Base isolation rubber laminate

Abstract

The present invention provides a base isolation rubber laminate with excellent damping characteristics.　Provided is a base isolation rubber laminate having a rubber layer formed from a vulcanized body of a rubber composition for a base isolation rubber laminate containing the following component (A) and component (B), wherein the number of aggregates in which three or more calcium carbonate particles are connected is in the range of 3-15, the aggregates being contained in any 1 μm × 1 μm square region of a scanning transmission electron microscope image of the rubber layer taken at a magnification of 150,000x.　(A) Isoprene rubber and / or butadiene rubber (B) Calcium carbonate

Description

Seismic isolation rubber laminate

[0001] The present invention relates to a seismic isolation rubber laminate. Specifically, it relates to a seismic isolation rubber laminate for supporting civil engineering and building structures.

[0002] Conventionally, seismic isolation rubber laminates (rubber bearings) have been used for supporting structures in fields such as civil engineering and architecture. For example, some seismic isolation rubber laminates are arranged to be interposed between the superstructure and the substructure of a structure such as a building.

[0003] A seismic isolation rubber laminate usually has a laminate structure in which a rigid plate such as a metal plate and a rubber layer are alternately laminated. Specifically, for example, as shown in FIG. 1, in the seismic isolation rubber laminate 10, a plurality of metal plates 14 as rigid plates are buried in the rubber block 12 at a predetermined interval, so that such metal plates 14 and the rubber layer 16 which is the rubber block 12 portion located between these metal plates 14, 14 are alternately and integrally laminated. Also, on the upper and lower portions of the rubber block 12, metal upper mounting plates 18 and lower mounting plates 20 are fixed respectively. When these seismic isolation rubber laminates are installed in the foundation part of a building, the shaking of an earthquake is not directly transmitted to the building, the shaking of the upper floors is also alleviated, the period of the shaking becomes longer, and a desired seismic isolation effect is achieved.

[0004] Japanese Patent No. 4120602

[0005] Conventionally, various studies have been conducted from the viewpoint of improving the damping characteristics of seismic isolation rubber laminates. However, the fact is that the research on the relationship between the dispersion form of fillers in the rubber layer of seismic isolation rubber laminates and the damping characteristics, especially the relationship between the dispersion form of calcium carbonate and the damping characteristics, has not yet progressed sufficiently.

[0006] The present invention has been made in view of such circumstances, and provides a seismic isolation rubber laminate having excellent damping characteristics.

[0007] The inventors, in the process of investigating combinations of polymer and filler components from the viewpoint of improving damping characteristics among the various properties of seismic isolation rubber laminates, focused on the dispersion form of calcium carbonate in the polymer matrix of isoprene rubber and / or butadiene rubber. In the process of diligently conducting research from this viewpoint, the inventors discovered a new and different finding regarding the relationship between the dispersion form of calcium carbonate and damping characteristics. That is, conventionally, it was generally considered preferable to increase the dispersibility of calcium carbonate in the polymer matrix, i.e., to minimize the proportion of aggregated particles, in order to improve various properties, but the inventors newly discovered that, in the dispersion form of calcium carbonate in the polymer matrix of isoprene rubber and / or butadiene rubber, the damping characteristics are actually inhibited as the dispersibility increases. Based on these new findings, the inventors conducted further research and discovered that by having a specific dispersion form, namely, a state in which three or more calcium carbonate particles are linked together, and by controlling the number of aggregates of three or more linked calcium carbonate particles within a specific range, the damping characteristics of the rubber layer in a seismic isolation rubber laminate can be effectively improved.

[0008] In other words, the gist of the present invention is as follows: [1] A seismic isolation rubber laminate having a rubber layer made of a vulcanized body of a rubber composition for seismic isolation rubber laminates containing the following components (A) and (B), wherein the number of aggregates of three or more calcium carbonate particles in any 1 μm × 1 μm square region of a scanning transmission electron microscope image of the rubber layer taken at a magnification of 150,000 is in the range of 5 to 15. (A) At least one of isoprene rubber and butadiene rubber (B) Calcium carbonate [2] The seismic isolation rubber laminate according to [1], wherein the number of aggregates of three or more calcium carbonate particles is in the range of 6 to 10. [3] The seismic isolation rubber laminate according to [1] or [2], wherein the content of component (B) is 25 to 80 parts by mass per 100 parts by mass of component (A). [4] The seismic isolation rubber laminate according to any one of [1] to [3], wherein the component (A) above contains isoprene rubber, and the isoprene rubber content is 70% by mass or more of the total amount of rubber components contained in the rubber composition for the seismic isolation rubber laminate.

[0009] According to the present invention, a seismic isolation rubber laminate with excellent damping characteristics can be provided.

[0010] This is an explanatory diagram showing a typical example of a seismic isolation rubber laminate. This is a schematic diagram of the apparatus used to perform the evaluation method described in the example. This is a diagram showing the load-strain loop curve in the evaluation method described in the example. This is a diagram showing a scanning transmission electron microscope image of Example 1. This is a diagram showing an elemental mapping image of Example 1. This is a diagram showing a magnified image (1 μm × 1 μm square area) of the scanning transmission electron microscope image of Example 1.

[0011] Next, embodiments of the present invention will be described in detail. However, the present invention is not limited to these embodiments.

[0012] In this specification, "X or / and Y (where X and Y are any configuration)" means at least one of X and Y, and can mean X only, Y only, or X and Y. Furthermore, in the numerical ranges described in steps in this specification, the upper or lower limit of one step in the numerical range can be arbitrarily combined with the upper or lower limit of another step in the numerical range. In addition, in the numerical ranges described in this specification, the upper or lower limit of that numerical range can be replaced with the values ​​shown in the examples.

[0013] A seismic isolation rubber laminate according to one embodiment of the present invention (hereinafter sometimes referred to as "this rubber laminate") is a seismic isolation rubber laminate having a rubber layer made of a vulcanized body of a rubber composition for seismic isolation rubber laminates (hereinafter sometimes referred to as "this rubber composition") containing the following components (A) and (B), characterized in that the number of aggregates of three or more calcium carbonate particles in any 1 μm × 1 μm square region of a scanning transmission electron microscope image of the rubber layer taken at a magnification of 150,000 is in the range of 5 to 15. (A) At least one of isoprene rubber and butadiene rubber (B) Calcium carbonate

[0014] According to this rubber laminate, in the rubber layer made up of a vulcanized rubber composition containing at least one of isoprene rubber and butadiene rubber and calcium carbonate, the calcium carbonate particles are dispersed in a different form than in conventional materials, resulting in excellent damping characteristics.

[0015] Specifically, by setting the number of aggregates, each consisting of three or more calcium carbonate particles, in any 1 μm × 1 μm area of ​​a scanning transmission electron microscope image of a rubber layer made from a vulcanized rubber composition containing at least one of isoprene rubber and butadiene rubber, and calcium carbonate, at a magnification of 150,000x, to the range of 5 to 15, excellent damping characteristics can be obtained. If the number of aggregates is outside the above range, it is not possible to obtain the excellent damping characteristics of the present invention. For example, if there are almost no aggregates, as was previously considered preferable, for example, if the aggregates are dispersed to less than 5, it is not possible to obtain the excellent damping characteristics of the present invention.

[0016] Furthermore, in a preferred embodiment of this rubber laminate, it is preferable to set the number of aggregates to a range of 6 to 12 or 6 to 10, from the viewpoint of exhibiting particularly excellent damping characteristics.

[0017] The number of calcium carbonate particles forming the aggregate is not particularly limited as long as there are three or more, but for example, the number of calcium carbonate particles forming the aggregate is about 3 to 12 or 3 to 10. In one embodiment of the present invention, for example, the number of aggregates, each consisting of 3 to 12 calcium carbonate particles, is in the range of 5 to 15.

[0018] The reason why the above-mentioned excellent effects are obtained by this rubber laminate is not entirely clear, but the inventors believe that in order to exhibit excellent damping properties, it is necessary to effectively generate frictional force. In the present invention, in a polymer matrix containing at least one of isoprene rubber and butadiene rubber, the frictional force is significantly improved by friction between aggregates containing three or more calcium carbonate particles. In addition, the interparticle attractive force of the calcium carbonate particles constituting the aggregates and the mutual frictional effect between the calcium carbonate particles and specific polymer components combine to further significantly improve the frictional force, thereby obtaining excellent damping characteristics. Furthermore, noting that poor dispersion of calcium carbonate and too many aggregates tend to make it difficult to exhibit frictional damping, and conversely, too good dispersion requires a certain level of displacement to exhibit frictional damping, the inventors believe that in the present invention, by controlling the number of specific aggregates within a specific range, the frictional damping effect can be synergistically expressed, thus obtaining excellent damping characteristics.

[0019] The number of aggregates can be determined according to a standard method, as described below. Specifically, a smooth surface of the rubber layer is prepared using a microtome, a 1 μm × 1 μm area is identified in the scanning transmission electron microscope image taken at a magnification of 150,000x, and the number of aggregates consisting of three or more calcium carbonate particles is counted by visually observing this area.

[0020] Specifically, for example, first, the rubber layer is observed using a scanning transmission electron microscope (SEM) at a magnification of 150,000x, and a SEM image is acquired. Next, an elemental mapping image is acquired using an energy-dispersive X-ray spectrometer attached to the SEM, and calcium carbonate is identified in the microscope image by detecting Ca atoms derived from calcium carbonate. Then, the elemental mapping image and a magnified image of the electron microscope image are compared, and the number of aggregates contained in a 1 μm x 1 μm area within the electron microscope image is visually measured.

[0021] Furthermore, in this specification, "aggregates of three or more calcium carbonate particles" observed in scanning transmission electron microscope images means aggregates comprising at least a first calcium carbonate particle, a second calcium carbonate particle in contact with the first calcium carbonate particle, and a third calcium carbonate particle in contact with at least one of the first and second calcium carbonate particles. Specifically, it is an aggregate in which the outline of the first calcium carbonate particle and the outline of the second calcium carbonate particle are in contact, and which comprises at least a third calcium carbonate particle in contact with the first and second calcium carbonate particles.

[0022] Furthermore, the term "aggregate of three or more calcium carbonate particles" observed in scanning transmission electron microscope images implies not only that the calcium carbonate particles are in contact, but also that the interparticle distance is within 20 nm, considering the interparticle attractive forces of calcium carbonate particles. In other words, if the interparticle distance between any two calcium carbonate particles is within 20 nm, they can be considered to be in contact due to chemical and physical interparticle attractive forces. Therefore, an aggregate containing at least a first calcium carbonate particle, a second calcium carbonate particle whose interparticle distance from the first calcium carbonate particle is within 20 nm, and a third calcium carbonate particle whose interparticle distance from the first calcium carbonate particle and at least one of the second calcium carbonate particles is within 20 nm can be considered an "aggregate of three or more calcium carbonate particles." More specifically, if the shortest straight-line distance between the outlines of any two calcium carbonate particles is 20 nm or less, or more precisely, if the shortest straight-line distance between any point constituting the outline of any two calcium carbonate particles and any point constituting the outline of another two calcium carbonate particles is 20 nm or less, then the two calcium carbonate particles can be considered to be in contact with each other, and are therefore considered to be an aggregate of three or more connected calcium carbonate particles.

[0023] The following provides a detailed description of this rubber composition and rubber laminate.

[0024] (A) At least one of isoprene rubber and butadiene rubber This rubber composition contains at least one of isoprene rubber (IR) and butadiene rubber (BR). In this rubber composition, from the viewpoint of exhibiting excellent damping characteristics, it is particularly important to use isoprene rubber (IR) and / or butadiene rubber (BR) among the various rubber components.

[0025] (Isoprene rubber (IR)) The isoprene rubber (IR) used in this rubber composition may be any isoprene rubber (IR) that is conventionally known in the art. Isoprene rubber (IR) is a rubber obtained by polymerizing isoprene as a raw material monomer, and can be obtained, for example, by polymerizing isoprene using a Ziegler catalyst or an alkyllithium initiator.

[0026] The microstructure of isoprene rubber (IR) is not particularly limited, but the content of cis-1,4 linkage units can be, for example, 90% by mass or more, 94% by mass or more, or 96% by mass or more.

[0027] Mooney viscosity (ML) of isoprene rubber (IR) 1+4 The temperature (100°C) is not particularly limited, but for example, it is around 50-200°C, 60-150°C, or 70-100°C.

[0028] (Butadiene Rubber (BR)) The butadiene rubber (BR) used in this rubber composition may be any that is conventionally known in the art. Butadiene rubber (BR) is a rubber obtained by polymerizing butadiene as a raw material monomer, and can be obtained, for example, by polymerizing butadiene using a Ziegler catalyst or an alkyllithium initiator.

[0029] The microstructure of butadiene rubber (BR) is not particularly limited, but low-cis-BR with a cis-1,4 bond unit content of 50% by mass or less, for example, 30-40% by mass, or high-cis-BR with 90% by mass or more, can be used as appropriate.

[0030] Butadiene rubber (BR) Mooney viscosity (ML1+4 (100°C) is not particularly limited, but for example, it is around 30-60, 30-55, or 30-50.

[0031] The above Mooney viscosity is measured in accordance with the provisions of JIS K6300-1:2013, using an L-shaped rotor, with a preheating time of 1 minute, rotor rotation time of 4 minutes, and a test temperature of 100°C.

[0032] Examples of commercially available isoprene rubber (IR) and butadiene rubber (BR) include products from companies such as Zeon Corporation, UBE Elastomers, ENEOS Materials, and Asahi Kasei Corporation.

[0033] Furthermore, it is preferable that the rubber composition uses a rubber component mainly composed of isoprene rubber (IR) and / or butadiene rubber (BR). The term "main component" above means a component that accounts for 55% by mass or more of the total amount (100% by mass) of rubber components contained in the rubber composition. Therefore, it is preferable that the content of isoprene rubber (IR) and / or butadiene rubber (BR) in the total amount (100% by mass) of rubber components contained in the rubber composition be 55% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and may also be 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass.

[0034] This rubber composition may optionally contain rubbers other than isoprene rubber (IR) and butadiene rubber (BR). Examples of such rubbers include, but are not limited to, natural rubber (NR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), and diene rubbers such as butyl rubber (IIR). These may be used individually or in combination of two or more.

[0035] Furthermore, in one embodiment of the rubber composition, it is preferable that 55% or more by mass of the total amount (100% by mass) of rubber components contained in the rubber composition is isoprene rubber (IR), and the isoprene rubber (IR) content may be 60% or more by mass, 70% or more by mass, 80% or more by mass, 90% or more by mass, 95% or more by mass, or 100% by mass of the total amount (100% by mass) of rubber components contained in the rubber composition.

[0036] (B) Calcium Carbonate: It is important that this rubber composition contains calcium carbonate, among various fillers, along with component (A). Furthermore, as mentioned above, it is important that the calcium carbonate has a specific dispersion form.

[0037] As the calcium carbonate, any calcium carbonate conventionally known in the art can be used as appropriate. Although not particularly limited, from the viewpoint of significantly achieving the effects of the present invention, calcium carbonate that has undergone surface treatment such as hydrophobic treatment may be used. Specifically, for example, stearic acid-treated calcium carbonate, rosin acid-treated calcium carbonate, lignin-treated calcium carbonate, fatty acid quaternary ammonium salt-treated calcium carbonate, etc. may be used.

[0038] The average particle size (average primary particle size) of calcium carbonate is not limited to the following, but is for example 0.01 to 0.2 μm, preferably 0.02 to 0.19 μm, and more preferably 0.03 to 0.18 μm. The average particle size (average primary particle size) can be calculated using a scanning transmission electron microscope.

[0039] The BET specific surface area of ​​calcium carbonate is not limited to the following, but for example, 10 to 80 m². 2 The value is / g, preferably 15 to 75m 2 / g, more preferably 20 to 60 m 2 The value is / g. The BET specific surface area of ​​calcium carbonate can be measured, for example, by degassing the sample at 200°C for 15 minutes, and then using a BET specific surface area analyzer (Microdata Corporation, 4232-II) with a mixed gas (N2: 70%, He: 30%) as the adsorbed gas.

[0040] The DBP (dioctyl phthalate) oil absorption of calcium carbonate is not limited to the following, but for example, it is 10 to 80 cc / 100 g, preferably 15 to 75 cc / 100 g, more preferably 20 to 60 cc / 100 g.

[0041] From the viewpoint of easily controlling the above aggregates within a suitable range, the content of calcium carbonate is, for example, 10 to 80 parts by mass, preferably 15 to 75 parts by mass, more preferably 20 to 70 parts by mass with respect to 100 parts by mass of the component (A).

[0042] 《Other Optional Components》 In addition to the above components (A) and (B), the rubber composition may be blended with a plasticizer, a vulcanizing agent, a vulcanization accelerator, an antioxidant, a filler such as carbon black, etc. within a range that does not inhibit the effects of the present invention. These may be used alone or in combination of two or more.

[0043] Note that the content of the component (A) in the rubber composition is not limited, but for example, it is 30 to 70% by mass, preferably 32 to 68% by mass, more preferably 34 to 65% by mass, etc. with respect to the total amount (100% by mass) of the rubber composition.

[0044] (Plasticizer) Examples of the plasticizer include ester-based plasticizers such as adipic acid ester-based plasticizers, phosphoric acid ester-based plasticizers, sebacic acid ester-based plasticizers, and phthalic acid ester-based plasticizers. Among these, adipic acid ester-based plasticizers are preferred.

[0045] Examples of the adipic acid ester-based plasticizer include dimethyl adipate, diethyl adipate, dibutyl adipate, diheptyl adipate, diisononyl adipate, dioctyl adipate, diisooctyl adipate, di-2-ethylhexyl adipate, dinonyl adipate, diisononyl adipate, diisodecyl adipate, ditridecyl adipate, dibutylpentyl adipate, and dicyclohexyl adipate.

[0046] Other examples of the plasticizer include hydrocarbon-based plasticizers. Examples of the hydrocarbon-based plasticizer include paraffin-based hydrocarbons and olefin-based hydrocarbons.

[0047] Examples of olefinic hydrocarbons include poly-α-olefins. Poly-α-olefins are, for example, obtained by polymerizing α-olefins having 6 to 16 carbon atoms.

[0048] The content of the plasticizer is not particularly limited, but is, for example, 1 to 40 parts by mass, preferably 5 to 35 parts by mass, and more preferably 10 to 30 parts by mass, per 100 parts by mass of component (A).

[0049] Examples of vulcanizing agents include sulfur (powdered sulfur, precipitated sulfur, insoluble sulfur). The content of the vulcanizing agent is not particularly limited, but is, for example, 0.1 to 7 parts by mass, preferably 0.3 to 6 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of component (A).

[0050] Examples of vulcanization accelerators include thiazole-based, sulfenamide-based, thiram-based, aldehyde ammonia-based, aldehyde amine-based, guanidine-based, and thiourea-based vulcanization accelerators. The content of the vulcanization accelerator is not particularly limited, but is, for example, 0.1 to 7 parts by mass, preferably 0.1 to 5 parts by mass, more preferably 0.3 to 4 parts by mass, and even more preferably 0.5 to 3 parts by mass, per 100 parts by mass of component (A).

[0051] Examples of thiazole-based vulcanization accelerators include dibenzothiadyl disulfide (MBTS), 2-mercaptobenzothiazole (MBT), 2-mercaptobenzothiazole sodium salt (NaMBT), and 2-mercaptobenzothiazole zinc salt (ZnMBT). The content of the thiazole-based vulcanization accelerator is not limited, but is, for example, 0.1 to 7 parts by mass, preferably 0.3 to 6 parts by mass, and more preferably 0.5 to 5 parts by mass, per 100 parts by mass of component (A).

[0052] Examples of sulfenamide-based vulcanization accelerators include N-oxydiethylene-2-benzothiazolylsulfenamide (NOBS), N-cyclohexyl-2-benzothiazolylsulfenamide (CBS), N-t-butyl-2-benzothiazolylsulfenamide (BBS), and N,N'-dicyclohexyl-2-benzothiazolylsulfenamide. The content of the sulfenamide-based vulcanization accelerator is not limited, but is, for example, 0.1 to 3 parts by mass, preferably 0.3 to 2.5 parts by mass, and more preferably 0.5 to 2 parts by mass, per 100 parts by mass of component (A).

[0053] Examples of thiram-based vulcanization accelerators include tetramethylthiram disulfide (TMTD), tetraethylthiram disulfide (TETD), tetrabutylthiram disulfide (TBTD), tetrakis(2-ethylhexyl)thiram disulfide (TOT), and tetrabenzylthiram disulfide (TBzTD). The content of the thiram-based vulcanization accelerator is not limited, but is, for example, 0.1 to 5 parts by mass, preferably 0.3 to 4 parts by mass, and more preferably 0.5 to 3 parts by mass, per 100 parts by mass of component (A).

[0054] Examples of vulcanization aids include zinc oxide, zinc oxide (ZnO), stearic acid, and magnesium oxide. The content of the vulcanization aid is not particularly limited, but is, for example, 1 to 15 parts by mass, preferably 2 to 13 parts by mass, and more preferably 3 to 10 parts by mass, per 100 parts by mass of component (A).

[0055] Examples of anti-aging agents include carbamate-based anti-aging agents, phenylenediamine-based anti-aging agents, phenol-based anti-aging agents, diphenylamine-based anti-aging agents, quinoline-based anti-aging agents, imidazole-based anti-aging agents, and waxes. The content of the anti-aging agent is not particularly limited, but is, for example, 0.1 to 15 parts by mass, preferably 0.5 to 12 parts by mass, and more preferably 1 to 10 parts by mass, per 100 parts by mass of component (A).

[0056] Examples of fillers include carbon black, silica, talc, carbon fibers, and carbon nanotubes. Among these, carbon black is preferred. The carbon black is not limited to the following, but for example, it has a DBP oil absorption capacity of 100 to 150 ml / 100 g, an iodine adsorption capacity of 150 to 200 mg / g, and a nitrogen adsorption specific surface area of ​​140 to 200 m². 2 A carbon black of / g is preferred.

[0057] The amount of iodine adsorbed by carbon black is measured in accordance with JIS K6217-1 (Method A). The amount of DBP absorbed by carbon black is measured in accordance with JIS K6217-4. In addition, the specific surface area for nitrogen adsorption of the above carbon black is measured in accordance with JIS K6217-2.

[0058] The filler content is not particularly limited, but is, for example, 20 to 150 parts by mass, preferably 30 to 140 parts by mass, and more preferably 40 to 130 parts by mass, per 100 parts by mass of component (A).

[0059] (Method for preparing the rubber composition) The rubber composition can be obtained by kneading, for example, component (A), component (B), and other components as needed, using a kneader, planetary mixer, mixing roll, twin-screw agitator, etc.

[0060] As described above, this rubber laminate is characterized in that, in any 1 μm × 1 μm area of ​​a scanning transmission electron microscope image of the rubber layer taken at a magnification of 150,000, the number of aggregates, which are clusters of three or more calcium carbonate particles, is in the range of 5 to 15. By controlling the number of aggregates to the range of 5 to 15, excellent damping characteristics can be achieved.

[0061] The method for controlling the number of aggregates within the above range is not particularly limited, but examples include adjusting the number of kneading cycles within a certain range or adjusting the kneading temperature within a certain range when preparing the rubber composition.

[0062] Among these methods, a method of adjusting the number of kneading cycles within a certain range is preferred when preparing the rubber composition. Specifically, for example, a method of adjusting the number of times the materials excluding the vulcanizing agent and vulcanization accelerator, such as sulfur, are kneaded within a certain range is preferred, as is a method of adjusting the rubber discharge temperature after kneading within a certain range.

[0063] More specifically, the method for preparing a rubber composition comprises a first step of mixing components (A) and (B) to prepare a masterbatch, a second step of adding materials excluding the vulcanizing agent and vulcanization accelerator to the masterbatch and kneading, and a third step of adding the vulcanizing agent and vulcanization accelerator and kneading, wherein in the first step, kneading at 100 to 160°C for 1 to 10 minutes (preferably 110 to 150°C for 3 to 8 minutes) is repeated 2 to 6 times (preferably 2 to 5 times), and further, from the viewpoint of controlling the discharge temperature, in the third step, kneading at 40 to 110°C for 1 to 10 minutes (preferably 50 to 100°C for 3 to 8 minutes) is preferred. For example, if the first step is performed with fewer kneading times than described above, the number of aggregates tends to be greater than the range defined in the present invention, and the decay characteristics tend to be insufficient. Conversely, if the first step is performed more times than the number of kneading cycles mentioned above, the number of aggregates tends to be less than the range specified in this invention, and the damping characteristics tend to be insufficient.

[0064] (Method for Manufacturing Seismic Isolation Rubber Laminates) A ​​seismic isolation rubber laminate has a rubber layer made of a rubber composition for seismic isolation rubber laminates and a layer made of a metal plate. Various known methods are used as appropriate when manufacturing seismic isolation rubber laminates. Specifically, for example, a method is used in which the rubber composition is placed in the presence of upper and lower mounting plates together with a metal plate using a vulcanizing mold, and a rubber block is vulcanized and molded so that a rubber layer is interposed between the metal plates and the rubber layer is integrally vulcanized and bonded. Alternatively, a seismic isolation rubber laminate can be manufactured by alternately laminating and bonding the metal plate and the rubber layer formed from the rubber composition using a suitable adhesive to integrate them.

[0065] For example, to obtain the seismic isolation rubber laminate 10 shown in Figure 1, one method is to knead a predetermined rubber composition using a closed-type kneader or the like, then use a vulcanizing mold to place the predetermined rubber composition in the presence of a predetermined metal plate 14 or upper and lower mounting plates 18, 20 together with it, and vulcanize the rubber block 12, thereby creating a structure in which a rubber layer 16 is interposed between the metal plates 14, 14 and integrally vulcanized and bonded. Alternatively, a method can be employed in which the metal plates 14 and the rubber layer 16 formed from the rubber composition are alternately laminated and bonded using a suitable adhesive to form a laminate.

[0066] In the seismic isolation rubber laminate of the present invention, iron plates or steel plates with excellent compression resistance can be suitably used as the metal plate 14, but other metal materials may also be used, and even hard plastic plates can be used as long as they have excellent compression resistance.

[0067] Furthermore, the overall shape of the seismic isolation rubber laminate 10 is not particularly limited, and an appropriate shape can be adopted depending on the installation method. For example, in the planar form, in addition to a square or disc shape, polygonal shapes such as an ellipse, pentagon, or hexagon can be used. Also, the number of layers of metal plates 14 and rubber layers 16 can be appropriately determined according to the application of the seismic isolation rubber laminate.

[0068] Next, examples will be described together with comparative examples. However, the present invention is not limited to these examples unless it exceeds the essence of the invention.

[0069] (Example 1) The target rubber composition was prepared by blending each component shown in Table 1 in the proportions shown in the same table. Specifically, the rubber composition was prepared through three steps: a first step of mixing isoprene rubber and calcium carbonate to prepare a masterbatch; a second step of adding materials excluding the vulcanizing agent (sulfur) and vulcanization accelerator to the masterbatch and kneading; and a third step of adding the vulcanizing agent and vulcanization accelerator and kneading. The first step was performed by repeating kneading at 130°C for 10 minutes three times using a kneader. In the second step, materials excluding the vulcanizing agent and vulcanization accelerator were added to the masterbatch prepared in the first step and kneaded at 130°C for 10 minutes using a kneader. In the third step, kneading was performed at 40°C for 10 minutes using a mixing roll.

[0070] (Example 2) The rubber composition of Example 2 was prepared in the same manner as in Example 1, except that isoprene rubber was replaced with butadiene rubber.

[0071] (Example 3) The rubber composition of Example 3 was prepared in the same manner as in Example 2, except that the number of kneading steps in the first step was changed to two.

[0072] (Example 4) The rubber composition of Example 4 was prepared in the same manner as in Example 2, except that the number of kneading steps in the first step was changed to five.

[0073] (Comparative Example 1) A rubber composition of Comparative Example 1 was prepared in the same manner as in Example 2, except that the number of kneading steps in the first step was changed to one.

[0074] (Comparative Example 2) A rubber composition for Comparative Example 2 was prepared in the same manner as in Example 2, except that the number of kneading steps in the first step was changed to eight.

[0075] [Measurement test of the number of calcium carbonate aggregates] From each rubber composition obtained as described above, vulcanized rubber test pieces (S1 type) specified in JIS K6394:1976 "Test method for dynamic properties of vulcanized rubber" were prepared by adopting vulcanization conditions of 150°C for 30 minutes.

[0076] [Measurement of the number of aggregates consisting of three or more calcium carbonate particles] Using a microtome (Leica, EM UC7), smooth surfaces were prepared for the rubber test pieces of the examples and comparative examples. Using a scanning transmission electron microscope (JEOL, JEM-2800), scanning transmission electron microscope images were acquired at four locations on the rubber test pieces at a magnification of 150,000x. The number of aggregates in a 1 μm × 1 μm area of ​​the obtained images was visually measured. The average value of the number of aggregates measured at the four locations (rounded to the nearest whole number) was calculated. The results are shown in Table 1. (Image acquisition conditions) Magnification: 150,000x Thickness of the sample: 80 nm Acceleration voltage: 200 kV Probe size: 1 nm Image size (pixels): 512 × 512 Observation mode: STEM-DF (dark-field imaging)

[0077] Specifically, first, a scanning transmission electron microscope image is acquired as described above. Next, an elemental mapping image is acquired using an energy-dispersive X-ray spectrometer (JEM-2800 / SDD100GV, manufactured by JEOL Ltd.) attached to the scanning transmission electron microscope, and calcium carbonate is identified in the microscope image by detecting Ca atoms derived from calcium carbonate. Then, the elemental mapping image and a magnified image of the microscope image (a 1 μm × 1 μm area) are compared, and the number of aggregates consisting of three or more calcium carbonate particles is visually measured. The results are shown in Table 1.

[0078] Let's explain this in more detail using Example 1 as an example. Figure 4 shows a scanning transmission electron microscope image of Example 1 (magnification 150,000x), Figure 5 shows an elemental mapping image of Example 1, and Figure 6 shows a magnified view of the scanning transmission electron microscope image (1 μm × 1 μm area). The elemental mapping image in Figure 5 and the magnified view of the scanning transmission electron microscope image (1 μm × 1 μm area) in Figure 6 are visually compared to measure the number of aggregates in the scanning transmission electron microscope image. In Figure 6, aggregates consisting of three or more connected calcium carbonate particles are indicated by circular frames, and the dispersion shows a dispersion containing seven aggregates consisting of three or more connected calcium carbonate particles. In each example, the aggregates consisted of 3 to 12 connected calcium carbonate particles.

[0079] Furthermore, when measuring the number of aggregates, it is preferable to select at least four regions of an image with an arbitrary size of 1 μm × 1 μm, observe the dispersion pattern of calcium carbonate particles in each region, measure the number of aggregates, and calculate the average value of the number of aggregates in the four regions.

[0080] [Damping Characteristics Test] The dynamic shear characteristics of the rubber composition were evaluated using the apparatus shown in Figure 2. Specifically, a two-component adhesive for rubber was applied to predetermined locations (adhesion locations for sample 21) of two blast-treated metal fittings 22 (size 140 mm x 80 mm, thickness 9 mm). Then, the rubber composition of the example or comparative example was sandwiched between the two metal fittings 22 and dried. This was then hot-pressed at 100°C for 10 minutes to produce a sample (size 70 mm x 80 mm, thickness 5 mm) 21. The apparatus was then vibrated in the direction of the arrow, and the dynamic shear characteristics were evaluated based on the load-strain loop curve shown in Figure 3. Specifically, the above apparatus was subjected to vibration excitation simulating a major earthquake (shear strain rate: 200% (200% of sample thickness), frequency (f): 0.33 Hz, measurement temperature: 20°C) using a vibration exciter (Washinomiya Seisakusho Co., Ltd., DYNAMIC SERVO), an input signal oscillator (Yokogawa Electric Corporation, Synthesized Function Generator FC320), and an output signal processor (Ono Sokki Co., Ltd., Portable FFT Analyzer CF-3200). From the analysis of the shear strain value (δ) and load value (Qd) with respect to the excitation time, the equivalent stiffness (Ke) and equivalent damping coefficient (Ce) were determined according to the following equations (1) to (3), and the damping constant (he) was determined from these values. In the following equations, ω = 2πf and W = Keδ 2 / 2, ΔW represents the load-strain loop area (absorbed energy). Equivalent stiffness: Ke (N / mm) = Qd / δ …(1) Equivalent damping coefficient: Ce (kN・s / m) = ΔW / πωδ 2 …(2) Damping constant: he = ΔW / 4πW …(3)

[0081] The attenuation constant in Comparative Example 1 was set to 1.0 (reference), and the exponential values ​​of the attenuation constants in each example and comparative example were calculated and evaluated according to the following criteria. The results are shown in Table 1. (Evaluation Criteria) ◎ (very good) ... Attenuation constant (exponential value) is 1.3 or higher 〇 (good) ... Attenuation constant (exponential value) is greater than 1.0 and less than 1.3 × (poor) ... Attenuation constant (exponential value) is 1.0 or lower

[0082]

[0083] From the results in Table 1 above, it can be seen that the sample of the example satisfies the requirements of the present invention and therefore exhibits excellent decay characteristics. Specifically, it can be seen that the excellent decay characteristics are due to the fact that the number of aggregates, each consisting of three or more calcium carbonate particles, is within a specific range of 5 to 15.

[0084] In contrast, the results in Table 1 above show that the comparative examples do not satisfy the requirements of the present invention and therefore have insufficient damping characteristics. Specifically, Comparative Example 1, which had 25 aggregates of three or more calcium carbonate particles, exhibited inferior damping characteristics. Similarly, Comparative Example 2, which had only one aggregate of three or more calcium carbonate particles, also exhibited inferior damping characteristics.

[0085] Based on the above, it can be seen that the requirements of the present invention are met, namely, a seismic isolation rubber laminate having a rubber layer made of a vulcanized body of a rubber composition for seismic isolation rubber laminates containing (A) at least one of isoprene rubber and butadiene rubber, and the number of aggregates of three or more calcium carbonate particles in any 1 μm × 1 μm square region of a scanning transmission electron microscope image of the rubber layer taken at a magnification of 150,000 is in the range of 5 to 15, and that the damping characteristics are excellent.

[0086] While the above embodiments illustrate specific forms of the present invention, these embodiments are merely illustrative and should not be interpreted restrictively. Various modifications that are obvious to those skilled in the art are intended to fall within the scope of the present invention.

[0087] The seismic isolation rubber laminate of the present invention can exhibit excellent functionality as a seismic isolation rubber laminate used in large structures such as high-rise buildings and bridges.

[0088] 10 Seismic isolation rubber laminate 12 Rubber block 14 Metal plate 16 Rubber layer 18 Upper mounting plate 20 Lower mounting plate

Claims

1. A seismic isolation rubber laminate having a rubber layer made of a vulcanized body of a rubber composition for seismic isolation rubber laminates containing the following components (A) and (B), wherein the number of aggregates of three or more calcium carbonate particles in any 1 μm × 1 μm square region of a scanning transmission electron microscope image of the rubber layer taken at a magnification of 150,000 is in the range of 5 to 15. (A) At least one of isoprene rubber and butadiene rubber (B) Calcium carbonate 2. The seismic isolation rubber laminate according to claim 1, wherein the number of aggregates of three or more calcium carbonate particles is in the range of 6 to 10.

3. The seismic isolation rubber laminate according to claim 1 or 2, wherein the content of component (B) is 25 to 80 parts by mass per 100 parts by mass of component (A).

4. The seismic isolation rubber laminate according to any one of claims 1 to 3, wherein the component (A) above contains isoprene rubber, and the isoprene rubber content is 70% by mass or more of the total amount of rubber components contained in the rubber composition for the seismic isolation rubber laminate.

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