JPS63282363A - Production of para-orientation type aramide fiber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing para-oriented aramid fibers having high performance and various functions. More specifically, it relates to a method of impregnating yarn with an impregnating agent in a wet state that has just been coagulated and still contains a sulfuric acid solvent to impart various functions, such as adhesion, flame retardancy, and ease of use. The present invention provides a method for producing high-performance aramid fibers having lubricity, antistatic properties, weather resistance, dyeability, etc.

[Conventional technology]

Conventionally, para-oriented aramid is an organic polymer material with high specific strength, specific modulus of elasticity, and excellent heat resistance, so it has been used for protective work clothing, ropes, cables, cords, and various resin reinforcing materials. It is being considered. In these fields of use, in addition to the above-mentioned performance, it is required to provide additional functions such as adhesiveness and flame retardancy.These properties are usually achieved by mixing additives into the fibers. However, since para-oriented aramid is difficult to melt and is poorly soluble, it must be dissolved using a special solvent such as sulfuric acid before spinning, so unlike general meltable polymers, additives are not required. In the method of imparting various functionalities by adding additives to the spinning dope, the types of additives that can be used are limited due to their stability in sulfuric acid solvents. In addition, from the viewpoint of physical properties, mixing of additives may cause undesirable results such as inhibiting the formation of the microstructure necessary for high performance.On the other hand, after being formed into fibers, high crystallinity and high molecular chain It is very difficult to add these additives by force.

Until now, the method for dyeing aramid fibers was
No. 0-173187, No. 60-215884, No. 61-6147883 and No. 52-378
No. 82 discloses a method of reswelling dried yarn in sulfuric acid or a polar organic solvent and then dyeing the yarn. These methods require high temperatures or long periods of time for dyeing, making it impossible to achieve sufficient dyeing, and resulting in a significant deterioration of mechanical properties. A method is disclosed in which the filament is buckled by crimping and dyed starting from the buckled area, but this method can only be applied to fabrics because only the buckled area can be dyed deeply.

On the other hand, Japanese Unexamined Patent Publication No. 50-12322, No. 49-758
No. 24 and JP-A-53-35020 disclose that the light resistance, flame retardance, etc. of aramid fibers are improved by impregnating undried fibers swollen with water with additives such as ultraviolet absorbers and flame retardants. A method for improving is generally disclosed. However, for loosely oriented aramid fibers, the spinning dope has a low polymer concentration and is wet-spun into a high-temperature coagulation bath, so there are many voids, low density, and extremely low strength.

In other words, the characteristic of high strength, which is the greatest feature of the loosely oriented aramid fibers, is impaired. This is because these techniques are based on the premise of producing porous fibers with many voids and a density of about 1.35 g/- or less, which is easy to impregnate.

Further, JP-A-59-94640 discloses a method in which dried or undried yarn is brought into contact with an aqueous solution of an epoxy compound for a short period of time to coat the yarn with the epoxy compound. This method focuses on coating the surface of the yarn with a curable epoxy compound to improve adhesion to the rubber. It cannot be used to impart functions, because in order to impart these functions, additives must be uniformly diffused and impregnated into the fibers.

[Problem that the invention seeks to solve]

Until now, it has not been possible to improve dyeability and weather resistance, or add functionality such as adhesion and flame retardancy while maintaining the characteristics of loosely oriented aramid fibers, such as high strength and high modulus. The current situation is that this has not been done. Therefore, an object of the present invention is to provide a method for producing high-performance loosely oriented aramid fibers that have high strength, high modulus, and are excellent in adhesive properties, flame retardancy, slipperiness, antistatic properties, etc. It is in.

[Means for solving problems]

In order to solve the problems of the above-mentioned conventional technology, the present inventors
By adopting a molding method in which the dope is once extruded into the air through an orifice and impregnating the fibers with a specific residual acid content, surprisingly, the impregnating agent penetrates into the inside of the fibers in an extremely short period of time. As a result, it is possible to obtain loosely oriented aramid fibers that have excellent dyeing properties, weather resistance, flame retardancy, antistatic properties, slipperiness, etc., even if they are dense fibers with no voids and have high strength and high modulus. I discovered that. Furthermore, it has been found that the impregnating agent that has been diffused and impregnated is not easily eluted to the outside, and can be washed after the impregnation step, and can also be neutralized if necessary. Furthermore, the inventors have discovered that the characteristics of high strength and high elastic modulus, which are the most important characteristics of loosely oriented aramid fibers, are not impaired by changing the process as described above, and the present invention has been achieved.

That is, the present invention provides an intrinsic viscosity (ηinh
) and a sulfuric acid-based solvent, an optically anisotropic dope with a polymer concentration of 13% by weight or more is made, and the dope is once extruded into the air through an orifice, and then solidified to obtain a polymer with a concentration of 5% by weight or more. Obtain a fiber containing an aqueous solution of a sulfuric acid solvent of 50% by weight or more based on the dry fiber, then contact this fiber with a liquid containing an impregnating agent to diffuse the impregnating agent into the fiber, and then wash it, Then 100℃
At least 1.41 g characterized in that it dries at or above
This is a method for producing para-oriented aramid fibers having a density of /cd.

In the present invention, "rose-oriented aramid" refers to a polymer in which one or more divalent aromatic groups are directly bonded via an amide group, and the divalent bonding group of the aromatic group is Comrade is 1.4-phenylene (baraphenylene), 4.4
'-Biphenylene, 1,4-naphthylene, etc., coaxially opposite to the aromatic ring, or 1,5-naphthylene, 2°6-naphthylene, (parallel axially opposite directions). This refers to an aromatic polyamide. Examples of aromatic groups include monocyclic or polycyclic carbocyclic aromatic groups such as those mentioned above, as well as 2,5-pyrylidine, 3,4'-biphenylene ether, and the following. ) may also be a heterocyclic aromatic such as.

These divalent aromatic groups may contain one or more lower alkyl groups such as methyl and ethyl groups, methoxy groups, halogens such as chloro, and the like.

Typical examples of these rose-oriented aramids include polyarabenzamide, polyaraphenylene terephthalamide, poly-4,4'-diaminobenzanilide terephthalamide, and poly-N.

N'-p-phenylene bis(p-benzamide) terephthalamide, polyparaphenylene-2,6-natalic amide, copolyparaphenylene/4.4'-(3,3
'-dimethylbiphenylene)-terephthalamide, copolyparaphenylene/2.5-pyridylene-terephthalamide, copolyparaphenyleneterephthalamide/pyromellitimide, copolyparaphenylene-isocincomelonamide/terephthalamide, and the like.

In the rose-oriented aramid used in the present invention, up to 5 mol% of the aromatic groups constituting the molecule are divalent aromatic groups other than the above-mentioned special aromatic groups, such as metaphenylene groups, 3. Replacement with 3'-biphenylene, etc., divalent aliphatic groups such as ethylene, butylene, etc., and replacement of 5 mol% or less of amide bonds with ester bonds, urea bonds, urethane bonds, etc. are also allowed. .

The method for producing these rose-oriented aramids is not limited in carrying out the present invention (for example, from the corresponding diamine and diacid chloride,
It can be easily produced by a low-temperature solution polymerization method known from Publication No. 399 and the like.

The optically anisotropic dope used in the present invention is prepared by dissolving these para-oriented aramids in a sulfuric acid solvent. The solvent preferably used is concentrated sulfuric acid or fuming sulfuric acid of 95% by weight or more, and other sulfuric acid-based solvents include chlorosulfuric acid, fluorosulfuric acid, and the like.

The optically anisotropic dope used in the present invention is obtained at a polymer concentration higher than a certain level determined by the temperature of the polymer, solvent, and solution. Specifically, the optical anisotropy of each combination is observed. This should be confirmed by Generally, concentrated sulfuric acid shows optical anisotropy at around 10% by weight or more.

Optical anisotropy can be confirmed by placing a thin dope-stretched preparation on a slide glass between crossed nicols of a polarizing microscope, and the dark field of the crossed nicols changes to bright field. It can also be confirmed by the fact that it orients itself under shearing force during melting and reflects light diffusely, producing a metallic or pearl-like luster.

The mechanical properties of the fibers obtained by the production method of the present invention are high-performance fibers that exhibit at least a tensile strength of 20 g/d or more, an elongation of 2% or more, and an initial modulus of 250 g/d or more. It should be. Therefore, the degree of polymerization of the para-oriented aramid polymer used must be higher than a certain value, and at least the intrinsic viscosity must be higher than a certain value.
(vinh) of 3.5 or more, preferably 4.5
Use the above.

In addition, the density of the fiber obtained by the method of the present invention is 1.41
g/cd or more, and this density is a basic requirement for having high mechanical performance as described above. The density is preferably 1.43 g/- or more. Further, the present invention is preferably applicable to fibers having a single filament denier of 0.1 to 5 denier. In aramid fibers, when the denier is thick, the density is generally low and the fibers have many voids, and although such fibers are easily impregnated with an impregnating agent, they are insufficient in terms of mechanical performance. The method of the invention most preferably uses 0
．． Applicable to multifilament with a thickness of 5 to 4 deniers.

Such a para-oriented aramid polymer spinning dope is
Prepared by known methods. In this case, concentrated sulfuric acid is industrially advantageously used as the solvent. The concentration of concentrated sulfuric acid is preferably 95% by weight or more, particularly when dissolving a polymer having a high intrinsic viscosity at a high concentration, 97.5% by weight, more preferably 99% by weight or more.

Generally, the higher the polymer concentration of the spinning dope, the easier it is to obtain high-performance fibers, so it is desirable that the polymer concentration is high. Usually it should be at least 13% by weight or more, preferably 15% by weight or more. If the concentration is too low, at least 1.
High performance fibers with a density of 41 g/J are not obtained. However, if the concentration is too high, for example 22% by weight or more, the viscosity of the dope becomes too high, so it is necessary to set the dope temperature high, which tends to cause difficulties in the spinning operation.

Therefore, it should be chosen not to be too expensive. The polymer concentration of the spinning dope is most preferably 16-20%
in weight.

When preparing and using the dope, in the above polymer concentration range, the dope may solidify near room temperature, so it may be handled at a temperature between room temperature and about 80°C.
However, from the viewpoint of avoiding decomposition of the polymer as much as possible, a temperature as low as possible should be selected as long as it does not solidify.

It is recognized that the spinning dope thus prepared has optical anisotropy within the above polymer concentration and doping temperature ranges. The dope is once extruded into the air through a spinneret and then introduced into a coagulation bath.

Since the coagulating or coagulated yarn in the coagulation bath is hardly stretched, the discharged dope is drawn in the air directly below the nozzle and is stretched. In this stretching, if the stretching rate is low, the physical properties of the fiber, such as strength and initial modulus, cannot be sufficiently increased;
If it is too high, the dope flow will be cut off in between, so the stretching ratio is usually set between 4 and 15 times, preferably between 5 and 12 times. The length in the air during which the dope is stretched, that is, the distance from the surface of the spinning nozzle through which the dope is discharged to the surface of the coagulation bath, is usually set in the range of about 1 to 50 m, preferably 3 to 20 wm. However, it is not limited to this. Specifically, it should be determined in consideration of the dope discharge rate from the spinning nozzle, the above-mentioned draft rate, reducing the chance of filament fusion, etc.

The pore diameter of the spinning nozzle used for discharging the dope is
It should be selected depending on the thickness of the fiber to be manufactured and the above draft rate setting, and is usually 0.05~
A hole in the range of 0.10 m is selected, but is not limited to this, and the number of holes provided in the spinning nozzle is as follows:
It should be determined depending on the structure of the fiber to be produced, and is not particularly limited when carrying out the method of the present invention.

In the present invention, it is important that the spinning nozzle and the coagulation bath are separated in order to obtain fibers with high density (fewer voids) and excellent mechanical properties.

In carrying out the invention, water or an aqueous sulfuric acid solution having a concentration of up to 70% is advantageously used as the coagulating liquid. However, for example, aqueous solutions of salts such as ammonium chloride, calcium chloride, calcium carbonate, sodium chloride, sodium sulfate, etc., or mixtures thereof, aqueous ammonia solutions, aqueous sodium hydroxide solutions, or organic solvents such as methanol, ethanol, ethylene glycol, etc. Alternatively, it may be an aqueous solution of these, and is not particularly limited.

The temperature of the coagulation liquid is generally kept at 15°C or less, more preferably 10°C or less, because the lower the coagulation bath temperature, the smaller the amount of voids generated inside the bath, and the lower the density. This is because as the size increases, mechanical performance such as strength also improves. Note that the lower limit of the coagulation bath temperature is not particularly limited, and is up to the melting point (freezing point) determined by the composition of the coagulation bath.

The coagulated fibers are taken out of the coagulation bath by a suitable device such as a take-up roll, subjected to an impregnation step with an impregnating agent, followed by a washing step, and then dried.

Impregnation with the impregnating agent can be carried out by showering the obtained yarn with the impregnating liquid from an appropriate spray nozzle, or by passing the yarn through a bath containing the impregnating liquid. . This impregnation treatment can be accomplished by performing the above treatment while running the yarn at an appropriate speed between a plurality of rolls or guides.

Although there are no restrictions regarding the equipment, it is preferable that the impregnation treatment is performed in a state where the tension is substantially released from the yarn.

Industrially, the method of releasing the tension from the yarn in the process after the coagulation bath is to stretch the yarn containing an aqueous solvent solution from the coagulation bath onto a net conveyor and process it there under no tension. is convenient. The conveyor processing method will be described below.

When the residual solvent concentration is 5% by weight or more, more preferably 10% by weight or more, the coagulated yarn is taken out from the spinning bath via a suitable device such as a take-up roll, and shaken onto a conveyor by a transfer device. be done.

The transfer device used in the present invention includes a single or a pair of cage rolls, a single or a pair of gear-shaped rolls, etc., which are rotated at a circumferential speed equal to or higher than the thread speed. Alternatively, it may be flushed away with a stream of fluid such as water, or sucked and sent using a fluid stream ejector or air sucker.

In some cases, the threads shaken off by the transfer device may
Although it may be deposited directly on the processing conveyor, it may be first shaken down onto another endless conveyor or roller to form a system, and then placed on the processing conveyor with the top and bottom surfaces of the system reversed. When picking up the yarn from the system again after processing, it is preferable to change the method to avoid inconveniences such as tangles and fuzzing of the yarn, as the yarn is taken out from the bottom of the system when there is no reversal operation. In contrast, such a problem does not occur when the above-described inversion process is performed.

In performing such reversing operations, the reversing conveyor or roller moves or rotates at the same linear speed as the beam processing conveyor, but may be set to a different speed as appropriate depending on the thickness of the system and the material and shape of the reversing conveyor or roller. It is preferable to do so.

The structure of the processing conveyor must be such that the washing water or other processing liquid flows or permeates through the belt, and usually, structures such as net-like, knitted fabric-like, perforated plate-like structures are preferably used. As a special example, it may have a structure in which perforated plates are joined together.

In addition, the material of the processing conveyor needs to be able to withstand the coagulating liquid that adheres to the yarns and the chemicals applied during the processing process, and it is more preferable that it also withstands the heating during the drying process and heat treatment process. It is desirable that there be little dimensional change during use.

For example, a wire mesh or perforated plate made of stainless steel, a knitted fabric made of glass fiber, a glass fiber net coated with a fluororesin, a knitted fabric made of fluororesin fiber, a perforated plate or a perforated sheet made of fluororesin are used.

The moving speed of the processing conveyor is slower than the yarn supply speed, i.e., the take-up speed from the spinning bath. ) should be set to about 1.2 times or more, particularly preferably about 10 times or more; if it is less than that, the yarn transferred on the processing conveyor will be at least partially elongated. This method should be avoided since partial tension is generated in the yarn during the impregnation process, making it impossible to completely perform the treatment in a substantially tension-free state, which is the objective of the present invention.

The original yarn density on the processing conveyor is controlled by the transfer rate and transfer width, and is usually o, on a dry system basis.
oos~0.2g/aJ, particularly preferably o, oos~
The range is selected to be 0.1 g/cd. Further, the transfer rate is selected to be <1.2 times or more as described above, with an upper limit of up to 10,000 times, and particularly preferably between 10 times and 2,000 times. Specifically, the transfer width due to the transfer device is changed by changing the falling distance from the transfer device to the reversing device or processing conveyor, by installing a traversing device (traverser) before or after the transfer device, or by installing a traverser after the transfer device. It can be adjusted by installing a swing-type chute, and it varies depending on the total denier and rigidity of the fiber yarn, but generally it can be set to between a few cranes and a few tens of meters, and in special cases it can be set to around 1 meter. It is possible.

Also, the number of yarns transferred onto one processing conveyor is 1
It is not limited to a book, but a large number of yarns are simultaneously transferred at appropriate intervals, and a large number of yarns are placed at appropriate intervals on a processing conveyor, for example, at intervals of about 1 to 1,011, and the yarn is placed in a strip shape. It is also an industrially preferable embodiment from the viewpoint of productivity to deposit it as a liquid, and simultaneously impregnate it and wash it with water.

In the present invention, the reason why the solvent is deposited on the processing conveyor is the residual state of the solvent when it moves with the conveyor and is transferred onto the net conveyor, that is, the concentration of the residual solvent is 5% by weight or more, more preferably 10% by weight. % is led to the impregnation treatment process and impregnated with an impregnating agent.

When impregnating with an impregnating agent, the concentration of the remaining solvent in the yarn is extremely important. The present inventors discharged from the spinneret, coagulated,
It has been found that it is possible to impregnate the yarn with an impregnating agent by processing it under no tension, even in the yarn that has been swollen with water after the normal process of neutralization and washing after releasing the tension. In the state where the solvent remains, it is possible to impregnate the yarn with the impregnating agent in an extremely short time compared to a yarn swollen with water from which the solvent has been substantially removed. This is very important in carrying out industrial production. In other words, the shorter the time required for processing, the lower the production equipment cost and the higher the productivity.

In the yarn provided for impregnation, the amount as well as the above-mentioned solvent concentration is an important requirement, and the ratio to the dry fiber needs to be at least 50% by weight, preferably 100% by weight.
% by weight or more. If the aqueous solvent solution is extremely small, the fiber will be in a so-called half-dry state, and the rate of diffusion from the solution containing the impregnating agent into the interior of the fiber will be significantly reduced, making it impossible to impregnate a practical amount.

The method of impregnation is carried out by supplying a solution containing an impregnating agent onto the processing conveyor by spraying, showering, etc., or by immersing the entire conveyor in the processing liquid.

Impregnation conditions should be set according to the amount of impregnation required for the fiber, and include the type of polymer used, type of impregnating agent, type of solvent, single yarn denier of the fiber, system medium density, and processing conveyor. It depends on many factors such as the structure of

The temperature of the treatment liquid can be set arbitrarily between room temperature and the boiling point of the solvent used, but a high temperature is preferred in order to increase the rate of diffusion into the fibers. The concentration of the impregnating agent in the treatment liquid is usually 0.1 to 50% by weight.

Water is usually used as the solvent, but preferably an aqueous solution, emulsion, dispersion, or the like containing a water-miscible organic solvent in an amount of 3% by weight or more, more preferably 10% by weight or more. Such organic solvents include:
For example, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, 2-
pyrrolidone, acetonitrile, acetone, methanol,
Ethanol, propatool, ethylene glycol, etc. can be used, and it is preferable to mix these solvents with water at a concentration of 3% by weight or more. In particular, since aprotic polar solvents act as carriers during impregnation, Effective for impregnating denier fibers.

On the other hand, the single filament denier of the undried fibers subjected to impregnation is also an important factor. The larger the single yarn denier, the larger the amount of impregnation. Generally, as the denier increases, the density decreases, but there is a difference in the diffusion rate that cannot be predicted from the slight difference in the density of the fibers after drying, and the amount of impregnation increases. Therefore, the preferred single yarn denier is 0.5 in the dry state.
It is at least 1 denier, particularly preferably at least 1.5 denier. This means that slight differences in the density of wet yarns have a large effect on the diffusion rate of the impregnating agent. Particularly in the production of fibers with a tensile strength of 20 g/d or more, i.e., fibers with a low density (both 1.41 g/c+J or more, most preferably 1.43 g/- or more). The manufacturing method of the present invention, which includes a step of releasing tension at the initial stage of fiber structure formation and impregnating the fiber with a so-called carrier liquid, can be utilized very effectively.

The impregnating agent is not particularly limited as long as it is stable against sulfuric acid-based solvents, and depending on the function to be imparted,
Adhesion improvers, flame retardants, slip agents, antifungal agents, etc. are used. For example, acrylamide and the like are used as adhesion improvers, and various phosphate ester derivatives are used as flame retardants. Furthermore, as the antifungal agent, 10-10'oxybisphenoxyarsine and the like can be used. A water-dispersible silica sol or the like is impregnated as a lubricating agent. It is also possible to impregnate two or more types of impregnating agents at the same time, and any one can be selected depending on the application.

A part of the sulfuric acid solvent remaining in the yarn flows out from the yarn during the impregnation process, but in order to further complete removal, the yarn is then led to a water washing process.

Preferably, the washing water is supplied to the top of the system in the form of a shower from a perforated plate, in the form of a mist from a spray nozzle, or along a large number of brush-like fibers to remove the coagulating liquid contained in the precipitate. It is washed, flows through a processing conveyor and is discharged below the conveyor. Here, the method of supplying the washing water is not limited in implementing the present invention, and is not limited to the above example.

For the purpose of complete coagulation or recovery of the coagulated liquid prior to the washing process, the composition of the coagulating liquid, a mixture of the coagulating liquid and water, a neutralizing agent, or other processing liquid is applied by the same means as the washing process. It may also be possible to supply the material to other sources for treatment.

To enhance the effectiveness of washing, use the
and during or after the water washing step, it is also preferred to treat with any number of squeezing rolls etc., and for the same purpose, by suction from below the processing conveyor, the water washing flowing through the processing conveyor It is also preferred to increase the water flow rate.

The reason is not clear at present, but once the impregnating agent has been diffused into the fiber, it will not easily leak out of the fiber unless it is washed with water very harshly. There is.

When drying these fibers, it is necessary to dry them at at least 120°C or higher. This is because the structure of the fiber becomes dense by drying at high temperature, and the impregnating agent once impregnated is firmly held inside the fiber, so that the elution of the impregnating agent from the fiber can be suppressed. The drying temperature is preferably 150°C to 300°C. This also means that it has excellent washing resistance, and the impregnating effect can be maintained even without using a high molecular weight impregnating agent or bonding it to a polymer.

If necessary, heat treatment can be performed at a higher temperature to increase the mechanical strength. Furthermore, stretching can also be carried out after impregnation, prior to drying, or simultaneously with drying. A particularly high elastic modulus can be obtained by stretching the film by about 1.01 to 1.05 times during drying. It is also possible to obtain high elongation by drying under low tension or no tension.

Furthermore, in the present invention, when dissolving in a sulfuric acid-based solvent and molding, some of the aromatic nuclei in the polymer chain may be sulfonated depending on the conditions. This is because an improvement in the exhausting power of the impregnating agent can be seen as a result as long as the mechanical properties of the obtained fibers are not deteriorated, so it is also a preferable embodiment to actively proceed with sulfonation. It is.

Such sulfonation can be conveniently achieved by keeping the dope at a high temperature of about 90° C. or higher during the period from dissolution of the dope to the start of solidification, for example, by utilizing the heat during dissolution or the heat of stirring.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
These examples do not limit the invention in any way.

In the examples, "%" and "part" unless otherwise specified.
represent weight percent and weight part, respectively. Further, the main various parameters used in the method of the present invention were measured as follows.

Intrinsic viscosity measurement method> Intrinsic viscosity ('I? 1 nh) is determined by dissolving a polymer or fiber in 98.5% by weight concentrated sulfuric acid at a concentration (C) of -0.5 g/d1 at 30°C. Measured by method.

Measuring method of strength and elongation properties of fibers> The strength, elongation and initial modulus of fiber yarns are measured using J.
According to the IS standard, the yarn was twisted 8 times per 10 am prior to measurement, and was tested with a constant speed elongation strength tester at a grip length of 203 and a tensile speed of 50%/min.
The elongation rate curve is drawn and read or calculated from it, and is expressed as the average value of 20 measurements.

<Density of fiber> The density value is a value measured at 30°C by a density gradient tube method using carbon tetrachloride-toluene.

Critical oxygen index The limiting oxygen index (hereinafter referred to as [shi.

0, 1. (abbreviated as J) is Japanese Industrial Standard (J-IS)
Based on No. K7201, the yarn itself was measured as a test piece using a flammability tester (manufactured by Suga Test Instruments, model ON-1). All! The lowest oxygen flow rate at which the test piece can burn continuously for 3 minutes or more or 5al1 or more! 111n
, the nitrogen flow rate at this time is Bj! /win(-11,4-
A>, then L, 0.1. is the value represented by .

Washing fastness> The yarn containing the impregnating agent was washed in an aqueous solution containing 0.1% by weight of liquid detergent (score roll 0) at 60°C for 30 minutes.
Next, the sample was rinsed with 40° C. water for 5 minutes, the water was changed, and the sample was further rinsed with 40° C. water for 10 minutes. This series of operations was repeated 10 times, and then air-dried.

Amount and concentration of residual sulfuric acid in fibers> Take out the fibers on the net, wipe them with a paper towel to remove the amount of sulfuric acid on the surface, and accurately measure the weight Wo of the fibers. Add this to an appropriate amount of water and stir while stirring.
．． Titrated with a 5N aqueous solution of caustic soda and converted into the weight of H, SO, Ws/(Wo-W), and the amount of residual sulfuric acid (relative to dry fiber) was determined as (Wo-W)/W.

Phosphorous content in fibers> Accurately weigh about 50 to 100 grams of fiber impregnated with flame retardant and place it in a platinum basket. This is combusted in an oxygen stream, and the gas produced by the combustion is introduced into a mixed solution of 10 rrl of 0.01N caustic soda and IQml of water and absorbed. Water is added to the above solution that has absorbed the combustion gas, and the volume is adjusted to exactly 50 ml.

This solution was subjected to an ion chromatogram (Dionex Model 10 manufactured by Dionex Corporation) to measure the phosphorus content.

At that time, the separation column used was a column filled with TSK Gel-Anion PW (manufactured by Toyo Soda), and the eluent was 0.001
A 1:1 mixed solution of 5 mol/l sodium bicarbonate aqueous solution and 0.0012 mol/l sodium carbonate aqueous solution was used. Further, the quantification of phosphorus was carried out based on a phosphorus content calibration curve prepared by performing the above operation in advance using a known amount of potassium dihydrogen phosphate.

Example 43 (Method for producing poly-p-phenylene terephthalamide) Poly-p-phenylene terephthalamide (hereinafter abbreviated as rPPTA J) was obtained as follows by a low temperature polymerization method. In the polymerization apparatus shown in Japanese Patent Publication No. 53-43986, 70 parts of anhydrous lithium chloride was dissolved in 1000 parts of N-methylpyrrolidone, and then 48.
6 parts were dissolved. After cooling to 8°C, 91.4 parts of terephthalic acid dichloride was added at once in powder form. After a few minutes, the polymerization reaction product solidified into a cheese-like shape, so the
The polymerization reaction product was discharged from the polymerization apparatus according to the method described in Japanese Patent Application No. 3986, and immediately transferred to a two-screw closed kneader, and the polymerization reaction product was pulverized in the same kneader. Next, the finely ground material was transferred to a Henschel mixer, an approximately equal amount of water was added thereto, further ground, filtered, and washed several times in warm water.
Dry in hot air at ℃. Pale yellow P with ηinh of 5.0
95 parts of PTA were obtained.

Note that PPTA with different ηinh can be easily obtained by changing the ratio of N-methylpyrrolidone and monomers (para-phenylenediamine and terephthalic acid dichloride) and/or the ratio between monomers.

Examples 1 to 7 and Comparative Example 1 PPTA with an intrinsic viscosity (17 inh) of 7.05 was dissolved in 99.7% concentrated sulfuric acid so that the polymer concentration was 18.7% while maintaining the temperature at 80°C. Then, a polymer solution for spinning (hereinafter abbreviated as "dope") was prepared.

It was confirmed by polarizing microscopy observation under crossed Nicols that this polymer solution exhibited optical anisotropy.

This dope was left to stand under vacuum for 2 hours to defoam, and then used for spinning.

The dope is passed through a gear pump and filtered using a candle filter made of eight layers of 300-mesh stainless wire mesh, and then passed through a spinning nozzle with a pore diameter of 0.07 φ and 100 holes into a coagulation bath through 5fi air. It was pushed out. A 10% aqueous sulfuric acid solution cooled to 1.5° C. was used as the coagulating liquid. Next, the yarn introduced into the coagulation bath was changed direction using a direction change roll and then led to a Nelson roll. The yarn taken up by the Nelson roll was then transferred to
Using the device shown in Publication No. 88, the yarn is transferred onto a reversing net by a pair of gear nip rolls (rolls in which gear-shaped rolls are shallowly engaged and the yarn is sent out between them), and then the yarn is reversed onto a processing net conveyor. I picked it up. At this time, the concentration of residual sulfuric acid in the fiber was 7.3% by weight, and the amount thereof was 160% by weight relative to the dry fiber.

In the impregnation process, this yarn was treated with a flame retardant manufactured by Meisei Chemical Industry Co., Ltd. using a 10% aqueous solution of 119AO and a 10% acetone solution of tricresyl phosphate under the conditions shown in Table 1. After washing with water to remove sulfuric acid, it was dried and then wound up with a winder.

Table 1 shows the processing conditions and the performance of the obtained fibers.

Comparative Example 2 A yarn was produced in the same manner as in Example 1 except that a PPTA polymer having an intrinsic viscosity (ηinh) of 3.0 was used.

Comparative Example 3 Impregnation treatment was carried out in the same manner as in Example 1 except that the polymer concentration was changed to 12.0%.

Comparative Example 4 Spinning was carried out in the same manner as in Example 1, and the fibers were washed on a net with water prior to impregnation treatment to obtain fibers with residual sulfuric acid concentration and amount of 2.3% by weight and 150% by weight, respectively. The same operation as in Example 1 was performed to obtain PPTA fibers.

Thin sections of the fibers of Examples 1 to 7 were made using a diamond microtome, and surface analysis of the sections using an X-ray microanalyzer (manufactured by JEOL Ltd.) confirmed that phosphorus was uniformly present inside the fibers. On the other hand, in Comparative Example 4, it was observed only in the surface layer of the fibers.

The following margins are Examples 8 to 10 The yarn spun in Example 1 was mixed with an aqueous solution containing 10% acrylamide or 3% N-methylpyrrolidone in the aqueous solution.
The yarn was impregnated with a 0% solution under the conditions shown in Table 2, washed with water, dried, and then wound using a wine goo.

Comparative Example 5 The yarn obtained in Comparative Example 4 was impregnated with acrylamide under the same conditions as in Example 8.

Comparative Example 6 The yarn spun in Example 1 was washed with water, dried, and wound without being impregnated.

For the fibers of Examples 8 to 10 and Comparative Examples 5 to 6, UD prepreg was made using bisphenol A type epoxy resin (DER383, manufactured by Dow Chemical) with a basis weight of about 150'g/rd and a resin amount of 38% to 42%. 18 plies were made, and the nitrogen pressure was 3.7 kg using the autoclave method.
/aJ at 137° C. for 1.5 hours to create a UD laminate. This laminate was processed using a water jet device (manufactured by Sugitsu Machine) at a water pressure of 2,700 kg/item of 6.4 m/wX25.
,4m・JX2. Cut to QWa-t, ASTM023
According to 44, span distance 1Ofi, test spinid 1
．． Layer shear strength (hereinafter referred to as r) at 3 m/sin
The results of the measurement (referred to as ILssJ) are shown in Table 2, and a significant improvement in ILSS was observed compared to the comparative example.

The following margins [Effects of the invention] The para-oriented aramid fibers obtained by the method of the present invention are
Compared to conventional methods, it provides excellent adhesion, flame retardancy, antistatic properties, and flame retardancy without impairing the physical properties of the yarn, especially in areas where high strength and high elastic modulus are expressed, that is, areas with high density.
It is a fiber that is endowed with slipperiness, etc., and also has excellent fastness in its various functions.

As described above, the para-oriented aramid fibers obtained by the method of the present invention have excellent mechanical properties as well as adhesion, flame retardancy, antistatic properties, and ease of use, which were said to be disadvantages of conventional aramid fibers. It is extremely useful in that it can be used in new fields where its use has been limited until now, as it has properties such as slipperiness, weather resistance, and dyeability.

Specific examples of such uses include fire fighters, filaments, chopped strands, tow, pulp, etc.
Protective clothing worn by flight rooms, racing drivers, riders, miners, etc., cords used in high-performance tires, transmissions, conveyor belts, etc., heat-resistant drybelly for public buildings, airplanes, hospitals, chair upholstery and carpets, children, Examples include heat-resistant clothing for hospital patients, sailboats, ropes, etc.

Claims (1)

[Claims] 1. Polymer concentration 13% by weight from para-oriented aramid with intrinsic viscosity (ηinh) of 3.5 or more and sulfuric acid solvent
The optically anisotropic dope described above is made, and the dope is once extruded into the air through an orifice, and then solidified.
A sulfuric acid-based solvent aqueous solution with a concentration of at least 5% by weight and a dry fiber ratio of 5
Fibers containing 0% by weight or more are obtained, and then the fibers are brought into contact with a liquid containing an impregnating agent to diffuse the impregnating agent into the fibers, then washed, and then dried at 100°C or higher. A method for producing para-oriented aramid fibers having a density of at least 1.41 g/cm^3.