Patent Description:
The present invention further relates to single-layer containers consisting of one layer made of said polymer blend composition, and the method for producing the same.

Plastic containers for the transport of hazardous substances need to display three major technical features to be considered suitable for said purpose:.

For hazardous substances having a flash point ≤ <NUM> indeed, the barrier proprieties given by HDPE are generally insufficient, and other materials need to be combined with the polyolefine in order to produce an efficient plastic container.

At the present time, several are the technologies known to the state of the art for the provision of a high barrier HDPE container for the collection of hazardous substances.

In <CIT> an in situ multi-layer co-extrusion blow moulding is described, providing for a bi-layered container comprising an outer and an inner layer.

Said inner layer comprises a polyamide homopolymer and a maleic grafted polyethylene (MAgPE) coupling agent, while said outer layer comprises HDPE, a maleic grafted polyethylene coupling agent and the regrind material obtained from the leftover of said outer and inner layers.

<CIT> discloses a thermoplastic resin composition, and the thermoplastic resin articles thereof, comprising a modified polyolefine, a barrier resin and a polyolefine, wherein said barrier resin and said polyolefine have a specific melt viscosity ratio ranging between <NUM> and <NUM>, when said melting viscosities are measured at a shear rate of <NUM> and at a temperature ranging between MP + <NUM> - MP + <NUM>, with MP being the melting point of said barrier resin.

<CIT> further describes thermoplastic resin articles comprising a layer made of the thermoplastic resin composition mentioned above.

<CIT> discloses a nanocomposite material comprising a plastic matrix and a mineral inorganic additive in nanoparticles, e.g., Montmorillonite, which can be user for the manufacture of oriented products, such as containers.

<CIT> describes a multi-layer container for the transport of hazardous substances, displaying high barrier properties, in which an additional reinforcing layer improves the container physical strength.

There is the need to find a technology suitable for the production of plastic containers for the transport of hazardous substances, providing for high barrier properties and high impact and chemical-resistance.

An object of the invention is to provide a polymer blend composition suitable for the production of mono-layer containers, displaying excellent barrier properties, chemical and impact resistance, when compared to the containers of the prior art.

A further object of the present invention is to provide a simple economic process for the manufacture of plastic containers, easily applicable to commercial materials and valid blow moulding machines, without the need of high cost modifications of production plants.

It is an additional object of the present invention to provide single-layer containers consisting of one layer made of said polymer blend composition, that are cost-effective and easy to produce.

The production of a single-layer container with implemented barrier properties is not new to the state of the art, but it has never been accomplished as simply as the process proposed with the present invention.

One object of the present application is a single-layer container consisting of one layer made of a polymer blend composition consisting of <NUM>-<NUM>% by weight of a homopolymer or copolymer of ethylene, <NUM>-<NUM>% by weight of a polyamide homopolymer, <NUM>-<NUM>% by weight of maleic anhydride grafted polyethylene (MAgPE), in combination with suitable additives.

The homopolymer or copolymer of ethylene is preferably a high density polyethylene. Said high density polyethylene has a density preferably ranging between <NUM> - <NUM>/cm3.

Even more preferably said high density polyethylene is selected from the group consisting of high density polyethylene homopolymers, high density ethylene/hexane copolymers or mixtures thereof.

Suitable high density polyethylene hydrocarbon polymers are even more preferably characterised by:.

Suitable homopolymer or copolymer of ethylene that can be used for the polymer blend are those available on the market with the commercial name Lupolen <NUM> Z (Basell Polyolefines), Marlex® HXM <NUM> (Chevron Philips Chemical Company), HDPE <NUM> (Total refining & Chemicals), RIGIDEX® HM5420XPH (INEOS Olefines and Polymers Europe), Polyethylene HDPE <NUM> UV (Total petrochemicals).

The polyamide homopolymer used in the aforementioned polymer blend is preferably polyamide <NUM>.

Suitable polyamide <NUM> suitable for the polymer blend composition according to the present invention are more preferably characterised by:.

More preferably, suitable polyamide <NUM> is for example the one available on the market under the trade name of Grilon F <NUM> nat <NUM> (EMS-GRIVORY | a unit of EMS-CHEMIE AG).

The polymer blend composition further comprises Maleic Anhydride grafted Polyethylene (MAgPE), a modified polyethylene, functionalised with the anhydride of the unsaturated carboxylic maleic acid.

In a preferred embodiment, the MAgPE suitable for the polymer blend composition of the present invention has a density ranging between <NUM>-<NUM>/cm<NUM>, a mass flow rate ranging between <NUM>-<NUM>/<NUM> at <NUM>/<NUM>, a melting point ranging between <NUM>-<NUM>, and a maleic anhydride graft level ranging between <NUM>-<NUM>% by weight on the total weight of the MAgPE.

A suitable MAgPE is for example the one available in the market under the commercial name of DuPont™ Fusabond® E MB100D (Dupont Packaging & Industrial Polymer). The polymer blend composition comprises other suitable additives, such as antistatics, colours, UV protection-agents (antiUV), compatibilisers, nucleation agents.

The aforementioned polymer blend composition, in view of the specific selection of components and concentrations, allows the production of plastic containers for the transport of hazardous substances displaying superior barrier properties, chemical and impact resistance when compared to the plastic containers of the state of the art.

The polymer blend composition is employed to manufacture monolayer containers, for storage and collection of liquid or gel hazardous substances.

The polymer blend composition is particularly advantageous for the production of plastic containers suitable for example for the storage and collection of petroleum-based products, aromatic solvents, aliphatic solvents, ketones, kerosenes, alcohols and commercially based products such as paints, pesticides and herbicides that are dissolved in such solvents.

Advantageously the barrier layer according to the present invention provides good barrier properties for hydrocarbon materials even more preferably against the following test materials: Trichloroethylene (Flash Point (FP) <NUM> degC), Cyclohexanone (FP <NUM> degC), Hexane (FP -<NUM> degC), Propanol (FP <NUM> degC)) & Xylene (FP <NUM> degC).

The single-layer container preferably has a volume ranging between <NUM> and <NUM> and, in relation to the aforementioned volumes, a thickness ranging between <NUM> and <NUM>.

Said single-layer container is preferably produced by a method comprising the following steps:.

Preferably, the leftover material obtained from each production cycle of the aforementioned method is added to phase a. and dry blended together with the other polymers.

More precisely, according to a preferred embodiment, said single-layer container comprises <NUM>-<NUM>% by weight of regrinded material from said one layer.

With an explicative but not limitative purpose, we provide herewith two examples of the polymer blend composition employed for the production of the single-layer container according to the present invention.

Example <NUM>: Single-layer container according to the present invention, characterised by a total weight of <NUM>, a volume of <NUM> and a thickness of <NUM>-<NUM>.

A polymer blend composition suitable for the production of high-volume multi-layer containers, a simple economic process for the manufacture of plastic containers and multi-layer containers comprising one layer made of said polymer blend composition, which are not object of the present invention, are herewith disclosed by means of the following closures:.

The polymer blend composition, not belonging to the present invention, comprises <NUM>-<NUM>% by weight of a homopolymer or copolymer of ethylene, <NUM>-<NUM>% by weight of a polyamide homopolymer, <NUM>-<NUM>% by weight of maleic anhydride grafted polyethylene (MAgPE) and <NUM>-<NUM>% by weight of antistatic compound on the total weight of the polymer blend composition, in combination with suitable additives.

The homopolymer or copolymer of ethylene is preferably a high density polyethylene. Said high density polyethylene employed for the aim of the present invention has a density ranging preferably between <NUM> - <NUM>/cm<NUM>.

Suitable high density polyethylene polymers are even more preferably characterised by:.

Suitable high density polyethylene that can be used are those available on the market with the commercial name of Lupolen <NUM> AGUV <NUM> (Basell Polyolefines), Rigidex® HM4560UA (Ineos Polyolefins), Polyethylene HDPE <NUM> UV (Total petrochemicals).

The polyamide homopolymer used in the polymer blend composition, not belonging to the present invention, is preferably polyamide <NUM>.

Suitable polyamide <NUM> are more preferably characterised by:.

A suitable polyamide <NUM> polymer is for example the one available on the market with the commercial name of Grilon F <NUM> nat <NUM> (EMS-GRIVORY | a unit of EMS-CHEMIE AG).

The polymer blend composition of the present invention further comprises Maleic Anhydride grafted Polyethylene (MAgPE), a modified polyethylene, functionalised with the anhydride of the unsaturated carboxylic maleic acid.

In a preferred embodiment, the MAgPE suitable for the polymer blend composition, not belonging to the present invention, has a density ranging between <NUM>-<NUM>/cm<NUM>, a mass flow rate ranging between <NUM>-<NUM>/<NUM> at <NUM>/<NUM>, a melting point ranging between <NUM>-<NUM>, and a maleic anhydride graft level ranging between <NUM>-<NUM>% by weight on the total weight of the MAgPE.

A suitable MAgPE is the one available in the market with the commercial name of DuPont™ Fusabond® E MB100D (Dupont Packaging & Industrial Polymer).

An antistatic compound is furthermore contained in the polymer blend composition not according to the present invention.

An antistatic compound is defined as a material having a resistance R<NUM> comprised between <NUM><NUM> Ω < R<NUM> < <NUM><NUM> Ω.

Suitable antistatics employed are most preferably selected from the group consisting of polyamide-polyether block amide mixtures.

In general sense a polyether block amide (polyetheresteramide) or PEBA is a block copolymer obtained by polycondensation of a carboxylic acid polyamide (PA6, PA11, PA12) with polyoxyalkylene glycol (Polytetramethylene glycol PTMG; PEG). PEBA is a high performance thermoplastic elastomer, displaying lower density among TPE, superior mechanical and dynamic properties (flexibility, impact resistance, energy return, fatigue resistance) as well as being able to keep these properties at low temperature (lower than -<NUM>).

Polyamide/polyether block amide mixtures are polymeric systems comprising polyamide and said thermoplastic PEBA elastomers.

Among the preferred polyamide/polyether block amide mixtures, most preferably the one employed in the purpose of the polymer blend composition not belonging to the present inventions is the polymeric system known with the trade name of IRGASTAT® P18, produced from Ciba Specialty Chemicals, and providing for a permanent antistatic effect.

In another preferred embodiment, the polymer blend composition disclosed in the present application can eventually comprise other additives, such as colour, UV protection-agents (antiUV), compatibilisers, nucleation agents.

By hazardous substance is meant any of the substances belonging to classes <NUM>-<NUM>, <NUM>-<NUM> provided by "The Recommendations on the Transport of Dangerous Goods", said classes corresponding respectively to Flammable Liquids; Flammable solids, substances liable to spontaneous combustion, substances which, on contact with water, emit flammable gases; Oxidizing substances and organic peroxides; Toxic and Infectious substances; Corrosive substances; Miscellaneous dangerous substances and articles, including environmentally hazardous substances. (http://www. org/fileadmin/DAM/trans/danger/publi/unrec/rev19/R ev19e_Vol_I.

The polymer blend composition is employed to manufacture inner containers for Intermediate Bulk Containers (IBC) for storage and collection of liquid or gel hazardous substances.

Is here furthermore disclosed a multi-layer container comprising a barrier layer made of the polymer blend composition and at least one further layer comprising HDPE.

Advantageously the barrier layer disclosed provides good barrier properties for hydrocarbon materials even more prefebably against the following test materials: Trichloroethylene (Flash Point (FP) <NUM> degC), Cyclohexanone (FP <NUM> degC), Hexane (FP -<NUM> degC), Propanol (FP <NUM> degC)) & Xylene (FP <NUM> degC).

Even more preferably, said at least one further layer contains <NUM>-<NUM>% by weight of HDPE, <NUM>-<NUM>% of an antistatic compound, <NUM>-<NUM>% of additives, said additives being preferably selected among compatibilisers, colours and antiUV.

In a first preferred embodiment, the multi-layer container is constituted by three layers: the barrier layer made of the polymer blend disclosed above; a first layer made of HDPE; a second layer made of HDPE.

The three layers comprise an inner layer, an outer layer and an intermediate layer arranged between the inner layer and the outer layer. The inner layer is designed to contact the hazardous substance stored in the multi-layer container.

In said first preferred embodiment, said first layer is the inner layer, said second layer is the outer layer, and said barrier layer is the intermediate layer, arranged between said first layer and second layer.

In a second preferred embodiment, the multi-layer container is constituted by three layers: the barrier layer made of the polymer blend composition; a first layer made of HDPE; a second layer comprising <NUM>-<NUM>% of HDPE, <NUM>-<NUM>% of an antistatic compound, preferably Irgastat ® P18, and <NUM>-<NUM>% of additives, preferably <NUM>% of compatibilizer, <NUM>% antiUV and, optionally, a colour masterbatch.

Even more preferably said compatibilizer is Lotader AX <NUM>.

In said second preferred embodiment, said first layer is the inner layer, said second layer is the outer layer and said barrier layer is the intermediate layer, arranged between the first and the second layers.

Advantageously, the presence of MAgPE in the polymer blend composition according to the present invention provides for a good adhesion between the three layers, without the need to introducing an additional adhesive layer.

Even more preferably, said barrier layer of said multi-layer container comprises <NUM>-<NUM>% by weight of regrinded material from said barrier layer and from said at least one further layer.

More precisely, according to a preferred embodiment, said barrier layer comprises <NUM>-<NUM>% by weight of regrinded material from said barrier layer, said first layer and said second layer.

Whether present, said antistatic compound comprised within said at least one further layer is preferably the same antistatic compound comprised in the polymer blend composition.

The multi-layer container preferably has a volume ranging between <NUM> and <NUM>, in view of the aforementioned volumes, a total weight ranging between <NUM> and <NUM>, wherein the outer layer has a weight preferably ranging between <NUM> and <NUM>, the inner and intermediate layers have, singularly, a weight preferably ranging between <NUM> and <NUM>.

Moreover, a method for producing the multi-layer container, not belonging to the present invention, is herewith described and comprises the steps of:.

Preferably, the leftover material obtained from each production cycle of the aforementioned method is added to phase i. and dry blended together with the other polymers.

With an explicative but not limitative purpose, we provide herewith two examples of the polymer blend composition employed for the production of the multi-layer container not belonging to the present invention.

Claim 1:
A single-layer container for the transport of hazardous substances consisting of one layer made of a polymer blend composition consisting of
<NUM>-<NUM>% by weight of a homopolymer or copolymer of ethylene,
<NUM>-<NUM>% by weight of a polyamide homopolymer,
<NUM>-<NUM>% by weight of maleic anhydride grafted polyethylene (MAgPE),
in combination with suitable additives,
wherein the suitable additives are selected from the group consisting of antistatics, UV protection-agents, compatibilisers, nucleation agents, colours.