JP2002212370A - Fluororubber vulcanization molded product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fluororubber vulcanization molded product with a slight increase in hardness and having excellent shock absorption and nontackiness by compounding a filler having a specific shape with a fluororubber. SOLUTION: This fluororubber vulcanization molded product is obtained by carrying out vulcanization molding of a rubber composition comprising a filler having 1-50 μm average particle diameter and >=5 aspect ratio or a fibrous or a needlelike filler having 1-500 μm average fiber length in an amount of 5-100 pts.wt. based on 100 pts.wt. of the fluororubber.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vulcanized fluororubber product. More specifically, the present invention relates to a vulcanized fluoro rubber molded article having excellent shock absorption and non-adhesiveness.

[0002]

2. Description of the Related Art Fluororubber has been widely used as a material for a shock absorbing stopper of a memory device head because of its damping characteristics and low outgassing characteristics. In rubber materials other than fluororubber, low-molecular volatile components are generated from rubber (outgassing), and there is a problem such as disk contamination, and among rubbers, fluororubber is the best. Further, the fluoro rubber material has a low rebound resilience and is used as a shock absorbing material for various memory device heads.

[0003] However, conventional fluororubber materials are:
There is adhesion to the head, and there is a malfunction depending on the model. For this reason, there is a method of making fluoro rubber with high rubber hardness to make it non-adhesive, but if the hardness is just high, the non-adhesive properties are insufficient and it is difficult to mount the stopper when incorporating it into the device. is there.

Conventionally, the rubber hardness of fluororubber has been adjusted mainly by carbon black. When carbon black is blended, the hardness increases. Therefore, in order to lower the rubber hardness, it was necessary to reduce the amount of carbon black. However, if the amount of carbon black is small, the amount of rubber increases, the adhesion increases, and a rubber hardness of 80 degrees (JIS
A) In the following, it was difficult to make the rubber non-adhesive.

[0005] Here, there is a method of roughening the surface of the fluororubber to make it non-adhesive.
The non-stickiness is insufficient. Further, the method of chemically non-adhesive treatment of the fluororubber surface requires a reduction in productivity and processing cost, and cannot respond to the recent HDD price competition.

For example, Japanese Patent Application Laid-Open No. 08-87842 describes a method of preventing the head from sticking by using a fluororubber molded body having an uneven surface or a tapered surface. The non-adhesiveness is not sufficient if only shrinks. In addition, UV curable resin composed of reactive oligomer, monomer, photoinitiator, pigment, etc. is used for stopper rubber to prevent adhesion,
Resin durability due to head impact (adhesion durability with rubber)
Is a problem, and when the resin is peeled off and the peeled resin powder is deposited on the disk, it becomes a serious defect.

Japanese Patent Application Laid-Open No. 05-98055 discloses that a fluororubber molded article is immersed in octahydropyrimidide (1,2-α) azepine or a solution thereof, washed, dried, and dried. It describes a method for producing a surface-modified fluorine-containing elastomer vulcanized molded article that is heat-treated at 300 ° C.
In this method, using a solvent such as acetone, it is bad for the environment,
When the immersion is performed for about 15 minutes, there is a problem that the rubber swells with the solvent and the compound contained in the rubber elutes into the solvent. Furthermore, about 5 hours for solvent drying and 1 hour for heat treatment
It takes about 5 hours or more, which lowers productivity and increases processing costs.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a filler having a specific shape which is excellent in shock absorption and non-adhesion by adding a filler having a specific shape to a fluororubber. It is to provide a rubber vulcanized molded product.

[0009]

SUMMARY OF THE INVENTION The object of the present invention is as follows.
From a rubber composition containing a filler having an average particle size of 1 to 50 μm and an aspect ratio of 5 or more or a fibrous or acicular filler having an average fiber length of 1 to 500 μm per 100 parts by weight of fluororubber, This is achieved by a vulcanized and formed fluororubber vulcanizate.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As the fluororubber, binary copolymers such as vinylidene fluoride / 6-propylene / tetrafluoroethylene / propylene, vinylidene fluoride / 6-propylene / 4-tetrafluoroethylene, fluorine Commercially available fluororubbers such as terpolymers such as vinylidene fluoride / 4 ethylene / perfluoro (alkyl vinyl ether) are used as they are. As a vulcanizing agent therefor, onium salts such as quaternary ammonium salts and quaternary phosphonium salts, organic oxides and the like are generally used.

[0011] As the filler compounded in the fluororubber,
Calcium carbonate, aluminum silicate, magnesium silicate, wollastonite (calcium silicate), zonotolite
(Calcium silicate), talc, mica, sericite, glass flakes, various metal foils, graphite, sheet iron oxide, sheet calcium carbonate, sheet aluminum hydroxide, sheet iron oxide, glass fiber, carbon fiber, aramid fiber , Vinylon fiber, alumina fiber, metal fiber, gypsum fiber, phosphate fiber, dawsonite, aluminum borate, asbestos, potassium titanate, acicular magnesium hydroxide, etc. Is used. As such a filler, the average particle size is 1 ~ 50μ
m, preferably in the range of 5 to 30 μm and having an aspect ratio of 5 or more. If the average particle size is less than 1 μm, the hardness of the vulcanized rubber is increased, the unevenness of the rubber surface is small, and sufficient non-adhesive properties cannot be obtained. On the other hand, if it exceeds 50 μm, the physical properties of the vulcanized rubber will be reduced, and the filler will fall off from the surface of the vulcanized rubber. If the aspect ratio is less than 5, unevenness on the surface of the vulcanized rubber is small, and sufficient non-adhesive properties cannot be obtained.

As the fibrous filler, fillers such as glass fiber, carbon fiber, aramid fiber, vinylon fiber, alumina fiber and metal fiber are used.

Examples of the acicular filler include potassium titanate, wollastonite, zonolite, phosphate fiber, gypsum fiber, dawsonite, aluminum borate, asbestos, acicular MgO, magnesium hydroxide, calcium carbonate, aluminum silicate, magnesium silicate Fillers such as are used.

As the fibrous filler and the acicular filler, fillers having an average fiber length of 1 to 500 μm, preferably 5 to 200 μm are used. If the average fiber length is less than 1 μm, the hardness of the vulcanized rubber becomes high, the unevenness of the rubber surface is small, and sufficient non-adhesive properties cannot be obtained. On the other hand, if it exceeds 500 μm, the physical properties of the vulcanized rubber will be reduced, and the filler will fall off from the surface of the vulcanized rubber.

[0015] By containing a filler comprising at least one of the above-mentioned fillers in an amount of 5 to 100 parts by weight, preferably 10 to 80 parts by weight, per 100 parts by weight of the fluororubber, the shock absorbing properties (rebound resilience properties) of the fluororubber are obtained. , And non-adhesive properties can be imparted.

If the amount of the filler is less than 5 parts by weight, unevenness of the rubber surface is small, and sufficient non-adhesive properties cannot be obtained. on the other hand,
If it exceeds 100 parts by weight, kneading and molding become difficult,
The hardness of the vulcanized rubber increases significantly.

The smaller the filler used, the smaller and smaller the irregularities on the rubber surface. Therefore, it is necessary to increase the compounding amount in order to obtain the non-adhesive property. Since it is large and large, non-adhesive properties can be obtained by reducing the blending amount.

The preparation of the rubber composition is carried out by using an intermix,
Kneading is performed by kneading using a closed kneader such as a kneader or a Banbury mixer or an open roll. For about 3 to 60 minutes, and a heat treatment (secondary vulcanization) is further preferably performed at about 120 to 250 ° C. for 1 to 24 hours to reduce the amount of outgas from the rubber. The higher the secondary vulcanization temperature and the longer the time, the lower the outgas amount.

The vulcanized molded product preferably has an uneven surface in order to stabilize its non-adhesive properties.
m, preferably in the range of 3 to 20 μm. As the method, a method of roughening the surface of the vulcanized rubber by sandblasting, a method of rubbing with sandpaper or the like,
A method of compression-molding with a compression mold having been subjected to an unevenness treatment and transferring the unevenness to the rubber surface is used. If it is smaller than the above range of the unevenness, the height of the unevenness is small and sufficient non-adhesive properties cannot be obtained. On the other hand, if it is larger than this, the contact area with the head becomes large, and sufficient non-adhesive properties cannot be obtained.

[0020]

The fluororubber vulcanizate according to the present invention can be used as a shock-absorbing stopper component of a memory device head by blending a filler having a specific shape into the fluororubber.
Assuming non-contamination to the environment, it is possible to achieve both impact absorption and non-adhesive properties for the head. When this vulcanized product is used as an impact absorbing stopper for HDD storage device heads, storage device heads such as in-vehicle disk devices using optical disks, disk devices for camera-integrated video recorders, etc., and printer heads, High shock absorption characteristics (low rebound resilience), no head adhesion (non-adhesion characteristics) in the main operating temperature range of the material, 0 to 40 ° C. It is possible to sufficiently satisfy required performances such as not contaminating or damaging the head, prevent the head guarantee area from being exceeded, reduce the inertial force applied to the head due to an impact, and shorten the control distance.

[0021]

Next, the present invention will be described by way of examples.

Example 1 100 parts by weight of fluoro rubber (Viton E60C manufactured by DuPont) MT carbon black 5 マ グ ネ シ ウ ム magnesium oxide 3 カ ル シ ウ ム calcium hydroxide 6 ビ ス bisphenol AF 2.3 ト リ triphenylbenzylphosphonium chloride 1.3 カ ル シ ウ ム calcium silicate (average diameter 3 μm, (Average length 25 μm) Each component of 40 〃 or more is kneaded with a kneader and open roll, and press vulcanized at 170 ° C. for 30 minutes and oven vulcanized (secondary vulcanization) at 200 ° C. for 24 hours. Was. During vulcanization molding,
A mold having a surface unevenness of 5 μm was used.

Example 2 In Example 1, 10 parts by weight of carbon fiber (average fiber diameter 15 μm, average fiber length 150 μm) was used instead of calcium silicate.

Example 3 In Example 1, 40 parts by weight of calcium carbonate (average diameter 1 μm, average length 5 μm) was used instead of calcium silicate.

Example 4 In Example 1, a mold having a surface unevenness of 0.5 μm subjected to vulcanization molding was used.

Comparative Example 1 The same procedure as in Example 1 was repeated except that calcium silicate was not used.
Was used.

Comparative Example 2 In Example 1, a mold having a surface unevenness of 5 μm was used without using calcium silicate.

Comparative Example 3 In Example 1, the amount of MT carbon black was changed to 40 parts by weight without using calcium silicate.

Comparative Example 4 In Example 2, the amount of carbon fiber was changed to 2 parts by weight.

Comparative Example 5 In Example 1, the same amount of granular calcium carbonate (average particle size: 1 μm) was used instead of calcium silicate.

The following items were measured for the vulcanized molded products obtained in the above Examples and Comparative Examples, and the results shown in the following table were obtained. Normal value: JIS K-6253, JIS K-6251 compliant Rebound resilience: Six sheets of 29 mm in diameter and 2 mm in thickness are piled up and measured at 0 ° C, 25 ° C and 40 ° C by Lupke method (JIS K-62
Adhesive strength: 3 inch aluminum substrate sputtered thin film disk, A
HDD equipped with voice coil motor VCM equipped with nano slider of lTiC thin film head arm and two different polarity magnets
Then, insert a cylindrical outer stopper rubber washed with water and ultrasonic cleaning into a stainless steel pin, contact the stopper rubber with the arm at 0 ° C for 1 hour, and measure the adhesive force at 0 ° C. At 0 ° C, the rubber adhesion is higher than that of the rubber, and the adhesion of the rubber surface tends to be higher.
The measurement was performed at 0 ° C. Table Example Comparative Example Measurement Items 1 2 3 4 1 2 3 4 5 Normal Value Hardness (Durometer A) 76 70 78 76 60 60 80 62 87 Tensile Strength (MPa) 12.5 10.8 11.7 12.5 11.2 11.2 17.0 11.0 15.1 Elongation (% ) 150 160 184 150 298 298 190 200 117 Surface roughness of molded product 6 15 5 2 0.5 5 5 7 6 Rz (μm) Rebound resilience 0 ° C (%) 8 13 10 8 8 8 10 9 10 25 ° C (% ) 11 7 5 11 12 12 12 12 12 40 ° C (%) 25 28 22 25 38 38 32 34 30 Adhesion 0 ° C (%) 12 15 14 20 100 60 40 58 30

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Claims (3)

[Claims] An average particle size of 1 to 50 μm and an aspect ratio of 5
A vulcanized fluororubber molded from a rubber composition containing the above filler or a fibrous or needle-like filler having an average fiber length of 1 to 500 μm per 5 parts by weight of fluororubber. 2. The fluororubber vulcanizate according to claim 1, wherein an uneven surface is formed at a depth of 1 to 50 μm on the surface of the vulcanized rubber. 3. The fluororubber vulcanizate according to claim 1, which is used as a shock absorbing stopper part.