RU2365602C1 - Ozone-resistant rubber mixture for radial tyre sides - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to rubber industry, particularly to production of tyres and other rubber technical products. Rubber mixture contains mixture of caoutchoucs, wt.p - isoprene 40-60, butadiene - 25-40 and chlorine-containing ethylene-propylene-diene filled caoutchouc - 15-25. Chlorine-containing ethylene-propylene-diene caoutchouc is obtained by mixing of ethylene-propylene-diene caoutchouc and chlorine- containing hydrocarbon in presence of colloidal silicon dioxide. Rubber mixture also contains sulfur - 1-2, sulfenamide accelerator - 0.5-1.0, zinc oxide - 5-10, technical carbon - 40-60, colophony - 1-3, mineral oil - 5-10, sterol-indene resin - 2-8 and antiscorching agent - santogard PVJ-0.2-1.0 taken per 100 wt.p of caoutchouc mixture.

EFFECT: obtaining tyres which have increased resistance to ozone and thermal aging, as well as increased strength qualities at tension and elongation.

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Description

The invention relates to the formulation of rubber compounds and can be used in the rubber industry in the manufacture of tires and rubber products and, in particular, relates to the production of ozone-resistant rubber compounds used for sidewalls of radial tires.

It is known that rubbers based on synthetic isoprene rubber have properties that are close to natural, but inferior in terms of conditional stresses, conditional tensile strength, and resistance to thermal aging.

Improving the properties of SKI-3 isoprene rubber vulcanizates is achieved by using a low-sulfur vulcanizing group with a combination of accelerators: Altax and diphenylguanidine DFG.

From SU 973563, 11/15/1982 a vulcanizable rubber mixture based on isoprene rubber is known, containing 100 parts by weight of rubber following additives:

Sulfur 1,0 Altax 0.6 DFG 3.0 Technical stearin 1,0 Zinc oxide 5,0 Neozone D 1,1 Carbon DG 100-50

The rubbers from the known rubber mixture are characterized by increased physical and mechanical properties, but have low properties after heat aging: the coefficient of thermal aging at conditional tensile strength (373 K × 48 h) is 0.42-0.52; the coefficient of thermal aging by elongation is 0.20-0.24.

From SU 834015, 05.30.1981, a rubber mixture based on SKI-3 isoprene rubber in combination with SKMS-30 butadiene methyl styrene rubber is known, containing 100 parts by weight of rubber. mixtures of rubbers additives such as zinc oxide, oleic acid, N - nitrosodiphenylamine, rosin, micro wax, neozone D, stabilizer - product 4010 NA, resotropin - modifier RU, rubrax, alrafort, oil PN-6, carbon black PM-100, indene - coumarone resin, carbon black, captax, polyethyleneimine, and bottoms from the production of polyethylene polyamine. The resulting rubbers from this mixture have increased fatigue resistance, but do not have sufficiently high strength properties after aging: the relative elongation after aging of 100 ° C × 48 h is approximately 300%, the tensile strength after aging of 100 ° C × 48 h is 14, 3 MPa. No data on ozone resistance are available.

A rubber compound is known from RU 2290418, 01/01/2004, used for the manufacture of rubber sealing gaskets of ring lining blocks of subway tunnels. The rubber mixture consists in parts by weight of from: isoprene rubber - 45-50, cis1,4-polybutadiene rubber - 11.25-12.5, sulfur - 0.16-0.22, tetramethylthiuram disulfide - 0.84-1.12, white zinc - 2.79 -3.72, diafene FP - 0.56-0.74, stearic acid - 1.12-1.5, phthalic anhydride - 0.56-0.74, carbon black with a specific geometric surface of 50-57 m ² / g - 30.94-41.25, oil bitumen with a softening temperature according to KISH 80-90 ° C - 3.94-5.26, industrial oil - 0.84-1.12. Products from this rubber compound have good strength properties, are durable, but do not have ozone resistance.

From RU 2213750, 10.10.2003, a rubber mixture is known for the cushioning layer of a solid tire based on saturated rubbers - natural rubber 70-80 parts by weight and butadiene rubber 20-30 parts by weight, which includes parts by weight: sulfur 2.0-2.4; vulcanization accelerators - N-cyclohexyl-2-benzthiazolylsulfenamide 0.6-1.0 and 2.2 ¹ -dibenzothiazolyl disulfide 0.1-0.4; zinc oxide 4.0-6.0; stearic acid 1.0-3.0; solid emollient rosin 1.0-3.0; petroleum bitumen 2.0-5.0; vulcanization retardant - phthalic anhydride 0.2-0.5; antioxidant N-phenyl-N ¹ -isopropyl-n-phenylenediamine 1.0-3.0; carbon black 22-26. The specified composition is characterized by low hysteresis losses.

From RU 2122551, 11.27.1998, another rubber compound is known used for cooking chambers. The rubber mixture contains (in parts by weight) SKI-3 80-85 isoprene rubber, SKD 20-15 butadiene rubber, sulfur 0.15-0.25, tetramethylthiuram disulfide 0.8-1.2, 2,2-dibenzothiazole disulfide 0 , 7-1.0, zinc oxide 4.0-6.0, stearic acid 0.3-0.8, oxidized petroleum bitumen (rubrax) 12.0-18.0, rosin 4.0-6.0, N -phenyl N-isopropyl-N-phenylenediamine 1.5-2.5, polymer 2,2,4-trimethyl-1,2-dihydroquinoline 0.7-1.3, phthalic anhydride 0.4-0.6, modifier (product of the interaction of resorcinol with urotropine) 1.0-2.0, carbon black P234 18.0-22.0, carbon black P514 28.0-33.0, additive for recycled waste from vulcanized x rubbers based on saturated rubbers 53,0-30,0. The proposed composition of the rubber compound increases the fatigue resistance and aging resistance of the vulcanizates and the operational endurance of the cooking chambers, but does not provide the necessary ozone resistance to rubber products.

It is known that saturated copolymers of ethylene and propylene (EPA), low-limit copolymers of ethylene, propylene and dienes (EPT) have exceptional oxidation resistance and resistance to a number of aggressive environments. However, the expansion of the fields of application of EPA and EPT is hindered by low mechanical properties (F.F.Koshelev, A.E. Kornev, A.M. Bukanov. General technology of rubber. M., Chemistry, 1978, p. 87-91).

Known, for example, is a vulcanizable rubber mixture based on a combination of rubbers: styrene-butadiene and ethylene-propylene-diene in a ratio of 70:30, respectively (A.E. Kornev et al. Technology of elastomeric materials. M., 2000, Chemistry, p.75 -84). In the presence of high resistance of this mixture to ozone aging, a significant lack of rubbers based on this combination of elastomers still remains low strength properties.

Currently, there is still a need to improve the specific properties of the inner shells of tires without compromising existing performance properties. In order for rubber based on a triple ethylene-propylene-diene copolymer to be used, for example, in a tire tread or sidewall of a tire as part of a multi-component car tire, a suitable triple copolymer must be both sulfur curable and compatible with other rubbers, such like natural rubber and polybutadiene. Further, in order to serve as a pneumatic diaphragm, such as an inner liner of a tire, compositions based on triple copolymers must have airtightness, good adhesion to the tire carcass, such as a styrene-butadiene copolymer carcass, and have acceptable durability . These properties are often difficult to achieve at the same time, since improvement of one can often lead to deterioration of the other.

RU 2161630, 03/02/1999 describes a rubber mixture based on a mixture of isoprene and butadiene rubbers containing a stabilizer consisting of the products of the interaction of a mixture of butylphenols with hexamethidentetramine in a ratio, parts by weight, 100: 2.0-8.5 and polymer 2, 2,4-trimethyl-1,2-dihydroquinoline in the ratio, wt.%: Polymer 2,2,4-trimethyl-1,2-dihydroquinoline 30-70, reaction products 30-70. The mixture of butylphenols is taken in the ratio, wt.%: 2,6-di-tert-butylphenol 0,5-2,0, 2,4-di-tert-butylphenol 22-75, 2,2,4-tri-tert -butylphenol 14-61, mono-, disubstituted butylphenols 10.5-15.0. The rubber mixture based on isoprene and butadiene rubbers has the following composition, parts by weight of: rubber SKI-3 50.0, rubber SKD 50.0, sulfur 1.6, sulfenamide C 0.7, zinc oxide 4.0, stearin acid 2.0, phthalic anhydride 0.5, styrene-indene resin 3.0, octophor N 1.0, oil PN-6Sh 13.0, carbon black P-514 58.0, micro wax 3.0, diafen FP 2 , 0, the specified stabilizer 2.0. Rubber mixtures are prepared in a rubber mixer in two stages, vulcanized at optimum 30 minutes at 151 ° C. The use of such a stabilizer allows improving the protection of rubbers against heat and ozone aging: conditional stress at elongation of 300% is 5.7 MPa, conditional tensile strength at break - 18.5 MPa, thermal aging (100 ° C, 72 hours) - strength retention coefficient 0 , 8, ozone resistance under static tension of 15%, ozone concentration of 10 ^-4 vol.%, 50 ° C, 8 hours - strength preservation factor of 0.86, ozone resistance at a dynamic voltage of 5%, ozone concentration of 10 ^-4 vol.%, 50 ° C, 8 hours - coefficient of conservation of strength of 0.86.

The technical task of the claimed invention is to further increase the resistance of rubbers to ozone and heat aging, as well as increasing the strength at elongation and tension, especially when using it for the manufacture of tire sidewalls. The stated technical problem is achieved in that the ozone-resistant rubber mixture for the sidewalls of tires includes isoprene rubber, butadiene rubber, chlorine-containing ethylene-propylene-diene-filled rubber obtained by the interaction of ethylene-propylene-diene rubber and a chlorinated hydrocarbon of the general formula C _n H _{(2n + 2) x} Cl _x , where n = 10-30, x = 7-24 at a temperature of 80-150 ° C in the presence of colloidal silicon dioxide introduced into the mixture during mixing, and the rubber mixture contains per 100 wt. .h. mixtures of sulfur rubbers, sulfenamide accelerator, stearic acid, zinc oxide, carbon black, rosin, mineral oil, styrene-indene resin and anti-scorching - Santogard PVJ in the following ratio of components in parts by weight:

Isoprene rubber 40.0-60.0 Butadiene rubber 25.0-40.0 The above chlorine ethylene propylene diene filled rubber 15.0-25.0 Sulfur 1.0-2.0 Sulfenamide accelerator 0.5-1.0 Stearic acid 1.0-2.0 Zinc oxide 5.0-10.0 Carbon black 40.0-60.0 Rosin 1.0-3.0 Mineral oil 5.0-10.0 Styrene Indene Resin 2.0-8.0 Santogard PVJ 0.2-1.0

The rubber composition according to the invention contains, for example, SKI-3 isoprene rubber as isoprene rubber; sulfenamide accelerator-N-cyclohexyl-2-benzthiazolyl sulfenamide (sulfenamide C), sulfenamide M (N-oxide-diethylene-2-benzthiazolyl sulfenamide); butadiene rubber - SKD rubber; carbon black - carbon black P-514, P-234; mineral oil - oil PN-6, PN-6Sh; as well as various types of rosins (pine, tall, disproportionate, etc.).

Used chlorine-containing ethylene-propylene-diene rubber (for example, rubber HEPDK-2) is obtained, for example, as follows (RU2296770, 04/10/2007). In a rubber mixer of type RVSD (friction 1: 1.5), ethylene-propylene-diene elastomer (SKEPT-60) is loaded in an amount of 95 parts by weight Then, a chlorinated hydrocarbon of the formula C _n H _{(2n + 2) -x} Cl _{x is} loaded, where n = 20, x = 21 in an amount of 5 parts by weight The mixture is processed at a temperature of 80 ° C and rotor speed, rpm: front - 30, rear - 45. At 11 minutes, 5 parts by weight are loaded into the mixer. colloidal silicic acid (SiO ₂ ). The resulting product contains bound chlorine of 2.0-2.3 wt.%.

The use of the new chlorine-containing rubber HEPDK-2 helps to increase the heat and ozone resistance of rubbers for tire sidewalls while maintaining strength and other specific properties at a fairly high level. The use of HEPDK-2 excludes the use of chemical antioxidants and antioxidants in the formulation of experimental rubbers. Rubber HEPDK-2 in this case plays the role of a polymer "antioxidant antioxidant." It should be noted that chemical antioxidants were not introduced into the experimental rubber compounds for the sidewalls of tires containing HEPDK-2.

Below is an example illustrating the claimed invention, but not limiting it. Table 1 shows an example of the composition of the rubber compound, and table 2 shows the properties of these rubber compounds and vulcanizates based on them. Moreover, the data on the properties are given in comparison with the existing rubber mixture based on a mixture of isoprene and butadiene rubbers for the sidewalls of radial tires 24 rm-422 (Technological regulations of the Moscow tire factory No. 404 sh-89 “Production of passenger radial tires with metal cord breaker”).

Example. Table 1 shows the compositions known for the specified regulations and according to the invention of rubber compounds for sidewalls of radial tires.

Rubber compounds are made in a rubber mixer in two stages. The first stage: the rotation speed of the rubber mixer rotors is 40 rpm, the discharge temperature is 150 ° C, the mixing time is 3 minutes; second stage: rotor speed of 20 rpm, discharge temperature 110 ° C, mixing duration 5 minutes

The vulcanization of rubber compounds is carried out in the press at a temperature of 155 ° C for 20 minutes Plastoelastic, physico-mechanical and some specific properties of rubber compounds and vulcanizates are determined in accordance with existing GOSTs.

Table 1 Components The content of components in parts by weight per 100 parts by weight rubber in the mixture known by regulation according to the invention Isoprene rubber SKI-3 50,0 50,0 SKD butadiene rubber 50,0 30,0 HEPDK-2 chlorine-containing ethylene-propylene-diene rubber 20,0 Carbon black P-514 (GTM-50) 55.0 55.0 PM-6 oil 10.0 10.0 Zinc white 5,0 5,0 Technical stearin 1,0 1,0 Rosin 2.0 2.0 Styrene Indene Resin 3.0 3.0 Protective wax 2.0 - Acetononyl P 2.0 - Sulfur 1,2 1,2 Sulfenamide C 0.8 0.8 Diafen FP 2.0 - Santogard PVJ 0.3 0.3

table 2 Components The content of components in parts by weight per 100 parts by weight rubber in the mixture known by regulation according to the invention Mooney viscosity (120 ° C), conv. units 43 45 Plasticity, conv. units 0.44 0.44 Conditional strength at elongation of 300%, MPa 3,7 7.2 Conditional tensile strength, MPa 15.7 20.5 Elongation at break,% 770 600 The coefficient of thermal aging at 100 ° C in 72 hours By conditional tensile strength 0.56 0.85 Elongation at break 0.63 0.92 Ozone resistance coefficient during dynamic tests (= 20%) 0.52 0.95 Hardness according to TM-2, conv. units 56 60 Bounce Elasticity,% at 20 ° C 41 42 at 100 ° C 47 fifty Crack propagation resistance, thousand cycles > 252 > 252 Dynamic endurance during repeated stretching, thousand cycles > 50 > 50

Thus, as follows from the above data, the rubber mixture according to the invention has high mechanical properties, as well as high resistance to heat aging and ozone resistance, superior in properties to the known rubber compounds used for sidewalls of radial tires according to the well-known technological regulations, as well as in relation to known rubber compound according to RU2161630, containing a special stabilizer against thermal and ozone aging of rubbers.

Claims (1)

Ozone-resistant rubber composition for sidewalls of tires, including isoprene rubber, butadiene rubber, chlorine-containing ethylene-propylene-diene-filled rubber obtained by the interaction of ethylene-propylene-diene rubber and chlorinated hydrocarbon of the general formula C _n H _{(2n + 2) x} Cl _x , where n = 10-30, x = 7-24 at a temperature of 80-150 ° C in the presence of colloidal silicon dioxide introduced into the mixture during their mixing, and the rubber mixture contains per 100 wt.h. mixtures of sulfur rubbers, sulfenamide accelerator, stearic acid, zinc oxide, carbon black, rosin, mineral oil, styrene-indene resin and anti-scorching-Santogard PVJ in the following ratio, wt.h .:
isoprene rubber 40-60 butadiene rubber 25-40 the above chlorine ethylene propylene diene filled rubber 15-25 sulfur 1-2 sulfenamide accelerator 0.5-1.0 stearic acid 1-2 zinc oxide 5-10 carbon black 40-60 rosin 1-3 mineral oil 5-10 styrene indene resin 2-8 Santogard PVJ 0.2-1.0