Antimicrobial Film Having Nano ZnO Particle Method of Making the Same and Food Packing Products

Antimicrobial Film Having Nano ZnO Particle, Method of Making the Same and Food Packing Products

The present invention relates to an antibacterial film, a manufacturing method thereof, and a food packaging product using the same, and more particularly, to an antibacterial film containing nano zinc oxide, a manufacturing method thereof, and a food packaging product using the same.

With the development of industry, the demand for films using synthetic resins is rapidly increasing, and they are used in many areas of daily life. In addition. There is an increasing demand for films with functionality other than general films, and recently, as interest in health increases, products with antibacterial properties that are resistant to bacteria and bacteria have been developed and released.

In the case of food packaging materials, since food has a close relationship with health, the packaging material must also be one that does not elute components harmful to the human body, and it is required that the internal food covered with the packaging material can be stored for a long time without deterioration as much as possible.

To change food, it is possible to think of spoilage, which is mainly caused by biological factors, and simple deterioration, which is mainly caused by chemical factors, but since they can have mutual influence, there is a limit to strictly distinguishing these factors.

In general, as one of the representative methods to prevent simple deterioration, it is a method to seal food with food packaging material, prevent decay or deterioration due to biological factors, and prevent bacteria from passing through food packaging material, and bacteria that have already entered the food rapidly multiply Methods to prevent it can be used. If an antibacterial film containing an antibacterial material is used for food packaging, it also inhibits the passage of bacteria on one side and can also have the effect of inhibiting the proliferation of bacteria in the internal food in contact with the antibacterial film. has been and is being used.

Recently, products using various antibacterial agents have been released. Although organic antibacterial agents are widely used as antibacterial agents, there is a movement to refrain from using organic antibacterial agents due to increased resistance and harmfulness to the human body due to their basic characteristics. Inorganic antibacterial agents and natural antibacterial agents are used to replace organic antibacterial agents, but natural antibacterial agents have a problem in that the unit price is high and the antibacterial power is expressed only when the amount added is large, and the antibacterial durability is also reduced. In the case of inorganic antibacterial agents, antibacterial durability is good, but there is a problem of harm to the human body.

For example, due to the discovery of the antibacterial properties of silver nanoparticles, antibacterial synthetic resin products containing silver nanoparticles have been released in various fields. Recently, as the harmfulness of silver nano to the human body has become a problem, the silver nano craze has blown in home appliances, etc. and then suddenly disappeared.

Accordingly, by fusion of nanotechnology with inorganic antibacterial agents with good antibacterial durability, antibacterial agents that have good antibacterial power and are harmless to the human body are being developed.

<p><patcit num="0001"><text>Korean Patent Registration No. 10-1334283 </text></patcit><patcit num="0002"><text>Korean Patent Publication No. 10-2018-0071601 </text></patcit></p>

<p>The present invention is to overcome the above-mentioned existing antibacterial film, food packaging material using the same, and manufacturing limitations thereof, and it is harmless to the human body and realizes excellent antibacterial power even with a small amount of an antibacterial film that can be economically and technologically competitive; An object of the present invention is to provide a manufacturing method thereof and a food packaging product using the same.</p>

<p>The antibacterial film of the present invention for achieving the above object includes 0.05% by weight to 0.5% by weight of nano zinc oxide having an average particle diameter of 1 to 50 nm by mass. In addition, the purity of the nano zinc oxide is 99.9% or more.</p><p>In particular, in the present invention, a plurality having a high concentration synthetic resin layer containing nano zinc oxide at a high concentration and a low concentration synthetic resin layer containing no or low concentration of nano zinc oxide to increase the antibacterial efficiency while reducing the content of nano zinc oxide The high-concentration synthetic resin layer may include 0.05 wt% or more and 0.5 wt% or less of nano-zinc oxide, and the low-concentration synthetic resin layer may include 0 wt% or more and 0.1 wt% or less of nano-zinc oxide. It is configured such that the content of nano zinc oxide in the synthetic resin layer is higher than that of the nano zinc oxide in the low concentration synthetic resin layer. </p><p>The antibacterial film manufacturing method of the present invention for achieving the above object is characterized in that in manufacturing the antibacterial film of the present invention, a multilayer film blow method by co-extrusion of a high-concentration synthetic resin raw material and a low-concentration synthetic resin raw material is characterized.</p><p>In the present invention, the multilayer film constituting the antibacterial film may be a three-layer film such that a high-concentration synthetic resin layer is positioned on the outer layer, or may simply consist of two layers, or may consist of only a high-concentration synthetic resin layer as one layer. In order to increase the nano-zinc oxide concentration of the high-concentration synthetic resin layer, it is preferable to be formed thinner than the low-concentration synthetic resin layer.</p><p>In the present invention, when the multilayer film is formed in two layers, the multilayer film is formed by co-extruding the inner film and the outer film in a multilayer film blow method, expanding and spreading with a roller, cutting both ends in the width direction, and the inner layer film overlaps It can be made by separating the center into two two-layer films using an interlayer slitter.</p><p>In the present invention, in the production of a high-concentration synthetic resin layer, a raw resin and a high-concentration masterbatch may be mixed and used, and a relatively low-concentration masterbatch itself may be used without mixing. Nano zinc oxide has good dispersibility when added in the form of a master batch (including 10 wt% to 30 wt% based on mass), and 0.05 wt% to 0.5 wt% based on mass is mixed with the resin in the form of one particle nano zinc oxide can also be used.</p><p>In the present invention, when producing a film by a co-extrusion blow method, the process can be carried out by supplying a release material to the inside of the cylinder made of the synthetic resin layer inside, and the two separated when the center is separated in a state in which the film is spread through the roller. You can simply pull the part in different directions, or at the same time use a method to easily divide the center of the multilayer film using an interlayer slitter.</p><p>The food packaging product of the present invention may be made by processing the antibacterial film of the present invention, and may include various types such as zipper bags, roll bags, sanitary bags, sanitary gloves, and wraps.</p>

<p>According to the present invention, there is no problem of harm to the human body by manufacturing and supplying an antibacterial film using nano zinc oxide, which is known to be harmless to the human body, and an antibacterial film that can be economically and technologically competitive by realizing excellent antibacterial power even with a small amount of addition and food packaging products based on it.</p><p>According to the method of the present invention, it is possible to efficiently manufacture and supply the antibacterial film of the present invention. </p>

1, 2a and 2b are conceptual cross-sectional views showing the layer structure of a multilayer antibacterial film according to an embodiment of the present invention; 3a to 3d are process cross-sectional views schematically illustrating intermediate steps of the method of the invention; 4 is a table showing one of the results of an antibacterial test and an antifungal test conducted while varying the nano zinc oxide content; Figure 5 is a photograph comparing before and after the test in which the antibacterial film of the present invention is applied to Staphylococcus aureus-resistant bacteria in the FITI Test Research Institute antibacterial test; 6 and 7 are photographs comparing before and after the test in which the antibacterial film of the present invention is applied to each strain in the antibacterial test and the antifungal test of the KOTITI Research Institute. Figure 8 is an exemplary view of the test report of SGS (SGS) food container adhesion. 9 is an exemplary view of the test result of SGS (SGS) bisphenol A (BPA) content. 10 is a photograph for explaining a food packaging product manufactured using the antibacterial film of the present invention.

Hereinafter, the present invention will be described in more detail through specific examples of the present invention with reference to the drawings.

1, 2A and 2B are cross-sectional views showing the layer configuration of the antibacterial film of the present invention.

In FIG. 1, the antibacterial film 10 has a three-layer structure, and the relatively thick layer 11 in the middle is a low-concentration synthetic resin layer and is a synthetic resin layer with a thickness of 40 micrometers (mic) made of polyethylene that does not contain nano-zinc oxide at all. , the thin layer 13 on both outer surfaces is a synthetic resin layer with a thickness of about 10 micrometers made of polyethylene containing 0.06 wt% of nano zinc oxide as a high-concentration synthetic resin layer.

In this case, if calculated as the total antibacterial film, it can be seen as an antibacterial film having about 0.02 wt% of nano zinc oxide based on mass. In this case, nano zinc oxide is used with a particle size of 1 to 50 nm and a purity of 99.9%.

Nano zinc oxide with such a particle size has been known to be harmless to the human body through various experiments. In addition, nano zinc oxide is known to have effects such as blocking ultraviolet rays, delaying resin deterioration, and deodorizing when used in a synthetic resin film.

As raw materials for synthetic resins that are the base of antibacterial films, polyolefin-based synthetic resins such as polyethylene (LDPE, LLDPE, HDPE, MDPE) or polypropylene (PP), polyethylene terephthalate (PET), ethylene vinyl acetate (EVA), polyvinyl chloride ( PVC) or polyamide (PA).

In Figure 2a, the antibacterial film 20 has a simple two-layer structure, and the relatively thick layer 21 is a synthetic resin layer with a thickness of 50 micrometers (mic) made of polyethylene that does not contain nano-zinc oxide as a low-concentration synthetic resin layer. , the remaining thin layer 23 is a synthetic resin layer with a thickness of 10 mic made of polyethylene containing 0.063 wt% of nano zinc oxide as a high-concentration synthetic resin layer.

Even in this case, when calculated as the total antibacterial film, it can be seen as an antibacterial film having about 0.01 wt% of nano zinc oxide based on the mass. In this case, nano zinc oxide is used with a particle diameter of 1 to 50 nm and a purity of 99.9% or more.

Referring to FIG. 2B , the antibacterial film 30 may have a simple one-layer structure, and as a thick high-concentration synthetic resin layer 31, in particular, as a synthetic resin layer made of polyethylene containing nano-zinc oxide, nano-zinc oxide is 0.06% by weight. It may be a synthetic resin layer with a thickness of 60 mic included.

Even in this case, when calculated as the total antibacterial film, it can be seen as an antibacterial film having approximately 0.06 wt% of nano zinc oxide based on the mass. In this case, nano zinc oxide is used with a particle size of 1 to 50 nm and a purity of 99.9% or more.

3a to 3d are process cross-sectional views schematically and conceptually illustrating a method of manufacturing the multilayer antibacterial film as described above by the co-extrusion blow method.

Figure 3a shows a front cross-section in which the outer high-concentration synthetic resin material molten layer 13' and the inner low-concentration synthetic resin material melt layer 11' are extruded together in a concentric circle through co-extrusion in a synthetic resin film extruder jig.

In the blow method, the extruder jig blows high-temperature air into the empty space in the middle to expand the synthetic resin material forming a concentric circle before it hardens, thereby increasing the width of the synthetic resin film made by this method.

FIG. 3B shows the steps of flattening two concentric circles made to have an approximately constant diameter through FIG. 3A to form a multilayer film. At this time, the co-extruded result in the form of two concentric circles may have a shape as shown in FIG. 3B while passing between the rollers.

Since the middle layer 11 in which the two layers are integrated is the same material, in a state where the inner concentric circles are not solidified, they adhere to each other under pressure while passing through the rollers and can be recognized as one layer. The thin layers 13 on both sides of the middle layer 11 form separate layers that are connected to each other at both ends in the width direction but are substantially spaced apart from each other.

If the antibacterial film to be made has a layer structure as shown in FIG. 1, the multilayer film is sufficiently hardened in this state, and it is wound on a storage roll and stored.

FIG. 3C shows a state in which both sides in the width direction connecting the upper and lower layers are removed with a slitter or the like as a next step additionally passed to make a simple two-layer film as shown in FIG. 2 . In the step of Figure 3c, the low-concentration synthetic resin material layer forming a small concentric circle is sufficiently cooled and the surface is sufficiently hardened so that the inner two layers do not adhere well to each other even when passing between the rollers.

3D is an antibacterial effect of the two-layer state of the upper and lower two layers by separating the upper and lower two-layered states by separating the upper and lower layers while pulling the upper and lower layers separately after removing both ends of the multilayer film 20 in the width direction as shown in FIG. 3C , as shown in FIG. 3C . It is a side view showing the state in which the film 20 is made.

Here, the multilayer film is separated from each other by pulling the upper and lower layers separately, as well as installing an interlayer slitter between the upper and lower layers so that even if the original two layers constituting the central layer are weakly attached to each other, the interlayer slitter ( 40) so that the separation can be achieved well.

On the other hand, in order to make a high-concentration synthetic resin material molten layer for the film extruder, a base synthetic resin material and nano zinc oxide must be prepared. It is convenient to use a masterbatch that is hardened by uniformly mixing fine zinc powder and a small amount of base synthetic resin.

Therefore, in the extruder, the pellets of the base synthetic resin component and the master batch pellets are precisely supplied in the weight ratio according to the calculated content, mixed in the film extruder through heating and stirring, and extruded through the extruder jig under appropriate temperature and pressure conditions.

In the present invention, the multilayer antibacterial film of three or more layers may be used to impart various functionalities. In order to impart functionality, a functional material may be included in at least one of several layers. The functional material may be included in the form of an additive. In this case, as a form of adding the additive, it is used in the form of a masterbatch or powder by mixing the base resin with the additive and, if necessary, ZnO.

As additives, antistatic agents, dispersants, antioxidants, UV stabilizers, heat stabilizers, flame retardants, repellents, anti-fouling agents, fillers, reinforcing agents, plasticizers, colorants, impact-resisting agents, crosslinking agents, optical brighteners, anti-blocking agents, slip agents, etc. are widely used. , classified according to the use, there are slip agents, antiblocking agents, dispersants, plasticizers, fillers, antistatic agents, etc. for improving workability. There are flame retardants, repellents, antifouling agents, antioxidants, biodegradants, etc. to provide product functionality, and for realizing product properties, antioxidants, UV stabilizers, heat stabilizers, antistatic agents, colorants, pigments, dyes, optical brighteners, reinforcing agents, shock-resistance, etc.

Even in the case of the food packaging product closely related to the antimicrobial film of the present invention, additives may be added to increase its use or workability. For example, for packaging work efficiency, a slip agent is used to improve when a problem occurs during work, an anti-blocking agent is added when blocking occurs, and a dispersant is prescribed when the dispersion is not good to make the work better.

Recently, as a functional product, biodegradable substances are added so that they can be decomposed after use, an antioxidant is added to improve long-term storage, and an antifogging agent is added to prevent fogging in many cases to make the product more visible.

In some cases, additives are used to realize desired physical properties, such as prescribing a colorant when a color is required for the required physical properties of a product, or adding an ultraviolet (UV) stabilizer if the product is vulnerable to UV or the contents are sensitive to UV.

The content of the additives as described above can be variously adjusted according to the material properties and the use of the film to be made, and a weight ratio of 0.1 to 10% is usually suitable. If it is too large, it may cause problems in production and processability as a film, and if it is too small, it becomes difficult to realize the functionality that is the purpose of adding the additive.

The thickness of the antibacterial film can be manufactured differently depending on the purpose, but it is usually manufactured in a range of 10 mic to 150 mic.

Looking more closely at the manufacturing method of this embodiment, for the convenience of controlling the content, a masterbatch is used instead of a nano zinc oxide powder, and a co-extrusion dry blow or blown (BLOWN) method is used in an extruder for film extrusion.

First, the nano zinc oxide masterbatch and synthetic resin raw material (Base Resin) pellets according to the use of the product to be made are put into the mixing space in the extruder, and mixed and transferred by heating. As the nano zinc oxide content of the masterbatch, 10 to 30% is suitable, and 10 wt% of the nano zinc oxide content is used here.

When each synthetic resin material of high concentration and low concentration is sufficiently kneaded with the synthetic resin raw material and reaches a temperature of 150°C to 300°C, which is an appropriate temperature for extrusion, blow extrusion is performed through a co-extrusion jig. Blow speed is usually 300 ~ 2000RPM, here the work was done at 600 ~ 1000RPM. Antibacterial films of various thicknesses were produced by controlling conditions such as extrusion jig temperature, blow speed, and air pressure.

The antibacterial film thus produced is processed by each processor to produce food packaging products (zipper bag 54, roll bag 51, sanitary bag 55, sanitary glove 53, wrap 52) as shown in Table 1 below. did. At this time, there were no problems with the product, such as workability, transmittance, and sealing part adhesion.

<tables num="1"><table><tgroup cols="4"><colspec colnum="1" align="center" colname="col1" colwidth="1075" /><colspec colnum="2" align="center" colname="col2" colwidth="3629" /><colspec colnum="3" align="center" colname="col3" colwidth="2669" /><colspec colnum="4" align="center" colname="col4" colwidth="3500" /><tbody><row><entry align="center" colname="col1">product</entry><entry align="center" colname="col2">SPEC</entry><entry align="center" colname="col3">Machinability (workability)</entry><entry align="center" colname="col4">Checklist</entry></row><row><entry align="center" colname="col1">zipper bag</entry><entry align="justify" colname="col2">SIZE: Width 25cm(30cm)*Length 30cm Thickness: 60micro/mic Zipper (double color zipper) Material: LDPE NanoZnO content: 6000PPM (0.06%)</entry><entry align="center" colname="col3">Good (no issues)</entry><entry align="center" colname="col4">There is no significant change in the permeability due to the use of a small amount. No problem when sealing.</entry></row><row><entry align="center" colname="col1">rollback</entry><entry align="justify" colname="col2">SIZE: Width 25cm(35cm)*Length 35cm Thickness: 15~20mic Material: HDPE NanoZnO Content: 6000PPM(0.06%)</entry><entry align="center" colname="col3">Good (no issues)</entry><entry align="center" colname="col4">No problem when sealing</entry></row><row><entry align="center" colname="col1">plastic bag</entry><entry align="justify" colname="col2">SIZE: Width 25cm*Length 35cm Thickness: 10~15mic *M-shaped Material: HDPE NanoZnO Content: 6000PPM (0.06%)</entry><entry align="center" colname="col3">Good (no issues)</entry><entry align="center" colname="col4">No problem when sealing</entry></row><row><entry align="center" colname="col1">vinyl gloves</entry><entry align="justify" colname="col2">SIZE: Width 22.5cm*Length 27.5cm Thickness: 27~28mic Material: LDPE NanoZnO content: 6000PPM (0.06%)</entry><entry align="center" colname="col3">Good (no issues)</entry><entry align="center" colname="col4">No problem when sealing</entry></row><row><entry align="center" colname="col1">lab</entry><entry align="justify" colname="col2">NanoZnO content: 6000PPM (0.06%)</entry><entry align="center" colname="col3">Good (no issues)</entry><entry align="center" colname="col4">No big change in permeability due to small amount use</entry></row></tbody></tgroup></table></tables>

On the other hand, as a result of antibacterial evaluation for each antibacterial film sample obtained by varying the content by the manufacturing method as described above, results such as the table of FIG. 4 and the photos of FIGS. 5 to 9 were obtained.

It can be seen that even though the content of 0.05% to 0.5%, which is lower than the content normally used in the past, is applied, there is an antibacterial effect without a problem in using the product. In the antibacterial test of FIG. 4, JIS Z 2801 film adhesion method, Escherichia coil ATCC 2692 for E. coli strain, Staphylococcus aureus ATCC 6538 for Staphylococcus aureus strain, and Klebsiella pneumoniae ATCC 4352 for Staphylococcus aureus strain. showed a decrease. Chaetomium globosum was used as the fungus in the ASTM G21 anti-mildew test for the antifungal test of FIG. 4 , and the fungus did not grow at any content.

5 is a photograph comparing before and after the test of the 0.06% antibacterial film of the present invention using MRSA Staphylococcus aureus ATCC33591 as a strain of Staphylococcus aureus-resistant bacteria by the ASTM E2149 shake flask method in the FITI Test Research Institute antibacterial test. , 99.9% of antibacterial activity was recorded.

6 is an Escherichia coil ATCC 2692, Staphylococcus aureus ATCC 6538, Staphylococcus aureus ATCC 6538, and Klebsiella pneumoniae ATCC 4352 for the Escherichia coil ATCC 2692 by ASTM E2149 shake flask method in the KOTITI antibacterial test. It is a photograph comparing before and after the test of 0.06% antibacterial film, and the experimental result recorded 99.9% of antibacterial activity in all cases.

7 is a photograph comparing before and after the test of the 0.06% antibacterial film of the present invention, using Chaetomium globosum as the fungus of the ASTM G21 anti-mildew test in the antifungal test of the KOTITI Test Research Institute, and it was found that the fungus did not grow.

8 is a report of SGS (SGS) food container adhesion test, and showed results suitable for all standards required by the Ministry of Food and Drug Safety.

9 is a test result of SGS (SGS) bisphenol A (BPA) content, and shows ND (not found) results. It can be viewed as BPA-free.

10 illustrates food packaging products manufactured using the developed antibacterial film, that is, a zipper bag 54 , a roll bag 51 , a sanitary bag 55 , a sanitary glove 53 , and a wrap 52 .

From the above results, in the case of other antibacterial agents such as organic antibacterial agents in manufacturing by applying nano zinc oxide to the antibacterial film, there is a problem in that the antimicrobial activity occurs at the high temperature of extrusion processing. Because it maintains antibacterial activity in the state of nanoparticles, extrusion processing and film production were possible.

It was confirmed that there was no difficulty in manufacturing the film by adding a small amount, and in the case of the prepared antibacterial film, excellent results were obtained in antibacterial and antifungal tests. And, in manufacturing the film for food packaging, processability and transparency were good, so it was good for food packaging, and the film surface condition was also very good.

In the above, the present invention has been described with reference to the limited embodiments, but these are only illustratively described to help the understanding of the present invention, and the present invention is not limited to these specific embodiments. Accordingly, those of ordinary skill in the art to which the present invention pertains will be able to make various changes or application examples based on the present invention, and it is natural that such modifications or application examples belong to the appended claims.

10, 20, 30: antibacterial film 40: interlayer slitter