JP6626647B2 - Variable thermal conductivity material, thermal control device using the variable thermal conductivity material, and thermal control method using the variable thermal conductivity material - Google Patents

Description

  The present invention relates to a variable thermal conductivity material, a thermal control device using the variable thermal conductivity material, and a thermal control method using the variable thermal conductivity 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 has as its object to provide a heat conductivity variable material whose heat conductivity changes when the temperature is equal to or higher than a predetermined temperature. In particular, it is an object of the present invention to provide a heat control device and a material for realizing a heat control method having a simple and compact configuration that does not require a cooling device or the like separately from a heat insulating material.

  The present invention is a variable thermal conductivity material whose thermal conductivity changes when the temperature is equal to or higher than a predetermined temperature.

  The heat conductivity variable material of the present invention has a property that the heat conductivity changes when the temperature is equal to or higher than a predetermined temperature. Further, the heat conductivity variable material of the present invention has a characteristic that when the temperature is lower than a predetermined temperature, the heat conductivity returns to its original state. That is, since the thermal conductivity of the variable thermal conductivity material of the present invention changes with temperature, it is possible to switch between the heat insulation function and the heat dissipation function. By using the variable thermal conductivity material as a member of the heat control device, it is possible to provide a heat control device and a heat control method with a simple and compact configuration that do not require a cooling device or the like separately from a heat insulating material. it can.

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

<Thermal conductivity variable material>
The heat conductivity variable material of the present invention changes its heat conductivity at a temperature equal to or higher than a predetermined temperature. In particular, it is preferable that the thermal conductivity variable material of the present invention has a high thermal conductivity when the temperature is equal to or higher than a predetermined temperature. The material used for the thermal conductivity variable material has a high thermal conductivity when the temperature is equal to or higher than a predetermined temperature, and has a low thermal conductivity when the temperature is lower than the predetermined temperature. The material is not particularly limited as long as it returns to In general, as the thickness of the material increases, the thermal conductivity decreases, and as the thickness of the material decreases, the thermal conductivity increases.Therefore, as the material used for the thermal conductivity variable material, a predetermined temperature is used. A material in which the thickness is reduced in the above manner and which returns to the original thickness when the temperature is lower than a predetermined temperature can be exemplified. Note that the larger the difference between the thermal conductivity at a temperature equal to or higher than the predetermined temperature and the heat conductivity at a temperature lower than the predetermined temperature, the greater the switching between the heat insulation performance and the heat radiation performance.

  The material used for the variable thermal conductivity material is not particularly limited as long as the thickness decreases when the temperature is equal to or higher than a predetermined temperature and returns to the original value when the temperature is lower than the predetermined temperature. Examples of the material include a thermoresponsive polymer. Examples of the thermoresponsive polymer include a liquid crystal polyurethane elastomer, a liquid crystal silicone elastomer, a liquid crystal acrylate elastomer, poly N-substituted (meth) acrylamide (for example, poly N-isopropylacrylamide), and polyvinyl ether. It can be 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.

  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 heat conduction is performed. As a material used for the variable rate 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.

  The variable thermal conductivity material may contain a filler in order to improve the breaking strength. The filler to be added only needs to have a reinforcing function, and known fillers can be used without particular limitation.

[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 is characterized in that the temperature range in which liquid crystallinity is exhibited is low. 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 liquid crystal compound to increase the content of the mesogenic group, it is possible to obtain a thermoresponsive material that is greatly deformed by a change in temperature. In the present invention, since the liquid crystal compound is used, the thermoresponsive material obtained even when 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, liquid crystal 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.

  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 heat conductivity 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 heat 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 the heat conductivity 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 is not particularly limited as long as it has a desired heat insulating performance and can change the thermal conductivity of the thermal conductivity variable material by a shape change due to temperature. The voids may be independent of each other or may be continuous. From the viewpoint of easiness of shape change of the thermal conductivity variable material, the closed cell rate is preferably 90% or less, more preferably 80% or less, further preferably 60% or less, and particularly preferably 50% or less. % Or less. The density can be appropriately set according to desired heat insulation performance and heat radiation performance. For example, the density is preferably 0.9 g / cm ³ or less in order to obtain a thermal conductivity variable material having a high thermal conductivity at a predetermined temperature or higher using the liquid crystal elastomer. . In order to increase the amount of change in thermal conductivity, the density is more preferably 0.8 g / cm ³ or less, further preferably 0.6 g / cm ³ or less, and particularly preferably 0.4 g / cm ³ or less. / Cm ³ or less. On the other hand, in order to obtain a heat conductivity variable material having a low heat conductivity at a temperature equal to or higher than a predetermined temperature using the liquid crystal elastomer, the density is preferably greater than 0.9 g / cm ³ , More preferably, it is 0.95 g / cm ³ or more.

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

  The thermal control device 1 has at least the thermal conductivity variable material 2.

  The thermal conductivity variable material 2 is provided so as to cover the periphery of the thermal control target 3. In FIG. 1, the thermal conductivity variable material 2 is provided so as to surround four sides of the thermal control target 3, but is not limited thereto, and may be appropriately changed according to the use environment of the thermal control target 3. It is possible to do.

  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 heat conductivity variable material 2 is deformed and the thickness is reduced. The heat conductivity variable material 2 has a high heat insulating effect because the heat conductivity is low when the thickness is large as shown in FIG. On the other hand, as shown in FIG. 2, when the thickness of the heat conductivity variable material 2 is reduced by heat, the heat conductivity increases, so that the heat insulating effect can be reduced. Further, when the temperature decreases and becomes lower than a predetermined temperature, the thermal conductivity variable material 2 returns to the original state as shown in FIG. The heat control device 1 according to the present embodiment can adjust the heat conductivity and switch between the heat insulation property and the heat dissipation property with the above-described configuration, so that the heat of the heat control target 3 can be controlled. .

  Hereinafter, the variable thermal conductivity material of the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.

<Measurement and evaluation method>
(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)} × 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.

[Performance evaluation of variable thermal conductivity materials]
The evaluation of the thermal conductivity variable material was performed using a device combining a heat flow meter (M55A, 2300A, manufactured by Eto Electric Co., Ltd.) and a rubber heater (Samicon 230, SBX3030K1S).
1) Thermal conductivity The thermal conductivity of the variable thermal conductivity material was measured in the thickness direction of the variable thermal conductivity material by a heat flow meter method according to JISA 1412-2.
2) Rate of change in thickness The rate of change in thickness is defined as 100% when the thickness of the heat conductivity variable material (100 mm long x 100 mm wide x 10 mm thick) at a temperature lower than a predetermined temperature is equal to or higher than a predetermined temperature. Represents the degree of change in the thickness of the variable thermal conductivity material. The thickness change rate was determined by the following equation.
Thickness change rate (%) = (Thickness of variable thermal conductivity material at or above predetermined temperature / thickness of variable thermal conductivity material at below predetermined temperature) × 100
3) Thermal conductivity change rate The thermal conductivity change rate is defined as 100% of the thermal conductivity of the thermal conductivity variable material when the temperature is lower than the predetermined temperature, and the thermal conductivity variable when the temperature is higher than the predetermined temperature. Indicates the degree of change in the thermal conductivity of the 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 variable thermal conductivity material at or above predetermined temperature / thermal conductivity of variable thermal conductivity material at or below predetermined temperature) × 100

[Measurement of density]
A sample of 20 × 20 × 25 mm was cut out from the produced foamed liquid crystal polyurethane elastomer so as not to include a skin layer, and the length of three sides was measured to calculate the volume. Further, the weight of the sample was measured. Then, the density (g / cm ³ ) was calculated from the values of the volume and the weight.

(Measurement of closed cell rate)
A sample having a size of 20 × 20 × 25 mm was cut out from the produced foamed liquid crystal polyurethane elastomer so as not to include a skin layer, and the specific gravity of the sample was measured using an air-comparison hydrometer 930 (manufactured by Beckman). The closed cell rate was calculated by the following formula based on the counter value obtained by the measurement and the sample volume value.
Closed cell rate (%) = 100 × (counter value) / (sample volume value)

<Example 1>
[Synthesis of Mesogendiol as Liquid Crystalline Compound]
BH6 (100 g), 3.8 g of KOH, and 600 ml of DMF were put in a reaction vessel and mixed, and then 8 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＝４である。）

(Where n = 4)

[Synthesis of polyurethane elastomer and preparation of variable thermal conductivity material]
20 g of the mesogendiol, 4.2 g of hexamethylene diisocyanate, 0.6 g of HDI-based isocyanurate (Sumijur N3300, manufactured by Sumika Bayer Urethane Co., Ltd.), and 0.2 g of cyclopentane (manufactured by Tokyo Chemical Industry Co., Ltd., boiling point 49 ° C.) And 0.1 g of a foam stabilizer B-8017 (manufactured by Goldschmidt) at 40 ° C. to obtain a mixture. Thereafter, the mixture was poured into a mold heated to 50 ° C. in advance, and reaction-cured at 50 ° C. for 30 minutes to obtain a semi-cured polyurethane. After demolding from the mold, the polyurethane was uniaxially stretched twice at 20 ° C. Then, while maintaining the state where the polyurethane was stretched twice, it was left standing until it was cured at 0 ° C. to obtain a foamed liquid crystal polyurethane elastomer which changed its shape in the thickness direction.

<Examples 2 to 5>
A foamed liquid crystal 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. HDI in Table 1 is hexamethylene diisocyanate.

  The composition and evaluation results are shown in Tables 1 and 2, respectively.

  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 heat conductivity variable material according to the present invention can be used for a heat control device and a heat control method. For example, it is suitably used for a heat control device and a heat control method for adjusting the temperature of a rechargeable battery mounted on an automobile. can do.

1. Thermal control device 2. Thermal conductivity variable material 3. Thermal control object

Claims (4)

A heat conductivity variable material whose heat conductivity changes when the temperature is equal to or higher than a predetermined temperature,
The thermal conductivity variable 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 an der Ru liquid crystal polyurethane elastomer,
A heat conductivity variable material in which the liquid crystal polyurethane elastomer has an orientation, and when the temperature is equal to or higher than a predetermined temperature, the property of the orientation changes so that the thickness is reduced and the thermal conductivity is increased.   2. The heat conductivity variable material according to claim 1, having a void inside.   A thermal control device using the thermal conductivity variable material according to claim 1. A method for producing a liquid crystal polyurethane elastomer in which the thickness is reduced and the thermal conductivity is increased by changing the nature of the orientation when the temperature is 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 and an isocyanate compound which reacts with the active hydrogen group of the liquid crystal compound is heated to urethane. A step of performing a hydration reaction, a step of uniaxially orienting a mesogen group of the liquid crystal compound in a state where the liquid crystal compound exhibits liquid crystallinity, and a step of orienting the mesogen group in a uniaxial direction while the liquid crystal compound exhibits liquid crystallinity. Curing the urethanization reaction product in a state.

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