KR100432128B1 - Rubber Composition for Studless Tire Tread - Google Patents

Abstract

The present invention relates to a rubber composition for studless tire treads in winter, and more particularly to a rubber composition for studless tire treads having improved physical properties including cellulose fibers and polyethylene surface-treated with a silicone compound will be.

The rubber composition of the present invention improves snow ice, low rolling resistance, and other physical properties on ice / snow roads, and is useful for studless tire treads in place of expensive silica. Can be used.

Description

Rubber composition for studless tire tread {Rubber Composition for Studless Tire Tread}

The present invention relates to a tread rubber composition for winter studless tires, and more particularly, to braking performance on ice / snow roads by adding cellulose and polyethylene surface-treated with a silicone compound (hereinafter abbreviated as “Snow Ice”). The present invention relates to a rubber composition for studless tire tread with low rolling resistance (abbreviated as "LRR") and other physical properties.

In general, there are two main types of tires: four season / summer tires and winter snow tires.

Since the two types of tires described above use differently from each other, not only the pattern shape of the tire tread but also the rubber composition of the tread is significantly different.

Conventionally, winter tires have used stud tires developed to increase braking and driving power on ice roads.However, stud tires have been banned after 87 years due to spike pin noise, poor riding comfort, and dust pollution. Instead, the use of studless tires with excellent ride comfort and noise reduction performance on snowy and dry roads is rapidly increasing. However, studless tires are superior to snow tires on frozen roads, but compared to stud tires, there are cases where braking and physical properties are somewhat inferior.

Snow tires require excellent traction on ice / snow roads as the most important feature. The first way to meet these requirements is to increase the friction by adding additional foam rubber into the tread rubber to improve braking performance. The second method is to use a small amount of reinforcing agent such as incorporating fiber into the tread rubber in order to lower the hardness. The third method is to add a large amount of processed oil, such as using a polymer having excellent low-temperature properties with less curing of rubber at low temperature. That's how.

Among the above methods, in order to improve the braking performance on the ice / snow road surface of winter tires, a studless tire using foam rubber is used to increase the friction between the tread and the road surface. The foamed rubber is a product that forms about 7,000 air bubbles in the surface of the tire groove in 1cm ² to exert excellent braking and driving power when driving on ice roads and snow roads. It is adsorbed on the ice road to prevent slipping.

This studless tire uses a special compounded rubber that maintains softness, and aims to increase the frictional force to the edge portion by the foaming hole and to increase the adhesive frictional force by removing the water film by the edge. However, the studless tire by the foamed rubber composition has a property of increasing the ratio of foaming holes, that is, the foaming rate, in order to increase the frictional force, and the increase of the foaming rate may soften the entire tread and further increase the ratio. There is a disadvantage in reducing the movement performance and wear resistance in the snow.

On the other hand, as a method of incorporating a fiber into a tread rubber, the case where a tire tread is comprised using the powder processed product containing a cellulose substance as a rubber composition is mentioned. The cellulose powder contained in the rubber composition does not form a chemical bond with the rubber component and thus not only precipitates on the surface of the tread, but also falls off during driving, resulting in dropping holes. This dropping hole contributes to the increase of the adhesive friction force in the same manner as the above-mentioned foamed hole. In addition, since such cellulose powder exists as an additive in the rubber composition until it precipitates on the surface of the tread and falls off, unlike the case of the above-mentioned foamed rubber, it does not cause softening of the tread surface, and deterioration of durability in non-snow paper. Does not cause.

This method was also found to reduce the rotational resistance of the tire when the regenerated cellulose fiber was used in the carcass that acts as a pressure vessel of the tire (US Pat. No. 4,926,920).

However, the carbon black is hydrophobic and the cellulose is hydrophilic in the process of blending the tire rubber composition including the cellulose material and the carbon black having high reinforcement. There is a problem that the dropping hole is irregularly biased in any one portion, the characteristics can not be sufficiently exhibited.

In order to solve the above problems, a method of using a polymer having excellent low-temperature characteristics with low curing of rubber at low temperatures has recently been proposed, and this method has been applied to a rubber composition for LRR tires with improved ride comfort and fuel efficiency, mainly in passenger car tires. Silica is used as an alternative to carbon black.

This is a technology that improves adhesive friction by lowering modulus at low temperature by using a silane coupling agent in order to disperse the surface polarity of silica and to disperse the silica in non-polar rubber hydrocarbon well. It is known but has a disadvantage in that wear resistance is degraded at high loads.

Accordingly, the present inventors have completed the present invention by finding a rubber composition for a studless tire tread of a new concept that overcomes the disadvantages of the prior art while studying to overcome the above disadvantages.

The present invention has been made to solve the above problems and by the necessity of the above, an object of the present invention is to improve the Snow Ice and LRR performance on snowy or frozen roads, and excellent performance rubber for studless tire tread It is an object to provide a composition.

The present invention to achieve the above object

Provided is a rubber composition for winter studless tires having improved physical properties by applying surface-treated cellulose fibers and polyethylene, and more specifically, for tread rubber compositions for studless tires comprising cellulose fibers and polyethylene surface-treated with silicone compounds. .

Hereinafter, the present invention will be described in detail.

The present invention provides a rubber composition for studless tire tread comprising 5 to 25 parts by weight of cellulose fibers surface-treated to 100 parts by weight of diene-based natural rubber and 1 to 10 parts by weight of polyethylene polymer, the surface treatment of the cellulose Preference is given to using silicone compounds for the reaction. At this time, the silicone compound is used 0.5 to 30 parts by weight with respect to the weight of the cellulose fiber, preferably 1 to 10 parts by weight is appropriate. This is because if the amount of the silicone compound used is less than 0.5 parts by weight, the effect of blending is hardly achieved, and if it exceeds 30 parts by weight, the reinforcement resistance and the wear resistance decrease, and the cost increases.

Here, the raw material rubber mainly uses a diene-based natural rubber, and in the embodiment of the present invention, a yellow ribbed smoked sheet or technical standard rubber by an international standard sample is used. Moreover , it is preferable to use substances, such as vinyl tri (2-methoxyethoxy) silane , 3-methacryloxypropyl trimethoxysilane, and 3-aminopropyl triethoxysilane , as said silicone compound. Meanwhile, the composition of the present invention may further include one or more additives selected from among vulcanization accelerators, vulcanizing agents, anti-aging agents, reinforcing agents, silica, carbon black and natural rubber in addition to the composition.

Any of the additives can be used as long as it is used in a conventional tire tread composition. Specifically, nt-butyl-2-benzol sulfenamide as a vulcanization accelerator, sulfur, stearic acid and zinc oxide can be used as a vulcanizing agent, and n-1,3-dimethylbutyl n-phenyl p-phenylenediamine as an antioxidant for rubber. , Poly-2,2,4-trimethyl 1,2-dihydroquinoline or waxy hydrocarbon can be used.

In the present invention, when the cellulose fiber is introduced into the tread composition, the problem that cellulose is not dispersed well due to the difference in polarity between rubber and cellulose is solved, and a method for improving snow ice properties has been sought. The surface treatment of the cellulose fibers with a silicone-based compound improves the dispersibility by making the cellulose and the rubber have the same polarity, so that the cellulose fibers are uniformly distributed in the rubber, causing cellulose to precipitate on the surface of the tread during driving and dropping holes. By removing the water film existing between the tread surface and the road surface on the frozen road surface, the friction force can be increased to improve braking performance. By adding polyethylene, a thermoplastic resin, for the purpose of improving the physical properties of the surface-treated cellulose fibers and rubber, it is possible to obtain an effect of improving braking and LRR performance and improving mechanical properties.

The effect obtained by this invention is demonstrated by comparing the characteristic of the rubber composition manufactured by the following example and the comparative example. However, the examples are only to illustrate the invention and the present invention is not limited by the following examples.

Preparation Example 1 Preparation of Surface-treated Cellulose Fibers (1)

10 g of vinyl tri (2-methoxyethoxy) silane (trade name: A-172) in 1 kg of cellulose fiber, carbon tetrachloride (CCl)₄A) 500 ml of solvent After the addition, the mixture was mixed in a mixer at a constant temperature for 1 hour, and then dried to prepare a surface-treated cellulose fiber.

Preparation Example 2 Preparation of Surface-treated Cellulose Fibers (2)

To 1 kg of cellulose fiber, 100 g of vinyl tri (2-methoxyethoxy) silane (trade name: A-172) and 500 ml of carbon tetrachloride (CCl ₄ ) solvent were added, and the mixture was mixed in a mixer at a constant temperature for 1 hour. After that, a surface-treated cellulose fiber was prepared by drying.

Example 1-5

A rubber sheet was prepared by blending a compounding agent using a Banbury mixer as shown in Table 1 below. The rubber sheet was vulcanized in a vulcanization press at 150 ° C. for 30 minutes to prepare test specimens, and the physical properties such as modulus, abrasion resistance, and viscoelasticity were measured and shown in Table 2.

Comparative Examples 1 and 2

After the preparation of the rubber specimen in the same manner as in the above Example according to the composition of Table 1 by adding a surface-treated cellulose fiber or silica, the physical properties such as modulus, wear resistance and viscoelasticity were measured and shown in Table 2.

The hardness of the rubber specimens prepared in Examples 1 to 5 and the rubber specimens prepared in Comparative Example were measured after 1 hour in a temperature-controlled combustion chamber by the ASTM shore-A hardness tester method; 300% modulus uses a 100mm long, 25mm wide and 5mm inner dumbbell, and from the beginning of the curve of the strain-stress when the specimen is stretched by 20mm long and 5mm wide. The method of stress on percent elongation was used; The elongation at break was used as a method of expressing the strain value in percent until the test piece was broken in the tensile tester. Tensile strength was also used the method of ASTM D 790; Abrasion resistance was measured by estimating the loss of worn rubber by rotating it at a skid ratio of 50 ° and a load of 1.5Kg at room temperature. The higher the index, the greater the index. In addition, Tan δ is measured using Rheo Dynamic Spectroscopy (RDS), which is expressed as Tan δ = (G ″ / G ′). Where G 'is measured as Viscous and G "as Elastic modulus value.

TABLE 1

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Diene Natural Rubber (1) 100 100 100 100 100 100 100 Polyethylene (2) 2 2 4 4 6 - - Carbon Black (3) 40 40 40 40 40 45 0 Silica (4) 0 0 0 0 0 0 45 cellulose 0 0 0 0 0 10 0 Surface Treatment Cellulose (5) 5 10 15 0 0 0 0 Surface TreatmentCellulose (6) 0 0 0 15 20 0 0 zinc oxide 4 4 4 4 4 4 4 Stearic acid 3 3 3 3 3 3 3 Antioxidant (7) 1.5 1.5 1.5 1.5 1.5 1.5 1.5 Antioxidant (8) One One One One One One One Antioxidant (9) One One One One One One One Vulcanization accelerator One One One One One One One Sulfur 1.7 1.7 1.7 1.7 1.7 1.7 1.7 (1) Dark brown to yellow ribbed smoke sheet using diene-based natural rubber (2) Polyethylene: LLDPE (Linear Low Density Polyethylene) (3) N2 SA value is 95-150 m ² / g and DBP oil absorption Carbon black (4) N2 SA with 90 to 130 ml / 100g N2 SA Cellulose fibers surface-treated with 1 part by weight of a silicone compound with respect to silica (5) cellulose fibers having a SAB value of 175 m ² / g and a CTAB surface area of 166 m ² / g (Manufacture example 1) (6) Cellulose fiber which surface-treated with 10 weight part of silicone compounds with respect to a cellulose fiber (Manufacture example 2) (7) n-1,3-dimethylbutyl n-phenyl p-phenylenediamine (8) poly -2,2,4-trimethyl 1,2-dihydroquinoline (9) waxy hydrocarbon

The results obtained in Examples and Comparative Examples described above are shown in Table 2 below.

TABLE 2

Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Tensile Properties Hardness 65 65 67 68 69 69 70 300% modulus 169 175 171 176 189 171 165 Elongation at Break (%) 425 428 431 434 443 402 389 Tensile Strength (Kg / cm2) 236 228 235 241 249 224 219 Wear Resistance (Lambourn Wear) 100 98 95 97 95 92 90 Tanδ -20 ℃ 0.268 0.274 0.276 0.280 0.290 0.249 0.268 60 ℃ 0.123 0.125 0.121 0.119 0.117 0.129 0.124

As shown in Table 2, when comparing the Examples and Comparative Examples, the viscoelasticity at the time of introduction of the composition of the surface-treated cellulose increases as the amount of the surface-treated cellulose increases in the case of Tanδ (-20 ° C) and Tanδ (60 ° C). In the case of), the amount of cellulose treated with the surface decreases and the snow ice and LRR properties increase when the surface treated cellulose is included.

In Examples 3 and 4, when the silicon compound was surface-treated with 10 parts by weight of cellulose fibers, Tanδ (-20 ° C.) was increased compared to that with 1 part by weight, showing an excellent effect on snow ice properties. Able to know.

In addition, when compared with Example 2 and Example 4, it can be seen that when the polyethylene polymer is added, the elongation and tensile strength at break increase, and even when the wear resistances of Examples 1 to 3 and 4 to 5 are compared, It can be seen that even though the amount of cellulose treated increases, the difference in physical properties is not large.

On the other hand, in the case of Comparative Example 1 to which the cellulose which is not surface treated is added, it shows that the physical properties are poor in abrasion resistance and the dispersibility of cellulose is inferior.

As described above, the present invention relates to a rubber composition of a studless tire comprising a surface-treated cellulose fiber and polyethylene, and using the rubber composition of the present invention not only improves wear resistance and snow ice resistance, but also LRR resistance. Provides improved, superior studless tires.

Claims (5)

Diene-based natural raw rubber; 5 to 25 parts by weight of cellulose fibers surface treated with a silicone compound and 1 to 10 parts by weight of polyethylene polymer based on 100 parts by weight of the raw material rubber; A rubber composition for a studless tire tread, comprising at least one additive selected from the group consisting of vulcanization accelerators, vulcanizing agents, anti-aging agents, reinforcing agents and silica. delete The method of claim 1, Said silicone compound is surface-treated using 0.5-30 weight part with respect to the weight of a cellulose fiber, The rubber composition for studless tire treads characterized by the above-mentioned. The method of claim 3, wherein Said silicone compound is surface-treated using 1-10 weight part with respect to the weight of a cellulose fiber, The rubber composition for studless tire treads characterized by the above-mentioned. The method of claim 1, The silicone compound is vinyl tri (2-methoxyethoxy) silane, 3-methacryloxypropyltrimethoxysilane and 3-aminopropyltriethoxysilane Rubber composition for studless tire tread, characterized in that selected from.