JP5728077B2 - Thermoplastic resin composition pellet manufacturing method, extruder and die plate - Google Patents

Description

  The present invention relates to a method for producing a thermoplastic resin composition pellet, an extruder, and a die plate.

  As one of molding methods for extruding a thermoplastic resin material, extrusion molding using a screw extruder is widely used. Screw extruders include single-screw or multi-screw extruders, and general ones are equipped with screws, cylinders (sometimes called barrels), drive units, heating / cooling units, etc. Corresponding die plates are attached.

  When a thermoplastic resin composition is molded using an extruder, the thermoplastic resin composition adheres and stays around the discharge holes of the die plate to form a lump called “Meani”. This mayani is carbonized and discolored.

  And if extrusion molding is continued for a long time, Mayani gradually adheres and accumulates in the vicinity of the discharge holes of the die plate for the extruder. If left as it is, the carbonized mayani adheres to the strand-like extrudate. This may become a foreign substance in the final product and may deteriorate the quality. Moreover, due to this meany, strand breakage or the like may occur, and stable operation may not be possible.

  For this reason, at the manufacturing site, it is necessary to remove the sticking deposited on the die plate using tweezers or the like. Although the removal process of the main can be performed without stopping the extrusion, the work is complicated because it is a manual operation.

  Thus, there is disclosed a method for preventing the occurrence of mesas that prevents the occurrence of mess when obtaining a thermoplastic resin molded product such as a strand or sheet, and that can achieve improvement in productivity and maintenance of product quality. (See Patent Document 1).

  In addition, as a technique for improving the problem of mess, a method has been disclosed in which a projection nozzle is provided in a discharge hole of a die plate and a strand-like object is pushed out through the projection nozzle (see Patent Document 2).

  According to the techniques described in Patent Document 1 and Patent Document 2, although there is a certain effect on the problem of Meyani, further improvement is required.

JP 2003-019740 A JP 2003-136579 A

  The present invention has been made in order to solve the above problems, and the purpose of the present invention is to prevent the build-up of deposits near the discharge holes of the die plate for the extruder, thereby reducing the quality of the product or stable molding. The object is to provide a technique for suppressing problems such as obstruction.

  The inventors of the present invention have made extensive studies to solve the above problems. As a result, a thermoplastic resin composition in a molten state is molded using an extruder including a die plate having discharge holes that are discharged in a strand shape, and a first gas spraying section that sprays gas onto the discharged strand-shaped material. It has been found that the above problems can be solved by doing so. More specifically, gas is blown from the first gas blowing portion to at least a part of the boundary line between the extruded strand-like material and the upper portion of the opening, and the die plate is on the discharge surface of the die plate, The shortest distance from the lower end of the opening of the discharge hole to the outer periphery of the die plate is found to be 2 mm or more and 5 mm or less, thereby finding that the above problems can be solved, and the present invention has been completed. The present invention provides the following.

  (1) A method for producing a thermoplastic resin composition pellet using an extruder, wherein the molten thermoplastic resin composition is extruded in a strand form from a discharge hole of a die plate provided in the extruder. The gas is blown onto at least a part of the boundary line between the extruded strand-like material and the upper part of the opening on the discharge surface side of the discharge hole, and from the lower end of the discharge hole opening on the discharge surface of the die plate, The shortest distance to the outer periphery of a die plate is 2 mm or more and 5 mm or less, The manufacturing method of the thermoplastic resin composition pellet characterized by the above-mentioned.

  (2) At least a part on the boundary line is a part including a boundary point between the upper end of the opening and the strand-like object, and further includes a boundary point between the lower end of the opening and the strand-like object. The method for producing a thermoplastic resin composition pellet according to (1), wherein gas is also blown to the part.

  (3) A notch is formed on the discharge surface of the die plate, the notch is formed below the position of the opening on the discharge surface, and the lower end of the opening and the strand-like material The gas blown to a part including the boundary point passes through the space notched by the formation of the notch, and the method for producing the thermoplastic resin composition pellets according to (2).

  (4) An extruder comprising: a die plate having discharge holes for discharging a molten thermoplastic resin composition in a strand shape; and a first gas spraying portion for spraying a gas to the discharged strand-like material, The shortest distance from the lower end of the opening of the discharge hole to the outer periphery of the die plate on the discharge surface of the die plate is 2 mm or more and 5 mm or less, and the gas spraying portion is a strand of thermoplastic resin composition in a molten state An extruder that blows gas onto at least a part of the boundary line between the extruded strand-like material and the upper opening on the discharge surface side of the discharge hole.

  (5) The extruder according to (4), wherein at least a part on the boundary line is a part including a boundary point between an upper end of the opening and the strand-like material.

  (6) A second gas spraying unit that sprays a gas from below the position of the opening on the discharge surface toward a part including a boundary point between the lower end of the opening and the strand-like object is further provided (4 ) Or the extruder according to (5).

  (7) A notch is formed on the discharge surface, the notch is formed below the position of the opening on the discharge surface, and the gas blown from the second gas blowing portion is The extruder as described in (6) which passes the space notched by formation of the notch part.

  (8) A die plate having discharge holes for discharging the molten thermoplastic resin composition in a strand shape, from the lower end of the discharge hole opening to the outer periphery of the die plate on the discharge surface of the die plate A die plate whose shortest distance is 2 mm or more and 5 mm or less.

  (9) The die plate according to (8), wherein a notch is formed on the discharge surface, and the notch is formed below the position of the opening on the discharge surface.

  According to the present invention, the problem that the scum accumulated near the discharge hole in the discharge surface of the die plate for an extruder deteriorates the quality of the product or inhibits stable molding is a problem in the prior art. It can be greatly reduced compared to.

It is a figure which shows typically the cross section of the extruder of embodiment. It is a figure which shows the die plate of embodiment typically, (a) is a perspective view, (b) is a front view, (c) is a side view. It is a schematic diagram which shows a mode that gas is sprayed with respect to the thermoplastic resin composition discharged in strand form from the 1st gas spraying part. It is a schematic diagram which shows a mode that gas is sprayed with respect to the outer periphery of the discharge surface of a die plate from a 2nd gas spraying part. It is a graph which shows the number of colored pellets.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment.

<Extruder>
Drawing 1 is a figure showing typically the section of extruder 1 of this embodiment. The extruder 1 includes a hopper 10, a cylinder 11, a screw 12, a die plate 13, a first gas spraying part 14, and a second gas spraying part 15.

The cylinder 11 has a screw 12 disposed therein. Further, the cylinder 11 is provided with a hopper 10 for supplying the thermoplastic resin composition 2 at the base of the screw 12 at the upstream end, and the die plate 13 is connected to the downstream end .

  The usage method of the extruder 1 is demonstrated easily. The thermoplastic resin composition 2 supplied from the hopper 10 is conveyed in the direction of the die plate 13 through the space between the cylinder 11 and the screw 12 by the rotation of the screw 12. In the course of this conveyance, the thermoplastic resin composition 2 is melted by the shearing force received from the cylinder 11 and the screw 12. The molten thermoplastic resin composition 2 is discharged from the die plate 13 in a strand shape. The strand-like thermoplastic resin composition 2 (hereinafter sometimes referred to as a strand-like material) is sprayed with gas from the first gas spraying portion 14 immediately after being discharged. Moreover, gas is sprayed from the 2nd gas spraying part 15 toward the die plate 13 which discharges the thermoplastic resin composition person 2.

  Next, the die plate 13 having discharge holes for discharging the molten thermoplastic resin composition 2 will be further described. The die plate described below is an example of the die plate of the present invention. 2A and 2B are diagrams schematically showing the die plate 13, wherein FIG. 2A is a perspective view, FIG. 2B is a front view, and FIG. 2C is a side view.

  The die plate 13 includes a discharge hole 130 for discharging the molten thermoplastic resin composition 2 in a strand shape, and a notch 131.

  The discharge hole 130 passes through the discharge surface A and the surface opposite to the discharge surface A. The thermoplastic resin composition 2 flows into the discharge hole 130 in a molten state from the opening on the surface opposite to the discharge surface A, and the thermoplastic resin composition 2 is extruded in a strand form from the opening on the discharge surface A side.

  The opening on the discharge surface A side of the discharge hole 130 exists on the discharge surface A. The shortest distance (the distance between Δx = PQ) between the lower end P of the opening on the discharge surface A and the outer periphery of the discharge surface A is 2 mm or more and 5 mm or less. As long as the position of the opening on the discharge surface A side satisfies this condition, the discharge hole 130 may be formed in the die plate 13 in any manner.

  For example, in FIG. 2, the opening on the ejection surface A side and the opening on the opposite surface are present at opposite positions, but the positional relationship between the openings present at both ends of the ejection hole 130 is not particularly limited. In FIG. 2, the discharge hole 130 is a linear hole extending in the direction in which the thermoplastic resin composition 2 flows. However, the discharge hole 130 may extend in a direction shifted by a predetermined angle from the direction in which the thermoplastic resin composition 2 flows. It may be other than a straight line. Therefore, the position of the opening existing on the surface opposite to the discharge surface A and the shape of the flow path through which the thermoplastic resin composition 2 passes can be appropriately set.

  In addition, although FIG. 2 demonstrated the case where the discharge hole 130 was one, the die plate which has multiple discharge holes 130 may be sufficient. In the case where a plurality of discharge holes 130 are provided, the shortest distance is preferably 2 mm or more and 5 mm or less for all the discharge holes. Moreover, it is preferable that gas is sprayed from the 1st gas spraying part and the 2nd gas spraying part with respect to the thermoplastic resin composition 2 discharged from all the discharge holes. In this case, the 1st gas spraying part and the 2nd gas spraying part may be comprised from the several gas spraying part.

  The notch 131 is a stepped notch formed on the discharge surface A. The notch 131 is formed in a step shape so as to penetrate the two side surfaces that connect the discharge surface A and the opposite surface. However, the notch 131 has a notch as long as it does not impair the effects of the present invention described later. The shape of the part 131 is not particularly limited.

  Then, the 1st gas spraying part 14 is demonstrated. FIG. 3 is a diagram schematically illustrating a state in which gas is sprayed from the first gas spraying portion 14 toward the strand-shaped object.

  In the present embodiment, the first gas blowing unit 14 is disposed above the position of the opening of the discharge hole 130 on the discharge surface A. And the position of the gas outlet is adjusted so that the first gas spraying part 14 can spray gas to at least a part on the boundary line between the extruded strand-like material and the upper part of the opening on the discharge surface A. ing. Here, “the boundary line between the extruded strand-like material and the upper part of the opening on the discharge surface A” refers to the boundary line between the outer periphery of the semicircle above the opening and the strand-like material. In the present embodiment, at least a part of the boundary line includes a boundary point between the upper end of the opening and the strand-like object.

In addition, the kind of gas sprayed is not specifically limited, The atmosphere, an inert gas, etc. can be illustrated. Moreover, the gas which the 1st gas spraying part 14 sprays may have humidity and temperature adjusted. Adjustment of humidity and temperature can be performed by a conventionally known control method. Further, the gas flow rate can also be adjusted as appropriate within a range that provides the effects described below. For example, the gas wind pressure is 0. More than 1 MPa 0. It is preferable to adjust to 4 MPa or less. 0. If it is 1 MPa or more, it is preferable for the reason that the cane is cooled and easily peeled off from the die plate . If it is 4 MPa or less, it is preferable for the reason of preventing resin clogging at the discharge hole due to cooling of the die plate. More preferable wind pressure is 0. More than 1 MPa 0. 3 MPa or less.

  The shortest distance from the gas outlet of the first gas blowing unit 14 to the strand is not particularly limited, but is 20 cm or less in the present embodiment. By being 20 cm or less, cooling of the die plate 13 due to the expansion of the gas injection range can be suppressed.

The angle θ ₁ formed by the gas outlet of the first gas blowing section 14, the straight line connecting the upper end of the opening and the boundary point between the strands, and the discharge surface A is in the range of 0 ° to 90 °. However, it is preferably adjusted in the range of 0 ° or more and 60 ° or less. However, in the present invention, it is more important to apply gas to the boundary line between the extruded strand-like material and the upper part of the opening on the discharge surface A than the spray angle.

  Then, the 2nd gas spraying part 15 is demonstrated. FIG. 4 is a diagram schematically showing a state in which gas is sprayed from the second gas spraying portion 15 toward the boundary point between the lower end of the opening present on the discharge surface and the strand-like material.

  The second gas blowing unit 15 is disposed below the position of the opening of the discharge hole 130 on the discharge surface A. In the present embodiment, the shortest distance (Δx = distance between PQ) between the lower end P of the opening on the discharge surface A and the outer periphery of the discharge surface A is 5 mm or less. For this reason, even if there is a gas outlet on the extruder side from the discharge surface A, the boundary point between the lower end of the opening present on the discharge surface and the strand-like material is adjusted by adjusting the direction of the gas to be blown out You can also spray gas. That is, as shown in FIG. 4, by blowing gas near the boundary point, gas can also be blown to the boundary point.

In order to blow gas to the boundary point between the lower end of the opening present on the discharge surface and the strand-like material, a straight line connecting the gas blowing port of the second gas blowing unit 15 and the boundary point, and extrusion of the extruder angle theta ₂ formed by the straight line along the direction is appropriately adjusted within a range that the effect of the present invention, preferably 100 ° or more 150 ° or less.

  It is preferable that the distance between the gas blowing port of the second gas blowing unit 15, the upper end of the opening, and the boundary point between the strands is 20 cm or less. The closer the distance is, the smaller the area irradiated with the gas, and the cooling of the die plate 13 can be suppressed.

  The gas blown from the gas blowing unit 15 passes through a space surrounded by a two-dot chain line. The space surrounded by the two-dot chain line refers to a space that is notched due to the formation of the notch 131.

The kind of gas that can be used is the same as that of the first gas spraying unit 14. Moreover, humidity and temperature may be adjusted. Further, the wind pressure and the like can be appropriately adjusted within a range that does not impair the effects described below. For example, the gas wind pressure is 0. More than 1 MPa 0. It is preferable to adjust to 5 MPa or less. 0. If it is 1 MPa or more, it is preferable for the reason that the cane is cooled and easily peeled off from the die plate . If it is 5 MPa or less, it is preferable for the reason of preventing clogging of the resin composition at the discharge hole due to cooling of the die plate. A more preferable wind pressure is 0.15 MPa or more and 0.35 MPa or less.

  Moreover, it is preferable to spray gas intermittently from the second gas spraying portion 15. Intermittently refers to blowing gas at intervals of a predetermined time. The predetermined time interval may be a fixed interval or may not be a fixed interval. The predetermined time interval can be adjusted as appropriate.

  Next, the thermoplastic resin composition 2 will be described. The thermoplastic resin composition 2 contains a thermoplastic resin. The thermoplastic resin is not limited as long as it is plasticized by applying shear rate or heat. For example, polyethylene, polypropylene, polystyrene, (meth) acrylic resin, polyamide, polycarbonate, polyacetal, thermoplastic polyester, heat Examples thereof include a plastic elastomer, polyphenylene sulfide, and a liquid crystal polymer. These resins may be used alone or in combination of two or more.

  Among the above thermoplastic resins, the extruder of the present invention can be suitably used for extrusion molding of a thermoplastic resin having a high melting point such as engineering plastics and high metal adhesion. Here, the thermoplastic resin having a high melting point is a thermoplastic resin having a melting point of 150 to 400 ° C., and specifically, polyamide, polyester, polyphenylene sulfide, and liquid crystalline polymer are preferable, and polyphenylene sulfide is particularly preferable.

  To the thermoplastic resin composition 2, other thermoplastic resins, various compounding agents, and the like can be added as necessary within a range not impairing the effects of the present invention. Examples of other resins include other polyolefin resins, polystyrene resins, and fluororesins. These other resins may be used alone or in combination of two or more. The compounding agents include stabilizers (antioxidants or antioxidants, ultraviolet absorbers, heat stabilizers, etc.), reinforcing agents such as glass fibers, antistatic agents, flame retardants, flame retardant aids, colorants ( Dyes, pigments, etc.), lubricants, plasticizers, lubricants, mold release agents, crystal nucleating agents, anti-dripping agents, crosslinking agents and the like.

  Among the other components described above, the use of a reinforcing agent is preferable. Examples of the reinforcing agent used by adding to the thermoplastic resin composition 2 include reinforcing agents having various shapes such as a fibrous shape, a powdery shape, a plate shape, a needle shape, a cloth shape, and a mat shape. In particular, fibrous reinforcing agents are preferable, and inorganic fibers or organic fibers such as glass fibers, ceramic fibers, carbon fibers, and metal-coated glass fibers are used. Further, the surface of these fibrous fillers may be surface-treated with a silane compound or the like. In these, an inorganic fiber, especially glass fiber are preferable from a heat resistant point.

  About the hopper 10, the cylinder 11, and the screw 12, what is used for a normal extruder can be used. The extruder may be an extruder having a single screw or a multi-screw or a combination of these. Further, when the extruder is a multi-screw extruder, the rotation direction of the screw may be different or the same in each axis, and may be a meshing type or a non-meshing type. Furthermore, the shape of the shaft may be a parallel type or a conical type. In addition, a tandem system in which screw extruders are combined in multiple stages may be used. The die plate of the present invention, the first gas spraying part, and the second gas spraying may be applied to these extruders. The thermoplastic resin composition can be extruded by incorporating the part.

<The manufacturing method of a thermoplastic resin composition pellet>
The thermoplastic resin composition 2 is put into the hopper 10. The thermoplastic resin composition 2 charged into the hopper 10 enters the cylinder 11. The thermoplastic resin composition 2 is conveyed in the direction toward the die plate 13 by passing between the screw 12 and the cylinder 11 by the rotation of the screw 12. The thermoplastic resin composition 2 is melted in the middle of conveyance in the direction of the die plate 13 and is sent to the die plate 13 in a molten state. The thermoplastic resin composition 2 sent to the die plate 13 is discharged through the discharge hole 130. The extrusion molding conditions (discharge amount, screw rotation speed, cylinder temperature, etc.) can be appropriately changed according to the type of material.

  Gas is blown from the first gas blowing section 14 to at least a part of the boundary line between the extruded strand-like material and the upper opening on the discharge surface A side of the discharge hole 130. In the present embodiment, gas is blown onto a portion including a boundary point between the upper end of the opening and the strand-like object. The spraying of the gas promotes the generation of the mains. Most of the generated spears fall due to the wind pressure of the gas.

  A gas is intermittently blown from the second gas blowing unit 15 to a boundary point between the strand-like material and the lower end of the opening existing on the discharge surface. Even if this gas blows and adheres to the vicinity of the lower end of the opening, it will fall before carbonization.

<Effect>
In this embodiment, the 1st gas spraying part 14 accelerates | stimulates the formation of the lump (henceforth Mayyan) of a thermoplastic resin composition. This main sticking sticks to the discharge surface A, and normally carbonizes and becomes black black. However, when extruding the molten thermoplastic resin composition 2 in a strand shape, gas is blown onto at least a part of the boundary line between the extruded strand-like material and the upper opening on the discharge surface A side of the discharge hole 130. As a result, before sticking to the discharge surface A or before sticking to the discharge surface A, the mains are blown off by the wind pressure of the gas. In this way, after promoting the formation of the black which becomes the base of the black, it is possible to suppress the carbon from being accumulated on the discharge surface A and being carbonized by quickly blowing off with the gas.
Further, as described above, the gas from the first gas spraying portion 14 is blown before Mayani is carbonized. As a result, there is no problem of foreign matter contamination even if the blown-out spider enters the pellets obtained by cutting the strand-like material.
In addition, mayani may be peeled off due to its own weight.

  Among the mess adhering to the ejection surface A, the mess adhering to the vicinity of the ejection hole 130 of the die plate 13 may fall due to friction with the strands being ejected and may be mixed into the strands being ejected. is there. In the present embodiment, as a result of the gas being blown as described above, the above-described fall due to the friction of the sealant adhering to the discharge hole 130 is promoted. For this reason, even if the above-mentioned friction is weak, Meani falls and mixes into the strand-like material. That is, there is a tendency that the main body drops in a short time after adhering to the discharge hole 130 and is mixed into the strand-like material. For this reason, even if Meyani mixes in the pellet obtained by cutting a strand-like thing, the problem of a foreign material mixing does not arise.

  In the present embodiment, the second gas blowing unit 15 is provided. By providing the second gas spraying portion 15, even if the main body accumulates in the vicinity of the lower end of the opening on the discharge surface A side, by blowing gas to the boundary point between the strand-shaped object and the lower end of the opening, Can be blown away early. Therefore, there is almost no possibility that the main body is carbonized on the discharge surface A. In addition, although the mayani stuck to the vicinity of the lower end of the opening on the discharge surface A side can be dropped by the gas sprayed from the first gas spraying part 14, it is more reliable by including the second gas spraying part 15. It can be dropped before discoloration.

In the present embodiment, the shortest distance (Δx) between the lower end P of the outer periphery of the opening on the discharge surface A and the outer periphery of the discharge surface A is 5 mm or less. For this reason, the contact area between the ejection surface A and the main surface is reduced. As a result, since the adhesive force between the mains and the discharge surface A is reduced, the mains can be easily dropped by blowing the gas from the second gas spraying part 15 in particular. Therefore, even if Meyani mixes in the product manufactured using the pellets obtained by cutting the strand-like material as a raw material, there is no problem of contamination.
In the present invention, the shortest distance is 2 mm or more. However, if the distance is less than 2 mm, problems such as insufficient strength of the mold occur. Therefore, even if it is less than 2 mm, the effect of the manufacturing method of this embodiment is exhibited.

  Moreover, said effect acquired by the gas sprayed from the 2nd gas spraying part 15 is fully show | played, even when spraying gas intermittently. Further, by intermittently blowing the gas, it is possible to shake the main body that is partially attached to the discharge surface A and suspended from the discharge surface A, and to drop the main body. Moreover, it can suppress that the die plate 13 is cooled by spraying gas intermittently. By suppressing the cooling of the die plate 13, problems such as unstable ejection can be suppressed.

In the present embodiment, a cutout portion is formed on the discharge surface A, and the cutout portion is formed below the position of the discharge hole 130 on the discharge surface A. And the gas sprayed from the 2nd gas spraying part 15 passes the space notched by formation of the notch part. That is, the second gas blowing unit 15 blows gas toward the outer periphery of the die plate 13 from an obliquely downward direction. Therefore, the gas blowing unit 15 is disposed below the die plate 13. In the present invention, the second gas spraying portion 15 may be disposed below the strand-like material. However, if the second gas spraying portion 15 is disposed at such a position, the strand shape is broken when the strand breaks. When an object falls on the 2nd gas spraying part 15 and the 2nd gas spraying part 15 is damaged, the problem which the sensor which notifies strand breakage does not operate may arise. In addition, this problem can prevent damage to a sensor etc. from fall of the broken strand-like thing by protecting the sensor which notifies a 2nd gas spraying part and strand breakage with a protection member.
Further, the second gas spraying portion 15 may be disposed at a position slightly away from the die plate 13 and the gas may be sprayed to the outer periphery of the die plate 13 without passing through the space formed by the notches. If this method is adopted, not only a strong wind pressure is required to drop the main sticking on the discharge surface, but also the gas injection range is widened to cool the die plate 13 and cause discharge unevenness. Etc. may occur.
Therefore, cooling of the die plate 13 can be suppressed by blowing the gas from the second gas blowing unit 15 to the outer periphery of the die plate 13 through the space formed by the notch, and particularly in the case of strand breakage. The above problems do not occur.

  As described above, in the present embodiment, the second gas spraying part 15 is disposed behind the discharge surface A, and the gas sprayed from the second gas spraying part 15 passes through the space cut out by the formation of the notch part. Gas passes. However, in the present invention, the second gas blowing portion 15 may be disposed in front of the discharge surface A. In this case, the protective member as described above may be required.

  In the present embodiment, the first gas blowing unit 14 blows gas from above the position of the discharge hole 130 on the discharge surface A. The first gas spraying unit 14 may spray gas from the right direction or the left direction to the strand-like material to be discharged. However, when a die plate having a plurality of discharge holes is used, the first gas spraying unit 14 is used for all the discharge holes. In order to blow the gas so as to achieve the effects of the invention, it is preferable to blow the gas from above.

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

<Equipment etc.>
Die plate 1: The die plate shown in FIG. 2, and the distance between the PQs is 2 mm. Moreover, the opening part of a discharge hole is circular with a diameter of 3 mm.
Die plate 2: A die plate similar to the die plate 1 except that the notch 131 is not provided (since it does not have a notch, the distance corresponding to the distance between PQs of the die plate 1 is 5 mm or more. Yes, specifically 50 mm.)
Extruder: A first gas spraying part and a second gas spraying part were arranged in a twin screw extruder (Tex65 manufactured by Nippon Steel Works) as shown in FIGS.
The shortest distance from the gas outlet of the first gas spraying part to the strand-like object is 5 cm.

<Comparative Example 1>
The die plate 2 is attached to the extruder. First, 0.45 parts by weight of aminosilane and 0.2 parts of stearic acid ester are added to 59.4 parts by weight of polyphenylene sulfide resin (viscosity 275 Pa · s, melting point 290 ° C.) on the raw material hopper. The mixture which mix | blended the mass part was supplied. Subsequently, 40 mass parts of glass fibers were supplied from the side feeder, and a polyphenylene sulfide resin composition reinforced with glass fibers was extruded. The molding conditions for extrusion were extrusion molding with an extrusion rate of 200 kg / hour and a screw rotation rate of 270 rpm to produce resin pellets with a thickness of 3 mm. The number of colored pellets was measured per 5 kg of resin pellets.

At the time of extrusion molding, normal temperature air is continuously blown from the first gas blowing section toward the boundary point between the strand-like material and the upper end of the opening on the discharge surface under the condition of a wind pressure of 2 kgf / cm ^2. It was.

  Extrusion molding was performed under the above conditions until the experiment numbers were from 0 to 240. The number of colored pellets in the experiment for each experiment number was counted. The measurement results are shown in FIG.

<Example 1>
Except that the die plate 2 was changed to the die plate 1 , the number of colored pellets was measured in the same manner as in Comparative Example 1. Extrusion molding was performed under the conditions of Example 1 up to the experiment numbers 241 to 350. The measurement results are shown in FIG.

<Example 2>
The number of pellets colored in the same manner as in Example 1 was measured except that the gas was blown so as to hit the boundary point between the strand-like material and the lower end of the opening from the second gas blowing portion.

  Extrusion molding was performed under the conditions of Example 2 above for experiment numbers 351 to 550. The measurement results are shown in FIG.

The second gas blowing unit was set so that air at normal temperature was blown intermittently at a wind pressure of 3 kgf / cm ² .

  According to the results of Example 1 and Comparative Example 1, by combining the shortest distance between the lower end of the outer periphery of the opening on the discharge surface and the outer periphery of the discharge surface and the blowing of gas from above, it depends on Meani It was confirmed that the number of colored pellets can be greatly reduced.

  From the results of Example 2 and Example 1, it was confirmed that the number of colored pellets can be suppressed to almost zero by adding gas blowing from below to Example 1 described above.

  Further, the resin pellets produced in Examples 1 and 2 were evaluated for general physical properties (specifically, melt viscosity, glass filling amount measurement by incineration of resin pellets and measurement of Ash, tensile strength, bending strength). However, it was equivalent to a resin pellet produced by a general method. That is, in the physical properties of the resin pellets obtained, no influence due to the use of the die plate of the present invention and no influence due to gas blowing were observed.

DESCRIPTION OF SYMBOLS 1 Extruder 10 Hopper 11 Cylinder 12 Screw 13 Die plate 130 Discharge hole 131 Notch part 14 1st gas spraying part 15 2nd gas spraying part 2 Thermoplastic resin composition

Claims (9)

A method for producing a thermoplastic resin composition pellet using an extruder,
When extruding the molten thermoplastic resin composition into a strand form from the discharge hole of the die plate provided in the extruder, the extruded strand-like material and the upper part of the opening on the discharge surface side of the discharge hole Spraying gas on at least part of the boundary,
Wherein the discharge face of the die plate, Ri shortest distance der 2mm or 5mm or less from the lower end of the opening of the discharge hole to the outer periphery of the die plate,
The method for producing a thermoplastic resin composition pellet , wherein an opening on the discharge surface side of the discharge hole exists on the discharge surface and does not have a protruding nozzle . At least a part on the boundary line is a part including a boundary point between the upper end of the opening and the strand-like object,
Furthermore, the manufacturing method of the thermoplastic resin composition pellet of Claim 1 which sprays gas also to one part including the boundary point of the lower end of the said opening, and the said strand-like thing. A notch is formed on the discharge surface of the die plate,
The notch is formed below the position of the opening on the ejection surface,
The thermoplastic resin composition pellets according to claim 2, wherein the gas blown to a part including a boundary point between the lower end of the opening and the strand-like material passes through the space cut out by the formation of the cutout portion. Method. A die plate having discharge holes for discharging a molten thermoplastic resin composition in a strand;
A first gas spraying unit that sprays gas onto the discharged strands, and an extruder,
In the discharge surface of the die plate, the shortest distance from the lower end of the opening of the discharge hole to the outer periphery of the die plate is 2 mm or more and 5 mm or less,
The gas spraying unit, when extruding the molten thermoplastic resin composition in a strand shape, gas is applied to at least a part of the boundary line between the extruded strand material and the upper opening on the discharge surface side of the discharge hole. Spray ,
The opening on the discharge surface side of the discharge hole is present on the discharge surface and does not have a protruding nozzle .   The extruder according to claim 4, wherein at least a part on the boundary line is a part including a boundary point between an upper end of the opening and the strand-like material.   The second gas spraying part which sprays gas toward the part including the boundary point of the lower end of the said opening and the said strand-like object from the downward direction rather than the position of the said opening in the said discharge surface is further provided. The extruder as described in. A notch is formed on the discharge surface,
The notch is formed below the position of the opening on the ejection surface,
The extruder according to claim 6, wherein the gas blown from the second gas blowing portion passes through the space cut out by the formation of the cutout portion. A die plate having discharge holes for discharging a molten thermoplastic resin composition into a strand shape,
Wherein the discharge face of the die plate, Ri shortest distance der 2mm or 5mm or less from the lower end of the opening of the discharge hole to the outer periphery of the die plate,
An opening on the discharge surface side of the discharge hole is a die plate that exists on the discharge surface and does not have a protruding nozzle . A notch is formed on the discharge surface,
The die plate according to claim 8, wherein the notch is formed below a position of the opening on the discharge surface.

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