KR101277157B1 - Method of manufacturing aramid raw cord - Google Patents

Abstract

The present invention relates to a method for producing aramid twisted yarn, when the aramid multifilament is twisted in a twisting machine by attaching at least one driving guide (2) having a coefficient of friction of 0.25 or less in the twisting machine to twist the aramid multifilament Characterized in that.

The aramid plywood of the present invention is used as a raw cord (Taw cord) to produce an aramid tire cord by treating the adhesive for the tire cord.

The present invention effectively prevents the occurrence of the fur in the aramid multifilament during twisting, maintaining the strength retention rate after the twisted weaving at 95% or more.

Aramid, Plywood, Cord, Strength, Mou

Description

Method of manufacturing aramid composite yarn {Method of manufacturing aramid raw cord}

The present invention relates to a method for producing aramid twisted yarn used in aramid tire cord.

Aramid ply twisted yarn is obtained by adding the upper and lower edges (or lower and upper edges) to the aramid multifilaments, and these are also twisted yarns, also known as a raw cord for a tire cord.

The tire is a composite of fiber / steel / rubber, constituting it, that is, steel and fiber cord serve to reinforce rubber and form a basic skeletal structure in the tire. In other words, compared to the human body is a bone-like role.

The performance required for the cord as a tire reinforcement is fatigue resistance, shear strength, durability, resilience and adhesion to rubber. Therefore, a cord of appropriate material is used according to the performance required for the tire.

Commonly used materials for the cord are rayon, nylon, polyester, steel, and aramid.

Recently, as high-speed driving performance is required for tires, aramid fibers having high strength and high modulus, that is, aramid multifilament, have been widely used as materials for tire cords.

Here, aramid multifilament represents a bundle of spun aramid monofilaments.

The aramid tire cord gives the upper edge (Z edge) (or the lower edge (S edge)] to the aramid multifilament, and then the lower edge (S edge) again to the upper strand (or the lower edge (S edge)) of the aramid filament 2 strands as described above. Sangyeon (Z-yeon)] Aramid twisted yarns are prepared by twisting with twisting, and then immersed in an adhesive solution for tire production, and then dried and heat-treated.

In the present invention, the step of weaving them while twisting the aramid filament as described above is referred to as a "ply twisted yarn process".

Although the aramid multifilament has excellent strength and modulus in its longitudinal direction, it is very vulnerable to a force applied in a direction perpendicular to its longitudinal direction, so that a large amount of wool is generated by friction with the guide during the twisted yarn weaving process. The strength retention rate after the twisted yarns is lowered to a level of less than 95%, thereby causing various problems such as various properties such as durability in the tire.

Therefore, it is very important to minimize friction between the guide and the aramid multifilament passing through the aramid multifilament process of the aramid multifilament.

In the conventional twisted yarn aramid multifilament process, one or more fixed roller guides, such as ceramic materials, having a high coefficient of friction of 0.40 to 0.45 were attached to the twisted yarn, so that the aramid multifilament was twisted and twisted. There was a problem in that the friction between the severe a large amount of moor generated in the aramid multifilament.

The present invention effectively prevents the occurrence of the occurrence of the swell in the aramid twisted yarn by reducing the friction between the guide and the aramid multifilament passing through the aramid twisted yarn process of the aramid multifilament, the aramid twisted yarn of 95% or more strength retention after the twisted yarn It provides a manufacturing method.

In the method of manufacturing aramid conjugated twisted yarn according to the present invention, when aramid multifilaments are twisted while twisting in a twisting machine, the aramid multifilament is added to at least one driven guide (2) having a friction coefficient of 0.25 or less. It is characterized by the speaker.

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

The filament bundle produced by spinning is referred to as 'multi filament', and a raw cord manufactured by the upper and lower edges (or lower and upper edges) of the multifilament is referred to as a 'ply-twisted yarn', and a tire cord is attached to the twisted yarn. Deep cords in the finished state treated with a solvent adhesive are called "tire cords" or "codes".

Looking specifically at the manufacturing method of aramid raw twisted yarn (Aramid raw cord) according to the present invention, as shown in Fig. When the two strands are twisted and then twisted while giving the twisted twist (S-yeon) twisted in the clockwise direction as shown in FIG. 3 to produce aramid twisted yarn as shown in FIG. Is used by mounting at least one drive guide (2) having a diameter of 0.25 or less.

1 is a schematic diagram of a step of twisted yarns of an aramid multifilament, and FIGS. 2 to 3 are diagrams showing definitions of upper edge (Z edge) and lower edge (S edge), respectively.

The aramid multifilament being dissipated from the aramid multifilament bobbins 1 is rotated by the spindle 7 through a traveler 6 which is rotated by yarn tension on the ring 5 by the feed roller 3. It is wound up on the twisted yarn winding bobbin 4.

The driven guide 2 is a self-rotating roller type, fine protrusions are formed on a surface thereof, and the material is preferably one selected from chromium oxide and ceramic.

When the friction coefficient of the driven guide 2 exceeds 0.25, a large amount of moor is generated by applying an excessive friction force to the aramid multifilament passing therethrough.

The friction coefficient is measured by a friction coefficient measuring instrument of model name 9000 of Japan TTS UNLIMITED.

The drive type guide 2 is preferable to prevent the occurrence of moor by reducing the contact area with the aramid multifilament passing through the fine protrusions formed on the surface.

The driven guide 2 is a roller type that rotates itself by a separate power, and can significantly reduce the frictional force applied to the aramid multifilament passing through the conventional guided roller type guide.

It is preferable that the number of twists of each of the upper edge (Z edge) and the lower edge (S edge) is 20 to 60 times / 10 cm, respectively.

When the number of twists is less than 20 times / 10cm, the strength is low because the number of twists is low but the cutting elongation is very low, resulting in poor fatigue characteristics of the cord and poor adhesion due to the low surface area.

If the number of twist exceeds 60 times / 10 cm may cause a problem that the strength of the tire cord is reduced due to excessive twist.

The aramid multifilament is a wholly aromatic polyamide filament composed of poly (para-phenylene terephthalamide), as shown in Figure 4 containing an aromatic diamine and an aromatic dieside chloride N-methyl-2-pyrrolidone Polymerizing in a polymerization solvent to produce an aramid (fully aromatic polyamide) polymer; Dissolving the polymer in a concentrated sulfuric acid solvent to prepare a spinning stock solution; Spinning the undiluted solution from the spinneret to pass the radiated spine through a non-coagulant fluid layer into a coagulation bath to form a multifilament; And it may be produced by a manufacturing method comprising a step of producing aramid multifilament fibers through the process of washing, drying and heat treatment the multifilament.

4 is a process schematic diagram of producing the aramid multifilament fibers.

In this case, the aromatic diamine is P-phenylenediamine and the like, and the aromatic dieside chloride is terephthaloyl chloride and the like.

The polymerization solvent is N-methyl-2-pyrrolidone or the like in which calcium chloride is dissolved.

The intrinsic viscosity of the aramid (fully aromatic polyamide) polymer is 5.0 or more is good for improving the strength and elastic modulus of the filament.

The aramid polymer may be prepared using known polymerization conditions disclosed in US Pat. No. 3,869,429, etc., but the present invention does not specifically limit the polymerization conditions of the aramid polymer.

One example of preparing the polymer is a solution of 1 mole of para-phenylenediamine dissolved in N-methyl-2-pyrrolidone containing about 1 mole of calcium chloride and 1 mole of terephthaloyl chloride in a polymerization reactor. After the addition, it is stirred to prepare a gel polymer, which is ground, washed with water and dried to prepare a fine powder aramid polymer. At this time, the terephthaloyl chloride may be added to the reactor for polymerization divided into two stages.

It is preferable that the concentration of concentrated sulfuric acid used in preparing the spinning stock solution is 97% to 100%, and chlorosulfuric acid, fluorosulfuric acid, and the like may also be used.

At this time, when the concentration of sulfuric acid is less than 97%, the solubility of the polymer is reduced and the liquid crystalline expression of the anisotropic solution becomes difficult. Therefore, it is difficult to manufacture a spinning solution having a constant viscosity, which makes it difficult to control the process during spinning and to provide mechanical properties of the final fiber. Can be degraded.

On the other hand, if the concentration of the concentrated sulfuric acid exceeds 100%, gwari (過離) because in oleum containing SO _3, as well as undesirable phase handled becomes an SO ₃ over takes place is partly dissolved in the polymer spinning solution to the inadequate and In addition, even if the fiber is obtained by spinning, there may be a problem that the internal structure of the fiber is not dense, the appearance is not gloss, and the speed of sulfuric acid diffused into the coagulation solution is lowered, thereby lowering the mechanical properties of the fiber.

On the other hand, the concentration of the polymer in the spinning stock solution is preferably 10 to 25% by weight for the fiber properties.

However, the present invention does not specifically limit the concentration of concentrated sulfuric acid and the concentration of the polymer in the spinning stock solution.

The non-coagulating fluid layer may mainly be an air layer or an inert gas layer.

The length of the non-coagulating fluid layer, that is, the distance between the bottom surface of the spinneret 40 and the surface of the coagulating liquid contained in the coagulating liquid bath 50 is preferably 0.1 to 15 cm to improve the properties of the radioactive or filament.

The coagulant in the coagulant bath 50 may overflow. As the coagulating solution, water, brine or an aqueous sulfuric acid solution having a concentration of 70% or less is used.

Next, the formed filaments are washed with water, dried and heat treated to produce wholly aromatic polyamides.

At this time, the spinning winding speed is set to 300 to 1500 m / min.

The strength of the aramid multifilament used in the present invention is 10 ~ 25g / d, when less than 10g / d, the strength is low, it is difficult to support the car load when applied as a tire cord, the problem of the performance of the tire is impossible, 25g In the case of exceeding / d, problems with inefficiency may arise due to over-prolonged physical properties.

In addition, the cut elongation of the aramid multifilament is 2 ~ 6%, if less than 2% due to the low cutting elongation occurs a problem that the fatigue characteristics are insufficient to be applied to the tire cord, when the stability exceeds 6% form stability This scarce problem can occur.

In addition, as the modulus of the aramid multifilament 400 ~ 750g / d, less than 400g / d, due to the low modulus, a problem that the lack of support capacity for high-speed driving occurs during tire manufacturing, if the exceeding 750g / d Due to the high modulus, problems may arise that make tire molding difficult.

Preferably, the total fineness of the aramid tire cord is 800 to 10,000 denier, and the aramid multifilament preferably has a total fineness of 400 to 5,000 denier and is composed of 500 to 1,200 aramid monofilaments. Moreover, it is preferable that the single yarn fineness of the said aramid monofilament is 1-2 denier.

Various physical properties of the aramid multifilament is measured by the following method.

Strength (g / d) and elongation at break (%)

According to ASTM D-885 test method, the strength (g) at the time of fracture of the sample yarn was measured using a sample yarn having a length of 25 cm in an Instron Engineering Corp. (Canton, Mass), and then the sample yarn was denier. The strength was calculated by dividing. Elongation at break was calculated as the ratio of the length of the sample yarn to the length of the sample yarn until the sample yarn was broken. The strength and the elongation at break were taken as the average value after five tests. At this time, the tensile speed was 300 mm / min, and the initial load was 1/130 g of fineness.

Modulus (g / d)

The stress-strain curve of the sample yarn is obtained under the above-described strength measurement conditions, and then calculated from the slope on the stress-strain curve.

The aramid plywood according to the present invention is immersed in a conventional resorcinol-formaldehyde-latex (RFL) solution so that the pick-up rate is 3 to 12% by weight based on the aramid plywood, followed by drying and heat treatment to aramid tire cord It can be used to make.

Examples of the RFL adhesive solution is 2.0% by weight of resorcinol, 3.2% by weight of formalin (37%), 1.1% by weight of sodium hydroxide (10%), styrene / butadiene / vinylpyridine (15/70/15) rubber (41) %) RFL adhesive solution comprising 43.9% by weight, and water.

When the pickup rate is less than 3% by weight, the adhesion with rubber may be lowered. When the pickup rate is higher than 12% by weight, the penetration rate of the RFL solution (immersion liquid) in the cord may be too high, resulting in low strength and low fatigue characteristics. Various physical properties, such as becoming, can be reduced.

It is preferable to dry for 10 second-400 second at 105-200 degreeC which is the said drying process, and heat processing may be performed for 10 second-400 second at 105-300 degreeC.

When the drying time and the heat treatment time are respectively lower than the above ranges, or when the drying temperature and the heat treatment temperature are respectively below the above ranges, a low adhesive force may occur.

When the drying time and the heat treatment time each exceed the above ranges, or when the drying temperature and the heat treatment temperature respectively exceed the above ranges, the adhesive force is reduced due to excessive thermal history. The problem of low physical properties may occur.

The aramid-ply twisted yarn of the present invention produced by the above method is less in the occurrence of cow hair, the strength retention rate after the twisted yarn is 95% or more, and excellent physical properties such as durability in the tire at high speed.

· After the speaker  Strength maintenance

Using the method of measuring the strength of aramid multifilament described above, the strength of the aramid multifilament before the twist treatment and the aramid twisted yarn of the twisted yarn were obtained, respectively, and the measured values were substituted into the following equation to calculate the strength retention rate after the twisting.

The present invention has an effect of effectively preventing the occurrence of the cow in the aramid twisted yarn by minimizing the friction between the guide of the twisting machine and the aramid multifilament passing through the aramid twisted yarn manufacturing.

Aramid plywood yarn produced by the present invention has a small amount of wool and maintains high strength even after the twisted yarn is excellent in durability and shape stability in the tire during high-speed driving.

Hereinafter, preferred embodiments of the present invention will be described. However, the following examples are only preferred embodiments of the present invention, and the present invention is not limited to the following examples.

Example  One

An aromatic diamine solution was prepared by maintaining 1,000 kg of N-methyl-2-pyrrolidone at 80 ° C. and dissolving 80 kg of calcium chloride and 48.67 kg of para-phenylenediamine.

The aromatic diamine solution was introduced into the polymerization reactor 20, and at the same time, a molten terephthaloyl chloride of an equimolar amount of para-phenylenediamine was simultaneously introduced into the polymerization reactor 20, followed by stirring them to have an intrinsic viscosity of 6.8. Poly (para-phenyleneterephthalamide) polymer (aramid polymer) was prepared.

Next, the prepared aramid polymer was dissolved in 99% concentrated sulfuric acid to prepare an optically anisotropic radiation stock solution having a polymer content of 18% by weight.

Next, after spinning the spinning stock solution prepared as described above at a spinning winding speed of 1,000 m / min through the spinneret 40 as shown in Figure 3, the radiated spinning material 7 mm air layer (non-coagulation) Fluid layer), and then passed through a coagulation bath 50 containing a sulfuric acid aqueous solution (coagulant) having a sulfuric acid concentration of 13% to prepare aramid multifilament.

Next, the multifilament formed as described above was washed with water and dried, followed by repeated five times of heat treatment at 550 ° C. for 0.3 seconds to prepare aramid multifilament.

The number of filaments of the aramid multifilament yarn produced by the above method is 1000, the average fineness is 1.5 d, the strength is 22.3 g / d, the modulus is 714 g / d, the elongation at break is 3.2%.

The aramid multifilament prepared above is made of chromium oxide, has fine protrusions formed on the surface thereof, has a coefficient of friction of 0.20, and two self-rotating roller type guides (2) as shown in FIG. Using Cable & Cord 3 type twister (CC Twister, Allma Co.) installed between (1) and feed roller (3) Again twist 30 times / 10 ㎝ twisted (S-yeon) by twisting them to prepare aramid yarn (Aramid raw cord).

As a result of evaluating the strength retention after the twisted yarn twisted yarn of the aramid twisted yarn manufactured as described above, it was 97%.

Comparative Example  One

Instead of the driven guide 2 of Example 1, the material is ceramic, there are no micro projections on the surface, and two fixed roller type guides 2 having a coefficient of friction of 0.40 are aramid multifilament bobbin 1 as shown in FIG. Aramid tire cord was prepared in the same manner as in Example 1, except that it was installed between and the supply roller (3).

As a result of evaluating the strength retention rate after the twisting of the aramid-ply twisted yarn thus manufactured by the aforementioned measuring method, 92% was obtained.

1 is a process schematic diagram of twisting aramid multifilament.

2 to 3 show the definition of the upper and lower edges.

4 is a process schematic diagram of making aramid multifilament fibers.

Claims (10)

In preparing aramid twisted yarn by twisting aramid multifilaments in a twisting machine twisting, the at least one driving guide (2) having a friction coefficient of 0.25 or less is attached to the twisting machine to the aramid multifilament Aramid conjugated yarn manufacturing method. The method of claim 1, wherein the driven guide (2) is a roller type that rotates itself. The method of claim 1, wherein fine projections are formed on the surface of the driven guide (2). The method of claim 1, wherein the driving guide (2) is made of chromium oxide and ceramics. A method according to claim 1, characterized in that the driven guide (2) is mounted between the aramid multifilament bobbin (1) and the feed roller (3). The method of claim 1, wherein the aramid is poly (para-phenylene terephthalamide). The method of claim 1, wherein the aramid multifilament has a strength of 10 to 25 g / d, an elongation at break of 2 to 6%, and a modulus of 400 to 750 g / d. The method of claim 1, wherein the total fineness of the aramid multifilament is 400 to 5,000 denier. The method of claim 1, wherein the aramid multifilament is composed of 500 to 1,200 aramid monofilaments. 7. The method for producing aramid twisted yarn according to claim 6, wherein the single yarn fineness of the aramid monofilament is 1 to 2 denier.

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