Vibration isolator

Abstract

To provide a vibration-proof device having a vibration-proof rubber composition in which change of characteristics caused by temperature change is suppressed.SOLUTION: The vibration isolator 10 includes a vibration isolation portion 13 made of a vibration isolation rubber composition containing a rubber material and a hydrogel whose hardness increases with a temperature rise. The vibration isolation device 10 preferably includes an outer cylinder 11, an inner cylinder 12, and a vibration isolation portion 13 connecting the outer cylinder 11 and the inner cylinder 12. It is also preferable that the vibration-isolating portion 13 has a first portion 131 made of the rubber material and a second portion 132 made of the hydrogel. It is also preferable that at least a part of the surface of the second portion 132 is in contact with the first portion 131 and extends continuously or discontinuously in an annular shape along the circumferential direction of the anti-vibration device 10.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an anti-vibration device. [Background technology]

[0002] The operating environment for anti-vibration rubber used in automobile suspensions is generally around -30°C to +50°C. Furthermore, the operating environment for anti-vibration rubber used in automobile engine mounts is generally around -30°C to +130°C. Because anti-vibration rubber softens as the temperature rises, its properties change between normal and high temperatures. As a result, the handling stability, ride comfort, and NVH performance of an automobile change depending on the outside temperature. To minimize these changes as much as possible, various innovations have been made to anti-vibration rubber in terms of the compounding of rubber materials.

[0003] For example, Patent Document 1 proposes a vibration-damping rubber composition containing a rubber component having a conjugated diene compound-non-conjugated olefin copolymer and a conjugated diene polymer, and carbon black having a specific iodine adsorption amount, with the aim of obtaining a vibration-damping rubber composition with excellent low-temperature properties. Patent Document 2 proposes that a 2,2,4-trimethyl-1,2-dihydroquinoline polymer be added to a diene rubber composition containing a rubber component made of a diene rubber and carbon black, in order to obtain a vibration-damping rubber composition having a low temperature dependency of elastic modulus. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-082822 [Patent Document 2] Japanese Patent Publication No. 2022-118764 Summary of the Invention [Problem to be solved by the invention]

[0005] Suppressing changes in the properties of anti-vibration rubber due to temperature changes through the formulation of rubber materials can sometimes result in a trade-off between the rubber material's properties, such as damping and dynamic magnification, and its durability. Furthermore, when a vehicle is driven on rough roads, the temperature rises due to heat generated by the rubber material itself, which can increase the amount of displacement of the anti-vibration rubber while driving. This can lead to a deterioration in the durability of the anti-vibration rubber. Thus, conventional technologies have not been able to adequately suppress changes in the properties of anti-vibration rubber due to temperature changes, making it difficult to achieve the desired performance regardless of the environmental temperature. Therefore, an object of the present invention is to suppress changes in the spring characteristics of the vibration-isolating portion of the vibration-isolating device due to temperature changes. [Means for solving the problem]

[0006] The present invention provides a vibration-isolating device having a vibration-isolating portion made of a vibration-isolating rubber composition containing a rubber material and a hydrogel whose hardness increases with increasing temperature. [Effects of the Invention]

[0007] According to the present invention, there is provided a vibration-isolating device having an anti-vibration rubber composition in which changes in spring characteristics caused by temperature changes are suppressed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1(a) is a vertical cross-sectional view showing one embodiment of the vibration isolation device of the present invention, and FIG. 1(b) is a cross-sectional view taken along line bb in FIG. 1(a). [Figure 2] 2(a) and 2(b) are longitudinal cross-sectional views showing deformation states of the vibration-isolating portion of the vibration-isolating device shown in FIG. 1(a) at low and high temperatures, respectively. [Figure 3] 3(a) to 3(d) are vertical cross-sectional views (equivalent to FIG. 1(a)) showing other embodiments of the vibration isolation device of the present invention. [Figure 4] FIG. 4 is a vertical cross-sectional view showing still another embodiment of the vibration isolation device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will now be described based on preferred embodiments with reference to the drawings. Figures 1(a) and 1(b) show one embodiment of a vibration isolation device of the present invention. The vibration isolation device 10 shown in these figures is generally called a vibration isolation bushing.

[0010] The vibration isolation device 10 has an outer cylinder 11 and an inner cylinder 12 disposed inside the outer cylinder 11. The outer cylinder 11 is attached to either a vibration generating part or a vibration receiving part. The inner cylinder 12 is attached to the other of the vibration generating part and the vibration receiving part. Examples of the vibration generating part include a suspension frame and a body frame, etc. Examples of the vibration receiving part include a body and a cabin, etc., which are provided above the vibration generating part, although it goes without saying that the vibration receiving part is not limited to these parts.

[0011] The vibration isolation device 10 is provided in a suspension system having a vibration generating unit, and is used to support a vibration receiving unit provided above the vibration generating unit. For example, an outer cylinder 11 is attached to the vibration generating unit, and an inner cylinder 12 is attached to the vibration receiving unit. A shaft-shaped member such as a fastening bolt (not shown) is inserted into the inner cylinder 12.

[0012] The outer cylinder 11 is cylindrical, and its inner and outer surfaces are curved to correspond to the inner and outer surfaces of the cylinder. Similarly, the inner cylinder 12 is cylindrical, and its inner and outer surfaces are curved to correspond to the inner and outer surfaces of the cylinder. The inner diameter of the outer cylinder 11 is larger than the outer diameter of the inner cylinder 12. The cross-sectional shapes of the inner and outer cylinders are not limited to circular shapes, but can be changed as appropriate based on the shapes of the vibration generating portion and the vibration receiving portion.

[0013] The vibration-isolating device 10 further includes a vibration-isolating portion 13 that connects the outer tube 11 and the inner tube 12. The vibration-isolating portion 13 is a portion made of a vibration-isolating rubber composition. The vibration-isolating portion 13 has a first portion 131 made of a rubber material and a second portion 132 made of a hydrogel. This hydrogel has the property of increasing hardness as the temperature rises. Details of the hydrogel will be described later. The first portion 131 is made essentially of a rubber material and does not contain a hydrogel. The second portion 132 is made essentially of a hydrogel and does not contain a rubber material.

[0014] 1 , in the vibration-isolating part 13, the second part 132 is embedded within the first part 131. Specifically, the second part 132 extends continuously in an annular shape along the circumferential direction of the inner cylinder 12, in other words, along the circumferential direction of the vibration-isolating device 10, so as to abut against the outer surface of the inner cylinder 12. In other words, the second part 132 has an annular shape. The annular second part 132 is held by the first part 131.

[0015] As described above, the second portion 132 of the vibration-isolating portion 13 is made of a hydrogel whose hardness increases with increasing temperature. When the temperature of this hydrogel is increased, a temperature is observed at which the hydrogel rapidly hardens. In the following explanation, this temperature is referred to as the "hardening temperature." The hardening temperature can be measured by measuring viscoelasticity using a rheometer. The specific measurement procedure will be described later. In this specification, the hardening of a hydrogel refers to the degree of deformation of the hydrogel, and the hardening of a hydrogel means that the hydrogel becomes less susceptible to deformation as the temperature increases.

[0016] On the other hand, the first portion 131 of the vibration-isolating portion 13 is made of a general rubber material, that is, an elastic material whose hardness decreases (i.e., softens) as the temperature rises. In other words, this rubber material does not include the hydrogel that makes up the second portion 132. As this rubber material, any rubber material similar to those conventionally used as vibration-isolating rubber for vibration-isolating devices can be used without any particular restrictions. Examples of such rubber materials include, but are not limited to, thermoplastic elastomers and thermosetting elastomers.

[0017] The mechanism of action of the vibration isolation device 10 having the above configuration will be described with reference to FIGS. 2(a) and 2(b). When the environment in which the vibration-isolating device 10 is used is low (for example, -30°C to 30°C), and an external force is applied to the vibration-isolating device 10 in the direction indicated by the arrow in Figure 2(a), the rubber material 131a in the vibration-isolating portion 13a located on the right side of the figure is difficult to deform due to the low temperature, but the hydrogel 132a held by the rubber material 131a is easy to deform due to the low temperature. As a result, the vibration-isolating portion 13a is sufficiently compressively deformed as a whole. The volume loss due to the compressive deformation of the vibration-isolating portion 13a is absorbed by the increase in volume of the rubber material 131b and hydrogel 132b in the vibration-isolating portion 13b located on the left side of the figure.

[0018] On the other hand, when the environment in which the vibration-damping device 10 is used is high temperature (for example, 30°C to 120°C), and an external force is applied to the vibration-damping device 10 in the direction shown by the arrow in Fig. 2(b), the rubber material 131a in the vibration-damping part 13a located on the right side in the figure is easily deformed due to the high temperature, but the hydrogel 132a held by the rubber material 131a is difficult to deform due to the high temperature. As a result, excessive compressive deformation of the vibration-damping part 13a as a whole is suppressed.

[0019] In this way, in the vibration-damping device 10, the vibration-damping portion 13 includes the first portion 131 and the second portion 132, which are two portions that deform to different degrees depending on the temperature, thereby suppressing changes in the spring characteristics of the vibration-damping portion 13 caused by changes in the usage environment of the vibration-damping device 10. In other words, the spring characteristics of the vibration-damping portion 13 are less likely to change with temperature changes.

[0020] To make the above advantages even more pronounced, the proportion of the second portion 132 in the vibration-isolating portion 13 is preferably 5 vol% or more, more preferably 7 vol% or more, and even more preferably 10 vol% or more, by volume. Also, the proportion of the second portion 132 in the vibration-isolating portion 13 is preferably 80 vol% or less, more preferably 70 vol% or less, and even more preferably 60 vol% or less, by volume.

[0021] The vibration-damping device 10 shown in FIG. 1 can be suitably manufactured by, for example, insert molding. Specifically, an outer cylinder 11 and an inner cylinder 12 are prepared, and a circular second portion 132 is attached to the outer surface of the inner cylinder 12. Next, the inner cylinder 12 with the outer cylinder 11 and the second portion 132 attached is placed at a predetermined position in a molding die. In this state, a rubber compound containing raw rubber (unvulcanized rubber), a vulcanizing agent, and other ingredients is charged into the mold, and heat and pressure are applied to crosslink the raw rubber. As a result, a first portion 131 made of a rubber material is formed to surround the second portion 132, and the desired vibration-damping device 10 is obtained.

[0022] Figures 3(a) to 3(d) show another embodiment of the vibration isolation device 10. Note that, with regard to the embodiment shown in these figures, the explanation of the embodiment shown in Figures 1 and 2 applies as appropriate to points that are not specifically explained. In Figures 3(a) to 3(d), the same members as those in Figures 1 and 2 are given the same reference numerals.

[0023] In the embodiment of the vibration damping device 10 shown in Figure 3(a), the second portion 132 of the vibration damping part 13 extends continuously in an annular shape along the circumferential direction of the outer cylinder 11, in other words, along the circumferential direction of the vibration damping device 10, so as to abut against the inner surface of the outer cylinder 11. The annular second portion 132 has a step portion 14 at the lower end of its outer surface (i.e., the surface facing the inner surface of the outer cylinder 11) that is cut out toward the vertical center line L of the vibration damping device 10. The step portion 14 is formed continuously along the circumferential direction of the second portion 132. Meanwhile, a rib 11a extending continuously in the circumferential direction is provided on the inner surface of the outer cylinder 11. The rib 11a protrudes toward the vertical center line L of the vibration-damping device 10. As shown in the figure, the rib 11a has a rectangular shape in vertical cross section. The cutout shape of the step portion 14 of the second portion 132 and the protruding shape of the rib 11a of the outer cylinder 11 are complementary to each other. Therefore, the step portion 14 and the rib 11a can be engaged with each other as shown in FIG. 3(a).

[0024] According to the vibration-damping device 10 of this embodiment, when insert molding is performed, the stepped portion 14 provided on the second portion 132 is engaged with the rib 11a provided on the inner surface of the outer cylinder 11, thereby making it possible to stably hold the second portion 132 on the inner surface of the outer cylinder 11. As a result, it becomes possible to perform insert molding stably. When holding the second portion 132, it is advantageous to heat the second portion 132 to increase its hardness before engaging it with the stepped portion 14.

[0025] In the embodiment of the vibration-damping device 10 shown in Figure 3(b), the second portion 132 of the vibration-damping part 13 extends continuously in an annular shape along the circumferential direction of the inner tube 12 so as to abut against the outer surface of the inner tube 12. The annular second portion 132 has a recessed portion 15 that is recessed radially outward of the vibration-damping device 10 in the central region in the height direction of its inner surface (i.e., the surface facing the outer surface of the inner tube 12). The step portion 14 is formed continuously along the circumferential direction of the second portion 132. Meanwhile, a rib 12a extending continuously along the circumferential direction is provided on the outer surface of the inner cylinder 12 in the central region in the height direction of the inner cylinder 12. The rib 12a protrudes outward in the radial direction of the vibration-damping device 10. As shown in the figure, the rib 12a has a rectangular cross section. The recessed shape of the recessed portion 15 of the second portion 132 and the protruding shape of the rib 12a of the inner cylinder 12 are complementary to each other. Therefore, the recessed portion 15 and the rib 12a can be engaged with each other as shown in FIG. 3(b).

[0026] According to the vibration-damping device 10 of this embodiment, when insert molding is performed, the recessed portion 15 provided in the second portion 132 is engaged with the rib 12a provided on the inner surface of the inner cylinder 12, thereby making it possible to stably hold the second portion 132 on the inner surface of the inner cylinder 12. As a result, it becomes possible to perform insert molding stably. During insert molding, it is advantageous to attach the second portion 132 at room temperature (i.e., in a softened state) to the inner cylinder 12, and then heat the second portion 132 to increase its hardness and perform insert molding in that state.

[0027] 3(c), the inner cylinder 12 has a recessed portion 12c on its outer surface, in a central region in the height direction of the inner cylinder 12, that is recessed toward the vertical center line L of the vibration damping device 10. The recessed portion 12c is formed continuously along the circumferential direction of the inner cylinder 12. A second portion 132 of the vibration-damping part 13 is fitted into the recessed portion 12c provided in the inner cylinder 12. The thickness T (see FIG. 3(c)) of the second portion 132 is greater than the depth of the recessed portion 12c. Therefore, the outer surface of the second portion 132 protrudes radially outward from the outer surface of the inner cylinder 12. According to the vibration-damping device 10 of this embodiment, when insert molding is performed, the second portion 132 is fitted into the recessed portion 12c provided on the outer surface of the inner cylinder 12, thereby making it possible to stably hold the second portion 132 on the outer surface of the inner cylinder 12. As a result, it becomes possible to perform insert molding stably. When performing insert molding, it is advantageous to attach the second portion 132 to the inner cylinder 12 while it is at room temperature (i.e., in a softened state), and then heat the second portion 132 to increase its hardness before insert molding.

[0028] In the embodiment of the vibration damping device 10 shown in Figure 3(d), the second part 132 has a cylindrical shape. The second part 132 is located between the first part 131 and the outer cylinder 11. The outer surface of the second part 132 contacts the inner surface of the outer cylinder 11. The inner surface of the second part 132 contacts the inner surface of the first part 131. The second portion 132 and the outer cylinder 11 are both cylindrical, and the height of the second portion 132 is the same as the height of the outer cylinder 11. Therefore, when manufacturing the vibration-damping device 10 of this embodiment by insert molding, when the inner cylinder 12, the second portion 132, and the outer cylinder 11 are placed in a mold, the height of the second portion 132 being the same as the height of the outer cylinder 11 causes at least a portion of the second portion 132 (for example, the bottom of the second portion 132) to come into contact with the mold and be stably held in the mold. As a result, insert molding can be performed stably. When holding the second portion 132, it is advantageous to heat the second portion 132 to increase its hardness before placing it in the mold.

[0029] FIG. 4 shows yet another embodiment of the vibration-damping device of the present invention. The vibration-damping device 20 shown in this figure includes a first support bracket 21 and a second support bracket 22, which are substantially identical circular thick metal plates. The first support bracket 21 has an attachment bolt 23 extending from its outer surface. Similarly, the second support bracket 22 has an attachment bolt 24 extending from its outer surface. The first and second support brackets 21, 22 are disposed opposite each other with the attachment bolts 23, 24 facing outward. A vibration-damping portion 13 is disposed between the support brackets 21, 22. The support brackets 21, 22 are elastically connected by the vibration-damping portion 13, which is made of a vibration-damping rubber composition. The shape of the vibration-damping portion 13 in cross section is, for example, circular. Therefore, the vibration-damping portion 13 is generally cylindrical. However, the shape of the vibration-damping portion 13 in cross section is not limited to a circular shape and may be a polygonal shape, such as a rectangle.

[0030] The vibration-isolating portion 13 has a first portion 131 made of a rubber material and a second portion 132 made of hydrogel. The first portion 131 exists over the region from the inner surface of the first support metal fitting 21 to the inner surface of the second support metal fitting 22. On the other hand, the second portions 132 are provided in two locations within the vibration-isolating portion 13. In detail, the second portions 132 are arranged on the inner surface of the first support bracket 21 at a position facing the mounting bolt 23, and are also arranged on the inner surface of the second support bracket 22 at a position facing the mounting bolt 24. One second portion 132 and the other second portion 132 are separated by the first portion 131. Each second portion 132 has a substantially cylindrical or rectangular columnar shape. Thus, the vibration-damping portion 13 in the vibration-damping device 20 of this embodiment has a three-layer laminated structure in which the second portion 132, the first portion 131, and the second portion 132 are laminated in this order when viewed along the vibration input direction (i.e., the direction connecting the first support bracket 21 and the second support bracket 22). In the vibration-damping device 10 of this embodiment, the vibration-damping portion 13 also has two portions, a first portion 131 and a second portion 132, which have different degrees of deformation depending on the temperature, and as a result, as in the previously described embodiments, changes in the spring characteristics of the vibration-damping portion 13 due to changes in the usage environment of the vibration-damping device 10 are suppressed.

[0031] Next, matters common to the above-described embodiments will be described. The hydrogel constituting the second portion 132 of the vibration-isolating portion 13 preferably contains a polymer having a carboxyl group and a divalent metal salt of an organic acid, from the viewpoint of further suppressing changes in the spring characteristics of the vibration-isolating portion 13 caused by changes in the environment in which the vibration-isolating device 10 is used. This hydrogel is a gel whose main components are a polymer having a carboxyl group and water or an aqueous solution.

[0032] The polymer having a carboxyl group (hereinafter also referred to as a "carboxyl group-containing polymer") is not particularly limited as long as it is an organic polymer compound having a carboxyl group. For example, it may be a homopolymer of a monomer having a carboxyl group, or a copolymer of multiple types of monomers including a monomer having a carboxyl group.

[0033] The monomer having a carboxyl group may be, for example, an α,β-unsaturated carboxylic acid containing one or more carboxyl groups in the molecule. Examples of such α,β-unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, aconitic acid, fumaric acid, and crotonic acid. These monomers may be used alone or in combination of two or more.

[0034] The homopolymer of a monomer having a carboxyl group may be, for example, polyacrylic acid or polymethacrylic acid, although it is not limited to these homopolymers. The copolymer of a monomer having a carboxyl group may be a copolymer obtained by polymerizing a plurality of types of monomers having a carboxyl group, or a copolymer obtained by polymerizing a monomer having a carboxyl group and a monomer other than the monomer having a carboxyl group. The monomer other than the monomer having a carboxyl group is not particularly limited, and may be, for example, at least one selected from the group consisting of acrylate monomers (e.g., α,β-ethylenically unsaturated carboxylic acid esters, hydroxyalkyl esters of α,β-ethylenically unsaturated carboxylic acids, and alkoxyalkyl esters of α,β-ethylenically unsaturated carboxylic acids), acrylamide monomers, and styrene monomers.

[0035] The acrylate monomer is not particularly limited, but examples thereof include the following (i) to (iii). (i) α,β-ethylenically unsaturated carboxylic acid esters such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, lauryl acrylate, and stearyl acrylate. (ii) Hydroxyalkyl esters of α,β-ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, and 3-hydroxypropyl methacrylate. (iii) Alkoxyalkyl esters of α,β-ethylenically unsaturated carboxylic acids such as diethylene glycol methacrylate.

[0036] The acrylamide monomer is not particularly limited, but examples thereof include acrylamide and methylol methacrylamide. The styrene-based monomer is not particularly limited, but examples thereof include styrene and alkylstyrene.

[0037] When the carboxyl group-containing polymer is a copolymer, it is preferable that 50 mol % or more of the monomers constituting the copolymer are derived from monomers having carboxyl groups, in order to improve the temperature responsiveness of the hydrogel. From this viewpoint, it is advantageous that 60 mol % or more, even more preferably 70 mol % or more, even more preferably 80 mol % or more, and most preferably 90 mol % or more of the monomers constituting the copolymer are derived from monomers having carboxyl groups.

[0038] The content of carboxyl groups in the carboxyl group-containing polymer is, for example, preferably 0.001 mol / g or more, more preferably 0.005 mol / g or more, and even more preferably 0.007 mol / g or more, in order to improve the temperature responsiveness of the hydrogel. From the same viewpoint, the content of carboxyl groups in the carboxyl group-containing polymer is preferably 0.05 mol / g or less, more preferably 0.03 mol / g or less, and even more preferably 0.014 mol / g or less.

[0039] The carboxyl group-containing polymer may have a crosslinked structure. The crosslinked structure may be a chemically crosslinked structure or a physically crosslinked structure. The chemically crosslinked structure may be formed by crosslinking using a crosslinking agent during or after polymer formation.

[0040] The cross-linking agent used to form the chemically cross-linked structure may be a difunctional or higher functional monomer, such as N,N'-methylenebisacrylamide, N,N'-ethylenebisacrylamide, diethylene glycol diacrylate, diethylene glycol dimethacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, and 1-acryloyloxy-3-methacryloyloxy-2-propanol.

[0041] A physically crosslinked structure is formed by the formation of a salt between two carboxyl groups in a carboxyl group-containing polymer and a divalent metal, and / or by entanglement of the carboxyl group-containing polymer. The former physically crosslinked structure is formed by forming a salt with a divalent metal on a carboxyl group-containing polymer formed without using a crosslinking agent. The phenomenon of physically cut hydrogels rejoining after cutting is mainly due to the formation of a salt between the carboxyl groups and the divalent metal. However, it is presumed that the entanglement of the carboxyl group-containing polymer progresses over a relatively long period of time, further reinforcing the rejoining due to salt formation. Note that a hydrogel with a chemically crosslinked structure can also be said to have a physically crosslinked structure, since two carboxyl groups in the carboxyl group-containing polymer form a salt with a divalent metal, and the carboxyl group-containing polymer is also entangled.

[0042] There is no particular limitation on the molecular weight of the carboxyl group-containing polymer. When the molecular weight of the carboxyl group-containing polymer is expressed as a mass average molecular weight, it is preferably 1,000,000 or less, and more preferably 500,000 or less. The lower limit of the mass average molecular weight is preferably 5,000 or more, and more preferably 10,000 or more. However, it may be practically impossible to measure the molecular weight of a polymer having a crosslinked structure.

[0043] Polymerization methods for preparing the carboxyl group-containing polymer include radical polymerization using a thermal initiator and photopolymerization using a photoinitiator. Of these polymerization methods, photopolymerization is preferred. Any known polymerization initiator can be used as appropriate. For example, a photoinitiator such as α-ketoglutaric acid can be used. Whether or not a carboxyl group-containing polymer forms a hydrogel is mainly related to the length of the polymer (in other words, the concentration of the polymerization initiator). Even if the polymer mass is the same, a higher concentration of the polymerization initiator increases the tendency for gelation. Therefore, the concentration of the polymerization initiator can be appropriately selected within the range that allows the formation of a hydrogel, depending on the type of polymerization initiator and the type of monomer. The amount of the polymerization initiator used can be, for example, 0.01 mol % or more and 10 mol % or less based on the monomer.

[0044] Next, the divalent metal salt of an organic acid used in combination with the carboxyl group-containing polymer will be described. The organic acid constituting the divalent metal salt of an organic acid is not particularly limited, but examples thereof include fatty acids (alicyclic carboxylic acids), aromatic carboxylic acids, oxocarboxylic acids, and other organic acids. Examples of fatty acids (alicyclic carboxylic acids) include formic acid, acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, isovaleric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, lauric acid, myristic acid, pentadecylic acid, palmitic acid, margaric acid, stearic acid, oleic acid, linoleic acid, linolenic acid, tuberculostearic acid, arachidic acid, arachidonic acid, eicosapentaenoic acid, behenic acid, docosahexaenoic acid, lignoceric acid, cerotic acid, montanic acid, and melissic acid. Aromatic carboxylic acids include, for example, salicylic acid, gallic acid, benzoic acid, phthalic acid, cinnamic acid, and mellitic acid. An example of an oxocarboxylic acid is pyruvic acid. Other organic acids include, for example, oxalic acid, lactic acid, tartaric acid, maleic acid, fumaric acid, malonic acid, succinic acid, malic acid, citric acid, aconitic acid, glutaric acid, adipic acid, amino acids, and L-ascorbic acid.

[0045] Considering the solubility and solubility curve of the salt, the organic acid is preferably one or more selected from the group consisting of formic acid, acetic acid, and propionic acid. For example, calcium formate exhibits a relatively small positive solubility curve in the range of 0 to 100°C (i.e., solubility increases with increasing temperature). In contrast, calcium acetate exhibits a negative solubility curve in the range of 0 to about 60°C, but a relatively small positive solubility curve in the range of about 50 to about 85°C. Calcium propionate exhibits a negative solubility curve in the range of 0 to about 50°C, but a positive solubility curve in the range of about 50 to 100°C. The divalent metal constituting the divalent metal salt of an organic acid is not particularly limited, but may be, for example, an element of Group 2. Examples of the element of Group 2 include calcium (Ca), magnesium (Mg), strontium (Sr), and barium (Ba).

[0046] In particular, it is preferable to use, as the divalent metal salt of an organic acid, salts of Group 2 elements such as calcium formate, calcium acetate, calcium propionate, magnesium formate, magnesium acetate and magnesium propionate.

[0047] The hydrogel is preferably produced by immersing a carboxyl group-containing polymer in an aqueous solution of a divalent metal salt of an organic acid. The concentration of the aqueous solution of the divalent metal salt of an organic acid can be, for example, in the range of 50 mmol / L or more to the saturated concentration, preferably in the range of 50 mmol / L to 500 mmol / L. The saturated concentration means the saturated amount (equal to the amount of carboxyl groups in the carboxyl group-containing polymer). The curing temperature of the hydrogel can be adjusted by adjusting the temperature of the aqueous solution of the divalent metal salt of an organic acid when the carboxyl group-containing polymer is immersed in the aqueous solution. The temperature of the aqueous solution of the divalent metal salt of an organic acid can be, for example, 4°C or higher and 30°C or lower. For chemically cross-linked gels, the immersion time is approximately 1 to 72 hours, and for physically cross-linked gels, the immersion time is approximately 2 to 7 days. However, if the desired physical properties are obtained, the immersion time until the equilibrium is reached is not necessary. The curing temperature of the hydrogel can also be adjusted by the concentration of the divalent metal in the hydrogel. When the divalent metal is, for example, calcium, the concentration of the divalent metal in the hydrogel is preferably in the range of about 1 mg to 100 mg per gram of hydrogel, more preferably about 10 mg to 70 mg, and even more preferably about 15 mg to 50 mg. The concentration of all metal ions in the hydrogel can be measured, for example, by inductively coupled plasma atomic emission spectrometry (ICP).

[0048] The curing temperature of the hydrogel can be controlled by adjusting the ratio of the carboxyl group-containing polymer and the divalent metal salt of an organic acid. The curing temperature can be measured by viscoelasticity measurements using a rheometer. Specifically, one side of a 15 mm diameter molded hydrogel is attached to the center of a stainless steel parallel plate using instant adhesive, and the other side is attached to a stainless steel rotating container. To prevent drying, the container is filled with a calcium acetate solution of the same concentration used to prepare the hydrogel. Viscoelasticity measurements are performed at a heating rate of 3°C / min, over a temperature range of 0°C to 95°C, with an applied shear frequency of 10 rad / s and a strain of 0.1%. The loss tangent Tanδ (G″ / G′) is calculated from the storage modulus G′ and loss modulus G″ obtained from the measurements, and the temperature at which Tanδ peaks is defined as the curing temperature.

[0049] For details regarding the hydrogel other than those described above, please refer to, for example, the disclosures of International Publication No. 2018 / 117165.

[0050] Although the present invention has been described above based on its preferred embodiments, the present invention is not limited to these embodiments. For example, in the above embodiment, the vibration-damping portion 13 is configured so that the first portion 131, which is made essentially of a rubber material, and the second portion 132, which is made essentially of a hydrogel, are clearly separated. However, instead, the vibration-damping portion 13 may be in a polymer blend state by mixing a rubber material and a hydrogel.

[0051] In addition, in the embodiment shown in Figures 1 to 3, a continuous, annular second portion 132 is provided along the inner surface of the outer tube 11 or the outer surface of the inner tube 12, but instead, the second portion 132 may be provided discontinuously to the extent that it can be considered to be annular.

[0052] In addition, in each of the above-described embodiments, a portion of the surface of second portion 132 is in contact with first portion 131, but instead, the entire surface of second portion 132 may be in contact with first portion 131. In other words, second portion 132 may be completely embedded in the first portion. [Explanation of symbols]

[0053] 10,20 Anti-vibration device 11 Outer cylinder 12 Inner cylinder 13, 13a, 13b Vibration isolation parts 131 Part 1 132 Part 2 131a, 131b rubber material 132a,132b Hydrogel

Claims

1. A vibration-isolating device having a vibration-isolating portion made of a vibration-isolating rubber composition containing a rubber material and a hydrogel whose hardness increases with increasing temperature.

2. The vibration isolation device according to claim 1 , wherein the hydrogel contains a polymer having a carboxyl group and a divalent metal salt of an organic acid.

3. 3. The vibration-damping device according to claim 2, wherein the polymer having a carboxyl group is a polymer of one or more monomers selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, aconitic acid, fumaric acid, and crotonic acid.

4. 4. The vibration isolation device according to claim 3, wherein the polymer having a carboxyl group is a homopolymer of acrylic acid or methacrylic acid.

5. 3. The vibration isolation device according to claim 2, wherein the organic acid is one or more selected from the group consisting of formic acid, acetic acid, and propionic acid.

6. 3. The vibration isolation device of claim 2, wherein the divalent metal salt is a salt of a Group 2 element.

7. 2. The vibration isolation device according to claim 1, wherein the rubber material softens as the temperature rises.

8. 8. The vibration isolation device according to claim 7, wherein the rubber material is a thermoplastic elastomer or a thermosetting elastomer.

9. an outer cylinder attached to either the vibration generating unit or the vibration receiving unit; an inner cylinder attached to the other and disposed inside the outer cylinder; the vibration-isolating portion connecting the outer cylinder and the inner cylinder, the vibration-isolating portion has a first portion made of the rubber material and a second portion made of the hydrogel, The vibration-damping device according to claim 1 , wherein the second portion has at least a portion of its surface in contact with the first portion and extends continuously or discontinuously in an annular shape along the circumferential direction of the vibration-damping device.

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