JP2024021193A - Film for isostatic pressing, bag for isostatic pressing, and method for isostatic pressing - Google Patents

Abstract

An object of the present invention is to provide a film for isostatic pressing, a bag for isostatic pressing, and a method for isostatic pressing, which have excellent puncture strength and have a low burden on the environment. A film for isostatic pressing of the present invention is a laminated film having a high-density polyethylene layer. The high-density polyethylene layer (A) is a uniaxially stretched film, and the high-density polyethylene layer (B) is a uniaxially stretched film, and the high-density polyethylene layer (A) is It is preferable that the layers are laminated in a direction different from the stretching direction. [Selection diagram] Figure 1

Description

The present invention relates to a film for isostatic pressing, a bag for isostatic pressing, and a method of isostatic pressing used in the production of laminated ceramic electronic components.

In recent years, multilayer ceramic electronic components have attracted attention. This is because ceramic electronic components constructed by laminating ceramics can be made smaller and larger in capacity, and as a result, needs are expanding in various fields such as electricity, automobiles, and communications.

For example, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2011-77391) discloses a method for manufacturing a multilayer ceramic capacitor, which uses only one adhesive tape as a process material throughout the lamination process, thermocompression bonding process, and dicing process, which significantly improves the manufacturing process. A method of manufacturing a multilayer ceramic capacitor that reduces cost and improves yield has been proposed.

The method for manufacturing a multilayer ceramic capacitor described in Patent Document 1 includes a lamination step in which ceramic green sheets are laminated in tens to hundreds of layers, and a ceramic green sheet lamination process in which the laminated ceramic green sheets are pressed and heated to compact them. A manufacturing method for a multilayer ceramic capacitor, which includes a thermocompression bonding process for forming a ceramic green sheet laminate and a dicing process for dicing the obtained ceramic green sheet laminate. Only this material is used as a process material.

Patent Document 2 (Japanese Unexamined Patent Publication No. 2010-110896) discloses a packaging material for hydrostatic press that has pinhole resistance that can withstand hydrostatic press even if it is thin, and a method of hydrostatic press using the packaging material. is proposed.

The isostatic press method described in Patent Document 2 uses a film in which a biaxially stretched linear low-density polyethylene layer is laminated onto a film having a nylon layer and/or a polyethylene terephthalate layer as a packaging material for the isostatic press. The film is formed into a bag with the biaxially stretched linear low-density polyethylene layer on the inside, and the item to be pressure-molded is placed in the bag, sealed, and hydrostatically pressed.

Furthermore, Patent Document 3 (Japanese Unexamined Patent Application Publication No. 2014-88181) proposes an inexpensive packaging bag that has low material costs, does not require special equipment, does not take many days to process, and has improved productivity. .

The packaging bag described in Patent Document 3 is a packaging bag used in a hydrostatic press for forming a laminated ceramic block, and includes a biaxially oriented polypropylene film serving as a base material layer and a linear low-density polyethylene film serving as a sealant layer. This uses packaging materials laminated with polyethylene resin interposed therebetween using a sandwich lamination method.

Japanese Patent Application Publication No. 2011-77391 Japanese Patent Application Publication No. 2010-110896 Japanese Patent Application Publication No. 2014-88181

The general method used to manufacture multilayer ceramic electronic components is to laminate ceramic green sheets on which a large number of internal electrodes are formed, press-form a block of this laminate, then cut it into a predetermined size and fire it. .
In this case, the method for forming the laminate is to vacuum pack the stacked ceramic green sheets in a packaging bag, and then press the stacked ceramic green sheets in all directions using isostatic isostatic press. A molding method is performed in which pressure treatment is performed.
The packaging bag used in this isostatic pressing process is required to protect precision ceramic electronic components while being subjected to hydrostatic pressure of approximately 30 to 400 MPa. However, since the ceramic green sheet laminate has corners and irregularities, pinholes may occur during pressing in packaging bags using conventional films. When pinholes are formed in the film, water enters through the pinholes, wets the ceramic green sheet laminate, and results in defective products, resulting in a decrease in yield.

In the method for manufacturing laminated ceramic electronic components described in Patent Document 1, a ceramic green sheet is placed in a polyethylene bag, vacuum packed, and subjected to a hydrostatic pressure machine, but in this case, pinholes may occur and the strength is insufficient. Ta.
In addition, in the packaging material for hydrostatic press described in Patent Document 2, a film having a nylon layer and a polyethylene terephthalate layer is laminated with a biaxially stretched linear low-density polyethylene layer and is subjected to isostatic press. However, in this case, it is necessary to prepare a film with a complicated layer structure, which is not preferable from the viewpoint of cost and environment.
Furthermore, the packaging material described in Cited Document 3 has a polyethylene resin layer made of a low density polyethylene resin provided on a base material layer of a biaxially stretched polypropylene film, and a sealant layer made of a linear low density polyethylene film is laminated thereon. In this case as well, there was a problem that the strength was insufficient, and if release PET, aluminum plates, etc. were packaged together with the laminate, the corners would strongly hit the film and pinholes would easily occur.

In addition, as the need for multilayer ceramic electronic components has expanded in various fields in recent years and production volumes have increased significantly, packaging bags are being discarded every time the harsh isostatic pressing process is performed. Therefore, there is a problem of industrial waste, which is also undesirable from an environmental point of view.
Additionally, the use of petroleum products is said to be a major cause of global warming, and it is hoped that by using reusable materials in the production process of semiconductor parts, we will be able to reduce our dependence on fossil resources. There is.
Among recyclable general-purpose plastics, polyethylene resin is one of the resins with the highest annual production volume, and the use of polyethylene resin, which can be reused for various purposes such as films, bags, containers, and molded products, is attracting attention.
However, since there are restrictions on the quality of reusable materials, it has been difficult to develop environmentally friendly isostatic pressing films, which require strict performance in high-temperature, high-pressure environments.

The present invention has been made to solve the above problems, and the purpose of the present invention is to:
An object of the present invention is to provide a film for isostatic pressing, a bag for isostatic pressing, and a method for isostatic pressing, which have excellent puncture strength and have a small burden on the environment.
Another object of the present invention is to provide a film for isostatic pressing, a bag for isostatic pressing, and a method for isostatic pressing, which are made of a single material and are easy to separate and reuse. It is in.

(1)
A film for isostatic pressing according to one aspect consists of a laminated film having a high-density polyethylene layer (A).

High-density polyethylene is a crystalline polyethylene in which repeating units of ethylene are bonded in a linear chain, and it has excellent rigidity and abrasion resistance, so it can be used as a film for isostatic pressing with excellent puncture strength. .
Moreover, since high-density polyethylene is used in various fields including packaging materials, it can be used as a film for isostatic pressing that is easy to reuse and has a low environmental impact.

(2)
The film for isostatic pressing according to the second invention is a film for isostatic pressing according to one aspect, and the high-density polyethylene layer (A) may be a uniaxially stretched film.

Thereby, it is possible to obtain a film for isostatic pressing that has excellent puncture strength even if it is thin. Because it has excellent puncture strength, pinholes are less likely to occur during isostatic pressing, reducing the number of defective products such as laminated ceramic electronic components.
In addition, since it has heat shrinkability, by heating it with hot water or the like during isostatic pressing, it can be made into a film for isostatic pressing that has excellent conformability to a green sheet laminate.

(3)
The film for isostatic pressing according to the third invention is the film for isostatic pressing according to the second invention, wherein the laminated film further includes a high-density polyethylene layer (B), The polyethylene layer (B) may be a uniaxially stretched film, and the stretching direction of the high-density polyethylene layer (A) and the stretching direction of the high-density polyethylene layer (B) may be stacked in different directions.

By laminating layers with different orientation directions due to stretching, a laminated film is obtained in which layers of fiber crystals with different orientations are laminated. Therefore, since the layer with high mechanical strength such as tensile strength and breaking strength is structured in a network, it is difficult to tear even when a puncture force is applied, and it is a film for isostatic pressing that has excellent puncture strength even if it is thin. can do.
Furthermore, since strength can be ensured even if the film is made thinner, it is possible to reduce the amount of petroleum products used in isostatic pressing, thereby reducing the burden on the environment.
Note that the term "laminated in different stretching directions" is not limited to the case where an MD stretched film and a TD stretched film are laminated as shown in the examples. For example, two MD stretched films are laminated in the direction of the stretching axis. This also includes the case where the layers are stacked so that they are different.

(4)
The isostatic pressing film according to the fourth invention is the isostatic pressing film according to the third invention, wherein the laminated film further has a laminate layer, and the laminate layer contains polyethylene. It is an extruded resin layer, and may be laminated between a high-density polyethylene layer (A) and a high-density polyethylene layer (B).

Thereby, the high-density polyethylene layer (A) and the high-density polyethylene layer (B) can be extrusion laminated with polyethylene.
Since no adhesive is used, there is no problem with residual solvent. Furthermore, since no solvent volatilization occurs during film production, it is preferable in terms of environmental impact. Furthermore, the time required for curing the adhesive becomes unnecessary, and the power required for the aging process can be reduced.

Further, in this case, as the polyethylene used in the extrusion laminate, a material of a used film for isostatic pressing can be used for part or all of the extrusion layer or a layer such as the sealant layer. By doing this, it becomes possible to reuse the film used in isostatic pressing and create a film for isostatic pressing again, thereby creating an environmentally friendly, circular manufacturing process. It can be realized.

(5)
The isostatic pressing film according to the fifth invention is the isostatic pressing film according to the third invention, wherein the laminated film further has a laminate layer, and the laminate layer is made of an adhesive resin. It is a membrane and may be laminated between a high-density polyethylene layer (A) and a high-density polyethylene layer (B).

This makes it possible to reduce the thickness of the laminate layer while ensuring high laminate strength. Therefore, it is possible to obtain a high-performance film for isostatic pressing while reducing the thickness of the film.
Note that a polyurethane adhesive may be used for the adhesive resin film in this case.

(6)
A film for isostatic pressing according to a sixth invention is a film for isostatic pressing according to any one of the fifth invention from one aspect, wherein the laminated film further has a sealing layer, and the laminated film further includes a sealing layer. The layer is a resin layer made of polyethylene, and may be laminated on the outermost layer of the laminated film.

Thereby, the green sheet laminate can be protected by thermal fusion, and isostatic pressing can be easily performed.

(7)
A film for isostatic pressing according to a seventh invention is a film for isostatic pressing according to any one of the sixth inventions from one aspect, wherein the laminated film has a polyethylene resin content of 90%. It may be more than % by weight.

Conventionally, it has been difficult to make films for isostatic pressing, which require severe performance in high-temperature, high-pressure environments, as monomaterials because making them monomaterials imposes restrictions on the material of the film. However, since it is a monomaterial film for isostatic pressing containing 90% by weight or more of polyethylene resin, it can be easily separated and reused.
Furthermore, polyethylene is environmentally friendly because it can be reused for various purposes such as films, bags, containers, and molded products.

(8)
A film for isostatic pressing according to an eighth aspect of the invention is a film for isostatic pressing according to any one of the seventh aspects of the invention, wherein the laminated film is used for isostatic pressing. The film may also contain a polyethylene resin.

As a result, the used film can be reused as a raw material after performing isostatic pressing, so that an environmentally friendly circulating isostatic pressing process can be achieved.
In addition, the environmental load associated with manufacturing the multilayer ceramic electronic component can be reduced.

(9)
A bag for isostatic pressing according to another aspect is made using the film for isostatic pressing according to any one of the first to eighth aspects of the invention.

Thereby, the green sheet laminate can be easily packaged and subjected to isostatic pressure molding.

(10)
An isostatic pressing method according to another aspect of the present invention includes a method for isostatic pressing according to one aspect of the invention, using the isostatic pressing film according to any one of the eighth aspects of the invention or the isostatic pressing bag according to the ninth invention. This is to pressurize the package.

As a result, it is possible to use an isostatic pressing method that is environmentally friendly, and it is possible to obtain a laminated ceramic electronic component with less load on the environment.

It is a figure showing an example of the bag for isostatic pressure molding of this embodiment. 1 is a schematic cross-sectional view for explaining the structure of a film for isostatic pressing of Example 1. FIG. FIG. 2 is a schematic cross-sectional view for explaining the structure of a film for isostatic pressing of Example 2. FIG. 3 is a schematic cross-sectional view for explaining the structure of a film for isostatic pressing of Example 3.

(Isostatic isostatic pressing)
Multilayer ceramic electronic components such as multilayer capacitors, multilayer inductors, multilayer alumina substrates, multilayer varistors, and multilayer piezoelectric elements are usually manufactured by isostatically forming ceramic raw materials.
For example, in the case of a multilayer ceramic capacitor (MLCC), ceramic green sheets are laminated in tens to hundreds of layers (lamination process), and the laminated ceramic green sheets are pressed and compacted to form a laminate molded product (pressure is applied). It is usually manufactured by dicing the obtained laminate molded product (press molding step) (dicing step) and firing it (firing step).
In this pressure forming process, isostatic isostatic pressing is generally employed, which allows the layers of ceramic green sheets to be bonded together by a synergistic effect of heat and high pressure. Pressure treatment using hot water with uniform pressure from all directions suppresses variations in density within the laminate and provides excellent dimensional accuracy, improving the performance of the final product after firing. Depending on the purpose of processing, cold isostatic pressing (CIP), which performs isostatic pressing using water close to room temperature, or hot water isostatic pressing (CIP), which performs isostatic pressing using heated hot water, etc. WIP) is employed as appropriate, but the film for isostatic pressing of the present invention may be used in any method.

FIG. 1 is a diagram showing an example of a bag 10 for isostatic pressing according to the present embodiment.
In isostatic pressing, the ceramic green sheet laminate 20 is placed in a dedicated molding bag 10. At this time, the ceramic green sheet laminate 20 can be placed in the molding bag 10 while being protected by a release-processed PET film 30 or the like and placed on a substrate 40 made of aluminum or the like. Then, the bag is vacuum packed for degassing, the mouth of the bag is closed by heat sealing or the like, and the bag is placed into an isostatic press molding machine.
In isostatic isostatic press molding, a pressure of about 30 to 400 MPa is usually applied, but the ceramic green sheet laminate 20 has corners and irregularities, and may have embedded electrodes, so the molding bag There is a problem in that pinholes are likely to occur in 10. Furthermore, since a strong force is applied to the ends of the PET film 30 or the ends of the substrate 40, there is also the problem of pinholes.

In addition, as a packaging method for the laminate 20, in addition to the method of enclosing the laminate 20 in a molded bag 10 prepared in advance as described above, it is also possible to continuously pack the laminate 20 by using a film for isostatic pressure forming wound into a roll. A method of packaging has also been devised.
For example, a film for isostatic pressing is unwound from a roll, a concave shape is formed in the film using a heated vacuum mold, etc., the laminate 20 is placed in the concave part, and a lid is covered with a film-like top material. This is a method for continuous packaging.
In this case as well, films for isostatic pressing have the problem of pinholes.

(Laminated film)
The laminated film of this embodiment has at least a layer of high density polyethylene. A high-density polyethylene film has excellent puncture strength and excellent reusability.
This high density polyethylene layer A is a uniaxially stretched high density polyethylene film. Moreover, the laminated film of this embodiment further has a high-density polyethylene layer B, and this high-density polyethylene layer B is also a uniaxially stretched high-density polyethylene film system.
The uniaxially stretched high-density polyethylene layer A and high-density polyethylene layer B are laminated so that their stretching directions are different from each other. In this case, the angle formed by the stretching direction of high-density polyethylene layer A and the stretching direction of high-density polyethylene layer B is preferably 25° or more, more preferably 45° or more, even more preferably 60° or more, and most preferably 90°. .
As a result, high-density polyethylene films with fiber crystals in different directions are laminated, resulting in a laminated film with a mesh-like structure of layers with high mechanical strength, which is suitable for isostatic pressing with excellent puncture strength even though it is thin. It can be a film.

(High density polyethylene layers A, B)
The high-density polyethylene layer A of this embodiment is preferably a longitudinally stretched (MD stretched) film. In this case, the lower limit of the stretching ratio is preferably 2 times or more, more preferably 3 times or more, and even more preferably 4 times or more. This makes it possible to ensure sufficient strength. Further, the upper limit of the stretching ratio is preferably 8 times or less, more preferably 7 times or less. This makes it less susceptible to shrinkage even when heated and hydrostatically pressed.
Further, the lower limit of the thickness of the high-density polyethylene layer A of this embodiment is preferably 20 μm or more, more preferably 30 μm or more, and even more preferably 40 μm or more. Further, the upper limit of the thickness is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less. This makes it possible to ensure sufficient strength and is superior in terms of environment and cost.

As an example of a method for manufacturing this high-density polyethylene layer A, for example, high-density polyethylene having a density of 0.955 g/cm ³ or more and 0.965 g/cm ³ or less is extruded from a T-die at an extrusion temperature of 240°C, and then extruded at 95°C. A longitudinal uniaxial film can be obtained by forming an unstretched original film into a film using a cooling roll, and then stretching the film in the longitudinal direction by 2 times or more and 8 times or less by pressing with pinch rolls at 120°C.
The raw material polyethylene preferably has a density of 0.94 g/cm ³ or more, and preferably has a MI ₁₀ /MI _2.16 value of 10 or less. Further, the raw material polyethylene may be a resin composition appropriately mixed with other resins such as low density polyethylene within the above range, or a copolymer with an α-olefin other than ethylene may be used as appropriate.

The high-density polyethylene layer B of this embodiment is preferably a transversely stretched (TD stretched) film. In this case, the lower limit of the stretching ratio is preferably 3 times or more, more preferably 5 times or more, and even more preferably 8 times or more. This makes it possible to ensure sufficient strength. Further, the upper limit of the stretching ratio is preferably 20 times or less, more preferably 13 times or less. This makes it less susceptible to shrinkage even when heated and hydrostatically pressed.
Further, the thickness of the high-density polyethylene layer B of this embodiment is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 30 μm or less, and even more preferably 15 μm or more and 22 μm or less. This makes it possible to ensure sufficient strength and is superior in terms of environment and cost.
Further, in the laminated film of this embodiment, it is more preferable to provide two or more high-density polyethylene layers B, most preferably two layers. This makes it possible to ensure sufficient strength. In addition, when providing two or more high-density polyethylene layers B, it is preferable that the directions of the stretching axes of the high-density polyethylene layers B are aligned in the same direction.
As a result, layers of fiber crystals having different directions are laminated in a mesh pattern, so that a film for isostatic pressing having excellent puncture strength even though it is thin can be obtained. In addition, the design of the uniaxially stretched film in this case can be changed within the range that achieves the above functions and effects, and includes, for example, a case where one stretching ratio of the biaxially stretched film is significantly larger than the other stretching ratio. . A specific example of such a stretching ratio is, for example, a case where one stretching amount is 4 times or more different from the other stretching amount.

As an example of a method for producing this high-density polyethylene layer B, for example, 100 parts by weight of high-density polyethylene with a density of 0.95 g/cm ³ or more and 0.97 g/cm ³ or less and 100 parts by weight of high-density polyethylene with a density of 0.913 g/cm 3 or more and 0.97 g/cm ³ or less are used. A raw material polyethylene is prepared by mixing 20 parts by weight or more and 40 parts by weight or less of low-density polyethylene having a density of 928 g/cm ³ or less, discharged from a film die to form an unstretched original film, and heated at 100°C or more to 140°C. A horizontally uniaxially stretched film can be obtained by stretching the film by 10 times or more and 20 times or less in the following tenter.
This raw material polyethylene does not need to be mixed with low-density polyethylene, but by mixing low-density polyethylene, transparency can be improved and a film that is difficult to tear can be made. Further, as the raw material polyethylene, a copolymer with an α-olefin other than ethylene may be appropriately used.

Furthermore, in the laminated film of this embodiment, a case is illustrated in which one high-density polyethylene layer A and two high-density polyethylene layers B having different thicknesses are laminated, but the structure is not limited to this. do not have.
That is, the high-density polyethylene layer B having the same thickness as the high-density polyethylene layer A may be used to laminate each film with different stretching axes. In this case, the preferred thickness of the high density polyethylene layer B is the same as the preferred thickness of the high density polyethylene layer A.
Furthermore, the order of lamination is not particularly limited, and in this embodiment, high-density polyethylene layer A, high-density polyethylene layer B, and sealing layer are laminated in this order, but high-density polyethylene layer A and high-density polyethylene layer B The order of can be reversed. Further, when two or more high-density polyethylene layers B are used, the high-density polyethylene layer B may be laminated with the high-density polyethylene layer A sandwiched therebetween.
In this specification, for convenience, a layer formed of a longitudinally stretched film will be referred to as A, and a layer formed of a horizontally stretched film will be referred to as B; however, a layer formed of a longitudinally stretched film will be referred to as B, and a longitudinally stretched film The layer formed in step A may be used as layer A.
Further, in addition to the above, layers having other functions such as a barrier layer and a mold release treatment layer can be provided as appropriate. These layers are preferably composed of polyethylene resin, but the design may be changed as appropriate within the scope of the purpose and effect of the present invention.

(Laminate layers 11, 12)
In the laminated film of this embodiment, high-density polyethylene layers A and B are laminated with laminate layers 11 and 12 interposed therebetween. Also, in the case where there are two or more high-density polyethylene layers B, they are laminated with the laminate layers 11 and 12 interposed therebetween.
As this lamination method, a method of providing an extruded resin layer 11 by an extrusion lamination method, and a method of applying an adhesive and bonding with an adhesive resin film 12 can be adopted as appropriate.

As a method for extrusion lamination using the extruded resin layer 11, for example, raw polyethylene is extruded from an extruder while being melted at about 320° C., and the high-density polyethylene layer A, the molten extruded resin layer 11, and the high-density polyethylene layer B are combined. By laminating them together, a laminated film can be obtained.
As the raw material polyethylene in this case, low density polyethylene, high density polyethylene, or a mixture with other olefins can be used as appropriate. In particular, by mixing the material of the used isostatic pressing film with the raw material polyethylene, it is possible to realize a circular manufacturing process that is excellent for the environment.
During extrusion lamination, each film may be subjected to a surface treatment to improve adhesion. Specifically, corona treatment, plasma treatment, anchor coat treatment, primer coat treatment, etc. may be performed. Note that from the viewpoint of a monomaterial, it is preferable to use an adhesive-less extruded resin layer 11 that is not subjected to anchor coating treatment or primer coating treatment.
Further, the thickness of the extruded resin layer 11 is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less. This allows the film to have sufficient adhesiveness and hardness.

As a method for dry laminating with the adhesive resin film 12, for example, a polyurethane adhesive is appropriately applied to the high-density polyethylene layer A using a roller or the like, and then dried using a high-temperature dryer. Then, a laminated film can be obtained by bonding the high-density polyethylene layer A and the high-density polyethylene layer B, on which the adhesive resin film 12 is formed, to each other.
In this case, the laminating adhesives include polyvinyl acetate adhesive, polyacrylic acid ester adhesive, cyanoacrylate adhesive, ethylene copolymer adhesive, cellulose adhesive, polyester adhesive, and polyamide adhesive. A polyimide adhesive, an amino resin adhesive, a phenol resin adhesive, an epoxy adhesive, a polyurethane adhesive, a (meth)acrylic acid adhesive, or a silicone adhesive can be used. Among these, polyurethane adhesives can be preferably used in terms of adhesiveness to polyethylene and flexibility of the adhesive resin film 12. Further, the polyurethane adhesive may be in any form such as aqueous type, solution type, emulsion type, or dispersion type, but it is preferable to use a solvent type in terms of productivity and cost.
Further, the thickness of the extruded resin layer 11 is preferably 5 μm or more and 50 μm or less, more preferably 10 μm or more and 40 μm or less. This allows the film to have sufficient adhesiveness and hardness.

Further, as another method of dry laminating using the adhesive resin film 12, it is also possible to use a solvent-free dry laminating method using an adhesive or the like that does not use an organic solvent. This eliminates the need for a drying process and eliminates the release of solvent, making it possible to provide a laminated film that is environmentally friendly. As the adhesive in this case, for example, an aqueous type, a hot melt type, a film type, or a reactive type can be suitably used.
Further, as yet another method for laminating the laminate layers 11 and 12, it is also possible to use a thermal lamination method in which a laminating film is used for thermal fusion. As the laminating film in this case, a film of low density polyethylene or linear low density polyethylene can be suitably used. As a result, it can be made into a monomaterial and there is no release of solvent, making it possible to create a laminated film that is environmentally friendly.

(Seal layers 14, 15, 16)
The laminated film of this embodiment has a heat-sealable sealing layer as the outermost layer. This allows the ceramic green sheet laminate 20 to be efficiently and reliably packaged, and also maintains water stoppage even during isostatic pressing under high temperature and high pressure, thereby preventing the laminate 20 from getting wet and becoming defective. be able to.
The sealing layer of this embodiment is a resin layer made of polyethylene, and may be an extruded sealing layer 15 extruded with an extruder, or a film sealing layer 16 using a separately prepared raw film. good. Furthermore, when forming the extrusion seal layer 15 or the film seal layer 16, the AC seal layer 14 may be provided by applying an anchor coating agent or an adhesive, if necessary.

In the case of the extruded seal layer 15, it is preferable to use low density polyethylene or linear low density polyethylene as the raw material polyethylene. Thereby, it is possible to obtain a laminated film that has excellent moisture resistance and heat sealability. Moreover, the extrusion sealing layer 15 can be directly extrusion laminated and attached to the high-density polyethylene layers A and B. Further, two or more extruded sealing layers 15 may be provided, and in that case, a layer of resin other than polyethylene may also be provided.
In the case of the film seal layer 16, it is preferable to use linear low density polyethylene as the raw film. Thereby, it is possible to obtain a laminated film that has excellent moisture resistance and heat sealability. The film seal layer 16 and the high-density polyethylene layers A and B are laminated by laminate layers 11 and 12.
Although the melting points of the seal layers 14, 15, 16 are not particularly limited, it is preferable that the outermost seal layers 15, 16 have a melting point lower than that of the extruded resin layer 11. This can prevent the inner layer from seeping out during bag making.

(mono material)
The film for isostatic pressing of this embodiment is a monomaterial film made of polyethylene resin. Until now, due to restrictions on film materials, it has been difficult to create monomaterials for isostatic isostatic pressing films, which require strict performance and stable properties in high-temperature, high-pressure environments.
The laminated film of the isostatically pressed film of this embodiment includes a layer of high-density polyethylene, so it has excellent mechanical strength. Furthermore, the uniaxially stretched high-density polyethylene layer A and the uniaxially stretched high-density polyethylene layer B are stacked in different stretching directions, so that pinhole resistance is particularly excellent.
Since the film for isostatic pressing of the present embodiment is a monomaterial film, it is possible to easily separate and reuse film waste generated during the manufacturing process of laminated ceramic electronic components. In addition, polyethylene is one of the general-purpose plastics with the highest annual production volume, and is used in a variety of applications such as films, bags, containers, and molded products, so it can be reused as a raw material in a wide range of ways.
In this case, as a monomaterial film for isostatic pressing, the content of polyethylene resin in the laminated film is preferably 90% by weight or more, more preferably 95% by weight or more, and 98% by weight. It is more preferable that it is above. The higher the purity, the higher the performance of the polyethylene resin, which expands the range of products that can be reused as raw materials.

Furthermore, by reusing the polyethylene resin separated in this embodiment for the extruded resin layer 11 or a part of the seal layers 15 and 16, an environmentally friendly recycling molding process can be achieved. In addition, the environmental load associated with manufacturing the multilayer ceramic electronic component can be reduced. As a method of reusing a part of the layers such as the extrusion layer 11 or the sealing layers 15 and 16, there is, for example, a method of mixing it into material pellets and cyclically reusing it as a polyethylene resin.

(Example 1)
As the high-density polyethylene layer A, one original film of longitudinally uniaxially stretched polyethylene film was prepared. Further, as the high-density polyethylene layer B, two original sheets of polyethylene film that had been uniaxially stretched laterally were prepared. Then, by an extrusion lamination method using low-density polyethylene, "high-density polyethylene layer A/extruded resin layer 11/high-density polyethylene layer B/extruded resin layer 11/high-density polyethylene layer B" is laminated in this order to form a laminated film. I got it.
For extrusion lamination, the surfaces of high-density polyethylene layers A and B were subjected to corona discharge, and low-density polyethylene was processed using an extrusion laminator equipped with a 110 mmφ extruder under the conditions of a die temperature of 320°C, an air gap of 150 mm, and a processing speed of 130 m/min. I extruded it and laminated it. Note that no adhesive such as anchor coat was used in extrusion lamination.

The laminated film obtained as described above was further laminated with low density polyethylene by extrusion lamination to form a sealing layer 15 to obtain a film for isostatic pressing (total thickness: 146 μm).
The extrusion lamination conditions for forming the seal layer 15 are the same as those for the extruded resin layer 11.

Details of the raw materials used for producing each layer are as follows.
・High-density polyethylene layer A: manufactured by Tokyo Ink Co., Ltd., PE3K-BT, density 0.950 g/cm ³ , thickness 50 μm, longitudinally uniaxially stretched high-density polyethylene film ・High-density polyethylene layer B: manufactured by Denka Co., Ltd., Calariyan , density 0.945 g/cm ³ , thickness 18 μm, horizontally uniaxially stretched high-density polyethylene film/extruded resin: manufactured by Tosoh Corporation, Petrocene 203, low-density polyethylene, density 0.919 g/cm ³ , MFR (190°C 2160 g) 8g/10 minutes, low density polyethylene: manufactured by Tosoh Corporation, Petrocene 212, density 0.919g/ ^cm3 , MFR (190℃ 2160g) 13g/10 minutes

The structure of the film for isostatic pressing obtained in this way is as shown in FIG. )/extruded resin layer 11 (15 μm)/high density polyethylene layer B (18 μm)/seal layer 15 (30 μm)”.
The film for isostatic pressure molding of Example 1 does not use any adhesive, so it is a completely monomaterial film composed only of polyethylene resin.

(Example 2)
Instead of extrusion lamination in Example 1, dry lamination was performed.
For dry lamination, the adhesive for dry lamination was applied with a roll while unrolling the film of the high-density polyethylene layer A, and the adhesive resin film 12 was formed by heating and drying at 80° C. for 5 seconds using a dryer. . Next, it was pressure-bonded with the film of high-density polyethylene layer A, wound up into a roll, and aged.

The laminated film obtained as described above is further coated with an anchor coating agent, and then laminated with low density polyethylene by extrusion lamination to form the sealing layer 14 and the sealing layer 15, and then isostatically formed. A film (total thickness: 121 μm) was obtained.

Details of the raw materials used for producing each layer are as follows.
・Adhesive: 2-component curable urethane adhesive, manufactured by Mitsui Chemicals, main agent A616, curing agent 65
・Anchor coating agent: 2-component curable urethane adhesive, manufactured by Mitsui Chemicals, main agent A3210, curing agent A3072

As shown in FIG. 3, the structure of the film for isostatic pressing obtained in this manner is as follows: "High-density polyethylene layer A (50 μm)/Adhesive resin film 12 (2 μm)/High-density polyethylene layer B ( 18 μm)/Adhesive resin film 12 (2 μm)/High density polyethylene layer B (18 μm)/Seal layer 14 (1 μm)/Seal layer 15 (30 μm)”.
The film for isostatic pressing of Example 2 uses an adhesive between layers, but is a monomaterial film containing 96% by weight of polyethylene resin, and has excellent recyclability.

(Example 3)
The thickness of the sealing layer 15 of Example 2 was set to 20 μm, and a linear low-density polyethylene film was further laminated as the sealing layer 16 by extrusion lamination.
Details of the raw materials used for producing the seal layer 16 are as follows.
・Linear low-density polyethylene film: manufactured by Sky Film Co., Ltd., HR543, density 0.918 g/cm ³ , MFR (190°C 2160 g) 3.8 g/10 minutes, unstretched LLDPE film

As shown in FIG. 4, the structure of the film for isostatic pressing obtained in this manner is as follows: "High-density polyethylene layer A (50 μm)/Adhesive resin film 12 (2 μm)/High-density polyethylene layer B ( 18 μm)/Adhesive resin film 12 (2 μm)/High density polyethylene layer B (18 μm)/Seal layer 14 (1 μm)/Seal layer 15 (20 μm)/Seal layer 16 (30 μm)”.
The film for isostatic pressing of Example 3 uses an adhesive between layers, but is a monomaterial film containing 96% by weight of polyethylene resin, and has excellent recyclability.

(Example 4)
A laminated film was obtained in the same manner as in Example 1, except that the extruded resin layer 11 and the high-density polyethylene layer B were not provided in the laminated film (excluding the sealing layer) of Example 1.

(Example 5)
In the laminated film of Example 1 (excluding the sealing layer), high-density polyethylene layer B was replaced with high-density polyethylene layer A, and two longitudinally uniaxially stretched polyethylene films (50 μm) were laminated by extrusion lamination so that they were in the same axial direction. did.
Then, a laminated film was obtained in the same manner as in Example 1, except that the extruded resin layer 11 and the high-density polyethylene layer B were not provided.

(Comparative example 1)
An unstretched low-density polyethylene film (100 μm) was prepared and evaluated in the same manner as in Example 1. Details of the film are as follows.
・Unstretched low-density polyethylene film: Z481, LDPE film with a thickness of 100 μm, manufactured by Ube Maruzen Polyethylene Co., Ltd.

(Comparative example 2)
A uniaxially stretched low density polyethylene film (50 μm) was prepared and evaluated in the same manner as in Example 1.
・Uniaxially stretched low-density polyethylene film: 50 μm thick LDPE film manufactured by Ube Maruzen Polyethylene Co., Ltd., made by stretching Z481 to a MD direction stretching ratio of 2.5 times.

<Piercing strength test>
In order to confirm the influence of film structure on strength, a puncture strength test was conducted on the laminated film without the seal layer. That is, a puncture strength test was conducted on the laminated film (only the part in brackets in the figure) excluding the sealing layer among the films for isostatic pressing obtained in each example and the film of the comparative example.
The puncture strength test was conducted in accordance with JIS Z1707 (2019), and specifically, using a Tensilon universal testing machine (model: Autograph AGS-X) manufactured by Shimadzu Corporation, at 23°C and 50% Under RH conditions, a needle with a round tip (diameter 1 mmφ, R = 0.5 mm) was pierced into a fixed laminated film at a piercing speed of 50 mm/min, and the strength (N) when the needle penetrated was measured. .
The results are shown in Table 1. Note that since Example 2 and Example 3 differ only in the structure of the seal layer, the results in Table 1 are the same.

From a comparison between Examples and Comparative Examples, it was found that the laminated film having a high-density polyethylene layer had high puncture strength.
Comparing Example 4 and Example 5, although Example 4 had a thinner stretched film than Example 5, higher puncture strength was obtained. Therefore, a laminated film with higher puncture strength can be obtained by laminating films so that the stretching axes are in different directions, compared to when the films are laminated so that the stretching axes are in the same direction. was confirmed.
Further, when comparing Example 1 and Example 2, the result was that the extruded resin layer 11 using extrusion laminate had higher puncture strength than the adhesive resin film 12 using dry laminate. Example 1 is also environmentally friendly because no adhesive is used.

<Bag-making processing evaluation test>
The isostatic pressure forming films (including the sealing layer) obtained in Examples 1, 2, and 3 were cut into rectangles (200 mm x 200 mm) and processed using a three-sided seal bag making machine (BH-60HVLL manufactured by Totani Giken Co., Ltd.). The appearance and suitability of sealing were observed when vertical sealing was performed using .
During the bag manufacturing process, we checked for seepage of the extruded laminate layer, etc., wrinkles during pasting, etc., and ◎ indicates that no problems were found, 〇 indicates that there is no problem, and △ indicates that it can withstand practical use. Items with problems were marked as ×.
Further, the heat-sealed portion was subjected to a tensile test (JIS-Z1707) using a Tensilon universal testing machine to measure the seal strength. The sealing portion was cut out into a strip of 15 mm width x 100 mm length, and the breaking strength measured at a tensile speed of 200 mm/min was defined as the seal strength.
The results are shown in Table 2.

From a comparison between Examples 2 and 3, it was found that by providing the outermost seal layer with a linear low-density polyethylene layer, the seal strength and bag-making processability were excellent.
Further, from a comparison between Examples 1 and 2, it was confirmed that the use of dry laminate between layers was superior in terms of bag-making processability, such as prevention of extruded resin stains.

In the present invention, the molding bag 10 and the isostatic pressing bag 10 correspond to the "isostatic isostatic pressing bag", the laminate layers 11 and 12 correspond to the "laminate layer", and the extruded resin layer 11 corresponds to the "laminate layer". The adhesive resin film 12 corresponds to the "adhesive resin film", the AC seal layer 14, the extrusion seal layer 15, and the film seal layer 16 correspond to the "seal layer", and the high density Polyethylene layer A corresponds to a "high-density polyethylene layer (A)" and high-density polyethylene layer B corresponds to a "high-density polyethylene layer (B)."

Although a preferred embodiment of the present invention is as described above, the present invention is not limited thereto. It will be appreciated that various other embodiments may be made without departing from the spirit and scope of the invention. Further, in this embodiment, the functions and effects of the configuration of the present invention are described, but these functions and effects are merely examples and do not limit the present invention.

10 Molded bag 11 Extruded resin layer (laminate layer)
12 Adhesive resin film (laminate layer)
14 AC seal layer (seal layer)
15 Extruded seal layer (seal layer)
16 Film seal layer (seal layer)
20 Laminate 30 PET film 40 Substrate A, B High-density polyethylene layer

Claims (10)

A film for isostatic pressure molding, consisting of a laminated film having a high-density polyethylene layer (A). The film for isostatic pressing according to claim 1, wherein the high-density polyethylene layer (A) is a uniaxially stretched film. The laminated film further includes a high-density polyethylene layer (B),
The high density polyethylene layer (B) is a uniaxially stretched film,
The film for isostatic pressing according to claim 2, wherein the stretching direction of the high-density polyethylene layer (A) and the stretching direction of the high-density polyethylene layer (B) are laminated in different directions. The laminated film further includes a laminate layer,
The isostatic pressing according to claim 3, wherein the laminate layer is an extruded resin layer containing polyethylene, and is laminated between the high-density polyethylene layer (A) and the high-density polyethylene layer (B). Film for. The laminated film further includes a laminate layer,
The film for isostatic pressing according to claim 3, wherein the laminate layer is an adhesive resin film, and is laminated between the high-density polyethylene layer (A) and the high-density polyethylene layer (B). . The laminated film further has a sealing layer,
The film for isostatic pressing according to claim 1, wherein the sealing layer is a resin layer made of polyethylene and is laminated on the outermost layer of the laminated film. The film for isostatic pressing according to claim 1, wherein the laminated film has a polyethylene resin content of 90% by weight or more. The film for isostatic pressing according to claim 1, wherein the laminated film contains the polyethylene resin of the film used for isostatic pressing. A bag for isostatic pressing made using the film for isostatic pressing according to claim 1. An isostatic pressing method comprising pressurizing an object to be packaged using the isostatic pressing film according to claim 1.