JP2006159785A - Manufacturing method of adhesive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a multilayer film which enables a self-supporting film to be easily removed from a support while ensuring adhesion between a high heat-resistant polyimide and a thermoplastic poyimide of the multilayer film. <P>SOLUTION: The manufacturing method of the multilayer film having at least two kinds of polyimide layers is provided. The method comprises the process of casting at least two kinds of solutions, which are selected from a solution containing a polyimide resin precursor and a solution containing a polyimide resin, on a support by coextrusion and forming two or more layers, i.e., a plurality of layers. In at least one solution of the solutions used for the coextrusion a chemical dehydrating agent and a catalyst are contained, the chemical dehydrating agent and the catalyst are used in specific amounts, and the surface roughness Ra of the support is in the range of 0.002-1 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a multilayer film suitably used for flexible printed wiring boards and the like. More specifically, the present invention relates to a method for producing an adhesive film capable of suitably producing an adhesive film in which a thermoplastic polyimide layer is formed on at least one surface of a high heat resistant polyimide layer.

  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) or the like. The flexible laminate has a structure in which a circuit made of a metal foil is formed on an insulating film.

  The flexible laminate is generally formed of various insulating materials, and 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 also referred to as a three-layer FPC.

  The thermosetting adhesive used for the three-layer FPC has an advantage that it can be bonded at a relatively low temperature. However, as the requirements for various characteristics such as heat resistance, flexibility, and electrical reliability for FPC become stricter in the future, it is considered that the three-layer FPC using a thermosetting adhesive becomes difficult to cope with.

  On the other hand, FPCs in which a metal layer is directly provided on an insulating film and FPCs using thermoplastic polyimide as an adhesive layer have been proposed. Such an FPC is also called a two-layer FPC because a metal layer is directly formed on an insulating substrate. 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 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. As a method for producing this flexible metal-clad laminate, a metal layer is directly provided on a polyimide film by casting, applying a polyamic acid, which is a polyimide precursor, onto a metal foil, and then imidizing, sputtering, or plating. Examples thereof include a metallizing method and a laminating method in which a polyimide film and a metal foil are bonded via a thermoplastic polyimide.

  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 a device for laminating, a hot roll laminating device or a double belt press device for continuously laminating a roll-shaped material is used. Of these, the hot roll laminating method can be used more preferably from the viewpoint of productivity.

  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.

  Examples of the method for producing the adhesive film include a coating method, a heat laminating method, and a coextrusion method. The coating method is a method including a step of applying and drying a solution of a resin composition containing a thermoplastic polyimide or a solution of a precursor thereof on one or both sides of a film made of a high heat-resistant polyimide. 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 to produce. Moreover, the coextrusion-casting coating method creates a multilayer liquid film of different types of polyimide varnish using a multilayer die, and extrudes and dries the liquid film on a support to form a multilayer self-supporting film. Next, the self-supporting film is peeled off from the support and further dried and baked to obtain an adhesive film. Among these, the co-extrusion method is the most excellent method because it is excellent in productivity and has few steps of defects such as mixing of foreign substances because there are few steps.

  However, the conventional coextrusion-casting coating method has been studied on the premise of a so-called thermal curing method in which imidization is substantially performed only by heating. The thermal curing method has a problem in that productivity is low because the process of volatilization / removal of the solvent and imidization in the film forming process takes a very long time. The low productivity has the problem of increasing the total cost.

The present inventors have already found that it is effective to employ a so-called chemical curing method using a chemical dehydrating agent and a catalyst for imidization in order to solve the above-mentioned productivity problem. . As a result of further studies by the present inventors, it has been found that the use of a chemical cure method can solve the problem of productivity, but may cause a problem of delamination of each layer. That is, when an attempt is made to produce a multilayer film by the coextrusion-casting method, when the multilayer film is heated and dried, the solvent exudes from the layer to which the dehydrating agent and catalyst are added, and the high heat resistant polyimide layer and the heat The solvent accumulates between the plastic polyimide layers. The accumulation of the solvent induces delamination, which may cause a decrease in adhesive strength between the layers and difficulty in manufacturing an adhesive film.
No. 2946416 Japanese Patent Laid-Open No. 7-214637

  The present invention has been made in view of the above-mentioned problems, and the object thereof is an adhesive film in which a thermoplastic polyimide layer is formed on at least one surface of a high heat-resistant polyimide layer. It is providing the method of manufacturing suitably the adhesive film which improved the adhesiveness with a polyimide layer.

As a result of intensive studies in view of the above problems, the present inventors have uniquely found that easy peeling from a support can be achieved while ensuring adhesion between layers, and the present invention has been completed. It was. That is, this invention can solve the said subject with the following novel manufacturing methods.
1) A method for producing a multilayer film having at least two or more kinds of polyimide layers, wherein at least two kinds of solutions selected from a solution containing a polyimide resin precursor and a solution containing a polyimide resin are coextruded to support A solution containing a chemical dehydrating agent and a catalyst, and a solution containing the chemical dehydrating agent and the catalyst in at least one of the solutions used for the coextrusion. 0.5 to 4.0 moles of chemical dehydrating agent and 0.05 to 2.0 moles of catalyst with respect to 1 mole of amic acid unit in the polyamic acid contained in A method for producing a multilayer film, wherein Ra is in the range of 0.002 to 1 μm.
2) Surface roughness Ra of the said support body is 0.002-0.1 micrometer, The manufacturing method of the adhesive film of Claim 1 characterized by the above-mentioned.
3) The multilayer film is an adhesive film in which an adhesive layer containing a thermoplastic polyimide is laminated on at least one surface of a high heat resistant polyimide layer, and the solution used for the coextrusion contains a precursor of the high heat resistant polyimide. The method for producing a multilayer film according to claim 1 or 2, wherein the solution is a solution containing a precursor of a thermoplastic polyimide and / or a solution containing a thermoplastic polyimide.
4) 1.0-3.0 mol of chemical dehydrating agent and 0.05-1.0 mol of catalyst per 1 mol of amic acid unit in the polyamic acid contained in the solution containing the chemical dehydrating agent and catalyst. The method for producing a multilayer film according to claim 1, wherein the multilayer film is used.

  According to the present invention, it is possible to provide a method for producing a multilayer film capable of easily peeling the self-supporting film from the support while ensuring the adhesion between the high heat-resistant polyimide of the multilayer film and the thermoplastic polyimide. Become.

  Embodiments of the present invention will be described below.

  The method for producing a multilayer film according to the present invention is a method for producing a multilayer film having at least two kinds of polyimide layers, and at least two kinds selected from a solution containing a polyimide resin precursor and a solution containing a polyimide resin. And a step of casting the solution on a support by coextrusion to form two or more layers. Here, at least one of the solutions used for coextrusion contains a chemical dehydrating agent and a catalyst. 5 to 4.0 mol of chemical dehydrating agent and 0.05 to 2.0 mol of catalyst are used, and the support is characterized in that the surface roughness Ra is in the range of 0.002 to 1 μm. .

  The present inventors have already found a method that employs a chemical curing method when a multilayer film having a plurality of polyimide layers is produced by coextrusion, and further, each layer generated when the chemical curing method is used. In order to solve the problem of delamination, it has also been found that the amount of chemical curing agent added is adjusted. Although this succeeded in solving the problem of delamination, it was newly found that peeling may be difficult when the self-supporting film is peeled from the support. In the present invention, by further defining the surface roughness of the support, delamination of each layer does not occur, and a self-supporting film described later can be easily peeled off from the support. Can be obtained.

  When the surface roughness of the support exceeds the above range, the surface roughness of the finally obtained adhesive film increases, and when a flexible metal-clad laminate is produced using the adhesive film, Swelling or the like may occur. When the surface roughness of the support is lower than the above range, there may be a problem that the self-supporting film cannot be easily peeled off from the support or the cost for surface processing of the support increases. Hereinafter, description will be given based on an example of the embodiment.

<High heat resistant polyimide layer>
The high heat resistant polyimide layer according to the present invention is not particularly limited in its molecular structure and thickness as long as it contains 90 wt% or more of a non-thermoplastic polyimide resin. The non-thermoplastic polyimide used for the high heat resistant polyimide layer is manufactured using polyamic acid as a precursor. Any known method can be used as a method for producing the polyamic acid, and usually, the aromatic tetracarboxylic dianhydride and the aromatic diamine are controlled by dissolving substantially equimolar amounts in an organic solvent. It is produced by stirring under temperature conditions until the polymerization of the acid dianhydride and diamine is completed. These polyamic acid solutions are usually obtained at a concentration of 5 to 35 wt%, preferably 10 to 30 wt%. When the concentration is in this range, an appropriate molecular weight and solution viscosity are obtained.

As the polymerization method, any known method and a combination thereof can be used. The characteristic of the polymerization method in the polymerization of polyamic acid is the order of addition of the monomers, and the physical properties of the polyimide obtained can be controlled by controlling the order of addition of the monomers. Therefore, in the present invention, any method of adding monomers may be used for the polymerization of polyamic acid. The following method is mentioned as a typical polymerization method. That is,
1) A method in which an aromatic diamine is dissolved in an organic polar solvent and this is reacted with a substantially equimolar amount of an aromatic tetracarboxylic dianhydride for polymerization.
2) An aromatic tetracarboxylic dianhydride is reacted with a small molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having acid anhydride groups at both ends. Then, the method of superposing | polymerizing using an aromatic diamine compound so that an aromatic tetracarboxylic dianhydride and an aromatic diamine compound may become substantially equimolar in all the processes.
3) An aromatic tetracarboxylic dianhydride is reacted with an excess molar amount of an aromatic diamine compound in an organic polar solvent to obtain a prepolymer having amino groups at both ends. Subsequently, after adding an aromatic diamine compound here, using the aromatic tetracarboxylic dianhydride so that the aromatic tetracarboxylic dianhydride and the aromatic diamine compound are substantially equimolar in all steps. How to polymerize.
4) A method in which an aromatic tetracarboxylic dianhydride is dissolved and / or dispersed in an organic polar solvent and then polymerized using an aromatic diamine compound so as to be substantially equimolar.
5) A method in which a substantially equimolar mixture of aromatic tetracarboxylic dianhydride and aromatic diamine is reacted in an organic polar solvent for polymerization.
And so on. These methods may be used singly or in combination.

  In the present invention, the polyamic acid obtained by using any of the above polymerization methods may be used, and the polymerization method is not particularly limited.

  In this invention, it is also preferable to use the polymerization method which obtains a prepolymer using the diamine component which has a rigid structure mentioned later. By using this method, a polyimide film having a high elastic modulus and a small hygroscopic expansion coefficient tends to be easily obtained. The molar ratio of the diamine having a rigid structure and the acid dianhydride used in preparing the prepolymer in the present method is 100: 70 to 100: 99 or 70: 100 to 99: 100, and further 100: 75 to 100: 90 or 75: 100-90: 100 is preferable. When this ratio is less than the above range, it is difficult to obtain the effect of improving the elastic modulus and the hygroscopic expansion coefficient, and when it exceeds the above range, there are cases where the linear expansion coefficient becomes too small or the tensile elongation becomes small.

  Here, the material used for the polyamic acid composition concerning this invention is demonstrated.

  Suitable tetracarboxylic dianhydrides that can be used in the present invention are pyromellitic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyltetra. Carboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′- Benzophenone tetracarboxylic dianhydride, 4,4′-oxyphthalic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 3,4,9,10-perylenetetracarboxylic acid Dianhydride, bis (3,4-dicarboxyphenyl) propane dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxy) Phenyl) eta Dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) ethane dianhydride, oxydiphthalic dianhydride, bis (3,4-dicarboxyphenyl) Sulfone dianhydride, p-phenylenebis (trimellitic acid monoester acid anhydride), ethylene bis (trimellitic acid monoester acid anhydride), bisphenol A bis (trimellitic acid monoester acid anhydride) and the like These can be used alone or in a mixture of any proportion.

  Among these acid dianhydrides, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 4,4′-oxyphthalic dianhydride, 3,3 ′ It is preferable to use at least one selected from 4,4'-biphenyltetracarboxylic dianhydride.

  Among these acid dianhydrides, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxyphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetra The preferred amount of use in the case of using at least one selected from carboxylic dianhydrides is 60 mol% or less, preferably 55 mol% or less, more preferably 50 mol% or less, based on the total acid dianhydrides. 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 4,4′-oxyphthalic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride When using at least one kind, if the amount used exceeds this range, the glass transition temperature of the polyimide film may become too low, or the storage elastic modulus at the time of heating may become too low, making film formation itself difficult. Therefore, it is not preferable.

  Moreover, when using pyromellitic dianhydride, the preferable usage-amount is 40-100 mol%, More preferably, it is 45-100 mol%, Most preferably, it is 50-100 mol%. By using pyromellitic dianhydride in this range, the glass transition temperature and the storage elastic modulus at the time of heating can be easily maintained in a range suitable for use or film formation.

  Suitable diamines that can be used in the polyamic acid composition that is a precursor of the non-thermoplastic polyimide according to the present invention include 4,4′-diaminodiphenylpropane, 4,4′-diaminodiphenylmethane, benzidine, and 3,3 ′. -Dichlorobenzidine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 2,2'-dimethoxybenzidine, 4,4'-diaminodiphenyl sulfide, 3,3'- Diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 4,4′-oxydianiline, 3,3′-oxydianiline, 3,4′-oxydianiline, 1,5-diaminonaphthalene, 4,4 '-Diaminodiphenyldiethylsilane, 4,4'-diaminodiphenylsilane, 4,4'- Aminodiphenylethylphosphine 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-amino) Phenoxy) benzene, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone and the like.

  As the diamine component, a diamine having a rigid structure and an amine having a flexible structure can be used in combination, and the preferred use ratio in that case is 80/20 to 20/80, more preferably 70/30 to 30/70, in molar ratio. Particularly, it is 60/40 to 30/70. If the use ratio of the rigid diamine exceeds the above range, the tensile elongation of the resulting film tends to be small, and if it falls below this range, the glass transition temperature becomes too low or the storage modulus during heat decreases. In some cases, the film formation is difficult, and it may be harmful.

  In the present invention, the diamine having a rigid structure is

式中のＲ２は

R2 in the formula is

で表される２価の芳香族基からなる群から選択される基であり、式中のＲ₃は同一または異なってＨ−，ＣＨ₃−、−ＯＨ、−ＣＦ₃、−ＳＯ₄、−ＣＯＯＨ、−ＣＯ-ＮＨ₂、Ｃｌ−、Ｂｒ−、Ｆ−、及びＣＨ₃Ｏ−からなる群より選択される何れかの１つの基である）
で表されるものをいう。

And R _{3 in} the formula is the same or different and is H—, CH ₃ —, —OH, —CF ₃ , —SO ₄ , —, or a group selected from the group consisting of divalent aromatic groups. Any one group selected from the group consisting of COOH, —CO—NH ₂ , Cl—, Br—, F—, and CH ₃ O—)
The one represented by

  The diamine having a flexible structure is a diamine having a flexible structure such as an ether group, a sulfone group, a ketone group, or a sulfide group, and is preferably represented by the following general formula (2).

（式中のＲ₄は、

(R ₄ in the formula is

で表される２価の有機基からなる群から選択される基であり、式中のＲ₅は同一または異なって、Ｈ−，ＣＨ₃−、−ＯＨ、−ＣＦ₃、−ＳＯ₄、−ＣＯＯＨ、−ＣＯ-ＮＨ₂、Ｃｌ−、Ｂｒ−、Ｆ−、及びＣＨ₃Ｏ−からなる群より選択される１つの基である。）
本発明において用いられるポリイミドフィルムは、上記の範囲の中で所望の特性を有するフィルムとなるように適宜芳香族酸二無水物および芳香族ジアミンの種類、配合比を決定して用いることにより得ることができる。

R _{5 in} the formula is the same or different and is H—, CH ₃ —, —OH, —CF ₃ , —SO ₄ , —, or a group selected from the group consisting of divalent organic groups represented by One group selected from the group consisting of COOH, —CO—NH ₂ , Cl—, Br—, F—, and CH ₃ O—. )
The polyimide film used in the present invention is obtained by appropriately determining the type and blending ratio of the aromatic dianhydride and aromatic diamine so as to be a film having desired characteristics within the above range. Can do.

  As the preferred solvent for synthesizing the polyamic acid, any solvent can be used as long as it dissolves the polyamic acid. However, amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N- Examples thereof include methyl-2-pyrrolidone, and N, N-dimethylformamide and N, N-dimethylacetamide can be particularly preferably used.

  In addition, a filler can be added for the purpose of improving various film properties such as slidability, thermal conductivity, conductivity, corona resistance, and loop stiffness. Any filler may be used, but preferred examples include silica, titanium oxide, alumina, silicon nitride, boron nitride, calcium hydrogen phosphate, calcium phosphate, mica and the like.

The particle size of the filler is not particularly limited because it is determined by the film characteristics to be modified and the kind of filler to be added, but generally the average particle size is 0.05 to 100 μm, preferably 0.1. It is -75 micrometers, More preferably, it is 0.1-50 micrometers, Most preferably, it is 0.1-25 micrometers. 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. Further, the number of added parts of the filler is not particularly limited because it is determined by the film properties to be modified, the filler particle diameter, and the like. Generally, the addition amount of the filler is 0.01 to 100 parts by weight, preferably 0.01 to 90 parts by weight, and more preferably 0.02 to 80 parts by weight with respect to 100 parts by weight of the polyimide. 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. Addition of filler
1. 1. A method of adding to a polymerization reaction solution before or during polymerization 2. A method of kneading fillers using three rolls after the completion of polymerization. Any method such as preparing a dispersion containing filler and mixing it with a polyamic acid organic solvent solution may be used, but a method of mixing a dispersion containing filler with a polyamic acid solution, particularly immediately before film formation. This method is preferable because the contamination by the filler in the production line is minimized. When preparing a dispersion containing a filler, it is preferable to use the same solvent as the polymerization solvent for the polyamic acid. Further, in order to disperse the filler satisfactorily and stabilize the dispersion state, a dispersant, a thickener and the like can be used within a range not affecting the film physical properties.

  The solution containing the precursor of the non-thermoplastic polyimide resin thus obtained is also referred to as a solution containing a precursor of high heat resistant polyimide.

<Adhesive layer>
In the adhesive layer according to the present invention, the content, molecular structure, and thickness of the thermoplastic polyimide resin contained in the layer are not particularly limited as long as a significant adhesive force is expressed by a laminating method. However, in order to develop a significant adhesive force, it is preferable that the thermoplastic polyimide resin is substantially contained in an amount of 50 wt% or more.

  As the thermoplastic polyimide contained in the thermoplastic polyimide layer, thermoplastic polyimide, thermoplastic polyamideimide, thermoplastic polyetherimide, thermoplastic polyesterimide and the like can be suitably used. Among these, thermoplastic polyesterimide is particularly preferably used from the viewpoint of low moisture absorption characteristics.

  The thermoplastic polyimide contained in the thermoplastic polyimide layer according to the present invention is obtained by a conversion reaction from the precursor polyamic acid. As the method for producing the polyamic acid, any known method can be used as in the precursor of the high heat resistant polyimide layer.

  In view of the fact that lamination with an existing apparatus is possible and the heat resistance of the resulting metal-clad laminate is not impaired, the thermoplastic polyimide in the present invention has a glass transition temperature (150 to 300 ° C.). Tg) is preferred. 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).

  The polyamic acid that is a precursor of the thermoplastic polyimide used in the present invention is not particularly limited, and any known polyamic acid can be used. Regarding the production of the polyamic acid solution, the raw materials and the production conditions can be used in exactly the same manner.

  The properties of thermoplastic polyimide can be adjusted by combining various raw materials to be used, but generally the glass transition temperature becomes higher and / or the storage elastic modulus during heat when the ratio of rigid diamine is increased. Is unfavorable because it increases the adhesion and processability. The diamine ratio of the rigid structure is preferably 40 mol% or less, more preferably 30 mol% or less, and particularly preferably 20 mol% or less.

  Specific examples of preferable thermoplastic polyimide resins include those obtained by polymerization reaction of acid dianhydrides including biphenyltetracarboxylic dianhydrides and diamines having aminophenoxy groups.

  Furthermore, for the purpose of controlling the properties of the adhesive film according to the present invention, inorganic or organic fillers, and other resins may be added as necessary.

<Manufacture of adhesive film>
It is essential that the method for obtaining the adhesive film according to the present invention is a coextrusion-casting method. The coextrusion-casting method according to the present invention includes a solution containing a precursor of a high heat-resistant polyimide and a solution containing a thermoplastic polyimide or a solution containing a precursor of a thermoplastic polyimide in two or more layers. It is a method for producing a film including a step of simultaneously feeding to an extrusion molding machine having a multilayer die and extruding both solutions as at least two layers of thin-film bodies from the outlet of the multilayer die. To describe a commonly used method, both of the solutions extruded from two or more multilayer dies are continuously extruded onto a smooth support, and then the multilayer thin film on the support is formed. By volatilizing at least a part of the solvent, a multilayer film having self-supporting properties can be obtained. Further, the multilayer film is peeled off from the support, and finally, the multilayer film is sufficiently heated at a high temperature (250-600 ° C.) to substantially remove the solvent and advance imidization. Thereby, the target adhesive film is obtained. Further, for the purpose of improving the melt fluidity of the adhesive layer, the imidization rate may be intentionally lowered and / or the solvent may be left.

  The support according to the present invention casts a multilayer liquid film extruded from a multilayer die, and heat-drys the multilayer liquid film on the support to give self-supporting property. The shape of the support is not particularly limited, but in consideration of the productivity of the adhesive film, a drum shape or a belt shape is preferable. The material of the support is not particularly limited, and examples thereof include metals, plastics, glass, porcelain, etc., preferably metals, and more preferably SUS materials that do not rust and have excellent corrosion resistance. Further, metal plating such as Cr, Ni, Sn may be performed.

  In the present invention, it is important that the surface roughness Ra of the support is in the range of 0.002 to 1 μm. The surface roughness of the support according to the present invention refers to an average value of the surface roughness Ra measured at a total of 10 points at random locations based on JIS B-0601 “Surface roughness”. The surface roughness Ra can be measured with a cut-off value of 0.25 mm, for example, using a surface roughness meter Surf Test SJ-301 manufactured by Mitutoyo Corporation. The value Ra measured with a cut-off value of 0.25 mm refers to an arithmetic average roughness calculated from a roughness curve obtained by removing irregularities having a wavelength longer than 0.25 mm from measured data.

  In general, polyimide is obtained by a dehydration conversion reaction from a polyimide precursor, that is, a polyamic acid, and as a method for performing the conversion reaction, a thermal curing method that is performed only by heat and a chemical curing method that uses a chemical dehydrating agent. The two methods are most widely known. However, in the present invention, it is essential to employ a chemical curing method.

  Here, the chemical curing agent includes a dehydrating agent and a catalyst. The dehydrating agent here is a dehydrating ring-closing agent for polyamic acid, and as its main component, aliphatic acid anhydride, aromatic acid anhydride, N, N'-dialkylcarbodiimide, lower aliphatic halide, halogenated Lower aliphatic acid anhydrides, aryl sulfonic acid dihalides, thionyl halides or mixtures of two or more thereof can be preferably used. Of these, aliphatic acid anhydrides and aromatic acid anhydrides work particularly well. The catalyst is a component having an effect of accelerating the dehydration ring-closing action of the curing agent on the polyamic acid. For example, an aliphatic tertiary amine, an aromatic tertiary amine, or a heterocyclic tertiary amine can be used. . Of these, nitrogen-containing heterocyclic compounds such as imidazole, benzimidazole, isoquinoline, quinoline, or β-picoline are preferred. Furthermore, introduction of an organic polar solvent into a solution composed of a dehydrating agent and a catalyst can be appropriately selected.

  Although there is no particular limitation regarding the method of volatilization of the solvent in the precursor solution of the high heat-resistant polyimide extruded from the multilayer die of two or more layers and the solution containing the thermoplastic polyimide or the precursor of the thermoplastic polyimide, The method using heating and / or blowing is the simplest method. When the temperature at the time of heating is too high, the solvent is volatilized rapidly, and the trace of the volatilization causes a micro defect to be formed in the finally obtained adhesive film. Preferably there is.

  As for the imidization time, it suffices to take a sufficient time for the imidization and drying to be substantially completed, and although it is not uniquely limited, generally it is appropriately set within a range of about 1 to 600 seconds. Is done.

  The tension applied during imidization is preferably in the range of 1 kg / m to 15 kg / m, and particularly preferably in the range of 5 kg / m to 10 kg / m. If the tension is smaller than the above range, sagging or meandering may occur during film conveyance, which may cause problems such as wrinkling during winding or inability to uniformly wind. On the other hand, when it is larger than the above range, since it is heated at a high temperature in a state where a strong tension is applied, the dimensional characteristics of the obtained flexible metal-clad laminate may be deteriorated.

  As the above-mentioned multilayer die having two or more layers, those having various structures can be used. For example, a T die for forming a film for a plurality of layers can be used. In addition, any conventionally known structure can be suitably used, and feed block T dies and multi-manifold T dies are exemplified as particularly suitable ones.

Next, the manufacturing method of the adhesive film which concerns on this invention is demonstrated in detail by an Example.

(Synthesis Example 1; Synthesis of Polyamic Acid as Precursor of High Heat-Resistant Polyimide Compound)
239 kg of N, N-dimethylformamide (hereinafter also referred to as DMF) cooled to 10 ° C., 6.9 kg of 4,4′-oxydianiline (hereinafter also referred to as ODA), p-phenylenediamine (hereinafter also referred to as p-PDA) After dissolving 9.4 kg of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (hereinafter also referred to as BAPP) 6.2 kg, pyromellitic dianhydride (hereinafter also referred to as PMDA). ) 10.4 kg was added and dissolved by stirring for 1 hour. To this, 20.3 kg of benzophenone tetracarboxylic dianhydride (hereinafter also referred to as BTDA) was added and dissolved by stirring for 1 hour.

  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 3500 poise. Stirring was performed for 1 hour to obtain a polyamic acid solution of a precursor of a high heat resistant polyimide compound having a solid content concentration of 18% by weight and a rotational viscosity at 23 ° C. of 3500 poise.

Synthesis Example 2 Synthesis of Polyamic Acid as a Precursor of Thermoplastic Polyimide Compound
To a 300 L reaction vessel, 78 kg of DMF and 11.56 kg of 2,2-bis [4- (4-aminophenoxy) phenyl] propane (BAPP) were added, and while stirring under a nitrogen atmosphere, 3,3′4,4 7.87 kg of '-biphenyltetracarboxylic dianhydride (BPDA) was gradually added. Subsequently, 0.38 kg of ethylenebis (trimellitic acid monoester acid anhydride) (TMEG) was added and stirred for 30 minutes in an ice bath. A solution prepared by dissolving 0.2 kg of TMEG in 4 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 3300 poise, addition and stirring were stopped to obtain a polyamic acid solution as a precursor of a thermoplastic polyimide compound.

Example 1
The following chemical dehydrating agent and catalyst were contained in the polyamic acid solution of the precursor of the high heat-resistant polyimide obtained in Synthesis Example 1.
Chemical dehydrating agent: 2.0 mol per 1 mol of polyamic acid amic acid unit of acetic anhydride as precursor of high heat resistant polyimide Catalyst: 1 mol of amic acid unit of polyamic acid as precursor of high heat resistant polyimide Next, from a multi-manifold three-layer coextrusion multilayer die having a lip width of 650 mm, the outer layer is a polyamic acid solution of a precursor of the thermoplastic polyimide obtained in Synthesis Example 2, and the inner layer is highly heat resistant. The multilayer film formed in the order of the polyamic acid solution as the precursor of the polyimide solution was continuously extruded and cast onto a stainless steel endless belt running 20 mm below the T die. When the surface roughness Ra of the endless belt was measured at 10 points at random with a cut-off value of 0.25 mm using a surface roughness meter Surf Test SJ-301 manufactured by Mitutoyo Co., Ltd. based on JIS B-0601 “surface roughness” The average value was 0.008 μm. Next, the multilayer film was heated at 130 ° C. for 100 seconds to be converted into a self-supporting gel film. No delamination was observed on the gel film, and the gel film had a good appearance. Also, the self-supporting gel film was easily peeled off from the endless belt. Furthermore, it is fixed to a self-supporting gel film tenter clip peeled off from the endless belt, dried and imidized at 300 ° C. × 16 seconds, 400 ° C. × 29 seconds, 450 ° C. × 17 seconds, and each thermoplastic polyimide layer An adhesive film having a good shape of 3 μm and a high heat-resistant polyimide layer 18 μm was obtained.
Using 18 μm rolled copper foil (BHY-22B-T, manufactured by Japan Energy Co., Ltd.) on both sides of the obtained adhesive film, and further using a protective material (Apical 125 NPI; manufactured by Kaneka Chemical Co., Ltd.) on both sides of the copper foil, A flexible metal-clad laminate is obtained by continuously laminating a polyimide film with a tension of 0.4 N / cm, a laminating temperature of 380 ° C., a laminating pressure of 196 N / cm (20 kgf / cm), and a laminating speed of 1.5 m / min. When fabricated and the surface thereof was observed with a microscope, the metal foil was not observed to be slightly lifted or swollen.

(Reference Example 1)
An adhesive film and a flexible metal-clad laminate were prepared in the same manner as in Example 1 except that an endless belt having a surface roughness Ra of 1.1 μm was used.
No delamination was observed in the gel film, and the self-supporting gel film was easily peeled off from the endless belt.
However, when the surface of the obtained flexible metal-clad laminate was observed with a microscope, minute floats were observed at a ratio of several pieces to 250 mm × 250 mm.

(Reference Example 2)
An adhesive film was prepared in the same manner as in Example 1, except that the addition amount of isoquinoline as a catalyst was 2.1 mol with respect to 1 mol of the polyamic acid amic acid unit of the precursor of the high heat-resistant polyimide. .
Delamination occurred in the gel film, and the self-supporting gel film could not be peeled from the endless belt.

Claims (4)

A method for producing a multilayer film having at least two kinds of polyimide layers, wherein at least two kinds of solutions selected from a solution containing a polyimide resin precursor and a solution containing a polyimide resin are coextruded on a support. Including a step of casting to form two or more layers, wherein at least one of the solutions used in the coextrusion contains a chemical dehydrating agent and a catalyst, and is included in a solution containing the chemical dehydrating agent and the catalyst. 0.5 to 4.0 moles of chemical dehydrating agent and 0.05 to 2.0 moles of catalyst are used per mole of amic acid unit in the polyamic acid, and the support has a surface roughness Ra. Is in the range of 0.002 to 1 μm. The surface roughness Ra of the said support body is 0.002-0.1 micrometer, The manufacturing method of the adhesive film of Claim 1 characterized by the above-mentioned. The multilayer film is an adhesive film in which an adhesive layer containing a thermoplastic polyimide is laminated on at least one surface of a high heat resistant polyimide layer, and the solution used for the coextrusion includes a solution containing a precursor of a high heat resistant polyimide; The method for producing a multilayer film according to claim 1 or 2, which is a solution containing a precursor of thermoplastic polyimide and / or a solution containing thermoplastic polyimide. Use 1.0 to 3.0 mol of chemical dehydrating agent and 0.05 to 1.0 mol of catalyst for 1 mol of amic acid unit in polyamic acid contained in the solution containing the chemical dehydrating agent and catalyst. The manufacturing method of the multilayer film of Claim 1 thru | or 3 characterized by these.