JPWO2010131421A1 - Method for producing polybenzoxazole film - Google Patents

Abstract

The present invention relates to a substituted polyamide that is a precursor of polybenzoxazole, wherein the polyamide has a hydroxy group in an ortho position with respect to an amide group, and at least a part of the hydroxy group is substituted with a tert-butoxycarbonyl group. Disclose what is being done. The present invention also provides a method for producing polybenzoxazole in which carbon nanotubes are uniformly dispersed, wherein (i) silylated 4,6-diaminoresorcinol and terephthalic acid chloride are reacted to form an ortho position relative to the amide group. (Ii) a step of substituting at least a part of the hydroxy groups in the synthesized polyamide with a tert-butoxycarbonyl group to obtain a substituted polyamide; (iii) Adding carbon nanotubes to a solution dissolved in a solvent, and dispersing the carbon nanotubes to prepare a dispersion; and (iv) heating the dispersion to cyclize the polybenzoxazole in which the carbon nanotubes are uniformly dispersed. A method comprising the steps of obtaining is disclosed.

Description

  The present invention relates to a substituted polyamide which is a precursor of polybenzoxazole, and a method for producing the same. The present invention also relates to a method for producing a polybenzoxazole film using such a substituted polyamide. Furthermore, the present invention relates to a polybenzoxazole in which carbon nanotubes are uniformly dispersed and a method for producing the film.

  A polybenzoxazole film is expected to have high strength, high elastic modulus, high heat resistance, and dimensional stability because of its chemical structure, and various production methods have been proposed so far.

  As a method for producing a polybenzoxazole film, for example, a casting method (Patent Document 1) and a biaxial stretching method using a blow molding method (Patent Document 2) have been proposed.

  In these conventional production methods, a film is produced from an optically anisotropic solution in which polybenzoxazole having a rigid molecular structure is dissolved at a high concentration. Therefore, the obtained film has a mechanical property depending on the properties of this solution. Strong anisotropy. Specifically, films thus produced directly from polybenzoxazole solutions have mechanical properties in the machine direction (direction in which the solution is extruded and stretched) and in the transverse direction (perpendicular to the machine direction). There was a problem that the balance, particularly the balance of strength, was poor.

  In response to this problem, an attempt has been made to produce a polybenzoxazole film having a balanced mechanical property by using an isotropic precursor solution having no rigid molecular structure. For example, Patent Document 3 proposes a method for producing a precursor of polybenzoxazole, and the precursor obtained by this method is easily dissolved in an organic solvent and formed into an arbitrary shape from this solution. It is described that a polybenzoxazole having a desired shape can be obtained by ring-closing with heating, for example, a film-like polybenzoxazole can also be produced.

  However, in this patent document 3, the solubility test of the precursor of polybenzoxazole and the shaping | molding to a film are not performed at all. According to the experiment which this inventor conducted, this precursor is an organic solvent. The solubility was insufficient, and cast film formation for film formation could not be performed sufficiently.

  On the other hand, since polybenzoxazole has high strength, high elastic modulus, and high heat resistance, it has been widely developed in various fields such as a magnetic recording film and a protective film on the structure surface. However, polybenzoxazole is inferior in light resistance, and has the disadvantage that the strength decreases when exposed to sunlight for a long time.

  In order to compensate for this drawback, Patent Document 4 proposes that a polybenzoxazole film contain carbon nanotubes. In the example of Patent Document 4, carbon nanotubes are added to a polymerization system when polybenzoxazole is directly polymerized from 4,6-diaminoresorcinol and terephthalic acid in polyphosphoric acid, and the obtained polymer dope is produced as it is. By forming a film, a polybenzoxazole film containing carbon nanotubes was produced, and it was confirmed that this film had light resistance.

  However, when the present inventor made a detailed analysis by pursuing the example of Patent Document 4, carbon nanotubes formed bundles or partly formed so-called lumps in the obtained film, and dispersion was not good. It was sufficient, and uniform light resistance could not be exhibited. In addition, other advantages expected from the addition of carbon nanotubes include improved strength, electrical conductivity, and thermal conductivity. However, these characteristics are also actually due to insufficient dispersion of carbon nanotubes. It was not improved.

U.S. Pat. No. 4,487,735 U.S. Pat. No. 2,898,924 JP-A-2-247225 JP 2003-327722 A

  The present invention was created in view of the current state of the prior art, and its object is to provide a polymer having excellent solubility in organic solvents and balanced mechanical properties (particularly strength) in the vertical and horizontal directions. An object of the present invention is to provide a precursor of polybenzoxazole, a method for producing the same, and a method for producing a polybenzoxazole film from the precursor, which can easily produce a benzoxazole film. Another object of the present invention is to provide a polybenzoxazole in which carbon nanotubes are uniformly dispersed and a method for producing the film.

  As a result of intensive studies to solve the above problems, the present inventor has determined that at least a portion of the hydroxy groups in the polyamide obtained by reacting a silylated product of 4,6-diaminoresorcinol with terephthalic acid chloride is tert. -Polyamide obtained by substitution with butoxycarbonyl has sufficient solubility in cast film formation, and when this substituted polyamide is used, a polybenzoxazole film having a balance of mechanical properties in the longitudinal and transverse directions is produced. I found that I can do it. In addition, the present inventor does not directly polymerize polybenzoxazole and add a carbon nanotube to the polymerization system at that time, but first synthesizes a polybenzoxazole precursor polyamide and produces a substituted polyamide from the polyamide. The present inventors have found that carbon nanotubes can be uniformly dispersed in polybenzoxazole by adding and dispersing carbon nanotubes in this substituted polyamide and then heating and ring-closing to convert the substituted polyamide into polybenzoxazole. The present invention has been completed based on these findings.

  That is, according to the present invention, there is provided a substituted polyamide which is a precursor of polybenzoxazole, wherein the polyamide has a hydroxy group in an ortho position relative to an amide group, and at least a part of the hydroxy group is tert-butoxy. Provided is a substituted polyamide characterized in that it is substituted with a carbonyl group.

Moreover, according to this invention, the manufacturing method of the above-mentioned substituted polyamide characterized by including the following processes is provided:
(I) reacting silylated 4,6-diaminoresorcinol with terephthalic acid chloride to synthesize a polyamide having a hydroxy group in the ortho position relative to the amide group; and (ii) at least one of the synthesized polyamides A step of substituting part of the hydroxy group with a tert-butoxycarbonyl group to obtain a substituted polyamide.

The present invention also provides a method for producing a polybenzoxazole film characterized by including the following steps:
(I) a step of obtaining a polyamide film by casting a solution obtained by dissolving the above substituted polyamide in an organic solvent; and (ii) a step of heating the polyamide film to cyclize to obtain a polybenzoxazole film.

In addition, according to the present invention, there is provided a method for producing polybenzoxazole in which carbon nanotubes are uniformly dispersed, including the following steps:
(I) adding carbon nanotubes to a solution of the above substituted polyamide in an organic solvent and dispersing the carbon nanotubes to prepare a dispersion; and (ii) heating the dispersion to close the ring, A step of obtaining polybenzoxazole in which is uniformly dispersed.

In addition, according to the present invention, there is provided a method for producing a polybenzoxazole film in which carbon nanotubes are uniformly dispersed, including the following steps:
(I) adding carbon nanotubes to a solution of the above substituted polyamide in an organic solvent and dispersing the carbon nanotubes to prepare a dispersion;
(Ii) a step of obtaining a polyamide film in which the carbon nanotubes are uniformly dispersed by casting the dispersion; and (iii) heating the polyamide film to close the ring to obtain a polybenzoxazole film in which the carbon nanotubes are uniformly dispersed. Obtaining step.

  The substituted polyamide which is a precursor of the polybenzoxazole of the present invention has high solubility in an organic solvent because at least a part of its hydroxy group is substituted with a tert-butoxycarbonyl group. If cast film formation is performed, a polybenzoxazole film having a good balance of mechanical properties (particularly strength) in the vertical and horizontal directions of the film can be easily obtained. Further, according to the production method of the present invention, since carbon nanotubes are added at the stage of substituted polyamide which is a precursor of polybenzoxazole, polybenzoxazole in which carbon nanotubes are uniformly dispersed and a film thereof can be easily obtained. it can.

The infrared absorption spectrum of N, N ', O, O'-tetra (trimethylsilyl) -4,6-diaminoresorcinol produced in Reference Example is shown. The ¹ H-NMR spectrum of N, N ′, O, O′-tetra (trimethylsilyl) -4,6-diaminoresorcinol produced in Reference Example is shown. The infrared absorption spectrum of the polyamide manufactured in Example 1 is shown. 2 shows an infrared absorption spectrum of the tert-butoxycarbonyl-substituted polyamide produced in Example 1. 1 shows the ¹ H-NMR spectrum of the tert-butoxycarbonyl-substituted polyamide produced in Example 1. The infrared absorption spectrum of the polybenzoxazole film manufactured in Example 3 is shown. The TGA chart of the solution for casting used in Example 3 is shown. The infrared absorption spectrum of the polybenzoxazole film manufactured in Example 4 is shown. The TGA chart of the solution for casting used in Example 4 is shown. The visible-near infrared absorption spectrum of the solution for casting used in Example 4 is shown. The visible-near-infrared fluorescence two-dimensional spectrum of the solution for casting used in Example 4 is shown.

  First, the substituted polyamide of the present invention will be described. The substituted polyamide of the present invention is a precursor of polybenzoxazole, wherein the polyamide has a hydroxy group in the ortho position with respect to the amide group, and at least a part of the hydroxy group is substituted with a tert-butoxycarbonyl group. It is characterized by being. Since the substituted polyamide of the present invention has at least part of its hydroxy group substituted with a tert-butoxycarbonyl group, it can be used for general-purpose organic solvents such as dimethylformamide, N-methyl-2-pyrrolidone, and N, N-dimethylacetamide. It has high solubility and can be easily cast into a film by dissolving in these organic solvents.

  In the substituted polyamide of the present invention, the tert-butoxycarbonyl group corresponds to a protecting group. In the present invention, it is important that the protecting group is a tert-butoxycarbonyl group. For protecting groups other than the tert-butoxycarbonyl group, such as a methyl group, an ethyl group, a phenyl group, and a benzyl group, when these groups are substituted with the hydroxyl group of the polyamide, basic conditions in which sodium hydroxide and the like exist are present. In this case, since the solubility of the polyamide is low and hydrolysis at the amide group site occurs, it is not easy to perform the substitution reaction. Even if the substitution can be made, the reaction of the deprotecting group must be carried out in the presence of palladium carbon or a strong acid. It is not suitable for the method of the present invention for carrying out the ring closure reaction to oxazole. On the other hand, if the protecting group is a tert-butoxycarbonyl group, the substitution of the polyamide with a hydroxyl group is easy, and the tert-butoxycarbonyl group is removed relatively easily during the ring-closing reaction from polyamide to polybenzoxazole. Progresses sufficiently.

The substituted polyamide of the present invention is produced by a production method including the following steps:
(I) reacting silylated 4,6-diaminoresorcinol with terephthalic acid chloride to synthesize a polyamide having a hydroxy group in the ortho position relative to the amide group; and (ii) at least one of the synthesized polyamides A step of substituting part of the hydroxy group with a tert-butoxycarbonyl group to obtain a substituted polyamide.

The silylated 4,6-diaminoresorcinol used in step (i) can be obtained, for example, by reacting commercially available 4,6-diaminoresorcinol dihydrochloride with a silylating agent in an organic solvent. (See Equation 1 below). After completion of the reaction of Formula 1, vacuum distillation is performed to isolate the desired silylated product.

  As the silylating agent in the reaction of Formula 1, a general silylating agent can be used. Specifically, hexamethyldisilazane, chlorotrimethylsilane, or a mixture thereof can be used. As the organic solvent, aromatic solvents such as benzene, toluene, xylene and anisole, and those obtained by dehydration treatment of tetrahydrofuran, carbon tetrachloride and the like can be used. The reaction temperature is usually 80 to 130 ° C. The reaction time is usually 1 hour to 100 hours. When the time is less than 1 hour, the amount of unreacted substances may increase. When the time is longer than 100 hours, the product may be decomposed to reduce the yield.

The terephthalic acid chloride used in step (i) can be obtained, for example, by reacting terephthalic acid with thionyl chloride (see Formula 2 below).

  Moreover, a commercial item may be used for the terephthalic acid chloride of a process (i). In either case, in order to obtain a polyamide with a high degree of polymerization, it is desirable to purify by recrystallization from an organic solvent. As this organic solvent, hexane, cyclohexane, cyclohexanone, or the like can be used.

In step (i), the silylated 4,6-diaminoresorcinol prepared as described above and terephthalic acid chloride are reacted to synthesize a polyamide having a hydroxy group in the ortho position relative to the amide group (the following formula 3). Specifically, this step can be performed by preparing an exact equimolar amount of silylated 4,6-diaminoresorcinol and terephthalic acid chloride and reacting them in an organic solvent at a low temperature.

  As an organic solvent in the reaction of Formula 3, dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, pyridine, tetrahydrofuran, 1,4-dioxane, carbon tetrachloride, chloroform, tetrachloroethane and the like are dehydrated. Can be used. Although reaction temperature changes with kinds of organic solvent to be used, it is 60--10 degreeC normally, Preferably it is 20-10 degreeC. The reaction time is usually 1 hour to 24 hours, preferably 1 hour to 12 hours.

  After completion of the reaction of Formula 3, if desired, the reaction solution is dropped into a large amount of alcohol to precipitate polyamide, which is filtered off as a solid and washed with alcohol. As this alcohol, methanol, ethanol, propanol, butanol and the like can be used.

Since the silyl group is eliminated during the reaction in the step (i) or during the post-reaction treatment, the polyamide synthesized in the step (i) has almost no solubility in an organic solvent. Therefore, it cannot be cast into a film by dissolving it in an organic solvent. Therefore, in order to increase the solubility in a general organic solvent, in step (ii), at least some of the hydroxy groups in the polyamide synthesized in step (i) are tert-butoxycarbonyl groups (also referred to as t-Boc groups). To obtain a substituted polyamide (see Formula 4 below). Specifically, this step can be performed by reacting the polyamide synthesized in step (i) with di-tert-butyl dicarbonate in an organic solvent in the presence of a basic substance.

  As an organic solvent in the reaction of Formula 4, dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide, pyridine, tetrahydrofuran, 1,4-dioxane, toluene, benzene, pyridine, anisole, etc. should be used. Can do. As the basic substance, sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, triethylamine, trimethylamine, ammonia and the like can be used. The reaction temperature is usually 0-50 ° C, preferably 0-35 ° C. The reaction time is usually 0.5 hours to 50 hours, preferably 0.5 hours to 30 hours.

  After completion of the reaction of Formula 4, if desired, the reaction solution is dropped into water or alcohol to precipitate a substituted polyamide, filtered as a solid, and washed well with water or alcohol to purify the substituted polyamide. As this alcohol, methanol, ethanol, propanol, butanol and the like can be used.

The polybenzoxazole film of the present invention can be produced from the substituted polyamide of the present invention obtained by the above production method by a production method including the following steps:
(I) a step of obtaining a polyamide film by casting a solution obtained by dissolving the substituted polyamide of the present invention in an organic solvent; and (ii) a step of heating the polyamide film to cyclize to obtain a polybenzoxazole film.

  As the organic solvent in the step (i), general-purpose organic solvents such as dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide and the like can be used. The density | concentration of the substituted polyamide in a solution will not be specifically limited if it is a density | concentration suitable for cast film formation, Usually, it is 1 mg / ml-50 mg / ml, Preferably it is 1 mg / ml-30 mg / ml.

  The solution used for casting can be prepared by dissolving the purified substituted polyamide of the present invention in an organic solvent, but in the method for producing the substituted polyamide of the present invention, no purification treatment is performed after tert-butoxycarbonyl substitution. In this case, the reaction solution after the substitution reaction can be used as it is or after diluting to a necessary concentration by adding an organic solvent as necessary. In the latter case, there is an advantage that the process can be omitted and it is economical. In the latter case, since the organic solvent used in the substitution reaction becomes the solvent of the solution used for casting as it is, it is preferable to use dimethylformamide or N-methyl-2-pyrrolidone as the organic solvent.

  In step (i), the solution thus prepared is cast to obtain a polyamide film. This step can be performed by any conventionally known method. For example, the solution is cast on a substrate made of a material such as glass, fluororesin, aluminum, iron, or stainless steel, a sheet, a film, etc. Alternatively, a method of removing the organic solvent by heating under reduced pressure and a method of extruding the solution from a die and taking it up on a roll or an endless belt can be exemplified.

Next, the polyamide film thus obtained is heated and closed in step (ii) to obtain a polybenzoxazole film (see the following formula 5).

  In the step (ii), the heat treatment is preferably performed at 170 to 400 ° C, more preferably 200 to 400 ° C. If the heat treatment temperature is higher than the upper limit, side reactions may occur, and mechanical properties and the like may be reduced. On the other hand, when the heat treatment temperature is lower than the lower limit, the ring closure reaction becomes extremely slow, and the target polybenzoxazole film may not be obtained. The time for the heat treatment is usually 1 minute to 180 minutes, preferably 10 minutes to 150 minutes. Note that the heat treatment is preferably performed in an inert gas atmosphere because there is little decrease in mechanical properties due to side reactions.

  The polybenzoxazole film of the present invention produced as described above has a good balance of mechanical properties (particularly strength) in the longitudinal and lateral directions of the film, and has a high resistance to tearing from all directions. Therefore, the polybenzoxazole film of the present invention is a film for magnetic recording, an electronic circuit board, a substrate for mounting electronic components, a composite material reinforcing material, a structural surface protective film, a flame retardant heat resistant wire coating material for spacecraft and aircraft. They can be widely used as window materials for high-temperature containers, optical control materials, and the like.

  Next, a method for producing polybenzoxazole in which the carbon nanotubes of the present invention are uniformly dispersed will be described.

The method for producing polybenzoxazole in which the carbon nanotubes of the present invention are uniformly dispersed includes the following steps (i) to (ii):
(I) adding carbon nanotubes to a solution of the above substituted polyamide in an organic solvent and dispersing the carbon nanotubes to prepare a dispersion; and (ii) heating the dispersion to close the ring, A step of obtaining polybenzoxazole in which is uniformly dispersed.

  First, in step (i), carbon nanotubes are added to a solution in which the above substituted polyamide is dissolved in an organic solvent, and the carbon nanotubes are dispersed to prepare a dispersion.

  As the organic solvent in the step (i), general-purpose organic solvents such as dimethylformamide, N-methyl-2-pyrrolidone, N, N-dimethylacetamide and the like can be used. The concentration of the substituted polyamide in the solution is not particularly limited as long as it is a concentration suitable for subsequent molding, and is usually 1 mg / ml to 50 mg / ml, preferably 1 mg / ml to 30 mg / ml.

  A solution in which the substituted polyamide is dissolved in an organic solvent can be prepared by dissolving the purified substituted polyamide in an organic solvent. However, in the production of the substituted polyamide, the purification treatment is not performed after tert-butoxycarbonyl substitution. The reaction solution after the substitution reaction can be used as it is or after diluting to a required concentration by adding an organic solvent as necessary. In the latter case, there is an advantage that the process can be omitted and it is economical. In the latter case, the organic solvent used in the substitution reaction is directly used as the solvent of the solution in step (i). Therefore, N, N-dimethylformamide or N-methyl-2-pyrrolidone is used as the organic solvent. It is preferable.

  Next, carbon nanotubes are added to this solution, and the carbon nanotubes are dispersed to prepare a dispersion. The amount of carbon nanotubes added is preferably 0.01 to 10% by weight, more preferably 0.05 to 1% by weight, based on the polyamide before substitution with a tert-butoxycarbonyl group. The carbon nanotubes used here may be single-walled, double-walled, or multi-walled. The diameter of the carbon nanotube is preferably 0.5 to 100 nm, and more preferably 0.7 to 50 nm. The length of the carbon nanotube is preferably 0.5 to 200 μm, and more preferably 0.7 to 150 μm. The dispersion of the carbon nanotubes can be performed, for example, by irradiating the solution with ultrasonic waves. As the ultrasonic irradiation device, either a bus type or a probe type may be used.

Next, the dispersion prepared in this manner is formed into a desired shape such as a fiber shape if necessary, and then heated and closed in step (ii) to obtain polybenzoxazole in which carbon nanotubes are uniformly dispersed. (See Equation 5 below).

  In the step (ii), the heat treatment is preferably performed at 170 to 400 ° C, more preferably 200 to 400 ° C. If the heat treatment temperature is higher than the upper limit, side reactions may occur, and mechanical properties and the like may be reduced. On the other hand, when the heat treatment temperature is lower than the lower limit, the ring closure reaction becomes extremely slow, and the target polybenzoxazole may not be obtained. The time for the heat treatment is usually 1 minute to 180 minutes, preferably 10 minutes to 150 minutes. Note that the heat treatment is preferably performed in an inert gas atmosphere because there is little decrease in mechanical properties due to side reactions.

  As described above, polybenzoxazole in which carbon nanotubes are uniformly dispersed can be easily produced.

Next, the manufacturing method of the polybenzoxazole film which disperse | distributed the carbon nanotube of this invention uniformly is demonstrated. A method for producing a polybenzoxazole film in which carbon nanotubes of the present invention are uniformly dispersed includes the following steps (i) to (iii):
(I) adding carbon nanotubes to a solution of the above substituted polyamide in an organic solvent and dispersing the carbon nanotubes to prepare a dispersion;
(Ii) a step of obtaining a polyamide film in which the carbon nanotubes are uniformly dispersed by casting the dispersion; and (iii) heating the polyamide film to close the ring to obtain a polybenzoxazole film in which the carbon nanotubes are uniformly dispersed. Obtaining step.

  Of the above steps (i) to (iii), step (i) is the same as the method for producing polybenzoxazole of the present invention already described, and therefore description thereof is omitted here.

  In step (ii), the dispersion prepared in step (i) is cast to obtain a polyamide film. This step can be performed by any conventionally known method. For example, the dispersion is cast on a substrate made of a material such as glass, fluororesin, aluminum, iron, or stainless steel, a sheet, a film, and the like. Examples thereof include a method in which the organic solvent is removed by heating under pressure or reduced pressure, and a method in which the dispersion is extruded from a die and taken up on a roll or an endless belt.

Next, the polyamide film thus obtained is heated and closed in step (iii) to obtain a polybenzoxazole film (see Formula 5 below).

  In the step (iii), the heat treatment is preferably performed at 170 to 400 ° C, more preferably 200 to 400 ° C. If the heat treatment temperature is higher than the upper limit, side reactions may occur, and mechanical properties and the like may be reduced. On the other hand, when the heat treatment temperature is lower than the lower limit, the ring closure reaction becomes extremely slow, and the target polybenzoxazole film may not be obtained. The time for the heat treatment is usually 1 minute to 180 minutes, preferably 10 minutes to 150 minutes. Note that the heat treatment is preferably performed in an inert gas atmosphere because there is little decrease in mechanical properties due to side reactions.

  As described above, a polybenzoxazole film in which carbon nanotubes are uniformly dispersed can be easily produced.

  The polybenzoxazole and the film thus produced have uniformly dispersed carbon nanotubes, so that the light resistance that has been a drawback of polybenzoxazole is improved, and further, strength, electrical conductivity, heat It is thought that conductivity is also improved. Therefore, the polybenzoxazole obtained by the production method of the present invention and its film are a magnetic recording film, an electronic circuit board, a substrate for mounting electronic components, a composite material reinforcing material, a structural surface protective film, a spacecraft and an aircraft. It can be widely used as a flame retardant heat resistant wire coating material, a window material for a high temperature container, an optical control material, and the like.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, intrinsic viscosity, TGA, ¹ H-NMR and infrared absorption spectrum were measured as follows.

(1) Intrinsic viscosity A solution having a polymer concentration of 0.5 g / dl was prepared using concentrated sulfuric acid as a solvent, and the solution was measured at 30 ° C.
(2) TGA
Using an EXSTAR TG / DTA 6300 manufactured by SII, the thermogravimetric decrease was measured in a nitrogen atmosphere under a temperature rising rate of 10 ° C./min.
(3) ¹ H-NMR
The measurement was performed using ADVANCE 300 MHz manufactured by Bulker.
(4) Infrared absorption spectrum It measured using PROTEGE 460N made from Nicolet.
(5) Visible-Near Infrared (vis-NIR) absorption spectrum It measured using V-570 made from JASCO.
(6) Visible-Near Infrared Fluorescence Spectrum Measurement was performed at an excitation light wavelength of 500 to 850 nm and a detection wavelength of 900 to 1400 nm using Jobin Yvon manufactured by HORIBA.

[Reference example]
(1) Production of N, N ′, O, O′-tetra (trimethylsilyl) -4,6-diaminoresorcinol After the system was placed in a dry nitrogen atmosphere, 4,6-diaminoresorcinol dinitrogen was added to a 300 ml two-necked flask. 20.0 g (94.0 mmol) of hydrochloride, 100 ml of dehydrated toluene, 100 ml (370 mmol) of hexamethyldisilazane, and 15 ml (120 mmol) of chlorotrimethylsilane were added and reacted at 100 ° C. for 72 hours. After completion of the reaction, toluene, excess hexamethyldisilazane and chlorotrimethylsilane were removed under reduced pressure, and the residue was purified by distillation under reduced pressure. The formation of N, N ′, O, O′-tetra (trimethylsilyl) -4,6-diaminoresorcinol was confirmed by infrared absorption spectrum (FIG. 1) and ¹ H-NMR spectrum (FIG. 2). The boiling point of the product was 146-149 ° C./0.9 mmHg, and the yield was 43.7 g (87%).

[Example 1]
Production of tert-butoxycarbonyl-substituted polyamide (1)
(I) 4.29 g (10 mmol) of N, N ′, O, O′-tetra (trimethylsilyl) -4,6-diaminoresorcinol produced in Reference Example and dehydration treatment in a 300 ml three-necked flask under a dry nitrogen atmosphere 20 ml of N-methyl-2-pyrrolidone prepared was added and dissolved at 0 ° C. Purified commercially available terephthalic acid chloride (2.03 g, 10 mmol) was added little by little and reacted at 0 ° C. for 6 hours. After completion of the reaction, the reaction solution was dropped into 1000 ml of methanol, and the precipitate was collected by filtration and washed with 100 ml of methanol. The inherent viscosity η _inc of the precipitate was 1.21 dL / g. The structure was identified by the infrared absorption spectrum (FIG. 3), and the formation of polyamide was confirmed.

(Ii) 0.48 g (2 mmol) of the polyamide synthesized in (i), 5 ml of N-methyl-2-pyrrolidone, and 3 ml (8 mmol) of triethylamine were added to a 50 ml two-necked flask under a nitrogen atmosphere. Then, 1.09 g (5 mmol) of di-tert-butyl dicarbonate was added and stirred at room temperature for 4 hours. After completion of the reaction, the reaction solution was dropped into 100 ml of water, and the precipitate was collected by filtration and washed with 20 ml of water. The structure was identified by infrared absorption spectrum (FIG. 4) and ¹ H-NMR spectrum (FIG. 5), and the production of tert-butoxycarbonyl-substituted polyamide was confirmed.

[Example 2]
Production of tert-butoxycarbonyl-substituted polyamide (2)
(I) 4.29 g (10 mmol) of N, N ′, O, O′-tetra (trimethylsilyl) -4,6-diaminoresorcinol produced in Reference Example and dehydration treatment in a 300 ml three-necked flask under a dry nitrogen atmosphere 20 ml of N-methyl-2-pyrrolidone prepared was added and dissolved at 0 ° C. Purified commercially available terephthalic acid chloride (2.03 g, 10 mmol) was added little by little and reacted at 0 ° C. for 6 hours.

(Ii) Next, 50 ml of N-methyl-2-pyrrolidone was added to the reaction solution, and the mixture was further stirred for 1 hour. To this reaction solution, 8.3 ml (60 mmol) of triethylamine and 9.2 ml (40 mmol) of di-tert-butyl dicarbonate were added, and the mixture was further reacted for 24 hours. After completion of the reaction, the reaction solution was dropped into 1000 ml of methanol, and the precipitate was collected by filtration and washed with 100 ml of methanol to obtain a tert-butoxycarbonyl-substituted polyamide. The yield was 3.7 g (83%).

[Example 3]
Production of polybenzoxazole film (i) 0.5 g of the tert-butoxycarbonyl-substituted polyamide produced in Example 2 was dissolved in 100 ml of N-methyl-2-pyrrolidone to prepare a casting solution. Cast on an aluminum plate. Then, the solvent was distilled off under an environment of 3 mmHg for 24 hours at room temperature and then 3 mmHg for 1 hour each at 100 ° C., 200 ° C. and 300 ° C. to obtain a polyamide film.

(Ii) Next, this polyamide film was heated together with the plate at 360 ° C. for 30 minutes under a nitrogen stream to convert the polyamide into polybenzoxazole, thereby obtaining a polybenzoxazole film. The infrared absorption spectrum of the obtained film is shown in FIG. FIG. 7 shows a TGA chart when the casting solution used in (i) is heated to 700 ° C. When the mechanical properties of the obtained polybenzoxazole film were examined, a sufficient balance was achieved in the longitudinal and lateral directions.

[Example 4]
(1) Preparation of Dispersion Liquid 0.5 g of tert-butoxycarbonyl substituted polyamide produced in (2) was dissolved in 100 ml of N-methyl-2-pyrrolidone. To this solution, 1 mg of Unipym Hipco SWCNT was added as a carbon nanotube, and using a BRANSON 5510 (47 kHz, 100 W) manufactured by Yamato, the carbon nanotubes were dispersed by irradiating ultrasonic waves for 10 hours while maintaining the bath temperature at 30 to 35 ° C. I let you. Thereafter, centrifugation was performed at 10,000 g for 1 hour, and the supernatant was used as a dispersion.

(2) Production of polybenzoxazole film in which carbon nanotubes are uniformly dispersed (i) The dispersion prepared in (1) was cast on an aluminum plate of 5 cm × 5 cm. Thereafter, the solvent was distilled off in an environment of 3 mmHg for 24 hours at room temperature and then 3 mmHg for 1 hour each at 100 ° C., 200 ° C. and 300 ° C. to obtain a polyamide film in which carbon nanotubes were uniformly dispersed.

(Ii) Next, this polyamide film was heated together with the plate at 360 ° C. for 30 minutes under a nitrogen stream to convert the polyamide into polybenzoxazole, thereby obtaining a polybenzoxazole film in which carbon nanotubes were uniformly dispersed. The infrared absorption spectrum of the obtained film is shown in FIG. FIG. 9 shows a TGA chart when the tert-butoxycarbonyl-substituted polyamide film produced in (i) is heated to 700 ° C. Further, the visible-near infrared absorption spectrum and the visible-near infrared fluorescence two-dimensional spectrum of the casting solution are shown in FIGS. 10 and 11, respectively. FIG. 10 shows van Hobe absorption based on the presence of carbon nanotubes as one molecule, and FIG. 11 shows a spot-like visible-near infrared fluorescence spectrum based on the presence of carbon nanotubes as one molecule. It can be seen. From these results, it can be seen that in the obtained polybenzoxazole film, the carbon nanotubes are unbundled and uniformly dispersed one by one. Furthermore, when the light resistance, strength, electrical conductivity, and thermal conductivity of the obtained polybenzoxazole film were examined, all were sufficiently high.

  When the substituted polyamide of the present invention is used, it is possible to easily produce a polybenzoxazole film in which the mechanical properties (particularly strength) in the machine direction and the transverse direction are balanced. Such polybenzoxazole films can be widely used in various fields including magnetic recording films. Further, according to the production method of the present invention, since carbon nanotubes are added at the stage of substituted polyamide which is a precursor of polybenzoxazole, polybenzoxazole in which carbon nanotubes are uniformly dispersed and a film thereof can be easily obtained. it can. Since such polybenzoxazole and its film are uniformly dispersed with carbon nanotubes, it has excellent light resistance, strength, electrical conductivity, and thermal conductivity, and is widely used in various fields including magnetic recording films. be able to.

Claims (5)

  A substituted polyamide which is a precursor of polybenzoxazole, wherein the polyamide has a hydroxy group in an ortho position relative to an amide group, and at least a part of the hydroxy group is substituted with a tert-butoxycarbonyl group. A substituted polyamide characterized by The process for producing a substituted polyamide according to claim 1, comprising the following steps:
(I) reacting silylated 4,6-diaminoresorcinol with terephthalic acid chloride to synthesize a polyamide having a hydroxy group in the ortho position relative to the amide group; and (ii) at least one of the synthesized polyamides A step of substituting part of the hydroxy group with a tert-butoxycarbonyl group to obtain a substituted polyamide. A method for producing a polybenzoxazole film comprising the following steps:
(I) a step of obtaining a polyamide film by casting a solution in which the substituted polyamide according to claim 1 is dissolved in an organic solvent; and (ii) a step of heating and ring-closing the polyamide film to obtain a polybenzoxazole film. A method for producing polybenzoxazole in which carbon nanotubes are uniformly dispersed, comprising the following steps:
(I) adding carbon nanotubes to a solution of the substituted polyamide according to claim 1 dissolved in an organic solvent and dispersing the carbon nanotubes to prepare a dispersion; and (ii) heating the dispersion to cyclize And obtaining polybenzoxazole in which carbon nanotubes are uniformly dispersed. A method for producing a polybenzoxazole film in which carbon nanotubes are uniformly dispersed, comprising the following steps:
(I) adding carbon nanotubes to a solution of the substituted polyamide according to claim 1 dissolved in an organic solvent, and dispersing the carbon nanotubes to prepare a dispersion;
(Ii) a step of obtaining a polyamide film in which the carbon nanotubes are uniformly dispersed by casting the dispersion; and (iii) heating the polyamide film to close the ring to obtain a polybenzoxazole film in which the carbon nanotubes are uniformly dispersed. Obtaining step.