JP2008184519A - Method for producing dispersion of wholly aromatic polyamide fine particle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the dispersion of wholly aromatic polyamide fine particles having ≤1 μm mean particle diameter. <P>SOLUTION: This method for producing the dispersion of the wholly aromatic polyamide fine particles is characterized by comprising a first process of polymerizing an aromatic diamine compound with an aromatic acid chloride compound in an aqueous inorganic base solution and an organic water-soluble solvent added with a surfactant selected from an anionic surfactant having a phenyl group and a nonionic surfactant having a phenyl group, and precipitating the wholly aromatic polyamide fine particles to obtain the suspension of the wholly aromatic polyamide coarse particles, and a second process of mechanically crushing the whole aromatic polyamide fine particles in the suspension of the wholly aromatic polyamide fine particles of the first process in the presence of the anionic surfactant having the phenyl group or the nonionic surfactant having the phenyl group. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a wholly aromatic polyamide fine particle dispersion.

  Fully aromatic polyamide (aramid) has excellent heat resistance and mechanical properties, and is widely used for fibers and films, but it is not easy to dissolve or pulverize fully aromatic polyamide, There are restrictions on its use. Accordingly, if a wholly aromatic polyamide fine particle dispersion having an average particle size of 1 μm or less can be produced, its application is expected to expand.

  As a method for synthesizing fully aromatic polyamide fine particles, a first solution containing an aromatic acid chloride compound and a second solution containing an aromatic diamine compound are used in the presence of a solvent soluble in both the first solution and the second solution. A method for obtaining fully aromatic polyamide fine particles by stirring with ultrasonic waves is known (Patent Document 1). However, this method requires a special device such as an ultrasonic generator, and there are various problems in manufacturing to produce fully aromatic polyamide fine particles industrially. Moreover, the manufacturing method of a dispersion liquid is not described. On the other hand, as a method for obtaining non-fully aromatic polyamide fine particles of 1 μm or less, a reprecipitation method in which a non-fully aromatic polyamide is dissolved in an appropriate solvent in the presence of a metal salt and dropped into water has been reported (Patent Document 2). ). However, since it is very difficult to dissolve the wholly aromatic polyamide, the reprecipitation method cannot be used for producing the wholly aromatic polyamide fine particles. In addition, although a method for producing non-fully aromatic polyamide particles of several μm by mechanical pulverization is known, fully aromatic polyamide cannot be mechanically pulverized. From such a situation, development of a simple and simple method for producing a dispersion containing a large amount of finely divided polyamide polyamide particles of 1 μm or less is eagerly desired.

A Shotten-Baumann reaction is known as a reaction for forming an amide from an acid chloride compound and an amine compound in the presence of an aqueous inorganic base solution such as sodium hydroxide (Non-patent Document 1). As one of the methods for producing particles, a dispersion polymerization method is known in which a monomer in which a monomer is soluble and a product polymer is insoluble is selected and polymerization is performed in the presence of a surfactant (non-polymerization method). Patent Document 2). In dispersion polymerization, an organic solvent is usually used as a polymerization solvent because of the above-mentioned restrictions. In dispersion polymerization, the particle / continuous phase is an oil / oil combination, and since the difference in polarity between them is generally not large, the effect of the surfactant on dispersion stabilization is small. For this reason, it is difficult to find a solvent or surfactant suitable for the monomer in the dispersion polymerization. In particular, it is usually considered that it is very difficult to produce fine particles having a particle size controlled to 1 μm or less. Even if fine particles of 1 μm or less are obtained, there is a high possibility that the particles aggregate. However, in dispersion polymerization, a suitable surfactant is used to suppress aggregation between particles in the manufacturing conditions such as solvent and surfactant suitable for the raw material (monomer) for the production of fully aromatic polyamide fine particles and mechanical grinding. If it can be found, there is a possibility that a wholly aromatic polyamide dispersion of 1 m or less can be produced without requiring a special apparatus.
JP 20042731 A JP 9-316206 A N. O. V. Sontag, Chem. Revs. , 52, 272 (1953) "Applied technology of ultrafine polymer" CMC Corporation 2001, pages 34-35

  Accordingly, an object of the present invention is to provide a method for easily and simply producing a wholly aromatic polyamide dispersion having an average particle size of 1 μm or less.

  In order to obtain a fully aromatic polyamide fine particle dispersion, the above-mentioned objective was achieved as a result of extensive research on the combination of solvent, monomer, and surfactant in dispersion polymerization, and selection of surfactant in grinding and dispersion by machine. We finally found out what we can do and finally came to complete the present invention.

  That is, the present invention relates to an aromatic diamine in an aqueous solution of an inorganic base and a water-soluble organic solvent to which a surfactant selected from an anionic surfactant having a phenyl group and a nonionic surfactant having a phenyl group is added. A first step of polymerizing a compound and an aromatic acid chloride compound to precipitate wholly aromatic polyamide fine particles to obtain a wholly aromatic polyamide coarse particle suspension, an anionic surfactant having a phenyl group, or a phenyl group A wholly aromatic polyamide fine particle dispersion comprising a second step of mechanically pulverizing the wholly aromatic polyamide fine particles in the wholly aromatic polyamide fine particle suspension of the first step in the presence of a nonionic surfactant having It is a manufacturing method of a liquid.

  It is not easy to pulverize the wholly aromatic polyamide as it is. Usually, it is difficult to obtain fine particles of 1 μm or less by pulverization, but by dispersion polymerization, a fine particle suspension that is easy to pulverize and disintegrate in advance is manufactured. In mechanical pulverization, a dispersion containing 1 μm or less of fully aromatic polyamide fine particles can be obtained by selecting a surfactant that suppresses reaggregation.

  In the present invention, the fine particles mean particles having an average particle diameter of 1 μm or less. In addition, the average particle diameter of 1 μm or less in the present invention refers to an average particle diameter obtained by measuring a scattering intensity distribution by a dynamic light scattering method and by a cumulant analysis method. Moreover, Shimadzu Corporation laser diffraction type particle size distribution apparatus SALD-2100 shall be used for the measurement of the average particle diameter exceeding 1 micron. Specifically, the arithmetic average of the logarithm of the particle size obtained by analyzing the laser diffraction result by Mie's theory is taken, and the volume average particle size calculated therefrom is taken as the average particle size of the particles.

  In the present invention, dispersion refers to a state where fine particles and a dispersion medium are not separated. The fine particle dispersion means a state in which the wholly aromatic polyamide fine particles are dispersed in the surfactant aqueous solution, and the fine particles and the solvent used in the dispersion are not separated even after standing for 5 hours. When the polymerization solvent and the solvent used for mechanical grinding are different, the wholly aromatic polyamide dispersion of the present invention may contain the polymerization solvent as long as the polymerization solvent is about 10% by weight or less. Separation means a state where the interface between the solvent used in the dispersion and the fine particles can be clearly seen.

  According to the present invention, a wholly aromatic polyamide dispersion can be produced by an industrially excellent method. Such a fully aromatic polyamide fine particle dispersion maintains the original characteristics of a wholly aromatic polyamide resin such as heat resistance and mechanical properties as it is. In addition to electronic parts materials, automotive parts, molding fillers, it can be widely applied to applications such as composite materials.

  The present invention relates to an aromatic diamine compound in an aqueous solution of an inorganic base and a water-soluble organic solvent to which a surfactant selected from an anionic surfactant having a phenyl group and a nonionic surfactant having a phenyl group is added. First step of polymerizing aromatic acid chloride compound to precipitate wholly aromatic polyamide fine particles to obtain a wholly aromatic polyamide coarse particle suspension, anionic surfactant having phenyl group, or nonion having phenyl group Of a wholly aromatic polyamide fine particle dispersion characterized by comprising a second step of mechanically pulverizing wholly aromatic polyamide fine particles in the wholly aromatic polyamide fine particle suspension of the first step in the presence of a surfactant. It is a manufacturing method.

  The aromatic dichloride compound used in the present invention is not particularly limited, but is an acid chloride compound used in polyamide synthesis, such as o-phthalic acid dichloride, m-phthalic acid dichloride, terephthalic acid dichloride, 1,4-naphthalene dicarboxylic acid. Acid dichloride, 1,4-anthracene dicarboxylic acid dichloride, 2,5-biphenyldicarboxylic acid dichloride, 4,4'-biphenyldicarbonyl chloride, 4,4'-bibenzyldicarboxylic acid dichloride, 4,4'-methylene dibenzoate Acid dichloride, 4,4′-oxydibenzoic acid dichloride, 4,4′-sulfonyldibenzoic acid dichloride, p-phenylenediacetic acid dichloride, and the like can be used. In the present invention, m-phthalic acid dichloride and terephthalic acid dichloride are particularly preferable.

  The aromatic diamine compound is not particularly limited, but an aromatic diamine compound used in polyamide synthesis, for example, 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenyl ether (DPE), 4,4 '-Bis (4-aminophenoxy) biphenyl (BAPB), 1,4'-bis (4-aminophenoxy) benzene (TPE-Q), 1,3'-bis (4-aminophenoxy) benzene (TPE-R) ), O-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone, 3,4-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone 3,3′-dimethyl-4,4′-diaminobiphenyl, 2,6′-diamino Toluene, 2,4-diamino chlorobenzene, 3,3'-benzophenone, 3,4-diamino benzophenone, can be used 4,4'-diaminodiphenyl benzophenone.

  In the present invention, 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenyl ether (DPE), p-phenylenediamine, m-phenylenediamine and the like are particularly preferable.

  In the combination of aromatic diamine and aromatic acid chloride, the combination of p-phenylenediamine and terephthalic acid chloride is particularly preferable.

  As described above, the polymerization of the aromatic acid chloride compound and the aromatic diamine compound is performed by precipitating wholly aromatic polyamide fine particles in a water-soluble organic solvent in the presence of a surfactant and an aqueous inorganic base solution.

  In the polymerization of the present invention, polymerization is carried out by adding a water-soluble organic solvent solution of an aromatic acid chloride compound to a water-soluble organic solvent solution of an aromatic diamine compound to which a surfactant and an aqueous inorganic base solution are added. It is preferable to deposit group polyamide fine particles. The order of adding the surfactant and the aqueous inorganic base solution to the water-soluble organic solvent of the aromatic diamine compound is not particularly limited. The addition method may be dropping or continuous injection. An aromatic acid chloride compound is added to the solution thus prepared. The addition method may be dropping or continuous injection.

  In the polymerization, it is preferable to stir the reaction system. For stirring, a stirring bar or a stirring blade may be used, but it is preferable to use a stirring blade.

  The concentration of the aromatic acid chloride compound and the aromatic diamine compound in the water-soluble organic solvent solution of the aromatic diamine compound, the water-soluble organic solvent solution of the aromatic acid chloride compound is the aromatic acid chloride compound or the aromatic diamine compound. However, the aromatic acid chloride compound is 0.1 to 30% by weight, and the aromatic diamine is 0.1 to 30% by weight. Is appropriately selected.

  The concentration of the monomer (total of aromatic diamine compound and aromatic acid chloride compound) to be finally added to the polymerization reaction system can be any concentration as long as the monomer is dissolved in the water-soluble organic solvent. Is suitably selected from the range of 0.1 wt% to 30 wt%. The polymerization temperature can be appropriately selected from −20 ° C. to 40 ° C., but −10 ° C. to 20 ° C. is preferable. The polymerization time can be appropriately selected from 1 hour to 10 hours.

  The mixing ratio of the aromatic acid chloride compound and the aromatic diamine compound is about 0.5: 1 to 1.5 in terms of molar ratio, but preferably 0.9: 0.9 to 1.1. .

  The aqueous organic solvent used in the present invention is usually a solvent or mixed solvent selected from at least one of acetone, methyl ethyl ketone, acetonitrile, 1,4-dioxane, and tetrahydrofuran (hereinafter, both are collectively referred to as “solvent”). The solvent used for the aromatic diamine compound and the solvent used for the aromatic acid chloride compound may be the same or different.

  Although the inorganic base used by this invention is not specifically limited, A normal inorganic base, for example, sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. can be used. The inorganic base is added to the water-soluble organic solvent in the form of an aqueous solution, and the concentration of the aqueous inorganic base solution at that time is not a problem as long as it is a concentration that does not cause precipitation of the monomer when added into the reaction system, preferably 1 regulation to 10 regulations. Although the usage-amount of an inorganic base is not specifically limited, Usually, it is 2-10 equivalent with respect to an aromatic acid chloride compound, Preferably it is 2-5 equivalent. The addition method may be dropping or continuous injection.

  In the present invention, the polymerization is carried out in the presence of a surfactant. In general, anionic surfactants, cationic surfactants, nonionic surfactants (nonionic surfactants), amphoteric surfactants and the like are known as surfactants. In addition, a surfactant selected from anionic surfactants having a phenyl group and nonionic surfactants having a phenyl group is used. One or more of these can be used. Specific examples of the anionic surfactant having a phenyl group include sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, sodium alkyldiphenyletherdisulfonate, and the like. Specific examples of the nonionic surfactant having a phenyl group include polyoxyethylene isooctyl phenyl ether, polyoxyethylene styryl phenyl ether, polyoxyethylene cumyl phenyl ether, and the like. The addition amount of the surfactant can be appropriately selected from 0.5% by weight to 50% by weight based on the total weight of the aromatic acid chloride compound and the aromatic diamine compound in the polymerization, and in particular, 5% by weight to 20% by weight. Is preferred.

  The wholly aromatic polyamide coarse particles produced by the polymerization reaction are precipitated in the polymerization solvent.

In the present invention, as the wholly aromatic polyamide coarse particle suspension used in the second step, the reaction product obtained after the polymerization reaction may be used as it is as the wholly aromatic polyamide coarse particle suspension, or the solvent exchange To obtain a desired solvent system. The solvent exchange can be performed by removing the solvent to be exchanged by a method such as a centrifugal operation or a combination of vacuum distillation and solvent addition, and adding the solvent to be exchanged. It is also possible to arbitrarily adjust the solid content concentration of the suspension by performing a centrifugal separation operation or a combined operation of vacuum distillation and solvent addition. In the present invention, a method for preparing a wholly aromatic polyamide coarse particle suspension for use in the second step by exchanging the solvent from the viewpoint that it can be dispersed in a desired solvent and the dispersibility of the particles is good. Is preferably employed. As the solvent to be exchanged at this time, methyl isobutyl ketone, toluene and water are preferable, and water is particularly preferable.

  The solid content concentration in preparing the wholly aromatic polyamide coarse particle suspension to be pulverized in the second step can be appropriately selected from 0.1 wt% to 50 wt%, but is 1 wt% to 20 wt%. It is preferable.

  The wholly aromatic polyamide fine particle suspension obtained in the first step is subjected to the following second step. In the second step, the wholly aromatic polyamide coarse particles in the wholly aromatic polyamide coarse particle suspension are mechanically pulverized in the presence of a specific surfactant.

  The addition amount of the surfactant used for the mechanical pulverization can be appropriately selected from 0.5% by weight to 50% by weight with respect to the solid content concentration. In the present invention, it is particularly preferably 1% by weight to 20% by weight. There is no particular limitation on the timing of addition of the surfactant to the wholly aromatic polyamide coarse particle suspension, and it may be added during the preparation of the wholly aromatic polyamide coarse particle suspension in the first step. It may be added immediately before serving. Also, when using a wholly aromatic polyamide polymerization reaction system as it is as a wholly aromatic polyamide coarse particle suspension, a surfactant is already present in the polymerization reaction system, so it can be directly used for pulverization. It is.

  The surfactant used in this step is a surfactant selected from an anionic surfactant having a phenyl group and a nonionic surfactant having a phenyl group, and has been described as a surfactant used during polymerization The surfactant used for polymerization and the surfactant used for mechanical pulverization may be the same or different. Preferred surfactants include anionic surfactants such as sodium dodecylbenzenesulfonate, sodium alkylnaphthalene sulfonate, sodium alkyldiphenyl ether disulfonate, and nonionic surfactants such as polyoxyethylene isooctyl phenyl ether, polyoxyethylene. Examples include ethylene styryl phenyl ether and polyoxyethylene cumyl phenyl ether.

In mechanical pulverization with a bead mill or the like in the presence of a surfactant, an average particle diameter of 1 micron is obtained from a wholly aromatic polyamide coarse particle suspension obtained by polymerization or a solvent-substituted wholly aromatic polyamide coarse particle suspension. Examples of the mechanical pulverization apparatus that are subjected to mechanical pulverization until the following are obtained include commercially available mechanical pulverization apparatuses. Ball milling equipment, bead mill equipment, sand mill equipment, wet atomization equipment (for example, manufactured by SUGINO MACHINE) In particular, it is preferable to use a bead mill apparatus.

Even the wholly aromatic dispersion obtained in this way may contain a precipitate depending on the case. In that case, the precipitation part and the dispersion part may be used separately. In order to separate the precipitation portion and the dispersion portion and obtain only the dispersion portion, operations such as decantation, filtration, and centrifugation may be performed.

  The polyamic acid fine particles produced in the present invention usually have an average particle size of 500 nm or less, and in a preferred embodiment, an aromatic polyamide fine particle dispersion having a particle size of 400 nm or less can be produced.

  Hereinafter, the present invention will be described in more detail with reference to examples. Among the average particle diameters in the examples, the particle size of 1 μm or less was determined by measuring the scattering intensity distribution by a dynamic light scattering method using a concentrated particle size analyzer FPAR-1000 manufactured by Otsuka Electronics Co., Ltd. and obtained by a cumulant analysis method. . For the particle size distribution of 1 micron or more, a Shimadzu laser diffraction particle size distribution apparatus SALD-2100 was used. Specifically, the arithmetic average of the logarithm of the particle size obtained by analyzing the laser diffraction result according to Mie's theory was taken, and the volume average particle size calculated therefrom was taken as the average particle size of the particles. The infrared absorption spectrum was measured using a system2000FT-IR manufactured by PERKIN ELMER.

Example 1
5.40 g (50 mmol) of p-phenylenediamine was dissolved in 300 ml of acetone, 1.6 g of polyoxyethylene cumylphenyl ether (Nonal 912A, manufactured by Toho Chemical Co., Ltd.) 1.6 g (10% by weight based on the whole monomer), 5N sodium hydroxide 25 ml (125 mmol) was added and cooled to 2 ° C. While stirring at 620 rpm, 10.15 g (50 mmol) of terephthaloyl chloride was dissolved in 150 ml of acetone and added dropwise to 9.9 ml / ml of the reaction solution, followed by stirring at 2 ° C. for 1 hour. The suspension was centrifuged at 3,400 rpm for 10 minutes, and then the supernatant was removed. Acetone was added to the residue and centrifuged at 3,400 rpm for 10 minutes, and then the supernatant was removed. This operation was repeated once more. Ion exchanged water was added to the residue and centrifuged at 3,400 rpm for 10 minutes, and the supernatant was removed. This operation was repeated once more. To about 14 g of the residue, 280 g of 5% nonal 912A aqueous solution was added to prepare a suspension of about 5% wholly aromatic polyamide coarse particles. As a result of pulverizing the suspension with a bead mill apparatus (manufactured by Kotobuki Kogyo Co., Ltd., “Ultra Apex Mill”, 0.05 mm zirconia beads, mill rotational speed: 4300 rpm) for 20 minutes, a wholly aromatic polyamide fine particle aqueous dispersion is obtained. It was. When the pulverized dispersion was measured with a concentrated particle size analyzer FPAR-1000 manufactured by Otsuka Electronics, the average particle size was 307 nm. It was confirmed from the fact that peaks were observed at 3321, 1642 and 1606 cm ⁻¹ in the IR spectrum to be fully aromatic polyamide. Moreover, even if the obtained dispersion liquid was allowed to stand for 1 month, fine particles and water were not separated.

2 is a SEM photograph of fully aromatic polyamide fine particles after polymerization in Example 1. FIG.

Claims (10)

An aromatic diamine compound and an aromatic acid chloride in an aqueous solution of an inorganic base and a water-soluble organic solvent to which a surfactant selected from an anionic surfactant having a phenyl group and a nonionic surfactant having a phenyl group is added The first step of polymerizing the compound and precipitating wholly aromatic polyamide fine particles to obtain a wholly aromatic polyamide coarse particle suspension, an anionic surfactant having a phenyl group, or a nonionic surfactant having a phenyl group And a second step of mechanically pulverizing the wholly aromatic polyamide fine particles in the suspension of the wholly aromatic polyamide fine particles in the first step. The method for producing a wholly aromatic polyamide fine particle dispersion according to claim 1, wherein the anionic surfactant having a phenyl group contains at least one of sodium dodecylbenzenesulfonate, sodium alkylnaphthalenesulfonate, and sodium alkyldiphenyletherdisulfonate. . The wholly aromatic polyamide fine particle dispersion according to claim 1, wherein the nonionic surfactant having a phenyl group contains at least one of polyoxyethylene isooctyl phenyl ether, polyoxyethylene styryl phenyl ether, and polyoxyethylene cumyl phenyl ether. Liquid manufacturing method. 2. The wholly aromatic polyamide fine particle according to claim 1, wherein the aromatic diamine is any of 4,4′-diaminodiphenylmethane (DDM), 4,4′-diaminodiphenyl ether (DPE), p-phenylenediamine, and m-phenylenediamine. A method for producing a dispersion. The process for producing a wholly aromatic polyamide fine particle dispersion according to claim 1, wherein the aromatic acid chloride is either m-phthalic acid dichloride or terephthalic acid dichloride. The method for producing a wholly aromatic polyamide fine particle dispersion according to any one of claims 1 to 5, wherein the water-soluble organic solvent contains at least one of acetone, methyl ethyl ketone, acetonitrile, 1,4-dioxane, and tetrahydrofuran. In the first step, the reaction system in which the wholly aromatic polyamide fine particles are precipitated is solvent-exchanged to prepare a wholly aromatic polyamide coarse particle suspension for use in the second step. A method for producing a wholly aromatic polyamide fine particle dispersion as described. The fully aromatic polyamide fine particle dispersion according to any one of claims 1 to 7, wherein the mechanical pulverization is pulverization by an apparatus selected from a bead mill apparatus, a ball mill apparatus, a sand mill apparatus, and a wet atomization apparatus. Production method. The method for producing a wholly aromatic polyamide dispersion according to any one of claims 1 to 8, wherein the dispersion medium of the wholly aromatic polyamide fine particle dispersion is water. The method for producing a wholly aromatic polyamide fine particle dispersion according to any one of claims 1 to 9, wherein the average particle size of the wholly aromatic polyamide fine particles is 500 nm or less.

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