JPH0532210B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field] The present invention relates to a sheet extrusion molding device for molding a polymer into a film or a plate (hereinafter referred to as a sheet), and further relates to Specifically, the present invention relates to an improvement in a sheet extrusion molding apparatus that allows adjustment of the thickness profile of the sheet in the width direction.

[Prior Art] Generally, the thickness of a sheet-like material is required to be uniform depending on its intended use, and in order to achieve this, many ideas have been proposed to make the discharge amount uniform in the width direction of the die of a molding device. has been done.

These ideas can be roughly divided into two methods: one is to adjust the distance between the slits in the discharge part of the nozzle, the other is to locally change the temperature in the width direction of the nozzle to locally change the viscosity of the extruded polymer, thereby changing the flow state. The method is summarized into two methods: a method in which the discharge amount in the width direction of the mouthpiece is controlled by changing the amount, and the latter method is attracting attention as a method that can achieve a particularly precise thickness profile.

The latter method for adjusting the temperature in the width direction of the cap includes, for example, the method disclosed in Japanese Patent Publication No. 57-59050 or Japanese Patent Publication No. 57-59051. These systems, which are typified by Japanese Patent Publication No. 57-59050, are more efficient in the vicinity of the discharge part than the systems using only an auxiliary heating device disclosed in, for example, Japanese Patent Publication No. 57-1409 and Japanese Patent Publication No. 56-3170. By adding a cooling device that can forcibly cool the
It is possible to keep the temperature in the vicinity of the mouthpiece discharge portion low due to the heating amount of the auxiliary heating device.

That is, when the amount of thickness adjustment is constant, the amount of temperature change at the discharge portion of the die required to adjust the thickness will be approximately constant if the extruded material is the same. Therefore, when adjusting only by heating means and when adjusting by both heating and cooling means, it is naturally possible to adjust the absolute value of the temperature on the lower side in the latter case. .

Therefore, the 1986 special public service that does not have the above-mentioned cooling device
The problem of thermal distortion of the nozzle discharge part that occurs in the molding apparatus described in Publication No. 3170 can be solved by using a cooling device that forcibly cools the vicinity of the discharge part, as proposed in Japanese Patent Publication No. 57-59050. The additional molding equipment will reduce this.

[Problems to be Solved by the Invention] However, the conventional devices described in the above-mentioned Japanese Patent Publication No. 50-59050 and Japanese Patent Publication No. 57-59051,
When the heat medium is a liquid, the lip is directly forcedly cooled, which has the disadvantage that the cooling effect on the lip is too large, resulting in temperature unevenness in the width direction, and it is difficult to obtain a sheet-like material with a uniform thickness in the width direction. The drawbacks were that a cooling device with a complicated structure including multiple closed loops for liquid circulation was required as many sections as necessary for thickness adjustment, and a considerable amount of space and equipment cost were required.

On the other hand, if the heating medium is a gas, there is no need to provide a closed loop, and it can be released into the outside air, for example, if air is used as the heating medium, the space will be small and the investment cost will be advantageous. , the cooling air is discharged near the nozzle discharge section, which greatly disturbs the airflow near the nozzle discharge section.

Therefore, if the viscosity of the molten material is low when it is discharged, vibrations due to the turbulence of the airflow of the discharged sheet of molten material will occur near the discharge portion, resulting in new thickness unevenness.

As described above, the conventionally proposed method of adjusting the thickness of a sheet material by changing the temperature in the width direction of the die and adjusting the amount of extruded material discharged from the die in the width direction of the die is in principle. Although it is excellent, there are still many problems in its practical use.

The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art in the method of controlling the thickness in the width direction of a sheet-like object formed from an extruded material by adjusting the temperature in the width direction of the die, and in particular to solve the problem of cooling in the width direction of the sheet-like object. It eliminates the drawback of uneven thickness in the width direction of a sheet-like object caused by unevenness, makes it possible to control the thickness of the sheet-like object more uniformly in the width direction, withstands long-term operation, and is economically inexpensive. An object of the present invention is to provide an apparatus for extruding a molecular polymer sheet.

[Means for Solving the Problems] A polymer sheet extrusion molding apparatus according to the present invention for achieving the above object includes a sheet forming slit portion of a polymer sheet extrusion molding apparatus. A polymer sheet extrusion molding apparatus comprising: a pair of lip blocks to be formed; and a plurality of heat transfer bodies provided at a plurality of locations in the longitudinal direction of at least one of the pair of lip blocks, (a) The heat transfer body consists of a columnar body whose one end is a heating element having a forced heating means and the other end is a heat radiating element having a natural heat radiating means, and (b) the heating element is at least partially is inserted into the lip block, and the heat dissipation element is provided at a portion projecting outward from the lip block.

[Example] The present invention will be explained using a preferred example shown in the drawings.

The figure is a cross-sectional view of the polymer sheet extrusion molding apparatus according to the present invention, in which a melt of a polymer, for example, polyethylene terephthalate, enters the mouthpiece body 1 from arrow A and enters the mouthpiece body 1. After being widened in the width direction of the nozzle in the manifold section 2 provided in the manifold section 2, it is discharged from the slit section 3 in the direction of arrow B as a molten film or a plate. The slit portion 3 is connected to a pair of left and right lip blocks 1 forming the mouthpiece body 1.
1 and 12, and the left lip block 12 is equipped with a large number of adjustment bolts 5 in the mouth width direction for deforming the lip block 12 within an elastic deformation and manually adjusting the distance between the slits 3. The adjustment bolt 5 is used when a large thickness adjustment is required, such as when starting discharge, for example.

On the other hand, a large number of heating devices 4 are attached to the right lip block 11 in the width direction of the mouthpiece.

It goes without saying that the lip blocks 11 and 12 have sufficient mechanical strength to prevent the distance between the slit portions 3 from changing due to thermal strain stress generated inside the cap in the width direction of the cap.

In the embodiment shown in the figure, each heating device 4 includes a heat transfer body 40, a part of which is inserted into the lip block 11, and another part of which protrudes outside the lip block 11; lip block 1
Heating element 41 provided in the part located in 1
and a heat radiating element 42 provided in a portion of the heat transfer body 40 located outside the lip block 11. Further, as the heating element 41, an electric heater with a maximum capacity of 40 W is shown, and as the heat radiation element 42, a fin mechanism made of aluminum or copper is shown. In this embodiment, the connection mechanism that connects the energy supply source required for heating is the power line 43.
It is shown in It is desirable that the heating element 41 embedded in the heat transfer body in the lip block 11 be inserted as close as possible to the slit portion 3 and be spaced apart from the heat radiating element 42. In addition, the heat transfer body 40
In order to facilitate heat flow between the heating element 41 and the heat dissipation element 42, it is preferable that the heating element 41 is made of a columnar body made of a material with low heat transfer resistance such as copper or aluminum. If a heat pipe mechanism is interposed between the heat dissipation element 42 and the heat dissipation element 42, even more effects can be achieved. The heating element 41 is preferably a forced heating means, for example, a heat transfer heater, in terms of temperature controllability and compactness, but is not necessarily limited to this. For example, a known heating device such as an induction heater may be used. Needless to say, it can be effectively applied.

As mentioned above, the heating element 41 embedded in the heat transfer body in the lip block 11 is inserted as close to the slit portion 3 as possible, and the heat dissipation element 4
Although it is desirable that the heating element 41 be placed apart from the lip block 11, the heat transfer body 40 made of a material with low heat transfer resistance efficiently conducts the heat flow from the heating element 41 to the lip block 11. Even if it is provided in the heat transfer body 40 located on the outside, the initial object of the present invention can be sufficiently achieved.

Further, as the heat dissipation element 42, in addition to the fin mechanism described above, a simple rod-like structure without fins (no heating element) can be considered, but in order to increase the amount of heat dissipation, it is necessary to increase the heat dissipation area. It is preferable to have a large fin mechanism.

In the sheet extrusion molding apparatus of the present invention configured as described above, when the unevenness difference in the thickness pattern of the sheet-like object is relatively large and the pitch between the unevenness is small, the unevenness between the unevenness Temperature adjustment sections in the width direction of the cap corresponding to pitches are required, and it is necessary to provide a temperature change amount or a temperature gradient commensurate with the unevenness difference between the temperature adjustment sections in the width direction of the cap. In particular, when controlling the thickness of a thin film sheet, for example, an ultra-thin film of about 10 μm, the pitch between the unevenness of the thickness pattern is often around 10 to 20 mm, and the thickness adjustment interval corresponding to that, that is, the temperature An adjustment section is required, and the heating device for temperature adjustment is desired to be as compact as possible. However, the heating device of the present invention has a heating element and a heat radiation element integrally connected by a heat transfer member. Since it has a simple structure, it can be used to control the thickness of ultra-thin sheet materials.
They can be extremely easily arranged at desired intervals in the width direction of the cap, that is, preferably at intervals of 10 mm to 25 mm, more preferably at intervals of 15 mm to 20 mm.

The heating device arranged and configured in this way can be automatically controlled by incorporating a control device that controls the heating amount of the heating device in conjunction with a known thickness gauge (not shown) built into the sheet-like material forming machine. Can be controlled to desired thickness level.

The present inventors have designed a device for manufacturing biaxially stretched polyethylene terephthalate film, in which a 40W heating element and an aluminum fin are integrated with a heat conductor at 20mm intervals on one lip of a 750mm wide base. By arranging a heating device as shown in accordance with the spirit of the present invention and automatically controlling it in conjunction with a thickness gauge (not shown), we manufactured a 10 μm film, which achieved a thickness level of 4 to 3% compared to the conventional manual method. However, we were able to achieve a desired thickness level of 2% or less.
In addition, in the case without the fin mechanism, the thickness level did not change much even if the ON rate of the heater, which is a heating element, changed significantly, and it reached a state where automatic control was impossible.

That is, although the present invention has a simple configuration in which a heat dissipation element is attached to a heat transfer body and is simply thermally integrated with a heating element and does not actively use water, air, etc. as a heat medium, First, it is demonstrated that the temperature adjustment speed in the width direction of the mouthpiece, that is, the quick response speed, can be obtained in proportion to the change speed of the thickness pattern of the sheet material over time.

[Effects of the Invention] As described above, the polymer sheet extrusion molding apparatus according to the present invention includes a pair of lip blocks forming a sheet forming slit portion of the polymer sheet extrusion molding apparatus; A polymer sheet extrusion molding apparatus comprising: a plurality of heat transfer bodies provided at a plurality of locations in the longitudinal direction of at least one of a pair of lip blocks, (a) the heat transfer body: (b) The heating element is at least partially inserted into the lip block. In addition, since the heat dissipation element is provided in an outwardly projecting portion of the lip block, the following excellent effects can be achieved.

A: Since the device of the present invention brings the heating element of the heat transfer body into direct contact with the lip block, it not only ensures excellent response during heating, but also reduces the film thickness of the sheet material during cooling, unlike conventional devices. Rather than directly forcing the lip block to cool down, the heat radiating element installed outside the lip block cools the lip block through the columnar body by natural heat radiation, which allows for rapid cooling of the lip block at the location of each heat transfer element. The effect is eliminated.
Therefore, temperature unevenness in the width direction of the lip block is eliminated, and a sheet-like product having a uniform thickness in the width direction is obtained.

B Also, since the heat transfer body is made into a columnar body by integrating the heating element and the heat dissipation element, the structure of the heat transfer body is simplified, and the entire extrusion molding apparatus for polymer sheet material is made more compact. At the same time, an economically inexpensive device that can withstand long-term operation can be obtained.

[Brief explanation of the drawing]

The figure is a cross-sectional view showing one embodiment of a polymer sheet extrusion molding apparatus according to the present invention. Explanation of symbols in the drawings, 1...Body of the cap, 2...
Manifold part, 3... Slit part, 4... Heating device, 5... Adjustment bolt, 11, 12... Lip block, 40... Heat transfer body, 41... Heating element, 4
2... Heat dissipation element, 43... Power line.

Claims (1)

[Scope of Claims] 1. A pair of lip blocks forming a sheet forming slit portion of a polymer sheet extrusion molding apparatus, and a plurality of lip blocks provided at a plurality of locations in the longitudinal direction of at least one of the pair of lip blocks. A polymer sheet extrusion molding apparatus comprising: (a) the heat transfer body has a heating element having a forced heating means at one end and a natural heating element at the other end; It consists of a columnar body that is a heat radiating element having a heat radiating means, (b) at least a part of the heating element is inserted into the lip block, and the heat radiating element is inserted into a portion projecting outside of the lip block. 1. A high molecular weight polymer sheet extrusion molding apparatus, characterized in that: