Sheet-like device with heat storage function

Abstract

To provide a sheet-like device having a heat storage function suitable for a heating device capable of heating or warming with a low power consumption.SOLUTION: There is provided a sheet-like device 10 including a sheet-like substrate 13, a resin-made heat storage layer 15 laminated on the substrate directly or via another layer and containing a plurality of hollow particles containing gas, and a highly rigid resin-made first shell layer 11 laminated on the resin layer directly or via another layer. The hollow particles may include hollow resin beads, and the heat storage layer 15 may further include a plurality of metal particles 55.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sheet-like device with a heat storage function. [Background technology]

[0002] Patent Document 1 discloses a heat insulating coating film that can provide excellent heat insulating performance and far-infrared reflective performance when formed on the surface of an exterior or interior wall of a house, and that also has excellent adhesion and durability. This heat insulating coating film contains a styrene-acrylic acid alkyl ester copolymer or a butyl acrylate-styrene copolymer, a white pigment, and hollow acrylic beads, and is characterized in that the mass ratio of the hollow acrylic beads to the styrene-acrylic acid alkyl ester copolymer or butyl acrylate-styrene copolymer (hollow acrylic beads / styrene-acrylic acid alkyl ester copolymer or butyl acrylate-styrene copolymer) is 1 or less.

[0003] Patent Document 2 describes the provision of a thermal insulating coating composition that can form a coating film that has sufficient adhesion to a substrate and excellent thermal insulating properties. The thermal insulating coating composition contains, relative to the total amount of the coating composition, an aqueous emulsion of an acrylic acid ester-methacrylic acid ester-styrene copolymer or an acrylic acid ester-styrene copolymer in the range of 35 to 50 mass %, rutile titanium dioxide in the range of 20 to 30 mass %, and acrylic hollow beads in the range of 5 to 20 mass %. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. WO2017 / 099171 [Patent Document 2] Japanese Patent Publication No. 2023-80555 Summary of the Invention [Problem to be solved by the invention]

[0005] The coating films described in Patent Documents 1 and 2 are known as coating films containing hollow beads and having high heat insulation properties. Meanwhile, there is a demand for a sheet-shaped device with a heat storage function suitable for a heating device that can heat or warm up with low power consumption. There is also a demand for a thin, sheet-shaped heating device with the heat storage function. [Means for solving the problem]

[0006] One aspect of the present invention is a sheet-like device having a sheet-like substrate, a resin-made heat storage layer laminated to the substrate directly or via another layer and containing a plurality of hollow particles containing a gas, and a first shell layer made of a highly rigid resin laminated to the resin layer directly or via another layer. In this device, the highly rigid first shell layer suppresses volumetric expansion of the hollow particles when the heat storage layer is heated. Therefore, at least a portion of the energy used to heat the heat storage layer is retained (stored) as internal energy of the gas, increasing the pressure of the gas contained in the hollow particles. Furthermore, the heat storage layer has a structure with high thermal insulation properties and low thermal conductivity and heat transfer coefficient. Therefore, a sheet-like device with high heat storage capacity can be provided even if the heat storage layer is thin.

[0007] The hollow particles may include resin hollow beads. The hollow particles may be hard hollow particles such as glass beads or ceramic beads, but these are prone to breaking due to impact, bending, or other shape changes. Hollow particles made of resin such as acrylic beads can be given moderate elasticity, making them less susceptible to impact and shape changes, providing a device that is highly reliable and easily maintains its heat storage capacity. The heat storage layer may contain multiple metal particles. By mixing a material with a high specific gravity (metal particles) with a material with a low thermal conductivity (hollow particles), the temperature transfer rate (thermal diffusivity) can be reduced, providing a device with a higher heat storage effect.

[0008] One example of a sheet-like device is a heat storage device that does not include a heating function, and the sheet-like substrate may be a second shell layer made of a highly rigid resin. Another example of a sheet-like device is a device that includes a heating function, and the sheet-like substrate may include a sheet-like heating element (sheet heater). The sheet-like heating element may have enough rigidity to inhibit expansion of the heat storage layer. The sheet-like device may include a second shell layer made of a highly rigid resin, laminated directly or via another layer on the opposite side of the first shell layer across the sheet-like heating element. A layer containing aggregate may be provided at least between the heat storage layer and the first shell layer and between the second shell layer and the first shell layer. This can strengthen the rigidity of the first shell layer and / or the second shell layer, further inhibit expansion of the heat storage layer, and improve the strength of the device. In addition, the shape of the aggregate may be exposed through the shell layer, adding other functions to the device, such as anti-slip properties. The heat storage layer may be a layer coated with a heat insulating paint containing hollow particles, and the first shell layer may be a layer coated with a paint containing a urethane resin or a polyurea resin.

[0009] Another aspect of the present invention is a heating device that includes a sheet-like device including a sheet-like heating element and a control device that controls the power supplied to the sheet-like heating element. Utilizing the heat storage function of the sheet-like device, a device that can heat or warm a wide area with low power consumption can be provided.

[0010] Another aspect of the present invention is a method for manufacturing a sheet-like device, comprising: forming a heat storage layer made of a resin containing a plurality of hollow particles containing a gas directly on a sheet-like substrate or via another layer; and forming a first shell layer made of a highly rigid resin directly on the resin layer or via another layer. Forming the heat storage layer may include forming the heat storage layer from a resin containing a plurality of hollow particles and a plurality of metal particles. The sheet-like substrate may include a sheet-like heating element, and forming a second shell layer made of a highly rigid resin directly or via another layer on the opposite side of the sheet-like heating element from the first shell layer. Forming a layer containing an aggregate between the heat storage layer and the first shell layer or between the second shell layer and the heat storage layer may include applying a heat insulating paint containing resin hollow beads as the hollow particles, and forming the first shell layer may include applying a paint containing a urethane resin or a polyurea resin. [Brief explanation of the drawings]

[0011] [Figure 1] 1 shows an example of a heating system including a snow melting mat. [Figure 2] The area including the heat storage layer of the snow melting mat is shown enlarged. [Figure 3] The results of measurements using a snow-melting mat are shown in Figure 3(a), where a simple measurement method is shown, and Figure 3(b) shows an example of the measurement results. DETAILED DESCRIPTION OF THE INVENTION

[0012] FIG. 1 shows an overview of an example of a heating device (heating system) according to the present invention. This heating system 1 is for snow melting and is installed on snowy roads or in areas with heavy snow melting to melt snow and ice and ensure safe passage. The heating system 1 includes a snow melting mat 10 and a control device 20 that controls the power supply to the snow melting mat 10 from a power source 29. The snow melting mat 10 is a sheet-like heating device and includes, stacked in this order from the bottom up, a first shell layer 11, a heat storage layer 15, a sheet-like heating element (heater) that is a sheet-like substrate 13, a primary (primer) layer 17, an aggregate layer 16, and a second shell layer 12. The snow melting mat 10 is typically a thin, rectangular sheet-like device with sides measuring from several centimeters to several tens of centimeters or several meters, and the overall thickness may be approximately 3 to 10 mm, 3 to 5 mm, or 3 to 4 mm.

[0013] The first shell layer 11 and the second shell layer 12 are highly rigid resin layers with a thickness of approximately 1.0 to 1.2 mm, and are typically layers (coatings) formed by applying a polyurea resin by spraying or the like. Polyurea resin is a resin compound based on urea bonds, and has high waterproof and corrosion resistance, chemical resistance, abrasion resistance, impact resistance, high rigidity, and quick drying properties, and is also used as an insulating paint. Polyurea resin is known as a resin that has strength comparable to that of concrete while also possessing the flexibility of a resin. The first shell layer 11 and the second shell layer 12 may be layers primarily made of polyurea resin, or may be hybrid layers of polyurea and urethane. As long as sufficient strength can be maintained, various known materials such as polyurethane, polyamide, polyester, and polycarbonate may also be used.

[0014] The heat storage layer 15 is a resin layer containing a large number of hollow particles containing gas, and its thickness may be about 0.2 to 1.0 mm, about 0.2 to 0.5 mm, or about 0.2 to 0.3 mm. One example is a layer coated with a heat insulating paint known from Patent Documents 1 or 2, which uses an aqueous emulsion of acrylic resin, such as a styrene-acrylic acid alkyl ester copolymer, an acrylate-butylstyrene copolymer, or an acrylic ester-methacrylic ester-styrene copolymer, as a binder, contains acrylic hollow beads as hollow particles, and contains titanium, for example, rutile titanium dioxide, as metal particles.

[0015] FIG. 2 shows a schematic diagram of the heat storage layer 15. The acrylic hollow beads 53 contained in the acrylic resin binder 51 of the heat storage layer (coating) 15 made of the heat insulating paint 50 may have an average particle diameter in the range of 0.2 to 200 μm, or may have an average particle diameter in the range of 10 to 40 μm. With respect to 100 parts by mass of the binder 51, the acrylic hollow beads 53 may be contained in an amount of 5 to 85 parts by mass, 5 to 20 parts by mass (for example, 5 to 20% by mass), or 45 to 85 parts by mass. The acrylic hollow beads 53 may occupy a volume of 60 to 80% by volume of the entire heat storage layer 15. The acrylic hollow beads 53 may be filled with a hydrocarbon gas such as methane, ethane, propane, or butane, or carbon dioxide gas, and as described above, may have the function of storing heat as the internal energy of the gas within the acrylic hollow beads 53, absorbing and storing electromagnetic waves in the far-infrared range, and radiating the stored far-infrared rays. The resin (organic) hollow particles 53 are not limited to acrylic resin hollow particles (acrylic hollow beads) but may also be epoxy resin, silicone resin, fluororesin, etc., but acrylic or acrylonitrile hollow particles 53 are an example of a preferred hollow particle in terms of heat resistance and strength.

[0016] The titanium particles (metal particles) 55 may be contained in an amount of 20 to 150 parts by mass, 20 to 30 parts by mass (for example, 20 to 30% by mass), or 74 to 143 parts by mass relative to 100 parts by mass of the binder 51, and may have an average particle size in the range of 0.1 to 10 μm. The heat storage layer 15 may further contain other materials such as shirasu balloons.

[0017] The sheet-like substrate 13 includes a sheet-like heater 30 that serves as a heat source. An example of the heater 30 is a sheet-like heating element having a thickness of about 0.3 to 1.0 mm, and may have a thickness of about 0.3 to 0.6 mm, or may have a thickness of about 0.3 to 0.4 mm. An example of the sheet-like heating element 30 is a woven fabric heater containing conductive fibers, and may be laminated.

[0018] The primary layer (primer layer) 17 is a layer for improving adhesion between the heater 30 and the layers applied to both sides thereof, and may be provided on one or both sides of the heater 30 (substrate 13). The primary layer 17 may be a layer coated with a primer containing a urethane-based resin, a layer coated with a primer containing an epoxy-based resin, or a layer coated with a primer containing other components.

[0019] The aggregate layer 16 is a layer about 1 mm or less in thickness, and may be provided to improve the strength of the shell layer 11 or 12, or to provide anti-slip irregularities on the surface 10a of the snow-melting mat 10. The particle size of the aggregate may be about 0.3 to 1.7 mm, 0.3 to 1.2 mm, or 0.6 to 1.7 mm. The aggregate may be an anti-slip aggregate, silica sand, or flaked glass fiber.

[0020] As shown schematically in Figure 2, the sheet-like device 10 with heat storage function of this example includes a sheet-like substrate 13, a resin-made heat storage layer 15 that is laminated on the substrate 13 directly or through another layer and contains a plurality of hollow particles 53 containing gas, and a first shell layer 11 made of highly rigid resin that is laminated on the heat storage layer 15 directly or through another layer. In the sheet-like device 10 of this example, the substrate 13 includes a sheet-like heating element 30, and a highly rigid resin-made second shell layer 12 that is laminated on the opposite side of the sheet-like heating element 30 from the first shell layer 11 directly or through another layer. The hollow particles 53 contained in the heat storage layer 15 include hollow resin beads, and the heat storage layer 15 further includes a plurality of metal particles 55.

[0021] The thermal storage layer 15 contains a low-thermal-conductivity gas in hollow beads 53 within a bubble-forming plastic material, and also contains a high-specific-gravity metal material 55. Furthermore, the thermal storage layer 15 is stacked on (contacts) an electrically driven heater 30, which serves as a heat source, and is heated by the heater 30. This causes the temperature of the metal material (metal component) 55 to rise, which in turn causes the temperature within the bubbles in the hollow beads 53 to rise, increasing their internal pressure. In this phenomenon, the hollow beads 53 are sealed on both the top and bottom surfaces by the first shell layer 11 and the second shell layer 12, which are made of highly airtight and insulating materials, and the gas (bubbles) within the hollow beads 53 experience almost no increase in volume, but their internal pressure increases, resulting in a rise in atmospheric pressure. Therefore, the thermal energy supplied by the heater 30 is stored as internal energy of the gas within the hollow beads 53.

[0022] Furthermore, the heat storage layer 15 of this example is configured by mixing a metal material (metal particles) 55 with a high specific gravity and a material (hollow particles) 53 with a low thermal conductivity, resulting in a low thermal diffusion coefficient. Therefore, even when the heater 30, which is the heat source, is turned off, the temperature of the gas inside the hollow particles 53 of the heat storage layer 15 continues to rise, and the volume of the hollow particles 53 is kept constant, so heat is stored as internal energy of the gas. The internal temperature of the hollow particles 53 continues to rise until the amount of heat passing to the outside equals the amount of heat generated.

[0023] Materials with high specific gravity and specific heat have a heat storage effect by themselves and a large temperature rise. The heat storage layer 15 of the device (snow melting mat) 10 of this example has these characteristics, resulting in a layer with a large heat storage effect overall and low thermal conductivity. Therefore, even a thin film, for example, 0.3 mm thick, can provide a device that can store a large amount of heat. In the device 10 of this example, because the heat storage capacity is large, a snow melting mat can be provided that retains heat for a long period of time, that is, it takes a long time for the temperature to drop.

[0024] As described above, the heating system 1 of this example includes a snow melting mat 10 with long temperature rise and fall characteristics (long time constant). Therefore, the on period of power supplied to the heater 30, which is the heat source of the snow melting mat 10, is shortened, resulting in lower power supply. The control device 20 of the heating system 1 includes a sensor 22 that detects the surface temperature of the snow melting mat 10, a switch 21 that turns the power supply to the heater 30 on and off, and a controller 25 that controls the on and off of this switch 21, and the sensor 22 controls the surface temperature of the snow melting mat 10 to a set temperature or temperature range. In this case, the controller 25 controls the power supply by controlling the pulse width of the on / off period, making it possible to provide a heating system 1 that can achieve maximum effect with minimum power.

[0025] FIG. 3 shows the results of measurements taken by a measuring device 31 using a thermocouple to measure the temperature of the surface (first surface) 41 of the snow melting mat 10 sandwiching the heat storage layer 15 against the heater 30, and the results of measurements taken by a measuring device 32 using a thermocouple to measure the temperature of the surface (second surface) 42 without the heat storage layer. In one example of a measurement using a square snow melting mat 10 measuring 1 m on a side, the heater 30 is turned on at time t0 by supplying 35 V DC from the power supply 29. The temperature of the second surface 42 rises rapidly immediately after the heater 30 is turned on, while the temperature of the first surface 41 begins to rise at time t1, several tens of seconds later. When the heater 30 is turned off at time t2, 300 seconds after time t0, the temperature of the second surface 42 begins to drop at time t3, 220 seconds later, while the temperature of the first surface 41 begins to drop at time t4, 240 seconds later. Therefore, by sandwiching the heat storage layer 15, the thermal diffusion coefficient decreases, the time constant increases, and the temperature retention time increases from T1 to T2, i.e., a heat storage function is obtained. By performing control corresponding to this temperature retention time T2, for example, in the present example system 1 using the snow melting mat 10, it is expected that a power reduction of approximately 50% can be achieved. Furthermore, by using a shell layer with even higher rigidity, a greater power reduction rate can be expected.

[0026] While the present invention has been described above using a snow-melting mat as an example, the sheet-like device of the present invention is not limited to snow-melting mats and may also be a heating device such as a floor heating sheet, and its application is not limited. The snow-melting mat configuration described above is merely an example of the configuration of a sheet-like device. For example, the configuration may be, in order, a heater layer, a primary layer, a heat storage layer, an aggregate layer, and a shell layer. It is sufficient if the heat storage layer containing hollow particles is sandwiched between layers (such as shell layers or heater layers) that have sufficient strength (rigidity) to prevent the hollow particles from expanding. Furthermore, the above discloses a method for manufacturing a sheet-like device, which includes forming the heat storage layer 15 by applying an insulating paint 50 containing hollow resin beads as hollow particles and forming the first shell layer 11 by applying a paint containing a urethane resin or a polyurea resin. However, instead of using paint, each layer may be laminated by other methods such as spraying, vapor deposition, or coating. Alternatively, the sheet-like device may be manufactured by stacking (laminating) layers previously formed into a film or thin film (sheet). [Explanation of symbols]

[0027] 1 Heating system, 10 Sheet-like device including heat storage function (snow melting mat) 20 Control System

Claims

1. A sheet-like substrate; a heat storage layer made of resin, which is laminated on the base material directly or via another layer and contains a plurality of hollow particles containing a gas; and a first shell layer made of a highly rigid resin laminated to the resin layer directly or via another layer.

2. In claim 1, The sheet-like device, wherein the hollow particles include hollow resin beads.

3. In claim 1 or 2, The heat storage layer is a sheet-like device containing a plurality of metal particles.

4. In claim 1 or 2, A sheet-like device, wherein the sheet-like substrate is a second shell layer made of a highly rigid resin.

5. In claim 1 or 2, A sheet-like device, wherein the sheet-like substrate includes a sheet-like heating element.

6. In claim 5, A sheet-like device having a second shell layer made of a highly rigid resin laminated directly or via another layer on the opposite side of the first shell layer with the sheet-like heating element sandwiched therebetween.

7. In claim 6, A sheet-like device having a layer containing aggregate between the thermal storage layer and the first shell layer and / or between the thermal storage layer and the second shell layer.

8. In claim 1 or 2, the heat storage layer is a layer coated with a heat insulating paint containing the hollow particles, A sheet-like device, wherein the first shell layer is a layer coated with a paint containing a urethane resin or a polyurea resin.

9. The sheet-like device according to claim 5; a control device for controlling the power supplied to the sheet-shaped heating element.

10. In claim 9, The sheet-like device is a heating device including a second shell layer made of a highly rigid resin laminated directly or via another layer on the opposite side of the first shell layer with the sheet-like heating element in between.

11. Forming a resin heat storage layer containing a plurality of hollow particles containing a gas on a sheet-like substrate directly or via another layer; and forming a first shell layer made of a highly rigid resin on the resin layer directly or via another layer.

12. In claim 11, The manufacturing method, wherein forming the heat storage layer includes forming the heat storage layer from a resin containing a plurality of metal particles together with the plurality of hollow particles.

13. In claim 11, the sheet-like substrate includes a sheet-like heating element, and forming a second shell layer made of a highly rigid resin, either directly or via another layer, on the opposite side of the sheet-like heating element from the first shell layer.

14. In claim 13, forming a layer containing aggregate between the heat storage layer and the first shell layer and / or between the heat storage layer and the second shell layer.

15. In claim 11, forming the heat storage layer includes applying a heat insulating paint containing resin hollow beads as the hollow particles; The manufacturing method, wherein forming the first shell layer includes applying a paint containing a urethane resin or a polyurea resin.

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