JP2022173038A - Transparent heat insulation film - Google Patents

Abstract

To provide a transparent heat insulation film comprising a silver nanowire layer having excellent heat radiation and insulation effect, excellent optical properties and high hardness.SOLUTION: The transparent heat insulation film comprises a base layer 1 including a first surface 11 and a second surface 12, a hard coat layer 2, a silver nanowire layer 3, and a protective layer 4 including an internal surface and an external surface. The hard coat layer and the silver nanowire layer are arranged between the first surface of the base layer and the internal surface 41 of the protective layer. The temperature of the second surface of the base layer is T1 (°C), the temperature of the external surface 42 of the protective layer is T2 (°C), and the temperature difference (T1-T2) between T1 and T2 is ▵T. If the base layer and the protective layer reach the thermal equilibrium when T1=50-100°C, then ▵T=0.15 T1 to 0.35 T1.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a transparent heat insulating film, and more particularly to a transparent heat insulating film for touch panels.

With the spread of electronic devices, there is a demand for the appearance of electronic devices to be lighter and thinner. However, since it becomes difficult to dissipate heat from these thinned electronic devices, the surface temperature of these electronic devices rises significantly, especially in the case of large and thin display panels. Therefore, in the process of designing large-scale integrated circuits and packaging electronic devices, the problem of heat dissipation remains an urgent issue.

In order to solve the heat dissipation problem of such high heat electronic products, most products have a heat insulating film on the surface of the product to avoid problems such as overheating when the user touches the electronic product. be. At present, heat sinks made of metals with high thermal conductivity are often installed on the surface of electronic devices, and silver, copper, aluminum, etc. are generally used as thermally conductive metals. However, when better heat dissipation and heat insulation are required, the amount of thermally conductive metal must be increased. The optical properties of the display panel are affected.

Chinese Patent Application Publication No. 109853794 Chinese Patent Application Publication No. 106977985 Chinese Patent Application Publication No. 111471299

The present disclosure provides a novel transparent thermal insulation film comprising a base layer including first and second surfaces, a hardcoat layer, a silver nanowire layer, and a protective layer including inner and outer surfaces. do. The hardcoat layer and the silver nanowire layer are disposed between the first surface of the base layer and the inner surface of the protective layer. The temperature of the second surface of the base layer is T1 (° C.), the temperature of the outer surface of the protective layer is T2 (° C.), and the temperature difference (T1−T2) between T1 and T2 is ΔT. When both the base layer and the protective layer reach thermal equilibrium at T1=50-100° C., ΔT=0.15T1-0.35T1.

In one embodiment of the present disclosure, the transparent thermal insulation film has a transparency of 85-99%, a haze of the transparent thermal insulation film of 0.5-2.5%, and a reflectance of 0.5-2% at a wavelength of 550 nm.

In one embodiment of the present disclosure, the silver nanowire layer has a surface resistance of 10-150 ops.

In one embodiment of the present disclosure, the time required for both the second surface of the base layer and the outer surface of the protective layer to reach thermal equilibrium is less than 5 minutes.

In one embodiment of the present disclosure, a hardcoat layer is disposed on the first surface of the base layer, a silver nanowire layer is disposed on the hardcoat layer, and a protective layer is disposed on the silver nanowire layer.

In one embodiment of the present disclosure, the transparent heat insulating film further comprises an antireflection film including an adhesive surface and a touch surface, and the antireflection film is attached to the outer surface of the protective layer via the adhesive surface of the antireflection film. there is

The present disclosure provides a base layer including a first surface and a second surface, a hard coat layer, a silver nanowire layer, a protective layer including an inner surface and an outer surface, and an antireflective film including an adhesive surface and a touch surface. and to provide another novel transparent heat insulating film. The inner surface of the protective layer faces the silver nanowire layer. The hard coat layer and the silver nanowire layer are disposed between the first surface of the base layer and the inner surface of the protective layer, and the antireflection film is attached to the outer surface of the protective layer via an adhesive surface. The temperature of the second surface of the base layer is T3 (°C), the temperature of the touch surface of the antireflection film is T4 (°C), and the temperature difference between T3 and T4 (T3-T4) is ΔT. When the base layer and the antireflection film reach thermal equilibrium at T3=50-100° C., ΔT=0.12T3-0.32T3.

In one embodiment of the present disclosure, the silver nanowire layer has a surface resistance of 10-40 ops.

In one embodiment of the present disclosure, a hardcoat layer is disposed on the first surface of the base layer, a silver nanowire layer is disposed on the hardcoat layer, and a protective layer is disposed on the silver nanowire layer.

In one embodiment of the present disclosure, an antireflective film includes a high refractive layer and a low refractive layer laminated together.

In one embodiment of the present disclosure, the refractive index of the high refractive layer is 1.6-1.7 and the refractive index of the low refractive layer is 1.3-1.4.

In one embodiment of the present disclosure, the transparent thermal insulation film has a hardness of 2H or higher.

Note that the term "above" may be used herein to describe relative positions between components. For example, a first element positioned “above” a second element includes embodiments in which the first element is formed in direct contact with the second element, where the first element and the second element It may also include embodiments in which additional components may be formed between.

Furthermore, the term "thermal equilibrium" can be used herein to describe the state in which there is no change in the temperature gradient between the layers of the transparent insulating film. For example, in the present disclosure, if the temperature difference between the outer surface of the protective layer and the second surface of the base layer remains the same after the second surface of the base layer has been heated to a temperature for a period of time, The base layer and protective layer reach thermal equilibrium.

In the present disclosure, the silver nanowire layer of the transparent heat insulating film, which functions as a heat insulating material, has excellent heat dissipation and heat insulating effect, excellent optical properties, and high hardness. In addition, even in a high-temperature and high-humidity environment, the silver nanowires can be prevented from being damaged, and the storage stability can be effectively improved.

1 is a cross-sectional view of the transparent heat insulating film of the first embodiment of the present disclosure; FIG. FIG. 4 is a cross-sectional view of a transparent heat insulating film according to a second embodiment of the present disclosure; 4 is a stability test result of the transparent heat insulating film of the second embodiment of the present disclosure;

First, a cross-sectional view of the transparent heat insulating film 1000 of the first embodiment of the present disclosure is shown in FIG. 4. Base layer 1 has a first surface 11 and a second surface 12 . The thickness of the base layer 1 can be 40-100 μm, and the base layer 1 can be made of glass, sapphire, acrylic (PMMA), polyvinyl chloride (PVC), polypropylene (PP), polyethylene terephthalate (PET), It can be made from polyethylene naphthalate (PEN), polycarbonate (PC), polystyrene (PS), polyimide, cellulose triacetate film (TAC film), and other transparent materials, but the disclosure is not limited thereto.

Hard coat layer 2 is formed on first surface 11 of base layer 1 . The thickness of the hard coat layer 2 can be 0.5 to 2.0 μm, and the hard coat layer 2 contains a curable resin such as melamine resin, urethane resin, alkyd resin, acrylic resin, and silicone resin. Although it can be formed by a cured film, the present disclosure is not limited to this.

The silver nanowire layer 3 is formed on the hard coat layer 2, and the surface resistance of the silver nanowire layer 3 can be 10 to 150 ops (ohm per square, Ω/□).

A protective layer 4 is formed on the silver nanowire layer 3 to protect the silver nanowire layer 3 . The protective layer 4 has an inner surface 41 and an outer surface 42 , the inner surface 41 facing and contacting the silver nanowire layer 3 . The thickness of the protective layer 4 can be 40-100 nm, and the protective layer 4 is made of materials known in the art for protective films, such as polyester, polyethylene terephthalate (PET), polybutylene terephthalate (PBT). ), polymethyl methacrylate (PMMA), acrylic resin, polycarbonate (PC), polystyrene (PS), polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyvinylidene chloride (PVDC), polyethylene (PE), ethylene vinyl acetate It can be a copolymer (EVA), polyurethane (PU), cellophane, polyolefin, cyclic olefin copolymer (COP), polytetrafluoroethylene (PTFE), or mixtures thereof.

A cross-sectional view of the transparent thermal insulation film 2000 of the second embodiment of the present disclosure is shown in FIG. An antireflection film 5 is provided.

In the second embodiment of the present disclosure, the base layer 1, the hard coat layer 2, the silver nanowire layer 3 and the protective layer 4 are the same as those described in the first embodiment, but the antireflection film 5 protects It is arranged on the outer surface 42 of layer 4 .

The antireflection film 5 has an adhesive surface 51 and a touch surface 52 , the adhesive surface 51 being attached to the outer surface 42 of the protective layer 4 . The antireflection film 5 may have a laminated structure of a high refractive layer 53 and a low refractive layer 54. The high refractive layer 53 may have a refractive index of 1.6 to 1.7. can be 50-100 nm. The refractive index of the low refractive layer 54 can be 1.3-1.4, and the thickness of the low refractive layer 54 can be 100-200 nm. The high refractive layer 53 and low refractive layer 54 are arranged to adjust the optical properties of the transparent heat insulating film 2000 .

[Evaluation of optical properties and heat insulation effect of transparent heat insulation film]
First, prepare a laminated structure in which a base layer, a hard coat layer, and a silver nanowire layer are sequentially laminated, and the silver nanowire layers having surface resistances <10, 15, 20, 150 ops due to different amounts of silver nanowires. are prepared as Examples 1 to 4, respectively. A laminated structure in which a base layer, a hard coat layer, a high refractive layer, and a low refractive layer are sequentially laminated is prepared as Comparative Example 1. In this evaluation, the laminate structures of Examples 1-4 and Comparative Example 1 are tested for transparency, haze and reflectance. In addition, the second surface of the base layer of Examples 1 to 4 and Comparative Example 1 is attached to a constant temperature heating plate set at 50° C. (T1) to carry out the evaluation method of the heat insulating effect. After thermal equilibration, the temperature (T2) of the exposed surface of the silver nanowire layers of Examples 1-4 and the low-refractive layer of Comparative Example 1 is measured with a thermal imaging device (infrared (IR) camera). The heat insulating effect is evaluated from the temperature difference (ΔT) between the two surfaces. Table 1 shows the evaluation results. Note that the amount of silver nanowires in the silver nanowire layer can affect the visibility of the transparent thermal insulation film if the surface resistance of the silver nanowire layer is less than 10 ops. On the contrary, when the surface resistance of the silver nanowire layer is over 150 ops, the heat insulating effect is inefficient.

In order to meet the requirements of the thermal insulation effect and visibility of the transparent thermal insulation film, the surface resistance of the silver nanowire layer is preferably 15-150 ops, more preferably 15-50 ops, most preferably 15-25 ops, so that , transparency of 85-99%, haze of 0.5-2.5%, and reflectance (550 nm) of 0.5-2% can be achieved.

Next, a transparent thermal insulation film with a 25 ops silver nanowire layer is prepared as Example 5. The second surface of the base layer is heated to 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., and 110° C. (heat plate temperature T1), while the exposure temperature of the silver nanowire layer ( T2) is measured after reaching thermal equilibrium. The temperature difference ΔT was calculated in order to evaluate the heat insulating effect, and the results are shown in Table 2.

According to the results shown in Tables 1 and 2, between the hot plate temperature T1 and the temperature difference ΔT based on the transparent heat insulating film having the silver nanowire layer, ΔT (° C.) = 0.15T1 to 0.35T1. There is a relationship.

According to the above evaluation results, the transparent heat insulating film with silver nanowires has excellent heat insulating effect. Also, the time required to reach thermal equilibrium is very short and the temperature difference between the two surfaces remains constant for 5 minutes. Also, the temperature difference between the two surfaces can be adjusted to 7.7-16° C. depending on the amount of silver nanowires (surface resistance) in the silver nanowire layer. That is, when the temperature of the second surface of the base layer of the transparent heat insulating film is increased to 50°C, the temperature of the other surface of the transparent heat insulating film can be maintained at 34-42.3°C. Even if the temperature of the second surface of the base layer rises to 60-110°C, the temperature difference between the two surfaces of the transparent insulating film can be 17.3-37.7°C. In contrast, the temperature difference between the two surfaces of the transparent heat insulating film without the silver nanowire layer of Comparative Example 1 was only 0.4° C., indicating a low heat insulating effect. Furthermore, the transparent thermal insulation films of Examples 1-4 have excellent optical properties such as transparency of 87.6-92.9%, haze of less than 4%, and reflectance of less than 3%.

Next, a transparent heat insulating film is prepared in which a base layer, a hard coat layer, a silver nanowire layer, a protective layer and an antireflection layer are sequentially laminated. The antireflection layer includes a high refractive layer and a low refractive layer, the high refractive layer having a refractive index of 1.628 and the low refractive layer having a refractive index of 1.380. Transparent thermal insulation films having silver nanowire layers with surface resistances of 10, 20 and 40 ops are prepared as Examples 6 to 8, respectively. Comparative Example 1 above is also prepared for comparison. The optical properties and heat insulation effects of Examples 6 to 8 and Comparative Example 1 are also evaluated in the same manner as described above. That is, the second surface of the base layer is heated to 50°C (T3 (°C), the temperature of the heating plate), and the temperature T4 (°C) of the touch surface of the antireflection film after reaching thermal equilibrium is measured. to evaluate its thermal insulation effect. Table 3 shows the evaluation results.

According to the results shown in Table 3, the transparent heat insulating films provided with the antireflection layers of Examples 6 to 8 exhibit an excellent heat insulating effect with a temperature difference of 6.2 to 15.7°C between the two surfaces. Therefore, even if the user operates the touch panel and touches the touch surface of the transparent heat insulating film, the user does not feel heat. Also, the optical properties are further improved, with a transparency of 91.1-95.5%, a haze of less than 2.18%, and a reflectance of less than 2%.

In order to meet the requirements of the thermal insulation effect of the transparent thermal insulation film, the surface resistance of the silver nanowire layer with the transparent thermal insulation film is preferably 10-40 ops, more preferably 10-25 ops, most preferably 20-25 ops. . At the same time, the requirements for optical visibility of the transparent heat insulating film, 85-99% transparency, 0.5-2.5% haze, and 0.5-2% reflectance at a wavelength of 550 nm are also achieved.

As Example 9 of thermal insulation effect evaluation, a transparent thermal insulation film comprising silver nanowires with a surface resistance of 25 ops is prepared. Evaluate the thermal insulation effect in the same manner as above. That is, the second surface of the base layer was heated to 50° C., 60° C., 70° C., 80° C., 90° C., 100° C., 110° C. (T3 (° C.), the temperature of the hot plate) to reach thermal equilibrium. The thermal insulation effect is evaluated by measuring the temperature T4 (° C.) of the touch surface of the antireflection film afterward.
Table 4 shows the evaluation results.

According to the results shown in Tables 3 and 4, between the hot plate temperature T3 and the temperature difference ΔT based on the transparent heat insulating film having the silver nanowire layer, ΔT (° C.)=0.12T3 to 0.32T3 There is a relationship

Next, a high-refractive layer and a low-refractive layer having different refractive indices are used to optimize the heat-insulating effect and optical properties of the reflective film of the transparent heat-insulating film. Table 5 shows the refractive indices of the high and low refractive films and the surface resistance of the silver nanowire layers of Examples 10 to 13. The optical properties and heat insulating effect are evaluated by the methods described above. Table 5 shows the results.

According to this result, the transparent heat insulating films of Examples 10 to 13, which have a low refractive layer and a high refractive layer with different refractive indices, all exhibit excellent heat insulating effects and optical properties, and Example 13 is the most excellent. It shows thermal insulation effect and optical properties. The transparent thermal insulation film of Example 13 has a transparency of 93.8% when the refractive index of the low refractive layer is 1.383, the refractive index of the high refractive layer is 1.677, and the surface resistance of the silver nanowire layer is 25 ops. , a haze of 1.14%, a reflectance of 0.73%, and a temperature difference of 13.2°C.

Transparent heat insulating films in which a base layer, a hard coat layer, a silver nanowire layer, a protective layer and an antireflection film are sequentially laminated were prepared as Examples 14 and 15, and the refractive index of the high refractive layer was 1.677 and the low refractive index The refractive index of the layer is 1.383 and the surface resistance of the silver nanowire layer is 25 ops and 40 ops respectively. Despite the evaluation of thermal insulation effect and optical properties, we also test the hardness, scratch resistance and stability of the silver nanowire layer at 85° C. and 85% humidity in a hot and humid environment. Evaluation results are shown in Table 6 and FIG.

According to the evaluation results shown in Table 6 and FIG. 3, the transparent heat insulating films of Examples 14 and 15 have excellent heat insulating effect and optical properties. Furthermore, the transparent heat insulating films of Examples 14 and 15 have high hardness and high scratch resistance. In a high temperature and high humidity environment, the antireflection film prevents damage to the silver nanowire layer based on the test results of hardness, scratch resistance, and stability of the silver nanowire layer in a high temperature and high humidity environment of 85 ° C and 85% humidity. , the storage stability of the silver nanowire layer can be effectively improved.

The above disclosure relates to its detailed technical content and inventive features. Those skilled in the art can proceed with various modifications and replacements based on the disclosures and suggestions of the described disclosure without departing from its characteristics. Nevertheless, although such modifications and replacements have not been fully disclosed in the above description, they are substantially encompassed within the scope of the appended claims.

1 base layer 2 hard coat layer 3 silver nanowire layer 4 protective layer 5 antireflection film 11 first surface 12 second surface 25 surface resistance 41 inner surface 42 outer surface 51 adhesive surface 52 touch surface 53 high refractive layer 54 low refractive index Layers 1000, 2000 transparent thermal insulation film

Claims (12)

A transparent heat insulating film,
a base layer comprising a first surface and a second surface;
a hard coat layer;
a silver nanowire layer;
a protective layer comprising an inner surface and an outer surface;
The hard coat layer and the silver nanowire layer are disposed between the first surface of the base layer and the inner surface of the protective layer, and the temperature of the second surface of the base layer is T1 (°C. ), the temperature of the outer surface of the protective layer is T2 (° C.), the temperature difference between T1 and T2 (T1−T2) is ΔT, and the base layer and the protective layer are formed at T1=50 to 100° C. ΔT=0.15T1 to 0.35T1 when the layer reaches thermal equilibrium;
Transparent insulation film. 2. The transparent heat insulating film according to claim 1, wherein the transparency of the transparent heat insulating film is 85-99%, the haze of the transparent heat insulating film is 0.5-2.5%, and the reflectance at a wavelength of 550 nm is 0.5-2%. Transparent insulation film. The transparent thermal insulation film according to claim 1 or 2, wherein the silver nanowire layer has a surface resistance of 10-150 ops. A transparency according to any preceding claim, wherein the time required for both the second surface of the base layer and the outer surface of the protective layer to reach thermal equilibrium is less than 5 minutes. heat insulating film. 2. The hard coat layer is disposed on the first surface of the base layer, the silver nanowire layer is disposed on the hard coat layer, and the protective layer is disposed on the silver nanowire layer. 5. The transparent heat insulating film according to any one of 1 to 4. 6. The method of claim 1, further comprising an antireflection film including an adhesive surface and a touch surface, wherein the antireflection film is attached to the outer surface of the protective layer via the adhesive surface of the antireflection film. A transparent thermal insulation film according to any one of the preceding paragraphs. A transparent heat insulating film,
a base layer comprising a first surface and a second surface;
a hard coat layer;
a silver nanowire layer;
a protective layer comprising an inner surface and an outer surface;
and an antireflection film including an adhesive surface and a touch surface,
The inner surface of the protective layer faces the silver nanowire layer,
The hard coat layer and the silver nanowire layer are disposed between the first surface of the base layer and the inner surface of the protective layer, and the antireflection film covers the adhesive surface of the antireflection film. The temperature of the second surface of the base layer is T3 (° C.), and the temperature of the touch surface of the antireflection film is T4 (° C.), T3. The temperature difference (T3-T4) from T4 is ΔT, and when the base layer and the antireflection film reach thermal equilibrium at T3=50 to 100° C., ΔT=0.12T3 to 0.32T3. ,
Transparent insulation film. 8. The transparent thermal insulation film as claimed in claim 7, wherein the silver nanowire layer has a surface resistance of 10-40 ops. 8. The hard coat layer is disposed on the first surface of the base layer, the silver nanowire layer is disposed on the hard coat layer, and the protective layer is disposed on the silver nanowire layer. Or the transparent heat insulation film of 8. The transparent heat insulating film according to any one of claims 7 to 9, wherein the antireflection film comprises a high refractive layer and a low refractive layer laminated together. 11. The transparent heat insulating film according to claim 10, wherein the high refractive layer has a refractive index of 1.6 to 1.7 and the low refractive layer has a refractive index of 1.3 to 1.4. The transparent heat insulating film according to claim 10 or 11, wherein the transparent heat insulating film has a hardness of 2H or more.

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