Molded body

Abstract

Provided is a molded body which has low compression set and low hardness while having electrical conductivity. The molded body comprises a polyurethane elastomer and a conductive filler; the polyurethane elastomer comprises a matrix containing a specific first structure and a domain dispersed in the matrix; the domains each comprising a second structure different from the first structure; the conductive filler is non-uniformly distributed in the matrix; a parameter A representing a viscoelastic term of the domain and a parameter B representing a viscoelastic term of the substrate, which are determined from a viscoelastic image of a cross section of the molded body obtained by a scanning probe microscope, satisfy a relational expression Alt; b; the content ratio of the conductive filler in the molded body is 0.02-5.0 mass%, and the volume resistivity of the molded body is 1.0 * 109 [Omega] cm or less; and the Young's modulus of the molded body is 0.5 to 4.0 MPa.

Description

Technical Field

[0001] The present disclosure relates to a shaped body comprising a polyurethane elastomer and a conductive filler contained in the polyurethane elastomer. Background Art

[0002] For sensors for detecting deformation of components and the magnitude and distribution of loads acting on components, components for electrophotography, etc., the use of conductive elastomeric materials (conductive elastomers) has been proposed. The conductive elastomers in such applications are required not only to be flexible (low hardness), but also to have a fast recovery property (low compression set) against deformations such as compression set caused by external forces.

[0003] For example, Patent Document 1 discloses a conductive elastomer containing 25 to 55% by volume of a conductive filler relative to a rubber blend formed of silicone rubber and isoprene rubber.

[0004] Patent Document 2 discloses a conductive elastomer containing a polyurethane elastomer and a conductive filler.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. H02-196836

[0008] [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-228597

[0009] Non-Patent Documents

[0010] [Non-Patent Document 1] IEEE Transactions on SYSTEMS, MAN, AND CYBERNETICS, Vol. SMC-9, No. 1, January 1979, pp. 62-66 Summary of the Invention

[0011] Problems to be Solved by the Invention

[0012] According to the studies of the inventors of the present invention, it has been found that the conductive elastomer according to Patent Document 1 has low hardness, but there are problems in achieving low compression set because a large amount of conductive filler is added thereto.

[0013] It has also been found that the conductive elastomer according to Patent Document 2 has problems in terms of compatibility with low hardness and low compression set because low hardness and low compression set are in a trade-off relationship.

[0014] An object of the present invention is to provide a conductive molded body having low compression set and low hardness.

[0015] Solution to the problem

[0016] One aspect of the present disclosure provides a molded body comprising

[0017] a polyurethane elastomer, and

[0018] a conductive filler contained in the polyurethane elastomer, wherein

[0019] the polyurethane elastomer has a matrix and domains dispersed in the matrix, the matrix has a first structure represented by the following formula (1),

[0020] the domains have a second structure different from the first structure,

[0021] the conductive filler is mainly distributed in the matrix,

[0022] the relationship between parameter A and parameter B is A < B, where parameter A represents the viscoelastic term of the domain measured in the viscoelastic image by scanning probe microscopy on a cross-section of the molded body exposing the domain and the matrix, and parameter B represents the viscoelastic term of the matrix measured in the viscoelastic image by scanning probe microscopy on a cross-section of the molded body exposing the domain and the matrix,

[0023] the content of the conductive filler in the molded body is 0.02 to 5.0% by mass,

[0024] the volume resistivity of the molded body is 1.0×10 9 Ω·cm or less, and

[0025] the Young's modulus of the molded body is 0.5 to 4.0 MPa:

[0026] [Chemical formula 1]

[0027]

[0028] wherein, in formula (1), R 1 represents a C3-12 alkylene group.

[0029] Advantageous effects of the invention

[0030] According to at least one aspect of the present disclosure, a conductive molded body having low compression set and low hardness is provided. Brief description of the drawings

[0031] Figure 1 is a schematic view showing a method for manufacturing a molded body according to the present disclosure. Detailed description

[0032] ​In the present disclosure, unless otherwise specified, the expression "XX or more and YY or less" or "XX to YY" indicating a numerical range means a numerical range including the lower limit and the upper limit as endpoints. Further, when describing a numerical range in a stepwise manner, the upper limit and the lower limit of each numerical range can be arbitrarily combined. In the present disclosure, for example, a description such as "at least one selected from the group consisting of XX, YY, and ZZ" means one of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, and a combination of XX, YY, and ZZ.

[0033] Embodiments of the present disclosure will be described below. The embodiments described below are merely illustrative, and the present disclosure is not limited to these embodiments unless otherwise specified.

[0034] There are some problems in obtaining a conductive molded body having low compression set and low hardness. The first problem arises in the research on a base material for reducing compression set while maintaining low hardness. Low hardness and low compression set are basically a trade-off relationship, and it is difficult to make low hardness and low compression set compatible with each other.

[0035] The second problem arises in achieving both low hardness and low compression set even when a conductive filler to be added is added to the base material. In order to impart conductivity, a conductive filler must be added to the base material. However, adding the conductive filler increases hardness and compression set. Considering this influence, it is necessary to achieve both low hardness and low compression set.

[0036] To solve such problems, the inventors of the present invention conducted further research. As a result, it was found that for the first problem, it is effective to use a polyurethane elastomer having a matrix-domain structure introduced therein as the base material, the matrix-domain structure having a matrix and domains, the matrix having a structure with low compression set (capable of increasing the deformation recovery rate), and each domain having a structure contributing to suppressing an increase in hardness.

[0037] Further, for the second problem, it was found that in order to cause the manifestation of conductivity by adding as small an amount of the conductive filler as possible, it is effective to mainly distribute the conductive filler in the matrix of the above-described matrix-domain structure. That is, it was found that the conductive filler preferentially forms a conductive path in the matrix, whereby a small amount of the conductive filler can cause the manifestation of conductivity, and thus the increase in hardness and compression set caused by the addition of the conductive filler can be minimized.

[0038] Based on the above research findings, in achieving low hardness, low compression set (rapid deformation recovery), and electrical conductivity, it is effective to distribute a small amount of conductive filler mainly in the matrix of a polyurethane elastomer substrate including a matrix and domains, the matrix having a structure that increases the deformation recovery rate; and the domains having a structure that helps suppress the increase in hardness.

[0039] The shaped body according to the present disclosure includes a polyurethane elastomer and a conductive filler contained in the polyurethane elastomer.

[0040] Referring to the preferred embodiments, the polyurethane elastomer, the conductive filler, and the shaped body will be described in detail hereinafter.

[0041] <Polyurethane elastomer>

[0042] The polyurethane elastomer has a matrix including a first structure (polycarbonate structure) represented by the following formula (1). The polyurethane obtained by the reaction of a polyol (polycarbonate polyol) having the first structure with a polyisocyanate has strong intermolecular forces between carbonate groups. Thereby, mechanical properties such as low compression set are exhibited. However, the strong intermolecular forces of the polyurethane result in an increase in hardness, and thus the polyurethane is not suitable for use in soft polyurethane elastomers.

[0043] [Chemical formula 2]

[0044]

[0045] (Formula (1), R 1 represents a C3-12 alkylene group.)

[0046] Meanwhile, generally, a soft polyurethane elastomer having a low elastic modulus has weak intermolecular forces, and thus, for this reason, the hardness can be suppressed to an extremely low level. However, the weak intermolecular forces of the polyurethane elastomer result in an increase in compression set.

[0047] The polyurethane elastomer according to the present disclosure has a matrix and domains dispersed in the matrix, the matrix having the first structure represented by formula (1). Each of the domains has a second structure different from the first structure. That is, in the polyurethane elastomer according to the present disclosure, the segments formed by the first structure and the segments formed by the second structure are phase-separated from each other. Due to having different structures, the two types of segments exist almost immiscibly with each other, forming a matrix-domain structure.

[0048] Such a distinct phase separation prevents the segments formed by the second structure from being included in the matrix. Thus, in the polyurethane elastomer according to the present disclosure, the matrix achieves low compression set due to the first structure represented by Formula (1). The matrix has at least one, preferably a plurality of, polycarbonate structures represented by Formula (1). When the matrix has a plurality of polycarbonate structures represented by Formula (1), these polycarbonate structures may each be a repeating structural unit.

[0049] When the polyurethane elastomer forms a matrix - domain structure, at least a part of the outer surface of the molded body may be formed by the matrix. For example, the entire outer surface of the molded body may be formed by the matrix.

[0050] The domains each have a second structure different from the first structure, and the elastic modulus of the domains is designed to be lower than that of the matrix. With such a configuration, the polyurethane elastomer can achieve low compression set while maintaining low hardness.

[0051] That is, in the polyurethane elastomer, the matrix is configured to function to achieve low compression set, and the domains are configured to function to achieve low hardness. As described above, the matrix and the domains are configured to function differently from each other, whereby low compression set and low hardness can be achieved at a higher level in the molded body according to the present disclosure.

[0052] The first structure of the matrix in the molded body having the polycarbonate structure represented by Formula (1) will be described. R in Formula (1) 1 represents a C3 - 12 alkylene group. R 1 preferably represents a C3 - 9 alkylene group, more preferably represents a C3 - 6 alkylene group. R 1 is also preferably a C6 - 9 alkylene group.

[0053] By making R 1 a C3 - 12 alkylene group, it is easy to ensure low compatibility with the segments formed by the second structure, and the matrix and the domains can be clearly phase - separated. By making R 1 a C3 - 9 alkylene group, the intermolecular force between carbonate groups can be moderately inhibited, and excellent friction characteristics, as well as both high wear resistance and low hardness, can be achieved, which is more preferable.

[0054] Examples of R 1 include: -(CH 2 ) m -(m = 3 - 12 (preferably 3 - 9, more preferably 3 - 6 or 6 - 9)); -CH 2 C(CH 3 ) 2 CH 2 -; -CH 2 CH(CH 3 )CH 2-; and -(CH 2 ) 2 CH(CH 3 )(CH 2 ) 2 -. In the polyurethane elastomer, R 1 can all be the same, or different Rs can be combined 1 .

[0055] As the repeating unit in the polyurethane elastomer, the number average molecular weight (Mn) of the polycarbonate structure represented by the formula (1) is preferably 500 or more and 10,000 or less. This number average molecular weight is based on the raw material polycarbonate polyol. The number average molecular weight is more preferably 700 or more and 8,000 or less. When the number average molecular weight is 500 or more, the low compatibility with the polyurethane segment having the second structure is ensured, and the phase separation between the matrix and the domain is clearer. Further, when the number average molecular weight is set to 10,000 or less, an increase in the viscosity of the polycarbonate polyol as the raw material can be suppressed.

[0056] The number average molecular weight of the aforementioned polycarbonate structure and the number average molecular weight of polyols and the like described later are all converted according to the polystyrene standard molecular weight or calculated using the hydroxyl value (mgKOH / g) and the valence number.

[0057] The number average molecular weight converted according to the polystyrene molecular weight can be measured using high performance liquid chromatography. The measurement can be carried out using the high-speed GPC device "HLC-8220GPC" manufactured by Tosoh Corporation, in which two Shodex GPC LF-804 (molecular weight exclusion limit: 2×10 6 , separation range: 300~2×10 6 ) columns are connected in series.

[0058] When using the hydroxyl value and the valence number, the number average molecular weight can be calculated by the following formula. For example, the number average molecular weight of a polyol with a hydroxyl value of 56.1 mgKOH / g and a valence number of 2 can be calculated as 2000.

[0059] Number average molecular weight = 56.1×1000×valence number / hydroxyl value

[0060] The second structure different from the first structure represented by the formula (1) in the shaped body will be described. The elastic modulus of the domain containing the polyurethane having the second structure is designed to be lower than the elastic modulus of the matrix. There is no particular limitation on the second structure as long as the relationship between the above elastic moduli is satisfied and a domain separated from the matrix having the first structure can be formed.

[0061] Examples of such a second structure are polyether structures represented by the following formula (2). R 2represents a C3-6 alkylene group. R 2 is preferably a C3-5 alkylene group having a branched structure, more preferably a C3-4 alkylene group having a branched structure.

[0062] By making R 2 a C3-6 alkylene group, the low compatibility with the polyurethane chain segment having a polycarbonate structure represented by the formula (1) is ensured, and the matrix and the domain can be more clearly phase-separated. When R 2 is a C3-5 alkylene group having a branched structure, the intermolecular force between ether groups is extremely suppressed, and it is easier to achieve low hardness.

[0063] Each domain preferably has at least one, more preferably a plurality of polyether structures represented by the formula (2). When each domain has a plurality of polyether structures represented by the formula (2), these polyether structures can each be a repeating structural unit.

[0064] R 2 Examples include: -(CH 2 ) m -(m = 3-6 (preferably 3-5, more preferably 3-4)); -CH 2 CH(CH 3 )-; -CH 2 C(CH 3 ) 2 CH 2 -; -CH 2 CH(CH 3 )CH 2 -; -(CH 2 ) 2 CH(CH 3 )CH 2 -; and -(CH 2 ) 2 CH(CH 3 )(CH 2 ) 2 -. In the polyurethane elastomer, R 2 can all be the same, or different R 2 can be combined.

[0065] [Chemical formula 3]

[0066]

[0067] (In the formula (2), R 2 represents a C3-6 alkylene group.)

[0068] As a repeating unit in the polyurethane elastomer, the number average molecular weight (Mn) of the polyether structure represented by the formula (2) is preferably 1000 or more and 50000 or less. This number average molecular weight is based on the raw material polyether polyol. The number average molecular weight is more preferably 1200 or more and 30000 or less.

[0069] By making the number average molecular weight 1000 or more, the low compatibility with the polyurethane chain segment having the polycarbonate structure represented by the formula (1) is ensured, and the phase separation between the matrix and the domain can be made clearer. By making the number average molecular weight 50000 or less, the segment having the polyether structure easily forms a domain, and the phase separation structure can be further stabilized.

[0070] In the polyurethane elastomer, as described above, the elastic modulus of the domain containing the polyurethane having the second structure is designed to be lower than that of the matrix. Specifically, the parameter A representing the viscoelastic term of the domain and the parameter B representing the viscoelastic term of the matrix are set; these viscoelastic terms are measured in the viscoelastic image of the cross section exposed by the domain and the matrix; and the viscoelastic image is obtained by a scanning probe microscope. At this time, the parameters A and B satisfy A < B.

[0071] The difference in relative elastic modulus between the matrix and the domain in the polyurethane elastomer can be measured by thinning the polyurethane elastomer into a sheet and observing it with a scanning probe microscope (SPM / AFM). As the scanning probe microscope, “S-Image” (trade name) manufactured by Hitachi High-Tech Corporation can be used.

[0072] Examples of the means for thinning include a sharp razor, a microtome, and a focused ion beam method (FIB). In the present disclosure, a microtome is used. A total of 3 sections are prepared, a 50 μm square observation area is arbitrarily selected, and the viscoelastic image is observed in a total of 3 observation areas.

[0073] The viscoelastic dynamic force mode (VE-DFM) will be used as the measurement mode of the viscoelastic image using SPM. As the cantilever, a silicon microcantilever for DFM (“SI-DF3” (trade name), manufactured by Hitachi High-Tech Corporation, spring constant = 1.9 N / m) is used. In addition, the scanning frequency is set to 0.5 Hz.

[0074] VE-DFM (Viscoelastic DFM) is a mode of measuring the viscoelastic distribution while controlling the distance between the probe and the sample to keep the vibration amplitude of the cantilever in the resonance state constant and obtaining an image of the surface profile. In VE-DFM, when the sample vibrates slightly in the Z direction to apply a periodic force, the viscoelastic distribution is imaged based on the deflection amplitude of the cantilever. When the sample is hard, due to the smaller deformation of the sample, the amplitude of the cantilever increases; and when the sample is soft, the deformation vibration of the sample is induced and the amplitude of the cantilever decreases.

[0075] The obtained amplitude is converted into mV as displacement, which is a parameter representing the viscoelastic term. Therefore, parameters A and B are indicators showing the hardness relationship between the domains and the matrix existing in one of the samples. It should be noted that in VF-DFM, the magnitude of the amplitude of the cantilever is output as voltage, so the units of parameters A and B are mV. In addition, the larger the value of the parameter, the higher the elasticity is shown.

[0076] After obtaining the viscoelastic image, 10 points of 1 parameter representing the viscoelastic term of the matrix and 10 points of 1 parameter representing the viscoelastic term of the domain are obtained from each observation region, and the arithmetic means of these parameters of the matrix and the domain are used as parameter A representing the viscoelastic term of the domain and parameter B representing the viscoelastic term of the domain. The measurement process will be described below.

[0077] The ratio of parameter A to parameter B (A / B) is preferably 0.65 or less. This value is more preferably 0.05 - 0.50, further preferably 0.05 - 0.40, still more preferably 0.10 - 0.30, and particularly preferably 0.12 - 0.20. The smaller A / B is, the greater the viscoelastic difference between the matrix and the domain is, so it is easier to balance the achievement of hardness and the recovery of deformation.

[0078] Parameters A and B can be adjusted by, for example, the elastic moduli of the domains and the matrix. The elastic modulus of the matrix can be increased, for example, by using a trimer compound or a polymer compound of polyisocyanate as a raw material for forming the matrix to increase the crosslinking density of the matrix. The elastic modulus of the domain is decreased, for example, by increasing the molecular weight of the polyether polyol as a raw material for forming the domain to reduce the crosslinking density of the domain.

[0079] The area ratio of the matrix to the domain (matrix / domain) observed in a 50 μm × 50 μm observation region in the cross-section where the domain and the matrix are exposed is preferably 50 / 50 - 85 / 15. The ratio is more preferably 55 / 45 - 80 / 20, and further preferably 60 / 40 - 75 / 25. If the area ratio of the matrix is 50% or more, the phase separation morphology tends to be stable, which easily leads to the more stable formation of the matrix and the domain. When the area ratio of the matrix is 85% or less, it tends to be easy to balance the achievement of low hardness and conductivity.

[0080] The above area ratio can be controlled by the amounts of the materials of the domains and the matrix to be used.

[0081] The arithmetic mean (average diameter) of the circular equivalent diameters of the domains observed in a cross-section exposing the domains and the matrix is preferably 0.2 to 30.0 μm. This arithmetic mean is more preferably 0.5 to 20.0 μm, further preferably 1.0 to 7.0 μm, and still more preferably 1.5 to 5.0 μm. Making the circular equivalent diameter 0.2 μm or more makes it easier to achieve low hardness; and making the circular equivalent diameter 30.0 μm or less further stabilizes the phase separation morphology.

[0082] The circular equivalent diameter of the domains can be controlled, for example, by changing the isocyanate index in the following steps for obtaining the first urethane prepolymer. Specifically, the circular equivalent diameter is easily increased by decreasing the isocyanate index and easily decreased by increasing the isocyanate index. Further, the circular equivalent diameter of the domains can also be controlled by the materials and molecular weights of the domains to be used, and the shear force applied when mixing the materials of the matrix.

[0083] The area ratio of the matrix / domains and the average diameter of the domains are calculated based on a cross-sectional image of the urethane-based elastomer obtained using a scanning probe microscope. This will be specifically described below.

[0084] The chemical structures of the components contained in the matrix and the domains can be analyzed using, for example, spectrometers such as AFM infrared spectrometers, microscopic infrared spectrometers, and microscopic Raman spectrometers, or mass spectrometers.

[0085] Further, when observing three observation regions of 50 μm square placed on the cross-section of the molded body, the ratio of the number of domains having a circularity of 0.60 to 0.95 to the total number of domains is preferably 70 number % or more. This ratio is more preferably 80 to 99 number %, and further preferably 85 to 95 number %.

[0086] When the domains having a circularity within the above range recover from deformation, anisotropy in the direction of the shape recovery of the domains is less likely to occur. By making the number (ratio) of domains having a circularity within the above range large, anisotropy is also less likely to occur when recovering from deformation. In other words, the molded body is configured in a more isotropic manner for the recovery from the deformation of the molded body, and as a result, wrinkles, distortions, etc. due to anisotropy in the recovery from the deformation are less likely to occur after the recovery from the deformation.

[0087] The number ratio can be adjusted, for example, by the rate of injecting the material into the mold. As the injection rate decreases, the shear force applied to the material also decreases, and the material can be heat-set while maintaining a high circularity.

[0088] <Conductive filler>

[0089] For the purpose of imparting conductivity, a conductive filler is added. However, generally, adding a conductive filler to an elastomeric material results in a significantly increased hardness and an increased compression set. In contrast, in the shaped body according to the present disclosure, the conductive filler is mainly distributed in the matrix to form a conductive path, and the inclusion of the conductive filler in the domain is prevented as much as possible.

[0090] In the shaped body according to the present disclosure, compared with a conventional homogeneous material without a matrix-domain structure, this allows a smaller amount of conductive filler to impart conductivity. Therefore, low compression set and low hardness can be achieved while imparting conductivity after such addition of the conductive filler.

[0091] The conductive filler can be used without particular limitation as long as it exhibits conductivity. Examples of the conductive filler include: solid carbons such as carbon black, graphite, carbon nanotubes, fullerenes, graphene, and carbon nanowalls; powders of metals such as silver, copper, aluminum, nickel, and iron; conductive metal oxides such as conductive tin oxide and conductive titanium oxide; and inorganic ionic substances such as lithium perchlorate, sodium perchlorate, and calcium perchlorate. One of them can be used alone, or two or more of them can be used in combination.

[0092] Among them, from the viewpoint that conductivity can be imparted by a small amount of addition, solid carbons such as carbon black, graphite, carbon nanotubes, fullerenes, graphene, and carbon nanowalls are preferred. More preferably, conductive carbon blacks such as furnace black, thermal black, acetylene black, Ketjen black, PAN (polyacrylonitrile)-based carbon, and pitch-based carbon are preferred because the resistance can be easily adjusted to a desired range by appropriately selecting the particle size, structure, etc. From the viewpoint that conductivity can be imparted by an extremely small amount of addition, carbon nanotubes are preferred.

[0093] As the conductive carbon black used herein, DENKABLACK manufactured by Denka Company Limited, Ketjenblack series manufactured by Lion Corporation, NIPex 160IQ manufactured by Orion Engineered Carbons GmbH, etc. are preferred. Examples of the Ketjenblack series used herein include Ketjenblack EC600JD, Ketjenblack EC300J, Carbon ECP, and Carbon ECP600JD.

[0094] The percolation theory can explain the mechanism of conductivity caused by conductive fillers, and there is a tendency as follows: when the filling rate of the conductive filler is low, the conductivity does not change; but when its filling rate exceeds a certain critical filling rate, the conductive fillers form conductive paths arranged at a certain interval or less, resulting in a sharp increase in conductivity (a decrease in volume resistivity), and then the conductivity reaches a constant value.

[0095] In the molded body according to the present disclosure, the conductive fillers are mainly distributed in the matrix. Specifically, the total area of the conductive fillers in each 30 μm × 30 μm observation region observed in a cross-section composed of an exposed domain and a matrix is defined as the content C. The total area of the conductive fillers contained in the matrix in the 30 μm × 30 μm observation region is defined as the content D. The ratio D / C of the content D to the content C is D / C ≥ 0.70.

[0096] Preferably, D / C ≥ 0.80, and more preferably, D / C ≥ 0.90. There is no particular limitation on the upper limit, but preferably, D / C ≤ 1.00. When the relationship between the contents C and D of the conductive fillers is D / C ≥ 0.70, the influence of the functional hindrance of low hardening caused by the inclusion of conductive fillers in the domain is reduced, and it becomes easier to balance the achievement of low hardness and conductivity.

[0097] D / C can be increased, for example, by improving the dispersibility of the conductive fillers and the material of the matrix to be used. Additionally, for example, D / C can be decreased, for example, by improving the dispersibility of the conductive fillers and the material of the domain to be used. Specifically, D / C can be increased by reducing the amount of hydrophilic functional groups on the surface of the conductive fillers. For example, D / C can be easily increased by reducing the carboxyl groups of carbon black to make the hydrophobicity of the surface of the conductive fillers close to the hydrophobicity of the matrix. D / C can be decreased by increasing the amount of hydrophilic functional groups on the surface of the conductive fillers.

[0098] The measurement methods of the contents C and D of the conductive fillers will be described below.

[0099] Based on the mass of the molded body, the content of the conductive fillers in the molded body is 0.02 to 5.0% by mass. When the content of the conductive fillers is 0.02% by mass or more, conductivity can be imparted to the molded body. When the content of the conductive fillers is 5.0% by mass or less, conductivity, low hardness, and low compression set can all be achieved.

[0100] The content of the conductive fillers is preferably 0.05 to 4.5% by mass, and more preferably 0.1 to 4.0% by mass.

[0101] Specifically, when the conductive filler has a specific surface area of less than 500 m 2When the conductive filler is carbon black of 1.0 to 4.5 mass%, preferably 1.5 to 4.0 mass%, per g (e.g., DENKA BLACK manufactured by Denka Company Limited). When the conductive filler is carbon black having a specific surface area of 500 m 2 / g or more (e.g., Ketjenblack series manufactured by Lion Corporation), its content is preferably 0.2 to 4.0 mass%, and more preferably 0.5 to 3.5 mass%. When the conductive filler is a tubular carbon fiber (carbon nanotube) or needle-shaped carbon fiber (carbon nanofiber) having a specific surface area of 500 m 2 / g or more (e.g., single-walled carbon nanotube (TUBALL (registered trademark)) manufactured by OCSiAl), its content is preferably 0.05 to 3.0 mass%, and more preferably 0.1 to 2.5 mass%.

[0102] When the conductive filler is solid carbon, its content can be calculated using a thermogravimetric analysis / differential thermal analyzer (TG-DTA).

[0103] Specifically, the measurement is performed according to the following steps.

[0104] Using TG-DTA, the temperature of the sample placed in a predetermined container is raised to 600 °C at a heating rate of 10 °C / minute in a nitrogen atmosphere and held for 10 minutes, and then cooled to 400 °C at a cooling rate of 10 °C / minute, and the weight loss W1 (%) from the start of the measurement is measured. Then, the temperature of the sample is raised again to 800 °C at a heating rate of 10 °C / minute in an air atmosphere, and the weight loss W2 (%) from the start of the measurement is measured. The content of the conductive filler (solid carbon) can be calculated as the difference between W2 and W1 (W2 - W1 (%)).

[0105] <Formed body>

[0106] The volume resistivity of the formed body at 23 °C is 1.0×10 9 Ω·cm or less. A volume resistivity of 1.0×10 9 Ω·cm or less means that the formed body has excellent conductivity.

[0107] The volume resistivity is preferably 1.0×10 8 Ω·cm or less, and more preferably 1.0×10 6 Ω·cm or less. The lower the volume resistivity, the more preferable. There is no particular limitation on the lower limit, but it is preferably 1.0×10 1 Ω·cm or more.

[0108] The volume resistivity is preferably 1.0×10 1 ~1.0×109 Ω·cm, 1.0×10 1 ~1.0×10 8 Ω·cm or 1.0×10 1 ~1.0×10 6 Ω·cm.

[0109] The volume resistivity can be measured by placing the formed body in a sample holder SH2-Z (manufactured by TOYO Corporation) and applying a DC voltage of 1 to 50 V, and using a digital ultra-high resistance / microammeter R8340A (manufactured by ADVANTEST CORPORATION).

[0110] The volume resistivity can be controlled by the amount of conductive filler, the material of the domain to be used, and the amount of the matrix material (matrix / domain area ratio).

[0111] The Young's modulus of the formed body at 23°C is 0.5 to 4.0 MPa. The Young's modulus within this range promotes the achievement of low hardness and allows for soft deformation corresponding to external forces such as compression and tension.

[0112] The Young's modulus is preferably 0.8 to 3.5 MPa, and more preferably 1.0 to 2.5 MPa. The Young's modulus can be measured by performing a tensile test using a universal tensile testing machine (manufactured by Orientec Corporation, product name: TENSILON RTF-1250).

[0113] The Young's modulus can be controlled by the amount of conductive filler, the material of the domain to be used, and the amount of the matrix material (matrix / domain area ratio), chemical structure, and crosslink density.

[0114] In the temperature-loss tangent (tanδ) curve obtained by dynamic viscoelasticity measurement (DMA) of the formed body, preferably, there are two or more peaks derived from glass transitions observed in the temperature range of -80 to +20°C. More preferably, there are two or more peaks derived from glass transitions observed in the temperature range of -70 to 0°C. Further preferably, there are two or more peaks derived from glass transitions observed in the temperature range of -70°C to -10°C.

[0115] The peak positions within any of the above ranges indicate that the polyurethane segments having the first structure represented by formula (1) and the polyurethane segments having the second structure represented by formula (2) are more clearly separated from each other via the interface between the matrix and the domain.

[0116] The positions of the peaks derived from glass transitions can be controlled by the chemical structure and molecular weight of the material of the domain to be used and the matrix material.

[0117] In addition, in the temperature - tanδ curve obtained by DMA of the shaped body, preferably, at least one peak derived from the glass transition is observed in the temperature range of -50°C or lower (preferably -80°C to -50°C). At the same time, preferably, at least one peak is in the temperature range of -40°C or higher (preferably -40°C to 20°C). More preferably, at least one peak is in the temperature range of -60°C or lower (more preferably -70°C to -60°C), and at least one peak is in the temperature range of -35°C or higher (more preferably -35°C to -10°C).

[0118] Generally, a peak derived from the glass transition of the second structure represented by formula (2) is observed in the temperature range of -80°C to -50°C or lower. Further, a peak derived from the glass transition of the polyurethane segment having the first structure represented by formula (1) is observed in the temperature range of -40°C to +20°C or lower. Therefore, the peaks derived from the glass transition in the above two temperature ranges mean the following situation.

[0119] In the shaped body, the segments formed by the first structure and the segments formed by the second structure are separated from each other. The two types of segments exist almost immiscibly with each other to form a matrix - domain structure. Such distinct phase separation prevents the segments formed by the second structure from being included in the matrix. Thus, in the shaped body according to the present disclosure, although the shaped body has a low hardness, low compression set is achieved by the matrix.

[0120] There is no particular limitation on the shaped body according to the present disclosure, but it can be synthesized, for example, by a method including the following steps (i) to (iii):

[0121] Step (i): React a first urethane prepolymer having at least one (preferably at least two) isocyanate groups with a first polycarbonate polyol having at least two hydroxyl groups to obtain a second urethane prepolymer having at least two hydroxyl groups;

[0122] Step (ii): Mix the second urethane prepolymer, the conductive filler, and the second polycarbonate polyol (which may also be the remaining unreacted material of the first polycarbonate polyol) to obtain a dispersion formed by dispersing droplets containing at least a part of the second urethane prepolymer in the second polycarbonate polyol containing the conductive filler; and

[0123] Step (iii): Prepare a shaped - body - forming mixture containing the dispersion and a polyisocyanate having at least two isocyanate groups, and then react the second urethane prepolymer, the second polycarbonate polyol, and the polyisocyanate in the mixture to form a shaped body of a polyurethane elastomer.

[0124] A manufacturing method of the shaped body according to one aspect of the present disclosure will be described with reference to Figure 1 (the conductive filler is not shown). The manufacturing method of the shaped body according to the present disclosure is not limited to this embodiment.

[0125] In step (i), a first urethane prepolymer 51 having at least one (preferably at least two) isocyanate groups is mixed with a first polycarbonate polyol 52 having at least two hydroxyl groups. Next, in the presence of a curing catalyst, the isocyanate groups and hydroxyl groups in the obtained mixture are reacted to connect the two groups via urethane bonds, thereby obtaining a second urethane prepolymer 53 having at least two hydroxyl groups.

[0126] In Figure 1 , a polyether having two isocyanate groups is shown as an example of the first urethane prepolymer 51. An example of the first urethane prepolymer 51 is a urethane prepolymer having a second structure, and a preferred example thereof is a reaction product of a polyol and a polyisocyanate such as a polyether diol.

[0127] In step (ii), a dispersion is obtained by dispersing droplets containing at least a part of the second urethane prepolymer in a second polycarbonate polyol containing a conductive filler. Here, the second urethane prepolymer can be mixed with the second polycarbonate polyol newly added in this step. The remaining unreacted substances of the first polycarbonate polyol in step (i) can also be used as the second polycarbonate polyol.

[0128] The first urethane prepolymer 51 contained in the second urethane prepolymer 53 is immiscible with the second polycarbonate polyol 55, but forms droplets 54.

[0129] On the contrary, the first polycarbonate polyol 52 contained in the second urethane prepolymer 53 is miscible with the second polycarbonate polyol 55. Therefore, via the first polycarbonate polyol 52, the droplets 54 containing the first urethane prepolymer 51 constituting a part of the second urethane prepolymer 53 are uniformly and stably dispersed in the second polycarbonate polyol 55. As a result, a dispersion is obtained by dispersing the droplets 54 containing the first urethane prepolymer 51 (second structure) in the second polycarbonate polyol 55.

[0130] In order to disperse the conductive filler in the matrix, the conductive filler can be pre-dispersed in the second polycarbonate polyol 55 before step (ii). In step (ii), the conductive filler is preferably dispersed in the second polycarbonate polyol 55. In the second urethane prepolymer formed in step (i), an interface is formed by urethane bonds of the droplets 54 that will later become domains, and it is difficult for the conductive filler to enter into the droplets 54.

[0131] Optionally, between steps (ii) and (iii), a conductive filler can be added. The conductive filler is well dispersed in the matrix. Since the interface between the matrix and the domains is firmly formed via a chemical bond (urethane bond), even when the conductive filler is added and stirred after step (ii), a large amount of the conductive filler does not enter into the domains.

[0132] For illustration purposes, steps (i) and (ii) are described separately, but these steps can also be a series of continuous steps.

[0133] In step (ii), the second polycarbonate polyol 55 in which the droplets 54 are dispersed can be the remaining unreacted material of the first polycarbonate polyol used in step (i) that has not reacted with the first urethane prepolymer. That is, in step (i), an excess of the first polycarbonate polyol is used relative to the first urethane prepolymer, so that a dispersion can be obtained as described in step (ii) by dispersing the second urethane prepolymer 53 in the remaining first polycarbonate polyol (i.e., the second polycarbonate polyol 55).

[0134] Even when an excess of the first polycarbonate polyol is used, a polycarbonate polyol (second polycarbonate polyol) can be additionally added as a dispersion medium for the second urethane prepolymer. In this case, the chemical composition of the additional polycarbonate polyol can be the same as or different from the chemical composition of the first polycarbonate polyol used in step (i).

[0135] Conversely, when an equivalent amount of the first polycarbonate polyol reacts with the first urethane prepolymer in step (i) and all of the first polycarbonate polyol is consumed, a new polycarbonate polyol is used as the second polycarbonate polyol in step (ii) to prepare the dispersion. And in this case, the chemical composition of the polycarbonate polyol used as the second polycarbonate polyol can be the same as or different from the chemical composition of the first polycarbonate polyol.

[0136] Finally, in step (iii), a mixture for forming a shaped body is prepared, which contains the dispersion prepared in step (ii) and a polyisocyanate 56 having at least two isocyanate groups. Then, the terminal hydroxyl groups of the second urethane prepolymer 53, the hydroxyl groups of the second polycarbonate polyol 55, and the isocyanate groups of the polyisocyanate 56 in the mixture are reacted.

[0137] Accordingly, a network structure via urethane bonds is formed, and the mixture for forming a shaped body is cured to obtain a shaped body according to the present disclosure. The shaped body 33 obtained in this way has a matrix-domain structure, which is formed by dispersing domains 32 each having a structure derived from the first urethane prepolymer 51 (i.e., the second structure) in a matrix 31 of a polyurethane elastomer containing a polycarbonate structure (i.e., the first structure) derived from the first polycarbonate polyol 52 and the second polycarbonate polyol 55.

[0138] Furthermore, the shaped body 33 contains a conductive filler, and the conductive filler is mainly distributed in the matrix 31. The domains 32 are each mainly composed of the second structure, and the interior of the domain can be configured to substantially not have a crosslinked structure. In other words, the domains 32 can be configured to exist in a substantially liquid state in the matrix. This allows the domains to have a low elastic modulus in the shaped body 33 according to the present disclosure.

[0139] In addition, not only is the liquid portion of the domain enclosed in the matrix, but the domain and the matrix are chemically bonded via urethane bonds at the boundary between the domain and the matrix. Therefore, when the load applied to the shaped body 33 is removed, the recovery of the domain from deformation can be associated with the recovery of the matrix from deformation.

[0140] That is, the domains in a substantially liquid state, for example, substantially do not have a crosslinked structure inside. Therefore, it is difficult for the domains deformed due to the application of a load to the shaped body 33 to autonomously recover from the deformation. However, in the shaped body according to the present disclosure, the domain and the matrix are chemically bonded (urethane-bonded) at the boundary between the domain and the matrix, so that together with the recovery of the matrix from deformation, the domain can also recover from the deformation. Thus, even when a load is repeatedly applied to and removed from the shaped body 33, stable deformation (deformation amount) and stable recovery from deformation can be achieved.

[0141] The above steps (i) and (ii) are steps of stably dispersing a polyol having a second structure, which is originally of low compatibility and difficult to stably and uniformly disperse, in a polyol having a first structure. That is, the first urethane prepolymer 51 is reacted with the first polycarbonate polyol 52 to form the second urethane prepolymer 53.

[0142] This enables the acquisition of a dispersion formed by stably and uniformly dispersing segments of the polyol derived from the first urethane prepolymer 51 in the second polycarbonate polyol. This makes it easy to produce a molded body 33 formed by dispersing domains 32 having a high roundness, a small size in the micron order, and a relatively uniform size distribution in a matrix 31.

[0143] Examples of other methods of mixing materials with low compatibility with each other are methods of mixing and dispersing by high shear force. However, according to this method, a high shear force is applied to the polyol having the second structure, and as a result, the shape of the domain is deformed and the roundness is reduced, and the size of the domain may also be non-uniform. In addition, the dispersion state is unstable, and the aggregation of the domains progresses in a relatively short time.

[0144] Furthermore, the incompatibility between the polyol having the second structure and the polyol having the first structure cannot be ensured, and the phase separation between the matrix and the domain in the resulting polyurethane elastomer becomes unclear. Therefore, it is difficult to obtain a molded body according to the present disclosure that can provide a soft elastomer with excellent deformation recovery properties.

[0145] There is no particular limitation on the usage amounts of the polyol having the second structure and the polyol having the first structure, and it may be an amount that allows the droplets 54 to be dispersed in the second polycarbonate polyol 55 to form distinct domains. For example, the polyol having the second structure: the polyol having the first structure is preferably 15:85 to 50:50 by mass basis, more preferably 20:80 to 50:50.

[0146] The first urethane prepolymer has at least one isocyanate group and has a second structure; preferably, it has at least one isocyanate group and a polyether structure represented by the formula (2). The first urethane prepolymer can be obtained, for example, by the following steps:

[0147] Reacting a polyether polyol having at least two hydroxyl groups and having a structure represented by the formula (2) with a polyisocyanate having at least two isocyanate groups.

[0148] Examples of the polyether polyol include: polyether-based polyols containing an alkylene structure such as polypropylene glycol, polytetramethylene glycol, a copolymer of tetrahydrofuran and neopentyl glycol, a copolymer of tetrahydrofuran and 3-methyltetrahydrofuran, etc.; random or block copolymers of these polyalkylene glycols. One of them can be used alone, or two or more of them can be used in combination.

[0149] Among polyether polyols, amorphous polyether polyols are preferred from the viewpoint of achieving low compatibility and low hardness with the second polycarbonate polyol described below. More preferably, the polyether polyol contains at least one selected from polypropylene glycol, a copolymer of tetrahydrofuran and neopentyl glycol, and a copolymer of tetrahydrofuran and 3-methyltetrahydrofuran. Even more preferably, it contains at least polypropylene glycol.

[0150] The number average molecular weight of the polyol having the second structure is preferably 1000 or more and 50000 or less. More preferably, the number average molecular weight is 1200 or more and 30000 or less. When the number average molecular weight is 1000 or more, low compatibility with the polycarbonate polyol is ensured, and the phase separation between the matrix and the domain in the resulting urethane-based elastomer is clearer. When the number average molecular weight is 50000 or less, the polyurethane segments derived from the polyether polyol tend to easily form domains, and the phase separation morphology is more stable.

[0151] Examples of the polyisocyanate to react with the polyol having the second structure include: pentamethylene diisocyanate; hexamethylene diisocyanate; isophorone diisocyanate; 2,4-toluene diisocyanate; 2,6-toluene diisocyanate; xylylene diisocyanate; diphenylmethane diisocyanate; trimer compounds (isocyanurates) or polymer compounds of these polyisocyanates; urethane-form polyisocyanates; buuret-type isocyanates; and water-dispersed polyisocyanates. One of these polyisocyanates can be used alone, or two or more of them can be used in combination.

[0152] Among the above-exemplified polyisocyanates, bifunctional isocyanates (diisocyanates) having two isocyanate groups are preferred due to their high compatibility with the polyol having the second structure and the ease of adjusting physical properties such as viscosity. More preferably, the above polyisocyanate contains at least one selected from hexamethylene diisocyanate, isophorone diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate. Xylylene diisocyanate is even more preferred.

[0153] In the step of reacting the polyol having the second structure with the polyisocyanate to obtain the first urethane prepolymer, the isocyanate index is preferably 0.05 to 8.0. The isocyanate index is more preferably 0.1 to 5.0. An isocyanate index within this range can result in a reduction of the components derived from the first urethane prepolymer that are not in the network structure and remain, and suppress the exudation of liquid substances from the polyurethane elastomer.

[0154] The isocyanate index represents the ratio ([NCO] / [OH]) of the number of moles of isocyanate groups in the isocyanate compound to the number of moles of hydroxyl groups in the polyol compound.

[0155] The first urethane prepolymer obtained by the reaction of a polyol having a second structure with a polyisocyanate has a structure connected via urethane bonds formed by the reaction of hydroxyl groups with isocyanate groups. The number-average molecular weight of the first urethane prepolymer is preferably 1000 or more and 100000 or less. More preferably, the number-average molecular weight is 1200 or more and 50000 or less.

[0156] The first polycarbonate polyol is a polycarbonate polyol having at least two hydroxyl groups and having a structure represented by formula (1); and is preferably a polycarbonate diol having a structure represented by formula (1). Examples of the first polycarbonate polyol include the reaction product of a polyol and phosgene, and the ring-opening polymer of a cyclic carbonate (such as an alkylene carbonate).

[0157] Examples of polyols used herein include propylene glycol, dipropylene glycol, trimethylene glycol, 1,4-tetramethylene glycol, 1,3-tetramethylene glycol, 2-methyl-1,3-trimethylene glycol, 1,5-pentamethylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, 3-methyl-1,5-pentamethylene glycol, 2,4-diethyl-1,5-pentamethylene glycol, glycerol, trimethylolpropane, trimethylolethane, cyclohexanediols (such as 1,4-cyclohexanediol), and sugar alcohols (such as xylitol and sorbitol).

[0158] Examples of alkylene carbonates used herein include trimethylene carbonate, tetramethylene carbonate, and hexamethylene carbonate.

[0159] The number-average molecular weight of the first polycarbonate polyol is preferably 500 or more and 10000 or less, and more preferably 700 or more and 8000 or less. When the number-average molecular weight is 500 or more, the low compatibility with the polyurethane segment having a polyether structure represented by formula (2) is ensured, and the phase separation between the matrix and the domain can be more distinct. When the number-average molecular weight is 10000 or less, it is preferable to prevent the operational difficulty of increasing the viscosity of the polycarbonate polyol as a raw material.

[0160] Similar to the number-average molecular weight of the polyether polyol, the number-average molecular weight of the first polycarbonate polyol can be calculated using the hydroxyl value (mgKOH / g) and the valence.

[0161] As the polyisocyanate 56 having at least two isocyanate groups used in step (iii), the same polyisocyanates as any of the above-exemplified polyisocyanates can be used as the raw material of the first urethane prepolymer. One of these polyisocyanates can be used alone, or two or more of them can be used in combination.

[0162] As the polyisocyanate used in step (iii), among the above-exemplified polyisocyanates, from the viewpoint of improving the elastic modulus of the matrix, polyisocyanates having at least 3 isocyanate groups such as trimer compounds (isocyanurates) or polymer compounds of polyisocyanates, urethane-based polyisocyanates, and biuret-based polyisocyanates are preferred.

[0163] More preferably, at least one selected from the group consisting of: a trimer compound (isocyanurate) of pentamethylene diisocyanate, a trimer compound (isocyanurate) of hexamethylene diisocyanate, a polymer compound of diphenylmethane diisocyanate, and polymeric MDI can be used. The curing catalysts for urethane-based elastomers are roughly classified into urethanization catalysts (reaction acceleration catalysts) for promoting rubberization (resinification) and foaming, and isocyanuration catalysts (isocyanate trimerization catalysts). In the present disclosure, one of them can be used alone, or they can be used in combination.

[0164] Among the above, polymeric MDI is preferred. Here, polymeric MDI is a mixture of monomeric MDI and high molecular weight polyisocyanate, and is represented by the following formula (A). In formula (A), n is preferably 0 or more and 4 or less.

[0165] Commercially available polymeric MDI can be used, and examples thereof include the Millionate MR series (manufactured by Tosoh Corporation) including Millionate MR200 (trade name).

[0166] [Chemical formula 4]

[0167]

[0168] As the polyisocyanate 56 having at least two isocyanate groups, polyisocyanates having at least 3 isocyanate groups such as polymeric MDI and bifunctional isocyanates having two isocyanate groups are preferably used in combination. The aforementioned combined use allows control of the crosslink density, and thus is preferred from the viewpoint of achieving both low hardness and low compression set.

[0169] There is no particular limitation on the amount of the polyisocyanate having at least 3 isocyanate groups and the bifunctional isocyanate having two isocyanate groups. As the amount mixed in the dispersion in step (iii), the ratio of the bifunctional isocyanate to the polyisocyanate having at least 3 isocyanate groups is preferably from 3:1 to 1:10, and more preferably from 1:1 to 1:6. There is also no particular limitation on the amount of the polyisocyanate relative to 100 parts by mass of the dispersion in step (iii), and examples thereof include 1 to 10 parts by mass and 3 to 8 parts by mass.

[0170] Examples of the urethanization catalyst used herein include: tin-based urethanization catalysts such as dibutyltin dilaurate and stannous octoate; amine-based urethanization catalysts such as triethylenediamine, tetramethylguanidine, pentamethyldiethylenetriamine, diethylimidazole, tetramethylpropylenediamine, N,N,N'-trimethylaminoethyl ethanolamine, and 1,4-diazabicyclo[2.2.2]octane-2-methanol. One of them can be used alone, or they can be used in combination. Among these urethanization catalysts, from the viewpoint of particularly promoting the urethanization reaction, triethylenediamine and 1,4-diazabicyclo[2.2.2]octane-2-methanol are preferred.

[0171] Examples of the isocyanuration catalyst used herein include: metal oxides such as Li 2 O and (Bu 3 Sn) 2 O; hydride compounds such as NaBH 4 ; alkoxide compounds such as NaOCH 3 , KO-(t-Bu), and borate salts; amine compounds such as N(C 2 H 5 ) 3 , N(CH 3 ) 2 CH 2 C 2 H 5 and 1,4-ethylenepiperazine (DABCO); basic carboxylic acid ester salts such as HCOONa, Na 2 CO 3 , PhCOONa / DMF, CH 3 COOK, (CH 3 COO) 2 Ca, alkali metal soaps, and naphthenate salts; basic formate compounds; and quaternary ammonium salt compounds such as ((R) 3 -NR’OH)-OCOR”.

[0172] Examples of the combined catalysts (cocatalysts) that can be used as isocyanurating catalysts include amine / epoxide, amine / carboxylic acid, and amine / alkylene imide. One of these isocyanurating catalysts and combined catalysts can be used alone, or they can be mixed and used.

[0173] As a catalyst for urethane synthesis, N,N,N'-trimethylaminoethyl ethanolamine (hereinafter referred to as ETA), which acts as a urethanating catalyst alone and also acts as an isocyanurating catalyst, can be used.

[0174] In the method for producing a polyurethane elastomer, a chain extender (polyfunctional low molecular weight polyol) can be used as needed. Examples of the chain extender include diols having a number average molecular weight of 1000 or less.

[0175] Examples of the diols used herein include ethylene glycol (EG), diethylene glycol (DEG), propylene glycol (PG), dipropylene glycol (DPG), 1,4-butanediol (1,4-BD), 1,6-hexanediol (1,6-HD), 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, benzenedimethanol (p-benzenedimethanol), and triethylene glycol.

[0176] Examples of the chain extenders other than diols used herein include polyols having three or more functional groups. Examples of the polyols having three or more functional groups include trimethylolpropane, glycerin, pentaerythritol, and sorbitol. One of them can be used alone, or they can be mixed and used.

[0177] As needed, additives such as conductive agents, pigments, plasticizers, waterproof agents, antioxidants, ultraviolet absorbers, and light stabilizers can also be used in combination.

[0178] The formed body can be used as an electrophotographic member such as a developing roller. The formed body can also be used for a pressure-sensitive conductive elastomer.

[0179] Examples

[0180] Examples according to the present invention will be described below, but the present invention is not limited to these examples.

[0181] <Materials Used>

[0182] The materials used in the examples and comparative examples are listed below.

[0183] [Polyol]

[0184] · A-1: Polyether diol (polypropylene glycol) [Product name: PREMINOL S4013F, R 2The number of carbon atoms = 3 (branched), Mn = 12,000, hydroxyl value: 9.4 mg KOH / g, manufactured by AGC Inc.

[0185] · A-2: Polyether diol (polypropylene glycol) [Product name: UNIOL D-4000, R 2 The number of carbon atoms = 3 (branched), Mn = 4,200, hydroxyl value: 40.4 mg KOH / g, manufactured by NOF CORPORATION

[0186] · A-3: Polyether diol (copolymer of tetrahydrofuran and 3-methyltetrahydrofuran) [Product name: PTG-L3000, R 2 The number of carbon atoms = 5 (branched) + 4 (linear), Mn = 2,900, hydroxyl value: 38.6 mg KOH / g, manufactured by Hodogaya Chemical Co., Ltd.

[0187] · A-4: Polyether diol (polytetramethylene glycol) [Product name: PTMG 4000, R 2 The number of carbon atoms = 4 (linear), Mn = 3,900, hydroxyl value: 29.1 mg KOH / g, manufactured by Mitsubishi Chemical Corporation

[0188] Regarding the number of carbon atoms of the polyether diol, for example, the notation of 5 (branched) + 4 (linear) means that R 2 has a C5 branched structure and a C4 linear structure.

[0189] · A-5: Polycarbonate diol [Product name: Kuraray Polyol C-2090, R 1 The number of carbon atoms = 6 (linear) + 6 (branched), Mn = 2,000, manufactured by KURARAY CO., LTD.

[0190] · A-6: Polycarbonate diol [Product name: Kuraray Polyol C-2065N, R 1 The number of carbon atoms = 9 (linear) + 9 (branched), Mn = 2,000, hydroxyl value: 56.4 mg KOH / g, manufactured by KURARAY CO., LTD.

[0191] · A-7: Polycarbonate diol [Product name: DURANOL T6002, R 1 The number of carbon atoms = 6 (linear), Mn = 1,900, hydroxyl value: 57.6 mg KOH / g, manufactured by Asahi Kasei Chemicals Corp.

[0192] · A-8: Polycarbonate diol [Product name: DURANOL G3452, R 1 has a carbon atom number = 3 + 4, Mn = 2.1×10 3 , hydroxyl value: 53.6 mg KOH / g, manufactured by Asahi Kasei Chemicals Corp.]

[0193] · A-9: Polyester diol [Product name: Kuraray Polyol P-2050, Mn = 1900, hydroxyl value: 58.1 mg KOH / g, manufactured by KURARAY CO., LTD.]

[0194] Regarding the carbon atom number of polycarbonate diol, for example, the description of 6 (linear) + 6 (branched) means that R 1 has a C6 linear structure and a C6 branched structure.

[0195] [Polyisocyanate]

[0196] · B-1: Benzene diisocyanate [Manufactured by Tokyo Chemical Industry Co., Ltd.]

[0197] · B-2: Polymerized MDI [Product name: Millionate MR-200, manufactured by Tosoh Corporation]

[0198] · B-3: Hexamethylene diisocyanate-based polyisocyanate [Product name: DURANOL TSE-100, manufactured by AsahiKasei Corporation]

[0199] [Curing catalyst]

[0200] · C-1: 1,4-Diazabicyclo[2.2.2]octane-2-methanol (Product name; RZETA) [Manufactured by TosohCorporation]

[0201] [Conductive filler]

[0202] · E-1: Carbon black [Product name: DENKABLACK granular product (manufactured by Denka Company Limited), average particle size: 35 nm, specific surface area: 69 m 2 / g]

[0203] · E-2: Carbon black [Product name: Ketjenblack EC300J (manufactured by Lion Specialty ChemicalsCo., Ltd.), average particle size: 39.5 nm, specific surface area: 800 m 2 / g]

[0204] ·E-3: Carbon black [Product name: Ketjenblack EC600JD (manufactured by Lion Specialty Chemicals Co., Ltd.), average particle size: 34.0 nm, specific surface area: 1270 m 2 / g]

[0205] ·E-4: Single-walled carbon nanotubes [Product name: TUBALL (registered trademark) (manufactured by OCSiAl)]

[0206] <Evaluation>

[0207] The evaluation methods in the examples and comparative examples are as follows.

[0208] [Evaluation 1: Confirmation and analysis of matrix and domain]

[0209] Ultra-thin sections (500 μm × 500 μm × 5 μm) were prepared from the formed body using a cryo-fracture system (trade name: EM FC6, manufactured by Leica Microsystems) and an ultramicrotome (trade name: EM UC6, manufactured by Leica Microsystems). Sections were prepared at a total of three positions: the center of the formed body and two positions sufficiently far from the center.

[0210] Mapping measurements were performed on the prepared sections using an infrared microscope / imaging system (trade name: Spectrum 400 (analyzer) and Spotlight 400 (scanning device), manufactured by PerkinElmer, Inc.) to generate mapping images. For the measurements, mapping measurements were performed using an ATR imaging attachment under the following conditions: pixel size: 1.56 μm; resolution: 16 cm -1 ; field of view: 300 μm × 300 μm; and scanning speed: 1.0 cm / s. On the mapping images, the magnitude of the integrated value of the infrared absorption spectrum for each pixel was imaged.

[0211] From each of the obtained mapping images, the presence of a matrix mapped as a continuous phase and the presence of a domain mapped as a discontinuous phase were confirmed. In addition, from the infrared absorption spectrum of the matrix in each mapping image, it was confirmed that the matrix has a structure corresponding to polycarbonate diol as a first structure. From the infrared absorption spectrum of the domain in each mapping image, it was confirmed that the domain has a second structure (for example, a structure corresponding to polypropylene glycol). That is, it was confirmed that the matrix has a carbonate structure represented by formula (1) and the domain has an ether structure represented by formula (2).

[0212] [Evaluation 2: Evaluation of parameters representing viscoelastic terms]

[0213] An ultrathin section was prepared in the same manner as in Evaluation 1.

[0214] The total number of sections prepared was three. Optionally, a 50-μm square observation area was selected, and viscoelastic images were observed in a total of three observation areas. In the total of three observation areas, a scanning probe microscope (trade name: S-Image, manufactured by SII NanoTechnology Inc.) was used to measure the viscoelastic images. The measurement mode for the viscoelastic images was set to VE-DFM. For the cantilever, "SI-DF3" (trade name, manufactured by Hitachi High-Tech Corporation, spring constant = 1.9 N / m) was used. In addition, the scanning frequency was set to 0.5 Hz.

[0215] From the obtained viscoelastic images, 10 parameters representing the viscoelastic terms of the matrix and 10 parameters representing the viscoelastic terms of the domain were obtained for each observation area, and the parameter A (mV) representing the viscoelastic terms of the domain and the parameter B (mV) representing the viscoelastic terms of the matrix were obtained from the arithmetic means of these parameters.

[0216] Note that in the viscoelastic images of the SPM, the exposed domain and matrix were confirmed in the cross section.

[0217] [Evaluation 3: Evaluation of the location and ratio (D / C) of the conductive filler]

[0218] (Evaluation using a 3D laser Raman microspectroscopic system)

[0219] Sections (500 μm × 500 μm × 5 μm) were prepared from the molded body using a cryo-fracture system (trade name: EM FC6, manufactured by Leica Microsystems) and an ultramicrotome (trade name: EM UC6, manufactured by Leica Microsystems).

[0220] At an arbitrary position in each section, a mapping image (hereinafter also simply referred to as "mapping image") based on the integrated intensity of the Raman peaks in a 30-μm × 30-μm square observation area was obtained under the following conditions using a 3D laser Raman microspectroscopic system (trade name: Nanofinder30, manufactured by Tokyo Instruments, Inc.): excitation wavelength 532 nm (Nd:YVO 4 laser light source); intensity 300 μW; 100× objective lens; pinhole diameter: 100 μm; and diffraction grating: 300 gr / mm.

[0221] The mapping image obtained here is:

[0222] Based on the 0-400 cm where peaks attributed to polycarbonate and polyether appear-1 The mapping image (first mapping image) of the integrated intensity of the peaks appearing in the region;

[0223] Based on the integrated intensity of the peaks appearing in the region of 1400 - 1800 cm where the peak attributed to the G band of carbon nanotubes appears; -1 The mapping image (second mapping image) of the integrated intensity of the peaks appearing in the region;

[0224] And the mapping image (third mapping image) of the integrated intensity of the peaks in the region of 1000 - 1800 cm where the peaks attributed to the G band and D band of carbon black appear. -1 In the first mapping image, the integrated intensity of the peaks attributed to polycarbonate is greater than the integrated intensity of the peaks attributed to polyether, thereby visualizing the presence of the matrix containing polycarbonate urethane and the presence of the domain containing polyether in the observation region.

[0225] From the second mapping image, the part of the carbon nanotubes can be distinguished from the region of the urethane - based elastomer. In addition, by comparing the first mapping image and the second mapping image, the part of the carbon nanotubes present in the matrix and the part of the carbon nanotubes present in the domain can be identified.

[0226] Furthermore, from the third mapping image, the part of the carbon black can be distinguished from the region of the urethane - based elastomer. In addition, by comparing the first mapping image and the third mapping image, the part of the carbon black present in the matrix and the part of the carbon black present in the domain can be identified.

[0227] Then, for the first mapping image, image - processing software (trade name: ImageProPlus, manufactured by MediaCybernetics, Inc.) is used to obtain an analysis - use binary image in which the part of the matrix containing polycarbonate urethane and the part of the domain containing polyether are binarized. In addition, for the second mapping image and the third mapping image, analysis - use binary images in which the part of the carbon black or carbon nanotubes and the part of the urethane - based elastomer are binarized are obtained in the same manner as the first mapping image. The threshold for binarization is determined from the brightness distribution of the mapping image and based on the Otsu algorithm described in Non - Patent Document 1.

[0228] Next, from the obtained binary image, the total area of the carbon black or carbon nanotubes (conductive filler) present in the observation region is obtained using the counting function of the image - processing software and defined as content C. Further, the total area of the carbon black or carbon nanotubes (conductive filler) present in the matrix is obtained and defined as content D. The ratio D / C of content D to content C is calculated.

[0229] Next, from the obtained binary image, use the counting function of the image - processing software to obtain the total area of carbon black or carbon nanotubes (conductive filler) present in the observation region, and define it as content C. Further, obtain the total area of carbon black or carbon nanotubes (conductive filler) present in the matrix, and define it as content D. Calculate the ratio D / C of content D to content C.

[0230] [Evaluation 4: Evaluation of volume resistivity]

[0231] The formed body with a thickness of 2 mm was cut into test pieces of 30 mm × 30 mm to measure the volume resistivity at 23°C. Specifically, the formed body was placed in a sample holder SH2-Z (manufactured by TOYO Corporation), an appropriate voltage was applied in the range of 2 to 50 V DC, and measurement was performed using a digital ultra-high resistance / microammeter R8340A (manufactured by ADVANTEST CORPORATION). The arithmetic mean of 3 samples was used. The appropriate voltage refers to the voltage value that allows the measurement of the current value using the above device.

[0232] [Evaluation 5: Evaluation of Young's modulus]

[0233] The formed body with a thickness of 2 mm was cut into test pieces of 5 mm × 30 mm to measure the Young's modulus at 23°C. Specifically, after setting the distance between chucks to 10 mm, a tensile test was performed on the test piece at a speed of 5 mm / min using a universal tensile testing machine (manufactured by Orientec Corporation, product name: Tensilon RTF-1250) to measure the Young's modulus (unit: MPa). The arithmetic mean of 3 samples was used.

[0234] [Evaluation 6: Evaluation of elastic deformation power (ηiT)]

[0235] As an evaluation index of compression set, the elastic deformation power (ηiT) at a temperature of 23°C was used. ηiT was measured under the following measurement conditions using a nanoindentation instrument (FISCHERSCOPE HM2000, manufactured by FISCHER INSTRUMENTS K.K.) and a Vickers indenter with a square pyramid shape having opposite faces intersecting at 136° as the indenter.

[0236] · Maximum indentation load: 10 mN

[0237] · Loading speed: 10 mN / 30 s

[0238] · Maximum load holding time: 60 s

[0239] · Unloading time: 5 s

[0240] ηiT was calculated from the obtained "load-displacement curve" using the following formula.

[0241] ηiT (%) = (elastic deformation work / total deformation work) × 100

[0242] The compression set was evaluated based on the obtained ηiT and the following criteria:

[0243] Evaluation criteria

[0244] Evaluation A: ηiT is 80% or more

[0245] Evaluation B: ηiT is 60% or more and less than 80%

[0246] Evaluation C: ηiT is less than 60%

[0247] [Evaluations 7 and 8: Evaluation of the arithmetic mean (average diameter) of the circular equivalent diameter of the domain and the area ratio]

[0248] Using image processing software (product name: ImageProPlus, manufactured by Media Cybernetics, Inc.), each of the three viscoelastic images obtained in Evaluation 2 is converted into a monochrome image with 256 gray levels, and then binarized to obtain a binarized image for analysis. The threshold for binarization is determined based on the luminance distribution of the monochrome image and the Otsu algorithm described in Non-Patent Document 1.

[0249] From each of the obtained binarized images, the cross-sectional area, number, and average cross-sectional area of the domain are obtained using the counting function of the image processing software. Note that among the domains determined as domains by the counting function, domains with a cross-sectional area of less than 0.05% in an arbitrary 50 μm square observation area are regarded as noise-originated domains and are deleted from the data. The area corresponding to the matrix is calculated by subtracting the cross-sectional area of the obtained domain from the total area of the observation area. Based on these areas, the area ratio (matrix / domain) is calculated.

[0250] The arithmetic mean (average diameter) of the circular equivalent diameter of the domain is calculated by the following formula:

[0251] Circular equivalent diameter of the domain = {(cross-sectional area of the domain) / (number) / (π)} 0.5

[0252] [Evaluation 9: tanδ peak temperature originating from glass transition]

[0253] Measurement is performed as follows using a viscoelasticity measuring device (product name: Physica MCR302, manufactured by Anton Paar GmbH): A test piece with a thickness of 2 mm and a width of 5 mm formed by a die cutter is set, and its viscoelasticity is measured in a torsional mode (twisting) with a length of 20 mm, at a heating rate of 2 °C / minute from -85 °C to 20 °C, and at a frequency of 1 Hz to obtain a temperature-tanδ curve.

[0254] (Evaluation 10: Measurement of the circularity and number of domains)

[0255] Based on the binarized images obtained in Evaluations 7 and 8, use the counting function of the above image processing software to calculate the circularity of the domains. In the same manner as in Evaluations 7 and 8, remove the domains caused by noise from the data. Among the domains in each observation region, count the number of domains with a circularity of 0.60 to 0.95 and calculate the ratio (%) with respect to the total number of domains in each observation region.

[0256] [Example 1]

[0257] [Preparation of urethane prepolymer UP1-1]

[0258] A polyol (first urethane prepolymer) having an isocyanate group at its end was synthesized by uniformly mixing 41.4 parts by mass of polyol A-1, 0.7 part by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100°C for 24 hours. In this mixture, 50.6 parts by mass of polyol A-5 was mixed and heated at a temperature of 100°C for 4 hours to produce urethane prepolymer UP1-1 (second urethane prepolymer) (Step (i)).

[0259] In the following examples and comparative examples, the amount of curing catalyst C-1 is in mass ppm based on the mass of all the materials used for the shaped body.

[0260] [Synthesis of shaped body No. 1]

[0261] By mixing 92.8 parts by mass of urethane prepolymer UP1-1 and 2.0 parts by mass of conductive filler E-1, and using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) to stir the mixture at a revolution speed of 1600 rpm until the mixture becomes homogeneous, urethane prepolymer UP1-2 containing the conductive filler was obtained (Step (ii)).

[0262] By mixing 94.8 parts by mass of UP1-2, 1.2 parts by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) to stir the mixture at a revolution speed of 1600 rpm for about 1 to 2 minutes until the mixture becomes homogeneous, a mixture for forming a shaped body was obtained.

[0263] Next, the mixture for forming the polyurethane elastomer was preheated to a temperature of 130°C, poured into a mold thinly coated with a mold release agent for manufacturing a sheet with a thickness of 2 mm, heated at a temperature of 130°C for 2 hours, and cured (step (iii)). Then, the cured product was demolded from the mold and post-cured at a temperature of 80°C for 3 days to obtain a formed body No. 1 in the shape of a sheet with a thickness of 2 mm.

[0264] [Example 2]

[0265] [Preparation of urethane prepolymer UP2-1]

[0266] A polyol having isocyanate groups at its ends was synthesized by uniformly mixing 32.0 parts by mass of polyol A-1, 0.5 part by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100°C for 24 hours. In this mixture, 59.4 parts by mass of polyol A-5 was mixed and heated at a temperature of 100°C for 4 hours to produce urethane prepolymer UP2-1.

[0267] [Synthesis of formed body No. 2]

[0268] A urethane prepolymer UP2-2 containing a conductive filler was obtained by mixing 91.9 parts by mass of urethane prepolymer UP2-1 and 3.1 parts by mass of conductive filler E-1, and stirring the mixture using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) at a revolution speed of 1600 rpm until the mixture became homogeneous. A mixture for forming a formed body was obtained by mixing 95.0 parts by mass of UP2-2, 2.1 parts by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and stirring the mixture using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) at a revolution speed of 1600 rpm for about 1 to 2 minutes until the mixture became homogeneous.

[0269] Next, except for using this mixture for forming a formed body, a formed body No. 2 was obtained in the same manner as in Example 1.

[0270] [Example 3]

[0271] [Preparation of urethane prepolymer UP3-1]

[0272] A polyol having isocyanate groups at its terminals was synthesized by uniformly mixing 22.6 parts by mass of polyol A-1, 0.4 part by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100 °C for 24 hours. In this mixture, 68.0 parts by mass of polyol A-5 was mixed, and the mixture was heated at a temperature of 100 °C for 4 hours to produce urethane prepolymer UP3-1.

[0273] <Synthesis of Formed Body No. 3>

[0274] A urethane prepolymer UP3-2 containing a conductive filler was obtained by mixing 91.0 parts by mass of urethane prepolymer UP3-1 and 3.6 parts by mass of conductive filler E-1, and stirring the mixture at a revolution speed of 1600 rpm using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) until the mixture became homogeneous. A mixture for forming a formed body was obtained by mixing 94.6 parts by mass of UP3-2, 3.0 parts by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and stirring the mixture at a revolution speed of 1600 rpm using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) for about 1 to 2 minutes until the mixture became homogeneous.

[0275] Next, except for using this mixture for forming a formed body, Formed Body No. 3 was obtained in the same manner as in Example 1.

[0276] [Example 4]

[0277] Formed Body No. 4 was obtained in the same manner as in Example 2, except that the addition amount of conductive filler E-1 was set to 4.7 parts by mass.

[0278] [Example 5]

[0279] Formed Body No. 5 was obtained in the same manner as in Example 2, except that 1.0 part by mass of conductive filler E-2 was used instead of conductive filler E-1.

[0280] [Example 6]

[0281] Urethane prepolymer UP6-1 was prepared in the same manner as in Example 2, except that polyol A-6 was used instead of polyol A-5. Further, except for using urethane prepolymer UP6-1, urethane prepolymer UP6-2 and Formed Body No. 6 were obtained in the same manner as in Example 2.

[0282] [Example 7]

[0283] A urethane prepolymer UP7-1 was prepared in the same manner as in Example 2, except that polyol A-7 was used instead of polyol A-5. Further, a urethane prepolymer UP7-2 and a molded body No.7 were obtained in the same manner as in Example 2, except that urethane prepolymer UP7-1 was used.

[0284] [Example 8]

[0285] A urethane prepolymer UP8-1 was prepared in the same manner as in Example 2, except that polyol A-8 was used instead of polyol A-5. Further, a urethane prepolymer UP8-2 and a molded body No.8 were obtained in the same manner as in Example 2, except that urethane prepolymer UP8-1 was used.

[0286] [Example 9]

[0287] A urethane prepolymer UP9-1 was prepared in the same manner as in Example 2, except that 41.5 parts by mass of polyol A-5 and 17.8 parts by mass of polyol A-9 were used instead of 59.4 parts by mass of polyol A-5. Further, a urethane prepolymer UP9-2 and a molded body No.9 were obtained in the same manner as in Example 2, except that urethane prepolymer UP9-1 was used.

[0288] [Example 10]

[0289] [Preparation of urethane prepolymer UP10-1]

[0290] A polyol having an isocyanate group at its end was synthesized by uniformly mixing 31.6 parts by mass of polyol A-2, 2.8 parts by mass of polyisocyanate B-1, and 500 ppm of a curing catalyst C-1, and heating the mixture at a temperature of 100°C for 24 hours. In this mixture, 58.8 parts by mass of polyol A-5 was mixed, and the mixture was heated at a temperature of 100°C for 4 hours to produce a urethane prepolymer UP10-1.

[0291] [Synthesis of molded body No.10]

[0292] A urethane prepolymer UP10-2 containing a conductive filler was obtained by mixing 93.2 parts by mass of urethane prepolymer UP10-1 and 3.1 parts by mass of a conductive filler E-1, and stirring the mixture at a revolution speed of 1600 rpm using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) until the mixture became homogeneous.

[0293] A mixture for forming a shaped body was obtained by mixing 96.3 parts by mass of UP10-2, 0.8 part by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and stirring the mixture at a revolution speed of 1600 rpm for about 1 to 2 minutes until the mixture became homogeneous using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.).

[0294] Next, except for using this mixture for forming a shaped body, a shaped body No. 10 was obtained in the same manner as in Example 1.

[0295] [Example 11]

[0296] [Preparation of urethane prepolymer UP11-1]

[0297] A polyol having an isocyanate group at its terminal was synthesized by uniformly mixing 31.4 parts by mass of polyol A-3, 4.1 parts by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100 °C for 4 hours. In this mixture, 58.3 parts by mass of polyol A-5 was mixed, and the mixture was heated at a temperature of 100 °C for 4 hours to produce urethane prepolymer UP11-1.

[0298] [Synthesis of shaped body No. 11]

[0299] A urethane prepolymer UP11-2 containing a conductive filler was obtained by mixing 93.8 parts by mass of urethane prepolymer UP11-1 and 3.1 parts by mass of conductive filler E-1, and stirring the mixture at a revolution speed of 1600 rpm until the mixture became homogeneous using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.).

[0300] A mixture for forming a shaped body was obtained by mixing 96.9 parts by mass of UP11-2, 0.2 part by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and stirring the mixture at a revolution speed of 1600 rpm for about 1 to 2 minutes until the mixture became homogeneous using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.).

[0301] Next, except for using this mixture for forming a shaped body, a shaped body No. 11 was obtained in the same manner as in Example 1.

[0302] [Example 12]

[0303] [Preparation of urethane prepolymer UP12-1]

[0304] A polyol having isocyanate groups at its terminals was synthesized by uniformly mixing 31.6 parts by mass of polyol A-4, 3.1 parts by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100 °C for 24 hours. In this mixture, 58.7 parts by mass of polyol A-5 was mixed, and the mixture was heated at a temperature of 100 °C for 4 hours, thereby producing urethane prepolymer UP12-1.

[0305] <Synthesis of Formed Body No. 12>

[0306] A urethane prepolymer containing a conductive filler, UP12-2, was obtained by mixing 93.4 parts by mass of urethane prepolymer UP12-1 and 3.1 parts by mass of conductive filler E-1, and stirring the mixture at a revolution speed of 1600 rpm using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) until the mixture became homogeneous.

[0307] A mixture for forming a formed body was obtained by mixing 96.5 parts by mass of UP12-2, 0.6 parts by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and stirring the mixture at a revolution speed of 1600 rpm using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) for about 1 to 2 minutes until the mixture became homogeneous.

[0308] Next, except for using this mixture for forming a formed body, Formed Body No. 12 was obtained in the same manner as in Example 1.

[0309] [Example 13]

[0310] <Preparation of Urethane Prepolymer UP13-1>

[0311] A polyol having isocyanate groups at its terminals was synthesized by uniformly mixing 35.7 parts by mass of polyol A-1, 0.6 parts by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100 °C for 24 hours. In this mixture, 53.6 parts by mass of polyol A-5 was mixed, and the mixture was heated at a temperature of 100 °C for 4 hours, thereby producing urethane prepolymer UP13-1.

[0312] <Synthesis of Formed Body No. 13>

[0313] The urethane prepolymer UP13-2 containing the conductive filler was obtained by mixing 89.9 parts by mass of the urethane prepolymer UP13-1 and 2.6 parts by mass of the conductive filler E-1, and stirring the mixture at a revolution speed of 1600 rpm using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) until the mixture became homogeneous.

[0314] The mixture for forming a shaped body was obtained by mixing 92.5 parts by mass of UP13-2, 4.1 parts by mass of the polyisocyanate B-1, and 6.0 parts by mass of the polyisocyanate B-3, and stirring the mixture at a revolution speed of 1600 rpm using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) for about 1 to 2 minutes until the mixture became homogeneous.

[0315] Next, except for using this mixture for forming a shaped body, a shaped body No. 13 was obtained in the same manner as in Example 1.

[0316] [Example 14]

[0317] Except for using 1.0 part by mass of the conductive filler E-2 instead of the conductive filler E-1, a shaped body No. 14 was obtained in the same manner as in Example 13.

[0318] [Example 15]

[0319] Except for using 1.0 part by mass of the conductive filler E-3 instead of the conductive filler E-1, a shaped body No. 15 was obtained in the same manner as in Example 13.

[0320] [Example 16]

[0321] Except for using 1.0 part by mass of the conductive filler E-4 instead of the conductive filler E-1, a shaped body No. 16 was obtained in the same manner as in Example 13.

[0322] [Example 17]

[0323] [Preparation of urethane prepolymer UP17-1]

[0324] A polyol having an isocyanate group at its end was synthesized by uniformly mixing 8.7 parts by mass of the polyol A-1, 0.3 parts by mass of the polyisocyanate B-1, and 500 ppm of the curing catalyst C-1, and heating the mixture at a temperature of 100 °C for 24 hours. In this mixture, 78.1 parts by mass of the polyol A-5 was mixed and heated at a temperature of 100 °C for 4 hours to produce the urethane prepolymer UP17-1.

[0325] <Synthesis of Formed Body No. 17>

[0326] By mixing 87.1 parts by mass of urethane prepolymer UP17-1 and 4.7 parts by mass of conductive filler E-1, and using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) to stir the mixture at a revolution speed of 1600 rpm until the mixture becomes homogeneous, a urethane prepolymer UP17-2 containing a conductive filler is obtained.

[0327] By mixing 91.8 parts by mass of UP17-2, 6.9 parts by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-3, and using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) to stir the mixture at a revolution speed of 1600 rpm for about 1 to 2 minutes until the mixture becomes homogeneous, a mixture for forming a formed body is obtained.

[0328] Next, except for using this mixture for forming a formed body, a formed body No. 17 is obtained in the same manner as in Example 1.

[0329] [Comparative Example 1]

[0330] <Preparation of Urethane Prepolymer UPC1-1>

[0331] By uniformly mixing 51.1 parts by mass of polyol A-1, 0.8 parts by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100°C for 24 hours, a polyol having an isocyanate group at its end is synthesized. In this mixture, 41.8 parts by mass of polyol A-5 is mixed, and the mixture is heated at a temperature of 100°C for 4 hours, thereby manufacturing urethane prepolymer UPC1-1.

[0332] <Synthesis of Formed Body No. C1>

[0333] By mixing 93.7 parts by mass of urethane prepolymer UPC1-1 and 2.0 parts by mass of conductive filler E-1, and using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) to stir the mixture at a revolution speed of 1600 rpm until the mixture becomes homogeneous, a urethane prepolymer UPC1-2 containing a conductive filler is obtained.

[0334] A mixture for forming a shaped body is obtained by mixing 95.7 parts by mass of UPC1-2, 0.3 part by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and stirring the mixture at a revolution speed of 1600 rpm for about 1 to 2 minutes until the mixture becomes homogeneous using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.).

[0335] Next, except for using this mixture for forming a shaped body, a shaped body No. C1 is obtained in the same manner as in Example 1.

[0336] [Comparative Example 2]

[0337] Except for setting the addition amount of the conductive filler E-1 to 6.4 parts by mass, a shaped body No. C2 is obtained in the same method as in Example 2.

[0338] [Comparative Example 3]

[0339] [Preparation of urethane prepolymer UPC3]

[0340] A polyol having an isocyanate group at its end is synthesized by uniformly mixing 32.0 parts by mass of polyol A-1, 3.1 parts by mass of conductive filler E-1, 0.5 part by mass of polyisocyanate B-1, and 500 ppm of curing catalyst C-1, and heating the mixture at a temperature of 100 °C for 24 hours. In this mixture, 59.4 parts by mass of polyol A-5 is mixed and heated at a temperature of 100 °C for 4 hours, thereby manufacturing a urethane prepolymer UPC3-1 containing a conductive filler.

[0341] [Synthesis of shaped body No. C3]

[0342] A mixture for forming a shaped body is obtained by mixing 95.0 parts by mass of UPC3, 2.1 parts by mass of polyisocyanate B-1, and 6.0 parts by mass of polyisocyanate B-2, and stirring the mixture at a revolution speed of 1600 rpm for about 1 to 2 minutes until the mixture becomes homogeneous using a rotary-revolution type vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.).

[0343] Next, except for using this mixture for forming a shaped body, a shaped body No. C3 is obtained in the same manner as in Example 1.

[0344] [Comparative Example 4]

[0345] Mix the following uniformly: 18.2 parts by mass of polyol A-2; 72.6 parts by mass of polyol A-4; 3.1 parts by mass of conductive filler E-1; and 500 ppm of curing catalyst C-1. A mixture for forming a shaped body is obtained by mixing 3.2 parts by mass of polyisocyanate B-1 and 6.0 parts by mass of polyisocyanate B-3 in this mixture and stirring the mixture at a revolution speed of 1600 rpm for about 1 to 2 minutes using a rotary planetary vacuum stirring and defoaming mixer (product name: V-mini300, manufactured by EME, Inc.) until the mixture becomes homogeneous. Next, except for using this mixture for forming a shaped body, a shaped body No. C4 is obtained in the same manner as in Example 1.

[0346] Tables 1-1 to 1-3 show the evaluation results of the shaped bodies according to Examples 1 to 17 and Comparative Examples 1 to 4.

[0347] [Table 1-1]

[0348]

[0349] In Tables 1-1 and 1-2, "same as above" means that the phase separation between the matrix and the domain is the same as in Example 1 or 9. The domain average diameter represents the arithmetic mean of the circular equivalent diameters of the domains. "Domain number %" is the ratio of the number of domains with a circularity of 0.60 to 0.95 to the total number of domains present in the observation region.

[0350] [Table 1-2]

[0351]

[0352] [Table 1-3]

[0353]

[0354] The results shown in Tables 1-1 to 1-3 will be described below.

[0355] Regarding the results of Evaluation 1, in the shaped bodies No. 1 to 17 according to Examples 1 to 17, clear phase separation between the matrix and the domain was observed. It was also confirmed that the matrix contains polyurethane having a first structure (a structure derived from polycarbonate), and the domain has a second structure (a structure derived from polyether).

[0356] Regarding the results of Evaluation 2, in each of the shaped bodies No. 1 to 17, the relationship between the parameter A representing the viscoelastic term of the domain and the parameter B representing the viscoelastic term of the matrix is A < B.

[0357] Regarding the results of Evaluation 3, in each of the molded bodies No. 1 to 17, it was confirmed that the relationship between the content C of the conductive filler per unit cross-sectional area and the content D of the conductive filler contained in the matrix per unit cross-sectional area was D / C ≥ 0.70. That is, it was confirmed that the conductive filler was mainly distributed in the matrix.

[0358] Conversely, in the molded body No. C1 according to Comparative Example 1, regarding the results of Evaluation 1, it was confirmed that the polyurethane having a structure derived from polyether was contained in the matrix, and the structure derived from polycarbonate was contained in the domain. Further, regarding the results of Evaluation 2, it was confirmed that the relationship between the parameters representing the viscoelastic terms was A > B. As a result of the above, the following tendency was observed: The elastic deformation power of the molded body No. C1 in which the matrix contained a structure derived from polyether with a large compression set was significantly lower than that of any of the molded bodies No. 1 to 17.

[0359] Comparing the molded body No. C1 with the molded body No. 1, it is considered that the reason for the inversion of the matrix and domain structures and the structure of the matrix being derived from polyether is that the amount of polycarbonate diol used to manufacture the molded body is relatively reduced compared to the amount of polyether diol, and the phase structure that can stably exist is changed.

[0360] For the molded body No. C2 according to Comparative Example 2, the conductive filler was in excess. As a result, it is considered that although the molded body has conductivity, it is impossible to achieve low hardness and low compression set.

[0361] For the molded body No. C3 according to Comparative Example 3, regarding the results of Evaluation 3, it was confirmed that the relationship between the content C and D of the conductive filler was D / C < 0.70, and the conductive filler was not mainly present in the matrix. Therefore, in the molded body No. C3, it was difficult to form a conductive path by adding the conductive filler. Therefore, although the addition amount of the conductive filler was approximate to that of any of the molded bodies No. 1 to 17, the molded body did not show conductivity (> 10 10 Ω·cm).

[0362] In addition, for the molded body No. C4 according to Comparative Example 4, regarding the results of Evaluation 1, phase separation between the matrix and the domain was not confirmed. Therefore, in the molded body No. C4, due to the uneven distribution of the conductive filler, it was difficult to form a conductive path by adding a small amount of the conductive filler. Therefore, although the addition amount of the conductive filler was approximate to that of any of the molded bodies No. 1 to 17, the molded body did not show conductivity (> 10 10 Ω·cm).

[0363] Furthermore, in the molded body No. C4, since the contribution of the structure derived from polyether to compression set becomes larger, the following tendency is shown: the elastic deformation power is significantly lower than that of the molded bodies No. 1 to 17.

[0364] It has become clear from the above results that the molded body according to the present disclosure can achieve low compression set, low hardness, and can have electrical conductivity. By unevenly distributing a small amount of electrically conductive filler in the phase-separated structure formed by arranging polycarbonate polyurethane in the matrix and arranging a structural unit softer than polycarbonate polyurethane in the domain, it is judged that these effects can be achieved.

[0365] The present disclosure is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present disclosure. Therefore, in order to show the scope of the present disclosure, the claims are attached herein.

[0366] This application claims priority based on Japanese Patent Application No. 2022-170591 filed on October 25, 2022, and Japanese Patent Application No. 2023-175847 filed on October 11, 2023, and the entire contents of the foregoing applications are incorporated herein by reference.

Claims

1. A shaped body comprising a polyurethane elastomer, and a conductive filler contained in the polyurethane elastomer, wherein the polyurethane elastomer has a matrix and domains dispersed in the matrix, the matrix having a first structure represented by the following formula (1), the domains have a second structure different from the first structure, the conductive filler is mainly distributed in the matrix, the relationship between parameter A and parameter B is A < B, where parameter A represents the viscoelastic term of the domains measured in a viscoelastic image by a scanning probe microscope on a cross-section of the shaped body exposing the domains and the matrix, and parameter B represents the viscoelastic term of the matrix measured in a viscoelastic image by a scanning probe microscope on a cross-section of the shaped body exposing the domains and the matrix, the content of the conductive filler in the shaped body is 0.02 to 5.0% by mass, The volume resistivity of the shaped body is 1.0×10 9 Ω·cm or less, and the Young's modulus of the shaped body is 0.5 to 4.0 MPa: [Chemical formula 1] wherein, In formula (1), R 1 represents a C3-12 alkylene group.

2. The shaped body according to claim 1, wherein R 1 is an alkylene group having 3 to 9 carbon atoms.

3. The shaped body according to claim 1 or 2, wherein the second structure is represented by the following formula (2): [Chemical formula 2] wherein, In formula (2), R 2 represents a C3-6 alkylene group.

4. The shaped body according to claim 3, wherein R 2 is a C3-5 alkylene group having a branched-chain structure.

5. The shaped body according to any one of claims 1 to 4, wherein the ratio D / C of the content D to the content C is D / C ≥ 0.80, where the content C is the total area of the conductive filler in each 30 μm × 30 μm observation region, and the content D is the total area of the conductive filler contained in the matrix in the observation region, and the observation region is observed in the cross-section.

6. The shaped body according to any one of claims 1 to 5, wherein the conductive filler is carbon black.

7. The shaped body according to any one of claims 1 to 6, wherein the area ratio of the matrix to the domains (matrix / domains) observed in a 50 μm × 50 μm observation region on the cross-section is 50 / 50 to 85 / 15.

8. The shaped body according to any one of claims 1 to 7, wherein the arithmetic mean of the circular equivalent diameters of the domains observed in the cross-section is 0.2 to 30.0 μm.

9. The shaped body according to any one of claims 1 to 8, wherein in the temperature-loss tangent (tanδ) curve obtained by dynamic viscoelastic measurement of the shaped body, there are at least two peaks originating from glass transition observed in the temperature range of -80°C to +20°C.

10. The shaped body according to claim 9, wherein at least one peak originating from glass transition is observed in the temperature range below -50°C, and at least one peak originating from glass transition is observed in the temperature range above -40°C.

11. The shaped body according to any one of claims 1 to 10, wherein the ratio (A / B) of parameter A to parameter B is 0.65 or less.

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