JPH05209368A - Production of polyphenylene sulfone fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber resistant to heat and chemicals, having high knot strength by oxidizing highly oriented polyphenylene sulfide fibers having specific structure using an organic peracid. CONSTITUTION:Polyphenylene sulfide fibers of >=20Angstrom crystal size and >=60% orientation degree pref. comprising ultrafine fibers is first produced by high- speed spinning at >=4000m/min of a polymer composed of structural unit of formula I. The fibers is then put to oxidation treatment using an organic peracid (pref. peracetic acid) to convert the structural unit to a new structural unit of formula II, thus obtaining the objective polyphenylene sulfone fibers comprising ultrafine fibers of >=20Angstrom crystal size and >=60% orientation degree. The fibers is highly resistant to heat and chemicals such as concentrated sulfuric or nitric acid and also rich in flexibility, and can be suitably used for filters, etc., in sectors being required for heat and chemical resistances.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyphenylene sulfone fiber which is remarkably excellent in heat resistance and chemical resistance, and more particularly to a method for producing an ultrafine fiber or a porous fiber of polyphenylene sulfone. ..

[0002]

As a polysulfone,

[Chemical 3] Microporous fibers using a polymer having a structural unit having an ether bond in the main chain thereof are generally known.

However, so-called polyether sulfone having an ether bond in its main chain generally cannot be melt-spun because it does not have a melting point, is dissolved in an amide-based organic solvent and is made into fibers by a wet spinning method. Was there. Therefore, a large amount of equipment is required for solvent recovery, and the heat resistance and chemical resistance of the obtained fiber have not been remarkably excellent.

Further, polyparaphenylene sulfone polymer is used as polysulfone.

[Chemical 4] Is already known as a powdery form and has a melting point of 500 ° C.
As mentioned above, it is said that the polymer is a crystalline polymer having a remarkable heat resistance. However, with such a high melting point,
Moreover, since there is no solvent capable of dissolving, melt molding and solution molding are practically impossible, and practically useful fibers formed of such a polymer have not been obtained yet.

On the other hand, in recent years, as with polysulfone, polyphenylene sulfide (hereinafter abbreviated as "PPS") is a polymer having a sulfur atom in its main chain, and thermoplastic polymer has excellent heat resistance, electrical insulation, and Since it has chemical resistance and flame retardancy, it is being mainly used as an engineering resin for injection molding materials, and it is being developed as a film or fiber material by taking advantage of its easy molding characteristics.

On the other hand, Japanese Patent Publication No. 60-35370 proposes as a surface hardening method for such a PPS molded article that the fiber surface is treated with hydrogen peroxide or sodium hypochlorite to make it infusible. Has been done. By this treatment, the surface layer of the PPS fiber is oxidized,

[Chemical 5] It is considered that the structural unit represented by was generated. In any case, however, the fibers obtained by such a method are very brittle, and have defects such as cracks and fibrillation of the surface layer (treated portion). Even if the surface layer was not melted, the strength of the surface layer was greatly reduced at a high temperature of 200 to 250 ° C., and it was difficult to use the surface layer at a high temperature. Therefore, its development range is remarkably limited, and yet useful polyphenylene sulfone fibers which are excellent in processability, and highly satisfy both properties of heat resistance and chemical resistance have not been found. Is.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyphenylene sulfone polymer with excellent chemical resistance to a concentrated sulfuric acid and a concentrated nitric acid without impairing the extremely excellent heat resistance originally possessed by the polymer. Rich, flexible,
An object of the present invention is to provide a method for producing a novel polyphenylene sulfone fiber having high knot strength.

[0008]

The present invention has the following configuration.

That is, the following general formula

[Chemical 6] Mainly consisting of structural units shown in and 4000 m
PP produced by spinning at a high speed of not less than 1 / min and having a crystal size of 20 angstroms or more and an orientation degree of 60% or more
S-fibers, with organic peracid, at least 50 mol% of the structural units,

[Chemical 7] With a structural unit of 60% or more and a crystal size of 2
A method for producing a polyphenylene sulfone fiber, which comprises obtaining a polyphenylene sulfone fiber having a thickness of 0 angstrom or more.

[0010]

The present invention will be described in detail below.

The polyphenylene sulfone of the present invention (hereinafter,
"PPSO" is abbreviated as "fiber"

[Chemical 8] Mainly consisting of structural units represented by and occupying in the structural units

[Chemical 9] Is mainly formed from a polyphenylene sulfone chain having a structural unit ratio of 0.5 or more.

[0012]

[Chemical 10] Structural unit ratio (hereinafter, abbreviated as "PPSO conversion rate")
Is less than 0.5, remarkably excellent heat resistance cannot be obtained,
It is preferably 0.7 or more. Especially 0.8
The above is preferable because the heat resistance can be further improved.

The main chain having such a structure may have a so-called three-dimensional structure in which the main chains are partially bonded by oxygen atoms or the like.

Further, the bond between the benzene ring and the sulfur atom in the above structural unit formula represented by the general formula may be either a para bond or a meta bond, but a para bond capable of obtaining high crystallinity is more preferred.

Further, a hydroxyl group, an oxygen atom or the like may be partially added to the benzene ring in the above structural unit formula.

The term "main component" as used in the present invention means containing at least 90 mol% of the above structural units. When the content of the main component is less than 90 mol%, it is difficult to obtain the fiber of the present invention having excellent heat resistance and chemical resistance such as a decrease in crystallinity of the obtained polymer and a decrease in transition temperature. On the other hand, other than 10 mol% other than 90 mol% of the main component may contain an ether bond, a biphenyl bond, a naphthyl bond, a substituted phenyl sulfide bond or the like.

Next, regarding the fine structure of the fiber of the present invention, particularly the degree of orientation, an equatorial line scan 2 by wide-angle X-ray diffraction is used.
It is necessary that the orientation degree is 60% or more as a value calculated from the intensity distribution obtained by scanning the peak observed at Θ = 16 to 17 ° in the circumferential direction.

When the degree of orientation is less than 60%, brittle fibers having a low knot strength tend to be formed, so it is important to have a high degree of orientation. Highly oriented 80% or more, particularly 90% or more is particularly preferable because fibers having high knot strength and excellent heat resistance can be obtained. The size of the microcrystal is 2Θ =
It is important that the crystal size observed at 16 to 17 ° is 20 angstroms or more, and 30 angstroms or more is more preferable.

In this respect, a mere surface hardening method conventionally known as a surface hardness improving method (described above, Japanese Patent Publication No. 60-3537).
No. 0) etc., various structural units are mixed due to side reactions and the like, and because the structure changes only on the surface, the crystallinity of the polymer is destroyed and the crystal size is small.
Further, it was usual that only those having low crystallinity were obtained.

On the other hand, as the crystal size in the fiber axis direction,
The fiber period is preferably in the range of 9.5 to 10.5 angstroms, and more preferably in the range of 9.5 to 10.0 angstroms. The long period of the crystal lamella is preferably 100 angstroms or more.

By exhibiting such a crystal structure, a good polyphenylene sulfone fiber can be obtained.

As the form of the polyphenylene sulfone fiber of the present invention, an ultrafine fiber having a fine fineness or a porous fiber having a large surface area is preferable. For ultrafine fibers,
A single yarn fineness of 0.5 denier or less is desirable. The reason for this is
The smaller the fiber diameter, the higher the strength of the fiber obtained, the less likely it is to fibrillate, and the flexibility (flex resistance).
It is due to the effects of being rich in, and obtaining a dense entangled sheet-like material. On the other hand, the porous fiber preferably has a specific surface area of 0.4 m ² / g or more. The reason for this is that the fibrous material (woven fabric, knitted fabric, non-woven fabric, etc.) using the fiber has a large air layer in the fibrous material because it has a porous fiber morphology, and excellent heat insulation is obtained. Or, since it has a high porosity, it has an excellent liquid retention property against various liquids such as various solvents and electrolytic solutions. Here, the specific surface area means the surface area of the fiber per 1 g of the fiber, so-called BET (Brunaue).
It can be measured by the r-Emmet-Teller method.

Next, the method for producing the PPSO fiber of the present invention will be described below.

The PPSO fiber of the present invention is a highly oriented polyparaphene sulfide having a specific structure (hereinafter referred to as "PP
It is abbreviated as "S") can be obtained by subjecting a fiber to an oxidation treatment with an organic peracid.

First, as a method for producing PPS, it can be obtained, for example, by reacting an alkali sulfide and paradihalogenated benzene in a polar organic solvent at high temperature and high pressure. Particularly, it is preferable to react sodium sulfide and paradichlorobenzene in an amide-based high-boiling polar solvent such as N-methyl-pyrrolidone.

PPS fibers obtained by such a method are then fiberized to obtain PPS fibers. Regarding the method for producing ultrafine PPS fibers, which is a preferred example of the present invention, the melt blow method and the super draw method are used. A method such as removing sea components from the sea-island composite spun fiber or the mixed spun fiber, and an ultrafine method by physical / chemical treatment from the peelable composite spun fiber can also be used in the spinning of the PPS. When spinning is performed using ultrafine fiber-generating fibers such as sea-island composite spun fiber, polystyrene, a copolymer of styrene and acrylic acid and / or methacrylic acid, polyethylene, as a binding component or a dissolution-removing component of the fiber, Any polymer having a fiber-forming ability such as polypropylene, polyester and polyamide can be used without particular limitation. However, since PPS has a high melting point, a high melting point polymer is preferable, and a polymer having a high degree of polymerization is used. Higher polymers are desirable. Particularly in the case of PPS, the polymer has a high melting point (2
Therefore, it is preferable to use a high melting point polymer.

However, the spinning temperature of PPS is 300 to 35.
At high temperatures of 0 ° C, it has been conventionally thought that, when high-viscosity polystyrene is used as a sea component, it cannot be thermally decomposed and used as a sea component. Until now, examples of such ultrafine PPS fiber production have been made. Although it has not been found at all, surprisingly, when the composite spinning with PPS is carried out, the detailed reason is not clear, but stable spinning can be performed without yarn breakage.
It is particularly preferable in terms of easiness of spinning and easiness of releasing melting. It was also surprisingly found that the composite spinning of PPS and polystyrene allows better spinning than the spinning of PPS alone.

In the present invention, the polymer discharged from the spinneret is spun at a high speed of 4000 m / min or more and highly oriented to obtain PPS fibers having an orientation degree of 60% or more.

By the spinning operation as described above, specifically,
Yarn is spun at a high speed of 4000 m / min or more and the crystal size is 20.
A PPS fiber having an orientation of 60 Å or more and an orientation degree of 60% or more is used.

Regarding the fine structure of the PPS fiber, particularly regarding the degree of orientation, it is obtained by scanning the peak observed at the equatorial line scan 2Θ = 19 to 21 ° in the circumferential direction by wide-angle X-ray diffraction. It is important that the degree of orientation is 60% or more as a value calculated from the intensity distribution.

When the degree of orientation is less than 60%, the fibers obtained after the oxidation treatment tend to be brittle fibers with low knot strength, so it is important to have a high degree of orientation. The degree of orientation is more preferably 80% or more, and particularly,
When highly oriented to 90% or more, a fiber having high strength and excellent heat resistance can be obtained, which is particularly preferable.

The size of the microcrystal is 2θ = 19 to 2
It is important that the crystal size observed at 1 ° is 20 Å or more.

On the other hand, the fiber cycle of crystals in the fiber axis direction is preferably 10 to 11 angstroms. The PPS fiber having such a fine structure has high strength and excellent heat resistance and chemical resistance. Then, the polyphenylene sulfone fiber obtained by oxidizing this is a fiber having high strength and high physical properties.

The fine PPS which is a preferred example of the present invention
The fibers are preferably fibers having a denier of 0.5 or less, and the characteristics of such fibers are as follows.

That is, when the polysulfone fiber of the present invention is obtained by using an organic peracid, the reaction interface is wide if the fiber is very fine, and the reaction is easy, and a high PPSO conversion rate can be achieved in a short time. There are great advantages. Also,
Surprisingly, it was found that when the ultrafine PPS fibers were used for PPSO, the degree of orientation of the PPSO ultrafine fibers was extremely high. Therefore, it has been found that the physical properties of the PPSO ultrafine fibers are very high. For example, extra fine PP
In some cases, when the S fiber is made into PPSO, the degree of orientation is improved by 10% or more.

Further, the ultrafine PPS fiber has a high fiber strength, is difficult to be fibrillated, is highly flexible (flexible), and is capable of obtaining a dense entangled sheet-like product, and particularly has resistance to a high pH solution. There are some features.

The fibrous material (woven fabric, knitted fabric, non-woven fabric, etc.) using the fibers has a large air layer retained in the fibrous material and has excellent heat insulating properties, or various solvents, A great effect such as excellent liquid retention can be obtained for various liquids such as an electrolytic solution.

These characteristics are more effective as the fiber becomes thinner, and therefore, the ultrafine P which is a preferred example of the present invention.
The PS fiber is preferably 0.5 denier or less, more preferably 0.3 denier or less, and particularly preferably 0.1 denier or less.
It is 1 denier or less.

On the other hand, regarding the method for producing a porous fiber which is another preferred example of the present invention, the island component is removed from the melt-type sea-island type composite fiber or the mixed spun fiber, or
It can be obtained by removing fine powder from the fine powder mixed spun fiber.

However, in the case of solution-type spinning, PPS is particularly difficult to dissolve at low temperatures, and it is necessary to heat the spinning solution to 200 ° C. or higher. It is desirable because it is easy. When a porous fiber-forming fiber such as the sea-island composite fiber is used, the island component or the dissolution-removing component of the fiber is a fiber-forming ability such as polystyrene, polyethylene, polypropylene, polyethylene terephthalate, or polyamide, as in the case of producing ultrafine fibers. It is not particularly limited as long as it is a polymeric substance having, but in terms of easiness of spinning and easy removal by dissolution, high-viscosity polystyrene, easy-to-dissolve high-polymerization degree copolymerized polyethylene terephthalate, styrene in an alkaline solution. And a higher alcohol ester of acrylic acid and / or methacrylic acid are preferable, and high viscosity polystyrene is particularly preferable.

Next, in the case of the porous fiber-forming fiber, it is made porous by using an appropriate solvent. Of course, when it is used as a filter or a separation membrane, it does not matter even if a fibrous sheet material such as a nonwoven fabric is formed and then treated with a solvent to obtain a sheet material made of porous fibers. Then, the present invention can be achieved by modifying the PPS fiber thus obtained, preferably the ultrafine fiber or the porous fiber, into PPS by the organic peracid described below.

The organic peracid used in the present invention includes performic acid, peracetic acid, perbenzoic acid, perpropionic acid, perbutyric acid,
Examples include m-chloroperbenzoic acetic acid, pertrichloric acid, pertrichloroacetic acid, and perphthalic acid. Among them, peracetic acid is preferable because of its high reaction rate and easy handling.

Such an organic peracid can be obtained by an aldehyde-catalyzed oxidation method (eg, peracetic acid AMP method) or a gas-phase partial oxidation method, or by synthesis from hydrogen peroxide and a carboxylic acid anhydride or chloride. It can be produced by the reaction of diaroyl peroxide and sodium methoxide.

The modification of PPS to PPSO by such an organic peracid is achieved by immersing the PPS fiber in the organic peracid. The treatment conditions in that case differ depending on the fineness or specific surface area of the fiber, the reaction rate of the organic peracid used, etc. and are not particularly limited, but are ultrafine fibers of 0.5 denier or less and 0.4 m ² / g or more. When peracetic acid is used in the porous fiber (1), a high PPSO conversion rate can be achieved even at room temperature. It should be noted that the organic peracid is an explosive chemical, and it is particularly easy to explode at a high temperature. From this point as well, ultrafine fibers or porous fibers which easily attain a high PPSO conversion rate at a low temperature are particularly preferable. ..

[0045]

EXAMPLES The present invention will be described below based on examples, but the present invention is not limited to these examples.

Example 1 Sodium sulfide and paradichlorobenzene were heated at high temperature in N-methyl-2-pyrrolidone in the presence of sodium benzoate.
The PPS pellets having an apparent viscosity of 3700 poise at 300 ° C. obtained by reacting under a high pressure were spun at a spinning temperature of 330.
Spinning was performed at ℃ and a take-up speed of 4500 m / min.

The obtained fiber was a filament yarn of 100 denier / 50 filament. The strength of the obtained PPS fiber was 3.8 g / d. Regarding the crystal characteristics of this PPS fiber, the degree of orientation was 79% according to X-ray diffraction, and 2Θ =
The crystal size at 20.2 ° was 27 Å and the fiber period was 10.5 Å.

Next, this PPS fiber was treated in 20% peracetic acid at 50 ° C. for 5 hours, washed with water and dried.

The fiber thus obtained has a fiber strength of 2.
The breaking elongation was 9 g / d and 18%. 30 this fiber
When the fiber was allowed to stand in a high temperature air of 0 ° C. for 24 hours and the strength and elongation thereof before and after the treatment were measured, no change was observed in the strength and elongation characteristics of the fiber before and after the high temperature treatment.
There was no change in physical properties even after the treatment at 10 ° C. for 10 hours.

The fiber was subjected to solid state high resolution NMR and ESC.
A (Electron Spectroscopy f
or Chemical Analysis), the structural unit of the fiber was

[Chemical 11] Is 87 mol% (structural unit ratio: 0.87),

[Chemical 12] Is 10 mol%,

[Chemical 13] Is 3 mol%, and 2Θ = 1 by wide-angle X-ray diffraction
The degree of orientation at 6.5 ° was 84%, the crystallite size in that direction was 35 Å, and it was confirmed that the crystal structure had a highly oriented crystal structure.

Comparative Examples 1 and 2 Instead of the peracetic acid treatment of Example 1, 9% sodium hypochlorite solution (1 mol H ₂ SO ₄ per 2 mol NaOCl) was used.
At room temperature for 1 day (Comparative Example 1), and 9
When treated at 0 ° C. for 1 hour (Comparative Example 2), the fiber obtained in Comparative Example 1 was found to have a weight increase of 5%. On the other hand, the fibers of Comparative Example 2 became shattered during the treatment, and changed into fibers having no fiber morphology.

When the fiber obtained in Comparative Example 1 was placed on a slide glass and exposed to an alcohol lamp flame from below, it did not melt even when the surface temperature of the slide glass plate reached 500 ° C. It was confirmed that the fibers were infusibilized by the chlorite treatment. However, the fiber of Comparative Example 1 had a fiber strength reduced to about 1 g / d by the hypochlorite treatment, and the elongation at break was also extremely reduced to 2%, and the fiber was changed to a very brittle fiber. ..
Further, when the heat resistance retention rate at 300 ° C. was measured in the same manner as in Example 1, it was as low as 28%.

The fiber of Comparative Example 1 was analyzed by NMR, ESCA,
It is the original structural unit when analyzed by IR

[Chemical 14] Is 61 mol%,

[Chemical 15] Is 6 mol%,

[Chemical 16] Is 8 mol% (structural unit ratio: 0.08),

[Chemical 17]

[Chemical 18] Was produced in a total of 25 mol%, and it was confirmed that the main chain was cleaved in a considerable number.

Example 2 The same PPS pellet as in Example 1 was used as an island component.
Parts, a sea-island type composite spun fiber having 36 island components in one filament at a ratio of 15 parts with high-viscosity polystyrene as a sea component, spinning temperature 320 ° C., take-up speed 470
Spinning was carried out at 0 m / min to obtain a filament yarn of 72 denier / 24 filament. The filament yarn was cut into 10 cm, and polystyrene as a sea component was extracted and removed in trichloroethylene, and then dried.

The obtained ultrafine PPS fiber has a strength of 3.7.
It was g / d and the elongation was 35%. The degree of orientation obtained by X-ray diffraction was 74%, the crystal size at 2Θ = 20.2 ° was 27 Å, and the fiber period was 10.
It was 3 angstroms. Further, even if it was immersed in a 40% aqueous sodium hydroxide solution at room temperature for 10 days, it was an ultrafine PPS fiber having high physical properties without any change in physical properties.

Then, the ultrafine PPS fiber having a single yarn fineness of 0.07 denier was placed in a 9% peracetic acid solution at room temperature (30%).
C.) for 1 hour, washed with water, neutralized, washed with water and dried.

The ultrafine fibers thus obtained have a weight of 26.
% Had increased. The fiber strength was measured to find that it had a strength of 3.0 g / d, an elongation of 24%, and a knot strength of 2.0.
It had a high strength of g / d.

Such a fiber was immersed in concentrated nitric acid having a specific gravity of 1.42 for a day and then taken out, and the strength retention was measured. As a result, it had a high retention of 95% and had excellent chemical resistance. Was confirmed. Regarding the heat resistance, the strength retention ratio before and after exposure to high temperature air of 300 ° C. for 24 hours was 100%, which was extremely excellent.

This fiber was subjected to solid high resolution NMR and ES.
When analyzed by CA, the structural unit of the fiber was

[Chemical 19] Is 92 mol% (structural unit ratio: 0.92),

[Chemical 20] Is 6 mol%,

[Chemical 21] Is 2 mol%, and 2Θ = 16.3 by wide-angle X-ray diffraction.
The degree of orientation at ° was 82%. The crystal size is 3
It was 5 angstroms.

Comparative Example 3 Using the spinneret of Example 1, spinning was carried out at a spinning speed of 2000 m / min under the same conditions as in Example 1 to obtain a filament yarn of 100 denier / 50 filaments.

The degree of orientation of the fibers thus obtained is 40%, and the crystal size at 2Θ = 20.2 ° is 15%.
It was Angstrom. The elongation was 210% and the strength was 1.1 g / d.

When this fiber was treated in the same manner as in Example 1, the structural unit of the fiber was

[Chemical formula 22] Is 90 mol% (structural unit ratio: 0.90),

[Chemical formula 23] Is 6 mol%,

[Chemical formula 24] Was 4 mol%.

However, the elongation of the fiber thus obtained is 3
% Is too low, and the strength is 0.8 g / d,
It could not be used as a practical filament fiber.

[0064]

According to the method of the present invention, it is possible to obtain a polyphenylene sulfone fiber which is markedly excellent in heat resistance and chemical resistance without being deteriorated by concentrated sulfuric acid or concentrated nitric acid.

The polyphenylene sulfone fiber obtained by the method of the present invention, such as a filter for purifying concentrated sulfuric acid, concentrated nitric acid, etc., or desulfurization, various filters in a denitration smoke gas device, a battery separator, a diaphragm, etc., which has been in increasing demand in recent years, It can be preferably used for a filter, a wiper, a sheet-shaped product, and the like in a field in which remarkable heat resistance and chemical resistance are required.

Claims (3)

[Claims] 1. The following general formula: Mainly consisting of structural units shown in and 4000 m
Polyphenylene sulfide fiber having a crystal size of 20 angstroms or more and an orientation degree of 60% or more, which is spun at a high speed of not less than 1 / min, and at least 50 mol% of the structural unit is prepared by using an organic peracid. 2] With a structural unit of 60% or more and a crystal size of 2
A method for producing a polyphenylene sulfone fiber, which comprises obtaining a polyphenylene sulfone fiber having a thickness of 0 angstrom or more. 2. The production of polyphenylene sulfone fiber according to claim 1, wherein ultrafine fibers of 0.5 denier or less are used as the polyphenylene sulfide fiber having a crystal size of 20 angstroms or more and an orientation degree of 60% or more. Method. 3. A porous fiber having a specific surface area of 0.4 m ² / g or more is used as the polyphenylene sulfide fiber having a crystal size of 20 angstroms or more and an orientation degree of 60% or more. 2. The method for producing a polyphenylene sulfone fiber according to 2.