JP2017035789A - Manufacturing method of sheet and manufacturing device of sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet manufacturing method and a manufacturing device capable of controlling variations of film thickness and physical properties generated by rolling speed variation of an extruder or a gear pump.SOLUTION: The sheet manufacturing device achieves high temporal stability of film thickness and physical properties by controlling rolling speed of an extruder and a second gear pump at constant and further controlling a first gear pump to set pressure of a sheet material at exit of the extruder at constant pressure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a sheet manufacturing method and a sheet manufacturing apparatus.

  As a general sheet manufacturing apparatus, an apparatus is known in which a sheet material (typically, a molten resin) melted by an extruder is transported by a gear pump and formed into a sheet shape by a die. Then, the formed sheet is solidified and is subjected to a post-treatment such as stretching as it is or to form a film.

  In recent years, importance has been placed on the stability of film thickness and physical properties over time due to the enhancement of film functionality and thinning. Since the extruder melts or kneads the sheet material by rotating the screw, the rotational speed of the extruder greatly affects the film physical properties. In addition, since the gear pump measures and transports the sheet material by rotating the gear, the rotation speed of the gear pump greatly affects the film thickness. On the other hand, the pressure of the sheet material at the exit of the extruder also affects the melt-kneading state in the extruder, that is, the film physical properties, and if it fluctuates, it may cause fatal problems such as vent-up and air biting. Therefore, in order to achieve both film thickness and stability over time with high physical properties, it is ideal to form a film with a constant rotational speed of the extruder and the gear pump and a constant pressure at the outlet of the extruder. However, in a general sheet manufacturing apparatus, when both the rotation speeds of the extruder and the gear pump are made constant, the pressure at the outlet of the extruder cannot be controlled and the pressure cannot be kept constant. For this reason, in general sheet manufacturing equipment, the rotational speed of either or both of the extruder and gear pump is controlled so that the pressure at the exit of the extruder is constant, and the film thickness or physical properties are stable over time. Absent. In order to solve this problem, a new technique that achieves both film thickness and stability over time with high physical properties is required.

  By the way, there is an operation control apparatus and an operation control method for a resin extrusion molding apparatus disclosed in Patent Document 1 as a technique that looks similar to a preferable embodiment of the present invention.

  Patent Document 1 discloses a control device including a gear pump in front of each filtration device for the purpose of improving operational control when two filtration devices are used. 3 and 4 are schematic views of the resin extrusion molding apparatus 102 of Patent Document 1. FIG. As shown in FIG. 3, the resin is melted by the extruder 1, transported by the first gear pump 2, transported by the second gear pump 3 via the first filtering device 6, and the second filtering device. 7 is formed into a sheet shape with a base 4. At the time of molding, the second gear pump 3 controls the rotation speed to be constant, and the extruder 1 and the first gear pump 2 have their rotation speed controlled by the control means 12 and 13 so that the pressure before the second gear pump 3 becomes constant. Control. Further, at the time of start-up and when the discharge amount is changed, as shown in FIG. 4, the first gear pump 2 and the second gear pump 3 control the rotation speed so that the respective pre-pressures become constant by the control means 11 and 14, respectively. To do. In this way, by using a control method that is different from that at the time of molding when changing the discharge amount, the stable work time until the extrusion starts stably and the molding starts is reduced, and the loss of the resin used up to that time is reduced. can do.

JP 2003-1696 A

  However, with the technique of Patent Document 1, the physical properties of the film are not stabilized because the rotational speed of the extruder 1 changes during molding, and the film thickness and the stability over time with high physical properties cannot be compatible.

  An object of the present invention is to provide a sheet manufacturing method and a manufacturing apparatus that can achieve both the film thickness and the stability over time with high physical properties.

In the sheet manufacturing method of the present invention that achieves the above object, the sheet material is melted and extruded by an extruder, the sheet material extruded from the extruder is transported by a first gear pump, and further transported from the first gear pump. A sheet material transported by a second gear pump, and the sheet material transported from the second gear pump is formed into a sheet shape with a die,
The extruder and the second gear pump are operated while controlling the rotation speed to be constant, and the pressure value of the sheet material at the outlet of the extruder is constant for the first gear pump. As described above, the motor is operated with its rotational speed controlled.

Moreover, the sheet manufacturing apparatus of the present invention that achieves the above object includes an extruder for melting the sheet material,
A first gear pump provided downstream of the extruder for transporting sheet material;
A second gear pump for transporting sheet material provided downstream of the first gear pump;
A base provided on the downstream side of the second gear pump for forming a sheet material into a sheet shape;
A pressure measuring device provided at the outlet of the extruder for measuring the pressure of the sheet material;
A control device for controlling the respective rotational speeds of the extruder, the first gear pump, and the second gear pump so that the rotational speeds of the extruder and the second gear pump are constant. And a control device for controlling the rotation speed of the first gear pump so that the pressure value of the sheet material measured by the pressure measuring device is constant.

Next, the meaning of each term in the present invention will be described.
“Sheet material” refers to a material constituting the sheet. Examples of sheet materials include polyolefin resins such as polyethylene, polypropylene, polystyrene, and polymethylpentene, alicyclic polyolefin resins, polyamide resins such as nylon 6 and nylon 66, aramid resins, polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, Polybutyl succinate, polyester resin such as polyethylene-2,6-naphthalate, polycarbonate resin, polyarylate resin, polyacetal resin, polyphenylene sulfide resin, tetrafluoroethylene resin, trifluorinated ethylene resin, trifluorinated ethylene chloride resin, Fluoropolymers such as tetrafluoroethylene-6fluoropropylene copolymer / vinylidene fluoride resin, acrylic resin, methacrylic resin, polyacetal resin , Polyglycolic acid resins, polylactic acid resins, and the like can be used as the fluidized, such as by melt or dissolved in a solvent. Further, these thermoplastic resins may be homo resins, copolymerized or blends of two or more. Also, in each thermoplastic resin, various additives such as antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, organic particles, thickeners, thermal stabilizers, lubricants, infrared absorbers, ultraviolet absorbers. An agent, a dopant for adjusting the refractive index, and the like may be added.

  “Extruder” refers to an apparatus for melting and kneading sheet material by rotating a built-in screw. The shape and number of screws are not limited, and may be a single axis, a biaxial axis, or a multiaxial axis of three or more axes. The rotation direction of the screw may be either the same direction or a different direction.

  “Gear pump” refers to a device that measures and transports sheet material by rotating a built-in gear. The number and shape of the gears are not limited.

  “Base” refers to a device that forms and discharges a sheet material into a sheet shape. The shape of the flow path is not limited, and may be a T die, a coat hanger die, an L die, or a fish tail die.

  The “second extruder” refers to an apparatus that transports a sheet material by rotating a built-in screw. The shape and number of screws are not limited, and may be a single axis, a biaxial axis, or a multiaxial axis of three or more axes. The rotation direction of the screw may be either the same direction or a different direction.

  A “pressure measuring device” refers to a device that measures the pressure of a sheet material.

  “Control device” refers to a device that controls the rotational speed of the extruder, gear pump, second gear pump, and second extruder based on data such as pressure and rotational speed.

  With the die of the present invention, it is possible to produce a sheet that achieves both film thickness and high temporal stability.

Schematic of the sheet manufacturing apparatus of this embodiment Schematic of a sheet manufacturing apparatus provided with the 2nd extruder of this embodiment Schematic at the time of molding of the resin extrusion molding device of Patent Document 1 Schematic diagram when starting up the resin extrusion molding device of Patent Document 1 and changing the discharge amount

  The present invention will be described in detail below, but the present invention is not limited to the embodiments including the following examples.

  1 and 2 are views relating to a sheet manufacturing apparatus of the present invention. In addition, about the member which has the same use and function as a prior art, it may have the same code | symbol.

  The sheet manufacturing apparatus of the present invention will be described. FIG. 1 is a schematic view of a sheet manufacturing apparatus according to the present invention. As shown in FIG. 1, the sheet material is melted and extruded by an extruder 1, the sheet material extruded from the extruder 1 is transported by a first gear pump 2, and the sheet transported from the first gear pump 2 is further transported. The material is transported by the second gear pump 3, and the sheet material transported from the second gear pump 3 is formed into a sheet shape by the base 4. The control device 10 controls the extruder 1 and the second gear pump 3 so that their rotational speeds are constant, respectively, and pressure measurement for measuring the pressure of the sheet material provided at the outlet of the extruder 1. The rotational speed of the first gear pump 2 is controlled so that the pressure value of the sheet material in the container 31 is constant. Then, the formed sheet is solidified, and is subjected to a post-treatment such as stretching as it is, to form a film. Thus, (i) by controlling the rotation speed of the extruder 1 to be constant, the state of melting and kneading of the sheet material in the extruder is made constant, the physical properties of the film are kept constant, and in addition, ( ii) Even if the rotational speed of the first gear pump is controlled so that the pressure at the outlet of the extruder 1 is constant, the state of melting and kneading of the sheet material in the extruder is made constant, and the physical properties of the film are made constant. Further, (iii) by controlling the rotational speed of the second gear pump 3 to be constant, the amount of sheet material conveyed from the second gear pump 3 can be kept constant, and the film thickness can be kept constant. That is, it is possible to achieve both the film thickness and the stability over time with high physical properties. In the above description, the mode in which the rotation speed of each of the extruder 1, the first gear pump 2, and the second gear pump is controlled by one control device 10 has been described. Control devices for controlling the rotational speeds of the gear pump 2 and the second gear pump 3 may be provided separately.

  The sheet manufacturing apparatus of the present invention further includes a second extruder 5 between the first gear pump 2 and the second gear pump 3, and the sheet material transported from the first gear pump 2 is second extruded. Extrusion by the machine 5 and transportation to the second gear pump 3 are preferred. FIG. 2 is a schematic view of the sheet manufacturing apparatus of the present invention including the second extruder 5. Since both the first gear pump 2 and the second gear pump 3 are highly meterable, if there is a difference in the transport amount of the sheet material of each gear pump, the pressure of the sheet material that has lost its place of travel may increase and fluctuate greatly. is there. Therefore, by providing the second extruder 5 having a lower meterability than the gear pump between the gear pumps, it is possible to absorb the difference in the transport amount and suppress the fluctuation of the pressure. The pressure at the outlet of the extruder 1, the front of the second extruder, the front of the second gear pump, etc. is measured, and the control device 10 controls the rotational speed of the second extruder 5 based on the result. Also good.

  In the sheet manufacturing method of the present invention, it is preferable that the control device 10 further controls the rotation speed of the second extruder 5 to be constant. Although the influence is lower than that of the first extruder 1, the rotational speed of the second extruder 2 also affects the physical properties of the film. Therefore, by making the rotation speed of the second extruder 5 constant, it is possible to improve the temporal stability of the film properties while suppressing the pressure fluctuation between the gear pumps. In the above description, the control device 10 controls the rotational speed of the second extruder 5. However, of course, a control device that controls the rotational speed of the second extruder 5 may be provided separately. .

  Typical applications of the film produced by the sheet production method of the present invention are general optical, general industrial, adhesive tape, display, backlight reflector, touch panel, window pasting, capacitor, battery separator, solar Although it is a battery, a mold release, and a ribbon, it is not restricted to these.

[Example 1]
The result of actually manufacturing and evaluating a film using the sheet manufacturing apparatus shown in FIG. 1 will be described. A specific sheet manufacturing method in the present embodiment is as follows.
(1) Sheet material: Polyethylene terephthalate (PET) resin (thermoplastic resin F20S manufactured by Toray Industries, Inc.)
(2) Preparation: Sheet material is supplied to the extruder after drying. The extrusion rate was set to 100 kg / h, and the temperature from the extruder to the die was set to 280 ° C.
(3) Rotational speed control: The rotational speed of the extruder is controlled to be constant, the rotational speed of the first gear pump is controlled so that the pressure at the outlet of the extruder is constant, and the rotational speed of the second gear pump is controlled to be constant. did.
(4) Base: slit width 500 mm, slit gap 2 mm.
(5) Discharge: After extruding from the die into a sheet shape, the sheet was rapidly cooled and solidified with cold water to form a sheet thickness of 1 mm.
(6) Evaluation of physical properties: In a cooled and solidified sheet, the Young's modulus is measured in accordance with “ASTM-D-882” by measuring the thickness of the central portion in the width direction of the sheet every 0.5 m in accordance with “ASTM-D-882”. The value obtained by dividing the difference between the value and the minimum value by the average value was defined as physical property unevenness.
(7) Thickness evaluation: In a cooled and solidified sheet, the thickness of the central part in the width direction of the sheet is measured 10 m in the flow direction with a thickness meter “TOF-4R” (manufactured by Yamabun Electric Co., Ltd.). A value obtained by dividing the difference by the average value was defined as thickness unevenness.

  As a result, it was possible to produce a sheet having both physical property non-uniformity of 3.2% and thickness non-uniformity of 2.6%, which is compatible with thickness and stability over time. Further, the pressure before the second gear pump fluctuated by a maximum of 12%.

[Example 2]
A film was produced in the same manner as in Example 1 except that a second extruder was provided as shown in FIG. The rotational speed of the second extruder was controlled so that the pressure before the second gear pump was constant. As a result, it was possible to produce a sheet having both physical property unevenness of 2.9% and thickness unevenness of 2.5%, with both thickness and high physical property stability over time. Furthermore, the pressure fluctuation before the second gear pump could be suppressed to a maximum of 6%.

[Example 3]
A film was produced in the same manner as in Example 2 except that the rotation speed of the second extruder was controlled to be constant. As a result, with the pressure fluctuation before the second gear pump suppressed to a maximum of 5%, it is possible to produce a sheet that has both physical properties unevenness 2.1%, thickness unevenness 1.7%, and thickness and high physical property stability over time. We were able to.

[Comparative Example 1]
A film was produced in the same manner as in Example 1 except that the rotation speed of the first gear pump was controlled to be constant. As a result, the pressure at the outlet of the extruder fluctuated, and vent-up occurred and a sheet to be evaluated could not be manufactured.

[Comparative Example 2]
A film was produced in the same manner as in Example 1 except that the rotation speed of the second gear pump was controlled so that the pressure before the second gear pump was a constant pressure. As a result, although the physical property unevenness was as small as 4.2%, the second gear pump rotation speed fluctuated, so the thickness unevenness increased to 15.7%, producing a sheet with both thickness and high physical property stability over time. I couldn't.

[Comparative Example 3]
A film was produced in the same manner as in Example 1 except that the rotational speeds of the extruder and the first gear pump were controlled so that the pressure before the second gear pump was a constant pressure. As a result, although the thickness unevenness was 3.7%, it was small, but because the rotational speed of the extruder fluctuated, the physical property unevenness increased to 12.3%, and a sheet having both thickness and high physical property stability over time was manufactured. I couldn't.

  According to the present invention, by controlling the rotational speeds of the extruder and the second gear pump to be constant, it is possible to achieve both the thickness and the stability over time with high physical properties, and to improve the quality and productivity.

1: Extruder 2: First gear pump 3: Second gear pump 4: Base 5: Second extruder 6: First filtration device 7: Second filtration device 10: Control device 11 for controlling the rotational speed , 12, 13, 14: Control means 31, 32 for controlling the rotational speed based on the pressure: Pressure measuring device 101 for measuring the pressure of the sheet material 101: Sheet manufacturing apparatus 102 of the present invention: Resin extrusion molding apparatus of Patent Document 1

Claims (6)

The sheet material is melted and extruded by an extruder, the sheet material extruded from the extruder is transported by a first gear pump, and the sheet material transported from the first gear pump is transported by a second gear pump, A sheet manufacturing method in which a sheet material transported from the gear pump of 2 is formed into a sheet shape with a die,
The extruder and the second gear pump are controlled to operate at a constant rotational speed, respectively.
A method for manufacturing a sheet, wherein the first gear pump is operated by controlling a rotation speed thereof so that a pressure value of a sheet material at an outlet of the extruder is constant.   A second extruder is further provided between the first gear pump and the second gear pump, the sheet material transported from the first gear pump is extruded by the second extruder, and the second extruder The manufacturing method of the sheet | seat of Claim 1 transported to a gear pump.   The sheet manufacturing method according to claim 2, wherein the second extruder is operated while controlling the rotation speed to be constant. An extruder for melting the sheet material;
A first gear pump provided downstream of the extruder for transporting sheet material;
A second gear pump for transporting sheet material provided downstream of the first gear pump;
A base provided on the downstream side of the second gear pump for forming a sheet material into a sheet shape;
A pressure measuring device provided at the outlet of the extruder for measuring the pressure of the sheet material;
A control device for controlling the respective rotational speeds of the extruder, the first gear pump, and the second gear pump so that the rotational speeds of the extruder and the second gear pump are constant. And a control device for controlling the rotation speed of the first gear pump so that the pressure value of the sheet material measured by the pressure measuring device is constant.   The sheet manufacturing apparatus according to claim 4, further comprising a second extruder between the first gear pump and the second gear pump.   The sheet manufacturing apparatus according to claim 5, further comprising a control device that controls the rotation speed of the second extruder to be constant.

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