JP2006233378A - Fully aromatic polyamide fiber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fiber composed of a fully aromatic polyamide having high mechanical properties and improved process stability and quality in a spinning production process. <P>SOLUTION: The fiber is composed of the fully aromatic polyamide. Boehmite alumina fine particles are contained in the fully aromatic polyamide. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to wholly aromatic polyamides and fibers made thereof, and more particularly to wholly aromatic polyamide fibers containing boehmite alumina fine particles.

  In recent years, there has been a great interest in increasing the added value and performance of polymers. As a means for increasing the added value and improving the performance of polymers, development of composite materials containing fillers in polymers, that is, fillers and polymers, has been actively conducted.

  In other words, for the purpose of improving the mechanical properties and heat resistance of polymers, fibrous and acicular fillers are used as reinforcing fillers, improving tensile strength, elastic modulus, bending strength, thermal dimensional stability, and creep properties. It is known that various physical properties such as improvement of warpage, wear resistance, surface hardness, heat resistance and impact resistance are improved.

  For example, Japanese Patent Laid-Open No. 2003-119622 (Patent Document 1) discloses a polybenzazole fiber containing 5% by weight or more of carbon nanotubes and improving its compressive strength. If carbon nanotubes, which are shaped like fillers, are simply added to the fiber, their dispersion is insufficient, and improvement in mechanical properties is not always obtained.

That is, in order to improve the mechanical strength of these fibers, it is necessary that the filler is sufficiently dispersed in the resin, but as described above, a polymer in which the filler is highly dispersed has not been obtained yet. So it's true.
JP 2003-119622 A

  The present invention has been made against the background of the above prior art, and its object is to provide a fiber comprising a wholly aromatic polyamide having high mechanical properties and improved process stability and quality in the spinning production process. It is in.

  As a result of intensive research to solve the above-mentioned problems, the present inventors have found that when an aromatic polyamide polymer contains boehmite alumina fine particles, a desired aromatic polyamide fiber can be obtained, and the present invention has been achieved. did.

  That is, according to the present invention, there is provided a wholly aromatic polyamide fiber, which is a fiber made of wholly aromatic polyamide, wherein the wholly aromatic polyamide contains boehmite alumina fine particles.

  According to the present invention, there is provided a wholly aromatic polyamide fiber in which dispersibility of boehmite alumina fine particles is greatly improved, and thereby mechanical properties are improved as much as possible.

Hereinafter, embodiments of the present invention will be described in detail.
The wholly aromatic polyamide in the present invention can be obtained from low temperature solution polymerization or interfacial polymerization of dicarboxylic acid dichloride and diamine in a solution. Specific examples of the diamine component used in the present invention include p-phenylenediamine, 2-chloro p-phenylenediamine, 2,5-dichloro p-phenylenediamine, 2,6-dichloro p-phenylenediamine, and m-phenylene. Examples thereof include diamine, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfone, and 3,3'-diaminodiphenyl sulfone. However, it is not limited to these.
Among these, as the diamine component, it is preferable to use p-phenylenediamine, m-phenylenediamine, and 3,4'-diaminodiphenyl ether singly or in combination.

Examples of the dicarboxylic acid chloride component used in the present invention include isophthalic acid chloride, terephthalic acid chloride, 2-chloroterephthalic acid chloride, 2,5-dichloroterephthalic acid chloride, and 2,6-dichloroterephthalic acid chloride. 2,6-naphthalenedicarboxylic acid chloride and the like, but are not limited thereto.
Of these, terephthalic acid dichloride and isophthalic acid dichloride are preferred as the dicarboxylic acid chloride component.

  Therefore, examples of the wholly aromatic polyamide in the present invention include copolyparaphenylene 3,4'-oxydiphenylene terephthalamide, polyparaphenylene terephthalamide, and polymetaphenylene terephthalamide.

  Examples of the solvent for polymerizing wholly aromatic polyamides include organic polar amide solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylcaprolactam, tetrahydrofuran, Examples thereof include water-soluble ether compounds such as dioxane, water-soluble alcohol compounds such as methanol, ethanol and ethylene glycol, water-soluble ketone compounds such as acetone and methyl ethyl ketone, and water-soluble nitrile compounds such as acetonitrile and propionitrile. These solvents can be used as a mixed solvent of two or more, and are not particularly limited. The solvent is preferably dehydrated.

  In this case, in order to increase solubility, an appropriate amount of a generally known inorganic salt may be added before, during or after the polymerization. Examples of such inorganic salts include lithium chloride and calcium chloride.

  The polymer concentration of the wholly aromatic polyamide solution used in the production of the wholly aromatic polyamide of the present invention is preferably 0.5 to 30% by weight, more preferably 1 to 25% by weight. When the polymer concentration is less than 0.5% by weight, there is little entanglement of the polymer and sufficient stretching cannot be performed. On the other hand, if the polymer concentration exceeds 30% by weight, unstable flow tends to occur when discharging from the nozzle, making it difficult to spin stably.

  Moreover, when manufacturing a wholly aromatic polyamide, these diamine components and acid chloride components are preferably 0.90 to 1.10, more preferably 0.95 to 1.0 as the molar ratio of the diamine component to the acid chloride component. 05, preferably used.

  The ends of this wholly aromatic polyamide can also be sealed. In the case of sealing with an end-capping agent, examples of the end-capping agent include phthalic acid chloride and substituted products thereof, and examples of the amine component include aniline and substituted products thereof.

In the reaction of acid chloride and diamine, an aliphatic or aromatic amine or a quaternary ammonium salt may be used in combination in order to capture an acid such as hydrogen chloride to be generated.
After completion of the above reaction, a basic inorganic compound such as sodium hydroxide, potassium hydroxide, calcium hydroxide, calcium oxide or the like is added and neutralized as necessary.
The reaction conditions do not require special restrictions. The reaction between acid chloride and diamine is generally rapid, and the reaction temperature is, for example, -25 ° C to 100 ° C, preferably -10 ° C to 80 ° C.

  The wholly aromatic polyamide thus obtained can be put into a non-solvent such as alcohol or water, precipitated, and taken out as a pulp. This can be dissolved again in another solvent and used for molding, but the solution obtained by the polymerization reaction can be used as it is as a molding solution. The solvent used for re-dissolving is not particularly limited as long as it dissolves the wholly aromatic polyamide, but a solvent used for the polymerization of the wholly aromatic polyamide is preferable.

In the present invention, it is important that boehmite alumina fine particles are contained in the wholly aromatic polyamide.
Here, boehmite alumina is a needle-like nano compound substantially made of alpha alumina monohydride, and the primary particle diameter is desirably 20 nm or less and the aspect ratio is preferably 3 to 100. When the aspect ratio is 3 or less, it is not preferable because it is not sufficiently oriented in the fiber axis direction and does not contribute to strength improvement. On the other hand, when the aspect ratio exceeds 100, it is difficult to uniformly disperse in the fiber, which is not preferable.

  The boehmite alumina fine particles are preferably contained in the range of 1 to 10% by weight based on the total weight of the wholly aromatic polyamide filament. If the content is less than 1% by weight, mechanical properties may not be improved. On the other hand, if the content exceeds 10% by weight, it is difficult to uniformly disperse boehmite alumina in the spinning solution. It may become.

  The wholly aromatic polyamide fiber of the present invention can improve the tensile strength (T) by 10% or more as compared with that not containing boehmite alumina. Moreover, the breaking elongation equivalent to the thing which does not contain boehmite alumina can be maintained.

Furthermore, the wholly aromatic polyamide fiber of the present invention has a toughness factor (TF) that is 10% or more higher than that containing no boehmite alumina, and preferably has a toughness factor of 20% or more. It is possible to obtain polyamide filaments. Here, the toughness factor (TF) is represented by the product of the tensile strength (T) measured in units of grams / denier and the square root of elongation (E) (%). That is, toughness factor (TF) = T × (E) ^1/2 .

Although the reason why the wholly aromatic polyamide fiber of the present invention has high mechanical properties (tensile strength, elongation, and toughness factor) is not certain, boehmite alumina is oriented in the fiber axis direction by stretching and orientation in the spinning process. It is considered that the mechanical properties are improved by the high orientation and the interaction with the polymer through hydrogen bonding.
Such an effect of improving mechanical properties is particularly prominent when a wholly aromatic polyamide is used as the polymer.

  In the present invention, fillers other than boehmite alumina can be used in combination as long as the physical properties of the fiber are not impaired. Examples of the filler used include non-fibrous fillers such as fibrous, plate-like, scale-like, granular, indeterminate shapes, and crushed products. Specific examples include glass fibers, PAN-based and pitch-based carbon fibers. , Stainless steel fiber, metal fiber such as aluminum fiber and brass fiber, organic fiber such as wholly aromatic polyamide fiber, gypsum fiber, ceramic fiber, asbestos fiber, zirconia fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, Potassium titanate whisker, barium titanate whisker, aluminum borate whisker, silicon nitride whisker, mica, talc, kaolin, silica, calcium carbonate, glass beads, glass flake, glass microballoon, clay, molybdenum disulfide, wollastonite, titanium oxide , Zinc oxide, polyphosphoric acid Calcium, graphite, metal powders, metal flakes, metal ribbons, metal oxides, carbon nanotubes, carbon powder, graphite, carbon flake, such flake carbon. Moreover, said filler can also be used in combination of 2 or more types.

  In addition, said filler can also be used by processing the surface with a well-known coupling agent (For example, a silane coupling agent, a titanate coupling agent, etc.) and another surface treating agent.

  The method for producing the wholly aromatic polyamide fiber is not particularly limited, but a spinning solution (dope) comprising a wholly aromatic polyamide, boehmite alumina fine particles and a solvent is prepared, and the obtained dope is discharged from a nozzle, and from a poor solvent. It can be produced by solidifying in a coagulation bath and drying.

As the solvent used for the dope for spinning, the above-mentioned solvent for producing a wholly aromatic polyamide, a solvent capable of dissolving and dispersing the wholly aromatic polyamide and boehmite alumina fine particles can be used, and these solvents are 2 It can also be used as a mixed solvent of more than one species.
The polymer concentration of the dope for spinning, that is, the concentration of wholly aromatic polyamide is 0.05 to 30% by weight, more preferably 1 to 25% by weight.

  A spinning dope comprising a wholly aromatic polyamide, boehmite alumina fine particles and a solvent is prepared by (A) adding boehmite alumina to a solution of wholly aromatic polyamide, (B) solution of wholly aromatic polyamide and boehmite alumina. And (C) a method in which a wholly aromatic polyamide is added to a solution of boehmite alumina and dissolved.

  Further, the dope for spinning in the present invention includes other components within a range not impairing the effects of the present invention, such as antioxidants, heat stabilizers, weathering agents, dyes, antistatic agents, flame retardants, conductive polymers, and others. The polymer can be added.

  Using the spinning dope obtained by the above method, the fiber is formed into a fiber by a wet method, a semi-dry semi-humid method, etc., and after removing the solvent, the fully aromatic polyamide fiber of the present invention is produced by drying. Can do.

  Further, by stretching the obtained fiber molded body, it is considered that the wholly aromatic polyamide as the polymer matrix and the boehmite alumina fine particles used as the filler are highly oriented, and the high physical properties of the wholly aromatic polyamide fiber are expressed. .

As a drawing method, washing drawing in a coagulated yarn state, boiling water drawing, heating drawing in a dry yarn state, or the like can be performed.
Although there is no restriction | limiting in particular about the draw ratio in this case, It is preferable that it is 1.05 times or more, Furthermore, it is preferable that it is 1.1 times or more. When the draw ratio is less than 1.05, the orientation of boehmite alumina in the polymer matrix is not preferable.
Moreover, the elongation and strength of the wholly aromatic polyamide filament can be controlled by controlling the draw ratio.

Hereinafter, the present invention will be described more specifically with reference to examples. In addition, each characteristic in an Example was evaluated in accordance with the following method.
(1) Tensile strength and elastic modulus Measured according to ASTM method D855 using Tensilon universal testing machine RTC-1210A manufactured by Orientec Co., Ltd.
(2) Orientation angle of boehmite alumina fine particles The orientation angle of boehmite alumina fine particles is an arbitrary 2 μm × 2 μm range in the cross section parallel to the fiber axis of the wholly aromatic polyamide fiber containing boehmite alumina fine particles. This is an average value of the inclination of boehmite alumina fine particles with respect to the fiber axis when observed with a microscope (hereinafter abbreviated as TEM) at a measurement number n = 20 at a magnification of 7000 times.

[Example 1]
The raw yarn for mechanical property evaluation was produced by the following procedure. That is, the added boehmite alumina fine particles had an outer diameter of 15 nm and an aspect ratio of 11.
The dispersion of boehmite alumina fine particles was carried out using a bead mill (Nano Grain Mill) manufactured by Asada Tekko Co., Ltd., and the NMP dispersion was adjusted so as to be 6% by weight in N-methyl-2-pyrrolidone (NMP). At this time, 0.3 mm zirconia beads were used as media.

  This boehmite alumina dispersion and NMP were added to an NMP solution containing 6% by weight of copolyparaphenylene 3,4'-oxydiphenylene terephthalamide (para-type wholly aromatic polyamide having a copolymerization molar ratio of 1: 1). The boehmite alumina content in the resulting dope was added at a ratio of 1% by weight based on the total weight of the wholly aromatic polyamide, and the mixture was stirred and mixed at a temperature of 80 ° C. for 4 hours.

  Using the obtained dope, it was discharged from a spinneret with 667 holes, spun into an aqueous solution with an NMP concentration of 30% by weight through an air gap of about 10 mm (semi-dry semi-wet spinning method), washed with water, After drying, and then stretching 10 times at a temperature of 500 ° C., a para-type wholly aromatic polyamide fiber having boehmite alumina fine particles dispersed therein was obtained by winding.

The obtained para-type wholly aromatic polyamide fiber had a total fineness of 1100 dtex, a filament number of 667 filaments, and a single yarn fineness of 1.65 dtex / filament.
Table 1 shows the physical properties of the obtained para-type wholly aromatic polyamide fiber.

[Examples 2 and 3]
In Example 1, the content of the boehmite alumina fine particles to be added is 3% by weight based on the total weight of the para-type wholly aromatic polyamide, or 7% by weight. Para-type wholly aromatic polyamide fibers to which boehmite alumina fine particles were dispersed and added were obtained.
Table 1 shows the physical properties of the obtained para-type wholly aromatic polyamide fiber.

[Example 4]
In Example 1, in place of the boehmite alumina fine particles having an aspect ratio of 11, boehmite alumina fine particles having an aspect ratio of 6 were used in the same manner as in Example 1, except that the para type whole particles to which boehmite alumina fine particles were dispersed and added were used. Aromatic polyamide fibers were obtained.
Table 1 shows the physical properties of the obtained para-type wholly aromatic polyamide fiber.

[Comparative Example 1]
In Example 1, para type wholly aromatic polyamide fiber was obtained in the same manner as Example 1 except that boehmite alumina fine particles were not added.
Table 1 shows the physical properties of the obtained para-type wholly aromatic polyamide fiber.
A raw yarn was prepared, and mechanical properties of the raw yarn were evaluated. The results are shown in Table 1.

  According to the present invention, there is provided a wholly aromatic polyamide fiber in which the dispersibility of boehmite alumina fine particles, which are fillers, is greatly improved, and thereby mechanical properties such as tensile strength and tensile elastic modulus are improved as much as possible. Therefore, it is useful for industrial material applications and functional clothing applications.

Claims (4)

  A fully aromatic polyamide fiber, which is a fiber made of wholly aromatic polyamide, wherein the wholly aromatic polyamide contains boehmite alumina fine particles. The wholly aromatic polyamide fiber according to claim 1, wherein the orientation angle of boehmite alumina fine particles in the wholly aromatic polyamide fiber is 20 ° or less.
(Orientation angle here refers to an arbitrary 2 μm × 2 μm range in a cross section parallel to the fiber axis of wholly aromatic polyamide fiber containing boehmite alumina fine particles, using a transmission electron microscope (hereinafter abbreviated as TEM). The average value of the inclination of boehmite alumina fine particles with respect to the fiber axis when observed at a measurement number n = 20 at a magnification of 7000 times.)   The wholly aromatic polyamide fiber according to claim 1 or 2, wherein the boehmite alumina fine particles have an aspect ratio of 3 to 100.   The wholly aromatic polyamide fiber according to any one of claims 1 to 3, wherein the content of boehmite alumina fine particles is 1 to 10% by weight based on the total weight of the wholly aromatic polyamide fiber.