WO2013010326A1

WO2013010326A1 - Ready to use gasket

Info

Publication number: WO2013010326A1
Application number: PCT/CN2011/077380
Authority: WO
Inventors: Shabbir Attarwala; Viraj KADAM; Jagadeesh KOMPALA; Peter Wrobel; Gan YOKEAI; Hao Yin; Gregg ROSSIER; Pradhyumna INGLE
Original assignee: Henkel Ag & Co. Kgaa
Priority date: 2011-07-20
Filing date: 2011-07-20
Publication date: 2013-01-24
Also published as: WO2013010497A1; TW201309944A

Abstract

Disclosed is a gasket, comprising a carrier, an adhesive layer on each side of the carrier, and a releasing layer on the top of each adhesive layer. This gasket is ready to use. It combines advantages of solid gaskets and liquid gaskets and can be handled easily at assembly lines.

Description

Ready to Use Gasket

FIELD OF THE INVENTION

This invention relates to the field of gasket, particularly directs to a ready to use gasket.

BACKGROUND OF THE INVENTION

A gasket is a mechanical seal that fills the space between two mating surfaces, especially between two flanges, generally to prevent leakage from or into the joined objects while under compression. Most major manufacturing sectors, including the automotive, aerospace, electronics, appliance, and military industries, employ gaskets in their production methods. Gaskets create a pressure-tight seam between multiple stationary components, relying on a compression seal to prevent unwanted gas or liquid emissions.

There are numerous types of gaskets, among which solid gaskets and form-in-place gaskets are two of the most common varieties of gasket.

Conventional gaskets are formed of solid materials, typically cork, cardboard, fabric, graphite, metals etc. We call them solid gaskets (or solid material gaskets).

Solid gaskets are easy to handle and user friendly, but they can not be used to achieve 100% sealing, because solid materials do not go into micro imperfections between two flange surfaces.

Then there came the idea of using form-in-place gaskets (or FIP gaskets), which are liquids or sealants that cure after the parts are assembled. Since liquids or sealants go into micro imperfections between surfaces, FIP gaskets can achieve 100% sealing. But FIP gaskets require dispensing equipments, usually along with robotic systems, which means more investment. Moreover, handling sticky liquids or sealants at assembly lines is troublesome.

For applications where flange widths are small, dispensing of FIPG (e.g.

Silicone) is an issue and even risky as liquid materials may get entrapped in oil holes etc (such as in small engines).

There have been many efforts and reports on improving gaskets and gaskets materials for various applications.

JP 199514121 OA discloses a gasket material, which is used for oil seal and comprises: a steel sheet coated with heat-resistant adhesive; compound layers on both sides of the steel sheet containing base material fibers, a rubber material and an inorganic filler; and silicone layer on top of the compound layers. The compound layers contain base material fibers, inorganic filler and a rubber material having oil swelling properties.

JP8109368 provides a composite gasket suitable for flanges of fluid pipes for stream, an oil etc. This composition gasket is obtained by laminating a sheet substrate comprising >5wt% polytetrafluoroethylene resin and >30wt% inorganic filler, as necessary, through an organic adhesive to one or both sides of a woven fabric.

US7771641 B2 describes a lid component part of an internal combustion engine with integrated elastic seal. The component part exhibits a circumferential flange area for he arranging of the integrated seal and is based on a plastic-material, while the seal essentially comprises an organic elastomer material. The component part and the seal are chemically bonded with one another. The seal is applied by injection molding onto the component part.

DE4332346A discloses that a flat gasket (seal, packing) made of graphite material, in particular a cylinder head gasket or an exhaust flange gasket for internal combustion engines, is provided on one or both sides with an epoxy resin coating so that it can be mass-produced under operating conditions with good resistance to the media which it seals off and to the operating temperature, with good adhesive properties to applied elastomeric supports or coatings, and with good properties of counter-acting adhesive bonding at the sealing faces, all at the same time and without extensive safety equipment.

DE3707598 Al provides a soft-material flat gasket material comprising a laminate with at least one graphite sheet or graphite film and, if appropriate, a reinforcing metal plate contains additives of a binder of preferably 1-15% by weight of thermoset synthetic resins, elastomers and/or inorganic binders and a substance conteracting the adhesion, such as, preferably, 0.5-10% by weight of metal soaps, waxes and/or preferably micronised polytetrafluoroethylene powder. The sealing material is not adhesive to the sealing surfaces, despite the reduced binder content it has good strength so that it can be punched and handled without chipping and, because of the low binder content, possesses the sealing behavior, the heat resistance and the deformation properties of an additive-free graphite gasket, so that it can advantageously be used as a cylinder head gasket, as exhaust flange gasket or as auxiliary gasket in internal combustion engines.

JP2000230639A describes a duct flange gasket and an apparatus for preparing the same. The duct flange gasket comprises a core of tape-like rock wool, which is enclosed by polyester nonwoven fabric. Both ends of the polyester nonwoven fabric are bended in the butt state. An adhesive double coated tape having a release paper is adhered to the nonwoven fabric so as to cover the butt surfaces of the nonwoven fabric.

Despite all these prior arts, there is still a need for ready to use gaskets, which are user friendly and also has excellent sealing performances.

The present invention provides a novel gasket, which combines advantages of solid gaskets and liquid gaskets and can be handled easily at assembly lines.

SUMMARY OF THE INVENTION

This invention is directed to a gasket, comprising a carrier, an adhesive layer on each side of the carrier, and a releasing layer on the top of each adhesive layer.

In one embodiment, the releasing layers of the gasket are striped off upon use.

In one embodiment, the adhesive layers of the gasket are cured upon the assembly of the gasket.

In one embodiment, the adhesive composition is tailored so that the adhesive force between the adhesive layer and the carrier is larger than that between the adhesive layer and the releasing layer.

Advantages of the inventive gasket include:

Cost saving— the inventive gasket could save as high as 80% cost compared with some traditional gaskets.

Well prepared at any moment for use— since the gasket has releasing layers as its outside layers and there is no need to coat adhesive first, it is convenient for use.

Fill in surface imperfections in sealing parts— compared with gaskets without grease/oil/shellac, the adhesives of the inventive gasket could fill in all imperfections in surfaces of sealing parts and hence reduce leakages from joints. When being used in engines, the inventive gasket could increase efficiencies of engines.

Various other features, aspects, and advantages of the present invention will become more apparent with reference to the following description, examples, and appended claims.

DESCRIPTION OF DRAWINGS

Fig. 1 illustrates the use of the inventive gasket between flanges.

Fig. 2 illustratively shows the five-layer structure of the inventive gasket. DETAILS OF THE INVENTION

All publications, patent applications, patents and other references mentioned herein, if not otherwise indicated, are explicitly incorporated by reference herein in their entirety for all purposes as if fully set forth.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, the present specification, including definitions, will control.

Unless stated otherwise, all percentages, parts, ratios, etc., are by weight.

When an amount, concentration, or other value or parameter is given as either a range, preferred range or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. For example, when a range of "1 to 5" is recited, the recited range should be construed as including ranges "1 to 4", "1 to 3", " 1-2", "1-2 & 4-5", " 1-3 & 5", and the like. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range.

When the term "about" is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

Further, unless expressly stated to the contrary, "or" refers to an inclusive "or" and not to an exclusive "or". For example, a condition A "or" B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).

Also, the indefinite articles "a" and "an" preceding an element or component of the invention are intended to be nonrestrictive regarding the number of instances (i.e. occurrences) of the element or component. Therefore, "a" or "an" should be read to include one or at least one, and the singular word form of the element or component also includes the plural unless the number is obviously meant to be singular.

The materials, methods, and examples herein are illustrative only and, except as specifically stated, are not intended to be limiting. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

The invention is described in detail hereinafter. Gasket

In describing and/or claiming this invention, the term "gasket" refers to a mechanical seal that fills the space between two mating surfaces, such as the facing surfaces of two flanges.

A gasket is generally used to prevent leakage from or into the joined objects while under compression. Gaskets allow "less-than-perfect" mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced by cutting from sheet materials, such as gasket paper, rubber, silicone, metal, cork, felt, neoprene, nitrile rubber, fiberglass, or a plastic polymer (such as polychlorotrifluoroethylene). Gaskets for specific applications may contain asbestos. It is usually desirable that the gasket be made from a material that is to some degree yielding such that it is able to deform and tightly fills the space it is designed for, including any slight irregularities.

An important application of gaskets is being used between flanges as flange gaskets in different mechanical equipment such as engines etc. Examples of flange gaskets include oil cooler gasket, timing gear case gasket, timing gear case to timing gear cover gasket, water pump gasket, air conditioner sleeve gasket, upper water cooling gasket and gasket for fuel injection pump on timing gear housing.

As abovementioned, solid gaskets and form-in-place gaskets are two of the most common varieties of gasket. Solid gaskets are easy to handle, but can not achieve 100% sealing. Form-in-place gaskets (or FIP gaskets) can achieve 100% sealing, but require dispensing equipments and are difficult to handle at assembly lines.

This invention provides a ready to use gasket, which has a five-layer structure, comprising a carrier, an adhesive layer on each side of the carrier, and a releasing layer on the top of each adhesive layer. Fig 2 illustratively shows the five-layer structure of this ready to use gasket, wherein layer 1 is carrier, layer 2 are adhesive layers, and layer 3 are releasing layers.

The term "ready to use" here means that the gasket can be directly used in assembly processes, without the need for applying oil, grease, adhesives or sealants.

Carrier

According to the present invention, a carrier is provided in the middle of the five-layer structure. The strength of a carrier determines the final strength of the gasket.

In principle, all materials that are used in preparing conventional gaskets can be used to produce the carriers of the present invention. Suitable materials include paper, cardboard, rubber-cellulose, rubber metallic, cork rubber, rubber fiber, microfiber and so on.

In one embodiment of the present invention, the carrier is a prefabricated gasket. A wide range of prefabricated gaskets are applicable, including cork gaskets, cardboard gaskets, fabric gaskets, graphite gaskets, metal gaskets etc.

The shapes of the carriers should be tailored to meet the shapes of the gaps between flanges and joints. And materials of the carriers should be stable under assembly conditions and working conditions, such as high pressure and high temperature.

The adhesives shall not penetrate into the carrier in avoid of damage to carrier's mechanical performances. Also materials of the carriers should be inert to components of the adhesive layers, to avoid undesirable by-reactions that may deteriorate the strength of the carriers.

There are cases where reactions between carrier materials and adhesives are desired, for example, for better bonding between carriers and adhesive layers.

Adhesive layers

Adhesive layers are provided on both sides of the carrier. The adhesive layers allow the gasket to be positioned on a gasket surface and holds it in place while mating gasket surfaces are aligned and positioned. Preferably, it holds aggressively yet still allows for repositioning of the gasket.

Adhesive layers play many roles in the present invention.

Firstly, they help keep the gasket in place during assembly processes. At present, many manufacturers, such as car manufacturers are using oil, grease or shellac for positioning and placing solid gaskets in place. This is very messy operation.

Secondly, the adhesive layers improve the sealing between flanges and joints, especially when they are cured. As fluid or semi-fluid materials, the adhesive layers can fill in surface imperfections in sealing parts, whereby achieve sealing effects that are comparable to those achieved by using FIP gaskets.

Moreover, compared with metal parts joined by gaskets, the adhesive layers in the inventive gaskets, even after being cured, are more flexible and has high thermal expansion coefficients and hence low heat distortion under high temperature. This releases the stress caused by heat distortion under high temperature, such as in an engine.

Furthermore, since the adhesive layers could accommodate differential thermal expansions of flanges, they help maintain the structural integrity of an apparatus, e.g. engines, and could prevent bolts from loosening. Preferably, the cured adhesive layers also have high permeability resistance to fuel gas and therefore it could prevent the leakage of fuel gas to reduce the emissions.

The adhesive layers of the inventive gasket may comprise reactive resins for the purpose of improving sealing performance and reducing emissions. Preferably, the reactive resins do not cure before being placed at assembly position and cure when being subjected to assembly conditions, so as to form in place gaskets, which give perfect sealing and benefits of solid gasket.

Preferably, the adhesive layers are supplied as a wax-like semi-solid, particularly for applications where a liquid adhesive layers may be too fluid to hold aggressively or be too difficult to handle. Gaskets with semi-solid adhesive layers store easily and allow for direct contact to metal surfaces during assembly.

A wide range of materials can be used in the adhesive layers of the present invention, including anaerobic adhesives, pressure sensitive adhesives and silicones.

As components for the adhesive layers, the following reactive materials have shown advantageous performances:

flange Sealants, such as Loctite®515, Loctite®518, Loctite®534, Loctite®620, Loctite®2440, made by Henkel Corporation;

aqueous sodium silicate solution;

aqueous boric acid solution;

aqueous epoxy and sodium silicate /boric acid mixture;

aqueous acrylate with sodium silicate/ boric acid; and

benzoxazine resins.

In a preferable embodiment, the adhesive layers are formed of anaerobic adhesives.

It should be noted that anaerobic adhesives are not recommended for use in pure oxygen and/or oxygen rich systems and should not be selected as a sealant for chlorine or other strong oxidizing materials.

In a further preferable embodiment, the adhesive layers are formed of an adhesive composition comprising pressure sensitive adhesives.

In a further preferable embodiment, the adhesive layers are formed of an adhesive composition comprising silicones.

Preferably, the adhesive force between the adhesive layer and the carrier should be larger than that between the adhesive layer and the releasing layer, so as to decrease the transfer of adhesives from carriers to the releasing layer as much as possible. The adhesive layers of the present invention may further contain small amounts of optional additives commonly used and well known in the art. Examples of additives include without limitation filler components such as those comprising one or more of silica, clays, talc etc; a wetting agent component; stabiliser components.

These additive(s) may be present in the adhesive layers in appropriate quantities, so long as they do not detract from the basic and novel characteristics of the adhesive layers and do not significantly adversely affect the performance of the inventive gaskets. Releasing layers

Releasing layers are applied on top of the adhesive layers to protect the adhesive layers from being scratched and keep the composition of the adhesive layers.

Releasing layers may be striped off upon assembly to expose the adhesive layers. Typically, releasing layers may be striped off at assembly sites, but there are cases where it is desirable to remove the releasing layers before the ready to use gaskets are transferred to assembly sites, in order to keep the assembly sites orderly and clean and also for faster assembly.

A release layer may be formed of various materials including paper, plastics, fabric including unwoven fabrics and so on.

Sometimes release layers are provided with coatings to further decrease the adhesive force between the adhesive layer and the releasing layer. For this purpose, the coating may contain grease, silicone or silicone oil.

Assembly of the gasket

The assembly of the inventive gaskets can be operated conveniently. Workers at assembly sites may simply peel off the releasing layers and put the remaining part of the gasket (i.e., a carrier coated with adhesive layers) on one flange and assemble another flange with a fastener.

After being placed on right places, the adhesive layers of the gaskets may be cured under anaerobic condition, under pressure, or upon heating. Normally, it cost several hours to mostly finish curing, but it may need several days to completely cure.

Gasket with adhesive should apply to the entire flange to seal out moisture and contaminants. Gasket is typically applied to the flange area of the light panel before the panel is installed on the heavy panel. Tests

The inventive gaskets shall pass all necessary tests for solid gaskets and FIP gaskets.

There are three most important tests to guarantee the performance of the gasket. They are Lap Shear Test based on ISO 4587 standard, Chemical Resistance/solvent resistance Test and Sealing Capability Test based on STM 791.

For gaskets designed for engines, they should also pass 500 hours dyno Engine test. EXAMPLES

Gaskets according to the present invention were prepared and used in assembling flanges.

Example 1: preparing adhesive composition

The following chemicals were charged in a spin mixer and spun at 1500 min^"1 for 2 minutes:

Polyurethane methacrylate resin, 78g,

Polyglycol dimethacrylate, 18g,

1 -Acetyl-2-phenylhydrazine, 0.32g,

1,4-Naphthoquinone, 0.007g,

1,2-DIHYDROXYPROPANE, 4.3g,

a mixture of ethylenediaminetetraacetic(5%), water(44%),

l,2-dihydroxypropane(15%) and EDTA(37%), 0.71g;

and

Saccharin l .lg.

Subsequently, 0.55g modified urea was added in the mixer cup of the spin mixture and mixed at 1500 min-1 for 2 minutes, 4.3g cumene hydroperoxide was added in the mixer cup and mixed at 1500 min-1 for 2 minutes, then 16g Disparlon 6200 was added in the mixer cup and mixed at 1500 min-1 for 4 minutes. Disparlon 6200 is a kind of long chain hydrophobic wax, it was obtained from Henkel Puerto Rico, Inc.

The resulted mixture was heated at 60°C for 2 hours. Example 2: preparing ready to use gasket

A carrier material of desired shape (gasket shape) was cut out of a non-woven paper. The adhesive composition prepared in Example 1 was applied on one side of the carrier material to a thickness of about 0.1mm. Once the adhesive was applied on the carrier material, a PET release liner was carefully mounted on the adhesive layer. Then, the carrier material was turned over, and the adhesive composition prepared in Example 1 was applied on the other side of the carrier material and subsequently covered by a release liner. As a result, a ready to use gasket was obtained.

Example 3: using the ready to use gasket in assembling flanges

Before applying the ready to use gasket prepared in Example 2 on a metal surface of a flange, the metal surface to be in contact with the gasket was cleaned. Surface contaminants were removed, and surface treatments were conducted. Once the surface was dry, the release liner of the ready to use gasket was removed, and the gasket was mounted on the flange, with its exposed adhesive layer facing and in contact with the metal surface to be bonded. Afterward, the other release liner of the ready to use gasket was removed. The above flange with a ready to use gasket was installed on a mating flange, with the ready to use gasket sandwiched between the mating surfaces of two flanges.

While the invention has been illustrated and described in typical embodiments, it is not intended to be limited to the details shown, since various modifications and substitutions are possible without departing from the spirit of the present invention. As such, modifications and equivalents of the invention herein disclosed may occur to persons skilled in the art using no more than routine experimentation, and all such modifications and equivalents are believed to be within the spirit and scope of the invention as defined by the following claims.

Claims

CLAIMS What is claimed is:

1. A gasket, comprising

a carrier,

an adhesive layer on each side of the carrier, and

a releasing layer on the top of each adhesive layer.

2. The gasket of claim 1, wherein the releasing layers are striped off upon use.

3. The gasket of claim 1 or 2, wherein the adhesive layers are cured upon the assembly of the gasket.

4. The gasket as claimed in any of claims 1-3, wherein the adhesive layers are formed of an anaerobic adhesive composition.

5. The gasket as claimed in any of claims 1-3, wherein the adhesive layers are formed of a pressure sensitive adhesive composition.

6. The gasket as claimed in any of claims 1-3, wherein the adhesive layers are formed of silicone.

7. The gasket as claimed in any of claims 1-6, wherein the carrier is made of cork, paper, cardboard, fabric, rubber-cellulose, rubber metallic, rubber fiber, microfiber, graphite, metals or combination thereof.

8. The gasket as claimed in any of claims 1-6, wherein the carrier is a prefabricated gasket.