JP7410609B1 - Heat storage material and heat storage film - Google Patents

Abstract

The present invention provides a novel heat storage material and heat storage film that can be easily formed into a film and can provide transparency. The present invention provides a heat storage material including a comb-shaped polymer having an amorphous main chain and a crystalline side chain, wherein the comb-shaped polymer has a glass transition temperature higher than the melting point of the crystalline side chain. Regarding heat storage materials. The present invention also relates to a heat storage film containing such a heat storage material. [Selection diagram] Figure 1

Description

The present invention relates to a heat storage material and a heat storage film.

In recent years, from the perspective of reducing carbon dioxide emissions, research and development have been actively conducted to effectively utilize thermal energy in building materials such as wall materials, floor materials, ceiling materials, and roof materials. A latent heat storage material is known as one of the materials for this purpose.

A latent heat storage material is a material that can store thermal energy by utilizing a phase change of the material, such as from solid to liquid. Unlike heat insulating materials, latent heat storage materials can use the stored heat and cold air as thermal energy when needed, so that heat can be used efficiently. In particular, a variety of materials are known, including block copolymers, organic substances such as paraffin, and inorganic substances such as sodium sulfate, because the phase change from solid to liquid is relatively easy to handle and the amount of heat that can be stored is high.

For example, Non-Patent Document 1 discloses that the thermal efficiency of a building is improved when double-glazed glass in which paraffin, which is a latent heat storage material, is filled between the glass windows is used.

In addition, Non-Patent Document 2 states that the comb-shaped polymer of polyalkylacrylamide has crystallinity in the alkyl side chain portion, and that the temperature at which the crystals of the alkyl side chain melt (melting point) is lower than the glass transition temperature of the comb-shaped polymer. It has been reported that it is low.

Changyu Liu, et al., “Effect of PCM thickness and melting temperature on thermal performance of double glazing units”, Journal of Building Engineering, 11(2017), 87-95 Kazuki Ebata, et al., “Nanophase Separation of Poly( N- alkyl acrylamides): The Dependence of the Formation of Lamellar Structures on Their Alkyl Side Chains”, Macromolecules, 2019, 52, 9773-9780

Conventional heat storage materials all utilize phase changes during the heat storage and heat radiation processes, so they are assumed to be in a liquid state either before or after the process. In addition, all conventional heat storage materials are cloudy because they are used in a powdered solid state. Furthermore, a heat storage material using paraffin needs to be encapsulated, so it is difficult to form it into a film. Heat storage materials using block copolymers utilize the latent heat that accompanies the melting of polymers, so even if they can be made into a film, there is a problem in that their mechanical properties change significantly during the heat storage and heat radiation processes.

An object of the present invention is to provide a novel heat storage material and heat storage film that can store and release heat while maintaining a solid state.

The present inventors have discovered that the above problem can be solved by the following aspects.
《Aspect 1》
A heat storage material comprising a comb-shaped polymer having an amorphous main chain and a crystalline side chain, wherein the glass transition temperature of the comb-shaped polymer is higher than the melting point of the crystalline side chain.
《Aspect 2》
The comb-shaped polymer has the amorphous main chain, the crystalline side chain, and a linking group that connects the amorphous main chain and the crystalline side chain, and the linking group has a polar The heat storage material according to aspect 1, comprising a group.
《Aspect 3》
The heat storage material according to aspect 2, wherein the connecting group includes one or more groups selected from the group consisting of an amide group, a urea group, a urethane group, a thioamide group, a thiourea group, and a thiourethane group.
《Aspect 4》
The heat storage material according to aspect 1, wherein the crystalline side chain contains a C ₄ to C ₃₀ hydrocarbon group.
《Aspect 5》
The heat storage material according to aspect 1, wherein the amorphous main chain is a hydrocarbon main chain having a degree of polymerization of 5 to 1000.
《Aspect 6》
The heat storage material according to aspect 1, wherein the comb-shaped polymer has a nanophase-separated structure having nanodomains formed by crystals of the crystalline side chains.
《Aspect 7》
The amorphous main chain is a hydrocarbon main chain with a degree of polymerization of 5 to 1000, the crystalline side chain contains a linear or branched C ₁₂ to C ₁₈ alkyl group, and the linking The heat storage material according to aspect 1, wherein the group includes one or more groups selected from the group consisting of an amide group, a urea group, and a urethane group.
《Aspect 8》
A heat storage film comprising the heat storage material according to any one of aspects 1 to 7.
《Aspect 9》
The heat storage film according to aspect 8, wherein the average absorbance of the absorption spectrum in the wavelength range of 400 to 800 nm is 0.5 or less when formed on a glass substrate to a thickness of 100 μm.
《Aspect 10》
A laminated heat storage film comprising the heat storage film according to aspect 8 and another polymer film.

According to the heat storage material and heat storage film of the present invention, it is possible to store and release heat while maintaining the solid state, so that the heat storage material and the heat storage film are very easy to handle. In one embodiment, this heat storage material and heat storage film can easily provide high heat storage performance and heat dissipation performance at a practical level. In one embodiment, this heat storage material and heat storage film can be easily formed into a film and easily impart transparency. The heat storage materials of the prior art do not become transparent both before and after the phase transition, but according to the heat storage material of one embodiment of the present invention, transparency is maintained before and after the crystal of the crystalline side chain melts. Therefore, it is very advantageous in applications where transparency is required, such as window glass and food packaging films.

FIG. 1 shows the appearance of the heat storage laminate film produced in the example. FIG. 2 shows the results of differential scanning calorimetry of polyoctadecyl acrylamide. FIG. 3 is a graph of the light absorption spectrum of the heat storage film, showing the transparency of the heat storage film. FIG. 4 is a graph of the light absorption spectrum of the heat storage laminate film, showing the transparency of the heat storage film. FIG. 5 shows the results of temperature increase and temperature decrease tests on the heat storage film. FIG. 6 shows the results of temperature rise and temperature fall tests on the heat storage laminate film.

In one embodiment, the heat storage material of the present invention includes a comb polymer having an amorphous main chain and a crystalline side chain, and the glass transition temperature of the comb polymer is higher than the melting point of the crystalline side chain.

In another embodiment, the method of use of the present invention is a method of using a comb-shaped polymer having an amorphous main chain and a crystalline side chain in a heat storage material, wherein the glass transition temperature of the comb-shaped polymer is higher than the melting point of the side chain.

Here, the "glass transition temperature" and "melting point" are determined from a DSC curve measured when a comb-shaped polymer is measured with a differential scanning calorimeter (DSC). For example, at the "glass transition temperature", a shift in the baseline of the endothermic amount occurs, and at the "melting point", a peak appears in the endothermic amount. Here, a part of the main chain of the comb-shaped polymer may be crystalline, and a part of the side chain may also be amorphous, but the "glass transition temperature" is due to the amorphous main chain. The "melting point" refers to the one resulting from crystalline side chains. In addition, amorphousness and crystallinity refer to the state at the temperature at which this heat storage material is used, and when used near room temperature, the amorphous main chain and crystalline side chain are respectively amorphous at room temperature. and crystallinity.

Generally, as a polymer having an amorphous portion and a crystalline portion increases from a low temperature to a high temperature, the glass transition temperature is reached first, and the amorphous portion begins to move. When the temperature is further increased, crystallization occurs, and then the melting point is reached and the crystalline portion of the crystalline portion melts. In contrast, the present inventors found that in the case of some comb-shaped polymers that have an amorphous main chain and a crystalline side chain, the crystalline part of the crystalline side chain first melts and the movement of that part begins. We found that the movement of the amorphous main chain begins after that. In this case, a glass transition temperature, usually below the melting point, is observed at a temperature above the melting point of the crystalline side chains.

The present inventors have discovered that such a comb-shaped polymer is extremely useful as a heat storage material. In other words, latent heat storage materials can normally store thermal energy by utilizing phase change between liquid and solid, but according to the comb-shaped polymer used in the present invention, it is possible to store thermal energy by utilizing a phase change between a liquid and a solid. As it is, the crystalline side chains can undergo crystal melting and crystallization, which can absorb and radiate heat, making it extremely easy to handle. Moreover, according to the comb-shaped polymer used in the present invention, it is possible to easily provide high heat storage and heat dissipation performance at a practical level. Furthermore, such comb-shaped polymers are easy to form into films and can easily provide transparency, so they can be used in applications that require transparency, such as window glass and food packaging films, which are difficult to imagine with conventional heat storage materials. It is very advantageous.

The glass transition temperature of the comb polymer may be, for example, 30°C or higher, 40°C or higher, 50°C or higher, or 60°C or higher, and 120°C or lower, 100°C or lower, 90°C or lower, or 80°C or lower. Good too. For example, the glass transition temperature of the comb-shaped polymer can be 30°C or more and 120°C or less, or 50°C or more and 100°C or less.

The melting point of the crystalline side chain of the comb-shaped polymer may be, for example, -30°C or higher, -20°C or higher, -10°C or higher, 0°C or higher, 10°C or higher, or 20°C or higher, and 50°C or lower, 40°C or higher. The temperature may be below 0°C, below 20°C, below 10°C, or below 0°C. For example, the melting point of the comb polymer can be -30°C or more and 50°C or less, or 0°C or more and 40°C or less.

The glass transition temperature of the comb polymer may be, for example, 30°C or higher, 40°C or higher, 50°C or higher, or 60°C or higher, and 80°C or lower, 70°C or lower, 60°C or lower, or 50°C or lower, It may be higher than the melting point of the crystalline side chain. For example, the glass transition temperature of the comb-shaped polymer may be greater than or equal to 30° C. and less than or equal to 80° C., and may be higher than the melting point of the crystalline side chain.

The number average molecular weight (Mn) of the comb-shaped polymer may be, for example, 5000 or more, 10000 or more, 15000 or more, 20000 or more, or 30000 or more, and 200000 or less, 100000 or less, 80000 or less, 60000 or less, or 50000 or less. It's okay. For example, the number average molecular weight (Mn) of the comb-shaped polymer can be 5,000 or more and 200,000 or less, or 20,000 or more and 100,000 or less. Here, the number average molecular weight (Mn) is determined in terms of standard polystyrene by gel permeation chromatography as described in Examples.

The molecular weight distribution (Mw/Mn) of the comb-shaped polymer may be, for example, 1.0 or more, 1.2 or more, 1.5 or more, 2.0 or more, or 2.5 or more, and 5.0 or less, 4 It may be .0 or less, or 3.0 or less. For example, the molecular weight distribution (Mw/Mn) of the comb-shaped polymer can be 1.0 or more and 5.0 or less, or 2.0 or more and 4.0 or less. The molecular weight distribution (Mw/Mn) is also determined in terms of standard polystyrene by gel permeation chromatography as described in Examples.

The average degree of polymerization of the comb-shaped polymer may be 6 or more, 8 or more, 10 or more, 20 or more, or 50 or more, and 1000 or less, 500 or less, 300 or less, 100 or less, 50 or less, 30 or less, or 20 or less. It may be. This average degree of polymerization may be, for example, 6 or more and 1000 or less, or 8 or more and 300 or less. The average degree of polymerization can be determined by calculating the molecular weight in terms of standard polystyrene by gel permeation chromatography as described in the Examples. By adjusting the molecular weight, degree of polymerization, etc. of the comb-shaped polymer, the operating temperature range, transparency, etc. of the heat storage material can be changed.

In one embodiment, the heat storage material has an amorphous main chain, a crystalline side chain, and a linking group that connects the amorphous main chain and the crystalline side chain, and the linking group has a polar Includes comb-shaped polymers containing groups. A comb-shaped polymer having such a linking group can reduce the degree of freedom of movement of the amorphous main chain due to intermolecular interaction between the linking group and surrounding chemical groups. The crystals of the crystalline side chains can be melted before the main chain begins to move. Therefore, such a heat storage material can store and release heat while maintaining its solid state.

The polar group is not limited as long as it can reduce the degree of freedom of movement of the amorphous main chain through intermolecular interaction with surrounding chemical groups, but examples include oxygen, nitrogen, sulfur, phosphorus, halogen, etc. can include. For example, the linking group includes a group formed by at least one of an ester group, a thioester, an ether group, a thioether, a carbonyl group, an amide group, an amine oxide group, an amino group, and a polyoxyalkylene group.

The linking group may in particular contain a secondary amino group, and in addition to the secondary amino group may contain an ether group, an ester group, a thioether group, and/or a thioester group. In this case, intermolecular interactions due to the linking group, such as hydrogen bonds, act strongly, and the degree of freedom of movement of the amorphous main chain tends to be reduced.

Specifically, examples of the linking group include an amide group (-CO-NH-), a urea group (-NH-CO-NH-), a urethane group (-NH-CO-O-), and a thioamide group (- CS-NH-), thiourea group (-NH-CS-NH-), and thiourethane group (-NH-CS-O-, -NH-CO-S-, or -NH-CS-S-) can include one or more groups selected from the group.

Although the main chain of the comb-shaped polymer is amorphous, a portion thereof may be crystalline as long as the advantageous effects of the present invention are achieved. The main chain of the comb-shaped polymer can form a structure called a nanophase-separated structure together with crystal nanodomains formed by crystalline side chains, and the entire comb-shaped polymer can be in an amorphous glass state.

The repeating unit of the amorphous main chain of the comb-shaped polymer is not particularly limited as long as the advantageous effects of the present invention can be obtained, and examples include hydrocarbon groups. In this specification, a hydrocarbon group may contain a hetero atom (for example, oxygen, nitrogen, sulfur, phosphorus, halogen, etc.), may be branched, or may contain a cyclic group. Good, refers to a hydrocarbon group. For example, the amorphous main chain of the comb polymer may be obtained by polymerizing unsaturated hydrocarbon groups.

The side chains of the comb-shaped polymer have crystallinity, but some of them may be amorphous as long as the advantageous effects of the present invention are achieved. The side chains of the comb-shaped polymer can constitute nano-sized aggregates and can become nanodomains with a nanophase-separated structure. The aggregates can, for example, have an average major axis of 100 nm or less, 50 nm or less, 30 nm or less, 20 nm or less, 10 nm or less, or 5 nm or less, thereby making the comb polymer transparent to visible light. can. The size of this aggregate can be determined by X-ray diffraction, as described in Non-Patent Document 2.

The crystalline side chain of the comb-shaped polymer is not particularly limited as long as the advantageous effects of the present invention can be obtained, and examples thereof include hydrocarbon groups. For example, as hydrocarbon groups, mention may especially be made of straight-chain or branched alkyl groups.

The number of carbon atoms in the crystalline side chain may be, for example, 4 or more, 6 or more, 8 or more, 10 or more, 12 or more, or 15 or more, or 50 or less, 40 or less, 30 or less, 25 or less, or 20 or less. , or 18 or less. The number of carbon atoms can be, for example, 4 to 50 or 10 to 30. By adjusting the number of carbon atoms in the crystalline side chain, the operating temperature range of the heat storage material can be changed.

The method for producing the comb-shaped polymer is not particularly limited, but for example, a first precursor compound containing a main chain and a part that becomes a part of a linking group is mixed with a second precursor compound containing a part of a linking group and a part that becomes a side chain. It can be obtained by reacting a precursor compound and then polymerizing a portion that will become the main chain. Alternatively, the second precursor compound can be grafted after the first precursor compound has been polymerized.

For example, when producing poly(meth)acrylamide having an alkyl side chain, a halogenated (meth)acryloyl such as acryloyl chloride is reacted with an alkylamine to obtain N-alkyl(meth)acrylamide, Thereafter, a comb-shaped polymer can be produced by radical polymerization in an organic solvent. For example, by adjusting the type and number of alkyl groups in the alkylamine, the side chains of the comb polymer can be changed.

The comb-shaped polymer produced in this way has one repeating unit with a structure in which one side chain is suspended from one monomer, but by copolymerizing such a monomer with another monomer, It may be a copolymer having multiple types of repeating units in a block or random pattern. The comb-shaped polymer preferably has repeating units having side chains in an amount of 50 mol% or more, 70 mol% or more, 80 mol% or more, 90 mol% or more, 95 mol% or more, or 100 mol%.

The comb-shaped polymer can have high heat storage performance and heat dissipation performance, and the amount of latent heat obtained can be, for example, 5 J/g or more, 10 J/g or more, 20 J/g or more, or 30 J/g or more, and 200 J/g or more. /g or less, 100 J/g or less, 80 J/g or less, 50 J/g or less, or 30 J/g or less. The amount of latent heat obtained by the comb-shaped polymer may be, for example, 5 J/g or more and 200 J/g or less, or 30 J/g or more and 50 J/g or less.

Depending on its application, the heat storage material can contain other substances besides the comb polymer, as long as the advantageous effects of the invention are not lost. For example, the heat storage material can be used by blending a comb-shaped polymer with another polymer, such as a polystyrene resin, a polyester resin, an acrylic resin, a polyamide resin, or a polyvinyl alcohol resin. , polyurethane resins, polyolefin resins, polycarbonate resins, polysulfone resins, derivatives thereof, and mixtures thereof. The heat storage material may contain fillers, lubricants, antistatic agents, mold release agents, plasticizers, antioxidants, antibacterial agents, fungicides, ultraviolet absorbers, etc. as necessary depending on its use. Additional additives may also be included.

The heat storage material may contain the comb-shaped polymer in an amount of 10% by mass or more, 10% by mass or more, 30% by mass or more, 50% by mass or more, 70% by mass or more, 90% by mass or more, or 95% by mass or more, and 100% by mass or more. It may be contained in an amount of not more than 95% by mass, not more than 90% by mass, not more than 80% by mass, not more than 60% by mass, or not more than 40% by mass. For example, the heat storage material can contain 10% by mass or more and 100% by mass or less of the comb-shaped polymer.

In one embodiment, the present invention relates to a thermal storage film comprising a thermal storage material as described above. When the heat storage material is used as a film, it is preferable because it can be used for various purposes, such as by pasting it on window glass or using it as part of a packaging film.

In another embodiment, the method of use of the present invention is the use of a comb-shaped polymer as described above in a thermal storage film.

In one embodiment, the thermal storage film can be transparent to visible light. Even if the heat storage material of the prior art was made into a film, it could not be made transparent during the entire process of heat storage and heat dissipation, whereas the heat storage film of the present invention is transparent during the entire process of heat storage and heat dissipation. I can do it. Here, transparent means that when a film is formed to a thickness of 100 μm on a glass substrate, the average absorbance of the absorption spectrum in the wavelength range of 400 to 800 nm is 0.5 or less, particularly 0.3 or less. , 0.1 or less, 0.05 or less, or 0.01 or less.

Such a heat storage film can be very suitably used in windows of buildings, front and rear windows of cars, food films covering fresh foods, vinyl greenhouses for plant production, and the like.

The thickness of the heat storage film is not particularly limited, and may be, for example, 10 μm or more, 50 μm or more, 100 μm or more, 500 μm or more, 1 mm or more, or 5 mm or more, and 100 mm or less, 10 mm or less, 1 mm or less, 500 μm or less, or 100 μm or less. , or 50 μm or less.

As a method for forming the heat storage film, known methods such as a solution casting method (solution casting method), a melt extrusion method, a calendar method, a compression molding method, etc. can be used. Among these, the solution casting method and the melt extrusion method can be mentioned. Examples of devices for performing the solution casting method include a drum-type casting machine, a band-type casting machine, a spin coater, and the like. Examples of the melt extrusion method include the T-die method and the inflation method. When a film is formed by melt extrusion, it may be stretched to form a stretched film.

The heat storage film can be laminated with other polymer films and used as a laminated heat storage film. By using other polymer films as the base film, it can be used for various applications.

Examples of other polymer films include polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polybutylene terephthalate, polyamide films such as 6-nylon and 6,6-nylon, polystyrene films, Examples include vinyl chloride film and synthetic paper.

When obtaining a laminated heat storage film, the heat storage film and another polymer film can be laminated by a known method such as coextrusion, thermocompression bonding, extrusion lamination, dry lamination, or the like.

The present invention will be explained in more detail with reference to the following examples, but the present invention is not limited thereto.

《Manufacturing example》
<Comb-shaped polymer>
N-octadecylamine (3.60 g) was dissolved in chloroform (60 mL) and stirred at 0°C. To this solution was added triethylamine (2.00 mL) followed by acryloyl chloride (1.17 mL) dropwise. After the addition of acryloyl chloride, the reaction mixture was stirred at 20° C. for 4 hours prior to the addition of methanol (5 mL). Then most of the solvent was evaporated under reduced pressure and THF (120 mL) was added. The resulting precipitate was filtered and the filtrate was evaporated under reduced pressure to precipitate a white solid of N-octadecyl acrylamide (ODA).

This white solid was dissolved in methanol (300 mL) and stored in the refrigerator for 1 day to promote recrystallization of ODA. The obtained crystals were identified by proton NMR measurement. Subsequently, free radical polymerization was performed by dissolving ODA in toluene, adding 1 mol % of 2,2'-azobisisobutyronitrile (AIBN) as an initiator, and reacting at 60° C. for 12 hours. The polymerization solvent was concentrated, and a comb-shaped polymer polyoctadecyl acrylamide (p(ODA)) was produced by reprecipitation using acetonitrile as a poor solvent.

The above reaction formula is shown below.

<Thermal storage film>
A film was formed on a glass substrate by a casting method using pODA as a comb-shaped polymer. The film thickness measured with a stylus stepmeter was 100 μm.

<Thermal storage laminated film>
A pODA film was produced by a casting method on a commercially available wrap (NEW Polywrap, Ube Film Co., Ltd.). For handling purposes, a commercially available plastic wrap was placed on the glass substrate, and a pODA film was produced thereon. When pODA was cast on the plastic wrap, the plastic wrap was wrinkled but remained transparent as shown in Figure 1. This is thought to be because pODA contracts when the solvent dries.

《Evaluation and results》
<Glass transition temperature and melting point>
The glass transition temperature and melting point of the comb-shaped polymer were measured using a differential scanning calorimeter (DSC; DSC 8231, Rigaku Corporation) at a nitrogen flow rate of 50 mL/min and a temperature increase rate of 10° C./min.

The results of DSC measurement of pODA are shown in FIG. 2.

The DSC spectrum of pODA in FIG. 2 has a large endothermic peak at 31.9°C, and also shows a baseline shift around 82.3°C. Since the former is a first-order phase transition, it is thought to originate from the melting of alkyl chains aggregated by nanophase separation of a polar main chain and a hydrophobic alkyl chain. The latter, on the other hand, is a second-order phase transition and is the glass transition temperature. Since the difference in these temperatures was 50° C. or more, it was found that the heat storage material of polyoctadecyl acrylamide exhibits a latent heat storage function without significantly changing its mechanical properties.

<Molecular weight>
The number average molecular weight (Mn) and molecular weight distribution (Mw/Mn) of pODA were measured by gel permeation chromatography (GPC; Shodex GPC-101, Resonac Co., Ltd.) using standard polystyrene. The columns used were columns (TSKgel Super HZ2000, TSKgel Super HZ3000, TSKgel Super HZ4000, TSKgel Super HZM-M, Tosoh Corporation) connected in this order.

As a result, the number average molecular weight of pODA was 40,000, and the molecular weight distribution (Mw/Mn) was 3.4.

<Light absorption spectrum>
Measure the absorbance of light in the wavelength range of 300 nm to 800 nm using ultraviolet-visible-near-infrared spectroscopy (UV3600i Plus, Shimadzu Corporation) for a sample of only a glass substrate and a sample of a glass substrate on which a heat storage film is formed. did.

Further, similar measurements were performed on both a sample in which only a commercially available plastic wrap was laminated on a glass substrate, and a sample in which a commercially available plastic wrap was laminated on a glass substrate and coated with pODA.

The results are shown in FIGS. 3 and 4.

As shown in Figure 3, the sample with only a glass substrate and the sample with a glass substrate on which a heat storage film is formed have substantially the same absorbance in the visible light range; I understand that there is something.

Furthermore, as shown in Figure 4, when comparing a sample in which only a plastic wrap was laminated on a glass substrate and a sample in which a plastic wrap was laminated on a glass substrate and coated with pODA, it was found that the sample coated with a pODA film was , no unique absorption peak was shown, and only an increase in the background due to scattering caused by the wrinkle formation of the wrap.

〈Temperature rise and fall test〉
Regarding the above heat storage film formed on a glass substrate, a fiber thermometer was attached to the glass substrate and left at 23°C for 20 seconds, and then placed on a hot plate at 48°C with the glass substrate side facing down to observe temperature changes. It was measured. Thereafter, the substrate was removed from the hot plate and left at room temperature. In the same way, measurements were also made on glass alone.

In addition, similar measurements were performed on both a sample in which only a wrap was laminated on a glass substrate and a sample in which a wrap was laminated on a glass substrate and coated with a pODA film.

The temperature changes are shown in FIGS. 5 and 6.

As shown in Figure 5, when measuring only the glass substrate, a temperature increase was observed immediately after placing it on the hot plate (at 20 seconds), whereas for the glass substrate coated with pODA, it was observed that the temperature increased within 2 seconds. A delayed rise in temperature was observed, and its slope was gradual. Furthermore, in the case of only the glass substrate, the maximum temperature was 43.2°C, whereas in the case of the glass substrate coated with pODA, it was 42.2°C, which was 1°C lower.

Furthermore, when the glass substrate was removed from the hot plate (at 80 seconds) and left at room temperature, the temperature of the glass substrate alone decreased rapidly, whereas the temperature of the glass substrate coated with pODA decreased slowly. There is. This is because when placed on a hot plate, the alkyl side chains melted and absorbed heat, suppressing the rise in temperature. However, when taken out from the hot plate, the molten alkyl chains melted and absorbed heat. This can be said to be due to heat generation caused by crystallization. Note that there was no change in the transparency of pODA during this temperature change. This revealed that the pODA film exhibits a latent heat storage function while maintaining transparency.

As shown in FIG. 6, as in the case of FIG. 5, the sample in which the wrap on the glass substrate was coated with the pODA film had a longer delay time in temperature rise, and the temperature rise was also gradual. Furthermore, the temperature reached was 0.5°C lower than in the case of wrapping only.

Note that even in the sample where the wrap was coated with pODA film, its transparency was maintained. Thus, it was found that pODA can be easily applied not only to hard glass substrates but also to soft wraps, and maintains its transparency and latent heat storage function. This can be said to be because the glass state of the film is maintained because the melting and crystallization of the crystalline side chains, which are the origin of latent heat storage, occur below the glass transition temperature.

In addition, when the number of carbon atoms in the octadecyl group (alkyl group) of octadecylamine was changed to 12 to 17, and comb-shaped polymers with various side chain lengths were obtained and similar experiments were conducted, Although the appropriate temperature range etc. were changed, generally the same results were obtained.

Claims (8)

A heat storage material comprising a comb-shaped polymer having an amorphous main chain and a crystalline side chain, the glass transition temperature of the comb-shaped polymer being higher than the melting point of the crystalline side chain,
The comb-shaped polymer has the amorphous main chain, the crystalline side chain, and a linking group that connects the amorphous main chain and the crystalline side chain, and
A heat storage material, wherein the linking group includes one or more groups selected from the group consisting of an amide group, a urea group, a urethane group, a thioamide group, a thiourea group, and a thiourethane group . The heat storage material according to claim 1, wherein the crystalline side chain contains a C ₄ to C ₃₀ hydrocarbon group. The heat storage material according to claim 1, wherein the amorphous main chain is a hydrocarbon main chain having a degree of polymerization of 5 to 1000. The heat storage material according to claim 1, wherein the comb-shaped polymer has a nanophase-separated structure having nanodomains formed by crystals of the crystalline side chains. The amorphous main chain is a hydrocarbon main chain with a degree of polymerization of 5 to 1000, the crystalline side chain contains a linear or branched C ₁₂ to C ₁₈ alkyl group, and the linking The heat storage material according to claim 1, wherein the group includes one or more groups selected from the group consisting of an amide group, a urea group, and a urethane group. A heat storage film comprising the heat storage material according to any one of claims 1 to 5 . The heat storage film according to claim 6 , wherein the average absorbance of the absorption spectrum in the wavelength range of 400 to 800 nm is 0.5 or less when formed on a glass substrate to a thickness of 100 μm. A laminated heat storage film comprising the heat storage film according to claim 6 and another polymer film.

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