JP2008274158A - Rubber composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rubber composition which is reduced in Mullins effect as well, while maintaining its damping properties. <P>SOLUTION: The rubber composition comprises a rubber component and an alkylene oxide-added aliphatic compound. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rubber composition.

  In recent years, various seismic isolation structures have been developed due to an increase in demand for earthquake-resistant buildings. For example, a seismic isolation structure having a laminated structure of a plurality of highly damped rubber layers and a plurality of hard plate layers plays a role in attenuating the added energy when vibration due to an earthquake or the like is added to a building. Fulfill.

  On the other hand, as rubber materials with high damping characteristics, rubber materials blended with phenol resins, rubber materials blended with coumarone indene resins, rubber materials blended with petroleum resins, rubber materials blended with rosin resins, cyclopentadiene resins And rubber materials containing dicyclopentadiene resin have been proposed (see, for example, Patent Documents 1 to 6).

Also, in general vulcanized rubber, a phenomenon (Mullins effect) in which the elastic modulus decreases due to repeated deformation occurs, the predetermined performance cannot be exhibited, and the design of products using rubber materials may be complicated. is there.
Therefore, a method for reducing the Malins effect by controlling the shape of the vulcanized rubber has been proposed (see, for example, Patent Document 7).
Japanese Patent Laid-Open No. 1-103637 JP-A-4-212844 Japanese Patent Laid-Open No. 10-110062 JP-A-62-230833 JP-A-5-59219 Japanese Unexamined Patent Publication No. 63-22847 JP 2000-283228 A

On the other hand, conventional rubber materials with high damping characteristics, which have been mainly used for seismic isolation rubber and damping materials, have a large decrease in elastic modulus after large deformation due to the Mullins effect. As a result, it is likely that the product design will be complicated, and in the case of seismic isolation rubber, if the aftershock continues after a large earthquake, there is a high possibility that the designed seismic isolation performance will not be achieved. At the same time, it is considered to be extremely important to reduce the Mullins effect, which has not attracted much attention.
Further, the above-described method for reducing the Mullins effect by controlling the shape of the vulcanized rubber is a solution in terms of shape, so that there is a problem that the shape is limited and the versatility is lacking.

As a result of considering these circumstances, the present inventor considered that it is important to reduce the Malins effect by adjusting the blending of the rubber composition.
For this reason, the present inventor has optimized the blending of conventional rubber materials having high damping characteristics as shown in Patent Documents 1 to 6 (for example, types of existing additive components such as resin, carbon, liquid polymer, etc.) And adjustment of the blending amount and the like) to reduce the Malins effect. However, in the conventional rubber composition, it was found that there is a trade-off between the reduction of the Mullins effect and the high damping characteristics, and it is difficult to achieve both.

  The object of the present invention is to solve the above-described conventional problems. That is, an object of the present invention is to provide a rubber composition in which the Malins effect is reduced while maintaining the damping characteristics.

The above object is achieved by the present invention described below. That is, the present invention
<1>
A rubber composition comprising at least an aliphatic compound to which an alkylene oxide is added and a rubber component.

<2>
<5> The rubber composition according to <1>, wherein the aliphatic compound to which the alkylene oxide is added is contained in an amount of 5 to 60 parts by mass per 100 parts by mass of the rubber component.

<3>
The rubber composition according to <1> or <2>, wherein the aliphatic compound to which the alkylene oxide is added is an aliphatic cyclic compound to which an alkylene oxide is added.

<4>
Furthermore, it is a rubber composition of any one of <1>-<3> characterized by containing resin.

<5>
The resin is at least one resin selected from the group consisting of polyester polyol resin, dicyclopentadiene resin, phenol resin, petroleum resin, rosin resin, xylene resin, terpene resin, ketone resin, and modified resins of these resins. It is a rubber composition as described in <4> characterized by being.

<6>
<4> or <5>, wherein the resin is contained in an amount of 5 to 60 parts by mass per 100 parts by mass of the rubber component.

  As described above, according to the present invention, it is possible to provide a rubber composition having a reduced Malins effect while maintaining the damping characteristics.

  The rubber composition of the present invention includes at least an aliphatic compound to which an alkylene oxide is added and a rubber component.

Since the rubber composition of the present invention contains an aliphatic compound to which an alkylene oxide is added, it is possible to reduce the Mullins effect while maintaining the damping characteristics as compared with a rubber composition not containing the material. .
Although the details of the reason why such an effect is obtained are unknown, it is presumed to be due to the following phenomenon. That is, the aliphatic compound to which alkylene oxide is added improves the dispersion of various components added to the rubber component as needed (for example, resin, carbon, etc.), thereby irreversibly changing the internal rubber due to repeated shearing. It is inferred that this is suppressed.

The number of alkylene oxides contained in the aliphatic compound to which alkylene oxide is added is not particularly limited as long as it is one or more per molecule. However, if it is too small, sufficient effects cannot be obtained, and if it is too large, compatibility is obtained. Since it may fall, it is preferable that the number of the alkylene oxide added is 1-500 per molecule, and it is more preferable that it is 1-100.
The structure of the alkylene oxide is not particularly limited, but the alkylene group portion preferably has 1 to 5 carbon atoms, and more preferably has 2 or 3 carbon atoms (that is, ethylene oxide (EO) or propylene oxide (PO)). preferable. Moreover, it is although it does not specifically limit as the number of repeating units, 1-40 are preferable and 1-20 are more preferable.

In addition, the molecular structure of the aliphatic structure portion of the aliphatic compound to which alkylene oxide is added may be appropriately selected from known aliphatic substances, and may be any of linear, branched, and cyclic Good. However, from the viewpoint of reducing the Mullins effect and obtaining higher attenuation characteristics, a compound in which the aliphatic structure portion has a cyclic structure rather than a compound composed only of a linear structure or a branched structure (addition of alkylene oxide) Aliphatic cyclic compound). The size of the ring of the cyclic structure is not particularly limited, but is preferably a 1-membered ring to a 10-membered ring, and more preferably a 1-membered ring to a 5-membered ring.
Furthermore, the aliphatic structure part may contain heteroatoms such as oxygen atom, nitrogen atom and sulfur atom in addition to the carbon atom, and the number of carbon atoms constituting the aliphatic structure part is not particularly limited. However, 2-20 are preferable and 2-6 are more preferable.

  The number average molecular weight Mn of the aliphatic compound to which alkylene oxide is added (hereinafter sometimes simply referred to as “aliphatic compound”) is preferably 100 to 20000, and more preferably 100 to 5000. When the number average molecular weight is within the above range, dispersion into the rubber is facilitated during kneading, and bloom from unvulcanized rubber and vulcanized rubber can be more reliably prevented. Moreover, the said aliphatic compound can use a commercial item.

  The aliphatic compound is preferably contained in an amount of 5 to 60 parts by mass, more preferably 10 to 60 parts by mass, per 100 parts by mass of the rubber component (in the case where there are two or more types). . The addition effect of the said aliphatic compound can be made practical by containing 5-60 mass parts. The content of the aliphatic compound and the number average molecular weight can be measured by a known method.

  The rubber component may be a single rubber component, but a plurality of rubber components may be used in combination. Specifically, natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), isoprene rubber (IR), chloroprene rubber, butyl rubber (IIR), halogenated butyl rubber, ethylene-propylene rubber (EPR, EPDM) ), Fluorine rubber, silicone rubber, urethane rubber and the like. Especially, it is preferable to contain 30 mass% or more of natural rubber in a rubber component from a viewpoint of the mechanical characteristics and workability | operativity of vulcanized rubber.

  The rubber composition of the present invention may contain a compounding agent that is blended and used in a normal rubber composition together with the above components. For example, carbon black, silica, silane coupling agent, sulfur as vulcanizing agent, vulcanization accelerator, vulcanization acceleration aid, various process oils, zinc white, stearic acid, various softeners and resins, wax, aging The various compounding agents generally mix | blended, such as various fillers, such as an inhibitor, petroleum hydrocarbon, rosin, clay, and calcium carbonate, can be mentioned.

  For example, as the vulcanization accelerator, thiurams such as TMTD (tetramethyl disulfide) and dithiocarbamates such as EZ (zinc diethyldithiocarbamate) can be used.

  In combination with these, organic peroxides, quinonedioximes, polyfunctional acrylic monomers (for example, trimethylolethane triacrylate (TMETA), trimethylolpropane triacrylate (TMPTA), dipentaerythritol ether hexaacrylate (DPEHA) ), Pentaerythritol tetraacrylate (DPEHA), dimethylolpropane diacrylate (TMPTA), stearyl acrylate (SA), etc.) and triazine thiol can be used.

  Furthermore, as sulfur-based vulcanizing agents and vulcanization accelerators, powder sulfur, highly dispersible sulfur, insoluble sulfur, etc., sulfur generally used as a vulcanizing agent for rubber, tetramethylthiuram disulfide, tetraethylthiuram disulfide, Tetrabutylthiuram disulfide, tetramethylthiuram monosulfide, thiurams such as dipentamethylenethiuram tetrasulfide, pentamethylenedithiocarbamic acid piperidine salt, pipecolyldithiocarbamic acid pipecoline salt, zinc dimethyldithiocarbamate, zinc diethyldithiocarbamate, dibutyldithiocarbamic acid Zinc, zinc N-ethyl-N-phenyldithiocarbamate, zinc N-pentamethylenedithiocarbamate, zinc dibenzyldithiocarbamate, sodium dimethyldithiocarbamate Diethylcarbamate such as sodium diethyldithiocarbamate, sodium dibutyldithiocarbamate, copper dimethyldithiocarbamate, ferric dimethyldithiocarbamate, tellurium diethyldithiocarbamate, zinc butylxanthate, zinc isopropylxanthate, xanthogenic acid such as sodium isopropylxanthate Salts, N-cyclohexyl-2-benzothiazole sulfenamide, Nt-butyl-2-benzothiazole sulfenamide, N-oxydiethylene-2-benzothiazole sulfenamide, N, N-diisopropyl-2-benzo List sulfenamides such as thiazole sulfenamide, and thiazoles such as 2-mercaptobenzothiazole and dibenzothiazyl disulfide. It can be. These can be used in combination. The amount used is preferably 0.5 to 10.0 parts by mass and more preferably 1.0 to 6.0 parts by mass with respect to 100 parts by mass of the rubber component.

  Moreover, it is preferable that resin is contained in the rubber composition of this invention. The resin is at least one resin selected from the group consisting of polyester polyol resins, cyclopentadiene resins, phenol resins, petroleum resins, rosin resins, xylene resins, terpene resins, ketone resins, and modified resins of these resins. It is preferable. By using these resins together with an aliphatic compound to which an alkylene oxide is added, it becomes easier to achieve both a high attenuation characteristic and a reduction of the Malins effect at a higher level.

  In total, these resins are preferably contained in an amount of 5 to 60 parts by mass, more preferably 5 to 40 parts by mass, per 100 parts by mass of the rubber component. By containing 5 to 60 parts by mass, the Mullins effect can be reduced while maintaining workability and mechanical properties.

  Examples of the carbon black to be used include standard varieties such as SAF, ISAF, HAF, FEF, GPF, SRF (rubber furnace) and MT carbon black (pyrolytic carbon). The amount is preferably 20 to 100 parts by mass, more preferably 25 to 80 parts by mass with respect to 100 parts by mass of the rubber component. In addition to carbon black, a plasticizer such as dioctyl sebacate may be added.

  A known anti-aging agent can also be selected and used for the anti-aging agent. For example, N-phenyl-N ′-(1,3-dimethylbutyl) -p-phenylenediamine (6C), N-phenyl-N′-isopropyl-p-phenylenediamine (3C), 2,2,4-trimethyl -1,2-dihydroquinoline polymer (RD) and the like. These can use about 0.5-5 weight part with respect to 100 weight part of rubber components.

  Examples of petroleum hydrocarbons include C9 aromatic unsaturated hydrocarbons and C5 aliphatic unsaturated hydrocarbons. As C9 type aromatic unsaturated hydrocarbon, vinyl such as α-methylstyrene, o-vinyltoluene, m-vinyltoluene, p-vinyltoluene and the like obtained by thermal decomposition of naphtha and contained in the C9 fraction Examples thereof include substituted aromatic hydrocarbons.

  Examples of the C5 aliphatic unsaturated hydrocarbon include pentene- (1), pentene- (2), 2-methylbutene- (1), 3-methylbutene-, which are contained in the C5 fraction obtained by thermal decomposition of naphtha. (1), olefinic hydrocarbons such as 2-methylbutene- (2), 2-methylbutadiene- (1,3), pentadiene- (1,2), pentadiene- (1,3), 3-methylbutadiene -Diolefin type hydrocarbons such as (1,2).

  The rubber composition of the present invention as described above can be produced by kneading the above-described components using a kneading apparatus such as a Banbury mixer, a roll or a kneader that is usually used in the rubber industry.

  The rubber composition of the present invention can be molded into various shapes such as a sheet, a rectangular parallelepiped, a rectangle, a polygon, a cylinder, and a sphere. It is also possible to use it by forming it into a sheet and punching it out. Depending on the purpose of use, it may be irregularly shaped. In particular, in the case of a rubber composition for a seismic isolation structure, it is generally in the form of a sheet.

  A plurality of rubber compositions (rubber sheets) molded into a sheet shape are laminated to obtain a seismic isolation structure with a rubber laminate.

  The evaluation of the Mullins effect in the rubber laminate used for the seismic isolation structure can be performed by the retention rate of the shear elastic modulus after large deformation.

  The rubber composition of the present invention and the rubber laminate obtained from the rubber composition are effectively used for seismic isolation structures mainly in support parts such as high-rise buildings, houses, road bridges and bridges, It can also be used for applications such as vibration isolation devices in experimental devices. Moreover, it is applicable also to buffer materials, such as a cable-stayed bridge cable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited to these Examples.

[Examples 1 to 16 and Comparative Examples 1 to 6]
The components shown in Tables 1 to 3 below were kneaded with a Banbury mixer to produce rubber compositions. The obtained rubber composition was rolled to a thickness of 2 mm using a rubber rolling roll to produce a rubber sheet.
In Tables 1 to 3, kneading stage A represents a step of kneading a rubber component excluding a vulcanizing agent and a vulcanization accelerator, and kneading stage B represents a rubber composition obtained in kneading stage A. It means a step of kneading a vulcanizing agent or a vulcanization accelerator.

The following products were used as the components of the formulations shown in Tables 1 to 3 above.
・ Rubber component, natural rubber; RSS # 4 is used. ・ Rubber component, BR (butadiene rubber); Asahi Kasei diene NF35R is used. ・ Inorganic filler, carbon black; Asahi # 80-N (Asahi Carbon Co., Ltd.) used ・ Hardened fatty acid; FA-KR (Nippon Yushi Co., Ltd.) used ・ Zinc Hana as “vulcanization accelerator”; No. 3 Zinc Hana (Shiramizu Chemical Co., Ltd.) Used) Petroleum hydrocarbons; Suntite S (made by Seiko Chemical Co., Ltd.) was used. Anti-aging agent 6C; Antigene 6C (produced by Sumitomo Chemical Co., Ltd.) was used.

・ Polyester polyol resin; using Zeofine (manufactured by Nippon Zeon Co., Ltd.) ・ cyclopentadiene resin; using Quinton 1325 (manufactured by Nippon Zeon Co., Ltd.) ・ Phenolic resin: Sumilite Resin 217 (manufactured by Sumitomo Bakelite Co., Ltd.) Used: C9 petroleum resin: Nisseki Neopolymer E130 (manufactured by Shin Nippon Petrochemical Co., Ltd.) used. Rosin resin: Hyrosin (manufactured by Taisha Matsusei Oil Co., Ltd.) used. C5 / C9 petroleum resin: Quinton D100 (Made by Nippon Zeon Co., Ltd.)

EO-added aliphatic cyclic compound: Rheodor TW-S106V (manufactured by Kao Corporation, see compound 1 below) EO-added aliphatic compound: Softanol D50 (manufactured by Nippon Shokubai Co., Ltd., see compound 2 below) Use EO addition aliphatic compound; Rheodor 460V (manufactured by Kao Corporation, see the following compound 3) Use EO addition aliphatic compound; Softanol 500 (made by Nippon Shokubai Co., Ltd., see the following compound 4) use

・ Heavy aroma oil; Dynana process oil AH-58 (made by Idemitsu Kosan Co., Ltd.) ・ Zinc flower mixed sulfur that is “crosslinking agent”; Z sulfur (made by Tsurumi Chemical) is used ・ It is an “accelerator” Accelerator CZ: Noxeller CZ (Ouchi Shinsei Chemical Co., Ltd.) used

[Evaluation]
With respect to the rubber sheets of Examples and Comparative Examples, the elongation at break (Eb), tensile strength (Tb), shear modulus (G), Mullins effect and damping constant (Heq) were measured as follows. The shear elastic modulus (G) and the Mullins effect were obtained by carrying out shear measurement. The results are shown in Tables 4 to 6 below.

(1) Elongation at break (Eb):
The elongation at break was determined according to JIS K 6301.

(2) Tensile strength (Tb):
The tensile strength was determined according to JIS K 6301.

(3) Shear elastic modulus (G) and equivalent damping coefficient (Heq):
[Preparation of shear elastic modulus measurement sample]
One rectangular rubber sheet was produced by punching the rubber sheet into a 25 mm × 25 mm square, and this was sandwiched between two iron plates of 25 mm × 60 mm × 2.3 mm in thickness. That is, as shown in FIG. A rectangular rubber sheet 20 was sandwiched between two iron plates 22 coated with an adhesive so as to have a cross-sectional crank shape. In this way, vulcanization was performed in a state where the iron plate 22 and the surface of the rubber sheet 20 in contact with the iron plate 22 were bonded, and the iron plate 22 and the rubber sheet 20 surface were bonded. As a result, a sample having the shape shown in FIG.

[Measurement of shear modulus]
The sample was placed in a spring stiffness / loss energy measuring device (manufactured by Kakinomiya Seisakusho, model: EFH-26-8-10). The above-mentioned two steel plates (FIG. 2B) were subjected to shear force by changing the shear rate in the order of the following 1st and 2nd at a frequency of 0.2 Hz on the outside and inside of the rubber sheet. At the same shear rate, a shear force was applied three times.

1st: 50% → 100% → 200% → 300%
2nd: 50%-100%->200%-> 300%

Then, at each shear rate, G and Heq were calculated from the measured value when the 1st shear force was applied (third time) and the measured value when the 2nd shear force was applied (third time).
“G” means a shear elastic modulus (sometimes referred to as equivalent spring stiffness). “Heq” is an equivalent attenuation coefficient and is an index of the magnitude of hysteresis loss. Further, the Malin's effect was evaluated by a ratio (G2nd / G1st) of 1st G and 2nd G in the same strain.

  From the results shown in Tables 4 to 6, the rubber sheet made of the rubber composition of the example is a rubber made of the rubber composition of the comparative example having the same blending composition except that it does not contain an aliphatic compound to which an alkylene oxide is added. Compared to the sheet, it has been found that the Mullins effect is reduced while maintaining the damping characteristics, or that the damping characteristics are improved and the Mullins effect is also reduced.

It is the schematic which shows the structure of the sample for shear modulus measurement of a rubber composition, (A) shows the state which pinches | interposes a square rubber sheet, (B) shows the state which adhere | attached the square rubber sheet.

Explanation of symbols

20 ... Square rubber sheet 22 ... Iron plate

Claims (6)

  A rubber composition comprising at least an aliphatic compound to which an alkylene oxide is added and a rubber component.   2. The rubber composition according to claim 1, wherein the aliphatic compound to which the alkylene oxide is added is contained in an amount of 5 to 60 parts by mass per 100 parts by mass of the rubber component.   The rubber composition according to claim 1 or 2, wherein the aliphatic compound to which the alkylene oxide is added is an aliphatic cyclic compound to which an alkylene oxide is added.   Furthermore, resin is contained, The rubber composition of any one of Claims 1-3 characterized by the above-mentioned.   The resin is at least one resin selected from the group consisting of polyester polyol resin, dicyclopentadiene resin, phenol resin, petroleum resin, rosin resin, xylene resin, terpene resin, ketone resin, and modified resins of these resins. The rubber composition according to claim 4, wherein the rubber composition is present.   The rubber composition according to claim 4 or 5, wherein the resin is contained in an amount of 5 to 60 parts by mass per 100 parts by mass of the rubber component.

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