JPH086258B2 - Surface-modified wholly aromatic polyamide fiber - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a wholly aromatic polyamide fiber having improved surface strength. More specifically, the present invention provides a wholly aromatic polyamide fiber having excellent wear resistance and excellent twist strength retention in applications such as cords and ropes in which fiber bundles are twisted together.

<Prior Art> Recently, wholly aromatic polyamide fibers are among organic fibers, and in particular, they have new applications in various fields by taking advantage of excellent properties such as high strength, high modulus, high heat resistance, and high chemical resistance. Has been put into practical use.

However, such fibers have high molecular orientation and high crystallinity, so the mechanical properties in the fiber axis direction exhibit an outstanding function, but on the other hand, they are surprisingly brittle in the direction perpendicular to the fiber axis. The fact is also clear.

In particular, fibrillation easily occurs due to rubbing between fibers or rubbing against other objects, the fibers are easily worn, and therefore the strength that was superior when the process such as twisting is significantly reduced, so-called holding strength Shows the disadvantage of low rates.

In order to solve these problems, attempts have been made to improve by a physical method such as a twisting method and a twisting condition, but there is still no proposal for the relationship with fiber surface characteristics. Is the current situation.

As a method for improving the surface properties of the fiber, which has been heretofore used, for example, a method of protecting the fiber surface by applying a solid wax component to the fiber surface or coating the fiber surface with a fluororesin or the like is used. However, according to these methods, in the post-processing step, fixed solid components fall off and are deposited on the yarn guide, which causes various troubles. However, the processing speed is limited, which is not preferable for commercial production, and since the fibers are resin-coated in a bundled form, the movement of the single fibers is restrained and the yarn as a whole becomes hard, and therefore the tenacity retention rate is high. It has the drawback that the improvement of

<Purpose of the Invention> The present invention has conducted extensive studies on a method for greatly improving the surface properties of fibers while maintaining the excellent properties of conventional aramid fibers, and as a result, modified the surface of fibers with a specific compound. This has led to the present invention by discovering the important fact that the abrasion resistance between fibers can be increased remarkably than ever before.

That is, the object of the present invention is to provide a function having a surface having extremely excellent abrasion resistance in applications such as cords and ropes which are used after being twisted, and therefore a surface having high strength retention after twisting. A modified wholly aromatic polyamide fiber is provided.

<Structure of the Invention> That is, the present invention shows a liquid at a temperature of 15 ° C. or higher on the surface of wholly aromatic polyamide fiber in which a solid cation-exchangeable and non-ion-adsorbing inorganic compound is fixed on the fiber surface. Aliphatic lubricant and / or silicone having a coating composed of a polyoxyalkylene-containing aliphatic polyester compound having a molecular weight of 3000 or more, which is incompatible with the polyester compound and has a molecular weight of 900 or less on the coating. A surface-modified wholly aromatic polyamide fiber having a layer of a system lubricant.

Here, the cation-exchangeable and non-ion-adsorbing inorganic compound is a compound having an ability to exchange cations and an ability to adsorb non-ions, specifically, silica-alumina, silica-magnesia, bentonite, Kaolin, Fuller's earth, acid clay, activated clay, montmorillonite, baitsite, talc, etc. These cation exchangeable and non-ion-adsorbing inorganic compounds are fixed to the fiber surface in a solid state. The size of the compound (particle) is approximately 0.
Those having a size of about 01 to 5 μm are used. In the present invention, the term "fixation" means that the substance is not detached at all by a washing treatment in a violent state or by immersion in a solvent.

The inorganic compound particles can be fixed to the fiber surface by, for example, pressing the inorganic compound particles against the fiber surface in a state where the fiber surface is softened, biting the fiber surface, and then solidifying the fiber. That is, cation-exchangeable and non-ion-adsorptive inorganic compounds are sprayed onto the wholly aromatic polyamide fibers immediately after spinning, or the total fragrance is obtained by suspending cation-exchangeable and non-ion-adsorptive inorganic compound particles in water. A method is used in which the group-polyamide fiber is dipped to adhere the inorganic compound particles to the fiber surface, and then hot stretching or heat treatment is performed at a temperature not lower than the second-order transition point of the wholly aromatic polyamide fiber.

The wholly aromatic polyamide fiber is, for example, one made of paraphenylene terephthalamide or a copolymer thereof composed of a predetermined aromatic dicarboxylic acid and aromatic diamine, but is not particularly limited.

The polyoxyalkylene-containing aliphatic polyester compound is one of polyalkylene glycols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol or a copolymer thereof, and capric acid, lauric acid, myristic acid, palmitic acid, An ester with a monobasic acid such as stearic acid and oleic acid, or one or more kinds of dibasic acids such as adipic acid, azelaic acid and sebacic acid.

Here, it particularly refers to a liquid having a molecular weight of 3000 or more and a temperature of 15 ° C. or more.

If the molecular weight is 3000 or less, it is not possible to obtain the desired high abrasion resistance strength of the fiber surface here, and if it is not liquid at a temperature of 15 ° C or more, it is not only difficult to handle when applied onto the fiber. In the post-processing of the fibers, it is not preferable because it causes stains such as so-called scum on the thread guides due to solid matter.

Such a high molecular weight ester compound has a high viscosity due to its molecular structure, has a strong liquid film strength, and enhances lubricity under extreme pressure. Therefore, even if a high contact pressure is applied between the fibers due to the action of the twisted yarn or the like, there is a degree of freedom between the fibers. That is, the inter-fiber frictional force is reduced, the abrasion resistance strength of the fiber surface is increased, and the strength reduction due to the twisted yarn is suppressed.

However, on the other hand, since the fiber having the generated film has a high viscosity, the running friction becomes high when traveling on the yarn guiding guides, and the single yarn is picked up by the yarn guiding guides to generate fuzz. Since it causes various troubles, it cannot be used alone. Therefore, in the case of the present invention, it is necessary to use a low friction lubricant together.

When two kinds of compounds are used in combination, they are usually compatible with each other, unless they have no affinity for each other, and even if a low friction lubricant is used, the effect is not exhibited. Therefore, the lubricant applied in the present invention is required to be incompatible with the polyoxyalkylene-containing aliphatic polyester compound.

Further, in the case of the present invention, since the fiber surface has been modified in advance to be cation-exchangeable and non-ion-adsorptive, the high molecular weight polyoxyalkylene-containing aliphatic polyester compound is preferentially adsorbed on the fiber surface, The low friction lubricant is formed on the coating to achieve the purpose of reducing the running friction.

Thus, it is an important point of the present invention that the extreme pressure lubricant composed of the high molecular weight polyoxyalkylene-containing aliphatic polyester compound and the low friction lubricant have a two-layer structure on the fiber. Is.

The lubricant incompatible with the polyoxyalkylene-containing polyester compound used in the present invention is an aliphatic lubricant having a molecular weight of 900 or less and / or a silicone lubricant.

Aliphatic lubricants include esters of mineral oil alcohols and basic acids, or natural oils and fats, but preferably used as low friction lubricants are octyl palmitate, oleyl oleate, and isostearyl oleate. It is an ester of a monohydric alcohol with a monobasic acid.

In this case, when the molecular weight exceeds 900, the viscosity is high, and therefore it cannot be used as a low friction lubricant.

In addition, compounds other than aliphatic compounds, such as compounds having an aromatic ring, also have high friction, and therefore cannot be used.
As the non-aliphatic lubricant, a silicone lubricant represented by dimethyl silicone can be used. Among these, low viscosity dimethyl silicone having a viscosity of 300 cst (at 30 ° C.) or less is preferable for low friction. The treatment of the high molecular weight polyoxyalkylene-containing aliphatic polyester compound (A) and the aliphatic lubricant (B) having a molecular weight of 900 or less and / or the silicone lubricant on the fiber is performed in advance as described above. After fixing the cation-exchangeable and non-ion-adsorptive inorganic compound on the fiber, the compound (A) is first applied to form a film of the compound on the surface of the fiber, and then a lubricant ( Although B) may be applied, the compound (A) and the lubricant (B) may be applied simultaneously. Even if they are applied simultaneously, the compound (A) is adsorbed on the fiber side for the above-mentioned reason, and as a result, the same effect as when applied twice is obtained.

In addition, in applying these agents, such an agent may be treated as an aqueous fiber treatment liquid containing water, or as a non-aqueous fiber treatment liquid containing an agent in a solvent containing substantially no water. As a means for further applying, any known means such as an oiling roller, a metering oiling nozzle, and a spray may be used.

In addition to the compound (A) of the present invention and the lubricant (B), other compounds such as an antistatic agent may be mixed with the fiber treating agent, if necessary.

The amount applied as a treating agent for fibers is 0.1 with respect to the weight of fibers.
-5% by weight is preferred. The application amount is preferably in the range of about 0.1 to 2% by weight of each of the compound (A) and the lubricant (B) based on the weight of the fiber.

<Effects of the Invention> The present invention does not increase running friction when traveling on a yarn guide in a fiber processing step, and thus does not cause fluff or yarn breakage during traveling, and is wholly aromatic. It is intended to provide a wholly aromatic polyamide fiber having a high abrasion resistance on the surface while maintaining the excellent properties such as high strength and high modulus inherent in the polyamide fiber.

<Examples> The present invention will be specifically described below with reference to Examples.

In addition, the characteristic value used for evaluation in this invention was measured according to the following method.

(1) Abrasion resistance of fiber surface As shown in Fig. 1, disks 1,2 rotating both ends of fiber Y of 1500 denier 1000 filaments at constant rotation (500 rpm)
Then, the fibers are passed through pulleys 3 and 4 at the point A at the point A so that the number of twists is 2 turns, and the fibers are crossed and then applied to the pulley 5 with a load 6 of 500 g.

The crossing angle of the fiber at point A was 40 °, and the reciprocating stroke length of the fiber was 50 mm.

In this way, the fibers were repeatedly rubbed repeatedly, and the time until rubbing and cutting was expressed in seconds, and the abrasion resistance was evaluated.

(2) Running friction coefficient As shown in FIG. 2, the fiber Y unwound from the raw yarn package 1 passes through the yarn guide 2 and the tension compensating center 3 of S-shape adjusts the tension T ₁ to 20 g to obtain the surface roughness. The cylindrical friction body 4 of 60φ of 11S is contacted at a contact angle of 180 °, and its output side tension (T ₂ )
After the measurement, the yarn bundle was run through the rotating roller 5 having a surface speed of 300 m / min. The friction coefficient at this time is μ = (1 /
π) ln (T ₂ / T ₁ ).

(3) Fiber tenacity retention rate (i) Using an Instron tensile tester, a fiber sample having an initial length of 25 cm was measured for tensile breaking strength under an atmosphere of 20 ° C. and 65% RH at a tensile speed of 10 cm / min. From this, the fiber strength (g / de) was obtained.

(Ii) The strength (g / de) of the cord was obtained by measuring the double-twisted cord, which was twisted for 40 turns per 10 cm under twisting and twisting using the Instron tensile tester, under the same measurement conditions as in (i). .

The strength retention was determined from the ratio of the cord strength to the fiber strength.

(4) Comprehensive Judgment The results evaluated by the above measurement methods were comprehensively evaluated, and good to bad were indicated by 〜 to ×.

Examples 1 to 5 and Comparative Examples 1 to 6 Para wholly aromatic polyamide composed of terephthalic acid dichloride, paraphenylenediamine and 3,4'-diaminodiphenyl ether was spun out and washed with water repeatedly, and then an aqueous dispersion of bentonite was attached after washing with water. A cation exchangeable and nonion-adsorptive wholly aromatic polyamide fiber (1500 denier 1000 filaments) having 0.42% of non-falling bentonite on the fiber surface was obtained by heat drawing at 500 ° C. at most.

Immediately after the stretching of the wholly aromatic polyamide fiber, a 15% aqueous emulsion having the composition shown in Table 1 was applied so that the solid content was 3.5% with respect to the weight of the fiber, dried and wound.

Table 2 shows the results of the evaluation of the obtained fibers by the above evaluation method.

Comparative Example 6 in Table 2 shows the results of comparative evaluation in the same manner by adding the oil agent of Example 1 to a fiber to which the cation-exchangeable and non-ion-adsorbing inorganic compound was not added as the wholly aromatic polyamide fiber.

From these results, it is clear that the present invention has a remarkable effect.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of an apparatus for measuring abrasion resistance of a fiber surface.
Reference numerals 1 and 2 are discs, 3 and 4 are pulleys, 6 is a load, A is a fiber intersection, and A is a fiber. FIG. 2 is a schematic view of an apparatus for measuring a running friction coefficient of a fiber. 1
Is a package, 2 is a yarn guide, 3 is a tension compensator, 4 is a cylindrical friction body, 5 is a rotating roller, and T ₁ and T ₂ are tension measuring devices.

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Claims (1)

[Claims] 1. A polyoxygen having a molecular weight of 3000 or more which is liquid at a temperature of 15 ° C. or higher on the surface of wholly aromatic polyamide fiber in which a solid cation-converting and non-ion-adsorbing inorganic compound is fixed on the fiber surface. Having a coating composed of an alkylene-containing aliphatic polyester compound, a layer of an aliphatic lubricant and / or silicone lubricant having a molecular weight of 900 or less, which is incompatible with the polyester compound, is formed on the coating. A surface-modified wholly aromatic polyamide fiber having.