JP2005320376A - Rubber composition for seismic isolation laminate and seismic isolation laminate using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition for a seismic isolation support structure, which can be vulcanized for a long period of time with suppressed reversion and can follow a large horizontal deformation while it retains a stress at 100% shear deformation as an index of seismic isolation performance and to provide an seismic isolation laminate using such a rubber composition. <P>SOLUTION: The rubber composition is obtained by compounding 99 to 90 pts.wt. diene rubber as a base material with 1 to 10 pts.wt. liquid polyisoprene. The liquid polyisoprene is desirably a polyisoprene/maleic anhydride adduct or a polyisoprene/monomethyl maleate adduct. Desirably, the above rubber composition further contains 0.5 to 10 pts.wt. metal α,β-unsaturated carboxylate, especially zinc methacrylate for the purpose of effectively suppressing reversion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rubber composition for a laminated body used for a base-isolated bearing structure such as a building or a bridge, and a base-isolated laminated body using the rubber composition.

  In recent years, in order to prevent damage to buildings, bridges, and other structures due to earthquakes, seismic isolation bearing structures with laminated bodies in which rubber layers and metal layers are alternately laminated in the vertical direction and bonded to each other are becoming widespread. is there. This seismic isolation structure reduces the damage to structures caused by earthquakes by making the vibration period transmitted to the structure longer than the earthquake period (so-called seismic isolation function) and damping the vibration (so-called damping function). .

  The seismic isolation function of the base-isolated bearing structure generally uses the spring characteristics of the rubber layer. However, the damping function is demonstrated by the damping function of the rubber layer itself (high damping rubber). It may be exhibited by installing a damper (oil damper, friction damper, lead damper, etc.) having a damping function. When using high-damping rubber, it is not necessary to install a separate damper, so the cost of the base-isolated bearing structure is low. However, due to the temperature dependence of the rubber and creep, the seismic isolation function is used when installing a damper. It is inferior compared. Patent Documents 1 and 2 disclose high-damping rubber compositions for rubber laminates.

On the other hand, if a separate damper is installed, the cost will be higher by the amount of the damper installed, but the damping function is higher than when using high-damping rubber, and a highly reliable seismic isolation structure. It is possible to obtain Patent Documents 3 and 4 disclose rubber compositions that can be used for a damper combined type seismic isolation laminate.
Japanese Patent Laid-Open No. 11-80424 JP-A-11-263879 Japanese Patent Laid-Open No. 11-5873 JP-A-11-34218

  Here, in addition to the above-mentioned seismic isolation function and damping function, it is also considered important for the seismic isolation laminate to have shear fracture resistance, that is, followability to horizontal deformation. This is because not being able to return the structure to its original position if it cannot withstand the large horizontal deformation caused by a large earthquake, it may cause the structure to collapse. However, the required level of base isolation performance for base isolation bearing structures has been increasing year by year. Conventionally, the shear fracture elongation of the bearing rubber for bridges in particular has been required to be about 300%, but recently it has been required to be 350% or more. The value of 350% or more in this seismic isolation laminate corresponds to 420% or more in the shear fracture elongation of a test piece obtained by vulcanizing and bonding a rubber piece of 25 mm width × 25 mm length × 5 mm thickness between two steel plates. This is clear from past data.

  Here, 100% shear stress (MPa) is an index of the ability to mitigate earthquakes by lengthening the natural period of structures such as buildings, but as rubber, the higher the numerical value, the smaller the shear fracture elongation (%). It becomes difficult to follow a large displacement during an earthquake. For this reason, in particular, rubber bearings for bridges and the like often have 100% shear stress (MPa) in the range of 0.8 to 1.4, and the shear fracture elongation is 350% or more, which is the level currently required. (420% or more for the test piece) is desirable. However, for example, in the rubber compositions of Patent Documents 3 and 4, it has been difficult to satisfy the recent seismic isolation performance required for the seismic isolation bearing structure.

  On the other hand, some seismic isolation laminates have a diameter or a side exceeding 1 m, and are extremely large and thick as rubber products. When vulcanizing by heating and pressurizing such a large thick product, in order to sufficiently vulcanize the middle part of the outer diameter and inner diameter away from the heat source, the heating time is lengthened and the heat is heated to the middle part. I need to tell. However, if the heating time is lengthened, the portion near the heat source is excessively heated, the rubber in this portion is deteriorated, and the adhesive force between the rubber layer and the metal layer is lowered. In particular, a compounded rubber in which sulfur is kneaded with natural rubber generally causes reversion of vulcanization when heated for a long time, and the quality is likely to deteriorate.

  As a method to suppress vulcanization reversion, the amount of sulfur is reduced, but if the amount of sulfur is reduced, the adhesive strength between the rubber layer and the metal layer decreases, and the structure is subjected to weight during an earthquake. When a large deformation occurs in the horizontal direction, the adhesive interface between the rubber layer and the metal layer peels off, and the function of the seismic isolation bearing structure may be impaired.

  The present invention can suppress a deterioration in quality due to reversion even after vulcanization for a long time, and can maintain a stress at the time of 100% shear deformation, which is an index of the seismic isolation function, while allowing large deformation in the horizontal direction. It is an object of the present invention to provide a rubber composition for a seismic isolation bearing structure that can also follow, and a seismic isolation laminate using such a rubber composition.

  The present invention relates to a rubber composition in which a predetermined amount of liquid polyisoprene is blended with a diene base rubber. Moreover, this invention relates to the seismic isolation laminated body comprised from such a rubber composition.

  Specifically, the present invention relates to a rubber composition for a seismic isolation laminate, wherein 1 to 10 parts by weight of liquid polyisoprene is blended with 99 to 90 parts by weight of a diene rubber (claim 1). The present invention also relates to a seismic isolation laminate (Claim 7) comprising a laminate in which rubber layers and metal layers made of such a rubber composition for a seismic isolation laminate are alternately laminated in the vertical direction.

  In the rubber composition, molecular cleavage and recombination occur simultaneously during vulcanization for a long time. However, if the ratio of molecular cleavage is high, the vulcanization return increases and the quality deteriorates. In the rubber composition of the present invention, by blending liquid polyisoprene with a diene rubber, molecular breakage is less likely to occur, or molecular recombination is likely to occur, so that reversion is less likely to occur. Thereby, the composition of the present invention has a 100% shear stress (MPa) of 0.8 to 1. in a test piece obtained by vulcanizing and bonding a rubber piece of 25 mm width × 25 mm length × 5 mm thickness between two steel plates. 4 shows a high shear fracture elongation of 420% or more.

  If the amount of liquid polyisoprene is less than 1 part by weight, the effect of suppressing vulcanization return cannot be expected. If the amount of liquid polyisoprene exceeds 10 parts by weight, not only the effect of suppressing vulcanization return is saturated but also the shear fracture elongation (%) decreases.

  When a functional group is present in liquid polyisoprene, recombination of the cleaved molecule is likely to occur, and the regularity of the molecular structure is more disturbed to suppress the stretched crystallinity. As shown in FIG. The strain is shifted to the higher strain side, increasing the shear failure elongation (%) at the same shear stress. Therefore, the liquid polyisoprene used in the rubber composition of the present invention is preferably a maleic anhydride adduct or a maleic acid monomethyl ester adduct having a functional group (Claim 2).

  The rubber composition of the present invention may further contain an α, β unsaturated carboxylic acid metal salt, or an α, β unsaturated carboxylic acid and a metal compound as a co-crosslinking agent with oil sulfur. The α, β unsaturated carboxylic acid metal salt, or the α, β unsaturated carboxylic acid and the metal compound can be expected to have an effect of improving adhesion to the metal in addition to the effect of suppressing vulcanization and shear fracture elongation. In particular, α, β unsaturated carboxylic acids include methacrylic acid, acrylic acid, maleic acid, fumaric acid, itaconic acid, etc., and methacrylic acid and acrylic acid are excellent in terms of dispersibility and co-crosslinking property of the base rubber. preferable. Examples of the metal of the α, β-unsaturated carboxylic acid metal salt include zinc, nickel, magnesium, sodium, potassium, and the like, and it is preferable to use zinc in terms of excellent co-crosslinking properties. When a metal methacrylate is contained, the above effect cannot be expected if the amount is less than 0.5 parts by weight, and if the amount exceeds 10 parts by weight, the shear fracture elongation (%) decreases. It is preferable that the amount is not more than parts by weight. In addition, as the α, β unsaturated carboxylic acid, methacrylic acid or acrylic acid may be included together with the zinc compound (Claim 6).

  In the rubber composition of the present invention, since blending 1 to 10 parts by weight of liquid polyisoprene with 99 to 90 parts by weight of a diene rubber makes it difficult for the quality to deteriorate due to reversion, there is no need to reduce the amount of sulfur. The adhesive interface between the rubber layer and the metal layer is difficult to peel off. Moreover, it is possible to follow a large horizontal deformation that occurs during an earthquake while maintaining the stress during 100% shear deformation, which is an index of the seismic isolation function. By using the rubber composition of the present invention for the seismic isolation laminate, the seismic isolation performance is enhanced as compared with the conventional seismic isolation laminate, and the collapse of the structure due to the earthquake can be more effectively prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. However, the present invention is not limited to the following unless it exceeds the gist.

  FIG. 2 shows a cross-sectional view of the seismic isolation laminate according to one embodiment of the present invention. The lead damper combined type seismic isolation laminate 1 includes a laminate 4 in which a plurality of rubber layers 2 and metal layers 3 are alternately laminated in the vertical direction. The rubber layer 2 and the metal layer 3 are vulcanized and bonded. The planar shape of the rubber layer 2 and the metal layer 3 is circular. The laminated body 4 includes an outer rubber 5 on the outer periphery thereof. The rubber layer 2 and the outer rubber 5 are integrated by rubber flow when the laminated body 4 is vulcanized. Although various metal materials can be applied to the metal layer 3, steel is generally used. On the top and bottom of the laminate 4, flange portions 6a and 6b made of steel or the like are provided. The flange portions 6a and 6b and the rubber layer 2 in contact with the flange portions 6a and 6b are vulcanized and bonded. A lead damper 7 is installed at the center of the seismic isolation laminate so as to penetrate the laminate vertically. The upper flange portion 6a is connected to the foundation ground by appropriate connection means (not shown), and the upper flange portion 6b is connected to a structure such as a building or a bridge by appropriate connection means (not shown).

  FIG. 3 shows a cross-sectional view of a seismic isolation laminate according to another embodiment of the present invention. The basic structure of the non-damper combined seismic isolation layer 11 is the same as that of the lead damper combined type seismic isolation layer 1 shown in FIG. 2 except that the lead damper 7 is not provided. 2 has a center hole 17 so as to penetrate the laminate 14 up and down, and the center portion is hollow, but does not have such a center hole 17. The non-damper combined seismic isolation laminate shown in FIG. 4 is also included in the seismic isolation laminate according to the present invention.

  For the rubber layer 2, the rubber composition of the present invention is used. The unvulcanized rubber used as the base material of the rubber composition of the present invention is natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene butadiene rubber (SBR), chloroprene rubber (CR), acrylonitrile butadiene. A diene rubber such as rubber (NBR) may be used, but natural rubber is suitable in terms of excellent fracture characteristics.

Furthermore, the rubber composition of the present invention is appropriately mixed with chemicals such as a vulcanizing agent, a vulcanization accelerator, a vulcanization retarder, a vulcanization acceleration aid, an anti-aging agent, a reinforcing agent, a softening agent, and a filler. You can also.
(Manufacture of rubber composition)

  95 parts by weight of natural rubber (SMR CV60) was put into a 1.5 liter BR type Banbury and masticated. Further, 5 parts by weight of liquid polyisoprene (1) (Kuraray LIR-30: monomethyl ester adduct of polyisoprene), 48 parts by weight of HAF carbon black (Tokai Carbon Seast 3) as a reinforcing agent, and vulcanization acceleration 3 parts by weight of zinc oxide (zinc oxide manufactured by Sakai Chemical) as an auxiliary agent, 1 part by weight of stearic acid (stearic acid slag manufactured by NOF Corporation) as a processing aid, and N-phenyl-N-isopropyl-p-phenylene as an anti-aging agent 1 part by weight of diamine, 1.2 parts by weight of sulfur (oil sulfur manufactured by Hosoi Chemical Co., Ltd.) and N-cyclohexyl-2-benzothiazole sulfenamide (CBS: Ouchi Shinsei Chemical Industry) as a sulfenamide-based vulcanization accelerator Product name "Noxeller CZ-G") 0.8 parts by weight, tetrakis (2-ethylhexyl) as thiuram vulcanization accelerator Ulam disulfide (TOT: Ouchi Shinko Chemical Industry Co., Ltd., trade name "Nocceler TOT-N") were charged and 0.5 parts by weight, was drained and kneaded for 5 minutes. The discharged rubber composition was kneaded with an open roll and sheeted to form a sheet having a thickness of 5.0 mm. This unvulcanized rubber sheet was used for preparing a test piece for physical property testing. The vulcanization temperature and time were set to 150 ° C. × 300 min from the point that the seismic isolation laminate was large and heat was not easily transmitted during vulcanization, requiring a long time.

  Instead of 5 parts by weight of liquid polyisoprene (1), the same as Example 1 except that 5 parts by weight of liquid polyisoprene (2) (Kuraray LIR-403: polyisoprene maleic anhydride adduct) was used. is there.

  The same as Example 2, except that 1 part by weight of liquid polyisoprene (2) was used.

  The same as Example 2 except that 10 parts by weight of liquid polyisoprene (2) was used.

  Instead of 5 parts by weight of liquid polyisoprene (1), the same as Example 1 except that 5 parts by weight of liquid polyisoprene (3) (Kuraray LIR-410: maleic anhydride adduct of polyisoprene) was used. is there.

  Example 2 is the same as Example 2 except that 2 parts by weight of zinc methacrylate is further added as a co-crosslinking agent.

  The same as Example 6, except that 0.5 parts by weight of zinc methacrylate was used.

  The same as Examples 6 and 7, except that 5 parts by weight of zinc methacrylate was used.

  The same as Examples 6 to 8, except that 10 parts by weight of zinc methacrylate was used.

  Example 2 is the same as Example 2 except that 2 parts by weight of magnesium acrylate is added as a co-crosslinking agent.

  Example 2 is the same as Example 2 except that 1.0 part by weight of methacrylic acid and 1.0 part by weight of zinc sulfide are blended as a co-crosslinking agent.

[Comparative Example 1]
Example 1 is the same as Example 1 except that the natural rubber is 100 parts by weight and the liquid polyisoprene (1) is not blended.

[Comparative Example 2]
The same as Comparative Example 1 except that the HAF carbon black was 55 parts by weight.

[Comparative Example 3]
The same as Example 1, except that the natural rubber was 80 parts by weight and the liquid polyisoprene (2) was 20 parts by weight.

  Table 1 shows a list of raw material compositions and physical properties of the rubber compositions of Examples and Comparative Examples.

(Reduction effect of vulcanization return)
At the time of vulcanization (conditions: 150 ° C., 300 min) of the rubber compositions of all Examples and Comparative Examples, the maximum torque of the rheometer and the torque at the end of vulcanization were measured to obtain a torque difference. This torque difference = maximum torque−torque at the end of vulcanization (dNm: Deci Newton meter) is an index of vulcanization return of the rubber composition. The smaller the torque difference, the smaller the vulcanization return and the greater the torque difference. It shows that vulcanization reversion is so large. The torque difference of each rubber composition is as described in Table 1.

  In Comparative Examples 1 and 2 in which liquid polyisoprene was not blended, the torque differences were 1.5 and 1.7, respectively, but the torque differences in the examples were all 1 or less. In particular, Example 4 and Examples 6 to 8 were rubber compositions having a torque difference of 0 and very low reversion.

  From the comparison of Examples 1, 2 and 5, from the fact that the same 5 parts by weight is blended with 95 parts by weight of natural rubber, the effect of suppressing the vulcanization return is higher than that of liquid polyisoprene (1) and liquid polyisoprene (2). Although 3) was high, the 100% shear stress (MPa) and the shear fracture elongation (%) of the rubber composition were equivalent. In addition, it was considered from the comparison between Examples 2 to 4 and Comparative Example 3 that the higher the amount of liquid polyisoprene (2), the higher the effect of suppressing vulcanization return, but the amount was increased to 20 parts by weight. As a result, the shear fracture elongation (%) was lowered, so that the liquid polyisoprene (2) was preferably 1 to 10 parts by weight.

  From the comparison between Example 2 and Examples 6 to 9, it was confirmed that by adding 0.5 parts by weight or more of zinc methacrylate, the torque difference became 0 and the reversion was effectively suppressed. However, since the shear fracture elongation (%) tended to decrease as the amount of zinc methacrylate added increased, the amount of zinc methacrylate added is preferably 10 parts by weight or less.

(Preparation of specimens used for material shear test)
Rubber compositions of Examples and Comparative Examples Sheets of the rubber compositions of Examples 1 to 9 and Comparative Examples 1 to 3 have a thickness of 5 mm, a length of 25.0 mm and a width of 25. Punched into a 0 mm block of rubber. As a metal plate indicated by reference numerals 9a and 9b, a steel plate having a thickness of 2.6 mm was cut into a length of 25.0 mm and a width of 60.0 mm. The adhesive surfaces of the metal plates 9a and 9b were degreased by sandblasting, and immediately after that, a vulcanized adhesive having a chlorine content of 15% by weight was applied and dried. Then, as shown in FIG. 4, metal plates 9a and 9b were attached to the upper and lower surfaces of the rubber piece 8, and vulcanized under conditions of 150 ° C. × 300 min to obtain a test piece used for the material shear test.

(Shear fracture test)
The upper metal plate 9a of each test piece is fixed, the lower metal plate 9b is pulled to the right in FIG. 2 at a speed of 50 mm / min, and the stress (100% stress: MPa). Further, after the stress measurement, the test piece was pulled at the same speed until it broke, and the displacement (mm) of the lower metal plate 9b at the time of breakage was measured. The ratio (%) of this displacement to 5 mm which is the thickness of the rubber piece 8 was defined as shear fracture elongation. The measurement results of 100% shear stress and shear fracture elongation for each test piece are as shown in Table 1.

  The 100% shear stress (MPa), which is an index of the ability to ease the seismic period of the earthquake by lengthening it, can maintain the level of 0.8 to 1.4 MPa that has been conventionally used in both Examples and Comparative Examples. You can see that

  On the other hand, as for the shear fracture elongation (%), the comparative example is 390 to 410%, while the example is 420 to 470%, and the numerical value of elongation in the example is improved by 50% or more. I understand that.

  Since a large displacement at the time of an earthquake occurs in the horizontal direction, the shear fracture elongation by the test piece is an indicator of the horizontal displacement response force of the seismic isolation laminate shown in FIGS. The base-isolated laminate having the structure shown in FIG. 3 using the rubber composition of the example has a horizontal displacement of 350% that is 50% or more larger than the base-isolated laminate having the same structure using the rubber composition of the comparative example. It was not destroyed until. By providing such a base-isolated laminated body, it becomes possible to improve the safety, reliability, and recoverability of the damper type base-isolated support beam structure.

  Thus, the rubber composition of the present example has higher shear fracture performance than the rubber composition of the comparative example, and is larger when used in a seismic isolation laminate as shown in FIGS. Can withstand horizontal displacement. The seismic isolation laminate using the rubber composition of the present embodiment can be used for various types of base isolation bearing structures, and is particularly preferably used for the damper combined type base isolation bearing structure shown in FIG. As a result, it is possible to exhibit higher safety, reliability, and recoverability compared to conventional products.

It is a conceptual diagram showing the improvement effect of the shear fracture elongation of the rubber composition of this invention. It is sectional drawing of the damper combined use type seismic isolation laminated body which concerns on one Embodiment of this invention. It is sectional drawing of the damper non-combination type seismic isolation laminated body which concerns on another embodiment of this invention. It is sectional drawing of the damper non-combination-type seismic isolation laminated body which concerns on another embodiment of this invention. It is the perspective view which showed the test piece used for a shear fracture test.

Explanation of symbols

1: Damper combined type seismic isolation laminate 11: Damper non-use type seismic isolation laminate with center hole 21: Damper non-use type seismic isolation laminate without center hole 2, 12, 22: Rubber layer 3, 13 , 23: Metal layer 4, 14, 24: Laminate 5, 15, 25: Outer rubber 6a, 16a, 26a: Lower flange 6b, 16b, 26b: Upper flange 7: Lead damper 17: Center hole 8: Rubber Piece 9a: Upper metal plate 9b: Lower metal plate

Claims (7)

  A rubber composition for a base-isolated laminate, comprising 99 to 90 parts by weight of a diene rubber and 1 to 10 parts by weight of liquid polyisoprene.   The rubber composition for a base-isolated laminate according to claim 1, wherein the liquid polyisoprene is a maleic anhydride adduct or a maleic acid monomethyl ester adduct.   The rubber composition for a seismic isolation laminate according to claim 1 or 2, further comprising an α, β unsaturated carboxylic acid metal salt, or an α, β unsaturated carboxylic acid and a metal compound.   The rubber composition for a seismic isolation laminate according to claim 3, wherein the α, β unsaturated carboxylic acid metal salt is zinc methacrylate or zinc acrylate.   The rubber composition for a seismic isolation laminate according to claim 3, wherein the content of the α, β unsaturated carboxylic acid metal salt is 0.5 parts by weight or more and 10 parts by weight or less.   The rubber composition for a base-isolated laminate according to claim 3, wherein the α, β unsaturated carboxylic acid is methacrylic acid or acrylic acid.   A base-isolated laminate comprising a laminate in which rubber layers and metal layers made of the rubber composition for a base-isolated laminate according to claim 1 are alternately laminated in the vertical direction.

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