JP2015081399A - Filter and spinning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a metallic short fiber from falling off while keeping the thickness of a filter as small as possible in the filter made by laminating two kinds of metallic short fiber filters; and to prevent the filter from being mounted in an opposite direction by mistake.SOLUTION: A filter 44 includes: a first filter layer 51 made by sintering first metallic short fibers 50a having a polygonal cross section; a second filter layer 52 laminated on the first filter layer 51 and made by sintering second metallic short fibers 50b having a circular cross section; and a third filter layer 53 laminated on the second filter layer 52. The third filter layer 53 is not laminated on the first filter layer 51, and the surface of the first filter layer 51 opposite to the second filter layer 52 is exposed.

Description

  The present invention relates to a filter for filtering molten polymer and a spinning method for spinning a molten polymer filtered by a filter from a spinneret.

  Conventionally, a spinning pack for spinning a molten polymer from a spinneret is known. A typical spin pack has a filter for filtering molten polymer therein.

  The spinning pack of Patent Document 1 has a metal wire filter therein. The metal wire filter includes a sintered metal fiber filter and a wire mesh that is superimposed on both surfaces of the sintered metal fiber filter. Patent Document 1 describes that the wire mesh does not necessarily need to be disposed on both sides of the sintered metal fiber filter, and may be provided on at least one surface.

  In addition, although not described clearly in Patent Document 1, a conventional metal fiber sintered filter that has been used in the past sintered metal short fibers obtained by stretching a wire-like metal. The short metal fibers have a circular cross-sectional shape (hereinafter referred to as “circular cross-section short metal fiber filter”).

  Moreover, the spinning pack of patent document 2 has a metal wire filter, the sintered filter arrange | positioned above this metal wire filter, and the filter medium with which the sintered filter was filled. The sintered filter is a filter formed by sintering short metal fibers having a polygonal cross section. Such a filter is referred to as a “polygonal cross-section metal short fiber filter” with respect to the aforementioned “circular cross-section metal short fiber filter”. The short metal fiber having a polygonal cross section is manufactured by a chatter vibration cutting method. In addition, the polygon cross-section metal short fiber filter is provided in order to subdivide the gel-like part in molten polymer with a filter medium.

Japanese Patent No. 3365000 JP 2005-256197 A

  By the way, the inventors of the present application baked two types of metal fibers, which are different from each other in the type of short metal fibers, that is, a conventional circular section metal short fiber filter and a polygonal cross section metal short fiber filter as disclosed in Patent Document 2. We are considering the use of laminated filter layers. As a result, the gel-like portion in the molten polymer is subdivided by the polygonal cross-section metal short fiber filter, and foreign substances contained in the melt polymer are surely secured by two types of filter layers having different cross-sections of the metal short fiber. Can be collected.

  However, if the two types of filter layers are simply overlapped, the metal short fibers are easily dropped from the exposed surface of the filter layer and easily mixed into the molten polymer. In this regard, in the configuration in which the metal mesh is disposed on both sides of the metal short fiber filter layer as in Patent Document 1, the metal short fibers are prevented from falling off from the metal short fiber filter layer. However, when the two types of short metal fiber filter layers are superposed, the thickness of the filter is increased, and further, when the wire mesh is disposed on both sides, the thickness of the filter is further increased. As the thickness of the filter increases, the residence time of the molten polymer in the spin pack is increased correspondingly, and thermal degradation of the molten polymer is likely to occur.

  If the same metal mesh is provided on both sides of the two types of short metal fiber filter layers, it is very difficult to determine which side of the filter is the side on which the short metal fiber filter layer is disposed. Therefore, there is a possibility that the spinning pack is erroneously attached in the reverse direction. Since the two types of short metal fiber filter layers have different required functions, if they are attached in opposite directions, the desired filtration performance cannot be exhibited.

  One object of the present invention is to prevent the short metal fibers from falling off while keeping the filter thickness as small as possible in a filter in which two types of short metal fiber filters are laminated. Another object of the present invention is to prevent the filter from being attached in the reverse direction.

Means for Solving the Problems and Effects of the Invention

The filter of the first invention is a filter for filtering a molten polymer spun from a spinneret before spinning,
A first filter layer formed by sintering first metal short fibers having a polygonal cross section, and a second filter layer formed by sintering second metal short fibers stacked on the first filter layer and having a circular cross section. And a third filter layer laminated on the second filter layer, the third filter layer not laminated on the first filter layer, and the second filter of the first filter layer The surface opposite to the layer is exposed.

  According to the present invention, the gel-like portion in the molten polymer is subdivided by the first filter layer which is a polygonal cross-section metal short fiber filter. Moreover, the 2nd filter layer which is a circular cross-section metal short fiber filter is laminated | stacked on the 1st filter layer, and a foreign material is reliably collected by these two filter layers. In the present invention, the “circular cross section” is not limited to a perfect circular cross-sectional shape, and includes a cross section that is slightly flat with respect to a perfect circle and has an elliptical cross-sectional shape.

  In addition, the inventors of the present application have found that there is a difference in the ease of dropping of the metal short fibers between the first filter layer and the second filter layer having different types of metal short fibers. Specifically, it has been found that the first metal short fibers of the first filter layer are less likely to drop out than the second metal short fibers of the second filter layer. The following reasons are conceivable. Since the first metal short fibers have a polygonal cross section, the first metal short fibers can be in surface contact with each other in the first filter layer, and the contact area between the fibers is increased. On the other hand, since the second metal short fibers have a circular cross section, the second metal short fibers can contact each other only by point contact in the second filter layer. That is, since the surface contact cannot be achieved, the contact area between the fibers is small, and the fibers can be bonded only in a small area during sintering, and thus a strong bonding force cannot be obtained. From the above, it is presumed that the first metal short fiber having a polygonal cross section is less likely to drop out than the second metal short fiber having a circular cross section.

  In view of the above points, in the present invention, the third filter layer is laminated on the second filter layer in which the metal short fibers are likely to fall off. As a result, the second filter layer is sandwiched between the first filter layer and the third filter layer, and the second metal short fibers are prevented from falling off the second filter layer. On the other hand, the third filter layer is not laminated on the first filter layer, and the surface of the first filter layer opposite to the second filter layer is exposed. Since the first short metal fibers are unlikely to fall off the first filter layer, there is no problem even if the third filter layer is not provided.

  As described above, since the third filter layer is provided only on the second filter layer, it is possible to prevent the short metal fibers from falling off while keeping the thickness of the entire filter small. Further, since the first filter layer is not covered with the third filter layer, it can be easily recognized which surface of the filter is the surface on the first filter layer side. Therefore, when the filter is assembled to the spin pack, the filter is prevented from being attached in the reverse direction.

  The filter of the second invention is characterized in that, in the first invention, the filtration particle size of the second filter layer is smaller than the filtration particle size of the first filter layer.

  According to the present invention, small foreign matters in the molten polymer that cannot be captured by the first filter layer can be reliably removed by the second filter layer.

  According to a third aspect of the present invention, in the second aspect, the fiber diameter of the second short metal fibers of the second filter layer is a conversion in a circular cross section of the first short metal fibers of the first filter layer. It is smaller than the diameter.

  In the present invention, the “equivalent diameter in the circular cross section of the first short metal fibers” refers to the diameter of a circle having a cross-sectional area equal to that of the first short metal fibers having a polygonal cross section. In the present invention, since the second short metal fibers are thinner than the first short metal fibers, the second filter layer made of the second short metal fibers is a filter layer having a smaller filtration particle size than the first filter layer. Is possible.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the third filter layer is formed of a wire mesh, and the number of meshes of the third filter layer is 30 to 100 mesh. It is characterized by this.

  In the present invention, the third filter layer is formed of a wire mesh, and the number of meshes is 30 to 100 mesh, which has sufficient rigidity. Therefore, the third filter layer also serves to reinforce the first filter layer and the second filter layer. Therefore, deformation of the filter due to the pressure of the molten polymer is suppressed.

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the first filter layer, the second filter layer, and the third filter layer are integrated. It is what.

  In the present invention, since the three filter layers are integrated, operations such as attachment of the filter during assembly of the spin pack and removal of the filter during disassembly of the spin pack are facilitated.

The spinning method of the sixth invention is a spinning method of spinning the molten polymer filtered by the filter of any one of the first to fifth inventions from the spinneret.
The filtration particle size of the first filter layer is 20 to 50 μm, the filtration particle size of the second filter layer is 10 to 30 μm, and the spinning amount of the molten polymer from the spinneret is 80 g / min or less. To do.

  If you use a filter with a small filtration particle size and produce thick yarn (increase the amount of molten polymer spun), the pressure in the spin pack will become too high, and the filter will clog because it will clog early. The life of the pack is shortened. In the present invention, when the filtration particle size of the first filter layer is 20 to 50 μm and the filtration particle size of the second filter layer is 10 to 30 μm, the spinning amount is set to 80 g / min or less.

  The spinning method according to a seventh aspect is the method according to the sixth aspect, wherein the first filter layer has a filtration particle size of 20 to 30 μm, the second filter layer has a filtration particle size of 10 to 20 μm, and the molten polymer from the spinneret. The amount of spinning is set to 40 g / min or less.

  When the filter particle size of the filter is considerably small, that is, when the filter particle size of the first filter layer is 20 to 30 μm and the filter particle size of the second filter layer is 10 to 20 μm, the spinning amount is 40 g / min or less. .

The spinning method of the eighth invention is a spinning method of spinning the molten polymer filtered by the filter of any one of the first to fifth inventions from the spinneret,
The filtration particle size of the first filter layer is 50 to 80 μm, the filtration particle size of the second filter layer is 20 to 40 μm, and the spinning amount of the molten polymer from the spinneret is 50 g / min or more. To do.

  Contrary to the sixth aspect of the invention, when a fine thread is produced using a filter having a large filtration particle size (reducing the amount of melt polymer spun), the pressure in the spin pack becomes too low. The spinning of the polymer becomes unstable. In the present invention, when the filtration particle size of the first filter layer is 50 to 80 μm and the filtration particle size of the second filter layer is 20 to 40 μm, the spinning amount is set to 50 g / min or more.

1 is a schematic configuration diagram of a melt spinning apparatus and a spinning take-up machine according to the present embodiment. It is sectional drawing of the pack mounting part of a spinning pack and a heating box. It is sectional drawing of a filter. (A) is a rough expanded sectional view of the A section of FIG. 3, (b) is a schematic expanded sectional view of the B section of FIG. It is sectional drawing of the spinning pack which concerns on a modified form, and a pack mounting part. It is sectional drawing of the spinning pack which concerns on another modified form, and a pack mounting part.

  Next, an embodiment of the present invention will be described. FIG. 1 is a schematic configuration diagram of a melt spinning apparatus 1 and a spinning take-up machine 2 that winds a yarn Y spun from the melt spinning apparatus 1 according to the present embodiment. The vertical direction in FIG. 1 is defined as the vertical direction of the melt spinning apparatus 1 and the spinning take-up machine 2. First, schematic configurations of the melt spinning apparatus 1 and the spinning take-up machine 2 will be described.

  The melt spinning apparatus 1 includes a heating box 3 and a plurality of spinning packs 4 that are detachably attached to the heating box 3. The plurality of spin packs 4 are arranged side by side in the direction perpendicular to the paper surface of FIG. From each spinning pack 4, a yarn Y composed of a plurality of filaments f is spun downward. The configuration of the melt spinning apparatus 1 including the spinning pack 4 will be described in detail later.

  The spinning take-up machine 2 includes an oil guide 10, a guide roller 11, five godet rollers 12 to 16, a guide roller 17, and a winding device 18. The plurality of yarns Y spun downward from the plurality of spinning packs 4 of the melt spinning apparatus 1 are fed with the oil agent by the oil agent guide 10 and then sent to the five godet rollers 12 to 16 by the guide roller 11.

  Each of the five godet rollers 12 to 16 is a heating roller having a heater therein, and is housed in a heat insulation box 19. The lower three godet rollers 12 to 14 are heating rollers for preheating the plurality of yarns Y before drawing. On the other hand, the upper two godet rollers 15 and 16 are heating rollers for heat-setting a plurality of stretched yarns Y. Further, the yarn feeding speeds of the two godet rollers 15 and 16 located on the downstream side in the yarn feeding direction are faster than the three godet rollers 12 to 14 located on the upstream side in the yarn feeding direction.

  The plurality of yarns Y introduced into the heat insulation box 19 are first preheated to a temperature that can be stretched while being fed by the lower three godet rollers 12 to 14, and then the plurality of preheated yarns Y are The two godet rollers 14 and 15 are stretched by a difference in yarn feed speed. Further, the plurality of yarns Y are heated to a higher temperature while being fed by the upper two godet rollers 15 and 16, and the stretched state is heat set. The plurality of yarns Y drawn by the five godet rollers 12 to 16 in the heat insulation box 19 are sent to the winding device 18 by the guide roller 17.

  The winding device 18 includes a bobbin holder 20 and a contact roller 21. The bobbin holder 20 has a long shape extending in the direction perpendicular to the plane of FIG. 1 and is driven to rotate by a motor (not shown). A plurality of bobbins 22 are attached to the bobbin holder 20 along the axial direction. The winding device 18 rotates the bobbin holder 20 to simultaneously wind the plurality of yarns Y sent by the guide roller 17 around the plurality of bobbins 22 to form a plurality of winding packages 23. The contact roller 21 contacts the surface of the plurality of winding packages 23 and applies a predetermined contact pressure to adjust the shape of the winding package 23.

  Next, the melt spinning apparatus 1 will be described in detail. FIG. 2 is a cross-sectional view of the spinning pack 4 and the pack mounting portion 31 of the heating box 3. In FIG. 2, only the pack mounting portion 31 of the heating box 3 is indicated by a solid line, and other portions are indicated by a two-dot chain line.

  First, the heating box 3 to which the spinning pack 4 is mounted will be described. The heating box 3 supplies molten polymer to the spinning pack. In this embodiment, a molten polymer such as polyester having a viscosity of 300 Pa · s or less is used to produce a yarn for clothing. The inside of the heating box 3 is filled with a heat medium vapor supplied from a boiler (not shown) and is kept at a high temperature (for example, about 300 ° C.). Thereby, the molten polymer which passes the inside of the heating box 3 is maintained within a certain appropriate temperature range. The heating box 3 has a plurality of storage recesses 30 on its lower surface. Each storage recess 30 has a cylindrical hole shape, and a pack mounting portion 31 is attached to the ceiling surface of each storage recess 30.

  The pack mounting portion 31 is a member having a substantially T-shaped cross section including a disk-shaped fixing portion 32 and a shaft portion 33 extending directly from a substantially central portion of the lower surface of the fixing portion 32. In the pack mounting portion 31, a polymer flow path 34 penetrating vertically through the pack mounting portion 31 is formed from the fixed portion 32 to the lower end of the shaft portion 33. The fixing part 32 is fixed to the ceiling surface of the housing recess 30 of the heating box 3 by a bolt (not shown). At this time, the upper end of the polymer flow path 34 is connected to a polymer flow path (not shown) in the heating box 3. Further, a male screw portion 33 a is formed on the outer surface of the shaft portion 33.

  Next, the spinning pack 4 will be described. The spinning pack 4 is inserted into the storage recess 30 of the heating box 3 and is detachably mounted on the pack mounting portion 31. The spinning pack 4 includes a pack main body 40, a case member 41, and a lock ring 42. The pack main body 40 has a substantially cylindrical shape. The case member 41 has a cylindrical shape, and the pack main body 40 is accommodated in the case member 41. At this time, a plurality of nozzles 54 provided on the lower surface of the pack body 40 are exposed at the lower end opening 41 a of the case member 41. The lock ring 42 is attached to the upper part of the case member 41, and prevents the pack main body 40 from falling off (detaching) from the case member 41.

  The pack body 40 will be described. The pack body 40 includes a polymer inflow member 43, a filter 44, and a spinneret 45.

  A bottomed cylindrical portion 46 is formed on the top of the polymer inflow member 43. A female screw portion 46 a is formed on the inner peripheral surface of the cylindrical portion 46. Further, an introduction portion 47 for introducing a molten polymer into the spinning pack 4 is formed at the bottom of the cylindrical portion 46. When the spinning pack 4 is rotated and inserted into the storage recess 30 of the heating box 3, the male thread portion 33 a of the shaft portion 33 of the pack mounting portion 31 and the female thread portion 46 a of the cylindrical portion 46 of the polymer inflow member 43 are screwed together. Thus, the spinning pack 4 is mounted on the pack mounting portion 31. The pack mounting portion 31 is provided with a regulating member 35 for preventing the spinning pack 4 from rotating more than a predetermined angle with respect to the pack mounting portion 31. When the spinning pack 4 is mounted on the pack mounting portion 31, the lower end surface of the shaft portion 33 of the pack mounting portion 31 is pressed against the bottom of the cylindrical portion 46 of the polymer inflow member 43, so that the polymer flow on the pack mounting portion 31 side is reduced. The passage 34 and the introduction portion 47 of the polymer inflow member 43 are connected. A packing 48 is provided between the shaft portion 33 of the pack mounting portion 31 and the cylindrical portion 46 of the polymer inflow member 43 to seal the connecting portion between the polymer flow path 34 and the introduction portion.

  A polymer supply hole 43 a communicating with the introduction part 47 and a buffer space 49 directly connected to the introduction part 47 through the polymer supply hole 43 a are formed in the lower part of the polymer inflow member 43. The buffer space 49 has a conical hole shape that expands in the horizontal direction as it goes downward from the communicating portion with the introduction portion 47. The buffer space 49 is filled with the molten polymer introduced from the upper introduction portion 47 through the polymer supply hole 43a.

  The filter 44 is disposed in a lower space of the buffer space 49. More specifically, the filter 44 is disposed at the lower end position of the buffer space 49. The filter 44 includes a first filter layer 51, a second filter layer 52, and a third filter layer 53, which are stacked in order from the top. The configuration of the filter 44 will be described in detail later.

  The spinneret 45 is disposed below the filter 44 and in contact with the lower surface of the filter 44. That is, there is no other member between the filter 44 and the spinneret 45, and the molten polymer that has passed through the filter 44 flows into the spinneret 45 as it is. The spinneret 45 has a plurality of nozzles 54 that respectively spin the molten polymer that has passed through the filter 44. All the nozzles 54 of the spinneret 45 overlap with a buffer space 49 located immediately above the nozzle 54 in the vertical direction. In other words, the buffer space 49 is formed to extend in the surface direction of the filter 44 across all the nozzles 54 of the spinneret 45.

  The spinning pack 4 described above has a very simple configuration in which the introduction portion 47, the buffer space 49, the filter 44, and the spinneret 45 are arranged in series in this order.

  Next, the configuration of the filter 44 will be described in detail. FIG. 3 is a cross-sectional view of the filter 44. As shown in FIG. 3, FIG. 4A is a schematic enlarged cross-sectional view of the first filter layer 51 at a portion A in FIG. 3. FIG. 4B is a schematic enlarged cross-sectional view of the second filter layer 52 at a portion B in FIG.

  The first filter layer 51 is a layer formed by sintering a large number of first metal short fibers 50a. More specifically, as shown in FIG. 4A, the first short metal fibers 50a constituting the first filter layer 51 have a polygonal cross section (for example, a triangular cross section) with an acute corner. As a metal material used as the raw material of the 1st filter layer 51, materials with high corrosion resistance, such as stainless steel, are preferable. The first short metal fibers 50a having the polygonal cross section can be generally manufactured by a chatter vibration cutting method. In the chatter vibration cutting method, while rotating a metal material as a raw material, a self-excited vibration (chatter vibration) is intentionally generated in the cutting tool to process the metal material, thereby producing ultrafine short fibers. The first metal short fiber 50a manufactured by this method has an acute polygonal cross section due to the chatter vibration. The first metal short fiber 50a has a fiber length of 1.0 to 3.0 mm, a diameter (in terms of a circular cross section) of 30 to 100 μm, and an aspect ratio of 10 to 100.

  The porosity of the first filter layer 51 is 60 to 80%, which is almost the same as the porosity of metal powder often used in conventional spinning packs. Moreover, since the fiber diameter of the 1st metal short fiber 50a is comparatively large as mentioned above, it is difficult to make the filtration particle size of the 1st filter layer 51 small, for example, is 20 micrometers or more. The filtration particle size (also referred to as filtration accuracy) is an index indicating how large foreign matter can be removed by the filter, and the filtration particle size of 20 μm means that 95% or more of foreign matters having a size of 20 μm or more are removed. It shows that.

  By the way, a part of the molten polymer supplied to the spinning pack 4 may be gelled. In this respect, since the first filter layer 51 is a layer formed by sintering the short metal fibers 50 having a polygonal cross section, the gel-like portion is contained in the molten polymer supplied from the heating box 3 to the spinning pack 4. Even if there is, the gelled portion is divided and subdivided so as to be chopped by the sharp corners of a large number of short metal fibers 50 when passing through the first filter layer 51. The granular filter medium used in the conventional spinning pack also has a function of subdividing the gel-like portion in the molten polymer, but omitting the granular filter medium by providing the first filter layer 51 instead of the conventional granular filter medium. It becomes possible to do.

  The second filter layer 52 is also a layer formed by sintering a large number of second metal short fibers 50b. In addition, the 2nd metal short fiber 50b which comprises the 2nd filter layer 52 is obtained by extending a wire-like metal. Therefore, as shown in FIG. 4B, the second short metal fibers 50b have a substantially circular cross-sectional shape in a cross section orthogonal to the fiber length. Here, the “circular cross section” includes not only a perfect circular shape but also a cross sectional shape close to an ellipse. The second filter layer 52 is also preferably formed of a material having high corrosion resistance such as stainless steel, like the first filter layer 51. The fiber length of the second short metal fibers 50b is 20 to 30 mm, and the fiber diameter is 10 to 30 μm.

  The porosity of the second filter layer 52 is the same as that of the first filter layer 51, and is, for example, 60 to 80%. The second filter layer 52 is a layer having a smaller filtration particle size than the first filter layer 51. Since the second metal short fibers 50b constituting the second filter layer 52 have a smaller fiber diameter than the first metal short fibers 50a, the filtration particle size of the second filter layer 52 can be reduced. Although the filtration particle size of the 2nd filter layer 52 is based also on the filtration particle size of the 1st filter layer 51 used together with this, it is 10-40 micrometers, for example. The second filter layer 52 removes small foreign matters that could not be collected by the first filter layer 51 having a relatively large filtration particle size. That is, the second filter layer 52 is a filter layer that performs “final microfiltration”.

  The third filter layer 53 is a wire mesh filter. The type of wire mesh is not particularly limited, and a general plain weave wire mesh or other wire meshes such as twill weave, plain tatami mat, twill tatami weave, and the like can also be used. One of the purposes for which the third filter layer 53 formed of a wire mesh is provided is to reinforce the first filter layer 51 and the second filter layer 52. The rigidity of the second filter layer 52 formed by sintering the short metal fibers 50b is low. Therefore, the second filter layer 52 is easily deformed by the pressure of the molten polymer. For example, the pressure of the molten polymer may cause the filter 44 to be locally deformed at the position of the hole connected to the nozzle 54 on the upper surface of the spinneret 45 and enter the hole.

  If the mesh of the metal mesh constituting the third filter layer 53 is too fine, the rigidity of the third filter layer 53 is low and a sufficient reinforcing effect cannot be obtained. Therefore, the number of meshes per inch (hereinafter also simply referred to as the number of meshes) indicating the fineness of the third filter layer 53 is 30 to 100 meshes. Since the third filter layer 53 is laminated on the first filter layer 51 and the second filter layer 52, the rigidity of the filter 44 is increased, and deformation of the filter 44 due to the pressure of the molten polymer is suppressed.

  Another major purpose for providing the third filter layer 53 is to prevent the second short metal fibers 50b from falling off the second filter layer 52. The first filter layer 51 and the second filter layer 52, which are different types of short metal fibers, are different in the ease of dropping of the short metal fibers. Specifically, the first short metal fibers 50 a of the first filter layer 51 are less likely to drop out than the second short metal fibers 50 b of the second filter layer 52. The reason is estimated as follows:

  Since the first metal short fibers 50a have a polygonal cross section, the first metal short fibers 50a can be in surface contact with each other in the first filter layer 51, and the contact area between the fibers is increased. On the other hand, since the second short metal fibers 50b have a circular cross section, the second short metal fibers 50b can contact each other only by point contact in the second filter layer 52. That is, since the surface contact cannot be achieved, the contact area between the fibers is reduced, and the fibers can be bonded only in a small area during sintering, and thus a strong bonding force cannot be obtained.

  Moreover, since the 1st metal short fiber 50a manufactured by the chatter vibration cutting method has many micro unevenness | corrugations in the fiber surface, it becomes easy for fibers to get entangled and it becomes difficult to slip. On the other hand, the second metal short fibers 50b obtained by stretching the wire are not easily entangled and slippery because the fiber surface is smooth. For the above reasons, the first metal short fibers 50a having a polygonal cross section are less likely to fall off than the second metal short fibers 50b having a circular cross section.

  From the above, in the present embodiment, the third filter layer 53 is laminated on the second filter layer 52 where the metal short fibers are likely to fall off. As a result, the second filter layer 52 is sandwiched between the first filter layer 51 and the third filter layer 53, and the second metal short fibers 50b are prevented from falling off from the second filter layer 52. On the other hand, the third filter layer 53 is not laminated on the first filter layer 51, and the surface of the first filter layer 51 opposite to the second filter layer 52 is exposed. Since the first metal short fibers 50a do not easily fall off from the first filter layer 51, there is no problem even if the third filter layer 53 is not provided.

  As described above, since the third filter layer 53 is provided only on the second filter layer 52, it is possible to prevent the metal short fibers from falling off while suppressing the thickness of the entire filter 44 to be small. By keeping the thickness of the filter 44 small, the residence time of the molten polymer in the spin pack 4 can be shortened accordingly.

  Specifically, the thickness of the filter 44 is 5 mm or less, preferably 3 mm or less. However, if the first filter layer 51 is too thin, it is difficult to subdivide the gel-like portion in the molten polymer sufficiently small. Therefore, the thickness of the first filter layer 51 is preferably 1 mm or more. The thickness of the second filter layer 52 is 0.35 to 0.45 mm. In the third filter layer 53, the diameter of the wire constituting the wire net (hereinafter referred to as the wire diameter) is, for example, φ0.15 to 0.35 mm. In the case where the third filter layer 53 is a plain weave wire mesh, the thickness is approximately twice the wire diameter, for example, 0.3 to 0.7 mm.

  In addition, when the same third filter layer 53 is provided so as to cover both the first filter layer 51 and the second filter layer 52, any surface of the filter 44 is disposed on the first filter layer 51. It becomes very difficult to understand whether it is the surface that is being done. Therefore, when assembling the spin pack 4, there is a possibility that the filter 44 is mistakenly attached upside down (so that the second filter layer 52 is located upstream of the first filter layer 51). If the vertical positions of the first filter layer 51 and the second filter layer 52 are reversed, desired filtration performance cannot be obtained. Specifically, the molten polymer containing the gel-like portion first passes through the second filter layer 52 having a small filtration particle size, and the second filter layer 52 is immediately clogged. In the present embodiment, the third filter layer 53 is provided only on the second filter layer 52, and the first filter layer 51 is exposed. Therefore, it becomes easy to know which surface of the filter 44 is the surface on the first filter layer 51 side, and the filter 44 is not attached upside down.

  The three filter layers 51 to 53 may be individually assembled to the spinning pack 4, or may be integrated in a state where the three filter layers 51 to 53 are laminated in advance. For example, three filter layers 51 to 53 may be joined by spot welding. Alternatively, the three filter layers 51 to 53 may be fixed to each other by ring-shaped fixing members (rims) attached to the outer peripheral portions of the three filter layers 51 to 53. In this case, since the gap between the outer peripheral portions of the three filter layers 51 to 53 is closed by the ring-shaped fixing member, the molten polymer is prevented from leaking from the gap. As described above, when the three filter layers 51 to 53 are integrated, it is easy to attach the filter 44 when the spin pack 4 is assembled or to remove the filter 44 when the spin pack 4 is disassembled. become.

  The spinning of the molten polymer in the spinning pack 4 described above will be described. When the spinning pack 4 is inserted into the storage recess 30 of the heating box 3 and attached to the pack attachment portion 31, the molten polymer flowing in the polymer flow path 34 of the pack attachment portion 31 is introduced into the spinning pack 4 from the introduction portion 47. To be introduced.

  The molten polymer introduced from the introduction portion 47 immediately flows into the buffer space 49 through the polymer supply hole 43a. In the buffer space 49, the pressure of the molten polymer is made uniform, and the molten polymer spreads in the surface direction of the filter 44. Then, the filter 44 passes through the filter 44 almost uniformly throughout the entire area.

  In the filter 44, the molten polymer first passes through the first filter layer 51. At that time, the gel-like portion in the molten polymer is divided at the acute angle portion of the short metal fiber 50 having a polygonal cross section of the first filter layer 51 and is subdivided. At the same time, relatively large foreign substances contained in the molten polymer are collected by the first filter layer 51. The molten polymer that has passed through the first filter layer 51 passes through the second filter layer 52 and the third filter layer 53. Since the second filter layer 52 has a filtration particle size smaller than that of the first filter layer 51, small foreign matters that are not collected by the first filter layer 51 are removed by the second filter layer 52.

  The molten polymer that has passed through the filter 44 flows into the plurality of nozzles 54 of the spinneret 45 located immediately below the filter 44, and is spun from the plurality of nozzles 54 to form a plurality of filaments f.

  The appropriate filtration particle size of the filter 44 varies depending on the thickness of the yarn to be produced. Specifically, the polymer spinning amount from the spinneret 45 and the filtration particle size of the filter 44 are preferably in the following relationship.

  If a thick yarn is produced using the filter 44 with a small filtration particle size (that is, the amount of spinning of the molten polymer is increased), the pressure in the spin pack 4 becomes too high, and the filter 44 is clogged early. Therefore, the service life of the spinning pack 4 is shortened. Therefore, in such a case, it is necessary to make the polymer spinning amount below a certain amount. Specifically, when the filtration particle size of the first filter layer 51 is 20 to 50 μm and the filtration particle size of the second filter layer 52 is 10 to 30 μm, the spinning amount is set to 80 g / min or less. Furthermore, when the filter particle size of the filter 44 is considerably small, that is, when the filter particle size of the first filter layer 51 is 20 to 30 μm and the filter particle size of the second filter layer 52 is 10 to 20 μm, the spinning amount is 40 g. / Min or less.

  Contrary to the above, if the filter 44 having a large filtration particle size is used to produce a thin yarn (decrease the amount of molten polymer spun), the pressure in the spin pack 4 becomes too low and the polymer Spinning becomes unstable. Therefore, in such a case, it is necessary to set the polymer spinning amount to a certain amount or more. Specifically, when the filtration particle size of the first filter layer 51 is 50 to 80 μm and the filtration particle size of the second filter layer 52 is 20 to 40 μm, the spinning amount is set to 50 g / min or more.

According to the spinning pack 4 described above, the following effects can be obtained.
(1) The filter 44 has the 1st filter layer 51 formed by sintering the metal short fiber 50a of a polygonal cross section. When passing through the first filter layer 51, the gel-like portion present in the molten polymer is divided so as to be chopped by the acute angle portion of the short metal fiber 50a having a polygonal cross section. Accordingly, the gel-like portion is sufficiently subdivided by the first filter layer 51 even without the particulate filter medium.

(2) The spinning pack 4 has a very simple configuration in which the introduction portion 47, the buffer space 49, the filter 44, and the spinneret 45 are arranged in series in this order. Therefore, abnormal retention of the polymer does not occur and thermal degradation of the polymer is suppressed.

  Further, the introduction part 47 and the buffer space 49 are directly connected by the polymer supply hole 43a, and there is no granular filter medium or a polymer distribution member between the introduction part 47 and the filter 44. Therefore, the time until the molten polymer introduced from the introduction part 47 reaches the filter 44 is very short. Therefore, the time from when the molten polymer is introduced into the spin pack 4 until it is spun from the plurality of nozzles 54 of the spinneret 45 is shortened, and alteration due to thermal degradation of the polymer in the spin pack 4 can be suppressed as much as possible. .

(3) Since the buffer space 49 exists between the introducing portion 47 and the filter 44, the molten polymer is filtered after the pressure of the molten polymer introduced from the introducing portion 47 is made uniform in the buffer space 49. Pass through. In addition, the first filter layer 51 of the filter 44 has high rigidity formed by sintering the short metal fibers 50a. Unlike the conventional granular filter medium, the first filter layer 51 can be easily observed even when the pressure of the molten polymer acts. Does not open or collapse. Therefore, it is unlikely that the porosity changes locally at a part of the filter 44. As described above, when the molten polymer passes through the filter 44, the flow is less likely to be biased, and the difference in the amount of molten polymer spun between the plurality of nozzles 54 can be suppressed small.

  The spin pack 4 of this embodiment handles a relatively low viscosity polymer having a melt polymer viscosity of 300 Pa · s or less. Therefore, even if there is no member for polymer distribution from the introduction part 47 to the filter 44, the buffer space 49 above the spinneret 45, the metal short fiber having a certain thickness and having a polygonal cross section With the filter 44 including the first filter layer 51 formed by sintering 50a, the molten polymer can be dispersed, and the thermal history can be made uniform.

  Further, the buffer space 49 is formed so as to extend in the surface direction of the filter 44 so as to straddle all the nozzles 54 of the spinneret 45. As a result, the molten polymer introduced from the introduction portion 47 spreads in the surface direction of the filter 44 and reaches a position directly above all the nozzles 54 and then passes through the filter 44. Therefore, variation in the amount of polymer flowing to each of the plurality of nozzles 54 is reduced, and the amount of polymer spun between the plurality of nozzles 54 is made more uniform.

(4) As described above, since the rigidity of the first filter layer 51 is high, the first filter layer 51 is not easily opened or crushed by the pressure of the molten polymer. Therefore, the change in the porosity of the first filter layer 51 after the start of use is much more gradual than that of a conventional granular filter medium that is easily opened or compressed by the polymer pressure. Accordingly, a decrease in the filtration particle size and an increase in the amount of increase in the polymer pressure in the spin pack 4 are suppressed, and the pack life of the spin pack 4 is extended.

(5) In the filter 44, the 3rd filter layer 53 is laminated | stacked on the 2nd filter layer 52 in which the metal short fiber 50b tends to drop out. As a result, the second filter layer 52 is sandwiched between the first filter layer 51 and the third filter layer 53, and the second metal short fibers 50b are prevented from falling off from the second filter layer 52. On the other hand, the third filter layer 53 is not laminated on the first filter layer 51, and the surface of the first filter layer 51 opposite to the second filter layer 52 is exposed. Since the first metal short fibers 50a do not easily fall off from the first filter layer 51, there is no problem even if the third filter layer 53 is not provided.

  Since the third filter layer 53 is provided only on the second filter layer 52, it is possible to prevent the short metal fibers from falling off while suppressing the thickness of the entire filter 44 to be small. Further, since the first filter layer 51 is not covered with the third filter layer 53, it can be easily recognized which surface of the filter 44 is the surface on the first filter layer 51 side. Therefore, when the filter 44 is assembled to the spin pack 4, the filter 44 is prevented from being attached in the reverse direction by mistake.

(Example)
Next, specific examples of the present invention will be described.

(A) Effect verification of first filter layer (polygonal cross-section metal short fiber filter layer) Spinning pack (example) in which the filter includes a first filter layer made of short metal fibers having a polygonal cross section, and the first filter layer And a spinning pack (comparative example) containing no yarn, a yarn composed of a plurality of filaments was spun, and the yarn was wound around a package. In any of the spinning packs of the example and the spinning pack of the comparative example, the particulate filter medium is not used. Test conditions other than the above are shown below.

[Test conditions]
(1) Spinning conditions (common to Examples and Comparative Examples)
Polymer type: PET semidal polymer Viscosity: 200 Pa · s
Yarn brand: FDY 55dtex / 48f
Discharge rate: 25 g / min

(2) Filter (a) Example (upper layer) Polygonal section metal short fiber filter layer Filtration accuracy: 38 μm, material: SUS430, thickness: 2.0 mm, porosity 70%
(Middle layer) Circular section metal short fiber filter layer Filtration accuracy: 20 μm, Material: SUS316, Thickness: 0.35 mm, Porosity: 70%
(Lower layer) Plain woven wire mesh filter layer Number of meshes: 50 mesh, Material: SUS304, Wire diameter: φ0.18 mm, Opening ratio 42%
(B) Comparative example (upper layer) Plain woven wire mesh filter layer Number of meshes: 400 mesh × 4 layers, Material: SUS304, Wire diameter: φ0.1 mm, Opening ratio: 36%
(Middle layer) Circular cross-section metal short fiber filter layer (same as middle layer in the above embodiment, details omitted)
(Lower layer) Plain woven wire mesh filter layer (same as the lower layer in the above example, details omitted)

(3) Winding conditions (common to Examples and Comparative Examples)
Yarn feeding speed before drawing: 2030 m / min (yarn feeding speed by godet rollers 12 to 14 in FIG. 1)
Yarn feeding speed after drawing: 4575 m / min (yarn feeding speed by godet rollers 15 and 16 in FIG. 1)
Winding speed: 4520 m / min (yarn winding speed in the winding device 18 in FIG. 1)

  The fluff rate was compared between the package wound with the yarn spun from the spinning pack of the example and the package wound with the yarn spun from the spinning pack of the comparative example. The “fluff rate” is the ratio of the number of packages with fluff to the total target packages. In the package produced using the spinning pack of the example, the fluff rate was 0.14%. On the other hand, the fluff rate of the package produced using the spin pack of the comparative example was 8.85%.

  When the molten polymer is spun from the nozzle without sufficiently subdividing the gel-like portion in the molten polymer, the filament spun from the nozzle is easily cut, and as a result, fluff is generated in the package. In this regard, in the package of the example, the fluff rate is significantly lower than that of the comparative example. This is presumably because the spin pack of the example has the first filter layer 51 made of short metal fibers having a polygonal cross section, so that the gel-like portion is sufficiently subdivided.

(B) Verification about the relationship between the filter particle size of the filter and the polymer spinning amount The filter particle sizes of the first filter layer (polygonal cross-section metal short fiber filter layer) and the second filter layer (circular cross-section metal short fiber filter layer) are respectively Three different types of filters X, Y, and Z were prepared. The specifications of the filters X, Y, and Z and the polymer conditions are shown below.

[Filter X]
(First filter layer) Filtration particle size: 25 μm, thickness: 1.0 mm, 3.0 mm
(Second filter layer) Filtration particle size: 10 μm
(Third filter layer) Number of meshes: 50 mesh [Filter Y]
(First filter layer) Filtration particle size: 38 μm, thickness: 1.0 mm, 3.0 mm
(Second filter layer) Filtration particle size: 15 μm
(Third filter layer) Number of meshes: 50 mesh [Filter Z]
(First filter layer) Filtration particle size: 62 μm, thickness: 1.0 mm, 3.0 mm
(Second filter layer) Filtration particle size: 30 μm
(Third filter layer) Number of meshes: 50 mesh [polymer]
Polymer type: PET semidal polymer Viscosity: 200 Pa · s

  Under the above conditions, the “thickness of 1.0 mm, 3.0 mm” of the first filter layer means that the filters X, Y, and Z have two types of first filters of thickness 1.0 mm and 3.0 mm, respectively. Indicates that a layer was used.

  With respect to the three types of filters X, Y, and Z, the polymer pressure (hereinafter also referred to as pack pressure) at the spinning pack inlet when the polymer spinning amount from the spinneret was changed was measured. More specifically, the upper limit of the applicable range of the polymer spinning amount is verified for the filters X and Y having a small filtration particle size, and the lower limit of the applicable range of the polymer spinning amount for the filter Z having a large filtration particle size. Verified. The polymer spinning amount was controlled by changing the discharge rate of the gear pump that supplies the molten polymer to the spinning pack. The measurement results are shown in Table 1.

If the pack pressure is too large, the filter is clogged early and the life of the spin pack is shortened. If the pack pressure is too low, the polymer discharge becomes unstable. Here, the appropriate range of the pack pressure is set to 70 to 150 kg / cm ² . In Table 1, “◯” indicates that the pack pressure is within the appropriate range, and “X” indicates that the pack pressure is outside the appropriate range.

  In the filters X and Y having a small filtration particle size, the pack pressure becomes too high when the polymer spinning amount is large. Specifically, in the filter Y, the polymer spinning amount is 90 g / min or more, and the pack pressure exceeds the upper limit of the appropriate range. Further, in the filter X having a filtration particle size smaller than that of the filter Y, the polymer spinning amount is 50 g / min or more, and the pack pressure exceeds the upper limit of the appropriate range. On the other hand, in the filter Z having a large filtration particle size, the pack pressure becomes too low when the polymer spinning amount is small. Specifically, when the polymer spinning rate is 40 g / min or less, the pack pressure is lower than the lower limit of the appropriate range.

  Next, modified embodiments in which various modifications are made to the embodiment will be described. However, components having the same configuration as in the above embodiment are given the same reference numerals and description thereof is omitted as appropriate.

1] In the above embodiment, the filter 44 is positioned at the lower end of the buffer space 49, and the spinneret 45 is in contact with the lower surface of the filter 44 (see FIG. 2). On the other hand, as shown in FIG. 5, the filter 44 may be disposed in the middle of the lower space of the buffer space 49, and the spinneret 45 may be disposed so as to contact the buffer space 49 instead of the filter 44. . That is, the spinneret 45 is disposed so as to block the space below the filter 44 in the buffer space 49 from below. In this configuration, the molten polymer that has passed through the filter 44 is once stored in a space below the filter 44 and then flows into the plurality of nozzles 54 of the spinneret 45. Alternatively, a spacer is disposed between the three filter layers 51 to 53 and the spinneret 45, and the three filter layers 51 to 53 are separated from the spinneret 45 by the thickness of the spacer. Also good. In other words, it can be said that the buffer space 49 is vertically separated by the filter 44, and the lower space of the buffer space 49 is formed by the spacer between the filter 44 and the spinneret 45.

2] The spin pack 4 of the above embodiment spins one yarn Y composed of a plurality of filaments f, but the present invention is also applied to a spin pack that spins two or more yarns Y. Can be applied.

  For example, the spinning pack may have a configuration including one introduction portion 47 and a plurality of nozzle groups that respectively spin two or more plurality of yarns. The spin pack 4A of FIG. 6 includes a polymer inflow member 43, a filter 44, and a spinneret 45A. The polymer inflow member 43 and the filter 44 have the same configuration as the spinning pack 4 of the above embodiment. That is, the polymer inflow member 43 has one introduction portion 47 and one buffer space 49 communicating with the one introduction portion 47 through the polymer supply hole 43a. The filter 44 includes a first filter layer 51 that is a polygonal cross-section metal short fiber filter layer, a second filter layer 52 that is a circular cross-section metal short fiber filter layer, and a third filter layer 53 formed of a wire mesh.

  The spinneret 45A includes a first nozzle group 60a composed of a plurality of nozzles 54a and a second nozzle group 60b composed of a plurality of nozzles 54b. The plurality of nozzles 54a of the first nozzle group 60a and the plurality of nozzles 54b of the second nozzle group 60b are arranged separately in the left-right direction in the drawing. An opening 41a is formed at the lower end of the case member 41A. In the opening 41a, the plurality of nozzles 54a of the first nozzle group 60a and the plurality of nozzles 54b of the second nozzle group 60b are exposed. The molten polymer in one buffer space 49 passes through the filter 44 and is supplied to the first nozzle group 60a and the second nozzle group 60b, respectively. Then, the melted polymer is spun from the plurality of nozzles 54a of the first nozzle group 60a to form the first yarn Y1 composed of the plurality of filaments f1. In addition, the melted polymer is spun from the plurality of nozzles 54b of the second nozzle group 60b, whereby the second yarn Y2 composed of the plurality of filaments f2 is formed.

  When the dispersion of the polymer spinning amount among the plurality of nozzles 54 is large, a difference occurs in the polymer spinning amount between the two nozzle groups 60a and 60b, and 2 spun from each nozzle group 60a and 60b. The thicknesses of the yarns Y1 and Y2 are greatly different. However, by adopting the configuration of the filter or the like of the present invention, the amount of polymer spinning among the plurality of nozzles 54 is made uniform, and the nozzle 54a belonging to the first nozzle group 60a and the nozzle belonging to the second nozzle group 60b. The difference in the amount of polymer spinning with respect to 54b is also reduced. Therefore, the thickness between the first yarn Y1 and the second yarn Y2 can be made substantially equal.

  The spinneret may have three or more nozzle groups, and three or more yarns may be spun from the three or more nozzle groups, respectively. In FIG. 6, only one buffer space 49 is formed in the polymer inflow member 43, but the polymer inflow member 43 corresponds to each of a plurality of nozzle groups of two or more, and corresponds to one introduction portion 47. A plurality of buffer spaces 49 that communicate with each other may be formed. Furthermore, a plurality of introducing portions 47 may be provided corresponding to the plurality of nozzle groups, respectively.

3] The spinning pack 4 can be modified as follows in addition to the above. For example, a member for distributing the molten polymer may be provided between the molten polymer introduction portion 47 and the filter 44. Further, a polymer distribution member may be provided between the filter 44 and the spinneret 45.

4] The spinning take-up machine 2 of the above embodiment has a configuration in which the yarn spun from the spinning pack is stretched by the five godet rollers that are heating rollers. The configuration is not limited and can be changed as appropriate. Further, it is not essential that the godet roller is a heating roller, and some of the godet rollers may be non-heating rollers. Furthermore, all the godet rollers may be non-heated rollers, and the spinning take-up machine 2 may send the yarn Y spun from the spinning pack 4 to the winding device 18 without stretching.

44 Filter 45 Spinneret 50a First metal short fiber 50b Second metal short fiber 51 First filter layer 52 Second filter layer 53 Third filter layer

Claims (8)

A filter for filtering a molten polymer spun from a spinneret before spinning,
A first filter layer formed by sintering first short metal fibers having a polygonal cross section;
A second filter layer laminated on the first filter layer and sintered with a second short metal fiber having a circular cross section; and
A third filter layer laminated on the second filter layer,
The filter, wherein the third filter layer is not laminated on the first filter layer, and a surface of the first filter layer opposite to the second filter layer is exposed.   The filter according to claim 1, wherein a filtration particle size of the second filter layer is smaller than a filtration particle size of the first filter layer.   The fiber diameter of the said 2nd metal short fiber of a 2nd filter layer is smaller than the conversion diameter in the circular cross section of the said 1st metal short fiber of the said 1st filter layer, It is characterized by the above-mentioned. filter. The third filter layer is formed of a wire mesh;
The number of meshes of the said 3rd filter layer is 30-100 mesh, The filter in any one of Claims 1-3 characterized by the above-mentioned.   The filter according to any one of claims 1 to 4, wherein the first filter layer, the second filter layer, and the third filter layer are integrated. A spinning method for spinning the molten polymer filtered by the filter according to any one of claims 1 to 5 from the spinneret,
The filtration particle size of the first filter layer is 20 to 50 μm, the filtration particle size of the second filter layer is 10 to 30 μm,
A spinning method, wherein the spinning amount of the molten polymer from the spinneret is 80 g / min or less. The filtration particle size of the first filter layer is 20-30 μm, the filtration particle size of the second filter layer is 10-20 μm,
The spinning method according to claim 6, wherein the spinning amount of the molten polymer from the spinneret is 40 g / min or less. A spinning method for spinning the molten polymer filtered by the filter according to any one of claims 1 to 5 from the spinneret,
The filtration particle size of the first filter layer is 50 to 80 μm, the filtration particle size of the second filter layer is 20 to 40 μm,
A spinning method, wherein the spinning amount of the molten polymer from the spinneret is 50 g / min or more.