Apparatus for manufacturing microporous polyolefin resin sheet and method for manufacturing microporous polyolefin resin sheet
Patent Information
- Application Number
- JP2024559606
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Priority Date
- 2023-11-06
- Filing Date
- 2024-09-19
- Publication Date
- 2025-05-15
AI Technical Summary
Existing microporous polyolefin resin sheet manufacturing devices suffer from liquid defects such as poor appearance and tears due to coagulated liquids adhering to the inner walls of the pressure reduction chamber and falling onto the casting device, despite the use of liquid receivers to capture these liquids.
The manufacturing device incorporates a pressure reduction chamber with an inclined inner wall surface that directs coagulated liquids to a suction port located between the end of the chamber and the casting device, allowing the liquids to be sucked out and prevented from falling onto the casting device.
This configuration effectively suppresses the drop of coagulated liquids onto the casting device, resulting in stable and high-quality microporous polyolefin resin sheets with reduced liquid defects.
Abstract
Description
Apparatus for producing microporous polyolefin resin sheet and method for producing microporous polyolefin resin sheet
[0001] The present invention relates to an apparatus for producing a microporous polyolefin resin sheet and a method for producing a microporous polyolefin resin sheet.
[0002] First, a typical microporous polyolefin resin sheet manufacturing apparatus will be described. FIG. 5 is a perspective view of a typical microporous polyolefin resin sheet manufacturing apparatus. As shown in FIG. 5, the typical manufacturing apparatus includes a die 1 having a discharge port 5 for discharging a sheet material 3 containing a polyolefin resin and a diluent; a casting device 2 that cools and solidifies the sheet material 3 discharged from the discharge port 5 while transporting it; and a decompression chamber 4 located upstream of the discharge port 5 in the sheet transport direction Q, covering a space 7 (hereinafter referred to as a decompression space) between the sheet material 3 and the casting device 2, and using an intake / exhaust nozzle 6 to suction air to reduce the pressure of the decompression space 7. The sheet material 3 discharged from the discharge port 5 of the die 1 toward the casting device 2 is brought into close contact with the casting device 2 by reducing the pressure of the decompression space 7, and is cooled and solidified while transported by the casting device 2. Here, the installation position of the intake / exhaust nozzle 6 is not limited, and is not limited to both ends of the decompression chamber 4 in the sheet width direction Y as shown in FIG. 5.
[0003] Here, because the sheet discharged from the die is at a high temperature, gases derived from the low-molecular-weight components, diluents, and additives inside the sheet are generated, and these gases adhere to the walls of the decompression chamber, condensing and liquefying. Figure 6 is a cross-sectional view perpendicular to the sheet width direction Y of a typical microporous polyolefin resin sheet manufacturing device. As shown in Figure 6, the condensate 10 that adheres to the inner wall surface 9 of the decompression chamber 4, condenses, and liquefies, gradually increases in size, and if it falls into the casting device 2 due to its own weight or the air current in the decompression space, it will cause defects in the sheet, such as poor appearance and tearing.
[0004] Patent Document 1 discloses a resin sheet manufacturing apparatus as a technology for suppressing liquid defects. Patent Document 1 discloses a resin sheet manufacturing apparatus equipped with an inclined inner wall surface and a liquid receiver for the purpose of capturing the condensate before it falls. FIG. 7 is a cross-sectional view perpendicular to the sheet width direction Y of the resin sheet manufacturing apparatus described in Patent Document 1. As shown in FIG. 7, in the manufacturing apparatus of Patent Document 1, the condensate 10 adhering to the inner wall surface 9 flows along the inclination before it becomes large, is captured in the liquid receiver 11, and is discharged, thereby suppressing it from falling into the casting device 2.
[0005] International Publication No. 2016 / 125526
[0006] However, in the resin sheet manufacturing apparatus of Patent Document 1, a certain amount of agglomerate liquid accumulates in the liquid receiver, and is scattered by the air flow in the reduced pressure space and falls into the casting device, so liquid defects cannot be completely eliminated and no method for suppressing this has been proposed.
[0007] Therefore, the present invention provides an apparatus and method for producing a microporous polyolefin resin sheet that can stably produce high-quality sheets by preventing the condensate from falling into a casting device without providing a liquid receiver.
[0008] [1] The present invention, which solves the above-mentioned problems, provides a manufacturing apparatus for a microporous polyolefin resin sheet, comprising: a die having a discharge port for discharging a sheet material containing a polyolefin resin and a diluent; a casting device for cooling and solidifying the sheet material discharged from the discharge port while transporting it; and a decompression chamber arranged upstream of the discharge port in the sheet transport direction, covering the space between the sheet material and the casting device, and sucking air to create a decompressed space, wherein, when viewed in cross section from the sheet width direction, the inner wall surface of the decompression chamber is inclined downward in the vertical direction from one end close to the discharge port to the other end, and the other end is located at a distance from the casting device; and a suction port is provided between the other end of the decompression chamber and the casting device for sucking air from the inside to the outside of the decompression chamber, and the other end forms the vertical upper edge of the suction port.
[0009] The apparatus for producing a microporous polyolefin resin sheet of the present invention is preferably in any one of the following embodiments [2] to [4]. [2] The apparatus for producing a microporous polyolefin resin sheet of [1] above, in a cross-sectional view from the sheet width direction, the horizontal distance A [mm] from the other end to the edge vertically below the suction port and the gap B [mm] between the suction ports satisfy A / B≦5. [3] The apparatus for producing a microporous polyolefin resin sheet of [1] or [2] above, in a cross-sectional view from the sheet width direction, the inner wall surface is bent near the other end, and the inner wall surface forms an acute angle with the horizontal direction, the angle on the other end side from the bent point being 30 degrees or more larger than the angle on the one end side. [4] The apparatus for producing a microporous polyolefin resin sheet of any one of [1] to [3] above, in which the length of the suction port in the sheet width direction is equal to or greater than the length of the inner wall surface in the sheet width direction.
[0010] [5] The present invention, which solves the above-mentioned problems, is a method for producing a microporous polyolefin resin sheet, using the microporous polyolefin resin sheet production apparatus of any one of [1] to [4] above, discharging a sheet material containing a polyolefin resin and a diluent from the discharge port toward the casting device, suctioning the air in the decompression chamber to create a decompressed space, and bringing the sheet material into close contact with the casting device, wherein the condensate that has adhered to the inner wall surface of the decompression chamber and travels along this inner wall surface to reach the other end is sucked out of the decompression chamber through the suction port, while the sheet material is transported by the casting device and cooled to solidify.
[0011] [Terminology] The meaning of each term used in the present invention will be explained.
[0012] "Sheet material" refers to the material that constitutes the sheet. Examples of sheet materials include polyolefin solution resins prepared by mixing a polyolefin resin, such as polyethylene, polypropylene, polystyrene, or polymethylpentene, with a diluent and then heating and melting the mixture. The diluent is not particularly limited as long as it can be mixed or dissolved in the polyolefin resin. Materials that are miscible with the polyolefin in the melt-kneaded state but solid at room temperature may also be used. Examples of solid diluents include stearyl alcohol, ceryl alcohol, and paraffin wax. To prevent unevenness during stretching and to allow for subsequent application, the diluent is preferably liquid at room temperature. Examples of liquid diluents include aliphatic, cycloaliphatic, or aromatic hydrocarbons such as nonane, decane, decalin, paraxylene, undecane, dodecane, and liquid paraffin, as well as mineral oil fractions with corresponding boiling points, and phthalate esters that are liquid at room temperature, such as dibutyl phthalate and dioctyl phthalate. Liquid paraffin is even more preferable for obtaining a stable gel-like sheet. The viscosity of the liquid diluent is preferably 20 to 200 cSt at 40°C. The blending ratio of the polyolefin resin and the diluent is preferably 10 to 50% by mass of the polyolefin resin and 50 to 90% by mass of the diluent, with the total of the polyolefin resin and the diluent being 100% by mass, from the viewpoint of improving the moldability of the extrudate. The uniform melt-kneading process for the sheet material is not particularly limited, but examples include a calender, various mixers, and an extruder equipped with a screw.
[0013] A "die" refers to a device that discharges sheet material and molds it into a sheet. A "discharge port" refers to the part of the die that discharges the sheet material. A "casting device" refers to a device that conveys the sheet material discharged from the discharge port downstream while cooling and solidifying it by tightly adhering it to the material. There are no particular limitations on the form, but examples include rolls and belts.
[0014] The "sheet width direction" refers to the direction that coincides with the width direction of the sheet material when it is formed into a sheet by the die, and is the direction indicated by the symbol Y in each drawing. The "sheet transport direction" refers to the direction in which the casting device transports the sheet immediately below the die, and is the direction indicated by the symbol Q in each drawing. The transport destination is the downstream side, and the opposite is the upstream side.
[0015] The "reduced pressure space" refers to a space formed between the sheet material and the casting device, which is covered with a reduced pressure chamber and is kept at a negative pressure. The "reduced pressure chamber" refers to a device that covers the space between the sheet material and the casting device and reduces the pressure to bring the sheet material into close contact with the casting device. Generally, the pressure inside the reduced pressure chamber is -1500 Pa or more and -50 Pa or less relative to atmospheric pressure. The pressure inside the reduced pressure chamber may also be controlled according to the film-forming conditions.
[0016] The "inner wall surface" refers to the wall surface of the vacuum chamber facing the vacuum space when viewed in a cross-sectional view from the sheet width direction. The "one end" refers to the end of the inner wall surface closest to the discharge port when viewed in a cross-sectional view from the sheet width direction. The "other end" refers to the end of the inner wall surface farthest from the discharge port when viewed in a cross-sectional view from the sheet width direction. The "near the other end" refers to a range within 10 mm from the other end. The "suction port" refers to an opening located between the other end and the casting device, for sucking air from the inside of the vacuum chamber to the outside. The shape is not particularly limited, but examples include square, rectangular, trapezoidal, circular, and elliptical openings, and multiple openings may be arranged in the sheet width direction. The wall surface may be surface-treated, such as nickel-plated, chrome-plated, or zinc-plated. The power source for suction is not particularly limited, but examples include a blower and a vacuum pump.
[0017] According to the polyolefin resin sheet manufacturing apparatus and manufacturing method of the present invention, high-quality sheets can be stably manufactured by preventing the condensate adhering to the inner wall surface of the decompression chamber from falling onto the casting device.
[0018] FIG. 1 is a cross-sectional view perpendicular to the sheet width direction of one embodiment of the apparatus for producing a microporous polyolefin resin sheet of the present invention. FIG. 2 is a partially enlarged view of the vicinity of the suction port in FIG. 1. FIG. 3 is a cross-sectional view perpendicular to the sheet width direction near the suction port of the apparatus for producing a microporous polyolefin resin sheet of the present invention, and is a diagram of an embodiment of the apparatus for producing a microporous polyolefin resin sheet in which A / B = 5. FIG. 4 is a cross-sectional view perpendicular to the sheet width direction of the apparatus for producing a microporous polyolefin resin sheet of the present invention, and is a diagram of an embodiment of the apparatus for producing a microporous polyolefin resin sheet in which the inner wall surface is bent near the other end so that the angle it forms with the horizontal direction is 45 degrees larger. FIG. 5 is a perspective view of a general apparatus for producing a microporous polyolefin resin sheet. FIG. 6 is a cross-sectional view perpendicular to the sheet width direction of a general apparatus for producing a microporous polyolefin resin sheet. FIG. 7 is a cross-sectional view perpendicular to the sheet width direction of the apparatus for producing a resin sheet described in Patent Document 1.
[0019] The present invention will be described in detail below, but is not limited to the following examples. Figures 1 to 4 are diagrams showing an apparatus for producing a microporous polyolefin resin sheet according to the present invention. Note that components having the same uses and functions as those in the prior art may be designated by the same reference numerals.
[0020] The microporous polyolefin resin sheet manufacturing apparatus of the present invention will be described. FIG. 1 is a cross-sectional view perpendicular to the sheet width direction Y of one embodiment of the microporous polyolefin resin sheet manufacturing apparatus of the present invention. FIG. 2 is a partial enlarged view of the vicinity of the suction port in FIG. 1. The manufacturing apparatus includes a die 1 having a discharge port 5 for discharging a sheet material 3 containing a polyolefin resin and a diluent, a casting device 2 that cools and solidifies the sheet material 3 discharged from the discharge port 5 while transporting it, and a decompression chamber 4 located upstream of the discharge port 5 in the sheet transport direction Q, covering the space (decompression space) between the sheet material 3 and the casting device 2, and sucking air to decompress the decompression space. In the manufacturing apparatus, the sheet material 3 discharged from the discharge port 5 of the die 1 toward the casting device 2 is brought into close contact with the casting device 2 by decompressing the decompression space, and is cooled and solidified while transported by the casting device 2.
[0021] 1 , in the apparatus for producing a microporous polyolefin resin sheet of the present invention, in a cross-sectional view from the sheet width direction Y, the inner wall surface 9 of the decompression chamber 4 is inclined downward in the vertical direction (Z direction) (toward the casting device 2) from one end 12, which is the end closest to the discharge outlet 5, to the other end 13, which is the end farthest from the discharge outlet 5, and the other end 13 is located at a distance from the casting device 2. A suction port 14 for sucking air from the inside of the decompression chamber 4 to the outside is formed between the other end 13 of the decompression chamber 4 and the casting device 2, and the other end 13 forms the upper edge of the suction port 14 in the vertical direction. Because the inner wall surface 9 is inclined downward in the vertical direction from the one end 12 to the other end 13, the flocculating liquid 10 adhering to the inner wall surface 9 flows along the inclination to reach the other end 13. As shown in FIG. 2, the condensate 10 that has reached the other end 13 becomes large and is sucked into the suction port 14 and discharged outside the decompression chamber 4 before it falls due to its own weight or air current, so that the condensate 10 does not fall into the casting device 2, thereby suppressing liquid defects.
[0022] In the microporous polyolefin resin sheet production apparatus of the present invention, when viewed in cross section in the sheet width direction (Y direction), the horizontal (X direction) distance A [mm] (hereinafter referred to as landing distance A) from the other end 13 to the lower edge of the suction port in the vertical direction (Z direction) and the gap B [mm] between the suction ports preferably satisfy A / B≦5. Here, the value of distance A is positive when the lower edge of the suction port in the vertical direction is downstream of the other end in the sheet conveying direction, and negative when it is upstream in the sheet conveying direction. Figure 3 is a cross-sectional view perpendicular to the sheet width direction near the suction port of the microporous polyolefin resin sheet production apparatus of the present invention, showing a production apparatus in which A / B=5. As shown in Figure 3, when A / B≦5, the airflow 8 generated by suction through the suction port 14 also flows near the lower vertical edge 15. Therefore, even if the condensate 10 adheres near the edge 15, it can be sucked in, thereby suppressing liquid defects. More preferably, A / B≦3. The lower limit of A / B is preferably −1 (A / B≧−1). The dimension B is determined by the film-forming conditions, but if the suction port is small, clogging with droplets or the like will cause unstable suction, so B is preferably 0.5 mm or more, and more preferably 1 mm or more.
[0023] In the apparatus for producing a microporous polyolefin resin sheet of the present invention, in a cross-sectional view from the sheet width direction (Y direction), the inner wall surface 9 is bent near the other end 13, and the acute angle formed between the inner wall surface 9 and the horizontal direction, the angle θ1 on the side of the bent portion 16 (hereinafter referred to as the bent portion 16) toward the other end 13, is preferably 30 degrees or more larger than the angle θ2 on the side of the one end 12. Figure 4 is a cross-sectional view perpendicular to the sheet width direction Y of the apparatus for producing a microporous polyolefin resin sheet of the present invention, and is a diagram of a production apparatus in which the inner wall surface is bent so that the angle with the horizontal direction is 45 degrees larger near the other end 13. As shown in Figure 4, because the inner wall surface 9 is bent near the other end 13, the condensate 10 flowing down along the inner wall surface 9 toward the other end 13 is blocked by the inner wall surface 9 at the bent portion 16, and the flow rate of the condensate 10 is temporarily slowed. Since the flow of the condensate 10 slows down at the bent portion 16 before it reaches the other end 13, it is more likely to be sucked into the suction port 14. It is more preferable that the inner wall surface be bent so that the angle with the horizontal direction near the other end is 45 degrees or larger. In the embodiment shown in FIG. 4 , the other end 13 is located upstream of the bent portion 16 in the sheet conveying direction, but the inner wall surface 9 may also be bent so that the other end 13 is located downstream of the bent portion 16 in the sheet conveying direction.
[0024] In the microporous polyolefin resin sheet manufacturing apparatus of the present invention, the length of the suction port in the sheet width direction (Y direction) is preferably equal to or greater than the length of the inner wall surface in the sheet width direction Y. By having the suction range of the suction port equal to or greater than the inner wall surface, the flocculating liquid flowing along the inner wall surface can be sucked in without letting it escape. Here, the "length of the suction port in the sheet width direction" refers to the length of each suction port in the sheet width direction (Y direction) in an embodiment in which multiple suction ports are arranged in the sheet width direction (Y direction).
[0025] In the method for producing a microporous polyolefin resin sheet of the present invention, the condensate that adheres to the inner wall surface of a decompression chamber and travels down the inner wall surface to the other end is sucked out of the decompression chamber through a suction port while the sheet material is transported by a casting device and cooled and solidified. The flow of the condensate is explained with reference to Figure 1. The condensate 10 that adheres to the inner wall surface 9 of the decompression chamber reaches the other end 13 along a slope. The condensate 10 that arrives at the other end 13 is sucked out of the decompression chamber through a suction port 14 and removed, thereby suppressing liquid defects.
[0026] In the apparatus for producing a microporous polyolefin resin sheet according to the present embodiment described above, when viewed in cross section in the sheet width direction, the inner wall surface 9 of the decompression chamber 4 is inclined downward in the vertical direction from one end 12 close to the discharge port 5 toward the other end 13, the other end 13 being spaced apart from the casting device 2, and a suction port 14 for sucking air from the inside of the decompression chamber 4 to the outside is provided between the other end of the decompression chamber 4 and the casting device 2, with the other end 13 being on the vertical upper edge of the suction port 14. According to the present embodiment, the above-described configuration makes it possible to prevent the coagulation liquid from falling into the casting device without providing a liquid receiver, thereby enabling the stable production of high-quality sheets.
[0027] Hereinafter, examples of polyolefin resin sheet production using the polyolefin resin sheet production apparatus of the present invention will be described.
[0028] [Example 1] A polyolefin resin sheet was actually produced using a polyolefin resin sheet production apparatus, and the results of evaluating liquid defects will be described. Specific sheet production conditions and a method for evaluating liquid defects in this embodiment are as follows.
[0029] (1) Sheet materials: High-density polyethylene (HDPE): viscosity 1000 Pa s. Here, the viscosity was measured at a shear rate of 100 / s and a temperature of 200°C according to the method of JIS K7117-2. Liquid paraffin (LP): kinematic viscosity 50 cSt (at 40°C). The mixing ratio of HDPE to LP was HDPE:LP = 30:70 by mass.
[0030] (2) Extrusion Using an extruder, the sheet material was extruded at a flow rate of 250 kg / h, passed through a gear pump and a filter, and then fed to a die. The temperature of the extruder up to the die was 220°C.
[0031] (3) Die: The sheet material was discharged from a 500 mm wide discharge port and formed into a sheet. The amount of LP volatilized from the discharged sheet was measured and found to be about 100 g / h.
[0032] (4) Casting Apparatus The sheet was brought into close contact with a sheet forming roll at a temperature of 35°C, and then cooled and solidified.
[0033] (5) Decompression Chamber The decompression chamber is installed upstream of the die's discharge port in the sheet conveying direction (Q direction) and is shaped to cover the space between the sheet material discharged from the discharge port and the casting device. When viewed in cross section in the sheet width direction (Y direction), the inner wall surface of the decompression chamber is inclined at a constant angle of 30 degrees (=θ2) from the horizontal, tilting downward in the vertical direction (Z direction) from one end closest to the discharge port to the other end, with the other end located 3 mm away from the casting device. A suction port is located between the other end of the decompression chamber and the casting device, and the other end forms the upper vertical edge of the suction port. The inner wall surface has a sheet width dimension of 500 mm. Five suction ports are arranged in the sheet width direction, with a landing distance A of 6 mm, a gap B of 1 mm (A / B = 6), and a sheet width dimension of 50 mm. Exhaust nozzles are also arranged opposite each other on the wall surfaces at both ends of the decompression chamber. In this state, the inside of the decompression chamber was evacuated from atmospheric pressure to −600 Pa by a blower connected to the exhaust nozzle and the suction port.
[0034] (6) Defect Detector Using a MaxEye Impact (manufactured by Hutec Co., Ltd.) as an inspection device, the number of liquid defects on the sheet (length 100 m) sampled under the above conditions was counted.
[0035] Example 2 Sheets were collected in the same manner as in Example 1, except that the landing distance A of the suction port was changed to 5 mm (A / B=5).
[0036] Example 3 Sheets were collected in the same manner as in Example 1, except that the landing distance A of the suction port was changed to 3 mm (A / B=3).
[0037] Example 4 A sheet was collected in the same manner as in Example 1, except that the landing distance A of the suction port was changed to 0 mm (A / B=0).
[0038] Example 5 A sheet was collected in the same manner as in Example 1, except that the landing distance A of the suction port was changed to −0.5 mm (A / B=−0.5).
[0039] Example 6 A sheet was collected in the same manner as in Example 1, except that the gap B of the suction port was changed to 2 mm (A / B=3).
[0040] [Example 7] A sheet was collected in the same manner as in Example 1, except that, when viewed in cross section from the sheet width direction Y, the inner wall surface of the decompression chamber was bent so that the angle (θ1) with the horizontal direction was 75 degrees, 45 degrees larger than θ2, at a position downstream of the other end 13 in the sheet conveying direction and 5 mm from the other end 13 (see Figure 4).
[0041] Example 8 A sheet was collected in the same manner as in Example 1, except that one suction port having a dimension of 500 mm in the sheet width direction was provided.
[0042] Comparative Example 1 A sheet was collected in the same manner as in Example 1, except that the inner wall surface of the decompression chamber was horizontal in cross section in the sheet width direction and no suction port was provided.
[0043] Comparative Example 2 A sheet was collected in the same manner as in Example 1, except that the configuration shown in FIG. 7 was used, in which a liquid receiver connected to the inner wall surface of the decompression chamber was provided and no suction port was provided.
[0044] [Evaluation Results] The effect of each Example was evaluated based on the degree to which liquid defects were reduced compared to Comparative Examples 1 and 2.
[0045] Comparative Example 1 had 66 liquid defects. Comparative Example 2, in which the inner wall surface of the decompression chamber was inclined and a liquid receiver was provided, had 34 liquid defects, which was a reduction in the number of liquid defects compared to Comparative Example 1.
[0046] On the other hand, in Example 1, in which the inner wall surface of the decompression chamber was inclined and a suction port was provided near the other end, the number of liquid defects was seven, which was a decrease in the number of liquid defects compared to Comparative Example 2.
[0047] Example 2, which satisfied the condition A / B≦5, had four liquid defects, Example 3 had one liquid defect, Example 4 had zero liquid defects, Example 5 had one liquid defect, and Example 6 had zero liquid defects, and all of these examples had fewer liquid defects than Example 1.
[0048] In Example 7, which had a bent portion near the other end, there were four liquid defects, which was a reduction in liquid defects compared to Example 1.
[0049] In Example 8, in which one suction port having a dimension of 500 mm in the sheet width direction Y is arranged, the number of liquid defects was three, which is a reduction in the number of liquid defects compared to Example 1.
[0050] The present invention is not limited to a manufacturing apparatus and manufacturing method for a microporous polyolefin resin sheet, but can also be applied to a manufacturing apparatus and manufacturing method for a solution resin sheet, die coating, etc., but the scope of application is not limited to these.
[0051] REFERENCE SIGNS LIST 1 die 2 casting device 3 sheet material 4 vacuum chamber 5 discharge port 6 exhaust nozzle 7 vacuum space 8 air flow 9 inner wall surface 10 condensate 11 liquid receiver 12 one end 13 other end 14 suction port 15 vertical lower edge of suction port 16 bent portion A landing distance B gap of suction port Q sheet conveying direction X horizontal direction Y sheet width direction Z vertical direction
Claims
1. An apparatus for producing microporous polyolefin resin sheets, comprising: a die having an outlet for discharging a sheet material containing a polyolefin resin and a diluent; a casting device for cooling and solidifying the sheet material discharged from the outlet while transporting it; and a decompression chamber arranged upstream of the outlet in the sheet transport direction, covering the space between the sheet material and the casting device, and drawing in air to create a decompressed space, wherein, when viewed in cross-section from the sheet width direction, the inner wall surface of the decompression chamber is inclined vertically downward from one end close to the outlet to the other end, the other end being located at a distance from the casting device, and a suction port is provided between the other end of the decompression chamber and the casting device for drawing air from the inside of the decompression chamber to the outside, and the other end forms the vertical upper edge of the suction port.
2. A manufacturing apparatus for a microporous polyolefin resin sheet as claimed in claim 1, wherein, in a cross-sectional view from the sheet width direction, the horizontal distance A [mm] from the other end to the vertically lower edge of the suction port and the gap B [mm] of the suction port satisfy A / B≦5.
3. A manufacturing apparatus for a microporous polyolefin resin sheet as claimed in claim 1, wherein, when viewed in cross section from the sheet width direction, the inner wall surface is bent near the other end, and the angle formed by the inner wall surface and the horizontal direction is an acute angle which is 30 degrees or more greater on the other end side than the bent point than the angle on the one end side.
4. The apparatus for producing a microporous polyolefin resin sheet according to claim 1, wherein the length of the suction port in the sheet width direction is equal to or greater than the length of the inner wall surface in the sheet width direction.
5. A method for producing a microporous polyolefin resin sheet, comprising: using the apparatus for producing a microporous polyolefin resin sheet according to any one of claims 1 to 4; discharging a sheet material containing a polyolefin resin and a diluent from the discharge port toward the casting device; sucking air from within the decompression chamber to create a decompressed space; bringing the sheet material into close contact with the casting device; sucking the condensate that has adhered to the inner wall surface of the decompression chamber and traveled along the inner wall surface to the other end out of the decompression chamber from the suction port; and cooling and solidifying the sheet material while transporting it with the casting device.