DE1906037A1 - Treads for the production of the treads of passenger car tires based on homopolymers of butadiene - Google Patents

Description

! strip for the production of the treads of pneumatic tires based on Homopolymers of butadiene

The present invention relates to treads for the production of treads based on pneumatic tires for passenger cars of homopolymers of butadiene and a process for the production of these treads.

It is known that the treads of pneumatic passenger car tires consist of vulcanizates filled with large amounts of oil and soot Rubber cut. Up to now, blends made from emulsion or solution polymerization have been used as rubber blends produced on copolymers of butadiene and Styrene with stereoregular polydiolefins, preferably cis-1,4-polybutadiene. The cutting ratio usually fluctuates between 80:20 and 50:50. If the proportion of stereospecific polydiolefins is increased, this increases the mileage of the tire, in the same sense, however, the slip resistance of the barrel is impaired. From this fact it inevitably follows a compromise between the aforementioned properties for the practice of tire manufacture.

The exclusive use of the previously known homopolybutadienes stood next to the mentioned inadequate adhesion of tire treads made from it on wet roads also the Kaohtell unreasonable processing inheritance

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opposite. To achieve optimal combinations of properties one saw in the absence of suitable polymers that combine the above-mentioned favorable compromise, forced to fall back on the mentioned -cuts again and again and at the same time adapting the composition of the blends to the respective requirements. The usage of However, blends require more cost-effective manufacturing conditions. There are also difficulties the often difficult to achieve homogeneous distributions of the used, in their chemical constitution various waste components result.

It therefore existed in view of the rather complex production of these blends a great economic interest in finding new polymers that meet all requirements within the scope of the usual compromises described in more detail above in the overall property profile of the vulcanizates meet, but essential technical and especially economical in their production and processing Offer advantages.

There has therefore been no lack of attempts to find all possible polymers - including homopolymers of different butadiene Structure - to be examined for their possible uses. As part of these investigations, one has already found j that not only homopolymers of diolefins with high levels of 1,4-cis structure, especially 1,4-cis-polybutadiene, but also homopolymers with very low (below 10 ^) or very high (over 50 #) contents on monomer units arranged in the 1,2-position in have somewhat useful elastomeric properties. E.W. Duck and J.M. locke (Jour. I.R.I. £ (1968), page 223) found that polybutadiene with contents in 1,2-position arranged monomer units of

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more than 50 fo no "cold plow" and higher manufacturing tack than other polymers and, moreover, have absolutely useful rubber-technological properties. However, these polybutadienes with a content of monomer units in the 1,2-position of more than $ 50 show an abrasion resistance which is clearly inferior to that of the standard SBR types and even more blends of SBR with 1,4-cis-polybutadiene .

It has now been found that the disadvantages shown in Surprisingly and economically advantageous ways can be avoided when using treads for manufacture of the treads of passenger car pneumatic tires based on homopolybutadiene, which are made from

(A) a polybutadiene with a content of monomer units arranged in the 1,2-position of 25 to 50 $, preferably 30 to 45 ft, of 1,4-cis double bonds of 10 to 40 $, of 1,4- trans double bonds from $ 15 to $ 55 and an ML-4 value from 40 to 120;

(b) from 5 to 100 parts by weight of a plasticizer based on 100 parts by weight of polybutadiene;

(c) from 30 to 120 parts by weight of a carbon black, based on 100 parts by weight of polybutadiene,

exist.

According to a particularly advantageous embodiment According to the present invention, the treads are based on polybutadiene-plasticizer-filler mixtures Car tires from components (a), (b) and (c) and as an additional component (d) from a vulcanization system, the 1 to 3 parts by weight of sulfur and 0.5 to 2.5 parts by weight MercaptobenzotMazol or its derivatives, especially its sulfenamides.

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With the use of the tire treads produced in this way based on stereoregular homopolybutadiene with a content of. 25 to 50 fo _t preferably 30 to 45 ° f * ati in the 1,2-position arranged monomer units a particularly urgent technical need is - namely, the susceptibility to faults in the production of today usual waste mixtures to avoid - met.

These polybutadienes used according to the invention in a mixture with high amounts of plasticizers and carbon black allow a high proportion of polybutadienes compared to conventional polybutadienes in the 1,4-position arranged monomer units considerably improved processability and lead to treads with favorable sliding properties on wet roads with the usual requirements for pneumatic tires for passenger cars rubber technological properties.

The preparation of the polybutadiene according to the invention and used with contents of which is arranged in the 1,2-position monomer units of 25 to 50 $> is carried out in organic solvents with the aid of organolithium compounds with the addition of ethers of certain composition.

Lithiumn-butyl, for example, are used as lithium compounds, Lithium isobutyl, lithium methyl, lithium phenyl into consideration.

Suitable ethers are compounds of the general formulas ROR ¹ , ROR or "R'-0-RO-R ', R" -OROR ", in which R, R ¹ , R" (cycloaliphatic radicals with 1 to 20 carbon atoms and are aromatic radicals with 6 to 14 carbon atoms. Particularly suitable are dimethyl ether, diethyl ether, diphenyl ether, tetrahydrofuran, dioran, 1,2-dimethoxymethane, 1,2-dimethoxyethane.
The polymerization is carried out in the presence of aliphatic solvents

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solvents such as hexane and cyclohexane, preferably hexane, and aromatic solvents such as benzene and toluene, preferably benzene, made. The polybutadienes obtained in this way have, in addition to the content of monomer units arranged in the 1,2-position, 10 to 40 % 1,4-cis and 15 to 55 % 1,4-trans double bonds. Another advantage of the polybutadienes used according to the invention is the possibility of using larger amounts of plasticizer and carbon black. All aliphatic or aromatic oils customary in rubber processing can be used as plasticizers. They are used in amounts of from 5 to 100 parts by weight, preferably from 40 to 70 parts by weight, based on 100 parts by weight of polybutadiene. Highly active types of carbon black, such as HAP, ISAF, SAP - also in combination with light-colored fillers - come into consideration as fillers. They are used in amounts of from 30 to 120 parts by weight, in particular from 70 to 100 parts by weight, based on 100 parts by weight of polybutadiene. The amounts of filler and plasticizer must always be reasonably matched to one another. Good processing properties always result from a filler / plasticizer ratio of 1: 1 to 10: 1.

To produce the tire treads, the polybutadienes used according to the invention are added in the required quantities of plasticizer or oil mixed homogeneously using methods known per se under conditions that are as gentle as possible, then in again known methods and devices after the addition of customary rubber auxiliaries to tire treads extruded and then strip them on together with the Tire elements commonly used in tire construction, such as sidewalls and Carcasses, vulcanized in also known presses.

According to a particular embodiment of the present invention, one starts from a polybutadiene with a

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Content of monomer units arranged in the 1-, "2-position ^{: lii} from 25 to 50 fo _f preferably 30 to 45 f ^a t and puts" ^-ϊ · this polymer following the polymerisation before further processing on treads for the purpose the ■:,; . Molecular weight increase with catalyst systems made of, for example, active hydrogen-containing or proton-active compounds in combination with organoaluminum. Connection gen around. The work of Ε.Έ ¹ . Engel, J. Schäfer and KM Kiepert in "Rubber and Plastics Age" 45 (1964), page 1499 ff.

In addition to the increase in molecular weight due to the "jump in molecular weight" in the presence of these catalyst systems can also with advantage of the so-called "coupling reaction" of lithium polymers in the presence of compounds such as e.g. Methylene chloride, chloroform, particularly silicon tetrahalides, and carbon tetrachloride, use can be made (See U.S. Patent 3,244,664). In addition, there are other methods of increasing molecular weight, such as, for example, under Use of sulfur halides, especially disulfur dichloride, possible with equal success (DAS 1 260 794).

The 1,2-polybutadiene should have an ML-4 value of 10 to 60 have, which then under the conditions of the above-mentioned method for increasing the molecular weight to 70 to 120 can be increased. For the optimal effect to be achieved according to the invention, it is immaterial in certain cases whether the increase in molecular weight is present or absent the additives takes place.

As a further advantageous embodiment of the present invention, a vulcanization system is used which consists of 1 to 3 parts by weight of sulfur and 0.5 to 2.5 parts by weight of meroaptobenzothiazole or its derivatives, in particular its sulfenamides «
In addition, basic second accelerators can be used,

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The invention is based on the following exemplary embodiments explained in more detail:

example 1

A (based on butadiene) in the presence of lithium butyl in benzene with addition of 1% prepared diethyl ether * butadiene polymer after reaching a Mooney Yiskosität (ML-4100 ⁰ C) of about 40 with 1/4 equivalent, based on Lithium butyl, silicon tetrachloride added. Each time the Mooney viscosity is increased to 90 as a result of the "coupling reaction" taking place, the polymerization reaction is stopped as usual with methanol. The polymer present in solution has the following microstructure:

Arrangement of the monomer units

1,4-trans

1,4-cis

24

1.2

29

This is followed by the addition of 37.5 parts by weight of a plasticizer with a high aromatic content. The subsequent work-up of the polymer takes place by separating off the solvent with steam, dewatering by treatment in screw presses and dryers.

In the course of further processing, the help The following mixture is produced using an internal mixer:

oil rubber

Stearic acid

zinc oxide HAP soot

Coumarone resin

aromatic emollient oil üh.enyl-ß-naphthylamine

137.5 parts 2.5 parts 4.0 parts 70.0 parts 3.0 parts 2.5 parts 1.0 part

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Subject. 6-day storage "Btei room temperature are mixed in on a rolling mill at 50 ^{0 G:}

Sc & wefel 2 _r 2nd! Hurry

Mereaptobenzthiazolesulfenamid 1j2 parts

To determine the physisheTa. Data is achfilled one step (15t 50 * SO and SO Klniiten) at 14-3 ⁰ C with the following result s

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Heating time minutes

Strength ρ kg / cm

strain module hardness $ 300> ° Shore 412 67 59 396 84 59 420 ■ 98 61 408 96 60

Rebound elasticity

⁰ C

⁰ C

Abrasion Pico DIF 27 115 25th 98 25th 95 25th 96

Skid resistance concrete wet

135 144 138 132

52
53
52
52

44

44

Under the conditions of the same vulcanization recipe, a blend of OE-BR and OE-SBR in a ratio of 50:50 achieves the following result:

15 ' 164 390 70 60 35 51 120 27 45 30 »* 183 374 98 60 34 52 105 .26 45 60 » 174 398 104 61 35 52 100 26th 46 90 » 170 401 97 60 35 50 102 27 43

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Me unvulcanized mixtures are then treated with TTiIf e a suitable spraying machine to strip '"Deforms V'die

again for the production of a car tire of the dimension

6.40 - 13 serve. The vulcanization takes place in a tire heater for 30 minutes at 165 ^° C.; ·;

On a driving distance of about 10 km the resistance, the I / aufflächen against die_ wear under practical conditions determined. ...

In comparison to the tread from the cut OE-BR / OE-SBR = 50/50 shows the polybutadiene tread with a proportion of monomer units arranged in the 1,2-position from $ 29 the following result:

Abrasion index

Treads from scrap, OE-BR / OE-SBR = 50/50 = 100

Treads made of oil-extended polybutadiene with a 29 / f 1,2 proportion = 104

This makes the equivalence of the economically easier and homopolybutadiene to be processed more smoothly demonstrated the molecular structure described.

Example 2

A polybutadiene prepared according to Example 1, but using hexane as the solvent and 1 $> tetrahydrofuran instead of diethyl ether, after reaching a Mooney viscosity of 40 and adding 37.5 parts of oil with a high aromatic content (based on polymer) with 0 , 5 $> Disulfur dichloride (based on polymer) was added and treated in the original solution until a Mooney value of 40 was reached for the rubber-oil mixture.

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After removing the solvent with the help of steam, Pressing and drying the crumbs results in a gel-free polymer with the following microstructure:

Arrangement of the monomer units

1,4-trans

1,4-cis

1.2

39 9έ 23 #

The further processing to tire treads takes place analogously to the following vulcanization recipe:

Oil rubber coumarone resin zinc oxide stearic acid Phenyl-B-naphthylamine ISAF carbon black aromatic plasticizer oil sulfur mercaptobenzothiazole sulfenamide

137.5 parts

3.0 parts

.3.0 parts

2.0 parts

1.5 parts

85.0 parts

15.0 parts

1.5 parts

2.0 parts

To determine the physical data, step heating is carried out at 151 ^° C (10, 20, 30, 40 minutes) with the following result:

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Heating time Firm strain module hardness Rebound ' 22 ⁰ O 28 75 ^w ö 48, Abrasion JiOQ Skid resistance a blend OE-SBK / OB-BR κ 82.5 / 161 615 58 59 Result achieved? 48 i> Q, where SBR / BR in Ye, V- ■ 31 48 ability ₂ -Elasticity 29 51 30th Concrete wet ratio 60:40 are included, the following 170 525 82 60 30th 50 25th 47 Minutes kg / cm 300 <fo ° Shore 30th 51 DIN 23 10 ' 169 520 81 60 30th 50 141 25th 47 10 ' 141 600 56 59 28 51 150 26th 46 20 » 171 525 81 60 30th 49 135 25th 47 20 « 150 501 89 60 130 25th 44 30 » 30th 15ß ' 30 ' 138 486 86 60 128 44 40 » IpO 40 ' 141 498 83 60 127 46 Under the same Conditions will be based on the same Yulkanisa / t; ions.r§p; eptur manufactured vulcanizate from

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The mixtures are processed analogously to Example 1 to! which in turn are used to manufacture car tires dimensions 6.40 - 13 are used.

After completing a driving test over approx. 10,000 km, the following results Comparison:

Abrasion index

Tread from scrap OE-SBR / OE-BR = 82.5 / 50 = 100

Tread made from oil-extended polybutadiene with a 38 £ 1,2 component = 99

The equivalence of homopolybutadiene with the structural features mentioned compared to the special one is widespread today The waste in use is thus clearly documented.

Example 3

A butadiene polymer prepared according to Example 2 is admixed with 25 mmoles of diethylaluminum monochloride and 2.3 mmoles of tert-butyl chloride after a Mooney viscosity of 45 per 100 g of polymer has been reached. After the sudden increase in the Moöney value had practically ended, 37.5 parts of oil were added analogously to Example 1 and the mixture was worked up to give pest rubber with an ML-4 value of 37. The microstructure of the polymer contained therein is as follows:

Arrangement of the monomer units

1,4-trans

40

1,4-cis

23

1.2

37

The further processing into tire treads takes place according to the vulcanization recipe described in Example 2.

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The step heating at 151 ⁰ C (10, 20, 30, 40 minutes) leads to the following result:

ο
ο
"O

Heating time
Minutes firm
ability ₂
kg / cm strain
1> module
300 fo hardness
° Shore Rebound
22 ⁰ C -Elasticity
75 ⁰ C Away]
DIN rubbed
Pico Skid resistance
Concrete wet 10 « 135 615 53 60 28 46 156 32 44 20 « 146 525 91 61 27 52 128 28 44 30 « 140 530 93 60 27.,;. 51 131 25th 44 40 * 132 480 88 60 27 51 124 25th 43

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Again, the VuI-kanisat serves as a comparison to the state of the art from a blend OE-SBR / OE-BR = 82.5 / 50 (for results see example 2).

Both vulcanizates are again tested next to each other in the Pahr test examined for their performance as a tread material for pneumatic tires. Result:

Abrasion is ex

Tread off

OE-SBR / OE-BR = 82.5 / 50 = 100 *

Tread made from the oil-extended ^ ·. ■ · ■. Polybutadiene described here with a 37 $ 1,2 component = 102

This again results in the equivalence of the invention Butadiene polymers as tire rubber with special, state-of-the-art blends from SBR and BR.

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Claims (1)

Patent claims (a) a polybutadiene with a content of monomer units arranged in the 1,2-position of 25 "to 50 $> preferably 50 to 45 $ * of i ^ -cis-double bonds of 10 to 40 $>,. of 1. , 4-trans double bonds from 15 to 55. $ · And an ML-4 value from 4Q ^! To 12: 0; (b) from 5 to 100 parts by weight of a plasticizer, based on 100 parts by weight of polybutadiene % (c) from 50 to 120 parts by weight of a carbon black based on 100 sewing parts polybutadiene. 2 stripping according to claim 1, consisting of components (a), (b) and (c) and, as an additional component (d), of one Vulcanization system containing 1 to 5 parts by weight of sulfur and 0.5 to 2.5 parts by weight of mercaptobenzothiazole or its Derivatives, especially its sulfenamides, contains. 5. A process for the production of treads based on polybutadiene-plasticizer-filler mixtures for car tires from treads according to claims 1 and 2, characterized in that one in the presence of organolithium compounds with the addition of 0.5 to 5 Percentage by weight, based on butadiene, ethers of the general formula ROR, R'-OR, R'-OROR «, R" -OROR ·, in which R, R ¹ , R "(cycloaliphatic radicals with 1 to 20 carbon atoms and aromatic Mean radicals with 6 to 14 carbon atoms, in the presence of aliphatic or aromatic solutions 009834/1019 - 17 - OZ 2565 6.2.1969 Medium-produced polybutadiene with a content of 25 "to 50 $, preferably 30" to 45 $, of Mouomer units arranged in the 1,2-position and an ML-4 value of 40 to 120 with of 5 Ms 100 parts by weight, "based on 100 parts by weight Polybutadiene, a plasticizer and 30 to 120 parts by weight, based on 100 parts by weight of polybutadiene, an active! filler, in particular carbon black, mixed in a known manner and this mixture with the addition of the usual rubber auxiliaries in the extrusion process pressed into treads and these treads vulcanized together with the tire elements known in tire construction. 4. The method according to claim 3, characterized in that one starts from a polybutadiene with a content of 1,2-arranged monomer units of 25 to 50 $>, preferably 30 to 45 #, and ML-4 values of 10 to 60 and the ML 4 value of this polybutadiene increased to 70 to 120 under the conditions of the "molecular weight jump" process. 5. The method according to claim 3, characterized in that one starts from a polybutadiene with a content of monomer units arranged in the 1,2-position of 25 to 50 #, preferably 30 to 45 # »and Mooney values of 10 to 60 and the ML-4 value this polybutadiene immediately after the polymerization before addition of the stopper under the conditions "of the" Kopp reaction lung "at temperatures of -20 to + 200 · ⁰ O 70 bie increased 120th 009834/1019 6.2.1969 6- procedure according to. Claim 5, characterized in that one as the "coupling reaction" triggering compounds Methy lenchlprid, chloroform, especially silicon tetrahalides, and carbon tetrachloride is used. · 7. The method according to claim 3, characterized in that one starts from a polybutadiene with a content of 1,2-position monomer units of 25 to 50 $, preferably from 30 to 45 i ° -, and ML-4 values of 10 to 60 and the ML-4 value of this polybutadiene increased to 70 to 120 under the action of sulfur halides, in particular disulfur dichloride. 8. The method according to claim 3 to 7, characterized in that the tread is in the presence of a vulcanization system vulcanized, which consists of 1 to 3 parts by weight of sulfur, 0.5 up to 2.5 parts by weight of mercaptobenzothiazole or its derivatives, in particular its sulfenamides, and optionally a basic secondary accelerator. 9. Use of stereoregular polybutadiene with a content of monomer units arranged in the 1,2-position of 25 to 50 μg, preferably 30 to 45 μg, and an ML-4 value of 40 to 120, a content of 1.4 -cis double bonds of 10 to 40 fo _t a content of 1,4-trans double bonds of 15 to 55 fi in a mixture with 5 to 100 parts by weight of a plasticizer, based on 100 parts by weight of polybutadiene, and from 30 to .- ♦ 009834/1019 originally inspected - 19 - OZ 2365 6.2.1969 Parts by weight of pull st of fen, preferably carbon black, "based on 100 parts by weight of polybutadiene, for the production of treads for car tires, by extrusion, known per se, of the polybutadiene-plasticizer-carbon black mixture to treads and subsequent Vulcanization of these treads together with the tire elements common in tire construction. 009831/1019