WO1996018836A1

WO1996018836A1 - Sealing article

Info

Publication number: WO1996018836A1
Application number: PCT/GB1995/002881
Authority: WO
Inventors: Jesper Damn; Jacob Abboud; Valere Buekers; Patrick Clits; Luiz Neves Mendes
Original assignee: N.V. Raychem S.A.
Priority date: 1994-12-14
Filing date: 1995-12-11
Publication date: 1996-06-20
Also published as: AU4122196A

Abstract

Flexible tubular sealing article has carrier with sealant (gel) in one or more surface depressions (D) (fig. 3) running along its length, with specified relationship between internal bore width (W) and the varying carrier wall thickness maximum (t) between the depressions and minimum (t') underlying the depression. Sleeves and fibrous layers may enhance adhesion of the gel to the tubular carrier. In one version, the carrier depressions may be of re-entrant form (fig. 11) partly surrounding the outer surface of the sealant. Various joint-sealing uses are described.

Description

SEALING ARTTCI.F,

This invention relates to a flexible article 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 nςw form of sealing member having considerable advantages over known kinds for various purposes.

The invention accordingly provides a flexible tubular article of polymeric material having an internal longitudinal (preferably substantially circular) bore whose maximum transverse width is not more than three times (preferably not more than twice, more preferably not more than 1.5 times) its minimum transverse width, and having externally at least one (preferably at least two) longitudinally extending surface depression(s) so arranged that

(a) the maximum wall thickness of the polymeric material between the perimeter of the internal bore and the external surface of the tubular article (preferably between the said depressions) is not more than three times (preferably not more than twice) the said maximum (preferably minimum) bore width, and the minimum wall thickness of the same (preferably underlying the said depressions) is not less than 25% (preferably not less than 50%, more preferably not less than 75%) of the said minimum (preferably maximum) bore width, and (b) the depth of each of the said depressions extends to at least 10% (preferably at least 20%, more preferably at least 30%) of the said maximum wall thickness.

Articles according to this invention may be advantageous in teπns of the defmed relationships between bore width and wall thickness resulting in reduced deformation stress and increased reliability of sealing, especially when provided with sealant materials as hereinafter described; and especially when the maximum transverse dimension excluding any sealant layer or sleeve is not more than 20 mm, preferably not more than 15 mm; and not less than 2.0 mm, preferably not less than 3 mm, more preferably not less than 5 mm; and preferably the average transverse width of the said internal bore is less than 60% of the maximum transverse dimension, e.g. less than 6 mm, preferably not more than 5 mm, more preferably not more than 4 mm, for a maximum transverse dimension of 10 mm, and is at least 0.5 mm, preferably at least 1.0 mm. For many purposes, it may be preferred that the said maximum transverse dimension is within the range from 2 mm to 5 mm or within the range from 5 to 10 mm or within the range from 10 to 15 mm.

The transverse shape of the internal bore is not critical, and may for example be irregular, or triangular, rectangular or hexagonal, but is preferably rounded, more preferably substantially elliptical, especially substantially circular. References herein to the transverse width of the bore will be understood to mean the width as seen in an end view or cross-section looking along the longitudinal tubular axis. The maximum and minimum transverse width of the bore will be understood accordingly, for example meaning the major and minor axes of an elliptical bore which approach each other in length as the elliptical shape approaches a true circle. The average transverse width will be understood as the mean of the maximum and minimum widths for regular shapes, or as the mean of a suitable number of transverse measurements for irregular shapes.

The wall thickness of the polymeric material between the perimeter of the bore and the outer surface of the article will normally be measured on lines radiating from the central tubular axis of the bore for regular cross-sectional bore shapes, but may be measured on lines normal to the bore surface if necessary or preferred. Thus, for the preferred substantially circular bore shape, the wall thickness will be between 20% and 300%, preferably between 25% and 200%, of the bore diameter, with the variation from minima underlying the surface depressions to maxima between them being at least 10% of the maximum wall thickness to produce the depth of depressions stated above. Although, in theory, the internal bore could be shaped to make the wall thickness between the surface depressions less than that underlying the depressions, this is likely to be less useful in practice.

Irregular cross-sectional shapes for the article and/or for the internal bore are not necessarily excluded, but it is in most cases preferable for the article to have the said surface depressions symmetrically arranged about its tubular axis. Depending on the end uses of the article, it may sometimes be useful to have only one or two of the surface depressions, or to have many, forming a multi-grooved or scored surface, but it is more usually preferred to have at least three and not more than twelve (preferably not more than ten) of the said surface depressions. Especially useful are such articles having four depressions. Rounded articles having the said surface depressions) are conceivable, but preferred external shapes for the articles of this invention are those whose transverse cross-sectional outline is substantially a 3-, 4-, or more-sided polygon with each of its sides incorporating a respective one of the said depressions, which depressions preferably occupy more than 50%, more preferably more than 70%, of their respective polygon sides. The depressions might be flat-bottomed with straight, sloping or curved sides, but preferably the majority of each side of the said polygon outline is formed by a concave surface of the polymeric material. Preferably, each corner of the said polygon outline is formed by a convex surface of the polymeric material whose convex perimetric length is less than (preferably less dian half) that of the adjacent concave surface(s). Such concave and convex surfaces need not be strictly circular or regular in curvature. Three- or four-sided shapes are advantageous for resisting rolling of the sealant article along surfaces with which it is in contact in use. It may be preferable for the average transverse bore width to be not more than 60% of the notional polygon side length.

For sealing purposes, it is preferred that at least one (preferably at least two) of the said surface depressions carries an adherent layer of sealant material capable of forming a seal between the article and a surface against which the article carrying the sealant will be pressed in use. The sealant material may only partly or wholly occupy the surface depression carrying it, in which case it need not extend circumferentially beyond the relevant surface depression and preferably adheres to surface depressions, preferably extending around the whole circumference of the article.

Alternatively, the article may have fitted thereon ( by methods hereinafter described) a tubular sleeve which surrounds the article and is capable of forming a seal to a surface against which the article carrying the tubular member will be pressed in use. The sleeve may follow closely the surface of the underlying article or may bridge across the said surface depressions and preferably carries on at least part of its exterior surface on adherent layer of sealant material. Suitable sealant- carrying sleeves may be selected from the tubular sealing members described and claimed in our co-pending British Patent Application No. 9419035.2 (RK508), the disclosure of which is incorporated herein by reference.

The invention thus includes all forms of a sealant article comprising a flexible tubular inner member of polymeric material (preferably elastomeric material) carrying a surrounding sleeve of polymeric (preferably elastomeric) material and a layer of sealant material (preferably gel) adhering to the outer surface of the sleeve so that the sealant can be brought into sealing contact with a surface against which the article will be placed in use.

In all cases, the sealant material preferably extends along substantially the whole length of the article. The sealant material may be selected from materials known for such purposes, but is preferably a gel, especially where re-opening of the seal will be desired in practice. Desirably, the sealant material is a thermoplastic gel, preferably a triblock copolymer gel. Gel sealants will be described in more detail hereinafter.

In some cases, it may be desirable or necessary that an adhesion-promoting layer is provided to cause or enhance the adhesion of the sealant material to the underlying surface. One form of such adhesion-promoting layer comprises fibrous material, preferably enclosing the said article or sleeve providing the said underlying surface. Suitable fibrous materials include glass fibres and/or melt-spun fibres of thermoplastics, for example polyolefins, nylons, polyesters. The fibrous material may be braided, woven, or wrapped around the tubular article of this invention, and it is envisaged that fibrous adhesion-promoting layers may be useful and inventive in their own right for causing or enhancing the adhesion of sealant (preferably gel) layers to carriers of any suitable (tubular or solid) form. In one possible alternative, the adhesion-promoting layer comprises a coating of polymeric material which adheres to the sealant material and to the said underlying surface more strongly than the sealant material itself adheres to the said underlying surface. Suitable "primer" coatings of this kind may be selected from polymeric materials known for such purposes, for example polymer latex materials, resin solutions, or melt coatings, possibly containing reactive coupling agents.

Suitable materials for the article having the internal bore and surface depressions according to the present invention may readily be selected from known plastics and polymeric materials. Desirably, the said polymeric material having the internal bore is at least partly composed of elastomeric material, preferably a polysiloxane-based elastomeric material. Polysiloxane elastomers are especially preferred for end uses where resistance to compression set is important. Since low adhesion of sealants to polysiloxanes can be a problem, it may be especially preferable to use the aforementioned adhesion-promoting layers or the aforementioned sleeve carrying the sealant.

Theoretically, the parameters hereinbefore specified may apply proportionately to sealant articles of any size. However, in practice it has been determined that useful sealant articles are preferably those whose maximum transverse dimension excluding any sealant layer or sleeve is not more than 20 mm, preferably not more than 15 mm; and not less than 2.5 mm, preferably not less than 5 mm, and often not less than 10 mm. At least in articles of these preferred dimensions, it is desirable that the average transverse width of the said internal bore is less than 60% of the maximum transverse dimension. For example, in articles of about 10 mm maximum transverse dimension, bore width is less than 6 mm, preferably not more than 5 mm, more preferably not more than 4 mm, and is at least 0.5 mm, preferably at least 1.0 mm.

This invention includes the use of the sealing articles as a component of a ring, sandwich, channel-and-lid, or tongue-and-groove sealing arrangement, preferably with a sealant material carried by the article forming a seal against another surface of the said sealing arrangement.

In this context, a "ring" sealing arrangement may be understood, for example, as an 0-ring structure formed by joining together the ends of a length of sealant article according to the invention. This joining may be done by means of adhesive, or by fitting the respective ends of the bore over a coupling rod or preferably a hollow coupling tube to provide continuity of gas pressure distribution around the ring. A "sandwich" sealing arrangement for example is one in which the sealing member is compressed between two opposed surfaces, usually without close lateral confinement in the direction parallel to those surfaces. A "channel- and-lid" sealing arrangement for example has the sealing article in a fairly close- fitting channel, hollow or groove across which is placed a lid-like closure member which compresses the sealing article. The sealing article may project out of the groove or hollow for compression by a flat closure member, or may lie wholly within the groove or hollow and be compressed by a closure member having a flat portion extending slightly into the channel or hollow. A "tongue-and-groove" sealing arrangement may for example having the sealing article at least partly within a groove or hollow into which a tongue-like projection is relatively deeply inserted in use to deform or crush the sealing article. References in this context to a sealant material "carried by the article" will be understood to include not only the sealant being in direct contact with the surface of the article, but also the sealant being on a sleeve fitted over the article as aforementioned.

It will be understood that the provision of a body of sealant material on an article 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 article shape and dimensions have the advantage that the article can be deformed by compression, to make good contact with the surfaces to be sealed, using considerably less total force than would be required with other forms, and with concentration of the resilient sealing forces at the corners or "high points" between the surface depressions. The preferred use of a resiliently-flexible article has the additional advantage that the resilient recovery force of the deformed article can be used to maintain sealing under compression against the surfaces to be sealed, which is especially desirable when the article carries a sealant gel as hereinbefore described. For some purposes however, adequate seals may be formed with very slight compression of, or possibly mere contact with, the body of sealant.

The invention includes the sealing article 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 article. The channel in which the sealing article may be placed may be of any shape to suit the shape of the sealing article. However, mathematical modelling indicates that desirable stress distributions may be achieved when the sealing article is positioned in an angular channel, preferably a substantially rectangular channel, in the first body, to form a seal by compression of the sealing article between the first and second bodies.

The sealing articles 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 article may be cut to length, and may when required be joined together at its ends to form a closed loop or ring as aforementioned.

The invention accordingly includes a method of forming a seal between a first body and a second body comprising placing a sealing article 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 article 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 article according to this invention and the sealing article 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 article 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 article 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 article 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 part, capable of assembly together with the said housing component to compress the said sealing article to form a seal between the said housing component and the said other body.

In preferred sealing articles according to this invention, the sealant material has been applied in a molten state, and preferably under elevated pressure, to the carrier (the article itself or especially the aforementioned sleeve), 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 intermingled 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 article 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, as aforementioned.

The invention accordingly includes a method of forming a sealing article according to this invention, comprising applying a (preferably tubular) layer of the said sealant material in a molten state to the said carrier (the article having the surface depressions or the aforementioned sleeve) 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) acrylate 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;

poly ether/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).

For optimum resistance to compression set, polysiloxane elastomers are preferred, as aforementioned.

As previously mentioned, the sealant material is preferably a gel, more preferably a thermoplastic gel. 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 article according to this invention the sealant material is a gel comprising

(i) a styrene-alkylene-styrene triblock 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 200 (preferably at least 300 or 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 2-30 weight % of styrene-alkylene block copolymers based on the weight of the whole composition, especially those comprising from 4% to 20% by weight of the SEPS copolymer and at least 400, preferably at least 500 parts by weight of extender liquid per 100 parts by weight of the gelling polymer, in which the SEPS 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.

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, wherein: -

Figures 1A to ID show schematically in perspective four possible configurations for the sealing article according to the invention with the preferred sealant omitted for clarity;

Figure 2 shows schematically in cross-section a preferred "four-sided" form of the article according to this invention carrying sealant material in two of its four surface depressions, positioned between two other surfaces in an example of a "sandwich" sealing arrangement;

Figure 3 shows schematically in cross-section an article similar to that of Figure 2 with the sealant covering its whole perimeter, in an example of a "channel-and-lid" sealing arrangement;

Figure 4 shows, in a manner similar to that of Figure 3, an article according to this invention having a sealant-coated sleeve bridging its surface depressions, in an example of a "tongue-and-groove" sealing arrangement;

Figure 5 shows schematically 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 1A shows a possible polymeric sealing article of substantially round profile of overall diameter MD having two surface depressions D of depth d symmetrically arranged on opposite sides. In this example, the depressions D have concave surfaces throughout and occupy much less than half of the total circumference of the article. An internal bore B, in this example substantially centrally positioned, is triangular with a maximum transverse width w (equal to its side length) only slightly greater than its minimum transverse width w' (equal to its height). The maximum wall thickness t of the polymeric material is about twice w and the minimum wall thickness t' is slightly greater than w' . If the maximum transverse dimension MD (not to scale) is taken as 10 mm, the average transverse width of the bore B would be slightly more than 2 mm.

Figure IB shows another possible article having a roughly triangular profile with three surface depressions D of depth d formed by concave surfaces which occupy more than half of the total perimeter, joined together by convex surfaces at the "points" P of the "triangular" profile. In this example, the bore B is again centrally placed, but is substantially square. The maximum wall thickness t is about 1.25 times the maximum transverse bore width w, while the -r-i-nimum wall thickness t' is less than the minimum transverse bore width w' . For MD of about 10 mm, the bore would have an average transverse width of about 2.5 mm.

Figure IC shows another possible article based on a roughly hexagonal profile having six surface depressions D of depth d. In this example, the depressions D have flat bottoms and straight sides. The substantially centrally-

S placed bore B is substantially elliptical, with maximum transverse width (the major elliptical axis) equal to about 2.5 times the minimum transverse width w' (the minor elliptical axis). The maximum wall thickness t is about 1.5 w and the minimum wall thickness t' is about 1.5 w' (0.75 w in this example). An MD of about 10 mm would suggest an average bore width of about 2.5 mm.

Figure ID shows another possible article based on a roughly rectangular profile having four surface depressions D of depth d. The depressions D shown on the top and bottom in this figure illustrate the possibility of depressions having flat bottoms with sloping sides, while the depressions on the left and right sides are formed by concave surfaces throughout. These respective concave and sloping surfaces meet at four relatively sharp points P, giving a maximum wall thickness t about twice the transverse width w (diameter) of the illustrated substantially circular bore B, and a minimum wall thickness t' slightly more than 0.6 w. An MD of about 10 mm would suggest a bore diameter of about 2 mm.

Figures 2, 3 and 4 all show schematically in cross-section a preferred form of article according to this invention based on a roughly square profile of polysiloxane rubber R having four depressions D of depth d formed by concave surfaces leading to convex rounded points and having a substantially circular bore B. The maximum wall thickness t is about 2.25 times the width w of the substantially circular central bore B, and τ' is approximately equal to w. A maximum transverse dimension (similar to MD of Figure ID) of about 10 mm would indicate a transverse bore width (diameter) w of about 1.8 mm. A larger bore B' indicated by the broken line, having w of about 3.6 mm and corresponding by thinner walls, may be preferred for some purposes where lower compressive forces are desired.

A sealant, gel G, is shown in Figure 2 adhering to the concave surface of the upper and lower depressions and almost filling the depressions. When the article is compressed between compression members A, the upper points P' tend to bend downwards and the lower points P" tend to bend upwards until the surfaces of members A come into contact with the gel G to form a seal. The presence and the relative proportions and shape of the bore B permit this sealing to be brought about by lower compression forces than would be required for a corresponding solid article not having the bore B; and the resilient recovery forces generated by the bending of the points tend to maintain positive sealing pressure against the surfaces of members A.

The corresponding article of silicone rubber R in Figure 3 has the sealant gel around its entire perimeter, with the upper and lower depressions D illustrating the possibility of filling the depressions to provide a substantially flat outer gel surface, while the side depressions show the coating of gel G following the underlying concave surface more closely. The article is shown in a confining channel or groove C, and a lid L can be applied to compress the gel-coated article in a "channel-and-lid" seal with results similar to those described for Figure 2, except that the deformed points of the article may touch and form seals against the side walls of the channel as well as against its floor and the lid.

Figure 4 shows schematically the use of the preferred article in a "tongue- and-groove" sealing arrangement where a tongue member T is inserted into a deeper channel or groove C to compress the sealing article. In this example, the profiled article of silicone elastomer R is enclosed in a sleeve S of polypropylene/EPDM blend (Sarlink 3140 Trade Mark) carrying the sealant gel G, as described and claimed in our aforementioned copending British application 9419035.2. In this case, the compression forces more complex, with the sleeve providing the seal and the profiled elastomer R enhancing resistance to compression set of the sleeve, as well as generating positive sealing forces against the surfaces of the tongue member T and groove C . The sleeve S is shown bridging the depressions D for the purposes of this illustration, although complete circumferential contact of the sleeve S with the enclosed profiled article may be preferred in practice.

Figure 5A shows the preferred sealing member 50, similar to that described for Figure (2, 3 or 4), in a hypothetical stepped butt joint formed by components 52 and 54. Even in such a confined sealing space, the gas-tubular form 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 ps∑ S£ (not shown) and the sleeve 60 is wrapped around the end pieces to enclose die 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 me 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.

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 per. sfi) for co-extrusion onto sleeve 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

Polysiloxane elastomer ( ) None

"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. For example, on the polysiloxane elastomer carriers, the gel tends to form a jacket surrounding the carrier surface with little or no adhesion to it, and this is satisfactory for many sealing arrangements according to the present invention. The invention thus includes the sealant material extending around the whole circumference of me article being self-coherent to an extent which secures it around the article without necessarily adhering thereto.

For such sleeve sealant carriers, and when the article of this invention is itself the sealant carrier, the relative thicknesses of the 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. 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 maximum transverse dimension. The profiled articles having the surface depressions according to the present invention may be moulded (preferably extruded) using known materials and techniques with suitably shaped moulds or extrusion dies. The sealant coatings may be applied by known co-extrusion techniques or by separate coating of previously formed carriers. The fitting of sleeve sealant carriers over the profiles having the surface depressions of the present invention may be performed by any convenient method, preferably by extruding a tube of the sleeve material, or co-extruding a tube of the sleeve material with an outer layer of the sealant material, around a previously-formed profile having the surface depressions. The extruded tube may then be drawn down onto the profile to form the fitted sleeve, preferably with applied external pressure and/or internal vacuum, to achieve complete circumferential contact between the profile and me sleeve. Suitable equipment for performing these operations will be known to persons familiar with extrusion coating techniques.

The various features described and/or illustrated for the present invention may be used in any desired combination.

For some purposes, it may be desirable to use in combination with the triblock copolymer gel sealants a carrier (hollow or solid, of whatever shape desired) comprising a triblock copolymer similar or identical to that used in the gel. Such combinations tend to enhance the compatibility and mutual adhesion of die gel and carrier, and may improve the recyclability of the combination. The invention accordingly includes a flexible sealant article comprising a fluid-extended triblock copolymer gel carrier on a thermoplastic triblock copolymer carrier member. A preferred combination is Thermolast (Trade Mark) thermoplastic elastomer, comprising Kraton (Trade Mark) styrene-ethylene/butylene-styrene triblock copolymer having added polyphenylene oxide, wid gel made from Septon (Trade Mark) styrene-ethylene/propylene-styrene triblock copolymer extended with Fina A360B oil.

Another aspect of the present invention provides a useful variant of the earlier concept, comprising a flexible tubular article of polymeric material preferably having an internal longitudinal bore, and having at least one (preferably at least two) longitudinally-extending surface depressions carrying sealant material, preferably gel, wherein at least one sealant-carrying depression is of re-entrant form partly enclosing a surface of the sealant material facing substantially outwards from the depression. The materials, methods of manufacture and uses of the present articles may be similar to those hereinbefore described. The dimensions, however, may tend to be different, owing to the re-entrant structure, which may resemble arms of the polymeric material extending to partly encircle the sealant. In some forms, it may be advantageous if at least one re-entrant depression is deeper (in a sense substantially radial to the tubular article) than its maximum width (in a sense substantially circumferential to the tubular article.

Although the cross sectional shape, number, and position of the surface depressions is not critical, as hereinbefore mentioned, an especially useful form of the present invention has been developed having a second sealant-carrying depression substantially on the opposite side of the bore from, and facing in substantially the opposite direction to, the said re-entrant depression. In some cases, it may be preferred that the said second depression is also of re-entrant form partly enclosing a surface of the sealant material facing substantially outwards from the said second depression.

The articles according to this aspect of the invention may be especially useful when positioned within a close-fitting channel with me entrance to the or one of the re-entrant sealant-carrying depression(s) facing outwards from a longitudinally- extending opening in the channel. Articles according to this or other aspects of the invention may be useful as a component of a tongue-and-groove sealing arrangement, the tongue of which is receivable into the or one of the re-entrant sealant-carrying depressions.

Embodiments of this aspect of the invention will now be described in more detail by way of example, with reference to the accompanying drawings, wherein:-

SUBSTΓΓUT Figure 10 shows a plan view of an elongate article according to this invention;

Figure 11 shows an enlarged cross-sectional view of the article on the line A-A of Fig. 10;

Figure 12 shows a perspective view of the article shown in Fig. 10, and Figures 13 and 14 show me use of the article in a tongue-and-groove sealing arrangement before and after insertion of the tongue.

Referring to Figures 10 to 12, the article comprises an elongate body 10 of elastomeric material having a substantially circular bore 12, on diametrically opposed sides of which are surface depressions 14, 16 carrying gel sealant 18 (omitted in Fig. 12 for clarity). The surface depressions 14, 16 in this example are relatively deep slots in the body 10 and respectively have re-entrant formations ("lips") 20, 22 partly enclosing the respective outward-facing surfaces 24, 26 of e gel.

In Figure 13, the gel-carrying article 10 is positioned in a groove or channel member 30, which may be part of any relevant structure to be sealed, for example those described in the aforementioned co-pending application, and a tongue 32 is shown in position ready for insertion. In this case, the article 10 is shown having a small shoulder formation 11 to help complete the seal on insertion.

In Figure 14, the tongue member 32 has been inserted into the gel-containing groove in the article 10, thus displacing some of the gel 18 out of the lips 20, 22 and distorting the bore 12, as schematically indicated.

Claims

CLAIMS;

1. A flexible tubular article of polymeric material having an internal longitudinal (preferably substantially circular) bore whose maximum transverse width is not more than three times (preferably not more than twice, more preferably not more than 1.5 times) its minimum transverse width, and having externally at least one (preferably at least two) longitudinally extending surface depression(s) so arranged that

(a) the maximum wall thickness of the polymeric material between the internal bore and the external surface of the tubular article (preferably between the said depressions) is not more than three times (preferably not more than twice) the said maximum (preferably i nimum) bore width, and the minimum wall thickness of the same (preferably underlying the said depressions) is not less than 25% (preferably not less than 50% , more preferably not less than 75%) of the said minimum (preferably maximum) bore width, and

(b) the depth of each of the said depressions extends to at least 10% (preferably at least 20%, more preferably at least 30%) of the said maximum wall thickness.

2. An article according to claim 1, having the said surface depressions symmetrically arranged about its tubular axis.

3. An article according to claim 1 or 2, having at least three and not more than twelve (preferably not more than ten) of the said surface depressions.

4. An article according to claim 3, having four of the said surface depressions.

5. An article according to claim 3 or 4, whose transverse cross-sectional outline is substantially a 3-, 4-, or more-sided polygon with each of its sides incorporating a respective one of the said depressions, which depressions preferably occupy more than 50%, more preferably more than 70% , of their respective polygon sides.

6. An article according to claim 5, wherein the majority of each side of the said polygon outline is formed by a concave surface of the polymeric material.

7. An article according to claim 6, wherein each corner of the said polygon outline is formed by a convex surface of the polymeric material whose convex perimetric length is less than (preferably less than half) that of the adjacent concave surface(s).

8. An article according to any preceding claim, wherein at least one (preferably at least two) of the said surface depressions carries a (preferably adherent) layer of sealant material capable of forming a seal between the article and a surface against which the article carrying the sealant will be pressed in use.

9. An article according to claim 8, wherein the sealant material adheres to d e surface of the article and does not extend circumferentially beyond d e surface depression carrying it.

10. An article according to claim 8, wherein the sealant material extends circumferentially into at least two of the surface depressions, preferably extending around the whole circumference of the article.

11. An article according to claim 10, wherein the sealant material extending around me whole circumference of the article is self-coherent to an extent which secures it around d e article without necessarily adhering thereto.

12. An article according to any of claims 1 to 7, having fitted diereon a tubular sleeve of polymeric material (preferably elastomeric material) which surrounds d e article and is capable of forming a seal to a surface against which the article and die tubular member will be pressed in use.

13. An article according to claim 12, wherein the said sleeve bridges across the said surface depressions, or is in close contact with substantially the entire circumference of the article including me surface of the said depressions.

14. An article according to claim 12 or 13, wherein the said sleeve carries on at least part of its exterior surface an adherent layer of sealant material.

15. An article according to any of claims, 8 to 11 and 14, wherein me sealant material extends along substantially the whole length of the article.

16. An article according to any of claims 8 to 11, 14 and 15, wherein ie sealant material is a gel.

17. An article according to claim 16, wherein the sealant material is a thermoplastic gel, preferably a triblock copolymer gel.

18. An article according to any of claims 8 to 10 and 14 to 17, wherein an adhesion-promoting layer is provided to cause or enhance the adhesion of the sealant material to the underlying surface.

19. An article according to claim 18, wherein the adhesion-promoting layer comprises fibrous material, preferably enclosing the said article or sleeve providing the said underlying surface.

20. An article according to claim 18, wherein the adhesion-promoting layer comprises a coating of polymeric material which adheres to the sealant material and to the said underlying surface more strongly than the sealant material itself adheres to the said underlying surface.

21. An article according to any preceding claim, wherein the said polymeric material having the internal bore is at least partly composed of elastomeric material, preferably a polys iloxane-based elastomeric material.

22. An article according to any preceding claim whose maximum transverse dimension excluding any sealant layer or sleeve is not more than 20 mm, preferably not more than 15 mm; and not less than 2.0 mm, preferably not less than 3 mm, more preferably not less than 5 mm.

23. An article according to claim 22, wherein the said maximum transverse dimension is within the range from 2 to 5 mm or within the range from 5 to 10 mm or within the range from 10 to 15 mm.

24. An article according to any preceding claim, wherein the average transverse width of the said internal bore is less than 60% of the maximum transverse dimension.

25. The use of an article according to any preceding claim as a component of a ring, sandwich, channel-and-lid, or tongue-and-groove sealing arrangement, preferably with a sealant material carried by me article forming a seal against another surface of the said sealing arrangement.

26. A sealant article comprising sealant material (preferably gel) carried on a carrier member with fibrous material in contact with (preferably surrounding) the carrier member to cause or enhance adhesion of d e sealant material to the carrier.

27. A sealant article comprising a flexible tubular inner member of polymeric material (preferably elastomeric material) carrying a surrounding sleeve of polymeric (preferably elastomeric) material and a layer of sealant material (preferably gel) adhering to the outer surface of the sleeve so that the sealant material can be brought into sealing contact with a surface against which the article will be placed in use.

28. A flexible tubular article of polymeric material preferably having an internal longitudinal bore, and having at least one (preferably at least two) longitudinally-extending surface depressions carrying sealant material, preferably gel, wherein at least one sealant-carrying depression is of re¬ entrant form partly enclosing a surface of the sealant material facing substantially outwards from the depression.

29. An article according to claim 28, wherein at least one re-entrant depression is deeper (in a sense substantially radial t the tubular article) than its maximum width (in a sense substantially circumferential to the mbular article.

30. An article according to claim 28 or 29, having a second sealant-carrying depression substantially on the opposite side of the bore from, and facing in substantially the opposite direction to, d e said re-entrant depression.

31. An article according to claim 30, wherein the said second depression is also of re-entrant form partly enclosing a surface of the sealant material facing substantially outwards from the said second depression.

32. An article according to any of claims 28 to 31, positioned within a close- fitting channel with the entrance to the or one of me re-entrant sealant- carrying depression(s) facing outwards from a longitudinally-extending opening in the channel.

33. A flexible sealant article comprising a fluid-extended triblock copolymer gel carrier on a thermoplastic triblock copolymer carrier member.

34. Use of an article according to any of claims 28 to 33 as a component of a tongue-and-groove sealing arrangement, the tongue of which is receivable into the or one of the re-entrant sealant-carrying depressions.

35. An article according to any of claims 26 to 33, including any of me features of shape, material, or construction specified in any of claims 1 to 24.

36. The use of an article according to any of claims 26 to 33 in a sealing arrangement as specified in claim 25.

37. An article according to any of claims 1 to 24 and 26 to 33, wherein at least the outer surface region on which the gel is carried 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 man 40%, preferably less than 20%, by weight of aklylacrylate, or polyethylene, preferably low-density polyethylene.

38. An article according to any of claims 1 to 24 and 26 to 33, wherein at least the outer surface region on which the gel is carried is composed of, or comprises as a majority component, elastomer material, preferably thermoplastic elastomer material.

39. An article according to claim 38, wherein the elastomer material is or includes very low density polyethylene plastomer, polyether/polyester block copolymer, or a polypropylene/EPDM blend, or a diermoplastic elastomer triblock copolymer, preferably a styrene-alkylene-stryene triblock copolymer.

40. An article according to any of claims 1 to 24, 26 to 33, 35 and 37 to 39, wherein the sealant material is a thermoplastic gel having substantially elastic deformation up to an elongation of at least 100%, 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.

41. An article according to claim 40, wherein the sealant material is a gel comprising

(i) a styrene-alkylene-styrene block copolymer, preferably a styrene-

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