JP2003105311A - Vibration-insulating rubber for reproducing device of noncontact disc-like recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration-insulating rubber having a low hardness and a high loss tangent and therefore capable of being suitably used as the vibration-insulating rubber for the reproducing device of a noncontact disc-like recording medium. SOLUTION: This vibration-insulating rubber for the reproducing device of the noncontact disc-like recording medium is made of a thermoplastic material, wherein the thermoplastic material is given by adding a softener to a thermoplastic elastomer, has a hardness of <=10 when measured by a JIS-A type durometer, and has a loss tangent of >=0.13 when measured at a temperature of 25 deg.C and an input vibrational frequency of 11 Hz. Because the vibration-insulating rubber has the hardness of <=10, its propagation ratio of vibration is reduced when a disc is rotated at a high speed, i.e., when data are read, so that the rubber much contributes to inhibition of generation of resonance and propagation of vibration to the outside. Because the rubber has the loss tangent of >=0.13, the propagation ratio of vibration is reduced when the disc is rotated at a low speed, i.e., when data are written, so that the rubber much contributes to the inhibition of generation of resonance and propagation of vibration to the outside. Thus, the vibration-insulating rubber is excellent in vibration-insulating characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to audio equipment including consumer use, video equipment, information equipment, various precision equipment, and particularly C
D, CD-ROM, CD-R / RW, DVD, DVD-
For anti-vibration use of a device (referred to as a "reproducing device" in the present specification) for reproducing / recording data on a disk-shaped recording medium such as a ROM, a DVD-RAM, a magneto-optical disk, and a hard disk by a non-contact method. Regarding anti-vibration rubber used.

[0002]

2. Description of the Related Art Conventionally, a reproducing apparatus for a disc-shaped recording medium as described above has a structure in which a disc-shaped recording medium is rotated in order to prevent disturbance vibration from being transmitted to a mechanical chassis having a reproducing mechanism such as a pickup. In order to prevent internal vibration such as drive source vibration generated by a motor or rotational vibration of the disk-shaped recording medium from being transmitted to the outside,
An anti-vibration rubber is attached between the housing of the playback device and the mechanical chassis.

Since this anti-vibration rubber is required to have characteristics of low hardness and softness and large loss tangent (tan δ), the hardness is 30 according to JIS-A type (measurement using a type A durometer according to JIS K6253). Vulcanized rubbers such as butyl rubber and polynorbornene rubber, which have characteristics of front and rear and loss tangent of about 0.2, have been used. However, in recent years, for example, when a reproducing device such as a CD-ROM built in a personal computer is taken as an example, the anti-vibration rubber having the above-described characteristics has an anti-vibration effect which is commensurate with the increase in speed due to the further increase in rotation speed. In some cases, it cannot be exhibited, and a further low hardness anti-vibration rubber of JIS-A type of 20 or less is required.

[0004]

To reduce the hardness of the vibration-proof rubber made of vulcanized rubber to 20 or less in JIS-A type,
It is necessary to add a large amount of oil to the rubber compound. However, if a large amount of oil is added, the tackiness of the rubber compound becomes high, and the vulcanization time increases and productivity decreases. Further, since burrs are generated in the vulcanization step, the cost for this deburring step is high and the workability is deteriorated.

On the other hand, an anti-vibration rubber made of a thermoplastic elastomer which does not have a vulcanization step has been studied in place of the vulcanized rubber having such problems, but the hardness of the thermoplastic elastomer itself is 20 in JIS-A type. Although it is possible to make the hardness as low as possible, the loss tangent is limited to 0.05 as far as the inventors of the present invention know, and this has a low effect of damping vibration.

An object of the present invention is to provide a vibration-proof rubber having a low hardness and a large loss tangent, which is suitable as a vibration-proof rubber for a reproducing apparatus for a non-contact type disc-shaped recording medium.

[0007]

[Means for Solving the Problems] That is, the present invention uses a thermoplastic elastomer as a main raw material and has a hardness of 10 or less in JIS-A type at 25 ° C. and an input vibration frequency of 11 Hz.
To provide a vibration-proof rubber for a non-contact disk-shaped recording medium reproducing apparatus, which is made of a thermoplastic material having a loss tangent of 0.13 or more.

According to this anti-vibration rubber, the hardness is JIS-A type 10 while the main component is the thermoplastic elastomer.
In the following, since the loss tangent has a value of 0.13 or more, the hardness is low, but the loss tangent is large and excellent vibration damping characteristics are provided. That is, since the hardness is 10 or less, the vibration transmissibility when the disk rotates at a high speed at the time of reading data is reduced, which greatly contributes to suppressing the occurrence of resonance and the transmission of vibration to the outside. Also, the loss tangent is 0.1
Since it is 3 or more, the vibration transmissibility when the disk rotates at a low speed at the time of writing data is reduced, which greatly contributes to suppressing the occurrence of resonance and the transmission of vibration to the outside.

The present invention also relates to a thermoplastic material which contains a softening agent in a thermoplastic elastomer, has a JIS-A type hardness of 10 or less, and has a loss tangent of 0.13 or more at 25 ° C. and an input vibration frequency of 11 Hz. An anti-vibration rubber for a non-contact type disc-shaped recording medium reproducing apparatus is provided.

According to this anti-vibration rubber, in addition to the characteristics of the thermoplastic material whose main raw material is the above-mentioned thermoplastic elastomer, a softening agent is added to the thermoplastic elastomer, so that it is miscible with the thermoplastic elastomer. A good and homogeneous thermoplastic material can be obtained.

In the present invention, the thermoplastic material is at least one selected from polybutene, paraffin oil and naphthenic oil per 100 parts by weight of thermoplastic elastomer, and the kinematic viscosity at 40 ° C. is 100 c.
Softening agent of St to 600 cSt: 50 parts by weight to 400
Provided is a vibration-proof rubber for a non-contact disk-shaped recording medium reproducing apparatus, which is a mixture of parts by weight.

According to this anti-vibration rubber, since the thermoplastic elastomer is mixed with a predetermined softening agent, it has a low hardness, a large loss tangent and an excellent anti-vibration property. Further, the thermoplastic elastomer and the softening agent have good miscibility and can be a homogeneous thermoplastic material. Further, the thermoplastic material does not have tackiness and has good workability.

The present invention also relates to a thermoplastic elastomer,
Provided is a vibration-proof rubber for a non-contact disk-shaped recording medium reproducing apparatus using a styrene-ethylene / butylene-styrene copolymer, a styrene-ethylene / propylene-styrene copolymer, or a mixture thereof.

According to this anti-vibration rubber, since a styrene-ethylene / butylene-styrene copolymer, a styrene-ethylene / propylene-styrene copolymer, or a mixture thereof is used as the thermoplastic elastomer, these copolymers are used. The ethylene / butylene part or the ethylene / propylene part of the polymer easily adsorbs the oil component, has excellent miscibility with the softening agent, and easily lowers the hardness of the thermoplastic material.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A vibration-proof rubber for a non-contact type disc-shaped recording medium reproducing apparatus of the present invention is made of a thermoplastic material containing a thermoplastic elastomer and a softening agent, and has a hardness of JIS.
-A type is characterized in that it is 10 or less, the loss tangent is 25C, and the input vibration frequency is 113 or more at 11 Hz.

The thermoplastic elastomer used in the present invention includes, for example, styrene-based, olefin-based, diolefin-based, vinyl chloride-based, urethane-based, ester-based, amide-based, hydrogenated products, epoxidized products, and maleated products thereof. Among them, the hard segment such as crystal structure and agglomerate structure and the soft segment such as amorphous structure form a micro phase-separated structure in which they are independently dispersed without being compatible with each other. Those that are present are preferable. Specifically, it is an elastomer such as styrene-butadiene-styrene and styrene-isoprene-styrene, but styrene-ethylene is improved in thermal stability and weather resistance by hydrogenating an unsaturated bond in the soft segment. / Butylene-styrene copolymer or styrene-ethylene / propylene-styrene copolymer is
It is preferable because the softening agent is easily absorbed in the ethylene / butylene part and the ethylene / propylene part.

As the softening agent, one that is liquid at room temperature and has good miscibility when blended with a thermoplastic elastomer is used, but polybutene, paraffin oil, naphthenic oil, etc., having a kinematic viscosity at 40 ° C. of 100 cSt. ~ 600
Those of cSt are preferred. The reason why these softening agents are used is that the loss tangent of the thermoplastic elastomer, which is less than 0.05, can be increased by blending the softening agent, and a thermoplastic material suitable as a vibration isolating rubber can be obtained. The kinematic viscosity of the softening agent is 300c at 40 ° C.
St to 600 cSt is more preferable because the loss tangent becomes large and the effect of vibration damping becomes high even with a small amount of compounding. However, if it exceeds 600 cSt, the thermoplastic material becomes tacky and difficult to process, and the miscibility with the thermoplastic elastomer becomes poor, and the oil component is easily separated. Further, if it is less than 100 cSt, it is difficult to increase the loss tangent, and if the obtained anti-vibration rubber is left at high temperature, the oil component scatters and escapes, which is not preferable because the loss tangent becomes low.

The blending amount of the softening agent is preferably 50 to 400 parts by weight with respect to 100 parts by weight of the thermoplastic elastomer,
It is more preferably 50 to 200 parts by weight. If it exceeds 400 parts by weight, the softening agent is liable to bleed out, giving tackiness to the obtained anti-vibration rubber, and lowering the mechanical strength to impair the function as a structural material. On the other hand, if the amount is less than 50 parts by weight, the decrease in hardness is small, and the suppression of the internal vibration due to the high speed rotation of the disk becomes insufficient.

The hardness of the thermoplastic material is 10 or less in JIS-A type, and the loss tangent is 0.13 or more.
The characteristics of the material are defined by hardness and loss tangent, which means that a material having excellent vibration damping characteristics is required when the optical disk or the like rotates at high speed and at low speed, and as a measure of whether or not this requirement is satisfied, This is because it is convenient to judge from two values, hardness and loss tangent. That is, if the hardness is greater than 10, resonance is likely to occur at high speed, which is not preferable.
If the loss tangent is smaller than 0.13, resonance is likely to occur at low speed rotation, which is not preferable.

In addition, since the anti-vibration rubber of the present invention is not actually bent or deformed with time when actually used, the anti-vibration rubber does not undergo compression set (test conditions) in accordance with JIS K6262. : 70 ° C; 22 hours), but 20%
It is preferably not more than, and further, the impact resilience is 30.
% Or less is preferable. For example, with respect to 100 parts by weight of Kraton G1650 (trade name: manufactured by Kraton Polymer Japan Co., Ltd.) as a thermoplastic elastomer, a kinematic viscosity at 40 ° C. as a softening agent is 381 cSt.
Diana Process Oil PW-380 (trade name:
(Made by Idemitsu Kosan Co., Ltd.): A thermoplastic material containing 200 parts by weight has these characteristics.

The thermoplastic material used in the present invention includes
Additives used for ordinary thermoplastic resins can be added as required. As this additive, for example,
Silica, talc, glass fiber, mica, graphite,
Fillers and reinforcing agents such as calcium carbonate and glass balloons,
Other antioxidants, ultraviolet absorbers, antistatic agents, flame retardants, lubricants, foaming agents, colorants, pigments, cross-linking agents, cross-linking aids,
Polyolefin resin, polystyrene resin, polyphenylene ether, various tackifiers, etc.,
Alternatively, a mixture thereof may be used.

The thermoplastic material is required to contain a softening agent in the thermoplastic elastomer by using a usual heating and kneading device such as a rubber mill, a Brabender mixer, a Banbury mixer, a kneader, a single screw extruder or a twin screw extruder. It can be manufactured by mixing a compounding agent and kneading by heating and melting. The processing of the vibration-proof rubber is performed by injection-molding a thermoplastic material obtained by heating, melting, and kneading into a desired shape to obtain the vibration-proof rubber for the non-contact disc-shaped recording medium reproducing apparatus of the present invention. be able to.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[0024]

【Example】

Example 1: As a thermoplastic elastomer,
Kraton G16 which is a styrene-ethylene / butylene-styrene block copolymer (hydrogenated block copolymer)
50 (made by Clayton Polymer Japan Co., Ltd.) 100
As a softening agent, the kinematic viscosity at 40 ° C. is 145 cSt in parts by weight.
100 parts by weight of Diana Process Oil PW-150 (manufactured by Idemitsu Kosan Co., Ltd.), which is a paraffin-based process oil, was mixed and kneaded with a twin-screw extruder to obtain pellets. This was molded with an injection molding machine at a cylinder temperature of 190 ° C. to prepare a test piece 1. This test piece 1
Hardness (JIS-A) and loss tangent (ta
nδ) was measured and the anti-vibration property was evaluated. Loss tangent is the measurement frequency (input vibration frequency) at room temperature (25 ° C)
It was measured by Rheovibron DDV-III (manufactured by A & D Co., Ltd.) under the condition of 11 Hz. In addition, the anti-vibration characteristics are obtained by conducting a vibration transfer test and determining the vibration transfer rate (d when the frequency of the input vibration is 150 Hz and 50 Hz).
B) was measured and evaluated. In the evaluation, those with excellent vibration damping properties were marked with ⊚, those with excellent vibration damping properties were marked with ◯, and those with poor vibration damping properties were marked with x. Table 1 shows the blending amount of each component of the test piece 1 and the test results.

[0026]

[Table 1]

Examples 2 to 9 and Comparative Examples 1 to 3: Test pieces were prepared in the same manner as in Example 1 using various raw materials having the compounding amounts shown in Table 1 to obtain test pieces 2 to 13. It was The same test as the test performed in Example 1 was performed on these test pieces. The results are shown in Table 1. However, the test piece 13
Since bleeding out of the softener occurred and it could not be used, the hardness and loss tangent were not measured, and the anti-vibration property was not evaluated.

The components shown in Table 1 are as follows. -Clayton G1650 (trade name: manufactured by Kraton Polymer Japan Co., Ltd.); styrene-ethylene / butylene-styrene block copolymer-Septon CJ002 (trade name: manufactured by Kuraray Plastics Co., Ltd.); styrene-ethylene / propylene-styrene co-polymer Combined PW150 (Diana Process Oil PW-150
(Brand name: manufactured by Idemitsu Kosan Co., Ltd.); Paraffin-based process oil (kinematic viscosity at 40 ° C. is 145 cSt) PW380 (Diana Process Oil PW-380)
(Brand name: manufactured by Idemitsu Kosan Co., Ltd.); Paraffin-based process oil (kinematic viscosity at 40 ° C. is 381 cSt) PW90 (Diana Process Oil PW-90 (brand name: manufactured by Idemitsu Kosan Co., Ltd.); Paraffin-based process oil ( Kinematic viscosity at 40 ° C. is 95 cSt) 15H (Idemitsu Polybutene 15H (trade name: manufactured by Idemitsu Petrochemical Co., Ltd.)); Polybutene (kinematic viscosity at 40 ° C. is 5)
50 cSt) NM280 (Diana Process Oil NM-280
(Product name: manufactured by Idemitsu Kosan Co., Ltd.); naphthenic oil (kinematic viscosity at 40 ° C. is 237 cSt)

As is clear from the results shown in Table 1,
The test pieces 1 to 10 have low vibration transmissibility regardless of whether the input vibration frequency is high or low, and it was confirmed that the vibration-proof rubber of the present invention has a vibration-damping property excellent in the vibration damping effect.

[0030]

According to the present invention, the hardness of JIS-A type is as low as 10 or less and the loss tangent at 25 ° C. and the input vibration frequency of 11 Hz is as large as 0.13 or more while using the thermoplastic elastomer. Thus, it is possible to obtain the anti-vibration rubber for the non-contact disc-shaped recording medium reproducing apparatus, which has excellent anti-vibration characteristics both when the disc-shaped recording medium is rotated at high speed and at low speed.

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Claims (3)

[Claims] 1. A thermoplastic elastomer containing a softening agent and having a JIS-A type hardness of 10 or less, 25
Loss tangent at input vibration frequency 11 Hz at 0.1
An anti-vibration rubber for a non-contact type disc-shaped recording medium reproducing apparatus, which is made of a thermoplastic material of 3 or more. 2. The thermoplastic material is at least one selected from polybutene, paraffin oil and naphthene oil, based on 100 parts by weight of thermoplastic elastomer.
Seed and kinematic viscosity at 40 ° C. is 100 cSt to 60
The anti-vibration rubber for a non-contact disk-shaped recording medium reproducing apparatus according to claim 1, wherein the softening agent having 0 cSt: 50 parts by weight to 400 parts by weight is blended. 3. The non-contact according to claim 1 or 2, wherein the thermoplastic elastomer is a styrene-ethylene / butylene-styrene copolymer, a styrene-ethylene / propylene-styrene copolymer, or a mixture thereof. Vibration-proof rubber for playback devices of disc type recording media.