EP2618985A1 - Multilayer plastics items with barrier properties and process for producing the same - Google Patents

Multilayer plastics items with barrier properties and process for producing the same

Info

Publication number
EP2618985A1
EP2618985A1 EP11757164.6A EP11757164A EP2618985A1 EP 2618985 A1 EP2618985 A1 EP 2618985A1 EP 11757164 A EP11757164 A EP 11757164A EP 2618985 A1 EP2618985 A1 EP 2618985A1
Authority
EP
European Patent Office
Prior art keywords
barrier properties
layer
polymer
layers
process according
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP11757164.6A
Other languages
German (de)
French (fr)
Inventor
Dirk Eulitz
Raimund Helmig
Harald Lehmann
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Kautex Textron GmbH and Co KG
Original Assignee
Kautex Textron GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Kautex Textron GmbH and Co KG filed Critical Kautex Textron GmbH and Co KG
Publication of EP2618985A1 publication Critical patent/EP2618985A1/en
Withdrawn legal-status Critical Current

Links

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
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/16—Articles comprising two or more components, e.g. co-extruded layers
    • B29C48/18—Articles comprising two or more components, e.g. co-extruded layers the components being layers
    • B29C48/21—Articles comprising two or more components, e.g. co-extruded layers the components being layers the layers being joined at their surfaces
    • 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
    • B32B1/00—Layered products having a general shape other than plane
    • 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
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B32B27/306—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising vinyl acetate or vinyl alcohol (co)polymers
    • 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
    • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
    • 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
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/36—Layered products comprising a layer of synthetic resin comprising polyesters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K15/00—Arrangement in connection with fuel supply of combustion engines or other fuel consuming energy converters, e.g. fuel cells; Mounting or construction of fuel tanks
    • B60K15/03—Fuel tanks
    • B60K15/03177—Fuel tanks made of non-metallic material, e.g. plastics, or of a combination of non-metallic and metallic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/022—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the choice of material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/02—Combined blow-moulding and manufacture of the preform or the parison
    • B29C49/04—Extrusion blow-moulding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
    • B29C49/22—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor using multilayered preforms or parisons
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C51/00—Shaping by thermoforming, i.e. shaping sheets or sheet like preforms after heating, e.g. shaping sheets in matched moulds or by deep-drawing; Apparatus therefor
    • B29C51/10—Forming by pressure difference, e.g. vacuum
    • B29C51/105—Twin sheet thermoforming, i.e. deforming two parallel opposing sheets or foils at the same time by using one common mould cavity and without welding them together during thermoforming
    • 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
    • B29K2023/0625—LLDPE, i.e. linear low 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
    • B29K2023/06—PE, i.e. polyethylene
    • B29K2023/0608—PE, i.e. polyethylene characterised by its density
    • B29K2023/0633—LDPE, i.e. low 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
    • B29K2023/06—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
    • 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
    • B29K2023/10—Polymers of propylene
    • B29K2023/12—PP, i.e. polypropylene
    • 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
    • B29K2023/16—EPM, i.e. ethylene-propylene copolymers; EPDM, i.e. ethylene-propylene-diene copolymers; EPT, i.e. ethylene-propylene terpolymers
    • 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
    • B29K2029/00—Use of polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals or derivatives thereof as moulding material
    • B29K2029/04—PVOH, i.e. polyvinyl alcohol
    • 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
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0005—Condition, form or state of moulded material or of the material to be shaped containing compounding ingredients
    • B29K2105/0032—Pigments, colouring agents or opacifiyng agents
    • 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
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/0005—Condition, form or state of moulded material or of the material to be shaped containing compounding ingredients
    • B29K2105/0044—Stabilisers, e.g. against oxydation, light or heat
    • 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
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • 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
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/06—Condition, form or state of moulded material or of the material to be shaped containing reinforcements, fillers or inserts
    • B29K2105/16—Fillers
    • 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
    • B29K2995/00—Properties of moulding materials, reinforcements, fillers, preformed parts or moulds
    • B29K2995/0037—Other properties
    • B29K2995/0065—Permeability to gases
    • B29K2995/0067—Permeability to gases non-permeable
    • 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
    • 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
    • B32B2250/00—Layers arrangement
    • B32B2250/03—3 layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2270/00—Resin or rubber layer containing a blend of at least two different polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2272/00—Resin or rubber layer comprising scrap, waste or recycling 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
    • B32B2305/00—Condition, form or state of the layers or laminate
    • B32B2305/70—Scrap or recycled 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/724—Permeability to gases, adsorption
    • B32B2307/7242—Non-permeable
    • 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
    • B32B2307/726—Permeability to liquids, absorption
    • B32B2307/7265—Non-permeable
    • 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
    • B32B2439/00—Containers; Receptacles
    • 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
    • B32B2605/08—Cars

Definitions

  • Multilayer plastics items with barrier properties and process for producing the same The present invention relates to multilayer plastics items, encompassing at least two layers based on non- polar polyolefins and encompassing, located between the said two layers, and in direct contact with the same, a layer with barrier properties with respect to hydrocarbons, and also to a process for producing the same .
  • Containers made of plastic are widely used nowadays for the transport and the storage of hazardous liquid and gaseous products, for reasons of chemical resistance, mechanical strength, good processability, specifically including processability in complex shaping processes, and low weight.
  • fuel containers made of plastic have by way of example almost completely displaced the metallic fuel containers that were previously conventional.
  • Portable or non-fixed containers such as, as for example, petrol canisters, bottles, drums and tanks for combustible liquids and the like are also nowadays almost exclusively produced from plastics.
  • the particular advantage of plastics containers is especially found in the lower weight/volume ratio, the avoidance of corrosion problems, and low-cost production.
  • impermeability to the liquids and/or gases located in the interior of the container/tank is essential.
  • plastics containers nowadays have to comply with strict emission regulations in respect of permeability to hydrocarbons.
  • Polyolefin resins e.g. polyethylenes, polypropylenes and copolymers thereof, have very good mouldability and processability together with high mechanical strength. However, their permeability to volatile non-polar organic substances, in particular hydrocarbons, is relatively high. It is therefore essential to provide appropriate treatment of containers for the transport and/or the storage of hazardous materials comprising hydrocarbons, for example petrol or diesel.
  • the barrier properties of plastics containers made of these polyolefins can be considerably improved inter alia via fluorination, coating, or plasma polymerization.
  • barrier layer (s) is/are necessarily applied on the inner and/or outer surface of the container, and thus has/have unprotected exposure to the effects of the environment. Separation and/or chemical alteration of the said barrier layer (s) can therefore occur as time passes, and this naturally leads to significant impairment of the barrier properties .
  • the polymers usually used as polymers with barrier properties for example ethylene-vinyl copolymers and polyamides
  • barrier properties for example ethylene-vinyl copolymers and polyamides
  • the non-polar base materials such as polyethylenes and polypropylenes . Even if two layers of the said materials are coextruded and "adhere" to one another in the molten state, they separate into two spatially separate layers after the cooling process or earlier.
  • Coextrusion is therefore used to introduce, between the layers made of the base materials made of low-cost polyolefins and the barrier layer made of the markedly more expensive barrier polymer, of which the layer thickness used is therefore also minimized, adhesion- promoting layers which ensure durable bonding of the otherwise incompatible polar and non-polar layers.
  • Fuel containers in the motor-vehicle sector by way of example nowadays generally have a six-layer structure obtained by means of coextrusion, encompassing (from the inside of the container to the outside) a base layer made of "virgin” HDPE, a layer of ground material, comprising or consisting of recycled material, for example regrind (in essence likewise HDPE) , an adhesion-promoting layer, a barrier layer, another adhesion-promoting layer, and another layer made of "virgin” HDPE.
  • a base layer made of "virgin” HDPE
  • a layer of ground material comprising or consisting of recycled material, for example regrind (in essence likewise HDPE)
  • an adhesion-promoting layer a barrier layer
  • another adhesion-promoting layer and another layer made of "virgin” HDPE.
  • the apparatus cost for introducing the two at least additional adhesion-promoting layers into the coextrudate for example for two additional extruders, and also other expensive reengineering of the systems used for the extrusion process, also have the effect of enormously increasing the capital expenditure costs for systems of this type.
  • Another approach provides the use of a polyaryl amide as barrier material.
  • an adhesion promoter is necessary in order to ensure stable bonding to the base material based on polyolefin.
  • the adhesion promoter is not applied in two separate layers between the base material and the barrier layer but instead is added to the base material prior to processing.
  • this process requires very large amounts of the adhesion promoter, which is likewise costly.
  • the containers produced by the process of the invention have good barrier properties with respect to hydrocarbons and moreover also have very good mechanical stability, which also applies to the strength of bond between the individual extruded layers .
  • the present invention therefore provides a process for producing a multilayer plastics item encompassing at least two extruded layers based on non-polar polyolefins and, located between the said two layers and in direct contact with the same, an extruded layer with barrier properties with respect to hydrocarbons, where the process encompasses a step for producing a tubular multilayer plastics parison in a coextrusion blow moulding system, and where the extrusion of the layer with barrier properties takes place by means of precisely one extruder from a blend which encompasses a polymer with barrier properties with respect to hydrocarbons and which encompasses a polymer with adhesion-promoting properties, and is carried out at a melt temperature at which at least some demixing of the polymer with barrier properties with respect to hydrocarbons and of the polymer with adhesion-promoting properties takes place within the blend in the extruder .
  • extruded layer based on non-polar polyolefins means an extruded layer which in terms of weight is mostly composed of polyolefins, where these can respectively involve "virgin” polyolefins, ground material (“regrind”) in which the proportion of polyolefin predominates, or a mixture of these.
  • non-polar in this sense means polyolefins which do not bear any polar groups, for example acid groups, anhydride groups, amide groups, ester groups or hydroxy groups .
  • the expression "in direct contact” means that the layer with barrier properties with respect to hydrocarbons has been bonded respectively both at its upper side and at its lower side to a layer based on non-polar olefins .
  • extruded layer means any layer which can be extruded by means of precisely one extruder in a coextrusion process, irrespective of whether it has a structure that is homogeneous in each of its dimensions.
  • different morphologies or inhomogeneities within the said layer are not extruded layers for the purposes of the present invention, even if they themselves may have a layer- like structure.
  • the polymer with barrier properties is present with non-uniform distribution within the extruded layer with barrier properties in the form of particles and mutually overlapping laminar structures.
  • This method uses only one extruder and only one blend to produce what may be called a coated/multilayer structure which achieves a barrier effect which, in what may be called a three-layer wall structure, corresponds to that provided by a known plastics container with a six- layer wall structure.
  • the expression "mutually overlapping laminar structures” means structures which are primarily parallel to the plane of the extruded layer, which are spatially limited and which preferably form, via mutual contact, a layer of coherent material of maximum continuity.
  • the melt temperature during the extrusion of the layer with barrier properties in the process of the invention is preferably in the range from 160°C to 260°C, preferably in the range from 180°C to 240°C, preferably in the range from 200°C to 225°C, with particular preference in the range from 205°C to 215°C, and in particular in the range from 208°C to 212°C.
  • the temperature is above 260°C, the two polymers mix within the extruded layer with barrier properties and the resultant layer has markedly poorer barrier properties .
  • a screw extruder without shearing section and/or mixing section is preferably used, and particular preference is given to the use of a screw extruder without shearing section and without mixing section.
  • the polyolefins of the at least two extruded layers based on polyolefin have preferably been selected independently of one another in the process of the invention from the group consisting of respectively non-polar high-density polyethylene (HDPE) , low-density polyethylene (LDPE) , linear low-density polyethylene (LLDPE) , polypropylene (PP) , ethylene-propylene copolymer and mixtures of these, and it is possible here to use either "virgin” material, or ground material (“regrind”) or else a mixture of these. It is preferable that both layers are respectively based on non-polar high-density polyethylene (HDPE) .
  • polymer with barrier properties with respect to hydrocarbons it is preferable to use a polymer with a melt flow rate of from 2 to 10 g/10 min, preferably from 3 to 5 g/10 min, at a temperature of 210°C and under a load of 2160 g (determined to ISO 1133) .
  • the density of the polymer is preferably about 1.0 to 1.3 g/cm 3 (determined to ISO 1183) .
  • the melting point of the barrier polymer used is preferably in the range from 160°C to 200°C, preferably in a range from 180°C to 190°C (determined to ISO 11357) .
  • the polymer used in the process of the invention as polymer with barrier properties with respect to hydrocarbons is preferably a polymer selected from the group consisting of ethylene-vinyl alcohol copolymers (EVOH) , polyaryl amides, polyamides (PA) , polyvinyl alcohols (PVOH) , polyethylene terephthalate (PET) and mixtures of the same.
  • the polymer with barrier properties with respect to hydrocarbons is particularly preferably an ethylene-vinyl alcohol copolymer (EVOH) and particularly preferably an ethylene-vinyl alcohol copolymer having a proportion of from 28 to 36 mol% of ethylene, based on the molecular constitution of the copolymer.
  • the layer with barrier properties comprises no polyamide alongside the ethylene-vinyl alcohol copolymer .
  • the polymer with adhesion-promoting properties has preferably been selected from the group consisting of polyolefins functionalized with polar groups, preferably polyethylenes functionalized with unsaturated carboxylic acids or with carboxylic anhydrides.
  • polymers of this type are copolymers of ethylene with unsaturated carboxylic acids or carboxylic anhydrides, e.g. acrylic acid, methacrylic acid, maleic acid, or maleic anhydride.
  • copolymers of ethylene with maleic anhydride where the copolymer preferably comprises, based on the total weight of the polymer, from 0.05 to 5% by weight of maleic anhydride, more preferably from 0.1 to 1% by weight and particularly preferably from 0.2 to 0.3% by weight of maleic anhydride.
  • the ratio of the proportion by weight of the polymer with barrier properties to the proportion by weight of the polymer with adhesion-promoting properties in the blend, based in each case on the total weight of the blend, is preferably in the range from 15:85 to 40:60, particularly preferably in the range from 20:80 to 35:75 and in particular in the range from 25:75 to 30:70.
  • the thickness of the extruded layer with barrier properties is preferably from 2 to 10%, preferably from 3 to 8% and particularly preferably from 5.5 to 7.5%, of the sum of the layer thicknesses of the said layer and of the two polyolefin layers.
  • the multilayer plastics item produced by the process of the invention can encompass, alongside the two layers based on polyolefin and the layer with barrier properties, further extruded layers which, independently of one another, have been applied via coextrusion to one or both of the polyolefin-based layers that are in direct contact with the extruded layer having barrier properties with respect to hydrocarbons.
  • preference can be given to the following layer structure in the case of fuel containers (from inside, i.e. from the side facing towards the fuel) : HPDE, extruded layer with barrier properties for the purposes of the present invention, ground material made of regrind, comprising HDPE as main constituent, black-coloured HPDE.
  • one or more extruded layers of the plastics item in particular the extruded layers based on polyolefin, comprise additives, such as fibres, fillers, pigments, antioxidants, etc., but without any restriction to these.
  • the extruded layer with barrier properties comprises no fillers such as the material known as clay.
  • a multilayer hollow plastics body for the transport or for the storage of liquid and/or of gaseous hydrocarbons, in particular of fuels, such as petrol or diesel, or an accessory for the said hollow plastics body constitutes the plastics article produced in the process of the invention, for example filler necks, pumps, filler tubes, fill-level indicators, and ventilation devices, such as valves, or fixing means, but without restriction to these.
  • the multilayer plastics item particularly preferably involves a fuel container.
  • the invention further provides multilayer plastics items encompassing at least two layers based on non- polar polyolefins and, located between the said two layers and in direct contact with the same, a layer with barrier properties with respect to hydrocarbons, where the layer with barrier properties encompasses a polymer with barrier properties with respect to hydrocarbons and encompasses a polymer with adhesion- promoting properties, and where the polymer with barrier properties is present with non-uniform distribution within the layer with barrier properties in the form of particles and mutually overlapping laminar structures.
  • the layer with barrier properties of the invention forms what may be called a three-layer structure with a concentration of barrier material in the middle, and this is the result of an extrusion process with specific demixing of the blend during the extrusion process.
  • This method gives a product with what may be called a five-layer wall structure, using only three extruders .
  • multilayer plastics items of the invention are preferably produced by the process of the invention described above, so that the two layers based on non- polar polyolefins, and the layer with barrier properties located between, and in direct contact with, the same respectively involve extruded layers.
  • the further steps or, respectively, possibilities for processing of the parison produced in the process of the invention to give the actual plastics items are known to the person skilled in the art.
  • the extrusion head used in the process of the invention can have been designed for this purpose in a known manner in the form of head with axial or radial feed, where the melt stream emerging from the extruder flows axially or radially around the mandrel .
  • the melt stream can also be deflected within the extrusion head by appropriately designed flow channels.
  • the multilayer tubular parison can be cut or divided laterally by means of separation devices, emerging in the form of sheet- or web-shaped parisons by way of a plurality of elongate, straight linear die gaps.
  • the process can also encompass the extrusion of semifinished products which take the form of sheets or webs and which are intended for thermoforming .

Abstract

The present invention relates to multilayer plastics items, encompassing at least two layers based on non- polar polyolefins and, located between the said two layers and in direct contact with the same, a layer with barrier properties with respect to hydrocarbons, and also to a process for producing the same.

Description

Multilayer plastics items with barrier properties and process for producing the same The present invention relates to multilayer plastics items, encompassing at least two layers based on non- polar polyolefins and encompassing, located between the said two layers, and in direct contact with the same, a layer with barrier properties with respect to hydrocarbons, and also to a process for producing the same .
Containers made of plastic are widely used nowadays for the transport and the storage of hazardous liquid and gaseous products, for reasons of chemical resistance, mechanical strength, good processability, specifically including processability in complex shaping processes, and low weight. In vehicle construction, fuel containers made of plastic have by way of example almost completely displaced the metallic fuel containers that were previously conventional. Portable or non-fixed containers such as, as for example, petrol canisters, bottles, drums and tanks for combustible liquids and the like are also nowadays almost exclusively produced from plastics. The particular advantage of plastics containers is especially found in the lower weight/volume ratio, the avoidance of corrosion problems, and low-cost production. Specifically in the said application sectors, impermeability to the liquids and/or gases located in the interior of the container/tank is essential. By way of example, therefore, plastics containers nowadays have to comply with strict emission regulations in respect of permeability to hydrocarbons.
Polyolefin resins, e.g. polyethylenes, polypropylenes and copolymers thereof, have very good mouldability and processability together with high mechanical strength. However, their permeability to volatile non-polar organic substances, in particular hydrocarbons, is relatively high. It is therefore essential to provide appropriate treatment of containers for the transport and/or the storage of hazardous materials comprising hydrocarbons, for example petrol or diesel. The barrier properties of plastics containers made of these polyolefins can be considerably improved inter alia via fluorination, coating, or plasma polymerization.
A general disadvantage of the surface-modification and coating processes is that the barrier layer (s) is/are necessarily applied on the inner and/or outer surface of the container, and thus has/have unprotected exposure to the effects of the environment. Separation and/or chemical alteration of the said barrier layer (s) can therefore occur as time passes, and this naturally leads to significant impairment of the barrier properties .
Current developments are therefore primarily focused on the production and construction of multilayer systems, for example by means of coextrusion processes, where polymers with barrier properties, primarily ethylene- vinyl alcohol copolymers (EVOH) and polyamides (PA) are integrated with polyolefins and other constituents to give a multilayer composite. The usual location of the barrier polymer is approximately in the middle of the container wall; a first result of this is to minimize the flexural stresses arising within the barrier polymers, which are mostly relatively brittle, when mechanical load is applied, and a second result is that the matrix material protects the barrier polymer from environmental effects. It is also possible to use coextrusion to integrate still further layers into the multilayer composite, and this method can therefore give materials with a wide variety of advantageous properties which could not be achieved by sole use of a single polymer.
However, a disadvantage here is that the polymers usually used as polymers with barrier properties, for example ethylene-vinyl copolymers and polyamides, are generally polar and do not have adhesive properties of any kind in relation to the non-polar base materials, such as polyethylenes and polypropylenes . Even if two layers of the said materials are coextruded and "adhere" to one another in the molten state, they separate into two spatially separate layers after the cooling process or earlier.
Coextrusion is therefore used to introduce, between the layers made of the base materials made of low-cost polyolefins and the barrier layer made of the markedly more expensive barrier polymer, of which the layer thickness used is therefore also minimized, adhesion- promoting layers which ensure durable bonding of the otherwise incompatible polar and non-polar layers. Fuel containers in the motor-vehicle sector by way of example nowadays generally have a six-layer structure obtained by means of coextrusion, encompassing (from the inside of the container to the outside) a base layer made of "virgin" HDPE, a layer of ground material, comprising or consisting of recycled material, for example regrind (in essence likewise HDPE) , an adhesion-promoting layer, a barrier layer, another adhesion-promoting layer, and another layer made of "virgin" HDPE.
However, the apparatus cost for introducing the two at least additional adhesion-promoting layers into the coextrudate, for example for two additional extruders, and also other expensive reengineering of the systems used for the extrusion process, also have the effect of enormously increasing the capital expenditure costs for systems of this type. Another approach provides the use of a polyaryl amide as barrier material. Here again an adhesion promoter is necessary in order to ensure stable bonding to the base material based on polyolefin. However, in this instance the adhesion promoter is not applied in two separate layers between the base material and the barrier layer but instead is added to the base material prior to processing. However, this process requires very large amounts of the adhesion promoter, which is likewise costly.
It was therefore an object of the present invention to provide, without impairment of the barrier properties of the plastics item, a simplified process which is advantageous in relation to the costs of materials and/or to capital expenditure, which rises with every extruded layer, for producing a multilayer plastics item with barrier properties. There should moreover preferably also be no impairment of the chemical resistance, heat resistance or mechanical strength of the plastics item.
Surprisingly, a process has now been found which permits production of multilayer plastics items with a barrier layer which combines a barrier property with respect to hydrocarbons with adhesion-promoting properties with respect to non-polar polyolefins and can be combined with other extruded layers (from other extruders) by means of a coextrusion process, but nevertheless can itself be extruded by means of an extruder .
The containers produced by the process of the invention have good barrier properties with respect to hydrocarbons and moreover also have very good mechanical stability, which also applies to the strength of bond between the individual extruded layers .
The present invention therefore provides a process for producing a multilayer plastics item encompassing at least two extruded layers based on non-polar polyolefins and, located between the said two layers and in direct contact with the same, an extruded layer with barrier properties with respect to hydrocarbons, where the process encompasses a step for producing a tubular multilayer plastics parison in a coextrusion blow moulding system, and where the extrusion of the layer with barrier properties takes place by means of precisely one extruder from a blend which encompasses a polymer with barrier properties with respect to hydrocarbons and which encompasses a polymer with adhesion-promoting properties, and is carried out at a melt temperature at which at least some demixing of the polymer with barrier properties with respect to hydrocarbons and of the polymer with adhesion-promoting properties takes place within the blend in the extruder .
The demixing of the two polymers of the blend with barrier properties caused by the difference in the viscosity of the two polymers at the temperature used takes place here in such a way that most of the polymer with barrier properties is disposed approximately in the middle of the extruded layer. For the purposes of the present invention, the expression "extruded layer based on non-polar polyolefins" means an extruded layer which in terms of weight is mostly composed of polyolefins, where these can respectively involve "virgin" polyolefins, ground material ("regrind") in which the proportion of polyolefin predominates, or a mixture of these. The expression "non-polar" in this sense means polyolefins which do not bear any polar groups, for example acid groups, anhydride groups, amide groups, ester groups or hydroxy groups .
For the purposes of the present invention, the expression "in direct contact" means that the layer with barrier properties with respect to hydrocarbons has been bonded respectively both at its upper side and at its lower side to a layer based on non-polar olefins .
For the purposes of the present invention, the expression "extruded layer" means any layer which can be extruded by means of precisely one extruder in a coextrusion process, irrespective of whether it has a structure that is homogeneous in each of its dimensions. In contrast, different morphologies or inhomogeneities within the said layer are not extruded layers for the purposes of the present invention, even if they themselves may have a layer- like structure.
By virtue of the demixing achieved by the process of the invention between the two polymers within the blend, the polymer with barrier properties is present with non-uniform distribution within the extruded layer with barrier properties in the form of particles and mutually overlapping laminar structures. This method uses only one extruder and only one blend to produce what may be called a coated/multilayer structure which achieves a barrier effect which, in what may be called a three-layer wall structure, corresponds to that provided by a known plastics container with a six- layer wall structure.
For the purposes of the present invention, the expression "mutually overlapping laminar structures" means structures which are primarily parallel to the plane of the extruded layer, which are spatially limited and which preferably form, via mutual contact, a layer of coherent material of maximum continuity.
The melt temperature during the extrusion of the layer with barrier properties in the process of the invention is preferably in the range from 160°C to 260°C, preferably in the range from 180°C to 240°C, preferably in the range from 200°C to 225°C, with particular preference in the range from 205°C to 215°C, and in particular in the range from 208°C to 212°C. However, if the temperature is above 260°C, the two polymers mix within the extruded layer with barrier properties and the resultant layer has markedly poorer barrier properties . For extruding of the layer with barrier properties in the process of the invention, a screw extruder without shearing section and/or mixing section is preferably used, and particular preference is given to the use of a screw extruder without shearing section and without mixing section.
The polyolefins of the at least two extruded layers based on polyolefin have preferably been selected independently of one another in the process of the invention from the group consisting of respectively non-polar high-density polyethylene (HDPE) , low-density polyethylene (LDPE) , linear low-density polyethylene (LLDPE) , polypropylene (PP) , ethylene-propylene copolymer and mixtures of these, and it is possible here to use either "virgin" material, or ground material ("regrind") or else a mixture of these. It is preferable that both layers are respectively based on non-polar high-density polyethylene (HDPE) . As polymer with barrier properties with respect to hydrocarbons, it is preferable to use a polymer with a melt flow rate of from 2 to 10 g/10 min, preferably from 3 to 5 g/10 min, at a temperature of 210°C and under a load of 2160 g (determined to ISO 1133) . The density of the polymer is preferably about 1.0 to 1.3 g/cm3 (determined to ISO 1183) . The melting point of the barrier polymer used is preferably in the range from 160°C to 200°C, preferably in a range from 180°C to 190°C (determined to ISO 11357) .
The polymer used in the process of the invention as polymer with barrier properties with respect to hydrocarbons is preferably a polymer selected from the group consisting of ethylene-vinyl alcohol copolymers (EVOH) , polyaryl amides, polyamides (PA) , polyvinyl alcohols (PVOH) , polyethylene terephthalate (PET) and mixtures of the same. The polymer with barrier properties with respect to hydrocarbons is particularly preferably an ethylene-vinyl alcohol copolymer (EVOH) and particularly preferably an ethylene-vinyl alcohol copolymer having a proportion of from 28 to 36 mol% of ethylene, based on the molecular constitution of the copolymer. In one particularly preferred embodiment, the layer with barrier properties comprises no polyamide alongside the ethylene-vinyl alcohol copolymer . The polymer with adhesion-promoting properties has preferably been selected from the group consisting of polyolefins functionalized with polar groups, preferably polyethylenes functionalized with unsaturated carboxylic acids or with carboxylic anhydrides. Examples of polymers of this type are copolymers of ethylene with unsaturated carboxylic acids or carboxylic anhydrides, e.g. acrylic acid, methacrylic acid, maleic acid, or maleic anhydride. Particular preference is given to copolymers of ethylene with maleic anhydride, where the copolymer preferably comprises, based on the total weight of the polymer, from 0.05 to 5% by weight of maleic anhydride, more preferably from 0.1 to 1% by weight and particularly preferably from 0.2 to 0.3% by weight of maleic anhydride.
The ratio of the proportion by weight of the polymer with barrier properties to the proportion by weight of the polymer with adhesion-promoting properties in the blend, based in each case on the total weight of the blend, is preferably in the range from 15:85 to 40:60, particularly preferably in the range from 20:80 to 35:75 and in particular in the range from 25:75 to 30:70.
The thickness of the extruded layer with barrier properties is preferably from 2 to 10%, preferably from 3 to 8% and particularly preferably from 5.5 to 7.5%, of the sum of the layer thicknesses of the said layer and of the two polyolefin layers.
The multilayer plastics item produced by the process of the invention can encompass, alongside the two layers based on polyolefin and the layer with barrier properties, further extruded layers which, independently of one another, have been applied via coextrusion to one or both of the polyolefin-based layers that are in direct contact with the extruded layer having barrier properties with respect to hydrocarbons. By way of example, preference can be given to the following layer structure in the case of fuel containers (from inside, i.e. from the side facing towards the fuel) : HPDE, extruded layer with barrier properties for the purposes of the present invention, ground material made of regrind, comprising HDPE as main constituent, black-coloured HPDE. It is also possible that one or more extruded layers of the plastics item, in particular the extruded layers based on polyolefin, comprise additives, such as fibres, fillers, pigments, antioxidants, etc., but without any restriction to these. However, it is preferable that the extruded layer with barrier properties comprises no fillers such as the material known as clay.
It is preferable that a multilayer hollow plastics body for the transport or for the storage of liquid and/or of gaseous hydrocarbons, in particular of fuels, such as petrol or diesel, or an accessory for the said hollow plastics body constitutes the plastics article produced in the process of the invention, for example filler necks, pumps, filler tubes, fill-level indicators, and ventilation devices, such as valves, or fixing means, but without restriction to these. The multilayer plastics item particularly preferably involves a fuel container.
The invention further provides multilayer plastics items encompassing at least two layers based on non- polar polyolefins and, located between the said two layers and in direct contact with the same, a layer with barrier properties with respect to hydrocarbons, where the layer with barrier properties encompasses a polymer with barrier properties with respect to hydrocarbons and encompasses a polymer with adhesion- promoting properties, and where the polymer with barrier properties is present with non-uniform distribution within the layer with barrier properties in the form of particles and mutually overlapping laminar structures.
The layer with barrier properties of the invention forms what may be called a three-layer structure with a concentration of barrier material in the middle, and this is the result of an extrusion process with specific demixing of the blend during the extrusion process. This method gives a product with what may be called a five-layer wall structure, using only three extruders .
These multilayer plastics items of the invention are preferably produced by the process of the invention described above, so that the two layers based on non- polar polyolefins, and the layer with barrier properties located between, and in direct contact with, the same respectively involve extruded layers. The further steps or, respectively, possibilities for processing of the parison produced in the process of the invention to give the actual plastics items are known to the person skilled in the art. The extrusion head used in the process of the invention can have been designed for this purpose in a known manner in the form of head with axial or radial feed, where the melt stream emerging from the extruder flows axially or radially around the mandrel . The melt stream can also be deflected within the extrusion head by appropriately designed flow channels. In another possible arrangement here, the multilayer tubular parison can be cut or divided laterally by means of separation devices, emerging in the form of sheet- or web-shaped parisons by way of a plurality of elongate, straight linear die gaps.
By way of example, it is therefore possible to obtain fuel containers in a known manner by means of extrusion blow moulding from the said tubular parison. As an alternative, it is also possible to cut the parison open to give at least two sheet-like semifinished products, which are then thermoformed to give half- shells and are then welded to give a hollow body, but without any restriction of the invention to these abovementioned possibilities.
The process can also encompass the extrusion of semifinished products which take the form of sheets or webs and which are intended for thermoforming .

Claims

Claims
Process for producing a multilayer plastics item, encompassing at least two extruded layers based on non-polar polyolefins and, located between the said two layers and in direct contact with the same, an extruded layer with barrier properties with respect to hydrocarbons, where the process encompasses a step for producing a tubular multilayer plastics parison in a coextrusion blow moulding system, characterized in that the extrusion of the layer with barrier properties takes place by means of precisely one extruder from a blend which encompasses a polymer with barrier properties with respect to hydrocarbons and which encompasses a polymer with adhesion- promoting properties, and is carried out at a melt temperature at which at least some demixing of the polymer with barrier properties with respect to hydrocarbons and of the polymer with adhesion- promoting properties takes place within the blend in the extruder.
Process according to Claim 1, characterized in that the polymer with barrier properties is present with non-uniform distribution within the extruded layer with barrier properties in the form of particles and mutually overlapping laminar structures .
Process according to Claim 1 or 2 , characterized in that the melt temperature is in the range from 160°C to 260°C, preferably in the range from 200°C to 225°C, with preference in the range from 205°C to 215°C, and with particular preference in the range from 208°C to 212°C.
Process according to one or more of Claims 1 to 3 , characterized in that, for extruding the layer with barrier properties, a screw extruder without shearing section and/or mixing section is used, preferably a screw extruder without shearing section and without mixing section.
Process according to one or more of Claims 1 to 4, characterized in that the polyolefins of the at least two extruded layers based on polyolefin have been selected independently of one another from the group consisting of respectively non-polar high-density polyethylene (HPDE) , low-density polyethylene (LDPE) , linear low-density polyethylene (LLDPE) , polypropylene (PP) , ethylene-propylene copolymer and mixtures of these, and both are preferably respectively non- polar high-density polyethylene (HDPE) .
Process according to one or more of Claims 1 to 5, characterized in that the polymer with barrier properties with respect to hydrocarbons is a polymer selected from the group consisting of ethylene-vinyl alcohol copolymers (EVOH) , polyaryl amides, polyamides (PA) , polyvinyl alcohols (PVOH) and mixtures of the same, preferably being an ethylene-vinyl alcohol copolymer (EVOH) and particularly preferably being an ethylene-vinyl alcohol copolymer having a proportion of from 28 to 36 mol% of ethylene, based on the molecular constitution of the copolymer.
Process according to one or more of Claims 1 to 6, characterized in that the polymer with adhesion- promoting properties has been selected from the group consisting of polyolefins functionalized with polar groups, preferably copolymers of ethylene with unsaturated carboxylic acids or with carboxylic anhydrides, and particularly preferably copolymers of ethylene with maleic anhydride.
Process according to one or more of Claims 1 to 7, characterized in that the ratio of the proportion by weight of the polymer with barrier properties to the proportion by weight of the polymer with adhesion-promoting properties in the blend, based in each case on the total weight of the blend, is in the range from 15:85 to 40:60, preferably from 20:80 to 35:75 and particularly preferably from
Process according to one or more of Claims 1 to 8, characterized in that the thickness of the extruded layer with barrier properties is from 2 to 10%, preferably from 3 to 8% and particularly preferably from 5.5 to 7.5%, of the sum of the layer thicknesses of the said layer and of the two polyolefin layers.
Process according to one or more of Claims 1 to 9, characterized in that the multilayer plastics item encompasses further extruded layers which, independently of one another, have been applied via coextrusion to one or both of the polyolefin- based layers that are in direct contact with the extruded layer having barrier properties with respect to hydrocarbons .
Process according to one or more of Claims 1 to 10, characterized in that a multilayer hollow plastics body for the transport or for the storage of liquid and/or of gaseous hydrocarbons, or an accessory for the said hollow plastics body is involved, preferably a fuel container.
12. Multilayer plastics item encompassing at least two layers based on non-polar polyolefins and, located between the said two layers and in direct contact with the same, a layer with barrier properties with respect to hydrocarbons, where the layer with barrier properties encompasses a polymer with barrier properties with respect to hydrocarbons and encompasses a polymer with adhesion-promoting properties, characterized in that the polymer with barrier properties is present with non-uniform distribution within the layer with barrier properties in the form of particles and mutually overlapping laminar structures.
Multilayer plastics item according to Claim 12, characterized in that the two layers based on non- polar polyolefins and the layer with barrier properties located between, and in direct contact with, the same respectively involve extruded layers, produced via a process according to one or more of Claims 1 to 12.
EP11757164.6A 2010-09-24 2011-08-26 Multilayer plastics items with barrier properties and process for producing the same Withdrawn EP2618985A1 (en)

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