JP5144361B2 - Polyamic acid composition and polyimide resin molded body - Google Patents

Description

  The present invention relates to a polyamic acid composition and a polyimide resin molded body.

Polyimide resins are useful for applications in the electronics field and OA equipment field, and are used as insulating films and protective coatings on semiconductor devices, or as belts and tubes for functional parts for copying machines and printers. In particular, wholly aromatic polyimide resins are often selected and used for the above applications because of their excellent heat resistance, mechanical properties, and electrical properties. To obtain the above-mentioned polyimide resin has been polyimide precursor solution is conventionally used, as such a polyimide precursor solution, a polyamic acid represented by the following formula _{(I) (R 1, R} 2 is an aromatic A polyamic acid solution having a group as a solute is known.

  The polyimide precursor such as polyamic acid is a solution of a polymer having a high degree of polymerization (where n represents the degree of polymerization). When obtaining a polyimide film from these polymer solutions, in general, this polymer solution is applied to an aluminum or stainless steel mold, heated to remove the solvent and imidize, and then demolded to remove the polyimide. It becomes a resin molding.

  Moreover, it is known that a polyimide film having good physical properties can be obtained from a solution containing a salt composed of these monomers instead of a polymer by combining specific monomers. For example, a polyimide precursor solution containing, as a solute, a salt obtained from a compound having an amino group and a compound having a carboxyl group shown below, although containing a high concentration of a monomer salt, A low-strength and high-strength polyimide coating or film is obtained from this solution (see, for example, Patent Document 1).

In the general formula (II), R represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and the four carbonyl groups are directly connected to different carbon atoms in the residue. Two of the two are paired and bonded to adjacent carbon atoms in the carbon 6-membered ring, and R ′ represents a divalent aromatic residue having at least one carbon 6-membered ring. In the general formula (III), R ″ represents a tetravalent aromatic residue containing at least one carbon 6-membered ring, and the four carbonyl groups are directly connected to different carbon atoms in the residue. Two of the four are paired and bonded to adjacent carbon atoms in the carbon six-membered ring. R ′ ″ is each selected from hydrogen and an alkyl group having 1 to 5 carbon atoms.
Japanese Patent No. 3262514

  However, when a polyimide resin molded body is obtained by applying the above-mentioned polyimide precursor polymer solution having a high polymerization degree to a mold and then imidizing and removing the mold, the polymer solution having a high polymerization degree can be applied. In order to achieve a high viscosity, there is a problem that the solute concentration must be lowered. Conversely, in order to increase the productivity, if the solute concentration is increased, the viscosity of the solution increases and the coating becomes impossible. was there. Moreover, even if the coating can be performed, a film having excellent mechanical and thermal characteristics cannot be obtained because a desired molecular weight cannot be obtained.

  In addition, as a polyimide precursor, a polyamic acid which is a polymer of a compound of 4,4′-diaminodiphenyl ether and 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, which has been conventionally used, is a precursor. Is soluble in a solvent such as NMP (N-methyl-2-pyrrolidone) but becomes insoluble and precipitates upon imidization. There is a problem that satisfactory film appearance or satisfactory film strength cannot be obtained by using a coating liquid on which a polyimide resin is deposited.

The technique of Patent Document 1 has been made to solve the above problems. However, when a polyimide coating film or film is obtained by the method proposed in Patent Document 1, since the shrinkage accompanying imidization on the mold is large, as in the case of using a conventional high polymerization degree polyimide precursor, When the film is formed, partial non-uniform contraction in the axial direction occurs, resulting in variations in film thickness or resistance variations in the case of conducting a conductive treatment. In addition, the pressing force on the mold due to shrinkage is high, and it is difficult to remove the mold. Furthermore, since the condensed water generated with imidization causes surface failure such as bubbles during film formation, it is difficult to obtain a film having a good surface appearance.
There is also a polyimide resin that is 100% imidized resin and is soluble in a solvent. For example, polyetherimide (trade name ULTEM100: manufactured by GE Plastics, Inc.) is an example, but in order to ensure solubility, the degree of freedom of the molecular skeleton is increased, resulting in low strength characteristics.

  The present invention is a polyamic acid composition capable of obtaining a polyimide resin molded article having uniform, excellent mechanical properties, and good appearance by suppressing shrinkage and generation of condensed water accompanying an imidization reaction when obtaining a molded article. The purpose is to provide goods. Another object of the present invention is to provide a polyimide resin molded article that is uniform, excellent in mechanical properties, and has a good appearance.

As a result of intensive studies, the present inventors have found that the following present invention can solve the above problems, and have completed the present invention.
That is, the invention according to claim 1 is synthesized using a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and 90 to 99 mol% is imidized. Polyamic acid,
A solvent,
It is a polyamic acid composition characterized by containing.

(In general formula (1), X represents a divalent linking group. In general formula (2), Y represents a divalent linking group. Each NH ₂ in the two benzene rings of general formula (2). The bonding position of is asymmetric from the viewpoint of Y.)

  In the invention according to claim 2, the compound represented by the general formula (1) is a compound represented by the following general formula (3), and the compound represented by the general formula (2) is represented by the following general formula ( It is a compound represented by 4), It is a polyamic acid composition of Claim 1 characterized by the above-mentioned.

  The invention according to claim 3 is characterized in that the polyamic acid is a compound represented by the following general formula (5) together with a compound represented by the general formula (1) and a compound represented by the general formula (2) 3. The polyamic acid composition according to claim 1, wherein the composition is synthesized using at least one of the compounds represented by the following general formula (6).

The invention according to claim 4 has a structure derived from a compound represented by the following general formula (1) as a structure derived from an acid, and a compound represented by the following general formula (2) as a structure derived from a diamine. a seamless tubing which have a structure derived from,
A polyimide resin molded article having a molding shrinkage in the axial direction represented by the following formula (1) of 0.5% or more and 1.5% or less .
Formula (1): Shrinkage rate (%) = 100 × (L0−L1) / L0
(In the formula (1), L0 represents the length between markings when a line is drawn in the axial direction of the dried seamless tubular product before firing and marked at both ends and the center of the line. And represents the length between the markings of the seamless tubular product after firing .

(In general formula (1), X represents a divalent linking group. In general formula (2), Y represents a divalent linking group. The bonding positions of two NH ₂ in general formula (2) are as follows. Asymmetrical with respect to Y.)

The invention according to claim 5 is an average film thickness measured by a micrometer, and is a ratio (A / B) between an average film thickness A at both ends in the axial direction and an average film thickness B at the central portion in the axial direction. ) Is 1.03 or less, the polyimide resin molded article according to claim 4 .

The invention according to claim 6 is the polyimide resin molded article according to claim 4 or 5 , wherein the tensile elastic modulus measured at a pulling speed of 20 mm / min in accordance with JISK7161 is 3.5 GPa or more. .

According to the first aspect of the invention, it is possible to obtain a polyimide resin molded body that is uniform, excellent in mechanical properties, and has a good appearance by suppressing shrinkage and generation of condensed water associated with an imidization reaction when obtaining a molded body. It is possible to provide a polyamic acid composition capable of
According to the invention which concerns on Claim 2, the effect of suppressing shrinkage | contraction accompanying the imidation reaction at the time of obtaining a molded object, and generation | occurrence | production of condensed water becomes remarkable.
According to the invention which concerns on Claim 3, compared with another material, the polyimide resin molding which has favorable mechanical strength is obtained.

According to the invention which concerns on Claim 4, the polyimide resin molded object which is uniform and excellent in a mechanical characteristic, and has a favorable external appearance can be obtained.
According to the invention according to claim 4 , a seamless tubular product having a uniform thickness can be obtained, and further, when the molded body is produced, the molded body can be easily released from the cylindrical mold or the like, It can have a better appearance.

According to the invention which concerns on Claim 5 , the seamless tubular thing of uniform thickness is obtained, and also the polyimide resin molded object with uniform mechanical characteristics, such as an electrical resistance, is obtained.
According to the invention which concerns on Claim 6 , compared with another material, the polyimide resin molding which has favorable mechanical strength is obtained.

An embodiment of the present invention will be described.
The polyamic acid composition of the present embodiment is synthesized using a compound represented by the following general formula (1) and a compound represented by the following general formula (2), and 90 mol% or more and 99 mol% or less is imidized. It contains polyamic acid and a solvent. Hereinafter, the “polyamic acid in which 90 mol% to 99 mol% is imidized” may be referred to as “partially imidized polyamic acid”.

In general formula (1), X represents a divalent linking group. In general formula (2), Y represents a divalent linking group. The bonding positions of NH ₂ in the two benzene rings of the general formula (2) are asymmetric from the viewpoint of Y.

The partially imidized polyamic acid composition of this embodiment can suppress shrinkage and generation of condensed water associated with an imidization reaction when obtaining a molded body. As a result, it is possible to obtain a polyimide resin molded body that is uniform, excellent in mechanical properties, and has a good appearance.
The polyamic acid contained in the partially imidized polyamic acid composition of the present embodiment is 90 to 99 mol% imidized, and the remaining 1 to 10 mol% is imidized to form a polyimide resin molded body. Can be obtained. For this reason, the shrinkage | contraction and generation | occurrence | production of condensed water accompanying an imidation reaction can be suppressed to an appropriate amount, As a result, the molded object obtained can have a favorable external appearance. For example, when the target molded body is a film, the partially imidized polyamic acid composition of the present embodiment can suppress shrinkage and generation of condensed water accompanying the imidization reaction to an appropriate amount during film formation, and thus has a good appearance. A film can be obtained.

  In addition, the partially imidized polyamic acid composition of the present embodiment is a polyimide resin molded body that is uniform and excellent in mechanical properties and maintains high strength without using molecules with high hygroscopicity by devising a molecular skeleton. Can be obtained. Specifically, when the polyamic acid is partially imidized, it is generally precipitated as a solid content, but the partially imidized polyamic acid composition of the present embodiment is represented by the general formula (1). Since the polyamic acid synthesized using the compound and the compound represented by the general formula (2) is used, even when 90 mol% or more and 99 mol% or less is imidized, it does not precipitate as a solid content. Accordingly, the polyimide resin molded body obtained by further imidization is a polyimide resin molded body that is uniform and excellent in mechanical properties and maintains high strength.

The partially imidized polyamic acid in the partially imidized polyamic acid composition of this embodiment will be described.
The partially imidized polyamic acid is synthesized using the compound represented by the general formula (1) and the compound represented by the general formula (2).
The compound represented by the general formula (1) will be described.
In the general formula (1), X represents a divalent linking group. Specific examples include an oxygen atom, CH ₂ and C═O, and an oxygen atom is particularly preferable.

  The compound represented by the general formula (1) is particularly preferably a compound in which X is an oxygen atom, that is, a compound represented by the following general formula (3).

The compound represented by the general formula (2) will be described.
In the general formula (2), Y represents a divalent linking group. Specific examples include an oxygen atom, CH ₂ and C═O, and an oxygen atom is particularly preferable.

In the compound represented by the general formula (2), the bonding positions of the NH ₂ in the two benzene rings are asymmetric with respect to Y. Specifically, examples of the bonding position of each NH ₂ in the two benzene rings include 3, 4 ′, 2, 3 ′, and 2, 4 ′ when viewed from the carbon atom bonded to —Y— 4 ′ is particularly preferred.

In the compound represented by the general formula (2), Y is an oxygen atom, and the bonding position of each NH ₂ in the two benzene rings is 3,4 ′ as seen from the carbon atom bonded to —Y—. That is, the compound represented by the following general formula (4) is particularly preferable.

  As described later, the partially imidized polyamic acid has a compound represented by the general formula (1) and a compound represented by the general formula (1) in order to make the tensile elastic modulus of the polyimide resin molded body obtained by further imidization 3.5 GPa or more. It is preferable to synthesize | combine using at least one of the compound represented by following General formula (5) and the compound represented by following General formula (6) with the compound represented by General formula (2). The amount of the compound represented by the following general formula (5) and the compound represented by the following general formula (6) is appropriately adjusted so that the tensile elastic modulus is 3.5 GPa or more.

-Solvent-
In order to obtain a partially imidized polyamic acid composition using a material containing the compound represented by the general formula (1) and the compound represented by the general formula (2), the material is used in an organic polar solvent. It is preferable to prepare a polyamic acid solution (in this specification, the polyamic acid composition before being partially imidized may be referred to as a “polyamic acid solution”).
The organic polar solvent includes the compound represented by the general formula (1) and the compound represented by the general formula (2), the compound represented by the general formula (5), and the general formula (6). In the case of using at least one of the compounds represented by the formula, there is no particular limitation as long as these compounds can be dissolved.

  Examples of the organic polar solvent include sulfoxide solvents dimethyl sulfoxide, diethyl sulfoxide, etc., formamide solvents N, N-dimethylformamide, N, N-diethylformamide, etc., acetamide solvents N, N-dimethylacetamide, N, N-diethylacetamide, pyrrolidone solvents N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, etc., phenol solvents pyrrolidonephenol, o-, m- or p-cresol, xylenol, halogenated phenol, Examples thereof include catechol and the like, ether solvents such as tetrahydrofuran, dioxane, dioxolane and the like, or hexamethylphosphoramide, γ-butyrolactone and the like.

  These organic polar solvents can be used singly or in combination of two or more, and can also be used by mixing with other solvents. When used as a mixture, aromatic hydrocarbons such as xylene and toluene can also be used.

  When the polyamic acid solution is prepared in the above solvent, the solid content concentration of the polyamic acid solution is appropriately adjusted to an amount suitable for molding the polyimide resin molded body. For example, when a seamless tubular product is molded as a molded body, the solid content concentration of the polyamic acid solution is preferable so that the viscosity is suitable for application to a cylindrical mold or the like, specifically, 5% by mass or more. 50 mass% or less is preferable, and 10 mass% or more and 30 mass% or less are especially suitable.

-Additives-
Moreover, when manufacturing a polyimide resin molded object, you may mix another electroconductive substance as an additive with the said polyamic acid solution from a viewpoint of giving electroconductivity.
The additive used in the polyamic acid solution is preferably carbon black having conductivity because it is easy to adjust the electric resistance value. In particular, an oxidation treatment is performed because of dispersion stability and stability of electric resistance. An oxidized carbon black having a pH of 5.0 or less is suitable.

  Oxidized carbon black is a carbon black having a carboxyl group, a quinone group, a lactone group, a hydroxyl group, etc. added to the surface of the carbon black by oxidation treatment. Examples of the oxidation treatment include an air oxidation method in which a reaction is caused by contact with air in a high temperature (about 270 ° C. to about 400 ° C.) atmosphere, a temperature oxidation method at room temperature (about 20 ° C.), a contact method, and a furnace black method. is there.

Examples of the carbon black include ketchen black and acetylene black. Also, other conductive particles can be used as long as a predetermined electric resistance can be obtained. Examples of other conductive particles include metals such as aluminum and nickel, metal oxide compounds such as yttrium oxide and tin oxide, and potassium titanate. Further, an ion conductive material such as LiCl, or a conductive polymer material such as polyaniline, polypyrrole, polysulfone, or polyacetylene can be added.
These can be used alone or in combination of two or more.

  The partially imidized polyamic acid composition of the present embodiment can be obtained by imidizing 90 mol% or more and 99 mol% or less of the polyamic acid contained in the polyamic acid solution. As imidization in this case, it is preferable to separate unnecessary solvent after stirring and refluxing at 150 ° C. to 180 ° C. for an appropriate time.

  The partially imidized polyamic acid is 90 to 99 mol% imidized, preferably 95 to 99 mol% imidized, and preferably 97 to 99 mol% imidized. More preferred. When the imidization ratio of the polyamic acid is less than 90 mol%, shrinkage due to imidization increases at the time of molding, so that the film thickness becomes non-uniform or further difficult to separate from the mold, and exceeds 99 mol%. The molding shrinkage disappears and the smoothness becomes poor.

Here, the imidation ratio of the polyamic acid composition is determined as follows.
About 1 g of a sample is taken in a container, titrated with a 0.1 N KOH ethanol solution using a phenolphthalein solution, and the amount of KOH (mg) required for the titration is 18% by mass of the polyamic acid composition. The value converted to the hour value is defined as the acid value (Av). The following formula (A) is used to calculate the acid value (Av).
Formula (A)
Av = x × 0.1 × 56 / X × 18 / NV
In the formula (A), x represents a titration amount (mg) with a 0.1 N KOH solution, X represents an amount (g) of the polyamic acid composition, and NV represents a concentration (mass%) of the polyamic acid composition. Indicates.

Based on the acid value (Av (PAA)) measured for the polyimide precursor solution before imidization and the acid value (Av (PI)) measured for the partially imidized polyamic acid solution subjected to imidization, The imidation ratio of a polyamic acid composition is calculated | required using Formula (B).
Formula (B)
(Imidization rate) = 100−Av (PI) / Av (PAA) × 100

  The partially imidized polyamic acid composition of the present embodiment preferably has a viscosity of 18 · s / 30 ° C. or higher and 24 · s / 30 ° C. or lower, and 20 · s / 30 ° C. or higher and 23 · s / 30 ° C. or lower. More preferably.

<Polyimide resin molding>
The polyimide resin molded body of this embodiment has a structure derived from a compound represented by the following general formula (1) as a structure derived from an acid, and is represented by the following general formula (2) as a structure derived from a diamine. It has a structure derived from a compound. Uniform, excellent mechanical properties and good appearance. However, the polyimide resin molded body of the present embodiment is a seamless tubular product having the above-described structure, and a polyimide whose axial shrinkage in the axial direction represented by the following formula (1) is 0.5% or more and 1.5% or less. Apply resin molding.
Formula (1): Shrinkage rate (%) = 100 × (L0−L1) / L0
(In the formula (1), L0 represents the length between markings when a line is drawn in the axial direction of the dried seamless tubular product before firing and marked at both ends and the center of the line. And represents the length between markings of the seamless tubular product after firing.

In general formula (1), X represents a divalent linking group. In general formula (2), Y represents a divalent linking group. The bonding positions of the two NH ₂ in the general formula (2) are asymmetric with respect to Y. The preferable aspect of General formula (1) and General formula (2) is the same as the preferable aspect of General formula (1) and General formula (2) in the partial imidation polyamic acid composition of already described this embodiment.

  The polyimide resin molded body of the present embodiment preferably has a tensile elastic modulus of 3.5 GPa or more, more preferably 3.7 Pa or more, in terms of having good mechanical strength compared to other materials. More preferably, it is 3.8 Pa or more.

  The shape of the polyimide resin molded body of the present embodiment is not particularly limited, but is preferably a film, and more preferably a seamless tubular product (seamless film).

  When the polyimide resin molding of this embodiment is a seamless tubular product, the axial molding shrinkage is preferably 0.5% or more and 1.5% or less, and is 0.8 or more and 1.3 or less. Is more preferable, and 1.0 to 1.3% is still more preferable. When the molding shrinkage in the axial direction is 0.5% or more and 1.5% or less, a seamless tubular product having a uniform thickness can be obtained, and a cylinder for producing a molded product (seamless tubular product) to be described later. The molded product can be easily released from the metal mold or the like, and can have a better appearance.

  Moreover, when the polyimide resin molding of this embodiment is a seamless tubular product, the ratio (A / B) between the average film thickness A at both ends in the axial direction and the average film thickness B at the central part in the axial direction is It is preferably 1.03 or less, and more preferably 1.02 or less. When the (A / B) is 1.03 or less, a seamless tubular product having a uniform thickness is obtained, and a polyimide resin molded product having uniform mechanical properties such as electric resistance is obtained.

  The polyimide resin molded body of this embodiment preferably has a tensile strength of 115 MPa or more from the viewpoint of the molded body breaking strength.

  As for the polyimide resin molding of this embodiment, it is more preferable that tensile elongation is 40% or more at the point of the breaking elongation of a molded object.

  This embodiment has a structure derived from the compound represented by the general formula (1) as a structure derived from an acid, and a structure derived from the compound represented by the general formula (2) as a structure derived from a diamine. The polyimide resin molding of the form can be produced by further imidizing the partially imidized polyamic acid composition of the present embodiment described above. That is, by using a partially imidized polyamic acid synthesized using the compound represented by the general formula (1) and the compound represented by the general formula (2), the general formula (1) And a structure derived from the compound represented by (2).

  In the partially imidized polyamic acid composition of the present embodiment described above, the partially imidized polyamic acid composition to be used is represented by the compound represented by the general formula (1) and the general formula (2). When synthesized with at least one of the compound represented by the general formula (5) and the compound represented by the general formula (6) together with the compound, the general formula (5) or the general formula (6) It has a structure derived from the compound represented by.

  Further, by using the partially imidized polyamic acid composition of the present embodiment as described above, since there is little imidization after application to the die described later, the tensile elastic modulus is 3.5 GPa or more, the axial molding shrinkage rate Can be controlled to 0.5% or more and 1.5% or less, and (A / B) can be controlled to 1.03 or less. Furthermore, the tensile strength can be controlled to 115 MPa or more, and the tensile elongation can be controlled to 40% or more.

The manufacturing method of the polyimide resin molded body of this embodiment will be described as a representative case where the molded body is a seamless tubular product.
First, the partially imidized polyamic acid composition of the present embodiment described above is applied to the inner surface or outer surface of a mold that is a cylindrical substrate. In addition, instead of the mold, cylindrical molds made of various known materials such as resin, glass, and ceramic can be used. It is also possible to appropriately select to provide a glass coat or ceramic coat on the surface of the cylindrical mold or cylindrical mold, and to use a silicone-based or fluorine-based release agent.

  Also, by moving the film thickness control mold with the clearance adjusted to the cylindrical mold through the cylindrical mold in parallel, the excess solution is eliminated and the thickness of the solution on the cylindrical mold is made uniform. You may apply the method to do. If the uniform thickness control of the solution is performed at the stage of applying the solution onto the cylindrical mold, it is not necessary to use a film thickness control mold.

Next, the cylindrical mold coated with the partially imidized polyamic acid composition is placed in a heating environment, and drying is performed to volatilize 30% by mass or more, preferably 50% by mass or more, of the contained solvent. At this time, the drying temperature is preferably in the range of 50 to 200 ° C.
Furthermore, this cylindrical mold is heated at a temperature of 150 ° C. to 450 ° C. to sufficiently advance the imide conversion reaction. Insufficient imidization results in poor mechanical and electrical properties, and must be heated to a temperature at which imide conversion is completed.
Thereafter, the polyimide resin can be removed from the cylindrical mold to obtain an endless belt-shaped polyimide belt (polyimide resin molding).

  Hereinafter, the present embodiment will be described more specifically with reference to examples. However, it is not limited to these examples.

<Example 1>
(Preparation of polyamic acid composition)
In a flask equipped with a Dean-Stark trap, a reflux tube, and a mechanical stirrer, 14.40 g of 3,4'-diaminodiphenyl ether (ODA, a compound represented by the general formula (4)) in a dry air atmosphere , NMP 150 g, and toluene 30 g in a mixed solvent and kept at 10 ° C. To this, 11.64 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA, a compound represented by the general formula (5)) and 4,4′-oxydiphthalic dianhydride (ODPA) The compound represented by the general formula (3)) was gradually added, and stirring was continued at 10 ° C. for 1 hour and then at 25 ° C. for 48 hours to obtain a polyimide precursor solution. After further heating, stirring and refluxing at 165 ° C. for 6 hours, draining water and toluene in the trap, further stirring for 0.5 hour, cooling to room temperature, and a copolymer of the following two structural units: A partially imidized polyamic acid composition was obtained. At this time, the viscosity of the composition (viscosity at 30 ° C. measured with a B-type viscometer manufactured by Tokyo Keiki Co., Ltd.) was 21.7 Pa · s, and the imidization ratio measured by the method described above was 95 mol%. The viscosity, solid content concentration, and imidation ratio of the partially imidized polyamic acid composition are shown in Table 1 (the same applies to the following examples and comparative examples).

(Preparation of polyimide film (polyimide resin molding))
The obtained partially imidized polyamic acid composition was uniformly applied to a thickness of 0.44 mm on a cylindrical mold having an outer diameter of Φ168 mm, and the mold was rotated at 10 rpm in a drying furnace at 140 ° C. Dry for 30 minutes. Thereafter, the mold was allowed to stand in a firing furnace and fired at 300 ° C. for 30 minutes. After cooling the mold, the shrinkage rate was measured, and then the mold was removed from the mold to obtain a polyimide film made of a polyimide resin having the following structure (m and n represent the number of repetitions). The molding shrinkage in the axial direction and the (A / B) measured as follows for the obtained polyimide film are shown in Table 1 (the same applies to the following examples and comparative examples).

(Measurement of mechanical properties of polyimide film)
Furthermore, the result of having measured the following mechanical properties of the obtained polyimide film is shown in Table 1 (the same applies to the following Examples and Comparative Examples).
Glass transition temperature (Tg)
It measured using the differential thermal analyzer Pyris1 by PERKIN-ELMER. The heating rate was measured at 2 ° C./min.

Linear expansion coefficient (CTE)
Measurement was performed using a thermomechanical analyzer TMA2940 manufactured by TA Instruments. The linear expansion coefficient was calculated from the amount of expansion from 50 ° C to 100 ° C.

Tensile modulus, tensile strength and tensile elongation were measured using an Intesco precision universal material testing machine 2020 type. Using a dumbbell No. 3 test piece (JISK7161), the measurement was performed at a tensile speed of 20 mm / min.

Mold shrinkage in the axial direction Three lines are drawn in the axial direction using oil-based ink at an arbitrary position of the dry film on the mold. Mark the both ends and the center of the line and measure the distance between the markings (L0). The length between the markings is measured again after firing (L1).
From the above L0 and L1, the molding shrinkage rate in the axial direction was determined by the following formula (the average of three locations was determined).
Shrinkage rate (%) = 100 × (L0−L1) / L0.

Edge / center thickness ratio (A / B)
The film thickness after baking demolding is determined with a micrometer. Here, the ratio of the end portion / center portion film thickness = the average value of the end portion film thickness / the average value of the center portion film thickness (n = 5).

(Evaluation of film appearance characteristics)
The results of evaluating the following appearance characteristics of the obtained polyimide film are shown in Table 2 (the same applies to the following Examples and Comparative Examples).
Surface gloss It was evaluated by visual judgment. The evaluation criteria are ○ for those with good clarity and gloss. Poor clarity, x for mat-like items. The middle is △.

Surface failure Evaluated by visual judgment. The evaluation criteria are ○ for smooth and no failure. Those with harmful protrusion-like failure or bubble-like failure were marked with x.

Mold releasability Evaluated by ease of mold release. The evaluation criteria are ○ that can be easily removed from the mold by close contact with air. Those that could not be easily removed were marked with x.

Variation in film thickness A total of 24 points in the axial direction of the belt and 8 points in the circumferential direction were measured with a micrometer at equal intervals. The difference between the maximum and minimum values is less than 7 microns. The thing of 7 microns or more was set as x.

<Example 2>
(Preparation of polyamic acid composition)
Using the same polyimide precursor solution as in Example 1, stirring / refluxing at 165 ° C. for 6 hours was changed to stirring / refluxing at 165 ° C. for 10 hours, water in the trap and toluene were removed, and stirring was continued for 0.5 hour. A partially imidized polyamic acid composition was obtained in the same manner as in Example 1 except that the composition was cooled to room temperature. At this time, the composition had a viscosity of 22.9 Pa · s and an imidization ratio of 97 mol%. Further, the same evaluation as in Example 1 was performed.

<Example 3>
(Preparation of polyamic acid composition)
A partially imidized polyamic composition was obtained in the same manner as in Example 1 except that the same polyimide precursor solution as in Example 1 was used, and stirring and refluxing were carried out at 165 ° C. for 6 hours and stirring at 165 ° C. for 4 hours. It was. At this time, the composition had a viscosity of 20.4 Pa · s and an imidization ratio of 92 mol%. Further, the same evaluation as in Example 1 was performed.

<Comparative Example 1>
180 g of commercially available polyetherimide resin (ULTEM1000 manufactured by Nippon GE Plastics) was dissolved in 820 g of NMP (performed in a stirring tank with stirring blades maintained at 60 ° C.) to obtain a solution. The obtained solution had a viscosity of 16.1 Pa · s and an imidization ratio of 100 mol%. Furthermore, in Example 1, this solution was used in place of the partially imidized polyamic acid composition, and instead of baking at 300 ° C. for 30 minutes, the sample was further dried at 250 ° C. for 30 minutes, and the same as in Example 1. Thus, a polyimide film was obtained. Further, the same evaluation as in Example 1 was performed.

<Comparative example 2>
(Preparation of polyimide precursor solution)
In a flask equipped with a mechanical stirrer, 14.63 g of 4,4′-diaminodiphenyl ether (compound represented by ODA general formula (6)) was dissolved in 150 g of NMP and kept at 10 ° C. in a dry air atmosphere. . To this was gradually added 21.50 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (BPDA, a compound represented by the general formula (5)) at 10 ° C. for 1 hour, and then at 25 ° C. Was continued for 48 hours to obtain a polyimide precursor solution. At this time, the viscosity of the solution was 24.8 Pa · s, and the imidization ratio was 0 mol%.
In Example 1, a polyimide precursor solution was used in place of the partially imidized polyamic acid composition, and the polyimide was changed in the same manner as in Example 1 except that the baking at 300 ° C. for 30 minutes was changed to 320 ° C. for 30 minutes. A film was obtained. Further, the same evaluation as in Example 1 was performed.

<Comparative Example 3>
In Example 1, a partially imidized polyamic solution was obtained in the same manner as in Example 1 except that stirring and refluxing at 165 ° C. for 6 hours was changed to stirring and refluxing at 165 ° C. for 2 hours. At this time, the viscosity of the solution was 16.6 Pa · s, and the imidization ratio was 83 mol%. Further, the same evaluation as in Example 1 was performed.

<Comparative example 4>
In Example 1, a partially imidized polyamic solution was obtained in the same manner as in Example 1 except that stirring and refluxing at 165 ° C. for 6 hours was changed to stirring and refluxing at 165 ° C. for 3 hours. At this time, the viscosity of the solution was 17.9 Pa · s, and the imidization ratio was 88 mol%. Further, the same evaluation as in Example 1 was performed.

Claims (6)

A polyamic acid synthesized using a compound represented by the following general formula (1) and a compound represented by the following general formula (2), wherein 90 mol% or more and 99 mol% or less are imidized;
A solvent,
A polyamic acid composition comprising:

(In general formula (1), X represents a divalent linking group. In general formula (2), Y represents a divalent linking group. Each NH ₂ in the two benzene rings of general formula (2). The bonding position of is asymmetric from the viewpoint of Y.) The compound represented by the general formula (1) is a compound represented by the following general formula (3), and the compound represented by the general formula (2) is a compound represented by the following general formula (4). The polyamic acid composition according to claim 1, wherein the polyamic acid composition is present.

The polyamic acid is represented by the compound represented by the following general formula (5) and the compound represented by the following general formula (6) together with the compound represented by the above general formula (1) and the compound represented by the above general formula (2). The polyamic acid composition according to claim 1, wherein the polyamic acid composition is synthesized using at least one of the compounds.

Seamless to have a structure derived from a structure derived from an acid having a structure derived from a compound represented by the following general formula (1), a structure derived from a diamine compound represented by the following general formula (2) A tubular object,
A polyimide resin molded article having a molding shrinkage in the axial direction represented by the following formula (1) of 0.5% or more and 1.5% or less .
Formula (1): Shrinkage rate (%) = 100 × (L0−L1) / L0
(In the formula (1), L0 represents the length between markings when a line is drawn in the axial direction of the dried seamless tubular product before firing and marked at both ends and the center of the line. And represents the length between markings of the seamless tubular product after firing.

(In general formula (1), X represents a divalent linking group. In general formula (2), Y represents a divalent linking group. The bonding positions of two NH ₂ in general formula (2) are as follows. Asymmetrical with respect to Y.) The average film thickness measured with a micrometer, and the ratio (A / B) between the average film thickness A at both ends in the axial direction and the average film thickness B at the central portion in the axial direction is 1.03 or less. The polyimide resin molded body according to claim 4 , wherein the polyimide resin molded body is present. The polyimide resin molded article according to any one of claims 4 and 5 , wherein a tensile elastic modulus measured at a tensile speed of 20 mm / min in accordance with JISK7161 is 3.5 GPa or more.