JP3377092B2 - Biphenyltetracarboxylic acid heat anhydride product - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to biphenyltetracarboxylic dianhydride obtained by dehydrating biphenyltetracarboxylic acid.

[0002]

It is well known that an aromatic polyimide having excellent properties as a heat resistant resin can be industrially advantageously produced by using biphenyltetracarboxylic dianhydride as a raw material. That is, an aromatic polyimide is generally obtained by cyclizing (imidizing) a polyamic acid obtained by polymerization (copolymerization) between biphenyltetracarboxylic dianhydride and an aromatic diamine at a low temperature near room temperature. ing. The biphenyl tetracarboxylic dianhydride is dimerized with an o-phthalic acid diester such as o-dimethyl phthalate using a palladium-based catalyst,
It can be obtained by preparing a biphenyltetracarboxylic acid through steps such as purification, crystallization, and hydrolysis, and then heating the biphenyltetracarboxylic acid to a high temperature for anhydrification.

For heating the above biphenyltetracarboxylic acid to a high temperature for dehydration, for example, 100 to 50 under normal pressure to 40 mmHg under reduced pressure in a nitrogen atmosphere.
The method of heating to 0 ° C is disclosed in Japanese Examined Patent Publication No. S57-15098.
It is described in Japanese Patent Publication No.

As a method for purifying biphenyltetracarboxylic dianhydride, a method for purifying crude biphenyltetracarboxylic dianhydride by heating it to volatilize it and recovering it is disclosed in JP-A-61-249977. Have been described.

A method for obtaining biphenyltetracarboxylic dianhydride with little coloring by heating biphenyltetracarboxylic acid in an acetic anhydride solvent at a low concentration for dehydration is disclosed in JP-A-62-116572. It is described in Japanese Patent Publication No.

JP-A-60-81154 discloses that an aromatic polyimide molding is hydrolyzed under specific alkaline conditions and heating conditions so that the concentration of decarboxylation components is 0.011 to 0.018%. BPTA (3, 3 ', 4,
4′-biphenyltetracarboxylic acid: “BPDA” in Examples 2 and 3 is a mistaken description of “BPTA”). But those 3,3 ', 4,4'
There is no disclosure of what purity 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride can be obtained by heating dehydration of biphenyltetracarboxylic acid.

[0007]

According to the study of the present inventor, when an aromatic polyamic acid is produced by copolymerizing biphenyltetracarboxylic dianhydride obtained by a known method with an aromatic diamine. It has been found that there is a problem that the viscosity of the polymerization reaction liquid is not sufficiently high and a high molecular weight aromatic polyamic acid cannot be obtained.

The object of the present invention is therefore to provide a biphenyltetracarboxylic dianhydride which makes it possible to produce high molecular weight aromatic polyamic acids (and also aromatic polyimides).

[0009]

MEANS FOR SOLVING THE PROBLEMS The present inventors have conducted a polymerization reaction in producing an aromatic polyamic acid by polymerizing a biphenyltetracarboxylic dianhydride obtained by a known method and an aromatic diamine. The reason why the viscosity of the liquid is not sufficiently high was examined. As a result, when the amount of biphenyltricarboxylic acids (biphenyltricarboxylic acid and / or its anhydride) mixed as impurities in biphenyltetracarboxylic dianhydride (reaction product) increases, the viscosity of the polymerization reaction liquid increases. Has been found to be hindered, that is, the formation of high molecular weight polyamic acids has been hindered.

Therefore, the present inventor has conducted extensive research on a method for obtaining a product containing a biphenyltetracarboxylic dianhydride having a low content (mixed amount) of biphenyltricarboxylic acids, and as a result, the biphenyltetracarboxylic acid was heated under a specific heating condition. It was found that a product (crystal) containing less than 0.15% by weight of the mixed biphenyltricarboxylic acids (mixed amount) can be obtained by dehydration under the following conditions, and thus, the biphenyltricarboxylic acid is extremely diminished. The inventors have found that a high molecular weight aromatic polyacic acid can be obtained by using as a raw material biphenyltetracarboxylic dianhydride in which the amount of acids mixed is reduced, and have completed the present invention.

[0011] The present invention is, of biphenyl tetracarboxylic acid
Biphenyl teto obtained by heat treatment of crystals
Lacarboxylic acid heat-anhydride product, said heat treatment
The average heating rate from at least 80 ° C to 250 ° C
Temperature does not exceed 50 ° C / hour, and then
Heating at a temperature of 250-300 ° C for at least 3 hours
With biphenyl tricarboxylic acid and / or
Is a biphenyltetracarboxylic acid heat-anhydride product characterized in that the content of the anhydride is less than 0.15% by weight with respect to the biphenyltetracarboxylic dianhydride. . The heating and dehydration of biphenyltetracarboxylic acid in the production of the heated and heated product of biphenyltetracarboxylic acid of the present invention is preferably carried out in the absence of a solvent, under an inert gas atmosphere, and under stirring.

The high-purity biphenyltetracarboxylic dianhydride in which the total content of the biphenyltricarboxylic acid and its anhydride is extremely small is obtained by preparing the crystal of the biphenyltetracarboxylic acid in an inert gas atmosphere (usually (At a pressure or under reduced pressure), when heat-treating at a dehydration temperature of 250 ° C. or higher to produce biphenyltetracarboxylic dianhydride, before raising the temperature from 80 ° C. to the dehydration temperature. The heat treatment is performed at an average heating rate of 50 ° C /
No longer than the time to remove adhering water and water of crystallization adhering to the crystals, followed by heating the preheated crystals at an anhydration temperature of 250-300 ° C. for at least 3 hours. It can be easily produced by treatment and dehydration.

In the above-mentioned manufacturing method, the pre-heating treatment heat-treats the crystals to 130 ° C. so that the average temperature rising rate does not become higher than 30 ° C./hour, and the crystals mainly adsorbed water. In the first step of removing, and the average heating rate is not higher than 50 ° C / hour,
It is preferable to include a second step of heating the crystal to raise the temperature from 130 ° C. to the dehydration temperature to remove mainly water of crystallization from the crystal.

The biphenyltetracarboxylic dianhydride of the present invention in which the content of biphenyltricarboxylic acids is extremely small is a crude biphenyltetracarboxylic dianhydride obtained by dehydrating a known biphenyltetracarboxylic acid or by a known method thereof. It cannot be obtained by industrial purification methods for anhydrides. For example, the above-mentioned JP-A-61-24
9977 and the method disclosed in JP-A-62-116
The mixed amount (content) of biphenyl tricarboxylic acids in the biphenyl tetracarboxylic dianhydride obtained by the method described in Japanese Patent No. 572 is usually 0.5% by weight or more.

The high-purity biphenyltetracarboxylic dianhydride (high-purity crystal) of the present invention can be produced as follows. Biphenyltetracarboxylic acid crystals, which is a raw material for a product containing high-purity biphenyltetracarboxylic dianhydride, is obtained by dimerizing an o-phthalic acid di-lower alkyl ester such as o-dimethyl phthalate and then hydrolyzing this. Can be obtained by Biphenyltetracarboxylic acid obtained by dimerization of o-phthalic acid di-lower alkyl ester is usually 3,3 ′, 4,4′-
Body, 2,2 ', 3,3'-body, and 2,3,3',
It is a mixture of three 4'-isomers, and the above-mentioned biphenyltetracarboxylic acid crystal is preferably one obtained by separating and purifying any one of these three species from the other two species. Among them, biphenyl tetracarboxylic acid is 3,
The 3 ', 4,4'-form is desirable.

In the method for producing high-purity biphenyltetracarboxylic dianhydride, when the above-mentioned dehydration heat treatment is performed, first, the pre-heat treatment during the heating from about 80 ° C. to the dehydration temperature is carried out on average. In order to prevent the temperature rising rate from becoming higher than 50 ° C./hour, preferably the average temperature rising rate is 45 ° C./hour or less for at least 1 hour to remove the adhering water and the crystal water adhering to the crystals. From room temperature to 8
The heating conditions for raising the temperature to 0 ° C. are not particularly limited. However, the above preheating treatment is particularly preferably at an average heating rate of about 0.01 to 28 ° C./hour, for at least 0.5 hours, particularly preferably so that the average heating rate does not become higher than 30 ° C./hour. For 1 to 5 hours, the crystal is heated to a temperature of about 130 ° C., the first step of removing and drying the crystal mainly by evaporation of adhering water, and the average heating rate of 50 ° C. / Particularly preferably, the average heating rate is 10 to 45 ° C so that the temperature does not become higher than the time.
/ Hour, at least 0.5 hours, particularly preferably 1 to
Heat the dried crystals as described above for 6 hours,
A pretreatment for dehydrating the crystals with good reproducibility is performed by a two-step process of heating the crystals from about 130 ° C. to the dehydration temperature and removing the water of crystallization from the crystals. desirable.

That is, when the first step of the preheating treatment is performed on the crystals, the adhering water retained or adsorbed in the voids between the crystal grains is evaporated by evaporation at about 80 to 130 ° C. Drying of the crystals occurs that is gradually removed. Further subsequently, when the above-mentioned second step is performed on the dried crystal, it is coordinated in the crystal at about 130 to the dehydration temperature or due to an intermolecular force between the crystal and water molecule. The water of crystallization that is bound is gradually removed from the crystals, so the removal of water that hinders dehydration
Dried well.

If the preheat treatment for heating the biphenyltetracarboxylic acid from about 80 ° C. to the dehydration temperature is carried out at an average temperature rising rate higher than 50 ° C./hour, removal and drying of the adhering water and crystallization water will be insufficient. Therefore, it becomes difficult to maintain the dehydration temperature uniformly throughout the crystal when the crystal is subjected to the dehydration heat treatment, which is not preferable. When the dehydration temperature cannot be maintained uniform, the entire crystal is unevenly heated, the temperature becomes extremely high locally, and the crystal sinters. In addition, the dehydration itself is not uniformly performed, and further, biphenyl tricarboxylic acid is likely to be produced by decarboxylation.

In the second step of the pre-heating treatment, the first half is heated to about 130 ° C to 170 ° C and the average heating rate is about 40 ° C.
/ Hour or less for at least 0.5 hours, and the latter half from about 170 ° C to the dehydration temperature is an average heating rate of 50 ° C.
It is also possible to carry out in stages, such as less than / hour or less.

In the dehydration step, the preheated crystals are stirred, if necessary, under an atmosphere of an inert gas (preferably nitrogen gas) in the absence of an active gas such as oxygen, Under normal pressure or reduced pressure, preferably under reduced pressure of normal pressure to 40 mmHg, and further 3) 250 to 300.
It is carried out by heating at a dehydration temperature of [deg.] C., preferably 255 to 290 [deg.] C., for at least 3 hours, preferably 5 to 40 hours, particularly preferably 10 to 30 hours.

In the above method, the crystals of biphenyltetracarboxylic acid, from which water has been sufficiently removed by the preheat treatment, are subjected to the dehydration heat treatment as described above, whereby a pair of adjacent carboxyl groups of the biphenyltetracarboxylic acid are heated. Each one water molecule is dehydrated from the group to undergo condensation to form the anhydrous ring of the carboxyl group, resulting in the production of biphenyltetracarboxylic dianhydride. In addition, biphenyl tricarboxylic acids (eg, 3,3 ′, 4-biphenyl tricarboxylic acid, 3,4,4′-biphenyl tricarboxylic acid, or acid anhydrides thereof) produced as a by-product in the dehydration step are sublimated. Are removed from the crystals of biphenyltetracarboxylic dianhydride.

In carrying out the above-mentioned production method, pressurized steam or a heat medium is circulated as a heat source in the jacket covering the voids in the rotating blades of the stirring device or the outer wall of the reaction vessel to produce biphenyltetracarboxylic acid. The crystals of may be subjected to pre-heating treatment and dehydration heating treatment, for example,
When the pressurized steam and the heat-resistant heat medium are used in combination, it is preferable to use different heat sources for the inside of the jacket and the space inside the rotary blade. The preheat treatment is preferably performed using pressurized steam, and for example, the pressurized steam used in the first preheat treatment has a steam pressure of 1.0 to 5
kg / cm ^2, it is preferred that particularly 1.1~3kg / cm ^2. The dehydration treatment is, for example, liquid or vapor of an aromatic compound such as alkylbenzene, alkylnaphthalene, alkyldiphenyl, diphenylether, hydrogenated triphenyl, dibenzyltoluene, or liquid of mineral oil such as paraffinic mineral oil or alkylaromatic mineral oil. It is preferable to use a heat resistant heat medium consisting of

When the heat treatment for pre-heating the crystal and the heat treatment for dehydration are carried out by using the same heat-resistant heat medium having different temperatures, the temperature can be continuously raised and stepwise for each heat treatment step. It can also be carried out separately in different places provided in the reaction vessel (for example, the gap of the rotating blades of the stirring device, the jacket covering the outer wall of the reaction vessel, etc.) each time the type of heat medium changes. Need not be supplied to. The heat source may be electric energy such as an electric resistance heater or an infrared heater, as long as it can uniformly heat each heat treatment and control the rate of temperature rise.

The above-obtained biphenyltetracarboxylic dianhydride has a content (mixed amount) of biphenyltricarboxylic acids of less than 0.15% by weight (product basis), and further conditions for dehydration treatment are selected. By doing this, 0.
It is less than 1% by weight.

The high-purity biphenyltetracarboxylic dianhydride having a small amount of mixed biphenyltricarboxylic acid of the present invention can be used as a raw material to produce a high-molecular-weight aromatic polyamic acid. That is, when such a high-purity biphenyltetracarboxylic dianhydride and an aromatic diamine are copolymerized by a known method, the viscosity of the polymerization reaction liquid increases and a high molecular weight aromatic polyamic acid is produced.

The viscosity of the polymerization reaction solution is usually represented by logarithmic viscosity. The logarithmic viscosity is a value represented by the following formula, and has a high correlation with the molecular weight of polyamic acid (and polyimide).

[0027]

[Equation 1]

The logarithmic viscosity (measurement temperature) is obtained by copolymerizing the biphenyltetracarboxylic dianhydride having a reduced content of biphenyltetracarboxylic acid produced as described above and an aromatic diamine by a known method. ; 3
0 ° C., concentration; 0.5 g (polymer) / 100 mL solvent,
Solvent: N-methyl-2-pyrrolidone) is 2.5 to 7.0
It is possible to obtain a high molecular weight polyamic acid in the range of 3.0 to 5.0.

[0029]

[Example 1] A disk-type agitator having a rotary blade of a horizontal rotary shaft having a void formed therein for allowing pressurized steam or a heat-resistant heat medium to flow therein is incorporated, and pressurized steam or Reaction tank (dryer) whose outer wall is almost covered with a jacket for circulating a heat-resistant heat medium
280 kg of purified 3,3 ′, 4,4′-biphenyltetracarboxylic acid crystals were added to the above, and the first step of the pre-heating treatment was performed with a rotary blade while stirring under a nitrogen gas atmosphere at normal pressure. 2kg / c for both jacket and jacket
m ² G of pressurized steam was circulated, and the temperature was raised from 80 ° C. to 100 ° C. at an average heating rate of 30 ° C./hour in order to remove the water adhering to the crystals. I kept it for a while.

Subsequently, the second step of the pre-heating treatment is switched so that a pressure steam of 6 kg / cm ² G is passed between the rotary vane and the jacket to remove the crystal water of the crystal. Then, the temperature is raised from 100 ° C. to 130 ° C. at an average heating rate of 25 ° C./hour, and then 130 ° C.
For 2 hours. Then, the reaction mixture was heated to 280 ° C. under the condition of an average temperature increase of 35 ° C./hour. Then, the preheated crystals in the reaction vessel were maintained at a dehydration temperature of 280 ° C. for 20 hours while stirring under an atmosphere of nitrogen gas to obtain 3,3 ′, 4,4′-biphenyltetracarboxylic acid. The acid was dehydrated to produce 247 kg of 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride.

Next, 3 equipped with a stirrer and a nitrogen flow pipe
In a 00 ml three-necked flask, 11.76 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride obtained as described above and diaminodiphenyl ether 8.
00g and N-methyl-2-pyrrolidone 177.8
4 g was charged, and the viscosity of the polymerization reaction liquid when the aromatic polyamic acid was synthesized was measured by stirring at 30 ° C. for 5.5 hours under a nitrogen atmosphere, and the logarithmic viscosity was calculated from the above formula. Table 1 shows the results of the dehydration and the logarithmic viscosity of the polymerization reaction solution.

[Example 2] A heat-resistant heat medium having various temperatures was circulated in a jacket of a reaction tank, and no other heat source was used. The first step of the pre-heat treatment was performed by raising the temperature from about 80 ° C. to 100 ° C. at an average heating rate of 25 ° C./hour and then maintaining the temperature at 100 ° C. for 1 hour. continue,
In the second step (first half) of the preheat treatment for removing water of crystallization of crystals, the temperature was raised from 100 ° C. to 150 ° C. at an average heating rate of 25 ° C./hour, and then maintained at 150 ° C. for 2 hours. I did it. Furthermore, the second step of the pre-heat treatment (second half)
The temperature was raised from 150 ° C. to the dehydration temperature of 280 ° C. at an average heating rate of 35 ° C./hour. Thereafter, Example 1 was repeated except that the dehydration treatment was carried out by maintaining the temperature at 280 ° C. for 20 hours.
The same reaction tank and raw material as those used in Example 1 were used to carry out the dehydration reaction under the same reaction conditions as in Example 1,
The 3 ', 4,4'-biphenyltetracarboxylic acid was dehydrated to produce 247 kg of 3,3', 4,4'-biphenyltetracarboxylic dianhydride.

Next, using this 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, an aromatic polyamic acid was synthesized in the same manner as in Example 1 to obtain the logarithmic viscosity of the polymerization reaction solution. Was calculated. Table 1 shows the results of the dehydration and the logarithmic viscosity of the polymerization reaction solution.

[Example 3] With respect to the crystals in the reaction vessel, the first step of the pre-heat treatment was carried out by raising the temperature from about 80 ° C to 130 ° C continuously with a heat resistant heat medium at 20 to 25 ° C.
The temperature is raised at an average heating rate of 1 hour / hour, and then the second step of the pre-heating treatment is performed by raising the temperature from 130 ° C. to 280 ° C. continuously by a heat resistant heat medium at 30 to 35 ° C./hour. Example 1 was carried out using the same reaction vessel and raw materials as used in Example 1, except that the heating was performed at an average heating rate, and finally, the crystals were maintained at 280 ° C. for 20 hours to carry out dehydration heat treatment.
The dehydration reaction is performed under the same reaction conditions as in 3,
The 3 ', 4,4'-biphenyltetracarboxylic acid was dehydrated to produce 247 kg of 3,3', 4,4'-biphenyltetracarboxylic dianhydride.

Next, using this 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, an aromatic polyamic acid was synthesized in the same manner as in Example 1 to obtain the logarithmic viscosity of the polymerization reaction solution. Was calculated. Table 1 shows the results of the dehydration and the logarithmic viscosity of the polymerization reaction solution.

[Comparative Example 1] Using the same reaction vessel and raw material as in Example 1, a high temperature heat-resistant heat medium was circulated in the jacket of the reaction vessel to carry out each heat treatment, and the crystals in the reaction vessel were used. Example 1 except that the temperature was raised from 80 ° C. to 280 ° C. in one step in 2 hours (average temperature rising rate 100 ° C./hour), and then the crystal was maintained at 280 ° C. for 5 hours.
The dehydration reaction is performed under the same reaction conditions as in 3,
246 kg of 3 ', 4,4'-biphenyltetracarboxylic dianhydride was produced.

Next, using this 3,3 ', 4,4'-biphenyltetracarboxylic dianhydride, an aromatic polyamic acid was synthesized in the same manner as in Example 1 to obtain the logarithmic viscosity of the polymerization reaction solution. Was calculated. Table 1 shows the results of the dehydration and the logarithmic viscosity of the polymerization reaction solution.

[0038]

[Table 1]                                 Table 1     ──────────────────────────────────                     Total acid dehydration rate Tri-acid logarithmic viscosity                        (%) (%) (%)     ──────────────────────────────────       Example 1 100 100 0.06 4.0       Example 2 100 100 0.06 4.0       Example 3 100 100 0.07 3.8       Comparative Example 1 99.0 99.0 0.3 2.3     ──────────────────────────────────

Total acid: Content of biphenyltetracarboxylic dianhydride in the dehydrated product. Dehydration rate: Producing rate of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride with respect to the raw material. Triacid: Content of biphenyl tricarboxylic acids in the product.

[0040]

[Equation 2] (Measurement temperature; 30 ° C., concentration: 0.5 g (polymer) / 1
00 mL solvent, solvent: N-methyl-2-pyrrolidone)

From the above results, the use of the biphenyltetracarboxylic dianhydride of the present invention in which the content of biphenyltricarboxylic acids is extremely small makes it possible to obtain a known aromatic polyamic acid having a high viscosity (that is, a high molecular weight). It can be seen that it can be produced by a polymerization reaction with a diamine.
On the other hand, when a mixed amount of biphenyl tricarboxylic acids is higher than the value specified in the present invention, when the biphenyl tetracarboxylic dianhydride is used, the viscosity of the aromatic polyamic acid obtained is obviously lowered, and a high molecular weight one is obtained. It is also clear that it is difficult to obtain.

[0042]

INDUSTRIAL APPLICABILITY The biphenyltetracarboxylic dianhydride of the present invention, in which the content of biphenyl tricarboxylic acid and its acid anhydride is extremely low, less than 0.15% by weight, is polymerized with an aromatic diamine by a known method. Produces a high molecular weight aromatic polyamic acid.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Genji Koga Ube City, Ube City, Yamaguchi Prefecture Kogushi 1978-10 Ube Industries, Ltd. Ube Chemical Factory (56) References JP-A-60-81154 (JP, A) ( 58) Fields investigated (Int.Cl. ⁷ , DB name) C07D 307/89

Claims (4)

(57) [Claims] 1. A crystal of biphenyltetracarboxylic acid is added.
Biphenyl tetracarbo obtained by heat treatment
An acid heat-anhydride product, the heat treatment of which is reduced
In both cases, the average heating rate from 80 ° C to 250 ° C is 50 ° C /
Do not be higher than time, then 250-3
By heating at a temperature of 00 ° C for at least 3 hours.
Becomes, the biphenyl tricarboxylic acids and / or their anhydrides
A biphenyltetracarboxylic acid heat-anhydride product, characterized in that the content of the substances is adjusted to be less than 0.15% by weight with respect to the biphenyltetracarboxylic dianhydride. 2. The biphenyltetra according to claim 1, wherein the content of biphenyltricarboxylic acid and / or its anhydride in the reaction product is less than 0.1% by weight based on biphenyltetracarboxylic dianhydride. Carboxylic acid heat-anhydride product. 3. The heat dehydration of biphenyltetracarboxylic acid according to claim 1, wherein the heat dehydration of biphenyltetracarboxylic acid is carried out in the absence of a solvent and under an inert gas atmosphere. Product. 4. A temperature of at least 80 ° C. to 250 ° C.
The heat treatment is performed with the process of interrupting the temperature rise in the middle.
A biphenyltetracarboxylic acid heat-anhydride product according to any one of claims 1 to 3 .