JPH0355493B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to improved polyparaphenylene terephthalamide (hereinafter abbreviated as PPTA), and more specifically, to a molded product obtained by molding an optically anisotropic dope thereof. This relates to PPTA in which the amount of amine terminal groups and the amount of carboxylic acid terminal groups in the polymer are reduced in order to reduce moisture absorption. [Prior art] PPTA, which is obtained by polymerizing terephthalic acid dichloride (hereinafter abbreviated as TPC) and paraphenylenediamine (hereinafter abbreviated as PDA), has excellent mechanical properties because it has a rigid molecular skeleton. It has been predicted for a long time that molded products will be produced, and it has actually been reported that
Since the method for producing high-strength fibers was disclosed by Yasuda Blaze (Japanese Patent Application Laid-open No. 47-39458),
Due to its excellent mechanical properties and heat resistance, PPTA fiber has attracted particular attention in recent years as an industrial material such as tire cords and reinforcing materials for FRP. In addition, PPTA film is attracting attention as a promising material in industrial fields that require high mechanical properties, such as base films for magnetic tapes, and several methods for manufacturing PPTA film have been disclosed (for example,
57-17886). It is known that PPTA can be produced by low-temperature solution polymerization in an amide-based polar solvent (for example, Japanese Patent Application Laid-Open No. 100496/1983). , because it has an amide bond produced by dehydrochloric acid condensation of monomers and a hydrophilic group such as an amine terminal group and a carboxylic acid terminal group as the molecular chain terminal group at the end of polymerization, it is possible to mold it using such ordinary PPTA. Molded products tend to absorb moisture, and therefore have drawbacks such as changes in dimensions, decreases in strength and modulus of elasticity, and fluctuations in electrical properties due to moisture absorption. [Problems to be Solved by the Invention] It is an object of the present invention to have good moldability and mechanical and thermal properties of the obtained molded product, not to exhibit the above-mentioned drawbacks due to moisture absorption, and to be able to withstand high temperatures and high temperatures. Excellent dimensional stability and excellent mechanical properties even under harsh temperature conditions.
The object of the present invention is to provide a PPTA polymer suitable for obtaining a PPTA molded product having good electrical properties. [Means for Solving the Problems] As mentioned above, PPTA obtained by polymerizing TPC and PDA has molecular chain ends consisting of an amine end group and a carboxylic acid end group. As we continued to study the relationship between various PPTA polymers with different compositions and the rate of dimensional change due to moisture absorption, that is, the rate of dimensional change due to moisture absorption of molded products obtained by molding them, we found that We discovered the surprising phenomenon that as the amount of both amine and carboxylic acid end groups per unit weight of polymer decreases by capping with substituents, the hygroscopic dimensional change rate of molded products prepared using this decreases. As a result of further intensive research, the present invention has been completed. In other words, in the present invention, ηinh is 3.0 or more,
The apparent density is 1.38 g/cm ³ or less, the amine end group is 80−10×(ηinh) milliequivalents/Kg or less,
The present invention also provides PPTA, which is characterized in that the carboxylic acid terminal group is 80−10×(ηinh) milliequivalents/Kg or less. The polymer of the present invention is as follows: This is a PPTA with a repeating unit, but it must meet the requirements described below. In other words, if the degree of polymerization of the PPTA of the present invention is too low, it will not be possible to obtain a molded product having the excellent mechanical properties inherent to PPTA, so polymerization should be carried out to give an logarithmic viscosity (ηinh) of usually 3.0 or more, preferably 3.5 or more. The degree is selected. The polymers of the present invention have a density of less than 1.38 g/cm ³ , preferably less than 1.36 g/cm ³ . Polymers with high density generally have high crystallinity, and such polymers have poor solubility in concentrated sulfuric acid during dope preparation, resulting in an uneven dope, undissolved polymer remaining, and problems with dissolution. As the time required increases, the degree of decrease in molecular weight increases due to decomposition of the polymer, which adversely affects the moldability and physical properties of the molded product, which is not preferable. Furthermore, the polymer of the present invention must also satisfy the following conditions regarding its terminal groups. That is, the amount of amine end groups is 80×10×(ηinh) milliequivalents/Kg or less (preferably 70−10×(ηinh) milliequivalents/Kg or less) and the amount of carboxylic acid end groups is 80−10 milliequivalents/Kg or less.
× (ηinh) milliequivalent/Kg or less (preferably 70−10
x (ηinh) milliequivalents/Kg or less). The hygroscopicity of a PPTA molded product has a close relationship with the amount of end groups, and if a polymer with a terminal group outside this range is used, the hygroscopicity of the resulting molded product cannot be sufficiently reduced. This is because mechanical properties tend to deteriorate and electrical properties such as electrical insulation properties tend to fluctuate. [Action of the Invention] The reason for the decrease in hygroscopicity due to the decrease in the amount of amine and carboxylic acid terminal groups is not clear, but it can be considered as follows. Molded polymers, no matter how PPTA, cannot be completely crystalline and have a certain amount of amorphous parts, and it is thought that most of the molecular chain ends exist in these amorphous parts. . On the other hand, when moisture infiltrates into the molded product, it is selectively taken in from the amorphous portion. Therefore, it is thought that hygroscopicity decreases due to a decrease in polar end groups that have a strong affinity for water. Therefore, it is also effective and a preferred embodiment to heat-treat a molded article obtained using the polymer of the present invention within a range that does not cause deterioration of the polymer, thereby making it even more difficult to absorb moisture. By the way, the total amount of end groups in a given weight of polymer is inversely proportional to the number average molecular weight of that polymer, and some researchers have also found that the relationship between the viscosity of a concentrated sulfuric acid solution of PPTA and the number average molecular weight is (For example, M. Arpin Dei Macromolecule Hemy, Vol. 177 ,
No. 581 (1976)). According to that knowledge, TPC and
When PDA is polymerized stoichiometrically, when ηinh is 5, its number average molecular weight is approximately 20,000,
There are 2 end groups in 20000 g of polymer.
In other words, there are approximately 100 milliequivalents of end groups in 1 kg of polymer, and 50 milliequivalents each of amine and carboxylic acid ends, assuming a perfectly balanced monomer charge and no other termination reactions. There must be a group. When ηinh is 6, the number average molecular weight is approximately 24,000, and approximately 40 milliequivalents of amine and carboxylic acid end groups are present per 1 kg of polymer. Comparing these numbers, it is clear that the polymers of the present invention have very low amounts of both amine and carboxylic acid end groups. Up until now, the composition of TPC and PDA has been studied regarding the production technology of PPTA polymer, but the main focus has been on increasing the molecular weight of the resulting polymer, and the charging ratio of TPC and PDA has been studied. There are few examples that focus on the terminal group of the molecular chain. during polymerization
Although a spinning method using a polymer with an excessively large number of amine end groups by manipulating the molar balance of TPC and PDA has been disclosed (US Pat. No. 3,933,963),
This is also intended only to improve spinnability, and there is no precedent for technology that attempts to improve the physical properties of molded products by actively manipulating the molecular chain terminal groups, as in the present invention. However, the PPTA polymer of the present invention cannot be obtained by these known techniques. Next, an example of a method for producing the polymer of the present invention will be shown. When PPTA with few amine end groups and carboxylic acid end groups is prepared by the reaction of PDA and TPC using a so-called low-temperature solution polymerization method,
Reactive with amines or carboxylic acid chlorides. It can be produced by adding one or more substances other than TPC and PDA and reacting with the terminal amine or terminal carboxylic acid chloride to block the molecular chain ends. The substance to be added is not particularly limited and may be any substance as long as it is reactive with the amine or carboxylic acid chloride as described above. Examples of substances to be added include aniline, o-, m- or p-
- Chloraniline, o-, m- or p-toluidine, o-, m- or p-nitroaniline, α- or β-naphthylamine, 2-,3
- or monoprimary amines such as 4-biphenylamine, ethylamine, propylamine, isopropylamine, cyclohexylamine, secondary monoamines such as N-methylaniline, diethylamine, piperidine, or benzoyl chloride, o-, m- or p- Monocarboxylic acid chlorides such as toluoyl chloride, propionyl chloride, and cyclohexane carbonyl chloride, or phenyl isocyanate, ethyl isocyanate, phenyl isothiocyanate, and ethyl isothiocyanate are used. In addition, in order to make the effect of such terminal blocking even more remarkable, it is also a useful embodiment to use, for example, a compound in which one or more of the hydrogen atoms in the above compound is substituted with fluorine. be. Furthermore, the method of adding and reacting these substances is not particularly limited. For example, in a known polymerization method (for example, Japanese Patent Application Laid-Open No. 54-100496), they may be added and reacted at any time during polymerization. or once polymerized,
They may be impregnated and reacted in a suitable solvent. A more specific example of a method for producing the polymer of the present invention is shown below. However, it goes without saying that the method for producing the polymer (polymerization method) of the present invention is not limited to the method shown below. Polymerization is most easily carried out by a so-called low-temperature solution polymerization method in which TPC and PDA are stirred and mixed in an amide solvent. As a solvent in polymerization, N-
Methylpyrrolidone, N,N-dimethylacetamide, N-acetylpyrrolidine, tetramethylurea, hexamethylphosphoramide, etc., or mixtures thereof in arbitrary proportions, or mixtures of these with lithium chloride, calcium chloride, etc. are used. The monomer concentration during polymerization is approximately 0.1 to 1.0 mol/
It is. In the conventional PPTA polymerization method, TPC and PDA are charged in a ratio of approximately 1:1 and mixed with stirring in the solvent, but special measures are required to obtain the polymer of the present invention. For example, TPC and
Adjust the molar balance of PDA so that TPC is in excess (the degree is that when PDA is 100, TPC is
Approximately 100.0 to 101 is preferable. This is because if the molar balance is disturbed too much, the molecular weight cannot be made sufficiently high. ) At the time of monomer preparation, one or more of the above-mentioned monoamines,
They are added so that the overall ratio of amino groups to carboxylic acid chloride groups is approximately 1:1. As a result, the carboxylic acid ends are blocked, making it possible to obtain PPTA with fewer amine and carboxylic acid ends than polymers obtained by conventional methods. Of course, it is also possible to reverse the molar balance of TPC and PDA to the above and use a monocarboxylic acid chloride compound or the like as an end-capping agent. The amount of end-capping agent to be added should be adjusted to equalize the molar balance of acid chloride groups and amino groups.
(or PDA) 0.1 to 1.0 is appropriate for 100. In addition, in the polymer obtained by polymerization, the ratio of terminal groups to all monomers is ηinh.
When ηinh is 3.0, it is approximately 0.7%, and when ηinh is 5.0, it is approximately
Since it is 0.5%, from this reason as well, the above ratio is appropriate. Add a sealant when polymerization has progressed to a certain extent,
It is also possible to react. As the polymerization progresses, the generated PPTA may precipitate from the solvent, so in this case the reaction with the sealant becomes a heterogeneous reaction. Therefore, when adding a capping agent during polymerization, the probability of reaction between the capping agent and the amino group (or carboxylic acid chloride group) is increased.
For effective sealing, it is best to use an excess amount of sealant. Preferably, the amount is 5 to 10 times the amount required to equalize the molar balance of amino groups and carboxylic acid chloride groups. However, if the amount is too excessive, the progress of the subsequent polymerization will be inhibited, which is not preferable. The polymerization temperature is selected between about -30°C and 100°C.
During polymerization, it is preferable to stir the entire system, and more preferably to continue stirring even after the polymer has solidified until the final degree of polymerization is reached. The polymer that has reached the final degree of polymerization is, for example, transferred to a Henschel mixer, pulverized by adding approximately the same amount of water, washed several times with water, filtered or centrifuged, and dried. It is obtained as a pale yellow polymer. As a special method for producing PPTA of the present invention, after isolating a polymer polymerized in the same manner as before, terminal capping is performed by reacting it with a monoisocyanate, monocarboxylic acid chloride, monoaliphatic amine, etc. in a solid phase. is also possible. The logarithmic viscosity (ηinh) of the PPTA thus obtained is defined as follows. ηinh=l nηrel/0.5 where ηrel is the polymer solution (96% by weight sulfuric acid 100%
0.5 g PPTA in ml) and pure solvent, measured in a capillary viscometer at 25°C. Next, a method for quantifying terminal groups in the present invention will be explained. Amine end group determination method: Weigh 0.2 g of dried polymer into a 400 ml flat bottom flask and add 25 ml of ion exchange water. To this are added 0.2 g of sodium hydrogen carbonate and 25 ml of ethanol, and further 1.25 g of 1-fluoro-2,4-dinitrobenzene. A Dimroth condenser was attached to this flask, and the contents of the flask were stirred with a magnetic stirrer and refluxed for 4 hours in a water bath maintained at 80°C. The reddish-brown colored polymer is filtered and washed thoroughly with acetone. The polymer is then dried under reduced pressure at 80°C for 4 hours. Weigh 0.025 g of the polymer thus obtained into a 5.0 ml beaker, add 25 ml of methanesulfonic acid, and stir with a magnetic stirrer at room temperature until completely dissolved. At this time, seal the mouth of the beaker with a suitable sealant and keep it out of light as much as possible during the melting process. This is because the dinitrobenzene group has high photoreactivity and to avoid darkening due to exposure to light.
The transmittance of this solution at a wavelength of 430 nm is measured using a spectrophotometer (the device used by the present inventors is an absorption photometer model 6B manufactured by Hirama Rika Kenkyusho) using a quartz cell with an optical path length of 1 cm. At this time, polymer 1
The amount of amine end groups per kg is given by log T ₀ /T ₁ /ε×10 ⁶ meq/Kg. However, T ₀ is 0.025 g of untreated PPTA when the transmittance of methanesulfonic acid is 100%.
ml, _T1 is the transmittance of a methanesulfonic acid solution of PPTA treated as described above, when the transmittance of methanesulfonic acid is taken as 100%, and ε is the transmittance of a methanesulfonic acid solution of PPTA treated as described above. The molar extinction coefficient of the dinitrobenzene group measured using a model compound, and the value is
7100 (/mol・cm). Method for quantifying carboxylic acid end groups To quantify carboxylic acid end groups, first wash the polymer thoroughly with water to make sure that no free acid or alkali remains in the polymer. To confirm this, the polymer is dispersed in an appropriate amount of water, heated and stirred at about 50°C, the polymer is filtered off, and the filtrate is titrated with an alkali or acid such as caustic soda or hydrochloric acid. The washed polymer is thoroughly dried, and the carboxylic acid end groups are quantified by the following method. Weigh 0.2 g of the dried polymer into a flat-bottomed flask and add 25 ml of 10 ^-3 normal sodium hydroxide solution (1:1 water-ethanol solution). A Dimroth condenser was attached to the flask, and the mixture was refluxed for 4 hours in a water bath kept at 80°C while stirring with a magnetic stirrer. The polymer is separated by filtration, washed with a small amount of ethanol, this washing liquid is combined with the previous filtrate, and this is titrated with a 10 ^-3 N aqueous hydrochloric acid solution. At this time, the amount of 10 ^-3 normal hydrochloric acid aqueous solution required for neutralization is
V: ₁ ml. In addition, using the same procedure, reflux only the 10 ^-3 N sodium hydroxide solution, then titrate with a 10 ^-3 N aqueous hydrochloric acid solution, and assuming that the amount of the aqueous hydrochloric acid solution required for neutralization is V ₀ ml, the desired carboxylic acid The amount of terminal groups is V ₀ −V ₁ /0.2 milliequivalent/Kg per 1Kg of polymer. Incidentally, the entire process for quantifying the carboxylic acid terminal group is carried out in an inert gas atmosphere in order to avoid absorption of carbon dioxide gas from the atmosphere. When actually molding using the polymer of the present invention, a known PPTA molding method, i.e.
A method of molding from an optically anisotropic dope made of PPTA, concentrated sulfuric acid, etc. can be used. In addition to sulfuric acid, chlorosulfuric acid, fluorosulfuric acid, or a mixture of these and sulfuric acid can be used as the solvent for preparing the dope, but in terms of solubility,
Concentrated sulfuric acid of 96% by weight or more is preferred. The polymer concentration is at least a concentration that exhibits optical anisotropy at room temperature or higher temperatures. Specifically, about 10% by weight or more,
Preferably it is 15% by weight or more. This is because molded products made from optically isotropic dopes generally have low density and low strength, making it difficult to exhibit the high mechanical properties inherent to PPTA. Dopes with such polymer concentrations often need to be slightly warmed to allow them to flow and be molded; however, higher temperatures increase the rate of deterioration, so dopes with temperatures ranging from room temperature to 100°C are usually used. be done. The dope may also contain conventional additives such as antioxidants and ultraviolet stabilizers. In producing PPTA fibers from such dope, for example, the method described in Japanese Patent Application Laid-Open No. 47-39458 can be used. Also
For the production of PPTA film, for example, the method disclosed in Japanese Patent Publication No. 17886/1986 can be used, but the method is not limited thereto. [Example] The present invention will be further explained by the following example. It goes without saying that these examples are illustrative of the invention and are not intended to limit it. Example 1 70 parts of calcium chloride was dissolved in 1000 parts of N-methylpyrrolidone in a polymerization tank equipped with a stirring blade rotating at high speed, an inlet and an inlet for dry nitrogen, and an inlet for raw materials.
44.2 parts of PDA (equivalent to 0.4 mol per 1 solvent) and 0.4 part of aniline (equivalent to 1 mol % relative to PDA) were dissolved. After cooling to -2℃, 85.1 parts of TPC (PDA)
(equivalent to 101 mol%) was added at once in a molten state. After 3 minutes, the polymer solidified into a cheese-like shape, so the polymerization reaction product was immediately transferred to a twin-screw closed kneader, and pulverized and subjected to shearing force in the same kneader for 20 minutes. Next, the pulverized polymer was transferred to a Henschel mixer, and approximately the same amount of water was added thereto for further pulverization, followed by filtration, washing with hot water several times, and drying in hot air at 110°C. As a result, 95 parts of pale yellow PPTA with an ηinh of 4.3 and an apparent density of 1.35 g/cm ³ was obtained. The results of measuring the amount of terminal groups using the method described above were as follows. Amine terminal group amount: 31.3 milliequivalents/Kg, carboxylic acid terminal group amount: 25.9 milliequivalents/Kg Next, using this polymer, a film was formed by the following method. Pour 88 parts of 99.6% sulfuric acid into a 500 ml separable flask, add 12 parts of the above polymer in two portions, and add the dope with stirring over a total of 40 minutes (at room temperature) and continue stirring for another 10 minutes. After setting the temperature
The temperature was raised to 60°C and defoaming was performed for 5 hours to prepare an optically anisotropic dope. This dope was placed on a glass plate preheated to 120°C, and a film was formed manually using an ablator with a 0.1 mm slit. Do this immediately
It was placed in hot air maintained at 120°C and left for 10 minutes to perform isotropic treatment based on optical anisotropy. After that, the film was immersed together with the glass plate in pure water to deoxidize it.
The film was peeled off. This wet film was sandwiched between metal frames and dried in hot air at 250℃ for an hour to reduce the thickness.
A yellow transparent film of 25 μm was obtained. The moisture absorption dimensional change rate of the obtained film was measured by the following method. After drying the sample at 100℃ under a nitrogen stream and cooling it to room temperature, it was measured using a TMA (thermomechanical measuring device, TMA-30 manufactured by Shimadzu Corporation) in an atmosphere with relative humidity of 85%.
The elongation of the sample was measured and calculated using the following formula. Moisture absorption dimensional change rate (mm/mm・%RH) Elongation of sample (mm)/original length of sample (mm) x 85 (%)
RH) The size of the sample at the time of measurement was 2 mm in width and 8 mm in effective grip distance. As a result, the moisture absorption dimensional change rate of the above film was 3.9×10 ^-5 mm/mm・%RH in the longitudinal direction and 6.5×10 ⁻⁵ mm/mm・%RH in the width direction. Example 2 The same polymer as in Example 1 was added at a ratio of 12 parts to 88 parts of 99.7% sulfuric acid to prepare an optically anisotropic dope at 65°C. The 1.5m curved pipe from the dope tank to the die via the gear pump is maintained at 65℃, and the temperature of 0.1
From a die with a slit of mm x 300 mm, a tantalum belt with a mirror-polished
Cast at a speed of m/min, relative humidity 73%, temperature
After being exposed to air at 36°C for 60 seconds and the dope becoming transparent, it was coagulated in water at 10°C. This coagulated film was washed with water at room temperature overnight and then dried with hot air at 250° C. for 1 hour to obtain a transparent yellow film with a thickness of 20 μm. Table 1 shows the physical properties of the obtained film. Comparative Example 1 In a polymerization tank, 70 parts of calcium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then 44.2 parts of PDA was dissolved.
part (equivalent to 0.4 mol per 1 solvent) was dissolved. -2
After cooling to ℃, 85.1 parts of TPC (equivalent to 0.4 mol per solvent) was added at once, and then polymerization was carried out under the same conditions as in Example 1, and ηinh was 4.6.
A pale yellow PPTA with an apparent density of 1.35 g/cm ³ was obtained. The amount of terminal groups of the obtained polymer was as follows. Amount of amine terminal groups: 47.3 milliequivalents/Kg Amount of carboxylic acid terminal groups: 35.9 milliequivalents/Kg Using this polymer, a film was prepared in the same manner as in Example 1, and the dimensional change rate upon moisture absorption was measured. The results are as follows. , the dimensional stability was inferior to that of Example 1. Longitudinal direction 9.0×10 ^-5 mm/mm・%RH Width direction 10.8×10 ⁻⁵ mm/mm・%RH Comparative example 2 ηinh was
5.78, pale yellow PPTA with an apparent density of 1.37 g/cm ³ was obtained. The amount of end groups of this polymer was 40.5 meq/Kg for amine end groups and 32.1 meq/Kg for carboxylic acid end groups. This polymer was added at a ratio of 12 parts to 100 parts of 99.4% by weight sulfuric acid to obtain an optically anisotropic dope at 65°C. A film was formed from this dope under the same conditions as in Example 2 to obtain a yellow transparent film with a thickness of 15 μm. Table 1 shows the physical properties of the obtained film. Example 3 The same polymer as in Example 1 was added to 99.7% by weight sulfuric acid.
A dope exhibiting optical anisotropy at 70°C was prepared by gradually dissolving 19.3 parts in 80.1 parts. From the dope tank through the gear pump, the spinneret (pore diameter 0.07mmΦ-50) equipped with a 5μm SUS316 sintered filter
The piping leading to the hole) is heated to 70℃, and the discharge pressure is 50℃.
The dope was extruded from the nozzle at Kg/cm ² . After passing through a 5 mm air layer, the extruded dope is introduced into water at 0°C. From this coagulation bath, coagulation progresses while passing through a glass tube through which spinning water flows, and the peripheral speed is 200.
It was wound onto a bobbin that rotates at m/min. The obtained yarn was washed with running water overnight and then dried with hot air at 100°C to obtain a yellow yarn with a single yarn of 1.5 denier. The physical properties of the obtained yarn are shown in Table 2. During this spinning, there were no spinning troubles such as spinneret clogging or abnormal increase in spinneret pressure, and very stable spinnability was exhibited. Comparative Example 3 Using the same polymer as in Comparative Example 2, an optically anisotropic dope was prepared in the same manner as in Example 3, and spinning was performed under the same conditions. Table 2 shows the physical properties of the yarn thus obtained. Compared to the yarn of Example 3, the strength and elongation were slightly inferior, and the moisture absorption rate was high. Almost no trouble occurred during this spinning, but the spinneret pressure increased considerably. Example 4 In the same polymerization tank as in Example 1, 21 parts of lithium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then
44.6 parts of PDA (1 mol % excess with respect to TPC added later) was dissolved. After cooling to -2℃
84.3 parts of TPC (equivalent to 0.4 mol relative to solvent 1) was added in a molten state, and subsequently 0.6 part of benzoyl chloride (equivalent to 1 mol % relative to TPC) was added all at once in powder form. Since the polymer solidified in 2 to 3 minutes, the polymerization was carried out in the same manner as in Example 1. 96 parts of pale yellow PPTA with ηinh5.1 was obtained. The amount of end groups and apparent density of this polymer were as follows: amine end group amount: 25.1 meq/Kg, carboxylic acid end group amount: 22.7 meq/Kg, and apparent density: 1.36 g/cm ³ . A film was formed using this polymer in the same manner as in Example 1.
A yellow transparent film with a thickness of 23 μm was obtained. The moisture absorption dimensional change rate of this film was 3.7×10 ^-5 mm/mm・%RH in the longitudinal direction and 5.5×10 ⁻⁵ mm/mm・%RH in the width direction. Example 5 In the polymerization tank used in Example 1, 70 parts of calcium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then 44.6 parts of PDA were dissolved. After cooling to -2℃, 85.1 parts of TPC was added in a molten state at once.
Thereafter, polymerization was carried out under the same conditions as in Example 1. The yellow polymer obtained had an ηinh of 4.9, an apparent density of 1.36 g/cm ³ , and amine end groups of 45.1 meq/Kg and carboxylic acid end groups of 31.8 meq/Kg. 100 parts of this dried polymer was dispersed in tetrahydrofuran, 0.8 parts of phenyl isocyanate was added, and the mixture was stirred for 2 hours using a magnetic stirrer on a 25°C water bath. The polymer was filtered and dried, and the amount of end groups was quantified. As a result, PPTA was obtained with the following values: amine end group: 27.8 milliequivalents/Kg, carboxylic acid end group: 29.8 milliequivalents/Kg, with no change in ηinh or density. Using this polymer, an optically anisotropic dope was prepared in the same manner as in Example 1, and a film was formed to a thickness of 24 μm.
A yellow transparent film of m was obtained. The moisture absorption dimensional change rate of this film was 6.1×10 ^-5 mm/mm・%RH in the longitudinal direction and 7.3×10 ⁻⁵ mm/mm・%RH in the width direction. Example 6 In the same polymerization tank as in Example 1, 70 parts of calcium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then 44.2 parts of PDA (equivalent to 0.4 mol per 1 solvent) was dissolved. After cooling this solution to -2°C,
85.1 parts of TPC (equivalent to 101 mol % based on PDA) was added in a molten state all at once. After 3 minutes, the polymerization reaction product solidified into a cheese-like shape was transferred to a twin-screw closed kneader.
Immediately thereafter, a solution of 2 parts of aniline (5 mol % based on PDA) dissolved in 100 parts of N-methylpyrrolidone was added, and pulverization and shearing force were applied in the same kneader for 30 minutes. The pulverized polymer was transferred into a Henschel mixer, and approximately the same amount of water was added thereto for further pulverization, followed by washing several times with warm water and drying at 110°C. This gives ηinh4.1, apparent density
95 parts of PPTA of 1.36 g/cm ³ were obtained. The amount of terminal groups of this polymer was 28.3 meq/Kg of amine end groups and 25.6 meq/Kg of carboxylic acid end groups. Next, using this polymer, an optically anisotropic dope was prepared in the same manner as in Example 1, and a film was formed.
A yellow transparent film with a thickness of 20 μm was obtained. The moisture absorption dimensional change rate of the obtained film was 4.8×10 ^-5 mm/mm・%RH in the longitudinal direction and 6.6×10 ⁻⁵ mm/mm・%RH in the width direction. Example 7 In the same polymerization tank as in Example 1, 70 parts of calcium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then 44.6 parts of PDA (equivalent to 101 mol% based on TPC) was added.
was dissolved. After cooling this solution to -2°C,
84.3 parts of TPC (corresponding to 0.4 mol % per solvent) was added in a molten state all at once. After 2.5 minutes, the polymerization reaction product solidified into a cheese-like shape was transferred to a twin-screw closed kneader in the same manner as in Example 6, and immediately after that, 3 parts of benzoyl chloride (5 mol based on TPC) was added to 100 parts of N-methylpyrrolidone. %) was added, and pulverization and shearing force were applied for 30 minutes. The pulverized polymer was transferred into a Henschel mixer, and approximately the same amount of water was added thereto for further pulverization, followed by washing several times with warm water and drying at 110°C. This results in
93 parts of PPTA having an ηinh of 4.1 and an apparent density of 1.35 g/cm ³ was obtained. Further, the amount of terminal groups of this PPTA was as follows: amine terminal group amount: 22.8 milliequivalents/Kg; carboxylic acid terminal group amount: 26.1 milliequivalents/Kg. An optically anisotropic dope was prepared in the same manner as in Example 1, and the film obtained by manual film formation was as follows:
It was transparent yellow and had a thickness of 21 μm, and its moisture absorption dimensional change rate was 4.2×10 ^-5 mm/mm・%RH in the longitudinal direction and 6.1×10 ⁻⁵ mm/mm・%RH in the width direction. Example 8 In the same polymerization tank as in Example 1, 70 parts of calcium chloride were dissolved in 1000 parts of N-methylpyrrolidone, and then 44.2 parts of PDA (corresponding to 0.4 mol per 1 solvent) and 0.4 parts of octylamine (in PDA) were dissolved. (equivalent to 1 mol %) was dissolved. After cooling to -2℃, TPC81.6
(equivalent to 101 mol% based on PDA) was added at once in a molten state. After 3 minutes, the polymer solidified into a cheese-like shape, so this polymerization reaction product was immediately transferred to a twin-screw closed kneader, and pulverization and shearing force were applied in the same kneader for 20 minutes. Next, the pulverized polymer was transferred into a Henschel mixer, and approximately the same amount of water was added thereto for further pulverization, followed by filtration, washing with hot water several times, and drying in hot air at 110°C. the result,
Pale yellow with ηinh4.3 and apparent density 1.36g/ ^cm3 .
Obtained 95 copies of PPTA. The results of measuring the amount of terminal groups were as follows. Amine terminal group amount: 30.4 milliequivalents/Kg Carboxylic acid terminal group amount: 23.1 milliequivalents/Kg Furthermore, using this polymer, an optically anisotropic dope was prepared by the method of Example 1, and as a result of film formation, the thickness A yellow transparent film with a diameter of 25 μm was obtained. The moisture absorption dimensional change rate of the obtained film was as follows. Longitudinal direction 6.1×10 ^-5 mm/mm・%RH Width direction 6.9×10 ⁻⁵ mm/mm・%RH Example 9 In the same polymerization tank as in Example 1, 70 parts of calcium chloride was added to 1000 parts of N-methylpyrrolidone. Then, 44.2 parts of PDA (equivalent to 0.4 mol per solvent) and 0.4 part of cyclohexylamine (equivalent to 1 mol % based on PDA) were dissolved. After cooling to -2℃,
81.6 parts of TPC (equivalent to 101 mol % based on PDA) was added in a molten state all at once. After 3 minutes, the polymer solidified into a cheese-like shape, so this polymerization reaction product was immediately
The mixture was transferred to a closed-shaft kneader, and pulverization and shearing force were applied in the same kneader for 20 minutes. Next, the pulverized polymer was transferred into a Henschel mixer, and approximately the same amount of water was added thereto for further pulverization, followed by filtration, washing with hot water several times, and drying in hot air at 110°C. As a result, ηinh4.23, apparent density 1.36g/cm ³
Obtained 94 copies of PPTA. The amounts of terminal groups were as follows: Amino terminal group amount: 32.1 milliequivalents/Kg Carboxylic acid terminal group amount: 26.7 milliequivalents/Kg Using this PPTA, an optically anisotropic dope was prepared using the same method as in Example 1, and a film was formed. As a result, a film with a thickness of 23 μm was obtained, which had a moisture absorption dimensional change rate of 7.0×10 ⁻⁵ mm/mm%・RH in the longitudinal direction and 7.8×10 ⁻⁵ mm/mm%・RH in the width direction. Example 10 In the same polymerization tank as in Example 1, 70 parts of calcium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then 44.2 parts of PDA (corresponding to 0.4 mole per 1 solvent) and 0.5 parts of p-fluoroaniline ( (equivalent to 1 mol % based on PDA) was dissolved. After cooling to -2℃,
81.6 parts of TPC (equivalent to 101 mol % based on PDA) was added in a molten state all at once. After 3 minutes, the polymer solidified into a cheese-like shape, so this polymerization reaction product was immediately
The mixture was transferred to a closed-shaft kneader, and pulverization and shearing force were applied in the same kneader for 20 minutes. Next, the pulverized polymer was transferred into a Henschel mixer, and approximately the same amount of water was added thereto for further pulverization, followed by filtration, washing with hot water several times, and drying in hot air at 110°C. As a result, ηinh4.7, apparent density 1.36g/ ^cm3
Obtained 95 copies of PPTA. The results of measuring the amount of terminal groups were as follows: amino terminal group amount: 23.1 milliequivalents/Kg; carboxylic acid terminal group amount: 18.3 milliequivalents/Kg. Using this polymer, in the same manner as in Example 1,
As a result of preparing an optically anisotropic dope and manually forming a film,
A yellow transparent film with a thickness of 25 μm was obtained. The moisture absorption dimensional change rate of this film was as follows. Longitudinal direction 3.3×10 ^-5 mm/mm・%RH Width direction 4.3×10 ⁻⁵ mm/mm・%RH Example 11 In the same polymerization tank as in Example 1, 70 parts of calcium chloride was added to 1000 parts of N-methylpyrrolidone. was dissolved, and then 44.6 parts of PDA (1 mol % excess with respect to TPC added later) was dissolved. After cooling to -2℃
84.3 parts of TPC (equivalent to 0.4 mol relative to 1 solvent) was added in the melt, followed by 0.6 part of p-fluorobenzoyl chloride (1 mol % relative to TPC).
(equivalent) was added all at once in powder form. Since the polymer solidified in 2 to 3 minutes, the polymerization was carried out in the same manner as in Example 1 to obtain 95 parts of PPTA with an ηinh of 4.5. The amount of end groups and apparent density of this polymer were as follows: amine end group amount: 24.0 meq/Kg, carboxylic acid end group amount: 24.2 meq/Kg, and apparent density: 1.35 g/cm ³ . A film was formed using this polymer in the same manner as in Example 1 to obtain a yellow transparent film with a thickness of 23 μm. The moisture absorption dimensional change rate of this film was 5.7×10 ^-5 mm/mm・%RH in the longitudinal direction and 6.6×10 ⁻⁵ mm/mm・%RH in the width direction. Example 12 Using the same polymer as in Example 10, spinning was performed by the method of Example 3 to obtain a yellow filament with a single yarn denier of 1.5. During spinning, there were no problems such as spinneret clogging or abnormal increase in spinneret pressure, and the spinning performance was very stable. Table 3 shows the physical properties of this yarn and that of the yarn further heat-treated at 300° C. for 150 seconds. Example 13 In the same polymerization tank as in Example 1, 70 parts of calcium chloride were dissolved in 1000 parts of N-methylpyrrolidone, and then 44.2 parts of PDA (equivalent to 0.4 mole per 1 solvent) and 2,4,6-tripropylene were added. 0.6 part of fluoroaniline (equivalent to 1 mol % based on PDA) was dissolved. -2℃
After cooling to , 81.6 parts of TPC (equivalent to 101 mol % based on PDA) was added all at once in a molten state. After 3 minutes, the polymer solidified into a cheese-like shape, so this polymerization reaction product was immediately transferred to a twin-screw closed kneader, and pulverization and shearing force were applied in the same kneader for 20 minutes.
Next, the pulverized polymer was transferred to a Henschel mixer, and approximately the same amount of water was added thereto for further pulverization.
It was filtered, washed several times with warm water, and dried in hot air at 110°C. As a result, ηinh4.1, apparent density 1.35
95 parts of PPTA of g/cm ³ were obtained. The results of measuring the amount of terminal groups were as follows: amino terminal group amount: 32.5 milliequivalents/Kg; carboxylic acid terminal group amount: 24.6 milliequivalents/Kg. Using this polymer, an optically anisotropic dope was prepared in the same manner as in Example 1, and as a result of forming a film, the thickness was
A yellow transparent film of 23 μm was obtained. The moisture absorption dimensional change rate of this film was as follows. Longitudinal direction 3.2×10 ^-5 mm/mm・%RH Width direction 4.0×10 ⁻⁵ mm/mm・%RH

【table】

【table】

〔Effect of the invention〕

The PPTA of the present invention is characterized in that the amine or/and carboxylic acid terminals are capped with a hydrophobic substituent that is reactive with amines or carboxylic acid chlorides.
By using a molded product, the hygroscopicity of the obtained molded product is reduced, and the dimensional change rate due to moisture absorption (or water absorption) is reduced. This is caused by the end of the molecular chain being capped with a hydrophobic substituent. This is thought to be due to the fact that the amorphous parts of the molded product are made hydrophobic. In PPTA polymers with ηinh of 3 or more, the amount of terminal groups is approximately 1% or less of the total amide bonds, and until now there has been no phenomenon in which hygroscopicity is significantly reduced just by making a part of them hydrophobic. Although many researchers have continued to study PPTA, they have not been able to achieve it. Furthermore, as is clear from the examples, the present invention
Molded products obtained using PPTA not only exhibit excellent moisture absorption dimensional stability, but also exhibit a decrease in moisture absorption.
High mechanical properties can be stably achieved, moldability is improved as evidenced by the small increase in spinneret pressure, and PPTA's inherent heat resistance, chemical resistance, and electrical insulation properties are also improved. Due to these major improvements, molded products obtained using the PPTA of the present invention can be used in fields that require high dimensional accuracy, heat resistance, and mechanical properties, such as films for flexible printed wiring boards, base films for magnetic tapes, Alternatively, it can be preferably used for applications such as fibers for reinforcing optical fiber cables.
In addition, when plastics reinforced with PPTA fibers are used, for example, in aircraft parts, the temperature and humidity of the environment in which they are used fluctuates significantly and this is repeated, resulting in the PPTA fibers gradually absorbing moisture. It has been reported that plastics eventually crack due to dimensional changes, but even for such uses, the fibers obtained from the polymer of the present invention are very suitable as fibers without the above-mentioned drawbacks. Useful.

Claims (1)

[Claims] 1 ηinh is 3.0 or more and the apparent density is 1.38
g/ ^cm3 or less, and the amine terminal group is 80−10×
(ηinh) milliequivalent/Kg or less, and a polyparaphenylene terephthalamide characterized by having a carboxylic acid terminal group of 80−10×(ηinh) milliequivalent/Kg or less.