the depletion of fine particles, degrading its applicability, namely making it difficult to control the thickness of the coating and making the quality of fluidization difficult to maintain constant.
• a screening step is often required to remove these fine particles from the powder composition before it is used in a dipping process. This step makes it possible to provide a powder with a narrow particle size by eliminating fine particles but generates a significant quantity of waste, namely unusable fine particles.
• a powder composition with bulk additives means a polymer-based powder composition comprising additives (such as pigments, antioxidants) obtained by a process of mixing in the melting (also called “compounding”), by which the additives are included in the powder particles.
• the object of the invention is to propose a process making it possible to reuse the undesirable fine particles, and thus to improve the yield of the preparation process.
• the invention also seeks to provide a powder composition of controlled and preferably tight particle size, which can be used in a fluidized bed dipping process.
• the invention relates firstly to a method for preparing a powder composition based on polyamide(s) (PA composition) having an inherent viscosity greater than or equal to 0.65 (g/100 g) -1 and less than or equal to 1.40 (g/100 g) -1 , comprising:
• composition (i) based on a polyamide prepolymer having a maximum inherent viscosity of 0.60 (g/100 g)' 1 , where appropriate, with mass additives;
• composition (ii) grinding composition (i) to obtain powder composition (ii);
• composition PA1 having an inherent viscosity greater than or equal to 0.65 (g/100 g) ⁇ 1 and less than or equal to 1.40 (g/100 g) ⁇ 1 , preferably composition PA1 being composition PA.
• the Dv50 of the pre-PAO composition is not satisfactory and the Dv50 of the pre-PA composition is that sought according to a desired final application.
• Composition (i) is in the form of a divided solid, preferably a coarse powder of sizes less than 1 mm.
• composition based on a polyamide prepolymer or a composition based on a polyamide means a composition comprising at least 50% by weight of polyamide or polyamide prepolymer, relative to the total weight of the composition.
• the pre-PAO composition has a Dv50 3 times lower than the Dv50 of the powder composition (ii).
• the pre-PAO composition has a Dv50 of less than 50 ⁇ m.
• the present invention makes it possible to reduce losses by recycling particles of unsatisfactory particle size, within the same manufacturing process when the recycling step occurs in the process for preparing the PA composition or else in a subsequent process of preparation of another composition based on polyamides.
• the process of the invention is particularly interesting for so-called fine or extra-fine prepolymer particles, typically those having a diameter of less than 50 ⁇ m, it goes without saying that all the prepolymers, whatever their particle size, preferably having a inherent viscosity less than 0.60 (g/100 g)' 1 , can be used in the recycling stage.
• the polyamide in the PA composition has a melting point of less than or equal to 300°C.
• the composition has a melting point less than or equal to 250°C, more preferably less than or equal to 200°C, for example less than or equal to 190°C.
• the polyamide in the PA composition according to the invention has an inherent viscosity greater than or equal to 0.65 (g/100 g) ⁇ 1 and less than or equal to 1.40 (g/100 g) ⁇ 1 .
• its inherent viscosity is greater than or equal to 0.70 g/100 g) -1 , in particular 0.75 g/100 g) -1 , in particular 0.80 (g/100 g) -1 and less than or equal to 1.10 (g/100 g) -1 , more preferably 1.05 (g/100 g) -1 , in particular 1.0 (g/100 g) -1 .
• the process of the present invention allows the fine particles to be removed and recycled during manufacture in order to reduce the amount of waste throughout the preparation and application process.
• the step of recycling the pre-PAO composition comprises:
• pre-PA1 composition “pre-PA1 composition”.
• water is added in an amount of 10 to 40%, preferably 20 to 30% by weight relative to the total weight of the mixture.
• the pre-PAO composition can comprise a polyamide prepolymer or a mixture of several polyamide prepolymers.
• the pre-PAO composition comprises a polyamide prepolymer.
• the pre-PAO composition consists of a polyamide prepolymer.
• the pre-PAO composition comprises at least 50% of polyamide(s) prepolymers and one or more additives.
• the inherent viscosity of the prepolymer of the polyamide(s) in the pre-PAO composition is less than 0.60 (g/100 g) -1 , typically comprised in the range going from 0.25 to 0.55, preferably between 0 30 and 0.50 (g/100 g) -1 , even more preferably between 0.40 and 0.50 (g/100 g) -1 .
• the inherent viscosity of the prepolymer of the polyamide(s) in the pre-PA1 composition is less than 0.60 (g/100 g) -1 , typically comprised in the range going from 0.25 to 0.55, preferably between 0 30 and 0.50 (g/100 g) -1 , even more preferably between 0.40 and 0.50 (g/100 g) -1 .
• the pre-PAO composition is a composition based on a prepolymer of PA 11, PA 12, PA 1010, PA 1012, PA 6, PA 610, PA 612, PA 614, PA 618, PA 8, PA 9, PA 10, PA 13, PA 14 and mixtures thereof, preferably a composition consisting of PA 11 polyamide prepolymers.
• the catalyst is chosen from phosphoric acid and/or hypophosphorous acid.
• the catalyst is typically in the form of an aqueous solution.
• one or more monomers are chosen from amino acids, lactams, preferably chosen from aminocaproic acid, amino-7-heptanoic acid, amino-8-octanoic acid, amino-9-nonanoic acid, amino-10-decanoic acid, amino-11-undecanoic acid, amino-12-dodecanoic acid, amino-13-tridecanoic acid, amino- 14-tetradecanoic acid and/or mixtures thereof, preferably amino-11-undecanoic acid.
• one or more monomers is a mixture of diamine monomers and diacid monomers, preferably, a mixture of diamine monomers such as hexamethylenediamine, decanediamine, dodecamethylenediamine, metaxylylenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylene diamine with diacid monomers such as isophthalic, terephthalic, adipic, azelaic, suberic, sebacic, dodecanedioic acids, tetradecanedioic acid, and/or mixtures thereof.
• diamine monomers such as hexamethylenediamine, decanediamine, dodecamethylenediamine, metaxylylenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylene diamine
• diacid monomers such as isophthalic, terephthalic, adipic, azelaic, suberic, sebacic,
• a monomer corresponding to the monomer unit of the polyamide (PA) having an inherent viscosity of less than 0.60 is introduced.
• PA polyamide
• a monomer different from the monomer unit of the polyamide For example, one can provide a mixture of amino-12-dodecanoic as monomers and a PAO-composition based on polyamide 11 prepolymer to obtain a pre-PA1 composition based on copolyamide 11/12.
• the solid phase polycondensation step is carried out at a temperature above the glass transition temperature and 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.
• a particular process is thus proposed, which comprises a step where the prepolymers, in particular those having a fine particle size, are mixed with the monomers as reactants participating in the polycondensation reaction.
• step (iv) may comprise all or at least one of the following steps, successively:
• the cooled pre-PA1 composition is passed through a granulator or a grinder, which reduces it to a coarse powder, typically with an average diameter of less than 5 mm, before the following stages.
• (iv-4) optionally a step of mixing in the molten state so as to add additives, such as pigments, antioxidants, to the pre-PA1 composition, whereby the mass-additive pre-PA1 composition is obtained .
• the melt-mixing step consists of melt-mixing the molten polycondensation product with additives, for example, by means of two screws in a heated barrel. The mixture is then extruded through a die to a cooled rolling mill in which the mixture solidifies or using a calender.
• the temperature applied during the mixing step should slightly exceed the melting temperature of the prepolymer. Typically, the temperature applied is at most 5° C. higher than the melting temperature of the prepolymers.
• the residence time is less than 1 minute.
• a pre-PAO composition preferably those having a fine particle size, typically less than 40 ⁇ m.
• the mass-additive pre-PA1 composition is passed through a granulator or a grinder, which reduces it to a coarse powder, typically with an average diameter of less than 5 mm, before the following steps.
• the grinding is preferably a mechanical grinding, carried out at room temperature.
• the grinding can be carried out in an impact mill, for example a hammer mill, a knife mill, a disk mill, or an air jet mill, preferably equipped with an internal selector.
• the particle size of the pre-PA1 composition is adjusted directly by adjusting the grinding speed, preferably, the adjustment is also carried out by means of a selector integrated into the grinder.
• the optional selection step makes it possible to separate the ground pre-PA1 composition into at least 2 compositions, one of which has a desired Dv 50.
• the composition whose Dv50 is unsatisfactory can be recycled again in the process of the invention.
• the process of the invention makes it possible to recycle unusable materials several times if necessary, making it possible to minimize losses during manufacture.
• the process of the invention may comprise:
• (v) a step of increasing the viscosity of the pre-PA1 composition obtained after one or more steps described above, optionally mixed with the pre-PA composition, until the desired final viscosity of the composition of the powder based on polyamide(s), preferably produced by polycondensation in the solid phase in a dryer.
• step (vi) optionally a step of dry mixing the composition of the powder based on polyamide(s) with additives, such as pigments, antioxidants, the additives preferably having a particle size similar to that of the composition of the powder based on polyamide(s).
• additives such as pigments, antioxidants, the additives preferably having a particle size similar to that of the composition of the powder based on polyamide(s).
• the step of recycling (iv) of the pre-PAO composition comprises a step of mixing in the molten state (also called “compounding") of the pre-PAO composition, if necessary , with bulk additives, as defined above, optionally mixed with a composition of polyamide prepolymers and/or additives, under conditions such that the polycondensation in the melt phase during this step is limited, whereby one obtains a composition based on prepolymer(s) (pre-PA1 composition) with bulk additives.
• the melt-mixing step consists of melt-mixing the pre-PAO composition, optionally with a polyamide prepolymer composition and/or additives, for example, by means of two screws within heated sleeves.
• the mixture is then extruded through a die to a cooled rolling mill in which the mixture solidifies or using a calender.
• the temperature applied during the mixing step should slightly exceed the melting temperature of the prepolymer. Typically, the temperature applied is at most 5°C higher than the melting temperature of the prepolymers.
• the residence time is less than 1 minute.
• the pre-PAT composition can be passed through a granulator or a grinder, which reduces it to a coarse powder, typically with an average diameter of less than 5 mm,
• the recycling step (iv) comprises a step of grinding and optionally of selecting the cooled pre-PAT composition.
• Grinding is a mechanical grinding, which can be cryogenic, or carried out at room temperature
• the grinding can be carried out in an impact mill, for example a hammer mill, a knife mill, a disk mill, or an air jet mill, preferably equipped with an internal selector.
• an impact mill for example a hammer mill, a knife mill, a disk mill, or an air jet mill, preferably equipped with an internal selector.
• the particle size of the pre-PAT composition is set directly by adjusting the grinding speed, preferably by means of a selector integrated into the mill.
• the optional step of selection makes it possible to separate the ground pre-PAT composition into at least 2 compositions, one of which has a desired Dv 50.
• the composition whose Dv50 is unsatisfactory can be recycled again in the process of the invention.
• the process of the invention makes it possible to recycle unusable materials several times if necessary, making it possible to minimize losses during manufacture.
• the method for preparing the polyamide-based powder composition may comprise all or at least one of steps (v) and (vi) as described below.
• the present invention thus makes it possible to reuse the prepolymers or a composition comprising the prepolymers having an unsatisfactory particle size as reagents in a manufacturing process, to greatly limit the losses of raw materials, which can range from production to end use, in particular for application in fluidized bed dip coating.
• the present invention also proposes a powder composition based on polyamide(s) (PA) with a controlled particle size, preferably tighter and more uniform, while reducing the losses of materials during its preparation process.
• PA polyamide(s)
• the invention relates to a powder composition based on polyamide(s) wholly or partly resulting from a process as described above in which the polyamide has an inherent viscosity of 0.65 to 1.40 ( g/100 g) -1 , preferably from 0.70 to 1.10 (g/100 g) -1 , even more preferably from 0.80 to 1.00 (g/100 g) -1 and preferably having a median diameter by volume Dv50 of between 80 and 130 ⁇ m, even more preferably between 90 and 120 ⁇ m, or even between 100 and 110 ⁇ m.
• the powder composition comprises additives, preferably is added in bulk.
• the invention also relates to the use of the composition as defined above in a coating process on a metal substrate by dipping in a fluidized bed.
• composition is particularly suitable for coatings prepared by a fluidized bed dipping process, the composition can also be used in other fields.
• the invention relates to the use of the composition as defined above in paints, anti-corrosion compositions, additives for paper, powder agglomeration technologies by melting or sintering caused by radiation to manufacture objects , electrophoresis gels, multilayer composite materials, packaging industry, toys, textiles, automotive and/or electronics.
• prepolymer means a prepolymer whose inherent viscosity is less than 0.60 (g/100 g)' 1 .
• 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 additives 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 11 357-3 in 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 11 357-2 using a heating rate of 20°C/min.
• 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 Dv10 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 (Sympatec Helos). Software (Fraunhofer) then makes it possible to obtain the volumetric distribution of a powder and to deduce the Dv10, the Dv50 and the Dv90.
• the polyamide can be aliphatic, semi-aromatic and cycloaliphatic.
• the polyamide can be chosen from a homopolyamide, a copolyamide, and mixtures thereof.
• It can also be a mixture of polyamide and at least one other polymer, the polyamide forming the matrix and the other polymer(s) forming the dispersed phase.
• polyamide within the meaning of the invention means the condensation products:
• amino acid monomers such as aminocaproic acid, aminocaproic acid, amino-7-heptanoic acid, amino-8-octanoic acid, amino-9-nonanoic acid, amino -10-decanoic acid, amino-11-undecanoic acid, amino-12-dodecanoic acid, amino-13-tridecanoic acid, amino-14-tetradecanoic acid of one or more lactam monomers such as caprolactam , oenantholactam and lauryllactam;
• diamine monomers such as hexamethylenediamine, decanediamine, dodecamethylenediamine, metaxylylenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylenediamine with diacids such as isophthalic, terephthalic, adipic, azelaic acids, suberic, sebacic, dodecanedioic and tetradecanedioic.
• diamine monomers such as hexamethylenediamine, decanediamine, dodecamethylenediamine, metaxylylenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylenediamine with diacids such as isophthalic, terephthalic, adipic, azelaic acids, suberic, sebacic, dodecanedioic and tetradecanedioic.
• the polyamide can be a copolyamide. Mention may be made of the copolyamides resulting from the condensation of at least two different monomers, for example of at least two different alpha omega aminocarboxylic acids or of two different lactams or of a lactam and an alpha omega aminocarboxylic acid of a number of different carbon. Mention may also be made of the copolyamides resulting from the condensation of at least one alpha-omega aminocarboxylic acid (or a lactam), at least one diamine and at least one dicarboxylic acid.
• copolyamides resulting from the condensation of an aliphatic diamine with an aliphatic dicarboxylic acid and at least one other monomer chosen from aliphatic diamines different from the previous one and aliphatic diacids different from the previous one.
• a repeating unit of the polyamide consists of the association of a diacid with a diamine is particular. It is considered that it is the association of a diamine and a diacid, that is to say the couple "diaminediacid”, also called “XY”, in equimolar quantity which corresponds to the monomer. This is explained by the fact that individually, the diacid or the diamine is only a structural unit, which is not enough on its own to form a polymer.
• diamine X By way of example of diamine X, mention may be made of aliphatic diamines having from 6 to 12 atoms, the diamine X possibly also being aryl and/or saturated cyclic. Examples include hexamethylenediamine, piperazine, tetramethylenediamine, octamethylenediamine, decamethylenediamine, dodecamethylenediamine, 1,5 diaminohexane, 2,2,4-trimethyl-1,6 -diamino-hexane, diamine polyols, isophorone diamine (IPD), methyl pentamethylenediamine (MPMD), bis(aminocyclohexyl) methane (BACM), bis(3-methyl-4 aminocyclohexyl) methane (BMACM), metaxylyenediamine, bis-p aminocyclohexylmethane and trimethylhexamethylene diamine.
• IPD isophorone diamine
• MPMD methyl pen
• diacid (or dicarboxylic acid) Y By way of example of diacid (or dicarboxylic acid) Y, mention may be made of acids having between 4 and 18 carbon atoms. Mention may be made, for example, of adipic acid, sebacic acid, azelaic acid, suberic acid, dodecanedioic acid, tetradecanedioic acid, isophthalic acid, butanedioic acid, 1 ,4 cyclohexyldicarboxylic acid, terephthalic acid, sodium or lithium salt of 5-sulfoisophthalic acid, dimerized fatty acids (these dimerized fatty acids have a dimer content of at least 98% and are preferably hydrogenated).
• lactam or amino acid monomers are said to be of the “Z” type:
• lactams By way of example of lactams, mention may be made of those having from 3 to 12 carbon atoms on the main cycle and which may be substituted. Mention may be made, for example, of P,p-dimethylpropriolactam, ⁇ , ⁇ -dimethylpropriolactam, amylolactam, caprolactam, capryllactam, oenantholactam, 2-pyrrolidone and lauryllactam.
• alpha-omega amino acids such as aminocaproic, amino-7-heptanoic, amino-11-undecanoic, n-heptyl-11-aminoundecanoic and amino-12-dodecanoic acids.
• the polyamide (PA) according to the invention comprises at least one polyamide or one polyamide block chosen from polyamides and copolyamides comprising at least one of the following monomers: 46, 4T, 54, 59, 510, 512, 513, 514, 516, 518, 536, 6, 64, 66, 69, 610, 612, 613, 614, 616, 618, 636, 6T, 9, 10, 104, 109, 1010, 1012, 1013, 1014, and mixtures thereof.
• the polyamides (PA) comprise at least one polyamide chosen from polyamides and copolyamides comprising at least one of the following XY or Z monomers: 59, 510, 512, 514, 6, 69, 610, 612, 614, 109, 1010, 1012, 1014, 10T, 11, 12, 129, 1210, 1212, 1214, 12T, MXD6, MXD10, MXD12, MXD14, and mixtures thereof; in particular chosen from PA 11, PA 12, PA 1010, PA 1012, PA 6, PA 610, PA 612, PA 614, PA 618 and mixtures thereof.
• copolyamides examples include PA 6/12, PA 6/66, PA 6/12/66, PA 6/69/11/12, PA 6/66/11/12, PA 69/ 12, PA 11/10T.
• 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. Mention may also be made of one or more additives which are chosen from the group consisting of anti-crater agents or spreading agents, reducing agents, antioxidants, reinforcing fillers, UV stabilizers, fluidizing agents, corrosion, or mixtures thereof.
• 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 additives are preferably present in a quantity by mass, relative to the total mass of the composition, of 1 to 30%, more preferably of 2 to 10%, even more preferably of 3 to 5%, for example from 0 to 5 %, or from 5 to 10%, or from 10 to 15%, or from 15 to 20%, or from 20 to 25%, or from 25 to 30%.
• 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 carbon nanotubes and silica.
• the filler is calcium carbonate.
• the fillers are preferably present in a quantity by mass, relative to the total mass of the composition, of 0 to 50%, more preferably of 0 to 10%, even more preferably of 0 to 5%, for example from 0 to 5 %, or from 5 to 10%, or from 10 to 15%, or from 15 to 20%, or from 20 to 25%, or from 25 to 30%.
• pre-PAO powder polyamide 11 prepolymer
• a monitoring of the amount of vapor removed is carried out until a certain amount of vapor removed, which corresponds to the desired viscosity for the prepolymer.
• the prepolymer of viscosity 0.40 is then drained. At the level of the drain valve, the prepolymer is still in fusion then it cools when there is contact between two cold metal rollers and becomes solidified.
• the solidified prepolymer is then passed through a granulator or a grinder, which reduces it to coarse powder with an average diameter of less than 5 mm. The experiment was repeated 3 times to obtain prepolymers with a viscosity of 0.39/0.42/0.40 (g/100 g)' 1 .
• Example 1.1 The coarse powder obtained in Example 1.1 is ground in a hammer mill equipped with an internal selector. The crushed raw powder thus obtained is separated in a separator cyclone to obtain 2 powders:
• the freeze-ground powder has a much greater proportion of fine particles with a size of less than 50 ⁇ m than the powder of the present invention—approximately 5% for the freeze-ground powder against less than 0.3% for the powder of the present invention.
• the freeze-ground powder also has a much higher proportion of large particles with a size greater than 300 ⁇ m - about 8% for the freeze-ground powder against about 1% for the powder of the present invention.
• the powder of the present invention has two main advantages for use in fluidized bed dipping:
• the low proportion of particles > 250 pm makes it possible to reduce the fluidization speed (see example 4), -
• the low proportion of fines ⁇ 50 ⁇ m, as well as a low fluidization speed makes it possible to limit the flights of fines.
• the powder of the present invention makes it possible to limit this loss to less than 0.1%.
• the [Fig. 2] presents the evolutions of particle size caused by fluidization:
• the evolution of the particle size of a freeze-ground powder is significant, whereas the powder of the present invention is stable. Therefore, the application quality of the present invention is stable.
• This stability in the application quality of the product makes it possible to reuse the powder of the present invention after numerous dipping applications, where the freeze-ground powder must be renewed with virgin powder.
• the present invention makes it possible to reduce the waste rate induced by this product renewal by around 5%.
• FIG. 3 presents the delta P profile as a function of air velocity for a powder bed.
• the "virgin" freeze-ground powder that is to say for a first fluidization, shows that the minimum fluidization speed is approximately 1.8 m/s, where the powder of the present invention requires 1.0 m/ s for its fluidization.

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• 2020
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• 2021
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