KR20110071605A - Rubber composition for bead filler of tire, rubber for bead filler of tire manufactured by using the same - Google Patents

Abstract

PURPOSE: A rubber composition for tire bead filler and rubber for tire bead filler manufactured by the same are provided to facilitate molding by improving unvulcanized rigidity and stickiness and to ensure excellent processability, stickiness and properties. CONSTITUTION: A rubber composition for tire bead filler includes 100 parts by weight of a base rubber, 50 - 80 parts by weight of carbon black and 2 - 5 parts by weight of tert-butyl-phenol-based adhesive. The carbon black comprises: first carbon black in which dibutylphthalate(DBP) oil absorption is 75 - 105ml/100g and nitrogen adsorption specific area is 20 - 50m^2/g; and second carbon black in which dibutylphthalate oil absorption is 85 - 115ml/100g and nitrogen adsorption specific area is 70 - 90m^2/g.

Description

RUBBER COMPOSITION FOR BEAD FILLER OF TIRE, RUBBER FOR BEAD FILLER OF TIRE MANUFACTURED BY USING THE SAME

The present invention relates to a rubber composition for a tire bead filler and a rubber for a tire bead filler manufactured using the same, wherein the rubber composition for a tire bead filler having an excellent unvulcanized stiffness and adhesiveness at a low price and a tire bead prepared using the same It relates to rubber for filler.

The tire bead filler is disposed between the carcass turn-up portion surrounding the tire bead and the inner carcass to absorb the strain energy of the sidewall portion and improve the overall rigidity of the bead portion.

The tire bead filler has a bead filler base, which is a bottom surface of the triangle, attached to the bead while the entire cross-sectional shape is triangular. The bead filler is generally prepared by extruding rubber in the form of a bead filler and then attaching it to a round bead.

In the bead filler having the shape, a large tensile force is generated at the edge portion disposed at a position having a larger inner diameter than a base portion disposed at a position having a relatively small inner diameter, and the edge portion of the bead filler has a bead filler base. The so-called "rock phenomenon" occurs, in which the bead filler edge portion is bent in either side with respect to the height of the bead filler because the thickness is thin compared to the portion.

The gourd phenomenon tends to be worse as the gauge of the bead filler is smaller, and as the weight of the bead filler is made for the production of low fuel consumption and eco-friendly tire, the gauge of the bead filler is also smaller. Therefore, there is a need for a bead filler having a green stiffness equal to or higher than that of conventional rubber.

The prior art in terms of equipment to improve the gourd phenomenon is disclosed in the method of partially modifying the bead extruder and molding machine in the Republic of Korea Patent Publication No. 2002-39871, to improve the gourd phenomenon by improving the rubber composition Korean technology has been presented in Korean Patent Publication Nos. 1999-0025415 and 2003-0080453.

However, when the cashew modified phenol resin and the methylene donor type vulcanizing agent are used at the same time, it is possible to improve the gourd phenomenon due to the high unvulcanized stiffness, but the hardness is excessively high, which makes it impossible to use the soft bead filler. Soft bead fillers that do not use cashew modified phenolic resins have a disadvantage that the gauge cannot be manufactured because the stiffness of the unvulcanized rubber is reduced and the ripple occurs.

In addition, the liquid isoprene used in the rubber composition for the tire bead filler of the prior art is expensive as a proprietary raw material, an effort to obtain the desired physical properties while lowering the price to replace it continues.

An object of the present invention is to replace the expensive proprietary raw material to improve the uncured stiffness and adhesiveness of the low-cost, easy molding, and does not occur the ripple phenomenon, the rubber composition for the tire bead filler having excellent field processability, adhesiveness and physical properties To provide.

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

In order to achieve the above object, the rubber composition for the tire bead filler according to an embodiment of the present invention is 100 parts by weight of the raw material rubber, 50 to 80 parts by weight of carbon black, and tert-butyl-phenol-based It contains 2 to 5 parts by weight of the adhesive.

The carbon black has a dibutyl phthalate (DBP) oil absorption of 75 to 105ml / 100g and a nitrogen adsorption specific surface area of 20 to 50m 2 / g of first carbon black and dibutylphthalate oil absorption of 85 to 115ml / 100g and nitrogen adsorption. Second carbon black having a specific surface area of from 70 to 90 m 2 / g.

The raw rubber may include 50 to 80 parts by weight of natural rubber, and 20 to 50 parts by weight of styrene butadiene rubber.

The rubber bead filler rubber composition may include 5 to 20 parts by weight of cashew modified phenol resin and 1 to 5 parts by weight of hexamethylenetetraamine.

The rubber bead filler rubber composition may comprise 1 to 5 parts by weight of insoluble sulfur.

The first carbon black and the second carbon black may be included in a weight ratio of 30:50 to 60:20.

Rubber for tire bead filler according to another embodiment of the present invention is prepared using the rubber bead filler rubber composition.

The hardness (Shore A) of the tire bead filler rubber may be 75 to 95.

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

The rubber bead filler rubber composition includes a raw material rubber, carbon black, and a tert-butyl-phenol-based pressure-sensitive adhesive.

Since the rubber composition for the tire bead filler does not include liquid isoprene (LIR), which is a proprietary raw material that has been added to the raw material rubber to improve the adhesive force during the molding of the green tire, the price is low, but LIR is added. The same on-site workability, adhesiveness, and physical properties as those of the rubber bead filler rubber composition produced by the present invention are shown.

The raw rubber may be any one selected from the group consisting of natural rubber, synthetic rubber, and combinations thereof.

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

The general natural rubber may be used as long as it is known as a natural rubber, the country of origin and the like are not limited. The natural rubber contains cis-1,4-polyisoprene as the main, but may also comprise trans-1,4-polyisoprene depending on the required properties.

The synthetic rubber may be any one selected from the group consisting of styrene butadiene rubber (SBR), modified styrene butadiene rubber, and combinations thereof.

In particular, as the raw material rubber, it is preferable to use 50 to 80 parts by weight of natural rubber having a foreign matter content of 0.2 wt% or less, specific gravity of 0.90 to 0.99 and 20 to 50 parts by weight of styrene butadiene rubber having a specific gravity of 0.88 to 0.98. The content of the natural rubber is increased by the amount of liquid isoprene added to the conventional rubber bead filler rubber composition.

The carbon black, which is used as a reinforcing filler, has a dibutyl phthalate (DBP) oil absorption of 75 to 105 ml / 100 g, and a nitrogen adsorption specific surface area (N ₂ SA) of 20. The first carbon black having a content of from 50 m 2 / g and the second carbon black having a dibutyl phthalate oil absorption of 85 to 115 ml / 100 g and a nitrogen adsorption specific surface area of 70 to 90 m 2 / g are used simultaneously.

When the first carbon black and the second carbon black are used at the same time, the cashew modified phenol resin when the rubber bead filler rubber composition is prepared by replacing the liquid isoprene with a natural rubber having the same content and increasing the pressure-sensitive adhesive It is possible to use it as a soft bead filler because the vulcanization stiffness is not lowered even if it is not used, and even when using cashew modified phenol resin and hexamethylenetetramine, the hardness is not excessively high. You can make it available as a filler.

The first carbon black and the second carbon black may be included in a weight ratio of 30:50 to 60:20. In the case where the weight ratio of the first carbon black and the second carbon black is within the above range, it is preferable at the point that the desired tensile properties can be obtained and good moldability without the occurrence of ripple is obtained. There may be a problem that does not satisfy the tensile properties such as low or hardness.

The pressure-sensitive adhesive is used to secure the adhesive performance, the content is used in 2 to 5 parts by weight, preferably 3 to 5 parts by weight based on 100 parts by weight of the raw material rubber. Compared with the content of the pressure-sensitive adhesive used in the conventional rubber bead filler rubber composition is 1 to 3 parts by weight, the content of the pressure-sensitive adhesive increases while replacing the liquid isoprene with natural rubber in the rubber composition for tire bead filler of the present invention.

When the content of the pressure-sensitive adhesive is less than 2 parts by weight, the adhesive force of the rubber bead filler rubber composition is lowered, the adhesion with the adjacent rubber during molding may worsen, forming problems such as air is filled, if the amount exceeds 5 parts by weight As the pressure-sensitive adhesive acts as a plasticizer, the unvulcanized stiffness of the rubber composition for tire bead filler may be reduced, thereby causing a ripple phenomenon.

The pressure-sensitive adhesive may be a tert-butyl-phenol pressure-sensitive adhesive having a softening point of 125 to 139 ℃, specific gravity between 0.95 and 1.25, the tert-butyl-phenolic pressure-sensitive adhesive as a tert- Butyl-phenol condensed acetylene (p-tert-butyl-phenol condensated acetylene) may be used, and commercially available Koresin (Koresin) pressure-sensitive adhesive (manufactured by Structol).

The rubber bead filler rubber composition may further comprise 5 to 20 parts by weight of cashew modified phenol resin and 1 to 5 parts by weight of hexamethylenetetraamine.

The cashew modified phenolic resin is for improving the strength of the rubber, and when the cashew modified phenolic resin is not included, uncured stiffness may be lowered. The cashew-modified phenol resin may be a phenolic resin in the form of a novolak modified with cashew nut (cashew nut) oil, and commercially available SP6700 (manufactured by Schenectady Chemicals Inc.).

In addition, the cashew modified phenol resin may have a modification ratio of cashew oil based on the total phenol resin 10 to 50%. The cashew modified phenol resin may be prepared by various methods, for example, using an acid catalyst and reacting phenol, cresol, or resorcinol phenol with an aldehyde such as formaldehyde, paraformaldehyde or benzaldehyde, and then cashew. It can also be prepared by reforming with oil. Oxalic acid, hydrochloric acid, sulfuric acid and p-toluene sulfonic acid may be used as the acid catalyst.

When the content of the cashew-modified phenolic resin is less than 5 parts by weight based on 100 parts by weight of the raw material rubber, there may be a problem that the hardness and modulus are lowered. When the content of the cashew modified phenol resin exceeds 20 parts by weight, the elongation until breakage of the rubber is sharply reduced. There may be a problem that the hardness is higher than necessary.

When adding a cashew modified phenolic resin to improve the hardness of the rubber may cause a problem that the strength of the rubber for the tire bead filler at a high temperature drops sharply, it is preferable to add hexamethylenetetramine to compensate for this. If the content of hexamethylenetetramine is less than 1 part by weight with respect to 100 parts by weight of the raw rubber, it is not possible to prevent the problem of the strength of the tire bead filler rubber from dropping rapidly at a high temperature. The problem of shortening of time may occur.

When the cashew modified phenol resin and hexamethylene tetraamine are mixed with the raw material rubber, it is preferably carried out at a temperature of 150 to 190 ℃. When the mixing temperature is less than 150 ℃ hexamethylenetetraamine reacts with the cashew-modified phenolic resin is so weak that the hardness of the rubber after vulcanization can not be used as a soft bead filler, if it exceeds 190 ℃ mixed Deterioration of the physical properties of the raw rubber may occur to reduce the elongation to break.

The rubber bead filler rubber composition may optionally further include various additives such as vulcanizing agents, vulcanization accelerators, vulcanization accelerators, anti-aging agents, softeners. Any of the various additives can be used as long as they are commonly used in the field of the present invention.

As the vulcanizing agent, only insoluble sulfur may be used, and when the vulcanizing agent is included in an amount of 1 to 5 parts by weight based on 100 parts by weight of the raw material rubber, the vulcanizing agent shows a suitable vulcanizing effect, making the raw material rubber less sensitive to heat and chemically stable. Is preferred.

The vulcanization accelerator means an accelerator which accelerates the vulcanization rate or promotes delay in the initial vulcanization step, and may further include an additional vulcanization accelerator other than the hexamethylenetetramine.

Examples of the vulcanization accelerator include sulfenamide, thiazole, thiuram, thiourea, guanidine, dithiocarbamic acid, aldehyde-amine, aldehyde-ammonia, imidazoline, xanthate and their Any one selected from the group consisting of a combination can be used.

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 and rubber properties by promoting the vulcanization rate.

As the vulcanization accelerator, for example, any one selected from the group consisting of zinc oxide, zinc stearate, and combinations thereof can be used.

The softener is added to the rubber composition to impart plasticity to the rubber to facilitate processing or to lower the hardness of the vulcanized rubber. The softener may be any one selected from the group consisting of process oil, vegetable oil, and combinations thereof, but the present invention is not limited thereto.

The anti-aging agent is an additive used to stop the chain reaction in which the tire is automatically oxidized by oxygen. As the anti-aging agent, any one selected from the group consisting of amines, phenols, imidazoles, carbamic acid metal salts, and combinations thereof may be appropriately selected and used.

The anti-aging agent may be N- (1,3-dimethylbutyl) -N-phenyl-p-phenylenediamine (N- (1,3-Dimethybutyl) -N-phenyl-p-phenylenediamine, 6PPD), N-phenyl n-isopropyl-p-phenylenediamine (3PPD) and poly (2,2,4-trimethyl-1,2-dihydroquinoline (Poly (2,2) , 4-trimethyl-1,2-dihydroquinoline, RD) and a combination thereof can be preferably used.

Rubber for tire bead filler according to another embodiment of the present invention is manufactured using the rubber composition for the tire bead filler. Since the method for producing a tire bead filler rubber using the tire bead filler rubber composition can be applied to any method conventionally used for rubber production, a detailed description thereof will be omitted.

The tire bead filler rubber may have a hardness of 75 to 95 measured by a Shore A type hardness tester. When the hardness of the tire bead filler rubber is within the above range, the handling performance may be improved and durability may be satisfied, and when the hardness of the tire bead filler rubber is less than 75, there may be a problem in that the handling is lowered. If it exceeds 95, the moldability is lowered, there may be a problem that the durability of the tire is lowered.

The rubber composition for the tire bead filler of the present invention is easy to mold by replacing the expensive proprietary raw materials and improving the unvulcanized stiffness and tackiness, and has excellent field processability, tackiness and physical properties since the gourd phenomenon does not occur.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily practice 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.

[Production Example: Production of Rubber for Tire Bead Filler]

(Comparative Examples 1 to 5 and Examples 1 to 3)

The rubber for tire bead filler was manufactured using the rubber composition for tire bead filler having a composition as shown in Table 1 below. The tire bead filler rubber has been manufactured by a method generally used in the prior art, and thus detailed description thereof will be omitted.

In Examples 1 to 3, the rubber composition for tire bead filler was prepared by replacing all liquid isoprene rubber with natural rubber and increasing the pressure-sensitive adhesive.

Comparative Examples 1 and 2 were prepared by replacing all the liquid isoprene rubber with natural rubber and increasing the pressure-sensitive adhesive as in Examples 1 to 3, using only one type of carbon black to prepare a rubber bead filler rubber composition.

Comparative Example 3 is an example of a bead filler rubber composition generally applied to tires, a rubber composition for a tire bead filler was prepared by mixing 5 parts by weight of liquid isoprene.

In Comparative Example 4, all of the liquid isoprene rubber was replaced with natural rubber as in Examples 1 to 3, but the rubber composition for the tire bead filler was prepared by a method of not increasing the pressure-sensitive adhesive.

Comparative Example 5 was prepared by replacing all the liquid isoprene rubber with natural rubber and increasing the pressure-sensitive adhesive as in Examples 1 to 3, by changing the content of the pressure-sensitive adhesive to 7 parts by weight to prepare a rubber composition for the tire bead filler.

[Table 1] (Unit: parts by weight)

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example
One Example 2 Example 3 Comparative Example 5 Natural Rubber ⁽¹⁾ /
Styrene-butadiene rubber ⁽²⁾
Liquid isoprene 65/35 /- 65/35 /- 60/35/5 65/35 /- 65/35 /- 65/35 /- 65/35 /- 65/35 /- Carbon black (HAF ⁽³⁾ / GPF ⁽⁴⁾ ) 80 /- -/ 80 30/50 30/50 30/50 30/50 30/50 30/50 Zinc Oxide / Stearic Acid 12/3 12/3 12/3 12/3 12/3 12/3 12/3 12/3 Adhesive ⁽⁵⁾ 1.0 1.0 1.0 1.0 2.0 3.0 5.0 7.0 Cashew Modified Phenolic Resin ⁽⁶⁾ 10 10 10 10 10 10 10 10 Hexamethylenetetraamine 2.0 2.0 2.0 2.0 2.0 2.0 2.0 2.0 Accelerators ⁽⁷⁾ 1.5 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Insoluble sulfur 3.0 3.0 3.0 3.0 3.0 3.0 3.0 3.0

(1) Natural rubber: Natural isoprene rubber having a foreign matter content of 0.16% by weight and a specific gravity of 0.93.

(2) Styrene butadiene rubber: Styrene butadiene rubber with a Mooney viscosity of 52 and a specific gravity of 0.94

(3) Carbon black HAF: DBP oil absorption amount is 85-115 ml / 100g, nitrogen adsorption specific surface area is 70-90 m <2> / g

(4) Carbon Black GPF: DBP oil absorption is 75 to 105ml / 100g, nitrogen adsorption specific surface area is 20 to 50m 2 / g

(5) Pressure-sensitive adhesive: p-tert-butyl-phenol acetylene condensation resin having a softening point of 130 ° C. and specific gravity of 1.0

(6) cashew modified phenolic resin: cashew modified phenolic resin having a softening point of 95 ° C. and a specific gravity of 1.1.

(7) Vulcanization accelerator: N-tert-butyl-2-benzothiazylsulfenamide (TBBS)

Experimental Example: Measurement of Physical Properties of Manufactured Tire Bead Filler Rubber

Processability, tensile properties, adhesive force and unvulcanized stiffness were measured using the rubber for tire bead fillers prepared in Comparative Examples 1 to 5 and Examples 1 to 3, and whether or not occurrence of gourd phenomenon occurred in the rubber manufacturing process for bead filler. Observations are shown in Table 2 below.

In Table 2, the occurrence of gourd phenomenon was measured by winding the extruded tire bead filler rubber on a 14 inch bead.

Adhesion was measured six times using a track tester, and then the average adhesion was calculated and described.

The band stiffness was indexed based on the comparative example 1 with the value measured in the 3-point band stiffness test with the unvulcanized rubber sample. The larger the band stiffness, the better the unvulcanized stiffness.

Scorch time was measured with a patterned bismeter. The scorch time is a measure of the time it takes to increase 5 points from the pattern minimum, indicating that the scorch stability is improved as the time is longer.

Hardness is the value measured with the Shore A type durometer.

Modulus was measured by a tensile tester (Instron Co., Ltd.) by cutting the specimen into dumbbell-shaped, 100% modulus refers to the stress acting on the specimen when the specimen is stretched 100%.

TABLE 2

Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Example 3 Comparative Example 5 Machinability Mooney Viscosity (ML1 + 4) 65 61 63 64 62 60 58 56 Scorching time (t5, min) 10.4 11.2 11.0 10.8 10.8 10.9 10.2 9.6 Tensile Properties Shore A 95 92 93 93 93 93 93 92 100% modulus
(kgf / cm ² ) 80 69 75 78 77 76 74 70 % Elongation 265 270 260 265 268 271 275 285 Tensile strength (kgf / cm ² ) 163 166 161 162 163 165 162 156 adhesiveness Tack test (kgf) 1.50 1.55 1.65 1.51 1.56 1.68 1.72 1.76 Unvulcanized Rigidity 3-point band stiffness test 102 101 100 106 104 103 99 94 Ripple phenomenon 48hrs after attaching to Bead none none none none none none Occur Occur

Referring to Table 2, Examples 1 to 3 exhibited the same tensile properties as Comparative Example 3 by using 2 to 5 parts by weight of tert-butyl-phenolic adhesive while replacing liquid isoprene with natural rubber. It can be seen that no performance of any of the unvulcanized stiffness (band stiffness) has been sacrificed.

Comparative Examples 1 and 2 are prepared by replacing all of the liquid isoprene rubber with natural rubber and increasing the pressure-sensitive adhesive as in Examples 1 to 3, it can be seen that the adhesive force is rapidly reduced by using only one type of carbon black.

In addition, in the case of Comparative Example 4 it can be seen that the adhesive force is sharply reduced by including 1.0 parts by weight of the adhesive without containing liquid isoprene as compared to Comparative Example 3. Therefore, in actual tire molding, there is a high possibility of a problem of adhesion between the rubber for the tire bead filler and the adjacent rubber.

In the case of Comparative Example 5, as the pressure-sensitive adhesive is increased to 7.0 parts by weight, the adhesive strength increases, but as the content of the tert-butyl-phenolic pressure-sensitive adhesive that acts as a plasticizer increases, the unvulcanized stiffness (3-point band stiffness) decreases significantly. The result is that the gourd phenomenon occurs.

Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

Claims (7)

100 parts by weight of raw rubber, 50 to 80 parts by weight of carbon black, and 2 to 5 parts by weight of tert-butyl-phenol-based adhesive Including; The carbon black has a dibutyl phthalate (DBP) oil absorption of 75 to 105ml / 100g and a nitrogen adsorption specific surface area of 20 to 50m 2 / g of first carbon black and dibutylphthalate oil absorption of 85 to 115ml / 100g and nitrogen adsorption. It comprises a second carbon black having a specific surface area of 70 to 90 m 2 / g Rubber composition for tire bead filler. The method of claim 1, The raw material rubber 50 to 80 parts by weight of natural rubber, and 20-50 parts by weight of styrene butadiene rubber A rubber composition for a tire bead filler comprising a. The method of claim 1, The rubber bead filler rubber composition 5 to 20 parts by weight of cashew modified phenolic resin and 1 to 5 parts by weight of hexamethylenetetraamine A rubber composition for a tire bead filler comprising a. The method of claim 1, The rubber bead filler rubber composition A rubber composition for a tire bead filler comprising 1 to 5 parts by weight of insoluble sulfur. The method of claim 1, The first carbon black and the second carbon black is a rubber composition for the tire bead filler is included in a weight ratio of 30: 50 to 60: 20. A rubber for tire bead filler manufactured by using the rubber composition for tire bead filler according to any one of claims 1 to 5. The method of claim 6, The hardness of the tire bead filler rubber (Shore A) is a rubber for tire bead filler is from 75 to 95.