JP2024005109A - Polyimide resin and method for producing polyimide resin composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a soluble polyimide resin that does not solidify even at room temperature and has a low glass transition temperature, and to provide a method for producing a polyimide resin composition with enhanced adhesion and hardness, as well as improved solvent resistance and storage stability.

SOLUTION: The present invention provides a method for producing a polyimide resin in which an acid anhydride and a diamine are reacted in a reaction solvent to prepare the polyimide. The diamine includes a dimer diamine, and the reaction solvent includes an ester solvent.

SELECTED DRAWING: None

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to a polyimide resin and a method for producing a polyimide resin composition.

Polyimide resin has traditionally been widely used mainly in the electrical and electronic fields due to its high elasticity and heat resistance, but in recent years it has been used as a component of insulating ink, taking advantage of the chemical stability of the polyimide bond itself. This is happening more and more.
When used as ink, solvent resistance and moisture resistance are often required. Further, inks that do not require heat resistance are often applied to adherends that do not have heat resistance, and the ink is often required to be dried at a temperature of about 150° C. or lower. To achieve this, it is possible to make drying easier by using solvent-soluble polyimide that can form a coating film only by volatilization of the solvent, by lowering the glass transition temperature and drying temperature of the polyimide resin, and by increasing the diffusion rate of the solvent inside the resin. things have been done.

In order to obtain a polyimide resin coating film with excellent solvent resistance and moisture resistance, petrochemical-based synthetic products such as saturated or unsaturated aliphatic diamine, decane diamine, and dodecane diamine are suitable as monomers constituting the polyimide resin. However, polyimide resins using aliphatic monomers with little branching are difficult to use as inks because there are few solvents in which the resin can be dissolved when used as inks.

The so-called dimer diamine, which is a modified unsaturated fatty acid dimer, has a very bulky branched structure, so it has high solubility in solvents, and after forming a coating film as an ink, it is durable against a wide range of solvents. This is the best choice.
However, during the production of polyimide resin using dimer diamine, the solubility of polyamic acid, which is a reaction intermediate, is low, so during the reaction at high concentrations, polyamic acid precipitates, causing the entire reaction solution to gel, resulting in poor fluidity. The problem was that it was lost. In particular, when an acid anhydride and a dimer diamine are simultaneously charged into a reaction vessel, gelation of the reaction solution by the polyamic acid becomes noticeable. This gelling state occurs when the reaction solution is heated to 120°C or higher and as imidization of the polyamic acid progresses, it redissolves and becomes a uniform dissolution state, but since the entire reaction proceeds in a non-uniform state, the polymerization reaction The subsequent viscosity is not constant. In addition, gelation occurs in the resin solution after the reaction over time, and this is not a stable manufacturing method.
As a solution to this problem, for example, as exemplified in Patent Document 1, an acid anhydride and a reaction solvent are first charged, heated while stirring, and then dimer diamine is gradually added to a reaction vessel. The dropping reaction method is an effective method for preventing reaction abnormalities.

However, from the viewpoint of solvent solubility, solvent-soluble polyimides use highly polar solvents such as n-methylpyrrolidone, dimethylformamide, and gamma-butyrolactone, so solvent-soluble polyimides containing dimer diamines do not gel at room temperature. There was an issue where it could become solidified or solidified.
In addition, printing using ink containing polyimide resin requires a thick film of cured polyimide resin, and the upper limit of the solid content of solvent-soluble polyimide resin alone is about 30 to 50%. Difficult to deal with. To address this issue, organic or inorganic fillers have been added, but as the storage time elapses, the fillers tend to settle or change in viscosity, making them unusable.

2020-203981

In view of the above, the problems to be solved by the present invention are a method for producing a soluble polyimide resin that does not solidify even at room temperature and has a low glass transition temperature, and a polyimide resin that has excellent adhesion and hardness, and has good solvent resistance and storage stability. An object of the present invention is to provide a method for producing a resin composition.

As a result of extensive research, the present inventor has discovered a method for producing a soluble polyimide resin that does not solidify even at room temperature by using an ester solvent, and a polyimide resin composition that has excellent adhesion and hardness, and has good solvent resistance and storage stability. It is possible to provide a method for manufacturing a product.

That is, the gist of the present invention is as follows.
[1] A method for producing polyimide by reacting an acid anhydride and a diamine in a reaction solvent, the method comprising:
the diamine includes a dimer diamine,
A method for producing a polyimide resin, characterized in that the reaction solvent contains an ester solvent.
[2] The production of the polyimide resin according to [1], which includes the step of dissolving the acid anhydride in the reaction solvent and dropping the diamine dropwise into the reaction solvent in which the acid anhydride is dissolved to perform an imide reaction. Method.
[3] The polyimide resin according to [1] or [2], which comprises performing a ring-closing reaction while maintaining the concentration of the polyamic acid formed by the imidization reaction at 5% by mass or less to obtain a polyamide. Production method.
[4] The polyimide resin according to any one of [1] or [2], wherein the diamine is blended in an amount of 0.95 to 1.05 molar equivalent per 1 molar equivalent of the acid anhydride. manufacturing method.
[5] The method for producing a polyimide resin according to any one of [1] or [2], wherein the ester solvent is a benzoic acid ester.
[6] A method for producing a polyimide resin composition, comprising:
Producing polyimide by the method described in either [1] or [2],
A method for producing a polyimide resin composition, comprising a step of mixing a filler having an average particle size of 0.3 to 1.0 μm into the polyimide resin.
[7] A method for producing a polyimide resin composition, comprising:
Producing polyimide by the method described in either [1] or [2],
A step of mixing a filler with an average particle size of 0.3 to 1.0 μm into the polyimide resin,
A method for producing a polyimide resin composition, wherein the filler is mixed in a proportion of 10 to 4000 parts by mass based on 100 parts by mass of solid content of the polyimide resin.
[8] A method for producing a cured polyimide resin, comprising:
Producing polyimide by the method described in either [1] or [2],
A step of mixing a filler with an average particle size of 0.3 to 1.0 μm into the polyimide resin,
The filler is mixed at a ratio of 10 to 4000 parts by mass with respect to 100 parts by mass of solid content of the polyimide resin to produce a polyimide resin composition,
A method for producing a cured polyimide resin product, which comprises heating and drying the polyimide resin composition at a temperature of 50 to 200°C.

According to the method for producing polyimide of the present invention, it is possible to keep the concentration of polyamic acid low and rapidly proceed with the dehydration imidization reaction, thereby polymerizing polyimide in a uniform reaction field. The polyimide resin solution obtained by this method has a low glass transition temperature and can maintain a uniform liquid state without becoming gelatinous even at room temperature. The composition obtained by adding the filler has excellent storage stability without sedimentation of the filler or change in viscosity over time.

The present invention is a method for producing polyimide by reacting an acid anhydride and a diamine in a reaction solvent, the diamine containing a dimer diamine, and the reaction solvent containing an ester solvent. This is a manufacturing method.

<Polyimide resin>
In the present invention, polyimide refers to a polymer having polyimide bonds as repeating units, and polyimide resin refers to a resin containing polyimide.

<Production method of polyimide resin>
In the method for producing a polyimide resin of the present invention, the production conditions are not particularly limited, but the reaction temperature is usually 150 to 210°C, preferably 160 to 200°C. Although it depends on the production amount, the dropwise reaction time is about 30 to 120 minutes, preferably about 60 to 90 minutes.

One embodiment of the present invention preferably includes a step of dissolving an acid anhydride in a reaction solvent and dropping a diamine into the reaction solvent in which the acid anhydride is dissolved to perform an imide reaction. By first adding the acid anhydride to a reaction solvent and gradually dropping the diamine, the ring-closing reaction is carried out while maintaining the concentration of the polyamic acid at 5% by mass or less, and the dehydration imidization reaction is rapidly proceeded to form the polyamic acid. can prevent gelation caused by

<Acid anhydride>
In the present invention, the acid anhydride is not particularly limited, but includes aliphatic tetracarboxylic acid anhydrides, aromatic carboxylic acid anhydrides, and the like. Acid anhydrides can be used alone or in combination of two or more.

Examples of the aliphatic tetracarboxylic anhydride include cyclic or acyclic aliphatic tetracarboxylic dianhydride. Cycloaliphatic tetracarboxylic dianhydride is a tetracarboxylic dianhydride having an alicyclic hydrocarbon structure, and specific examples include 1,2,4,5-cyclohexanetetracarboxylic dianhydride. Cycloalkanetetracarboxylic dianhydride such as (HPMDA), 1,2,3,4-cyclobutanetetracarboxylic dianhydride (CBDA), and 1,2,3,4-cyclopentanetetracarboxylic dianhydride , bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride, dicyclohexyl-3,3',4,4'-tetracarboxylic dianhydride (HBPDA) ) and their positional isomers. These can be used alone or in combination of two or more. Specific examples of the acyclic aliphatic tetracarboxylic dianhydride include 1,2,3,4-butanetetracarboxylic dianhydride and 1,2,3,4-pentanetetracarboxylic dianhydride. These can be used alone or in combination of two or more. Furthermore, a combination of a cycloaliphatic tetracarboxylic dianhydride and an acyclic aliphatic tetracarboxylic dianhydride may be used.

Examples of the aromatic carboxylic anhydride include non-fused polycyclic aromatic tetracarboxylic dianhydride, monocyclic aromatic tetracarboxylic dianhydride, and fused polycyclic aromatic tetracarboxylic dianhydride. can be mentioned. Examples of the non-fused polycyclic aromatic tetracarboxylic dianhydride include 4,4'-oxydiphthalic dianhydride (ODPA), 3,4-oxydiphthalic dianhydride (aODPA), 4,4'-( 4,4'-isopropylidenediphenoxy)diphthalic dianhydride (BPADA) 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic acid Dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride (sBPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride (aBPDA), 3,3' , 4,4'-diphenylsulfonetetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2-bis(2,3-dicarboxyphenyl)propane dianhydride Anhydride, 2,2-bis(3,4-dicarboxyphenoxyphenyl)propane dianhydride, 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), 1,2-bis(2 , 3-dicarboxyphenyl)ethane dianhydride, 1,1-bis(2,3-dicarboxyphenyl)ethane dianhydride, 1,2-bis(3,4-dicarboxyphenyl)ethane dianhydride, 1,1-bis(3,4-dicarboxyphenyl)ethane dianhydride, bis(3,4-dicarboxyphenyl)methane dianhydride, bis(2,3-dicarboxyphenyl)methane dianhydride, 4 , 4'-(p-phenylenedioxy)diphthalic dianhydride and 4,4'-(m-phenylenedioxy)diphthalic dianhydride. Examples of monocyclic aromatic tetracarboxylic dianhydrides include 1,2,4,5-benzenetetracarboxylic dianhydride (PMDA), and fused polycyclic aromatic tetracarboxylic dianhydrides. Examples of the dianhydride include 2,3,6,7-naphthalenetetracarboxylic dianhydride.

<Diamine>
In the present invention, diamine includes dimer diamine. The content of dimer diamine in the diamine is preferably 50 to 100% by mass from the viewpoint of flexibility, adhesiveness and solvent resistance, and from the viewpoint of facilitating solvent drying by suppressing the glass transition point. is 75-100 mass.

Dimer diamine is a cyclic or acyclic dimer acid obtained as a dimer of unsaturated fatty acids in which all carboxyl groups are substituted with primary amino groups, and various known ones can be used without particular limitation. Can be used.

A commercially available dimer diamine may be used. Commercial products of dimer diamine include Versamine 551 (manufactured by Cognix Japan Co., Ltd.), Versamine 552 (manufactured by Cognix Japan Co., Ltd.; hydrogenated product of Versamine 551), PRIAMINE 1075, and PRIAMINE 1074 (all manufactured by Croda Japan Co., Ltd.). (manufactured by).

In the present invention, the diamine can include diamines other than dimer diamine. Diamines other than dimer diamine are not particularly limited as long as they are bifunctional diamines, and examples include aromatic diamines and aliphatic diamines.

Specific examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, 2,4-toluenediamine, m-xylylenediamine, p-xylylenediamine, 1,5-diaminonaphthalene, 2,6-diamino Aromatic diamines having one aromatic ring such as naphthalene; 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3 '-Diamino diphenyl ether, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfone, 3,3'-diaminodiphenylsulfone, 1,4-bis(4-aminophenoxy)benzene, 1,3-bis (4-aminophenoxy)benzene, bis[4-(4-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)phenyl]sulfone, 2,2-bis[4-(4-aminophenoxy) phenyl]propane, 2,2-bis[4-(3-aminophenoxy)phenyl]propane, 2,2'-dimethylbenzidine, 2,2'-bis(trifluoromethyl)benzidine (TFMB), 4,4' -bis(4-aminophenoxy)biphenyl, 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(4-amino-3-methylphenyl)fluorene, 9,9-bis(4-amino- Examples include aromatic diamines having two or more aromatic rings, such as 3-chlorophenyl)fluorene and 9,9-bis(4-amino-3-fluorophenyl)fluorene. These can be used alone or in combination of two or more.

Specific examples of aliphatic diamines include acyclic aliphatic diamines such as hexamethylene diamine; 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, norbornanediamine, 4,4' - Cycloaliphatic diamines such as diaminodicyclohexylmethane and the like. These can be used alone or in combination of two or more.

The molar equivalent of diamine is 0.95 to 1.05, preferably 0.97 to 1.03 per molar equivalent of acid anhydride.

<Ester solvent>
The ester solvent refers to a solvent containing -COO-. In the present invention, the ester solvent is not particularly limited as long as it does not affect the reaction, but examples include lactic acid esters such as methyl lactate, ethyl lactate, and butyl lactate; ethyl acetate, n-butyl acetate, isobutyl acetate, and acetic acid. Acetate esters such as isopentyl; Butyrate esters such as isopropyl butyrate, ethyl butyrate, and butyl butyrate; Pyruvate esters such as methyl pyruvate, ethyl pyruvate, and propyl pyruvate; Benzoic acids such as methyl benzoate and ethyl benzoate Esters: Examples include acetoacetate esters such as methyl acetoacetate and ethyl acetoacetate. These can be used alone or in combination of two or more.

There are no particular restrictions on the dehydration solvent as long as it is an azeotrope with water, such as toluene or methylbenzene, and there is no need to add it as long as the reaction solvent is an azeotrope with water, such as benzoic acid ester. good.

The polyimide resin produced according to the present invention can be used as an ink as it is, but when it is made into an ink, it can be adjusted by adding additives according to the characteristics of the printing machine used. For example, to adjust the viscosity, it can be diluted with a general-purpose solvent such as an ester solvent, a naphthenic solvent, terpineol, ethyl acetate carbitol, cyclohexanone, ethyl acetate, or toluene.

The method for producing a polyimide resin composition of the present invention includes the steps of producing a polyimide resin by the above-described method for producing a polyimide resin, and mixing a filler into the obtained polyimide resin.

In the method for producing a polyimide resin composition of the present invention, a polyimide resin solution is produced by the above-mentioned method for producing a polyimide resin, and an inorganic resin is added to the obtained polyimide resin solution in order to adjust the thickness of the coating film and impart various properties. Or it includes a step of mixing an organic filler.

Any type of inorganic filler can be used, and silica, alumina, barium sulfate, calcium carbonate, etc. can be used if an insulating coating film is desired. When imparting thermal conductivity, alumina, boron nitride, aluminum nitride, magnesium oxide, graphite powder, silver powder, copper powder, etc. can be used. When imparting electrical conductivity, silver powder, copper powder, carbon black, indium-tin mixed oxide powder, etc. can be used.

Any organic filler can be used as long as it does not dissolve in the solvent used for the polymer solution. Examples include crosslinked acrylic particles, crosslinked styrene particles, melamine resin particles, polyethylene particles, and polyimide particles.

The filler is preferably spherical. From the viewpoint of long-term stability of the composition, the average particle size of the filler is preferably 0.3 to 1.0 um, more preferably 0.4 to 0.8 um. By using a filler having such a particle size, sedimentation and viscosity increase can be suppressed. Further, by mixing a spherical filler with an average particle size of 1.0 to 5.0 um, the increase in viscosity can be further suppressed. The fillers may be used alone or in combination of two or more. In addition, in this specification, the "average particle size" means the particle size at 50% cumulative volume (D50) obtained using a laser diffraction scattering particle size distribution measuring method.

The amount of the filler to be mixed is not particularly limited depending on the use of the polyimide resin composition, and can be adjusted as appropriate. You may do so. For example, when the filler is alumina, 50 to 500 parts by weight of alumina may be mixed with 100 parts by weight of the solid content of the polyimide resin.

The viscosity of the polyimide resin and its composition produced according to the present invention is not particularly limited and can be adjusted as appropriate depending on the intended use.・It is s. The viscosity of the polyimide resin can be adjusted by adjusting the molecular weight of the resin, and the viscosity of the resin composition can be adjusted by using a solvent or the like. Note that the viscosity refers to the viscosity measured at 25° C. using, for example, a viscometer such as a cone-plate viscometer.

Applications of the polyimide resin composition produced according to the present invention are not particularly limited, and include films, coating agents, protective films, electrical insulation materials in general, bearings, heat-resistant paints, heat-insulating shafts, heat-insulating trays, electronic parts, and automobile parts. It can be used in various fields such as , ink, etc. Further, depending on the application, it may include a step of adding a viscosity modifier, an antifoaming agent, a crosslinking agent, a pigment, a dye, a plasticizer, and an antioxidant.

The method for producing a cured polyimide resin product of the present invention includes producing a polyimide resin composition by the above method for producing a polyimide resin composition, and heating the obtained polyimide resin composition at 50 to 200 °C, preferably 50 to 180 °C. More preferably, it includes heating and drying at a temperature of 50 to 150°C. Since the polyimide resin produced according to the present invention can form a cured product at a relatively lower temperature than the polyimide resin produced by conventionally known methods, it is suitable as an ink that does not require heat resistance.

(Example 1)
449.73 g of methyl benzoate and 87.25 g of pyromellitic dianhydride were placed in a 1 L reactor equipped with a stirring blade, a water drain reflux pipe, a nitrogen inlet, and a dropping funnel, and after purging with nitrogen, without stirring. It was heated in an oil bath maintained at 185°C. 214.40 g of dimer diamine (P1075, manufactured by Croda Japan) was weighed into a dropping funnel. PMDA was dissolved in the inside of the reactor approximately 30 minutes after the start of heating, and a transparent solution state was formed. Dimer diamine was added dropwise into the reactor over a period of about 60 minutes. After reacting for 4 hours after the completion of the dropwise addition, the reaction liquid became a transparent brown viscous liquid with a solid content of 39.8% and a viscosity of 55000 mPa*s. Even when the temperature dropped to room temperature, the reaction solution remained almost transparent, and even after it was taken out, it remained uniform with no gelation.

(Comparative example 1)
449.73 g of n-methylpyrrolidone and 87.25 g of PMDA were charged into a 1 L reactor equipped with a stirring blade, a water drain reflux pipe, a nitrogen inlet, and a dropping funnel, and after purging with nitrogen, the reactor was maintained at 185°C without stirring. It was heated in an oil bath. 214.40 g of dimer diamine (P1075, manufactured by Croda Japan) was weighed into a dropping funnel. PMDA was dissolved in the inside of the reactor approximately 30 minutes after the start of heating, and a transparent solution state was formed. Dimer diamine was added dropwise into the reactor over a period of about 60 minutes. After reacting for 4 hours after the completion of the dropwise addition, the reaction solution became a transparent brown viscous liquid, but when the temperature dropped to room temperature, it became gel-like and finally solidified.

(Example 3) PMDA + Alumina 90 g of the polyimide resin obtained in Example 1 and 300 g of ASFP-40 (spherical alumina manufactured by Denka) were charged into a 0.3 L planetary mixer, and the mixture was kneaded for 1 hour under reduced pressure to form a filler. was dispersed. Thereafter, 90 g of polyimide resin and 20 g of hexyl benzoate were added, and stirring under reduced pressure was performed again for 30 minutes to obtain a polyimide resin composition with a viscosity of 72,000 mPa*s.

(Example 4) PMDA + acrylic filler 100 g of the resin solution of Example 1 and 90 g of cross-linked acrylic powder KMR-3TA (manufactured by Soken Kagaku) were placed in a 0.3 L planetary mixer, and the mixture was kneaded for 1 hour under reduced pressure to form the filler. was dispersed. Thereafter, 100 g of polyimide resin and 30 g of naphthenic solvent D-110 (manufactured by Ando Parachemy) were added, and stirring under reduced pressure was performed again for 30 minutes to obtain a polyimide resin composition with a viscosity of 70,000 mPa*s.

(Example 5) PMDA + Alumina 90 g of the resin solution of Example 1 and 300 g of ASFP-05S (average particle size: 0.55 um spherical alumina made by Denka) were charged into a 0.3 L planetary mixer, and mixed for 1 hour under reduced pressure. The filler was dispersed by melding. Thereafter, 90 g of polyimide resin and 20 g of hexyl benzoate were added, and the mixture was again stirred under reduced pressure for 30 minutes. Thereafter, hexyl benzoate was added to adjust the viscosity of the polyimide resin composition to 60,000 mPa*s.

(Example 6) MDA + Alumina 90 g of the resin solution of Example 1 and 300 g of ASFP-07S (average particle size: 0.8 um spherical alumina made by Denka) were charged into a 0.3 L planetary mixer, and mixed for 1 hour under reduced pressure. The filler was dispersed by melding. Thereafter, 90 g of the resin solution and 20 g of hexyl benzoate were added, and the mixture was again stirred under reduced pressure for 30 minutes. Thereafter, hexyl benzoate was added to adjust the viscosity of the polyimide resin composition to 60,000 mPa*s.

(Example 7) PMDA + Alumina 90 g of the resin solution of Example 1 and 300 g of DAW-01 (average particle size: 2 um spherical alumina made by Denka) were charged into a 0.3 L planetary mixer, and kneaded for 1 hour under reduced pressure. to disperse the filler. Thereafter, 90 g of the resin solution and 20 g of hexyl benzoate were added, and the mixture was again stirred under reduced pressure for 30 minutes. Thereafter, hexyl benzoate was added to adjust the viscosity of the polyimide resin composition to 60,000 mPa*s.

(Example 8) PMDA + Alumina In a 0.3 L planetary mixer, 100 g of the resin solution of Synthesis Example 1, 100 g of FB-3SDC (average particle size: 3 um spherical silica manufactured by Denka) and ASFP-07S (average particle size: 0.8 um) were added. 175 g of spherical alumina manufactured by Denka Co., Ltd.) was charged and kneaded for 1 hour under reduced pressure to disperse the filler. Thereafter, 100 g of the resin solution and 25 g of hexyl benzoate were added, and the mixture was again stirred under reduced pressure for 30 minutes. Thereafter, hexyl benzoate was added to adjust the viscosity of the polyimide resin composition to 60,000 mPa*s.

(Evaluation of adhesion of coating film)
The polyimide resin of Example 1 and the polyimide resin compositions of Examples 2 and 3 were applied with a squeegee onto a slide glass via a 100 μm spacer, and then dried in a hot air oven at 120° C. for 30 minutes, and then JIS K5600-5. A 1 mm grid Cellotape peeling test was conducted in accordance with 1-6 to evaluate the adhesion of the coating film. Table 1 shows the results of the adhesion evaluation.

(Pencil hardness evaluation of coating film)
The polyimide resin of Example 1 and the polyimide resin compositions of Examples 2 and 3 were applied with a squeegee onto a slide glass through a 100 μm spacer, and then dried in a hot air oven at 120°C for 30 minutes, and the pencil hardness was JIS. The pencil hardness of the coating film was evaluated according to K5600-5-4. Table 1 shows the results of pencil hardness evaluation.

(Solvent resistance evaluation of coating film)
Using a solvent used in the electrolyte of lithium ion batteries, the polyimide resin compositions of Example 1 and Examples 2 and 3 were applied onto the release film with a squeegee through a 200 μm spacer, and then heated at 120°C and 30°C. After drying the test piece for 1 minute, the test piece was cut into pieces 1 cm wide and 4 cm long, and the initial weight was accurately weighed. 1:1) and ethylene carbonate/dimethyl carbonate (EC/DMC) mixed solvent (mass ratio 3:7) for 24 hours at room temperature. Thereafter, the test piece was taken out from the solvent, the solvent on the surface of the test piece was thoroughly wiped off, and then the weight of the test piece was measured again. As for solvent resistance, the rate of change in mass was expressed as a percentage from the difference between the initial mass and the mass after immersion, and was taken as the swelling ratio. Table 1 shows the results of solvent resistance evaluation (swelling rate).

In all cases, the coating film had good adhesion to glass and was flexible. None of them swells in a mixed solvent of ethylene carbonate and propylene carbonate (EC/PC), but both have sufficiently good solvent resistance for practical use in a mixed solvent of ethylene carbonate and dimethyl carbonate (EC/DMC). It shows.

(Stability evaluation of polyimide resin composition)
Each of the polyimide resin compositions of Examples 4 to 7 was placed in a storage container and stored at room temperature, and changes in viscosity and sedimentation of the filler were confirmed. The viscosity was measured at a stage temperature of 25° C. and a rotation speed of 5 rpm, and sedimentation was confirmed by scraping the bottom of the container once in a straight line from the outside to the center with the tip of a spatula. The evaluation results of viscosity change are shown in Table 2, and the evaluation results of sedimentation are shown in Table 3.

A viscosity change of 30% or less is considered good, and it can be seen that in Example 4, the viscosity change was good up to 1 month, and no sedimentation was observed for 3 months or more.
It can be seen that in Example 5, the viscosity change was good for up to 3 months, and no sedimentation was observed for more than 3 months.
Regarding Example 6, good results were obtained regarding viscosity change for more than 3 months, but regarding sedimentation, sedimentation was observed in one week due to the large average particle size of 2 μm, and good results were not obtained. Ta.
Regarding Example 7, good results were obtained regarding the viscosity change over a period of 3 months or more, and results were obtained in which the viscosity change was smaller than that of the polyimide resin compositions of Examples 4 to 6. In addition, good results were obtained for up to 2 months even when large particles with an average particle size of 3 μm were included.

Claims (8)

A method for producing polyimide by reacting an acid anhydride and a diamine in a reaction solvent, the method comprising:
the diamine includes a dimer diamine,
A method for producing a polyimide resin, characterized in that the reaction solvent contains an ester solvent. The method for producing a polyimide resin according to claim 1, comprising the steps of dissolving the acid anhydride in the reaction solvent and dropping the diamine dropwise into the reaction solvent in which the acid anhydride is dissolved to perform an imide reaction. The method for producing a polyimide resin according to claim 1 or 2, comprising performing a ring-closing reaction while maintaining a concentration of the polyamic acid formed by the imidization reaction at 5% by mass or less to obtain a polyamide. The method for producing a polyimide resin according to claim 1 or 2, wherein the amount of the diamine is 0.95 to 1.05 molar equivalent per 1 molar equivalent of the acid anhydride. . The method for producing a polyimide resin according to claim 1, wherein the ester solvent is a benzoic acid ester. A method for producing a polyimide resin composition, comprising:
Producing polyimide by the method according to any one of claims 1 or 2,
A method for producing a polyimide resin composition, comprising a step of mixing a filler having an average particle size of 0.3 to 1.0 μm into the polyimide resin. A method for producing a polyimide resin composition, comprising:
Producing polyimide by the method according to any one of claims 1 or 2,
A step of mixing a filler with an average particle size of 0.3 to 1.0 μm into the polyimide resin,
A method for producing a polyimide resin composition, wherein the filler is mixed in a proportion of 10 to 4000 parts by mass based on 100 parts by mass of solid content of the polyimide resin. A method for producing a cured polyimide resin, the method comprising:
Producing polyimide by the method according to any one of claims 1 or 2,
A step of mixing a filler with an average particle size of 0.3 to 1.0 μm into the polyimide resin,
The filler is mixed at a ratio of 10 to 4000 parts by mass with respect to 100 parts by mass of solid content of the polyimide resin to produce a polyimide resin composition,
A method for producing a cured polyimide resin product, which comprises heating and drying the polyimide resin composition at a temperature of 50 to 200°C.