JP2009067939A - Polyamic acid and imidized polymer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyamic acid giving an imidized polymer which has a high refractive index, excellent transparency, excellent heat resistance and a specific structure. <P>SOLUTION: Provided is a polyamic acid having a structure represented by general formula (1) [wherein, R is a tetravalent organic group; R<SP>1</SP>groups are each independently a 1 to 3C alkyl group; (a) and (a) are each independently an integer of 0 to 4; (m) is an integer of 1 to 100,000]. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyamic acid and an imidized polymer. More specifically, the present invention relates to a polyamic acid and an imidized polymer having a high refractive index and excellent heat resistance.

  Polyimides have many higher-order structures consisting of cyclic structures such as heterocycles and aromatic rings, molecular chains are difficult to move even at high temperatures, have many higher-order bonds such as double bonds, and interatomic bond energy The heat resistance of polyimide is different from that of various plastics for the reasons that the heterocycle and aromatic ring interact with each other in the polymer molecule and form a CT (Charge Transfer) complex and the cohesion is large. Among them, it is ranked highest.

  Furthermore, polyimide not only has excellent heat resistance, but also has high strength, high elasticity, excellent mechanical properties, high insulation, low dielectric properties, and excellent electrical properties, as well as chemical resistance, radiation resistance, and flame resistance. Is also excellent.

  In recent years, photosensitive polyimides have also been developed. Ultra-highly integrated semiconductors, tough and strong adhesive polyimides are used in space transportation machines, highly transparent polyimides are used in optical communication equipment, and injection moldable polyimides are used in automobiles. Used in heat-resistant sliding parts such as parts.

  As an example of using a polyimide having the above characteristics for optical applications, an example using a polyimide using a diacid anhydride containing a sulfur atom and a diamine not containing a sulfur atom as an optical waveguide (Patent Document 1) ; Example using a polyimide using a diacid anhydride containing no sulfur atom and a diamine containing a sulfur atom as a liquid crystal alignment film (Patent Document 2); Highly refracting a mixture of polyimide having a specific structure and titanium oxide particles Example (Patent Document 3) used as a rate material; and Example using a mixture of polyamic acid not containing a sulfur atom, titanium oxide particles and other specific compounds as a positive photosensitive resin composition (Patent Document 4) Etc. are known.

JP 2004-131684 A JP-A-5-263077 JP 2001-354853 A JP 2005-208465 A

  In an example in which sulfur was introduced into a dianhydride (Patent Document 1), the refractive index was 1.67 to 1.72, but the transparency with visible light (400 to 700 nm) was insufficient. The example (Patent Document 2) used as the liquid crystal alignment film pays attention to the conductivity of polyimide, and there is no description about the refractive index. The invention described in Patent Document 3 uses a polyamic acid obtained by reacting a dianhydride having a specific structure with a diamine having a specific structure. In the diamine used in the invention described in Patent Document 3, the benzene rings are bonded mainly by an ether group (—O—), and only two types having one thioether group (—S—) are described. ing.

  An object of the present invention is to provide a polyamic acid and an imidized polymer that give an imidized polymer having a specific structure having a high refractive index, excellent transparency, and excellent heat resistance.

  In order to achieve the above-mentioned object, the present inventors have conducted intensive research, an aromatic diamine having a sulfide group and a sulfone group introduced at a specific position, an aliphatic or alicyclic tetracarboxylic dianhydride, and a sulfur-containing product. The present inventors have found that an imidized polymer having a high refractive index, high transparency, and excellent heat resistance can be obtained by combining an acid dianhydride, thereby completing the present invention.

［式（１）中、Ｒは４価の有機基を示し、Ｒ^１はそれぞれ独立して炭素数１〜３のアルキル基を示し、ａはそれぞれ独立して０〜４の整数を示し、ｍは１〜１０００００の整数を示す。］
２．下記一般式（２）で示される構造を有するイミド化重合体。

［式（２）中、Ｒ^１はそれぞれ独立して炭素数１〜３のアルキル基を示し、ａはそれぞれ独立して０〜４の整数を示し、Ｒは４価の有機基を示し、ｍは１〜１０００００の整数を示す。］ That is, the present invention provides the following polyamic acid and imidized polymer.
1. A polyamic acid having a structure represented by the following general formula (1).

[In the formula (1), R represents a tetravalent organic group, each R ¹ independently represents an alkyl group having 1 to 3 carbon atoms, a represents each independently an integer of 0 to 4, m Represents an integer of 1 to 100,000. ]
2. An imidized polymer having a structure represented by the following general formula (2).

[In Formula (2), R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms, a represents each independently an integer of 0 to 4, R represents a tetravalent organic group, m Represents an integer of 1 to 100,000. ]

According to the present invention, by using a diamine compound having a diphenylsulfone skeleton into which a sulfur atom is introduced, a high refractive index (a refractive index at a wavelength of 633 nm is 1.733 at the maximum) and high heat resistance are achieved.
ADVANTAGE OF THE INVENTION According to this invention, the imidized polymer suitable for the optical member by which high refractive index, high transparency, and also high heat resistance are requested | required, and the polyamic acid which is the manufacturing raw material can be provided.

I. The polyamic acid having the structure represented by the general formula (1) The polyamic acid of the present invention has the structure represented by the following general formula (1), and its refractive index (25 ° C., wavelength 400 to 700 nm) is very high. In addition, a polymer having a high refractive index and excellent transparency and heat resistance can be formed.

In the formula (1), R represents a tetravalent organic group, and specifically corresponds to a residue obtained by removing an anhydride group from an aliphatic, alicyclic or aromatic tetracarboxylic dianhydride. Since the polymer obtained is excellent in transparency, it is preferably a residue of an alicyclic tetracarboxylic dianhydride. Moreover, since R has a high refractive index, it preferably contains a sulfur atom.
R ¹ each independently represents an alkyl group having 1 to 3 carbon atoms, a is the number of substitutions of the group R ¹ , and each independently represents an integer of 0 to 4. a is preferably 0.
m represents an integer of 1 to 100,000, and is preferably an integer of 10 to 10,000.

上記式（３）及び（４）中、Ｒ^１、ａ及びＲは、一般式（１）で説明した通りであるため、ここでは省略する。 (A) Production of polyamic acid having the structure represented by the general formula (1) The polyamic acid of the present invention includes a diamine represented by the following general formula (3) and a tetracarboxylic acid dicarboxylic acid represented by the following general formula (4). Obtained by reacting anhydride.

In the above formulas (3) and (4), R ¹ , a, and R are as described in the general formula (1), and thus are omitted here.

(B) Diamine represented by the general formula (3) The diamine represented by the general formula (3) is a known compound and can be produced by a known production method.
In the general formula (3), it is preferable to have a structure represented by the following general formula (3-1) in which two sulfide groups are each substituted at the p-position with respect to the sulfone group.

  The diamine represented by the general formula (3), for example, as shown by the following reaction formula, reacts anhydrous potassium carbonate with an amino-substituted thiophenol derivative at a temperature of room temperature to 200 ° C. in an aprotic polar solvent, A potassium salt of an amino-substituted thiophenol derivative is synthesized. A diamine compound represented by the general formula (3) can be produced by adding a dihalogen-substituted diphenylsulfone derivative thereto.

  In addition, the polyamic acid of this invention may contain diamine other than the diamine which has a structure shown by the said General formula (3). That is, in addition to the diamine represented by the general formula (3), a diamine that does not contain a sulfur atom can be used in combination as long as the effects of the present invention are not impaired. Examples of the diamine not containing a sulfur atom include p-phenylenediamine, m-phenylenediamine, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylethane, 4,4′-diaminodiphenyl sulfide, 4, 4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3-dimethyl-4,4'-diaminobiphenyl, 4,4'-diaminobenzanilide, 3,4'- Diaminodiphenyl ether, 3,3′-diaminobenzophenone, 3,4′-diaminobenzophenone, 4,4′-diaminobenzophenone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-Aminophenoxy) phenyl] hexafluoropropyl Pan, 2,2-bis (4-aminophenyl) hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] sulfone, 1,4-bis (4-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1,3-bis (3-aminophenoxy) benzene, 9,9-bis (4-aminophenyl) -10-hydroanthracene, 9,9-bis (4-amino) Phenyl) fluorene, 4,4′-methylene-bis (2-chloroaniline), 2,2 ′, 5,5′-tetrachloro-4,4′-diaminobiphenyl, 2,2′-dichloro-4,4 '-Diamino-5,5'-dimethoxybiphenyl, 3,3'-dimethoxy-4,4'-diaminobiphenyl, 4,4'-(p-phenylenediisopropylidene) bisaniline , 4,4 '- (m- phenylene-isopropylidene) can be mentioned bisaniline.

In addition to the above-mentioned diamine not containing sulfur atoms, aromatic diamines having heteroatoms such as diaminotetraphenylthiophene; 1,1-metaxylylenediamine, 1,3-propanediamine, tetramethylenediamine, pentamethylenediamine , Hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, 4,4-diaminoheptamethylenediamine, 1,4-diaminocyclohexane, isophoronediamine, tetrahydrodicyclopentadienylenediamine, hexahydro-4,7 -Aliphatic or alicyclic diamines such as methanoin danylene dimethylene diamine and tricyclo [6,2,1,0 ^2.7 ] -undecylenedimethyl diamine may be used in combination.

  Among the diamines used for producing the polyamic acid of the present invention, the proportion of the diamine represented by the general formula (3) is preferably 50 mol% or more, more preferably 80 mol% or more, and high refraction. In order to achieve the rate, it is particularly preferably 100 mol%.

(C) Tetracarboxylic dianhydride represented by the general formula (4) The acid anhydride used in the present invention is represented by the general formula (4). In the formula (4), R corresponds to a residue obtained by removing the anhydride group from tetracarboxylic dianhydride. Such compounds include aliphatic, alicyclic or aromatic tetracarboxylic dianhydrides, preferably aliphatic and alicyclic tetracarboxylic dianhydrides, and the resulting polymer has excellent transparency. In particular, alicyclic tetracarboxylic dianhydride is preferable.

Examples of the aliphatic and alicyclic tetracarboxylic dianhydrides include, for example, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 1,2,3,4 -Cyclopentanetetracarboxylic dianhydride, 4,10-dioxatricyclo [6.3.1.0 ^2,7 ] dodecane-3,5,9,11-tetraone, 1,2,4,5- Cyclohexanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic acid dihydrate, 3,5,6-tricarboxynorbornane-2-acetic acid dianhydride, 2,3,4,5-tetrahydrofurantetra Carboxylic dianhydride, 1,3,3a, 4,5,9b-hexahydro-5-tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3- Zeon, -(2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic dianhydride, bicyclo [2,2,2] -oct-7-ene-2,3,5 And aliphatic and alicyclic tetracarboxylic dianhydrides such as 1,6-tetracarboxylic dianhydride. Among these, butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 4,10-dioxatricyclo [6.3.1.0 ^2,7 ] dodecane- 3,5,9,11-tetraone, 2,3,5-tricarboxycyclopentyl acetic acid dianhydride, 5- (2,5-dioxotetrahydrofural) -3-methyl-3-cyclohexene-1,2-dicarboxylic acid Acid dianhydride and 1,3,3a, 4,5,9b-hexahydro-5-tetrahydro-2,5-dioxo-3-furanyl) -naphtho [1,2-c] -furan-1,3-dione 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 4,10-dioxatricyclo [6.3.1.0 ^2,7 ] dodecane-3,5,9,11-tetraone 1, 2, 4, 5-cyclohexanetetracarboxylic dianhydride is particularly preferred.

  Specific examples of the aromatic tetracarboxylic dianhydride include, for example, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4 ′. -Biphenylsulfone tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 3,3 ', 4,4 '-Biphenyl ether tetracarboxylic dianhydride, 3,3', 4,4'-dimethyldiphenylsilane tetracarboxylic dianhydride, 3,3 ', 4,4'-tetraphenylsilane tetracarboxylic dianhydride 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenyl sulfide dianhydride, 4,4′-bis (3,4-dicarbo) Ciphenoxy) diphenylsulfone dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) diphenylpropane dianhydride, 4,4 ′-(hexafluoroisopropylidene) bis (phthalic acid) dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, bis (phthalic acid) phenylphosphine oxide dianhydride, p-phenylene-bis (triphenylphthalic acid) dianhydride, m-phenylene-bis Aromatic tetra such as (triphenylphthalic acid) dianhydride, bis (triphenylphthalic acid) -4,4′-diphenyl ether dianhydride, bis (triphenylphthalic acid) -4,4′-diphenylmethane dianhydride Carboxylic dianhydrides can be mentioned. Among these, pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenylsulfone tetracarboxylic dianhydride, 4 4,4 '-(Hexafluoroisopropylidene) bis (phthalic acid) dianhydride and 3,3', 4,4'-biphenyltetracarboxylic dianhydride are preferred.

  In addition, since a polyamic acid having a higher refractive index can be obtained, it is also preferable to use a tetracarboxylic dianhydride containing a sulfur atom. Examples of sulfur atom-containing acid anhydrides include 4,4 '-[p-thiobis (phenylene-sulfanyl)] diphthalic anhydride.

(D) Reaction of the diamine represented by the general formula (3) and the tetracarboxylic dianhydride represented by the general formula (4) Generally, in an aprotic organic solvent such as N-methyl-2-pyrrolidone, a diamine compound And the acid dianhydride are stirred and mixed, whereby the polyamic acid of the present invention can be obtained as a solution. For example, a diamine compound may be dissolved in an organic solvent, and acid dianhydride may be added thereto and mixed with stirring. Alternatively, a mixture of a diamine compound and acid dianhydride may be added to an organic solvent and mixed with stirring. May be. The reaction is usually performed at a temperature of 100 ° C. or lower, preferably 80 ° C. or lower, under normal pressure. However, the reaction may be performed under pressure or under reduced pressure as necessary. The reaction time varies depending on the diamine compound and acid dianhydride used, the organic solvent, the reaction temperature, etc., but is usually in the range of 4-24 hours.

  The polyamic acid of the present invention gives a polymer having a high refractive index, excellent transparency and excellent heat resistance (imidized polymer) by dehydrating and ring-closing this by an imidization reaction. It is suitable as a material for manufacturing required optical members.

式（２）中のＲ^１、ａ、Ｒ及びｍは、一般式（１）と同様であるためここでは説明を省略する。 II. The imidized polymer represented by the general formula (2) The imidized polymer of the present invention has a structure represented by the following general formula (2).

Since R ¹ , a, R and m in the formula (2) are the same as those in the general formula (1), description thereof is omitted here.

  The imidized polymer of the present invention is prepared by heating the polyamic acid of the present invention at a temperature of 80 to 300 ° C. in a nitrogen atmosphere for 1 to 5 hours, whereby the polyamic acid is imidized, and the general formula ( It becomes an imidized polymer having the structure represented by 2).

  The imidized polymer of the present invention has a refractive index at a wavelength of 633 nm of usually 1.60 or more, preferably 1.68 or more, more preferably 1.70 or more.

  The imidized polymer of the present invention is suitable as an optical member that requires a high refractive index, excellent transparency, and excellent heat resistance. Examples of the optical member using the imidized polymer of the present invention include a light collecting material for a solid-state imaging device, a light collecting material for a recording disk, and the like.

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

Synthesis example 1
4,4'-bis (4-aminophenylenesulfanyl) diphenylsulfone

  In a reaction vessel equipped with a stirrer, reflux condenser, Dean-Stark trap and nitrogen introduction tube, p-aminothiophenol (15.0 g, 0.120 mol) and anhydrous potassium carbonate (8.40 g, 0.060 mol), 4 , 4′-Dichlorodiphenylsulfone (14.4 g, 0.050 mol) was added and reacted at 150 ° C. for 1 hour and 170 ° C. for 2 hours. The reaction solution was cooled to room temperature, dehydrated ethanol (200 mL) was added, and the mixture was heated to reflux for 1 hour. Thereafter, the reaction solution was returned to room temperature, and the reaction solution was poured into cold water (500 mL) to obtain a precipitate. The precipitate was recrystallized from ethanol to obtain a white solid.

Yield: 19.7g
Yield: 84.8%
Melting point: 218.6 ° C. (DSC)
¹ H-NMR (300 MHz, DMSO-d ₆ , ppm): 5.56 (s, 4H), 6.63-6.66 (d, 4H), 7.07-7.11 (d, 4H), 7.15-7.18 (d, 4H), 7.68-7.71 (d, 2H)
FTIR (KBr, cm ⁻¹ ): 3475.1, 3378.7, 1623.8, 1592.9, 1573.6, 1496.5, 1396.2, 1315.2, 1157.1, 1079.9, 1006 .7, 829.2, 763.7
_{Calcd: C 24 H 20 N 2 O} 2 S 3: C, 62.04%; H, 4.34%; N, 6.03%
Measurement: C, 62.28%; H, 4.33%; N, 5.79%

Synthesis example 2
4,4 ′-[p-thiobis (phenylene-sulfanyl)] diphthalic anhydride

  In a reaction vessel equipped with a stirrer, a reflux condenser and a nitrogen introduction tube, 4,4′-thiobisbenzenethiol (5.00 g, 0.02 mol) and 4-bromophthalic anhydride (10.00 g, 0.044 mol) , Anhydrous potassium carbonate (6.08 g, 0.044 mol), and N, N-dimethylformamide (hereinafter referred to as DMF) (100 mL) were added and reacted at 120 ° C. for 12 hours. The reaction solution was returned to room temperature, and a white solid was collected by filtration and dried under reduced pressure at 160 ° C. for 24 hours. Distilled water (100 mL) and concentrated hydrochloric acid (100 mL) were added to the obtained white solid, and the mixture was heated and stirred for 3 hours. The obtained white solid was collected by filtration and heated at 180 to 190 ° C. for 3 hours to obtain a yellow solid.

Yield: 7.8g
Yield: 71.9%
Melting point: 175.2 ° C (DSC)
FT-IR (KBr, cm < ^-1 >): 1847.5, 1778.0, 1604.4, 1473.3, 1326.8, 1257.4, 902.5, 817.7, 732.0
¹ H-NMR (300 MHz, DMSO-d ₆ , ppm): 7.45-7.49 (d, 4H), 7.52 to 7.55 (d, 4H), 7.56 (s, 2H), 7.60-7.63 (d, 2H), 7.83-7.85 (d, 2H)
Calcd _{C 28 H 14 O 6 S 3} : C, 61.98%; H, 2.60%
Measured value C, 62.23%; H, 2.97%

Synthesis example 3
Diphenylsulfone-3,3′-disulfonyl chloride

Diphenylsulfone (23.8 g, 0.11 mol) and sulfonic acid chloride (58 mL, 0.87 mol) were added to a reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen introduction tube, and the reaction solution was stirred at 140 ° C. for 4 hours. did. The reaction solution was cooled to room temperature and poured into cooled distilled water (500 mL) to precipitate a solid. The precipitated solid was collected by filtration, washed with water, and dried under reduced pressure at 80 ° C. for 24 hours. Then, white crystals were obtained by recrystallization with ethyl acetate.
Yield: 32.9g
Yield: 72%
Melting point: 181.0 ° C. (DSC)
¹ H-NMR (300 MHz, CDCl ₃ , ppm): 7.85-7.91 (t, 2H), 8.28-8.36 (m, 4H), 8.61-8.62 (m, 2H) )

Synthesis example 4
Diphenylsulfone-3,3′-dithiol

Anhydrous tin chloride (50 g, 0.22 mol), acetic acid (100 mL), and hydrochloric acid (40 mL) were placed in a reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen introduction tube, and the reaction solution was heated to 90 ° C. Diphenyl sulfone-3,3′-disulfonyl chloride (4.15 g, 0.01 mol) synthesized in Synthesis Example 1 was added thereto and stirred. The reaction was stirred at 90 ° C. for 3 hours and cooled to room temperature. Thereafter, the reaction solution was poured into distilled water (200 mL) containing hydrochloric acid (20 mL). The precipitated solid was collected by filtration. The filtered product was washed with water and dried under reduced pressure at 80 ° C. for 24 hours.
Yield: 2.57g
Yield: 91.0%
Melting point: 107.5 ° C. (DSC)
¹ H-NMR (300 MHz, CDCl ₃ , ppm): 3.64 (s, 2H), 7.34-7.46 (m, 4H), 7.67-7.70 (d, 2H), 7. 81-7.82 (m, 2H)

Synthesis example 5
4,4 '-[m-sulfonylbis (phenylenesulfanyl)] diphthalic anhydride

  In a reaction vessel equipped with a stirrer, a reflux condenser, and a nitrogen introduction tube, diphenylsulfone-3,3′-dithiol (2.82 g, 0.01 mol) synthesized in Synthesis Example 2 and 4-bromophthalic anhydride (5. 00 g, 0.022 mol), anhydrous potassium carbonate (3.04 g, 0.022 mol), and N, N-dimethylformamide (hereinafter referred to as DMF) (50 mL) were added, and the reaction solution was heated to reflux at 120 ° C. for 12 hours. . The white solid produced after cooling to room temperature was collected by filtration and dried under reduced pressure at 160 ° C. for 24 hours. Concentrated hydrochloric acid (50 mL) was added to the obtained white solid and heated, and after cooling to room temperature, it was collected by filtration and washed with water. Thereafter, water was distilled off under reduced pressure and further dried under reduced pressure at 160 to 180 ° C. for 3 hours to obtain a pale yellow solid.

Yield: 4.20g
Yield: 73.1%
Melting point: 193.3 ° C. (DSC)
¹ H-NMR (300 MHz, CDCl ₃ , ppm): 7.57-7.59 (d, 2H), 7.62-7.67 (m, 4H), 7.73-7.78 (d, 2H) ), 7.86-7.90 (d, 2H), 8.10-8.12 (m, 2H)
¹³ C-NMR (75 MHz, CDCl ₃ , ppm): 162.3, 162.1, 148.6, 143.2, 138.9, 134.7, 133.3, 132.7, 132.6, 131 .7, 128.9, 126.3, 123.7
FTIR (KBr, cm ⁻¹ ): 1851.3, 1774.2, 1604.5, 1461.8, 1423.2, 1326.8, 1295.9, 1257.4, 1160.9, 902.5, 732 .8, 686.5, 605.5
_{Calcd: C 28 H 14 N 2 0} 8 S 3: C, 58.53%; H, 2.46%
Measurement: C, 58.19%; H, 273%

<Production of polyamic acid>
Example 1
In a reaction vessel equipped with a nitrogen introduction tube, 4,4′-bis (4-aminophenylenesulfanyl) diphenylsulfone (hereinafter referred to as BADPS) (17.30 g, 40 mmol) synthesized in Synthesis Example 1 was added to N-methyl-2. -Pyrrolidone (hereinafter referred to as NMP) (80 g) was added and stirred at room temperature to completely dissolve. Next, 4,4 ′-[p-thiobis (phenylene-sulfanyl)] diphthalic anhydride (hereinafter referred to as 3SDEA) (21.70 g, 40 mmol) and NMP (25 g) synthesized in Synthesis Example 2 were added, The mixture was stirred at room temperature for 24 hours to obtain an NMP solution of polyamic acid.

Examples 2-5
Instead of 3SDEA used in Example 1, polymerization was carried out in the same manner as in Example 1 except that acid anhydrides shown in Table 1 below were used to obtain NMP solutions of each polyamic acid.

Comparative Example 1
NMP (80 g) was added to bis (p-aminophenyl) ether (hereinafter referred to as ODA) (8.01 g, 40 mmol) in a reaction vessel equipped with a nitrogen introduction tube, and stirred at room temperature for complete dissolution. Next, 1,2,3,4-cyclobutanetetracarboxylic dianhydride (hereinafter referred to as CBDA) (7.84 g, 40 mmol) and NMP (25 g) were added, and the mixture was stirred at room temperature for 24 hours. Of NMP was obtained.

  An IR chart of the polyamic acid obtained in Example 4 is shown in FIG.

<Creation of imidized polymer film>
An NMP solution of polyamic acid produced in Examples and Comparative Examples was dispensed on a 3 inch diameter 3 mm thick fused quartz substrate, spin coated to a thickness of about 8-12 μm, and applied at 280 ° C. in a nitrogen atmosphere. Heating for 1.5 hours gave an imidized polymer film.
An IR chart of the obtained imidized polymer of Example 4 is shown in FIG.

<Characteristic evaluation of imidized polymer film>
The following characteristics were evaluated for the imidized polymer film obtained above. The results are shown in Table 1.

(1) Refractive index Using a Metricon PC-2000 type prism coupler, the refractive index at a wavelength of 633 nm of the imidized polymer film obtained above was measured.

(2) Transmittance Using a U-3500 self-recording spectrophotometer manufactured by Hitachi, Ltd., transmittance (%) at a wavelength of 450 nm per 10 μm thickness of the imidized polymer film obtained above was measured. .

(3) Heat resistance A 5% weight loss temperature of the imidized polymer film obtained above was measured using a DSC6300 manufactured by Seiko Instruments Inc. (temperature increase rate: 10 ° C./min, under nitrogen stream). The case where the 5% weight loss temperature was 400 ° C. or higher was evaluated as heat resistance pass (◯).

Abbreviations in Table 1 represent the following.
BADPS: 4,4′-bis (4-aminophenylenesulfanyl) diphenyl sulfone (Synthesis Example 1)
ODA: bis (p-aminophenyl) ether 3SDEA: 4,4 ′-[p-thiobis (phenylene-sulfanyl)] diphthalic anhydride (Synthesis Example 2)
BPDA: sBPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride ODPA: 4,4′-oxydiphthalic dianhydride DPSDA: 4,4 ′-[m-sulfonylbis (phenylenesulfanyl)] Diphthalic anhydride (Synthesis Example 5)
CBDA: 1,2,3,4-cyclobutanetetracarboxylic dianhydride

  From the results of Table 1, the polyamic acid represented by the general formula (1) has a very high refractive index of 1.700 to 1.733 at a wavelength of 633 nm, a high transmittance at 450 nm, excellent heat resistance, and high It turns out that it is useful as a manufacturing material of the optical member which requires a refractive index and the outstanding heat resistance.

The polyamic acid of the present invention is useful as a raw material for producing optical members that require high refractive index, high transparency, and high heat resistance.
The imidized polymer of the present invention is useful as, for example, a coating material for a high refractive index material and a high refractive index material for an antireflection film, a material for improving the sensitivity of optical waveguides, various lenses, solid-state imaging devices and recording disks.

4 is an FT-IR chart of the polyamic acid obtained in Example 4. 4 is an FT-IR chart of an imidized polymer obtained by imidizing the polyamic acid obtained in Example 4. FIG.

Claims (2)

A polyamic acid having a structure represented by the following general formula (1).

[In the formula (1), R represents a tetravalent organic group, each R ¹ independently represents an alkyl group having 1 to 3 carbon atoms, a represents each independently an integer of 0 to 4, m Represents an integer of 1 to 100,000. ] An imidized polymer having a structure represented by the following general formula (2).

[In Formula (2), each R ¹ independently represents an alkyl group having 1 to 3 carbon atoms, a represents each independently an integer of 0 to 4, R represents a tetravalent organic group, m Represents an integer of 1 to 100,000. ]

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