JP4994672B2 - Aromatic polyamic acid and aromatic polyimide - Google Patents

Description

  The present invention relates to a novel aromatic polyamic acid and a novel aromatic polyimide obtained by dehydrating and ring-closing the same. Specifically, the present invention relates to a novel aromatic polyamic acid obtained by introducing 3,8-diaminodibenzopyranone as a diamine component into a molecule and a novel aromatic polyimide obtained by dehydrating and ring-closing it.

  In general, polyimide resin has excellent heat resistance, chemical resistance, electrical properties, and mechanical properties. Therefore, it is widely used as an electrical and electronic equipment material, especially for electrical insulation materials that require heat resistance. It's being used. Particularly, in recent years, electronic devices have been improved in function, performance, and size, and a polyimide resin that can cope with the reduction in size and weight of electronic components is strongly desired.

  Conventional polyimides are known to have significantly higher moisture absorption, although they have better heat resistance and electrical insulation than other organic polymers. For this reason, it causes various problems such as swelling caused when the flexible printed wiring board is immersed in the solder bath, deterioration of electrical characteristics due to moisture absorption in the air, and poor connection of electronic equipment due to dimensional changes after moisture absorption of polyimide. It was. Therefore, characteristics such as low moisture absorption and low humidity expansion are desired. In addition, since the machining process includes many processes that receive stress and processes that undergo temperature changes, it is desirable that the dimensional change due to stress and temperature changes be small. In order to reduce the dimensional change due to stress, it is effective that the film exhibits high elasticity, and in order to reduce the dimensional change due to temperature change, it is effective to reduce the thermal expansion coefficient of the film.

  Conventionally, in order to obtain a highly elastic polyimide film, it is known that it is effective to use a monomer having high linearity. For example, if only a rigid straight chain such as pyromellitic anhydride and paraphenylenediamine is used, a highly elastic polyimide can be synthesized. However, such a structure is very fragile and the moisture absorption rate increases, so that the hygroscopic expansion coefficient also increases.

Japanese Patent Laid-Open No. 02-225522 JP 2001-11177 A JP 08-217877 A JP 2000-63543 A JP-A-01-261421 WO01 / 28767A1 The Chemical Society of Japan, 1977, (5), 701-705 Journal of Polymer Science Part B, 33, 1907-1915 (1995)

  Against this background, in recent years, there has been an increasing demand for polyimide resins having excellent low moisture absorption and dimensional stability after moisture absorption. For example, Patent Document 1 and Patent Document 2 propose a polyimide that improves hydrophobicity and expresses low hygroscopicity by introducing a fluorine-based resin. There is a drawback of poor adhesion. As for other efforts to reduce moisture absorption, as shown in Patent Document 3 and Patent Document 4 and the like, while exhibiting good characteristics such as low moisture absorption and low thermal expansion coefficient, it is possible to maintain high heat resistance. Not.

  Patent Documents 5 and 6 propose monomers having high heat resistance, high elasticity, and low hygroscopicity. However, since the polyimide resin described here is rigid, its elastic modulus is very high. In recent years, laminates used for flexible printed wiring boards having polyimide as an insulating layer are often used for bending applications such as cellular phones. When applied to such applications, there has been a demand for a polyimide material having an appropriate elastic modulus that is not too rigid while balancing with other physical properties.

  In Non-Patent Document 1 and Non-Patent Document 2, there are reports on polyimide using a diamine having a fluorene skeleton similar to the present invention. However, the polyimide described in these documents does not satisfy the performance for use as a material for precision electrical / electronic equipment.

  Therefore, the present invention solves the above-mentioned conventional problems, has an excellent heat resistance, an appropriate elastic modulus, and realizes low hygroscopicity and low thermal expansion, and an aromatic polyamide as a precursor thereof. The object is to provide acid.

（式中、Ar₁は芳香環を1個以上有する4価の有機基である。） That is, this invention is an aromatic polyamic acid characterized by having 10 mol% or more of a structural unit represented by the following general formula (1).

(In the formula, Ar ₁ is a tetravalent organic group having one or more aromatic rings.)

（式中、Ar₁は芳香環を1個以上有する4価の有機基である。） Furthermore, this invention is an aromatic polyimide characterized by having 10 mol% or more of structural units represented by the following general formula (2).

(In the formula, Ar ₁ is a tetravalent organic group having one or more aromatic rings.)

  Hereinafter, the present invention will be described in more detail.

  A polyamic acid having a structural unit represented by the general formula (1) (hereinafter also referred to as the present polyamic acid) is a polyimide having a structural unit represented by the general formula (2) by curing and imidizing the polyamic acid. (Hereinafter also referred to as the present polyimide), it can be referred to as a precursor of the present polyimide.

In the structural units represented by the general formulas (1) and (2), Ar ₁ is a tetravalent organic group having one or more aromatic rings, such as an aromatic tetracarboxylic acid or an acid dianhydride thereof. An aromatic tetracarboxylic acid residue generated from Therefore, Ar ₁ is understood by describing the aromatic tetracarboxylic acid used. Usually, when synthesizing this polyimide or the polyamic acid having the structural unit, so that the aromatic tetracarboxylic acid dianhydride is used frequently, the preferred Ar ₁ using an aromatic tetracarboxylic dianhydride This will be described below.

  It does not specifically limit as said aromatic tetracarboxylic dianhydride, A well-known thing can be used. Specific examples include pyromellitic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 2 , 3,3 ', 4'-Benzophenonetetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1,2,5,6-tetracarboxylic dianhydride , Naphthalene-1,2,4,5-tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, naphthalene-1,2,6,7-tetracarboxylic dianhydride 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3 , 5,6,7-hexahydronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 2,6-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2, 7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-tetrachloronaphth Len-1,4,5,8-tetracarboxylic dianhydride, 1,4,5,8-tetrachloronaphthalene-2,3,6,7-tetracarboxylic dianhydride, 3,3 ', 4 , 4'-biphenyltetracarboxylic dianhydride, 2,2 ', 3,3'-biphenyltetracarboxylic dianhydride, 2,3,3', 4'-biphenyltetracarboxylic dianhydride, 3, 3 '', 4,4 ''-p-terphenyltetracarboxylic dianhydride, 2,2``, 3,3 ''-p-terphenyltetracarboxylic dianhydride, 2,3,3 ' ', 4' '-p-terphenyltetracarboxylic dianhydride, 2,2-bis (2,3-dicarboxyphenyl) -propane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) ) -Propane dianhydride, bis (2,3-dicarboxyphenyl) ether dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3.4-dicarboxyphenyl) methane dianhydride, Bis (2,3-dicarboxyphenyl) sulfone dianhydride, bis (3,4-dicarboxyphenyl) Nyl) sulfone dianhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, 1,1-bis (3,4-dicarboxyphenyl) ethane dianhydride, perylene-2,3 , 8,9-tetracarboxylic dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, perylene-4,5,10,11-tetracarboxylic dianhydride, perylene-5, 6,11,12-tetracarboxylic dianhydride, phenanthrene-1,2,7,8-tetracarboxylic dianhydride, phenanthrene-1,2,6,7-tetracarboxylic dianhydride, phenanthrene-1 , 2,9,10-Tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine -2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, and the like. Moreover, these can be used individually or in mixture of 2 or more types.

  Among these, pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, naphthalene-2,3,6,7-tetracarboxylic dianhydride, naphthalene-1, 4,5,8-tetracarboxylic dianhydride, 3,3 ", 4,4" -p-terphenyltetracarboxylic dianhydride, 4,4'-oxydiphthalic dianhydride, 3,3'4 At least one aromatic tetracarboxylic acid selected from 4,4′-benzophenonetetracarboxylic dianhydride and bis (2,3-dicarboxyphenyl) sulfone dianhydride is preferred. Among them, pyromellitic dianhydride (PMDA), naphthalene-2,3,6,7-tetracarboxylic dianhydride (NTCDA) and 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride Preferred is one selected from products (BPDA). When selecting tetracarboxylic dianhydride, specifically, select a suitable one by measuring the thermal expansion coefficient, thermal decomposition temperature, glass transition temperature, humidity expansion coefficient, etc. of polyimide obtained by polymerization and heating. Is preferred.

The diamine used in the synthesis of the present polyamic acid or the present polyimide having the structural unit represented by the general formula (1) or (2) is 3,8-diaminodibenzopyranone represented by the following formula (3) , Also referred to as the present aromatic diamine).

  The present polyamic acid or the present polyimide can be advantageously obtained by reacting an aromatic tetracarboxylic dianhydride with a diamine containing 10 mol% or more of the present aromatic diamine.

  The aromatic diamine represented by the formula (3) can be synthesized through the following steps. That is, a step of synthesizing 3,8-dinitrodibenzopyranone by oxidizing the ketone portion of 1,5-dinitrofluorenone to an ester group with peracid (referred to as step-I), and reducing two nitro groups to diamine As the desired 3,8-diaminodibenzopyranone (referred to as Step-II).

  The reaction of Step-I is a kind of Baeyer-Villiger reaction, and this reaction is a well-known personal name reaction in many synthetic literatures, but the reaction when 1,5-dinitrofluorenone is used as a raw material is -The reaction did not proceed at all using the general conditions of the Villiger reaction. Therefore, concentrated sulfuric acid, the only raw material dissolved, was used as a reagent and reaction solvent, and peracid was succeeded in advancing the desired reaction by using a commercially available 30% hydrogen peroxide solution. The reaction of Step-II is to reduce both nitro groups without seeing reduction of the lactone moiety by utilizing the known reaction described in Przemysl Chemiczny, 71, 10, 389-391 (1992). The intended aromatic diamine can be obtained.

  The 3,8-diaminodibenzopyranone thus obtained can be obtained in high purity by collecting the solid that precipitates when the reaction solution of Step-II is filtered while hot and then cooled.

In this invention, 90 mol% or less of other diamine other than that can be used with this aromatic diamine. And it can be set as copolymerization type polyamic acid or a polyimide by it.
The structural unit represented by the general formula (1) or (2) is contained in the polyamic acid or the polyimide in an amount of 10 to 100 mol%, preferably 50 to 100 mol%, more preferably 70 to 100 mol%. Good.

  In addition to the aromatic diamine that gives the structural unit represented by the general formula (1) or (2), the diamine that can be used for the copolymerization is not particularly limited. -Dimethyl-m-phenylenediamine, 2,5-dimethyl-p-phenylenediamine, 2,4-diaminomesitylene, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,5,3 ', 5' -Tetramethyl-4,4'-diaminodiphenylmethane, 2,4-toluenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4 '-Diaminodiphenylethane, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 4 , 4'-diaminodiphenyl sulfide, 3,3'-diaminodi Phenyl sulfide, 4,4′-diaminodiphenyl sulfone, 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenoxy) benzene, benzidine, 3,3'-diaminobiphenyl, 3,3'-dimethyl-4,4'-diaminobiphenyl 3,3'-dimethoxybenzidine, 4,4 "-diamino-p-terphenyl, 3,3" -diamino-p-terphenyl, bis (p-aminocyclohexyl) methane, bis (p-β-amino- t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene, p-bis (1,1-dimethyl-5-amino) Pentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-acrylate) Tert-butyl) toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6 -Diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine and the like.

  Among these, 1,3-bis (3-aminophenoxy) benzene (APB), 1,3-bis (4-aminophenoxy) benzene (TPE-R), 1,4-bis (4-aminophenoxy) benzene (TPE-Q) and the like are preferably used. Moreover, when using these diamines, the preferable usage rate is the range of 0-50 mol% of all the diamine, More preferably, it is the range of 0-30 mol%.

  The aromatic polyamic acid can be produced by a known method in which the aromatic diamine component and the aromatic tetracarboxylic dianhydride component shown above are used in substantially equimolar amounts and polymerized in an organic polar solvent. it can. That is, it is obtained by dissolving an aromatic diamine in an organic polar solvent such as N, N-dimethylacetamide under a nitrogen stream, adding aromatic tetracarboxylic dianhydride, and reacting at room temperature for about 3 hours.

  And this polyimide is obtained by heating and imidating this polyamic acid obtained by making it above. For imidation, this polyamic acid is usually applied on an arbitrary substrate such as copper foil using an applicator, pre-dried at a temperature of 150 ° C or lower for 2 to 20 minutes, and then usually for solvent removal and imidization. The heat treatment is performed at a temperature of about 130 to 360 ° C. for about 2 to 30 minutes.

  The degree of polymerization of the present polyamic acid and the present polyimide is 50,000 to 800,000, preferably 60,000 to 250,000, as the weight average molecular weight (Mw) of the polyamic acid solution. The weight average molecular weight can be measured by GPC.

  The polyamic acid of the present invention can be dehydrated and closed to give a polyimide having excellent heat resistance and low thermal expansion, low moisture absorption, and low moisture absorption. That is, the polyimide of the present invention has a thermal expansion coefficient of 20 ppm / K or less, a heat resistance of 500 ° C. or more (thermal decomposition temperature Td 2%), an elastic modulus of 4 to 10 GPa at 23 ° C., and a moisture absorption rate of 0.7 wt. % And a humidity expansion coefficient of 9 ppm /% RH or less can be exhibited, so that it can have excellent properties such as heat resistance, dimensional stability, elastic modulus and low hygroscopicity. The polyimide of the present invention can be used in various fields including the electric / electronic field by taking advantage of these characteristics, and is particularly useful as an insulating material for a wiring board.

  Hereinafter, the content of the present invention will be specifically described based on examples, but the present invention is not limited to the scope of these examples.

Abbreviations used in Examples and the like are shown below.
・ DADBP: 3,8-diaminodibenzopyranone ・ DAF: 2,7-diaminofluorene ・ PMDA: pyromellitic dianhydride ・ BPDA: 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride ・TPE-Q: 1,4-bis (4-aminophenoxy) benzene, TPE-R: 1,3-bis (4-aminophenoxy) benzene, APB: 1,3-bis (3-aminophenoxy) benzene, DMAc : N, N-dimethylacetamide

Measuring methods and conditions for various physical properties in the examples are shown below.
[Measurement of linear expansion coefficient (CTE)]
A polyimide film with a size of 3 mm x 15 mm is subjected to a tensile test in the temperature range of 30 ° C to 260 ° C at a constant temperature increase rate while applying a 5.0 g load with a thermomechanical analysis (TMA) device, and the polyimide film against the temperature The linear expansion coefficient (ppm / K) was measured from the amount of elongation.

[Measurement of glass transition temperature (Tg)]
The dynamic viscoelasticity of the polyimide film (10mm x 22.6mm) obtained in each example was measured at a rate of 5 ° C / min from 20 ° C to 500 ° C using a dynamic thermal analyzer, and the glass transition The temperature (tan δ maximum value: ° C.) was determined.

[Measurement of tensile modulus]
The polyimide film (12.7 mm × 160 mm) obtained in each example was subjected to a tensile test at a speed of 50 mm / min using a tension tester equipped with a 50 kg load cell, and the tensile elastic modulus (GPa) was obtained.

[Measurement of thermal decomposition temperature (Td2%)]
The weight change when a polyimide film weighing 10 to 20 mg was heated from 30 ° C to 550 ° C at a constant rate with a thermogravimetric analysis (TG) device was measured, and 2% weight loss temperature (Td2% : ° C.).

[Measurement of moisture absorption rate]
4cm x 20cm polyimide films (3 sheets each) are dried at 120 ° C for 2 hours, then left in a constant temperature and humidity chamber at 23 ° C / 50% RH for 24 hours or more. Asked.
Moisture absorption rate (wt%) = [(weight after moisture absorption−weight after drying) / weight after drying] × 100

[Measurement of humidity expansion coefficient (CHE)]
An etching resist layer is provided on a copper foil of a 35 cm x 35 cm polyimide / copper foil laminate, and this is arranged through a mask so that 16 points of 1 mm in diameter are arranged at 10 cm intervals on four sides of a 30 cm square. Exposure and development were performed to obtain a polyimide film for CHE measurement having the above 16 copper foil remaining points. This film was dried at 120 ° C for 2 hours, then left at 23 ° C / 30% RH / 50% RH constant temperature and humidity chamber for at least 24 hours at each humidity, and measured at each humidity measured by a two-dimensional measuring machine. The humidity expansion coefficient (ppm /% RH) was obtained from the dimensional change between the copper foil points.

Examples 1-6
In order to synthesize the polyamic acids A to F, the diamine shown in Table 1 was dissolved in the solvent DMAc with stirring in a 200 ml separable flask under a nitrogen stream. Subsequently, the tetracarboxylic dianhydride shown in Table 1 was added. Thereafter, the solution was stirred at room temperature for 3 hours to carry out a polymerization reaction, thereby obtaining a yellow-brown viscous solution of polyamic acids A to F to be a polyimide precursor. The weight average molecular weight (Mw) of each polyamic acid solution was in the range of about 100,000 to 250,000, and it was confirmed that a polyamic acid with a high degree of polymerization was produced. The solid content and solution viscosity of the polyamic acid are shown in Table 1. Here, the solid content is a weight ratio of the polyamic acid to the total amount of the polyamic acid and the solvent. The solution viscosity was measured using an E-type viscometer.

Comparative Example 1
Polyamic acid G was synthesized in the same manner as in Examples 1 to 6 except that the composition of the raw materials was changed as shown in Table 1, and the same measurement was performed. The results are summarized in Table 1.

Examples 7-12
The polyamide solution of A to F was applied on each copper foil using an applicator so that the film thickness after drying was about 15 μm, dried at 130 ° C. for 2.4 minutes, and then further 130 ° C., 160 ° C., 200 Stepwise heat treatment was performed at 2 ° C., 12 ° C., 230 ° C., 280 ° C., 320 ° C., and 360 ° C. for 2 to 12 minutes to form a polyimide layer on the copper foil.
The results of structural analysis by IR for each polyimide film are shown in FIGS. Also, the copper foil is etched away using ferric chloride aqueous solution to create A to F polyimide film, thermal expansion coefficient (CTE), glass transition temperature (Tg), tensile modulus, 2% weight loss temperature (Td2%), moisture absorption and humidity expansion coefficient (CHE) were determined. In addition, it means that the polyimide films of A to F were obtained from the polyamic acids of A to F, respectively.

Comparative Example 2
The G polyamic acid solution was imidized in the same manner as in Examples 7 to 12 to produce a G polyimide film and evaluated.
Table 2 shows the measurement results of Examples and Comparative Examples.

  The polyimides of Examples 7 to 12 exhibit a low coefficient of thermal expansion required for insulating resin applications such as flexible printed laminates, while maintaining excellent heat resistance, that is, 2% weight loss temperature of 500 ° C. or higher. It showed a low moisture absorption rate and a humidity expansion coefficient. On the other hand, the polyimide of Comparative Example 2 had a high moisture absorption rate and humidity expansion coefficient.

IR spectrum of polyimide film A IR spectrum of polyimide film B IR spectrum of polyimide film C IR spectrum of polyimide film D IR spectrum of polyimide film E IR spectrum of polyimide film F

Claims (5)

An aromatic polyamic acid comprising 10 mol% or more of a structural unit represented by the following general formula (1).

(In the formula, Ar ₁ is a tetravalent organic group having one or more aromatic rings.) An aromatic polyimide comprising 10 mol% or more of a structural unit represented by the following general formula (2).

(In the formula, Ar ₁ is a tetravalent organic group having one or more aromatic rings.) In the general formula (2), at least a part of Ar ₁ is pyromellitic dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, naphthalene-2,3,6,7- Tetracarboxylic dianhydride, naphthalene-1,4,5,8-tetracarboxylic dianhydride, 3,3 ", 4,4" -p-terphenyltetracarboxylic dianhydride, 4,4'- Of at least one aromatic tetracarboxylic acid selected from oxydiphthalic dianhydride, 3,3'4,4'-benzophenonetetracarboxylic dianhydride and bis (2,3-dicarboxyphenyl) sulfone dianhydride The aromatic polyimide according to claim 2, which is a residue.   3. An elastic modulus at 23 ° C. of 4 to 10 GPa, a moisture absorption rate of 0.7 wt% or less, a humidity expansion coefficient of 30 to 50% RH of 9 ppm /% RH or less, and a thermal expansion coefficient of 20 ppm / K or less. Aromatic polyimide described in 1.   3. The method for producing an aromatic polyimide according to claim 2, wherein the aromatic polyamic acid according to claim 1 is imidized.

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