JPS6230888B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an apparatus for continuously heating chips of thermoplastic synthetic polymers such as polyamide and polyester;
In particular, the present invention relates to a heating device for pre-crystallizing polyester chips by preheating or heating them.

When polyester chips are dried or subjected to solid phase polymerization, if a temperature of 90°C to 130°C or higher is usually applied, the chips will fuse together. This fusion phenomenon occurs because the surfaces of the chips formed by cutting or the like after melt polymerization are not crystallized, and if the surfaces are crystallized, mutual fusion of the chips can be prevented.

Therefore, it is necessary to pre-crystallize the surface of the chip by some method in advance, but according to the experience of the present inventor, any method used to pre-crystallize the surface of the chip does not require a crystallization temperature higher than the glass transition point, especially 90
It is difficult to avoid fusion at temperatures above ~130°C.

In general, the fusion of chips varies, ranging from large chunks like sardines to 2-3 chips. It is obvious that large chunks like rock sardines will cause problems in subsequent processes, and if chips are sold as a final product, even if they are only two or three chips, the commercial value will drop significantly.

For this reason, it is necessary to crush the chips after preliminary crystallization or pass them through a crusher or the like to separate the fused chips individually. However, such a crusher is usually effective for fused chips that are made up of several chips, but it is effective for crushing chips that are made up of several fused chips.
When fused chips of various sizes up to 3 grains are mixed in each chip, the separation efficiency is poor and it is not practical as an operational equipment.

The inventor of the present invention has conducted various studies on heating equipment for continuously pre-crystallizing polyester chips from this standpoint, and has found that if sufficient stirring is performed while the chip surface is crystallized, fusion will occur. The majority of chips have a small number of chips and only a few chips, but if the degree of stirring is not sufficient, lumps of fused chips are likely to occur, and after crystallization has progressed to a certain extent. It was discovered that it is not easy to separate fused chips, leading to the present invention.

That is, the present invention provides an apparatus for continuously or semi-continuously heating thermoplastic polymer chips in a container having a supply port at the top and a discharge port at the bottom and equipped with stirring blades in multiple stages in the vertical direction. A level meter for controlling the chip level in conjunction with the chip supply means is disposed at the upper position of the device, and stirring blades near the level meter are provided at a vertical interval smaller than other positions. It is.

Hereinafter, the present invention will be explained based on the drawings. The figure is a schematic sectional view showing an embodiment of the present invention. In the figure, 1 is a vertical cylindrical container body, with a supply port 2 at its upper end and a discharge port 3 at its lower end.
Furthermore, a level meter 8 is installed at the upper position.
The level meter 8 operates in conjunction with the motor 11 of the rotary feeder 10 connected to the supply port 2 to adjust the chip level in the container. That is, when the tip becomes lower than the position of the detection end 9, the motor 11 is operated to supply the tip to the container body 1, and when the tip becomes higher than the position of the detection end 9, the motor 11 is stopped and the supply of chips is interrupted. In this case, on/off control, etc. may be performed at the upper and lower two point positions. Further, a rotating shaft 4 driven by a motor (not shown) is disposed in the axial direction of the container body 1. The rotating shaft 4 is formed into a hollow shaft, and its upper end is connected to a hot air pipe 12 via a rotary joint or the like, and its lower end is provided with a hot air outlet 5 formed in a conical shape. . 6 is a stirring blade attached to the rotating shaft 4, and 7 is a baffle plate attached to the container body 1. These stirring blades 6 and baffle plates 7 are mounted (installed) densely at a position near the level detection end 9 than at other positions, that is, the mounting interval in the vertical direction is small. Here, the range in which the stirring blades 6 are closely attached varies somewhat depending on the operating conditions, but it requires a height corresponding to the time required for the surface of the chips supplied to the container body 1 to crystallize to a certain extent (depth). The occurrence of fused chips decreases as the crystallization distance from the chip surface, that is, the depth, increases; in the case of polyester, when the temperature exceeds 20 to 40μ, there is almost no fusion of chips until approximately 230℃; The heating time required for this differs depending on whether the method is electric heating, indirect heating using a heating medium, heating gas, direct heating using steam, etc., but generally takes from several seconds to several tens of minutes.
Therefore, when operating in such a way that the supply and discharge of chips are balanced and the chip level is always maintained at a constant state around the upper and lower positions of the level detection terminal 9, the chips will be at a depth of 20 to 40μ from that level position. The mounting density of the stirring blades 6 and the like may be increased over a distance corresponding to the time required for crystallization. Also, in cases where a fixed amount of chips is supplied and discharged at fixed intervals (in this case, it is a continuous method referred to in the present invention), a stirring blade may be installed at the top of the container depending on the time required for the predetermined crystallization. Just increase the density. The present embodiment shown in the figure operates almost by the latter method, and its operation will be explained below. Note that 13 is a nozzle for discharging hot air, 14 is a heater, and 15 is a pump for circulating hot air. Polyester chips stored in a storage tank or hopper 16 are taken out by a rotary feeder 10 and supplied to the container body 1 through a supply port 2. When the chips in the container body 1 reach a position where they are detected by the detection end 9 of the level meter 8, the motor 11 of the rotary leaf feeder 10 is stopped by the signal, and the supply of chips is stopped. On the other hand, heated gas generated by the pump 15, heater 14, etc. passes through the hot air pipe 12, enters the hollow rotating shaft 4 from a rotary joint, etc., is dispersed in all directions from the air outlet 5 at its tip, and is directly applied to the chip. The chip rises while being heated, passes through the discharge nozzle 13, runs from the hot air pipe 12 again to the pump 15, and then to the heater 14, forming a circulation system, and the heated gas heats the chip to 100 to 180°C. At the same time stirring blade 6
The rotation improves heat transfer and prevents temperature unevenness on the chip.

Next, a predetermined amount of chips is taken out from the outlet 3 of the container body 1 by a discharge means such as a valve (not shown), and
Correspondingly, when the chip level falls, the level meter 8 operates and the rotary feeder 10 starts operating, and the chips are fed until they reach the original level position. If we assume that the amount of chips that have entered the rotary feeder 10 from level L to level H before it is driven and stopped by the detection signal from the level meter 8, then the time required for the required crystallization depth (for example, 30μ) is In addition, the distance between the stirring blades and baffle plates installed between level H and level L is set to be smaller than that in other areas, so that the time required for discharging the next chip is shorter than the time required to eject the next chip. Ensure sufficient stirring. For this reason, the newly introduced chips from level L to level H are rapidly heated by the heated gas, and their surfaces begin to crystallize, and at the same time, fusion between the chips begins to occur. ), the spacing between the stirring blades, etc. (in this case, they may be spaced closely not only in the vertical direction but also in the horizontal direction) is small and effective stirring is performed, so there is less fusion between chips and there is no lumpy fusion. No more chips. If the welding zone is not sufficiently cleaned, large numbers of welded chips will occur, and in some cases, the entire welded zone will be fused and cannot be discharged. In addition, the fused chips generated in the fused zone cannot be separated sufficiently by subsequent stirring, and furthermore, a large amount of force is required, which is undesirable from the viewpoint of handling, operation, cost, etc., and there is a drawback that a large amount of powdered chips is generated. . Therefore, it is preferable that the fusion zone is located as much as possible in the upper part of the container body 1, at least in a position above the center. If the discharge interval is shorter than the predetermined crystallization time, the mounting density range may be widened so that the chip region corresponding to the predetermined crystallization time, that is, the fusion zone, can be sufficiently agitated.

As explained above, according to the present invention, the mounting density of the stirring blades in a specific level range is increased, so that the generation of fused chips is reduced, and effective preliminary crystallization can be performed, thereby making it easier to process and handle in the subsequent process. It becomes very easy.

In this example, a hollow rotating shaft was used to supply the heated gas, but the outlet was separated from the rotating shaft and the hot air piping was continuous from the side of the container body. Alternatively, any heating means may be used without being limited to these means. Furthermore, if the chip supply device is one that carries out pneumatic transport directly from the storage tank via a hopper or cyclone, the supply of chips may be controlled by linking the blower, shutter, etc. with a level meter. .

[Brief explanation of the drawing]

The figure is a schematic sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Container body, 2... Supply port, 3... Discharge port, 4... Rotating shaft, 5... Air outlet, 6... Stirring blade, 7... Baffle plate, 8... Level meter, 10... ...Rotary Fida.

Claims (1)

[Claims] 1. In a device that continuously or semi-continuously heats thermoplastic polymer chips in a container that has a supply port at the top and a discharge port at the bottom and is equipped with stirring blades in multiple stages in the vertical direction, A thermoplastic polymer chip characterized in that a level meter is provided to control the chip level in conjunction with a chip supply means, and stirring blades located near the level meter are provided with a smaller vertical installation interval than other positions. heating device.