JPH0535253U - Inflation film forming equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] It is an object of the present invention to provide a molding apparatus in which a molten resin does not adhere to the surface of an inflation film stabilizer when molding a linear low density polyethylene by a long neck molding method. To do. A device for forming an inflation film, characterized in that a spring 12 is provided on the surface of an inflation bubble stabilizer 9 so as to be rotatable in a direction in which a bubble lower portion 15 is taken out.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention particularly relates to a blown film molding apparatus (hereinafter, simply referred to as a molding apparatus) that enables linear low density polyethylene (L-LDPE) to be molded by a so-called long neck molding method. .

[0002]

[Prior Art]

 There is a so-called long neck method as a method for producing an inflation film having excellent strength. FIG. 6 is a schematic view showing a main part of a conventional molding apparatus for carrying out this long neck method.

This molding apparatus includes a die 13, a stabilizer 9, and a column 10. A column 10 is attached to the die 13. Air is supplied to the column 10 so as to blow out from a tip portion 14 (hereinafter referred to as a gas blowout port). Then, the molten resin 15 (hereinafter, referred to as a bubble lower portion) extruded in a tubular shape from the die 13 is expanded to a predetermined size by the air blown from the column 10 and then taken toward the winder 4. Will be taken.

As shown in FIG. 7, a columnar stabilizer 9 is attached to the pillar 10. The lower portion 15 of the bubble extruded from the die 13 is supported by the stabilizer 9. The surface of the stabilizer 9 was covered with a slippery cloth (rasha) or finished to be smooth so that the friction with the lower portion 15 of the bubble was reduced.

When molding is performed using such a molding device, if the bubble lower part 15 is in contact with the stabilizer 9, the molding becomes impossible. Therefore, various measures have been taken to prevent this. For example, Japanese Patent Publication No. 57-201330 proposes to form the surface of the stabilizer 9 with a material having a small thermal conductivity. As described above, when the surface of the stabilizer 9 is formed of a material having a low thermal conductivity, it is possible to prevent the lower portion 15 of the bubble from solidifying while being in contact with the stabilizer 9, so Adhesion can be avoided.

[0006]

[Problems to be solved by the device]

 By the way, the conventional molding apparatus as described above was developed for molding high-density polyethylene having a large elasticity in a molten state. When a resin such as L-LDPE having a small elasticity in a molten state (a small melt tension) and a high adhesiveness in a molten state is molded by using the conventional molding apparatus, a bubble extruded from the die 13 is pressed. Since the lower part 15 adheres to the surface of the stabilizer 9, it is impossible to mold L-LDPE with the conventional molding device. The present invention has been made in view of the above circumstances, and an apparatus for forming an inflation film in which the bubble lower portion 15 does not adhere to the surface of the stabilizer 9 even when the L-LDPE is formed by the long neck forming method. The purpose is to provide.

[0007]

[Means for Solving the Problems]

 In the molding apparatus of the present invention, the above problem is solved by providing a rotating member, which is rotatable in the direction in which the extruded molten resin is drawn, on the surface of the stabilizer.

[0008]

[Action]

 In the molding apparatus of the present invention, since the rotating member that is rotatable in the direction in which the molten resin extruded from the die is taken out is projected on the surface of the stabilizer, the molten resin extruded from the die and the surface of the stabilizer 9 are separated from each other. The contact area is reduced, and the friction between the two is reduced. Further, if the friction between the rotating member and the molten resin increases to some extent, the rotating member rotates in the direction in which the molten resin is taken off, so that an increase in the friction between the two can be instantaneously avoided.

[0009]

【Example】

 Hereinafter, the molding apparatus of the present invention will be described in detail with reference to the drawings. The same components as those of the conventional example are designated by the same reference numerals to simplify the description.

Example 1 FIG. 1 is a diagram showing a portion of a stabilizer 9 of a molding apparatus of this example. Four grooves 16 having a semicircular cross section are formed on the surface of the stabilizer 9. The groove 16 is formed in the circumferential direction of the stabilizer 9. A spring 12 is fitted in the groove 16 as a rotating member. The spring 12 is formed into an annular shape by connecting both ends, and is accommodated with a slight margin with respect to the groove 16. By thus holding the spring 12 with a slight allowance, the spring 12 is allowed to rotate in the take-up direction of the bubble lower portion 15.

In the molding apparatus equipped with such a stabilizer 9, when molten resin is extruded from the die 13, the bubble lower portion 15 is the outermost portion of the spring 12 of the stabilizer 9 (hereinafter abbreviated as apex). ), While moving upward. At this time, if the friction between the bubble lower portion 15 and the spring 12 increases to some extent, the spring 12 rotates in the direction in which the bubble lower portion 15 is taken out, and the increase in friction between them is instantaneously avoided.

In the molding apparatus of this embodiment, a spring 12 that is rotatable in the direction in which the lower portion 15 of the bubble is pulled out is provided on the surface of the stabilizer 9. Therefore, in this forming apparatus, the bubble lower portion 15 extruded from the die 13 is supported by the apex of the spring 12 and ascends, and the area where the bubble lower portion 15 and the stabilizer 9 contact each other becomes small, Friction between the lower portion 15 of the bubble and the stabilizer 9 is reduced. Further, the bubble lower part 15 pushed out from the die 13 is pulled upward while being in contact with the apex of the spring 12, but if the resistance between the spring 12 and the bubble lower part 15 increases during this period, the spring 12 will be broken. The lower part 15 of the bubble rotates in the pulling direction, and the rotation of this spring 12 immediately avoids an increase in the friction between the lower part 15 of the bubble and the stabilizer 9. Therefore, in the molding apparatus of this embodiment, it is possible to carry out inflation molding even with a resin having a low melt tension and a high tackiness in a molten state such as L-LDPE.

Example 2 FIG. 2 is a diagram showing a part of a stabilizer 9 of a molding apparatus of this example. The difference between the molding apparatus of this embodiment and that shown in Embodiment 1 is that balls 17 are used as the rotating member. As shown in FIG. 3, the balls 17 are rotatably held at regular intervals by a ball retainer 18 used in a single-axis radial ball bearing or the like.

Also in the molding apparatus of this embodiment, the same operational effect as in Embodiment 1 was obtained.

(Embodiment 3) FIG. 4 is a view showing a portion of a stabilizer 9 of a molding apparatus of this embodiment. Grooves 16 are spirally formed on the surface of the stabilizer 9 of the molding apparatus of this embodiment. A ball 17 connected by a ball holder 18 is attached to the groove 16.

Also in the molding apparatus of this example, the same operation and effect as in Example 1 were obtained.

(Embodiment 4) FIG. 5 is a cross-sectional view showing a portion of a stabilizer 9 of a molding apparatus of this embodiment. The difference between the stabilizer 9 of the molding apparatus of the present embodiment and that of the first embodiment is that the ball 16 first rotatably held by the ball cage 18 in the groove 16 formed on the surface of the stabilizer 9. 17 is attached, and the spring 12 is further attached on it.

In the molding apparatus of this embodiment, the ball 17 is provided inside and the spring 12 is supported thereby, so that the spring 12 can easily rotate. Therefore, according to the molding apparatus of this embodiment, there is an advantage that the effect of avoiding an increase in friction between the bubble lower portion 15 and the spring 12 is improved.

[Effect of the device]

 As described above, in the blown film forming apparatus of the present invention, since the rotary member that is rotatable in the direction in which the molten resin is taken out is projected on the surface of the inflation bubble stabilizer, the molten resin is stabilized. It is in a state of being supported by the rotating member projecting on the, and the contact area between them becomes small. As a result, friction between the molten resin and the blown film stabilizer is reduced. Further, if the resistance between the rotating member and the molten resin increases to some extent, the rotating member rotates in the direction in which the molten resin is taken out. By this rotation, an increase in friction between the molten resin and the inflation film stabilizer is instantaneously avoided. Therefore, according to the inflation film forming apparatus of the present invention, an inflation film can be formed even with a resin such as L-LDPE having a low melt tension and a high adhesiveness in a molten state.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a portion of a stabilizer of a molding apparatus according to a first embodiment.

FIG. 2 is a partial cross-sectional view showing a portion of a stabilizer of a molding apparatus according to a second embodiment.

FIG. 3 is a front view showing a ball attached to the surface of a stabilizer of the molding apparatus of Example 2;

FIG. 4 is a partial cross-sectional view showing a portion of a stabilizer of a molding apparatus according to a third embodiment.

FIG. 5 is a transverse cross-sectional view showing a portion of a rotary member of the molding apparatus of Example 4.

FIG. 6 is a schematic view showing a main part of a conventional molding apparatus.

FIG. 7 is a schematic view showing a stabilizer of a conventional molding apparatus.

[Explanation of symbols]

 9 Blown film stabilizer 10 Struts 12 Spring 13 Dice 15 Bubble bottom 17 Balls

Claims (1)

[Scope of utility model registration request] 1. An apparatus for forming an inflation film, comprising an inflation bubble stabilizer for supporting a molten resin extruded in a tubular shape from an extruder and attached to a die, wherein the surface of the inflation bubble stabilizer receives the molten resin. An inflation film forming apparatus, wherein a rotating member rotatable in a predetermined direction is provided so as to project.