KR0178131B1 - Elongate shaped strand - Google Patents

Abstract

The present invention relates to elongate shaped strands of polymer for making heat-recoverable articles.

An object of the present invention is to provide a molded strand for producing a heat recoverable article having a high tear strength. The object is that the forming strand has at least one band, fiber, or braid of fibers or fibers of strong material at the heat deflection temperature of the molding strand, the strip or fiber (s) being 0 ° relative to the longitudinal axis of the core. It is achieved by forming an angle that is larger and smaller than 90 °. The reinforcing layer formed by the windings, twists, weavings, etc. has the advantageous property of being able to adapt to changes in the cross section of the forming strands caused by stretching or pulling.

Description

Long forming strand

The present invention relates to elongate shaped strands of polymer for making heat-recoverable articles.

In European patent application EP-A2-0115905 a heat recoverable article is known, which consists of a fabric consisting of heat recoverable fibers and non-heat recoverable fibers.

Heat recoverable fibers consist of polymers, while non-heat recoverable fibers are made of polyester or glass.

A disadvantage of the known fabrics is that because the tensile strength of the heat recoverable fibers is extremely small at shrinkage temperatures, i.e., 130-150 ° C., the fabric may tear when an excess load is applied to the fibers.

An object of the present invention is to provide a molded strand for producing a heat recoverable article having a high tear strength. The object is that the forming strand has at least one band, fiber, or braid of fibers or fibers of strong material at the heat deflection temperature of the molding strand, the strip or fiber (s) being 0 ° relative to the longitudinal axis of the core. It is achieved by forming an angle that is larger and smaller than 90 °. The reinforcing layer formed by the windings, twists, weavings, etc. has the advantageous property of being able to adapt to changes in the cross section of the forming strands caused by stretching or pulling. The cross section of the forming strand can be formed almost arbitrarily. Thus, not only is it advantageous for many applications in which shaped strands with circular or elliptical cross sections are used, but also for other uses where shaped strands with rectangular, triangular, trapezoidal cross sections are used rather than round cross sections.

As the material of the reinforcing layer, twisted strands or bands or fibers of, for example, cotton, metal, glass, ceramic, or the like are preferable. Particularly suitable are strands, fibers or strips of high temperature resistant synthetic resins such as polyesters, polyamides and the like.

In particular, it is advantageous to have the fibers or bands spirally wound on the forming strands. Such windings can be made at very high speeds. The winding may consist of multiple bands or fibers formed parallel to each other with the same twist length. Also, a plurality of fibers or strips of winding with opposite twisting directions have advantages such as knitting.

The forming strands preferably consist of crosslinked polymers. As is known, the properties returned on heating by crosslinking are improved.

Preferably a layer of thermoplastic polymer is arranged below the reinforcing layer, on which the reinforcing layer is placed. The thermoplastic layer is produced by coextrusion at the same time as the core of the crosslinkable polymer. The thermoplastic layer has the advantage that the forming strands can be connected with parts made of thermoplastic material by melt welding. Thus, for example, side by side forming strands can be processed into a single net by spot welding.

The present invention also relates to a method for producing the molded strand as described above.

In this method, a molded strand of polymer is first produced by extrusion and then crosslinked, and then heated in a continuous process to a temperature above the melting point of the polymer crystal, stretched at this temperature, cooled in a stretched state and then wound Provides kinks, weaves, etc. If the reinforcing layer adheres on the forming strands in the stretched state, smaller twist angles of the fibers are required. If the reinforcing layer is attached before stretching, a larger twist angle is needed. The twist angle should be understood as the angle between the longitudinal axis and the fiber or band. Twist lengths have been mentioned many times in cabling technology. In this case, the longitudinal axis spacing between two feedback points is dealt with. Large twist lengths correspond to small twist angles, while small twist lengths correspond to large twist angles.

In the stretching process, the cross-linked forming strands from the storage drum are guided around the first drum with at least one winding, followed by a stretching device consisting of heating and cooling sections, followed by at least one winding behind the stretching device. And the second drum is driven at a higher speed than the first drum, and the windings, twists, weaves, etc. are provided on the stretched forming strand after leaving the second drum. It has been shown to be desirable. It can be seen that the molded strand provided with the reinforcing layer can also be stretched in the manner described above. It is preferred that the diameter of the stretched forming strand is measured and compared to a predetermined value for the diameter, and as a result the drum is driven faster or more slowly, thereby controlling the second drum.

Preferably, forming strands of silane grafted polyethylene are extruded and crosslinked in the presence of water or water vapor. The cross coupling method is characterized in that it can be performed without expensive mechanical devices. In addition, crosslinking by irradiation is advantageous for very thin molded strands. Molded strands or molded strands made in accordance with the method of the present invention may be made of heat shrinkable bands according to another embodiment of the present invention, which bands may be used, for example, to cover junctions of wires or conductors. These bands consist of a number of forming strands, formed parallel to each other, impregnated in a layer of thermoplastic polymer.

The impregnation layer is preferably an extruded layer. It is of course also possible for the forming strand lying in one plane to be laminated with a band of thermoplastic polymer on both sides. The impregnated layer forms a surface adhesive layer, to which the heat recoverable forming strands are bonded. After the addition of the thermoplastic layer, the layers can be crosslinked by extrusion or laminate.

By means of the reinforcing layer of the molded strand, the strip has a sufficiently high tear strength in the shrinking direction. In order to increase the tear strength of the band in the transverse direction with respect to the shrinkage direction, so-called warp yarns may be placed around the forming strands.

Another preferred solution to this problem is to provide a fiber of material in which the forming strand has a tensile strength at shrinkage temperature in at least one of the laminated bands. The fibers extend over the entire width of the strip and are formed of a material similar to the material of the reinforcing layer.

The strip is formed according to another embodiment of the present invention, by placing a plurality of forming strands in parallel in an extruder and coating with a layer of thermoplastic polymer to form a strip having a rectangular cross section, the strip of cross-linked polymer crystals. It is produced by heating above the melting point, stretching in a heated state and cooling in a stretched state. It is of course also possible to extrusion coat the forming strands before stretching as described above, in which case the forming strands should not be heated above the shrinkage temperature. Another possibility of making the band is to make one mat from a number of molded strands and warps laid out in one plane and to coat both sides of the mat with thermoplastic polymer. In this case, the forming strand may or may not be stretched. That is, if the forming strands are not stretched, the strip is stretched after coating. Coating can be made by extrusion or laminate.

The present invention also relates to a method for producing a heat recoverable banded article of synthetic resin, in which heat recoverable fibers of crosslinked synthetic resin are impregnated between two layers of thermoplastic synthetic resin.

In this method, both sides of a plurality of single filaments laid parallel to each other in one plane are laminated with a band of thermoplastic synthetic resin in a continuous process, and between the fiber and at least one band, a layer of material that is tear resistant at heat recovery temperature. Arrange.

A single filament of high strength material may also be spirally wound around the fiber. The method described below is used when providing a helical twist of high strength material to a single stretched filament, as shown in another embodiment of the present invention. The twist prevents shrinkage and increases the tear strength of the single filament.

It is also possible, preferably, to produce a single stretched filament of intertwined fibers and to arrange heat and non-heat recoverable fibers in the strand bond. Shrinkage of a single filament reduces the twist length of the strand bond without affecting the shrinkage process. Non-thermally recoverable fibers of high failure of strand bonds significantly increase the tensile strength of a single filament.

High strength fibers should be understood as fibers having higher tensile strength than synthetic resins shrinking at shrinkage temperatures. Examples thereof include glass fibers, metal yarns, cotton yarns, polyester or polyamide fibers, and the like. Particularly preferably, a single stretched filament having a thermoplastic protective layer is used. The core of the single filament is preferably made of a crosslinked synthetic resin. Good bonding with the thermoplastic protective layer is obtained, for example, by welding to the thermoplastic laminating strips. The thermoplastic protective layer optionally prevents the single stretched filament in the core region from heating above the shrinkage temperature during the laminate process. Particularly preferably, the bands thus produced are crosslinked, for example by crosslinking by irradiation.

According to yet another embodiment, a mat or fabric is first formed of intersecting strands of a material that is non-stretchable or can only be stretched slightly, wherein the strands extending in at least one direction are spirally formed, and the mat or fabric Impregnated in this plastic material and the thus produced strip is stretched in the direction of the spirally formed strand.

An advantage of this embodiment is that the resin matrix is heat recoverable and the fabric is impregnated into the resin matrix as a reinforcing layer as in the band according to German patent publication DE-PS 15 25 815. Since the fabric has an elongation even though the material of the strand cannot be stretched by the spiral formation of the strand, the fabric impregnated with the band can be stretched to an elongation of 400% or more commonly used. During stretching, the twist length expands and the diameter of the spiral decreases. In the extreme case, the spiral is transformed into a straight strand. In the subsequent shrinkage process the strands are inserted into the resin matrix in non-uniform form.

It is particularly preferable that each of the spirally formed strands is spirally wound on one synthetic strand having any cross section. This allows a stable shape mat or a stable shape fabric to be produced, which can be pulled out of the storage coil without deformation of the nose width and supplied to the impregnation device.

According to a particularly preferred embodiment of the invention, the strip of synthetic resin material is crosslinked after the impregnation process and then heated, cooled in the stretched and stretched state in the heated state. Upon heating, the resin strands are softened, bands are wound on the strands, and then stretched together, where the strands provide the free movement space required for the helix.

Impregnation of the mat or fabric in the resin material is by extrusion or laminate. It is important at this time that the resin material penetrates into the internasal space to form a single strip-shaped body with an impregnated reinforcement layer.

The band of spiral wound synthetic resin is preferably made of thermoplastic, non-crosslinked synthetic resin. This ensures that the resin strands likewise bond well with the resin material which is in the thermoplastic non-crosslinked state.

According to a particularly preferred embodiment of the invention, the mat or fabric is extruded into silane grafted polyethylene in a continuous process, the silane grafted polyethylene is crosslinked in the presence of water or water vapor, and the crosslinked band is the melting point of the polyethylene crystal. Heated to this temperature, at least 40% stretched and cooled in the stretched state. It is obvious that other crosslinking modes are also suitable, such as, for example, peroxide crosslinking or crosslinking by irradiation. Of course, low cost cross-linking systems are particularly preferred.

Preferably, an almost infinite mat of warp and weft yarns is produced, wherein the warp yarns are straight fibers of non-stretchable material and the weft yarns are made of one or several fibers of spirally wound material. It consists of an extruded thermoplastic resin strand, the resin material is crosslinked, and the unfinished molding is separated from the strip, heated, stretched in the heated state and cooled in the stretched state. Materials for strands or fibers that cannot be stretched include fibers that can be formed into a single filament that is twisted together, such as cotton yarn, metal yarn, glass fibers.

Multiple fibers can also be wound on a synthetic strand, in which case a combination of the above materials is also possible. If silane grafted polyethylene is used as the synthetic resin matrix, a strand of polyethylene is preferred as a support for the strand of a material that cannot be stretched.

According to another preferred embodiment of the invention, the bands are crosslinked at different strengths when viewed in cross section. That is, the wall portion in contact with the object of interest has a higher crosslinking rate, for example 25-50%, and the wall portion away from the object of interest is formed, for example, with a lower crosslinking rate of 5-25%. As confirmed in the test, the tears produced by this method have a higher resistance to tearing, because the tearability increases with increasing crosslinking rate.

Preferably, the strip is produced by coextrusion of at least two layers, wherein the layers are formed of polyethylene of different strengths. By adding different crosslinkers and / or catalysts differently, a plurality of layers having different crosslinking rates are produced, and as a result, in the above method having a banded sandwich structure, polyethylene is bonded by bonding the silanes and then storing them in a damp environment. Crosslinking is particularly suitable. Due to the dynamic cooperative action of the sandwich structure, the tear strength of the band is significantly increased compared to uniform bands having the same wall thickness.

As described above, the synthetic resin layers supplied to the fabric from both sides need to be bonded to each other. In this case, if the nose width of the fabric is narrow, difficulties arise in some cases because the resin material cannot penetrate the nose due to its high viscosity. This problem is solved by one or more resin strands being woven at different intervals. For example, two or three plastic strands can be woven at relatively small intervals from one another and the next group of two or three synthetic strands can be woven at larger intervals than the preceding group. The spacing between the groups should be largely chosen so that the resinous layers are bonded to each other at this location.

1 is a view showing a molded strand according to the present invention.

2 is a view showing the molded strand in the retracted state.

3 is a schematic view showing a process for producing a molded strand.

4 to 19 show an article made from the molded strands of FIGS. 1 and 2.

Explanation of symbols for the main parts of the drawings

4,5,17,21,22,24,40: storage spool

7: stretching device

10: spinner

11,12,45,46: load

13,14,15: floor

41,42: Extruder

1 to 19, the embodiments of the present invention will be described in detail as follows.

1 shows the strand 1 of the invention in a stretched state. The forming strand 1 consists of a core 2 of thermoplastic or crosslinked synthetic resin, preferably of silane grafted polyethylene. On the core 2, a fiber or strip 3 is wound in a spiral. The fiber or strip 3 is made of a material having a higher tensile strength than the material of the core 2 at a shrinkage temperature, ie, about 130 to 150 ° C. As a material of the fiber 3, polyester, polyamide, cotton, a metal, a ceramic, glass, etc. are preferable, for example. The fibers or strips 3 are preferably formed of thin single filaments that are twisted or woven together or otherwise gathered together. The fibers or strips 3 can thus be formed of a plurality of these materials.

The core 2 may also be formed of a single filament that is twisted or woven together or otherwise combined. Thus, for example, it is also conceivable to combine a single filament of crosslinked polymer with a single filament of elastic rubber material, such as natural or artificial elastic rubber. It is also conceivable to combine a single filament of crosslinked polymer with a single non-shrinkable filament. In the above combination it is important to combine a single filament with a constant twist length that can be expanded or shrunk upon stretching or contracting of the core 2. The cross section of the core 2 or optionally the single filaments forming it may be chosen arbitrarily, for example round, oval, square, triangular or trapezoidal.

If the core 2 consists of crosslinked polyethylene, an unillustrated layer of other material, which is coextruded between the core 2 and the fiber or strip 3, preferably upon extrusion of the core 2, This can be formed. The layer should consist of uncrosslinked polyolefins, polyamides, polytetrafluoroethylenes in order for the strands 1 to have fire resistance, acid resistance and the like. Layers of uncrossed polyolefins are advantageous because different treatments offer the possibility of welding or, for example, laminating the strands with each other or with a plastic strip.

2 shows the strand in the retracted state. It can be seen that the cross section of the core 2 has increased due to the length shrinkage of the core 2. At this time, the twist of the fiber or strip 3 is reduced.

The production of the strand will be described in detail with reference to FIG. 3 as follows.

The core 2 is continuously withdrawn from the storage spool 4 and wound on the storage spool 5 after the processing to be described below. The core 2 may be formed of one or a plurality of fibers as described above. The core 2 is first guided around the drum or roller 6 with at least one winding and then into the stretching device 7, in which the core 2 is first subjected to a temperature above the microcrystalline melting point. Heated to and then cooled. In the heating zone the core 2 is stretched. An additional drum or roller 8 is used for this, around which a stretched core 2a in at least one winding is guided. The drum or roller 8 is installed to allow it to emerge from the stretching device 7 at a higher speed than when the stretched core 2a enters.

The core 2 is stretched due to the difference in entry and exit speeds. If the diameters of the drums 6 and 8 are the same, the drum 8 must be driven at a higher speed. Of course, different drum diameters are possible. The stretching ratio can be known by measuring the diameter of the core 2a stretched through the stretching device 9 and then comparing it with the diameter of the core 2 which is not stretched. The rotational speed of the drum 8 is adjusted according to the comparison result.

For example, a fiber or strip 3 having a tensile strength is provided to the core 2a stretched by the spinner 10, which is wound on the storage spool 5.

It is of course also possible for the fibers or strips 3 to be provided before stretching. In this case, the twisting length of the fiber or strip 3 changes during stretching.

4-8 show articles made with the aid of strands as shown in FIGS. 1 and 2.

4 shows a sleeve suitable for wrapping a connection of a cable or tube, for example. The sleeve has two rods 11 and 12, rounded around the connection and then pushed over the rods in a manner not shown. The rods 11 and 12 are also used as points of action of the force in the stretching process. The sleeve produced is formed in multiple layers. That is, it consists of layers 13, 14 and 15, which layers are combined into one sleeve by laminate or coextrusion. The layer 13 with rods 11 and 12 consists of a thermoplastic polymer such as polyethylene, for example. Layer 14 is formed of a mat, not shown, which consists of the individual strands of FIG. 1 or 2. The strand is formed perpendicular to the direction of the rods 11 and 12. The strands are preferably integrated into one mat by one or several fibers wound around individual strands formed transverse to the longitudinal direction of the strands.

According to another embodiment of the mat, the strands are laid in a serpentine form and coated with a layer of thermoplastic synthetic resin in the serpentine direction. Tensile strength fibers 16, extending in a serpentine direction, increase the stability and tear resistance of the sleeve. Layer 15 likewise consists of a thermoplastic polymer such as polyethylene, for example, and may have fibers with tensile strength extending parallel to rods 11 and 12 in a manner not shown.

It is also possible to produce a layer structure by coextrusion of three layers together with the laminates of layers 13, 14 and 15. In this case, it is preferable to wrap all sides of the layer with thermoplastic synthetic resin. That is, the layers 13 and 15 shown in FIG. 4 are joined in parallel to the rods 11 and 12 by edge coatings not shown. The entire edge portion near the rod is preferably crosslinked, for example by crosslinking by irradiation.

If the strands are not stretched, an unfinished sleeve made by laminate or coextrusion may be stretched.

5 to 7 show another use of the strand according to FIGS. 1 and 2.

According to FIG. 5, a number of strands as shown in FIGS. 1 and 2 are withdrawn from the storage spool 17 in parallel and flat to each other. For clarity, only one strand 1 and one storage spool 17 are shown. The strand 1 is laminated with the strips 19 and 20 withdrawn from the storage spools 21 and 22 in a pair of rollers 18. Between the strip 19 and the strand 1 a fabric 23 withdrawn from the storage spool 24 is inserted. Since the strand 1 used in the method is stretched, the laminated strip 25 is heat recoverable.

A similar method is shown in FIG. 6. A mat 26 is withdrawn from the storage spool 17, the mat consisting of an unstretched strand 1 extending in the manufacturing direction, which strand is twisted with the strand and has a tensile strength, a plurality of transversely extending strands. It is integrated into the mat 26 by the fiber of. The mat 26 is laminated with synthetic strips 19 and 20 as shown in FIG.

The strip 25 may be manufactured to an almost infinite length in a continuous process.

If the high strength fabric 23 of FIG. 5 or the fiber with the tensile strength of FIG. 6 is omitted, each method may be modified such that an unstretched strand is used and the article is stretched entirely after lamination.

A strip of length 25 is separated for the manufacture of a covering for the connection of the cable or tube (see FIG. 7). As a locking element for the covering, a C-shaped bar 34 is used which ties the ends of the strip 25 together. The end of the band 25 is wound around a flexible rod 27 and is bonded or welded to the band 25 as indicated by 28.

In the embodiment according to FIG. 8, the strand 1 of FIG. 1 is wound in the form of a spiral with a predetermined twist around the rod 27. The formation thus obtained is coated with a thermoplastic layer, for example by lamination or extrusion. In this case, since the strand 1 is wound on the rod 27 in a stretched state, the covering is completed after the resin coating. Of course, the unstretched strand 1 may be wound around the rod 27 and the formation may be coated with synthetic resin and then stretched.

In the embodiment according to FIG. 9, the stretched or unstretched strand 1 is fixed between two half halves 27a and 27b. The strand 1 is placed around the protrusion 29 and then around the corresponding protrusion 29 of the half of the rod, not shown, which extends parallel to the half of the rod 27a. The strand 1 is placed around all the projections 29, and then the bar halves 27b are fixed on the bar halves 27a by pushing, fixing, screwing or other fastening methods. The formation may also be coated with synthetic resin by extrusion or laminate before or after stretching of the strand 1. The advantage of this embodiment is that the individual windings of the strand 1 lie in one plane.

The same advantages are obtained in the embodiment of FIG. The rod 30 has an almost semicircular cross section with a shoulder 30a. There are a plurality of grooves 31 in the rod 30, which forms a block 32, around which the strands 1 are wound. In the block 32 is formed one groove 33 extending in the longitudinal direction, in which the edge of the C-shaped bar 34 lies (see FIG. 11).

12 shows a band 25 produced by the method of the present invention. A number of pre-stretched single filaments 1 are laid on or impregnated in the strip 20 on the synthetic strip 20. The plane of the single filament 1 is covered by the fabric 23, on which a strip 19 is laid.

Figure 13 shows another embodiment of a strip 25 made in accordance with the method of the present invention, where the fabric 23 (see Figure 12) has a tensile strength of cotton, metal, glass or high strength synthetic resin instead. The fibers 35 are spirally wound around a single filament 1 lying in one plane.

The strip 25 produced by the method according to the invention is particularly suitable for covering articles with different diameters. Preferred applications are moisture resistant coverings of cable or pipe connections. A strip is drawn from the coil and placed around the connection and mechanically joined at its ends to produce the covering. Then, for example, with a weak flame, the band 25 is heated until it starts to contract. Due to the laminate structure, the outer covering of the strips from the strips 20 and 19 participates in the shrinkage generated by the single filament 1. In other words, the strip 25 lies smoothly on the connection. An adhesive or sealant layer formed on the surface facing the junction of the strip 25 is provided for good packing. If the twisted portion of the single filament 1 is formed of metal or there is a strand of metal in the twisted joint in the case of the twisted joint, the heating for shrinkage can be made simply by current heating.

14 shows a mat or fabric 36 formed of crossed fibers 37 and 38. The fiber 38 is formed of a polyethylene strand 38a, on which the fiber 38b of another metal is wound in a spiral form. Fibers 37 and 38b are made of a non-stretchable material such as, for example, glass, cotton, metal, and the like. Particularly preferably, the fibers 37 and 38b consist of a plurality of flattened glass fibers. The fiber 38 can be stretched because the excess length or ductility is obtained by the spiral wound.

In the stretching process, the diameter of the synthetic resin fibers 38a and the narrow width of the spirally wound fibers 38b are reduced. In the extreme case, the fiber 38b extends straight in parallel after the stretching process. The spacing of the fibers 37 is increased by the stretching factor during stretching. The fabric 36 can be made long on standard looms.

The fabric 36 shown in FIG. 14 may be impregnated into a resin matrix in a continuous process. Such bands are shown in FIG. 15, in which a synthetic resin matrix 39 is indicated.

Synthetic resin fibers 38 are first produced by extrusion for the production of the strips, which are wound by twisted glass fibers 38b having a relatively short twist length after cooling.

Example

Polyethylene Fiber Diameter: 1mm

Fiberglass Diameter: 0.05mm

Twist Length Diameter of Glass Fiber: 1mm

The fiber 38 may be stretched by up to about four coefficients. The fibers 38 are woven into a fabric with 0.05 mm diameter glass fibers, inserted into the warp yarns, in a loom not shown as wefts.

As shown in FIG. 16, the fabric 36 is continuously withdrawn from the spool 40 into the head 41 of the extruder 42, where it is impregnated in the resin matrix 39. The strip 43 thus produced is cut into portions 44, which portions can be stretched transverse to the extrusion direction as indicated by the arrows.

As a material for the resin matrix

50 parts polyethylene

40 parts ethylene-vinylacetate copolymer

And 10 parts carbon black

The mixture is prepared and granulated. The granules are placed into the funnel of the extruder 42 together with about 1% by weight vinylmethoxysilane and formed into a strip with a wall thickness of about 4 mm around the fabric 36.

If the band has a multi-layer structure, it can be produced, for example, by coextrusion of two layers, in which case the fabric 36 is arranged between these layers. In order for the layers to have different crosslinking rates, the amount of vinylmethoxysilane must be reduced to, for example, 0.2 to 0.5% by weight.

The separated portion 44 is crosslinked at about 95 ° C. in the presence of water vapor. It is apparent that the portion 44 can be separated from the strip 43 after crosslinking.

The crosslinked portion 44, which is marked as incomplete, is stretched about four times in length in an unillustrated stretch. The stretching process is performed at about 120-150 ° C., wherein the synthetic strand 38a is softened, and its cross section is reduced by the stretching process, so that the shape change of the spirally wound fiber 38b is inevitable.

The stretched strip then has a wall thickness of about 1 mm. In the stretched state, the strip is cooled to room temperature and ready for use. In other words, upon reheating, the strip attempts to shrink back to the shape made during extrusion.

17-19 show various embodiments of a wound bushing or sleeve reinforced with fabric.

According to FIG. 17, the winding bushing has the same form as that used for covering the cable connection. The strip 43 has two rods 45 and 46 at its longitudinal edge and a bracket 47 extending over the region of the rod 45. Placing a strip around the connection places the bracket 47 under the region of the rod 46. As is known from German patent DE-PS 15 25 815, the tubular shape of the strip 43 is maintained by pushing up a bar, not shown. For sealing of the bushing, the strip 43 has a known adhesive layer not shown in detail on its surface facing the connection. In the wound bushing shown in FIG. 17, the fabric 36 is arranged inside the wall of the strip 43, which extends to the regions of the rods 45 and 46. German patent DE-PS 15 25 815 It is different from the bushings known in the call. The fabric 36 increases the tear strength and compressive strength of the strip 43 at shrinkage temperature.

18 shows another embodiment of the winding bushing. The longitudinal edges of the strips 43 are rounded in a loop, and within the loops are arranged flexible bars 48 and 49, for example, of mutually twisted glass fibers. The rods 48 and 49 are wrapped by the bars described above after forming a strip 43 around the cable connection. The loop is formed by adhering and / or sewing or securing the overlapped portions. Winding the edges of the strip around the bars 48 and 49 takes place immediately after the extrusion process, since it is then possible to weld the overlapping parts which are not crosslinked to each other. Also here the fabric 36 extends to the longitudinal edge of the strip 43. That is, the edges of the fabric wind the rods 48 and 49.

19, another preferred embodiment is shown. Rods 48 and 49 are wound with fabric 36. This embodiment particularly preferably places the longitudinal edges of the fabric 36 around the rods 48 and 49 while forming each loop and secures the formations by stitching the overlapping portions, then stitching the formations together. It is prepared by extrusion coating in an extruder together with a resin matrix. The convex portions formed by the rods 48 and 49 are used here as a means of being enclosed by the locking bar.

An advantage of the present invention is that a single filament can be laminated without inter weave immediately after stretching. The tear strength of the band is increased by the layer of tear resistant fibers.

When the tear resistant layer is a coarse fabric, the tear strength of the band is increased in the vertical direction as well as in the shrinking direction. Coarse fabrics are advantageous because the plastics that are fired upon lamination can penetrate through the rough nose and be welded with a single filament or with a second plastic that is in the fired state.

The tear strength of the band perpendicular to the shrinkage direction can be increased by placing a single filament of high strength material in a serpentine shape on the fiber prior to the laminate.

Claims (7)

A plurality of single filaments extending parallel to each other in one plane are laminated with a band of thermoplastic resin on both sides in a continuous process, and a layer of material with tensile strength at heat recovery temperature is arranged between the single filament and at least one band. A method of producing a heat recoverable strip article made of synthetic resin, wherein the heat recoverable fiber of synthetic resin crosslinked is impregnated between two layers of thermoplastic synthetic resin. 2. The method of claim 1, wherein a coarse fabric, knitted fabric, or the like, of fibers having tensile strength prior to lamination, is inserted between the fibers and the strip. 3. A method according to claim 2, wherein a single filament of high strength material is laid on the single filament before the laminate. 3. A method according to claim 2, wherein a single filament of high strength material is spirally wound around the fiber. The method of claim 1, wherein the stretched single filament is provided with a spiral twist of high strength material. The method according to any one of claims 1 to 4, characterized in that the stretched single filaments are made of fibers twisted together, and in the strand bond are arranged fibers of heat recoverable synthetic resin and fibers of high strength material. How to. 5. The method of claim 1, wherein the thermoplastic layer is provided in a single twisted filament or strand combination. 6.