U.S. patent application number 10/015785 was filed with the patent office on 2002-05-02 for gasketed cover, cover for electronic equipment and process for producing the covers.
This patent application is currently assigned to Bridgestone Corporation. Invention is credited to Machida, Kunio, Nishimuro, Youichi, Toyosawa, Shinichi.
Application Number | 20020050692 10/015785 |
Document ID | / |
Family ID | 27290667 |
Filed Date | 2002-05-02 |
United States Patent
Application |
20020050692 |
Kind Code |
A1 |
Nishimuro, Youichi ; et
al. |
May 2, 2002 |
Gasketed cover, cover for electronic equipment and process for
producing the covers
Abstract
There are disclosed a first gasketed cover which has excellent
sealing properties and comprises a cover body composed of a
thermoplastic resin and a gasket composed of a thermoplastic
elastomer and integrated with the cover body; a second gasketed
cover which has excellent sealing properties and is capable of
preventing the generation of noises due the vibration of the cover
and which comprises a cover body, a gasket composed of an elastic
body and integratedly attached to the cover body, and a member
composed of the elastic body of a type same as or different from
that in the gasket and integratedly installed on at least part of
the cover body plane portion excluding the gasket portion; an
electronic equipment cover which is capable of preventing pressure
difference between the inside and the outside thereof and which
comprises a cover body and a membrane composed of an elastic body
and installed on a hole placed on the plane portion of the cover
body, in which the cover body is integrated with the membrane; and
processes for producing the first and second gasketed covers and
the electronic equipment cover each by any of two-color molding
method and inserting molding method.
Inventors: |
Nishimuro, Youichi;
(Kunitachi-shi, JP) ; Toyosawa, Shinichi;
(Tokorozawa-shi, JP) ; Machida, Kunio;
(Suginami-ku, JP) |
Correspondence
Address: |
OBLON SPIVAK MCCLELLAND MAIER & NEUSTADT PC
FOURTH FLOOR
1755 JEFFERSON DAVIS HIGHWAY
ARLINGTON
VA
22202
US
|
Assignee: |
Bridgestone Corporation
10-1, Kyobashi 1-chome
Chuo-ku
JP
|
Family ID: |
27290667 |
Appl. No.: |
10/015785 |
Filed: |
December 17, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10015785 |
Dec 17, 2001 |
|
|
|
09427984 |
Oct 27, 1999 |
|
|
|
Current U.S.
Class: |
277/650 |
Current CPC
Class: |
H05K 5/061 20130101;
F16F 9/526 20130101; H05K 5/03 20130101 |
Class at
Publication: |
277/650 |
International
Class: |
F16J 015/08 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 1998 |
JP |
10-309945 |
Feb 19, 1999 |
JP |
11-040989 |
Feb 19, 1999 |
JP |
11-040990 |
Claims
What is claimed is:
1. A gasketed cover comprising a cover body which is composed of a
thermoplastic resin and a gasket which is composed of a
thermoplastic elastomer, said cover body being fitted with said
gasket and integrated therewith.
2. The gasketed cover according to claim 1, wherein the
thermoplastic resin which constitutes the cover body is integrated
with the thermoplastic elastomer which constitutes the gasket by
means of fused adhesion therebetween.
3. The gasketed cover according to claim 1, wherein the
thermoplastic resin is incorporated with a filler capable of
imparting electroconductivity thereto, and said thermoplastic resin
incorporated with a filler has a volume resistivity of at most
1.times.10.sup.8 .OMEGA.cm.
4. The gasketed cover according to claim 1, wherein the
thermoplastic resin is incorporated with a filler capable of
imparting electroconductivity thereto, and said thermoplastic resin
incorporated with a filler has a volume resistivity of at most
1.times.10.sup.8 .OMEGA.cm and a JIS hardness-A of at most 80
degrees.
5. The gasketed cover according to claim 1, wherein the
thermoplastic resin which constitutes the cover body comprises a
liquid crystal polymer or polyphenylene sulfide resin.
6. A process for producing the gasketed cover as set forth in claim
1, which comprises integrating the cover body with the gasket by
means of a two-color molding method.
7. A process for producing the gasketed cover as set forth in claim
1, which comprises integrating the cover body with the gasket by
means of an inserting molding method.
8. A gasketed cover comprising a cover body; a gasket which is
composed of an elastic body and integratedly attached to said cover
body; and a member which is composed of the elastic body of a type
same as or different from that of the gasket and integratedly
installed on at least part of the plane portion of the cover body
excluding the gasket portion.
9. The gasketed cover according to claim 8, wherein the elastic
body which constitutes the gasket is composed of a thermoplastic
elastomer.
10. The gasketed cover according to claim 8, wherein the cover body
is composed of a thermoplastic resin.
11. The gasketed cover according to claim 10, wherein the
thermoplastic resin which constitutes the cover body is integrated
with the elastic body by means of fused adhesion therebetween, said
elastic body constituting the gasket and the member which is
composed of the elastic body of a type same as or different from
that of the gasket.
12. A process for producing the gasketed cover as set forth in
claim 9, which comprises integratedly shaping the gasket and the
member which is composed of the elastic body of a type same as or
different from that of the gasket onto the cover body by means of
an injection molding method.
13. A process for producing the gasketed cover as set forth in
claim 10, which comprises integrating the cover body with the
gasket and the member which is composed of the elastic body of a
type same as or different from that of the gasket by means of a
two-color molding method.
14. A process for producing the gasketed cover as set forth in
claim 10, which comprises integrating the cover body with the
gasket and the member which is composed of the elastic body of a
type same as or different from that of the gasket by means of an
inserting molding method.
15. An electronic equipment cover comprising a cover body and a
membrane which is composed of an elastic body and is installed on a
hole placed on the plane portion of the cover body, said cover body
and said membrane being integrated with each other.
16. The electronic equipment cover according to claim 15,
comprising a cover body and a membrane which is composed of an
elastic body and is installed on a hole placed on the plane portion
of the cover body, said cover body and said membrane being
integrated by that the peripheral portion of said hole is
interposed between the outer peripheral portion of said
membrane.
17. The electronic equipment cover according to claim 15, which
further comprises a gasket which is composed of the elastic body of
a type same as or different from that of the membrane on the plane
portion of the cover body excluding the hole portion thereof, said
cover body and said gasket being integrated to constitute a
gasketed cover.
18. The electronic equipment cover according to claim 15, wherein
the cover body is composed of a thermoplastic resin.
19. The electronic equipment cover according to claim 15, wherein
the elastic body constituting the membrane is a thermoplastic
elastomer.
20. The electronic equipment cover according to claim 15, wherein
the elastic body constituting the gasket and the membrane is a
thermoplastic elastomer.
21. The electronic equipment cover according to claim 20, wherein
the thermoplastic resin which constitutes the cover body is
integrated with the elastic body which constitutes the gasket and
the member by means of fused adhesion therebetween, said member
being composed of the elastic body same as that of the gasket.
22. A process for producing the electronic equipment cover as set
forth in claim 15, which comprises integratedly shaping the
membrane onto the cover body by means of an injection molding
method.
23. A process for producing the electronic equipment cover as set
forth in claim 20, which comprises integrating the cover body, the
gasket and the membrane which is composed of the elastic body same
as that of the gasket by means of two-color molding method.
24. A process for producing the electronic equipment cover as set
forth in claim 20, which comprises integrating the cover body with
the gasket and the membrane which is composed of the elastic body
same as that of the gasket by means of an inserting molding method.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a gasketed cover which
hermetically seals the joint surface between a cover body and a
main body in lightweight equipment, for instance, hard disc
equipment of a computer; an electronic equipment cover; and
processes for the production of said covers. The gasketed cover and
an electronic equipment cover according to the present invention
are applied to techniques for hermetically sealing the hard disc
equipment of a computer installed inside a robot in an automatic
manufacturing line or the like so as to completely keep water and
air away therefrom.
[0003] The gasketed cover according to the present invention can
prevent a noise from being generated by the vibration of the cover
body at the time of using the gasketed cover. Moreover, the
electronic equipment cover according to the present invention can
prevent the difference in pressure from occurring between the
inside and the outside of the box type main body at the time of
using the aforesaid cover.
[0004] 2. Description of the Related Arts
[0005] The development of electronic equipment in recent years
really amazes the persons concerned. The above-mentioned equipment,
especially integrated circuits which utilizes semiconductors, such
as compactified lightweight hard disc equipment are prone to be
readily damaged by moisture or dampness in particular.
[0006] Accordingly, the hermetically sealing performance of a
gasket is a factor of importance for the performance and durability
of the electronic equipment, which gasket is used for hermetically
sealing the joint surface between a cover body and a box type main
body having built-in integrated circuits mentioned above.
[0007] It is customary for the purpose of hermetical sealing to
integrate a cover body and a box type main body having built-in
integrated circuits into equipment by interposing a gasket which
hermetically seals the joint surface between said both the bodies
and tightening them with fixing bolts. In general, the gasket is
adhesively attached to said cover body by means of a double coated
tape or the like, which gasket is placed on the joint surface
between said cover body and the main body, and interposed
therebetween.
[0008] The foregoing constitution, however, has often brought about
such troubles that long-term usage of the gasket in question lowers
the adhesive force of an adhesive coated onto the double coated
tape through degeneration, impairs the hermetically sealing
function thereof and at the same time, allows dust or moisture to
penetrate into the main body, thus unfavorably causing failure of
the electronic equipment.
[0009] The cover body is usually formed of a metal such as iron,
stainless steel and aluminum. The cover body made of a metal is
formed by a method in which any of a variety of metallic plates is
subjected to punching work or drawing work by the use of a
prescribed pressing mold to put the shape thereof in order, and
thereafter the worked metal is subjected to an anti-corrosion
treatment by non-electrolytic nickel plating, chromium plating,
zinc plating or the like.
[0010] In the case, however, where the cover body is formed of any
of the metals, various molds to be used for punching work or
drawing work are needed, and the method of working a metallic plate
for the cover body is limited to the above-mentioned working
method, whereby the shape of the cover body is restricted to
workable shapes. Hence, it is impossible to design the cover body
with intricate configuration such as installing a reinforcing rib
to enhance the rigidity of the cover body, reinforce only the
flange portion thereof and the like. In addition, the problem still
remains unsolved in that the heavy metals such as chromium and
nickel, which are used for anti-corrosion treatment indispensable
for a metal, involve a strong fear of causing environmental
destruction.
[0011] On the one hand, the gasket has heretofore been produced by
punching sheet-like high density polyurethane foam material into a
prescribed shape, and the material which is left after the punching
is mostly discarded as a waste material. The conventional procedure
just mentioned has involved the problems that the yield is worsened
thereby, and the gasket formed with said material has a relatively
large compression set, thus making it difficult to maintain the
hermetically sealing performance for a long period of time and
hence deteriorating the durability of the electronic equipment.
[0012] The above-mentioned problem relating to the compression set
was solved by the adoption of vulcanized rubber such as butyl
rubber and EPDM rubber as a material of construction for a gasket,
but the problem still remains unsolved in that an unreasonably long
time is required by vulcanization.
[0013] Accompanying the tendency of compactification and
light-weightness of hard disc drives in recent years, the cover
body of electronic equipment has been thin-walled. However, the
cover body, when formed with a thin-walled metal plate, increases
the vibrational frequency of resonance which is generated
accompanying the revolution of a spindle motor, thereby bringing
about the problem of noisy sound generated at the time of using a
hard disc drive. Notwithstanding said problem of noisy sound, no
countermeasure there against has been taken in the conventional
gasketed cover and cover body.
[0014] With regard to the integrated circuits in recent years which
make use of semiconductors such as a hard disc apparatus of a
compactified lightweight computer, the apparatus is airtightly
sealed inside to keep the inside environment constant. For
instance, the inside of a hard disc apparatus is airtightly sealed,
and thus the environment therein is kept constant by installing a
cover body on the main body of the apparatus. However under a
complete airtightly sealed condition, a box type main body of the
apparatus is often pressurized inside by the rotation of a hard
disc driven by a spindle motor, whereby the internal pressure
therein is increased. In the case where the apparatus is used under
a low temperature environment, the inside thereof is often brought
to negative pressure by the shrinkage of the atmosphere therein. In
any of the above-mentioned cases, there is caused pressure
difference between the inside and outside of the apparatus.
[0015] Such being the case, some contrivance has been made so as
not to cause the pressure difference therebetween by placing a
breathing hole at one portion of the main body of electronic
equipment so as to allow outside air to communicate with the space
in the main body. Nevertheless, since there is a danger that the
breathing hole allows the penetration of a gas and fine foreign
matter that are responsible for malfunction of a magnetic disc
caused by its accumulation thereon, it is regarded as being
necessary to equip the inside of the breathing hole with a dust
prevention filter and/or an adsorbent for said gas {refer to
Japanese Patent Application Laid-Open No. 36548/1994 (Heisei-6)}.
In addition, there is adopted a method in which the breathing hole
is slotted so as to prevent sudden change in the pressure inside
the main body {refer to Japanese Patent Application Laid-Open No.
297987/1997 (Heisei-9)}. Such breathing mechanism, although
effective in preventing the pressure difference from being caused
between the inside and outside of the apparatus, complicates the
production steps of the apparatus because of the intricate
mechanism, thereby unfavorably increasing the production cost.
SUMMARY OF THE INVENTION
[0016] Under such circumstances, it is a general object of the
present invention to provide a first gasketed cover which is
lightweight, excellent in sealing properties, and also efficiently
producible at a low cost in high precision and accuracy even for
intricate shapes without the need for a troublesome production
step.
[0017] It is another object of the present invention to provide a
second gasketed cover which is capable of preventing the generation
of noises due to the vibration of a cover body, and excellent in
sealing properties.
[0018] It is still another object of the present invention to
provide an electronic equipment cover which is capable of
preventing pressure difference from being caused between the inside
and the outside of the main body of the above-mentioned electronic
equipment with an inexpensive mechanism without placing a
complicated breathing mechanism when pressure variation is caused
inside or outside the main body thereof.
[0019] Other objects of the present invention will be obvious from
the text of the specification hereinafter disclosed.
[0020] In view of the above, intensive extensive research and
investigation were accumulated by the present inventors in order to
achieve the above-mentioned objects. As a result, it has been found
that the general object can been achieved by forming a cover body
with a thermoplastic resin and at the same time, forming a gasket
with a thermoplastic elastomer so as to prepare a gasketed cover in
which the cover body is fitted with a gasket.
[0021] It has also been found that the object of preventing the
generation of noises due to the vibration of the cover body can
been achieved by integratedly installing at least one member
composed of the elastomer same as that of the gasket on at least
part of the plane portion of the cover body excluding the gasket
portion so as to prepare a gasketed cover in which the cover body
is fitted with a gasket.
[0022] It has further been found that the object of eliminating the
pressure difference between the inside and the outside of the body
of electronic equipment can been achieved by integratedly
installing a membrane composed of an elastomer on the plane portion
of the cover body so that pressure variation, when being caused
inside or outside thereof, can be absorbed by the expansion of said
membrane towards inside or outside.
[0023] It being so, the present invention has been accomplished by
the above-mentioned findings and information.
[0024] Specifically, the present invention provides a first
gasketed cover comprising a cover body which is composed of a
thermoplastic resin and a gasket which is composed of a
thermoplastic elastomer, said cover body being fitted with said
gasket and integrated therewith.
[0025] Further, the present invention provides a second gasketed
cover comprising a cover body; a gasket which is composed of an
elastic body and integratedly attached to said cover body; and a
member which is composed of the elastic body of a type same as or
different from that of the gasket and integratedly installed on at
least part of the plane portion of the cover body excluding the
gasket portion. Further, the present invention provides an
electronic equipment cover comprising a cover body and a membrane
which is composed of an elastomer and is installed on a hole placed
on the plane portion of the cover body, said cover body and said
membrane being integrated with each other.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] FIG. 1 is a cross sectional view showing a first gasketed
cover according to the present invention;
[0027] FIG. 2 is a perspective illustration which shows the
gasketed cover as shown in FIG. 1, and which is viewed from the
sealing surface side;
[0028] FIG. 3 is an another cross sectional view showing a first
gasketed cover according to the present invention;
[0029] FIG. 4 is a perspective illustration which shows a second
gasketed cover according to the present invention, and which is
viewed from the sealing surface side;
[0030] FIG. 5 is a perspective illustration which shows an
electronic equipment cover according to the present invention, and
which is viewed from the sealing surface side; and
[0031] FIG. 6 is a cross sectional view which shows the electronic
equipment cover as shown in FIG. 5 and which is taken on line A-A'
of FIG. 5.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0032] The thermoplastic resin which constitutes the cover body in
the first gasketed cover according to the present invention may be
properly selected from among acrylonitrile styrene (AS) resin,
acrylonitrile butadiene styrene (ABS) resin, styrenic resin such as
polystyrene and syndiotactic polystyrene, olefinic resin such as
polyethylene and polypropylene, polyamide resin such as nylon,
polyester based resin such as polyethylene terephthalate and
polybutylene terephthalate, modified polyphenylene ether, acrylic
resin, polyacetal, polycarbonate, a liquid crystal polymer,
polyphenylene sulfide (PPS) and the like. The liquid crystal
polymer is preferably a thermotropic liquid crystal polymer, which
is classified into those of polycarbonate base, polyurethane base,
polyamide base, polyester base and the like, respectively. Of
these, the polyester-base liquid crystal polymer is preferable in
the present invention. Any one of the above-exemplified
thermoplastic resins may be used alone or in combination with at
least one other resin mentioned above.
[0033] In regard to the thermoplastic elastomer constituting the
gasket according to the present invention, there are usable
styrenic, olefinic, urethane based and ester based thermoplastic
elastomers, of which is preferably usable in particular the
copolymer comprising at least one polymer block composed
principally of a vinylic aromatic compound and at least one polymer
block composed principally of a conjugated diene compound.
[0034] More specific examples of said elastomers include:
[0035] {circle over (1)} Block copolymer of crystalline
polyethylene and ethylene/butylene styrene random copolymer, said
block copolymer being obtained by hydrogenating block copolymer of
polybutadiene and butadiene-styrene random copolymer; and
[0036] {circle over (2)} Block copolymer of polybutadiene and
polystyrene, block copolymer of polyisoprene and polystyrene,
diblock copolymer of crystalline polyethylene and polystyrene, said
diblock copolymer being obtained by hydrogenating block copolymer
of polybutadiene or ethylene-butadiene random copolymer and
polystyrene, triblock copolymer (SEBS) of
styrene-ethylene/butylene-styrene, and triblock copolymer (SEPS) of
styrene-ethylene/propylene-styrene, in particular, block copolymer
of styrene-ethylene/butylene-styrene, and block copolymer of
styrene-ethylene/ propylene-styrene. Any one of the
above-exemplified thermoplastic elastomers may be used alone or in
combination with at least one other elastomer mentioned above.
[0037] No specific restriction is imposed upon the combination of
the thermoplastic resin as a material of the cover body and the
thermoplastic elastomer as a material of the gasket. There are
exemplified the combination of olefinic resin and styrenic
elastomer or olefinic elastomer, the combination of nylon or ABS
resin and urethane based elastomer, and the like.
[0038] The thermoplastic resin or the thermoplastic elastomer can
be imparted with an antistatic property by adding thereto, a filler
capable of imparting electroconductivity thereto. By imparting an
antistatic property, it is made possible to prevent dust or dirt
from sticking to the gasket and cover body in the production step
of the gasketed cover. Examples of fillers capable of imparting
electroconductivity include powders and fibers of a metal such as
iron, stainless steel and aluminum, electroconductive fillers such
as carbon black and carbon fiber, polyalkylamine,
polyalkylsulfonate, quaternary ammonium chloride and
alkylbetaine.
[0039] The amount of the above-mentioned fillers to be added to the
thermoplastic resins or thermoplastic elastomers is preferably such
an amount that the resins or elastomers are made to have each a
volume resistivity of at most 1.times.10.sup.8 .OMEGA.cm. In the
case that the cover body is required to have properties of
shielding electromagnetic wave, said volume resistivity is
preferably at most 1.times.10.sup.2 .OMEGA.cm. In addition, the
thermoplastic elastomers, when incorporated with any one of the
fillers, have each JIS hardness A of preferably at most 80 degrees,
particularly preferably in the range of 10 to 50 degrees.
[0040] It is possible in the present invention to add a reinforcing
material to the foregoing thermoplastic resins or thermoplastic
elastomers to the extent that the effects of the present invention
are not impaired. Said reinforcing material is exemplified by
inorganic fiber such as glass fiber and carbon fiber, inorganic
filler such as mica and talc, and whiskers of potassium titanate
and the like.
[0041] The integration of the cover body and the gasket is made,
for instance, by the junction between the thermoplastic resin
constituting the cover body and the thermoplastic elastomer
constituting the gasket, specifically by means of two-color molding
method, inserting molding method or the like.
[0042] By means of the two-color molding method, there is formed
the composite gasketed cover in which the thermoplastic resin is
integrated with the thermoplastic elastomer layer formed thereon
through the steps of firstly subjecting the thermoplastic resin
constituting the cover body to melt injection molding into a die
with an injection molding machine for exclusive use, and after the
thermoplastic resin molding thus formed is solidified, subjecting
the thermoplastic elastomer which constitutes the gasket and is
excellent in fusion adhesivity to melt injection molding with an
injection molding machine for exclusive use so as to form the
thermoplastic elastomer layer on part of the thermoplastic resin
molding. The two-color molding method is capable of producing
composite gasketed covers in high production efficiency at a low
cost.
[0043] On the other hand, by means of the inserting molding method,
there is obtained the composite gasketed cover in which the
thermoplastic resin constituting the cover body is integrated with
the thermoplastic elastomer layer formed on part of the resin
through the steps of preparing in advance, the cover body having a
prescribed shape by any of various well known molding methods,
placing the resultant cover body in a die, and then forming the
thermoplastic elastomer layer on part of the cover body.
[0044] It is made possible in the first gasketed cover according to
the present invention to dispense with a rust preventive step and
reduce the weight of the same owing to the nonuse of a metallic
material; efficiently produce the same using a single mold in high
accuracy and precision at a low cost owing to the use of a
thermoplastic resin; recycle the material; produce highly
vibration-proof product owing to the use of a resin material
excellent in vibration-proofness; thereby prevent the generation of
vibration and noises; produce a gasket by means of injection
molding method owing to the use of the thermoplastic elastomer as
the gasket material; thus dispense with such procedure as punching
work of a material, adhesion work by using a double coated tape and
the like.
[0045] In summary, the first gasketed cover according to the
present invention can be efficiently produced in high accuracy and
in high precision at a low cost into an intricate configuration
with minimized waste material at the time of production without
necessitating a troublesome step. Besides, said cover is excellent
in lightweightness and sealing properties.
[0046] With regard to the second gasketed cover according to the
present invention, the material which constitutes the cover body is
not specifically limited, but can be properly selected for use
according to the purpose of use thereof from cold rolled steel
sheets, galvanized steel sheets, aluminum/zinc alloy plated steel
sheets, stainless steel sheets, aluminum sheets, aluminum alloy
sheets, magnesium sheets, magnesium alloy sheets, and the like.
There are also usable injection molded magnesium sheets. From the
viewpoint of corrosion resistance, there are preferably usable
metallic sheets treated with non-electrolytic nickel plating, As
the non-electrolytic nickel plating, there can be used a
conventional method which has heretofore been applied to metallic
raw material such as a method which comprises immersing a metallic
sheet to be treated in a non-electrolytic nickel plating bath
consisting of an aqueous solution at a pH of 4.0 to 5.0 approx. at
a temperature of 85 to 95.degree. C. approx. which contains, for
instance, nickel sulfate, sodium hypochlolite, lactic acid,
propionic acid and the like each at a proper proportion.
[0047] The thickness of the metallic sheet to be used in the second
gasketed cover according to the present invention, is properly
selected according to the purpose of use of the cover body, and is
in the range of usually 0.3 to 1.0 mm, preferably 0.4 to 0.6
mm.
[0048] The thermoplastic resin, when used for forming the cover
body in the second gasketed cover according to the present
invention, is exemplified by those which have been enumerated in
the description of the first gasketed cover.
[0049] The elastic body which constitutes the gasket and the member
in the second gasketed cover according to the present invention may
be selected for use from vulcanized rubber such as butyl rubber and
EPDM, and thermoplastic elastomers. The thermoplastic elastomers,
when used for forming the the gasket and the member in the second
gasketed cover, is exemplified by those which have been enumerated
in the description of the first gasketed cover.
[0050] The elastic body which constitutes the gasket and the member
is preferably a thermoplastic elastomer from the aspect of
dispensing with time for vulcanization or the like in production.
In addition, the combination of the material constituting the cover
body and the elastic body constituting the gasket and the member is
preferably the combination of a thermoplastic resin as the material
for the cover body and a thermoplastic elastomer as the material
for the gasket and the member from the point of view that even an
article having a complicated shape can be efficiently produced in
high accuracy and precision at a low cost. The combination of
thermoplastic resin as the material for the cover body and
thermoplastic elastomer as the material for the gasket and the
member is not specifically limited, but is exemplified by the
combination of an olefinic resin and a styrenic or olefinic
elastomer, the combination of nylon or ABS resin and urethane based
elastomer and the like. The member constituted of the elastic body
of a type same as or different from that for the gasket exhibits a
marked effect on suppressing the generation of noises, when located
in the vicinity of the middle of the cover body.
[0051] It is possible in the present invention to add a reinforcing
material to the foregoing thermoplastic resins or thermoplastic
elastomers to the extent that the effects of the present invention
are not impaired thereby. Said reinforcing material is exemplified
by inorganic fibers such as glass fiber and carbon fiber, inorganic
fillers such as mica and talc, and whiskers of potassium titanate
and the like.
[0052] The integration of the cover body, the gasket and the member
constituted of the material same as that for the gasket is made by
the following methods. In the case of the elastomer being a
thermoplastic elastomer, the gasket and the member constituted of
the elastic body of a type same as or different from that for the
gasket are injection molded to shape onto the cover body. In the
case where the cover body is made of the thermoplastic resin, and
the elastic body constituting the gasket and the member is the
thermoplastic elastomer, the integration is made by the junction
between said thermoplastic resin and thermoplastic elastomer,
specifically by two-color molding method, inserting molding method
or the like.
[0053] By means of the two-color molding method, there is formed
the composite gasketed cover in which the thermoplastic resin is
integrated with the thermoplastic elastomer layer formed thereon
through the steps of firstly subjecting the thermoplastic resin
constituting the cover body to melt injection molding into a die
with an injection molding machine for exclusive use, and after the
thermoplastic resin molding thus formed is solidified, subjecting
the thermoplastic elastomer which constitutes the gasket and is
excellent in fusion adhesivity to melt injection molding with an
injection molding machine for exclusive use so as to form
thermoplastic elastomer layer on part of the thermoplastic resin
molding.
[0054] On the other hand, by means of the inserting molding method,
there is obtained the composite gasketed cover in which the
thermoplastic resin constituting the cover body is integrated with
the thermoplastic elastomer layer formed on part of the resin
through the steps of preparing in advance, the cover body having a
prescribed shape by any of various well known molding methods,
placing the resultant cover body in a die, and then forming the
thermoplastic elastomer layer on part of the cover body.
[0055] The second gasketed cover according to the present invention
is capable of preventing the noises from being generated by the
vibration of the cover body, and is excellent in sealing
properties.
[0056] In regard to the electronic equipment cover according to the
present invention, the material constituting the cover body is not
specifically limited. There are usable a metallic sheet and a
thermoplastic resin, which are exemplified by those which have been
enumerated in the description of the second gasketed cover
according to the present invention.
[0057] The thickness of the metallic sheet to be used in the
electronic equipment cover according to the present invention, is
properly selected according to the purpose of use of the cover
body, and is in the range of usually 0.3 to 1.0 mm, preferably 0.4
to 0.6 mm.
[0058] The elastic body constituting the membrane has a
JIS-hardness A of preferably at most 70 degrees, particularly
preferably at most 50 degrees judging from the capability of
promptly expanding to the inside and also the outside of electronic
equipment in response to the pressure variation in the inside and
outside thereof. There are usable as the elastic body, vulcanized
rubber such as butyl rubber and EPDM, and thermoplastic elastomer.
The thermoplastic elastomer is exemplified by those which have been
enumerated in the description of the first gasketed cover.
[0059] The thickness of the membrane, which depends upon the
elastic body constituting the same, ranges usually from 0.2 to 1.0
mm. Moreover, the electronic equipment cover according to the
present invention may be equipped at need, with a gasket made of
the elastic body of a type same as or different from that for the
membrane.
[0060] The elastic body which constitutes the gasket and the
membrane is preferably a thermoplastic elastomer from the aspect of
dispensing with vulcanization time, etc. in production. Moreover,
the combination of the material constituting the cover body and the
material constituting the gasket and the membrane is preferably the
combination of a thermoplastic resin as the material for the cover
body and a thermoplastic elastomer as the material for the gasket
and the membrane from the point of view that even an article having
a complicated shape can be efficiently produced in high accuracy
and precision at a low cost. The combination of thermoplastic resin
as the material for the cover body and thermoplastic elastomer as
the material for the gasket and membrane is not particularly
limited, but is exemplified by the combination of an olefinic resin
and a styrenic or olefinic elastomer, the combination of nylon or
ABS resin and urethane based elastomer and the like.
[0061] The thermoplastic resin or the thermoplastic elastomer can
be imparted with an antistatic property by adding thereto, a filler
capable of imparting electroconductivity thereto. By imparting an
antistatic property, it is made possible to prevent dust or dirt
from sticking to the gasket and cover body in the production step
of the gasketed cover. Examples of fillers capable of imparting
electroconductivity include powders and fibers of a metal such as
iron, stainless steel and aluminum, electroconductive fillers such
as carbon black and carbon fiber, polyalkylamine,
polyalkylsulfonate, quaternary ammonium chloride and
alkylbetaine.
[0062] The amount of the fillers added to the thermoplastic resins
or thermoplastic elastomers is preferably such an amount that the
resins or elastomers have each a volume resistivity of at most
1.times.10.sup.8 .OMEGA.cm. In the case of the cover body being
required to have properties of shielding electromagnetic wave, said
volume resistivity is preferably at most 1.times.10.sup.2
.OMEGA.cm. In addition, the thermoplastic elastomers, when
incorporated with any one of the fillers, have each a JIS hardness
A of preferably at most 80 degrees, particularly preferably in the
range of 10 to 50 degrees.
[0063] It is possible in the present invention to add a reinforcing
material to the foregoing thermoplastic resins or thermoplastic
elastomers to the extent that the effects of the present invention
are not impaired thereby. said reinforcing material is exemplified
by inorganic fibers such as glass fiber and carbon fiber, inorganic
fillers such as mica and talc, and whiskers of potassium titanate
and the like.
[0064] In an attempt to prepare the electronic equipment cover
according to the present invention, at first a cover body having a
through hole on a plane portion is prepared by means of injection
molding method or the like. The integration of the cover body, the
gasket which is provided at need and the membrane consisting of the
elastic body of a type same as or different from that of the
gasket, is made by any of the following methods. In the case where
the elastic body which constitutes the membrane and the gasket is a
thermoplastic elastomer, the integration is made by injection
molding method so as to shape the gasket and the membrane onto the
cover body. In this case, the membrane is integrated with the cover
body by interposing the peripheral portion of the cover body hole
with the elastic body at the outer periphery of membrane. In the
case where the material for the cover body is a thermoplastic
resin, and the materials for the gasket and membrane are each a
thermoplastic elastomer, the integration is made by the junction
between said thermoplastic resin and said thermoplastic elastomer,
specifically by means of twocolor molding method, inserting molding
method or the like.
[0065] By means of the two-color molding method, there is formed
the electronic equipment cover in which the thermoplastic resin is
integrated with the thermoplastic elastomer layer formed thereon
through the steps of firstly subjecting the thermoplastic resin
constituting the cover body to melt injection molding into a die
with an injection molding machine for exclusive use, and after the
thermoplastic resin molding thus formed is solidified, subjecting
the thermoplastic elastomer which constitutes the gasket and is
excellent in fusion adhesivity to melt injection molding with an
injection molding machine for exclusive use so that the
thermoplastic elastomer layer is formed on part of the
thermoplastic resin molding.
[0066] On the other hand, by means of the inserting molding method,
there is formed the electronic equipment cover in which the
thermoplastic resin constituting the cover body is integrated with
the thermoplastic elastomer layer formed thereon through the steps
of preparing in advance, the cover body having a prescribed shape
by any of various well known molding methods, placing the resultant
cover body in a die, and then forming the thermoplastic elastomer
layer on part of the cover body.
[0067] The electronic equipment cover according to the present
invention is capable of preventing a pressure difference from being
generated between the inside and the outside of the main body of
the electronic equipment.
[0068] In the following, the present invention will be described in
further detail with reference to working examples, which however
shall not limit the present invention thereto.
EXAMPLE 1
[0069] FIG. 1 is a cross sectional view showing the gasketed cover
according to the present invention wherein the underside thereof
indicates the sealing surface side. FIG. 2 is a perspective
illustration viewed from the sealing surface side for the gasketed
cover shown in FIG. 1. In both FIG. 1 and FIG. 2, the symbols mean
the following: 1; cover body, 2; gasket, 3; flange, 4; rib, and the
gasket 2 is fusedly bonded to the flange 3.
[0070] The gasketed cover was prepared by two-color molding method
in accordance with the following procedures. Firstly, the
thermoplastic resin constituting the cover body 1 was prepared by
kneading 100 parts by weight of 33% short glass fiber-reinforced
nylon (produced by Asahi Chemical Industry Co.,Ltd. under the trade
name "Reona 1300G") and 4 parts by weight of carbon black (produced
by Mitsubishi Chemical Industry Co.,Ltd. under the trade name
"Ketchen Black EC "). The resultant thermoplastic resin for the
cover body had a volume resistivity of 1.times.10.sup.5 .OMEGA.cm.
The thermoplastic elastomer constituting the gasket 2 was prepared
by kneading 100 parts by weight of the urethane based elastomer
(produced by Nippon Miractran Co.,Ltd. under the trade name
"Miractran E 660") and 4 parts by weight of carbon black (produced
by Mitsubishi Chemical Industry Co.,Ltd. under the trade name
"Ketchen Black EC"). The resultant thermoplastic elastomer for the
gasket had a volume resistivity of 1.times.10.sup.6 .OMEGA.cm and a
JIS hardness A of 70 degrees.
[0071] Thereafter, by the use of a molding machine (produced by
Nissei Plastic Industrial Co.,Ltd. under the trade name "DC40E
5ASE") the above-prepared thermoplastic resin for the cover body
was subjected to melt injection molding into a die at a die
temperature of 50.degree. C. and a resin temperature of 280.degree.
C., and subsequently the above-prepared thermoplastic elastomer was
subjected to melt injection molding onto the resultant molding in
the die at a die temperature of 50.degree. C. and resin temperature
of 200.degree.C. After all, there was prepared a gasketed cover in
which the cover body and gasket were integratedly composited with
each other. The gasketed cover thus prepared was used as the cover
in a hard disc apparatus of a computer. As a result, sufficient
sealing properties in the gasketed cover was maintained for a long
period of time.
EXAMPLE 2
[0072] FIG. 3 is a cross sectional view showing the gasketed cover
according to the present invention wherein the cover body and the
gasket are non-fusedly bonded to each other. In FIG. 3, the symbols
mean the following: 5; cover body, 6; anchor portion, 7; gasket, 8;
rib.
[0073] The gasketed cover was prepared by injection molding method
in accordance with the following procedures. Firstly, the
thermoplastic resin constituting the cover body 5 was prepared by
kneading 100 parts by weight of 30% glass fiber reinforced ABS
resin (produced by Asahi Chemical Industry Co.,Ltd. under the trade
name "Styrack R 260A") and 4 parts by weight of carbon black
(produced by Mitsubishi Chemical Industry Co.,Ltd. under the trade
name "Ketchen Black EC") The resultant thermoplastic resin for the
cover body had a volume resistivity of 1.times.10.sup.5 .OMEGA.cm.
The thermoplastic elastomer constituting the gasket 7 was prepared
by kneading 100 parts by weight of the styrenic elastomer (produced
by Mitsubishi Chemical Industry Co.,Ltd. under the trade name
"Rubberon MJ 4300B ") and 4 parts by weight of carbon black
(produced by Mitsubishi Chemical Industry Co.,Ltd. under the trade
name "Ketchen Black EC") The resultant thermoplastic elastomer for
the gasket had a volume resistivity of 1.times.10.sup.6 .OMEGA.cm
and a JIS hardness A of 45 degrees.
[0074] Thereafter, by the use of a molding machine (produced by
Nissei Plastic Industrial Co.,Ltd. under the trade name "FE120 S25
ASE") the above-prepared thermoplastic resin for the cover body was
subjected to melt injection molding into a die at a die temperature
of 50.degree. C. and a resin temperature of 230.degree. C., the
resultant cover body was taken out from the die and was inserted in
a die which had been fitted to an injection molding
machine(produced by Nissei Plastic Industrial Co., Ltd. under the
trade name "TH30 R5 VSE"), and subsequently the above-prepared
thermoplastic elastomer for the gasket was subjected to injection
molding onto the resultant molding at a die temperature of
50.degree. C. and a resin temperature of 200.degree. C. After all,
there was prepared a gasketed cover in which the cover body and
gasket were integratedly composited with each other. The gasketed
cover thus prepared was used as the cover in a hard disc apparatus
of a computer in the same manner as in Example 1. As a result,
sufficient sealing properties in the gasketed cover was maintained
for a long period of time.
EXAMPLE 3
[0075] The gasketed cover as illustrated in FIG. 3 was prepared by
injection molding method in accordance with the following
procedures. As the synthetic resin constituting the cover body 5,
there was used 30% carbon fiber-reinforced polyphenylene sulfide
(PPS) resin (produced by Tosoh Corporation under the trade name
"SUSTEEL CH-30-12"). The resultant synthetic resin for the cover
body had a volume resistivity of 6.times.10.sup.5 .OMEGA.cm. The
synthetic resin-based elastomer constituting the gasket 7 was
prepared by kneading 100 parts by weight of the styrenic elastomer
(produced by Mitsubishi Chemical Industry Co.,Ltd. under the trade
name "Rubberon MJ 4300B") and 4 parts by weight of carbon black
(produced by Mitsubishi Chemical Industry Co.,Ltd. under the trade
name "Ketchen Black EC"). The resultant synthetic resin-based
elastomer for the gasket had a volume resistivity of
1.times.10.sup.6 .OMEGA.cm and a JIS hardness A of 45 degrees.
[0076] Thereafter, by the use of a molding machine (produced by
Nissei Plastic Industrial Co.,Ltd. under the trade name "FE120 S25
ASE") the above-prepared thermoplastic resin for the cover body was
subjected to melt injection molding into a die at a die temperature
of 140.degree. C. and a resin temperature of 320.degree. C., the
resultant cover body was taken out from the die and was inserted in
a die which had been fitted to an injection molding
machine(produced by Nissei Plastic Industrial Co., Ltd. under the
trade name "TH30 R5 VSE"), and subsequently the above-prepared
thermoplastic elastomer for the gasket was subjected to injection
molding onto the resultant molding at a die temperature of
50.degree. C. and a resin temperature of 200.degree. C. After all,
there was prepared a gasketed cover in which the cover body and
gasket were integratedly composited with each other. The gasketed
cover thus prepared was used as the cover in a hard disc apparatus
of a computer in the same manner as in Example 1. As a result,
sufficient sealing properties in the gasketed cover was maintained
for a long period of time.
EXAMPLE 4
[0077] FIG. 4 is a perspective illustration viewed from the sealing
surface side for the gasketed cover according to the present
invention. In FIG. 4, the symbols mean the following: 21; cover
body, 22; gasket, 23; flange, 24; rib, 25; member consisting of the
elastic body same as that for the gasket. The gasket 22 is fusedly
bonded to the flange 23, and the member 25 is fusedly bonded to
each of middle parts of the plane portion of the cover body 21 that
is divided with ribs 24. The gasketed cover has a size of 100
mm.times.70 mm, and the member 25 has a diameter of 10 mm and a
height of 1 mm.
[0078] The gasketed cover was prepared by two-color molding method
in accordance with the following procedures. There were used 33%
short glass fiber-reinforced nylon (produced by Asahi Chemical
Industry Co.,Ltd. under the trade name "Reona 1300G") as the
thermoplastic resin constituting the cover body 21, and the
urethane based elastomer (produced by Nippon Miractran Co.,Ltd.
under the trade name "Miractran E 660") as the thermoplastic
elastomer constituting the gasket 22 and the member 25. The
thermoplastic elastomer had a JIS hardness A of 70 degrees.
[0079] Thereafter, by the use of a molding machine (produced by
Nissei Plastic Industrial Co.,Ltd. under the trade name "DC 60E
5ASE") the above-prepared thermoplastic resin for the cover body
was subjected to melt injection molding into a die at a die
temperature of 50.degree. C. and a resin temperature of 280.degree.
C., and subsequently the above-prepared thermoplastic elastomer was
subjected to melt injection molding onto the resultant molding in
the die at a die temperature of 50.degree. C. and a resin
temperature of 200.degree. C. After all, there was prepared a
gasketed cover in which the cover body and gasket were integratedly
composited with each other. The gasketed cover thus prepared was
used as the cover in a hard disc apparatus of a computer. As a
result, it was recognized that noise generation was remarkably
decreased as compared with the gasketed cover which was not
equipped on the plane portion of the cover body 21 with the member
consisting of the elastic body same as that of the gasket.
EXAMPLE 5
[0080] FIG. 5 is a perspective illustration viewed from the sealing
surface side for the electronic equipment cover according to the
present invention. In FIG. 5, the gasket and the membrane portion
are fusedly bonded to the cover body. FIG. 6 is a cross sectional
view taken on the line A-A' of FIG. 5. In FIG. 5 and FIG. 6 (A),
the symbols mean the following: 31; cover body, 32; gasket, 33;
flange, 34; rib, 35; membrane portion which consists of the elastic
body same as that for the gasket and is located on the plane of the
cover body 31. The gasketed cover has a size of 100 mm.times.70 mm,
and the holes made in the cover body 31 has a diameter of 10 mm,
and the membrane has a thickness of 0.4 mm.
[0081] The electronic equipment cover was prepared according to the
following procedures. The thermoplastic resin constituting the
cover body 1 was prepared by kneading 100 parts by weight of 33%
short glass fiber-reinforced nylon (produced by Asahi Chemical
Industry Co.,Ltd. under the trade name "Reona 1300G") and 4 parts
by weight of carbon black (produced by Mitsubishi Chemical Industry
Co.,Ltd. under the trade name "Ketchen Black EC") The thermoplastic
elastomer constituting the gasket 32 and the membrane 35 was
prepared by kneading 100 parts by weight of SEPS having a
number-average molecular weight of 100,000 and a styrene moiety of
30% by weight; 150 parts by weight of paraffin base oil having a
kinematic viscosity at 40.degree. C. of 380 cSt (produced by
Idemitsu Kosan Co.,Ltd. under the trade name "Diana Process Oil
PW380"); and 12.5 parts by weight of polypropylene (produced by
Mitsubishi Chemical Industry Co.,Ltd. under the trade name
"Mitsubishi polypropylene BC 05B"). The resultant thermoplastic
elastomer for the gasket 32 and the membrane 35 had a JIS hardness
A of 22 degrees.
[0082] Thereafter, by the use of a molding machine (produced by
Nissei Plastic Industrial Co.,Ltd. under the trade name "FE120 S25
ASE") the above-prepared thermoplastic resin for the cover body was
subjected to melt injection molding into a die at a die temperature
of 50.degree. C. and a resin temperature of 230.degree. C., the
resultant cover body was taken out from the die and was inserted in
a die which had been fitted to an injection molding
machine(produced by Nissei Plastic Industrial Co., Ltd. under the
trade name "TH30 R5 VSE"), and then the resultant thermoplastic
elastomer was subjected to injection molding onto the resultant
molding at a die temperature of 50.degree. C. and a resin
temperature of 200.degree. C. After all, there was prepared a
gasketed cover in which the cover body and gasket were integratedly
composited with each other. The electronic equipment cover
according to the present invention can take the configuration of
any of FIG. 6(B), FIG. 6(C) and FIG. 6(D). The gasketed cover was
used as the cover in a hard disc apparatus of a computer. As a
result, over a long period of time the aforesaid gasketed cover was
free from any malfunctioning considered to have arisen from the
variation in the internal pressure of the main body of the hard
disc apparatus.
* * * * *