CA1215488A - Gasket materials - Google Patents
Gasket materialsInfo
- Publication number
- CA1215488A CA1215488A CA000461232A CA461232A CA1215488A CA 1215488 A CA1215488 A CA 1215488A CA 000461232 A CA000461232 A CA 000461232A CA 461232 A CA461232 A CA 461232A CA 1215488 A CA1215488 A CA 1215488A
- Authority
- CA
- Canada
- Prior art keywords
- hereof
- set forth
- polyester
- parts
- rubbers
- 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.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L67/00—Compositions of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Compositions of derivatives of such polymers
- C08L67/02—Polyesters derived from dicarboxylic acids and dihydroxy compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L21/00—Compositions of unspecified rubbers
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L97/00—Compositions of lignin-containing materials
- C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
Abstract
IMPROVED GASKET MATERIALS
Abstract The present invention relates to gasketing materials comprising a rubber binder, a pulverized rice hull filler and a polyester which preferably is crystallizable. The rice hull material acts as a reinforcing filler and, in combination with the rubber and polyester, provides gasketing materials which demonstrate the ability to conform to flange irregularities. As a result, the gaskets demonstrate remarkable sealing capabilities. When they comprise nitrile rubbers, they are also resistant to fuel absorption.
Abstract The present invention relates to gasketing materials comprising a rubber binder, a pulverized rice hull filler and a polyester which preferably is crystallizable. The rice hull material acts as a reinforcing filler and, in combination with the rubber and polyester, provides gasketing materials which demonstrate the ability to conform to flange irregularities. As a result, the gaskets demonstrate remarkable sealing capabilities. When they comprise nitrile rubbers, they are also resistant to fuel absorption.
Description
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IMPROVED GASKET MATERIALS
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The present invention relates to gasketing materials and, more particularly, to gasketing materials which demonstrate improved performance characteristics.
5Background of the Invention -Gasketin~ materials are well known in the art -and they play an important role in all facets of every-day life. A gasket is a device or medium used to create and maintain a barrier against the transfer of fluids -10 across separable surfaces of a mechanical assembly that ::
do not move relative to each other. Many types of gasket materials are presently in use. For example, --asbestos-rubber, cellulose-rubber, cork composition, cork-rubber and rubber gaskets are all found in various -1~ phases of industry. --One of the most common types of gasketing is cork-rubber gasketing. Cork is a highly compressible material ~lhich lends itself to a wide -- variety of gasketing applications; nevertheless, it --suffers from certain defects. For example, cork is porous and tends to swell when exposed to fuel and other petroleum-based products. Another problem related to the use of cork is that it is a natural material which is in finite supply. In recent years, the cost of cork -25 has increased dramatically and this cost increase has -led to widespread industry attempts to find replacement materials which are effective, yet which are lower in -cost.
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IMPROVED GASKET MATERIALS
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The present invention relates to gasketing materials and, more particularly, to gasketing materials which demonstrate improved performance characteristics.
5Background of the Invention -Gasketin~ materials are well known in the art -and they play an important role in all facets of every-day life. A gasket is a device or medium used to create and maintain a barrier against the transfer of fluids -10 across separable surfaces of a mechanical assembly that ::
do not move relative to each other. Many types of gasket materials are presently in use. For example, --asbestos-rubber, cellulose-rubber, cork composition, cork-rubber and rubber gaskets are all found in various -1~ phases of industry. --One of the most common types of gasketing is cork-rubber gasketing. Cork is a highly compressible material ~lhich lends itself to a wide -- variety of gasketing applications; nevertheless, it --suffers from certain defects. For example, cork is porous and tends to swell when exposed to fuel and other petroleum-based products. Another problem related to the use of cork is that it is a natural material which is in finite supply. In recent years, the cost of cork -25 has increased dramatically and this cost increase has -led to widespread industry attempts to find replacement materials which are effective, yet which are lower in -cost.
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2 - LFM-7311 A filler material which has received increasing attention because of its low cost and availability is rice hylls, a by-product of rice refining. The individual rice hulls are light-weight fiberous materials which primarily contain cellulose, but which also comprise about 25% inorganic materials, much of which is silica.
Rice hulls have been used in animal feeds, in :-agriculture, as fuels, and as raw materials for the --10 production of carbon particles, organic and inorganic -chemicals, abrasives and refractory materials. In addition, they have been used as fillers for cements, building boards and the like. Nevertheless, they have not been used as cork substitutes in gasketing materials.
Despite widespread attempts to utilize rice :
hulls, the results have not been entirely satisfactory. -The art contains reports that rice hulls require --pretreatment with coupling and/or wetting agents in ---order to make them suitable for use as fillers. :--Alternative treatments have included the partial or complete incineration of the hulls to provide ash which -has been used as a filler. Ilevertheless, it has been found that such modifications increase the cost of the filler and often do not si~nificantly improve its 25 characteristics. -Accordingly, one objective of the present invention is to provide rice hull compositions wherein the rice hulls serve as replacements for conventional ;:
fillers. --Another objective of the present invention is --to provide low-cost gasketing materials which exhi~it -superior performance characteristics. -Yet another objective of the present invention - ~-is to provide gasketing materials which are adaptable to 35 conform to flange contours, thereby providing superior -:
seals.
Still yet another objective of the present -invention is to provide improved gasketing materials ....
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Rice hulls have been used in animal feeds, in :-agriculture, as fuels, and as raw materials for the --10 production of carbon particles, organic and inorganic -chemicals, abrasives and refractory materials. In addition, they have been used as fillers for cements, building boards and the like. Nevertheless, they have not been used as cork substitutes in gasketing materials.
Despite widespread attempts to utilize rice :
hulls, the results have not been entirely satisfactory. -The art contains reports that rice hulls require --pretreatment with coupling and/or wetting agents in ---order to make them suitable for use as fillers. :--Alternative treatments have included the partial or complete incineration of the hulls to provide ash which -has been used as a filler. Ilevertheless, it has been found that such modifications increase the cost of the filler and often do not si~nificantly improve its 25 characteristics. -Accordingly, one objective of the present invention is to provide rice hull compositions wherein the rice hulls serve as replacements for conventional ;:
fillers. --Another objective of the present invention is --to provide low-cost gasketing materials which exhi~it -superior performance characteristics. -Yet another objective of the present invention - ~-is to provide gasketing materials which are adaptable to 35 conform to flange contours, thereby providing superior -:
seals.
Still yet another objective of the present -invention is to provide improved gasketing materials ....
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- 3 - LFM-7311 which will be resistant to fuel absorption.
T~.ese and other objectives of the present invention will become apparent from the detailed description of preferred embodiments which follow.
Summary of the Invention --The present invention relates to gasketing materials comprising a rubber binder, a pulverized rice hull filler and a polyester which preferably is crystal- -lizable. The rice hull material acts as a reinforcing --filler and, in combination with the rubber and polyester, provides gasketing materials ~hich demonstrate the --ability to conform to flange irregularities. As a result, the gaskets demonstrate remarkable sealing capabilities. When they comprise nitrile rubbers, they -are also resistant to fuel absorption.
Detailed Description of Preferred Embodiments --~ In one embodiment, the present invention --relates to a cured gasket composition obtained from a -mixture comprising by weight 100 parts of a rubber --binder; from about 5 to about 100 parts of pulverized rice hulls; and from about 1 to about 200 parts of a -polyester having a weight -average molecular weight of from about 1,000 to about 500,000.
In a second embodiment, the present invention relates to a cured gasket composition obtained from a mixture comprising by weight 100 parts of a rubber binder; from about 5 to about 1,000 parts of pulverized --rice hulls; and from about 1 to about 200 parts of a crystallizable polyester having a weight average --molecular weight of from about 1,000 to about S00,000 and having a Tg of from about 50 to about +80 C, said binder and said polyester comprising a polymer blend which exhibits Tg's attributable to the polyester and to -the binder, said polyester comprising domains in which 35 said polyester is at least partially crystalline under -`
ambient conditions, but which can assume a substantially noncrystalline state in the operating environment of the gasket.
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~ 4 LFM-7311 In a third embodiment, the present invention relates to a process fo~ forming a gasket m~terial, said process comprising the steps of preparing a composition comprising by weight (a) 100 parts of a rubber binder;
(b) from about 5 to about 1,000 parts of pulverized rice hulls; and (c) from about 1 to about 200 parts of a -polyester having a weight average molecular weight of from about 1,000 to about 500,000; forming said -composition into a desired configuration; and curing 10 said formed composition. ----A curable rubber binder, pulverized rice hull filler and a polyester which preferably is crystalliz- -able will be required to practice the present invention. -Rubber binders are well known in the art and they have ---previously been used widely in preparing gasketing materials. Many types of rubber binders may be used to practice the present invention. Illustrative examples -of such binders are nitrile rubbers, SBR rubbers, cis-polybutadiene rubbers, butyl rubbers, cis-polyiso~
prene rubbers, EPDM rubbers, neoprene rubbers, silicone rubbers, fluorocarbon rubbers, and the like. Nitrile rubbers are presently in use in automotive gaskets ~-because of their resistance to oil, and they have been found to give superior results when used in practicing ` ~-the present invention. As an added consideration, the practice of the present invention is not restricted to -the use of a single rubber binder. Thus, combinations --....
of rubber binders may be used to give gaskets with specially modified properties.
The second required ingredient for practicing the present invention is a pulverized rice hull filler ---material. Rice hulls are typically sold in a -pulverized form and essentially all of the filler material used in practicing the presen~ invention should 'A''''.' 35 be capable of passing through a 30-mesh sieve (U.S. --Standard). Preferably, however, not more than about 5~
of the rice hulls will be larger than 80 mesh. No ---pretreatment with wetting or coupling agents is ---.....
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required. Although such pretreatmen~ may be used at the artisans discretion, for purposes of practicing the present invention, there appears to be little advantage in doing so. As will be indicated below, however, pretreatment with oil may be advantageous.
In addition to the rice hulls and rubber binder, the compositions will also comprise one or more polyesters which are derived by procedures well known in the art from monomeric diols and monomeric diacids or acid derivatives. Typical acid derivatives would include esters of low boiling alcohols and acid anhydrides. Preferably, the acid portion of the polyester will be aromatic or saturated aliphatic, although unsaturated acids such as fumaric or maleic acid can also be used. Simple diols are preferred when practicing the invention; however, polyether glycols may also be substituted for, or used in combination with, simple diols. As an added consideration, the polyester may be capped with acrylate and/or methacrylate groups by means well known in the art.
The aforementioned polyesters will have a -weight average minimum molecular weight of about 1,000 -and a weight average maximum molecular weight of about 500,000 as determined by gel permeation chromatography 25 using polystyrene calibration. Preferably, however, the .
molecular weight will range from about 2,000 to about 300,000, and most preferably from about 2,000 to about 50,000.
The most preferred composition for variable 30 temperature engine applications will comprise polyesters -.-having the foregoing characteristics wherein the polyesters are at least partially crystalline under ambient conditions. Thus, the polyester should have a Tg of from about -50 to about +80C. Preferably, however, the Tg should be from about -20 to about - +35C.
In order to be processable on conventional steam-heated mixing equipment, the polyester should be . . .
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capable of assuming a fluid condition during the mixing process whe-e the temperature approaches abo~t 300 F.
~referably it should b.e capable of being fl~id at about 270-28DF, which is the usually desired temperature range encountered during processing. The fluid state of the polyestçr is important because, in this state, the polyester often facilitates the blending of the rice hulls with the rubber binder. In the absence of polyester, prolonged mixing is required to mix the rice hulls with the rubber binder. In certain instances, such as with EPDM binder, oil extension may be required even in the presence of the polyester. Illustrative examples of commercially available polysters which are suitable to practice the present invention are Vitel VPE
4709, VPE 5571 and VPE 10035 polyesters from Goodyear Chemical Co.
Although rice hulls are not as compressible as cork, in ~he combination of the present invention 1hey have been shown to provide durable gasketing materials which are characterized by a smooth, yet leathery, feel.
The gaskets have excellent sealing properties and, in addition, they have shown a very good ability to recover or rebound to essentially their original thickness when the compressing force was removed. The good sealing capability appears to be obtainable because the laminar component of ground rice hulls can be aligned during the laying up process to provide sheets of material which have a smooth surface. Although alignment is not required, the smooth surface of an aligned product in combination with the reinforcing effect of the rice hull material tends to give products with high gas sealing ability. The reinforcing phenomenon may be attributable to the fibrous nature some of the ground rice hull particles, the presence of silica in the rice hulls, and/or the geometric shape of the ground rice hull particles. The latter characteristic may be of significance because rice hulls are distinguishable in performance from other natural productsO Thus, when '.
* Trademark ~S~38 other natural products such as peanut shell flour, ~ound corn cobs or wood flour which have little or no inherent particle geometry are substituted for rice hulls, lower quality gaskets are obtained.
One method of practicing the present invention is to place the rubber (which preferably is nitrile rubber), the rice hulls and the polyester in a mixer such as a Banbury mixer. Typically, the mixture will -comprise from about 1 to about 200 parts by weight of -polyester and from about 5 to about 1,000 parts by weight of rice hulls for every 100 parts by weight of rubber binder. Preferably, however, the mixture will comprise from about 10 to about 150 parts of polyester -and from about 50 to about 800 parts of rice hulls for every 100 parts of rubber binder.
The components are mixed until the temperature of the mixture reaches about 230 to 275F and the -:
temperature is then maintained until a desired mixing consistency is obtained. Prolonged heating at higher ---20 temperatures is not desired because the rubber binder --~
may tend to scorch.
~f the gasketing material is to be cured by -conventional techniques, a peroxide or a sulfur/accele-rator system can then be added and mixed. The latter -25 type of curing system is well known in the art and can -comprise activators such as zinc oxide and stearic acid; :
a primary accelerator such as a thiazole accelerator; a -secondary accelerator such as a thiuram accelerator; and -:
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a vulcanizing agent such as sulfur.
If non-conventional curing such as electron ---beam curing is used, no initiator is required; however, promoters may be added a~ an artisan's discretion~ -Examples of primary promoters are p-phenylene dimaleimide, N-phenylmaleimide and acrylate monomers;
however, secondary promoters such as chlorinated aromatics and soaps could also be used. --Other materials may also be added at the artisan's discretion, provided that they do not --. .
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adversely affect the quality of the product. For example, carbon black, tackifiers, processing oils, plasticizers, anti-oxidants, stabilizers, antiscorch agents and certain filler materials may be added under appropriate circumstances without adverse results.
After mixing is complete, the batch is dropped from the mixer and is calendered to sheet off the material. The sheet product is then cured by electron ::
beam, or by heating a sheet which comprises a conven- -tional sulfur/accelerator curing package. The cutting of the material into appropriate gaskets may be achieved either before or after the sheet is cured.
When using the conventional curing method, it has been found that temperatures of from about 325 to -about 335F are needed for at least 10-15 minutes in order to adequately cure the product. Lower tempera tures do not lead to an appropriate cure level. For -non-conventional electron beam curing, dosages of 12.5 Mrad have been found suitable. --The method of curing will usually lead to -products having different characteristics. For example, gasketing materials which are cured by exposure to an electron beam tend to have higher density values and tensile stréngths than do sulfur cured gasketing 25 materials. On the other hand, sulfur cured materials ---show a higher swell rate in water than do comparable -electron beam-cured sheets. In addition, electron beam-cured samples typically show a compressibility of less than about 8~ whereas sulfur cured samples give a compressibility of about 25~.
The method of curing will often be dictated by the end use for the gasket. When placed in contact with a liquid, a gasket preferably will swell sufficiently to give a good seal and prevent leaking, but it should not 35 swell so much that it is structurally weakened. In the -presence of water, it is common for cork-rubber gaskets to show swelling of the cork but not the binder;
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however, in the presence of fuel or oil, both the cork :
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- g - LFM-7311 and the binder typically are affected. As a result, hese gaskets often show a loss of structural integrity, and this has led to the use of high-priced substitutes, such as fluoroelastomer gaskets, in environments ~here the gaskets are in contact with petroleum based liquids.
Therefore, the use of electron beam curing may be pre- :
ferable for gaskets of the present invention which will be in contact with oil and/or fuel because swelling can often be held to acceptable limits. --As alternatives to the use of a mixer, the -components may be combined in a mill and then sheeted -off using calender rolls. In addition, the material may be extrusion mixed, such as by using a twin-screw extruder. Calendering and milling provide material with 15 surfaces in which the rice hulls are aligned; however, .--extrusion can also produce aligned hull surfaces, if properly handled. ~
Calendering is usually used to produce fairly thin sheets of material because very thick sheets may -20 tend not to adhere to the rolls and be non-uniform. .-Accordingly, if thicker materials are desired, it is preferable to prepare them by compression molding. -A gasket composition which is produced as described above is not a dispersion of rice hulls in a polymer solution, but rather is a mixture of rice hulls in a polymer blend which contains distinct polyester -domains. The existence of the domains can be confirmed by differential scanning calorimetry (DSC) measurements ---on mixtures of rubber binder and polyester. Thus, --30 rather than seeing a single Tg, as would be the case --with two compatible polymers which form a solution, two -distinct DSC transitions are seen which correspond to the Tg values for the rubber binder and the polyester, .-respectively. Furthermore, as heating is continued, an --35 endotherm attributable to the melting of the polyester ---crystals is seen. If the mixture is rapidly cooled and -~
then reheated, the endotherm is not seen because the .-polyester has not yet recrystallized; i.e., it -~.
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recrystallizes very slowly. Nevertheless, on standing, the polyester again assumes its partially crystalline character and the end~therm again becomes detectable by DSC analysis.
The uniqueness of the preferreu gasketing --materials which may be produced according to the present --invention can be attributed in part to the reinforcing --character of the rice hulls, which provides good reslstance to creep under load, and in part to the partial crystallinity of the polyester. For example, if the gasket is used as a valve cover gasket where it is exposed to engine oil, the partially crystalline -polyester will mel~ as the engine temperature increases, -thus allowing the gasket to adapt itself to the contours --15 of the flange. Further, the gasket has good tensile --strength at ambient conditions but, when the polyester --has melted, it tends to promote good adhesion with the flange. Upon cooling, the partially crystalline nature of the polyester domains is slowly reassumed~ This sequence is repeated during subsequent engine operation;
therefore, the gasket is able to continually adapt its -shape to any changes in flange pressure, and oil leakage is either eliminated or minimized.
Gaskets which may be produced according to the 25 present invention will find use in a variety of environ- -ments where they are exposed to water, oil and/or gas. --For low-pressure flange applications of from about :
50-300 psi they will function in a manner comparable to cork-rubber gaskets; however, for high flange pressures :-30 up to about 2000 psi they will function in a manner far --superior to cork-rubber because cork-rubber gaskets disintegrate more readily under such pressures. This ability to withstand high flange pressures is a surprising and unexpected result which is attributable --almost entirely to the reinforcing nature of the rice hulls (vide supra) The present invention may be more clearly understood by reference to the following examples which .....
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EXAMPLES
The following materials are used in the examples and are identified by alphabetical letter, Nitrile Rubber . Acrylonitrile Rubber DescriE~ion So~rce Content A 2000NMG Polysar 31.54%
B Paracril 1880 Uniroyal 22%
C Paracril CJLT ~niroyal 39~5 .
~PDM P~ubber Ethylene~Propylene Rubber Description SourceRatio _ _ D 505 EPDM Uniroyal 57/43 15 SBR Rubber .
.
Rubber DescriptionSource Bo~nd Styrene (%) E 1502 SBRPolysar 23.5 Polyesters Polyester Description Source Components A Polyester 605 Armstrong Terephthalic Acid Tg=-1C (experimental) (12.0 eq.), Azelaic Acid Cryst. MP by DSC (8.0 eg.), =153 and 180CEthylene glycol ~6.0 eq.), Cyclohexane dimethanol-R90 (14.0 ~q.~, and 1,6-Hexane-diol ~5.0 eq.) B Polyester 751Armstrong Terephthalic Acid Tg=-5DC (experimental) (10.0 eq.), Azelaic Acid ,,~, .
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~ 12 - LFM-7311 Pol~ester Description Source Components Cryst. MP by DSC (10.0 eq.) = 145C Ethylene glycol (8.0 eq.) Cyclohexane dimethanol-R90 (15.0 eq.) and 1,6-Hexane-diol (2.0 eq.) C Vitel VPE4709 Goodyear Chem. Terephthalic Acid, ~g = 22 + 6C Isophthalic Acid Cryst. MP by DSC=130+ 7C and 1,4-Butanediol D Vitel VPE5571A Goodyear Chem. Azelaic Acid, Tg = -5 + 6C Terephthalic acid Cryst. MP by DSC=150~ 8C and Ethylene -glycol A general preparative procedure which may be -used to prepare experimental polyesters 605 and 751 is as follows: A 3-liter round-bottom flask is equipped 20 with a packed steam-heated condenser, a stirrer, a -nitrogen inlet and a thermometer. The applicable components (the acids, the glycols/diols and an -appropriate catalyst such as Fastcat 2001 tin catalyst) -are charged into the flask and the mixture is s~irred and heated until the temperature reaches 230 C~ During the heating process, the nitrogen flow is increased until it reaches about 1.5 SCFH (Standard Cubic Feet per -Hour). The distillate is collected and, when the volume -has reached approximately 85~ of the expected 438 gram 30 quantity, the acid number is monitored until it has -dropped to less than 1Ø Excess glycol is then removed -and the molecular weight is increased by evacuating the -flask to less than 5 millimeters pressure and gradually increasing the temperature to 2Ç0 C. After the temperature has reached this value, the pressure is slowly decreased to less than 3 millimeters and then . . .
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~ 13 - LEM-7311 held until the mixture in the flask becomes too thick to stir, or until it is obvious that no useful change is occurring. The theoretically expe~ted amount of distillate is 155 grams. The resulting polyester is partially cooled and then poured into a Teflon lined Pyrex dish.
Rice Hulls Rice hulls were obtained from Multifil International, Inc. under the name Eiber X. A sieve analysis of typical material gave the following results using ~.S. Standard sieves:
~100 Mesh 5~ --t200 Mesh20%
~325 Mesh 45 -325 Mesh 55 Curing Accelerators The curing accelerators used for conventional curing of the gasketing materials contained the components listed below, based on 380 grams of rubber binder.
Component Weight (grams ?
Zinc oxide (Actox 16) activator 15 Stearic acid activator 3 ALTAX (MBTS) primary accelerator 4.5 25 TMTD (Methyl TUADS) secondary accelerator 1.5 Sulphur RM-99 vulcanizing agent 4.5 Component (for EPDM mixtures only)Weight (grams) "inc oxi~e (Actox 16) activator 14.0 Stearic acid activator 2.8 Royalac 133 primary accelerator 2.24 Diphenylguanidine secondary accelerator 0.34 Sulfur RM-99 vulcanizing agent 3.5 .~ .
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, * Trademark - l4 - LFM-7311 Component (for SBR mixtures only) Weight (grams) Zinc oxide (Actox 16) activator 14.0 S~earic acid activator 2.
ALTAX (MBTS) primary accelerator 4.2 5 TMTD (Methyl TUADS) secondary accelerator 1.4 Sulfur RM-99 vulcanizing agent 4.2 The ALTAX is benzothiazyl disulfide, a thiazole accelerator, the TMTD is a thiuram accelerator, --and the Royalac 133 is a dithiocarbamate/thiazole blend. -:
All of these accelerators are well known in the art.
Example I
This example will illustrate the physical characteristics of gasketing materials which are obtained when different nitrile rubbers are mixed with rice hulls and polyester A. Percentage values for the components are given in weight percent. All samples were cured by exposure to an electron beam for 11 minutes at a dosage level of 12.5 Mrad. All samples -contained 1~ Scorchgard 0 to stabilize the rubber during mixing. The sheets which were obtained were tough and had a smooth, leathery feel.
By reference to the Table, Examples IA-IC
illustrate that reducing the amount of nitrile rubber A
and increasing the amount of polyester A caused a reduction in compressability, but an increase in hardness.
In addition, the tensile strength increased, but the ~-swelling in water, Fuel C and ASTM $3 oil decreased.
Similar changes were noted for Nitrile B
~Examples ID and IE) and Nitrile C (Examples IF and IG) 30 when polyester A was eliminated. Especially -:
significant, however, was the effect of polyester in Example IF. This example showed a remarkable low swelling in Fuel C of only ~%.
As previously indicatedl the polyester helps to faciliate the mixing of the rice hulls; thus, Examples IC, IE and IG which contained no polyester were --difficult to mix.
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This example will illustrate mixtures of ~itrile ~ with rice h~lls and various polyesters. The products were cured either by exposure to electron beam or by conventional curing, as indicated. All samples contained 1~ Scorchgard 0, and Examples IIA, IIC and IIE, which were sulfur cured, contained 2.6% by weight of the accelerator package described above.
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~ 18 - LFM-7311 Example III
This example will illustrate the effect of various additives on Composltions comprising nitrile rubber A~ polyester A and rice hulls. For comparison, reference is made to Example IA. All samples were cured by electron beam and contained 1% Scorchgard 0.
Examples IIIC and IIIF also illustrate that, in this system, increasing the amount of rice hulls increases the tensile strength and hardness of the product.
Norsorex is a polynorbornene which is used as a rubber additive. Vestenamer is a high trans oontent polyoctenamer which is used as a processing aid and to reduce swelling of rubber goods in water. RB-830 is a 1,2-syndiotactic polybutadiene which is sensitive to radiation curing.
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~ his example will illustrate EPDM rub~er, polyester and rice hull compositions. The N-220 carbon was o~tained from Phillips Petroleum and is ~ very fine particle-size material which is known as a reinforcing black7 However, by comparison to samples IVA and IVB, the carbon appears t~ have little reinforcing effect for compositions of the present invention.
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T~.ese and other objectives of the present invention will become apparent from the detailed description of preferred embodiments which follow.
Summary of the Invention --The present invention relates to gasketing materials comprising a rubber binder, a pulverized rice hull filler and a polyester which preferably is crystal- -lizable. The rice hull material acts as a reinforcing --filler and, in combination with the rubber and polyester, provides gasketing materials ~hich demonstrate the --ability to conform to flange irregularities. As a result, the gaskets demonstrate remarkable sealing capabilities. When they comprise nitrile rubbers, they -are also resistant to fuel absorption.
Detailed Description of Preferred Embodiments --~ In one embodiment, the present invention --relates to a cured gasket composition obtained from a -mixture comprising by weight 100 parts of a rubber --binder; from about 5 to about 100 parts of pulverized rice hulls; and from about 1 to about 200 parts of a -polyester having a weight -average molecular weight of from about 1,000 to about 500,000.
In a second embodiment, the present invention relates to a cured gasket composition obtained from a mixture comprising by weight 100 parts of a rubber binder; from about 5 to about 1,000 parts of pulverized --rice hulls; and from about 1 to about 200 parts of a crystallizable polyester having a weight average --molecular weight of from about 1,000 to about S00,000 and having a Tg of from about 50 to about +80 C, said binder and said polyester comprising a polymer blend which exhibits Tg's attributable to the polyester and to -the binder, said polyester comprising domains in which 35 said polyester is at least partially crystalline under -`
ambient conditions, but which can assume a substantially noncrystalline state in the operating environment of the gasket.
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~ 4 LFM-7311 In a third embodiment, the present invention relates to a process fo~ forming a gasket m~terial, said process comprising the steps of preparing a composition comprising by weight (a) 100 parts of a rubber binder;
(b) from about 5 to about 1,000 parts of pulverized rice hulls; and (c) from about 1 to about 200 parts of a -polyester having a weight average molecular weight of from about 1,000 to about 500,000; forming said -composition into a desired configuration; and curing 10 said formed composition. ----A curable rubber binder, pulverized rice hull filler and a polyester which preferably is crystalliz- -able will be required to practice the present invention. -Rubber binders are well known in the art and they have ---previously been used widely in preparing gasketing materials. Many types of rubber binders may be used to practice the present invention. Illustrative examples -of such binders are nitrile rubbers, SBR rubbers, cis-polybutadiene rubbers, butyl rubbers, cis-polyiso~
prene rubbers, EPDM rubbers, neoprene rubbers, silicone rubbers, fluorocarbon rubbers, and the like. Nitrile rubbers are presently in use in automotive gaskets ~-because of their resistance to oil, and they have been found to give superior results when used in practicing ` ~-the present invention. As an added consideration, the practice of the present invention is not restricted to -the use of a single rubber binder. Thus, combinations --....
of rubber binders may be used to give gaskets with specially modified properties.
The second required ingredient for practicing the present invention is a pulverized rice hull filler ---material. Rice hulls are typically sold in a -pulverized form and essentially all of the filler material used in practicing the presen~ invention should 'A''''.' 35 be capable of passing through a 30-mesh sieve (U.S. --Standard). Preferably, however, not more than about 5~
of the rice hulls will be larger than 80 mesh. No ---pretreatment with wetting or coupling agents is ---.....
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required. Although such pretreatmen~ may be used at the artisans discretion, for purposes of practicing the present invention, there appears to be little advantage in doing so. As will be indicated below, however, pretreatment with oil may be advantageous.
In addition to the rice hulls and rubber binder, the compositions will also comprise one or more polyesters which are derived by procedures well known in the art from monomeric diols and monomeric diacids or acid derivatives. Typical acid derivatives would include esters of low boiling alcohols and acid anhydrides. Preferably, the acid portion of the polyester will be aromatic or saturated aliphatic, although unsaturated acids such as fumaric or maleic acid can also be used. Simple diols are preferred when practicing the invention; however, polyether glycols may also be substituted for, or used in combination with, simple diols. As an added consideration, the polyester may be capped with acrylate and/or methacrylate groups by means well known in the art.
The aforementioned polyesters will have a -weight average minimum molecular weight of about 1,000 -and a weight average maximum molecular weight of about 500,000 as determined by gel permeation chromatography 25 using polystyrene calibration. Preferably, however, the .
molecular weight will range from about 2,000 to about 300,000, and most preferably from about 2,000 to about 50,000.
The most preferred composition for variable 30 temperature engine applications will comprise polyesters -.-having the foregoing characteristics wherein the polyesters are at least partially crystalline under ambient conditions. Thus, the polyester should have a Tg of from about -50 to about +80C. Preferably, however, the Tg should be from about -20 to about - +35C.
In order to be processable on conventional steam-heated mixing equipment, the polyester should be . . .
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capable of assuming a fluid condition during the mixing process whe-e the temperature approaches abo~t 300 F.
~referably it should b.e capable of being fl~id at about 270-28DF, which is the usually desired temperature range encountered during processing. The fluid state of the polyestçr is important because, in this state, the polyester often facilitates the blending of the rice hulls with the rubber binder. In the absence of polyester, prolonged mixing is required to mix the rice hulls with the rubber binder. In certain instances, such as with EPDM binder, oil extension may be required even in the presence of the polyester. Illustrative examples of commercially available polysters which are suitable to practice the present invention are Vitel VPE
4709, VPE 5571 and VPE 10035 polyesters from Goodyear Chemical Co.
Although rice hulls are not as compressible as cork, in ~he combination of the present invention 1hey have been shown to provide durable gasketing materials which are characterized by a smooth, yet leathery, feel.
The gaskets have excellent sealing properties and, in addition, they have shown a very good ability to recover or rebound to essentially their original thickness when the compressing force was removed. The good sealing capability appears to be obtainable because the laminar component of ground rice hulls can be aligned during the laying up process to provide sheets of material which have a smooth surface. Although alignment is not required, the smooth surface of an aligned product in combination with the reinforcing effect of the rice hull material tends to give products with high gas sealing ability. The reinforcing phenomenon may be attributable to the fibrous nature some of the ground rice hull particles, the presence of silica in the rice hulls, and/or the geometric shape of the ground rice hull particles. The latter characteristic may be of significance because rice hulls are distinguishable in performance from other natural productsO Thus, when '.
* Trademark ~S~38 other natural products such as peanut shell flour, ~ound corn cobs or wood flour which have little or no inherent particle geometry are substituted for rice hulls, lower quality gaskets are obtained.
One method of practicing the present invention is to place the rubber (which preferably is nitrile rubber), the rice hulls and the polyester in a mixer such as a Banbury mixer. Typically, the mixture will -comprise from about 1 to about 200 parts by weight of -polyester and from about 5 to about 1,000 parts by weight of rice hulls for every 100 parts by weight of rubber binder. Preferably, however, the mixture will comprise from about 10 to about 150 parts of polyester -and from about 50 to about 800 parts of rice hulls for every 100 parts of rubber binder.
The components are mixed until the temperature of the mixture reaches about 230 to 275F and the -:
temperature is then maintained until a desired mixing consistency is obtained. Prolonged heating at higher ---20 temperatures is not desired because the rubber binder --~
may tend to scorch.
~f the gasketing material is to be cured by -conventional techniques, a peroxide or a sulfur/accele-rator system can then be added and mixed. The latter -25 type of curing system is well known in the art and can -comprise activators such as zinc oxide and stearic acid; :
a primary accelerator such as a thiazole accelerator; a -secondary accelerator such as a thiuram accelerator; and -:
.
a vulcanizing agent such as sulfur.
If non-conventional curing such as electron ---beam curing is used, no initiator is required; however, promoters may be added a~ an artisan's discretion~ -Examples of primary promoters are p-phenylene dimaleimide, N-phenylmaleimide and acrylate monomers;
however, secondary promoters such as chlorinated aromatics and soaps could also be used. --Other materials may also be added at the artisan's discretion, provided that they do not --. .
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adversely affect the quality of the product. For example, carbon black, tackifiers, processing oils, plasticizers, anti-oxidants, stabilizers, antiscorch agents and certain filler materials may be added under appropriate circumstances without adverse results.
After mixing is complete, the batch is dropped from the mixer and is calendered to sheet off the material. The sheet product is then cured by electron ::
beam, or by heating a sheet which comprises a conven- -tional sulfur/accelerator curing package. The cutting of the material into appropriate gaskets may be achieved either before or after the sheet is cured.
When using the conventional curing method, it has been found that temperatures of from about 325 to -about 335F are needed for at least 10-15 minutes in order to adequately cure the product. Lower tempera tures do not lead to an appropriate cure level. For -non-conventional electron beam curing, dosages of 12.5 Mrad have been found suitable. --The method of curing will usually lead to -products having different characteristics. For example, gasketing materials which are cured by exposure to an electron beam tend to have higher density values and tensile stréngths than do sulfur cured gasketing 25 materials. On the other hand, sulfur cured materials ---show a higher swell rate in water than do comparable -electron beam-cured sheets. In addition, electron beam-cured samples typically show a compressibility of less than about 8~ whereas sulfur cured samples give a compressibility of about 25~.
The method of curing will often be dictated by the end use for the gasket. When placed in contact with a liquid, a gasket preferably will swell sufficiently to give a good seal and prevent leaking, but it should not 35 swell so much that it is structurally weakened. In the -presence of water, it is common for cork-rubber gaskets to show swelling of the cork but not the binder;
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however, in the presence of fuel or oil, both the cork :
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- g - LFM-7311 and the binder typically are affected. As a result, hese gaskets often show a loss of structural integrity, and this has led to the use of high-priced substitutes, such as fluoroelastomer gaskets, in environments ~here the gaskets are in contact with petroleum based liquids.
Therefore, the use of electron beam curing may be pre- :
ferable for gaskets of the present invention which will be in contact with oil and/or fuel because swelling can often be held to acceptable limits. --As alternatives to the use of a mixer, the -components may be combined in a mill and then sheeted -off using calender rolls. In addition, the material may be extrusion mixed, such as by using a twin-screw extruder. Calendering and milling provide material with 15 surfaces in which the rice hulls are aligned; however, .--extrusion can also produce aligned hull surfaces, if properly handled. ~
Calendering is usually used to produce fairly thin sheets of material because very thick sheets may -20 tend not to adhere to the rolls and be non-uniform. .-Accordingly, if thicker materials are desired, it is preferable to prepare them by compression molding. -A gasket composition which is produced as described above is not a dispersion of rice hulls in a polymer solution, but rather is a mixture of rice hulls in a polymer blend which contains distinct polyester -domains. The existence of the domains can be confirmed by differential scanning calorimetry (DSC) measurements ---on mixtures of rubber binder and polyester. Thus, --30 rather than seeing a single Tg, as would be the case --with two compatible polymers which form a solution, two -distinct DSC transitions are seen which correspond to the Tg values for the rubber binder and the polyester, .-respectively. Furthermore, as heating is continued, an --35 endotherm attributable to the melting of the polyester ---crystals is seen. If the mixture is rapidly cooled and -~
then reheated, the endotherm is not seen because the .-polyester has not yet recrystallized; i.e., it -~.
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recrystallizes very slowly. Nevertheless, on standing, the polyester again assumes its partially crystalline character and the end~therm again becomes detectable by DSC analysis.
The uniqueness of the preferreu gasketing --materials which may be produced according to the present --invention can be attributed in part to the reinforcing --character of the rice hulls, which provides good reslstance to creep under load, and in part to the partial crystallinity of the polyester. For example, if the gasket is used as a valve cover gasket where it is exposed to engine oil, the partially crystalline -polyester will mel~ as the engine temperature increases, -thus allowing the gasket to adapt itself to the contours --15 of the flange. Further, the gasket has good tensile --strength at ambient conditions but, when the polyester --has melted, it tends to promote good adhesion with the flange. Upon cooling, the partially crystalline nature of the polyester domains is slowly reassumed~ This sequence is repeated during subsequent engine operation;
therefore, the gasket is able to continually adapt its -shape to any changes in flange pressure, and oil leakage is either eliminated or minimized.
Gaskets which may be produced according to the 25 present invention will find use in a variety of environ- -ments where they are exposed to water, oil and/or gas. --For low-pressure flange applications of from about :
50-300 psi they will function in a manner comparable to cork-rubber gaskets; however, for high flange pressures :-30 up to about 2000 psi they will function in a manner far --superior to cork-rubber because cork-rubber gaskets disintegrate more readily under such pressures. This ability to withstand high flange pressures is a surprising and unexpected result which is attributable --almost entirely to the reinforcing nature of the rice hulls (vide supra) The present invention may be more clearly understood by reference to the following examples which .....
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~ LFM-7311 are provided by way of ill~stration and not limitation.
EXAMPLES
The following materials are used in the examples and are identified by alphabetical letter, Nitrile Rubber . Acrylonitrile Rubber DescriE~ion So~rce Content A 2000NMG Polysar 31.54%
B Paracril 1880 Uniroyal 22%
C Paracril CJLT ~niroyal 39~5 .
~PDM P~ubber Ethylene~Propylene Rubber Description SourceRatio _ _ D 505 EPDM Uniroyal 57/43 15 SBR Rubber .
.
Rubber DescriptionSource Bo~nd Styrene (%) E 1502 SBRPolysar 23.5 Polyesters Polyester Description Source Components A Polyester 605 Armstrong Terephthalic Acid Tg=-1C (experimental) (12.0 eq.), Azelaic Acid Cryst. MP by DSC (8.0 eg.), =153 and 180CEthylene glycol ~6.0 eq.), Cyclohexane dimethanol-R90 (14.0 ~q.~, and 1,6-Hexane-diol ~5.0 eq.) B Polyester 751Armstrong Terephthalic Acid Tg=-5DC (experimental) (10.0 eq.), Azelaic Acid ,,~, .
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~ 12 - LFM-7311 Pol~ester Description Source Components Cryst. MP by DSC (10.0 eq.) = 145C Ethylene glycol (8.0 eq.) Cyclohexane dimethanol-R90 (15.0 eq.) and 1,6-Hexane-diol (2.0 eq.) C Vitel VPE4709 Goodyear Chem. Terephthalic Acid, ~g = 22 + 6C Isophthalic Acid Cryst. MP by DSC=130+ 7C and 1,4-Butanediol D Vitel VPE5571A Goodyear Chem. Azelaic Acid, Tg = -5 + 6C Terephthalic acid Cryst. MP by DSC=150~ 8C and Ethylene -glycol A general preparative procedure which may be -used to prepare experimental polyesters 605 and 751 is as follows: A 3-liter round-bottom flask is equipped 20 with a packed steam-heated condenser, a stirrer, a -nitrogen inlet and a thermometer. The applicable components (the acids, the glycols/diols and an -appropriate catalyst such as Fastcat 2001 tin catalyst) -are charged into the flask and the mixture is s~irred and heated until the temperature reaches 230 C~ During the heating process, the nitrogen flow is increased until it reaches about 1.5 SCFH (Standard Cubic Feet per -Hour). The distillate is collected and, when the volume -has reached approximately 85~ of the expected 438 gram 30 quantity, the acid number is monitored until it has -dropped to less than 1Ø Excess glycol is then removed -and the molecular weight is increased by evacuating the -flask to less than 5 millimeters pressure and gradually increasing the temperature to 2Ç0 C. After the temperature has reached this value, the pressure is slowly decreased to less than 3 millimeters and then . . .
. . .
~ 13 - LEM-7311 held until the mixture in the flask becomes too thick to stir, or until it is obvious that no useful change is occurring. The theoretically expe~ted amount of distillate is 155 grams. The resulting polyester is partially cooled and then poured into a Teflon lined Pyrex dish.
Rice Hulls Rice hulls were obtained from Multifil International, Inc. under the name Eiber X. A sieve analysis of typical material gave the following results using ~.S. Standard sieves:
~100 Mesh 5~ --t200 Mesh20%
~325 Mesh 45 -325 Mesh 55 Curing Accelerators The curing accelerators used for conventional curing of the gasketing materials contained the components listed below, based on 380 grams of rubber binder.
Component Weight (grams ?
Zinc oxide (Actox 16) activator 15 Stearic acid activator 3 ALTAX (MBTS) primary accelerator 4.5 25 TMTD (Methyl TUADS) secondary accelerator 1.5 Sulphur RM-99 vulcanizing agent 4.5 Component (for EPDM mixtures only)Weight (grams) "inc oxi~e (Actox 16) activator 14.0 Stearic acid activator 2.8 Royalac 133 primary accelerator 2.24 Diphenylguanidine secondary accelerator 0.34 Sulfur RM-99 vulcanizing agent 3.5 .~ .
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, * Trademark - l4 - LFM-7311 Component (for SBR mixtures only) Weight (grams) Zinc oxide (Actox 16) activator 14.0 S~earic acid activator 2.
ALTAX (MBTS) primary accelerator 4.2 5 TMTD (Methyl TUADS) secondary accelerator 1.4 Sulfur RM-99 vulcanizing agent 4.2 The ALTAX is benzothiazyl disulfide, a thiazole accelerator, the TMTD is a thiuram accelerator, --and the Royalac 133 is a dithiocarbamate/thiazole blend. -:
All of these accelerators are well known in the art.
Example I
This example will illustrate the physical characteristics of gasketing materials which are obtained when different nitrile rubbers are mixed with rice hulls and polyester A. Percentage values for the components are given in weight percent. All samples were cured by exposure to an electron beam for 11 minutes at a dosage level of 12.5 Mrad. All samples -contained 1~ Scorchgard 0 to stabilize the rubber during mixing. The sheets which were obtained were tough and had a smooth, leathery feel.
By reference to the Table, Examples IA-IC
illustrate that reducing the amount of nitrile rubber A
and increasing the amount of polyester A caused a reduction in compressability, but an increase in hardness.
In addition, the tensile strength increased, but the ~-swelling in water, Fuel C and ASTM $3 oil decreased.
Similar changes were noted for Nitrile B
~Examples ID and IE) and Nitrile C (Examples IF and IG) 30 when polyester A was eliminated. Especially -:
significant, however, was the effect of polyester in Example IF. This example showed a remarkable low swelling in Fuel C of only ~%.
As previously indicatedl the polyester helps to faciliate the mixing of the rice hulls; thus, Examples IC, IE and IG which contained no polyester were --difficult to mix.
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This example will illustrate mixtures of ~itrile ~ with rice h~lls and various polyesters. The products were cured either by exposure to electron beam or by conventional curing, as indicated. All samples contained 1~ Scorchgard 0, and Examples IIA, IIC and IIE, which were sulfur cured, contained 2.6% by weight of the accelerator package described above.
It is noted that with all samples the use of electron bealn curing resulted in an increase in tensile strength and density. On the other hand, the samples which were conventionally cured showed generally better compressibility, and better swelling in water.
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~ 18 - LFM-7311 Example III
This example will illustrate the effect of various additives on Composltions comprising nitrile rubber A~ polyester A and rice hulls. For comparison, reference is made to Example IA. All samples were cured by electron beam and contained 1% Scorchgard 0.
Examples IIIC and IIIF also illustrate that, in this system, increasing the amount of rice hulls increases the tensile strength and hardness of the product.
Norsorex is a polynorbornene which is used as a rubber additive. Vestenamer is a high trans oontent polyoctenamer which is used as a processing aid and to reduce swelling of rubber goods in water. RB-830 is a 1,2-syndiotactic polybutadiene which is sensitive to radiation curing.
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~ his example will illustrate EPDM rub~er, polyester and rice hull compositions. The N-220 carbon was o~tained from Phillips Petroleum and is ~ very fine particle-size material which is known as a reinforcing black7 However, by comparison to samples IVA and IVB, the carbon appears t~ have little reinforcing effect for compositions of the present invention.
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12~1L548~
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Ex2mple VI
This example illustrates compositions comprising EPDM rubbers and EPDM-nitrile rubber blends.
Example IVA and IVB are included in the .table for referenceO The table shows that EPDM and SBR rubber gaske~ing had significantly higher swell rates than did nitrile rubber gasketin~ when exposed to Fuel C or ASTM
No. 3 oil. It is also noted that, when the amount of rice hull filler exceeds about 60~ (as in VIF), a sheet product cannot be readily formed unless a processing oil, such as Circosal 480 Oil, is added. The processing oil, however, contributes to high s-~ell rates in ASTM
No. 3 oil.
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Example VII
This example will illustrate the performance of a gasket prepared.according to the present invention when it was exposed in an operating engine to engine oil at about 250-275 F. for 350 hours. The engine used for the test was a 1980 Chevrolet Chevette 1.6 L4 engine, which has an overhead cam design. The internal engine pressure during the test was 2-4 psi.
Gasket IIIE was used as a front cover gasket -and the flange pressure typically varied from about 50 to about 300 psi. The gasket thickness was 0.08 inch and its performance was comparable to Armstrong's -commercial cork-nitrile rubber gaskets YF-334, XC-300 -and NK-730. However, when the flange pressure was 15 increased to about 1,000 psi, gasket IIIE tolerated the -added pressure whereas the cork-rubber gaskets could -not.
Example VIII
This example will illustrate the performance of gasket IIID when it was used as a water pump gasket and as a thermostat housing gasket in the same Chevette --engine. The flange pressures varied from about 300 to 2,000 psi, which was too high for cork gaskets, and the cooling system temperature was about 200 F. The gaskets performed satisactorily for 115 hours, at which point the test was terminated. --EXAMPLE IX
This example will illustrate the results when -rice hulls were treated wi~h various materials. Examples -IXA and IXB are samples in which the rice hulls were treated with vinyl triethoxy silane sold as A-151 Silane by Union Carbide. For reference, untreated samples IA -and IC, respectively, are included in the table. Oil treated rice hulls were also used in sample IXC, and the 35 gasket material was compared to Example IIA in which the 'E
rice hulls were untreated. The oil-treated rice hulls were obtained from Riceland Foods and were designated by ....................................................................
,.. , ... , , .,, .................... ;.. .
,.. ... . .. ......... . .. . .. .......... ........ ...... .... .. .... .. ..... ..........
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sieve size as being -80 mesh. They were reported to contair. 1~ soybean oil as a dust suppressant. Examples IA, IC, IX~ and IXB were cured by electron beam whereas Examples IIA and IXC were sulfur cured.
As a basis for cbmparison, the table also ~
contains data for several commercial gaskets, all of which are sulfur cured. Gaskets NC 710 and NC 711 are :
high quality gaskets which are substantially more expensive than the gaskets of the present invention. :-The NC 757 and NC 775 gaskets are less expensive, but show correspondingly poorer compressibility and recovery --values. In addition, they also show significant increase in swell values for ASTM $3 oil. .-.
.
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,,,,,,,,,,,,,,,,,,,,,.,, ,,,,,,,, ,, .. ,.. ,.,.,.. ,. ,,,,,,.,,,,, ,,:,:, EXAMPLE X
This example will illustrate the gas sealing capability of nitrile r~bber-containing gaskets of the present invention in comparison to sealing capabilities which are typically demonstrated by common cork-rubber gasket compositions. The gas leakage test is conducted using an electromechanical air-leakage tester according to procedures which are known in the art. The results also illustrate that if gas sealing is a desirable ~--gasket feature, pretreatment of the rice hulls with soybean oil (as illustrated in Example IXC), or other oil, may be advisable.
:
Flange Leakage -Pressure Rate -15 Sample (PSI) (PSI/Min.) . --.
Cork-rubber 200 1.00 --500 0.01 --IA 230 0.34 -350 0.05 E
IIA 230 0.25 ~--350 0.01 ~
.
IXC 230 0.09 --350 0.005 460 0.001 .
Our invention is not restricted solely to the -descriptions and illustrations provided above, but encompasses all modification envisaged by the following claims. :-....
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12~1L548~
.
Ex2mple VI
This example illustrates compositions comprising EPDM rubbers and EPDM-nitrile rubber blends.
Example IVA and IVB are included in the .table for referenceO The table shows that EPDM and SBR rubber gaske~ing had significantly higher swell rates than did nitrile rubber gasketin~ when exposed to Fuel C or ASTM
No. 3 oil. It is also noted that, when the amount of rice hull filler exceeds about 60~ (as in VIF), a sheet product cannot be readily formed unless a processing oil, such as Circosal 480 Oil, is added. The processing oil, however, contributes to high s-~ell rates in ASTM
No. 3 oil.
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s~
Example VII
This example will illustrate the performance of a gasket prepared.according to the present invention when it was exposed in an operating engine to engine oil at about 250-275 F. for 350 hours. The engine used for the test was a 1980 Chevrolet Chevette 1.6 L4 engine, which has an overhead cam design. The internal engine pressure during the test was 2-4 psi.
Gasket IIIE was used as a front cover gasket -and the flange pressure typically varied from about 50 to about 300 psi. The gasket thickness was 0.08 inch and its performance was comparable to Armstrong's -commercial cork-nitrile rubber gaskets YF-334, XC-300 -and NK-730. However, when the flange pressure was 15 increased to about 1,000 psi, gasket IIIE tolerated the -added pressure whereas the cork-rubber gaskets could -not.
Example VIII
This example will illustrate the performance of gasket IIID when it was used as a water pump gasket and as a thermostat housing gasket in the same Chevette --engine. The flange pressures varied from about 300 to 2,000 psi, which was too high for cork gaskets, and the cooling system temperature was about 200 F. The gaskets performed satisactorily for 115 hours, at which point the test was terminated. --EXAMPLE IX
This example will illustrate the results when -rice hulls were treated wi~h various materials. Examples -IXA and IXB are samples in which the rice hulls were treated with vinyl triethoxy silane sold as A-151 Silane by Union Carbide. For reference, untreated samples IA -and IC, respectively, are included in the table. Oil treated rice hulls were also used in sample IXC, and the 35 gasket material was compared to Example IIA in which the 'E
rice hulls were untreated. The oil-treated rice hulls were obtained from Riceland Foods and were designated by ....................................................................
,.. , ... , , .,, .................... ;.. .
,.. ... . .. ......... . .. . .. .......... ........ ...... .... .. .... .. ..... ..........
1~?1S 4 ~
sieve size as being -80 mesh. They were reported to contair. 1~ soybean oil as a dust suppressant. Examples IA, IC, IX~ and IXB were cured by electron beam whereas Examples IIA and IXC were sulfur cured.
As a basis for cbmparison, the table also ~
contains data for several commercial gaskets, all of which are sulfur cured. Gaskets NC 710 and NC 711 are :
high quality gaskets which are substantially more expensive than the gaskets of the present invention. :-The NC 757 and NC 775 gaskets are less expensive, but show correspondingly poorer compressibility and recovery --values. In addition, they also show significant increase in swell values for ASTM $3 oil. .-.
.
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, ~ v O~ou~ ~ ~~ E E ~ E ~~
O u~ --, ~ O O o o C~ ) U U U
~ ~ n r L
C~ ^ ~' co ~ co ~ U U U ,-~-- ~ Z Z Z Z ~' ~; (-~ C ~: 'C ''-' O O O O "' Q) OJ . ~: m .~c u u~
H ~ E E
t~1 Z H H H H H H
~q ;,.
~l2 15~9L88 r ~' '.',''.,'.,'','','',',''.'','','.'',',"',".,',,''''',''''.,'.,','."'".. ''''','.'' ~ ''' ' --.......... ,..... .......
,,,,,,,,,,,,,,,,,,,,,.,, ,,,,,,,, ,, .. ,.. ,.,.,.. ,. ,,,,,,.,,,,, ,,:,:, EXAMPLE X
This example will illustrate the gas sealing capability of nitrile r~bber-containing gaskets of the present invention in comparison to sealing capabilities which are typically demonstrated by common cork-rubber gasket compositions. The gas leakage test is conducted using an electromechanical air-leakage tester according to procedures which are known in the art. The results also illustrate that if gas sealing is a desirable ~--gasket feature, pretreatment of the rice hulls with soybean oil (as illustrated in Example IXC), or other oil, may be advisable.
:
Flange Leakage -Pressure Rate -15 Sample (PSI) (PSI/Min.) . --.
Cork-rubber 200 1.00 --500 0.01 --IA 230 0.34 -350 0.05 E
IIA 230 0.25 ~--350 0.01 ~
.
IXC 230 0.09 --350 0.005 460 0.001 .
Our invention is not restricted solely to the -descriptions and illustrations provided above, but encompasses all modification envisaged by the following claims. :-....
....
. .,--.
, .. ................ .....................................................................
........... ,.. ,,. ;
, ., .. . , ., . .. . .. .......................... ...... ............ , ........ . .. ;
,," ,........ . .. .......... ............................
.
Claims (63)
1. A cured gasket composition obtained from a mixture comprising by weight 100 parts of a rubber binder;
from about 5 to about 1,000 parts of pulverized rice hulls; and from about 1 to about 200 parts of a polyester derived from at least one monomeric diol and at least one monomeric diacid or acid derivative, said polyester being at least partially crystalline under ambient conditions and having a Tg of from about -50° to about +80°C. and a weight average molecular weight of from about 1,000 to about 500,000.
from about 5 to about 1,000 parts of pulverized rice hulls; and from about 1 to about 200 parts of a polyester derived from at least one monomeric diol and at least one monomeric diacid or acid derivative, said polyester being at least partially crystalline under ambient conditions and having a Tg of from about -50° to about +80°C. and a weight average molecular weight of from about 1,000 to about 500,000.
2. The invention as set forth in claim 1 hereof wherein said rice hulls are comprised substan-tially of particles which are smaller than about 30 mesh (U.S. Standard).
3. The invention as set forth in claim 2 hereof wherein said particles are smaller than about 30 mesh.
4. The invention as set forth in claim 1 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
5. The invention as set forth in claim 4 hereof wherein said molecular weight is from about 2,000 to about 50,000.
6. The invention as set forth in claim 2 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
7. The invention as set forth in claim 6 hereof wherein said molecular weight is from about 2,000 to about 50,000.
8. The invention as set forth in claim 3 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
9. The invention as set forth in claim 8 hereof wherein said molecular weight is from about 2,000 to about 50,000.
10. The invention as set forth in claim 6 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
11. The invention as set forth in claim 7 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
12. The invention as set forth in claim 8 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
13. The invention as set forth in claim 9 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
14. The invention as set forth in claim 10 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
15. The invention as set forth in claim 11 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
16. The invention as set forth in claim 12 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
17. The invention as set forth in claim 13 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
18. The invention as set forth in claim 14 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
19. The invention as set forth in claim 15 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
20. The invention as set forth in claim 16 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
21. The invention as set forth in claim 17 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
22. A cured gasket composition obtained from a mixture comprising by weight 100 parts of a rubber binder;
from about 5 to about 1,000 parts of pulverized rice hulls; and from about 1 to about 200 parts of a crystallizable polyester derived from at least one monomeric diol and at least one monomeric diacid or acid derivative, said polyester having a weight average molecular weight of from about 1,000 to about 500,000 and having a Tg of from about -50 to about +80° C, said binder and said polyester comprising a polymer blend which exhibits Tg's attributable to the polyester and to the binder, said polyester comprising domains in which said polyester is at least partially crystalline under ambient conditions, but which can assume a substantially non-crystalline state in the operating environment of the gasket.
from about 5 to about 1,000 parts of pulverized rice hulls; and from about 1 to about 200 parts of a crystallizable polyester derived from at least one monomeric diol and at least one monomeric diacid or acid derivative, said polyester having a weight average molecular weight of from about 1,000 to about 500,000 and having a Tg of from about -50 to about +80° C, said binder and said polyester comprising a polymer blend which exhibits Tg's attributable to the polyester and to the binder, said polyester comprising domains in which said polyester is at least partially crystalline under ambient conditions, but which can assume a substantially non-crystalline state in the operating environment of the gasket.
23. The invention as set forth in claim 22 hereof wherein said rice hulls are comprised substantially of particles which are smaller than about 30 mesh (U.S. Standard).
24. The invention as set forth in claim 23 hereof wherein said particles are smaller than about 80 mesh.
25. The invention as set forth in claim 22 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
26. The invention as set forth in claim 25 hereof wherein said molecular weight is from about 2,000 to about 50,000.
27. The invention as set forth in claim 23 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
28. The invention as set forth in claim 27 hereof wherein said molecular weight is from about 2,000 to about 50,000.
29. The invention as set forth in claim 28 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
30. The invention as set forth in claim 29 hereof wherein said molecular weight is from about 2,000 to about 50,000.
31. The invention as set forth in claim 27 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
32. The invention as set forth in claim 28 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
33. The invention as set forth in claim 29 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
34. The invention as set forth in claim 30 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
35. The invention as set forth in claim 31 hereof wherein the Tg of said polyester is from about -20 to about +35°C.
36. The invention as set forth in claim 32 hereof wherein the Tg of said polyester is from about -20 to about +35°C.
37. The invention as set forth in claim 33 hereof wherein the Tg of said polyester is from about -20 to about +35°C.
38. The invention as set forth in claim 34 hereof wherein the Tg of said polyester is from about -20 to about +35°C.
39. The invention as set forth in claim 35 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
40. The invention as set forth in claim 36 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
41. The invention as set forth in claim 37 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
42. The invention as set forth in claim 38 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
43. A process for forming a gasket material, said process comprising the steps of preparing a composition comprising by weight (a) 100 parts of a rubber binder;
(b) from about 5 to about 1,000 parts of pulverized rice hulls; and (c) from about 1 to about 200 parts of a polyester derived from at least one monomeric diol and at least one monomeric diacid or acid derivative, said polyester being at least partially crystalline under ambient conditions and having a Tg of from about -50 to about +80°C. and a weight average molecular weight of from about 1,000 to about 500,000;
forming said composition into a desired configuration, and curing said formed composition.
(b) from about 5 to about 1,000 parts of pulverized rice hulls; and (c) from about 1 to about 200 parts of a polyester derived from at least one monomeric diol and at least one monomeric diacid or acid derivative, said polyester being at least partially crystalline under ambient conditions and having a Tg of from about -50 to about +80°C. and a weight average molecular weight of from about 1,000 to about 500,000;
forming said composition into a desired configuration, and curing said formed composition.
44. The invention as set forth in claim 43 hereof wherein said rice hulls are comprised substantially of particles which are smaller than about 30 mesh (U.S. Standard).
45. The invention as set forth in claim 44 hereof wherein said particles are smaller than about 80 mesh.
46. The invention as set forth in claim 43 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
47. The invention as set forth in claim 46 hereof wherein said molecular weight is from about 2,000 to about 50,000.
48. The invention as set forth in claim 44 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
49. The invention as set forth in claim 48 hereof wherein said molecular weight is from about 2,000 to about 50,000.
50. The invention as set forth in claim 45 hereof wherein said polyester has a molecular weight of from about 2,000 to about 300,000.
51. The invention as set forth in claim 50 hereof wherein said molecular weight is from about 2,000 to about 50,000.
52. The invention as set forth in claim 48 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
53. The invention as set forth in claim 49 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
54. The invention as set forth in claim 50 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
55. The invention as set forth in claim 51 hereof wherein, for every 100 parts of rubber binder, said mixture comprises from about 50 to about 800 parts of rice hulls and from about 10 to about 150 parts of polyester.
56. The invention as set forth in claim 52 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
57. The invention as set forth in claim 53 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
58. The invention as set forth in claim 54 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
59. The invention as set forth in claim 55 hereof wherein said polyester has a Tg of from about -20 to about +35°C.
60. The invention as set forth in claim 56 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neo-prene rubbers, EPDM rubbers, and combinations thereof.
61. The invention as set forth in claim 57 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
62. The invention as set forth in claim 58 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
63. The invention as set forth in claim 59 hereof wherein said rubber binder is selected from the group consisting of nitrile rubbers, SBR rubbers, neoprene rubbers, EPDM rubbers, and combinations thereof.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US552,622 | 1983-11-17 | ||
| US06/552,622 US4496674A (en) | 1983-11-17 | 1983-11-17 | Gasket materials comprising polyester and rice hulls |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1215488A true CA1215488A (en) | 1986-12-16 |
Family
ID=24206097
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000461232A Expired CA1215488A (en) | 1983-11-17 | 1984-08-17 | Gasket materials |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US4496674A (en) |
| JP (1) | JPS60124641A (en) |
| AU (1) | AU569906B2 (en) |
| BE (1) | BE901061A (en) |
| CA (1) | CA1215488A (en) |
| DE (1) | DE3441059A1 (en) |
| DK (1) | DK164367C (en) |
| FR (1) | FR2555191B1 (en) |
| GB (1) | GB2149807B (en) |
| NL (1) | NL188292C (en) |
| NO (1) | NO161569C (en) |
| SE (1) | SE464412B (en) |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5354620A (en) * | 1986-08-26 | 1994-10-11 | General Electric Co. | Polymer mixture based on a polyalkylenephthalate ester |
| JPH0634840B2 (en) * | 1986-11-20 | 1994-05-11 | 住友ゴム工業株式会社 | Tennis ball |
| CA1318741C (en) * | 1987-02-17 | 1993-06-01 | Boyd Terence Keogh | Additive product and a process for its manufacture |
| DE4331995A1 (en) * | 1993-09-21 | 1995-03-23 | Huels Chemische Werke Ag | Process for the production of composite articles from polyesters and elastomers |
| DE19854238B4 (en) * | 1998-11-24 | 2009-07-09 | Granula Polymer Gmbh | Use of a composition for the production of molded parts |
| AUPP819899A0 (en) * | 1999-01-18 | 1999-02-11 | Contract Research & Development (M) Sdn. Bhd. | Conductive and flame retardant plastic fillers |
| DE19914162A1 (en) * | 1999-03-29 | 2000-10-05 | Degussa | Composite object made of polyester and silicone rubber |
| US20020081247A1 (en) * | 2000-12-26 | 2002-06-27 | Dodson Christopher E. | Apparatus and method for producing amorphous silica ash |
| US6617376B2 (en) * | 2001-03-30 | 2003-09-09 | Crane Plastics Company Llc | Flexible wood composition |
| US7431168B2 (en) * | 2001-12-21 | 2008-10-07 | Rexam Medical Packaging Inc. | Closure for a retort processed container having a peelable seal |
| US7168581B2 (en) * | 2001-12-21 | 2007-01-30 | Rexam Medical Packaging Inc. | Closure for a retort processed container having a peelable seal |
| US7644902B1 (en) | 2003-05-31 | 2010-01-12 | Rexam Medical Packaging Inc. | Apparatus for producing a retort thermal processed container with a peelable seal |
| US7798359B1 (en) | 2004-08-17 | 2010-09-21 | Momar Industries LLC | Heat-sealed, peelable lidding membrane for retort packaging |
| US7780024B1 (en) | 2005-07-14 | 2010-08-24 | Rexam Closures And Containers Inc. | Self peel flick-it seal for an opening in a container neck |
| US8100277B1 (en) | 2005-07-14 | 2012-01-24 | Rexam Closures And Containers Inc. | Peelable seal for an opening in a container neck |
| US8251236B1 (en) | 2007-11-02 | 2012-08-28 | Berry Plastics Corporation | Closure with lifting mechanism |
| US20100024337A1 (en) * | 2008-08-04 | 2010-02-04 | Eco*Centric, LLC | Materials, Methods and Compositions for a Composite Building Material |
| CN108676213A (en) * | 2018-05-21 | 2018-10-19 | 芜湖瑞德机械科技有限公司 | Heat resistanceheat resistant collapsed seal circle and preparation method thereof |
| CN108707260A (en) * | 2018-05-21 | 2018-10-26 | 芜湖瑞德机械科技有限公司 | Improved composition and preparation method thereof for heat resistanceheat resistant collapsed seal circle |
| CN108690235A (en) * | 2018-05-29 | 2018-10-23 | 芜湖瑞德机械科技有限公司 | A kind of corrosion-resistant sealing ring and preparation method thereof |
| CN108822362A (en) * | 2018-05-29 | 2018-11-16 | 芜湖瑞德机械科技有限公司 | Corrosion-resistant sealing ring and preparation method thereof |
| CN109467756A (en) * | 2018-12-06 | 2019-03-15 | 安徽荣达阀门有限公司 | A kind of infiltration pressure piping gasket seal |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3388083A (en) * | 1964-06-01 | 1968-06-11 | Federal Mogul Corp | Novel rubber/fiber compositions and process for preparing same |
| CH459093A (en) * | 1966-06-20 | 1968-06-30 | Sulzer Ag | Loom |
| US3554941A (en) * | 1969-03-21 | 1971-01-12 | Concrete Dev Corp | Building material made of a mixture of polyester resin and rice hulls |
| US3932319A (en) * | 1972-07-28 | 1976-01-13 | Union Carbide Corporation | Blends of biodegradable thermoplastic dialkanoyl polymer, a naturally occurring biodegradable product, a plastic additive and a filler |
| US3951907A (en) * | 1972-07-28 | 1976-04-20 | The Regents Of The University Of California | Elastomeric and plastomeric materials containing amorphous carbonaceous silica |
| US4367316A (en) * | 1975-11-27 | 1983-01-04 | Toray Industries, Inc. | Vulcanized elastomeric molded article |
| NL184903C (en) * | 1976-06-11 | 1989-12-01 | Monsanto Co | PROCESS FOR PREPARING AN ELASTOPLASTIC MATERIAL, CONTAINING A THERMOPLASTIC, LINEAR, CRYSTALLINE POLYESTER AND A CROSSED RUBBER. |
| GR66059B (en) * | 1977-01-28 | 1981-01-14 | Continental Group | |
| DE2823872A1 (en) * | 1977-06-20 | 1979-01-04 | Teresio Signoretto | RUBBER COMPOSITION, IN PARTICULAR FOR THE PRODUCTION OF PANELS |
| JPS6011949B2 (en) * | 1978-09-20 | 1985-03-29 | 孝 安宅 | Method for modifying synthetic polymer compounds |
| US4287324A (en) * | 1980-05-12 | 1981-09-01 | Monsanto Company | Compositions of epichlorohydrin rubber and polyester |
| US4379190A (en) * | 1981-04-06 | 1983-04-05 | E. I. Du Pont De Nemours And Company | Filled thermoplastic compositions based on mixtures of ethylene interpolymers |
| US4403007A (en) * | 1980-08-11 | 1983-09-06 | E. I. Du Pont De Nemours & Co. | Filled thermoplastic compositions based on ethylene interpolymers and polyester, polyether and polyether ester plasticizers |
| US4327199A (en) * | 1981-01-19 | 1982-04-27 | Monsanto Company | Thermoplastic crystalline polyester modified acrylic copolymer rubber |
| AU552135B2 (en) * | 1981-12-09 | 1986-05-22 | Payen International Ltd. | Silicone resin impregnated paper gasket |
| US4559688A (en) * | 1983-10-24 | 1985-12-24 | General Motors Corporation | Bonding EPDM gaskets to filled nylon heat exchanger parts |
-
1983
- 1983-11-17 US US06/552,622 patent/US4496674A/en not_active Expired - Fee Related
-
1984
- 1984-08-17 CA CA000461232A patent/CA1215488A/en not_active Expired
- 1984-08-20 AU AU32084/84A patent/AU569906B2/en not_active Ceased
- 1984-10-18 NO NO844165A patent/NO161569C/en unknown
- 1984-10-30 FR FR8416565A patent/FR2555191B1/en not_active Expired
- 1984-11-02 NL NLAANVRAGE8403329,A patent/NL188292C/en not_active IP Right Cessation
- 1984-11-09 DE DE19843441059 patent/DE3441059A1/en active Granted
- 1984-11-16 SE SE8405740A patent/SE464412B/en not_active IP Right Cessation
- 1984-11-16 GB GB08428967A patent/GB2149807B/en not_active Expired
- 1984-11-16 DK DK547984A patent/DK164367C/en not_active IP Right Cessation
- 1984-11-16 BE BE0/214007A patent/BE901061A/en not_active IP Right Cessation
- 1984-11-16 JP JP59240923A patent/JPS60124641A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| AU569906B2 (en) | 1988-02-25 |
| JPH0443948B2 (en) | 1992-07-20 |
| GB2149807A (en) | 1985-06-19 |
| DK547984A (en) | 1985-05-18 |
| DK547984D0 (en) | 1984-11-16 |
| GB8428967D0 (en) | 1984-12-27 |
| SE8405740D0 (en) | 1984-11-16 |
| NL188292C (en) | 1992-05-18 |
| SE464412B (en) | 1991-04-22 |
| DK164367B (en) | 1992-06-15 |
| GB2149807B (en) | 1987-11-18 |
| DE3441059C2 (en) | 1987-05-07 |
| NO161569C (en) | 1989-08-30 |
| FR2555191A1 (en) | 1985-05-24 |
| DK164367C (en) | 1992-11-30 |
| BE901061A (en) | 1985-03-15 |
| US4496674A (en) | 1985-01-29 |
| NO161569B (en) | 1989-05-22 |
| FR2555191B1 (en) | 1988-08-12 |
| NO844165L (en) | 1985-05-20 |
| JPS60124641A (en) | 1985-07-03 |
| NL8403329A (en) | 1985-06-17 |
| NL188292B (en) | 1991-12-16 |
| SE8405740L (en) | 1985-05-18 |
| DE3441059A1 (en) | 1985-05-30 |
| AU3208484A (en) | 1985-05-23 |
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