Resin sheet manufacturing apparatus and resin sheet manufacturing method

Abstract

To provide a resin sheet manufacturing apparatus and manufacturing method that can stably manufacture high-quality sheets.SOLUTION: A resin sheet manufacturing apparatus of the present invention includes: a mouthpiece that extrudes a resin sheet material as a resin sheet; a casting device that cools and solidifies the resin sheet extruded from the mouthpiece while transporting the same; and an air knife that blows air toward the resin sheet to adhere the same to the casting device. The air knife has, on a surface facing the casting device, a first blowing outlet, an exhaust outlet, and a second blowing outlet, in order from a downstream side in a transport direction, and when observed from a width direction, an air blowing direction of the second blowing outlet is inclined downstream in the transport direction relative to the direction perpendicular to the surface of the casting device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a resin sheet manufacturing apparatus and a resin sheet manufacturing method. [Background technology]

[0002] First, a typical resin sheet manufacturing apparatus will be described. Fig. 7 is a side view of a typical resin sheet manufacturing apparatus. As shown in Fig. 7, the typical manufacturing apparatus includes a die 1 that discharges a resin sheet material as a resin sheet 3, and a casting device 2 that cools and solidifies the resin sheet 3 discharged from the die 1 while transporting it. The resin sheet manufacturing apparatus in Fig. 7 also includes an air knife 4 that blows air toward the resin sheet 3 to adhere the resin sheet 3 to the casting device 2.

[0003] Here, we will explain the flow of air blown out from the air knife. Figure 4 is an enlarged view of the area around the air knife of a typical resin sheet manufacturing device, and is a cross-sectional view perpendicular to the width direction of the resin sheet (hereinafter abbreviated as "width direction"). As shown in Figure 4, the air knife 4 blows out air 10 from a first outlet 6 to bring the resin sheet 3 into close contact with the casting device 2. After colliding with the resin sheet 3, the air 10 is divided into air 10a flowing upstream in the conveyance direction of the resin sheet 3 (hereinafter referred to as the conveyance direction) and air 10b flowing downstream. If the volume of this air 10a is large, it will vibrate the resin sheet 3 from the time it is discharged from the nozzle until it comes into close contact with the casting device 2, causing instability in film production such as uneven thickness.

[0004] One method for suppressing vibration of the resin sheet 3 is to reduce the volume of the air 10a by tilting the direction in which the first air outlet 6 blows the air 10 (hereinafter referred to as the air blowing direction) downstream in the conveyance direction rather than perpendicular to the surface of the casting device 2 when viewed from the width direction. However, this reduces the force with which the air 10 strikes the resin sheet 3, i.e., the adhesion strength, so in order to achieve high adhesion, it is necessary to increase the volume of the air 10. This leads to increased costs, such as requiring a larger blower. Furthermore, increasing the volume of the air 10 also increases the volume of the air 10a, ultimately leading to vibration of the resin sheet 3. As such, it is difficult to simultaneously suppress vibration of the resin sheet and achieve high adhesion strength.

[0005] As a technique for suppressing vibration of the resin sheet, Patent Document 1 discloses a film / sheet forming device equipped with an air passage for the purpose of reducing air flowing upstream in the conveyance direction. Figure 5 is an enlarged view of the air knife and its vicinity in the film / sheet forming device of Patent Document 1, and is a cross-sectional view perpendicular to the width direction. As shown in Figure 5, in the device of Patent Document 1, a portion of the air flow 10a flowing upstream in the conveyance direction flows into the air passage 7, thereby suppressing vibration of the resin sheet 3.

[0006] Furthermore, although not intended to suppress vibration of the resin sheet, Patent Document 2 discloses a resin film manufacturing apparatus equipped with a sub-nozzle for the purpose of reducing the accumulation of low-molecular-weight substances. Figure 6 is an enlarged view of the air knife and its vicinity in the resin film manufacturing apparatus of Patent Document 2, and is a cross-sectional view perpendicular to the width direction. As shown in Figure 6, the apparatus of Patent Document 2 suppresses the accumulation of low-molecular-weight substances at the tip of the slit nozzle 6 by blowing air from sub-nozzles 8a and 8b attached to the slit nozzle 6. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Publication No. 61-121923 [Patent Document 2] Publication No. 2012-6271 Summary of the Invention [Problem to be solved by the invention]

[0008] However, in the film / sheet forming device of Patent Document 1, only a portion of the air 10a flowing upstream in the conveyance direction is reduced. Therefore, when a large amount of air 10 is blown out from the air outlet to achieve high adhesion, a large portion of the air 10a does not flow into the air passage 7, making it impossible to suppress vibration of the resin sheet. Furthermore, the resin film manufacturing device of Patent Document 2 does not propose a method for suppressing vibration of the air flowing upstream in the conveyance direction or the resin sheet.

[0009] Therefore, the present invention provides a resin sheet manufacturing apparatus and manufacturing method that can stably manufacture resin sheets by using an air knife to increase the adhesion of the resin sheet to the casting device while suppressing the vibration of the resin sheet. [Means for solving the problem]

[0010] [1] The resin sheet manufacturing apparatus of the present invention, which solves the above problem, comprises a die that discharges a resin sheet material as a resin sheet, a casting device that cools and solidifies the resin sheet discharged from the die while transporting it, and an air knife that blows air toward the resin sheet to make the resin sheet adhere to the casting device, the air knife has, on a surface facing the casting device, a first outlet, an exhaust outlet, and a second outlet, in this order from the downstream side in the conveyance direction; When observed from the width direction, the air blowing direction of the second blowing outlet is inclined downstream in the conveyance direction from the direction perpendicular to the surface of the casting device.

[0011] The resin sheet manufacturing apparatus of the present invention is preferably in the following embodiment [2] or [3]. [2] The resin sheet manufacturing device of [1] above, wherein, when observed from the width direction, the air blowing direction of the first blowing outlet is closer to a direction perpendicular to the surface of the casting device than the air blowing direction of the second blowing outlet. [3] The resin sheet manufacturing device of [1] or [2] above, wherein the shortest distance between the edge of the opening of the second air outlet and the casting device is shorter than the shortest distance between the edge of the opening of the first air outlet and the casting device.

[0012] [4] A method for producing a resin sheet of the present invention that solves the above-mentioned problems is a method for producing a resin sheet, which uses the resin sheet production apparatus of the present invention, discharges a resin sheet material from the die toward the casting device as a resin sheet, blows air from the first blowing outlet toward the resin sheet to make the resin sheet adhere to the casting device, and cools and solidifies the resin sheet while transporting it in the casting device, air is blown out from the second air outlet so as to collide with air flowing upstream in the conveying direction, out of the air blown out from the first air outlet; The air blown out from the first blowout port and flowing toward the upstream side in the transport direction, and the air blown out from the second blowout port are sucked in through the exhaust port.

[0013] [Terminology] The meaning of each term in the present invention will be explained. "Resin sheet material" refers to the material that constitutes the sheet. Examples of resin 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; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polybutyl succinate, and polyethylene-2,6-naphthalate; polycarbonate resins; polyarylate resins; polyacetal resins; polyphenylene sulfide resins; fluororesins such as tetrafluoroethylene resin, trifluoroethylene resin, trifluorochloroethylene resin, tetrafluoroethylene-hexafluoropropylene copolymer, and vinylidene fluoride resin; acrylic resins; methacrylic resins; polyacetal resins; polyglycolic acid resins; and polylactic acid resins, which can be fluidized by dissolving or melting them in a solvent. These thermoplastic resins can be homopolymers, copolymers, or blends of two or more types. Furthermore, various additives such as antioxidants, antistatic agents, crystal nucleating agents, inorganic particles, organic particles, viscosity reducers, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and dopants for adjusting the refractive index may be added to each thermoplastic resin.

[0014] The term "die" refers to a device that discharges and molds a resin sheet material into a sheet-like resin sheet. The term "casting device" refers to a device that conveys a resin sheet discharged from a die downstream while cooling and solidifying it by tightly contacting it. The form of the device is not particularly limited, but examples include a roll or a belt. The term "air knife" refers to a device that blows air to bring a resin sheet into close contact with a casting device. The source of the air is not particularly limited, but examples include a blower and a compressor. The "conveying direction" refers to the direction in which the resin sheet is conveyed by the casting device. The "width direction" refers to the same direction as the width of the resin sheet.

[0015] The "first air outlet" is one of the components of the air knife and refers to an opening that blows out air to bring the resin sheet into close contact with the casting device. The shape of the opening is not particularly limited, but examples include slits and holes. The "exhaust port" is one of the components of the air knife, and refers to an opening that is located upstream of the first air outlet in the conveying direction and that discharges air. The shape of the opening is not particularly limited, but examples include slits and holes. Air may be naturally exhausted to the atmosphere, or it may be forced to be exhausted by suction. The power source for suction is not particularly limited, but examples include a blower and a vacuum pump. The "second air outlet" is one of the components of the air knife, and is an opening that is located upstream of the exhaust port in the conveying direction and blows out air. When observed from the width direction, the air blowing direction of the second air outlet is inclined downstream in the conveying direction from the direction perpendicular to the surface of the casting device. The shape of the opening is not particularly limited, but examples include slits and holes. The "air blowing direction" refers to the direction in which air is blown out from the first or second air outlet. [Effects of the Invention]

[0016] According to the resin sheet manufacturing apparatus and manufacturing method of the present invention, high adhesion can be achieved without vibration of the resin sheet, and the resin sheet can be manufactured stably. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is an enlarged view of the vicinity of an air knife of the resin sheet manufacturing apparatus according to the first embodiment of the present invention, and is a cross-sectional view perpendicular to the width direction. [Figure 2] FIG. 10 is an enlarged view of the vicinity of an air knife of a resin sheet manufacturing apparatus according to a second embodiment of the present invention, and is a cross-sectional view perpendicular to the width direction. [Figure 3] FIG. 10 is an enlarged view of the vicinity of an air knife of a resin sheet manufacturing apparatus according to a third embodiment of the present invention, and is a cross-sectional view perpendicular to the width direction. [Figure 4] FIG. 1 is an enlarged view of the vicinity of an air knife in a typical resin sheet manufacturing device, and is a cross-sectional view perpendicular to the width direction. [Figure 5] FIG. 1 is an enlarged view of the vicinity of the air knife of the film / sheet forming device of Patent Document 1, and is a cross-sectional view perpendicular to the width direction. [Figure 6] FIG. 1 is an enlarged view of the vicinity of an air knife in the resin film manufacturing device of Patent Document 2, and is a cross-sectional view perpendicular to the width direction. [Figure 7] FIG. 1 is a side view of a typical resin sheet manufacturing apparatus. DETAILED DESCRIPTION OF THE INVENTION

[0018] The present invention will be described in detail below, but is not limited to the embodiments including the following examples. Figures 1 to 3 are diagrams showing a resin sheet manufacturing apparatus 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.

[0019] [Embodiment 1] A resin sheet manufacturing device according to a first embodiment of the present invention will be described. FIG. 1 is an enlarged view of the vicinity of the air knife in the first embodiment, taken along a cross-sectional view perpendicular to the width direction. As shown in FIG. 1, in this embodiment, the air knife 4 is provided, on the surface facing the casting device 2, with a first air outlet 6, an exhaust port 7, and a second air outlet 8, in that order from the downstream side in the conveyance direction. When observed from the width direction, the air blowing direction of the second air outlet 8 (the direction in which air 11 is blown out) is inclined downstream in the conveyance direction relative to the direction perpendicular to the surface of the casting device 2.

[0020] The method for manufacturing a resin sheet in this embodiment is as follows: A resin sheet material is discharged from a nozzle toward a casting device 2 as a resin sheet 3. Air is blown toward the resin sheet 3 from a first air outlet 6 to adhere the resin sheet 3 to the casting device 2, and the resin sheet 3 is cooled and solidified while being transported by the casting device 2. At this time, air is blown from a second air outlet 8 so as to collide with air blown from the first air outlet 6 that is flowing upstream in the transport direction, and the air blown from the second air outlet 8 that has been blown from the first air outlet 6 and is flowing upstream in the transport direction is sucked in from an exhaust port 7.

[0021] The air flow will be described in detail with reference to Figure 1. The flow of air 10a is stopped by colliding air 11 blown out from second air outlet 8 with air 10a blown out from first air outlet 6, which is directed upstream in the conveyance direction. However, if this is left as it is, the colliding air 10a and air 11 will flow toward air 10, obstructing the flow of air 10 and reducing adhesion. Therefore, the colliding air 10a and air 11 are exhausted from exhaust port 7. This suppresses vibration of the resin sheet caused by air 10a while also preventing a decrease in adhesion.

[0022] In this way, the resin sheet manufacturing apparatus of this embodiment can suppress vibration of the resin sheet while achieving high adhesion.

[0023] By tilting the air blowing direction of the second air outlet 8 downstream in the conveying direction from the direction perpendicular to the surface of the casting apparatus 2, most of the air 11 flows downstream in the conveying direction, making it possible to stop the flow of air 10a with a small amount of air 11 and further reducing the amount of air 11 flowing upstream in the conveying direction. It is more preferable that the air blowing direction of the second air outlet 8 be tilted 20 to 70 degrees downstream in the conveying direction from the direction perpendicular to the surface of the casting apparatus 2.

[0024] [Embodiment 2] A resin sheet manufacturing device according to a second embodiment of the present invention will be described. FIG. 2 is an enlarged view of the vicinity of the air knife in the second embodiment, taken along a cross-sectional view perpendicular to the width direction. As shown in FIG. 2, this embodiment differs from the first embodiment in that the air blowing direction (the direction in which air 10 is blown out) from the first air outlet 6 is perpendicular to the surface of the casting device 2. This is because the air blowing direction from the first air outlet 6 is closer to a direction perpendicular to the surface of the casting device 2 than the air blowing direction from the second air outlet 8. The rest of the configuration is the same as in the first embodiment, and the effects of the air 11 blown out from the second air outlet 8 stopping the flow of the air 10a and the air 10a and 11 colliding with each other and being discharged from the exhaust port 7 are also the same as in the first embodiment.

[0025] With this configuration, the air 10 collides with the resin sheet 3 perpendicular to the surface of the casting device 2, so that the resin sheet 3 adheres with a strong force to the casting device 2. It is more preferable that the air blowing direction of the first blowing outlet is closer to the direction perpendicular to the surface of the casting device by 20 to 70 degrees than the air blowing direction of the second blowing outlet.

[0026] [Embodiment 3] A resin sheet manufacturing device according to a third embodiment of the present invention will be described. FIG. 3 is an enlarged view of the vicinity of the air knife in the third embodiment, taken along a cross-sectional view perpendicular to the width direction. As shown in FIG. 3, this embodiment differs from the first embodiment in that the shortest distance 31 between the edge of the opening of the second air outlet 8 and the casting device 2 is shorter than the shortest distance 30 between the edge of the opening of the first air outlet 6 and the casting device 2. The rest of the configuration is the same as in the first embodiment, and the effects of the air 11 blown out from the second air outlet 8 stopping the flow of the air 10a and the air 10a and 11 colliding with each other from the exhaust port 7 are also the same as in the first embodiment.

[0027] By adopting such a configuration, the entire air 11 can more easily flow downstream in the transport direction, and the effect of stopping the flow of the air 10a by the air 11 is enhanced. It is more preferable that the shortest distance 31 is 0.2 to 0.8 times the shortest distance 30. [Example]

[0028] An example of resin sheet production using the resin sheet production apparatus of the present invention will be described below.

[0029] [Example 1] The resin sheet was actually manufactured using a resin sheet manufacturing apparatus, and the results of evaluating air entrapment due to poor adhesion and thickness unevenness due to vibration of the resin sheet will be described. Specific sheet manufacturing conditions and evaluation methods in this embodiment are as follows.

[0030] (1) Resin sheet material Linear polypropylene with an MFR of 5.0 g / 10 min. The MFR was measured at a temperature of 230°C and a load of 2.16 kg in accordance with JIS K 7210-1 (2014).

[0031] (2) Extrusion The resin sheet material was extruded at a flow rate of 250 kg / h using an extruder, passed through a gear pump and a filter, and then fed to a die. The temperature of the device up to the die was 250°C.

[0032] (3) Base The resin sheet material was discharged as a resin sheet from a discharge port having a width of 500 mm and a gap of 2 mm, and formed into a sheet shape.

[0033] (4) Casting equipment The resin sheet was brought into close contact with a roll whose temperature was adjusted to 90°C, and then cooled and solidified.

[0034] (5) Air knife Air was blown from the first outlet toward the point where the resin sheet was placed on the casting machine, and from the second outlet as well. Air was also blown from the exhaust port. The first outlet had a 480 mm wide slit with a 1 mm gap, and the air outlet was tilted 40° downstream in the conveying direction from the direction perpendicular to the surface of the casting machine. The shortest distance between the edge of the opening and the casting machine was 6 mm. The blower was adjusted so that the air flow velocity was 100 m / s. The exhaust port had a 480 mm wide slit with a 6 mm gap and was open to the atmosphere. The second outlet had a 480 mm wide slit with a 1 mm gap, and the air outlet was tilted 40° downstream in the conveying direction from the direction perpendicular to the surface of the casting machine. The shortest distance between the edge of the opening and the casting machine was 6 mm. The blower was adjusted so that the air flow velocity was 40 m / s.

[0035] (6) Air entrapment evaluation If the adhesion force by the air knife is weak, air gets trapped between the resin sheet and the casting device, causing many small dents on the surface of the resin sheet. Air trapping was evaluated by visually inspecting the sampled sheet and counting the number of dents within a 10cm square area.

[0036] (7) Thickness unevenness evaluation If the resin sheet vibrates between being discharged from the die and coming into contact with the casting device, it will have thickness unevenness in the conveyance direction. Thickness unevenness was evaluated by measuring the thickness of a sampled sheet 1 m in the conveyance direction using a tabletop offline contact type thickness measuring device TOF-4R05 manufactured by Yamabun Denki Co., Ltd., and calculating the measured value (maximum value - minimum value) / average thickness x 100 [%].

[0037] [Example 2] A sheet was obtained in the same manner as in Example 1, except that the air blowing direction of the first blowing port was changed to a state inclined by 20 degrees downstream in the conveying direction from the direction perpendicular to the surface of the casting device.

[0038] [Example 3] A sheet was obtained in the same manner as in Example 1, except that the air blowing direction of the first blowing port was changed to be perpendicular to the surface of the casting device.

[0039] [Example 4] A sheet was obtained in the same manner as in Example 1, except that the shortest distance between the edge of the opening of the second outlet and the casting device was changed to 3 mm.

[0040] [Comparative Example 1] A sheet was collected in the same manner as in Example 1, except that the air knife did not have an exhaust port and a second blowout port.

[0041] Comparative Example 2 A sheet was collected in the same manner as in Example 1, except that the air knife did not have an exhaust port.

[0042] [Evaluation results] In Example 1, there were 32 air entrapments and thickness unevenness was 8%. The effects of each Example and Comparative Example were evaluated based on the degree to which air entrapment and thickness unevenness increased or decreased compared to Example 1.

[0043] In Example 2, which used an air knife in which the air blowing direction of the second blowing port was tilted downstream in the conveying direction more than the air knife in Example 1, there were 33 air traps and thickness unevenness was 4%, which was less uneven in thickness than in Example 1.

[0044] In Example 3, in which the air blowing direction from the first blowing outlet was closer to the direction perpendicular to the cast surface than the air knife in Example 1, in other words, an air knife was used in which the air blowing direction from the first blowing outlet was closer to the direction perpendicular to the cast surface than the air blowing direction from the second blowing outlet, there were 15 air entrapments and thickness unevenness was 9%, which means that air entrapment was reduced while maintaining thickness unevenness equivalent to that of Example 1.

[0045] In Example 4, in which the shortest distance between the edge of the opening of the second air outlet and the casting device was shorter than that of the air knife in Example 1 and an air knife shorter than the shortest distance between the edge of the opening of the first air outlet and the casting device was used, there were 31 air entrapments and thickness unevenness was 3%, which was less than that of Example 1.

[0046] In Comparative Example 1, which used an air knife without an exhaust port and a second blowing port, there were 35 air entrapments and a thickness unevenness of 25%, which was the same as in Example 1, but the thickness unevenness was significantly worse.

[0047] In Comparative Example 2, in which an air knife without an exhaust port was used, there were 52 air entrapments and a thickness variation of 10%, which was the same thickness variation as in Example 1, but the air entrapment was significantly worse. [Industrial Applicability]

[0048] The present invention is not limited to a manufacturing apparatus and manufacturing method for a resin sheet, but can also be applied to an air knife for drying or removing foreign matter, but the range of application is not limited to these. [Explanation of symbols]

[0049] 1 nozzle 2 Casting equipment 3 Resin sheet 4 Air Knife 6 First air outlet 7. Exhaust port 8, 8a, 8b Second air outlet 10, 10a, 10b, 11 Air flow 30 Shortest distance between the edge of the opening of the first air outlet and the casting device 31 Shortest distance between the edge of the second air outlet opening and the casting device

Claims

1. a die that discharges the resin sheet material as a resin sheet; a casting device that cools and solidifies the resin sheet discharged from the die while transporting it; an air knife that blows air toward the resin sheet to bring the resin sheet into close contact with the casting device; the air knife has, on a surface facing the casting device, a first air outlet, an exhaust port, and a second air outlet, in this order from the downstream side in the conveyance direction; When observed from the width direction, the air blowing direction of the second blowing outlet is inclined downstream in the conveying direction with respect to a direction perpendicular to the surface of the casting device. Resin sheet manufacturing equipment.

2. 2. The resin sheet manufacturing device according to claim 1, wherein, when observed from the width direction, the air blowing direction of the first air outlet is closer to a direction perpendicular to the surface of the casting device than the air blowing direction of the second air outlet.

3. 2. The resin sheet manufacturing device according to claim 1, wherein the shortest distance between the edge of the opening of the second blow-out port and the casting device is shorter than the shortest distance between the edge of the opening of the first blow-out port and the casting device.

4. Using the resin sheet manufacturing device according to any one of claims 1 to 3, The resin sheet material is discharged from the die toward the casting device as a resin sheet; air is blown from the first blowing port toward the resin sheet to bring the resin sheet into close contact with the casting device; A resin sheet manufacturing method comprising: cooling and solidifying the resin sheet while transporting it in the casting device, air is blown out from the second air outlet so as to collide with air flowing toward the upstream side in the conveying direction, out of the air blown out from the first air outlet; the air blown out from the first air outlet and flowing toward the upstream side in the conveying direction and the air blown out from the second air outlet are sucked through the exhaust port; A method for manufacturing a resin sheet.

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