JP2005325287A - Aromatic polyamide dope and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide aromatic polyamide dope exhibiting excellent process passability when molded into fibers or films, and its manufacturing method. <P>SOLUTION: An aromatic diamine is reacted with an aromatic dicarboxylic acid halide in an amide polar solvent, and a by-produced hydrogen halide is neutralized using a neutralizing agent having an impurity content of at most 0.05 wt% to give the aromatic polyamide dope containing not more than 50,000 pieces/g of foreign matter particles having a particle size of at least 0.5 μm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an aromatic polyamide dope excellent in process passability during molding and a method for producing the same. More specifically, the present invention relates to an aromatic polyamide dope excellent in moldability with a controlled number of insoluble coarse particles and a method for producing the same.

  Conventionally, aromatic polyamide (aramid) fibers composed of an aromatic dicarboxylic acid component and an aromatic diamine component, especially para-aramid fibers, are used in industrial applications and clothing by taking advantage of their properties such as high strength, high elastic modulus, and high heat resistance. Widely used in fields such as applications.

  In particular, polyparaphenylene terephthalamide (PPTA), which is a para-based aramid, makes use of its characteristics in industrial materials, protective equipment, and the like, and is the mainstream of aramid. However, when manufacturing PPTA and spinning molding, there are various problems due to the rigidity of the molecule. For example, in the spinning process, the aforementioned polymer cannot be used as a spinning stock solution as it is, but a liquid crystalline spinning stock solution must be prepared with concentrated sulfuric acid and so-called liquid crystal spinning must be performed. The use of concentrated sulfuric acid is disadvantageous both in terms of work environment and in terms of the process from the viewpoint of the corrosiveness of the equipment.

  On the other hand, an attempt to simplify the process by preparing an isotropic spinning stock solution using a general organic polar solvent as a polymerization solvent has been proposed. Specifically, many methods for improving solubility by copolymerizing a component having an ether bond in the molecule have been proposed (for example, Patent Documents 1 to 5). Among these, a wholly aromatic copolymerized polyamide (copolyaramide) obtained by copolymerizing paraphenylenediamine and 3,4'-diaminodiphenyl ether is a polymer having excellent strength and rigidity, and N is a general organic polar solvent. -Methyl-2-pyrrolidone or the like can be used as a polymerization reaction solvent, and the polymer solution after the polymerization reaction can be directly used to form a spinning or the like, thereby greatly improving the process.

  However, in such a process, there is a problem that the filter material life of the filter is shortened due to the presence of impurity foreign particles in the polymer dope and the process passage property is inferior, and it is required to suppress the number of impurity foreign particles. ing.

JP-A-51-76386 JP 51-134743 A JP-A-61-252229 Japanese Patent Laid-Open No. 62-27431 Japanese Patent Laid-Open No. Sho 62-225530

  The present invention has been made against the background of the above-described prior art, and an object thereof is to provide an aromatic polyamide dope excellent in process passability when forming into a fiber or a film and a method for producing the same.

  According to the study by the present inventors, the above-mentioned problem is “an aromatic polyamide solution obtained by reacting an aromatic diamine and an aromatic dicarboxylic acid halide in an amide polar solvent, and present in the solution. It has been found that this can be achieved by "the aromatic polyamide dope having a foreign particle content of 50,000 particles / g or less".

  Another problem is that the above aromatic polyamide solution is produced by reacting an aromatic diamine and an aromatic dicarboxylic acid halide in an amide polar solvent and neutralizing by-product hydrogen halide with a neutralizing agent. In that case, it has been found that the process can be achieved by “a method for producing an aromatic polyamide dope using a neutralizer having an impurity content of 0.05% by weight or less as the neutralizer”.

  Since the aromatic polyamide dope of the present invention has a small number of coarse foreign particles having a particle diameter of 0.5 μm or more, the life of the filter medium normally used for molding becomes long and stable for a long time. Thus, a molded product (yarn, film, etc.) with good quality can be obtained.

  The aromatic polyamide targeted by the present invention is a polymer obtained by reacting an aromatic diamine and an aromatic dicarboxylic acid halide in an amide polar solvent, and the aromatic group has two aromatic rings as oxygen. , And those bonded with a sulfur or alkylene group. In addition, these divalent aromatic groups may include a lower alkyl group such as a methyl group or an ethyl group, a halogen group such as a methoxy group, or a chloro group.

  As aromatic diamines preferably used, paraphenylene diamine, metaphenylene diamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,4'-diaminobiphenyl, 4,4'-diaminobiphenyl, 3 , 4'-diaminodiphenylthioether, 4,4'-diaminodiphenylthioether, 3,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 3,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylmethane 3,4′-diaminodiphenyl ketone, 4,4′-diaminodiphenyl ketone, and the like, and lower alkyl groups such as methyl and ethyl groups, and halogen-substituted derivatives such as methoxy and chloro groups. it can. On the other hand, examples of aromatic dicarboxylic acid halides include terephthalic acid chloride, isophthalic acid chloride, naphthalene dicarboxylic acid chloride, biphenyl dicarboxylic acid chloride, and the like, lower alkyl groups such as methyl and ethyl groups, methoxy groups, and chloro groups. A halogen group substituted derivative can be illustrated.

  Specific examples of aromatic polyamides obtained by reacting such aromatic diamines with aromatic dicarboxylic acid halides include polyparaphenylene terephthalamide, copolyparaphenylene 3,4'-oxydiphenylene terephthalamide, polymetaphenylene isophthalate. Examples include amides. Of these, copolyparaphenylene 3,4'-oxydiphenylene terephthalamide is preferred from the viewpoint of the stability of the resulting dope and the process stability during spinning.

  Examples of the amide polar solvent used in the present invention include N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, dimethylimidazolidinone and the like. N-methyl-2-pyrrolidone (NMP) is preferred from the viewpoints of handleability and stability from polymerization of an aromatic polyamide to dope adjustment and wet spinning process, and toxicity of the solvent.

  The aromatic polyamide dope of the present invention is an aromatic polyamide solution obtained by reacting the aromatic diamine and an aromatic dicarboxylic acid halide in the amide polar solvent, and the particle size present in the solution is 0. The content of foreign particles of 5 μm or less needs to be 50000 / g or less, preferably 10,000 / g or less, particularly preferably 5000 / g or less. When the content of foreign particles exceeding 50,000 μm / g when the particle size exceeds 0.5 μm, when various products are formed using the dope, the filter material clogging of the filter occurs, and the This is not preferable because it is impossible to stably produce a product with good quality.

  The dope concentration of the present invention varies depending on the type and degree of polymerization of the aromatic polyamide, the type of amide solvent, and what kind of product the dope is for molding. Usually, the range of 4 to 10% by weight for para-aromatic polyamide and 15 to 25% by weight for meta-aromatic polyamide is appropriate.

  The aromatic polyamide dope of the present invention described above can be produced, for example, by the following method. That is, an aromatic diamine and an aromatic dicarboxylic acid halide, for example, an aromatic diamine is dissolved in advance in an amide polar solvent, a melt of the aromatic dicarboxylic acid halide is added to the solution, and the mixture is stirred and mixed to react. Let

  The aromatic diamine used here preferably has an impurity content of 0.5% by weight or less, particularly preferably 0.3% by weight or less, and the aromatic dicarboxylic acid halide has an impurity content of 0.5% by weight or less. It is preferable that the amount is not more than wt%, particularly not more than 0.3 wt%. Further, the amide polar solvent preferably has an impurity content of 0.3% by weight or less, particularly 0.1% by weight or less. If these contents exceed the above range, the number of foreign particles in the resulting aromatic polyamide dope tends to increase.

  The polymer solution containing by-produced hydrogen halide after completion of the reaction needs to be neutralized with a neutralizing agent. Examples of the neutralizing agent include calcium hydroxide, lithium hydroxide, water Inorganic alkali fine particles such as magnesium oxide, calcium carbonate, lithium carbonate and calcium oxide are preferably used. The particle size of these fine particles is in the range of 0.5 to 100 μm, preferably in the range of 1.0 to 50 μm. These neutralizing agents may be added as a powder or may be added as a solvent slurry that does not hinder processing, but the addition amount is preferably 50 to 100 mole percent with respect to by-produced hydrogen chloride, More preferably, it is 90-100 mol percent.

  In the present invention, since the neutralizing agent is usually produced from natural minerals, it often contains impurities, and the impurities are mostly mineral fine particles such as silica and alumina, and remain as foreign particles after neutralization. The inventors have determined that the number of foreign particles in the aromatic polyamide dope can be reduced depending on the content of the impurities.

  That is, in the present invention, the content of impurities in the neutralizing agent needs to be 0.05% by weight or less, preferably 0.02% by weight or less. When the impurity content exceeds 0.05% by weight, the number of foreign particles having a particle diameter of 0.5 μm or more in the resulting aromatic dope becomes too large to achieve the object of the present invention.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, each physical-property value in an Example was measured with the following method.
<Amount of impurities in terephthalic acid>
The gas chromatographic analysis was performed by the area percentage method (peak area of terephthalic acid / total peak area × 100).
<Amount of impurities in paraphenylenediamine>
The gas chromatographic analysis was performed by the area percentage method (peak area of paraphenylenediamine / total peak area × 100).
<Amount of impurities in 3,4'-diaminodiphenyl ether>
The gas chromatographic analysis was performed by the area percentage method (peak area of 3,4′-diaminodiphenyl ether / total peak area × 100).
<Amount of impurities in N-methyl-2-pyrrolidone>
The gas chromatographic analysis was performed by an area percentage method (peak area in N-methyl-2-pyrrolidone / total peak area × 100).
<Amount of impurities in calcium hydroxide>
It melt | dissolved in the hydrochloric acid of 1% of density | concentration, it filtered with the Teflon (trademark) membrane filter whose filtration precision is 0.5 micrometer, and measured from the weight of the capture thing of a filter.
<Number of foreign particles in aromatic polyamide solution>
The number of foreign particles in the aromatic polyamide solution was measured with an automatic particle counter, Hiac PC-320, manufactured by Pacific Scientific.
<Life of filter>
The time until the pressure difference before and after the filter reached 2.0 MPa was defined as the lifetime.

[Example 1]
After adding 205 liters of N-methyl-2-pyrrolidone (NMP) to a stirring tank in which nitrogen is flowing inside, 2764 g of paraphenylenediamine (PPD), 5114 g of 3,4'-diaminodiphenyl ether (DAPE) Was weighed in and dissolved. To this diamine solution, 10320 g of terephthalic acid chloride (TPC) was weighed and charged. After completion of the reaction, the reaction solution was neutralized with calcium hydroxide to obtain an aromatic polyamide solution. The amount of foreign matter in each raw material used at this time is summarized in Table 1.

  The obtained aromatic polyamide solution was filtered through a filter having a filtration accuracy of 0.5 μm, and then an aromatic polyamide fiber was obtained by a known solution spinning method. The filter life at this time was as long as 144 hours, and there was no problem.

[Example 2, Comparative Examples 1-2]
An aromatic polyamide solution was obtained in the same manner as in Example 1 except that the amount of impurities in each raw material used the raw materials shown in Table 1. The results are summarized in Table 1.

  Since the aromatic polyamide dope of the present invention has a small number of coarse foreign particles, the life of the filter medium usually used for molding is prolonged, and a molded product (yarn, film, etc.) that is stable for a long time and has good quality. ) Can be obtained.

Claims (6)

  An aromatic polyamide solution obtained by reacting an aromatic diamine and an aromatic dicarboxylic acid halide in an amide polar solvent, the content of foreign particles having a particle diameter of 0.5 μm or more present in the solution being 50,000 Aromatic polyamide dope that is not more than 1 piece / g.   When the aromatic diamine and the aromatic dicarboxylic acid halide are reacted in an amide polar solvent, and the by-produced hydrogen halide is neutralized with a neutralizing agent, the aromatic polyamide solution according to claim 1 is produced. A method for producing an aromatic polyamide dope using a neutralizing agent having an impurity content of 0.05% by weight or less as a neutralizing agent.   The method for producing an aromatic polyamide dope according to claim 2, wherein the neutralizing agent is calcium hydroxide.   The method for producing an aromatic polyamide dope according to claim 2 or 3, wherein the impurity content in the aromatic diamine is 0.5% by weight or less.   The method for producing an aromatic polyamide dope according to claim 2 or 3, wherein an impurity content in the aromatic dicarboxylic acid halide is 0.5% by weight or less.   The method for producing an aromatic polyamide dope according to any one of claims 2 to 5, wherein the content of impurities in the amide polar solvent is 0.3% by weight or less.