WO2020162387A1

WO2020162387A1 - Mixing apparatus, foaming apparatus, and foam-particle manufacturing method

Info

Publication number: WO2020162387A1
Application number: PCT/JP2020/003897
Authority: WO
Inventors: 恭亮村上
Original assignee: 株式会社カネカ
Priority date: 2019-02-06
Filing date: 2020-02-03
Publication date: 2020-08-13
Also published as: JPWO2020162387A1

Abstract

The purpose of the present invention so to evenly mix materials to be mixed between an upper layer and a lower layer by moving the materials to be mixed between the upper layer and the lower layer. A mixing apparatus according to the present invention has at least a first stirring impeller (32) and a second stirring impeller (33) in stirring blades (30), the first stirring impeller (32) and the second stirring impeller (33) are inclined with respect to a horizontal surface and have inclined angles (θ1, θ2) that are different from each other, and, in top view, the first and second stirring impellers (32, 33) do not overlap with each other.

Description

Mixing device, foaming device and method for producing expanded particles

The present invention relates to a mixing device, a foaming device, and a method for producing expanded particles.

A mixing device is known which includes a container for containing the mixture and which mixes the mixture with a stirring blade provided in the container.

For example, Patent Document 1 discloses a stirring blade for stirring and mixing gas and liquid. The stirring blade disclosed in Patent Document 1 has a configuration in which a plurality of upper and lower blades are radially attached to a rotating shaft so as to form a gap between opposed surfaces of a pair of upper and lower blades. The pair of upper and lower blades are formed such that the distance between them becomes narrower or wider in the rotation direction of the blades.

Also, Patent Document 2 discloses a pre-foaming device that heat-foams the resin particles while mixing the thermoplastic synthetic resin particles as a material to be mixed with a stirring blade. The pre-foaming device disclosed in Patent Document 2 includes a scraping plate at the tip of the stirring blade. This scraping plate is provided in a direction substantially vertical to the stirring blade.

JP, 2014-226633, A JP-A-1-301210

However, when the stirring blade disclosed in Patent Document 1 is applied to a mixing device for mixing an object to be mixed (for example, particles), it is technically difficult for the object to be mixed to move between an upper layer and a lower layer in a container. The present inventors have found that there is a problem. That is, even if stirring is performed by the stirring blade, the mixture to be mixed in the upper layer does not easily move to the lower layer and remains in the upper layer. Further, the mixture to be mixed in the lower layer does not easily move to the upper layer and remains in the lower layer. Therefore, in the stirring blade disclosed in Patent Document 1, there is room for improvement in that the materials to be mixed are mutually moved between the upper layer and the lower layer and are uniformly mixed between the upper layer and the lower layer.

Further, when the stirring blade disclosed in Patent Document 1 is applied to the pre-foaming device disclosed in Patent Document 2, since the resin particles are difficult to be uniformly mixed between the upper layer and the lower layer, the resin particles are uniform. It turns out that there is also a technical problem in that it is not heated. Therefore, the expansion ratio of the resin particles tends to vary.

An object of one embodiment of the present invention is to realize a mixing device and a foaming device capable of mutually moving an object to be mixed between an upper layer and a lower layer to uniformly mix the upper layer and the lower layer. ..

In order to solve the above problems, the mixing device according to an aspect of the present invention is a container that stores a mixed object, a plurality of stirring blades that stir the mixed object, and a rotating shaft that rotates the stirring blade, And having at least first and second blades with respect to the stirring blade, the first and second blades being inclined with respect to a horizontal plane and having different inclination angles from each other, It is characterized in that the first and second blades do not overlap each other in a top view.

According to one aspect of the present invention, the material to be mixed can be mutually moved between the upper layer and the lower layer, and can be uniformly mixed between the upper layer and the lower layer.

It is a figure which shows typically the schematic structure of the prefoaming apparatus which concerns on Embodiment 1 of this invention. The structure of the stirring blade with which the pre-foaming apparatus which concerns on Embodiment 1 of this invention was shown, 201 is a side view, 202 is the AA sectional view taken on the line of 201, 203 is the BB line of 201. FIG. It is a figure for explaining the operation mechanism of the 1st and 2nd stirring blade with which the prefoaming device concerning Embodiment 1 of the present invention was equipped, 301 is the 1st and 2nd stirring blade at the time of rotation, respectively. FIG. 3 is a side view for explaining the action of FIG. 3, 302 is a top view showing respective rotation regions of the first and second stirring blades during rotation, and 303 is a flow of foamed particles during rotation of the stirring blade. It is the figure which showed typically. The structure of the stirring blade with which the pre-foaming apparatus which concerns on Embodiment 2 of this invention was shown, 401 is a top view, 402 is a side view, 403 sees one stirring blade from the opposite side to a rotating shaft. It is a figure which shows the structure. The structure of the prefoaming apparatus which concerns on Embodiment 3 of this invention is shown typically, 501 is a sectional view and 502 is a top view which shows an internal structure. The structure of two types of stirring blades provided in the pre-foaming device according to Embodiment 4 of the present invention is shown, 601 is a top view, 602 is a side view, and 603 is one of the two types of stirring blades. FIG. 6 is a side view showing a detailed configuration of one stirring blade, 604 is a side view showing a configuration of the one stirring blade viewed from the side opposite to the rotation axis, and 605 is one of the two types of stirring blades. FIG. 6 is a side view showing a detailed configuration of the other stirring blade, and 606 is a side view showing a configuration of the other stirring blade as viewed from the side opposite to the rotation axis. It is a figure which shows the premise structure of the prefoaming apparatus to be used about an Example, a reference example, and a comparative example, 701 is a sectional view, 702 is a top view which shows an internal structure. It is an image figure which shows the evaluation result of the fluidity and stirring mixing property of the foamed particles in an Example, a reference example, and a comparative example.

The material to be mixed, which is the target of the mixing apparatus according to the present embodiment, is not particularly limited as long as it is a substance that can be mixed by a stirring blade, but a solid is preferable. Particularly preferably, the material to be mixed is a particulate solid. The mixing apparatus according to the present embodiment has a specific structure of the stirring blade used for mixing the materials to be mixed, so that the materials to be mixed are mutually moved between the upper layer and the lower layer, and uniform between the upper layer and the lower layer. Can be mixed with. In the following, a foaming device using expanded particles as a mixture, particularly a pre-foaming device, will be described as an example. The pre-foaming device described later has a configuration including the mixing device according to the present embodiment. Needless to say, the mixing device according to the present embodiment is not limited to that applied to the pre-foaming device described later.

[Embodiment 1]
FIG. 1 is a diagram schematically showing a schematic configuration of a pre-foaming device 10 (mixing device) according to the first embodiment. As shown in FIG. 1, a pre-foaming device 10 according to the present embodiment includes a foaming container 1 (a container for containing a material to be mixed), a rotary shaft 20, a stirring blade 30, a motor 4, and a measuring tank 5. A discharge door 6, a steam supply line 7, an exhaust line 8 and a steam drain discharge line 9 are provided.

The foam container 1 is partitioned into a steam chamber S and a pre-foaming chamber T provided above the steam chamber S. A steam supply line 7 and a steam drain discharge line 9 are connected to the steam chamber S. Further, to the pre-foaming chamber T, the measuring tank 5 and the exhaust line 8 are connected. A fixed amount of foamed particles is stored in the measuring tank 5.

Further, in the pre-foaming chamber T, a rotary shaft 20, a stirring blade 30, and a motor 4 are provided. The stirring blade 30 is a member for stirring the foamed particles in the pre-foaming chamber T. The rotating shaft 20 is a shaft for rotating the stirring blade 30, and is rotated by driving the motor 4. Further, the discharge door 6 is provided in the pre-foaming chamber T.

The stirring blade 30 extends in the horizontal direction with respect to the rotating shaft 20. Then, in the direction in which the rotary shaft 20 extends, the rotary shaft 20 is arranged in multiple stages with a predetermined gap. Thereby, the expanded particles can be efficiently stirred.

The expanded particles (first-stage expanded particles) in the measuring tank 5 are in a state where air is contained therein by injecting compressed air, for example, and the internal pressure of the air is higher than 1 atm. In the pre-foaming device 10, the foamed particles are introduced from the measuring tank 5 into the pre-foaming chamber T of the foaming container 1 and agitated by the stirring blade 30. Further, steam is supplied from the steam supply line 7 to the steam chamber S of the foam container 1. Then, the steam supplied to the steam chamber S flows into the pre-foaming chamber T. As described above, in the foam container 1, the steam in the steam supply line 7 is supplied from the bottom portion to the pre-foaming chamber T. The expanded particles in the pre-expansion chamber T are heated by the steam supplied from the bottom while being stirred by the stirring blade 30. Then, it is heated and expanded to obtain two-stage expanded particles having a predetermined expansion ratio. The obtained two-stage expanded particles are taken out through the discharge door 6.

Further, the steam supplied from the bottom of the pre-foaming chamber T is discharged to the outside of the foam container 1 through the exhaust line 8 after the second-stage foaming is completed. Further, the steam drain generated during the second-stage foaming is discharged to the outside of the foam container 1 via the steam drain discharge line 9.

Although not shown in FIG. 1, the pre-foaming device 10 pre-foams the foaming container 1 in order to prevent blocking of the foamed particles (fusion of the foamed particles) generated during stirring by the stirring blade 30. A baffle (baffle plate) may be provided in the chamber T. The baffle may have any shape as long as it can prevent the foamed particles from blocking.

Here, as described above, in the foaming method in which the foamed particles are heated by the steam supplied from the bottom while being stirred by the stirring blades 30 in the pre-foaming chamber T, the expansion ratio of the two-stage expanded particles in the foam container 1 is increased. Variation easily occurs. The cause of such variations in the expansion ratio is that the expanded particles are not uniformly heated in the pre-expansion chamber T.

Therefore, the inventor of the present application diligently studied the problem of uniform heating of the expanded particles, focusing on the stirring and mixing property of the expanded particles by the stirring blade 30 in the pre-expansion chamber T. As a result, the shape of the stirring blade 30 that can improve the fluidity of the expanded particles in the pre-expansion chamber T both in the vertical direction and in the horizontal direction was found. The pre-foaming device 10 according to the present embodiment is characterized by the shape of the stirring blade 30.

2 shows the structure of the

stirring blade

30, 201 in FIG. 2 is a side view, 202 in FIG. 2 is a sectional view taken along the line AA in 201 in FIG. 2, and 203 in FIG. 2 is 201 in FIG. FIG. 6 is a sectional view taken along line BB in FIG.

As shown by 201 to 203 in FIG. 2, the rotary shaft 20 is provided with a mounting portion 21 for mounting the stirring blade 30. Further, the stirring blade 30 includes two

blade portions

30a and 30b arranged symmetrically with respect to the rotation shaft 20.

The mounting portion 21 may have, for example, a fitting recess that fits with the ends of the

wings

30a and 30b on the rotary shaft 20 side. The stirring blade 30 is attached to the mounting portion 21 by fitting the ends of the

blade portions

30 a and 30 b on the rotary shaft 20 side and the fitting recesses of the mounting portion 21. Further, for example, the

wings

30a and 30b may be directly attached to the rotary shaft 20 by welding or the like.

Here, the stirring blades 30 are arranged so as to be separated from each other on the inner wall and the bottom surface of the foam container 1. That is, the length L of the stirring blade 30 is smaller than the inner diameter (diameter) of the foam container 1 in the direction perpendicular to the rotating shaft 20. In the configuration in which the stirring blade 30 is in contact with the inner wall or the bottom surface of the foam container 1, the stirring blade 30 does not rotate smoothly due to friction due to contact with the inner wall or bottom surface of the foam container 1, which adversely affects the stirring performance. Is.

Pre-expansion apparatus 10 according to the present embodiment, for the same stirring blade 30, the first agitating blade 32 (first blade) and a second agitation blade 33 of a length r ₂ of the length r ₁ ( It is characterized by having at least a second blade. As shown by 201 in FIG. 2, the first stirring blade 32 and the second stirring blade 33 constitute a blade portion 30a having a length r, and the first stirring blade 32 is the second stirring blade. It is arranged inside the blade 33 (on the side of the rotary shaft 20).

Then, the first stirring blade 32 and the second stirring blade 33 are inclined with respect to the horizontal plane and have different inclination angles. And the inclination angle theta ₁ with respect to the horizontal plane of the first stirring blade 32 is different from the inclination angle theta ₂ with respect to the horizontal plane of the second stirring blade 33. In the configuration shown in 201 to 203 of FIG. 2, the first stirring blade 32 and the second stirring blade 33 are mutually seen when viewed from the end on the side opposite to the rotating shaft 20 (the inner wall side of the foam container 1). There is a positional relationship where they intersect.

Further, the inclination angle θ ₁ of the first stirring blade 32 with respect to the horizontal plane is an acute angle. The inclination angle θ ₂ of the second stirring blade 33 with respect to the horizontal plane is an obtuse angle. Therefore, the first stirring blade 32 is configured to incline downward in the rotation direction of the stirring blade 30. Further, the second stirring blade 33 is configured to be inclined upward in the rotation direction of the stirring blade 30.

FIG. 3 is a diagram for explaining the action mechanism of the first stirring blade 32 and the second stirring blade 33. Reference numeral 301 in FIG. 3 is a side view for explaining the action of each of the first stirring blade 32 and the second stirring blade 33 during rotation. Further, reference numeral 302 in FIG. 3 is a top view showing respective rotating regions of the first stirring blade 32 and the second stirring blade 33 during rotation. Further, 303 in FIG. 3 is a diagram schematically showing the flow of foamed particles when the stirring blade 30 rotates.

As described above, the first stirring blade 32 has an acute inclination angle θ _{1 and} is inclined downward in the rotation direction. Therefore, as indicated by 301 in FIG. 3, during the rotational operation of the stirring blade 30, the first stirring blade 32 acts so as to scrape up the foamed particles in the pre-foaming chamber T.

On the other hand, the second stirring blade 33 has an obtuse inclination angle θ _{2 and} is inclined upward in the rotation direction. Therefore, as indicated by 301 in FIG. 3, the second stirring blade 33 acts so as to scrape the foamed particles in the pre-foaming chamber T during the rotating operation of the stirring blade 30.

Further, as indicated by reference numeral 302 in FIG. 3, the rotation area A of the first stirring blade 32 and the rotation area B of the second stirring blade 33 do not overlap each other in a top view seen from the direction of the rotation shaft 20. .. From this, it can be said that the first agitating blade 32 and the second agitating blade 33 are in a positional relationship that does not overlap each other in a top view seen from the direction of the rotating shaft 20. The set of the first stirring blade 32 and the second stirring blade 33 is provided for each of the plurality of stirring blades 30. In a top view seen from the direction of the rotating shaft 20, the plurality of first stirring blades 32 may have a positional relationship within the rotation region A. That is, in the top view seen from the direction of the rotating shaft 20, the plurality of first stirring blades 32 may or may not overlap. Similarly, in the top view seen from the direction of the rotation shaft 20, the plurality of second stirring blades 33 may have a positional relationship that is contained within the rotation region B, and may overlap or may overlap. You don't have to.

Here, in the pre-foaming device 10, the foamed particles move upward in the rotation region A of the inner first stirring blade 32 shown by 302 in FIG. On the other hand, in the rotation region B of the outer second stirring blade 33 shown by 302 in FIG. 3, the foamed particles move downward. Therefore, as indicated by 303 in FIG. 3, during the rotating operation of the stirring blade 30, the flow F to the foamed particles in the pre-foaming chamber T is caused by the above-described actions of the first stirring blade 32 and the second stirring blade 33. Occurs. The flow F is a flow that rises inside the vicinity of the rotary shaft 20 and descends outside the rotary shaft 20. As a result, in the pre-foaming device 10, the foamed particles in the pre-foaming chamber T mutually move between the upper layer and the lower layer, so that the stirring and mixing property is improved.

Therefore, according to the pre-foaming apparatus 10 according to the present embodiment, the stirring blade 30 improves the fluidity of the expanded particles in the pre-foaming chamber T both in the vertical direction and in the horizontal direction. As a result, since the expanded beads are heated uniformly, it is possible to obtain the two-stage expanded particles having a small variation in expansion ratio. Further, since the variation of the foaming ratio is reduced by the structure of the stirring blade 30, the cost of the prefoaming device 10 is low.

The tilt angles θ ₁ and θ ₂ may be different from each other and can be appropriately set according to the type of the mixture to generate the flow F described above. Particularly, when the mixture is particles such as expanded particles, it is preferable that one of the inclination angles θ ₁ and θ ₂ is an obtuse angle and the other angle is an acute angle, for example, as shown in 201 to 203 of FIG. The configuration may be mentioned.

Further, which of the tilt angles θ ₁ and θ ₂ is an obtuse angle or an acute angle can be appropriately set according to the rotation direction of the stirring blade 30 and the like. For example, when the rotation direction of the stirring blade 30 is opposite to the rotation direction shown in 201 and 202 of FIG. 2, the inclination angle θ ₁ of the first stirring blade 32 is set to an obtuse angle and the inclination of the second stirring blade 33 is changed. The angle θ ₂ may be an acute angle.

Further, the tilt angles θ ₁ and θ ₂ are preferably tilt angle θ ₁ +tilt angle θ ₂ =180°. When the tilt angles θ ₁ and θ ₂ are set in this way, the first stirring blade 32 and the second stirring blade 33 have a line-symmetrical positional relationship when viewed from the end opposite to the rotary shaft 20. Has become. Therefore, during the rotating operation of the stirring blade 30, the expanded particles in the pre-expansion chamber T move uniformly upward and downward. Therefore, the expanded particles in the pre-expansion chamber T can be more stably moved to each other between the upper layer and the lower layer.

Further, in order to uniformly move the expanded particles upward and downward during the rotating operation of the stirring blade 30, the area of the rotation region A of the first stirring blade 32 is equal to that of the rotation region B of the second stirring blade 33. It is preferably the same as the area. As a result, the area where the foamed particles are scraped up becomes substantially the same as the area where the foamed particles are scraped down, so that the foamed particles move uniformly upward and downward.

Therefore, the length r ₂ of the first stirring blade 32 lengths r ₁ and second agitating blade 33, the area of the rotation range A is set to be the same as the area of the rotation range B Is preferred. More specifically, in the direction perpendicular to the rotational axis 20, the length _{r 1} and a ratio of _{r 2} _r 1: _{r 2} is preferably 5: 1, more preferably 6: 5-9 4 It is ˜8:2, particularly preferably 7:3.

The tilt angle θ ₁ may be any angle as long as it can cause the action of scraping the expanded particles by rotation. The inclination angle θ ₁ is preferably 10 to 80°, more preferably 30 to 60°, and particularly preferably 40 to 50°.

Further, the tilt angle θ ₂ may be any angle as long as it can cause the action of scraping the expanded particles by rotation. The inclination angle θ ₂ is preferably 100 to 170°, more preferably 120 to 150°, and particularly preferably 130 to 140°.

[Embodiment 2]
Another embodiment of the present invention will be described below. For convenience of description, members having the same functions as the members described in the above embodiment will be designated by the same reference numerals, and the description thereof will not be repeated. 4 shows the structure of the stirring blade 30 provided in the pre-foaming apparatus according to the present embodiment, 401 in FIG. 4 is a top view, 402 in FIG. 4 is a side view, and 403 in FIG. It is a figure which shows the structure seen from the opposite side to the rotating shaft 20 about one stirring blade 30.

As shown by 401 to 403 in FIG. 4, in the pre-foaming device according to the present embodiment, the rotary shaft 20 is provided so that the multi-stage stirring blades 30 form a spiral shape. Different from As indicated by 401 in FIG. 4, the second-stage stirring blade 30 has a positional relationship in which it is rotated from the first-stage stirring blade 30 by an angle α in a direction opposite to the rotation direction. As a generalization, in a top view, the n-th stage stirring blade 30 has a positional relationship in which it is rotated from the (n-1)th stage stirring blade 30 by an angle α in a direction opposite to the rotation direction. With such a positional relationship, the multistage stirring blades 30 form a spiral shape extending in the direction of the rotary shaft 20.

In the present embodiment, the n-th stage stirring blade 30 may have a positional relationship in which it is rotated by an angle α in the rotation direction from the (n-1)-th stage stirring blade 30. In this case, the multistage stirring blades 30 will have a spiral shape in the direction opposite to that of FIG.

As described above, in the present embodiment, the stirring blades 30 extend in the horizontal direction and are arranged in multiple stages on the rotary shaft 20 with a predetermined gap. The multistage stirring blade 30 is provided on the rotary shaft 20 so as to form a spiral shape. Even with such a configuration, the foamed particles in the pre-foaming chamber can be mutually moved between the upper layer and the lower layer. Particularly, in the pre-foaming device according to the present embodiment, the mixing and stirring performance of the foamed particles is improved by arranging the stirring blades 30 in a spiral shape.

Further, the angle α formed by the n-th stage stirring blade 30 and the (n-1)th stage stirring blade 30 in a top view can be appropriately set according to the number of stages (n) of the stirring blades. The angle α obtained by 180°÷the number of steps (n) is preferably 10° to 60°, more preferably 10° to 45°, and particularly preferably 10° to 30°.

[Embodiment 3]
Still another embodiment of the present invention will be described below. For convenience of description, members having the same functions as the members described in the above embodiment will be designated by the same reference numerals, and the description thereof will not be repeated. FIG. 5 schematically shows the configuration of the pre-foaming device according to the present embodiment, 501 in FIG. 5 is a sectional view, and 502 in FIG. 5 is a top view showing the internal configuration.

As shown by 501 and 502 in FIG. 5, the pre-foaming device according to the present embodiment is different from the first and second embodiments in the arrangement of the multistage stirring blades 30. As shown by 501 and 502 in FIG. 5, the n-th stirring blade 30 and the (n-1)-th stirring blade 30 have a positional relationship orthogonal to each other in a plan view.

Even with the multi-stage stirring blades 30 arranged in this way, the expanded particles in the pre-expansion chamber can be moved to each other between the upper layer and the lower layer.

[Embodiment 4]
Still another embodiment of the present invention will be described below. For convenience of description, members having the same functions as the members described in the above embodiment will be designated by the same reference numerals, and the description thereof will not be repeated. FIG. 6 shows the configurations of two types of stirring

blades

30A and 30B provided in the pre-foaming device according to the present embodiment. 601 in FIG. 6 is a top view and 602 in FIG. 6 is a side view. Further, 603 in FIG. 6 is a side view showing the detailed configuration of the

stirring blade

30B, and 604 in FIG. 6 is a side view showing the configuration of the stirring blade 30B as seen from the side opposite to the rotary shaft 20. Further, 605 of FIG. 6 is a side view showing the detailed configuration of the

stirring blade

30A, and 606 of FIG. 6 is a side view showing the configuration of the stirring blade 30A viewed from the side opposite to the rotary shaft 20.

In the pre-foaming devices according to Embodiments 1 to 3, the same stirring blade 30 was provided with the first stirring blade 32 and the second stirring blade 33. However, the pre-foaming device according to the embodiment of the present invention is not limited to the first to third embodiments, and may have any configuration that satisfies the following (a) and (b). (A) The first stirring blade 32 and the second stirring blade 33 are provided for one or more stirring blades 30. (B) The first stirring blade 32 and the second stirring blade 33 do not overlap each other when viewed from the top when viewed from the direction of the rotary shaft 20. In other words, regarding the above (a), the first stirring blade 32 and the second stirring blade 33 may be provided for the same set (in other words, a unit group) of one or more stirring blades. .. In other words, the second stirring blade 33 may be provided on the same or different stirring blade as the stirring blade on which the first stirring blade 32 is provided. As shown by 601 to 606 in FIG. 6, the pre-foaming apparatus according to the present embodiment is the point that the first stirring blade 32 and the second stirring blade 33 are not provided for the same stirring blade. Different from the first embodiment. That is, in the pre-foaming device according to the present embodiment, the stirring blade 30A provided with the first stirring blade 32 and the stirring blade 30B provided with the second stirring blade 33 are different.

Each of the

stirring blades

30A and 30B includes a main body shaft portion 31. The main body shaft portion 31 is attached to the attachment portion 21 of the rotary shaft 20. The first stirring blade 32 is provided on the main body shaft portion 31 of the stirring blade 30A, while the second stirring blade 33 is provided on the main body shaft portion 31 of the stirring blade 30B. The first stirring blade 32 attached to the stirring blade 30A is arranged closer to the rotating shaft 20 than the second stirring blade 33 attached to the stirring blade 30B. More specifically, in the top view seen from the direction of the rotary shaft 20, the positional relationship between the first stirring blade 32 and the second stirring blade 33 satisfies the following (i) and (ii). (I) In the top view, the rotation area of the first stirring blade 32 and the rotation area of the second stirring blade 33 do not overlap. (Ii) In the top view, the rotation region of the first stirring blade 32 fits within the annular locus that is the rotation region of the second stirring blade 33.

Further, as indicated by 604 and 606 in FIG. 6, the inclination angle θ ₂ of the second stirring blade 33 with respect to the horizontal plane is an obtuse angle. Further, as indicated by 606 in FIG. 6, the inclination angle θ ₁ of the first stirring blade 32 with respect to the horizontal plane is an acute angle. Therefore, the first stirring blade 32 is configured to incline downward in the rotation direction of the stirring blade 30. Further, the second stirring blade 33 is configured to be inclined upward in the rotation direction of the stirring blade 30.

Further, as shown by 601 and 602 in FIG. 6, the

stirring blades

30A and 30B are arranged in multiple stages so as to be staggered with a predetermined interval. In other words, the sets of stirring blades including the

stirring blades

30A and 30B are arranged in multiple stages. In the set of stirring blades, the stirring blades 30A are arranged below the stirring blades 30B.

Also, the second-stage stirring blade 30B has a positional relationship in which it is rotated from the first-stage stirring blade 30A by an angle α on the side opposite to the rotation direction. Generally speaking, in a top view, the n-th stage stirring blade 30B has a positional relationship in which it is rotated from the (n-1)th stage stirring blade 30A by an angle α in a direction opposite to the rotation direction. With such a positional relationship, the

multistage stirring blades

30A and 30B form a spiral shape extending in the direction of the rotation shaft 20.

Note that, in the present embodiment, the n-th stage stirring blade 30B may have a positional relationship in which it is rotated by an angle α in the rotation direction from the (n-1)-th stage stirring blade 30A. In this case, the

multistage stirring blades

30A and 30B form a spiral shape in the direction opposite to 602 in FIG.

As described above, in the pre-foaming device according to the present embodiment, the first stirring blade 32 and the second stirring blade 33 are attached to the same set of two

adjacent stirring blades

30A and 30B. The second stirring blade 33 is provided on a stirring blade 30B different from the stirring blade 30A on which the first stirring blade 32 is provided. In the pre-foaming device according to the present embodiment, a plurality of sets of one or more stirring blades (that is, a set of two

stirring blades

30A and 30B) are provided, and the sets are the same. And the 1st stirring blade 32 and the 2nd stirring blade 33 incline with respect to a horizontal surface, and have mutually different inclination angles (theta) ₁ and (theta) ₂ . In addition, the

stirring blades

30A and 30B are arranged in multiple stages so as to be staggered with a predetermined gap therebetween. That is, the set including the two

stirring blades

30A and 30B is arranged in multiple stages.

Even with such a structure, the expanded particles in the pre-expansion chamber can be moved to each other between the upper layer and the lower layer. In particular, in the pre-foaming device according to the present embodiment, the mixing and stirring performance of the foamed particles is improved by arranging the

stirring blades

30A and 30B in a spiral shape.

The angle α formed by the n-th stage stirring blade 30B and the (n-1)th stage stirring blade 30A in a top view can be appropriately set according to the number of stages (n) of the stirring blades. The angle α obtained by 180°÷the number of steps (n) is preferably 10° to 60°, more preferably 10° to 45°, and particularly preferably 10° to 30°.

(Regarding the foamed particles put into the foam container 1)
The foamed particles to be put into the foaming container 1 are not particularly limited as long as they are foamed particles that require two-stage foaming. For example, the foamed particles include thermoplastic resin foamed particles.

The base resin of the expanded thermoplastic resin particles used in the present embodiment is not particularly limited as long as it is a generally known expandable thermoplastic resin. Examples of the thermoplastic resin include polyolefin resins, polyester resins, polystyrene resins, polyphenylene ether resins, polyamide resins, and mixtures thereof. The thermoplastic resin is preferably a polyolefin resin or a polyester resin. Examples of polyester resins include aliphatic polyester resins, aromatic polyester resins, and aliphatic aromatic polyester resins. Specific examples of the polyester resin include polyhydroxyalkanoate, polybutylene succinate (PBS), poly(butylene adipate-co-butylene terephthalate) (PBAT), polyethylene terephthalate (PET), and the like. Further, polyhydroxyalkanoates include poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate) (P3HB), poly(3-hydroxybutyrate-co-). -3-hydroxyvalerate) (PHBV), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P3HB4HB), poly(3-hydroxybutyrate-co-3-hydroxyoctanoate), poly It is at least one selected from the group consisting of (3-hydroxybutyrate-co-3-hydroxyoctadecanoate). Among these, polyolefin resin is preferably used. That is, it is preferable that the expanded particles to be placed in the expanded container 1 are polyolefin resin expanded particles.

An embodiment in which a polyolefin resin is used as a base resin for thermoplastic resin particles will be described below. The base resin of the thermoplastic resin particles that can be used in this embodiment is not limited to the polyolefin resin.

The above-mentioned polyolefin resin is a resin containing 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more of an olefin unit. Specific examples of the polyolefin resin include polyethylenes such as high-density polyethylene, medium-density polyethylene, low-density polyethylene, linear low-density polyethylene, and low-molecular-weight polyethylene; propylene homopolymer; ethylene-propylene random copolymer; Α-Olefin-propylene random copolymers such as ethylene-propylene-1-butene random copolymer and propylene-1-butene random copolymer, and polypropylenes such as α-olefin-propylene block copolymer; propylene Other polyolefin homopolymers such as homopolymer and polybutene; and the like. These may be used alone or in combination of two or more.

Among them, the ethylene-propylene random copolymer, the ethylene-propylene-1-butene random copolymer, and the propylene-1-butene random copolymer exhibit good foamability when they are used as expanded particles. , Preferably used.

In addition to the polyolefin resin, other thermoplastic resins, such as polystyrene, polybutene, and ionomer, are mixed in the base resin of the polyolefin resin foamed particles as long as the characteristics of the polyolefin resin are not lost. May be.

Further, the polyolefin resin is usually melted by using an extruder, a kneader, a Banbury mixer, a roll, and the like, and a columnar shape, an elliptical shape, a spherical shape, a cubic shape, a rectangular parallelepiped shape, etc., so that the expanded beads can be easily produced. It is preferable to process the above resin particles in advance. The resin particles are also called pellets.

The weight of one particle of the polyolefin-based resin particles is preferably 0.1 to 30 mg, more preferably 0.3 to 10 mg.

When an additive is added to the polyolefin resin, it is preferable to mix the polyolefin resin and the additive using a blender or the like before the production of the polyolefin resin particles. Specific examples of the additive include a cell nucleating agent (also simply referred to as a nucleating agent). When a hydrocarbon-based foaming agent such as propane, butane, pentane or hexane is used, the nucleating agent may be an inorganic material such as talc, silica, calcium carbonate, kaolin, titanium oxide, bentonite or barium sulfate. Nucleating agents are commonly used. The addition amount of the cell nucleating agent varies depending on the type of the polyolefin resin used and the type of the cell nucleating agent, and therefore cannot be specified unconditionally, but is generally 0.001 part by weight or more relative to 100 parts by weight of the polyolefin resin. It is preferably 2 parts by weight or less.

When using an inorganic foaming agent such as air, nitrogen, carbon dioxide, or water, it is preferable to use the inorganic nucleating agent and/or the hydrophilic substance. When water is used as the dispersion medium of the aqueous dispersion, the polyolefin resin is impregnated with water, and the impregnated water acts as a foaming agent alone or together with other foaming agents.

The hydrophilic substance acts so as to increase the amount of water impregnated in the polyolefin resin. Specific examples of the hydrophilic substance include inorganic substances such as sodium chloride, calcium chloride, magnesium chloride, borax and zinc borate; or glycerin, melamine, isocyanuric acid, melamine-isocyanuric acid condensate; polyethylene glycol, polyethylene oxide, etc. , Polyethers of polypropylene to polypropylene, etc., and polymer alloys thereof; alkali metal salts of ethylene-(meth)acrylic acid copolymers, alkali metal salts of butadiene-(meth)acrylic acid copolymers, Polymers such as alkali metal salts of carboxylated nitrile rubber, alkali metal salts of isobutylene-maleic anhydride copolymer, and alkali metal salts of poly(meth)acrylic acid; These hydrophilic substances may be used alone or in combination of two or more.

The amount of hydrophilic substance added is 0. It is preferably 005 parts by weight or more and 2 parts by weight or less, and more preferably 0.005 parts by weight or more and 1 part by weight or less. By adjusting the type and amount of the hydrophilic substance, the average cell diameter of the polyolefin resin expanded particles can be adjusted.

Furthermore, when manufacturing polyolefin resin particles, if necessary, colorants, antistatic agents, antioxidants, phosphorus-based processing stabilizers, lactone-based processing stabilizers, metal deactivators, benzotriazole-based UV absorbers, benzoate-based light stabilizers. Add additives such as stabilizers, hindered amine light stabilizers, flame retardants, flame retardant aids, acid neutralizers, crystal nucleating agents, amide additives, etc. within a range that does not impair the properties of the polyolefin resin. be able to.

Also, as the foaming agent, it is possible to use volatile hydrocarbon-based foaming agents such as propane, isobutane, butane, pentane and hexane, and inorganic gases such as air, nitrogen, carbon dioxide and water. When an inorganic gas is used, carbon dioxide is preferable because foamed particles having a relatively high expansion ratio can be easily obtained. These foaming agents may be used alone or in combination of two or more kinds.

It is preferable to use water as the aqueous dispersion medium. A dispersion medium obtained by adding methanol, ethanol, ethylene glycol, glycerin or the like to water can also be used as the aqueous dispersant.

In the aqueous dispersion medium, it is preferable to use a dispersant in order to prevent fusion of the polyolefin resin particles with each other. Specific examples of the dispersant include inorganic dispersants such as tricalcium phosphate, tribasic magnesium phosphate, titanium oxide, basic magnesium carbonate, calcium carbonate, barium sulfate, kaolin, talc and clay. Among these, tricalcium phosphate, barium sulfate, and kaolin are more preferable because they can stably disperse the aqueous dispersion containing the polyolefin resin particles in the pressure resistant container even in a small amount.

Also, it is preferable to use a dispersion aid together with the dispersant. Specific examples of the dispersion aid include carboxylate types such as N-acyl amino acid salt, alkyl ether carboxylate, and acylated peptide; alkylsulfonate, alkylbenzenesulfonate, alkylnaphthalenesulfonate, sulfosuccinate. Sulfonate types such as acid salts; sulfated oils, alkyl sulfates, alkyl ether sulfates, alkyl amide sulfates and other sulfate ester types; and alkyl phosphates, polyoxyethylene phosphates, alkyl allyl ether sulfates Anionic surfactants such as phosphate ester type such as salt; and the like. Further, as a dispersion aid, a maleic acid copolymer salt; a polycarboxylic acid type polymer surfactant such as polyacrylate; and a polyvalent salt such as polystyrene sulfonate, naphthalsulfonic acid formalin condensate salt; Anionic polymeric surfactants can also be used.

As the dispersion aid, it is preferable to use a sulfonate type anionic surfactant, and it is further preferable to use one kind or a mixture of two or more kinds selected from alkylsulfonate and alkylbenzenesulfonate. .. Further, it is more preferable to use an alkyl sulfonate, and to use an alkyl sulfonate having a linear carbon chain having 10 to 18 carbon atoms as a hydrophobic group adheres to the expanded particles of the polyolefin resin. It is particularly preferable because the dispersant can be reduced.

Further, in the embodiment of the present invention, one or more kinds selected from tribasic calcium phosphate, tribasic magnesium phosphate, barium sulfate or kaolin as a dispersant, and n-paraffin sodium sulfonate as a dispersion aid may be used in combination. Particularly preferred.

The amount of the dispersant and the dispersion aid used depends on the type or the type and amount of the polyolefin resin used. Usually, the dispersant is preferably added in an amount of 0.1 parts by weight or more and 5 parts by weight or less, and 0.2 parts by weight or more and 3 parts by weight or less with respect to 100 parts by weight of the aqueous dispersion medium. More preferable. The dispersion aid is preferably added in an amount of 0.001 parts by weight or more and 0.3 parts by weight or less, and 0.001 parts by weight or more and 0.1 parts by weight or less with respect to 100 parts by weight of the aqueous dispersion medium. More preferably. Further, in order to improve the dispersibility of the polyolefin resin particles in the aqueous dispersion medium, it is usually preferable to use 20 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the aqueous dispersion medium. With the above structure, the polyolefin resin particles can be stably dispersed in the aqueous dispersion medium in the pressure resistant container.

(Method for producing expanded particles)
The method for producing expanded particles according to the present embodiment has a step of producing expanded particles using the expansion device according to Embodiments 1 to 4 described above. For example, referring to FIG. 1 and 201 and 202 of FIG. 2, the method for producing expanded particles according to the present embodiment includes a step of introducing expanded particles into the pre-expansion chamber T of the expansion container 1, and the expanded particles. While agitating with a plurality of agitating blades 30, while supplying steam to the pre-expansion chamber T and heating, a two-stage foaming step in which the foamed particles are subjected to a two-stage foaming process. It has the 1st stirring blade 32 and the 2nd stirring blade 33 (1st and 2nd blade), and the 1st stirring blade 32 and the 2nd stirring blade 33 incline with respect to a horizontal surface. , And have different inclination angles θ ₁ and θ ₂ .

According to the method for producing expanded particles according to the present embodiment, the stirring blade 30 is stirred to improve the fluidity of the expanded particles in the pre-expansion chamber T both in the vertical direction and in the horizontal direction, so that the expanded particles are heated uniformly. To be done. Therefore, it is possible to obtain the two-stage expanded particles having a small variation in expansion ratio.

The present invention is not limited to the above-described embodiments, but various modifications can be made within the scope of the claims, and embodiments obtained by appropriately combining the technical means disclosed in the different embodiments Is also included in the technical scope of the present invention. Furthermore, a new technical feature can be formed by combining the technical means disclosed in each embodiment.

(Summary)
A mixing device (pre-foaming device 10) according to Aspect 1 of the present invention includes a container (foaming container 1) for containing a material to be mixed, a plurality of stirring

blades

30, 30A, 30B for stirring the material to be mixed, and the stirring blades. A rotating shaft 20 for rotating 30, 30A, 30B, and at least first and second blades (first blade) with respect to the stirring blade (one stirring blade 30, or two

stirring blades

30A and 30B). Stirring blade 32 and a second stirring blade 33), the first and second blades are inclined with respect to the horizontal plane and have different inclination angles θ ₁ and θ ₂ from each other, and As viewed, the first and second blades are configured so as not to overlap each other.

The mixing device (pre-foaming device 10) according to the second aspect of the present invention is configured such that, in the first aspect, the same stirring blade 30 has at least the first and second blades. That is, the first and second blades are provided on the same stirring blade 30.

A mixing device (pre-foaming device 10) according to Aspect 3 of the present invention is the mixing blade (pre-foaming device 10) according to Aspect 1, in which the first blade (first stirring blade 32) is provided with the stirring blade 30A and the second blade ( The stirring blade 30B provided with the second stirring blade 33) has a different structure. That is, the first blade (first stirring blade 32) and the second blade (second stirring blade 33) are provided on the

different stirring blades

30A and 30B, respectively.

In the mixing apparatus (pre-foaming apparatus 10) according to Aspect 4 of the present invention, in any one of Aspects 1 to 3, an inclination angle θ _{1 of} the first blade (first stirring blade 32) with respect to the horizontal plane is an acute angle. The inclination angle θ _{2 of} the second blade (second stirring blade 33) with respect to the horizontal plane is an obtuse angle.

A mixing apparatus (pre-foaming apparatus 10) according to Aspect 5 of the present invention is the mixing apparatus according to any one of Aspects 1 to 4, wherein the stirring blade 30 extends in the horizontal direction, and the rotation is performed at a predetermined interval. The shaft 20 is arranged in multiple stages. In the mixing device, in particular, in the third aspect, the stirring blade 30A provided with the first blade and the stirring blade 30B provided with the second blade are the longitudinal axis of the rotary shaft 20. It is preferable that they are arranged in multiple stages alternately in the direction.

A mixing apparatus (pre-foaming apparatus 10) according to Aspect 6 of the present invention is configured such that, in Aspect 5, the

multistage stirring blades

30, 30A, 30B are provided on the rotary shaft 20 so as to form a spiral shape. Is.

A mixing device (pre-foaming device 10) according to Aspect 7 of the present invention is the mixing device according to any one of Aspects 1 to 6, in which a length r _{1 of} the first and second blades in a direction perpendicular to the rotation axis and ratio _r 1 of r _2: _{r 2} is 5: 5 to 9: configuration 1.

In the foaming device (pre-foaming device 10) according to Aspect 8 of the present invention, the mixture is foamed particles and is provided with the mixing device according to any one of Aspects 1 to 7.

The method for producing expanded particles according to aspect 9 of the present invention includes a step of producing expanded particles (for example, two-step expanded particles) using the expansion device of aspect 8.

Hereinafter, the present invention will be described in more detail with reference to Examples, Reference Examples, and Comparative Examples, but the present invention should not be construed as being limited to these Examples.

FIG. 7 is a view showing a premise structure of a pre-foaming device to be used in Examples, Reference Examples and Comparative Examples, 701 in FIG. 7 is a sectional view, and 702 in FIG. 7 is an upper surface showing an internal structure. It is a figure. As shown by 701 and 702 in FIG. 7, the pre-foaming apparatuses of Examples, Reference Examples and Comparative Examples have a configuration in which the multi-stage stirring blades G are provided on the rotary shaft 20 so as to form a spiral shape. It is a prerequisite. The inner diameter φ of the foam container 1 is 290 mm. Further, the stirring blade G is separated from the inner wall of the foam container 1 and has a length L of 282 mm. The angle α is 30°. Further, the inclination angle of the stirring blade G with respect to the horizontal plane is 45°.

Using the pre-foaming device shown in 701 and 702 of FIG. 7, the stirring and mixing properties of the expanded particles were evaluated. More specifically, first, the foamed container 1 was charged with white foamed particles and black foamed particles so as to form an upper and lower two layers. Then, the fluidity and the stirring and mixing property of the foamed particles when the stirring blade G was rotated at a stirring speed of 75 rpm were visualized and evaluated as the behavior and the color mixing property of the foamed particles of two colors.

(Example)
In the configuration shown in 701 and 702 of FIG. 7, the pre-expansion device in which the stirring blades 30 shown in 201 to 203 of FIG. 2 are applied to the stirring blade G is used to evaluate the fluidity and stirring mixing property of the expanded particles. did. Ratio _r 1 of length _{r 2} of the first stirring blade 32 lengths _{r 1} and the second agitation blade 33: _{r 2} is 7: 3. The inclination angle θ ₁ of the first stirring blade 32 was 45°, and the inclination angle θ ₂ of the second stirring blade 33 was 135°.

(Reference example)
In the configurations shown in 701 and 702 in FIG. 7, the pre-expanding device in which the length L of the stirring blade G was shortened to 250 mm was used to evaluate the fluidity of the expanded particles and the stirring and mixing property.

(Comparative example)
The pre-expansion apparatus shown at 701 and 702 in FIG. 7 was used to evaluate the fluidity and agitating mixability of the expanded particles.

FIG. 8 is an image diagram showing the evaluation results of the fluidity and agitation mixing property of the expanded particles in Examples, Reference Examples, and Comparative Examples.

First, the result of comparison between the comparative example and the reference example will be explained. As shown in FIG. 8, in the reference example using the stirring blade G having the short length L, the white foamed particles appeared at the upper side earlier than in the comparative example using the stirring blade G having the long length L. It was mixed. From this, it was found that the reference example had better stirring and mixing properties than the comparative example.

Further, as a result of the side surface observation while the stirring blade G was rotating, in the reference example, the flow of the expanded particles from the upper side to the lower side was observed in the reference example, but not observed in the comparative example. In the comparative example, the flow of expanded particles in the rotating direction was observed.

As a reason for such a result, it is conceivable that the vertical flow of the foamed particles in the wall portion of the foam container 1 during stirring is hindered by the stirring blade G having a long length L.

As described above, when the length L of the stirring blade G is short, the foamed particles rise in the center of the foaming container 1, while a descending flow occurs on the side wall side of the foaming container 1 to mix up and down. However, when the length L of the stirring blade G is long, the downward flow of the foamed particles on the side wall side of the foamed container 1 is obstructed. Therefore, it is considered that the shorter length of the stirring blade G is advantageous in terms of improving the stirring and mixing property of the expanded particles.

On the other hand, in the production of second-stage expanded particles using an actual pre-expansion device, a discharge process for discharging the second-stage expanded particles to the outside of the pre-expansion device is required. In the discharging step, the particles in the foam container 1 are discharged to the outside together with the cleaning air while rotating the stirring blade G. Therefore, when the length L of the stirring blade G is short, particles in the foam container 1 may remain on the side wall in the discharging step.

Therefore, when the stirring blade G having a short length L is used, the mixing property of the expanded particles due to the mutual movement of the upper layer and the lower layer is ensured, but the particles may not be efficiently discharged out of the apparatus. Further, when the stirring blade G having a long length L is used, the mixing property of the expanded particles is not good, but the particles can be efficiently discharged out of the apparatus.

Therefore, the inventor of the present application has devised a stirring blade having a long length L while ensuring the mixing property of the foamed particles by the mutual movement of the upper layer and the lower layer, and the structure of the stirring blade 30 shown in 201 to 203 of FIG. Was developed. As shown in FIG. 8, in the example in which the stirring blade 30 is applied to the stirring blade G, white foamed particles appear in the upper portion much faster than in the comparative example in which the stirring blade G having a long length L is used. It was then mixed. From this, it was found that the example had better stirring and mixing properties than the comparative example. Further, it was found that the example has the same or better stirring and mixing property as compared with the reference example using the stirring blade G having the short length L.

The present invention can be utilized in the technical field in which the materials to be mixed are required to be mixed, particularly in the technical field in which the stirring technology is used for foaming the resin.

1 Foaming container (container for containing the mixture)
10 Pre-foaming device (mixing device)
20

Rotating Shafts

30, 30A, 30B Stirring Blade 32 First Stirring Blade (First Blade)
33 Second stirring blade (second blade)
θ ₁ , θ ₂ tilt angle

Claims

A container for containing the material to be mixed,
A plurality of stirring blades for stirring the material to be mixed,
A rotating shaft for rotating the stirring blade,
With respect to the stirring blade, having at least first and second blades,
The first and second blades are inclined with respect to a horizontal plane and have different inclination angles from each other,
A mixing device in which the first and second blades do not overlap with each other in a top view.
The mixing device according to claim 1, which has at least the first and second blades for the same stirring blade.
The mixing device according to claim 1, wherein the stirring blade provided with the first blade and the stirring blade provided with the second blade are different from each other.
The inclination angle of the first blade with respect to the horizontal plane is an acute angle,
The mixing device according to any one of claims 1 to 3, wherein an inclination angle of the second blade with respect to the horizontal plane is an obtuse angle.
The mixing device according to any one of claims 1 to 4, wherein the stirring blades extend in the horizontal direction and are arranged in multiple stages on the rotating shaft at predetermined intervals.
The mixing device according to claim 5, wherein the multi-stage stirring blades are provided on the rotary shaft so as to form a spiral shape.
In the direction perpendicular to the rotation axis,
The mixing device according to any one of claims 1 to 6, wherein a ratio of the lengths of the first and second blades is 5:5 to 9:1.
The mixed material is expanded particles,
A foaming device comprising the mixing device according to any one of claims 1 to 7.
A method for producing expanded particles, comprising the step of producing expanded particles using the expansion device according to claim 8.