JP6519126B2 - Transfer film, method for producing polyimide laminate using the same, and polyimide laminate - Google Patents

Description

  The present invention relates to a transfer film capable of transferring a polyimide precursor to a substrate made of glass or metal, a method for producing a polyimide laminate using the same, and a polyimide laminate produced using the same. More specifically, the present invention relates to a transfer film used for producing a polyimide laminate suitable as a substrate of an electronic device (electronic component), a method for producing a polyimide laminate, and a polyimide laminate produced using the same.

  In recent years, thickness reduction and weight reduction of electronic devices (electronic components) such as organic EL panels, solar cells, thin film secondary batteries and the like have progressed, and thinning of substrates used for these electronic devices has progressed. However, when glass is used for the substrate, there is a problem that when the strength of the glass substrate is reduced due to thinning, the handling property is deteriorated. In addition, although it is possible to use a resin substrate instead of a glass substrate, the resin substrate has problems in chemical resistance, moisture permeation resistance, heat resistance and the like as compared with a glass substrate. Moreover, the further heat resistance is calculated | required also by the resin / metal laminated body which laminated | stacked resin on the metal substrate.

Recently, for use in electronic devices such as organic EL panels, development of materials combining the characteristics of glass and the characteristics of plastic has been conducted.
For example, in order to obtain a transparent substrate excellent in flexibility, flexibility, impact resistance and appearance, an applied layer comprising a thermoplastic resin containing a solvent formed on a support substrate having solvent permeability and inorganic glass The laminate obtained by laminating the adhesive composition is subjected to a heat treatment to reduce the amount of residual solvent in the coating layer to a predetermined amount, and thereafter the support substrate is peeled off from the laminate, A method has been proposed in which the thermoplastic resin layer is formed on an inorganic glass by heat treatment again to dry the applied layer (Patent Document 1).

In addition, polyimide is generally known as a resin having high heat resistance. Patent Document 2 proposes a glass / resin laminate in which a resin layer containing a specific polyimide and a glass substrate are laminated. In Patent Document 2, as a method of laminating a resin layer and glass, a polyamic acid solution is coated on a polyethylene terephthalate (PET) film, heat-treated to prepare a heat-resistant polyimide film, and subjected to plasma treatment, The method of pressure-bonding the polyimide film after the said plasma processing using a metal roller on the ring-processed glass substrate is disclosed. There is also disclosed a method of setting a thermoplastic film between a glass substrate and a heat resistant polyimide film and heating and pressing to obtain a glass / resin laminate. Moreover, the method of apply | coating a polyamic-acid solution on the glass substrate after a silane coupling process, and performing heat processing as a method of forming a resin layer directly on a glass substrate is disclosed.
Also, a transfer sheet has been proposed in which a resin layer containing a polyamic acid, which is a precursor of polyimide, is formed on a release material. For example, a transfer sheet has been developed in which a photosensitive layer made of a photosensitive polyamic acid resin is formed on a release material, and an adhesive layer made of an adhesive polyamic acid resin is formed thereon (Patent Document 3). There is also proposed a method for producing a resin transfer material in which a resin layer containing a photosensitive polyamic acid is formed on a release material made of polyester (Patent Document 4). The resin transfer materials disclosed in Patent Documents 3 and 4 are thermally transferred onto a glass plate and then patterned to form a transfer sheet used for forming an insulating layer of a circuit board such as an electronic component or an adhesive layer of various electronic components. It is.
In Patent Document 5, a polyimide precursor solution comprising a specific constituent component is directly applied on a metal foil and cured, and a substrate for printed wiring on which a polyimide layer containing a porous polyimide layer and a metal foil layer are laminated. A method of manufacture is disclosed.

International Publication No. 2011/136327 brochure International Publication No. 2011/030716 Brochure Japanese Patent Laid-Open No. 2000-267276 JP 2005-301072 A JP 2012-101438 A

As substrates for electronic devices such as organic EL panels, further thickness reduction, high heat resistance, and handling properties are required. In order to produce a polyimide laminate in which polyimide and a substrate are laminated, which has such properties, in the method of directly heat-sealing the polyimide and the substrate, it is usually at least the glass transition temperature (Tg) of polyimide. Since it is necessary to heat, it is difficult to thermally fuse the polyimide which exhibits high heat resistance without glass transition temperature. Further, in the method of directly laminating the polyimide and the substrate, it is usually necessary to subject the substrate and the polyimide to a surface treatment in order to secure interlayer adhesion, and the manufacturing process becomes complicated. When a laminate of a thin polyimide and a base material such as glass with a thickness of several μm is produced by heat fusion, there is a method of transferring polyimide supported on a transfer base material such as PET onto glass. However, if it is intended to directly transfer polyimide onto glass without an adhesive layer, it is necessary to heat the polyimide to a temperature higher than the glass transition temperature, so the transfer substrate is required to have heat resistance higher than that of polyimide. Therefore, it is difficult to use a general-purpose transfer substrate such as PET, which is inferior in heat resistance to polyimide, and it is necessary to use an expensive heat-resistant transfer substrate. Also, depending on the polyimide, it is difficult to laminate due to its hardness.
Moreover, in the method of applying the polyimide precursor solution directly to the substrate surface, a long drying line is to be passed through for solvent drying, and when using a thinned glass substrate, the glass substrate is broken on the line Have a concern.
Therefore, a main object of the present invention is a transfer film which can be laminated at a low temperature and which can provide a polyimide laminate having high heat resistance and handling property which can be suitably used as a substrate for an electronic device such as an organic EL panel after transfer. It is providing the manufacturing method of a polyimide laminated body using the same, and a polyimide laminated body.

As a result of intensive investigations in view of the above problems, the present inventors formed a polyimide precursor layer having a specific imidation ratio on a substrate film to form a transfer film. Or it discovered that the polyimide laminated body which can be easily transferred on the base material which consists of metals, showed the outstanding heat resistance, and was excellent in the handling property was obtained, and came to complete this invention.
That is, the present invention is as follows.

[1] A transfer film comprising a base film and a polyimide precursor layer having an imidation ratio of 45% or less formed on the base film.
[2] The transfer film according to [1], wherein the thickness of the polyimide precursor layer is 1 μm to 50 μm.
[3] The transfer film according to [1] or [2], wherein the polyimide obtained by firing the polyimide precursor has a glass transition temperature of 200 ° C. or higher or no glass transition temperature.
[4] A roll-shaped product obtained by winding the transfer film according to any one of [1] to [3].
[5] The transfer film according to any one of [1] to [4] is laminated on at least one surface of a substrate made of glass or metal so that the polyimide precursor layer faces the substrate side,
Transfer step to transfer,
A method for producing a polyimide laminate, comprising: a peeling step of peeling the base film from the laminate obtained in the step; and a firing step of firing the polyimide precursor layer.
[6] The transfer temperature in the transfer step is a temperature lower than the glass transition temperature of the polyimide when the polyimide obtained by firing the polyimide precursor has a glass transition temperature, or obtained by firing the polyimide precursor The method for producing a polyimide laminate according to [5], wherein the temperature of the obtained polyimide is 200 ° C. or less when it does not have a glass transition temperature.
The polyimide laminated body obtained by the manufacturing method as described in [7] [5] or [6].
[8] A roll-like product obtained by winding the polyimide laminate according to [7].

  According to the present invention, it is possible to provide a polyimide laminate having high heat resistance and handling properties that can be suitably used as a substrate for an electronic device such as an organic EL panel after transfer, a low-temperature laminateable transfer film, It is possible to provide a method for producing a polyimide laminate, and to obtain a polyimide laminate having high heat resistance and handling properties.

  The embodiment of the transfer film and the polyimide laminate of the present invention will be described in detail below, but the description of the constituent requirements described below is an example (representative example) of the embodiment of the present invention, and the present invention It is not specified in these contents.

  Hereinafter, a transfer film of the present invention (hereinafter, also referred to as “the present transfer film”), a method of producing a polyimide laminate (hereinafter, also referred to as the “present polyimide laminate”) produced using the present transfer film, and the present polyimide laminate The bodies and the materials that make them up will be described in detail.

<Transfer film>
The transfer film of the present invention is a transfer film having a structure in which a polyimide precursor layer having an imidization rate of 45% or less is provided on a base film. Hereinafter, the base film which comprises a transfer film, and a polyimide precursor layer are demonstrated.

<Base film>
A base film is a support body which supports a polyimide precursor layer in a transfer film, and is a release film which exfoliates from a layered product, after making a transfer film laminate on other members and transferring a resin layer.
It does not specifically limit as a material which comprises a base film, Although a well-known thing can be used arbitrarily, It is preferable to have heat resistance. That is, a polyimide precursor solution containing a polyimide precursor dissolved in a solvent can be applied to the surface, the solvent can be dried, and the transfer film can be thermally laminated on a substrate made of glass or metal It is preferable to have heat resistance to some extent.
Specifically as a material which comprises such a base film, polyester-type resin, polyolefin-type resin, polycarbonate-type resin, etc. are mentioned. Among these resins, polyester resins are preferable from the viewpoint of heat resistance and coatability.

As polyester resin which can be used for a substrate film, copolymers of various polyvalent carboxylic acids and various polyvalent alcohols, homopolymers of various hydroxycarboxylic acids, polyvalent carboxylic acids, polyvalent alcohols and hydroxycarboxylic acids Preferred are copolymers and the like.
Among them, copolymers having mainly terephthalic acid and ethylene glycol (so-called polyethylene terephthalate), and copolymers having mainly naphthalene dicarboxylic acid and ethylene glycol (from the viewpoint of high transparency and appropriate elongation and strength) So-called polyethylene naphthalates) are particularly preferred. In these copolymers, for example, a third component such as isophthalic acid may be copolymerized.

The thickness of the substrate film is preferably 20 μm or more, more preferably 30 μm or more, and 38 μm or more from the viewpoint of improving the handling property of the transfer film and the removability after transfer. Is particularly preferred. The thickness is preferably 150 μm or less, more preferably 130 μm or less, and particularly preferably 100 μm or less.
If the thickness of the substrate film is 20 μm or more, the handling properties of the present transfer film can be improved, but if the thickness of the substrate film is 150 μm or less, the bending elasticity of the substrate film does not become too large. After laminating this transfer film on the base material which consists of glass or a metal, the peelability at the time of peeling a base film becomes favorable.

In the present invention, when the polyimide precursor layer of the transfer film is transferred to the substrate to form a polyimide laminate, the surface of the polyimide precursor layer on the substrate film side is the surface opposite to the substrate side. For this reason, it is preferable that the average surface roughness (arithmetic average roughness (Sa)) of the substrate film surface is small, from the viewpoint of enhancing the smoothness of the polyimide precursor layer surface and further the polyimide side surface of the present polyimide laminate. Specifically, it is preferably 100 nm or less, more preferably 10 nm or less, and particularly preferably 2 nm or less. The lower limit is not particularly limited, but is about 0.001 nm.
The average surface roughness is arithmetic average roughness (Sa), and can be calculated by the following measurement method.
(Method of measuring arithmetic mean roughness (Sa))
The surface observation (observation visual field: 93.97 μm × 71.30 μm) of the base film is carried out using the non-contact surface / layer cross-section measurement system VertScan 2.0 (manufactured by Ryoka System Co., Ltd.), and the surface of the base film is The average surface roughness (arithmetic average roughness Sa) is calculated.
As a method of adjusting the average surface roughness of the resin layer side surface of the base film, the average surface roughness may be prepared in the above range, and the average surface roughness may be adjusted by a known method. You may purchase the commercial item of the range concerned.
On the other hand, in the transfer film, it is necessary to laminate the transfer film with another member and transfer the resin layer to the other member and then to peel off the base film, so the surface on the resin layer side of the base film is good. Releasability is required. Therefore, in order to improve releasability, surface treatment with a release agent such as silicone resin is usually performed. The surface treatment with such a mold release agent tends to increase the average surface roughness of the surface.

In the present invention, a polyimide precursor solution of the substrate film as needed within a range that does not impair the smoothness of the substrate film surface, the coatability of the polyimide precursor solution, the releasability with the polyimide precursor layer, etc. Surface treatment may be applied to the surface on the side of application.
Specifically, for example, surface treatment may be performed by corona treatment, low-pressure plasma treatment, atmospheric pressure plasma treatment, flame treatment, and ultraviolet radiation treatment for the purpose of improving the coating property of the polyimide precursor solution, or smooth. You may perform the chemical treatment. In addition, a resin layer may be provided using a heat- or light-curable resin or a thermoplastic resin for the purpose of improving the coatability and smoothing the surface. Moreover, you may process by an anchor-coat agent for the purpose of the adhesive improvement.
On the other hand, from the viewpoint of the coatability of the polyimide precursor solution, it is preferable to use a base film which has not been treated with a release agent such as silicone, long chain alkyl or fluorine based surface of the polyimide precursor solution. preferable. Since the base film of the transfer film is one that peels off after transfer, usually, one having excellent releasability is suitably used. On the other hand, the base film surface treated with the mold release agent as described above easily repels the polyimide precursor solution.
In the present invention, when it is intended to apply a polyimide precursor solution to a substrate film treated with such a release agent, it is necessary to increase the solid concentration of the polyimide precursor solution in order to improve the coatability. However, if the solid content concentration is increased, for example, air bubbles may be entrapped during application to cause coating unevenness, which may result in appearance defects in the polyimide precursor layer. Get higher.
In addition, as described above, the surface treatment with the release agent tends to increase the average surface roughness of the surface, so the surface of the polyimide layer may be roughened when it is formed into a polyimide laminate. . For these reasons, in the present invention, it is preferable to use a base film which has not been treated with a releasing agent such as silicone, long chain alkyl or fluorine based surface on the application side surface of the polyimide precursor solution. Using a base film which has not been treated with a release agent is also advantageous in cost.

<Polyimide precursor layer>
The polyimide precursor layer having an imidization ratio of 45% or less in the present transfer film is obtained by applying a polyimide precursor solution in which a polyimide precursor is dissolved in a solvent on a substrate film and drying the solvent by heat treatment. It is formed. That is, the polyimide precursor layer of the present invention contains a polyimide precursor having an imidization ratio of 45% or less, and also contains a solvent and the like in addition to the polyimide precursor. Since the polyimide precursor layer in the present transfer film has an imidization ratio of 45% or less, an adhesive layer is used on a substrate made of glass or metal at a temperature not higher than the glass transition temperature (Tg) of the polyimide. Even without it, it can be easily transferred. In addition, since the transfer film provided with the polyimide precursor layer has flexibility, and the surface of the polyimide precursor layer does not generally have tackiness that causes blocking, it also blocks as a roll-like product formed in a roll. It is difficult and can be used and stored in the form of a roll.
Furthermore, the polyimide precursor layer in the present transfer film is used by using a substrate film having a small average surface roughness, or applying a polyimide precursor solution to a uniform thickness on the substrate to suppress coating unevenness. Appearance defects can be reduced. By transferring such a transfer film to a substrate made of glass or metal, it is possible to obtain a polyimide laminate having few defects in appearance and excellent in smoothness.

In the polyimide precursor layer of the transfer film, the upper limit of the imidation ratio is 45%. In the present invention, by setting the imidization ratio to 45% or less, the elastic modulus of the polyimide precursor layer at the temperature at the time of transfer described later can be set as a preferable range for transfer. The polyimide precursor layer can be well transferred onto a substrate made of glass or metal. That is, by setting the imidization ratio of the polyimide precursor layer to 45% or less, the elastic modulus at the transfer temperature of the polyimide precursor layer can be set to 1 GPa or less, and to the substrate made of glass or metal, adhesion layer It can be easily transferred without interposing. Since transfer can be performed without using an adhesive layer, it is not necessary to use an adhesive layer having high heat resistance, the process of providing an adhesive layer is unnecessary, the number of manufacturing processes can be reduced, and manufacturing becomes possible in a short time. Also, it is possible to reduce the cost.
In the present invention, the elastic modulus refers to a value measured by the following method. The elastic modulus is a vibration frequency of 10 Hz, strain 0.1%, heating rate 3 ° C./min. Storage elastic modulus (E ') at transfer temperature when measured in the longitudinal direction of the sheet under the following conditions.
In addition, from the viewpoint of thermal lamination characteristics, the imidation ratio of the polyimide precursor layer is preferably 43% or less, and more preferably 40% or less. In addition, from the viewpoint of the balance between the thermal lamination characteristics and the residual solvent, the imidation ratio of the polyimide precursor layer is preferably 3% or more, more preferably 5% or more, more preferably 7% or more, and particularly preferably 10% or more.

The amount of residual solvent in the polyimide precursor layer of the transfer film is preferably 30 wt% or less, more preferably 15 wt% or less, and more preferably 10 wt% or less based on the total weight of the polyimide precursor layer. Particularly preferred. The amount of residual solvent in the polyimide precursor layer is 30
If it is wt% or less, the adhesion of the surface of the polyimide precursor layer is lost, so that the transfer film can be wound into a roll without providing a protective layer on the polyimide precursor layer. In addition, the measuring method of the amount of residual solvents in the polyimide precursor layer of this transfer film is not specifically limited. For example, a method of performing heat treatment at a constant temperature for a constant time and obtaining from the difference in weight before and after heat treatment, a method of volatilizing a residual solvent with a gas chromatograph mass spectrometer, and the like can be mentioned.

The thickness of the polyimide precursor layer of the present invention is preferably 1 μm or more and 50 μm or less. Within this range, good thermal transfer can be performed on a substrate made of glass or metal. Moreover, from a viewpoint of preventing the baking nonuniformity at the time of heat processing (baking) of a polyimide precursor layer, 50 micrometers or less are preferable, 30 micrometers or less are more preferable, 25 micrometers or less are more preferable, and 20 micrometers or less are especially preferable. Thus, when the thickness of the polyimide precursor layer is 1 μm or more and 50 μm or less, for example, the occurrence of baking unevenness caused by the release of moisture and residual solvent from the polyimide precursor layer is suppressed during heat treatment (baking) Thus, it is possible to obtain a polyimide laminate having a polyimide layer of uniform thickness. In general, a transfer film requires a certain thickness in preparation for breakage due to stress during transfer. In the present embodiment, by setting the imidation ratio of the polyimide precursor layer to 45% or less, even if the film thickness of the polyimide precursor layer is made thin as described above, a substrate made of glass or metal having a small thickness Can be suitably transferred. Further, by reducing the thickness of the polyimide precursor layer, it is possible to form a dense polyimide having a uniform thickness after firing, and to obtain a polyimide laminate having high heat resistance and excellent handling. By using the polyimide laminate having a uniform and thin thickness as described above, the thickness and weight of the electronic device can be reduced.
In addition, baking intends the heat processing for advancing the dehydration and cyclization (imidization) reaction of a polyimide precursor.
In addition, the state in which uneven firing occurs is intended to be a state in which dark and light portions are generated on the surface of the fired polyimide due to the difference in the thickness of the polyimide, that is, uneven. doing.

(Polyimide precursor)
As a polyimide precursor of the polyimide precursor layer of this invention, a polyamic acid is mentioned. As a polyamic acid, when a polyimide precursor layer is formed on a general-purpose substrate film, it is particularly limited as long as it can be thermally transferred onto a substrate made of glass or metal at a temperature not higher than the temperature at which the substrate film melts. It is not a thing.

(Polyamic acid)
The polyamic acid which is a polyimide precursor of the present invention can be obtained by the reaction of a diamine and a tetracarboxylic acid dianhydride.

As the diamine, for example, p-phenylenediamine, m-phenylenediamine, 3,4'-diaminodiphenylether, 4,4'-diaminodiphenylether, 4,4'-diaminodiphenylmethane, 3,3'-dimethyl-4,4 '-Diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 1,2-bis (anilino) ethane, diaminodiphenylsulfone, diaminobenzanilide, diaminobenzoate, diaminodiphenyl sulfide, 2-Bis (p-aminophenyl) propane, 2,2-bis (p-aminophenyl) hexafluoropropane, 1,5-diaminonaphthalene, diaminotoluene, diaminobenzotrifluoride, 1,4-bis (p-amino Phenoxy) benzene, 4,4'-bis (p-aminophenoxy) biphenyl, diaminoanthraquinone, 4,4'-bis (3-aminophenoxyphenyl) diphenyl sulfone, 1,3-bis (anilino) hexafluoropropane, 1,4-bis ( Anilino) octafluorobutane, 1,5-bis (anilino) decafluoropentane, and 1,7-bis (anilino) tetradecafluoroheptane. As a diamine, you may use individually and may use together 2 or more types as a mixture.
Among these, p-phenylenediamine, m-phenyldiamine, 3,4'-diaminodiphenyl ether, and 4,4'-diaminodiphenyl ether are preferably used from the viewpoint of obtaining a highly heat-resistant polyimide laminate.

  Examples of tetracarboxylic acid dianhydride include pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, 3,3 ′, 4,4'-Diphenylsulfonetetracarboxylic acid, 3,3 ', 4,4'-diphenylethertetracarboxylic acid, 2,3,3', 4'-benzophenonetetracarboxylic acid, 2,3,6,7-naphthalene Tetracarboxylic acid, 1,4,5,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 3,3 ', 4,4'-diphenylmethane tetracarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) propane, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane, 3,4,9,10-tetracarboxype Dianhydrides such as lene, 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] propane, and 2,2-bis [4- (3,4-dicarboxyphenoxy) phenyl] hexafluoropropane The thing is mentioned. The tetracarboxylic dianhydrides may be used alone or in combination of two or more. Among these, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4 ′ from the viewpoint of obtaining a highly heat-resistant polyimide laminate. Preference is given to using diphenyl sulfone tetracarboxylic acid dianhydride.

  The polyamic acid is usually dissolved in a solvent and used as a polyamic acid solution. The total solid concentration in the polyamic acid solution including the polyamic acid and the other components is preferably 5% by weight or more from the viewpoint of the coating property and the appearance of the polyimide precursor layer after solvent drying, More preferably, it is at least 10% by weight, and more preferably at least 10% by weight. The content is preferably 30% by weight or less, more preferably 25% by weight or less, and particularly preferably 20% by weight or less. If the said solid content concentration is 5 weight% or more and 30 weight% or less, since generation | occurrence | production of the coating nonuniformity and the defect on the external appearance of a polyimide precursor layer can be suppressed, it is preferable.

As solvents for the polyamic acid solution, amide solvents such as N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide, diethyl sulfoxide and the like And sulfones such as dimethylsulfone and diethylsulfone. These solvents may be used alone or in combination.
The polyamic acid solution can be prepared by reacting tetracarboxylic acid dianhydride and diamine in a substantially equimolar amount or a slight excess of either component in an organic solvent. Moreover, what is marketed can also be used as it is, and what is marketed can also be prepared and used. Also, polyamic acid solutions having different imidation ratios may be mixed and used.
As a polyamic acid solution marketed, a unitika "U imide varnish AR", "U imide varnish BH", "U imide varnish CR", Ube Industries "U- varnish" etc. can be used suitably, for example.

  In addition, additives such as a silane coupling agent may be added to the polyamic acid solution in order to enhance the adhesion to a substrate made of glass or metal, as long as the object of the present invention is not impaired.

Examples of the silane coupling agent include 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-isocyanate propyl triethoxysilane, 3-glycidoxy propyl trimethoxysilane, etc. are mentioned.

  In addition, an imidization catalyst and a dehydrating agent may be added as long as the object of the present invention is not impaired, and a filler, a flame retardant, a flame retardant auxiliary and the like may be added.

If necessary, surface treatment is applied to the surface of the polyimide precursor layer as long as it does not impair the adhesion with the substrate surface made of glass or metal and physical properties such as heat resistance of the polyimide laminate. It is also good.
Specifically, for example, a silane coupling treatment using a silane coupling agent, a corona treatment, a low pressure plasma treatment, an atmospheric pressure plasma treatment, and a flame for the purpose of improving adhesion with a substrate surface made of glass or metal. Surface treatment may be performed by treatment and ultraviolet irradiation treatment, or smoothing treatment may be performed.

<Adhesive layer>
The transfer film of this embodiment can be suitably thermally transferred to a substrate made of glass or metal without using an adhesive layer by using a polyimide precursor layer having a specific imidation ratio, but an adhesive It may further have a layer. When it has an adhesive layer, it laminates | stacks in order of a base film, a resin layer, and an adhesive layer. By having an adhesive layer, the adhesiveness of the member which transcribes | transfers a transfer film, and a resin layer can be improved.
From the viewpoint of the heat resistance of the present polyimide laminate, the adhesive layer is not limited to an adhesive layer inferior in heat resistance to polyimide, and examples thereof include an epoxy resin, an acrylic resin, and a silicone resin.
The thickness of the adhesive layer is not particularly limited, and is usually 300 nm or more, preferably 500 nm or more, and usually 2 μm or less, preferably 1 μm or less.
The method for forming the adhesive layer is not particularly limited, and methods such as the coating described above can be used.

<Protective layer>
The transfer film of the present embodiment may further have a protective layer. When it has a protective layer, it laminates in order of a substrate film, a polyimide precursor layer, (adhesive layer), and a protective layer. By having a protective layer, the surface of the polyimide precursor layer can be prevented from being contaminated or damaged, and the transfer film can be well stored. Moreover, when it has an adhesive bond layer, by providing a protective layer, it can be set as a roll-like thing irrespective of the adhesiveness of an adhesive bond layer. The protective layer is used by peeling it from the transfer film before using the transfer film.
The protective layer is not particularly limited as long as it can be peeled without impairing the form of the polyimide precursor layer or the adhesive layer, but polyethylene films, polypropylene films, polymethylpentene films, polyester films, etc. A release paper coated on one side or both sides of the material may, for example, be mentioned.

<Method of producing transfer film>
The transfer film can be produced by applying a solution of polyamic acid which is a polyimide precursor on the surface of a substrate film and drying it.

  As a method of applying the polyamic acid solution on the surface of the substrate film, any conventional method can be used as long as it can be applied to a target thickness. For example, die coating, bar coater coating, mayer bar coating, air knife coating, gravure coating, reverse gravure coating, offset printing, flexographic printing, screen printing, dip coating can be mentioned.

  The heat treatment method for drying the solvent of the applied polyamic acid solution is not particularly limited as long as it can maintain the necessary temperature and time. For example, a method of storing in an oven or a constant temperature room set at a predetermined temperature, a method of blowing hot air, a method of heating with an infrared heater, a method of irradiating light with a lamp, a heat roll or a heat plate to make contact directly And the method of irradiating a microwave etc. can be used. Moreover, after heat-processing after cutting a base film to the magnitude | size which is easy to handle, you may heat-process in the state of a base film roll. Furthermore, a heating device can be incorporated into a part of a coating apparatus such as a coater, and heat treatment can be performed in the coating process.

The heat treatment conditions for drying the solvent of the applied polyamic acid solution are not particularly limited as long as the solvent can be dried and the imidation ratio of the polyimide precursor layer can be made within the above range.
Although the drying conditions depend on the polyimide precursor to be used and the intended thickness, it is usually 50 ° C. or more, preferably 60 ° C. or more, more preferably 70 ° C. or more, more preferably 75 ° C. or more from the viewpoint of imidization reaction rate. C. or higher, particularly preferably 80.degree. C. or higher. Also, from the viewpoint of the heat resistance of the base film, the temperature is usually 200 ° C. or less, preferably 180 ° C. or less, more preferably 170 ° C. or less, still more preferably 160 ° C. or less, particularly preferably 150 ° C. or less.
The drying time is usually 1 minute or more, preferably 3 minutes or more, from the viewpoint of productivity. Also, from the viewpoint of controlling the degree of crystallinity, it is carried out in 30 minutes or less, preferably 20 minutes or less, more preferably 10 minutes or less. In this embodiment, since the thin polyimide precursor layer is heat-treated, the imidation ratio of the polyimide precursor layer can be set as a target range in a short time as described above.
Moreover, you may dry at fixed temperature, and the temperature which was preheated from 10 degreeC / min. The temperature may be raised to an extent and dried. It is preferable to raise the drying temperature sequentially from the viewpoint of preventing the drying unevenness at the time of drying.
The drying may be performed in an inert gas atmosphere such as nitrogen, argon, helium or the like, or in an active gas atmosphere such as air, or in a vacuum state.
By performing such heat treatment, the solvent can be dried, and the imidation ratio of the polyimide precursor layer can be adjusted within the range described above.
Moreover, after forming the polyimide precursor layer on glass or a polyester film, the formed polyimide precursor layer can be transferred on a base film, and the transfer film of this invention can also be manufactured.

  In order to make the transfer film thus produced into a roll, a known winding device can be used. In addition, it is possible to design the device which incorporates the winding device so as to take up continuously after the drying process.

<Polyimide laminate>
Another embodiment of the present invention is a polyimide laminate in which a polyimide layer is laminated on at least one surface of a substrate made of glass or metal. The present polyimide laminate is thermally laminated so that the surface on the polyimide precursor layer side of the transfer film faces the substrate made of glass or metal, the substrate film is peeled off, and the polyimide precursor layer is formed on the substrate surface. After transfer, the polyimide precursor layer is fired at a suitable temperature and imidized to obtain a polyimide layer. The polyimide laminate may have a polyimide layer on one side of the substrate, or may have on both sides.

<Substrate made of glass or metal>
The glass substrate that can be used in the present embodiment is not particularly limited. Specifically, soda lime glass, borosilicate glass, non-alkali glass and the like can be exemplified. As such glass, what is marketed can be used.

  The thickness of the glass substrate is preferably 10 μm or more, more preferably 15 μm or more, and particularly preferably 20 μm or more from the viewpoint of using as a material of an electronic device. The thickness is preferably 200 μm or less, more preferably 150 μm or less, and particularly preferably 100 μm or less. In the present invention, as long as it is a glass substrate having a thickness in the above range, by having a polyimide layer on one side or both sides, the handling property is excellent and it can be wound as a roll.

  For the purpose of improving the adhesion to the polyimide precursor layer and / or the polyimide layer, the glass substrate may be treated with a coupling agent such as a silane coupling agent or a titanium coupling agent, acid treatment, alkali treatment, ozone treatment, Chemical treatment such as ion treatment, plasma treatment, glow discharge treatment, arc discharge treatment, discharge treatment such as corona treatment, ultraviolet light treatment, X-ray treatment, gamma ray treatment, electromagnetic wave irradiation treatment such as laser treatment, surface treatment such as flame treatment Various surface treatments, such as, may be performed.

  Specific examples of the metal substrate include hot rolled steel plate, cold rolled steel plate, galvanized steel plate, electrogalvanized steel plate, nickel plated steel plate, tin plate, tin free steel plate, brass plate, copper plate, copper plate, aluminum plate, aluminum alloy plate And stainless steel plates. As such a metal substrate, those commercially available can be used.

  The thickness of the metal substrate is preferably 10 μm or more, more preferably 15 μm or more, and particularly preferably 20 μm or more. The thickness is preferably 200 μm or less, more preferably 150 μm or less, and particularly preferably 100 μm or less. In the present invention, if it is a metal base of 10 μm or more and 200 μm or less, it can be wound as a roll, and can be used as a substrate material of a flexible electronic circuit.

  These metal plates may have their surfaces chemically treated. Examples of chemical treatments include plating, immersion chromic acid treatment, phosphoric acid chromic acid treatment, zinc chromate treatment, alumite treatment, primer coating treatment, and the like.

<Polyimide layer>
In the present embodiment, the polyimide layer of the polyimide laminate is formed by subjecting the polyimide precursor layer transferred from the present transfer film to a baking treatment on the surface of a substrate made of glass or metal. From the viewpoint of the heat resistance of the polyimide laminate, the polyimide layer is preferably a polyimide having a glass transition temperature of 200 ° C. or higher, or a polyimide having no glass transition temperature. The glass transition temperature is more preferably 300 ° C. or more, particularly preferably 350 ° C. or more. If the heat resistance temperature of the polyimide layer is 200 ° C. or more, it is preferable because the present polyimide laminate can be used as a substrate of an electronic device. Although the upper limit of the glass transition temperature is not limited, it is usually 600 ° C. or less.
In the present invention, the glass transition temperature is a value measured by the following method.
(Method of measuring glass transition temperature)
The glass transition temperature is a vibration frequency of 10 Hz, a strain of 0.1%, a heating rate of 3 ° C./min. The peak temperature of loss elastic modulus (E ′ ′) is measured when measured in the longitudinal direction of the sheet under the following conditions. If there are multiple peak temperatures of loss elastic modulus (E ′ ′), the highest temperature is Let it be the glass transition temperature. Moreover, when not showing a peak, it shall not have a glass transition temperature.

The average surface roughness (arithmetic average roughness (Sa)) of the polyimide layer is 0.001 nm or more, 100
The thickness is preferably nm or less, more preferably 0.001 nm or more and 10 nm or less, and particularly preferably 0.001 nm or more and 2 nm or less. If the average surface roughness is 0.001 nm or more and 100 nm or less, it is preferable because the present polyimide laminate can be used as a substrate of an electronic device.
The average surface roughness (arithmetic average roughness (Sa)) can be calculated by the following measurement method.
(Method of measuring arithmetic mean roughness (Sa))
The surface observation of the polyimide layer was carried out using a non-contact surface / layer cross-section measurement system VertScan 2.0 (manufactured by Ryoka Systems Co., Ltd.) in the observation field of view (measurement area): 93.97 μm × 71.30 μm, and the surface of the polyimide layer The average surface roughness (arithmetic average roughness Sa) is calculated.

The thickness of the polyimide layer of the polyimide laminate of the present invention is preferably 1 μm or more and 50 μm or less. Further, from the viewpoint of thickness reduction and weight reduction when forming an electronic device, 30 μm or less is more preferable, 25 μm or less is more preferable, and 20 μm or less is particularly preferable.
The thickness of the polyimide precursor layer and the thickness of the polyimide layer obtained by the baking treatment are substantially the same.

<Method of producing polyimide laminate>
The method for producing the laminate according to the present embodiment is not particularly limited as long as the method is produced by transferring the transfer film on a substrate made of glass or metal.
First, a substrate made of glass or metal is prepared, laminated on at least one surface of the transfer film so that the polyimide precursor layer of the transfer film faces the substrate, and then transferred, and then the substrate film is peeled off. Thus, a laminate having a polyimide precursor layer is obtained. By firing the laminate having the polyimide precursor layer, it is possible to produce a polyimide laminate in which the polyimide precursor layer is imidized and the polyimide layer and the substrate made of glass or metal are laminated. Hereinafter, an embodiment of a method for producing a polyimide laminate will be described in more detail.

The transfer step is a step of preparing a substrate made of glass or metal, laminating the transfer film of the present invention on at least one side of the substrate, and transferring the polyimide precursor layer to the substrate made of glass or metal. At this time, the transfer film is laminated so as to face the polyimide precursor layer or the adhesive layer and the substrate made of glass or metal.
The transfer film may be laminated only on either side of the substrate made of glass or metal, or may be laminated on both sides.

  In the transfer step, the present transfer film may be used in the form of an individual sheet cut into a size easy to handle, or may be used by unwinding from the roll state. Moreover, the base material made of glass or metal may be used in the form of a single sheet cut into a size easy to handle, or in the case of a thin base material that can be rolled into a roll, You may unroll and use from a roll state.

As a method of transferring after laminating a transfer film with a substrate made of glass or metal, known methods such as pressing, laminating, roll laminating and the like can be used. For example, the method of heat pressing is suitable for the production of cut sheet-like sheet-fed products, and the method of continuous processing in a heat roll laminating apparatus having a pair or more of rubber rolls and metal rolls is suitable for the production of roll products . In the present embodiment, a known device may be used, for example, a thermal laminating device incorporating a coating device of a polyimide precursor and a drying device for drying the composition after coating on a part of the thermal laminating device. The production of the present transfer film and the thermal lamination may be performed continuously.
In the thermal lamination, the present transfer film is laminated on one side or both sides of a substrate made of glass or metal with the polyimide precursor layer facing the substrate surface, and passed between nip rolls heated to a predetermined temperature. It can be done by

In the method for producing a polyimide laminate of the present invention, the transfer temperature is usually not less than the glass transition temperature of the polyimide precursor layer from the viewpoint of favorably transferring the polyimide precursor layer to a substrate made of glass or metal. The glass transition temperature + 50 ° C. or less of the polyimide precursor layer is preferable. Generally, the glass transition temperature of the polyimide precursor is 50 ° C. or more lower than the glass transition temperature of the polyimide. That is, the transfer temperature is preferably equal to or less than the glass transition temperature (Tg) of the polyimide obtained after firing of the polyimide precursor layer. When the polyimide obtained after firing of the polyimide precursor layer does not have a glass transition temperature, the transfer temperature is preferably 200 ° C. or less. Thus, by lowering the transfer temperature, a general purpose transfer substrate such as polyethylene terephthalate can be used.
In the polyimide precursor layer of the present invention, when the imidization ratio is within the range described above, the elastic modulus of the polyimide precursor layer if the transfer temperature of the transfer step is equal to or higher than the glass transition temperature of the polyimide precursor layer. Is a preferable range for transfer, so that the polyimide precursor layer can be transferred well onto a substrate made of glass or metal. Here, the transfer temperature is a control temperature of a member, such as a nip roll, which sandwiches the transfer film with a substrate made of glass or metal in the transfer step.

The pressing pressure at the time of pressing is preferably 1 MPa or more and 20 MPa or less from the viewpoint of the adhesion between the substrate made of glass or metal and the polyimide layer. By transferring at a pressing pressure in this range, it is difficult to be damaged even if the thin glass described above is used as the substrate, and when the polyimide laminate is formed, sufficient adhesion between the substrate and the polyimide is obtained. Be
The nip roll pressure at the time of lamination is preferably 0.1 MPa · cm or more and 5 MPa · cm or less as the pressure per unit length of the laminate roll from the viewpoint of the adhesion between the substrate made of glass or metal and the polyimide layer. By laminating with a roll pressure in this range, even if the thin glass described above is used as the substrate, it is difficult to be damaged, and when the polyimide laminate is formed, sufficient adhesion between the substrate and the polyimide is obtained. can get. As described above, in the present invention, a thin glass substrate can be used because transfer can be suitably performed even at a low nip roll pressure by setting the specific imidization ratio. In addition, from the viewpoint of suppressing the foaming caused by the residual solvent, the laminating speed is 0.1 m / min. As mentioned above, from a viewpoint which laminates favorably, 50 m / min. It is preferable that it is the following.

  The peeling step is a step of peeling the base film from the laminate obtained in the transfer step. Usually, the base film of the transfer film has good releasability, and the method of peeling is not particularly limited.

  The firing step is a step of firing and curing the polyimide precursor layer of the laminate obtained in the transfer step. The firing temperature and the firing time in the firing step are not particularly limited as long as the imidization reaction of the polyimide precursor proceeds. For example, when the glass transition temperature (Tg) + 50 ° C of the polyimide obtained after firing and the glass transition temperature (Tg) of the polyimide are not clear, the treatment may be performed for about 30 minutes to 1 hour at the use temperature + 50 ° C of the polyimide laminate. . Such heat treatment can be performed using the known heating method described above in the heat treatment method for drying the solvent of the polyamic acid solution. In addition, the reaction may be performed in an inert gas atmosphere such as nitrogen, argon, or helium, or in an active gas atmosphere such as air, or in a vacuum state.

Thus, the present transfer film is laminated and transferred onto a substrate made of glass or metal, and the laminate film having a polyimide precursor layer obtained by peeling the substrate film is fired, a simple method. Thus, a polyimide layer exhibiting high heat resistance can be provided on a substrate made of glass or metal, and a polyimide laminate excellent in handleability can be obtained.

  Moreover, the polyimide laminated body which concerns on this embodiment can be used as a roll-like thing using a well-known winding device. At this time, it is possible to design an apparatus incorporating a winding device so as to take up continuously after curing.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the embodiments described in the following examples.
In addition, the measurement and evaluation in the Example were performed by the following method and reference | standard.
<Measurement and evaluation>
(1) using the imidization infrared spectrophotometer, by total reflection absorption spectroscopy (ATR method), from the absorbance of the imide (1380 cm ^-1) and the absorbance of the benzene ring (1510 cm ^-1), wherein from the absorbance ratio The imidization rate was determined from (a).
In addition, the measurement was performed from the polyimide precursor layer surface side of a transfer film.
Imidation ratio% = (absorbance of 1380 cm ^-1 ) / (absorbance of 1510 cm ^-1 ) x 100 ...
Formula (a)

(2) Coating unevenness (the number of defects in the polyimide precursor on the transfer film)
It was visually confirmed whether or not there is a defect (uncoated portion, void, recessed portion) having a size of 1 mm ² or more in the area 10 cm ² of the polyimide precursor on the transfer film.
×: 1 or more
:: Depending on the measurement location, there are locations with and without defects ○: None

(3) Heat Lamination Suitability The transfer film was heat laminated to a substrate made of glass or metal, and the substrate film was peeled off. It was visually confirmed whether the polyimide precursor layer was laminated on a substrate made of glass or metal.
○: A polyimide precursor layer is laminated on a substrate made of glass or metal.
X: The polyimide precursor layer is not laminated on the substrate made of glass or metal, and is on the substrate film.

(4) Firing unevenness After transferring the polyimide precursor layer to a substrate made of glass or metal, the substrate film is peeled off and baked for 30 minutes at 250 ° C., 30 minutes at 450 ° C. in a nitrogen atmosphere for imidization. In the surface of the polyimide layer after firing, a state where dark and light portions were generated was regarded as firing unevenness. Firing unevenness was visually confirmed.
:: no firing unevenness △: slight firing unevenness observed, but no problem in practical use x: firing unevenness

Example 1
A unit film made of Unitika "U imide varnish AR" with a solid content concentration of 18% is coated on a base film (biaxially stretched film of polyethylene terephthalate ("T100-100" manufactured by Mitsubishi Resins Co., Ltd.) with a bar coater, and 100 for drying oven It was dried at 5 ° C. for 5 minutes to obtain a transfer film having a polyimide precursor layer having an imidization rate of 36% and a thickness of 22 μm.
Next, a glass substrate (“OA-10G” manufactured by Nippon Electric Glass Co., Ltd., thickness: 100 μm) is prepared, and a linear pressure of 0.4 MPa is obtained using a laminator having a metal roll of 200 mm in diameter and a rubber roll of 200 mm in diameter. Heat laminated at 150 ° C. with the transfer film in cm.
After peeling the base film, it was baked in a drying oven for 30 minutes at 250 ° C. and 30 minutes at 450 ° C. under a nitrogen atmosphere to produce a polyimide laminate. The imidation ratio and the coating unevenness were evaluated about the obtained transfer film according to the method of the said description. Moreover, about the obtained polyimide laminated body, according to the method of said description, the heat lamination appropriateness and baking unevenness were evaluated. The results are shown in Table 1.

Example 2
A polyimide laminate was produced in the same manner as in Example 1 except that the drying conditions were changed to 80 ° C. and 4 minutes, and a polyimide precursor layer having an imidation ratio of 20% and a thickness of 18 μm was formed.
The results of evaluation of the obtained transfer film and polyimide laminate in the same manner as in Example 1 are shown in Table 1.

[Example 3]
A polyimide laminate was produced in the same manner as in Example 2 except that 80 μm hot-rolled steel plate was used instead of the glass substrate.
Evaluation was implemented similarly to Example 1 about the obtained transfer film and polyimide laminated body. The results are shown in Table 1.

Example 4
A polyimide laminate was produced in the same manner as in Example 2 except that a polyimide precursor layer having a thickness of 40 μm was formed.
Evaluation was implemented similarly to Example 1 about the obtained transfer film and polyimide laminated body. The results are shown in Table 1.

[Example 5]
A polyimide laminate was produced in the same manner as in Example 1 except that a silicone release-treated film (biaxially stretched film of polyethylene terephthalate ("MRF-38" manufactured by Mitsubishi Resins Co., Ltd.) was used as a base film.
Evaluation was implemented similarly to Example 1 about the obtained transfer film and polyimide laminated body. The results are shown in Table 1.

Comparative Example 1
A polyimide laminate was produced in the same manner as in Example 2 except that the drying conditions were changed to 200 ° C. and 5 minutes, and a polyimide precursor layer having an imidization ratio of 48% was formed.
Evaluation was implemented similarly to Example 1 about the obtained transfer film and polyimide laminated body. The results are shown in Table 1.

  From the results of Examples 1 to 5 and Comparative Example 1, by using the transfer film of the present invention having a polyimide precursor layer having an imidization ratio of 45% or less, a polyimide precursor on a substrate made of glass or metal It was confirmed that the body layer could be transferred well. Moreover, it turned out that the polyimide laminated body in which the polyimide resin which shows high heat resistance, and the base material which consists of glass or a metal was laminated | stacked by baking after transfer is obtained. Furthermore, it was found that the polyimide layer of the obtained polyimide laminate had no defect in appearance.

  The transfer film of the present invention can easily laminate a polyimide layer on a substrate made of glass or metal at a lower temperature than before, and the polyimide laminate produced using the transfer film of the present invention is heat resistant Since it is excellent in the nature and handling nature, it is very useful industrially.

Claims (5)

On at least one surface of the glass or Ranaru substrate, a transfer film and a substrate film and the polyimide precursor layer formed on the base film, the polyimide precursor layer is a single layer imidization A transfer step of laminating a transfer film having a percentage of 45% or less so that the polyimide precursor layer faces the substrate side, and transferring the transferred film;
A method for producing a polyimide laminate, comprising: a peeling step of peeling the base film from the laminate obtained in the step; and a firing step of firing the polyimide precursor layer. The transfer temperature of the transfer step is a temperature below the glass transition temperature of the polyimide when the polyimide obtained by firing the polyimide precursor has a glass transition temperature, or the polyimide obtained by firing the polyimide precursor is The method for producing a polyimide laminate according to claim 1 , wherein the temperature is 200 ° C. or less when it does not have a glass transition temperature. The manufacturing method of the polyimide laminated body of Claim 1 or 2 whose average surface roughness (arithmetic average roughness (Sa)) of the polyimide layer surface of the said polyimide laminated body is 0.001 nm or more and 100 nm or less.   The manufacturing method of the polyimide laminated body of any one of Claims 1-3 whose thickness of the said polyimide precursor layer is 1 micrometer-50 micrometers. Comprising the step of Nikki up the claims 1 to polyimide laminate obtained by the production method according to any one of 4, the manufacturing method of the rolled product.