JP2012140517A - Novel polyamic acid, novel polyimide and novel diamine compound - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel polyamic acid low in viscosity in preparation of a solution and excellent in handleability, a novel polyimide generating few cracks in film formation and high in heat resistance, and a novel diamine compound useful as a raw material monomer in production of the polyamic acid and the polyimide.SOLUTION: The raw material monomer used in production of the polyamic acid and the polyimide is a diamine compound represented by formula (I) (wherein X, Y and Z denote a 1-10C alkyl group which may be substituted with a halogen atom or the like; k denotes the number of 0 to 4; p denotes the number of 0 to 8; r denotes the number of 0 to 4; x denotes the number of 0 to 4; y denotes the number of 0 to 4; and the total of the numbers of x and y is 2 to 4).

Description

  The present invention relates to a novel polyamic acid excellent in handling properties, a novel polyimide excellent in heat resistance and film-forming property, and a novel diamine compound used as a raw material for the polyamic acid and the polyimide.

  Conventionally, polyimide-based materials have excellent heat resistance, transparency, physical strength, insulation, solvent resistance, and electrical insulation, so adhesives, protective materials, sheet materials, sealing materials, electronic circuits It is used for electronic materials such as insulating materials, interlayer insulating materials (interlayer insulating films) of layer wiring boards, surface protective films of semiconductor elements, and color filters.

  Many studies have been conducted on 9,9-bis (4-aminophenyl) fluorene and derivatives having substituents introduced into the skeleton thereof as diamine compounds that satisfy the above conditions and have good heat resistance. For example, Patent Documents 1 to 3 are disclosed.

  Usually, since polyimide is dissolved in a solvent and applied directly to a base material to form a protective film, it is required to have a low viscosity when the solvent is dissolved. However, the polyimide obtained from the diamine compound having a fluorene skeleton as described in Patent Documents 1 to 3 has a problem that the resin composition has a high viscosity when the polyamic acid solution is prepared and the handling property is poor. Further, the polyimide having a fluorene skeleton has a problem that cracks are likely to occur depending on the production method.

JP-A-5-31341 JP-T-2004-500463 JP 2008-81418 A

  An object of the present invention is to provide a novel polyamic acid having a low viscosity at the time of solution preparation and excellent handling properties, a novel polyimide having less cracking during film formation and high heat resistance, and a raw material for producing the polyamic acid and the polyimide The object is to provide a novel diamine compound useful as a monomer.

  As a result of intensive studies, the present inventors have found that a polyamic acid and a polyimide obtained by polycondensation of a specific diamine compound and a specific tetracarboxylic acid can achieve the above object.

（式中、Ｘ、Ｙ及びＺは、それぞれ独立して、ハロゲン原子で置換されていてもよい炭素原子数１〜１０のアルキル基、ハロゲン原子で置換されていてもよい炭素原子数６〜２０のアリール基、ハロゲン原子で置換されていてもよい炭素原子数６〜２０のアリールオキシ基、ハロゲン原子で置換されていてもよい炭素原子数６〜２０のアリールチオ基、ハロゲン原子で置換されていてもよい炭素原子数８〜２０のアリールアルケニル基、ハロゲン原子で置換されていてもよい炭素原子数７〜２０のアリールアルキル基、ハロゲン原子で置換されていてもよい炭素原子数２〜２０の複素環基又はハロゲン原子を表し、
該アルキル基及びアリールアルキル基中のメチレン基並びに該アリール基中の直接結合は、不飽和結合、−Ｏ−又は−Ｓ−で中断されていてもよく、Ｘは、隣接するＸ同士で環を形成していてもよく、
ｋは０〜４の数を表し、ｐは０〜８の数を表し、ｒは０〜４の数を表し、ｘは０〜４の数を表し、ｙは０〜４の数を表し、ｘとｙの数の合計は２〜４であり、光学異性体が存在する場合、どの異性体でもよい。） That is, the present invention has been made on the basis of the above knowledge, and is obtained by polycondensing a diamine compound represented by the following general formula (I) and a tetracarboxylic acid or tetracarboxylic dianhydride having 6 to 24 carbon atoms. A novel polyamic acid is provided.

(In the formula, X, Y and Z are each independently an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, or 6 to 20 carbon atoms which may be substituted with a halogen atom. An aryloxy group having 6 to 20 carbon atoms which may be substituted with a halogen atom, an arylthio group having 6 to 20 carbon atoms which may be substituted with a halogen atom, or a halogen atom An arylalkenyl group having 8 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms which may be substituted with a halogen atom, or a complex having 2 to 20 carbon atoms which may be substituted with a halogen atom Represents a cyclic group or a halogen atom,
The methylene group in the alkyl group and arylalkyl group and the direct bond in the aryl group may be interrupted by an unsaturated bond, -O- or -S-, and X is a ring between adjacent Xs. May be formed,
k represents a number from 0 to 4, p represents a number from 0 to 8, r represents a number from 0 to 4, x represents a number from 0 to 4, y represents a number from 0 to 4, The total number of x and y is 2 to 4, and any optical isomer may be used if it exists. )

（式中、Ｘ、Ｙ、Ｚ、ｋ、ｐ、ｒ、ｘ、及びｙは上記一般式（I）と同じであり、Ａは炭素原子数２〜２０のテトラカルボン酸残基である。） The present invention also provides a novel polyimide having a unit represented by the following general formula (IV).

(In the formula, X, Y, Z, k, p, r, x, and y are the same as those in the general formula (I), and A is a tetracarboxylic acid residue having 2 to 20 carbon atoms.)

  Moreover, this invention provides the film or sheet | seat formed using the said polyimide.

（式中、Ｘ、Ｙ及びＺは、それぞれ独立して、ハロゲン原子で置換されていてもよい炭素原子数１〜１０のアルキル基、ハロゲン原子で置換されていてもよい炭素原子数６〜２０のアリール基、ハロゲン原子で置換されていてもよい炭素原子数６〜２０のアリールオキシ基、ハロゲン原子で置換されていてもよい炭素原子数６〜２０のアリールチオ基、ハロゲン原子で置換されていてもよい炭素原子数８〜２０のアリールアルケニル基、ハロゲン原子で置換されていてもよい炭素原子数７〜２０のアリールアルキル基、ハロゲン原子で置換されていてもよい炭素原子数２〜２０の複素環基又はハロゲン原子を表し、
該アルキル基及びアリールアルキル基中のメチレン基並びに該アリール基中の直接結合は、不飽和結合、−Ｏ−又は−Ｓ−で中断されていてもよく、Ｘは、隣接するＸ同士で環を形成していてもよく、
ｋは０〜４の数を表し、ｐは０〜８の数を表し、ｒは１〜４の数を表し、ｘは０〜４の数を表し、ｙは０〜４の数を表し、ｘとｙの数の合計は２〜４であり、光学異性体が存在する場合、どの異性体でもよい。） The present invention also provides a novel diamine compound represented by the following general formula (I ′).

(In the formula, X, Y and Z are each independently an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, or 6 to 20 carbon atoms which may be substituted with a halogen atom. An aryloxy group having 6 to 20 carbon atoms which may be substituted with a halogen atom, an arylthio group having 6 to 20 carbon atoms which may be substituted with a halogen atom, or a halogen atom An arylalkenyl group having 8 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms which may be substituted with a halogen atom, or a complex having 2 to 20 carbon atoms which may be substituted with a halogen atom Represents a cyclic group or a halogen atom,
The methylene group in the alkyl group and arylalkyl group and the direct bond in the aryl group may be interrupted by an unsaturated bond, -O- or -S-, and X is a ring between adjacent Xs. May be formed,
k represents a number from 0 to 4, p represents a number from 0 to 8, r represents a number from 1 to 4, x represents a number from 0 to 4, y represents a number from 0 to 4, The total number of x and y is 2 to 4, and any optical isomer may be used if it exists. )

  The novel diamine compound of the present invention provides a novel polyamic acid having a low viscosity and excellent handling properties, and a novel polyimide having high heat resistance and excellent film forming properties.

Hereinafter, the novel polyamic acid of the present invention, the novel polyimide, and the novel diamine compound suitable as a raw material monomer for the polyamic acid and the polyimide will be described in detail based on preferred embodiments.
First, the diamine compound represented by the above general formula (I), which is a raw material for producing the novel polyamic acid and novel polyimide of the present invention, will be described.

  Examples of the alkyl group having 1 to 10 carbon atoms which may be substituted with the halogen atom represented by X, Y and Z in the general formula (I) include, for example, methyl, ethyl, propyl, isopropyl, butyl, s -Butyl, t-butyl, isobutyl, amyl, isoamyl, t-amyl, hexyl, heptyl, isoheptyl, t-heptyl, n-octyl, isooctyl, t-octyl, 2-ethylhexyl, n-nonyl, n-decyl, tri Fluoromethyl, difluoromethyl, monofluoromethyl, pentafluoroethyl, tetrafluoroethyl, trifluoroethyl, difluoroethyl, heptafluoropropyl, hexafluoropropyl, pentafluoropropyl, tetrafluoropropyl, trifluoropropyl, perfluorobutyl, trichloro Tyl, dichloromethyl, monochloromethyl, trichloroethyl, dichloroethyl, tetrachloropropyl, trichloropropyl, tribromomethyl, dibromomethyl, monobromomethyl, tribromoethyl, dibromoethyl, tribromopropyl, diiodomethyl, monoiodomethyl, methoxy , Methoxymethyl, methoxyethyl, methoxyethoxy, methoxyethoxyethoxy, methylthio, ethoxy, ethoxymethyl, ethoxyethyl, ethylthio, vinyloxy, propoxy, isopropoxy, butoxy, butylthio, isobutoxy, t-butoxy, pentyloxy, pentylthio, isopentyl Oxy, t-pentyloxy, neopentyloxy, hexyloxy, hexylthio, cyclohexyloxy, isohexyloxy, Yloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, straight chains such as cyclodecyl, for example, an alkyl group of branched and cyclic.

  Examples of the aryl group having 6 to 20 carbon atoms which may be substituted with the halogen atom represented by X, Y and Z in the general formula (I) include phenyl, 1-naphthyl, 2-naphthyl, 1 -Anthryl, 1-phenanthryl, o-tolyl, m-tolyl, p-tolyl, 3-fluorenyl, 9-fluorenyl, 1-tetrahydronaphthyl, 2-tetrahydronaphthyl, 1-acenaphthenyl, 1-indanyl, 2-indanyl, 4 -Vinylphenyl, 3-isopropylphenyl, 4-isopropylphenyl, 4-butylphenyl, 4-isobutylphenyl, 4-t-butylphenyl, 4-hexylphenyl, 4-cyclohexylphenyl, 4-octylphenyl, 4- (2 -Ethylhexyl) phenyl, 2,3-dimethylphenyl, 2,4-dimethyl Phenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, 2,4-di-t-butylphenyl, 2,5-di-t-butyl Phenyl, 2,6-di-t-butylphenyl, 2,4-di-t-pentylphenyl, 2,5-di-t-amylphenyl, cyclohexylphenyl, biphenyl, 2,4,5-trimethylphenyl, 4 -Chlorophenyl, 3,4-dichlorophenyl, 4-trichlorophenyl, 4-trifluorophenyl, perfluorophenyl and the like.

  Examples of the aryloxy group having 6 to 20 carbon atoms which may be substituted with the halogen atom represented by X, Y and Z in the general formula (I) include, for example, phenoxy, 2-methylphenoxy, 3-methyl Phenoxy, 4-methylphenoxy, 2,3-dimethylphenoxy, 2,4-dimethylphenoxy, 2,5-dimethylphenoxy, 2,6-dimethylphenoxy, 3,4-dimethylphenoxy, 3,5-dimethylphenoxy, 2 , 3,4-trimethylphenoxy, 2,3,5-trimethylphenoxy, 2,3,6-trimethylphenoxy, 2,4,5-trimethylphenoxy, 2,4,6-trimethylphenoxy, 3,4,5- Trimethylphenoxy, 2,3,4,5-tetramethylphenoxy, 2,3,4,6-tetramethylphenoxy, 2 3,5,6-tetramethylphenoxy, pentamethylphenoxy, ethylphenoxy, n-propylphenoxy, isopropylphenoxy, n-butylphenoxy, sec-butylphenoxy, tert-butylphenoxy, n-hexylphenoxy, n-octylphenoxy, n-decylphenoxy, n-tetradecylphenoxy, 1-naphthoxy, 2-naphthoxy, 1-anthryloxy, 1-phenanthryloxy, o-tolyloxy, m-tolyloxy, p-tolyloxy, 9-fluorenyloxy 1-tetrahydronaphthoxy, 2-tetrahydronaphthoxy, 1-acenaphthenyloxy, 1-indanyloxy, 2-indanyloxy and the like.

  Examples of the arylthio group having 6 to 20 carbon atoms which may be substituted with the halogen atom represented by X, Y and Z in the general formula (I) include, for example, phenylthio, 2-methylphenylthio, 3-methyl Phenylthio, 4-methylphenylthio, 2,3-dimethylphenylthio, 2,4-dimethylphenylthio, 2,5-dimethylphenylthio, 2,6-dimethylphenylthio, 3,4-dimethylphenylthio, 3 , 5-dimethylphenylthio, 2,3,4-trimethylphenylthio, 2,3,5-trimethylphenylthio, 2,3,6-trimethylphenylthio, 2,4,5-trimethylphenylthio, 2,4 , 6-trimethylphenylthio, 3,4,5-trimethylphenylthio, 2,3,4,5-tetramethylphenylthio, 2,3,4 6-tetramethylphenylthio, 2,3,5,6-tetramethylphenylthio, pentamethylphenylthio, ethylphenylthio, n-propylphenylthio, isopropylphenylthio, n-butylphenylthio, sec-butylphenylthio Tert-butylphenylthio, n-hexylphenylthio, n-octylphenylthio, n-decylphenylthio, n-tetradecylphenylthio, 1-naphthylthio, 2-naphthylthio, 1-anthrylthio, 1-phenanthrylthio, Examples include o-tolylthio, m-tolylthio, p-tolylthio, 9-fluorenylthio, 1-tetrahydronaphthylthio, 2-tetrahydronaphthylthio, 1-acenaphthenylthio, 1-indanylthio, 2-indanylthio and the like.

  Examples of the arylalkenyl group having 8 to 20 carbon atoms which may be substituted with the halogen atom represented by X, Y and Z in the general formula (I) include styryl, 4-fluorostyryl and the like. .

  Examples of the arylalkyl group having 7 to 20 carbon atoms which may be substituted with the halogen atom represented by X, Y and Z in the general formula (I) include benzyl, phenethyl, 2-phenylpropyl and diphenyl. Examples include methyl, triphenylmethyl, 4-chlorophenylmethyl, benzyloxy, 1-naphthylmethoxy, 2-naphthylmethoxy, 1-anthrylmethoxy and the like.

  Examples of the heterocyclic group having 2 to 20 carbon atoms which may be substituted with the halogen atom represented by X, Y and Z in the general formula (I) include pyrrolyl, pyridyl, pyrimidyl, pyridazyl, piperazyl, Piperidyl, pyranyl, pyrazolyl, triazyl, pyrrolidyl, quinolyl, isoquinolyl, imidazolyl, benzimidazolyl, triazolyl, furyl, furanyl, benzofuranyl, thienyl, thiophenyl, benzothiophenyl, thiadiazolyl, thiazolyl, benzothiazolyl, oxazolyl, benzoxazolyl, isothiazolyl, isoxazolyl , Indolyl, euroridyl, morpholinyl, thiomorpholinyl, 2-pyrrolidinon-1-yl, 2-piperidone-1-yl, 2,4-dioxyimidazolidin-3-yl, 2,4 Dioxy oxazolidine-3-yl, and the like.

  Examples of the ring structure formed by adjacent Xs in the general formula (I) include 5 to 5 such as cyclopentane ring, cyclohexane ring, cyclopentene ring, benzene ring, piperidine ring, morpholine ring, lactone ring, and lactam ring. Examples thereof include 7-membered rings and condensed rings such as naphthalene ring, anthracene ring, fluorene ring, acenaphthene ring, indane ring and tetralin ring.

A halogen atom represented by X, Y and Z in the general formula (I), and an alkyl group, aryl group, arylalkyl group, aryloxy group represented by X, Y and Z in the general formula (I); Examples of the halogen atom that may substitute the arylthio group, arylalkenyl group and heterocyclic group include fluorine, chlorine, bromine and iodine.
In addition, the substitution number and substitution position of the halogen atom which may substitute the group such as an alkyl group represented by X, Y and Z in the general formula (I) are arbitrary.

  In the general formula (I), the methylene group in the alkyl group and arylalkyl group and the direct bond in the aryl group may be interrupted by an unsaturated bond, -O- or -S-, and the unsaturated bond, -O The interruption position of-or -S- is arbitrary, and includes those in which -O- or -S- is directly bonded to each ring.

  In the diamine compound represented by the above general formula (I), optical isomers may exist, but any isomer may be used, and the compounds shown in the following text are limited to specific optical isomers. Not what you want.

  Among the diamine compounds represented by the general formula (I), examples of the compound of r = 0 include the following compound No. 1, no. 2, No. 5-No. 28, and examples of the compound with r = 1 include No. 28. 3, no. 4, no. 29-No. 47, but is not limited to these compounds.

Among these diamine compounds, a compound in which each group in the general formula (I) satisfies the following conditions is preferable because the raw materials are easily available, the productivity is good, and the storage stability is excellent.
a compound in which x is 2 or 3, preferably 2; a compound in which y is 0; a compound in which k is 0 to 2, preferably 0 or 1, more preferably 0, and when k is 1 or more, X is carbon A compound in which an alkyl group having 1 to 10 atoms, an aryl group having 6 to 20 carbon atoms, or a ring formed by X is an aromatic ring; a compound in which p is 0 to 2, preferably 1 or 2, p is 1 In the above case, Y is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms, preferably an alkyl group or phenyl group having 1 to 10 carbon atoms, more preferably a methyl group or a phenyl group. A compound; a compound in which r is 0 to 2, preferably 0 or 1, more preferably 1, and when r is 1 or more, Z is an alkyl group having 1 to 10 carbon atoms or an aryl having 6 to 20 carbon atoms Group, preferably 1 to 10 carbon atoms Alkyl group, compounds and more preferably a methyl group.

Furthermore, among the diamine compounds described above, a compound represented by the following general formula (II) is even more preferable. The preferred ranges of Z and r in the general formula (II) are the same as those in the general formula (I).
Moreover, as a combination of Y ¹ and Y ² in the following general formula (II), (1) Y ¹ and Y ² are hydrogen atoms; (2) Y ¹ is a hydrogen atom and Y ² is the number of carbon atoms. An alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms; (3) Y ¹ and Y ² are each independently an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms. The combination of Y ¹ and Y ² is preferably the above (2) or (3). When the combination of Y ¹ and Y ² is the above (2) or (3), Y ¹ and Y ² are preferably an alkyl group having 1 to 10 carbon atoms or a phenyl group, and are a methyl group or a phenyl group. It is more preferable. When the combination of Y ¹ and Y ² is (3) above, Y ¹ and Y ² may be the same or different substituents.

（式中、Ｚ及びｒは上記一般式（Ｉ）と同じであり、Ｙ¹及びＹ²はそれぞれ独立して水素原子、炭素原子数１〜１０のアルキル基又は炭素原子数６〜２０のアリール基である。）

(In the formula, Z and r are the same as those in the general formula (I), and Y ¹ and Y ² are each independently a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an aryl having 6 to 20 carbon atoms. Group.)

  The method for producing the diamine compound represented by the general formula (I) is not particularly limited. Org. Chem. Examples include a method of reacting 3,3-dimethyl-1-indanone produced in accordance with the method described in 1981, 46, 2974 and a commercially available aniline.

  The polyamic acid of the present invention is a compound obtained by a polycondensation reaction of the diamine compound represented by the above general formula (I) and a tetracarboxylic acid or tetracarboxylic dianhydride having 6 to 24 carbon atoms, It is a polyamic acid having a unit represented by the following general formula (III). In the present specification, tetracarboxylic acid and tetracarboxylic dianhydride are referred to as tetracarboxylic acids.

（式中、Ｘ、Ｙ、Ｚ、ｋ、ｐ、ｒ、ｘ及びｙは上記一般式（I）と同じであり、Ａは炭素原子数２〜２０のテトラカルボン酸残基である。）

(In the formula, X, Y, Z, k, p, r, x and y are the same as in the above general formula (I), and A is a tetracarboxylic acid residue having 2 to 20 carbon atoms.)

  Examples of the tetracarboxylic acid having 6 to 24 carbon atoms (carboxylic acid in a carboxylic acid residue having 2 to 20 carbon atoms represented by A in the general formula (III)) (hereinafter also referred to as tetracarboxylic acids) include: For example, pyromellitic acid, pyromellitic dianhydride, 2,2 ′, 3,3′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3 , 3 ′, 4,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 2, 3,5,6-pyridinetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 4,4 ′ Sulfonyl diphthalic dianhydride, m-terphenyl-3,3,4,4'-tetracarboxylic dianhydride, ethylene tetracarboxylic acid, 4,4'-oxydiphthalic dianhydride, bis (2,3 -Dicarboxyphenyl) methanoic dianhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis (2,3- or 3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3- or 3,4-dicarboxyphenyl) propane dianhydride, 2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane Anhydride, 1,1,1,3,3,3-hexafluoro-2,2-bis [4- (2,3- or 3,4-dicarboxyphenoxy) phenyl] propane dianhydride, 1,3 -Bis (3,4-dicarboxyphenyl) -1 1,3,3-tetramethyldisiloxane dianhydride, butanetetracarboxylic dianhydride, bicyclo- [2,2,2] -oct-7-ene-2,3,5,6-tetracarboxylic acid An anhydride etc. are mentioned.

As the tetracarboxylic acids, tetracarboxylic acids having a ring structure in the molecule are preferred because the raw materials are easily available, the solubility is high when polyamic acid is used, and the productivity is good. Are more preferable, and pyromellitic acid, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic acid or 3,3 ′, 4,4′-biphenyltetracarboxylic acid Anhydrides are more preferred, and pyromellitic acid or pyromellitic dianhydride is most preferred. That is, A in the general formula (III) is preferably the following formula (V) or (VI), more preferably the following formula (V).

（式中、Ｚ、ｒ、Ｙ¹及びＹ²は上記一般式（II）と同じであり、Ａは上記一般式（III）と同じである。） As the polyamic acid having a unit represented by the general formula (III), the raw materials are easily available, have high solubility, good productivity, and excellent storage stability. Therefore, X in the general formula (III) , Y, Z, k, p, r, x and y are preferably in the same range as the above general formula (I), and the polyamic acid having a unit represented by the following general formula (III-I) More preferred. In addition, the preferable combination of Y < ¹ > and Y < ² > in the following general formula (III-I) is the same as that of the said general formula (II).

(In the formula, Z, r, Y ¹ and Y ² are the same as the above general formula (II), and A is the same as the above general formula (III).)

The polyamic acid of the present invention can be produced by using a plurality of diamine compounds. For example, two or more of the diamine compounds represented by the general formula (I) can be used in combination. Moreover, irrespective of whether the diamine compound to be used is 1 type or 2 types or more, 1 type, or 2 or more types can be used also about the said tetracarboxylic acid.

  The average degree of polymerization of the polyamic acid of the present invention is not particularly limited, but is preferably a number of 2 to 5000. Further, the weight average molecular weight is not particularly limited as long as it is within the above-mentioned average degree of polymerization, but if it is too low, the heat resistance may be insufficient, and if it is too high, the solvent solubility may be deteriorated. 1000000 is preferable and 10000-500000 is more preferable.

  Although the usage-amount of the diamine compound and tetracarboxylic acid at the time of manufacturing the polyamic acid of this invention is not specifically limited, The usage-amount of this tetracarboxylic acid is 90-110 mol% with respect to this diamine compound. preferable. If the amount of tetracarboxylic acid used is less than 90 mol% or more than 110 mol%, the physical strength may be significantly reduced.

  The reaction temperature (polycondensation reaction temperature) at the time of producing the polyamic acid of the present invention varies depending on the type of diamine compound and tetracarboxylic acid to be used, but it is stirred in an organic solvent at 15 to 40 ° C. Is preferred.

  The organic solvent for producing the polyamic acid of the present invention is not particularly limited. For example, ketones such as methyl ethyl ketone, methyl amyl ketone, diethyl ketone, acetone, methyl isopropyl ketone, methyl isobutyl ketone, and cyclohexanone; ethyl ether, dioxane Ether solvents such as tetrahydrofuran, 1,2-dimethoxyethane, 1,2-diethoxyethane, dipropylene glycol dimethyl ether; methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, n-butyl acetate, etc. Ester solvent; Cellsolve solvent such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monomethyl ether acetate; methanol, ethanol, iso- or n-propyl Alcohol solvents such as panol, iso- or n-butanol and amyl alcohol; BTX solvents such as benzene, toluene and xylene; Aliphatic hydrocarbon solvents such as hexane, heptane, octane and cyclohexane; terpine oil, D-limonene Terpene hydrocarbon oil such as pinene; paraffinic solvents such as mineral spirit, swazol # 310 (Cosmo Matsuyama Oil Co., Ltd.), Solvesso # 100 (Exxon Chemical Co., Ltd.); carbon tetrachloride, chloroform, trichloroethylene, chloride Halogenated aliphatic hydrocarbon solvents such as methylene; Halogenated aromatic hydrocarbon solvents such as chlorobenzene; Carbitol solvents, aniline, triethylamine, pyridine, acetic acid, acetonitrile, carbon disulfide, N, N-dimethylformamide, N-methylpyrrolidone etc. Gerare, among others, .gamma.-butyrolactone or N- methylpyrrolidone is preferred.

Next, the polyimide of this invention is demonstrated. In addition, about the point which is not demonstrated especially, the description in the polyamic acid of this invention is applied suitably.
The polyimide of the present invention is obtained by (A) dehydrating condensation of the above-described polyamic acid of the present invention, or (B) the diamine compound represented by the above general formula (I) and the above tetracarboxylic acids. Preferably, the compound (A) is a compound produced by dehydration condensation of the polyamic acid of the present invention described above, and is a unit represented by the following general formula (IV). It is the polyimide which has.

（式中、Ｘ、Ｙ、Ｚ、ｋ、ｐ、ｒ、ｘ及びｙは上記一般式（I）と同じであり、Ａは上記一般式（III）と同じである。）

(In the formula, X, Y, Z, k, p, r, x and y are the same as in the above general formula (I), and A is the same as in the above general formula (III).)

（式中、Ｚ、ｒ、Ｙ¹及びＹ²は上記一般式（II）と同じであり、Ａは上記一般式（IV）と同じである。） The polyimide of the present invention is preferably a polyimide in which X, Y, Z, k, p, r, x and y in the general formula (IV) are in the same range as in the general formula (I). Polyimide having a unit represented by IV-I) is more preferable. A is preferably in the same range as the above general formula (III).

(In the formula, Z, r, Y ¹ and Y ² are the same as those in the general formula (II), and A is the same as the general formula (IV).)

The polyimide of this invention can be manufactured by using a several diamine compound similarly to the polyamic acid of this invention. For example, two or more of the diamine compounds represented by the general formula (I) can be used in combination. Moreover, irrespective of whether the diamine compound to be used is 1 type or 2 types or more, 1 type, or 2 or more types can be used also about the said tetracarboxylic acid.

  Although the usage-amount of the diamine compound and tetracarboxylic acid at the time of manufacturing the polyimide of this invention is not specifically limited, It is preferable that the usage-amount of this tetracarboxylic acid is 90-110 mol% with respect to this diamine compound. . If the amount of tetracarboxylic acid used is less than 90 mol% or more than 110 mol%, the physical strength may be significantly reduced.

  As a specific method for producing the polyimide of the present invention, for example, as the method (A), a tetracarboxylic dianhydride and a diamine compound are reacted in an organic solvent to form a polyamic acid, and then a dehydrating agent. Examples include a method of chemically dehydrating and cyclizing in an organic solvent in the presence to imidize, and as a method of the above (B), after reacting a tetracarboxylic dianhydride and a diamine compound in an organic solvent. A method of imidizing by dehydrating and ring-closing the reaction product by heating is mentioned.

  Although the said organic solvent at the time of manufacturing the polyimide of this invention is not specifically limited, For example, the organic solvent illustrated when manufacturing the polyamic acid of this invention mentioned above is mentioned.

  The reaction temperature when producing the polyimide of the present invention (heating temperature for dehydrating and ring-closing the polyamic acid in the method (A) or (B) above) varies depending on the diamine compound and tetracarboxylic acids used, but It is preferable to produce the polyamic acid by stirring at 150 to 250 ° C.

  Although the average degree of polymerization of the polyimide of this invention is not specifically limited, Preferably it is a number of 2-5000. Further, the weight average molecular weight is not particularly limited as long as it is within the above-mentioned average degree of polymerization, but if it is too low, the heat resistance may be insufficient, and if it is too high, the solvent solubility may be deteriorated. 1000000 is preferable and 10000-500000 is more preferable.

As the diamine compound used for the polyamic acid of the present invention and the polyimide of the present invention, an amine compound other than the diamine compound represented by the above general formula (I) may be used in combination, for example, in JP 2010-189578 A Aliphatic diamine compounds, aromatic diamine compounds and 9,9-bis (4-aminophenyl) fluorenes described in paragraphs [0023] to [0026] and paragraph [0018] of JP 2010-235859 A, and A derivative in which a substituent is introduced into the 9,9-bis (4-aminophenyl) fluorene skeleton may be used in combination.
When the diamine compound represented by the general formula (I) and an amine compound other than the diamine compound represented by the general formula (I) are used in combination, the amount of the diamine compound represented by the general formula (I) is as described above. Even if a small amount of the diamine compound represented by the general formula (I) is added, the amount used is not particularly limited because the effect of reducing the viscosity of the polyamic acid is high. However, if the amount used is too small, the viscosity of the polyamic acid may increase or Since the strength may be weakened, the amount of the diamine compound represented by the general formula (I) is preferably 50% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, and 100% by mass. Is most preferred.

  Since the polyimide of the present invention has high heat resistance, high transparency, and high strength, it can be formed by various molding methods such as solution casting, press, injection molding and the like often used for film molding or sheet molding. It is. For this reason, the polyimide of the present invention can be preferably used for applications such as films or sheets of interlayer insulating materials (interlayer insulating films), sealing materials, color filters and electronic circuit insulating materials, Among these, it can be more preferably used as an optical film or an optical sheet used as a display material for various displays such as a liquid crystal display, an organic EL display, and a plasma display. Moreover, it can be used for a fiber reinforced composite material, an adhesive agent, etc. as uses other than a film or a sheet | seat.

Next, the novel diamine compound of the present invention will be described. In addition, about the point which is not demonstrated especially, the description in the polyamic acid and polyamide of this invention is applied suitably.
The novel diamine compound of the present invention is a compound represented by the above general formula (I ′), and among the compounds represented by the above general formula (I), compounds having r = 1 to 4 are applicable.

  As the novel diamine compound of the present invention represented by the general formula (I ′), among the compounds represented by the general formula (I), the compound No. 1 exemplified as the compound of r = 1. 3, no. 4, no. 29-No. 47, but is not limited to these compounds.

  Among these diamine compounds, since the raw materials are easily available, the productivity is good, and the storage stability is excellent, X, Y, Z, k, p, x and y in the general formula (I ′) are the above general formulas. The diamine compound which is the same range as (I) is preferable. In addition, as r in the said general formula (I '), 1 or 2 and especially 1 are preferable. When r is 1 or more, Z is an alkyl group having 1 to 10 carbon atoms or an aryl group having 6 to 20 carbon atoms, preferably an alkyl group having 1 to 10 carbon atoms, more preferably a methyl group. preferable.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further in detail, this invention is not limited to these Examples etc. In Examples and Comparative Examples, “part” means “part by mass”. Examples 1-1 to 1-4 showed production examples of diamine compounds represented by the above general formula (I) (Examples 1-3 and 1-4 are production examples of novel diamine compounds). .) Examples 2-1 to 2-5 showed the manufacture example of the polyamic acid of this invention using the diamine compound represented by the said general formula (I). Comparative Examples 2-1 to 2-3 showed production examples of comparative polyamic acids. Examples 3-1 to 3-5 and comparative examples 3-1 and 3-2 show production examples of the polyimide and comparative polyimide of the present invention, respectively. Examples 4-1 to 4-5 and Comparative Example 4-2 showed the performance test of the polyimide of the present invention and the performance test of the comparative polyimide, respectively.

[Example 1-1] Production of 1,1-bis (4-aminophenyl) -3,3-dimethylindane (Compound No. 1):
In a 300 ml four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube and Dean-Stark azeotropic distillation apparatus, 10.0 g of 3,3-dimethyl-1-indanone, 16.1 g of aniline hydrochloride and 34.9 g of aniline were added. The mixture was stirred and stirred at 120 to 185 ° C. under a nitrogen flow, and water produced was discharged out of the system while the aniline was refluxed, and reacted for 10 hours. After completion of the reaction, the mixture was cooled to 25 ° C., neutralized by adding 10.3 g of a 48% aqueous sodium hydroxide solution and 50 g of water, added with 100 g of ethyl acetate, and then added water until the aqueous layer became neutral. 100 g was used and washed with water three times. The organic layer was distilled under reduced pressure to remove ethyl acetate and unreacted aniline, followed by separation and purification by silica gel column chromatography (developing solvent; ethyl acetate: n-hexane = 1: 1), and the solvent was distilled under reduced pressure. After leaving and drying at 80 ° C. for 4 hours, 4.02 g of a reddish brown solid was obtained. As a result of various analyses, the solid was obtained as a target compound No. 1 (yield 20%).

(result of analysis)
(1) Chemical shift (ppm) of ¹ H-NMR (DMSO-d6: 35 ° C.)
1.14 (s: 6H), 2.68 (s: 2H), 4.71-4.90 (m: 4H), 6.44 (d: 4H), 6.70 (d: 4H), 6 .79 (d: 1H), 7.08-7.28 (m: 3H)
(2) IR spectrum (cm ^-1 )
3433, 3349, 3216, 3026, 2953, 2861, 1621, 1511, 1475, 1449, 1381, 1361, 1283, 1185, 1131, 1079, 1015, 828, 763

[Example 1-2] Production of 1,1-bis (4-aminophenyl) -3-phenylindane (Compound No. 2):
A 300 ml four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube and Dean-Stark azeotropic distillation apparatus was charged with 10.0 g of 3-phenyl-1-indanone, 10.0 g of 35% hydrochloric acid and 35.8 g of aniline, and nitrogen. Under flow, the mixture was stirred at 120 to 185 ° C., and water produced while the aniline was refluxed was discharged out of the system and reacted for 10 hours. After completion of the reaction, the mixture was cooled to 25 ° C., neutralized by adding 7.9 g of a 48% aqueous sodium hydroxide solution and 50 g of water, 100 g of ethyl acetate was added, and 100 g of water was used until the aqueous layer became neutral. Washed three times with water. The organic phase was distilled under reduced pressure to remove ethyl acetate and unreacted aniline, followed by separation and purification by silica gel column chromatography (developing solvent; ethyl acetate: n-hexane = 1: 1), and the solvent was distilled under reduced pressure. After leaving and drying at 80 ° C. for 4 hours, 2.60 g of a reddish brown solid was obtained. As a result of various analyses, the solid was obtained as a target compound No. 2 (yield 14%).

(result of analysis)
(1) Chemical shift (ppm) of ¹ H-NMR (DMSO-d6: 35 ° C.)
2.54-2.71 (m: 1H), 2.97-3.14 (m: 1H), 3.85-4.17 (m: 1H), 4.76-5.02 (m: 4H) ), 6.36-7.40 (m: 17H)
(2) IR spectrum (cm ^-1 )
3438, 3360, 3217, 3025, 2972, 2867, 1728, 1621, 1512, 1469, 1454, 1372, 1279, 1184, 1155, 1129, 1082, 1043, 827, 758, 702

[Example 1-3] Production of 1,1-bis (4-amino-3-methylphenyl) -3,3-dimethylindane (Compound No. 3):
In a 300 ml four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube, and Dean-Stark azeotropic distillation apparatus, 13.1-g 3,3-dimethyl-1-indanone, 52.7 g o-toluidine and 17.0 g 35% hydrochloric acid Was stirred at 125 to 200 ° C. under a nitrogen flow, and water produced while the o-toluidine was refluxed was discharged out of the system and reacted for 15 hours. After cooling to 25 ° C., neutralize by adding 13.5 g of 48% aqueous sodium hydroxide and 50 g of water, add 100 g of toluene, and then use 100 g of water until the aqueous layer becomes neutral in this organic layer, Washed three times with water. Toluene and unreacted toluidine were distilled off from the organic layer by distillation under reduced pressure, followed by separation and purification by silica gel column chromatography (developing solvent; ethyl acetate: n-hexane = 1: 1). A clear brown solid was obtained. As a result of various analyses, the solid was obtained as a target compound No. 3 (yield 20%).

(result of analysis)
(1) Chemical shift (ppm) of ¹ H-NMR (DMSO-d6: 35 ° C.)
1.10 (s: 6H), 1.95 (s: 6H), 2.66 (s: 2H), 4.57 (br: 4H), 6.42-6.48 (m: 2H), 6 .52-6.58 (m: 2H), 6.68 (s: 2H), 6.80 (d: 1H), 7.09-7.20 (m: 3H)
(2) IR spectrum (cm ^-1 )
3446, 3365, 3281, 3015, 2952, 2893, 1622, 1504, 1475, 1449, 1406, 1380, 1361, 1286, 1154, 1079, 1079, 1031, 999, 977, 890, 821, 761, 741

[Example 1-4] Production of 1,1-bis (4-amino-3-methylphenyl) -3-phenylindane (Compound No. 4):
A 300 ml four-necked flask equipped with a stirrer, thermometer, nitrogen inlet tube and Dean-Stark azeotropic distillation apparatus was charged with 10.0 g of 3-phenyl-1-indanone, 30.9 g of o-toluidine and 10.0 g of 35% hydrochloric acid. The mixture was stirred at 125 to 200 ° C. under a nitrogen flow and reacted for 15 hours while refluxing o-toluidine. After cooling to room temperature, neutralize by adding 48 g of 48% aqueous sodium hydroxide and 50 g of water, add 100 g of toluene, and then wash with water three times using 100 g of water until the aqueous layer becomes neutral. It was. Toluene and unreacted toluidine were distilled off from the organic layer by distillation under reduced pressure, and separation and purification were performed by silica gel chromatography (developing solvent; ethyl acetate: n-hexane = 1: 1). A brown transparent solid was obtained. As a result of various analyses, the solid was obtained as a target compound No. 4 was confirmed. (Yield 11%)

(result of analysis)
(1) Chemical shift (ppm) of ¹ H-NMR (DMSO-d6: 35 ° C.)
1.85 to 2.01 (m: 6H), 2.53 to 2.74 (m: 1H), 2.93-3.14 (m: 1H), 3.79 to 4.13 (m: 1H) ), 4.53-4.70 (m: 4H), 6.43-7.37 (m: 15H)
(2) IR spectrum (cm ^-1 )
3449, 3372, 3219, 3058, 3020, 2968, 1732, 1623, 1505, 1469, 1454, 1407, 1377, 1286, 1154, 1077, 1032, 994, 889, 819, 756, 702

[Examples 2-1 to 2-4 and Comparative Examples 2-1 and 2-2] Production and evaluation of polyamic acid solutions A-1 to A-4 and comparative polyamic acid solutions a-1 and a-2:
The diamine compound No. obtained in Examples 1-1 to 4 was used. 1-4, commercially available 9,9-bis (4-aminophenyl) fluorene (hereinafter referred to as Comparative Compound No. 1) and commercially available 4,4′-diamino-3,3′-dimethyldiphenylmethane (hereinafter referred to as Comparative) Compound No. 2) was mixed with γ-butyrolactone and N-methylpyrrolidinone in the amounts (units: parts by mass) shown in Table 1 below, stirred for 2 hours at 25 ° C. and dissolved, and then pyromerit An acid anhydride (hereinafter referred to as PMDA) was added in the amount (unit: part by mass) shown in Table 1 below, and the mixture was stirred at 25 ° C. for 2 hours. -1 and a-2 were produced.

[Example 2-5 and Comparative Example 2-3] Production and evaluation of polyamic acid solution A-5 and comparative polyamic acid solution a-3:
Diamine compound no. 3 and comparative compound no. 1 were prepared in γ-butyrolactone and N-methylpyrrolidinone at the blending amounts (unit: parts by mass) shown in Table 1 below, and stirred and dissolved at 25 ° C. for 2 hours. When 4′-biphenyltetracarboxylic dianhydride (hereinafter referred to as BPDA) was added in the amount (unit: part by mass) described in Table 1 below, the mixture was stirred at 25 ° C. for 6 hours to produce a solution-like polyamic acid. In Example 2-5, BPDA was completely dissolved to obtain polyamic acid A-5, but in Comparative Example 2-3, the solution was remarkably thickened, so that BPDA was not completely dissolved and polyamic acid was obtained. There wasn't.

Viscosity About the solution-like polyamic acid obtained in Examples 2-1 to 2-5 and Comparative Examples 2-1 and 2-2, the viscosity at 25 ° C. with a TV-20 viscometer manufactured by Toki Sangyo Co., Ltd. mPa · s) was measured. The results are shown in Table 1.

From the results of Table 1 above, when comparing the polyamic acid A-1 to A-4 of the present invention obtained by using PMDA as a tetracarboxylic acid and the comparative polyamic acid a-1, the polyamic acid of the present invention is compared. It can be seen that the viscosity is low and the handling property is excellent as compared with the polyamic acid. In particular, the polyamic acid of the present invention in which r in the general formula (III) is 1 has a lower viscosity than the polyamic acid of the present invention in which r is 0.
Similarly, as compared with the case where BPDA was used as the tetracarboxylic acid, the viscosity of the solution a-3 using the comparative compound was too high to obtain a polyamic acid, whereas the diamine compound of the present invention was not obtained. The desired polyamic acid A-5 was obtained in the solution (A-5) using bismuth.

[Examples 3-1 to 3-4 and Comparative examples 3-1 and 3-2] Preparation and evaluation of polyimide films B-1 to B-5 and comparative polyimide films b-1 and b-2:
A glass plate of 10 cm × 10 cm using the polyamic acid solutions (A-1 to A-5, a-1 and a-2) obtained in Examples 2-1 to 2-5 and Comparative Examples 2-1 and 2-2 After coating with an applicator and baking at 100 ° C. for 1 hour, 150 ° C. for 1 hour, and further at 300 ° C. for 1 hour, it is peeled off from the glass and polyimide films B-1 to B-5 and comparative polyimide film b -1 and b-2 were produced. About what obtained the film, the film thickness was measured using the linear gauge LGF-0110L by Mitutoyo Corporation, and it confirmed that it was a uniform film with a film thickness of 58-62 micrometers.

  The film forming property and heat resistance of the obtained polyimide film were evaluated. The results are shown in Table 2.

-Film-forming property The polyimide manufactured about the film-forming property of each polyimide was confirmed visually, and the following <evaluation criteria> evaluated.
<Evaluation criteria>
○: A uniform film without turbidity or foaming was obtained. Δ: A film with turbidity or foaming was obtained. ×: A film could not be formed.

·Heat-resistant
Using "TG / DTA6200" manufactured by SII Nano Technology, the weight loss measurement was performed at a heating rate of 10 ° C / min under a flow of nitrogen of 100 ml / min, and a 5.0% weight loss temperature (Td5) was determined for each polyimide film. Asked about.

In Examples 4-1 to 4-5, good films (polyimide films B-1 to B-5) were obtained, but in Comparative Example 4-1, turbidity and cracking occurred after heating at 150 ° C. for 1 hour. Since it occurred and was damaged, a polyimide film (comparative polyimide film b-1) could not be obtained. In Comparative Example 4-2, although a polyimide film was formed (Comparative polyimide film b-2), foaming was confirmed in some places and a good film could not be obtained.
Moreover, while the polyimide films B-1 to B-5 obtained in Examples 4-1 to 4-5 had high Td5 and excellent heat resistance, the comparative polyimide film b-2 had poor Td5. Therefore, there may be a problem in applications where strength is required.

  From the above, it is clear that the polyimide of the present invention is excellent in film forming property and heat resistance, the polyamic acid as a precursor thereof is excellent in handling properties, and the diamine compound as a raw material is industrially useful.

Claims (5)

A polyamic acid obtained by polycondensation of a diamine compound represented by the following general formula (I) and a tetracarboxylic acid or tetracarboxylic dianhydride having 6 to 24 carbon atoms.

(In the formula, X, Y and Z are each independently an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, or 6 to 20 carbon atoms which may be substituted with a halogen atom. An aryloxy group having 6 to 20 carbon atoms which may be substituted with a halogen atom, an arylthio group having 6 to 20 carbon atoms which may be substituted with a halogen atom, or a halogen atom An arylalkenyl group having 8 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms which may be substituted with a halogen atom, or a complex having 2 to 20 carbon atoms which may be substituted with a halogen atom Represents a cyclic group or a halogen atom,
The methylene group in the alkyl group and arylalkyl group and the direct bond in the aryl group may be interrupted by an unsaturated bond, -O- or -S-, and X is a ring between adjacent Xs. May be formed,
k represents a number from 0 to 4, p represents a number from 0 to 8, r represents a number from 0 to 4, x represents a number from 0 to 4, y represents a number from 0 to 4, The total number of x and y is 2 to 4, and any optical isomer may be used if it exists. ) The polyamic acid of Claim 1 which has a unit represented by the following general formula (III).

(In the formula, X, Y, Z, k, p, r, x and y are the same as those in the general formula (I), and A
Is a tetracarboxylic acid residue having 2 to 20 carbon atoms. ) A polyimide having a unit represented by the following general formula (IV).

(In the formula, X, Y, Z, k, p, r, x, y and A are the same as those in the general formula (III).)   A film or sheet formed using the polyimide according to claim 3. A diamine compound represented by the following general formula (I ′).

(In the formula, X, Y and Z are each independently an alkyl group having 1 to 10 carbon atoms which may be substituted with a halogen atom, or 6 to 20 carbon atoms which may be substituted with a halogen atom. An aryloxy group having 6 to 20 carbon atoms which may be substituted with a halogen atom, an arylthio group having 6 to 20 carbon atoms which may be substituted with a halogen atom, or a halogen atom An arylalkenyl group having 8 to 20 carbon atoms, an arylalkyl group having 7 to 20 carbon atoms which may be substituted with a halogen atom, or a complex having 2 to 20 carbon atoms which may be substituted with a halogen atom Represents a cyclic group or a halogen atom,
The methylene group in the alkyl group and arylalkyl group and the direct bond in the aryl group may be interrupted by an unsaturated bond, -O- or -S-, and X is a ring between adjacent Xs. May be formed,
k represents a number from 0 to 4, p represents a number from 0 to 8, r represents a number from 1 to 4, x represents a number from 0 to 4, y represents a number from 0 to 4, The total number of x and y is 2 to 4, and any optical isomer may be used if it exists. )