KR101476279B1 - Rubber composition for tire bead insulation and tire manufactured by using the same - Google Patents

Abstract

The present invention relates to a rubber composition for tire bead insulation and a tire produced using the same, wherein the rubber composition for tire bead insulation is a styrene-butadiene rubber composition prepared by hot polymerizing rosin acid with an emulsifier -Butadiene rubber as raw rubber.
The rubber composition for tire bead insulation can maintain hardness and strength while enhancing adhesion between rubber and bead wire.

Description

TECHNICAL FIELD [0001] The present invention relates to a rubber composition for tire bead insulation and a tire produced using the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to a rubber composition for tire bead insulation and a tire made using the same, and more particularly, to a rubber composition for tire bead insulation which can maintain hardness and strength while enhancing adhesion between rubber and bead wire, The present invention relates to a tire produced.

Generally, a bead of a tire refers to a portion of the tire closely attached to a rim of a vehicle. The bead is a very important part for preventing a tire attached to an automobile from falling off during traveling and maintaining air pressure inside the tire.

In order to firmly adhere to the rim in such a manner, the bead wire should be topped with insulating rubber and rolled up to a certain size so as to be manufactured as one ring.

In general, the bead portion of a tire is constituted by attaching a bead filler to the upper side of a bead core formed like a ring and turning up a carcass to the outside of the bead core and the bead filler, The rubber is wound after topping so that its outer shape is formed to have a square or hexagonal shape.

Since the bead core thus formed is subjected to stress concentration due to the weight of the vehicle body and the direction of the vehicle during the process of being mounted on the vehicle after the vulcanization and vulcanization, and the carcass tension is continuously transmitted, the tire between the bead wire and the bead wire The rubber for bead insulation breaks, and the bonding force of the bead wire is broken, so that the bead wires of the combined bead core portions are disturbed from each other, thereby deteriorating the bead durability remarkably.

Therefore, in the case of the rubber composition for tire bead insulation, high adhesion and high hardness of the bead wire and rubber are required to maintain the durability of the tire. For this purpose, a large amount of carbon black and sulfur are added to increase the reinforcing effect and the cross-linking density to obtain a hard rubber composition having a hardness of 90. This is because the rubber composition before vulcanization is very hard, Or the flow of the rubber composition during the bead wire topping operation deteriorates and the wire topography is difficult to achieve evenly over the entire bead wire, and the topping thickness of the rubber composition during topping is very thin. And the like.

In order to solve the above-mentioned problems, conventional arts have used a liquid polyisoprene rubber (Korean Patent Publication No. 1999-0015896) or a liquid natural rubber 2002-0003414), there is proposed a method of improving the processability, but the above measures have not improved the adhesion between the bead wire and the rubber, only improving the processability.

Korean Patent No. 1000813 (Registered on Dec. 7, 2010) Korean Patent Publication No. 1999-0015896 (published on March 30, 1999) Korea Patent Publication No. 2002-0003414 (published on January 12, 2002)

An object of the present invention is to provide a rubber composition for tire bead insulation which can maintain the hardness and strength while increasing the adhesive force between rubber and bead wire.

Another object of the present invention is to provide a tire produced using the rubber composition for tire bead insulation.

In order to achieve the above object, a rubber composition for tire bead insulation according to an embodiment of the present invention comprises a styrene-butadiene rubber prepared by hot polymerizing rosin acid with an emulsifier, .

The high-temperature polymerization may be carried out at 40 to 60 ° C.

The styrene-butadiene rubber may have a styrene content of 22.5 to 24.5% by weight, a weight average molecular weight (Mw) of 500,000 to 1,000,000 g / mol and a degree of dispersion (PDI, Mw / Mn) of 5 to 8.

The raw material rubber may include 20 to 80 parts by weight of the styrene-butadiene rubber and 20 to 80 parts by weight of the natural rubber.

The tire bead insulation rubber composition may further comprise 2 to 10 parts by weight of a vulcanization agent and 70 to 140 parts by weight of carbon black.

The tire bead insulation rubber composition may further include 0 to 30 parts by weight of an inorganic filler.

The tire according to another embodiment of the present invention is manufactured by using the rubber composition for tire bead insulation.

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

The rubber composition for tire bead insulation according to an embodiment of the present invention includes a styrene-butadiene rubber prepared by hot polymerizing rosin acid with an emulsifier.

The high-temperature polymerization may be carried out at 40 to 60 ° C. The styrene-butadiene rubber prepared by the above-mentioned high-temperature polymerization has many chain branches as compared with the styrene-butadiene rubber prepared by cold polymerization, and thus has excellent green strength.

In addition, styrene-butadiene rubber which is commonly used uses rosin acid and fatty acid together as an emulsifier. The styrene-butadiene rubber using the fatty acid as an emulsifier has a disadvantage that tacking performance is poor. On the other hand, the styrene-butadiene rubber has good green strength and good adhesion (adhesion, cohesion, tack) performance by using only rosin acid as an emulsifier at high temperature.

The styrene-butadiene rubber may have a styrene content of 22.5 to 24.5% by weight, a weight average molecular weight (Mw) of 500,000 to 1,000,000 g / mol and a degree of dispersion (PDI, Mw / Mn) of 5 to 8. The hot polymerized styrene-butadiene rubber has a relatively broad molecular weight distribution as compared to the conventionally used cold polymerized styrene-butadiene rubber. Specifically, the high temperature polymerized styrene-butadiene rubber has a weight average molecular weight of 500,000 to 1,000,000 g / mol and a degree of dispersion (PDI, Mw / Mn) of 5 to 8, A molecular weight of 500,000 to 800,000 g / mol, and a degree of dispersion of 3 to 5. The high-temperature-polymerized styrene-butadiene rubber has a relatively high molecular weight distribution, and thus has excellent tack performance.

The styrene-butadiene rubber having the above physical properties has excellent green strength and an appropriate level of adhesive performance. As it has pressure-sensitive adhesives, the rubber composition for tire bead insulation comprising the rubber and the bead wire The hardness and strength can be maintained while increasing the adhesive strength.

The raw material rubber may further include a natural rubber in addition to the styrene-butadiene rubber.

The natural rubber may be a general natural rubber or a modified natural rubber.

The above-mentioned general natural rubber may be used as long as it is known as natural rubber, and the country of origin and the like are not limited. The natural rubber includes cis-1,4-polyisoprene as a main component, but may also include trans-1,4-polyisoprene depending on required characteristics. Therefore, in addition to natural rubber containing cis-1,4-polyisoprene as a main component, natural rubber including trans-1,4-isoprene as a main component, such as balata, Rubber may also be included.

The modified natural rubber means that the general natural rubber is modified or purified. Examples of the modified natural rubber include epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), hydrogenated natural rubber and the like.

The natural rubber may preferably be used as a rubber composition for a tire rim cushion in which the foreign matter content is 0.2 wt% or less and the specific gravity is 0.90 to 0.99.

The raw rubber may include 20 to 80 parts by weight of the natural rubber and 20 to 80 parts by weight of the butadiene rubber. If the content of the natural rubber is less than 20 parts by weight, the butadiene rubber may relatively increase and the workability may be deteriorated. When the amount exceeds 80 parts by weight, the workability is favorable but the physical properties such as rebound resilience or heat generation may be deteriorated.

The rubber composition for tire bead insulation may further include various additives such as an additional vulcanizing agent, a vulcanization accelerator, a vulcanization accelerator, a filler, an anti-aging agent or a softening agent. Any of the various additives may be used as long as they are commonly used in the field to which the present invention belongs. The content thereof is not particularly limited as long as it is dependent on the compounding ratio used in a conventional rubber composition for tire bead insulation.

As the vulcanizing agent, a sulfur vulcanizing agent can be preferably used. The sulfur vulcanizing agent may be an inorganic vulcanizing agent such as powdered sulfur (S), insoluble sulfur (S), precipitated sulfur (S), or colloid sulfur. As the sulfur vulcanizing agent, a vulcanizing agent which produces elemental sulfur or sulfur, for example, amine disulfide, polymer sulfur and the like can be used.

It is preferable that the vulcanizing agent is included in an amount of 2 to 10 parts by weight based on 100 parts by weight of the raw material rubber, because it is a vulcanization effect and is less sensitive to heat and chemically stable.

The vulcanization accelerator refers to an accelerator that promotes the vulcanization rate or accelerates the retardation in the initial vulcanization step.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamate, aldehyde-amine, aldehyde-ammonia, imidazoline, Or a combination thereof.

The vulcanization accelerator may be included in an amount of 0.5 to 4.0 parts by weight based on 100 parts by weight of the raw material rubber in order to maximize productivity improvement and rubber property enhancement through vulcanization speed promotion.

The above-mentioned vulcanization accelerating assistant may be used together with zinc oxide and stearic acid as a compounding agent used in combination with the vulcanization accelerator to complete its promoting effect. In this case, the zinc oxide is dissolved in the stearic acid, To form an effective complex with the rubber to facilitate the crosslinking reaction of the rubber by producing favorable sulfur during the vulcanization reaction.

When the zinc oxide and the stearic acid are used together, they may be used in an amount of 1 to 5 parts by weight and 0.5 to 3 parts by weight, respectively, based on 100 parts by weight of the raw rubber to serve as a proper vulcanization accelerator. If the content of the zinc oxide and the stearic acid is less than the above range, the vulcanization rate may be slow and the productivity may be deteriorated. If the content exceeds the above range, the scorch phenomenon may occur and the physical properties may be deteriorated.

The filler may be any one selected from the group consisting of carbon black, calcium carbonate, clay (hydrated aluminum silicate), aluminum hydroxide, lignin, silicate, talc,

The carbon black may be included in an amount of 70 to 140 parts by weight based on 100 parts by weight of the raw rubber, and the inorganic filler may be included in an amount of 0 to 30 parts by weight. If the content of the carbon black is less than 70 parts by weight, the reinforcing performance of the carbon black as a filler may be deteriorated. If the content of the carbon black is more than 140 parts by weight, workability of the rubber composition may be deteriorated.

The softening agent is added to the rubber composition in order to impart plasticity to the rubber to facilitate processing or to decrease the hardness of the vulcanized rubber, and means an oil or other material used in rubber compounding or rubber production. The softening agent means an oil contained in a process oil or other rubber composition. The softener may be selected from the group consisting of petroleum oils, vegetable oils, and combinations thereof, but the present invention is not limited thereto.

Particularly, the oil used as the softening agent preferably has a total content of PAHs components of not more than 3 wt%, a kinematic viscosity of not less than 95 (210 S SUS), an aromatic component of 15 to 25 wt%, a naphthene component Of 27 to 37% by weight and a paraffinic component of 38 to 58% by weight can be preferably used.

The TDAE oil has favorable properties for environmental factors such as low temperature property and fuel efficiency of tire bead insulation including TDAE oil, and possibility of cancer induction of PAHs.

It is preferable that the softening agent is used in an amount of 0 to 150 parts by weight based on 100 parts by weight of the raw material rubber in order to improve workability of the raw material rubber.

The antioxidant is an additive used to stop the chain reaction in which the tire is autoxidized by oxygen. As the anti-aging agent, any one selected from the group consisting of an amine type, a phenol type, a quinoline type, an imidazole type, a carbamic acid metal salt, a wax and a combination thereof can be appropriately selected and used.

Considering the conditions that the solubility of the antioxidant in addition to the anti-aging action is high, the solubility in the rubber is small, the volatility is small, the solubility should be inactive to the rubber, and the vulcanization should not be inhibited, By weight.

The rubber composition for tire bead insulation can be produced through a conventional two-step continuous manufacturing process. That is, during the finishing step in which the first stage of thermomechanical treatment or kneading and the crosslinking system are mixed at a maximum temperature of 110 to 190 占 폚, preferably at a high temperature of 130 to 180 占 폚, typically less than 110 占 폚, And a second step of mechanical treatment at a low temperature of 40 to 100 DEG C in a suitable mixer, but the present invention is not limited thereto.

The rubber composition for tire bead insulation is not limited to bead insulation but may be included in various rubber components constituting the tire. Said rubber components include treads (tread caps and tread bases), sidewalls, sidewall inserts, apex, chafer, wire coat or inner liner.

A tire according to another embodiment of the present invention is manufactured using the rubber composition for tire bead insulation. A method of manufacturing a tire using the rubber composition for tire bead insulation may be any method conventionally used for manufacturing a tire, and a detailed description thereof will be omitted herein.

The tires may be automobile tires, racing tires, airplane tires, agricultural tires, off-the-road tires, truck tires or bus tires. Further, the tire may be a radial tire or a bias tire, and preferably a radial tire.

The rubber composition for tire bead insulation of the present invention can maintain the hardness and strength while increasing the adhesive force between the rubber and the bead wire.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

[ Manufacturing example : Preparation of rubber composition]

The composition as shown in Table 1 below was added to a Banbury mixer, and the rubber compositions of the comparative examples and the examples were compounded using a conventional compounding method, followed by vulcanization at 150 占 폚 for 30 minutes to prepare rubber specimens.

Item Comparative Example 1 Example 1 Example 2 Example 3 Natural rubber 50 50 - - Synthetic rubber A ⁽¹⁾ 50 - 100 - Synthetic rubber B ⁽²⁾ - 50 - 100 Carbon black 100 100 100 100 brimstone 6 6 6 6 Vulcanization accelerator 1.2 1.2 1.2 1.2

week)

(Unit: parts by weight)

(1) Synthetic rubber A: SBR1502

(2) Synthetic rubber B: ISP Elastomer company SBR1011AE product; bound styrene content of 22.5 to 24.5% by weight and prepared by hot polymerizing rosin acid with an emulsifier

[ Experimental Example : Measurement of physical properties of the prepared rubber composition]

The physical properties of the rubber specimens prepared in Examples and Comparative Examples were measured and the results are shown in Table 2 below.

Item Comparative Example 1 Example 1 Example 2 Example 3 Hardness 90 90 90 90 The tensile strength 100 99 99 98 Adhesion 100 150 150 200

Note) Adhesion is the bond strength between bead wire and bead insulation rubber.

Referring to Table 2, it can be seen that the adhesion between the bead wire and the bead insulation rubber can be improved when the styrene-butadiene rubber having excellent pressure-sensitive adhesive performance is used.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, Of the right.

Claims (7)

Only styrene-butadiene rubber prepared by hot polymerizing rosin acid as an emulsifier is contained as raw rubber,
The high-temperature polymerization is carried out at 40 to 60 ° C,
Wherein the styrene-butadiene rubber has a styrene content of 22.5 to 24.5% by weight, a weight average molecular weight (Mw) of 500,000 to 1,000,000 g / mol and a degree of dispersion (PDI, Mw / Mn) ≪ / RTI > delete delete delete The method according to claim 1,
Wherein the tire bead insulation rubber composition further comprises 2 to 10 parts by weight of a vulcanization agent and 70 to 140 parts by weight of carbon black. The method according to claim 1,
Wherein the tire bead insulation rubber composition further comprises 0 to 30 parts by weight of an inorganic filler. A tire produced by using the tire bead insulation rubber composition according to claim 1.