JP2000257719A - Gasket with frame and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the mechanical strength and electromagnetic wave shielding property of a gasket, and reduce the weight thereof by unifying a framework made of the synthetic resin with the gasket made of an elastic material and forming a cross section of the frame into a deformed shape. SOLUTION: As the synthetic resin forming a frame 1, a thermoplastic resin such as styrene resin such as acrylonitrile styrene resin, olefin resin such as polyethylene, polyamide resin such as nylon, and polyester resin such as polyethylene terephthalate is used. The frame 1 is formed into a shape having a different cross section in surfaces vertical to the inner periphery and outer periphery of the frame. A gasket with frame is used for bonding surfaces of a cover body 4 and a box body 4. On a point of the electromagnetic shielding property, an H-type frame is desirable. As an elastic body forming the gasket and members, vulcanized rubber and thermoplastic elastomer can be used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gasket with a frame and a method of manufacturing the same, and more particularly, to a gasket with a frame for sealing a joint surface between a cover body and a main body of a lightweight electronic device, for example, a hard disk device of a computer. It relates to the manufacturing method. The gasket with a frame according to the present invention has improved strength and electromagnetic wave shielding properties of the frame, and is used for completely sealing technology from water or air such as a hard disk device of a computer installed in a robot in an automation line or the like. Applicable.

[0002]

2. Description of the Related Art In recent years, the development of electronic devices has been remarkable. These electronic devices use integrated circuits using semiconductors and are printed and wired on a substrate.
The weight has been reduced. These electronic devices dislike moisture and dust. Therefore, the sealing performance of the gasket that seals the joint surface between the box-shaped main body containing these integrated circuits and the cover body depends on the performance and durability of the electronic devices. Is an important factor for

[0003] Therefore, usually, a gasket is sandwiched between the joint surfaces of a box body and a cover body containing these integrated circuits and the like, and the gasket is fastened with mounting bolts or the like to be hermetically integrated. A high-density urethane foam material was used as the material. The urethane foam material is foamed into a thin sheet shape, and an adhesive tape is stuck to the sheet and punched into a desired shape in many cases. Further, there has been proposed a gasket in which an elastomer is fixed to both surfaces of a frame, which is manufactured by inserting a frame made of stainless steel or a synthetic resin into a mold and then injection-molding an elastomer (Japanese Patent Laid-Open No. 8-2836).
No. 98). This gasket has a gasket having rigidity by employing a frame, and has improved mountability to equipment.

When a gasket with a frame having an elastomer fixed to both surfaces of a frame is used while being sandwiched between joint surfaces of the box and the cover, the gasket is provided at several flat portions of a predetermined height provided on the box. The cover and the cover are crushed by abutment, and the gasket where the box and the cover are not abutted is crushed, thereby sealing the box and the cover. The amount of crushing of the gasket at a location where the box and the cover do not abut each other is determined by the height of the flat portion provided on the box. In storing electronic devices, it is important that the storage container has an electromagnetic wave shielding property. However, in a place where the box body and the cover body do not abut, as shown in FIG. is there. That is, FIG. 2 is a gasket with a frame having a cross section shown in FIG.
This corresponds to a cross section along the line AA shown in FIG. ) Is used at the joint surface between the cover body 3 and the box body 4, but it can be seen that the electromagnetic wave shielding properties are not sufficient at places where the box body and the cover body do not abut. In order to impart electromagnetic wave shielding to the framed gasket of such a form, a conductive material is blended with the gasket material,
A method of forming a highly conductive gasket by molding this can be considered. However, if a large amount of conductive material is added to the gasket material in order to obtain a sufficient electromagnetic wave shielding property, the flowability of the gasket material increases and molding becomes difficult, so that this method is not practical. Therefore, at present, it is difficult to obtain a framed gasket having excellent electromagnetic wave shielding characteristics. Further, the shape of the frame in the conventional gasket with a frame is a flat plate shape, but when such a frame is manufactured by punching or press forming a metal plate, from the viewpoint of ensuring sufficient strength of the frame. It was necessary to set the thickness of the frame in accordance with the portion where the width of the frame was the smallest, and thus the weight of the frame could not be avoided.

[0005]

DISCLOSURE OF THE INVENTION The present invention is superior in mechanical strength and electromagnetic wave shielding property as compared with a flat frame,
Another object of the present invention is to provide a lightweight gasket with a frame.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, the shape of the frame in the framed gasket has been changed at the outer periphery and / or inner periphery of the frame. By making the shape with ribs perpendicular to the body plane, the strength against bending becomes larger than the flat frame, and the electromagnetic wave shielding property is also improved, and by forming the frame with synthetic resin, The present inventors have found that a gasket with a frame that satisfies the requirements of bending strength, electromagnetic wave shielding properties, and weight reduction can be obtained as compared with a frame made of a metal plate such as stainless steel. The present invention has been completed based on such findings. That is, the present invention provides a gasket with a frame in which the frame and the gasket are integrated, wherein the frame is made of a synthetic resin, the gasket is made of an elastic body, and the cross section of the frame has an irregular shape. And a method of manufacturing the above-mentioned gasket with a frame, wherein the framed gasket and the frame body and the gasket are integrated by a two-color molding method or an insert molding method.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the gasket with a frame of the present invention, the synthetic resin forming the frame is, for example, acrylonitrile styrene (AS) resin, acrylonitrile butadiene styrene (ABS) resin, styrene such as polystyrene and syndiotactic polystyrene. Resin, olefin resin such as polyethylene and polypropylene,
Examples thereof include polyamide resins such as nylon, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, and thermoplastic resins such as modified polyphenylene ether, acrylic resin, polyacetal, and polycarbonate, which may be appropriately selected from these. These resins may be used alone or in combination of two or more. The shape of the frame is such that its cross section in a plane perpendicular to the inner and outer circumferences of the frame has an irregular shape, and specific examples thereof include an H-shape and a T-shape. Referring to FIGS. 3 to 5, FIG. 3 is a perspective view of a gasket with a frame of the present invention, and a cross section of the gasket with a frame taken along line AA of FIG. 4 is a cross-sectional view shown in FIG. The cross section of the body 1 has an H shape. FIG. 5 shows a state in which the gasket with a frame shown in FIGS. 3 and 4 is used at the joint surface between the cover body 3 and the box body 4. 6 to 9 also show cross-sectional views similar to FIG. 5, FIGS. 6 and 7 show examples of the H type, and FIGS. 8 and 9 show examples of the T type. The frame 1 shown in FIG. 5 and FIG. 6 is one in which the inside of the H shape is formed in a straight line, and the frame 1 shown in FIG.
Is a taper provided inside the H-shape. The frame having a T-shaped cross section shown in FIGS. 8 and 9 has the rib 5 positioned outside the cover 3 and the box 4.
May be located inside. As shown in FIGS. 5 and 8, the rib 5 and the cover 3 and the box 4 may have the same overall width of the H-type or T-type and the width of the cover 3 and the box 4. As shown in FIGS. 7 and 8, the width of the inside of the H-type or T-type may be the same as the width of the cover 3 and the box 4. In the present invention, from the viewpoint of electromagnetic shielding properties,
The shape of the frame is preferably H-shaped. The thickness of the frame 1 and the height of the ribs 5 are appropriately selected according to the use of the gasket with a frame, and the thickness of the frame is usually 0.3 to 1.0 mm, preferably 0.4 to 0.6 mm. Range. The height of the rib is usually in the range of 0.5 to 1.5 mm, preferably 0.6 to 1.0 mm.

Further, as the elastic body forming the gasket or the member, vulcanized rubber such as butyl rubber or EPDM rubber, thermoplastic elastomer, or the like can be used. As the thermoplastic elastomer, for example, a thermoplastic elastomer such as a styrene-based, olefin-based, urethane-based, or ester-based thermoplastic elastomer can be used. In particular, at least one of a polymer block mainly composed of a vinyl aromatic compound and a conjugated diene compound are used. Those containing a thermoplastic elastomer of a copolymer composed of at least one of the main polymer blocks are preferably used. More specifically, for example, a block copolymer of crystalline polyethylene and ethylene / butylene-styrene random copolymer obtained by hydrogenating a block copolymer of polybutadiene and butadiene-styrene random copolymer, A block copolymer of polybutadiene and polystyrene, and a block copolymer of polyisoprene and polystyrene, or obtained by hydrogenating a block copolymer of polybutadiene or an ethylene-butadiene random copolymer and polystyrene, for example, Diblock copolymer of crystalline polyethylene and polystyrene, styrene
Ethylene / butylene-styrene triblock copolymer (SEBS), styrene-ethylene / propylene-styrene triblock copolymer (SEPS), etc.
Styrene-ethylene / butylene-styrene block copolymer or styrene-ethylene / propylene-styrene block copolymer. These elastomers are
They may be used alone or in combination of two or more. The combination of the thermoplastic resin of the frame and the thermoplastic elastomer which is the material of the gasket is not particularly limited, but a combination of an olefin resin and a styrene elastomer or an olefin elastomer, a nylon or ABS resin and a urethane elastomer And the like.

An antistatic property can be imparted to the thermoplastic resin or thermoplastic elastomer by adding a filler capable of imparting conductivity. By imparting antistatic properties, it is possible to prevent dust and dirt from adhering to the gasket and the cover body in the manufacturing process of the cover with the gasket. Examples of the filler capable of imparting conductivity include conductive powders such as metal powder and metal fiber such as iron, stainless steel and aluminum, carbon black and carbon fiber, polyalkylamine, alkylsulfonate, and the like.
Antistatic agents such as quaternary ammonium chloride and alkyl betaine can be used. The addition amount of the filler to the thermoplastic resin or the thermoplastic elastomer is, from the viewpoint of imparting electromagnetic shielding properties, the volume resistance of the thermoplastic resin or the thermoplastic elastomer when the filler is added is 1 ×
It is preferable that the amount is 10 ² Ωcm or less. Further, in the thermoplastic elastomer, the JIS-A hardness when the filler is added is 80 degrees or less, particularly 10 to 50 degrees.
Degree is preferable. Further, the above-mentioned thermoplastic resin or thermoplastic elastomer includes, as reinforcing materials, inorganic fibers such as glass fibers and carbon fibers, inorganic fillers such as mica and talc, and whiskers such as potassium titanate.
It can be added in a range that does not impair the effects of the present invention.

The integration of the frame and the gasket is performed by joining a thermoplastic resin forming the cover with a thermoplastic elastomer forming the gasket, and specifically, such as a two-color molding method and an insert molding method. Done by the method. In the two-color molding method, first, a thermoplastic resin forming the frame is melt-injected and molded into a mold by a dedicated injection molding machine to obtain a frame of a thermoplastic resin molded product having a fitting portion.
Then, after the molded product is solidified, the thermoplastic elastomer having excellent fusion property with the thermoplastic resin is melt-injected and molded by a dedicated injection molding machine, and the fitting portion of the frame of the thermoplastic resin molded product is formed. By forming a gasket portion made of a thermoplastic elastomer layer in a portion other than the above, a gasket with a frame in which a thermoplastic resin and a thermoplastic elastomer layer formed on the surface thereof are integrally integrated is obtained. Such a two-color molding method has a high production efficiency and can produce a framed gasket at low cost. On the other hand, in the insert molding method, a frame having a predetermined shape is prepared by a known various molding method using a thermoplastic resin in advance, and the frame is placed in a mold. Next, the thermoplastic elastomer is melt-injected and molded by an injection molding machine to form a thermoplastic elastomer layer on a part of the frame, thereby forming the frame and the thermoplastic elastomer formed on the part thereof. Are integrally combined to obtain a framed gasket.

Since the framed gasket of the present invention uses a synthetic resin as a material of the frame and does not use a metal material, it does not require a rust-proofing step and can be reduced in weight. It can be suitably used. Further, the shape in which the ribs are provided on the frame cannot be obtained by punching or press molding a metal plate, but is obtained by injection molding using a synthetic resin. Furthermore, since the synthetic resin is used, it is possible to manufacture the frame body at a low cost, efficiently and with high precision using one mold, and to recycle the synthetic resin. Examples of the material for forming the cover or box in which the framed gasket of the present invention is used include the above-mentioned thermoplastic resins and other various synthetic resins, and other metals or alloys such as aluminum, iron, stainless steel, and magnesium. Can be used.

[0012]

Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. Example 1 FIG. 3 is a perspective view of a gasket with a frame of the present invention, FIG. 4 is a cross-sectional view taken along line AA of FIG. 3, and FIG. 5 is a view showing a use state of the gasket with a frame. This gasket with a frame has a thickness of 1.5 mm (the total height of the gasket with a frame shown in FIG. 4 is 1.5 mm), and the width of the frame 1 is 2.0 mm.
The thickness of the frame 1 is 0.4 mm, and the height of the rib 5 is 0.8 mm. In FIG. 5, 3 is a cover, and 4 is a box. This framed gasket was produced by a two-color molding method as follows. As the thermoplastic resin forming the frame 1, short glass fiber reinforced 30% polypropylene (Noblen GHH43, manufactured by Sumitomo Chemical Co., Ltd.) was used. The thermoplastic elastomer forming the gasket is composed of 100 parts by weight of SEPS having a number average molecular weight of 100,000 and a styrene content of 30% by weight, and a kinematic viscosity at 40 ° C. of 380 mm ² / sec.
Paraffin oil [manufactured by Idemitsu Kosan Co., Ltd., trade name: Diana Process Oil PW380, number average molecular weight 75]
0] 150 parts by weight and 12.5 parts by weight of polypropylene (Noblen Y101, manufactured by Sumitomo Chemical Co., Ltd.) were prepared by kneading. The JIS-A hardness of this thermoplastic elastomer was 22 degrees. Using a DC60E5ASE machine manufactured by Nissei Plastics Co., Ltd. as a molding machine, first, the thermoplastic resin for a frame was melt-injected and molded into a mold under the conditions of a mold temperature of 40 ° C. and a resin temperature of 180 ° C. The weight of the obtained frame was 0.45 g. Next, the thermoplastic elastomer for a gasket was melt-injected and molded on the frame under the conditions of a mold temperature of 40 ° C. and a resin temperature of 230 ° C., thereby producing a gasket with a frame in which the frame and the gasket were integrated. . The weight of the obtained gasket with frame is 1.2
It was 5 g. The weight of the framed gasket of Comparative Example 1 was 1.8 g (the weight of the frame was 1.0 g).
Therefore, the weight can be reduced by 50% or more. Further, the bending strength of the gasket with a frame was equivalent to that of the gasket with a frame of Comparative Example 1. Comparative Example 1 A flat plate made of stainless steel having a thickness of 0.13 mm was used as the frame body 1, and the same thermoplastic elastomer as that used in Example 1 was used as the thermoplastic elastomer forming the gasket, and the total height including the gasket was used. Produced a 1.5 mm framed gasket. The width of the frame body of this gasket with a frame is the same as in Example 1.
0 mm. This framed gasket was produced by the insert molding method as follows. The above-mentioned stainless steel frame was converted to TH30R5 manufactured by Nissei Plastics Industry Co., Ltd.
By inserting the above-mentioned thermoplastic elastomer for a gasket into a mold attached to a VSE machine at a mold temperature of 50 ° C. and a resin temperature of 200 ° C. by injection molding,
A gasket with a frame in which the frame and the gasket were integrally integrated was produced.

[0013]

The gasket with a frame of the present invention has a flexural strength,
It satisfies the requirements of electromagnetic wave shielding and lightening, and is excellent in sealing.

[Brief description of the drawings]

FIG. 1 is a sectional view of a conventional gasket with a frame.

FIG. 2 is a partially cutaway sectional view showing a usage form of the framed gasket shown in FIG.

FIG. 3 is a perspective view of the framed gasket of the present invention.

4 is a cross-sectional view of the framed gasket shown in FIG. 3 taken along line AA.

FIG. 5 is a partially cutaway sectional view showing a use form of the framed gasket shown in FIG. 4;

FIG. 6 is a partially cutaway sectional view showing a use form of the framed gasket of the present invention.

FIG. 7 is a partially cutaway sectional view showing a usage form of the framed gasket of the present invention.

FIG. 8 is a partially cutaway sectional view showing a use form of the framed gasket of the present invention.

FIG. 9 is a partially cutaway sectional view showing a usage form of the framed gasket of the present invention.

[Explanation of symbols]

 1: frame 2: gasket 3: cover 4: box 5: rib

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3J040 AA01 AA11 BA01 EA15 EA17 EA25 EA50 FA05 HA01 HA09 4E360 AA02 AB12 AB33 AB51 EE03 GA11 GA23 GA29 GA34 GA52 GB43 GC08 4F206 AA11 AA45 AB25 AH13 JA07 JB12 BB03 BB33 BB33 GH07

Claims (7)

[Claims] 1. A gasket with a frame in which a frame and a gasket are integrated, wherein the frame is made of a synthetic resin, the gasket is made of an elastic material, and the cross section of the frame has an irregular shape. Gasket with frame. 2. The gasket with a frame according to claim 1, wherein the irregular shape is an H-shaped shape or a T-shaped shape. 3. The gasket according to claim 1, wherein the frame is made of a thermoplastic resin. 4. The framed gasket according to claim 1, wherein the elastic body forming the gasket is a thermoplastic elastomer. 5. The gasket with a frame according to claim 4, wherein the integration is performed by fusing a thermoplastic resin forming the frame with a thermoplastic elastomer forming the gasket. 6. A method of manufacturing a gasket with a frame, comprising: integrating a frame and a gasket by a two-color molding method to manufacture the gasket with a frame according to any one of claims 1 to 5. 7. A method for producing a gasket with a frame, comprising: integrating the frame and the gasket by insert molding to produce the gasket with a frame according to any one of claims 1 to 5.