Manufacturing equipment for resin sheets

Abstract

The present invention provides a resin sheet manufacturing apparatus and manufacturing method that can stably produce high-quality sheets. [Solution] The resin sheet manufacturing apparatus of the present invention comprises a nozzle for dispensing resin sheet material as a resin sheet, a casting apparatus for conveying and cooling the resin sheet dispensed from the nozzle and solidifying it, and an air knife for blowing air toward the resin sheet in order to make the resin sheet adhere to the casting apparatus, wherein the air knife has, on the surface facing the casting apparatus, an air outlet for forcibly blowing air, an air inlet for forcibly blowing air or for natural air supply, and an exhaust port, in that order from the downstream side in the conveying direction.

Description

[[Technical Field]]

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

[0002] First, a general apparatus for manufacturing a resin sheet will be described. Fig. 8 is a side view of a general apparatus for manufacturing a resin sheet. As shown in Fig. 8, the general manufacturing apparatus includes a die that discharges a resin sheet material as a resin sheet, and a casting device that cools and solidifies the resin sheet discharged from the die while conveying the resin sheet. The apparatus for manufacturing a resin sheet shown in Fig. 8 further includes an air knife that blows air toward the resin sheet to bring the resin sheet into close contact with the casting device.

[0003] Here, the flow of air blown from the air knife will be described. Fig. 5 is an enlarged view of the vicinity of an air knife in a general resin sheet manufacturing apparatus, and is a cross-sectional view perpendicular to the width direction of the resin sheet (hereinafter abbreviated as "width direction"). As shown in Fig. 5, the air knife blows air from an air outlet to bring the resin sheet into close contact with the casting device. After the air collides with the resin sheet, it splits into air that flows upstream in the conveyance direction of the resin sheet (hereinafter abbreviated as "conveyance direction") and air that flows downstream in the conveyance direction. If the airflow volume of the upstream air is large, the resin sheet before it is discharged from the die and brought into close contact with the casting device will vibrate, resulting in unstable film formation such as thickness unevenness.

[0004] As a technique for suppressing this vibration of the resin sheet, Patent Document 1 discloses a sheet forming apparatus provided with an air passage for the purpose of reducing air flowing upstream in the conveyance direction. Fig. 6 is an enlarged view of the vicinity of an air knife in the sheet forming apparatus of Patent Document 1, and is a cross-sectional view perpendicular to the width direction. As shown in Fig. 6, in the apparatus of Patent Document 1, part of the air flowing upstream in the conveyance direction flows into the air passage, whereby vibration of the resin sheet caused by the upstream air can be suppressed. [[Prior Art Documents]] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-open No. 61-121923 [Overview of the project] [Problems that the invention aims to solve]

[0006] The sheet molding apparatus of Patent Document 1 can suppress vibration of the resin sheet 3 due to air 10a, but it can cause vibration of the resin sheet 3 due to vortices. Figure 7 is a partially enlarged view of the area around the outlet and air passage of Figure 6, and is a cross-sectional view perpendicular to the width direction. As shown in Figure 7, in the sheet molding apparatus of Patent Document 1, the pressure decreases in the space surrounded by the air 10 blown out from the outlet 6, the air 10a flowing upstream in the conveying direction, and the air 12 flowing in the air passage 8, generating a vortex 10c, and this vortex 10c causes vibration of the resin sheet 3.

[0007] 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 force of the resin sheet to the casting apparatus while suppressing vibration of the resin sheet. [Means for solving the problem]

[0008] [1] The present invention provides a resin sheet manufacturing apparatus that solves the above problem. A nozzle that dispenses resin sheet material as a resin sheet, A casting apparatus that cools and solidifies the resin sheet extruded from the nozzle while transporting it, The system includes an air knife that blows air toward the resin sheet in order to make the resin sheet adhere to the casting device, The air knife described above has, on the surface facing the casting device, an air outlet for forcibly blowing out air, an air inlet for forcibly blowing out air or for natural air supply, and an exhaust port, in that order from the downstream side in the conveying direction.

[0009] The resin sheet manufacturing apparatus of the present invention is preferably in the form of [2] or [3] below. [2] The resin sheet manufacturing apparatus of [1], wherein, when observed from the width direction, the air blowing direction of the air intake port is inclined downstream in the conveying direction rather than perpendicular to the surface of the casting apparatus. [3] A resin sheet manufacturing apparatus according to [1] or [2], wherein the shortest distance between the upstream edge of the opening of the air intake port in the conveying direction and the casting device is shorter than the shortest distance between the downstream edge of the opening of the air intake port in the conveying direction and the casting device.

[0010] [4] The present invention provides a method for manufacturing a resin sheet that solves the above problems, using any of the resin sheet manufacturing apparatuses described in [1] to [3] above. The resin sheet material is extruded from the nozzle as a resin sheet towards the casting device. Air is blown from the above-mentioned outlet toward the above-mentioned resin sheet to make the above-mentioned resin sheet adhere closely to the above-mentioned casting device. The resin sheet is transported and cooled while being solidified in the above casting apparatus. A method for manufacturing a resin sheet, comprising sucking in air that has been blown out from the above-mentioned exhaust port and flowed upstream in the conveying direction from the above-mentioned outlet, Air is supplied from the above-mentioned air intake to the space between the above-mentioned air knife and the above-mentioned resin sheet, between the above-mentioned air outlet and the above-mentioned exhaust port.

[0011] [Explanation of Terms] The meaning of each term used in this invention will be explained.

[0012] "Resin sheet material" refers to the material that makes up the sheet. As resin sheet material, for example, 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, trifluoroethylene chloride resin, tetrafluoroethylene-hexafluoropropylene copolymer, and vinylidene fluoride resin; acrylic resins; methacrylic resins; polyacetal resins; polyglycolic acid resins; and polylactic acid resins can be used in a fluidized form by dissolving or melting them in a solvent. Furthermore, these thermoplastic resins may be homopolymers, copolymers, or blends of two or more types. Furthermore, various additives may be added to each thermoplastic resin, such as antioxidants, antistatic agents, nucleating agents, inorganic particles, organic particles, viscosity reducers, heat stabilizers, lubricants, infrared absorbers, ultraviolet absorbers, and doping agents for refractive index adjustment.

[0013] A "die" refers to a device that extrudes resin sheet material into a sheet-like resin sheet and then molds it. A "casting device" is a device that transports a resin sheet, extruded from a nozzle, downstream while cooling and solidifying it by ensuring it is tightly sealed. While its form is not particularly limited, examples include rolls and belts. "Conveying direction" refers to the direction in which the resin sheet is conveyed by the casting device. "Width direction" refers to the direction that is the same as the width of the resin sheet.

[0014] An "air knife" is a device that uses air to press a resin sheet tightly against a casting machine.

[0015] The term "blow outlet" refers to one of the components of an air knife, which is an opening that blows out air for bringing a resin sheet into close contact with a casting device. The shape of the opening is not particularly limited, and examples thereof include a slit shape and a porous shape. Air is forcibly blown out from some supply source, and is not blown out by natural air supply. The air supply source is not particularly limited, and examples thereof include a blower and a compressor.

[0016] The term "exhaust outlet" refers to one of the components of an air knife, which is an opening located upstream of the blow outlet in the conveying direction and discharges air. The shape of the opening is not particularly limited, and examples thereof include a slit shape and a porous shape. The power source for exhaust is not particularly limited, and examples thereof include a blower and a vacuum pump. The shortest distance between the exhaust outlet and the blow outlet is preferably 5 to 100 mm.

[0017] The term "air supply inlet" refers to one of the components of an air knife, which is an opening located upstream of the blow outlet in the conveying direction and downstream of the exhaust outlet in the conveying direction, and supplies air. The shape of the opening is not particularly limited, and examples thereof include a slit shape and a porous shape. The air supply source is not particularly limited, and examples thereof include a blower and a compressor, and natural air supply from the atmosphere is also acceptable. In the case of natural air supply, a mechanism capable of adjusting the air supply flow rate may be provided.

[0018] The term "air blowing direction" refers to the direction in which the blow outlet or the air supply inlet blows out air. Effects of the Invention

[0019] According to the apparatus and method for manufacturing a resin sheet of the present invention, high adhesion can be achieved without vibration of the resin sheet, and the resin sheet can be stably manufactured. Brief Description of the Drawings

[0020] [Figure 1] It is an enlarged view of the vicinity of the air knife of the resin sheet manufacturing apparatus according to Embodiment 1 of the present invention, and is a cross-sectional view perpendicular to the width direction. [Figure 2] It is a partially enlarged view of the vicinity of the blow outlet, the air supply inlet and the exhaust outlet in Fig. 1. [Figure 3] This is an enlarged view of the area around the air outlet, air intake, and exhaust port of the air knife of the resin sheet manufacturing apparatus according to Embodiment 2 of the present invention, and is a cross-sectional view perpendicular to the width direction. [Figure 4] This is an enlarged view of the area around the air outlet, air intake, and exhaust port of the air knife of the resin sheet manufacturing apparatus according to Embodiment 3 of the present invention, and is a cross-sectional view perpendicular to the width direction. [Figure 5] This is a magnified view of the area around the air knife in a typical resin sheet manufacturing machine, and it is a cross-sectional view perpendicular to the width direction. [Figure 6] This is an enlarged view of the area around the air knife of the sheet forming apparatus described in Patent Document 1, and is a cross-sectional view perpendicular to the width direction. [Figure 7] Figure 6 is a magnified view of a portion of the area around the air outlet and air passage. [Figure 8] This is a side view of a typical resin sheet manufacturing apparatus. [Modes for carrying out the invention]

[0021] The present invention will be described in detail below, but the present invention is not limited to embodiments including the following examples. Figures 1 to 4 are diagrams relating to a resin sheet manufacturing apparatus of the present invention. Note that components having the same use and function as those in the prior art may have the same reference numerals.

[0022] [Embodiment 1] A resin sheet manufacturing apparatus according to Embodiment 1 of the present invention will be described. Figure 1 is an enlarged view of the area around the air knife of Embodiment 1, and Figure 2 is a partially enlarged view of the area around the air outlet, air inlet, and exhaust port of Figure 1, both of which are cross-sectional views perpendicular to the width direction. As shown in Figure 1, in this embodiment, the air knife 4 is provided with an air outlet 6, an air inlet 7, and an exhaust port 8 on the surface facing the casting device 2, in order from the downstream side in the conveying direction.

[0023] The method for manufacturing the resin sheet in this embodiment is as follows: Resin sheet material is discharged from a nozzle as a resin sheet 3 toward the casting device 2. Air 10 is blown from the outlet 6 toward the resin sheet 3 to make the resin sheet 3 adhere closely to the casting device 2, and the resin sheet 3 is cooled and solidified while being transported in the casting device 2. As shown in Figure 2, the air 10a blown from the outlet 6 and flowing upstream in the transport direction is exhausted from the exhaust port 8 so as not to vibrate the resin sheet 3. At this time, the pressure decreases in the space surrounded by air 10, air 10a and the air 12 exhausted from the exhaust port 8. If left as is, vortices may be generated in this low-pressure space, causing new vibrations in the resin sheet 3. Therefore, the generation of vortices is suppressed by supplying air 11 from the air intake port 7 between this low-pressure space, that is, between the outlet 6 and the exhaust port 8. Here, in order to stably supply a constant amount of air 11 from the air intake port 7, it is more preferable to forcibly exhaust from the exhaust port 8 using a blower or the like.

[0024] Thus, the resin sheet manufacturing apparatus of this embodiment can suppress vibrations in the resin sheet and stably manufacture resin sheets.

[0025] [Embodiment 2] A resin sheet manufacturing apparatus according to Embodiment 2 of the present invention will now be described. Figure 3 is an enlarged view of the vicinity of the air outlet, air intake, and exhaust port of the air knife of Embodiment 2, and is a cross-sectional view perpendicular to the width direction. As shown in Figure 3, the difference between this embodiment and Embodiment 1 is that the air blowing direction of the air intake 7 (the direction in which the air 11 is blown out) is inclined downstream in the conveying direction rather than perpendicular to the surface of the casting apparatus 2. The other configurations are the same as in Embodiment 1, and the fact that the air 11 supplied from the air intake 7 suppresses vortices is also the same as in Embodiment 1.

[0026] Since the air 11 tends to flow towards the exhaust port 8, that is, the upstream side in the conveying direction, this configuration allows a sufficient amount of air 11 to be supplied to the downstream side in the conveying direction, that is, the outlet 6 side, thereby further suppressing vortices. It is more preferable that the air outlet direction of the air supply port 7 is inclined 20 to 70 degrees downstream in the conveying direction rather than perpendicular to the surface of the casting device 2.

[0027] [Embodiment 3] A resin sheet manufacturing apparatus according to Embodiment 3 of the present invention will now be described. Figure 4 is an enlarged view of the vicinity of the air outlet, air intake, and exhaust port of the air knife of Embodiment 3, and is a cross-sectional view perpendicular to the width direction. As shown in Figure 4, the difference between this embodiment and Embodiment 1 is that the shortest distance 30 between the upstream edge of the opening of the air intake 7 in the conveying direction and the casting device 2 is shorter than the shortest distance 31 between the downstream edge of the opening of the air intake 7 in the conveying direction and the casting device 2. The other configurations are the same as in Embodiment 1, and the fact that the air 11 blown out from the air intake 7 suppresses vortices is also the same as in Embodiment 1.

[0028] Since the air 11 tends to flow towards the exhaust port 8 side, that is, the upstream side in the conveying direction, this configuration allows a sufficient amount of air 11 to be supplied to the downstream side in the conveying direction, that is, the outlet 6 side, and further suppresses vortices. It is more preferable that the shortest distance 30 is 0.2 to 0.8 times the shortest distance 31. [Examples]

[0029] The following shows an example of resin sheet manufacturing using the resin sheet manufacturing apparatus according to the present invention.

[0030] [Example 1] This section describes the results of actually manufacturing a resin sheet using a resin sheet manufacturing apparatus and evaluating the thickness variations caused by vibration in the resin sheet. The specific sheet manufacturing conditions and evaluation method in this embodiment are as follows.

[0031] (1) Resin sheet material Linear polypropylene, MFR 5.0 g / 10 min. Here, MFR was measured in accordance with JIS K 7210-1 (2014) at a temperature of 230°C and a load of 2.16 kg.

[0032] (2) Extrusion A resin sheet material was extruded using an extruder at a flow rate of 250 kg / h, and after passing through a gear pump and filter, it was supplied to a die. The temperature of the apparatus up to the die was 250°C.

[0033] (3) Nozzle The resin sheet material was extruded as a resin sheet from an outlet with a width of 500 mm and a gap of 2 mm, and then molded into a sheet shape.

[0034] (4) Casting device The resin sheet was pressed tightly onto a roll that was temperature-controlled to 90°C, and then cooled and solidified.

[0035] (5) Air knife The air knife has an air outlet, an air inlet, and an air exhaust port on the side facing the casting device, arranged in order from the downstream side in the conveying direction. Air was blown from the air outlet towards the point where the resin sheet made contact with the casting device, air was also blown from the air inlet, and air was discharged from the air exhaust port. The air outlet had a slit shape with a width of 480 mm and a gap of 1 mm, and the air blowing direction was inclined 40 degrees downstream in the conveying direction rather than perpendicular to the surface of the casting device, and the blower was adjusted so that the air velocity blown out of the slit was 100 m / s. The air inlet had a slit shape with a width of 480 mm and a gap of 1 mm, and the air blowing direction was perpendicular to the surface of the casting device, and the blower was adjusted so that the air velocity blown out of the slit was 20 m / s. The exhaust port had a slit shape with a width of 480 mm and a gap of 1 mm, and the blower was adjusted so that the air velocity exhausted from the slit was 40 m / s. The air knife was installed so that the shortest distance between the upstream edge of the air intake opening in the conveying direction and the casting device was 5 mm, and the shortest distance between the downstream edge of the air intake opening in the conveying direction and the casting device was also 5 mm.

[0036] (6) Thickness unevenness evaluation If the resin sheet vibrates between being extruded from the nozzle and adhering to the casting device, thickness variations occur in the conveying direction. Thickness variations were evaluated using a Yamabun Electric Co., Ltd. TOF-4R05 desktop offline contact thickness measuring device, measuring the thickness of a sampled sheet over a distance of 1m in the conveying direction, and calculating the result as (maximum value - minimum value) / average thickness × 100 [%].

[0037] [Example 2] Except for changing the upstream side of the air intake to open to the atmosphere, the sheet was collected in the same manner as in Example 1.

[0038] [Example 3] The sheet was collected in the same manner as in Example 1, except that the direction of air blowing from the air intake was changed to be tilted 40 degrees downstream in the conveying direction from the direction perpendicular to the surface of the casting device.

[0039] [Example 4] Except for changing the shortest distance between the upstream edge of the air intake opening in the transport direction and the casting device to 3 mm, the sheet was sampled in the same manner as in Example 1.

[0040] [Comparative Example 1] The sheet was collected in the same manner as in Example 1, except that the air knife did not have an air intake.

[0041] [Evaluation Results] Example 1 had a thickness variation of 8%. The effects of each example and comparative example were evaluated by the extent to which air entrapment and thickness variation increased or decreased compared to Example 1.

[0042] Example 2, which used an air knife with the upstream side of the air intake vented to the atmosphere, showed a thickness variation of 8%, which was equivalent to the result in Example 1.

[0043] In Example 3, which used an air knife in which the air blowing direction from the air intake was tilted 40 degrees downstream in the conveying direction rather than perpendicular to the surface of the casting device, the thickness variation was 4%, which was a reduction in thickness variation compared to Example 1.

[0044] In Example 4, which used an air knife where the shortest distance between the upstream edge of the air intake opening in the conveying direction and the casting device was shorter than the shortest distance between the downstream edge of the air intake opening in the conveying direction and the casting device, the thickness variation was 3%, which is a reduction in thickness variation compared to Example 1.

[0045] Comparative Example 1, which used an air knife without an air intake, had a thickness unevenness of 25%, which was significantly worse than Example 1. [Industrial applicability]

[0046] The present invention is not limited to manufacturing apparatus and methods for resin sheets, but can also be applied to air knives for drying and foreign matter removal, although its scope of application is not limited to these. [Explanation of Symbols]

[0047] 1. Nozzle 2 Casting device 3. Resin sheet 4 Air Knife 6 Air outlet 7 Air supply port 8 exhaust vents 10, 10a, 10b, 11, 11a, 11b, 12 Airflow 30 The shortest distance between the upstream edge of the air intake opening in the transport direction and the casting device. 31 The shortest distance between the downstream edge of the air intake opening in the transport direction and the casting device.

Claims

1. A nozzle that dispenses resin sheet material as a resin sheet, A casting apparatus that cools and solidifies the resin sheet discharged from the nozzle while transporting it, The system includes an air knife that blows air toward the resin sheet in order to make the resin sheet adhere to the casting device, The air knife has, on the surface facing the casting device, an air outlet for forcibly blowing out air, an air inlet for forcibly blowing out air or for natural air supply, and an exhaust port, in that order from the downstream side in the conveying direction. Manufacturing equipment for resin sheets.

2. Observed from the width direction, the air outlet direction of the air intake is inclined downstream in the conveying direction rather than perpendicular to the surface of the casting device. A manufacturing apparatus for resin sheets according to claim 1.

3. The shortest distance between the upstream edge of the air intake opening in the conveying direction and the casting device is shorter than the shortest distance between the downstream edge of the air intake opening in the conveying direction and the casting device. A manufacturing apparatus for resin sheets according to claim 1.

4. Using a resin sheet manufacturing apparatus according to any one of claims 1 to 3, The resin sheet material is extruded from the nozzle as a resin sheet toward the casting device. Air is blown from the aforementioned outlet toward the resin sheet to make the resin sheet adhere closely to the casting device. The resin sheet is transported and cooled in the aforementioned casting apparatus to solidify it. A method for manufacturing a resin sheet, comprising sucking air that has been blown out from the exhaust port and flowed upstream in the conveying direction, Air is supplied from the aforementioned air intake to the space between the air knife and the resin sheet between the air outlet and the exhaust port. A method for manufacturing resin sheets.

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