KR102547207B1 - Reverse-operating smart window film, manufacturing method thereof and smart window including the same - Google Patents

Abstract

The present invention relates to a reverse driving smart window film, a method for manufacturing the same, and a smart window including the same. Specifically, it is transparent when voltage is not applied, opacity increases as voltage is applied, and has low emission characteristics, A reverse driving smart window film capable of being easily applied to windows and achieving a high haze even with a thin thickness, a method for manufacturing the same, and a smart window including the same.

Description

Reverse-operating smart window film, manufacturing method thereof and smart window including the same {Reverse-operating smart window film, manufacturing method thereof and smart window including the same}

The present invention relates to a reverse driving smart window film, a method for manufacturing the same, and a smart window including the same. Specifically, it is transparent when voltage is not applied, opacity increases as voltage is applied, and has low emission characteristics, The present invention relates to a reverse drive smart window film that can be easily applied to windows and doors even with a thin thickness and can achieve excellent opacity, a method for manufacturing the same, and a smart window including the same.

Recently, as interest in resource depletion and quality of life increases, energy saving effect, eco-friendliness and convenience are important topics. Attention is being paid to smart window technology that simultaneously satisfies these factors.

In general, a smart window is formed to be turned on and off, and refers to a window in which the amount of light or heat passing through is controlled by changing the transmittance of light when a voltage is applied. That is, the smart window is provided to be changed into a transparent, opaque or semi-transparent state by voltage, and is also called variable transmittance glass, dimming glass, or smart glass.

In addition, smart windows can be used as partitions of indoor spaces or as skylights placed in openings of buildings, and can also be used as highway signs, bulletin boards, scoreboards, clocks, or advertising screens, and can be used as automobiles, buses, aircraft, It can also be used as windows or sunroofs on ships or trains.

A typical example of such a smart window is a polymer dispersed liquid crystal-based smart window.

Polymer dispersed liquid crystal (PDLC)-based smart window is in the form of liquid crystal droplets dispersed in a polymer binder. In case (On state), the refractive index of the dispersed liquid crystal changes and the refractive index of the two materials matches, so it means a smart window that looks transparent.

On the other hand, in applying smart window technology, as interest in the environment and energy has recently increased, the demand for energy-saving industrial products has increased. That is, a glass or film effective in reducing heat load from sunlight is required. In general, the cause of more than 35% of building energy loss is the window performance of the building, and when the window performance deteriorates, the cooling, heating and air conditioning efficiency of the building may also decrease.

In addition, smart windows can also function as privacy protection in that they are glass that can adjust the transmittance. In the case of conventional smart windows, they are impermeable when power is not supplied, and transmit only when power is applied. Since it is glass, power must always be supplied in order to use it as a transparent window, so there is a problem in that power efficiency deteriorates. Accordingly, there is a demand for smart windows that operate in the reverse direction so that power can be supplied only when necessary for privacy protection when used on windows or internal glass walls.

Therefore, there is an urgent need to develop a smart window film having low solar heat gain and emissivity, which can reduce cooling and/or heating costs as well as improve power efficiency.

Registered Patent Publication No. 10-2154513 (2020.09.10.)

The present invention has been made to solve the above-mentioned problems, and the problem to be solved by the present invention is that the change in transmittance according to whether or not voltage is applied occurs in the reverse direction, so that power for use as glass with high transmittance is unnecessary and excellent even with a thin thickness. An object of the present invention is to provide a film for a reverse driving smart window capable of achieving opacity and excellent durability, a smart window including the same, and a method for manufacturing the film.

In order to solve the above problems, the present invention is a low-emission (low-E) film unit comprising a first metal oxide layer, a reflective metal layer and a second metal oxide layer sequentially; and

a first electrode layer sequentially in contact with one surface of the low-emissivity film unit; a liquid crystal unit including a liquid crystal having negative dielectric constant anisotropy; And a second electrode layer; a liquid crystal film unit including a; including,

Provided is a reverse drive smart window film that satisfies the following conditional expression 1).

1) T _on < T _off

In Conditional Expression 1), T _on represents the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when a voltage of 80V is applied between the first electrode layer and the second electrode layer, and T _off is It shows the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when no voltage is applied.

In a preferred embodiment of the present invention, the liquid crystal unit may sequentially include a first alignment layer, a liquid crystal layer, and a second alignment layer.

Here, the first alignment layer and the second alignment layer may include a polyimide-based polymer, and may each independently have a thickness of 100 to 300 nm.

In a preferred embodiment of the present invention, the reverse driving smart window film may further satisfy Conditional Expressions 2) and 3) below.

2) 6 ≤ T _off /T _on ≤ 30

3) 3% ≤ T _on ≤ 15%

In Conditional Expressions 2) and 3), T _off represents the light transmittance (%) of the reverse driving smart window film when no voltage is applied, and T _on represents the voltage of 80V between the first electrode and the second electrode. It represents the light transmittance (%) of the reverse driving smart window film when voltage is applied.

In a preferred embodiment of the present invention, the liquid crystal layer includes a cured product of a liquid crystal ink including a liquid crystal and a polymer resin,

The liquid crystal may have a dielectric constant anisotropy (Δε) of -6.0 to -1.0 and a refractive index anisotropy (Δn) of 0.07 to 0.15.

In a preferred embodiment of the present invention,

The liquid crystal is a bicyclohexyl-based compound, a cyclohexylphenyl-based compound, a cyclohexene-based compound, a cyclohexylcarboxylic acid ester-based compound, a difluorine phenylene ( phenylene), a bicyclo hydrocarbon compound, and at least one selected from a tricyclo hydrocarbon compound,

The polymer resin may include one or more oligomers selected from aromatic urethane acrylate oligomers, aliphatic urethane acrylate oligomers, and polyester acrylate oligomers; and at least one monomer selected from acrylate-based monomers, epoxy-based monomers, and siloxane-based monomers; As formed by polymerization of one or more of, it may have a viscosity of 800 to 1500 cPs.

In a preferred embodiment of the present invention, the liquid crystal ink may include the liquid crystal and the polymer resin in a weight ratio of 30:70 to 55:45.

In a preferred embodiment of the present invention, the first electrode layer and the second electrode layer each independently include at least one selected from indium tin oxide (ITO) and a conductive polymer, and each independently has a sheet resistance of 30 It may be ~200Ω/□.

In a preferred embodiment of the present invention, the reflective metal layer includes a silver-palladium-copper alloy (Ag-Pd-Cu alloy, APC), and the first metal oxide layer and the second metal oxide layer are each independently It may include zinc tin oxide (ZTO) containing 25 to 45 wt% of zinc oxide (ZnO) and 55 to 75 wt% of tin oxide (SnO ₂ ).

In a preferred embodiment of the present invention, the low-emissivity film part further includes a transparent protective layer and a low-emission film base layer, and the liquid crystal film part further includes a liquid crystal film base layer, each layer comprising a liquid crystal film base layer, A first electrode layer, a liquid crystal unit, a second electrode layer, a low-emission film substrate layer, a first metal oxide layer, a reflective metal layer, and a second metal oxide layer may be provided in this order.

In a preferred embodiment of the present invention, the reverse drive smart window film may have a total thickness of 50 to 200 μm, and a thickness ratio between the low-emission film part and the liquid crystal film part may be 1:1 to 2.5.

In a preferred embodiment of the present invention, the adhesion of the liquid crystal layer to the alignment layer measured according to the following measurement method may be 10 to 100 gf/inch.

[measurement method]

The first alignment layer and the second alignment layer of the reverse-driving smart window film are separated by 180 degrees at a speed of 10 mm/min, and the adhesion of the liquid crystal layer to the alignment layer is measured.

The present invention also provides a first film unit in which a first electrode layer and a first alignment layer are sequentially formed on one surface of a liquid crystal film base layer; and a first step of preparing a second film unit in which a second electrode layer and a second alignment layer are sequentially formed on one surface of the low-emissivity film base layer; and

The first alignment film of the first film part and the second alignment film of the second film part face each other, and liquid crystal ink containing liquid crystal having a negative dielectric anisotropy is introduced between the first alignment film and the second alignment film, and then laminated and cured. A second step of obtaining a smart window film by forming a liquid crystal layer between the first alignment layer and the second alignment layer;

The smart window film provides a method for manufacturing a reverse driving smart window film, characterized in that it satisfies the following Conditional Expression 1).

1) T _on < T _off

In Conditional Expression 1), T _on represents the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when a voltage of 80V is applied between the first electrode layer and the second electrode layer, and T _off is It shows the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when no voltage is applied.

In a preferred embodiment of the present invention, the second film unit sequentially forms a first metal oxide layer, a reflective metal layer, and a second metal oxide layer on one surface of the low-emissivity film base layer, and the low-emissivity film base layer It may be manufactured by sequentially forming the second electrode layer and the second alignment layer on the other surface of the layer.

In a preferred embodiment of the present invention, curing in the second step may be UV curing.

In a preferred embodiment of the present invention, in the second step, curing may be performed by irradiating ultraviolet rays having an intensity of 1 to 10 mW/cm ² for 1000 to 5000 seconds.

The present invention also, windows and doors; and the reverse driving smart window film provided on at least one surface of the window or door.

Unlike conventional smart windows, the present invention can be made opaque by applying voltage, so it is driven in the reverse direction, and excellent opacity can be achieved even with a thin thickness, and at the same time, the adhesion between each layer of the smart window film is excellent, and the process is also It is simple and has excellent productivity, and has the advantage of excellent efficiency in reducing cooling and heating costs due to low solar heat acquisition and emissivity.

FIG. 1A schematically illustrates the principle of light transmission or non-transmission when a voltage is applied to a PDLC liquid crystal film and when a voltage is not applied.
FIG. 1B is a picture taken when a voltage is applied to a smart window to which a PDLC liquid crystal film is applied and when a voltage is not applied, respectively.
FIG. 2A schematically illustrates the principle of light transmission or non-transmission when a voltage is applied or not applied to a smart window film including a PNLC liquid crystal film according to a preferred embodiment of the present invention.
FIG. 2B is a photograph taken when a voltage is applied or not applied to a smart window to which a smart window film is attached according to a preferred embodiment of the present invention.
3 is a diagram schematically showing a layer structure of a reverse driving smart window film according to a preferred embodiment of the present invention.
4 is a diagram schematically illustrating a method of performing a coating process of an alignment layer during a manufacturing process of a reverse driving smart window film according to a preferred embodiment of the present invention.
5 is a diagram schematically illustrating a method of performing a lamination and curing process during a manufacturing process of a reverse driving smart window according to a preferred embodiment of the present invention.

Hereinafter, the configuration and effects of the present invention will be described in more detail with reference to the accompanying drawings.

A smart window film containing PDLC liquid crystal, which has been conventionally used as a smart window film, is a polymer dispersed liquid crystal (PDLC)-based smart window film in which liquid crystal is dispersed in a polymer binder, and is semi-permeable (with haze) in the absence of an electric field. It was a film whose transparency increased in the presence of an electric field. This is advantageous for privacy protection because the effect of transmitting light, which is the function of windows, can be exhibited only when an electric field is applied, but there is a disadvantage that power must be continuously supplied to obtain transparency.

Therefore, in the present invention, this problem was solved by developing a reverse driving smart window film that is transparent when an electric field does not exist, but can increase opacity by applying an electric field, and also reduces cooling and heating costs by combining with a low-emission film. At the same time, it is possible to provide a smart window film that can be achieved.

That is, the present invention sequentially includes a first metal oxide layer, a reflective metal layer, and a low-E film unit including a second metal oxide layer; and

a first electrode layer sequentially in contact with one surface of the low-emissivity film unit; a liquid crystal unit including a liquid crystal having negative dielectric constant anisotropy; And a second electrode layer; a liquid crystal film unit including a; including,

Provided is a reverse drive smart window film that satisfies the following conditional expression 1).

1) T _on < T _off

In Conditional Expression 1), T _on represents the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when a voltage of 80V is applied between the first electrode layer and the second electrode layer, and T _off is It shows the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when no voltage is applied.

In a preferred embodiment of the present invention, the reverse driving smart window film may further satisfy Conditional Expressions 2) and 3) below.

2) 6 ≤ T _off /T _on ≤ 30

3) 3% ≤ T _on ≤ 15%

In Conditional Expressions 2) and 3), T _off represents the light transmittance (%) of the reverse driving smart window film when no voltage is applied, and T _on represents the voltage of 80V between the first electrode and the second electrode. It represents the light transmittance (%) of the reverse driving smart window film when voltage is applied.

By having such light transmission characteristics, the reverse driving smart window film according to the present invention has clear transparency when voltage is not applied, but has excellent insulation performance, and provides a smart window film having excellent privacy protection effect by applying voltage. there will be

Accordingly, the present invention is transparent when voltage is not applied, but excellent cooling and heating cost reduction efficiency can be obtained by the low-emission film part, and when voltage is applied, transparency can be lowered to obtain the effect of privacy protection. A smart window can be provided.

According to a preferred embodiment of the present invention, the liquid crystal film unit may further include a liquid crystal film base layer, and more preferably may further include an adhesive layer.

In addition, according to a preferred embodiment of the present invention, the low-emissivity film unit may further include a low-emissivity film base layer, and more preferably may further include a protective film layer.

3 is a diagram schematically showing the layer structure of a reverse driving smart window film according to a preferred embodiment of the present invention.

Referring to FIG. 3 , the reverse driving smart window film 1000 according to a preferred embodiment of the present invention includes a low-emissivity film unit 100 and a liquid crystal film unit 200, and the low-emissivity film unit 100 ) may include the low-emission film base layer 110 in contact with the liquid crystal film unit 200, and sequentially formed on the opposite side of the liquid crystal film unit 200 among both sides of the low-emissivity film base layer 110. A first metal oxide layer 120, a reflective metal layer 130, and a second metal oxide layer 120' are formed, and a protective film layer 140 may be included on the second metal oxide layer 120'.

In addition, the liquid crystal film unit 200 may include a liquid crystal film base layer 210, and the liquid crystal unit 230 is formed on the liquid crystal film base layer 210 by the first electrode layer 220 formed on one surface thereof. and coupled to the reflective film unit 100 by the second electrode layer 220' formed on the other surface of the liquid crystal unit 230.

The liquid crystal unit 230 may include a liquid crystal layer 232 and a first alignment layer 231 and a second alignment layer 231' formed on both sides of the liquid crystal layer.

According to a preferred embodiment of the present invention, the reverse drive smart window film may have a total thickness of 50 to 200 μm, which is thinner than conventional smart window films. By having such a thin thickness, construction costs can be saved, and nevertheless, the difference in transmittance between voltage applied and non-applied states is remarkable, so that shielding characteristics as a smart window can be excellently implemented.

Preferably, the reverse driving smart window film may have a thickness of 80 to 180 μm, more preferably 100 to 170 μm, and most preferably 120 to 150 μm. If the thickness of the reverse driving smart window film is less than 50 μm, it may be impossible to manufacture the product due to thermal deformation during manufacturing of the double-sided substrate. In addition, as the thickness further decreases, there may be a problem in that shielding characteristics and interlayer adhesion when voltage is applied deteriorate.

In addition, if the thickness of the reverse driving smart window film exceeds 200 μm, construction time and cost increase, and transmittance decreases when no voltage is applied, resulting in poor transparency.

In addition, in a preferred embodiment of the present invention, the low-emissivity film part and the liquid crystal film part may have a thickness ratio of 1:1 to 1:2.5. More preferably, it may have a thickness ratio of 1:1.5 to 1:2.0, more preferably 1:1.6 to 1:1.8.

If the thickness ratio is less than 1:1 (that is, if the thickness of the low-emissivity film part is greater), there may be a problem of thermal deformation in the sputtering process of forming the electrode layer of the low-emissivity film base layer and the liquid crystal film part of the low-emissivity film part. If the ratio exceeds 1:2.5 (i.e., the thickness of the liquid crystal film part is significantly thicker), the difference in tension between the low-emissivity film part and the liquid crystal film part during smart window film manufacturing increases the rate of defects in the process, such as tearing. there is a problem.

Hereinafter, each layer of the smart window film of the present invention will be described.

1. Low-emissivity film part

In general, low-emissivity film or low-e film used for windows and doors is a film that allows visible light or near-infrared rays to pass through, but blocks rays with long wavelengths of mid-infrared to far-infrared rays from passing through.

In addition to controlling the transparency of the smart window film, the low-emission film (low-e film) unit of the present invention can reduce the solar heat gain (SHGC) and emissivity of the smart window to which the smart window film is applied, When applied to windows, it can show the effect of reducing indoor heating and cooling costs. Since the smart window film according to the present invention has high transmittance when voltage is not applied, excellent solar heat gain (SHGC) and emissivity reduction are possible by combining with the low-emissivity film unit 100.

In addition, due to the presence of the low-emissivity film unit 100, there are advantages in that color difference change in weather resistance can be reduced and durability, heat insulation performance and strength can be increased.

The low-emissivity film unit 100 preferably includes a low-emissivity film base layer 110, a first metal oxide layer 120, a reflective metal layer 130, a second metal oxide layer 120 'and a protective film layer ( 140) may be sequentially formed, and the first metal oxide layer 120, the reflective metal layer 130, and the second metal oxide layer 120' may be formed by a deposition process, such as sputtering, chemical vapor deposition, or atomic layer deposition ( ALD) and the like. Preferably, it may be formed by a sputtering process.

1) Low-emissivity film base layer

The low-emissivity film unit 100 according to a preferred embodiment of the present invention may include a base layer 110. The low-emissivity film base layer 110 serves as a support layer for the low-emissivity film unit 100 and serves as a substrate on which other layers of the low-emissivity film unit 100 can be formed, thereby facilitating the process. to provide.

The base layer 110 may include any material commonly used in the art without limitation, and preferably may include at least one selected from glass and polyethylene terephthalate (PET), more preferably plasma or It may include a corona surface treated PET film. When there is a process involving a roll during the lamination process, it is preferable to use a flexible PET film as a substrate rather than a glass substrate.

The low-emissivity film base layer 110 may have a thickness of 10 to 80 μm, preferably a thickness of 20 to 60 μm, and more preferably a thickness of 40 to 55 μm.

If the thickness is less than 10㎛, in manufacturing the smart window film, deformation of the substrate due to heat generated during drying and curing may occur, and tension applied to the substrate during the roll-to-roll process may cause Tearing problems can occur. In addition, when the thickness exceeds 80 μm, the cost of raw materials increases, and the length that can be wound on one roll is shortened, resulting in an increase in process time, such as an increase in roll replacement time.

2) metal oxide layer

Next, the low-emissivity film unit 100 according to a preferred embodiment of the present invention includes metal oxide layers 120 and 120'. The metal oxide layers are formed on both sides of the reflective metal layer 130, respectively. In this specification, for convenience, the side closer to the liquid crystal film unit 200 is the first metal oxide layer 120, and the oxide layer on the opposite side is the second metal oxide layer. It is called an oxide layer 120'.

The first metal oxide layer 120 and the second metal oxide layer 120' exhibit excellent emissivity maintenance durability, transmittance, and heat insulation performance, prevent color difference change in weather resistance, and protect the reflective metal layer 30, respectively. As performing, any metal oxide commonly used in the art may be included without limitation, but preferably zinc tin oxide (ZTO) may be included.

The first metal oxide layer 120 and the second metal oxide layer 120' preferably each independently contain 25 to 45% by weight of zinc oxide (ZnO) based on the total weight, and tin oxide (SnO ₂ ) It may include zinc tin oxide containing 55 to 75% by weight.

If the content of zinc oxide (ZnO) is less than 25% by weight and the content of tin oxide (SnO2) exceeds 75% by weight, the durability of the metal oxide layer may be reduced, and the content of zinc oxide is less than 45% by weight. When the content of tin oxide (SnO 2 ) is less than 55% by weight, the heat insulating performance of the low-emissivity film unit 100 may be deteriorated.

In addition, according to a preferred embodiment of the present invention, the first metal oxide layer 120 and the second metal oxide layer 120 'are each independently 10 to 50 nm, preferably 20 to 40 nm, more preferably It may have a thickness of 25 to 35 nm.

If the thickness is less than 10 nm, the protection effect for the reflective metal layer 130 described later may decrease, emissivity and weatherability color difference may increase, and durability of the reverse driving smart window film 1000 of the present invention may deteriorate. , when the thickness exceeds 50 nm, the heat insulation performance may deteriorate due to the increase in emissivity.

3) reflective metal layer

The reflective metal layer 130 included in the low-emissivity film unit 100 of the present invention is a layer capable of transmitting visible light (which may also include near-infrared rays) and reflecting electromagnetic waves having long wavelengths of mid-infrared to far-infrared rays. The material may include any material that can be commonly used for a reflective metal layer in the art without limitation, and preferably may include a silver-palladium-copper alloy (Ag-Pd-Cu alloy, APC).

In addition, the reflective metal layer 130 may have a thickness of 10 to 20 nm, preferably 12 to 18 nm, and more preferably 13.5 to 16.5 nm.

If the thickness of the reflective metal layer is less than 10 nm, the thermal insulation performance may deteriorate and the solar heat gain may increase. If the thickness exceeds 20 nm, the transmittance of visible light decreases and the reflectance of the reverse driving smart window film according to the present invention is significantly There may be issues with escalation.

According to a preferred embodiment of the present invention, the first metal oxide layer 120, the reflective metal layer 130, and the second metal oxide layer 120' may satisfy all of the following conditions A) and conditions B).

Condition A)

condition B)

, 더욱 바람직하게는

일 수 있고, 조건 B)는 바람직하게는

, 더욱 바람직하게는

일 수 있다.The above condition A) is preferably

, more preferably

can be, and condition B) is preferably

, more preferably

can be

In conditions A) and B), a is the thickness of the first metal oxide layer 120, b is the thickness of the second metal oxide layer 20', and c is the thickness of the reflective metal layer 130.

This means that when the thickness of the reflective metal layer 130 is thin, the thermal insulation performance may not be good, and the solar heat gain rate may be increased, which may cause a problem in that the indoor temperature rises. because it can rise. In addition, when the thickness of the first and second metal oxide layers 120 and 120' is thin, the reflective metal layer 30 may not be protected and durability may be deteriorated. There may be issues with deterioration.

Therefore, the first metal oxide layer 120, the reflective metal layer 130, and the second metal oxide layer 120', which may be included in the reverse driving smart window film of the present invention, should have appropriate thicknesses, and condition A) and condition B) is satisfied, and the aforementioned problems can be solved.

이면, 역방향 구동 스마트 윈도우 필름의 내구성 및 단열 성능이 좋지 않을 수 있고, 방사율 및 내후성이 색차변화가 증가할 수 있으며, 태양열 차단 성능이 저하되어 태양열 취득율이 상승하는 문제가 있을 수 있다. 또한, 만일 상기 조건 B)에서

이면, 역방향 구동 스마트 윈도우 필름의 내구성이 저하될 수 있고, 내후성 색차변화가 증가할 수 있으며, 가시광선 투과율이 낮아지고 스마트 윈도우 필름의 반사율이 현저히 높아질 수 있다.If, in the above condition A)

If this is the case, durability and heat insulation performance of the reverse driving smart window film may be poor, emissivity and weather resistance may increase in color difference, and solar heat blocking performance may deteriorate, resulting in an increase in solar heat gain. Also, if the above condition B)

If this is the case, durability of the reverse driving smart window film may decrease, weatherability color difference change may increase, visible light transmittance may decrease, and reflectance of the smart window film may significantly increase.

4) protective film layer

According to a preferred embodiment of the present invention, the low-emissivity film unit 100 may further include a protective film layer 140. The protective film layer 140 is formed on the second metal oxide layer 120' and is formed at the outermost part of the smart window film, and serves to protect the reverse driving smart window film of the present invention. In particular, it serves to protect the first metal oxide layer 120, the reflective metal layer 130, and the second metal oxide layer 120'.

In addition, the protective film layer 140 can perform a function of remarkably improving the emissivity maintenance durability of the low-emissivity film unit 100, and its thickness is preferably 0.5 to 2.5 μm, preferably 0.8 to 2.0 μm. It may have a thickness of, more preferably may have a thickness of 1.0 ~ 1.5㎛.

If the thickness of the protective film layer 140 is less than 0.5 μm, the emissivity maintenance durability and surface durability of the low-emissivity film unit 100 may deteriorate, and there may be a problem in that weather resistance color difference change increases. Conversely, if the thickness exceeds 2.5 μm, there may be a problem in that the emissivity increases.

In addition, the protective film layer 140 of the present invention may preferably include a copolymer of urethane acrylate, epoxy-modified acrylate, and acrylic resin. In this case, the urethane acrylate and the epoxy-modified acrylate may be oligomers or resins, preferably oligomers.

Specifically, the transparent protective layer 10 of the present invention is a weight ratio of urethane acrylate, epoxy-modified acrylate and acrylic resin 1: 0.2 to 3.5: 0.05 to 2.5, preferably 1: 0.3 to 3: 0.06 to 2 It may include a copolymer copolymerized in a weight ratio of At this time, if the weight ratio of urethane acrylate and epoxy-modified acrylate is less than 1:0.2, surface hardness may be lowered, which may cause scratches during smart window film construction, and if the weight ratio exceeds 1:2.5, the smart window of the present invention The flexibility of the film is lowered and cracks may occur on the surface. In addition, if the weight ratio of urethane acrylate and acrylic resin is less than 1:0.05, the degree of crosslinking may decrease and sufficient curing may not be achieved, and a desired hardness may not be reached. If the weight ratio exceeds 1:2.5, the degree of crosslinking may decrease rises and cracks may occur on the surface.

In addition, the copolymer that can be included in the transparent protective layer 10 of the present invention may have a weight average molecular weight of 800 to 15,000, preferably 1,000 to 10,000. If the weight average molecular weight is less than 800, the transparent protective layer 10 may become too hard and cracks may occur, and if the weight average molecular weight exceeds 15,000, sufficient crosslinking may not occur and complete curing may occur.

In addition, the copolymer that can be included in the transparent protective layer 10 of the present invention has an acid value of 12 or less, preferably an acid value of 10 or less, an amine value of 7 or less, and preferably an amine value of 5 or less. there is. If the acid value exceeds 12, there may be a problem of deterioration in durability and a large change in color difference in weather resistance due to a radical reaction by light on the metal surface, and if the amine value exceeds 7, there may be a problem of yellowing due to ultraviolet rays. .

2. Liquid crystal film part

The liquid crystal film unit 200 is a part that can variably control the light transmittance of the smart window film by applying external stimuli such as voltage, heat, and light, and can have high transmittance, low sheet resistance, and fast response speed. In particular, the liquid crystal of the liquid crystal unit 230 has a negative dielectric anisotropy (Δ∈), and thus has a function of lowering transparency due to a change in refractive index when voltage is applied.

According to a preferred embodiment of the present invention, the liquid crystal film unit 200 sequentially includes a liquid crystal film base layer 210, a first electrode layer 220, a liquid crystal unit 230, and a second electrode layer 220'. can do. In this specification, for convenience, the electrode layer in contact with the liquid crystal film base layer 210 is referred to as the first electrode layer 220, and the electrode layer formed close to the low-emissivity film unit 100 is referred to as the second electrode layer 220 '.

In addition, the liquid crystal film base layer 210 may further include an adhesive layer 240 on the opposite side of the first electrode layer 220 .

1) LCD part

The liquid crystal part of the present invention preferably includes the first alignment films 231 and 231' and a liquid crystal layer 232 interposed between the two alignment films. In this specification, for convenience, the alignment film in contact with the first electrode layer 220 is provided. The first alignment layer 231 and the alignment layer in contact with the second electrode layer are referred to as a second alignment layer 231'.

That is, in a preferred embodiment of the present invention, the liquid crystal unit may sequentially include a first alignment layer, a liquid crystal layer, and a second alignment layer.

The liquid crystal layer 232 of the present invention can be changed to a transparent, semi-transparent or opaque state by an externally applied driving voltage, thereby serving to change the transmittance of the smart window film, and polymer network liquid crystal (Polymer Network Liquid Crystal, PNLC) may include liquid crystal and polymer resin.

The liquid crystal layer preferably includes a cured product of a liquid crystal ink including a liquid crystal and a polymer resin, and the liquid crystal ink may further include a photoinitiator, a coupling agent, and a spacer.

The polymer resin may be formed by polymerization of at least one of monomers and oligomers.

The monomer may preferably be multifunctional, preferably styrene and its derivatives; methyl, ethyl, propyl, butyl, pentyl, hexyl, amyl, 2-ethylhexyl, octyl, nonyl, dodecyl, isodecyl, lauryl, hexadecyl, cyclohexyl, benzyl, methoxyethyl, ethoxyethyl, part Toxyethyl, phenoxyethyl, allyl, methallyl, glycidyl, 2-hydroxyethyl, 2-hydroxypropyl, 3-chloro-2-hydroxypropyl, dimethylaminohexyl, dimethylaminohexyl, isobornyl, etc. acrylate or methacrylate having the same substituent; Ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, tripropylene glycol, polypropylene glycol, butylene glycol, tetramethylene glycol, hexamethylene glycol, neopentine glycol, butanediol hexanediol, trimethylolpropane, pentachloride Polyfunctional acrylates or methacrylates and derivatives thereof, such as erythritol and dipentaerythritol, but are not necessarily limited thereto. can choose the appropriate one. Preferably, the monomer may be an acrylate-based monomer, and more preferably may be a multifunctional acrylate-based monomer.

In addition, the oligomer may preferably be a multifunctional oligomer and may preferably be at least one selected from aromatic urethane acrylate, aliphatic urethane acrylate, epoxy acrylate, polyester acrylate, and derivatives thereof. However, the type of oligomer is not necessarily limited thereto, and a person skilled in the art may select an appropriate oligomer among oligomers that may be used in the polymer dispersed liquid crystal in consideration of the refractive indices of the liquid crystal and the polymer. Preferably, the oligomer may be a urethane acrylate-based oligomer, and more preferably may be a multifunctional urethane acrylate-based oligomer.

The polymer resin is a polymer formed by polymerization of at least one of the oligomer and monomer, and may have a viscosity of 800 to 1500 cPs, preferably 900 to 1200 cPs. If the viscosity of the polymer resin is less than 800 cPs, the liquid crystal flows easily, which may reduce the production yield during the coating process. Conversely, if the viscosity exceeds 1500 cPs, two of the liquid crystal and polymer resin mixing processes It is difficult to mix uniformly between liquids, and it is difficult to realize a uniform thickness due to the characteristics of the gap coating method, so the optical quality of the smart window film may deteriorate.

In a preferred embodiment of the present invention, the liquid crystal may have a dielectric constant anisotropy (Δε) of -6.0 to -1.0 and a refractive index anisotropy (Δn) of 0.07 to 0.15.

Since the dielectric constant anisotropy has a negative value, when a voltage is applied, the liquid crystal molecules receive a force such that the long axis direction is perpendicular to the electric field direction, and accordingly, the orientation of the liquid crystal is randomized and the transparency is lowered.

If the dielectric constant anisotropy is less than -6.0, since the arrangement of the liquid crystal molecules is rather more aligned when a voltage is applied, there may be a problem in that the functionality as a smart window is lowered because the decrease in light transmittance and the generation of haze are not obvious.

Conversely, when the dielectric constant anisotropy exceeds -1.0, the liquid crystal molecules are less affected by the electric field when the dielectric constant anisotropy is less than 0, so the transmittance decrease and haze generation due to voltage application do not occur clearly, so that the privacy protection function can be sufficiently performed as a smart window film. An inexplicable problem arises. If the dielectric constant anisotropy exceeds 0, the long axis direction of the liquid crystal molecules is aligned parallel to the electric field when a voltage is applied, and therefore, it does not operate as a reverse driving smart window film desired in the present invention.

In the case of refractive index anisotropy, if the refractive index anisotropy of the liquid crystal is less than 0.07, the change in refractive index due to the rotation of the liquid crystal molecules is not clear, so the decrease in transmittance and the occurrence of haze do not sufficiently occur, and therefore the privacy protection function of the smart window may not be properly expressed. there is. In addition, when the refractive index anisotropy exceeds 0.15, there may be a problem in that the transmittance decreases or the viewing angle decreases when no voltage is applied.

In a preferred embodiment of the present invention,

The liquid crystal is a bicyclohexyl-based compound, a cyclohexylphenyl-based compound, a cyclohexene-based compound, a cyclohexylcarboxylic acid ester-based compound, a difluorine phenylene ( phenylene), a bicyclo hydrocarbon compound, and a tricyclo hydrocarbon compound. However, the liquid crystal compound is not necessarily limited to the above compounds, and sugars that have dielectric constant and refractive index anisotropy necessary for achieving the object of the present invention, can be well dispersed in a polymer resin, and can be well aligned in one direction by an alignment layer. A person skilled in the art can easily select among liquid crystal compounds that can be used in the industry.

In a preferred embodiment of the present invention, the liquid crystal ink may include the liquid crystal and the polymer resin in a weight ratio of 30:70 to 55:45. More preferably, it may be included in a weight ratio of 35:65 to 50:50, and most preferably 40:60 to 50:50.

If the weight ratio of the liquid crystal is less than 30% of the sum of the weight of the liquid crystal and the polymer resin, the adhesion of the liquid crystal layer to the alignment film increases, but the crosslinking degree of the polymer resin increases and the alignment performance of the liquid crystal deteriorates, thereby reducing the transmittance and haze of the smart window film There is a problem that the rate of change is low. In addition, conversely, when the weight ratio of the liquid crystal exceeds 55%, the adhesion of the liquid crystal layer to the alignment layer is reduced, resulting in a decrease in durability.

In addition, the liquid crystal layer 232 may have a thickness of 10 to 25 μm, preferably a thickness of 16 to 24 μm, and most preferably a thickness of 18 to 22 μm. If the thickness is less than 10 μm, the uniformity of the product There is a problem in that mura defects may occur, haze cannot be sufficiently generated, and adhesion to the alignment layer decreases. If the thickness exceeds 25 μm, transmittance decreases when no voltage is applied, driving power increases, and reagent There may be a problem with the angle deterioration.

In a preferred embodiment of the present invention, the first alignment layer 231 and the second alignment layer 231' include a polyimide-based polymer, and each independently may have a thickness of 100 to 300 nm. However, it is not necessarily limited to the polyimide-based polymer, and may be formed as a polymer layer having a uniform thickness having properties such as thin film coating, high purity, and storage stability.

The alignment layer induces alignment of the liquid crystal molecules in the liquid crystal layer 232 due to the alignment of the side chains, so that the liquid crystal molecules in the liquid crystal layer 232 can be aligned in a direction perpendicular to the alignment layer when no voltage is applied. Accordingly, the liquid crystal layer 232 according to the present invention has high transmittance and low haze when voltage is not applied, resulting in high transparency.

When the thickness of the alignment film is less than 100 nm, the absolute amount of side chains capable of orienting the liquid crystal may not be properly aligned, and when the thickness exceeds 300 nm, the polyimide material, which is the main raw material of the alignment film, is colored. may deteriorate the optical properties of the sample.

In a preferred embodiment of the present invention, the liquid crystal layer may have an adhesive force of 10 to 100 gf/inch to the alignment layer measured according to the following measurement method with respect to the alignment layer.

[measurement method]

The first alignment layer and the second alignment layer of the reverse-driving smart window film are separated by 180 degrees at a speed of 10 mm/min, and the adhesion of the liquid crystal layer to the alignment layer is measured.

If the adhesive strength is less than 10 gf/inch, the durability of the smart window film may deteriorate. Conversely, if the adhesive strength exceeds 100 gf/inch, there is no problem in durability, but the performance of the liquid crystal molecule is deteriorated, resulting in a decrease in the light transmittance of the smart window film. And there may be a problem that the haze change rate is lowered.

2) electrode layer

The liquid crystal film unit 200 of the present invention further includes electrode layers 220 and 220' formed on both sides of the liquid crystal unit 230. As described above, the electrode layer in contact with the liquid crystal film base layer 210 is referred to as the first electrode layer 220, and the electrode layer closer to the low-emissivity film unit 100 is referred to as the second electrode layer 220'.

Driving power is applied to the first electrode layer 220 and the second electrode layer 220 ′, and serves to supply the applied driving power to the liquid crystal unit 230 . The first electrode layer 220 and the second electrode layer 220' of the present invention may each include at least one selected from various metals, metal oxides, and conductive polymers having conductivity, and preferably indium tin oxide (indium tin oxide). oxide, ITO) and conductive polymers, and more preferably indium tin oxide (ITO).

The first electrode layer 220 and the second electrode layer 220' may each independently have a thickness of 15 to 40 nm, preferably 20 to 30 nm, and more preferably 22.5 to 27.5 nm. If the thickness of the electrode layers 220 and 220' is less than 15 nm, resistance may increase and the reaction rate may decrease. If the thickness exceeds 40 nm, the transmittance of the substrate may decrease, resulting in visibility problems.

In addition, the first electrode layer 220 and the second electrode layer 220' each independently have a sheet resistance of 30 to 200 Ω/□, preferably 80 to 180 Ω/□, more preferably 135 to 165 Ω/□ can be

If the sheet resistance of the electrode layer (220, 220 ') is less than 30 Ω / □, the transmittance of the substrate may be lowered and there may be a problem in visibility, and if it exceeds 200 Ω / □, there is a problem that the reaction speed of the liquid crystal part is lowered can

3) Liquid crystal film base layer

Next, the liquid crystal film base layer 90 of the present invention serves as a support layer for the reverse film unit, and may include any material commonly used in the art without limitation, preferably glass and PET (Polyethylene terephthalate). ), and more preferably may include plasma or corona surface-treated PET.

In addition, the liquid crystal film base layer 90 of the present invention may have a thickness of 10 to 190 μm, preferably a thickness of 40 to 60 μm, and more preferably a thickness of 45 to 55 μm, if the thickness is 10 μm If it is less than 100%, in manufacturing the smart window film, deformation of the substrate due to heat generated during drying and curing may occur, and a problem of tearing due to tension applied to the substrate during the roll-to-roll process may occur. In addition, if the thickness exceeds 190 μm, there may be a problem of increasing the process time due to the increase in the cost of raw materials and the length that can be wound on one roll, which increases the replacement time of the roll.

4) adhesive layer

According to a preferred embodiment of the present invention, the liquid crystal film unit 200 may further include an adhesive layer 240 . The adhesive layer 240 serves to adhere the smart window film to the glass, and may include any component of the adhesive layer that can be commonly used in the smart window film without limitation, preferably polyester resin, urethane resin, It may include at least one selected from resins including acrylic resins and derivatives thereof, and may preferably include acrylic resins.

In addition, the pressure-sensitive adhesive layer 100 of the present invention may have a thickness of 10 to 30 μm, preferably 16 to 24 μm, and more preferably 18 to 22 μm, and if the thickness is less than 10 μm, the adhesive strength may decrease. If the thickness exceeds 30 μm, the raw material cost increases and the curing time increases, resulting in a decrease in production rate and a large amount of heat required, resulting in increased energy consumption.

Meanwhile, the pressure-sensitive adhesive layer 100 of the present invention may further include an ultraviolet/near infrared ray blocking agent in order to provide more excellent ultraviolet and near infrared ray blocking performance. The ultraviolet/near-infrared ray blocker may include any ultraviolet/near-infrared ray blocker commonly used in the art without limitation, and is preferably tungsten trioxide, antimony tin oxide (ATO), or indium tin oxide. , Cesium Tungstate Oxide (CTO) and zinc oxide (Zinc Oxide, ZnO). At this time, the ultraviolet / near infrared ray blocker may be provided in the form of a sol (sol), but is not limited thereto.

Hereinafter, the manufacturing process of the reverse driving smart window film according to a preferred embodiment of the present invention will be described step by step. Among them, parts overlapping with the contents described in each component of the reverse driving smart window film will be omitted.

The reverse drive smart window film according to the present invention is manufactured by a process having the following steps.

Step 1: A first film unit in which a first electrode layer and a first alignment layer are sequentially formed on one surface of the liquid crystal film base layer; and preparing a second film unit in which a second electrode layer and a second alignment layer are sequentially formed on one surface of the low-emissivity film base layer.

Step 2: The first alignment film of the first film part and the second alignment film of the second film part face each other, and liquid crystal ink containing liquid crystal having negative dielectric anisotropy is introduced between the first alignment film and the second alignment film, and then laminated. and curing to form a liquid crystal layer between the first alignment layer and the second alignment layer to obtain a smart window film.

That is, the present invention relates to a first film part and a second film part in which the electrode layers 220 and 220' and the alignment films 231 and 231' are sequentially formed on the two substrates 110 and 210 centering on the liquid crystal layer 232, respectively. After preparing the film part, facing the first alignment film 231 and the second alignment film 231' formed on the first film part and the second film part, liquid crystal ink is introduced therebetween and laminated to form a laminate. It is manufactured by a method of forming a liquid crystal layer 232 by manufacturing and curing the liquid crystal ink of the laminate.

Since the reflective metal layer 130 and the metal oxide layers 120 and 120', which function as the low-emissivity film unit 100, are absent in the laminate formed by the above method, it is necessary to form them.

Methods for forming the low-emissivity film portion are divided into two types.

In the first method, the first metal oxide layer 120, the reflective metal layer 130, and the second metal oxide layer 120' are sequentially formed on the surface opposite to the surface on which the electrode layer 220' of the low-emissivity film base layer 110 is formed. ) is formed to manufacture a first film part, and there is a method of laminating this second film part and liquid crystal ink via a liquid crystal ink.

According to this method, only two base films (110, 210) need to be used, and the process of laminating the low-emissivity film unit 100 and the liquid crystal film unit 200 is unnecessary, so the thickness is reduced and the process is simplified. there is.

In the second method, a low-emissivity film is prepared by sequentially forming a first metal oxide layer 120, a reflective metal layer 130, and a second metal oxide layer 120' on one surface of the low-emissivity film base layer 110,

The second electrode layer 220' and the second alignment film 230' are formed on a separate substrate layer (the same film as the low-emissivity film substrate layer or the liquid crystal film substrate layer can be used) to form the second film portion and the alignment film ( 230 and 230') to face each other, introduce liquid crystal ink therebetween, laminate and cure to form a liquid crystal film, and combine the low-emissivity film and the liquid crystal film with an adhesive to manufacture a smart window film.

In the case of this method, there is a disadvantage in that the thickness increases, but there is an advantage in that the implementation performance increases because the low-emissivity film and the liquid crystal film can be manufactured as independent products.

At this time, in the case of forming the electrode layers 220 and 220', the metal oxide layers 120 and 120', and the reflective metal layer 130 on each substrate, they can be formed through the deposition process as described above. Preferably, a sputtering process may be used.

In addition, the alignment layers 231 and 231', the adhesive layer, and the protective film layer may be formed by a coating process. The coating method may be selected without limitation from methods usable in the art, but preferably gravure coating or spin coating may be performed.

In a preferred embodiment of the present invention, curing in the second step may be UV curing.

In a preferred embodiment of the present invention, in the second step, curing may be performed by irradiating ultraviolet rays having an intensity of 1 to 10 mW/cm ² for 1000 to 5000 seconds.

The intensity of the ultraviolet light is more preferably 4 to 9 mW/cm ² , more preferably 6 to 8 mW/cm ² . If the intensity of the ultraviolet rays is less than 5 mW/cm ² , the adhesion between the alignment layer and the liquid crystal layer may be insufficient, which may be a reason for lowering durability of the smart window film. Conversely, if the intensity of the ultraviolet rays exceeds 10 mW/cm ² , the adhesive strength may increase, but the side chain of the alignment layer may be decomposed, which may cause the transparency of the smart window film to decrease when voltage is not applied. there is.

The present invention also, windows and doors; and the reverse driving smart window film provided on at least one surface of the window or door.

Hereinafter, examples of the present invention will be described in detail with respect to its effects. However, the technical idea of the present invention is not limited to the following examples, and the following examples are merely exemplary embodiments to aid understanding of the present invention, and those skilled in the art are within the scope of the technical idea of the present invention. In order to achieve individual purposes, it should be understood that it can be easily implemented by adding, omitting, and changing configurations.

<Example>

Example 1: Manufacturing of smart window film

1) Preparation of liquid crystal ink:

A mixture of 0.7 g of aliphatic urethane acrylate, 0.1 g of butyl acrylate, 0.1 g of benzyl acrylate, 0.1 g of hydroxyphenoxypropyl acrylate and 0.1 g of 2,4,6-trimethylbenzoyldiphenyl phosphine oxide as a polymerization initiator A liquid crystal ink was prepared by mixing a total of 1.1 g of the polymer resin composition and 0.9 g of NVJ-71 as a liquid crystal compound.

2) Manufacture of Laminates:

A solution obtained by dissolving polyimide at a concentration of 5 wt% in normal-methyl-2-pyrrolidone solvent as an alignment film solution on the electrode surface of a PET substrate (thickness of 188 μm) on which an ITO electrode (thickness of 25 nm) was formed through a sputtering process was applied. It was coated using a spin coater and heat treated in an oven at 130° C. for 10 minutes to form an alignment film with a thickness of 150 nm.

Two substrates are prepared, and one is referred to as an upper substrate and the other as a lower substrate.

A ZTO layer, an APC layer, and a ZTO layer were sequentially formed to thicknesses of 30 nm, 15 nm, and 30 nm, respectively, by performing sputtering on the surface opposite to the alignment layer of the upper substrate. The liquid crystal ink was dropped on the alignment film of the upper substrate, and then bonded to the alignment film of the lower substrate, and then gap coating was performed under the condition that the thickness of the liquid crystal layer was 10 μm to obtain a laminate.

3) UV curing

The laminate was irradiated with ultraviolet rays for 1500 seconds using a BL lamp having an illuminance of 2 mW/cm ² to obtain a reverse driving smart window film.

Examples 2 to 15 and Comparative Example 1

A smart window film was manufactured in the same manner as in Example 1, but the detailed configuration was different as shown in Table 1 below.

Comparative Example 1, unlike Example 1, uses a liquid crystal compound having a dielectric anisotropy of 7.1 and a refractive index anisotropy of 0.098, and is prepared as a forward driving smart window film without an alignment film, and other configurations are similar to those of Example 1. It was prepared in the same way as

In Comparative Example 2, a smart window film was manufactured in the same manner as in Example 1, except for the step of forming the ZTO and APC layers on the upper substrate.

division liquid crystal/polymer
weight ratio liquid crystal
type UV illuminance
(mW/cm ² ) liquid crystal layer thickness
(μm) Alignment layer thickness
(nm) low emission film
existence and nonexistence Example 1 45:55 NVJ-71 2 10 150 ○ Example 2 35:65 NVJ-71 2 10 150 ○ Example 3 50:50 NVJ-71 2 10 150 ○ Example 4 55:45 NVJ-71 2 10 150 ○ Example 5 60:40 NVJ-71 2 10 150 ○ Example 6 50:50 NVJ-71 5 10 150 ○ Example 7 50:50 NVJ-71 7.5 10 150 ○ Example 8 50:50 NVJ-71 10 10 150 ○ Example 9 50:50 NVJ-71 14.5 10 150 ○ Example 10 50:50 NVJ-71 2 5 150 ○ Example 11 50:50 NVJ-71 2 18 150 ○ Example 12 50:50 NVJ-71 2 20 150 ○ Example 13 50:50 NVJ-71 2 22 150 ○ Example 14 50:50 NVJ-71 2 25 150 ○ Example 15 50:50 NVJ-71 2 30 150 ○ Example 16 50:50 NVJ-71 2 20 80 ○ Example 17 50:50 NVJ-71 2 20 400 ○ Comparative Example 1 45:55 NTJ-10 2 10 - ○ Comparative Example 2 45:55 NVJ-71 2 10 150 × * NVJ-71 is a liquid crystal compound with dielectric constant anisotropy (Δε) of -3.5 and refractive index anisotropy (Δn) of 0.102.
* NTJ-10 is a liquid crystal compound with dielectric constant anisotropy (Δε) of 7.1 and refractive index anisotropy (Δn) of 0.098.

<Experimental example>

Experimental Example 1: transmittance and haze measurement

Transmittance and haze of the smart window films prepared according to Examples and Comparative Examples were measured using a BYK haze-gard plus spectroscopic haze meter.

Specifically, the opaque state due to diffusion in addition to reflection or absorption was measured by transmitting light through the smart window film using the above equipment. The measurement was divided into when no voltage was applied (OFF) and when a voltage of 80 V was applied between both electrodes (ON).

Experimental Example 2: Measurement of adhesive strength of liquid crystal

Prepare the adhesive force measurement specimens according to Examples and Comparative Examples, respectively, and prepare the adhesive force test specimens by cutting the prepared test specimens to a width of 1 inch.

Fold the upper board of the test piece and prepare the test piece so that it can be pulled in the direction of 180 degrees. At this time, the total length of the attached liquid crystal layer should be 100 mm or more. The prepared specimen was pulled at a speed of 10 mm/min using UTM equipment and the value was measured. At this time, the measured length was 100 mm, and the average value from the initial 10 mm section to the 90 mm section was recorded.

Experimental Example 3: Measurement of emissivity and solar heat gain

The ratio of the thermal radiation radiation power emitted by the glass plate to the space to the thermal radiation radiation power emitted by a black body at the same temperature. The vertical emissivity value (corrected emissivity) calculated by the method specified in KS L2514 using the spectral reflectance measured by the measuring instrument is shown.

In addition, the ratio of the sum of the radiant flux of solar radiation passing through the glass part and the heat flux absorbed by the glass to the radiant flux of the incident solar radiation to the solar radiation incident vertically on the window glass surface, KS The solar heat acquisition rate was measured by the test method of L 2514.

The results evaluated according to the experimental example are shown in Table 2 below.

division emissivity
(%) solar gain rate
(%) adhesiveness
(gf/inch) Light transmittance (OFF/ON)
(%) Haze (OFF/ON)
(%) Example 1 0.13 0.26 7.8 78.1/8.3 7.0/95.3 Example 2 0.13 0.26 7.7 78.4/78.9 6.6/84.1 Example 3 0.13 0.26 4.2 77.8/16.2 10.2/90.9 Example 4 0.13 0.26 2.6 71.6/26.2 20.0/82.9 Example 5 0.13 0.26 0.8 58.8/27.7 39.1/80.7 Example 6 0.13 0.26 8.3 81.1/5.6 5.6/98.7 Example 7 0.13 0.26 9.2 81.6/6.3 4.7/97.6 Example 8 0.13 0.26 11.9 80.9/9.8 5.1/92.9 Example 9 0.13 0.26 19.8 77.8/9.5 9.3/93.7 Example 10 0.13 0.26 5.3 82.3/20.1 3.2/78.9 Example 11 0.13 0.26 7.6 76.4/10.1 10.2/94.0 Example 12 0.13 0.26 7.2 77.0/9.8 8.6/95.9 Example 13 0.13 0.26 7.2 73.8/8.1 12.9/96.5 Example 14 0.13 0.26 9.6 65.7/24.9 28.6/82.5 Example 15 0.13 0.26 12.3 43.6/50.7 52.9/72.3 Example 16 0.13 0.26 7.7 88.6/7.9 11.2/87.2 Example 17 0.13 0.26 7.9 68.1/4.7 16.2/94.4 Comparative Example 1 0.08 0.18 7.7 6.5/88.1 91.6/10.8 Comparative Example 2 0.21 0.44 7.6 78.4/9.1 89.6/9.1

Referring to Table 2, the smart window films of Examples using NVJ-71 having negative dielectric constant anisotropy as a liquid crystal had higher transmittance when voltage was not applied than transmittance when voltage was applied, and haze was the opposite.

However, it was confirmed that the smart window film according to Comparative Example 1 had a higher transmittance when voltage was applied than that when no voltage was applied, and a lower haze when voltage was applied than when it was not applied, thereby operating in the opposite manner.

In addition, Comparative Example 2 was able to confirm that the emissivity and the solar heat gain rate were significantly higher than those of Example 2, which did not include the low-emissivity film portion.

In addition, it was confirmed that as the liquid crystal content in the liquid crystal layer increased, the adhesiveness of the liquid crystal layer to the alignment film layer decreased. Adhesion and transmittance change were excellent when the content of liquid crystal was 55% or less, and 45% was the best.

In addition, as a result of varying the UV curing conditions, it was found that the adhesive strength increased as the UV intensity increased, but the change in haze and light transmittance gradually decreased. A suitable range was 10 mW/cm ² or less.

In addition, when the thickness of the liquid crystal layer was 20 μm, the difference in transmittance and haze when voltage was applied/unapplied increased, and when the thickness exceeded 25 μm or less than 10 μm, it was confirmed that these optical properties were remarkably deteriorated.

If the thickness of the alignment layer is too small, there is a problem of insufficient alignment of the liquid crystal, and if the thickness is too large, it can be confirmed that the alignment performance is lowered and the alignment layer has a unique color, thereby impairing the optical performance.

1000: smart window film
100: low-emissivity film unit
110: low-emissivity film base layer
120, 120': metal oxide layer
130: reflective metal layer
140: protective layer
200: liquid crystal film unit
210: liquid crystal film base layer
220, 220': electrode layer
230: liquid crystal unit
231, 231': alignment film
232 liquid crystal layer
240: adhesive layer
300: first film unit
400: second film unit

Claims (16)

a low-emission (low-E) film unit including a first metal oxide layer, a reflective metal layer, and a second metal oxide layer in sequence; and
a first electrode layer formed on one surface of the low-emissivity film unit and sequentially; A liquid crystal unit including a first alignment layer/a liquid crystal layer including a cured product of a liquid crystal ink containing a polymer resin and a liquid crystal having a negative dielectric anisotropy in a weight ratio of 45:55 to 70:30/a second alignment layer in this order; And a second electrode layer; a liquid crystal film unit including a; including,
Reverse drive smart window film, characterized in that the following conditional expression 1) is satisfied and the adhesive strength of the liquid crystal layer to the alignment layer is 10 to 100 gf / inch, measured according to the following measurement method:
1) T _on < T _off
In Conditional Expression 1), T _on represents the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when a voltage of 80V is applied between the first electrode layer and the second electrode layer, and T _off is Represents the light transmittance (%) of the reverse drive smart window film to a D65 standard light source when no voltage is applied:
[measurement method]
The first alignment layer and the second alignment layer of the reverse driving smart window film are separated by 180° at a rate of 10 mm/min to measure the adhesion of the liquid crystal layer to the alignment layer. According to claim 1,
The liquid crystal unit sequentially includes a first alignment layer, a liquid crystal layer, and a second alignment layer,
The first alignment layer and the second alignment layer include a polyimide-based polymer, and each independently has a thickness of 100 to 300 nm. According to claim 1,
The reverse driving smart window film further satisfies the following Conditional Expressions 2) and 3):
2) 6 ≤ T _off /T _on ≤ 30
3) 3% ≤ T _on ≤ 15%
In Conditional Expressions 2) and 3), T _off represents the light transmittance (%) of the reverse driving smart window film when no voltage is applied, and T _on represents the voltage of 80V between the first electrode layer and the second electrode layer. It represents the light transmittance (%) of the reverse driving smart window film when voltage is applied. According to claim 1,
The liquid crystal has a dielectric constant anisotropy (Δε) of -6.0 to -1.0 and a refractive index anisotropy (Δn) of 0.07 to 0.15. According to claim 4,
The liquid crystal is a bicyclohexyl compound, a cyclohexylphenyl compound, a cyclohexene compound, a cyclohexylcarboxylic acid ester compound, a difluoro phenylene compound, a Including at least one selected from a cyclohydrocarbon compound and a tricyclohydrocarbon-based compound,
The polymer resin may include one or more oligomers selected from aromatic urethane acrylate oligomers, aliphatic urethane acrylate oligomers, and polyester acrylate oligomers; and at least one monomer selected from acrylate-based monomers, epoxy-based monomers, and siloxane-based monomers; A reverse drive smart window film, characterized in that it is formed by polymerization of one or more of, and has a viscosity of 800 to 1500 cPs. delete According to claim 1,
The first electrode layer and the second electrode layer each independently contain at least one selected from indium tin oxide (ITO) and a conductive polymer,
Reverse driving smart window film, characterized in that each independently has a sheet resistance of 30 ~ 200Ω / □. According to claim 1,
The reflective metal layer includes a silver-palladium-copper alloy (Ag-Pd-Cu alloy, APC),
The first metal oxide layer and the second metal oxide layer are _each independently made of zinc tin oxide (Zinc Tin Oxide, ZTO) Reverse drive smart window film, characterized in that it comprises. According to claim 1,
The low-emissivity film part further includes a transparent protective layer and a low-emissivity film base layer, and the liquid crystal film part further includes a liquid crystal film base layer,
Reverse driving, characterized in that each layer is provided in the order of a liquid crystal film base layer, a first electrode layer, a liquid crystal unit, a second electrode layer, a low-emissivity film base layer, a first metal oxide layer, a reflective metal layer, and a second metal oxide layer. Smart Window Film. According to claim 1,
The reverse drive smart window film has a total thickness of 50 to 200 μm,
Reverse driving smart window film, characterized in that the thickness ratio between the low-emission film part and the liquid crystal film part is 1: 1 to 2.5. delete a first film unit in which a first electrode layer and a first alignment layer are sequentially formed on one surface of the liquid crystal film base layer; and a first step of preparing a second film unit in which a second electrode layer and a second alignment layer are sequentially formed on one surface of the low-emissivity film base layer; and
The first alignment film of the first film part and the second alignment film of the second film part face each other and liquid crystal ink containing a polymer resin and a liquid crystal having a negative dielectric anisotropy in a weight ratio of 45:55 to 70:30 Liquid crystal ink a second step of obtaining a smart window film by introducing a liquid crystal layer between the first alignment layer and the second alignment layer by laminating and curing the layer between the first alignment layer and the second alignment layer;
including,
The smart window film satisfies the following conditional expression 1), and the adhesive strength of the liquid crystal layer to the culture film measured by EK in the following measurement method is 10 to 100 gf / inch Manufacturing method of a reverse driving smart window film:
1) T _on < T _off
In Conditional Expression 1), T _on represents the light transmittance (%) of the reverse driving smart window film with respect to the D65 standard light source when a voltage of 80V is applied between the first electrode layer and the second electrode layer, and T _off is Represents the light transmittance (%) of the reverse drive smart window film to a D65 standard light source when no voltage is applied:
[measurement method]
The first alignment layer and the second alignment layer of the reverse driving smart window film are separated by 180° at a rate of 10 mm/min to measure the adhesion of the liquid crystal layer to the alignment layer. According to claim 12,
The second film unit sequentially forms a first metal oxide layer, a reflective metal layer, and a second metal oxide layer on one surface of the low-emissivity film base layer,
The method of manufacturing a reverse driving smart window film, characterized in that manufactured by sequentially forming the second electrode layer and the second alignment film on the other surface of the low-emissivity film base layer. According to claim 12,
Curing in the second step is a method of manufacturing a reverse driving smart window film, characterized in that UV curing. According to claim 12,
The method of manufacturing a smart window film, characterized in that in the second step, curing is performed by irradiating ultraviolet rays with an intensity of 1 to 10 mW / cm ² for 1000 to 5000 seconds. window; and a reverse driving smart window film according to any one of claims 1 to 5 and 7 to 10 provided on at least one surface of the window or door.

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