JPH074833B2 - Melt plasticizer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a melt plasticizing device for thermoplastics applied to an extruder, an injection molding machine, or the like.

(Prior Art) In order to preheat the raw material resin supplied to the melt plasticizer,
Conventionally, a packed bed type heating device as shown in FIG. 2 is installed separately from the melt plasticizing device, and both are used off-line. However, although it may occasionally be directly connected to the melt plasticizing device, generally, the heated raw material resin is batch-transferred to the main body of the melt plasticizing device using a means such as air feeding.

That is, in FIG. 2, reference numeral 1 denotes a filling tank, and hot air heated by the heat exchanger 5 is blown out from the distribution duct 2 below the filling tank 1 by the fan 6, passes through between the resin particles filled inside, and heats the resin particles. .

After the resin particles are heated, hot air is blown from above the filling tank 1 into the fan 6
Is sucked into and circulates. The hot air temperature at this time is controlled by detecting the hot air temperature at the outlet of the heat exchanger 5 by the temperature sensor 7 and controlling the heat exchanger temperature via the temperature adjusting device 8 and the heater power supply circuit.

The heated raw material resin is discharged through the valve 3. The problem with this type of heating device is that the discharge state of the resin in the tank cannot always be kept constant, and therefore the residence time is uneven, so the temperature distribution of the resin particles should be kept constant. Is difficult, and long-term heating is required to keep the temperature of the resin particles constant. This is one of the reasons why the heating device cannot be installed inline.

In addition, since the heating time is inevitably long as described above, when the heating temperature is high, the resin particles in the filling tank stick to each other, and the whole is solidified in the shape of "candy" of the confectionery, resulting in melt plasticization. There is also a problem that it cannot be smoothly sent to the main body of the chemical conversion device. However, if you can drive in normal condition,
Generally, by heating the resin particles in the filling tank, the capacity of the melt plasticizer can be increased by 20 to 30%.

Therefore, a melt plasticizer as shown in FIG. 3 was developed for the purpose of solving the above-mentioned problems while taking advantage of supplying the heated raw material resin to the melt plasticizer. Already proposed by No. 62-51498.

This device is a melt plasticizing device integrally provided in the melt plasticizing device main body for heating while fluidizing the raw material resin in a layered manner, and the resin pellet R in the hopper 11 is driven by the variable speed motor 13. A desired amount is supplied into the fluidized bed heating tank by the fixed amount feeder 12. The supplied resin pellets R flow in layers in a stepwise manner from a plurality of stages of porous dispersion plates 18a, 18b, which are rotatable by hinges 19, 19, .. Reach the resin inlet. While being flowing, the hot air heated by the heat exchanger 5 is supplied to the inside of the fluidized bed heating tank by the fan 6 through the duct 4 and passes through the holes of the dispersion plates 18a, 18b ...
While heating the resin pellet R, it flows upward and returns air holes 40
To circulate through duct 4.

In addition, 7 is a hot air temperature sensor and 8 is a temperature adjusting device.

That is, the heating device shown in FIG. 3 is intended to continuously heat and convey the resin pellets R in layers by inclining the dispersion plates 18a, 18b.

However, in the case of this device, the relationship between the amount of resin conveyed and the inclination angle of the dispersion plate is delicate, and when the heating and melting amount of resin is frequently changed (this state is common in a resin melting and plasticizing device). .), It takes a long time to set the inclination angle of the dispersion plate so as to obtain a predetermined transport amount while maintaining a good flow state. In addition, when the operation is stopped, a small amount of pellets remain on the dispersion plate, which requires cleaning time.

Therefore, although the application of this apparatus is suitable for a large-sized film manufacturing apparatus, it is not suitable for a heating / plasticizing apparatus in which the melting amount or the pellet type is frequently changed, and other measures are required.

(Problems to be Solved by the Invention) A fluidized bed heating apparatus using an inclined dispersion plate shown in FIG.
Compared with the conventional general packed bed heating method shown in the figure, higher temperature heating is possible, for example, in the case of polypropylene resin, the packed bed method can heat up to 80 to 90 ° C, and the fluidized bed method can heat up to 150 to 160 ° C. The heating time is short and the advantage is great. However, as described above, there is a demerit that it is difficult to adjust the inclination angle of the dispersion plate according to the heating amount.

Therefore, the present invention has been made in order to improve this point, and it is an object of the present invention to provide a melt plasticizing apparatus equipped with a fluidized bed heating device in which the amount of resin material conveyed can be easily and arbitrarily adjusted. Is.

(Means for Solving the Problems) Therefore, in the present invention, in the thermoplastic melting and plasticizing apparatus, the present invention is provided with an endless belt which is composed of a ventilation member and rotates, and the raw material resin is layered on the belt. A fluidized bed heating device that heats while moving is connected to a raw material supply unit of the melt plasticizing device main body, which is a means for solving the above problems.

That is, the present invention is to use the dispersion plate in the previously proposed fluidized bed heating device as a belt conveyor.

In addition to the above configuration, there may be a case where a rotary valve with blades that rotates in synchronization with the belt speed is installed near the raw material carrying-out end of the conveyor. Etc. to control the belt speed of the conveyor and the rotation speed of the rotary valve.

(Operation) (1) When changing the fluidized bed dispersion plate from a simple flat plate to a conveyor belt and changing the supply amount of resin pellets,
By simply setting the belt speed to the optimum speed, it is possible to easily change the transfer amount while maintaining the material resin in a good flow state.

Further, even when the operation is stopped, all the pellets can be discharged without remaining on the conveyor belt, which eliminates the need for cleaning.

(2) Since the dispersion plate is an endless belt conveyor instead of a simple porous inclined plate, the resistance of the dispersion plate increases, making it difficult for hot air to pass through the conveyor, and the amount of air that blows around it and passes through the conveyor. However, by installing a rotary valve at the conveyor outlet, a predetermined amount of pellets can be dropped intermittently on the lower conveyor so that hot air can pass through the conveyor well, Improve energy efficiency by preventing blow through.

(3) Further, if a transmitted light detection sensor is provided on the conveyor, it is possible to automatically adjust the conveyor speed based on the detection sensor signal and control so that the transmitted light amount is in a good carrying state. Therefore, it is not necessary to manually adjust the conveyor, and the operation can be simplified.

(Example) Hereinafter, the present invention will be described in detail based on illustrated examples.

FIG. 1 shows a typical embodiment of the present invention, and a fluidized-bed heating device according to this embodiment is connected to the raw material resin inlet of the melt plasticizer main body 100.

In the figure, reference numeral 20 denotes a heating tank, and a raw material discharge port provided in the lower part thereof communicates with a raw material resin charging port of the melt plasticizing apparatus main body 100. A variable speed motor is installed above the heating tank 20.
Pellet R with a feeder 22 driven by 23 in between
, A multistage belt conveyor (hereinafter referred to as a dispersion plate conveyor) 28, 28 ... Is vertically arranged inside the heating layer 20.
... are rotated by being driven by the variable speed motor 29.

The dispersion plate conveyor 28 is composed of a flexible perforated plate or a net of a suitable mesh. Further, the belt speed is adjusted by changing the rotation of each variable speed motor 29, 29 ... In response to a command from the motor rotation adjusting device 34.

At the downstream end of the pellet of each dispersion plate conveyor 28, 28 ...
Rotary valves 31, 31 ... With a desired number of blades are provided with their axes of rotation parallel to the width direction of the dispersion plate conveyors 28, 28. The rotary valves 31 and 31 rotate in synchronization with the belt speeds of the distribution plate conveyors 28, 28 ... Further, light transmission sensors 32, 32 ... Are provided on the upper part of the downstream side of the pellets of the respective dispersion plate conveyors 28, 28.

In the figure, 24a is a duct connected to the return air hole 30 formed in the upper part of the heating tank 20, 24b is a duct connected to the lower part of the heating tank 20, and a blower 26 and a heater 2 are provided between the ducts.
5. A temperature sensor 27 is installed to form a hot air circulation path, and the temperature sensor 27 is connected to a temperature control device. These parts are substantially the same as the corresponding parts of the previously proposed melt plasticizer shown in FIG.

In the above configuration, the resin pellets R in the hopper 21 are conveyed by the feeder 22 driven by the variable speed motor 23, and fall onto the ventilation uppermost dispersion plate conveyor 28 which is rotationally driven by the variable speed motor 29.

On the other hand, the blower 26 sucks the air in the heating tank 20 through the duct 24a, heats it to a predetermined temperature with the heater 25, and blows it into the heating tank 20 through the duct 24b for circulation. The air blown into the heating tank 20 is blown up through the holes of the multistage dispersion plate conveyors 28, 28 ..., and rapidly heats the pellets R on the conveyor in a fluidized state. At the downstream end of the pellets of each conveyor 28, a rotary valve 31 is rotating in synchronization with the conveyor 28, and the pellets R are dropped intermittently to improve the dispersion of the pellets R on the next-stage conveyor and hot air. The hot air is prevented from bypassing from the end of the conveyor belt.

Light transmission sensor 3 provided on top of each dispersion plate conveyor 28, 28 ...
2 indicates the flow status based on the amount of transmitted light.For example, if the amount of transmitted light is too small and the amount of pellets is too large, increase the conveyor speed based on the sensor output, and if the amount of transmitted light is too large and the amount of pellets is too small, Is capable of automatically adjusting the conveyor speed to reduce the conveyor speed.

The pellets R that have flowed on the dispersion plate conveyor and have risen to a predetermined temperature enter the melting plasticizer main body 100 and melt. In the illustrated example, the dispersion plate conveyor 28 is provided in three stages, but the conveyor may have one or more stages.

(Effects of the Invention) As described in detail above, according to the present invention, since the raw material resin is preheated in the fluidized bed state before being introduced into the main body of the plasticizer, energy efficiency is improved and the in-line heating device is improved. Of course, since the pellets are flown on the ventilation belt conveyor in the heating tank, it is easy to adjust the operation even when the pellet heating conditions are changed, and even when the work is completed. Since pellets do not remain in the heating tank, cleaning is not required, which is extremely effective.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an outline of a melting and plasticizing device equipped with a fluidized bed type pellet heating device which is a typical embodiment of the present invention, and FIG. 2 is a conventional packed bed type pellet heating device and plasticizing device. FIG. 3 is a schematic side sectional view showing the relationship of FIG. 3, and FIG. 3 is a schematic side sectional view of a melt plasticizing apparatus provided with the previously proposed fluidized bed pellet heating apparatus. Description of main parts of the figure 20 …… Heating tank 25 …… Heater 26 …… Blower 27 …… Hot air temperature sensor 28 …… Dispersion plate conveyor 29 …… Variable speed motor 30 …… Return air hole 31 …… Rotary valve 32… … Light transmission sensor 34 …… Motor rotation adjustment device 100 …… Melt plasticizer main unit

Claims (1)

[Claims] 1. A fluidized bed heating device in a thermoplastic melting and plasticizing device, which comprises an endless belt which is composed of a ventilation member and which rotates and which heats a raw material resin while moving it in layers on the belt. A melt plasticizer, which is connected to a raw material supply unit of the melt plasticizer main body.