JP6897690B2 - Method of manufacturing the release layer - Google Patents

Description

The present invention relates to a method for producing a release layer.

In recent years, in addition to the characteristics of thinning and weight reduction, electronic devices are required to be provided with a function of being bendable. For this reason, it is required to use a lightweight flexible plastic substrate instead of the conventional heavy, fragile and inflexible glass substrate.
In particular, in the new generation display, development of an active matrix type full-color TFT display panel using a lightweight flexible plastic substrate (hereinafter referred to as a resin substrate) is required. The technology related to this new generation display is expected to be diverted to various fields such as flexible displays, flexible smartphones, and mirror displays.

Therefore, various methods for manufacturing electronic devices using a resin film as a substrate have begun to be studied, and for new-generation displays, studies are underway on a process in which existing equipment for manufacturing TFT display panels can be diverted.

For example, in Patent Documents 1, 2 and 3, an amorphous silicon thin film layer is formed on a glass substrate, a plastic substrate is formed on the thin film layer, and then a laser is irradiated from the glass substrate side to crystallize the amorphous silicon. , A method of peeling a plastic substrate from a glass substrate by hydrogen gas generated by the crystallization is disclosed.

Further, in Patent Document 4, a peelable layer (described as “transfer layer” in Patent Document 4) is attached to a plastic film by using the techniques disclosed in Patent Documents 1 to 3 to form a liquid crystal display device. The method of completion is disclosed.

However, in the methods disclosed in Patent Documents 1 to 4, particularly the method disclosed in Patent Document 4, it is essential to use a highly translucent substrate in order to transmit laser light, and the method passes through the substrate. In addition, it is necessary to irradiate a laser beam with a relatively large energy sufficient to release hydrogen contained in amorphous silicon, and the irradiation of the laser beam may damage the layer to be peeled off. There is a problem such as that.
Moreover, when the layer to be peeled has a large area, it takes a long time for laser processing, so that it is difficult to increase the productivity of device fabrication.

Japanese Unexamined Patent Publication No. 10-125929 Japanese Unexamined Patent Publication No. 10-125931 International Publication No. 2005/050754 Japanese Unexamined Patent Publication No. 10-125930

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method for producing a release layer that can be peeled off without damaging the resin substrate of a flexible electronic device.

As a result of diligent studies to solve the above problems, the present inventor has made a composition containing a polyamic acid in which one or both of the tetracarboxylic acid terminals are sealed with 2-aminophenol, and an organic solvent. By setting the firing temperature at the time of forming the release layer to a predetermined maximum temperature or higher, excellent adhesion to the substrate, appropriate adhesion to the resin substrate used for the flexible electronic device, and appropriate peelability can be obtained. The present invention has been completed by finding that a peeling layer having can be formed.

That is, the present invention
1. 1. A composition for forming a release layer containing a polyamic acid having both ends derived from tetracarboxylic acid and one or both of these ends being sealed with 2-aminophenol and an organic solvent is placed on a substrate. A method for producing a release layer, which comprises a step of applying and firing at a maximum temperature of 400 ° C. or higher.
2. A method for producing a release layer of 1 which is a polyamic acid obtained by reacting a diamine component containing an aromatic diamine with an acid dianhydride component containing an aromatic tetracarboxylic dianhydride.
3. 3. 2. A method for producing a release layer of 2, wherein the aromatic diamine is an aromatic diamine containing 1 to 5 benzene nuclei.
4. A method for producing an exfoliated layer of 2 or 3 in which the aromatic tetracarboxylic dianhydride is an aromatic tetracarboxylic dianhydride containing 1 to 5 benzene nuclei.
5. A method for manufacturing a flexible electronic device including a resin substrate, which comprises using a release layer formed by using any of the manufacturing methods 1 to 4.
6. A flexible electronic device including a step of applying a resin substrate forming composition on a release layer formed by any of the production methods 1 to 4 and then firing at a maximum temperature of 450 ° C. or higher to form a resin substrate. Manufacturing method,
7. The resin substrate provides a method for manufacturing a flexible electronic device of 5 or 6 which is a polyimide resin substrate.

By adopting the method for producing a release layer of the present invention, it is possible to obtain a release layer having excellent adhesion to a substrate, appropriate adhesion to a resin substrate, and appropriate release property with good reproducibility. Therefore, by implementing the manufacturing method of the present invention, in the manufacturing process of the flexible electronic device, the circuit, etc., without damaging the resin substrate formed on the substrate and the circuit, etc. provided on the substrate, etc. At the same time, the resin substrate can be separated from the substrate. Therefore, the manufacturing method of the present invention can contribute to the simplification of the manufacturing process of the flexible electronic device provided with the resin substrate and the improvement of the yield thereof.

Hereinafter, the present invention will be described in more detail.
The method for producing a release layer according to the present invention comprises a polyamic acid having both ends derived from tetracarboxylic acid and one or both of the two ends being sealed with 2-aminophenol, and an organic solvent. It is characterized by including a step of applying the containing composition for forming a release layer onto a substrate and firing at a maximum temperature of 400 ° C. or higher.
Here, the release layer in the present invention is a layer provided directly above the glass substrate for a predetermined purpose, and as a typical example thereof, in the manufacturing process of a flexible electronic device, a flexible electron composed of a substrate and a resin such as polyimide is used. The resin substrate is provided between the device and the resin substrate in a predetermined process, and the resin substrate can be easily peeled off from the substrate after an electronic circuit or the like is formed on the resin substrate. Examples thereof include a release layer provided for such a purpose.

The polyamic acid used in the present invention can be obtained by reacting one or both of the polymer chain ends of a polyamic acid having both ends derived from tetracarboxylic acid with the amino group of 2-aminophenol and sealing the mixture. Can be done. That is, the polyamic acid obtained here is sealed with one or both of the molecular chain ends with a hydroxy group-containing phenyl group.

Since the polymer terminal has a hydroxy group, the skeleton can be different from that of the flexible substrate used for the upper layer, so that the function of the obtained film as a release layer can be improved.

In the present invention, it is sufficient that a hydroxy group derived from 2-aminophenol is present at either one of the polymer chain ends of the polyamic acid, but a hydroxy group derived from 2-aminophenol is present at both of the polymer chain ends. It is preferred to be present.

The diamine component and acid dianhydride component used in the production of polyamic acid include a diamine component containing an aromatic diamine and an aromatic tetracarboxylic dian from the viewpoint of improving the function of the obtained film as a release layer. A polyamic acid obtained by reacting with an acid dianhydride component containing an anhydride is preferable.

The aromatic diamine is not particularly limited as long as it has two amino groups in the molecule and has an aromatic ring, but an aromatic diamine containing 1 to 5 benzene nuclei is preferable.
Specific examples thereof include 1,4-diaminobenzene (p-phenylenediamine), 1,3-diaminobenzene (m-phenylenediamine), 1,2-diaminobenzene (o-phenylenediamine), and 2,4-diamino. Toluene, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,6-dimethyl-p-phenylenediamine, 2 , 4,6-trimethyl-1,3-phenylenediamine, 2,3,5,6-tetramethyl-p-phenylenediamine, m-xylylene diamine, p-xylylene diamine, 5-trifluoromethylbenzene-1 , 3-Diamine, 5-trifluoromethylbenzene-1,2-diamine, 3,5-bis (trifluoromethyl) benzene-1,2-diamine, etc. Diamine with one benzene nucleus; 1,2-naphthalenediamine , 1,3-naphthalenediamine, 1,4-naphthalenediamine, 1,5-naphthalenediamine, 1,6-naphthalenediamine, 1,7-naphthalenediamine, 1,8-naphthalenediamine, 2,3-naphthalenediamine, 2,6-naphthalenediamine, 4,4'-biphenyldiamine, 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-dicarboxy-4,4'-diaminodiphenylmethane, 3,3', 5,5'-tetramethyl-4,4'-diaminodiphenylmethane, 4,4'-diaminobenzanilide, 3,3' -Dichlorobenzidine, 3,3'-dimethylbenzidine, 2,2'-dimethylbenzidine, 3,3'-diaminodiphenylmethane, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 2,2-bis ( 3-aminophenyl) propane, 2,2-bis (4-aminophenyl) propane, 2,2-bis (3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2, 2-Bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 3,3'-diaminodiphenylsulfoxide, 3,4'-diaminodiphenylsulfoxide, 4,4'-diamino Diphenyl sulfoxide, 3,3'-bis (trifluoromethyl) biphenyl-4,4'-diamine, 3,3', 5,5'-tetrafluorobiphenyl-4,4'- Diamine with two benzene nuclei such as diamine, 4,4'-diaminooctafluorobiphenyl, 2- (3-aminophenyl) -5-aminobenzimidazole, 2- (4-aminophenyl) -5-aminobenzoxol 1,5-Diaminoanthracene, 2,6-diaminoanthracene, 9,10-diaminoanthracene, 1,8-diaminophenylene, 2,7-diaminophenylene, 3,6-diaminophenanthrene, 9,10-diaminophenylene, 1,3-bis (3-aminophenyl) benzene, 1,3-bis (4-aminophenyl) benzene, 1,4-bis (3-aminophenyl) benzene, 1,4-bis (4-aminophenyl) Benzene, 1,3-bis (3-aminophenyl sulfide) benzene, 1,3-bis (4-aminophenyl sulfide) benzene, 1,4-bis (4-aminophenyl sulfide) benzene, 1,3-bis ( 3-Aminophenylsulfone) Benzene, 1,3-bis (4-aminophenylsulfone) benzene, 1,4-bis (4-aminophenylsulfone) benzene, 1,3-bis [2- (4-aminophenyl) Isopropyl] benzene, 1,4-bis [2- (3-aminophenyl) isopropyl] benzene, 1,4-bis [2- (4-aminophenyl) isopropyl] benzene, 4,4''-diamino-p- Examples thereof include diamines having three benzene nuclei such as terphenyl and 4,4''-diamino-m-terphenyl, but are not limited thereto. These can be used alone or in combination of two or more. In the present invention, it is preferable to use the aromatic diamine that does not contain an ether bond and an ester bond.

Above all, from the viewpoint of improving the function of the obtained film as a release layer, an aromatic ring composed only of an aromatic ring and a heteroaromatic ring having no substituent such as a methyl group on the aromatic ring and the heterocycle condensed therein. Group diamines are preferred. Specifically, p-phenylenediamine, m-phenylenediamine, 2- (3-aminophenyl) -5-aminobenzimidazole, 2- (4-aminophenyl) -5-aminobenzooxol, 4,4' '-Diamino-p-terphenyl and the like are preferred.

The aromatic tetracarboxylic acid dianhydride is not particularly limited as long as it has two dicarboxylic acid anhydride moieties in the molecule and has an aromatic ring, but an aromatic tetracarboxylic acid dianhydride containing 1 to 5 benzene nuclei. Group tetracarboxylic acid dianhydrides are preferred.

Specific examples thereof include pyromellitic dianhydride, benzene-1,2,3,4-tetracarboxylic dianhydride, naphthalene-1,2,3,4-tetracarboxylic dianhydride, and naphthalene-1. , 2,5,6-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, naphthalene-1,2,7,8-tetracarboxylic dianhydride, naphthalene- 2,3,5,6-tetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, biphenyl -2,2', 3,3'-tetracarboxylic dianhydride, biphenyl-2,3,3', 4'-tetracarboxylic dianhydride, biphenyl-3,3', 4,4'-tetra Carcarboxylic dianhydride, anthracene-1,2,3,4-tetracarboxylic dianhydride, anthracene-1,2,5,6-tetracarboxylic dianhydride, anthracene-1,2,6,7- Tetetracarboxylic dianhydride, anthracene-1,2,7,8-tetracarboxylic dianhydride, anthracene-2,3,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,3,4 -Tetetracarboxylic dianhydride, phenanthrene-1,2,5,6-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1,2,7, 8-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, phenanthrene-2,3,5,6-tetracarboxylic dianhydride, phenanthrene-2,3,6 , 7-Tetetracarboxylic dianhydride, phenanthrene-2,3,9,10-tetracarboxylic dianhydride, phenanthrene-3,4,5,6-tetracarboxylic dianhydride, phenanthrene-3,4 Examples thereof include, but are not limited to, 9,10-tetracarboxylic dianhydride. These can be used alone or in combination of two or more.

Of these, aromatic carboxylic acid dianhydrides having one or two benzene nuclei are preferable from the viewpoint of improving the function of the obtained film as a release layer. Specifically, the aromatic tetracarboxylic dianhydride represented by any of the formulas (C1) to (C12) is preferable, and any of the formulas (C1) to (C7) and (C9) to (C11) The aromatic tetracarboxylic dianhydride shown is more preferred.

Further, from the viewpoint of improving the flexibility, heat resistance, etc. of the obtained release layer, the diamine component used in the present invention may contain a diamine other than the aromatic diamine, and the tetracarboxylic dianhydride component used in the present invention may contain a diamine. , Tetracarboxylic dianhydride other than aromatic tetracarboxylic dianhydride may be contained.

In the present invention, the amount of aromatic diamine in the diamine component is preferably 70 mol% or more, more preferably 80 mol% or more, even more preferably 90 mol% or more, still more preferably 95 mol% or more, most preferably 95 mol% or more. It is 100 mol%. The amount of aromatic tetracarboxylic dianhydride in the tetracarboxylic acid component is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, still more preferably 95 mol% or more. As mentioned above, it is most preferably 100 mol%. By adopting such a usage amount, it is possible to obtain a film having excellent adhesion to the substrate, appropriate adhesion to the resin substrate, and appropriate peelability with good reproducibility.

By reacting the diamine component described above with the tetracarboxylic dianhydride component and then reacting the obtained polyamic acid with 2-aminophenol, it is contained in the composition for forming a release layer of the present invention. A polyamic acid whose polymer chain terminal is sealed with 2-aminophenol can be obtained.

The charging ratio of the diamine component and the tetracarboxylic dianhydride component cannot be unconditionally specified because it is appropriately determined in consideration of the target molecular weight and molecular weight distribution, the type of diamine, the type of tetracarboxylic dianhydride, and the like. Since both ends of the molecular chain derived from tetracarboxylic acid are used, it is preferable to increase the number of moles of the tetracarboxylic dianhydride component with respect to the number of moles of the diamine component. As a specific molar ratio, 1.02 to 3.0 mol of the tetracarboxylic dianhydride component is preferable, 1.07 to 2.5 mol is more preferable, and 1.1 to 1.5 mol is more preferable with respect to 1 mol of the diamine component. 2.0 mol is even more preferred.

The organic solvent used in the synthesis of the polyamic acid and the sealing of the molecular chain terminal of the synthesized polyamic acid is not particularly limited as long as it does not adversely affect the reaction, and specific examples thereof include m-cresol, 2-pyrrolidone, and N-. Methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N, N-dimethylacetamide, N, N-dimethylformamide, 3-methoxy-N, N-dimethylpropylamide, 3- Ethoxy-N, N-dimethylpropylamide, 3-propoxy-N, N-dimethylpropylamide, 3-isopropoxy-N, N-dimethylpropylamide, 3-butoxy-N, N-dimethylpropylamide, 3-sec Examples thereof include -butoxy-N, N-dimethylpropylamide, 3-tert-butoxy-N, N-dimethylpropylamide, γ-butyrolactone and the like. The organic solvent may be used alone or in combination of two or more.

In particular, since the organic solvent used in the reaction dissolves diamine, tetracarboxylic dianhydride and polyamic acid well, the amides represented by the formula (S1), the amides represented by the formula (S2) and the formula (S2). At least one selected from the amides represented by S3) is preferable.

In the formula, R ¹ and R ² represent alkyl groups having 1 to 10 carbon atoms independently of each other. R ³ represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. h represents a natural number, preferably 1 to 3, more preferably 1 or 2.

Alkyl groups having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, s-butyl group, t-butyl group, n-pentyl group and n-. Examples thereof include a hexyl group, an n-heptyl group, an n-octyl group, an n-nonyl group and an n-decyl group. Of these, an alkyl group having 1 to 3 carbon atoms is preferable, and an alkyl group having 1 or 2 carbon atoms is more preferable.

The reaction temperature at the time of synthesizing the polyamic acid may be appropriately set in the range from the melting point to the boiling point of the solvent to be used, and is usually about 0 to 100 ° C. From the viewpoint of maintaining a high content of the polyamic acid unit, the temperature can be preferably about 0 to 70 ° C, more preferably about 0 to 60 ° C, and further preferably about 0 to 50 ° C. The reaction time cannot be unconditionally defined because it depends on the reaction temperature and the reactivity of the raw material, but it is usually about 1 to 100 hours.

The reaction temperature at the time of sealing the molecular chain ends of the polyamic acid may be appropriately set in the range from the melting point to the boiling point of the solvent to be used, as in the case of synthesizing the polyamic acid, and is usually about 0 to 100 ° C. From the viewpoint of reliably sealing the molecular chain ends of the synthesized polyamic acid, the temperature can be preferably about 0 to 70 ° C, more preferably about 0 to 60 ° C, and even more preferably about 0 to 50 ° C. The reaction time cannot be unconditionally defined because it depends on the reaction temperature and the reactivity of the raw material, but it is usually about 1 to 100 hours.

The weight average molecular weight of the polyamic acid obtained in this manner, in which one or both of the ends of the molecular chain is sealed with 2-aminophenol, is usually about 5,000 to 500,000, but can be obtained. From the viewpoint of improving the function of the film as a release layer, it is preferably about 6,000 to 200,000, more preferably about 7,000 to 150,000. In the present invention, the weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography (GPC).

In the present invention, a solution obtained by diluting or concentrating the reaction solution after end-sealing as it is can be used as the composition for forming a release layer of the present invention. The reaction solution may be filtered if necessary. By filtering, not only can the mixing of impurities that can cause deterioration of the adhesion and peelability of the obtained release layer be reduced, but also a composition for forming the release layer can be efficiently obtained. Further, after isolating the polyamic acid from the reaction solution, it may be dissolved in a solvent again to obtain a composition for forming a release layer. Examples of the solvent in this case include the organic solvent used in the above-mentioned reaction.

The solvent used for dilution is not particularly limited, and specific examples thereof include the same as the specific example of the reaction solvent for the reaction. The solvent used for dilution may be used alone or in combination of two or more. Among them, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, N-ethyl-2 because it dissolves polyamic acid well. -Pyrrolidone and γ-butyrolactone are preferable, and N-methyl-2-pyrrolidone is more preferable.

Further, even if the solvent does not dissolve the polyamic acid by itself, it can be mixed with the composition for forming a release layer of the present invention as long as the polyamic acid does not precipitate. In particular, ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, 1-butoxy-2-propanol, 1-phenoxy. -2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-ethoxy Propoxy) Solvents having low surface tension such as propanol, methyl lactate, ethyl lactate, n-propyl lactate, n-butyl lactate, and isoamyl lactate can be appropriately mixed. It is known that this improves the uniformity of the coating film when it is applied to a substrate, and it is also suitably used in the composition for forming a release layer of the present invention.

The concentration of the polyamic acid in the composition for forming a release layer of the present invention is appropriately set in consideration of the thickness of the release layer to be produced, the viscosity of the composition, etc., but is usually about 1 to 30% by mass, preferably about 1 to 30% by mass. It is about 1 to 20% by mass. With such a concentration, a peeling layer having a thickness of about 0.05 to 5 μm can be obtained with good reproducibility. The concentration of the polyamic acid is adjusted by adjusting the amount of diamine and tetracarboxylic acid dianhydride which are the raw materials of the polyamic acid, filtering the reaction solution and then diluting or concentrating the filtrate, and using the isolated polyamic acid as a solvent. It can be adjusted by adjusting the amount of the solution when it is dissolved in.

The viscosity of the release layer forming composition of the present invention is appropriately set in consideration of the thickness of the release layer to be produced, etc., but in particular, a film having a thickness of about 0.05 to 5 μm can be obtained with good reproducibility. Usually, it is about 10 to 10,000 mPa · s at 25 ° C., preferably about 20 to 5,000 mPa · s.

Here, the viscosity can be measured using a commercially available viscometer for measuring the viscosity of a liquid, for example, with reference to the procedure described in JIS K7117-2, under the condition that the temperature of the composition is 25 ° C. .. Preferably, a conical plate type (cone plate type) rotational viscometer is used as the viscometer, and 1 ° 34'x R24 is preferably used as the standard cone rotor with the same type viscometer, and the temperature of the composition is 25. It can be measured under the condition of ° C. Examples of such a rotational viscometer include TVE-25L manufactured by Toki Sangyo Co., Ltd.

In addition to the polyamic acid and the organic solvent, the composition for forming a release layer of the present invention may contain, for example, a cross-linking agent or the like in order to improve the film strength.

By applying the composition for forming a release layer described above onto a substrate and then thermally imidizing the polyamic acid by a firing method including a step of firing at a maximum temperature of 400 ° C. or higher, excellent adhesion to the substrate is achieved. A release layer made of a polyimide film having an appropriate adhesion to a resin substrate and an appropriate release property can be obtained.
In the present invention, the maximum temperature at the time of firing is not particularly limited as long as it is in the range of 400 ° C. or higher and the heat resistant temperature of polyimide or lower, but the adhesion to the substrate and the appropriateness to the resin substrate are appropriate. Considering that the adhesiveness and peelability are improved, 450 ° C. or higher is preferable, and 500 ° C. or higher is more preferable. The upper limit is usually about 550 ° C, but preferably about 510 ° C. By setting the heating temperature in the above range, it is possible to sufficiently proceed the imidization reaction while preventing the resulting film from becoming fragile.
The heating time cannot be unconditionally specified because it varies depending on the heating temperature, but is usually 1 minute to 5 hours. The imidization rate may be in the range of 50 to 100%.

Further, the firing temperature may include a step of firing at a temperature lower than that as long as the maximum temperature is within the above range.
As a preferable example of the heating mode in the present invention, there is a method of heating at 50 to 150 ° C., then gradually increasing the heating temperature as it is, and finally heating at 400 ° C. or higher. In particular, as a more preferable example of the heating mode, there is a method of heating at 50 to 100 ° C., heating at more than 100 ° C. to less than 400 ° C., and heating at 400 ° C. or higher. Further, as another more preferable example of the heating embodiment, after heating at 50 to 150 ° C., heating at more than 150 ° C. to 350 ° C., then heating at more than 350 ° C. to 450 ° C., and finally over 450 ° C. to 510 ° C. A method of heating at ° C can be mentioned.

Further, as a preferable example of the heating mode in consideration of the firing time, after heating at 50 to 150 ° C. for 1 minute to 2 hours, the heating temperature is gradually increased as it is, and finally at 400 ° C. or higher for 30 minutes. A method of heating for ~ 4 hours can be mentioned. In particular, as a more preferable example of the heating mode, heating is performed at 50 to 100 ° C. for 1 minute to 2 hours, above 100 ° C. to less than 400 ° C. for 5 minutes to 2 hours, and at 400 ° C. or higher for 30 minutes to 4 hours. There is a method to do. Further, as another more preferable example of the heating mode, after heating at 50 to 150 ° C. for 1 minute to 2 hours, the temperature exceeds 150 ° C. to 350 ° C. for 5 minutes to 2 hours, and then 350 ° C. to 450 ° C. for 30 minutes. There is a method of heating for about 4 hours, and finally over 450 ° C. to 510 ° C. for 30 minutes to 4 hours.

When the release layer of the present invention is formed on the substrate, the release layer may be formed on a part surface of the substrate or may be formed on the entire surface. Examples of forming the release layer on a part of the surface of the substrate include forming the release layer only in a predetermined range on the surface of the substrate, and forming the release layer in a pattern such as a dot pattern or a line-and-space pattern on the entire surface of the substrate. There are modes of formation and the like. In the present invention, the substrate means a substrate on which the composition for forming a release layer of the present invention is coated, which is used for manufacturing a flexible electronic device or the like.

Examples of the substrate (base material) include glass, metal (silicon wafer, etc.), slate, and the like. In particular, glass is preferable because the release layer of the present invention has sufficient adhesion to the substrate. The surface of the substrate may be made of a single material or may be made of two or more materials. A mode in which the surface of the substrate is composed of two or more materials is a mode in which a certain range of the surface of the substrate is composed of a certain material and the remaining surface is composed of other materials, and a dot pattern is formed on the entire surface of the substrate. , Line-and-space pattern, and other patterns in which the material is present in other materials.

The method for applying the composition for forming a release layer of the present invention to a substrate is not particularly limited, but for example, a cast coating method, a spin coating method, a blade coating method, a dip coating method, a roll coating method, and a bar coating method are used. Examples include a method, a die coating method, an inkjet method, and a printing method (letter plate, intaglio plate, lithographic plate, screen printing, etc.).

Examples of the appliance used for heating include a hot plate and an oven. The heating atmosphere may be under air or under an inert gas, and may be under normal pressure or reduced pressure.

The thickness of the release layer is usually about 0.01 to 50 μm, preferably about 0.05 to 20 μm from the viewpoint of productivity. The desired thickness is achieved by adjusting the thickness of the coating film before heating.

The release layer described above has excellent adhesion to a substrate, particularly a glass substrate, appropriate adhesion to a resin substrate, and appropriate peelability. Therefore, the release layer of the present invention detaches the resin substrate from the substrate together with the circuit and the like formed on the resin substrate without damaging the resin substrate of the device in the manufacturing process of the flexible electronic device. It can be preferably used to make it.

Hereinafter, an example of a method for manufacturing a flexible electronic device using the release layer of the present invention will be described.
Using the composition for forming a release layer of the present invention, a release layer is formed on a glass substrate by the above-mentioned method. A resin substrate forming solution for forming a resin substrate is applied onto the release layer, and the coating film is fired to obtain a resin substrate fixed to the glass substrate via the release layer of the present invention. Form.
The firing temperature of the coating film is appropriately set according to the type of resin and the like, but in the present invention, the maximum temperature at the time of firing is preferably 450 ° C. or higher, and is preferably 480 ° C. or higher. More preferably, it is more preferably 490 ° C. or higher, and even more preferably 500 ° C. or higher. By setting the maximum temperature at the time of firing during the production of the resin substrate within this range, the adhesion between the release layer as the base and the substrate, and the appropriate adhesion and peelability between the release layer and the resin substrate are further improved. be able to.
In this case as well, as long as the maximum temperature is within the above range, the step of firing at a temperature lower than that may be included.

As a preferable example of the heating mode at the time of producing the resin substrate, there is a method of heating at 50 to 150 ° C., then gradually increasing the heating temperature as it is, and finally heating at 450 ° C. or higher. In particular, as a more preferable example of the heating mode, there is a method of heating at 50 to 100 ° C., heating at more than 100 ° C. to less than 400 ° C., and heating at 450 ° C. or higher. Further, as another more preferable example of the heating mode, after heating at 50 to 100 ° C., heating at more than 100 ° C. to 200 ° C., then above 200 ° C. to less than 300 ° C., and then heating at 300 ° C. to less than 400 ° C. Then, a method of heating at 400 ° C. to less than 450 ° C. and finally heating at 450 to 510 ° C. can be mentioned.

Further, as a preferable example of the heating mode in consideration of the firing time, after heating at 50 to 150 ° C. for 1 minute to 2 hours, the heating temperature is gradually increased as it is, and finally at 450 ° C. or higher for 30 minutes. A method of heating for ~ 4 hours can be mentioned. In particular, as a more preferable example of the heating mode, heating is performed at 50 to 100 ° C. for 1 minute to 2 hours, above 100 ° C. to below 400 ° C. for 5 minutes to 2 hours, and at 450 ° C. or higher for 30 minutes to 4 hours. There is a method to do. Further, as another more preferable example of the heating embodiment, after heating at 50 to 100 ° C. for 1 minute to 2 hours, the temperature exceeds 100 ° C. to 200 ° C. for 5 minutes to 2 hours, and then the temperature exceeds 200 ° C. to less than 300 ° C. 30. Examples include a method of heating for minutes to 4 hours, 30 minutes to 4 hours at 300 ° C. to less than 400 ° C., 30 minutes to 4 hours at 400 ° C. to less than 450 ° C., and finally 30 minutes to 4 hours at 450 to 510 ° C.

The resin substrate covers the entire release layer, and forms the substrate with an area larger than the area of the release layer. Examples of the resin substrate include a resin substrate made of polyimide, which is a typical resin substrate for flexible electronic devices, and examples of the resin solution for forming the resin substrate include a polyimide solution and a polyamic acid solution. The method for forming the resin substrate may be a conventional method.

Next, a desired circuit is formed on the resin substrate fixed to the substrate via the release layer of the present invention, and then, for example, the resin substrate is cut along the release layer, and the resin substrate is formed together with this circuit. The resin substrate and the substrate are separated by peeling from the peeling layer. At this time, a part of the substrate may be cut together with the release layer.

Japanese Patent Application Laid-Open No. 2013-147599 reports that the laser lift-off method (LLO method), which has been used in the manufacture of high-brightness LEDs and three-dimensional semiconductor packages, is applied to the manufacture of flexible displays. .. The LLO method is characterized in that a ray having a specific wavelength, for example, a ray having a wavelength of 308 nm is emitted from the glass substrate side from a surface opposite to the surface on which a circuit or the like is formed. The irradiated light rays pass through the glass substrate, and only the polymer (polyimide) in the vicinity of the glass base absorbs the light rays and evaporates (sublimates). As a result, the resin substrate can be selectively peeled from the glass substrate without affecting the circuit or the like provided on the resin substrate, which determines the performance of the display.

Since the release layer of the present invention has a feature of sufficiently absorbing light rays having a specific wavelength (for example, 308 nm) to which the LLO method can be applied, it can be used as a sacrificial layer of the LLO method. Therefore, when a desired circuit is formed on a resin substrate fixed to a glass substrate via a release layer formed by using the composition in the present invention, and then an LLO method is carried out to irradiate a light beam of 308 nm. Only the release layer absorbs this light beam and evaporates (sublimates). As a result, the release layer is sacrificed (acts as a sacrifice layer), and the resin substrate can be selectively peeled from the glass substrate.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

[1] Abbreviation for compound NMP: N-methylpyrrolidone BCS: Butyl cellosolve p-PDA: p-phenylenediamine 2AP: 2-aminophenol BPDA: 3,3-4,4-biphenyltetracarboxylic dianhydride PMDA: Pyromerit Acid dianhydride

[2] Measurement of weight average molecular weight and molecular weight distribution For the weight average molecular weight (hereinafter abbreviated as Mw) and molecular weight distribution of the polymer, an elution solvent was used using a GPC apparatus (Shodex® columns KF803L and KF805L) manufactured by JASCO Corporation. Dimethylformamide was measured at a flow rate of 1 ml / min and a column temperature of 50 ° C. In addition, Mw was a polystyrene conversion value.

[3] Polymer synthesis A polyamic acid was synthesized by the following method.
The polymer was not isolated from the obtained polymer-containing reaction solution, and the reaction solution was diluted to prepare a resin substrate forming composition or a peeling layer forming composition as described later.

<Synthesis example S1 polyamic acid (synthesis of S1)>
3.176 g (0.02937 mol) of p-PDA was dissolved in 88.2 g of NMP, 8.624 g (0.02931 mol) of BPDA was added, and then the reaction was carried out at 23 ° C. for 24 hours under a nitrogen atmosphere. The Mw of the obtained polymer was 107,300 and the molecular weight distribution was 4.6.

<Synthesis example L1 Synthesis of polyamic acid (L1)>
1.507 g (0.0139 mol) of p-PDA was dissolved in 43.2 g of NMP, 3.166 g (0.01452 mol) of PMDA was added, and then the reaction was carried out at 23 ° C. for 2 hours under a nitrogen atmosphere. Then, 0.127 g (0.0012 mol) of 2AP was further added, and the mixture was reacted at 23 ° C. for 24 hours under a nitrogen atmosphere. The Mw of the obtained polymer was 48,500 and the molecular weight distribution was 2.05.

<Synthesis example L2 Synthesis of polyamic acid (L2)>
1.119 g (0.01103 mol) of p-PDA was dissolved in 35.2 g of NMP, 3.006 g (0.01378 mol) of PMDA was added, and then the reaction was carried out at 23 ° C. for 2 hours under a nitrogen atmosphere. Then, 0.602 g (0.00551 mol) of 2AP was further added, and the mixture was reacted at 23 ° C. for 24 hours under a nitrogen atmosphere. The Mw of the obtained polymer was 11,700 and the molecular weight distribution was 1.76.

<Synthesis example L3 polyamic acid (L3) synthesis>
0.681 g (0.00629 mol) of p-PDA was dissolved in 35.2 g of NMP, 2.746 g (0.01259 mol) of PMDA was added, and then the reaction was carried out at 23 ° C. for 2 hours under a nitrogen atmosphere. Then, 1.373 g (0.012588 mol) of 2AP was further added, and the reaction was carried out at 23 ° C. for 24 hours under a nitrogen atmosphere. The Mw of the obtained polymer was 8,000 and the molecular weight distribution was 1.57.

<Comparative Synthesis Example HL1 Synthesis of Polyamic Acid (HL1)>
1.29 g (0.00107 mol) of p-PDA was dissolved in 43.2 g of NMP, 3.509 g (0.00119 mol) of BPDA was added, and then the reaction was carried out at 23 ° C. for 24 hours under a nitrogen atmosphere. The Mw of the obtained polymer was 34,000 and the molecular weight distribution was 2.03.

<Comparative Synthesis Example HL2 Synthesis of Polyamic Acid (HL2)>
1.325 g (0.00123 mol) of p-PDA was dissolved in 36 g of NMP, 2.674 g (0.00123 mol) of PMDA was added, and then the reaction was carried out at 23 ° C. for 2 hours under a nitrogen atmosphere. Unfortunately, it gelled and could not be used.

[4] Preparation of Resin Substrate Forming Composition The reaction solutions obtained in Synthesis Example S1 were used as they were as the resin substrate forming composition.

[5] Preparation of composition for forming a release layer [Example 1-1]
BCS and NMP were added to the reaction solution obtained in Synthesis Example L1 and diluted so that the polymer concentration was 5 wt% and BCS was 20% by mass to obtain a composition for forming a release layer.

[Examples 1-2 to 1-3]
A composition for forming a release layer was obtained in the same manner as in Example 1-1, except that the reaction solutions obtained in Synthesis Examples L2 to L3 were used instead of the reaction solutions obtained in Synthesis Example L1. It was.

[Comparative Example 1-1]
A composition for forming a release layer was obtained in the same manner as in Example 1-1 except that the reaction solution obtained in Comparative Synthesis Example HL1 was used instead of the reaction solution obtained in Synthesis Example L1. ..

[6] Preparation of Release Layer and Resin Substrate [Example 2-1]
Using a spin coater (condition: about 30 seconds at a rotation speed of 3,000 rpm), the release layer forming composition L1 obtained in Example 1-1 was subjected to a 100 mm × 100 mm glass substrate as a glass substrate (the same applies hereinafter). Applied on top.
Then, the obtained coating film is heated at 100 ° C. for 2 minutes using a hot plate, and then heated at 300 ° C. for 30 minutes using an oven to raise the heating temperature to 400 ° C. (10 ° C./min). ), Heat at 400 ° C. for 30 minutes, further heat up to 500 ° C. (10 ° C./min), and heat at 500 ° C. for 10 minutes to form a release layer with a thickness of about 0.1 μm on the glass substrate. , A glass substrate with a release layer was obtained. During the temperature rise, the substrate with the film was not taken out of the oven, but was heated in the oven.

Using a bar coater (gap: 250 μm), the resin substrate forming composition S2 was applied onto the release layer (resin thin film) on the glass substrate obtained above. Then, the obtained coating film is heated at 80 ° C. for 30 minutes using a hot plate, then used in an oven to create a nitrogen atmosphere, and then heated at 140 ° C. for 30 minutes to raise the heating temperature to 210 ° C. Warm (2 ° C / min, the same applies hereinafter), raise the heating temperature to 300 ° C for 30 minutes at 210 ° C, raise the heating temperature to 400 ° C for 30 minutes at 300 ° C, and raise the heating temperature to 400 ° C for 30 minutes at 400 ° C. The heating temperature was raised to 500 ° C. and heated at 500 ° C. for 60 minutes to form a polyimide resin substrate having a thickness of about 20 μm on the release layer to obtain a resin substrate and a glass substrate with a release layer. During the temperature rise, the substrate with the film was not removed from the oven, but was heated in the oven.

[Examples 2-2 to 2-3]
Except that the release layer forming compositions L2 and L3 obtained in Examples 1-2 to 1-3 were used instead of the release layer forming composition L1 obtained in Example 1-1, respectively. A release layer and a polyimide resin substrate were formed in the same manner as in Example 2-1 to obtain a glass substrate with a release layer and a resin substrate / glass substrate with a release layer.

[Comparative Example 2-1]
The same as in Example 2-1 except that the release layer forming composition HL1 obtained in Comparative Example 1-1 was used instead of the release layer forming composition L1 obtained in Example 1-1. By the method, a release layer and a polyimide resin substrate were formed, and a glass substrate with a release layer and a resin substrate / a glass substrate with a release layer were obtained.

[7] Evaluation of peelability With respect to the glass substrate with a peeling layer obtained in Examples 2-1 to 2-3 and Comparative Example 2-1 above, the peelability between the peeling layer and the glass substrate is confirmed by the following method. did. The following tests were performed on the same glass substrate.

<Cross-cut test peelability evaluation of resin thin film>
The release layers on the glass substrate with the release layer obtained in Examples 2-1 to 2-3 and Comparative Example 2-1 were cross-cut (1 mm intervals in length and width, the same applies hereinafter), and 100 muscats were performed. That is, by this cross cut, 100 squares of 1 mm square were formed.
Then, an adhesive tape was attached to the 100 muscat portion, the tape was peeled off, and the peelability was evaluated based on the following criteria (5B to 0B, B, A, AA). The results are shown in Table 1.
<Criteria>
5B: 0% peeling (no peeling)
4B: Peeling less than 5% 3B: Peeling less than 5-15% 2B: Peeling less than 15-35% 1B: Peeling less than 35-65% 0B: Peeling less than 65% -80% B: 80% -95 Peeling less than% A: Peeling from 95% to less than 100% AA: Peeling from 100% (all peeling)

<Evaluation of peelability of resin substrate>
The resin substrate of the resin substrate / glass substrate with a release layer obtained in Examples 2-1 to 2-3 and Comparative Example 2-1 was cut into strips having a width of 25 mm using a cutter. Then, a cellophane tape was attached to the tip of the cut resin substrate, and this was used as a test piece. This test piece was subjected to a peeling test using a push-pull tester manufactured by Atonic Co., Ltd. so that the peeling angle was 90 °, and the peelability was evaluated based on the following criteria. The results are shown in Table 1.
<Criteria>
5B: 0% peeling (no peeling)
4B: Peeling less than 5% 3B: Peeling less than 5-15% 2B: Peeling less than 15-35% 1B: Peeling less than 35-65% 0B: Peeling less than 65% -80% B: 80% -95 Peeling less than% A: Peeling from 95% to less than 100% AA: Peeling from 100% (all peeling)

From the results in Table 1, in the release layer of Examples 2-1 to 2-3, only the resin substrate could be peeled off without peeling the release layer from the glass substrate, but could not be peeled off in Comparative Example 2-1. It was confirmed that.

Claims (7)

A composition for forming a release layer containing a polyamic acid having both ends derived from tetracarboxylic acid and one or both of these ends being sealed with 2-aminophenol and an organic solvent is placed on a substrate. A method for producing a release layer, which comprises a step of applying and firing at a maximum temperature of 400 ° C. or higher. The method for producing a release layer according to claim 1, wherein the polyamic acid is a polyamic acid obtained by reacting a diamine component containing an aromatic diamine with an acid dianhydride component containing an aromatic tetracarboxylic dianhydride. .. The method for producing a release layer according to claim 2, wherein the aromatic diamine is an aromatic diamine containing 1 to 5 benzene nuclei. The method for producing a release layer according to claim 2 or 3, wherein the aromatic tetracarboxylic dianhydride is an aromatic tetracarboxylic dianhydride containing 1 to 5 benzene nuclei. A method for manufacturing a flexible electronic device including a resin substrate, which comprises using a release layer formed by using the manufacturing method according to any one of claims 1 to 4. A step of applying a resin substrate forming composition onto a release layer formed by the production method according to any one of claims 1 to 4, and then firing at a maximum temperature of 450 ° C. or higher to form a resin substrate. A method of manufacturing a flexible electronic device including. The method for manufacturing a flexible electronic device according to claim 5 or 6, wherein the resin substrate is a polyimide resin substrate.