JPWO2017200090A1 - Thin film structure for suppressing heat transfer, and structure and substrate on which the thin film structure is laminated - Google Patents

Abstract

Provided is a thin film structure capable of suppressing heat transfer from the front surface to the back surface. The thin film structure includes hollow fine particles containing a metal oxide and a base in a solidified state. The hollow particles are densely distributed in the base from one surface to at least a first position in the depth direction. When thermal energy is irradiated to the surface of the thin film structure, far infrared radiation is generated from the thin film structure, but the position of the deepest portion where the far infrared radiation is generated is from the surface to the first position At a second position less than the distance of

Description

  The present invention suppresses heat transfer due to infrared radiation from either one of the inner or outer side to the other by being laminated on the outer surface or inner surface of a building, a vehicle, various facilities, etc. The present invention relates to a thin film structure that can be made.

  In various applications such as buildings, vehicles, or various facilities (herein referred to as "structures" including these, etc.), a sealed space, for example, from inside or outside of a building or container etc. Various heat insulating materials are used for the purpose of blocking heat from the outside to the inside. The heat insulating materials mainly include fibrous heat insulating materials and foamed heat insulating materials.

  Examples of the fiber heat insulating material include glass wool, rock wool, and cellulose fibers. Examples of the foam heat insulating material include foam heat insulating materials such as urethane foam and bead method polystyrene foam. These conventional heat insulating materials have a low density due to the presence of voids inside, so the thermal conductivity is low, and as a result, the heat insulating effect is obtained. However, in order to effectively suppress the transfer of heat using these heat insulating materials, it is necessary to apply the heat insulating material thickly to the surface of the structure, and the amount of the heat insulating material used to improve the heat insulating performance As the cost of materials and construction increases with the increase of the size of the heat insulating material, the usable space decreases. As a result, conventional thermal insulation has limitations in improving the thermal insulation performance. Moreover, the conventional heat insulating material also has the subject that the followability with respect to the surface shape of a structure is bad.

  In order to solve the problem which such a conventional heat insulating material has, a so-called heat insulating coating or paint is proposed. In general, the heat insulating coating or paint is used by mixing fine particles or hollow fine particles in a base such as a resin, and directly applying this mixture to, for example, the surface of a structure or coating on a base film such as a tape. If necessary, additives that contribute to the heat insulation function may be added. Such techniques are proposed, for example, in Patent Documents 1 to 5.

  Patent Document 1 (Japanese Patent Application Laid-Open No. 11-80599) makes the whole white by dispersing white hollow beads made of glass or ceramics at a ratio of 50 to 80% by volume, and uses the reflection of light to achieve a heat shielding effect. It is a technique about the heat insulation coating film which obtains. There is also a problem that stains are noticeable by making the coating white and the use application is limited, but for this, the heat insulating coating has a two-layer structure, and the second insulating coating on the surface is white. Protect the thermal insulation coating of

In patent document 2 (Unexamined-Japanese-Patent No. 2000-71389), the 5-20 micrometers ceramic fine powder which has the property to reflect a light ray, and the 50-100 micrometers ceramic fine powder which has a heat insulation effect are disperse | distributed in a coating-film formation agent. Thermal insulating paints formed by mixing have been proposed. In this technology, for example, TiO ₂ , SnO ₂ , In ₂ O ₃ , TiN, Si ₃ N _{4 and the} like are proposed as fine powders having the property of reflecting light rays, and as fine powders having a heat insulating effect, for example, Titanates such as K ₂ O · nTiO ₂ and silicates such as CaO · nSiO ₂ have been proposed.

In Patent Document 3 (JP 2005-179514), silica _(SiO 2 · _nH 2 O) thermal insulating resin composition contains has been proposed in the binder resin. In this technology, silica has specific performance in terms of pore volume, specific surface area, mode diameter, etc., and in order to obtain better thermal insulation performance, silica has such properties. Precision is required for design and manufacture.

  In patent document 4 (Unexamined-Japanese-Patent No. 2009-108222), the heat insulation in which a large amount of nano hollow particles (particles which consist of a silica shell) of diameter 30 nm-300 nm were mixed in the coating material in 30 volume%-70 volume%. Paints have been proposed. In general, when mixing a large amount of nano hollow particles into a solvent, there is a problem that aggregation is likely to occur. However, in this document, most of the nano hollow particles are finely dispersed in a solvent by strongly dispersing the nano hollow particles in a solvent with a wet jet mill, and further, a surface modifier is added to these finely dispersed particles by reaction. The surface modification is said to prevent aggregation and finely disperse in the paint.

  Patent Document 5 (Japanese Patent Application Laid-Open No. 2000-290594) proposes a heat insulating film in which the workability is improved by applying and drying a high performance heat insulating paint consisting of an emulsion of micro ceramic balloons and an adhesive resin on the film in advance. It is

JP-A-11-80599 Japanese Patent Laid-Open No. 2000-71389 Patent document 1: JP-A-2005-179514 JP, 2009-108222, A Japanese Patent Laid-Open No. 2000-290594

E. D. Palik Edition, Handbook of Optical Constants of Solids, Academic Press Nakamura Shunsuke, Kai Takashi, "Study on coupled radiation / heat conduction analysis of ceramic tile insulation materials," Aerospace Laboratory Report, NAL-TR-1470, August 2003 Japan Society of Thermophysical Properties, "New Edition of Thermophysical Properties Handbook", Yorikendo, April 2008, p. 747

  As described above, conventionally, as the heat insulating coating film or the paint, those containing fine particles or hollow fine particles in the base have been proposed, but none of them show a sufficient heat transfer suppressing effect . Conventional heat insulating coatings or paints do not have a very high proportion of fine particles or hollow particles in the dry coating. This is because if the proportion of the fine particles or hollow particles is increased, the strength of the coating decreases and it becomes difficult to maintain the state of the layer, and it becomes difficult to laminate on the structure. For this reason, the coating film can not be made thick enough, and in the case of a thin coating film, the heat given to the surface reaches the back surface.

  Therefore, in the conventional proposal, in order to provide high thermal insulation even if thin as it is used as a heat insulating coating film or paint, measures have been made to reduce the thermal conductivity. Specifically, the thermal conductivity of the heat insulating coating or the whole of the coating has been reduced by increasing the proportion of fine particles or hollow fine particles having a low thermal conductivity contained in the base. However, as a result, heat transfer due to heat radiation in the heat insulating coating or paint is increased, so that the thickness of the heat insulating coating or paint needs to be a certain thickness or more.

  In the present invention, when heat energy is applied to the surface, the temperature of the surface rises rapidly, and far-infrared radiation from the deep part of the thin film to the surface direction (same as "thermal radiation", hereinafter far- When the meaning of light is strong, the term “far infrared radiation” is used, and when the meaning of energy transport is strong, the term “heat radiation” is used. The purpose is to provide a thin film structure having the feature that most of the thermal energy given to the surface does not reach the back surface by effectively performing heat transfer to the deep part by effectively performing I assume. Such a thin film structure, even with a thickness of several hundreds of micrometers, has the same heat insulating performance as a heat insulating material of about several mm.

  In order to achieve this purpose, the inventors of the present invention change the temperature in the non-steady state taking into consideration not only the depth at which the heat radiation from the surface of the thin film structure occurs and the decrease in the thermal conductivity but also the volume specific heat. Attention was paid to the heat penetrability which shows the ease of operation. As a result, a temperature rise is rapidly generated in the surface layer at a depth which is about the depth to which thermal radiation reaches when heat is applied to the surface (that is, the depth at which thermal radiation is generated from the surface). It has been found that heat transfer to the inside of the thin film structure is suppressed even with a thickness of about 100 μm by utilizing thermal radiation to the surface layer among the radiation. As means for achieving such heat transfer suppression, (a) the distance of far infrared radiation within the thin film structure is short, and (b) the heat conductivity and the volume specific heat are reduced, that is, the heat penetrability By making the surface temperature rise quickly, the amount of heat radiation from the surface to the outside is large, and as a result, a thin film structure having a high heat transfer suppressing effect is obtained. Such a thin film structure is a thin film structure obtained by making the penetration depth of light and the heat permeability as small as possible.

  Here, the "heat transfer suppressing effect" refers to an effect of reducing the amount of heat transferred to the back by a part of the heat entering from the surface of the substance being returned by the heat radiation to the space on the surface side. In the heat insulating paint, "insulation" and "insulation" represent different concepts. The conventional “heat insulation” refers to the amount of heat that flows from the high temperature part to the low temperature part when there is a temperature difference on both sides of the substance (or gas or liquid on both sides of the substance). , The material will be highly adiabatic. Also, “thermally insulating” refers to the heat transfer by radiation (including short wave and long wave), the radiation property is returned to the outside by the reflection property of the substance, and the absorption amount is reduced to reduce the depth of the substance. Say the characteristic that heat does not move.

  More specifically, the thermal radiation generated in the hot side surface layer of the material is directed towards the deep side of the substance as well as towards the hot side surface of the substance. Thermal radiation to the deep side of the material increases the heat transfer inside and results in incorporation in the quantity expressed as thermal conductivity. On the other hand, although the heat radiation to the surface side is partially absorbed by the substance, the remainder reaches the surface of the substance and contributes to the heat transfer to the outside. This phenomenon leads to the heat transfer from the substance to the outside to reduce the amount of heat transfer from the outside to the substance, and as a result, the heat transfer is suppressed.

In a first aspect, the present invention provides a thin film structure used alone or laminated on at least one surface of a substrate. The thin film structure includes hollow fine particles containing a metal oxide and a base in a solidified state. The hollow particles are densely distributed in the base from one surface to at least a first position in the depth direction. When thermal energy (thermal radiation) is irradiated to the surface of the thin film structure, temperature rise in the vicinity of the surface due to absorption of the thermal radiation in the vicinity of the surface causes far infrared radiation from near the surface of the thin film structure to Although the intensity increases, the position of the deepest part where the far infrared radiation is generated is at a second position smaller than the distance from the surface to the first position. The heat permeability of this thin film structure is less than 500 J / (m ² · s ^0.5 · K).

  In general, heat transfer appears in three forms: thermal radiation, thermal conduction and convection. Among the thermal energy given to the surface of the thin film structure, the magnitude of the thermal energy that moves the structure to reach the back surface is determined by the state of thermal radiation and thermal conduction. For example, when the thermal energy applied to the surface reaches the back surface through the thin film structure and is emitted, part of the thermal energy applied to the surface is the surface opposite to the surface by thermal radiation or thermal conduction. It will be moving up to.

  In the thin film structure according to the present invention, the thermal energy given to the surface by the thermal radiation and the convective heat transfer is diffused to the inside by the thermal radiation and the thermal conduction. To be sufficiently scattered by the densely distributed hollow particles from the surface to at least the first position (i.e., the thermal radiation is sufficiently scattered from the surface to the first position) , Hollow particles are densely distributed). Here, "densely distributed" means that the hollow particles are continuously present in the base with almost no gap, and the proportion of the hollow particles in the base in the solidified state is a thin film At least about the first position in the depth direction from the surface of the structure, the state of about 80% by volume or more. As described above, since the hollow fine particles are densely distributed in the base, the heat radiation given to the surface of the thin film structure is mostly scattered by the hollow fine particles. The amount of scattering decreases exponentially from the surface of the thin film structure in the depth direction, and the position of the deepest portion where scattering occurs is a second position where the distance from the surface is smaller than the distance to the first position It becomes. Therefore, the thermal radiation given to the surface is mostly absorbed or scattered at a position shallower than the second position, and the absorbed component contributes to the increase of the surface temperature.

  On the other hand, when thermal energy including thermal radiation and convective heat transfer is given to the surface, the thermal energy absorbed by the base or the hollow fine particles causes a temperature rise near the base surface, and the temperature rise Only the amount of far infrared radiation from the surface is increased. The increase in the amount of far infrared radiation is emitted with the position of the deepest portion where the scattering occurs, that is, the second position as the deepest portion. In other words, far-infrared radiation is emitted from a position shallower than the second position in the depth direction, and does not reach the surface if emitted from a position deeper than the second position, that is, as a result It will not be emitted. Thermal radiation from the vicinity of the surface occurs in both the surface direction and the deep direction, but thermal radiation generated in the deep direction does not reach the surface, and is absorbed in the deep portion of the thin film structure. Therefore, when thermal energy is given to the surface, the temperature distribution is determined by the balance between the radiation from the vicinity of the surface and the heat conduction to the inside, but when the thermal penetrance is small, the thermal radiation to the outside occurs efficiently. As a result, the temperature gradient inside the thin film structure becomes gentle. This reduces the heat energy reaching the deep part and consequently reduces the amount of heat energy reaching the back surface.

  Further, in the thin film structure according to the present invention, since the hollow fine particles containing air are densely distributed, the heat conductivity as a whole is low and the density is small. Therefore, the thin film structure has the property that the volume specific heat is small. Thus, as a result of the nature of low thermal conductivity and low volume specific heat, the thin film structure has a low thermal penetrability, so that it quickly follows the temperature change of the air in contact with the surface and the thermal radiation and the surface. The temperature will go up and down. Therefore, when thermal energy is applied to the surface, the temperature of the surface changes before the temperature of the deep portion changes, and thermal radiation is efficiently generated from the surface to the external space. This reduces the heat energy reaching the deep part and consequently reduces the amount of heat energy reaching the back surface.

The hollow fine particles contained in the thin film structure according to the present invention contain a metal oxide, and as the metal oxide, aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), ferric oxide (Fe ₂₎ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), titanium oxide (TiO ₂ ), cerium oxide (CeO ₂ ), silicon dioxide (SiO ₂ ) or antimony trioxide (Sb ₂ O ₃ ) It is preferable that it contains any or the combination of these.

  In one embodiment, the distance from the surface of the thin film structure to the second position in the depth direction is preferably 20 μm or less. Thus, a thin film structure can be realized because the deepest part of the far infrared radiation is located at a shallow position from the surface of the thin film structure.

  In one embodiment, it is preferable that the wavelength of the far infrared radiation emitted when the surface is irradiated with thermal energy be 5 μm to 30 μm. The wavelength range of 5 μm to 30 μm theoretically contains 88% of thermal radiation from a black body near room temperature (300 K (27 ° C.)), and if the emissivity in this wavelength region is high, room temperature Thermal radiation will be generated efficiently in the vicinity. Therefore, the thin film structure according to the present invention exerts an effective heat transfer suppressing effect as long as it emits far infrared radiation having a wavelength of 5 μm to 30 μm.

  In a second aspect, the present invention provides a structure in which the thin film structure according to any one of claims 1 to 5 is laminated on the surface. In a third aspect, the present invention provides a laminate in which the thin film structure according to any one of claims 1 to 5 is laminated on a substrate. The thin film structure according to the present invention may be used alone as a laminate on the surface of the structure, or on one or both surfaces of various substrates such as wood, metal, tape, resin, etc. It is also possible to laminate and use the laminate of the thin film structure and the substrate thus obtained on the surface of the structure. As a preferable structure which laminates | stacks the thin film structure which concerns on this invention, a building structure, a motor vehicle, a railway vehicle, and a ship can be mentioned.

  When the thin film structure according to the present invention is stacked on the boundary between the inside and the outside of the structure, the transfer of thermal energy from the inside or outside heat source to the outside or inside can be suppressed. The internal environment of the structure can be maintained at a constant state. In particular, when the thin film structure according to the present invention is laminated on the outer wall and / or the inner wall of a building, the air conditioning energy of the building can be reduced throughout the year, and an extremely high energy saving effect can be realized. In addition, when the thin film structure according to the present invention is stacked on, for example, a wall of a room and a heat source is provided in the room, an effect that the temperature of the room rises in a short time can be obtained. This is because the far infrared radiation from the thin film structure to the indoor side increases and heat is less likely to penetrate deep into the thin film structure, so the thermal energy given to the thin film structure efficiently returns to the indoor side. It is. Furthermore, since the thin film structure according to the present invention has a high ability to emit far infrared radiation from the vicinity of the surface, the room comfort is enhanced by the effect of radiation from the part identified with the surrounding temperature by convective heat transfer. To contribute.

Fig. 6 shows a cross-sectional picture of a thin film structure according to an embodiment of the present invention. The top view photograph of the thin film structure shown by FIG. 1 is shown. The setting conditions of preset temperature with the passage of time and preset solar radiation amount in the model test for verifying the heat transfer inhibitory effect of the thin film structure by one embodiment of the present invention are shown. 6 shows a heat transfer suppression effect of a thin film structure according to an embodiment of the present invention. Fig. 6 shows a calculation model of a simulation regarding the heat transfer suppressing effect of the thin film structure according to one embodiment of the present invention. The simulation results are shown.

Hereinafter, the present invention will be described in detail.
[Properties of thin film structure]
The thin film structure according to the present invention comprises a base in a solidified state and hollow fine particles containing a metal oxide. The thin film structure according to the present invention has the following properties.

(1) The hollow fine particles are densely distributed In the thin film structure according to the present invention, the hollow fine particles exist "densely" in the base from the surface of the structure to at least a first position in the depth direction. ing. The thermal energy given to the surface by thermal radiation and convective heat transfer diffuses inside by thermal radiation and thermal conduction, and for the thermal radiation component thereof, the densely distributed hollow from the surface to at least the first position Scattered by particles. The content of hollow particles is preferably about 80% by volume or more and less than about 95% by volume from the surface to at least the first position. If the content is less than about 80% by volume, sufficient heat radiation scattering effect is not exerted, and the heat penetrability does not decrease. When the content is 95% by volume or more, the base can not stably hold the hollow fine particles, and there is a possibility that the thin film can not be maintained in a state where the function of the thin film structure can be exhibited. . The first position is equal in one embodiment to the thickness of the thin film structure and in another embodiment smaller than the thickness of the thin film structure. FIG. 1 shows a cross-sectional photograph of a thin film structure according to an embodiment of the present invention. The thin film structure of FIG. 1 has a thickness of about 270 μm to about 300 μm, and it can be seen from FIG. 1 that the hollow fine particles are densely distributed throughout the thickness.

(2) Shallow position of far infrared radiation The thin film structure according to the present invention is characterized in that the position of the deepest portion where thermal energy absorbed by the base or the hollow fine particles is emitted as far infrared rays is shallow. Thus, the location of the far infrared radiation (or thermal radiation) is shallow, and the surface temperature tends to be higher than the deep temperature when thermal energy is applied to the surface of the thin film structure (this is because Due to the interaction with the low permeability, which is considered to be a feature, much of the far-infrared radiation is generated from a location close to the hotter surface, and consequently only towards the heat source, as a result Much of the thermal energy imparted to the surface does not travel to the back of the thin film structure. In the thin film structure according to one embodiment of the present invention, far infrared radiation is generated from a position shallower than 20 μm from the surface of the thin film structure.

  The thin film structure preferably emits a far infrared wavelength of 5 μm to 30 μm at room temperature of 300 K (27 ° C.). Theoretically, Plank's radiation law representing the amount of radiation from a unit surface of a black body and Stephane-Boltzmann's law obtained by integrating Planck's radiation law over the entire wavelength range, a wavelength of 5 μm at a temperature of 300 K The amount of radiation in the wavelength range between -30 μm is about 88% of the amount of radiation over the entire wavelength range. Therefore, as long as the thin film structure according to the present invention emits far infrared light having a wavelength of 5 μm to 30 μm, an effective heat transfer suppressing effect is exhibited.

(3) The heat permeability is small (volume specific heat and thermal conductivity are small)
The thin film structure according to the present invention is characterized in that the heat transfer rate is small and the density is small because the hollow fine particles containing air are densely distributed, and the volume specific heat is small. As a result, the thin film structure has the advantages of low thermal effusivity, low thermal energy reaching the deep portion, and reduced thermal energy reaching the back surface. Specifically, the heat permeability of the thin film structure according to the present invention is less than 500 J / (m ² · s ^0.5 · K). The thermal permeability Te is an index representing the easiness of temperature change in unit volume in non-stationary heat conduction, and is expressed by the following equation.
Te ² = Tc × ρC
Here, Tc represents thermal conductivity, ρ represents density, C represents specific heat, and CC represents volumetric specific heat.

(4) The difference between the refractive index of the hollow particles and the refractive index of the base is large In the thin film structure according to the present invention, the difference between the refractive index of the base and the refractive index of the hollow particles is large. The hollow particles include aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), ferric oxide (Fe ₂ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), titanium oxide (TiO ₂ ) ₂ ) preferably containing any one or a combination of cerium oxide (CeO ₂ ), silicon dioxide (SiO ₂ ) or antimony trioxide (Sb ₂ O ₃ ), but some of these metal oxides The refractive index can be found in Non-Patent Document 1. According to this, in the wavelength region of 5 μm to 25 μm, especially in the vicinity of 10 μm which is the peak wavelength of black body radiation in the vicinity of room temperature, the complex refractive index largely fluctuates depending on the wavelength due to lattice vibration, and There is a wavelength range where the refractive index difference is large. In the wavelength region, reflection and scattering easily occur at the interface between the metal oxide and the base, and as a result, the penetration depth of the infrared radiation from the surface becomes shallow and the deepest portion where the infrared radiation is generated The position gets shallow. The difference in refractive index is preferably greater than 0.5 at at least one point between the wavelengths 8 μm and 13 μm.

(5) Large surface area The thin film structure according to the present invention is a surface having a large surface area, since the hollow fine particles are densely distributed from the surface to at least the first position and the hollow fine particles appear on the surface. ing. This is also apparent from the plan view of the thin film structure shown in FIG. Therefore, the far infrared radiation emitted inside the thin film structure is characterized by being efficiently emitted from the surface to the outside of the thin film structure, and the heat transfer by convective heat transfer is also efficiently generated. Have.

  The thickness of the thin film structure according to the present invention is preferably 50 μm to 50 mm. With a thin film structure thinner than 50 μm, the effect of heat transfer suppression can not be sufficiently obtained. On the other hand, thin film structures thicker than 50 mm are less cost effective.

[Configuration of thin film structure]
The configuration of the thin film structure according to the present invention will be described below.
(Base)
The thin film structure according to the present invention is obtained by drying and curing a thin film raw material obtained by mixing hollow fine particles with a liquid base (hereinafter referred to as liquid base), and the liquid base is cured. The hollow fine particles are present in the base in the solidified state, which is a portion where the hollow particles are present. The liquid base is obtained by adding the resin, water and various additives and sufficiently stirring.

  The liquid base contains resin, water, if necessary, pigment, hollow particle stabilizer, hollow particle leveling agent, ultraviolet light absorber, thickener, dispersing agent, antifoaming agent, wetting agent, leveling agent, It is obtained by adding an additive such as a coalescent and the like, and sufficiently stirring and mixing. As a specific example of resin which can be used in this invention, an acrylic resin, an epoxy resin, a polyurethane resin, a vinyl chloride resin, a silicone resin, a fluorine resin etc. can be mentioned, for example. The resin is preferably a resin emulsion. As a resin emulsion, an acrylic resin emulsion, an acrylic silicone resin emulsion, a urethane resin emulsion, an epoxy resin emulsion or the like can be used. These resins may be used alone or in any combination of two or more.

  In general, when the content of hollow fine particles is increased, the strength of the thin film structure is reduced, and the lamination property (adhesion) between the thin film structure and the surface on which the structure is laminated is reduced, and application to the surface of the structure It will be difficult to do. Therefore, in order to improve the application to the surface of the structure, it is preferable to increase the flowability of the liquid base. The fluidity of the liquid base can be adjusted by appropriately selecting the type of resin used and the mixing ratio. The mixing ratio of the resin is preferably about 60% by volume to about 70% by volume with respect to 100% by volume of the liquid base.

In the liquid base, it is preferable to mix a hollow particle stabilizer in order to stabilize the arrangement of the hollow particles contained when dried. Fine particles smaller than the average particle size of the hollow fine particles can be used as the hollow fine particle stabilizer. Such fine particles are more preferably fine particles that simultaneously provide a heat shielding effect. As such fine particles, for example, fine particles of carbon fine particles or titanium oxide (TiO ₂ ) can be used.

  In addition, it is preferable to mix a hollow particle leveling agent so that the hollow particles can be uniformly dispersed in the liquid base. As the hollow particle leveling agent, a component effective for improving the adhesion at the interface between the organic material and the inorganic material, such as a silane coupling agent, can be used.

  Furthermore, in order to prevent deterioration of the base from ultraviolet light, it is preferable to mix an ultraviolet absorber such as a UV-absorbing polymer with the base. Further, for the purpose of imparting algal properties to the thin film structure, it is preferable to mix a substance having an algal effect such as calcium oxide with the base.

  It is preferable to add various additives to the liquid base, if necessary. As additives, known additives such as thickeners, dispersants, antifoaming agents, wetting agents, leveling agents, coalescents and the like can be used. In the present invention, since the amount of the hollow fine particles contained in the base is extremely large, it is necessary to sufficiently stir the hollow fine particles after charging the liquid base. In performing sufficient agitation, the generation of air bubbles is often a problem, so it is preferable to use an antifoam agent at an appropriate timing. In addition, when hollow fine particles are charged into the liquid base, it is preferable to divide and charge the whole amount several times instead of charging all at once.

(Hollow particles)
The hollow particles contained in the thin film structure according to the present invention are hollow particles containing a metal oxide. The hollow fine particles may be uniformly mixed in the liquid base and may be any ones that do not impair the mechanical specification. As a metal oxide contained in hollow particles, for example, aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), ferric oxide (Fe ₂ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ ) ₂ O), titanium oxide (TiO ₂ ), cerium oxide (CeO ₂ ), silicon dioxide (SiO ₂ ) or antimony trioxide (Sb ₂ O ₃ ), or a combination thereof can be used. In the present invention, it is most preferable to use a hollow structure sodium aluminosilicate glass containing these metal oxides as the hollow fine particles.

  The hollow fine particles that can be used for the thin film structure according to the present invention preferably have an average particle diameter of 10 μm to 100 μm, and preferably have a density of 0.05 g / cc to 0.3 g / cc.

  The hollow particles are preferably porous. By using the porous hollow fine particles, the thin film structure has a humidity control function, so that there is an advantage that, for example, when the thin film structure is laminated on the inner wall of a building, the comfort in the room is improved.

[Use of thin film structure]
The thin film structure according to the present invention can be used in any application as long as it is necessary to suppress the heat transfer from one of the boundaries separating the space to the other. The thin film structure may be used alone as a structure, may be used by being laminated on any substrate or on the wall of a structure, or may be used as laminated on the surface of any container. When the thin film structure is used by being laminated on a substrate, examples of the substrate include wood, metal, tape, resin and the like. As a structure which laminates a thin film structure, a building, a car, a rail car, a ship etc. can be mentioned, for example.

Hereinafter, an embodiment of the present invention will be described.
In the present embodiment, aluminum oxide (Al ₂ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O) and titanium oxide (TiO ₂ ) are generally 3: 1: 1 as metal oxides. An aluminosilicate sodium glass containing at a ratio of 1: 1 was used. The content ratio of the main component silicon dioxide (SiO ₂ ) was about 75%. As for the base, the proportions of the components contained in the liquid base before curing were as shown in Table 1.

  The various components shown in Table 1 were prepared, and thoroughly mixed and stirred to obtain a liquid base. By mixing 18 parts by weight of the above-mentioned sodium aluminosilicate glass (hollow fine particles) with 100 parts by weight of the base in the liquid state, a thin film raw material in a liquid state containing hollow fine particles was obtained. The content ratio of hollow fine particles at this time was 60% by volume. The thin film raw material thus obtained was applied to a substrate such as a wall or a metal plate of a building and dried to obtain a thin film structure having a hollow fine particle content of 80% by volume. In addition, since the content of the hollow fine particles is large, the thin film raw material loses its smoothness in a short time and can not be applied to the substrate. Therefore, at the time of application, the thin film raw material was appropriately diluted with ethanol, the base was made smooth, and the hollow fine particles were appropriately dispersed in the base to apply the base. When it is necessary to obtain a thin film structure by applying thin film raw materials as needed, it is preferable to carry out while adding ethanol as needed for each coating. Ethanol does not remain in the finally obtained thin film structure because it volatilizes in the process of drying. The thin film structure having a content of hollow fine particles of greater than 80% by volume is obtained by appropriately designing the amount of hollow fine particles to be mixed with 100 parts by weight of the base so as to finally obtain the required content. be able to.

(Thermal physical properties of thin film structures)
Table 2 shows the comparison of the thermophysical property value in 25 degreeC about the thin film structure (Example) which concerns on this invention, and the heat insulation coating film for a comparison (comparative example). The samples of the examples were obtained by applying the thin film raw material of the thin film structure according to the present invention to copper plates of 1 cm × 1 cm and 5 cm × 5 cm with a required thickness, and drying them respectively. The thickness of the thin film structure after drying was 283 μm, and the content of hollow fine particles was 92% by volume. The thermal diffusivity was measured by a laser flash method using a sample of 1 cm × 1 cm, and the thermal conductivity and the thermal penetrance were derived from the thermal diffusivity. The density required for extraction is measured by measuring the weight and thickness of the sample using a 5 cm × 5 cm sample, and for the specific heat, a differential scanning calorific value using a thin film peeled from the 5 cm × 5 cm sample It measured by the meter.
On the other hand, the comparative example was obtained by apply | coating the heat insulation coating which consists of a component of Table 1 to a 1 cm x 1 cm and a 5 cm x 5 cm copper plate as a raw material component, and making it dry each. The thickness of the coating after drying was 421 μm. The measuring method of the thermophysical property value of a comparative example is the same as that of an Example.

  The thin film structure of the example has smaller density, thermal conductivity and thermal effusivity as compared with the comparative example. Due to this feature, the thin film structure according to the present invention has the property that the temperature of the surface rises rapidly when the surface is irradiated with thermal energy. In addition, the thin film structure according to the present invention has a small volume specific heat because the thermal conductivity and the density are small, and as a result, the thermal energy reaching the deep portion decreases and the thermal energy reaching the back surface decreases. It also has the nature.

Table 3 shows the comparison of the thermophysical properties when the content of hollow fine particles is changed in the thin film structure. The measuring method of the thermophysical property value of each sample shown in Table 3 was the same as that of the example of Table 2. In Table 3, CG50 is a sample having a hollow fine particle content of 50% by volume, and similarly, CG70 and CG80 are data of 70% by volume and 80% by volume, respectively. In addition, CG91 and CG92 are both samples having a content of 90% by volume. It can be seen that the thin film structure having a hollow fine particle content of 80% by volume or more has a heat permeability lower than 500 J / (m ² · s ^0.5 · K).

(Model test on heat transfer suppression effect)
The model test equipment was used to demonstrate the heat transfer suppression effect of the wall laminated with the thin film structure according to the present invention. Specifically, an indoor environment (indoor room) and an outdoor environment (outdoor room) are constructed using artificial weather equipment manufactured by Marui Corporation, and a thin film structure is formed on the outdoor room side of the wall separating the indoor room and the outdoor room. The amount of infrared radiation (W / m ² ) was measured with and without laminating. The amount of infrared radiation was measured by an infrared radiometer installed on the outdoor room side. As a wall which separates an indoor room and an outdoor room, a rustproofed iron plate (example) which laminated a thin film structure, and a rustproofed iron plate (comparative example) which does not laminate a thin film structure were used. In addition, the iron plate of an Example and the iron plate of a comparative example are the same. The size of the iron plate was 1 m × 1 m, the thickness was 1 mm, and the thickness of the thin film laminate was 400 μm.

The artificial weather system was operated with the following program. FIG. 3 shows the elapsed time of the preset temperature and the preset solar radiation amount set in the following program.
(Winter season assumed)
a. After stabilizing both the outdoor and indoor rooms at a temperature of 10 ° C., raise the temperature of the indoor room to 30 ° C. b. After the temperature of the indoor room is lowered to 10 ° C. and stabilized, the outdoor room is irradiated with 95 W / m ² of solar radiation c. After the irradiation was stopped and stabilized, the outdoor room was irradiated with 515 W / m ² of solar radiation d. Stop irradiation and stabilize (assuming in summer)
e. Both the outdoor room and the indoor room are stabilized at a temperature of 30 ° C., and then the indoor room is cooled to 10 ° C. f. After raising the temperature of the indoor room to 30 ° C. and stabilizing it, irradiate 95 W / m ² of solar radiation to the outdoor room g. After the irradiation was stopped and stabilized, the outdoor room was irradiated with 515 W / m ² of solar radiation h. After the irradiation was stopped and stabilized, the temperature of the room was lowered to 10 ° C., and simultaneously 515 W / m ² of solar radiation was irradiated i. Stop irradiation and stabilize

  FIG. 4 is a figure which shows the heat transfer inhibitory effect of the thin film laminated body by the result of this model test, and, specifically, shows the change of the measured value of the infrared radiation amount with progress of test time. Infrared radiation is radiation to the outdoor room side from the wall separating the indoor room and the outdoor room. "Heating", "cooling", and "solar radiation" in the figure respectively indicate the temperature setting assuming a heating state, the temperature setting assuming a cooling state, and the time of heat energy irradiation by sunlight or a human body. The amount of infrared radiation was corrected by using the temperature of the infrared radiometer itself and the measured value of the infrared radiometer.

From FIG. 4, the heat transfer suppressing effect of the thin film structure can be described as follows.
(1) Elapsed time around 2 hours (time of operation of the above program a), around 12 hours (time of operation of the above program e) and after 18 hours (time of operation of the above program h) Although the infrared radiation amount increases in the comparative example with respect to the rise and fall, the infrared radiation amount does not change in the example. From this, it can be seen that in the case of the embodiment, the temperature change in the indoor chamber does not affect the outdoor chamber side, and the wall of the embodiment has a heat transfer suppressing effect.

(2) Elapsed time around 4 hours (time of operation of program b), around 7 hours (time of operation of program c), around 14 hours (time of operation of program f), around 17 hours (above program At the time of operation g) and around 19 hours (at the time of operation h of the above program h), the infrared radiation amount of the example is larger than the infrared radiation amount of the comparative example. This is because, in the case of the example, the heat conductivity of the wall is low, and the temperature of only the surface of the wall rises rapidly at the time of solar radiation and heat is not transmitted to the deep part. As a result, the infrared radiation from the wall surface It is thought that the amount is increasing.

(3) The superiority of the wall of the embodiment (that is, the wall on which the thin film structure according to the present invention is applied) in terms of the comfort of the indoor environment and the effect on the heating and cooling load is explained as follows. can do.
(A) According to the result of around 2 hours of elapsed time, in the case of the wall of the embodiment, heating heat is difficult to escape from indoors to outdoor during winter heating, so that the heating efficiency becomes high and heating load can be reduced. I understand.

(A) The result of heating in winter can be considered to be the effect of cooling in summer when the thin film structure is installed on the indoor room side by changing the position of the indoor room and the outdoor room. Therefore, according to the result of around 2 hours of elapsed time, in the case of the wall of the example, it can be seen that the radiant heat from the wall to the indoor room side during cooling in summer is small and the indoor comfort can be maintained. .

(C) The result of the solar radiation irradiation in the vicinity of 4 hours of elapsed time can be considered as an effect when there is a human body or some other heating element on the indoor side when the thin film structure is installed on the indoor side. Therefore, from the results near 4 hours of elapsed time, the amount of infrared radiation from the wall induced by infrared radiation from the human body or any other heating element is larger in the example than in the comparative example. It can be seen that reducing the heating load is possible by using

(D) From the result of around 12 hours elapsed time, in the case of the wall of the embodiment, the heat of the outdoor side during cooling in summer is hard to move to the indoor side, so that the cooling efficiency becomes high and the cooling load is reduced. It turns out that it is possible.

(E) As in the case of (A) above, the result of cooling in summer is the effect of heating in winter when the thin film structure is constructed on the indoor room side by replacing the positioning of the indoor room and the outdoor room I can think of it. Therefore, from the results of around 12 hours of elapsed time, in the case of the wall of the example, it can be understood that the heat radiation from the wall to the indoor room side is large at the time of heating in winter and the indoor comfort can be maintained. .

(Simulation about the heat transfer suppression effect)
Computer simulation was conducted to show that the thin film structure according to the present invention has a heat transfer suppressing effect. In the simulation, using the physical property values of the sample of "CG91" shown in Table 3 as an example of the thin film structure according to the present invention, and using the physical property values of the sample of "CG50" shown in Table 3 as a comparative example. . As a calculation method, the amount of heat passing through the thin film structure having a thickness of 1 mm was determined by computer simulation using an equation given by a two flux method based on a radiation transfer equation. The radiation transport equation and the two flow velocity method can be known, for example, by Non-Patent Document 2. The calculation model used is shown in FIG. Table 4 shows physical property values of the thin film structures CG50 and CG91 used for the simulation. The hollow fine particle content of CG50 and CG91 is 50% by volume and 90% by volume, respectively. The temperature of the front air layer of the sufficiently large thin film structure was assumed to be 20 ° C. (293 K), and the temperature of the back air layer was 0 ° C. (273 K). In addition, in order to secure a sufficient heat flow, it was assumed that infrared radiation of 200 (W / m ² ) was incident from the front air layer and all was absorbed.

The meaning of each symbol of the calculation model shown in FIG. 5 is as follows.
T _H : Temperature of the front air layer of the thin film structure T _L : Temperature of the back air layer of the thin film structure K _eH : Attenuation coefficient of the front side of the thin film structure (sum of absorption coefficient and scattering coefficient. See Non-Patent Document 3) The reciprocal corresponds to the penetration depth of infrared radiation (the second position), which is shown as the reciprocal _{Ke H} ^-1 to represent the penetration depth in FIG.
K _eL : Attenuation coefficient on the back side of the thin film structure (in the same manner as K _eH , it is shown by the inverse number K _eL ^-1 in order to indicate the penetration depth in FIG. 5. The penetration depth on the back side was a fixed value 30 μm )
Q _in: infrared radiation quantity incident from the front side air layer into the film structure surface I ^+: toward the front direction of the film structure infrared radiation quantity I ^-: infrared radiation quantity I _IRH toward the rear direction of the film structure : Infrared radiation amount incident on the surface from the front side air layer of the thin film structure with the air layer as a heat source I _irL : Infrared radiation amount incident on the back surface of the thin film structure from the back air layer to the back surface with the air layer as a heat source Z _SH : Position on the front side of the thin film structure Z _SL : Position on the back side of the thin film structure Q _cH : Heat quantity transferred by convection on the front side of the thin film structure Q _cL : Convection on the back side of the thin film structure Of heat transferred by heat Q _tot : heat transferred in thin film structure

The simulation results are shown in FIG. The horizontal axis of FIG. 6 is the deepest part (that is, corresponding to the second position) of the far infrared radiation, and the vertical axis is the amount of heat passing through the thin film structure. From this result, the following can be understood.
(1) Regardless of the second position, CG91 has a smaller amount of heat transferred to the back surface of the thin film structure than CG50. This is due to the difference in thermal conductivity or thermal effusivity of the thin film structure, and a difference of about 3.5% can be seen overall.
(2) In both CG 50 and CG 91, the amount of heat transferred is largely changed at a position of about 20 μm, and the amount of heat transferred to the back surface of the thin film structure is smaller at positions smaller than that position. This means that the position of the deepest part of far infrared radiation is more preferably 20 μm or less.

Claims (7)

A thin film structure exhibiting a heat transfer suppressing effect, which is used alone or laminated on at least one surface of a substrate,
Containing hollow fine particles containing metal oxide and a base in a solidified state,
The hollow particles are densely distributed in the base material from one surface of the thin film structure to at least a first position in the depth direction,
The position of the deepest part of far infrared radiation when thermal energy is irradiated to the surface exists at a second position smaller than the distance from the surface to the first position,
Thermal permeability is less than 500 J / (m ² · s ^0.5 · K),
A thin film structure having thermal characteristics satisfying the conditions.   The thin film structure according to claim 1, wherein a content of the hollow fine particles is at least 80% by volume at least from the surface to the first position. The metal oxides include aluminum oxide (Al ₂ O ₃ ), magnesium oxide (MgO), ferric oxide (Fe ₂ O ₃ ), sodium oxide (Na ₂ O), potassium oxide (K ₂ O), and titanium oxide The thin film according to claim 1, characterized in that it is (TiO ₂ ), cerium oxide (CeO ₂ ), silicon dioxide (SiO ₂ ) or antimony trioxide (Sb ₂ O ₃ ), or a combination thereof. Structure.   The thin film structure according to claim 1, wherein the second position is a position not more than 20 μm from the surface.   The wavelength of radiation by the far infrared radiation is 5 to 30 μm.   A structure in which the thin film structure according to any one of claims 1 to 5 is laminated on the surface.   The laminated body on which the thin film structure in any one of Claims 1-5 was laminated | stacked on the base material.