RU2495888C2 - Rubber mixture - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a rubber mixture based on a combination of natural and synthetic cis-butadiene rubber, containing silica filler and can be used in the tyre industry for non-studded winter tyre treads. The rubber mixture contains the following, pts.wt: natural rubber SVR-70-80, cis-butadiene rubber - 20-30, sulphur - 1-2, vulcanising group - 8-9, active technical carbon - 5-10, silica filler with specific surface area of 165 m²/g - 30-50, stabiliser based on microcrystalline wax - 1-3, anti-ageing agents - 2-4, process additive - 1-3, softeners - 18-20, binding agent - bis-[3-(triethoxy-silylpropyl]-7-9.

EFFECT: invention increases adhesion of non-studded tyres to an ice-covered and snow-covered surface in a wide temperature range and reduces hysteresis losses.

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Description

The invention relates to a rubber mixture based on a combination of natural and cis-butadiene rubbers containing a silicic acid filler, which can be used in the tire industry to develop rubber formulations for treads with winter patterns of non-studded tires.

A technical solution is known (patent RU 2308469, priority date 01/24/2006), relating to rubber compounds containing silicic acid filler for the manufacture of low-hysteresis treads of fuel-economy tires with improved grip properties. But the technical solution is the closest to the invention in technical essence (patent RU 2129131, priority date 11/08/1995), providing for the use of unsaturated rubbers rubber compound for winter tires, including butadiene rubber containing sulfur, N-cyclohexyl-2 -benzothiazolylsulfenamide, rosin, hydrocarbon resins (coumaronodenine, styrene-indene), petroleum oil, protective wax, N-isopropyl-N'-phenyl-n-phenylenediamine, polymerized 2,2,4-trimethyl-1,2-dihydroquinoline, N -cyclohexylthiophthalimide, techn cal carbon and activator (blend compositions based on zinc salts of fatty acids and zinc oxide). However, this technical solution does not provide sufficient grip with a wet and icy coating and cannot be used in tires without studs.

The advantage of tread rubber compounds based on a combination of natural and synthetic cis-butadiene rubber when filling silicic acid filler is increased wear resistance, low rolling resistance, high adhesion on wet and icy roads, which is one of the main positive factors for tread rubber. Based on the priority requirements for the output characteristics of tires, the requirements for rubbers and materials, as well as for mixing and profiling, have changed. The most relevant are: uniformity of rubber compounds, better processability, durability of tires, as well as environmental friendliness at the stage of production and operation of tires (Pichugin A.M. // Materials science aspects of creating tire rubbers. Scientific publication-Moscow, 2008).

The objective of this invention is to obtain a rubber mixture for the tread of winter tires, providing increased adhesion of tires without spikes with icy and snowy roads in a wide temperature range (including the critical region) to a level as close as possible to the adhesion of tires with spikes, and reducing hysteresis losses. Currently, due to the increased destruction of the road surface with spikes, the question is being raised of improving the formulation of tread rubber for winter tires without spikes. Reduced abrasion extends tire life and is one of the main positive factors for tread rubber.

The objective is achieved by manufacturing a rubber mixture based on natural rubber of the SVR brand and cis-butadiene rubber on a titanium catalyst, including soluble sulfur, vulcanizing group, active carbon black, silicic acid filler with a specific surface of 165 m ² / g, a stabilizer based on microcrystalline wax, softeners, antioxidants, processing aid, bis- [3- (triethoxy) -silylpropyl] -tetrasulfide binding agent, with a ratio of components per 100 parts by weight polymers:

SVR natural rubber 70.0 ÷ 80.0 cis-butadiene rubber on a titanium catalyst 30.0 ÷ 20.0 soluble sulfur 1,0 ÷ 2,0 vulcanizing group 8.0 ÷ 9.0 fillers: - active carbon black 5.0 ÷ 10.0 - silica filler with specific a surface of 165 m ² / g - microcrystalline wax stabilizer 1,0 ÷ 3,0 softeners 18.0 ÷ 20.0 antioxidants 2.0 ÷ 4.0 technological additive 1,0 ÷ 3,0 coupling agent bis- [3- (triethoxy) silylpropyl] - tetrasulfide 7.0 ÷ 9.0

The softener used is a low-temperature ether plasticizer - trioctyl phosphate, which prevents the effect of “oak rubber” even in the most severe frosts. The introduction of hydrocarbon resins as a rubber softener increases the stickiness, which improves its technological characteristics. The use of SVR natural rubber gives the rubber high elasticity and retains grip properties at low temperatures (-5 ÷ 0 ° C). This is due to better wettability due to the presence of polar nitrogen-containing substances. At low temperatures (-20 ° C and below), rubbers based on cis-butadiene rubber on a titanium catalyst have the best set of properties. The use of a bis- [3- (triethoxy) silylpropyl] -tetrasulfide binder, silica filler and rubbers reduces layer slipping and the energy of dissipation of chemical bonds between the filler particles and the rubber matrix. Bis [3- (triethoxy) silylpropyl] tetrasulfide coupling agents rubbers have been used for a long time to ensure compatibility and bonding of dissimilar materials. Without a bonding agent, silica technology could not work. Currently, the choice of the most effective silica filler with a specific surface of 165 m ² / g in combination with a bis- [3- (triethoxy) -silylpropyl] -tetrasulfide binding agent improves the physical properties of tires, such as tread life and rolling resistance ( which directly affects the fuel economy of the car), wear resistance and traction with wet roads and snow. Rubbers based on it have a high dispersing and reinforcing ability. And for better dispersion of active carbon black, as one of the special cases, a technological additive based on a mixture of zinc salts and fatty acids has been selected, which improves the technological characteristics of rubber compounds.

The solution to this problem allows for laboratory road tests of tires of size 205 / 75R15 on a Honda CR-V car with various tread rubber compounds to obtain positive results of the output characteristics of tires when driving on wet and icy surfaces. All tests, and this:

- acceleration from 10-30 km / h (on packed snow);

- acceleration from 10-30 km / h (on ice);

- braking distance on packed snow from 40 km / h;

- braking distance on ice from 40 km / h

- a snake test on packed snow;

- test snake on ice;

- test track closed configuration (on rolled snow);

- expert review

showed a higher level of control for tires with tread rubber compound under options No. 3, 4 in comparison with other options (1, 2) tread rubber compounds (options for the composition of rubber compounds are shown in table 1). The results of the described tests are presented in Fig., Table 2.

The compounding of the rubber mixture according to this technical solution allows for winter tires without studs to improve the grip quality on icy and snowy roads in a wide temperature range (including the critical region) to a level as close as possible to the tire grip with studs due to the use of SVR natural rubber in combination with cis-butadiene rubber on a titanium catalyst, which have the greatest influence on the output properties of rubber compounds (table 3) and tire performance.

The rubber mixture is manufactured on technological equipment in a rubber mixer with interlocking rotors, adjustable gaps between the rotors (master batch line) and a rubber mixer with tangential rotors (final stages line), with additional processing on the rollers according to the 3-stage manufacturing mode.

The possibility of carrying out the invention is illustrated by examples.

The composition of the rubber compounds are presented in table 1.

Tests of rubber compounds and their vulcanizates are carried out according to the known technology used in the tire industry. Results of physical and mechanical tests of a standard rubber compound:

- according to GOST 14925 “Synthetic cis-isoprene rubber” for choosing a natural rubber brand from 3 options. According to the test results of isoprene rubbers (table 4), it is seen that the required level of properties (glass transition temperature and physicomechanical indicators), the most preferred for winter tread is SVR natural rubber;

- according to GOST 19920 "Stereoregular butadiene rubbers" for selection according to the test results of tread rubber compounds based on various rubbers (table 5). The best combination of properties for winter tread is possessed by a rubber mixture based on cis-butadiene rubber on a titanium catalyst.

In order to select the ratio of natural and synthetic cis-butadiene rubbers to formulate an inexpressible tread that operates at low temperatures, the actual glass transition temperature of pure rubbers was determined: natural rubber = -63.1 and cis-butadiene rubber = -104.7 on a DSC204 F1 Phoenix instrument. The results for the glass transition temperature of the rubber mixture are presented in Table 6. The glass transition temperature of the polymers was calculated from the glass transition temperatures of the rubbers and their mass fractions in the mixture according to the Fox equation.

Thus, for the production of non-studded tires that meet the requirements of automobile plants, a rubber mixture has been developed for the tread of winter tires based on a combination of natural rubber of the SVR brand and cis-butadiene rubbers on a titanium catalyst, including silicic acid filler with a specific surface of 165 m ² / g, which allows increase grip on snowy and icy roads in a wide temperature range (including the critical region), reduce hysteresis losses, improve tire performance .

The composition of the rubber compounds

Table 1 Name of material For 100 mass. hour. rubber, mass. hour. prototype 1 option Option 2 3 option 4 option Rubbers: Unsaturated Isoprene Rubber 20-90 - - - Cis-butadiene rubber on a titanium catalyst 10-80 10-80 70-80 30,0 20,0 SVR Natural Rubber - 20-90 20-30 70.0 80.0 Fillers: Active carbon black 55.0 5-10,0 5-10,0 5,0 10.0 Silica filler with a specific surface of 165 m ² / g - 30-50 30-50 30,0 50,0 Technological Additive - 1.0-3.0 1.0-3.0 1,0 3.0 Soluble sulfur 1.9 1,1 1.3 1,0 2.0 Vulcanizing group: 8.0 9.0 Zinc oxide 0.5-10 3.0 2.0 2.0 2,5 N-cyclohexyl-2-benzthiazolylsulfenamide 1,5 1,0 1,0 1,0 1.3 N-cyclohexylthiophthalimide 0.2 0.2 0.2 0.2 0.3 N, N-diphenylguanidine - 1.5-2.0 2.1 2.0 2.1 Dibenzamidodiphenyl Disulfide - 0.3 0.3 0.3 0.4 Stearic acid - 2.0 2.0 1,5 2,4 Coupling agent bis- [3- (triethoxy) silylpropyl] tetrasulfide - 8.0 8.0 7.0 9.0 Softeners: 18.0 20,0 rosin 1,0 - - - - petroleum oil 12.0 - - - - low temperature plasticizer trioctyl phosphate - 9.0 9.0 8.0 9.0 low polycyclic aromatic hydrocarbon naphthenic oil - 5,0 6.0 6.0 7.0 hydrocarbon resins (coumaron-indene, styrene-indene) 2.0 4.0 4.0 4.0 4.0 Microcrystalline Wax Stabilizer 1-3 1-3 1-3 1,0 3.0 Antioxidants: 2.0 4.0 polymerized 2,2,4-trimethyl-1,2-dihydroquinoline 2.0 0.5 0.5 0.5 1,0 N-Isopril-N'-Phenyl-n-Phenylenediamine 1,0 - - - N- (1,3-Dimethylbutyl) N'-phenyl-n-phenylenediamine - 2.0 2.0 1,0 2.0

Tire performance

table 2 The name of indicators Option 1 result / point Option 2 result / point Option 3, 4 result / point Speed properties, with: - acceleration from 10-30 km / h, packed snow 2,45 / 10 2.41 / 10.16 2.4 / 10.20 - acceleration from 10-30 km / h, ice 4.72 / 10 4.65 / 10.15 4.54 / 10.38 braking distance on packed snow from 40 km / h 17.52 / 10 17.2 / 10.18 17.14 / 10.21 braking distance on ice from 40 km / h 36.62 / 10 35.83 / 10.21 35.59 / 10.28 test snake on packed snow, km / h 29.59 / 10 30.22 / 10.21 30.67 / 10.36 test snake on ice, km / h 15.97 / 10 16.19 / 10.15 16.33 / 10.2 test "closed circuit", km / h 34.83 / 10 35.56 / 10.2 35.71 / 10.25 expert rating, points 7.5 / 10 7.5 / 10 7.7 / 10.26

Rubber compound properties

Table 3 The name of indicators Prototype Option 1 Option 2 Option 3.4 Coefficient of friction 0.56 ÷ 0.62 0.66 0.60 0.79 Hysteresis losses, K / E at 100 ° C 0.30 ÷ 0.34 0.339 0.212 0.143

Results of physical and mechanical tests of a standard rubber compound based on isoprene according to GOST 14925 "Synthetic rubber cis-isoprene"

Table 4 The name of indicators 1 var. 2 var. 3, 4 var. Cis-Isoprene Rubber + - - Natural rubber brand STR - + - Natural rubber brand SVR - - + Properties of unvulcanized mixture Viscosity, units Mooney 34.0 34.0 34.0 Properties of vulcanizates Conditional stress at 300% elongation, MPa 0.8 1,1 1.3 Conditional tensile strength, MPa 26.5 25.9 27.0 Elongation at break,% 800,0 740.0 710.0 Bounce Elasticity,% 23 ° C 67.0 68.0 68.0 100 ° C 80.0 80.0 76.0 Shore A hardness, arb. 23 ° C 38,0 39.0 38,0 100 ° C 36.5 38,0 37.0 Tear resistance, kN / m 48.0 45.0 53.0 Abrasion on the device Shoper-Schlob, m ³ / TJ 92.5 89.2 80.8 Frost coefficient: at -45 ° C 0.99 0.93 0.99 at -55 ° C 0.80 0.75 0.73

Results of physical and mechanical tests of a standard rubber compound based on polybutadiene according to GOST 19920 "Stereoregular butadiene rubbers"

Table 5 The name of indicators 1 var. 2 var. 3, 4 var. Cis-polybutadiene rubber on a neodymium catalyst + - - Cis-polybutadiene rubber on lithium catalyst - + - Rubber cis-polybutadiene on a titanium catalyst - - + Properties of unvulcanized mixture Viscosity, units Mooney 77.5 99.0 85.0 Properties of vulcanizates Conditional stress at 300% elongation, MPa 9.3 10.0 10.5 Conditional tensile strength, MPa 18.0 13.7 15.4 Elongation at break,% 510.0 380.0 400,0 Bounce Elasticity,% 23 ° C 44.0 49.0 48.0 100 ° C 56.0 55.0 56.0 Shore A hardness, conv. units 23 ° C 61.0 64.0 64.0 100 ° C 59.0 63.0 63.0 Tear resistance, kN / m 58.0 36.0 41.0 Abrasion on the device Shoper-Schlob, m ³ / TJ 30.5 59,4 33.1 Frost coefficient: at -45 ° C 0.34 0.98 0.76 at -55 ° C 0.02 0.92 0.78

The glass transition temperature of the rubber mixture on the instrument DSC204 F1 Phoenix

Table 6 The ratio of the grades of rubbers SKD (Ti): NK (SVR) Glass transition temperature 0: 100 -63.10 5:95 -65.19 10:90 -67.26 15:85 -69.35 20: 80 -71.42 25:75 -73.51 30:70 -75.58 35:65 -77.67 40:60 -79.74 45:55 -81.83 50:50 -83.90 55:45 -85.99 60:40 -88.06 65:35 -90.15 70:30 -92.22 75:25 -94.31 80:20 -96.38 85:15 -98.47 90:10 -100.54 95: 5 -102.63 100: 0 -104.70

Claims (1)

A rubber compound for tread with a winter pattern of studless tires based on a combination of natural rubber of the SVR brand and cis-butadiene rubber, including sulfur, soluble, vulcanizing group, fillers: active carbon black, silicic acid filler with a specific surface of 165 m ² / g, wax stabilizer microcrystalline, antioxidants, processing aid, emollients, a bis- [3- (triethoxy) -silylpropyl] -tetrasulfide binder in the following ratio of components per 100 parts by weight polymers:
SVR natural rubber 70-80 cis-butadiene rubber 20-30 soluble sulfur 1-2 vulcanizing group 8-9 fillers: active carbon black 5-10 silica filler with specific surface 165 m ² / g 30-50 wax stabilizer microcrystalline 1-3 antioxidants 2-4 technological additive 1-3 softeners 18-20 coupling agent bis- [3- (triethoxy) - silylpropyl] -tetrasulfide 7-9

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