JP6943711B2 - Method for manufacturing extruder die, extruder, and resin composition - Google Patents

Description

The present invention relates to an extruder die used for extrusion molding of a resin composition, an extruder, and a method for producing a resin composition using an extruder.

When the resin composition is extruded into a strand shape using an extruder, some components of the resin composition may adhere to the periphery of the discharge hole of the extruder die. Such deposits are sometimes called Mayani and have various adverse effects. For example, if the resin composition is continuously extruded with the meshi attached around the discharge hole, the meshi may grow in a ring shape and become entangled with the strands. If such a meshi is left unattended, it may be mixed in the product, and there is a concern that the quality may be deteriorated due to the mixture of the meshi in the product. Alternatively, the strands may be cut as the ring-grown Mayani separates from the extruder die. Since this occurs frequently several times per hour, it is necessary to constantly monitor it, interrupt molding to remove eyelids, and maintain the extruder die if necessary.

Therefore, various studies have been made conventionally in order to suppress the generation or growth of eyebrows in the die for an extruder (for example, Patent Documents 1 and 2). Patent Documents 1 and 2 disclose a die for an extruder having a mechanism for blowing a gas near a discharge hole from which a resin is extruded to blow off a mesh.

Japanese Unexamined Patent Publication No. 2012-232432 Japanese Unexamined Patent Publication No. 2017-47638

The extruder dies disclosed in Patent Documents 1 and 2 all require a separate mechanism for blowing gas to the gas supply source and the resin discharge port. Therefore, a slightly complicated mechanism is required, which causes an increase in manufacturing cost and maintenance cost of the die for the extruder.

The present invention has been made in view of the above-mentioned conventional problems. The purpose of the die is to suppress the growth of deposits (meyani) near the discharge hole by a simple structure, an extruder die, an extruder using the extruder die, and a resin composition using the extruder. The purpose is to provide a method for manufacturing a product.

As a result of diligent studies, the present inventor has found that when the resin composition is extruded using an extruder, eyebrows grow around the discharge holes of the extruder die and become entangled with the strands, or cause the strands to be cut. The reason for this is that the shape of the Mayani is ring-shaped, and the present invention has been completed. That is, the present invention that solves the above problems is as follows.

The die for an extruder of the present invention includes a discharge surface having one or a plurality of discharge holes for discharging the molten resin in the form of a strand, and one or a plurality of protrusions protruding vertically from the discharge surface. A part of the root portion of the portion is an extruder die that is in contact with the upper part of the outer periphery of each discharge hole.
In the die for an extruder of the present invention, since a part of the root portion of the protruding portion is in contact with the upper part of the discharge hole, the Mayani has a shape in which the upper part is missing, that is, a substantially U-shape and grows in a ring shape. There is no. Therefore, it becomes easy to fall off in the vertical direction, and problems such as the eyebrows getting entangled with the strands and the strands being cut can be reduced.

In the die for an extruder of the present invention, there are a plurality of discharge holes on the discharge surface, the plurality of discharge holes are arranged in a straight line on the discharge surface, and the protrusions are integrally formed parallel to the arrangement direction of the discharge holes. It is preferable that the configuration is as described above.

The extruder of the present invention is an extruder equipped with the extruder die of the present invention. That is, when the resin composition is extruded by the extruder of the present invention, the above-mentioned problems that the Mayani is entangled with the strands and the strands are cut can be solved.

The method for producing a resin composition of the present invention is a method for producing a resin composition in which at least a resin and an additive are charged into the extruder of the present invention and discharged from a die for an extruder to obtain a resin composition.
Since the method for producing the resin composition of the present invention uses the extruder of the present invention, the resin composition is such that when the resin composition is extruded, a mesh is normally generated around the discharge hole of the die for the extruder. Even so, it is useful because it can suppress the growth of Mayani. For example, when the resin is a polyacetal resin and the additive is a graft copolymer in which the main chain is polyethylene and the side chain is an acrylonitrile-styrene copolymer, meshi may occur. , The problem caused by the polymer when extruding such a resin composition can be solved.

According to the present invention, a die for an extruder capable of suppressing the growth of deposits near a discharge hole by a simple structure, an extruder using the die for the extruder, and a resin composition using the extruder are manufactured. A method can be provided.

It is a conceptual diagram which shows the state of the strand extruded by an extruder until it is cut through a water bath. It is a perspective view of the die for an extruder of this embodiment. It is a front view of the die for an extruder shown in FIG. It is a side view of the die for an extruder shown in FIG. It is a front view which shows the state when the resin is extruded by the die for the extruder of this embodiment partially. It is a front view which shows another form of the die for an extruder of this embodiment. It is a front view which shows another form of the die for an extruder of this embodiment. It is (a) front view and (b) side view of the die for an extruder used in the comparative example 2. FIG.

<Extruder die>
The die for an extruder of the present embodiment includes a discharge surface having one or a plurality of discharge holes for discharging the molten resin in the form of a strand, and one or a plurality of protrusions protruding vertically from the discharge surface. A part of the root portion of the protruding portion is in contact with the upper part of the outer periphery of each discharge hole. The upper part of the outer circumference of the discharge hole includes not only the uppermost portion of the outer circumference of the discharge hole but also the vicinity thereof. That is, as will be described later, if the meshi has a substantially U-shape and the grown meshi falls off, the protruding portion does not necessarily have to be formed at the uppermost portion of the outer periphery of the discharge hole. More specifically, when the uppermost portion is set to the 12 o'clock position, the position where the protruding portion and the discharge hole come into contact with each other can be set to a position in the range of 11 to 13 o'clock.

First, an example of an extruder in which the extruder die of the present embodiment is used and peripheral equipment will be described. In FIG. 1, a strand 40 made of a resin composition extruded by an extruder 10 and discharged from an extruder die 12 is cut by a cutter 32 through a water bath 30 containing cooling water to form pellets 42. It conceptually shows how it is made. That is, the strand 40 is extruded from the extruder 10, put into a water bath 30 to be cooled, and then conveyed to a cutter 32 and cut to a predetermined length to become pellets 42. The extruder die 12 of the present embodiment is mounted on the resin discharge port of the extruder 10 used in the extrusion molding process as shown in FIG.

2 to 4 show an example of the extruder die 12 of the present embodiment. The extruder die 12 has a discharge surface 14 having a plurality of discharge holes 18 for discharging the extruded resin composition in the form of strands, and a protrusion 16 protruding vertically from the discharge surface 14. As shown in FIG. 4, the discharge hole 18 communicates with the flow path 20 of the molten resin, and the molten resin extruded from the extruder passes through the flow path 20 and is discharged from the discharge hole 18. Further, although the shape of the discharge hole 18 is circular in FIGS. 2 to 4, it may be a deformed circular shape such as an elliptical shape or an oval shape. However, the shape of the discharge hole 18 is set so that the cross-sectional shape of the strand to be discharged has a desired shape.

The protruding portion 16 is formed so that its root portion is in contact with the upper portion of the outer periphery of each of the discharge holes 18 (see FIG. 3). More specifically, when the extruder die 12 is mounted on the extruder, the root portion of the protrusion 16 is in contact with the upper portion of the discharge hole 18 in the vertical direction. That is, the upper part of the outer circumference of the discharge hole 18 is a portion located above the outer circumference of the discharge hole 18 when the extruder die 12 is mounted on the extruder. Since the root portion of the protruding portion 16 is in contact with the upper portion of the outer periphery of the discharge hole 18, there is no step with the protruding portion 16 in the upper portion of the outer circumference of the discharge hole 18 (see FIG. 4). That is, when the molten resin flowing through the flow path 20 is discharged from the discharge hole 18, the protruding portion 16 does not interfere.
In the present embodiment, a part of the root portion of the protruding portion 16 is in contact with the upper part of the outer circumference of each discharge hole 18, but in other words, the line of intersection between the discharge surface 14 and the protruding portion 16 is the discharge hole. It is in contact with the upper part of the outer circumference of 18.

When the resin composition is discharged from the discharge hole 18 using the extruder die 12 of the present embodiment, even if a mesh is generated around the discharge hole 18, the mesh does not form a ring shape. This is because even if the Mayani tries to grow in a ring shape, the protruding portion 16 in contact with the upper part of the outer circumference of the discharge hole 18 hinders the growth. Then, the eyebrows grow in the portion other than the upper part of the outer circumference of the discharge hole 18. As shown in FIG. 5, the eyelid looks like a substantially U-shaped eyelid 44 with the upper part missing. Since the substantially U-shaped Mayani 44 is missing at the upper part and is not integrated, it is considered that the holding force against falling in the vertical direction is weaker than that of the ring-shaped Mayani having no missing part over the entire circumference. .. Therefore, the substantially U-shaped Mayani 44 will eventually fall off in the vertical direction as the lower portion becomes heavier as it grows. Therefore, it is possible to reduce the amount of eyebrows adhering to the strands and being mixed into the final product (pellets). Further, the ring-shaped meshi is entangled with the strand when it is separated from the discharge surface of the die for the molding machine, which causes the strand to be cut. It is hard to get entangled and the cutting of the strand is suppressed.

In order to prevent the resin discharged from the discharge hole 18 from buffering the lower surface of the protrusion 16, the protrusion direction of the protrusion 16 from the discharge surface 14 is provided so as to be parallel to the direction of the flow path 20 or inclined upward. Is preferable.

The diameter of the discharge hole 18 is, for example, 2.0 to 7.0 mm. The protruding length of the protruding portion 16 protruding from the discharge surface 14 is, for example, 5 to 20 mm.

The material of the die for the extruder of the present embodiment is not particularly limited, and for example, a metal such as stainless steel or cemented carbide can be used. Further, the method for producing the die for an extruder of the present embodiment is not particularly limited except that a protruding portion is formed, and the die for an extruder can be produced in the same manner as a known die for an extruder.

Next, two modified examples of the extruder die of the present embodiment will be shown. In the form shown in FIGS. 2 to 4, the discharge holes 18 are arranged in a straight line on the discharge surface 14, and the protrusions 16 are integrally formed in parallel with the arrangement direction of the discharge holes 18. The present embodiment is not limited to such an embodiment, and for example, as shown in FIGS. 6 and 7, a plurality of protrusions 16A and 16B may be formed for each of the discharge holes 18. The protrusion 16A in FIG. 6 is a rectangular protrusion when viewed from the front, and similarly, the protrusion 16B in FIG. 7 is an arc-shaped protrusion. In either form, the root portions of the protrusions 16A and 16B are in contact with each other at the upper part of the outer circumference of the discharge hole 18. Therefore, the same effects as those shown in FIGS. 2 to 4 are obtained in the forms shown in FIGS. 6 and 7. In FIG. 7, the protrusion 16B is provided so that the outside of the arc faces upward, but the opposite, that is, the outside of the arc may be provided so as to face downward. Even with such a protruding portion, the same effect as that shown in FIG. 7 can be obtained by providing the root portion so as to be in contact with the upper part of the outer periphery of the discharge hole 18.

The width (horizontal direction) of the protruding portion 16A shown in FIG. 6 is preferably a length equal to or larger than the diameter of the discharge hole 18. This is because, when set in this way, the missing portion is increased in the upper part of the substantially U-shaped meshi, and the substantially U-shaped meshi is likely to fall off.
Further, if the arc-shaped protrusion 16B shown in FIG. 7 is an arc along the circumference of the discharge hole 18, the strands discharged from the discharge hole 18 are caught on the lower surface of the protrusion 16B, and stable extrusion cannot be performed. There is a tendency (see Comparative Example 2). Therefore, it is preferable that the radius of curvature of the arc of the protruding portion 16B is larger than the radius of the discharge hole 18 so that the portion in contact with the outer circumference of the discharge hole 18 is reduced.

The above shows a form in which a plurality of discharge holes are provided on the discharge surface, but the number of discharge holes may be one. In that case, naturally there is only one protruding portion in contact with the discharge hole.

<Extruder>
The extruder of the present embodiment is characterized in that the extruder die of the present embodiment is mounted. The extruder of the present embodiment is not particularly limited as long as it is an extruder having an extrusion screw, and examples thereof include a single-screw extruder, a different-direction twin-screw extruder, and a same-direction twin-screw extruder. Since the extruder of the present embodiment is equipped with the extruder die of the present embodiment described above, it is possible to suppress the growth of meshi near the discharge hole of the extruder die. Therefore, the eyebrows are likely to fall off from the strands during extrusion, and it is possible to reduce the mixing of the eyebrows into the final product and the cutting of the strands caused by the eyebrows.

<Manufacturing method of resin composition>
The method for producing a resin composition of the present embodiment is characterized in that at least the resin and additives are charged into the extruder of the present embodiment and discharged from an extruder die to obtain a resin composition. The resin used in the method for producing the resin composition of the present embodiment is not particularly limited, and may be a general-purpose resin or an engineering resin. In addition, there are no restrictions on the additives used, and various stabilizers, various function-imparting agents, various physical property enhancers, and the like can be used. The production method of the present embodiment is particularly effective for producing a resin composition that tends to generate ring-shaped eyelids.

For example, at least a polyacetal resin and a graft copolymer having a main chain of polyethylene and a side chain of an acrylonitrile-styrene copolymer are put into the extruder of the present embodiment described above, and the die for the extruder is charged. A polyacetal resin composition can be obtained by discharging from. When extruding with an extruder when obtaining such a resin composition, a Mayani derived from the graft copolymer tends to be easily generated around the discharge hole of the die for the extruder. Therefore, when extrusion is performed using the extruder of the present embodiment, the die for the extruder of the present embodiment described above reduces the meshiness, and it is possible to suppress the mixing of the meshy in the final product and the cutting of the strands. ..

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

[Example 1]
First, a die for an extruder of the form shown in FIGS. 2 to 4 having a circular discharge hole having a diameter of 4.0 mm and a protrusion length of 10 mm from the discharge surface was prepared. .. Next, this extruder die was mounted on a twin-screw extruder (TEX65 manufactured by Japan Steel Works, Ltd.).
Next, a polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane (melt index (measured at 190 ° C., load of 2160 g): 2.5 g). / 10min)) 100 parts by mass, 7 parts by mass of a graft copolymer whose main chain is polyethylene and whose side chain is an acrylonitrile-styrene copolymer, and a hindered phenol-based antioxidant (product name: Irganox 1010, BASF Japan Co., Ltd.) 0.5 parts by mass was put into the above-mentioned twin-screw extruder and extruded at a barrel set temperature: 200 ° C., a screw rotation speed: 280 rpm, and an extrusion rate: 350 kg / h. Further, as shown in FIG. 1, the extruded strand was conveyed to the cutter 32 via the water bath 30.

[evaluation]
1. 1. Growth of Mayani From the start of extrusion of the resin composition, the growth of Mayani was visually evaluated in the vicinity of the discharge hole of the die for the extruder. The case where the Mayani fell off from the vicinity of the discharge hole during growth was evaluated as ◯, and the case where the Mayani separated from the vicinity of the discharge hole and became entangled with the strand was evaluated as ×. The evaluation results are shown in Table 1.

2. Strand cutting The extrusion process of the resin composition was continued for 60 hours, and the number of times the strands were cut was counted. In addition, the number of strand cuts per hour was calculated. The results are shown in Table 1.

[Comparative Example 1]
The resin composition was extruded in the same manner as in Example 1 except that an extruder die having no protrusion was used. Then, it was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

[Comparative Example 2]
The resin composition was extruded in the same manner as in Example 1 in which the extruder die shown in FIG. 8 was used as the extruder die. Then, it was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1. In the extruder die shown in FIG. 8, the root portion of the protrusion 16 is not in contact with the discharge hole 18 as shown in FIGS. 2 to 3, but the root portion of the protrusion 16 is placed on the upper portion of the discharge hole 18. A part of the protruding portion 16 is hollowed out so as to coincide with the outer circumference of the discharge hole 18. Further, in this comparative example, the strand expanded immediately after the discharge from the discharge hole 18 was caught in the hollowed portion of the protruding portion 16, and stable extrusion could not be performed.

[Comparative Example 3]
Extrusion was performed in the same manner as in Example 1 except that an extruder die provided so that the root portion of the protruding portion was in contact with the lowermost portion of the outer circumference of the discharge hole was used. Then, it was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1. In this comparative example, a situation occurred in which the strand was caught in a protruding portion provided at the lower part and was cut.

From Table 1, it can be seen that in Example 1, the growth of Mayani was suppressed and the strands were not cut. In particular, it was a very excellent result that the strands were not cut even after operating for 60 hours. On the other hand, in Comparative Example 1, the generation, growth, and separation from the discharge surface were repeated, and the strands were cut about twice an hour, which was a practically problematic level. In Comparative Examples 2 and 3, the strands were caught in the protrusions of the extruder die, and continuous extrusion was impossible.

10 Extruder 12 Extruder die 14 Discharge surface 16 Protruding part 18 Discharge hole 20 Flow path

Claims (5)

A discharge surface of the molten resin has a discharge hole of several that discharged in the form of a strand,
A protrusion 1 that protrudes vertically from the discharge surface is provided.
The plurality of discharge holes are arranged in a straight line on the discharge surface, and the protrusions are integrally formed in parallel with the arrangement direction of the discharge holes.
A die for an extruder in which a part of the root portion of the protruding portion is in contact with the upper part of the outer circumference of each discharge hole. A discharge surface of the molten resin has a discharge hole of several that discharged in the form of a strand,
And a multiple protrusions that protrude vertically from the ejection surface,
Each of the plurality of protrusions has an arc shape in front view with respect to the discharge surface, and the radius of curvature of the arc-shaped protrusion is larger than the radius of the discharge hole.
A die for an extruder in which a part of each of the root portions of the plurality of protrusions is in contact with the upper part of the outer circumference of each of the discharge holes. An extruder equipped with the extruder die according to claim 1 or 2. A method for producing a resin composition, wherein at least the resin and the additive are put into the extruder according to claim 3 and discharged from the extruder die to obtain a resin composition. The production of the resin composition according to claim 4 , wherein the resin is a polyacetal resin, and the additive is a graft copolymer having a main chain of polyethylene and a side chain of an acrylonitrile-styrene copolymer. Method.

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