Method for producing polycarbonate resin molded article

Abstract

The present invention relates to a method for producing a molded article of a polycarbonate resin in which a polycarbonate resin is molded using an injection molding device, the method comprising a step for feeding powder particles of the polycarbonate resin into the injection molding device in a starved state; a step for generating a plasticized resin by plasticizing the powder body in an injection molding device; and a step for molding a molded article from the plasticized resin, wherein the moisture content of the powder supplied to the injection molding device in a starved state is 0.3 wt% or less.

Description

Technical Field

[0001] The present invention relates to a method for producing a polycarbonate resin molded product, and more particularly to a method for producing a polycarbonate resin molded product by feeding a polycarbonate resin powder or granule into an injection molding device in a starved state. Background Art

[0002] Conventionally, various methods for producing polycarbonate resin molded articles have been proposed, as shown in Patent Documents 1 to 3 and the like.

[0003] Patent document 1 describes a method for producing a molded body by feeding resin pellets in a hungry state using a vented injection molding device (its abstract and paragraphs

[0017] ,

[0018] and

[0026] ). Patent document 2 describes a method for producing a polycarbonate resin molding material by feeding polycarbonate resin powder particles to an extruder in a hungry state to produce a pellet-shaped molding material (its paragraphs

[0015] ,

[0030] and

[0035] ). Patent document 3 describes a method for producing a polycarbonate resin composition by feeding pellets to an injection molding device in a hungry state when the polycarbonate resin composition is pelletized (its claims 1 and 2).

[0004] Prior art literature Patent Literature Patent Document 1: International Publication No. 2019 / 9362 Patent Document 2: Japanese Patent Application Publication No. 2011-37164 Patent Document 3: Japanese Patent Application Publication No. 2016-165817 Summary of the invention

[0005] Problems to be solved by the invention Polycarbonate resin molded products manufactured using conventional manufacturing methods have always had the problem of bubbles (silver streaks) contained in the molded body.

[0006] Therefore, an object of the present invention is to provide a method for producing a polycarbonate resin molded article containing no bubbles in the molded article.

[0007] Technical solutions to solve problems Various embodiments of the present invention are shown below.

[0008] [Example 1 of Embodiment] A method for manufacturing a molded product of a polycarbonate resin, wherein the method uses an injection molding device to mold the polycarbonate resin, and is characterized by comprising: The step of feeding the polycarbonate resin powder and granules into the injection molding device in a hungry state; The step of plasticizing the powder and granules in the injection molding device to produce a plasticized resin; and The step of molding the plasticized resin into the molded product. The water content of the powder or granule supplied to the injection molding device in the starved feed is 0.3 wt % or less.

[0009] [Implementation Example 2] The method according to Implementation Example 1 is characterized in that: At least 50% by weight of the powder or granule supplied in the starved state feed has a particle shape of 200 to 2000 μm.

[0010] [Implementation Example 3] The method according to Implementation Example 2 is characterized in that: The specific surface area of ​​the above-mentioned powder and granules supplied in the above-mentioned starved state feed is 0.01m 2 / g or above.

[0011] [Implementation Example 4] The method according to Implementation Example 1 is characterized in that: The powder or granule supplied in the above-mentioned hungry state feed is a powder or granule in the form of crumbs or fine particles.

[0012] [Implementation Example 5] The method according to Implementation Example 1 is characterized in that: The moisture content of the powder or granule supplied in the starved state feed is 0.01 wt % or more.

[0013] [Implementation Example 6] The method according to Implementation Example 5 is characterized in that: The moisture content of the powder or granule supplied in the starved state feed is 0.06 wt % or more.

[0014] [Implementation Example 7] The method according to Implementation Example 1 is characterized in that: The moisture content of the powder or granule supplied in the starved state feed is 0.20 wt % or less.

[0015] [Implementation Example 8] The method according to Implementation Example 1 is characterized in that: The water content of the powder or granule supplied in the starved feed is 0.01 wt % or more and 0.20 wt % or less.

[0016] [Implementation Example 9] The method according to Implementation Example 1 is characterized in that: The specific surface area of ​​the above-mentioned powder and granules supplied in the above-mentioned starved state feed is 0.01m 2 / g or more, and 50 wt % or more of the powder or granule supplied in the starved state feed has a particle size of 200 to 2000 μm.

[0017] [Implementation Example 10] The method according to Implementation Example 1 is characterized in that: The feeder in the injection molding device is any one of a screw type, a vibration type, a belt type, a table type and a rotary type.

[0018] [Implementation Example 11] The method according to Implementation Example 10 is characterized in that: The screw speed of the above-mentioned screw type hungry feeder in the above-mentioned injection molding device is 20 to 500 rpm.

[0019] [Implementation Example 12] The method according to Implementation Example 1 is characterized in that: In the step of plasticizing the powder or granule, the powder or granule is plasticized for 10 to 60 seconds.

[0020] [Implementation Example 13] The method according to Implementation Example 1 is characterized in that: The injection molding device has a cylinder, and the temperature inside the cylinder is 230 to 360°C.

[0021] [Implementation Example 14] The method according to Implementation Example 13 is characterized in that: A screw is disposed in the barrel, and the rotation speed of the screw is 10 to 200 rpm.

[0022] Effects of the Invention BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a structural diagram of an injection molding device used in the method for producing a polycarbonate resin molded article of the present invention.

[0024] Figure 2 for Figure 1 Structural diagram of a hunger feeding device of an injection molding device.

[0025] Figure 3 This is a structural diagram of an injection molding device with a vent used in the method for producing a polycarbonate resin molded article of the present invention. DETAILED DESCRIPTION

[0026] The following describes a method for producing a polycarbonate resin molded article according to an embodiment of the present invention. Figure 1 Injection molding device 1 or Figure 3 Injection molding device 1 '.

[0027] [Injection molding equipment] First, the injection molding apparatus used in this embodiment will be described.

[0028] The injection molding device 1 includes a barrel 10, a screw 20 accommodated in the barrel 10 and rotatable therein, a feeding device 30 connected to the feed port 10a at the rear end side of the barrel 10 in the injection direction, and a discharge nozzle 40 connected to the front end side of the barrel 10 in the injection direction. The head 20a of the screw 20 is inserted into the discharge nozzle 40. A heater 14 is arranged on the outer peripheral surface of the barrel 10.

[0029] like Figure 2 As shown, the feeding device 30 includes a hopper 32 for receiving the powder or granule 50 and a screw feeder 34 for supplying the powder or granule 50 from the hopper 32 into the barrel 10 through the feed port 10 a.

[0030] because Figure 3 The injection molding device 1' shown has the same structure as the injection molding device 1 except that the barrel 10 is provided with a vent 12 for exhaust, so the description of the same parts is omitted. In the injection molding device 1', a vent 12 is provided at a certain position in the middle part of the length direction of the barrel 1. Although it is not necessary to equip such a vent, such an arrangement will enable volatile components to be discharged from, for example, the vent 12. In this case, in order to efficiently discharge the volatile components from the vent 12, it is preferred to set the vent 12 on the front end side of the barrel 10 compared to the plasticizing zone (rear end side).

[0031] like Figure 3 As shown, the barrel 10 of the injection molding device 1' is composed of a plasticizing zone, a melting and compression zone, and a metering zone from the hopper 32 side (the hungry feeding device 30 side) to the injection direction side of the front end of the device (the outlet side of the extrusion device), and the screw 20 is designed according to the purpose of each zone.

[0032] The plasticizing zone is a zone for melting and plasticizing the powder and granules 50 supplied from the hungry feeding device 30, and in the plasticizing zone, volatile components are generated from the powder and granules 50. The melt compression zone is a zone for further melting and compressing the molten resin from the plasticizing zone to discharge gaseous volatile components, and the vent 12 is preferably provided in this zone. The metering zone is a zone for stabilizing the polycarbonate resin before discharging and performing adjustment to suppress fluctuations in the discharging amount.

[0033] In the injection molding apparatus 1 and 1' used in the present invention, the L / D (length in the extrusion direction / diameter) of the barrel 10 is preferably 10 or more, more preferably 10 to 40, and further preferably 10 to 30. It should be noted that the L / D of the injection molding apparatus used in the embodiment is 20. The length L in the extrusion direction of the barrel 10 refers to the length from the center of the feed port 10a for supplying raw materials such as powder 30 to the barrel 10 to the base end of the head 20a of the screw 20, and the diameter of the barrel 10 refers to the diameter of the cylindrical barrel.

[0034] The length of the plasticizing zone is preferably a region of about 1 / 2 to 7 / 10 of the length L in the extrusion direction of the injection barrel 10. In addition, the length of the melt compression zone is preferably about 1 / 10 to 3 / 10 of the length L in the extrusion direction of the barrel 10, and the length of the metering zone is preferably about 1 / 10 to 3 / 10 of the length L in the extrusion direction of the barrel 10.

[0035] The injection molding device 1, 1' can be any one of a screw type, a vibration type, a belt type, a table type, and a rotary type. The screw speed of the screw type injection molding device can be, for example, 20 to 500 rpm. It should be noted that the screw speed is preferably 20 to 300 rpm, more preferably 70 to 300 rpm, further preferably 80 to 250 rpm, and most preferably 150 to 250 rpm.

[0036] When heated by the heater 14 in the barrel 10, the plasticizing time of the powder 50 can preferably be set to 10 to 60 seconds, more preferably 10 to 40 seconds, and further preferably 10 to 30 seconds. It should be noted that although the plasticizing time in each of the embodiments described below is set to 13 to 26 seconds, it takes up to 40 seconds to prepare conventional molded products, especially large molded products (thickness 4 to 7 mm). For example, in the case of thickened molded products for glass (for example, a thickness of about 5 mm), the metering time requires about 40 seconds. In conventional headlamp molded products, the plasticizing time of the powder 50 is 15 to 30 seconds, and the cooling time of the molded product is 25 to 40 seconds, so the molding cycle is 50 to 70 seconds.

[0037] The temperature in the cylinder 10 can be set to 230 to 360° C. The temperature in the cylinder 10 is preferably 230 to 350° C., more preferably 260 to 340° C., and further preferably 280 to 330° C. (corresponding to the examples) on the hopper 32 side (the hungry feeding device 30 side).

[0038] The temperature in the barrel 10 can be preferably set to 230 to 360° C. at the front end temperature (discharging nozzle 40 side), more preferably 270 to 350° C., and further preferably 290 to 340° C. (corresponding to the embodiment). It should be noted that, considering the use of a magnetic disk grade represented by Iupilon H4000 as a powder or granular material, the lower limit of the temperature range must include a case where the temperature is lower than the temperature (230° C.) of the embodiment.

[0039] [Manufacturing method] The following is a method for manufacturing a polycarbonate resin molded article. When a polycarbonate resin is molded by an injection molding device 1 to manufacture a polycarbonate resin molded article, the method includes a step of feeding a powder or granule 50 of the polycarbonate resin into a barrel 10 in a hungry state by a powder or granule quantitative feeding device 30; a step of plasticizing the powder or granule 50 by rotating the screw 20 in the barrel 10 heated by the heater 14 to generate a plasticized resin; and a step of extruding the plasticized resin from a discharge nozzle 40 by rotating the screw 20 to form a molded article.

[0040] [Powder and granular material] The manufacturing method of this embodiment can use polycarbonate resin powder. The powder 50 is preferably, but not limited to, a crumb or granular product. The specific surface area of ​​the powder 50 is preferably 0.01 m 2 / g or more. Preferably, 50% by weight or more of the powder or granule 50 has a particle size in the range of 200 to 2000 μm, more preferably 200 to 1500 μm, and even more preferably 200 to 1200 μm. It should be noted that the particle morphology of the powder or granule 50 can be measured according to the method described in JIS K0069 (sieve test method).

[0041] The powder 50 may have a predetermined water content (water absorption rate). The predetermined water content of the powder 50 may preferably be set to 0.3% by mass or less, and more preferably 0.2% by mass or less. The water content of the powder 50 may preferably be set to 0.01% by mass or more, more preferably 0.06% by mass or more, and further preferably 0.065% by mass or more. The water content range of the powder 50 may preferably be set to 0.06% by mass (600ppm) to 0.3% by mass (3000ppm), more preferably 0.065% by mass (650ppm) to 0.2% by mass (2000ppm), and further preferably 0.065% by mass (650ppm) to 0.17% by mass (1700ppm). Since the powder 50 has a predetermined water content and a water content range, the color tone of the molded body is improved, the generation of bubbles (silver streaks) can be prevented, and the color tone is further improved.

[0042] In the existing method for manufacturing polycarbonate resin molded products, the raw materials are dried before molding for the purpose of removing moisture (to prevent silver streaks, that is, to prevent bubbles from being generated in the molded body). In the present invention, unexpectedly, when the powder and granules are fed to the injection molding device in a hungry state with a specified moisture content (the powder and granules are not dried), a molded body with excellent YI value (color tone) is obtained. This fact can be understood by comparing Examples 1 to 8 with Examples 9 and 10. In the manufacturing method of the present invention, since the drying process of the powder and granules is omitted, the molding process can be simplified and the burden of quality assurance management can be reduced.

[0043] Injection molding can be performed by supplying a polycarbonate resin powder 50 having a water content of 0.3 mass % or less to the injection molding apparatus 1, 1'. When the water content of the powder 50 is 0.3 mass % or less, when injection molding is performed using, for example, an injection molding apparatus 1' provided with a vent, volatile components can be stably discharged from the vent 12, thereby making it easy to obtain a molded product with stable quality.

[0044] From the perspective of emission efficiency of volatile components, the moisture content of the powder 50 is preferably low to a certain extent. For example, the moisture content is preferably 0.2 mass % or less, more preferably 0.1 mass % or less. In addition, from the perspective of metering stability of the powder 50, such a moisture content is also preferred.

[0045] The powder 50 used in the present invention may be dried before being supplied to the injection molding apparatus 1, 1' or may be used directly without drying. However, according to the examples, it is preferably used directly without drying because a molded body with a small YI value can be obtained.

[0046] It should be noted that the polycarbonate resin obtained by the interfacial method is a product obtained in the form of crumbs (powder particles) due to its manufacturing process, and the obtained crumbs are further pelletized. Usually, the pellets of the polycarbonate resin are molded into molded products. In contrast, the present invention has the advantage of being able to omit the pelletization process.

[0047] [Hungry feeding] In the manufacturing method of the present invention, the powder and granules of the polycarbonate resin are fed to the injection molding device 1, 1' in a hungry state. Usually, when the polycarbonate resin as a raw material is not fed in a hungry state, it is fed by the hopper 32 equipped with the feed port 10a at the rear end side of the barrel 10 of the injection molding device 1, 1' by the weight of the raw material. In this case, the part from the hopper 32 through the feed port 10a of the injection barrel to the screw 20 is filled with the powder and granules 50.

[0048] In contrast, when the material is fed to the injection molding device 1, 1' in a hungry state, Figure 2 As shown, the feeder 30 feeds a set amount of the polycarbonate resin powder or granule 50 into the feed port 10 a of the barrel 1 while adjusting the supply amount of the polycarbonate resin powder or granule 50 from the hopper 32 using the screw feeder 34 .

[0049] By controlling the input amount of the polycarbonate resin powder 50, the screw groove of the screw 20 directly below the feed port 10a is not covered by the powder 50 but is partially exposed. By supplying the powder 50 in this state, hungry feeding is performed.

[0050] When the raw material (powder and granular material) is fed in a starved state, a gap (void) without raw material is formed in the feed port 10a of the barrel 10, and gas components generated in the injection barrel 10 are discharged from the gap to the outside of the system. That is, the inventors believe that since the feed port 10a plays the same function as a vent, the discharge efficiency of volatile components and water vapor is improved, and a molded product with excellent color tone (YI) and few bubbles is obtained.

[0051] A commercially available product may be used as a hungry feeding device for performing such hungry feeding, for example, "Hungry Feeder HF-1" manufactured by Nippon Oil Corporation used in the examples described below.

[0052] The rotation speed of the screw feeder 34 for performing starved feeding of powder or granule is preferably 20 to 500 rpm, more preferably 70 to 300 rpm, 80 to 250 rpm, or 150 to 250 rpm.

[0053] The advantages of starvation feeding are as follows.

[0054] 1. The retention time of the powder 30 and the plasticized resin in the barrel 10 is shortened, thereby suppressing the change in color tone and the decrease in molecular weight of the molded product.

[0055] 2. When the injection molding device 1' is used, the volatile gas is discharged to the outside of the system through the vent 12, and silver streaks are less likely to appear.

[0056] 3. The state of the powder and granule 50 from plasticization to melting is stable, surging is not likely to occur, and uniform plasticization can be achieved.

[0057] 4. The melting start position is closer to the front end of the barrel 10, which is convenient for material replacement and reduces the amount of cleaning agent used.

[0058] 5. The wear of the screw 20 is suppressed.

[0059] 6. The rotational torque of the screw 20 is reduced, and energy consumption is reduced.

[0060] The hungry feeding device 30 is not particularly limited, as long as it can supply powder, and can be a screw feeder, a vibrating feeder, a belt feeder, a rotary feeder, a table feeder, etc. The screw feeder 34 illustrated in the embodiment is preferred because it is easy to precisely mold. In addition, during the hungry feeding, the rotation speed of the screw feeder 34 of the hungry feeding device 30 changes according to the size of the screw and the shape of the tooth groove. Therefore, although it is not necessary to set it according to the rotation speed of the screw 20 of the injection molding device 1, 1', the following relationship still exists. The following embodiment conforms to the relationship 1.

[0061] The speed of the feeding device is ≥ the speed of the extrusion molding device (relationship 1) In equation 1, the rotation speed of the feeding device is the rotation speed of the screw feeder 34, and the rotation speed of the extrusion molding device is the rotation speed of the screw 20. It should be noted that if the screw feeder 34 of the feeding device 30 is larger than the screw 20 of the extrusion molding device, equation 1 does not hold.

[0062] As a limit on the feed amount during the hungry feeding process, the feed rate can be sufficient to complete metering (plasticization) within the required cooling time. If it is longer than this time, additional metering time (plasticization time) will be required after cooling, resulting in the problem of unnecessary extension of the molding cycle. In order to solve this problem, it is preferred to operate according to the relationship in the above relationship 1.

[0063] [Ventilation vent] Generally, when pellets are fed from the hopper 32 instead of powders, the provision of vents tends to make the YI value smaller (better color tone). However, in the embodiment described later, when feeding powders (crumbs) in a hungry state, a molded product with a low YI value (good color tone) is obtained without vents. The inventor believes that the reason is that when there are vents 12, the screw 20 has a kneading section (Dulmadge, alveolar section), so coloring occurs due to shear heat release. That is, the manufacturing method according to the present invention has the advantage of being able to obtain a molded product with good color tone even without vents.

[0064] The vent 12 needs to be considered to avoid the burden on the operation of the extruder 1' caused by vent-up (the vent is blocked by resin) and foreign matter mixed in from the vent during the operation of the molding device. Even in the case where the vent 12 is not provided as in the extrusion molding device 1, the YI value of the molded product can be reduced (color tone is improved). Therefore, by reducing the operating load, the productivity of the molded body is improved. In addition, when the vent 12 is not provided, the melt compression zone can be omitted.

[0065] In addition, when equipped with vents, high equipment costs will be incurred in practice. And because of the need for fine vent management, the molding process is complicated and its management requires a lot of labor. For example, in the case of cleaning the resin and volatiles adhering to the vents or the unfortunate occurrence of material overflow, it will take a lot of energy and time to restore the original state. In addition, when changing the type of resin, there will be problems such as the resin replacement in the screw 20 takes a long time or consumes a lot of replacement resin.

[0066] Therefore, compared with the scheme of equipping a vent to prevent the generation of color tone and bubbles, the scheme of feeding the powder and granules (crumbs) in a hungry state can obtain a molded body with a low YI value (high quality). Example 11 is a case where a vent is provided. It can be seen that in the case of Example 2 without a vent, the color tone is improved. Except for whether there is a vent, Example 11 is the same as Example 2. It should be noted that even in the case of Example 11, a molded body with a reduced YI value can be obtained.

[0067] [Injection molding conditions] In the present invention, as described above, the injection molding conditions can be conventional conditions except that the polycarbonate resin in the form of powder (crumbs) with a moisture content of 0.3% or less is fed in a hungry state using an injection molding device. The barrel temperature of the injection molding device 1, 1' is appropriately adjusted according to the melting temperature and melt viscosity of the resin (powder) used. For example, it is preferably implemented under the conditions of the barrel temperature of the injection molding device 1, 1' being 230 to 360°C and the mold temperature being 60 to 120°C.

[0068] [summary] Conventional polycarbonate resin molded products still have the problem of bubbles (silver streaks) in the molded body. In order to ensure operability during molding and accurate supply to the molding device, it is known that polycarbonate resin in powder (crumb) form is usually processed into pellets, and the pellets that have undergone a drying process are molded.

[0069] In contrast, the manufacturing method of the present invention provides a manufacturing method in which a powder or granular body of a polycarbonate resin is fed in a hungry state to a feed port of an injection molding device under a state of having a specified moisture content. Thus, a molded product with fewer bubbles and a low YI value can be obtained. Moreover, by omitting the above-mentioned drying step, a molded product with an even lower YI value can be obtained. It should be noted that the manufacturing method of the present invention, when using a powder or granular body of a polycarbonate resin, can reduce the YI value to a greater extent and more effectively than when using a pellet of a polycarbonate resin.

[0070] Example The following describes the embodiments and comparative examples of the present invention. The extrusion molding devices 1 and 1' used "NEX-50-4-5EG" manufactured by Nissei Plastic Industry Co., Ltd. The hungry feeder 30 used "Hungry Feeder HF-1" manufactured by Nippon Oil Machinery Co., Ltd. The powder and granular body 50 (chips) used "Iupilon (registered trademark) E-2000F" manufactured by Mitsubishi Engineering-Plastics Corporation.

[0071] The metering time (plasticizing time) is measured by the measuring unit of the injection molding device 1, 1' to measure the rotation time of the screw 20 of the injection molding device 1, 1', and it is displayed on the display unit as the metering time. The YI value is formed into a test piece of a molded body of 50×80×3mm, and the color tone of 3mm thickness is measured with a colorimeter. The colorimeter used is "SE6000" manufactured by Nippon Denshoku Industries Co., Ltd. The bubbles in the molded product were judged by the naked eye on the appearance of the test piece (50×80×3mm) used for the above-mentioned YI value measurement. The test piece with silver streaks was judged as "with bubbles", and the one without silver streaks was judged as "without bubbles".

[0072] (Example 1) As the powder (crushed material), Iupilon (registered trademark) E-2000 crushed material was used. Figure 1 The hopper shown was equipped with a hungry feeder 30 (Hungry Feeder HF-1) and an injection molding device 1 (NEX-50-4-5EG), and injection molding was performed under the operating conditions shown in Table 1 with hungry feeding. The screw of the injection molding device has an L / D ratio of 20 and a screw diameter of 26 mm, which is a low compression type screw. The molding conditions and physical properties of the obtained molded product are shown in Table 1.

[0073] (Examples 2 to 8) Injection molding was performed in the same manner as in Example 1 except that the operating conditions were changed to those shown in Table 1. Table 1 shows the molding conditions and physical properties of the obtained molded article.

[0074] (Examples 9 and 10) The powder (Iupilon (registered trademark) E-2000 chips) was dried in a hot air dryer at 120°C for 2 hours. Injection molding was performed in the same manner as in Example 1 except that the powder was used and the operating conditions shown in Table 1 were used. The molding conditions and physical properties of the obtained molded article are shown in Table 1.

[0075] (Example 11) Injection molding was performed in the same manner as in Example 2 except that vents and a melt compression zone were provided in the screw. Table 1 shows the molding conditions and physical properties of the obtained molded article.

[0076] (Comparative Examples 1 to 4) Injection molding was performed in the same manner as in Example 1 except that the hungry feeder (HF-1) was not installed and the operating conditions were changed to those shown in Table 1. Table 2 shows the molding conditions and physical properties of the obtained molded article.

[0077] (Comparative Examples 5 to 9) Injection molding was performed in the same manner as in Example 1, except that pellets ("Iupilon (registered trademark) E-2000 pellets" manufactured by Mitsubishi Engineering-Plastics Corporation) were used as the polycarbonate resin raw material instead of the powder (Iupilon (registered trademark) E-2000 chips), and the operating conditions were changed to those shown in Table 1. The molding conditions and physical properties of the obtained molded article are shown in Table 2.

[0078] The results confirmed that, in the case of pellet molding, the scheme that was dried before molding could obtain a molded body with good color tone and no bubbles (Comparative Examples 5 and 6), but in the case of feeding the crumbs in a hungry state, the scheme that was not dried improved the color tone (based on the results of Examples 1 to 8, Examples 9 and 10). Therefore, Examples 1 to 8 and 11 not only did not require a drying process, reduced energy consumption, and saved labor, but also obtained a molded body with good color tone.

[0079] In the embodiment, the hungry feeder 30 (Hungry Feeder HF-1) mainly supplies powder and granules while sucking water vapor, heptane and dichloromethane used in the polycarbonate resin production process by the interface method from the suction port. The suction port is structured to be able to reduce the pressure to a certain extent by a vacuum filter so that the gas in the system can be discharged smoothly.

[0080] [Table 1] [Table 2] (Summary of the embodiments) Examples 1 to 4 are cases where undried crumbs are fed in a hungry state, and Example 9 is a case where dried crumbs are fed in a hungry state. Compared with Example 9, the YI value of Examples 1 to 4 is reduced by about 22%. Examples 5 to 8 are cases where undried crumbs are fed in a hungry state, and Example 10 is a case where dried crumbs are fed in a hungry state. Compared with Example 10, the YI value of Examples 5 to 8 is reduced by about 16 to 18%. Examples 1 to 8 obtained high-quality molded products without bubbles. In addition, Examples 1 to 8 had lower YI values ​​than Comparative Examples 7 and 8, where undried pellets were fed in a hungry state. Since the YI values ​​of Examples 1 to 11 were all very low and no bubbles were generated in the molded products, ideal molded products were obtained.

[0081] Comparative Examples 1 to 4 are cases where undried crumbs were fed in a non-starved state, and bubbles were generated in the molded products, so ideal molded products could not be obtained. Comparative Examples 5 to 10 are cases where pellets were used, and the YI values ​​were higher than those of Examples 1 to 11, so ideal molded products could not be obtained.

[0082] Explanation of symbols 1: Injection molding device 1': Injection molding device with vents 10: Barrel 12: Ventilation 14: Heater 20: Screw 30: Hungry Feeding Device 32: Hopper 34: Screw feeder 40: Spit out your mouth 50: Powder

Claims

1. A method for producing a molded article of a polycarbonate resin, wherein the polycarbonate resin is molded using an injection molding device, wherein: include: The step of feeding the polycarbonate resin powder and granules into the injection molding device in a hungry state; The step of plasticizing the powder and granules in the injection molding device to produce a plasticized resin; and a step of molding the plasticized resin into the molded product, The water content of the powder or granule supplied to the injection molding device in the starved feed is 0.3 wt % or less.

2. The method according to claim 1, characterized in that More than 50% by weight of the powder or granule supplied in the starved state feed has a particle morphology of 200 to 2000 μm.

3. The method according to claim 2, characterized in that The specific surface area of ​​the powder and granules supplied in the starved state is 0.01 m 2 / g or above.

4. The method according to claim 1, characterized in that The powder or granule supplied in the hungry state feed is a powder or granule in the form of crumbs or fine particles.

5. The method according to claim 1, characterized in that The moisture content of the powder or granule supplied in the starved state feed is 0.01 wt % or more.

6. The method according to claim 5, characterized in that The moisture content of the powder or granule supplied in the starved state feed is 0.06 wt % or more.

7. The method according to claim 1, characterized in that The moisture content of the powder or granule supplied in the starved state feed is 0.20 wt % or less.

8. The method according to claim 1, characterized in that The moisture content of the powder or granule supplied in the starved state feed is 0.01 wt % or more and 0.20 wt % or less.

9. The method according to claim 1, characterized in that The specific surface area of ​​the powder and granules supplied in the starved state is 0.01 m 2 / g or more, and 50 weight % or more of the powder or granule supplied in the starved state feed has a particle size of 200 to 2000 μm.

10. The method according to claim 1, characterized in that The hungry feeder in the injection molding device is any one of a screw type, a vibration type, a belt type, a table type and a rotary type.

11. The method according to claim 10, characterized in that The screw speed of the screw-type hungry feeder in the injection molding device is 20 to 500 rpm.

12. The method according to claim 1, characterized in that In the step of plasticizing the powder or granule, the powder or granule is plasticized for 10 to 60 seconds.

13. The method according to claim 1, characterized in that The injection molding device has a barrel, and the temperature inside the barrel is 230 to 360°C.

14. The method according to claim 13, characterized in that A screw is arranged in the barrel, and the rotation speed of the screw is 10 to 200 rpm.

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