AU713243B2 - Gasket paper - Google Patents
Gasket paper Download PDFInfo
- Publication number
- AU713243B2 AU713243B2 AU30990/97A AU3099097A AU713243B2 AU 713243 B2 AU713243 B2 AU 713243B2 AU 30990/97 A AU30990/97 A AU 30990/97A AU 3099097 A AU3099097 A AU 3099097A AU 713243 B2 AU713243 B2 AU 713243B2
- Authority
- AU
- Australia
- Prior art keywords
- mixture
- added
- weight
- paper
- polymeric binder
- 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.)
- Ceased
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H13/00—Pulp or paper, comprising synthetic cellulose or non-cellulose fibres or web-forming material
- D21H13/10—Organic non-cellulose fibres
- D21H13/20—Organic non-cellulose fibres from macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
- D21H13/26—Polyamides; Polyimides
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
- D21H17/63—Inorganic compounds
- D21H17/67—Water-insoluble compounds, e.g. fillers, pigments
- D21H17/68—Water-insoluble compounds, e.g. fillers, pigments siliceous, e.g. clays
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Dispersion Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Sealing Material Composition (AREA)
- Paper (AREA)
- Materials For Medical Uses (AREA)
Description
I I;
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WO 97/49864 PCTGB97/01587 -1- Gasket Paper This invention relates to papers particularly, but not exclusively, suitable for use in fluid sealing applications such as cylinder head gaskets. It is known to make gasket papers from non-asbestos formulations based on other fibres such as glass fibres and/or mineral fibres and including a minor proportion of cellulose as a web-forming agent. For example, GB-A-2138854 and 2138855 disclose cellulose-containing compositions using ball clay as a filler. GB-A-2250302 discloses a gasket material which is cellulose-free and which includes a carefully selected mixture of calcined china clay and ball clay as filler.
Whilst these non-asbestos products containing ball clay have good performance in noncritical applications, it has been observed that their behaviour at elevated temperatures is not adequate as regards stress relaxation (or creep), particularly when tested over an extended period of time to simulate actual use. Stress relaxation or creep results in a loss of loading in a bolted joint and can lead to gasket failure, so that in temperature critical applications, better stress retention is very desirable.
It has now been discovered that replacement of the ball clay component by a layered kaolinitic clay or a fibrous chain silicate, or by a mixture of these results in improved stress relaxation performance.
According to the present invention, a method of manufacture of a paper stock for dewatering to paper, comprising by weight 4-15% aramid fibre pulp, 60-90% silicate mineral, 4-10% polymeric binder and 2-15% inorganic binder, comprises the steps of SUBSTITUTE SHEET (RULE 26) WO 97/49864 PCTIGB97/01587 -2mixing the aramid fibres in water to produce a slurry of about 2% solids content by weight, diluting the pulp with water, adding the silicate mineral to the mixture, agitating the mixture, further diluting the mixture with water to produce a slurry of about 4% solids content by weight, adding a 10% solution of papermakers alum such that the dry content is about 1% of the total composition, agitating the mixture, adding to the mixture the inorganic binder, adding to the mixture the polymeric binder having a solids content of about 50% by weight, waiting until the polymeric binder is fully dispersed and adding a further quantity of the papermakers alum solution until the supematant liquid becomes clear.
According to a further aspect of the invention, at least some of the silicate mineral is constituted by attapulgite.
The inorganic binder is preferably colloidal silica. The polymeric material is preferably nitrile rubber.
A particularly preferred paper produced according to the inventive method comprises by weight, 4-8% aramid fibre pulp, 5-8% polymeric binder, 75-90% silicate mineral and 4-10% colloidal silica. It will be appreciated that in the present context "aramid" is a reference to polyaromatic amide material.
The formulations of the present invention may be used in at least two different ways.
Firstly, the use of calcined china clay in combination with colloidal silica lends itself to the product of a paper which can be impregnated with a silicone or other resin such as polybutadiene in order to enhance resistance to and sealabilty against fluids such as water-antifreeze mixtures and oil. Alternatively, by including attapulgite it is possible to produce a paper which swells when exposed to water. Such papers can be used without a resin impregnation treatment.
The invention therefore includes a process for producing gaskets from the paper of this invention, both with and without a post-treatment with a resin impregnant.
Surprisingly, it has been found that by eliminating ball clay (previously regarded as a critical ingredient) in favour of the formulations of the present invention, it is possible to SUBSTITUTE SHEET (RULE 26) WO 97/49864 PCTIGB97101587 -3achieve improved stress relaxation performance at elevated temperatures, without using inorganic fibres.
In order that the invention be better understood, preferred embodiments of it will now be described by way of example with reference to the following Examples.
In the interests of clarity, the stress relaxation performance was determined by a method based on ASTM test F1276, the samples being exposed to 300 0 C for 22 hours. It will be appreciated that the latter is significantly longer than some other tests, but investigation reveals that stress relaxation is appreciably higher after longer exposures, which more closely approximate actual use.
Thus testing was carried out by bonding the test paper to both sides of a plain steel core, blanking out annular samples of inside diameter 14.7mm and outside diameter 34.5mm.
These were then tested, again based on ASTM F1276, by applying an initial stress of 58.6 MPa. After 22 hours at 300 0 C the residual stress was measured, the stress relaxation calculated and then normalised to a paper thickness of 1.0mm, in the usual way. This procedure was used throughout the following Examples, including tests on paper made according to prior art.
Examole 1 A paper was made having the following composition: by dry weight Fibrillated Aramid Fibre Pulp 8 Calcined China Clay 76 Nitrile Rubber 6 Colloidal Silica Stock Preparation The aramid fibres were dispersed in water to give a slurry of around 2% solids content by weight. This pulp had a freeness of 50 0 SR. The pulp was transferred to a mixing vessel and further diluted with water at 40 0 C. The calcined china clay was added and the mixture SUBSTITUTE SHEET (RULE 26) WO 97/49864 PCT/GB97/01587 -4agitated. Further water was added to give a slurry having a solids content of approximately 4% by weight. A 10% solution of papermakers alum was added such that the dry content was approximately 1% of the total composition. The mixture was agitated for 2 minutes before adding the colloidal silica as a 30% solids content suspension. The mixture was agitated for a further 5 minutes and nitrile rubber added in latex form, having a solids content of around 50%. The nitrile rubber latex was diluted 5:1 with water before adding to the mix. When fully dispersed the latex was then caused to precipitate onto the fibres and fillers by the addition of a further quantity of papermakers alum solution until the supernatant liquid became clear.
Paper Manufacture A paper was produced from the above stock by the conventional technique of dewatering on a wire mesh, pressing and drying, a polyacrylamide flocculant was used to aid processing. The paper was subsequently calendered to the required density using a conventional 2-bowl calender.
The resulting paper had the following properties: Thickness 0.83mm Substance 920gm 2 Density 1100kgm' 3 Tensile Strength 4.2 MPa Compression at 34.5 MPa 14.3% Stress Relaxation 24.8% A conventional paper made according to GB 2250302 showed a stress relaxation of 42% by the same test method.
In additional to the above properties the ability of the paper to seal against a mixture of water and 50% antifreeze was measured. A sealing stress of 10.3 MPa was applied to an annular sample of the paper and the internal pressure of the water/antifreeze mixture increased in steps of 1 bar. Each pressure was held for a period of 5 minutes and the pressure at which leakage occurred was noted. Samples of the above paper were found to leak at an internal pressure of 2 bar.
SUBSTITUTE SHEET (RULE 26) WO 97/49864 PCT/GB97/01587 It was found that the sealing performance of the paper could be dramatically improved by impregnation of the paper with a silicone resin, such that a fluid pressure of 10 bar was sealed.
Example 2 A paper was prepared largely as described above from the following formulation.
by dry weight Fibrillated Aramid Fibre Pulp Calcined China Clay Attapulgite Colloidal Silica Nitrile Rubber The paper had the following properties: Thickness Substance Density Tensile Strength Compression at 34.5 MPa Stress Relaxation 0.65mm 860gm 2 1330kgm 3 7.0 MPa 15.3% 29.8% A sealing test was carried out as described above and the paper was found to seal an internal pressure of 10 bar without detectable leakage at a sealing stress of 10.3 MPa.
The paper also sealed 10 bar fluid pressure at a reduced sealing stress of 3.4 MPa.
SUBSTITUTE SHEET (RULE 26) Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification, they are to be interpreted as specifying the presence of the stated features, integers, steps or components referred to, but not to preclude the presence or addition of one or more other feature, integer, step, component or group thereof.
0* 0 Ce
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Claims (9)
1. A method of manufacture of a paper stock for dewatering to paper, comprising by weight 4-15% aramid fibre pulp, 60-90% silicate mineral, 4-10% polymeric binder and 2-15% inorganic binder, comprising the steps of mixing the aramid fibres in water to produce a slurry of about 2% solids content by weight diluting the pulp with water adding the silicate mineral to the mixture agitating the mixture further diluting the mixture with water to produce a slurry of about 4% solids content by weight adding a 10% solution of papermakers alum such that the dry content is about 1% of the total composition agitating the mixture adding to the mixture the inorganic binder adding to the mixture the polymeric binder having a solids content of about 50% by weight waiting until the polymeric binder is fully dispersed and adding a further quantity of the papermakers alum solution until the supematant liquid becomes clear.
2. A method according to claim 1 in which at least some of the silicate mineral added is constituted by a fibrous chain silicate.
3. A method according to claim 2 in which said added fibrous chain silicate is attapulgite.
4. A method according to any of claims 1-3 in which the silicate mineral added comprises a layered kaolinitic clay. A method according to claim 4 wherein the added clay comprises calcined china clay.
SUBSTITUTE SHEET (RULE 26) WO 97/49864 PCT/GB97/01S87 -7-
6. A method according to claim 5 wherein said added chain clay has been calcined at over 800 0 C.
7. A method according to any of claims 1-6 wherein the inorganic binder added is colloidal silica.
8. A method according to any preceding claim wherein the polymeric binder added is nitrile rubber.
9. A method according to any preceding claim comprising by weight 4-8% aramid fibre pulp, 5-8% polymeric binder, 75-90% silicate mineral, 4-10% inorganic binder. d SUBSTITUTE SHEET (RULE 26)
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9613456A GB2314569B (en) | 1996-06-27 | 1996-06-27 | Gasket paper |
GB9613456 | 1996-06-27 | ||
PCT/GB1997/001587 WO1997049864A1 (en) | 1996-06-27 | 1997-06-12 | Gasket paper |
Publications (2)
Publication Number | Publication Date |
---|---|
AU3099097A AU3099097A (en) | 1998-01-14 |
AU713243B2 true AU713243B2 (en) | 1999-11-25 |
Family
ID=10795958
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
AU30990/97A Ceased AU713243B2 (en) | 1996-06-27 | 1997-06-12 | Gasket paper |
Country Status (9)
Country | Link |
---|---|
EP (1) | EP0916001B1 (en) |
JP (1) | JP2000513053A (en) |
KR (1) | KR20000015807A (en) |
AU (1) | AU713243B2 (en) |
BR (1) | BR9709944A (en) |
DE (1) | DE69704947T2 (en) |
GB (1) | GB2314569B (en) |
WO (1) | WO1997049864A1 (en) |
ZA (1) | ZA975620B (en) |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE102011053389A1 (en) * | 2011-09-08 | 2013-03-14 | Elringklinger Ag | Sealing arrangement for use in control plate of automatic transmission, has sealing contour elements made of sealing paper and including height profile with height, which varies between minimum height regions and maximum height regions |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4271228A (en) * | 1980-02-04 | 1981-06-02 | Hollingsworth & Vose Company | Sheet material containing exfoliated vermiculite |
US4330442A (en) * | 1980-05-07 | 1982-05-18 | Armstrong World Industries, Inc. | Asbestos free gasket forming compositions |
GB2093474B (en) * | 1981-02-10 | 1984-10-24 | Texon Inc | High temperature resistant gasketing material incorporating organic fibers |
GB2138855B (en) * | 1983-04-27 | 1986-03-26 | T & N Materials Res Ltd | Gasket paper |
GB2138854B (en) * | 1983-04-27 | 1986-03-26 | T & N Materials Res Ltd | Gasket paper |
US4786670A (en) * | 1987-01-09 | 1988-11-22 | Lydall, Inc. | Compressible non-asbestos high-temperature sheet material usable for gaskets |
GB9025983D0 (en) * | 1990-11-29 | 1991-01-16 | T & N Technology Ltd | Non-asbestos flexible sheet material |
GB9106806D0 (en) * | 1991-04-02 | 1991-05-22 | T & N Technology Ltd | Non-asbestos flexible sheet material |
DE4113153A1 (en) * | 1991-04-23 | 1992-10-29 | Du Pont Int | INDUSTRIAL SEAL FOR USE WITH STEAM |
DE4122737A1 (en) * | 1991-07-10 | 1993-01-14 | Akzo Nv | COMPOSITION WITH SHORT FIBERS MADE OF ARAMID |
-
1996
- 1996-06-27 GB GB9613456A patent/GB2314569B/en not_active Expired - Fee Related
-
1997
- 1997-06-12 BR BR9709944A patent/BR9709944A/en unknown
- 1997-06-12 EP EP97926103A patent/EP0916001B1/en not_active Expired - Lifetime
- 1997-06-12 DE DE69704947T patent/DE69704947T2/en not_active Expired - Fee Related
- 1997-06-12 WO PCT/GB1997/001587 patent/WO1997049864A1/en not_active Application Discontinuation
- 1997-06-12 KR KR1019980709356A patent/KR20000015807A/en not_active Application Discontinuation
- 1997-06-12 AU AU30990/97A patent/AU713243B2/en not_active Ceased
- 1997-06-12 JP JP10502481A patent/JP2000513053A/en active Pending
- 1997-06-25 ZA ZA9705620A patent/ZA975620B/en unknown
Also Published As
Publication number | Publication date |
---|---|
EP0916001B1 (en) | 2001-05-23 |
EP0916001A1 (en) | 1999-05-19 |
GB2314569A (en) | 1998-01-07 |
AU3099097A (en) | 1998-01-14 |
KR20000015807A (en) | 2000-03-15 |
GB2314569B (en) | 2000-01-26 |
WO1997049864A1 (en) | 1997-12-31 |
BR9709944A (en) | 1999-08-10 |
ZA975620B (en) | 1997-12-29 |
JP2000513053A (en) | 2000-10-03 |
DE69704947D1 (en) | 2001-06-28 |
GB9613456D0 (en) | 1996-08-28 |
DE69704947T2 (en) | 2001-09-06 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
MK14 | Patent ceased section 143(a) (annual fees not paid) or expired |