KR102030267B1 - Manufacturing method of smart window film and smart window film thereby - Google Patents

Abstract

The present invention relates to a technology for manufacturing a smart window film using a polymer dispersed liquid crystal (PDLC), in particular silver nanowire (Ag nanowire) and the surface-treated nano-carbon material By manufacturing a transparent electrode by mixing the method to omit the conventional process for fixing the silver nanowire, improve the conductivity of the transparent electrode, the smart window film manufacturing method that can improve the flexibility of the smart window and the smart window film produced by will be.
The smart window film manufacturing method of the present invention comprises the steps of: (a) applying to the first substrate using a mixed solution of a mixture of silver nanowires and the surface-treated nanocarbon material; (b) forming a first transparent electrode on the first substrate by removing a solvent included in the mixed solution; (c) repeating steps (a) and (b) to form a second transparent electrode on the second substrate; And (d) inserting and dispersing a polymer dispersed liquid crystal layer between the first transparent electrode and the second transparent electrode.

Description

Smart window film manufacturing method and a smart window film produced by the same {Manufacturing method of smart window film and smart window film thereby}

The present invention relates to a technology for manufacturing a smart window film (PDLC) using a polymer dispersed liquid crystal (PDLC), in particular silver nanowire (Ag nanowire) and the surface-treated nano-carbon material By manufacturing a transparent electrode by mixing the method to omit the conventional process for fixing the silver nanowire, improve the conductivity of the transparent electrode, the smart window film manufacturing method that can improve the flexibility of the smart window and the smart window film produced by will be.

Smart windows that can freely adjust the solar transmittance in a desired direction are divided according to the type of material used. Especially, smart windows using PDLC are easy to enlarge and have high utilization.

Smart windows with PDCL have fine liquid crystal droplets formed on the polymer matrix, and when voltage is applied, the liquid crystal droplets react and are aligned in a certain direction according to the applied electric field direction, so that the aligned direction and the direction of transmitted light coincide. It works on the principle of transmitting light.

When no voltage is applied to the smart window, the liquid crystal droplets lose their directivity and are irregularly arranged so that light does not transmit and scatter.

Smart windows can be applied to windows, mirrors, and display devices by using these characteristics, and are used for controlling light transmittance and reflectance. For example, by applying a smart window to a building or a car, when dimming is required, sunlight can be transparently adjusted to enter the room, and conversely, it can block sunlight.

As a conventional technology for using such a function has been proposed a "flexible multi-functional laminate film for smart windows" of Republic of Korea Patent No. 10-1501104, which will be described with reference to FIG.

The thermosensitive material unit 28 is a flexible multifunctional laminate for a smart window by a laminate of thermosensitive material and an electrochromic material, and a second graphene layer 24 is formed under the first flexible substrate 23.

The laminate of the thermosensitive material and the electrochromic material forms the third graphene layer 26 on the first substrate, and removes the first substrate by etching, thereby making the third graphene layer 26 flexible by the roll-to-roll method. It transfers to the base material 27.

The PDLC layer may be introduced and laminated together with the thermochromic material layer 21, the first functionalized graphene layer 22, the first flexible substrate 23, and the second graphene layer 24 to face the rollers. The flexible substrate 27 and the third graphene layer 26 are introduced into the roller portion to be laminated, and the two bodies are passed through a plurality of roller portions facing each other together with the laminated body of the PDLC layer and the non-laminated body of PDLC. Laminating produces a flexible multifunctional laminate for smart windows that includes a PLDC.

In addition to the graphene, the second and third graphene layers 24 and 26 may also use ITO, FTO, or silver nanowires, silver nanomeshes, PEDOT: PSS, or a combination thereof.

However, the transparent electrode of the conventional smart window is a combination of materials for the use of high-cost ITO and the use of silver nanowire, which requires a process for fixing the silver nanowire using a conventional expensive indium. Although comprehensively presented, it does not present any specific technical matters related to electrode material combination and electrode formation.

In addition, the related art requires a process of applying an adhesive or a process of coating an adhesive on the transparent electrode layer for adhesion of the transparent electrode, and thus, the process is somewhat complicated.

The present invention has been made to solve the problems of the prior art as described above, in the smart window manufacturing, the transparent electrode formed on both sides of the PDLC at least one side of the transparent electrode of the nano-wire and the surface-treated nano-carbon material It is an object of the present invention to make a mixture material and to bond the surface of the nano-carbon material with a chemical bond between the substrate, and to physically bond the nano-carbon material and the silver nanowire to omit the bonding process.

In addition, it is another object to provide a smart window film with a simplified manufacturing process by improving the conductivity of the transparent electrode using the mixed electrode material, and improve the flexibility of the smart window.

The object of the present invention is the step of (a) applying to the first substrate using a solution of a mixture of silver nanowires and the surface-treated nanocarbon material; (b) forming a first transparent electrode on the first substrate by removing a solvent included in the solution; (c) repeating steps (a) and (b) to form a second transparent electrode on the second substrate; And (d) inserting and dispersing a polymer dispersed liquid crystal layer between the first transparent electrode and the second transparent electrode to achieve a smart window film manufacturing method.

Therefore, the smart window film manufacturing method of the present invention and the smart window film manufactured by the present invention is a transparent electrode formed on both sides of the PDLC at least on one side of the transparent electrode formed of a mixture of silver nanowires and the surface-treated nanocarbon material It is produced and bonded through the chemical bonding of the nano-carbon material surface functional group and the substrate, there is an effect that it is possible to omit the bonding process by physically bonding the nano-carbon material and silver nanowires.

In addition, there is another effect that it is possible to provide a smart window film having a simplified manufacturing process by improving the conductivity of the transparent electrode using the mixed electrode material and improving the flexibility of the smart window.

1 is a cross-sectional view schematically showing a flexible multifunctional laminate according to the prior art,
2 is a flowchart showing a smart window manufacturing method according to the present invention;
3 is an electron micrograph of an embodiment of the present invention and a comparative example
4 is a light transmission efficiency characteristic diagram of Examples and Comparative Examples of the present invention.

The terms or words used in this specification and claims are not to be construed as being limited to their ordinary or dictionary meanings, and the inventors may appropriately define the concept of terms in order to best describe their invention. It should be interpreted as meaning and concept corresponding to the technical idea of the present invention based on the principle that the present invention.

Therefore, the embodiments described in the specification and the drawings shown in the drawings are only the most preferred embodiment of the present invention and do not represent all of the technical idea of the present invention, various modifications that can be replaced at the time of the present application It should be understood that there may be equivalents and variations.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a flowchart illustrating a smart window manufacturing method according to the present invention. As shown in Figure 2, using a mixed solution of a mixture of silver nanowires and the surface-treated nano-carbon material applied to the first substrate (steps S1 to S4), by removing the solvent contained in the mixed solution Forming the first transparent electrode on the first substrate (steps S5 and S6), repeating steps S1 to S5 during the process of forming the first transparent electrode on the first substrate to form the second transparent electrode on the second substrate And inserting the polymer dispersed liquid crystal layer between the first transparent electrode and the second transparent electrode and laminating (S8 and S9).

Here, the surface-treated nano-carbon material may be selected from the group consisting of carbon nanotubes, carbon black, carbon nanofibers, graphene, nano activated carbon fibers and mixtures thereof, the surface treatment is ozone containing oxygen and air, By any one of carbon dioxide and carbon monoxide oxidation process, liquid acid oxidation process using acid, electrical oxidation process, non-oxidation process, plasma treatment process, electrical polymerization process, vapor phase growth process and coating process Is performed (step S2).

The surface-treated nanocarbon material prepared as described above was prepared in a 10 to 80 weight ratio of the surface-treated nanocarbon material compared to the silver nanowires contained in the silver nanowire solution in order to prepare a mixed solution of silver nanowires and the surface-treated nanocarbon material. Add. After stirring for 10 minutes to 3 hours at 30 to 90 ℃ for uniform dispersion of the added nano-carbon material is subjected to ultrasonic treatment for 10 to 30 minutes (step S3).

Here, when the addition ratio of the surface-treated nanocarbon material is less than 10 weight ratio, there is a disadvantage in that the conductivity and adhesive properties are poor, and when mixing to exceed 80 weight ratio, the resistance due to the aggregation of the surface-treated nanocarbon material increases Since there is a disadvantage of falling transparency and the surface-treated nano carbon material addition ratio is to maintain a 10 to 80 weight ratio.

The mixed solution prepared to have such a weight ratio is applied to the surface of the first substrate (step S4), and this application process is performed by any one of spraying, brush painting, dip coating, thin film coating and spin coating.

Thereafter, the formation of the first transparent electrode is performed by inducing bonding and dispersing by applying heat for 10 to 30 minutes at 30 to 160 ° C to chemically bond the functionalities of the surface-treated nanocarbon material and the first substrate included in the applied mixed solution. It is formed by evaporating the solvent of the solution (step S5).

Here, when the process temperature and time is less than the lower limit, the solvent contained in the mixed solution is not evaporated, and a phenomenon in which a chemical bond is not formed between the surface-treated nanocarbon material and the first substrate is generated, and also the process temperature And when the time exceeds the upper limit, deformation occurs due to heat of the first substrate.

After the first transparent electrode is formed on the first substrate, the second transparent electrode is formed on the second substrate in the same process (steps S1 to S5 and S7), and the polymer is formed between the first transparent electrode and the second transparent electrode. The smart window film is manufactured by inserting and dispersing the dispersed liquid crystal layer (steps S8 and S9).

Here, the lamination of the first and second substrates and the polymer dispersed liquid crystal layer is performed in a roll to roll manner, and the first substrate, the second substrate, and the polymer are laminated using hot air and ultraviolet rays. The dispersed liquid crystal layer is cured.

Example

An embodiment of the present invention is to manufacture a smart window film using a nanowire and the surface-treated nano-carbon material as a transparent electrode.

In the embodiment of the present invention, carbon nanotubes were used as the nano carbon material, and the surface functional groups of the carbon nanotubes were prepared by mixing nitric acid and sulfuric acid. Carbon nanotubes were added to 250 ml of a solution in which nitric acid and sulfuric acid were mixed at a 3: 1 ratio, and then ultrasonicated for 1 hour. After sonication, the carbon nanotubes were filtered, washed with distilled water, and dried at 80 ° C. for 12 hours to introduce carboxyl groups into the carbon nanotubes, thereby treating the carbon nanotubes.

Subsequently, the surface-treated carbon nanotubes were added to the silver nanowire solution, stirred at 60 ° C. for 1 hour, and sonicated for 30 minutes to prepare a mixed solution in which the silver nanowires and the surface-treated carbon nanotubes were mixed.

Thereafter, the mixed solution was evenly applied to the surface of the PET film as a substrate by spraying, the PET film coated with the mixed solution was heat treated at 150 ° C. for 2 hours to remove the used solvent, and the functional group of the carbon nanotubes PET was induced to bind.

After the two transparent electrodes were formed in the same manner, a smart window film was manufactured by laminating a polymer dispersed liquid crystal layer between the films using a roll-to-roll method.

Comparative Example 1)

In Comparative Example 1, a smart window film using a silver nanowire and an untreated surface carbon nanomaterial was manufactured.

Here, the smart window film was manufactured in the same manner as in the embodiment, except that the carbon nanomaterial was not surface treated, unlike in the embodiment of the present invention.

Comparative Example 2)

In Comparative Example 2, a smart window film using only silver nanowires as a transparent electrode was manufactured.

Comparative Example 2 was prepared in the same procedure as in Example 1, except that the nano-carbon material surface-treated in Example 1 of the present invention to produce a smart window film.

Hereinafter, the shape characteristic evaluation of the transparent electrode and the light transmission efficiency evaluation of the transparent electrode according to the properties of the material used for the transparent electrode will be described.

3 is an electron micrograph of an embodiment of the present invention and comparative examples, (a) is an embodiment of the present invention, (b) and (c) is an electron micrograph of Comparative Examples 1 and 2.

Here, in the embodiment of the present invention, the transparent electrode is formed in a state where the silver nanowires and the surface-treated nanocarbon material are uniformly dispersed, and in the case of Comparative Example 1, the silver nanowires and the untreated surface of the nanocarbon material It can be estimated that the aggregation shows a relatively low light transmission efficiency compared to the embodiment of the present invention.

However, Comparative Example 2 in which a transparent electrode was formed using only silver nanowires may be estimated to have a relatively high light transmission efficiency due to less generation of agglomerates than Examples, but an additional process for fixing silver nanowires is required. In the embodiment of the present invention, the surface-treated nanocarbon material shown in the lower right portion plays a role of fixing the silver nanowires so that an additional process for fixing the silver nanowires can be omitted.

Therefore, the embodiment of the present invention may have a slightly lower light transmission efficiency than Comparative Example 1, but the transparent electrode is made of a mixture of silver nanowires and the surface-treated nanocarbon material, the surface functional group and the substrate of the nanocarbon material It can be expected that even if the bonding through the chemical bonding, and the physical bonding of the nano-carbon material and silver nanowire to omit the bonding process, the function can be implemented.

4 is an evaluation of the light transmission efficiency of the Examples and Comparative Examples of the present invention.

As shown in FIG. 4, the light transmission efficiency showed high values in the order of Comparative Example 2, Example, and Comparative Example 1. FIG.

Comparative Example 2 exhibited a light transmission efficiency of 80 to 90% up to a wavelength of 470 nm, and then showed a light transmission efficiency of 90% or more at a wavelength of 480 to 600 nm, and a light transmission of 88 to 90% at 610 to 740 nm. Efficiency was shown.

In the case of the embodiment of the present invention, although the light transmission efficiency is about 1% higher than that of Comparative Example 2 up to 400 nm, the light transmission efficiency is relatively lower than that of Comparative Example 2 at a wavelength of 410 nm or more, but light transmission is less than 2% There was only a decrease in efficiency.

Through this, the present invention by forming a transparent electrode made of a mixture of silver nanowires and the surface-treated nanocarbon material, fixing the silver nanowires while minimizing the light transmission efficiency compared to forming a transparent electrode only with conventional silver nanowires The fixing step of the silver nanowires by the organic binder can be omitted.

Although the present invention has been shown and described with reference to the preferred embodiments as described above, it is not limited to the above embodiments and those skilled in the art without departing from the spirit of the present invention. Various changes and modifications will be possible.

Claims (11)

(a) applying a silver nanowire and a surface-treated nanocarbon material to a first substrate using a mixed solution;
(b) forming a first transparent electrode on the first substrate by removing a solvent included in the mixed solution;
(c) repeating steps (a) and (b) to form a second transparent electrode on the second substrate; And
(d) inserting and polymerizing a polymer dispersed liquid crystal layer between the first transparent electrode and the second transparent electrode;
In the step (a), the mixed solution is prepared by dispersing after adding the surface-treated nanocarbon material to a silver nanowire solution, and the mixed solution is compared with silver nanowires contained in the silver nanowire solution. The surface-treated nano carbon material is added to have a weight ratio of 10 to 80,
In the step (b), the first transparent electrode is formed by applying heat for 10 to 30 minutes at 30 to 160 ° C. such that the functional group of the nanocarbon material and the first substrate are chemically bonded to induce binding and the solvent of the mixed solution. Smart window film manufacturing method characterized in that formed by evaporation.
The method of claim 1,
The surface-treated nano-carbon material is a smart window film manufacturing method, characterized in that selected from the group consisting of carbon nanotubes, carbon black, carbon nanofibers, graphene, nano activated carbon fibers and mixtures thereof.
The method of claim 1,
The surface treatment may be performed by any one of ozone, carbon dioxide and carbon monoxide including oxygen and air. Smart window film manufacturing method, characterized in that carried out by any one of a vapor phase growth process and a coating process.
delete delete The method of claim 1,
The surface-treated nanocarbon material is added to the silver nanowire solution and then stirred at 30 to 90 ° C. for 10 minutes to 3 hours, followed by ultrasonication for 10 to 30 minutes, characterized in that the mixed solution is prepared. Smart window film manufacturing method.
The method of claim 1,
Smart window film manufacturing method characterized in that the coating of the mixed solution in step (a) is carried out by any one of spray, brush painting, dip coating, thin film coating and spin coating.
delete The method of claim 1,
Smart window film manufacturing method characterized in that in the step (d) the lamination of the first and second substrate and the polymer dispersed liquid crystal layer is carried out in a roll to roll (Roll To Roll) method.
The method of claim 9,
Smart window film manufacturing method characterized in that for curing the first substrate, the second substrate and the polymer dispersed liquid crystal layer laminated using hot air and ultraviolet rays in step (d).
A smart window film manufactured by the smart window film manufacturing method of any one of claims 1 to 3, 6, 7, 9, and 10.

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