JP2003080555A - Method for manufacturing cover integrated type gasket for hard disk driving - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a gasket for hard disk driving easy to manufacture, excellent in low outgassing properties, sealability, moisture permeability, adhesiveness, moldability or the like and having high dustproof properties. SOLUTION: A styrenic thermoplastic elastomer compound, which is prepared by adding 10-100 pts.wt. of a polypropylene, 10-200 pts.wt. of a plasticizer and 30-100 pts.wt. of a scaly inorganic filler to 100 pts.wt. of a styrenic thermoplastic elastomer, is injected in a mold in which an adhesive coated metal cover is inserted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a cover-integrated gasket for a hard disk drive. More specifically, it relates to a method of manufacturing a cover-integrated gasket for a hard disk drive, which is easy to manufacture and has improved low outgassing property.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and higher performance of electronic equipment products, it has been required to make the components smaller and thinner. From the viewpoint that assembly workability in the manufacturing process deteriorates when the components are made small, integration and combination of various components are required. At the same time, it is required to improve the performance of required characteristics such as outgassing property and sealing property.

Among electronic storage devices, for a gasket mounted as a drive cover of a hard disk which is particularly required to prevent entry of water and dust and to have low outgassing property, a rubber alone or a urethane foam sheet is made of stainless steel or aluminum. It is attached in a form sandwiched between metal covers, and it has been proposed that a metal cover made of stainless steel or the like and a rubber material such as fluororubber are joined by an adhesive and integrated to improve the assembling work. (Patent No.
2,517,797).

However, in this method, the gasket-shaped rubber is vulcanized and molded in a separate step in advance, and then bonded to the metal cover with an adhesive.
The process was long and complicated. In fact, the gasket vulcanization process takes several minutes, and since the gasket after vulcanization is thin and easy to be torn, and dust etc. are likely to adhere, it is necessary to repeatedly wash and select before assembling. A simplified method was desired.

In order to solve such a problem, a gasket material composed of a styrene-based block copolymer elastomer is proposed, in which a vulcanization step is not required as compared with a rubber material, the process can be simplified, and the material can be recycled and the cost can be reduced. (Patent No. 2,961,068).

Since this material is thin, soft, and easily sticky, the workability is extremely poor in the hard disk drive assembly work unless the gasket is fixed in advance by some method. As a countermeasure against this, it is necessary to pre-inject a styrene-based block copolymer elastomer gasket into what is called a frame body by injection molding in advance, and then to assemble and integrate it between the box body and lid body of the hard disk drive, etc. After all, other parts such as a frame are needed.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method of manufacturing a gasket for a hard disk drive, which is easy to manufacture and has excellent low outgassing property and sealing property.

[0008]

The object of the present invention is as follows.
Adhesive coating In a mold with a metal cover inserted, polypropylene resin 10 to 100 parts by weight, plasticizer 10 to 200 parts by weight and scaly inorganic filler 30 to 100 parts by weight per 100 parts by weight of styrene thermoplastic elastomer. This is achieved by a method of manufacturing a gasket integrated with a cover for a hard disk drive, which comprises injecting a styrene-based thermoplastic elastomer compound containing a part.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION As the stainless steel thermoplastic elastomer, polystyrene-poly (ethylene-propylene) -polystyrene triblock copolymer [SEPS],
Polystyrene-poly (ethylene / ethylene-propylene)
-Polystyrene triblock copolymer [SEEPS] or the like is used. SEPS is polystyrene-polyisoprene-
Obtained by hydrogenating a polystyrene block copolymer, SEEPS is a polystyrene- (butadiene-
It is obtained by hydrogenating an isoprene) random copolymer-polystyrene block copolymer.

The number average molecular weight of these styrenic thermoplastic elastomers is preferably 50,000 or more. If the number average molecular weight is less than this, the bleeding of the softening agent increases, the compression set increases, and there is a case in which it cannot withstand actual use. On the other hand, although the upper limit of the number average molecular weight is not particularly limited, it is usually about 400,000. The content of the amorphous styrene block of the styrene-based thermoplastic elastomer is
The range of 10 to 70% by weight, preferably 15 to 60% by weight is preferable. The glass transition temperature (Tg) of the amorphous styrene block portion is preferably 60 ° C or higher, more preferably 80 ° C or higher. Further, the polymer of the portion connecting the amorphous styrene blocks at both ends is preferably amorphous. These styrene-based thermoplastic elastomers are mainly used alone, but two or more kinds may be blended and used. In practice, Clera products Septon 2006 [SEPS], Septon 4055 [SEEPS], etc. that satisfy these conditions are used.

The polypropylene resin is a homopolymer of propylene or a copolymer of propylene and a small amount of α-olefin (eg ethylene, 1-butene, 1-hexene, 4-methyl-1-pentene). A crystalline polymer is used. The polypropylene resin is used in an amount of 10 to 100 parts by weight, preferably 20 to 80 parts by weight, based on 100 parts by weight of the styrene thermoplastic elastomer. If the compounding amount is more than this range, the hardness becomes high, while if the compounding amount is less than this range, the fluidity becomes poor and the injection molding becomes difficult.

The plasticizer is not particularly limited as long as it is used for ordinary rubbers and thermoplastic elastomers. For example, petroleum softeners such as process oil, lubricating oil, paraffin oil, castor oil, linseed oil. , Rapeseed oil,
Fatty oil type softeners such as coconut oil and ester type plasticizers such as dibutyl phthalate, dioctyl phthalate, dioctyl adipate and dioctyl sebacate are used. Plasticizer is 10 per 100 parts by weight of styrene thermoplastic elastomer.
It is used in an amount of about 200 parts by weight, preferably 50 to 150 parts by weight. If the compounding amount is larger than this, outgas increases, and if the compounding amount is smaller than this, the sealing property is deteriorated, which is not preferable.

As the flaky inorganic filler, clay, diatomaceous earth, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxide, mica, graphite, aluminum hydroxide and the like are used. The flaky inorganic filler is 5 to 100 parts by weight of the styrene-based thermoplastic elastomer.
It is used in an amount of 100 parts by weight, preferably 10 to 70 parts by weight. If the blending amount is less than this, the moisture permeability becomes large, and the required function as a gasket cannot be satisfied, while if the blending amount is more than this, the hardness becomes high,
It will adversely affect the sealing property.

In the above composition, powdery solid fillers (for example, various metal powders, glass powders, ceramics powders, granular or powdery polymers, etc.) which are usually blended with rubber or thermoplastic elastomer as required. ), Anti-aging agents (eg amines and their derivatives, imidazoles,
Phenols and their derivatives), waxes, stabilizers, tackifiers, release agents, pigments, flame retardants, lubricants, etc. are used in combination.

In addition, a small amount of thermoplastic resin or rubber can be added to improve wear resistance and moldability. Furthermore, short fibers and the like can be added to improve strength and rigidity.

These blends are melt-kneaded using a heat kneader such as a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, a plavender, a kneader, and a high-shear type mixer, and further, if necessary, an organic compound. A cross-linking agent such as peroxide, a cross-linking auxiliary agent, or the like is added, or these necessary components are mixed at the same time and kneaded by heating, but a thermoplastic material obtained by kneading a polymer organic material and a softening agent is prepared in advance. It is also possible to prepare and further mix this material with one or more polymeric organic materials of the same or different types as used herein.

The styrene thermoplastic elastomer compound thus obtained is molded by injection into a mold having a metal cover coated with an adhesive. The metal cover may be an aluminum plate, a plated aluminum plate, a stainless steel plate, or a stainless steel damping steel plate, and the adhesive may be a maleic anhydride on the side chain of a polyolefin resin. Acid or acrylic acid grafted and modified with a polar group dissolved in an aromatic or aliphatic organic solvent and liquefied, or a dispersion or styrene-butadiene rubber that is aromatic or aliphatic The one which is liquefied by being dissolved in the organic solvent is used. If an adhesive is not used, peeling occurs during molding, and integral molding cannot be performed. As a method of applying the adhesive,
Dip coating, spray coating, screen printing, brush coating,
An optimal method such as a stamp method is selected as needed.

The hardness of the formed gasket rubber material (JIS
Durometer type A) is adjusted to 10-70. If the hardness is higher than this, the reaction force when the cover-integrated gasket is assembled to the main body becomes large, the cover is deformed, etc., and the seal cannot be completely sealed, and the sealing property as the gasket becomes poor. On the other hand, if it is less than this, the gasket has a tendency to be torn or easily sticks, so that care must be taken in handling.

[0019]

EFFECTS OF THE INVENTION By using the method for manufacturing the cover integrated gasket for a hard disk drive according to the present invention,
A gasket material for a hard disk drive, which has excellent sealing properties, low outgassing properties, moisture permeability, adhesive properties, moldability, and high dust resistance, can be easily prepared.

[0020]

EXAMPLES The present invention will now be described with reference to examples.

Example 1 Styrene-based thermoplastic elastomer compound 100 parts by weight of styrene-based thermoplastic elastomer (Kuraray product Septon 2006 [SEPS]) Polypropylene resin (Idemitsu Kosan J700GP) 25 〃 Paraffin oil 120 〃 (Idemitsu Kosan Diana Process oil PW380) Using a flaky inorganic filler (Hikawa industrial product Hikawa Mica) 50 〃 in a twin-screw extruder (Kobe Steel Co., Ltd. Hyper KTX46) at a set temperature of 210-180 ° C and a rotational speed of 150 rpm. I went.

About this compound, an injection molding machine
(Kawaguchi Tekko KM-80) was used to mold a test sheet (150 x 150 x 2 mm) at a set temperature of 210-180 ° C, injection speed of 0.5 sec, injection pressure of 100 Mpa, and cycle time of 30 seconds, and hardness, outgassing, Used for humidity permeability test. In addition, insert a part in which a modified olefin resin adhesive (Mitsui Chemicals Unistall R-300) is applied to an aluminum plate (electroless nickel plating 2 to 5 μm treatment) attached to the cover shape in advance, and insert it into the mold. Similarly, a gasket was molded on the cover at an injection speed of 0.3 sec, an injection pressure of 30 Mpa, and a cycle time of 30 seconds, and the cover-integrated gasket obtained was subjected to a sealability test, an adhesion test, and a moldability evaluation.

Example 2 In Example 1, Kuraray product Septon 4055 [SEEPS] was used in the same amount as the styrene thermoplastic elastomer.

Example 3 The polypropylene resin used in Example 1 was changed to 50 parts by weight.

Example 4 In Example 1, the paraffinic oil was changed to 180 parts by weight and used.

Example 5 In Example 1, the flaky inorganic filler was changed to 80 parts by weight and used.

Example 6 In Example 1, a styrene-butadiene rubber adhesive (Nogawa Chemical product, Diabond DA3188) was used instead of the modified olefin resin adhesive.

The measurement of each item using the gasket integrated with the test sheet and the cover obtained in each example was performed as follows. Hardness: JIS K6253 compliant (three test sheets are overlaid) Sealability test: A gasket integrally molded on the cover is mounted on the actual leak tester, and a positive pressure of 1.5 kPa is continuously applied for 30 seconds from inside the tester. Those that did not leak after 2 seconds were rated as ○, and those that leaked were rated as × (leaks if the gasket material has poor compression set characteristics or defective gasket shape) Outgassing test: 50 × 3 × 2 mm After heat-extracting a strip-shaped test sheet at 120 ° C for 1 hour, measure the outgas amount and
Those showing an outgas amount of less than g / g are evaluated as ○, and those showing an outgas amount (50 μg / g or more) are evaluated as × (A gasket showing an outgas amount of 50 μg / g or more is not suitable as a gasket for hard disk) Test: Cylindrical SUS container (inner diameter 27 mm, depth 50 m
(10 m) of distilled water in (m), sandwich a test sheet adjusted to a diameter of 30 mm and a thickness of 1 mm, and put a hollow lid made of SUS (inner diameter of the opening 27
mm) and calculate the water vapor transmission coefficient (g ・ mm / cm ² 24H) from the data after 70 ° C and 100 hours, and calculate 5 × 10 ^-3 (g ・ mm / cm ² 24H).
The value less than (H) is ○, 5 × 10 ^-3 (g ・ mm / cm ² 24H)
Those with the above values were evaluated as x (water vapor permeability coefficient of 5
* 10 ^-3 or more is not suitable as a gasket for hard disk) Adhesion test: About 1 mm of penetrating peeling is made on the gasket adhesive surface integrated with the cover, and a SUS wire is passed through that area to apply a vertical tensile load. Measure the load when the peeling length expands to about 10 mm, and those with a peeling load of 100 kPa or more are evaluated as ○, and those with a peeling load of less than this are evaluated as × (A peeling load of 100 kPa or more is sufficient even in the actual use environment. Adhesive strength) Moldability evaluation: Deformation, sink mark, chip, weld,
The ones that had no defects such as the occurrence of short shots and burrs, and the phenomenon that the cover could not be integrally molded were rated as ○, and those that had such defects were rated as ×.

The results obtained in each of the above examples are shown in Table 1 below.
Shown in. Table 1 Example 1 2 3 4 5 6 hardness (durometer type A) 47 46 61 35 52 47 Sealability ○ ○ ○ ○ ○ ○ Outgassing ○ ○ ○ ○ ○ ○ Humidity permeability ○ ○ ○ ○ ○ ○ Adhesion ○ ○ ○ ○ ○ ○ Moldability ○ ○ ○ ○ ○ ○

Comparative Example 1 In Example 1, the polypropylene resin was changed to 5 parts by weight and used.

Comparative Example 2 In Example 1, the polypropylene resin was changed to 110 parts by weight and used.

Comparative Example 3 The process oil used in Example 1 was changed to 5 parts by weight.

Comparative Example 4 The process oil used in Example 1 was changed to 220 parts by weight.

Comparative Example 5 In Example 1, the flaky inorganic filler was changed to 20 parts by weight and used.

Comparative Example 6 In Example 1, the flaky inorganic filler was changed to 120 parts by weight and used.

The results obtained in each of the above comparative examples are shown in Table 2 below.
Shown in. Table 2 Comparative Example 1 2 3 4 5 6 Hardness (Durometer type A) 43 72 76 28 42 57 Sealability ○ × × ○ ○ ○ Outgassing ○ ○ ○ × ○ ○ Humidity permeability ○ ○ ○ ○ × ○ Adhesion ○ ○ ○ ○ ○ ○ Formability × ○ ○ ○ ○ ×

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 23/16 C08L 23/16 53/00 53/00 91/00 91/00 G11B 33/12 313 G11B 33 / 12 313T // B29K 19:00 B29K 19:00 23:00 23:00 25:00 25:00 105: 16 105: 16 509: 00 509: 00 (72) Inventor Atsushi Koga Tsujido Shinmachi, Fujisawa City, Kanagawa Prefecture 4-3-1 F-term in NOK Co., Ltd. (reference) 4F206 AA11K AA13K AB07 AB11 AB16 AD03 AD27 AH13 AH42 JA07 JB12 4J002 AE05Y BB12X BB14X BB15X BP03W DA027 DE147 DE237 DG047 DJ037 DJ047 DJ057 FD02570017 FA017D EH096 E017.

Claims (4)

[Claims] 1. A mold having an adhesive-coated metal cover inserted therein, and 10 to 100 parts by weight of a polypropylene resin, 10 to 200 parts by weight of a plasticizer, and scaly inorganic filler per 100 parts by weight of a styrene thermoplastic elastomer. A method for manufacturing a gasket integrated with a cover for a hard disk drive, which comprises injecting 30 to 100 parts by weight of a styrene-based thermoplastic elastomer compound. 2. The method for producing a gasket integrated with a cover for a hard disk drive according to claim 1, wherein the styrene-based thermoplastic elastomer is a polystyrene-poly (ethylene-propylene) -polystyrene block copolymer. 3. The method for producing a cover-integrated gasket for a hard disk drive according to claim 1, wherein the styrene-based thermoplastic elastomer is a polystyrene-poly (ethylene / ethylene-propylene) -polystyrene block copolymer. 4. The hardness (JIS Durometer type A) is 10
A hard disk drive integrated cover gasket manufactured by the method according to claim 1, wherein the gasket of 70 to 70 is formed.