WO2013136807A1 - Polyimide precursor varnish and polyimide resin, and use thereof - Google Patents

Description

Polyimide precursor varnish, polyimide resin, and use thereof

The present invention relates to a polyimide precursor varnish comprising a composition including a polyimide precursor and a solvent. Moreover, it is related with the polyimide resin formed by imidizing the molding obtained from the polyimide precursor varnish. Furthermore, it is related with the use which uses the said polyimide precursor varnish or a polyimide resin.

Wire wiring and cables have a structure in which a metal conductor is coated with an insulating coating material and a conductor portion is protected. Various products have been developed for insulation coatings depending on the application, but engineering plastics such as polyamide, polyamideimide, polyesterimide, and polyimide are used for insulation coating materials such as electric wires and motor windings. Yes. Among these, polyimide exhibits extremely excellent characteristics from the viewpoints of heat resistance, electrical insulation, mechanical strength, and the like, and is therefore used for motor windings that are used in particularly severe environments.

Commercially available polyimides include KAPTON, VESPEL (registered trademark, manufactured by Dupont) consisting of bis (4-aminophenyl) ether and pyromellitic dianhydride, bis (4-aminophenyl) ether and 3,3 Examples include Iupilex (registered trademark, manufactured by Ube Industries) and AURUM (registered trademark, manufactured by Mitsui Chemicals), which are polyimides composed of ', 4,4'-biphenyltetracarboxylic dianhydride.

　式（Ｉ）中、Ｒは炭素数２以上の脂肪族基、環式脂肪族基、単環式芳香族基、縮合多環式芳香族基、芳香族基が直接または架橋員により相互に連結された非縮合多環式芳香族基からなる群より選ばれた４価の基を示し、Ｘは単結合、硫黄原子、スルホン基、カルボニル基、イソプロピリデン基またはヘキサフルオロイソプロピリデン基の２価の基を示す。 In Patent Document 1, a polyimide having a repeating structural unit represented by the following general formula (I) is heated and melted in an extruder at a temperature range of 300 ° C. or higher and 450 ° C. or lower to coat a conductor, cooled and solidified to be insulated. A method of manufacturing an insulated wire for forming a body is described.

In the formula (I), R is an aliphatic group having 2 or more carbon atoms, a cyclic aliphatic group, a monocyclic aromatic group, a condensed polycyclic aromatic group, or an aromatic group directly or via a cross-linking member. Represents a tetravalent group selected from the group consisting of a non-condensed polycyclic aromatic group, wherein X is a single bond, a sulfur atom, a sulfone group, a carbonyl group, an isopropylidene group or a hexafluoroisopropylidene group. The group of is shown.

Patent Document 2 discloses an insulated wire using p-phenylenediamine and 4,4′-diaminodiphenyl ether as diamine and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride as acid dianhydride. Has been.

　一般式（ＩＩ）において、Ｘ_１は下記式（ＩＶ）で表される芳香族エーテル構造を有する４価の芳香族基であり、Ｙ_１は芳香族エーテル構造を有する２価の芳香族基であり、一般式（ＩＩＩ）において、Ｘ_２は４価の脂環式基であり、Ｙ_２は脂環式構造を含む２価の脂環式基であり、一般式（ＩＩ）及び一般式（ＩＩＩ）において、ｍ、ｎは繰り返し数であって、それぞれ正の整数である。

Patent Document 3 discloses a repeating unit represented by the following general formula (II) in order to obtain an insulating paint and an insulated wire that can form an insulating film having heat resistance, high adhesion to a conductor, and low dielectric constant. An insulating paint made of a polyimide resin having a repeating unit represented by the following general formula (III) has been proposed.

In the general formula (II), X ₁ is a tetravalent aromatic group having an aromatic ether structure represented by the following formula (IV), and Y ₁ is a divalent aromatic group having an aromatic ether structure. There, in the general formula (III), X ₂ is a tetravalent alicyclic group, Y ₂ is a divalent alicyclic group containing an alicyclic structure, the general formula (II) and the general formula ( In III), m and n are repeat numbers, each being a positive integer.

JP-A-2-210713 Japanese Patent Laid-Open No. 7-37439 JP 2010-189510 A

The remarkable development of the electronics industry has been supported by the development of various electronic parts and materials used for electronic parts. As described above, excellent materials have been proposed for the insulating materials by vigorous research and development. However, there is a demand for a material having both heat resistance and low water absorption in addition to excellent insulating properties and mechanical strength as a higher performance material in the market. If a material satisfying both heat resistance and low water absorption can be provided, durability in a high temperature environment can be enhanced. In addition, for example, when used as an insulating coating material for an insulated wire, it can be expected to realize a low transmission loss.

In addition, in the above, although the subject in the insulating coating material was described, the same subject may arise regarding various uses including a heat resistant tape, a heat resistant paint, an aerospace adhesive, etc.

The present invention has been made in view of the above background, and the object of the present invention is to provide a material having excellent insulating properties and mechanical strength and satisfying both heat resistance and low water absorption. It is to provide a polyimide precursor varnish, a polyimide resin, and uses thereof.

As a result of extensive studies by the present inventors, it has been found that the problems of the present invention can be solved in the following modes, and the present invention has been completed. That is, the polyimide precursor varnish according to the present invention is a polyimide precursor varnish composed of a composition including a polyimide precursor and a solvent, and the composition is coated and heated at 5 ° C./min and 300 ° C. In the case of a polyimide film having a dried coating thickness of 20 to 60 μm obtained by heat treatment in a nitrogen atmosphere for 1 hour, the glass transition temperature is 290 ° C. or higher, the water absorption is 2.0% or less, and The tensile elongation at break is 55% or more.

（式中、Ｘは単結合、酸素原子、硫黄原子、スルホン基、カルボニル基、メチレン基、イソプロピリデン基またはヘキサフルオロイソプロピリデン基の２価の基を示す）

（式中、Ｙは単結合、酸素原子、硫黄原子、スルホン基、カルボニル基、メチレン基、イソプロピリデン基またはヘキサフルオロイソプロピリデン基の２価の基を示す） In a preferred embodiment of the polyimide precursor varnish disclosed herein, the polyimide precursor is obtained by polycondensation of diamine and acid dianhydride, and the diamine is at least the total amount of the diamine. The diamine component A represented by the chemical formula (1) which is 19 mol% or more and 56 mol% or less with respect to the total amount, and the chemical formula (2) which is 44 mol% or more and 81 mol% or less with respect to the total amount of the diamine. The acid dianhydride component represented by the chemical formula (3) is 60 mol% or more and 100 mol% or less with respect to the total amount of the acid dianhydride. There are some which contain C and acid dianhydride component D represented by chemical formula (4) which is 0 mol% or more and 40 mol% or less with respect to the total amount of the acid dianhydride.

(Wherein X represents a divalent group such as a single bond, oxygen atom, sulfur atom, sulfone group, carbonyl group, methylene group, isopropylidene group or hexafluoroisopropylidene group)

(In the formula, Y represents a divalent group of a single bond, an oxygen atom, a sulfur atom, a sulfone group, a carbonyl group, a methylene group, an isopropylidene group or a hexafluoroisopropylidene group)

In a preferred embodiment of the polyimide precursor varnish disclosed herein, the polyimide precursor has a total of 47. diamine component A and diamine component B with respect to the total of diamine and acid dianhydride. 5 to 52.5 mol%, copolymerized so that the total of the acid dianhydride component C and the acid dianhydride component D satisfies 47.5 to 52.5 mol%.

Further, in a preferred embodiment of the polyimide precursor varnish disclosed herein, there is one in which the diamine component B is 4,4′-bis (3-aminophenoxy) biphenyl described by the chemical formula (5).

Further, in a preferred embodiment of the polyimide precursor varnish disclosed herein, there is one in which the diamine component A is 4,4′-diaminodiphenyl ether described by the chemical formula (6).

In one preferred embodiment of the polyimide precursor varnish disclosed herein, the acid dianhydride component D is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride described by the chemical formula (7). There are things that are things.

The polyimide resin according to the present invention is formed by imidizing a molded product obtained from the polyimide precursor varnish of the above embodiment.
Moreover, in the preferable one aspect | mode of the polyimide resin disclosed here, there exists an aspect used as an insulation coating material which coat | covers a conductor.

An electronic component according to the present invention is an electronic component comprising a conductor and an insulating coating material covering the conductor, wherein at least a part of the insulating coating material is obtained from the polyimide precursor varnish of the above aspect. A polyimide resin formed by imidizing the molded product. A suitable example of the electronic component is an insulated wire.

The heat-resistant tape according to the present invention includes a support base material and a bonding layer formed on the support base material, and the support base material is formed by immobilizing a molded product obtained from the polyimide precursor varnish of the above aspect. It contains a polyimide resin formed as a component.

The heat resistant paint according to the present invention includes the polyimide precursor varnish of the above aspect.

The aerospace adhesive according to the present invention includes the polyimide precursor varnish of the above aspect or a gel film formed from the polyimide precursor varnish.

According to the present invention, it is possible to provide a polyimide precursor varnish, a polyimide resin, and uses thereof that have excellent insulating properties and mechanical strength, and that can provide a material that has both heat resistance and low water absorption. There is an excellent effect of being able to. Moreover, according to this invention, there exists an outstanding effect that the raw material excellent in the low water absorption can be provided.

The typical sectional view showing an example of the insulated wire concerning this embodiment. The typical sectional view showing an example of the insulated wire concerning a modification. The typical sectional view showing an example of the heat-resistant tape concerning this embodiment.

Hereinafter, an example of an embodiment to which the present invention is applied will be described. Needless to say, other embodiments are also included in the scope of the present invention as long as they meet the spirit of the present invention. Further, the sizes and ratios of the members in the following drawings are for convenience of explanation, and do not necessarily match the actual ones. In this specification, the description “any number A to any number B” means a range larger than the numbers A and A but smaller than the numbers B and B.

[Polyimide precursor varnish, polyimide resin] The polyimide precursor varnish according to the present invention is composed of a composition including a polyimide precursor and a solvent. More specifically, the coating film thickness after drying obtained by coating a polyimide precursor varnish as a composition and heat-treating at 5 ° C./min and 300 ° C. for 1 hour in a nitrogen atmosphere. In a polyimide film having a range of 20 μm or more and 60 μm or less (hereinafter simply referred to as “polyimide film”), (i) a glass transition temperature is 290 ° C. or more, (ii) a water absorption is 2.0% or less, and (iii) ) All conditions satisfying a tensile elongation at break of 55% or more.
The polyimide resin of the present invention is formed by imidizing a molded product obtained from the polyimide precursor varnish of the present invention. Here, the molded product is a coating film, a film, a sheet, a molded product, a gel film, or the like.

In order to make the coating film thickness after drying the polyimide film 20 to 60 μm, for example, the polyimide precursor varnish may be coated to 300 to 400 μm. Although the production method of the said polyimide film is not specifically limited, The following method is mentioned as an example. That is, the polyimide precursor varnish is applied on a glass plate with a 300-400 μm gap applicator using a desktop coating machine. Then, immediately using an explosion-proof dryer, the temperature is raised from room temperature to 5 ° C./min in a nitrogen atmosphere as described above, and held at 300 ° C. for 1 hour. Then, after sufficiently cooling by natural cooling, the polyimide film is peeled from the glass plate by being immersed in warm water for 24 hours. Then, by sufficiently drying, the coating film thickness after drying is made to be 20 to 60 μm.

The polyimide precursor varnish according to the present invention only needs to satisfy the above characteristics (i) to (iii) when a polyimide film having the above film thickness is produced. Use of the polyimide precursor varnish of the present invention The film thickness of the embodiment is not specified. That is, the polyimide precursor varnish of the present invention can be used to obtain films, sheets, and molded articles having various film thicknesses.

As a result of extensive studies by the present inventors, when the polyimide film is produced, the use of a polyimide precursor varnish that satisfies all of the above characteristics (i) to (iii) makes it possible to obtain excellent insulation characteristics and mechanical properties. It has been found that a material having strength and capable of achieving both heat resistance and low water absorption can be provided. Details will be described below.

From the viewpoint of providing a more excellent material in the polyimide film, the glass transition temperature of (i) is more preferably 295 ° C. or higher, and further preferably 300 ° C. or higher. Further, the water absorption rate of (ii) is more preferably 1.9% or less, and further preferably 1.8% or less. Further, the tensile elongation at break of (iii) is more preferably 70% or more, and particularly preferably 100% or more. From the viewpoint of improving the partial discharge voltage resistance as an insulator, the dielectric constant of the polyimide resin at a measurement frequency of 1 Hz is preferably 3.6 or less, more preferably 3.5 or less. More preferably, it is 4 or less.

In the present specification, the glass transition temperature is a value measured by the following method. That is, the temperature dispersion measurement of the solid viscoelasticity of the polyimide film is performed in a tensile mode using RSA-II manufactured by TA instruments under the condition of a measurement frequency of 1 Hz, and the storage elastic modulus E ′ and the loss elastic modulus E ″ are measured. Then, a value derived from the peak value of the obtained loss tangent tan δ = E ″ / E ′ is defined as “glass transition temperature”.

Moreover, the water absorption rate of this specification says the value measured with the following method. That is, the polyimide film is cut into a size of 50 mm × 50 mm, dried at 150 ° C. for 5 minutes, and then immediately measured for mass. Then, it is immersed in ion exchange water at 23 ° C. for 24 hours. After immersion, the moisture attached to the surface of the sample taken out from the water tank is sufficiently blown off using an air gun or the like, the mass is measured, and the value calculated from the following formula (1) is taken as the water absorption rate.
<Equation 1>
Water absorption rate = {(Sample weight after immersion)-(Sample weight before immersion)} ÷ (Sample weight before immersion)
..Formula (1)

Further, the tensile elongation at break means a value measured by the following method. That is, the polyimide film was cut into a size of 140 mm in length × 10 mm in width, the actual measurement length was 100 mm (of which 20 mm at both ends was the pulling region), and the room temperature (23 The strip-shaped film sample was pulled at a speed of 50 mm / min. The value calculated from (length of polyimide film at break) / (original length of polyimide film) at this time is taken as the tensile break elongation.

The polyimide precursor which is a component of the polyimide precursor varnish of the present invention can be obtained by polycondensation of diamine and acid dianhydride. Hereinafter, preferred embodiments of suitable polyimide precursors for satisfying the above characteristics will be described.

　化学式（２）中、Ｘは単結合、酸素原子、硫黄原子、スルホン基、カルボニル基、メチレン基、イソプロピリデン基またはヘキサフルオロイソプロピリデン基の２価の基を示す。 The polyimide precursor of the present invention is not limited as long as it satisfies the above characteristics (i) to (iii), but preferred monomers include the following aspects. That is, the diamine is at least 19 mol% and not more than 56 mol% with respect to the total amount of the diamine, and the diamine component A represented by the chemical formula (1) and at least 44 mol% and 81 mol with respect to the total amount of the diamine. There exists an aspect which uses the diamine component B shown by Chemical formula (2) which is% or less as a structural component.

In the chemical formula (2), X represents a single bond, an oxygen atom, a sulfur atom, a sulfone group, a carbonyl group, a methylene group, an isopropylidene group, or a hexafluoroisopropylidene group.

　化学式（４）中、Ｙは単結合、酸素原子、硫黄原子、スルホン基、カルボニル基、メチレン基、イソプロピリデン基またはヘキサフルオロイソプロピリデン基の２価の基を示す。 The acid dianhydride is an acid dianhydride component C that is pyromellitic dianhydride represented by the chemical formula (3) that is at least 60 mol% and not more than 100 mol% with respect to the total amount of the acid dianhydride, And there exists an aspect which uses the acid dianhydride component D shown by Chemical formula (4) which is 0 mol% or more and 40 mol% or less with respect to the total amount of the said acid dianhydride as a structural component. The lower limit value of pyromellitic dianhydride represented by the chemical formula (3) is more preferably 70 mol% or more, and further preferably 80 mol% or more. Further, the upper limit value of the acid dianhydride component D represented by the chemical formula (4) is more preferably 30 mol% or less, and further preferably 20 mol% or less.

In chemical formula (4), Y represents a divalent group such as a single bond, oxygen atom, sulfur atom, sulfone group, carbonyl group, methylene group, isopropylidene group or hexafluoroisopropylidene group.

In the above chemical formulas (1), (2), and (4), a single or a plurality of types of compounds can be used independently when synthesizing a polyimide precursor.

Preferred examples of the diamine component B of the chemical formula (2) include bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy). ) Phenyl] ketone, 4,4′-bis (3-aminophenoxy) biphenyl, 4,4′-bis (4-aminophenoxy) biphenyl, 2,2-bis [4- (3-aminophenoxy) phenyl] propane 2,2-bis [4- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane and the like.

As a particularly preferred example of the diamine component B, 4,4′-bis (3-aminophenoxy) biphenyl described by the chemical formula (5) can be given.

Preferable examples of the diamine component A of the chemical formula (1) include 4,4′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether and the like. From the viewpoint of improving crystallinity, 4,4′-diaminodiphenyl ether represented by the chemical formula (6) is particularly preferable.

The diamine is preferably such that the diamine component A is 19 to 56 mol% with respect to the total amount of diamine and the diamine component B is 44 to 81 mol% with respect to the total amount of diamine. By setting it as this range, it is possible to achieve both low water absorption and high Tg more effectively. The lower limit of the diamine component A with respect to the total amount of diamine is more preferably 20 mol% or more, further preferably 24 mol% or more, particularly preferably 30 mol% or more, and most preferably 39 mol% or more. Further, the upper limit value of the diamine component A relative to the total amount of diamine is more preferably 51 mol% or less, and further preferably 50 mol% or less. The lower limit value of the diamine component B relative to the total amount of diamine is more preferably 49 mol% or more, and the upper limit value is more preferably 80 mol% or less, still more preferably 76 mol% or less, particularly preferably 70 mol% or less, and 61 mol%. The following are most preferred.

As the diamine in the present embodiment, a diamine other than the above chemical formulas (1) and (2) may be used as long as the above-mentioned polyimide film satisfies the characteristics (i) to (iii). From the viewpoint of heat resistance, the other diamine is preferably an aromatic diamine.

Other aromatic diamines include, for example, p-phenylenediamine, m-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, 4,4′-diaminobiphenyl, 3,3′-diaminobiphenyl, 4,4 '-Diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 1,1-bis (4-aminophenyl) ethane, 1,1-bis (3-aminophenyl) ethane, 2,2-bis (4-aminophenyl) Propane, 2,2-bis (3-aminophenyl) propane, 2,2-bis (4-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 2,2-bis- ( 3-aminophenyl) -1,1,1,3,3,3-hexafluoropropane, 3,3′-diaminodiphenyl sulfide, 4,4′-diaminodiphe Sulfides, 3,3′-diaminodiphenylsulfone, 3,3′-diaminobenzophenone, 4,4′-diaminobenzophenone, 1,3-bis (3-aminophenoxy) benzene, 1,3-bis (4-aminophenoxy) ) Benzene, 2,2′-bis (4- (4-aminophenoxy) phenyl) propane, 2,2′-dimethyl-4,4′-diaminobiphenyl, bisaminophenylfluorene, bistoluidine fluorene, 2,7- Diaminofluorene, 2,2'-bis (trifluoromethyl) -1,1'-biphenyl-4,4'-diamine, 4,4'-methylenedianiline, 4,4 '-(m-phenylenediisopropylidene ) Dianiline and the like.

Preferred examples of the acid dianhydride component D represented by the chemical formula (4) include 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,2 ′, 3,3′-biphenyltetra Carboxylic dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride, 2,2 ′, 3,3′-benzophenone tetracarboxylic dianhydride, 2,2-bis (3 4-dicarboxyphenyl) propane dianhydride, 2,2-bis (2,3-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (2,3 -Dicarboxyphenyl) ether dianhydride, bis (3,4-dicarboxyphenyl) sulfone dianhydride, bis (2,3-dicarboxyphenyl) sulfone dianhydride, 2,2-bis (3,4- Dicarboxyfe 1) 1,1,1,3,3,3-hexafluoropropane dianhydride, 2,2-bis (3,4-dicarboxyphenyl) 1,1,1,3,3,3-hexachloropropane Anhydride, 1,1-bis (2,3-dicarboxyphenyl) ethane dianhydride, bis (2,3-dicarboxyphenyl) methane dianhydride, bis (3,4-dicarboxyphenyl) methane dianhydride Compounds, 4,4 ′-(p-phenyldioxy) diphthalic dianhydride, 4,4 ′-(m-phenylenedioxy) diphthalic dianhydride, and the like.

Among these, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3,3 ′, 4,4 ′ -More preferred are diphenyl ether tetracarboxylic dianhydride and p-phenylenedioxydi (4-phthalic acid) dianhydride.
Particularly preferred is 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride described by the chemical formula (7).

As the acid dianhydride, the acid dianhydride component C may be used alone, or in addition to the acid dianhydride component C, the acid dianhydride component D may be added. As the acid dianhydride component D, one type of compound may be used, or two or more types may be mixed and used. As the acid dianhydride in the present embodiment, an acid dianhydride other than the chemical formulas (3) and (4) can be used as long as the characteristics (i) to (iii) are satisfied. From the viewpoint of heat resistance, the other acid dianhydride is preferably an aromatic acid dianhydride.

As preferable examples of other aromatic dianhydrides, 1,2,3,4-benzenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,4 5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6, 7-anthracene tetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, and the like.

The number average molecular weight of the polyimide precursor according to this embodiment is not particularly limited, but can be, for example, in the range of 5,000 to 1,000,000. A preferred range is 5,000 to 50,000. The number average molecular weight of the polyimide precursor can be measured by gel permeation chromatography (GPC).

Next, a method for producing a polyimide precursor varnish will be described. First, the above-mentioned specific diamine and specific tetracarboxylic dianhydride are reacted to obtain a polyamic acid. The ratio of the polyimide precursor acid dianhydride and diamine during synthesis is not particularly limited, but the total of diamine component A and diamine component B is 47.5 to 52.5 mol with respect to the total of diamine and acid dianhydride. %, And the acid dianhydride component C and the acid dianhydride component D are preferably copolymerized in a range satisfying 47.5 to 52.5 mol%.

Polymerization can be performed in a solid phase system, but is preferably performed in a liquid phase system. In the liquid phase system, the polymerization concentration is, for example, about 20 to 30% by mass. The reaction solvent is not particularly limited, but preferably has a boiling point of 100 ° C. or higher. In general, a solvent used for polymerization of a polyimide precursor can be suitably used. For example, it dissolves at least one reactant, preferably both acid dianhydrides and diamines. Specific examples include N, N-dimethylformamide, N, N-dimethylacetamide, cresol, dimethyl sulfoxide, N-methyl-2-pyrrolidone, tetramethylurea and the like. These solvents can be used alone or in combination with other solvents such as benzonitrile, dioxane, xylene or toluene.

The production of the polyimide precursor can be performed without using a catalyst, but a catalyst may be used as appropriate. The catalyst is not particularly limited as long as it does not depart from the spirit of the present invention. The amount of the catalyst used may be appropriately adjusted in consideration of the properties of the catalyst itself such as the volatility of the catalyst and the acid strength, and the reaction conditions.

In the liquid phase reaction step, the order and method of charging the raw materials, the solvent, and other catalysts added as necessary are not particularly limited. The reaction temperature is not particularly limited as long as the necessary number average molecular weight (Mn) is obtained, but is usually 20 ° C. or higher and 100 ° C. or lower when polyamic acid is polymerized as a polyimide precursor. The reaction time is not limited to a range that is sufficient to obtain the required degree of polymerization. Further, the reaction is preferably performed in an inert gas atmosphere such as nitrogen. The solid content concentration in the reaction system (in the reactor) is not particularly limited, but is usually 5% by mass to 50% by mass.

Although the reaction apparatus is not particularly limited, Super Blend (Sumitomo Heavy Industries, Ltd.), Aiko Chemical Mixer (Aikosha Seisakusho), Planetary Mixer (Inoue Seisakusho), Trimix (Inoue Seisakusho), etc. These kneaders can be mentioned.

The concentration of the resin solid content in the polyimide precursor varnish is preferably 5 to 50% by mass, more preferably 10 to 30% by mass, from the viewpoint of improving the coatability. The solvent is not particularly limited, but is preferably a polar solvent. Examples of polar solvents include N, N-dimethylformamide, N, N-dimethylacetamide, N, N-diethylformamide, N, N-diethylacetamide, N, N-dimethylmethoxyacetamide, dimethyl sulfoxide, hexamethyl phosphor In addition to amide, N-methyl-2-pyrrolidone, dimethylsulfone, etc., a mixed solvent of two or more of these, or benzene, toluene, xylene, benzonitrile, dioxane, cyclohexane, 1, A mixed solvent with 3,5-trimethylbenzene, 1,2,4-trimethylbenzene or the like is included.

Any additive may be added to the polyimide precursor varnish according to the present invention without departing from the spirit of the present invention. For example, an adhesion assistant, an adhesive, an antioxidant, an ultraviolet absorber, a colorant, or the like may be added. Further, a surface modifier such as a silane coupling agent may be added. Examples of preferable additives include epoxy, bismaleimide, and nadiimide. From the viewpoint of heat resistance and reactivity, it is preferable to add bismaleimide having a molecular weight of 600 or less. The polyimide precursor according to the present invention may be a single type or a mixture of a plurality of types. Furthermore, the polyimide precursor varnish of the present invention may be mixed with a polymer different from the polyimide precursor according to the present invention without departing from the spirit of the present invention. That is, in the polyimide resin obtained from the polyimide precursor varnish, other polymers may be included without departing from the spirit of the present invention. Moreover, in the polyimide precursor varnish, what was partially imidized may be contained.

Conventional polyimide resins generally have a water absorption rate exceeding 2.0% due to imide groups. For this reason, for example, when a polyimide resin is applied as an insulating coating material for a conductor of an insulated wire, there is a problem in that transmission loss increases due to the insulating coating material. In addition, the conventional polyimide resin has a problem in that poor insulation is likely to occur due to water absorption under high humidity heat.

By adopting the polyimide structure as in Patent Document 1, it is possible to relatively reduce the imide group density and improve the water absorption rate. However, since the glass transition temperature is lowered due to this, there is a problem in terms of heat resistance. Thus, the polyimide resin has a trade-off relationship between low water absorption and heat resistance, and it has been difficult to satisfy both low water absorption and heat resistance. In addition, when molding by melt extrusion molding method as in Patent Document 1, molding at a high temperature of 400 ° C. or higher is generally necessary, and since it is close to the thermal decomposition temperature of the resin, it is necessary to precisely control the molding conditions. was there.

According to the polyimide precursor varnish of the present invention, the above-mentioned polyimide film has a glass transition temperature of 290 ° C. or higher, a water absorption rate of 2.0% or less, and a tensile breaking elongation of 55% or more. It is possible to provide a polyimide resin excellent in balance and having a high glass transition temperature and a high mechanical strength. More specifically, by setting the glass transition temperature to 290 ° C. or higher, excellent reliability and durability can be realized even in a high temperature environment. For example, it can be used for a long time even in an environment of about 250 ° C. Further, by setting the water absorption rate to 2.0% or less, a low transmission loss can be realized when used as an insulating coating material for covering a conductor. In addition, it is possible to improve the problem that insulation failure tends to occur under high humidity. Furthermore, when the tensile elongation at break is 55% or more, excellent mechanical strength can be realized, and excellent reliability and durability can be realized. Further, by setting the tensile elongation at break to 55% or more, the flexibility is excellent. Moreover, according to the method of applying the polyimide precursor varnish of the present invention, it has an excellent merit that it can be dried by heating at 400 ° C. or lower and it is easy to form a thin film.

By using the diamine having the above-mentioned specific structure as the polyimide precursor, and using the acid dianhydride having the above-mentioned specific structure, the above-mentioned excellent balance between low water absorption, high glass transition temperature, and high mechanical strength. It is possible to easily provide a polyimide resin having the effect described above. By introducing pyromellitic dianhydride of chemical formula (3) or pyromellitic dianhydride and chemical formula (4) as acid dianhydride and using diamines of chemical formulas (1) and (2) When the polyimide resin is used, the imide group density can be lowered and the crystallinity can be improved while realizing the rigidity. As a result, we consider that we succeeded in balancing low water absorption, high glass transition temperature and high mechanical strength. In addition, the polyimide resin obtained has an excellent merit that low dielectric constant can be realized.

In addition, 4,4′-bis (3-aminophenoxy) biphenyl (hereinafter referred to as mBP) and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter referred to as s-BPDA) are included in the polyimide skeleton. Introducing a structure mainly composed of biphenyl structure such as lowering the density of imide groups and improving crystallinity more effectively, and by introducing 4,4′-diaminodiphenyl ether and pyromellitic dianhydride Stiffening can be realized. Therefore, it is possible to more effectively balance the low water absorption, the high glass transition temperature, and the high mechanical strength. As a result, for example, when a wire covering material is used, a reduction in transmission loss can be achieved more effectively.

Also, polyimide resin has excellent chemical resistance. Therefore, there is an excellent merit that it can be used even in severe conditions such as high temperature and high humidity and in applications where chemical resistance is required. According to the polyimide precursor varnish of the present invention, it is possible to provide a material having excellent insulating properties and mechanical strength, and having both heat resistance and low water absorption, so various electronic parts such as insulated wires, heat resistant tape, heat resistance It can be suitably used for a wide range of applications including paints and aerospace adhesives. Hereinafter, an example of the embodiment formed using the polyimide precursor varnish of the present invention will be described.

[Insulated Wire] FIG. 1A is a schematic cross-sectional view showing an example of an insulated wire according to the present invention. The insulated wire 1 has a conductor 10 and an insulating coating layer 20 formed of an insulating coating material. The conductor 10 is not particularly limited as long as it can function as an electric wire. For example, the conductor 10 is made of a conductive material such as oxygen-free copper, copper, aluminum, an aluminum alloy, or a combination thereof. The insulating coating layer 20 covers the conductor 10 and is made of a polyimide resin formed using a polyimide precursor varnish. Between the conductor 10 and the insulating coating layer 20, an adhesion layer that improves the bonding may be provided. In the example of FIG. 1A, the example in which the insulating coating layer 20 is formed from one layer of polyimide resin is shown. However, as shown in FIG. 1B, the first insulating coating layer 21, the second insulating coating layer 22, and the like 2 The insulating coating layer 20 may be a laminated structure of layers, or may be a laminated structure of three or more layers. When a plurality of layers are laminated, a plurality of polyimide resins formed using the polyimide precursor varnish according to the present invention may be laminated, or a laminate of another insulating layer and the polyimide resin of the present invention may be used. . The other insulating layer is not particularly limited, but can be appropriately designed according to needs, such as a material that improves the adhesion to the conductor 10 or a highly flexible material.

The thickness of the insulating coating layer 20 can be arbitrarily set according to the application and is not particularly limited, but can be set to about 1 to 100 μm, for example. A more preferable lower limit value of the insulating coating layer 20 is 10 μm or more, and a more preferable range is 20 μm or more. The insulating coating layer 20 is obtained by applying a polyimide precursor varnish to the conductor 10, drying it, and baking it. Although the coating method is not particularly limited, a method of directly or indirectly coating the outer periphery of the conductor 10 can be exemplified. The polyimide precursor is converted into polyimide by baking. In the case where a plurality of insulating coating layers are laminated, it can be formed by repeating the coating and baking process. When an insulating coating layer other than the polyimide resin layer is laminated, a known forming method can be used as appropriate.

The baking step is not particularly limited, but is preferably performed in an inert gas, and can be performed, for example, in a nitrogen atmosphere. The heating condition is not particularly limited as long as it can be converted from the polyimide precursor to the polyimide, and examples include heating at about 200 to 400 ° C. for 1 minute to 10 hours. In addition, although the conductor 10 and the insulating coating layer 20 described above have examples in which the cross section has a round cross section, the cross section is not particularly limited, and may be independently a rectangular shape, an elliptical shape, or the like. .

According to the insulated wire of the present invention, since the polyimide resin obtained from the polyimide precursor varnish according to the present invention is used for at least one layer of the insulating coating layer 20, the mechanical strength is excellent. Therefore, the internal conductor 10 can be appropriately protected even when a strong external force is applied. In addition, since the polyimide resin according to the present invention is excellent in low water absorption, when used as the insulated wire 1, low transmission loss can be realized. Furthermore, since the polyimide resin according to the present invention is excellent in chemical resistance and heat resistance, it can be suitably used even under severe conditions such as high temperature and high humidity.

[Heat-resistant tape] Fig. 2 is a schematic cross-sectional view showing an example of the heat-resistant tape of the present invention. The heat-resistant tape 2 includes a support base 30 and a bonding layer 31. Between the support base material 30 and the joining layer 31, you may provide the intermediate | middle layer etc. which strengthen these joining. As the heat-resistant tape 2, for example, a support base 30 and a bonding layer 31 that have heat resistance are used in order to ensure heat resistance that can be used even in a high temperature region around 200 ° C.

The support substrate 30 includes a polyimide resin layer formed from at least the polyimide precursor varnish of the present invention. The support substrate 30 may be composed of a single layer or a plurality of polyimide resin layers, or may be a laminate of a layer made of another material and a polyimide resin layer. Other materials are not limited as long as they do not depart from the spirit of the present invention, and examples thereof include metal foils such as aluminum foil, metal layers, plastic films, and the like. What is excellent in bondability with the polyimide resin layer formed from the polyimide precursor varnish of this invention, and excellent in heat resistance is preferable.

The bonding layer 31 is not particularly limited as long as it can be bonded to the adherend and does not depart from the gist of the present invention, but an adhesive layer is usually used. Preferable examples of the bonding layer 31 include a silicone pressure sensitive adhesive, a rubber pressure sensitive adhesive, and an acrylic pressure sensitive adhesive. From the viewpoint of increasing the heat resistance of the bonding layer 31, it is preferably thermosetting.

The thickness and size of the heat-resistant tape 2 can be appropriately designed according to various uses. For example, the thickness of the support base 30 is preferably about 2 to 100 μm. The lower limit value of the support substrate 30 is more preferably 5 μm or more, and further preferably 10 μm or more. Further, the upper limit value of the support substrate 30 is more preferably 50 μm or less, and further preferably 30 μm or less. The thickness of the bonding layer 31 can be about 3 to 100 μm, for example. The adhesive force can be adjusted by adjusting the thicknesses of the support base 30 and the bonding layer 31. A heat-resistant tape excellent in followability and a high-rigidity heat-resistant tape can be provided by appropriately selecting the thickness, the material of the bonding layer, and the laminated form according to the required use.

The heat-resistant tape 2 can be manufactured by various methods, and the following methods can be exemplified. That is, a gel film is obtained by continuously extruding or coating a polyimide precursor varnish in a film form on a rotating support. Next, the gel film is peeled from the support, and imidized by stretching, drying, and heat treatment to obtain the support substrate 30. Thereafter, the bonding layer 31 is formed thereon by a conventionally known coating method. The coating method is not particularly limited, and examples thereof include a roll coater method, a reverse roll coater method, a gravure roll method, a bar coat method, a comma coater method, and a die coater method. The drying conditions of the applied pressure-sensitive adhesive may be appropriately adjusted depending on the pressure-sensitive adhesive to be used, but in general, it is dried for 10 seconds to 10 minutes in a temperature range of 80 to 200 ° C.

The gel film referred to in the present invention is a film containing a polyimide precursor and / or a polyimide precursor mixed with a partially imidized polyimide resin, and a solvent. For example, the gel film has a film thickness of about 1 to 100 μm and a solvent content of about 1 to 70% by mass.

The heat-resistant tape 2 is not limited to the example of FIG. 2 and can take various forms. For example, it is good also as a double-sided tape which provided the joining layer on both surfaces of the support base material 30. FIG. Moreover, it is good also as a structure which laminates | stacks a peeling film on the upper layer of the joining layer 31, and peels a peeling film at the time of use. Moreover, it can also be set as a roll-shaped heat-resistant tape. The size of the heat-resistant tape 2 of the present invention is not particularly limited, and includes a sheet-like one in addition to a so-called tape-like form having a strip shape. Further, the gel film itself obtained from the polyimide precursor varnish can be used as the heat-resistant tape 2 without providing the bonding layer 31.

According to the heat-resistant tape of the present invention, since the polyimide resin obtained from the polyimide precursor varnish of the present invention is used, it has excellent insulating properties and mechanical strength, and further has both heat resistance and low water absorption. In addition, it has excellent chemical resistance and weather resistance. Moreover, since it is excellent also in flexibility, it can be applied to adherends of various shapes. Therefore, for example, it is suitable as a masking tape used for heat equipment such as heat rolls and heaters, electrical insulation of members used under heating and pressurizing conditions, and a protective tape for printed circuit boards in the field of semiconductor manufacturing processes.

[Heat-resistant paint] An example in which the polyimide precursor varnish of the present invention is used as a heat-resistant paint will be described. The heat-resistant paint of the present invention can contain a pigment as necessary. The type of pigment is not particularly limited as long as it does not depart from the gist of the present invention, but as an example, carbon black, zinc phosphate, aluminum phosphate, calcium phosphate, magnesium phosphate, zinc molybdate, calcium molybdate, silica sand, calcium carbonate , Talc, clay, kaolin, precipitated barium sulfate and the like. Anticorrosive pigments having heat resistance and corrosion resistance are preferred. In addition, other additives can be arbitrarily added to the heat-resistant paint of the present invention without departing from the spirit of the present invention. Examples include reinforcing materials, curing agents, asphalt emulsions, film-forming aids, antifoaming agents, dispersants, thickeners, plasticizers, antiseptics, antibacterial agents, rust inhibitors, and colorants.

Resin other than the polyimide precursor may be added to the heat resistant paint within a range not departing from the gist of the present invention. The resin other than the polyimide precursor may be either a thermoplastic resin or a thermosetting resin, but is preferably a thermosetting resin from the viewpoint of heat resistance.

The solid content concentration of the heat-resistant paint of the present invention is not particularly limited as long as a coating film can be formed, but is preferably about 10 to 70% by mass. If it is less than 10% by mass, the thick film coatability is lowered, and if it exceeds 70% by mass, problems are likely to occur in the workability at the time of blending, storage stability and the like.

Examples of the heat-resistant paint coating method of the present invention include, for example, a method in which the above-described polyimide precursor varnish is applied to a surface to be coated, and heat treatment is performed under conditions that allow conversion from the polyimide precursor to polyimide. The surface to be coated can be applied to various materials such as metal materials, ceramic materials, and plastic materials. In order to improve the adhesion to the surface to be coated, the surface to be coated may be subjected in advance to a surface treatment such as plasma treatment or blast treatment, or an undercoat layer may be formed.

Although the heat-resistant paint film is obtained by a method of imidization by heat treatment, a known method can be used without limitation as a coating method. For example, the method of forming a coating film by the coating method, the dipping method, the spray method, the brush coating method etc. can be illustrated. The heat treatment condition is not particularly limited as long as it can be converted from a polyimide precursor to a polyimide. For example, it can be obtained by heating at about 200 to 400 ° C. for 1 minute to 10 hours. You may carry out in air | atmosphere or you may carry out by nitrogen atmosphere formation etc. Through these steps, a heat-resistant film is obtained. What is necessary is just to design a film thickness suitably according to a use.

According to the heat-resistant coating material of the present invention, since the polyimide resin obtained from the polyimide precursor varnish of the present invention is contained as a main component, it has excellent insulating properties and mechanical strength, and has both heat resistance and low water absorption. Can provide. In addition, it has excellent chemical resistance and weather resistance. Moreover, since it is excellent also in flexibility, it can be applied as a heat-resistant film on a surface to be coated having a wide variety of shapes. Specifically, it is suitable for electrical / electronic equipment, machines, automobiles, aerospace equipment, general industrial equipment, and the like. It is also suitable for applications exposed to high temperature environments.

[Aerospace Adhesive] An aerospace adhesive containing the polyimide precursor varnish of the present invention or the polyimide resin of the present invention will be described. The aerospace adhesive of the present invention may be composed only of the polyimide precursor varnish of the present invention, or may be mixed when other adhesive components such as a two-component type are used. Moreover, it may consist of a polyimide resin film obtained by imidizing a coating film of a polyimide precursor varnish.

One aspect of the aerospace adhesive includes a polyimide precursor varnish. As the resin, a resin other than the polyimide precursor may be added without departing from the gist of the present invention. The resin other than the polyimide precursor may be either a thermoplastic resin or a thermosetting resin, but is preferably at least partially compatible with the polyimide precursor, and is preferably a thermosetting resin from the viewpoint of heat resistance. Suitable resins include epoxy resins, bismaleimide resins, acrylic resins, benzoxazole resins and the like.

The amount of the thermosetting resin is preferably 1 to 200 parts by mass, more preferably 5 to 100 parts by mass with respect to 100 parts by mass of the polyimide resin. It is desirable in that the film is suitable and the film formability is improved.

Among these thermosetting resins, those with various structures are commercially available, the industrial application range is wide, appropriate curing can be realized, and the crosslinking density can be controlled by the blending ratio, Epoxy resins are preferred. The epoxy resin is not particularly limited as long as it contains at least two epoxy groups in the molecule. For example, phenol glycidyl ether type epoxy resins include bisphenol A, bisphenol AD, bisphenol S, bisphenol F or a condensate of halogenated bisphenol A and epichlorohydrin, glycidyl ether of phenol novolac resin, glycidyl ether of cresol novolac resin, bisphenol A novolak Examples thereof include glycidyl ether of resin, glycidyl ether of dicyclopentadiene-modified phenol novolac resin, and biphenyl type epoxy resin.

Further, it may contain a curing agent as required, and examples thereof include a phenolic curing agent, an amine curing agent, an acid anhydride curing agent, and imidazoles. Furthermore, you may mix | blend the inorganic substance filler. The filler is blended for the purpose of imparting low thermal expansion, low hygroscopicity, high elasticity, high thermal conductivity, etc. to the adhesive, and also contributes to improving the strength of the film adhesive. Examples of the inorganic filler include inorganic insulators such as silica, alumina, silicon nitride, aluminum nitride, boron nitride, titania, glass, iron oxide, and ceramic. These can be used individually or in mixture of 2 or more types. Furthermore, a coupling agent such as a silane coupling agent or a titanium-based coupling agent may be appropriately added to the adhesive as necessary, as long as the object of the present invention is not impaired. A coupling agent contributes to the improvement of the adhesive strength in the adhesion interface with a to-be-adhered body or a filler.

The amount of solvent in the aerospace adhesive of the present invention is not particularly limited, but is usually adjusted so that the viscosity of the varnish has fluidity. When the amount of the polyimide precursor component usually contained in the varnish is in the range of 1 to 40% by mass, preferably 5 to 35% by mass, more preferably 10 to 30% by mass, the fluidity, workability, film formability, coating It is desirable in terms of workability. Further, the viscosity of the varnish is not particularly limited, but is appropriately selected within a range that is easy to handle, and may further contain a viscosity adjusting agent or the like as necessary.

The coated surface of the aerospace adhesive of the present invention is not particularly limited, and examples thereof include metal materials, ceramic materials, plastic materials, and the like. In order to improve the adhesion to the surface to be coated, the surface to be coated may be subjected in advance to a surface treatment such as plasma treatment or blast treatment, or an undercoat layer may be formed. The aerospace adhesive may be applied as it is or may be formed on a base film. A coating film forming method, a heat treatment method, and the like are not particularly limited. For example, the example demonstrated by the coating method of a heat-resistant paint can be given.

Also, another embodiment of the aerospace adhesive of the present invention is a film. When a film-like adhesive is used, the above-described method using a gel film is preferable. That is, a gel film is obtained by continuously extruding or coating a polyimide precursor varnish in a film form on a rotating support, and the gel film is peeled from the support, and is manufactured by stretching, drying, and heat treatment. The method is preferred. Also, a method of obtaining a coating film on a glass substrate or a highly releasable polyimide film and peeling off after heat treatment, or peeling off a gel film applied on a release-treated PET film, Examples of the method include manufacturing by stretching, drying, and heat treatment.

The thickness of the film-like adhesive layer may be, for example, about 1 to 200 μm, although it depends on the application. When a film adhesive is used, it can be sandwiched between objects to be bonded and thermocompression bonded. The temperature at the time of pressure bonding is preferably higher than the glass transition temperature of the resin composition, and is usually 300 to 450 ° C., preferably 350 to 400 ° C. Within such a range, the polyimide composition can be sufficiently bonded without thermal decomposition.

According to the aerospace adhesive of the present invention, the polyimide resin obtained from the polyimide precursor varnish of the present invention is contained as a main component, so that it has excellent insulating properties and mechanical strength, and has both heat resistance and low water absorption. To do. In addition, it has excellent chemical resistance and weather resistance. Moreover, since it is excellent also in flexibility, it is suitable as an aerospace adhesive used under severe high temperature environment and high humidity environment.

<Example>
EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by the following example.

[Example 1] (Preparation of polyimide precursor varnish) 4,4′-diaminodiphenyl ether (Wakayama Seika Co., Ltd.) (hereinafter referred to as “4,4′-ODA”), 4,4 in a dimethylacetamide solvent Two types of diamines, '-bis (3-aminophenoxy) biphenyl (Mitsui Chemicals) (hereinafter referred to as “m-BP”) and pyromellitic dianhydride (Mitsubishi Gas Chemical Co., Ltd.) (Referred to as “PMDA”) was blended at a molar ratio of 4,4′-ODA: mBP: PMDA = 20: 30: 49.5. Then, the mixture was stirred for 4 hours or more to obtain a polyimide precursor varnish having a resin solid content ratio of 20 to 25% by mass.

(Preparation of Polyimide Film) The polyimide precursor varnish was applied on a glass plate with a 360 μm gap applicator using a desktop coater. Immediately after the coating, it was dried in a nitrogen atmosphere using an explosion-proof dryer. In drying, the temperature was raised from room temperature at 5 ° C./min and held at 300 ° C. for 1 hour. Then, it cooled naturally. After sufficiently cooling, the polyimide film was peeled off from the glass plate by being immersed in warm water for 24 hours to obtain a desired polyimide film sample. The film thickness after drying of the obtained polyimide film was 30 μm.

(Water absorption evaluation) The water absorption of the produced film sample was evaluated by the water absorption rate. The target sample was cut into a size of 50 mm × 50 mm, dried at 150 ° C. for 5 minutes, and immediately measured for mass. Then, it was immersed in ion exchange water at 23 ° C. for 24 hours. After immersion, the moisture attached to the surface of the sample taken out from the water tank was sufficiently blown off with an air gun, the mass was measured, and the water absorption was calculated from the above formula (1). A sample having a water absorption rate of 2.0% or less was rated as ○, and a sample having a water absorption rate exceeding 2.0% was rated as x.

(Glass transition temperature evaluation (heat resistance evaluation)) The glass transition temperature was evaluated about the polyimide film produced by the above-mentioned method. The measurement is performed by measuring the storage elastic modulus E ′ and the loss elastic modulus E ″ by temperature dispersion measurement (tensile mode) of solid viscoelasticity, and calculating the glass transition temperature from the peak value of loss tangent tan δ = E ″ / E ′. Derived. As a measuring apparatus, RSA-III manufactured by TA instruments was used. Those having a glass transition temperature of 290 ° C. or higher were evaluated as “B” and those having a glass transition temperature of less than 290 ° C. as “C”.

(Mechanical strength evaluation) The tensile mechanical strength of the produced polyimide film was measured. A sample was cut into a size of 140 mm length × 10 mm width, and 20 mm portions at both ends were used as a tensile region (actual measurement length was 100 mm). The tensile break elongation was measured by pulling a strip-shaped film sample at a speed of 50 mm / min. As a measuring device, AUTOGRAPH AGS-100D manufactured by Shimadzu Corporation was used. A sample having a tensile elongation at break (also referred to simply as “elongation at break”) of 55% or more was evaluated as ◯, and a sample having a tensile elongation at break of less than 55% was evaluated as x.

(Dielectric constant evaluation) About the polyimide film produced by the above-mentioned method, the dielectric constant was evaluated by the method based on JISK6911. Using an LCR meter HP4284A manufactured by Agilent Technologies, using a polyimide film sample left at 22 ° C. × 60% RH for 24 hours under the conditions of a frequency of 1 MHz, a main electrode = 18 mmφ, a guard electrode = 26 mmφ, and a counter electrode = 28 mmφ The evaluation was performed in a 22 ° C. × 60% RH environment.

Example 2 Two types of 4,4′-ODA and m-BP as diamine, PMDA as acid dianhydride, and a molar ratio of 4,4′-ODA: mBP: PMDA = 25: 25: 49.5 A polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1 except that it was blended. The film thickness was adjusted to be 30 μm (the following examples and comparative examples were similarly adjusted to be 30 μm).

Example 3 Two types of 4,4′-ODA and m-BP as diamine, PMDA as acid dianhydride, and 4,4′-ODA: mBP: PMDA = 12.5: 37.5: 49. A polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1 except that it was blended at a molar ratio of 5.

Example 4 Two types of 4,4′-ODA and m-BP as diamine, PMDA as acid dianhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (manufactured by JFE Chemical Co., Ltd.) ) (Hereinafter referred to as “s-BPDA”) in a molar ratio of 4,4′-ODA: mBP: PMDA: s-BPDA = 25: 25: 44.55: 4.95 Except for the above, a polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1.

[Example 5] Two types of 4,4'-ODA and m-BP as diamines, two types of PMDA and s-BPDA as acid dianhydrides, and 4,4'-ODA: mBP: PMDA: s-BPDA = A polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1 except that it was blended at a molar ratio of 25: 25: 35: 14.5.

[Example 6] As diamine, three kinds of 4,4′-ODA, m-BP, 1,3-bis (4-aminophenoxy) benzene (manufactured by Nippon Pure Chemicals, hereinafter referred to as 4-APB), acid Two types of dianhydrides, PMDA and s-BPDA, were blended at a molar ratio of 4,4′-ODA: mBP: 4-APB: PMDA: s-BPDA = 10: 25: 15: 35: 14.5 Except for this, a polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1.

[Comparative Example 1] Example 1 except that 4,4′-ODA as a diamine and PMDA as an acid dianhydride were blended in a molar ratio of 4,4′-ODA: PMDA = 50: 49.5. A polyimide precursor varnish was prepared and evaluated in the same manner as described above.

[Comparative Example 2] A polyimide precursor varnish as in Example 1, except that m-BP as a diamine and PMDA as an acid dianhydride were blended in a molar ratio of m-BP: PMDA = 50: 49.5. Were made and evaluated.

[Comparative Example 3] 2,4'-ODA and m-BP as diamines, PMDA and s-BPDA as two types as acid dianhydrides, and 4,4'-ODA: mBP: PMDA: s- A polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1 except that it was blended in a molar ratio of BPDA = 25: 25: 24.5: 25.

[Comparative Example 4] 4,4 ′-(m-phenylenediisopropylidene) dianiline (manufactured by Mitsui Chemicals Fine) (hereinafter referred to as “Bisaniline M”), m-BP, dianhydride as diamine A polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1 except that PMDA was blended at a molar ratio of bisaniline M: mBP: PMDA = 25: 25: 49.5.

[Comparative Example 5] 2,2′-dimethyl-4,4′-diaminobiphenyl (manufactured by Wakayama Seika) (hereinafter referred to as “m-tolidine”), m-BP, and acid dianhydride A polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1 except that PMDA was blended at a molar ratio of m-tolidine: mBP: PMDA = 25: 25: 49.5.

[Comparative Example 6] 2,4'-ODA and m-BP as diamine, PMDA as acid dianhydride, 1 type, 4,4'-ODA: mBP: PMDA = 7.5: 42.5 : A polyimide precursor varnish was prepared and evaluated in the same manner as in Example 1 except that it was blended at a molar ratio of 49.5.

Table 1 shows the preparation ratio of the polyimide acid varnish, and Table 2 shows the physical property values.

It was confirmed that the polyimide film according to this example was excellent in low dielectric constant. For example, the dielectric constant of the polyimide film of Comparative Example 1 was 3.61, whereas the dielectric constant of the polyimide film according to Example 2 was 3.35, and the dielectric constant of the polyimide film according to Example 5 was 3. 33.

According to this example, in any polyimide film, the glass transition temperature is 290 ° C. or more, the water absorption is 2.0% or less, and the tensile elongation at break is 55% or more, in addition to excellent mechanical strength, It can be seen that necessary and sufficient characteristics can be provided both in terms of water resistance and low water absorption.

This application claims priority based on Japanese Patent Application No. 2012-57315 filed on March 14, 2012, the entire disclosure of which is incorporated herein.

The polyimide resin obtained from the polyimide precursor varnish according to the present invention has excellent insulating properties and mechanical properties, and also has excellent low water absorption and heat resistance. can do. Examples of suitable applications include various electronic parts such as insulated wires, heat-resistant tapes, heat-resistant paints, and aerospace adhesives. Also, for example, heat resistant films, printed wiring board substrates, various industrial sliding parts such as automobiles and aerospace, seamless belts for OA equipment, heat radiation members, electromagnetic wave shielding members, battery binders, solar cell members It is suitable as an insulating protective material for dental members and transparent conductors. In addition, since low transmission loss and low dielectric constant can be realized, it is particularly suitable for applications such as insulated wires or windings.

DESCRIPTION OF SYMBOLS 1 Insulated electric wire 2 Heat resistant tape 10 Conductor 20 Insulation coating layer 21 1st insulation coating layer 22 2nd insulation coating layer 30 Support base material 31 Joining layer

Claims (12)

A polyimide precursor varnish comprising a composition containing a polyimide precursor and a solvent,
In the case of a polyimide film having a coating film thickness after drying of 20 to 60 μm obtained by coating the composition, heating at 5 ° C./min, 300 ° C. for 1 hour in a nitrogen atmosphere,
Glass transition temperature is 290 ° C or higher,
A polyimide precursor varnish having a water absorption of 2.0% or less and a tensile elongation at break of 55% or more. The polyimide precursor is
It was obtained by polycondensation of diamine and acid dianhydride,
The diamine is at least 19 mol% and not more than 56 mol% with respect to the total amount of the diamine, and the diamine component A represented by the chemical formula (1) and 44 mol% or more and 81 mol% with respect to the total amount of the diamine. The diamine component B represented by the following chemical formula (2) is a constituent component,
The acid dianhydride includes at least an acid dianhydride component C represented by the chemical formula (3) that is 60 mol% or more and 100 mol% or less with respect to the total amount of the acid dianhydride, and The polyimide precursor varnish of Claim 1 which uses the acid dianhydride component D shown by Chemical formula (4) which is 0 mol% or more and 40 mol% or less with respect to the whole quantity as a structural component.

(Wherein X represents a divalent group such as a single bond, oxygen atom, sulfur atom, sulfone group, carbonyl group, methylene group, isopropylidene group or hexafluoroisopropylidene group)

(In the formula, Y represents a divalent group of a single bond, an oxygen atom, a sulfur atom, a sulfone group, a carbonyl group, a methylene group, an isopropylidene group or a hexafluoroisopropylidene group) The polyimide precursor is
The total of the diamine component A and the diamine component B is 47.5 to 52.5 mol% with respect to the total of the diamine and the acid dianhydride, and the acid dianhydride component C and the acid dianhydride component D. The polyimide precursor varnish according to claim 2, wherein the polyimide precursor varnish is copolymerized in a range satisfying 47.5 to 52.5 mol%. 4. The polyimide precursor varnish according to claim 2, wherein the diamine component B is 4,4′-bis (3-aminophenoxy) biphenyl described by the chemical formula (5).

The polyimide precursor varnish according to any one of claims 2 to 4, wherein the diamine component A is 4,4'-diaminodiphenyl ether represented by the chemical formula (6).
The polyimide according to any one of claims 2 to 5, wherein the acid dianhydride component D is 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride described by the chemical formula (7). Precursor varnish.

A polyimide resin formed by imidizing a molded product obtained from the polyimide precursor varnish according to any one of claims 1 to 6. The polyimide resin according to claim 7, which is used as an insulating coating material for covering a conductor. Conductors,
An insulating coating material for covering the conductor, and an electronic component comprising:
An electronic component comprising a polyimide resin, wherein at least a part of the insulating coating material is formed by imidizing a molded product obtained from the polyimide precursor varnish according to any one of claims 1 to 6. A support substrate;
Comprising a bonding layer formed on the support substrate,
The heat-resistant tape, wherein the supporting base material contains, as a component, a polyimide resin formed by imidizing a molded product obtained from the polyimide precursor varnish according to any one of claims 1 to 6. A heat resistant paint comprising the polyimide precursor varnish according to any one of claims 1 to 6. An aerospace adhesive comprising the polyimide precursor varnish according to any one of claims 1 to 6, or a gel film formed from the polyimide precursor varnish.

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