HU185250B - Method for producing composition of controlled elasticity and hardness for purpose of microcellular or non-porous shoe-industrial soles - Google Patents

Abstract

The present invention relates to a method for producing a controlled elasticity and hardness composition for microcellular or solid shoe soles, which comprises, for microcellular sole, 20 to 45 wt.%, Preferably 31.95 wt.% Of rubber, 5-40 wt.%, Preferably 10.1 wt. % active filler, 0-40% by weight, preferably 32.95% by weight of inactive filler, 0.5-5% by weight, preferably 1.30% by weight of vulcanizing agent, 0.3-3.0% by weight, preferably 1.2% by weight % blowing agent, 5-40 wt.%, preferably 16 wt.% of polystyrene, caoutchouc, and atactic polypropylene blend, 0-10 wt.%, preferably 2.2 wt.% softener, 0.5-10 wt.%, preferably 4 wt. 25% by weight activator system; for solid soles - 20 to 45% by weight, preferably 41.0% by weight of rubber, 5-40% by weight of 18.4% by weight of active filler, 0 to 35% by weight, preferably 13.8% by weight of inactive filler, 0.5% -8% by weight, preferably 3.5% by weight of vulcanizing agent, 0-10% by weight, preferably 4.1% by weight of plasticizer, 5-40% by weight, preferably 16.0% by weight of reinforcing material consisting of polystyrene, rubber and atactic polypropylene , 0.5-10% by weight, preferably 3.6% by weight, of the activator system is mixed in a manner known per se. The reinforcing material mixture is 69.5-80% by weight, preferably 78.0% by weight of polystyrene, 10-21.7% by weight of the composition components, preferably 10.6% by weight of rubber, 8.7-10.7% by weight, preferably 10.7% by weight of atactic polypropylene. -1-

Description

FIELD OF THE INVENTION The present invention relates to a process for the manufacture of a composition with controlled elasticity and hardness for microcellular or solid footwear soles, comprising: natural and / or synthetic rubbers, fillers, vulcanizers, plasticizers, optionally foaming agents, polystyrene, rubbers, atactic polypropylene, activator system, in a manner known per se.

Many rubber-based products, such as shoe soles, require the material to have sufficient elasticity in addition to its elasticity. This is done by processing a mixture of rubber containing reinforcements into the soles.

Strengthening of rubbers with various resins, as is known, began with the reinforcement of natural rubbers with shell (The Venderbilt Rubber Handbook 1968).

In the 1930s, cyclized tires were used for this purpose.

Following the widespread industrial expansion of synthetic rubbers, a new type of resin, high styrene rubber, has been developed for this purpose (Whitby, GS Editor in Chief, Synthetic Rubber, 629-648; 1954; FH RoningerPrivate Communications-Uniroyal Chemical Division of Uniroyal, NC. Naugatuck, Conn. 8/7/67) Commercially available types eg POLYSAR SS 260, Duranit B, BUNA SB 115, Pliolite S 6. When using these materials, depending on the nature of the product to be manufactured, the reinforcing material is calculated to be 100 tr. It is used to reinforce natural rubbers and most synthetic rubbers, and its widespread use is mainly explained by its high reinforcing effect, and its main function is to increase hardness and tension with minimal alteration of other physical characteristics, and to apply it to hard rubbers. ge and tensile strength can be increased without increasing specific gravity or deteriorating flow properties of rubber mixtures. High styrene-containing rubber resins are capable of exerting their reinforcing effect by participating in the sulfur vulcanization process themselves. The disadvantage of the method used is that the use of this material results in a larger than allowed post shrinkage because the reinforcing material is also incorporated into the crosslinked structure. This disadvantageous property is e.g. it causes a major problem in the manufacture and use of high-precision footwear because the misaligned soles are unusable.

In addition, polyethylene (Dinzburg B.N., CNI I., I.B.I. Information Moscow 1968; Bryant C.K. Kautschuk und Gummi 15: 29-36 (1961); Susie A.G. Wold W.I. Rubber Age 65 537-540 (1979)) may be suitable for amplification purposes.

The use of polyethylene is known to be well miscible with natural butadiene, butyl rubber, but not miscible with butadiene acrylonitrile rubber. Polyethylene can only be used in a limited amount, since on the one hand the adhesive strength of the material is severely impaired (which, for example, inhibits the use of 2 in the shoe industry) and on larger quantities (above 25 tr) the physical mechanical properties (tensile strength) are significantly impaired.

The use of polystyrene in rubber mixtures is known. A disadvantage of processing with the use of polystyrene is that it is difficult to digest under normal conditions of rubber production. It requires a higher processing temperature and thus reduces the processing security of the system and the material can easily burn. Larger amounts make the product brittle and brittle.

It is an object of the present invention to overcome the drawbacks of the foregoing processes by providing a process whereby the amount of shrinkage of the rubber material, preferably in the manufacture of microcellular soles for the shoe industry, is kept within the permissible range. It is also intended to reduce the energy consumption of the rubber composition and to increase the processing safety of the material by providing a lower processing temperature. A further objective is the use of footwear soles The production of better soles, including the provision of adequate bonding strength, thereby improving the safety of use by improving the physical-mechanical characteristics necessary for the application of the product. Another important object of the present invention is to provide a solution which, in addition to the above-mentioned technical and application advantages, provides economic advantages over the previous ones.

The present invention is based on the surprising discovery that when a rubber composition comprising, in addition to the usual components, a specified proportion of a reinforcing material consisting of polystyrene, synthetic rubber and atactic polypropylene, the composition can be made with a microcell which has virtually no post-shrinkage and, without the use of blowing agent, a solid shoe sole which increases its strength and extends the life of both microcellular and solid shoe soles.

The present invention thus provides a process for the production of a controlled-elastic composition for microcell shoe soles from natural and / or synthetic rubbers, fillers, vulcanizers, plasticizers, blowing agents, reinforcing agents, activator systems such that 20-45% by weight, preferably 31.95% by weight of rubber. 40% by weight, preferably 10.15% by weight of active filler, 0-40% by weight, preferably 32.95% by weight of inactive filler, 0.5-5.0% by weight, preferably 1.3% by weight of vulcanizing agent, 0.3- 3.0% by weight, preferably 1.2% by weight of blowing agent, 5-40% by weight, preferably 16% by weight of a ^{0: 0} polystyrene, rubber and atactic polypropylene reinforcement blend, 0-10 'lmg / g, preferably 2.2% by weight plasticizer, 0.5 to 10% by weight, preferably 4.25% by weight of activator system is known per se.

By omitting the blowing agent, a solid shoe sole can be produced. In this case, we apply 20-45% by weight of rubber, preferably 41.0% by weight of rubber,

5-40% by weight, preferably 18.0% by weight of active filler-21

185 250, 0-35% by weight, preferably 13.8% by weight of inactive filler, 0.5-8% by weight, preferably 3.5% by weight of vulcanising agent, 0-10% by weight, preferably 4.1% by weight of plasticizer, -40% by weight, preferably 16% by weight, of a blend of polystyrene, rubber and atactic polypropylene, 0.5 to 10.0% by weight, preferably 3.6% by weight, of the activator system is known per se. The reinforcing mixture used for both microcellular and solid shoe soles is 69.5-80% by weight, preferably 78.7% by weight of polystyrene. containing about 10-21.7% by weight of atactic polypropylene, preferably 10.6% by weight, of rubber, 8.7-10.7% by weight, preferably 10.7% by weight.

Thus, the reinforcing mixture is composed of three components in a defined ratio.

The rubber component of the composition may be styrene butadiene rubber, natural rubber, polychloroprene, polybutadiene, polyisoprene, acrylonitrile rubber. The builder material for microcellular compositions may be e.g. azodicarbonamide, dinitrosopentamethylene tetramine, benzenesulfohydrazide (Evipor, Chempor). Generally, the accelerator system is guanidine derivatives and amide accelerators, benzylazole derivatives; or some combination of these is used. Fillers include e.g. soot, chalk, kaolin, etc. as plasticizer spindle oil, compressor oil, etc. to use.

Among the components of the reinforcing composition, the polystyrene component may be any commercially available polystyrene type (e.g., PSZM-115) or any type of impact-resistant polystyrene (eg, UPM-612 L). Any commercially available rubber (e.g. styrene-butadiene rubber, polybutadiene, polyisoprene, natural rubber) is suitable as a rubber component. The polypropylene component may conveniently be any atactic polypropylene type (APP H 601, 501, 301) which is a by-product of the production of isotactic polypropylene (e.g. Tisza Chemical Plant).

Of course, the components of the crude mixture influence the properties of the final product and also the mixing parameters and the vulcanization time, temperature and pressure parameters. Thus, depending on the type of material used, the mixing ratio, the range can be extremely wide.

The invention is further illustrated by the following non-limiting examples.

Example 7

Preparation of a composition suitable for microcell shoe soles (for street footwear)

For the composition, a reinforcement blend is prepared separately. (In our example, this is referred to as the "A" blend.) The amount of the "A" blend components (kg)

1. Polystyrene (UPM 612 L) 63

2. Styrene Butadiene Rubber '(SZKS7. 30 ARKPN Soviet) &'

3. / Atactic Polypropylene '' (Product II 601 TVK) ⁵ '

The reinforcing compound can be prepared in any rubber mixer (eg 80 l Forrei Bridge internal mixer). 63 kg of polystyrene and 8.5 kg of styrene-butadiene rubber were added to the mixer heated to 180 ° C. After stirring for 50 minutes at 50 rpm, 8.5 kg of atactic polypropylene is added. The mixtures were then stirred at 140 ° C for a further 2 minutes.

Mixtures of the reinforcement prepared as above are granulated with a coupled granulator.

The reinforcement mixture A is mixed with the other components of the composition (Table I) in a manner known per se to form a closed cell microporous rubber system for shoe use. Composition 1 comprises 16% by weight of a blend of reinforcing material A; 10% by weight and 111% by weight of blend A are mixed.

for comparison, compositions were also prepared using conventionally used high styrene high styrene butadiene rubber resin (Polysar-SS-260) (Composition IV). We also prepared a composition in which only polystyrene (V) was added as a reinforcement.

Table 7

Bemerendő type of material Quantity of substances to be measured (weight '') I II. 111th ARC. V I.SZKS'Z-30 ARKPN 27.60 33.60 16.00 27.60 27.60 2 “The strengthening mixture 16:00 10:00 40.00 - - 3 POLYSAR SS- 260 16.00 - 4 POLISZTI- ROL 16.00 c I'll call you full 40'1 ,,, 7:25 7.25 7.25 7.25 7.25 6 Sulfur 0.80 0.80 0.80 0.80 0.80 7 Chempor PC80 1:20 1.20 1:20 1.20 1.20 S Altax 0:25 0:25 0:25 0:25 0:25 9 OPG 0:25 0:25 0:25 0:25 0.25 10 Slenrin 2.25 2.25 2.25 2.25 2.25 II ZnO 2:00 2:00 2:00 2.00 2.00 12 Windsor is missing 17.25 17.25 10.00 17.25 17.25 13 Hocsch KS 404 7.25 7.25 - 7.25 7.25 14 l'ckele micro flour 15.70 15.70 10:00 15.70 15.70 15 spindle Oil 2.20 2.20 10.00 2.20 2.20 Altogether: | 100.00 100.00 I 100.0 100.0 100.0

The composition was made by mixing in a 120 L Commerio type internal mixer heated to 100 ° C. Mixer speed: 50 rpm. THE 2.

The table below shows the mixing order and typical mixing times for the cases examined:

Table 2

Mixing order I Mixing time / pcrc 11. III. ARC. V Commander 1: Synthetic rubber and reinforcing material 2 2 2 2 2 Step 2: Aging inhibitors, activators 2.5 2.5 2.5 2.5 2.5 accelerators Step 3: Filler Nut  gos, softeners 2.5 2.5 2.5 2.5 2.5

Table 3 shows the evolution of mixing temperature and energy consumption of mixing.

Table 3

Shuffle sign

I. II. III. ARC. V

Mixing temperature ('C) 100 100 100 100 100 departure ('C) end temperature (° C) 134 142 160 155 170 Power consumption (kWh) 10.6 11.7 15.5 15.2 170

Sulfur and buoyant mixing were carried out on a roller coaster in all three cases. The material thus obtained was vulcanized on a steam-heated etage press.

Vulcanization temperature 160 ° C

Cure time 10 minutes

From the data in Tables 2 and 3, it can be seen that there is a significant difference between the final blending temperature and the energy requirement of blending.

The final mixing temperatures of the composition according to the invention are as follows:

i. composition 21 'C in the formula II. The composition is 13 'C lower than that of the conventional method (IV)

In III. the mixing temperature of the composition is shown in FIG. and

Sun is between. The final temperature of composition V (purely polystyrene) is 15 ° C higher than that of the conventional method (composition IV).

Table 4

Physicomechanical indicators First II. Mixture sign III. ARC. V Breaking strength wormhole killed (N / ntnr) 3.4 3.9 3.2 3.5 3.0 Breaking strength after aging (N / mm ² ) 3.6 4.4 3.5 4.1 3.1 Elongation at break before thaw (%) 170 208 145 212 143 Elongation at break after aging (%) 165 207 143 220 138

Physicomechanical indicators Mixture sign I II. 111th ARC. V Tear strength 18 22 14.8 19 13.4 5 (N / mm) Remaining elongation (30% _ at t% elongation) 2.6 2.2 3.5 2.0 3.5 10 Linear Shrink ·? 1 7 ' ¹ sec THE % (%) German Hardness (DVM) Durable compression 70 70 60 70 65 the remaining figure caused by another- 8.5 8.5 9.8 9.3 9.0 15 change (%) Permanent folding- scarf resistance 25 kc / folding 25/0 25/0 Than 20 broken 25/0 13 Kc-nes dagger 20 after the bag Density (g / cm ') Peeling strength 0.54 0.53 0.54 0.53 0.55 (N / mm) (two -component polyurethane 3.8 3.7 3.5 3.2 3.7 25 leather glued soles)

Comparing the characteristics of the cellular material, the physical-mechanical properties of the samples measured from the samples are not unambiguously specific to the material. The most common indicator is the walking test. The results of the wear tests performed were as follows:

Table J.

I Mixture sign II. III. ARC. V 100 days average wear time after worn corner thickness (Mm) (30 30 pairs average value) 4 5 5 6 soles broken

The wear life of the sole produced from the composition obtained by the process of the invention is on average 1.5-1.8 times that of a conventional sole. Soles containing only polysilirol cannot be used because they are broken or cracked after a short wear.

This is due to the different morphological structure of the two materials. The microcell materials prepared according to our method have a more homogeneous cellular structure (finer average cell diameter) than the microcell material produced by the conventional method and are therefore more resistant to practical stress. This more homogeneous and finer cellular structure is formed by the fact that during the vulcanization of the composition of our proposed composition, the decomposition products (mainly N ₂ ) of the blowing agent are significantly more soluble than in the conventional reinforcing composition (IV) with the same processing parameters.

-4185 250

Example 2

Preparation of a composition suitable for microcellular soles (for special footwear).

No. 6 was prepared as described in Example 1.

Table 6 Type of material to be measured Quantity of substances to be measured (% by weight) 1. SZKSZ-30 ARKPN 42,70 2. Strengthening Compound A 16.00 3. Soot batsh 40% - 4. Ken 5. Chempor Pc / 80 6. Altax 7. DPG 8. Stearin 9. ZnO 10. Windsor kaolin 11. Hoesch 404 0.30 0.30 0.10 0.10 0.20 0.30 40.00 12. Black micro-meal 13. Spindle Oil - Altogether: 100.0

Physical-mechanical nightmares meet the requirements. The strength of the product is outstanding, but due to the slow vulcanization of the system, this process is not productive under industrial conditions. In addition, the product has a high density (0.7-0.8 g / cm ³ ). i

Example 3

Preparation of a composition suitable for a microcell sole (for house shoes).

No. 7 A mixture according to Table 1 was prepared. as described in Example.

Table 7 Type of material to be measured Quantity of substances to be measured (weight ',' ;,) 1. SZKSZ-30 ARKPN 17,00 2. Strengthening Compound A 10.00 3. Sulfur 3.00 4. Chempor PC / 80 3.00 5. Allax 1.00 6. DPG 1.00 7. Stearin 3:00 8. ZnO 7.00 9. Windsor kaolin 20.00 10. Hoesch 404 5.00 11. Black micro-meal 20.00 12. Spindle oil 10.00 Altogether: 100.00

Based on physical-mechanical amusements, this product, due to its low density (0.3-0.4 g / cm ³ ), is mainly used for making home shoes and beach shoes.

Example 4

Preparation of a composition suitable for solid footwear (for street footwear).

In this case, the reinforcement mixture is prepared separately. (In our example, we call it "B" or "C" reinforcement blend.) The amount of "B" pre-blend reinforcement ingredients

1. About Impact Resistant Polis (IJPM-6I2 L Soviet)

2. Slirol Butadiene Rubber (SZKSZ-30 ARKPN Soviet)

3. Atactic polypropylene (product H 601 TVK)

The method of preparation of the "B" reinforcement mixture has the same parameters as the "A" mixture, except that the mixture is blended in a 120 L Comerio internal mixer.

To the mixer, which had risen to 180 ° C, 80 kg of impact-resistant polystyrene and 25 kg of styrene-butadiene rubber were homogenized for 3 minutes at 50 rpm, then 10 kg of atactic polypropylene was added. The mixture was then stirred at 140 for 2 minutes .

,, Amount of C Blend Components

1. Impact-resistant polystyrene (UPM-612) 40 kg

2. Styrene Butadiene Rubber _s , ISKS7.) - 30 ARKPN) ' ^g

3. Atactic polypropylene.

4! 601 TVK termek) ^{p 8}

Mixtures of reinforcement "C" 50 l Parte! It was made in a Btidge internal mixer. 40 kg of polystyrene and 5 kg of styrene-butadiene rubber were added to the internal mixer heated to 180 ° C. After stirring for 50 minutes at 50 rpm, 8.5 kg of atactic polypropylene was added. The reinforcing mixture was then stirred at Ϊ () 'C for a further 2 minutes.

With the other components of the solid-base composition (Table 8), Example 1 is a mixture of A and a mixture of reinforcing agents B and C as described above in Table 8. The compounds of Table II are mixed in a manner known per se (Composition VI, VII, VIII). IX. Composition A contains 5.0% by weight of the "A" blend composition ", -. By way of comparison, we have prepared a blend of conventionally used strengthener (l'OLYSAR SS-260) (blend X),

Table 8

Mix ingredients name Measurable quantity loess' ^, / -b: iu VI. VII. viii. IX. X. i.SZKSZ 30 ARKPN 2. “The strengthening mixture 32,50 16:00 32,50 32,50 43.00 30.50 5.00

s

-5185 250

Mix összelevők name Quantity to be measured in% by weight VI. VII. VIII. IX. X. 3. Strengthening Compound B 4. C Strengthening Compound 5. POLYSAR SS260 6. Reclaimed rubber 7. CKS Ken 95% 8. Thiuram 9. Denax 10. Sulphenax CB .130 11. ZnO 12. ZKZ kaolin 13. Suprasil 14. Compressor oil 15. Stearin 8:50 1.30 '0.20 0.50 1:50 2.00 13.80 18,00 4.10 1.60 16.00 8:50 1.30 0.20 0.50 1:50 2.00 13.80 18,00 4.10 1.60 16.00 8:50 1.30 0.20 0.50 1:50 2.00 13.80 18,00 4.10 1.60 2.40 1.30 0.20 0.50 1.50 2.00 13.80 18,00 1.60 16.00 8:50 1.30 0.20 0.50 1:50 2.00 13.80 18,00 4.10 1.60 Altogether: 100.0 100.0 100.0 100.0 100.0

In all cases, the final temperature of the mixing is reduced compared to the conventional process (Table 10). Thus, the use of the composition of the proposed composition significantly improves processing safety (reduces the risk of burns). All. Table III compares the physical characteristics of solid rubber sheets made from the compositions of the present invention (VI, VII, VIII, IX). They meet the requirements of the standard and have better wear and strength properties than the conventional process (X.).

Table 11

The composition was prepared by mixing in a Comerio-type internal mixer, which was heated to 100 ° C. The agitator speed is 50 rpm. Table 9 shows the mixing order and typical mixing times for the two cases.

Table 9

Mixing time (minutes)

VII. Vili. IX.

Mixing order

VI.

X.

Step 1: Synthetic rubbers and 3 3 3 3 3 reinforcing materials Step 2: Aging inhibitors, activators, 3 3 3 3 3 accelerators Step 3: Charging materials, plasticizers 3 3 3 3 3

Physicomechanical indicators Composition sign VI. VII. VIII. IX. X. Hardness (Sh A) 96 96 96 91 95 Breaking strength (N / mnr) 10.7 10.0 9.6 8.9 9.3 before aging Baccalaureate strength after aging 9.2 9.0 8.5 8.5 8 (N / mmj Elongation at break) before aging Elongation after aging 261 272 260 300 250 219 257 250 272 220 '' 11 1 Density (g / mm ') 1.26 L24 1.25 1.29 1.25 Wear (mm ') 500 . 522 530 516 550 Permanent elongation (%) 6 6 6 4 6 Breaking strength (N / 55.5 54.5 54.5 53.0 53.0 mm) Folding 25/0 25/0 25/0 25/0 25 / Ό Peeling strength (N / mm) (fine component 4.8 4.5 4.6 4.6 4.5 bonded with polyurelane glue)

Table 10 shows the evolution of mixing temperature and uptake of mixing energy.

Table 10 45

Example 5

Mixing order

VI.

Mixture symbol VII. Vili. IX.

A solid soles composition (for heavy-duty footwear).

The mixture of Table 12 is prepared with the mixing parameters described in Example 4, Example 4. Amplifier A included in the mixture

Mixing temperature ('C) start (' C) end temperature ('C) power consumption (kWn)

100

148

13.1

100 100 100 100 155 150 150 -175 15.0 14.2 12.6 19

The sulfur was blended in a roller in all cases. The material thus obtained was vulcanized on a steam-heated etage press. Vulcanization parameters:

vulcanization temperature; 160 ° C vulcanization time: 10 minutes

It can be seen that there is a significant difference between the blending end temperature and the energy requirement of blending for each blend. Using the process of the present invention, the energy required for mixing and the

The preparation of the mixture is described in Example 1. ⁵⁰ Table 12 Type of material to be measured Quantity of substances to be measured (% by weight) 1. S7.KSZ-30 ARKPN 55 2. “The Amplifier Mixes 3. Reclaimed rubber 4. CKS Sulfur 951 /, - 05 5. Thiuram 6. Denax 7. Stilfenax CB-130 60 8- ZnO 9. ZKZ kaolin 10. Suprasil 11. Compressed oil 12. Slearin 23.00 16.00 15.00 0.30 0.10 0.10 0.30 5.00 40.00 0.20 Altogether: 65 100.00

185,250

The physical characteristics of the product thus obtained are satisfactory. Particularly high values were obtained for tear and tear strength. However, due to the long vulcanization times, the process is not productive on an industrial scale.

Example 6

A composition suitable for a solid sole (for household use). |

No. 13. A mixture according to Table 4 was prepared. with the mixing parameters described in Ex. The method of preparation of the reinforcing mixture "A" in the mixture is described in FIG. embodiment.

Table 13

Type of material to be measured Quantity of substances to be measured (mass /) 1. SZKSZ-30 ARKPN 10.00 2. Strengthening Compound A 16.00 3. Reclaimed rubber 6.00 4. CKS sulfur 95% 3.50 5. Thiuram - 6. Denax 2.50 7. Sulfenax CB-130 1.70 8. ZnO 7.00 9. ZKZ kaolin 35.00 10. Suprasil 5.00 11. Compressor oil 10.00 12. Stearin 3.00 Altogether: 100.00

The physical characteristics of the product according to the process are satisfactory. It is mainly suitable for making home boots.

Claims (2)

A process for making a composition of controlled elasticity and hardness in the microcell shoe industry 5 soles of natural and / or synthetic rubbers, fillers, vulcanizers, blowing agents, reinforcing agents, plasticizers, activator systems, characterized in that 20-45% by weight, preferably 31.95% by weight of rubber, 5-40. 10% by weight, preferably 10-15% by weight of active filler, 0-40% by weight, preferably 32.95% by weight of inactive filler, 0.5-5.0% by weight, preferably 1.3% by weight of vulcaniser 0.3 to 3.0% by weight, preferably 1.2% by weight of foaming agent, 5 to 40% by weight, preferably 16% by weight - to 69.5 to 80.0% by weight of polystyrene, 10 to 21 , 7 wt.% Of rubber and 8.7-10.7 wt.% Of a mixture of atactic polypropylene reinforcing material, 0-10 wt.%, Preferably 2.2 wt. //, preferably 4.25 wt% activator system is mixed in a manner known per se. 2. A process for making a composition of controlled elasticity and hardness for use in a solid footwear sole from natural and / or synthetic rubber, 25 fillers, vulcanizers, plasticizers, reinforcing agents, activator systems, characterized in that 20 to 45% by weight, preferably 41.0% by weight of rubber, 5 to 40% by weight, preferably 18.0% by weight of active filler, 0 to 35% by weight //, preferably 13.8% by weight of inactive filler, 0.5-8% by weight, preferably 3.5% by weight of vulcanizing agent, 0-10% by weight //, preferably 4.1% by weight of plasticizer, 5- 40% by weight, preferably 16% by weight, - 69.5-80% by weight of polystyrene, 10-21.7% by weight of rubber and 8.7 to 10.7% by weight of a mixture of atactic polypropylene reinforcing agents is mixed with 0.5 to 10% by weight, preferably 3.6% by weight, of the activator system in a manner known per se. Without illustration