JP2010538858A - Coextrusion mold and its manifold system - Google Patents

Abstract

The present invention relates to a coextrusion mold for producing a multilayer film or sheet made of a thermoplastic resin material. The co-extrusion mold includes a mold outlet, a first mold part for manufacturing the core layer, and a second mold part for manufacturing the first surface layer, the second mold part The mold part has a cross-flow manifold, which is a flow path in which a part of the melt flow of the thermoplastic material traverses more than 1 times the width of the second mold part. A second mold part comprising: a third mold part for producing a second surface layer, the third mold part having a cross-flow manifold, the cross-flow The manifold is composed of a third mold part having a flow path in which a part of the melt flow of the thermoplastic material crosses over at least one times the width of the third mold part. ing.

[Selection] Figure 1

Description

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

  Coextrusion molds are used in the manufacturing process to make various products. For example, certain extrusion molds are used to form plastic materials into thin films, sheets, or extended shapes. Many advantages can be realized by producing a film in which thin films are stacked in multiple layers. This is because a film having such a structure can combine properties that cannot be achieved by a film having a single layer structure. Originally, such multi-layered products were made by laminating separately formed films or sheets together with adhesive, heat, or pressure.

  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. As can be easily understood, if the viscosity, temperature, and flow rate are greatly different between the molten resins forming the resin layer, it is difficult to obtain a multilayered sheet having a uniform thickness. .

  A mold system having a plurality of manifolds with individual flow paths and manifolds for each layer is designed, and the layers are usually in contact immediately before exiting the mold. Since the layers meet in the vicinity of the final mold exit slot, materials with somewhat different rheological properties can be processed. Each layer can be formed with a desired thickness before being combined with other layers, and by adjusting the flow rate of each layer, the flow uniformity among multiple layers can be effectively maintained. . If the flow of each layer is different at the point where the layers merge, a non-uniform portion is generated in the product, and thus the above discussion is necessary.

  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, the central feed mold is a teardrop-shaped flat manifold (this flat manifold may be in the form of a coat hanger-like manifold), 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. However, once the initial adjustment is made (that is, when the movable lip portion moves from the original adjustment position), it is not easy, if possible, to return to the original position. In addition, when the mold is not clean and no special tool is used, the extrusion gap of the flexible mold that is used industrially and standardly is accurately adjusted to a predetermined gap dimension. It is impossible.

  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.

  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 polyethylene resin 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”.

  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.

  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.

  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.

  Despite the advantages of the prior art described here, there is still a strong need for coextrusion molds and manifold systems and high quality multilayer films that can produce microporous polyolefin membranes.

The invention disclosed herein relates to a coextrusion mold for producing a multilayer film or sheet made of a thermoplastic resin material. The coextrusion mold is
A mold outlet through which a layered mixture of polymer and diluent is extruded as a multilayer film or sheet;
A first mold part for producing a core layer, wherein the first mold part has a flat manifold, and the manifold communicates with a mold outlet provided with a supply side inlet and a slot. A first mold part having a pressure manifold;
A second mold part for producing a first surface layer, the second mold part having a crossflow manifold, the crossflow manifold having one flow path, and a polymer; A portion of the diluent mixture traverses more than one time the width of the second mold part, and the crossflow manifold communicated with a mold inlet with a supply inlet and a slot. A second mold part having a pressure manifold and a third mold part for producing a second surface layer, wherein the third mold part has a cross flow manifold, the cross flow manifold Has a single flow path so that a portion of the polymer / diluent mixture traverses more than one time the width of the third mold part and the cross-flow manifold is connected to the supply side inlet And slot A third mold part having a pressure manifold in communication with the mold outlet,
It has.

In another aspect, a process is provided for producing a multilayer film or sheet of thermoplastic resin. This process
Mixing at least a first polyolefin composition and at least a first solvent to prepare a first polyolefin solution;
Mixing at least a second polyolefin composition and at least a second solvent to prepare a second polyolefin solution;
Extruding the first polyolefin solution and the second polyolefin solution together through a coextrusion mold,
The co-extrusion mold is used to form extruded materials.
(i) a mold outlet for extruding the polyolefin solution to form a multi-layer extruded material;
(ii) a first mold part for producing a core layer of extruded material, the first mold part having a flat manifold, the flat manifold for the second polyolefin solution A first mold part having a pressure manifold in communication with a supply side inlet and a mold outlet provided with a slot;
(iii) a second mold part for producing the first surface layer of the extruded material, wherein the second mold part has a cross flow manifold, and the cross flow manifold has one flow path. A part of the first polyolefin solution traverses more than 1 times the width of the second mold part, and the cross-flow manifold is a mold having a supply side inlet and a slot. A second mold part having a pressure manifold in communication with the mold outlet;
(iv) a third mold part for producing the second surface layer of the extruded material, the third mold part having a cross flow manifold, and the cross flow manifold has one flow path. A part of the first polyolefin solution traverses more than 1 times the width of the third mold part, and the cross-flow manifold is a mold having a supply side inlet and a slot. A third mold part having a pressure manifold in communication with the mold outlet;
It has.

    It has been found that the shape memory properties of polyolefins are a factor in maintaining the uniformity of the lateral thickness of the film or sheet exiting the coextrusion mold. 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. When extruding a mixture of polyolefin and diluent, the presence of the diluent reduced the number of polymer chain entanglements, and it was thought that the shape memory effect was not observed. 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 crossflow manifold is adapted to provide a flow path that is long enough to substantially reduce the shape memory characteristics of the thermoplastic material.

  Further, in another embodiment disclosed herein, the mold outlet is a mold outlet provided with a slot having a second mold lip portion as the first mold lip portion, and the first mold lip portion is provided. The part is provided with a flexible lip bar having drive means arranged along the longitudinal direction of the mold outlet.

  Furthermore, in another form disclosed herein, the driving means of the first mold lip portion includes a plurality of individual lip bolts, and changes the width of the mold outlet provided with the slot in the area adjacent to the adjustment member. Be able to.

  Further, in another form disclosed herein, the supply block for the surface layer is configured to divert the polyolefin solution for the surface layer (first polyolefin solution) into the first stream and the second stream. A first stream is supplied to the supply side inlet of the second mold part to produce the first surface layer, and a second stream is fed to the second surface layer to produce the second surface layer. It is supplied to the supply side inlet of the mold part 3.

  These and other advantages, features, and characteristics of the coextrusion mold and manifold system disclosed herein, as well as their effective application and / or use, are discussed in detail below. Will be made clear by reference to the figures attached hereto.

FIG. 1 shows a view of an end face of a coextrusion mold for producing a multilayer film or sheet of thermoplastic resin material. FIG. 2 shows a side view of the first mold part along the 2-2 plane of FIG. 1, for producing a core layer of a multilayer film or sheet of thermoplastic resin material. The coat hanger-like manifold is shown. FIG. 3 is a perspective view of the first portion of the second mold portion along the 3-3 plane of FIG. 1, and shows the surface layer of a film or sheet having a multilayer structure of thermoplastic resin material. 1 shows a crossflow manifold for manufacturing. FIG. 4 is a perspective view of the second portion of the second mold portion along the 3-3 plane of FIG. 1, and shows the surface layer of a film or sheet having a multilayer structure of thermoplastic resin material. 1 shows a crossflow manifold for manufacturing. FIG. 5 shows a side view of a coextrusion mold for producing a multilayer film or sheet of thermoplastic material, showing a flexible lip bar with external drive means. . FIG. 6 shows a schematic view of a co-extrusion mold for producing a film or sheet having a multilayer structure of thermoplastic resin materials, and shows individual thermoplastic resin materials (mixtures of a polymer and a diluent). These flow paths are shown. FIG. 7 shows a drawing of a coat hanger type extrusion mold and shows a flow path of a thermoplastic resin material. FIG. 8 shows a cross-flow type extrusion die, and shows the flow path of the thermoplastic resin material. FIG. 9 shows a cross-sectional view of the two-layer film. FIG. 10 shows a cross-sectional view of a three-layer film. FIG. 11 shows a cross-sectional view of a three-layer film.

  Hereinafter, a description will be given with reference to FIG. 1-11. In these drawings, the same parts are denoted by the same reference numerals.

First, FIG. 1-5 shows a coextrusion mold 10 for producing a multilayer film or sheet of thermoplastic material. The coextrusion die 10 is provided with a die outlet 12 which is a die outlet provided with a slot as shown in the figure, and through this die outlet, a mixture of a polymer and a diluent is a multilayer film. Or it is extruded as a sheet (extruded material). The coextrusion mold 10 is provided with a first mold part 14 for producing a core layer or an intermediate layer.
The first mold part 14 has a flat manifold, which may be in the form of a coat hanger-like manifold 16 as shown, a tail fin-like manifold, or a T-type manifold. There may be. As shown in FIG. 2, the coat hanger-like manifold 16 is provided with a supply side injection port 18 at a distal end portion 20 and further with a pressure manifold 32 communicating with a mold outlet 12 provided with a slot.

  The coextrusion mold 10 further includes a second mold part 24 for producing the first surface layer. As shown in detail in FIGS. 3 and 4, the second mold part includes a crossflow manifold 26 (a). As can be seen from these figures, the cross-flow manifold is provided with a flow path 28, and a portion of the polymer and diluent mixture has a length that is at least one times the transverse length of the second mold part 24. It crosses in the horizontal direction. The cross flow manifold 26 (a) further includes a pressure manifold 32 communicating with the supply side inlet 30 and the mold outlet 12 provided with a slot.

  When a three-layer film or sheet is required, a third mold part 34 for preparing the second surface layer is prepared. The third mold portion 34 is also provided with a cross flow manifold 24. Similar to the second mold part 24, the cross-flow manifold 26 (b) of the third mold part 34 has a flow path 28, and a portion of the polymer and diluent mixture is the third mold. The portion 34 traverses in the lateral direction over a length that is at least one times the lateral width of the portion 34. The cross flow manifold 26 of the third mold part 34 includes a pressure manifold 32 communicating with the supply side inlet 30 and the mold outlet 12 provided with a slot.

  As described later, when a film or sheet of a polyolefin film having a multi-layer structure and a microporous structure is formed from a mixture of a polyolefin and a diluent, a characteristic property relating to shape memory is shown as a characteristic of these materials. 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 shape memory characteristics of a mixture of polyolefin and diluent becomes a problem when ensuring the uniformity of thickness in the width direction of the film or sheet when it comes out of the coextrusion mold as a film or sheet. Manifold design has an impact on this phenomenon, and it has been found that some manifold designs can correct this phenomenon. Therefore, in one embodiment, each of the crossflow manifold 26 of the second mold part 24 and the crossflow manifold of the third mold part 34 substantially eliminates the shape memory characteristics of the extruded material. The flow path has a sufficient length in the width direction. In another embodiment, when a two-layer film or sheet needs to be produced, the crossflow manifold 26 of the second mold section 24 substantially eliminates the shape memory characteristics of the extruded material. The flow path has a sufficient length in the width direction.

  In another embodiment, each of the crossflow manifold 26 of the second mold portion 24 and the crossflow manifold of the third mold portion 34 has at least a portion of the polymer and diluent mixture in the second mold portion 24. The flow path is configured to flow in the width direction at least twice as long as the length in the width direction of the mold portion 24 and the length in the width direction of the third mold portion 34. Furthermore, in another embodiment, where a two-layer film or sheet needs to be produced, the cross-flow manifold 26 of the second mold part 24 is at least part of the polymer and diluent mixture. However, it has a flow path that allows at least twice the length in the width direction of the second mold part 24 to flow in the width direction.

    In particular, as shown in FIGS. 1, 4, and 5, the die outlet 12 provided with the slot of the coextrusion die 10 includes a first die lip portion 36 and a second die lip portion 38. The first mold lip portion 36 includes a flexible lip bar 40 having driving means 42 disposed along the longitudinal direction of the mold outlet. As can be seen from the figure, the external driving means 42 includes a plurality of individual lip bolts 44. Each lip bolt 44 can change the width of the mold outlet 12 provided with a slot in a region adjacent to each adjustment member.

  In particular, referring to FIG. 6, the coextrusion mold 10 includes a surface layer supply block 46 for diverting the flow of material for the surface layer into a first flow S1 and a second flow S2. Can be. The first stream S1 is supplied to the supply-side inlet 30 of the second mold part 24 to produce the first surface layer, and the second stream S2 is used to produce the second surface layer To the supply side inlet 30 of the third mold part 34.

  In another embodiment, a two-layer film or sheet is produced, and the coextrusion mold 10 supplies material to the supply side of the second mold part 24 to produce the first surface layer. A supply block (not shown) for the surface layer that supplies the inlet 30 is provided.

  In particular, in one embodiment shown in FIG. 6, the coextrusion die 10 includes a core layer supply inlet 48 that is in fluid communication with the supply side inlet 18 at the tip portion 20 of the coat hanger-like manifold 16. Is provided.

  The co-extrusion mold and manifold system disclosed herein provides a mixture of polyolefin and diluent, such as a polyolefin solution, in various processes, including the process of forming a “wet” microporous polyolefin film or sheet. It is possible to solve difficult problems that occur when co-extrusion from a mold. Wet processes for producing a multi-layered microporous film are disclosed in, for example, PCT Publication No. WO2008 / 016174, US Patent Publication Nos. US2008 / 0057388, and US2008 / 0057389. All of which are incorporated herein by reference. As shown in FIG. 7, the difficult problem referred to here is that a mold 100 having a coat hanger-like manifold (CH) extrudes a single-layer microporous polyolefin film or sheet 102. For this reason, the thickness of the extruded material becomes non-uniform in the lateral direction of the extruded material due to the shape memory effect generated in 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 in the mold manifold 104 of the mixed solution “S” of polyolefin and diluent. In the mold 100 provided with the coat hanger-like manifold, the main direction of the flow in the manifold is directed toward the mold lip 106, 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. 8, it has been found that this problem can be solved by using a mold 200 with a crossflow manifold (CF). Here, the mixture S crosses over at least twice the width of the mold manifold 204 before the mixture S approaches the mold lip 206. As can be appreciated, this allows most of the mixture S in the mold manifold portion to flow parallel to the mold lip 206. 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.

  The fact that there is no shape memory effect in the width direction in films and sheets made using a mold with a crossflow manifold is the fact that one layer and coat hanger extruded from a mold with a crossflow manifold It is empirically known to be useful in the production of two-layer co-extruded films and sheets comprising a second layer co-extruded from a mold with a cylindrical manifold. However, as can be seen from the cross section of the extruded material 300 shown in FIG. 9, it has been found that this is not the only case. As shown, the intimate planar contact surface between the two layers 302 and 304 is sufficient to counteract the shape memory effect of the layer 302 extruded from a mold with a coat hanger-like manifold. No. As a result, the insight in making a two-layer coextruded film or sheet has led to the idea of using a mold with a crossflow manifold in combination. However, using a mold with three crossflow manifolds to make a three-layer film or sheet coextruded from a mixture of polyolefin and diluent makes the mold very expensive and Has a problem that it becomes complicated and difficult to manufacture.

  Reference is now made to FIG. The co-extrusion mold and manifold system disclosed herein are designed based on the following findings. That is, the three-layer extruded material 400 manufactured using a mold having a cross flow manifold for the surface layer 402 has a large flat interface surface, and thus has a coat hanger-like manifold. It is believed to correct the position of the material of the core layer 404 manufactured using the mold. This counteracts most of the change in thickness in the width direction that occurs in the core layer 404 as a result of the shape memory effect. With the results obtained for the two-layer film 300 shown in FIG. 9, one skilled in the art can use a mold with a crossflow manifold / a mold with a coat hanger-like manifold / a mold with a crossflow manifold. Rather than a coextrusion mold with the above configuration, a mold with a crossflow manifold / a mold with a crossflow manifold / a mold with a crossflow manifold is used. As a result, the results described above were unpredictable.

  As depicted in FIG. 10, even when a mold with a coat hanger-like manifold is used for the core layer 404 and a mold with a cross-flow manifold is used for the surface layer 402 The thickness non-uniformity of the core layer 404 was slightly generated. As can be seen again with reference to FIG. 7, this did not occur as a result of the shape memory effect of the core layer 404, but the apparent appearance of the polyolefin and diluent mixture S under shear deformation in the mold manifold 104. This is caused by an increase in density. As a result, a state where the mixture S of polyolefin and diluent cannot sufficiently approach the end of the mold channel (path) 108 close to the outer edge of the mold 100 is generated. Since the apparent density of the mixture S in the mold channel is high, the amount of mixture S available near the widthwise edge of the mold lip 106 is the viscosity measured by rheological tests. Less than the amount of available mixture S predicted on the basis of. Insufficient core layer material available near the end of the mold lip 106 is considered to be the cause of the non-uniformity of the core layer thickness shown in FIG.

  In order to cope with this problem, in one embodiment, the pressure manifold of the mold 100 having the coat hanger-like manifold for the core layer has an end in the width direction from the cross-sectional area of the central portion of the pressure manifold. The cross-sectional area in the vicinity of the portion 108 is increased. In this way, in order to significantly reduce the degree of thickness variation in the width direction of the core layer of the co-extruded three-layer film or sheet, the polyolefin solution S for the core layer is a mold. A sufficient amount can be made available in the vicinity of the end of the lip portion 106 in the width direction. As shown in FIG. 11, a three-layer coextruded microporous material manufactured using a mold having a coat hanger-like manifold structure modified by increasing the cross section near the end in the width direction of the pressure manifold. The polyolefin film or sheet is a film or sheet having a pair of surface layers 502 and a core layer 504 having a uniform cross section. As described above, this co-extrusion mold is a mold with a cross flow manifold / a mold with a cross flow manifold / a mold with a cross flow manifold. It is not a complicated structure and is not expensive. In addition, this coextrusion die is a mold with a cross flow manifold / a die with a coat hanger-like manifold / a die with a cross flow manifold. A wide range of properties of the diluent mixture can be accommodated. As a result, for polyolefin and diluent mixtures having the property that the viscosity of the mixture measured by the test differs significantly compared to the viscosity of the polyolefin and diluent mixture in the mold during the film manufacturing process. It is possible to dramatically improve the uniformity of the film thickness in the width direction.

  As discussed above, the coextrusion mold and manifold system disclosed herein is useful for forming a multi-layered microporous polyolefin film or sheet. Such a film or sheet is particularly useful when used as a battery separator used under severe conditions. In one form, the multi-layer, microporous polyolefin film 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. .

  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.

The starting materials useful for the production of the aforementioned film or sheet are described below. 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 producing microporous films using the molds disclosed herein, suitable polymers, solvents, and amounts thereof can be found, for example, in PCT International Publication Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389. In one form, the materials of the first and second microporous layers are made from polyethylene. In one form, the material of the first microporous layer is a first polyethylene (PE-1) having a Mw value of about 1 × 10 ⁶ or less or a second polyethylene having a Mw value of at least about 1 × 10 ⁶ . Manufactured from 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 7% by weight with respect to the total amount of PE-1 and UHMWPE-1. % Or less is desirable, and may be at least either a homopolymer or a copolymer. In one form of the above (3) and (4), PP-1 may be at least either a homopolymer or a copolymer, and is about 25% by weight based on the total amount of materials of the first microporous layer. The following content is desirable, more preferably from about 2% to about 15% by weight, and even more preferably from about 3% to about 10% by weight. 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 a coextrusion mold and manifold system of the type shown in FIGS. 1-6. 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 and third layers are made from a first mixture of polyolefin and diluent, e.g., a first polyolefin solution, and the second layer (core layer) is polyolefin and diluent. A second mixture of, for example, 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) mixing (e.g., by melt blending) a first polyolefin composition and at least one first diluent (e.g., a solvent) to prepare a first polyolefin solution;
(2) In order to prepare a second polyolefin solution (the first and second diluents are referred to as `` film forming solvents ''), a second polyolefin composition and at least one second diluent ( For example, a solvent), and
(3) co-extruding first and second polyolefin solutions from a mold of the type disclosed herein to form an extrudate;
(4) Optionally, cooling the extrudate to form a cooled extrudate having a multilayer configuration;
(5) removing at least a portion of the film-forming solvent from the multilayered extruded material or the cooled extruded material to form a multilayered film;
(6) Preferably, the method includes a step of removing at least residual volatile substances from the multi-layered film.
The step (7) of stretching the optional extruded material, the step (8) of treating the optional extruded material with a heating solvent, etc. are performed between steps (4) and (5) if necessary. After step (6), if necessary, a step (9) of stretching an optional multi-layered microporous film, and an optional step (10) of heat-treating the multi-layered microporous film. A step (11) of crosslinking with ionizing radiation as an option, a step (12) of hydrophilic treatment as an option, and the like can be performed. The order of these optional steps is not critical.

  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 blending or melt blending, to create a first polyolefin solution. As an option, for example, as disclosed in WO2008 / 016174, the first polyolefin solution may include one or more antioxidants, additives such as silicate fine powder (pore forming material), and the like. You can also.

  The first and second diluents, for example film-forming solvents, can be solvents that are in a liquid state at room temperature. Suitable diluents are disclosed in 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. The film-forming solvent 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 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 process conditions for mixing the polymer and diluent are disclosed in 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 first polyolefin solution is solvent. The second polyolefin solution can be prepared by the same method used in preparing the first polyolefin solution.

  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.

  The first and second polyolefin solutions are coextruded using a coextrusion mold of the type disclosed herein. Here, the flat surface of the first extruded material layer formed from the first polyolefin solution is in contact with the flat surface of the second extruded material layer formed from the second polyolefin solution. The flat surface of the extruded material can be defined by a first vector that is the machine direction (longitudinal direction) (MD) of the extruded material and a second vector that is the width direction (TD) of the extruded material.

  In another form, the first extruder containing the first polyolefin solution includes a second mold part for producing the first surface layer and a third mold for producing the second surface layer. A second extruder, which is bonded to the mold part and contains the second polyolefin solution, is bonded to the first mold part for producing the core layer. The first and second polyolefin solutions are co-extruded to form a three-layer extruded material with the first and third layers constituting the surface layer or outer layer produced from the first polyolefin solution, Alternatively, they are stacked. The second layer is in planar contact with the two surface layers and constitutes the core layer or intermediate layer of the extruded material disposed between them. Here, the second layer is produced from the second polyolefin solution.

  In general, the gap size of the mold is not particularly critical. For example, a multi-layered sheet molding extrusion mold of the type disclosed herein may 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 gel-like sheet may 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.

  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

  The extruded material having a multilayer structure is formed into a gel sheet having a multilayer structure by cooling, for example. The cooling rate and cooling temperature are not particularly critical. For example, a multi-layered gel sheet may have a cooling rate of at least about 50 ° C./min until the temperature of the multi-layer gel sheet is equal to or lower than the gelation temperature of the multi-layer gel sheet. Cooled by. In one form, the extruded material is cooled to a temperature of 25 ° C. or lower to form a multi-layered gel-like sheet.

  In one form, at least the first and second film-forming solvents are removed from the multilayered extruded material or the cooled extruded material to form a multilayered film. Suitable solvent removal methods are disclosed in WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  In one form, the film obtained by removing the film-forming solvent is dried to remove at least the volatile material left on the film.

  Prior to the step for removing the film-forming solvent, a multi-layered extruded material or a cooled extruded material can be stretched to obtain an extruded material that is at least partially directional.

  Methods for stretching the extruded material are disclosed in Nos. WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  Although not required, the multi-layer or extruded extrusion can be treated with a high temperature solvent. When this treatment is performed, the fibril (formed by stretching a gel-like sheet having a multilayer structure) is given to the relatively thick vein-like structure by performing the high-temperature solvent treatment. A suitable method for this is disclosed in WO2000 / 20493.

  As one form, the multi-layered microporous film can be stretched in at least one axial direction. The selected stretching method is not critical and conventional stretching methods such as the tenter method can be used. During stretching, the film can be heated, but this is not a critical problem. As described herein, when a multilayered gel-like sheet is stretched, stretching a multi-layered microporous polyolefin film in a dry state is referred to as dry stretching, re-stretching, or dry orientation. I'm calling.

  As one form, the microporous film having a multilayer structure can be heat-treated. In one form, the heat treatment includes heat-setting and / or annealing. When carrying out heat-setting, it can be carried out by conventional methods such as the tenter method and / or the roller method.

  Annealing is different from heat-setting in that it heat-treats a multi-layered microporous polyolefin film without applying a load. The choice of annealing method is not a critical issue. Annealing is performed using, for example, a heating furnace provided with a belt conveyor or a heating furnace of a type floated by air. Alternatively, the annealing may be performed after heat-setting with a loose tenter clip. The temperature of the multi-layered microporous polyolefin film during annealing is about the melting point temperature Tm or lower, or about 60 ° C. to [Tm-10 ° C.], or about 60 ° C. to [Tm-5 ° C.]. It is in.

  In one form, a multi-layered microporous polyolefin film can be crosslinked (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 multi-layered microporous olefin film more hydrophilic. [Eg, monomer affinity treatment, surfactant treatment, corona discharge treatment, etc.]) Suitable methods for treatments such as stretching, heat treatment, annealing, hydrophilization are disclosed in WO2008 / 016174, US2008 / 0057388, and US2008 / 0057389.

  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 (20)

A co-extrusion mold for producing a multilayer film or sheet of thermoplastic resin material,
(1) a mold outlet through which a layered extruded material is extruded as a multilayer film or sheet;
(2) A first mold part for producing a core layer, the first mold part having a flat manifold, and the flat manifold having the supply side inlet and the slot. A first mold part with a pressure manifold in communication with the mold outlet;
(3) a second mold part for producing a first surface layer, the second mold part comprising a crossflow manifold, wherein the crossflow manifold is composed of a mixture of polymer and diluent. A part of the cross flow manifold is provided with a flow path that crosses the length of the second mold part in the width direction more than 1 time in the width direction. A second mold part having a pressure manifold communicating with the mold outlet;
(4) a third mold part for producing a second surface layer, the third mold part comprising a crossflow manifold, wherein the crossflow manifold is a mixture of a polymer and diluent. A part of the cross flow manifold is provided with a flow passage that crosses the length of the third mold part in the width direction over one time in the width direction, and the cross flow manifold has a supply side inlet and a slot. A third mold part having a pressure manifold communicating with the mold outlet;
A coextrusion mold characterized by comprising:   2. The coextrusion die according to claim 1, wherein the flat manifold of the first die portion is a coat hanger-like manifold, a tail fin-like manifold, or a T-type manifold. Type.   The coextrusion die according to claim 1 or 2, wherein the flat manifold is a coat hanger-like manifold, and the supply side inlet is disposed at a tip position of the coat hanger-like manifold. Co-extrusion mold.   The coextrusion die according to any one of claims 1 to 3, wherein the pressure manifold of the first die portion has a center portion having a first cross-sectional area and a width having a second cross-sectional area. A coextrusion die comprising a directional end and a second cross-sectional area of the pressure manifold being larger than the first cross-sectional area.   5. The co-extrusion die according to claim 1, wherein the die outlet is a die outlet provided with a slot having a first die lip portion and a second die lip portion. The co-extrusion mold is characterized in that the first mold lip portion includes a flexible lip bar having driving means arranged along the longitudinal direction of the mold outlet.   6. The coextrusion die according to claim 5, wherein the driving means includes a plurality of individual lip bolts, and each of the lip bolts can change a width of a die outlet provided with the slot. Extrusion mold characterized by. 7. A coextrusion die according to any one of claims 1 to 6, wherein the surface layer supply is for diverting the flow of the polymer and diluent mixture for the surface layer into a first flow and a second flow. And further comprising a block, wherein the first stream is fed to the supply side inlet of the second mold part to produce the first surface layer, and the second stream produces the second surface layer. Therefore, the extrusion mold is supplied to the supply side inlet of the third mold part.   8. The coextrusion mold according to claim 1, wherein each of the second mold part cross-flow manifold and the third mold part cross-flow manifold includes a polymer and a diluent. A part of the mixture includes a flow path traversing in the transverse direction over at least twice the width of the second mold part and the width of the third mold part. Extrusion mold characterized by having.   9. The co-extrusion mold according to claim 1, wherein each of the second mold part cross-flow manifold and the third mold part cross-flow manifold includes a polymer and a diluent. A portion of the mixture includes a flow path traversing in the transverse direction over a length of at least 2.5 times the width of the second mold part and the width of the third mold part. Extrusion mold characterized by having. 10. The co-extrusion mold according to claim 1, wherein each of the second mold part cross-flow manifold and the third mold part cross-flow manifold has a shape of an extruded material. An extrusion die comprising a flow path having a length sufficient to substantially reduce memory characteristics. A method for producing a multi-layer extruded material comprising:
(1) mixing at least a first polyolefin and at least a first diluent to prepare a first mixture;
(2) mixing at least a second polyolefin and at least a second diluent to prepare a second mixture;
(3) coextruding the first and second mixtures through a coextrusion mold, and
The coextrusion mold is used to form an extruded material.
(a) a mold outlet through which the extruded material is extruded;
(b) a first mold part for producing a core layer of extruded material, the first mold part having a flat manifold, the flat manifold being a supply for the second mixture A side mold inlet and a first mold part having a pressure manifold in communication with the mold outlet;
(c) a second mold part for producing a first surface layer of extruded material, the second mold part having a crossflow manifold, the crossflow manifold being a first mixture. A part of the cross flow manifold has a flow path that crosses over the width of the second mold part more than 1 times, and the cross flow manifold communicated with a mold outlet having a supply side inlet and a slot. A second mold part having a pressure manifold;
(d) a third mold part for producing a second surface layer of extruded material, wherein the third mold part has a crossflow manifold, and the crossflow manifold is a first mixture. A part of the cross-flow manifold communicates with a mold outlet provided with a supply side inlet and a slot. A second mold part having a pressure manifold;
A method characterized by comprising:   12. The method for producing an extruded material having a multilayer structure according to claim 11, wherein the flat manifold of the first mold portion is a coat hanger-like manifold, a tail fin-like manifold, or a T-type manifold. A method characterized by.   13. A method for producing an extruded material having a multilayer structure according to claim 11 or 12, wherein the flat manifold is a coat hanger-like manifold, and the supply side inlet is disposed at a tip position of the coat hanger-like manifold. The method characterized by being carried out.   A method for producing an extruded material having a multilayer structure according to any one of claims 11 to 13, wherein the pressure manifold of the first mold portion includes a central portion having a first cross-sectional area, and a first portion. A method comprising: a widthwise end having a cross-sectional area of 2, wherein the second cross-sectional area of the pressure manifold is greater than the first cross-sectional area.   15. The method for producing an extruded material having a multilayer structure according to claim 11, wherein a mold outlet of the coextrusion mold includes a first mold lip part and a second mold lip part. A mold outlet provided with a slot, wherein the first mold lip portion comprises a flexible lip bar having drive means arranged along the longitudinal direction of the mold outlet. Feature method.   The method for producing an extruded material having a multilayer structure according to claim 15, wherein the driving means of the mold outlet provided with the slot of the coextrusion mold comprises a plurality of individual lip bolts, Each of the lip bolts can change the width of the mold outlet provided with the slot. 17. A method for producing a multi-layer extruded material according to claim 11, wherein the co-extrusion mold is configured to change the flow of the first mixture into a first flow and a second flow. The first flow is supplied to the supply side inlet of the second mold part to produce the first surface layer, and the second flow is further provided. Is supplied to the supply side inlet of the third mold part to produce the second surface layer.   A method for producing an extruded material having a multilayer structure according to any one of claims 11 to 17, wherein a crossflow manifold of the second mold part and a crossflow manifold of the third mold part are provided. Each includes a portion of the polymer and diluent mixture transversely over a length at least twice the width of the second mold part and the width of the third mold part. A method characterized in that each channel is provided with a transverse channel.   A method for producing an extruded material having a multilayer structure according to any one of claims 11 to 18, comprising: a cross flow manifold of the second mold part; and a cross flow manifold of the third mold part. Each part of the first mixture traverses laterally over a length at least 2.5 times the width of the second mold part and the width of the third mold part. A method characterized by comprising a flow path. 20. The coextrusion die according to claim 11, wherein each of the crossflow manifold of the second mold part and the crossflow manifold of the third mold part has a shape of an extruded material. An extrusion die comprising a flow path having a length sufficient to substantially reduce memory characteristics.

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