Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/141—Processes of additive manufacturing using only solid materials
  • B29C64/153—Processes of additive manufacturing using only solid materials using layers of powder being selectively joined, e.g. by selective laser sintering or melting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/10—Processes of additive manufacturing
  • B29C64/141—Processes of additive manufacturing using only solid materials
• • 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
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/08—Heat treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/20—Apparatus for additive manufacturing; Details thereof or accessories therefor
  • B29C64/264—Arrangements for irradiation
  • B29C64/268—Arrangements for irradiation using laser beams; using electron beams [EB]
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—Additive manufacturing, i.e. manufacturing of three-dimensional [3D] objects by additive deposition, additive agglomeration or additive layering, e.g. by 3D printing, stereolithography or selective laser sintering
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/386—Data acquisition or data processing for additive manufacturing
  • B29C64/393—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C67/00—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00
  • B29C67/24—Shaping techniques not covered by groups B29C39/00 - B29C65/00, B29C70/00 or B29C73/00 characterised by the choice of material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C71/00—After-treatment of articles without altering their shape; Apparatus therefor
  • B29C71/02—Thermal after-treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/34—Layered products comprising a layer of synthetic resin comprising polyamides
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y50/00—Data acquisition or data processing for additive manufacturing
  • B33Y50/02—Data acquisition or data processing for additive manufacturing for controlling or regulating additive manufacturing processes
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
  • B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
• • 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
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
  • C08J7/05—Forming flame retardant coatings or fire resistant coatings
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2077/00—Use of PA, i.e. polyamides, e.g. polyesteramides or derivatives thereof, as moulding material
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2009/00—Layered products
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y80/00—Products made by additive manufacturing
• • 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
  • C08J2377/06—Polyamides derived from polyamines and polycarboxylic 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
  • C08J2477/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
  • C08J2477/06—Polyamides derived from polyamines and polycarboxylic acids
• • 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
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
  • Y10T428/00—Stock material or miscellaneous articles
  • Y10T428/31504—Composite [nonstructural laminate]
  • Y10T428/31725—Of polyamide
  • Y10T428/31728—Next to second layer of polyamide

Definitions

• the present invention relates to a method comprising a step of heat treating a polyamide-based powder to reduce the difference between the initial crystal rearrangement temperature and the final crystal rearrangement temperature.
• the invention also relates to articles obtained by the use of powders having undergone this treatment, in particular by selective melting of polymer powder layers, particularly rapid prototyping by solid-phase sintering using a laser.
• the process for manufacturing articles by selective melting of polymer powder layers is a process that makes it possible to obtain complex shape parts without tools and without machining, from a three-dimensional image of the article to be produced.
• Thermoplastic polymers are generally used for this purpose.
• Generalities on rapid prototyping by laser sintering are mentioned in US6136948 and WO96 / 06881, US20040138363.
• the technology for agglomerating polyamide powders under electromagnetic radiation is used to manufacture three-dimensional objects for various applications, including prototypes and models.
• the decrease in the difference between the final temperature of the crystal rearrangement and the initial temperature of the crystal rearrangement, also called Tfr-Tir, is a parameter influencing the properties of the polyamide powders, in particular with a view to their use in the production of articles by selective melting of (co) polyamide powder layers, in particular of type 6 or 66.
• a reduction of this difference may make it possible to improve the characteristics of the powder, in particular to reduce or even reduce avoiding the presence of cracks and / or clumps on the surface of the powder bed during the manufacture of articles, improving its sinterability, and / or the flowability of the powder, as well as improving the article obtained by laser sintering in particular in terms of surface quality.
• the Applicant has just developed a method for reducing the difference between the final crystalline rearrangement temperature and the initial crystalline rearrangement temperature, symbolized by the expression "Tfr-Tir", of a (co) polyamide powder. Said method may make it possible to improve the properties of said powder, especially when it is used to produce articles by selective melting of powder layers.
• the phenomenon of crystalline rearrangement also called “cold crystallization”, for example in the French patent application FR 10 60345, published under the number FR2968664, corresponds to an exothermic process resulting from the rearrangement of the amorphous zones of the material in crystalline zones. It appears at a temperature below the melting temperature of the polymer.
• DSC Different Scanning Calorimetry
• the subject of the invention is a process for heat treatment of a (co) polyamide composition, especially in the form of a powder, comprising at least the following stages:
• said (co) polyamide is semi-crystalline.
• the temperatures Tir and Tfr are measured by a modulated DSC method P which consists of measuring the shots and the Tfrs by differential modulated calorimetric analysis in which: a) the composition, and in particular the (co) polyamide (s), is maintained at a temperature of 25 ° C. for 5 minutes,
• a modulated temperature rise is carried out at a rate of 3 ° C / min up to 250 ° C with a sinusoidal amplitude of 0.48 ° C and a period of 1 minute, then a cooling, at a rate of 3 ° C / min to 25 ° C and the signal is recorded.
• the method P is as described below, and comprises 4 steps:
• the nitrogen used is of analytical quality. It will be used for all measurements, according to the recommendations of the device manufacturer.
• this method can make it possible to determine the cold crystallization enthalpy AHcf in Joule / gram which is given directly by the data processing software from the area A, as described in the French patent application whose filing number is 10 60345.
• the composition may be brought to a temperature ranging from min-28 ° C. to min-2 ° C., in particular ranging from min-25 ° C. to min-5 ° C., in particular from min-22 ° C. to Tmin-10 ° C, or even about Tmin-20 ° C.
• the composition is not brought to a temperature greater than or equal to its softening point, in particular the composition reaches a maximum temperature equal to the softening temperature -2 ° C.
• This softening temperature can be measured by Dynamic Mechanical Analysis (DMA).
• DMA Dynamic Mechanical Analysis
• the process involves heating to bring the composition to a temperature lower than the lowest melting temperature, or Tfmin, and higher than the temperature Tfmin-30 ° C, and in particular at a temperature as defined above, for at least 10 minutes. More particularly, the composition is brought to such a temperature for a period ranging from 10 minutes to 120 minutes, especially from 10 to 60 minutes, or even 15 to 45 minutes.
• the composition is brought to a temperature below X and greater than Y” is meant that the entire composition reaches and remains at a temperature in the range, particularly at the heart of the composition.
• the cooling is relatively slow, in particular it is obtained by simply stopping the heating.
• the melting point corresponds to the end temperature of the endothermic peak determined by DSC.
• this melting temperature is measured according to method P in which steps 1 to 3 are as described above, and step 4 'of determining the melting temperature Tf is as follows:
• the temperature corresponding to the top of the peak is the melting temperature of the material.
• the (co) polyamide (s) of the composition present (s) have a single melting point.
• the temperature difference between the highest and the lowest melting point may not exceed 15 ° C, in particular less than or equal to 10 ° C, or even lower than or equal to 5 ° C.
• the powder obtained by the process may have Tfr-Tir decreased by at least 15%, especially by at least 25%, or even at least 30% relative to the Tfr-Tir value of the composition before treatment.
• Said composition may comprise a (co) polyamide content ranging from 50 to 100% by weight relative to the total weight of the composition. More particularly, this content may range from 60 to 100% by weight, especially from 75 to 100% by weight, and even from 90 to 100% by weight relative to the total weight of the composition.
• the composition comprises a content of (co) polyamide ranging from 95 to 100% by weight relative to the total weight of the composition.
• the composition may comprise one or more (co) polyamide (s).
• the content of one of these may be greater than 80% by weight, in particular 90% by weight relative to the total weight of the composition.
• the composition comprises two, three or four (co) polyamides.
• polyamides may not be in the form of a mixture of diacid-regulated polyamide and diamine-regulated polyamide and / or diacid-regulated copolyamide and of diamine-regulated copolyamide, in particular as defined in document US20060071359.
• the composition comprises a single (co) polyamide.
• the composition may also consist solely of (co) polyamide, and especially of 1, 2, 3 or 4 (co) polyamides, in particular it consists of a single (co) polyamide.
• the polyamides may be chosen from the group comprising polyamides obtained by polycondensation of at least one linear aliphatic dicarboxylic acid with an aliphatic or cyclic diamine or between at least one aromatic dicarboxylic acid and an aliphatic or aromatic diamine, the polyamides obtained by polycondensation of at least one amino acid or lactam on itself, or their mixture and (co) polyamides.
• Semi-crystalline polyamides are particularly preferred.
• Linear polyamides are also preferred.
• the polyamide may be chosen from the group comprising polyamides obtained by polycondensation of at least one aliphatic dicarboxylic acid with an aliphatic or cyclic diamine such as PA 6.6, PA 6.10, PA 6.12, PA 10.10, PA 12.12, PA 4.6, MXD 6. or between at least one aromatic dicarboxylic acid and an aliphatic or aromatic diamine such as polyterephthalamides, polyisophthalamides, polyaramids, or their mixture and (co) polyamides, especially PA 6.6 / 6. T.
• the polyamide of the invention may also be chosen from polyamides obtained by polycondensation of at least one amino acid or lactam on itself, the amino acid being able to be generated by the hydrolytic opening of a lactam ring such as that, for example PA 6, PA 7, PA 9, PA 1 1, PA 12, PA 13 or their mixture and (co) polyamides.
• the polyamide of the invention may also be chosen from the group of polyamides obtained by polycondensation of diacid, diamine and amino acid, such as copolyamides PA 6.6 / 6. Linear polyamides are especially preferred.
• the composition comprises a total content of PA1 1 and PA12 less than or equal to 10% by weight relative to the total weight of (co) polyamide present in the composition, and most particularly the composition is devoid of PA1 1 and / or PA12.
• the composition may comprise a copolyamide content ranging from 50 to 100% by weight, in particular from 60 to 95% by weight relative to the total weight of polyamide, or even with respect to the total weight of thermoplastic polymer, or even with respect to the total weight of the composition.
• the composition comprises, as polyamide or even as thermoplastic polymer, only one or more copolyamide (s), in particular such as described in the present description.
• the composition comprises at least one copolyamide obtained by polymerization of at least one constituent monomer of the polyamide and at least one or more comonomers.
• Advantageously said (s) copolyamide (s) are semi-crystalline.
• Said constituent monomer may be a monomer as defined in the preceding paragraphs. In particular, it is caprolactam or the corresponding amino acid.
• the copolyamide comprises a constituent monomer content of at least 80 mol% relative to the number of moles of the total mixture of monomers and comonomers of the copolyamide.
• comonomer also called minority comonomer, is understood to mean a compound different from the constituent monomer of the polyamide and capable of binding covalently to the constituent monomers of the polyamide, in particular via amide, ester or imide bonds, to form a copolyamide.
• the aromatic and / or cycloaliphatic comonomers preferably have at least one function selected from the group consisting of: an amino function Am, in particular capable of forming an amide bond with a carboxylic acid function of the constituent monomer of the polyamide;
• a carboxylic acid function Ac in particular capable of forming an amide bond with an amine function of the constituent monomer of the polyamide
• an OH alcohol function in particular capable of forming an ester bond with a carboxylic acid function of the constituent monomer of the polyamide
• dicarboxylic acid DA function in particular capable of forming an imide bond with an amine function of the constituent monomer of the polyamide.
• This dicarboxylic acid function may include the functions of geminal carboxylic acids or on vicinal carbon atoms.
• Amine function Am is preferably a primary amine function or its salt.
• the carboxylic acid function can be in salt form or not.
• the comonomer is represented by the following formula (I):
• R is a linear, branched, aliphatic, aromatic or cycloaliphatic hydrocarbon radical optionally comprising from 1 to 20 carbon atoms and optionally comprising heteroatoms such as N, O or P;
• x is between 0 and 4;
• - is between 0 and 4.
• z is between 0 and 4.
• comonomers may be chosen from the group consisting of:
• amino acids or aminocarboxylic acids for example comprising from 3 to 18 carbon atoms
• lactams for example, comprising from 3 to 18 carbon atoms
• diamines which may be aliphatic or aromatic or cycloaliphatic and preferably comprising from 3 to 18 carbon atoms;
• diacids which may be aliphatic or aromatic or cycloaliphatic, preferably comprising from 3 to 18 carbon atoms;
• the monoacid or monoamine compounds generally used as chain-limiting agents of the polyamide
• hydroxy acids or derivatives for example preferably comprising from 3 to 18 carbon atoms;
• the diols may be aliphatic or cycloaliphatic and preferably comprising from 3 to 18 carbon atoms;
• monomers comprising two carboxylic acid functional groups making it possible to form imide, aliphatic or aromatic or cycloaliphatic functional groups and comprising from 3 to 18 carbon atoms;
• aliphatic comonomers of those selected from the group consisting of: amino-1-undecanoic acid, amino-12-dodecanoic acid, lauryllactam, sebacic acid, dodecanedioic acid , tetramethylenediamine, trimethylhexamethylenediamine, adipic acid, hexamethylenediamine, oxalic acid, fumaric acid, maleic acid, methylglutaric acid, ethylsuccinic acid, metaxylylenediamine, paraxylylene diamine, methyl-1-pentamethylene diamine, fatty acids such as lauric acid, stearic acid, palmitic acid, benzyl acid, 1-naphthyl acetic acid, 3- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid, benzylamine, laurylamine, 1-naphthalenemethylamine
• Copolyamide within the meaning of the invention thus comprises at least one comonomer, at least one of which is an aromatic or cycloaliphatic comonomer.
• the copolyamide may comprise a mixture of an aromatic comonomer and a cycloaliphatic comonomer.
• aromatic comonomer is meant a comonomer comprising at least one aromatic ring and optionally one or more hydrocarbon chains, linear or branched.
• the copolyamide according to the invention may comprise at least less a minority aromatic comonomer, such as for example those selected from the group consisting of: terephthalic acid, isophthalic acid, benzoic acid, phenylenediamine, 1-naphthoic acid, anthracene-9- carboxylic acid, aniline, naphthylamine, 1,8-naphthalene dicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 5-hydroxyisophthalic acid, 5-sulfo isophthalic acid, 2,3-diaminonaphthalene , 1,5-diaminonaphthalene, 4-amino benzoic acid, 4-hydroxybenzoic acid, 1-hydroxy-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4,4'
• cycloaliphatic comonomer means a comonomer comprising at least one aliphatic ring and optionally one or more hydrocarbon chains, linear or branched.
• the copolyamide according to the invention may comprise at least one cycloaliphatic minor comonomer, such as, for example, those selected from the group consisting of: isophorone diamine, bis (3,5-dialkyl-4-aminocyclohexyl) methane, bis ( 3,5-dialkyl-4-aminocyclohexyl) ethane, bis (3,5-dialkyl-4-aminocyclohexyl) propane, bis (3,5-dialkyl-4-aminocyclohexyl) butane, bis ( 3-methyl-4-aminocyclohexyl) methane, p-bis (aminocyclohexyl) methane and isopropylidenedi (cyclohexylamine), 1,4-dicarboxycycl
• the copolyamide may also be a polymer comprising such star macromolecular chains, such as those described in documents FR2743077, FR2779730, US5959069, EP632703, EP682057 and EP832149. These compounds are known to have improved fluidity compared to linear polyamides of the same molecular weight. Particularly preferred copolyamides comprising as minor comonomers a mixture of cycloaliphatic diamine and aromatic diacid.
• a type 6 copolyamide comprising 4.7 mol% of a mixture of terephthalic acid and a diamine, in particular isophoronediamine;
• a type 6 copolyamide comprising 0.37 mol% of a mixture of isophthalic acid and a diamine, in particular isophoronediamine;
• a type 6 copolyamide comprising 2 mol% of a mixture of terephthalic acid and hexamethylene diamine
• a type 6 copolyamide comprising 13 mol% of a mixture of isophthalic acid and hexamethylenediamine
• a type 6 copolyamide comprising 2 mol% of a mixture of sebacic acid and isophorone diamine.
• the copolyamides can be manufactured in conventional ways by polymerization, especially continuous or discontinuous.
• the composition is in powder form.
• powder is meant an assembly of polyamide particles obtained according to various possible methods.
• the powder according to the invention can be obtained in various ways known to those skilled in the art depending on the materials used, such as by grinding, cryomilling, by polymerization, or by precipitation.
• documents EP1797141 and WO2007 / 1 15977 and WO2010 / 063691 can be cited.
• Said powder may in particular be manufactured by: a) melt blending a (co) polyamide with a compound A consisting of a polymeric material comprising at least a part of its structure compatible with said copolyamide and at least part of its non-compatible structure and insoluble in said copolyamide, for obtain a dispersion of discrete particles of copolyamide;
• the formation of the mixture is especially obtained by melting the (co) polyamide and adding the compound A in solid or molten form and applying a mixing energy to obtain the formation of the discrete particles of copolyamide dispersed in an advantageously continuous phase formed by the compound A.
• This mixture can also be obtained by solid state mixing of particles of said (co) polyamide and particles of said additive A, and melting of the mixture of particles with application to the molten mixture of a mixing energy to obtain the formation of discrete particles of (co) polyamides dispersed in an advantageously continuous phase formed by compound A.
• the mixture may comprise a weight content of (co) polyamide of between 50 and 90%, in particular between 70 and 80%.
• the concentration by weight of additive A in the mixture may be between 10% and 50%, advantageously between 20% and 30%. We recall that the terminals are included in the ranges presented.
• said powder consists of (co) polyamide and additive A, and optionally:
• the mixture can be obtained by any suitable device such as screw mixers or agitators compatible with the temperature and pressure conditions used for the implementation of the copolyamides.
• the molten mixture is shaped before the cooling step, for example in the form of filaments or rods. This shaping can be advantageously carried out by an extrusion process through a die. According to a preferred embodiment of the invention, especially when the molten mixture is shaped, this molten mixture is preferably produced in an extruder feeding the extrusion die.
• Cooling of the molten mixture can be achieved by any suitable means. Of these, air cooling or dipping in a liquid is preferred.
• the step of recovering the (co) polyamide powder advantageously consists in a disintegration treatment of the discrete (co) polyamide particles.
• This disintegration can be obtained by applying a shearing force on the cooled mixture.
• the disintegration of the (co) polyamide particles can also be obtained by quenching the cooled melt mixture in a liquid, non-solvent of the thermoplastic polymer and advantageously solvent of the additive A.
• the additive A is advantageously a polymer of the block, sequenced, comb, hyperbranched or star type.
• the structure compatible with the polyamide forms a block, a sequence, the skeleton or the teeth of the comb, the heart or branches of the polymer star or hyperbranché.
• the compatible structure of additive A comprises functions that are chemically identical to those of copolyamide.
• Compounds selected from the group comprising: block copolymers of ethylene oxide and propylene oxide (Pluronic® and Synperonic®) and polyalkylenes (Jeffamine®) are preferably used as additive A.
• the composition, in addition to (co) polyamide and additive A may comprise other compounds.
• Additive A may be used in combination with a compound B which is insoluble and not compatible with (co) polyamide.
• compound B has a chemical structure that is compatible with at least part of the structure of compound A, in particular the part of structure that is incompatible with (co) polyamide.
• compounds B which are suitable for the invention mention may be made of compounds belonging to the families of polysaccharides, polyoxyalkylene glycols and polyolefins.
• Compound B may be added separately from Compound A or as a mixture with at least a portion of Compound A. It may also be premixed with the thermoplastic polymer. This method makes it possible to obtain particles with a controlled geometry, in particular by adjusting the stirring during step a), the nature of compounds A and / or B, the temperature and the concentration of the various components of the mixture.
• a particle size distribution d50 between 20 and 100 ⁇ , preferably between 30 and 70 ⁇ , and also corresponding to the following relationship: (d90-d10) / d50 between 0.85-1, 3, preferably 0.9 -1, 2;
• sphericity factor of between 0.8 and 1, preferably between 0.85 and 1;
• an intra-particle porosity of less than 0.05 ml / g, preferably less than 0.02 ml / g, in particular for pore sizes greater than or equal to 0.01 ⁇ .
• the particle size distribution of the d50 particles, the sphericity factor, and the intraparticle porosity are in particular defined in the patent application WO2010 / 063691.
• compositions used according to the invention, the powder and / or the articles obtained may contain one or more additives or compounds chosen from the group comprising mattifying agents, thermal stabilizers, light stabilizers, pigments, dyes, reinforcement, such as glass fibers or mineral fibers, glass beads and carbon fibers, nucleants, and shock reinforcing agents such as elastomers, various metals and anti-caking agents such as silica .
• the present invention also relates to a method of manufacturing a shaped article by selective melting of layers, in particular by rapid prototyping using a laser, using a powder that can be obtained or obtained by the process according to the invention.
• the invention also relates to a shaped article by selective melting of layers as defined above.
• the selective melting of layers is a method of making articles consisting of depositing layers of powdery materials, selectively melting a portion or a region of a layer, and depositing a new layer of powder and melt again some of this layer and so on so as to obtain the desired object.
• the selectivity of the part of the layer to be melted is obtained for example by the use of absorbers, inhibitors, masks, or through the supply of focused energy, such as electromagnetic radiation such as a laser beam.
• Rapid prototyping is a process that allows to obtain parts of complex shapes without tools and without machining, from a three-dimensional image of the article to be produced, by sintering superimposed layers of powders using a laser.
• Generalities on rapid prototyping by laser sintering are mentioned in US6136948 and WO96 / 06881, US20040138363.
• the machines for carrying out these processes are composed of a construction chamber on a manufacturing piston, surrounded on the left and on the right by two pistons supplying the powder, a laser, and a means for spreading the powder, such as a roller.
• the chamber is generally kept at a constant temperature to prevent deformation.
• the powder is first spread in a uniform layer over the entire chamber, the laser then traces the 2D section on the surface of the powder, thus sintering. Caches can also be used.
• the manufacturing piston goes down the thickness of a stratum while one of the powder supply pistons rises. A new layer of powder is spread over the entire surface and the process is repeated until the piece is finished. The workpiece must then be removed carefully from the machine and cleaned of the unsintered powder surrounding it. There are other machines where the powder does not come from below thanks to pistons, but from the top. This method saves time because it is not necessary to stop the manufacture of parts to replenish the powder machine.
• Homopolyamide K122 sold by DSM, with a relative viscosity of 124 cm 3 / g according to the standards ISO 307, 1 157 and 1628.
• This homopolyamide 6 has a cold crystallization enthalpy according to the process P of 98 J / g.
• the powder obtained has a D50 distribution of 44.8 ⁇ and a particle size dispersion ((D90-D10) / D50) of 1.25.
• Type 6 copolyamide comprising 4.7 mol% of a mixture of 50% by weight of terephthalic acid and 50% by weight of isophorone diamine; relative viscosity 130 mg / L in formic acid.
• This polyamide has a cold crystallization enthalpy according to method P of 58 J / g.
• the powder obtained has a D50 distribution of 48.5 ⁇ and a granulometric dispersion ((D90-D10) / D50) of 1.2. These powders were homogeneously mixed with 0.2% by weight of precipitated silica before passing through the rapid prototyping machine. A thermal stabilizer is added to the washed rushes during the manufacturing process.
• powder A is a mixture of homopolyamide powder K122 with 0.2% by weight of precipitated silica
• powder B is a mixture of type 6 copolyamide powder as described above with 0.2% by weight of precipitated silica.
• the powders are sintered on a laser prototyping type machine marketed by 3DSystems.
• the particles are placed in two bins adjacent to the working surface and heated to a temperature of 150 ° C.
• the particles are brought to the work surface with a 100-150 micron roll.
• the work surface is heated to a temperature between 195 and 210 ° C.
• a laser of a powerful between 39 and 46W brings the complementary energy necessary for the sintering of the particles.
• the work surface is lowered and the roll then deposits a second layer of powder on the work surface and so on until the final article is obtained.
• Example 1 Powder A
• K122 homopolyamide powder 5 kg is introduced and then it is fixed on a rotary evaporator.
• a net of nitrogen is introduced, then the flask is heated to 200 ° C. by an oil bath. The temperature is maintained at 200 ° C for 30 minutes, then the oil bath is allowed to warm to 30 ° C. Finally, the powder is recovered.
• the temperatures Tir and Tfr are measured by the modulated DSC method P.
• Tfr-Tir The decrease in Tfr-Tir is therefore 42%.
• sintering tests with the treated powder A and with the untreated powder A show, in particular, an improvement in the heat flowability with the powder A having undergone the heat treatment.
• Example 2 Powder B The heat treatment protocol is identical to that described in Example 1, except that powder B (5 kg) is used. Table 2
• Tfr-Tir The decrease in Tfr-Tir is therefore 41%. Furthermore, as in Example 1, sintering tests with the treated powder B and with the untreated powder B also show an improvement in the hot flowability with the powder. B having undergone heat treatment.
• Examples 1 and 2 therefore demonstrate that the heat treatment makes it possible to reduce the difference between Tfr and Tir, but also to improve the behavior of the powders, especially in terms of heat flowability.

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