Classifications

• • 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
  • C08J7/044—Forming conductive coatings; Forming coatings having anti-static properties
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J3/00—Processes of treating or compounding macromolecular substances
  • C08J3/20—Compounding polymers with additives, e.g. colouring
  • C08J3/205—Compounding polymers with additives, e.g. colouring in the presence of a continuous liquid phase
• • 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
  • C08J7/043—Improving the adhesiveness of the coatings per se, e.g. forming primers
• • 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
  • C08J7/046—Forming abrasion-resistant coatings; Forming surface-hardening coatings
• • 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
  • C08J7/048—Forming gas barrier coatings
• • 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
  • C08J7/052—Forming heat-sealable coatings
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/34—Silicon-containing compounds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K2201/00—Specific properties of additives
  • C08K2201/011—Nanostructured additives

Definitions

• the invention relates to the field of coating, that is to say the formation of a thin layer on a support, from a fluid dispersion, and with a view to giving said support specific properties.
• the invention relates more particularly to fluid dispersions, and the corresponding coatings, comprising a nanocomposite mineral filler.
• the invention also relates to the field of packaging, that of flexible, rigid or semi-rigid plastic packaging, and in particular the packaging of products sensitive to oxygen.
• Nanoparticulate clays are treated treated with intercalating agents in order to obtain compositions with spaced sheets, as described for example in US patents 5,952,095, 5,880,197, 5,877,248, 5,866,645, 5,578,672 and 5,552,469, as well as in international application WO99 / 32403.
• Nanocomposite materials with a typically polymeric matrix and with reinforcement based on nanoparticles formed by exfoliation of clay, clay treated or not treated with intercalation agents are already known.
• US patents 5,972,448, 5,876,812 and international applications O99 / 02593, WO98 / 29499 and WO98 / 01346 describe nanocomposites, or nanocomposite containers, based on PET, having improved barrier and heat resistance properties , the barrier properties increasing with the form factor of the nanoparticles.
• US patent 5,910,523 describes polyolefin-based nanocomposites in which the nanocomposites have been treated with a silane-based coupling agent.
• international application WO99 / 07790 describes nanocomposites based on a polymer matrix and on a block or graft copolymer.
• US Patent 5,844,032 describes nanocomposites based on VOH.
• US Patent 5,883,173 describes the manufacture of a nanocomposite latex emulsion comprising, in addition to a nanocomposite clay, a surfactant typically consisting of a quaternary ammonium salt, a polymer formed by polymerization of a monomer, said polymerization taking place after impregnating the clay with said monomer.
• patent GB 1 469 710 discloses hectorite in the form of a stable sol as a nanoparticulate filler.
• Document WO 00/40404 discloses coatings on films of nanoparticulate compositions based on EAA so as to obtain a barrier effect.
• Document EP 518 647 discloses coatings on films of compositions based on vermiculite and EVA so as to obtain a barrier effect.
• WO 00 49072 discloses plastic food or drink containers
• PET bottle coated with a coating based on dispersed montmorillonite and CYMEL ⁇ resin, so as to obtain a barrier effect or resistance to scratching.
• nanocomposites are already known to improve the performance of the polymer matrix in many fields, in particular to improve its mechanical characteristics, its gas barrier properties, or even its thermal stability, there is a constant need to increase the intrinsic performance of nanocomposites, or even possibly to reduce their cost at constant performance,
• the invention describes a process for manufacturing a nanocomposite dispersion, comprising a solvent, a resin dispersible or soluble in said solvent and a nanoparticulate mineral filler based on a phyllosilicate in the exfoliated state, nanocomposite dispersion intended to be applied to a support for forming, typically by coating and after removal of said solvent, a nanocomposite layer comprising said resin serving as film-forming matrix for said mineral filler in the exfoliated state.
• this method therefore comprises a step a) of forming an intermediate nanoparticulate dispersion, and a step b) of forming said nanocomposite dispersion proper which comprises said resin.
• a nanoparticulate mineral filler CM is selected, typically a commercial filler, suitable for the solvent S of said nanocomposite dispersion.
• the solvent S will most often itself be chosen as a function of the nature of said resin R, the latter varying according to the type of application and the properties desired for said nanocomposite layer and which have been demonstrated with the work of the plaintiff.
• Solvent S may be a mixture of solvents miscible with each other, insofar as the formulation of resins most often uses mixtures of solvents.
• the invention aims in particular to modify coatings or varnishes, typically standard varnishes, in order to obtain these same varnishes loaded with exfoliated nanoparticles.
• the invention can therefore relate to numerous applications, and potentially the entire field of traditional coating from standard fluid compositions, in particular in the field of packaging, given the diversity of technical effects brought about by the presence of 'an exfoliated nanoparticulate charge, some of these effects being already well known in the state of the art but to a lesser degree, others having been highlighted by the work of the applicant, as will appear in what follows.
• the invention is not limited only to the field of packaging insofar as it can be applied to the surface of any object capable of being coated, with a view to giving it one of the properties obtained with the coatings according to the present invention.
• the speed gradient VL / e is equal to 15080 s ' 1 .
• the S-CM pair is a possible pair for implementing the method of the invention.
• a first selection of S-CM couples is carried out by this relatively rapid method, a method which translates the possibility of swelling of the mineral charge in the solvent, which is a condition which is undoubtedly necessary - but not sufficient - to obtain the exfoliation of the sheets according to the invention.
• a second, more severe selection is then carried out, by completing the preceding examinations as indicated below, in order to evaluate the possibility of obtaining, within a reasonable time, a complete exfoliation of the mineral load, also leading to factor sheets.
• high L / Ec form The couple S-CM can be retained if the mineral load CM has exfoliated if not entirely, at least in the vast majority.
• transmission electron microscopy or TEM according to the acronym in English language commonly used is used to find out whether or to what extent a mineral filler is exfoliated.
• the X-ray spectra make it possible to follow the swelling of the mineral load until a spacing of its sheets of approximately 8 nm, but not until complete exfoliation, which implies an average spacing of at least 10 nm, more than 5 times the initial spacing between sheets, then possibly the disappearance of the order and the parallelism between sheets, the sheets can then be randomly oriented in the dispersion, at least if the form factor of the exfoliated sheets is not too high .
• FIGS. 3a to 3c show, schematically, respectively, sheets Mo of an initial mineral filler CM, sheets which move away while remaining ordered, and sheets M exfoliated.
• An S-CM pair will only be retained if it leads to a nanoparticulate dispersion typically analogous to that shown schematically in FIG. 3c, or again in FIGS. 7a and 7b.
• the limits of the experimental conditions of step a) of forming said nanoparticulate dispersion are also determined, following the work of the Applicant:
• the maximum shear rate Y X is first determined using the same device that used to select the S-CM pair, by evaluating, by TEM, the form factor L / Ec of the exfoliated sheets M and comparing it to the form factor Lo / Ec of the starting sheets M. For this, we apply, for 30 min, different shear speeds (by varying ⁇ up to 24,000 rpm) and we thus determine the maximum shear speed Y MA as being that above which the form factor L / Ec would drop too much, typically falling below 0.5.Lo / E c .
• a typical exfoliation means may comprise a moving part rotating inside a fixed part within said nanoparticulate dispersion, these parts being spaced by the distance "e" between fixed part and mobile part, which results in the passage of a nanoparticulate dispersion flux between these fixed and mobile parts, said flux being subjected to a shearing action characterized, as seen above, by a shearing speed ⁇ , or possibly by a speed gradient.
• the invention is not limited to the use of this type of device to rotor and stator.
• the overall level of shear to which said nanoparticulate dispersion will be subjected will depend on the shear rate ⁇ , on the duration of the average stay ⁇ of said dispersion in said exfoliation means, which is the residence time which is itself even proportional to the flux and shear time.
• the exfoliation speed varies with the shear speed ⁇ (or with the speed gradient), with the flux , and also with the viscosity ⁇ of the nanoparticulate dispersion.
• the viscosity of the nanoparticulate dispersions decreases when the shear rate increases.
• the duration T1 of step a) of exfoliation will therefore be able to vary considerably depending in particular on the shear speed ⁇ chosen.
• Turrax ® a typical Shear duration Tl is 15 min with a shear speed ⁇ of around 8000 s -1 .
• the duration T1 can range from a few hours with a shear speed of the order of 1000 s _1 to a few tens of hours with a shear speed of the order of 100 s _1 or less.
• a minimum shear speed Y IN could possibly be determined below which the exfoliation speed would be too low for a given industrial process.
• the duration T1 of step a) of exfoliation can also include a first phase without shearing, followed by a second with shearing.
• the viscosity of the nanoparticulate dispersion is included in a viscosity range ⁇ typically ranging from 0.05 Pa.s to approximately 10 Pa.s, in function of the S-CM couples selected according to the invention, viscosity values measured under a shear rate of 100 s " , and preferably in a viscosity range from 0.1 Pa.s to 1 Pa.s.
• ⁇ MX the maximum viscosity ⁇ MX was taken equal to that of the gel formed when the concentration Cl becomes equal to
• the method according to the invention makes it possible to transform a mineral filler into a nanoparticulate dispersion consisting of exfoliated sheets M, with an exfoliation speed sufficient to have an industrial process, and without reducing too much the form factor L / Ec of the exfoliated sheets M.
• step b) it relates to the manufacture of the nanocomposite dispersion D by incorporating the resin R into the nanoparticulate dispersion C obtained in step a).
• concentration C2 of resin R will depend on its nature, on the desired final properties and possibly on the viscosity or the rheological behavior of said nanocomposite dispersion taking into account the technique of coating the support P, but the C2 / C1 ratio will generally be understood. between 1 and 60, and most often between 5 and 20, Cl being the weight concentration of said mineral filler in said nanocomposite dispersion,
• this step b) can optionally take place above the glass transition temperature, conventionally called "Tg", of the resin R, in particular in the case where said resin is a dispersion in a solvent medium and not a solution.
• Tg glass transition temperature
• This temperature Tg is determined by known means, in particular from the tangent curve ⁇ as a function of the temperature, as illustrated in FIG. 6.
• the Applicant has observed that the Tg of the resin in the final dispersion could be different from that of the starting resin, and in particular be increased. According to a hypothesis put forward by the applicant, the exfoliated sheets could decrease the mobility of the macromolecular chains of said resin, and thus increase its Tg.
• step b) the incorporation of the resin is done with simple stirring which can correspond to relatively low shear rate ⁇ typically ranging from 100 to 400 s "1. It is important to note how different the shear conditions are in step a) and in step b), in particular so as not to decrease the factor the shape of the sheets exfoliated during this step.
• the duration T2 of this step b) is the time of dispersion of the resin R in the nanoparticulate dispersion C, time which is typically between 1 and 4 hours.
• step b) it is possible to employ, for a relatively short time of the order of a few minutes, additional dispersing means using for example an ultrasonic disperser, so as to o to obtain a nanocomposite dispersion D free of agglomerates, in particular of resin agglomerates, which would have a size greater than the thickness of the final coating E.
• additional dispersing means using for example an ultrasonic disperser, so as to o to obtain a nanocomposite dispersion D free of agglomerates, in particular of resin agglomerates, which would have a size greater than the thickness of the final coating E.
• the invention makes it possible to obtain nanocomposite coatings or layers on all types of supports which have remarkable properties both quantitatively by the level reached, in particular in the case of properties already known. , only qualitatively by the nature of these properties in the case of new properties.
• the invention makes it possible to considerably reduce the permeability of nanocomposite layers, in particular when said resin is EVOH.
• the final orientation of the sheets on the support may be related to the fact that the dispersion D is fluid when it is applied to the support P, and to the fact that it is applied by coating , typically with a roller, which can locally create a flow of the dispersion which can automatically orient the sheets parallel to the surface of the support P, also taking into account the fluidity of said nanocomposite dispersion D at the time of its application by coating.
• the Applicant has observed that the nanocomposite D dispersions comprising mineral fillers exfoliated in M sheets become considerably thinner under shear, as can be seen in FIG. 11, to the point that their viscosity tended to join, if not that of the solvent S alone, at least that of the resin R alone or of its dispersion or solution in said solvent.
• Figure 1 is a block diagram of the method according to the invention.
• FIG. 2 represents, in the ⁇ - ⁇ plane (shear - viscosity), the domains I and EdT of exfoliation of the mineral charge, the domains I and EdT corresponding respectively to the invention and to the state of the art.
• FIGS. 3a to 3b respectively illustrate, schematically, sheets of an initial mineral filler CM, sheets which move away while remaining ordered, and sheets exfoliated.
• the initial leaves Mo are of length Lo
• the exfoliated leaves M are of average length L ⁇ Lo in FIG. 3 c.
• FIG. 4 represents the model for calculating the permeability of a two-layer material in the form of a film F, comprising a support P and a layer or coating E formed by application of said nanocomposite dispersion D on this support P.
• This model allows, from the measured permeability P, the permeability of the support Pp, and the thicknesses EF, EE and Ep of the film F respectively, of the coating E and of the support P, to determine the permeability P E of the coating E.
• FIG. 5 represents the Nielsen tortuosity model making it possible to evaluate either the average form factor L / Ec or the volume fraction of the sheets exfoliated in the layers obtained from dispersions according to the invention, according to which we respectively know the volume fraction ⁇ M OR the average form factor L / Ec of the exfoliated sheets.
• ⁇ M the volume fraction of the sheets exfoliated in the layers obtained from dispersions according to the invention
• ⁇ M the average form factor
• Figure 6 is a tangent record ⁇ - equal to the ratio of the imaginary and real parts of the resin module - as a function of the temperature T ° C, making it possible to determine the glass transition temperature or Tg of the vinyl resin used for the tests, and of the same resin comprising 3% by weight of Cloisite 30B as mineral filler.
• Curve A corresponds to a vinyl resin whose Tg is 59 ° C
• curve B corresponds to a layer formed from a dispersion according to the invention comprising the same vinyl resin as matrix and 3% of Cloisite 10A as mineral filler, and whose Tg is 67 ° C.
• FIG. 7a is a micrograph (50 nm scale) typical of a layer formed from an aqueous dispersion according to the invention of EVOH resin and of 2% of Cloisite Na + ® as mineral filler, whereas FIG. 7b is the graphic transcription of this micrograph.
• FIG. 8a is a micrograph (scale of 50 nm) of a nanocomposite according to the prior art, formed by extrusion of PA6 with 5% Cloisite 30B® as mineral filler, while FIG. 8b is the graphic transcription of this micrograph.
• FIGS. 9a to 10b relate to means for measuring specific properties of the nanoparticulate layers obtained.
• Figures 9a and 9b illustrate a device (4) for measuring the temperature at which a film F consisting of a support P coated with a nanocomposite layer E seals on itself.
• FIG. 9a illustrates the position of the heating jaws (40) in the open position, the film F being folded in accordion with the nanocomposite layer E on the outside.
• FIG. 9b illustrates the jaws (40) in the closed position, the jaws being seen perpendicular to those of FIG. 9a.
• FIGS. 10a and 10b illustrate the measurement of the porosity of a nanocomposite layer E on an aluminum support P, the assembly forming a test material (53).
• FIG. 10a shows diagrammatically the nanocomposite layer E comprising a vinyl bonding layer AV and a vinyl layer V.
• FIG. 10b diagrams the device (5) for measuring the porosity, by applying a voltage of 1.5 V between the support P and a copper plate (51) serving as cathode, a blotter (52) saturated in aqueous solution of CuSO and nitric acid, being placed above the material (53).
• FIG. 11 is a diagram giving the viscosity in Pa.s on the ordinate, as a function of the shear rate in s "1 on the abscissa for a nanocomposite D dispersion, at two concentrations (1% and 2% by weight) of mineral fillers CM (curves denoted respectively Dl and D2) in the acrylic varnish V used for the tests, the solvent S being water
• CM mineral fillers
• FIGS. 12a and 12b represent the RX diagrams of phyllosilicate mineral fillers used in the dispersions according to the invention:
• curve A corresponds to the starting Cloisite 30B®
• curve B corresponds to the starting Cloisite 10A®
• curve C corresponds to Cloisite Na + ® at the start
• curve D corresponds to a nanocomposite dispersion according to the invention at 2% of the same exfoliated charge.
• said mineral filler is typically a natural or synthetic phyllosilicate, chemically treated or not.
• This type of mineral filler is known to consist of a stack of lamellae or Mo sheets of silicates a few angstroms thick (typically 1 nm in the case of a clay of the montmorillonite or bentonite type), and one of them spaced apart. the other a so-called "interlamellar" distance of approximately 1.5 nm, these sheets having a form factor L / Ec which can range from 20 to 2000.
• Said phyllosilicate can be chemically treated and include, as an intercalating agent, either quaternary ammonium ions substituted by alkyl chains, in the case of an apolar organic solvent, or quaternary ammonium ions substituted by alkyl chains typically hydroxylated in the case where said solvent is a polar organic solvent, ie alkaline ions, typically Na + , when said solvent is water or an aqueous solution of a polar organic solvent.
• said mineral filler is in the form of a powder with a particle size such that the average diameter of the agglomerates forming said powder is centered between 5 ⁇ m and 50 ⁇ m, so as to facilitate the exfoliation of the sheets.
• said exfoliation means can be chosen from dispersers, in particular those with a turbine, making it possible, typically by adjusting the speed of rotation of the turbine, to obtain a shear speed ⁇ of between a maximum value YM AX of 15000s "1 , and a minimum value YM ⁇ N of 1000 s " 1 , so as to limit the risk of breaking the exfoliated sheets or nanoparticles M, or to break them as little as possible, and to have a form factor L / Ec generally as high as possible, with an average L / Lo ratio clearly greater than 0.5, and greater than 0.7, while ensuring a high exfoliation speed typically advantageous for leading to high productivity of the industrial process.
• the duration T1 of the exfoliation step will depend in particular on the shear rate ⁇ , and will increase all the more as the shear is low. It is thus possible, at least in certain cases, to exfoliate by simple stirring in a solvent S a charge CM selected according to the invention, but in this case, the duration T1 may range for example from 20 to 30 hours.
• these turbine dispersing means are therefore "milder” - or the conditions of their use are “milder” - than conventional dispersing means such as Werner ® mixers or Banburry ® or Brabender ® which most often operate in a very viscous medium with viscosities of several hundred Pa.s, or else that ultra-fast dispersers which operate by impact with very high shear rates ⁇ which can reach or exceed 20000s "1 .
• the Applicant has observed a relationship between the shear rate ⁇ and the form factor of the exfoliated nanoparticles, all other things remaining equal, including the viscosity.
• This shear speed ⁇ can be either known or evaluated, in the case of fluid dispersions, in particular from the gradient V / e of the linear speed V between the fixed and rotating parts in said dispersing means, parts separated from a distance "e” as shown diagrammatically in FIG. 1.
• the average form factor L / Ec can be established either by transmission electron microscopy (TEM), or more simply correlated with the permeability to gases, for example to oxygen, thanks to the tortuosity model of Nielsen (Journal Macromol. Sci. 1967, p.929) shown diagrammatically in FIG.
• PE / R + CM denotes the permeability of layer E comprising the resin R as a matrix and the mineral filler CM
• P E / R denotes the permeability of layer E comprising only the resin R
• ⁇ R is the volume fraction of resin R in layer E
• ⁇ C M is the volume fraction of mineral charge CM in layer E.
• the shear rate ⁇ is between 0.33.YM A X and 0.9.YM A X, so as to reconcile the safety of dispersion by limiting the risks of reducing the form factor L / Ec, and the productivity of the process.
• said concentration Cl is typically between 0.5.C1 MAX and 0.95.C 1 MAX, with C1 M AX between 1 and 10% by weight.
• a given property may be optimum for a concentration Cl less than 0.5.C1 M AX, or even be optimum for a shear less than 0 3.
• the final concentration of the mineral filler in the final dispersion D, Cl ' is equal to C 1 (100/100 + C2), taking into account the dilution caused by the introduction of the resin R - at the concentration C2 - in nanoparticulate dispersion C.
• the time Tl during which said mineral charge CM is dispersed in said solvent S can typically be between 10 minutes and 60 minutes, but, as we have already seen it, much longer if the shear speed is lower.
• said solvent S can be a solvent, or a mixture of solvents miscible with one another, typically eliminable by evaporation, chosen from: organic solvents with less than 6 carbon atoms such as alcohols, ketones, esters or ethers for polar solvents, or solvents with less than 9 carbon atoms such as aliphatic, alicyclic or aromatic hydrocarbons for non-solvents polar, water or aqueous solutions of these organic solvents, organic solvents in the form of monomers or oligomers crosslinkable typically by irradiation, insofar as their viscosity, under the conditions of exfoliation, is close to that of usual solvents mentioned above.
• organic solvents with less than 6 carbon atoms such as alcohols, ketones, esters or ethers for polar solvents, or solvents with less than 9 carbon atoms such as aliphatic, alicyclic or aromatic hydrocarbons for non-solvents polar, water or aqueous solutions of these organic solvents
• Said resin R can then be incorporated into said nanoparticulate dispersion C in the form of a powder or a liquid composition, dispersible in said solvent.
• Said liquid composition may be an emulsion or a dispersion of resin in said solvent or in a secondary solvent miscible with said solvent.
• Said resin R can be a film-forming thermoplastic resin chosen from:
• a varnish typically vinyl, acrylic or nitrocellulose, when it is a question in particular of protecting the interior or exterior face of said support, in particular when said support comprises an aluminum foil or paper or a film of thermoplastic material, that said support is either printed or not,
• said nanoparticulate dispersion D can be treated so as to eliminate the agglomerates or aggregates of mineral filler possibly present, and of size greater than the thickness of said composite layer, ie typically 5 ⁇ m, for example by subjecting said dispersion to ultrasound, or by filtering or centrifuging said nanoparticulate dispersion.
• the exfoliation process according to the invention being relatively "gentle", it cannot be excluded that some aggregates may remain in the nanoparticulate dispersion D at the end of step b). As such aggregates would remain until the final coating, and risk forming a relief relative to the thickness of the composite layer resulting from the coating, it is generally preferable to eliminate them in particular using the means indicated above. .
• These aggregates with a dimension typically greater than 5 ⁇ m can also be optionally recycled.
• said mineral filler being able to comprise, between its sheets, quaternary ammonium ions N + R ⁇ R 2 R 3 R 4 , it is advantageous that in step a) of dispersion, there is incorporated into said solvent an auxiliary solvent at 0, 5 to 10% by weight, and preferably 1 to 5% by weight, relative to said solvent, said auxiliary solvent being chosen with a solubility parameter ⁇ s typically at least equal to ⁇ c - 1, ⁇ c being the solubility parameter, typically calculated, of said quaternary ammonium ion, said solubility parameters ⁇ s and ⁇ c being expressed in MPa 1/2 , as described in "Polymer Handbook" (Third Edition,) by J. Brandrup, EH Immergut, pages VII-524 to VII- 544.
• the ammonium ion is of the dimethyl benzyl tallow type.
• the solubility parameter ⁇ c of the corresponding amine which can be calculated by the formula p. ( ⁇ Fi) / M, where p, Fi and M denote respectively the density, the contribution of Van Krevelen, and the molar mass of the corresponding amine, has the value of 19.95 MPa 1/2 .
• the auxiliary solvent chosen is butyldiglycol which is the butyl ether of diethylene glycol whose solubility parameter ⁇ s is 20.5.
• the method according to the invention makes it possible to transform any standard varnish or coating, comprising a solvent S and a resin R, into a nanaocomposite composition or dispersion.
• the invention teaches how to choose a mineral filler CM, and, if necessary, how to choose an auxiliary solvent. It also teaches the conditions for implementing a process allowing a fully exfoliated nanocomposite dispersion. This is therefore an important object of the invention.
• Another object of the invention consists of the nanocomposite dispersion D obtained according to the invention and in which the concentration C'i in mineral filler, equal to Cl / (1 + C2), is between 1% and 5% in weight, in which the concentration C2 of resin is between 10% and 60% by weight, said dispersion having a viscosity typically between 50 and 250 mPa.s, viscosity measured under a shear rate of 100 s "1 , so to be applicable on a substrate on a reel, by coating, typically with a roller or by spraying.
• the invention makes it possible to apply said nanocomposite dispersion D to a support P to form, by coating this support P, a layer E, using standard equipment, in particular varnishers, which is encountered in the manufacture of flexible packaging based on these same supports in the form of sheets or films on reels.
• the invention is not limited to this single means of application. It is also possible to spray said nanocomposite dispersion D onto the preceding support, or onto an already shaped object, as will be indicated below.
• Another object of the invention consists of a process for coating a substrate P with the nanocomposite dispersion D according to the invention, process in which: 1 - optionally treating the surface of said substrate P on which a layer of said nanocomposite D dispersion must be applied, 2- then a layer of said nanocomposite D dispersion is applied, typically by coating or by spraying, with or without identification, after having optionally diluted with a solvent and / or having incorporated additives,
• Said substrate P can be a plastic film in a strip or reel and in which steps 1 to 3 of the method are carried out continuously with running of said strip.
• the support P can also be metal foil, typically aluminum, paper, or any multilayer material comprising a plastic film or aluminum foil or paper.
• Said substrate P can also be a shaped container, typically made of plastic, but possibly of metal (steel, tin, aluminum, copper, tin, etc.), glass or cardboard or of multilayer material, the inner surface and / or the exterior of each container being treated according to steps 1 to 3 of the method, said container being able to be chosen from: bottles, tubes, jars, boxes, drink cans, aerosols, trays, flasks, stoppers, and caps for capping or overcapping.
• a shaped container typically made of plastic, but possibly of metal (steel, tin, aluminum, copper, tin, etc.), glass or cardboard or of multilayer material, the inner surface and / or the exterior of each container being treated according to steps 1 to 3 of the method, said container being able to be chosen from: bottles, tubes, jars, boxes, drink cans, aerosols, trays, flasks, stoppers, and caps for capping or overcapping.
• this material can be chosen from polyolefins (PE, PP) or olefinic copolymers (EAA, EVA, EMA, EBA, ionomer resin, etc.), polyesters (PET, PBT ), PS, etc ...
• the surface of said substrate P can be treated by applying a treatment or a bonding layer to said substrate (Corona treatment, treatment with flame, plasma, etc.), or a primer, especially when the substrate P is a thermoplastic film or aluminum foil.
• a treatment or a bonding layer to said substrate (Corona treatment, treatment with flame, plasma, etc.), or a primer, especially when the substrate P is a thermoplastic film or aluminum foil.
• said bonding layer or the primer can comprise a resin chosen from a PU, a PEI (polyetherimide) to promote the bonding of the layer or film formed on said support from the layer of said dispersion.
• said nanocomposite layer or coating E is a surface layer or an inner layer, said inner layer being between said support and another layer covering it.
• this layer may have an inner layer, coated with a film of another material on each of its faces.
• Another subject of the invention consists of a coated substrate according to the invention and in which said resin is an EVOH resin, or a vinyl resin, or an acrylic resin, or a nitrocellulosic resin, and in general, a thermoplastic or thermosetting resin.
• said resin is an EVOH resin, or a vinyl resin, or an acrylic resin, or a nitrocellulosic resin, and in general, a thermoplastic or thermosetting resin.
• Such a coated substrate may comprise, as support, a film of thermoplastic material with a thickness between 10 and 200 ⁇ m, and a nanocomposite coating E of the surface, so as to confer on said support antistatic and / or high gas barrier properties, and / or high surface hardness, and / or high thermal resistance, and / or low porosity.
• said substrate may comprise a print, said nanocomposite coating being an outer layer covering said print, so as to give said printed substrate a high thermal resistance, so that the print is not degraded in particular when the jaws of high temperature seals are applied against said substrate.
• Step 1 after having first selected an S-CM pair, and previously determined the operating conditions, a nanoparticulate dispersion C was first prepared in a one-liter reactor equipped with a Turax® model T25 disperser, equipped a head referenced 25F. After having loaded the reactor with solvent S and with mineral load CM, the step of exfoliation of the mineral load CM in solvent S was started, at a temperature between 10 and 25 ° C.
• Step 2 a nanocomposite dispersion D was then produced in a thermostatically controlled reactor by incorporating the resin R, in liquid form or in solution in solvent S or in a solvent miscible with solvent S, or in the form of powder, with low shear stirring, typically less than 1000, generally with a Rayneri® (possibly using the Turax® at low speed of the order of 500 rpm).
• the operation was typically carried out at room temperature in the case of a resin in liquid form or in solution.
• a resin in powder form such as the EVOH resin
• the operation was carried out at a temperature between the glass transition temperature Tg of the resin R and the boiling temperature of the solvent.
• the dispersion C or D should not contain clumps of size greater than the thickness of the final layer obtained by coating on a support, thickness of the order of 2 to 5 ⁇ m.
• the dispersion C or D is treated for 20 min in an ultrasonic tank with a maximum power of 380 W operating at 1 Hz, so as to reduce the size of these clusters.
• a dispersion C or D is thus obtained, the largest clusters of which have a size of approximately 2-3 ⁇ m - and this without appreciably modifying the form factor L / Ec of the sheets.
• resin R Four different resins have been chosen as resin R, an EVOH resin, a vinyl resin, a nitrocellulose resin, and an acrylic resin, the last three resins corresponding to coatings commonly used in the field of flexible packaging.
• Step 3 the nanoparticulate dispersion D was then rolled on a support P, typically PET films of 55 ⁇ m or 12 ⁇ m, OPP of 30 ⁇ m, or aluminum foil of 10 ⁇ m or 30 ⁇ m d 'thickness, the quantity deposited being chosen, taking into account the dry extract of the nanoparticulate dispersion D, so as to obtain after drying, a film F consisting of a layer or coating E typically having 2 to 5 ⁇ m in thickness on the support P.
• a support P typically PET films of 55 ⁇ m or 12 ⁇ m, OPP of 30 ⁇ m, or aluminum foil of 10 ⁇ m or 30 ⁇ m d 'thickness, the quantity deposited being chosen, taking into account the dry extract of the nanoparticulate dispersion D, so as to obtain after drying, a film F consisting of a layer or coating E typically having 2 to 5 ⁇ m in thickness on the support P.
• drying temperatures and durations vary in particular according to the supports P and the resins R and the solvent S. It was thus generally carried out under the following conditions:
• Cloisite 10A from the company Laporte which is a modified montmorillonite comprising, between the sheets, ammonium ions substituted by a fatty chain hydrogenated in C12-C18 (chain with 12-18 carbon atoms) and by a benzyl radical,
• Cloisite 30B from the company Laporte which is a modified montmorillonite comprising, between the sheets, ammonium ions substituted by a fatty chain hydrogenated in C12-C18 and hydroxylated in position 2,
• the average form factor Lo / Ec of these mineral fillers CM is as follows
• the concentration C 1 MA X is the maximum concentration by weight in CM at which a gel is formed at a temperature of 25 ° C.
• the shear speed ⁇ is the shear evaluated according to the Couette model, as already indicated, from the speed of rotation and the geometric characteristics (radii) of the fixed and rotating parts of a model Turax ® type disperser T25 fitted with a 25F head.
• the shear speed Y M is that which leads to an acceptable exfoliation, that is to say that which leads to a compromise between a short duration of exfoliation, typically less than 2 hours and a high form factor, at least equal to 50% of
• Lo / Ec and preferably greater than 80% of Lo / Ec.
• Each nanocomposite D dispersion test carried out corresponds to a combination of a solvent S, a mineral filler CM and a resin R, the pairs S-CM being chosen from all those selected in Al.
• the RI resin is an EVOH Exceval ® resin from Kuraray, reference AQ4005. This EVOH resin belongs to the family of resins with ethylene content between 2 and 20 mol%, and dispersible in water.
• R2 resin is an acrylic resin from Croda, reference 59674.
• the resin R3 is a vinyl resin comprising a mixture of copolymers of vinyl acetyl chloride modified or not maleic acid, of acetyltributyl citrate as plasticizer.
• the resin R4 is a nitrocellulosic resin with a nitrogen index close to 12%, comprising a polyether vinyl as a plasticizing resin, and di2-ethylhexyl adipate as a plasticizer.
• step "a" the dynamic viscosity ⁇ of the nanocomposite dispersions C changes during step "a".
• the value mentioned is the dynamic viscosity at the end of step "a" of exfoliation. It is typically between 0.01 Pa.s and 10 Pa.s. at a shear speed of 100 s ' 1 .
• the coatings obtained in the coating tests E1 to E2 were even less sensitive to ambient humidity than the control coatings, so that it is not necessary to add a protective layer, which may be due simultaneously to the low level of ethylene in the EVOH resin, compared to the rates of 32 to 38% of EVOH resins for extrusion, and to the action of the mineral fillers exfoliated according to the invention.
• Oxygen permeability measurements were also made on the films of the coating tests E3 and E4. In the case of the E3 test, results were slightly lower than those of E2, and, in the case of the E4 test, corresponding to the dispersion D9 outside the invention, much lower results.
• PP films were extruded, comprising PP grafted with maleic anhydride, and comprising 0, 2, 5 and 10% by weight of CM5 mineral filler. Oxygen permeability was measured, and no significant difference in permeability was observed between the 0% CM control film and the 2% and 5% CM films. On the other hand, the 10% CM film is only slightly less permeable than the other films.
• the results of the coating tests El, E2 and those of the comparative tests T3, T4 clearly show that the application of a dispersion according to the invention comprising an exfoliated mineral filler CM, divides the permeability by approximately 10 a layer of EVOH.
• the inherent influence of EVOH appears by comparing the tests T3, T4 with the tests Tl, T2 relating to the supports alone.
• the hardness was measured in pencil, noting the hardness of the pencil which lines the surface of the coating, the range of increasing hardness of the pencils being: 6B, 5B, 4B, 3B, 2B, B,
• the dispersions according to the invention can give a film remarkable antistatic properties.
• the films coated with aciylic varnish according to the invention are approximately 5000 times less "static" than the films coated with the same control varnish.
• Tests were carried out by applying to the aluminum foil by coating the nanocomposite dispersions according to the invention - dispersions D4 based on vinyl varnish V and D4 'based on vinyl bonding varnish AV, the two dispersions being at 3% by weight of Cloisite 30B, so as to form various combinations of materials as indicated below, and in particular A1 / E87E8, the coatings E8 and ES 'being obtained respectively from dispersions D4 and D4'.
• the sliding coefficients are therefore reduced in this case by approximately 20%.
• the amplitude of roughness in ⁇ m is typically less than 0.5 ⁇ m for a standard varnish, while it can range from 1 to 3 ⁇ m for a layer of varnish formed by coating. from a dispersion according to the invention. Depending on the applications, such characteristics will be advantageous or not.
• a test was also carried out with a composite of the Al / El 1 '/ El 1 type, the coating El 1 being formed from the dispersion D7 (outside the invention) and the vinyl varnish V, and the coating EU' being similar to dispersion D7, but formed with the AV bonding varnish. No improvement was obtained compared to the reference composite Al / AV / V mentioned above.
• test E6 ' corresponds to the coating of a PET film 55 ⁇ m thick with a layer of 3 ⁇ m thick formed by coating from a nanocomposite dispersion D2 '.
• Heat sealing device 4 Heat sealing jaws 40

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