DE1570149A1 - Process for vulcanizing blends of cis-1,4-polybutadiene and oil-expanded butadiene-styrene rubber - Google Patents

Description

Process for vulcanizing blends of cis-1,4-polybutadiene and oil extended butadiene-styrene rubber. The invention relates to a method for vulcanizing blends of cis-i, 4-polybutadiene and oil-extended Butadiene-styrene rubber, especially for vehicle tires or the like, with the usual, Zinc oxide, plasticizers, soot and anti-aging agents including additives, under pressure and heat.

Made from blends of cis-1,4-polybutadiene and oil-extended butadiene-styrene rubber built-up treads of vehicle tires have good properties except for slip resistance, which should be better. This deficiency is already remedied by the addition a lot of plasticizer and a lot of carbon black or filler have been tried.

However, this tends to deteriorate the abrasion resistance of the vulcanizate and the related advantage of the cis-1,4-polybutadiene also then in Asked if its proportion in the waste is kept low.

The general properties of a tire tread made from an im Ratio 1: 1 kept blend of cis-1,4-polybutadiene and oil-extended Butadiene-styrene rubber are better than those of a tread whose rubber content consists entirely or to a substantial extent of butadiene-styrene rubber. Of the only disadvantage of such a cis-1,4-polybutadiene-butadiene-styrene-rubber blend consists in the tendency of the tire tread to slip at a temperature between about 200 to 300 C on a wet road. Oil-extended butadiene-styrene rubber only Vulcanizates containing them, on the other hand, have the best coefficient of friction, especially on wet roads.

The coefficient of friction that determines the slip resistance of a rubber vulcanizate depends next to the important polymer configuration and the surface finish of the tire tread on the values of the module 300, the Shore hardness, the elongation at break and elasticity together.

Appropriate polymer configurations have so far been available to manufacturers of rubber polymers are not obtained and are therefore available for the production of rubber vulcanizates for tire treads with the properties required for them are not available. In addition to the static properties of a rubber blended bulk, especially of the type mentioned above, are also its dynamic properties to be observed. The dynamic properties (dynamic module E ') of the vulcanizate a mixture can be related to its intrinsic viscosity Elt.

This results in the damping factor Q = E "/ E '# Is the inner one Viscosity E "is high, so heat is developed in the vulcanizate, while a high viscosity is more dynamic Module E 'promises better tire stability. The developed in the vulcanizate Heat. Is insignificant if the vulcanizate is also heat-resistant. A high one Attenuation factor Q suggests favorable slip resistance. So if it succeeds then keeping the intrinsic viscosity E "high and the dynamic modulus E 'low a good slip resistance of the vulcanizate can be achieved.

The dynamic module E 'can also be influenced by the selection of the polymer as this depends mainly on the polymer characteristics of the vulcanizate.

Fillers, plasticizers and vulcanization systems have to size of the dynamic module also influence. Butyl rubber has z. B. a high inner Viscosity En and a low dynamic modulus E '. Butadiene-styrene rubber has a higher dynamic modulus than butyl rubber.

In contrast, cis-1,4-polybutadiene has a low intrinsic viscosity and a high dynamic modulus.

The intrinsic viscosity (Mooney viscosity) of different raw rubbers has the following values: CisI, 4-polybutadiene 40-50, oil-extended butadi [n-styrene rubber 45 - 60, chlorobutyl rubber 60 - 70, butyl rubber (Butyl 218) 70 - 80.

After it was recognized that a higher viscosity E11 due to high filler and plasticizer proportions of the rubber blends indicated above and / or by As yet unachievable rubber polymers can be achieved, it has been found that an advantageous balance between inadequate rubber polymers and / or the sometimes negative influence of high fillers and plasticizers when such rubber compounds are vulcanized, the chlorobutyl rubber or halogenated butyl rubber, zinc stearate, Silica, mercaptobenzimidazole, at most 1.3 parts by weight of elemental sulfur, based on 100 parts by weight Total rubber, dibenzothiazyl disulfide, mercaptobenzothiazole, tetramethylthiuram disulfide, pp '-dibenzoylquinone dioxime and phthalic anhydride as a vulcanization system. According to a further concept of the invention, the proportion of silica within a constant amount of total filler (carbon black and silica) up to 20 parts by weight, based on 100 parts by weight of total rubber. Finally, 10 can up to 20 parts by weight of chlorobutyl rubber, based on 100 parts by weight of total rubber, can be added.

Instead of chlorobutyl rubber or halogenated butyl rubber can with a certain, still advantageous change in the properties of the vulcanizate butyl rubber can also be added to the blending mixture which forms the vulcanizate. The surface of a used tire shows when the tire tread compound Butyl rubber contains a significant amount compared to that made with normal polymers Difference on. Tire treads with butyl rubber behave on wet roads The surface of the tire tread becomes very good with a small addition of butyl rubber rougher.

Below is known mixtures I, II and the properties of vulcanizates from these a mixture III according to the invention with the properties juxtaposed with their vulcanizates.

Mixture I parts by weight of oil-extended butadiene-styrene rubber 123.8 (= Trade name Synpol 17121 137.5 parts Synpol 1712 = 100 parts rubber + 37.5 Parts 01) butadiene styrene rubber (Buna S4) 10 plasticizers (Naftolen) 10.8 glue (Coumarone resin, liquid) 4.7 zinc oxide (zinc I RS) 3 stearic acid (stearin P) 2 glue (Resin Col) 2 N-phenyl-N'-isopropyl-p-phenylenediamine 0.75 (Aldol 4010 NA) phenylbetanaphthylamine (Aldol beta Sch) 0.75 Zinc salt of pentachlorothiophenol 0.2 (Renazit IV gran.) Highly abrasion resistant Furnace black (Corax 3) 81 oil sulfur 0.2 110 parts oil sulfur = 100 parts 1.1 sulfur + 10 parts oil oil sulfur Chrystex; 20 parts of oil sulfur = 100 1.2 parts of sulfur + 20 parts of oil N-cyclohexyl-2-benzothiazolesulfenamide with oil 1.56 (Olvulkazit CZ) Dibenzothiazyl disulfide with oil (oil volkacite M; 0.66 130 parts oil volcacite M = 100 parts Vulkazit M + 30 parts oil) Test results: Heating at 143 ° C 45 min 60 min module at 300% (kg / cm22) 79 81 module at 500% (kg / cm) 153 148 tensile strength (kg / cm2) 159 158 Elongation at break (%) 540 515 Shore hardness (° A) 50 54 Elasticity (%) 28 27 Aging three days at 1000 C heating at 143 ° c 45 min 60 min module at 300% (kg / cm22) 145 i32 module at 500%% (kg / cm22) tensile strength (kg / cm) 150 150 elongation at break (%) 310 335 Shore hardness (° A) 56 56 Elasticity (X) 24 25 Mixture II parts by weight Cis-1,4-polyubutadiene (Buna Hüls CB) 50 butadiene-styrene rubber (Buna S4) 10 oil-extended Butadiene-styrene rubber 55 (Synpol 1712) N-methyl-N-4-dinitrosoaniline + 33 X kaolin 0.2 (Elastopr) plasticizer (naftolen) 21.8 zinc oxide (zinc I RS) 3 wax (ozokerite P) 3 stearic acid (stearin P) 2 glue (coumarone resin, liquid) 2 N-phenyl-N'-isopropyl-p-phenylenediamine 1.5 (Aldol 4010 NA) Phenylbetanaphthylamine (Aldol beta Sch) 1 Very highly abrasion-resistant Furnace black (Corax 6) 75 Oil sulfur 0.2 2.2 N-cyclohexyl-2-benzothiazolesulflenamide with 01 1,2 (oil volkacite CZ; 120 parts oil volkacite CZ = lQO parts vulkacite CZ + 20 parts Oil) Tetramethylthiruammonosulfid (Vulkazit Th MS) 0.1 Test results: Heating at 1430 C 45 min 60 Elin module at 300% (kg / cm22) 66 68 module at 500% (kg / cm2) 135 140 Tensile strength (kg / c)) 140 148 Elongation at break (%) 510 510 Shore hardness (° A) 58 58 elasticity (%) 32 31 Aging for three days at 1000 C heating 1430 C 45 min 60 min module at 300% (kg / cm2) module at 500 5 (kg / cmi tensile strength (kg / cm) 125 133 Elongation at break (5 ') 285 295 Shore hardness (° A). 67 67 elasticity (5 ') 35 33 Mixture III parts by weight of cis-1,4-polybutadiene (Buna Hüls CB) 40 oil-extended Butadiene-styrene rubber 68.8 (Synpol 1712) chlorobutyl rubber (chlorobutyl HT 10-66) 10 plasticizers (naftolen) 30 zinc oxide (zinc I RS) 1.5 zinc stearate 3.5 wax (Ozokerite P) 3 N-phenyl-N'-isopropyl-p-phenylenediamine 0.75 (Aldol 4010 NA) 2-mercaptobenzimidazole (MB) 0.75 Adhesive (coumarone resin, liquid) 1 Silicic acid (VN 3) 4 Very highly abrasion-resistant Furnace black (Corax 6) 76 Phthalic anhydride (Vulkalent B) 1.5 Oil sulfur 0.2 1.1 2-mercaptobenzothiazole (Vulkazit C) 0.5 tetramethylthiuram disulfide (Vulkazit Th) 0.1 dibenzothiazyl disulfide with oil (Olvulkazit M) 2.6 pp'-dibenzoylquinone dioxime (Dibenzo GMF) 1.5 The portion of silica can be up to 20 parts by weight, if the proportion of the total filler the mixture remains the same.

Test results: heating at 1430 C 45 min 60 min module at 300% (kg / cm2) 58 61 Module at 500% (kg / cm2) 111 114 Tensile strength (kg / cm) 122 123 Elongation at break (5 ') 545 530 Shore hardness (° A) 60 60 Elasticity (5') 30 31 Notch toughness (kg / cm) 24 24 Pull-out strength (kg / cm) 61 61 Aging for three days at 100 ° C heating 1430 C 45 min 60 min module at 300% (kg / cm2) 87 85 module at 500 5 '(kg / cm22) tensile strength (kg / cm2) 106 114 Elongation at break (5 ') 360 400 Shore hardness (oA) 67 67 Elasticity (%) 34 34 Notch toughness (kg / cm) 21 23 Pull-out strength (kg / cm) 63 65 In the present Mixture III used chlorobutyl rubber because it is halogenated by all Butyl rubbers are the cheapest with the same properties.

Mixture I was cited because it was essentially 100% butadiene-styrene rubber containing treads have the best coefficient of friction on wet roads. In contrast, the mixture III, although it contains cis-1,4-polybutadiene, values almost as good as tire treads made from vulcanizates of this mixture still have satisfactory properties. Through practical Driving tests with tires that had treads with vulcanizates of mixtures I to III found that the slip resistance of the vulcanizate of mixture III was better than that of the vulcanizate of mixture II and as good as that of the vulcanizate of Mix I is. The test results for mixture III show better aging properties than that of Mixtures I and II. Mixture III also conveys something lower elasticity than mixture II. This increases the damping factor Q.

The dynamic modulus is lower for Mix III.

The chlorobutyl rubber content can be per 100 parts by weight of rubber 10 to 20 parts by weight. Since the chlorobutyl rubber is very expensive, it should its mixing ratio is kept as low as possible for the respective purpose if value is placed on cheap vulcanizates without deterioration in quality will.

The table below shows examples that have been established through experiments Slip resistance (coefficient of friction 1.0 m / s) for mixtures I to III. unaged aged mixture 0 ° C 30 ° C 0 ° C 300 C 1 0.863 0.595 0.839 0.620 II o, 44o 0.449 0.461 0.359 III 0.459 0.496 0.491 0.387 As known test methods for determining the coefficient of friction of a rubber vulcanizate are unreliable the above-mentioned coefficients of friction and the associated slip resistance found in practical driving tests.

Claims (3)

Claims 1. A method for vulcanizing blends of cis-1,4-polybutadiene and oil-extended butadiene-styrene rubber, in particular For vehicle tires or the like, pnit in addition to the usual, carbon black, zinc oxide, plasticizers and Anti-aging agents, additives, under pressure and heat, characterized in that such rubber mixtures are vulcanized which Chlorobutyl rubber, zinc stearate, silica, no more than 1.3 parts by weight of elemental Sulfur, based on 100 parts by weight of total rubber, mercaptobenzothiazole, tetramethylthiuram disulfide, Dibenzothiazyl disulfide, pp'-dibenzoylquinone dioxime, mercaptobenzimidazole and phthalic anhydride contain. 2. The method according to claim 1, characterized by a proportion of freezing acid within a constant amount of total filler (carbon black and silica) up to 20 parts by weight, based on 100 parts by weight of total rubber. 3. The method according to claim 1 or 2, characterized by about 10 up to 20 parts by weight of chlorobutyl rubber, based on 100 parts by weight of total rubber c.