JP4118649B2 - Method for producing mixed solution of aromatic polyamide and aromatic polyamic acid - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a mixed solution of an aromatic polyamide and an aromatic polyamic acid. More specifically, a method for producing a stable mixed solution of an aromatic polyamide and an aromatic polyamic acid suitable as a precursor for producing a molded article such as a fiber or film in which an aromatic polyamide and an aromatic polyimide are combined. Is to provide.
[0002]
[Prior art]
Aromatic polyamide resin has a structure in which rigid aromatic rings are connected by amide bonds, and is an excellent material with excellent heat resistance, mechanical properties, chemical resistance, etc. It is one of the most valuable industrial materials that are widely used such as chemicals and bulletproof fibers. On the other hand, an aromatic polyimide resin having an imide structure at the aromatic ring bonding site has also been put to practical use as a constituent material for thin-layer electronic components such as electronic packaging, taking advantage of its excellent heat resistance and mechanical properties. Has been done. As described above, although both polymers having similar chemical structures are being used in various fields, resin compositions composed of both polymers and composites combined at the molecular level have hardly been studied. . In various applications where aromatic polyamides are used, even though there are many fields where higher Young's modulus is preferred, aromatic polyimides that are stiffer and have higher theoretical elastic modulus than polyamides can be combined with polyamides as reinforcing agents. There have been very few attempts to use it so far.
[0003]
One of the causes seems to be the difficulty of the manufacturing method. In general, an aromatic polyimide resin is insoluble in a solvent. Accordingly, a polyimide is usually an aromatic obtained by reacting an aromatic diamine with an aromatic tetracarboxylic dianhydride in the presence of an amide solvent such as N-methyl-2-pyrrolidone (hereinafter abbreviated as NMP). A polyamic acid solution is used as a precursor thereof. For example, a solution film is cast, and then amic acid is dehydrated and closed by heating to obtain a polyimide film. Thus, since the precursor polyamic acid is obtained as a solution of an amide solvent in the same manner as the polyamide, it can be easily mixed with an aromatic polyamide solution in the state of the precursor solution in order to obtain a polyamide / polyimide composite. Conceivable. Several mixed solutions of polyamide and polyamic acid have been reported so far (Patent Document 1 or Patent Document 2), and all of them are isolated from aromatic polyamides and used as a polyamide solution after being dissolved in a solvent. Yes. This is because polyamide is also obtained by reacting an aromatic diamine with an aromatic dicarboxylic acid chloride in the presence of an amide solvent such as NMP, but when the solution obtained as such is mixed with polyamic acid, Although they mixed well with each other to form a uniform solution, there was a problem that the resulting mixed solution became unstable when simply mixed. Even at high temperature or at room temperature, the viscosity of the solution decreases with time. This is presumably because the polyamic acid is hydrolyzed by the water present in the mixed solution, but the water is mainly derived from the aromatic polyamide solution. In general, the hydrochloric acid generated during the polymerization of polyamide is neutralized by inorganic alkali salts such as calcium hydroxide and lithium hydroxide, and as a result, a certain amount of water is present in the polyamide solution. is there.
[0004]
Due to the above circumstances, in order to obtain a stable mixed solution of an aromatic polyamide and an aromatic polyamic acid using an usually obtained aromatic polyamide solution, it is necessary to remove water in the solution. There are several methods for removing water, but a method of adding a solvent azeotropic with water and removing it by azeotropic distillation is known. For example, as a method of removing water generated when an aromatic polyamic acid is heated and imidized in a solution state, a method of adding a azeotropic solvent to a polyamic acid solution and carrying out heat ring closure has been reported (for example, non-patent) Reference 1). Even in the case of a polyamide solution, an example using an azeotropic solvent has been reported (see Patent Document 3). As described above, in the case of the aromatic polyamide solution or the aromatic polyamic acid solution alone, although there is an example using an azeotropic solvent, a method for producing a mixed solution of the two has not yet been reported. There was a need to search for a stable mixed solution.
[0005]
[Non-Patent Document 1]
Andrew E.E. Feiring et al., Macromolecules 1993, 26, 2779, page 2781, Solution Polyimide column [0006]
[Patent Document 1]
Japanese Examined Patent Publication No. 01-29383, paragraph 2 [0007]
[Patent Document 2]
Japanese Patent Laid-Open No. 09-143282, paragraph 5
[Patent Document 3]
JP-A-60-35946, page 1 [0009]
[Problems to be solved by the invention]
The objective of this invention is providing the manufacturing method of the stable mixed solution by which the fall of the solution viscosity was suppressed even in the high temperature state in the solution which consists of aromatic polyamide and aromatic polyamic acid.
[0010]
[Means for Solving the Problems]
The present inventors have studied various methods for mixing an aromatic polyamide solution and an aromatic polyamic acid solution. As a result, the inventors found that the method of stirring and mixing a mixture obtained by adding a solvent azeotropic with water to each polymer solution can produce the most efficient and stable mixed solution by heating and distilling. did.
[0011]
That is, in the present invention, when preparing a mixed solution of an aromatic polyamide and an aromatic polyamic acid, a mixture of each polymer solution and a solvent azeotroped with water is distilled by heating to distill off the water and the solvent in the system. It is a manufacturing method of the mixed solution of aromatic polyamide and aromatic polyamic acid characterized by carrying out stirring mixing.
[0012]
Preferable aromatic polyamic acid in this case is substantially obtained by reaction of p-phenylenediamine and pyromellitic dianhydride. Moreover, N-cyclohexyl-2-pyrrolidone can be mentioned preferably as a solvent azeotropic with water.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
[0014]
The aromatic polyamide used in the present invention is obtained by connecting aromatic rings with amide bonds. Polyamide is usually synthesized by a solution polymerization method in which an aromatic dicarboxylic acid chloride and an aromatic diamine are reacted in the presence of an amide solvent.
[0015]
Specific examples of the aromatic dicarboxylic acid chloride include terephthalic acid chloride, isophthalic acid chloride, and 2,6-naphthalenedicarboxylic acid chloride.
[0016]
Specific examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 3,4'-diaminodiphenyl ether, 4, 4'-diaminodiphenyl ether, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylsulfide, 4 , 4'-diaminodiphenyl sulfide and the like.
[0017]
Among these combinations, considering the balance of cost, solubility of the resulting polymer, and physical properties, terephthalic acid chloride is used as the dicarboxylic acid chloride component, and p-phenylenediamine alone or p-phenylenediamine is used as the diamine component. An aromatic polyamide using a composition with 3,4'-diaminodiphenyl ether can be preferably exemplified.
[0018]
The molecular weight of the aromatic polyamide can be controlled by the ratio of the diamine and dicarboxylic acid chloride used in the polymerization, but the molar ratio of the dicarboxylic acid chloride to the diamine is 0.90 to 1.10, more preferably 0.95 to 1.05. It is preferable to use in the range of.
[0019]
Examples of the solvent used in the polymerization reaction include NMP, N, N-dimethylformamide, N, N-dimethylacetamide, tetramethylurea, hexamethylphosphoramide, and mixed solvents thereof. In practice, NMP is preferably used. The polymer concentration is 1 to 30% by weight, preferably 2 to 20% by weight.
[0020]
In the polymerization reaction, hydrochloric acid is produced as a result, and after the polymerization reaction, an inorganic alkali salt such as calcium hydroxide or lithium hydroxide is usually added as a neutralizing agent to carry out a neutralization reaction. As a result, a predetermined amount of water is generated. .
[0021]
The aromatic polyamic acid used in the present invention is an aromatic ring bonded in the form of an amic acid, and reacts an aromatic tetracarboxylic dianhydride with an aromatic diamine in the presence of an amide solvent. Is obtained.
[0022]
Specific examples of the aromatic tetracarboxylic dianhydride include pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3 ′, 4,4′-biphenyl. Tetracarboxylic dianhydride, 2,3,3 ′, 4′-biphenyltetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4 ′ -Benzophenone tetracarboxylic dianhydride, 2,3,3 ', 4'-benzophenone tetracarboxylic dianhydride, 2,3,5,6-pyridinetetracarboxylic dianhydride, 2,3,4,5 -Thiophenetetracarboxylic dianhydride, 2,2-bis (3,4-dicarboxyphenyl) propane dianhydride, bis (3,4-dicarboxyphenyl) ether dianhydride, bis (3,4-di Carboxyphenyl) methane Things and the like. Specific examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, 1,4-diaminonaphthalene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 3,4'-diaminodiphenyl ether, 4 , 4′-diaminodiphenyl ether, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenylsulfone, 4,4′-diaminodiphenylsulfone, 3,4′-diaminodiphenylsulfide, 4,4′-diaminodiphenyl sulfide and the like. Among these combinations, the aromatic polyamic acid obtained by the reaction of p-phenylenediamine and pyromellitic dianhydride is excellent in both physical properties and economy that the rigidity is extremely high. Preferably, it can be mentioned in terms of the composite.
[0023]
Although the molecular weight of the aromatic polyamic acid obtained by polymerization can be controlled by the ratio of these diamines and tetracarboxylic dianhydrides, the molar ratio of tetracarboxylic dianhydrides to diamines is 0.90 to 1.10. It is preferably used in the range of 0.95 to 1.05.
[0024]
The aromatic polyamic acid is obtained by solution polymerization in the presence of an amide solvent in the same manner as the aromatic polyamide. Examples of the solvent used in this case include NMP, N, N-dimethylformamide, N, N-dimethylacetamide, tetramethylurea, hexamethylphosphoramide, and mixed solvents thereof, but NMP is preferable for practical use. Used. The polymer concentration is 0.5 to 30% by weight, preferably 1 to 15% by weight. The polymerization is an exothermic reaction and is performed at a low temperature.
[0025]
The composition of the aromatic polyamide and the aromatic polyamic acid in the mixed solution is not particularly limited, and it is possible to prepare a mixed solution of both polymers at an arbitrary ratio, but by combining with a rigid polyimide, the polyamide In consideration of enhancing the mechanical properties, a mixed solution in which the aromatic polyamic acid component is 2 to 50% by weight, more preferably 5 to 30% by weight of the whole polymer component can be preferably exemplified.
[0026]
In the present invention, in producing a mixed solution of both polymers, a mixture is first prepared by adding a solvent azeotropic with water to a polyamide solution and a polyamic acid solution. The solutions of both polymers are preferably the same solvent, and more preferably both are NMP.
[0027]
Specific examples of solvents azeotropic with water include benzene, toluene, xylene, N-cyclohexyl-2-pyrrolidone, chloroform, methylene chloride, carbon tetrachloride, o-dichlorobenzene, 1,4-dioxane, 1,3- Examples include dioxolane. Among these, N-cyclohexyl-2-pyrrolidone itself is also an amide solvent, so even if it is added to the solution, it does not interfere with the solubility of the polymer, and is compatible with water. When subjected to membrane or wet spinning, it can be said to be a preferred solvent because it is easily dissolved in a coagulation bath usually composed of water and NMP.
[0028]
The amount of the solvent azeotroped with water varies depending on the amount of water present in the solution and the type of solvent, and is not particularly limited, but it is an amount that can completely remove water by azeotropy and does not precipitate both polymers. In general, it is selected in the range of 1 to 150% by weight, preferably 5 to 50% by weight, based on the combined amount of the polyamide solution and the polyamic acid solution.
[0029]
When the mixture of the present invention comprising a polyamide solution, a polyamic acid solution, and a solvent azeotroped with water is preferably mixed at the lowest possible temperature in an inert gas atmosphere in order to suppress decomposition of the polyamic acid. In consideration of practicality, it is preferably performed in the range of 0 to 30 ° C. In general, both the polyamide solution and the polyamic acid solution have extremely high viscosities, and it is difficult to achieve complete compatibility between the two solutions by simply mixing at such a low temperature and simply stirring. Add boiling solvent, stir and mix gradually from low temperature, and simultaneously distill off water and solvent by distillation. By this method, not only the water present in the polyamide solution but also the water derived from the polyamic acid solution can be completely removed at the same time, so that a very stable mixed solution in which a decrease in solution viscosity due to hydrolysis is suppressed even after mixing. Can be created.
[0030]
Although distillation can be carried out under an inert gas atmosphere and at normal pressure, it is preferable to distill water off as quickly as possible without increasing the temperature in order to suppress decomposition of the polyamic acid. Preferably it is done. In such a case, if the temperature is raised too much, the imidization reaction of the polyamic acid proceeds and is not preferable because it may cause precipitation or gelation by insolubilization in the solvent. The removal of water does not proceed sufficiently, which is not preferable. Specifically, the temperature of the mixture in the system when stirring and mixing while distillation is preferably 60 ° C or higher and 150 ° C or lower, and more preferably 60 ° C or higher and 120 ° C or lower. In this case, there is no problem even if a part of the original amide solvent such as NMP itself is distilled off after the azeotrope as a fraction, and therefore the polymer concentration can be adjusted by the amount of distillation. is there.
[0031]
The total polymer concentration in the mixed solution thus obtained is 1 to 30% by weight, preferably 2 to 20% by weight, more preferably 4 to 15% by weight.
[0032]
【Example】
The present invention is described in detail below with reference to examples. However, the present invention is not limited to these examples.
[0033]
N-methyl-2-pyrrolidone and N-cyclohexyl-2-pyrrolidone, which are the solvents used in the production examples and the examples, were purified by distillation and sufficiently dried. As terephthalic acid chloride and pyromellitic dianhydride, those purchased as reagents were used as they were. As p-phenylenediamine and 3,4′-diaminodiphenyl ether, those purchased as reagents were distilled and used.
[0034]
Solution viscosities carried out in Examples and Comparative Examples were measured as follows.
Solution viscosity: A B-type viscometer (VTB-250, B8U type) manufactured by Toki Sangyo Co., Ltd. was used. The solution was added to the cup and measured under a nitrogen atmosphere at a rotation speed of 0.5 rpm.
[0035]
[Production Example 1]
Under a nitrogen atmosphere, 5.41 g of p-phenylenediamine and 10.01 g of 3,4′-diaminodiphenyl ether were dissolved in 490 mL of N-methyl-2-pyrrolidone, and this solution was cooled to 0 ° C. 20.30 g of acid chloride powder was added. The solution gradually increased in viscosity while generating heat, and became a transparent high-viscosity solution. The temperature increase was started 3 hours after the addition of terephthalic acid chloride, and the mixture was further stirred for 2 hours after the oil bath temperature reached 70 ° C. Thereafter, a slurry in which 7.41 g of calcium hydroxide was dispersed in 20 g of NMP was added, and the mixture was further stirred at 70 ° C. for 1 hour to neutralize by-produced hydrochloric acid, and then cooled to room temperature. The solution viscosity of the aromatic polyamide solution thus obtained was 37,000 ps (poise) at 30 ° C.
[0036]
[Production Example 2]
Under nitrogen atmosphere, p-phenylenediamine (5.41 g) was dissolved in N-methyl-2-pyrrolidone (380 mL), and the solution was cooled to 0 ° C., and then pyromellitic dianhydride powder (10.91 g) was vigorously stirred. Was added. The solution gradually increased in viscosity while generating heat, and became a transparent high-viscosity solution. While cooling to 0 ° C., pyromellitic dianhydride anhydride was added and stirred for 3 hours. The solution viscosity of the aromatic polyamic acid solution thus obtained was 3,000 ps at 30 ° C.
[0037]
[Example 1]
300 g of the polyamide solution obtained in Production Example 1 and 125 g of the polyamic acid solution obtained in Production Example 2 were mixed at 25 ° C. in a nitrogen atmosphere, and 100 mL of N-cyclohexyl-2-pyrrolidone was further added thereto. The mixture was stirred while being reduced in pressure by a vacuum pump so as to be in a reduced pressure state of about 15 to 20 mmHg, and at the same time, the temperature was raised from 25 ° C. After 40 minutes from the start of temperature increase, the temperature of the oil bath reached 100 ° C., and the mixture was further stirred at 100 ° C. for 1 hour to obtain a uniform transparent mixed solution of polyamide / polyamic acid = 75/25 (weight ratio). During this time, the amount of the solvent distilled off by distillation was 31.5 g. The solution viscosity of this mixed solution was 11,200 ps at 30 ° C. Furthermore, when the measurement solution was placed in a B-type viscometer cup at 100 ° C. in a nitrogen atmosphere and the change in the solution viscosity over time was measured while stirring the rotor, it was 320 ps after 30 minutes and 310 ps after 2 hours. It was found that the solution was stable at high temperatures.
[0038]
[Example 2]
Except for changing the amount of polyamide solution to 360 g and the amount of polyamic acid solution to 50 g, mixing and vacuum distillation were carried out in the same manner as in Example 1 to obtain a homogeneous transparent solution of polyamide / polyamic acid = 90/10 (weight ratio). Obtained. During this time, the amount of the solvent distilled off by distillation was 36.2 g. The solution viscosity of this mixed solution was 18,000 ps at 30 ° C. Further, when the change in solution viscosity with time at 100 ° C. was measured in the same nitrogen atmosphere as in Example 1, the solution was stable at 540 ps 30 minutes after the start of measurement and 540 ps after 2 hours, and stable even at high temperatures. I found out.
[0039]
[Comparative Example 1]
Similarly to Example 1, 300 g of the polyamide solution obtained in Production Example 1 and 125 g of the polyamic acid solution obtained in Production Example 2 were mixed at 25 ° C. in a nitrogen atmosphere. Thereafter, unlike Example 1, the mixture was stirred for 2 hours in a nitrogen atmosphere at 25 ° C. to obtain a uniform transparent mixed solution of polyamide / polyamic acid = 75/25 (weight ratio). The solution viscosity of this mixed solution was 14,800 ps at 30 ° C. Furthermore, when the change in the viscosity of the solution with time was measured while stirring the rotor at 100 ° C. in a nitrogen atmosphere as in Example 1, it was as low as 160 ps 30 minutes after the start of the measurement, and further 70 ps after 2 hours. It was found that the viscosity drop was significant.
[0040]
[Comparative Example 2]
Polyamide / polyamic acid was mixed and distilled under reduced pressure in the same manner as in Example 1 except that 100 mL of N-cyclohexyl-2-pyrrolidone initially added in Example 1 was changed to 100 mL of N-methyl-2-pyrrolidone. = 75/25 (weight ratio) uniform transparent solution was obtained. During this time, the amount of the solvent distilled off by distillation was 25.6 g. The solution viscosity of this mixed solution was 2700 ps at 30 ° C., which was significantly lower than that of Example 1, and was inappropriate as a fiber spinning solution.
[0041]
【The invention's effect】
According to the present invention, a stable mixed solution of an aromatic polyamide and an aromatic polyamic acid can be obtained. Since the solution can suppress a decrease in solution viscosity due to hydrolysis of polyamic acid even at a high temperature, the precursor thereof is used when a molded body such as a fiber or a film in which an aromatic polyamide and an aromatic polyimide are combined is produced. It is effective as a body solution.

Claims (3)

When preparing a mixed solution of aromatic polyamide and aromatic polyamic acid, the mixture of each polymer solution and a solvent azeotroped with water is heated and distilled to stir and mix while distilling off the water and solvent in the system. A method for producing a mixed solution of an aromatic polyamide and an aromatic polyamic acid. The mixture of aromatic polyamide and aromatic polyamic acid according to claim 1, wherein the aromatic polyamic acid is substantially obtained by the reaction of p-phenylenediamine and pyromellitic dianhydride. A method for producing a solution. The method for producing a mixed solution of an aromatic polyamide and an aromatic polyamic acid according to claim 1 or 2, wherein N-cyclohexyl-2-pyrrolidone is added as a solvent azeotropic with water.