JP2014188991A - Multilayer extrusion molding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device that controls thickness of each layer by a simple method to uniform the film thickness in the width direction of each layer, in manufacturing a multilayer film from a die by coextruding a molten resin in a feed block method.SOLUTION: A feed block of a multilayer extrusion molding device comprises a flow plate, a beak, and a die joint. The flow plate has a plurality of openings for introducing a plurality of molten resins. The beak has an inner layer passage and an outer layer passage that are passages for the plurality of molten resins introduced to the plurality of openings and a confluent passage. The inner layer passage has a rectangular cross section and the outer layer passage has a rectangular cross section and merges to the inner layer passage from the side. The confluent passage where the outer layer passage merges to the inner layer passage has a rectangular cross section. The die joint has the confluent passage and a passage that connects to a single layer die. A partition wall having a plurality of heating elements in the width direction is arranged between the inner layer passage and the outer layer passage, the temperature of the plurality of heating elements being controlled.

Description

  The present invention relates to a multilayer film extrusion molding apparatus, and more particularly to a multilayer extrusion molding apparatus using a feed block type coextrusion method in which a plurality of molten resins are joined together by a feed block and discharged from a single layer die.

  Thermoplastic resin films are used in various fields, and at that time, a plurality of properties suitable for the application are imparted. As a means for imparting these characteristics, a method of forming a multilayer film is used.

  Co-extrusion methods for producing a thermoplastic resin as a multilayer film include a multi-manifold method and a feed block method. In the multi-manifold system, a plurality of molten resins are spread in the width direction (the width direction refers to the width direction of the manufactured multilayer film, the same applies hereinafter) at each independent manifold in the die, and merged immediately before the die exit. To produce a film. Multi-manifold dies are complex in structure and expensive to manufacture, and dies must be prepared for each layer structure, film thickness and width.

  FIG. 1 shows a conventional coextrusion method using a feed block system. In the co-extrusion method using the feed block system shown in FIG. 1, three types of thermoplastic resins A, B, and C are supplied from the respective introduction paths 11a to 11c of the flow plate 10, and the junction P is reached via the connection paths 12a to 12c. In the extrusion width direction (perpendicular to the plane of the paper) by the same die 31 that generates the single-layer film through the merged beak 20 and the merged molten resin through the merge channel 32 of the die connection portion 30. A multilayer film (not shown) is formed by extruding from the widened slit-shaped outlet 34.

  As described above, in the feed block method, a plurality of molten resins are merged in the feed block, and then developed in the width direction by a single manifold in the die to generate a film. The die used in a single layer can be used, and the layer configuration can be easily changed by changing the combination of feed blocks. On the other hand, in general, when a plurality of resins are merged in the feed block, the larger the ratio of the viscosity of each resin, the ratio of the flow velocity, or the ratio of the cross-sectional area, the more the disorder of the interface of the resin after the merge occurs. It is known to be easy. In addition, after joining at the feed block, the manifold must be expanded to a width of about 10 times, and the distance to the discharge port of the die is long, so it is difficult to make the thickness of each layer uniform in the width direction. It is known that the longer the flow path after merging, the more enveloping phenomenon that each layer becomes uneven due to the difference in flow rate and melt viscosity.

  In Patent Document 1, by adjusting the flow path width of the resin with the notch of the layer thickness adjuster provided in the feed block, the flow rate is distributed to make the thickness distribution in the width direction of each layer of the multilayer film uniform. An extrusion apparatus is shown. In this method, it is necessary to change the shape of the layer thickness adjuster in accordance with the resin and the discharge conditions, and in addition, it is necessary to change the shape of the layer thickness adjuster for each layer when forming four or more layers. It is difficult to.

Patent Document 2 discloses an extrusion apparatus and a method for producing a multilayer film that optimizes the cross-sectional shape of the flow path at the confluence portion of the feed block to make the thickness distribution in the width direction of each layer of the multilayer film uniform. . However, since only the flow path shape of the resin of the outer layer can be controlled and applied, when the viscosity or flow rate of the intermediate layer is large, the flow rate distribution of the intermediate layer becomes convex and uneven thickness envelopment occurs.
Patent Document 3 discloses an apparatus that controls the temperature in the feed block to equalize the viscosity of each resin and reduce uneven thickness. Although the flow characteristics are controlled by adjusting the temperature, there is a limit to the adjustment of the flow characteristics by adjusting the temperature, and when the viscosity difference or flow rate ratio is large, only the temperature adjustment makes the flow profile of each layer uniform. It is difficult.

Japanese Patent Laid-Open No. 7-241897 JP 2002-225107 A Japanese Patent Laid-Open No. 11-309770

  Therefore, in view of the above problems, the present invention controls the thickness of each layer by a simple method when a multilayer film is manufactured from a die by co-extrusion of a molten resin by a feed block method. It is an object of the present invention to provide an apparatus for uniforming the thickness. In the present invention, the die mainly refers to a flat T die such as a coat hanger die, a fish tail die, or a straight manifold die.

Therefore, the invention of claim 1 of the present invention is
A multilayer extrusion molding apparatus for joining a plurality of molten resins in a feed block and extruding from a single layer die to produce a multilayer film,
The feed block is composed of a flow plate, a beak, and a die connection part,
The flow plate has a plurality of openings for charging a plurality of molten resins,
The beak has an inner layer channel, which is a plurality of molten resin channels introduced into the plurality of openings, an outer layer channel, and a combined channel,
The inner layer channel is a channel having a rectangular cross section,
The outer layer channel is a channel having a rectangular cross section that merges from the side with respect to the inner layer channel,
The joint channel is a channel having a rectangular cross section in which the inner layer channel and the outer layer channel are merged,
The die connection part has a flow path connected to the combined flow path and the single-layer die,
Between the inner layer flow path and the outer layer flow path, a partition wall having a plurality of heating elements in the width direction (the width direction refers to the width direction of the film to be formed; the same applies hereinafter) is provided.
A multilayer extrusion molding apparatus that controls the temperature of the plurality of heating elements.

  The invention according to claim 2 is the multilayer extrusion molding apparatus according to claim 1, wherein a beak having a plurality of heating elements in the width direction is provided at a position facing the partition wall of the outer layer flow path. is there.

  The invention according to claim 3 is characterized in that a heat generating element of a beak is operated with respect to a resin having a high viscosity or a low MFR among resins constituting the inner layer or the outer layer, and in particular, heating is performed by a heat generating element at an end in the width direction. The multilayer extrusion molding apparatus according to claim 1 or 2.

  The invention according to claim 4 is characterized in that, among the resins constituting the inner layer or the outer layer, a low viscosity or high MFR resin is heated by a heating element at the center in the width direction among the heating elements of the beak. Item 3. The multilayer extrusion molding apparatus according to Item 1 or 2.

  A fifth aspect of the present invention is the multilayer extrusion molding apparatus according to any one of the first to fourth aspects, wherein a plurality of the beaks are provided.

The feed block according to the present invention can individually control the temperature of the resin in the inner layer channel and the outer layer channel by disposing a heating element on the opposite side of the partition wall and the outer channel. In general, a thermoplastic molten resin has a lower viscosity and a higher fluidity as the temperature rises. Therefore, if the temperature of the layer that becomes thinner in the width direction is raised, the flow rate of the resin increases, so that the layer thickness becomes uniform. Further, in the case of coextrusion of resins having different viscosities or MFRs, the film thickness becomes non-uniform so that a resin having a high viscosity is wrapped with a resin having a low viscosity. That is, since the high-viscosity resin has a thin end in the width direction, enveloping can be suppressed by increasing the flow rate by increasing the temperature of the end of the flow path of the beak. Similarly, since the low-viscosity resin has a thin center in the width direction, enveloping can be suppressed by increasing the flow rate by raising the temperature in the center of the flow path of the beak.
The feed block in the present invention can adjust the thickness distribution of each molten resin by controlling the temperature of a plurality of heating elements, and as a result, molding defects can be reduced.

The figure which shows the coextrusion method by the conventional feed block system. 1 is a schematic diagram of a feed block of a three-layer film extrusion apparatus illustrating one embodiment of the present invention. The schematic which looked at the flow plate of FIG. 2 in the flow direction from the upstream. Sectional drawing of A-A 'of FIG. 2 showing the structure of a beak. The feed block schematic diagram of the extrusion molding apparatus of the 5 layer film which illustrated the 2nd Embodiment of this invention. Schematic which looked at the flow plate of FIG. 5 from the upstream in the flow direction. Sectional drawing of B-B 'of FIG. Sectional drawing of the produced | generated three-layer film. The temperature distribution of the flow path in one embodiment of this invention. The resin distribution of the combined flow path in one embodiment of this invention. The figure which shows the temperature dependence of shear viscosity.

  Embodiments of a multilayer extrusion molding apparatus according to the present invention will be specifically described below with reference to the drawings. As a first embodiment, a feed block of a three-layer film extrusion molding apparatus using three kinds of resins is shown in FIGS. FIG. 2 is a view showing a cross section of a feed block provided in the multilayer extrusion molding apparatus of the present invention, and the feed block includes a flow plate 10, a beak 20, and a die connection part 30. The flow plate 10 has introduction paths 11a to 11c having a round hole-shaped cross section, which are a plurality of openings into which a plurality of molten resins are poured. The beak 20 includes an inner layer channel 25, outer layer channels 26 and 27, and a combined channel 28. The die connection part 30 has a flow path 32 connected to the combined flow path 28 and a single layer die (not shown).

  The flow plate 10 will be described. FIG. 3 is a schematic view of the flow plate 10 as viewed from the upstream side in the flow direction. Fig.3 (a) is the flow plate 10 in the case of connecting the three extruders 1-3 (FIG. 2). The introduction paths 11a to 11c opened in the shape of round holes to which the extruders 1 to 3 are connected are connected to the communication paths 12a to 12c while changing to a rectangular shape, and open to the beak side. The number of extruders is not limited to three, and FIG. 3B shows a flow plate in the case of connecting two extruders. The introduction paths 11a and 11b to which the extruders 1 and 2 are connected open in a round hole shape, and the introduction path 11a is branched into two inside the flow plate 10 and connected to the communication paths 12a and 12c while changing into a rectangle. The introduction path 11b is connected to the communication path 12b while changing to a rectangle, and opens to the beak side.

  The beak 20 will be described. As shown in FIG. 2, the beak 20 is connected to the communication path 12b, the inner layer flow path 25 having a rectangular cross section connected to the communication path 12b, the outer layer flow path 26 having a rectangular cross section connected to the communication path 12a, and the communication path 12c. The outer layer channel 27 having a rectangular cross section, and the merge channel 28 having a rectangular section in which the inner layer channel 25, the outer layer channel 26, and the outer layer channel 27 merge. The inner layer flow path 25 is a flow path having a rectangular cross section, the outer layer flow paths 26 and 27 are flow paths having a rectangular cross section that merge from the side surface with respect to the inner layer flow path 25, and the combined flow path 28 is the inner layer flow path 25. And the outer layer channels 26 and 27 are combined with each other, and the partition walls 21 and 23 between the inner layer channel 25 and the outer layer channels 26 and 27 are arranged in the width direction (the width direction is the shape of the film to be molded). By having a plurality of heating elements 43 and 44 in the width direction (the same applies hereinafter), a temperature distribution is given in the width direction of the resin of the inner layer flow path 25, and the flow rate can be adjusted by causing a difference in viscosity. .

  By providing a plurality of heating elements 41, 42 in the width direction of the outer layer channels 26, 27 facing the partition walls 21, 23, a temperature distribution is given in the resin width direction of the outer layer channels 26, 27, and The flow rate can be adjusted by the difference in viscosity.

FIG. 4 is a cross-sectional view taken along line AA ′ of FIG. Five heating elements 41 to 44 arranged in the partition wall 21, the partition wall 23, and the beak housing 29 are arranged in the width direction of each flow path indicated by an arrow 53, and each heating element can individually generate heat. . Here, the number of the heat generating elements 41 to 44 is not limited to five, but may be plural, and may have a heat absorbing function like a Peltier element.
By arranging thermometers 81 and 82 on the outer layer flow paths 26 and 27 side with respect to the respective heating elements 41 to 42, and arranging thermometers 83 and 84 on the inner layer flow path 25 side with respect to the respective heating elements 43 to 44, The calorific value can be fed back.

  As shown in FIG. 2, the die connection portion 30 has a flow path 32 having a rectangular cross section, and connects the combined flow path 28 of the beak 20 and the flow path of the die 31.

  As a second embodiment, a feed block of a five-layer film extrusion molding apparatus using two beaks is shown in FIGS. The feed block 4 shown in FIG. 5 includes a flow plate 10, a first beak 80, communication blocks 60 and 62, a second beak 70, and a die connection part 30.

  The flow plate 10 includes, for example, round hole-shaped cross-section introduction paths 11a to 11e connected to five unillustrated extruders, and rectangular cross-section connecting paths 12a to 12e connected thereto, and the first beak 80 is formed. The communication block 60 and the communication block 62 are connected. FIG. 6 shows a schematic view of the flow plate 10 viewed from the upstream side in the flow direction when, for example, three extruders 1 to 3 are connected. The introduction paths 11a to 11c to which the extruders 1 to 3 are connected are opened in a round hole shape, and the introduction paths 11a and 11c are branched into two inside the flow plate 10 and change into a rectangular shape, respectively, and the communication paths 12a and 12c, Connected to 12d and 12e, the introduction path 11b is connected to the communication path 12b while changing to a rectangle, and opens to the beak side. The number of extruders is not limited to three, and in the case of a five-layer film using less than five extruders, the introduction path 11 is appropriately branched and connected to the communication paths 12a to 12e having a rectangular cross section. Use a flow plate.

  The shape of the first beak 80 is the same as that described in the first embodiment, and is omitted.

  The communication paths 12a to 12c of the flow plate 10 are respectively connected to the outer layer flow path 26, the inner layer flow path 25, and the outer layer flow path 27 of the first beak 80, and the communication path 12d and the communication path 12e of the flow plate 10 communicate with each other. The communication path 61 of the block 60 and the communication path 63 of the communication block 62 are connected.

  The second beak 70 has a rectangular cross-section inner layer flow path 75 connected to the combined flow path 28, a rectangular cross-section outer layer flow path 76 connected to the communication path 61, and a rectangular shape connected to the communication path 63. The outer layer channel 77 having a cross-section, and the merged channel 78 having a rectangular cross section in which the inner layer channel 75, the outer layer channel 76, and the outer layer channel 77 are joined. Further, the second beak 70 includes a partition wall 71 of an inner layer channel 75 and an outer layer channel 76 and a partition wall 73 of an inner layer channel 75 and an outer layer channel 77 in a beak housing 79. The partition walls 71, 73 have a plurality of heating elements 47, 48 in the width direction, thereby providing a temperature distribution in the resin width direction of the inner layer flow path 75 and adjusting the flow rate by causing a difference in viscosity. .

  By providing a plurality of heating elements 45 and 46 in the width direction of the positions facing the partition walls 71 and 73 with respect to the outer layer channels 76 and 77, a temperature distribution is given in the width direction of the resin of the outer layer channels 76 and 77, The flow rate can be adjusted by the difference in viscosity.

  FIG. 7 is a cross-sectional view taken along B-B ′ of FIG. Five heating elements 45 to 48 arranged in the partition wall 71, the partition wall 73, and the beak housing 79 are arranged in the width direction of each flow path indicated by an arrow 53, and each heating element can individually generate heat. . Here, the number of the heat generating elements 45 to 48 is not limited to five, but may be plural, and may have a heat absorbing function like a Peltier element.

  By arranging thermometers 85, 86 on the outer layer flow paths 76, 77 side for each heating element 45-46, and arranging thermometers 87, 88 on the inner layer flow path 75 side for each heating element 47-48. The calorific value can be fed back.

  The die connection part 30 has a channel 32 having a rectangular cross section, and connects the combined channel 78 of the second beak 70 and the channel of the die 31.

  In the second embodiment, the number of beaks is not limited to two, and a multilayer film of five or more layers can be formed by using three or more beaks in an overlapping manner.

<Example 1>
As an example of the first embodiment, consider the production of a three-layer film in which the inner layer is EVOH and the outer layer is LDPE. The shear viscosity with respect to the temperature of each resin is shown in FIG. When extruded at 250 ° C., the joint channel 32 immediately after joining at the beak 20 has a uniform thickness as shown in FIG. 10 (a), which is a cross-section at CC ′ in FIG. 2, but the viscosity of EVOH is high. Therefore, enveloping occurs downstream, and the film discharged from the T-die has a thin end portion of the EVOH layer and the center of the LDPE layer as shown in FIG. According to the present invention, the temperature distribution of the inner layer flow path as shown in FIG. 9A is obtained by increasing the widthwise ends of the heating elements 43 and 44 and the center of the heating elements 41 and 42 in the width direction. Since the temperature distribution of the outer layer flow path is as shown in FIG. 9B, the flow rate of the thin portion of each layer of the generated sheet is increased, the film thickness is uniformed, and the distribution is as shown in FIG.

<Example 2>
In general, since the pressure-bonding property between EVOH and LDPE is poor, the production of a five-layer film in which an adhesive layer is added between the inner layer EVOH and the outer layer LDPE is considered as the second embodiment. Even in that case, since the inner layer EVOH and the adhesive layer are integrally uneven, the temperature distribution of the inner layer flow path as shown in FIG. 9A and the outer layer flow path as shown in FIG. If a temperature distribution is given, a nearly uniform film thickness similar to the first embodiment can be obtained.

  As described above, according to the multilayer extrusion molding apparatus provided with the feed block of the present invention, the thickness distribution of each layer can be controlled because the viscosity and flow rate in the width direction of the film flow path of each layer can be adjusted. As a result, the film thickness in the width direction of the film can be made uniform.

1-3 ... Extruder 4 ... Feed block 10 ... Flow plate 20 ... Beak 30 ... Die connection part 11 ... Introduction path 12 ... Communication path 21, 23 ... Partition 25 ... Inner layer channel 26, 27 ... Outer layer channel 28 ... Combined channel 29 ... Beak housing 31 ... Die 32 ... Combined channel 34 ... Slit-shaped outlet 41- 48 ... heating element 51 ... flow direction 52 ... thickness direction 53 ... width direction 60, 62 ... communication block 61, 63 ... communication path 70 ... beak 71, 73 ... -Partition 75 ... Inner layer channel 76, 77 ... Outer layer channel 78 ... Combined channel 79 ... Beak housing 80 ... Beak 81-88 ... Thermometer

Claims (5)

A multilayer extrusion molding apparatus for joining a plurality of molten resins in a feed block and extruding from a single layer die to produce a multilayer film,
The feed block is composed of a flow plate, a beak, and a die connection part,
The flow plate has a plurality of openings for charging a plurality of molten resins,
The beak has an inner layer channel, which is a plurality of molten resin channels introduced into the plurality of openings, an outer layer channel, and a combined channel,
The inner layer channel is a channel having a rectangular cross section,
The outer layer channel is a channel having a rectangular cross section that merges from the side with respect to the inner layer channel,
The joint channel is a channel having a rectangular cross section in which the inner layer channel and the outer layer channel are merged,
The die connection part has a flow path connected to the combined flow path and the single-layer die,
Between the inner layer flow path and the outer layer flow path, a partition wall having a plurality of heating elements in the width direction (the width direction refers to the width direction of the film to be formed; the same applies hereinafter) is provided.
A multilayer extrusion molding apparatus that controls the temperature of the plurality of heating elements.   The multilayer extrusion molding apparatus according to claim 1, wherein a beak having a plurality of heating elements in the width direction is provided at a position facing the partition wall of the outer layer flow path.   The beak heating element is operated on a resin having a high viscosity or low MFR among the resins constituting the inner layer or the outer layer, and the heating element is heated by the heating element at the end in the width direction. The multilayer extrusion molding apparatus described in 1.   The resin according to claim 1 or 2, wherein a resin having a low viscosity or a high MFR is heated by a heating element at a center in a width direction of a heating element of a beak among resins constituting the inner layer or the outer layer. Multi-layer extrusion molding equipment.   The multilayer extrusion molding apparatus according to any one of claims 1 to 4, wherein a plurality of the beaks are provided.

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