JPS6127239A - Cooling ring used for production of inflation film - Google Patents

Abstract

PURPOSE:To prevent a melted tube from jamming to a ring inner wall in a cooling ring even when the speed of the melted tube discharged is increased, by using a cooling ring having two annular air outlets comprising an annular air rectifying volute chamber and a special lip shape. CONSTITUTION:The present cooling ring consists of an annular air rectifying volute chamber 3, a lower annular outlet defined by a lower lip 4 opposed to an extruction die 1, an intermediate lip 5 arranged over it, and an upper annular air outlet defined by the intermediate lip 5 and an upper lip 6 arranged over it. The includes angles alpha, beta and gamma of the lips should satisfy simultaneously the relationships respectively: 5<=alpha<=30, 5<beta<=45, and 5<=gamma<=30 wherein beta>alpha and beta> gamma, alpha stands for the included angle of the lower lip, beta the included angle of the intermediate lip, and gamma the included angle of the upper lip. Accordingly, since the Venturi effect produced by the cooling air stream blown from the upper annular air outlet becomes great, the melted tube is diametrically outwardly expanded by the negative pressure and is positively supported and secured.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides a cooling ring having one annular air rectifying volute chamber and two annular air outlets connected thereto, for producing a blown film of thermoplastic resin. This is related to the improvement of. More specifically, even if the speed of the molten tube discharged from the extrusion die increases, the molten tube may get caught on the inner wall of the ring or become clogged within the cooling ring and not be cut, or the cooling air may not be blown out from the cooling ring. Occasionally,
Even if the blowing speed of the cooling air increases, the melting tube may be crushed or swayed up and down due to the influence of the pressure.
The present invention relates to a cooling ring that allows stable film production at high speed without vibration.

[Conventional technology]

A cooling ring having one annular air rectifying volute chamber and two annular air outlet ports connected to the annular air rectifying vortex chamber is, for example, disclosed in Japanese Patent Publication No. 57
-26206, in which the gap between the upper and lower annular air outlets can be finely and steplessly adjusted during film production, or a film as described in Japanese Patent Publication No. 59-23269. Some devices are known in which the gap between only the upper annular air outlet can be adjusted steplessly during manufacturing.

However, these known devices are not completely satisfactory both technically and economically, and have not yet reached the level where films can be produced stably at high speed. [Problems] Japanese Patent Publication No. 57-26206 The cooling ring described in the above issue directs the lower cooling air flow at an angle of approximately 5° to 8° radially inward of the extrusion die relative to the extrusion direction, and directs the upper cooling air flow relative to the extrusion direction. The molten tube is cooled by colliding the lower cooling air flow and the upper cooling air flow at an angle of 75° to 90' to generate a vortex. However, unless the gap between the upper annular air outlet and the lower annular air outlet is adjusted every time the film production speed changes, the Venturi action occurring within the cooling ring will not be constant, making it impossible to stably produce the film. Further, as shown in FIG. 2, the lip opening angle of the lower lip 4 is Oo1, and when the speed of the molten tube 2 discharged from the extrusion die 1 increases, the molten tip 2
If it gets caught or gets stuck on the inner wall of the lower lip 4, it will not be possible to cut the film stably at high speed.
It has the disadvantage of being

Further, the cooling ring described in Japanese Patent Publication No. 59-23269 is formed so that the outer diameter of the intermediate lip 5 and the inner wall of the upper lip 6 gradually increase in diameter, as shown in FIG. The cooling air flow blown out from the upper air outlet 8 is directed outward in the radial direction of the extrusion die with respect to the extrusion direction, and is discharged from the extrusion die 1.

When the speed of the melting tube 2 is increased, it is necessary to increase the speed of the cooling air blown out from the cooling ring, but at this time, the cooling air flow blown out from the upper blowout port 8 is directed in the extrusion direction. On the other hand, since the melting tube 2 is directed outward in the radial direction, it should be stable without being directly hit by the cooling airflow, but it is affected by the turbulence of the cooling airflow blown out from the lower blowing lower. This has the disadvantage that stable film production cannot be achieved at low speeds.

The inventor of the present invention has conducted extensive research to overcome the drawbacks of conventional devices, and has found that by using a cooling ring having one annular air rectifying vortex chamber and two annular air outlets each having a specific lip shape, Even if the speed of the molten tube discharged from the extrusion die increases, the molten tube may get caught on the inner wall of the ring in the cooling ring, become clogged and not cut, or the cooling air may not be blown from the cooling ring. When discharging the cooling air, the molten tube was crushed and swung up and down due to the pressure even though the blowing speed of the cooling air increased.
The present invention was completed by discovering that film can be manufactured stably at high speed without any movement.

〔composition〕

That is, the present invention provides an annular air rectifying volute chamber with a volume of The opening angle of each lip (in the radial direction of the extrusion die relative to the extrusion direction, Angle) In a cooling ring for producing a blown film in which α, β, and r are formed so as to simultaneously satisfy the formulas 5≦α≦30.5<β≦45, 5≦r≦30, β>α, and β〉
- It is a cooling ring characterized by being r.

However, α: Opening angle of the lower lip (') β: Opening angle of the middle lip (0) r: Opening angle of the upper lip (0) In the cooling ring of the present invention, the opening angle of each lip is specified in the above relationship. This was done in order to provide stable running of the molten tube, and in particular, by setting β>α and β>a, the speed of the cooling air blown out from the lower annular air outlet increases, causing In the space formed by the intermediate lip and the melting tube in the intermediate lip portion, the speed is gradually reduced, so it is extremely rare for the melting tube to be crushed or vibrated up and down, and the annular blowout on the father's upper part is extremely rare. The Venturi effect generated by the cooling air flow blown out from the outlet is also greatly increased, so the molten tube is pulled radially outward by the negative pressure and is strongly supported and fixed, allowing the film to be formed stably at high speed. This is because it can be manufactured.

In addition, the shape of the lower lip is determined by the following formula: DO+10≦Dt,≦DO+30 5≦H≦25 50≦α≦25″ However, DL: Extrusion die side lip diameter (Tom) DO:
# Output die diameter (tomo) H : Lip extrusion direction sieve (tomo) α = lip opening angle (0) The cooling ring is formed so as to simultaneously satisfy the following conditions:
When increasing the speed of the molten tube discharged from the extrusion die (increasing production volume), this prevents the molten tube from sticking to the inner wall of the lip at the lower lip, or from clogging and cutting. This method is particularly preferable because the film can be produced stably at high speed.

Practically, the opening angle of each lip is determined by the formula, io'≦α≦
It is preferable to simultaneously satisfy 25°, 10°<β≦40°, and 10′≦α≦25°.

When the cooling air flow blown out from the lower annular air outlet is blown out in the radial direction of the annular die from the extrusion direction in the range of 0 to 20 degrees, the tension in the molten tube near the outlet of the annular die increases, and the cooling This is preferable because the air blowing speed can be increased.

The blowing angle of the cooling air flow blown out from the upper annular air outlet is 1/(0' to 3
A range of 0° is preferred.

The above-mentioned blowout angle can be set by a known general method. In the cooling ring of the present invention, the method for adjusting the gap between the upper and lower annular outlets does not need to be limited to <K. It is also preferable that the gap between only the upper annular air outlet can be adjusted steplessly.

Further, the interval between the upper annular outlet and the lower annular outlet is generally 30 to 35,011 mm.

A mist may be used for the cooling air to increase the cooling capacity.

An overview of one practical aspect of the present invention is shown in FIG.

FIG. 1 is a cross-sectional view of a cooling ring whose gap can be adjusted steplessly only at the upper annular air outlet during film production.
It is precooled by the cooling air blown out from the lower annular air blowing lower, which is composed of a lower lip 4 having a diameter Dbs opening angle α, a height H, and an intermediate lip 5 having a lip opening angle β, and then, Main cooling is performed by the cooling air blown out from the upper annular air outlet 8, which is composed of an intermediate lip 5 having a lip opening angle β and an upper lip 6 having a lip opening angle r.

At this time, due to the Venturi effect of the cooling air flow blown out from the upper annular air outlet 8, the molten tube 2 is pulled radially outward by the negative pressure and is strongly supported and fixed, and its thickness is rapidly reduced. A frost line is formed and cooling is completed.

Further, the cooling air rectified in the annular air rectification overwinding chamber 3 is branched into an upper annular air outlet 8 and a lower annular air outlet.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Linear low density I-lyethylene (Santic LL.

Using LP'2408 (no chemical conversion), a molten tube was discharged from an annular die with a diameter of 100 mm and a die gap of 2 ws using a 50 mm extruder, and a cooling ring with dimensions shown in Table 1 was used to extrude the molten tube. An inflated Silon film was produced under the conditions shown in Table 2, and the film was produced with a stable Taka%.

Here, e is the blowing angle (inward angle in the radial direction of the extrusion die with respect to the extrusion direction) of the cooling air flow blown out from the lower annular air outlet, It is the blowing angle of the cooling air flow (the blowing angle according to the same constant @ as e).

Table 2 Example 2 A film was produced using a cooling ring under the same conditions as Example 1, except that the value of ε was Oe.With stable production, the maximum discharge amount that could be achieved was 42, and the 2/H1 take-up speed was 315 m. /-
Met.

Comparative Example 1 A film was produced under the same conditions as Example 1, but using a cooling ring as shown in Table 3. The maximum discharge amount that could be stably produced was 30 1/H1 and the take-up speed was 2 x 5 m/m.
Met.

Table 3 Comparative Example 2 When a film was manufactured under the same conditions as Example 1, but using a cooling ring as shown in Table 4, the maximum discharge amount that could be stably manufactured was 20 KP/H%, and the take-up speed was 146 @
-/m.

Table 4 [Effects] The cooling ring of the present invention has one annular air rectifying volute chamber and two annular air outlets connected to the annular air outlet having a specific shape, but the opening angle of each lip etc. By taking a specific relationship, even if the speed of the cooling air blown out from the lower annular air outlet increases, it is gradually decelerated in the space formed by the middle lip and the melting tube. Therefore, the molten tube is extremely unlikely to be crushed or shaken up and down, and the pentier effect generated by the cooling air flow blown out from the upper annular outlet is also much larger. Therefore, the molten tube is pulled outward in the radial direction by the negative pressure and is strongly supported and fixed, so that films can be produced stably at high speed, so it has great industrial utility value.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, and FIGS. 2 and 3 are sectional views of a conventional cooling ring in use. In the figure, l is an extrusion die, 2 is a melting tube, 3 is an annular air rectifying vortex chamber, 4 is a lower lip, 5 is an intermediate lip, 6 is an upper lip, 7 is a lower annular air outlet, 8 is an upper annular air outlet Outlet, DO is the extrusion die diameter, DL is the extrusion die side diameter of the lower lip, H is the height of the lower lip in the extrusion direction, α is the opening angle of the lower lip, β is the opening/negative angle of the intermediate lip, r#
'i The opening angle of the upper lip, ε, is the blowing angle of the cooling air stream blown out from the lower annular air outlet, and δ is the blowing angle of the cooling air stream blown out from the upper annular air outlet. Patent applicant Asahi Kasei Kogyo Co., Ltd. Figure 2 Figure 2
No. 2 Name of the invention Cooling ring for manufacturing blown film a Relationship with the case of the person making the amendment Patent applicant 1-2-6 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture "Scope of claims" of the specification to be amended and "Detailed description of the invention"
Column /-1 ＼ 7.44 Fraud ＼ 5. Contents of amendment (1) The scope of claims in the specification will be corrected in the attached document. (3) Correct page 4, line 16, “about 5° to 8°” to “about 5° to oOJ.” (3) Page 6, line 1θ, “result, one ring” to “result,
Tamaki,” he corrected. (4) Line 9, line 19 "Range of 0° to 30'"
is corrected to "in the range of -30° to 30°." (5) Same No. 13jr Table 2 1'-BVRJ to rBURJ
I am corrected. (6) In the seventh line from the bottom of page 15, ``The cooling ring of the present invention is annular'' is corrected to ``The cooling ring of the present invention is annular.'' Claim L: An annular air rectifying volute chamber, a lower lip facing the extrusion die, an intermediate lip disposed above the extrusion die, a lower annular air outlet configured by them, and the intermediate lip and the intermediate lip. It consists of an upper lip disposed above and an upper annular air outlet formed by the upper lip, and the opening angle of each lip (the angle outward in the radial direction of the extrusion die with respect to the extrusion direction) α, β, and T are A cooling ring for producing a blown film formed to simultaneously satisfy the following formulas: S≦α≦30.5<β≦45.5≦r≦30, characterized in that β>a and β>γ. Cooling ring where: α: Opening angle of the lower lip (0) β: Opening angle of the middle lip (0) r: Opening angle of the upper lip (0) Claim 1 characterized in that it is formed in
Cooling ring D described in section. +10≦DL≦DO+30 5≦H≦25 1O≦α≦25 However, DL@lower lip extrusion die side lip diameter (tomo)
:Extrusion die diameter (,1):Lip extrusion direction height (Q):Lip opening angle (0)λ A patent characterized in that the opening angle of each lip is formed so as to simultaneously satisfy the following formula: Cooling ring lO≦α≦25.10<β≦40.10≦γ≦25 according to claim 1 or 2
The cooling air flow blown out from the lower annular air outlet is in the range of 06 to 20 degrees inward in the radial direction of the extrusion die with respect to the extrusion direction, and the cooling air flow blown out from the upper annular air outlet is in the range of 06 to 20 degrees inward in the extrusion die radial direction with respect to the extrusion direction. The cooling ring according to any one of claims 1, 2, and 3, characterized in that it is formed to blow out inward in the radial direction of the extrusion die in a range of 130° to 30″.

Claims (1)

[Claims] 1. An annular air rectifying volute chamber, a lower lip facing the extrusion die, an intermediate lip disposed above the extrusion die, a lower annular air outlet constituted by them, and the intermediate lip and its intermediate lip. It consists of an upper lip disposed above and an upper annular air outlet formed by the upper lip, and the opening angle of each lip (the angle outward in the radial direction of the extrusion die with respect to the extrusion direction) α, β, and γ are In a cooling ring for blown film production that is formed to simultaneously satisfy the following formulas: 5≦α≦30, 5<β≦45, 5≦γ≦30, β>α and β>γ. A cooling ring characterized by: α: Opening angle of the lower lip (°) β: Opening angle of the middle lip (°) γ: Opening angle of the upper lip (°) Claim 1 characterized in that:
Cooling ring D_O+10≦D_L≦D_O+30 5≦H≦25 10≦α≦25 However, D_L: Extrusion die side lip diameter of lower lip (m
m) D_O: Extrusion die diameter (mm) H: Lip extrusion direction height (mm) α: Lip opening angle (°) 3. The opening angle of each lip must be formed so as to simultaneously satisfy the following formula. Cooling ring 10≦α≦25, 10<β≦40, 10≦γ≦254 according to claim 1 or 2, characterized in that the cooling air flow blown from the lower annular air outlet is The cooling air flow blown out from the upper annular air outlet is in the range of 0° to 20° radially inward of the extrusion die with respect to the extrusion direction, and the cooling air flow blown out from the upper annular air outlet is 0° to 3° radially inward of the extrusion die with respect to the extrusion direction.
The cooling ring according to any one of claims 1, 2, and 3, characterized in that the cooling ring is formed to blow air in a range of 0°.