Antimicrobial heat seal coating compositions

Abstract

Disclosed is an antimicrobial heat seal coating composition comprising (A) a copolymer dispersed in a solvent, the copolymer comprising at least one selected from the group consisting of: a (meth)acrylate (co)polymer, an olefin (co)polymer, a copolymer comprising a (meth)acrylate unit and an olefin unit, and (B) an antimicrobial agent. Also disclosed is a food packaging article comprising the disclosed heat seal coating. When applied to food packaging applications such as dairy packaging applications, the disclosed coating provides reduced hydrogen peroxide handling exposure and improved packaging reliability.

Description

Technical Field

[0001] The present invention relates to an antimicrobial heat seal coating. The disclosed antimicrobial heat seal coating is particularly suitable for food packaging applications, such as dairy product packaging.

[0002] In some embodiments, the disclosed heat seal coating comprises (A) a copolymer dispersed in a solvent, the copolymer comprising at least one selected from the group consisting of: (meth)acrylate (co)polymers, olefin (co)polymers, copolymers comprising (meth)acrylate units and olefin units, and combinations thereof, and (B) an antimicrobial agent. A food packaging article is also disclosed, the food packaging article comprising the disclosed heat seal coating.

[0003] When applied in food packaging applications, such as dairy packaging applications, the disclosed coatings provide reduced hydrogen peroxide processing exposure and improved packaging reliability. Background Art

[0004] Heat seal coatings are commonly used in food packaging applications. For example, in dairy packaging, a heat seal coating applied to the cap is often used to heat seal the cap to the container. The container filled with food or beverage is usually made of polypropylene, polystyrene, polyvinyl chloride or polyethylene terephthalate. The cap is usually a multilayer structure, which includes a substrate, usually aluminum foil or polyethylene terephthalate, an ink layer, a protective layer and a primer layer. The heat seal coating is applied to the substrate and then sealed by applying heat and / or pressure to the container.

[0005] Heat seal coatings typically include organic dispersions of copolymers of (meth)acrylates and olefins. These polymers are dissolved in a solvent, such as a mixture of butyl acetate and methyl ethyl ketone, to form a heat seal coating that is applied to the lid with a gravure roller, followed by a thorough drying process. For dairy applications, such coatings are applied at a coating weight between 3.5 and 4.5 g / m 2 (after drying) and can reach 6 g / m2 when applied to aluminum substrates 2 After sealing in a container, the resulting seal strength is typically about 8 N / 15 mm.

[0006] Heat seal coatings used in dairy packaging applications must demonstrate high resistance to water and fruit acids (e.g. citric acid, lactic acid). Since the closure is fully coated, i.e. not only on the periphery in contact with the container, the heat seal coating is in direct contact with the food or beverage. Therefore, all coatings must comply with current food regulations, which apply to direct food contact.

[0007] The filling of dairy product packaging must be done under aseptic conditions. The capping and container materials must be treated with high concentrations of hydrogen peroxide to avoid cross contamination of bacteria, sperm and fungi. If aseptic conditions are not met, the packaged dairy products will be affected. Hydrogen peroxide is widely used in the dairy industry, among other treatment possibilities (e.g., UV, steam), but it requires special and / or expensive safety precautions to protect workers from exposure to hydrogen peroxide.

[0008] Therefore, there is a need for heat seal coatings for food packaging applications that reduce worker exposure to hydrogen peroxide and provide maintained and / or improved reliability. Summary of the invention

[0009] Such heat seal coatings are disclosed herein. In some embodiments, an antimicrobial heat seal coating is disclosed, comprising (A) a copolymer dispersed in a solvent, the copolymer comprising at least one selected from the group consisting of: a (meth)acrylate (co)polymer, an olefin (co)polymer, a copolymer comprising a (meth)acrylate unit and an olefin unit, and a combination thereof, and (B) an antimicrobial agent.

[0010] Also disclosed are food packaging articles comprising the disclosed heat seal coatings.

[0011] When applied in food packaging applications, such as dairy packaging applications, the disclosed coatings provide reduced hydrogen peroxide processing exposure and improved packaging reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Refer to the following diagram, where:

[0013] Figure 1 Shown is a graph illustrating the survival rate of E. coli after 24 hours of incubation using various Examples.

[0014] Figure 2 Shown is a graph illustrating the survival rate of Listeria monocytogenes after 24 hours of incubation using various Examples. DETAILED DESCRIPTION

[0015] An antimicrobial heat seal coating is disclosed, comprising (A) a copolymer dispersed in a solvent, the copolymer comprising at least one selected from the group consisting of: a (meth)acrylate (co)polymer, an olefin (co)polymer, a copolymer comprising a (meth)acrylate unit and an olefin unit, and combinations thereof, and (B) an antimicrobial agent.

[0016] (A) Copolymer dispersion

[0017] In some embodiments, the copolymer dispersed in the solvent includes at least one selected from the group consisting of: a (meth)acrylate (co)polymer, an olefin (co)polymer, a copolymer including a (meth)acrylate unit and an olefin unit, and combinations thereof.

[0018] The (meth)acrylate (co)polymer or (meth)acrylate unit of the block or graft copolymer comprises a (meth)acrylate of a C1-C20 alkyl alcohol, such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate or 2-ethylhexyl (meth)acrylate, and one or more ethylenically unsaturated monomers selected from the group consisting of styrene, α-methylstyrene, vinyl chloride, vinyl acetate, vinyl stearate, vinyl methyl ketone, vinyl isobutyl ether, allyl acetate, allyl chloride, allyl isobutyl ether, allyl methyl ketone, dibutyl maleate, dilauryl maleate, dibutyl itaconate, vinyl pyridine, vinyl pyrrolidine, vinyl pyrrolidone, vinyl carbazole, vinyl imidazole and alkane thereof. The invention also includes butane derivatives, hydroxyalkyl and dialkylaminoalkyl (meth)acrylates, and in particular dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, hydroxyethyl (meth)acrylate, hydroxy-n-propyl (meth)acrylate or hydroxy-n-butyl (meth)acrylate, non-aromatic hydrocarbons having 2 to 8 carbon atoms and at least 2 olefinic double bonds (for example butadiene, isoprene or chloroprene), 2-ethoxyethyl acrylate, 2-butoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, phenylethyl (meth)acrylate, phenylpropyl (meth)acrylate, (meth)acrylates of heterocyclic alcohols (for example furfuryl (meth)acrylate), (meth)acrylamide and C1-C4-alkyl-substituted derivatives thereof on the nitrogen.

[0019] The olefin (co)polymers or olefin units of the block or graft copolymers consist of ethylene, propylene, butene and / or other α-olefins having 5 to 20 carbon atoms. Propylene polymers are particularly suitable.

[0020] In general, copolymer (A) is provided as a dispersion in an organic solvent, wherein the solids content of the dispersion is between 30% and 60%, preferably between 40% and 50%, according to ISO 3251. Preferably, the solvent is a solvent mixture comprising one or more esters of an aliphatic carboxylic acid with an aliphatic alcohol and one or more ketones. Aliphatic carboxylic acids that can be used are acetic acid, propionic acid or butyric acid. Aliphatic alcohols that can be used are ethanol, propanol, isopropanol, n-butanol, 2-butanol, 2-methyl-1-propanol or 2-methyl-2-propanol. Examples of ketones that can be used are acetone or methyl ethyl ketone.

[0021] In some embodiments, the copolymer dispersed in solvent (A) has a glass transition temperature of -60 to -30°C or -50 to -40°C as measured by differential scanning calorimetry according to ISO 11357-1.

[0022] In some embodiments, the copolymer dispersion (A) comprises 90 to 99.9, or 95 to 99.9, or 98 to 99.9 weight percent of the total weight of the antimicrobial heat seal coating composition.

[0023] (B) Antimicrobial Agents

[0024] In some embodiments, the antimicrobial heat seal coating composition includes an antimicrobial. In some embodiments, the antimicrobial is a substance that has an impact on the growth of bacteria, fungi and yeast. Suitable antimicrobials include, but are not limited to, essential oils, sulfur dioxide, chlorine dioxide, chitosan, silver ions in a zeolite matrix, nisin, sorbic acid, lactic acid, benzoic acid, allyl isothiocyanate and combinations thereof. In some embodiments, suitable antimicrobials can be classified as "natural", "synthetic" or "metal-based". "Natural" refers to naturally derived substances, while "synthetic" refers to substances formulated synthetically. The effect principle distinguishes between substances that require direct surface contact (e.g., metal) or that volatile components are sprayed into the head space of the package.

[0025] In some embodiments, the antimicrobial agent (B) comprises 0.1 to 10, or 0.1 to 5, or 0.1 to 1 weight percent of the total weight of the antimicrobial heat seal coating composition.

[0026] Optional components

[0027] In some embodiments, the disclosed antimicrobial heat seal coating composition may optionally include an antioxidant. For example, a hindered phenolic antioxidant may be included in the composition. As shown in the examples, the inclusion of an antioxidant can further improve the antimicrobial properties of the disclosed composition.

[0028] In some embodiments, the antioxidant comprises 0.1 to 1, or 0.1 to 0.5, or 0.1 to 0.3 weight % of the total weight of the antimicrobial heat seal coating composition.

[0029] In some embodiments, the disclosed antimicrobial heat seal coating compositions may optionally include an anti-filler. For example, an inorganic filler such as talc or untreated precipitated silica may be included in the composition.

[0030] In some embodiments, the disclosed antimicrobial heat seal coating composition may optionally include an anti-sticking agent. Suitable anti-sticking agents include inorganic materials such as talc or other silica derivatives. Suitable commercially available anti-sticking agents include those available from Evonik under the trade name ACEMATTTM and AEROSIL TM Anti-sticking agent sold by name.

[0031] In some embodiments, when the composition is used on an aluminum foil surface, the disclosed antimicrobial heat seal coating composition may include a vinyl chloride vinyl acetate ("VMCH") copolymer resin. Suitable commercially available VMCH resins include those sold by The Dow Chemical Company under the name UCAR TM Those VMCH resins sold by VMCH.

[0032] Examples of the present invention

[0033] The present invention will now be explained in further detail by describing examples (illustrative example "IE", comparative example "CE", collectively referred to as "examples") illustrating the disclosed adhesive composition and existing adhesive compositions. However, the scope of the present invention is certainly not limited to the examples.

[0034] Comparative Example 1 ("CE1") includes an aluminum foil lidding without a heat seal coating. Comparative Example 2 ("CE2") includes an aluminum foil lidding with a coating weight of 4.5 g / m 2 (dry weight) of a heat seal coated aluminum foil lidding, the heat seal coating comprising DEGALAN TM PM666, available from Evonik, is an organic dispersion of methacrylate and polyolefin in a solvent comprising 70 wt % butyl acrylate and 30 wt % methyl ethyl ketone, having a solids content of 45%, a glass transition temperature of -45°C, and a molecular weight of 300,000 g / mol.

[0035] Illustrative Example 1 ("IE1") included applying a coating weight of 4.5 g / m 2 A heat seal coated aluminum foil cover comprising 99 wt. % DEGALAN in a solvent TM PM 666 and 1 wt% of a zeolite loaded with Ag+ ions having a 100% solids content. Illustrative Example 2 ("IE2") included applying a coating weight of 4.5 g / m 2 A heat seal coated aluminum foil cover comprising 98.8 wt. % DEGALAN in a solvent TM PM 666, 1 wt% of a zeolite loaded with Ag+ ions having a solid content of 100% and 0.2 wt% of IGRANOX which is a hindered phenolic antioxidant TM 1076.

[0036] Examples were tested against the following bacteria: Escherichia coli (Gram-negative fecal indicator strain), Staphylococcus aureus (Gram-positive skin pathogen), Listeria monocytogenes (Gram-positive food pathogen), and Candida albicans (yeast). The analysis of antimicrobial effectiveness was performed according to the surface contact method ISO / DIS 22196:2006.

[0037] Figure 1 and Figure 2 A graph illustrating the effectiveness of IE1 and IE2, which include heat seal coatings into which the antimicrobial agent (zeolite loaded with Ag+ ions) is directly incorporated, is shown. In detail, IE1 and IE2 exhibit significant effects on E. coli and Listeria monocytogenes, and have smaller but still positive effects on Candida albicans and Staphylococcus aureus.

[0038] In addition to the embodiments described above, various embodiments of specific combinations are also within the scope of the present invention, some of which are described below:

[0039] Example 1. An antimicrobial heat seal coating composition comprising:

[0040] (A) a copolymer dispersed in a solvent, the copolymer comprising at least one selected from the group consisting of: a (meth)acrylate (co)polymer, an olefin (co)polymer, a copolymer comprising a (meth)acrylate unit and an olefin unit; and

[0041] (B) Antimicrobial agents.

[0042] Embodiment 2. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the copolymer dispersed in a solvent has a glass transition temperature of -60 to -30°C as measured by differential scanning calorimetry according to ISO 11357-1.

[0043] Embodiment 3. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the copolymer dispersed in a solvent has a glass transition temperature of -50 to -40°C as measured by differential scanning calorimetry according to ISO 11357-1.

[0044] Embodiment 4. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the solvent is selected from the group consisting of butyl acetate, methyl ethyl ketone, and combinations thereof.

[0045] Embodiment 5. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the copolymer dispersed in a solvent has a solids content of 45 wt%.

[0046] Embodiment 6. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent is naturally derived.

[0047] Embodiment 7. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent is synthetically derived.

[0048] Embodiment 8. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent is metal-based.

[0049] Embodiment 9. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent is a substance that negatively affects the growth rate of at least one of bacteria, fungi, and yeast.

[0050] Embodiment 10. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent is selected from the group consisting of essential oils, sulfur dioxide, chlorine dioxide, chitosan, silver ion loaded zeolites, nisin, sorbic acid, lactic acid, benzoic acid, allyl isothiocyanate, and combinations thereof.

[0051] Embodiment 11. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, further comprising an antioxidant.

[0052] Embodiment 12. The antimicrobial heat seal coating composition as described in embodiment 11, wherein the antimicrobial agent is a hindered phenolic antioxidant.

[0053] Embodiment 13. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, further comprising a filler.

[0054] Embodiment 14. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the copolymer dispersion (A) comprises 90 to 99.9 weight percent of the total weight of the composition.

[0055] Embodiment 15. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the copolymer dispersion (A) comprises 95 to 99.9 weight percent of the total weight of the composition.

[0056] Embodiment 16. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the copolymer dispersion (A) comprises 98 to 99.9 weight percent of the total weight of the composition.

[0057] Embodiment 17. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent (B) comprises 0.1 to 10 weight percent of the total weight of the composition.

[0058] Embodiment 18. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent (B) comprises 0.1 to 5 weight percent of the total weight of the composition.

[0059] Embodiment 19. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, wherein the antimicrobial agent (B) comprises 0.1 to 1 weight percent of the total weight of the composition.

[0060] Embodiment 20. An antimicrobial heat seal coating composition comprising:

[0061] (A) ethylene vinyl acetate dispersed in a solvent; and

[0062] (B) Antimicrobial agents.

[0063] Embodiment 21. The antimicrobial heat seal coating composition of any preceding or subsequent embodiment, further comprising a vinyl chloride vinyl acetate copolymer resin.

[0064] Embodiment 22. A food packaging article comprising the antimicrobial heat seal coating composition of any preceding or subsequent embodiment.

[0065] Embodiment 23. A food packaging product, comprising:

[0066] including the cover of the surface; and

[0067] An antimicrobial heat seal coating uniformly coated on the surface, the coating comprising (A) a copolymer dispersed in a solvent, the copolymer comprising at least one selected from the group consisting of: a (meth)acrylate (co)polymer, an olefin (co)polymer, a copolymer comprising a (meth)acrylate unit and an olefin unit, and (B) an antimicrobial agent.

[0068] Embodiment 24. The food packaging article of Embodiment 23, wherein the cover comprises a material selected from the group consisting of: aluminum foil and polyethylene terephthalate.

Claims

1. An antimicrobial heat seal coating composition comprising: (A) a copolymer dispersed in a solvent comprising butyl acetate and methyl ethyl ketone, The copolymer is composed of: (i) one or more copolymers having (meth)acrylate units and (ii) one or more olefin (co)polymers, the olefin being selected from ethylene, propylene, butene and α-olefins having 5 to 20 carbon atoms; (B) an antimicrobial agent, wherein the antimicrobial agent is a silver-loaded zeolite, wherein the copolymer dispersion (A) accounts for 90 to 99.9 wt % of the total weight of the composition, and the antimicrobial agent (B) accounts for 0.1 to 10 wt % of the total weight of the composition; and (C) an antioxidant, wherein the antioxidant is octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, And (A), (B) and (C) account for 100 wt % of the antimicrobial heat seal coating composition.

2. The antimicrobial heat seal coating composition according to claim 1, wherein the copolymer dispersed in a solvent has a glass transition temperature of -60 to -30°C as measured by differential scanning calorimetry according to ISO 11357-1.

3. The antimicrobial heat seal coating composition of claim 1, wherein the antimicrobial heat seal coating composition further comprises a filler.

4. The antimicrobial heat seal coating composition of claim 1, wherein the copolymer dispersion (A) accounts for 95 to 99.9 wt% of the total weight of the composition.

5. The antimicrobial heat seal coating composition according to claim 4, wherein the antimicrobial agent (B) accounts for 0.1 to 5 wt% of the total weight of the composition.

6. A food packaging article comprising the antimicrobial heat seal coating composition according to claim 1.

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