JP2003119284A - Method for producing polyimide resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a polyimide resin, which method can produce industrially advantageously a polyimide resin, which is of very high utility as electric and electronic materials, is excellent in thermal resistance and moldability, and is stable in quality. SOLUTION: The method for producing a polyimide resin comprises submitting a polyamic acid solution, which is prepared by subjecting a tetracarboxylic acid dianhydride and a diamine to a ring-opening polyaddition reaction in an organic polar solvent, thermally to an imide ring-closure reaction and removal of the by-produced condensed water, in a reactor equipped internally with a multiplate disc dryer.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyamic acid solution obtained by subjecting a tetracarboxylic dianhydride and a diamine to a ring-opening polyaddition reaction in an organic polar solvent, to thermally conduct an imide ring-closure reaction and to increase the molecular weight. The present invention relates to a method for producing a polyimide resin that can be efficiently performed in a short time.

[0002]

2. Description of the Related Art Polyimide resins are widely used in the fields of electric and electronic materials because of their high heat resistance, flame retardancy and excellent electric insulation. Specifically, it is used as a film for base materials of flexible printed wiring boards and heat-resistant adhesive tapes, and as a resin varnish for insulating films and protective films of semiconductors. However, the polyimide resin has high hygroscopicity and excellent heat resistance, but it is insoluble and infusible or has a very high melting point, so that it cannot be said to be a material that is easy to use in terms of moldability. Therefore, in recent years, various polyimide resins have been proposed which overcome these drawbacks, have low hygroscopicity, and are soluble in an organic solvent and have excellent heat resistance and molding processability.

Conventionally, as a method for producing a polyimide resin soluble in an organic solvent, a polyamic acid solution obtained by reacting a tetracarboxylic dianhydride and a diamine in an organic polar solvent by a known method is used under normal pressure. A solution thermal cyclization method in which an imide ring closure reaction and a high molecular weight are promoted while heating and distilling off condensed water by-produced by azeotropy with a hydrophobic solvent (for example, JP-A-5-33128 and JP-A-6-80777). (Publication number) is generally known. However, in the conventional solution thermal cyclization method, it is not possible to remove the condensed water by-produced by dehydration cyclization of the acid amide bond to the outside of the system in the initial stage of heating,
There is a risk that the polymerization activity of the polymer may be hindered by hydrolysis, and that the mechanical properties of the material may be deteriorated due to insufficient high molecular weight, resulting in poor quality. Furthermore, the time required for the process is long, which is very disadvantageous industrially.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve these problems in the prior art, and its purpose is to provide excellent heat resistance and molding processability, and stable quality. It is intended to provide a method for efficiently producing a polyimide resin in a short time, which is suitable for the field of electric / electronic materials.

[0005]

That is, according to the present invention, a polyamic acid solution obtained by subjecting a tetracarboxylic acid dianhydride and a diamine to a ring-opening polyaddition reaction in an organic polar solvent is equipped with a multi-plate type disc dryer. A method for producing a polyimide resin, which comprises thermally removing imide ring closure reaction and condensation water by-produced by using a reactor.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION As a polyimide resin to which the present invention is applied, an organic solvent-soluble polyimide resin obtained by thermally imide-cyclizing tetracarboxylic dianhydride and diamine in an organic polar solvent The tetracarboxylic acid dianhydride used here is preferably 4,4′-oxydiphthalic acid dianhydride, 3,3 ′, 4,4′-benzophenone tetracarboxylic acid dianhydride, 3,3 ′, 4. , 4 '
-Biphenyltetracarboxylic dianhydride, 3,3 ',
4,4'-diphenylsulfone tetracarboxylic dianhydride, pyromellitic dianhydride, etc. are mentioned, and they can be used singly or in combination of two or more.

As the diamine component used here, 1,3-bis (3-aminophenoxy) benzene,
2,2′-bis (4- (4-aminophenoxy) phenyl) propane, 2,5-dimethyl-p-phenylenediamine, 2,4-dimethyl-m-phenylenediamine,
Aromatic diamines such as 2,2′-bis (4-aminophenoxy) hexafluoropropane, α, ω-bis (3-
Examples thereof include diamine compounds having a polydimethylsiloxane structure such as aminopropyl) polydimethylsiloxane. These diamines can also be used alone or in combination of two or more.

Further, in order to control the molecular weight of the obtained polyimide resin, it is possible to carry out the reaction by adding a small amount of acid anhydride or aromatic amine as an end cap agent. Examples of acid anhydrides that are end-capping agents include phthalic anhydride, maleic anhydride, and nadic anhydride, and examples of aromatic amines include p-methylaniline, p-methoxyaniline, and p-phenoxyaniline. The addition amount of the acid anhydride or aromatic amine that is the end cap agent is preferably 5 mol% or less. When it exceeds 5 mol%, the molecular weight of the obtained polyimide resin is remarkably reduced, and problems occur in heat resistance and mechanical properties.

The equivalent ratio of the acid component and the amine component in the polycondensation reaction is an important factor that determines the molecular weight of the polyamic acid obtained. It is generally well known that there is a correlation between the molecular weight and the mechanical properties of polymers, and the higher the molecular weight, the better the mechanical properties. Therefore, in order to obtain a polyimide resin having practically excellent strength, it is necessary to have a high molecular weight to some extent. In the present invention, the equivalent ratio of the acid component and the amine component used is not particularly limited, but the equivalent ratio of the acidic component to the amine component is 0.90 to 1.06.
It is preferably in the range of. When it is less than 0.90, the molecular strength is low and the material becomes brittle, resulting in weak mechanical strength. Also,
If it exceeds 1.06, unreacted carboxylic acid may be decarboxylated during heating and cause gas generation and foaming, which is not preferable.

The reaction between the tetracarboxylic dianhydride and the diamine is carried out by a known method in an organic polar solvent. As the organic polar solvent, N, N-dimethylformamide,
Aprotic polar solvents such as N, N-dimethylacetamide, N-methyl-2-pyrrolidone, tetrahydrofuran, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, cyclohexanone, and 1,4-dioxane can be mentioned, and one or more types can be used. You may use it in combination. At this time, a non-polar solvent compatible with the aprotic polar solvent may be mixed and used. Aromatic hydrocarbons such as toluene, ethylbenzene, xylene, mesitylene, and solvent naphtha are often used. Regarding the proportion of the non-polar solvent in the mixed solvent, the solubility of the solvent is lowered, so long as the polyamic acid resin obtained by the reaction does not precipitate, it is arbitrarily set according to the resin properties such as agitator capacity and solution viscosity. can do.

The reaction between the tetracarboxylic dianhydride and the diamine is carried out by dissolving a well-dried diamine component in the aforementioned dehydrated and purified reaction solvent, and adding a ring-closing ratio of 98%, more preferably 99% or more to the well-dried tetraamine. Carboxylic dianhydride is added, and the reaction is allowed to proceed for 2 to 10 hours at a temperature of 40 ° C or lower, more preferably 30 ° C or lower. At this time, the concentrations of both the tetracarboxylic dianhydride and the diamine components in the solvent can be appropriately selected, but they are 10 to 30% by weight.
It is appropriate to set the degree. If the concentration is less than 10% by weight, the product yield is reduced and it is not economical, and if it exceeds 30% by weight, not only does the solution viscosity increase and the load on the stirrer increases, but uniform reaction cannot be performed. There is.

The polyamic acid solution thus obtained is
Transferred to a reactor equipped with a multi-plate type disk dryer,
The imide ring-closure reaction and the increase in molecular weight are thermally performed while efficiently removing the condensed water generated as a by-product. At this time, it is preferable to add a hydrophobic solvent for distilling condensed water azeotropically in advance to the polyamic acid solution supplied to the reactor equipped with the multi-plate type disk dryer. As a hydrophobic solvent for azeotropically distilling off water, dichlorobenzene is generally well known, but for electronics use, chlorine components may be mixed, and preferably toluene, ethylbenzene, xylene, mesitylene. , The above aromatic hydrocarbons such as solvent naphtha are used. The addition amount can be arbitrarily set as long as it does not cause precipitation of the polyamic acid and the polyimide resin obtained by dehydration ring closure of the polyamic acid. If a hydrophobic solvent is not added, the condensation water produced as a byproduct of the dehydration ring closure reaction cannot be sufficiently distilled off from the reaction solution, and the acid amide bond may cause hydrolysis, which hinders the imide ring closure reaction. In addition, the polymerization activity may be lowered and the mechanical properties of the resulting polyimide resin may be adversely affected.

The reactor equipped with the multi-plate type disk dryer used in the present invention is more preferably equipped with a separator for separating and removing only the condensed water from the azeotrope of the generated condensed water and the hydrophobic solvent. If the reactor equipped with the multi-plate type disk dryer does not have a separator, the reaction liquid in the system becomes highly concentrated and highly viscous as the treatment progresses, not only increasing the load on the pumps but also the process piping. There is a risk that the scale will adhere to the inner wall and block it, or that the scale will be deposited on the surface of the disk, which is the heat exchange surface, and the heat transfer efficiency of the device will be reduced.

Further, the reactor equipped with the multi-plate type disk dryer used in the present invention preferably has a casing capable of maintaining a reduced pressure atmosphere in the system and a vacuum suction means. When the above-mentioned polyamic acid solution is treated using a reactor equipped with a multi-plate type disk dryer, the imide ring-closing reaction and the removal of condensed water generated are performed.
By performing the treatment under reduced pressure, the efficiency of removing the condensed water can be dramatically improved. Pressure in the reactor is 35k
It is preferable to control to a reduced pressure state of Pa to 95 kPa. When the pressure is less than 35 kPa, the boiling point of the solvent is significantly lowered and the liquid temperature does not rise, so that a practical reaction rate cannot be obtained, and when it exceeds 95 kPa, the temperature under normal pressure (atmospheric pressure) No significant advantage over treatment can be found.

The above-mentioned polyamic acid solution synthesized in a known reactor is transferred to a reactor equipped with a multi-plate type disc dryer used in the present invention, and then circulated on a disc surface which has been preheated. Spray through the supply line. The polyamic acid solution brought into contact with the disk surface causes an imide ring closure reaction, and the generated condensed water is rapidly removed from the system by azeotroping with a hydrophobic solvent. The heat transfer area and the number of disks used at this time are not particularly limited, and can be arbitrarily selected in accordance with the capacity of the polyamic acid as the object to be treated and the amount of condensed water generated so that the evaporation efficiency becomes the best. .

Regarding the specific operating conditions of the multi-plate type disk dryer, the heat transfer surface temperature of the disk surface is from 80 ° C to
It is preferable to set in the range of 250 ° C. Temperature is 80
If it is less than ℃, it is difficult to obtain a practical reaction rate.
If the temperature exceeds 50 ° C., deposition of scale on the disk surface, coloring of the resin, side reaction, etc. occur, which is not preferable in any case.

The rotation speed of the disk is 2 rpm to 5 rpm.
It is preferable to operate in the range of 0 rpm. If the rotation speed is less than 2 rpm, the residence time of the reaction solution on the disk surface is too long, which may cause scale adhesion. At a rotation speed of more than 50 rpm, the contact time with the reaction solution is too short. Not only the imide ring-closure reaction cannot be sufficiently performed, but even removal of condensed water becomes difficult, which affects the quality of the polyimide resin such as hydrolysis and deterioration of polymerization activity.

A commercially available product may be used as the multi-plate type disk dryer incorporated in the reactor used in the present invention, and examples thereof include a CD dryer manufactured by Nishimura Iron Works Co., Ltd.

Further, the production method of the present invention will be described in detail with reference to the equipment and flow schematic diagram of FIG. 1 and the cross-sectional view of the reactor incorporating the multi-plate type disk dryer of FIG. Tetracarboxylic dianhydride and diamine are reacted in reactor 1 (1) to obtain a polyamic acid solution. Then, the obtained polyamic acid solution is supplied to the mixing circulation tank (4) of the reactor 2 (3) equipped with the multi-plate type disk dryer by the transfer pump (2). Thereafter, the polyamic acid solution was sprayed from the tip of the supply nozzle (6) onto the heat transfer surface of the hollow disk (7) by the circulation supply pump (5), and the polyamic acid solution that did not adhere to the disk was mixed in the circulation tank (4). To fall. At this time, the hollow rotating disk (7) is attached to the column (8).
A rotary shaft (10) of a rotatable cylindrical structure supported by a bearing (9) fixed on a beam passed between the tops of the is used as a central axis to be rotationally driven by an electric motor (10). In addition, heating steam is circulated in the hollow disk (7) and the rotating shaft (10) in advance through the steam inlet (12) and the drain outlet (13) and adjusted to a predetermined temperature. The polyamic acid solution sprayed onto the disk surface is heated on the heat transfer surface to cause an imide ring closure reaction to generate condensed water. The generated condensed water and the hydrophobic solvent in the polyamic acid solution azeotrope on the disk surface, and become vapor in the evaporation tank (14). The generated vapor, which is an azeotrope of the hydrophobic solvent and condensed water, is cooled and liquefied in the condenser (16) through the vapor pipe (15) and then stored in the separator (18) through the condensate pipe (17). It The condensate stored in the separator (18) is separated into a hydrophobic solvent and condensed water into upper and lower layers due to the difference in specific gravity, and only the condensed water is extracted from the discharge port (19), and the hydrophobic solvent is collected in a pipe (20). To the reactor 2 (3). When the treatment is performed under reduced pressure, the pressure inside the system of the reactor 2 (3) is reduced by the vacuum pump (21). The above steps are repeated until the generation of condensed water can no longer be confirmed to complete the reaction and obtain a polyimide resin solution.

The polyimide resin solution obtained in the present invention can be diluted with a solvent or the like and used as it is as a coating varnish. Further, this solution may be put into a poor solvent to reprecipitate and precipitate a polyimide resin to remove unreacted monomers, dried and solidified, and then dissolved in an organic solvent again to be used as a purified product. In particular, in applications where impurities and foreign matters are a problem, it is preferable to dissolve it again in an organic solvent to obtain a filtration / purification varnish.

[0021]

EXAMPLES The present invention will be described in detail below with reference to examples and comparative examples. In each example, APB is 1,3-bis (3-aminophenoxy) benzene, BAPP is 2,2′-bis (4- (4-aminophenoxy) phenyl) propane, and 25DPX is 2,5-. Dimethyl-p-
Phenylenediamine, 24DPX is 2,4-dimethyl-m-phenylenediamine, APPS is α, ω-bis (3-aminopropyl) polydimethylsiloxane, O
DPA is 4,4'-oxydiphthalic dianhydride, BP
DA is 3,3 ', 4,4'-benzophenone tetracarboxylic dianhydride, BTDA is 3,3', 4,4'-biphenyltetracarboxylic dianhydride, and PMDA is pyromellitic dianhydride. It is an abbreviation. Moreover, the measuring method of the physical property in each example is as follows.

(Weight average molecular weight) A column (TSKgel α-M: 2) manufactured by Tosoh Corporation was used, and the flow rate was 1.0 m.
1 / min, eluent: N-methyl-2-pyrrolidone solution containing 0.01 mol / L lithium bromide, using a RI detector under analysis conditions of a column temperature of 40 ° C., using monodisperse polystyrene as a standard substance. Was measured by gel permeation chromatography (hereinafter abbreviated as GPC).

(Example 1) N-methyl-2-pyrrolidone 3 dehydrated and refined in a 100 L reactor equipped with a dry nitrogen gas inlet tube, a heat exchanger, a heating / cooling device and a stirring device.
Add 9.00 kg and stir vigorously for 10 minutes while flowing nitrogen gas. Next, APB4.893kg, BAPP
1.963 kg and 2.012 kg of APPS (average molecular weight of amine equivalent 840.36) were added and the system was cooled to 6
Heat to 0 ° C and stir until uniform. After being uniformly dissolved, the system was cooled to 20 ° C., and 6.679 kg of ODPA and 0.704 kg of BPDA were added over 15 minutes. After stirring for 3 hours while maintaining the temperature of the reactor at 20 ° C., 3.70 kg of toluene as a hydrophobic solvent and 6.0 of xylene were used as a hydrophobic solvent.
5 kg was added and mixed into the system to obtain a polyamic acid solution.

Thereafter, the polyamic acid solution was heated to a heat transfer area of 0.
The mixture was transferred to a reactor equipped with a multi-plate type disc dryer having three 2 m ² discs, and the temperature of the reactor was raised to 180 ° C. to carry out the imidization reaction while the treatment with the disc dryer was carried out. At this time, the hollow disk is 800 kPa
It was preheated with the steam and was processed at a rotation speed of 15 rpm. The time required until generation of condensed water from the system could not be confirmed was 150 minutes, and 62.0 kg of a polyimide resin solution was obtained. The weight average molecular weight of the polyimide resin measured by GPC was 100200.

(Example 2) The diamine component was replaced by BAPP7.
549 kg, 25 DPX 0.147 kg, APPS1.
820 kg (average molecular weight of amine equivalent 840.3
6), the acid anhydride component is BPDA 2.548 kg, BTD
A 4.185kg, hydrophobic solvent xylene 3.50k
g and mesitylene was changed to 6.25 kg to obtain a polyamic acid solution in the same manner as in Example 1. Then, the polyamic acid solution was transferred to a reactor equipped with a multi-plate type disc dryer having four discs having a heat transfer area of 0.2 m ² , and the temperature of the reactor was raised to 180 ° C while the treatment with the disc dryer was performed. Then, the imidization reaction was performed. At this time, the hollow disk was preheated with steam of 750 kPa and treated at a rotation speed of 10 rpm.
It took 120 minutes until the generation of condensed water could not be confirmed from the system, and the polyimide resin solution was 62.5 k.
g was obtained. The weight average molecular weight of the polyimide resin measured by GPC was 119200.

Example 3 A diamine component was added to APB5.9.
45 kg, APPS 2.139 kg (average molecular weight of amine equivalent 840.36), 25 DPX 0.346 k
g, acid anhydride component PMDA 0.166 kg, ODPA
A polyamic acid solution was obtained in the same manner as in Example 1 except that 7.653 kg and the hydrophobic solvent was changed to 9.75 kg of mesylene. After that, the polyamic acid solution was heated to a heat transfer area of 0.
Transfer to a reactor equipped with a multi-plate type disc dryer having 4 discs of 2 m ² and raise the temperature of the reactor to 170 ° C. while performing treatment with the disc dryer.
The imidization reaction was performed under a reduced pressure of kPa. At this time, the hollow disk was preheated with steam of 800 kPa and treated at a rotation speed of 20 rpm. The time required until the generation of condensed water cannot be confirmed from the system is 1
It took 15 minutes, and 61.5 kg of a polyimide resin solution was obtained. The weight average molecular weight of the polyimide resin measured by GPC was 109,800.

(Example 4) A diamine component was added to APB5.0
68 kg, APPS 2.083 kg (average molecular weight of amine equivalent 840.36), BAPP 1.016 kg,
24DPX 0.337kg, acid anhydride component ODPA
A polyamic acid solution was obtained in the same manner as in Example 1 except that 6.149 kg, BTDA 1.597 kg, the hydrophobic solvent was changed to toluene 4.50 kg, and xylene 5.25 kg. After that, heat transfer area of the polyamic acid solution 0.2 m
^It was transferred to a reactor equipped with a multi-plate type disk dryer having 4 disks of ² , and the temperature of the reactor was raised to 175 ° C while performing the treatment with the disk dryer, and 55 kP
The imidation reaction was carried out under the reduced pressure normal condition of a. At this time, the hollow disk was preheated with steam of 750 kPa and treated at a rotation speed of 12 rpm. It took 11 hours until the generation of condensed water could not be confirmed from the system.
It took 5 minutes, and 62.5 kg of a polyimide resin solution was obtained. The weight average molecular weight of the polyimide resin measured by GPC was 99600.

Comparative Example 1 A polyamic acid solution was obtained in the same manner as in Example 1. After that, the reactor was heated to 180 ° C. without performing the treatment with the multi-plate type disk dryer, and the imidization reaction was performed while distilling the generated condensed water out of the system,
61.0 kg of a polyimide resin solution was obtained. The time required until generation of condensed water from the system was not observed was 380 minutes. The weight average molecular weight of the polyimide resin measured by GPC was 74200.

Comparative Example 2 A polyamic acid solution was obtained in the same manner as in Example 2. After that, the reactor was heated to 180 ° C. without performing the treatment with the multi-plate type disk dryer, and the imidization reaction was performed while distilling the generated condensed water out of the system,
60.5 kg of a polyimide resin solution was obtained. The time required until generation of condensed water from the system was not observed was 365 minutes. The weight average molecular weight of the polyimide resin measured by GPC was 68200.

Comparative Example 3 A polyamic acid solution was obtained in the same manner as in Example 3. After that, the reactor was heated to 170 ° C. without performing the treatment with the multi-plate type disk dryer, and the imidization reaction was performed while distilling the generated condensed water out of the system,
61.0 kg of a polyimide resin solution was obtained. The time required until generation of condensed water from the system was not observed was 400 minutes. The weight average molecular weight of the polyimide resin measured by GPC was 66300.

Comparative Example 4 A polyamic acid solution was obtained in the same manner as in Example 4. Then, the reactor was heated to 175 ° C. without treatment with a multi-plate type disk dryer, and the imidization reaction was carried out for 12 hours without removing the generated condensed water to the outside of the system to obtain 64.0 kg of a polyimide resin solution. Obtained. Also G
The weight average molecular weight of the polyimide resin measured by PC is 13
It was 100.

[0032]

According to the method of the present invention, a polyamic acid solution obtained by subjecting a tetracarboxylic dianhydride and a diamine to a ring-opening polyaddition reaction in an organic polar solvent is used as a reactor equipped with a multi-plate type disc dryer. The polyimide resin can be efficiently obtained in a short time by the simple equipment and operation of performing heat treatment with, removing the condensation water produced as a by-product, and performing an imide ring-closure reaction. This is suitable as an industrial method for producing a polyimide resin, since quality fluctuation factors such as decomposition and deterioration of polymerization activity are eliminated.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the equipment and flow of the present invention.

FIG. 2 is a sectional view of a reactor equipped with a multi-plate type disk dryer.

[Explanation of symbols]

1 reactor 1 2 Transfer pump 3 reactor 2 4 circulating mixing tank 5 Circulation supply pump 6 supply nozzles 7 hollow disc 8 props 9 bearings 10 rotation axis 11 electric motor 12 Steam inlet 13 Steam outlet 14 evaporation tank 15 vapor piping 16 condenser 17 Condensate piping 18 separator 19 outlet 20 Recovery pipe 21 vacuum pump

Claims (4)

[Claims] 1. A polyamic acid solution obtained by subjecting a tetracarboxylic dianhydride and a diamine to ring-opening polyaddition reaction in an organic polar solvent is thermally treated using a reactor equipped with a multi-plate type disk dryer. A method for producing a polyimide resin, which comprises performing an imide ring-closing reaction and removing condensation water produced as a by-product. 2. The method for producing a polyimide resin according to claim 1, wherein the treatment in a reactor equipped with a multi-plate type disk dryer is performed under a reduced pressure condition of 35 kPa to 95 kPa. 3. When the treatment is carried out in a reactor equipped with a multi-plate type disk dryer, the condensed water by-produced by the imide ring closure reaction is distilled off azeotropically with a hydrophobic solvent. 1. The method for producing a polyimide resin according to 1 or 2. 4. A reactor equipped with a multi-plate type disk dryer is equipped with a separator for separating and removing condensed water distilled off azeotropically with a hydrophobic solvent. 4. The method for producing a polyimide resin according to any one of 3 to 3.