KR100960047B1 - High strength poly (폴리 -phenylene terephthalamide) fiber with improved fatigue resistance and method for producing same - Google Patents

Abstract

The present invention relates to a method for producing a fatigue-resistant poly (p-phenylene terephthalamide) fiber containing a silica compound, containing 95 mol% or more of p-phenylene terephthalamide units, containing a silica compound and intrinsic viscosity Spinning from poly (p-phenyleneterephthalamide) of optically anisotropic undiluted solution in the range of 5.5 to 7.0 into a non-coagulant (e.g. air) and then solidifying in a coagulant (e.g. water) to neutralize, wash, dry, etc. It relates to a method for producing poly (p-phenylene terephthalamide) fibers having a yarn elongation of 4.5% or more and a strength of 20 g / d or more through the process of. The poly (p-phenylene terephthalamide) fiber produced by the above method is excellent in fatigue resistance and is used for optical fiber reinforcement materials and various composite materials. To have.

Poly (p-phenyleneterephthalamide), silica compound, fatigue resistance, rubber reinforcement, composite

Description

High tenacity poly (p-phenyleneterephthalamide) fibers having improved fatigue properties and its manufacturing method

The present invention relates to a poly (p-phenylene terephthalamide) fiber having excellent fatigue resistance and strength made from a poly (p-phenylene terephthalamide) polymer containing a silica compound, wherein the fiber produced by the present invention is an optical fiber It provides excellent fatigue resistance to reinforcement materials, various composite materials and reinforcement materials of rubber products.

Poly (p-phenylene terephthalamide) fibers generally have a high elongation at break of 1.5 to 4.4% and have high strength and high modulus of elasticity. The same use had disadvantages.

Conventional techniques for solving this problem include U.S. Pat.Nos. 4,016,236 and 4,560,743, which carefully treat spun fibers on a mesh belt for washing and drying to ensure that the fibers are not substantially tensioned during the cleaning and drying process. A method for producing aramid fibers by a dropping air gap spinning process is disclosed.

In addition, U.S. Patent No. 4,859,393 discloses increased fatigue resistance by airgap spinning fibers with a coagulation bath of 20 ° C. or higher, washing under a tension of 0.2 to 0.35 g / d and drying the fibers under a lower tension of 0.05 to 0.2 g / d. A process for the production of poly (p-phenyleneterephthalamide) fibers having is disclosed.

EP 118,008 discloses a process for producing poly (p-phenyleneterephthalamide) fibers having increased fatigue resistance by passing the fibers into a chamber in a coagulation bath under reduced pressure.

     These prior arts all adopt a method of increasing the breaking elongation of the fiber by lowering the tension when passing through the coagulation bath, or when washing or drying, but substantially the poly (p-phenylene terephthalamide) fiber developed by these methods. The elongation at break of not more than 5.5% did not provide excellent fatigue resistance.

The present invention has been made to solve the problems of the prior art as described above, by supplying silica to the twin screw extruder quantitatively in the solution polymerization step of the poly (p-phenylene terephthalamide) or wet spinning step radioactive The object is to provide a poly (p-phenylene terephthalamide) fiber that is excellent in excellent fatigue resistance and strength.

The present invention for achieving the above object, (A) poly (p-phenylene terephthal) of an optically anisotropic undiluted solution containing 95 mol% or more of p-phenylene terephthalamide unit, containing a silica compound and intrinsic viscosity in the range of 5.5 to 7.0 Amide) from the non-coagulant (eg, in the air) to form a release yarn; (B) passing the discharged yarn through a coagulating solution (eg in water) to solidify; (C) a process of neutralization, washing, drying, and the like, followed by winding the yarn, thereby (1) intrinsic viscosity of 5.0 to 6.0, (2) strength of 18.0 to 26.0 g / d, and (3) 4.5 To (8) poly (p-phenylene terephthalamide) fibers having physical properties of elongation of from 8.0% and shrinkage of from 0 to 3%.

In addition, the silica compound is preferably fumed silica (Fumed Silica).

In addition, the content of the silica compound is preferably 50 to 1000 ppm.

In addition, the content of the silica compound is more preferably 150 to 500 ppm.

In addition, the silica average particle size is preferably 5 to 1000 nm.

Further, in step (A), it is preferable that the non-coagulant liquid be in the air or inert gas immediately before the solidification step.

In addition, the coagulating solution in step (B) preferably comprises 5 to 15 wt% sulfuric acid.

In addition, this outbreak was treated with two strands of poly (p-phenyleneterephthalamide) fibers up and down and treated with resorcinol-formalin-latex (RFL) to (a) 5.5% or less of E2.25 (2.25 g / Elongation at d) + FS (free shrinkage), and (b) a treatment cord having a physical property of strength of 10.0 g / d or more.

The present invention also provides a rubber product in which the treatment cord is incorporated as a reinforcing material.

Hereinafter, the present invention will be described in more detail.

The poly (p-phenylene terephthalamide) polymer used in the present invention contains at least 95 mol% of at least p-phenylene terephthalamide units, preferably is composed of only p-phenylene terephthalamide units and comprises silica compounds.

The poly (p-phenylene terephthalamide) polymer according to the present invention preferably has a ratio of p-phenylenediamine and terephthaloyl chloride raw material to 10.0 to 13.0 wt% based on the sum of all the raw materials and the solvent system. , Solution-condensation polymerization in an N-methyl pyrrolidone (NMP) solution at a temperature of 10 ° C. or less at an equivalent ratio of 0.95 to 1.01, and neutralized, washed with water and dried to obtain pure poly (p-phenylene terephthalamide ) To obtain a polymer. The poly (p-phenylene terephthalamide) polymer thus obtained has an intrinsic viscosity in the range of 5.5 to 7.0.

In the solution polycondensation reaction, it is preferable to add a silica compound of 50 to 1000 ppm. If the amount is less than 50 ppm, the amount of silica compound is too small to improve the radioactivity, and if it is more than 1000 ppm, more than the required silica compound acts as a foreign matter, rather it is a problem during spinning.

In the present invention, the silica average particle size is preferably 5 to 1000 nm. When the silica particle size is less than 5 nm, the cost increases and economics are lowered. If it exceeds 1000 nm, the radioactivity is poor.

The poly (p-phenylene terephthalamide) polymer thus prepared is fiberized according to the following method.

In step (A) corresponding to the spinning step of the present invention, the poly (p-phenylene terephthalamide) dope of the optically anisotropic undiluted solution having an intrinsic viscosity in the range of 5.5 to 7.0 is cooled at a temperature of 70 to 85 ° C. through a pack and a nozzle. By violating wet spinning, a decrease in the viscosity of the polymer due to thermal decomposition and hydrolysis can be prevented.

In the present invention, a static mixer or the like may be installed in the upper part of the pack in order to mix the spun polymer evenly and to increase the uniformity of the dope viscosity for each part of the polymer.

In step (B) corresponding to the solidification cooling step of the present invention, the distance from the start point of the solidification zone to the starting point of the solidification zone, i.e., the air layer, should be formed before the discharge sand generated in the step (A) passes through the solidification zone to solidify. . This zone is called an air gap and can have a length of 3 to 15 mm and a temperature of 10 to 40 ° C. In the coagulation zone, the coagulation solution may have a temperature of 3 to 15 ° C. as water containing sulfuric acid.

The coagulating solution is preferably water containing 3 to 15wt% sulfuric acid. If the sulfuric acid is less than 3wt%, sulfuric acid on the fiber surface quickly escapes to solidify rapidly, but sulfuric acid inside the fiber is difficult to escape easily, forming a skin-core structure of the fiber structure, which significantly reduces the strength of the yarn. If it exceeds the%, the fiber solidification is slowed down, resulting in fusion between fibers and cutting, which makes the spinning work difficult.

In step (C), the solidified yarn is wound around the feed roller for a predetermined number of times, and then washed with water and neutralized to evaporate the moisture from the drying roller.

The poly (p-phenyleneterephthalamide) fibers produced according to the method of the present invention have (1) intrinsic viscosity of 5.0 to 6.0, (2) strength of 18.0 to 26.0 g / d, and (3) elongation of 4.5 to 8.0%. , (4) has a shrinkage of 0 to 3%.

Further, according to the present invention, the drawn yarn can be converted into a treatment code by a conventional treatment method. For example, two cords of 1,500 denier stretched yarns were plyed and cabling at 450 turns / m (twist of standard poly (p-phenylene terephthalamide) treated cord) to prepare cord yarns. Is first deposited in an adhesive liquid (e.g. isocyanate + epoxy resin, or PCP (parachlorophenol) resin + RFL (resorcinol-formalin-latex)) in a dipping tank and then drying zone ) And dried for 150 to 200 seconds at a temperature of 0.0 ~ 3.0% at 110 to 180 ° C, and heat-setting for 45 to 80 seconds at a temperature of 2.0 to 6.0% at 225 to 255 ° C in a hot stretching zone. After dipping in an adhesive liquid (e.g. RFL), drying at 130-170 ° C for 90-120 seconds and heat setting at 225-255 ° C under -2.0-2.0% stretching for 45-80 seconds, E2.25 (less than 2.5%) Treatment cords having elongation at 2.25 g / d) + FS (free shrinkage) and strength of at least 12.0 g / d can be produced.

As described above, according to the present invention, silica is quantitatively added to a twin screw extruder in a poly (p-phenylene terephthalamide) solution polymerization step or a wet-wetting spinning step, so that it has excellent radiation resistance and high strength ( It has been found that p-phenyleneterephthalamide) fibers can be produced and the present invention has been completed. In particular, the treatment cord formed from the high-strength poly (p-phenyleneterephthalamide) fibers of the present invention is excellent in dimensional stability and strength and can be usefully used as a reinforcement material for rubber products such as tires and belts or for other industrial uses.

Hereinafter, the present invention will be described in more detail based on the following examples. However, the following examples are not intended to limit the present invention, but are not limited thereto. Various physical property evaluations of the companies manufactured in Examples and Comparative Examples of the present invention were performed by the following method.

(1) Intrinsic viscosity (I.V.)

Dissolve 0.5g of sample in 95% purified sulfuric acid reagent at room temperature (25 ℃) for 15 hours to concentration 0.5g / 100ml, transfer to Ubbelohde viscometer, hold for 10 minutes in 30 ℃ thermostat, viscometer and suction device (aspirator) was used to determine the number of drops of solution. The falling seconds of the solvent was also determined in the same manner, and then the R.V. and I.V. values were calculated by the following equations (1) and (2).

--------------(1)

--------------(One)

---------------(2)

---------------(2)

Where C represents the concentration of the sample in solution (g / 100ml).

(2) strength

Using Instron 5565 (manufactured by Instron, USA), 250 mm sample length, 300 mm / min tensile speed and 80 turns / s under standard conditions (20 ° C., 65% relative humidity) according to ASTM D 885 Elongation was measured under conditions of m.

(3) density

The density (ρ) of the sample was calculated | required using the xylene / carbon tetrachloride density gradient tube at the temperature of 23 degreeC. At this time, the density gradient pipe has a density in the range of 1.40 ~ 1.48 g / cm ² and was prepared according to the ASTM D 1505.

(4) shrinkage

The sample was left at 20 ° C. and 65% relative humidity for at least 24 hours, and then weighed at a weight of 0.1 g / d to measure the length (L 0), and under a no-tension condition for 30 minutes at 150 ° C. using a dry oven. After the treatment was taken out and left for 4 hours or more, the load was measured, the length (L) was measured, and the shrinkage ratio was calculated by the following Equation 3.

--------------(3)

-------------- (3)

(5) Intermediate Shinto

On the S-S curve, the yarn was elongated at 4.5 g / d and the treated cord was elongated at 2.25 g / d.

(6) Dimensional stability

The dimensional stability (%) of the treatment cord is defined as the high modulus at a given shrinkage as properties related to tire sidewall indentation (SWI) and handling, and E2.25 (elongation at 2.25 g / d) + FS (Free Shrinkage Rate) is useful as a measure of dimensional stability for treatment codes that have undergone different heat treatments, and the lower the better the dimensional stability.

(7) decomposition temperature

2 mg of finely chopped powder in a pan was sealed in a pan, and the temperature at which the weight of the sample was decreased was increased to 10 ° C. per minute from room temperature to 600 ° C. under nitrogen using a PerkinElmer TGA as the decomposition temperature. .

(8) the number of cuttings

The number of rounds is a value calculated according to Equation 4 below.

Number of rounds ÷ (day, pos) --------------- (4)

Example 1

A poly (p-phenylene terephthalamide) polymer of intrinsic viscosity (IV) 6.3 was dissolved in a twin screw extruder in a solid content of 19.5% in 100.1% concentrated sulfuric acid, while side-feeding fumed silica to 300ppm content. The wet wet spinning was carried out at a discharge amount of 430 g / min at a temperature of 72 ° C. At this time, a static mixer having five units was installed in the spinning dope conduit to uniformly mix the dope discharged. Subsequently, the discharged yarn was solidified in a solidifying solution (water) at 3 ° C. having a sulfuric acid concentration of 8 wt% through an air gap of 6 mm in length directly under the nozzle, and then fed through a supply roller, water washing, neutralization, and drying roller to obtain 1500 denier yarn. Wound up.

Thus, the drawn yarn was plyed and cabling two twisted strands of 1500 denier drawn yarn at 450 turns / m (twisted by standard poly (p-phenylene terephthalamide) treatment cord) to prepare cord yarn. The cord yarn was first deposited in a dipping tank in an adhesive solution (e.g. isocyanate + epoxy resin, or PCP (parachlorophenol) resin + RFL (resorcinol-formalin-latex)) and then dried area ( drying in a drying zone for 200 seconds at 0.5% elongation at 170 ° C. and heat setting at 70 ° C. under 0.5% elongation at 250 ° C. in a hot stretching zone, and then again submerged in an adhesive solution (eg RFL). Next, the mixture was dried at 170 ° C. for 120 seconds and heat-set at 250 ° C. under −1.0% of elongation for 80 seconds.

The physical properties of the drawn yarn and the treatment cord thus prepared are shown in Table 1 below.

Examples 2 and 3 and Comparative Examples 1 to 5

An aramid yarn was prepared by performing experiments in the same manner as in Example 1 while changing the silica particle size and silica content ratio as shown in Table 1 below.

The physical properties of the aramid yarn prepared as described above are shown in Table 1 below.

TABLE 1

As shown in Table 1, in the case of Comparative Examples 1 and 2 to which the silica content of more than or less than the appropriate content was added, excellent elongation and stable workability were not obtained under the conditions in which the excellent physical properties as in Example were expressed.

As described above, the present invention not only has excellent spinning workability when squeezing spinning by adding silica in the solution polymerization step or the wet spinning step, and therefore, the poly (p-phenylene terephthalamide) fiber has high It has improved physical properties including strength and high elongation, and the treatment cord formed from the yarn is excellent in fatigue resistance and can be usefully used as a reinforcement for rubber products such as tires and belts or for other industrial uses. The poly (p-phenyleneterephthalamide) fibers produced according to the process of the invention are suitable for various applications requiring high tensile strength, resistance to tensile deformation and high heat resistance, but in particular due to their excellent workability or weaving properties during spinning. Record very few trims even after prolonged radiation.

Claims (7)

(A) from poly (p-phenyleneterephthalamide) of an optically anisotropic stock solution containing at least 95 mol% of p-phenylene terephthalamide units, containing from 50 to 1000 ppm of silica compound, and having an intrinsic viscosity in the range of 5.5 to 7.0; Spinning in the non-coagulant solution and then generating a release yarn; (B) passing the discharged yarn through the coagulating solution to solidify; (C) A poly (p-phenylene terephthalamide) fiber produced by the step of winding a yarn after undergoing a process such as neutralization, washing and drying and having the following physical properties. (1) intrinsic viscosity of 5.0 to 6.0, (2) an intensity of 18.0 to 26.0 g / d, (3) elongation of 4.5 to 8.0%, (4) 0 to 3% shrinkage The poly (p-phenylene terephthalamide) fiber according to claim 1, wherein the silica compound is fumed silica. 3. The poly (p-phenylene terephthalamide) fiber according to claim 1 or 2, wherein the silica average particle size is 5 to 1000 nm. The poly (p-phenylene terephthalamide) fiber according to claim 1, wherein the non-coagulant liquid is in the air or inert gas immediately before the solidification step in step (A). The poly (p-phenylene terephthalamide) fiber of claim 1, wherein the coagulating solution in step (B) comprises 5 to 15 wt% sulfuric acid. A treatment cord having the following physical properties, obtained by treating two strands of the poly (p-phenylene terephthalamide) fibers of claim 1 or 2 up and down and treating with resorcinol-formalin-latex (RFL). (a) E2.25 (elongation at 2.25 g / d) + FS (free shrinkage) of 2.5% or less, and (b) an intensity of 12.0 g / d or more. A rubber product in which the treatment cord of claim 6 is incorporated as a reinforcing material.