JPH0365780B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an inflation film forming method that reduces differences in mechanical properties such as longitudinal and transverse mechanical properties, such as tensile strength and tear strength, and uneven thickness. When forming a inflation film by expanding a thermoplastic synthetic resin tubular body melt-extruded from an annular die by the inflation method, a large number of tubes are applied to the inner surface of the tubular body immediately before the expansion starts. Inflation characterized by being inflated while in contact with a stable body, which has a cylindrical shape coaxial with the die with filamentous bodies, and each filamentous body is slightly inclined along the traveling direction of the tubular body. This relates to a film forming method.

[Prior Art] and [Problems to be Solved by the Invention] When manufacturing a film from a thermoplastic linear polymer resin by the inflation method, it takes a long time before the molten resin is extruded from a die and solidified. Although it is desirable to prevent molecular orientation and uneven thickness caused by flow of the resin or deformation due to stretching, etc., in reality, conventional inflation methods that do not utilize the above-mentioned inclined linear bodies Due to its characteristics, the orientation in the vertical direction is much larger than that in the horizontal direction, and uneven thickness also occurs.

In other words, it was an important issue and the greatest desire to obtain a material with good balance in longitudinal and lateral orientation and less uneven thickness.

[Means to solve the problem]

In the present invention, when forming a blown film by expanding a thermoplastic synthetic resin tubular body melt-extruded from an annular die by the inflation method, a large number of lines are formed on the inner surface of the tubular body immediately before the expansion starts. The gist is that the filament is inflated while being in contact with a stable body that has a cylindrical shape that is coaxial with the die, and each of the filament bodies is slightly inclined along the direction of travel of the tubular body. This is an attempt to meet the above demands.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, a large wheel 3 having a boss 2 around a shaft hole 1 will be described.
and a small wheel 6 having a boss 5 around the shaft hole 4 are rotatably and slidably attached to one support shaft 7,
A large number of long coil spring filaments 8 are stretched around the entire circumference between the outer peripheries of these large wheels 3 and small wheels 6 at predetermined intervals, and the distance and twist angle between the large wheels 3 and small wheels 6 are adjusted. By fixing the bosses 2 and 5 to the support shaft 7 with screws 9 and 9' in a non-rotatable and non-slidable manner,
A bubble stabilizer 10 is constructed in which each filament 8 is slightly inclined in the circumferential direction, and this bubble stabilizer 10 is vertically disposed at the center of a die 11 in such a direction that the large ring 3 is farther away from the die 11.

Next, the molten tubular body 13 of polyolefin resin is extruded from the die 11.
The lower end of the melting tubular body 13 is sandwiched between pinch rolls (not shown), and air is introduced into the melting tubular body 13 through the outlet 11'.
The inflation film is formed by feeding the film further to inflate it to a predetermined size and continuously winding up the film after passing through pinch rolls.

That is, in the above embodiment, the inner surface of the portion 16 of the bubble 14 just before transitioning to the funnel-shaped enlarged portion 15 is brought into soft contact with the filament 8 of the bubble stabilizer 10 when forming the blown film. Therefore, the molten linear polymer resin that has reached the above-mentioned point 16 is slid diagonally and kneaded, and by this kneading, the horizontal and vertical orientations of the linear polymer resin are changed. While making the orientation more balanced and making the thicker and thinner parts even in thickness by sliding in the same diagonal direction, it is transferred to the enlarged part 15 and stretched in the horizontal and vertical directions. It was designed to do so.

[Effect]

In the present invention, when forming a blown film by expanding a thermoplastic synthetic resin tubular body melt-extruded from an annular die by the inflation method, a large number of lines are formed on the inner surface of the tubular body immediately before the expansion starts. It is characterized by being expanded while being in contact with a stable body that is configured with strips in a cylindrical shape coaxial with the die, and each stripe is slightly inclined along the traveling direction of the tubular body. By kneading and sliding, the horizontal and vertical orientation of the linear polymer is balanced and the resin wall thickness is evened out, while the air pressure inside the valve and the tensile force due to winding are adjusted. In other words, it is possible to produce a film that has a well-balanced strength in the transverse direction and the longitudinal direction and has less uneven thickness.

〔Effect of the invention〕

As described above, the present invention makes it possible to produce a film with less difference in mechanical properties in the longitudinal and transverse directions, such as tensile strength and tear strength, and with less uneven thickness, and achieves the intended purpose. It has excellent effects that can be fully achieved.

Incidentally, in the present invention, a wire, a filament made of a hard synthetic resin material, or the like may be used as the filament.

[Brief explanation of drawings]

The figures show an embodiment of the blown film forming method of the present invention, in which Fig. 1 is a schematic diagram of the blown film forming apparatus used in the present invention, and Fig. 2 is a schematic diagram of the blown film forming apparatus used in this invention. FIG. 3 is a developed view of a portion sandwiched between lines B--B and B'--B' in FIG. 1. 1...Shaft hole, 2...Boss, 3...Large ring, 4...
Shaft hole, 5...Boss, 6...Small wheel, 7...Spindle, 8
...striate body, 9,9'...screw, 10...bubble stabilizer, 11...dice, 13...molten tubular body,
14... Bubble, 15... Funnel-shaped expansion part, 16...
...On the verge of this, 17...Cooling air ring.

Claims (1)

[Claims] 1. When forming a inflation film by expanding a thermoplastic synthetic resin tubular body melt-extruded from an annular die by the inflation method, a large number of filaments are formed on the inner surface of the tubular body immediately before the expansion starts. An inflation film forming method characterized in that the film is inflated while being in contact with a stable body formed into a cylindrical shape coaxial with a die, and each filament body is configured to be slightly inclined along the traveling direction of the tubular body. .