RU2345101C1 - Method of modifying rubber mixes and rubbers - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to the method of modifying general- and special-purpose rubber mixes and rubbers built around high-molecular carbon-chain polymers. Modification of rubber mixes and rubbers is carried out with the help of low-molecular unsaturated polyketones incorporating carbonyl groups and double C=C bonds statistically distributed over the polymeric chain. Modification is effected by adding 0.5 to 50 wt % of low-molecular unsaturated polyketones to the rubber mix, the aforesaid percentage being related to the total content of high-molecular polymer and low-molecular unsaturated polyketone. Note that unsaturated polyketones used for modification contain 0.1 to 16 wt % of oxygen in the form of carbonyl groups and feature a number average molecular weight of 500 to 100000.

EFFECT: improved of technical characteristics of rubber mixes and increased strength characteristics of rubbers produced by vulcanisation of such rubber mixes.

7 cl, 11 tbl, 8 ex

Description

The invention relates to a method for modifying rubber compounds based on high molecular weight carbochain rubbers, as well as general and special purpose rubbers obtained by vulcanizing such rubber compounds.

Known methods for the modification of rubber compounds and their vulcanizates (rubbers) based on high molecular weight carbochain polymers, carried out by adding low molecular weight polymers (oligomers) to rubber mixtures.

In the article [F.E.Kuperman, B.S. Turov, K.E. Gavshinova, S.V. Novikov. Properties of SKD rubber obtained by mixing high molecular weight and low molecular weight cis-polybutadiene // Rubber and Rubber, 1971, No. 2, 3] the effect of low molecular weight cis-polybutadiene on the properties of rubber mixtures and rubbers based on high molecular weight polybutadiene rubber SKD is studied. Low molecular weight polybutadiene was obtained by solution polymerization of butadiene in the presence of a Ziegler-Natta catalyst based on titanium halides and triisobutylaluminum. It is shown that the addition of low molecular weight rubber improves the technological properties of rubber compounds, in particular their milling. When adding from 10 to 20 wt.% Low molecular weight polybutadiene with respect to the total amount of low molecular weight and high molecular weight rubbers, the strength and wear resistance of rubbers practically do not change. A decrease in the molecular weight of the oligomer is accompanied by a decrease in rubber hardness and an increase in elongation and tear resistance.

In the article [F.E.Kuperman, B.S. Turov, T.N. Ukhina, G.I. Kostrykina. The effect of additives of low molecular weight polybutadiene on the properties of mixtures and rubbers based on SKD rubber // Rubber and Rubber, 1976, No. 9, 13] the effect of low molecular weight polybutadiene rubbers with different molecular weights on the properties of mixtures and rubbers based on high molecular weight polybutadiene rubber SKD is studied. Low molecular weight polybutadiene was obtained by polymerization of butadiene in solution in the presence of a catalytic system based on compounds of nickel and alkylaluminium chlorides. It is shown that the introduction of 5-10 wt.% Low molecular weight polybutadiene into the rubber can significantly improve the technological properties of the mixtures without compromising the strength and wear resistance of rubbers. The addition of large quantities of low molecular weight polymer impairs the mechanical characteristics of the rubber.

In the article [I. B. Belov, A. P. Savinsky, O. M. Shibanov. Low molecular weight polymers of diene hydrocarbons and compositions based on them // Rubber and Rubber, 1971, No. 8, 32] studied the effect of liquid cis-polybutadiene rubber with a molecular weight of 2000 on the properties of rubber compounds and rubbers based on high molecular weight butadiene-α-methylstyrene rubber SKSM- 10. It is shown that good technological properties of the rubber compound and optimal properties of rubbers are achieved with the introduction of 30 wt.% Oligomer in relation to the basic rubber. The resulting modified rubber has lower hardness, somewhat greater frost resistance, higher elongation compared to unmodified vulcanizate with almost the same tensile strength and elasticity.

In the patent [US No. 6472461, C08K 3/34, 10.29.2002] a method for modifying tread rubbers based on diene rubbers by introducing liquid polybutadiene rubber with a weight average molecular weight of 5,000 to 30,000 in an amount of from 6 to 50 wt. .% (30-70 wt.% Of the total content of high molecular weight and liquid rubbers). The indicated low molecular weight polybutadiene with a cis-1,4-unit content of 60 to 98% was autoclaved by solution polymerization of butadiene in the presence of diethylaluminum monochloride and nickel octoate.

In the patent [US No. 6242523, C08J3 / 00, 5.06.2001] a method for modifying tread rubbers based on diene rubbers by introducing liquid polybutadiene with a high content (40-95%) of vinyl units and number average molecular weight from 1000 into the initial rubber mixture is described up to 20,000 in an amount of from 5 to 50 wt.%.

The patent [US No. 6070634, B60C 1/00, July 6, 2000] describes the use of a liquid isoprene-butadiene block copolymer with a medium viscosity molecular weight of 25,000 to 100,000 for the modification of rubber compounds and rubbers based on diene rubbers. For modification, from 0.5 to 40 wt.%, Preferably from 1.5 to 15 wt.% Of a liquid copolymer was added to the initial rubber mixture.

In the patents [US No. 6204320, C08J 27/00, 03.20.2001; US No. 6562895, C08J 27/00, 05/13/2003] describes the use of liquid isoprene-butadiene rubber with a number average molecular weight of 3000 to 50,000 for the modification of tread rubbers based on diene rubbers. To do this, from 4 to 40 wt.% Liquid rubber was added to the original rubber mixture. The specified liquid isoprene-butadiene rubber was prepared by solution copolymerization of isoprene and 1,3-butadiene in the presence of a lithium organic initiator.

The disadvantage of these methods is the complexity of the methods of obtaining used for the modification of low molecular weight polymers. They are mainly obtained by solution polymerization methods, which require the use of expensive and complex catalysts, co-catalysts and initiators. The main disadvantage of these methods is the insufficiently high strength of the rubber obtained as a result of the modification. This is due to the fact that the low molecular weight polymers used to modify these methods do not contain oxygen-containing functional groups, the presence of which allows the creation of high-strength polymer compositions.

In the patent [US No. 6251992, C08L 29/02, B60C 11/00, 06/26/2001] a method for modifying rubber compounds and tread rubber based on diene rubbers by introducing liquid polyalkylene with terminal hydroxyl groups with a molecular weight from 250 to 70,000 in an amount of from 1 to 50 wt.%. The specified low molecular weight polymer was prepared in two stages by anionic polymerization of isoprene and / or 1,3-butadiene, followed by hydrogenation of the obtained polymer.

The main disadvantages of this method are the complex two-stage method for producing the low molecular weight polymer used, as well as the insufficiently high strength of the resulting rubbers. This is due to the very low content of oxygen-containing (in this case, hydroxyl) functional groups in the polymer used, which are located only at the ends of the polymer chain.

The invention solves the problem of improving the technological characteristics of rubber compounds, as well as increasing the strength and other characteristics of rubber obtained by vulcanization of such rubber compounds.

The present invention describes a new method for modifying rubber compounds and rubbers based on high molecular weight carbochain rubbers.

The proposed method for the modification of rubber compounds based on high molecular weight carbochain rubbers, as well as general and special purpose rubbers obtained by vulcanization of such mixtures, is carried out by adding a low molecular weight polymer containing functional groups to the rubber mixture, and a low molecular weight unsaturated polyketone containing carbonyl groups and double carbon-carbon bonds.

For modification, a low molecular weight unsaturated polyketone obtained by oxygenation of nitrous oxide with high molecular weight polymers containing double carbon-carbon bonds is used.

For modification, a low molecular weight unsaturated polyketone obtained by oxygenation with nitrous oxide of butadiene, or isoprene, or butadiene-isoprene, or butadiene-nitrile rubbers is used.

From 0.5 to 50 wt.% Low molecular weight unsaturated polyketone relative to the total amount of high molecular weight carbochain rubber and low molecular weight unsaturated polyketone are added to the rubber mixture.

For modification, a low molecular weight unsaturated polyketone containing from 0.1 to 16 wt.% Oxygen in the form of carbonyl groups and having a number average molecular weight of 500 to 100,000 is used.

For modification, a combination of low molecular weight unsaturated polyketones of various compositions is added to the rubber composition.

Low molecular weight unsaturated polyketones are used to modify the lining rubber composition in order to increase the bond strength of lining rubber with tire cord and dynamic fatigue endurance of rubber.

According to the proposed method, the modification is carried out by adding low molecular weight unsaturated polyketones to the rubber mixture, a new type of functional low molecular weight polymers having carbonyl C = 0 groups statistically distributed along the polymer chain, as well as double carbon-carbon bonds [K.A.Dubkov, et al., J. Polym. Sci., Part A: Polym. Chem. 44 (2006) 2510].

Saturated polyketones are widely known, which are obtained by catalytic copolymerization of carbon monoxide with one or two types of lower olefins in the presence of homogeneous complex palladium complexes [Drent E., Budzelaar R.N.M. // Chem. Rev. 96 (1996), 663]. In contrast to such polymers, unsaturated polyketones used in the proposed method with the necessary carbonyl groups and molecular weights can be obtained by non-catalytic oxygenation with nitrous oxide (N ₂ O) polymers containing carbon-carbon double bonds [Patent RU No. 2230754, 27.08 .2004, Panov G.I. and etc.; Patent RU No. 2235102, 08.27.2004; Parmon V.N. and etc.; Patent RU No. 2283849, 09.20.2006, Panov G.I. and etc.; Patent RU No. 2280044, 07.20.2006, Panov G.I. and etc.; application US 2006/0293465 A1, KADubkov, et al., December 28, 2006].

According to this method, the oxygenation of unsaturated polymers with nitrous oxide is carried out at a temperature of 50-350 ° C and a pressure of N ₂ O 0.01-100 at. Varying the oxygenation conditions allows the molecular weight of the resulting unsaturated polyketones and the content of carbonyl groups in them to be widely controlled. Thus, this method allows you to further adjust the ratio of carbonyl groups and carbon-carbon double bonds in the molecule of unsaturated polyketone [KADubkov, et al., J. Polym. Sci., Part A: Polym. Chem. 44 (2006) 2510-2520]. This provides important advantages for regulating the properties of rubber compounds and rubbers modified with such unsaturated polyketones.

In addition, this simple non-catalytic method allows to obtain unsaturated polyketones from various types of unsaturated polymers, for example, from butadiene, or isoprene, or butadiene-isoprene, or styrene-butadiene, butadiene-nitrile and other rubbers. Accordingly, the unsaturated polyketones obtained, in addition to units with carbonyl groups, can contain either butadiene, or isoprene, or butadiene-nitrile, or other types of units with C = C bonds. Therefore, an important advantage of the proposed method is the ease of selecting the most suitable type of unsaturated polyketone for modification, which can be obtained by oxygenation of nitrous oxide with the corresponding unsaturated polymer. This creates additional opportunities for modifying rubber compounds and rubbers and provides high compatibility of unsaturated polyketones with different types of high molecular weight rubbers in the composition of rubber compositions.

Used in the proposed method, low molecular weight unsaturated polyketones have a set of important characteristics. Due to the presence of polar carbonyl groups in their composition, they have high adhesion to various materials. In addition, due to their relatively low viscosity, they can be mixed with various ingredients and excipients. Therefore, their introduction into the rubber composition allows to obtain rubber compounds and rubbers with improved technological and operational characteristics, in particular with improved adhesive and strength properties. Such properties are especially important in the case of rubber-cord systems where a high bond strength of the lining rubbers with the cord is required. In addition to carbonyl groups, these functional polymers contain carbon-carbon double bonds. Therefore, unsaturated polyketones have good compatibility with different types of high molecular weight rubbers, and are also easily vulcanized in rubber compositions.

According to the proposed method, unsaturated polyketones, which can be used to modify rubber compounds and rubbers, can contain from 0.1 to 16 wt.% Oxygen in the form of carbonyl groups and have a number average molecular weight of 500 to 100,000. They are liquid oligomers or flowable polymers.

In accordance with this invention, the modification of rubber compounds based on high molecular weight carbochain rubbers, as well as general and special purpose rubbers obtained by vulcanization of such rubber compounds, is carried out by adding a low molecular weight unsaturated polyketone to the rubber mixture or a combination of unsaturated polyketones. The amount of low molecular weight unsaturated polyketone or a combination of unsaturated polyketones added to the rubber mixture for modification is from 0.5 to 50 wt.% With respect to the total amount of high molecular weight rubber and low molecular weight unsaturated polyketone.

General and special purpose rubbers that can be modified by the proposed method include vulcanizates of rubber compounds based on high molecular weight carbochain rubbers of various types, for example natural rubber (NR), as well as synthetic rubbers such as stereoregular polyisoprene rubber (SKI), stereoregular polybutadiene rubber rubber (SKD), nitrile butadiene rubbers (BNKS), etc. Rubber of these types are widely used in the manufacture of tires, frost-resistant, oil-resistant and other rubber- technical products.

According to this invention, a modified rubber composition can be prepared by simple simultaneous or sequential mixing of all necessary components (high molecular weight rubber, low molecular weight unsaturated polyketone, fillers, vulcanizing agents, plasticizers, etc.). Modified rubber composition can also be prepared by adding low molecular weight rubber to the finished rubber composition with their subsequent mixing. Mixing of the components at all stages of modification and manufacture of the rubber composition is carried out on standard mixing equipment, for example, rollers, rotor or screw mixers.

In the General case, the modification of rubber compounds and rubber is as follows. All components of the mixture are pre-dosed. A low molecular weight unsaturated polyketone or a combination of unsaturated polyketones is mixed with high molecular weight carbochain rubber. Next, the modified carbochain rubber is mixed with high molecular weight diene hydrocarbons, fillers, plasticizers, stabilizers, vulcanizing additives, pigments. The resulting rubber composition is molded and subjected to isothermal vulcanization to obtain rubber.

In accordance with this invention, modification with low molecular weight unsaturated polyketones reduces the viscosity of rubber compounds based on high molecular weight carbochain polymers. This improves the technological properties of rubber compounds and facilitates their processing at the stage of mixing the components and molding of various products. In addition, this modification provides an increase in the strength characteristics of rubbers obtained by vulcanization of rubber compounds. In particular, the modification of lining rubber mixtures according to the proposed method can significantly increase the bond strength of lining rubber with tire cord.

The invention is illustrated by the following examples.

Example 1

This example is comparative. It demonstrates the modification of the rubber mixture and rubber based on the high molecular weight carbidechain cis-1,4-polybutadiene rubber SKD-ND (Voronezhsintezkauchuk), which are used for the manufacture of sidewalls of passenger tires. Modification is carried out using low molecular weight polybutadiene rubber (known method) and low molecular weight unsaturated polyketone (proposed method). The compositions of the standard rubber compound according to GOST 19920.19-74 and modified mixtures are shown in table 1.

For modification according to the known method using serial low molecular weight polybutadiene PB (VF NII SK, Voronezh) obtained by solution polymerization of butadiene in the presence of Ziegler-Natta catalysts. This liquid oligomer has a molecular weight of M _n = 1000 (M _w / M _n = 3.0) and contains 30.7% of 1,2 units. Unlike unsaturated polyketone, this oligomer does not have oxygen-containing functional groups.

For modification according to the inventive method using a low molecular weight unsaturated polyketone NP-PB-9.9 obtained by Pat.RU №2230754 nitrous oxide by the oxygenation of stereoregular cis-1,4-polybutadiene rubber (M _n = _{128000, M w / M n = 2.2} ). This unsaturated polyketone is a viscous liquid oligomer with a molecular weight of M _n = 2200 (M _w / M _n = 2.5) and contains 9.9 wt.% Oxygen in the form of carbonyl C = O groups. It consists of units with carbonyl groups and butadiene units

Table 1.
The composition of the rubber mixture based on rubber SKD-ND Component Standard mix The composition of the rubber compound (g) Modified mixture with the addition of NP-PB-9.9 Modified mixture with the addition of PB Low molecular weight polybutadiene PB - - twenty Low molecular weight polyketone NP-PB-9.9 - twenty - Rubber SKD-ND 400 400 400 Oil bitumen twenty twenty twenty Zinc oxide twenty twenty twenty Stearic acid 8 8 8 Sulfur 8 8 8 Sulfenamide C 2,8 2,8 2,8 Carbon black N 330 180 180 180

The modification is carried out by adding 20 g of the indicated low molecular weight polymers to the rubber mixture (Table 1), which is 4.8 wt.% With respect to the total amount of the main high molecular weight rubber and low molecular weight polymer. To do this, all the components are dosed and sequentially mixed on the rollers. First, a mixture of high molecular weight rubber and a low molecular weight polymer is mixed. Then, the remaining components are successively added to the resulting mixture (table 1). The total mixing time is 20 minutes The measurement of the vulcanization-kinetic characteristics of the mixtures is carried out at a temperature of 143 ° C.

The data shown in table 2 show that the modification of low molecular weight polymers leads to rubber mixtures with a lower viscosity compared to a standard mixture, which is reflected in a decrease in minimum torque. In addition, the modification reduces the rate of vulcanization. This gives advantages in the manufacture of rubber products with a complex profile.

Table 2.
Vulcanization-kinetic characteristics of rubber compounds based on rubber SKD-ND Indicators Standard mix Modified mixture with the addition of NP-PB-9.9 with the addition of PB Minimum Torque (N * m) 0.70 0.64 0.59 The rate of vulcanization (% / min.) 10.5 7.7 6.2

Table 3 shows the characteristics of the rubber obtained by vulcanization of raw rubber compounds at a temperature of 143 ° C. It is seen that the modification of rubber using low molecular weight unsaturated polyketone according to the proposed method provides several advantages compared with low molecular weight polybutadiene without functional groups (known method), as well as in comparison with an elastomeric composition of standard composition.

Table 3.
Physico-mechanical characteristics of vulcanizates based on rubber SKD-ND Indicators Standard rubber Modified rubber with the addition of NP-PB-9.9 (the proposed method) with the addition of PB (known method) Elongation at break (%) 500 600 525 Tensile Strength (MPa) 23,4 25,2 21,4 Tear resistance (kN / m) 57.8 46.5 42.5 Shore hardness under normal conditions (conventional units) 57 56 56 Elasticity under normal conditions (%) 46 45 45 Frost resistance (° C) -60 -60 -60

The proposed modification method provides rubber with the highest elongation at break (600%) and with the highest tensile strength (25.2 MPa). In addition, the proposed method provides rubber with a higher tear resistance (46.5 kN / m) compared with the known modification method (42.5 kN / m). It is important that a significant improvement in the strength characteristics of rubber modified by the proposed method is not accompanied by a change in vulcanizate properties such as hardness, elasticity and frost resistance (Table 3).

Example 2

This example is similar to example 1 with the difference that the low molecular weight unsaturated polyketone NP-PB-9.9 (M _n = 2200, M _w / M _n = 2.5, 9.9 wt.% Oxygen) is used to modify the rubber mixture and rubber based on high molecular weight carbene chain butadiene -Nitrile rubber BNKS-28AMN (Krasnoyarsk plant SK). Such compositions are used for the manufacture of oil-resistant rubber products. The compositions of the standard rubber compound according to TU 38.30313-2000 and the modified mixture are shown in table 4.

The modification is carried out by adding 20 g of the specified unsaturated polyketone to the rubber mixture, which is 4.8 wt.% With respect to the total amount of the main high molecular weight nitrile butadiene rubber and low molecular weight unsaturated polyketone.

Table 4.
The composition of the rubber mixture based on rubber BNKS-28AMN Component The composition of the rubber compound (g) Standard mix Modified mixture with the addition of NP-PB-9.9 Low molecular weight polyketone NP-PB-9.9 - twenty Rubber BNKS28AMN 400 400 Zinc oxide 12 12 Stearic acid four four Sulfur 6 6 Sulfenamide C 2,8 2,8 Carbon black P 324 160 160

Table 5 shows that the modification of the proposed method improves the performance of the rubber compound. The addition of a low molecular weight unsaturated polyketone lowers the viscosity of the rubber compound, which results in a decrease in minimum torque, and also significantly reduces the rate of vulcanization compared to a standard mixture.

Table 5.
Vulcanization-kinetic characteristics of rubber mixtures based on rubber BNKS Indicators Standard mix Modified mixture with the addition of NP-PB-9.9 Minimum Torque (N * m) 0.4 0.36 The rate of vulcanization (% / min.) 18.1 5.8

The characteristics of the rubber obtained by vulcanization of raw rubber compounds at a temperature of 143 ° C are shown in table 6. It can be seen that the modification of rubber according to the proposed method provides several advantages compared to the elastomeric composition of a standard composition. The addition of low molecular weight unsaturated polyketone leads to a significant increase in elongation (670%) and tear resistance (46.3 kN / m), as well as an increase in the frost resistance of rubber. Such properties of rubber as tensile strength, hardness and elasticity are practically unchanged. An additional positive effect of the modification is a decrease in the rubber aging coefficient, which is expressed in a decrease in the change in elongation after thermooxidative aging at 100 ° C for 48 hours.

Table 6.
Physico-mechanical characteristics of vulcanizates based on rubber BNKS Indicators Standard rubber Modified rubber with the addition of NP-PB-9.9 Elongation at break (%) 535 670 Tear resistance (kN / m) 38 46.3 Tensile Strength (MPa) 17.3 17.3 Shore hardness under normal conditions (conventional units) 59 58 Elasticity under normal conditions (%) 28 29th Frost resistance (° C) -52 -54 Change in elongation at break after thermo-oxidative aging 37.6 22.4

Example 3

This example is similar to example 1 with the difference that the low molecular weight unsaturated polyketone NP-PB-9.9 (M _n = 2200, M _w / M _n = 2.5, 9.9 wt.% Oxygen) is used to modify casing rubber and cis-based rubber 1,4-polyisoprene rubber SKI-3. Such compositions are used for the manufacture of rubber tire systems. For comparison, the example was also modified according to the known method using a low molecular weight polymer PDI-1K with terminal hydroxyl groups (Sterlitamak Petrochemical Plant, M _n = 3300, M _w / M _n = 3.5, mass fraction of hydroxyl groups 0.8 wt.%). This oligomer is obtained by solution copolymerization of butadiene and isoprene.

The compositions of the standard rubber compound and modified mixtures are shown in Table 7. The modification is carried out by adding 10 g of the indicated low molecular weight polymers to the rubber compound, which is 4.8 wt.% With respect to the total amount of the main high molecular weight polyisoprene rubber and low molecular weight polymer.

From table 8 it is seen that the modification according to the proposed and known method does not change the minimum torque and, accordingly, the viscosity of the rubber compound. The cure rate in both cases also remains virtually unchanged compared to the standard composition of the mixture, which is a positive result for this type of composition.

Table 7.
The composition of the coating mixture based on rubber SKI-3 Component Standard mix The composition of the rubber compound (g) Modified mixture with the addition of NP-PB-9.9 Modified mixture with the addition of PDI-1 K Oligomer PDI-1 K - - 10 Low molecular weight polyketone NP-PB-9.9 - 10 - Rubber SKI-3 200 200 200 Sulfur gas 5,6 5,6 5,6 Zinc White fourteen fourteen fourteen Stearic acid 2 2 2 Sulfenamide M 2 2 2 Santogard PVI 0.4 0.4 0.4 Pine Rosin four four four Hydrocarbon resins four four four Softener ASMG 10 10 10 PN-6sh oil 6 6 6 White soot BS-120 10 10 RU modifier four four four Diafen FP 2 2 2 Carbon black 110 110 110

Table 8.
Vulcanization-kinetic characteristics of lining rubber compounds based on rubber SKI-3 Indicators Standard mix Modified mixture with the addition of NP-PB-9.9 with the addition of PDI-1K Minimum Torque (N * m) 0.25 0.25 0.25 The rate of vulcanization (% / min.) 8.3 8.1 8.1

The characteristics of the rubber obtained by vulcanization of crude rubber compounds at a temperature of 143 ° C are shown in table 9. It can be seen that the modification of rubber using a low molecular weight unsaturated polyketone by the proposed method provides several advantages compared to a low molecular weight polymer with terminal hydroxyl groups (known method), as well as compared with an elastomeric composition of a standard composition. The proposed modification method provides rubber with the highest elongation at break (600%) and with the highest frost resistance (-55 ° C). When low molecular weight unsaturated polyketone is introduced into the rubber, the tensile strength, hardness and elasticity do not change compared to the standard composition, but higher compared to rubber modified by the known method.

Table 9.
Physico-mechanical characteristics of rubber-based vulcanizates SKI-3 Indicators Standard rubber Modified rubber with the addition of NP-PB-9.9 (the proposed method) with the addition of PDI-1K (known method) Elongation at break (%) 575 600 580 Tensile Strength (MPa) 17 17 16.5 The bond strength of rubber with steel cord 4L30, (N) 156 205 150 Shore hardness under normal conditions (conventional units) 73 73 71 Elasticity under normal conditions (%) 25 25 21 Frost resistance (° C) -53 -55 -53 Dynamic fatigue endurance (cycles) 57200 69000 55400

The most important positive effect of the modification according to the proposed method is a significant increase in the bond strength of the lining rubber with the 4L30 steel cord. When modified by the proposed method, the bond strength of the lining rubber with the 4L30 metal cord is 205 N, which is higher compared to the standard composition (bond strength 156 N). When modified by a known method, this indicator, on the contrary, worsens and amounts to 150 N.

Another important positive effect of the modification according to the proposed method is a significant increase in the dynamic fatigue endurance of rubber during repeated deformations (150%). When modified by the proposed method, this value is 69,000 cycles, which is higher compared to the standard composition (57,200 cycles). When modified by a known method, this indicator, on the contrary, worsens and amounts to 55400 cycles.

Example 4

This example is similar to example 3 with the difference that low-molecular unsaturated polyketone NP-PB-14.7 with a higher content of carbonyl groups is used to modify the lining rubber mixture and rubber (oxygen content 14.7 wt.%). This unsaturated polyketone obtained by Pat. RU No. 2230754 by oxygenation with nitrous oxide of cis-1,4-polybutadiene rubber and is a viscous liquid oligomer with a molecular weight of M _n = 800 (M _w / M _n = 2.1).

The modification is carried out by adding 1 g of the indicated liquid oligomer to the standard rubber mixture, which is 0.5 wt.% With respect to the total amount of the main high molecular weight rubber and low molecular weight polyketone. As a result of the modification by this method, the bond strength of the lining rubber with the steel cord increases compared to the standard composition and reaches 175 N (table 10).

The dynamic fatigue endurance of rubber also increases compared to a standard composition (57204 cycles) and reaches 74,630 cycles (Table 10). The properties of the vulcanizate, such as tensile strength, hardness and elasticity, do not change compared to the standard composition.

Table 10.
The bond strength of rubber-based rubber SKI-3 with steel cord Type of modifying polyketone The amount of polyketone in the rubber compound (%) The bond strength of rubber with steel cord (N) Dynamic fatigue endurance (cycles) Standard mix 0 156 57200 Example 4 NP-PB-14.7 0.5 175 74630 Example 5 NP-PB-0.2 fifty 180 80630 Example 6 NP-PI-3.9 twenty 230 86020 Example 7 Combination NP-PB-9.9 and NP-PI-1.7 9.6 220 82330

Example 5

This example is similar to example 3 with the difference that low-molecular unsaturated polyketone NP-PB-0.2 with a lower content of carbonyl groups is used to modify the lining rubber mixture and rubber (oxygen content 0.2 wt.%). This unsaturated polyketone obtained by Pat. RU No. 2235102 by oxygenation with nitrous oxide of cis-1,4-polybutadiene rubber and is a polymer with a molecular weight of M _n = 92000 (M _w / M _n = 2.0).

The modification is carried out by introducing into the rubber mixture 50 wt.% Of the specified unsaturated polyketone in relation to the total amount of high molecular weight rubber and low molecular weight polyketone. To do this, prepare a rubber mixture containing 100 g of unsaturated polyketone and 100 g of polyisoprene rubber. The content of the remaining components does not differ from the standard composition (table 7).

As a result of this modification, the bond strength of the lining rubber with the steel cord reaches 180 N, which is higher compared to the standard composition (table 10). Dynamic fatigue endurance of rubber also increases compared to a standard composition and reaches 80630 cycles. The properties of the vulcanizate, such as tensile strength, hardness and elasticity, do not change compared to the standard composition.

Example 6

This example is similar to example 3 with the difference that low-molecular unsaturated polyketone NP-PI-3.9 (oxygen content 3.9 wt.%) Obtained according to Pat. RU No. 2230754 by oxygenation with nitrous oxide of cis-1,4-polyisoprene rubber (M _n = 380000, M _w / M _n = 2.9). This unsaturated polyketone contains units with carbonyl groups and isoprene units and is a viscous liquid oligomer with a molecular weight of M _n = 1000 (M _w / M _n = 1.9).

The modification is carried out by introducing into the rubber mixture 20 wt.% Of the specified unsaturated polyketone with respect to the total amount of high molecular weight rubber and low molecular weight polyketone. To do this, prepare a rubber mixture containing 40 g of unsaturated polyketone and 160 g of polyisoprene rubber. The content of the remaining components does not differ from the standard composition (table 7).

As a result of the modification in this way, the bond strength of the lining rubber with the steel cord increases compared to the standard composition and reaches 230 N (table 10). Dynamic fatigue endurance of rubber also increases compared to a standard composition and reaches 86,020 cycles. The properties of the vulcanizate, such as tensile strength, hardness and elasticity, do not change compared to the standard composition.

Example 7

This example is similar to example 3 with the difference that the modification of the lining rubber mixture and rubber is carried out using a combination of low molecular weight unsaturated polyketones. For modification, liquid unsaturated polyketones NP-PB-9.9 (M _n = 2200, M _w / M _n = 2.5, oxygen content 9.9 wt.%) And NP-PI-1.7 (M _n = 2800, M _w / M _n = 1.6, oxygen content 1.7 wt.%) Obtained according to Pat.RU No. 2230754 by oxygenation with nitrous oxide, respectively cis-1,4-polybutadiene and cis-1,4-polyisoprene rubbers.

The modification is carried out by introducing into the rubber mixture 4.8% by weight of the indicated unsaturated polyketones with respect to the total amount of the main high molecular weight rubber and low molecular weight polyketones. To do this, prepare a rubber mixture containing 10 g of unsaturated polyketone NP-PB-9.9, 10 g of unsaturated polyketone NP-PI-1.7 and 180 g of polyisoprene rubber. The content of the remaining components does not differ from the standard composition (table 7).

As a result of the modification by this method, the bond strength of the lining rubber with the steel cord increases compared to the standard composition and reaches 220 N (table 10). Dynamic fatigue endurance of rubber also increases compared to the standard composition and reaches 82,330 cycles. The properties of the vulcanizate, such as tensile strength, hardness and elasticity, do not change compared to the standard composition.

Example 8

This example is similar to example 2 with the difference that the modification of the rubber mixture and rubber based on high molecular weight nitrile butadiene rubber is carried out using low molecular weight unsaturated polyketone NP-BN-5.4 (oxygen content of 5.4 wt.%) Obtained according to Pat. RU No. 2230754 by oxygenation with nitrous oxide nitrile butadiene rubber BNKS-18A. This unsaturated polyketone contains units with carbonyl groups and units with nitrile groups and is a viscous oligomer with a molecular weight of M _n = 6300 (M _w / M _n = 2.3).

The modification is carried out by introducing into the rubber mixture 15 wt.% Of the specified unsaturated polyketone in relation to the total amount of high molecular weight rubber and low molecular weight polyketone. To do this, prepare a rubber mixture containing 60 g of unsaturated polyketone and 340 g of nitrile butadiene rubber. The content of the remaining components does not differ from the standard composition (table 4).

Modification of rubber according to the proposed method gives advantages compared with the elastomeric composition of a standard composition (table 11). The addition of a low molecular weight unsaturated polyketone leads to a significant increase in elongation (650%) and tear resistance (52 kN / m). Such properties of rubber as tensile strength, hardness, elasticity and frost resistance are practically unchanged.

Table 11.
Physico-mechanical characteristics of vulcanizates based on rubber BNKS Indicators Standard rubber Modified rubber with the addition of NP-PB-9.9 Elongation at break (%) 535 650 Tear resistance (kN / m) 38 52 Tensile Strength (MPa) 17.3 17.8 Shore hardness under normal conditions (conventional units) 59 60 Elasticity under normal conditions (%) 28 29th Frost resistance (° C) -52 -53

Claims (7)

1. The method of modification of rubber mixtures based on high molecular weight carbochain rubbers, as well as general and special purpose rubbers obtained by vulcanization of such mixtures, carried out by adding to the rubber mixture a low molecular weight polymer containing functional groups, characterized in that low molecular weight unsaturated polyketone is used for modification, containing carbonyl groups and carbon-carbon double bonds. 2. The method according to claim 1, characterized in that for the modification using a low molecular weight unsaturated polyketone obtained by oxygenation of nitrous oxide with high molecular weight polymers containing double carbon-carbon bonds. 3. The method according to any one of claim 2, characterized in that a low molecular weight unsaturated polyketone obtained by oxygenating nitrous oxide with butadiene, or isoprene, or butadiene-isoprene, or butadiene-nitrile rubbers is used for modification. 4. The method according to any one of claims 1 and 2, characterized in that from 0.5 to 50 wt.% Low molecular weight unsaturated polyketone relative to the total amount of high molecular weight carbochain rubber and low molecular weight unsaturated polyketone are added to the rubber mixture. 5. The method according to any one of claims 1 and 2, characterized in that for the modification using a low molecular weight unsaturated polyketone containing from 0.1 to 16 wt.% Oxygen in the form of carbonyl groups and having a number average molecular weight of from 500 to 100,000. 6. The method according to any one of claims 1 and 2, characterized in that for modification, a combination of low molecular weight unsaturated polyketones of different composition is added to the rubber mixture. 7. The method according to any one of claims 1 and 2, characterized in that low molecular weight unsaturated polyketones are used to modify the lining rubber composition in order to increase the bond strength of the lining rubber with tire cord and the dynamic fatigue endurance of the rubber.