JP2001089927A - Pack flow-straightening plate for molding thermoplastic polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably spin a high-quality/high-grade synthetic fiber having uniformity free from admixture of foreign matter in a pack for thermoplastic polymer extrusion molding by straightening a molten polymer at a part directly above a spinneret, uniforming a heat history of the molten polymer, controlling quality unevenness of the polymer and preventing abnormal retention to suppress thermal degradation of the polymer. SOLUTION: In a pack case for thermoplastic polymer extrusion molding, this pack flow-straightening plate for molding a thermoplastic polymer is obtained by providing a flow-straightening plate laid at the upstream side of a spinneret delivery part with a plurality of flow-straightening holes so as to satisfy conditions (1) L1 is L1=0.60×Ls (Ls is the distance of the straightening hole arranged at the outermost periphery from the center of the straightening plate), (2) La is 0<=La<L1, (3) Lb is L1<=Lb<=Ls and (4) Sb/Sa>1 (the totals of the opening areas of the straightening holes in which distances La and Lb from the center of the straightening plate are in the above range are Sa and Sb, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an extrusion molding of a thermoplastic polymer, and more particularly to a pack case used for melt spinning of a thermoplastic polymer. Despite having a simple structure, heat that can reduce abnormal stagnation of fluid in the pack case, reduce variations in quality between single yarns of discharged yarn, and reduce differences in fineness between yarns of multiple yarn take-up nozzles The present invention relates to a pack straightening plate for molding a plastic polymer.

[0002]

2. Description of the Related Art When a thermoplastic polymer having viscosity is melt-spun, the thermoplastic polymer in a molten state has a high viscosity of several hundred poise or more. The flow in the melt spinning pack and in the pipeline to the pack case is laminar. For this reason, the molten polymer flowing through the center of the pipe flows through the center of the pipe from beginning to end, and the molten polymer flowing near the pipe wall is near the end of the pipe wall, and is slower than the molten polymer at the center of the pipe due to the flow resistance from the pipe wall It tends to flow at a flow rate. This tendency also exists in the pack case, and the flow rate of the molten polymer passing through a portion closer to the outer wall than the center portion is slower, causing a stagnant portion.

On the other hand, since the pack case and the pipeline are heated to a high temperature from the outside, the molten polymer flowing at the center of the pipeline and the pack case and the molten polymer flowing at the tube wall and the outer wall side as described above. A difference in heat history occurs between them, and a molten polymer having a different melt viscosity and a different degree of polymerization is distributed on the cross section of the flow path. If the molten polymer having such a distribution is spun from the discharge section in that state, the spun yarn has a quality variation among the single yarns. In the case of spinning with a plurality of yarn take-up spinnerets, this may cause a difference in fineness between the yarns. Furthermore, when a stagnant portion is generated on the outer wall side where the flow velocity is reduced, the molten polymer in the stagnant portion is thermally degraded, and the thermally degraded product is mixed into the molten polymer and flows, and when spun out, the melted polymer This causes a problem that it becomes a foreign matter and induces thread breakage. Conventionally, as a countermeasure to solve such problems, a static mixer such as used for polymer piping is installed inside the melt spinning pack to uniformly melt polymers having different melt viscosities and degrees of polymerization. There has been proposed one in which the fibers are mixed into a state and then spun. However, this measure not only causes an increase in the cost of the melt-spinning pack because the static mixer is expensive, but also increases the pressure loss in the melt-spinning pack, thereby imposing an abnormal load on the metering pump. There is a problem that breakage is likely to occur, and the homogenization of the molten polymer immediately before spinning is insufficient.

[0004] As another method, Japanese Patent Application Laid-Open No. Hei 9-2811 proposes a method of increasing the flow rate of a molten polymer in an outer peripheral portion by providing an internal / external difference in pressure loss of a filter medium provided for the purpose of filtering a molten polymer. I have. However, this method has a problem that not only the method of installing the filter medium becomes complicated, but also the cost of processing or disposal of the filter medium increases. As another method, the inlet of the distribution hole of the perforated plate installed upstream of the discharge unit is made one, the outlet is divided into a plurality of holes, and the inner diameter becomes larger as the distribution hole communicates with the outer outlet. Japanese Patent Application Laid-Open No. 5-339808 proposes a method for reducing the quality distribution in the cross-sectional direction of the flow path of the molten polymer. However, this method has a problem that not only the processing cost of the distribution hole becomes expensive, but also that foreign matter tends to remain in the distribution hole even after the parts are washed.

[0005] As still another method, the entrance of the distribution hole of the perforated plate placed immediately before the discharge section is divided into the inside and outside, and the inside and outside of the two holes are joined at the exit, so that the cross section of the flow path of the molten polymer flows. Japanese Patent Application Laid-Open No. 9-09-1995
268418. However, this method also has a problem that not only the processing cost of the distribution hole becomes expensive, but also that foreign matter tends to remain in the distribution hole even after the parts are washed, and is insufficient as a method for preventing abnormal stagnation. Was.

[0006] In addition, the publications cited in the above-mentioned known examples do not specify at all about the improvement in the fineness difference between the yarns when a plurality of yarns are used.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and eliminate the need for incorporating a static mixer or the like in a pack case, and to manufacture or mix the same. Incorporation, easy cleaning after use, while reducing the variation in quality of the extruded product and the fineness difference between the yarns, while keeping the structure substantially the same as the conventional pack case, especially in the pack case It is an object of the present invention to provide a rectifying plate capable of suppressing occurrence of an abnormal stagnation portion.

[0008]

Means for Solving the Problems In a pack case for extrusion molding of a thermoplastic polymer, a flow straightening plate arranged on the upstream side of a mouthpiece discharge portion satisfies the following conditions (1) to (4). A pack flow straightening plate for thermoplastic polymer molding, wherein a plurality of flow straightening holes are installed in the pack. (1) L1: L1 = 0.60 × Ls Ls: Distance from the center of the rectifying plate of the rectifying hole arranged at the outermost periphery (2) La: 0 ≦ La <L1 (3) Lb: L1 ≦ Lb ≦ Ls ( 4) Sb / Sa> 1 (The sum of the opening areas of the rectifying holes in which the distances La and Lb from the center of the rectifying plate are in the above ranges is defined as Sa and Sb, respectively). By increasing the flow rate of the molten polymer flowing into the outer periphery, the flow velocity of the molten polymer flowing into the central portion and the flow rate of the molten polymer flowing into the outer peripheral side can be made uniform,
As a result, the average flow velocity increases, and the heat history of the fluid in the pack case can be made more uniform. Further, since the change in the flow direction vector of the molten polymer passing through the rectifying hole is small and the flow velocity is increased, it is possible to suppress occurrence of an abnormal stagnation portion immediately before the discharge portion. By the above effects, it is possible to spin and collect a yarn having a small variation in quality among single yarns and a small difference in fineness between the yarns when using a multiple yarn take-up die in a stable state with few yarn breaks. .

[0009]

1 and 2 show an example of an embodiment of a melt spinning pack provided with a current plate 3 of the present invention. 1 and 2, a pack case 1 has a spinneret 2 inserted and arranged at a lower portion thereof, and a straightening plate 3 of the present invention placed thereon.
Has been arranged. Further, a pressure-resistant plate 4 having an inflow hole 11 and a nonwoven fabric filter 5 are arranged thereon.

The pack shown in FIG.
Is filled with a filter layer 6 of filter sand, on which a block 8 is placed and closed by a lid 15. FIG.
In the pack shown in (1), a distribution plate 7 having one or more distribution holes 12 is inserted and arranged on a nonwoven fabric filter 5, and a block 8 is placed on the distribution plate 7 and closed by a lid 15. The spinneret 2 has a number of spinning holes 9, and the current plate 3 has a plurality of current holes 10. The block 8 is provided with an inflow hole 13.

In the illustrated embodiment, the rectifying hole 1 of the rectifying plate 3 is provided.
Straightening holes having the same diameter as 0 are arranged on concentric circles.
The configuration of the upper portion of the nonwoven fabric filter 5 may be filled with filter sand as shown in FIG. 1 or a component corresponding to the distribution plate 7 shown in FIG. 2 may be inserted. However, the filter sand is discarded after one use, but since the distribution plate can be reused by washing, a configuration in which the distribution plate is installed is preferable.

When the molten polymer pressurized to a high pressure is supplied to the melt-spinning pack having the structure shown in the drawing from the inlet 13 of the block 8, the molten polymer is once developed around the pack by the block 8 and then filtered. After passing through the layer 6 or the distribution plate 7, the unnecessary material is removed by the nonwoven fabric filter 5 and then passes through the inflow hole 11 of the pressure-resistant plate 4. Where 1
By being collected in one stream, the difference in heat history due to the difference in the passing locations that has occurred so far is reduced. Subsequently, the molten polymer flows into the central portion of the inflow surface of the current plate 3 and then flows into the current flow hole 10 while developing the inflow surface from the center to the outer periphery. The rectifying plate 3 distributes and rectifies the molten polymer into a plurality of streams through the rectifying holes 10, reduces the high pressure while giving a pressure loss through the rectifying holes 10, and discharges the molten polymer to the upstream side of the spinneret 2. Finally, the molten polymer is spun out from the spinning hole 9 of the spinneret 2 and formed into a yarn.

In such a melt-spinning pack, when the flow rate of the molten polymer flowing into the rectifying holes 10 on the outer periphery of the rectifying hole 10 becomes lower than that of the molten polymer flowing into the rectifying holes 10 at the center of the inflow surface of the rectifying plate 3, heat is generated. Differences in the histories or abnormal stagnation occur, resulting in irregularities such as unevenness in thread quality and thread breakage. However, the current plate 3 is designed so that the flow velocity at the outer peripheral portion is higher than that at the central portion, thereby improving the overall average flow velocity, and preventing occurrence of abnormal stagnation and occurrence of a heat history difference due to a difference in a passing place. Therefore, it is possible to avoid the occurrence of the above-mentioned malfunction factor. In the present invention, in order to improve the average flow velocity of the molten polymer directly above the die as described above and to prevent the occurrence of a difference in heat history, the distribution of the flow rate of the molten polymer passing through the current plate 3 is changed. It is important to design it so that it will flow positively to the outside.

That is, as shown in FIG. 3, when the distance from the center of the rectifying plate 3 to the rectifying hole provided at the outermost periphery is Ls, the rectifying hole 10 of the rectifying plate 3 is L1. Virtual circle C passing through the position (L1 = 0.60 × Ls)
With 1 as the boundary, it is necessary to make the sum of the opening areas of the rectification holes existing outside of the boundary larger than the sum of the opening areas of the rectification holes existing inside. However, when the rectifying plate is incorporated in the pack case, the outermost end of the rectifying hole provided on the outermost periphery thereof coincides with the outermost periphery of the internal space of the pack case, and is formed on the outermost peripheral portion. It is designed so that there is no stagnation area.

More specifically, the following conditions (1) to (4) are satisfied on the upstream side of the straightening plate disposed on the upstream side of the mouthpiece discharge portion in the thermoplastic polymer extrusion molding pack case. (1) L1: L1 = 0.60 × Ls Ls: Distance from the center of the rectifying plate of the rectifying hole arranged at the outermost periphery (2) La: 0 ≦ La <L1 (3) Lb: L1 ≦ Lb ≦ Ls ( 4) Sb / Sa> 1 (The sum of the opening areas of the rectifying holes in which the distances La and Lb from the center of the rectifying plate are in the above ranges is defined as Sa and Sb, respectively.) If a rectifying plate that does not satisfy this condition is used, rectification is performed. The flow rate of the molten polymer passing through the central portion of the plate becomes larger than the outer peripheral portion, and the flow of the central portion becomes more positive than the outer peripheral portion in the entire pack case due to the influence. The flow velocity of the molten polymer passing therethrough decreases, causing an abnormal stagnant portion or a difference in heat history with the molten polymer passing through the central portion. The thermally degraded material generated by the thermal degradation of the molten polymer in the abnormal stagnation section flows out during spinning, or the difference in heat history due to the difference in the location where it passes becomes a defect of the spun yarn, causing spun yarn breakage. This may cause breakage of the drawn yarn.

More preferably, the above conditions (1) to
At the same time as (4), the following conditions (5) to (8), or conditions (9) to (12), or conditions (1) to (12) are simultaneously satisfied. (5) L2: L2 = 0.84 × Ls (6) Lc: L1 <Lc <L2 (7) Ld: L2 ≦ Ld ≦ Ls (8) Sd / Sc ≧ 1 (Distances Lc and Ld from the center of the current plate Are the sums of the opening areas of the rectifying holes within the above range, respectively, Sc and Sd.) (9) L3: L3 = 0.34 × Ls (10) Le: 0 ≦ Le <L3 (11) Lf: L3 ≦ Lf <L1 (12) Sf / Se ≧ 1 (The sum of the opening areas of the rectifying holes in which the distances Le and Lf from the center of the rectifying plate are within the above ranges is defined as Se and Sf, respectively.) The use of a plate further increases the flow velocity in the outer peripheral portion, and as a result, not only improves the average flow velocity, but also prevents occurrence of abnormal stagnation and occurrence of a difference in heat history.

More preferably, the taper angle θ is continuously provided from the center of the inflow surface of the current plate to the outer periphery.

Thus, the change in the direction vector of the flow of the molten polymer passing through the outer peripheral portion can be reduced, so that the rectifying effect is further enhanced and occurrence of abnormal stagnation can be prevented.

By the effect of the current plate of the present invention, the flow rate of the molten polymer immediately above the die is made uniform, and the occurrence of abnormal stagnation is also prevented by the effect. can do.

[0020]

EXAMPLES Each evaluation item was defined as follows. Yarn breakage occurrence rate Spinning yarn breakage rate (times / t) = Number of yarn breaks generated during spinning (times) / production amount (t) Stretched yarn breakage rate (%) = Number of yarn breakage occurrence weights / Total number of working weights x
100 Difference in yarn fineness between yarns Difference in fineness between yarns (%) = (absolute value of difference in fineness between two yarns) / Target fineness × 100 Mixing degree ○○ Dense and uniform dispersion ○: Uniformly dispersed △ Distributed to outer periphery 部Deviation toward the center ×: Concentration at the center Taper angle θ (deg) tan θ = (Li-Lo) / Li-o Li: Depth of the rectification hole arranged at the innermost periphery Lo: Rectification arranged at the outermost periphery Hole depth Li-o: distance between rectifying holes arranged at the innermost and outermost circumference Examples 1 to 5 and Comparative Examples 1 to 2 In the pack for melt spinning illustrated in FIG. A melt spinning pack was prepared as shown in Table 1 with the hole conditions. A spinneret having 18 spin holes (36 holes in total) perforated into the melt-spinning pack equally, and 50 denier, 18-filament polyester yarns are spun into two yarns from one pack at a spinning speed of 3000 m / m. The sample was taken in min., the yarn breakage occurrence rate was measured, and the difference in fineness between two yarns taken from one pack was measured. The polyester yarn was drawn at a drawing speed of 1300 m / min by a drawing machine, and the rate of occurrence of yarn breakage at that time was measured.

Further, the other one pack of each level is loaded with the same amount of colored chips from the inflow holes of the pack and attached to a spinning machine. The same polyester molten polymer is poured into the pack and discharged from the spinneret. The distribution of the colored portions of the polymer was visually evaluated. The results are shown in Table 1.

[0022]

[Table 1]

[0023]

As described above, the pack straightening plate for thermoplastic polymer molding of the present invention has a difference between the center and the outer periphery in the total opening area of the straightening holes of the straightening plate without using a static mixer. Designed to allow the thermoplastic polymer to flow positively around the outer periphery, it is possible to reduce the difference between the inside and outside of the fluid history just above the mouthpiece and at the same time suppress the occurrence of abnormal stagnation due to insufficient flow velocity on the outer periphery. it can. Therefore, flow uniformization and abnormal stagnation prevention can be achieved by the rectifying plate that can reduce the processing cost while having a structure that is almost the same as the conventional parts.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a pack for melt spinning on which a current plate according to the present invention is arranged.

FIG. 2 is a longitudinal sectional view illustrating a pack for melt spinning on which a current plate according to the present invention is arranged.

FIG. 3 is a plan view illustrating an embodiment of the current plate of the present invention.

FIG. 4 is a cross-sectional view of X of FIG. 3 illustrating an embodiment of the current plate of the present invention;
FIG.

[Explanation of symbols]

 1: Pack case 2: Spinneret 3: Rectifier plate 4: Pressure plate 5: Non-woven fabric filter 6: Filter layer of filter sand 7: Distribution plate 8: Block 9: Spinning hole 10: Rectification hole 11: Inflow hole 12: Distribution hole 13: Inlet hole 14: Spacer 15: Lid

Claims (4)

[Claims] In a pack case for extrusion molding of a thermoplastic polymer, a plurality of rectifying plates are provided on a rectifying plate arranged on an upstream side of a die discharge portion so as to satisfy the following conditions (1) to (4). A pack straightening plate for forming a thermoplastic polymer, characterized by having holes. (1) L1: L1 = 0.60 × Ls Ls: Distance from the center of the rectifying plate of the rectifying hole arranged at the outermost periphery (2) La: 0 ≦ La <L1 (3) Lb: L1 ≦ Lb ≦ Ls ( 4) Sb / Sa> 1 (the sums of the opening areas of the rectifying holes in which the distances La and Lb from the rectifying plate center are within the above ranges are defined as Sa and Sb, respectively). 2. The pack straightening plate for molding a thermoplastic polymer according to claim 1, wherein the straightening holes are provided so as to satisfy the following conditions (5) to (8). (5) L2: L2 = 0.84 × Ls (6) Lc: L1 <Lc <L2 (7) Ld: L2 ≦ Ld ≦ Ls (8) Sd / Sc ≧ 1 (Distances Lc and Ld from the center of the current plate Are the sums of the opening areas of the rectifying holes within the above-mentioned ranges are Sc and Sd, respectively.) 3. The pack flow straightening plate for molding a thermoplastic polymer according to claim 1, wherein the flow straightening holes are provided so as to satisfy the following conditions (9) to (12). (9) L3: L3 = 0.34 × Ls (10) Le: 0 ≦ Le <L3 (11) Lf: L3 ≦ Lf <L1 (12) Sf / Se ≧ 1 (Distances Le, Lf from the center of the current plate Are the total sum of the opening areas of the rectifying holes within the above-mentioned range, respectively, as Se and Sf.) 4. An inflow surface of a current plate, wherein a taper angle is continuously provided from a central portion to an outer periphery.
4. The pack straightening plate for molding a thermoplastic polymer according to any one of items 2 and 3.