JP7549724B2 - Polyimide manufacturing method - Google Patents

Description

The present invention relates to a method for producing polyimide using dimer diamine as a raw material.

In recent years, with the progress of miniaturization, weight saving, and space saving of electronic devices, there is an increasing demand for flexible printed circuits (FPCs) that are thin, lightweight, flexible, and have excellent durability even when repeatedly bent. Because FPCs allow three-dimensional and high-density mounting even in a limited space, their applications are expanding to include wiring for moving parts of electronic devices such as HDDs, DVDs, and smartphones, as well as components such as cables and connectors.

In addition, with the further advancement of high performance electronic devices, it is also necessary to support higher frequencies of transmitted signals. When transmitting high frequency signals, if there is a large transmission loss in the transmission path, inconveniences such as loss of electrical signals and longer signal delay times will occur. Therefore, in the future, it will be important to reduce transmission loss in FPCs as well. FPCs and adhesives that can support higher frequencies are required.

As a technique for an adhesive layer mainly composed of polyimide, it has been proposed to apply a crosslinked polyimide resin obtained by reacting a polyimide made from a diamine compound derived from an aliphatic diamine such as dimer acid (dimer fatty acid) with an amino compound having at least two primary amino groups as functional groups to the adhesive layer of a coverlay film (for example, Patent Document 1). It has also been proposed to apply a resin composition using such a polyimide in combination with a thermosetting resin such as an epoxy resin and a crosslinking agent to a copper-clad laminate (for example, Patent Document 2). However, Patent Documents 1 and 2 do not take into consideration the effects of by-products other than the dimer diamine derived from the dimer acid contained in the raw material.

Dimer acids are dimerized fatty acids obtained by the Diels-Alder reaction using natural fatty acids such as soybean oil fatty acids, tall oil fatty acids, rapeseed oil fatty acids, and the like, as well as oleic acid, linoleic acid, linolenic acid, erucic acid, and the like, which are refined from these, as raw materials. It is known that polybasic acid compounds derived from dimer acids are obtained as compositions of the raw fatty acids and trimerized or higher fatty acids (for example, Patent Document 3).

JP 2013-1730 A JP 2017-119361 A JP 2017-137375 A

As a means of controlling the physical properties of resins mainly composed of polyimide, it is important to control the molecular weight of the polyimide precursor, polyamic acid, or polyimide. However, when dimer diamine is used as a raw material, it is used in a state that contains by-products other than dimer diamine derived from dimer acid, making it difficult to control the molecular weight of the polyimide within a certain range.

The object of the present invention is therefore to provide a method for stably polymerizing polyimide with good properties using dimer diamine as a raw material.

As a result of intensive research, the inventors of the present invention have noticed that in the production of polyimide using a dimer diamine composition as a raw material, amine compounds other than dimer diamine affect the molecular weight of the polyimide, and have discovered that polyimide can be stably produced by controlling the amount of these amine compounds, thus completing the present invention.

That is, the present invention provides a method for producing a polyimide by reacting a tetracarboxylic anhydride component with a diamine component containing a dimer diamine composition mainly composed of a dimer diamine in which two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.
In the method for producing a polyimide of the present invention, the dimer diamine composition comprises the following components (a) to (c):
(a) dimer diamine;
(b) a monoamine compound obtained by substituting a terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group;
(c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the above-mentioned dimer diamine);
About
The content of the component (a) is 96% by weight or more based on the dimer diamine composition,
The dimer diamine composition is characterized in that the total area percentage of the components (b) and (c) is 4% or less in a chromatogram measured by gel permeation chromatography.

In the method for producing polyimide of the present invention, the area percentage of the chromatogram of the component (c) may be 3% or less.

In the method for producing a polyimide of the present invention, the ratio (b/c) of the area percentages of the chromatograms of the components (b) and (c) may be 1 or more, and in this case, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) may be 0.97 or more and less than 1.0.

In the method for producing a polyimide of the present invention, the ratio (b/c) of the area percentages of the chromatograms of the components (b) and (c) may be less than 1, and in this case, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) may be 0.97 or more and 1.1 or less.

In the method for producing a polyimide of the present invention, the weight average molecular weight of the polyimide may be in the range of 40,000 to 150,000.

The polyimide production method of the present invention controls the content of amine compounds other than dimer diamine in the dimer diamine composition, so that in the production of polyimide using the dimer diamine composition as a raw material, it is possible to suppress the variation in the weight average molecular weight of polyimide from lot to lot. As a result, polyimide with good properties can be stably produced, stabilizing the quality and improving the yield.

The embodiment of the present invention will be described in detail.

The method for producing polyimide of the present invention involves imidizing a precursor polyamic acid obtained by reacting a tetracarboxylic anhydride component with a diamine component containing a dimer diamine composition mainly composed of a dimer diamine in which the two terminal carboxylic acid groups of a dimer acid are substituted with primary aminomethyl groups or amino groups.

[Tetracarboxylic acid anhydride component]
Examples of the tetracarboxylic acid anhydride used in the polyimide according to the embodiment of the present invention include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, pyromellitic dianhydride, 1,4-phenylenebis(trimellitic acid monoester) dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic acid dianhydride, 4,4'-oxydiphthalic anhydride, 2,3',3,4'-biphenyltetracarboxylic acid dianhydride, 2,2',3,3'-, 2,3,3',4'- or 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride, 2,3',3,4'-diphenylethertetracarboxylic acid dianhydride, bis(2, 3-dicarboxyphenyl)ether dianhydride, 3,3'',4,4''-, 2,3,3'',4''- or 2,2'',3,3''-p-terphenyltetracarboxylic dianhydride, 2,2-bis(2,3- or 3,4-dicarboxyphenyl)-propane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)methane dianhydride, bis(2,3- or 3,4-dicarboxyphenyl)sulfone dianhydride, 1,1-bis(2,3- or 3,4-dicarboxyphenyl)ethane dianhydride, 1,2,7,8-, 1,2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthrenol Helical tetracarboxylic dianhydride, 2,2-bis(3,4-dicarboxyphenyl)tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 1,2,5,6-naphthalene tetracarboxylic dianhydride, 1,4,5,8-naphthalene tetracarboxylic dianhydride, 2,3,6,7-naphthalene tetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5,6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7-(or 1,4,5,8-)tetrachloronaphthalene-1, 4,5,8-(or 2,3,6,7-)tetracarboxylic dianhydride, 2,3,8,9-, 3,4,9,10-, 4,5,10,11- or 5,6,11,12-perylenetetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine-2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4,4'-bis(2,3-dicarboxyphenoxy)diphenylmethane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 4,4'- Examples of the acid dianhydride include (hexafluoroisopropylidene)diphthalic anhydride, p-phenylene bis(trimellitic acid monoester acid anhydride), ethylene glycol bis anhydrotrimellitate, etc. Among these, when 2,2',3,3'-, 2,3,3',4'-, or 3,3',4,4'-benzophenonetetracarboxylic dianhydride is used, the ketone group present in the molecular skeleton may react with the amino group of component (b) or (c) described below to form a C=N bond, and the effect of the present invention is easily exhibited.

[Dimer diamine composition]
The dimer diamine composition used in the method of the present invention contains the following component (a) with the amounts of components (b) and (c) being controlled.

(a) dimer diamine;
The dimer diamine of the component (a) means a diamine in which two terminal carboxylic acid groups (-COOH) of a dimer acid are replaced by primary aminomethyl groups (-CH ₂ -NH ₂ ) or amino groups (-NH ₂ ). Dimer acid is a known dibasic acid obtained by intermolecular polymerization of unsaturated fatty acids, and its industrial production process is almost standardized in the industry, and is obtained by dimerizing unsaturated fatty acids having 11 to 22 carbon atoms using a clay catalyst or the like. Industrially obtained dimer acid is mainly composed of a dibasic acid having 36 carbon atoms obtained by dimerizing unsaturated fatty acids having 18 carbon atoms, such as oleic acid, linoleic acid, and linolenic acid, but contains any amount of monomer acid (having 18 carbon atoms), trimer acid (having 54 carbon atoms), and other polymerized fatty acids having 20 to 54 carbon atoms depending on the degree of purification. In addition, although double bonds remain after the dimerization reaction, in the present invention, those which have been further subjected to a hydrogenation reaction to reduce the degree of unsaturation are also included in the dimer acid.

It is advisable to use a dimer diamine composition in which the dimer diamine content of component (a) has been increased to 96% by weight or more, preferably 97% by weight or more, and more preferably 98% by weight or more, by a purification method such as molecular distillation. By increasing the dimer diamine content of component (a) to 96% by weight or more, it is possible to suppress the broadening of the molecular weight distribution of the polyimide. If technically possible, it is best that all of the dimer diamine composition (100% by weight) is composed of component (a) dimer diamine.

(b) a monoamine compound obtained by substituting a terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group;
The monobasic acid compound having 10 to 40 carbon atoms is a mixture of a monobasic unsaturated fatty acid having 10 to 20 carbon atoms derived from the raw material of dimer acid, and a monobasic acid compound having 21 to 40 carbon atoms which is a by-product during the production of dimer acid. The monoamine compound is obtained by substituting the terminal carboxylic acid group of these monobasic acid compounds with a primary aminomethyl group or an amino group.

The monoamine compound of component (b) is a component that suppresses the increase in molecular weight of the polyimide. During polymerization of the polyamic acid or polyimide, the monofunctional amino group of the monoamine compound reacts with the terminal acid anhydride group of the polyamic acid or polyimide, thereby blocking the terminal acid anhydride group and suppressing the increase in molecular weight of the polyamic acid or polyimide.

(c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the above-mentioned dimer diamine);
The polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms is a polybasic acid compound mainly composed of a tribasic acid compound having 41 to 80 carbon atoms, which is a by-product during the production of dimer acid. It may also contain a polymerized fatty acid other than dimer acid having 41 to 80 carbon atoms. The amine compound is obtained by substituting the terminal carboxylic acid group of these polybasic acid compounds with a primary aminomethyl group or an amino group.

The amine compound (c) is a component that promotes an increase in the molecular weight of the polyimide. The tri- or higher functional amino group, the main component of which is a triamine derived from trimer acid, reacts with the terminal acid anhydride group of the polyamic acid or polyimide, rapidly increasing the molecular weight of the polyimide. In addition, amine compounds derived from polymerized fatty acids other than dimer acids having 41 to 80 carbon atoms also increase the molecular weight of the polyimide, causing the polyamic acid or polyimide to gel.

The above dimer diamine composition is quantified for each component by measurement using gel permeation chromatography (GPC). In order to facilitate confirmation of the peak start, peak top, and peak end of each component of the dimer diamine composition, a sample of the dimer diamine composition treated with acetic anhydride and pyridine is used, and cyclohexanone is used as an internal standard substance. Using the sample thus prepared, each component is quantified by the area percentage of the GPC chromatogram. The peak start and peak end of each component are taken as the minimum values of each peak curve, and the area percentage of the chromatogram is calculated based on this.

In addition, the dimer diamine composition has a total area percentage of components (b) and (c) of 4% or less, preferably less than 4%, in the chromatogram obtained by GPC measurement. By keeping the total area percentage of components (b) and (c) at 4% or less, it is possible to suppress the broadening of the molecular weight distribution of the polyimide.

The area percentage of the chromatogram of component (b) is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. By setting it in this range, it is possible to suppress a decrease in the molecular weight of the polyimide, and further to widen the range of the molar ratio of the tetracarboxylic anhydride component and the diamine component. Note that component (b) does not have to be included in the dimer diamine composition.

The area percentage of the chromatogram of component (c) is preferably 3% or less, more preferably 2% or less, and even more preferably 1% or less. By setting it in this range, a sudden increase in the molecular weight of the polyimide can be suppressed, and the range of the molar ratio of the tetracarboxylic anhydride component and the diamine component can be expanded. Note that component (c) does not have to be included in the dimer diamine composition.

In addition, when the ratio (b/c) of the area percentages of the chromatograms of components (b) and (c) is 1 or more, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) is preferably 0.97 or more and less than 1.0, and such a molar ratio makes it easier to control the molecular weight of the polyimide.

In addition, when the ratio (b/c) of the area percentages of the chromatograms of components (b) and (c) is less than 1, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) is preferably 0.97 or more and 1.1 or less, and such a molar ratio makes it easier to control the molecular weight of the polyimide.

The weight-average molecular weight of the polyimide is preferably within the range of 10,000 to 200,000, for example. If the weight-average molecular weight of the polyimide is within this range, it is easy to control the weight-average molecular weight of the polyimide. For example, when applied as an adhesive for FPCs, the weight-average molecular weight of the polyimide is more preferably within the range of 40,000 to 150,000. If the weight-average molecular weight of the polyimide is less than 40,000, the flow resistance tends to deteriorate. On the other hand, if the weight-average molecular weight of the polyimide exceeds 150,000, the viscosity increases excessively and the polyimide becomes insoluble in solvents, and defects such as uneven thickness of the adhesive layer and streaks tend to occur during the coating process.

The dimer diamine composition used in the present invention is preferably purified in order to reduce components other than dimer diamine. The purification method is not particularly limited, but known methods such as distillation and precipitation purification are suitable. The dimer diamine composition before purification is commercially available, for example, PRIAMINE 1073 (trade name), PRIAMINE 1074 (trade name), and PRIAMINE 1075 (trade name) manufactured by Croda Japan.

Diamine compounds other than dimer diamine used in polyimides include aromatic diamine compounds and aliphatic diamine compounds. Specific examples of these include 1,4-diaminobenzene (p-PDA; paraphenylenediamine), 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB), 2,2'-n-propyl-4,4'-diaminobiphenyl (m-NPB), 4-aminophenyl-4'-aminobenzoate (APAB), 2,2-bis-[4-(3-aminophenoxy)phenyl]propane, bis[4-(3-aminophenoxy)phenyl]sulfone, bis[4-(3-aminophenoxy)biphenyl, bis[1-(3-aminophenoxy)]biphenyl, bis[4-(3-aminophenoxy)phenyl]methane ... 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4,4'-methylene-2,6-diethylaniline, 3,3'-diaminodiphenylethane, 3,3'-diaminodiphenylethane, 3,3'-diaminodiphenyl, 3, 3'-Dimethoxybenzidine, 3,3''-diamino-p-terphenyl, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bisaniline, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bisaniline, bis(p-aminocyclohexyl)methane, bis(p-β-amino-t-butylphenyl)ether, bis(p-β-methyl-δ-aminopentyl)benzene, p-bis(2-methyl-4-aminopentyl)benzene, p-bis(1,1-dimethyl-5-aminopentyl)benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis(β-amino-t- butyl)toluene, 2,4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5-diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, piperazine, 2'-methoxy-4,4'-diaminobenzanilide, 4,4'-diaminobenzanilide, 1,3-bis[2-(4-aminophenyl)-2-propyl]benzene, 6-amino-2-(4-aminophenoxy)benzoxazole, 1,3-bis(3-aminophenoxy)benzene and other diamine compounds.

Polyimide can be produced by reacting the above tetracarboxylic dianhydride and diamine compound in a solvent to produce polyamic acid, which is then heated to close the ring. For example, the tetracarboxylic dianhydride and diamine compound are dissolved in an organic solvent in approximately equal molar amounts, and the mixture is stirred at a temperature in the range of 0 to 100°C for 30 minutes to 24 hours to polymerize, thereby obtaining polyamic acid, which is a precursor of polyimide. In the reaction, the reaction components are dissolved so that the precursor produced is in the range of 5 to 50% by weight, preferably 10 to 40% by weight, in the organic solvent. Examples of organic solvents used in the polymerization reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), 2-butanone, dimethylsulfoxide (DMSO), hexamethylphosphoramide, N-methylcaprolactam, dimethyl sulfate, cyclohexanone, dioxane, tetrahydrofuran, diglyme, triglyme, and cresol. Two or more of these solvents can be used in combination, and aromatic hydrocarbons such as xylene and toluene can also be used in combination. There are no particular limitations on the amount of organic solvent used, but it is preferable to adjust the amount used so that the concentration of the polyamic acid solution obtained by the polymerization reaction is about 5 to 50% by weight.

The synthesized polyamic acid is usually advantageously used as a reaction solvent solution, but it can be concentrated, diluted, or replaced with another organic solvent if necessary. Polyamic acid is also advantageously used because it generally has excellent solvent solubility. The viscosity of the polyamic acid solution is preferably within the range of 500 cps to 100,000 cps. If it is outside this range, defects such as uneven thickness and streaks are likely to occur in the film during coating operations using a coater, etc.

There are no particular limitations on the method for imidizing polyamic acid to form polyimide, and a suitable method is, for example, heat treatment in the solvent at a temperature in the range of 80 to 400°C for 1 to 24 hours. The temperature may be constant, or it may be changed during the process.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. In the following examples, various measurements and evaluations are as follows, unless otherwise specified.

[Method for measuring amine value]
Approximately 2 g of the dimer diamine composition is weighed into a 200-250 mL Erlenmeyer flask, and phenolphthalein is used as an indicator. A 0.1 mol/L ethanolic potassium hydroxide solution is added dropwise until the solution turns light pink, and the composition is dissolved in approximately 100 mL of neutralized butanol. 3-7 drops of phenolphthalein solution are added thereto, and titration is performed with 0.1 mol/L ethanolic potassium hydroxide solution while stirring until the sample solution turns light pink. Five drops of bromophenol blue solution are added thereto, and titration is performed with 0.2 mol/L hydrochloric acid/isopropanol solution while stirring until the sample solution turns yellow.
The amine value is calculated according to the following formula (1).
Amine value = {(V ₂ × C ₂ ) - (V ₁ × C ₁ )} × M _KOH / m (1)
Here, the amine value is a value expressed in mg-KOH/g, M _KOH is the molecular weight of potassium hydroxide, 56.1, V and C are the volume and concentration of the solution used in the titration, respectively, and the subscripts 1 and 2 represent a 0.1 M ethanolic potassium hydroxide solution and a 0.2 mol/L hydrochloric acid/isopropanol solution, respectively, and m is the sample weight expressed in grams.

[Measurement of weight average molecular weight (Mw) of polyimide]
The weight average molecular weight was measured by gel permeation chromatography (HLC-8220GPC, manufactured by Tosoh Corporation). Polystyrene was used as a standard substance, and tetrahydrofuran was used as a developing solvent.

[GPC and Chromatogram Area Percentage Calculation]
For GPC, 20 mg of the dimer diamine composition was pretreated with 200 μL of acetic anhydride, 200 μL of pyridine, and 2 mL of THF to prepare a 100 mg solution, which was then diluted with 10 mL of THF (containing 1000 ppm of cyclohexanone) to prepare a sample. The prepared sample was measured using a Tosoh Corporation product name: HLC-8220GPC under the following conditions: column: TSK-gel G2000HXL, G1000HXL, G1000HXL, flow rate: 1 mL/min, column (oven) temperature: 40° C., injection volume: 50 μL. Cyclohexanone was treated as a standard substance for the correction of the elution time.

In this case, the peak top of the cyclohexanone main peak was adjusted to a retention time of 27 to 31 minutes, and the period from the peak start to the peak end of the cyclohexanone main peak was 2 minutes, and the peak top of the main peak excluding the cyclohexanone peak was adjusted to a retention time of 18 to 19 minutes, and the period from the peak start to the peak end of the main peak excluding the cyclohexanone peak was adjusted to a retention time of 2 minutes to 4 minutes 30 seconds,
(a) Component represented by the main peak;
(b) A component represented by a GPC peak detected at a time later than the minimum retention time of the main peak;
(c) a component represented by a GPC peak detected at a time earlier than the minimum retention time of the main peak;
was detected.

The abbreviations used in the examples represent the following compounds: Incidentally, "%" for component b and component c means the area percentage of the chromatogram in GPC measurement.
BTDA: 3,3',4,4'-benzophenonetetracarboxylic dianhydride DDA1: product name: PRIAMINE 1075 manufactured by Croda Japan Co., Ltd., distilled and purified (component a: 97% by weight, component b: 0.4%, component c: 2.1%, amine value: 206 mg KOH/g)
DDA2: product name: PRIAMINE 1074, manufactured by Croda Japan Co., Ltd., distilled and purified (component a: 96% by weight, component b: 0%, component c: 3.6%, amine value: 210 mg KOH/g)
DDA3: product name: PRIAMINE 1074, manufactured by Croda Japan Co., Ltd., distilled and purified (component a: 96% by weight, component b: 0%, component c: 3.9%, amine value: 210 mg KOH/g)
DDA4: product name: PRIAMINE 1074, manufactured by Croda Japan Co., Ltd., distilled and purified (component a: 96% by weight, component b: 0%, component c: 3.7%, amine value: 208 mg KOH/g)
DDA5: product name: PRIAMINE 1075 manufactured by Croda Japan Co., Ltd., distilled and purified (component a: 97% by weight, component b: 2.8%, component c: 1.0%, amine value: 210 mg KOH/g)
NMP: N-methyl-2-pyrrolidone APB: 1,3-bis(3-aminophenoxy)benzene BAPP: 2,2-bis[4-(4-aminophenoxy)phenyl]propane 1,3-BAC: 1,3-bis(aminomethyl)cyclohexane BisDA: 4,4'-[propane-2,2-diylbis(1,4-phenyleneoxy)]diphthalic dianhydride (manufactured by SABIC Innovative Plastics Japan, LLC, product name: BisDA-1000)
The molecular weights of DDA1 to DDA5 were calculated according to the following formula (1).
Molecular weight = 56.1 × 2 × 1000 / amine value (1)

[Example 1]
A polyamic acid solution was prepared by charging 55.55 g of BTDA (0.17203 mol), 94.45 g of DDA1 (0.17342 mol), 210 g of NMP, and 140 g of xylene into a 1000 ml separable flask and thoroughly mixing for 1 hour at 40° C. This polyamic acid solution was heated to 190° C., heated and stirred for 4 hours, and 140 g of xylene was added to complete the imidization, preparing polyimide solution 1 (solid content: 30% by weight, weight average molecular weight: 84,800).

[Examples 2 to 19]
Polyimide solutions 2 to 19 were prepared in the same manner as in Example 1, except that the raw material compositions shown in Table 1 were used.

Examples of the production of polyimides with weight-average molecular weights in the range of 40,000 to 150,000 are shown in Examples 1 to 19.

In Examples 1, 4, 6, and 7 to 9, the acid anhydride/diamine ratio is 0.992. Here, a comparison of the weight average molecular weights of the polyimides in Examples 1 and 7 shows that component b is a component that suppresses an increase in the weight average molecular weight of the polyimide, or that component c is a component that promotes an increase in the weight average molecular weight of the polyimide, and a comparison of Examples 4 and 6 shows that component c is a component that promotes an increase in the weight average molecular weight of the polyimide.

From the results of Examples 7 to 9, it was confirmed that the variation in the weight average molecular weight of the polyimide between lots was small. Also, from the results of Examples 2, 3, and 5, it was confirmed that the weight average molecular weight of the polyimide could be suppressed to the range of 44,790 to 48,450 by setting the acid anhydride/diamine ratio to 1.008. Also, from the results of Examples 7, 10, and 11, it was confirmed that when the b component/c component is 1 or more, the weight average molecular weight of the polyimide could be increased from 67,820 to 108,880 by decreasing the acid anhydride/diamine ratio from 0.992 to 0.980. On the other hand, from the results of Examples 1, 2, and 12, it was confirmed that when the b component/c component is less than 1, the weight average molecular weight of the polyimide could be decreased from 84,800 to 40,520 by increasing the acid anhydride/diamine ratio from 0.992 to 1.020.

Examples 13 to 19 show examples in which a diamine other than the dimer diamine composition was used as the diamine component. From the results of Examples 13 to 15, it was confirmed that as the molar ratio of APB decreased, the proportion of component c in the dimer diamine composition increased, and the weight average molecular weight of the polyimide also increased. Furthermore, from the results of Examples 13 and 18, it was confirmed that the weight average molecular weight of the polyimide could be controlled to 43,300 by changing the acid anhydride/diamine ratio from 0.992 to 1.008. From the results of Examples 16 and 17, it was confirmed that the weight average molecular weight of the polyimide could be similarly controlled even if the diamine component other than the dimer diamine composition was changed. Furthermore, from the results of Examples 14 and 19, it was confirmed that the weight average molecular weight of the polyimide could be similarly controlled even if the acid anhydride/diamine ratio was changed.

Although the embodiment of the present invention has been described in detail above for the purpose of illustration, the present invention is not limited to the above embodiment.

Claims (4)

A method for producing a polyimide, comprising reacting a tetracarboxylic anhydride component with a diamine component containing a dimer diamine composition mainly composed of a dimer diamine obtained by substituting two terminal carboxylic acid groups of a dimer acid with primary aminomethyl groups or amino groups, the method comprising the steps of:
The tetracarboxylic acid anhydride component contains 3,3',4,4'-benzophenonetetracarboxylic acid dianhydride,
The molar ratio of the dimer diamine composition is 60 mol % or more based on the total diamine components,
The dimer diamine composition comprises the following components (a) to (c):
(a) dimer diamine;
(b) a monoamine compound obtained by substituting a terminal carboxylic acid group of a monobasic acid compound having 10 to 40 carbon atoms with a primary aminomethyl group or an amino group;
(c) Amine compounds obtained by substituting the terminal carboxylic acid group of a polybasic acid compound having a hydrocarbon group having 41 to 80 carbon atoms with a primary aminomethyl group or an amino group (excluding the above-mentioned dimer diamine);
About
The content of the component (a) is 96% by weight or more based on the dimer diamine composition,
When the ratio (b/c) of area percentages of the components (b) and (c) in a chromatogram obtained by measuring the dimer diamine composition using gel permeation chromatography is 1 or more, the weight average molecular weight of the polyimide is set in the range of 67,820 or more and 108,880 or less by setting the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) to 0.980 or more and 0.992 or less,
In this case, the total area percentage of the components (b) and (c) is 3.8% or less in the chromatogram,
When the ratio (b/c) is less than 1, the molar ratio of the tetracarboxylic anhydride component and the diamine component (tetracarboxylic anhydride component/diamine component) is set to 0.992 or more and 1.020 or less, thereby making the weight average molecular weight of the polyimide within the range of 40,520 or more and 84,800 or less,
In this case, the total area percentage of the components (b) and (c) in the chromatogram is 2.5% or less. The method for producing polyimide according to claim 1, characterized in that the area percentage of the chromatogram of component (c) is 3% or less. The method for producing polyimide according to claim 1, characterized in that the area percentage of the chromatogram of component (c) is 2% or less. The method for producing the polyimide according to any one of claims 1 to 3, comprising a step of purifying the raw material of the dimer diamine composition to obtain the dimer diamine composition.