KR20220048702A - Rubber composition for Tire - Google Patents

Abstract

The present invention relates to a rubber composition for a tire with improved abrasion resistance performance while maintaining braking performance by applying novel material polyketone, and a tire prepared by applying the same to a tread.

Description

Rubber composition for Tire

The present invention relates to a rubber composition for a tire with reduced heat generation and improved wear resistance while maintaining braking performance even without a separate filler including polyketone.

The wear phenomenon of truck and bus tires is a phenomenon in which the surface of the tire tread rubber that is in contact with the ground is worn by the frictional force generated between the tire and the road surface. It is caused by various factors, and since tire wear greatly affects the lifespan of the tire and braking performance, it must have excellent wear resistance in terms of safe driving and reduction of tire replacement cost.

As a method of improving the wear resistance of a conventional tire, a technology including a filler such as silica and/or carbon black has been widely used, and a method of increasing the amount of carbon black added to increase the modulus, and applying carbon black with a small particle diameter Therefore, research on related technologies, such as a method for improving wear resistance, is being actively conducted.

However, in the prior art as described above, by adopting a method of reducing only the particle diameter of carbon black without considering the uniformity of the particles of carbon black, the amount of heat generated during driving increases and there is a risk of deterioration or cracking of tire rubber. There was a disadvantage of reducing the life of the tire. In addition, heat generation and high viscosity occurred during the tire production process, which required strict management of process conditions and increased process costs.

Polyketone, a new material that has recently been spotlighted, is an eco-friendly new polymer material composed of carbon monoxide and olefins (ethylene, propylene), the main culprits of air pollution. Impact strength is 2.3 times better than nylon and chemical resistance is more than 30%, and abrasion resistance is also more than 14 times better than polyacetal (POM), which is known to be the highest level, and ethylene vinyl alcohol (EVOH), which has the best gas barrier properties among existing materials is at the same level as

Polyketone can be largely used for engineering plastics and for super high-strength super fibers. Based on its excellent impact resistance, chemical resistance, and abrasion resistance, it can be applied to high value-added engineering plastics such as interior and exterior materials for automobiles and electric and electronic fields and fuel system parts. It can be used for cords, industrial ropes, belts, etc.

In this regard, in an attempt to introduce polyketone as a reinforcing agent for a rubber composition for a tire, a copolymer consisting of a binary alternating copolymerization of carbon monoxide and ethylene for high-strength fiber use was used in Patent Registration No. 10-2017322. However, when copolymer polyketone is used as a reinforcing agent for a rubber composition for tires, the adhesion to raw rubber is low, and to improve this, a step such as coating a polymer on the surface is required, resulting in a complicated production process and excessive cost. There was a problem that, when applied at a higher weight than raw rubber, the hardness increased excessively, and the elongation and viscoelasticity decreased, making it unsuitable as rubber for tires.

Registered Patent No. 10-2017322 (2019.08.27)

In order to solve the above problems, the present invention is to provide a rubber composition for a tire that has excellent wear resistance and minimizes deterioration and aging of tire rubber by reducing heat generated during driving.

In order to improve the above problems, the present invention provides a rubber composition for tires comprising 100 parts by weight of raw rubber and 5 to 49 parts by weight of polyketone, wherein the polyketone is a compound represented by the following Chemical Formula 1 do.

[Formula 1]

In one embodiment of the present invention, the rubber composition for a tire of the present invention may be surface-modified by treating the polyketone with an acid.

In one embodiment of the present invention, the rubber composition for tires of the present invention may be one obtained by modifying the surface of polyketone using at least one oxidizing agent selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, and styrenesulfonic acid during the acid treatment. there is.

In one embodiment of the present invention, in the rubber composition for a tire of the present invention, the acid treatment reaction condition is an acid concentration of 10 to 30 wt% and a reaction time of 30 minutes to 3 hours to modify the surface of the polyketone. can

In one embodiment of the present invention, the rubber composition for tires of the present invention further comprises 1 to 5 parts by weight of a sulfur vulcanizing agent and 0.1 to 3 parts by weight of a vulcanization accelerator based on 100 parts by weight of the raw rubber. may be doing

In one embodiment of the present invention, the present invention provides a tire characterized in that the rubber composition for a tire is applied to the tread, the undertread, or both the tread and the undertread.

The rubber composition for tires including the polyketone of the present invention can greatly improve abrasion resistance while maintaining driving performance and braking performance.

The rubber composition for tires including polyketone of the present invention can maintain performance suitable for tires, such as hardness, elongation, and viscoelasticity, even when the polyketone content is increased.

In addition, the rubber composition for a tire of the present invention can reduce heat generated in the production process, thereby reducing process cost and optimizing the process.

In addition, the tire using the rubber composition for a tire of the present invention can minimize the deterioration and aging of the tire rubber by reducing heat generated during vehicle driving.

Hereinafter, the configuration of the present invention will be described in more detail through embodiments, examples or experimental examples of the present invention.

The rubber composition for tires of the present invention may contain 5 to 49 parts by weight of polyketone based on 100 parts by weight of the raw rubber. The polyketone content ratio may be preferably 5 to 30 parts by weight, more preferably 5 to 20 parts by weight, and may be 7 to 20 parts by weight.

With respect to 100 parts by weight of the raw rubber, if less than 5 parts by weight of polyketone is included, it does not play a sufficient role as a reinforcing agent, so there is a problem in that the physical properties and wear resistance of the rubber decrease. And as the temperature rises, processability and dispersibility decrease, making it difficult to obtain uniform rubber properties, and the increase in viscosity may cause a scorch problem in the extrusion process.

The polyketone of the present invention is a linear alternating structure, and contains substantially carbon monoxide for each molecule of unsaturated hydrocarbons. Suitable ethylenically unsaturated hydrocarbons for use as synthetic precursors of the polyketone polymers of the present invention have up to 20, preferably up to 10 carbon atoms. In addition, ethylenically unsaturated hydrocarbons include ethene and α-olefins such as propene, 1-butene, iso-butene, 1-hexene, and 1-octene. It is an aliphatic such as or aryl aliphatic containing an aryl substituent on another aliphatic molecule, in particular an aryl substituent on an ethylenically unsaturated carbon atom. Examples of the aryl aliphatic hydrocarbon among the ethylenically unsaturated hydrocarbons include styrene, p-methyl styrene, p-ethyl styrene, and m-isopropyl styrene.

The polyketone polymer preferably used in the present invention is a copolymer of carbon monoxide and ethene or a second ethylenically unsaturated hydrocarbon having at least 3 carbon atoms with carbon monoxide and ethene, particularly α- such as propene It may be a terpolymer with an olefin.

Polyketone is of two types: a copolymer for high-strength fibers, which consists of a binary alternating copolymerization of carbon monoxide and ethylene, and a terpolymer, a terpolymer, which additionally uses propylene for engineering plastics. Although a binary alternating copolymer copolymer for high-strength fibers was used, in the present invention, through research, it was found that the wear of the tire tread can be improved without a separate filler by using the terpolymer terpolymer, which has been used only for engineering plastics. Accordingly, there is provided a rubber composition for a tire using the same and a tire to which the same is applied to a tread or an undertread.

In the present invention, the polyketone represented by the following [Formula 1] may be most preferably used.

[Formula 1]

In Formula 1, the number of repeating monomer units of the polymer may be 10,000 or more. That is, polyketones having a sum of n and m values of 10,000 or more may be used.

The rubber composition for a tire according to the present invention contains the polyketone by mixing it in the form of resin, powder, etc. may be doing

Since the rubber composition for a tire according to the present invention further contains the polyketone, it is possible to reduce the weight of the tire while improving the strength of the tread or undertread, and thus various driving performance advantages can be achieved.

In one embodiment of the present invention, the polyketone contained in the composition for tires of the present invention is characterized in that the surface is modified. As the polyketone surface modification method, acid treatment, base treatment, polymer coating technology, etc. may be used. Among the surface modification methods, the advantages of the acid treatment method are that the treatment time is relatively short and the modification cost is low.

As a characteristic of the polyketone material itself, due to high crystallization for the expression of high strength in the manufacturing process, the free energy of the surface is reduced and the reactivity is reduced due to the small number of reactive groups, which greatly changes the properties of the interface. When the crystallinity of the polyketone is high, the interfacial adhesion with the raw rubber having a hydrophobic surface is low. Therefore, in order to improve the interfacial adhesion properties with rubber while maintaining the high strength of polyketone, it is necessary to introduce various reactive groups using various surface modification methods to impart surface functionality such as wettability and adhesiveness. In the present invention, acid treatment was performed under an ultrasonic bath to improve dispersion of polyketone.

For acid treatment of polyketone, sulfuric acid, hydrochloric acid, phosphoric acid, styrenesulfonic acid, etc. can be used as an oxidizing agent, and phosphoric acid is most preferable as the oxidizing agent because it can modify the polyketone surface at low temperature and in a short time. The oxidizing agent treatment concentration may be 10-30 wt%, preferably 15-25 wt%. If it is less than 10 wt%, there is a fear that the surface modification of the polyketone may not occur sufficiently, and if it is more than 30 wt%, there is a risk that degradation may occur on the surface of the polyketone. When the oxidizing agent treatment concentration is 20 wt%, the pH may be 0.74.

The acid treatment reaction time may be 30 minutes to 3 hours, preferably 1 hour to 2 hours. If the reaction time is less than 30 minutes, there is a fear that the surface modification of the polyketone may not sufficiently occur, and if the reaction time is more than 3 hours, there is a fear that the surface roughness may decrease due to excessive reaction.

The acid treatment reaction temperature may be 20 to 70 °C, preferably 30 to 50 °C. Most preferably, it may be 40° C., and the surface of the polyketone is modified in an ultrasonic bath under the corresponding temperature.

As the phosphoric acid concentration and treatment time increase, the surface roughness increases due to cracks and etching on the surface. can

In one embodiment of the present invention, the raw rubber is a raw rubber used in a conventional rubber composition for a tire, and any of natural rubber, synthetic rubber, rubber mixed with natural rubber and synthetic rubber, etc. may be used.

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

The general natural rubber includes cis-1,4-polyisoprene as a main component, but may also include trans-1,4-polyisoprene according to required characteristics.

The modified natural rubber means that the general natural rubber is modified or refined. For example, examples of the modified natural rubber include epoxidized natural rubber (ENR), deproteinized natural rubber (DPNR), and hydrogenated natural rubber.

The synthetic rubber is solution polymerization styrene-butadiene rubber (S-SBR), emulsion polymerization styrene-butadiene rubber (E-SBR), butadiene rubber (BR), modified butadiene rubber, chlorosulfonated polyethylene rubber, epichlorohydrin rubber, Fluoro rubber, silicone rubber, nitrile rubber, hydrogenated nitrile rubber, nitrile butadiene rubber (NBR), modified nitrile butadiene rubber, chlorinated polyethylene rubber, styrene ethylene butylene styrene (SEBS) rubber, ethylene propylene rubber, ethylene propylene Diene (EPDM) rubber, hypalon rubber, chloroprene rubber, ethylene vinyl acetate rubber, acrylic rubber, hydrin rubber, vinylbenzene chloride styrene butadiene rubber, bromomethyl styrene butyl rubber, maleate styrene butadiene rubber, carboxylate styrene Any one or more selected from butadiene rubber, epoxy isoprene rubber, maleic acid ethylene propylene rubber, nitrile butadiene carboxylic acid rubber, and BIMS (brominated polyisobutyl isoprene-co-paramethyl styrene) may be used.

On the other hand, the rubber composition according to the present invention is a compounding agent that is usually added, for example, N-cyclohexyl-2-benzothiazylsulfenamide as a vulcanization accelerator, sulfur as a vulcanizing agent, stearic acid, zinc oxide, and 1,2 as an antiaging agent for rubber. -Dihydroquinoline or waxy hydrocarbon can be used as needed.

In one embodiment of the present invention, the rubber composition for tires may not contain fillers such as silica, silane, and carbon black.

Carbon black used as a filler may have an iodine specific surface area of 135 to 145 mg/g and a DBP adsorption value of 125 to 135 ml/100 g. In order to compensate for the lack of abrasion resistance of raw rubber such as natural rubber or synthetic rubber, fillers such as silica or carbon black were used. In the rubber composition for tires containing the filler, since it was an important variable to control HBU due to the high exothermicity, various attempts were made to modify carbon black, but in the present invention, the level suitable for commercialization without the use of fillers such as carbon black was achieved. Provided is a rubber composition for a tire that achieves static and dynamic properties, and rather, a new rubber composition for a tire that significantly lowers the degree of heat generation because no filler is used, thereby solving the HBU problem and increasing wear resistance.

In one embodiment of the present invention, the present invention may provide a tire characterized in that the rubber composition for a tire is applied to the tread, the undertread, or both the tread and the undertread of the tire. When the rubber composition for a tire is applied to a tread and/or an under-tread, a tire having low calorific value and excellent wear resistance can be manufactured.

In one embodiment of the present invention, the tire may be applied to an internal combustion engine vehicle including a bus, a truck, or an electric vehicle.

The electric vehicle is characterized by a heavier load compared to the conventional internal combustion engine vehicle, and the torque applied to the tire during driving increases and heat generation due to friction increases. Due to the need for tire application, high wear resistance and low calorific value are required, and the tire of the present invention satisfies all of these and is very suitable for application to medium- and high-load automobiles.

The rubber composition of the present invention may further contain general additives added to general tread rubber compositions, for example, general zinc oxide, stearic acid, sulfur and accelerators.

As the vulcanizing agent, a sulfur-based vulcanizing agent, an organic peroxide, a resin vulcanizing agent, and a metal oxide such as magnesium oxide may be used.

The sulfur-based vulcanizing agent is an inorganic vulcanizing agent such as powdered sulfur, insoluble sulfur, precipitated sulfur, colloidal sulfur, tetramethylthiuram disulfide (TMTD), tetraethyltriuram disulfide (TETD), dithiodi An organic curing agent such as morpholine (dithiodimorpholine) may be used. As the sulfur vulcanizing agent, specifically elemental sulfur or a vulcanizing agent for generating sulfur, for example, amine disulfide, polymeric sulfur, etc. may be used.

The sulfur vulcanizing agent may be used in an amount of 1 to 5 parts by weight based on 100 parts by weight of the raw rubber. Preferably, it may be 1 to 3 parts by weight. When the content of the sulfur vulcanizing agent is less than the above range, tensile properties are low, and when the content of the sulfur vulcanizing agent exceeds the above range, over vulcanization proceeds and aging properties are rapidly decreased.

The vulcanization accelerator refers to an accelerator that promotes a vulcanization rate or a delayed action in the initial vulcanization stage.

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

Examples of the sulfenamide-based vulcanization accelerator include N-cyclohexyl-2-benzothiazylsulfenamide (CBS), N-tert-butyl-2-benzothiazylsulfenamide (TBBS), N,N-dicyclohexyl Any one selected from the group consisting of -2-benzothiazylsulfenamide, N-oxydiethylene-2-benzothiazylsulfenamide, N,N-diisopropyl-2-benzothiazolesulfenamide, and combinations thereof of sulfenamide compounds may be used.

The vulcanization accelerator (TBBS accelerator) may be used in an amount of 0.1 to 3 parts by weight, preferably 0.3 to 1 parts by weight, based on 100 parts by weight of the raw rubber. When the content of the vulcanization accelerator is less than the above range, the vulcanization time becomes long, and when it exceeds the above range, scorch may occur.

The vulcanization accelerator is a compounding agent used in combination with the vulcanization accelerator to perfect the accelerating effect, and any one selected from the group consisting of an inorganic vulcanization accelerator, an organic vulcanization accelerator, and combinations thereof may be used. .

As the inorganic vulcanization accelerator, any one selected from the group consisting of zinc oxide (ZnO), zinc carbonate, magnesium oxide (MgO), lead oxide, potassium hydroxide, and combinations thereof can be used. there is. The organic-based vulcanization accelerator is selected from the group consisting of stearic acid, zinc stearate, palmitic acid, linoleic acid, oleic acid, lauric acid, dibutyl ammonium oleate, derivatives thereof, and combinations thereof. Any one can be used.

In particular, the zinc oxide and the stearic acid can be used together as the vulcanization accelerator, and in this case, the zinc oxide is dissolved in the stearic acid to form an effective complex with the vulcanization accelerator to release advantageous sulfur during the vulcanization reaction It facilitates the crosslinking reaction of rubber by making it.

When the zinc oxide and the stearic acid are used together, 1 to 5 parts by weight and 0.5 to 3 parts by weight 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 an appropriate vulcanization accelerator. When the content of the zinc oxide and the stearic acid is less than the above range, the vulcanization rate is slow and productivity may be reduced.

Hereinafter, the present invention will be described in more detail by way of Examples and Comparative Examples. However, the present invention is not limited by the following examples.

[Examples 1-3, Comparative Examples 1-2]

A rubber composition for a tire tread according to the present invention was prepared by mixing and refining raw materials according to the content ratios shown in Table 1 below.

Polyketone was modified with 20 wt% (pH 0.74) concentration of phosphoric acid as an oxidizing agent in an ultrasonic bath for 60 minutes at 40°C after purchasing Hyosung Poketone's M33R3A000 product.

The composition as shown in Table 1 below, except for sulfur and the vulcanization accelerator, was added to the Banbury mixer, and then kneaded at about 150° C. for 3 minutes. Next, sulfur and a vulcanization accelerator were added to the obtained kneaded material in the amounts shown in Table 1, and then kneaded at about 80°C for 5 minutes using a twin-screw open roll to prepare a rubber composition.

(Unit: parts by weight) item Comparative Example 1 Example 1 Example 2 Example 3 Comparative Example 2 natural rubber 100 100 100 100 100 carbon black 50 polyketone 5 10 20 50 zinc oxide 3 3 3 3 3 stearic acid 2 2 2 2 2 Accelerator (TBBS) 0.7 0.7 0.7 0.7 0.7 Vulcanizing agent (sulfur) 2.5 2.5 2.5 2.5 2.5

[Experimental example]

The rubber compositions of Examples 1 to 3 and Comparative Examples 1 and 2 in Table 1 were evaluated for tensile properties, dynamic properties, Mooney viscosity, DIN wear, and heat generation temperature as described in Table 2, based on the ASTM evaluation method of the evaluation method. evaluated, and the results are shown in Table 2.

item Comparative Example 1 Example 1 Example 2 Example 3 Comparative Example 2 tensile properties Hardness 61 60 63 65 70 300% modulus 83 80 84 95 132 The tensile strength 169 180 197 207 221 elongation 523 524 631 625 650 dynamic properties Tg(℃) -37.0 -36.5 -37.3 -36.5 -35.5 Tanδ0 (0℃) 0.23 0.22 0.27 0.28 0.45 Tanδ0 (70℃) 0.11 0.08 0.08 0.10 0.10 Pattern viscosity (70℃) 79 75 80 84 93 DIN Wear (g) 0.123 0.091 0.097 0.099 0.110 Fever (℃) 42.8 30.2 33.0 34.2 40.8

As shown in Table 2, it can be seen that Examples 1 to 3 have the same or improved tensile properties and dynamic properties as compared to Comparative Examples 1 and 2, and have excellent wear performance and heat generation properties.

Specifically, compared to the comparative example, the tensile strength and elongation were significantly improved in the example, indicating that the tensile properties were more excellent. It can be seen that this is maintained, and the braking force on a wet road surface is improved by increasing the value of 0°C Tangent Delta, and the rolling resistance is improved as the 70°C Tangent Delta value indicating rolling resistance performance decreases. In DIN abrasion performance, when compared to Comparative Example 1, which is a general tire composition, the abrasion was improved by about 20% or more, and the heat generation temperature also decreased by -8.6 to -12.6 ° C. ) can be easily controlled.

In addition, it can be seen that even if the polyketone content is increased (Examples 1 to 3), the degree of increase in hardness is not large, so that tensile strength, elongation, and tangent delta values of 0°C and 70°C are excellently maintained.

Claims (5)

A rubber composition for tires comprising 100 parts by weight of raw rubber and 5 to 49 parts by weight of polyketone,
The polyketone is a rubber composition for a tire, which is a compound represented by the following Chemical Formula 1.
[Formula 1]

The rubber composition for tires according to claim 1, wherein the surface of the polyketone is modified by acid-treating the polyketone. The rubber composition for tires according to claim 2, wherein the surface of the polyketone is modified by using at least one oxidizing agent selected from the group consisting of sulfuric acid, hydrochloric acid, phosphoric acid, and styrenesulfonic acid during the acid treatment. The rubber composition for a tire according to claim 2, wherein the acid treatment reaction condition is that the surface of the polyketone is modified by setting the acid concentration to 10 to 30 wt% and the reaction time to 30 minutes to 3 hours. A tire, characterized in that the rubber composition for a tire according to any one of claims 1 to 4 is applied to the tread, the undertread, or both the tread and the undertread.