KR20130136305A - Polymer film for cultivating crops comprising carbon nano tubes and method of preparing the same - Google Patents

Abstract

The present invention relates to a polymer film for cultivating crops comprising nanotubes and a method for manufacturing the same and, more specifically, a polymer film for cultivating crops which has high photothermal and thermokeeping properties by having a photothermal layer in which the carbon nanotubes are dispersed in the polymer resin matrix.

Description

Technical Field [0001] The present invention relates to a polymer film for cultivating crops containing carbon nanotubes,

The present invention relates to a polymer film for cultivating crops containing carbon nanotubes and a method for producing the same, and more particularly, to a polymer film for cultivating crops having excellent light heat resistance and a method for producing the same.

Generally, crops such as field crops, flower plants, and other fruit trees are grown and supplied by vinyl houses regardless of the season. These vinyl houses are used not only in rural areas but also in the suburbs of the city, It is now one of the most common farming methods to grow crops using vinyl houses to maintain this temperature, as the crops grow and develop smoothly and can see their fruits (fruits) if they can maintain a moderate temperature.

However, additional energy consumption is essential in order to maintain the proper temperature of the greenhouse in the environmental conditions of Korea where the seasonal change is pronounced. In particular, heating and warming are absolutely necessary for the cultivation of vinyl houses in winter.

In the conventional vinyl house keeping method, a method of keeping the interior of the vinyl house warm by using a heat source such as a petroleum furnace has been used, but this method has a problem in energy efficiency.

In addition, there is a method of cultivating crops using thick and heavy nonwoven fabrics in order to increase thermal insulation in the facility. However, since they do not transmit sunlight, there is a problem that lack of photosynthesis, growth and quality deterioration are caused in crops requiring sunlight.

Therefore, it is still required to develop a material for cultivating crops that has high light transmittance and low energy consumption, but is excellent in warmth or exothermic property.

Disclosed is a polymer film for crop cultivation which is capable of controlling light transmittance and is excellent in light heat resistance, and a method for producing the same.

It is another object of the present invention to provide a polymer film for cultivating crops that can save energy in securing warmth and a method for producing the same.

1. A polymer film for cultivating crops comprising a photothermal layer in which carbon nanotubes are dispersed in a polymeric resin matrix.

2. The polymer film for cultivating crops according to claim 1, wherein the polymer resin is a resin comprising at least one polymer selected from the group consisting of polyurethane, polyacryl, polyethylene and polyester.

3. The polymer film for cultivating crops according to claim 1, wherein the carbon nanotubes are contained in an amount of 0.0001 to 10 parts by weight based on 100 parts by weight of the polymer resin based on the solid content.

4. The polymer film according to claim 1, wherein the photothermal layer is coated on at least one side of the base film.

5. The polymer film for cultivating crops according to claim 4, further comprising an adhesive layer between the light heating layer and the substrate film.

6. A vinyl house having an outer wall made of a polymer film for cultivating crops according to at least one of claims 1 to 5.

7. (S1) preparing a carbon nanotube dispersion;

(S2) preparing a mixture of the carbon nanotube dispersion and the polymer resin solution; And

(S3) coating the mixed liquid on the base film;

Wherein the method comprises the steps of:

8. The method of claim 7, wherein the carbon nanotube dispersion comprises carbon nanotubes, a dispersant, and a dispersion medium.

9. The method of claim 8, wherein the carbon nanotubes are contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the dispersion medium.

10. The method of claim 8, wherein the polymer resin solution is a resin solution containing at least one polymer selected from the group consisting of polyurethane, polyacryl, polyethylene, and polyester.

11. The method for producing a polymer film for growing crops according to claim 8, wherein the carbon nanotube dispersion and the polymer resin solution are mixed at a weight ratio of 1-10: 1.

12. The method for producing a polymer film according to claim 7, wherein the base film has an adhesive layer on at least one side.

Since the polymer film for cultivating crops of the present invention is excellent in light heat and generates heat during the presence of sunlight, when the crop is isolated from the outside, the crop can be maintained at a temperature higher than the external temperature without supplying any other energy.

When the polymer film for cultivating crops of the present invention is used as an outer film of a vinyl house, it is possible to increase the internal temperature by using sunlight, so that the energy required for raising the internal temperature can be reduced.

The present invention relates to a polymer film for cultivating crops having excellent photothermicity and warmth by providing a photothermal layer in which carbon nanotubes are dispersed in a polymer resin matrix, and a method for producing the same.

Hereinafter, the present invention will be described in more detail.

The polymer film for cultivating crops of the present invention has a light heat layer in which carbon nanotubes are dispersed in a polymer resin matrix.

When near infrared rays are irradiated, excited electrons in the carbon nanotubes are transferred to the valence band, and most of the energy generated in the carbon nanotubes is released in the form of heat (photoreactivity). The applications of carbon nanotubes using such photorefractive properties are very limited to be applied only to pharmaceuticals such as anticancer drugs.

On the other hand, as described above, cultivation of crops consumes a lot of energy for maintaining a proper temperature in some cases, which means an increase in manufacturing cost. Accordingly, the present invention overcomes the above-mentioned problems by providing a polymer film for cultivating crops having a photothermal layer containing carbon nanotubes having photoreactivity.

The polymer resin forming the polymer resin matrix of the photothermal layer according to the present invention may be used alone or as a mixture of two or more kinds of polymer resins such as polyurethane, polyacrylic, polyethylene and polyester. The dispersion stability of carbon nanotubes It is preferable to use this excellent and environmentally friendly water-based polymer, and in this respect, it is preferable to use polyurethane or polyacrylic.

In the present invention, the carbon nanotubes included in the photothermal layer may be contained in an amount of 0.0001 to 10 parts by weight based on 100 parts by weight of the polymer resin forming the matrix based on the solid content. When the content is less than 0.0001 parts by weight, the light heat effect is insignificant. When the content is more than 10 parts by weight, the permeability of the polymer film may be lowered, and the usable applications may be limited.

The light heating layer of the present invention can be coated on at least one side of the base film, that is, one side or both sides of the base film. An adhesive layer may be formed between the photothermographic layer and the base film in order to enhance the adhesion between the photothermal layer and the base film.

The adhesive layer can be formed by using an adhesive, a pressure-sensitive adhesive, a primer or the like known in the art without particular limitation, and the specific kind can be selected in consideration of the kind of the base film, the kind of the matrix resin of the photothermal layer,

The base film may be any polymer film used for crop cultivation without particular limitation, and preferably a polymer film for cultivating crops used for thermal insulation can be used. For example, a polymer film used for the outer wall of a vinyl house, a polymer film covering a furrow, and the like, but the present invention is not limited thereto. Specific examples of the base film include films made of polyalpha-olefin (PAO) such as polyethylene, ethylene vinyl acetate (EVA), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polycarbonate (PC) However, the present invention is not limited thereto.

Hereinafter, one embodiment of the method for producing a polymer film for cultivating crops of the present invention will be described in detail.

First, a carbon nanotube dispersion is prepared (S1).

Since the carbon nanotubes are highly cohesive, it is necessary to prepare the dispersion in advance in order to uniformly disperse the carbon nanotubes in the matrix of the polymeric resin. The carbon nanotube dispersion may be prepared by including carbon nanotubes, a dispersant, and a dispersion medium.

The carbon nanotubes (CNTs) may be manufactured by a conventional method such as an arc discharge method, a laser deposition method, a plasma chemical vapor deposition method, a vapor phase synthesis method, a pyrolysis method, or the like and then heat-treated. The carbon nanotubes synthesized by the above synthesis method include carbon impurities such as amorphous carbon or crystalline graphite particles and catalyst transition metal particles. For example, when manufactured by an arc discharge method, 15-30 wt% of carbon nanotubes, 45-70 wt% of carbon impurities, and 5-25 wt% of catalyst transition metal particles are contained in 100 wt% of the product. When the impregnated carbon nanotubes are directly applied to the coating solution without purification, the dispersibility and coating properties of the coating solution are deteriorated, and unique physical properties inherent to the carbon nanotubes are hardly manifested. Therefore, in the present invention, carbon nanotubes in which impurities are removed as much as possible by heat treatment of a product produced by an arc discharge method are used. Specifically, the product prepared by the above synthesis method is made into a sheet or a granule having an average diameter of 2 to 5 mm, and then the granular product is fed into a rotatable reactor inclined downward at an angle of 1-5 degrees with respect to the traveling direction , The rotary reactor is heated to 350-500 캜, and the oxidizing gas is supplied at a rate of 200-500 cc / min to 1 g of the charged product, followed by heat treatment for 60-150 minutes. At this time, the tilted rotary reactor rotates at a speed of 5-20 rpm to disperse the product, thereby maximizing the contact surface area and automatically moving in the traveling direction to maximize the contact surface area with the oxidizing gas and to prevent local oxidation Heat treated. According to this method, the weight of the charged product is reduced by 60-85%, so that high-purity carbon nanotubes are obtained.

The carbon nanotubes contain carbon impurities in an amount of not more than 40% by weight, more preferably not more than 25% by weight, in the total 100% by weight of the carbon nanotubes in terms of dispersibility and stability as well as securing the thermal conductivity of the resin composite.

The carbon nanotubes may be single-walled carbon nanotubes, double-walled carbon nanotubes, or multi-walled carbon nanotubes, which may be used alone or in combination of two or more.

It is preferable that the carbon nanotubes are contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the dispersion medium from the viewpoint of securing dispersibility.

The carbon nanotubes according to the present invention may be acid-treated or acid-treated before being incorporated into the dispersion. The acid-treated carbon nanotubes have a reactive group on their surface. Such a reactive group can further improve the binding effect with the polymeric resin matrix. Specific examples of the reactive group include a hydroxy group and a carboxy group.

The dispersant is not particularly limited as long as it is an anionic surfactant. However, it is excellent in compatibility with sodium dodecylsulfonate (SDS) or sodium dodecyl benzene sulfonate (NaDDBS) carbon nanotubes, It is preferable in terms of maximizing acidity.

As the dispersion medium, water (H ₂ O) or a lower alcohol having 1 to 5 carbon atoms can be used.

Next, a mixed solution of the carbon nanotube dispersion and the polymer resin solution is prepared (S2).

The polymer resin solution is a part forming a polymer resin matrix of the photothermal layer. As the usable polymer resin, polymer resins such as polyurethane, polyacrylic, polyethylene, and polyester may be used alone or in combination of two or more. It is preferable to use an aqueous polymer having excellent dispersion stability of nanotubes and being environmentally friendly. In this respect, it is preferable to use polyurethane or polyacrylic.

It is preferable that the polymer resin solution has a proper viscosity so as to be uniformly mixed with the carbon nanotube dispersion. In this respect, for example, the solid content may be 20 to 40% by weight, but is not limited thereto.

The mixing ratio of the carbon nanotube dispersion and the polymer resin solution is adjusted to the ratio of carbon nanotube dispersion: polymer resin solution = 1-10: 1 in consideration of the required photothermal performance, specific types of resin matrix, and binding performance of the carbon nanotubes It is preferable to mix them.

Next, the mixed solution is coated on the base film (S3).

The base film may be a polymer film used for crop cultivation without particular limitation, and preferably a polymer film for cultivating crops used for thermal insulation can be used. For example, a polymer film used for the outer wall of a vinyl house, a polymer film covering a furrow, and the like, but the present invention is not limited thereto. Specific examples of the base film include films made of polyalpha-olefin (PAO) such as polyethylene, ethylene vinyl acetate (EVA), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polycarbonate (PC) However, the present invention is not limited thereto.

The method of coating the mixed solution on the base film may be carried out by a coating method that can be used in the art such as a spraying method, a roll-to-roll coating method, a doctor blade method, an impregnation method, Can be used without.

The mixed solution may be coated on either or both surfaces of the base film.

In another aspect of the present invention, an adhesive layer may be formed on at least one surface of the base film in advance in order to improve the coating property of the mixture liquid on the base film, if necessary.

The adhesive layer can be formed by using an adhesive, a pressure-sensitive adhesive, a primer or the like known in the art without particular limitation, and the specific kind can be selected in consideration of the kind of the base film, the kind of the matrix resin of the photothermal layer,

After the base film is coated with the mixed solution, the polymer film for cultivation of the present invention can be obtained by drying at 50 to 90 ° C.

The produced polymer film for cultivating crops can be usefully used as a polymer film for thermal insulation during cultivation of crops, and can be used, for example, as an outer wall of a greenhouse or as a furrow cover.

It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to be illustrative of the invention and are not intended to limit the scope of the claims. It will be apparent to those skilled in the art that such variations and modifications are within the scope of the appended claims.

Example  One

<Preparation of Carbon Nanotube Dispersion>

A carbon nanotube (SA100, Nano Solutions, Inc.) synthesized by an arc discharge method was rotated at a rotation speed of 5-20 rpm, a temperature of 420 캜, an oxidizing gas of 250 cc / min using a rotary kiln rotary reactor having an inclination angle of 3 Treated at a feeding rate for 100 minutes to use carbon nanotubes having a carbon impurity content of 15%. 0.1 part by weight of the carbon nanotubes, 0.2 part by weight of sodium dodecylsulfonate (SDS) and 99.7 parts by weight of water were mixed and treated with an ultrasonic disperser for 60 minutes. The treated solution was centrifuged at 6,000 rpm for 20 minutes, and 90% dispersion was taken from the top, except for the impurities or macro-particles precipitated at the bottom of the vessel, to obtain a carbon nanotube dispersion.

&Lt; Production of polymer film &

The prepared carbon nanotube dispersion and a polyurethane solution (solid content: 30% by weight) were mixed at a weight ratio of 5: 1 to prepare a mixed solution.

On the other hand, a primer (HN-P420, manufactured by Hana Chemical) was coated on the surface of a polyethylene film (thickness: 0.07 mm) as a base film.

The prepared mixed solution was coated on a polyethylene film coated with a primer using a bar coater and dried at 70 ° C for 5 minutes to prepare a polymer film.

Example  2

A polymer film was prepared in the same manner as in Example 1, except that a carbon nanotube dispersion containing 0.2 parts by weight of carbon nanotubes, 0.4 part by weight of sodium dodecylsulfonate (SDS), and 99.4 parts by weight of water was used.

Example  3

A polymer film was prepared in the same manner as in Example 1, except that a carbon nanotube dispersion containing 0.05 parts by weight of carbon nanotubes, 0.1 part by weight of sodium dodecylsulfonate (SDS), and 99.85 parts by weight of water was used.

Example  4

A polymer film was prepared in the same manner as in Example 1, except that a carbon nanotube dispersion containing 0.5 parts by weight of carbon nanotubes, 1.0 part by weight of sodium dodecylsulfonate (SDS), and 98.5 parts by weight of water was used.

Comparative Example  One

A polymer film was prepared in the same manner as in Example 1, except that the polyurethane resin solution alone was used.

Test Example

The polymer films prepared in Examples and Comparative Examples were cut to a size of 10 cm x 10 cm to prepare specimens, and the following properties of the produced specimens were evaluated.

1. Measurement of permeability

For the samples prepared from Examples and Comparative Examples, the transmittance of visible light at a wavelength of 550 nm was measured using a UV spectrometer, and the results are shown in Table 1 below.

2. Photothermal  Measure

For the samples prepared from Examples and Comparative Examples, an RTD temperature sensor was attached to the top and bottom surfaces of the specimen, and the temperature was measured by irradiating sunlight for 30 minutes. The results are shown in Table 1 below.

CNT content in dispersion
(Parts by weight) Permeability (%) Surface temperature difference (final-initial)
(℃) When temperature difference
(Final - initial)
(℃) Example 1 0.1 79.2 10.4 10.5 Example 2 0.2 68.0 12.9 13.1 Example 3 0.05 82.5 8.2 7.9 Example 4 0.5 57.3 15.2 15.5 Comparative Example 1 0 83.8 5.1 4.8

Referring to Table 1, it can be seen that the embodiments having a photothermal layer have a larger temperature rise on both the top and bottom surfaces than the comparative example having no photothermal layer. In addition, the tendency that the temperature increasing effect increases as the content of the carbon nanotubes becomes larger can be grasped.

On the other hand, as the content of carbon nanotubes increases, the transmittance tends to decrease. Depending on the type of crop, some crops should have a large amount of light, and some crops may not.

From the above, it can be seen that the embodiments have a light heat layer including carbon nanotubes to control the transmittance and have excellent light heat resistance. Thus, the additional energy consumption required to raise the temperature for heating or keeping warm during crop cultivation can be reduced.

Claims (12)

A polymer film for crop cultivation, comprising a light-heat layer in which carbon nanotubes are dispersed in a polymer resin matrix.
The polymer film for crop cultivation according to claim 1, wherein the polymer resin is a resin containing at least one polymer selected from the group consisting of polyurethane, polyacryl, polyethylene, and polyester.
The polymer film of claim 1, wherein the carbon nanotubes are included in an amount of 0.0001 to 10 parts by weight based on 100 parts by weight of the polymer resin, based on solid content.
The polymer film for cultivating crops according to claim 1, wherein the photothermal layer is coated on at least one side of the base film.
5. The polymer film for cultivating crops according to claim 4, further comprising an adhesive layer between the light heat layer and the substrate film.
A vinyl house having an outer wall made of a polymer film for cultivating crops according to at least one of claims 1 to 5.
(S1) preparing a carbon nanotube dispersion;
(S2) preparing a mixture of the carbon nanotube dispersion and the polymer resin solution; And
(S3) coating the mixed solution on a base film;
Wherein the method comprises the steps of:
The method of claim 7, wherein the carbon nanotube dispersion comprises carbon nanotubes, a dispersant, and a dispersion medium.
The method of claim 8, wherein the carbon nanotubes are contained in an amount of 0.01 to 5 parts by weight based on 100 parts by weight of the dispersion medium.
The method of claim 8, wherein the polymer resin solution is a resin solution containing at least one polymer selected from the group consisting of polyurethane, polyacryl, polyethylene, and polyester.
The method of claim 8, wherein the carbon nanotube dispersion and the polymer resin solution are mixed in a weight ratio of 1-10: 1.
The method for producing a polymer film according to claim 7, wherein the base film has an adhesive layer on at least one side.