Composition including polyrotaxane and product including the same

Abstract

A composition includes a polyrotaxane (A) which includes cyclodextrin as a ring molecule and polyethylene glycol as a linear molecule, and in which a blocking group is arranged at both ends of the linear molecule; a block copolymer (B) including polysiloxane; and a polymer (C) including no polysiloxane.

Claims

1. A composition comprising: 10 parts by mass of a polyrotaxane (A) which includes cyclodextrin as a ring molecule and polyethylene glycol as a linear molecule, and in which a blocking group is arranged at both ends of the linear molecule; 4 parts by mass to 16 parts by mass of a block copolymer (B) including polysiloxane as a crosslinking agent for the polyrotaxane; and 7 parts by mass to 11 parts by mass of a polymer (C) including no polysiloxane, wherein the block copolymer (B) including polysiloxane has blocked isocyanate groups at its ends, and wherein the polymer (C) including no polysiloxane has blocked isocyanate groups at its ends.

2. The composition according to claim 1, wherein, in the polyrotaxane (A), at least a part of hydroxy groups in the cyclodextrin is substituted with a substituent having a graft chain.

3. The composition according to claim 2, wherein the graft chain is formed by ring-opening polymerization of lactone monomers.

4. The composition according to claim 1, wherein the block copolymer (B) including polysiloxane is a polyester-polysiloxane block copolymer.

5. The composition according to claim 4, wherein the polyester-polysiloxane block copolymer is a polycaprolactone-polydimethylsiloxane block copolymer.

6. The composition according to claim 1, wherein the polymer (C) including no polysiloxane is at least a copolymer selected from polyether and polyester.

7. A cured product comprising the composition as claimed in claim 1, wherein ring molecules of polyrotaxanes (A) are bonded to each other at crosslinking parts, and at least a part of the crosslinking parts is the block copolymer (B) including polysiloxane.

8. A cured film comprising the cured product as claimed in claim 7.

9. A dielectric sheet with electrode layers comprising the cured film as claimed in claim 8 serving as a dielectric material, wherein an electrode layer is attached to opposite surfaces of the cured film.

10. The dielectric sheet with electrode layers according to claim 9, wherein a dielectric breakdown electric field strength of the dielectric sheet with electrode layers at normal temperature and normal humidity after being left under conditions at a temperature of 60 C. and a relative humidity of 90% for 500 hours is 90% or higher, relative to a dielectric breakdown electric field strength of the dielectric sheet with electrode layers at normal temperature and normal humidity immediately after preparation.

11. An actuator comprising the dielectric sheet with electrode layers as claimed in claim 9.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a view schematically illustrating each structure of the polyrotaxane (A), the block copolymer (B), the block copolymer (B) having terminally blocked isocyanate groups, and the polymer (C) prepared in Examples;

(2) FIG. 2 is a view schematically illustrating a structure of the cured film (crosslinked product) prepared in Examples;

(3) FIG. 3 is an explanatory view illustrating a dielectric breakdown test method of the cured film prepared in Examples;

(4) FIG. 4A is a perspective view of a dielectric sheet with electrode layers for measurement of physical properties prepared in Examples and FIG. 4B is an explanatory view illustrating the dielectric breakdown test method;

(5) FIG. 5 is a perspective view of the dielectric sheet with electrode layers for an actuator prepared in Examples; and

(6) FIG. 6A is a sectional view of the actuator prepared in Examples and FIG. 6B is a sectional view of the actuator deformed in an elongated state.

DESCRIPTION OF EMBODIMENTS

(7) [1] Composition Including Polyrotaxane

(8) (a) Polyrotaxane (A)

(9) Examples of cyclodextrins included in the ring molecules include -cyclodextrin, -cyclodextrin, and -cyclodextrin. Part of OH groups in the cyclodextrin may be substituted with other groups such as SH, NH.sub.2, COOH, SO.sub.3H, PO.sub.4H or, as described above, may be substituted with the substituents having graft chains (for example graft chains made by ring-opening polymerization of lactone monomers). Other ring molecules may be included in the ring molecules together with the cyclodextrin. Examples of the other ring molecules include crown ethers, cyclophanes, calixarenes, cucurbiturils, and cyclic amides.

(10) In the linear molecule, other linear molecules may be included together with polyethylene glycol. The other linear molecules are not particularly limited and examples of the other linear molecules include polylactic acid, polyisoprene, polyisobutylene, polybutadiene, polypropylene glycol, polytetrahydrofuran, polydimethylsiloxane, polyethylene, polypropylene, polyvinyl alcohol, and polyvinyl methyl ether.

(11) The blocking group is not particularly limited and examples of the blocking group include dinitrophenyl groups, cyclodextrins, adamantane groups, trityl groups, fluoresceins, pyrenes, substituted benzenes (examples of the substituents include alkyl group, alkyloxy group, hydroxy group, halogen atom, cyano group, sulfonyl group, carboxyl group, amino group, and phenyl group. One or more of the substituents may be included), optionally substituted polynuclear aromatic compounds (as the substituents, the same as above can be exemplified. One or more of the substituents may be included.), and steroids. The blocking group is preferably selected from the group consisting of the dinitrophenyl groups, the cyclodextrins, the adamantane groups, the trityl groups, the fluoresceins, and the pyrenes. The blocking group is more preferably the adamantane groups or the trityl groups.

(12) (b) Block Copolymer (B) Including Polysiloxane

(13) The polysiloxane is not particularly limited and examples of the polysiloxane include polydimethylsiloxane, polymethylphenylsiloxane, and polydimethylsiloxane in which a part of the side chain is modified.

(14) The block copolymer including the polysiloxane is not particularly limited and examples of the block copolymer include polycaprolactone-polysiloxane block copolymers, polyadipate-polysiloxane block copolymers, and polyethylene glycol-polysiloxane block copolymers.

(15) Preferable block copolymers including polysiloxane are as described above.

(16) (c) Polymer (C) Including No Polysiloxane

(17) The polymer including no polysiloxane is not particularly limited and examples of the polymer include polypropylene glycol, polytetramethylene glycol, polycarbonate, polycaprolactone, polyethylene adipate, polybutylene adipate, and copolymers thereof.

(18) Preferable polymers including no polysiloxane are as described above.

(19) [2] Cured Product

(20) The shape of the cured product is not particularly limited and examples of the shape include a linear shape, a strip-like shape, a film-like shape (the cured film), a ring-like shape, a rod-like shape, and a bulk shape. The dimension of the cured product is not particularly limited.

(21) [3] Cured Film

(22) The dimension of the cured film is not particularly limited. In the case of the cured film for an actuator, the thickness of the cured film is preferably 0.02 mm to 0.1 mm. The cured film having a thickness of less than 0.02 mm causes crawling of molded articles. The cured film having a thickness of more than 0.1 mm makes the cured film difficult to deform.

(23) [4] Dielectric Sheet with Electrode Layers

(24) The electrode layers are not particularly limited and examples of the electrode layers may include elastic electrode layers formed by applying a conductive polymer liquid of a silicone or natural rubber, in which conductive particles such as platinum and carbon are dispersed, onto opposite surfaces of the cured film and curing the applied conductive polymer liquid.

(25) Preferable physical properties of the dielectric sheet with electrode layers are as described above.

(26) [5] Actuator

(27) A method of using the dielectric sheet with electrode layers in the actuator is not particularly limited and examples of the actuator include a cylindrical actuator formed by spirally winding the dielectric sheet with electrode layers a plurality of times (for example 6 times) and a curtain-like actuator formed by bending the dielectric sheet with electrode layers in a wave-like form and folding the bent dielectric sheet with electrode layers.

Examples

(28) Hereinafter, Examples of compositions including a polyrotaxane and products including the compositions that embody the present invention will be described in the following order. The present invention, however, is not limited to Examples.

(29) <1> Preparation of polyrotaxane (A)

(30) <2> Preparation of block copolymer (B) including polysiloxane

(31) <3> Preparation of polymer (C) including no polysiloxane

(32) <4> Preparation of composition

(33) <5> Preparation of cured film

(34) <6> Measurement of physical properties of cured film

(35) <7> Preparation of dielectric sheet with electrode layers for measurement of physical properties and measurement of physical properties

(36) <8> Preparation of dielectric sheet with electrode layers for actuator

(37) <9> Preparation of actuator

(38) <1> Preparation of Polyrotaxane A

(39) First, as the polyrotaxane formed by including cyclodextrin as a ring molecule, including polyethylene glycol as a linear molecule, and arranging blocking groups at both ends of the linear molecule, a polyrotaxane modified with a hydroxypropyl group (hereinafter may be abbreviated as HAPR) described in WO 2005/080469 (Patent Document 1) was prepared.

(40) Subsequently, in order to obtain solubilization and compatibility, a polyrotaxane having caprolactone groups was prepared. Into a three-necked flask, 10 g of HAPR was charged and 45 g of -caprolactone was introduced while nitrogen was slowly flowed. The resultant mixture was stirred with a mechanical stirrer at 100 C. for 30 minutes to form a homogeneous solution and thereafter the reaction temperature was raised to 130 C. 0.32 g of tin 2-ethylhexanoate (50% by weight solution) previously diluted with toluene was added and the resultant solution was reacted for 5 hours. The solvent was removed from the reacted solution to give 55 g of the polyrotaxane A having caprolactone groups (hereinafter, may be abbreviated as HAPR-g-PCL). The structure of the polyrotaxane A (HAPR-g-PCL) is schematically illustrated in the first row of FIG. 1. A weight average molecular weight Mw of 580,000 and a molecular weight distribution Mw/Mn of 1.5 were ascertained by GPC.

(41) <2> Preparation of Block Copolymer B Including Polysiloxane

(42) The block copolymer B was prepared by the following two steps.

(43) <2-1> Preparation of Block Copolymer B of polycaprolactone-polydimethylsiloxane-polycaprolactone

(44) Into a 500 ml three-necked recovery flask, polydimethylsiloxane (100 g) modified with carbinol at both ends and -caprolactone (200 g) were charged, and thereafter the resultant solution was stirred for 2 hours in an oil bath of 110 C. under nitrogen flow. To this solution, tin 2-ethylhexanoate (200 mg) was added, and thereafter stirred for 6 hours in an oil bath of 130 C. under nitrogen flow to give the block copolymer B of polycaprolactone-polydimethylsiloxane (PDMS)-polycaprolactone. The structure of the block copolymer B is schematically illustrated in the second row of FIG. 1.

(45) <2-2> Preparation of Block Copolymer B of polycaprolactone-polydimethylsiloxane-polycaprolactone Having Terminally Blocked Isocyanate Groups

(46) Into a three-necked recovery flask, TAKENATE 600 (31.6 g, manufactured by Mitsui Chemicals, Inc.) was charged, and thereafter was stirred in an oil bath of 80 C. under nitrogen flow. To this solution, the block copolymer B of polycaprolactone-polydimethylsiloxane-polycaprolactone (152.69 g) dissolved in toluene (152.69 g) was slowly added dropwise for 2 hours and the resultant solution was further stirred for 2 hours. After the reaction, the liquid temperature of the solution was lowered to room temperature. Thereafter, 2-butanone oxime (22.87 g) was slowly added dropwise so that the liquid temperature did not reach 60 C. or higher. After completion of adding 2-butanone oxime dropwise, the resultant solution was further stirred for 3 hours under room temperature to give the block copolymer B of polycaprolactone-polydimethylsiloxane-polycaprolactone having terminally blocked isocyanate groups. The structure of the block copolymer B is schematically illustrated in the third row of FIG. 1.

(47) <3> Preparation of polymer C including no polysiloxane

(48) Into a three-necked recovery flask, TAKENATE 600 (91.57 g, manufactured by Mitsui Chemicals, Inc.) was charged, and thereafter was stirred in an oil bath of 80 C. under nitrogen flow. To this solution, diol-type polypropylene glycol 700 (110 g) was slowly added dropwise for 2 hours and thereafter the resultant solution was further stirred for 2 hours. After the reaction, the liquid temperature was lowered to room temperature.

(49) Thereafter, 2-butanone oxime (76.58 g) was slowly added dropwise so that the liquid temperature did not reach 60 C. or higher. After completion of adding the 2-butanone oxime dropwise, the resultant solution was further stirred for 8 hours under room temperature to give the polypropylene glycol C having terminally blocked isocyanate groups. The structure of the polypropylene glycol C is schematically illustrated in the fourth row of FIG. 1.

(50) <4> Preparation of Composition

(51) Compositions in Examples 1, 2, and 3 were prepared by the polyrotaxane A (HAPR-g-PCL), the block copolymer B including polysiloxane, the polymer C including no polysiloxane, and other components in formulations listed in Table 1 (formulation values are represented in parts by mass). Compositions in Comparative Example 1 in which the block copolymer B was not included and Comparative Example 2 in which PDMS diol was included rather than the block copolymer B were also prepared.

(52) As a catalyst for deprotection, dibutyltin dilaurate was used. As a silicone additive, DBL-C31 (silicone modified with alcohol at both ends:

(53) caprolactone-dimethylsiloxane-caprolactone block copolymer) manufactured by GELEST Inc. was used. As an antioxidant, IRGANOX1726 (2,4-bis(dodecylthiomethyl)-6-methylphenol) manufactured by BASF SE was used.

(54) TABLE-US-00001 TABLE 1 Comparative Comparative Example 1 Example 2 Example 3 Example 1 Example 2 Components of Composition Polyrotaxane A 10 10 10 10 10 Polysiloxane block copolymer B 4.9 10.6 15.5 Polymer C 10.5 9 7.7 11.8 10.5 Polypropylene glycol diol 4.7 4.7 4.7 4.7 4.7 Polydimethylsiloxanediol 4.9 Methyl cellosolve 25.9 25.3 24.7 26.5 25.9 Dibutyltin dilaurate 0.014 0.015 0.017 0.013 0.014 DBL-C31 0.14 0.15 0.17 0.13 0.14 IRGANOX1726 0.42 0.45 0.47 0.4 0.42 Physical Properties of Cured Film Contents of Polydimethylsiloxane (wt %) 2.66 5.19 7.11 0.25 4.95 Dielectric breakdown electric field strength (V/m) 90.2 89.8 83.4 90.5 Uniform film At normal temperature, Immediately after preparation cannot be obtained Dielectric breakdown electric field strength (V/m) 88.5 81.8 88.7 69.8 60 C., RH = 90%, After 100 hours Dielectric breakdown electric field strength (V/m) 67.6 83.8 87.5 33.6 60 C., RH = 90%, After 500 hours Characteristics of Dielectric Sheet with Electrode Layers Initial characteristics, Electrostatic capacitance (pF) 533 519 502 550 Dielectric breakdown electric field strength (V/m) 66.9 74 68.2 70.6 At normal temperature, Immediately after preparation[1] Dielectric breakdown electric field strength (V/m) 63.6 73.5 64.4 50.86 60 C., RH = 90%, After 500 hours[2] [2]/[1] 100 (%) 95.1 99.3 94.4 72.0

(55) A crosslinking agent solution containing A, B, and C was dissolved in the solvent and stirred to form a homogeneous solution. To this solution, dibutyltin dilaurate, DBL-C31, and IRGANOX1726 were added and the resultant mixture was further stirred to prepare the uniform solution of the composition.

(56) <5> Preparation of Cured Film (Crosslinked Product)

(57) The solution of the composition prepared in <4> was sufficiently defoamed and thereafter applied onto a polypropylene sheet by a slit die coater method. Thereafter, the applied solution was cured by placing in an oven of 130 C. for 5 hours under reduced pressure. The cured product was peeled off from the polypropylene sheet to prepare the cured film having a thickness of 0.05 mm. By infrared spectroscopy, it was ascertained from the decrease in the peak derived from the OH groups in HAPR-g-PCL that the OH groups in HAPR-g-PCL reacted with the isocyanate groups in the block copolymer of polycaprolactone-polydimethylsiloxane-polycaprolactone having terminally blocked isocyanate groups to form crosslink in the cured film. The cured film had elasticity of elastically deforming in a direction along the face of the cured film. The structure of the cured film is schematically illustrated in FIG. 2.

(58) <6> Measurement of Physical Properties of Cured Film

(59) For the cured film (crosslinked product) prepared in <5> immediately after the preparation, the cured film after being left under the environment at a temperature of 60 C. and a relative humidity (RH) of 90% for 100 hours, and the cured film after being left under the same environment for 500 hours, dielectric breakdown electric field strength under normal temperature and normal humidity was measured by the following methods. The measured values are listed in Table 1.

(60) As illustrated in FIG. 3, the cured film 1 was attached to a circular electrode 21 on the installation side. A cylinder electrode 22 was mounted on the cured film 1. At this time, the sample was very carefully prepared so that air bubbles did not remain between the cured film 1 and each of the electrodes 21 and 22 and the sample was further degassed by vacuum equipment. The sample was set in dielectric breakdown measurement apparatus under normal temperature and normal humidity and voltage was applied between the electrodes 21 and 22 by a power source 23 so as to increase the voltage at a voltage increase rate of 10 V/0.1 second. Through an insulation state that substantially no electric current flows, the dielectric breakdown electric field strength (V/m) was determined from the voltage at the time when the electric current becomes 1.2 A or more. The normal temperature means 20 C.15 C. and the normal humidity means 65%20% (JIS-8703, these definitions are the same in the present specification).

(61) <7> Preparation of Dielectric Sheet with Electrode Layers for Measurement of Physical Properties and Measurement of Physical Properties

(62) A mask (not illustrated) including a hole having a diameter of 20 mm was attached to both of the surfaces of the cured film immediately after preparation in <5> and an organic solvent solution of a silicone rubber in which carbon particles were dispersed was applied to both of the surfaces through the hole by spray application. The applied solution was crosslinked and cured to form the electrode layers 2 and 3 having a thickness of 0.02 mm and thus to prepare a dielectric sheet with electrode layers 4 for measuring physical properties as illustrated in FIG. 4A. For the dielectric sheet with electrode layers 4 immediately after formation of the electrode layers 2 and 3 and the dielectric sheet with electrode layers 4 with the electrode layers 2 and 3 formed in the same way and after being left under conditions at a temperature of 60 C. and a relative humidity (RH) of 90% for 500 hours, the dielectric breakdown electric field strength under normal temperature and normal humidity was measured by the following method. The measured values are listed in Table 1.

(63) As illustrated in FIG. 4B, a polycarbonate substrate 25 having a hole 24 was prepared and the electrode layers 2 and 3 were placed inward of the hole 24. The cured film 1 around the electrodes was bonded to the substrate 25 with an adhesive. By the power source 23, voltage was applied between the electrode layers 2 and 3 so as to increase the voltage at a voltage increase rate of 10 V/0.1 second. The dielectric breakdown electric field strength (V/m) was determined in a similar manner to <6>.

(64) <8> Preparation of Dielectric Sheet with Electrode Layers for Actuator

(65) The dielectric sheet with electrode layers for an actuator, which has a structure described in JP 5247123 B (Patent Document 3), was prepared by using the cured film having elasticity, which was prepared in <5>.

(66) As illustrated in FIG. 5, an elastic dielectric sheet with electrode layers 4 was prepared by applying the same organic solvent solution of a silicone rubber in which carbon particles were dispersed as the solution of <7>, onto both of the surfaces of the cured film 1 having a thickness of 0.05 mm by slit die coater method and crosslinking and curing the applied solution to form elastic electrode layers 2 and 3 having a thickness of 0.02 mm and then covering the electrode layers 2 and 3 with elastic insulating layers (not illustrated). When the dielectric sheet with electrode layers 4 is used for the actuator 10 described below, the electrode layer 2 is connected to the positive side and the electrode layer 3 is connected to the negative side. The cured film 1 serving as the dielectric layer is deformed to elongate in a direction along the face of the cured film 1 in response to the voltage application to the electrode layers 2 and 3 and is restored to the original state in response to the stop of the voltage application, whereby the dielectric sheet with electrode layers 4 is reciprocated.

(67) <9> Preparation of Actuator

(68) As illustrated in FIG. 6A, an actuator 10 was prepared by spirally winding the dielectric sheet with electrode layers 4 prepared in <8> a plurality of times (6 times, in the illustrated example) to form a cylindrical product, fixing nuts 5 and 6 on the inner circumference surface of the dielectric sheet with electrode layers 4 at both ends in a direction of the centerline of the dielectric sheet with electrode layers 4, and arranging a coil spring 7 inside the dielectric sheet with electrode layers 4 so that the nuts 5 and 6 were biased in a direction away from each other by the elastic force of the coil spring 7. Thus, the actuator 10 is biased by the elastic force of the coil spring 7 so as to extend in a direction of the centerline of the dielectric sheet with electrode layers 4. The actuator 10 extends as illustrated in FIG. 6A and FIG. 6B when voltage is applied to the electrode layers 2 and 3 and the dielectric sheet with electrode layers 4 elastically deforms to elongate as described above. When the voltage application stops, the dielectric sheet with electrode layers 4 is restored as described above and the actuator 10 is restored to the original state as illustrated in FIG. 6A. The actuator 10 utilizes this displacement amount for driving a driven body (not illustrated) connected to the nuts 5 and 6.

(69) As described above, according to Examples 1, 2, and 3, when cyclodextrins of polyrotaxanes (A) are bonded to each other at crosslinking parts, at least a part of the crosslinking parts forms the block copolymer (B) including polysiloxane and thus the polysiloxane (silicone component) can be included in the cured film 1 in high content (refer to the contents of polydimethylsiloxane in Table 1). The siloxane content is preferably 0.5% by weight to 10% by weight relative to the weight of nonvolatile matter in the composition (=weight in the cured film). Preferably, the content is 3% by weight to 10% by weight. In Comparative Example 2, an attempt was made to prepare a cured film containing the silicone component in high content, but a uniform cured film was not able to be obtained.

(70) In Examples 1, 2, and 3, due to the silicone component contained in high content, the cured film 1 became hydrophobic to make water molecules difficult to mix. This reduced occurrence of the hydrolysis reaction or the like and improved moisture resistance (refer to physical properties of the cured films in Table 1). The dielectric breakdown electric field strength of the dielectric sheet with electrode layers 4 after being left under conditions at a temperature of 60 C. and a relative humidity of 90% for 500 hours relative to that of the dielectric sheet with electrode layers 4 formed by attaching the electrode layers 2 and 3 to the cured film 1 immediately after preparation was 94% or higher, which was excellent (refer to the physical properties of the dielectric sheet with electrode layers in Table 1). The dielectric breakdown electric field strength of the dielectric sheet with electrode layers 4 was preferably 60 V/m or more and Examples 1, 2, and 3 satisfied this criterion even after 500 hours.

(71) The polypropylene glycol C serving as the polymer (C) including no polysiloxane has high compatibility with the polyrotaxane. By including the polypropylene glycol C, a high dielectric constant and a low elasticity were achieved.

(72) The present invention is not limited to Examples and can be appropriately modified without departing from the scope of the present invention to be put into practice.