High barrier polymer blend composition

Abstract

The invention relates to a polymer blend composition with high barrier property. A polymer blend composition comprising, based on the total weight of the polymer blend composition, 78 to 92% by weight of a homopolymer or copolymer of ethylene, 3 to 10% by weight of a polyamide homopolymer, 5 to 10% by weight of a maleic anhydride grafted polyethylene (MAgPE), and 0 to 2% by weight of an antistatic compound in combination with suitable additives.

Description

[0001] This application is a divisional application of an application filed on July 27, 2017, with application number 201710625605.3 and invention name “High Barrier Polymer Blend Composition”. Technical Field

[0002] The present invention relates to the field of polymer blend compositions and plastic containers made therefrom for the transportation of hazardous materials, and more particularly to high impact resistant containers with improved barrier properties.

[0003] The present invention further relates to a multilayer container comprising at least one layer made of the polymer blend composition, and a method for making the same. Background Art

[0004] Plastic containers used for the transport of hazardous materials need to display three main technical features to be considered suitable for the purpose:

[0005] - Structural strength to prevent ambient dispersion of the contents of the plastic container;

[0006] - Chemical resistance, so as not to be chemically damaged by the stored goods;

[0007] - Barrier properties to preserve the physico-chemical characteristics of the stored substances.

[0008] High-density polyethylene (HDPE), one of the most common polymers used in the manufacture of hazardous material containers, offers good mechanical properties but does not always provide the required barrier properties.

[0009] For hazardous substances that do have a flash point below 60°C, the barrier properties imparted by HDPE are generally insufficient and other materials need to be combined with the polyolefin to make an effective plastic container.

[0010] Currently, several technologies are known in the state of the art for providing high barrier HDPE containers for the collection of hazardous materials.

[0011] In EP 1748888 in-situ multilayer coextrusion blow moulding is described to provide a two-layer container comprising an outer layer and an inner layer.

[0012] The inner layer comprises a polyamide homopolymer and a maleic anhydride grafted polyethylene (MAgPE) coupling agent, while the outer layer comprises HDPE, a maleic anhydride grafted polyethylene coupling agent, and regrind material obtained from the residues of the outer and inner layers.

[0013] EP 1752492 discloses a thermoplastic resin composition and a thermoplastic resin product thereof, comprising a modified polyolefin, a barrier resin and a polyolefin, wherein, when the melt viscosity is measured at a shear rate of 100 Hz and at a temperature in the range of MP+2°C-MP+10°C (MP is the melting point of the barrier resin), the barrier resin and the polyolefin have a specific melt viscosity ratio in the range of 0.7 to 2.5.

[0014] EP 1752492 further describes a thermoplastic resin article comprising a layer made from the above thermoplastic resin composition.

[0015] There is a need to find technology suitable for manufacturing large-volume plastic containers for the transportation of hazardous materials that provide high barrier properties as well as high impact and chemical resistance. Summary of the invention

[0016] An object of the present invention is to provide a polymer blend composition suitable for the manufacture of large-capacity multi-layer containers that exhibit excellent barrier properties, chemical resistance, and impact resistance when compared to prior art containers.

[0017] A further object of the present invention is to provide a simple and economical method for the manufacture of plastic containers which is easily applicable to commercial materials and to effective blow molding machines without requiring costly modifications of the manufacturing equipment.

[0018] Still another object of the present invention is to provide a multi-layer container including a layer made of the polymer blend composition, which is economical, effective and easy to manufacture.

[0019] The manufacture of multilayer HDPE containers with implementable barrier properties is not new to the state of the art, but it has never been accomplished as simply as the method proposed in the present invention. DETAILED DESCRIPTION

[0020] Multi-layer container

[0021] The object of the present invention is a polymer blend composition comprising 78-92 wt.% of a homopolymer or copolymer of ethylene, 3-10 wt.% of a polyamide homopolymer, 5-10 wt.% of a maleic anhydride grafted polyethylene (MAgPE) and 0-2 wt.% of an antistatic compound in combination with suitable additives, based on the total weight of the polymer blend composition.

[0022] The homopolymer or copolymer of ethylene is preferably high density polyethylene.

[0023] The high density polyethylene for the purpose of the present invention has a range preferably between 0.945 and 0.955 g / cm 3 The density between.

[0024] Even more preferably, the high density polyethylene is selected from the group consisting of high density polyethylene homopolymer, high density ethylene / hexene copolymer or a mixture thereof.

[0025] Even more preferably, suitable high density polyethylene polymers are characterized by:

[0026] - Melt flow index in the range of 2-12 g / 10 min at 190°C / 21.6 kg,

[0027] - Yield strength in the range of 23-28 MPa at 23°C when stretched at 50 mm / min (ISO 527-1-2),

[0028] - Elongation at break in the range of 500-700% (ISO 527-2),

[0029] - Flexural modulus ranging between 850-1300 MPa,

[0030] - Environmental stress cracking (ASTM D1693) greater than 500 hours, preferably between 1000 and 2000 hours.

[0031] Suitable high-density polyethylenes that can be used within the scope of the present invention are available under the trade names Lupolen 4261AGUV 60005 (Basell Polyolefines), HM4560UA (Ineos Polyolefins), Polyethylene HDPE 49080UV (Total petrochemicals) those available in the market.

[0032] The polyamide homopolymer used in the polymer blend composition of the present invention is preferably polyamide 6.

[0033] In the context of the present invention, suitable polyamide 6 is more preferably characterized by:

[0034] -Range from 1.12 to 1.16 g / cm 3 The density between

[0035] -At 23°C, the range is 5 to 7 KJ / m 2 The Charpy notched impact strength between

[0036] - At 275°C / 21.6kg, range 43 to 47cm 3 / 10min between the melt volume flow rate,

[0037] - a melting point ranging between 220 and 224°C,

[0038] - Moisture content ranging between 0.03% and 0.1%.

[0039] A suitable polyamide 6 polymer within the scope of the present invention is, for example, the one available on the market under the trade name Grilon F50nat 6368 (a unit of EMS-GRIVORY | EMS-CHEMIE AG).

[0040] The polymer blend composition of the present invention further comprises maleic anhydride grafted polyethylene (MAgPE), which is a modified polyethylene functionalized with the anhydride of the unsaturated carboxylic acid maleic acid.

[0041] In a preferred embodiment, the MAgPE suitable for the polymer blend composition of the present invention has a range of 0.958-0.962 g / cm 3 A density between 500 and 500 , a melt flow rate at 190°C / 2.16 kg ranging from 1 to 3 g / 10 min, a melting point ranging from 130 to 137°C, and a maleic anhydride grafting rate ranging from 0.9 to 1.2 wt% based on the total weight of the MAgPE.

[0042] For the purposes of the present invention, suitable MAgPE is available under the trade name DuPont TM E MB100D (Dupont Packaging & Industrial Polymer) is one available in the market.

[0043] The polymer blend composition according to the present invention further comprises an antistatic compound.

[0044] As used in the context of the present invention, an antistatic compound is defined as having a 5 Ω <R0<10 12 Ω between the resistance R0 of the material.

[0045] Suitable antistatic agents for the purposes of the present invention are most preferably selected from the group consisting of polyamide-polyether block amide mixtures.

[0046] In a general sense, polyether block amides (polyetheresteramides) or PEBAs are block copolymers obtained by polycondensation of carboxylic acid polyamides (PA6, PA11, PA12) with polyoxyalkylene glycols (polytetramethylene glycol PTMG; PEG).

[0047] PEBA is a high-performance thermoplastic elastomer that exhibits low density among TPEs, excellent mechanical and dynamic properties (flexibility, impact resistance, energy recovery, fatigue resistance) and the ability to maintain these properties at low temperatures (below -40°C).

[0048] Polyamide / polyether block amide blends are polymer systems comprising polyamide and the thermoplastic PEBA elastomers mentioned.

[0049] Among the preferred polyamide / polyether block amide mixtures, the one most preferred for the purposes of the present invention is that sold under the trade name A polymer system known as P18, manufactured by Ciba Specialty Chemicals and providing a permanent antistatic effect.

[0050] In another preferred embodiment, the polymer blend composition disclosed in the present application may eventually contain other additives, such as pigments (colour), UV protectants (anti-UV agents), compatibilizers, nucleating agents.

[0051] The aforementioned polymer blend compositions, in view of the specific selection of components and concentrations, allow for the manufacture of plastic containers for the transportation of hazardous materials that exhibit superior barrier properties, chemical resistance, and impact resistance when compared to state-of-the-art plastic containers.

[0052] In the context of the present invention, hazardous substances are understood to mean any substance belonging to the categories 3-6, 8-9 provided by the "Recommendations on the Transport of Dangerous Goods", which correspond to flammable liquids; flammable solids, substances liable to spontaneous combustion, substances which emit flammable gases in contact with water; oxidizing substances and organic peroxides; toxic substances and infectious substances; corrosive substances; miscellaneous dangerous substances and articles including environmentally hazardous substances ( http: / / www.unece.org / fileadmin / DAM / trans / danger / publi / unrec

[0053] / rev19 / Rev19e_Vol_I.pdf ).

[0054] The polymer blend composition of the present invention is used to manufacture the inner container of an intermediate bulk container (IBC) for the storage and collection of liquid or gel hazardous materials.

[0055] The polymer blend compositions of the present invention are particularly advantageous for the manufacture of plastic containers suitable for the storage and collection of, for example, petroleum products, aromatic solvents, aliphatic solvents, ketones, kerosene, alcohols, and commercial products dissolved in such solvents, such as paints, pesticides and herbicides.

[0056] The present invention also relates to a multilayer container comprising a barrier layer made from the polymer blend composition according to the invention and at least one further layer comprising HDPE.

[0057] Advantageously, the barrier layer according to the present invention provides good barrier properties for hydrocarbon materials, even more preferably for the following test materials: trichloroethylene (flash point (FP) 89.6°C), cyclohexanone (FP 44°C), hexane (FP-26°C), propanol (FP 22°C) and xylene (FP 30°C).

[0058] Even more preferably, the at least one further layer comprises 70-100 wt.% HDPE, 0-20 wt.% antistatic compounds, 0-10 wt.% additives, preferably chosen among compatibilizers, pigments and anti-UV agents.

[0059] In a first preferred embodiment, the multilayer container according to the present invention consists of three layers: a barrier layer made of the polymer blend composition according to the present invention, a first layer made of HDPE, a second layer made of HDPE.

[0060] The three layers include an inner layer, an outer layer, and an intermediate layer disposed between the inner layer and the outer layer. The inner layer is designed to contact the hazardous substances stored in the multi-layer container.

[0061] In the first preferred embodiment, the first layer is an inner layer, the second layer is an outer layer, and the barrier layer is an intermediate layer disposed between the first layer and the second layer.

[0062] In a second preferred embodiment, the multilayer container according to the present invention consists of three layers: a barrier layer made of the polymer blend composition according to the present invention; a first layer made of HDPE; a second layer, the second layer comprising 70-90 wt. % HDPE, 5-20 wt. % antistatic compound, preferably P18, and 1-10 wt% of additives, preferably 4 wt% of a compatibilizer, 1 wt% of an anti-UV agent and optionally a color masterbatch.

[0063] Even more preferably, the compatibilizer is Lotader AX 8900.

[0064] In the second preferred embodiment, the first layer is an inner layer, the second layer is an outer layer and the barrier layer is an intermediate layer disposed between the first layer and the second layer.

[0065] Advantageously, the presence of MAgPE in the polymer blend composition according to the present invention provides good adhesion between the three layers without the need to introduce an additional adhesive layer.

[0066] Even more preferably, the barrier layer of the multilayer container comprises 0-40 wt. % of regrind material from the barrier layer and from the at least one further layer.

[0067] More specifically, according to a preferred embodiment, the barrier layer comprises 0-40 wt. % of regrind material from the barrier layer, the first layer and the second layer.

[0068] Whether present or not, the antistatic compound comprised in the at least one further layer is preferably the same antistatic compound comprised in the polymer blend composition according to the present invention.

[0069] The multilayer container according to the present invention preferably has a capacity ranging from 800L to 1200L, and from the perspective of the aforementioned capacity, has a total weight ranging from 14kg to 21kg, wherein the outer layer has a weight preferably ranging from 2kg to 3kg, and in particular, the inner layer and the middle layer have a weight preferably ranging from 6kg to 9kg.

[0070] Another object of the present invention is a method for manufacturing a multilayer container, which method comprises the following steps:

[0071] i. dry blended ethylene homopolymers or copolymers, polyamides and maleic anhydride grafted polyethylene;

[0072] ii. melting the dry blended polymer material according to step i in an extruder;

[0073] iii. coextruding the dry blended polymer material with at least one additional layer comprising HDPE to form a multilayer parison;

[0074] iv. Blowing the multilayer parison in a mold to obtain a multilayer container;

[0075] v. Cutting the residual material of the multi-layer parison extending beyond the mold;

[0076] vi. Recycling of said residual materials to subsequent production cycles.

[0077] Preferably, residual material obtained from each production cycle of the aforementioned process is added to stage i and dry-blended with the other polymers.

[0078] Embodiments of multi-layer containers

[0079] For illustrative but not limiting purposes, we provide here two examples of polymer blend compositions for the manufacture of multilayer containers according to the present invention.

[0080] Embodiment 1: The multi-layer container according to the present invention is characterized by a total weight of 17.5 kg, a capacity of 1000 L and a thickness of 1.5 mm to 2.5 mm.

[0081]

[0082] Embodiment 2: The multi-layer container according to the present invention is characterized by a total weight of 17.5 kg, a capacity of 1000 L and a thickness of 1.5 mm to 2.5 mm.

[0083]

[0084] Single layer container

[0085] Further polymer blend compositions, single-layer containers obtained therefrom and methods for making the same, which do not form part of the present invention, are described hereinafter according to the following items:

[0086] 1. A polymer blend composition comprising 68-87 wt% of a homopolymer or copolymer of ethylene, 5-15 wt% of a polyamide homopolymer, 8-17 wt% of a maleic anhydride grafted polyethylene (MAgPE) in combination with suitable additives.

[0087] 2. The polymer blend composition according to claim 1, wherein the homopolymer or copolymer of ethylene has a molecular weight in the range of 0.945-0.955 g / cm 3 The density is between that of high-density polyethylene.

[0088] 3. The polymer blend composition according to item 2, wherein the high-density polyethylene is selected from the group consisting of high-density polyethylene homopolymer, high-density polyethylene / hexene copolymer and mixtures thereof.

[0089] 4. The polymer blend composition according to any one of items 1 to 3, wherein the polyamide homopolymer is polyamide 6.

[0090] 5. The polymer blend composition according to any one of items 1 to 4, wherein the suitable additive is selected from the group consisting of an antistatic agent, a UV protectant, a compatibilizer, a nucleating agent, and a pigment.

[0091] 6. A single-layer container consisting of one layer made of the polymer blend composition according to any one of items 1 to 4.

[0092] 7. A single-layer container according to item 5, wherein the single-layer container contains 0-40% of regrind material from the one layer.

[0093] There is described a polymer blend composition which is not part of the present invention and comprises 68-87 wt% of a homopolymer or copolymer of ethylene, 5-15 wt% of a polyamide homopolymer, 8-17 wt% of a maleic anhydride grafted polyethylene (MAgPE) in combination with suitable additives.

[0094] The homopolymer or copolymer of ethylene is preferably high-density polyethylene. The high-density polyethylene has a range of preferably 0.945-0.955 g / cm 3 The density between.

[0095] Even more preferably, the high density polyethylene is selected from the group consisting of high density polyethylene homopolymer, high density ethylene / hexene copolymer or a mixture thereof.

[0096] Even more preferably, suitable high density polyethylene hydrocarbon polymers are characterized by:

[0097] - Melt flow index in the range of 2-12 g / 10 min at 190°C / 21.6 kg,

[0098] - Yield strength in the range of 23-28 MPa at 23°C when stretched at 50 mm / min (ISO 527-1-2),

[0099] - Elongation at break in the range of 500-700% (ISO 527-2),

[0100] - Flexural modulus ranging between 850-1300 MPa,

[0101] - Environmental stress cracking greater than 500 hours, preferably between 1000 and 2000 hours.

[0102] Suitable homopolymers or copolymers of ethylene that can be used in the polymer blends are sold under the trade names Lupolen 5261Z (Basell Polyolefines), HXM 50100 (Chevron Philips Chemical Company), HDPE 56020S (Total refining&Chemicals), HM5420XPH (INEOS Olefines and Polymers Europe), Polyethylene HDPE 49080UV (Total petrochemicals) are those available in the market.

[0103] The polyamide homopolymer used in the aforementioned polymer blend is preferably polyamide 6.

[0104] Suitable polyamide 6 for the polymer blend composition is more preferably characterized by:

[0105] -Range from 1.12 to 1.16 g / cm 3 The density between

[0106] -At 23°C, the range is 5 to 7 KJ / m 2 The Charpy notched impact strength between

[0107] - At 275°C / 21.6kg, range 43 to 47cm 3 / 10min between the melt volume flow rate,

[0108] - a melting point ranging between 220 and 224°C,

[0109] - Moisture content ranging between 0.03% and 0.1%.

[0110] More preferably, a suitable polyamide 6 is for example the one commercially available under the trade name Grilon F 50nat 6368 (a unit of EMS-GRIVORY | EMS-CHEMIE AG).

[0111] The polymer blend composition further comprises maleic anhydride grafted polyethylene (MAgPE), which is a modified polyethylene functionalized with the anhydride of the unsaturated carboxylic acid maleic acid.

[0112] In a preferred embodiment, the MAgPE suitable for the polymer blend composition of the present invention has a range of 0.958-0.962 g / cm 3 A density between 500 and 500 , a melt flow rate at 190°C / 2.16 kg ranging from 1 to 3 g / 10 min, a melting point ranging from 130 to 137°C, and a maleic anhydride grafting rate ranging from 0.9 to 1.2 wt% based on the total weight of the MAgPE.

[0113] Suitable MAgPE is available, for example, under the trade name DuPont TM One available in the market under E MB100D (Dupont Packaging & Industrial Polymer).

[0114] In another preferred embodiment, the polymer blend composition may eventually contain other additives such as antistatic agents, pigments, UV protectants (anti-UV agents), compatibilizers, nucleating agents.

[0115] The aforementioned polymer blend compositions, in view of the specific selection of components and concentrations, allow for the manufacture of plastic containers for the transportation of hazardous materials that exhibit superior barrier properties, chemical resistance, and impact resistance when compared to state-of-the-art plastic containers.

[0116] The polymer blend composition is used to manufacture a single-layer container for storage and collection of liquid or gel hazardous materials.

[0117] The polymer blend compositions are particularly advantageous for the manufacture of plastic containers suitable for the storage and collection of, for example, petroleum products, aromatic solvents, aliphatic solvents, ketones, kerosene, alcohols, and commercial products dissolved in such solvents, such as paints, pesticides and herbicides.

[0118] Advantageously, the barrier layer according to the present invention provides good barrier properties for hydrocarbon materials, even more preferably for the following test materials: trichloroethylene (flash point (FP) 89.6°C), cyclohexanone (FP 44°C), hexane (FP-26°C), propanol (FP 22°C) and xylene (FP 30°C).

[0119] Also disclosed below is a single-layer container not according to the present invention, which is composed of one layer made of the above-mentioned polymer blend composition.

[0120] The single-layer container preferably has a capacity ranging between 1 L and 30 L and, in relation to the above capacity, has a thickness ranging between 0.7 mm and 4.0 mm.

[0121] The single-layer container is preferably manufactured by a method comprising the following steps:

[0122] a. dry blending of ethylene homopolymers or copolymers, polyamides and maleic anhydride grafted polyethylene;

[0123] b. melting the dry blended polymer material according to step a in an extruder;

[0124] c. extruding the dry blended polymer material to form a single-layer parison;

[0125] d. Blowing the single-layer parison in a mold to obtain a single-layer container;

[0126] e. Cutting the residual material of the single-layer parison container extending beyond the mold;

[0127] f. Recycling of said residual materials to subsequent production cycles.

[0128] Preferably, the residual material obtained from each production cycle of the aforementioned process is added to stage a and dry-blended with the other polymers.

[0129] More specifically, according to a preferred embodiment, the single-layer container comprises 0-40 wt. % of regrind material from the one layer.

[0130] Embodiment of single layer container

[0131] For illustrative but not limiting purposes, we provide here two examples of polymer blend compositions for the manufacture of monolayer containers not according to the present invention.

[0132] Embodiment 1:A single-layer container not according to the invention is characterized by a total weight of 15.5 kg, a capacity of 1000 L and a thickness of 1.4-2.2 mm.

[0133]

[0134] Embodiment 2: A single-layer container not according to the invention is characterized by a total weight of 270 g, a capacity of 5 L and a thickness of 0.7-2.0 mm.

[0135]

Claims

1. A multi-layer container for transporting hazardous substances, characterized in that: It comprises a barrier layer made of a polymer blend composition, and at least one additional layer, the at least one additional layer comprising HDPE, based on the total weight of the polymer blend composition, the polymer blend composition is composed of 78-84 wt% of ethylene homopolymer or copolymer, 3-10 wt% of polyamide homopolymer, 5-10 wt% of maleic anhydride grafted polyethylene MAgPE, greater than 0 wt% and less than or equal to 2 wt% of antistatic compounds and 0-40 wt% of regrind materials from the barrier layer and from the at least one additional layer, the additives are selected from the group consisting of pigments, compatibilizers, nucleating agents and UV protectants, the UV protectant is composed of BF UV 1610, the antistatic compound comprises P18, the multilayer container comprises only high-density polyethylene as the homopolymer or copolymer of ethylene.

2. The multi-layer container according to claim 1, wherein The homopolymer or copolymer of ethylene has a range of 0.945-0.955 g / cm 3 The density is between that of high-density polyethylene.

3. The multi-layer container according to claim 2, wherein: The high-density polyethylene is selected from the group consisting of high-density polyethylene homopolymer, high-density polyethylene / hexene copolymer and mixtures thereof.

4. The multi-layer container according to any one of claims 1 to 3, wherein: The polyamide homopolymer is polyamide 6.

5. The multi-layer container according to any one of claims 1 to 3, wherein: The antistatic compound has a 5 Ω <R0<10 12 The resistance R0 between Ω.

6. The multi-layer container according to claim 5, wherein: The antistatic compound is selected from the group consisting of polyamide / polyether block amide mixtures.

7. The multi-layer container according to any one of claims 1 to 3, wherein: The at least one further layer comprises 70-100 wt. % HDPE, 0-20 wt. % antistatic compound and 0-10 wt. % additives.

8. The multi-layer container according to any one of claims 1 to 3, wherein: The at least one additional layer comprises a first layer and a second layer, and the multi-layer container is composed of three layers: - an inner layer, corresponding to said first layer and made of high-density polyethylene, - an intermediate layer, said intermediate layer corresponding to said barrier layer, - an outer layer corresponding to the second layer and made of high-density polyethylene.

9. The multi-layer container according to any one of claims 1 to 3, wherein: The at least one additional layer comprises a first layer and a second layer, and the multi-layer container is composed of three layers: - an inner layer corresponding to said first layer made of high-density polyethylene, - an intermediate layer, said intermediate layer corresponding to said barrier layer, - an outer layer, corresponding to the second layer, comprising 70-90% by weight of HDPE, 5-20% by weight of antistatic compounds and 1-10% by weight of additives.

10. Use of the multi-layer container according to any one of claims 1 to 9 for transporting hazardous substances.

Images