JPH01301228A - Method of molding tubular body - Google Patents

Abstract

PURPOSE:To stably mold the innermost tubular body equipped with a waterproof layer, by heating a hot melt adhesive after the innermost tubular body is formed to bring the same to a perfectly molten staste and fonding an opposed strip like body in this state. CONSTITUTION:A mandrel is provided to an inner surface layer molding apparatus G so as to extend to a heat-molding apparatus H and opposed to the non- stretched polypropylene film (CPP) 5 having heat weldability and water resistance formed to the upper surface of a strip like body X. The strip like body X is molded into a tubular shape along the mandrel in the inner surface layer molding apparatus G and, subsequently, a hot melt adhesive is heated in the heat-molding apparatus H to be brought to a perfect molten state and strip like bodies Y, Z are molded into a tubular shape along the strip like body X molded into a tubular shape to form a tubular body 1. The strip like bodies X, Y, Z form the inner layer 2, intermediate layer 3 and outer surface layer 4 of the tubular body 1 respectively. Thereafter, the tubular body is drawn out by a draw-out apparatus to be cut into a proper length by a cutter J.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is a method for continuously forming a tubular body with a multilayer structure, the innermost surface of which is a heat-weldable waterproof layer, by polymerizing and bonding a plurality of flexible strips. Regarding how to.

(Prior Art) In the method previously proposed as the above method, a plurality of flexible strips facing each other with an interval above and below are continuously supplied under tension in the longitudinal direction. . Among the plurality of strips, the uppermost strip has a heat-weldable waterproof layer on its upper surface. As the waterproof layer, for example, an unstretched polypropylene film (referred to as CPP) having heat-weldability and water resistance is used. A hot melt adhesive in a molten state is applied to the upper surface of the other strip. On the side where these strips are fed, a mandrel is provided in the feeding direction, and the mandrel faces the waterproof layer at a position midway between both edges of the uppermost strip. The uppermost strip facing the mandrel is gradually bent along the mandrel while moving in the supply direction to form a tubular shape, and its both side edges are joined by heat welding to form the innermost tubular body around the mandrel. is formed. Next, another strip is bent along the innermost tubular body while moving in the supply direction to be formed into a tubular shape, and is also polymerized and bonded to form a multilayered tubular body.

A tubular body formed by such a method is easy to manufacture, has excellent pressure resistance, and has good sealing properties of the innermost tubular body.

In the above method, it is necessary to keep the hot-melt adhesive in a sufficiently molten state when each strip is polymerized so as to prevent problems such as wrinkles and non-bonding during formation of the tubular body. Therefore, in the process of feeding each strip toward the mandrel, the adhesive is heated. However, due to the heating, the heat-weldable waterproof layer of the uppermost strip is also heated. For example, when CPP is used as the waterproof layer, the CPP is heated as the temperature of the solvent contained in the CPP increases.
The sliding resistance of the waterproof layer increases, the sliding of the CPP surface worsens, and when the innermost tubular body is formed, the sliding resistance increases at the contact area between the waterproof layer and the mandrel.

For this reason, the tension applied to the strip having the waterproof layer becomes uneven between the contact portion and other portions, and distortion occurs in the strip. As a result, the innermost tubular body is formed with the band-shaped body being distorted, resulting in a problem that stable molding cannot be performed.

(Problems to be Solved) The present invention eliminates such inconveniences in molding a tubular body having a multilayer structure whose innermost surface is a heat-weldable waterproof layer, and enables stable molding of the tubular body. In particular, it is an object of the present invention to provide a method capable of stably molding an innermost tubular body provided with the waterproof layer.

(Means for Solving the Problems) The method for forming a tubular body of the present invention is characterized in that a plurality of elongated strips made of a flexible material facing each other with a gap are formed in a small number (at least one side of the tubular body is made of molten real-melt adhesive). The innermost strip of the plurality of elongated strips, the inner surface of which is made of a heat-fusible layer, is coated with an agent and continuously supplied under tension in the longitudinal direction, and the innermost strip of the plurality of elongated strips is coated with a heat-fusible layer, and the innermost strip of the plurality of elongated strips is coated with a heat-fusible layer. It is gradually bent along a mandrel provided in the longitudinal direction facing the heat-fusible layer to form a tubular shape, and the both side edges are joined by heat welding to form an innermost tubular body, and the other elongated A method in which the strip is gradually bent along the innermost tubular body to form a tubular shape, and the opposing strips are polymerized and bonded together with the hot melt adhesive to form a complete tubular body. After the inner tubular body is formed, the adhesive is heated to a completely melted state, and the facing strips are bonded in this state.

(Function) By adopting the method described above, the hot melt adhesive is heated after the innermost tubular body is formed, and the temperature increase in the heat-fusible layer is prevented during the formation of the innermost tubular body. Prevented.

When the strips are bonded to each other, the hot melt I/adhesive is in a completely molten state due to the heating.

The flexible strip used in the present invention can be paper, plastic,
Made of materials such as metal foil. Moreover, you may use these materials in combination. The belt-shaped body is made of a continuous long sheet material, and the formed tubular body is appropriately cut into predetermined dimensions for use.

A belt-like body having a heat-fusible layer is constructed by laminating a synthetic resin film such as an unstretched polypropylene film (CPP) on the above-mentioned belt-like body.

The hot melt adhesive used in the present invention may be a known and commonly used adhesive (polyethylene alone, ethylene and ethylene copolymer, ethylene vinyl acetate copolymer, ethylene methyl methacrylate copolymer, ethylene ethyl acrylate copolymer, etc.). Polymer, ethylene methyl acrylate copolymer, ethylene ethyl acrylate maleic anhydride copolymer, ethylene acrylic acid copolymer, ethylene methacrylic acid copolymer, ionomer resin, polyamide resin,
Polyester resins, nylon resins, polypropylene resins, vinyl acetate copolymer resins, polymethyl methacrylate resins, and the like may be used alone or in combination.

A hot melt adhesive is applied and formed on at least one side of the strip. A hot melt adhesive may be applied to both surfaces of the strip forming the intermediate layer.

(Example) FIG. 1 shows a cross-sectional view of a tubular body 1 formed in this example. In this embodiment, a tubular body 1 is formed which includes an inner layer 2, an intermediate layer 3, and an outer layer 4. Each layer 2, 3.4 is made of paper material, and the inner surface of the inner layer 2 is a non-stretched polypropylene film (referred to as CPP) 5 that has heat-weldability and water resistance.
is laminated.

An example of a method for forming this tubular body 1 will be outlined with reference to FIGS. 2 and 3. Figures 2 and 3 are
1 is a schematic diagram of an example of a device implementing the invention; FIG.

In this method, first, a strip X having the CPP5 laminated on its upper surface and a paper strip Y are fed into a feeding device.
The Zs face each other with an interval above and below and are continuously fed out. The vertical relationship among the strips X, Y, and Z is such that strip X is at the top and strip Z is at the bottom. The rolled-out strip x,
y and z are heated and uniformly dried by the strip preheating device B, and then both side edges of each strip X, Y, and Z are accurately positioned by the first positioning device C.

Hot-melt adhesive is applied in a molten state by an adhesive applicator to one side of each of the strips x, y, and z facing each other, whose side edges are positioned, and is heated by an adhesive preheating device E to apply the adhesive. This prevents the adhesive from solidifying. Next, each strip X, Y, Z is moved by the second positioning device F.
The both side edges of are again accurately positioned, and each strip X is fed to the inner layer forming apparatus G where the inner layer 2 of the tubular body 1 is formed. The inner layer forming device G includes a heating forming device H, which will be described later.
A mandrel (not shown) is provided across the strip, and the mandrel faces the CPP 5 on the top surface of the strip X.

In the inner layer forming device G, the strip X is molded into a tubular shape along a mandrel, and then in the thermoforming device H, the hot melt adhesive is heated to a completely melted state, and the strips Y and Z are The tubular body 1 shown in the first figure is formed by being shaped into a tubular shape along the tubular strip X. Each of the strips X, Y, and Z includes an inner layer 2, an intermediate layer 3, and an inner layer 2 of the tubular body 1, respectively. An outer layer 4 is formed. ``Thereafter, the tubular body 1 is pulled out by a drawing device I, and cut into an appropriate length by a cutting device J. Each strip X, Y.

Z is given tension in its longitudinal direction by the drawing device I during the above-mentioned forming process.

FIGS. 4 and 5 show how the strips X, Y, and Z are fed from the adhesive applicator to the inner layer forming device G. Fig. 4 is a plan view, and Fig. 5 is a plan view of Fig. 4.
FIG.

In FIGS. 4 and 5, the strip X advances toward the mandrel 6 on the horizontal line of the lower surface of the mandrel 6, and is gradually bent along the mandrel 6 from near the end of the mandrel 6 in the inner layer forming device G. and formed into a tubular shape. Although not shown, side edges of the tubular strip X are joined by heat welding and folded back to form the inner surface layer 2 as shown in the first diagram. On the other hand, the strips Y and Z are coated with true melt adhesive on their upper surfaces by a coating nozzle 7 in an adhesive coating device, and are gradually bent as they enter the mandrel 6 at an appropriate angle.
In the thermoforming device H, the lower surface of the mandrel 6 is pressed against the lower part of the mandrel 6 by the first forming roller 8 and not bonded to each other, so that the lower surface thereof is formed into a tubular shape. At this time, the band-shaped body X has already been formed into a tubular shape. Furthermore, the adhesive preheating device E is heated internally to prevent the adhesive from solidifying when the strips Y and Z coated with hot melt adhesive advance toward the mandrel 6. ing. The heating temperature at this time is set to such a level that the hot melt adhesive does not solidify.

FIG. 6 shows how after the strip X is formed into a tubular shape, the strips Y and Z are formed into a tubular shape in a thermoforming device H.

After the strip X is formed into a tubular shape by the inner layer forming device G, the hot melt adhesive is heated by the thermoforming device H and the strips Y and Z are shaped into tubular shapes. The forming is performed by gradually pressing the strips Y and Z against the mandrel 6 by several forming rollers (not shown) provided around the mandrel 6 in the longitudinal direction, similar to the first forming roller 8. It will be done. Band Y
.

Z is pressed against the mandrel 6 and at the same time each strip x
, y, z are glued, but at this time, each strip x, y,
In order to prevent harmful effects such as wrinkles and non-adhesion of Z, the true melt adhesive must be in a completely molten state. In this embodiment, immediately before the strips Y and Z are pressed against the mandrel 6 and bonded, the forming heaters 9 to
14, heated air is blown onto the hot melt adhesive to completely melt the adhesive. The state of heating by each forming heater 9 to 14 is shown in the seventh column.
Shown in Figures (a) to (e). The heated portion is then pressed against the mandrel 6 and bonded as shown in FIG. The heating temperature by the forming heaters 9 to 14 is set depending on the type of hot melt adhesive used and the line speed, etc., but this temperature is set as above in order to completely melt the hot melt adhesive in a short time. The temperature is set relatively high compared to the heating by the adhesive preheating device E.

As mentioned above, the heating at a relatively high temperature by the forming heaters 9 to 14 is performed after the band-shaped body X is formed into a tubular shape, and when the band-shaped body X is formed into a tubular shape,
temperature does not rise relatively. Therefore, CP of band X
The slip resistance of P5 is small, and the C of mandrel 6 and strip X
The slip resistance at the contact portion with PP5 is relatively small, and the strip X is smoothly formed into a tubular shape. This will be more effective if the mandrel 6 is cooled. In addition, by heating the forming heaters 9 to 14 at a relatively high temperature, the hot melt adhesive is completely melted, and even when the strips Y and Z are formed into tubular shapes, there are no wrinkles or unbonded parts. No harm will occur.

In this example, the tubular body 1 having a three-layer structure was molded, but it is also possible to mold a tubular body consisting of even more layers.

(Effects of the Invention) As is clear from the above description, in the tubular body forming method of the present invention, the hot melt adhesive is heated after the innermost tubular body is formed. 2. When the innermost tubular body is formed, the temperature of the heat-fusible layer is prevented from rising, and an increase in slip resistance can be prevented at the contact area between the mandrel and the heat-fusible layer, and the innermost tubular body can be stably molded.

Furthermore, by bringing the hot melt adhesive into a completely molten state, it is possible to stably mold a multilayered tubular body by preventing problems such as wrinkles and non-bonding.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the tubular body, and FIGS. 2 and 3 are
4 and 5 are explanatory views for explaining how the inner surface layer of the tubular body shown in FIG. 1 is formed; 5 is a plan view, FIG. 5 is an end view taken along the line V-V in FIG. 4, and FIG. FIG. 7 is an explanatory diagram for explaining how the hot melt adhesive is heated. l...Tubular body 2...Innermost tubular body, 5...
・Thermofusible layer 6...Mandrel, x, y, z・
...band body FIG. 7(b) Φ FIG, 7(e)

Claims (1)

[Claims] 1. Continuously feeding a plurality of long strips made of flexible material facing each other at intervals, coated with molten hot melt adhesive on at least one side, and tensioned in the longitudinal direction. and the innermost strip among the plurality of strips, the inner surface of which is made of a heat-fusible layer, is disposed along a mandrel longitudinally provided facing the heat-fusible layer at an intermediate position between both edges thereof. It is gradually bent and formed into a tubular shape, and the both side edges are joined by heat welding to form an innermost tubular body,
In the method, the other strips are gradually bent along the innermost tubular body to form a tubular shape, and the opposing strips are polymerized and bonded by the hot melt adhesive to form a complete tubular body. A method for forming a tubular body, characterized in that after the innermost tubular body is formed, the hot-melt adhesive is heated to a completely melted state, and in this state, the facing band-shaped bodies are bonded.