KR101277154B1 - Aramid tire cord and method of manufacturing the smae - Google Patents

Abstract

The present invention relates to an aramid tire cord and a method of manufacturing the same, after the high-strength and high modulus aramid filaments are fused and immersed in a conventional RFL solution at a pickup rate of 3 to 12% by weight, and excellent in high-speed driving by drying and heat treatment Aramid tire cords are produced that exhibit performance.

The aramid tire cord of the present invention has a dip strength of 10 to 23 g / d, an elongation at break of 3 to 10%, and a rubber adhesion force of 10 kg or more, thereby exhibiting excellent morphological stability and thermal stability in the tire.

Aramid, cord, strength, elongation at break, adhesion, shape stability, thermal stability.

Description

Aramid tire cord and method of manufacturing the smae

The present invention relates to an aramid tire cord and a method for producing the same.

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.

Generally used tire cord material is nylon, polyester, rayon and the like. These materials are limited in size and use, etc. of the tires used due to their advantages and disadvantages.

Nylon fiber has high tensile elongation and high strength, and is mainly used for tires used on curved roads such as heavy trucks and unpaved roads. However, the nylon fiber is not suitable for a tire for a passenger car in which concentrated heat accumulation occurs inside the tire, and a low modulus is used to travel at high speed or require a ride comfort.

Polyester fiber has better shape stability and price competitiveness than nylon, and strength and adhesion are improved due to continuous research, and its usage is increasing in the tire cord field. However, it is not suitable for high-speed running tires because of limitations in heat resistance and adhesive strength.

Rayon fiber, a regenerated cellulose fiber, exhibits excellent strength retention and shape stability at high temperatures. Therefore, rayon fiber is known as an optimal tire cord material. However, due to the strong deterioration due to moisture, thorough moisture management is required during tire manufacturing, and due to the nonuniformity in yarn manufacturing, the rate of defective products is high. Above all, its price / performance ratio is very low compared to other materials, and it is mainly applied only to high speed or expensive tires.

An object of the present invention is to provide a method for producing aramid tire cord having excellent shape stability and thermal stability by applying aramid multifilament having high strength and modulus.

It is still another object of the present invention to provide an aramid tire cord, which is manufactured by the above manufacturing method and has higher strength and modulus than conventional tire cords.

The aramid tire cord according to the present invention comprises an aramid multifilament, has a dip strength of 10 to 23 g / d, an elongation at break of 3 to 10%, and a rubber adhesive force of at least 10 kg.

In the method for preparing aramid tire cord according to the present invention, the aramid multifilament having the following physical properties is given by twisting the upper edge (Z lead) and then twisted while giving the lower strand (S lead) twist to the two strands stranded to produce aramid twisted yarn After soaking, the solsolol-formaldehyde-latex (RFL) solution was immersed in a pickup rate of 3 to 12% by weight based on the aramid twisted yarn, and dried at 105 to 200 ° C for 10 to 400 seconds, and then 105 to Heat-treating at 300 ° C. for 10 seconds to 400 seconds.

Physical Properties of Aramid Filaments

-Strength: 10 ~ 25g / d

-Elongation at break: 2 ~ 6%

Modulus: 400 ~ 750g / d

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 at an example of a method for manufacturing an aramid tire cord according to the present invention, first using the aramid multifilament having the following physical properties, such as a tire cord Alma twister as shown in Fig. The twisted twisted yarn is then twisted while giving the twisted two strands with twisted twisting direction as shown in FIG.

1 to 2 are diagrams showing definitions of upper edge (Z edge) and lower edge (S edge), respectively.

At this time, the twist number of each of the upper (Z) and the lower (S) is preferably 20 to 60 times / 10 cm.

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 3 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 a spinneret to pass the spun spine through a non-coagulant fluid layer into a coagulation bath to form a multifilament; And it can 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.

3 is a process schematic drawing of 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.

The concentration of concentrated sulfuric acid used in the production of the spinning stock solution is preferably 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 stock solution with a constant viscosity, which makes it difficult to control the process during spinning and the 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, a problem arises that the tire performance is not efficient due to sufficient 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 lacking problem occurs.

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 The high modulus creates a problem that makes tire molding difficult.

It is preferable that 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.

Next, the aramid-ply-twisted yarn spliced as described above is immersed in a conventional resorcinol-formaldehyde-latex (RFL) solution so that the pickup ratio is 3 to 12% by weight based on the aramid-ply-twisted yarn. Bath dipping can be used.

Examples of RFL adhesive solution used in the present invention include 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) An RFL adhesive solution comprising 43.9% by weight of rubber (41%), and water is used.

In the present invention, as an example of the adhesive liquid for the adhesion between the aramid cord and the rubber can be prepared and used as described above, the above examples are intended to more clearly understand the present invention, to limit the scope of the present invention It is not.

When the pickup rate is less than 3% by weight, the adhesive strength with rubber is lowered. When the pickup rate is more than 12% by weight, the penetration rate of the RFL solution (immersion liquid) in the cord is too high, the strength is low, and the fatigue property is lowered. Various physical properties of are lowered.

Next, the yarn in which the RFL solution is immersed is dried at 105 to 200 ° C. for 10 seconds to 400 seconds, and then heat-treated at 105 to 300 ° C. for 10 seconds to 400 seconds to prepare an aramid tire cord.

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, the problem of low adhesion occurs.

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 is generated.

In the drying process, the moisture present in the aramid multifilament is dried, and in the heat treatment process, the impregnation solution is reacted to impart adhesion to the tire cord.

The aramid tire cord of the present invention prepared by the above method has a dip strength of 10 to 23 g / d, an elongation at break of 3 to 10%, and an adhesive force of 10 kg or more.

In addition, the aramid tire cord according to the present invention has a median elongation of 0.3 ~ 1.5% elongation rate change rate measured under a load of 6.75kg, dry heat shrinkage is 0.3 ~ -1.0% or less.

Various physical properties of the aramid tire cord are measured by the following method.

Rubber adhesion

It is measured by the H-test method based on the ASTM D 4776-98 method. Using the rubber composition shown in Table 1, both ends of the deep cord were embedded in 9.5 mm rubber lumps, and the adhesive test pieces were made at 9 mm intervals between the rubber lumps at both ends. After vulcanizing for a minute, the maximum load at which the separation between the rubber and the cord occurs with Instron was measured to evaluate the adhesive force. The adhesive force (kgf) was evaluated.

Raw material name Addition amount (part) Natural rubber 100 Zinc Oxide 3 Carbon Black 29.8 Stearic acid 2.0 Pin tar 7.0 Mercapto Benzothiazole 1.25 Sulfur (S) 3.0 Diphenyl Guanidine 0.15 Phenyl β-napthalamine 1.0

· Cord  Strength (g / d) and Elongation (%)

According to ASTM D-885 test method, the strength of the cord divided by the denier of the cord was determined by dividing the breaking strength of the cord measured at a sample length of 250 mm and a tensile rate of 300 m / min using an Instron Engineering Corp. (Instron Engineering Corp, Canton, Mass). Elongation at break was calculated as the ratio of the length of the cord to its original length until the cord broke.

· Dry heat shrinkage (%)

After treatment under a load of 0.01 g / d for 2 minutes at 180 ° C with a length (L1) measured under a constant load of 0.01 g / d using a shrinkage behavior tester (manufactured by TestRite) according to ASTM D 4974-04 Dry heat shrinkage was measured using the ratio of length (L2).

Medium elongation (%)

According to the ASTM D-885 test method, it is expressed as the change in elongation length at the point of 6.75 kg load in the elongation load graph measured by an Instron Engineering Corp. (Instron Engineering Corp, Canton, Mass).

In the present invention, matters other than those described above can be added or subtracted as required, and therefore, the present invention is not particularly limited thereto.

Aramid tire cord according to the present invention exhibits high strength, high modulus and low shrinkage characteristics, and has an effect of greatly improving the shape stability and thermal stability of the tire at high speeds.

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 1

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) After passing through the fluid layer), and subsequently passed through the coagulation bath 50 containing a sulfuric acid aqueous solution (coagulant) of 13% sulfuric acid concentration 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 prepared aramid multifilament was staged using a cable & Cord 3 type twister (CC Twister, Allma Co.) 30 times / 10 cm twisted (Z length), and the stranded two strands again 30 times / 10 times The twisted yarns of cm were rolled (S rolled), and these were spliced together to prepare a cord dough.

As described above, the raw material of the cord is 2.0% by weight of resorcinol, 3.2% by weight of formalin (37%), 1.1% by weight of sodium hydroxide (10%), and styrene / butadiene / vinylpyridine (15/70/15) rubber (41%). The RFL adhesive solution containing 43.9% by weight, and water was immersed so that the pick-up rate was 5% by weight based on the aramid twisted yarn, dried at 150 ° C. for 60 seconds, and then heat-treated at 250 ° C. for 120 seconds.

Various physical properties of the aramid tire cord thus prepared were as shown in Table 2.

Example 2

Aramid tire cord was prepared in the same manner as in Example 1, except that the number of twists of the upper and lower edges was changed to 40 times / 10 cm.

Various physical properties of the aramid tire cord thus prepared were as shown in Table 2.

Example  3

An aramid tire cord was prepared in the same manner as in Example 1 except that the number of twists of each of the upper and lower edges was changed to 50 times / 10 cm.

Various physical properties of the aramid tire cord thus prepared were as shown in Table 2.

Example 4

Aramid tire cord was prepared in the same manner as in Example 1 except that the heat treatment conditions were changed to 90 seconds at 260 ° C., and the RFL pickup rate was changed to 6 wt%.

Various physical properties of the aramid tire cord thus prepared were as shown in Table 2.

Comparative Example 1

Aramid tire cord was prepared in the same manner as in Example 1, except that the number of twists of each of the upper and lower edges was changed to 20 times / cm.

Various physical properties of the aramid tire cord thus prepared were as shown in Table 2.

Comparative Example 2

Aramid tire cord was prepared in the same manner as in Example 1 except that the RFL pickup rate was changed to 15% by weight.

Various physical properties of the aramid tire cord thus prepared were as shown in Table 2.

Aramid tire cord physical property evaluation result Dip Strength (g / d) Cutting Elongation (%) Adhesive force (kg) Intermediate Elongation (%) Dry heat shrinkage (%) Example 1 17.2 5.7 13.0 0.5 0 Example 2 15.1 6.2 14.2 0.7 0 Example 3 12.2 6.8 14.8 1.0 0 Example 4 16.1 5.0 15.8 0.4 0 Comparative Example 1 19.6 2.8 9.0 0.2 0 Comparative Example 2 14.9 2.9 14.5 0.3 0

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

3 is a process schematic diagram of making aramid filament fibers.

Claims (11)

An aramid tire cord comprising an aramid multifilament, having a dip strength of 10 to 23 g / d, an elongation at break of 3 to 10%, and a rubber adhesive force of at least 10 kg. The aramid tire cord according to claim 1, wherein the total fineness of the aramid tire cord is 800 to 10,000 denier. The aramid tire cord according to claim 1, wherein the aramid is poly (para-phenylene terephthalamide). The aramid tire cord according to 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 aramid tire cord according to claim 1, wherein the total fineness of the aramid multifilament is 400 to 5,000 denier. The aramid tire cord according to claim 1, wherein the aramid multifilament is composed of 500 to 1,200 aramid monofilaments. The aramid tire cord according to claim 6, wherein the single yarn fineness of the aramid monofilament is 1 to 2 denier. The aramid tire cord according to claim 1, wherein the median elongation of the aramid tire cord measured under a load of 6.75 kg is 0.3 to 1.5%. The aramid tire cord according to claim 1, wherein the dry heat shrinkage rate of the aramid tire cord is 0.3 to -1.0%. After giving the upper edge (Z lead) twist to the aramid multifilament having the following physical properties, and then twisting while giving the lower strand (S lead) twist to the two strands on the upper stage to prepare an aramid twisted yarn, then resorcinol-formaldehyde-latex (RFL) immersed in the solution so that the pick-up rate is 3 to 12% by weight based on the aramid twisted yarn, dried for 10 seconds to 400 seconds at 105 ~ 200 ℃, heat treatment for 10 seconds to 400 seconds at 105 ~ 300 ℃ Aramid tire cord manufacturing method comprising a. Physical Properties of Aramid Filaments -Strength: 10 ~ 25g / d -Elongation at break: 2 ~ 6% Modulus: 400 ~ 750g / d The method of manufacturing an aramid tire cord according to claim 10, characterized in that the number of twists of each of the upper (Z) and lower (S) strands is 20 to 60 times / 10 cm.

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