Classifications

• • 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
  • C08L77/06—Polyamides derived from polyamines and polycarboxylic acids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B9/00—Making granules
  • B29B9/02—Making granules by dividing preformed material
  • B29B9/06—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B9/00—Making granules
  • B29B9/02—Making granules by dividing preformed material
  • B29B9/06—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion
  • B29B9/065—Making granules by dividing preformed material in the form of filamentary material, e.g. combined with extrusion under-water, e.g. underwater pelletizers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B9/00—Making granules
  • B29B9/12—Making granules characterised by structure or composition
  • B29B9/14—Making granules characterised by structure or composition fibre-reinforced
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
  • B29B9/00—Making granules
  • B29B9/16—Auxiliary treatment of granules
• • 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
  • B29C45/00—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor
  • B29C45/0001—Injection moulding, i.e. forcing the required volume of moulding material through a nozzle into a closed mould; Apparatus therefor characterised by the choice of material
• • 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
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
• • 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
  • C08G69/48—Polymers modified by chemical after-treatment
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L75/00—Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
  • C08L75/04—Polyurethanes
  • C08L75/06—Polyurethanes from polyesters
• • 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

Definitions

• the invention relates to the use of a specific compound as a fluidizing agent or melt-blowing agent precursor of a composition comprising a thermoplastic polymer, in particular polyamide. It also relates to a process for preparing a polyamide-based article in which the melt viscosity of the composition comprising polyamide is decreased, and wherein the conditions, in particular temperature, duration and pressure, are such that they allow the generation of CO2, the latter being solubilized in said composition.
• the fluidizing agent or the precursor of the fluidizing agent may also make it possible to obtain an article having an undiminished density and / or an increase in the average molecular weight of the polymers of the composition.
• thermoplastic polymer article shaping processes such as extrusion and injection, particularly injection molding
• the decrease in the melt viscosity may facilitate certain processes for preparing articles comprising a thermoplastic polymer, and / or allow to obtain articles having more complex shapes.
• the polyamide-based compositions have a good compromise of the following three properties: melt flowability, good mechanical properties and surface appearance .
• the compositions are sufficiently fluid when they are melted, so that they can be conveyed and handled easily and quickly in certain shaping devices, such as, for example, injection molding.
• certain shaping devices such as, for example, injection molding.
• the fluidity of the formulations can make it possible not to be limited by the torque of the extruder, interest in particular to be able to increase the rate of charges and / or to limit the self-heating and thus to better control the temperature during the method of implementation. This can prevent degradation of the polymer matrix or heat-sensitive additives.
• these particularly interesting mechanical properties mention may be made of impact resistance, flexural or tensile modulus, bending stress or tensile stress.
• the prior art frequently mentions the use of reinforcing fillers, especially glass fibers to improve the mechanical properties.
• thermoplastic compositions having a high fluidity.
• thermoplastic composition based on polyamide having a good level of these different properties.
• US4369285 relates to reinforced thermoplastic moldings comprising polyamides and polyurethane, but it does not envisage conditions such that the polyurethane generates CO 2 , in addition it is silent on the fluidity aspect.
• DE4136078 relates to coupling reactions between polyamides and polyurethanes, in particular whose ends have isocyanate functions. In any case, it does not consider conditions in which the urethane functions generate CO 2 .
• WO95 / 13307 and WO90 / 1 1329 relate to processes involving relatively low processing temperatures. Thus, they do not envision conditions in which the urethane functions generate CO2.
• the object of the invention is to solve all or part of the problems mentioned above. It is particularly intended to provide a fluidifying agent or a precursor thereof and a method using this fluidizing agent having at least one of the following advantages: not to reduce the average molecular weight of the polyamide or thermoplastic polymer present in the article obtained , not to affect the average molecular weight of the polyamide, lead to compositions having improved characteristics, and in particular a compromise melt viscosity / mechanical characteristics / satisfactory surface appearance, in particular with a method easy to implement, do not not requiring very sharp and / or expensive equipment.
• the subject of the invention is a process for preparing a polyamide article comprising the steps of:
• Tf is meant in the sense of the present invention the melting temperature of the polyamide PA.
• the CO2 generated in this process essentially comes from, especially at least 85%, in particular at least 90%, or even at least 95%, or in part of reactions involving, directly or indirectly, the compound U, in particular it comes entirely from reactions
• the CO2 comes mainly or partly from the urethane functions.
• the compound U is in particular involved in the following reactions (in which R 3 NH 2 and R COOH respectively represent the amino and carboxylic end groups of the polyamide):
• the method according to the invention can therefore not reduce the molecular weight of polymers, a conventional method to reduce the viscosity.
• the process according to the invention can even allow an increase in the average molecular weight of the polymers of the composition.
• the process according to the invention can allow the fluidized composition to comprise no or few residues of fluidifying agents, the CO2 being removable and the residues of compounds U that can be bonded to PAs.
• CO2 has the advantage of being non-toxic, non-flammable and friendly to the environment.
• the process allows a decrease in the melt viscosity by at least 10%, especially by at least 20%, in particular by at least 25%, with respect to a composition in which the compound U is replaced by the PA and / or in which the PU does not generate CO2 in an effective amount, or no CO 2 at all.
• the process may allow a 30%, in particular 50% or even 55% decrease in melt viscosity.
• the melt viscosity of the composition is measured at 896s -1 with a capillary die having a length / diameter ratio of 30/1, more particularly, this viscosity is measured according to the protocol described in the examples.
• the temperature T is greater than the melting temperature of the PA -30 ° C, ie Tf-30 ° C. In particular, this temperature T is greater than or equal to Tf-10 ° C. and more particularly T is greater than or equal to the Tf of PA.
• the temperature may be greater than or equal to 280 ° C., in particular greater than or equal to 290 ° C., even greater than or equal to 300 ° C., or even greater than or equal to 305 ° C.
• the temperature T to be reached during step a) of the process of the invention, in particular combined with the time t, must also allow the formation of carbon dioxide, in particular an effective amount of CO2.
• an effective amount is meant a quantity of CO2 generated allowing a decrease in the melt viscosity of at least 10%, in particular by at least 20%, in particular by at least 25% relative to a composition in which the compound U is replaced by the PA and / or in which the PU does not generate CO 2 .
• the amount of CO2 released by the compound U may be greater than or equal to 0.1% by weight, in particular greater than or equal to 0.2% by weight, or even greater than or equal to 0.3% by weight relative to the total weight. of the composition.
• the CO2 release test by the compound U in the process and the amount generated can be estimated by putting the composition under the process conditions, or under similar conditions in terms of temperature, duration and shear conditions, and then bringing the melted composition at atmospheric pressure to measure the amount of CO2 released.
• step a) may vary. However, it is adapted according to different parameters, such as the temperature T and the desired properties. This duration can however go from 20 seconds to 30 minutes, in particular from 30 seconds to 15 minutes, or even from 1 to 6 minutes.
• the temperature and time are such that they allow a decrease in the melt viscosity of the composition. In particular, they are also such that they allow an increase in the average molar mass of the polymers of the composition.
• a catalyst can be used to accelerate the decarboxylation reaction of carbamic anhydride and acid obtained by reacting the acid function with the isocyanate function; by way of example, mention may be made of tertiary amines such as diazabicyclooctane (DABCO), diazabicycloundecene (DBU) and triethylamine.
• DABCO diazabicyclooctane
• DBU diazabicycloundecene
• triethylamine triethylamine
• the pressure P of the process is in particular such as to keep the generated CO2 solubilized in the mixture of PA and compound U, this pressure may in particular be greater than or equal to 10 bar, in particular greater than or equal to 20 bar, all particularly greater than or equal to 30 bars, or even greater than or equal to 40 bars.
• the polyamide PA of the invention is a polyamide of the type obtained by polycondensation from dicarboxylic acids and diamines, or of the type obtained by polycondensation of lactams and / or amino acids.
• the polyamide of the invention may be a mixture of polyamides of different types and / or of the same type, and / or copolymers obtained from different monomers corresponding to the same type and / or to different types of polyamide.
• the polyamide PA of the invention advantageously has a molecular mass greater than or equal to 10,000 g / mol, preferably greater than or equal to 14,000 g / mol, and even more preferably greater than or equal to 16,000 g / mol.
• polyamide 6 polyamide 7, polyamide 6,6, polyamide 11, polyamide 12, polyamide 13, polyamides 4,6; 6.10; 6.12; 10.10; 10.6; 12.12; 6.36; semi-aromatic polyamides, especially in which the diamine part is aromatic in whole or in part, and in particular is of the meta-xylylenediamine type, for example MXD6, polyphthalamides obtained from terephthalic, isophthalic and / or naphthalic acid , such as 9T, 10T, 11T, 12T, 13T, 6T / MT, 6T / 6I, 6T / 66, 66 / 6T, 61, 6I / 6T, 10N, 11N, 12N, such as the polyamides marketed under the trade name AMODEL, copolyamide 6/6/6, 6/1 1, 6/12 and 1 1/12, their copolymers and alloys.
• AMODEL polyamide 6/6/6, 6/1 1, 6/12 and 1 1/12
• the polyamide is chosen from polyamide 6, polyamide 6,6, their mixtures and copolymers.
• the polyamide is polyamide 6,6.
• the polyamide PA of the invention is a linear polyamide.
• the polyamide PA of the invention comprises star or H macromolecular chains, and, if appropriate, linear macromolecular chains.
• the polymers comprising such star or H macromolecular chains are for example described in the documents FR2743077, FR2779730, US5959069, EP0632703, EP0682057 and EP0832149.
• the polyamide PA of the invention is a copolyamide having a random tree structure. These copolyamides of random tree structure and their method of production are described in particular in document WO99 / 03909.
• the polyamide PA of the invention may be a low viscosity polyamide, as described in WO2008 / 107314.
• the polyamide PA of the invention may also be a composition comprising a linear polyamide and as additive a star polyamide, H and / or tree as described above.
• the polyamide PA of the invention may also be a composition comprising as additive a hyperbranched copolyamide of the type of those described in WO 00/68298.
• the polyamide PA may optionally comprise other functions such as ester, urea and / or ether functions, etc.
• the polyamide PA may be present in the composition in a content ranging from 30 to 99.9% by weight, especially from 35 to 99% by weight, or even from 40 to 98% by weight relative to the total weight of the composition.
• the compound U comprises at least one urethane function. It can be a polyurethane, also called PU, or a polyisocyanate type compound blocked by an alcohol or a phenol. According to a particular embodiment, the compound U is a thermoplastic polyurethane. In particular, compound U, and even more particularly when it is a polyurethane, is immiscible with PA66.
• the compound U is said to be "immiscible" if, in a surface area of 500 ⁇ 2 in the center of said granule, there are at least 10 nodules, the largest dimension of which is at least 50 nm, the count being, of course, the average counts on the five sections.
• the compound U is a polyurethane
• it can be obtained from a diisocyanate, a polyol and optionally a short chain diol.
• the compound U does not include free isocyanate functions, especially at the end of chains, and / or it is not a polyurethane comprising at least a polycarbonate part even more particularly, the terminal functions of said polyurethane are hydroxyl functions.
• diisocyanates which can be used for the preparation of the polyurethane are isophorone diisocyanate, 1,3-and 1,4-cyclohexane diisocyanate, 1,2-ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1, 6-hexamethylene diisocyanate, 2,2,4 and 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, alpha, alpha'-diisocyanatodipropyl ether, 1,3-cyclobutane diisocyanate, 2,2- and 2,6-diisocyanato-1-methylcyclohexane, 2,5 and 3,5-bis (isocyanatomethyl) -8-methyl-1,4-methano-decahydronaphthalene, 1,5-diisocyanate, 2,5-, 1, 6- and 2,6-bis (isocyanatomethyl) -4,7-methanohex
• the polyol used for the preparation of the polyurethane may be a polyester, a polycaprolactone or a polyether.
• the polyesters are derived from the condensation of a dicarboxylic acid, usually adipic acid, with a diol.
• polyester mention may be made of poly (butanediol adipate), poly (hexanediol adipate), poly (ethanediol-butanediol adipate), etc.
• Polycaprolactones are polyesters derived from the polymerization of [epsilon] caprolactone and diols.
• a polyether mention may be made of poly (ethylene glycol) (PEG), poly (propylene glycol) (PPG), poly (tetra methylene glycol) (PTMG) and the like.
• the short chain diol that can be used for the preparation of the polyurethane can be hexanediol or butanediol, or an aromatic diol.
• the polyurethane is advantageously a thermoplastic polyurethane.
• the polyurethane may be aromatic or aliphatic, for example depending on the aromatic or aliphatic nature of the diisocyanate used to prepare it.
• the polyurethane of the invention is aliphatic.
• the polyurethane of the invention may be a mixture of several different polyurethanes.
• the polyurethane has a molecular mass greater than or equal to 2000 g / mol.
• it has a molecular mass greater than or equal to 5000 g / mol, preferably greater than or equal to 10000 g / mol, and even more preferably greater than or equal to 13000 g / mol.
• the compound U may be present in the composition in a content ranging from 0.1 to 15% by weight, in particular from 0.5 to 12%, in particular from 1 to 10% by weight and very particularly from 2 to 5% by weight. weight, or even 2 to 4% by weight relative to the total weight of PA and compound U.
• the weight ratio PA / compound U is from 1000 to 2, in particular from 100 to 4, most preferably from 100 to 9, or even from 50 to 15.
• the composition comprises a number of moles of urethane function greater than or equal to the number of terminal amino functions of the AP.
• the composition comprises a number of moles of urethane function greater than or equal to the sum of the number of moles of amine functions of AP and the number of moles of terminal carboxylic acid functions of PA.
• composition may comprise a number of moles of urethane function that is less than or equal to the sum of the number of moles of terminal amine functions of the AP, the number of moles of terminal carboxylic acid functions of the PA, and twice the number of moles of water.
• the composition may also comprise a high proportion of additives and may for example be used as a masterbatch intended to be mixed with another thermoplastic composition, in particular based on polyamide.
• composition may comprise porogenic agents, surfactants, nucleants such as talc, and / or plasticizers.
• composition may also comprise compounds such as mattifying agents, such as titanium dioxide or zinc sulphide, pigments, dyes, heat or light stabilizers, bioactive agents, anti-fouling agents, antistatic agents, flame retardants, etc.
• mattifying agents such as titanium dioxide or zinc sulphide, pigments, dyes, heat or light stabilizers, bioactive agents, anti-fouling agents, antistatic agents, flame retardants, etc.
• the composition comprises at least one reinforcing filler and / or a filler.
• This filler may be selected from fibrous fillers, such as glass fibers, carbon fibers, natural fibers, and / or non-fibrous fillers.
• Natural fibers can be hemp and / or flax.
• non-fibrous fillers mention may be made of particulate, lamellar and / or exfoliable or non-exfoliatable nanofillers, such as alumina, carbon black, clays, zirconium phosphate, kaolin, calcium carbonate, copper, diatoms, graphite, mica, silica, titanium dioxide, zeolites, talc, wollastonite, polymeric fillers, such as dimethacrylate particles, glass beads or glass powder.
• particulate, lamellar and / or exfoliable or non-exfoliatable nanofillers such as alumina, carbon black, clays, zirconium phosphate, kaolin, calcium carbonate, copper, diatoms, graphite, mica, silica, titanium dioxide, zeolites, talc, wollastonite
• polymeric fillers such as dimethacrylate particles, glass beads or glass powder.
• the composition may comprise several types of reinforcing fillers.
• the glass fibers may be of the so-called chopped type, in particular having a diameter of between 7 and 14 ⁇ . These fillers may have an average length of between 0.1 and 5 mm. These fillers may have a surface size which ensures the mechanical adhesion between the fibers and the matrix polyamide, especially in critical environmental conditions, such as, for example, in contact with the engine fluids.
• composition comprises from 20 to 70% by weight, in particular from 30 to 60% by weight of reinforcing filler relative to the total weight of the composition.
• the composition can be prepared by intimately mixing the various compounds, especially in the form of powders or by introducing the urethane compound into the polyamide in the molten state.
• the mixture may for example be made in an extrusion device.
• the polyamide may also be in the form of granules, which is coated with urethane compound.
• the composition When the composition is prepared using an extrusion device, it can then be shaped into granules. These granules can then be used as such to carry out the process according to the invention.
• the granulation of the composition can be carried out by any type of granulation technology, in particular the conventional granulation by calling the extruded rod (s) of the die and cooling in a water bath or granulation. by drowned head cut.
• the composition is prepared by introducing the urethane compound into the molten polyamide, the temperature of the medium being chosen so as to avoid any significant evolution of gas.
• the preparation temperature of the composition of the invention is greater than or equal to Tf-30 ° C, preferably greater than or equal to Tf-20 ° C, even more preferably greater than or equal to Tf-10 ° C, Tf being the temperature melting point (in ° C) of the polyamide PA of the composition.
• the preparation temperature of the composition is in particular less than or equal to 275 ° C., or even 270 ° C., and more particularly to 265 ° C., in particular in the case where the compound U is an aliphatic polyurethane.
• the composition may be prepared in an extruder and then granulated.
• the granules obtained can then be introduced directly into a transformation and shaping device.
• the composition is in the form of granules.
• the granulation of the composition may be carried out by drowned head cutting. It is not the one used here but it could be interesting at least for the preparation step of PA / compound U granules.
• the temperature T and the duration t are also such that they also allow the average molar mass of the thermoplastic polymer to be at least equal to the molar mass of the starting polyamide.
• the average molecular weight may be by weight or number.
• the number-average molar mass can be increased by at least 5%, especially by at least 7%, or even by at least 10%.
• the weight average molar mass may be increased by at least 5%, especially by at least 7%, especially by at least 10%, or even at least 15%.
• Step a) may be carried out at a temperature greater than or equal to the AP Tf and sufficient for there to be a gas evolution, in particular of CO2. Furthermore, step a) can be carried out at a temperature less than or equal to the highest of the temperatures chosen between Tf + 40 ° C and 310 ° C.
• the residence time t of the composition at a temperature T can range from 20 seconds to 15 minutes, in particular from 30 seconds to 10 minutes, or even from 1 to 5 minutes.
• PA6, 66, MXD6 and their copolymers especially in the case of PA6, 66, MXD6 and their copolymers, and most particularly in the case of PA6, 66 and copolymers.
• the method results in an article having a density d greater than 0.95 times that of its components (weighted by their content in the composition leading to the article).
• the density d of the article consisting of compounds C1 to Cx in contents X1 to Xn, in% by weight relative to the total weight of the composition, which can be defined by the following relationships (1) and (2): d> A x D
• C1, C2, Cn represent the compounds 1, 2, n present in the composition used to obtain the article
• a x B means A multiplied by B.
• An article corresponding to this relation can in particular be obtained a process involving injection molding in which a quantity of composition is introduced into the mold allowing the filling of the mold without expansion of gas, in particular of the CO2 generated.
• the density may be greater than or equal to 1, in particular greater than or equal to 1, 10 and in particular in the case of a glass fiber-filled composition, the density may be greater than or equal to 1, 2.
• the density of the article in particular in a content ranging from 30 to 60% by weight as a contribution to the total weight of the composition, the density of the article may range from 1.3 to 1, 8.
• the method according to the invention comprises a shaping step a ') implementing a molding device, in particular an injection molding device, and an extrusion device.
• this method comprises an injection molding step
• the amount of composition injected is such that it makes it possible not to form voids and / or micro-voids leading to a decrease in the density, in particular the molding by injection does not lead to a lighter foam.
• the subject of the invention is an article comprising a polyamide and a polymer derived from polyamide, in particular in which
• the average molar mass in number and / or weight of the polymers present in this article is greater than that of the starting polyamide, and / or
• melt-blowing agent precursor of a composition comprising at least one thermoplastic polymer, in particular polyamide, or
• the fluidizing agent or the precursor of fluidizing agent may also allow, together with an improvement in the melt flow:
• thermoplastic polymer to not reduce, or even increase, the average molar mass of the thermoplastic polymer, and / or
• the contents of the carboxylic acid and amine end groups of the polyamides are determined by potentiometry.
• GTA stands for amine end groups and GTC stands for carboxylic acid end groups.
• the number and weight average molar masses of the polyamides were determined by gel permeation chromatography in polystyrene equivalent in dichloromethane after derivatization and detection by UV absorbance.
• the Viscosity Indices (IV) of the polyamides are measured from a 0.5% solution of polymer dissolved in 90% formic acid, according to ISO EN 307.
• the rheological properties of the polyamide granules containing or not the fluidizing agent were studied by means of an in-line rheometer, At Line Rheomether (ALR) from Gottfert (ALR-M 71 .02 model 019.03.05).
• ALR is a rheometer composed of a capillary die fed from a single-screw extruder via a gear pump. The single screw extruder has a diameter of 25 mm and a length / diameter ratio of 20.
• the mass flow rate of molten polymer and thus the shear rate are controlled by the speed of the gear pump.
• the melt viscosity is calculated from the difference between the measured pressures at the inlet and the outlet of the capillary. In the case of the ALR, the pressure at the outlet of the capillary is the atmospheric pressure.
• a counterpressure chamber also commercialized by Gottfert, has been added to the outlet of the capillary die of the ALR.
• This counterpressure chamber contains a conical needle which can move vertically by means of a thread. The vertical movements of the conical valve make it possible to modulate the level of constriction of the flow of molten polymer, and consequently the back pressure in the chamber as well as the average pressure of the viscosity measurement.
• the compounds used are the following:
• compositions Aliphatic thermoplastic polyurethane based on ⁇ -caprolactone (epsilon-caprolactone) sold under the name Krystalgran PN03-214 by the company Huntsman
• the compositions are prepared by melt blending, using a THERMO PRISM co-rotating twin-screw extruder model TSE16TC, having a diameter of 16 mm and a length / diameter ratio of 25.
• the compositions prepared are the following :
• Composition A1 90% by weight of polyamide and 10% by weight of polyurethane relative to the total weight of the composition
• Composition A2 95% by weight of polyamide and 5% by weight of polyurethane relative to the total weight of the composition
• Composition A3 98% by weight of polyamide and 2% by weight of polyurethane relative to the total weight of the composition
• composition A4 100% by weight of polyamide relative to the total weight of the composition
• the extrusion conditions for preparing the granules of compositions A1 to A4 are:
• the extruded A1-A4 compositions are cooled in water at room temperature and cut into granules.
• Example 2 Properties of the Polyamide Granules Containing the Thinning Agent at 310 ° C.
• the polyamide granules containing the fluidizing agent were placed in the hopper of the nitrogen-fed ALR single screw extruder.
• the capillary outlet pressure was maintained above 100 bar thanks to the backpressure cell in order to keep the solubilized CO2 in molten polyamide and to avoid the appearance of gas bubbles.
• Viscosity measurements were made at a shear rate of 896 sec- 1 with a capillary die having a length / diameter ratio of 30: 1.
• the conditions and the results of the viscosity measurements as well as the average molar masses of the polyamides leaving the capillary die are shown in Table 2.
• the average pressure of the viscosity measurement reported in Table 2 corresponds to the arithmetic mean between the pressures. measured at the inlet and the outlet of the capillary in the presence of the backpressure cell.
• Example 3 Properties of the polyamide granules containing the fluidizing agent at 280 ° C.
• the polyamide granules containing the fluidizing agent were placed in the hopper of the nitrogen-fed ALR single screw extruder.
• the capillary outlet pressure was maintained above 100 bar thanks to the backpressure cell in order to keep the solubilized CO2 in molten polyamide and to avoid the appearance of gas bubbles.
• Viscosity measurements were made at a shear rate of 896 sec- 1 with a capillary die having a length / diameter ratio of 30: 1.
• Example 4 Properties of polyamide granules containing the fluidizing agent at 300 ° C.
• the influence of the presence of the fluidizing agent in the polyamide granules was studied at 300 ° C., a temperature which also makes it possible to degrade the urethane functions of the fluidizing agent to isocyanate functions and consequently to generate CO 2 .
• the temperature profile used is described in Table 5.
• the polyamide granules containing the fluidizing agent were placed in the hopper of the nitrogen-fed ALR single screw extruder.
• the capillary outlet pressure was maintained above 100 bar thanks to the counter-flow cell. pressure in order to keep the CO2 solubilized in molten polyamide and to avoid the appearance of gas bubbles.
• Viscosity measurements were made at a shear rate of 896 sec- 1 with a capillary die having a length / diameter ratio of 30: 1.
• the conditions and the results of the viscosity measurements as well as the average molar masses of the polyamides at the outlet of the capillary die are collated in Table 6.
• the average pressure of the viscosity measurement reported in Table 6 corresponds to the arithmetic mean between the pressures. measured at the inlet and the outlet of the capillary in the presence of the backpressure cell.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Mechanical Engineering (AREA)
• Engineering & Computer Science (AREA)
• General Chemical & Material Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Compositions Of Macromolecular Compounds (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Polyamides (AREA)
• Other Resins Obtained By Reactions Not Involving Carbon-To-Carbon Unsaturated Bonds (AREA)
• Polyurethanes Or Polyureas (AREA)

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