JP4398839B2 - Method for producing multilayer film and multilayer film obtained thereby - Google Patents

Description

  The present invention relates to a method for producing a multilayer film including a structure in which a resin layer containing polyimide is directly laminated, and a multilayer film obtained by this production method, and in particular, a resin layer containing a high heat-resistant polyimide. The present invention relates to a method for producing a multilayer film that can be suitably used for the production of an adhesive multilayer film including a structure in which a resin layer containing a thermoplastic polyimide is laminated on at least one surface, and an adhesive multilayer film obtained thereby. Is.

  In recent years, the demand for various printed circuit boards has increased with the reduction in weight, size and density of electronic products. Among these printed boards, the demand for flexible wiring boards is growing. The flexible wiring board is also referred to as a flexible printed wiring board (FPC). The flexible wiring board has a structure in which a circuit made of a metal layer is formed on an insulating film.

  The above-mentioned flexible wiring board is generally formed of various insulating materials, a flexible insulating film is used as a substrate, and a metal foil is bonded to the surface of the substrate by heating and pressure bonding via various adhesive materials. Manufactured by. A polyimide film or the like is preferably used as the insulating film, and an epoxy or acrylic thermosetting adhesive is generally used as the adhesive material. A flexible wiring board using such a thermosetting adhesive has a three-layer structure of substrate / adhesive material / metal foil, and is hereinafter referred to as “three-layer FPC” for convenience of explanation.

  The thermosetting adhesive used for the three-layer FPC has an advantage that it can be bonded at a relatively low temperature. However, in the future, it is assumed that demands for various characteristics such as heat resistance, flexibility, and electrical reliability will be severer for flexible wiring boards. However, in a three-layer FPC using a thermosetting adhesive, It is considered difficult to sufficiently meet such demands.

  On the other hand, a flexible wiring board in which a metal layer is directly provided on an insulating film and a flexible wiring board using a thermoplastic polyimide as an adhesive layer have been proposed. Since these flexible wiring boards are in a state in which a metal layer is directly formed on an insulating substrate, they are hereinafter referred to as “two-layer FPC” for convenience of explanation. This two-layer FPC has characteristics superior to those of the three-layer FPC, and can sufficiently meet the demands for the various characteristics described above, so that it is industrially useful, and demand is expected to increase in the future.

  The two-layer FPC is manufactured using a flexible metal-clad laminate having a structure in which a metal foil is laminated on a substrate. Examples of the method for producing the flexible metal-clad laminate include a casting method, a metalizing method, and a laminating method. The casting method is a method in which polyamic acid, which is a polyimide precursor, is cast and applied onto a metal foil and then imidized. The metalizing method is a method in which a metal layer is directly provided on a polyimide film by sputtering or plating. The laminating method is a method in which an adhesive film in which a thermoplastic polyimide layer is provided on at least one surface of a high heat resistant polyimide layer is bonded to a metal foil.

  Among these, the lamination method is excellent in that the thickness range of the metal foil that can be handled is wider than that of the casting method and the apparatus cost is lower than that of the metalizing method. As an apparatus for performing the laminating method, a hot roll laminating apparatus or a double belt press apparatus for continuously laminating a roll-shaped material is used.

  In the flexible metal-clad laminate produced by the laminating method, an adhesive film in which a layer of a resin composition containing a thermoplastic polyimide is provided on at least one surface of a polyimide film is widely used as a substrate.

  Typical methods for producing the adhesive film include a coating method and a heat laminating method. The coating method is a method in which a solution of a resin composition containing a thermoplastic polyimide or a solution of a precursor thereof is applied to one side or both sides of a film made of high heat resistant polyimide and dried. The thermal laminating method is a method in which one side or both sides of a film made of high heat-resistant polyimide is heated and bonded to a film made of thermoplastic polyimide for production. The adhesive film obtained by these manufacturing methods needs to improve adhesion between layers made of different kinds of polyimides. However, since different types of polyimides generally have poor adhesion, it is often difficult to obtain an adhesive film having sufficient strength.

  As a technique for improving the adhesion between different types of polyimides, different polyimides are used by using an organic solvent solution containing polyimide or its precursor polyamic acid (polyamic acid) (referred to as polyimide varnish for convenience of explanation). A technique of laminating a resin layer containing bismuth is known. In this technique, a polyimide varnish is usually cast on a smooth support (base material) to form a laminated liquid film (referred to as a multilayer liquid film for convenience of explanation), and then the resulting multilayer liquid is obtained. A multilayer film is produced by heating and drying the film (see, for example, Patent Documents 1 and 2).

  The method for forming the multilayer liquid film is not particularly limited, but a coextrusion film forming method for extruding different types of polyimide varnish using a multilayer die, a method using a slide die (see Patent Document 3), and the like are different. For example, a method of sequentially applying various types of polyimide varnishes.

By the way, polyimide can be obtained by dehydration conversion reaction (imidation) of polyamic acid. As imidization methods, there are a thermal curing method only by heat treatment and a chemical curing method in which a dehydrating agent and a catalyst are added. Are known. In the production of polyimide, it is known that the chemical cure method is significantly more productive than the thermal cure method.
Japanese Patent No. 2946416 (registered on July 2, 1999 (1999), published publication: JP-A-11-99554, published on April 13, 1999 (1999)) Japanese Patent Laid-Open No. 7-214636 (published August 15, 1995) JP 2003-342390 A (published on December 3, 2003 (2003))

  However, when a polyimide multi-layer film is manufactured by employing a chemical curing method, there arises a problem that the adhesion between the resin layers is lowered.

  Specifically, when the multilayer liquid film contains a liquid film to which a dehydrating agent and a catalyst are added, when the multilayer liquid film is heated and dried, the solvent exudes from the liquid film to which the dehydrating agent and the catalyst have been added, and imidization occurs. Accumulate between subsequent resin layers. This accumulation of the solvent lowers the adhesive strength between adjacent resin layers, and as a result, induces peeling of the resin layer. Therefore, it greatly hinders the production of the multilayer film, and causes problems such as a decrease in production efficiency, a decrease in yield, and a decrease in the quality of the resulting multilayer film.

  The present invention has been made in view of the above problems, and its purpose is to efficiently produce a multilayer film composed of a plurality of resin layers containing polyimide even if imidization is performed by a chemical curing method. It is an object of the present invention to provide a technique capable of producing a high-quality multilayer film.

  As a result of intensive studies in view of the above problems, the present inventors have determined that a plurality of liquid films are formed on a support using two or more types of polyimide varnish (an organic solvent solution of polyimide or polyamic acid) in the process of producing a multilayer film. After forming the film, it is found that the adhesiveness between the resin layers after imidization can be improved by partially deforming by applying external force in the vicinity of the end in the width direction of the liquid film, The present invention has been completed.

  That is, the method for producing a multilayer film according to the present invention is a method for producing a multilayer film having a structure in which a plurality of resin layers containing polyimide are directly laminated, and contains at least polyimide or a precursor thereof. A liquid film laminating step of laminating a liquid film composed of each resin solution on the support surface using a plurality of types of resin solutions, and a liquid in a laminated state obtained in the liquid film laminating step It is characterized by including an end portion deformation step of causing deformation by applying an external force to the end region in the width direction of the film.

  In the manufacturing method of the multilayer film, it is preferable to apply an external force by pressurizing an end region in the width direction of the liquid film in the end deformation step, and in the end deformation step, the liquid in the end region is applied. More preferably, an external force is applied by ejecting a fluid onto the surface of the membrane.

  Further, in the above manufacturing method, a self-supporting step of forming a gel multilayer film having self-supporting property by drying and / or heating the liquid film in a laminated state, which is performed after the end portion deformation step. And may further include a firing step of firing the liquid film or the gel multilayer film in the laminated state. Moreover, a chemical dehydrating agent and a catalyst may be contained in at least one of the liquid film baked in the baking step or the gel film in which the liquid film is self-supported. As a result, at least one liquid film is imidized by a chemical cure method.

  In the said manufacturing method, it is preferable to form the liquid film in a laminated state using a multilayer die at a liquid film lamination process. In addition, examples of the obtained multilayer film include a structure in which a resin layer containing a thermoplastic polyimide is laminated on at least one surface of a resin layer containing a high heat resistant polyimide.

  The present invention also includes a multilayer film produced by the method for producing a multilayer film. Examples of the multilayer film include a multilayer film having a structure in which a heat-resistant layer containing a high heat-resistant polyimide and a structure in which an adhesive layer containing a thermoplastic polyimide is laminated on at least one surface of the heat-resistant layer, that is, an adhesive film. be able to.

  In the present invention, at the stage before complete imidization, the end is partially deformed by applying a physical external force to the end in the width direction of the liquid film. Therefore, even if a chemical curing method is employed as an imidization method, it is possible to improve the adhesion strength between resin layers containing polyimide. As a result, it is possible not only to improve the quality of the resulting multilayer film, but also to achieve significantly higher productivity than conventional manufacturing methods. Therefore, according to the present invention, for example, an adhesive multi-layer film (adhesive film) used for a two-layer FPC can be efficiently produced.

An embodiment of the present invention will be described as follows. However, the present invention is not limited to this, and can be implemented in various modifications within the scope described.
(I) Method for producing multilayer film according to the present invention The method for producing a multilayer film according to the present invention is a method for producing a multilayer film having a structure in which a plurality of resin layers containing polyimide are directly laminated, Using at least two kinds of solutions containing a polyimide resin and / or a precursor thereof, forming a liquid film of a plurality of layers on a base material, and having a manufacturing process of heating and drying the obtained liquid film, The vicinity of the end in the width direction of the liquid film is physically deformed.

If it divides into a specific process about the manufacturing method concerning this invention, it can divide into four processes, for example, a liquid film formation process, an edge part deformation process, a self-supporting process, and a baking process. Therefore, the present invention will be specifically described below based on the above steps.
(I-1) Liquid film forming step In the liquid film forming step, a plurality of types of resin solutions containing at least polyimide or a precursor thereof are used, and a liquid film made of each resin solution is laminated on the surface of the support. It is a process to do. Here, the liquid film in the present invention refers to a layer of a film-like resin solution formed using a resin solution containing polyimide or a precursor thereof, and by applying the resin solution to the surface of the support. Can be formed. In addition, the liquid film in the obtained laminated state is referred to as a multilayer liquid film for convenience.

  The support (base material) for forming the liquid film is not particularly limited as long as it has a surface on which the resin solution can be formed into a film shape, but the use of the finally obtained multilayer film The shape and the like may be set in consideration of the above. Specifically, for example, since the multilayer film obtained in the present invention can be used as an adhesive film as described later, the surface thereof is preferably as smooth as possible. In consideration of the productivity of the liquid film or the multilayer film, the shape of the support is preferably an endless belt or a drum. Moreover, although the material of a support body is not specifically limited, Generally, metals, such as stainless steel, can be mentioned.

  The multilayer liquid film formed on the surface of the support has a laminated structure, but the method for forming the multilayer liquid film is not particularly limited, and a known method can be used. Specifically, for example, a method using a multilayer die, a method using a slide die, a method of arranging a plurality of single-layer dies, a method of combining a single-layer die with spray coating or gravure coating, and the like can be given. Among these methods, the method using a multilayer die is particularly preferable in consideration of the productivity of the multilayer film and the maintenance property of the liquid film forming means. By using a multi-layer die, a multi-layer liquid film can be formed substantially in one stage, and the complexity of maintenance can be avoided. As the multi-layer die, a multi-manifold system, a feed block system, a mixing system of both, and the like are known, but any system may be adopted.

  As described above, the resin solution used in the liquid film forming step only needs to contain polyimide or a precursor thereof. Specific examples of the resin solution will be described in detail in the section (II) described later. In addition, the said resin solution may be called a polyimide varnish for convenience of explanation.

  When the resin component contained in the resin solution is polyamic acid (polyamic acid) which is a polyimide precursor, it is necessary to imidize a layer (liquid film) formed with the resin solution, as will be described later. Among the imidization methods, it is preferable to use a chemical curing method (detailed in the section (I-4) described later) in consideration of productivity and the like. Therefore, although depending on the configuration and application of the multilayer film to be obtained, it is preferable that at least one of the multilayer liquid films contains a chemical dehydrating agent and a catalyst. In other words, it is preferable to contain a chemical dehydrating agent and a catalyst (collectively referred to as a chemical curing agent) in advance in at least one of the resin solutions for forming a liquid film in a laminated state. Thereby, imidation by a chemical cure method can be advanced efficiently.

  The chemical dehydrating agent and the catalyst (chemical curing agent) may be added in advance to the resin solution, and a liquid film may be formed using this. The method for adding the chemical curing agent is not particularly limited, and examples thereof include a method of adding it as a solution (or dispersion). The solvent used in the chemical curing agent solution is not particularly limited, and may be added as a solution using the same organic polar solvent as that used in the resin solution, or if there is another preferable solvent. It may be used. Details of the chemical curing agent will be described in the section (I-4) below.

The thickness, size, and the like of the liquid film to be formed are not particularly limited, and appropriate conditions may be set according to the use of the multilayer film to be finally obtained. In Examples described later, a resin solution containing a precursor of a high heat resistant polyimide (high heat resistant polyimide varnish) and a resin solution containing a thermoplastic polyimide or a resin solution containing a precursor of a thermoplastic polyimide (thermoplastic polyimide varnish) Are supplied to a multi-manifold co-extrusion multilayer die having a lip width of 650 mm, and both solutions are extruded as a two-layer liquid film from a discharge port of the multilayer die onto a support.
(I-2) End Deformation Step In the end deformation step, deformation is caused by applying an external force to the end region in the width direction of the multilayer liquid film obtained in the liquid film lamination step. In the present invention, by performing this edge deformation step, it becomes possible to maintain a good adhesion state between the resin layers containing polyimide in the obtained multilayer film, and the occurrence of peeling between the resin layers is effective. It is possible to avoid it.

  The “end region in the width direction” in the multilayer liquid film refers to a region including a width of 5 mm from the end in the width direction of the liquid film toward the inside thereof. In the present invention, at least the end region may be deformed by applying an external force. Therefore, the region to which the external force is applied may include a region having a width of 5 mm inside from the end. However, if the area to which the external force is applied is too wide, for example, the area that can be used when the multilayer film is used as an adhesive film is reduced. The width is preferably 5 mm or more and less than 100 mm, more preferably 5 mm or more and less than 80 mm.

  The method for applying the external force is not particularly limited, and examples thereof include a method for pressurizing the end region in the width direction of the liquid film. By applying an external force in the form of pressurization, it is possible to effectively avoid the occurrence of peeling between resin layers without greatly affecting the laminated structure as a multilayer film.

  The pressurizing method (external force applying method) performed in the end deformation step is not particularly limited, and is a method of injecting fluid onto the liquid film surface in the end region, rubber or resin for the end region. And a method of bringing a metal plate or roll into contact with each other continuously or intermittently. Among these, a method of ejecting fluid is more preferable. By ejecting the fluid, it is possible to avoid damaging the support and to simplify the configuration of the pressurizing means.

  The fluid used in the method of injecting the fluid is not particularly limited as long as it can effectively pressurize the end region by spraying on the liquid film surface. Specifically, for example, Examples thereof include gas such as air, nitrogen gas and helium gas; liquid such as organic solvent and water; Among these, gas is preferable because it is easy to control injection and the configuration of the injection means can be simplified, and air is more preferable because it is inexpensive.

The fluid ejection conditions are not particularly limited as long as the conditions allow the end region to be deformed while sprayed on the end region. For example, in the embodiments described later, air or nitrogen gas is selected as the fluid, and is ejected from the discharge port of 1 mm × 30 mm at a pressure of 19.6 N / cm ² (2 kgf / cm ² ). Note that the multilayer liquid film to be sprayed at this time is a multilayer liquid film formed so as to finally become an adhesive film (multilayer film) composed of a 3 μm adhesive layer and an 18 μm heat-resistant layer.

In addition, the state of deformation when the end region of the multilayer liquid film is deformed in the end deformation step is not particularly limited, and the shape may be changed from the initial shape of the formed multilayer liquid film. That's fine. Specifically, for example, as shown in FIG. 1, a state where the end region is deformed so as to be crushed can be exemplified. In FIG. 1, the multilayer liquid film 20 including the first liquid film 11 and the second liquid film 12 formed by being laminated on the surface of the first liquid film 11 is indicated by a one-dotted line in the drawing. The state which injected the fluid from the discharge outlet 19 to the edge part area | region is shown. Thereby, the edge part area | region 18 of the 2nd liquid film 12 will be in the state crushed by the jet pressure of the fluid, as shown with the dashed-two dotted line in a figure. By applying such deformation, the adhesive state of each resin layer can be improved in the resulting multilayer film.
(I-3) Self-supporting step The self-supporting step is performed after the edge deformation step, and a gel multilayer film having self-supporting properties is formed by drying and / or heating the liquid film in a laminated state. To do. The term “having self-supporting property” as used herein means that the liquid film becomes a gel-like film by drying and / or heating to partially imidize the polyamic acid or evaporate the solvent. In other words, the self-supporting gel-like film is a polyamic acid solution or a polyimide solution, or when a polyimide film is formed by heating and drying these solutions with additives added as necessary. The organic solvent or reaction product (these are referred to as residual components) in a part is left in the polyimide film.

  The specific self-supporting step is not particularly limited, and the multilayer liquid film extruded from the multilayer die and formed on the smooth support is dried and / or heated to obtain a multilayer liquid film. At least a part of the solvent may be volatilized (evaporated) or partially imidized. Here, the conditions (drying method, drying temperature, drying time, etc.) when heating and drying are not particularly limited, and the solvent can be evaporated or partially imidized to such an extent that self-supporting properties can be exhibited. Such a condition may be used.

In general, the drying method is the simplest method by heating and / or blowing. If the temperature at the time of the heating is too high, the solvent may be volatilized (evaporated) rapidly, and traces of the volatilization may remain. Since this trace becomes a factor of forming minute defects in the finally obtained multilayer film, it is preferable to heat at a temperature that does not cause rapid volatilization. Specifically, the boiling point of the solvent used for the resin solution is preferably less than + 50 ° C. In addition, although drying time is not specifically limited, Generally, it is preferable to exist in the range of 1 to 60 minutes. Within this range, an efficient drying process is possible.
(I-4) Firing step In the firing step, the gel multilayer film is peeled off from the surface of the support, and the gel multilayer film is sufficiently heated at a high temperature to substantially remove the solvent and advance imidization. . Thereby, the multilayer film concerning this invention can be obtained. When a multilayer film is used as an adhesive film, the imidization rate may be intentionally lowered and / or a solvent may be left for the purpose of improving the melt fluidity of the adhesive layer.

  As the method for performing the imidization (dehydration conversion reaction from polyamic acid), two methods are most widely known: a thermal curing method that is performed only by heat and a chemical curing method that uses a chemical curing agent. Any method may be adopted, but in view of production efficiency, it is particularly preferable to employ a chemical curing method. If it is a chemical curing method, it becomes possible to realize higher productivity.

  The chemical curing agent includes a dehydrating agent and a catalyst. The dehydrating agent is not particularly limited as long as it is a dehydrating ring-closing agent for polyamic acid, and specific examples of the main component include, for example, aliphatic acid anhydrides, aromatic acid anhydrides, N, N′-dialkylcarbodiimide, lower aliphatic halide, halogenated lower aliphatic acid anhydride, arylsulfonic acid dihalide, thionyl halide, or a mixture of two or more thereof can be preferably used. Among these compounds, aliphatic acid anhydrides and aromatic acid anhydrides can be particularly preferably used.

  The catalyst is not particularly limited as long as it is a component having an effect of promoting dehydration and ring closure of a chemical dehydrating agent on polyamic acid. Specifically, for example, an aliphatic tertiary amine, Aromatic tertiary amines and heterocyclic tertiary amines can be used. Among these compounds, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, and β-picoline can be particularly preferably used.

  The amount of the chemical dehydrating agent and the catalyst used is not particularly limited as long as it can be imidized to a desired degree. However, the chemical dehydrating agent is added to the polyamic acid solution to which the chemical dehydrating agent and the catalyst are added. It is preferably in the range of 0.5 to 5 mol, more preferably in the range of 0.7 to 4 mol, with respect to 1 mol of the amic acid unit in the contained polyamic acid. The catalyst is preferably in the range of 0.05 to 3 mol with respect to 1 mol of the amic acid unit in the polyamic acid contained in the polyamic acid solution to which the chemical dehydrating agent and the catalyst are added. More preferably in the range of 2 to 2 mol. If the amount of the chemical dehydrating agent and the catalyst used is less than the above range, chemical imidization may be insufficient, and may break during firing or mechanical strength may decrease. Moreover, when the usage-amount of a chemical dehydrating agent and a catalyst exceeds the said range, progress of imidation will become quick too much and it may become difficult to cast into a film form.

  Although the specific conditions of the said baking process are not specifically limited, It is preferable that the highest ultimate temperature of a film exists in the range of 250-600 degreeC, and it is more preferable that it exists in the range of 300-350 degreeC. . Within this temperature range, the polyamic acid can be sufficiently heat-treated for efficient imidization. There is no particular limitation on the imidation time (heating time), and it is sufficient to take a time sufficient for the imidization and drying to be substantially completed. Generally, it may be within a range of about 1 to 600 seconds.

  Here, in the firing step, it is preferable to perform imidization treatment while applying tension to the gel multilayer film. As a result, the production efficiency can be improved and the quality of the resulting multilayer film can be improved. The tension applied during imidization is preferably in the range of 1 to 15 kg / m, and more preferably in the range of 5 to 10 kg / m. If the tension is smaller than the above range, sagging or meandering may occur during film conveyance, and problems such as wrinkling during winding or inability to uniformly wind may occur. On the other hand, when larger than the said range, since it heats at high temperature in the state where strong tension was applied, the dimension characteristic of the obtained multilayer film may deteriorate.

In the manufacturing method according to the present invention, steps other than the above four steps may be included, or some of the steps may be omitted from the type of multilayer film to be obtained, manufacturing convenience, and the like. As another process, the resin solution preparation process which prepares a resin solution (polyimide varnish) in the front | former stage of a liquid film formation process can be mentioned, for example.
(II) An example of the multilayer film according to the present invention The multilayer film according to the present invention is manufactured by the above-described multilayer film manufacturing method, and has a structure in which a plurality of polyimide-containing resin layers are directly laminated. The configuration is not particularly limited as long as it is a configuration.

  Specific examples of the multilayer film according to the present invention include, for example, an adhesive film having a configuration in which an adhesive layer containing a thermoplastic polyimide is laminated on at least one surface of a heat resistant layer containing a high heat resistant polyimide. it can. In other words, as an example of the multilayer film according to the present invention, an adhesive film including a structure in which a resin layer containing a thermoplastic polyimide is laminated on at least one surface of a resin layer containing a high heat-resistant polyimide. Can do.

<Heat resistant layer>
The heat-resistant layer provided in the adhesive film contains polyimide, and may be any material that does not easily undergo thermal deformation at the temperature that is usually exposed in the process of processing using the adhesive film or in the form of the final product. The specific type of polyimide used is not particularly limited, but it is preferable to contain a high heat-resistant polyimide. The high heat resistance means that the shape of the film is maintained without melting when heated to a temperature range of about 450 to 500 ° C. in a state where the polyimide is formed into a film.

  The adhesive film can be suitably used for the production of a two-layer FPC. In this case, since the adhesive layer contains thermoplastic polyimide, a high temperature of at least 200 ° C. or higher is required in order to develop heat-fusibility. Need to add. Therefore, it is preferable that the heat-resistant layer contains a high heat-resistant polyimide capable of avoiding thermal deformation and exhibiting sufficient shape stability even under such a high temperature condition.

  Although it does not specifically limit as said high heat resistant polyimide, Non-thermoplastic polyimide resin can be mentioned. More specifically, various aromatic polyimides can be mentioned. The molecular structure and the like of the high heat-resistant polyimide used in the present invention are not particularly limited, but for preferred examples, the acid dianhydride component and diamine component which are monomer raw materials and the method for producing the polyimide are specifically described. Will be described in detail later.

  The heat-resistant layer preferably contains 90% by weight or more of non-thermoplastic polyimide, more preferably 95% by weight or more. In other words, the heat-resistant layer may contain components other than the high heat-resistant polyimide. In addition, the thickness of the said heat-resistant layer is not specifically limited, What is necessary is just to set appropriate thickness according to various conditions, such as a use of an adhesive film.

  Examples of the other components include various resins that can be blended with the high heat-resistant polyimide and that do not impair the physical properties of the heat-resistant layer, and various additives that improve various properties of the heat-resistant layer. Among these, in the present invention, it is preferable to add a filler. By adding the filler, various properties such as slidability, thermal conductivity, conductivity, corona resistance, loop stiffness, and the like of the obtained adhesive film can be improved.

  Although the filler used by this invention is not specifically limited, The inorganic filler which consists of various inorganic compounds can be mentioned. More specifically, oxides such as silica, mica, titanium oxide, and alumina; inorganic nitrides such as silicon nitride and boron nitride; and phosphate compounds such as calcium hydrogen phosphate and calcium phosphate.

  The particle size of the filler is not particularly limited because it is determined by the film characteristics to be modified and the type of filler to be added, etc., but generally the average particle size is in the range of 0.05 to 100 μm. It is sufficient that it is within the range of 0.1 to 75 μm, more preferably within the range of 0.1 to 50 μm, and even more preferably within the range of 0.1 to 25 μm. If the particle size is below this range, the modification effect is less likely to appear. If the particle size is above this range, the surface properties may be greatly impaired or the mechanical properties may be greatly deteriorated.

  The amount of filler added is also not particularly limited because it is determined by the film properties to be modified, the particle size of the filler, and the like, but is generally 0.01-100 parts by weight with respect to 100 parts by weight of polyimide. Within a range of 0.01 to 90 parts by weight, and more preferably within a range of 0.02 to 80 parts by weight. If the amount of filler added is less than this range, the effect of modification by the filler hardly appears, and if it exceeds this range, the mechanical properties of the film may be greatly impaired.

  The method for adding the filler is not particularly limited. Specifically, for example, (1) the addition to the polymerization reaction solution before or during the polymerization of the polyamic acid, (2) after the completion of the polymerization of the polyamic acid, 3 Examples of the method include kneading the filler using the present roll and the like, (3) separately preparing a dispersion containing the filler, and mixing this with the polyamic acid solution.

  Among these methods, (3) a method in which a dispersion containing a filler is mixed with a polyamic acid solution is preferable. If this method is adopted, the filler can be mixed immediately before forming the gel film, so that the possibility of the filler remaining in the adhesive film production line and the accompanying filler mixing can be reduced most. .

  The method for preparing the dispersion containing the filler is not particularly limited, and it may be prepared as a dispersion by adding the filler to be used to an appropriate solvent. The solvent is the same as the resin solution (polyimide varnish). It is preferable to use an organic polar solvent. Further, in order to disperse the filler satisfactorily and stabilize the dispersion state, additives such as a dispersant and a thickener may be used within a range that does not affect the film physical properties.

<High heat resistant polyimide>
The non-thermoplastic polyimide used as the high heat-resistant polyimide of the heat-resistant layer can be produced by producing polyamic acid as a precursor and imidizing it.

  Any known method can be used for producing the polyamic acid, and it is not particularly limited. Usually, the acid dianhydride component and the diamine component are dissolved in an organic solvent so as to be substantially equimolar amounts, and the polymerization of the acid dianhydride and the diamine is completed under controlled temperature conditions. Produced by stirring until. The polyamic acid obtained by this production method is an organic solvent solution (hereinafter referred to as a polyamic acid solution for convenience), and the concentration of the polyamic acid is usually in the range of 5 to 35% by weight, preferably 10 to 30% by weight. It is within the range. A concentration within this range provides a molecular weight and solution viscosity suitable for the present invention.

  As a method for polymerizing the polyamic acid, any known method and a combination thereof can be used. The characteristic of the polyamic acid polymerization method is the order of addition of the monomer components. Therefore, various physical properties of the polyimide obtained can be controlled by controlling the order of addition of the monomer components. Therefore, in the present invention, the addition order of the monomer components may be appropriately determined according to various physical properties required for the non-thermoplastic polyimide to be finally obtained. A monomer component may be added.

Thus, the polymerization method of the polyamic acid is not particularly limited, but examples of typical polymerization methods include the following methods. In addition, these methods may be used independently and can also be used combining partially.
1) After dissolving a diamine component in an organic polar solvent, a substantially equimolar acid dianhydride component is added to the diamine component, followed by stirring and reaction to polymerize.
2) An acid dianhydride component and a diamine component in an excessively small molar amount are dissolved in an organic polar solvent, stirred and reacted, and a prepolymer having acid anhydride groups at both ends is dissolved in an organic polar solvent. Get as. Subsequently, the diamine component is added to the prepolymer solution and stirred and polymerized so that the acid dianhydride component and the diamine component are substantially equimolar in all steps.
3) An acid dianhydride component and a diamine component in an excess molar amount are dissolved in an organic polar solvent and stirred and reacted to obtain a prepolymer having amino groups at both ends as a solution of the organic polar solvent. . Subsequently, the acid dianhydride component is added to the prepolymer solution and stirred and polymerized so that the acid dianhydride component and the diamine component are substantially equimolar in all steps.
4) After the acid dianhydride component is dissolved in an organic polar solvent, the diamine component is added so as to be substantially equimolar with the acid dianhydride component, followed by stirring and reaction.
5) A substantially equimolar mixture of an acid dianhydride component and a diamine component is dissolved in an organic polar solvent, and stirred and reacted for polymerization.

  In the above polymerization method, each monomer component (acid dianhydride component and / or diamine component) may be composed of only one type of compound or may be composed of two or more types of compounds. In addition, even when added to an organic polar solvent, these compounds may not dissolve due to the problem of solubility in the same solvent, but if they are evenly dispersed throughout the solvent, they are regarded as substantially dissolved. It's okay. Therefore, the term “dissolution” can be replaced with “dispersion” in the description of the methods 1) to 5).

  The organic polar solvent used for polymerizing the polyamic acid is not particularly limited as long as it is a solvent that dissolves the polyamic acid, and any solvent can be used. , N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like can be preferably used, and N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used. .

  As the monomer component used in the present invention, known compounds can be suitably used. In particular, in order to obtain a high heat-resistant polyimide, both the acid dianhydride component and the diamine component are both aromatic compounds. It is preferable that In other words, in the present invention, when producing a polyamic acid solution as a precursor of a high heat resistant polyimide, an aromatic tetracarboxylic dianhydride is used as the acid dianhydride component, and an aromatic diamine is used as the diamine component. Very preferred to use.

  The aromatic tetracarboxylic dianhydride that can be used as the acid dianhydride component in the present invention is not particularly limited, and specifically, for example, pyromellitic dianhydride, 2, 3, 6 , 7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxyphthalic dianhydride, 2,2-bis (3 4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) propane dianhydride, 1,1-bis (2, 3-dicarbo Ciphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ) Ethane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, p-phenylene bis (trimellitic acid monoester anhydride), ethylene bis (trimellitic acid monoester) Acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride), and analogs of these compounds. These compounds may be used singly or as a mixture in combination at an arbitrary ratio.

  Among the aromatic tetracarboxylic dianhydrides, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-oxyphthalic dianhydride, It is preferable to use at least one compound selected from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride. These four kinds of compound groups are referred to as “suitable acid dianhydride groups” for convenience of explanation. By polymerizing polyamic acid using these preferred acid dianhydride groups, various physical properties of the resulting adhesive film (especially heat-resistant layer) can be improved.

  The preferred amount of use in the case of using at least one compound selected from the above-mentioned preferred acid dianhydride group is preferably 60 mol% or less, and 55 mol% or less with respect to all the acid dianhydride components. It is more preferable that it is 50 mol% or less. If the amount of the compound selected from these preferred acid dianhydride groups exceeds the above upper limit, the glass transition temperature of the resulting polyimide film (or heat-resistant layer) becomes too low, or the storage modulus during heat is low. It may become too difficult to form the film itself.

  Moreover, when using pyromellitic dianhydride among the suitable acid dianhydrides group, the amount used is preferably in the range of 40 to 100 mol%, more preferably in the range of 45 to 100 mol%. More preferably, it is within the range of 50 to 100 mol%. By using pyromellitic dianhydride in this range, it is possible to easily maintain the glass transition temperature and heat storage modulus of the polyimide film obtained in a suitable range.

  The aromatic diamine that can be used as the diamine component in the present invention is not particularly limited. Specifically, for example, 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenylmethane, benzidine, 3 , 3'-dichlorobenzidine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 4,4'-diaminodiphenyl sulfide, 3, 3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfone, 4,4'-oxydianiline, 3,3'-oxydianiline, 3,4'-oxydianiline, 1,5-diaminonaphthalene, 4,4′-diaminodiphenyldiethylsilane, 4,4′-diaminodiphenylsilane, 4 4'-diaminodiphenylethylphosphine oxide, 4,4'-diaminodiphenyl N-methylamine, 4,4'-diaminodiphenyl N-phenylamine, 1,4-diaminobenzene (p-phenylenediamine), 1,3- Diaminobenzene, 1,2-diaminobenzene, bis {4- (4-aminophenoxy) phenyl} sulfone, bis {4- (4-aminophenoxy) phenyl} propane, bis {4- (3-aminophenoxy) phenyl} Sulfone, 4,4′-bis (4-aminophenoxy) biphenyl, 4,4′-bis (3-aminophenoxy) biphenyl, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4 -Aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,3-bis (3 Mention may be made of -aminophenoxy) benzene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone, and analogs of these compounds. These compounds may be used singly or as a mixture in combination at an arbitrary ratio.

  In the present invention, it may be preferable to use a diamine having a rigid structure (referred to as “rigid diamine” for convenience of explanation) as the diamine component. Specifically, the rigid structure here is the following general formula (1).

(Wherein R ¹ represents the following general formula group (2)

And R ^{2 in} the formula may be the same or different, but H—, CH ₃ —, —OH, may be selected from the group consisting of divalent aromatic groups represented by , —CF ₃ , —SO ₄ , —COOH, —CONH ₂ , Cl—, Br—, F—, and CH ₃ O—.
Can be mentioned.

  When the polyamic acid is polymerized using the rigid diamine, it is preferable to select a polymerization method (for example, a method 2) or 3) for obtaining a prepolymer among the polyamic acid polymerization methods described above. By using this polymerization method, a polyimide film having a high elastic modulus and a small hygroscopic expansion coefficient tends to be easily obtained.

  The molar ratio between the rigid diamine and the acid dianhydride in the case of obtaining the prepolymer is not particularly limited, but the rigid diamine: acid dianhydride component is within the range of 100: 70 to 100: 99 or 70: The range of 100 to 99: 100 is preferable, and the range of 100: 75 to 100: 90 or the range of 75: 100 to 90: 100 is more preferable. If the molar ratio of rigid diamine and acid dianhydride is below the above range, it is difficult to obtain an effect of improving the elastic modulus and hygroscopic expansion coefficient, and if it exceeds the above range, the linear expansion coefficient becomes too small or the tensile elongation becomes small. It may cause harmful effects such as

  Further, as the diamine component, the rigid diamine and a diamine having a flexible structure (referred to as “flexible diamine” for convenience of description) can be used in combination. When rigid diamine and flexible diamine are used in combination, the molar ratio of rigid diamine: flexible diamine is preferably in the range of 80:20 to 20:80, more preferably in the range of 70:30 to 30:70, and 60: More preferably within the range of 40-30: 70. If the ratio of rigid diamine used exceeds the above range, the tensile elongation of the resulting polyimide film (heat-resistant layer) tends to be small, and if it falls below this range, the glass transition temperature becomes too low, or the storage modulus during heat May become too low to form a film.

  The flexible diamine is a diamine having a flexible structure such as an ether group, a sulfone group, a ketone group, or a sulfide group, and more preferably the following general formula (3):

(In the formula, R ³ represents the formula group (4)

And R ^{4 in} the formula is the same or different and is H—, CH ₃ —, —OH, —CF ₃ , —SO ₄ , —. One group selected from the group consisting of COOH, —CONH ₂ , Cl—, Br—, F—, and CH ₃ O—. )
Can be mentioned.

  By imidizing the polyamic acid obtained by polymerizing the acid dianhydride component and the diamine component, determining the kind, blending ratio, etc. so as to obtain a film having the desired characteristics within the above range, A heat-resistant polyimide can be obtained. In the present invention, a layer containing this highly heat-resistant polyimide can be used as the heat-resistant layer. In addition, the organic solvent solution (polyamic acid solution) of the polyamic acid before imidation may be called a polyimide varnish for convenience as mentioned above. Further, since imidization has been described in detail in the section (I-4), a description thereof will be omitted.

<Adhesive layer and thermoplastic polyimide used therein>
The adhesive layer included in the adhesive film is not particularly limited as long as it contains thermoplastic polyimide and can exhibit adhesive properties under predetermined conditions. The thermoplastic polyimide layer used for the adhesive layer is not particularly limited as long as it can exhibit a significant adhesive force during lamination, and the molecular structure thereof is not particularly limited.

  In the adhesive layer, the content of the thermoplastic polyimide is not particularly limited, but it is preferable to contain 50% by weight or more of thermoplastic polyimide in order to develop a significant adhesive force. In other words, the adhesive layer may contain components other than the thermoplastic polyimide, similarly to the heat-resistant layer. In addition, the thickness of the said adhesive layer is not specifically limited, What is necessary is just to set appropriate thickness according to various conditions, such as a use of an adhesive film.

  The thermoplastic polyimide (in a broad sense) contained in the adhesive layer is not particularly limited. Specifically, for example, a thermoplastic polyimide (in a narrow sense), a thermoplastic polyamideimide, a thermoplastic polyetherimide, and a thermoplastic polyester. An imide or the like can be preferably used. Among these, a thermoplastic polyesterimide can be particularly preferably used from the viewpoint of low moisture absorption characteristics. In addition, the thermoplastic polyimide contained in the adhesive layer referred to in the claims refers to a broad sense having thermoplasticity including the above-mentioned various polyimides. Further, unless otherwise specified, the term “thermoplastic polyimide” used in the present specification indicates a broad term.

  Although the physical property of the thermoplastic polyimide used by this invention is not specifically limited, It is more preferable to set a glass transition temperature (Tg) in a predetermined range among various physical properties. Specifically, the thermoplastic polyimide used in the present invention preferably has a Tg in the range of 150 to 300 ° C, and more preferably in the range of 180 to 280 ° C. In addition, Tg can be calculated | required from the value of the inflexion point of the storage elastic modulus measured with the dynamic viscoelasticity measuring apparatus (DMA).

  If Tg is within the above range, the adhesive film according to the present invention can be laminated with a metal foil using an existing laminating apparatus, and the heat resistance of the resulting flexible metal-clad laminate is impaired. You can avoid that.

  Although the manufacturing method of the said thermoplastic polyimide is not specifically limited, Like the high heat resistant polyimide mentioned above, it can manufacture by superposing | polymerizing the precursor polyamic acid, and imidizing. The polymerization method of the polyamic acid is not particularly limited, and any known method can be employed. Specifically, the polyamic acid may be produced by selecting monomer raw materials, production conditions, and the like in the same manner as the high heat-resistant polyimide described above.

  In addition, the thermoplastic polyimide used in the present invention can adjust various characteristics by combining various monomer raw materials to be used in the same manner as the high heat-resistant polyimide, but generally, when the use ratio of rigid diamine increases, Tg Is high, and / or the storage elastic modulus at the time of heating is increased, which is not preferable because the adhesiveness and workability of the adhesive layer are lowered. Therefore, when the thermoplastic polyimide used in the present invention is produced and the rigid diamine is used in combination with the diamine component used for polymerizing the precursor polyamic acid, the rigid diamine in the total diamine component The use ratio (content ratio) is preferably 40 mol% or less, more preferably 30 mol% or less, and further preferably 20 mol% or less.

  A thermoplastic polyimide can be obtained by imidizing the polyamic acid obtained by polymerizing the monomer component as described above. In the present invention, a layer containing this thermoplastic polyimide can be used as an adhesive layer. In addition, the organic solvent solution (polyamic acid solution) of the polyamic acid before imidation may be called a polyimide varnish for convenience as mentioned above. Further, since imidization has been described in detail in the section (I-4), a description thereof will be omitted.

  Preferable specific examples of the thermoplastic polyimide include those obtained by polymerizing an acid dianhydride containing biphenyltetracarboxylic dianhydrides and a diamine having an aminophenoxy group.

  Further, the adhesive layer may contain a resin other than polyimide and various additives, like the heat-resistant layer. For example, a filler may be added as necessary as in the heat-resistant layer. Examples of the filler in this case include inorganic or organic fillers, but are not particularly limited, and specific types, amounts used, and the like may be appropriately selected according to physical properties required for the adhesive layer.

The multilayer film obtained by the present invention has two or more resin layers containing polyimide, and the resin layers are directly laminated. Until now, when the type of polyimide is different, the adhesiveness of each resin layer directly laminated was low, but in the present invention, the adhesiveness of each resin layer is increased by performing an end portion deformation step. It is possible. In other words, the multilayer film according to the present invention is a multilayer film in which a plurality of resin layers containing polyimide are directly laminated and the adhesiveness between the resin layers is excellent.
(III) Use of the present invention The use of the multilayer film according to the present invention is not particularly limited, and can be widely used for a laminate including a structure in which a plurality of resin layers containing polyimide are directly laminated. . Specifically, for example, it can be suitably used for a polyimide film used for various electronic components, and more specifically, it can be suitably used as an adhesive film including a heat-resistant layer and an adhesive layer.

  The heat-resistant layer contains the high heat-resistant polyimide described in the above section (II), and the adhesive layer contains the thermoplastic polyimide described in the same section (II). As a result, it is possible to obtain a polyimide film that can be suitably used as a substrate for a flexible wiring board such as an FPC and that can cope with the reduction in weight, size, and density of electronic products in recent years.

  The said adhesive film should just have the structure by which the said contact bonding layer was formed in the at least one surface of the said heat resistant layer and the said heat resistant layer. Therefore, examples of the adhesive film according to the present invention include a heat-resistant layer / adhesive layer two-layer structure and an adhesive layer / heat-resistant layer / adhesive layer three-layer structure. Furthermore, a structure in which a plurality of layers having a two-layer structure are stacked may be included, and a layer other than the heat-resistant layer and the adhesive layer may be included as necessary.

  When the multilayer film concerning this invention is an adhesive film, it can use suitably for manufacture of the laminated body containing a polyimide layer. That is, the laminated body manufactured using the said adhesive film may be contained in this invention. Although the specific structure of the said laminated body is not specifically limited, As a typical structure, the laminated body which has a structure formed by laminating | stacking a metal layer on the surface of an adhesive film can be mentioned. Although the manufacturing method of the said laminated body is not specifically limited, With respect to the adhesive film concerning this invention, the method of adhere | attaching metal foil to at least one surface by the lamination method, Preferably a hot roll lamination method is mentioned. Can do.

  Although it does not specifically limit as a metal layer laminated | stacked on the said adhesive film, When using the laminated body concerning this invention as a flexible metal-clad laminated board for an electronic device and an electrical equipment use, for example, copper Alternatively, a metal foil made of a copper alloy, stainless steel or an alloy thereof, nickel or a nickel alloy (including 42 alloy), aluminum, an aluminum alloy, or the like can be given. Moreover, in general flexible metal-clad laminates, copper foils such as rolled copper foil and electrolytic copper foil are frequently used, but these copper foils can also be preferably used in the present invention. In addition, the antirust layer, the heat-resistant layer, or the contact bonding layer may be apply | coated to the surface of these metal foil.

  Moreover, the flexible wiring board formed using the said adhesive film or the said laminated body may also be contained in this invention. Specifically, a flexible printed wiring board (FPC) can be mentioned. Although the specific manufacturing method of the said flexible printed wiring board is not specifically limited, Specifically, for example, a metal foil is laminated on an adhesive film, a pattern etching process is performed, and a desired pattern circuit is formed on the metal foil. The method of forming can be mentioned.

  The present invention will be described more specifically based on examples and comparative examples, but the present invention is not limited to this. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention.

[Synthesis Example of Polyamic Acid 1: Polyamic Acid as Precursor of High Heat-Resistant Polyimide]
239 kg of N, N-dimethylformamide (DMF) cooled to 10 ° C., 6.9 kg of 4,4′-oxydianiline (ODA), 6.2 kg of p-phenylenediamine (p-PDA), 2,2-bis [ After dissolving 9.4 kg of 4- (4-aminophenoxy) phenyl] propane (BAPP), 10.4 kg of pyromellitic dianhydride (PMDA) was added and stirred for 1 hour to dissolve. Further, 20.3 kg of benzophenonetetracarboxylic dianhydride (BTDA) was added to the obtained solution and stirred for 1 hour to dissolve, thereby preparing a reaction solution.

  A separately prepared DMF solution of PMDA (PMDA: DMF = 0.9 kg: 7.0 kg) was gradually added to the reaction solution, and the addition was stopped when the viscosity reached about 3000 poise. Thereafter, the mixture was stirred for 1 hour to obtain an organic solvent solution of polyamic acid which is a precursor of high heat resistant polyimide (referred to as high heat resistant polyimide varnish for convenience). The high heat resistant polyimide varnish had a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3500 poise.

[Synthesis Example 2 of Polyamic Acid: Polyamic Acid that is a Precursor of Thermoplastic Polyimide]
78 kg of DMF and 11.56 kg of BAPP were added to a reactor having a capacity of 300 liters, and 7.87 kg of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) was stirred under a nitrogen atmosphere. Slowly added. Subsequently, 0.38 kg of ethylene bis (trimellitic acid monoester acid anhydride) (TMEG) was added and stirred for 30 minutes in an ice bath. A solution in which 0.2 kg of TMEG was dissolved in 2 kg of DMF was separately prepared, and this was gradually added to the above reaction solution while paying attention to the viscosity and stirred. When the viscosity reached 3000 poise, addition and stirring were stopped to obtain an organic solvent solution of polyamic acid which is a precursor of thermoplastic polyimide (referred to as a thermoplastic polyimide varnish for convenience).

[Example 1]
Acetic anhydride was added as a chemical dehydrating agent and isoquinoline was added as a catalyst to the high heat resistant polyimide varnish obtained in Synthesis Example 1. The addition amount was 2.5 mol of acetic anhydride and 1 mol of isoquinoline with respect to 1 mol of the amic acid unit of the polyamic acid contained in the high heat-resistant polyimide varnish.

  Next, a highly heat-resistant polyimide varnish and a thermoplastic polyimide varnish were continuously extruded from the multi-manifold coextrusion multilayer die having a lip width of 650 mm onto the surface of the support and cast. The high heat-resistant polyimide varnish was extruded from the outer layer of the coextruded multilayer die, and the thermoplastic polyimide varnish was extruded from the inner layer of the coextruded multilayer die. In addition, a stainless steel endless belt was used as a support, and the polyimide varnish was extruded and cast while running at a position 20 mm below the coextrusion multilayer die.

After casting, 19.6 N / cm ² (19.6 N / cm ² (compressed air) is discharged from a 1 mm × 30 mm discharge port into a region (end region) having a width of 20 mm with reference to the end in the width direction of the obtained multilayer liquid film. The gas was ejected at a pressure of ² kgf / cm ² ). As a result, the vicinity of the end of the multilayer liquid film was physically deformed. Next, this multilayer liquid film was heated to 130 ° C. for 100 seconds to be converted into a self-supporting gel multilayer film. No peeling of the layer was observed in the gel multilayer film, and the appearance was also good.

  The gel multilayer film was peeled off from the endless belt, fixed to a tenter clip, and dried and imidized at 300 ° C. for 30 seconds, 400 ° C. for 50 seconds, and 450 ° C. for 10 seconds. Thus, an adhesive film as a multilayer film according to the present invention, which was a laminate of a 3 μm thermoplastic polyimide layer (adhesive layer) and an 18 μm high heat resistant polyimide layer (heat resistant layer), was obtained.

[Example 2]
The multilayer according to the present invention was performed in the same procedure as in Example 1 except that nitrogen gas having the same ejection pressure was used as the fluid instead of compressed air having an ejection pressure of 19.6 N / cm ² (2 kgf / cm ² ). An adhesive film as a film was obtained. No peeling of the layer was observed in the gel multilayer film before imidization, and the appearance was also good.

[Comparative Example 1]
An adhesive film was obtained by the same procedure as in Example 1 except that the fluid was not ejected near the end of the multilayer liquid film. In the gel multilayer film before imidization, part of the layer was observed to be peeled off. Further, when the gel multilayer film was peeled off from the endless belt and fixed to the tenter clip, fixing failure occurred at the above-mentioned peeling site. Therefore, an adhesive film having a good shape could not be obtained.

  Note that the present invention is not limited to the configurations described above, and various modifications are possible within the scope of the claims, and technical means disclosed in different embodiments and examples respectively. Embodiments and examples obtained by appropriately combining them are also included in the technical scope of the present invention.

  As described above, in the present invention, the adhesion strength between resin layers containing polyimide can be improved. Therefore, a multilayer film can be produced efficiently and a high-quality multilayer film can be obtained. Therefore, the present invention can be used not only in the field of producing various resin molded products represented by adhesive films and laminates using polyimide, but also using such adhesive films and laminates. It can also be applied to a wide range of fields related to the manufacture of electronic components.

It is a schematic diagram which shows the outline | summary of the edge part deformation | transformation process in the manufacturing method of the multilayer film concerning this invention.

Explanation of symbols

11 First liquid film 12 Second liquid film 18 End region 19 Discharge port 20 Multilayer liquid film

Claims (10)

A method for producing a multilayer film having a structure in which a plurality of resin layers containing polyimide are directly laminated,
At least, using a plurality of types of resin solutions containing polyimide or its precursor, including a liquid film laminating step of laminating a liquid film composed of each resin solution on the support surface,
The multilayer film further comprises an end deformation step that causes deformation by applying an external force to the end region in the width direction of the liquid film in the laminated state obtained in the liquid film laminating step. Production method.   2. The method for producing a multilayer film according to claim 1, wherein in the end deformation step, an external force is applied by pressurizing an end region in the width direction of the liquid film.   3. The method for producing a multilayer film according to claim 2, wherein, in the end portion deforming step, an external force is applied by spraying a fluid onto the surface of the liquid film in the end region.   And a self-supporting step of forming a gel multilayer film having self-supporting property by drying and / or heating the liquid film in a laminated state, which is performed after the end portion deforming step. The method for producing a multilayer film according to claim 1, 2 or 3.   Furthermore, the manufacturing method of the multilayer film of Claim 4 including the baking process which bakes the liquid film or gel multilayer film in the said lamination | stacking state.   6. The multilayer film according to claim 5, wherein at least one of the liquid film fired in the baking step or the gel film self-supporting the liquid film contains a chemical dehydrating agent and a catalyst. Manufacturing method.   The method for producing a multilayer film according to any one of claims 1 to 6, wherein in the liquid film lamination step, a liquid film in a laminated state is formed using a multilayer die.   The multilayer film obtained includes a structure in which a resin layer containing a thermoplastic polyimide is laminated on at least one surface of a resin layer containing a high heat-resistant polyimide. The manufacturing method of the multilayer film of Claim 1.   The multilayer film manufactured by the manufacturing method of the multilayer film of any one of Claim 1 thru | or 8. The multilayer film according to claim 9, comprising a structure in which a heat-resistant layer containing a high heat-resistant polyimide and an adhesive layer containing a thermoplastic polyimide are laminated on at least one surface of the heat-resistant layer.

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