Method and manufacturing system for producing molded products

Abstract

To provide a method and manufacturing system for producing molded articles that are environmentally friendly and capable of producing molded articles with high heat resistance and strength. [Solution] A method for producing a molded article comprising: a first step of forming a material containing a cellulose derivative into a molded article; and a second step of performing a treatment on the molded article produced in the first step, maintaining it at a predetermined temperature range for a predetermined time t, wherein when the phase transition point of the molded article is A (°C), the temperature range in the second step is A-10°C or higher and A+50°C or lower.

Description

Technical Field

[0001] The present invention relates to a method and a manufacturing system for producing molded articles. Background Art

[0002] Cellulose derivatives are renewable resources excellent in biocompatibility and degradability, and are environmentally friendly materials, and thus have attracted much attention in recent years. In addition, a technology for obtaining a molded body by injection molding a raw material containing a cellulose derivative has attracted particular attention (see, for example, Patent Document 1). Prior Art Literature Patent Literature

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. 2018-059125 Summary of the Invention Problems to be Solved by the Invention

[0004] However, although molded articles obtained by injection molding a raw material containing a cellulose derivative are environmentally friendly, they have the problem of insufficient heat resistance and strength. Means for Solving the Problems

[0005] A method for producing a molded article according to an application example of the present invention comprises: a first step of molding a material containing a cellulose derivative into a molded body; a second step of producing a molded article by subjecting the molded body produced in the first step to a treatment of maintaining the molded body within a predetermined temperature range for a predetermined time t, when the phase transition point of the molded body is A (° C), the temperature range in the second step is not less than A-10° C and not more than A+50° C.

[0006] A manufacturing system according to an application example of the present invention comprises: a molding machine that molds a material containing a cellulose derivative into a molded body; A warming cabinet that performs a process on the molded body formed by the molding section, maintaining it at a predetermined temperature range for a predetermined time t, The system includes a conveyor that transports the molded body from the molding section to the warming cabinet, When the phase transition point of the molded article is A (°C), the temperature range is A -10°C or higher and A +50°C or lower. [Brief explanation of the drawing]

[0007] [Figure 1] Figure 1 is a schematic diagram showing a manufacturing system for carrying out a method for producing molded articles according to an embodiment of the present invention. [Figure 2] Figure 2 is a graph showing the change in heat absorption of the molded body over time in the second step. [Figure 3] Figure 3 is a flowchart illustrating an example of a method for producing the molded article of the present invention. [Figure 4] Figure 4 is a table summarizing the manufacturing conditions and evaluation results for each example and comparative example. [Modes for carrying out the invention]

[0008] The method and manufacturing system for producing the molded articles of the present invention will be described in detail below based on preferred embodiments shown in the accompanying drawings.

[0009] <Embodiment> Figure 1 is a schematic diagram showing a manufacturing system for carrying out a method for producing a molded article according to an embodiment of the present invention. Figure 2 is a graph showing the change in heat absorption of the molded article over time in the second step. Figure 3 is a flowchart illustrating an example of a method for producing a molded article according to the present invention. Figure 4 is a table summarizing the manufacturing conditions and evaluation results for each example and comparative example.

[0010] [Manufacturing systems, methods for producing molded products] As shown in Figure 1, the manufacturing system 1 is an apparatus that performs an example of a method for producing molded products of the present invention, and comprises a molding unit 2 (molding machine), a conveying unit 3 (conveyor), a warming cabinet 4, and a control unit (not shown). The molding unit 2, the conveying unit 3, and the warming cabinet 4 are controlled by the control unit (not shown). The manufacturing system 1 sequentially performs a molding process (first step), a conveying process, and a processing process (second step).

[0011] Furthermore, the present invention may be applied to a manufacturing system in which the molding unit 2, the conveying unit 3, the warming cabinet 4, and the control unit (not shown) are all separate devices and are connected to form a single system. Alternatively, the present invention may be applied to a molded product manufacturing system that does not have the conveying unit 3 and the warming cabinet 4, but consists only of the molding unit 2 and the control unit. The following provides a detailed explanation of each part and process.

[0012] [1] Molding department, molding process As shown in Figure 1, the molding unit 2 is the part that produces a molded body M2 (molded product M3) by injection molding a material M1 containing a cellulose derivative. The molding unit 2 may be a well-known injection molding machine. The molding unit 2 has an injection unit 21 and a mold clamping unit 22. The material M1 will be described in detail later.

[0013] [1-1] Configuration of the molded section The injection unit 21 includes a hopper 211 and a cylinder 212. The hopper 211 is the part that supplies material M1 to the cylinder 212. The form of material M1 supplied to the cylinder 212 is not particularly limited, but examples include powder, cotton, etc.

[0014] The cylinder 212 includes an outer cylinder 213 to which a hopper 211 is connected, a screw 214 that rotates inside the outer cylinder 213, a motor 215 that rotates the screw 214, and a heater 216 that heats the inside of the outer cylinder 213. The motor 215 and the heater 216 are electrically connected to a control unit (not shown) and their operation is controlled.

[0015] The material M1 supplied into the cylinder 212 via the hopper 211 is plasticized by heating from the heater 216. The plasticized material M1 is extruded from the opening 217 of the outer cylinder 213 by the rotation of the screw 214.

[0016] The mold clamping unit 22 includes a fixed mold 221 and a movable mold 222. When the fixed mold 221 and the movable mold 222 are assembled, a cavity 223 is formed therebetween. The plasticized material M1 flows into the cavity 223. The flowed material M1 is pressurized between the fixed mold 221 and the movable mold 222 and cooled. Thereby, the material M1 in the cavity 223 is cured, and a molded body M2 (primary molded body) is manufactured.

[0017] The fixed mold 221 and the movable mold 222 may be configured to have flow paths inside. In this case, cooling can be performed by causing a refrigerant to flow down through the flow paths.

[0018] When taking out the molded body M2 from the cavity 223, the movable mold 222 is separated from the fixed mold 221. The method for separating the movable mold 222 from the fixed mold 221 is not particularly limited, and examples thereof include a method manually performed by an operator, and a method in which a movement mechanism (not shown) is connected to the movable mold 222 and the operation thereof is controlled by a control unit.

[0019] The temperature of the plasticized material M1, that is, the temperature of the material M1 when supplied from the injection unit 21 to the mold clamping unit 22, is not particularly limited, but is set to be higher than the phase transition point (the temperature at which the morphology changes). For example, the temperature is preferably 180°C or higher and 350°C or lower, and more preferably 200°C or higher and 340°C or lower. Thereby, the material M1 can be plasticized more effectively, and the supply of the material M1 into the cavity 223 can be performed more favorably and smoothly.

[0020] The cooling temperature of the molded body M2, that is, the temperature at which the molded body M2 is removed from the clamping unit 22, is not particularly limited, but should be lower than the phase transition temperature. For example, it is preferably 50°C to 250°C, and more preferably 70°C to 200°C. This makes it possible to more effectively increase the heat resistance and strength of the molded body M2.

[0021] Cooling of the molded body M2 may be omitted. That is, after molding the molded body M2, the mold clamping unit 22 may be immediately transported to the warming cabinet 4 while the molded body M2 is still inside the clamping unit 22 to perform the processing step.

[0022] [1-2]Material M1 Material M1 contains a cellulose derivative. Cellulose derivatives are compounds that can be derived from cellulose through chemical reactions. Cellulose derivatives are lightweight, possess excellent strength, are highly biocompatible, easily degradable, and are environmentally friendly.

[0023] Examples of cellulose derivatives include cellulose ethers, cellulose esters, and alkali metal salts such as sodium and potassium, as well as ammonium salts thereof. Among these, cellulose esters are preferred.

[0024] Examples of cellulose ethers include carboxymethylcellulose, carboxyethylcellulose, carboxymethylethylcellulose, and their sodium and potassium salts, hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, methylcellulose, ethylcellulose, methoxymethylcellulose, benzylcellulose, and one or more selected from mixtures and copolymers thereof.

[0025] Examples of cellulose esters include organic acid esters such as cellulose acetate, cellulose propionate, and cellulose butyrate; mixed esters such as cellulose acetate propionate and cellulose acetate butyrate; grafts such as polycaprolactone-grafted cellulose acetate; and inorganic acid esters such as cellulose nitrate, cellulose sulfate, and cellulose phosphate.

[0026] Cellulose esters with an acyl substitution degree of 2.7 or less are also called incompletely substituted cellulose esters. It is preferable to use incompletely substituted cellulose esters as material M1 rather than cellulose esters with an acyl substitution degree greater than 2.7. This makes it possible to further effectively improve the heat resistance and strength of the molded article M2 after the processing steps described later.

[0027] The degree of polymerization (viscosity-average degree of polymerization) of the cellulose ester is not particularly limited, but is preferably 200 to 400, and more preferably 210 to 390. This makes it possible to more effectively increase the heat resistance and strength of the molded article M2 after going through the processing steps described later.

[0028] Furthermore, the average molecular weight of the cellulose derivative is preferably between 1,000 and 1,000,000, and more preferably between 5,000 and 100,000. This allows for a more effective improvement in the heat resistance and strength of the molded product M3 after the processing steps described later.

[0029] The average molecular weight can be measured by GPC (gel permeation chromatography) using polyethylene oxide as the standard.

[0030] The content of cellulose derivatives in material M1 is not particularly limited, but is preferably 80% to 100% by mass, and more preferably 90% to 99% by mass. This ensures a sufficient content of cellulose derivatives.

[0031] Material M1 may contain other components in addition to the cellulose derivative, such as unsubstituted cellulose (unreacted cellulose), plasticizers, flame retardants, etc.

[0032] The content of other components in material M1 is not particularly limited, but is preferably 0% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less. This ensures a sufficient content of cellulose derivatives.

[0033] [1-3] Molded body M2 The shape of the molded body M2 is not particularly limited. The molded body M2 referred to in this application is obtained by melting and molding material M1.

[0034] [2] Conveying section, conveying process As shown in Figure 1, the transport unit 3 has the function of transporting the molded body M2 removed from the clamping unit 22 to the warming cabinet 4. The transport unit 3 can be a robot with a hand, a configuration with a transport belt, or a combination of these. Alternatively, the clamping unit 22 may be removed from the injection unit 21 together with the molded body M2, and the clamping unit 22 containing the molded body M2 may be transported. The transport unit 3 is electrically connected to a control unit (not shown) and its operation is controlled. During this transport, the molded body M2 may cool to room temperature, or it may be transported while being kept at a temperature above that maintained in the warming cabinet 4.

[0035] Note that the transport unit 3 may be omitted. For example, an operator may manually remove the molded body M2 from the clamping unit 22 and transport it to the warming cabinet 4, where the molded body M2 will be placed into the chamber 41, which will be described later. Alternatively, the processing steps described later may be performed within the clamping unit 22 attached to the injection unit 21.

[0036] [3] Insulated cabinet, processing steps As shown in Figure 1, the warming cabinet 4 is the part that performs a processing step (second step) in which the molded body M2 formed by the molding unit 2 is maintained at a temperature T (°C) for a time t (seconds). This allows a molded product M3 (secondary molded body) to be obtained.

[0037] Furthermore, it is not necessary to change the temperature during the processing step, or, as will be described later, the temperature may be changed during the processing step.

[0038] The warming cabinet 4 comprises a chamber 41 and a heater 42. The chamber 41 has a door 411, and the molded body M2 is loaded and unloaded by opening the door 411. The heater 42 is installed inside the chamber 41 and has the function of heating the inside of the chamber 41. The heater 42 is electrically connected to a control unit (not shown) and its operation is controlled.

[0039] The temperature during the process performed by the insulated cabinet 4, specifically temperature T(°C) (first temperature T1(°C)), is set to be between A-10°C and A+50°C, where A(°C) is the phase transition point Tg of the molded body M2. This improves the heat resistance and strength (impact resistance) of the molded product M3. In other words, by going through the process in the insulated cabinet 4, it is possible to obtain a molded product M3 of a cellulose derivative that is environmentally friendly and has high heat resistance and strength.

[0040] More specifically, in the case of a molded article M2 with a phase transition temperature Tg of 110°C, the temperature T(°C) (first temperature T1(°C)) is preferably between 100°C and 160°C. This makes it possible to obtain a molded article M3 of a cellulose derivative with excellent heat resistance and strength.

[0041] The processing time for the molded body M2, that is, the time t (seconds) for maintaining it at the first temperature T1 (°C), is preferably such that the processing time exceeds the endothermic peak of the molded body M2. Exceeding the endothermic peak of the molded body M2 indicates that the deformation of the molded body M2 has been accelerated, and therefore, the heat resistance and strength of the molded product M3 can be more effectively increased during this process.

[0042] Time t (seconds) (first time t1 (seconds)) may be defined as the length of time during the processing step at which the heat absorption of the molded body M2 becomes 0.0001 W / g or less, or at least 0.00005 W / g or less. In this processing, the heat resistance and strength of the molded product M3 can be more effectively improved.

[0043] Figure 2 is a graph showing the change in endothermic activity over time for a molded body M2 with a phase transition temperature (Tg) of 110°C. In the graph shown in Figure 2, the horizontal axis represents time, and the vertical axis represents the amount of heat absorbed (W / g).

[0044] When the temperature T(°C) (first temperature T1(°C)) is 100°C, the endothermic peak occurs at approximately 400 seconds (time t(seconds)), and the amount of heat absorbed becomes almost zero at approximately 600 seconds (time t1(seconds)).

[0045] When the temperature T(°C) (first temperature T1(°C)) is 110°C, the endothermic peak occurs at approximately 400 seconds (time t(seconds)), and the amount of heat absorbed becomes almost zero at approximately 600 seconds (time t1(seconds)).

[0046] When the temperature T(°C) (first temperature T1(°C)) is 120°C, the endothermic peak occurs at a time t(seconds) of about 200 seconds, and the amount of heat absorbed becomes almost zero at a time t(seconds) (time t1(seconds)) of about 500 seconds.

[0047] When the temperature T(°C) (first temperature T1(°C)) is 130°C, the endothermic peak occurs at a time t(seconds) of approximately 1000 seconds, and the amount of heat absorbed becomes almost zero at a time t(seconds) (time t1(seconds)) of approximately 2800 seconds.

[0048] When the temperature T(°C) (first temperature T1(°C)) is 140°C, the endothermic peak occurs at approximately 1200 seconds (time t(seconds)), and the amount of heat absorbed becomes almost zero at approximately 1900 seconds (time t1(seconds)).

[0049] When the temperature T(°C) (first temperature T1(°C)) is 150°C, the endothermic peak occurs at a time t(seconds) of approximately 700 seconds, and the amount of heat absorbed becomes almost zero at a time t(seconds) (time t1(seconds)) of approximately 1500 seconds.

[0050] When the temperature T(°C) (first temperature T1(°C)) is 160°C, the endothermic peak occurs at a time t(seconds) of approximately 1000 seconds, and the amount of heat absorbed becomes almost zero at a time t(seconds) of approximately 2100 seconds.

[0051] When the temperature T(°C) (first temperature T1(°C)) is 170°C, the endothermic peak occurs at a time t(seconds) of about 200 seconds, and the amount of heat absorbed becomes almost zero at a time t(seconds) (time t1(seconds)) of about 1000 seconds.

[0052] When the temperature T(°C) (first temperature T1(°C)) is 180°C, the endothermic peak occurs at approximately 300 seconds (time t(seconds)), and the amount of heat absorbed becomes almost zero at approximately 400 seconds (time t1(seconds)).

[0053] The change in heat absorption over time, as described above, can be measured using differential scanning calorimetry (DSC).

[0054] Therefore, the time t (seconds) can be set according to the temperature T (°C). For example, it may be set to 150 seconds or more and 3500 seconds or less, or to 270 seconds or more and 1200 seconds or less. This allows the processing of the molded body M2 by the warming cabinet 4 to be carried out more effectively, and the heat resistance and strength of the molded product M3 can be improved more effectively.

[0055] Furthermore, the internal temperature of the warming cabinet 4 is not limited to being kept constant at a temperature T (°C) for a period of time t (seconds). The internal temperature of the warming cabinet 4 may be varied within the range of A-10°C to A+50°C, or it may be varied intermittently so that it moves outside the range of A-10°C to A+50°C before entering the range of A-10°C to A+50°C. If the internal temperature of the warming cabinet 4 is varied intermittently, the cumulative time spent within the range of A-10°C to A+50°C should equal time t (seconds).

[0056] [4] Molded product M3 The molded product M3, as defined in this application, is obtained by treating the molded body M2 to enhance its heat resistance and strength. Furthermore, the final product obtained after post-processing and assembly following the treatment of the molded body M2 is also referred to as the molded product M3 in this application.

[0057] [5] Control Unit The control unit, although not shown in the figure, includes a processor, memory, communication unit, etc. The processor may include a CPU, accelerator, etc. The control unit controls the operation of each of the above-mentioned parts to execute a method for producing molded products. The following explanation will be given with reference to Figure 3. The control unit controls the operation of the warming cabinet 4 and maintains the temperature at T (°C) (first temperature T1 (°C)). Then, the control unit controls the operation of the molding unit 2 to inject-molded the material M1 (step S1). Next, the control unit controls the operation of the molding unit 2 and the transport unit 3 to transfer the generated molded body M2 from the molding unit 2 to the transport unit 3 (step S2). Then, the control unit opens the door 411 of the warming cabinet 4 (step S3). Next, the control unit controls the operation of the transport unit 3 to put the molded body M2 into the warming cabinet 4 through the opened door 411 (step S4). After that, the control unit closes the door 411 of the warming cabinet 4 (step S5). The control unit waits for a time t (seconds) to elapse after the molded body M2 enters the warming cabinet 4. Once time t (seconds) has elapsed (step S6: YES), the process proceeds to step S7. The control unit then causes the door 411 of the warming cabinet 4 to open (step S7). The control unit controls the operation of the transport unit 3 to remove the molded product M3 from the warming cabinet 4 through the opened door 411 (step S8). After that, the control unit causes the door 411 of the warming cabinet 4 to close (step S9). Next, the control unit controls the operation of the transport unit 3 to transport the removed molded product M3 to the finished product storage area and place it there (step S10). In step S10, the control unit may, if necessary, control the process to perform post-processing or assembly of the removed molded body M2, and then place the post-processed molded product M3 or assembled molded product M3 in the finished product storage area.

[0058] [6] Summary of this embodiment As explained above, the method for producing a molded product comprises a first step of molding a material M1 containing a cellulose derivative into a molded body M2, and a second step of producing a molded product M3 by maintaining the molded body M2 produced in the first step at a first temperature T1 (°C) for a time t (seconds). When the phase transition point Tg of the molded body M2 is A (°C), the first temperature T1 (°C) in the second step is between A-10°C and A+50°C. This makes it possible to obtain a molded product M3 that exhibits excellent heat resistance and strength. In other words, by going through the treatment in the insulated cabinet 4, it is possible to obtain a molded product M3 that is environmentally friendly and has high heat resistance and strength.

[0059] In this embodiment, the case in which the second step is performed in the warming cabinet 4 has been described, but the present invention is not limited to this, and the second step may be performed anywhere. For example, the warming cabinet 4 may be omitted, and the second step may be performed while the injection-molded product is still in its original state. That is, the second step may be performed in the clamping unit 22.

[0060] The time t is preferably the length of time during the second step when the endothermic peak of the molded body M2 is exceeded. This makes it possible to more effectively increase the heat resistance and strength of the molded body M2.

[0061] The time t is preferably the length of time during the second step when the amount of heat absorbed by the molded body M2 becomes zero. This makes it possible to more effectively increase the heat resistance and strength of the molded body M2.

[0062] The time t is preferably between 150 seconds and 3500 seconds. This allows for a more effective improvement in the heat resistance and strength of the molded body M2.

[0063] The cellulose derivative is preferably a cellulose ester. This allows for a more effective improvement in the heat resistance and strength of the molded article M2.

[0064] The cellulose derivative is preferably an incompletely substituted cellulose ester. This allows for a more effective improvement in the heat resistance and strength of the molded article M2.

[0065] The system comprises a molding unit 2, which is a molding machine that molds a material M1 containing a cellulose derivative into a molded body M2; a warming cabinet 4, which performs a treatment on the molded body M2 formed by the molding unit 2, maintaining it at a first temperature T1 (°C) for a time t (seconds); and a conveying unit 3, which is a conveying machine that transports the molded body M2 from the molding unit 2 to the warming cabinet 4. When the phase transition point Tg of the molded body M2 is A (°C), the first temperature T1 (°C) is between A-10°C and A+50°C. As a result, the molded body M2 can exhibit excellent properties. In other words, by undergoing treatment in the warming cabinet 4, it is environmentally friendly and the heat resistance and strength of the molded product M3 can be sufficiently increased.

[0066] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto. [Examples]

[0067] Next, specific embodiments of the present invention will be described. [7] Preparation of raw materials The following items were prepared to manufacture material M1.

[0068] Cellulose (manufactured by Nippon Paper Industries (KC Floc, W-50GK)) Acetic acid: (Manufactured by Fujifilm Wako Pure Chemical Industries (Acetic Acid)) Propionic anhydride: (Manufactured by Fujifilm Wako Pure Chemical Industries (Propionic anhydride)) Stearic acid: (Manufactured by Fujifilm Wako Pure Chemical Industries (Stearic Acid)) Perchloric acid (manufactured by Fujifilm Wako Pure Chemical Industries (perchloric acid)) 1,4-Dioxane (manufactured by Fujifilm Wako Pure Chemical Industries (1,4-dioxane)) Methanol (manufactured by Fujifilm Wako Pure Chemical Industries (methanol)) Isopropyl alcohol (manufactured by Fujifilm Wako Pure Chemical Industries (Isopropyl Alcohol))

[0069] [8] Manufacturing of molded articles using raw materials (Example 1) First, 5.0 g of stearic acid and 5.0 mL of propionic anhydride were placed in a three-necked flask and reacted at 100°C for 1 hour under a nitrogen atmosphere to synthesize acid anhydrides of stearic acid and propionic acid. Then, 100 mL of 1,4-dioxane was added, and the temperature of the reaction solution was lowered to 50°C. After that, a mixed solution of cellulose activated with acetic acid, 120 μL of perchloric acid, and 50 mL of 1,4-dioxane was added and the mixture was stirred at 50°C. After 2 hours, the reaction solution was transferred from the three-necked flask to a beaker, and the reaction was stopped by dropping 1.5 L of methanol / water mixture (methanol:water = 1:1 vol) as a poor solvent. The precipitated solid was filtered by suction, and the filtrate was washed with isopropyl alcohol and then with water. Subsequently, the cellulose derivative (material M1) was obtained by drying under reduced pressure at 100°C.

[0070] The material M1 obtained as described above was put into the hopper 211 shown in Figure 1, and the manufacturing system 1 was activated to produce the molded product M3.

[0071] The temperature of the material M1 when it is supplied from the injection unit 21 to the clamping unit 22 is set to 250°C.

[0072] The temperature of the molded body M2 when it was removed from the clamping unit 22 was 200°C. Furthermore, the phase transition temperature Tg of molded body M2 was 110°C.

[0073] The temperature of the molded body M2 when it was brought into the warming cabinet 4 was 90°C. The temperature T (°C) during processing in the warming cabinet 4 was set to 100°C, and the time t (seconds) for maintaining the temperature T (°C) was set to 600 seconds (10 minutes).

[0074] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.14 J / g. Through this process, the molded product M3 of Example 1 was obtained.

[0075] (Example 2) Except for setting the temperature T (°C) in the processing performed by the insulated cabinet 4 to 110°C, the molded product M3 of Example 2 was obtained in the same manner as in Example 1.

[0076] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.13 J / g.

[0077] (Example 3) Except for setting the temperature T (°C) in the processing performed by the insulated cabinet 4 to 120°C and the time t (seconds) for maintaining the temperature T (°C) to 480 seconds (6 minutes), the molded product M3 of Example 3 was obtained in the same manner as in Example 1.

[0078] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.08 J / g.

[0079] (Example 4) Except for setting the temperature T (°C) in the processing performed by the insulated cabinet 4 to 130°C and the time t (seconds) for maintaining the temperature T (°C) to 2880 seconds (48 minutes), the molded product M3 of Example 4 was obtained in the same manner as in Example 1.

[0080] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.98 J / g.

[0081] (Example 5) Except for setting the temperature T (°C) in the processing performed by the insulated cabinet 4 to 140°C and the time t (seconds) for maintaining the temperature T (°C) to 1980 seconds (33 minutes), the molded product M3 of Example 5 was obtained in the same manner as in Example 1.

[0082] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 1.01 J / g.

[0083] (Example 6) Except for setting the temperature T (°C) in the processing performed by the insulated cabinet 4 to 150°C and the time t (seconds) for maintaining the temperature T (°C) to 1560 seconds (26 minutes), the molded product M3 of Example 6 was obtained in the same manner as in Example 1.

[0084] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.57 J / g.

[0085] (Example 7) Except for setting the temperature T (°C) in the processing performed by the insulated cabinet 4 to 160°C and the time t (seconds) for maintaining the temperature T (°C) to 2100 seconds (35 minutes), the molded product M3 of Example 7 was obtained in the same manner as in Example 1.

[0086] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.74 J / g.

[0087] (Example 8) Except for setting the temperature T (°C) in the processing performed by the insulated cabinet 4 to 140°C and the time t (seconds) for maintaining the temperature T (°C) to 1200 seconds (20 minutes), the molded product M3 of Example 8 was obtained in the same manner as in Example 1.

[0088] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.60 J / g.

[0089] (Example 9) Except for setting the first temperature T1 (°C) in the process performed by the insulated cabinet 4 to 140°C and the time t1 (seconds) for maintaining the first temperature T1 (°C) to 2400 seconds (40 minutes), and setting the second temperature T2 (°C) to 120°C and the time t2 (seconds) for maintaining the second temperature T2 (°C) to 900 seconds (15 minutes), the molded product M3 of Example 9 was obtained in the same manner as in Example 1.

[0090] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 1.00 J / g.

[0091] (Example 10) Except for setting the first temperature T1 (°C) in the process performed by the insulated cabinet 4 to 140°C and the time t1 (seconds) for maintaining the first temperature T1 (°C) to 900 seconds (15 minutes), the second temperature T2 (°C) to 120°C and the time t2 (seconds) for maintaining the second temperature T2 (°C) to 1800 seconds (30 minutes), the molded product M3 of Example 10 was obtained in the same manner as in Example 1.

[0092] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.60 J / g.

[0093] (Example 11) Except for setting the first temperature T1 (°C) in the processing performed by the insulated cabinet 4 to 140°C and the time t1 (seconds) for maintaining the first temperature T1 (°C) to 900 seconds (15 minutes), the second temperature T2 (°C) to 150°C and the time t2 (seconds) for maintaining the second temperature T2 (°C) to 1200 seconds (20 minutes), the molded product M3 of Example 11 was obtained in the same manner as in Example 1.

[0094] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.90 J / g.

[0095] (Comparative Example 1) A molded product M3 of Comparative Example 1 was obtained in the same manner as in Example 1, except that the temperature T (°C) in the processing performed by the insulated cabinet 4 was set to 170°C and the time t (seconds) for maintaining the temperature T (°C) was set to 1140 seconds (19 minutes).

[0096] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.13 J / g.

[0097] (Comparative Example 2) A molded product M3 of Comparative Example 2 was obtained in the same manner as in Example 1, except that the temperature T (°C) in the processing performed by the insulated cabinet 4 was set to 180°C and the time t (seconds) for maintaining the temperature T (°C) was set to 480 seconds (8 minutes).

[0098] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.14 J / g.

[0099] (Comparative Example 3) A molded product M3 of Comparative Example 3 was obtained in the same manner as in Example 1, except that the first temperature T1 (°C) in the processing performed by the insulated cabinet 4 was set to 140°C, the time t1 (seconds) for maintaining the first temperature T1 (°C) was set to 2400 seconds (40 minutes), the second temperature T2 (°C) was set to 170°C, and the time t2 (seconds) for maintaining the second temperature T2 (°C) was set to 1200 seconds (20 minutes).

[0100] The average enthalpy change per unit time of the molded body M2 during processing in the warming cabinet 4 was 0.13 J / g.

[0101] [9] Rating The molded articles produced by the methods described above for each example and each comparative example were evaluated as follows.

[0102] [9-1] Heat resistance evaluation Measurements were taken in accordance with JIS K 7191-2, and evaluations were performed according to the following criteria. ◎: 100℃ or more and 150℃ or less ○: 80℃ or higher and less than 100℃ ×: 50℃ or higher, but less than 80℃

[0103] [9-2] Strength (impact resistance) evaluation Measurements were taken in accordance with JIS K 711-1, and evaluations were performed according to the following criteria. ◎: 10kJ / m 2 More than 20kJ / m 2 below ○: 8kJ / m 2 More than 10kJ / m 2 less than ×: 2kJ / m 2 More than 8kJ / m 2 less than

[0104]

[10] Overall rating As shown in Table 1 in Figure 4, in Examples 1 to 11, when the phase transition point of the molded article is A (°C), the requirement that the first temperature T1 (°C) in the second step is between A - 10°C and A + 50°C is satisfied, and therefore the resulting molded article can exhibit excellent heat resistance and durability.

[0105] On the other hand, in Comparative Examples 1 and 2, when the phase transition point of the molded article is A (°C), the requirement that the first temperature T1 (°C) in the second step is between A-10°C and A+50°C is not satisfied. Therefore, the resulting molded articles cannot exhibit excellent heat resistance and durability. The same result was obtained when the material of molded body M2 was replaced with other types of cellulose derivatives. [Explanation of Symbols]

[0106] 1...Manufacturing system, 2...Molding section, 3...Conveying section, 4...Insulated cabinet, 21...Injection unit, 22...Clamping unit, 41...Chamber, 42...Heater, 211...Hopper, 212...Cylinder, 213...Outer cylinder, 214...Screw, 215...Motor, 216...Heater, 217...Mouth section, 221...Fixed mold, 222...Movable mold, 223...Cavity, 411...Opening / closing section, M1...Material, M2...Molded body, M3...Molded product

Claims

1. The first step is to form a molded body from a material containing a cellulose derivative, The process includes a second step of producing a molded product by performing a process on the molded body generated in the first step, maintaining it at a predetermined temperature range for a predetermined time t, A method for producing a molded article, characterized in that, when the phase transition point of the molded article is A (°C), the temperature range in the second step is A - 10°C or higher and A + 50°C or lower.

2. A method for producing a molded article according to claim 1, wherein the time t is the length of time in the second step that exceeds the peak of heat absorption of the molded article.

3. A method for producing a molded article according to claim 1, wherein the time t is the length of time in the second step such that the amount of heat absorbed by the molded article is 0.0001 W / g or less.

4. A method for producing a molded article according to claim 1, wherein the time t is 150 seconds or more and 3500 seconds or less.

5. A method for producing a molded article according to any one of claims 1 to 4, wherein the cellulose derivative is a cellulose ester.

6. A method for producing the molded article according to claim 5, wherein the cellulose derivative is an incompletely substituted cellulose ester.

7. A molding machine for forming a molded body from a material containing a cellulose derivative, A warming cabinet that performs a process on the molded body formed by the molding section, maintaining it at a predetermined temperature range for a predetermined time t, The system includes a conveyor that transports the molded body from the molding section to the warming cabinet, A manufacturing system characterized in that, when the phase transition point of the molded article is A (°C), the temperature range is A - 10°C or higher and A + 50°C or lower.

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