KR20190070071A - Agricultural packaging film containing graphene - Google Patents

Abstract

The present invention is to provide a packaging film for crops by processing a resin composition containing graphene. The present inventors have dispersed graphene in an epoxy resin and processed a pellet, obtained by melt mixing the resin in low-density polyethylene using an extrusion apparatus, into a film which can be used as a packaging material for the storage of bananas and large green onions. As a result, it has been confirmed that the progress of discoloration and decay of the crops was remarkably slowed down, and thus the present invention has been completed.

Description

{AGRICULTURAL PACKAGING FILM CONTAINING GRAPHENE}

The present invention is intended to provide a packaging film for a crop by processing a resin composition containing graphene. Besides the general use of physical packaging, the composition of the packaging film is a special function of its own, and has the effect of preventing the development of discoloration and decay of crops such as vegetables and fruits during distribution and storage.

Crop packaging films are used to prevent crop damage during distribution and storage of crops. Recently, besides simple physical packaging function, there is a demand for a technology that can preserve the quality of the crop for a long time.

It is a common practice to incorporate various additives into the matrix resin for the expression of these functions. Examples of the additive include preservatives, nanomaterials, far-infrared ray emitting materials, and the like.

Preservatives among the above additives are not constantly controversial about harmfulness to the human body and have a bad influence on the taste and flavor inherent to the food. Therefore, it is required to develop a technique that can replace preservatives at present.

An example of using a resin composition in which a nano material is complexed as a packaging film is disclosed in Patent Publication No. 10-2016-0113699. The above data discloses a method of reducing the entry and exit of oxygen through a packaging film by using a resin composition containing 0.1 to 20 weight percent of a nano-clay.

An example of using a resin composition containing a far-infrared ray emitting material as a packaging film is disclosed in Registration Practice Publication No. 20-0390396. A method for maintaining the freshness of a crop by the emission of far-infrared rays is disclosed by using a resin composition containing a powder of a far-infrared ray emitting material such as silica and alumina.

However, when the last two types of methods are used, the transparency of the packaging film due to the addition of the nanoclay or ceramic powder may be lowered, and development of a technique for overcoming this problem is required.

KR 10-2016-0113699 A (2016.09.30) KR 20-0390396 Y1 (2005.07.11)

In order to solve the above-described problems of the prior art, the present invention provides a film for packing crops by reducing oxygen outflow through a film and forming a composite material with a resin capable of emitting far-infrared rays, To thereby minimize the decrease in transparency of the substrate.

We fabricated the film by melt - extrusion of graphene with resin, packaged vegetables and fruits, and observed the appearance of the crops over time. As a result, it was confirmed that discoloration and decay of the crops packed with the graphene-containing film were remarkably delayed as compared with the control film not containing graphene, and the inventors completed the invention.

The graphene-containing film produced according to the present invention was packed in a sealed state with the banana and sawdust, and then discolored and decayed with time while being left at room temperature. Banana samples packaged with a control film without graphene showed significant discoloration and decay of the skin after 14 days at room temperature, but in the case of graphene-containing films, the discoloration was partially Only corruption did not start. Similar results were obtained from the results of experiments on the big waves under the same test conditions. This is because, in the case of a film containing graphene, ultraviolet light transmission is effectively blocked and oxygen passage is suppressed, thereby suppressing the oxidation of plant cells and further increasing the emission of far-infrared rays from the film to actively maintain the metabolism of cells It is thought that the result of discoloration and corruption is delayed.

1 is a transmission electron microscope image of graphene prepared according to Example 1. Fig.

The present invention provides a film for packaging agricultural crops containing graphene and a method for producing the same.

The graphene includes graphene produced by a CVD method or a physical stripping method, graphene oxide (GO) produced by a chemical stripping method, and reduced graphene oxide (rGO) produced by reducing the graphene oxide can do.

Hereinafter, the present invention will be described in detail.

Examples of graphenes that can be used in the present invention include graphene and graphene oxide which are produced mechanically or chemically by peeling graphite in a top-down manner, or reduced graphene obtained by reducing the graphene oxide Oxide. In addition, as another example of graphene that can be used in the present invention, a carbon-containing material such as graphite or a hydrocarbon compound is used as a raw material and is produced in a bottom-up manner by chemical vapor deposition Graphene can be heard.

Generally, the graphene or graphene oxide obtained in a top-down manner has a chemical structure with mainly a multi-layered carbon layer, and the graphene obtained in a bottom-up manner has a chemical structure close to that of a carbon single layer. When a special synthesis process of a large area graphene is excluded, the lateral size of the graphene obtained by the above two methods can be widely distributed from several tens nm to several tens of microns.

In order to reduce the average thickness (represented by the number of carbon layers) of the graphene synthesized by the above method and the average plane size, the graphene raw material is dispersed in a dispersion solvent and then subjected to ultrasonic treatment or ball mill treatment, And the subsequent classification process can be used.

The preferred size of graphene as an additive for the resin composition provided in the production of packaging films for crops is an average thickness of 1 to 20 carbon layers and an average lateral size of 0.02 to 20 탆. When the average thickness of the graphene layer is 20 carbon layers or more, the transmittance of the visible light is greatly reduced and a transparent packaging state can not be obtained. Also, when the average plane size of the graphene is 20 m or more, the dispersion of the graphene in the polymer matrix into the nano level becomes difficult, and the effect of suppressing the oxygen permeation can be reduced. On the other hand, in the case of producing graphene having an average plane size of 0.02 mu m or less, economical efficiency may be a problem as an additional process such as a classification process is added.

In addition, it is also well known that the surface of the graphene can be chemically treated to functionally function as a graphene surface. Examples of such techniques include oxidation of graphene surface using nitric acid and sulfuric acid, reduction of graphene surface through reaction with reducing agent, alkylamidation of graphene surface by reaction with alkylamine, and reaction with alkyl alcohol And the like.

In the present invention, graphene can be provided in a composite state at a nano level to polyethylene, polypropylene, or PET resin, which is commonly used as a base resin of a packaging film for a crop. For this purpose, a resin composition in which graphene is complexed can be prepared by mixing graphene with a liquid epoxy resin, dispersing the mixture with ultrasonic waves, and mixing the resultant mixture with the resin using a common extruder. It is preferable that the composition is adjusted within a range of 0.01 to 1.0 part by weight based on 100 parts by weight of the resin. When the content of graphene is less than 0.01 part by weight, the freshness preservation effect of grapefruit may be insignificant. When the graphene content is more than 1.0 part by weight, the transparency of visible light is lowered and the economical burden due to the price of graphene may increase.

In the present invention, it is believed that when a film formed of the graphene composite resin composition is used as a film for packing crops, graphene can contribute to maintaining the freshness of the crop by the following functional group.

First, the antioxidant function of crops by reducing the oxygen permeability of the composite film with graphene can be mentioned. When a film is produced by using a composition in which nanoparticles such as nano-clay or graphene are combined with a resin, the nanoparticles are oriented in a horizontal direction on the film surface to form a small particle such as oxygen, nitrogen, carbon dioxide, It is well known that the rate at which gas molecules permeate the film is remarkably reduced. As a result, in the case of the packaging film according to the present invention, oxygen and steam are prevented from entering and exiting, thereby preventing the oxidation of the crop and contributing to the maintenance of the freshness of the crop.

Second, the effect of reducing the ultraviolet transmittance of the composite film of graphene can be mentioned. Graphene has the property of absorbing electromagnetic waves in the ultraviolet A and B regions. It is well known that, even in the case of harvested crops, the freshness of storage and distribution can be maintained for a long period of time when the oxidation of plant cells is prevented and the metabolism thereof is activated. In other words, as the graphene-containing film blocks ultraviolet rays, oxidation of plant cells due to ultraviolet rays is prevented to maintain the activity of the cells, thereby contributing to maintaining the freshness of the packaged crops.

Finally, there is a far-infrared emission effect of graphene. Since graphene forms a strong absorption band in the ultraviolet and far infrared region, the graphenes present in the packing film are packaged in a manner such as vibrational relaxation after ultraviolet absorption and resonant light scattering in the far infrared region It is possible to increase the energy density of the far-infrared rays which are trapped in the contents. That is, when the energy density of the far-infrared rays applied to the packaged fruits or vegetables is increased, it is possible to contribute to maintaining the freshness of the packaged crops by increasing the activity of the body fluids in the plant cells and the activity of the enzyme action.

Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited by these examples.

Example 1: Preparation of 'graphene dispersion aqueous solution' and its dry powder

200 g of graphene powder purchased from Nano Reader Co., Ltd. was placed in 1800 g of purified water, and ultrasonic waves were added thereto for 6 hours while mechanically stirring. Then, the mixture was charged into a ball mill together with zirconia beads having a size of about 10 탆, And then filtered to prepare a graphene dispersion aqueous solution having a solid content of 10.0% by weight.

The graphene dispersion aqueous solution was adsorbed on the substrate, dried, and analyzed by transmission electron microscope (TEM). As a result, it was confirmed that the plane size of graphene was in the range of 0.02 to 20 μm. 1 shows a part of an image obtained by the electron microscope analysis. As a result of analyzing the sample with atomic force microscope (AFM), it was confirmed that the plane thickness of graphene was distributed in the range of 1 to 20 atom layers.

Next, the 'graphene dispersion aqueous solution' was dried in a vacuum oven at 60 ° C. for 24 hours to obtain a 'graphene powder'.

Example 2: Preparation of 'graphene resin pellets'

100 g of the 'graphene powder' obtained in Example 1 was mixed with 300 g of an epoxy resin (YD-128, Kukdo Chemical Co., Ltd.), and the mixture was heated and stirred at 60 ° C for 6 hours. The entire amount of the graphene / epoxy mixture thus obtained was put into a Benbury mixer in which 9.6 kg of LDPE had been preliminarily mixed and sufficiently mixed at 160 캜 and then processed through an extruder to obtain a 'graphene composite resin composition' in the form of pellets.

Example 3: Manufacture of a 'graphene composite resin film'

The pellets obtained in Example 2 were processed by a conventional blow molding molding apparatus to obtain a film having a thickness of 50 탆. Hereinafter, the film is referred to as A film.

Comparative Example 1: Production of general molding film

Using LDPE pellets not containing graphene, a film having a thickness of 50 mu m was obtained in the same manner as in Example 3. [ Hereinafter, the film is referred to as a B film.

Example 4: Optical characteristics analysis of 'Graphene composite resin film'

UV / VIS spectra and FTIR spectra of the film A were measured. According to UV / VIS spectral results, the film A showed a light absorption rate of 60% in the ultraviolet region of 400 nm wavelength or less. Further, according to the results of the FTIR spectra, it was confirmed that the A film had absorption bands of 60% and 80% of light absorption rates near 10 탆 and 20 탆, respectively, corresponding to the far infrared region.

Example 5: Analysis test of the freshness maintenance effect of 'graphene composite resin film'

Banana was peeled into the film A and the film B and left at room temperature in a sealed state. The appearance of the banana was observed on the first day, seven days, and fourteen days after the experiment.

In addition, the green wave was adjusted to a length of 10 cm, and then the film was inserted into the A film and the B film, sealed, and the appearance thereof was observed over time.

In the case of banana, the brownish spots were partially formed in the bark when wrapped in B film after 7 days, and most of the bark changed to brown at 14 days and it was confirmed that the decay was considerably advanced . On the other hand, the banana wrapped in film A had no change in its appearance after 7 days, and at 14 days, only partial brownish spots appeared on the skin and corruption was not observed .

In the case of Dae - pa, it was confirmed that corruption began to take place partly after 7 days when it was wrapped in B film, and that corruption had progressed considerably at the end of 14 days. On the contrary, after 7 days, there was no change in the appearance of the packaged A strips and 14 days later, it was confirmed that the corruption proceeded only partially.

Claims (3)

100 parts by weight of resin and 0.01-1.0 parts by weight of graphene.
The film for wrapping a crop according to claim 1, wherein the graphene has an average thickness of 1 to 20 atomic layers and an average plane size of 0.02 to 20 탆.
The film for wrapping a crop according to claim 1, wherein the resin is one selected from the group consisting of polyethylene, polypropylene and polyethylene terephthalate (PET).

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