KR20210045737A - Antimicrobial Film for Food Packaging - Google Patents

Abstract

The present invention relates to an antimicrobial film for food packaging, which is harmless to the human body while having antimicrobial properties and suppressing rancidity, and is not damaged over time. The antimicrobial film includes slaked lime derived from seashells and a thermoplastic polymer resin.

Description

Antimicrobial Film for Food Packaging {Antimicrobial Film for Food Packaging}

The present invention relates to an antimicrobial film for food packaging. More specifically, the present invention relates to an antimicrobial film for food packaging that is harmless to the human body while having antibacterial properties and an effect of suppressing rancidity, and without damage to the film itself over time.

Various methods are known as a method of imparting antimicrobial properties to food packaging films. For example, there is disclosed a food packaging film prepared by applying a coating solution including a photocatalyst, silver nanoparticles, etc. to one surface of a thermoplastic resin film and then drying/curing it. However, such antimicrobial films are not subject to the safety of their products, and there is no choice but to be limited in generalization due to the cost of raw materials.

As an alternative, products having an antimicrobial active ingredient derived from plant/animal origin are being tried. For example, an antimicrobial film prepared as a film by polymerizing catechins, which is one component of tea extract, is disclosed, and for food packaging manufactured by molding by a conventional method by containing 0.1 to 10% by weight of plant fatty acid in a synthetic resin. Antimicrobial films are disclosed. Disclosed is an antimicrobial film for food packaging prepared by including acantoic acid, perilla leaf extract and azone, natural zeolite, ocher or kaolin, and tourmaline in plastic resin raw materials. However, these still have problems of deterioration and odor of active ingredients, and compatibility with plastic materials that are the main material of the film.

Therefore, when considering these disadvantages and price together, food packaging films using mineral-derived antimicrobial agents as an active ingredient are still a viable alternative. However, there is a problem that safety is not secured because the usual mineral-derived antimicrobial substances contain harmful substances that are inevitably included, for example, harmful substances such as cadmium and lead.

Accordingly, there is a need for an antimicrobial film for food packaging that is harmless to the human body and can overcome the harmful effects of mineral-derived antimicrobial agents, even though there is no problem in generalization at a price.

Throughout this specification, other documents are referenced and citations are indicated. The disclosure contents of the cited documents are incorporated by reference in the present specification as a whole, and the level of the technical field to which the present invention belongs and the contents of the present invention are more clearly described.

Korean Patent Application Publication No. 10-2019-0094848

It is an object of the present invention to provide an antimicrobial film for food packaging that is harmless to the human body while having antibacterial properties and an effect of suppressing rancidity, and without damage to the film itself over time.

One aspect of the present invention is to provide an antimicrobial film comprising a shellfish-derived slaked lime and a thermoplastic polymer resin.

Shellfish-derived slaked lime contained in the antimicrobial film of the present invention may be obtained from one or more selected from the group consisting of scallop shells, abalone shells, conch shells, hamburger shells and sea urchin shells, but is not limited thereto.

In one embodiment of the present invention, the shellfish-derived slaked lime may be purchased and used commercially, or the slaked lime can be prepared from natural calcium sources such as scallop shells, abalone shells, conch shells, hamburger shells, sea urchin shells, etc. There may be, in detail, (i) converting the shell containing the calcium source to quicklime by crushing and sintering; And (ii) reacting the quicklime with water.

The calcium source is chemically calcium carbonate (CaCO ₃ ), which is converted into quicklime (CaO) by firing it at high temperature (for example, 800-1500℃), and then reacts the quicklime with water to The main component of slaked lime derived from the shellfish is calcium hydroxide (Ca(OH) ₂ ), and the content of the main component may vary depending on the type of shellfish or production area, preferably 80% of the main component. Or more, more preferably 85% or more, and still more preferably 90% or more.

On the other hand, in the slaked lime derived from shellfish, components other than the main component include calcium carbonate and calcium oxide as unreacted products, and other silicon dioxide, aluminum oxide, iron oxide, and magnesium oxide. Ingredient ratios and contents of ingredients other than these main ingredients may differ depending on the type of shellfish or the place of origin.

Preferably, the slaked lime derived from shellfish may be pulverized to an average particle diameter of 0.1 to 100 μm, more preferably 0.5 to 50 μm by a method such as mil-crushing. By adjusting the particle size of Sok-hee to the above-described level, uniform kneading and dispersion with the thermoplastic polymer polymer is possible. On the other hand, when the average particle diameter of slaked lime exceeds 100 µm, there is a risk of poor dispersion and poor performance, and the possibility of defective forming of a film produced therefrom increases.

The thermoplastic polymer that is kneaded with the shellfish-derived slaked lime and applicable to the antimicrobial film for food packaging of this product can be used without limitation as long as the film for food packaging is usable. For example, polyethylene such as low-density polyethylene, medium-density polyethylene, and high-density polyethylene ， Polypropylene or a copolymer thereof is widely applied to food packaging films. On the other hand, resins such as polyester (PET, etc.) nylon (PA-6, PA-66) may be applied for special applications such as vacuum packaging. In addition, other acrylic resins, ABS resins, and PLA (polylactic acid) resins may be applied. Resin, polybenzimidazole resin, polycarbonate resin, polyether sulfone resin, polyoxymethylene resin, PEEK (polyether ether ketone) resin, PEI (polyetherimide) resin, polyphenylene oxide resin, polyphenyl One or more selected from the group consisting of a ene sulfide-based resin, a polystyrene-based resin, a polyvinyl chloride-based resin, and a Teflon-based resin may be used, but the present invention is not limited thereto.

The reason why this product's food packaging film exhibits antibacterial properties seems to be due to the strong alkalinity of slaked lime. To explain with a non-limiting intention, it is understood that strong alkali components (OH) pass through the cell walls of microorganisms and hydrolyze intracellular substances, thereby having a bactericidal effect.

The term "antibacterial" in the product of the present invention means that it has an effect of inhibiting or killing the growth of bacteria. Examples of the strains that the antimicrobial film for food packaging according to the present invention exhibits antibacterial effect include, for example, Escherichia coli, Staphylococcus aureus, Salmonella, plague bacteria, Vibrio bacteria, red bacterium, Legionella, harmful acid bacteria, harmful yeast, acetate There are harmful meju fermenting bacteria, but are not limited thereto.

The advantage of the antimicrobial film according to this product is that it suppresses rancidity, that is, deterioration due to oxidation of food stored using the antibacterial film as well as antibacterial properties. Such an effect is not disclosed in the prior art, and the detailed scientific mechanism is unknown, but it seems to be related to the redox potential of calcium hydroxide.

Another advantage of using slaked lime derived from shellfish as the antimicrobial film for food packaging according to this product is that it can obtain strong alkalinity compared to mineral (limestone) derived or pure calcium hydroxide. For example, in the case of pure calcium hydroxide, it is known that the pH of the saturated calcium hydroxide solution is 12.4 at the standard condition of 25℃ and 1 atm. On the other hand, in the state of saturated solution of slaked lime derived from shellfish, higher pH is possible. For example, the product of the brand name Sigma Power (Scarro) has a basicity of 12.8 to 13.6 in a saturated solution. As such, the slaked lime of the present invention is derived from shellfish, so the pH of the slaked lime may be 12.8 to 13.6. .

Another advantage of the antimicrobial film for food packaging of the present invention is that slaked lime is not only harmless to the human body, but also little or no contamination of toxic substances to the food packaged with a film, as slaked lime is used as shellfish, that is, derived from living organisms. For example, mineral-derived slaked lime contains heavy metals such as cadmium, mercury, and chromium in addition to calcium hydroxide, which is the main component, and these components act as a contaminant for humans and food even when present in small amounts.

On the other hand, in a preferred embodiment, the slaked lime derived from shellfish of the present invention does not contain a heavy metal substantially.

The term “substantially not containing” may be completely absent from the ingredient, or may refer to containing little of the ingredient to the extent that the effect would be the same as if the ingredient was completely absent. In other words, a composition that is “substantially free of” an ingredient or element may still substantially contain such an item as long as there is no measurable effect thereof, the term “substantially not containing” is not more than 10 ppm unless otherwise indicated. , 9 ppm or less, 8 ppm or less, 7 ppm or less, 6 ppm or less, 5 ppm or less, 4 ppm or less, 3 ppm or less, 2 ppm or less, 1 ppm or less, 0.5 ppm or less, or 0.1 ppm or less.

Another advantage of the antimicrobial film for food packaging of the present invention is that the film itself has excellent preservation properties. The present inventors have found that when the mineral-derived slaked lime is kneaded with a thermoplastic polymer resin, damage to the polymer itself occurs during long-term storage, making it difficult to develop its use. It is understood that this is due to metals and/or heavy metals present as incidental components.

Such negative effects were not particularly problematic when applied to relatively thick products such as antibacterial cutting boards and electronic product housings. However, when applied to a thin sheet or film with a thickness of 0.5 mm or less, especially a product within 100 µm such as a food packaging film, the film itself is damaged over time (for example, holes, strength decrease, discoloration, etc.) There is a problem that this occurs and the function as a packaging film is lost. On the other hand, the present inventors have found that when the slaked lime derived from shellfish is used in an antimicrobial film for food packaging, for example, even in the case of a film having a thickness of 5 to 500 μm, there is no film damage over time.

In a preferred embodiment, the thickness of the antimicrobial film of the present invention may be 5 to 500 μm.

The advantage of the antimicrobial film according to the present invention is that it not only has excellent antibacterial properties as it has strong alkalinity, but also can suppress rancidity of food packaged therein. Another advantage of the antimicrobial film according to this product is that it has antibacterial properties suitable for food packaging, but does not contain heavy metals such as cadmium, mercury, and chromium, so it is not toxic to the human body or food.

The antimicrobial film of the present invention may be prepared from a composition comprising a thermoplastic polymer polymer and slaked lime derived from shellfish.

The composition comprising the thermoplastic polymer polymer and slaked lime derived from shellfish can be obtained by kneading slaked lime derived from shellfish in a state in which the polymer is melted using a kneading device known in the art, such as an extruder. On the other hand, the composition may be produced into a film by blow molding or by extruding into a sheet and then stretching.

At this time, in the composition applied to the antimicrobial film, the slaked lime derived from shellfish may be included in a ratio of 0.1 to 10 parts by weight of slaked lime derived from shellfish with respect to 100 parts by weight of the thermoplastic polymer polymer. If the content of slaked lime does not reach 0.1 parts by weight, antibacterial properties are not expressed. On the other hand, if it exceeds 10 parts by weight, it cannot be applied as a food packaging film due to its lack of transparency and strength. Also, a saturation effect occurs with respect to antimicrobial properties at about 10 parts by weight, and the content of slaked lime in the composition is further increased. Antimicrobial properties do not improve proportionally.

On the other hand, in the preparation of the composition, slaked lime derived from commercial shellfish is preferably prepared in a master batch having a slaked stone content of 20 to 70% by weight rather than a powder state, and can be kneaded with a thermoplastic polymer polymer.

The film for food packaging according to the present invention may be produced in the form of a single layer or a multilayer film. For example, in the case of vacuum packaging, polyester or nylon resin and slaked lime described above are directly blended and then formed into a film, or other resin, for example, low-density polyethylene resin is blended to form a first film. Next, a polyester or nylon-modified film may be laminated to produce an antimicrobial film for food packaging.

Meanwhile, additives commonly used in film packaging materials, for example, heat stabilizers, antioxidants, fillers, ultraviolet absorbers, colorants, etc. may be added to the composition as needed.

The antimicrobial film for food packaging of the present invention is harmless to the human body while having antibacterial properties and an effect of suppressing rancidity, and also has the effect of not damaging the film itself over time.

1 shows the results of culturing E. coli as an antimicrobial test in Examples.
Figure 2 shows the results of culturing Staphylococcus aureus as an antimicrobial test in Examples.
3 shows the results of observing the degree of spoilage of the contents over time after storing lettuce for a week as an evaluation of antibacterial activity for packaged products.
Figure 4 shows the results of observing the degree of spoilage of the contents over time after storing bread for toast for one month as an evaluation of antibacterial properties for packaged products.

Hereinafter, the present invention will be described in more detail through examples. These examples are only for describing the present invention in more detail, and it will be apparent to those of ordinary skill in the art that the scope of the present invention is not limited by these examples.

Example

1. Preparation of antibacterial film for food packaging

(1) Example 1

Slaked lime/low-density polyethylene masterbatch prepared with a content of 50% by weight of slaked lime derived from shellfish (brand name shellfish powder; average particle diameter 10 µm, particle diameter 36.3 µm or less 98 wt%, moisture content 0.2 wt%), slaked lime content of 5 wt% After blending with low-density polyethyl so as to be, an antimicrobial film for food packaging having a thickness of 10 µm was prepared by blow molding.

(2) Comparative Example 1

Food having a thickness of 10 μm in the same manner as described in Example 1, except that slaked lime derived from limestone (average particle diameter 10 μm, particle diameter 36.3 μm or less, 98% by weight, moisture content 0.2% by weight) was used instead of slaked lime derived from shellfish. An antibacterial film for packaging was prepared.

2. Heavy metal detection experiment

In order to check whether heavy metals are contained, The RoHS directive test of slaked lime derived from shellfish was performed, and the results are shown in Table 1 below.

cadmium Not detected (less than 2ppm) Mercury Not detected (less than 2ppm) chrome Not detected (less than 2ppm) Hexavalent chromium Not detected (less than 2ppm) Polybrominated biphenyl Not detected (less than 5ppm) Polybrominated diphenyl ether (10 compounds)
Polybrominated diphenyl ethers Not detected (less than 6ppm)

As shown in Table 1, it was confirmed that the antimicrobial film for food packaging according to the present invention substantially does not contain heavy metals such as mercury and cadmium, which are harmful to the human body.

3. Antibacterial test (cell culture test)

The antibacterial test was evaluated according to the method of the film compression method. ^{Specifically, Stomacher ®} 400 POLY-BAG was used as the standard film, and Staphylococcus aureus ATCC 6538P (strain 1) and Escherichia 　 coli ATCC 8739 (strain 2) was used. The test bacterial solution was incubated for 24 hours under the test condition of 35±1° C. and RH 90%, and then the number of bacteria was measured. The antibacterial effect was set to 2.0 log or more. The antimicrobial test was carried out at the FITI Test Institute located in Ochang-eup, Cheongwon-gun, Chungcheongbuk-do, and the results are shown in FIGS. 1 and 2 and summarized in Table 2 below.

From the above results, the antimicrobial film for food packaging according to the present invention is Staphylococcus aureus and Escherichia 　 coli ) showed values of 4.6 and 6.3, respectively.

4. Evaluation of antibacterial properties for packaged products

Antimicrobial evaluation of the packaging product produced using the prepared antimicrobial film was performed. For fresh food lettuce and processed food bread, the antimicrobial film prepared in Example 1 was produced in the form of a bag, and commercially purchased lettuce and bread for toast were stored as contents, and then time passed. Accordingly, the degree of decay of the contents was observed. As a control, a general low-density polyethylene film antibacterial film was used. The lettuce was photographed before and after storage for one week, and shown in FIG. 3, and the bread for toast was photographed before and after storage for one month, and the results are shown in FIG.

As a result of the experiment, it was confirmed that 　 food was packaged using the packaging product of the present invention, the packaged 　 food was kept in a fresh state for a long time by the antibacterial action of slaked lime derived from shellfish, and the 　 food 　 unique taste and quality could be maintained.

5. Evaluation of damage to the film itself after long-term storage

The antimicrobial films for food packaging prepared in Example 1 and Comparative Example 1 were allowed to stand for one month in wet conditions (room temperature, 75RH), and then the appearance was observed. In addition, under AST, D 882 conditions, the elongation is measured by a method of measuring the rate of change increased by tension in the defined mark until the film is not damaged by pulling it in the axial direction of the specimen after fixing both ends of the specimen with fixtures. Measurement and the results are shown in Table 3 below.

Exterior Elongation(%) Example 1 Transparent 10.2 Comparative Example 1 Faintly discolored 2.1

As a result of the experiment, the film of Comparative Example 1 containing limestone-derived slaked lime had a problem that as time elapsed, the film itself was damaged (discoloration, pores, decrease in strength), and the function as a packaging film was lost. On the other hand, in the antimicrobial film for food packaging of the present invention, no film damage was observed. Therefore, it was confirmed that the antimicrobial film for food packaging according to the present invention can retain its original properties excellently even when it is packaged in contact with food containing moisture.

Claims (7)

Antimicrobial film containing slaked lime derived from shellfish and a thermoplastic polymer resin. The antimicrobial film of claim 1, wherein the antimicrobial film has a thickness of 5 to 500 µm. The antimicrobial film according to claim 1, wherein the antimicrobial film is for food packaging. The method of claim 1, wherein the thermoplastic polymer resin is a polyethylene resin, a polypropylene resin, a copolymer of polyethylene and polypropylene, a polyester resin, a nylon resin, an acrylic resin, an ABS resin, a PLA (polylactic acid) system. Resin, polybenzimidazole resin, polycarbonate resin, polyether sulfone resin, polyoxymethylene resin, PEEK (polyether ether ketone) resin, PEI (polyetherimide) resin, polyphenylene oxide resin, polyphenyl Antimicrobial film, characterized in that at least one selected from the group consisting of a ene sulfide-based resin, a polystyrene-based resin, a polyvinyl chloride-based resin, and a Teflon-based resin. The antimicrobial film according to claim 1, wherein the shellfish-derived slaked lime has an average particle diameter of 0.1 to 100 µm and a pH of 12.8 to 13.6. The antimicrobial film of claim 1, wherein the slaked lime derived from shellfish does not contain a heavy metal substantially. The method of claim 1, wherein the shellfish-derived slaked lime is converted into quicklime by pulverizing and sintering the shell; And (ii) reacting the quicklime with water.

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