Classifications

• • 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
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/08—Layered products comprising a layer of metal comprising metal 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
  • B32B15/088—Layered products comprising a layer of metal comprising metal 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 comprising polyamides
• • 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
  • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
  • B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
• • 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
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
  • B32B15/046—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of foam
• • 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
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/18—Layered products comprising a layer of metal comprising iron or steel
• • 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
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B2266/00—Composition of foam
  • B32B2266/02—Organic
  • B32B2266/0214—Materials belonging to B32B27/00
  • B32B2266/0257—Polyamide
• • 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
  • B32B2307/00—Properties of the layers or laminate
  • B32B2307/70—Other properties
  • B32B2307/718—Weight, e.g. weight per square meter
• • 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
  • B32B2309/00—Parameters for the laminating or treatment process; Apparatus details
  • B32B2309/08—Dimensions, e.g. volume
  • B32B2309/10—Dimensions, e.g. volume linear, e.g. length, distance, width
  • B32B2309/105—Thickness
• • 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
  • B32B2605/00—Vehicles
• • 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
  • Y10T428/249921—Web or sheet containing structurally defined element or component
  • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]

Definitions

• the present invention relates to a composite structure, in particular a sandwich structure comprising a structural layer C1, a layer C2 of lightening and possibly of reinforcement, in rigid or semi-rigid foam, and possibly a structural layer C3.
• the invention relates more particularly to a composite structure comprising a layer C2 of polyamide-based foam, a method of manufacturing and a use of this structure.
• Composite structures, in particular sandwich structures are used in many fields such as aeronautics, the automobile industry, the sports industry and leisure. These structures are used to produce sporting goods such as skis or else to produce various surfaces such as special floors, partitions, vehicle bodies, billboards etc.
• Composite structures can also be used for the manufacture of veranda covers, terraces, roofs, balconies, galleries, walls (cladding) etc.
• Composite structures with an internal lightening layer of polyurethane foam are also known.
• rigid polyurethane foams tend to crumble and also have low resistance to impact and fatigue. Their processing temperature is also limited.
• the present invention therefore provides a composite structure which does not have these drawbacks, and which in particular has good properties of rigidity, lightness, recyclability.
• the present invention therefore relates to a composite structure, in particular a sandwich structure, comprising at least: • a structural layer C1 • a lightening and optionally reinforcing layer C2, of rigid or semi-rigid foam • optionally a structural layer C3, the foam being a polyamide-based foam
• the composite structure is a sandwich structure comprising two external structural layers C1 and C3, and an internal layer of lightening C2.
• the structural layer of the composite structure is preferably in the form of a plate or sheet.
• a plate can be formed from several sheets having different orientations relative to each other in order to obtain a plate having good mechanical properties.
• the plates or sheets can have variable dimensions.
• the structural layer may be made of metal such as aluminum, a metal alloy such as steel, etc.
• the plates can be lacquered or covered with any suitable coating.
• the thickness of the structural layer of the composite structure of the invention is advantageously between 0.2 and 3 mm.
• the outer layer of the composite structure of the invention can comprise several layers.
• the overall thickness of the composite structure of the invention is between 3 and 50 mm.
• the density of the foam of the structure of the invention is preferably less than
• the foam of the structure of the invention preferably has good resistance to compression, which allows it to retain its integrity and its properties during a possible crushing of the structure. This crushing can occur in certain fields of application of the structure, for example during violent shocks in particular.
• the polyamide of the invention is a polyamide of the type of those obtained by polycondensation from dicarboxylic acids and diamines, or of the type of those 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 is advantageously chosen from the group comprising PA 4.6, PA 6, PA 6.6, PA 6.9, PA 6.10, PA 6.12, PA 6.36, PA 11, PA 12 or a semi-aromatic semi-aromatic polyamide or copolyamide chosen from the group comprising polyphthalamides, and mixtures of these polymers and their copolymers.
• the polyamide is chosen from polyamide 6, polyamide 6.6, their mixtures and copolymers.
• the rigid or semi-rigid polyamide foam of the invention can be obtained according to any method known to those skilled in the art. It can be obtained by injecting gas under pressure into the polyamide in the molten state.
• the foam can also be obtained by incorporating porophores - thermally unstable fillers - into the polyamide in the molten state, which release a gas during their decomposition. It is also possible to obtain the polyamide foam of the invention by introduction into the polyamide in the molten state of compounds which dissolve in the melt, the foam being obtained by volatilization of these compounds.
• the foam can also be obtained by means of a chemical reaction releasing gas, such as carbon dioxide, for example by bringing together isocyanates and lactams as well as bases to activate the anionic polymerization.
• the polyamide foam of the invention is preferably obtained from a mixture of polyamide and polycarbonate. The foam is obtained chemically, that is to say in particular by chemical reaction between polyamide and polycarbonate.
• the polycarbonate of the mixture is advantageously a polycarbonate comprising aromatic rings of formula:
• Ri, R 2 identical or different, are hydrogen, halogen or alkyl or haloalkyl radicals comprising between 1 and 5 atoms carbon, each aromatic nucleus possibly being substituted by alkyl or haloalkyl radicals comprising between 1 and 5 carbon atoms.
• n is an integer between 40 and 300, preferably between 20 and 300.
• the molecular weight of the polycarbonate of the invention is preferably between 5000 and 80,000, more preferably between 10,000 and 40,000.
• the mixture comprises 0 , 5 to 20% by weight of polycarbonate relative to the polyamide, preferably 5 to 15% by weight.
• the mixture of polyamide and polycarbonate of the invention may also comprise, in addition to a polyamide and a polycarbonate, blowing agents which will make it possible to amplify the foaming phenomenon during the preparation of the foam from the mixture.
• blowing agents are known to those skilled in the art.
• the mixture can also include other additives useful for the subsequent preparation of the foam, such as surfactants, nucleating agents such as talc, plasticizers, etc. These additives are known to those skilled in the art.
• the mixture can also include reinforcing fillers such as glass fibers or carbonate, matifiers such as titanium dioxide or zinc sulfide, pigments, dyes, heat or light stabilizers, bioactive agents, antifouling agents, antistatic agents, flame retardants, high or low density fillers etc.
• matifiers such as titanium dioxide or zinc sulfide, pigments, dyes, heat or light stabilizers, bioactive agents, antifouling agents, antistatic agents, flame retardants, high or low density fillers etc.
• the mixture of polyamide and polycarbonate is produced according to any method known to a person skilled in the art for producing a mixture, for example by intimate mixing of polyamide and polycarbonate powders, or by mixture of polyamide and polycarbonate granules.
• the mixing can be carried out in the molten state, for example in an extrusion device.
• the foam is obtained by heating the mixture of polyamide and polycarbonate.
• the temperature reached by heating must be sufficient so that there is in particular a reaction between the polyamide and the polycarbonate, as well as a gassing which leads to the formation of foam.
• the temperature reached by heating is preferably greater than or equal to the melting temperature of the polyamide.
• a screw mixing device can be used during heating.
• a twin-screw extrusion device is used for mixing and heating.
• the foam layer C2 is generally in the form of a plate.
• the plates can be prepared according to any method known to those skilled in the art. For example when the foam is prepared by mixing and heating in a device extrusion, the plate can be shaped using a shaping device at the die outlet.
• the structural layer can comprise a thermoplastic or thermosetting polymer matrix, generally reinforced with reinforcing fibers, such as glass, carbon, aramid, polyimide or quartz fibers. , sisal, hemp, flax.
• the matrix is a thermoplastic polymer.
• the matrix is a thermoplastic polymer comprising an aliphatic and / or semi-crystalline polyamide or copolyamide, preferably chosen from the group comprising PA 4.6, PA 6, PA 6.6, PA 6.9, PA 6.10, PA 6.12, PA 6.36, PA 11 , PA 12 or a semi-aromatic semi-aromatic polyamide or copolyamide chosen from the group comprising polyphthalamides, and mixtures of these polymers and their copolymers.
• the structural layer and the lightening layer of the composite structure of the invention are made of polyamide, which has an advantage in particular for recycling this type of structure.
• the matrix of the structural layer comprises a polyamide with a star structure comprising: star macromolecular chains comprising one or more hearts and at least three branches or three polyamide segments linked to a heart , where appropriate linear polyamide macromolecular chains
• the star structure polymer is a polymer comprising star macromolecular chains, and where appropriate linear macromolecular chains.
• the polymers comprising such star macromolecular chains are for example described in the documents FR 2 743 077, FR 2 779 730, EP 0 682 057 and EP 0 832 149. These compounds are known to have an improved fluidity compared to linear polyamides .
• the polyamide with a star structure is of the type of polyamides obtained by copolymerization of a mixture of monomers comprising at least: a) monomers of general formula (I) below: b) monomers of general formulas (Ma) and (Mb) below: O II XR.-Y (Ha) or RC (Ilb) ⁇ / NH c) optionally monomers of general formula (III) below:
• - R1 is a hydrocarbon radical comprising at least 2 carbon atoms, linear or cyclic, aromatic or aliphatic and which can comprise heteroatoms
• - A is a covalent bond or an aliphatic hydrocarbon radical which can comprising heteroatoms and comprising from 1 to 20 carbon atoms
• - Z represents a primary amino function or a carboxylic acid function
• - Y is a primary amino function when X represents a carboxylic acid function or - Y is a carboxylic acid function when X represents a primary amine function
• - R2, R3 identical or different represent aliphatic, cycloaliphatic or aromatic substituted or unsubstituted hydrocarbon radicals comprising from 2 to 20 carbon atoms and which can comprise heteroatoms
• - m represents an integer between 3 and 8
• the compound of formula (I) is chosen from 2,2,6,6-tetra- ( ⁇ - carboxyethyl) -cyclohe
• the invention also relates to a process for preparing the composite structure described above.
• the method comprises a step of assembling at least the following elements: (C1 '): a structural layer or a precursor of this layer - (C2'): a layer of lightening and possibly of reinforcement, made of foam based of polyamide or a precursor of this foam - (C3 ′): optionally a structural layer or a precursor of this layer
• the precursor of the foam may be an expandable polyamide composition, for example a mixture of polyamide and polycarbonate as described below. above.
• expandable polyamide composition is meant a polyamide composition which can form a foam under certain temperature and / or pressure conditions.
• the expandable polyamide composition comprises a polyamide and a blowing agent.
• the blowing agent may be a gas which can disperse or dissolve in the polyamide in the molten state. Any gas known to a person skilled in the art which can disperse or dissolve in the polyamide can be used. The gas is preferably inert. As an example of a suitable gas in the context of the invention, there may be mentioned nitrogen, carbon dioxide, butane, etc.
• the blowing agent can also be a blowing agent. Any blowing agent known to a person skilled in the art can be used. It is introduced into the polyamide according to a method known to those skilled in the art. As an example of a blowing agent, diazocarbonamide may be mentioned.
• the blowing agent can also be a volatile compound which can dissolve in the polyamide in the molten state.
• the blowing agent may finally be a chemical compound which can react chemically with the polyamide by heating. A gas is generally generated during this reaction, gas which is at the origin of the expansion of the mixture.
• the blowing agent can for example be a polycarbonate.
• the expandable polyamide composition may be in the form of a powder, a part (plate) obtained for example by controlled injection so as to avoid the formation of foam, of mixture in the molten state, etc.
• the precursor of the structural layer may be an article comprising reinforcing fibers.
• the article can be in the form of continuous or cut threads, ribbons, mats, braids, fabrics, knits, tablecloths, multiaxials, nonwovens and / or complex shapes comprising several of the above-mentioned shapes.
• the precursor of the structural layer preferably comprises a polymer matrix, for example in the form of powder, film, etc.
• the precursor of the structural layer may be a prepreg article, i.e. a fabric impregnated with a resin, the resin comprising a curing agent for further curing by heating.
• the precursor of the structural layer is an article comprising son and / or reinforcing fibers and son and / or fibers of polymeric matrix.
• yarn is meant a monofilament, a continuous multifilament yarn, a yarn of fibers, obtained from a single type of fiber or from several types of fibers in intimate mixture.
• the continuous thread can also be obtained by assembling several multifilament threads.
• fiber is meant a filament or a set of cut, cracked or converted filaments.
• the article comprising reinforcing threads and / or fibers and threads and / or fibers of a polymer matrix may be in the form of continuous or cut threads, ribbons, mats, braids, fabrics, knits, tablecloths , multiaxials, nonwovens and / or complex shapes comprising several of the aforementioned shapes.
• Any method of assembling different layers can be used in the context of the process of the invention.
• the different elements (C1 '), (C2'), and possibly (C3 ') can be assembled simultaneously or successively, for example by gluing.
• the bonding is carried out according to any method known to those skilled in the art for assembling elements of a composite structure with several layers.
• the different elements can be glued with an adhesive film compatible with the material of the elements.
• the assembly is carried out by thermoforming or calendering of the different elements (C1 '), (C2') and possibly (C3 ') described above.
• the different elements are thermoformed or calenders simultaneously or successively.
• the layer (C1 '), layer (C3') and possibly layer (C2 ') combination can be thermoformed or calendared simultaneously. It is also possible to thermoform or calendar the layer (C1 ') and layer (C2') assembly, then thermoform or calendar the layer (C3 ') and the layer (C1') and layer (C2 ') assembly.
• This step can be carried out by heating, then cold pressing of the various elements (stamping). Generally this step is carried out hot and under pressure.
• the thermoforming methods used use low pressures (below 20 bars and possibly under vacuum), temperatures below 270 ° C, and short times (below 15 minutes). This step notably makes it possible to obtain good adhesion between the lightening layer and the structural layer.
• the temperature during thermoforming or calendering is greater than or equal to the melting temperature of the polymer matrix of the precursor of the structural layer, when this precursor includes an article comprising reinforcing fibers and a polymer matrix.
• the relatively high melting temperature of the polyamide of the foam allows the implementation of high temperatures during the preparation of composite structures, which is not possible with known foams. Indeed, the polyamide foam melts at a higher temperature than the foams of the prior art such as polyurethane foams.
• the temperature during thermoforming or calendering is preferably greater than or equal to the melting temperature of the thermoplastic polymer matrix of the structural layer, when the latter comprises a thermoplastic polymer matrix.
• the structural layer of the composite structure is a plate or a sheet comprising a thermoplastic polymer matrix
• the assembly of the foam to the structural layer can be achieved by melting the matrix during thermoforming or calendering, which inserts into the surface pores of the foam, which then acts as an adhesive by solidifying.
• thermoforming or calendering temperature is more or less equal to the temperature of the polyamide of the foam, partial melting of the foam at the point of contact of the foam and the structural layer may occur, and this part of molten foam can also act as an adhesive, by solidifying.
• the invention also relates to the use of the composite structure described above for the production of automobile or airplane parts or for the production of sporting articles such as skis or for the production of panels in the building Other details or advantages of the invention will appear more clearly in the light of the examples given below only for information.
• the test is carried out on a foam sample 20 mm in diameter and 25 mm thick, using an INSTRON 1185 device, under conditions of temperature of 23 ° C and relative humidity rate of 50%.
• Young's modulus is determined from the force-displacement curve, recorded using the device, operating at a displacement speed of 20mm / min.
• Foam density measurement test :
• the density is measured on machined samples with dimensions 100x100x15 mm. These test pieces are then weighed with a precision balance, according to standard ASTM D 3748-98.
• Example 1 Preparation of a C2 layer of polyamide foam
• Granules of PA66 marketed by the company Rhodia Engineering Plastics under the reference A 216 Naturel® (90% w / w) are mixed with polycarbonate granules marketed by the company Bayer under the reference Makrolon 2205® (10% w / w) .
• the mixture is placed in an oven overnight under partial vacuum and flushing with nitrogen. This mixture is used to feed a twin-screw extruder equipped with a lip die.
• the temperature profile of the twin screw is as follows: (in ° C) 270-280-280-280-280-280-280-280.
• the speed of rotation of the twin-screw is adjusted to 250 rev.min "1.
• the extrudate is shaped in a shaper and cooled on a transport bench before being sawn and shaped in the form of a plate, for example 10 cm wide and 1 cm thick.
• the feed rate of the extruder is 15 kg / h.
• These plates have an average density of 0.15.
• the Young's modulus of these plates is 43 , 3 MPa.
• the abscissa corresponds to the deformation (%) and the ordinate to the stress (mPa).
• polyamide foam, PMI polymethacrylimide foam breaks beyond 27% deformation.
• Matrix used 6-star polyamide, obtained by copolymerization from caprolactam in the presence of 0.5 mol% of 2,2,6,6-tetra ( ⁇ -carboxyethyl) cyclohexanone, according to a process described in document FR 2743077, comprising about 80% of star macromolecular chains and 20% of linear macromolecular chains, of melt flow index measured at 275 ° C under 1000 g of 55 g / 10 minute.
• a laminated composite is then produced by placing several elementary layers (between 2 and 10) of the fabric obtained in a mold having a plate shape, under a press with heating plates, for a period of 1 to 3 minutes, under a pressure of between 1 and 20 Bars and a temperature higher than the melting temperature of Polyamide 6 star (230-260 ° C). After cooling to a temperature of 50-60 ° C, the composite is removed from the mold. The mass rate of reinforcement is then between 60-70%.
• Example 4 Preparation of a sandwich composite structure with two external structural layers C1 and C3. and an internal lightening layer C2.
• Example 2 Two laminate composites according to Example 2 (layers C1 and C3) are placed on either side of a layer C2 of foam prepared according to Example 1. The assembly is placed between the plates of a plate press 270mm x 270mm heaters at 240 ° C for 10 minutes at 15 bar, then pressure cooled to 130 ° C and unmolded. A sandwich structure is obtained with very good integrity of the foam and good cohesion of the layers together.
• Example 5 Preparation of a sandwich composite structure with two external structural layers C1 and C3. and an internal lightening layer C2.
• Example 3 Two laminate composites according to Example 3 (layers C1 and C3) are placed on either side of a layer C2 of foam prepared according to Example 1. The assembly is placed between the plates of a plate press 270mm x 270mm heaters at 240 ° C for 10 minutes at 15 bar, then pressure cooled to 130 ° C and unmolded. A sandwich structure is obtained with very good integrity of the foam and good cohesion of the layers together.
• Example 6 Preparation of a composite sandwich structure with two external structural layers C1 and C3, and an internal layer of lightening C2.
• the assembly is placed between the plates of a press with heating plates of dimensions 270 mm ⁇ 270 mm at 240 ° C. for 10 minutes under 15 bars, then cooled under pressure to 130 ° C. and demolded.
• a sandwich structure is obtained with very good integrity of the foam and good cohesion of the layers together.

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• Laminated Bodies (AREA)
• Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
• Body Structure For Vehicles (AREA)

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• 2003
  • 2003-09-23 FR FR0311114A patent/FR2859943B1/fr not_active Expired - Fee Related
• 2004
  • 2004-09-17 RU RU2006113609A patent/RU2344041C2/ru not_active IP Right Cessation
  • 2004-09-17 US US10/573,016 patent/US20070166526A1/en not_active Abandoned
  • 2004-09-17 JP JP2006527441A patent/JP2007505772A/ja active Pending
  • 2004-09-17 KR KR1020067007588A patent/KR100814659B1/ko not_active IP Right Cessation
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  • 2004-09-17 CN CNA2004800307090A patent/CN1871126A/zh active Pending
  • 2004-09-17 EP EP04787393A patent/EP1663642A2/de not_active Withdrawn
  • 2004-09-17 CA CA 2539629 patent/CA2539629A1/fr not_active Abandoned
  • 2004-09-17 WO PCT/FR2004/002357 patent/WO2005030477A2/fr active Application Filing

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