JPH02216211A - Production of improved poly-p-phenylene terephthalamide fiber - Google Patents

Abstract

PURPOSE:To obtain the subject fiber having excellent fibrillation resistance in high efficiency by applying an aqueous solution of a nylon3-acrylamide copoly mer to the water-containing coagulated yarn and drying or heat-treating the yarn under specific condition. CONSTITUTION:An optically anisotropic dope (the solvent is concentrated sulfu ric acid having a concentration of 95-101wt.%) having a polymer concentration of >=15wt.% is extruded from a spinneret 1 through a gas into a coagulation bath 2 and the coagulated yarn 4 is washed with water in a washing shower tray 11. During or after the water-washing process, the yarn containing >=50wt.% of water is applied with 0.1-10wt.% (based on the dried weight of fiber) of a nylon3-acrylamide copolymer in the form of an aqueous solution supplied from a shower-type oiling apparatus 12. The yarn is dried and/or heat-treated with a drying apparatus 14 at >=170 deg.C. The constituent unit of the copolymer is expressed by formulas [CH2-CH(R)-CONH]m- and -[[CH2-CR(CONH2)]n-(R is H or <=5C alkyl: m and n are integer of >=1).

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for producing polyparaphenylene terephthalamide (hereinafter sometimes abbreviated as PPTA) fibers having improved properties.

More specifically, the present invention relates to a method for producing PPTA fibers that have excellent adhesive properties and fibril resistance when used as reinforcing fibers for rubber materials.

(Prior Art) Aromatic polyamide fibers are polymeric materials with excellent heat resistance, chemical resistance, etc., as estimated from their molecular structure. Among them, poly-bara phenylene terephthalamide fibers are particularly popular due to their high specific strength and specific modulus.
It is known to be useful as a material for protective clothing, ropes, cords, cables, belts, etc., and as reinforcing fibers for thermoplastic or thermosetting resins and rubber.

However, PPTA fibers are easily fibrillated due to friction between fibers or other materials, which causes fluffing and single thread breakage, making it impossible to bring out the original high strength and high modulus of elasticity. It has the following drawbacks.

Such defects not only cause a decline in mechanical performance, but also cause troubles in the spinning process and processing processes for various uses.

In order to improve this fibrillation, for example,
A method of producing a copolymer by partially introducing aliphatic chains into the main chain of a PPTA-based polymer has been proposed (Japanese Patent Laid-Open No. 60-181317, Japanese Patent Laid-Open No. 61-19814, etc.); Since it is a copolymer containing group chains, there are problems such as a decrease in heat resistance and mechanical properties. In addition, a method of coating the fiber surface with epoxy resin, nylon resin, etc. has been proposed, but as a result of the poor adhesion of such resin to PPTA fibers, it may easily peel off due to friction or other abrasions. No material has been found that can achieve a sufficient improvement effect, such as the fact that the fiber itself splits in the fiber axis direction due to stress (this is also fibrillation).

(Problems to be Solved by the Invention) The present invention has been made in order to solve the above-mentioned drawback, that is, fibrillation that easily occurs due to friction between fibers or other materials, and its purpose is to improve the durability. An object of the present invention is to provide a method for efficiently producing high-performance polybalaraphenylene terephthalamide fibers with excellent fibrillarity.

(Means for Solving the Problems) In order to achieve the above object, the present inventors were studying the behavior of fibers in a water-containing state during the manufacturing process of PPTA-based fibers, and coincidentally found that the fibers The present invention was completed based on the discovery that fibers impregnated with the copolymer described below can be impregnated with a copolymer as described below, and that by drying or heat-treating the impregnated fibers under specific conditions, fibers that are extremely unlikely to fibrillate can be obtained. be.

That is, in the present invention, an optically anisotropic dope prepared by dissolving a poly-balara phenylene terephthalamide-based polymer in agricultural sulfuric acid with a concentration of 95 to 101% by weight to a polymer concentration of at least 15% by weight is prepared by using a spinneret. After extruding into a gas and then into a coagulation bath and pulling out the coagulated thread from the coagulation bath,
In the method for producing poly-balanic phenylene terephthalamide fibers, which involves washing and drying, the following formulas [1] and [2] are applied to yarns that contain at least 50% by weight of water after being drawn out from the coagulation bath and washed with water or after being washed with water. A nylon-3-acrylamide copolymer (hereinafter referred to as NA
An aqueous solution of NA copolymer (abbreviated as copolymer) is applied so that the NA copolymer is 0.1 to 10% by weight based on the amount of dry fiber Ii, and then dried and/or heat treated at a temperature of at least 170°C. This is a method for producing polyvara phenylene terephthalamide fiber, which is characterized by the following.

However, in 2 [1] and [2], R represents hydrogen, an alkyl group having 5 or less carbon atoms, and m and n represent integers of 1 or more.

The poly-bara phenylene terephthalamide polymer used in the present invention is woody and consists of PPTA. Here, the meaning of "essentially" means that polymers other than PPTA [e.g., poly-(m-phenylene terephthalamide), poly-(p- phenylene isophthalamide)
, poly(m-phenylene isophthalamide), poly(polymethylene terephthalamide), aliphatic polyamide, alicyclic polyamide, polyester, polyimide, polyurethane, polyurea, etc.), or PPTA is blended with other repeating units (e.g. , p-phenylene units with nuclear substitution, biphenylene units with nuclear substitution or unsubstituted,
0-phenylene units, m-phenylene units, (poly)methylene units, pyridylene units, bonding units such as esters, urethanes, ureas, ethers, thioethers, etc.) are copolymerized, and various additives and compounding agents (e.g. This means that dyes, antioxidants, ultraviolet absorbers, brighteners, pigments, etc.) may be added.

The PPTA-based polymer used in the method of the present invention should have an intrinsic viscosity (measured in concentrated sulfuric acid at 25°C) of at least 2.0 or more, more preferably 3.0 or more, and still more preferably 3.5 or more. is desirable.

As a solvent for dope preparation used for spinning, 95 to 10
Concentrated sulfuric acid at a concentration of 1% by weight, preferably from 97.5 to 100.5% by weight is used. Specifically, the concentration should be appropriately selected depending on the type of polymer, intrinsic viscosity, and concentration of the polymer dissolved in the dope used for spinning. When the concentration of concentrated sulfuric acid is less than 95%, the solubility of the polymer is poor, and therefore a suitable spinning dope cannot be obtained.
Moreover, the viscosity of the dope increases, which not only makes transportation and filtration difficult, but also makes the mechanical properties of the resulting fibers unsatisfactory. On the other hand, when the concentrated sulfuric acid concentration exceeds 101% by weight, that is, the fuming sulfuric acid containing a large excess of S(h), it is difficult to handle and the polymer hardly dissolves. It is known that fuming sulfuric acid has good polymer solubility and provides a preferable spinning dope.However, when a large excess of 5Off is present in concentrated sulfuric acid, the internal structure of the resulting fibers is affected. This results in voids, a matte appearance, poor mechanical properties, and a slow withdrawal rate from the coagulation bath.

The dope used for spinning must be prepared to contain 15% by weight or more of PPTA polymer in order to obtain high performance fibers. This concentration is specifically determined by the intrinsic viscosity and type of polymer used and the concentration of concentrated sulfuric acid.

The temperature of the spinning dope is preferably any temperature between about 100° C. and the lowest temperature at which the dope exhibits optical anisotropy and has sufficient fluidity to be handleable. Specifically, the temperature of the spinning dope is appropriately determined in consideration of the polymer concentration, type, sulfuric acid concentration of the solvent, spinneret orifice diameter, discharge linear velocity, etc.

The tubes thus prepared must be extruded through a spinneret into a gas and then into a coagulation bath. The dope is degassed, filtered, and weighed before passing through the spinneret.
Particularly preferred for industrial production. The shape of the spinneret, the number of holes, the size of the holes, etc. are not particularly limited. The diameter of the pores usually ranges from 0.01 to 0.5 rm. The linear speed of the dope extruded from the spinneret is also not particularly limited, and may be determined solely based on requirements such as productivity and draft, which will be described later. It is important that the dope stream extruded from the spinneret first passes through a gas. This is because when the fibers are suddenly extruded from the spinneret into the coagulation bath without passing gas, it is difficult to make the draft thicker than 1.5, and the resulting fibers have low density and poor strength and elongation. Gases include air, nitrogen, argon, oxygen, etc. Air is the most preferable from economical advantages and operability. is about 0.2~50cm<
Leprosy is appropriate. The dope stream forced into the gas must then be forced into a coagulation bath where it undergoes coagulation.

Water is preferably used as the coagulating liquid, but monohydric or polyhydric alcohols such as methyl alcohol, ethylene glycol, glycerin, and isopropanol, mixtures of water and the above alcohols, acid aqueous solutions such as sulfuric acid, and hydroxylated Aqueous alkaline solutions such as ammonium and aqueous solutions of various salts such as calcium chloride are used. There are no particular restrictions on the temperature of the dope or coagulation solution during this wet spinning, but
- In general, it is desirable that the temperature is in the range of -10 to 40 °C,
The shape of the coagulation bath is not particularly limited, but from the viewpoint of increasing the spinning speed in industrial production, a so-called funnel-shaped coagulation bath as shown in Fig. 3 of JP-A-55-122012 is preferred. Preferably, a bath is used.

The dope stream extruded into the coagulation bath undergoes coagulation in the coagulation bath and the coagulated thread is then removed from the coagulation bath by at least 3°0.
In order to obtain fibers with high strength and high modulus, it is desirable to draw the fiber at a draft speed of 4.0, more preferably 4.0.
This is the draft.

Here, the draft is the value obtained by dividing the linear velocity of the coagulated filament when it is drawn out from the coagulation bath by the linear velocity of the gutter passing through the spinneret.

The coagulated filament drawn out from the coagulation bath is washed with water. Washing with water is performed in one stage or in two or more stages, and in order to perform this effectively, it may be combined with an alkaline aqueous solution such as caustic soda. It is preferable to extract and remove the solvent as much as possible by washing with water. For example, when sulfuric acid is used as the solvent, it is preferable that the residual amount is about 1% by weight or less. The method of washing with water is not particularly limited. For example, the method of running the water in a water bath, the method of spraying water on a rotating roller, the method of washing with water while wrapped around a bobbin or a rope, or the method of depositing it on a net. The method may be selected from methods such as applying water or a combination of these methods.

In the present invention, the NA copolymer having the structural units represented by formulas [1] and [2] is added to the yarn that has been washed with water and has a water content of 50% by weight or more.

The NA copolymer used in the present invention has CL as a monomer.
= CCONI (The acrylamide derivative represented by z can be easily obtained by anionic polymerization under conditions where so-called hydrogen transfer polymerization occurs.

The molecular weight (Mh) of such NA copolymer is not particularly limited in the present invention, but is usually 1000 to 8
00,000 is used. Further, the ratio of the β-alanine unit represented by the formula [1] and the acrylamide unit represented by the formula [2] may be 10 to 90% by weight, and usually the β-alanine unit represented by the formula [2] is 10 to 90% by weight. An NA copolymer containing 40 to 60% by weight of acrylamide units is used.

Such copolymers are usually water-soluble, and as the ratio of β-alanine units represented by formula [1] increases, the solubility in water decreases.

An aqueous solution of the NA copolymer can be easily prepared by pouring the NA copolymer into water and stirring to dissolve it. or,
In some cases, the aqueous solution may be mixed with acetone,
It is also possible to add it to a general-purpose solvent such as ether or alcohol and stir it, and use it as a dispersion if necessary.

The concentration of the aqueous solution of the NA copolymer may be appropriately selected depending on the processing method, processing speed, water retention rate of the fibers, target adhesion amount, etc., but is generally selected within the range of 0.1 to 20% by weight. Often.

Such an aqueous solution may contain, for example, a dispersant, an antistatic agent, a rubber latex, a thickener, a light stabilizer, an antioxidant, etc., as long as they do not impair the effects of the present invention, such as by sensitively reacting with the NA copolymer. It can also contain various processing agents such as.

The NA copolymer aqueous solution can be applied to the yarn by spraying or showering the yarn, by immersing the yarn in the aqueous solution, or by applying the aqueous solution to the roll surface. Any method may be used, such as a method of forming a film and bringing the thread into contact with the film, and a suitable method may be selected as appropriate depending on the purpose and application rate.

In the method of the present invention, the amount of NA copolymer applied to the yarn is an extremely important factor, and needs to be 0.1 to 10% by weight. If the amount is less than 0.1% by weight, the fibrillarity cannot be sufficiently improved.

On the other hand, if the content is 10% by weight or more, although good results are obtained in terms of fibril resistance, the elongation decreases due to hardening of the fibers, resulting in a decrease in toughness and impact resistance, which is not preferable. In the present invention, a suitable amount of application is 0.2 to 8% by weight, more preferably 0.5 to 6% by weight. Incidentally, the amount applied here refers to the value relative to the weight of the fiber after drying.

The yarn to which the NA copolymer has been applied in this manner is dried as it is, after washing the NA copolymer adhering to or accompanying the surface with water in some cases.

In the present invention, the NA copolymer is applied as described above and then dried.

In order to obtain fibers with improved fibrillation resistance, it is essential that drying be carried out at a temperature of 170'C or higher.

In order to improve fibril resistance, it is necessary to increase the bonding strength in the direction perpendicular to the fiber axis, and for this purpose it is necessary to thermally crosslink the impregnated NA copolymer. NA copolymers undergo thermal crosslinking at temperatures above 170°C.

Therefore, a drying temperature of at least 170'C is required.

In addition, in drying, it is not preferable to use a temperature that is too high because it causes coloration and decomposition of the poly(phenylene terephthalamide) polymer and NA copolymer constituting the fibers, and decomposition and deterioration of the fibers, so it is usually preferable to select a temperature of about 300°C or lower. .

It is also useful to carry out an additional heat treatment following drying. The temperature in this case is also 170℃ to about 300℃ for the above reason.
It is best to choose within the range of . Processing time is usually 10
It is preferably carried out within a range of seconds to 60 minutes.

It has been found that the fibers thus obtained not only have improved fibril resistance, but also have enhanced adhesion to rubber or resin.

The detailed reason for this effect is unknown, but in the method of the present invention, it is believed that it is due to the NA copolymer having an anchoring effect, which is densified after being impregnated with the NA copolymer in an undried swollen state. Presumed.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples. still,
In the examples, % indicates weight % unless otherwise specified. In addition, fibril resistance was measured by the following method.

A fiber sample was subjected to frictional abrasion using the apparatus shown in FIG. 2, and the tenacity after abrasion was divided by the intensity before abrasion to obtain a retention rate (χ). At this time, fiber sample 20 has a fiber sample denier XI/
A lo load 19 was applied and the rotor 17 was rotated for 1 minute at a speed of 250 rpm. The rotor 17 has a length of 30111111 from the center extending in the circumferential direction from the center to the tip.
Eight blades 18 are arranged evenly, and their tips are as shown in FIG. 2(B).

Reference example The following PPTA was obtained by a low temperature solution polymerization method.

In the polymerization apparatus shown in Japanese Patent Publication No. 53-43986, 70 parts of anhydrous calcium 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 were added in powder form all at once. 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 Publication No. 43986, and immediately transferred to a twin-screw closed type Niegoo, and the polymerization reaction product was finely pulverized in the same Niigoo. Next, the finely ground material was transferred to a Henschel mixer, and an equal amount of water was added thereto for further grinding, followed by filtration, washing in warm water several times, and
It was dried in hot air at 10'C.

Example 1 PPTA obtained in Reference Example was dissolved in 99.6% sulfuric acid at 75° C. to a polymer concentration of 19 wt., and defoamed under reduced pressure for about 2 hours. While filtering the dope exhibiting optical anisotropy maintained at 75 to 80°C, 10 pores with a diameter of 0.065
The sample was extruded through a spinneret having a spinneret of 0.05 mm, run in air at about 511 IIl, and then extruded into a 30% by weight aqueous sulfuric acid solution maintained at -5'C. After applying a draft 8 and taking out the coagulated thread from the coagulation bath, it was washed with water on a rotating roller. The washed yarn contained approximately 250% water to polymer. This water-washed thread contains 40 β-alanine units (R in 2 [l] is hydrogen) represented by formula [1].
A random copolymer containing 60 mol% of acrylamide units (R in formula [2] is hydrogen) represented by the formula (2) (intrinsic viscosity = 0.59) and a 10% by weight aqueous solution using an oiling roll. After applying the coating in varying amounts, it was taken off with a Nelson roll, rolled up onto a stainless steel bobbin on a wine goo, and left for 2 hours. Next, the fibers wound on this stainless steel bobbin were immersed in water as a bobbin (about 10 minutes), then taken out of the water and dried as a bobbin in a dryer maintained at a temperature of 300°C for 1 hour. .

Table 1 shows the physical properties and fibril resistance of the obtained fibers. It was proved that the fiber produced by the method of the present invention has extremely excellent fibril resistance.

Comparative Example 1 A fiber was obtained in exactly the same manner as in Example 1 except that the random copolymer of Example 1 was not applied. The physical properties of this fiber are listed in Table 1.

Below is a blank space Example 2 The PPTA obtained in the reference example was dissolved in 99.8% sulfuric acid at 80°C so that the polymer concentration was 19.5% by weight, and after defoaming under reduced pressure for about 2 hours, this product was spun. The dope was optically anisotropic. The dope was extruded through a spinneret with 1,000 pores of 0.06 mmφ, and after passing through a 10 mm air layer, it was introduced into 25% dilute sulfuric acid at 5°C and extruded for 300 m/min.
I pulled it out at a speed of 1 minute.

After washing the yarn using the device shown in FIG. 1, various NA copolymer aqueous solutions (51i mass % aqueous solution) shown in Table 2 were washed using the shower type lubricating device shown at 12 in the figure.
was applied, and then dried in the drying device 12 and then rolled up. The fibril resistance and physical properties of the fibers thus obtained are shown in Table 2. The fibers obtained by the method of the present invention had extremely excellent fibril resistance.

Blank space below (effects of the invention) According to the method of the present invention, the NA copolymer can be efficiently impregnated into the yarn in a water-containing state that has not yet been densified, and then the NA copolymer can be impregnated in the drying process. As a result of being densified, PPT has extremely high resistance to friction and abrasion.
It is possible to efficiently produce A-type fibers, and when the obtained fibers are used for ropes, belts, etc., they can provide products with extremely excellent consumption performance such as abrasion resistance and fatigue resistance.

[Brief explanation of the drawing]

Fig. 1 shows an example of a spinning form suitable for carrying out the method of the present invention, Fig. 2 (^) shows an apparatus for evaluating fibril resistance, and (B) shows a blade installed in the apparatus. It is an enlarged view of the tip of. ■--Spinneret, 2--Spinning bath device, 3--Spinning liquid, 4-Coagulated yarn, 5-Direction change roll, 7-Take-up roll, 8--Shake-off roll, 9-Reversal net device, 10- conveyor net device, 11...- shower tray for water washing, 12- oil composition application device, 13
-・- Yarn pressing device, 14-drying device, 15-oiling device, 16-winding machine, 17-・
...Friction rotor for measuring fibril resistance, 18-blade, I9...load, 20- Sample fiber patent application Asahi Kasei Corporation

Claims (1)

[Claims] A poly-paraphenylene terephthalamide based polymer,
At least 15% by weight of agricultural sulfuric acid with a concentration of 95-101% by weight
Poly-paraphenylene terephthalamide is produced by extruding the optically anisotropic dope dissolved to a polymer concentration of In the method for producing fibers, after pulling them out from the coagulation bath and washing them with water, or after washing them with water, the following formula [1
] and [2] Nylon consisting of the structural units represented by
3-Aqueous solution of acrylamide copolymer (hereinafter abbreviated as NA copolymer) is applied so that the NA copolymer is 0.1 to 10% by weight based on the dry fiber weight, and then heated at at least 170°C. Manufacturing method of polyparaphenylene terephthalamide fiber characterized by drying and/or heat treatment at high temperature ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [1] ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ [2] However, , in formulas [1] and [2], R represents hydrogen, an alkyl group having 5 or less carbon atoms, and m and n represent integers of 1 or more.