JP6626643B2 - Thermally responsive thickness variable material, thermal control device using the thermally responsive thickness variable material, and thermal control method using the thermally responsive thickness variable material - Google Patents

Description

  The present invention relates to a thermally responsive thickness variable material, a thermal control device using the thermally responsive thickness variable material, and a thermal control method using the thermally responsive thickness variable material.

  Insulating materials are used in many fields.For example, rechargeable batteries have an appropriate temperature range to fully demonstrate their performance. Insulation is used to prevent lowering.

  However, if the rechargeable battery is covered with a heat insulating material or the like, the heat generated when the rechargeable battery is used cannot be released, so that the temperature of the rechargeable battery increases and its performance decreases.

  Conventionally, in order to solve this problem, there has been known a thermal control device in which a rechargeable battery is covered with a heat insulating material and cooled by a fan or the like when the temperature of the rechargeable battery reaches a certain temperature or higher (Patent Document 1).

  However, in the conventional heat control device, it is necessary to provide a cooling device separately from the heat insulating material, and the heat control device becomes large. Further, when a cooling fan or the like is provided as a cooling device, there is a problem that electric power for continuously turning the fan during cooling is required, and a very complicated wiring configuration and the like are required. Further, when a heat pipe or the like is provided as a cooling device (Patent Document 2), when a means for changing the thickness of a heat insulating material is provided (Patent Document 3), and when a means for applying an electric field or the like is provided (Patent Document 4). Similarly, the structure becomes very complicated and large.

JP 2001-76771 A JP-A-10-55827 JP 2013-113408 A JP 2013-234244 A

  The present invention has been made in view of the above problems, and provides a heat control device and a material for realizing a heat control method with a simple and compact configuration that does not require a cooling device or the like separately from a heat insulating material. The purpose is to:

  The present invention relates to a thermoresponsive variable thickness material in which a filler is dispersed in a thermoresponsive material whose thickness decreases when the temperature is equal to or higher than a predetermined temperature.

  The filler is preferably a heat conductive filler.

  It is preferable that the thermally conductive filler has a higher thermal conductivity than the thermally responsive material. By reducing the thickness of the thermally responsive thickness variable material at a temperature equal to or higher than a predetermined temperature, the thermally conductive fillers are close to each other, and the thermal conductivity of the thermally responsive thickness variable material is further increased. Can be.

  The thermal responsive thickness variable material of the present invention has a high thermal conductivity due to a decrease in thickness when the temperature is higher than a predetermined temperature. Furthermore, since the thermally responsive thickness variable material of the present invention has a thermally conductive filler dispersed therein, the thickness of the thermally responsive thickness variable material is reduced at a temperature equal to or higher than a predetermined temperature. The fillers come into contact with each other to secure a heat transfer path, thereby increasing the thermal conductivity. When the temperature is less than a predetermined temperature, the thickness of the thermally responsive variable thickness material of the present invention returns to the original state, and the thermally conductive fillers are separated from each other, the heat transfer path is cut off, and the thermal conductivity is reduced. In the state of. That is, the thermally responsive thickness variable material of the present invention can change the thermal conductivity depending on the temperature, so that the heat insulating function and the heat radiating function can be switched. Therefore, according to the present invention, it is possible to provide a material for realizing a heat control device and a heat control method with a simple and compact structure that does not require a cooling device or the like separately from the heat insulating material.

FIG. 1 is a schematic diagram illustrating a heat control device according to an embodiment of the present invention. Schematic diagram showing the heat control device when the temperature is equal to or higher than a predetermined temperature

<Heat-responsive variable thickness material>
The thermally responsive thickness variable material of the present invention is a material in which a filler is dispersed in a thermally responsive material whose thickness becomes smaller at a temperature equal to or higher than a predetermined temperature.

(Thermal responsive material)
The thermo-responsive material is not particularly limited as long as the material changes its shape at a temperature higher than a predetermined temperature to decrease its thickness, and at a temperature lower than the predetermined temperature, the material returns to its original shape and its thickness returns to its original thickness. Not done. Examples of the material include liquid crystal elastomers. Examples of the liquid crystal elastomer include liquid crystal polyurethane elastomer, liquid crystal silicone elastomer, liquid crystal acrylate elastomer, poly N-substituted (meth) acrylamide (for example, poly N-isopropylacrylamide), and polyvinyl ether. Although one of them can be exemplified, which one to use is appropriately determined in consideration of the characteristics of the object for controlling heat (hereinafter, the object is also referred to as a heat control object), environmental temperature, desired heat insulation performance, heat radiation performance, and the like. be able to.

  As an example, when the thermal control object is assumed to be used near normal temperature (for example, −10 to 40 ° C.) (for example, the rechargeable batteries described in Patent Documents 1 and 2), the thermal response As a material used for the variable thickness material, a liquid crystal elastomer is preferable from the viewpoint of weight reduction and a viewpoint of switching between heat insulation performance and heat radiation performance, and among the liquid crystal elastomers, a liquid crystal polyurethane elastomer is preferable.

[Liquid crystal elastomer]
As an example of the liquid crystal elastomer, a liquid crystal compound obtained by adding an alkylene oxide and / or styrene oxide to a mesogen group-containing compound having an active hydrogen group is reacted with a compound that reacts with the active hydrogen group of the liquid crystal compound. And the resulting liquid crystal elastomer. The liquid crystal compound has a low temperature range in which liquid crystallinity is exhibited. By using the liquid crystal compound, reaction curing can be performed without a solvent and in a state where liquid crystallinity is developed. Since the liquid crystal elastomer has a low temperature range in which the liquid crystal compound of the raw material exhibits liquid crystallinity and has a network structure by crosslinking, it has liquid crystallinity and rubber elasticity at low temperature (around room temperature). In the liquid crystal elastomer, since the mesogenic groups are uniaxially oriented, the degree of orientation of the mesogenic groups decreases by application of heat and shrinks in the direction of orientation, and the degree of orientation of the mesogenic groups increases by removing heat. It shows a characteristic response behavior of extending in the orientation direction.

[Liquid crystal compound obtained by adding alkylene oxide and / or styrene oxide to a mesogen group-containing compound having an active hydrogen group]
The mesogen group-containing compound is represented by the following general formula (1) from the viewpoint of exhibiting liquid crystallinity and rubber elasticity at a low temperature (for example, a temperature at which the use of the rechargeable batteries described in Patent Documents 1 and 2 is assumed). Preferably, the compound is

（式中、Ｘは活性水素基であり、Ｒ_１は単結合、−Ｎ＝Ｎ−、−ＣＯ−、−ＣＯ−Ｏ−、又は−ＣＨ＝Ｎ−であり、Ｒ_２は単結合、又は−Ｏ−であり、Ｒ_３は単結合、又は炭素数１〜２０のアルキレン基である。ただし、Ｒ_２が−Ｏ−であり、かつＲ_３が単結合である場合を除く。）

Wherein X is an active hydrogen group, R ₁ is a single bond, -N = N-, -CO-, -CO-O-, or -CH = N-, and R ₂ is a single bond, or —O—, and R ₃ is a single bond or an alkylene group having 1 to 20 carbon atoms, provided that R ₂ is —O— and R ₃ is a single bond.

X includes, for example, OH, SH, NH ₂ , COOH, or a secondary amine.

In order to obtain a thermoresponsive material having a transition temperature (Ti) from a liquid crystal phase to an isotropic phase or from an isotropic phase to a liquid crystal phase of 0 to 100 ° C., a biphenyl skeleton (R ₁ is a single bond) is provided. Preferably, a compound is used. When R ₃ is an alkylene group, it preferably has 2 to 10 carbon atoms.

  The alkylene oxide to be added is not particularly limited, and examples thereof include ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide, cyclohexene oxide, epichlorohydrin, epibromohydrin, methyl glycidyl ether, and allyl. Glycidyl ether and the like. The styrene oxide to be added may have a substituent such as an alkyl group, an alkoxyl group, or a halogen on the benzene ring. In order to obtain a thermoresponsive material having a transition temperature (Ti) from a liquid crystal phase to an isotropic phase or from an isotropic phase to a liquid crystal phase of 0 to 100 ° C., ethylene oxide, propylene oxide, 1,2-butylene oxide It is preferable to add at least one oxide selected from the group consisting of, 2,3-butylene oxide and styrene oxide.

  Further, the alkylene oxide and / or styrene oxide is preferably added in an amount of 2 to 10 mol, more preferably 2 to 8 mol, per 1 mol of the compound represented by the general formula (1). When the number of moles added is less than 2 mol, it is difficult to sufficiently lower the temperature range in which the liquid crystallinity of the liquid crystal compound is developed, and it is difficult to perform reaction curing in a state where the liquid crystallinity is developed without a solvent. Tends to be. On the other hand, when the number of added moles exceeds 10 mol, the liquid crystal compound tends not to exhibit liquid crystallinity.

  The liquid crystal compound preferably has a transition temperature (Ti) from a liquid crystal phase to an isotropic phase or from an isotropic phase to a liquid crystal phase of 15 to 150 ° C, and more preferably 25 to 125 ° C.

  The liquid crystal compounds may be used alone or in combination of two or more.

(Compound that reacts with the active hydrogen group of the liquid crystal compound)
Examples of the compound that reacts with the active hydrogen group of the liquid crystal compound include an isocyanate compound, an epoxy compound, a silanol group-containing compound, a halide, a carboxylic acid, and an alcohol. In particular, it is preferable to use an isocyanate compound in order to obtain a thermoresponsive material having a transition temperature (Ti) from a liquid crystal phase to an isotropic phase or from an isotropic phase to a liquid crystal phase of 0 to 100 ° C. Hereinafter, the liquid crystal elastomer will be described using a liquid crystal polyurethane elastomer as an example.

  As the isocyanate compound which is a raw material of the liquid crystal polyurethane elastomer, a compound known in the field of polyurethane can be used without particular limitation. For example, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthalenediisocyanate, p-phenylene Aromatic diisocyanates such as diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, aliphatic diisocyanates such as ethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and 1,6-hexamethylene diisocyanate 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, Cycloaliphatic diisocyanates such as Rubo Renan diisocyanate. These may be used alone or in combination of two or more.

  In order to introduce a crosslinking point into the liquid crystal polyurethane elastomer to form a network, it is preferable to use a trifunctional or more isocyanate compound in combination, and particularly preferable to use a trifunctional isocyanate compound in combination. Examples of the trifunctional or higher isocyanate compound include triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, and 1,6,11-undecane triisocyanate. , 1,8-diisocyanate-4-isocyanatomethyloctane, and triisocyanates such as bicycloheptane triisocyanate, and tetraisocyanates such as tetraisocyanate silane. These may be used alone or in combination of two or more. Further, multimerized diisocyanate may be used. The multimerized diisocyanate is an isocyanate-modified product or a mixture thereof which is multiplied by addition of three or more diisocyanates. Examples of the modified isocyanate include 1) a trimethylolpropane adduct type, 2) a buret type, and 3) an isocyanurate type.

  When a diisocyanate and a trifunctional isocyanate compound are used in combination, it is preferable to mix the former / the latter at a weight ratio of 19/1 to 1/1.

  A high molecular weight polyol may be used as long as the effect of the liquid crystal elastomer is not impaired. As the high molecular weight polyol, a high molecular weight polyol having 3 or more hydroxyl groups may be used in order to form a network by introducing a crosslinking point into the liquid crystal polyurethane elastomer. The number of hydroxyl groups is preferably 3. High molecular weight polyols include polyether polyols, polyester polyols, polycarbonate polyols, polyester polycarbonate polyols, and the like. These may be used alone or in combination of two or more.

  In addition to the high molecular weight polyol, a low molecular weight compound containing an active hydrogen group may be used as long as the effect of the liquid crystal elastomer is not impaired. The active hydrogen group-containing low molecular weight compound is a compound having a molecular weight of less than 400, for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butane Diol, 1,4-butanediol, 2,3-butanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, diethylene glycol, triethylene Glycol, 1,4-bis (2-hydroxyethoxy) benzene, trimethylolpropane, glycerin, 1,2,6-hexanetriol, pentaerythritol, tetramethylolcyclohexane, methylglucoside, sorbitol, mannitol, dulcitol, sucrose, Low molecular weight polyols such as 2,6,6-tetrakis (hydroxymethyl) cyclohexanol, diethanolamine, N-methyldiethanolamine and triethanolamine; low molecular weight polyamines such as ethylenediamine, tolylenediamine, diphenylmethanediamine and diethylenetriamine; monoethanol Examples include amines, alcohol amines such as 2- (2-aminoethylamino) ethanol, and monopropanolamine. These active hydrogen group-containing low molecular weight compounds may be used alone or in combination of two or more.

  The liquid crystal elastomer preferably contains 50 to 90% by weight of the liquid crystal compound as a raw material, and more preferably 60 to 80% by weight. By increasing the content of the mesogenic group by increasing the blending amount of the liquid crystal compound, a liquid crystal elastomer that is greatly deformed by a change in temperature can be obtained. In the present invention, since the liquid crystal compound is used, the liquid crystal elastomer obtained even if the content of the liquid crystal compound is increased has a low elastic modulus. When the content of the liquid crystal compound is less than 50% by weight, the liquid crystal of the liquid crystal elastomer tends to be hardly developed. On the other hand, when the content of the liquid crystal compound exceeds 90% by weight, it is difficult to introduce a crosslinking point into the molecule, so that curing tends to be difficult.

  The liquid crystal polyurethane elastomer is obtained by heating a polyurethane raw material composition and curing it by a urethanization reaction. Then, during the urethanization reaction, the mesogen groups of the liquid crystal compound are uniaxially oriented in a state where the liquid crystal compound has exhibited liquid crystallinity, and the liquid crystal compound is cured with the mesogen groups oriented. The method for orienting the mesogen group in the uniaxial direction is not particularly limited. And the like.

  By adding an alkylene oxide and / or styrene oxide to a mesogen group-containing compound having an active hydrogen group, the thermal stability of the mesogen group is reduced, and the temperature range in which liquid crystallinity is exhibited can be reduced. By using the liquid crystal compound, reaction curing can be performed without a solvent and in a state where liquid crystallinity is developed. By performing the reaction curing in a state where the liquid crystallinity is developed, the crystallinity of the mesogen can be inhibited and the formation of a crystal phase can be prevented.

  The content of the liquid crystal compound in the polyurethane raw material composition is preferably from 50 to 90% by weight, and more preferably from 60 to 80% by weight. The polyurethane raw material composition is prepared by mixing each raw material component under solvent-free conditions.

  The liquid crystal polyurethane elastomer may be manufactured by a prepolymer method or may be manufactured by a one-shot method. Note that a known catalyst such as a tertiary amine-based catalyst that promotes a urethane reaction may be used.

  The liquid crystal elastomer preferably has a transition temperature (Ti) from a liquid crystal phase to an isotropic phase or from an isotropic phase to a liquid crystal phase of 0 to 100 ° C, and more preferably 0 to 85 ° C.

  The adjustment of the predetermined temperature can be performed by adjusting the Ti of the liquid crystal polyurethane elastomer. Ti of the liquid crystal polyurethane elastomer can be adjusted by various methods. For example, when the number of addition of the alkylene oxide of the mesogen diol represented by the general formula (1) is large, the Ti becomes small, and when the number of addition is small, the Ti becomes large. Therefore, the number of addition of the alkylene oxide is adjusted. By doing so, Ti can be adjusted. As another example, when the number of cross-linking points in the liquid crystal polyurethane elastomer is large, Ti becomes small, and when the number of cross-linking points is small, Ti becomes large. Therefore, Ti can be adjusted by adjusting the cross-linking agent. As another example, when the composition is adjusted in a direction that inhibits the aggregation of mesogen, which is a source of liquid crystallinity, Ti becomes small, and when the composition is adjusted in a direction that induces aggregation, Ti becomes large. Can be adjusted to adjust the Ti. In addition, since Ti increases as the content of the mesogendiol increases, Ti of the liquid crystal polyurethane elastomer can be adjusted by adjusting the content. If a highly crystalline isocyanate compound or an aromatic ring-containing isocyanate compound is used as the isocyanate compound as a raw material of the liquid crystal polyurethane elastomer, Ti tends to increase, so that Ti can be adjusted depending on the type of the isocyanate compound.

  In the liquid crystal polyurethane elastomer, since the stretching direction of monodomain formation (orientation direction of monodomain) is the deformation direction, the direction of shape change can be adjusted based on the orientation direction (stretching direction). Adjustment of the amount of change in the shape of the liquid crystal polyurethane elastomer is, for example, the liquid crystal polyurethane elastomer has a larger stretching amount, that is, the larger the degree of orientation, the larger the deformation amount. The amount of deformation can be adjusted. As another example, the amount of deformation is reduced when there are many crosslinking points in the liquid crystal polyurethane elastomer, and the amount of deformation is increased when the number of crosslinking points is small, so that the amount of deformation is adjusted by adjusting the crosslinking agent. Can be adjusted. As another example, the amount of deformation is reduced when the composition is adjusted in a direction that inhibits the aggregation of mesogen, which is a source of liquid crystallinity, and the amount of deformation is increased when the composition is adjusted in a direction that induces aggregation. The amount of deformation can be adjusted by adjusting the aggregation of the mesogen.

  The liquid crystal elastomer used for the thermoresponsive thickness variable material may have a void inside to improve heat insulation. When having a gap, when the temperature is lower than a predetermined temperature, the thermal conductivity is low and the heat insulating property is excellent, and when the temperature is equal to or higher than the predetermined temperature, the degree of shape change is larger than that of a thermoresponsive thickness variable material having no gap. And the thermal conductivity increases. That is, it is preferable because the heat insulation performance and the heat radiation performance can be largely switched. The porosity has a desired heat insulating performance, and it is sufficient if the thermal conductivity of the thermally responsive thickness variable material can be changed by a shape change with temperature. The voids may be independent or continuous, but it is preferable that the continuous porosity is high from the viewpoint of easy change of the shape of the thermoresponsive thickness variable material. The porosity and the continuous porosity can be appropriately set depending on desired heat insulation performance and heat radiation performance.

(Filler)
By dispersing the filler in the thermoresponsive material, the breaking strength of the thermoresponsive thickness variable material can be improved. The filler to be dispersed only needs to have a reinforcing function, and a known filler can be used without any particular limitation. The filler is preferably a thermally conductive filler, particularly preferably a filler having a higher thermal conductivity than the thermally responsive material. As the heat conductive filler, for example, boron nitride, aluminum nitride, boron nitride, alumina, carbon particles, carbon fiber, magnesium oxide, silica, zinc oxide, pure iron, carbonyl iron powder, Mn-Zn ferrite, Ni-Zn Ferrite, magnetite, cobalt, nickel and the like. Among them, boron nitride having a certain aspect ratio has the characteristic that its thermal conductivity differs greatly in the vertical and horizontal directions. This is preferable because the rate of change of the rate becomes larger.

  The volume occupancy of the thermally responsive thickness variable material in the thermally responsive thickness variable material facilitates the improvement of the thermal conductivity by the heat transfer path due to the mutual contact of the thermally responsive filler accompanying the shape change of the thermally responsive thickness variable material. From the viewpoint, 5 vol% or more is preferable, and 10 vol% or more is more preferable. In addition, the volume occupancy of the thermally responsive thickness variable material in the thermally responsive thickness variable material is determined by preventing the thermally responsive filler from contacting each other when the thermally responsive thickness variable material does not change shape. From the viewpoint of increasing the change in conductivity, 40 vol% or less is preferable, and 30 vol% or less is more preferable.

  The average particle size of the heat conductive filler is not particularly limited, but is preferably 0.1 μm or more, and more preferably 1 μm or more from the viewpoint of adding a required volume. The average particle diameter of the thermally conductive filler is dispersed in the thermally responsive material to prevent the thermally conductive filler from contacting each other when there is no change in the shape of the thermally responsive thickness variable material. 500 μm or less is preferable, and 300 μm or less is more preferable, from the viewpoint of increasing the change in thermal conductivity accompanying the change. The heat conductive filler may be used alone or in combination of two or more kinds having different average particle diameters. In the present specification, the average particle diameter is measured by the method described in Examples.

  The aspect ratio of the thermally conductive filler, from the viewpoint of making it easier for heat transfer paths to be formed when the shape of the thermally responsive thickness variable material changes, and increasing the change in thermal conductivity due to the shape change of the thermally responsive thickness variable material. One or more is preferable, and three or more is more preferable. In addition, the aspect ratio of the thermally conductive filler is dispersed in the thermally responsive material to prevent the thermally conductive filler from contacting each other when the thermally responsive thickness variable material does not change shape, and to change the shape. Is preferably 250 or less, and more preferably 200 or less, from the viewpoint of increasing the change in the thermal conductivity due to the above. The “aspect ratio” of the thermally conductive filler refers to the ratio of the average major axis to the average minor axis (average major axis / average minor axis) of the thermal conductive filler. The average minor axis refers to the length of the shorter side of the thermally conductive filler, and the average major axis refers to the length of the longer side of the thermally conductive filler. In this specification, the aspect ratio is measured by the method described in Examples.

<Heat control device>
The thermal control device according to the present embodiment has the thermoresponsive thickness variable material. A heat control device using the thermoresponsive thickness variable material will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a thermal control device 1 using the thermally responsive thickness variable material.

  The thermal control device 1 has at least the thermally responsive thickness variable material 2. The thermally responsive thickness variable material 2 has a thermally conductive filler 3.

  The thermally responsive thickness variable material 2 is provided so as to cover the periphery of the thermal control target 4. In FIG. 1, the thermally responsive thickness variable material 2 is provided so as to surround four sides of the thermal control target 4, but is not limited thereto, and may be appropriately determined depending on the use environment of the thermal control target 4. It is possible to change.

  FIG. 2 is a schematic diagram illustrating an example of a state in which the temperature is increased and becomes equal to or higher than a predetermined temperature, whereby the thermally responsive thickness variable material 2 is deformed and the thickness is reduced. The thermally responsive variable thickness material 2 has a high heat insulating effect because the thermal conductivity is low when the thermally conductive filler is far away from the thermally conductive filler as shown in FIG. On the other hand, as shown in FIG. 2, the thickness of the thermally responsive thickness variable material 2 is reduced by heat, and the thermal conductivity is high in a state where a heat transfer path is secured by contact of the thermally conductive fillers with each other. Therefore, the heat insulation effect can be reduced. Further, when the temperature decreases and becomes lower than the predetermined temperature, the thermoresponsive thickness variable material 2 returns to the original state as shown in FIG. The thermal control device 1 according to the present embodiment can adjust the thermal conductivity and switch between the heat insulating property and the heat radiating property with the above configuration, and thus can control the heat of the thermal control target 4. .

  Hereinafter, the thermoresponsive thickness variable material of the present invention will be described in detail based on examples, but the present invention is not limited to these examples.

<Evaluation method>
[Measurement and evaluation methods]
(Calculation of the content of the liquid crystal compound)
The content of the liquid crystal compound in the polyurethane elastomer was calculated by the following equation.
Content of liquid crystal compound (% by weight) = {(weight of liquid crystal compound) / (weight of all raw material components of polyurethane elastomer other than filler)} × 100

[Measurement of transition temperature (Ti) of liquid crystal compound and polyurethane elastomer from liquid crystal phase to isotropic phase]
Ti was measured at 20 ° C./min using a differential scanning calorimeter DSC (trade name: X-DSC 7000, manufactured by Hitachi High-Tech Science Corporation).

(Evaluation of liquid crystal properties)
The presence or absence of liquid crystallinity of the liquid crystal compound and the polyurethane elastomer is determined by a polarizing microscope (manufactured by Nikon Corporation, trade name: LV-100POL) and a differential scanning calorimeter DSC (manufactured by Hitachi High-Tech Science Corporation, trade name: X-DSC 7000) ) Was evaluated under the condition of 20 ° C./min.

(Average particle size)
It was measured by Shimadzu laser diffraction particle size distribution analyzer SALD2200. In the present specification, the average particle diameter is a 50% particle diameter (median diameter D ₅₀ ) when the particle size distribution measured by a laser diffraction type particle size distribution analyzer is integrated from the fine particle side on a volume basis in an aqueous dispersion. Say.

〔aspect ratio〕
The average minor axis and average major axis of the thermally conductive filler are measured by directly observing with a transmission electron microscope (TEM). The fifty thermally conductive fillers are sampled indiscriminately, the average minor axis and the average major axis are individually counted, the average value is defined as the average minor axis and the average major axis, and the ratio of the average major axis to the average minor axis (average major axis) (Average minor axis) was taken as the aspect ratio.

(Performance evaluation of thermoresponsive thickness variable material)
The evaluation of the thermoresponsive thickness variable material was performed using a device in which a heat flow meter (M55A, 2300A, manufactured by Eto Electric Co., Ltd.) and a rubber heater (Samicon 230, SBX3030K1S) were combined.
1) Thermal conductivity The thermal conductivity of the thermally responsive thickness variable material was measured by a heat flow meter in the thickness direction of the thermally responsive thickness variable material according to JISA 1412-2.
2) Thickness change rate The thickness change rate is defined as 100% when the thickness of the thermally responsive thickness variable material (100 mm long × 100 mm wide × 10 mm thick) at a temperature lower than a predetermined temperature is equal to or higher than a predetermined temperature. It shows the degree of change in the thickness of the thermoresponsive thickness variable material at that time. The thickness change rate was determined by the following equation.
Thickness change rate (%) = (thickness of thermally responsive thickness variable material at or above a predetermined temperature / thickness of thermally responsive thickness variable material at or below a predetermined temperature) × 100
3) Thermal conductivity change rate The thermal conductivity change rate is defined as the thermal responsiveness when the thermal conductivity of the thermally responsive thickness variable material is lower than a predetermined temperature is 100% and the thermal responsiveness is higher than a predetermined temperature. It indicates the degree of change in the thermal conductivity of the thickness variable material. The larger the value, the more the thermal conductivity has changed. The rate of change in thermal conductivity was determined by the following equation.
Thermal conductivity change rate (%) = (thermal conductivity of thermally responsive thickness variable material at or above a predetermined temperature / thermal conductivity of thermally responsive thickness variable material at or below a predetermined temperature) × 100

<Examples and comparative examples>
[Example 1]
[Synthesis of Mesogendiol as Liquid Crystalline Compound]
BH6 (100 g), KOH 3.8 g, and DMF 600 ml were put and mixed in a reaction vessel, and then 4 equivalents of propylene oxide were added to BH6 (1 mol), and reacted at 120 ° C. for 2 hours under pressure. Was. Thereafter, 3.0 g of oxalic acid was added to stop the addition reaction, the salt was removed by suction filtration, and DMF was further removed by distillation under reduced pressure to obtain the target mesogendiol (even if it contained structural isomers). Good). The reaction is shown in the following chemical formula 2.

（式中、ｎ＝２である。）

(Where n = 2)

[Synthesis of polyurethane elastomer and preparation of thermoresponsive thickness variable material]
20 g of the mesogendiol, 6.9 g of hexamethylene diisocyanate, 0.8 g of HDI-based isocyanurate (Sumijur N3300, manufactured by Sumika Bayer Urethane Co., Ltd.), and carbonyl iron powder CI-CS (manufactured by BASF, average particle diameter 6 μm (D ₅₀ ), aspect ratio 1) 20 g were mixed at 100 ° C. Thereafter, the reaction solution was poured into a mold heated to 100 ° C. in advance and cured at 100 ° C. for 30 minutes to obtain a semi-cured liquid crystal polyurethane elastomer of a predetermined size. After releasing from the mold, the sample was stretched in a uniaxial direction at 20 ° C. to produce a thermoresponsive thickness variable material.

[Example 2 and Comparative Example]
A polyurethane elastomer was obtained in the same manner as in Example 1 except that the raw materials and the composition shown in Table 1 were employed. The boron nitride used was dencaboron nitride-GP (average particle diameter 8.0 (D ₅₀ ), aspect ratio 8.7, manufactured by Denki Kagaku Kogyo KK).

  Table 2 shows the evaluation results.

  Although the present invention has been described in detail, the above description is merely an example of the present invention in every aspect, and is not intended to limit the scope thereof. Various modifications and variations can be made without departing from the scope of the invention.

  The thermally responsive thickness variable material according to the present invention can be used for a heat control device and a heat control method. For example, it is suitable for a heat control device and a heat control method for adjusting the temperature of a rechargeable battery mounted on an automobile. Can be used.

DESCRIPTION OF SYMBOLS 1 Thermal control device 2 Thermoresponsive thickness variable material 3 Thermal conductive filler 4 Thermal control object

Claims (6)

In a thermoresponsive material whose thickness is reduced when the temperature is equal to or higher than a predetermined temperature, a filler is dispersed, a thermoresponsive thickness variable material,
Said heat responsive material is a reaction product of a liquid crystalline compound by adding an alkylene oxide and / or styrene oxide to the mesogenic group-containing compound having an active hydrogen group, with an isocyanate compound that reacts with an active hydrogen group in the liquid crystalline compound Oh Ru is a liquid crystal polyurethane elastomer,
A thermoresponsive thickness variable material in which the liquid crystal polyurethane elastomer has an orientation, and the thickness is reduced by changing the property of the orientation at or above a predetermined temperature.   The thermally responsive thickness variable material according to claim 1, wherein the filler is a thermally conductive filler. The thermally conductive filler has a higher thermal conductivity than the thermally responsive material,
The thermally responsive thickness variable according to claim 2, wherein the thickness of the thermally responsive material is reduced when the temperature is equal to or higher than a predetermined temperature, whereby the thermally conductive fillers are close to each other and have a high thermal conductivity. material.   The thermally responsive thickness variable material according to claim 2 or 3, wherein a volume occupancy of the thermally conductive filler is 5 to 40 vol%.   A thermal control device using the thermally responsive thickness variable material according to claim 1. A method for producing a thermoresponsive thickness-variable material, in which a filler is dispersed in a liquid crystal polyurethane elastomer whose thickness is reduced due to a change in alignment properties when the temperature is equal to or higher than a predetermined temperature,
A polyurethane raw material composition comprising a liquid crystal compound obtained by adding an alkylene oxide and / or styrene oxide to a mesogen group-containing compound having an active hydrogen group, an isocyanate compound that reacts with the active hydrogen group of the liquid crystal compound, and the filler Heating to perform a urethanization reaction, during the urethanization reaction, a step of uniaxially orienting the mesogen group of the liquid crystal compound in a state where the liquid crystal compound exhibits liquid crystallinity, and Curing the urethanization reaction product in a state where the urethanization reaction is performed, and dispersing the filler in the liquid crystal polyurethane elastomer produced by the urethanization reaction.

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