JP5428181B2 - Method for producing polyimide precursor and method for producing polyimide using the same - Google Patents

Description

  The present invention relates to a method for producing a polyimide precursor that can be suitably used as an insulating material having high heat resistance and a main component of photosensitive polyimide, and a method for producing a polyimide using the same.

  Polymer materials are used in various products around us because of their easy processing and light weight. The polyimide developed by DuPont in 1955 in the United States has been under development because it has excellent heat resistance and its application to the aerospace field has been studied. Since then, detailed research has been conducted by many researchers, and it has become clear that performance such as heat resistance, dimensional stability, and insulation properties are among the highest in organic materials. Application to materials was promoted. At present, it has been used extensively as a chip coating film in a semiconductor element or as a base material for a flexible printed wiring board.

Polyimide is a polymer synthesized from diamine and acid dianhydride. By reacting diamine and acid dianhydride in a solution, it becomes polyamic acid (polyamic acid) which is a precursor of polyimide, and then becomes a polyimide through a dehydration ring closure reaction. In general, since polyimide has poor solubility in a solvent and is difficult to process, it is often made into a polyimide by making it into a desired shape in a precursor state and then heating. Polyimide precursors are often unstable with respect to heat and water and have poor storage stability.
Polyamic acid is generally synthesized by mixing acid dianhydride and diamine in solution, but the addition reaction consisting of an acid anhydride group and an amino group is a reversible reaction, so the decomposition reaction proceeds in parallel with the addition reaction. doing. Since this addition reaction is an exothermic reaction, polyamic acid is generally stored at a low temperature to suppress a decrease in molecular weight. When the polyamic acid solution contains moisture, the acid anhydride group generated by the reverse reaction with a certain probability reacts with the moisture to become dicarboxylic acid. When dicarboxylic acid is used, the addition reaction with the amino group does not proceed, and the portion is deactivated. Therefore, the molecular weight of polyamic acid decreases with storage. (Non-Patent Document 1)

  In consideration of this point, a polyimide that has been improved so that it can be molded or applied by dissolving in a solvent after introducing a skeleton with excellent solubility in the molecular structure and making it into a polyimide is used. There is a tendency that the chemical resistance and the adhesion to the substrate are inferior to those using a polyimide precursor. Therefore, a method using a polyimide precursor and a method using a solvent-soluble polyimide are selectively used according to the purpose.

Furthermore, a polyimide precursor obtained by esterifying the carboxyl group of polyamic acid has also been proposed. When the carboxyl group is esterified, the reverse reaction does not proceed. Therefore, no decrease in molecular weight is observed, and the storage stability is improved. (Patent Document 1)
However, polyamic acid can be synthesized in one step, whereas polyamic acid ester as in Patent Document 1 is synthesized by synthesizing a dihalf ester compound and then dehydrating using a diamine and a condensing agent such as dicyclohexylcarbodiimide. In order to condense, there exists a subject that it becomes 2 step reaction and the refinement | purification for removing a condensing agent is required, and manufacturing cost starts.
Furthermore, since ester bonds are difficult to thermally decompose, even after imidization from a polyimide precursor to polyimide by a heat treatment at 300 ° C. or higher, ester residue-derived decomposition residues remain, resulting in linear thermal expansion coefficient and humidity expansion. This was a cause of deteriorating polyimide characteristics such as coefficient.

In patent document 2 and patent document 3, after polymerizing polyamic acid which is a polyimide precursor in γ-butyrolactone or a cyclopentanone solvent as a main component of the photosensitive polyimide precursor resin composition, a vinyl ether compound is added to the polymerization solution. A compound obtained by adding and reacting a carboxyl group of polyamic acid with a vinyl ether compound is disclosed.
The above method is a method that can be carried out in one pot from polymerization to reaction with a vinyl ether compound, but it is possible to synthesize using this method such as dissolving in γ-butyrolactone or cyclopentanone. Limited to polyamic acid. Such a soluble polyamic acid has a structural unit that has a high coefficient of linear thermal expansion and a low glass transition temperature. In general, pyromellitic acid exhibiting low linear thermal expansion and high glass transition temperature, and polyamic acid having a structure derived from 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride are effective against γ-butyrolactone and cyclopentanone. Since the solubility is poor and precipitation occurs, the polymerization reaction does not proceed uniformly, and this method has a problem that the target polyimide precursor cannot be obtained.
Polyamic acid, which is a polyimide precursor that usually exhibits low linear thermal expansion and high glass transition temperature, is polymerized with highly soluble amide solvents such as amides such as n-methylpyrrolidone, dimethylacetamide, and dimethylacetamide. ing. However, in these amide solvents, the reaction between polyamic acid and vinyl ether does not proceed with good yield, and the reaction rate is low.

JP 61-293204 A JP 2002-121382 A JP 2001-194784 A Kreuz, J. A., “J Polym Sci Part A: Polym Chem”, 1990, 28, p.3787.

  The present invention has been accomplished in view of the above circumstances, and the purpose thereof is a polyimide that has a skeleton exhibiting low linear thermal expansion and a high glass transition temperature and becomes a polyimide with little residual impurities after imidization. The present invention provides a method for producing a polyimide precursor capable of synthesizing the precursor simply and inexpensively in one pot, and a method for producing a polyimide using the method for producing the polyimide precursor.

The manufacturing method of the polyimide precursor which concerns on this invention is a manufacturing method of the polyimide precursor which superpose | polymerizes 1 or more types of acid dianhydrides and 1 or more types of diamine, Comprising: It superposes | polymerizes in the solution containing a vinyl ether compound. Features.
Polyamic acid, which is a precursor of polyimide having a structure exhibiting high heat resistance and low linear thermal expansion, has poor solubility in non-amide solvents such as γ-butyrolactone and cyclopentanone because of its chemical structure. Since the polymerization reaction does not proceed uniformly, it has been conventionally polymerized with an amide solvent having high solubility. On the other hand, when the hemiacetal esterification of the polyamic acid was carried out in an amide solvent, the reaction rate was poor, so the polymerization of the polyamic acid and the hemiacetal esterification could not be carried out in the same solvent system.
On the other hand, in the present invention, by polymerizing one or more acid dianhydrides and one or more diamines in the presence of a vinyl ether compound, the polymerization is performed in parallel with the polymerization at a relatively low molecular weight stage. Thus, it was possible to obtain a polyimide precursor in one pot without using an amide solvent by performing hemiacetal esterification and proceeding polymerization while improving solubility.

  In the method for producing a polyimide precursor according to the present invention, a state in which the acid dianhydride is dispersed or dissolved in a solution containing the vinyl ether compound is formed, and then the diamine is added and polymerized. From the viewpoint of suppressing side reactions, it is preferable.

  In the method for producing a polyimide precursor according to the present invention, a state in which the acid dianhydride is dispersed or dissolved in a solution containing the vinyl ether compound is formed, and then a solution in which the diamine is dissolved is added. Polymerization is preferable from the viewpoint of suppressing side reactions.

  In the method for producing a polyimide precursor according to the present invention, the solution containing the vinyl ether compound preferably contains one or more solvents selected from lactones and esters from the viewpoints of safety and stability.

  In the manufacturing method of the polyimide precursor which concerns on this invention, it is preferable from a viewpoint which suppresses a side reaction that the solution containing the said vinyl ether compound does not contain active hydrogen other than the said acid dianhydride and the said diamine origin.

  In the manufacturing method of the polyimide precursor which concerns on this invention, it is preferable to react at 0 to 45 degreeC in the solution containing the said vinyl ether compound. When the reaction temperature is less than 0 ° C., the reaction rate is remarkably slow and productivity is deteriorated. Moreover, when it exceeds 45 degreeC, a hemiacetal ester bond thermally decomposes etc., side reactions will occur easily, and a yield will fall.

  In the manufacturing method of the polyimide precursor which concerns on this invention, it is preferable from a viewpoint of suppression of a side reaction that the water content of the solution containing the said vinyl ether compound is 1 weight% or less.

  In the manufacturing method of the polyimide precursor which concerns on this invention, it is preferable to manufacture the polyimide precursor which has a repeating unit represented by following formula (1).

(In Formula (1), R ¹ is a tetravalent organic group, R ² is a divalent organic group, and R ¹ and R ² that are repeated may be the same or different. R ³ and R ⁴ are each independently a monovalent organic group having the structure of the following formula (2), and they may be the same or different, and repeated R ³ and R ⁴ are Each may be the same or different.)

(In the formula (2), R ⁵ , R ⁶ and R ⁷ are each independently hydrogen, a halogen atom, a substituted or unsubstituted alkyl group, an allyl group or an aryl group , and R ⁸ is a group having a hydrocarbon skeleton. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be bonded to each other to show a cyclic structure.

The polyimide precursor having the repeating unit represented by the above formula (1) has a hemiacetal ester structure due to the reaction of the carboxyl group of the polyamic acid with the vinyl ether compound.
The inventor has examined the hemiacetal ester bond of the polyimide precursor in detail, so that the protecting group introduced into the polyimide precursor via the hemiacetal ester bond by the vinyl ether compound has sufficient heat for practical use. It has been found that it has stability and high storage stability, and further, since the hemiacetal ester bond is rapidly decomposed by heating, the imidized polyimide has very little residue of the decomposition product.

The aromatic hemiacetal ester bond obtained from the vinyl ether compound is decomposed into polyamic acid and vinyl ether, acetaldehyde, alcohol or the like by heating at 200 ° C. or lower. These compounds generated by thermal decomposition of the hemiacetal ester bond are often liquid at room temperature having a boiling point of 200 ° C. or less, and most of them are volatilized during the heating process. Furthermore, it is presumed that almost all of the film is dissipated by heating at 250 ° C. or higher required for imidization. Therefore, the finally obtained polyimide film has almost no vinyl ether-derived residue and can be very close to a pure polyimide film.
Thereby, it is possible to obtain a polyimide precursor that becomes a substantially pure polyimide after imidization even though the carboxyl group is protected and stable during storage.

  In the method for producing a polyimide precursor according to the present invention, the weight average molecular weight or the number average molecular weight of the produced polyimide precursor is preferably 2,000 to 1,000,000 from the viewpoint of the mechanical properties of the resulting polyimide film. When the weight average molecular weight or number average molecular weight is less than 2000, the mechanical strength of the resulting polyimide is lowered, and when it is greater than 1000000, the solubility is lowered and it is difficult to obtain a high concentration solution.

In the method for producing a polyimide precursor according to the present invention, a structure in which R ⁵ , R ⁶ and R ⁷ in the formula (2) are hydrogen, that is, a polyimide precursor represented by the following formula (1 ′) is used. It is preferable to manufacture.

(In formula (1 ′), R ¹ , R ² , R ⁸ , R ⁹ and R ¹⁰ are the same as those in formula (1) or formula (2), respectively).

In the method for producing a polyimide precursor according to the present invention, it is preferable from the viewpoint of storage stability that R ⁸ in the formula (2) is an organic group having 2 to 30 carbon atoms and does not contain active hydrogen. .

In the method for producing a polyimide precursor according to the present invention, it is preferable that R ⁸ in the formula (2) contains an ether bond, adhesion to a substrate, storage stability, repellency, volatilization of decomposition products. From the viewpoint of sex.

  In the method for producing a polyimide precursor according to the present invention, it is preferable from the viewpoint of storage stability that the end of the polymer is end-capped with a structure containing no acid anhydride group or active hydrogen. When the amino group or the like having active hydrogen is terminal, decomposition of the hemiacetal ester bond is promoted, and as a result, storage stability may be lowered.

In the method for producing a polyimide precursor according to the present invention, R ¹ in the formula (1) is a skeleton derived from an aromatic tetracarboxylic dianhydride, and a reaction that forms a hemiacetal bond is a catalyst. Since it proceeds promptly at room temperature without using it, it is preferable because synthesis is easy.

In the method for producing a polyimide precursor according to the present invention, it is preferable that 33 mol% or more of R ¹ in the formula (1) has any structure represented by the following formula (3).

The polyimide precursor having the structure as described above is not only a polyimide precursor exhibiting high heat resistance and low linear thermal expansion coefficient, but also has an aromatic carboxylic acid, and thus reacts with a vinyl ether compound at room temperature. It is possible to produce a hemiacetal ester bond. Furthermore, the hemiacetal ester bond obtained from the aromatic carboxylic acid as described above is thermally decomposed by heating at a lower temperature than the hemiacetal ester bond obtained from the aliphatic carboxylic acid. There are few decomposition products derived from the vinyl ether in the polyimide finally decomposed quickly. Therefore, the closer the content of the structure represented by the above formula (3) is to 100 mol% of R ^{1 in} the above formula (1), the easier it is to achieve the object of the present invention. The purpose can be achieved by containing 33% or more of R ^{1 in} (1).

In the method for producing a polyimide precursor according to the present invention, it is preferable that 33 mol% or more of R ² in the formula (1) has any structure represented by the following formula (4).

(R ¹⁰ is a divalent organic group, an oxygen atom, a sulfur atom, or a sulfone group, and R ¹¹ and R ¹² are a monovalent organic group or a halogen atom.)

When it has the above structure, not only the heat resistance of the finally obtained polyimide is improved. Therefore, the closer to 100 mol% of R ² in the formula (1), the easier it is to achieve the target of the present invention, but at least 33% or more of R ² in the formula (1) is contained. You can achieve your goal.

In the method for producing a polyimide precursor according to the present invention, it is preferable that 33 mol% or more of R ² in the formula (1) has any structure represented by the following formula (5).

(A is a natural number of 1 or more, and an amino group is bonded to a meta position or a para position with respect to a bond between benzene rings. R ¹¹ and R ¹² are a monovalent organic group or a halogen atom.)

  When it has the above structure, not only the heat resistance of the finally obtained polyimide is improved, but also a low linear thermal expansion coefficient can be achieved.

  Moreover, the manufacturing method of the polyimide of this invention consists of carrying out dehydration condensation of the polyimide precursor manufactured by the manufacturing method of the polyimide precursor which concerns on the said this invention.

As described above, the method for producing a polyimide precursor of the present invention is a simpler polyimide precursor that has good storage stability and can obtain a polyimide with very little residual impurities after imidization. Can be obtained at low cost.
Moreover, the polyimide manufacturing method of the present invention can obtain a polyimide with very little residual impurities after imidization more easily and at low cost.

The present invention will be described in detail below.
The manufacturing method of the polyimide precursor which concerns on this invention is a manufacturing method of the polyimide precursor which superpose | polymerizes 1 or more types of acid dianhydrides and 1 or more types of diamine, Comprising: It superposes | polymerizes in the solution containing a vinyl ether compound. Features.
Carboxylic acids, particularly aromatic carboxylic acids and vinyl ethers, react when mixed in a non-amide solvent at room temperature to form hemiacetal ester bonds in good yield.
On the other hand, polyamic acid, which is a precursor of polyimide having a structure exhibiting high heat resistance and low linear thermal expansion, is derived from its chemical structure and dissolved in non-amide solvents such as γ-butyrolactone and cyclopentanone. Since the polymerization reaction is poor and the polymerization reaction does not proceed uniformly, conventionally, polymerization of polyamic acid and hemiacetal esterification cannot be performed in the same solvent system.

Therefore, as a result of intensive studies, the inventor has come to find the following method.
The polyamic acid poorly soluble in non-amide solvents is gradually improved in solubility in non-amide solvents as the carboxyl group reacts with the vinyl ether compound and becomes a hemiacetal ester. Is converted into a non-amide solvent that has not been dissolved until then, or a mixed solution of a non-amide solvent and vinyl ether.
Utilizing this phenomenon, when one or more acid dianhydrides and one or more diamines are polymerized in the presence of a vinyl ether compound, the acid dianhydride and the diamine react to form a carboxyl group. Part is precipitated from the solution, but some dissolved reactants react with the carboxyl group and the vinyl ether compound in the solution to form a hemiacetal ester bond, thereby improving the solubility. Then, the deposited amic acid reacts with the vinyl ether compound and gradually dissolves, and when all the amic acid is converted to a hemiacetal ester, all of the amic acid is dissolved.

In general, a polymer having a lower molecular weight often has higher solubility, and a polymer having a repeating unit having a highly polar structure such as a carboxyl group is more likely to be dissolved when dissolved in a low polarity solvent.
In other words, the method of the present invention has a solubility in a non-amide solvent by performing a polymerization reaction while proceeding with a hemiacetal esterification reaction gradually from the stage of a low molecular amic acid having a relatively high solubility. Even in the case of a low chemical structure, a one-pot hemiacetal esterified polyimide precursor can be obtained.

  Examples of the acid dianhydride applicable to the method for producing a polyimide precursor according to the present invention include ethylenetetracarboxylic dianhydride, butanetetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, and cyclopentanetetra. Carboxylic dianhydride, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 3 , 3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 2,2 ′, 6,6′-biphenyltetracarboxylic dianhydride Anhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3 4-dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3 -Dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1,1,1,3,3 3-hexafluoropropane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -1,1,1,3,3,3-hexafluoropropane dianhydride, 1,3-bis [( 3,4-dicarboxy) benzoyl] benzene dianhydride, 1,4-bis [(3,4-dicarboxy) benzoyl] benzene dianhydride, 2,2-bis {4- [4- (1,2 -Dicarboxy) phenoxy] Sulfonyl} propane dianhydride,

2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} propane dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride Bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, 4,4′-bis [4- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, 4,4′-bis [3- (1,2-dicarboxy) phenoxy] biphenyl dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis { 4- [3- (1,2-dicarboxy) phenoxy] phenyl} ketone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfone dianhydride, bis {4- [3- (1,2-dicarbox ) Phenoxy] phenyl} sulfone dianhydride, bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} sulfide dianhydride, bis {4- [3- (1,2-dicarboxy) phenoxy ] Phenyl} sulfide dianhydride, 2,2-bis {4- [4- (1,2-dicarboxy) phenoxy] phenyl} -1,1,1,3,3,3-hexafulpropane dianhydride 2,2-bis {4- [3- (1,2-dicarboxy) phenoxy] phenyl} -1,1,1,3,3,3-propane dianhydride, 2,3,6,7- Naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 1,2,3,4-benzenetetra Carboxylic dianhydride, 3,4,9,10 -Perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride and the like.
These may be used alone or in combination of two or more.

The tetracarboxylic dianhydride preferably used from the viewpoints of the heat resistance, linear thermal expansion coefficient of the finally obtained polyimide film and the reactivity of the protective reaction to the precursor is an aromatic tetracarboxylic dianhydride. It is preferable that there are particularly preferred tetracarboxylic dianhydrides, such as pyromellitic dianhydride, merophanic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3. ', 4,4'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 2,3,2 ', 3'-biphenyltetracarboxylic dianhydride 2,2 ′, 6,6′-biphenyltetracarboxylic dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, 2,2-bis (3,4-dicarboxyphenyl) -1 , 1 1,3,3,3-hexafluoropropane dianhydride and bis (3,4-dicarboxyphenyl) ether dianhydride.
Among these, from the viewpoint of the stability of the hemiacetal ester bond, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride and bis (3,4-dicarboxyphenyl) ether dianhydride are particularly preferred.

  When an acid dianhydride into which fluorine is introduced or an acid dianhydride having an alicyclic skeleton is used as the acid dianhydride to be used in combination, the transparency of the polyimide precursor is improved. In addition, pyromellitic dianhydride, merophanic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride When rigid acid dianhydrides such as 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride are used, it is finally obtained. Since the linear thermal expansion coefficient of the polyimide obtained becomes small, it is preferable. Among these, from the viewpoint of the stability of the hemiacetal ester bond, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,2 ′, 3′-biphenyltetracarboxylic dianhydride is particularly preferred.

  When the acid dianhydride has an alicyclic skeleton, the transparency of the polyimide precursor is improved, so that a highly sensitive photosensitive resin composition is obtained. Furthermore, heating or a catalyst may be required in the reaction for forming the hemiacetal ester bond, but since it is possible to form a hemiacetal ester bond having a relatively high stability, emphasis is placed on storage stability. The case is preferred.

  On the other hand, when aromatic tetracarboxylic dianhydride is used, it becomes the photosensitive resin composition which is excellent in heat resistance and shows a low linear thermal expansion coefficient. Furthermore, since the reaction for forming a hemiacetal ester bond proceeds at room temperature, the target polyimide precursor can be obtained very easily. Furthermore, since it decomposes at a lower temperature, there is an advantage that the decomposition product hardly remains in the film after imidization.

Next, the diamine component applicable to the manufacturing method of the polyimide precursor of this invention can also be used individually by 1 type of diamine, or using together 2 or more types of diamine. The diamine component used is not limited, but p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 4,4′-diamino. Diphenyl ether, 3,3′-diaminodiphenyl sulfide, 3,4′-diaminodiphenyl sulfide, 4,4′-diaminodiphenyl sulfide, 3,3′-diaminodiphenyl sulfone, 3,4′-diaminodiphenyl sulfone, 4,4 '-Diaminodiphenylsulfone, 3,3'-diaminobenzophenone, 4,4'-diaminobenzophenone,
3,4′-diaminobenzophenone, 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 2,2-di (3-aminophenyl) propane, 2,2-di (4-aminophenyl) propane, 2- (3-aminophenyl) -2- (4-aminophenyl) propane, 2,2-di (3-aminophenyl) -1,1,1,3,3,3 -Hexafluoropropane, 2,2-di (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2- (3-aminophenyl) -2- (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 1,1-di (3-aminophenyl) -1-phenylethane, 1,1-di (4-aminophenyl) -1-phenylethane , 1- ( 3-aminophenyl) -1- (4-aminophenyl) -1-phenylethane, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4- Bis (3-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminobenzoyl) benzene, 1,3-bis (4-aminobenzoyl) benzene, 1, 4-bis (3-aminobenzoyl) benzene, 1,4-bis (4-aminobenzoyl) benzene, 1,3-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,3-bis (4 -Amino-α, α-dimethylbenzyl) benzene, 1,4-bis (3-amino-α, α-dimethylbenzyl) benzene, 1,4-bis (4-amino-α, α-dimethylbenzyl) L) benzene, 1,3-bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,3-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4- Bis (3-amino-α, α-ditrifluoromethylbenzyl) benzene, 1,4-bis (4-amino-α, α-ditrifluoromethylbenzyl) benzene, 2,6-bis (3-aminophenoxy) benzo Nitrile, 2,6-bis (3-aminophenoxy) pyridine, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, bis [4- (3- Aminophenoxy) phenyl] ketone, bis [4- (4-aminophenoxy) phenyl] ketone, bis [4- (3-aminophenoxy) phenyl] sulfide, bis [ - (4-aminophenoxy) phenyl] sulfide,

Bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-amino) Phenoxy) phenyl] ether, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3 3,3-hexafluoropropane, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (4-aminophenoxy) benzoyl] ben 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,4-bis [4- (4-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-amino Phenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (3-aminophenoxy) -Α, α-dimethylbenzyl] benzene, 1,4-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 4,4'-bis [4- (4-aminophenoxy) benzoyl ] Diphenyl ether, 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone, 4,4′-bis [4- (4-amino-α, α-dimethylbenzen) ) Phenoxy] diphenylsulfone, 4,4′-bis [4- (4-aminophenoxy) phenoxy] diphenylsulfone, 3,3′-diamino-4,4′-diphenoxybenzophenone, 3,3′-diamino-4 , 4′-Dibiphenoxybenzophenone, 3,3′-diamino-4-phenoxybenzophenone, 3,3′-diamino-4-biphenoxybenzophenone, 6,6′-bis (3-aminophenoxy) -3,3 3 ′, 3′-tetramethyl-1,1′-spirobiindane, 6,6′-bis (4-aminophenoxy) -3,3,3 ′, 3′-tetramethyl-1,1′-spirobiindane, , 3-bis (3-aminopropyl) tetramethyldisiloxane, 1,3-bis (4-aminobutyl) tetramethyldisiloxane, α, ω-bis ( -Aminopropyl) polydimethylsiloxane, α, ω-bis (3-aminobutyl) polydimethylsiloxane, bis (aminomethyl) ether, bis (2-aminoethyl) ether, bis (3-aminopropyl) ether, bis ( 2-aminomethoxy) ethyl] ether, bis [2- (2-aminoethoxy) ethyl] ether, bis [2- (3-aminoprotoxy) ethyl] ether,

1,2-bis (aminomethoxy) ethane, 1,2-bis (2-aminoethoxy) ethane,
1,2-bis [2- (aminomethoxy) ethoxy] ethane, 1,2-bis [2- (2-aminoethoxy) ethoxy] ethane, ethylene glycol bis (3-aminopropyl) ether, diethylene glycol bis (3- Aminopropyl) ether, triethylene glycol bis (3-aminopropyl) ether, ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7 -Diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,2-diaminocyclohexane, 1,3-diamino Cyclohexane, 1,4-diaminocyclohexane, 1,2-di 2-aminoethyl) cyclohexane, 1,3-di (2-aminoethyl) cyclohexane, 1,4-di (2-aminoethyl) cyclohexane, bis (4-aminocyclohexyl) methane, 2,6-bis ( Aminomethyl) bicyclo [2.2.1] heptane, 2,5-bis (aminomethyl) bicyclo [2.2.1] heptane, and some or all of the hydrogen atoms on the aromatic ring of the diamine are fluoro groups. A diamine substituted with a substituent selected from a methyl group, a methoxy group, a trifluoromethyl group, or a trifluoromethoxy group can also be used.
Furthermore, depending on the purpose, any one or two or more of the ethynyl group, benzocyclobuten-4′-yl group, vinyl group, allyl group, cyano group, isocyanate group, and isopropenyl group serving as a crosslinking point, Even if it introduce | transduces into some or all of the hydrogen atoms on the aromatic ring of diamine as a substituent, it can be used.

The diamine can be selected depending on the desired physical properties. If a rigid diamine such as p-phenylenediamine is used, the finally obtained polyimide has a low expansion coefficient. Rigid diamines include p-phenylenediamine, m-phenylenediamine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2, 6 as diamines in which two amino groups are bonded to the same aromatic ring. -Diaminonaphthalene, 2,7-diaminonaphthalene, 1,4-diaminoanthracene and the like can be mentioned.
In addition, diamines in which two or more aromatic rings are bonded by a single bond, and two or more amino groups are each bonded directly or as part of a substituent on a separate aromatic ring, for example, There exists what is represented by following formula (6). Specific examples include benzidine and the like.

(A is a natural number of 1 or more, and an amino group is bonded to a meta position or a para position with respect to a bond between benzene rings. R ¹¹ and R ¹² are a monovalent organic group or a halogen atom.)

Furthermore, in the above formula (6), a diamine having a substituent at a position where the amino group on the benzene ring is not substituted and which does not participate in the bond with another benzene ring can also be used. These substituents are monovalent organic groups, but they may be bonded to each other.
Specific examples include 2,2′-dimethyl-4,4′-diaminobiphenyl, 2,2′-ditrifluoromethyl-4,4′-diaminobiphenyl, 3,3′-dichloro-4,4′-diamino. Biphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-diaminobiphenyl and the like can be mentioned.
When the finally obtained polyimide is used as an optical waveguide or an optical circuit component, the transmittance for electromagnetic waves having a wavelength of 1 μm or more can be improved by introducing fluorine as a substituent of the aromatic ring.

  On the other hand, when a diamine having a siloxane skeleton such as 1,3-bis (3-aminopropyl) tetramethyldisiloxane is used as the diamine, the elastic modulus of the finally obtained polyimide is lowered and the glass transition temperature is lowered. be able to.

  Here, the selected diamine is preferably an aromatic diamine from the viewpoint of heat resistance. However, depending on the desired physical properties, the diamine may be an aliphatic diamine or siloxane within a range not exceeding 60 mol%, preferably not exceeding 40 mol%. Non-aromatic diamines such as diamines may be used.

The production method of the present invention can achieve the object if the reaction solution contains a vinyl ether compound in addition to the acid dianhydride and diamine to be polymerized. Depending on the purpose, all of the reaction solvent may be a vinyl ether compound, or depending on the solubility of the solute, the reaction solvent may be a mixture of a vinyl ether compound and a solvent other than the vinyl ether compound.
The content of vinyl ether is preferably 1% by weight to 100% by weight with respect to the whole reaction solvent (total weight of liquid components in the reaction solution, excluding substances solid at 25 ° C. such as diamine and acid anhydride), and 5% by weight. -100% by weight is more preferable, and 10% by weight to 100% by weight is more preferable. In particular, when the vinyl ether compound contains a solvent other than the vinyl ether compound, the vinyl ether compound is preferably contained in an amount of 55 parts by weight or more with respect to 100 parts by weight of the solvent other than the vinyl ether compound from the viewpoint of the reaction rate of the polyimide precursor. .

  The reaction between the carboxyl group derived from the acid dianhydride and the vinyl ether compound proceeds as follows, and a hemiacetal ester bond represented by the following formula (7) is formed.

(In formula (7), R ⁵ , R ⁶ and R ⁷ are each independently hydrogen, a halogen atom or a monovalent organic group, and R ⁸ is a monovalent organic group. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be bonded to each other to show a cyclic structure.)

R ⁵ , R ⁶ and R ⁷ are preferably hydrogen or a substituted or unsubstituted alkyl group, allyl group or aryl group. In particular, hydrogen is preferable because of easy availability of raw materials. Further, it is preferable not to include a primary, secondary, or tertiary amino group, or a substituent having an active hydrogen such as a hydroxyl group.
The substituent having active hydrogen in this case is a substituent that can exchange with a hemiacetal ester bond, and specifically includes a hydroxyl group, a primary amino group, a secondary amino group, a carboxyl group, a mercapto group, and the like. (Chemical Dictionary Tokyo Chemical Doujin)

R ^{8 in the} above formula (7) is a monovalent organic group having 1 or more carbon atoms. R ⁸ is exemplified by a group having a hydrocarbon skeleton. They may contain bonds or substituents other than hydrocarbons such as heteroatoms, or such heteroatoms may be incorporated into an aromatic ring to form a heterocycle. Examples of the group having a hydrocarbon skeleton include a linear or branched or alicyclic saturated or unsaturated hydrocarbon group, a linear or branched saturated or unsaturated halogenated alkyl group, or phenyl and naphthyl. And further a group containing an ether bond in a linear or branched saturated or unsaturated hydrocarbon skeleton (for example, — (R—O) _n —R ′, where R and R ′ Is a substituted or unsubstituted saturated or unsaturated hydrocarbon, n is an integer greater than or equal to 1; -R ″-(O—R ″ ′) _m , where R ″ and R ″ ′ are substituted or unsubstituted saturated or unsaturated Saturated hydrocarbon, m is an integer of 1 or more,-(O-R "') _m is bonded to a carbon different from the terminal of R"; and the like), linear or branched saturated or A group containing a thioether bond in an unsaturated hydrocarbon skeleton, linear or branched, saturated or unsaturated Halogen atoms on the hydrocarbon backbone, a cyano group, a silyl group, a nitro group, an acetyl group, an acetoxy group, and a variety of groups groups containing formed by bonding a heteroatom or heteroatoms such as a sulfonic group.

When a primary, secondary, or tertiary amino group, or a substituent having an active hydrogen such as a hydroxyl group is included, the hemiacetal ester bond is easily decomposed, so that the storage stability is lowered. Therefore, the above formula (7) R ⁸ preferably contains no active hydrogen.
Furthermore, when R ⁸ in the above formula (7) contains a reactive ethylenic unsaturated bond, the storage stability of the polyimide precursor tends to deteriorate. Therefore, even if it contains a reactive unsaturated bond, a small amount is preferable, and a repeating unit containing a reactive unsaturated bond in R ⁸ of the above formula (7) is obtained. It is preferable that it is 35 mol% or less in all the repeating units of a polyimide precursor. Meanwhile, the the terms which hardly remain in the polyimide film decomposition of R ⁸ after hemiacetal ester bond is cleaved, unsaturated bonds having reactivity to R ⁸ in the formula (7) does not contain It is preferable.

R ^{8 in the} above formula (7) preferably contains an ether bond in the hydrocarbon skeleton from the viewpoints of adhesion to the substrate, storage stability, repellency, and decomposition product volatility. It may contain a polyoxyalkylene skeleton. When the polyoxyalkylene skeleton is included, the number of repeating oxyalkylenes is preferably 15 or less from the viewpoint of the volatility of the decomposition product.

The hemiacetal ester bond is decomposed by heating into carboxylic acid and other products, and the decomposition temperature is generally determined by the carbon atom bonded to the oxygen atom in R ⁸ in the above formula being a tertiary carbon <secondary carbon < Higher in order of primary carbon substituents.
On the other hand, the reaction of a vinyl ether compound and a carboxylic acid to obtain a hemiacetal ester bond generally involves the reaction of a substituent of primary carbon <secondary carbon <tertiary carbon in R ⁸ in the above formula with the carbon bonded to the oxygen atom. High reaction rate in order.

Accordingly, in R ⁸ of the above formula (7), when the carbon bonded to the oxygen atom is a primary carbon, the polyimide precursor has high stability and can withstand long-term storage. Furthermore, since the heating temperature during the process such as film formation can be set higher, the stability during the process is improved.
In R ⁸ of the above formula (7), when the carbon bonded to the oxygen atom is a tertiary carbon, the hemiacetal ester bond is decomposed by heating at a lower temperature, although the polyimide precursor becomes slightly unstable. Therefore, in the process of heating for imidization, the hemiacetal ester bond is more smoothly decomposed and the decomposed product is volatilized, and the protective group in the polyimide film finally obtained even in shorter time heating The amount of residual components of the decomposition product of the above can be reduced, and in many cases can be substantially zero. Moreover, when it is desired to obtain a polyimide precursor having a hemiacetal ester bond in a short reaction time, R ⁸ is preferably a tertiary substituent.
In R ⁸ of the above formula (7), when the carbon bonded to the oxygen atom is a secondary carbon, it exhibits the characteristics between the case of the primary carbon and the case of the tertiary carbon, and the storage stability of the polyimide precursor In addition, it is possible to obtain a photosensitive resin composition having a good balance between the releasability of the protecting group and the reactivity to the hemiacetal ester bond.

R ⁸ in the formula (7) preferably has 2 to 30 carbon atoms from the viewpoint of the volatility of the decomposition product, and more preferably 2 to 15 carbon atoms.

A particularly preferred combination in the structure of R ⁸ in the formula (7) is that the carbon bonded to the oxygen atom is a primary carbon or a secondary carbon, and further, in a linear, branched or cyclic saturated hydrocarbon skeleton. A structure containing one or more ether bonds and no active hydrogen.

R ⁸ in the formula (7) is not particularly limited, and examples thereof include a methyl group, an ethyl group, an ethynyl group, a propyl group, an isopropyl group, an n-butyl group, a t-butyl group, an n-hexyl group, and a cyclohexyl group. Cyclohexylmethyl group, methoxyethyl group, ethoxyethyl group, propoxyethyl group, butoxyethyl group, cyclohexyloxyethyl group, methoxypropyl group, ethoxypropyl group, propoxypropyl group, butoxypropyl group, cyclohexyloxypropyl group, etc. It is done.

The vinyl ether compound is appropriately selected and used according to the desired structure of the hemiacetal ester bond. For example, specifically, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, sec-butyl vinyl ether, tert-butyl vinyl ether, tert-amyl vinyl ether, 2-ethylhexyl vinyl ether, octadecyl vinyl ether Vinyl ether compounds having a linear or branched saturated or unsaturated hydrocarbon skeleton, such as cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, tricyclodecanyl vinyl ether, tricyclodecanyl methyl vinyl ether, pentacyclopentadecanyl vinyl ether, pentacyclo Contains an alicyclic saturated hydrocarbon skeleton such as pentadecanyl methyl vinyl ether Nyl ether compounds; ethylene glycol methyl vinyl ether, ethylene glycol ethyl vinyl ether, ethylene glycol propyl vinyl ether, ethylene glycol butyl vinyl ether, polyethylene glycol methyl vinyl ether, polyethylene glycol ethyl vinyl ether, polyethylene glycol propyl vinyl ether, polyethylene glycol butyl vinyl ether, polyethylene glycol octyl vinyl ether, propylene glycol Methyl vinyl ether, propylene glycol ethyl vinyl ether, propylene glycol propyl vinyl ether, propylene glycol butyl vinyl ether, polypropylene glycol methyl vinyl ether, polypropylene glycol ethyl vinyl ether , Polypropylene glycol propyl vinyl ether, polypropylene glycol butyl vinyl ether, polypropylene glycol octyl vinyl ether, butylene glycol methyl vinyl ether, butylene glycol ethyl vinyl ether, butylene glycol propyl vinyl ether, butylene glycol butyl vinyl ether, polybutylene glycol methyl vinyl ether, polybutylene glycol ethyl vinyl ether, polybutylene Examples thereof include vinyl ethers containing an ether bond in a linear or branched saturated or unsaturated hydrocarbon skeleton such as glycol propyl vinyl ether, polybutylene glycol butyl vinyl ether, and polybutylene glycol octyl vinyl ether.
Of the above vinyl ether compounds, when the polyoxyalkylene residue is included, the number of repeating alkylene residues is preferably 15 or less from the viewpoint of volatility after decomposition.

  Examples of general-purpose solvents that can be used as solvents other than vinyl ether compounds include ethers such as diethyl ether, tetrahydrofuran, dioxane, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether; methyl ethyl ketone, acetone, methyl Ketones such as isobutyl ketone, cyclopentanone, cyclohexanone; ethyl acetate, butyl acetate, n-propyl acetate, i-propyl acetate, n-butyl acetate, i-butyl acetate, acetate esters of the glycol monoethers (for example, Methyl cellosolve acetate, ethyl cellosolve acetate), methoxypropyl acetate, ethoxypropyl acetate, dimethyl oxalate, lactic acid Esters such as ethyl and lactate; methylene chloride, 1,1-dichloroethane, 1,2-dichloroethylene, 1-chloropropane, 1-chlorobutane, 1-chloropentane, chlorobenzene, bromobenzene, o-dichlorobenzene, m-di Halogenated hydrocarbons such as chlorobenzene; Lactones such as γ-butyrolactone; Sulphoxides such as dimethyl sulfoxide; Other organic polar solvents; and further aromatic hydrocarbons such as benzene, toluene and xylene , And other organic nonpolar solvents. These solvents are used alone or in combination.

Among these, in the method for producing a polyimide precursor of the present invention, the solution containing the vinyl ether compound preferably contains one or more solvents selected from lactones and esters.
Since the yield of the hemiacetal esterification reaction is low in an amide solvent, it is preferable to use a non-amide solvent. As a result of intensive studies, the inventor found that the aromatic carboxylic acid and the vinyl ether compound can be obtained only by stirring at room temperature. At that time, under dehydration conditions, nitrogen atoms such as lactones and sulfoxides were obtained. It is possible to dramatically improve the reaction yield of the carboxyl group and the vinyl ether compound by using a solvent that does not contain benzene, and to produce a polyimide precursor in which the carboxyl group of the polyamic acid is completely a hemiacetal ester bond It has become possible.
As non-amide solvents that may dissolve polyimide precursors such as polyamic acid, lactones containing ester bonds such as γ-butyrolactone and sulfoxide solvents such as dimethyl sulfoxide are known. While dimethyl sulfoxide has high solubility, it is difficult to be oxidized and mutagenicity has been confirmed, so there are problems in stability and safety as a solvent. On the other hand, esters and lactones are often poorer in solubility than dimethyl sulfoxide, but mutagenicity has not been confirmed and is highly safe. Moreover, since the solubility with respect to ester, especially lactones will improve when the carboxyl group of polyamic acid is made into a hemiacetal ester, it becomes possible to adjust a solution having a practically sufficient concentration.

Examples of lactones include γ-butyrolactone, α-acetyl-γ-butyrolactone, ε-caprolactone, γ-hexanolactone, and δ-hexanolactone. Examples of sulfoxides include dimethyl sulfoxide, methyl ethyl sulfoxide, and diethyl. Examples thereof include sulfoxide.
Esters include ethyl acetate, propyl acetate, butyl acetate, ethyl propionate, propyl propionate, butyl propionate, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether Examples include acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, and the like.

In the method for producing a polyimide precursor of the present invention, the solution containing the vinyl ether compound preferably contains no active hydrogen other than the acid dianhydride and the diamine.
According to the inventor's examination results, the reaction is carried out in a solvent having an active hydrogen such as an amino group or a hydroxyl group or in the presence of a compound having an active hydrogen such as an amino group or a hydroxyl group in the form of a hemiacetal. The yield of obtaining the ester bond tended to be low. In addition, when using a solvent containing a nitrogen atom in a form other than a nitro group in the skeleton, the yield was low, so the case where the skeleton contains a solvent containing a nitrogen atom in a form other than a nitro group may also be included. It is not preferable.
The hemiacetal ester bond is decomposed by a compound having an active hydrogen such as a hydroxyl group or an amino group. Therefore, it is ideal that there is no compound having an active hydrogen other than a carboxyl group in the reaction solution in a shorter time. Reaction progresses.

In the method for producing a polyimide precursor of the present invention, it is particularly preferable that the solution containing the vinyl ether compound does not contain water. When a hemiacetal ester bond coexists with a compound having active hydrogen such as a hydroxyl group, an exchange reaction with them may occur. Since hemiacetal bonds are usually more stable than hemiacetal ester bonds, when a hydroxyl group-containing compound coexists, hemiacetal ester bonds are consumed by hydroxyl groups and carboxylic acid is produced. The rate of the decomposition reaction of the hemiacetal ester bond varies depending on its chemical structure, and the higher the rate of the reaction that forms the hemiacetal ester bond, the higher the decomposition rate.
The water content in the solution containing the vinyl ether compound is preferably 1% by weight or less, and more preferably 0.1% by weight or less. Furthermore, it is most preferable that it does not contain water substantially. Here, “substantially free of water” means that the content of water in the solution containing the vinyl ether compound is so small that no decrease in reaction yield due to water is observed. Specifically, it refers to a state in which the water content in the solution containing the vinyl ether compound is less than about 0.005% by weight, and further less than 0.001% by weight.

  In the method for producing a polyimide precursor of the present invention, the order of addition is not particularly limited as long as one or more acid dianhydrides and one or more diamines are polymerized in a solution containing a vinyl ether compound. It is appropriately selected in consideration of the solubility of the solvent to be mixed and the solute.

In the method for producing a polyimide precursor of the present invention, the acid dianhydride is dispersed or dissolved in a solution containing the vinyl ether compound, and then the diamine is added, or the diamine is added. It is preferable to polymerize by adding a dissolved solution. By doing in this way, since the time which an amino group exists in a reaction solution can be shortened, more nearly ideal reaction advances.
Since the amidation reaction using an acid anhydride and an amino group has a relatively high reaction rate, the amidation reaction proceeds promptly when diamine is added. When the amount of the diamine in the reaction solution is smaller than the amount of the acid dianhydride, the terminal of the amic acid generated by the reaction is an acid anhydride group, which is preferable because the hemiacetal ester bond does not decompose.

In general, acid dianhydride has low solubility, and in a non-amide solvent, the reaction with diamine can be carried out in a solution with slightly dissolved acid dianhydride or in a dispersed solid state. This is a solid-liquid reaction between the acid dianhydride and the diamine solution.
When a diamine is added according to the above procedure, an amic acid is generated and often precipitates from the reaction solution.
Thereafter, the precipitated amic acid is gradually converted into a hemiacetal ester by the vinyl ether compound in the reaction solution, so that it is dissolved in the reaction solution and polymerization is presumed to proceed gradually.

  The method of adding diamine in the case of adding diamine or diamine solution later is not particularly limited, but if the entire required amount is added at once, the temperature of the reaction solution may increase due to reaction heat, It is preferable to add gradually over time or to divide and add several times.

  Since the hemiacetal esterification reaction is very sensitive to moisture, it is preferable to carry out the reaction by a technique that can prevent the mixing of moisture as much as possible. For that purpose, rather than adding diamine that is in a solid state from the opening of the reaction vessel, it is possible to prevent water from mixing more by dissolving it in a previously dehydrated solvent and dropping it in the state of a solution. Is preferable because the amount added is easy to control.

The concentration of the diamine in the diamine solution when the diamine solution is added later is appropriately selected, but is preferably in the range of 0.1% by weight to 50% by weight, and more preferably in the range of 1% by weight to 40% by weight. preferable.
When the concentration of diamine is less than 0.1% by weight, the concentration of the reaction solution may be diluted to lower the reaction rate, or a high molecular weight polyimide precursor may not be obtained. When the concentration exceeds 50% by weight, there is a problem that it is difficult to delicately control the addition amount.

In the method for producing a polyimide precursor of the present invention, a state in which a diamine is dispersed or dissolved in a solution containing a vinyl ether compound is formed, and then an acid dianhydride and other components are added and polymerized. Also good.
As described above, in order to proceed the ideal reaction, the method of adding diamine later is preferable, but in the case of a reaction system containing an excessive amount of vinyl ether compound, acid dianhydride is added to the diamine solution. In this method, a polyimide precursor can be obtained for the purpose.
Even if the hemiacetal ester bond is decomposed by the amino group of the diamine, if the vinyl ether compound is excessively present, the hemiacetal ester bond is immediately regenerated. In addition, in many cases, the diamine reacts with the acid dianhydride to lower the solubility and precipitate from the reaction solution. Therefore, after the acid dianhydride is added in a certain amount or more, the concentration of the diamine in the reaction solution. Is extremely lowered, and it is possible to obtain a polyimide precursor in a range that is not problematic in practice.

  The method for adding acid dianhydride is not particularly limited, but if the entire required amount is added at once, the temperature of the reaction solution may increase due to the heat of reaction. Alternatively, it is preferable to divide and add several times.

  In the manufacturing method of the polyimide precursor of this invention, it is preferable to react at 0 degreeC-45 degreeC in the solution containing the said vinyl ether compound, Furthermore, 5-35 degreeC is preferable, and also 10-30 degreeC is preferable. The reaction here is a hemiacetal esterification reaction and a polymerization reaction between an acid dianhydride and a diamine. When the reaction temperature is less than 0 ° C., the reaction rate is remarkably slow and productivity is deteriorated. Moreover, when it exceeds 45 degreeC, a hemiacetal ester bond thermally decomposes etc., side reactions will occur easily, and a yield and a protection rate will fall.

The polyimide precursor obtained by the production method of the present invention preferably has a weight average molecular weight or a number average molecular weight of 2000 to 1000000. The range of 3,000 to 700,000 is more preferable, and the range of 5,000 to 100,000 is more preferable.
When the average molecular weight is less than 2000, the mechanical strength of the finally obtained polyimide is lowered. When the average molecular weight is larger than 1,000,000, there is a problem that the solubility is lowered and a high-concentration solution cannot be obtained, and the viscosity of the solution is increased to deteriorate the processing suitability.
The average molecular weight in this case is a molecular weight obtained by a known method, and means either a weight average molecular weight or a number average molecular weight. The weight average molecular weight is exemplified by a value in terms of polystyrene by gel permeation chromatography (GPC), and the number average molecular weight is derived from a peak derived from the repeating unit at the terminal portion and a repeating unit derived from the non-terminal repeating unit determined from the ¹ H-NMR spectrum. Examples are a method of obtaining from the peak integration ratio.

  In the manufacturing method of the polyimide precursor which concerns on this invention, it is preferable to manufacture the polyimide precursor which has a repeating unit represented by following formula (1).

(In Formula (1), R ¹ is a tetravalent organic group, R ² is a divalent organic group, and R ¹ and R ² that are repeated may be the same or different. R ³ and R ⁴ are each independently a monovalent organic group having the structure of the following formula (2), and they may be the same or different, and repeated R ³ and R ⁴ are Each may be the same or different.)

(In formula (2), R ⁵ , R ⁶ and R ⁷ are each independently hydrogen, a halogen atom or a monovalent organic group, and R ⁸ is a monovalent organic group. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be bonded to each other to show a cyclic structure.)

The present inventor easily cleaves by heating to generate a carboxyl group for the purpose of obtaining a polyimide precursor that has little residue derived from a protective component of the carboxyl group after imidization and has good storage stability at room temperature. The following findings were obtained when research was conducted focusing on the hemiacetal ester bond.
It is known that polyamic acid, which is a precursor of polyimide, is generally easily hydrolyzed at room temperature, resulting in a decrease in molecular weight. This is said to be derived from the fact that the polyaddition reaction for obtaining a polyamic acid is an equilibrium reaction. In other words, the amide bond of the polyamic acid is constantly cleaved or recombined into an acid anhydride and an amino group. When the acid anhydride group contained in the system reacts with moisture in the system to form dicarboxylic acid, the acid anhydride group deviates from the above equilibrium reaction system, and the amide bond is broken (the molecular weight of the polyamic acid decreases). It is said that the balance moves in the direction.
For this reason, the polyamic acid ester, which is also a polyimide precursor, is esterified with a carboxylic acid, so that the reverse reaction that breaks the molecular chain does not proceed and the molecular weight does not decrease.

  From these findings, the inventor imparts storage stability by esterifying the carboxyl group of the polyamic acid to a hemiacetal ester, while the hemiacetal ester bond is thermally decomposed to polyamic acid in the course of heating accompanying imidization. Returning, the inventors thought that if the carboxyl group-protecting component volatilizes, a polyimide having no residue derived from the carboxyl group-protecting component in the film could be created, and earnestly studied to arrive at the present invention.

  In particular, the hemiacetal ester bond is easily pyrolyzed only by heating as compared with the ester bond, so that the bond is broken by heating at a lower temperature. Many polyimide precursors are generally said to undergo imidization gradually from a temperature in the vicinity of 140 ° C. with heating, and the glass transition temperature (Tg) of the film increases as the imidization rate increases. To go. When Tg increases, the vibration of the molecular chain is suppressed, so that it is difficult to volatilize the substance from the inside of the film. On the other hand, in the case of a hemiacetal ester bond, since it decomposes from around room temperature in some cases, the decomposition reaction occurs with a low imidation rate. Therefore, when a hemiacetal ester bond is combined with the polyimide precursor, the volatility of the decomposition component is good, and the decomposition component volatilizes in the process of heating when converting the polyimide precursor to polyimide, and in the polyimide film It has a feature that there is almost no degradation product derived from the remaining hemiacetal ester binding site.

From the above, the site (hereinafter referred to as a protected site) that is bonded to the polyimide precursor main chain by the hemiacetal ester bond in the present invention and is to be removed later has a low molecular weight, and the structure has volatility after decomposition. A higher value is preferable from the viewpoint of suppressing the decomposition product from remaining on the polyimide film.
Furthermore, when the protected site R ⁸ contains a reactive ethylenic unsaturated bond, the storage stability tends to be poor. Therefore, even if it contains a reactive unsaturated bond, a small amount is preferable, and the repeating unit containing a reactive unsaturated bond in R ⁸ of the above formula (2) is represented by the formula ( It is preferable that it is 35 mol% or less in all the repeating units represented by 1). Meanwhile, the the terms which hardly remain in the polyimide film decomposition of R ⁸ after hemiacetal ester bond is cleaved, unsaturated bonds having reactivity to R ⁸ in the formula (2) does not contain It is preferable.

In the polyimide precursor, it is preferable that 33 mol% or more of R ¹ in the formula (1) has any structure represented by the following formula (3).

The polyimide precursor having the structure as described above is not only a polyimide precursor exhibiting high heat resistance and low linear thermal expansion coefficient, but also has an aromatic carboxylic acid. Is carried out with good yield, and a hemiacetal ester bond is formed. Furthermore, the hemiacetal ester bond obtained from the aromatic carboxylic acid as described above is thermally decomposed by heating at a lower temperature than the hemiacetal ester bond obtained from the aliphatic carboxylic acid. There are few decomposition products derived from the vinyl ether in the polyimide finally decomposed quickly. Therefore, the closer the content of the structure represented by the above formula (3) is to 100 mol% of R ^{1 in} the above formula (1), the easier it is to achieve the object of the present invention. The purpose can be achieved by containing 33% or more of R ^{1 in} (1). Among them, the content of the structure represented by the above formula (3) is preferably 50 mol% or more, and more preferably 70 mol% or more of R ¹ in the formula (1).

Moreover, in the said polyimide precursor, it is preferable that 33 mol% or more among R < ² > in said Formula (1) is one of the structures represented by following formula (4).

(R ¹⁰ is a divalent organic group, an oxygen atom, a sulfur atom, or a sulfone group, and R ¹¹ and R ¹² are a monovalent organic group or a halogen atom.)

When it has the above structure, the heat resistance of the polyimide finally obtained improves. Therefore, the closer the content of the structure represented by the above formula (4) is to 100 mol% of R ² in the formula (1), the easier it is to achieve the target of the present invention. If at least 33% or more of R ^{2 in} (1) is contained, the object can be achieved. Of these the content of the structure represented by the above formula (4) is preferably the at formula (1) 50 mol% or more of R ² in, it is more preferably 70 mol% or more.

Especially, in the said polyimide precursor, it is preferable that 33 mol% or more among R < ² > in the said Formula (1) is a structure represented by following formula (5).

(A is a natural number of 1 or more, and an amino group is bonded to a meta position or a para position with respect to a bond between benzene rings. R ¹¹ and R ¹² are a monovalent organic group or a halogen atom.)

When it has the above structure, not only the heat resistance of the polyimide finally obtained improves but also a low linear thermal expansion coefficient can be achieved. Therefore, the closer the content of the structure represented by the formula (5) is to 100 mol% of R ² in the formula (1), the easier it is to achieve the target of the present invention. If at least 33% or more of R ^{2 in} (1) is contained, the object can be achieved. Of these the content of the structure represented by the above formula (5) is preferably the at formula (1) 50 mol% or more of R ² in, it is more preferably 70 mol% or more.

In the formula (1), R ³ and R ⁴ are each independently a monovalent organic group having the structure of the above formula (2), and they may be the same or different and are repeated R ³ and R ⁴ may be the same or different. ^{R 5, R 6, R 7} , R 8 in the formula (2), since it is preferable is the same as ^{R 5, R 6, R 7} , R 8 in the above-mentioned formula (7) above, here Description is omitted.

Moreover, in the manufacturing method of the polyimide precursor of this invention, it is preferable from the point of storage stability that the terminal of a polymer is end-capped with the structure which does not contain an acid anhydride group or active hydrogen.
As a method of end-capping with a structure not containing an acid anhydride group or active hydrogen, for example, in the case of an amine-terminated polyimide precursor, a method of amidation with acetic anhydride, phthalic anhydride or a few -The method of making an terminal an amic acid with acid anhydrides, such as a naphthalic anhydride, etc. are mentioned.
If the terminal is an aromatic carboxylic acid, even if it has active hydrogen, it reacts with vinyl ether at room temperature to form a hemiacetal ester, and in this case, storage stability is not lowered.

  The method for producing a polyimide precursor according to the present invention may use only a vinyl ether compound and, if necessary, a solvent in addition to an acid dianhydride and a diamine, which are raw materials for the polyimide precursor, and more appropriately, a surface activity. You may mix | blend other components, such as an agent.

Next, the polyimide manufacturing method according to the present invention comprises dehydrating and condensing the polyimide precursor manufactured by the polyimide precursor manufacturing method according to the present invention.
As a method of dehydrating the polyimide precursor and imidizing, a known method can be appropriately used. For example, there is a method of imidization by heating, a method of imidization using a dehydration catalyst such as acetic anhydride or dicyclohexylcarbodiimide, etc., but when making a polyimide film or molded body, it is usually heated It is preferable to perform imidization.

For example, when a polyimide film is produced using a polyimide precursor produced by the production method of the present invention, first, a resin composition containing a polyimide precursor produced by the production method of the present invention is placed on a substrate. And dried to obtain a polyimide precursor film. At this time, the substrate is an object on which a polyimide film is to be formed, and examples thereof include metals such as copper and stainless steel, inorganic materials such as silicon, metal oxides, and metal nitrides, and organic materials such as polyimide and polybenzoxazole. However, in the present invention, although the adhesiveness and the like slightly change depending on the substrate, the substrate is not particularly limited because the pattern formation and the characteristics of the obtained film are essentially not changed.
Examples of the application method include spin coating, die coating, and dip coating, but are not particularly limited, and known methods can be used. The pattern forming method of the present invention can be used for a film obtained by any coating method.
For drying, a known heating method such as a hot plate or an oven can be appropriately used.

In imidization by heating, imidization is often performed by heating with an oven or a hot plate.
In general, it is said that polyamic acid gradually undergoes imidization from about 150 ° C., and imidization is almost completed at a temperature of 200 ° C. or higher. However, when higher reliability is required, it is necessary to proceed with imidization more completely. In that case, it is ideal to heat the polyimide film finally obtained at a temperature equal to or higher than Tg. is there. However, in general, a polyimide film having sufficiently practical reliability can be obtained by heating at a temperature of 300 ° C. to 400 ° C.

  In the case of the polyimide precursor produced by the production method of the present invention, since the hemiacetal ester bond is almost completely decomposed at about 150 ° C., it is possible to increase the heating time at a temperature of 150 ° C. More complete detachment of the derived component can be promoted. The longer the heating time, the better from the viewpoint of reducing the residue in the polyimide. However, in order to balance the productivity, the heating is performed at a temperature in the range of 40 ° C. to 150 ° C. for 1 minute to 180 minutes in total. The heating is preferably performed for 5 minutes to 120 minutes.

Thereafter, in order to completely proceed with imidization, heating is performed in the range of 180 ° C. to 450 ° C., preferably 200 ° C. to 400 ° C. depending on the purpose. Preferably, the maximum heating temperature is 251 ° C. or higher and 400 ° C. or lower.
In particular, when a temperature of 100 ° C. or higher is applied, it is preferably performed in an inert atmosphere such as nitrogen or argon in order to prevent oxidation of the polyimide or the substrate. Furthermore, in order to reduce the residue in a polyimide, it is preferable to carry out under reduced pressure.

  In the method for producing polyimide according to the present invention, other than the polyimide precursor produced by the production method according to the present invention, in order to impart processing characteristics and various functionalities, as long as the object and effects of the present invention are not hindered. In addition, various organic or inorganic low-molecular or high-molecular compounds may be blended. For example, dyes, surfactants, leveling agents, plasticizers, fine particles and the like can be used. The fine particles include organic fine particles such as polystyrene and polytetrafluoroethylene, inorganic fine particles such as colloidal silica, carbon, and layered silicate, and these may have a porous or hollow structure. The function or form includes pigments, fillers, fibers, and the like.

  The mixing ratio of other optional components is appropriately selected depending on the properties of the optional components and is not particularly limited, but is preferably in the range of 0.1% by weight to 30% by weight with respect to the entire solid content. If it is less than 0.1% by weight, the effect of adding the additive is difficult to be exhibited, and if it exceeds 30% by weight, the properties of the finally obtained cured resin are hardly reflected in the final product.

Since the polyimide obtained from the polyimide precursor produced by the production method of the present invention is excellent in the detachability of the hemiacetal esterification site of the precursor, the content of the decomposition residue derived from the protective component is small. Therefore, the original properties such as heat resistance, dimensional stability, and insulation of polyimide are not impaired and are good.
For example, the 5% weight loss temperature measured in nitrogen of polyimide produced by the production method of the present invention is preferably 250 ° C. or higher, and more preferably 300 ° C. or higher. In particular, when used in applications such as electronic parts that pass through the solder reflow process, if the 5% weight loss temperature is 300 ° C. or less, defects such as bubbles occur due to the decomposition gas generated in the solder reflow process. There is a fear.
Here, the 5% weight reduction temperature is the time when the weight of the sample is reduced by 5% from the initial weight when the weight loss is measured using a thermogravimetric analyzer (in other words, the sample weight becomes 95% of the initial weight). Temperature). Similarly, the 10% weight reduction temperature is a temperature at which the sample weight is reduced by 10% from the initial weight.

The glass transition temperature of the polyimide produced by the production method of the present invention is preferably 260 ° C. or higher from the viewpoint of heat resistance. This is important for electronic members that have a solder reflow process. In applications where a thermoforming process is considered, such as an optical waveguide, it is preferable to exhibit a glass transition temperature of about 120 ° C. to 400 ° C., and more preferably a glass transition temperature of about 200 ° C. to 370 ° C.
Here, when the polyimide produced by the production method of the present invention can be formed into a film shape, the glass transition temperature in the present invention is determined by tan δ (tan δ = loss elastic modulus (E ″) by dynamic viscoelasticity measurement. ) / Storage elastic modulus (E ′)). The dynamic viscoelasticity measurement can be performed, for example, with a viscoelasticity measuring apparatus Solid Analyzer RSA II (manufactured by Rheometric Scientific) at a frequency of 1 Hz and a temperature increase rate of 5 ° C./min. When polyimide cannot be formed into a film shape, the temperature is determined based on the inflection point of the baseline of the differential thermal analyzer (DSC).

From the viewpoint of dimensional stability, the linear thermal expansion coefficient of the polyimide produced by the production method of the present invention is preferably 60 ppm or less, and more preferably in the range of 0 ppm to 40 ppm. In the case of forming a film on a silicon wafer in a manufacturing process of a semiconductor element or the like, the range of 0 ppm to 25 ppm is more preferable from the viewpoint of adhesion and warpage of the substrate. Here, the linear thermal expansion coefficient in this invention can be calculated | required with the thermomechanical analyzer (TMA) of the film of the polyimide manufactured by the manufacturing method of this invention. Using a thermomechanical analyzer (for example, Thermo Plus TMA8310 (manufactured by Rigaku Corporation), the heating rate is 10 ° C./min, and the tensile load is 1 g / 25,000 μm ² so that the weight per cross-sectional area of the evaluation sample is the same. .

Similarly, from the viewpoint of dimensional stability, the polyimide obtained from the polyimide precursor produced by the production method of the present invention preferably has a humidity expansion coefficient of 40 ppm or less, more preferably 20 ppm or less. Ideally, 10 ppm to 0 ppm is preferable.
Here, the humidity expansion coefficient in this invention can be calculated | required with the humidity variable mechanical analyzer (S-TMA) of the polyimide film manufactured by the manufacturing method of this invention. With a variable humidity mechanical analyzer (for example, Thermo Plus TMA8310 modified (manufactured by Rigaku Corporation)), the temperature is kept constant at 25 ° C., and the humidity is 50% with the sample stabilized in an environment of 20% RH. The change in sample length when it is changed to Rh and becomes stable is divided by the change in humidity (in this case, 30 of 50-20), and the value divided by the sample length is the humidity expansion coefficient. . The tensile load is 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample is the same.

As described above, the method for producing a polyimide precursor of the present invention has relatively high solubility by polymerizing one or more acid dianhydrides and one or more diamines in the presence of a vinyl ether compound. It is possible to obtain a polyimide precursor in one pot without using an amide solvent by performing hemiacetal esterification in parallel with polymerization at a high low molecular weight stage and proceeding with polymerization while improving solubility Become. If the manufacturing method of the polyimide precursor of this invention is used, even if it is a polyimide precursor which has a structure which shows high heat resistance and low linear thermal expansion, it can manufacture with a sufficient yield. The method for producing a polyimide precursor of the present invention can provide a polyimide precursor having high storage stability by having a hemiacetal ester bond that can be easily synthesized with an inexpensive raw material. In addition, the method for producing a polyimide precursor of the present invention can obtain a polyimide precursor capable of obtaining a polyimide with very little residual impurities after imidization more easily and at low cost. The polyimide precursor having a hemiacetal ester bond is a polyimide that is finally obtained because the hemiacetal ester bond is easily decomposed and the decomposition product other than polyamic acid generated by the decomposition of the hemiacetal ester bond is highly volatile. This is because there is almost no residue in the film.
Furthermore, the present invention is not limited to the skeleton of the polyimide precursor to be used and can be applied.

  The polyimide precursor produced by the production method of the present invention is a resin material such as printing ink, adhesive, filler, electronic material, optical circuit component, molding material, resist material, building material, three-dimensional modeling, optical member, etc. It can be used for all known fields and products used.

Since the polyimide precursor manufactured by the manufacturing method of the present invention can select a polyimide precursor having a wide range of structures, the cured product obtained is characterized by a polyimide having heat resistance, dimensional stability, insulation, etc. Since the function which it has is possible, it is suitable as a film for all the well-known members to which the polyimide is applied, a coating film, or a three-dimensional structure.
The polyimide precursor produced by the production method of the present invention can be used in a wide range of fields and products in which properties such as heat resistance, dimensional stability, and insulation are effective, such as paints or printing inks, color filters, flexible It is suitably used as a display film, semiconductor device, electronic component, interlayer insulating film, wiring coating film, optical circuit, optical circuit component, antireflection film, hologram, optical member, or building material.

Example 1
A 200 ml three-necked flask was heated in a nitrogen stream and sufficiently dried, then returned to room temperature (25 ° C.), while paying careful attention to moisture in the air, 3, 3 ′, 4, 4′-3. , 3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA) 5.88 g (20 mmol), cyclohexyl vinyl ether (CVE) 30 g, and 25 g of pre-dehydrated γ-butyrolactone were added at room temperature under a nitrogen stream. Stir.
A solution prepared by dissolving 4.0 g (20 mmol) of 4,4′-diaminodiphenyl ether (ODA) in 20 g of previously dehydrated γ-butyrolactone was gradually added dropwise over 30 minutes. After completion of the dropwise addition, a precipitate was deposited, but when the stirring was continued at room temperature, the precipitate was completely dissolved. The reaction was terminated by stirring for 168 hours.
A part of the solution was purified by reprecipitation with dehydrated diethyl ether to give a white solid. The white solid deuterated dimethyl sulfoxide solution was analyzed by ¹ H-NMR. As a result, BPDA-ODA (3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride with all carboxyl groups protected by CVE and 4,4′-diaminodiphenyl ether). Analyzed by ¹ H-NMR, the protection ratio (carboxyl) was determined based on the integral value of the peak of hydrogen bonded to carbon between oxygen and oxygen in the hemiacetal ester bond around 6.2 ppm and the integral ratio of the hydrogen peak of the aromatic ring of diphenyl ether. It was confirmed that the reaction rate of the hemiacetal ester bond to the group was 100%. ^The number average molecular weight determined by the ratio of the integral ratio of the peak derived from the end group of the ¹ H-NMR spectrum and the integral value of the peak of the diphenyl ether moiety of the repeating unit was 9,200. (Polyimide precursor 1)

(Examples 2-3)
Synthesis was performed under the same conditions as in Example 1, except that cyclohexyl vinyl ether was changed to other vinyl ether compounds shown in Table 1. In all experiments, gelation did not occur and white solids of polyimide precursors 2 to 3 were obtained. The reaction time of the polyimide precursor 2 and the polyimide precursor 3 was 220 hours and 150 hours, respectively.

  At the same time, the reaction liquids half left in Examples 1 to 3 were designated as Reaction liquids 1 to 3, and there were no changes such as gelation and precipitate formation until 200 hours after storage at room temperature.

(Comparative Example 1)
A 100 ml three-necked flask was heated in a nitrogen stream and dried thoroughly, then polymerized with a dimethylacetamide solvent, paying careful attention to moisture in the air, reprecipitated with acetone, and then dried BPDA -ODA (number average molecular weight Mn = 12000 determined by polyamic acid NMR consisting of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride and 4,4′-diaminodiphenyl ether), white solid, 0.99 g, cyclohexyl 5 g of vinyl ether (CVE) and 5 ml of dried γ-butyrolactone were added. The mixture was stirred with a magnetic stirrer for 88 hours at room temperature under a dry nitrogen stream. Initially, BPDA-ODA did not dissolve, but dissolved with the progress of the reaction, resulting in a brown solution. Thereafter, half of the reaction solution was reprecipitated with dried diethyl ether to quantitatively obtain a white solid of BPDA-ODA cyclohexyl vinyl ether protector (polyimide precursor 1) represented by the following formula. Analyzed by ¹ H-NMR, the protection ratio (carboxyl) was determined from the integral value of the hydrogen peak bound to carbon between oxygen and oxygen of the hemiacetal ester bond around 6.2 ppm and the integral ratio of the hydrogen peak of the aromatic ring of diphenyl ether. It was confirmed that the reaction rate of the hemiacetal ester bond to the group was 100%. (Comparative polyimide precursor 1)

<Thermal decomposition evaluation>
Using a 2% by weight heavy dimethyl sulfoxide solution (non-dehydrated) of polyimide precursor 1 and comparative polyimide precursor 1, the protection rate when heated was measured. The degree of protection was determined from the integral ratio of the peak using 1H-NMR in the same manner as in Synthesis Example 1 after heating in an NMR tube at each temperature for 5 minutes.
As a result, it was confirmed that in all samples, the protecting group was almost completely decomposed at 80 ° C. and changed to polyamic acid.
From these results, it is possible to obtain a polyimide precursor that does not change in characteristics even if the production method of the present invention is used or if a method of performing hemiacetal esterification using a vinyl ether compound after synthesizing a polyamic acid is used. I understood.

<Infrared spectroscopic evaluation>
Each of BPDA-ODA used for the production of polyimide precursor 1 and Comparative Example 1 was heat-treated at 350 ° C. for 1 hour (temperature increase rate from room temperature: 10 ° C./min) in a nitrogen atmosphere. When the spectrum was measured, although the baseline was slightly shifted, all the main peaks had the same wave number and showed almost the same spectrum.

<Glass transition temperature after imidization>
The reaction solution 1 is applied to a Upilex S 50S (trade name: Ube Industries) film affixed on glass, dried on a hot plate at 80 ° C. for 10 minutes, dried, peeled off, and film A film with a thickness of 15 μm was obtained.
Similarly, a 15% by weight NMP solution of BPDA-ODA was applied to a Upilex S 50S (trade name: Ube Industries) film pasted on glass, dried on a hot plate at 80 ° C. for 10 minutes, and then peeled off. A film having a thickness of 12 μm was obtained.
The above two samples were heated at 350 ° C. for 1 hour in a nitrogen atmosphere (temperature increase rate: 10 ° C./min), polyimide precursor 1, BPDA-ODA (respectively thickness 8 μm ± 1 μm), A film was obtained.

The above-mentioned film was subjected to dynamic viscoelasticity measurement at a frequency of 1 Hz and a heating rate of 5 ° C./min using a viscoelasticity measuring apparatus Solid Analyzer RSA II (manufactured by Rheometric Scientific).
As a result, the glass transition temperature after imidation of the polyimide precursor 1 was 257 ° C., and the film after imidization of BPDA-ODA was 258 ° C.

<Linear thermal expansion coefficient after imidization>
Two types of films prepared for measuring the glass transition temperature were cut into a width of 5 mm and a length of 20 mm and used as evaluation samples. The linear thermal expansion coefficient was measured by a thermomechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation). The measurement conditions were such that the observation length of the evaluation sample was 15 mm, the heating rate was 10 ° C./min, and the tensile load was 1 g / 25,000 μm ² so that the weight per cross-sectional area of the evaluation sample was the same.
As a result, the linear thermal expansion coefficient after imidization of the polyimide precursor 1 was 44.2 ppm, and the film after imidization of BPDA-ODA was 43.9 ppm.

<Humidity expansion coefficient after imidization>
Two types of films prepared for measuring the glass transition temperature were cut into a width of 5 mm and a length of 20 mm and used as evaluation samples. The humidity expansion coefficient was measured by a humidity variable mechanical analyzer Thermo Plus TMA8310 (manufactured by Rigaku Corporation). When the temperature is constant at 25 ° C. and the humidity is stable in an environment of 20% RH, the humidity is changed to 50% RH. And the value obtained by dividing the value by the sample length was defined as the humidity expansion coefficient. The tensile load was 1 g / 25000 μm ² so that the weight per cross-sectional area of the evaluation sample was the same.
As a result, the humidity expansion coefficient after imidation of the polyimide precursor 1 was 21.9 ppm, and the film of BPDA-ODA was 21.8 ppm.

Claims (18)

  A method for producing a polyimide precursor, which comprises polymerizing one or more acid dianhydrides and one or more diamines in a solution containing a vinyl ether compound.   2. The polyimide precursor according to claim 1, wherein a state in which the acid dianhydride is dispersed or dissolved in a solution containing the vinyl ether compound is formed, and then the diamine is added and polymerized. 3. Manufacturing method.   2. The method of forming a state in which the acid dianhydride is dispersed or dissolved in a solution containing the vinyl ether compound, and then adding and polymerizing the solution in which the diamine is dissolved. 2. A method for producing a polyimide precursor according to 2.   The method for producing a polyimide precursor according to any one of claims 1 to 3, wherein the solution containing the vinyl ether compound contains one or more solvents selected from lactones and esters.   The method for producing a polyimide precursor according to any one of claims 1 to 4, wherein the solution containing the vinyl ether compound does not contain an active hydrogen other than the acid dianhydride and the diamine.   The method for producing a polyimide precursor according to any one of claims 1 to 5, wherein the reaction is performed at 0 ° C to 45 ° C in a solution containing the vinyl ether compound.   The method for producing a polyimide precursor according to any one of claims 1 to 6, wherein the solution containing the vinyl ether compound has a water content of 1% by weight or less. The method for producing a polyimide precursor according to claim 1, wherein a polyimide precursor having a repeating unit represented by the following formula (1) is produced.
(In Formula (1), R ¹ is a tetravalent organic group, R ² is a divalent organic group, and R ¹ and R ² that are repeated may be the same or different. R ³ and R ⁴ are each independently a monovalent organic group having the structure of the following formula (2), and they may be the same or different, and repeated R ³ and R ⁴ are Each may be the same or different.)
(In the formula (2), R ⁵ , R ⁶ and R ⁷ are each independently hydrogen, a halogen atom, a substituted or unsubstituted alkyl group, an allyl group or an aryl group, and R ⁸ is a group having a hydrocarbon skeleton. R ⁵ , R ⁶ , R ⁷ and R ⁸ may be bonded to each other to show a cyclic structure.   The method for producing a polyimide precursor according to any one of claims 1 to 8, wherein the polyimide precursor to be produced has a weight average molecular weight or a number average molecular weight of 2,000 to 1,000,000. The manufacturing method of the polyimide precursor of Claim 8 or 9 whose R < ⁵ >, R < ⁶ >, R < ⁷ > in said Formula (2) is hydrogen. The method for producing a polyimide precursor according to any one of claims 8 to 10, wherein R ⁸ in the formula (2) is an organic group having 2 to 30 carbon atoms and does not contain active hydrogen. . The method for producing a polyimide precursor according to claim 8, wherein R ⁸ in the formula (2) contains an ether bond.   The method for producing a polyimide precursor according to any one of claims 1 to 12, wherein a terminal of the polymer has a structure containing no acid anhydride group or active hydrogen. The method for producing a polyimide precursor according to any one of claims 8 to 13, wherein R ¹ in the formula (1) is a skeleton derived from an aromatic tetracarboxylic dianhydride. The manufacturing method of the polyimide precursor in any one of Claims 8 thru | or 14 whose 33 mol% or more among R < ¹ > in said Formula (1) is either structure represented by following formula (3).
Formula (1) 33 mol% or more of R ² in is any of structures represented by the following formula (4), the production method of the polyimide precursor according to any one of claims 8 to 15.
(R ¹⁰ is a divalent organic group, an oxygen atom, a sulfur atom, or a sulfone group, and R ¹¹ and R ¹² are a monovalent organic group or a halogen atom.) Formula (1) 33 mol% or more of R ² in is any of structures represented by the following formula (5), the production method of the polyimide precursor according to any one of claims 8 to 16.
(A is a natural number of 1 or more, and an amino group is bonded to a meta position or a para position with respect to a bond between benzene rings. R ¹¹ and R ¹² are a monovalent organic group or a halogen atom.)   The manufacturing method of a polyimide which consists of dehydrating and condensing the polyimide precursor manufactured by the manufacturing method of the polyimide precursor in any one of the said Claims 1 thru | or 17.