TWI780171B - Composition for forming flexible device substrate - Google Patents

Abstract

[式中，B¹ 表示選自下述式(X-1)~(X-11)所成之群之4價基]

。The object of the present invention is to provide a composition for forming a flexible device substrate, which can impart excellent performances such as maintaining excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, and can be obtained by mechanical peeling (MD method). ) A resin film having excellent performance as a base film of a flexible device substrate such as a flexible display substrate, which is easily peeled off. The flexible device substrate-forming composition contains a tetracarboxylic dianhydride component using an alicyclic tetracarboxylic dianhydride represented by the following formula (C1) and the following formula (D1) and a tetracarboxylic dianhydride component including the following formula (E1 ) represents polyimide and organic solvent obtained from the diamine component of stilbene diamine,

[In the formula, B1 represents ^a quaternary group selected from the group formed by the following formulas (X-1) to (X-11)]

.

Description

Composition for forming flexible device substrate

The present invention relates to a composition for forming a substrate of a flexible device, and more specifically, to a flexible device such as a flexible display that can be preferably used in a step of peeling a substrate from a carrier base material using a mechanical peeling method The composition of the formation of the substrate.

In recent years, with the rapid advancement of electronics such as liquid crystal displays and organic electroluminescent displays, thinning and lightening of devices, and further, flexibility is required. In these devices, various electronic components such as thin film transistors or transparent electrodes are formed on a glass substrate, but by replacing the glass material with a soft and lightweight resin material, the device itself can be made thinner or lighter. , Flexibility. Under such circumstances, polyimide has attracted much attention as a substitute material for glass. Furthermore, not only flexibility but also the same transparency as glass is required in many cases for polyimide which is advantageous for this use. In order to achieve these characteristics, semi-alicyclic polyimides or fully alicyclic polyimides obtained by using alicyclic diamine components or alicyclic anhydride components as raw materials have been reported (see, for example, Patent Documents 1 to 3). ).

On the other hand, it has been reported that in the manufacture of flexible displays, the mechanical delamination method (MD method) which has been used in the manufacture of solar power generation devices to date can be used to detach polymer substrates from glass supports better (such as non-patent Literature 1). In the manufacture of flexible displays, it is necessary to set a polymer substrate made of polyimide on a glass carrier, then form a circuit including electrodes and the like on the substrate, and finally remove the substrate from the glass together with the circuit. Carrier stripped. It has been reported that in this peeling step, the MD method is used, that is, after cutting the four sides of the polymer (polyimide) film on the glass carrier, by suction, it is possible to select the circuit without causing damage to the circuit on the substrate. Debonding of the substrate from the glass carrier is performed. For the substrate of the display, it is required to have a low birefringence that does not affect the optical anisotropy of the polarized light passing through the transparent substrate. Here, the polyimide having a bulky backbone or a bulky side chain, since the distance between the polymer chains becomes longer, the obtained film exhibits a low birefringence, but the thermal expansion coefficient becomes lower due to the larger free volume. big. [Prior Patent Document] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2013-147599 [Patent Document 2] Japanese Patent Laid-Open No. 2014-114429 [Patent Document 3] International Publication No. 2015/152178 [Non-Patent Document]

[Non-Patent Document 1] Advanced Functional Materials Volume27 Issue2 p.p. 1-7 DOI: 10.1002/adfm.201602969

[Problem to be solved by the invention]

Semi-alicyclic polyimide or full alicyclic polyimide, which are promising substrate materials for flexible displays proposed so far, can be formed with excellent heat resistance, low retardation, excellent flexibility, and excellent transparency. A substrate with excellent performance, but the substrate has a problem of high linear expansion coefficient (>50ppm/°C) or high birefringence (Δn>0.01).

The present invention has been made in view of these circumstances, and an object thereof is to provide a composition for forming a flexible device substrate, which can impart excellent properties of maintaining excellent heat resistance, low retardation, excellent flexibility, and excellent transparency, and in In a film with a thickness of 10nm, it maintains a low coefficient of linear expansion (<50ppm/°C) and a low birefringence (Δn<0.001), which is excellent as a base film for flexible device substrates such as flexible display substrates. Performance resin film. [Means to solve the problem]

As a result of repeated positive examinations by the present inventors in order to achieve the above-mentioned object, it was found that when polyimide is produced from a tetracarboxylic dianhydride component including an alicyclic tetracarboxylic anhydride and a diamine component including an aromatic diamine, it is used as The tetracarboxylic dianhydride component contains alicyclic tetracarboxylic dianhydride with a specific structure and an alicyclic tetracarboxylic dianhydride with a different structure. At the same time, it contains alicyclic tetracarboxylic dianhydride as a diamine component in aromatic diamines. In the case of diamine, when the polyimide obtained by this method is made into a resin film, it can exhibit excellent heat resistance, low retardation, excellent flexibility and excellent transparency, and can be easily peeled off from the glass carrier by the MD method. And complete the present invention.

[式中，B¹ 表示選自下述式(X-1)~(X-11)所成之群之4價基，

(式中，複數的R相互獨立表示氫原子或甲基，*表示鍵結鍵)]，

(式(E1)中，R¹ 分別獨立表示氫原子、鹵原子、苯基或苯基乙基，n表示取代基R¹ 之個數，分別獨立表示0至4之整數)。 　　作為第2觀點，係關於第1觀點之可撓性裝置基板形成用組成物，其中前述二胺成分係對於二胺成分之總莫耳數含有50莫耳%至100莫耳%之式(E1)表示之茀二胺。 　　作為第3觀點，係關於第1觀點或第2觀點之可撓性裝置基板形成用組成物，其中前述四羧酸二酐成分係相對於四羧酸二酐成分之總莫耳數含有20莫耳%至60莫耳%之式(D1)表示之脂環式四羧酸二酐。 　　作為第4觀點，係關於第1觀點至第3觀點中任一者之可撓性裝置基板形成用組成物，其係用於機械剝離法之可撓性裝置之基板形成用組成物。 　　作為第5觀點，係關於一種可撓性裝置基板，係使用第1觀點至第4觀點中任一者之可撓性裝置基板形成用組成物而作成。 　　作為第6觀點，係關於一種可撓性裝置基板之製造方法，其包含 　　將第1觀點至第4觀點中任一者之可撓性裝置基板形成用組成物塗佈於基材，並乾燥、加熱，於基材上形成可撓性裝置基板之步驟，及 　　藉由機械剝離法自前述基材剝離前述可撓性裝置基板之剝離步驟。 [發明效果]That is, in the present invention, as a first viewpoint, it relates to a composition for forming a flexible device substrate, which contains an alicyclic tetracarboxylic dianhydride represented by the following formula (C1) and the following formula ( D1) A polyimide obtained from a tetracarboxylic dianhydride component of an alicyclic tetracarboxylic dianhydride represented by D1 and a diamine component containing stilbene diamine represented by the following formula (E1), and an organic solvent,

[In the formula, B ¹ represents a quaternary group selected from the group formed by the following formulas (X-1)~(X-11),

(wherein, plural Rs independently represent a hydrogen atom or a methyl group, and * represents a bonding bond)],

(In the formula (E1), R ¹ independently represents a hydrogen atom, a halogen atom, a phenyl group or a phenylethyl group, n represents the number of substituent R ¹ , and independently represents an integer from 0 to 4). As a second viewpoint, it relates to the composition for forming a flexible device substrate according to the first viewpoint, wherein the aforementioned diamine component is the formula (E1 ) represents stilbene diamine. As a third viewpoint, it relates to the composition for forming a flexible device substrate according to the first viewpoint or the second viewpoint, wherein the tetracarboxylic dianhydride component contains 20 moles relative to the total moles of the tetracarboxylic dianhydride components. mol% to 60 mol% of the alicyclic tetracarboxylic dianhydride represented by formula (D1). As a fourth viewpoint, it is the composition for forming a flexible device substrate according to any one of the first viewpoint to the third viewpoint, which is a composition for forming a substrate of a flexible device used in a mechanical peeling method. As a fifth viewpoint, it relates to a flexible device substrate produced using the composition for forming a flexible device substrate according to any one of the first viewpoint to the fourth viewpoint. As a sixth aspect, it relates to a method of manufacturing a flexible device substrate, which includes applying the composition for forming a flexible device substrate according to any one of the first to fourth viewpoints on a substrate, drying, heating, forming a flexible device substrate on the substrate, and peeling off the flexible device substrate from the substrate by a mechanical peeling method. [Invention effect]

According to the present invention, it is possible to provide a composition for forming a flexible device substrate, which can impart excellent properties of maintaining excellent heat resistance, low retardation, excellent flexibility and excellent transparency (high light transmittance, low yellowness), Furthermore, it is a resin film having excellent performance as a base film of a flexible device substrate such as a flexible display substrate, which can be easily peeled off from a base material (such as a glass carrier) by an MD method. Moreover, the flexible device substrate of the present invention can maintain the excellent properties of excellent heat resistance, low retardation, excellent flexibility and excellent transparency (high light transmittance, low yellowness), and can be easily fabricated by MD method. The base material (such as a glass carrier) is peeled off, so it can be preferably used as a flexible device, especially a substrate of a flexible display.

[式中，B¹ 表示選自下述式(X-1)~(X-11)所成之群之4價基，

(式中，複數的R相互獨立表示氫原子或甲基，*表示鍵結鍵)]，

(式(E1)中，R¹ 分別獨立表示氫原子、鹵原子、苯基或苯基乙基，n表示取代基R¹ 之個數，分別獨立表示0至4之整數)。Hereinafter, the present invention will be described in detail. The composition for forming the flexible device substrate of the present invention contains tetracarboxylic acid dianhydrides represented by the following formula (C1) and alicyclic tetracarboxylic dianhydrides represented by the following formula (D1). A polyimide obtained from a carboxylic dianhydride component and a diamine component containing stilbene diamine represented by the following formula (E1), and an organic solvent.

[In the formula, B ¹ represents a quaternary group selected from the group formed by the following formulas (X-1)~(X-11),

(wherein, plural Rs independently represent a hydrogen atom or a methyl group, and * represents a bonding bond)],

(In the formula (E1), R ¹ independently represents a hydrogen atom, a halogen atom, a phenyl group or a phenylethyl group, n represents the number of substituent R ¹ , and independently represents an integer from 0 to 4).

[Polyimide] The polyimide used in the present invention is a polyimide having an alicyclic skeleton in the main chain. Specifically, the aforementioned polyimide is a tetracarboxylic dianhydride component containing the alicyclic tetracarboxylic dianhydride represented by the aforementioned formula (C1) and the aforementioned alicyclic tetracarboxylic dianhydride represented by the aforementioned formula (D1). A polyimide obtained by imidizing polyamic acid obtained by reacting with a diamine component including stilbene diamine represented by the aforementioned formula (E1). That is to say, the above-mentioned polyimide is preferably an imide compound of polyamic acid, and the polyamic acid is an alicyclic tetracarboxylic dianhydride represented by the aforementioned formula (C1) and an alicyclic tetracarboxylic dianhydride represented by the aforementioned formula (D1). The reaction product of the tetracarboxylic dianhydride component of the alicyclic tetracarboxylic dianhydride and the diamine component containing the stilbene diamine represented by said formula (E1).

[式中，B¹ 表示選自下述式(X-1)~(X-11)所成之群之4價基，

(式中，複數的R相互獨立表示氫原子或甲基，*表示鍵結鍵)]。

[In the formula, B ¹ represents a quaternary group selected from the group formed by the following formulas (X-1)~(X-11),

(In the formula, plural Rs independently represent a hydrogen atom or a methyl group, and * represents a bonding bond)].

Among the alicyclic tetracarboxylic dianhydrides represented by the above formula (C1), compounds represented by the formulas (X-1), (X-4), and (X-7) are preferable for B ¹ in the formula. As a preferred example, the alicyclic tetracarboxylic dianhydride represented by the above formula (C1) and the alicyclic tetracarboxylic dianhydride represented by the above formula (D1) are reacted with the stilbene diamine represented by the above formula (E1) The polyimide obtained by imidizing the obtained polyamic acid contains monomer units represented by the following formulas (1) and (1′).

In order to obtain the object of the present invention, it maintains the excellent performance of excellent heat resistance, low retardation, excellent flexibility and excellent transparency, and is suitable for flexible devices that can be easily peeled off from the substrate (such as glass carrier) by MD method For the resin film on the substrate, the alicyclic tetracarboxylic dianhydride represented by the above formula (C1) is preferably at least 40 mole % and at least 90 mole % relative to the total molar number of tetracarboxylic dianhydride components, and more preferably It is preferably at least 40 mol% but not more than 80 mol%, more preferably at least 60 mol% and not more than 80 mol%, and it is represented by formula (D1) relative to the total molar number of tetracarboxylic dianhydride components The alicyclic tetracarboxylic dianhydride is preferably from 10 mol% to 60 mol%, more preferably from 20 mol% to 60 mol%, more preferably from 20 mol% to 40 mol%. . And similarly, in order to obtain the excellent performance of maintaining excellent heat resistance, low retardation, excellent flexibility and excellent transparency, and can be easily peeled off from the substrate (such as glass carrier) by MD method, it is suitable for flexible devices In the resin film of the substrate, the diamine represented by the above formula (E1) is 50 mol % or more, for example, preferably 50 mol % or more and 100 mol % or less, with respect to the total molar number of diamine components, more preferably It is more than 70 mol%, more preferably more than 95 mol%.

(式(1)中，B¹ 表示選自上述式(X-1)~(X-11)所成之群之4價基，R¹ 分別獨立表示氫原子、鹵原子、苯基或苯基乙基，n表示取代基R¹ 之個數，分別獨立表示0至4之整數)。

(式(1’)中，R¹ 分別獨立表示氫原子、鹵原子、苯基或苯基乙基，n表示取代基R¹ 之個數，分別獨立表示0至4之整數)。As an example of a preferable aspect, the polyimide used in this invention contains the monomer unit represented by following formula (1) and the monomer unit represented by following formula (1').

(In formula (1), B ¹ represents a quaternary group selected from the group formed by the above formulas (X-1)~(X-11), and R ¹ independently represents a hydrogen atom, a halogen atom, a phenyl group or a phenyl group Ethyl, n represents the number of substituent R ¹ , each independently represents an integer of 0 to 4).

(In formula (1'), R ¹ independently represents a hydrogen atom, a halogen atom, a phenyl group or a phenylethyl group, n represents the number of substituent R ¹ , and independently represents an integer from 0 to 4).

(式(1-1)中，複數的R相互獨立表示氫原子或甲基)。The monomer unit represented by the above formula (1) is preferably represented by the formula (1-1).

(In the formula (1-1), plural Rs independently represent a hydrogen atom or a methyl group).

As a monomer unit represented by said formula (1'), what is represented by a formula (1'-1) is preferable.

(Synthesis of polyamic acid) The polyimide used in the present invention, as mentioned above, is made to include the alicyclic tetracarboxylic dianhydride represented by the above formula (C1) and the alicyclic tetracarboxylic dianhydride represented by the above formula (D1). The polyamic acid obtained by reacting the tetracarboxylic dianhydride component of a carboxylic dianhydride with the diamine component containing the stilbene diamine represented by said formula (E1) is obtained by imidating. The reaction from the above components to polyamic acid can be carried out relatively easily in an organic solvent, and it is advantageous in terms of not forming by-products.

The feeding ratio (molar ratio) of the diamine component in the reaction between the tetracarboxylic dianhydride component and the diamine component is based on consideration of polyamic acid, or even polyimide obtained by subsequent imidization. The molecular weight of the amine is appropriately set, but for the tetracarboxylic dianhydride component 1, usually the diamine component can be set to about 0.8 to 1.2, for example, about 0.9 to 1.1, preferably about 0.98 to 1.02. Similar to the usual polycondensation reaction, the closer the molar ratio is to 1.0, the larger the molecular weight of the polyamic acid produced.

The organic solvent used for the reaction of the tetracarboxylic dianhydride component and the diamine component is not particularly limited as long as it does not adversely affect the reaction and can dissolve the produced polyamic acid. Specific examples thereof are listed below. Examples are, for example, m-cresol, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, N,N-dimethylformamide, N,N-Dimethylacetamide, 3-Methoxy-N,N-Dimethylpropionamide, 3-Ethoxy-N,N-Dimethylpropionamide, 3-Propoxy -N,N-Dimethylpropionamide, 3-isopropoxy-N,N-dimethylpropionamide, 3-butoxy-N,N-dimethylpropionamide, 3-th Tributoxy-N,N-dimethylpropionamide, 3-tertiary butoxy-N,N-dimethylpropionamide, γ-butyrolactone, N-methylcaprolactone, di Methylphenoxide, Tetramethylurea, Pyridine, Dimethylsulfone, Hexamethylsulfoxide, Isopropanol, Methoxymethylpentanol, Dipentene, Ethyl Amyl Ketone, Methyl Nonyl Ketone , Methyl Ethyl Ketone, Methyl Isoamyl Ketone, Methyl Isopropyl Ketone, Methyl Cellosolve, Ethyl Cellosolve, Methyl Cellosolve Acetate, Ethyl Cellosolve Acetate , Butyl Carbitol, Ethyl Carbitol, Ethylene Glycol, Ethylene Glycol Monoacetate, Ethylene Glycol Monoisopropyl Ether, Ethylene Glycol Monobutyl Ether, Propylene Glycol, Propylene Glycol Monoacetate, Propylene Glycol Mono Methyl ether, propylene glycol tertiary butyl ether, dipropylene glycol monomethyl ether, diethylene glycol, diethylene glycol monoacetate, diethylene glycol dimethyl ether, dipropylene glycol monoacetate monomethyl ether, dipropylene glycol monomethyl ether Methyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monoacetate monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monoacetate monopropyl ether, 3-methyl-3-methoxybutyl acetate, three Propylene glycol methyl ether, 3-methyl-3-methoxybutanol, diisopropyl ether, ethyl isobutyl ether, diisobutylene, amyl acetate, butyl butyrate, butyl ether, diisobutyl ketone, methyl Cyclohexene, propyl ether, dihexyl ether, dioxane, n-hexane, n-pentane, n-octane, diethyl ether, cyclohexanone, ethylene carbonate, propylene carbonate, methyl lactate, ethyl lactate Esters, methyl acetate, ethyl acetate, n-butyl acetate, propylene glycol monoethyl ether, methyl pyruvate, ethyl pyruvate, methyl 3-methoxypropionate, isopropyl 3-ethoxypropionate , 3-methoxy ethyl propionate, 3-ethoxy propionate, 3-methoxy propionate, 3-methoxy propyl propionate, 3-methoxy butyl propionate, diethylene di Alcohol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, etc., but not limited thereto. These can be used individually or in combination of 2 or more types. Furthermore, even if it is a solvent that does not dissolve polyamic acid, it can also be used by mixing with the above-mentioned solvents within the range that does not precipitate the produced polyamic acid. Moreover, the moisture in the organic solvent hinders the polymerization reaction and becomes the cause of the hydrolysis of the generated polyamic acid, so it is preferable to use the organic solvent that is dehydrated and dried as much as possible.

As a reaction method of the above-mentioned tetracarboxylic dianhydride component and diamine component in an organic solvent, for example, the dispersion liquid or solution obtained by dispersing or dissolving the diamine component in an organic solvent is stirred, and the tetracarboxylic acid diamine component is directly added therein. An anhydride component, or a method of adding the component by dispersing or dissolving it in an organic solvent, on the contrary, a method of adding a diamine component to a dispersion or solution obtained by dispersing or dissolving the tetracarboxylic dianhydride component in an organic solvent , and there is a method of alternately adding a tetracarboxylic dianhydride component and a diamine compound component, etc., and any of these methods may be used. Moreover, when the tetracarboxylic dianhydride component and/or the diamine component are composed of multiple compounds, they can be reacted in a pre-mixed state, or they can be individually reacted sequentially, and then the individually reacted low-molecular-weight bodies are mixed and reacted to form high-molecular-weight compounds. .

The temperature during the synthesis of the above-mentioned polyamic acid can be appropriately set within the range from the melting point to the boiling point of the solvent used above. For example, any temperature can be selected from -20°C to 150°C, but it is preferably -5°C to 150°C, usually About 0°C~150°C, preferably about 0°C~140°C. The reaction time cannot be generalized because it depends on the reaction temperature or the reactivity of the raw materials, but it is usually about 1 to 100 hours. Again, although the reaction can be carried out at any concentration, when the concentration is too low, it is difficult to obtain a high molecular weight polymer. The total concentration in the reaction solution is preferably from 1 to 50% by mass, more preferably from 5 to 40% by mass. It can also be carried out at a high concentration in the initial stage of the reaction, and an organic solvent is added thereafter.

(Imidation of polyamic acid) Examples of methods for imidizing polyamic acid include thermal imidization by directly heating a polyamic acid solution, and adding a catalyst to a polyamic acid solution. Catalytic imidization. The temperature for thermal imidization of polyamic acid in the solution is 100°C~400°C, preferably 120°C~250°C, preferably while removing the water generated by the imidization reaction to the outside of the system conduct.

The chemical (catalyst) imidization of polyamic acid can be achieved by adding an alkaline catalyst to the polyamic acid solution, stirring the system at a temperature of -20°C~250°C, preferably 0°C~180°C And proceed. The amount of the alkaline catalyst is 0.5-30 mole times, preferably 1.5-20 mole times of the amide acid group of polyamic acid.

As the basic catalyst, it can be exemplified by pyridine, triethylamine, trimethylamine, tributylamine, trioctylamine, 1-ethylpiperidine, etc., wherein pyridine and 1-ethylpiperidine have a suitable base for the reaction Sex is better. The imidization rate of catalytic imidization can be controlled by adjusting the amount of catalyst, reaction temperature and reaction time.

In the polyimide resin used in the present invention, the dehydration ring-closing rate (imidization rate) of the amide acid group does not necessarily have to be 100%, and it can be adjusted arbitrarily according to the application or purpose. The best is more than 50%.

In the present invention, after filtering the above-mentioned reaction solution, the filtrate can be used as it is, or can be diluted or concentrated to prepare a composition for forming a flexible device substrate. Further, other components (organic or inorganic low-molecular or high-molecular compounds) and the like described later may be blended therein to prepare a composition for forming a flexible device substrate. When filtered in this way, not only can the contamination of impurities that may cause deterioration of the heat resistance, flexibility, or linear expansion coefficient characteristics of the resin film obtained from the composition be reduced, but also the composition for forming flexible device substrates can be obtained efficiently. things.

In addition, the polyimide used in the present invention is determined by gel permeation chromatography (GPC) in consideration of the strength of the resin film obtained from the aforementioned composition, the workability of the resin film, and the uniformity of the resin film. The weight average molecular weight (Mw) in terms of polystyrene is preferably from 5,000 to 350,000.

(Polymer recovery) To recover and use the polymer component from the reaction solution of polyamic acid and polyimide, it is enough to put the reaction solution into a weak solvent to precipitate it. Examples of poor solvents used for precipitation include methanol, acetone, hexane, butyl cellosolve, pentane, methyl ethyl ketone, methyl isobutyl ketone, ethanol, toluene, benzene, water, and the like. The polymer precipitated by throwing in a weak solvent can be dried under normal pressure or reduced pressure, at normal temperature or by heating after being recovered by filtration. Moreover, when the polymer recovered by precipitation is re-dissolved in an organic solvent and recovered for re-precipitation for 2 to 10 times, the impurities in the polymer can be reduced. In this case, when three or more types of weak solvents such as alcohols, ketones, and hydrocarbons are used as the weak solvent, it is preferable because the efficiency of purification can be further improved.

The organic solvent for dissolving the resin component in the reprecipitation recovery step is not particularly limited. Specific examples include N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, 2-pyrrolidone, N -Ethyl-2-pyrrolidone, N-vinylpyrrolidone, dimethyl urea, tetramethyl urea, pyridine, dimethyl urea, hexamethyl urea, γ-butyrolactone, 1,3-dimethyl Base-2-imidazolidinone, dipentene, ethyl amyl ketone, methyl nonyl ketone, methyl ethyl ketone, methyl isoamyl ketone, methyl isopropyl ketone, cyclohexanone, biscarbonate Ethyl ester, propylene carbonate, diethylene glycol dimethyl ether, 4-hydroxy-4-methyl-2-pentanone, etc. These solvents can also be used in mixture of 2 or more types.

[Organic solvent] The composition for forming a flexible device substrate of the present invention contains an organic solvent in addition to the aforementioned polyimide. The organic solvent is not particularly limited, and examples thereof include the same ones as the specific examples of the reaction solvent used in the preparation of the above-mentioned polyamic acid and polyimide. More specifically, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidine are exemplified Ketone, N-ethyl-2-pyrrolidone, γ-butyrolactone, etc. Moreover, an organic solvent may be used individually by 1 type, and may use it in combination of 2 or more types. Among them, N,N-dimethylacetamide, N-methyl-2- Pyrrolidone, gamma-butyrolactone.

[Composition for forming flexible device substrate] The present invention is a composition for forming a flexible device substrate containing the aforementioned polyimide and an organic solvent. Here, the composition for forming the flexible device substrate of the present invention is uniform, and no phase separation is observed. Furthermore, the solid content in the flexible device substrate forming composition of the present invention is usually in the range of 0.5 to 30% by mass, but from the viewpoint of film uniformity, it is preferably at least 5% by mass and at most 20% by mass. In addition, the term "solid content" refers to the remaining components after removing the solvent from all the components constituting the composition for forming a flexible device substrate. Also, the viscosity of the flexible device substrate forming composition may be appropriately determined in consideration of the coating method used, the thickness of the resin film to be produced, etc., but it is usually 1 to 50,000 mPa·s at 25°C.

In the flexible device substrate forming composition of the present invention, various other organic or inorganic low-molecular or high-molecular compounds may be blended in order to impart processability or various functionalities. For example, catalysts, defoamers, leveling agents, surfactants, dyes, plasticizers, fine particles, coupling agents, sensitizers, etc. can be used. For example, a catalyst may be added for the purpose of reducing the retardation or linear expansion coefficient of a resin film obtained from the composition.

[Flexible Device Substrate] By applying the composition for forming a flexible device substrate of the present invention described above to a substrate, drying, and heating to remove the solvent, it is possible to obtain a substrate that can maintain excellent heat resistance, low retardation, and excellent flexibility. Furthermore, it is a resin film that has excellent properties of excellent transparency and can be easily peeled off from a substrate (such as a glass carrier) by the MD method, that is, a flexible device substrate. A flexible device substrate made of the composition for forming a flexible device substrate of the present invention is also an object of the present invention.

As substrates used in the manufacture of flexible device substrates (resin films), for example, plastics (polycarbonate, polymethacrylate, polystyrene, polyester, polyolefin, epoxy resin, melamine, triethylene Acyl cellulose, ABS, AS, norbornene-based resin, etc.), metal, stainless steel (SUS), wood, paper, glass, silicon wafer, slate, etc. In particular, when used as a flexible device substrate, based on the viewpoint that existing equipment can be utilized, the substrate used is preferably glass or a silicon wafer, and based on the obtained flexible device substrate showing good peelability, more preferably Glass. Also, the coefficient of linear expansion of the substrate to be used is preferably at most 40 ppm/°C, more preferably at most 30 ppm/°C, from the viewpoint of warpage of the substrate after coating.

The method of coating the substrate with the composition for forming a flexible device substrate is not particularly limited, but examples thereof include cast coating, spin coating, blade coating, dip coating, and roll coating. , bar coating method, die coating method, inkjet method, printing method (letterpress, gravure, lithography, screen printing, etc.), etc., can be used appropriately according to the purpose.

The heating temperature is preferably at most 300°C. When the temperature exceeds 300° C., the obtained resin film may become brittle, and in particular, a resin film suitable for use as a display substrate may not be obtained. Moreover, when considering the heat resistance and linear expansion coefficient characteristics of the obtained resin film, it is desirable to directly increase the heating temperature step by step after heating the coated flexible device substrate forming composition at 40°C~100°C for 5 minutes~2 hours , and finally heated at over 175°C~280°C for 30 minutes~2 hours. In this way, by heating at two or more stages of the stage of drying the solvent and the stage of promoting molecular alignment, low thermal expansion characteristics can be exhibited more reproducibly. In particular, it is preferable to heat the coated flexible device substrate-forming composition at 40° C. to 100° C. for 5 minutes to 2 hours, then heat it at over 100° C. to 175° C. for 5 minutes to 2 hours, and then, heat it at more than 175° C. ℃~280℃ heating for 5 minutes to 2 hours. Examples of appliances used for heating are heating plates, ovens, etc. The heating environment can be under air or inert gas such as nitrogen, and can be under normal pressure or reduced pressure, and different pressures can be applied in each stage of heating.

The thickness of the resin film can be appropriately determined in the range of 1-200 μm considering the type of flexible device, but especially when it is assumed to be used as a substrate for a flexible display, it is usually about 1-60 μm, preferably about 5-50 μm , and adjust the thickness of the coating film before heating to form a resin film of desired thickness. Also, the method of peeling the resin film formed in this way from the substrate is not particularly limited, and examples thereof include a method of cooling the resin film together with the substrate, cutting the film and peeling it, or a method of peeling it by applying tension through a roller. Wait.

Furthermore, the resin film has a coefficient of linear expansion at, for example, 50°C to 200°C of 50 ppm/°C or less, especially a relatively low value of 45 ppm/°C to 49 ppm/°C, and is excellent in dimensional stability when heated. The advantage of this resin film is that the in-plane retardation R0 expressed by the product of the birefringence (difference between two orthogonal refractive indices in the plane) and the film thickness when the wavelength of the incident light is set to _590nm and the self-thickness Retardation in the thickness direction R _th represented by the average value of the two phase differences obtained by multiplying the two birefringences (the difference between the two refractive indices in the plane and the refractive index in the thickness direction) when observing the cross-section in the same direction by the film thickness Both are small. When the average film thickness of the resin film is about 10 μm, the _retardation R in the thickness direction is less than 10 nm (for example, less than 6 nm), the in-plane retardation R is less than ₅ nm (for example, less than 1 nm), and the birefringence Δn is less than 0.001 (for example, less than 0.0004).

The resin film described above has the above-mentioned characteristics, so it satisfies the various conditions necessary for the base film of the substrate of the flexible device, and can be preferably used as the base film of the substrate of the flexible device, especially the flexible display. . [Example]

The following examples are given to describe the present invention more specifically, but the present invention is not limited to the following examples.

The abbreviations used in the following examples have the following meanings. <Acid dianhydride> BODAxx: Bicyclo[2,2,2]octane-2,3,5,6-tetracarboxylic dianhydride CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride BODA : Bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride <diamine> FDA: 9,9'-bis(4-aminophenyl) fluorine< Organic solvents > GBL: γ-butyrolactone

In addition, in the examples, the equipment and conditions used for the preparation of the samples and the analysis and evaluation of the physical properties are as follows. 1) Determination of number average molecular weight and weight average molecular weight The number average molecular weight (hereinafter referred to as Mn) and weight average molecular weight (hereinafter referred to as Mw) of polymers are based on the device: Showdex GPC-101 made by Showa Denko Co., Ltd., column: KD803 and KD805, column temperature: 50°C, dissolution solvent: DMF, flow rate: 1.0ml/min, calibration line: standard polystyrene conditions for determination. 2) Coefficient of linear expansion (CTE), glass transition temperature (Tg) Use TMA Q400 manufactured by TA Instruments to measure the size of the resin film cut into a width of 5mm and a length of 16mm. First, heat up to 50 or even 350°C at 10°C/min (First heating), secondly, after cooling down to 50°C at 10°C/min, and heating at 10°C/min to 50 or even 420°C (second heating), linear expansion at 50°C or even 250°C during the second heating Calculate the value of the coefficient (CTE [ppm/°C]). Also, a load of 0.05 N was applied through the first heating, cooling, and second heating. The value of the glass transition temperature (Tg) was calculated from the start point of the rapid dimensional change near the end of the second heating. 3) 5% weight loss temperature (Td _5% ) 5% weight loss temperature (Td _5% [°C]) uses TGA Q500 manufactured by TA Instruments, and heats up about 5 to 10 mg of resin film at 10°C/min in nitrogen atmosphere It is obtained by heating to 50 or even 800°C and measuring. 4) Light transmittance (transparency) (T _308nm , T _400nm , T _550nm ) and CIE b value (CIE b*) Use Nippon Denshoku Industry Co., Ltd. SA4000 spectrometer at room temperature, the reference is set to air Determination of light transmittance (T _308nm , T _400nm , T _550nm [%]) and CIE b value (CIE b*) at wavelengths of 308nm, 400nm and 550nm. 5) Retardation (R _th , R ₀ ) Retardation in the thickness direction (R _th ) and in-plane retardation (R ₀ ) were measured at room temperature using KOBURA 2100ADH manufactured by Oji Scientific Instruments. In addition, thickness-direction retardation (R _th ) and in-plane retardation (R ₀ ) were calculated by the following formulas. R ₀ =(Nx-Ny)×d=ΔNxy×d R _th =[(Nx+Ny)/2-Nz]×d=[(ΔNxz×d)+(ΔNyz×d)/2 Nx, Ny: surface Inner orthogonal 2 refractive indices (Nx>Ny, Nx is also called the slow axis, Ny is also called the fast axis) Nz: Refractive index for the surface thickness (vertical) direction d: Film thickness ΔNxy: 2 in-plane Refractive index difference (Nx－Ny) (birefringence) ΔNxz: The difference between the in-plane refractive index Nx and the thickness direction Nz (birefringence) ΔNyz: The in-plane refractive index Ny and the thickness direction Nz difference ( Birefringence) 6) Birefringence (Δn) was calculated by the following formula using the value of retardation in the thickness direction (R _th ) obtained from <6) Retardation> above. Δn =[R _th /d (film thickness)]/1000 7) Film thickness The film thickness of the obtained resin film was measured with a thickness gauge manufactured by TECLOCK Co., Ltd.

[1] Synthesis sequence of polyimide (example of Synthesis Example 2 below) In a 200mL tank equipped with nitrogen gas injection port/exhaust port, Ding Stark trap, mechanical stirrer and condenser (water cooler) 6.272 g (0.018 mol) of FDA was put into the neck flask, and 20.57 g of GBL was added immediately thereafter, and stirring was started. After the diamine was completely dissolved in the solvent, while stirring the solution, BODAxx 2.251g (0.009mol) and CBDA 1.765g (0.009mol) were added sequentially, GBL 20.58g was added, and the temperature was raised to 140°C under a nitrogen atmosphere. Next, 0.41 g of 1-ethylpiperidine was added to the system, and heated to an internal temperature of 180°C within 7 hours under nitrogen. After stopping the heating, GBL was added to the reaction system, the solution was diluted to 6% by mass, and stirred overnight. The next day, the polyimide reaction solution was added dropwise to 600 ml of methanol, stirred for 30 minutes, and the solid polyimide was recovered by filtration. This sequence was repeated 3 times. The methanol residue in the polyimide was removed by drying in a vacuum oven at 150° C. and -100 kPa for 8 hours, and finally obtained 9.42 g of dry polyimide 2 . The mass percentage yield of polyimide was 98%, Mw=154,096, Mn=41,946.

The synthesis reaction scheme of polyimides 1-5 is as follows.

[Synthesis Example 1] According to the above synthesis sequence, the P1 polymer was synthesized: CBDA/BODAxx/FDA=40/60/100 (molar ratio), and 7.54 g of dried polyimide 1 was obtained. The mass percent yield of polyimide is 77%, and Mw and Mn are as recorded in Table 1. [Synthesis Example 2] According to the above-mentioned synthesis sequence, the P2 polymer was synthesized: CBDA/BODAxx/FDA=50/50/100 (molar ratio), and 9.42 g of dried polyimide 2 were obtained. The mass percentage yield of polyimide is 98%, and Mw and Mn are as recorded in Table 1. [Synthesis Example 3] According to the above synthesis sequence, the P3 polymer was synthesized: CBDA/BODAxx/FDA=60/40/100 (molar ratio), and 7.39 g of dried polyimide 3 was obtained. The mass percent yield of polyimide is 77%, and Mw and Mn are as recorded in Table 1. [Synthesis Example 4] According to the above synthesis sequence, the P4 polymer was synthesized: CBDA/BODAxx/FDA=70/30/100 (molar ratio), and 7.95 g of dried polyimide 4 was obtained. The mass percentage yield of polyimide is 84%, and Mw and Mn are as recorded in Table 1. [Synthesis Example 5] According to the above synthesis sequence, a P5 polymer was synthesized: CBDA/BODAxx/FDA=80/20/100 (molar ratio), and 6.68 g of dried polyimide 5 was obtained. The mass percentage yield of polyimide is 71%, and Mw and Mn are as recorded in Table 1. [Comparative Example 1] The PC1 polymer having BODA/FDA=100/100 (molar ratio) as Comparative Example 1 is the polymer described in Example No. 1a of International Publication No. 2013/170135 specification. [Comparative Example 2] As Comparative Example 2, CBDA and FDA were synthesized according to the above-mentioned synthesis procedure with CBDA/FDA=100/100 (molar ratio), but gelation occurred during the synthesis, and a polymer could not be obtained. [Comparative Example 3] As Comparative Example 3, BODAxx and FDA were synthesized according to the above-mentioned synthesis procedure at BODAxx/FD=100/100 (molar ratio). 9.57 g of the PC3 polymer was obtained, but a film could not be formed.

[2] Preparation example of polyimide solution (paint) The polyimide obtained in the above synthesis examples was dissolved in GBL solvent at room temperature to 12% by mass.

[3] Film formation example The polyimide solutions (paints) obtained in the above [2] were slowly filtered through a 25 μm filter under pressure, and the resulting solution was coated on a glass substrate, and in an air environment, at 80 ℃ for 60 minutes, 140 ℃ for 30 minutes, then 200 ℃ for 60 minutes, then in the air at 240 ℃ for 60 minutes to obtain the polyimide films of Examples 1 to 5 (resin film). The obtained resin film was cut into rectangles and peeled off for evaluation.

[4] Evaluation of Resin Films The resin films of Examples 1 to 5 produced in the above procedure were peeled off by mechanical cutting, and then used for evaluation. Regarding the thermal and optical properties of each resin film, that is, the coefficient of linear expansion (50~200°C: CTE[ppm/°C]), 200~250°C: CTE[ppm/°C], glass transition temperature (Tg[°C] ), 5% weight reduction temperature (Td _5% [°C]), light transmittance (T _308nm [%], T _400nm [%], T _550nm [%]) and CIE b value (yellow evaluation: CIE b*) , retardation (R _th [nm], R ₀ [nm]), and birefringence (Δn) were evaluated in the order described above. The results are shown in Table 1.

As shown in Table 1, it is confirmed that the resin films of Examples 1 to 5 have a low coefficient of linear expansion [ppm/°C] and a high light transmittance [%] at 400nm and 550nm after curing, and the yellow color represented by CIE b* value When the degree is small, the retardation R _th , R ₀ and secondary refractive index all become lower values. Moreover, the resin films obtained in Examples 1 to 5 mentioned above will not crack when held with both hands and bent into an acute angle (about 30 degrees), and have the high flexibility required by flexible display substrates.

Claims (6)

A composition for forming a flexible device substrate, which contains tetracarboxylic acid dianhydrides represented by the following formula (C1) and alicyclic tetracarboxylic dianhydrides represented by the following formula (D1). A polyimide obtained from a carboxylic dianhydride component and a diamine component containing stilbene diamine represented by the following formula (E1), and an organic solvent,

[In the formula, B ¹ represents a quaternary group selected from the group formed by the following formulas (X-1)~(X-11),

(wherein, plural Rs independently represent a hydrogen atom or a methyl group, and * represents a bonding bond)],

(In the formula (E1), R ¹ independently represents a hydrogen atom, a halogen atom, a phenyl group or a phenylethyl group, n represents the number of substituent R ¹ , and independently represents an integer from 0 to 4). The composition for forming flexible device substrates as claimed in claim 1, wherein the aforementioned diamine component contains 50 mol % to 100 mol % of stilbene diamine represented by formula (E1) with respect to the total moles of diamine components . The composition for forming flexible device substrates according to claim 1 or 2, wherein the aforementioned tetracarboxylic dianhydride component contains 20 mol% to 60 mol% of the total molar number of tetracarboxylic dianhydride components Alicyclic tetracarboxylic dianhydride represented by formula (D1). The composition for forming a substrate of a flexible device according to claim 1 or 2, which is a composition for forming a substrate of a flexible device used in a mechanical peeling method. A flexible device substrate made using the composition for forming a flexible device substrate according to any one of Claims 1 to 4. A method for manufacturing a flexible device substrate, comprising applying the composition for forming a flexible device substrate according to any one of claims 1 to 4 on a substrate, drying, and heating to form a flexible device substrate on the substrate. Step of flexible device substrate, and peeling the aforementioned flexible device substrate from the aforementioned base material by a mechanical peeling method The stripping step.