JP3441678B2 - Ultra-low hardness rubber material for vibration isolation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultra-low hardness anti-vibration rubber material used for anti-vibration of precision equipment such as audio equipment, computer-related equipment and game equipment.

[0002]

2. Description of the Related Art In recent years, audio equipment, computer-related equipment, game equipment, and the like are often equipped with an optical disk device. This optical disk device is vulnerable to vibrations, and is therefore equipped with a vibration-proof, vibration-damping or shock-absorbing material.

Such a vibration-proof material generally has a low hardness, a small compression set (c-set), a large loss tangent (tan-δ), and a temperature dependency (for example, 0 to 80 ° C.). It is desirable that the change in Young's modulus in the range of 1) is small. Also,
The raw material composition used for the production of these vibration isolating materials must be easy to produce (in particular, have good kneading properties) and excellent in processability.

[0004] Generally, such vibration damping materials are manufactured from thermoplastic or thermosetting compositions. An anti-vibration material manufactured from a thermoplastic composition is disclosed in, for example, JP-A-9-23.
Although described in JP-A No. 5477 and JP-A No. 9-263702, these materials have the drawbacks that they have a large compression set and a large temperature dependence.

On the other hand, as a vibration-proof material produced from a thermosetting composition, those containing butyl rubber as a main component (JP-A-9-3278 and JP-A-9-71700) are known. However, this anti-vibration material has a limit in reducing the hardness. That is, in order to obtain a low-hardness anti-vibration material, it is necessary to add a large amount of an extender component such as process oil to the raw material composition, but if so, the kneading property of the raw material composition deteriorates (raw material composition). The composition adheres to the roll),
In addition, the process oil bleeds.
Further, even if a low-vibration damping material is produced by using a special method, there is a problem that the compression set is large.

Further, as a vibration damping material produced from a thermosetting composition, a material containing polynorbornene as a main component
(Actual No. 63-72795, No. 7-52435)
Although they are also known, they have a drawback that they have poor temperature characteristics. Further, the kneading property and bleeding of the raw material composition are not satisfactory.

Further, Japanese Patent Publication No. 60-43865 discloses a vibration damping material obtained by pressure molding a composition comprising a silicone rubber, a partially crosslinked butyl rubber, an extending oil and a reinforcing filler. However, the damping material described in this document is a spring type hardness tester with a hardness of 18 to 25.5, and is aimed at a durometer hardness of A15 or less according to JIS K6253 which is a target of the present invention. Not a thing.

Further, in Japanese Patent Laid-Open No. 7-324167,
A low molecular weight material-holding medium material composite is prepared by previously mixing a low molecular weight material such as process oil and a medium material such as a thermoplastic polymer organic material, and then the low molecular weight material-holding medium material composite and natural A vibration damping material obtained by mixing a polymer material such as rubber and vulcanizing and curing it in the presence of a curing agent such as sulfur is described. This damping material achieves a low hardness of 15 asker C hardness (25 ° C.), which is not sufficient in terms of compression set characteristics.

[0009]

As described above, the anti-vibration material used for audio equipment, computer-related equipment, game equipment, etc. has low hardness and small compression set.
It is desirable that the loss tangent is large and the temperature dependence is small. In addition, the raw material composition used for manufacturing these vibration damping materials must be easy to manufacture and excellent in processability. However, no conventional vibration damping material satisfies all of these requirements. Therefore, the present inventors sought to obtain a vibration damping material that meets all of these requirements.

[0010]

Means for Solving the Problems As a result of intensive studies to solve the above problems, the present inventors have found that partially crosslinked butyl rubber has good kneading properties even when filled with a large amount of oil, and retains oil. It was found that it is highly effective and can suppress oil bleed. Further, when a partially crosslinked butyl rubber containing such a large amount of oil is crosslinked and cured, it is possible to obtain an antivibration material having extremely low hardness, small compression set, large loss tangent, and small temperature dependence. I found it.

That is, the present invention relates to a partially crosslinked butyl rubber 10
The present invention provides a rubber composition obtained by mixing 50 to 200 parts by weight of an extender component with 0 part by weight.
The rubber composition of the present invention may further contain a filler, a vulcanizing agent, a processability-improving polymer material and / or other compounding agents for rubber. Further, the present invention is obtained by crosslinking and curing the above rubber composition,
Durometer hardness according to 3 is A15 or less, preferably A
Asker C hardness is 10 or less, Asker C hardness is 10 or more, preferably 15 or more, compression set (70 ° C. × 24 hours) according to JIS K6262 is 20% or less, and loss tangent
The present invention provides a vibration-proof rubber material having a (25 ° C., 30 Hz) of 0.1 or more.

[0012]

The present invention will be described in more detail below. The partially cross-linked butyl rubber used in the present invention is, for example, a butyl rubber obtained by adding a vinyl aromatic compound (styrene, divinylbenzene, etc.) and an organic peroxide to butyl rubber as described in JP-A-6-107738. Or a polyfunctional monomer containing an electron-withdrawing group in butyl rubber (ethylene dimethacrylate, trimethylolpropane triacrylate, as described in JP-A-6-172547). (N, N′-m-phenylene dimaleimide, etc.) and an organic peroxide are added and butyl rubber is partially crosslinked. The degree of crosslinking of these partially crosslinked butyl rubbers can be represented by the insoluble content (gel content) in a solvent such as diisobutylene or cyclohexane which can completely dissolve the unvulcanized butyl rubber.
The partially crosslinked butyl rubber used in the present invention has a gel content in the range of 5% to 95% with respect to the solvent. Among them, the larger the gel content is, the more preferable, since the extender component can be retained in a large amount. Therefore,
The gel content of partially crosslinked butyl rubber is preferably 50%
˜95%, more preferably 65% to 95%. The partially crosslinked butyl rubber is preferably a terpolymer composed of isobutylene, isoprene and divinylbenzene, which is partially crosslinked with divinylbenzene. Further, as such partially crosslinked butyl rubber, for example, Polycerbutyl XL10000, XL
68102, XL30102, XL40302 (Polycer International Co., Ltd.) are commercially available. Among them, "Polycerbutyl X
L 10000 "(gel content in cyclohexane solvent is 70% to 85%) is preferable.

The extender component used in the present invention is a softening agent for reducing rubber hardness and a plasticizer generally added to rubber. As a softening agent, process oil (paraffin-based, naphthene-based, aroma-based), vegetable oil
(Castor oil, rapeseed oil, soybean oil, palm oil, coconut oil, peanut oil, cottonseed oil, wood wax, pine oil, olive oil, etc.), and synthetic softeners can be used. As the plasticizer, phthalic acid derivative, adipic acid derivative, azelaic acid derivative, sebacic acid derivative, maleic acid derivative, fumaric acid derivative, trimetic acid derivative, citric acid derivative, itaconic acid derivative, oleic acid derivative, ricinoleic acid derivative, stearin Examples thereof include acid derivatives, phosphoric acid derivatives, glutaric acid derivatives, glycolic acid derivatives, glycerin derivatives and epoxy derivatives.
It is preferable that these extender components have good compatibility with the partially crosslinked butyl rubber, that is, those having a small solubility parameter. Further, as the extender component, two or more of the above components may be mixed and used. A preferred extender component is a softening agent, more preferably a process oil, and further preferably a paraffinic process oil. The extender component is used in a proportion of 50 to 200 parts by weight, preferably 70 to 150 parts by weight, based on 100 parts by weight of the partially crosslinked butyl rubber.
If the extender component is less than 50 parts by weight, the desired low hardness cannot be achieved, and if it exceeds 200 parts by weight, the kneading property is deteriorated and bleeding of the extender component is likely to occur.

The rubber composition of the present invention may further contain a filler, a vulcanizing agent, a processability-improving polymer material and / or other rubber compounding agent in addition to the above components.
The filler is to reinforce the rubber material, which includes inorganic fillers such as carbon black, clay, talc, calcium carbonate, silica, cork powder, cellulose,
Included are organic fillers such as ebonite, and other fillers and reinforcing agents commonly incorporated in rubber. These fillers are based on 100 parts by weight of partially crosslinked butyl rubber,
It may be used in a proportion of 10 to 100 parts by weight, preferably 10 to 50 parts by weight.

Examples of the vulcanizing agent include organic peroxides and vulcanizing systems generally used for vulcanizing butyl rubber, such as sulfur, quinoids, resins, sulfur donors and low sulfur high vulcanization accelerators. . However, sulfur is not desirable because it corrodes other equipment parts, while organic peroxides give rubber materials having a low compression set, so that organic peroxides are preferably used in the present invention. Conventionally,
When peroxide was used for crosslinking and curing butyl rubber, decomposition reaction of the main chain occurred, and a satisfactory cured product was not obtained. Therefore, although a sulfur-based vulcanizing agent has been used, since the rubber composition of the present invention has a partially crosslinked butyl rubber as a main component, a peroxide can be used as a vulcanizing agent. Examples of organic peroxides include 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and dicumyl peroxide. These organic peroxides may be used in a proportion of 2 to 10 parts by weight, preferably 2 to 5 parts by weight, based on 100 parts by weight of the partially crosslinked butyl rubber.

The processability-improving polymer material is a polymer material for improving the kneadability of a rubber composition. Such polymer materials include natural rubber and synthetic rubber (IR, B
R, SBR, CR, NBR, IIR, EPM, EPD
M, acrylic rubber, EVA, urethane rubber, silicon rubber, fluororubber, etc.) and thermoplastic elastomers (styrene-based, olefin-based, vinyl chloride-based, ester-based,
Amide type, urethane type elastomer, etc.) are included.
These processability-improving polymer materials are partially crosslinked butyl rubber 1
0 to 100 parts by weight, preferably 0
˜50 parts by weight, more preferably 0 to 30 parts by weight.

Examples of other rubber compounding agents include general rubber compounding agents such as antioxidants, antioxidants, lubricants and flame retardants. These compounding agents may be compounded in the amounts usually used.

The rubber composition of the present invention can be produced by kneading the respective components by a known method. For example, using an open roll or closed kneading machine (intermix, kneader, Banbury mixer, etc.), first masticate partially crosslinked butyl rubber, then add kneading-improving polymer material, and further add filler and extender. It can be produced by adding components, a vulcanizing agent and other compounding agents for rubber and kneading. The kneading temperature may be 25 to 120 ° C. The production of the vibration damping rubber material from the rubber composition can be carried out, for example, by compression press molding, preferably transfer molding.
The molding temperature may be 130-170 ° C and the molding time may be within 20 minutes, preferably 4-10 minutes.

[0019]

EXAMPLES The present invention will be described in more detail with reference to the following examples. The present invention is not limited to these examples. In the following examples, the hardness is JIS K62.
Type A durometer hardness was measured according to 53. The hardness was also measured with a spring type hardness tester (Asker C type hardness meter: Kobunshi Keiki Co., Ltd.). The measurement temperature was 24 ° C. The compression set (c-set) is JIS K
According to 6262, the measurement was performed at 70 ° C. for 24 hours. Loss tangent (tan-δ) is a viscoelastic spectrometer: type VE
It was measured at 25 ° C./30 Hz by S-F-III (Iwamoto Seisakusho). The bleeding property of process oil is 80 ℃ × 80% Rh
After 720 hours of storage, evaluation was made by observing the cut surface according to the following criteria: ⊚: no bleeding, ∘: slight bleeding, Δ: moderate bleeding, ×: large amount of bleeding. The roll tackiness during kneading was evaluated according to the following criteria: ◎: easily peeled from the roll, ○: a little adhered but peeled off (no problem in workability), △: a considerable amount adhered (work Difficult to do), ×: Adhesive to both rolls (work not possible).

Example 1 Partially cross-linked butyl rubber (XL 10000: Polycer International Co.) 95 parts by weight, styrene-butadiene rubber
(SBR) (Nipol 1778J: Nippon Zeon Co., Ltd.) 5 parts by weight, paraffinic process oil 120 parts by weight, HAF-HS black 20 parts by weight, stearic acid 1 part by weight and organic peroxide 2 parts by weight with an open roll. 1. At 50-60 ° C
The rubber composition of the present invention was obtained by kneading for 5 hours. Using a press molding machine, this rubber composition
The rubber material for vibration isolation of the present invention was obtained by heating at 10 ° C. for 10 minutes to crosslink. Durometer hardness of this rubber material is A6, Asker C hardness is 18, c-set
Was 10% or less, and tan-δ was 0.16. Further, both the bleeding property of the process oil and the roll tackiness during kneading were good.

Examples 2 to 6 Using the formulations shown in Table 1 below, each component was kneaded in the same manner as in Example 1 to prepare a rubber composition, and then a rubber composition for vibration damping was prepared from this rubber composition. Obtained. Table 2 below shows the measurement results of the durometer hardness, Asker C hardness, compression set and loss tangent, and the bleeding property of the process oil and the roll tackiness during kneading.

Comparative Examples 1 to 3 Using the formulations shown in Table 1 below, each component was kneaded in the same manner as in Example 1 to prepare a rubber composition, and then a rubber material for vibration isolation was prepared from this rubber composition. Obtained. Table 2 below shows the measurement results of the durometer hardness, Asker C hardness, compression set and loss tangent, and the bleeding property of the process oil and the roll tackiness during kneading.

[0023]

[Table 1] * 1: XL 10000 (Polycer International) * 2: Styrene-butadiene rubber, Nipol 1778J (Zeon Corporation) * 3: Butyl rubber, Butyl 268 (JSR) * 4: Ethylene-propylene-diene terpolymer, EP-
98 (JSR Co., Ltd.); Contains 75 parts by weight of process oil per 100 parts by weight of polymer * 5: No Solex (Zeon Corporation) * 6: Styrene / ethylene / propylene / styrene block copolymer

[0024]

[Table 2]

As is clear from Table 2, by crosslinking and curing the rubber composition of the present invention, a rubber material having a low hardness, a small compression set and a large loss tangent can be obtained. In addition, there is no bleeding of process oil, and there is no problem of roll adhesion during kneading. On the other hand, in the comparative example, it was not possible to obtain one having all of the low hardness, the compression set, the loss tangent, the bleeding property of the process oil, and the roll tackiness during kneading.

[0026]

By cross-linking and curing the rubber composition of the present invention, the durometer hardness according to JIS K6253 is A15 or less, the Asker C hardness is 10 or more, and the compression set (70 ° C. × 24 hours). Of 20% or less and a loss tangent (25 ° C., 30 Hz) of 0.1 or more can provide a vibration-proof rubber material. Rubber materials having such characteristics are used for audio equipment, computer-related equipment or game equipment CDs, MDs, CD-ROMs, CD-Rs, CD-Rs.
It is particularly suitable for use for anti-vibration of W, DVD-ROM, DVD-RAM and the like. Further, the rubber composition and the vibration-proof rubber material of the present invention have a good kneading property even though they contain a large amount of the extender component, have a high retainability of the extender component, and suppress their bleeding. To be

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kuramochi 5-19-18 Higashikawaguchi, Kawaguchi City, Saitama Prefecture (56) References JP 56-43380 (JP, A) JP 10-36597 (JP, A) JP-A-6-107738 (JP, A) JP-A-9-71700 (JP, A) JP-A-5-59235 (JP, A) JP-A-2-120347 (JP, A) JP-B-60 −43865 (JP, B1) (58) Fields surveyed (Int.Cl. ⁷ , DB name) C08L 23/00-23/36 C08K 3/00-13/08 F16F 15/08

Claims (2)

(57) [Claims] 1. A rubber composition comprising 50 parts by weight to 200 parts by weight of an extender component, 0 parts by weight to 50 parts by weight of a processability-improving polymeric material and 100 parts by weight of a partially crosslinked butyl rubber, and a vulcanizing agent. JI
Durometer hardness according to SK6253 is A15 or less, Asker C hardness is 10 or more, JIS K6
A vibration isolation rubber material having a compression set of 262 (70 ° C. × 24 hours) of 20% or less and a loss tangent (25 ° C., 30 Hz) of 0.1 or more. 2. The anti-vibration rubber material according to claim 1, wherein the rubber composition further contains a filler and / or another compounding agent for rubber.