JPH10109350A - Extruder of molten resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the quality of a product by uniformly dispersing the whole temperature of a molten resin and, at the same time, bringing its temperature close to its optimum temperature by a method wherein the molten resin extruded from a screw extruder is further kneaded. SOLUTION: A rotating side agitating part 12 installed at the tip of a screw 3 and a fixed side agitating part 13 installed at the edge face of a barrel compose a kneading device 11. A plurality of projected parts 14 formed on the outer peripheral surface of the rotating side agitating part 12 and a plurality of projecting pins 15 provided on the inner peripheral surface of the fixed side agitating part 13 do not abut against each other and project alternately in the directions opposite to each other. The molten resin extruded by the feeding force of the screw 3 is kneaded properly with a plurality of the projected parts 14 and of the projecting pins 15 between the rotating side agitating part 12 and the fixed side agitating part 13. Thus, the temperature in the molten resin is uniformly dispersed and the unevenness in temperature can be reduced, resulting in stabilizing the quality of a product made out of this molten resin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for melting and extruding a plastic material, and more particularly to a technique for sufficiently adjusting the temperature and uniformity of a molten resin by sufficiently mixing an extruded resin. The present invention relates to an extruder for molten resin.

[0002]

2. Description of the Related Art For example, an extrusion method (melt extrusion method) is a general method in a process of manufacturing a plastic film or the like. FIG. 6 is a cross-sectional view of a conventional single screw extruder as an example of an extruder used for the extrusion method. In FIG. 6, reference numeral 1 denotes a hopper, into which granular or powdery plastic (hereinafter, referred to as “raw material”) as a raw material is supplied. A raw material is supplied from a hopper 1 to a screw 3 provided in a cylindrical barrel (cylinder) 2 by a constant amount at any time.
Is supplied to the screw groove 3a. The screw 3 is connected to an electric motor (not shown) via a gear reducer 4 in the barrel 2.
Is driven to rotate. Band heaters 5 are provided on the outer peripheral surface of the barrel 2 at predetermined intervals from the tip to the root, and the entire barrel 2 is heated. The raw material is extruded from the root toward the tip of the barrel 2 along the screw groove 3a, and is pressurized and melted while being heated.

FIG. 7 is an enlarged side view of the screw shown in FIG. The screw 3 has a function of melting and extruding the plastic and sending it to the die at a constant rate without fluctuation.
The screw 3 basically has a screw groove 3 over its entire length.
There are a constant pitch type screw having a constant pitch a and a pitch decreasing type screw in which the screw groove 3a gradually decreases from the root to the tip. As shown in FIG. 7, one screw 3 is roughly divided into a supply section A at the root, an intermediate melt compression section B, and a measuring section C at the tip. In addition, screw 3
Is formed with an inner hole 3b extending in the axial direction. The groove (screw groove 3a) of the supply section A has a large depth δ, and the depth δ of the groove of the melt compression section B gradually decreases and becomes shallow toward the front end, and the depth δ of the groove of the measurement section C. Is smaller than the depth of the groove of the supply section A and is constant, and plays a role of supplying the raw material, melting and accumulating and kneading the extrusion pressure, kneading, and constant-speed extrusion, respectively. That is, in the barrel 2, the raw material is extruded from the supply section A to the measuring section C, but in the supply section A, the temperature is low and in a solid state. It is in a state where the molten material is mixed. Then, in the final measuring section C, most of the raw material is melted (hereinafter, referred to as “molten resin”), and while receiving a relatively large shearing force due to the screw rotation, a certain amount of the raw material is supplied to the adapter 6 and the die 7 described later. Extrude molten resin.

The adapter 6 is provided with a screen 6a and a breaker plate 6b, and the molten resin is transported to the screen 6a for removing foreign matter at the tip of the barrel 2 and the breaker plate 6b for regulating the flow of the molten resin. . Then, the molten resin is extruded from the die 7 through the screen 6a and the breaker plate 6b. The molten resin extruded from the die 7 is transported to a molding die such as a T die (not shown). As the T-die, for example, there is a straight manifold type, a coat / bunger type or a combination thereof, and the T-die is selected according to a film to be manufactured. The molten resin extruded from the T-die is hot-stretched to a die lip width (die orifice width) of 1/10 to 1/100, and then forcibly cooled to produce a film.

[0005]

In the plastic film manufacturing process, the barrel 2 is heated by the band heater 5 to melt the raw material. The temperature at the time of this heating is set to be higher than the melting temperature of the plastic raw material. However, if this temperature is set higher than necessary, the quality and basic characteristics (physical characteristics) of the manufactured film may be deteriorated. Therefore, it is necessary to perform temperature control and perform manufacturing within a predetermined temperature range.

The temperature control is performed by adjusting the heating by the band heater 5 provided on the outer peripheral surface of the barrel 2 and the cooling of the screw 3. For example, in FIG. 6, a cooling pipe (supply pipe and discharge pipe) 8 is inserted into the inner hole 3b from the left end side in the drawing, and the cooling water is supplied by a circulating device (not shown) through the pipe 8 to the outside. And cooling is performed from the inside of the screw 3. The temperature of the outer peripheral surface of the barrel 2 and the cooling water is constantly monitored by a temperature sensor (not shown).
From the monitored temperature, the melting temperature is set by adjusting the temperature of the band heater 5, adjusting the cooling temperature of the cooling water, and the like.

However, since the screw groove 3a is interposed between the barrel 2 and the screw 3, the temperature is higher on the barrel 2 side and lower on the screw 3 side. Therefore, it is difficult to maintain the temperature of the molten resin at a constant optimum temperature even by the above method, and a temperature gradient always occurs between the barrel 2 and the screw 3.
Therefore, the temperature of the molten resin extruded from such a situation is not uniformly kneaded as a whole, and temperature unevenness occurs. As a result, for example, undissolved raw materials are mixed in the molten resin, and problems such as uneven thickness, foreign matter, discoloration / decomposition phenomenon, transparency, and surface properties are caused, which causes deterioration in product quality.

Therefore, it is conceivable to reduce the temperature gradient by making the depth δ of the screw groove 3a shallow and bringing the barrel 2 and the outer peripheral surface of the shaft of the screw 3 as close as possible. However, since the cross-sectional area of the molten resin is reduced in this method, if the amount of extrusion per unit time is increased, the internal pressure in the molten compression section B increases,
The resin temperature is too high and the plastic material is likely to deteriorate. Further, if the temperature rise is to be avoided, the amount of resin extruded per unit time is reduced, resulting in a disadvantage that production efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. By further kneading a molten resin extruded from a screw extruder, the entire temperature of the molten resin can be uniformly dispersed, and an optimum temperature can be obtained. It is an object of the present invention to provide a molten resin extruder that can stabilize product quality by approaching temperature.

Another object of the present invention is to provide a molten resin extruder capable of improving production efficiency without reducing the amount of extrusion per unit time.

[0011]

According to the present invention, a screw is provided inside a cylindrical barrel, and a resin material extruded by the screw in the barrel is heated and pressurized in the barrel. In the extruder, a fixed stirrer is provided at the tip of the barrel, and a rotating stirrer is provided at the tip of the screw.A plurality of protruding pins are provided on the inner peripheral surface of the fixed stirrer. The outer peripheral surface is provided with a plurality of projecting portions alternately positioned with the projecting pins, and the molten resin extruded by the screw is kneaded with the projecting portions and the projecting pins. Is what you do.

In the above, the clearance between the inner peripheral surface of the fixed stirring unit and the outer peripheral surface of the rotary stirring unit is set to be larger than the clearance between the outer peripheral surface of the shaft of the screw and the outer peripheral surface of the barrel. Is preferred.

The fixed-side stirring section is detachably attached to the tip of the barrel, the rotating-side stirring section is detachably attached to the tip of the screw, and the rotating-side stirring section is fixed within the fixed-side stirring section. When the rotation position is set to the above, the protruding portion is located in the gap between the protruding pins, so that the rotating-side stirring section can be pulled out from the fixed-side stirring section.

Further, it is preferable that the protruding portion provided on the rotation-side stirring section has a tapered shape at the circumferential end.

The molten resin extruder according to the present invention has a kneading device comprising a rotating side stirring section and a fixed side stirring section. The rotating-side stirring unit is fixed to the tip of the screw of the screw extruder, and the fixed-side stirring unit is fixed to the flange on the barrel end face. On the outer peripheral surface of the rotation side stirring unit, a plurality of projecting portions are formed at a predetermined pitch in the circumferential direction and the axial direction,
Similarly, a plurality of protruding pins are provided on the inner peripheral surface of the fixed-side stirring section at a predetermined pitch in the circumferential and axial directions. However, 1
Since the first row of projections is provided between the second row of projection pins and the second row of projection pins, the projections collide with the projection pins even when the rotating stirring section rotates. There is nothing to do. In addition, since a screen and a breaker plate are provided on the flange of the fixed-side stirring section, the molten resin that has been extruded between the screw grooves flows between the rotating-side stirring section and the fixed-side stirring section in the kneading apparatus. The flow velocity decreases, and at this position, the molten resin can be sufficiently kneaded by the plurality of projecting portions and the plurality of projecting pins, and the temperature can be dispersed as a whole and a uniform state can be obtained. In addition, by this kneading, the resin that has been conventionally extruded in the unmelted state can be shifted to the molten state, and the ratio of the unmelted resin can be reduced.

An appropriate gap (play) is provided between the protruding portion and the protruding pin, and the protruding portion and the protruding pin are pointed to each other on the rotating side stirring portion or the fixed side stirring portion. As a result, the region through which the molten resin passes can be sufficiently ensured. Therefore, even when the kneading device is attached to the screw extruder, the production efficiency can be improved because the extrusion amount per unit time is not reduced.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. The same members as those of the above-described conventional example are denoted by the same reference numerals. FIG. 1 is a cross-sectional view showing a screw extruder, FIG. 2 is a cross-sectional view showing an adapter and a die provided at a tip end of the screw extruder, and FIG. 3 is an apparatus for kneading a molten resin which is a feature of the present invention. FIG. 4 is a sectional view showing the configuration, and FIG. 4 is an end view taken in the direction of arrow IV in FIG. The single screw extruder shown in FIG. 1 has basically the same structure as that shown in FIG. However, the present invention is different in that the kneading device shown in FIG. 3 is attached to the tip (right end in the figure) of the screw extruder, and the adapter and the die shown in FIG.

In the screw extruder shown in FIG. 1, granular or powdery plastic (raw material) is supplied from a hopper 1 to a supply section A at the root of a screw 3. Screw 3
It is inserted into a cylindrical barrel (cylinder) 2 and is rotationally driven by an electric motor (not shown) via a gear reducer 4 provided at the left end in the figure. Therefore, the raw material supplied from the hopper 1 is extruded toward the tip of the barrel 2 at the right end in the figure by the feed force generated by the rotation of the screw 3. Band heaters 5 are provided on the outer peripheral surface of the barrel 2 at predetermined intervals, and are heated so that the temperature in the barrel 2 is equal to or higher than the melting point of the raw material.

The raw material supplied to the supply section A is sequentially extruded to the melt compression section B and the measuring section C by the rotation of the screw 3. The screw 3 is fed from the supply section A to the melt compression section B
Since the depth of the screw groove 3a gradually decreases and becomes shallower toward, the raw material is in a state of being gradually compressed toward the front end. Then, in the melt compression section B, the raw material gradually melts, and a state in which the molten material and the unmelted material are mixed exists. Therefore, in the final measuring section C, most of the raw material is melted (hereinafter, referred to as “molten resin”), and a fixed amount of molten resin is extruded into the kneading device 11 while receiving relatively large shearing force due to screw rotation. .

As shown in FIG. 3, a kneading device 11 is provided at the tip of the screw extruder. The kneading device 11 includes a rotating-side stirring unit 12 and a fixed-side stirring unit 13. At the tail end of one rotation side stirring unit 12, a convex screwing portion 12 a is formed, and screwed to the tip of the screw 3. A plurality of projecting portions 14 are provided on the side surface of the rotation-side stirring portion 12 at a predetermined pitch in the circumferential direction.
They are also provided in a line at a predetermined pitch in the axial direction.

On the other hand, the fixed-side stirring section 13 is formed in a cylindrical shape, and a plurality of through holes 1 are formed at predetermined positions of the side section 13c.
3d is drilled. The through holes 13d are also formed at a predetermined pitch in the circumferential direction, and are also formed in a row at a predetermined pitch in the X-axis direction in the figure. A projecting pin 15 is inserted into each through hole 13d from the inner peripheral surface of the side portion 13c toward the outer peripheral surface, and is fixed on the outer peripheral surface by a nut or the like. That is, the head of the protruding pin 15 is exposed in the inner peripheral surface direction of the side portion 13c. Note that a thread groove may be formed in the through hole 13d, and the protruding pin 15 may be screwed into the thread groove. In addition, flanges 13a and 13b that extend in the outer peripheral direction are provided at both ends of the fixed-side stirring section 13, respectively. Then, one flange 13a side of the fixed-side stirring unit 13 is externally inserted into the rotating-side stirring unit 12 from the X-axis (-) direction in the drawing, and is fixed to the flange 2a provided at the tip of the barrel 2 with bolts 16 or the like. .

As shown in FIG. 4, a projecting portion 14 is provided on the outer peripheral surface of the rotating side stirring portion 12. On the outer peripheral surface of the rotation side stirring unit 12 shown in this example, twelve projecting portions 14 are provided, and two protruding portions 14 are constituted by a total of six blocks. In the protruding portion 14, the central angle between adjacent protruding portions 14 in one block is θ1, whereas the central angle θ2 when the blocks are adjacent is set to satisfy θ1 <θ2. I have. The head of the protruding pin 15 can pass through only the block gap α formed by the wide central angle θ2 in the X-axis direction, and cannot pass through the narrow central angle θ1. . Also,
As shown in FIG.
Are provided at each vertex (center angle π / 3) forming a regular hexagon. Also, the block gap α has the same central angle (π / 3) as the protruding pin 15 and
When the fixed side stirring unit 13 is moved in the X-axis direction at the position shown in FIG. 4, attachment or detachment is possible. Also, the rotation side stirring unit 12 rotates,
In the case where the projecting pin 15 and the projecting portion 14 slightly overlap each other when viewed from the direction of FIG. 4, the attachment or detachment of the fixed side stirring unit 13 becomes impossible.

As shown in FIG. 3, the protruding pins 15 are provided in a line in the X-axis direction, and are provided between the first and second rows of protruding pins 15 in the circumferential direction. The first row of projections 14 is located in the first row, and the second row of projections 14 is located between the second row and the third row of projection pins 15. Further, between the protruding portion 14 and the protruding pin 15,
A gap (play) is provided. Therefore, even when the rotation side stirring unit 12 rotates, the projecting portion 14 does not collide with the projecting pin 15. As shown in FIGS. 3 and 4, the molten resin extruded from the tip of the barrel 2 passes between the plurality of projecting pins 15 in the kneading device 11 and the plurality of rotating projecting portions 14. X
It is guided in the axis (+) direction. That is, the gap between the plurality of projecting pins 15 and the plurality of rotating projecting portions 14 is
It is a passage through which the molten resin passes.

Further, it is possible to make the outer peripheral radius r of the rotating side stirring unit 12 smaller than the inner peripheral radius R of the fixed side stirring unit 13. The gap dimension of Rr is larger than the gap between the outer peripheral surface of the shaft portion of the screw 3 and the inner peripheral surface of the barrel 2. In addition, the above-mentioned protruding pin 15 and protruding portion 14 are formed between the outer peripheral surface of the rotating side stirring section 12 and the fixed side stirring section 13.
Is scattered with respect to the inner peripheral surface, so that the occupied volume is not so large. Therefore, since the volume of the gap between the inner peripheral surface of the fixed-side stirring unit 13 and the outer peripheral surface of the rotating-side stirring unit 12 can be increased, the compression force in the kneading device 11 is smaller than that in the barrel 2. It will be extremely small. Further, the end face of the kneading device 11 on the side of the flange 13b is provided with
The adapter 6 and the die 7 are mounted. Since the adapter 6 is provided with the screen 6a for removing foreign substances and the breaker plate 6b for regulating the flow of the molten resin, the molten resin extruded from the kneading device 11
Once accumulated in the kneading device 11. Therefore, the molten resin is more uniformly stirred in the kneading apparatus 11 than in the conventional case, and the temperature unevenness in the molten resin can be reduced. Further, by sufficiently kneading in this manner, the ratio of the unmelted resin can be reduced, and a molten resin having excellent quality can be obtained.

Further, since the molten resin can be uniformly stirred by the kneading device 11, even if the gap between the outer peripheral surface of the screw shaft 3 and the inner peripheral surface of the barrel 2 is made larger than before, the kneading device 11 can be used. Thereby, the resin temperature can be made uniform.
Since the gap between the screw shaft 3 and the barrel 2 can be increased, the extrusion amount of the molten resin per unit time can be increased, and the processing speed can be improved. In addition, since the gap can be increased, an increase in the internal temperature in the melt compression section B can be prevented, and extrusion can be performed at an appropriate temperature.

FIG. 5 is an enlarged perspective view of the protruding portion. FIG.
As shown in FIG. 4, the projecting portion 14 is formed in a shape in which only one set of opposite sides of the six side surfaces of the hexagonal solid shape is extended in the circumferential direction. That is, as shown in FIG. 5, two sets of tapered surfaces 14a, 1a are provided on both end surfaces in the rotation direction.
4b, 14c, and 14d, and a pair of tapered surfaces (for example, between 14a and 14b) are formed to have a convex acute angle. Therefore, when the rotation side stirring unit 12 rotates, the double tapered surface of the protruding portion 14 rotates so as to cut through the mixed resin, so that the load resistance during rotation can be reduced. Therefore, the rotation of the rotation side stirring unit 12 can be made smooth, and the load on the electric motor can be reduced. Therefore, the rotation itself is easily performed smoothly, and the stirring of the molten resin can be further improved. Therefore, the molten resin in the optimum temperature state can be sent to the die 7, and the quality of the product can be stabilized.

In addition, since the molten resin can be made uniform and at an appropriate temperature in the kneading apparatus 11 as described above, the allowable range of the temperature unevenness of the molten resin extruded from the barrel 2 can be widened. Therefore, for example, it is possible to increase the depth δ of the screw groove 3a, so that the feeding force by the screw 3 can be increased. That is, since the amount of extrusion per unit time can be increased, the production efficiency is improved.

In the above-described apparatus for kneading molten resin, the projecting portions 14 and the projecting pins 15 each have three rows. However, the present invention is not limited to this. Depending on the condition, two or less rows may be used, or four or more rows may be used. Further, the molten resin kneading apparatus of the present invention is not limited to a single screw extruder used in a melt extrusion method, and is not limited to a multi-screw extruder, but may be any other thermoplastic resin such as an injection molding machine. It can be used for various extruders for molding resin.

[0029]

According to the present invention described in detail above, the molten resin can be kneaded more than ever, so that the extruded molten resin can be made uniform with less temperature unevenness,
Extrusion at an appropriate temperature is also possible. Therefore, the quality of the product can be stabilized.

Further, since the allowable range of the temperature unevenness of the molten resin can be widened, the depth of the screw groove can be increased to increase the feeding force. Therefore, the amount of extrusion per unit time can be increased, so that the production efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a screw extruder,

FIG. 2 is a cross-sectional view showing an adapter and a die provided at the tip of the screw extruder;

FIG. 3 is a cross-sectional view illustrating one embodiment of a molten resin kneading apparatus according to the present invention.

FIG. 4 is an end view taken in the direction of arrow IV in FIG. 3;

FIG. 5 is an enlarged perspective view of a protruding portion,

FIG. 6 is a sectional view of a conventional single screw extruder,

FIG. 7 is an enlarged side view of the screw,

[Explanation of symbols]

 2 Barrel 3 Screw 3a Screw groove 5 Band heater 11 Kneading device 12 Rotary stirring part 13 Fixed stirring part 13c Side part 14 Protrusion part 14a, 14b, 14c, 14d Tapered surface 15 Protrusion pin A Supply part B Melt compression part C Measurement section α Block gap

Claims (4)

[Claims] 1. A molten resin extruder in which a screw is provided inside a cylindrical barrel, and a resin material extruded by the screw in the barrel is heated and pressurized in the barrel. The fixed-side stirring unit is provided with a rotating-side stirring unit at the tip of the screw, a plurality of projecting pins on the inner peripheral surface of the fixed-side stirring unit, and the projecting pin on the outer peripheral surface of the rotating-side stirring unit. A molten resin extruder, comprising a plurality of staggered projecting portions, wherein the molten resin extruded by the screw is kneaded by the projecting portions and the projecting pins. 2. A clearance between an inner peripheral surface of the fixed stirring portion and an outer peripheral surface of the rotating stirring portion is set to be larger than a clearance between an outer peripheral surface of the shaft portion of the screw and an outer peripheral surface of the barrel. 1
An extruder for the molten resin as described above. 3. The fixed-side stirring section is detachably attached to the tip of the barrel, the rotating-side stirring section is detachably attached to the tip of the screw, and the rotating-side stirring section is fixed within the fixed-side stirring section. The molten resin extruder according to claim 1 or 2, wherein the protruding portion is located in a gap between the protruding pins when the rotation position is set to be such that the rotation-side stirring portion can be extracted from the fixed-side stirring portion. . 4. The molten resin extruder according to claim 1, wherein the protruding portion provided on the rotation-side stirring portion has a tapered end in a circumferential direction.