KR20180018392A - Polyimide precursor, polyimide and manufacturing method of transparent polyimide film - Google Patents

Abstract

The present invention relates to a polyimide precursor which comprises a structural unit derived from diamine, and a structure unit derived from acid dianhydride. The light transmittance is less than or equal to 5% at 308 nm, and is greater than or equal to 70% at 400 nm, and a thermal expansion coefficient is less than or equal to 45 ppm/k when polyimide is prepared through imidization. The dimensional stability, transparency, and heat resistance are excellent.

Description

TECHNICAL FIELD [0001] The present invention relates to a polyimide precursor, a polyimide precursor, a polyimide precursor, and a method for producing a transparent polyimide film,

INDUSTRIAL APPLICABILITY The present invention is useful as a transparent film material (transparent film material) or a transparent flexible substrate material (transparent flexible substrate material), and is particularly excellent in transparency (high transparency), low thermal expansion coefficient (low thermal expansion coefficient), high heat resistance (Laser lift-off characteristics), and a precursor thereof, which are useful as a transparent resin substrate material. The present invention also relates to a process for producing a transparent polyimide film, particularly a process for producing a transparent polyimide film useful as a resin substrate material having high transparency, low thermal expansion coefficient, high heat resistance and laser lift-off characteristics.

There has been a tendency that the performance of electronic devices is rapidly progressed, and that there is a tendency to increase in weight and thickness, and accordingly, there is an increasing demand for high performance for components used in electronic equipment and substrates mounted thereon. A glass substrate is used as a substrate of a display panel in a display, and in particular, in the use of a touch panel. However, a reduction in the processing cost by a roll-to-roll process and a thinner, lighter, A resin substrate material has been developed. However, since resins generally have inferior dimensional stability, transparency and heat resistance as compared with glass, various investigations have been made.

Examples of the display include a large display such as a television, and a small display such as a cellular phone, a PC, and a smart phone. For example, as a supporting substrate on which various elements such as a thin film transistor (TFT) , And glass substrates are used. In addition, in the use of the touch panel, similarly, there is a strong demand for a resin substrate material capable of replacing a glass substrate, and in this case, a low coefficient of thermal expansion (CTE) is required. For example, And so on.

As such a resin substrate material, polyimide is one of promising materials because of its excellent heat resistance and dimensional stability.

In recent years, in order to obtain a thin polyimide substrate, a polyimide film is formed on a supporting substrate having one end with a glass substrate as a supporting substrate, and then an electronic component is mounted thereon. It has also been proposed to peel off. For example, Patent Document 1 discloses a polyimide precursor resin composition for forming a flexible device substrate which is produced by peeling from a carrier substrate, and has a glass transition temperature of 300 占 폚 or higher and a thermal expansion coefficient of 20 ppm / K or lower. However, there is no review on transparency. Patent Document 2 discloses a laminate comprising a polyimide film obtained by casting a polyimide precursor solution having a specific structure on an inorganic substrate, followed by drying and imidization, and a laminate comprising an inorganic substrate, which has high light transmittance and high outgas, . However, since the coefficient of thermal expansion (CTE) of polyimide exceeds 45 ppm / K, the difference from the thermal expansion coefficient of 10 ppm / K or less of the glass substrate is large, which is inferior in shape stability.

Patent Document 3 discloses that the transmittance of a diamine or tetracarboxylic dianhydride used as a raw material to control the transmittance strictly in order to reduce the coloring of the polyimide. Patent Document 4 discloses a process for producing a polyimide film of colorless transparent and low CTE by specifying a structure derived from a diamine and a structure derived from a tetracarboxylic acid dianhydride and synthesizing an amide derived from a specific alicyclic tetracarboxylic dianhydride Discloses a polyimide precursor and a resin composition having an imidization ratio of 10 to 100%. In addition, Patent Document 5 discloses that a diamine compound and a compound containing three or more amino groups are reacted with a tetracarboxylic dianhydride, and Patent Document 6 discloses a method in which a polymer solution containing fine particles in a polyimide- Containing layer is formed.

However, it is still expected that a practical heat-resistant transparent resin substrate material that can substitute for a glass substrate and satisfy required characteristics such as dimensional stability, and a method for manufacturing a transparent polyimide film useful as a material for a heat- This is the current situation.

Japanese Patent Application Laid-Open No. 2010-202729 Japanese Unexamined Patent Application Publication No. 2012-40836 Japanese Patent Application Laid-Open No. 2013-23583 International Patent Publication No. 2015/122032 Japanese Unexamined Patent Application Publication No. 2014-210896 Japanese Patent Application Laid-Open No. 2013-209498

The present invention relates to a polyimide precursor and polyimide useful as a heat resistant transparent resin substrate material which is excellent in dimensional stability, transparency and heat resistance under such a background and can be easily peeled off from a supporting substrate to obtain a thin polyimide film, It is another object of the present invention to provide a method for producing a transparent polyimide film useful as a material.

The present invention relates to a polyimide precursor comprising a structural unit derived from a diamine and a structural unit derived from an acid dianhydride, wherein the polyimide precursor is 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl ( (Trifluoromethyl) benzidine) and a structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride, and the structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride and the structural unit derived from 1,2,3,4- A structural unit derived from 3,4-cyclobutanetetracarboxylic dianhydride is contained in an amount of 70 mol% or more of the structural units derived from the total acid dianhydride, and the light transmittance when imidized into polyimide is 30% Or less, and is at least 70% at 400 nm, and has a thermal expansion coefficient of 45 ppm / K or less.

The polyimide precursor preferably satisfies any one or more of the following.

1) A polymer comprising 50 mol% or more of the structural units derived from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl in the structural units derived from all diamines.

2) a copolymer containing a structural unit derived from a diamine other than 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl in an amount of less than 50 mol% in the structural units derived from the whole diamine, Containing less than 30 mol% of structural units derived from acid dianhydrides other than 2,3,4-cyclobutanetetracarboxylic dianhydride in the structural units derived from all acid dianhydrides.

3) the structural unit derived from an acid dianhydride is a structural unit derived from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, a structural unit derived from pyromellitic anhydride, or a structural unit derived from 2,2'- Further comprising a structural unit derived from bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride.

4) The structural unit derived from a diamine further contains a structural unit derived from 2,2'-dimethyl-4,4'-diaminobiphenyl.

The present invention also provides a polyimide comprising a structural unit derived from a diamine and a structural unit derived from an acid dianhydride, wherein the polyimide is selected from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl And a structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic acid dianhydride and having a structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride as a whole A polyimide comprising 70 mol% or more of the structural units derived from acid dianhydride and a polyimide having a light transmittance of 5% or less at 308 nm, 70% or more at 400 nm and a thermal expansion coefficient of 45 ppm / K or less .

The polyimide preferably has a yellowness degree of 6 or less. The polyimide is excellent as a material for a transparent resin substrate.

The present invention also provides a process for producing a polyimide precursor, comprising the steps of: applying a polyimide precursor or its resin solution onto the surface of a support; heating the polyimide precursor or the resin solution to imidize and forming a polyimide layer on the surface of the support; And a step of peeling the polyimide layer from the support to obtain a polyimide film, wherein the polyimide precursor is at least one selected from the group consisting of 2,2'-bis (trifluoromethyl) -4, Diaminobiphenyl (alias: 2,2'-bis (trifluoromethyl) benzidine) and 2,2'-dimethyl-4,4'-diaminobiphenyl Benzidine) with an acid dianhydride containing 1,2,3,4-cyclobutanetetracarboxylic dianhydride, and a polyimide film obtained by reacting a diamine including one or two selected from the group consisting of 1,2,3,4- And an expansion coefficient of less than 45ppm / K, in the light of the light transmittance 308㎚ is 5% or less, in the light of 400㎚ a method for manufacturing a transparent polyimide film of not less than 70%.

The method for producing a transparent polyimide film of the present invention preferably satisfies any one or more of the following.

1) diamines selected from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and 2,2'-dimethyl-4,4'-diaminobiphenyl are reacted with 50 mol %, And further comprising at least 70 mol% of 1,2,3,4-cyclobutane tetracarboxylic dianhydride as the total acid dianhydride.

2) diamines other than 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl or 2,2'-dimethyl-4,4'-diaminobiphenyl, , Or an acid dianhydride other than 1,2,3,4-cyclobutane tetracarboxylic dianhydride in an amount of 1 to 30 mol% in the total acid dianhydride.

3) The polyimide film obtained has a yellowness value of 6 or less.

4) The polyimide layer is separated from the supporting substrate by irradiating laser light to the interface between the polyimide layer and the support.

Another aspect of the present invention is a process for producing a transparent polyimide film characterized by comprising a step of forming a functional layer on a polyimide layer and thereafter peeling the polyimide layer having the functional layer from the support A method for producing a transparent polyimide film having a functional layer.

In this case, the functional layer may be any one selected from the group consisting of a transparent conductive layer, a wiring layer, a conductive layer, a gas barrier layer, a thin film transistor, an electrode layer, a light emitting layer, an adhesive layer, a pressure sensitive adhesive layer, a transparent resin layer, Or two or more layers.

The polyimide precursor of the present invention can be polyimide excellent in dimensional stability, transparency and heat resistance by imidizing it. Further, after the polyimide precursor of the present invention is coated on the supporting substrate to form a polyimide film, the film is excellent in peelability (laser lift-off property) from the supporting substrate. Therefore, It can be obtained easily. The polyimide of the present invention can be suitably used as a practical flexible heat-resistant transparent resin substrate material that can take advantage of these properties and can substitute for a glass substrate for use in a display or a touch panel, and satisfies required characteristics such as dimensional stability have.

Further, according to the production method of the present invention, a thin transparent polyimide film excellent in dimensional stability, transparency and heat resistance and also excellent in film peelability (laser lift-off property) from the supporting substrate can be obtained easily. The transparent polyimide film obtained by the present invention is a practical flexible heat-resistant transparent resin substrate material that can take advantage of these properties and can substitute for a glass substrate for use in a display or a touch panel and satisfies required characteristics such as dimensional stability And can be suitably used.

<Polyimide precursor and polyimide>

The polyimide precursor (hereinafter also referred to as &quot; the present polyimide precursor &quot;) of the present invention is a polyimide precursor having a structural unit derived from a diamine and a polyimide precursor derived from an acid dianhydride (U1) derived from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and a structural unit derived from an acid dianhydride (U2) derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride, and the structural unit (U2) is a structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride, wherein 70 mol of the structural unit derived from the total acid dianhydride %.

As is well known, a polyimide precursor having a structural unit derived from a diamine and a structural unit derived from an acid dianhydride can be represented by the following general formula (1).

_{[-OCX (COOH) 2 CO-} HN-Y-NH-] (1)

The polyimide obtained by imidizing the polyimide precursor can be represented by the following general formula (2).

[-N (OC) ₂ X (CO) ₂ NY-] (2)

In the formulas (1) and (2), X is a quadrivalent residue formed by removing two acid dianhydrides from an acid dianhydride, and Y is a divalent residue formed by removing two amino groups from a diamine .

The present polyimide precursor can be obtained by using 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl (abbreviated as TFMB) represented by the following formula (3) And a structural unit derived from TFMB represented by the following formula (3a) as the structural unit (Y).

The present polyimide precursor preferably contains 50 mol% or more, more preferably 70 mol% or more, and still more preferably 80 mol% or more of the structural unit derived from TFMB in the structural units derived from the whole diamine. Within this range, the polyimide obtained by imidizing the present polyimide precursor is excellent in light transmittance at 400 nm and the transparency of the flexible substrate is improved, which is preferable.

The present polyimide precursor can be obtained by using 1,2,3,4-cyclobutanetetracarboxylic dianhydride (abbreviated as CBDA) represented by the following formula (4) as tetracarboxylic acid dianhydride, a structure derived from tetracarboxylic acid dianhydride As the unit (X), a structural unit derived from CBDA represented by the following formula (4a) is provided.

The present polyimide precursor contains a structural unit derived from CBDA in an amount of 70 mol% or more, more preferably 80 mol% or more in the structural units derived from the entire tetracarboxylic acid dianhydride. Within this range, the polyimide obtained by imidizing the present polyimide precursor is preferable because CTE is lowered while maintaining transparency, dimension stability of the flexible substrate is excellent, and warping of the flexible device can be suppressed.

Accordingly, a polyimide precursor having a structure derived from TFMB and a structure derived from CBDA and having a structural unit represented by the following formula (5), followed by imidation thereof to form a structural unit represented by the following formula (6) Polyimide can be obtained.

The present polyimide precursor may contain the structural unit represented by the formula (5) in an amount of preferably 50 to 97 mol%, more preferably 70 to 97 mol%, in the polyimide precursor. Similarly, in the present polyimide obtained by imidizing the present polyimide precursor, the structural unit represented by the formula (6) may be contained in the polyimide in an amount of preferably 50 to 97 mol%, more preferably 70 to 97 mol%.

The present polyimide precursor can be obtained by reacting a diamine containing TFMB with tetracarboxylic dianhydride containing 70 mol% or more of CBDA in the total acid dianhydride. Preferably, TFMB in the total diamine is 50 mol% or more.

But not only the two components of TFMB and CBDA but also the tetracarboxylic dianhydride components other than CBDA in the range of 1 to 30 mol%, preferably 1 to 20 mol%, as the dianhydride component, and / , 1 to 50 mol%, preferably 1 to 40 mol%, more preferably 1 to 30 mol%, of diamine components other than TFMB. Within this range, the light transmittance of the polyimide obtained by imidizing the present polyimide precursor is lowered to 308 nm, and the releasability (laser lift-off characteristic) is improved, which is preferable . When a diamine component other than TFMB is contained and a tetracarboxylic acid dianhydride component other than CBDA is contained at the same time, the polyimide obtained by imidizing the present polyimide precursor has a low light transmittance of 308 nm, The transmittance is increased, and the CTE is further lowered.

The diamine used for the copolymerization in addition to TFMB is a compound represented by H ₂ N-Ar ¹ -N ₂ H, and Ar ¹ is preferably an aromatic diamine residue represented by the following formula (7). This corresponds to Y in the above equations (1) and (2).

Among these diamines, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 5-amino-2- (4-aminophenyl) benzoimidazole (AAPBZI) (4-aminophenyl) benzoxazole (AAPBZO) is exemplified as suitable.

When these diamine components other than TFMB are used in combination, the use ratio thereof is preferably 1 to 50 mol%, more preferably 1 to 30 mol%, based on the total diamine.

The tetracarboxylic acid dianhydride used in the copolymerization in addition to CBDA is a compound represented by the following formula (8)

As Ar ² , an aromatic diamine residue represented by the following formula (9) is preferably exemplified. This corresponds to X in the above-mentioned expressions (1) and (2).

Among these tetracarboxylic dianhydrides, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) or 2,2'-bis (3,4-dicarboxyphenyl) Structural units derived from hexafluoropropane dianhydride (6FDA) are exemplified as suitable.

When these tetracarboxylic acid dianhydride components other than CBDA are used in combination, the use ratio thereof is 1 to 30 mol%, preferably 1 to 28 mol%, more preferably 1 to 20 mol%, based on the total tetracarboxylic acid dianhydride, Preferably 1 to 10 mol%.

In the description of the structural unit, terms such as a structural unit derived from a diamine or a structural unit derived from an acid dianhydride are used. For the sake of convenience, the term &quot; And it is not limited to the raw materials and the production conditions. Concretely, in the formulas (1) and (2), a structural unit derived from an acid dianhydride is X, a structural unit derived from a diamine is interpreted as Y, and is not interpreted to mean a raw material or a manufacturing method . Since the structural units and ratios of the polyimide precursors are determined by the kind and ratio of the diamine and the acid dianhydride, the description of the structural unit can be explained by the diamine and the acid dianhydride. The use ratio of the diamine and the acid dianhydride is the ratio of the proportion of the structural unit derived from each. For example, the use ratio (mol%) of CBDA in the total acid dianhydride is the content (mol%) of the structural units derived from CBDA in the total structural units derived from the acid dianhydride. (Mol%) of the structural units derived from TFMB in the total structural units derived from diamine, and the like.

The polyimide precursor and the polyimide of the present invention can be obtained by reacting a tetracarboxylic dianhydride and a diamine, which are known in the general production method, to obtain a polyimide precursor (also referred to as polyamic acid or polyamic acid) A method of making polyimide by a reaction (ring closing reaction) can be used.

In the present invention, the above-mentioned tetracarboxylic acid dianhydride that can be used in combination with CBDA can be mentioned, and further examples include naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,5,6 - tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', 4 , 4'-benzophenonetetracarboxylic dianhydride, 2,2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, naphthalene-1,2 , 4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride, 4,8- 3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-2,3 , 6,7-tet Dicarboxylic acid dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,3,6 , 7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic acid dianhydride, 2,2 ' 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3 ', 4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-p-terphenyltetracarboxylic dianhydride, 2, 3 &quot; -p-terphenyltetracarboxylic dianhydride, 2,3,3 &quot;, 4 &quot; -p- terphenyltetracarboxylic dianhydride, 2,2- bis (2,3- (2,3-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis Water, bis (3,4-dicarboxyphenyl) methane dianhydride, bis (2,3-di Bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1- Perylene-2,3,8,9-tetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic acid dianhydride, perylene-4,5,10,11- Tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic acid dianhydride, phenanthrene-1,2,6,7-tetracarboxylic acid Dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic acid dianhydride, Pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, (trifluoromethyl) Pyromellitic dianhydride, di (trifluoro (Heptafluoropropyl) pyromellitic acid dianhydride, pentafluoroethyl pyromellitic dianhydride, bis {3,5-di (trifluoromethyl) phenoxy} pyromellitic acid dianhydride, Dianhydride, 2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxybis Phenyl dianhydride, 2,2 ', 5,5'-tetrakis (trifluoromethyl) -3,3', 4,4'-tetracarboxybiphenyl dianhydride, 5,5'-bis (trifluoro Methyl) -3,3 ', 4,4'-tetracarboxydiphenyl ether dianhydride, 5,5'-bis (trifluoromethyl) -3,3', 4,4'-tetracarboxybenzophenone dianhydride , Bis {(trifluoromethyl) dicarboxyphenoxy} benzene dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} trifluoromethylbenzene dianhydride, bis (dicarboxyphenoxy) trifluoromethyl Ben Benzene dianhydride, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene dianhydride, 2,2-bis {(4- ( (Trifluoromethyl) dicarboxyphenoxy) phenyl} hexafluoropropane dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} biphenyl dianhydride, bis { (Trifluoromethyl) biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} diphenyl ether dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl dianhydride, .

In the present invention, the diamines that can be used in combination with TFMB include the diamines described above. For example, 2,2'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethyl- Diaminobiphenyl, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenyl Dienamin mesitylene, 4,4'-methylene di-o-toluidine, 4,4'-methylene di-2,6-xylidine, 4,4'-methylene-2,6 Diaminodiphenyl propane, 3,3'-diaminodiphenyl propane, 4,4'-diaminodiphenyl propane, 4,4'-diaminodiphenyl propane, Diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis [4- (4 -Aminophenoxy) phenyl] propane, 4,4'-diaminodiphenylsulfide, 3,3'-diaminodiphenylsulfide, 4,4'-diamine Diphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether, 1,3-bis (3-aminophenoxy) (4-aminophenoxy) benzene, 4,4'-diaminobiphenyl, 3,3'-diaminobiphenyl, 3,3'- , 3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4'-diamino-p- Bis (p-beta-amino-t-butylphenyl) ether, bis (p- Aminopentyl) benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6- diaminonaphthalene, 2,4- Butylenesulfonic acid, 2,6-diisobutylenediamine, p-xylylene diamine, p-xylylene diamine, p-xylylene diamine, Diaminopyridine, 2,5-diaminopyridine, 2,5-diamino -1,3,4-oxadiazole, and piperazine.

The precursor of the polyimide of the present invention is prepared by a known method of polymerizing in an organic polar solvent (organic polar solvent) using a molar ratio (substantially equimolar) of diamine and acid dianhydride of 0.9 to 1.1 . Specifically, a diamine is dissolved in a nonprotonic amide solvent such as N, N-dimethylacetamide or N-methyl-2-pyrrolidone in a nitrogen stream, acid dianhydride is added and the mixture is stirred at room temperature for 3 to 20 hours . At this time, the terminal of the molecule may be sealed with an aromatic monoamine or an aromatic monocarboxylic acid dianhydride. As the solvent, dimethylformamide, 2-butanone, diglyme, xylene, gamma -butyrolactone, and the like can be given, and they can be used alone or in combination of two or more.

The polyimide of the present invention is obtained by imidizing the polyimide precursor of the present invention. Imidization can be accomplished by thermal imidization or chemical imidization. The thermal imidization may be performed by applying a polyimide precursor on an arbitrary support substrate (support substrate) such as glass, metal, resin (polyimide film, etc.) using an applicator, After preliminary drying for 60 minutes, for removal of the solvent and imidation, usually, the heat treatment is performed at a temperature of about room temperature to about 360 ° C for about 30 minutes to 24 hours. In the chemical imidization, a dehydrating agent and a catalyst are added to a solution of a polyimide precursor (also referred to as &quot; polyamic acid &quot;) and chemically dehydrated at 30 to 60 占 폚. Representative dehydrating agents include acetic anhydride and pyridine as a catalyst. The thermal imidization is completed in a relatively short time in accordance with the combination of the acid dianhydride, the kind of the diamine, and the kind of the solvent, and the heat treatment including the preheating can be performed within 60 minutes. It is also possible to use both thermal imidization and chemical imidization. When the polyimide precursor is applied, the polyimide precursor may be applied as a polyimide precursor solution in which the polyimide precursor is dissolved in a known solvent. The thickness of the supporting substrate may be, for example, about 0.02 to 1.0 mm.

The preferred degree of polymerization of the polyimide precursor and polyimide of the present invention is a viscosity measured by an E-type viscometer of the polyimide precursor solution, and is preferably 1,000 to 40,000 cP, and preferably 3,000 to 5,000 cP. The molecular weight of the polyimide precursor can be determined by the GPC method. The preferred molecular weight range (in terms of polystyrene) of the polyimide precursor is preferably 15,000 to 250,000 in number average molecular weight, and 30,000 to 800,000, preferably 50,000 to 300,000 in weight average molecular weight, but this is a target, Not all of the mid precursor can be used. The molecular weight of the polyimide is also in the range equivalent to the molecular weight of the precursor.

The polyimide of the present invention can form a thin polyimide layer (film) on a supporting substrate, and can obtain a transparent polyimide film exhibiting excellent performance in terms of transparency, dimensional stability, heat resistance and ease of peeling from the supporting substrate have. That is, the light transmittance is 70% or more, preferably 80% or more, and the coefficient of thermal expansion (CTE) is 45 ppm / K or less, preferably 35 ppm / K or less , More preferably 30 ppm / K or less, and can be easily peeled from the support substrate by a known method. In particular, the polyimide of the present invention has a light transmittance of 5% or less, preferably 3% or less, in a wavelength range (wavelength region) (for example, 308 nm) of a laser beam, (Laser lift off) (LLO) from the support substrate by irradiation with laser light is excellent, and the thickness is 30 mu m or less, More preferably 20 占 퐉 or less, and even more preferably 15 占 퐉 or less.

Here, when the polyimide of the present invention is used as a polyimide film, preferably used as a flexible device, more preferably, a functional layer on which a functional layer (functional layer) is formed on a polyimide film , The light transmittance is a value measured for the film unless otherwise specified. In a preferred embodiment, the thickness is a value measured in the state of a film having a thickness of 10 to 15 占 퐉. In any one of the thickness ranges, the transmittance may be given. In a more preferred embodiment, it is a value measured in a film state having a thickness of 13 mu m. In this case, the value measured in the film state of about 13 mu m in thickness can be converted into a value converted into a film of 13 mu m. The coefficient of thermal expansion (CTE) is a coefficient of linear expansion when the temperature is changed from 250 DEG C to 100 DEG C unless otherwise specified. The polyimide of the present invention has a difference in thermal expansion coefficient (10 ppm / K or less) And therefore, it is excellent in shape stability when the glass is used as a supporting substrate. For example, a flexible substrate such as a TFT substrate for an organic EL device having a bottom emission structure or a top emission structure, a functional panel in a touch panel substrate, a color filter, etc., It is possible to suppress the warp of the substrate when the device is manufactured, and the fabrication yield of the flexible device is excellent. In addition, it is possible to absorb light in the invisible light region (invisible light region) and increase the transmittance in the visible light region. Within this range, the laser light (excimer laser) of 308 nm can be absorbed while maintaining the transparency of the visible light region. As a result, the polyimide layer (film) was peeled off from the glass without damaging the display device on the transparent polyimide layer by laser irradiation of a flexible substrate such as a substrate for an organic EL device, a touch panel substrate, or a color filter substrate, And can be suitably manufactured by a laser lift-off method. It is preferable that the yellowness degree (YI) is 6 or less, preferably 4 or less. Within this range, it can be suitably used for a substrate which is required to be transparent or colorless, such as a TFT substrate for an organic EL device, a touch panel substrate, and a color filter substrate. Further, from the viewpoint of heat resistance, the glass transition temperature is 300 占 폚 or higher, preferably 350 占 폚 or higher, more preferably 380 占 폚 or higher, and the thermal decomposition temperature (Td1) is 350 占 폚 or higher, preferably 380 占 폚 or higher.

Further, since the polyimide of the present invention is imidized by dehydrating and ring-closing (ring closing) the polyimide precursor, the arrangement of the structural units remains the same. The polyimide precursor of the present invention satisfies the above-mentioned characteristics such as light transmittance and thermal expansion coefficient when polyimide is used, and is common.

The polyimide film obtained by using the polyimide (precursor) of the present invention replaces the glass substrate, which is a conventional material, for a thin display or a touch panel, and satisfies the required characteristics such as dimensional stability and is a practical flexible heat- And the like. That is, a polyimide film can be used as a substrate material, and functional layers such as devices having various functions can be formed on the surface thereof. For example, a thin film transistor (TFT), a color filter, a conductive film, a gas barrier film, an organic EL display device, a touch panel and an electronic paper, as well as a main display device such as a liquid crystal display device, A flexible circuit board, an adhesive film, or the like can also be formed.

In this case, the polyimide film may be composed of not only a single layer but also a plurality of layers of polyimide.

The forming method of the functional layer is appropriately set according to the intended device. Generally, after forming a film of a metal film, an inorganic film, an organic film, or the like on a polyimide film, Followed by patterning in a predetermined shape or heat treatment. That is, the means for forming these display elements is not particularly limited and may be suitably selected, for example, by sputtering, vapor deposition, CVD, printing, exposure, or dipping. If necessary, these processes are performed in a vacuum chamber or the like . After the functional layer is formed on the polyimide film, the separation of the supporting substrate and the polyimide film having the functional layer may be performed immediately after the functional layer is formed through various process processes, or after a certain period of time has elapsed It may be integrally formed with the supporting substrate, and may be separated and removed immediately before use as a display device, for example.

After forming a functional layer on the polyimide layer (film) formed on the supporting substrate by using the polyimide (precursor) of the present invention, the polyimide film is peeled from the supporting substrate by the functional layer. For example, after completing the assembling and manufacturing processes of various electronic parts forming the functional layer on the polyimide film, a polyimide film (film) having a functional layer is formed on the obtained polyimide film having the functional layer on the supporting substrate And is peeled from the supporting substrate by irradiation with laser light. As described above, when the excimer laser (wavelength: 308 nm) is used to irradiate the interface between the supporting substrate (glass) and the polyimide film, the polyimide film having the functional layer can be easily separated from the supporting substrate.

(Examples of polyimide precursor and polyimide)

Hereinafter, the present invention will be described in detail with reference to examples and comparative examples. The present invention is not limited to these examples.

The abbreviations of the raw materials used in Examples and the like are shown below.

TFMB: 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl

M-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl

4,4'-DAPE: 4,4'-diaminodiphenyl ether

CBDA: 1,2,3,4-Cyclobutane tetracarboxylic acid dianhydride

PMDA: pyromellitic dianhydride

BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride

6FDA: 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride

NMP: N-methyl-2-pyrrolidone

The measuring method and the evaluation method of each property in Examples and the like are shown below.

[Light Transmittance and Yellowness Index (YI)]

(T308, T355, T400, and T430) at 308 nm, 355 nm, 400 nm, and 430 nm of a polyimide film (50 mm x 50 mm, thickness 10-15 m) And it was measured by a UV-3600 spectrophotometer of SHIMADZU CORPORATION. The YI (yellowness index) was calculated based on the following equation.

YI = 100 x (1.2879X-1.0592Z) / Y

X, Y and Z are the tristimulus values of the test piece (tristimulus values) and are specified in JIS Z 8722.

[Thermal Expansion Coefficient (CTE)]

A polyimide film having a size of 3 mm x 15 mm was heated to a temperature of 30 占 폚 to 280 占 폚 at a constant temperature raising rate (10 占 폚 / min) while applying a load of 5.0 g with a thermomechanical analysis (TMA) The coefficient of thermal expansion was measured from the elongation (elongation) (linear expansion) of the polyimide film at the time of lowering the temperature from 250 占 폚 to 100 占 폚 and cooling down.

[Glass transition temperature (Tg)]

The dynamic viscoelasticity (dynamic viscoelasticity) when the polyimide film (5 mm x 70 mm) was heated from 23 deg. C to 500 deg. C at a rate of 5 deg. C / min was measured with a dynamic thermomechanical analyzer to determine the glass transition temperature : &Lt; / RTI &gt;

[Pyrolysis temperature (Td1)]

Under a nitrogen atmosphere, a polyimide film weighing 10 to 20 mg was heated at 30 DEG C to 550 DEG C at a constant speed by TG / DTA6200, a thermogravimetric analysis (TG) apparatus manufactured by Seiko Instruments Incorporated, , The weight at 200 캜 was set to zero, and the temperature at which the weight loss rate was 1% was determined as the thermal decomposition temperature (Td 1).

[Peelability: LED]

(MJ / cm &lt; 2 &gt;) (abbreviation: LED) until the polyimide layer and the support substrate (glass substrate) are peeled off. The irradiation conditions are the same as in &quot; peelability: laser lift off (LLO) &quot; described in the next paragraph. The higher the energy density, the more difficult it is to peel off. Even though the lifetime of the laser irradiation apparatus is considered, it is preferable that the irradiation energy density is low. The upper limit of the measurement is 300 mJ / cm 2, and when it can not be peeled off at 300 mJ / cm 2 or lower, "x" is set.

[Peelability: laser lift off (LLO)]

A laser beam having a beam size of 14 mm x 1.2 mm, a moving speed of 6 mm / s and an overlap ratio of 80% was irradiated from the side of the supporting substrate (glass) using an excimer laser processing machine (wavelength of 308 nm) The entire surface of the supporting substrate and the polyimide layer or the entire surface of the supporting substrate and the polyimide layer was measured in a state where the layer was completely separated (the peeling range was determined by a cutter and the polyimide film was naturally peeled off from the glass after one perforation line was inserted) &Quot; x &quot; was defined as a state in which part of the polyimide layer could not be separated or the polyimide layer was discolored.

Example 1

Under a nitrogen stream, 9.17 g of TFMB was dissolved in 85 g of NMP in a 100 ml separable flask. Then, 5.00 g of CBDA was added to this solution. After stirring for 10 minutes, 0.83 g of BPDA was added. The molar ratio of the diamine component to the tetracarboxylic dianhydride component was 0.99 (substantially equivalent). Thereafter, this solution was stirred at room temperature for 24 hours to carry out a polymerization reaction to obtain a polyamic acid (A) having a high polymerization degree (Mw of 80,000 or more and a viscosity of 3,000 cP or more) Colorless solution).

Examples 2 to 9 and Comparative Examples 1 to 7

A polyamic acid solution was prepared in the same manner as in Example 1 except that diamine and tetracarboxylic dianhydride as raw materials were changed to the compositions shown in Table 1 and Table 2 to obtain polyamic acid (B to P).

Further, in Table 1 and Table 2, the unit of the amount of the diamine and the tetracarboxylic dianhydride is g, and the numerical value in the parentheses represents the mol% in the diamine component or the tetracarboxylic dianhydride component.

Example 10

Solvent NMP was added to the polyimide precursor solution (A) obtained in Example 1 to dilute the solution to a viscosity of 4000 cP. Thereafter, a glass substrate (E-XG manufactured by Corning Incorporated, size = 150 mm x 150 mm , Thickness = 0.7 mm) was applied using a spin coater so that the thickness of the polyimide after curing was about 15 탆. Followed by heating at 100 DEG C for 15 minutes. Then, the temperature was raised from room temperature to 300 占 폚 (360 占 폚 in Comparative Example 10) at a constant heating rate (3 占 폚 / min) in a nitrogen atmosphere, held at 130 占 폚 for 10 minutes in the middle, A polyimide layer (polyimide (A)) was formed to obtain a polyimide laminate (A).

Examples 11 to 18 and Comparative Examples 8 to 14

Polyimide laminate (B to P) was obtained in the same manner as in Example 10 except that the polyimide precursor was changed to any one of the polyimide precursors (B to P). The polyimide precursor and the polyimide laminate correspond to each other and the polyimide precursor (B) to obtain the polyimide laminate (B).

The obtained polyimide laminate (A to P) was measured for laser lift off (LLO) and LED. The results are shown in Tables 3 and 4.

The polyimide film was peeled off from the laminate in the measurement of various physical properties except the above, but the laminate in this case was prepared in the same manner as above except that a polyimide film of 75 mu m was used as the substrate instead of the glass substrate . Detailed preparation conditions are shown below.

The solvent NMP was added to the polyamic acid solutions (A to P) obtained in Examples 1 to 9 and Comparative Examples 1 to 7 to dilute the resulting solution to a viscosity of 3000 cP. Then, a polyimide film (Upilex-S) Respectively. Followed by heating at 100 DEG C for 15 minutes. The temperature was raised from room temperature to 300 占 폚 (360 占 폚 in Comparative Example 10) at a constant temperature raising rate (3 占 폚 / min) in a nitrogen atmosphere, and maintained at 130 占 폚 for 10 minutes in the middle to obtain a polyimide laminated film. Subsequently, the polyimide substrate (Upilex-S) was peeled off to form polyimide films (A to P) as a single body obtained by imidizing the polyamic acid solutions (A to P). In the peeling, only the formed polyimide layer was cut with a cutter to form a perforated line, and then peeled off from the substrate with a tweezers. The thickness of these films is shown in the item of thickness in Tables 3 and 4 below.

The obtained polyimide films (A to P) were subjected to various evaluations such as CTE, light transmittance, YI, Td1 and Tg. The results are shown in Tables 3 and 4.

&Lt; Method for producing transparent polyimide film >

The method for producing a transparent polyimide film of the present invention is characterized in that a polyimide precursor is coated on a support (support substrate) and imidized to form a polyimide layer, and then the polyimide layer is peeled off from the support substrate, It is preferable to produce a polyimide film to be used as a transparent resin substrate material having a thickness of 30 mu m or less, more preferably 20 mu m or less, more preferably 15 mu m or less.

As is well known, the polyimide precursor can be represented by the following general formula (10).

_{[-OCX (COOH) 2 CO-} HN-Y-NH-] (10)

The polyimide obtained by imidizing the polyimide precursor can be represented by the following general formula (11).

In the formulas (10) and (11), X is a tetravalent residue formed by removing two acid dianhydrides from an acid dianhydride, and Y is a bivalent residue formed by removing two amino groups from a diamine .

[-N (OC) ₂ X (CO) ₂ NY-] (11)

For the synthesis of the polyimide precursor (polyamic acid), diamine and tetracarboxylic acid dianhydride are used. In the production process of the present invention, as the diamine, 2,2'-bis (trifluoromethyl) ) -4,4'-diaminobiphenyl (abbreviated as TFMB) or 2,2'-dimethyl-4,4'-diaminobiphenyl represented by the following formula (12b) One or two diamines are used.

(12a)

(12a)

(12b)

(12b)

In the process of the present invention, TFMB or m-TB is used as an essential component as a diamine. A structural unit derived from TFMB or m-TB is converted into a structural unit derived from a total diamine by using at least 50 mol%, preferably at least 70 mol%, more preferably at least 80 mol% of TFMB or m- It is included in a ratio corresponding to the above. Use of TFMB or m-TB in the above range is preferable because the light transmittance of the visible light of the polyimide is improved and the transparency of the flexible substrate is improved.

In the production process of the present invention, 1,2,3,4-cyclobutane tetracarboxylic dianhydride (abbreviation: CBDA) represented by the following formula (13) is used as an essential component as the tetracarboxylic acid dianhydride.

(13)

(13)

When CBDA is used in an amount of 70 mol% or more, preferably 80 mol% or more of the total acid dianhydride, the structural units derived from CBDA are included in the structural units derived from the total acid dianhydride in a proportion corresponding thereto. When CBDA is used in the above range, the CTE of the obtained polyimide is low. This improves the dimensional stability of the flexible substrate using polyimide, and makes it possible to suppress warping of the flexible device.

In the process of the present invention, the polyimide precursor can be obtained by reacting a diamine containing one or two selected from TFMB or m-TB with a tetracarboxylic dianhydride containing CBDA. The total diamine may contain TFMB or m-TB in an amount of preferably 50 mol% or more. Further, CBDA is preferably contained in the total acid dianhydride in an amount of preferably 70 mol% or more.

But not limited to, TFMB or m-TB, and CBDA as well as an acid dianhydride component, a tetracarboxylic dianhydride component other than CBDA in the range of 1 to 30 mol%, and / or a diamine component in an amount of 1 to 50 mol% , Preferably from 1 to 40 mol%, more preferably from 1 to 30 mol%, of diamine components other than TFMB or m-TB. Within this range, the polyimide obtained by imidizing the polyimide precursor is preferable because the light transmittance of 308 nm is lowered and the peelability (laser lift off property) is improved. When a polyimide precursor is included in a polyimide precursor by including a tetracarboxylic dianhydride component other than CBDA in the case of containing a diamine component other than TFMB or m-TB, the polyimide having a low light transmittance of 308 nm, It is more preferable since the light transmittance is high and the CTE is low.

Thus, a polyimide precursor having a structure derived from TFMB or m-TB and a structure derived from CBDA, followed by imidation thereof, to obtain a polyimide having a structural unit represented by the following formula (15) . Further, in the equation (14), (15), the diamine-derived structures, shows a case of using the TFMB as a raw material, as a raw material in the case of using the m-TB, a methyl group (CF ₃₎ trifluoromethyl both Methyl group (CH ₃ ), and when two of them are used together, they have a structure in which they coexist according to the amount of use.

(14)

(14)

(15)

(15)

The polyimide precursor used in the process of the present invention may contain the structural unit represented by the formula (14) in the polyimide precursor in an amount of preferably 50 to 97 mol%, more preferably 70 to 97 mol%. Likewise, the polyimide used in the process of the present invention, which is obtained by imidizing the polyimide precursor, preferably has a structural unit represented by the formula (15) in the polyimide in an amount of preferably 50 to 97 mol%, more preferably 70 to 97 mol % Should be included.

In addition to TFMB or m-TB, examples of the diamine used for copolymerization include 3,3'-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminodiphenyl ether, 3,4 ' Diaminodiphenyl ether, 4,6-dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesityylene, 4,4'- Toluene, 4,4'-methylene di-2,6-xylylidine, 4,4'-methylene-2,6-diethylaniline, 2,4-toluene diamine, m- , 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'- Diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane 4,4'-diaminodiphenylsulfide, 3,3'- Diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, Diaminobiphenyl, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl, 3,3'-dimethoxy-4,4'- Diaminobiphenyl, 4,4'-diamino-p-terphenyl, 3,3'-diamino-p-terphenyl, bis (p- Benzene, p-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,4-bis (? -Amino-t-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p- m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5 diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, .

Of these diamines, 5-amino-2- (4-aminophenyl) benzoimidazole (AAPBZI) or 5-amino-2- (4-aminophenyl) benzoxazole (AAPBZO) are exemplified as suitable.

When the diamine component other than TFMB or m-TB is used in combination, the use ratio thereof is preferably 1 to 50 mol%, more preferably 1 to 30 mol%, based on the total diamine.

Examples of the tetracarboxylic dianhydride used in the copolymerization in addition to CBDA include 4,4 '(2,2'-hexafluoroisopropylidene) diphthalic acid dianhydride ("bis (3,4-dicarboxyphenyl) Hexafluoropropane dianhydride "or" 6FDA "), naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride, naphthalene- 1,2,3,4-tetracarboxylic acid dianhydride, pyromellitic dianhydride, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, 3,3', 4,4'-benzophenonetetracarboxylic acid Dianhydride, 2,2 ', 3,3'-benzophenonetetracarboxylic dianhydride, 2,3,3', 4'-benzophenonetetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic acid dianhydride Water, naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,2 , 6,7-tetracarboxylic acid dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic acid dianhydride, 4,8-dimethyl -1,2,3,5,6,7-hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 2,3,6,7-tetrachloronaphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 1,4,5 , 8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic acid dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetra Carboxylic acid dianhydride, 3,3 '', 4,4'-p-terphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-terphenyltetracarboxylic dianhydride, 2,3,3' (2,3-dicarboxyphenyl) -propane dianhydride, 2,2-bis (3,4-dicarboxy Bis (2,3-dicarboxyphenyl) methane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis Bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1- (3,4-dicarboxyphenyl) ethane dianhydride, perylene-2,3,8,9-tetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic acid dianhydride, perylene- 5,10,11-tetracarboxylic dianhydride, perylene-5,6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic acid dianhydride, phenanthrene- 6,7-tetracarboxylic dianhydride, phenanthrene-1,2,9,10-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6 - tetracarboxylic acid dianhydride, pyrrolidine-2,3,4,5-tetra (Trifluoromethyl) pyromellitic acid dianhydride, di (trifluoromethyl) pyrochlore, di (trifluoromethyl) pyrazole, dihydrocarbylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'oxydiphthalic dianhydride, (Heptafluoropropyl) pyromellitic dianhydride, pentafluoroethyl pyromellitic dianhydride, bis {3,5-di (trifluoromethyl) phenoxy} pyromellitic acid dianhydride, (2,2-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride, 5,5'-bis (trifluoromethyl) -3,3 ', 4,4'-tetracarboxybiphenyl dianhydride , 2,2 ', 5,5'-tetrakis (trifluoromethyl) -3,3', 4,4'-tetracarboxybiphenyl dianhydride, 5,5'-bis (trifluoromethyl) 3,3 ', 4,4'-tetracarboxybenzophenone dianhydride, bis {3,5'-bis (trifluoromethyl) (Trifluoromethyl ) Dicarboxyphenoxy} benzene dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} trifluoromethylbenzene dianhydride, bis (dicarboxyphenoxy) trifluoromethylbenzene dianhydride, bis Bis (trifluoromethyl) benzene dianhydride, bis (dicarboxyphenoxy) tetrakis (trifluoromethyl) benzene dianhydride, 2,2-bis {{4- (3,4-dicarboxyphenoxy) Bis (trifluoromethyl) dicarboxyphenoxy} biphenyl dianhydride, bis {(trifluoromethyl) dicarboxyphenoxy} bis (trifluoromethyl) bis Bis (trifluoromethyl) dicarboxyphenoxy} diphenyl ether dianhydride, bis (dicarboxyphenoxy) bis (trifluoromethyl) biphenyl dianhydride, and the like.

Of these tetracarboxylic acid dianhydrides, 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride (BPDA), pyromellitic dianhydride (PMDA) or 6FDA is exemplified as suitable.

When these tetracarboxylic dianhydride components other than CBDA are used in combination, the proportion thereof is preferably 1 to 30 mol%, more preferably 1 to 28 mol%, and even more preferably 1 to 30 mol%, based on the total tetracarboxylic acid dianhydride. 20 mol%, and more preferably 1 to 10 mol%.

In the process of the present invention, the polyimide precursor (polyamic acid) is prepared by a known method of polymerizing in an organic polar solvent using a molar ratio of diamine and acid dianhydride of 0.9 to 1.1 (substantially equivalent) . Specifically, a diamine is dissolved in an aprotic amide solvent such as N, N-dimethylacetamide or N-methyl-2-pyrrolidone in a nitrogen stream, acid dianhydride is added thereto, Time. At this time, the terminal of the molecule may be sealed (sealed) with an aromatic monoamine or an aromatic monocarboxylic acid anhydride. As the solvent, dimethylformamide, 2-butanone, diglyme, xylene,? -Butyrolactone, and the like can be given, and they may be used alone or in combination of two or more.

In the process of the present invention, the thus obtained polyimide precursor is imidized by a thermal imidization method or a chemical imidization method. For thermal imidization, a polyimide precursor is applied to an arbitrary support substrate such as glass, metal, resin (polyimide film, etc.) using an applicator, preliminarily dried for 3 to 60 minutes at a temperature of 130 DEG C or lower After heat treatment for about 30 minutes to 24 hours at a temperature of usually about room temperature to about 360 ° C for solvent removal and imidization. In the chemical imidization, a dehydrating agent and a catalyst are added to a polyimide precursor (also referred to as &quot; polyamic acid &quot;) solution and chemically dehydrated at 30 to 60 占 폚. Representative dehydrating agents include acetic anhydride and pyridine as a catalyst. Thermal imidization can be completed in a relatively short time in accordance with the combination of acid dianhydride, diamine type, and solvent type, and the heat treatment including preheating can be performed within 60 minutes. Thermal imidization and chemical imidization can also be used in combination. When the polyimide precursor is applied, the polyimide precursor may be applied as a polyimide precursor solution in which the polyimide precursor is dissolved in a known solvent. The thickness of the supporting substrate may be, for example, about 0.02 to 1.0 mm. When the polyimide precursor is applied, the polyimide precursor may be applied as a polyimide precursor solution in which the polyimide precursor is dissolved in a known solvent.

The preferred degree of polymerization of the polyimide precursor and the polyimide in the process of the present invention is a viscosity measured by an E-type viscometer of the polyimide precursor solution and is in the range of 1,000 to 40,000 cP, preferably 3,000 to 5,000 cP good. The molecular weight of the polyimide precursor can be determined by the GPC method. The preferred molecular weight range (in terms of polystyrene) of the polyimide precursor is preferably 15,000 to 250,000 in number average molecular weight, and 30,000 to 800,000, preferably 50,000 to 300,000 in weight average molecular weight. Not all of the polyimides can be used. The molecular weight of the polyimide is also in the range equivalent to the molecular weight of the precursor.

In the process of the present invention, various fillers and additives may be added to the polyimide precursor or polyimide as needed within the range not impairing the object of the present invention. For example, inorganic fine particles such as silica, alumina, boron nitride, and aluminum nitride may be added for the purpose of improving the sliding property and improving the thermal conductivity.

In the polyimide laminate having the polyimide layer formed on the surface of the support (support substrate), the polyimide layer is peeled from the support to obtain a polyimide film. The peeling may be carried out by any suitable means depending on the type of support. If the support is a copper foil or the like, there is a means for dissolving it in an acid. When the support is a resin (polyimide) film, polyimide having a thickness of 25 占 퐉 or more and a heat resistance of 400 占 폚 or more is suitable. When the support is made of a transparent material such as a glass substrate, a laser lift off (LLO) method is suitable. In the LLO method, a laser beam is irradiated on the glass substrate side. If the laser beam has a wavelength in the ultraviolet ray region, preferably near 308 占 퐉, it is efficiently absorbed by the polyimide film obtained in the present invention to generate heat, and at the same time, the laser beam is interposed between the glass substrate and the polyimide layer Thereby facilitating or enabling peeling.

The polyimide film obtained by the production method of the present invention may be composed of not only a single layer but also a plurality of layers of polyimide.

A thin polyimide layer (film) can be formed on the supporting substrate by the production method of the present invention, and a transparent polyimide film exhibiting excellent performance in terms of transparency, dimensional stability, heat resistance and ease of peeling from the supporting substrate can be obtained . (CTE) of not more than 45 ppm / K, preferably not more than 35 ppm / K, more preferably not more than 30 ppm / K, in a light ray having a wavelength of 400 nm, that is, a light transmittance of not less than 70% , And can be easily peeled off from the supporting substrate by a known method. In particular, in the process of the present invention, the polyimide has a light transmittance of 5% or less, preferably 3% or less, in the wavelength range of the laser beam (for example, 308 nm) (Laser lift off) (LLO) from the support substrate by irradiation with laser light is excellent, and the thickness is 30 mu m or less, More preferably not more than 20 占 퐉, still more preferably not more than 15 占 퐉.

Here, the coefficient of thermal expansion (CTE) is a coefficient of linear expansion when the temperature is changed from 250 캜 to 100 캜, unless otherwise specified. The polyimide in the process of the present invention has a coefficient of thermal expansion (10 ppm / K or less) From the point that the difference is not large, the shape stability is excellent when the glass is used as the supporting substrate. It is possible to suppress the warping of the substrate during manufacture of a flexible device such as a functional layer stack in a TFT substrate, a touch panel substrate, a color filter, and the like for an organic EL device having a bottom emission structure or a top emission structure And the production yield of the flexible device is excellent. In addition, it is possible to absorb light in the invisible light region and increase the transmittance in the visible light region. With this range, it is possible to absorb the 308 nm laser light (excimer laser) while maintaining the transparency of the visible light region. As a result, the polyimide layer (film) is peeled off from the glass without adversely affecting the display device on the transparent polyimide layer by laser irradiation of a flexible substrate such as a substrate for an organic EL device, a touch panel substrate, or a color filter substrate, And can be suitably manufactured by a lift-off method. The yellowness index (YI) is preferably 6 or less, and more preferably 4 or less. Within this range, it can be suitably used for substrates such as TFT substrates for organic EL devices, touch panel substrates, and color filter substrates, which are required to have transparency or colorlessness. Further, from the viewpoint of heat resistance, the glass transition temperature is 300 占 폚 or higher, preferably 350 占 폚 or higher, more preferably 380 占 폚 or higher, and the thermal decomposition temperature (Td1) is 340 占 폚 or higher, preferably 380 占 폚 or higher.

The polyimide film obtained by the production method of the present invention can be suitably used as a practical flexible heat-resistant transparent resin substrate material which satisfies required characteristics such as dimensional stability and the like in place of a glass substrate which is a conventional material in applications such as thin displays and touch panels . That is, the polyimide film can be used as a substrate material, and a functional layer such as an element having various functions can be formed on the surface thereof. For example, not only a main display device such as a liquid crystal display device, an organic EL display device, a touch panel, and an electronic paper but also a related component such as a thin film transistor (TFT), a color filter, a conductive film, A flexible circuit board, an adhesive film, or the like can also be formed.

In this case, the polyimide film may be composed of not only a single layer but also a plurality of layers of polyimide.

The formation method of the functional layer is appropriately set depending on the intended device. Generally, after forming a metal film, an inorganic film, an organic film, or the like on a polyimide film, , Or by a known method such as heat treatment. That is, the means for forming these display elements is not particularly limited, and may be suitably selected, for example, by sputtering, vapor deposition, CVD, printing, exposure, or dipping, and these processing steps may be carried out in a vacuum chamber if necessary . After the functional layer is formed on the polyimide film, the polyimide film having the supporting substrate and the functional layer may be separated from the polyimide film immediately after the functional layer is formed through various process treatments or after a certain period of time It may be integrally formed with the supporting substrate and removed, for example, immediately before use as a display device.

In the production method of the present invention, the polyimide layer (film) formed on the supporting substrate is further formed with a functional layer thereon, and then the polyimide film is peeled from the supporting substrate by the functional layer. For example, after completing the assembling process of various electronic parts forming the functional layer on the polyimide film, the polyimide film having the functional layer on the obtained supporting substrate is irradiated with the laser beam to form the polyimide layer with the functional layer (Film) is peeled from the supporting substrate. As described above, when the excimer laser (wavelength: 308 nm) is used to irradiate the interface between the supporting substrate (glass) and the polyimide film, the polyimide film having the functional layer can be easily separated from the supporting substrate.

Also, when the polyimide film is peeled from the supporting substrate by the functional layer, the retardation increases when the polyimide film is stretched. Therefore, it is preferable to peel off the polyimide film so that the stress applied to the polyimide film at the time of peeling becomes small. In order to prevent the stretching of the polyimide film, it is necessary to form an anti-stretching layer such as a pressure-sensitive adhesive on the supporting substrate, to form a polyimide layer (film) thereon and further to form a functional layer thereon, It is preferable to separate the protective layer and the functional layer separately and to disperse the stress necessary for peeling in the other layer.

(Example of Production Method of Transparent Polyimide Film)

Hereinafter, the invention of the method for producing a transparent polyimide film will be described in detail based on Examples and Comparative Examples. The present invention is not limited to these examples.

The abbreviations of the raw materials used in Examples and the like are shown below.

TFMB: 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl

M-TB: 2,2'-dimethyl-4,4'-diaminobiphenyl

AAPBZI: 5-Amino-2- (4-aminophenyl) benzoimidazole

AAPBZO: 5-Amino-2- (4-aminophenyl) benzoxazole

CBDA: 1,2,3,4-Cyclobutane tetracarboxylic acid dianhydride

PMDA: pyromellitic dianhydride

BPDA: 3,3 ', 4,4'-biphenyltetracarboxylic acid dianhydride

6FDA: 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane dianhydride

NMP: N-methyl-2-pyrrolidone

The measuring method and the evaluation method of each property in Examples and the like are shown below.

[Light Transmittance and Yellowness Index (YI)]

The light transmittance (T308, T355, T400, T430) of the polyimide film (50 mm x 50 mm, thickness 10 to 15 m) at 308 nm, 355 nm, 400 nm and 430 nm was determined with a SHIMADZU UV-3600 spectrophotometer . The YI (yellowness index) was calculated based on the following equation.

YI = 100 x (1.2879X-1.0592Z) / Y

X, Y and Z are the triplet values of the test specimen and are specified in JIS Z 8722.

[Thermal Expansion Coefficient (CTE)]

A polyimide film having a size of 3 mm x 15 mm was heated to 30 ° C to 280 ° C at a constant temperature raising rate (10 ° / min) while applying a load of 5.0 g by a thermomechanical analysis (TMA) And the thermal expansion coefficient was measured from the elongation (linear expansion) of the polyimide film at the time of temperature lowering.

[Glass transition temperature (Tg)]

The dynamic viscoelasticity when the polyimide film (5 mm x 70 mm) was heated from 23 캜 to 500 캜 at a rate of 5 캜 / min by a dynamic thermomechanical analyzer was measured to determine the glass transition temperature (tan δ maximum value: 캜).

[Pyrolysis temperature (Td1)]

The polyimide film weight of 10 to 20 mg in a nitrogen atmosphere was heated at 30 DEG C to 550 DEG C by a thermogravimetric analysis (TG) apparatus TG / DTA6200 manufactured by Seiko Instruments Inc. , And the temperature at which the weight loss rate was 1% based on the weight at 200 占 폚 was defined as the thermal decomposition temperature (Td1).

[Peelability: LED]

(MJ / cm &lt; ² &gt;) (abbreviation: LED) until the polyimide layer and the support substrate (glass substrate) can be peeled off. The irradiation conditions are the same as the &quot; peelability: laser lift off (LLO) &quot; The higher the energy density, the more difficult it is to peel off. Even if the lifetime of the laser irradiation apparatus is considered, it is preferable that the irradiation energy density is small. The measurement upper limit was 300 mJ / cm &lt; ² &gt;, and when it could not be peeled off at 300 mJ / cm &lt; ² &gt;

[Peelability: laser lift off (LLO)]

A laser beam with a beam size of 14 mm x 1.2 mm, a moving speed of 6 mm / s and a overlap ratio of 80% was irradiated from the side of the supporting substrate (glass) using an excimer laser processing machine (wavelength: 308 nm), and the supporting substrate and the polyimide layer were completely (Separation of the polyimide film from the glass after the perforation line is set one turn after the peeling range is determined by the cutter) is indicated as &quot;? &Quot;, the entire surface or part of the polyimide layer can not be separated Or the state in which the polyimide layer was discolored was designated &quot; X &quot;.

(Synthesis Example 1)

To synthesize the polyimide precursor, 8.57 g of TFMB was dissolved in 85 g of NMP in a 100 ml separable flask under a stream of nitrogen. To this solution, 0.67 g of AAPBZI was added. After stirring for 10 minutes, 5.76 g of CBDA was added. The molar ratio of the diamine component to the tetracarboxylic dianhydride component was 0.99 (substantially equivalent). Thereafter, the solution was stirred at room temperature for 24 hours to carry out a polymerization reaction to obtain a polyamic acid (AA) (a viscous colorless solution) with a high polymerization degree (Mw of 80,000 or more and a viscosity of 5,000 cP or more).

(Synthesis Examples 2 to 18)

A polyamic acid solution was prepared in the same manner as in Synthesis Example 1 except that the diamine and tetracarboxylic dianhydride were changed to the compositions shown in Table 5 and Table 6 to obtain polyamic acid (BB to RR).

Further, in Table 5 and Table 6, the unit of the amount of the diamine and the tetracarboxylic dianhydride is g, and the numerical value in parentheses represents the mol% in the diamine component or the tetracarboxylic acid dianhydride component.

(Example 19)

Solvent NMP was added to the polyimide precursor solution (AA) obtained in Synthesis Example 1 to dilute the solution to a viscosity of 4000 cP. Thereafter, a glass substrate (E-XG manufactured by Corning Incorporated, size = 150 mm x 150 mm, Using a spin coater so that the thickness of the polyimide after curing was about 15 占 퐉. Subsequently, heating was carried out at 100 DEG C for 15 minutes. Then, the temperature was raised from room temperature to 300 占 폚 (360 占 폚 in Comparative Example 18) at a constant temperature raising rate (3 占 폚 / min) in a nitrogen atmosphere, held at 130 占 폚 for 10 minutes in the middle and a 150 mm 占 150 mm polyimide layer (Polyimide (AA)) was formed to obtain a polyimide laminate (AA).

(Examples 20 to 29 and Comparative Examples 15 to 21)

A polyimide laminate (BB to RR) was obtained in the same manner as in Example 19 except that the polyimide precursor (AA) was replaced with any one of the polyimide precursors (BB to RR). The sign of the polyimide precursor and the polyimide laminate correspond to each other and the polyimide laminate (BB) is obtained from the polyimide precursor (BB).

The obtained polyimide laminate (AA to RR) was measured for laser lift off (LLO) and LED. The results are shown in Tables 7 and 8.

For the measurement other than the above, the polyimide film was peeled off from the laminate, but the laminate in this case was prepared in the same manner as above except that a 75 μm-thick polyimide film was used as the substrate instead of the glass substrate. Detailed preparation conditions are shown below.

Solvent NMP was added to the polyamide acid solutions (AA to RR) obtained in Synthesis Examples 1 to 15 to dilute the solution so as to have a viscosity of 3000 cP and then applied onto a polyimide film (Upilex-S) of 75 m. Subsequently, heating was carried out at 100 DEG C for 15 minutes. The temperature was raised from room temperature to 300 占 폚 (360 占 폚 in Comparative Example 18) at a constant temperature raising rate (3 占 폚 / min) in a nitrogen atmosphere, and maintained at 130 占 폚 for 10 minutes in the middle to obtain a polyimide laminated film. Thereafter, the polyimide substrate (Upilex-S) was peeled off and the polyamic acid solution (AA to RR) was imidized to obtain a polyimide film (AA to RR) as a single body. The exfoliation was carried out by separating only the formed polyimide layer with a tweezers from the base material after defining a range of peeling by forming a perforated line with a cutter. The thickness of these films is shown in the item of thickness.

The obtained polyimide films (AA to RR) were subjected to various evaluations such as CTE, light transmittance, YI, Td1 and Tg.

The results are shown in Tables 7 and 8.

Claims (16)

As a polyimide precursor having a structural unit derived from a diamine (structural unit) and a structural unit derived from an acid dianhydride (acid dianhydride)
A structural unit derived from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and a structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride and,
It is preferred that the structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride contains 70 mol% or more of the structural units derived from the total acid dianhydride,
(Light transmittance) when it is imidized to polyimide is not more than 5% at 308 nm, not less than 70% at 400 nm, and has a coefficient of thermal expansion (thermal expansion coefficient) of 45 ppm / K or less Polyimide precursor.
The method according to claim 1,
A polyimide precursor comprising a structural unit derived from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl in an amount of 50 mol% or more in the structural units derived from the whole diamine.
The method according to claim 1,
Contains less than 50 mol% of structural units derived from diamines other than 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl in structural units derived from all diamines, , And a structural unit derived from an acid dianhydride other than 3,4-cyclobutanetetracarboxylic dianhydride is contained in less than 30 mol% in the structural units derived from the total acid dianhydride.
The method of claim 3,
The structural unit derived from an acid dianhydride is preferably a structural unit derived from 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, a structural unit derived from pyromellitic dianhydride, or a structural unit derived from 2,2'-bis ( 3,4-dicarboxyphenyl) hexafluoropropane dianhydride. &Lt; / RTI &gt;
The method of claim 3,
A polyimide precursor, wherein the structural unit derived from a diamine further comprises a structural unit derived from 2,2'-dimethyl-4,4'-diaminobiphenyl.
A polyimide characterized by imidizing the polyimide precursor according to any one of claims 1 to 5.
As the polyimide having a structural unit derived from a diamine and a structural unit derived from an acid dianhydride,
A structural unit derived from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and a structural unit derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride and,
Containing structural units derived from 1,2,3,4-cyclobutane tetracarboxylic dianhydride at 70 mol% or more of the structural units derived from the total acid dianhydride, and
A light transmittance of not more than 5% at 308 nm, not less than 70% at 400 nm, and a thermal expansion coefficient of not more than 45 ppm / K
Features polyimide.
8. The method of claim 7,
Polyimide having a yellow degree of 6 or less.
8. The method of claim 7,
Polyimide for transparent resin substrate material.
A step of applying a polyimide precursor or its resin solution (resin solution) onto the surface of a support body; and a step of heating and imidizing the polyimide precursor or the resin solution to form a support A method for producing a polyimide film, comprising the steps of: forming a polyimide layer on a surface; and removing the polyimide layer from the support to obtain a polyimide film,
Wherein the polyimide precursor is at least one selected from the group consisting of 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and 2,2'-dimethyl-4,4'- Or an acid dianhydride (acid dianhydride) containing 1,2,3,4-cyclobutanetetracarboxylic dianhydride and a diamine containing two kinds of dianhydrides,
The polyimide film has a thermal expansion coefficient of 45 ppm / K or less, a light transmittance of 5% or less at 308 nm, and a light transmittance of 70% or more at 400 nm light, Wherein the transparent polyimide film is a transparent polyimide film.
11. The method of claim 10,
Diamine selected from 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl and 2,2'-dimethyl-4,4'-diaminobiphenyl is used in an amount of 50 mol% or more And further comprising at least 70 mol% of 1,2,3,4-cyclobutane tetracarboxylic dianhydride as the total acid dianhydride.
11. The method of claim 10,
Diamine other than 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl or 2,2'-dimethyl-4,4'-diaminobiphenyl in an amount of 1 to 50 mol% Or an acid dianhydride other than 1,2,3,4-cyclobutanetetracarboxylic dianhydride in an amount of 1 to 30 mol% in the total acid dianhydride.
11. The method of claim 10,
Wherein a yellow degree is 6 or less.
11. The method of claim 10,
Wherein the polyimide layer is peeled from the support by irradiating laser light to an interface between the polyimide layer and the support.
A method for producing a transparent polyimide film according to any one of claims 10 to 14, wherein after the functional layer (functional layer) is formed on the polyimide layer, the polyimide layer having the functional layer is peeled And a step of forming a functional layer on the transparent polyimide film.
16. The method of claim 15,
The functional layer may be any one selected from the group consisting of a transparent conductive layer, a wiring layer, a conductive layer, a gas barrier layer, a thin film transistor, an electrode layer, a light emitting layer, an adhesive layer, a pressure sensitive adhesive layer, a transparent resin layer, Wherein the functional layer is at least two kinds of layers.