EP0782676A1

EP0782676A1 - Sealing member

Info

Publication number: EP0782676A1
Application number: EP95931294A
Authority: EP
Inventors: Michael John Percy; Iain Laird; Paul Andrew Bradley; William Joseph Egenton; Jacob Abboud
Original assignee: Raychem Ltd
Current assignee: Raychem Ltd
Priority date: 1994-09-21
Filing date: 1995-09-11
Publication date: 1997-07-09
Also published as: JPH10505894A; AU3478595A; KR970706461A; CN1164272A; CN1044152C; BR9508856A; MX9702093A; CA2200593A1; WO1996009483A1

Abstract

Tubular layer of sealant (32) (preferably gel) on flexible (preferably tubular) carrier (30) provides advantageous sealing member, which can conveniently be compressed, e.g. in a tongue-and-groove joint (34, 36), to provide a sealed joint in items such as cable splice enclosures, car head lamp housings, gas meter casings, and domestic appliances. Styrene-alkylene or alkylmethacrylate-alkylene block copolymer gels coated (preferably co-extruded) on thermoplastic elastomer carriers are described. Gasket rings cut from such tubular articles, and provision of projecting fixing lugs for anchoring the articles to an object which is to carry them in use are also described.

Description

SEALING MEMBER

This invention relates to a sealing member which may be used for forming a seal between two surfaces, for example in a protective housing to protect the contents of the housing from contamination, or within a domestic appliance or other device to prevent fluids from penetrating into parts where they would cause nuisance or damage.

Many kinds of seal are known in which various materials may be placed between the surfaces to be sealed, for example greases and mastics, strips of foamed polymeric material, rubber gaskets, and gel materials which may be used in bulk, for example as described in WO-A-93/17477 (B219), or may be carried on a gasket-like structure, to be compressed between two surfaces for example as disclosed in WO-A-94/05935 (B236).

The present invention relates to a new form of sealing member having considerable advantages over known kinds for various purposes.

The invention accordingly provides a sealing member comprising a tubular body of sealant material carried by an internal (to the tubular body) flexible (preferably resiliently-flexible) gas-containing carrier, the sealant material having a cone penetration within the range from 80 to 400 (10"* mm) and an ultimate elongation of at least 100%, preferably at least 200%, more preferably at least 500%.

Preferred sealant materials are gels, as hereinafter described, which may provide a degree of encapsulation and corrosion protection in addition to the sealing function.

The shape of the carrier is not critical, square or hexagonal profiles, for example, being feasible, and the same applies to the tubular profile of the sealant.

Preferably, the carrier is also tubular, for example a rounded, more preferably a substantially circular tube, which is also the preferred form for the tubular body of sealant. However, the carrier may also be a solid or tubular body of foamed polymeric material, preferably having open foam cells, or such a foam might be present on the outer surface of a solid carrier, preferably a solid-walled tube carrier, and/or within the bore of a solid- walled tube.

It will be understood that the provision of a tubular body of sealant material on a carrier as specified can enable a relatively small volume of sealant to seal a relatively large space, which is advantageous when expensive sealants are required. The specified use of a gas-containing flexible carrier, preferably a flexible tube and/or foam, has the further advantage that the sealant can be deformed by compression, to make good contact with the surfaces to be sealed, using considerably less force to deform the carrier (thus compressing or displacing the gas) than would be required to displace a solid body of sealant, or sealant on a solid carrier, in a confined space. The preferred use of a resiliently-flexible carrier has the additional advantage that the resilient recovery force of the deformed carrier can be used to maintain the sealant under compression against the surfaces to be sealed, which is especially desirable when the sealant is a gel as hereinafter described. For some purposes however, adequate seals may be formed with very slight compression of, or possibly mere contact with, the tubular body of sealant.

The invention accordingly includes the sealing member when positioned on a first body, preferably in a channel formed in the first body, which is capable of receiving a portion of a second body to form a seal between the first body and the second body, preferably with compression of the sealing member. The channel in which the sealing member may be placed may be of any shape to match the shape of the sealing article. However, mathematical modelling indicates that desirable stress distributions may be achieved when the sealing member, preferably of the preferred rounded or substantially circular shape, is positioned in an angular channel, preferably a substantially rectangular channel, in the first body, thus preferably forming a seal by compression of the sealing member within a tongue- and-groove type connection between the first and second bodies.

The sealing members according to this invention may be especially useful, for example, in sealing joints in housings for electrical or other apparatus, e.g. cable splice casings for telecommunications or other purposes, traffic sensor domes, gas meter casings, automotive lamp assemblies and mirror mountings, domestic appliances (e.g. condenser seals in tumble dryers, refrigerators), and in many other gasket or flange sealing arrangements. The sealing member may be cut to length, and may when required be joined together at its ends to form a closed loop, e.g. by means of adhesives or by sliding the ends of a tubular carrier over a short coupling rod.

The invention accordingly includes a method of forming a seal between a first body and a second body comprising placing a sealing member according to this invention in contact with a portion of the first body and bringing a portion of the second body into compressive contact with the sealing member so as to compress the sealing article between the first and second bodies. The invention also includes a housing component for electrical or other apparatus the housing component carrying a sealing member according to this invention and the sealing member being positioned on the housing component so as to be compressed and form a seal between the housing component and another body with which the housing component will be assembled in use. Preferably, the housing component will carry the sealing member in a channel arranged to receive a mating part of the said other body in use to form a sealed connection, preferably a tongue-and-groove type of connection. The invention also includes the housing component and sealing member when assembled together with the said other body to form the seal. Also included is a kit of parts comprising the housing component and the sealing member capable of being positioned thereon and assembled with the said other body as aforesaid. Such a kit may also include the said other body, preferably a second housing component, capable of assembly together with the said housing component to compress the said sealing member to form a seal between the said housing component and the said other body.

In preferred sealing members according to this invention, the sealant material has been applied in a molten state, and preferably under elevated pressure, to the carrier, preferably with at least a surface region of the carrier being or becoming molten or softened while in contact with the molten sealant material. Application of molten sealant, especially under pressure, tends to enhance the adhesion of the sealant to the carrier. The adhesion tends to be further enhanced by the preferred melting or softening of at least the surface of the carrier, since this will tend to form an mtermingled or enhanced-contact bondline region. Good adhesion is especially desirable when the preferred gel sealants are used, since the coherent strength of the gels will then tend to promote clean removal of the gels from the sealed surfaces on separating them to obtain re-entry to a sealed housing or other device, as is often required in practice. Thus, it is preferred that the adhesion strength of the sealant material to the carrier is greater than its adhesion strength to a body with which it is to be placed in sealing contact in use. Usually, it will be preferable for the cohesive strength of the gel to exceed its adhesion strength, at least to the carrier and body used in specific cases, and especially to itself, thus enabling the sealing member to separate cleanly from itself when a length is being removed from a coil or other compact storage arrangement of the sealing member.

Enhanced adhesion may be achieved when the carrier is an extruded article and the sealant material has been applied during or immediately after the extrusion of the carrier, preferably by co-extrusion with the carrier. However, it is also possible to extrude the sealant material onto a pre-formed carrier, for example using known kinds of apparatus used for extruding polymer insulation onto electrical wires. Good adhesion may still be obtained, for example by pre-heating the carrier and/or by selecting suitably compatible materials for the carrier and the sealant. Primers and/or bonding agents may also be used to enhance adhesion. Cooling of the extruded gel layer by feeding the extruded article through a water bath has been found surprisingly effective in producing satisfactory articles for subsequent end use.

The invention accordingly includes a method of forming a sealing member according to this invention, comprising applying a tubular layer of the said sealant material in a molten state to the said carrier and causing or allowing the applied sealant material to solidify. This method preferably involves extruding the carrier and applying the sealant material thereto during or immediately after the extrusion of the carrier, preferably by co-extrusion with the carrier, but may instead comprise extruding the sealant material onto a pre-formed carrier, preferably after warming the carrier surface. Suitable processing equipment and conditions will readily be selected by those familiar with such matters.

Compatible materials to achieve desirably high levels of adhesion may be selected by trial and error. Preferred materials for at least the outer surface region (preferably for the whole) of the carrier in some cases include materials composed of, or comprising as a majority component, ethylene/vinyl acetate copolymer containing less than 40%, preferably less than 20%, by weight of vinyl acetate, ethylene/alkyl (preferably methyl) aery late copolymer containing less than 40%, preferably less than 20%, by weight of alkylacrylate, or polyethylene, preferably low-density polyethylene. Alternatively, for example for the preferred resiliently- flexible carriers, elastomer materials, preferably thermoplastic elastomer materials, especially olefinic elastomers, are desirable, examples of which include

very low density polyethylene (VLDPE) plastomer, e.g. Dow Plastics' Engage CL8001 (Trade Mark), which is believed to be a polyolefin elastomer of ethylene with 25% octene co- monomer;

polyether/polyester block copolymer, e.g. DuPont's Hytrel (Trade Mark) softer, lower-melt-viscosity grades such as G4074;

polypropylene-based elastomer, e.g. DSM's Sarlink 3140 (Trade Mark), which is believed to be a polypropylene/EPDM blend having a Shore A hardness (5 seconds) of 42 (extruded) to 49 (injection moulded).

Especially good compatibility and adhesion between the carrier and the sealant may be achievable by making the carrier out of the same or closely related polymers as the preferred triblock gels, but without the gel-forming high content of extender liquid for the mid-block. Triblock copolymers of the kinds mentioned herein may be compounded with known fillers and other ingredients to form carrier materials which will tend to have useful affinity to the same or similar polymers forming the gel.

As previously mentioned, the sealant material is preferably a gel, more preferably a thermoplastic gel, although crosslinked or thermoset gels are not excluded. It is preferred that the gel has substantially elastic deformation up to an elongation of at least 100%; and that the gel has ultimate tensile strength (ASTM D412) less than 1 MPa, dynamic storage modulus less than 50 kPa, and substantially zero slump at temperatures up to 100°C, preferably up to 120°C.

In an especially preferred form of sealing member according to this invention the sealant material is a gel comprising

(i) a styrene-alkylene block copolymer, preferably a styrene- (hydrogenated alkylene)-styrene triblock copolymer, more preferably a styrene-(ethylene/propylene and/or ethylene/butylene)- styrene triblock copolymer having a weight average molecular weight Mw of at least 180,000, and

(ii) at least 300 (preferably at least 400, more preferably at least 500) parts by weight of extender liquid per 100 parts of the block copolymer, which liquid extends and softens the alkylene blocks of copolymer.

Preferred gels made from styrene-(ethylene/butylene)-styrene (SEBS) block copolymers, and test methods for defining and characterising gels are described in WO-A-8800603 (RK308) and WO-A-9005166 (RK403), the disclosures of which are incorporated herein by reference. The most preferred gels described in WO-A- 9323472 (RK469), the disclosure of which is incorporated herein by reference, are made from styrene-(ethylene/propylene)-styrene (SEPS) block copolymers, in which the ethylene/propylene mid-block may include some ethylene/butylene units. These preferred SEPS copolymers have weight average molecular weight Mw of at least 180,000, preferably at least 200,000, more preferably at least 220,000, and polystyrene content of 25-45 weight percent, preferably 28-40 weight percent, more preferably 29-36 weight percent, and are made with substantially or wholly non- aromatic extender liquid. The gels are preferably soft, high-temperature-slump- resistant, springy gel compositions, by which is meant liquid-extended polymer compositions having an ultimate elongation (measured by ASTM D412 modified as described below) greater than 100%, with substantially elastic deformation (i.e. substantially no hysteresis) to an elongation of at least 100%; ultimate tensile strength (ASTM D412) less than 1 MegaPascal; dynamic storage modulus (as hereinafter described) less than 5000 Pascals; and substantially zero slump at temperatures up to 100°C, preferably up to 120°C, more preferably up to 135°C, and especially up to 150°C.

The invention for some purposes may be more particularly concerned with such gel compositions comprising 4-30 weight % of the styrene-alkylene block copolymers based on the weight of the whole composition, especially those comprising from 4% to 20% by weight of the said copolymer and at least 500 parts by weight of extender liquid per 100 parts by weight of the gelling polymer, in which the said copolymer comprises more than 50%, preferably more than 75%, more preferably more than 90%, and especially more than 95%, by weight, or substantially all, of the total gelling polymer present. Various additives may be present, for example the tackifiers described in WO-A-9005166 or the polyphenylene oxide described in WO-A-8800603, or styrene-alkylene di-block copolymers, e.g. styrene-ethylene/propylene or styrene-ethylene/butylene diblock copolymers, for reducing the loss of extender liquid as described in WO-A-9305113 (RK451), the disclosure of which is incorporated herein by reference.

Specific embodiments and end uses of the invention will now be described by way of example, with reference to the accompanying drawings, wherein: -

Figure 1 shows a schematically in perspective a possible hexagonal sealant profile on a square carrier;

Figure 2 similarly shows a possible square sealant profile on a round tubular carrier having a foam coating on its outer surface;

Figure 3 shows schematically a tongue-and-groove joint containing the preferred round tubular sealing member of the present invention, in comparison with a round solid body of sealant in a similar joint;

Figure 4 similarly shows the preferred sealing member in comparison with a solid body of sealant in a simple overlap joint;

Figure 5 shows the preferred sealing member in a possible confined abutment compression arrangement; Figure 6 shows schematically in perspective a moulded plastics sleeve housing for enclosing telecommunications cable splices, the housing having a longitudinal tongue-and-groove edge closure;

Figure 7 shows a schematic end view of the tongue-and-groove closure of Figure 6 before and after closing with the preferred sealing member in the groove;

Figure 8 shows schematically in sectioned perspective a two-part housing with tongue-and-groove joint sealed by the preferred sealing member; and

Figure 9 shows schematically in cross-section a side elevation of an automotive headlamp housing incorporating the sealing member.

Referring to the drawings, Figure 1 shows a square carrier strip 11 of foamed polymer over which has been extruded a tubular coating of gel 12 having a hexagonal outer profile.

Figure 2 shows a carrier comprising an extruded hollow tube of ethylene/vinyl acetate (EVA) copolymer 20, having a substantially concentric outer layer of foamed polymer 22 (formed by known methods), over which has been formed a tubular layer of gel 24 having a square outer profile.

Figure 3A shows an end view of a preferred sealing member having a round tubular carrier 30 of extruded thermoplastic elastomer having a substantially concentric tubular layer of gel 32 co-extruded thereon, in a channel 34, which might in practice be formed in a main surface or an edge of a body to be sealed. Figure 3B shows an edge portion 36 of a second body introduced into the channel 34 to form a tongue-and-groove joint, thus easily compressing the hollow sealing member and causing the gel to seal the joint. The arrangement shown in Figure 3A could also be used to form a seal against a surface of a second body laid across the top of the channel 34 so as to compress the sealing member therein. The resilience of the preferred thermoplastic elastomer carrier tends to maintain the gel under compression against the sealing surfaces, thus compensating for thermal expansion and contraction to maintain the seal. For comparison, Figures 3C and 3D show a corresponding tongue-and- groove joint with a solid body 38 of sealant. In the absence of the gas incorporated in the carrier of the present invention, the solid sealant is substantially incompressible and therefore requires much higher forces to distort and/or displace it on formation of the joint. Relatively small areas of sealing contact may result, and the seal-maintaining effect will depend on the resilience of the sealant itself, thus limiting the choice of sealants and possibly not providing sufficient seal maintenance with some materials.

Figures 4A and 4B show the preferred sealing member 40, similar to that of Figure 3, between overlapping joint surfaces 42, 44. Figures 4C and 4D illustrate a corresponding joint using a less compressible solid body 46 of sealant, with disadvantages similar to those described for Figure 3.

Figure 5A shows the preferred sealing member 50, similar to that described for Figure 3, in a hypothetical stepped butt joint formed by components 52 and 54. Even in such a confined sealing space, the gas-containing carrier of the present invention permits relatively easy compression of the sealing member to form a seal as indicated schematically in Figure 5B. This could be extremely difficult with a solid body of sealant, owing to the shortage of space to take up the distortion of such a substantially incompressible solid body.

Figure 6 shows in perspective a moulded sleeve housing 60 designed for enclosing splices in electrical and/or optical telecommunications cables. The cables (not shown) enter and leave through entry and exit ports in end pieces known pex ≤£ (not shown) and the sleeve 60 is wrapped around the end pieces to enclose the splices in the parts of the wires or optical fibres (not shown) which lie between the end pieces. The sleeve 60 is then closed by means of a projection or tongue 62 and groove or channel 64 extending along its opposed edges. As shown schematically in more detail in Figure 7A, the channel 64 has positioned therein a sealing member 66 according to this invention. On insertion of the projection 62 into the channel 64, the sealing member 66 is compressed to form a gel seal as shown in Figure 7B. A locking clamp 68, of generally channel-like configuration, is slid on lengthwise from the end of the tongue and channel formations to hold the joint together (Figure 7B). Snap-fit or other fastenings could be used if desired. Figure 8A shows schematically in perspective a section of a simplified two- part housing such as might, for example, contain the working parts of a gas or electricity meter. The top part 80 (as illustrated) has a projecting tongue 82 designed to fit into a corresponding slot or channel 84 in the lower part (as illustrated) 86. The channel 84 contains a tubular sealing member 88 according to the present invention, which is compressed to form a gel seal on assembly of the tongue-and-groove joint in the housing, as illustrated in Figure 8B. Of course, many different shapes and arrangements of such housings occur in practice to suit the needs of the particular gas meter or other equipment to be enclosed, and all may be sealed by one or another of the sealing member configurations according to this invention.

Figure 9 shows a headlamp housing comprising a moulded polypropylene backshell 90 having a rear aperture 92 to receive the lamp bulb mounting and a circumferential channel 94 containing a sealing member 96 according to the present invention, which has been cut to the required circumferential length and joined together at its ends to lie securely in the channel 94. The headlamp lens 98 has a projecting circumferential lug or tongue 100 designed to fit into the channel 94 thus compressing the sealing member 96 to form a sealed tongue-and-groove joint. Retaining clips or other means (not shown) may be used to secure the lens 98 and backshell 90 together.

The provision of the tubular body of sealant on a carrier according to this invention enables the sealing member to be produced in long continuous lengths for laying into channels or other sealing locations in whatever lengths are usually required.

By way of example, a preferred gel comprising 11 % by weight of "Septon" 4055 (Trade Mark) SEPS triblock copolymer and 4% of "Septon" 1001 styrene- (ethylene/propylene) diblock copolymer with substantially non-aromatic extender oil as described in the aforementioned WO-A-9323472 was fed into the co- extrusion head of a 32 mm Baughan extruder (known pex se) for co-extrusion onto extruded-tube carriers of the following polymers, with the indicated qualitative adhesion results: Carrier Polymer Adhesion

EVA (Elvax 470, 18% VA) Excellent

Polypropylene/Polyethylene blend Fair

Low Density Polyethylene (Dow LD 150) Fair/Good

High Density Polyethylene Fair/Poor

Very Low Density Polyethylene (Plastomer) Exxon Excellent Engage CL8001

EMA Copolymer (Lotryl 14MG02) Excellent

Polyester/Polyether elastomer (Hytrel G4074) Poor

Polypropylene/EPDM Blend (Sarlink 3140) Fair

"Excellent" indicates that the gel could not be delaminated from the carrier; "Fair" that it could be delaminated; and "Poor" that it could be very easily delaminated. Even "Fair" or "Poor" adhesion may be acceptable for some purposes of the present invention.

The relative diameters and wall thicknesses of the tubular body of sealant and the carrier are not critical, and may- be selected to suit specific end uses, bearing in mind that smaller carrier diameters may tend to limit the advantageous deformability of the sealing members. Where foams are used in the carrier, higher density foams may also tend to limit the compressibility of the sealing members, but the choice may otherwise be freely made to suit practical needs. It may be desirable in many cases to use a gel coating whose radial thickness is less than 0.5 times, preferably less than 0.25 times the carrier outer radial dimension. For circular carriers and sealant tubes, in other words, the thickness of the tubular sealant layer may usefully be less than one third, preferably less than one sixth, of the outer radius of the gel tube. The carrier wall thickness (for hollow tubular carriers) will preferably be not less (often considerably greater) than the sealant thickness, but thicker layers of sealant may be useful in some circumstances, e.g. for void filling. Variations from, and within, these preferred ranges of radii and/or wall thicknesses may be selected to suit particular requirements. Overall diameters ranging from a few millimetres to a few centimetres, preferably 0.25 cm to 3 cm, especially 0.5 cm to 2 cm, are likely to be useful in most cases. For avoidance of doubt, the term "tubular" as used herein is to be understood as including any elongate hollow body resembling a pipe or conduit, regardless of its cross-sectional shape.

One may add to the above the use of polysiloxane elastomeric material to enhance resistance to compression setting of the sealing members. This enhancement may be achieved by using the polysiloxane elastomer material (or a blend of polymers containing it) as the internal carrier according to the aforementioned application. In this case, the adhesion of the sealant to the carrier may require enhancement, either by means of primer coatings or by provision of fibrous layer as described and claimed in our co-pending British Application 9425393.7(B288); or the sealant, if sufficiently cohesive, may be able to form a tube surrounding the carrier with little or no adhesion to it.

Alternatively, the aforesaid enhancement may be attained by placing the polysiloxane elastomer material or blend inside a tubular internal carrier made of another material, for example one of those described in the aforementioned application 9419035.2. In this case, the tubular carrier may act as a sleeve fitted over a member formed from the polysiloxane elastomer as claimed in the aforementioned application (B288). The elastomer may itself be in the form of a hollow tube of circular or other profile, or may be in the form of a foam.

Suitable methods for forming the sealing members including the polysiloxane elastomers will readily be selected in general from known co-extrusion and other coating and/or moulding techniques.

It has also been discovered that, when the carrier itself is tubular with a hollow bore, the bore diameter is preferably not more than 60% (and not less than 5 % , preferably not less than 10% , of the total outside diameter). The remaining 40% of that diameter is made up of the tubular carrier and the tubular gel on the outside surface of the carrier. It has interestingly been found by mathematical modelling that with "thick" gel layers (that is, layers whose thickness is greater than the thickness of the carrier), the gel characteristics dominate, so that changes in the hardness of the carrier material have relatively little effect on the compression forces required to distort the sealing member in a "channel-and-lid" sealing arrangement, as illustrated in the accompanying drawing. When "thick" carriers (thicker than the gel layer) are used, the carrier hardness tends to dominate the compression force, which is relatively unaffected by changes in the gel hardness. When the gel and carrier are of approximately the same thickness as each other, it has been found that a pair of "thick" layers (each of thickness greater than 10%, preferably greater than 15%, of the overall diameter) tend to be dominated by the gel hardness, whereas a pair of "thin" layers (each of thickness less than 10% of overall diameter) tend to be dominated by the carrier hardness. These findings are especially applicable to the generally useful range of sizes around 10 mm overall diameter for substantially round tubes, and are likely to be preferred for diameters ranging from 2 to 30 mm, preferably 5 to 20 mm.

These aspects of the invention are further illustrated by the accompanying drawings wherein :-

Figure 10 and 11 show schematically a tubular gel profile seal in a channel- and-lid sealing arrangement.

In the drawings, Figure 10 shows schematically a sealing article according to the invention having a polysiloxane elastomer carrier 101 carrying a tubular coating of gel 102, the carrier and the gel being of approximately the same thickness, and a substantially central substantially round hole 103. The diameter H of the hole 103 (not shown to scale) will be not more than 60% of the total outside diameter; which is equal to the hole diameter H plus twice the carrier thickness C and twice the gel thickness G. This sealing article is shown in a channel 104 onto which a lid 105 is ready to be pressed. Figure 11 shows the lid pressed into position on the channel, thus compressing the sealing article and causing the gel to form a seal against the lid and the sides and bottom of the channel. The pressure resistance of the seal tends to increase with increasing hardness of the carrier and/or the gel, which also increase the compressive forces required to close the lid and deform the sealing member.

Typical gels might have a Voland hardness of 60 gms (11.5% Septon (Trade Mark) 2006 and 4.5% Septon 1001 with remainder non-aromatic oil); or Voland hardness of 100 gm (14% Septon 2006 and 8% Septon 1001 with remainder non- aromatic oil). Typical carrier materials might be Sarlink (Trade Mark) thermoplastic elastomer of Shore hardness 40, 60 or 80, or Thermolast (Trade Mark) thermoplastic elastomer of Shore A hardness 25.

Another useful form of sealing member according to the present invention, derived from those hereinbefore described, is one whose tubular length is less than its largest outer diameter, preferably less than half, more preferably less than one quarter, of its largest outer diameter. Such sealing members may be regarded as rings (usually substantially circular, although other configurations are not excluded), which may have been formed by cutting from a longer length of the tubular sealing member. Other methods of making such relatively short tubes or rings may be envisaged, but cutting from longer lengths is usually more convenient in practice. The expression "largest outer diameter" is intended to include shapes other than substantially circular.

These ring-like sealing members may advantageously be put to use as a gasket between opposed pressure surfaces, or as a grommet on an elongate object (e.g. a wire) passing through the sealing member, especially where it is desired to seal a larger aperture through which the elongate member also passes, which aperture fits closely around the perimeter of the grommet provided by the ring-like sealing member.

In another useful application of the present sealing technology, an elongate sealing member as hereinbefore described may be arranged with one of its ends in endwise abutment with its own other end or with an end of another such sealing member, wherein the said sealant material is present at both of the said abutting ends and seals them together, possibly without any additional means attaching the ends to each other. The sealant material (preferably gel) has been found surprisingly effective in maintaining a seal between the abutting ends of sealing members arranged in a closed loop or circle when compressed in use in a channel- and-lid or tongue-and-groove sealing arrangement. Additional attaching means such as adhesives or a solid peg extending into an internal bore at the abutting ends may also be used if desired. A hollow attachment pin, which advantageously transmits internal gas pressure across such an abutting end joint in a hollow tubular sealing member, is described in co-pending British Patent Application 9424137.9 (B287).

In all forms of the sealing members herein described, it is possible that the perimeter of the tubular body of sealant material extends only partly around the carrier, thus foπriing an open-sided tubular body of the sealant material. Such an open-sided tubular body would not include a flat sheet carrying a layer of the sealant material on only one of its main surfaces, but includes structures wherein the sealant material extends partway around the carrier rather than completely around it, and includes both rounded and angular open tubes, for example where the sealant extends partway (preferably more than halfway, more preferably more than three quarters of the way) around a round or elliptical carrier or around more than one side of an angular carrier, e.g. around three sides of a square or rectangular carrier.

In most forms of the various aspects of this invention, it will be preferable that the carrier is substantially continuous and substantially free of voids (meaning unintended voids).

Preferred forms of the articles for certain purposes are those wherein the carrier includes a formation, preferably integral with the carrier, for attaching the carrier to an object which is to carry the article in use. In these cases, although the carrier and the attaching formation could be completely enclosed by a coating of sealant (preferably gel), it will frequently be preferable that the sealant encloses only the part of the carrier constituting its main body, which in use will perform the sealing function, leaving the attaching formation free of sealant. Thus, the partial enclosure of the carrier by the sealant hereinbefore referred to may be preferred in these cases. The attaching formation may take any appropriate form, one preferred form being a projection having an enlarged region receivable in use in an aperture in the said object to anchor the carrier thereto. The attaching formations need not be, but preferably are, integral with the carrier, the carrier and attaching formation preferably being moulded or extruded or otherwise formed as one piece. The attaching formation may itself be hollow, either as a continuation of a hollow tubular carrier or as a separate hollow body attached to the hollow carrier, or the attaching formation may be solid. Hooks or other convenient formations may be used for the attaching formation as desired, but the aforementioned projections with enlarged regions will often be convenient in use, especially those having an enlarged "head" which may be snap-fitted or slid into a slot in the object to which the article is to be attached.

These attachable aspects of the invention may provide articles which are especially suitable for long seals attached, for example, to objects such as windows or doors to provide seals at the closure interface, for example between the window frame and its casement. This may be particularly advantageous in double glazing constructions. The attaching projection or "lug" will often extend all the way along the carrier, but may if preferred be formed only at intervals along it.

It will be appreciated that, instead of having an identifiable attaching formation as described above, the sealing profiles according to this invention could simply be shaped as a whole and accommodated in a slot or aperture of appropriate shape to enable part of the profile to project for sealing purposes. Whatever the form of profile selected, the co-hesive strength, flexibility, and sealing characteristics of gels, especially the preferred gels hereinbefore mentioned, may be highly advantageous in circumstances requiring frequent re-opening and re-closing of the seals, for example doors and windows as aforesaid.

Articles according to this and other aspects of the invention may be useful, for example, for laying along surfaces of articles or in channels formed in articles to provide a gel sealant on or in those articles for sealing against other surfaces with which the articles will be in contact in use.

Especially preferred articles according to the various aspects of this invention are those wherein the sealant is a gel which comprises a thermoplastic triblock copolymer having a fluid-extended elastomeric mid-block and having end blocks (preferably polystyrene or polymethacrylate end blocks) which are substantially impervious to the extender liquid of the mid-block, and the carrier is of plastics material, for example comprising ethylene/vinylacetate copolymer as a majority by weight of the polymer content.

The triblock copolymer gels will preferably have the characteristics and meet the criteria described in any or all of EP-A-0426658 (RK308), WO-A- 9305113 (RK451), WO-A-9323472 (RK469), and WO-A-9418273 (RK472), the disclosures of all of which are incorporated herein by reference. Those disclosures deal mainly or wholly with triblocks having polystyrene end blocks. For higher temperature performance, it may be preferable to use the new triblock gels having polyalkylmethacrylate end blocks described in our co-pending British Application (RK509).

These further embodiments of the invention will now be illustrated by way of example with reference to the accompanying drawings, wherein: -

Figure 12 shows an O-ring seal cut from a tubular sealant article as hereinbefore described;

Figures 13 and 14 show in plan and transverse cross section respectively the use of an O-ring seal as shown in Figure 1 as a gasket in a pipe coupling;

Figure 15 shows in perspective the use of a small-diameter ring seal as a grommet on a wire passing through a conduit;

Figure 16 shows schematically a butt joint as hereinbefore described between tubular sealing members; Figure 17 shows a tubulart profile similar to that described in the aforementioned co-pending British Application No. 419035.2, with the addition of an arrow-headed projecting formation fixing the profile in a channel between two sealing surfaces; and

Figure 18 shows a profile comprising a generally triangular hollow carrier completely enclosed by gel positioned in a groove shaped to retain the profile in one of a pair of sealing surfaces with part of the profile projecting from the groove to perform the sealing function.

Referring to the drawings, Figure 12 shows a tubular sealing member having a tubular carrier 50 and an outer coating of gel 52 adhering to the outer surface of the carrier as described in the first two aforementioned co-pending applications. A thin ring 54 is shown having been cut from the tubular member for use as a gasket or grommet as hereinbefore described.

In Figures 13 and 14, a coupling between two sections of pipe 60 and 62 is schematically shown using a gasket O-ring 54 generally similar to that illustrated in Figure 12. The gasket 54 sits on a step formed in the end of pipe section 62 and is compressed when the section 62 is assembled with interlocking section 60. The transverse cross-sectional view of Figure 14 is taken on the line 3-3 of Figure 13.

Figure 15 shows a grommet 80, which is essentially a smaller-diameter version of the O-ring shown in Figure 12, fitted on an insulated electrical wire 82 passing through a transparent conduit 84, against which the outer gel coating of the grommet 80 makes a seal. The resilient carrier 86 of this grommet fits tightly around the wire 82.

Figure 16 shows schematically a butt end seal 90 between tubular sealing member ends 92 and 94 within a schematically-indicated groove or channel 96 of a channel-and-lid or tongue-and-groove sealing arrangement. Gel sealant carried on the tubular carriers of the sealing articles 92 and 94 is indicated schematically at 98 and seals the abutment 90 between the ends.

Figure 17 shows another form of profile in which the gel 71 adheres to a hollow carrier 70 having an arrow-headed fixing lug 72 engaged in slot 73 of a first body 74 mateable with a second body 75 so that the sealing article can perform its sealing function. The mateable bodies 74 and 75 may for example be protective housing parts for enclosing electrical or other equipment, for example wire or cable joints, optical fibre joints, or gas meter working parts, or may be door or window closure members as hereinbefore mentioned. The materials for the carrier and gel may be selected for convement manufacture and to suit the end uses in question, the gel preferably adhering reasonably strongly to the carrier in this form of article. Preferred materials are those mentioned in the aforementioned co-pending applications, the disclosures of which are incorporated herein by reference.

In Figure 18, a triangular rod-like hollow resilient carrier 40, completely enclosed by gel 41, has been forced-fitted or longitudinally slid into groove 42 formed in one of a pair of mating bodies 43, 44 (for example protective housings or closure members as aforesaid). A portion 45 of the more-or-less triangular profile projects from the groove 42 so as to form a gel seal against the mating surface 44 in use. The groove 42 has been shaped as shown to allow space for distortion of the profile under sealing pressure.

Claims

CLAIMS:

1. A sealing member comprising a tubular body of sealant material carried by an internal (to the tubular body) flexible (preferably resiliently-flexible) gas- containing carrier, the sealant material having a cone penetration within the range from 80 to 400 (lO'lmm) and an ultimate elongation of at least 100%, preferably at least 200%, more preferably at least 500% .

2. A sealing member according to claim 1, wherein the carrier and/or the body of sealant material is tubular, preferably a rounded, more preferably a substantially circular, tube.

3. A sealing member according to claim 1 or 2, wherein the carrier is or includes foamed polymeric material, preferably having open foam cells.

4. A sealing member according to any preceding claim, positioned on a first body, preferably in a channel formed in the first body, which is capable of receiving a portion of a second body to compress the sealing member thus to form a seal between the first body and the second body.

5. A sealing member according to claim 4 positioned in an angular channel, preferably a substantially rectangular channel, in the first body.

6. A sealing member according to claim 4 or 5 forming a seal within a tongue- and-groove type connection between the first and second bodies.

7. A sealing member according to any preceding claim, wherein the sealant material has been applied in a molten state, and preferably under elevated pressure, to the carrier, preferably with at least a surface region of the carrier being or becoming molten or softened while in contact with the molten sealant material.

8. A sealing member according to claim 7, wherein the carrier is an extruded article and the sealant material has been applied during or immediately after the extrusion of the carrier, preferably by co-extrusion with the carrier.

9. A sealing member according to claim 7 wherein the sealant material has been extruded onto a pre-formed carrier.

10. A sealing member according to any preceding claim, wherein the adhesion strength of the sealant material to the carrier is greater than its adhesion strength to a body with which it is to be placed in sealing contact in use.

11. A sealing member according to any preceding claim, wherein at least the outer surface region of the carrier is composed of, or comprises as a majority component, an olefin copolymer, preferably ethylene/vinyl acetate copolymer containing less than 40%, preferably less than 20%, by weight of vinyl acetate, ethylene/alkylacrylate copolymer containing less than 40%, preferably less than 20%, by weight of alkylacrylate, or polyethylene, preferably low-density polyethylene.

12. A sealing member according to any of claims 1 to 10, wherein at least the outer surface region of the carrier is composed of, or comprises as a majority component, elastomer material, preferably thermoplastic elastomer material.

13. A sealing member according to claim 12, wherein the elastomer material is or includes very low density polyethylene plastomer, polyether /polyester block copolymer, or a polypropylene/EPDM blend.

14. A sealing member according to any preceding claim, wherein the sealant material is a gel, preferably a thermoplastic gel.

15. A sealing member according to claim 14, wherein the gel has substantially elastic deformation up to an elongation of at least 100%.

16. A sealing member according to claim 14 or 15, wherein the gel has ultimate tensile strength (ASTM D412) less than 1 MPa, dynamic storage modulus less than 50 kPa, and substantially zero slump at temperatures up to 100°C, preferably up to 120°C.

17. A sealing member according to claim 14, 15 or 16, wherein the sealant material is a gel comprising

(i) a styrene-alkylene block copolymer, preferably a styrene- (hydrogenated alk lene)-styrene triblock copolymer, more preferably a styrene- (ethylene/propylene and/or ethylene butylene)-styrene triblock copolymer having a weight average molecular weight Mw of at least 180,000, and

18. A sealing member according to any preceding claim, whose tubular length is less than its largest outer diameter, preferably less than half, more preferably less than one quarter, of its largest outer diameter.

19. A sealing member according to claim 18, which has been cut from a longer length of the tubular sealing member.

20. A sealing member according to claim 18 or 19 in use as a gasket between opposed pressure surfaces, or in use as a grommet on an elongate object passing through the sealing member.

21. A sealing member according to any preceding claim, arranged with one of its ends in endwise abutment with its own other end or with an end of another such sealing member, wherein the said sealant material (preferably gel) is present at both of the said abutting ends and seals them together, preferably without any additional means attaching the ends to each other.

22. An article according to any preceding claim, wherein the carrier includes a formation, preferably integral with the carrier, for attaching the carrier to an object which is to carry the article in use.

23. An article comprising an elongate tubular carrier carrying an elongate body of gel and including a formation, preferably integral with the carrier, for attaching the carrier to an object which is to carry the article in use.

24. An article according to claim 22 or 23, wherein the said formation comprises a projection with an enlarged region receivable in use in an aperture in the said object to anchor the carrier thereto.

25. An article according to any of claims 22 to 24, wherein the said formation is hollow.

26. An article according to claim 25, wherein said formation is integral with the carrier and the hollow within the said formation communicates with the hollow within the carrier.

27. A sealing member according to any preceding claim, wherein the perimeter of the tubular body of sealant material extends only partly around the carrier, thus forming an open-sided tubular body of the sealant material.

28. An article according to any preceding claim, wherein the carrier comprises polysiloxane elastomer material.

29. An article according to any of claims 22 to 27 in use as a door or window seal.

30. A method of forming a sealing member according to any preceding claim, comprising applying a closed or open-sided tubular layer of the said sealant material in a molten state to the said carrier and causing or allowing the applied sealant material to solidify.

31. A method according to claim 30, comprising extruding the carrier and applying the sealant material thereto during or immediately after the extrusion of the carrier, preferably by co-extrusion with the carrier.

32. A method according to claim 30, comprising extruding the sealant material onto a pre-formed carrier, preferably after wanning the carrier surface.

33. A method of forming a seal between a first body and a second body comprising placing a sealing member according to any of claims 1 to 28 in contact with a portion of the first body and bringing a portion of the second body into compressive contact with the sealing member so as to compress that sealing member between the first and second bodies.

34. A housing component for electrical or other apparatus the housing component carrying a sealing member according to any of claims 1 to 28 and the sealing member being positioned on the housing component so as to form a seal between the housing component and another body with which the housing component will be assembled in use, preferably with compression of the sealing member.

35. A housing component according to claim 34, carrying the sealing member in a channel arranged to receive a mating part of the said other body in use to form a sealed connection, preferably a tongue-and-groove type of connection.

36. A housing component according to claim 34 or 35 assembled together with the said other body.

37. A kit of parts comprising a housing component and a sealing member capable of being assembled to provide a housing component according to claim 34 or 35.

38. A kit according to claim 37, additionally comprising another body, preferably a second housing component, capable of assembly together with the said housing component to compress the said sealing member to form a seal between the said housing component and the said other body.

39. A kit of parts comprising a door or window component and an article according to any of claims 1 to 28 capable of acting as a seal in a door or window assembly to be formed using the said kit.

40. A door or windor component carrying an article according to any of claims 1 to 28.