JP3676686B2 - Stirring and heating type crystallizer for thermoplastic synthetic resins such as polyethylene terephthalate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to chips made of thermoplastic synthetic resin such as polyamide, polyester, etc. whose surface formed by cutting after melt polymerization, etc., such as regenerated pellets, etc., is not crystallized. Is a device that continuously heats the pellets to crystallized pellets, and in particular pelletized polyethylene terephthalate pellets (recycled pellets) so that they can be used for injection molding, blow molding, etc. The present invention relates to a stirring and heating type crystallization apparatus.
[0002]
[Prior art]
In general, when a pellet of polyethylene terephthalate is dried or solid-phase polymerized, a temperature of 90 ° C. to 130 ° C. or higher is likely to cause fusion between the pellets before crystallization.
[0003]
This fusion phenomenon occurs because the surface formed by cutting or the like after melt polymerization is not crystallized. If the surface is crystallized, fusion between pellets before crystallization can be prevented.
[0004]
Therefore, it is necessary to crystallize the cutting surface of the pellet before crystallization by some method in advance.
[0005]
In general, the fusion of pellets before crystallization is various, and there are hundreds or tens of large lumps to two to three. It is clear that it becomes a cause of trouble in the subsequent process when it becomes a large lump, and even if it is 2 to 3 grains (this is called a defective pellet in the text), the crystallized pellet is the final product. In the case of selling, the merchandise value is significantly reduced.
[0006]
The generation of defective pellets that cause fusion decreases as the thickness of the crystallized layer from the surface increases, and when this thickness is 20 to 40 μm or more, almost up to 230 ° C. can cause fusion. The heating time required for this is different between indirect heating by electric heating / heating medium and direct heating by heating gas / steam, but generally requires several seconds to several tens of minutes.
[0007]
In other words, it is extremely important to operate (process) so that the supply and discharge of pellets before crystallization are balanced and always kept in a constant state, and each pellet before crystallization is exposed to the heating environment. It is most desirable to ensure a stable state in which the time to be heated, that is, the time to undergo heating is kept constant.
[0008]
In order to ensure this stable state, in the past, the structure (shape, etc.) in the tank and the structure and number of stirring blades provided in the tank have been devised, but some results have been obtained. There were some problems.
[0009]
An object of the present invention is to mainly solve the following problems among the above problems. That is,
[0010]
(1) The inner peripheral wall surface of the tank (including the inner peripheral wall surface of the screen separator) is deformed by the rotational movement of the stirring blade.
(2) The incidence of defective pellets increases from this deformation.
▲ 3 ▼ Providing stable and good products becomes difficult.
[0011]
While investigating the cause in order to solve the above-mentioned problems, the present inventor found that the distance between the reverse edge 42b of the tip surface of the stirring blade structure 41 and the inner peripheral wall surface of the tank 43 is the same as shown in FIG. Ascertaining that the cause is that it is configured to be the same as the distance between the leading edge 42a of the tip surface of the stirring blade structure 41 and the inner peripheral wall surface of the tank 43, trial and error about eliminating this cause, It has been found that it is very effective that the backward edge of the tip surface of the stirring blade structure 41 is separated from the inner peripheral wall surface of the tank wider than the advanced edge of the tip surface of the stirring blade structure 41.
[0012]
That is, in the conventional structure shown in FIGS. 8 and 9, a part of the pre-crystallization pellet hitting the front surface of the stirring blade when the structure of the stirring blade 41 rotates moves to the outside of the advanced edge 42a of the distal end surface of the lateral arm 44. The two pre-crystallization pellets that merged into the pre-crystallization pellets that originally flowed between the front end surface of the horizontal arm 44 and the inner peripheral wall surface of the tank 43 are merged. Often, the surfaces are in particular in a molten state during the press-fitting due to the fact that they are pressed against each other and follow a path that is released to the rear of the reverse edge 42b of the distal end surface of the lateral arm 44. The inner peripheral wall surface (particularly the screen separator) 43 of the tank is deformed by the increased amount due to the merging and the reaction of the pressing pressure. It had invited the result of bad heating and stirring.
[0013]
Therefore, in order to solve the above problems, the present invention specifically sets the distance between the reverse edge of the tip surface of the stirring blade structure and the inner peripheral wall surface of the tank to the advanced surface of the tip surface of the stirring blade structure. It is constructed wider than the distance between the edge and the inner peripheral wall surface of the tank.
[0014]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In describing the embodiment of the present invention, in order to facilitate understanding, the heating apparatus main body will be described first, and then, the embodiments of the main points according to the present invention will be described.
[0015]
The first embodiment shown in FIGS. 1 to 3 comprises a spherical bottom cylindrical batch tank 2 whose entire outer peripheral surface is encapsulated by a heat insulating material 1, and a coloring pellet master for the top wall of the batch tank 2. An inlet 3 for a batch, an additive for preventing coagulation such as calcium stearate and a pellet before crystallization of polyethylene terephthalate is provided, and a conical screen separator 5 slightly shallower than the bottom 4 inside the spherical bottom 4 of the batch tank 2. A space 6 is formed between the spherical bottom 4 and the screen separator 5, and a discharge port tube 8 with a shutter 7 for opening and closing the crystallized pellet mixed with the master batch for coloring is connected to the lower end of the screen separator 5. From this discharge port tube 8, a crystallized pellet mixed with a mastering batch for coloring (hereinafter simply referred to as crystallized pellet) is formed. The rotating shaft 10 is rotated by a stirring motor (not shown) at the center of the top wall of the batch tank 2 so that the lower end thereof is close to the bottom opening 11 of the screen separator 5. As a reaching position, stirring is performed while returning to the rotating shaft 10 crystallization pellets (hereinafter simply referred to as crystallization pellets) mixed in the master tank for coloring existing in the batch tank 2 and the screen separator 5. A control panel for attaching a large number of stirring blades 13 via a transverse arm 20 and supplying hot air by heating the outside air sucked by a blower 14 on the side of the batch tank 2 by contacting the built-in heater 15 A hot air supply device 17 with 16 is provided, and a hot air inlet 18 of the hot air supply device 17 is opened in the outer wall of the space 6 and a batch unit is provided. The batch type polyethylene terephthalate crystallization apparatus is configured by providing a dust collecting passage 24 for discharging dust that has fallen through the screen separator 5 to the outside by a natural fall at the bottom of the cup 2. The rearward moving edge 21b of the front end surface of the lateral arm 20 that forms the portion is configured to be wider than the distance from the inner peripheral wall surface of the batch tank 2 to the advanced edge 21a of the front end surface.
[0016]
In the first embodiment, first, the blower 14 is rotated and the internal heater 15 is energized at the same time to warm the whole and the stirring blade 13 is rotated. The master batch for ring and calcium stearate are charged up to each fixed amount, and the temperature is adjusted by the control panel 16 of the hot air supply device 17, and the temperature is kept stable until a certain time based on the data. When the completion of crystallization is confirmed through the pellet gauge window 33, supply of hot air and stirring are stopped, and after the stop, the shutter 7 is opened and the crystallized pellets mixed with the mastering batch for coloring are directly or packaged from the outlet pipe 8. The stock is then used and used as needed, for example, from the bag to the molding machine.
[0017]
In the figure, reference numeral 31 is an inspection lid, 32 is a dust outlet, and 33 is a pellet gauge window.
[0018]
In the first embodiment, as described above, the backward edge 21b of the front end surface of the lateral arm 20 forming a part of the stirring blade structure is more than the inner peripheral wall surface of the batch tank 2 to the advanced edge 21a of the front end surface. Since the structure is widely separated, when the stirring blade structure rotates, some of the pre-crystallization pellets in contact with the front surface of the stirring blade 13 are formed on the advanced edge 21a of the distal end surface of the lateral arm 20. Both crystals are formed by joining the pre-crystallization pellets that are shaped to flow into the space between the front end surface of the lateral arm 20 and the inner peripheral wall surface of the batch tank 2, that is, the divergent space. The pellets before forming are not pressed against each other or pressed slightly, or slightly followed by a path that is released to the rear of the backward edge 21b of the distal end surface of the lateral arm 20, and the surface is particularly melted. Condition The pellets in the core do not form a lump, and the inner peripheral wall of the batch tank, especially the screen separator, is not deformed due to the increase due to the above-mentioned merging and the reaction of the pressing pressure, and good heat stirring The result can be obtained.
[0019]
The second embodiment shown in FIGS. 4 to 6 comprises a spherical bottom cylindrical batch tank 2 whose entire outer peripheral surface is encapsulated with a heat insulating material 1, and a coloring pellet master for the top wall of the batch tank 2. Provided with an inlet 3 for a mixture of pellets, an additive for preventing coagulation such as calcium stearate and an uncrystallized polyethylene terephthalate pellet (in the text, simply referred to as pellet before crystallization), and inside the spherical bottom 4 of the batch tank 2 Is provided with a conical screen separator 5 slightly shallower than the bottom 4 to form a space 6 between the spherical bottom 4 and the screen separator 5, and at the lower end of the screen separator 5, the master batch for coloring is crystallized. A discharge pipe 8 with a shutter 7 for opening and closing pellets (simply referred to as “crystallized pellet” in the text) is connected. Crystallized pellets are supplied to a molding machine (not shown), and a rotating shaft 10 that is rotated by a stirring motor (not shown) at the center of the top wall of the batch tank 2 has a lower end of a screen separator 5. Pelletizing crystallization pellets in the upper half of the batch tank 2 around the upper half of the rotating shaft 10 and crystallization pellets (in the text, only the first crystal) A plurality of longitudinal stirring blades 13a for stirring while returning the pellets to the upper side are attached via the transverse arm 20, and in the lower half of the batch tank 2 around the lower half of the rotary shaft 10. In addition, the crystallization pellets such as the coloring masterbatch existing in the screen separator 5 are returned to the upper side (in the text, simply referred to as the late crystallization pellets). A plurality of lateral stirring blades 13b to be agitated are attached via a lateral arm 20, and the outside air sucked by the blower 14 is brought into contact with the side of the batch tank 2 by contacting the built-in heater 15 to generate hot air. A hot air supply device 17 with a control panel 16 to be supplied is provided, and a hot air inlet 18 of the hot air supply device 17 is opened in the outer wall of the space 6 and the dust has fallen to the bottom of the batch tank 2 through the screen separator 5. The batch type polyethylene terephthalate crystallization apparatus is configured by providing a dust collecting passage 24 for discharging by natural fall outside, and the reverse of the tip surfaces of the stirring blades 13a and 13b forming part of the stirring blade structure The edge 21b is configured to be separated from the inner peripheral wall surface of the batch tank 2 more widely than the advanced edge 21a of the tip surface.
[0020]
In the second embodiment, first, the blower 14 is rotated and the internal heater 15 is energized at the same time to warm the whole and the stirring blades 13a and 13b are rotated. The temperature was adjusted by the control panel 16 of the hot air supply device 17 and the temperature stabilized state was continued for a certain time based on the data, and the completion of crystallization of the pellet before crystallization was confirmed by the pellet gauge window 33. At that time, supply of hot air and agitation are stopped, and after stopping, the shutter 7 is opened, and the crystallized pellets mixed with the mastering batch for coloring are packed directly or from the outlet pipe 8, and after stocking, from the bag to the molding machine It is used in usage such as supply.
[0021]
When the shutter 7 is opened and the crystallized pellets are taken out in the usage of the first and second embodiments, if the whole pellets are not taken out and are left slightly toward the bottom of the screen separator 5, they are prevented from solidification for the next use. In addition, it can be used without adding a pelletized master batch for coloring.
[0022]
In the third embodiment shown in FIG. 7, a spherical bottom type cylindrical tank 2 whose entire outer peripheral surface is encapsulated with a heat insulating material 1 is formed, and a pelletized master batch for coloring, calcium stearate, etc. are formed on the top wall of the tank 2. An inlet 3 for a mixed pellet of an additive for preventing solidification and an uncrystallized polyethylene terephthalate pellet (in the text, simply referred to as a pellet before crystallization) is provided, and is slightly inside the spherical bottom 4 of the tank 2 from the bottom 4 A shallow conical screen separator 5 is provided to form a space 6 between the spherical bottom 4 and the screen separator 5, and a crystallized pellet mixed with a master batch for coloring at the lower end of the screen separator 5 (in the text, simply The crystallized pellets) are connected to the downstream pipe 8 and the crystallized pellets are supplied from the downstream pipe 8 to a molding machine (not shown). Further, the rotary shaft 10 rotated by a stirring motor (not shown) is passed through the center of the top wall of the tank 2 so that the lower end of the rotary shaft 10 reaches the vicinity of the bottom port 11 of the screen separator 5. Around the upper half of the tank 2 are mixed crystallization pellets such as a coloring masterbatch in the upper half of the tank 2 (in the text, simply referred to as the previous crystallization pellets). A directional stirring blade 13a is attached via a transverse arm 20, and a coloring masterbatch such as a coloring masterbatch existing in the lower half of the tank 2 and in the screen separator 5 around the lower half of the rotary shaft 10 In the text, it is simply referred to as a late crystallization pellet). Further, a hot air supply device 17 with a control panel 16 for supplying hot air by heating the outside air sucked by the blower 14 in contact with the built-in heater 15 is provided near the tank 2. A hot air inlet 18 is opened in the outer wall of the space 6 and a hot air exhaust port 19 (which can be provided with a filter) for the hot air is provided on the top wall of the batch tank 2. A continuous polyethylene terephthalate crystallizer 25 is constructed by providing a dust collecting passage 24 for discharging dust that has fallen through the screen separator 5 by natural fall to the bottom, and the continuous polyethylene terephthalate crystallizer 25 is injected. The pellet 8 of the injection molding machine main body 26 is arranged above the molding machine main body 26 so that the flow-down pipe 8 of the crystallized pellets of the crystallization apparatus 25 is connected to the pellets of the injection molding machine main body 26. The molding machine 28 is directly connected to the receiving port 27 in a mounted state, and the reverse edge 21b of the tip surfaces of the stirring blades 13a and 13b forming a part of the stirring blade structure is the inner peripheral wall surface of the batch tank 2 To the advanced edge 21a on the front end surface.
[0023]
In the third embodiment, first, the prepared crystallized pellets are filled up to the bottom of the lateral stirring blade 13b in the tank 2, and the molding by the molding machine body 26 is started using this. The built-in heater 15 is energized and the blower 14 and the stirring blades 13a and 13b are rotated to warm the entire tank 2 while filling the pre-crystallization pellets from the charging port 3, and the hot air supply device 17 is filled in this state. The control panel 16 adjusts the temperature to continue the stable temperature state based on the data, so that the pellet before crystallization is crystallized and the crystallized pellet is stably supplied continuously. The pellet gauge window 33 confirms that it has become possible to obtain crystallized pellets in succession at the start in this way, and the pre-filled crystallized pellets. It followed Tsu preparative continuously feeding to a forming machine body 26 from falling port tube 8, thus those subjected to usage, such as obtaining a molded article in a continuous operation.
[0024]
In the second and third embodiments, as described above, the reverse edge 21b of the front end surface of the stirring blade is configured to be separated from the inner peripheral wall surface of the tank 2 to the advanced edge 21a of the front end surface. Therefore, when the stirring blade structure rotates, a part of the pre-crystallization pellets in contact with the front surface of the stirring blade 13 deviates to the outside of the advanced edge 21a of the tip surface of the stirring blade 13, and the stirring blade 13 Between the front end surface of the tank 2 and the inner peripheral wall surface of the tank 2, that is, into the space that widens toward the end, it merges with the pre-crystallization pellets that originally flow into the same space, and the two pre-crystallization pellets do not press against each other A state or a small amount follows a path that is released to the rear of the backward edge 21b of the tip end surface of the stirring blade 13, and the pellet whose core is in a molten state is a nucleus. Can't make lumps as , Also without such an inner circumferential wall surface, especially Sukurin separator tank cause deformed by reaction of mutual pressure increase and jostling by the confluence, is capable of obtaining a result of a good heat stirring.
[0025]
【The invention's effect】
Since the stirring and heating type crystallization apparatus for thermoplastic synthetic resins such as polyethylene terephthalate according to the present invention is as described above, pellets (regenerated pellets) of the thermoplastic synthetic resin such as polyethylene terephthalate and the master batch for coloring. And while stirring with hot air in a state where calcium stearate is charged up to each fixed amount, without causing a situation in which the whole pellet instantly crystallizes in the tank and does not move, Of course, it is possible to surely crystallize, but in particular, the distance between the reverse edge of the tip surface of the stirring blade structure and the inner peripheral wall surface of the tank is set so that the advanced edge of the tip surface of the stirring blade structure and the inner periphery of the tank Since it is configured to be wider than the interval with the wall surface, some of the pre-crystallization pellets in contact with the front surface of the stirring blade 13 are outside the advanced edge 21a on the tip surface of the stirring blade structure. Before crystallization by merging into the pre-crystallization pellets that originally flowed into the space between the tip surface of the stirring blade structure and the inner peripheral wall surface of the tank 2, that is, the divergent space. The pellets are not pressed against each other or pressed slightly, or slightly followed by a path that is released to the rear of the backward edge 21b of the tip surface of the stirring blade structure, and the surface is particularly in a molten state. As a result of good heating and stirring, the inner wall surface of the tank, especially the screen separator, is not deformed by the increase of the above-mentioned merging and reaction of the pressing pressure. It has a remarkable effect that it can achieve the intended purpose completely.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view taken along line 1A-A in FIG.
FIG. 3 is an enlarged perspective view of the main part, similarly. FIG. 4 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 5 is a schematic cross-sectional view taken along line 4B-B in FIG.
6 is an enlarged perspective view of the main part of the present invention. FIG. 7 is a cross-sectional view showing a third embodiment of the present invention.
FIG. 8 is a cross-sectional view showing a main part of a conventional example.
FIG. 9 is a perspective view showing the main part.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Heat insulating material 2 Tank 3 Input port 4 Spherical bottom 5 Screen separator 6 Space 7 Opening / closing shutter 8 Discharge pipe 10 Rotating shaft 11 Bottom port 13 Stirring blade 13a Vertical stirring blade 13b Horizontal stirring blade 14 Blower 15 Heater 16 Control panel 17 Hot air supply device 18 Hot air inlet 19 Exhaust port 24 Dust collection path 25 Crystallizer 26 Injection molding machine main body 27 Pellet receiving 28 Molding machine 29 Shutter for opening and closing 31 Inspection lid 32 Garbage outlet 33 Pellet gauge window

Claims (1)

In a stirring and heating type crystallization apparatus for a thermoplastic synthetic resin pellet having a supply port and a discharge port in a container and having a stirring blade structure in multiple stages inside, the reverse edge of the front end surface of the stirring blade structure and the tank Stirring and heating type crystallization for thermoplastic synthetic resin such as polyethylene terephthalate, characterized in that the distance between the inner peripheral wall and the inner edge of the tank is wider than the distance between the leading edge of the stirring blade structure and the inner peripheral wall of the tank apparatus.

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