JPS6340810B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an aromatic polyamide-imide, and more particularly to a method for producing a powdery aromatic polyamide-imide with improved thermal stability by precipitation polycondensation. Aromatic polyamide-imide has excellent heat resistance, mechanical properties, electrical properties, and chemical resistance similar to aromatic polyimide, as well as processability that aromatic polyimide lacks, making it an important industrial material. It has been attracting attention in recent years. Conventionally, various methods for producing aromatic polyamideimide have been known, including a method by solution polycondensation of aromatic tricarboxylic acid anhydride monohalide and aromatic diamine, and a method using aromatic tricarboxylic acid anhydride and aromatic diisocyanate. There are methods such as solution polycondensation with. However, in these methods, the produced polymer is obtained in a solution state, so in order to obtain granular or powdery solid aromatic polyamideimide, complicated and expensive solid polymer isolation such as non-solvent precipitation is required. The disadvantage is that it requires several steps. As a method to overcome these drawbacks, a method has recently been proposed in which trimellitic anhydride and diisocyanate are subjected to precipitation polycondensation using an aprotic solvent such as nitrobenzene with a dielectric constant of 10 or more and a tertiary amine catalyst. (Polymer Chemistry Vol. 29, No. 323, p182-185 (1972),
and Special Publication No. 54-44719). This method is an industrially useful method since it is possible to obtain a solid aromatic polyamideimide having a sufficiently high molecular weight in one step and in a high yield. In this method, in addition to the type of solvent, the third
Selection of the type of class amine is the key to obtaining a high molecular weight aromatic polyamideimide in a good granular or powder form, and triethylenediamine or tri-n-butylamine is used as such a catalyst. However, these catalysts have some serious drawbacks. That is, the former catalyst is effective for increasing the molecular weight, but since it is substantially non-volatile, it tends to remain in the resulting polymer, resulting in a polymer with poor thermal stability. The catalyst itself is expensive, and it is difficult to recover it by practical methods such as distillation, which reduces the economic efficiency that should be a feature of the precipitation polycondensation method. There are other inconveniences. Further, although the latter catalyst is volatile, it has the disadvantage that it lacks the ability to achieve a sufficiently high molecular weight, which is the most basic requirement. As a way to solve these inconveniences, 1, 8
-diazabicyclo[5,4,0]undecene-7
An improved method was proposed to use the catalyst as a catalyst.
Publication No. 410). However, although this method is effective against the above-mentioned disadvantages, it has not been able to solve both of them at the same time. Under such circumstances, the present inventors have developed an aromatic polyamide-imide production method based on the economically advantageous precipitation polycondensation method of aromatic tricarboxylic acid anhydrides and aromatic diisocyanates.
As a result of intensive research to establish a method that overcomes all of the above disadvantages, we found that when a tertiary amine with a boiling point lower than the reaction temperature is used as a catalyst, an aromatic compound with a sufficiently high molecular weight and excellent thermal stability. The present invention was completed by discovering that polyamideimide can be obtained in a good powder form. That is, the present invention uses aromatic polycarboxylic acids mainly consisting of aromatic tricarboxylic acid anhydrides and polyisocyanates mainly consisting of aromatic diisocyanates in a solvent selected from the group consisting of nitrobenzene, nitrotoluenes, benzonitrile, and acetonitrile. The present invention provides a method for producing powdery polyamide-imide, characterized in that a tertiary amine having a boiling point of about 110°C or less is used as a catalyst in a method of carrying out precipitation polycondensation at a temperature of about 110 to 200°C. be. The aromatic polycarboxylic acids used in the present invention have the general formula This is a group of compounds that contain an aromatic tricarboxylic acid anhydride represented by 50% by mole or more as a main component, and may also contain dicarboxylic acid and/or tetracarboxylic dianhydride in a proportion of less than 50% by mole. Here, Ar is an aromatic trivalent residue, and is characterized in that the divalents to which the two carbonyl groups forming the acid anhydride group are bonded are on adjacent carbon atoms. A specific example of such Ar ₁ is

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[expression] and etc. Specific examples of the aromatic tricarboxylic anhydride represented by the general formula () are trimellitic anhydride, 1,2,3-benzenetricarboxylic anhydride, 1,2,4-, 1,4,5- and 2 ,3,
6-naphthalene tricarboxylic anhydride, 3,4,
4′-diphenyl ether tricarboxylic anhydride,
Examples include 3,4,4'-benzophenone tricarboxylic anhydride. Among these, a particularly preferred aromatic tricarboxylic anhydride is trimellitic anhydride. Examples of dicarboxylic acids that can be part of the aromatic polycarboxylic acids in a proportion of less than 50 mol% are terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, 4,4'-biphenyl dicarboxylic acid, 4,4 '-diphenyl ether dicarboxylic acid,
4,4'-benzophenonedicarboxylic acid, 4,4'-
Specific examples include diphenylmethanedicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, 2-methylterephthalic acid and adipic acid. Similarly, specific examples of tetracarboxylic dianhydride include pyromellitic dianhydride, benzophenonetetracarboxylic dianhydride, naphthalenetetracarboxylic dianhydride, and the like. The proportion of these dicarboxylic acids and/or tetracarboxylic dianhydrides in the polycarboxylic acid is 50 mol%
If the amount is more than this, the excellent properties of the aromatic polyamideimide may be impaired or precipitation polycondensation may not occur, which is not preferable. The polyisocyanates used in the present invention include aromatic diisocyanates represented by the general formula OCN-Ar ₂ -NCO () as a main component of 70 mol% or more, and aliphatic diisocyanates at a proportion of less than 30 mol%. , alicyclic diisocyanate, trifunctional or higher polyfunctional polyisocyanate,
and a group of compounds that may include mixtures thereof. Here, Ar ₂ is an aromatic divalent residue, and a specific example is

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[Formula] etc. can be mentioned. Examples of the aromatic diisocyanate represented by the general formula () are p-phenylene diisocyanate, m-phenylene diisocyanate, toluylene diisocyanate, diphenylmethane-4,
4'-diisocyanate, diphenyl ether-
4,4'-diisocyanate, biphenyl-4,
Specific examples include 4'-diisocyanate, 3,3'-dimethylbiphenyl-4,4'-diisocyanate, diphenyl sulfide-4,4'-diisocyanate, and naphthalene-2,6-diisocyanate. can. Examples of aliphatic diisocyanates, alicyclic diisocyanates, and trifunctional or higher functional polyisocyanates that can be part of polyisocyanates in a proportion of less than 30 mol% include hexamethylene diisocyanate, xylylene diisocyanate, and cyclohexane-1,4-diisocyanate. , dicyclohexylmethane-4,4'-diisocyanate, and isocyanurate ring-containing polyisocyanates obtained by trimerizing diisocyanates. These aliphatic diisocyanates,
The proportion of alicyclic diisocyanate and/or trifunctional or higher functional polyisocyanate in the polyisocyanate mainly consisting of aromatic diisocyanate is less than 30 mol%, and if it exceeds this amount, the excellent properties unique to aromatic polyamideimide will be lost. This is not preferable because it may cause loss of properties or prevent precipitation polycondensation. The object of the present invention can only be achieved by using as a catalyst a tertiary amine with a boiling point of about 110° C. or lower. Examples of such tertiary amines are trimethylamine, triethylamine, dimethyl-n-
Examples include butylamine, dimethylisobutylamine, dimethyl-n-propylamine, dimethylisopropylamine, diethylmethylamine, diethylallylamine, N-methylpiperidine, and the like. Among these, preferred tertiary amines having a boiling point of about 110° C. or less are trimethylamine and triethylamine. The solvent used in the process of the invention is selected from the group consisting of nitrobenzene, nitrotoluenes, benzonitrile and acetonitrile. Here, nitrotoluenes include 0-nitrotoluene,
Refers to m-nitrotoluene, p-nitrotoluene and mixtures thereof. In carrying out the method of the present invention, the aromatic polycarboxylic acids mainly consisting of aromatic tricarboxylic acid anhydride and the polyisocyanates mainly consisting of aromatic diisocyanates are used in the above solvent in an approximately equimolar ratio, and the above boiling point is about 110℃
The reaction is carried out by heating in the presence of the following tertiary amine. During the reaction, the tertiary amine is supplied to the reaction system in its entirety at once or in portions during the reaction or continuously. The amount of the amine used is 1 mol % or more based on the aromatic polycarboxylic acids commonly used. There is no particular restriction on the amount on the larger side as there is no particular disadvantage, but the preferable range in consideration of economic efficiency and the like is 5 to 200 mol %. If the amount used is less than 1 mol %, it is not preferable because the molecular weight may not be high enough or a stable slurry may not be formed. The above solvent is used in a state substantially free of water and other components that react with the polyisocyanate.
The ratio of monomer raw materials to the solvent is generally
The amount is 0.1 to 2 mol/, preferably 0.2 to 1 mol/. If the concentration is lower than 0.1 mol/mol, aromatic polyamideimide with a sufficiently high molecular weight cannot be obtained, and if the concentration is higher than 2 mol/mol/mol, undesirable side reactions such as gelation occur, so both are not preferred. When carrying out the method of the present invention, the reaction temperature is between 110 and 200.
°C, preferably in the range of 120 to 180 °C. If the reaction temperature is lower than 100°C, the reaction rate is very slow or a high molecular weight polymer cannot be obtained, which is undesirable, and if it is higher than 200°C, gelation occurs, which is undesirable. Suitable reaction times vary depending on other conditions, but are usually 0.5 to 20 hours, preferably 1 to 20 hours.
It's 10 o'clock. Moreover, it is preferable to be under vigorous stirring conditions during the reaction time. When carrying out the method of the present invention, there are no restrictions on the addition of a small amount of a molecular weight regulator or the like to the reaction system. Such molecular weight regulators include monocarboxylic acids such as benzoic acid, monoisocyanates such as phenyl isocyanate, dicarboxylic acid anhydrides such as phthalic anhydride, naphthalene dicarboxylic anhydride, succinic anhydride, and phenols. Examples include monofunctional compounds. Particularly preferred molecular weight regulators are dicarboxylic acid anhydrides. Thus, in the method of the present invention, as the polymerization reaction progresses, the produced polymer precipitates out in the form of powder, and after a predetermined period of reaction operation, the system forms a stable slurry. The slurry is subjected to solid-liquid separation means such as filtration or centrifugation to separate the solid aromatic polyamide-imide and the solvent phase. The obtained solid aromatic polyamide-imide is subjected to treatments such as washing with a polymer non-solvent such as acetone, methanol, or toluene, acidic water washing, water washing, or steam stripping as necessary, followed by vacuum drying and fluidization. The product is subjected to a normal drying process such as drying, and a powdered aromatic polyamide-imide product is obtained. The powdered aromatic polyamide-imide can be processed by heat processing as it is, or after being dissolved in an organic solvent.
It can be molded and used in molded products, paints, films, etc. According to the method of the present invention described in detail above, a simple process that does not require any special treatment for isolating a solid polymer from a solution, that is, a precipitation polycondensation method, can be used to isolate a solid polymer from a solution using a simple process such as the precipitation polycondensation method. It is possible to obtain powdered aromatic polyamideimide with excellent quality including good thermal stability, which could not be obtained by other methods, and to supply resin products with excellent heat resistance and mechanical properties at an extremely economical cost. Its industrial value is enormous. The method of the present invention will be explained in more detail with reference to Examples below, but the scope of the method of the present invention is not limited by these Examples. In addition, the reduced viscosity (ηsp/C) in the examples is 0.5 g/100 ml in N-methylpyrrolidone, 25
This is a value measured under ℃ conditions. Further, the tensile strength retention rate, which indicates the degree of thermal stability, is the following value, and the larger this value is, the better the thermal stability is. Tensile strength retention rate (%) = (Tensile strength of film exposed for 5 hours in an oven at 300°C, Kg/mm ² ) ÷ (Tensile strength of original film, Kg/mm ² ) × 100 Example 1 30 cm long Bigelow rectifier connected to a trap cooled with dry ice/acetone;
19.2 g of trimellitic anhydride, diphenylmethane-4,
4′-diisocyanate 25.0g, phthalic anhydride 0.3g
Then, 160 ml of nitrobenzene was taken and heated to an internal temperature of 140°C while stirring. 5.9 g of trimethylamine (boiling point: 3.2°C) was blown into this through the gas inlet, 1.2 g in the first 10 minutes, and the rest over 2 hours. During this time, the system was maintained at 140° C. with stirring, and this condition was maintained for an additional 3 hours even after the completion of blowing in trimethylamine. Then, the heating was stopped, and the mixture was allowed to cool while slowly blowing nitrogen through the gas inlet. After adding 100 ml of acetone to the resulting slurry, the precipitated polymer was separated. The wet polymer was boiled and washed with acetone, and then vacuum dried at 120°C for 24 hours.
35.2 g of yellow powdered polymer was obtained. It was confirmed by infrared spectrum that the polymer was polyamideimide. The reduced viscosity was 0.912 dl/g. Trimethylamine recovered in the trap was 5.4
g, and it was found that substantially the entire amount could be recovered. The powdered aromatic polyamide-imide obtained here was dissolved in N-methylpyrrolidone to make a 20% by weight solution, and the solution was coated on a glass plate at 100°C.
The film was dried for 4 hours at 250° C./6 hours to obtain a film with a thickness of about 50 μm. The tensile strength of the film at room temperature is 9.6
Kg/mm ² , and the tensile strength retention rate was 92%. Examples 2 to 4, Comparative Examples 1 to 3 Into the same reaction apparatus as in Example 1, 19.2 g of trimellitic anhydride, diphenylmethane-4,
4′-diisocyanate 25.0g, phthalic anhydride 0.3g
Then, 140 ml of 0-nitrotoluene was taken and heated to an internal temperature of 140°C while stirring. Half of a solution prepared by dissolving 0.3 mol of the tertiary amine shown in Table 1 in 20 ml of 0-nitrotoluene was added thereto. 140℃
The remaining tertiary amine solution was further added after 3 hours had elapsed since the addition of the amine. After stirring was continued for an additional 5 hours while maintaining the temperature at 140°C, the pressure of the system was reduced by pulling nitrogen from the tip of the trap with a vacuum pump while blowing nitrogen through the gas blowing tube. The distillate was collected in a trap. The obtained slurry was treated in the same manner as in Example 1 to obtain a powdery aromatic polyamide-imide. Table 1 shows the yield and other results, as well as the evaluation results of the cast film obtained in the same manner as in Example 1. Examples 5-7 Diphenylmethane-4,4'-diisocyanate
A powdered aromatic polyamide-imide was produced and a cast film was evaluated in the same manner as in Example 2, except that 25.0 g (0.1 mol) was changed to the polyisocyanates and amounts shown in Table 2. These results are shown in Table 2. In all cases, the recovery rate of triethylamine was 93% or more.

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Claims (1)

[Scope of Claims] 1. Aromatic polycarboxylic acids mainly consisting of aromatic tricarboxylic acid anhydrides and polyisocyanates mainly consisting of aromatic diisocyanates selected from the group consisting of nitrobenzene, nitrotoluenes, benzonitrile and acetonitrile. 1. A method for producing a powdery aromatic polyamide-imide, the method comprising precipitation polycondensation using a solvent at a temperature of about 110 to 200°C, and using a tertiary amine having a boiling point of about 110°C or less as a catalyst. 2. The method for producing a powdery aromatic polyamide-imide according to claim 1, wherein the tertiary amine having a boiling point of about 110° C. or lower is trimethylamine and/or triethylamine. 3. The method for producing a powdery aromatic polyamide-imide according to claim 2, wherein the solvent is nitrobenzene and/or nitrotoluenes. 4 Polyisocyanates are diphenylmethane
4,4'-diisocyanate, diphenyl ether-4,4'-diisocyanate, and tolylene diisocyanate, which is an aromatic diisocyanate selected from the group consisting of tolylene diisocyanate. . 5. The method for producing a powdery aromatic polyamideimide according to claim 4, wherein the aromatic polycarboxylic acid is trimellitic anhydride. 6. The method for producing a powdery aromatic polyamide-imide according to claim 5, wherein the solvent is nitrotoluenes.