GB2326201A - Gaskets - Google Patents
Gaskets Download PDFInfo
- Publication number
- GB2326201A GB2326201A GB9712117A GB9712117A GB2326201A GB 2326201 A GB2326201 A GB 2326201A GB 9712117 A GB9712117 A GB 9712117A GB 9712117 A GB9712117 A GB 9712117A GB 2326201 A GB2326201 A GB 2326201A
- Authority
- GB
- United Kingdom
- Prior art keywords
- sealing layer
- gasket
- vermiculite
- gasket according
- density
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/02—Sealings between relatively-stationary surfaces
- F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
- F16J15/10—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K3/00—Materials not provided for elsewhere
- C09K3/10—Materials in mouldable or extrudable form for sealing or packing joints or covers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16J—PISTONS; CYLINDERS; SEALINGS
- F16J15/00—Sealings
- F16J15/02—Sealings between relatively-stationary surfaces
- F16J15/06—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces
- F16J15/10—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing
- F16J15/12—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering
- F16J15/121—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering with metal reinforcement
- F16J15/122—Sealings between relatively-stationary surfaces with solid packing compressed between sealing surfaces with non-metallic packing with metal reinforcement or covering with metal reinforcement generally parallel to the surfaces
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
- C09K2200/00—Chemical nature of materials in mouldable or extrudable form for sealing or packing joints or covers
- C09K2200/02—Inorganic compounds
Landscapes
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Sealing Material Composition (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
A gasket comprises a sealing layer formed from a resilient material which comprises particles of chemically-exfoliated vermiculite bonded together. The sealing layer has a density, in an uncompressed state, of less than 1.6 g/cm<SP>3</SP> preferably between 0.8 and 1.4 g/cm<SP>3</SP>. The sealing layer also has a hydrolysis-resistant polymer coupled to the vermiculite by a coupling agent, preferably silane. The polymer is selected from nitrile butadiene rubbers, styrene butadiene rubbers, natural rubber, butyl rubber and ethylene propyldiene monomer. The sealing layer can also have particles of gas-exfoliated vermiculite, talc, mica, or unexfoliated vermiculite. The sealing layer is bonded to a metal sheet of the gasket.
Description
GASKETS
This invention is concerned with gaskets, in particular with gaskets having a sealing layer which is formed from particles of chemically-exfoliated vermiculite.
Exfoliated vermiculite is a known heat-resistant resilient material. Exfoliated vermiculite is conventionally formed by expanding mineral vermiculite using gas, this material being referred to herein as "gasexfoliated vermiculite". The gas may be thermally generated, in which case the product is called "thermallyexfoliated vermiculite" (TEV). TEV may be made by flashheating mineral vermiculite to 750-10000c, at which temperature the water (free and combined) in the ore vaporises rapidly and the steam generated forces apart the silicate sheets which form the raw material, so bringing about an expansion of 10-20 times perpendicular to the plane of the sheets. The granules formed have a chemical composition which (apart from the loss of water) is virtually identical to that of the raw material. Gasexfoliated vermiculite may also be made by treating raw vermiculite with a liquid chemical, eg hydrogen peroxide, that penetrates between the silicate sheets and subsequently evolves a gas, eg oxygen, to bring about exfoliation. Chemically-exfoliated vermiculite (CEV) is a different form of exfoliated vermiculite and is formed by treating the ore and swelling it in water. In one possible preparation method, the ore is treated with saturated sodium chloride solution to exchange magnesium ions for sodium ions, and then with n-butyl ammonium chloride to replace sodium ions with n-C4H9NH3 ions. On washing with water swelling takes place. The swollen material is then subjected to high shear to produce an aqueous suspension of very fine (diameter below 50 microns) vermiculite particles.
It is known to utilise chemically-exfoliated vermiculite in a sealing layer of a sheet gasket, eg an automotive head gasket. For example, GB 2 123 034 B describes making a flexible sheet material, eg for a gasket, by subjecting an aqueous suspension to electrophoresis. The suspension contains an expanded layer silicate, eg CEv with a particle size below 50 microns, and a dispersed organic polymeric material, eg acrylic polymer, acrylonitrile-butadiene copolymer, epoxy resin, or natural rubber.
One of the desirable properties of a gasket is high stress retention and it has been assumed that the way to achieve high stress retention in a gasket with a sealing layer formed from CEV is to compress the layer consolidate it to approaching the theoretical density of CEV. Thus, such sealing layers have previously been formed with a density of 2.0 to 2.4 g/cm3. However, such gaskets, although they have low gas permeability, exhibit undesirably low stress retention.
It is an object of the present invention to provide a gasket comprising a sealing layer based on CEv which has improved stress retention, while retaining low gas permeability
The invention provides a gasket comprising a sealing layer formed from a resilient material which comprises particles of chemically-exfoliated vermiculite bonded together, wherein the sealing layer has a density, in an uncompressed state, of less than 1.6 g/cm3.
In a gasket according to the invention, in which the density of the sealing layer is much lower than is conventional, it is surprisingly found that stress retention is greatly increased while low gas permeability is also present.
In a gasket according to the invention, the sealing layer may have a density, in an uncompressed state, of less than 1.4 g/cm3, for example the density may be between 0.8 and 1.4 g/cm3.
In order to improve the water resistance of a sealing layer according to the invention, it is preferred that the sealing layer also comprises a hydrolysis-resistant polymer which may be coupled to the vermiculite by a coupling agent.
Said polymer may be selected from nitrile butadiene rubbers, styrene butadiene rubbers, natural rubber, butyl rubber, and ethylene propyldiene monomer. Diene-based polymers are suitable because they are flexible and hydrolysis-resistant. Also suitable are hydrolysisresistant types of silicone elastomer.
A suitable coupling agent is a silane, eg a vinyl functional silane such as triethoxy vinyl silane, (CH3CH2O) 3S iCH=CH2.
Since CEV is a relatively expensive material compared with gas-exfoliated vermiculite, eg TEV, in a gasket according to the invention, the sealing layer may also comprise particles of gas-exfoliated vermiculite, eg the layer may comprise particles of gas-exfoliated vermiculite bonded together by particles of CEV. The gas-exfoliated vermiculite may be milled to a particle size of less than 50 microns. Other possible additives include talc, mica and unexfoliated vermiculite (both natural and chemicallymodified). One additive may be intumescent to improve sealing at high temperatures.
Said sealing layer may be bonded, eg mechanically, to a sheet of the gasket. For example, mechanical bonding may be achieved by tangs projecting from the sheet into the layer. The sheet may be of stainless steel, carbon steel, or wire mesh.
There now follows a detailed description of an illustrative example according to the invention.
In the illustrative example, a tanged stainless steel sheet was first prepared. This sheet was 100 microns in thickness. The sheet was tanged by perforating it with square holes, each hole being 1.5 mm square and the hole centre-spacing being 3 mm. Half the holes were perforated by passing a tool through the sheet in a first direction and the remaining half, which alternated with the firstmentioned half, were perforated by passing a tool through the sheet in the opposite direction. The edges of the holes, thus, formed tangs projecting from the sheet in opposite directions. The tangs projected by about 1 mm.
In the illustrative example, 0.659 kg of an aqueous slurry (15% solids) was obtained containing about 99g of
CEV particles (the slurry was obtained from Grace
Construction Products Limited and is designated "Microlite HTS"). To this slurry was added 0.121 kg of particles of spray-dried CEv having particle size about 45 microns obtained from Grace Construction Products and designated "Microlite Powder". To this, was added 0.220 kg of Dupre
Superfine TEV. This gave a paste having approximately 44% solids. To this paste was added 4g of a coupling agent (a vinyl functional silane called "Silquest A-151" obtainable from OSi Specialities) and further mixing was carried out.
Next, a hydrolysis-resistant polymer/solvent mixture was prepared. This mixture was 50 g of solid nitrile butadiene rubber (Nippon Zeon N36C80), 250 g of toluene, and 3.1 g of a curing agent ("Dicup 40", dicumylperoxide) 132 g of this mixture was added to the above-mentioned paste and mixing was carried out. This gave a paste with approximately 5 % rubber content.
Next, the paste (including the polymer/solvent mixture) was spread over one side of the metal sheet mentioned above. The sheet was then passed between calendering rollers so that the thickness of the layer of paste was 2.lmm. The paste was then dried which reduced its thickness to 1.6mm. The same quantity of paste was then spread over the other side of the metal sheet and the calendering and drying was repeated. The layers of vermiculite were then pressed to consolidate the material to a density of 0.89 g/cm3 which formed sealing layers approximately 1 mm thick on both sides of the metal sheet.
Then, it was heated to peroxide cure the rubber. A gasket was then cut out from the sheet. The gasket was in the form of a ring, having an internal diameter of 55mm and an external diameter of 75mm.
The completed gasket obtained by the illustrative example had two sealing layers formed from a resilient material. The resilient material comprised particles of CEv bonded together, and coupled to the nitrile butadiene rubber by the silane.
The gasket obtained by the illustrative example was tested to determine its stress retention. The gasket was placed in a test rig as described in the appendix to
British Standard 7531 and stressed to 40 MPa. The gasket was heated to 3000c over a period of 1 hour and then held at that temperature for 16 hours. The stress retention was then measured and found to be 30 MPa. The gasket obtained by the illustrative example was also found to have low gas permeability properties (leakage of only 0.02 ml/minute in the test described in DIN 3754).
As a comparative example, the illustrative example was repeated except that the paste was spread on to the metal sheet to a thickness of 3.3 mm which dried to a thickness of 2.4 mm. The layers were pressed to a thickness of 1 mm giving them a density of 1.66 g/cm3. The gasket obtained by the comparative example was tested by the method described above to determine its stress retention, the result being 16.4 MPa. The gasket obtained by the comparative example was also found to have acceptable gas permeability properties (leakage of 0.12 ml/minute in the DIN test).
Claims (10)
1 A gasket comprising a sealing layer formed from a
resilient material which comprises particles of
chemically-exfoliated vermiculite bonded together,
wherein the sealing layer has a density, in an
uncompressed state, of less than 1.6 g/cm3.
2 A gasket according to claim 1, wherein the sealing
layer has a density, in an uncompressed state, of less
than 1.4 g/cm3.
3 A gasket according to either one of claims 1 and 2,
wherein the sealing layer has a density, in an
uncompressed state, of between 0.8 and 1.4 g/cm3.
4 A gasket according to any one of claims 1 to 3,
wherein the sealing layer also comprises a hydrolysis
resistant polymer coupled to the vermiculite by a
coupling agent.
5 A gasket according to claim 4, wherein said polymer is
selected from nitrile butadiene rubbers, styrene
butadiene rubbers, natural rubber, butyl rubber, and
ethylene propyldiene monomer.
6 A gasket according to either one of claims 4 and 5,
wherein the coupling agent is a silane.
7 A gasket according to any one of claims 1 to 6,
wherein said sealing layer is bonded to a metal sheet
of the gasket.
8 A gasket according to any one of claims 1 to 7,
wherein the sealing layer also comprises particles of
gas-exfoliated vermiculite.
9 A gasket according to any one of claims 1 to 8,
wherein the sealing layer also comprises particles of
talc, mica or unexfoliated vermiculite.
10 A gasket substantially as hereinbefore described with
reference to the illustrative example.
Priority Applications (12)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9712117A GB2326201B (en) | 1997-06-12 | 1997-06-12 | Gaskets |
EP01104077.1A EP1132447B1 (en) | 1997-05-21 | 1998-05-06 | Gaskets |
EP00107663A EP1033394B1 (en) | 1997-05-21 | 1998-05-06 | Gaskets |
US09/424,123 US6610771B1 (en) | 1997-05-21 | 1998-05-06 | Gaskets |
KR1020037005121A KR100559928B1 (en) | 1997-05-21 | 1998-05-06 | Gaskets |
JP55007998A JP2002502448A (en) | 1997-05-21 | 1998-05-06 | gasket |
PCT/GB1998/001309 WO1998053022A1 (en) | 1997-05-21 | 1998-05-06 | Gaskets |
KR1019997010710A KR100559929B1 (en) | 1997-05-21 | 1998-05-06 | Gaskets |
EP98920637A EP0996695A1 (en) | 1997-05-21 | 1998-05-06 | Gaskets |
BRPI9816175A BRPI9816175B8 (en) | 1997-05-21 | 1998-05-06 | gasket. |
AU73430/98A AU7343098A (en) | 1997-05-21 | 1998-05-06 | Gaskets |
BRPI9809128-0A BR9809128A (en) | 1997-05-21 | 1998-05-06 | Gasket |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9712117A GB2326201B (en) | 1997-06-12 | 1997-06-12 | Gaskets |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9712117D0 GB9712117D0 (en) | 1997-08-13 |
GB2326201A true GB2326201A (en) | 1998-12-16 |
GB2326201B GB2326201B (en) | 2001-04-04 |
Family
ID=10813958
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9712117A Expired - Fee Related GB2326201B (en) | 1997-05-21 | 1997-06-12 | Gaskets |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2326201B (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016185220A1 (en) * | 2015-05-20 | 2016-11-24 | Flexitallic Limited | Sealing material |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0379636A1 (en) * | 1988-09-08 | 1990-08-01 | T&N TECHNOLOGY LIMITED | Improvements in and relating to gasket materials |
US4961988A (en) * | 1987-09-28 | 1990-10-09 | Zhejiang Ci Xi Seal Material Factory | General packing of expanded graphite |
-
1997
- 1997-06-12 GB GB9712117A patent/GB2326201B/en not_active Expired - Fee Related
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4961988A (en) * | 1987-09-28 | 1990-10-09 | Zhejiang Ci Xi Seal Material Factory | General packing of expanded graphite |
US4961988B1 (en) * | 1987-09-28 | 1993-12-14 | Zhejiang Ci Xi Seal Material Factory | General packing of expanded graphite |
EP0379636A1 (en) * | 1988-09-08 | 1990-08-01 | T&N TECHNOLOGY LIMITED | Improvements in and relating to gasket materials |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016185220A1 (en) * | 2015-05-20 | 2016-11-24 | Flexitallic Limited | Sealing material |
US11345633B2 (en) | 2015-05-20 | 2022-05-31 | Flexitallic Investments, Inc. | Sealing material |
Also Published As
Publication number | Publication date |
---|---|
GB2326201B (en) | 2001-04-04 |
GB9712117D0 (en) | 1997-08-13 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
730 | Substitution of applicants allowed (sect. 30/1977) | ||
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20040612 |