WO2023242415A1 - Food container comprising a reinforced polyamide composition exhibiting a slow release of aluminium - Google Patents

Food container comprising a reinforced polyamide composition exhibiting a slow release of aluminium Download PDF

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Publication number
WO2023242415A1
WO2023242415A1 PCT/EP2023/066294 EP2023066294W WO2023242415A1 WO 2023242415 A1 WO2023242415 A1 WO 2023242415A1 EP 2023066294 W EP2023066294 W EP 2023066294W WO 2023242415 A1 WO2023242415 A1 WO 2023242415A1
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WO
WIPO (PCT)
Prior art keywords
composition
food container
food
group
polyamide
Prior art date
Application number
PCT/EP2023/066294
Other languages
French (fr)
Inventor
Chinomso NWOSU
Keshav S. Gautam
Original Assignee
Solvay Specialty Polymers Usa, Llc
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Publication of WO2023242415A1 publication Critical patent/WO2023242415A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L77/00—Compositions of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Compositions of derivatives of such polymers
    • C08L77/06—Polyamides derived from polyamines and polycarboxylic acids
    • A—HUMAN NECESSITIES
    • A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
    • A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
    • A47J36/00—Parts, details or accessories of cooking-vessels
    • A47J36/02—Selection of specific materials, e.g. heavy bottoms with copper inlay or with insulating inlay
    • A47J36/025—Vessels with non-stick features, e.g. coatings
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/02—Elements
    • C08K3/04—Carbon
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K3/00—Use of inorganic substances as compounding ingredients
    • C08K3/34—Silicon-containing compounds
    • C08K3/346—Clay
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
    • C08K7/00—Use of ingredients characterised by shape
    • C08K7/02—Fibres or whiskers
    • C08K7/04—Fibres or whiskers inorganic
    • C08K7/14—Glass
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G2390/00—Containers
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G69/00—Macromolecular compounds obtained by reactions forming a carboxylic amide link in the main chain of the macromolecule
    • C08G69/02—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids
    • C08G69/26—Polyamides derived from amino-carboxylic acids or from polyamines and polycarboxylic acids derived from polyamines and polycarboxylic acids

Definitions

  • the present invention relates to a food container comprising a reinforced polyamide composition (C) comprising a polyamide (PA) exhibiting a slow release of aluminium.
  • Composition (C) comprises polyamide (PA) and from 20.0 to 80.0% by weight (wt%) of a glass fiber (GF), dispersed in the composition, relative to the total weight of the composition, wherein the glass fiber (GF) comprises alumina (AI2O3) in an amount of from 9.0 to 25.0 wt%, relative to the total weight of the glass fiber. It also relates to the use of the composition (C).
  • Materials and articles intended to come into direct or indirect contact with food are used at any point in the food chain, i.e. from the start to the end of the food chain.
  • Foods are in contact with a variety of materials starting at the farm, during factory processing and packaging eventually to be used in the kitchen for preparing and cooking foods.
  • the applications are diverse as are the materials themselves, which include plastics, paper, rubber, ceramics, metal, glass, wood and cork.
  • all of these materials must be safe in terms of release of chemicals and/or metals into foods that are of safety concern, i.e. exceeding the levels that have the potential to cause harm to human health or cause contamination to food. Legislations impose a limited release of some contaminants into the food.
  • US 2015/274935 discloses a polyamide moulding composition in particular for use in the drinking water sector, made of the following constituents: from 25 to 74.9% by weight of at least one semicrystalline, semi-aromatic nylon-6, T/6, 1, composed of: (al) from 65 to 82 mol% of terephthalic acid, based on the entirety of the di carboxylic acids used; (a2) from 18 to 35 mol% of isophthalic acid, based on the entirety of the di carboxylic acids used; (a3) 1 ,6-diaminohexane; (a4) at least one monobasic carboxylic acid.
  • glass fibers usually contain alumina (AI2O3) as one of essential elements.
  • Aluminium (Al) an element present in alumina, that is under control as one of heavy metals when in use in food applications, may be released/leached to foods at particular conditions.
  • Europe has a harmonized legal framework [Regulation (EC) no. 1935/2004] “Basic requirements for materials and articles intended to come into contact with foods ” that requires all food contact materials and articles manufactured, imported and sold in the EU to comply with.
  • Commission Regulation EU No. 10/2011 stipulates in its Annex II that plastic materials shall not release Al exceeding 1.0 mg/kg of specific migration limit (SML). Also, in the USA, prior approval by the authorities is required in using a new material in food applications.
  • the invention relates to a food container as disclosed in claims 1-15.
  • PA polyamide
  • the component is the food container itself, notably when the food container is tiny and/or not complex.
  • the invention also relates to a food container made of or comprising the composition (C) as disclosed herein.
  • the food container may more particularly be a cooking utensil.
  • a cooking utensil is a vessel in which food is prepared and/or stored.
  • the component of the cooking utensil that may come into contact with the food may for instance be the walls of the cooking utensil.
  • the part that may come into contact with the food may be a means for kneading and/or mixing food,
  • the cooking utensil may be heated thanks to electric heating means close to the vessel. These electric heating means are used to heat the food inside the vessel notably for cooking and/or keeping warm the food.
  • the invention also relates to an appliance comprising the cooking utensil and electric means used to heat the food inside the vessel notably for cooking and/or keeping warm the food.
  • Composition (C) comprises or consists of:
  • Conditions of the test are the following: the content of aluminium leached out from composition (C) into an aqueous solution is measured after putting into contact the composition (C) with an aqueous solution of acetic acid (30 g of acetic acid with distilled water to a volume of IL); conditions: 24 hours; 100°C .
  • the test shall be carried out three times on a single sample using fresh solution on each occasion. Compliance with the test shall be checked on the basis of the level of the migration found in the third test.
  • the migration of Al is preferably 0.5 mg/kg or less, preferably 0.2 mg/kg or less, as measured according to the conditions disclosed herein.
  • This diamine is more particularly selected in the group of (i) the amines of formula (V) where R3 is selected from the group consisting of C4-C12 alkylene groups; a /u.s(aminomethyl) cyclohexane selected from the group consisting of 1,3- /v.s(aminomethyl (cyclohexane (“1,3-BAC”), 1 ,4-/?/.s(aminomethyl (cyclohexane (“1,4-BAC”) and combination thereof.
  • R3 is selected from the group consisting of C4-C12 alkylene groups
  • a /u.s(aminomethyl) cyclohexane selected from the group consisting of 1,3- /v.s(aminomethyl (cyclohexane (“1,3-BAC”), 1 ,4-/?/.s(aminomethyl (cyclohexane (“1,4-BAC”) and combination thereof.
  • R3 may more particularly a radical derived from an aliphatic diamine selected from the group consisting of hexamethylenediamine, 1,9-nonanediamine, 1 , 10-diaminodecane, 1,12- diaminododecane, 2-methyl-octanediamine, 2-methyl-l,5-pentanediamine, 1 ,4-diaminobutane.
  • the proportion of the GF(s) in composition (C) is between 20.0 and 80.0 wt%. This proportion may be between 20.0 and 50.0 wt%.
  • the proportion of the polyamide(s) (PA) in compostion (C) is preferably at least 50.0 wt%, preferably at least 55.0 wt%.
  • Suitable polyamides are commercially available under the trade name AMODEL® from Solvay Specialty Polymers USA, LLC.
  • Polyamide (PA) has a melting point (Tm) of at least 275°C, preferably at least 290°C, more preferably at least 305°C, preferably at least 310°C and/or of at most 350°C, preferably at most 340°C, more preferably at most 330°C, as measured according to ASTM D3418.
  • Tm melting point
  • Polyamide (PA) has a glass transition temperature (Tg), as measured according to ASTM D3418, of at least 90°C, more preferably at least 100°C, more preferably at least 120°C, and/or of at most 220°C, preferably at most 200°C, more preferably at most 180°C.
  • Tg glass transition temperature
  • Polyamide (PA) is semi-crystalline.
  • Polyamide (PA) has a heat of fusion (Hm) of at least 10.0 J/g, preferably at least 20.0 J/g, preferably at least 30.0 J/g and/or of at most 100.0 J/g, preferably at most 90.0 J/g, more preferably at most 80.0 J/g, as measured according to ASTM D3418.
  • Hm heat of fusion
  • glass transition temperature T g
  • T m melting temperature
  • Polyamide (PA) is formed by polycondensation of a monomer mixture as disclosed herein.
  • the polycondensation is performed the monomer mixture in presence of less than 60 wt% of water, preferentially less than 50 wt%, up to a temperature of at least T m + 10°C, T m being the melting temperature of the polyamide (PA) wherein wt% is relative to the total weight of the reaction mixture.
  • T m being the melting temperature of the polyamide (PA) wherein wt% is relative to the total weight of the reaction mixture.
  • the temperature at which the polycondensation is performed is generally at least 200°C.
  • the monomer mixture is such that the molar ratio [-COOH]/[-NH2] is from 0.9 to 1.1, preferably from 0.95 to 1.07, more preferably 1.00 to 1.05, where [-COOH] and [-NH2] are the number of moles of -NH2 and -COOH groups from the monomers in the monomer mixture.
  • the reaction mixture preferably comprises a catalyst.
  • the catalyst of polycondensation may be selected in the group consisting of phosphorous acid, ortho-phosphoric acid, meta-phosphoric acid, alkali-metal hypophosphite such as sodium hypophosphite and phenylphosphinic acid.
  • a convenient catalyst used is sodium hypophosphite.
  • the reaction mixture generally also further comprise at least one end-capping agent as disclosed above. The end-capping agent may notably be used to control the molecular weight.
  • the end -groups of the polyamide (PA) are selected in the group of-NH2, -COOH and amide end- groups. Indeed, the end-groups in the polyamide (PA) may be -NH2 or -COOH. Yet, when the polycondensation involves the addition of an end-capping agent, these end-groups may be converted, partially or totally, into amide end-groups.
  • R is more particularly a linear or branched C2-C18 alkyl group or a C5-C10 cycloalkyl group.
  • R' is more particularly a linear or branched C2-C18 alkyl group.
  • the monocarboxylic acid (end-capping agent) may advantageously be selected in the group consisting of benzoic acid; cyclohexanoic acid; R-COOH where R is a linear or branched C2-C18 alkyl group and combination of two or more of these acids. R is the radical derived from the acid of formula R-COOH.
  • the monocarboxylic acid (end-capping agent) may more particularly be selected in the group consisting of acetic acid, propanoic acid, butyric acid, valeric acid, caproic acid, lauric acid, stearic acid, 2-ethylhexanoic acid, cyclohexanoic acid, benzoic acid and combination of two or more of these acids.
  • the monocarboxylic acid (end-capping agent) is more particularly of formula CH3-(CH2) n -COOH where n is an integer between 0 and 16.
  • Composition (C) may be prepared by melt-blending the polyamide (PA) and the other components of the composition (C). Melt-blending is usually performed by using a melt mixer selected in the group consisting of an extruder (e.g. a single screw extruder or a twin screw extruder), a single screw, a twin screw kneader and a Banbury mixer. Melt-blending is conveniently performed with an extruder (e.g. a single screw extruder or a twin screw extruder).
  • Composition (C) comprises at least one polyamide (PA). It may comprise only one polyamide (PA) or more than one polyamides (PA). According to a preferred embodiment, the composition (C) does not comprise any polyamide other than polyamide(s) (PA).
  • Composition comprises at least one glass fiber (GF).
  • Glass fibers are silica-based glass compounds that contain several metal oxides which can be tailored to create different types of glass.
  • the main oxide is silica (SiCh) in the form of silica sand; the other oxides such as calcium oxide (CaO), sodium oxide (Na20) and alumina (AI2O3) are incorporated to adjust the properties of interest, e.g. to lower the melting temperature and to impede crystallization.
  • the glass fibers may be endless glass fibers or chopped glass fibers.
  • the glass fiber comprises alumina (AI2O3) in an amount of from 9.0 to 25.0 wt%, relative to the total weight of the glass fiber (GF). This proportion is preferably between 12.0 and 20.0 wt%, preferably between 12.0 and 17.0 wt%.
  • the glass fibers have an average length of from 3 mm to 50 mm. In some such embodiments, the glass fibers have an average length of from 3 mm to 10 mm, from 3 mm to 8 mm, from 3 mm to 6 mm, or from 3 mm to 5 mm. In alternative embodiments, the glass fibers have an average length of from 10 mm to 50 mm, from 10 mm to 45 mm, from 10 mm to 35 mm, from 10 mm to 30 mm, from 10 mm to 25 mm or from 15 mm to 25 mm.
  • the glass fibers have generally an equivalent diameter of from 5 to 20 pm, preferably of from 5 to 15 pm, more preferably of from 5 to 10 pm.
  • the flat glass fiber has an aspect ratio, defined as the average ratio between the length and the largest of the width and thickness, of at least 2, preferably at least 2.2, more preferably at least 2.4, still more preferably at least 3.
  • the aspect ratio is defined as a ratio of the longest diameter in the cross-section of the glass fiber to the shortest diameter in the same crosssection.
  • the flat glass fiber has an aspect ratio of at most 8, preferably at most 6, more preferably of at most 4.
  • the flat glass fiber has an aspect ratio of from 2 to 6, and preferably, from 2.2 to 4.
  • the additive(s) (A) is/are comprised in an amount of from 0.1 wt% to 5.0 wt%, preferably from 0.2 wt% to 3.0 wt%, more preferably from 0.4 wt% to 2.0 wt%, most preferably 0.5 wt% to 1.0 wt%, based upon the total weight of composition (C).
  • the additive (A) is generally selected from the group consisting of impact modifiers, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants (e.g. linear low density polyethylene (LLDPE), calcium stearate, magnesium stearate or sodium montanate), thermal stabilizers, light stabilizers, antioxidants, nucleating agents, polymer processing aids, antiblocking agents, slip agents, antifogging agents, chemical blowing agents, nucleating agents, and any combination thereof.
  • the additive (A) is selected from the group consisting of impact modifiers, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, and any combination thereof.
  • Composition (C) preferably comprises at least one impact modifier as an additive.
  • the impact modifier useful herein is not particularly limited, so long as it imparts useful properties to the polyamide, such as sufficient tensile elongation at yield and break.
  • Useful impact modifiers include polyolefins, preferably functionalized polyolefins, and especially elastomers such as styrene- ethylene-butylene-styrene (SEBS) and ethylene-propylene-diene monomer (EPDM).
  • SEBS styrene- ethylene-butylene-styrene
  • EPDM ethylene-propylene-diene monomer
  • the impact modifier is selected from the group consisting of a maleic anhydride functionalized EPDM rubber, a maleic anhydride functionalized SEBS block copolymer, and mixtures thereof.
  • Still other impact modifiers useful herein include acrylic impact modifiers commercialized as Paraloid® impact modifiers by Rohm & Haas.
  • Suitable functional groups on the impact modifier include any chemical moieties that can react with end groups of the polyamide to provide enhanced adhesion to the high temperature matrix.
  • the composition (C) may comprise at least one filler which is different from glass fibers, as described above.
  • a large selection of fillers may be added to the composition according to the present invention, which can be selected from fibrous and particulate fillers.
  • GF2 OCV FC Advantex®, commercially available from Owens Corning GF3: NEG 3610 ECR, commercially available from Nippon Electric Glass GF4: CPIC CS HL (301), commercially available from Chongqing Polycomp International Corp.
  • LLDPE Linear low-density polyethylene
  • the content of Al (that is the elemental composition) in glass fibers was determined by Scanning Electron Microscopy (SEM)/ Energy Dispersive X-ray Spectroscopy (EDS) as 7.8 wt%, 8.2 wt%, 9.5 wt% and 10.5 wt%, corresponding to alumina (AI2O3) content of 14.7 wt%, 15.5 wt%, 17.9 wt% and 19.8 wt%, respectively.
  • SEM Scanning Electron Microscopy
  • EDS Energy Dispersive X-ray Spectroscopy
  • the elemental composition of surfaces of glass fibers (about 0.01 to 1.0 um in SEM) was performed by EDS. In this technique, the energy of X-ray signals generated by electron beam hitting the sample surface was measured. This was made under the assumption that the composition of glass fibers on the surface are equivalent to the composition in the bulk barring the presence of glass fiber sizing which is limited to few angstroms (A) on the surface.
  • M3 specific migration limit (SML); Ml > M2 > M3; and Ml, M2 and M3 should be less than SML, respectively, when SML is not detected.
  • SML is maximum permitted level of Al migrating from the final material/article into the food simulant.
  • SML of Al is 1.0 mg/kg under Commission Regulation (EU) No. 10/2011 (Annex II).

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Food Science & Technology (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

The present invention relates to a food container comprising at least one component that may come into contact with the food and which is made of or comprises a composition (C), wherein the composition (C) comprises or consists of: - at least one polyamide (PA) exhibiting a Tg of at least 90.0 °C as measured according to ASTM D3418; - from 20.0 to 80.0 wt% of glass fibers (GF) comprising alumina (A12O3) in an amount of from 9.0 to 25.0 wt% relative to the total weight of the glass fibers (GF), the glass fiber being dispersed in the composition (C), this proportion being relative to the total weight of the composition (C); - optionally at least one filler (F) different from the glass fiber (GF); optionally at least one additive (A) different from the glass fiber (GF) and the filler (F), notably selected in the group consisting of: impact modifiers, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, and any combination thereof.

Description

FOOD CONTAINER COMPRISING A REINFORCED POLYAMIDE COMPOSITION EXHIBITING A SLOW RELEASE OF ALUMINIUM
This application claims priority of European patent application No. 22179473.8 filed on 16 June 2022, the content of which being entirely incorporated herein by reference for all purposes. In case of any incoherency between the two applications that would affect the clarity of a term or expression, it should be made reference to the present application only.
[TECHNICAL FIELD]
The present invention relates to a food container comprising a reinforced polyamide composition (C) comprising a polyamide (PA) exhibiting a slow release of aluminium. Composition (C) comprises polyamide (PA) and from 20.0 to 80.0% by weight (wt%) of a glass fiber (GF), dispersed in the composition, relative to the total weight of the composition, wherein the glass fiber (GF) comprises alumina (AI2O3) in an amount of from 9.0 to 25.0 wt%, relative to the total weight of the glass fiber. It also relates to the the use of the composition (C).
[BACKGROUND]
Materials and articles intended to come into direct or indirect contact with food are used at any point in the food chain, i.e. from the start to the end of the food chain. Foods are in contact with a variety of materials starting at the farm, during factory processing and packaging eventually to be used in the kitchen for preparing and cooking foods. The applications are diverse as are the materials themselves, which include plastics, paper, rubber, ceramics, metal, glass, wood and cork. In particular, all of these materials must be safe in terms of release of chemicals and/or metals into foods that are of safety concern, i.e. exceeding the levels that have the potential to cause harm to human health or cause contamination to food. Legislations impose a limited release of some contaminants into the food. Materials used in drinking-water systems, which are subject to German legislation relating to materials having direct or indirect contact with the human body, are required by DIN 1988 to be such that no impermissible impairment of drinking water in terms of its suitability for human consumption is caused. For instance, the Guideline for Hygienic Assessment of Organic Materials in Contact with Drinking Water (KTW Guideline, issued on 16 May 2007) describes inter aha a warm water test at (60±2°) C and a hot water test at (85±2°) C (migration test method corresponding to DIN EN 12873-1 : 2004 and -2: 2005) and establishes specific migration rates for "carbon release" in contact with drinking water. It is impermissible here to exceed the guideline value ofl 2.5 mg C/m2 at the 7th extraction.
Several patent applications discloses polyamide compositions. EP 2650331 discloses a polyamide composition containing 10-50 wt% of a partially crystalline polyamide and 5-30 wt% of an amorphous polyamide.
US 2015/274935 (DI) discloses a polyamide moulding composition in particular for use in the drinking water sector, made of the following constituents: from 25 to 74.9% by weight of at least one semicrystalline, semi-aromatic nylon-6, T/6, 1, composed of: (al) from 65 to 82 mol% of terephthalic acid, based on the entirety of the di carboxylic acids used; (a2) from 18 to 35 mol% of isophthalic acid, based on the entirety of the di carboxylic acids used; (a3) 1 ,6-diaminohexane; (a4) at least one monobasic carboxylic acid.
US 2016/0272788 (D2) discloses a thermoplastic moulding composition consisting of: (A) 20-63% by weight of a thermoplastic material consisting of polyamide (Al) or a mixture of polyamides, with the proviso that up to 40% thereof can be replaced by a thermoplastic material (A2) not based on polyamide; (B) 35-60% by weight of high-strength glass fibres (Bl_2) based on the ternary system silicon dioxide/aluminumoxide/magnesium oxide or on the quaternary system silicon dioxide/aluminum oxide/magnesium oxide/calcium oxide, and having the following composition 58-70% by weight of silicon dioxide (SiCh), 15-30% by weight of aluminium oxide (AI2O3), 5- 15% by weight of magnesium oxide (MgO), 0-10% by weight of calcium oxide (CaO) and 0-2% by weight of further different oxides.
JP 2018070830 (D3) relates to a polyamide composition and a molded article thereof (claims 1-7; [0001 ]). D3 discloses glass fibers having an elemental Al content of 8.0-12.5 wt% ([0052]; table 1).
These documents do not disclose a food container as claimed. [TECHNICAL PROBLEM TO BE SOLVED]
Nowadays, many food containers such as cooking utensils are made of or comprise a part in plastic which may come repeatedly in contact with the food contained therein. The food container must be mechanically resistant and since the food contained therein may be hot, it must also be thermally resistant. Glass fibers can contribute to the mechanical resistance of the plastic, yet, the release of the inorganic component of the glass fibers into the food should be limited to comply with the regulations.
Though its content differs depending on the types, glass fibers usually contain alumina (AI2O3) as one of essential elements. Aluminium (Al), an element present in alumina, that is under control as one of heavy metals when in use in food applications, may be released/leached to foods at particular conditions. Europe has a harmonized legal framework [Regulation (EC) no. 1935/2004] “Basic requirements for materials and articles intended to come into contact with foods ” that requires all food contact materials and articles manufactured, imported and sold in the EU to comply with. In particular, Commission Regulation EU No. 10/2011 stipulates in its Annex II that plastic materials shall not release Al exceeding 1.0 mg/kg of specific migration limit (SML). Also, in the USA, prior approval by the authorities is required in using a new material in food applications.
There is therefore a need for a food container made of or comprising a part in plastic in repeated contact with the food that exhibits mechanical resistance and a limited release of Al into the food. The invention disclosed herein aims at solving this technical problem.
[Brief description of the invention]
The invention is disclosed in the appended claims.
The invention relates to a food container as disclosed in claims 1-15.
The invention also relates to an appliance as disclosed in claim 16.
The invention also relates to the use of composition (C) as disclosed herein for the preparation of a component of a food container. The invention also relates to the use as defined in claim 17.
More details about these inventions are provided herein. [Detailed description of the invention]
Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. In the context of the present invention, the term ‘percent by weight’ (wt%) indicates the content of a specific component in a mixture, calculated as the ratio between the weight of the component and the total weight of the mixture. As used herein, the concentration of recurring units in ‘percent by mol’ (mol%) refers to the concentration relative to the total number of recurring units in the polymer, unless explicitly stated otherwise.
Food container
The invention relates to a food container comprising at least one component that may come into contact with the food and which is made of or comprises a composition (C), the composition (C) comprising a polyamide (PA) as disclosed herein exhibiting a Tg of at least 90.0°C. More precisely, the food container comprises at least one component that may come into contact with the food and which is made of or comprises a composition (C), wherein the composition (C) comprises or consists of:
- at least one polyamide (PA) exhibiting a Tg of at least 90.0 °C;
- from 20.0 to 80.0 wt% of glass fibers (GF) comprising alumina (AI2O3) in an amount of from 9.0 to 25.0 wt% relative to the total weight of the glass fibers (GF), the glass fiber being dispersed in the composition (C), this proportion being relative to the total weight of the composition (C);
- optionally at least one filler (F) different from the glass fiber (GF);
- optionally at least one additive (A) different from the glass fiber (GF) and the filler (F), notably selected in the group consisting of: impact modifiers, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, and any combination thereof. Polyamide (PA) generally comprises at least 90.0 mol% (this proportion being relative to the total number of moles in the polyamide (PA)) of recurring units (RPA) resulting from the polycondensation of a monomer mixture comprising or consisting of:
- at least one phthalic acid selected from the group consisting of o-phthalic acid, isophthalic acid, terephthalic acid and mixtures thereof; and
- at least one diamine selected in the group of the amines of formula (V) H2N-R3- NH2 where R3 is selected from the group consisting of a C4-C18 alkylene group; a C6-C18 cycloalkylene group; a /?/.s(aminomethyl) cyclohexane selected from the group consisting of 1 ,3 -Zhs(aminomethyl)cyclohexane (“1,3-BAC”), 1,4- /v.s(aminomethy l)cyclohexane (“ 1 ,4-B AC”) and combination thereof;
- optionally at least one dicarboxylic acid of formula (IV) HOOC-R2-COOH where R2 is selected from the group consisting of a C4-C18 alkylene, a C4-C30 cycloalkylene and combination thereof.
According to an embodiment, the component is the food container itself, notably when the food container is tiny and/or not complex. Thus, the invention also relates to a food container made of or comprising the composition (C) as disclosed herein.
The food container may be selected in the group consisting of a plate, a bowl, a cup, a food storage container, a pot, a pan, a mixing bowl, a casserole dish, and a food service tray; a food utensil such as a knife, a fork, a spoon, a cooking ustensil, a chopping board and a serving utensil.
The food container may be more particularly be selected in the group consisting of a plate, a bowl, a cup, a food storage container, a pot, a pan, a mixing bowl, a casserole dish, and a food service tray; a food utensil such as a knife, a fork, a spoon, a cooking utensil, a chopping board and a serving utensil. The food container may more particularly be any one of the elements of the previous list.
In particular, the food container may more particularly be a cooking utensil. A cooking utensil is a vessel in which food is prepared and/or stored. The component of the cooking utensil that may come into contact with the food may for instance be the walls of the cooking utensil. For more technically complex cooking utensil, the part that may come into contact with the food may be a means for kneading and/or mixing food, The cooking utensil may be heated thanks to electric heating means close to the vessel. These electric heating means are used to heat the food inside the vessel notably for cooking and/or keeping warm the food. Thus the invention also relates to an appliance comprising the cooking utensil and electric means used to heat the food inside the vessel notably for cooking and/or keeping warm the food.
Composition (C)
Composition (C) comprises or consists of:
- at least one polyamide (PA);
- from 20.0 to 80.0 wt% of glass fibers (GF) comprising alumina (AI2O3) in an amount of from 9.0 to 25.0 wt% relative to the total weight of the glass fibers (GF), the glass fiber dispersed in the composition (C), this proportion being relative to the total weight of the composition (C);
- optionally at least one filler (F) different from the glass fiber (GF);
- optionally at least one additive (A) different from the glass fiber (GF) and the filler (F). and wherein the polyamide (PA) comprises at least 90.0 mol% (this proportion being relative to the total number of moles in the polyamide (PA)) of recurring units (RPA) resulting from the polycondensation of a monomer mixture comprising or consisting of:
- at least one phthalic acid selected from the group consisting of o-phthalic acid, isophthalic acid, terephthalic acid and mixtures thereof; and
- at least one diamine selected in the group of the amines of formula (V) H2N-R3- NH2 where R3 is selected from the group consisting of a C4-C18 alkylene group; a Ce-Cig cycloalkylene group; a /?/.s(aminomethyl) cyclohexane selected from the group consisting of l,3-/>A(aminomethyl)cyclohexane (“1,3-BAC”), 1,4- /v.s(aminomethy l)cyclohexane (“ 1 ,4-B AC”) and combination thereof;
- optionally at least one dicarboxylic acid of formula (IV) HOOC-R2-COOH where R2 is selected from the group consisting of a C4-C18 alkylene, a C4-C30 cycloalkylene and combination thereof. The proportion of recurring units (RPA) is preferably at least 95.0 mol%, preferably at least 99.0 mol%. According to an embodiment, the recurring units of the polyamide (PA) consist of recurring units (RPA).
Composition (C) preferably exhibits a migration of aluminium (Al) lower than 1.0 mg/kg, as measured according to DIN EN 13130-1 :2004. The component of the food container which may come into contact with the food also preferably exhibits a migration of aluminium (Al) lower than 1.0 mg/kg, as measured according to DIN EN 13130-1 :2004. The conditions of the test aims to mimick the repeated contact of the plastic with the food, so that it may be considered as a severe test.
Conditions of the test: the conditions of the test performed to measure the migration of Al are the following: the content of aluminium leached out from composition (C) into an aqueous solution is measured after putting into contact the composition (C) with an aqueous solution of acetic acid (30 g of acetic acid with distilled water to a volume of IL); conditions: 24 hours; 100°C . The test shall be carried out three times on a single sample using fresh solution on each occasion. Compliance with the test shall be checked on the basis of the level of the migration found in the third test.
The aluminium content in the aqueous solution can be determined by any available analytical technique such ICP-MS (inductively coupled plasma - mass spectrometry).
The conditions of the test as disclosed in the experimental section could more particularly be used.
The migration of Al is preferably 0.5 mg/kg or less, preferably 0.2 mg/kg or less, as measured according to the conditions disclosed herein.
Polyamide (PA) is based on the polycondensation of a monomer mixture that comprises at least one phthalic acid selected from the group consisting of o-phthalic acid, isophthalic acid, terephthalic acid and mixtures thereof. The phthalic acid is more particularly selected in the group consisting of isophthalic acid, terephthalic acid and mixtures thereof. The phthalic acid may more particularly be terephthalic acid or a combination of terephthalic acid and isophthalic acid.
The monomer mixture may also comprise at least one dicarboxylic acid of formula (IV) HOOC- R2-COOH where R2 is selected from the group consisting of C4-C18 alkylenes, C4-C30 cycloalkylenes and combination thereof. R2 may more particularly be a C4-C8 alkylene, a C4-C10 cycloalkylene or a combination thereof. This dicarboxylic acid may more particularly be selected in the group consisting of adipic acid, 1 ,3 -cyclohexanedicarboxylic acid, 1,4- cyclohexanedicarboxylic acid and combination thereof. This dicarboxylic acid may be adipic acid or 1 ,4-cyclohexanedi carboxylic acid.
The monomer mixture comprises at least one diamine selected in the group of i) the amines of formula (V) H2N-R3-NH2 where R3 is selected from the group consisting of C4-C18 alkylene groups and Ce-Cis cycloalkylene groups; ii) a /u.s(aminomethyl) cyclohexane selected from the group consisting of 1 ,3 -/?/.s(aminomethyl (cyclohexane (“1,3-BAC”), 1 ,4-/v.s(aminomethyl (cyclohexane (“1,4-BAC”) and combination thereof. This diamine is more particularly selected in the group of (i) the amines of formula (V) where R3 is selected from the group consisting of C4-C12 alkylene groups; a /u.s(aminomethyl) cyclohexane selected from the group consisting of 1,3- /v.s(aminomethyl (cyclohexane (“1,3-BAC”), 1 ,4-/?/.s(aminomethyl (cyclohexane (“1,4-BAC”) and combination thereof.
R3 may more particularly a radical derived from an aliphatic diamine selected from the group consisting of hexamethylenediamine, 1,9-nonanediamine, 1 , 10-diaminodecane, 1,12- diaminododecane, 2-methyl-octanediamine, 2-methyl-l,5-pentanediamine, 1 ,4-diaminobutane.
Polyamide (PA) may more particularly be selected in the group consisting of the following polyamides: 6T/66; 6T/6I; 6T/6I/66; 6T/BACT/10T where BAC is 1,3-BAC and/or 1,4-BAC, preferably 1,3-BAC; polyamides with recurring units (RPA) formed the polycondensation of a monomer mixture consisting of T; 1 ,4-cyclohexanedicarboxylic acid; 1,6-diaminohexane and 1,10-diaminodecane; polyamides with recurring units (RPA) formed the polycondensation of a monomer mixture consisting of T; 1 ,4-cyclohexanedicarboxylic acid; 1 ,6-diaminohexane and 1 ,9- diaminononane and combination thereof.
The proportion of the GF(s) in composition (C) is between 20.0 and 80.0 wt%. This proportion may be between 20.0 and 50.0 wt%.
The proportion of the polyamide(s) (PA) in compostion (C) is preferably at least 50.0 wt%, preferably at least 55.0 wt%.
The total proportion of fdler(s) (F) and additive(s) (A) is generally lower than 20.0 wt%, preferably lower than 10.0 wt%, preferably lower than 5.0 wt%. These proportions are given relative to the total weight of the composition (C).
Suitable polyamides are commercially available under the trade name AMODEL® from Solvay Specialty Polymers USA, LLC.
Physico-chemical properties of the polyamide (PA)
Polyamide (PA) has a melting point (Tm) of at least 275°C, preferably at least 290°C, more preferably at least 305°C, preferably at least 310°C and/or of at most 350°C, preferably at most 340°C, more preferably at most 330°C, as measured according to ASTM D3418.
Polyamide (PA) has a glass transition temperature (Tg), as measured according to ASTM D3418, of at least 90°C, more preferably at least 100°C, more preferably at least 120°C, and/or of at most 220°C, preferably at most 200°C, more preferably at most 180°C.
Polyamide (PA) is semi-crystalline. Polyamide (PA) has a heat of fusion (Hm) of at least 10.0 J/g, preferably at least 20.0 J/g, preferably at least 30.0 J/g and/or of at most 100.0 J/g, preferably at most 90.0 J/g, more preferably at most 80.0 J/g, as measured according to ASTM D3418. As used herein, when referring to ‘glass transition temperature’ (Tg) and ‘melting temperature’ (Tm) for the polyamide, Tg and Tm are measured according to ASTM D3418, unless stated otherwise.
Polyamide (PA) is formed by polycondensation of a monomer mixture as disclosed herein. The polycondensation is performed the monomer mixture in presence of less than 60 wt% of water, preferentially less than 50 wt%, up to a temperature of at least Tm + 10°C, Tm being the melting temperature of the polyamide (PA) wherein wt% is relative to the total weight of the reaction mixture. The temperature at which the polycondensation is performed is generally at least 200°C.
The monomer mixture is such that the molar ratio [-COOH]/[-NH2] is from 0.9 to 1.1, preferably from 0.95 to 1.07, more preferably 1.00 to 1.05, where [-COOH] and [-NH2] are the number of moles of -NH2 and -COOH groups from the monomers in the monomer mixture.
The reaction mixture preferably comprises a catalyst. The catalyst of polycondensation may be selected in the group consisting of phosphorous acid, ortho-phosphoric acid, meta-phosphoric acid, alkali-metal hypophosphite such as sodium hypophosphite and phenylphosphinic acid. A convenient catalyst used is sodium hypophosphite. The reaction mixture generally also further comprise at least one end-capping agent as disclosed above. The end-capping agent may notably be used to control the molecular weight.
The end -groups of the polyamide (PA) are selected in the group of-NH2, -COOH and amide end- groups. Indeed, the end-groups in the polyamide (PA) may be -NH2 or -COOH. Yet, when the polycondensation involves the addition of an end-capping agent, these end-groups may be converted, partially or totally, into amide end-groups.
The amide end groups are of formula -NH-C(=O)-R where R is an an alkyl group, an aryl group or a cycloalkyl group and/or of formula -C(=O)-NH-R' where R' is an alkyl group or a cycloalkyl group. R is more particularly a linear or branched C2-C18 alkyl group or a C5-C10 cycloalkyl group. R' is more particularly a linear or branched C2-C18 alkyl group. The amide end groups of formula -NH-C(=O)-R result from the reaction of the end-groups -NH2 with a monocarboxylic acid (end- capping agent) of formula R-COOH. The monocarboxylic acid (end-capping agent) may advantageously be selected in the group consisting of benzoic acid; cyclohexanoic acid; R-COOH where R is a linear or branched C2-C18 alkyl group and combination of two or more of these acids. R is the radical derived from the acid of formula R-COOH. The monocarboxylic acid (end-capping agent) may more particularly be selected in the group consisting of acetic acid, propanoic acid, butyric acid, valeric acid, caproic acid, lauric acid, stearic acid, 2-ethylhexanoic acid, cyclohexanoic acid, benzoic acid and combination of two or more of these acids. The monocarboxylic acid (end-capping agent) is more particularly of formula CH3-(CH2)n-COOH where n is an integer between 0 and 16. The amide end groups are then of formula -NH-C(=O)- (CH2)n-CH3.
The amide end groups of formula -C(=O)-NH-R' result from the reaction of the end-groups - COOH with a primary amine (end-capping agent) of formula R-NH2. The primary amine (endcapping agent) may advantageously be selected in the group consisting of the amines of formula R-NH2 where R' is a linear or branched C2-C18 alkyl group. R' is the radical derived from the amine of formula R-NH2. The primary amine (end-capping agent) is more particularly of formula CH3-(CH2)n-NH2 where n' is an integer between 2 and 18. The amide end groups are then of formula -C(=O)-NH-(CH2)n'-CH3. The primary amine (end capping agent) may more particularly be selected in the group consisting of propyl amine, butylamine, pentylamine, hexylamine, 2- ethylhexylamine, n-octylamine, n-dodecylamine, n-tetradecylamine, n-hexadecylamine, stearylamine, cyclohexylamine and combination of two or more of these amines.
The proportion of the end groups can be quantified by 'H NMR or by potentiomtric techniques.
Composition (C) may be prepared by melt-blending the polyamide (PA) and the other components of the composition (C). Melt-blending is usually performed by using a melt mixer selected in the group consisting of an extruder (e.g. a single screw extruder or a twin screw extruder), a single screw, a twin screw kneader and a Banbury mixer. Melt-blending is conveniently performed with an extruder (e.g. a single screw extruder or a twin screw extruder). Composition (C) comprises at least one polyamide (PA). It may comprise only one polyamide (PA) or more than one polyamides (PA). According to a preferred embodiment, the composition (C) does not comprise any polyamide other than polyamide(s) (PA).
GLASS FIBER (GF)
Composition comprises at least one glass fiber (GF). Glass fibers are silica-based glass compounds that contain several metal oxides which can be tailored to create different types of glass. The main oxide is silica (SiCh) in the form of silica sand; the other oxides such as calcium oxide (CaO), sodium oxide (Na20) and alumina (AI2O3) are incorporated to adjust the properties of interest, e.g. to lower the melting temperature and to impede crystallization.
The glass fibers may be endless glass fibers or chopped glass fibers.
In the present invention, the glass fiber comprises alumina (AI2O3) in an amount of from 9.0 to 25.0 wt%, relative to the total weight of the glass fiber (GF). This proportion is preferably between 12.0 and 20.0 wt%, preferably between 12.0 and 17.0 wt%.
In one embodiment, the glass fibers (GF) have an average length of from 3 mm to 50 mm. In some such embodiments, the glass fibers have an average length of from 3 mm to 10 mm, from 3 mm to 8 mm, from 3 mm to 6 mm, or from 3 mm to 5 mm. In alternative embodiments, the glass fibers have an average length of from 10 mm to 50 mm, from 10 mm to 45 mm, from 10 mm to 35 mm, from 10 mm to 30 mm, from 10 mm to 25 mm or from 15 mm to 25 mm.
In some embodiments, the glass fibers have generally an equivalent diameter of from 5 to 20 pm, preferably of from 5 to 15 pm, more preferably of from 5 to 10 pm.
In some embodiments, the glass fiber (GF) has high modulus. GF preferably has an elastic modulus of at least 76 GPa, preferably at least 78 GPa, more preferably at least 80 GPa, and most preferably at least 82 GPa, as measured according to ASTM D2343. The morphology of the glass fiber is not particularly limited. The glass fiber can have a circular cross-section (‘round glass fiber’) or a non-circular cross-section (‘flat glass fiber’). Examples of suitable flat glass fibers include, but are not limited to, glass fibers having oval, elliptical and rectangular cross sections.
In some embodiments in which the composition includes a flat glass fiber, the flat glass fiber has a cross-sectional longest diameter of at least 15 pm, preferably at least 20 pm, more preferably at least 22 pm, still more preferably at least 25 pm. Additionally or alternatively, in some embodiments, the flat glass fiber has a cross-sectional longest diameter of at most 40 pm, preferably at most 35 pm, more preferably at most 32 pm, still more preferably at most 30 pm. Additionally or alternatively, in some embodiments, the flat glass fiber has a cross-sectional shortest diameter of at most 25 pm, preferably at most 20 pm, more preferably at most 17 pm, still more preferably at most 15 pm. In some embodiments, the flat glass fiber has a cross-sectional shortest diameter was in the range of 5 to 20 pm, preferably of 5 to 15 pm, more preferably of 7 to 11 pm.
In some embodiments, the flat glass fiber has an aspect ratio, defined as the average ratio between the length and the largest of the width and thickness, of at least 2, preferably at least 2.2, more preferably at least 2.4, still more preferably at least 3. The aspect ratio is defined as a ratio of the longest diameter in the cross-section of the glass fiber to the shortest diameter in the same crosssection. Additionally or alternatively, in some embodiments, the flat glass fiber has an aspect ratio of at most 8, preferably at most 6, more preferably of at most 4. In some embodiments, the flat glass fiber has an aspect ratio of from 2 to 6, and preferably, from 2.2 to 4.
In some embodiments, in which the glass fiber is a round glass fiber, the glass fiber has an aspect ratio of less than 2, preferably less than 1.5, more preferably less than 1.2, even more preferably less than 1.1, most preferably, less than 1.05.
Of course, the person of ordinary skill in the art will understand that regardless of the morphology of the glass fiber (e.g. round or flat), the aspect ratio cannot, by definition, be less than 1. ADDITIVE(S)
In the present invention, the composition may comprise at least one additive (A), which is different from the glass fiber (GF).
In a preferred embodiment, the proportion of additive(s) (A) is at least 0.1 wt%, preferably at least 0.2 wt%, more preferably at least 0.4 wt%, most preferably at least 0.5 wt%, and/or of at most 20.0 wt%, preferably at most 17.0 wt%, more preferably at most 15.0 wt%, most preferably at most 10.0 wt%, based upon the total weight of composition (C). In a particularly preferred embodiment, the additive(s) (A) is/are comprised in an amount of from 0.1 wt% to 5.0 wt%, preferably from 0.2 wt% to 3.0 wt%, more preferably from 0.4 wt% to 2.0 wt%, most preferably 0.5 wt% to 1.0 wt%, based upon the total weight of composition (C).
The additive (A) is generally selected from the group consisting of impact modifiers, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants (e.g. linear low density polyethylene (LLDPE), calcium stearate, magnesium stearate or sodium montanate), thermal stabilizers, light stabilizers, antioxidants, nucleating agents, polymer processing aids, antiblocking agents, slip agents, antifogging agents, chemical blowing agents, nucleating agents, and any combination thereof. In a more particular embodiment, the additive (A) is selected from the group consisting of impact modifiers, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, and any combination thereof.
Composition (C) preferably comprises at least one impact modifier as an additive. The impact modifier useful herein is not particularly limited, so long as it imparts useful properties to the polyamide, such as sufficient tensile elongation at yield and break. Useful impact modifiers include polyolefins, preferably functionalized polyolefins, and especially elastomers such as styrene- ethylene-butylene-styrene (SEBS) and ethylene-propylene-diene monomer (EPDM). In a preferred embodiment, the impact modifier is selected from the group consisting of a maleic anhydride functionalized EPDM rubber, a maleic anhydride functionalized SEBS block copolymer, and mixtures thereof. Useful functionalized polyolefin impact modifiers are available from various commercial sources, including maleated polypropylenes and ethylene-propylene copolymers available as EXXELOR™ PO and maleic anhydride-functionalized ethylene-propylene copolymer rubber comprising about 0.6 wt% of pendant succinic anhydride groups, such as EXXELOR® RTM VA 1801 from the Exxon Mobil Chemical Company; acrylate-modified polyethylenes available as SURLYN®, such as SURLYN® 9920, methacrylic acid-modified polyethylene from the DuPont Company; and PRIMACOR®, such as PRIMACOR® 1410 XT, acrylic acid-modified polyethylene, from the Dow Chemical Company; maleic anhydride-modified SEBS block copolymer, such as KRATON® FG1901X, a SEBS that has been grafted with about 2 wt% of maleic anhydride, available from Kraton Polymers; maleic anhydride-functionalized EPDM terpolymer rubber, such as ROYALTUF® 498, from the SI Group. Still other impact modifiers useful herein include acrylic impact modifiers commercialized as Paraloid® impact modifiers by Rohm & Haas. Suitable functional groups on the impact modifier include any chemical moieties that can react with end groups of the polyamide to provide enhanced adhesion to the high temperature matrix.
The impact modifier and the polyamide can be mixed together in any manner, and mixing can occur, for instance, before extrusion or the materials may be mixed in the extruder.
FILLER (F)
The composition (C) may comprise at least one filler which is different from glass fibers, as described above. A large selection of fillers may be added to the composition according to the present invention, which can be selected from fibrous and particulate fillers.
A fibrous filler is considered herein to be a material having length, width and thickness, wherein the average length is significantly larger than both the width and thickness. Generally, such a material has an aspect ratio of at least 5, at least 10, at least 20 or at least 50. In some embodiments, the fibrous fillers (e.g. carbon fibers) have an average length of from 3 mm to 50 mm. In alternative embodiments, the fibrous fillers have an average length of from 10 mm to 50 mm. The average length of the fibrous filler can be taken as the average length of the fibrous filler prior to incorporation into the composition or can be taken as the average length of the fibrous filler in the composition. A particulate filler may be selected from mineral fillers (e.g. talc, mica, kaolin, calcium carbonate, calcium silicate, magnesium carbonate) and glass balls (e.g. hollow glass microspheres).
The invention will now be described with reference to the following examples, whose purpose is merely illustrative and not intended to limit the scope of the invention.
[EXPERIMENTAL SECTION]
The following examples demonstrate the Al leaching/migration in the glass fibers and in the compositions compounded with a polyamide and glass fibers.
Raw Materials:
The raw materials used to form the samples are as provided below:
• Polyamide: Amodel® 8004, commercially available from Solvay Specialty Polymers USA, L.L.C.
• Glass fibers (GF):
GF1 : 3B Advantex®, commercially available from 3B Fibreglass Company
GF2: OCV FC Advantex®, commercially available from Owens Corning GF3: NEG 3610 ECR, commercially available from Nippon Electric Glass GF4: CPIC CS HL (301), commercially available from Chongqing Polycomp International Corp.
• Talc: Mistron® Vapor, commercially available from Imerys
• Carbon black: MPC Channel Black, commercially available from Milliken & Company
• Linear low-density polyethylene (LLDPE): Petrothene® GA564189, commercially available from Lyondell Basell.
To manufacture test samples, Amodel® 8004 was compounded at 350°C by using a double screw extruder with the components as disclosed in Table 1. TABLE 1
Figure imgf000018_0001
The content of Al (that is the elemental composition) in glass fibers was determined by Scanning Electron Microscopy (SEM)/ Energy Dispersive X-ray Spectroscopy (EDS) as 7.8 wt%, 8.2 wt%, 9.5 wt% and 10.5 wt%, corresponding to alumina (AI2O3) content of 14.7 wt%, 15.5 wt%, 17.9 wt% and 19.8 wt%, respectively.
The elemental composition of surfaces of glass fibers (about 0.01 to 1.0 um in SEM) was performed by EDS. In this technique, the energy of X-ray signals generated by electron beam hitting the sample surface was measured. This was made under the assumption that the composition of glass fibers on the surface are equivalent to the composition in the bulk barring the presence of glass fiber sizing which is limited to few angstroms (A) on the surface.
This technique has a high degree of precision, especially when used to examine a defined area or line on the surface of metals and/or ceramics. Sample was first sputter-coated with Au/Pd to promote conductivity and reduce beam damage to the sample during imaging. The target area was identified and focused on by SEM (Zeiss Sigma 300). To acquire an EDS spectrum, a Bruker XFlash® detector was used. Characteristic X-ray photons were generated simultaneously with scanning electron imaging and were collected by the EDS detector. EDS spectra were then collected at each point in the image and compiled into an EDS map. A collective average spectra were generated based on elemental abundance across the entire field of view and elements present were assigned based on X-ray characteristic to each element.
Conditions of the test according to DIN EN 13130-1 :2004: to test Al leaching/migration from the glass fibers and composition (C), plaques of the composition (60x60x3 mm length breadth height) were molded and tested according to DIN EN 13130-1 and put in contact (24 hours / 100°C) with an aqueous solution of acetic acid at 3% (w/v) (30 g of acetic acid with distilled water to a volume of 1 L) Inductively coupled plasma - mass spectrometry (“ICP-MS”), e.g. Agilent 7900, was used to determine the amount of Al in the solution.
Table 2 shows the Al content in glass fibers, resulting from the different content of alumina therein, and the Al leaching test results that were implemented three times, without being compounded with polyamide, talc, carbon black and/or LLDPE.
TABLE 2
Figure imgf000019_0001
Table 3 shows the Al leaching test results of the compositions comprising said glass fibers, polyamide, talc, carbon black and/or LLDPE (i.e. being compounded).
TABLE 3
Figure imgf000019_0002
First, the inventive examples of El and E2 satisfied all the requirements, i.e. M3 < specific migration limit (SML); Ml > M2 > M3; and Ml, M2 and M3 should be less than SML, respectively, when SML is not detected. SML is maximum permitted level of Al migrating from the final material/article into the food simulant. SML of Al is 1.0 mg/kg under Commission Regulation (EU) No. 10/2011 (Annex II).
It was surprisingly found by the inventors that the relative quantities of alumina in glass fibers are not commensurate with the migration behaviour of Al in the glass fibers. Moreover, the inventors found that, once the glass fibers are compounded with a polyamide, there is an unexpected synergistic effect brought by compounding, which results in unusually low, preferably non- detectable, specific migration limit of Al.
Referring to Tables 2 and 3, the samples including glass fibers containing Al no greater than 9.0 wt% had significantly reduced Al leaching, relative to samples including glass fibers containing Al greater than 9.0 wt%. The synergistic effect of the glass fibers, which contain Al no greater than 9.0 wt%, compounded with the polyamide was demonstrated by comparison of the leaching data in Tables 2 and 3. For example, despite the fact that GF1 and GF3 have a difference in Al content of about 18% (7.8 vs. 9.5) and the difference in total leaching of about 21% (35.0 vs. 44.5), the difference in total leaching between El (incorporating GF1) and CE1 (incorporating GF3) was much higher than 1,200% (0.3 vs. 3.85). Still further, comparison of El and E2 with CE1 to CE3 demonstrate that the leaching results are unexpected. For example, comparison of CE1 with CE2 and CE3 demonstrates that compositions incorporating a mixture of glass fibers having Al content of no greater than 9.0 wt% and greater than 9.0 wt% (CE2 and CE3), the total leaching was greater than analogous composition incorporating glass fibers having greater than 9.0 wt% of Al (CE1) and analogous compositions incorporating glass fibers having no greater than 9.0 wt% of Al (El and E2).

Claims

1. A food container comprising at least one component that may come into contact with the food wherein the component is made of or comprises a composition (C) and wherein the composition (C) comprises or consists of:
- at least one polyamide (PA) exhibiting a Tg of at least 90.0 °C as measured according to ASTM D3418;
- from 20.0 to 80.0 wt% of glass fibers (GF) comprising alumina (AI2O3) in an amount of from 9.0 to 25.0 wt% relative to the total weight of the glass fibers (GF), the glass fiber being dispersed in the composition (C), this proportion being relative to the total weight of the composition (C);
- optionally at least one filler (F) different from the glass fiber (GF);
- optionally at least one additive (A) different from the glass fiber (GF) and the filler (F), notably selected in the group consisting of: impact modifiers, tougheners, plasticizers, colorants, pigments, antistatic agents, dyes, lubricants, and any combination thereof; wherein polyamide (PA) comprises at least 90.0 mol% (this proportion being relative to the total number of moles in the polyamide (PA)) of recurring units (RPA) resulting from the polycondensation of a monomer mixture comprising or consisting of:
- at least one phthalic acid selected from the group consisting of o-phthalic acid, isophthalic acid, terephthalic acid and mixtures thereof; and
- at least one diamine selected in the group of the amines of formula (V) H2N-R3- NH2 where R3 is selected from the group consisting of a C4-C18 alkylene group; a Ce-Cig cycloalkylene group; a /?/.s(aminomethyl) cyclohexane selected from the group consisting of l,3-/>A(aminomethyl)cyclohexane (“1,3-BAC”), 1,4- /v.s(aminomethy l)cyclohexane (“ 1 ,4-B AC”) and combination thereof;
- optionally at least one dicarboxylic acid of formula (IV) HOOC-R2-COOH where R2 is selected from the group consisting of a C4-C18 alkylene, a C4-C30 cycloalkylene and combination thereof.
2. Food container according to claim 1, wherein composition (C) exhibits a migration of aluminium (Al) lower than 1.0 mg/kg, as measured according to DIN EN 13130-1 :2004.
3. Food container according to claim 1 or 2, wherein composition (C) exhibits a migration of aluminium (Al) lower than 1.0 mg/kg, under the following conditions: the content of aluminium leached out from composition (C) into an aqueous solution is measured after putting into contact the composition (C) with an aqueous solution of acetic acid (30 g of acetic acid with distilled water to a volume of IL); conditions of contact: 24 hours; 100°C, the test being carried out three times on a single sample using fresh solution on each occasion, the compliance with the test being checked on the basis of the level of the migration found in the third test.
4. Food container according to any one of the preceding claims, wherein the proportion of glass fibers is between 20.0 and 50.0 wt%, this proportion being given relative to the total weight of the composition (C).
5. Food container according to any one of the preceding claims, wherein the proportion of the polyamide(s) (PA) in compostion (C) is preferably at least 50.0 wt%, preferably at least 55.0 wt%, this proportion being given relative to the total weight of the composition (C).
6. Food container according to any one of the preceding claims, wherein the total proportion of filler(s) (F) and additive(s) (A) is lower than 20.0 wt%, preferably lower than 10.0 wt%, preferably lower than 5.0 wt%, this proportion being given relative to the total weight of the composition (C).
7. Food container according to any one of the preceding claims, wherein the glass fiber (GF) comprises alumina in an amount of from 12.0 to 20.0 wt%, preferably between 12.0 and 17.0 wt%, this proportion being relative to the total weight of the glass fiber (GF).
8. Food container according to any one of claims 2-7, wherein the migration of Al is 0.5 mg/kg or less, preferably 0.2 mg/kg or less..
9. Food container according to any one of claims 1 to 8, wherein the polyamide (PA) has a melting point (Tm) of at least 180°C, preferably at least 210°C, more preferably at least 240°C, and/or of at most 350°C, preferably at most 340°C, more preferably at most 330°C, as measured according to ASTM D3418.
10. Food container according to any one of claims 1 to 9, wherein the polyamide (PA) has a glass transition temperature (Tg), as measured according to ASTM D3418, of at least 90°C, more preferably at least 100°C, and/or of at most 220°C, preferably at most 200°C, more preferably at most 180°C.
11. Food container according to any one of claims 1 to 10, wherein the polyamide (PA) has a heat of fusion of at least 10.0 J/g, and/or of at most 100.0 J/g, preferably at most 90.0 J/g, more preferably at most 80.0 J/g, as measured according to ASTM D3418.
12. Food container according to any one of the preceding claims, wherein composition (C) comprises at least one impact modifier as an additive (A) selected from the group consisting of a maleic anhydride functionalized ethylene-propylene-diene monomer rubber, a maleic anhydride functionalized styrene-ethylene-butylene-styrene block copolymer, and mixtures thereof.
13. Food container according to any one of the preceding claims, wherein the filler (F) is selected from the group consisting of calcium carbonate, magnesium carbonate, graphite, carbon black, carbon fiber, carbon nanofiber, graphene, graphene oxide, fullerene, talc, wollastonite, mica, alumina, silica, titanium dioxide, kaolin, silicon carbide, zirconium tungstate, boron nitride, wherein the filler is different from the glass fiber.
14. Food container according to any one of the preceding claims, wherein the food container is a plate, a bowl, a cup, a food storage container, a pot, a pan, a mixing bowl, a casserole dish, and a food service tray; a food utensil such as a knife, a fork, a spoon, a cooking ustensil, a chopping board or a serving utensil.
15. Food container according to any one of the preceding claims, wherein the food container is a cooking utensil.
16. Appliance comprising the food container according to claim 14 or 15 and and electric means used to heat the food inside the food container, notably for cooking and/or keeping warm the food.
17. Use of a composition (C) as disclosed in any one of the previous claims for the preparation of a component of a food container.
PCT/EP2023/066294 2022-06-16 2023-06-16 Food container comprising a reinforced polyamide composition exhibiting a slow release of aluminium WO2023242415A1 (en)

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