KR960002862B1 - Dimensionally recoverable article and the method of producing the same - Google Patents

Abstract

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Description

Products that can be restored to dimensions and their manufacturing method

1 is a perspective view of a wrap-around artcle in accordance with the present invention, which exaggerates the thickness of the composite structure for clarity.

2 is a partial cross-sectional view of the product of FIG.

FIG. 3 is an exploded cross sectional view showing a corner portion of the product shown in FIG. 1 after wrapping the product around a substrate; FIG.

4 and 5 are exploded cross-sectional views showing corner portions of a modified example of the product in FIGS. 1 to 3 after the product is wrapped around the substrate.

The present invention relates to a resilient product. A resilient product refers to a product whose dimensions can be substantially modified in the case of special treatment such as, for example, heat treatment. Normally, these products are restored to their original shape in a deformed state when heat is applied. However, as used herein, the term "heat-recoverable" is used when heat is applied even if it is not deformed in the first place. Products that can take on new forms are also used in the sense of inclusion.

In its most common form, these products include heat shrinkable sleeves made of polymeric materials having elastic or plastic memory properties, such as those described in US Pat. Nos. 2,027,962, 3,086,242, and 3,597,372. As clearly described in US Pat. No. 2,027,962, the original dimensionally heatstable product may be a temporary form in a continuous process, in which, for example, a compressed tube is heated. As it expands in a dimensionally heat-stable form, in other cases, a preformed product that is dimensionally heat-stable is transformed into a dimensionally heat-stable form through individual steps.

In producing such heat recoverable products, the polymeric material may be cross-linked at any stage in the manufacture of the product to increase the required dimensional restoreability. One method of making a heat recoverable product is to form a polymeric material into a desired thermally stable form, to crosslink the polymeric material, and to make the product above a crystalline melting point, Or, in the case of an amorphous material, heating above the softening point of the polymer and cooling the product to deform the product to keep the product deformed. In use, the product in its deformed state is thermally unstable, so when heated it returns to its original thermally stable form. Another method involves deforming the substantially noncrosslinked polymer at a temperature below the crystal melting or softening point of the material, and melting at least one hollow portion by melting together some or several portions of the material and at least one other polymer component. Forming a thermally resilient article in form and crosslinking the substantially noncrosslinked material.

In other types of products, the elastomeric member is attached to the second member in an elongated state, which is weakened when heated, thereby enabling restoration of the elastic member. This type of thermally resilient article is described, for example, in British Patent No. 1,440,524, in which an external tubular elastomeric member is attached to an internal tubular member in an elongated state.

Thermally resilient products have been particularly used for the protection of elongated substrates such as, for example, splices of communication cables.

In addition to forming an environmental seal, the sleeve must be made to withstand internal pressure, for example when the sealing of the connection is complete, for example for leakage testing in accordance with the bell cycle and the UK Telte body standard. This is because a significant internal pressure may be generated due to the pressure applied or the temperature generated during the operation. Known heat-resilient sleeves are well suited for sealing dispensing connections, but many large communication cables are pressurized to remove moisture and fabricated with thicker walls to withstand these pressures for extended periods of time. This is more demanding and expensive, and requires a high level of skill in field installation.

U.S. Patent No. 3,669,157 to Carolina Narrow Fabric and Japanese Patent No. 53-13805 to Matsushita disclose thermally shrinkable tubular textile products that may be impregnated with any thermosetting resin. . However, the products disclosed in these patents have been found to be very difficult to install because the resin is displaced during restoration and the fabric is ruptured by the resin or the resin is separated from the fabric. Therefore, these existing products are limited in their usefulness and require high technology for use in most communication facilities.

The present invention provides a product that can improve its resistance to resilience and maintain its integrity to form an effective ambient seal and, if necessary, a pressure retaining seal under appropriate circumstances as described herein.

One aspect of the invention includes a composite of a heat recoverable fabric and a polymeric matrix fabric, wherein (a) the heat recoverable fabric comprises fibers that are restored upon heating, wherein the fibers are at least 5 at temperatures above their recovery temperature. Having a restoring stress (Y) of x 10 ^-1 MPa, and (b) the polymeric matrix material has a break elongation of at least 20% and a strain rate of 300% per minute at or above the fiber recovery temperature. It has a 20% secant modulus (X) of at least 10 ⁻² MPa, and at this temperature the following inequality (1):

Where R is the elongation / temperature relationship that satisfies the mean effective volume fraction of the heat-resilient fibers of the composite along a given direction based on the total volume or the appropriate portion of the composite structure. Provides thermally resilient products.

The present invention also provides a method for producing a dimensional heat recoverable article comprising a composite structure that is restorable by a restorable fibrous component, the method comprising the steps of defining a heat recoverable fabric as defined above. Binding to a polymeric matrix material as such.

The term "fiber" in the present invention includes filaments, for example monofilaments or multifilaments or includes staple fibers, wires and tapes. It is preferable to use filaments, in particular, heat-resilient fibers in the form of monofilaments, as the fabrics used in the articles of the invention.

The heat recoverable fiber used in the product of the present invention preferably has a minimum restoring force of 10 ⁻¹ MPa at a temperature above the transition temperature of the fiber, more preferably a minimum restoring stress of 5 × 10 ⁻¹ MPa, and usually Has a minimum recovery stress of at least 1 MPa. Theoretically, there is no upper limit of the restoring stress, but in practice, the highest value normally obtained from polymeric fibers is 200 MPa, and usually 100 MPa.

The fiber may be formed of a polymeric material capable of heat recovery. By "restore temperature" of a heat recoverable polymeric material is meant the temperature at which the restoration of the polymeric material is substantially completed. In general, the recovery temperature is the melting temperature of the crystal when the polymer is crystalline, and the glass transition temperature when the polymer is amorphous.

In most forms of the product according to the invention, since the polymeric matrix softens below the recovery temperature of the heat recoverable fibers, the matrix material has the required elongation and secant coefficient, and the temperature at which inequality (1) is satisfied. (T) will be equal to the recovery temperature of the fiber. However, the present invention also includes the case where the rigid matrix material is softened to allow the fiber to be recovered by allowing the fiber to withstand the recovery over a temperature range above the recovery temperature of the fiber.

The heat recoverable fiber may be formed of a polymeric material having good physical properties and in particular good creep resistance to the fiber. Olefin polymers such as polyethylene and ethylene copolymers, polyamides, polyesters, acrylic polymers and other polymers may be used, as long as they are crosslinkable. Particularly preferred polymeric materials of the fibers have a density of 0.94 to 0.97 / g㎳ / ㏄, a weight average molecular weight (Mw) of 80 × 10³ to 200 × 10³, and a number average molecular weight (Mn) of 15 × 10³ to 30 × 10³ Based on phosphorus polyethylene.

The recovery temperature of the fibers is preferably 60 ° C. or higher, most preferably 80 ° C. to 250 ° C., for example 120-150 ° C.

When the fibers are crosslinked by irradiation, it is convenient to integrate this crosslinking step into the fabrication process. The fibers can be drawn below their melting temperature and preferably drawn up to 800-2000% and then irradiated to effect crosslinking. In the preparation of the fibers, a slightly less favorable method is a method of drawing and irradiating the fibers to crosslink them, preferably heating the fibers to above their melting temperature, stretching the fibers, and then cooling the stretched fibers. to be. The high density polyethylene fibers are irradiated with from about 4 to about 30 megarads, preferably from about 14 to about 25 megarads, in particular from about 7 to about 18 megarads, more particularly from about 10 to about 18 megarads. . Usually the gel content of the crosslinked fibers is at least 20%, preferably at least 30%, and at most 40%. In practice, a gel content of more than 90% is not easily obtained. The fibers thus produced may have high strength even after restoration. Other advantages of fiber irradiation will be described below with regard to lamination.

The resilient fabric may, if desired, be made of only the above heat recoverable fibers, or may comprise other fibers other than the heat recoverable fibers. If the fabric comprises other fibers, R in formula (1) relates only to the heat recoverable fiber component. The woven fabric may be made into knit, woven, nonwoven, braided or the like in other forms. This resilient fiber may form part of the fabric in its manufactured form, or may be added or inserted after manufacture of the base fabric. In a preferred embodiment, the fabric is in fabricated form. Woven fabrics may comprise only heat recoverable fibers, or may include non-heat recoverable fibers or filaments with heat recoverable fibers. The fabric may be, for example, twill, broken twill, satin, cotton, satin, leno, plain, hop sack, and sack. And one-ply or several-ply weaving, for example two- or three-ply weaving, in the form of variously woven combinations. Since the fabric is a woven fabric with heat-resilient fibers in one direction and dimensionally heat stable fibers in the other direction, the fabric can only be restored in one direction throughout the fabric, and generally described below. will be. However, the described features can be applied to other fabrics.

This fabric may optionally be knitted and, if desired, may be knitted into warp knits or weft knits. If this fabric is made only of heat-resilient fibers, it will be restored in two directions, but preferably, as in knitted fabrics, if the fabric is knitted into a heat stable fiber and the heat-resilient fibers are inserted in the direction of the string or the line, This fabric will only be restored in one direction.

If inserted in any given direction, this fabric will only be restored in one direction.

The average effective volume fraction of the heat recoverable fibers in the composite structure along any given direction is determined first of all by the size of the fibers, the type of weaving or knitting used, and the direction considered. The average effective volume fraction (R) used in the inequality (1) is the vector component of the fiber in a given direction divided by the total cross-sectional area of the composite structure taken on a plane perpendicular to the direction considered for the cross-sectional area of each thermally resilient fiber. The sum of the multiplied values is defined as the average value averaged along the considered direction. Thus, if the thermally resilient fiber lies at an angle of α with respect to the considered direction, the product of the cross-sectional area of the fiber and the component in the considered direction is given as the fiber area xcosα. According to the plane perpendicular to the considered direction divided by the total area of the composite structure, the sum of these values for all cut fibers is given by the R value at any particular point in the considered direction, and in any suitable fabric in the considered direction. The average value of R over the entire length of the site is used in the inequality (1) above.

In the case of weaving in which all of the heat-resilient fibers are parallel (in the case of weaving or in the direction of the string or in the case of weaving) and the direction considered is parallel to the restorative fibers (ie, the restoring direction), the average value of R It is obtained by dividing the total cross sectional area by the total cross sectional area of the composite structure.

The heat recoverable fabric is preferably bonded to or embedded in the polymeric matrix material. The advantages of the above investigations are relevant here. If the fibers are irradiated before or after the fabric is formed (particularly in an oxygen atmosphere), chemical changes occur on the surface that will significantly improve the adhesion of the matrix material. At or above the recovery temperature of the fiber, the polymeric matrix material should be restricted in flow under pressure to maintain the integrity of the composite structure without substantially impeding the restoration of the fiber. Preferably, the polymeric matrix material is preferably measured by measuring at least 50% elongation at break, very preferably at least 100% elongation at break, in particular at 400-700% at break and 300% strain per minute at the above-mentioned temperatures. It has a 20% secant coefficient of at least 5 × 10 ⁻² MPa, very preferably at least 10 ⁻¹ MPa.

The properties of the polymeric matrix material need not necessarily be applied after restoration, although it is desirable for the product to be flexible even at room temperature. Thus, for example, the polymeric matrix material may be cured to a thermosetting state upon heating, provided that the curing rate is low enough under restorative conditions so as not to adversely affect the above-described physical properties of the polymeric matrix material during fiber restoration. . Thus, for example, the polymer constituting the matrix material may comprise a group of grafted hydrolyzable silanes capable of crosslinking the material under moisture. Alternatively, the matrix material may comprise a polymer, preferably a rubber, in particular an acrylic rubber containing an epoxy group and a room temperature insoluble curing agent, for example dicyandiamide.

The polymeric matrix material may be thermoplastic or elastomeric. In general, the polymeric matrix material and the material of the resilient fiber must be chemically or physically miscible, preferably both chemically and physically. This means that they should have similar or identical chemical structures, and that their proper physical properties should be similar or identical during lamination, installation and use, in particular the matrix and fibers, respectively, of low density polyethylene and high density Polypropylene may be sufficient. Other pairs of miscible polymers are skilled. Thermoplastic materials suitable as matrix materials are, for example, polyethylene, polypropylene, polybutylene, polyesters, polyamides including ethylene-vinyl acetate copolymers, ethylene / ethyl acrylate copolymers, linear low density and high density grades. , Polyetheramide, perfluoroethylene / ethylene copolymer, polyvinylidene fluoride and the like. Secondary materials of this material include acrylonitrile butadiene styrene block copolymers, acrylic elastomers including acrylates and methacrylates, and for example, copolymers of polybutyl acrylate and poly 2-ethylhexyl acrylate, ethylene High vinyl acetate copolymers (VAE'S), polynorbornene, polyurethanes and silicone elastomers and the like. The polymeric material constituting the matrix may be transparent (at least in visible light), or may be completely opaque, or may have opacity between these two extreme states. For example, when opacity is increased, the time required for restoration can be reduced by mixing a small amount of carbon black, such as up to 5% by weight, of carbon black in the matrix. In addition, the resistance of the material to thermal damage, in particular flame and ultraviolet damage, is reduced. The matrix material (or part thereof) may be crosslinked by irradiation, or if the physical properties of the matrix at the recovery temperature are the same as defined after the crosslinking step, for example chemical crosslinking with a peroxide crosslinker It can be crosslinked by other means as well. When using irradiation, the radiation dose of 10 megarad or less is good, especially the radiation dose of 3-7 megarad. The extent of crosslinking should be such that the matrax can be restored with the fabric, and also the matrix can be circulated or restored during heat recovery, especially during heat recovery by the torch, and also during the heat recovery The matrix should be prevented from flowing or dripping during heat recovery. The recovery rate of the composite structure after irradiation should be at least 50%, especially at least 70% compared to before irradiation. These dosages can be considered typical for olefinic polymers such as polyethylene. The skilled person will be able to select a suitable dosage depending on the different concentrations of the prorads. Composite structures may be produced using only a single irradiation step, provided that the matrix and fiber beam reactions are compatible. The beam reaction of the oriented fibers may be increased by the addition of prorad, and in the case of less oriented matrices, the response may be reduced by adding antirad. If not, a separate crosslinking process would be fine. Another feature after lamination crosslinking (especially by irradiation) may be formed between the restoring fibers and / or any other fibrous tissue that allows to maintain its structure as a composite itself under particularly severe repair conditions. Is that there is. This eliminates the need for physical interlocking, making the stacking process even less difficult.

It is preferred that the heat recoverable fabric be bonded to the polymeric matrix material, which may be adhesive, ie by chemical or physical surface interactions, or optionally by mechanical interlocking. have.

Most preferably, the heat recoverable fabric is embedded in the polymeric matrix material to form a composite structure. The term "burying" herein means that the polymeric matrix material surrounds at least a major part of the surface area of the fibers constituting the fabric.

The fabric is preferably completely surrounded by a polymeric matrix material. However, it is also possible to have the polymeric matrix material generally enclose less than the total fiber area, which is sometimes desirable. An example of this is when the fiber-matrix adhesion takes place. When sufficient area of the fiber is bonded or interlocked to the polymeric matrix material, it forms a composite structure that can maintain its integral structure during the restoration of the product. For the avoidance of doubt, the term matrix here also includes materials that surround (partially or entirely) the fibers, as well as materials that simply adhere to the surface of the fabric but do not penetrate the gaps of the fabric. Used.

The polymeric matrix material on at least the surface of the composite to be subjected to heat should be substantially unstressed and also have a thickness of at least 0.03 mm, in particular at least 0.01 mm, in particular at least 0.2 mm, more particularly 0.2-2 mm may be sufficient. This is described in British Patent Application 8300217, which increases the performance of composite structures that are thermally restored using conventional propane torches.

In the composite structure, the ratio of the volume occupied by the heat-resilient fibers of the fabric to the total volume of the composite structure is at least 0.01: 1, preferably about 0.1: 1 to about 0.8: 1, most preferably 0.2: 1 To 0.4: 1.

In composite structures, the volume of heat recoverable fibers in any given unit volume of the composite depends on the fiber strength, the polymeric matrix strength, and the integrity of the fiber / polymeric matrix structure at restorative conditions. When the following inequality (1) is satisfied, it was found that an acceptable resilient product was formed.

Where X is the 20% secant coefficient of the polymeric matrix material and Y is the restoring stress of the fiber, both values at temperatures above the restoring temperature of the fiber. And R is the average effective body integration ratio of the heat recoverable fibers in the composite structure.

The value of is better than less than 0.5, and less than 0.05 is best.

Composite structures can be made, for example, by laminating one or more impacts of a polymeric matrix material on a heat recoverable fabric. Preferably sufficient heat and pressure are applied to result in adhesion to the polymeric matrix material of at least the major part of the fabric or a significant amount of mechanical interlocking occurs. As a result, applying heat results in a composite structure that is restored as a single body.

Other methods of adhering the matrix material to the fabric include, for example, using acrylic prepolymers activated by impregnation, solution coating, slurry coating, powder coating, reactive prepolymers such as UV or peroxides, and the like. Method and the like. Either way, if the restoration of the fabric is not adequately suppressed, it should not be heated to such an extent that the fabric is too heavily restored.

Thermally resilient products can be used for several purposes. It is particularly suitable for enclosing elongated substrates of pipes, conduits, cables or the like. The heat recoverable article may coat a layer of sealant or adhesive on its surface. The sealant may be a frankincense resin, and the adhesive may be a thermally active adhesive such as a hot melt adhesive. Hot melt adhesives include adhesives based on polyamide and ethylene vinyl acetate copolymers. Such adhesives are well known and are shown, for example, in US Pat. Nos. 4,018,733 and 4,181,775. If desired, a thermosetting adhesive may be used, for example as described in British Patent No. 2104800.

Proper selection of the polymeric matrix material allows the polymeric matrix material to act as an adhesive, thereby allowing the restored composite structure to be secured to the substrate in a sealed state. The fabric may be embedded in one or more polymeric matrix materials to provide the required properties. For applications surrounding elongated substrates, the fabric may be laminated on both surfaces in layers of matrix material, the inner surface being in use is laminated with an adhesive polymeric matrix material and the outer surface being It can be laminated with a non-adhesive polymeric matrix material. As will be readily appreciated, the matrix material may be selected according to various additives such as antioxidants, UV stabilizers, pigments, anti-tracking agents and the like, or other various desirable properties inherent in the matrix material itself.

The thermally resilient article of the invention is typically in the form of a sheet, but may take any other form, such as tubular, for example, where one cable is connected to two or more other cables, or two or more pipes It may include a break-out structure for cable connection when coupled to each other and a plurality of tubular portions connected to each other.

The heat recoverable sheet according to the invention can be used to form a cable connection case, a pipe segment or a pressure chamber as described in British Patent Application 8300221. Thermally resilient products according to the invention have been found to be particularly suitable for enclosing the connections between subscribing communication cables. The restored product is particularly resistant to the effects of pressure, and its preferred implementations are impermeable, with sufficient resistance to rupture under a pressure of about 70 kPa at the operating temperature of such a system (a pressure commonly used in pressurized communication systems). Hoop strength.

When forming the casing of the cable connecting portion, the sheet of the present invention is used in combination with the inclined end portion and the inner support of the same kind as the cylindrical liner. This liner may be shaped in such a way that its larger center part is snug around the bulky cable connection and the inclined end receives the transition to the cable. The liner may be constructed in a wrap around, in which case it may comprise a half-shell with a crown or other end support, or may be wound around the cable connection and the crown end may be over the cable. It includes a sheet of rigid material that provides an end support that can be wound downward. In this way, the pressure chamber is formed around an object, such as a cable connection, the sheet material is impervious and provides a periphery with creep resistance and burst resistance, and the liner provides impact resistance, axial strength and other mechanical requirements. Done.

In addition to the pressure test for its integrity before use, any other feature may be provided if the pressure is to be maintained in the junction case or pressure chamber during use. It would be advantageous to install a valve at the point of receiving the other pressure in the restorable sheet, which may also be attached to the inner liner. Fabric-based sheets are suitable for installing valves or other means that must penetrate the sheet because no rupture occurs. Even if some fabrics rupture when the valve is inserted, the damage must not spread, and with caution the valve holes can be made simply by moving adjacent fibers away from each other.

The second preferred feature of the pressurized connection case is a device which prevents any coupling between the external sleeve and the cable from creating a gap by the internal pressure. One side is satisfactory with the use of a strip-like material that is bonded (preferably bonded) to the cable, the other to the sleeve (preferably bonded), and these two sides are stretchable. The result was obtained. This strip-shaped material preferably has a U- or V-shaped cross section, and is provided on the recessed surface facing the connection case. Other uses of composite structures include applications such as protection, repair or insulation from a wide range of substrates in telecommunications, high voltage, electronics, oil and gas and the manufacturing industry. For example, the cable jacket can be repaired by installing a new composite structure as well as the fabrication of the cable connection case, and in particular, advantages such as high strength, solubility and wear resistance can be obtained. It is also possible to protect pipes and the like from corrosion and other damage factors, in which case it is preferable to coat the sealant, in particular frankincense resin, on the composite structure. Insulation of the pipe may optionally be achieved by using a composite structure having some other insulation with the same foam material. Thermal and / or electrical insulation may also be provided.

Another use of this composite structure is to produce hollow products for accommodating and protecting various components.

Another use of this composite structure is to fasten two or more products, such as pipes or cables, together on a long substrate. If the pipe or cable is to be held under adverse conditions, it must be fixed to some extent and resistant to the surroundings.

One major specific example of this urethra is the protection of wires extending along the outer surface of the helicopter rotor blade blades (blade SPAR). In some cases, it may be necessary to extend this wire along the outer surface of the rotor blade blades before the wire passes through the braid. For example, such wiring is used to supply power for heating elements installed along the braid leading edge to prevent freezing of the braid. In this case, by restoring the heat recoverable product according to the present invention on the wiring, the wiring can be fixed along the surface of the blade. It has been found to be particularly suitable in this case because of its relatively high wear resistance that it can prevent or reduce any damage which may be caused by exposure to this heating element of textile restorative articles. In addition, the relatively high pressure exerted on the substrate by the mounted thermally resilient product prevents or reduces the movement of the electrical wiring caused by its centrifugal force or any other force when the braid is actuated. In addition, textile products have a relatively high burst strength, allowing restoration to occur in protrusions such as nuts and bolts on the wings.

The helicopter rotor braid is supported by vanes whose one end is attached to the gearbox of the rotor braid. To prevent freezing of the braid, a plurality of heating pads may be installed along the length of the leading edge of the rotor bridging, and power is transferred along the wiring equipment to the heating pad. In order to fix this wiring harness on the vane, a heat shrinkable wrap around composite structure is restored on the part of the vane on which the wiring is extended. The composite structure is preferably formed of a laminated heat-shrinkable fabric in which the layers of the laminated polymer are not irradiated, and the recovery rate of the composite structure is about 2: 1. Of course, these laminated layers may be irradiated and the recovery rate may vary. The cover is preferably formed of a wrap around type product, and a rail and channel type sealing device is installed. On the underside of this cover is an adhesive based on ethylene / vinyl acetate copolymer, or polyamide based, for example, to fix it to the wing and to prevent water from penetrating along the wiring harness. You may form a hot melt adhesive layer, such as these. Depending on the use of this cover, it may be desirable to coat the adhesive over its entire surface, or it may be desirable to cover only the peripheral portion extending along its edge.

In many applications, the restorative composite structure of the present invention may be made in an open form as opposed to a tubular form. The sheet form is easy to mount because it is easy to manufacture and does not require the free end of the substrate to be enclosed. However, the problem is how to fix this sheet in the form wound around the substrate. This requires some device to allow the restoring fibers on the opposite edges of the sleeve to hang over each other. The solution can be thought of in four forms. First, in order to prevent the peel-back of the overlapping edges generated during restoration, optionally additional pieces may be used to overlap or otherwise bond between the opposite edges of the sheet. Adhesion here is generally done between the matrices of opposing edge portions, so that the restoring force of the fiber must be reliably transferred from the fabric to the matrix of its edges. Secondly, any device that penetrates the sheet can be used, where the fabric is directly involved. In general, this technique is not possible with continuous sheet-like materials due to rupture problems. However, in materials made of fabrics, the bursting resistance can be extremely high. Examples of such sealing forms include the use of pre-inserted clasps such as sutures, stapling, riveting, pressure studs, and the use of any device having a plurality of protrusions located adjacent to the connection of the sheet and penetrating both thicknesses of the sheet. do. This second form will be explained more generally below. The third form involves forming or standing opposite edges of the sheet such that the opposite edge portions of the sheet can be fixed to each other by some form of clamping means, such as a channel of C-shaped cross section, or by a reusable tool. This involves adhering a certain material to the edge or forming or standing the edge. This can be done by adhering any material to the corner portions or by folding the corner portions back to one another (optionally around the rod in the longitudinal direction of the sheet). The edges of the sleeve then result in a shape similar to the classical rail and channel sealed rail disclosed in British Patent 1155470.

The fourth technique consists in forming the fabric in the form of double rewind without terminating at opposite edges to which the restoring fibers are bonded. As an example, a resilient weft on a shuttle loom may be used to insert a seal into the weaving at each corner, or any special shaped edge may be employed. Another possible method is to weave a sealed bag at each corner or squeeze the tubular structure and flatten it, and use this flattened tube as a sheet into which a sealing rod or other member can be inserted. There is this. Although this idea is mentioned only for weaving, it is applicable to other fabrics such as knitting and weaving.

Various sealing techniques described above are described in British patent application 8300223.

When the restorable sheet of the present invention is used in the form of wrap around, it would be desirable to form one flap under the two opposing edges that meet each other. Such flaps can improve ambient sealing and even pressure retention if necessary.

The second technique of keeping the sheet wrapped around will be described in more general terms. The ability of the resilient composite structure to penetrate allows some of them to be joined together to form a tubular sphere, as well as to form hollow products of various shapes such as curved or T-shaped pipes, and also to diverge simple cylindrical products. It allows you to form. Thus, in general, two or more portions of the composite structure may be joined to each other by a mechanical coupling device through the fabric. This coupling device is preferably one or more sutures or one or more staples. Sites that are bonded to each other may be separate or may simply be individual sites of a single component of the composite material. When using sutures, each suture preferably has 300-800 stitches per meter, preferably the suture line closest to the edge of the fabric is at least four rows of fiber away from that edge, with high flotation In the case of highly buoyant fabrics such as satin, in which the site is perpendicular to the bond line, a spacing of at least six lines is preferred. This corresponds to overlap edges of at least 8-10 mm, in the case of woven fabrics, at least 16 or 20 mm. Of course, hem can be provided, but this will increase the thickness of the fabric, which is generally undesirable. In order to reduce the judging of heat recoverable fibers by sewing or sewing (or stapling), the needles (or staples) must be very sharp at their ends and have a maximum diameter equal to the distance between the heat shrinkable fibers of the fabric. Should have

The advantages of sutures and stapling are: When the fiber shrinks and recovers in the axial direction, its diameter or titer increases. As a result, the voids in the fabric through which sutures or staples pass are sealed, and the fabric tightens the sutures or staples to increase the strength of the bond. Reducing the size of these voids also reduces the likelihood of fluid leakage through the restored product, as any adhesive layer or matrix material will help to fill the voids completely, for example, cable connections. Particularly useful for products used for sealing the casing or for corrosion protection of pipes or for insulation of pipes.

Typically, the composite structure needs to comprise a single fabric embedded in or adhered to the matrix polymer. However, it is possible for this composite structure to comprise two fabrics with one matrix polymer layer on a plurality of fabrics, for example between two fabrics and optionally on one or more outwardly facing surfaces. And in some cases this may be desirable. Products using one or more fabrics are useful if they have a high internal pressure to surround the substrate or if the product can be subjected to particularly severe mechanical abuse.

The invention will be described in detail according to the accompanying drawings.

1 shows a perspective view of a product according to the invention in the form of a wrap around suitable for enclosing a long substrate, such as a connection of a communication cable. This product is formed from a composite sheet 1 comprising a fabric having a heat shrinkable filament 3 in the helical direction and a multifilament glass yarn 4 in the striated direction.

As shown in FIG. 2, the fabric is completely embedded in the polymeric matrix material 5. The polymeric matrix material 5 comprises two laminates 6, 7 formed from thermoplastic polymers, each laminate being laminated on both sides of the fabric, for example by a meltlaminate process, and then All of the laminates 6 and 7 are bonded to the fabric and also crosslinked to allow the other laminate to adhere to each other and to exhibit desirable flow characteristics under selected recovery conditions. When this composite sheet is formed, rails are formed along each edge extending in the direction of the string, which acts as a means of holding these edges together after the product is wrapped around the substrate. Before or after the rail is formed in the product, the composite sheet 1 is formed with a sealant such as a frankincense resin or a hot melt adhesive or a layer 10 of an adhesive, for example. The product was found to have significant advantages over existing products. For example, this product has higher resistance to hoop stress caused by internal pressure. It is also less likely to be damaged, even if it is thermally contracted by the torch, and is more wear resistant and has a higher burst resistance.

3 is an enlarged exploded cross-sectional view showing the sealing rail of the product after the product is wrapped around the substrate. Each rail surrounds the edge of the composite sheet around a rod 12 formed of a high melting point material, such as nylon, and faces 13, 14 or its edges to form a wall between the remainder of the sheet of rod 12. The portions are formed by pressing each other, making the edge portions as shown, and heating the edge portions so that partial restoration of the fibers in the wall can occur. As shown, at one of the corners the composite sheet is folded back on itself, while at the other corner the sheet extends past the rail to form a bottom sealing flap. After the sheet is enclosed around the substrate, the two corners are joined until they come into contact with each other. For example, a metal channel as shown in British Patent No. 1,155,470 is slid over a rail and the corners are connected to each other. The product is then restored.

4 shows a variant of the product shown in FIGS. 1 to 3, wherein the composite sheet is folded back along each corner and a separate polymer seal 15 having a sealant layer 16 is provided. It is provided. The sealing member may be made of rubber or other elastomer, polyethylene or the like. 5 shows another variant of the product, wherein the sealing member 15 is adhered to any one of the corners during manufacture.

Example 1

The high density polyethylene monofilament was woven into various woven fabrics to produce a heat recoverable fabric suitable for use in the heat recoverable article of the present invention. The fabric was irradiated with air at a dose rate of 0.24 Mrads / min using 6 MeV electrons in air. The properties of these fabrics and fibers are reported in Tables 1 and 2.

TABLE 1

* Value obtained by refluxing in xylene.

TABLE 2

Fabric Properties

* Expressed as warp density per inch / weft density per inch

** Value at 10 Mrads

Polyester A = 1000 denier polyester, melting point 220 degrees Celsius

Polyester A = 840 denier polyester, melting point 220 degrees Celsius

Example 2

A restorable composite sheet, wherein the polymeric matrix material in the form of a 0.5 mm thick extruded sheet barely irradiated a 60/10 (23.6 / 3.9 cm) twill fabric woven from the same polyethylene monofilament as the fibers in the above examples. By laminating in a thermally recoverable composite sheet was prepared. This lamination process was carried out by applying pressure between the silicone rubber sheets under conditions suitable for the particular polymeric matrix material used. The lamination conditions are shown in Table 3.

TABLE 3

The composite structure thus obtained was irradiated with 6 MeV electrons at room temperature in air at a dose rate of 0.24 Mrads / min for a sufficient time until the radiation dose of 2,4 or 6 Mrads for each sample. The properties of this polymeric matrix material are shown in Table 4 and the percent recovery of the composite structure is shown in Table V. In Table 5, fabric 11 of Example 1 and the polymeric matrix of Table 4 were laminated and irradiated with an absorbed dose of 4 Mrads to prepare a composite structure. The recovery rate of the composite structure may be at least 40% of the recovery rate of the free fabric, more preferably at least 65%, and particularly preferably 70% or more.

TABLE 4

TABLE 5

Example 3

Fabrics were formed using 8-axis satin weaves with high density polyethylene filaments of 0.29 mm diameter and lined with 75E.C.G.glass fiber yarns. The density of the fabric (inclined density / weft density) was 90/16 and 35.4 / 6.3 as the number of fibers / inch and the number of fibers / cm, respectively. The fabric was irradiated with 1.5 MeV electrons at a radiation dose of 15Mards, giving the fibers a 37.3% gel value (value from reflux in xylene) and a 100% secant coefficient of 0.60 MPa at 150 ° C. The fabric was then extruded with low density polyethylene between a metal roller and a rubber roller cooled at a melting temperature of 260 ° C. Polyethylene had a thickness of 0.6 mm on one side of the fabric and 0.3 mm on the other side. After lamination, the composite structure was irradiated with high energy electrons at a radiation dose of 4 Mrads. The melt flow index of the high density polyethylene used was 3.0, the number average molecular weight was 14,800, and the weight average molecular weight was 114,800. After the secondary irradiation, the properties of the low density polyethylene laminate constituting the matrix material are as follows.

100% secant coefficient at 60 ℃ 4.8 MPa

100% secant coefficient at 150 ° C 0.03 MPa

Tensile Strength at 150 ℃ 0.13MPa

670% elongation at break at 150 ° C

Gel content (reflux in xylene) 39.2%

Viscosity 2.79 × 10 ⁵ poise at 150 ° C and 1.0rad 5 ^-1

The properties of high density polyethylene fibers irradiated at a radiation dose of 20 Mrads are as follows.

100% secant coefficient at 150 ° C 0.29 MPa

Tensile Strength at 150 ° C 2.18 MPa

780% elongation at break at 150 ° C

Gel content (reflux in xylene) 42.25%

Resiliency 0.62 MPa

87% recovery

The specimen of the sheet thus formed was cut to a size of 30 inches (12 cm) in the direction of fifteen inches (6 cm) in the file direction, and then folded opposite edges parallel to the direction of the file along a 3.5 mm diameter nylon rod. After pressing the seal to the required shape, it was heated to cause partial restoration of the fabric to form a seal as shown in FIG. Prior to forming this sealing device, a 0.4 mm thick polyamide adhesive layer such as that shown in US Pat. No. 4,018,733 or 4,181,775 was applied to the surface of a 0.6 mm thick polyethylene layer by a hot melt coating technique.

The wrap around product thus produced had a 4: 1 (ie 75%) recovery in the direction of the wire.

The product was tested by forming a branch that separates a communication cable covered with a 43 mm diameter polyethylene jacket into two cables covered with a 19 mm diameter polyethylene jacket. Raycam's XAGA (R) aluminum liner with collapsible crown end was installed over this fork so that the diameter of the central cylindrical portion was 92 mm. The product was then wound around the cable and liner and restored by heating with propane torch. The product was sealed in a conventional manner to prevent leakage of pressurized gas between the product and the cable jacket, and clips such as those presented in Nolf US Pat. No. 4,298,415 were used to seal the branch of the branching area. The cable was pressurized to an internal gauge pressure of 15 psi and subjected to temperature cycle testing on the branch, where the temperature change in each cycle was first increased from 23 ° C. to 60 ° C. for at least one hour and then 60 ° C. for four hours. After maintaining, the mixture was cooled to -30 ° C from 60 ° C for at least 2 hours, maintained at -30 ° C for 4 hours, and then the ambient temperature was increased to 23 ° C for at least one hour. No leakage occurs during 10 cycles.

Example 4

Example 3 was repeated, but in this example, the weft density of the fabric used was 18 fibers per inch (7.1 fibers per cm), and the recovery rate of the composite fabric was 3.7: 1 (ie 73%).

Example 5

Example 3 was repeated, but in this example, the raw fibers were changed from ECG 75 glass fibers to ECG 150 glass fibers, and the density of the fabric was 90/18 (30.5 / 6.3 cm), which was measured in the direction of 4: 4: A restoration of 1 is shown.

Example 6

Example 3 was repeated, but in this example a multifilament formed from aromatic polyamide filaments sold under the trade name Kevlar by Du Pont was used in place of the glass fibers used earlier. This product was substantially the same as in Example 3, but had a fairly high value with a burst value of 150 N (measured according to British standards).

Comparative Example 1

Heat-shrinkable woven fabrics using standard b-stage epoxy resin matrix polymers were prepared as comparative examples. The epoxy resin consisted of the following composition.

Component weight part

Epoxy Resin (Epoxy No. 475): Shell Chemicals sold under the trade name EPON 1001 70

Epoxy Graft Acrylic Rubber Modifiers * 1 30

Anchor 1699 (TM) -Azelaic Dihydrazide 9.8

Imidazole (accelerator) 1

(Note 1): An acrylic elastomer (acid value 3000) sold by DuPont under the trade name "Vamac" to obtain 11 epoxy groups per acid group was combined with a bisphenolol-A epoxy resin sold under the trade name "Epikote 1001". Manufactured

Each component was dissolved in methyl ethyl ketone to give a solution with 20% solids content. This solution was applied several times to a twill 2 × 2 woven fabric having a density of 60/12 (23.6 / 4.7: cm) with a glass fiber of ECG 150 in the direction of the string of unirradiated high density polyethylene fibers 0.35 mm in diameter in the helical direction. The application was made to produce a composite fabric having a thickness of 0.75 mm. This composite fabric was then heated at 60 ° C. for one hour to form a b-step epoxy resin.

When heated with a torch to restore the product thus formed, the viscosity of the matrix polymer drops almost immediately to about 50 poise, and within a very short time the viscosity of the surface layer of the matrix increases to 10 ⁸ poise or more and onto the matrix material. A film formed that caused blisters and, to a certain extent, hindered the restoration of the fibers. In addition, a significant number of polyethylene fibers were lost during restoration.

Comparative Example 2

The fabric as described in Comparative Example 1 was irradiated with high energy electrons to a radiation dose of 10 Mrads. When the fabric was heated with a torch, blisters and cracks were generated in the matrix material, and numerous bubbles were generated in the matrix material. The highest recovery reported was about 2: 1 because of the influence of the cured or partially cured matrix material to retain the fiber against the restoring force.

Claims (41)

A heat recoverable article comprising a composite of a heat recoverable fabric and a polymeric matrix material, wherein (a) the heat recoverable fabric comprises fibers that are restored upon heating, wherein the fibers are 5 × 10 ⁻² MPa at temperatures above their recovery temperature Has a restoring stress Y; (b) the polymeric matrix material has a 20% secant modulus (X) of at least 10 ⁻³ MPa as measured at a break elongation of at least 20% and a strain of 30% per minute at or above the recovery temperature of the fibers; The following inequality (1) at this temperature: Wherein R is the average effective volume fraction of the heat-resilient fibers of the composite structure in a given direction based on the total volume of the composite structure or an appropriate portion thereof. The heat recoverable article according to claim 1, wherein the heat recoverable fiber has a recovery stress of 10 ⁻¹ MPa or more at a temperature above the recovery temperature. The heat recoverable article according to claim 2, wherein the heat recoverable fiber has a recovery stress of 5 × 10 ⁻¹ MPa or more at a temperature above the recovery temperature. The heat recoverable article according to claim 3, wherein the heat recoverable fiber has a recovery stress of 1 MPa or more at a temperature above the recovery temperature. The heat recoverable article of claim 1, wherein the heat recoverable fiber is formed of a crosslinked polymeric material. 6. The heat recoverable article of claim 5, wherein said heat recoverable fibers are crosslinked to have a gel content of at least 20%. The heat recoverable article of claim 6, wherein the heat recoverable fiber has a gel content of at least 40%. The heat recoverable article of claim 1, wherein the fabric comprises dimensionally heat stable fibers. 9. The heat recoverable article of claim 8, wherein the heat recoverable fibers lie in one direction and the heat stable fibers lie at an angle to the heat recoverable fibers. 10. The heat recoverable article of claim 8, wherein said dimensionally heat stable fibers comprise glass fibers. The heat recoverable article of claim 1, wherein the polymeric matrix material has a break elongation of at least 50% at or above the recovery temperature of the fiber. 12. The heat recoverable article as set forth in claim 11, wherein said polymeric matrix material has an elongation at break of at least 100% at or above the recovery temperature of said fiber. The heat recoverable article of claim 1, wherein the polymeric matrix material is crosslinked. The thermally resilient article of claim 1, wherein the polymeric matrix material surrounds a major portion or all of the surface of the fibers that make up the fabric. 15. The heat recoverable article as set forth in claim 14, wherein the fibers constituting the fabric are completely surrounded by the polymeric matrix material. The heat recoverable product according to claim 1, wherein the ratio of the volume occupied by the heat recoverable fiber to the total volume of the composite structure is at least 0.01: 1. The heat recoverable product according to claim 16, wherein said ratio is in the range of 0.01: 1 to 0.8: 1. The method of claim 1, The value of the heat resilient product is less than 0.5. The method of claim 18, The value of the heat resilient product is less than 0.05. The heat recoverable article of claim 1, wherein the article has a sealant or adhesive layer on part or all of its surface. 21. The heat recoverable article of claim 20, wherein said article has a layer of hot melt adhesive on part or all of its surface. 21. The heat recoverable product of claim 20, wherein the product has at least part of the frankincense layer. The heat recoverable article of claim 1, wherein the composite structure comprises at least two heat recoverable fabrics and a layer of polymeric matrix material disposed therebetween. The thermally resilient article of claim 1, wherein the composite structure has a tubular form. 10. The apparatus of claim 1, wherein the composite structure is open and has a pair of opposing edge portions, wherein the article further comprises a wrap around sealing device such that the corner portions retain the bond upon restoration of the article. Resilient product. 26. The heat recoverable article of claim 25, wherein said restorable fibers lie substantially parallel to each other and said opposing edge portions extend substantially perpendicular to said restorable fibers. The heat recoverable article of claim 1, wherein two or more portions of the composite structure are joined to each other by a mechanical joining device through the fabric. 28. The heat recoverable article of claim 27, wherein said portions of said composite structure are joined to each other by one or more sutures. 28. The heat recoverable article of claim 27 wherein said portions of said composite structure are joined to each other by one or more staples. 28. The heat recoverable article as set forth in claim 27, wherein said composite structure is hollow and partially or entirely secured in said hollow form by a mechanical coupling device. 31. The heat recoverable article of claim 30, wherein said hollow form is tubular. 31. The heat recoverable article of claim 30, wherein said hollow form comprises at least two hollow regions in communication with each other. 33. The product of claim 32, wherein the hollow form comprises two tubular portions. 31. The heat recoverable article as set forth in claim 30, wherein said hollow form is branched at the end of the tubular portion. A method for producing a heat recoverable article comprising a composite structure that is restorable by a restorable fiber component, which comprises: (a) restoring upon heating and restoring a stress (Y) of at least 5 × 10 ⁻² MPa at a temperature above Providing a heat recoverable fabric comprising fibers having; (b) having a 20% secant modulus (X) of 10 ⁻² MPa or more as measured at a break elongation of at least 20% and a strain of 300% per minute at or above the recovery temperature of the fiber, and wherein at this temperature the following inequality: Where R is the average effective volume fraction of the heat-resilient fibers of the composite structure in a given direction based on the total volume of the composite structure or a suitable portion thereof, the matrix of polymeric materials having an elongation / temperature relationship A method of making a heat recoverable product comprising the step of applying to the fabric as. 36. The method of claim 35, wherein the polymeric material is applied by high thermal lamination, spray application or powder application. 36. The method of claim 35, further comprising crosslinking the fibers of the fabric prior to applying the polymeric material. The method of claim 37, wherein the fiber is subjected to irradiation. 39. The method of claim 38, wherein said irradiation is carried out under an oxygen atmosphere. 38. The method of any one of claims 35 to 37, further comprising crosslinking the composite structure. 41. The method of claim 40, wherein the composite structure is subject to irradiation.