JPH0655434B2 - Method for forming tubular perforated film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a cylindrical hole in which a hole is formed in a cylindrical film on the way from being extruded from a mold into a cylindrical shape to reaching a nip roll. The present invention relates to a method for forming an opening film.

(Prior Art) Generally, there is an inflation method as a method for forming a tubular film.

This inflation method, by blowing a certain amount of air into the hollow portion of the molten tube extruded in a cylindrical shape from the mold and inflating to a predetermined diameter, the cylindrical film,
With the two guide plates in contact with the outer surface side, the nip rolls are gradually flattened in the axial direction and wound up by both nip rolls, and the rolled up flat tubular film is continuously wound up by a winder. It is the one.

(Problems to be solved by the invention) However, when it is necessary to open a hole in the tubular film in the middle of the process from being extruded in a tubular shape from the mold to reaching the nip roll, air is not allowed in the hollow portion of the tubular film. Therefore, there is a problem that the inflation molding using the enclosed air pressure and the wrinkle extension at the time of winding with the enclosed air pressure and the guide plate cannot be performed, and thus the conventional inflation method cannot be used at all.

(Means for Solving Problems) The present invention has been made to solve the above problems, and an object thereof is to allow inflation molding even with a tubular perforated film. In addition, the present invention provides a method for forming a tubular perforated film that can be continuously wound in a wrinkle-free state. A method of forming a tubular perforated film in which holes are opened in the tubular film on the way from the opening to the nip roll, in which the tubular film extruded from the mold is blown with air inside. , A small-diameter tubular film having a predetermined diameter by being in contact with the inner surface of the tubular film and having a large number of drawing guide members formed so that the diameter gradually increases from the lower side to the upper side. After gradually enlarging, the method was adopted in which a wrinkle-stretching guide member, which is also in contact with the inner surface side of the tubular film, pushes the nip roll flat in the axial direction.

(Operation) In the method for forming a tubular perforated film of the present invention, the tubular film extruded from the mold is expanded to a predetermined diameter by the stretching guide member in contact with the inner surface of the tubular film. As a result, inflation molding of a tubular perforated film becomes possible.

Further, in the present invention, since it is formed while blowing air into the inside of the tubular perforated film, it is possible to increase the cooling rate of the resin and improve the productivity,
Further, since the contact resistance with the stretching guide member can be reduced by the air, it is possible to prevent the tubular perforated film from being damaged.

Further, as described above, the tubular film expanded to a predetermined diameter is pushed flat toward the axial direction of the nip roll by the wrinkle-stretching guide member that is in contact with the inner surface of the tubular film. You will be able to wind it continuously.

(Example) Hereinafter, the Example of this invention is described in detail based on drawing. In this embodiment, the case where a foaming agent is used as a means for making a hole in the tubular film is taken as an example.

First, the configuration of the molding apparatus used in the examples of the present invention will be described.

As shown in FIGS. 1 to 3, the molding apparatus A of this embodiment has a point that the resin melted from the mold 1 is extruded into a tubular shape, and the flat tubular film F2 wound by the nip roll 4 is wound. Is substantially the same as the conventional inflation molding apparatus in that it is continuously wound around the winder 6 via the guide roller 5, but the drawing guide member 2 is provided between the mold 1 and the nip roll 4. And a guide member 3 for wrinkle straightening, which is different from the conventional device.

That is, the stretching guide member 2 is an inflation member for forcibly enlarging the small-diameter tubular film extruded from the mold to a predetermined diameter. In this embodiment, the stretching guide member 2 is hung at the center of the mold 1. A large number of disc-shaped guide members 21 are attached to the outer circumference of the provided air pipe 20, and the diameter of each disc-shaped guide member 20 gradually increases as it goes upward.

Therefore, a small-diameter tubular film F1 extruded from the mold 1
Is gradually expanded to a predetermined diameter by a large number of disc-shaped guide members 21 in contact with the inner surface side thereof, and is stretched by the forced lateral expansion (inflation).

An air outlet 20a is provided on the peripheral wall of the air pipe 20, and the tubular film F1 is opened from the air outlet 20a.
The resin is cooled by the air blown into it, and the internal pressure of the hollow portion f in the tubular film F1 is increased even slightly, so that each of the disc-shaped guide members 21.
It is designed to reduce the contact resistance with.

Further, the wrinkle-stretching guide member 3 is a wrinkle-stretching member for flatly pushing open the tubular film F1 formed into a predetermined diameter as described above in the axial direction of the nip roll 4. In the embodiment, the uppermost disc-shaped guide member 21 is composed of two antennal tension members 30 whose lower ends are fixed to the upper surface. That is, the antenna-shaped tension member 30 is formed of a flexible material in a tapered shape, and the antenna-shaped tension member 30 and the antenna-shaped tension member 30 have an inversely widened shape such that the distance between the antenna-shaped tension members 30 and 30 gradually increases toward the tip. And is formed so that the spreading direction thereof coincides with the axial direction of the nip roll 4.

Therefore, the tubular film stretched and formed into a cylindrical shape having a predetermined diameter by the stretching guide member 2 is gradually spread into a flat shape by the antennal tension members 30 and 30 and a required tension is applied in the width direction. Since it is wound up on the nip roll 4 in this state, it is wound up without wrinkles.

In this embodiment, a large number of holes are formed on the entire surface of the tubular film during the molding process of the tubular film by utilizing the foaming action of the foaming agent mixed in the raw material.

As described above, in the method for forming the tubular perforated film of the present embodiment, in the tubular guide film F1 extruded from the mold 1, the guide member for stretching is in contact with the inner surface side of the tubular film F1. By expanding the film to a predetermined diameter by 2, it becomes possible to perform inflation molding of the tubular perforated film.

In addition, as described above, the tubular film F1 enlarged to a predetermined diameter is provided with a guide member 3 for wrinkle extension that contacts the inner surface side thereof.
Thus, the nip roll 4 is pushed and opened flat in the axial direction, so that the nip roll 4 can be continuously wound up without wrinkles.

Further, in the embodiment, a large number of disc-shaped guide members 21 are used as the stretching guide member 2 and two antennal tension members 30 are used as the wrinkle-stretching guide member 3, whereby a tubular film is obtained. The contact area with
The work of starting the tubular film at the start of molding can be easily performed.

Although the embodiment of the present invention has been described in detail above with reference to the drawings, the specific method and the specific configuration of members and devices used in this method are not limited to this embodiment, and the gist of the present invention Even if the specific method is changed within the range not deviating from the above, the present invention is included.

For example, in the examples, the case where the foaming agent is used as the perforating means for the tubular film is shown, but the perforating means is optional.

Further, in the examples, the case where a large number of disc-shaped guide members are used as the stretching guide member is shown, but it is also possible to use an inverted conical tubular body, in short, on the inner surface side of the tubular film. It is sufficient that the diameter can be expanded by contact.

Further, in the embodiment, the case where the two antennal tension members are used as the guide member for wrinkle straightening is shown, but in addition to that, the cylindrical body is crushed so as to be gradually flattened toward the upper end thereof. Alternatively, the disc-shaped guide member and the plate-shaped member may be connected by an elliptical guide member whose frequency is changed little by little, and the point is to contact the inner surface side of the tubular film. As a result, the tubular film may be flatly pushed open in the axial direction of the nip roll.

(Effects of the Invention) As described above, in the method for forming a tubular perforated film of the present invention, the tubular film extruded from the mold is in contact with the inner surface of the tubular film, and from the bottom to the top. Inflation of a tubular perforated film is possible by expanding from a small-diameter tubular film to a predetermined diameter by a large number of drawing guide members formed so that the diameter gradually increases toward become.

Further, since the molding is performed while blowing air into the interior, the cooling rate of the resin can be increased and the productivity can be improved, and the air can reduce the contact resistance with the drawing guide member. Therefore, it is possible to prevent the tubular perforated film from being damaged.

Further, as described above, the tubular film expanded to a predetermined diameter is pushed flat toward the axial direction of the nip roll by the wrinkle-stretching guide member that is in contact with the inner surface of the tubular film. The effect of being able to continuously wind up is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory view showing a main part of a molding apparatus used in an embodiment of the present invention, FIG. 2 is a sectional explanatory view of a mold part, and FIG. 3 is an overall view of the molding apparatus. 1: Mold 2: Guide member for stretching 3: Guide member for flattening wrinkles 4: Nip roll F1: Cylindrical film

Claims (1)

[Claims] 1. A method for forming a tubular perforated film, wherein a hole is opened in a tubular film in the middle of the process from being extruded into a tubular shape from a die until reaching a nip roll, which is extruded from the die. The tubular film having a small diameter is in contact with the inner surface side of the tubular film while blowing air into the tubular film and has a large number of drawing guide members formed so that the diameter gradually increases from the lower side to the upper side. After gradually expanding from the film-shaped film to a predetermined diameter, a wrinkle-stretching guide member that is also in contact with the inner surface of the tubular film is used to push and open it flat in the axial direction of the nip roll. A method for forming a tubular perforated film.