JP5061237B2 - Extrusion mold with improved crossflow manifold - Google Patents

Description

  The present invention generally relates to an extrusion apparatus for producing a film or sheet of a thermoplastic resin.

  Extrusion molds are used in manufacturing processes that make a variety of products. For example, certain extrusion molds are used to form plastic materials into thin films, sheets, or extended shapes. Two or more different materials that make up separate molten layers (e.g., thermoplastic materials) are integrated in an extrusion mold under pressure to make up as a single laminate material A technique of melt lamination molding method including a process has been developed. Such a process uses laminar flow theory that allows two or more molten layers to be integrated under suitable operating conditions in a common flow path without being mixed at the contact interface. Such multilayer extrusion systems have come to be used as a convenient method for molding multilayer materials of the same or different materials.

  Various extrusion dies have been manufactured for extruding multilayer films. A common form of such an apparatus is one that uses a first mold part that integrates layers of various materials. The integrated material is then planarized and extruded through the second mold part. An example of such a type of device is disclosed in US Pat. No. 5,316,703, which is hereby incorporated by reference in its entirety. When manufacturing a multilayer sheet or a multilayer film, there is a demand for having a uniform thickness in the width direction or the lateral direction (TD) of the extruded sheet. There was a limit to the effectiveness of the device.

  Mold assembly can be modularized and is typically assembled from a plurality of parts, forming a mold station as an integrated device. For example, the mold assembly can be composed of a first mold part and a second mold part. The first mold part and the second mold part constitute a component that allows fluid to be taken into the mold assembly and further pushed out of the mold assembly. The first mold part is provided with a first mold lip part, and the second mold part is provided with a second mold lip part. A feed gap (gap for extruding the molten polymer) that determines the thickness of the fluid film extruded from the mold assembly is formed between the first and second mold lip portions.

  The central feed type extrusion die is generally used in today's resin industry association. The flow of molten polymer entering the manifold branches and, as a result of the branching, is divided into tributaries that flow in opposite directions towards the ends of the manifold. Each tributary flows from the center of the manifold to each end of the manifold, resulting in a pressure drop.

  Typically, a central feed extrusion mold is a teardrop-like flat manifold (which may be in the form of a coat hanger manifold), a tail fin manifold, or T A mold manifold is provided. In order to overcome the pressure drop and ensure that the flow volume is substantially uniform over the entire width of the flow, this type of mold is provided with a transition region flow path to compensate for fluid pressure. Further, it is known that the extrusion die of the center feed type includes a flow path in a transient region for compensating for a two-stage fluid pressure. Such devices are exemplified in U.S. Patent No. 4,372,739 (Vetter et al.) And U.S. Patent No. 5,256,052 (Cloeren).

  The mold assembly can be a fixed extrusion gap or a flexible extrusion gap. In the case of a fixed extrusion gap, the mold lip portions do not move relative to each other, and the thickness dimension of the extrusion gap is always the same. In the case of a flexible extrusion gap, in order to be able to adjust the thickness dimension of the flexible extrusion gap over the width direction of the mold assembly, the mold lip on one side is connected to the mold lip on the other side. It can be moved relative to the part. Generally, the flexible extrusion gap is such that the first mold part is flexible between the rear part and the front part of the first mold part (the first mold lip part comes into contact with this part). This is realized by assembling the first mold part so as to have a web part. The flexible extrusion gap is also realized by means for moving the front part of the first mold part in a local region. By moving the front part, the mold lip part is adjusted relative to the other mold lip part, so that the thickness of the extrusion gap in the desired local area is adjusted. become.

  By utilizing a flexible extrusion gap, a conventional mold assembly design usually allows local adjustment of the extrusion gap to adapt to specific operating conditions. In general, this is accomplished as follows. First, on the downstream side of the mold lip part, the thickness is measured across the width direction of the finished resin sheet or film, adjusted with one or more adjustment bolts, and then the thickness of the finished resin sheet or film The thickness is measured again, and the operation is repeated until the thickness distribution of the film falls within the allowable range.

  With respect to the production of special films such as microporous polyolefin membranes, there are additional requirements in the design of extrusion dies for producing such films. Microporous polyolefin membranes are primary batteries, lithium ion secondary batteries, lithium polymer secondary batteries, nickel / hydrogen secondary batteries, nickel / cadmium secondary batteries, nickel / zinc secondary batteries, silver / zinc secondary batteries. It is useful as a separator for secondary batteries such as batteries. When microporous polyolefin membranes are used as battery separators, especially when used as lithium ion battery separators, the performance of the membrane has a very strong impact on battery properties, productivity, and safety. Therefore, the microporous polyolefin film needs to have appropriately balanced permeability, mechanical characteristics, dimensional stability, shutdown characteristics, melting characteristics, and the like. Here, the term “balanced” means that optimizing one of these properties does not significantly degrade another property.

  As is well known, separators with a relatively low shutdown temperature and a relatively high melting temperature are required to improve battery safety, particularly for batteries that are exposed to high temperatures during use. Uniform dimensional characteristics, such as film thickness, are essential for high performance films. A separator having high mechanical strength is desirable for a high-performance battery assembly and a battery having high-performance reliability. In order to improve the characteristics of the microporous polyolefin film, it has been proposed so far to optimize the material composition, molding and stretching conditions, heat treatment conditions, and the like.

  In general, microporous polyolefin membranes are substantially composed of polyethylene (i.e., this material is composed solely of polyethylene without significant inclusion of other materials) and has a relatively low melting temperature. have. Therefore, in order to increase the melting temperature, a microporous polyolefin film prepared by mixing polyethylene and polypropylene resins and a multiporous microporous polyolefin film including a polyethylene layer and a polypropylene layer have been proposed. It is difficult to produce a film with uniform dimensional characteristics, such as film thickness, using such a mixed resin or producing a multilayer film having different polyolefin layers. I have to.

  US Patent No. 2,938,201 proposes an extrusion mold for forming a sheet having an adjustable bolt that can be extended and having an adjustable film thickness. The adjustment bolt can be finely adjusted by a heater that controls the length of each bolt between the attachment point in the mold body and the connection point of the mold blade.

  US Patent No. 3,920,365 uses a temperature sensor and a heating element incorporated in the mold to control the thickness distribution of the film by selectively heat-controlling a pair of separated mold lip parts. Propose to do. By partially controlling the temperature change, the local viscosity of the molten polymer material and the local mass flow rate are increased or decreased to maintain the film thickness distribution within an acceptable range.

  In US Patent No. 4,124,342, in order to achieve the required mold gap distribution, that is, the required film thickness distribution, the film thickness is automatically calculated using an algorithm that calculates the rotation speed of each adjusting bolt. Systems have been proposed for automatic control. As can be easily understood, one problem with this system is that it assumes that the response of each of the mold adjustment bolts is all the same.

US Patent No. 4,409,160 proposes a method for controlling the thickness of an extruded and biaxially stretched film product. In this method, the thickness thickness deviation (deviation) is automatically controlled. It has become. In this way, the position along the width direction of the film sheet, to previously obtain the Oh Ida correlation between the position of the adjustment bolt of the extrusion die, initially, before stretching in the transverse direction, the film-like The sheet thickness profile of the sheet is kept within an allowable range, and then the sheet thickness of the film is measured after stretching in the transverse direction. Then, if the deviation (deviation) of the plate thickness is outside the allowable range, the thickness is corrected by sending a signal corresponding to the deviation (deviation) of the film thickness to the corresponding adjustment bolt of the mold I have to.

  In US Patent No. 5,045,264, a composite film composed of one or more second materials embedded in a matrix material on one or both sides of a film, comprising a matrix material and a second material Methods and apparatus have been proposed for producing composite films that are made. The proposed device uses bolts to press the hinged mold lip against the opposite mold lip, thereby creating a gap defined by the two mold lips. Can be narrowed.

  Japanese utility model JP U3048972 proposes an extrusion die for reducing the divergence of the molten polymer flow in the manifold of the extrusion die. In the proposed extrusion mold design, two manifolds are provided to form two slit streams. Molten polymer is fed to the first inlet at the end of the first manifold and the second inlet at the end of the second manifold located opposite the first inlet. ing. The two slit flows are merged inside the mold. It has been theorized that the flow distribution within the mold can be made uniform by preventing the molten polymer flow from diverging in the manifold. Thereby, the uniformity of the plate | board thickness in the horizontal direction of a film or a sheet | seat can be improved.

  JP7-216118A in Japan discloses a battery separator formed of a porous film comprising at least two microporous layers having different polyethylene contents and comprising polyethylene and polypropylene as essential constituent elements. Yes. The polyethylene content is 0 to 20% by weight for one microporous layer, 21 to 60% by weight for the other microporous layer, and 2 to 40% by weight for the entire film. The battery separator has a relatively high shutdown start temperature and mechanical strength.

  In WO 2004/089627, composed of two or more layers, the polypropylene content in at least one surface layer is 50% or more by mass, 95% or more, or less, and the polyethylene content in the entire film is by mass, A microporous polyolefin membrane made from polyethylene and polypropylene, from 50% to 95%, is disclosed.

  WO 2005/113657 discloses a conventional microporous polyolefin film having shutdown characteristics, melting characteristics, dimensional stability, and high-temperature strength characteristics. This membrane is manufactured using a polyolefin composition comprising (a) a composition comprising low molecular weight polyethylene and high molecular weight polyethylene and (b) polypropylene. This microporous polyolefin film is manufactured by a so-called “wet process”.

  Despite the advantages of the prior art as described herein, there remains a strong need for extrusion molds and high quality films or sheets that can produce microporous polyolefin membranes.

The invention disclosed herein relates to an extrusion mold for producing a film or sheet made of a thermoplastic resin material such as a polymer and a diluent. Extrusion mold is
A mold outlet provided with a slot, through which a molten flow of a mixture of polymer and diluent is extruded as a film or sheet, and a first mold lip and a second mold lip Mold outlet consisting of parts,
A supply-side inlet in communication with a supply-side distributor that diverts the polymer and diluent mixture into the first part and the second part;
Consisting of a first mold part with a cross-flow manifold,
The cross flow manifold
(1) a first cross-flow manifold portion that receives a first portion of the mixture, the first passage having a first shaft disposed in a first plane of the extrusion die, and the extrusion die A second axis disposed in the second plane, a second path communicating with the first path, and a third axis disposed in the third plane of the extrusion mold, A third passage that communicates with the second passage, and includes a third passage that communicates with the mold outlet, and a fourth shaft that is disposed in the third plane of the extrusion die. A fourth passage communicating with the passage, the first passage comprising a fourth passage communicating with the mold outlet;
(2) a first passage having a first shaft disposed in a third plane of the extrusion mold, the second crossflow manifold portion receiving a second portion of the mixture of thermoplastic resin materials A second axis disposed in the fourth plane of the extrusion mold, a second path communicating with the first path, and a third axis disposed in the first plane of the extrusion mold A third passage communicating with the second passage, the third passage communicating with the mold outlet, and the fourth shaft disposed in the first plane of the extrusion die. A fourth passage that communicates with the third passage, the fourth passage that communicates with the mold outlet, and a second cross-flow manifold portion .
The first plane and the third plane, and the second plane and the fourth plane are arranged so as to be substantially parallel to each other.

In another aspect, a process is provided for producing a film or sheet made of a mixture of polymer and diluent. This process
Mixing at least one polymer (e.g., a polyolefin composition) and at least one diluent (e.g., a solvent);
Extruding the mixed polymer and diluent through an extrusion mold,
The extrusion mold includes a mold outlet where an extruded material composed of a polymer and a diluent is to be extruded as a film or sheet,
The mold outlet includes a first mold lip portion and a second mold lip portion, and the first mold lip portion has a plurality of cantilever shapes extending vertically from the first mold lip portion. Each of the plurality of cantilever-shaped adjustment members includes a driving means,
The mold outlet further includes a supply-side inlet that communicates with a supply-side distribution section that divides the polymer and diluent mixture into the first part and the second part, and a first mold that includes a cross-flow manifold. It has a part.
The cross flow manifold
(1) a first cross-flow manifold portion that receives a first portion of the mixture, the first passage having a first shaft disposed in a first plane of the extrusion die, and the extrusion die A second axis disposed in the second plane, a second path communicating with the first path, and a third axis disposed in the third plane of the extrusion mold, A third passage that communicates with the second passage, and includes a third passage that communicates with the mold outlet, and a fourth shaft that is disposed in the third plane of the extrusion die. A fourth passage communicating with the passage, the first passage comprising a fourth passage communicating with the mold outlet;
(2) a first passage having a first shaft disposed in a third plane of the extrusion mold, the second crossflow manifold portion receiving a second portion of the mixture of thermoplastic resin materials A second axis disposed in the fourth plane of the extrusion mold, a second path communicating with the first path, and a third axis disposed in the first plane of the extrusion mold A third passage communicating with the second passage, the third passage communicating with the mold outlet, and the fourth shaft disposed in the first plane of the extrusion die. A second cross-flow manifold portion comprising a fourth passage communicating with the third passage and a fourth passage communicating with the mold outlet;
It has.

    The shape memory properties of polymers such as polyolefins have been found to be a factor in maintaining the thickness uniformity of the film or sheet exiting the extrusion die. Conventionally, it has been observed that a shape memory effect is produced when a sheet or film is extruded or coextruded. The extruded material such as a sheet or a film formed from the molten polymer contains a small amount of a small amount of solvent. Therefore, it contains a large amount of solvent in the range of 10% by weight or more, 25% by weight or more, 50% by weight or more, or 75% by weight or more, based on the weight of the extruded material. It was surprising that a shape memory effect appeared in the polymer extrusion.

  It was also found that the extrusion die manifold design is affected by shape memory characteristics. In the form illustrated here, the one or more crossflow manifolds are adapted to provide a flow path that is long enough to substantially reduce the shape memory characteristics of the extruded material.

  Further, in another form disclosed herein, each of the first and second crossflow manifold portions of the crossflow manifold traverses over a length at least twice the width of the extrusion mold. A flow path is provided.

  Further, in another embodiment disclosed herein, the first mold lip portion includes a plurality of cantilever-shaped adjustment members extending vertically from the first mold lip portion, and the plurality of cantilevers. Each of the beam-shaped adjusting members is provided with driving means.

  Further, in another form disclosed herein, each of the driving means includes an individual lip bolt so that the width of the mold outlet in the region adjacent to each adjustment member can be changed.

  The above, or other advantages, features, and characteristics of the extrusion mold disclosed herein, and effective application methods and / or methods of use thereof, in particular, will be described in detail below. It will become clear by referring to the figures attached here.

FIG. 1 shows an exploded perspective view of an extrusion mold equipped with a cross-flow manifold system for producing a film or sheet of a thermoplastic resin material. FIG. 2 shows a part of an exploded perspective view of an extrusion mold provided with the cross flow manifold system shown in FIG. 1, and shows a pair of end face plates arranged in the mold. FIG. 3 shows an outline of an extrusion die for producing a film or sheet of a thermoplastic resin material having a multilayer structure, and shows individual flow paths of the thermoplastic resin material. FIG. 4 is a perspective view showing a first part of a crossflow manifold for producing a surface layer of a film or sheet having a multilayer structure of thermoplastic resin materials. FIG. 5 is a perspective view showing a second portion of a cross flow manifold for producing a surface layer of a film or sheet having a multilayer structure of thermoplastic resin materials. FIG. 6 shows a schematic view of a co-extrusion mold for producing a multilayer film or sheet of thermoplastic resin material, and shows a flow path of the surface layer of the thermoplastic resin material. is there. FIG. 7 shows a perspective view of an extrusion mold for producing a film or sheet of a thermoplastic resin material, and shows an adjustment system of a cantilever-shaped mold lip portion. FIG. 8 shows a mold exit front view of an extrusion mold for producing a film or sheet of a thermoplastic resin material, and shows a cantilever-shaped mold lip adjustment system. It is. FIG. 9 shows a perspective view of an extrusion mold for producing a film or sheet of a thermoplastic resin material, and shows a cantilever-shaped mold lip adjustment system having a driving means. It is a thing. FIG. 10A shows a simplified adjustment system for a cantilever-shaped mold lip portion provided with a driving means. FIG. 10B shows a simplified adjustment system of a cantilever-shaped mold lip portion provided with a driving means. FIG. 11 is a perspective view of a coat hanger type extrusion die, and shows a flow path of a thermoplastic resin material. FIG. 12 is a perspective view of a cross-flow extrusion mold and shows a flow path of a thermoplastic resin material.

  Hereinafter, a description will be given with reference to FIG. 1-12. In these drawings, the same parts are denoted by the same reference numerals.

  First, FIG. 1-3 shows an extrusion die 10 for producing a film or sheet of a thermoplastic material. The extrusion mold 10 is provided with a mold outlet 12, through which the mixture of polymer and diluent is extruded as a film or a sheet. In one form, the extrusion mold 10 is provided with a first mold part 14, a second mold part 16, and a third mold part 18, and further the first mold part. 14, a cross flow manifold 20 is provided that is disposed across a plurality of passages formed in the second mold part 16 and the third mold part 18. As can also be seen from the figure, the machine of the crossflow manifold 20 by using an extrusion mold 10 having a first mold part 14, a second mold part 16, and a third mold part 18. Processing and cleaning can be performed easily.

  As shown in detail in FIG. 1, the cross-flow manifold 20 has a supply-side inlet 22 and a supply-side distributor 24 for supplying polymer to a plurality of passages of the cross-flow manifold 20 communicating with the mold outlet 12. Is provided. During operation, the feed stream F of the polymer and diluent mixture is distributed into a first feed stream S1 and a second feed stream S2. Then, the first supply flow S1 flows to the first cross flow manifold portion 26, and the second supply flow S2 flows to the second cross flow manifold portion 28.

  The first mold portion 14 is provided with a first side surface 30, a second side surface 32, a first end surface 34, and a second end surface 36, and these surfaces have the cross flow manifold 20 Each part is provided. The second mold portion 16 is provided with an inner side surface 38, the third mold portion 18 is provided with an inner side surface 40, and each portion of the cross flow manifold 20 is provided on these surfaces. In addition, as can be assumed from FIG. 2, the first end face plate 42 and the second end face plate 44 are also provided with respective portions of the cross flow manifold 20.

  In one form, the first cross-flow manifold portion 26 includes a first plane 50 formed between the first side 30 of the first mold portion 14 and the inner side 38 of the second mold portion 16. Formed between the first passage 26a with the first shaft disposed therein, the first end face 34 of the first mold portion 14 and the first end face plate 42 (see FIG. 2). A second passage 26b with a second axis disposed in the second plane 52, a second side 32 of the first mold part 14 and an inner side 40 of the third mold part 18. And a third passage 26c having a third shaft disposed in a third plane 54 formed therebetween. As can be assumed from FIG. 1, a part of the flow of the polymer / diluent mixture flows directly downward from the third passage 26c. And a fourth shaft disposed in a third plane 54 formed between the second side surface 32 of the first mold part 14 and the inner side surface 40 of the third mold part 18 It balances across the fourth passage 26d.

  Similarly, the second crossflow manifold portion 28 is within a third plane 54 formed between the second side 32 of the first mold portion 14 and the inner side 40 of the third mold portion 18. A first passage 28a having a first shaft disposed therein, a fourth passage formed between the second end face 36 of the first mold part 14 and the second end face plate 44 (see FIG. 2). Between the second passage 28b with a second axis disposed in the plane 56 of the first mold portion 14, the first side surface 30 of the first mold portion 14 and the inner side surface 38 of the second mold portion 16. And a third passage 28c having a third axis disposed in the formed first plane 50. As can be assumed from FIG. 1, a part of the flow of the polymer / diluent mixture flows directly downward from the third passage 28c. And a fourth shaft disposed in a first plane 50 formed between the first side face 30 of the first mold part 14 and the inner side face 38 of the second mold part 16. The fourth passage 28d is crossed and balanced.

  In one form, each of the first cross-flow manifold portion 26 of the cross-flow manifold 20 and the second cross-flow manifold portion 28 of the cross-flow manifold 20 includes pressure manifolds 26e and 28e respectively communicating with the mold outlets. .

  As shown in the figure, in one embodiment, the first plane and the third plane, and the second plane and the fourth plane are arranged substantially in parallel. As used herein, “substantially parallel” means that the surfaces facing each other (that is, the first plane and the third plane, and the second plane and the fourth plane) are extrusion molds. This means that there is no crossing inside the outer contour.

  Alternatively, the extrusion mold 10 includes a second mold portion 124 for producing the first skin layer. As shown in detail in FIGS. 4 and 5, the second mold portion 124 includes a cross-flow manifold 126. As can be seen from FIGS. 4 and 5, the cross-flow manifold 126 has a flow path 128 that traverses the second mold part 124 over a length that is at least twice the width of the second mold part 124. It has. The cross flow manifold 126 further includes a pressure manifold 132 communicating with the supply side inlet 130 and the mold outlet 12.

  In still another embodiment, if a three-layer film or sheet is required, a third mold portion 124 for producing the second skin layer may be provided. The third mold portion 124 can also include a crossflow manifold 126. As with the second mold part 124, the crossflow manifold 126 of the third mold part 124 has a length of at least twice the width of the third mold part 124. A flow path 128 is provided that traverses the mold portion 124. The cross flow manifold 126 of the third mold part 124 includes a pressure manifold 132 communicating with the supply side inlet 130 and the mold outlet 12.

  In particular, as shown in FIG. 6, the coextrusion mold 10 is used to distribute the polymer and diluent feed streams for producing the skin layer into the first feed stream S1 and the second feed stream S2. The skin layer supply block 146 may be provided. Then, the first supply flow S1 flows into the supply-side inlet 130 of the second mold part 124 for producing the first skin layer, and the second supply flow S2 passes through the second skin layer. It flows into the supply side inlet 130 of the third mold part 124 for manufacturing.

  In another embodiment, when a two-layer film or sheet is manufactured, the coextrusion mold 10 includes a supply side inlet of the second mold portion 124 for manufacturing the first skin layer. A skin layer supply block (not shown) through which the polymer flows into 130 is provided. Additional mold parts (and supply side inlets) can be placed between the mold parts forming the outer (skin) layer of the membrane. In this way it is possible to extrude membranes with four or more independently configurable layers.

  As will be described later, when a microporous film-like film or sheet is formed from a polymer (for example, polyolefin or the like), an inherent property relating to shape memory is shown as a characteristic of these materials. Other films and sheets formed from other thermoplastic resins similarly exhibit such characteristics. As is known in the art, shape memory plastics have two phases: a thermoplastic phase and a freezing phase. The initial shape is memorized in the freezing phase and has the shape memory effect of returning from its shape to its original shape even if the plastic is deformed to a temporary shape. As is well known, the polymer chain of the polymer has an ideal three-dimensional shape (Gaussian coil) in solution in the molten state or in the unperturbed state. For example, when the polymer is deformed by an external force such as a shear flow, the polymer shape is relaxed by expanding the polymer in the axial direction of the polymer, and the ideal Gaussian coil state is restored. This relaxation time is strongly dependent on the number of entanglements. Therefore, the longer the relaxation time is required, the higher the molecular weight of the polymer and the higher the polymer concentration in the solution.

  The coextrusion mold 10 also includes a second mold portion 24 for producing the first skin layer. As can be seen with reference to FIGS. 3 and 4, the second mold portion 24 includes a crossflow manifold 26. As can be seen from these figures, the cross flow manifold 26 has a melt flow of thermoplastic material passing through the second mold part 24 over a length that is at least one times the width of the second mold part 24. You may provide the flow path 28 made to cross. The cross flow manifold 26 also includes a pressure manifold 32 communicating with the supply side inlet 30 and the mold outlet 12.

  In another form, each of the crossflow manifold portion 26 and the crossflow manifold portion 28 of the crossflow manifold 20 traverses the extrusion mold 10 over a length that is at least twice the width of the extrusion mold 10. The flow path is provided.

  In another form, each of the cross-flow manifold 126 of the second mold portion 124 and the cross-flow manifold 126 of the third mold portion 124 is a shape memory property of the polymer present in the polymer and diluent mixture. Is provided with a sufficiently long channel. In another form, when producing a two-layer film or sheet, the cross-flow manifold 126 of the second mold section 124 can substantially eliminate the shape memory characteristics of the extruded product. It has a sufficiently long channel.

  In yet another form, each of the crossflow manifold 126 of the second mold portion 124 and the crossflow manifold 126 of the third mold portion 124 is at least 2.5 times the full width of the second mold portion 124. A flow path substantially traversing the length and a flow path substantially traversing the length of at least 2.5 times the full width of the third mold part 124, respectively. In yet another form, when producing a two-layer film or sheet, the crossflow manifold 126 of the second mold portion 124 is at least 2.5 times as long as the entire width of the second mold portion 124. A flow path that substantially crosses over.

  Next, referring to FIG. 7-9, the mold outlet 12 of the extrusion mold 10 may be provided with a first mold lip part 46 and a second mold lip part 48, The mold lip portion 46 includes a plurality of cantilever-shaped adjusting members 60 extending vertically from the first mold lip portion 46. As can be assumed from the drawing, the plurality of cantilever-shaped adjusting members 60 are formed so as to be able to rotate around an axis 66. Each of the plurality of cantilever-shaped adjusting members 60 includes a driving means 62.

  As shown in FIG. 9, each driving means 62 is provided with an individual lip bolt 64 so that the width of the mold outlet 12 in the region adjacent to each adjusting member can be changed. Each lip bolt 64 is threaded over the base plate 68 to the bolt tip 72. An adjustment pad 74 is disposed at the tip position 76 of each of the plurality of cantilever-like adjustment members 60 so as to come into contact with the bolt tip 72.

  Conveniently, the cantilever-shaped mold lip adjustment system disclosed herein has a function that allows the width of the mold gap to be locally and finely adjusted. By this function, the variation in the lateral direction of the thickness of the film or sheet can be remarkably reduced, and an extremely high quality film or sheet can be provided. For example, in a conventional mold lip adjustment system, lip bolts are typically arranged at intervals of 36 mm along the lateral direction (width direction) of the mold outlet. The pattern (thickness) in the lateral direction (width direction) of the film can be adjusted at intervals of about 180 mm. As can be understood from the above, it has been extremely difficult to finely adjust the thickness of the film in such a conventional mold lip adjustment system.

  In the cantilever-shaped mold lip adjustment system disclosed herein, the distance between the lip bolts is reduced to about 12 mm, which corresponds to a product width of about 60 mm. As can be seen from the figure, in the conventional design, if the gap between the lip bolts is simply shortened, the lip bolt needs to be thinned accordingly, and as a result, the rigidity of the lip bolt is reduced. There has been a problem that the function of accurately adjusting the width of the gap is degraded.

  Referring to FIGS. 10A and 10B, it can be seen that the cantilevered mold lip adjustment system disclosed herein utilizes the “lever principle”. Such a large torsional moment can be generated even when the distance between the lip bolts 64 is narrow. The control force of the lip portion of the mold is made sufficient by changing the torsional moment of the vertical component that deforms the lip portion. Further, the deformation of the first mold lip 46 due to the pressure from the inside of the extrusion mold 10 does not occur. Eventually, the stress generated at the connection between the base plate 68 of the main frame and the first mold lip 46 is reduced compared to other designs.

  It was found that the thickness of the film or sheet can be controlled very well by operating the cantilever-shaped mold lip adjustment system disclosed herein (the thickness variation in the lateral direction of the film or sheet is About ± 0.5μ). Furthermore, in the cantilever-shaped mold lip adjustment system disclosed here, it was confirmed that the thickness of the film can be adjusted at intervals of 50 mm.

  Even if heat is dissipated from around the first mold lip 46 and the second mold lip 48, this problem can be solved by using an insulating material.

  The extrusion mold and manifold system disclosed herein presents difficulties in extruding a polyolefin solution from a mold in a variety of processes, including the process of forming a “wet”, microporous polyolefin film or sheet. Can solve various problems. As shown in FIG. 11, the difficult problem here is that the mold 200 with a coat hanger type manifold is used to extrude a single layer microporous polyolefin film or sheet 202. When used, due to the shape memory effect produced in the extruded material, the plate thickness becomes non-uniform in the lateral direction of the extruded material. As can be appreciated, the shape memory effect in the extruded material tends to act in a direction perpendicular to the flow S in the mold manifold 204 of the mixed polymer and diluent solution (eg, polyolefin solution). In the mold 200 provided with the coat hanger type manifold, the main direction of the flow in the manifold is directed toward the mold lip 206, so that the shape memory effect is likely to occur in the lateral direction of the extruded material. For this reason, redistribution of the material in the extruded material occurs, and the material tends to gather in the central direction along the lateral direction of the extruded material.

  Referring now to the single layer extrusion mold shown in FIG. 12, this problem can be solved by using a mold 300 with a crossflow manifold. Here, the polyolefin solution S crosses the entire width of the mold manifold 304 before the polyolefin solution S approaches the mold lip 306. As can be understood, by doing so, most of the polyolefin solution S in the manifold portion of the mold flows parallel to the mold lip 306. As a result, the shape memory effect mainly occurs in the machine direction (longitudinal direction), and a more uniform plate thickness distribution can be obtained in the lateral direction of the extruded material.

  As described above, the extrusion mold disclosed herein is useful when forming a film or sheet of a microporous polyolefin film. These films and sheets are used particularly in the severe environment of battery separators. The multilayer films described below are manufactured using a manifold system using the principle of coextrusion molds and cross flow manifolds, or using a manifold system for manufacturing single layer molds and single layer films or sheets. Furthermore, it can be manufactured by a method in which another layer is additionally laminated on the single layer using a conventional technique.

  In one form, the multi-layer, microporous membrane is composed of two layers. The first layer (e.g., membrane skin layer, outer layer, upper layer) is made of the material of the first microporous layer, and the second layer (e.g., membrane bottom layer, lower layer, core layer) is And made of the material of the second microporous layer. For example, when viewed from above the axis approximately perpendicular to the lateral and longitudinal (mechanical) directions of the membrane, the membrane can see a flat upper layer and the flat bottom layer of the membrane is hidden behind the upper layer and cannot be seen. . The extrusion mold described here is a single layer microporous membrane, for example a single layer polyethylene microporous membrane and / or PCT International Publication No. WO2007 / 132942 (hereby incorporated by reference) It is also useful in the production of single layer polyolefin membranes disclosed in (which form part of this specification).

  As another form, in the case of a multi-layered microporous film having three or more layers, the outer layer (or surface layer or skin layer) is made of the material of the first microporous layer. The at least one core side layer or intermediate layer is made of the material of the second microporous layer. A related form is a multi-layer, microporous polyolefin film, in a two-layer film, the first layer is made of the material of the first microporous layer, and the second layer is the second layer. The material of the microporous layer. Further, as a related form, in the case of a multi-layered, microporous polyolefin film comprising three or more layers, the outer layer is made of the material of the first microporous layer, and at least One intermediate layer is made of the material of the second microporous layer. Such membranes are described in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389. And by quoting these publications here, these publications form a part of this specification.

The starting materials useful for the production of the aforementioned film or sheet are described below. Suitable polymers, solvents and their amounts are described, for example, in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389. As will be appreciated by those skilled in the art, the choice of starting material is not critical as long as a manifold system utilizing the principles of extrusion molds and crossflow manifolds is used. In one form, the material of the first and second microporous layers includes polyethylene. In one form, the material of the first microporous layer includes a first polyethylene (PE-1) having an Mw value of about 1 × 10 ⁶ or less or a second having an Mw value of at least about 1 × 10 ⁶ . Of polyethylene (UHMWPE-1). In one form, the material of the first microporous layer includes first polypropylene (PP-1). In one form, the material of the first microporous layer is (1) polyethylene (PE), (2) ultra high molecular weight polyethylene (UHMWPE), (3) PE-1 and PP-1, (4) PE- 1, composed of either UHMWPE-1 or PP-1.

(2) and (4) In one embodiment, UHMWPE preferably has an Mw value in the range of about 1 x 10 ⁶ to about 15 x 10 ⁶ , or in the range of about 1 x 10 ⁶ to about 5 x 10 ⁶ More desirable are those having an Mw value of about 1 x 10 ⁶ to about 3 x 10 ⁶ . In order to obtain a microporous layer having a hybrid structure as described in PCT International Publication No. WO2008 / 016174, UHMWPE-1 is about 1% by weight with respect to the total amount of PE-1 and UHMWPE-1. % Or more is more desirable, or more preferably about 15% to about 40% by weight, and may be at least either a homopolymer or a copolymer. In one embodiment of the above (3) and (4), PP-1 may be at least either a homopolymer or a copolymer, and about 25% by weight or less based on the total amount of the material of the first microporous layer. The content of is desirable. In one form, the Mw value of the polyolefin in the material of the first microporous layer may be about 1 × 10 ⁶ or less to obtain a microporous layer having a hybrid structure as defined later. It may range from about 1 × 10 ⁵ to about 3 × 10 ⁶ , or from about 2 × 10 ⁵ to about 3 × 10 ⁶ . In one form, PE-1 preferably has an Mw value in the range of about 1 x 10 ⁴ to about 5 x 10 ⁵ , or an Mw value in the range of about 2 x 10 ⁵ to about 4 x 10 ^5. What it has is further desirable. It may be one or more of high density polyethylene, medium density polyethylene, branched low density polyethylene, or linear low density polyethylene, and may be at least either a homopolymer or a copolymer.

In one form, the material of the second microporous layer is (1) a fourth polyethylene (UHMWPE-2) having an Mw value of at least about 1 × 10 ⁶ , and (2) an Mw value of 1 × 10 ⁶ or less. The third polyethylene and UHMWPE-2, as well as the fourth polyethylene, wherein the fourth polyethylene comprises at least about 8% by weight based on the total weight of the third polyethylene and the fourth polyethylene; 3) Consists of one of UHMWPE-2 and PP-2, (4) PE-2, UHMWPE-2, and PP-2. In the forms of (2), (3), and (4) described above, UHMWPE-2 is used to produce a microporous polyolefin film that is a relatively strong multilayer material. And at least about 8%, alternatively at least about 20%, alternatively at least about 25% by weight relative to the total amount of PP-2. In the above forms (3) and (4), PP-2 may be at least either a homopolymer or a copolymer, and is 25% by weight or less based on the total amount of materials of the second microporous layer, Alternatively, an amount in the range of about 2% to about 15% by weight, or in the range of about 3% to about 10% by weight can be included. In one embodiment, preferred PE-2 can be the same as PE-1, but can also be selected independently. In one embodiment, preferred UHMWPE-2 can be the same as UHMWPE-1, but can also be selected independently.

In addition to the first, second, third, fourth polyethylene and the first, second polypropylene, each of the first and second layer materials may optionally include one or more added polyolefins, And / or polyethylene wax (eg, having a Mw value in the range of about 1 × 10 ³ to about 1 × 10 ⁴ as described in US2008 / 0057388).

  In one form, a process for producing a two-layer microporous polyolefin membrane is provided, in which an extrusion mold and manifold system of the type disclosed herein is used. In another form, the microporous polyolefin membrane has at least a three-layer construction and is manufactured using an extrusion mold and manifold system of the type disclosed herein. The production of a microporous polyolefin film will be described mainly as a film having a two-layer structure and a three-layer structure.

  In one embodiment, the microporous polyolefin film having a three-layer structure is provided between the first and third microporous layers forming the outer layer of the microporous polyolefin film and the first and third layers (optional). And a second layer (core layer) disposed in contact with the substrate. In another form, the first layer and the third layer are made from a first polyolefin solution and the second layer (core layer) is made from a second polyolefin solution.

In one embodiment, a method for producing a microporous polyolefin film having a multilayer structure is provided. The manufacturing method is
(1) To prepare a first mixture of polyolefin and diluent (first polyolefin solution), a first polyolefin composition and at least one diluent (e.g., a film-forming solvent) (e.g., melted) Mixing (by blending);
(2) To prepare a second mixture of polyolefin and diluent (second polyolefin solution), a second polyolefin composition and at least a second diluent (for example, a second film-forming solvent) Mixing, and
(3) extruding first and second polyolefin solutions from at least one mold of the type disclosed herein to form a multi-layer extruded material;
(4) optionally cooling the multi-layered extruded material to form a cooled extruded material;
(5) removing at least a portion of the film-forming solvent from the extruded or cooled extruded material to form a multilayered film;
(6) Preferably, the method includes a step of removing at least a volatile substance from the multi-layered film.
The step (7) of stretching the optional extruded material and the step (8) of treating the optional extruded material with a heated solvent are performed between steps (4) and (5) if necessary. After step (6), optionally stretching (9) a multi-layered microporous film, optionally heat-treating the multi-layered microporous film (10), and optionally ionizing radiation The step (11) of crosslinking by, the step (12) of hydrophilic treatment as an option, etc. can be carried out.

  The first polyolefin composition is composed of a polyolefin resin as described above and is mixed with a suitable film forming solvent, for example, by dry mixing or melt blending, to create a first polyolefin solution. As an option, for example, as disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389, the first polyolefin solution may include one or more antioxidants, silicate fine powder ( An additive such as a pore forming material may also be included.

  The first and second diluents can be solvents that are in a liquid state at room temperature. Suitable diluents are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

In one form, the resin or the like used to produce the first polyolefin composition is melt blended in an extruder or blender using two screw members. For example, conventionally used extruders (or blenders and blender-extruders), such as an extruder using two screw members, use a resin or the like to form the first polyolefin composition. Can be used when mixing. Diluents can be added to the polyolefin composition (or the resin used to create the polyolefin composition) at a convenient point in the process. For example, in one form, the first polyolefin composition and the first diluent (film forming solvent) are melt blended and the solvent is
(1) Before starting melt blending,
(2) During melt blending of the first polyolefin composition, or
(3) Can be added to the polyolefin composition (or its components) at any stage after melt blending. And this is, for example, melt blended or partially melt blended in a region located downstream of the extruder used to melt blend the polyolefin composition or in a second extruder. The first film-forming solvent is supplied to the polyolefin composition.

  Suitable methods for blending the polymer and diluent are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  The amount of the first polyolefin composition in the first polyolefin solution is not critical. In one form, the amount of the first polyolefin composition in the first polyolefin solution can range from about 1 wt% to about 75 wt%, for example, about 1 wt%, based on the weight of the polyolefin solution. It may be in the range of 20 wt% to about 70 wt%. The remaining part of the polyolefin solution is solvent. For example, the polyolefin solution may include from about 30% to about 80% by weight solvent (or diluent) based on the weight of the polyolefin solution.

  The second polyolefin solution can be prepared by the same method used in preparing the first polyolefin solution. For example, the second polyolefin solution can be prepared by melt blending the second polyolefin composition and the second film-forming solvent.

  The amount of the second polyolefin composition in the second polyolefin solution is not critical. In one form, the amount of the second polyolefin composition in the second polyolefin solution can range from about 1 wt% to about 75 wt%, based on the weight of the second polyolefin solution, For example, it may be in the range of about 20 wt% to about 70 wt%. The remaining part of the polyolefin solution is solvent. For example, the polyolefin solution may include from about 30% to about 80% by weight solvent (or diluent) based on the weight of the polyolefin solution.

  Conveniently, an extrusion die of the type disclosed herein is used to form an extrusion that can be coextruded or laminated. As one form, the extrusion metal mold | die which can be arrange | positioned in parallel or arrange | positioned together is used in order to form a some extrusion material. The first and second sheet molds are connected to the first and second extruders, respectively. Here, the first extruder is provided with the first polyolefin solution, and the second extruder is provided with the second polyolefin solution. While not critical, when laminating, it is generally easy to do laminating when the extruded first and second polyolefin solutions are still near the extrusion temperature.

  In another form, first, second, and third molds are connected to the first, second, and third extruders. Here, the first and third molds are provided with the first polyolefin solution, and the second mold is provided with the second polyolefin solution. In this form, the laminated extruded material is formed to constitute two outer layers made of the extruded first polyolefin solution and one intermediate layer made of the extruded second polyolefin solution.

  In yet another form, first, second, and third molds are connected to the first, second, and third extruders. Here, the second mold includes the first polyolefin solution, and the first and third molds include the second polyolefin solution. In this form, the laminated extruded material is formed to constitute two outer layers composed of the extruded second polyolefin solution and one intermediate layer composed of the extruded first polyolefin solution.

  In general, the gap size of the mold is not particularly critical. For example, an extrusion mold of the type disclosed herein can have a mold gap dimension between about 0.1 mm and about 5 mm. Mold temperature and extrusion rate are also non-critical parameters. For example, during extrusion, the mold temperature can be heated to be in the range of about 140 ° C to about 250 ° C. The extrusion rate can be, for example, in the range of about 0.2 m / min to about 15 m / min. The thickness of the layer of the extruded material having a laminated structure can be set independently. For example, the sheet finally obtained can have a relatively thick skin layer or surface layer compared to the thickness of the intermediate layer of the extruded material having a laminated structure.

  Optionally, the multi-layer extrusion can be cooled. The cooling rate and cooling temperature are not particularly critical. Suitable cooling methods are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  In one form, at least the first and second film-forming solvents are removed from the multilayered extruded material to form a multilayered microporous film. Suitable solvent (diluent) removal methods are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389. For example, a cleaning solvent is used.

  In one form, at least volatile material (eg, cleaning solvent) left on the film is removed. Suitable methods for removing volatile materials are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  Prior to the step for removing the film-forming solvent, the extruded material can be stretched to obtain an extruded material with directionality. Methods for drawing extruded or cooled extruded materials are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  Although not required, the extruded material can be treated with a high temperature solvent as disclosed in PCT International Publication No. WO2000 / 20493.

  As one form, the microporous film can be stretched in at least one axial direction after removing at least the diluent. The selected stretching method is not critical and conventional stretching methods such as the tenter method can be used. As described herein, when the extruded material is stretched, stretching a microporous polyolefin film in a dry state is called dry stretching, re-stretching, or dry orientation. Appropriate stretching methods are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  The amount of stretching when stretching is not a critical issue. For example, the amount of stretch of the microporous membrane can range from about 1.1 to about 2.5, or from about 1.1 to about 2.0, in at least one in-plane direction. Biaxial stretching is also possible, and in this case, the amount of stretching need not be symmetrical (the same for each axis).

  In one form, the microporous film can be heat treated and / or annealed. Microporous membranes can be cross-linked if necessary (eg, by irradiation with ionizing radiation such as a-rays [3-rays, 7-rays, electron beams, etc.]). Further, a hydrophilic treatment can be applied to the microporous membrane. (That is, this hydrophilic treatment makes the microporous olefin membrane more hydrophilic. [Eg, monomer affinity treatment, surfactant treatment, corona discharge treatment, etc.]) Heat treatment of membrane, annealing, Suitable methods for treatments such as crosslinking are disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  In addition, the microporous film manufacturing method disclosed in PCT International Publication No. WO2008 / 016174 (multilayer film) and No. WO2007 / 132942 (single layer film) can also be used.

  Although the extrusion process has been described in terms of manufacturing a two-layer or three-layer extrusion material, the extrusion process is not limited to these. For example, a plurality of molds and / or mold assemblies can be manufactured by applying the extrusion mold principle described here and the method described herein to produce a multi-layer extruded material having four or more layers. Can be used to A method for producing a microporous membrane as disclosed in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389 can also be applied to the present invention. Quoted here

  All patents, test procedures, and other documents cited herein, including the document on which priority is claimed, are hereby incorporated by reference in their entirety to the extent they are not contradictory. And this should be allowed in all jurisdictions.

  Although the embodiments disclosed herein have been described as specific, it is possible for those skilled in the art to make various improvements without departing from the technical idea of the present invention. It is self-evident and it can be easily implemented. Therefore, the scope of claims (claims) attached to the present specification is not limited to the examples and descriptions described in the present specification. It should be construed as including all the patentable novel technical features described therein, and all such technical features shall be deemed equivalent by those skilled in the art to which this invention belongs. Should be handled.

  In this specification, when an upper limit numerical value and a lower limit numerical value are described, it is intended to include a range from the lower limit to the upper limit.

Claims (8)

An extrusion mold for producing a thermoplastic resin extrusion material from a mixture of a polymer and a diluent,
(1) A mold outlet in which a melt flow of a thermoplastic resin is extruded as a film or sheet, and a mold outlet comprising a first mold lip portion and a second mold lip portion;
(2) a supply-side inlet communicating with a supply-side distributor that diverts the mixture into the first part and the second part;
(3) A first mold part provided with a crossflow manifold, the crossflow manifold being
(a) a first cross-flow manifold portion that receives a first portion of the mixture, the first passage having a first shaft disposed in a first plane of the extrusion mold, and the extrusion die A second axis disposed in the second plane of the mold, a second path communicating with the first path, and a third axis disposed in the third plane of the extrusion mold A third passage in communication with the second passage, the third passage in communication with the mold outlet, and a fourth shaft disposed in the third plane of the extrusion die, A first cross-flow manifold portion comprising a fourth passage communicating with the passage of the first passage and a fourth passage communicating with the mold outlet;
(b) a second cross-flow manifold portion that receives a second portion of the mixture, the first passage having a first axis disposed in a third plane of the extrusion mold, and the extrusion die A second axis disposed in the fourth plane of the mold, a second path communicating with the first path, and a third axis disposed in the first plane of the extrusion mold A third passage in communication with the second passage, the third passage in communication with the mold outlet, and a fourth shaft disposed in the first plane of the extrusion die, A second cross-flow manifold portion comprising a fourth passage communicating with the passage of the first passage and a fourth passage communicating with the mold outlet;
A first mold part configured to comprise :
The extrusion mold, wherein the first plane and the third plane, and the second plane and the fourth plane are arranged so as to be substantially parallel to each other . 2. The extrusion die according to claim 1, wherein each of the first crossflow manifold portion of the crossflow manifold and the second crossflow manifold portion of the crossflow manifold is at least twice the width of the extrusion die. An extrusion mold comprising a flow path traversing the length . 3. The extrusion mold according to claim 2 , wherein the first crossflow manifold portion further includes a fifth passage communicating with a fourth passage and communicating with the die outlet. The manifold part further includes a fifth passage communicating with the fourth passage and communicating with the mold outlet. The extrusion mold according to claim 1,
(4) a second mold part for producing the first surface layer, the second mold part comprising a cross flow manifold, the cross flow manifold being the width of the second mold part The cross flow manifold includes a pressure manifold that communicates with a supply side inlet and the mold outlet. An extrusion mold, further comprising a second mold part. The extrusion mold according to claim 4 ,
(5) a third mold part for producing a second surface layer, the third mold part comprising a crossflow manifold, the crossflow manifold being the width of the third mold part The cross flow manifold includes a pressure manifold that communicates with a supply side inlet and the mold outlet. An extrusion mold, further comprising a third mold part. 6. The extrusion mold according to claim 5 , wherein each of the second mold part cross-flow manifold and the third mold part cross-flow manifold includes a second mold part and a third mold part. An extrusion die comprising a flow path that traverses in a substantially transverse direction over a length that is at least 2.5 times the length in the width direction. 7. The extrusion mold according to claim 1 , wherein the first mold lip portion includes a plurality of cantilever-shaped adjustment members extending vertically from the first mold lip portion. An extrusion die, wherein each of the plurality of cantilever-shaped adjusting members includes a driving means. 8. The extrusion mold according to claim 7 , wherein each of the driving means includes an individual lip bolt, and the individual lip bolt can change a width of a mold outlet in a region adjacent to each adjustment member. Extrusion mold characterized by.

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