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
  • C08J11/00—Recovery or working-up of waste materials
  • C08J11/04—Recovery or working-up of waste materials of polymers
  • C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
  • C08J11/08—Recovery or working-up of waste materials of polymers without chemical reactions using selective solvents for polymer components
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/02—Separating plastics from other materials
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F6/00—Post-polymerisation treatments
  • C08F6/06—Treatment of polymer solutions
  • C08F6/12—Separation of polymers from solutions
• • 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
  • C08J3/12—Powdering or granulating
  • C08J3/14—Powdering or granulating by precipitation from solutions
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
  • B29B17/0412—Disintegrating plastics, e.g. by milling to large particles, e.g. beads, granules, flakes, slices
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/02—Separating plastics from other materials
  • B29B2017/0203—Separating plastics from plastics
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/02—Separating plastics from other materials
  • B29B2017/0213—Specific separating techniques
  • B29B2017/0293—Dissolving the materials in gases or liquids
• • 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
  • B29B17/00—Recovery of plastics or other constituents of waste material containing plastics
  • B29B17/04—Disintegrating plastics, e.g. by milling
  • B29B2017/0424—Specific disintegrating techniques; devices therefor
  • B29B2017/0476—Cutting or tearing members, e.g. spiked or toothed cylinders or intermeshing rollers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/06—PE, i.e. polyethylene
  • B29K2023/0608—PE, i.e. polyethylene characterised by its density
  • B29K2023/065—HDPE, i.e. high density polyethylene
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
  • B29K2023/00—Use of polyalkenes or derivatives thereof as moulding material
  • B29K2023/04—Polymers of ethylene
  • B29K2023/08—Copolymers of ethylene
  • B29K2023/086—EVOH, i.e. ethylene vinyl alcohol copolymer
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29L—INDEXING SCHEME ASSOCIATED WITH SUBCLASS B29C, RELATING TO PARTICULAR ARTICLES
  • B29L2031/00—Other particular articles
  • B29L2031/712—Containers; Packaging elements or accessories, Packages
  • B29L2031/7172—Fuel tanks, jerry cans
• • 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
  • C08J2329/00—Characterised by the use of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an alcohol, ether, aldehydo, ketonic, acetal, or ketal radical; Hydrolysed polymers of esters of unsaturated alcohols with saturated carboxylic acids; Derivatives of such polymer
  • C08J2329/02—Homopolymers or copolymers of unsaturated alcohols
  • C08J2329/04—Polyvinyl alcohol; Partially hydrolysed homopolymers or copolymers of esters of unsaturated alcohols with saturated carboxylic acids
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/52—Mechanical processing of waste for the recovery of materials, e.g. crushing, shredding, separation or disassembly
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/62—Plastics recycling; Rubber recycling

Definitions

• the present invention relates to a process for the recovery of a vinyl alcohol polymer in solution as well as to vinyl alcohol polymer particles capable of being obtained by this process.
• Vinyl alcohol polymers are widely used in industries such as textiles, adhesives, packaging, stationery ... where their excellent resistance to solvents and greases, as well as their adhesive and barrier properties are appreciated.
• these polymers have the particularity of being soluble in water, which constitutes a drawback for many applications (in particular in the presence of moisture) but constitutes on the other hand an advantage from the point of view of their recycling by the solvent route, aqueous solutions with little or no pollution that can be used for this purpose.
• These polymers are generally made from vinyl acetate polymers by saponification using methanol. At the end of this saponification, a solution or a polymer gel is generally obtained, which are then treated by suitable methods to make them into polymer particles.
• patent application EP 1179547 discloses a method for treating alcoholic solutions of EVOH avoiding the formation of gels and consisting in substituting part of the alcohol with water in a suitable device.
• a solution of EVOH is thus obtained in a water / alcohol mixture which is easier to process by spinning (extrusion of rods in a bath containing a water / alcohol mixture).
• This last stage of the process remains delicate despite everything (the composition of the bath must be kept constant) and the product obtained requires a long drying time.
• this process involves large quantities of liquid, which generally has to be regenerated.
• the Applicant has therefore attempted a simple recovery of the EVOH in solution in water / ethanol mixtures by azeotropic distillation of the latter (as described in application EP 945481 in the name of SOLVAY). However, even when proceeding under vacuum, there is a solidification of the whole. Recovery of the polymer by atomization (as described in the pending application FR 0116070 in the name of SOLVAY) has no more solved the problem, a polymer crust being obtained and not particles of regular particle size.
• the object of the present invention is therefore to provide a process for recovering a polymer of vinyl alcohol in solution which is simple, rapid and nevertheless makes it possible to obtain particles of particle size suitable for the conventional implementation processes.
• the present invention relates to a process for recovering a vinyl alcohol polymer in solution in a solvent, according to which: (a) the polymer solution is transformed into a gel (b) water is added frost obtained
• the gel is mechanically broken up to form particles of polymer suspended in a liquid comprising the solvent and the water
• the vinyl alcohol polymer whose recovery is targeted by the process according to the present invention is by definition a polymer containing monomeric units of vinyl alcohol type.
• These are generally (co) polymers obtained by partial or almost total hydrolysis (saponification) of polymers containing monomeric units of vinyl acetate type.
• These polymers (and their hydrolyzed counterparts) can either consist solely of vinyl alcohol and / or vinyl acetate monomers (case of polyvinyl alcohols (PVA) proper or partially hydrolyzed polyvinyl acetates (PVAc)) or include another monomer such as Pethylene for example.
• the polymer does not contain too many -OH groups, otherwise it becomes water-soluble and the process according to the present invention is therefore more difficult to apply.
• the process according to the present invention has given good results in the particular case of EVOH resins.
• the ethylene content is preferably greater than or equal to 20%, or even 25% so that the polymer is not water-soluble.
• the process according to the invention gives good results with the resins available commercially and having an ethylene content ranging from 27 to 44 mol%.
• the process according to the present invention also applies to mixtures of polymers as described above (PVA, PVAc at least partially hydrolyzed, EVOH) in solution.
• the solvent in which the vinyl alcohol polymer is dissolved is generally a liquid having a solubility parameter (a definition and experimental values of which are given in "Properties of Polymers",
• the solvent preferably comprises an alcohol and in particular, an alcohol having a solubility parameter close to 20 (methanol, ethanol, propanol, etc.).
• ethanol gives good results, and this more particularly when the polymer is EVOH.
• Water / alcohol mixtures are generally preferred and in particular with alcohols having a solubility parameter close to 20.
• the water / ethanol mixture often gives good results (especially in the case of EVOH) and is often used for reasons of toxicity in particular.
• Dissolving the EVOH in a water / ethanol mixture having an ethanol content of 30 to 70% by weight gives good results; however, it is faster for an ethanol content of approximately 50 to 60%.
• the method according to the present invention advantageously applies to a solution of vinyl alcohol polymer heated above room temperature, for example at 60 ° C. At this temperature, the concentration can be greater than or equal to 5% by weight (relative to the total weight of solution), or even 10%. However, it will advantageously not exceed 30% by weight, or even 20%.
• the polymer solution is transformed into a gel, ie. into an elastic solid where the polymer molecules form a network with tangled points. Unlike the case of crosslinked polymers, these entanglement points are links of physical and non-chemical origin, and therefore, simply places of higher polymer concentration.
• a gel which is similar to a crystallization phenomenon (and therefore includes a germination step and a growth step), can be induced by a decrease in temperature and / or addition of a non-solvent.
• a decrease in temperature gives good results.
• we will avoid going below 0 ° C because the gels obtained are then too elastic to be broken mechanically.
• the addition of a sowing agent to the solution before or during the formation of the gel makes it possible to increase its speed of formation and also makes it possible to avoid excessive cooling, often unwanted for economic reasons.
• seeding agents mention may be made of polymer powder (for example of the same nature as that to be recovered), precipitated calcium carbonate, etc. The person skilled in the art will take care to optimize the setting temperature. gel and the type of germination (sowing) to obtain the desired grain morphology and duration of the process.
• step (b) the gel obtained is added with water. It is then, during step (c), mechanically broken, ie transformed into a suspension of polymer particles by any suitable means and / or device such as a grinder or an agitator.
• any suitable means and / or device such as a grinder or an agitator.
• an agitator with an adequate morphology and rotating at an appropriate speed (factors easily determinable by those skilled in the art) gives good results.
• step (c) At the end of step (c), we are in the presence of a dispersion of polymer particles in a liquid comprising the solvent and water.
• the polymer particles can then be separated from this mixture by any suitable means (evaporation, centrifugation, etc.).
• a distillation preferably azeotropic
• Such a method is very suitable in the case of water / alcohol mixtures and in particular, in the case of the water / ethanol mixture.
• the liquid is a water / alcohol mixture from which the alcohol is removed by azeotropic distillation.
• care will be taken in certain cases (as with EVOH for example) to carry out this distillation under vacuum (ie at a pressure lower than atmospheric pressure, even lower or equal to 300 mbar) in order to be able to reduce the temperature.
• EVOH there is in particular a solidification from 67 ° C; also, in practice, care will be taken that the temperature is less than or equal to 65 ° C.
• the pressure it will advantageously be less than or equal to 250 mbar.
• EVOH particles are then collected suspended in water. These particles and water can then be separated by any appropriate means (centrifugation and / or drying, etc.). Alternatively, the dispersion can be used as it is in coating applications for example.
• the process is preferably carried out with stirring and at a shear rate adapted to the desired grain size.
• the Applicant has in fact found that the fact of working with stirring makes it possible to reduce the size of the grains, presumably by inhibiting agglomeration between primary particles.
• the process according to the present invention can be integrated into any process involving the recovery of a vinyl alcohol polymer from a solution.
• it can be part of a process for recycling such polymers.
• the method according to the present invention is applied to a polymer solution obtained by shredding at least one article comprising at least one polymer of vinyl alcohol, (such as EVOH) into fragments of a average size from 1 cm to 50 cm in case it exceeds these dimensions and by putting the article fragments in contact with a solvent capable of dissolving the polymer but not any other constituents of the article.
• a solvent capable of dissolving the polymer but not any other constituents of the article A water / alcohol mixture, and in particular water / ethanol gives good results.
• the polymer solution is first, if necessary, rid of these other constituents (by filtration for example) before being transformed into gel.
• Such a recycling process can be continuous or discontinuous (by batch). It is preferably continuous.
• An important advantage of the method according to this variant of the invention is that it can in most cases operate in a closed loop, without generating rejects. In fact, the water / solvent mixture collected during the recovery of the polymer particles can be recycled to the step of dissolving the polymer and / or breaking the gel by optimizing the flows.
• An interesting case to which the method according to the invention can be applied is that of recycling fuel tanks based on HDPE (high density polyethylene) having an EVOH layer and, more particularly, of waste resulting from the manufacture of such coextrusion-blowing fuel tanks.
• this waste (or “flash”) is currently reused as it is in one of the layers of the reservoir or subjected to a preliminary treatment by tribelectricity, by means of elimination of the fraction rich in EVOH.
• this fraction contains around 25% EVOH which it would be interesting to be able to recover for obvious economic reasons.
• This recovery can be done using the method described above, ie by operating the selective dissolution of the EVOH and by treating this solution by the method described above. Consequently, according to a particularly advantageous variant, the method according to the present invention relates to a method for recycling waste from fuel tanks comprising PHDPE and EVOH, according to which:
• step (a) the waste is subjected to a triboelectric treatment to obtain a fraction poor in EVOH and a fraction richer in EVOH
• step (b) the 2 fractions obtained in step (a) are separated
• the solution is filtered to remove the HDPE and optionally the EVOH and the other undissolved constituents (e) the solution is transformed into a gel
• the solvent used is an ethanol / water mixture having an ethanol content of 30 to 70% by weight. It is also possible, during step (h), to carry out azeotropic distillation at 65 ° C. and under 250 mbar. Finally, during step (i), the suspension of EVOH in water can be subjected to centrifugation followed by drying.
• the process according to the present invention makes it possible to obtain a very fine and regular powder formed from vinyl alcohol polymer particles.
• the size of the particles is expressed by the "equivalent diameter" that a theoretical sphere would have behaving in the same way as the particle under consideration.
• Equivalent sphere The distribution of the equivalent diameters of these spheres is adjusted to theoretical laws (e.g. the law of normal distribution or of
• the fineness is characterized by a position parameter (e.g. the diameter median or mean diameter) and particle size heterogeneity by a dispersion parameter (eg, range (called “span”) or standard deviation).
• position parameter e.g. the diameter median or mean diameter
• dispersion parameter e.g, range (called “span" or standard deviation
• the particles obtained have their largest dimension less than or equal to 100 ⁇ m, and preferably, less than or equal to 70 ⁇ m. This dimension is however generally greater than or equal to 1 ⁇ m, or even 5 ⁇ m.
• “larger dimension” is meant the length in the case of filiform or oblong particles, and the largest diameter in the case of substantially spherical particles.
• the size of the particles can be influenced by the presence of agitation during the evaporation step (azeotropic distillation) of the solvent.
• the method described above makes it possible to obtain particles having an equivalent diameter preferably less than or equal to 100 ⁇ m and, in particular, less than or equal to 70 ⁇ m.
• the polymer particles obtained by the process described above also have a narrow particle size dispersion.
• the span is less than 5 and even more preferably it is less than 3.
• Such particles can be used as such in certain applications such as coating.
• these particles can be granulated in an extruder or, more advantageously, sintered so as to avoid thermal aging of the polymer.
• the invention also relates to a multilayer fuel tank comprising in the barrier layer the EVOH obtained by the method described above.
• the present invention is illustrated in a nonlimiting manner by the following examples and counterexamples.
• Waste from the production of petrol tanks containing approximately 25% by weight of EVOH (EVAL® F 101 A) and 75% by weight of HDPE (ELTEX® RSB 714 from SOLVAY) was brought into contact with an ethanol / water mixture 70/30 by weight at 60 ° C. until a solution containing approximately 10% by weight of EVOH is obtained, ie for 45 min. This solution was cooled to 5 ° C for 90 min to cause gel formation. This gel was then added with 120 g of water and was mechanically broken using a counter-paddle agitator rotating at the speed of 300 revolutions / min. The suspension of particles obtained was brought to 60 ° C.
• Example 2 A solution of EVOH in an ethanol / water mixture was obtained as in Example 1. However, it was directly subjected to the evaporation of the ethanol instead of transforming it into a gel beforehand. As the ethanol evaporated, the solution solidified to form a block of EVOH saturated with solvent. Comparative example 4
• a 5% solution of EVOH (in an ethanol / water mixture at 70/30) was obtained according to a route identical to that of Example 1 and was subjected to atomization at a temperature of approximately 65 ° C. and under a pressure of around 250 mbar. To do this, the hot solution was injected via an atomizer into the top of an atomization chamber and water vapor was injected from the bottom. A sticky EVOH crust was collected. Various lower pressures and temperatures were tested, as well as various vapor flow rates, solvent compositions and EVOH concentrations, without significant influence on the morphology of the EVOH collected.
• a 30% solution of EVOH (in a 70/30 ethanol / water mixture) was obtained according to a route identical to that of Example 1 and was subjected to spinning in a bath containing water and brought to a temperature of 4 ° C. A wire of 2.5 mm diameter was obtained, which was too elastic to be granulated. It was therefore subjected to drying (24 hours at 60 ° C. under vacuum) but it then became too brittle to granulate it.

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• Chemical & Material Sciences (AREA)
• Medicinal Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Engineering & Computer Science (AREA)
• Life Sciences & Earth Sciences (AREA)
• Sustainable Development (AREA)
• Mechanical Engineering (AREA)
• Environmental & Geological Engineering (AREA)
• Processes Of Treating Macromolecular Substances (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Containers Having Bodies Formed In One Piece (AREA)

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• 2003
  • 2003-03-14 FR FR0303209A patent/FR2852319B1/fr not_active Expired - Fee Related
• 2004
  • 2004-03-11 JP JP2006504682A patent/JP2006520415A/ja active Pending
  • 2004-03-11 US US10/549,099 patent/US20060223896A1/en not_active Abandoned
  • 2004-03-11 WO PCT/EP2004/002634 patent/WO2004081094A1/fr active Application Filing
  • 2004-03-11 EP EP04719452A patent/EP1606341A1/de not_active Withdrawn

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