JPS6359374B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing a heat-shrinkable tube from a flat base tape made of a thermoplastic resin or a rubber composition, and a flat adhesive tape such as a hot-melt adhesive. This invention relates to a method for manufacturing heat-shrinkable tubes that has excellent adhesion properties and that enables the continuous production of heat-shrinkable tubes whose shrinkage rate, thickness, length, etc. can be freely selected depending on the purpose of use. . Conventionally, this type of heat-shrinkable tube was manufactured by pressing a raw material tube extruded from an annular die of an extruder into the tube at a temperature above the softening point and below the melting point. This method is used to expand the diameter and solidify by cooling, or to manufacture thick-walled heat-shrinkable tubes. After heating the raw material tube above the heat distortion temperature and sealing one end of the cylindrical product, gas or liquid Generally, a method has been adopted in which the material is press-fitted into the tube, expanded until it comes into close contact with the inner wall of the sizing pipe, and then cooled and solidified. However, since all of the above methods are molded using an annular die, the diameter and wall thickness of the resulting heat-shrinkable tube are naturally limited to the shape of the die, and from this, the desired heat shrinkage rate, diameter, wall thickness, etc. Since dies must be prepared each time according to the type of product to be manufactured, this not only increases the manufacturing cost of the product but also complicates the manufacturing process, especially in the latter method, since continuous molding cannot be performed. Manufacturing has become extremely complex,
Furthermore, the uses of the resulting product are limited, and furthermore, pinholes that occur during molding impair waterproof and anticorrosive effects. The present invention was invented in view of the above, and
The purpose of the present invention is to provide a method for manufacturing a heat-shrinkable tube that allows continuous molding of heat-shrinkable tubes whose shrinkage rate, thickness, length, etc. can be freely selected according to the purpose of use, and which also Previously, a method was adopted in which the tube was manufactured using a cylindrical raw material tube discharged from an annular die, but in the present invention, the flat adhesive tape and base material tape discharged from a flat die are attached to a rotating shaft. It is an object of the present invention to provide a method for manufacturing a heat-shrinkable tube by joining or weight joining the above-mentioned tapes, which are supplied to a body and wound back and forth. Embodiments of the present invention shown in the drawings will be described below, and its features will be explained in detail. FIG. 2' is a die for forming a flat adhesive tape B such as a hot melt adhesive, which is wound around the circumferential surface of the rotating shaft body 1 to form an inner tube A made of an adhesive layer. A die is shown for molding a flat base tape D made of thermoplastic resin or rubber composition, which is wound around the circumferential surface of the rotating shaft body 1 to mold the outer tube C. The rotating shaft 1 shown here consists of a set of multiple rolls 1a, each of which is arranged in parallel along one virtual circumference so as to maintain a constant distance between adjacent rolls. One end of each is rotatably supported by a base plate 3 and the other end is rotatably supported by a bearing plate 4 provided opposite to the base plate 3, and the entire combination substantially constitutes one rotating shaft body 1. It's like this. Further, in this embodiment, each of the rolls 1a is made into a hollow body, and the shaft 5 at one end thereof is also made into a hollow shaft to communicate with each other, and a water supply pipe 6 for cooling water is connected to each end of this shaft 5, and each roll 1a is made into a hollow body. The other end of 1a and the central shaft 7 are connected with a pipe material (not shown) to communicate the inside, thereby supplying cooling water, which is force-fed through the water pipe 6, to each roll 1a to cool it. The cooling water sent therewith is collected in the hollow part of the central shaft 7 through the pipe material and drained from the end of the central shaft 7, so that the rotary shaft body 1 can be cooled internally. Further, each roll 1a rotates a bearing plate 4 in one direction by a required angle with respect to the substrate 3, and one end of each roll 1a that is supported on the substrate 3 is supported on the bearing plate 4, and the bearing plate 4 on the other end is By shifting the
That is, by twisting and tilting each roll 1a about the center line of the rotating shaft 1, the tape B wound on the rotating shaft 1 is wound spirally. A sprocket (not shown) is provided at the shaft end of each roll 1a on the substrate 3 side, and a chain (not shown) connected thereto rotates each roll 1a in the same direction at a constant speed. Substantially the circumferential surface of the rotating shaft body 1 is configured to rotate. A flat adhesive tape B made of a hot-melt adhesive or the like discharged from the die 2 of an extruder is supplied to the rotating shaft body 1 constructed in this manner along the circumferential surface of the rotary shaft body 1 in a spiral direction. Next, the adhesive tape B was continuously wound, and at the same time, the leading edge side of the adhesive tape B that was wound later was joined to the trailing edge side of the adhesive tape B that was wound earlier. By pressing the parts together with a pressure roll 11, an inner tube A made of an adhesive layer is continuously formed on the circumferential surface of the rotary shaft body 1. Next, the flat base tape D made of thermoplastic resin, rubber composition, etc. discharged from the die 2' of the extruder is once sheeted and then stretched.
It is supplied onto the circumferential surface of the inner tube A along the spiral direction. That is, this flat base material tape D is discharged from the die 2' of the extruder and is formed by the sheeting roll 8 while being wound onto the inner tube A on the rotating shaft 1, and then stretched. After being maintained at a required temperature, the tape is stretched 2 to 8 times in the machine direction depending on the speed ratio between the rolls of the stretching rolls 9, thereby forming the base tape D. The reason why the stretching ratio of the base tape D is set to 2 to 8 times is that if the stretching ratio is less than 2 times, a heat-shrinkable tube having the desired shrinkage ratio cannot be obtained, whereas if it is more than 8 times, However, it is difficult to stretch and has poor formability. Next, the base tape D is heated to the optimum temperature for fusion using a preheating roll 10 or the like, and is supplied onto the inner tube A wound around the circumferential surface of the rotating shaft body 1 while being taken off.
At the same time as being continuously wound, the front edge side of the base tape D to be wound later is overlapped with at least the upper surface of the rear edge side of the base tape D that was wound earlier, and this overlapping part is pressed. By press-bonding with rolls 11' to form the outer tube C, a tube body having an adhesive layer on the inner circumferential surface is continuously formed on the circumferential surface of the rotating shaft body 1, and is taken off while being cooled. . As for the molecular orientation of the base tape D, as shown in FIG. 2, instead of the above-mentioned stretching process, it may be carried out by applying a predetermined draft rate and drawing it down. In this case, while being discharged from the die 2' and wound onto the inner tube A on the rotating shaft 1, the
% draft rate and oriented in the longitudinal direction. The reason why the draft rate is set to 200 to 1000% is that if it is less than 200%, a heat shrinkable tube with the desired shrinkage rate cannot be obtained.
If it is 1000% or more, use base tape D when drafting.
Poor moldability, such as cutting. The present invention has been described above with reference to embodiments, but as is clear from the above, the present invention applies a flat adhesive tape such as a heat-meltable hot-melt adhesive discharged from a die of an extruder onto a rotating shaft. The adhesive tape is supplied along the helical direction and wound continuously, and at the same time the front edge side of the adhesive tape that is wound later is joined to the trailing edge side of the adhesive tape that is wound first. An inner tube made of an adhesive layer is continuously molded on the circumferential surface of the rotating shaft by pressing it with a pressure roll, and the thermoplastic resin or rubber composition that is heated and melted is discharged from the die of another extruder. A flat base tape for objects, etc. is drawn down at a predetermined draft rate, or once sheeted, it is stretched at a predetermined magnification in the flow direction depending on the speed ratio between the rolls, and then the rotating shaft is first drawn. At the same time, the adhesive tape is supplied onto the adhesive tape wound above and continuously wound. At the same time, the leading edge side of the base tape to be wound later is applied to at least the upper surface of the trailing edge side of the previously wound base tape. By overlapping and pressing the overlapping parts with a pressure roll to form an outer tube, a tube body having an adhesive layer on the inner circumferential surface on the circumferential surface of the rotating shaft body can be continuously molded. Since heat-shrinkable tubes are manufactured, the thickness and length of the tube can be freely selected depending on the purpose of use.Therefore, the length of the tube is not limited as in the past, and can be adjusted according to the diameter and wall thickness. There is no need to select a die, and the shrinkage rate is selected depending on the stretching ratio or draft rate applied to the flat tape, which greatly improves moldability, eliminating the problems of limited use and high cost of conventional products. Furthermore, since the adhesive layer is layered on the inner peripheral surface of the tube, it not only improves the bonding with the covering but also closes the pinholes caused by molding. Waterproofing and anticorrosion effects can also be improved. The present invention will be described below with reference to Examples, but the present invention is not necessarily limited to these Examples. Example 1 A flat adhesive tape such as hot-melt adhesive that can be heated and melted is discharged from an extruder die having a diameter of 45 mm in width and 0.6 mm in thickness, and is supplied onto a rotating shaft along a spiral direction. At the same time as the adhesive tape is wound continuously, the leading edge side of the adhesive tape wound later is joined to the trailing edge side of the adhesive tape wound earlier, and the joined part is crimped with a pressure roll. By doing so, an inner tube made of an adhesive layer is continuously formed on the circumferential surface of the rotating shaft, and a sheeted flat tube is extruded from an extruder die with a diameter of 120 mm and a thickness of 1.15 mm. A polyvinyl chloride base tape is stretched 2.0 to 6.0 times with a stretching roll at a temperature of 110°C, and then supplied along the spiral direction onto the above adhesive tape wound on a rotating shaft, and continuously wound. At the same time, the front edge side of the tape wound from behind is overlapped with at least the upper surface of the trailing edge side of the previously wound tape, and this overlapping part is cooled while being pressed with a pressure roll,
A heat-shrinkable tube having an adhesive layer on the inner peripheral surface as shown in Table 1 was obtained.

[Table] Example 2 A flat adhesive tape such as hot-melt adhesive that can be heated and melted is discharged from an extruder die having a diameter of 45 mm in width and 0.6 mm in thickness, and is placed on a rotating shaft along a spiral direction. At the same time, the front edge side of the adhesive tape that is wound later is joined to the trailing edge side of the adhesive tape that was wound earlier, and the joined part is pressed into a roll. The temperature of the resin discharged from the die of the extruder, which has a diameter of 64 mm and a thickness of 1.15 mm, is continuously molded on the circumferential surface of the rotating shaft by crimping the inner tube with an adhesive layer. A polyvinyl chloride base tape at 160°C is oriented while applying a draft rate of 182 to 1094%, and the obtained base tape is spirally wound onto the above adhesive tape wound on a rotating shaft. At the same time, the front edge side of the tape to be wound from behind is overlapped with at least the upper surface of the trailing edge side of the previously wound tape, and this overlapping part is pressed with a pressure roll. cool,
A heat-shrinkable tube having an adhesive layer on the inner peripheral surface as shown in Table 2 was obtained.

【table】

[Table] The tape was cut and measurement was not possible.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIGS. 1 and 2 are explanatory perspective views showing the tape supply state, and FIGS. 3 and 4 show the manufactured shrink tube along the axial direction. FIG.

Claims (1)

[Scope of Claims] 1. When a flat adhesive tape such as a hot-melt adhesive that can be heated and melted is discharged from a die of an extruder and is supplied along a spiral direction onto a rotating shaft body and continuously wound. At the same time, the front edge side of the adhesive tape wound later is joined to the rear edge side of the adhesive tape wound earlier, and the joined part is crimped with a pressure roll, so that the peripheral surface of the rotating shaft body is bonded. An inner tube consisting of an adhesive layer is continuously molded on top, and a flat base tape made of heat-meltable thermoplastic resin or rubber composition discharged from the die of another extruder is applied at a predetermined draft rate. The adhesive tape is then drawn down or once sheeted and then stretched at a predetermined magnification in the flow direction depending on the speed ratio between the rolls, and then continuously supplied onto the adhesive tape previously wound on the rotating shaft. At the same time, the leading edge side of the base tape to be wound later is overlapped with at least the upper surface of the trailing edge side of the base tape previously wound, and this overlapping part is pressed with a pressure roll. 1. A method of manufacturing a heat-shrinkable tube, comprising the steps of: forming an outer tube, and then continuously molding a tube having an adhesive layer on its inner circumferential surface on the circumferential surface of a rotating shaft body. 2. The method for manufacturing a heat-shrinkable tube according to claim 1, wherein the base tape has a draft ratio of 200 to 1000%. 3. The method for manufacturing a heat-shrinkable tube according to claim 1, wherein the stretching ratio of the base tape is 2 to 8 times.