JP5477327B2 - Method for producing polyimide resin - Google Patents

Description

  The present invention relates to a polyimide resin and a method for producing the same, and further to an insulated wire using the polyimide resin.

  Polyimide has a rigid and strong molecular structure, and an imide bond has a strong intermolecular force, and therefore exhibits the highest level of thermal characteristics, mechanical characteristics, and chemical characteristics among polymer materials. Due to their attractive properties, polyimide resins are used in a variety of applications including insulating materials, substrate materials, coating materials, adhesives, aerospace materials, and the like.

  A product made of a polyimide resin is usually produced by imidization after forming into a desired shape (for example, a film shape or a coating film shape) using a varnish obtained by dissolving polyamic acid (polyamic acid) in an organic solvent. The imidization of the polyamic acid proceeds by heating (usually 200 to 500 ° C.) or a dehydration / imidation reaction with a catalyst and a dehydrating agent.

  When applying a varnish in which a polyamic acid is dissolved, it is important to adjust the concentration of the polyamic acid in the varnish and to adjust the viscosity of the varnish from the viewpoint of the stability of the coating thickness and the allowable viscosity of the coating apparatus. On the other hand, in a molded body produced from a polyamic acid varnish, defects such as bubbles and shape deformation may occur due to dehydration and volume shrinkage accompanying imidization. Thus, various proposals have been made to suppress the amount of dehydration and volume shrinkage associated with imidization by utilizing partially imidized partially imidized polyamic acid.

  For example, Patent Document 1 (Japanese Patent Publication No. 10-502869) discloses a method for forming a polyimide coating film using partially imidized partially imidized polyamic acid as follows. A first solution consisting of a diamine and dianhydride monomer and an organic solvent is prepared. These monomers are polymerized to prepare a polyamic acid that is soluble in the organic solvent. About 10 to 95% of the amic acid group of the polyamic acid is imidized in the organic solvent to prepare a partially imidized polyamic acid. The concentration of the polyamic acid solution is further increased and about 0.1 to about 10% by weight of a rocking agent is mixed to prepare the paste. A template is placed on the surface to be coated, and the paste is applied to the surface through the template. The solvent is evaporated and the partially imidized polyamic acid is completely imidized. According to Patent Document 1, by partially imidizing polyamic acid, it becomes easier to dissolve in an organic solvent, and a solution containing a large amount of solid content can be formed. Furthermore, if a solution can contain a large amount of solid content, it is said that it is possible to obtain a coating film with less shrinkage on the substrate.

  Patent Document 2 (JP-A-5-140306) discloses 1,4-bis (3-aminopropyl) tetramethyldisiloxane a mol% (1 ≦ a ≦ 30), 4,4′-oxydi Aniline b mol% (70 ≦ b ≦ 99), pyromellitic dianhydride c mol% (0 <c ≦ 105), 3,3 ′, 4,4′-benzophenone tetracarboxylic dianhydride d mol% ( 0 <d ≦ 105) [where 90 ≦ (a + b) ≦ 105, 90 ≦ (c + d) ≦ 105 and (c + d): (a + b) = 1.00 to 1.03] while stirring at 50 to 120 ° C. while stirring. Thus, a method for producing a polyamic acid composition in which an amidation polyaddition reaction and a dehydrating ring-closure imidization reaction are simultaneously performed and an imidation ratio of the polyaddition product is 10 to 30% is disclosed. According to Patent Document 2, by heating, partially ring-closing imidization in the synthesis of polyamic acid, and controlling the imidation rate to 10 to 30%, it has moderate solubility in aqueous alkali solution and stable viscosity during storage. It is said that a polyamic acid composition having high properties and excellent in film properties of the cured product, particularly excellent adhesion, can be obtained.

  Patent Document 3 (Japanese Patent Laid-Open No. 6-157753) describes partially imidized polyamic acid (x) having an imidization ratio of X% (0 ≦ X ≦ 50) as α wt% (1 ≦ α ≦ 99). Partially imidized polyamic acid composition obtained by mixing partially imidized polyamic acid (y) having an imidization ratio of Y% (0 <Y ≦ 50) with β wt% (1 ≦ β ≦ 99, α + β = 100) Is disclosed. According to Patent Document 3, any imidization ratio can be synthesized very easily by mixing partially imidized polyamic acids having different imidization ratios, and thereby a polyamic acid composition always having a constant etching rate. Can be provided.

Japanese National Patent Publication No. 10-502869 Japanese Patent Laid-Open No. 5-140306 JP-A-6-157753

  Recently, demands for miniaturization and high performance of electric and electronic parts are becoming more and more demanding, and demands for dimensional accuracy and defect suppression for polyimide resin moldings used for such electric and electronic parts are becoming stricter. . For example, as an electric wire for a coil of a motor or the like, an insulated wire (generally manufactured by applying and baking an insulating varnish on a metal conductor wire) in which an insulating coating is formed on the outer periphery of the metal conductor wire is widely used. However, from the viewpoint of miniaturization and high performance of the coil, there is a strong demand for the insulating coating to be thinner and more homogeneous while maintaining high bending characteristics and high corona discharge resistance. In order to meet such a demand for the polyimide resin molded body, it is very important to accurately control and adjust the imidization rate of the polyamic acid varnish.

  However, the partially imidized polyamic acid synthesized by the conventional method as described in Patent Documents 1 and 2 is difficult to accurately control the imidization rate in the synthesis reaction stage, and sampling measurement (for example, , FT-IR: Fourier transform infrared spectroscopy) and the like. On the other hand, although the method described in Patent Document 3 seems to be improved in terms of ease of adjustment, the synthesis itself of the two types of partially imidized polyamic acid to be mixed is a conventional method, and the control is There was a problem that the difficulty was not solved fundamentally.

Accordingly, an object of the present invention, in order to satisfy the above requirements, the imidization ratio is to provide a method for producing a polyimide resins consisting precisely controlled portion imidized polyamic acid.

This onset Ming, for achieving the above object has the following characteristics.
In the method for producing a polyimide resin according to the present invention, a process A in which an isocyanate component and an acid component composed of tetracarboxylic dianhydride are subjected to a synthetic reaction to produce an acid anhydride-terminated imide compound represented by the following chemical formula (1). And a step B in which a diamine component is synthesized and reacted with the acid anhydride-terminated imide compound to produce a partially imidized polyamic acid represented by the following chemical formula (2), and the chemical formula (2) obtained by the step B Or a partially imidized polyamic acid represented by the following chemical formula (3) and a partial imide represented by the above chemical formula (2), which is produced by a synthetic reaction of a diamine component and a tetracarboxylic dianhydride. A partially imidized polyamic acid represented by the following chemical formula (4) produced by copolymerization with a fluorinated polyamic acid. Te, thermal methods and / or methods of manufacturing a polyimide resin and a step E further partially imidized by chemical methods, (but the following chemical formula (1), in (2), R ₁ and R ₂ may be the same or different from each other a tetravalent organic group, X and R ₃ is a divalent organic group, n represents Ri 1 or more integer der the following chemical formula (3), ( In 4), R ₁ , R ₂ , R ₄ and R ₅ are tetravalent organic groups which may be the same or different from each other, and m is an integer of 1 or more .

According to the present invention can provide a method for producing a polyimide resins which imidization ratio consists precisely controlled portion imidized polyamic acid.

It is a cross-sectional schematic diagram which shows one example of the insulated wire which concerns on this invention.

  Embodiments according to the present invention will be described below. However, the present invention is not limited to the embodiment taken up here, and can be appropriately combined and improved without departing from the scope of the invention.

[Polyimide resin of the first embodiment]
As described above, the polyimide resin according to the first embodiment of the present invention is an acid represented by the following chemical formula (1) obtained by synthesizing an isocyanate component and an acid component composed of tetracarboxylic dianhydride. It consists of a partially imidized polyamic acid represented by the following chemical formula (2) obtained by synthesizing a diamine component with an anhydride terminal imide compound.

The present invention is characterized in that the synthesis of the polyamic acid is via the acid anhydride-terminated imide compound of the above chemical formula (1). The acid anhydride-terminated imide compound of the chemical formula (1) contains X, which is a divalent organic group, in its structure, and a ring-closed imide group is bonded to both ends. R ₁ and R ₂ which are tetravalent organic groups are bonded to each imide group.

As R ₁ and R _{2 in} the acid anhydride-terminated imide compound of the chemical formula (1), an organic group contained in tetracarboxylic dianhydride can be used. Examples of tetracarboxylic dianhydrides containing organic groups R ₁ and R ₂ include aromatic tetracarboxylic dianhydrides (eg, pyromellitic dianhydride (PMDA), 3,3 ′, 4,4 ′ -Benzophenone tetracarboxylic dianhydride (BTDA), 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic dianhydride (ODPA), 3, 3 ', 4,4'-biphenyltetracarboxylic dianhydride, 4,4'-(2,2-hexafluoroiropropylidene) diphthalic dianhydride, m-ter-phenyl-3,3 ', 4 , 4'-tetracarboxylic dianhydride, p-ter-phenyl-3,3 ', 4,4'-tetracarboxylic dianhydride) and alicyclic compounds (eg cyclobutane-1,2,3 , 4-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride and the like. The organic groups R ₁ and R ₂ may be the same as or different from each other. The organic group X will be described later.

In the present invention, a polyamic acid is obtained by synthesizing one or more diamines with the acid anhydride-terminated imide compound of the chemical formula (1). At this time, since the acid anhydride terminal imide compound of the chemical formula (1) already has an imide group in its molecular structure, a partially imidized polyamic acid can be obtained directly. In the partially imidized polyamic acid of the chemical formula (2), an amic acid is bonded to each of R ₁ and R ₂ in the acid anhydride-terminated imide compound of the chemical formula (1) as a repeating minimum unit. This amic acid has a structure polymerized through R ₃ which is a divalent organic group.

In the present invention, the "imidization ratio", the ratio of the number N _i of the imide groups to the sum of the number N _a number N _i and amic acid imide group in the minimum repeating units of the partial imidization of polyamic acid 100 N _i It is defined as / (N _i + N _a ) (unit:%). For example, the imidation ratio in the structure of chemical formula (2) is 50%. Note that n is an integer of 1 or more.

As the organic groups X and R ₃ , for example, organic groups represented by the following chemical formulas (5) to (10) can be used.

In the above chemical formulas (5) to (10), some of the hydrogen atoms on the aromatic ring are halogen elements (eg, fluorine, chlorine, bromine, etc.) or alkyl groups (eg, methyl, ethyl, propyl, butyl) Etc.), a halogen-substituted alkyl group (for example, a phenyl group, an alkoxy group, a trifluoromethyl group, a trichloromethyl group, a tribromomethyl group, etc.), a hydroxyl group, a nitro group or the like. R ₆ , R ₇ , and R ₈ are not particularly limited. For example, “-CH _2- ”, “-O-”, “-CO-”, “-S-”, “-SO _2- ” ”,“ —CO—O— ”,“ —CO—NH— ”,“ —C (CH ₃ ) ₂ — ”,“ —C (CF ₃ ) ₂ — ”and the like are preferably selected. Furthermore, since the partially imidized polyamic acid of the chemical formula (2) can be synthesized using a diamine containing R ₃ , a diamine skeleton other than those described above may be used as R ₃ , an aliphatic group or a chemical formula You may use the alicyclic compound which hydrogenated the aromatic ring of (5)-(10).

  The partially imidized polyamic acid of the chemical formula (2) has a structure in which only the bonding group bonded to the organic group X is imidized and the other amic acid sites are not imidized. As a result, a partially imidized polyamic acid having an imidization rate accurately controlled to 50% is obtained.

The conventional partially imidized polyimide resin includes, for example, a diamine containing an organic group X, a diamine containing an organic group R ₃ , a tetracarboxylic dianhydride containing an organic group R ₁ , and an organic group R ₂ . It is produced by subjecting a polyamic acid synthesized from tetracarboxylic dianhydride to a thermal or chemical partial imidization treatment. In this case, as shown in chemical formula (2), only the portion bonded to the organic group X does not have an imidized structure, and the whole is imidized at random, which makes it difficult to control the imidization rate. there were.

[Polyimide resin of the second embodiment]
The polyimide resin according to the second embodiment of the present invention has the following chemical formula (3) obtained by synthesizing a partially imidized polyamic acid represented by the chemical formula (2), a diamine component, and tetracarboxylic dianhydride. And a partially imidized polyamic acid represented by the following chemical formula (4) obtained by copolymerizing a polyamic acid represented by

The polyamic acid represented by the chemical formula (3) has a structure in which a tetracarboxylic dianhydride containing a tetravalent organic group R ₄ and a diamine compound containing a tetravalent organic group R ₅ are combined in a repeating minimum unit. Have. Examples of tetracarboxylic dianhydrides containing an organic group R ₄ include aromatic tetracarboxylic dianhydrides (eg, pyromellitic dianhydride (PMDA), 3,3 ′, 4,4′-benzophenone tetra Carboxylic dianhydride (BTDA), 3,3 ', 4,4'-diphenylsulfone tetracarboxylic dianhydride (DSDA), 4,4'-oxydiphthalic dianhydride (ODPA), 3,3', 4,4'-biphenyltetracarboxylic dianhydride, 4,4 '-(2,2-hexafluoroiropropylidene) diphthalic dianhydride, m-ter-phenyl-3,3', 4,4 ' -Tetracarboxylic dianhydride, p-ter-phenyl-3,3 ', 4,4'-tetracarboxylic dianhydride, etc.) and alicyclic compounds (eg cyclobutane-1,2,3,4- Tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, etc.). On the other hand, there is no particular limitation on the diamine compound containing the tetravalent organic group R ₅ . The organic groups R ₁ , R ₂ , R ₄ and R ₅ may be the same as or different from each other. M is an integer of 1 or more.

  As in the chemical formula (2), the partially imidized polyamic acid represented by the chemical formula (4) is imidized only in the bonding group bonded to the organic group X, and other amic acid containing the chemical formula (3). The site has a structure that is not imidized. Further, the imidization ratio within the repeating minimum unit containing the organic group X is 50%. From this, by controlling the copolymerization ratio of the chemical formula (2) and the chemical formula (3), the imidization ratio of the partially imidized polyamic acid of the chemical formula (4) can be arbitrarily set within the range of more than 0% and less than 50%. And can be controlled accurately.

Incidentally, conventional partially imidized polyimide resin, for example, a diamine containing organic group X, a diamine containing an organic group R _3, a diamine containing an organic group R _5, tetracarboxylic acid dianhydride containing an organic group R ₁ Thermal or chemical partial imidization treatment of polyamic acid synthesized from the product, tetracarboxylic dianhydride containing organic group R ₂ and tetracarboxylic dianhydride containing organic group R ₄ It is made by applying. In this case, as shown in chemical formula (4), only the portion bonded to the organic group X does not have an imidized structure, and the whole is imidized at random, which makes it difficult to control the imidization rate. there were.

[Insulated wire]
FIG. 1 is a schematic cross-sectional view showing an example of an insulated wire according to the present invention. As shown in FIG. 1, an insulated wire 10 according to the present invention is such that an insulating coating 2 made of the aforementioned polyimide resin is formed on the outer periphery of a metal conductor wire 1. Although there is no particular limitation in the manufacturing method of the insulated wire 10, the conventional method (For example, application | coating and baking of the insulating varnish on a metal conductor wire) can be utilized suitably.

  The metal conductor wire 1 is not particularly limited, and a gold wire, a silver wire, a superconducting wire, or the like can be used in addition to a copper wire and an aluminum wire used for a normal enameled wire. Moreover, the conductor which gave metal plating, such as nickel, to the outer periphery of a copper wire may be sufficient. Furthermore, the shape of the conductor covered with the insulating coating 2 according to the present invention is not particularly limited, and may be a round shape or a quadrilateral shape. The quadrilateral shape in the present invention includes a quadrangular shape with rounded corners and a rounded rectangular shape.

  In the insulated wire according to the present invention, a coating for improving the adhesion between the metal conductor wire 1 and the insulating coating 2 may be formed between the metal conductor wire 1 and the insulating coating 2. In addition, the insulated wire according to the present invention may form a coating for imparting lubricity or a coating for imparting scratch resistance to the outer periphery of the insulating coating 2. These additional coatings are not particularly limited, and known coatings can be used. The additional film may be formed by applying and baking an insulating varnish, or by extrusion using an extruder.

[Production method of polyimide resin]
(Synthesis of acid anhydride-terminated imide compound of chemical formula (1))
In the present invention, an acid anhydride-terminated imide compound represented by the chemical formula (1) is produced by a synthetic reaction between an isocyanate component and an acid component composed of tetracarboxylic dianhydride.

  Examples of the isocyanate component include aromatics such as 4,4′-diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), xylylene diisocyanate (XDI), biphenyl diisocyanate, diphenylsulfone diisocyanate, diphenyl ether diisocyanate, and the like. Group diisocyanates, isomers and multimers thereof. In addition, some of the hydrogen atoms on these aromatic rings are halogen elements (eg, fluorine, chlorine, bromine, etc.), alkyl groups (eg, methyl group, ethyl group, propyl group, butyl group), halogen-substituted alkyl groups. It may be substituted with a substituent such as a phenyl group, an alkoxy group, a trifluoromethyl group, a trichloromethyl group, or a tribromomethyl group, a hydroxyl group, or a nitro group. If necessary, use aliphatic diisocyanates (eg, hexamethylene diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, etc.), alicyclic diisocyanates hydrogenated with the above aromatic diisocyanates and isomers thereof. -You may use together. The acid component comprising tetracarboxylic dianhydride is as described above.

The above isocyanate component and a tetracarboxylic dianhydride containing a tetravalent organic group R ₁ or R ₂ are blended in a molar ratio of 1: 2. If necessary, the isocyanate component may be increased to a molar ratio of about 1.5: 2. When these are stirred and mixed in a solvent and heated in a nitrogen atmosphere, an imidization reaction occurs while generating carbon dioxide (CO ₂ ), and an acid anhydride-terminated imide compound of the chemical formula (1) is synthesized. As heating temperature, 60-160 degreeC is preferable and 80-140 degreeC is more preferable. Moreover, as heating time, 30 minutes-6 hours are preferable, and 1-3 hours are more preferable.

  In the above synthesis reaction, carbon dioxide is only generated by condensation, and thus there is an advantage that it is not particularly necessary to purify the obtained acid anhydride terminal imide compound. The obtained acid anhydride-terminated imide compound may contain an oligomer obtained by polymerizing diisocyanate and tetracarboxylic dianhydride, but the acid anhydride-terminated imide compound in the present invention is There is no problem even if a simple oligomer is included.

  In the present invention, the acid anhydride-terminated imide compound solution after the synthesis reaction can be used as a raw material solution for the next synthesis reaction (polyamic acid synthesis reaction) as it is. Therefore, the present invention has an advantage that the synthesis of the acid anhydride terminal imide compound and the synthesis of the polyamic acid can be performed in one pot (that is, the production is simple).

(Synthesis of polyamic acid of chemical formula (3))
A tetracarboxylic dianhydride containing a tetravalent organic group R ₄ and a diamine compound containing a tetravalent organic group R ₅ are polymerized to produce a polyamic acid of the formula (3). There is no particular limitation on the method of the reaction, and a conventional method can be used. However, in the present invention, it is important to synthesize a polyamic acid so as not to cause an imidization reaction. The synthesis of the polyamic acid represented by the chemical formula (3) may be performed separately from or simultaneously with the step of synthesizing the partially imidized polyamic acid.

(Synthesis of partially imidized polyamic acid represented by chemical formula (2) or chemical formula (4))
The acid anhydride-terminated imide compound represented by the chemical formula (1) obtained above is blended with a diamine containing a divalent organic group R ₃ and mixed with stirring in a solvent to cause a polymerization reaction, whereby the chemical formula (2 ) Of partially imidized polyamic acid. In addition, a polymerization reaction is performed by blending a diamine containing a divalent organic group R ₃ and a polyamic acid of the chemical formula (3) with an acid anhydride terminal imide compound of the chemical formula (1) and stirring and mixing in a solvent. Occurs, and a partially imidized polyamic acid of the chemical formula (4) is synthesized. Alternatively, a diamine containing a divalent organic group R ₃ , a diamine containing a tetravalent organic group R ₅ , and a tetrahydrate other than an acid anhydride terminal imide compound with respect to the acid anhydride terminal imide compound of the chemical formula (1) Carboxylic dianhydride (tetracarboxylic dianhydride containing a tetravalent organic group R ₄ ) is mixed and stirred in a solvent to cause a polymerization reaction, resulting in a partially imidized polyamic compound of formula (4) An acid is synthesized. Although there is no particular limitation on the solvent in the above synthesis reaction, for example, polar solvents such as N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), N, N-dimethylformamide (DMF) are preferably used. Can be used.

  The above polymerization reaction (synthesis of partially imidized polyamic acid) is desirably performed at a low temperature of about -40 to 40 ° C so that imidization reaction does not occur. More desirably, it is −10 to 30 ° C. By performing the polymerization reaction at a low temperature, imidation at a portion other than the imide group derived from the acid anhydride terminal imide compound of the chemical formula (1) is suppressed, and the imidization rate of the resulting partially imidized polyamic acid is accurately determined. Can be controlled. The imidization ratio of the partially imidized polyamic acid of the chemical formula (2) is 50%. Moreover, the imidation ratio of the partially imidized polyamic acid of the chemical formula (4) is 0% depending on the blending ratio of the acid anhydride terminal imide compound of the chemical formula (1) to be copolymerized and the polyamic acid of the chemical formula (3). It can be controlled with high accuracy within the range of less than 50%.

  The obtained partially imidized polyamic acid may be taken out and used as a powder by reprecipitation, or may be used in the form of a solution (varnish). Considering the ease of use of the partially imidized polyamic acid varnish (properties required for the polyamic acid varnish), it is preferable that the nonvolatile component is increased (the volatile component is decreased) and the viscosity is small.

  The partially imidized polyamic acid varnish decreases in viscosity as the imidization rate increases as compared to the case of 0% imidization rate, but the viscosity increases as the imidization rate increases beyond a certain region, Finally, the polyimide becomes insoluble. Therefore, the imidation ratio of the partially imidized polyamic acid is preferably 10 to 70%, and more preferably 25 to 50%.

  As described above, the partially imidized polyamic acid according to the present invention can accurately control the imidization rate in the range of more than 0% to 50%. An imidization ratio of more than 50% is achieved by further imidizing partially imidized polyamic acid of chemical formula (2) or chemical formula (4) by conventional thermal and / or chemical methods. Is possible. Although the partial imidization by the conventional method has a weak point in the controllability of the imidization rate, since the imidization rate of the partially imidized polyamic acid of the present invention as a base is accurate, the conventional partial imidization polyamic The imidation ratio can be adjusted more accurately than the acid.

(Polyimide resin made of partially imidized polyamic acid)
After forming into a desired shape using the partially imidized polyamic acid of the present invention, a polyimide resin molded product can be produced by complete imidization. For example, the partially imidized polyamic acid varnish of the present invention is applied on a base film by a spin coating method or a dip coating method, or applied to the outer periphery of a round or quadrilateral metal conductor wire, or a copper-clad laminate It can be applied on a plate (CCL) or cast into a substrate shape. Moreover, there is no special limitation in the use of the polyimide resin molding of this invention, It can replace and use the conventional polyimide resin, but generation | occurrence | production of defects, such as a shape deformation and a bubble, can be suppressed rather than before. effective.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example, this invention is not limited to these.

Example 1
4,4'-Diphenylmethane diisocyanate (MDI) 12.5 g as the isocyanate component and 4,4'-oxydiphthalic dianhydride (ODPA) 31.2 g as the tetracarboxylic dianhydride N-methyl-2- It was dissolved in 100 g of pyrrolidone (NMP) and reacted at 120 ° C. for 2 hours in a nitrogen atmosphere to prepare an acid anhydride-terminated imide compound solution. After the reaction solution was cooled to 30 ° C., 9.9 g of 4,4′-diaminodiphenylmethane (DDM) as a diamine component and 96.9 g of NMP solvent were added to the solution, and the reaction was performed at room temperature / nitrogen atmosphere for about 15 hours. (Overnight) was stirred and mixed to prepare the partially imidized polyamic acid varnish of Example 1.

  When the property of the obtained partially imidized polyamic acid varnish of Example 1 was investigated, the non-volatile component was 21.3% by mass. The imidation ratio measured from the peak of the imide group using FT-IR was 49%, which can be said to have sufficiently achieved 50% expected from the blending ratio.

(Example 2)
MDI (5.0 g) as the isocyanate component and 12.5 g (ODPA) as the tetracarboxylic dianhydride were dissolved in 100 g of NMP solvent and reacted at 120 ° C. for 2 hours in a nitrogen atmosphere to obtain an acid anhydride-terminated imide compound solution. Prepared. After the reaction solution was cooled to 30 ° C., 11.9 g of DDM as a diamine component and 60.4 g of NMP solvent were added to the solution and dissolved. After the diamine component is sufficiently dissolved, 12.5 g of ODPA is further added as an additional tetracarboxylic dianhydride, and stirring and mixing is performed for about 15 hours (overnight) in a room temperature / nitrogen atmosphere. An imidized polyamic acid varnish was prepared.

  When the property of the obtained partially imidized polyamic acid varnish of Example 2 was examined, the nonvolatile component was 20% by mass. The imidization rate measured from the peak of the imide group using FT-IR was 26%, which can be said to have sufficiently achieved the 25% expected from the compounding ratio.

  As described above, according to the present invention, a partially imidized polyamic acid having an imidization rate accurately controlled can be obtained. Thereby, the polyimide resin in which generation | occurrence | production of defects, such as a shape deformation and a bubble, was suppressed compared with the past, and its molded object (for example, insulated wire) can be provided.

  1 ... conductor, 2 ... insulating coating, 10 ... insulated wire.

Claims (1)

A method for producing a polyimide resin,
A step A in which an isocyanate component and an acid component composed of tetracarboxylic dianhydride are reacted to form an acid anhydride-terminated imide compound represented by the following chemical formula (1);
Step B for generating a partially imidized polyamic acid represented by the following chemical formula (2) by synthesizing a diamine component with the acid anhydride terminal imide compound;
The partially imidized polyamic acid represented by the chemical formula (2) obtained by the step B, or the polyamic acid represented by the following chemical formula (3) produced by a synthetic reaction of a diamine component and tetracarboxylic dianhydride. And a partially imidized polyamic acid represented by the following chemical formula (4) produced by copolymerizing the partially imidized polyamic acid represented by the chemical formula (2) with a thermal method and / or a chemical method. And a process E for partially imidizing the polyimide resin, wherein R ₁ and R ₂ are tetravalent organic groups in the following chemical formulas (1) and (2). may be the same or different, X and R ₃ is a divalent organic group, n represents Ri 1 or more integer der the following chemical formula (3), in (4), R _1, R _2, R ₄ And R ₅ may be the same or different from each other a tetravalent organic group, m is an integer of 1 or more).

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