JP3441682B2 - Composition for anti-vibration rubber and anti-vibration rubber - 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 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.

Conventionally, for the anti-vibration rubber for such an application,
Butyl rubber with a high loss tangent and excellent vibration damping performance
(JP-A-9-3278, JP-A-9-71700) and halogenated butyl rubber (JP-A-3-126742, JP-A-5-59235, JP-A-5-194807) have been used. However, all of the anti-vibration rubbers described in these documents have a durometer hardness of A20 or more according to JIS K6253, and are not ultra-low hardness anti-vibration rubbers of A15 or less.

In order to obtain an ultra-low hardness vibration-proof material using these butyl rubbers and halogenated butyl rubbers, a large amount of extender components such as process oils must be added to the raw material composition. However, when a large amount of the extender component is added, the kneading property of the raw material composition deteriorates (the raw material composition adheres to the roll). In addition, the molded vibration-proof rubber has low mechanical strength, particularly low breaking strength, and process oil bleeds. As described above, butyl rubber and halogenated butyl rubber have excellent vibration damping performance, but have a problem that it is difficult to achieve ultra-low hardness.

Further, a vibration-proof rubber using a partially crosslinked butyl rubber is also known. In Japanese Examined Patent Publication No. 60-43865,
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 is described. However, the damping material described in this document is a spring type hardness tester having a hardness of 18 to 25.5, which is aimed at a durometer hardness of A15 or less according to JIS K6253 which is a target of the present invention. is not. The applicant's earlier application (Japanese Patent Application No. 10-2170)
No. 65) describes a rubber composition obtained by mixing 50 to 200 parts by weight of an extender component with 100 parts by weight of partially crosslinked butyl rubber. Partially cross-linked butyl rubber has a high oil retention, good kneadability even when filled with a large amount of oil, the vibration-proof rubber obtained by cross-linking and curing this rubber composition has an ultra-low hardness, Bleed of oil is suppressed.

However, when partially crosslinked butyl rubber is used,
There was a problem that the breaking strength was lower than when butyl rubber or halogenated butyl rubber was used and the breaking elongation was also small. If the breaking strength is low and the breaking elongation is small, the molded product may break or break when the molded product is released from the mold or the anti-vibration rubber is attached to the object. Further, if a large vibration is applied during use, the anti-vibration rubber may be torn.

Further, a rubber composition containing a partially crosslinked butyl rubber and a non-partially crosslinked butyl rubber is also known. Japanese Unexamined Patent Publication (Kokai) No. 62-70436 describes a rubber molded product molded from a mixture of a partially crosslinked butyl rubber and a halogenated butyl rubber in a specific ratio. This rubber molded product is intended to be used as a plug body such as a closed container, and has a different application from the anti-vibration rubber of the present application.
Japanese Patent Application Laid-Open No. 10-36597 describes a rubber composition for high-strength adhesive tape containing a specific cross-linked butyl rubber and a non-cross-linked butyl rubber. This rubber composition is for producing a high-strength adhesive tape (used for adhering a vulcanized rubber sheet) having a penetration of 70 to 100, and has a different application from the composition for vibration-proof rubber of the present application. .

[0009]

SUMMARY OF THE INVENTION An object of the present invention is to provide a vibration-proof rubber having low hardness, excellent vibration-proof performance and good mechanical strength, and a method for producing such a vibration-proof rubber. It was to provide a rubber composition. This composition
It must be easy to manufacture and have excellent processability.

[0010]

Means for Solving the Problems As a result of intensive studies to achieve the above object, the present inventors have made a rubber component a mixture of partially crosslinked butyl rubber and non-partially crosslinked butyl rubber, and prepared a large amount of extract in this mixture. By adding a tender component and a vulcanizing agent, a composition for vibration damping rubber having good kneading properties can be obtained. By crosslinking and curing this composition for vibration damping rubber, it has low hardness and vibration damping performance. It has been found that an anti-vibration rubber having excellent mechanical properties and improved mechanical strength can be obtained.

That is, the present invention is a partially crosslinked butyl rubber.
A composition for anti-vibration rubber, comprising (A), butyl rubber (B) which is not partially crosslinked, extender component (C) and vulcanizing agent (D). Ratio) is 10/90 to 60/40;
And · (A + B) / C blending ratio (weight ratio) is 100/30 to 15
The present invention provides a vibration-proof rubber composition which is 0; The present invention also provides a vibration-proof rubber obtained by cross-linking and curing the above composition for a vibration-proof rubber, which has a durometer hardness of A15 or less and a durometer hardness of E10 or more defined in JIS K6253. Is provided.

The anti-vibration rubber of the present invention is JIS K6253.
In the type A durometer hardness specified in
It has a hardness of 5 or less, preferably A10 or less. With such a low hardness, the frequency range in which the vibration damping effect can be exerted is widened, and a preferable result as a vibration damping rubber can be obtained. If it is harder than this, the demand for lowering the hardness of the anti-vibration rubber cannot be met. The anti-vibration rubber of the present invention has a JI
The type E durometer hardness defined by SK6253 has a hardness of E10 or more, preferably E15 or more. If it is softer than this, the mechanical strength of the anti-vibration rubber decreases. Further, there arises a problem that it becomes difficult to maintain the posture of the optical disc device. Furthermore, the anti-vibration rubber of the present invention,
It is preferable to have a loss tangent (25 ° C., 30 Hz) of 0.1 or more.

[0013]

The present invention will be described in more detail below. Partially cross-linked butyl rubber used in the present invention
(A) means, for example, as described in JP-A-6-107738, vinyl aromatic compound (styrene, divinylbenzene, etc.) and organic peroxide are added to butyl rubber to partially add butyl rubber. Obtained by cross-linking,
Alternatively, as described in JP-A-6-172547, a polyfunctional monomer containing an electron-withdrawing group in butyl rubber (ethylene dimethacrylate, trimethylolpropane triacrylate, N, N'-m-phenylene dimaleimide, etc.) ) And an organic peroxide are added, and the butyl rubber is partially cross-linked.

The degree of crosslinking of these partially crosslinked butyl rubbers can be expressed 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 of 5 with respect to the solvent.
% To 95%. 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 the partially crosslinked butyl rubber is preferably 50% to 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 a partially crosslinked butyl rubber, for example, Polycerbutyl XL1000
0, XL68102, XL30102, XL40302
(Polcer International Inc.) is commercially available,
Among them, “Polycerbutyl XL 10000” (gel content in cyclohexane solvent is 70% to 85%), which is a grade having a high degree of crosslinking, is preferable.

As the butyl rubber (B) which is not partially crosslinked in the present invention, butyl rubber and halogenated butyl rubber (chlorinated butyl rubber, brominated butyl rubber) can be used. Of these, halogenated butyl rubber is preferably used. The reason is that when halogenated butyl rubber is used, it can be vulcanized with a metal oxide. Further, halogenated butyl rubber has an advantage that it leads to improvement in productivity because it is vulcanized faster than normal butyl rubber. On the other hand, when normal butyl rubber is used, it is necessary to perform sulfur vulcanization. However, when sulfur is used for the vulcanization system, unreacted sulfur may remain in the rubber and hydrogen sulfide gas may be generated.
This gas is not preferable because it may cause corrosion of contacts in an audio system or a computer.

The compounding ratio (weight ratio) of the partially crosslinked butyl rubber (A) and the partially uncrosslinked butyl rubber (B) is A / B =
10/90 to 60/40, preferably A / B = 20/8
It is 0-40 / 60. By blending in this ratio, good kneadability of the rubber composition can be obtained even when a large amount of extender components are blended,
The mechanical strength of the anti-vibration rubber to be molded is also improved.
When the ratio of the component A is more than 60, the vibration-proof rubber has a low breaking strength and a low elongation, and the vibration-proof rubber is likely to be broken or torn. If the ratio of the component A is less than 10, the kneading processability of the rubber composition will be poor. Further, the breaking strength of the vibration-proof rubber is also reduced.

Extender component used in the present invention
(C) is a softening agent for lowering 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,
Palm oil, peanut oil, cottonseed oil, wood wax, pine oil, olive oil, etc.) as well as 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,
Examples thereof include citric acid derivative, itaconic acid derivative, oleic acid derivative, ricinoleic acid derivative, stearic acid derivative, phosphoric acid derivative, glutaric acid derivative, glycolic acid derivative, glycerin derivative, and epoxy derivative.

These extender components (C) are partially cross-linked butyl rubber (A) and partially non-cross-linked butyl rubber.
Those having good compatibility with (B), that is, those having a small difference in solubility parameter are preferred. 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 compounding ratio (weight ratio) of the extender component (C) to the total amount of the partially crosslinked butyl rubber (A) and the partially uncrosslinked butyl rubber (B) is (A + B) / C = 100 /
30-150, preferably (A + B) / C = 100/60
~ 100.

Examples of the vulcanizing agent (D) include organic peroxides, metal oxides, sulfur, quinoids, resins and low sulfur high vulcanization accelerators. Sulfur is undesirable because it corrodes other equipment components. Two or more kinds of these vulcanizing agents may be used in combination. Butyl rubber not partially crosslinked
When using halogenated butyl rubber as (B),
The combined use of an organic peroxide and a metal oxide as the vulcanizing agent (D) is preferable because the physical properties of each polymer are easily brought out by the action of co-crosslinking. The organic peroxide is 1,
Known compounds such as 1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane and dicumyl peroxide can be used. As the metal oxide, usual ones such as zinc oxide, magnesium oxide and lead oxide can be used.

The compounding ratio (weight ratio) of the vulcanizing agent (D) to the total amount of the partially crosslinked butyl rubber (A) and the partially uncrosslinked butyl rubber (B) is (A + B) / D = 100/2 to 15, Preferably (A + B) / D = 100 / 3-10.

The anti-vibration rubber composition of the present invention may further contain a processability-improving polymer material, a filler and / or other compounding agents for rubber, in addition to the above components.

The processability-improving polymer material is a polymer material used for the purpose of improving the kneadability of the rubber composition. Such polymer materials include natural rubber and synthetic rubber.
(IR, BR, SBR, CR, NBR, EPM, EPD
M, acrylic rubber, EVA, urethane rubber, silicone rubber, fluororubber, etc.), and thermoplastic elastomer
(Styrene series, olefin series, vinyl chloride series, ester series, amide series, urethane series elastomer, etc.) are included. These processability-improving polymer materials have a total amount of partially crosslinked butyl rubber (A) and partially uncrosslinked butyl rubber (B) of 1
0 to 100 parts by weight, preferably 0
˜50 parts by weight, more preferably 0 to 30 parts by weight.

The filler is to reinforce the anti-vibration rubber and includes carbon black, clay, talc,
Inorganic fillers such as calcium carbonate and silica, cork powder,
Included are organic fillers such as cellulose, ebonite, and other fillers and reinforcing agents commonly incorporated into rubber. These fillers may be used in a proportion of 10 to 100 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the total amount of the partially crosslinked butyl rubber (A) and the partially uncrosslinked butyl rubber (B). .

Other compounding agents for rubber include general rubber compounding agents such as anti-aging agents, antioxidants, lubricants and flame retardants. These compounding agents may be compounded in the amounts usually used.

The anti-vibration rubber composition of the present invention can be produced by kneading the components by a known method. For example, open roll or closed kneader (intermix, kneader, Banbury mixer, etc.)
First, masticate the butyl rubber that is not partially crosslinked, then add the partially crosslinked butyl rubber, and then add the processability-improving polymer material, filler, extender component, vulcanizing agent and other compounding agents for rubber. It can be manufactured by kneading. The kneading temperature is 25 to 120
It may be in ° C.

The vibration-proof rubber can be produced from the composition for vibration-proof rubber, for example, by compression press molding, preferably transfer molding. Molding temperature is 130-1
It may be at 70 ° C. and the molding time may be within 20 minutes, preferably 4-10 minutes.

[0029]

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.
53 Type A Durometer Hardness and Type E
The durometer hardness was measured. The measurement temperature was 24 ° C. The breaking strength and breaking elongation were measured as follows. That is, the side surface of a molded cylindrical anti-vibration rubber (see FIG. 1) was cut in the longitudinal direction and developed into a strip shape to make a test piece, which was measured using Strograph R (Toyo Seiki Co., Ltd.) did. Loss tangent (tan-δ) is 2 with a viscoelastic spectrometer: type VES-F-III (Iwamoto Seisakusho)
It was measured at 5 ° C./30 Hz. Compression set (c-set) is JI
It was measured at 70 ° C. for 24 hours according to SK6262.

The bleeding property of the process oil is 80 ° C. × 80
After storage for% Rh × 720 hours, evaluation was made by observing the cut surface of the anti-vibration rubber according to the following criteria: ⊚: no bleeding, ∘: slightly bleeding, Δ: moderately bleeding, ×: a 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 70 parts by weight of chlorinated butyl rubber (Chlorobutyl 1066: Exxon) was masticated, and then partially crosslinked butyl rubber.
(XL 10000: Policer International, Inc.) 3
Add 0 parts by weight of paraffinic process oil (PW-
32: Idemitsu Kosan Co., Ltd.) 80 parts by weight, carbon black (Asahi
# 55: Asahi Carbon Co., Ltd.) 20 parts by weight, stearic acid 1 part by weight, zinc oxide 5 parts by weight, organic peroxide (Perk Mill D)
-40: Nippon Oil and Fats Co., Ltd.) and 1 part by weight of zinc diethyldithiocarbamate (Axel EZ: Kawaguchi Chemical Co., Ltd.), and kneading with an open roll at 50-60 ° C. for 2 hours to prevent the present invention. A composition for vibrating rubber was obtained.
This anti-vibration rubber composition was treated with a press molding machine to obtain 15
By heating at 0 ° C. for 5 minutes for crosslinking, the cylindrical vibration-proof rubber of the present invention shown in FIG. 1 was obtained. The side surface of this cylindrical vibration-proof rubber was cut in the longitudinal direction and developed into a strip shape to obtain a test piece. The hardness of this anti-vibration rubber is type A durometer A
3, the type E durometer was E17. The breaking strength was 0.7 MPa and the breaking elongation was 600%. The loss tangent (tan-δ) was 0.22 and the compression set (c-set) was 10%. Further, both the bleeding property of the process oil and the roll tackiness during kneading were good.

Example 2 and Comparative Examples 1 and 2 Using the formulations shown in Table 1 below, the components were kneaded in the same manner as in Example 1 to prepare a composition for vibration-proof rubber, and then the composition was prepared from this composition. The anti-vibration rubber was obtained. Type A durometer hardness,
Table 1 below also shows the results of measurement of type E durometer hardness, breaking strength, breaking elongation, loss tangent and compression set, and the results of examining the bleeding property of the process oil and the roll tackiness during kneading.

[0033]

[Table 1] * 1: Chlorobutyl 1066 (Exxon) * 2: XL 10000 (Polycer International) * 3: PW-32 (Idemitsu Kosan) * 4: Asahi # 55 (Asahi Carbon) * 5: Dicumyl peroxide: Perkmill D -40 (NOF Corporation) * 6: Zinc diethyldithiocarbamate: Accel EZ
(Kawaguchi Chemical Co., Ltd.)

As is clear from Table 1, the composition for vibration-proof rubber according to the present invention has a low hardness when cross-linked and cured.
An anti-vibration rubber having excellent mechanical strength and no bleeding of process oil was obtained. In addition, the problem of roll adhesion did not occur when kneading the composition for vibration-proof rubber. On the other hand, in the comparative example, none satisfying all of these items was obtained.

[0035]

By cross-linking and curing the composition for vibration damping rubber of the present invention, a vibration damping rubber having a durometer hardness defined by JIS K6253 of A15 or less and a durometer hardness of E10 or more can be obtained. can get. This anti-vibration rubber has excellent anti-vibration performance and mechanical strength,
Computer-related device or game device CD, M
D, CD-ROM, CD-R, CD-RW, DVD-RO
It is particularly suitable for use for anti-vibration of M, DVD-RAM and the like. Further, the composition for vibration isolating rubber and the vibration isolating rubber of the present invention have a good kneading property of the composition even though they contain a large amount of the extender component, and the composition of the extender component from the vibration isolating rubber is Bleed is suppressed.

[Brief description of drawings]

FIG. 1 is a schematic view illustrating the shape of an anti-vibration rubber of the present invention.
It is (cross-sectional view).

─────────────────────────────────────────────────── ─── Continuation of front page (56) References JP 2000-103920 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C08L 23/00-23/36 C08K 3/00 -13/08 C08J 3/24 F16F 15/08

Claims (4)

(57) [Claims] 1. A partially crosslinked butyl rubber (A), a partially uncrosslinked halogenated butyl rubber (B), and an extender component.
A composition for anti-vibration rubber, comprising (C) and a vulcanizing agent (D), wherein the A / B compounding ratio (weight ratio) is 10/90 to 60/40;
And · (A + B) / C blending ratio (weight ratio) is 100/30 to 15
0; The composition for a vibration-proof rubber which is 2. The anti-vibration rubber composition according to claim 1, wherein the vulcanizing agent (D) is a combination of an organic peroxide and a metal oxide. 3. A composition obtained by cross-linking and curing the composition for vibration isolating rubber according to claim 1 or 2, which is JIS K6.
An anti-vibration rubber having a durometer hardness of A15 or less and a durometer hardness of E10 or more as defined in 253. 4. The anti-vibration rubber according to claim 3, which has a loss tangent (25 ° C., 30 Hz) of 0.1 or more.