JP2017152519A - Conversion material and conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a conversion material ensuring excellent conversion characteristics.SOLUTION: A conversion material contains a polyurethane compound that is a reactant of a polyol compound and a polyisocyanate compound, and the polyol compound contains a polyisoprene compound where at least one of two terminal groups is hydroxyl. The weight-average molecular weight of the polyisoprene compound is 6000-10000, and the hydroxyl value (mgKOH/g) of the polyisoprene compound is 40-60 mgKOH/g.SELECTED DRAWING: None

Description

  The present invention relates to a conversion material containing a dielectric elastomer and a conversion element that converts a physical quantity using the conversion material.

  As a conversion element having excellent physical quantity conversion efficiency, a conversion element (dielectric transducer) using a conversion material containing a dielectric elastomer has attracted attention.

  The conversion element includes two electrodes and a conversion layer disposed between the two electrodes and including a conversion material. In this conversion element, when a potential difference is generated between two electrodes, an electrostatic force (Coulomb force) is generated. Therefore, the dielectric elastomer contained in the conversion layer is deformed (stretched and contracted) by using the electrostatic force. . An arbitrary physical quantity is converted into another physical quantity by utilizing the deformation of the dielectric elastomer.

  Various studies have been made on the respective configurations of the conversion material and the conversion element. Specifically, in order to realize an actuator having a large amount of deformation, urethane rubber or the like whose main chain includes isoprene is used as a polymer (dielectric elastomer) (see, for example, Patent Documents 1 to 4).

Japanese Patent Laid-Open No. 02-035786 JP 08-335726 A JP 2003-282882 A JP 2010-233429 A

  Since it is desired to further improve the conversion characteristics of the conversion element, there is still room for improvement with respect to the configurations of the conversion material and the conversion element.

  An object of the present invention is to provide a conversion material and a conversion element capable of obtaining excellent conversion characteristics.

  As a result of intensive investigations to achieve the above-mentioned object, the present inventor has optimized the composition and physical properties of the dielectric elastomer for the conversion material containing the dielectric elastomer and the conversion element using the conversion material. The inventors have found that the above-mentioned problems can be solved.

  The present invention has been made on the basis of the above knowledge, and the conversion material of one embodiment of the present invention includes a dielectric elastomer, and the dielectric elastomer is a reaction product of a polyol compound and a polyisocyanate compound. A certain polyurethane compound is included. This polyol compound includes a polyisoprene compound in which at least one of two terminal groups is a hydroxyl group (—OH). The weight average molecular weight of the polyisoprene compound is 6000 or more and 10,000 or less, and the hydroxyl value (mgKOH / g) of the polyisoprene compound is 40 mgKOH / g or more and 60 mgKOH / g or less.

  A conversion element according to an embodiment of the present invention includes a first electrode, a second electrode, and a conversion layer that is disposed between the first electrode and the second electrode and includes a conversion material. The material has the same configuration as that of the conversion material according to the embodiment of the present invention described above.

  According to the conversion material or conversion element of one embodiment of the present invention, since the dielectric elastomer contained in the conversion material has the above-described composition and physical properties, excellent conversion characteristics can be obtained.

It is sectional drawing showing the structure of the conversion element in one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described in detail. The order of explanation is as follows. However, details regarding one embodiment of the present invention are not limited to the modes described below, and can be changed as appropriate.

1. 1. Conversion material 1-1. Configuration 1-2. Operation 1-3. Action and effect Applications of conversion materials (conversion elements)

<1. Conversion material>
First, the conversion material of one embodiment of the present invention will be described.

  The conversion material described here includes a dielectric elastomer that can be deformed (stretched and shrunk) using strain generated in response to an electric field. This conversion material is used in applications such as converting physical quantities using the deformation of the dielectric elastomer described above. The application of the conversion material is not particularly limited. An example of the use of the conversion material will be described later.

<1-1. Configuration>
The conversion material includes one or more of dielectric elastomers.

[Dielectric elastomer]
The dielectric elastomer includes a polyurethane compound that is a reaction product of a polyol compound and a polyisocyanate compound. That is, the polyurethane compound is a cured reaction product of a polyol compound and a polyisocyanate compound.

  “Polyol compound” is a general term for compounds having two or more hydroxyl groups (—OH). The “polyisocyanate compound” is a general term for compounds having two or more isocyanate groups (—N═C═O).

  In addition, the kind of polyol compound may be only one kind, and may be two or more kinds. Moreover, the kind of polyisocyanate compound may be only one kind, and may be two or more kinds. For this reason, only one type of polyurethane compound may be used, or two or more types may be used.

  The polyol compound contains a polyisoprene compound in which at least one of the two end groups is a hydroxyl group. That is, the polyisoprene compound is a compound in which one or both of the two end groups are substituted with a hydroxyl group in a polyisoprene having two end groups, and is a so-called polyisoprene derivative.

  In this polyisoprene compound, only one of the two end groups may be a hydroxyl group, or both of the end groups may be a hydroxyl group. That is, the polyisoprene compound has a maximum of two hydroxyl groups in one molecule.

  In the case where only one of the two end groups is a hydroxyl group, the type of the other end group is not particularly limited. The other terminal group may be, for example, a hydrogen group, a monovalent hydrocarbon group, or another group. The monovalent hydrocarbon group is, for example, an alkyl group.

Since the polyol compound contains a polyisoprene compound, the polyurethane compound contains an isoprene skeleton (—CH ₂ —C (—CH ₃ ) ═CH—CH ₂ —) in the repeating unit. Hereinafter, a polyurethane compound containing an isoprene skeleton in a repeating unit is referred to as an “isoprene-based polyurethane compound”.

  The reason why the polyol compound contains the isoprene-based polyurethane compound is that the deformability of the dielectric elastomer is improved.

  Specifically, as the types of polyurethane compounds, in addition to the isoprene-based polyurethane compounds formed using the polyisoprene compounds described above, other polyurethane compounds formed using other compounds than the polyisoprene compounds include Can be mentioned.

Another compound is, for example, a polybutadiene compound. The “polybutadiene compound” is a compound (polybutadiene derivative) in which one or both of the two end groups are substituted with a hydroxyl group in polybutadiene having two end groups. When the polyol compound contains a polybutadiene compound, the polyurethane compound contains a butadiene skeleton (—CH ₂ —CH═CH—CH ₂ —) in the repeating unit. Hereinafter, a polyurethane compound containing a butadiene skeleton in the repeating unit is referred to as a “butadiene-based polyurethane compound”.

  Another compound is, for example, polyalkylene glycol. Although the kind of this polyalkylene glycol is not specifically limited, For example, it is polypropylene glycol etc. Hereinafter, a polyurethane compound formed using polyalkylene glycol is referred to as “glycol-based polyurethane compound”.

  However, other polyurethane compounds represented by the above-mentioned butadiene-based polyurethane compounds and glycol-based polyurethane compounds do not have sufficient deformability. Therefore, the deformability of dielectric elastomers containing other polyurethane compounds is not sufficiently high.

  On the other hand, the deformability of the isoprene-based polyurethane compound is superior to the deformability of the other polyurethane compounds described above. Therefore, the deformability of the dielectric elastomer containing the isoprene-based polyurethane compound is sufficiently high.

  In particular, the physical properties of the polyisoprene compound are optimized in order to sufficiently improve the deformability of the dielectric elastomer. Specifically, the weight average molecular weight of the polyisoprene compound is 6000 to 10,000. Moreover, the hydroxyl value (mgKOH / g) of the polyisoprene compound is 40 mgKOH / g to 60 mgKOH / g. Thereby, in the dielectric elastomer containing the isoprene-based polyurethane compound, remarkably high deformability can be obtained as compared with the dielectric elastomer containing other polyurethane compounds.

  In addition, the polyol compound may contain any 1 type or 2 or more types of other compounds with the above-mentioned polyisoprene compound.

  The type of the other compound is not particularly limited as long as it is a compound having two or more hydroxyl groups (excluding the polyisoprene compound described above), and examples thereof include a glycol compound. This is because the deformability of the dielectric elastomer is further improved.

  Although the kind of glycol compound is not specifically limited, For example, it is polytetramethylene ether glycol etc. This is because the deformability of the dielectric elastomer is sufficiently improved as compared with the case where the polyol compound contains only the polyisoprene compound.

  The kind of polyisocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups as described above.

  Among these, the polyisocyanate compound is preferably a diisocyanate compound having two isocyanate groups. Since the above-mentioned polyisoprene compound has a maximum of two hydroxyl groups in one molecule, when a diisocyanate compound having two isocyanate groups is used as the polyisocyanate compound, the polyisoprene compound and the diisocyanate compound are likely to react. Because it becomes.

  The type of the diisocyanate compound is not particularly limited, and examples thereof include diphenylmethane diisocyanate and hexamethylene diisocyanate.

[Other materials]
In addition, the conversion material may contain any 1 type or 2 or more types of other materials with the above-mentioned dielectric elastomer.

  Although the kind of other material is not specifically limited, For example, they are a catalyst, surfactant, etc.

  The catalyst is a so-called curing catalyst and mainly serves to smoothly and sufficiently advance the reaction between the polyol compound and the polyisocyanate compound. Although the kind of catalyst is not specifically limited, For example, it is any 1 type in titanium ethyl acetoacetate (titanium diisopropoxybis (ethyl acetoacetate)) etc., or 2 or more types. In addition, since content of the catalyst in conversion material is not specifically limited, it can set arbitrarily.

  The surfactant mainly serves to adjust the surface defects of the coating film. Although the kind of surfactant is not specifically limited, For example, they are any 1 type in a fluorine-containing group and a lipophilic group containing oligomer etc., or 2 or more types. The content of the surfactant in the conversion material is not particularly limited and can be arbitrarily set.

  However, after the reaction between the polyol compound and the polyisocyanate compound, that is, after the formation of the isoprene-based polyurethane compound, the other materials described above may or may not remain in the conversion material. .

<1-2. Operation>
This conversion material operates, for example, as follows. Here, for example, a case where a film-shaped or flat-shaped conversion material is used will be described.

[Exercise movement]
In a state where two electrodes are arranged so as to sandwich the conversion material, when a voltage is applied between the two electrodes, the dielectric elastomer is deformed by using electrostatic force, so that the dielectric elastomer is included. The conversion material is deformed. In this case, the dielectric elastomer contracts in the thickness direction and expands in the plane direction. Thereafter, when the voltage application is stopped, the dielectric elastomer returns to the state before the voltage application. In this case, the dielectric elastomer expands in the thickness direction and contracts in the plane direction.

  Therefore, the conversion material can realize a desired movement operation by utilizing the above-described expansion and contraction of the dielectric elastomer.

[Power generation operation]
In addition, when two electrodes are arranged so as to sandwich the conversion material, the conversion material and the two electrodes function as a kind of variable capacitor whose capacitance changes according to an external force.

  Accordingly, when an external force is supplied to the conversion material, the dielectric elastomer is deformed in accordance with the external force, so that the conversion material including the dielectric elastomer is deformed. In this case, since the dielectric elastomer contracts in the thickness direction and expands in the surface direction, the variable capacitor becomes a high capacity state. Thereafter, when the supply of the external force is stopped, the dielectric elastomer returns to the state before the supply of the external force using its own elastic force. In this case, since the dielectric elastomer expands in the thickness direction and contracts in the surface direction, the variable capacitor is in a low capacity state. This capacitance state change increases the potential difference, which increases the electrostatic energy.

  Therefore, the conversion material can realize a power generation operation using the electrostatic energy described above.

[Detection operation]
Furthermore, when an external force having an arbitrary physical quantity is supplied to the conversion material in a state in which the two electrodes are arranged so as to sandwich the conversion material, the dielectric elastomer is deformed in accordance with the external force, so that the dielectric The conversion material including the elastomer is deformed. Thereby, the electrostatic capacitance between two electrodes changes. Based on this change in capacitance, the supply of external force to the conversion material is detected, and the value (physical quantity) of the external force is specified.

  Therefore, based on the above-described change in capacitance, the conversion material can realize an external force (physical quantity) detection operation.

<1-3. Action and Effect>
In this conversion material, since the polyol compound contained in the dielectric elastomer contains a polyisoprene compound, the polyurethane compound (isoprene-based polyurethane compound) in which the dielectric elastomer is a reaction product of the polyol compound and the polyisocyanate compound. ) Is included. Moreover, the physical properties (weight average molecular weight and hydroxyl value) of the polyisoprene compound described above are optimized. In this case, as described above, since the polyol compound does not contain the polyisoprene compound, the deformability of the conversion material is improved as compared with the case where the dielectric elastomer does not contain the isoprene-based pre-urethane compound. . Therefore, excellent conversion characteristics can be obtained in the conversion element to which the conversion material is applied.

  In particular, if the polyol compound contains a glycol compound, the deformability of the conversion material is further improved, so that a higher effect can be obtained.

<2. Applications of conversion materials (conversion elements)>
Next, the use of the conversion material will be described.

  The application of the conversion material is not particularly limited as long as the application of the conversion material can exhibit a desired function.

  Specifically, the conversion material can be applied to a conversion element that converts an arbitrary physical quantity into another physical quantity. Below, the conversion element which is an application example of a conversion material is demonstrated.

[Constitution]
FIG. 1 shows a cross-sectional configuration of the conversion element. For example, as illustrated in FIG. 1, the conversion element includes a first electrode 1, a second electrode 2, and a conversion layer 3 disposed between the first electrode 1 and the second electrode 2. Yes.

  In addition, each planar shape of the 1st electrode 1, the 2nd electrode 2, and the conversion layer 3 is not specifically limited. That is, the planar shape may be a circle, a rectangle, or any other shape.

(First electrode and second electrode)
The first electrode 1 and the second electrode 2 face each other with the conversion layer 3 interposed therebetween. The forming material of each of the first electrode 1 and the second electrode 2 is not particularly limited. Specifically, each of the first electrode 1 and the second electrode 2 includes any one type or two or more types of conductive materials such as a carbon material, a conductive polymer compound, and a metal material, for example. Yes. Examples of the carbon material include graphite, fullerene, carbon nanotube (CNT), graphene, and the like. The carbon material may be subjected to any one type or two or more types of processes such as a metal doping process, a metal inclusion process, and a metal plating process. Examples of the conductive polymer compound include polyacetylene, polythiophene, polypyrrole, polyphenylene, polyphenylene vinylene, and polybenzothiazole. Examples of the metal material include silver (Ag), gold (Au), and aluminum (Al), and may be an alloy. However, the forming material of the first electrode 1 and the forming material of the second electrode 2 may be the same or different.

  Each of the first electrode 1 and the second electrode 2 can be deformed according to deformation (extension and contraction) of the conversion layer 3 in order to facilitate the operation of the conversion element (deformation of the conversion layer 3). . In other words, each of the first electrode 1 and the second electrode 2 has so-called flexibility (stretchability).

  The thicknesses of the first electrode 1 and the second electrode 2 are not particularly limited. Further, each of the first electrode 1 and the second electrode 2 may be a single layer or a multilayer.

  Here, the 1st electrode 1 is adjacent to a part of surface (upper surface) of the conversion layer 3, for example. Moreover, the 2nd electrode 2 is adjacent to a part of surface (lower surface) of the conversion layer 3, for example.

(Conversion layer)
The conversion layer 3 contains any one type or two or more types of the conversion materials described above. The thickness of the conversion layer 3 is not particularly limited. Since details of the conversion material have already been described, the description thereof is omitted here.

[Operation]
This conversion element operates as follows, for example, using the operation of the conversion material described above.

  When using the motion of the conversion material, when a voltage is applied between the first electrode 1 and the second electrode 2, the conversion layer 3 (dielectric elastomer) contracts in the thickness direction and the surface direction. Stretch to. Thereafter, when the application of the voltage is stopped, the conversion layer 3 expands in the thickness direction and contracts in the surface direction. When the conversion layer 3 is deformed, the first electrode 1 and the second electrode 2 are also deformed (stretched and contracted) in accordance with the deformation (extension and contraction) of the conversion layer 3.

  Therefore, the conversion element converts electrical energy into mechanical (kinetic) energy by using the motion of the conversion layer 3. As a result, various motion functions are realized using a protruding operation, a retreating operation, a reciprocating (vibrating) operation, a rotating operation, and the like.

  When using the power generation operation of the conversion material, when an external force is supplied to the conversion element, the conversion layer 3 (dielectric elastomer) expands in the surface direction and contracts in the thickness direction according to the external force. Charge is stored in the conversion layer 3. Thereafter, when the supply of the external force is stopped, the conversion layer 3 contracts in the surface direction and expands in the thickness direction, so that a potential difference (electrostatic energy) is generated between the first electrode 1 and the second electrode 2. Occur. By repeating the deformation operation (extension and contraction) of the conversion layer 3, the electrostatic energy increases.

  Thus, the conversion element converts mechanical energy into electrical energy. Thereby, the power generation function is realized by using the power generation operation of the conversion layer 3.

  When using the detection operation of the conversion material, when an external force having an arbitrary physical quantity is supplied to the conversion element, the conversion layer 3 (dielectric elastomer) is deformed according to the external force. The capacitance between the second electrode 2 changes. Based on this change in capacitance, the supply of external force to the conversion element is detected, and the value (physical quantity) of the external force is specified.

  Therefore, the conversion element converts an arbitrary physical quantity into electrical energy. Thus, a physical quantity detection function or the like is realized by using the detection operation of the conversion layer 3.

  In FIG. 1, the “thickness direction” is a direction (vertical direction) in which the first electrode 1 and the second electrode 2 are opposed to each other, and the “plane direction” is the thickness described above. It is the direction (left-right direction) that intersects the direction.

[Action and effect]
In this conversion element, since the conversion layer 3 contains the conversion material described above, an excellent deformability can be obtained in the conversion layer 3. Therefore, various functions such as a motion function, a power generation function, and a detection function can be realized by using the deformability of the conversion layer 3.

  Examples of the present invention will be described below. The order of explanation is as follows. However, the aspect of the present invention is not limited to the aspect described here.

1. 1. Production of conversion material 2. Evaluation of conversion material Consideration

<1. Production of conversion materials>
(Experimental Examples 1 to 11)
The conversion material was manufactured by the following procedures. Here, two types of polyol compounds (a first polyol compound and a second polyol compound) were used.

  First, after mixing X part by weight of the first polyol compound, Y part by weight of the second polyol compound, Z part by weight of the polyisocyanate compound, 0.11 part by weight of the catalyst, and 0.5 part by weight of the surfactant. The mixture was stirred to obtain a mixed solution. In addition, as a polyol compound, while using only the 1st polyol compound as needed, the 1st polyol compound and the 2nd polyol compound were used together.

  As the first polyol compound, a hydroxyl-terminated liquid polyisoprene that is a polyisoprene compound (PIP: Polyip from Idemitsu Kosan Co., Ltd.), a hydroxyl-terminated liquid polyolefin that is a polyisoprene compound (PIPR: EPOL from Idemitsu Kosan Co., Ltd.), A glycerin type polypropylene glycol (PPG: G-4000 manufactured by ADEKA Corporation) that is not a polyisoprene compound and a hydroxyl-terminated liquid polybutadiene (PBD: Polybd manufactured by Idemitsu Kosan Co., Ltd.) that is not a polyisoprene compound were used. The hydroxyl group-terminated liquid polyolefin described above is a compound obtained by reducing a hydroxyl group-terminated liquid polyisoprene compound.

  As the second polyol compound, two kinds of glycol compounds were used. Specifically, two kinds of polytetramethylene ether glycols (PTMG1: PTMG-1000 manufactured by Mitsubishi Chemical Corporation and PTMG2: PTMG-2000 manufactured by Mitsubishi Chemical Corporation) were used.

  As the polyisocyanate compound, two kinds of diisocyanate compounds were used. Specifically, diphenylmethane diisocyanate (MDI: manufactured by Tokyo Chemical Industry Co., Ltd.) and hexamethylene diisocyanate (HDI: manufactured by Tokyo Chemical Industry Co., Ltd.) were used.

  As the catalyst, titanium ethyl acetoacetate (Origatix TC-750 manufactured by Matsumoto Fine Chemical Co., Ltd.) was used.

  As the surfactant, a fluorine-containing group / lipophilic group-containing oligomer (Megafac F-554 manufactured by DIC Corporation) was used.

  The mixing ratio X (parts by weight) of the first polyol compound, the mixing ratio Y (parts by weight) of the second polyol compound, the mixing ratio Z (parts by weight) of the polyisocyanate compound, the weight average molecular weight of the first polyol compound and The hydroxyl value (mgKOH / g) is as shown in Table 1. The “IP skeleton” shown in Table 1 represents whether the first polyol compound contains an isoprene skeleton.

  Subsequently, the mixed solution was applied to the surface of a supporting substrate (75 μm thick release PET substrate) using an applicator, and then the mixed solution was heated. This release PET substrate is a PET substrate whose surface has been subjected to a release treatment. The heating conditions were temperature = 120 ° C. and time = 90 minutes. Thereby, since the polyol compound and the polyisocyanate compound reacted, a dielectric elastomer containing a polyurethane compound was formed.

  Finally, the dielectric elastomer was peeled from the substrate. Thereby, a film-like conversion material (thickness = 500 μm) containing a dielectric elastomer was obtained.

<2. Evaluation of conversion materials>
When the deformation characteristics of the conversion material were examined, the results shown in Table 1 were obtained.

  When examining the deformation characteristics, first, a test piece was prepared by punching out the film-like conversion material using a punching machine. In this case, a dumbbell-shaped No. 6 test piece was obtained by complying with JIS6251. Subsequently, after a part of the test piece was sandwiched using the pair of silicone rubber sheets, the pair of silicone rubber sheets was fixed using an autograph screw-type gripping tool. In this case, the deflection of the test piece was removed by adjusting the height of the screw-type gripping tool. Finally, the amount of deformation (mm) at break of the film-like conversion material was measured by pulling the film-like conversion material using a tensile tester. In this case, the tensile speed was 500 mm / min.

<3. Discussion>
As is clear from Table 1, since a polyisoprene compound is not used as the first polyol compound, when the polyurethane compound does not contain an IP skeleton (Experimental Examples 8 to 11), a sufficient amount of deformation cannot be obtained. It was. This polyurethane compound is a butadiene-based polyurethane compound or a glycol-based polyurethane compound.

  On the other hand, since the polyisoprene compound is used as the first polyol compound, when the polyurethane compound contains an IP skeleton (Experimental Examples 1 to 7), the weight average molecular weight is 6000 to 10,000 and the hydroxyl group is When the value was 40 mg KOH / g to 60 mg KOH / g, a sufficient amount of deformation was obtained. This polyurethane compound is an isoprene-based polyurethane compound.

  In particular, when the polyurethane compound contains an IP skeleton, the amount of deformation increased more when the second polyol compound (glycol compound) was used together with the first polyol compound (Experimental Examples 6 and 7).

  From these results, the dielectric elastomer contained in the conversion material contains a reaction product (polyurethane compound) of a polyol compound (polyisoprene compound) and a polyisocyanate compound, and the physical properties (weight average molecular weight) of the polyisoprene compound When the hydroxyl value) is optimized, a sufficient amount of deformation was obtained. Therefore, excellent conversion characteristics were obtained.

  The present invention has been described above with reference to one embodiment and an example. However, the present invention is not limited to the aspect described in the one embodiment and the example, and the aspect may be variously modified.

  Specifically, the conversion material of one embodiment of the present invention is not limited to the conversion element described above, and may be applied to other uses. Even in this case, various operations can be realized by utilizing the excellent deformability of the dielectric elastomer contained in the conversion material.

  DESCRIPTION OF SYMBOLS 1 ... 1st electrode, 2 ... 2nd electrode, 3 ... Conversion layer.

Claims (3)

Including a dielectric elastomer,
The dielectric elastomer includes a polyurethane compound that is a reaction product of a polyol compound and a polyisocyanate compound,
The polyol compound includes a polyisoprene compound in which at least one of two terminal groups is a hydroxyl group (-OH),
The polyisoprene compound has a weight average molecular weight of 6000 or more and 10,000 or less,
The polyisoprene compound has a hydroxyl value (mgKOH / g) of 40 mgKOH / g or more and 60 mgKOH / g or less.
Conversion material. The polyol compound further contains a glycol compound,
The conversion material according to claim 1. A first electrode, a second electrode, and a conversion layer disposed between the first electrode and the second electrode and including a conversion material,
The conversion material includes a dielectric elastomer;
The dielectric elastomer includes a polyurethane compound that is a reaction product of a polyol compound and a polyisocyanate compound,
The polyol compound includes a polyisoprene compound in which at least one of two terminal groups is a hydroxyl group,
The polyisoprene compound has a weight average molecular weight of 6000 or more and 10,000 or less,
The polyisoprene compound has a hydroxyl value (mgKOH / g) of 40 mgKOH / g or more and 60 mgKOH / g or less.
Conversion element.

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