KR20230027573A - Tread rubber composition for tires - Google Patents

Abstract

The present invention relates to a tread rubber composition for tires. The present invention can provide a tread rubber composition for tires having improved braking power on a wet road surface while maintaining braking power on a snowy road in a hot region or winter. The tread includes low-temperature SBR and hydrocarbon resins to improve braking and wear on wet roads/snowy roads and further includes a specific vulcanizer to supplement abrasion and rolling resistance performance.

Description

Tread rubber composition for tires {Tread rubber composition for tires}

The present invention relates to a rubber composition for tires with improved braking and abrasion performance, and more particularly, by applying a mixture of raw rubber with a low glass transition temperature and a resin with a high glass transition temperature, braking on wet roads and snowy roads is improved. It relates to a tread rubber composition for tires with improved wear performance as well.

As for tires, it is necessary to secure technology that takes not only braking performance for consumer safety, but also abrasion performance in consideration of electric vehicle tires with high weight and high horsepower characteristics. In addition, since performance on wet roads is important, it is required to maintain it at a constant level, and to overcome the trade-off of each performance, for example, wet road braking performance is proportional to glass transition temperature (Tg) and snow braking performance Since the abrasion performance is the opposite, a new concept of compound technology is required to overcome this. That is, a technology for simultaneously improving the braking performance of a snow road surface (snow road) and a wet road surface is required.

For example, instead of the terpene resin used in Prior Patent No. 10-2019-0118177, in the present invention, a hydrogenated hydrocarbon resin (H2 / DCPD / ( When C9)) is applied, wet and snow braking and abrasion performance are simultaneously improved, and fuel efficiency is greatly improved. This has advantages over terpene resins with relatively high hysteresis in terms of performance. More specifically, it has a low Tg, so the snow performance index is improved, and the overall characteristics of adhesion and hysteresis can be more balanced, so it can be used on wet roads. It also has strengths in braking performance, low fuel consumption performance due to relatively low hysteresis, and improved tearing and slip wear aspects. Overall, it has balanced performance.

In addition, Patent Publication No. 10-2019-0060053 discloses 100 parts by weight of raw rubber made of only natural rubber, 30 to 55 parts by weight of carbon black, and 5 to 25 parts by weight of silica; and 2 to 15 parts by weight of a dehydrogenated C9-dicyclopentadiene (C9-DCPD) resin. Instead of cyclopentadiene (C9-DCPD), hydrogenated C9-dicyclopentadiene (H2/DCPD/(C9)) raw material rubber content, filler content, and H2/DCPD/(C9) resin were applied to hydrogenation. As the double bond is broken, the miscibility with rubber is increased, and there is a technical difference from this patent in the part where wear / RR performance is improved accordingly.

In addition, Patent Publication No. 10-2016-0069393 is a rubber composition for tires, which is introduced to improve wet and fuel efficiency. The hydrogenated H2 / DCPD resin of the first adhesive resin and the resin H2 / DCPD / (C9) mentioned in this patent are different in type, and the amount of resin is also different, and when used in a small amount as in the above patent, wet road surface and fuel economy performance The improvement level of is different from this patent.

Publication No. 10-2019-0118177 Publication No. 10-2019-0060053 Publication No. 10-2016-0069393

The present invention is to solve the problems of the prior art as described above, and an object of the present invention is a tire tread having a technology that further improves snow braking and wet road braking performance and abrasion performance than the prior art, and also improves low fuel consumption performance. It is to provide a rubber composition for use.

In order to achieve the above object, the present invention provides a tire tread rubber composition comprising a raw material rubber and a hydrocarbon-based resin.

In addition, the present invention provides a tire comprising the above rubber composition.

In the tire rubber composition of the present invention, the raw material rubber may be natural rubber (NR), synthetic rubber, or a mixture thereof.

In the tire tread rubber composition of the present invention, the type of synthetic rubber is not particularly limited, and examples thereof include styrene butadiene rubber, butadiene rubber, butyl rubber, emulsion polymerization styrene butadiene rubber (E-SBR), solution polymerized styrene butadiene rubber (S-SBR), epichlorohydrin rubber, nitrile rubber, hydrogenated nitrile rubber, brominated polyisobutyl isoprene-co-paramethyl styrene (BIMS) rubber, urethane rubber, fluororubber, silicone rubber, styrene ethylene butadiene styrene copolymer rubber, ethylene propylene rubber, ethylene propylene diene monomer rubber, hypalon rubber, chloroprene rubber, ethylene vinyl acetate rubber, and acrylic rubber.

In the tire tread rubber composition of the present invention, the raw material rubber is styrene butadiene rubber containing 10 to 20% by weight of styrene and 1 to 30% by weight of vinyl, 40 to 90 parts by weight, preferably 50 to 90 parts by weight of the total weight of raw rubber 80 parts by weight may be included, and at least one of butadiene rubber or natural rubber may be included in 10 to 60 parts by weight, preferably 20 to 50 parts by weight, based on the total weight of raw rubber, but is not limited thereto. When the raw rubber is included below the above range, the wet braking index is improved, but the actual braking performance is not improved, and when it is included above the above range, abrasion / rolling resistance (RR) / snow road Excessive braking performance, blending processability, and adhesiveness may cause problems in molding processability.

In addition, the glass transition temperature of the styrene butadiene rubber may be -70 to -40 ℃. If it is out of the glass transition temperature, wet road braking performance may decrease if it is less than the above range, and snow braking performance may decrease if it exceeds the above range.

The hydrocarbon-based resin is not limited, but may preferably have a structure of hydrogenated DCPD (Dicyclopentadiene)/(C9), that is, (H2/DCPD (Dicyclopentadiene)/(C9)). The hydrocarbon-based resin is not limited, but may preferably have a structure represented by Formula 1 below:

[Formula 1]

The glass transition temperature of the hydrocarbon-based resin is 50 ° C to 80 ° C, and when the glass transition temperature is less than the above temperature range, the braking performance is insignificant, and when the glass transition temperature is exceeded, the processability rapidly decreases and becomes a problem. can

The weight average molecular weight of the hydrocarbon-based resin is 600 g/mol or more and 1700 g/mol or less. If it is less than the weight average molecular weight range, the braking performance is insignificant, and if it exceeds the range, fairness may be a problem.

The hydrocarbon-based resin may be included in an amount of 40 to 80 parts by weight based on 100 parts by weight of raw rubber. When the hydrocarbon-based resin is included below the above range, the wet braking index is improved, but the actual braking performance is not improved, and when it is included above the above range, abrasion / rolling resistance (RR) / snow It can be a problem in molding processability due to excessive braking performance, blending processability, and adhesiveness.

The composition according to the present invention may further include a vulcanizing agent, and the vulcanizing agent may be included in an amount of 0.5 to 3.5 parts by weight based on 100 parts by weight of raw rubber. When included below the above range, the abrasion/rolling resistance effect is insignificant, and when included beyond the above range, a problem may occur in scorch time stability.

The vulcanizing agent may be, but is not limited to, preferably 1,6-bis(n,n-dibenzylthiocarbamoyldithio)hexane of Formula 2 below.

[Formula 2]

In Formula 2, -S-(CH ₂ )6-S- has excellent curability and has a relatively long sulfur chain compared to sulfur, so it has flexibility/thermal stability without affecting physical properties, and is an accelerator by generation while decomposing. roles can be combined.

In the tire rubber composition of the present invention, it is preferable to use particles having a specific surface area of 140 m 2 / g or less in terms of dispersion and abrasion, and 1 to 20 parts by weight based on 100 parts by weight of raw rubber, preferably It may be included in 5 to 15 parts by weight.

In the rubber composition for a tire of the present invention, silica which serves to improve physical properties of the rubber composition may be included. The silica may be wet silica (hydrous silicic acid), dry silica (silicic acid anhydride), calcium silicate, aluminum silicate or colloidal silica, and specifically, the effect of improving fracture properties and the compatibility of wet grip is the most It can be excellent wet silica.

The silica may have a nitrogen adsorption specific surface area of 90 to 230 m 2 / g as measured by BET, and contains 60 parts by weight or more and 150 parts by weight or less, preferably 80 to 140 parts by weight, based on 100 parts by weight of raw rubber. can do. If it is less than the above range, it is difficult to develop braking performance, and if it exceeds the above range, fairness (dispersion) problems may occur and wear performance may be greatly reduced.

The composition of the present invention may also further include a vulcanizing agent or silane.

The vulcanizing agent may be sulfur powder, and may include 1 to 3 parts by weight based on 100 parts by weight of raw rubber. When included below the above range, the degree of vulcanization is low, making it difficult to express the desired physical properties.

The silane may include, but is not limited to, bifunctional silane (TESPT, TESPD), mercapto silane, and the like. The silane may be included in an amount of 5 to 15 parts by weight relative to 100 parts by weight of the raw material silica, and when included below the above range, the vulcanization degree is low and the physical properties are lowered. .

In addition, the composition may additionally include components commonly used in the art when manufacturing tires in the art, such as an accelerator.

The tire tread rubber composition according to the present invention has the effect of improving wet road braking performance and snow braking performance, which are trade-off performance, and abrasion performance compared to the prior art. In particular, by including up to 80 parts by weight of styrene butadiene rubber having a low-temperature glass transition temperature, the resin can be further increased compared to the conventional technology at the glass transition temperature secured, thereby maximizing the wet road braking performance compared to the existing technology and snow braking performance A composition can be provided that maintains this.

Hereinafter, the present invention will be described in detail by examples and experimental examples.

However, the following Examples and Experimental Examples are merely illustrative of the present invention, and the contents of the present invention are not limited to the following Examples and Experimental Examples.

<Examples 1 to 4>

As raw material rubber, butadiene rubber, natural rubber, and styrene-butadiene rubber were used, and the styrene-butadiene rubber contained 10 to 20% by weight of styrene and 1 to 30% of vinyl content, and had a glass transition temperature of -70 to -40 ° C. . Hydrogenated hydrocarbon resin (H2 / DCPD / C9 modifier) has a structure of Formula 2 with a glass transition temperature of 50 ° C to 80 ° C and a weight average molecular weight of 600 g / mol or more and 1700 g / mol or less, and the curing agent 1,6-bis(n,n-dibenzylthiocarbamoyldithio)hexane was used, silica and silane were Si-69 ([bis(3-triethoxysilyl)propyl]tetrasulfide=TESPT), carbon black, sulfur , CZ (primary accelerator) and DPG (secondary accelerator) were prepared according to the mixing ratio shown in Table 1 below.

<Comparative Examples 1 to 7>

It was prepared in the same manner as in Example, but with different weights of styrene-butadiene rubber, resin, and vulcanizer, and was prepared according to the mixing ratio of Table 1 below.

<Experiment> Evaluation of snow braking, braking on wet roads, rolling resistance (RR) and wear resistance

Snow braking, braking on a wet road, rolling resistance (RR) and wear resistance were evaluated using Examples 1 to 4 and Comparative Examples 1 to 8. Each evaluation method proceeded as follows, and the experimental results are shown in Table 1.

- Scorch Time (scorch time): Evaluated by a rheometer tester, and unvulcanized rubber was evaluated at 125 ° C. Scorch time means the point at which rubber starts to harden, and if the scorch time is low, it greatly affects manufacturing quality and becomes a problem in tire safety. Therefore, although it depends on the extruder, it should preferably be 15 minutes or more.

- Snow/wet performance, RR performance: evaluated with a DMA (Dynamic Mechanical Analysis) tester, evaluated under Temp Sweep (-100℃ ~ +80℃, 11Hz) conditions, and each performance prediction index value compared. For snow performance, the lower the modulus value of E'-30℃, the better the flow of rubber, and the higher the value of E”0℃ (Loss Modulus/Storage Modulus Ratio), the higher the wet braking performance, the higher the hysteresis. It is advantageous. RR performance is advantageous because the lower the value of Tan60 ° C, the lower the hysteresis.

- Abrasion resistance (Din) performance: Refers to the resistance of rubber to abrasion, and is evaluated by a DIN tester. ASTM (American Society for Testing and Materials) D 5398, ISO 4649, Din 53516 test as an evaluation method for measuring the weight loss value of the surface of a rubber specimen due to friction between the surface of vulcanized rubber and the road surface such as abrasive paper or abrasive stone follow the method

As a result of the experiment, Comparative Example 2 and Comparative Example 3 containing only the low-temperature glass transition temperature SBR without hydrocarbon-based resin had poor braking performance on a wet road. In Comparative Example 4 including low-temperature glass transition temperature SBR and hydrocarbon resin, but outside the scope of the present invention, all performance except for wet braking was deteriorated, and Comparative Example 5 had poor wet braking performance. Low-temperature glass transition temperature SBR and hydrocarbon resins and Comparative Example 6, which were used outside the scope of the present invention, did not show deterioration in performance when an excessive amount of vulcanizer was applied, but had problems with scorch stability, and Comparative Example 7 showed Wear performance has deteriorated.

Claims (5)

In the tread rubber composition for a tire containing a raw material rubber and a hydrocarbon-based resin,
The raw rubber includes 50 to 80 parts by weight of styrene butadiene rubber based on the total weight of the raw rubber,
The hydrocarbon-based resin has a structure of H2 / DCPD / (C9) and contains 40 to 80 parts by weight relative to 100 parts by weight of raw rubber. The tire tread rubber composition according to claim 1, wherein the styrene butadiene rubber contains 10 to 20% by weight of styrene, 1 to 30% by weight of vinyl, and has a glass transition temperature of -70 to -40 ° C. . The tread rubber composition for tires according to claim 1, wherein the hydrocarbon-based resin has a glass transition temperature of 50°C to 80°C and a weight average molecular weight of 600 g/mol or more and 1700 g/mol or less. The tread rubber composition for a tire according to claim 1, wherein the hydrocarbon-based resin has a structure represented by the following Chemical Formula 1:
[Formula 1]

. The tread rubber composition for tires according to claim 1, wherein the composition further comprises 0.5 to 3.5 parts by weight of a vulcanizing agent based on 100 parts by weight of the raw rubber.